JPS6044684B2 - Refrigeration compressor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Refrigeration systems, such as those for air conditioning in large buildings, utilize a number of compressors in parallel flow or series for the cooling of a controlled medium such as process water, cooled space, chilled water or return water. It is usually used in the flow.

In many such systems, the cooling capacity of the compressor can vary. Some systems use only a single variable capacity compressor, requiring the cooling capacity of multiple compressors. Each such compressor, e.g. York model HT25O with electrical controls, typically has an internal control mechanism and safety devices for shutoff in case of fault and protection from overload. . However, such internal controllers are only effective for controlling individual compressors and are therefore of limited value in multi-compressor systems. Moreover, the internal controller does not automatically react to changes in cooling capacity demand and is of limited value even in a single compressor system. Due to the high power demands of such refrigeration systems, it is important to ensure that the compressor system not only continues to operate, but also that the system operates efficiently, especially when considering the increased energy costs and inconveniences that arise from system failures. is important.

To this end, the cooling capacity of individual variable capacity compressors in the system is started, stopped, and increased. Various control devices have been adopted to reduce the In single-screw compressors, capacity is varied by the relative position of the coolant inlet nozzles. However, in all cases it is not necessary to change the capacity directly by vane position. Also)
However, for the sake of simplicity, capacity and vane position have heretofore been used virtually interchangeably. Some of these prior art control devices are not immune to overload problems during initial start-up, creating the possibility of interfering faults, ie shutting down the system even when there is no actual fault in the system.

For example, during start-up, many controls allow the system to ramp up to full capacity for a short period of time, thereby preventing such disturbances from occurring as a coolant cold shutdown (even though there is actually no system failure). Allow failure to occur or
Or control the water temperature excessively. Such a surge in capacity also results in short-term power consumption. A similar result is
This also occurs when the first compressor reaches full capacity and demand requires additional cooling capacity of the other compressors, causing power consumption to rise for a significant period of time upon start-up of the second compressor. Other prior art control devices have attempted to prevent this type of jamming primarily by a circuit commonly referred to as a "load limiter" that senses the compressor load current and compares it to a known maximum value. I'm trying. The control device then only allows an increase in load current of a few percent for a predetermined period of time. The ``difficulty'' of load limiter-type control systems is particularly pronounced in variable capacity centrifugal compressors, either in multiple or single compressor systems. It is not an indicator of a change in force. For example, if a material with a viscosity different from normal refrigerant conditions is accidentally injected into the compressor, the load current will increase without any change in capacity. A load limiter can cause current spiking in the circuit and cause the load limiter to inappropriately reduce capacity.Another problem with conventional controls is the It is the difficulty of maintaining a balance of abilities.

Most compressor systems use compressors of the same capacity. In order to maximize the operating efficiency of such systems and thereby minimize power demand, it is desirable to equalize or balance the capacities of the individual machines at any given moment of operation. Weighted balance is desirable in systems employing compressors of different capacities. This balancing requires two stages.

first balancing the capacities of the first operating compressors and then allocating capacity increases or decreases to the operating compressors;
To ensure that the balance of cooling capacity is substantially maintained. Allocating capacity increases or decreases can be done by sending a signal to the two compressors to make them heavier or lighter by a given amount, or by increasing the load on the compressors (
This is accomplished by alternating between (or removing) Typically the latter method is taken to minimize energy demand. However, accurate sensing of compressive force has proven difficult when combined with efficient switching control. Precise control has proven difficult even in single compressor systems.
Most prior art control systems are capable of providing only small incremental changes in cooling capacity, thus requiring a large change in demand before the controller responds to effect a change in capacity. According to the present invention, the control device senses the temperature of the medium to be controlled by a temperature sensing device that sends a floating control signal, and for an appropriate time cycle, typically a centrifugal or screwdriver of variable capacity. A command is transmitted to a leading compressor or a trailing compressor to adjust its cooling capacity in response to demand as indicated by the temperature of the controlled medium. Of course, in a single compressor system, signals are constantly communicated to the compressor. Centrifugal compressors are generally more difficult to control accurately than single-screw compressors, so this will be described in terms of centrifugal compressors. However, it will be obvious to those skilled in the art to convert this system for use in a single screw compressor. During a typical cycle of either a single or multiple compressor system, the initial application of power is followed by symptoms that require additional cooling capacity. In typical prior art practice, such requirements are met by increasing the compression capacity to maximum load, eg, 100% capacity, as discussed above. This rapid increase leads to unnecessary overload of capacity and corresponding power consumption. However, in accordance with the present invention, the cycle timer allows only an incremental increase in capacity (the magnitude of which is manually preset) during a portion of each cycle. The remainder of the cycle allows the controlled medium to react to changes in cooling capacity. If additional cooling capacity is required at the start of the next cycle, another incremental increase in compressor power is allowed, followed by the reaction time described above. Incremental increases continue until the controlled medium stabilizes at the desired temperature. By allowing only incremental increases, power perturbations are avoided, a large source of jamming outages is eliminated, and power consumption is significantly reduced.
For multiple compressor systems, in some cases a single (
In some cases, the original (original) compressor may not be able to meet the increasing cooling demands. In such cases, the present invention provides the ability to reduce the capacity of the lead compressor to some arbitrary value, and then start the second or follower compressor and bring it to any cooling capacity, regardless of cycle timing. Automatically command them to come. Typically, the sum of the capacities of both (or multiple) compressors is less than the maximum capacity of a single compressor due to the increased efficiency due to the increased surface area. By automatically reducing the capacity of the advance compressor before the successor compressor begins operation, increased power consumption is reduced. Once the leading and trailing compressors reach their respective capacities, cycle timing is allowed to command incremental load application or release to the system.

Then, as increased cooling demand is accepted during the ON portion of the time cycle, incremental increases in capacity are alternately commanded to the leading and trailing compressors. Because of the new configuration of alternating signals that change the compressor power, the present invention balances the system compressor operation more efficiently and more accurately. If cooling capacity exceeds demand, capacity is reduced incrementally in a manner similar to that described above. If demand falls below what is needed to efficiently utilize one compressor, the trailing compressor shuts down and only the trailing compressor continues to operate. A multiple compressor system operates in substantially no different manner than a single compressor, such that all incremental increase or decrease signals are then directed to a single compressor. The capacity of the advance compressor is then increased or decreased incrementally to meet demand. If demand decreases enough, the advance compressor will also automatically shut down. Other aspects of the invention provide indication of compressor failure detection, automatic load switching to remaining compressors, and local or remote control overriding automatic sequencing. One object of the present invention is to provide an improved system for the control of refrigeration compressors.

One of the objects of the present invention is to provide an improved refrigeration system controller for controlling multiple compressors from a single location. Another object of the present invention is to provide an improved refrigeration system controller that significantly reduces power consumption by the refrigeration system.

Another object of the present invention is to provide a refrigeration system controller with improved accuracy in maintaining the temperature of a controlled medium at a desired level.

Another object of the present invention is to provide a refrigeration system controller that substantially eliminates excessive power consumption during compressor startup.

Another object of the present invention is to provide an improved refrigerator control system that does not override internal protection devices.

Other objects of the invention described in this section will become clear during the detailed description below. Figures 1 and 2
1 illustrates a control device in a refrigeration system using multiple compressors.

FIG. 2 is a block diagram of the device of FIG. 1 and its interconnections.

Figures 3a-3d are schematic diagrams of the control device of Figures 1 and 2 using relays.

FIG. 3 shows the interrelationship of FIGS. 3a to 3d. Fourth
Figures 4a-4e illustrate logic gates that are equivalent to the control devices of Figures 3a-3d.

FIG. 5 is a functional block diagram of the system of FIG. 2 suitable for implementation by a microprocessor and associated circuitry.

Figures 6a and 6b are circuit diagrams of a controller for use with a single compressor system.

Referring to FIG. 1, a control device 1 connected to a first compressor 2 and a second compressor 3 is shown. The first compressor 2 sends the current blade tilt to the control device 1,
Terminals 5, 7, 9 communicating signals for system on, compressor oil out, compressor safety device failure, compressor start, increase in blade stiffness, and decrease in blade stiffness, respectively.
, 13, 15, 17 and 19.

The second compressor 3 also has its terminals 21, 23,
25, 29, 31, 33 and 35 in a similar manner, that is, the functions transmitted by terminal 21 correspond to the functions transmitted by terminal 5, and hereinafter the functions transmitted by terminals 19 and 35 correspond to each other. It is connected in such a manner as

Connected to the control device 1 are a temperature control switch 37 connected between terminals 36 and 38 and a temperature control switch 39 connected between terminals 36 and 40, respectively, for instructing a required increase or decrease in cooling.

Switches 37 and 39 are typically controlled by thermostats installed, for example, in the chilled water return line. Furthermore, a cold cutoff switch 41 is connected to the control device 1 at terminals 42 and 44. Switch 41 serves to shut off the advance compressor when the cooling demand drops below a certain predetermined value, but once the cooling demand has been established in the controlled space, the temperature of the controlled medium will never drop enough to activate this cold cutout switch 41. The parts of the control device 1 used to control the first compressor 2 are four vane indicator switches 4''3, 45, 47 and 49.

A vane switch 43, connected to the control device 1 at terminals 58 and 60 and normally open, indicates a certain minimum capacity of the compressor 2 and later details when the compressor 2 is not required for proper cooling. Used to allow blocking in the manner described. A vane indicator switch 45 connected at terminals 62, 64, and 66 has both normally open and normally closed contacts and returns when the latecompressor is started in a manner to be detailed below. Used to display conditions. Normally open blade display switch 4
7 is connected to terminals 68 and 70 and is used to display the maximum capacity of compressor 2 and to allow a second compressor to be called into operation in response to increased cooling demand. . A normally closed minimum vane indicator switch 49 connected between terminals 11 and 15 sets the vanes to some arbitrary minimum capacity, e.g. Used to locate in %. Switches 51, 53, 55 and 57 are connected to the control device 1 for use with the second compressor 3. Switch 51 is connected at terminals 72 and 74 and is similar to switch 43; switch 53 is connected at terminals 76, 74;
8 and 80 and is similar to switch 45. Switch 55 is connected at terminals 82 and 84 and is similar to switch 47. Switch 57 is terminal 2
7 and 31 and is similar to switch 49. For proper operation of the control device 1, the vane switches 49 and 57 must have a vane position smaller than the switches 43 and 51, for example 20 respectively of the maximum vane position.
% and 25%.

Additionally, vane switches 45 and 53 must be set to a greater vane position than switches 43 and 51, for example 30%. Vane switches 47 and 55 are typically set on the order of 85% of maximum vane angle, but the vane position is such that switches 47 and 55 are activated before the overload protector in the compressor is triggered. must be set. Flow switches 93, 95, 97 and 99 are also connected to the control device 1.

Flow switches 93 and 95 are safety switches that ensure the flow of cooling water through the first compressor 2 and are connected in series at terminals 7 and 96 to the control device 1 .
Flow switches 97 and 99 are similar to these, but
However, it is intended for use in the second compressor 3 and is connected to the control device 1 at terminals 23 and 100.
Turning now to FIG. 2, the internal circuitry of the control device 1 shown in FIG. 1 is illustrated in the form of a program diagram.

In FIG. 2, timer 200 operates synchronously and independently of the remaining circuit elements, including R3 transfer circuit 202, R4 transfer circuit 204, first compressor load and unload circuit 206, second compressor load and A timing signal is transmitted to the load removal circuit 218. During a portion of the timing cycle generated by timer 200, first compressor loading and unloading circuit 206 connects terminals 36, 3
8 and 40 to the temperature control switch 3 shown in FIG.
7 and 39. If increased cooling capacity is required, normally open switch 37 is closed. When neither the first compressor 2 nor the second compressor 3 is operating, i.e. when a first start-up of the system is required, for example early in the morning, the loading and unloading circuit 206 is connected to the first compressor 2. Sending a signal through terminal 17 to increase the vane angle responds to the demand for increased cooling capacity.

Load circuit 206 simultaneously sends a signal to pump start circuit 208 to complete the circuit between terminals 365 and 367 of controller 1, thereby starting the system pump (not shown). In some systems, more than one pump is used, eg, one pump per compressor. In such systems, the pump may be started by a compressor start signal. When pump start circuit 208 responds to load circuit 206, it sends a signal through compressor start circuits 210 and 212 to the advance compressor. Which of the first compressor 2 and the second compressor 3 will be the first compressor is automatically determined by the sequential circuit 216 in a manner described later.

Assume for purposes of illustration that the first compressor 2 is the advance compressor. At that time, the first compressor starting circuit 210 is connected to the terminal 15.
, a signal is sent to the first compressor 2 to start operating. Start-up of the first compressor is allowed to occur in a manner that will be described in more detail below with reference to FIG. 3a.

At this point the system pump and advance compressor have started and cooling has begun. Assuming that the initial cooling capacity of one starter compressor is insufficient to meet the demand as indicated by the normally open switch 37 being closed, the next turn-on cycle of timer 200 will be , the increased demand for cooling capacity by the first loading and unloading circuit 206 sending a signal through the terminal 17 to increase the vane angle of the first (leading) compressor 2 for a predetermined period of time. allow you to answer. Since the capacity increasing signal lasts for a limited predetermined period of time, each on-cycle of timer 200 allows only an incremental increase, typically 5%, in the cooling capacity of the system. Furthermore, since the on portion of the cycle generated by timer 200 is for a limited period of time, typically 2@, the off portion of the cycle is for a much longer period, perhaps a minute. By setting the cycle off portion of timer 200 to be longer than the on portion, the controlled media is given an opportunity to react to the increased cooling capacity of the refrigeration system, thereby increasing the system capacity to meet demand. Automatically limit to almost the bare minimum. This minimizes power consumption. Also, by allowing only incremental increases in capacity and requiring reaction time between increases, power consumption is reduced and problems such as overshoot and low coolant temperature failures are largely avoided. If the system requires additional cooling, the above sequence is repeated until the advance compressor, in this case the first compressor 3, reaches maximum capacity, typically 85% of the estimated capacity.

Maximum capacity is indicated by closing switch 47, which is normally open. The switch 47 prevents further increases in the capacity of either the load circuit 206 or the compressor 2 since the unload signal overrides the load signal in the manner described below. When the maximum capacity of the first compressor 2 has been reached but additional cooling is still required, the second compressor, in this example the second compressor 3, is transferred through the second loading and unloading circuit 218. The late compressor start circuit 214 responds by starting to load the compressor.

The late compressor starting circuit 214 also sends a signal to the second compressor starting circuit 212 to start the second compressor 3 . Start-up of compressor 3 begins as soon as compressor 2 reaches maximum capacity or 85%, which normally occurs during the on cycle of timer 200. However, the compressor's internal controls will prevent the machine from actually starting for several minutes. At the same time that the late compressor starting circuit 214 sends a starting signal to the second compressor 3, the vane switch 45 is activated.
Since the normally open contacts of the complete the circuit through the unloading portion of circuit 206, it is possible to unload to a predetermined value, e.g. 30% of maximum capacity, through the first compressor loading and unloading circuit 206. ! The output signal is also sent to the compressor 2.

Although the first compressor does not need to be unloaded due to any circuit problems, maximum efficiency of the circuit requires that the power demand be minimized.

This unloads the first compressor by a predetermined value and the second compressor, in this example the second compressor 3, is fed from the second compressor start circuit 214 to the second compressor start circuit 212. This is accomplished by allowing the signal to start loading to some minimum value. Once loading of the second compressor is initiated, the normally closed contacts of vane switch 52 will require compressor 3 to continue to be loaded until a predetermined minimum capacity is reached. .

When the minimum capacity is reached, the normally closed contacts of the switch 53 open. Typical compressors used in refrigeration systems have an internal delay device for start-up, so that the first compressor 2 is delayed before the second compressor 3 begins to load to a minimum value. It will be unloaded to a predetermined 7 value. For compressors in pairs, compressor 2
The unloading value to is equal to the loading value to the compressor 3 in order to maximize the energy savings achievable by the invention.
However, such equalization is not necessary, and a weighted balance is optimal in systems that do not use paired compressors. At this point, the late compressor start circuit 214 is responsive to the signal from the vane switch 214 and signals the start circuit 212 to begin operation of the compressor 3. Both compressors 2 and 3 are therefore operating, albeit at substantially less than maximum capacity, for example 30% capacity. It should be noted that the sum of the cooling capacities of the compressors is preferably lower than the maximum capacity of one compressor. This is because an increase in cooling efficiency is observed with an increase in the surface area available for cooling from the two compressors. The subsequent presence of an increase in cooling capacity is indicated by the closing of normally open switch 37, which then closes the lead compressor, in this case compressor 2, during the next turn-on cycle of timer 200. is loaded as described above.

It should be noted that although compressors 2 and 3 are both operating at this point, the demand for increased cooling capacity does not result in an increase in the capacity of both compressors 2 and 3 at the same time. When a demand for increased cooling capacity is indicated, the capacity (or load) of the lead compressor, compressor 2 in this example, is increased during the first turn-on cycle of timer 200. The i compressor 3 is increased in load during the next timer 200 on cycle where there is a demand for increased cooling capacity.
This is achieved in the following manner. During the first turn-on cycle of timer 200 when there is a demand for increased capacity after both compressors have been operating at minimum capacity, R3 transfer circuit 202 transfers the leading compressor (compressor'.
2) requires that the capacity be increased incrementally as described above. Once the first compressor has finished increasing its capacity incrementally, the R3 transfer circuit 202 transfers the capacity of the second compressor 3 to the next timer 200 where the temperature switch 37 indicates the demand for additional cooling. Increase during on cycle. When the second compressor 3 is increased in load, the R3 transfer circuit 2
02 loads the first compressor 2 for the next demand.

The demand for increased capacity in this way is met by alternately increasing the capacity of each compressor until the demand is satisfied. System stability can be maintained using a temperature switch that is sensitive to one degree temperature changes since the timing of the circuit allows only incremental increases (or decreases) in capacity. The temperature of the medium controlled in this way can be kept within a range of 1 degree. This is in contrast to proportional sensing controllers, which are stabilized by allowing the temperature of the controlled medium to vary over a wide range, perhaps 10 degrees. Finally, the system capacity will increase until it fully satisfies the demand, and the normally open switch 37 will remain open during the timer 200 on cycle.

At such times, no load or unload signals are generated by circuits 206 and 218, and R3 transfer circuit 202 remains dormant until the next capacity increase demand. When there is a demand for a reduction in the capacity of compressors 2 and 3, normally open switch 39 closes and normally closed switch 37 remains open, thereby reducing the load during the appropriate on cycle of timer 200. and signals to unload circuit 206 and R4 transfer circuit 204 that reduced capacity is required.

At that point, the unloading circuit 206 sends a signal to the compressor blade tilt motor to reduce the blade tilt angle of the centrifugal compressor 2 via terminal 17 on the controller shown in FIG. R4 transfer circuit 204 performs a similar function to R3 transfer circuit 202 in that it alternates with incremental unloading while R3 circuit 202 switches when loaded. In this embodiment of the invention shown in FIG. 3, the capacity of the advance compressor is reduced first, but it should be noted that in all cases the advance compressor need not be unloaded first. . As will be appreciated by those skilled in the art, the compressors are alternately switched to maintain a relatively balanced capacity, so it does not matter which of the leading or trailing compressors is unloaded first. In this way, when the normally open switch 39 is closed, the next turn-on cycle of the subsequent compressor, in this example the second compressor 3, is During this period, the compressor is unloaded through a signal applied to the second compressor load and unload circuit 218. Compressor loading and unloading circuit 218 is substantially similar to circuit 206, except that circuit 206 controls the first compressor 2 while loading and unloading circuit 218 controls the second compressor, as described above. The above is the same. Furthermore, 1
Similarly to unloading the second compressor 2, a signal from temperature control switch 39 connects load and unload circuit 218 and R4 during the appropriate on cycle of timer 200.
The transfer circuit 204 is commanded via the terminal 33 of the controller 1 to reduce the capacity of the compressor 3 by decreasing the blade inclination angle of the compressor 3. If the demand to reduce cooling continues to exist, both compressors will be reduced to a predetermined minimum capacity, e.g. compressor 2 or 25%, below which is insufficient to operate both compressors. The output is alternately reduced by incremental amounts as described for load until one of 3 is reached.

This minimum capacity is determined by vane switches 43 and 51 for compressors 2 and 3, respectively. At this point the system requires the second compressor to be incrementally reduced in output by 25% during the next turn-on cycle of timer 200 where there is a demand for reduced cooling.
If the first compressor to reduce to 25% is the advance compressor, the system will reduce the capacity until both compressors are at 25% of their maximum capacity, or some other predetermined minimum. Requires the latecompressor to be stepped down in the previously described increments. If an intermittent demand for reduced cooling results in commanding the advance compressor to reduce its capacity below a predetermined minimum value, which is 25%, the loading and unloading circuit 206 The condition is detected internally via switch 49, thereby preventing circuit 206 from reducing compressor 2 capacity below 20%. When the trailing compressor receives a signal to be reduced below its minimum capacity, vane switch 57 and circuit 218 will prevent further reduction in capacity. In this way, only the compressor that is not at minimum capacity is still incrementally reduced in capacity, so that eventually both compressors reach the minimum capacity detected by switches 49 and 51. When both compressors reach a predetermined minimum capacity, the trailing compressor start circuit 214 receives a signal from vane switches 43 and 51 and sends a signal to shut down the trailing compressor, in this case compressor 3. If the cooling capacity is greater than 25% of the preceding compressor 2 or the capacity that can be satisfied with a predetermined minimum value, the load on the first compressor 2 is started as described above. It will be appreciated that at this point only compressor 2 is operating. When the minimum capacity of the compressor 2 exceeds sufficient capacity to meet the demand for cooling the system, the controller 1 transfers control of the compressor 2 to the low temperature controller 41. In response to the decreasing demand for cooling, vane switch 41 sends a signal to pump start circuit 208 and compressor start circuit 21
0 and the pump starting circuit 208, both the first compressor 2 and the compressor pump are shut off. The above description assumes normal operation of all system components, including compressors 2 and 3.

In some situations this may not be the case and system failure may occur. In this case, fault cutoff circuit 2
20 is the compressor 2 and 3 or the flow switch 93, 9
5, 97, and 99, it is recognized that a compressor failure has occurred or that the control device 1 has failed. Faulty circuit 2
20 then prevents operation of one or both compressors depending on the type of failure. For example, if a compressor does not start when commanded by controller 1, fault circuit 220 will automatically send a signal to start the remaining compressors, but the system will not start the next compressor. Prevent automatic restart following a system shutdown. However, manual override means are provided to operate a single compressor while the remaining failed compressors are being repaired. Attention is now drawn to FIGS. 3a, 3b, 3c and 3d, which illustrate a preferred embodiment of the invention using relays, making it possible to understand the detailed operation of the control device 1. It is illustrated as a whole.

The basic transfer and flow of this system has been described in connection with FIG. 2, and the following only repeats that description in some detail. Upon initial startup, terminals 94 and 98
Electric power is applied to.

This is illustrated in Figure 3a by the normally closed bimetallic normally closed contacts 30 of the signal timer 305.
3, power is applied to variable timer relay 301.
When timer relay 301 is energized, its normally open contacts 307 close and turn on signal timer 3
After 05 timing periods, the timer signal relay 309
generate an asymmetric square wave at the In the embodiment described in this section, the off cycles in timer signal relay 309 are typically adjustable up to one point by adjustable timer relay 301, and the on cycles in timer signal relay 309 are typically is fixed to about 100 seconds. However, these numbers are arbitrary;
And many possible variations will be recognized by those skilled in the art. During the ON portion of the cycle in timer signal relay 309, normally open contacts 311 (Figure 3b) of timer signal relay 309 close and connect terminal 36 to either terminal 38 or 40, subject to the conditions described below. Allow power to pass between them.

A temperature control switch 37 is connected between terminals 36 and 38 as discussed in connection with FIG.
9 is connected between terminals 36 and 40. Further, as described in connection with FIG. Whenever detected, normally open switch 37 closes and switch 39 opens. It can thus be seen that when switch 37 closes, power passes between terminals 36 and 38 in Figure 3b. Assume, for purposes of illustration only, that switch 37 is closed.
Further assume that the automatic first-last switch 313 is in the first position and that the two sequential relays 315 and 317 are de-energized. It should be noted that relays 315 and 317 are simple parallel relays, and may even be a single relay depending on the number of contacts of the particular relay used. In addition, first safety relay 319 and second safety relay 321 are energized, and first oil out relay 323, second oil out relay 325, first flow switch 331 and second flow switch 333 are all energized. Assume that the first safety indicator relay 327 and the second safety indicator relay 329 are not energized. Given these initial conditions, the increased cooling demand indicated by switch 37 being closed results in the following operating sequence. When time signal relay 309 is energized, adjustable solid-state timer 335 (FIG. 3b) is also energized, and normally open contacts 337 close, which energizes second control timer relay 339. do.

As a result, between terminals 94 and 98, contact 311 of timer signal relay 309, terminal 36, switch 37, terminal 38, normally closed contact 341 of R3 relay 343,
, resulting in a continuous circuit being formed through the normally closed contacts 345 of the second control timer relay 339, the normally closed contacts 347 of the first unload relay 349, and the first load relay 351. Become. It should be noted that the second control timer relay 339 is not energized until the control timer 335 times out and contacts 345 open to end the duty cycle.

Furthermore, terminal 1 through contact 341 of R3 relay 343
The signal from 353 also causes the second bimetallic time delay timer 353 to begin timing as discussed in more detail below. Control timer 335 is typically an adjustable timer having a time period that can vary from the on-cycle time period of timer signal relay 309 . It can be seen that because timer 335 controls relay 339, first load relay 351 is energized for the length of timer 335 was adjusted. When the first load relay 351 is energized, its normally open contacts 355 located in the pump starting circuit 208 (FIG. 3a) close, and the normally closed contacts 357 of the first unload relay and second unloading relay 361
completes the circuit through normally closed contacts 359 of , thereby energizing pump start relay 361 . When pump start relay 361 is energized, its normally open contacts 363 close and terminal 36
5 and 367, thereby starting the compressor pump (not shown). Furthermore, when the first load relay 351 is energized, its normally open contacts 369 (FIG. 3c) close, and terminals 5 and 17
Allow the completed circuit between. Voltage is supplied to terminal 5 whenever the controller inside the compressor indicates a demand for cooling. By setting the compressor internal control to a value below the intended chilled water temperature, the compressor internal control can be used as a signal source for loading or unloading the compressor through the controller 1. By doing so, the control device 1 can operate without overriding any of the control devices inside the compressor. Terminal 21 is similarly limited by the second compressor. Closing this circuit is accomplished by sending a vane switch 4 to the compressor 2 control panel, typically set to 20% of maximum capacity.
signal to increase the compressor blade inclination angle to a predetermined minimum value determined by the position of 9. When power is first applied to terminals 94 and 98, 1
The first program motor relay 370 and the second program motor relay 372 are energized, closing the normally open contacts 374 of relay 370 (during normal operation) and the normally open contacts 376 of relay 372.
1st and 2nd minimum vane relays 469 and 48
3 are also energized through normally closed vane switches 49 and 57, respectively.

This is true regardless of the condition of the first load relay 351 or the second load relay.
The circuit is completed between terminals 5 and 17 and 21 and 33 until the minimum vane angle, indicated by the opening of 7, is reached. The first compressor 2 is started by a signal from terminal 15 in the compressor starting circuit (Figure 3d).

Terminal 15 is connected to the control panel of compressor 2 and is always at a supply voltage sufficient to trigger the compressor's internal starting circuit. The signal applied to terminal 7 is thus applied to the normally closed contact 371 of the fifth bimetallic delay timer 373, the normally open contact 375 of the energized first safety relay 319, and the normally open contact 375 of the de-energized sequential relay. 315
normally closed contacts 377 of the energized pump start relay 361, normally open contacts 379 of the energized pump start relay 361;
Normally closed contacts 381 of the th order relay 315
The circuit to terminal 15 is completed through. A signal is thus applied to terminal 15, which starts compressor 2, but
However, if a signal is also applied to terminal 383 adjacent to terminal 15, and there is a fault in the internal control of compressor 2, fault circuit 220 will shut down the compressor in the following manner. When the first condition is ready, relays 323 and 313 are all energized, while relay 327 is energized.

When inactive, the normally open contacts 385 of the first safety indicator relay 327 connect to the ninth bimetallic delay timer 387 and the fifth bimetallic timer 373.
(as a backup) and sends a signal to the first safety relay 319 which interrupts the signal to terminal 15. Fault isolation circuit 220 will be discussed in detail in connection with FIG. 3a. In a similar manner, the normally closed contacts 389 of the first oil fault relay 323 and the first
The normally closed contact 391 of the second flow switch relay 331 interrupts the start signal to the terminal 15. Assuming no fault has occurred, the conditions of the circuit at this point are such that the compressor pump start open circuit has activated the pump start circuit through terminals 365 and 367 and compressor 2 has started. If the demand for increased cooling continues to exist, the next turn-on cycle of timer signal relay 309 triggers control timer relay 335 in the manner described above.

The control timer relay 335 then signals the second control timer relay 339 which relays the first load relay 351 only during the time span of the control timer 335.
energizes, thus allowing an incremental loading of the compressor 2 as described above. Control timer relay 335 is typically an adjustable solid state timer that is allowed to vary in increments of capacity over a predetermined range. Typically, such increases are 5% during each on-cycle, and the blade angle increments of compressors using such controllers increase at approximately 1% per second. . However, the time required varies depending on the type of compressor. If the timer 200 has a 5-minute off cycle and 2 on-cycles, during which a control timer puzzle occurs, a 15% increase in performance is obtained over a range of about 1 minute. The load on the lead compressor, in this example the first compressor 2, continues to increase incrementally as described above with each cycle of timer 200 on.

When the demand for increased cooling capacity continues to exist for a sufficiently long period of time, the compressor 2 is loaded to its maximum capacity beyond which its operation becomes ineffective in terms of energy consumption. The capacity of a compressor to fail is normally determined by the design of the compressor itself, and typically the maximum efficient capacity will be 85%. When the demand for increased cooling capacity causes the capacity of compressor 2 to reach a predetermined maximum value, the capacity of compressor 2 is reduced to the predetermined value and compressor 3 is reduced in the following order: It will start automatically. When compressor 2 reaches 85% of capacity,
The normally open vane switch 47 closes, completing the circuit between terminals 70 and 68 (Figure 3c). This is next 1
Normally closed contact 3 of the th sequential control relay 395
93 to complete the circuit between terminals 68 and 78. It should be noted that sequential relay 397 and first sequential relay 395 are simply parallel relays, and may be a single relay. Once the circuit to terminals 7-8 (and also to terminal 64) is completed, a circuit is completed through the normally closed contacts of vane switch 53, allowing power to reach terminal 80. Power is terminal 80
(FIG. 3c), a circuit is completed through normally closed contacts 399 of sequence relay 317, thereby energizing cycle relay 401.

It should be noted that sequential relay 317 is not energized satisfying the conditions originally assumed. When the recycle relay 401 is energized, it is locked in the energized state via the normally closed contacts of the vane switch 53, and its normally open contacts 403 indicate that the vane position of the second compressor 3 is The circuit is completed between terminal 68 and sequential control relays 395 and 357 until the normally closed contacts of switch 53 reach the open position. At the same time, normally closed contacts 405 of recycle relay 401 close, maintaining a continuous circuit between terminals 68 and 78. Also, the normally open contact 407 of the recycle relay 401 is closed, and the circuit is passed through the normally closed contact 409 of the sequential relay 317 and the normally closed contact 411 of the second unloading relay 361 (FIG. 3b). Complete. The second load relay 413 is energized. Feather switch 47
indicates that the first compressor 2 has reached its maximum efficiency capacity, thereby signaling the start of the trailing compressor, the leading compressor, here compressor 2, in the following manner. automatically reduced to some substantially lower capacity.

When voltage is applied from vane switch 47 to terminal 68, this voltage reaches terminal 64 as described above, which provides power to vane switch 45 as illustrated in FIG. Since the normally open contacts of vane switch 45 are closed when the first compressor 2 reaches the capacity to which vane switch 47 is set, application of voltage to terminal 64 transfers the voltage to terminal 62 ( (Fig. 3c).
This connects the unload relay 349 (Figure 3b) to the normally closed contact 509 of the sequence relay 317 (Figure 3c), and the normally open contact 5 of the energized recycle relay 401.
10, and normally closed contact 5 of sequence relay 317.
Excite through 05. 1st unload relay 349
When energized, its normally closed contacts 347 become
The first load relay 351 is de-energized, and the first
through the normally open contacts 374 of the first program motor relay 370, the normally closed contacts 467 of the first minimum vane relay 469, and the normally open contacts 465 of the energized first unload relay 349. , completing the circuit between terminals 5 and 19.

This unloads the first (leading) compressor 2 until the closed, normally open contacts of the vane switch 45 open again. As previously mentioned, switch 45 is typically set at 30% of maximum blade position. Since the vane position and associated compressor function power is
4 is reduced to 30% by this signal, and at the same time the second compressor 3 is loaded and started. The second compressor 3, in this example a latecompressor, is started by a signal applied from terminal 23 to terminal 31 in the following manner. The continuously present terminal 23 voltage is transferred to the terminal via the normally closed contact 417 of the seventh delay timer 419 and then via the normally open contact 423 of the manual reset switch 421 or the second safety relay 321. 3
Added to 1. This voltage then passes through the normally open contact 425 of the eleventh delay timer 427, which then energizes the second safety relay 321. The voltage at terminal 23 is the normally closed contact 4 of sequential relay 315.
Pass through 29. Normally open contacts 43 of energized second compressor start relay 395 when late compressor start circuit 214 receives a signal from vane switch 53 that energizes second compressor start relay 395 as described above.
1 is closed, and the voltage at terminal 23 is transferred to terminal 31 through the normally closed contact 433 of the first sequential relay 315.
added to. A voltage signal at terminal 31 starts the late compressor or second compressor 3. Advance compressor 2
Similarly, through the normally closed contact 435 of the second flow switch relay 333 or through the normally closed contact 437 of the second oil fault relay 325.
Alternatively, a fault within the compressor 3 may be indicated through the normally open contacts 439 of the second safety fault relay 329. Any of these faults will activate the seventh bimetallic delay timer 419 and the ninth bimetallic delay timer 427, opening the circuit between terminals 23 and 31, thereby shutting off the trailing compressor 3. Timers 419 and 427 are timers 373 and 387.
Similarly, it is a normally closed timer with a time range of 1 @ or less to (4) seconds or more, depending on the compressor used. Assuming no fault is detected, the system operates with lead compressor 2 operating at a predetermined low capacity, e.g. 30%, the trailing compressor starts, and returns to the predetermined capacity, typically also 30%. It's in the conditions it was brought to.

If the controlled medium still requires additional cooling capacity, which is again indicated through the temperature control switch 37, the control device 1
requests an increase in the capacity of the advance compressor 2 as follows.

In connection with Figure 2, it was pointed out that either the leading compressor 2 or the trailing compressor 3 can be the first compressor to load during operation of both the leading and trailing compressors. However, in the particular embodiment shown in FIG.
It was further noted that the lead compressor, assumed to be compressor 2, is loaded first. The reason is that the normally closed contacts 444 of the second compressor start relay 397 open earlier than its normally open contacts 445 close, so that the R3 relay 343 is forced to open before the next turn-on cycle of the timer 200. This is because it is de-excited at the beginning. The R3 relay 343 is thus deenergized, creating a load on the compressor 2 in the same manner as the initial load described above. However, as described in connection with the initial start-up, in addition to the relay activated during loading, a second bimetallic delay timer 35, which is a normally open timer, is activated during loading.
3 closes and starts timing. This closes its normally open contacts 441 found in R3 transfer circuit 202 (Figure 3b). It should be noted that the duration of delay timer 353 must be greater than the duration of the on-cycle of timer signal relay 309. This generates a completed circuit or power between terminals 94 and 98 after the timer 200 on cycle is completed. That is, there is a circuit completed through normally closed contacts 443 of timer signal relay 309 and normally open contacts 441 and normally open contacts 445 of energized second compressor starting circuit 397. This energizes R3 transfer relay 343. R3 relay 34
3 is energized, the normally open contact 4 of relay 343
47 and the normally closed contact 449 of the first bimetallic delay timer 451 and the normally open contact 445 of the second compressor start relay 397. As will be described later, failure of second safety relay 321 causes normally open contacts 453 to open and also de-energizes R3 relay 343. However, during normal operation, when R3 relay 343 is energized, its normally closed contacts 341 (near terminal 38) open and at the same time its normally open contacts 455 close.
This is a timer 20 while there is an increased cooling demand.
During the next on cycle of 0, the generated load signal is sent to the second load relay 4 instead of the first load relay 351.
13. The passage is the first load relay 3
It can be seen that this is similar to that for 51. That is, current flows through contact 455 of R3 relay 343, then through normally open contact 457 of second control timer relay 339, through normally closed contact 411 of unload relay 361, and then through contact 411 of unload relay 361, and then through contact 457 of second control timer relay 339, through normally closed contact 411 of unload relay 361, and then through contact 457 of second control timer relay 339, through normally closed contact 411 of unload relay 361, and then through contact 411 of unload relay 361. relay 413
flows through. This increases the capacity of the second compressor 3, which is the successor compressor, by the signal applied between the terminals 21 and 33 described above. At the same time, the normally closed first bimetallic delay timer 451 begins timing. Similar to the second delay timer 353, the time width of the first bimetallic delay timer is slightly longer than the on-cycle of the timer signal relay 309.

The normally open contacts 459 of the timer signal relay 309 are therefore opened and at the same time the first delay timer 4
The normally closed contact 449 of R3 relay 3 also opens.
43 is de-excited. This causes the vane position of the starter compressor 2 to be increased in the next cycle where there is a demand for increased capacity. From the above explanation, for the R3 transfer circuit 202,
It can be seen that during the appropriate on cycle of timer 200, increases in capacity are alternately commanded to lead compressor 2 and trailing compressor 3.

In this way, a proper balance of the vane positions of compressors 2 and 3 is maintained, and system efficiency is maximized, thereby minimizing power consumption. If additional cooling capacity is required, the leading compressor 2 and trailing compressor 3 are loaded alternately as described above.

Since good system design prevents both the first compressor 2 and the second compressor 3 from being loaded to their maximum capacity, the system can increase the required capacity at some value below the maximum. is allowed. The system will thus stabilize at a cooling capacity where switch 37 is no longer closed, in other words there is no increased demand for cooling, and switch 39, which is normally open, remains open. and 39, but depending on the compressor used, this width can be reduced to less than 1 degree while maintaining system stability. In R3
During the next on cycle of timer 200, the relay is neither energized nor de-energized, depending on its last state while demand was requested, and therefore R3 transfer circuit 202
remains dormant while there is no increased demand for cooling. At some point the system will require less cooling capacity and the reduced demand for cooling will now be indicated by the closing of normally open switch 39 controlled by the rethermostat.

Switch 39 is typically applied in air compressor control systems and includes a set of normally closed contacts to ensure that a failure of the air compressor locks controller 1 into a no-load mode. Similar to the process of increasing capacity, commands to decrease capacity are only received by the controller during the ON portion of the timer signal relay 309 cycle. That is, during the ON signal of the timer signal relay 309, its normally open contacts 311 close;
Due to the condition of switch 39, a circuit is then completed between terminals 36 and 40. This is the normally closed contact 461 of the R4 transfer relay 463 and the control timer relay 3.
terminals 94 and 9 through normally closed contacts 465 of 39.
The first unload relay 349 is energized by completing the circuit within 8 seconds. First unloading relay 34
9 is energized, the normally open contacts 37 of the first control relay 370 and the normally open contacts 465 of the first unloading relay 349 and the first minimum vane relay 4
terminals 5 and 19 through normally closed contacts 467 of 69.
The circuit is completed between.

In this manner a signal is sent to the first compressor 2 indicating that the blade angle should be reduced. 1st unload relay 3
The fourth bimetallic delay timer 469 is a bimetallic timer that is normally open at the same time that 49 is energized.
is excited and starts timing.

Like the second bimetal delay timer 353, the fourth bimetal delay timer 469 has a slightly longer time width than the ON portion of the timer signal relay 309.

As a result, the bimetal timer 496 is activated. During the time that the timer signal relay 309 is closed and de-energized, the R4 transfer relay 463 is energized. The circuit connects normally closed contact 443 of timer signal 309, then normally open contact 473 of timer signal relay 309, and then
th bye. It is completed through normally open contacts 473 of metal timer 469 and normally open contacts 475 of second compressor start relay 397 . It should be noted in this case that this circuit is very similar to the circuit that energizes the R3 transfer relay 343 during load sequence. R
4 When relay 471 is energized, contact 4 is normally closed.
61 opens, thus preventing the first unload relay from energizing during the next on cycle of timer 200. When relay 471 is excited at the same time, R4 relay 471
The normally open contact 477 of is closed. The timer 20 while there is thus a reduced demand for cooling.
During the next on cycle of 0, the circuit to energize the second unload relay is completed. This circuit includes terminal 311 of timer signal relay 309, terminals 36 and 40, R4
Power supply terminals 94 and 98 are supplied through contacts 477 of relay 471 , normally closed contacts 479 of second control timer relay 339 and second unloading port 361 .
It will be completed between. This is the second smallest blade relay 4
An unload signal is generated between terminals 21 and 35 through normally closed contacts 481 of 83 and normally open contacts 485 of energized unload relay 361 . When the second unloading relay 361 is energized, the third bimetallic delay timer 487, which is a normally closed timer similar to the first bimetallic delay timer 451, opens and exceeds the ON signal of the timer signal relay 309. It stays open for a little while.

This is the normally open contact 489 of R4 relay 471.
, the locked circuit formed by normally closed contacts 491 and 475 of third delay timer relay 487 is broken at contact 491 and timer signal relay 309, so that R4 relay 471
de-excite. In this way R4 relay 471 is de-energized and timer 2
In the next cycle of 00, the first compressor 2 is unloaded. R4 transfer circuit 204 and R3 transfer circuit 202 again
Noting the similarity to It should be noted that there are some that operate during unloading. Since the transfer circuits for loading and unloading are independent, the maximum imbalance in vane position between compressors is an incremental increase or decrease. As discussed above, lead compressor 2 and trailing compressor 3 continue to be unloaded while the condition of temperature switch 39 indicates a demand for reduced cooling capacity.

If a demand for increased cooling occurs, a load will be created in exactly the same manner as previously described with respect to R3 transfer circuit 202, load and unload circuits 206, and 218. However, if demand for increased capacity does not occur and the system continues to require reduced cooling, then both compressors 2 and 3
The compressors are alternately derailed until one compressor reaches a predetermined minimum vane position, typically 25% of the maximum vane position, fixed by vane switches 43 and 51, at which operation becomes inefficient. loaded. Of course, both compressors will not reach the predetermined minimum capacity at the same time;
Rather, one of the compressors reaches a predetermined minimum value;
It will then probably attempt to reduce below the minimum capacity during the cycle in which the unload signal is present. However, the fact that either compressor reaches the minimum capacity first means that the compressor's vane angle can be adjusted by either the vane switch 49 (if compressor 2 reaches the minimum capacity first) or the vane switch 47 (if compressor 2 reaches the minimum capacity first). In case of machine 3), the set value is typically reduced to less than 20% of the maximum blade angle.
This can occur because the unloading circuit 206
The normally closed contacts 467 of the first vane relay 469 (which is controlled by the vane switch 49) are opened when attempting to reduce the vane angle below the set value of the switch 49. This can be understood by paying attention to the circuit between 19 and 19. This breaks the circuit between terminals 5 and 19, causing a loss of power to terminal 19 and compressor 2.
is prevented from being unloaded further in response to a signal from the control device 1. Similarly, if compressor 3 reaches minimum capacity and attempts to continue reducing capacity, 2
Normally closed contact 48 of the smallest blade relay 483
1 is opened by the opening of vane switch 57, thereby opening the circuit to terminal 35. This means that terminals 48 and 7
2 occurs because it is connected through the energized second compressor start relay 397. As demand for reduced cooling capacity continues to exist, the remaining compressor reduces its capacity until it reaches a predetermined minimum value. At this point, the second compressor start relay 397 is deenergized as vane switch 51 or 43 opens to remove power to terminals 48 and 72. This means that the second compressor start relay 3
Normally open terminal 431 of 95 opens, thereby cutting off power to terminal 31 found in compressor starting circuit 212 (Figure 3d), thereby shutting off latecompressor 3. Thus, when compressors 2 and 3 reach 25% of their capacity, trailing compressor 3 automatically shuts down, and at 25% (or even 20%) of the leading compressor 2's maximum blade position. Continue driving. When additional capacity is required for cooling, switch 37 is closed during the next on cycle of timer 200 and loading is initiated as previously described for the first compressor 2 only. However, if a lower capacity is sufficient to satisfy the system, the command for compressor 2 is transferred via terminals 42 and 44 to low limit cut-off switch 41. relay 397
It should be noted that switch 43 no longer has any effect since it is no longer energized. If the demand for cooling is limited enough to allow cold shutoff switch 41 to take control, opening switch 41 disconnects the circuit to pump start relay 361 (Figure 3a), thereby disconnecting the circuit. energizes and opens normally open contacts 497 in pump start circuit 208 and connects terminal 15 via normally open contacts 379 of pump start relay 361.
Turn off the power to. This stops the compression pump, which in turn stops compressor 2. In this way the system is completely stopped. When the system is shut down, an automatic delay switch 313 switches its position in response to a switching signal applied to terminal 6, so that the lead compressor now becomes the trailing compressor, as was previously the case. , or vice versa.

The switching signal is generated outside the control device 1. In addition, the delay switch 313 typically includes a manually selectable position for setting either the first compressor 2 or the second compressor 3 as the lead compressor.
Therefore, in this example, since compressor 2 was the first compressor,
Compressor 3 will become the advance compressor at the next start-up. The above occurs because switching the position of first-last switch 313 allows energization of sequential relays 315 and 317 as soon as power is applied to terminals 94 and 98 during initial start-up. In such a situation, all normally closed contacts of sequential relays 315 and 317 will open and remain open until the next system shutdown. In contrast, all of the normally open contacts of sequential relays 315 and 317 close on the next toggle of switch 313, preventing false activation. Although this affects the order in which compressors 2 and 3 enter operation and are subsequently loaded and unloaded, in all other respects operation is as previously described. This means that order relay 315
This is obvious from the parallel relationship between the normally open contacts and the normally closed contacts of 317 and 317. For example, the normally open contact 499 (Figure 3c) is replaced by the normally closed contact 399 (Figure 3c).
and normally open contact 501 is similar to normally closed contact 505 and open contact 5
07 is similar to normally closed contacts 509, all of which are found in the after-compressor start circuit 214 and the load and unload circuits 206 and 218 (Figure 3b). Additionally, compressor starting circuits 210 and 212 (3d
In Figure), normally open contact 511 is similar to normally closed contact 377, while normally open contact 513 is similar to normally closed contact 433, and normally open contact 515 is similar to normally closed contact 433, and normally open contact 515 is similar to normally closed contact 433, and normally open contact 515 is similar to normally closed contact 433. Closed contact 38
It is similar to 1. Thus, the only effect of first/last switch 313 is simply to change the operating order of compressors 2 and 3, thereby ensuring substantially equal usage of each compressor. I can understand. This is the vane switch 43, 45, 47, 49 (
1st compressor 2), 51, 53, 55 and 57 (for
It has been assumed that the second compressor 3) is directly controlled by the first compressor 2 and the second compressor 3.

In practice this is not accurate and the switch described above is triggered from a signal generated by a programmed motor which is adjusted to replicate the actual blade position. By using a programmed motor that is timed to run at substantially the same speed as the actual compressor blade motor, the controller 1 can be connected to the first compressor 2 or the second compressor 3. When there is a system that does not require an electrical connection, but instead uses only an electrical connection (for example, when the vane position of the compressor 2 is being increased by the signal at the terminal 5), the contacts of the control relay 370 374 and either contact 368 of minimum vane relay 469 or contact 369 of first load relay 351 to complete the circuit to terminal 17. This adds power to the actual compressor blades. At the same time, power is applied to the incremental controller of program motor 621 through corresponding contacts 623 of control relay 370 and contacts 625 of first load relay 351 or contacts 627 of minimum vane relay 469. This allows the specially selected program motor to track changes in the actual vane position of the first compressor 2. Operation is slightly different during unloading.

Contact 629 of minimum blade relay 469 corresponds to contact 467, and contact 631 of first unloading relay 349 corresponds to contact 465. However, the normally closed contacts 633 of the first control relay 370 provide a bypass rather than a series connection to control the unload line of the program motor 621. This is because the compressor's internal controller requires that compressor 3 be unloaded, which then requires power to be removed from terminal 5 (by the compressor itself) and applied to terminal 19. be. This is the minimum vane relay 4 to unload the program motor.
69 or the first unloading relay 349. Contacts 633 of control relay 370 provide this necessary path. The operation of the second program motor 635 for the second compressor 3 is similar.

The contact 637 of the second control relay 372 corresponds to the contact 376, the contact 639 of the second load relay 413 corresponds to the contact 415, and the contact 641 of the minimum blade relay 483 corresponds to the contact 637 of the second control relay 372.
corresponds to its contacts 366 and all control the increment line 643 of the program motor 635.

For unloading, the contact 645 of the second minimum blade relay 483 corresponds to the contact 481, and the contact 647 of the second unloading relay 361 corresponds to the contact 485. Similar to the first compressor 2, the contacts 649 of the second control relay 372 provide a bypass of the reduction line 651 of the second program motor 635, so that the second program motor 635 It is capable of responding to changes in vane position signaled by the controller.

An alternative to the program motor and vane switch described in this section is a multi-position, relay or solenoid activation switch as described with respect to FIGS. 6a and 6b. In the solid state embodiment of the invention shown in FIGS. 4a-4e and 5, the program motor is replaced by a timer. The above explanation is based on compressor 2
and 3, and proper normal operation of the control device 1 have been assumed.

However, it is inevitable that failures will occur that disrupt the operation of one or both compressors. In this case, the invention advantageously utilizes an internal fault detection device of the compressor and also detects faults within the entire system including the control device 1;
It includes various means for notifying the user. first and second oil fault relays 323 and 325, all located in fault isolation circuit 220 (Figure 3a);
1st and 2nd safety indicator relays 327 and 329
, the first and second flow switch relays 331 and 333 were previously discussed. These relays indicated a failure within the compressor itself. As previously discussed, a fault that causes these relays to depart from their normal state will de-energize the first safety relay 319 or the second safety relay 321 and cause the normally closed state of the fifth bimetallic timer 373 to de-energize. Contact 371 and 9th bimetal timer 38
3 (with respect to compressor 2) or by opening the 7th bimetallic timer 41
Opening the 9th normally closed contact 417 and the 11th normally closed contact 425 of the bimetallic timer 427 (with respect to compressor 3) will shut off the failed compressor 2 or compressor 3. Each of these timers typically has an adjustable time range down to the minute mark. At the same time, normally open contacts 517 of safety relay 319 or normally open contacts 519 of safety relay 321 connect the common side of vane switches 43, 51, 55 and 47 through terminals 60, 74, 84 and 70, respectively. disconnect. This prevents more than one compressor from operating during on-cycles in which the fault continues to exist, since vane switches 47 and 55 control the start of the late compressors. Additionally, if a failure occurs after the second compressor has started, the first unload relay 349 (FIG. 3c) and the second
The normally closed contacts 531 of the first safety relay 319 (FIG. 3a) feed directly to the second unload relay 361, respectively, or the second safety relay 32.
Through one normally closed contact 533, the failed compressor is commanded to be completely unloaded, ie, to return to the minimum vane position. In addition to unloading and shutting off the failed compressor, the failure shutoff circuit 220 also tells the controller 1 which compressor is the first compressor by means of a signal directed to the sequential circuit 216 (Figure 3b). to make sure that there is no malfunction.

For example, if the first compressor 2, previously assumed to be the lead compressor, fails, the first safety relay 319 will be de-energized and the normally closed contact 535 of the relay 319 (3b
) will return to the closed position. This is order relay 3
15 and 317, converting the second compressor 3 to the position of leading compressor in the manner previously described. In contrast, if the second compressor 3 fails, the second safety relay 321 is deenergized, causing its normally closed contacts 315 to close. This is the order relay 315 and 31
7, or causing de-excitation of switch 313. In this way, if the second compressor 3 fails, the first compressor 2 is designated as the first compressor. De-energization of relay 319 or 321 can also be performed by a fault indicator lamp 537 controlled by normally closed contact 539 of relay 319 or by normally closed contact 543 of relay 321.
is displayed to the user by a lamp 541 controlled by . In addition to converting a non-faulty compressor to a starter compressor, the fault shutoff circuit 220 prevents automatic restart of the entire system after the next system shutdown.

When a blockage occurs and a fault is indicated by de-energizing either relay 319 or 321, de-energizing pump start relay 361 closes its normally closed contact 543.
close it. This energizes the first unload relay 349 and the second unload relay 361, thereby preventing automatic energization of the first load relay 351 (the normally closed state of the now energized relay 349). Contact point 34
7) or prevent automatic energization of the second load relay 413 (normally closed contact 4 of relay 361
11). It can thus be seen that the load release signal has priority over the load signal. A system start switch 545 (FIG. 3a), typically a momentary contact switch, is provided to allow manual activation of pump start circuit 208. However, the normally open contacts 547 of the first safety relay 319, the normally open contacts 543 of the second safety relay 321, the normally closed contacts 357 of the energized first unload relay 349, and the normally open contacts 547 of the energized The normally closed contact 35 of the second unloading relay 361
9, if both compressors 2 and 3 fail,
Pump start relay 361 is connected to safety relays 319 and 32 by switch 421 (second safety relay 321) and switch 551 (first safety relay 319).
1 cannot be in the locked state until it is manually reset. Another typical refrigeration system failure that is detected and compensated for by the present invention is latecompressor false start, ie, the latecompressor does not start when it receives a start signal from the restriction device.

Some prior art controllers assume that the latecompressor has started when it actually does not. A false start of the latecompressor is detected by a normally closed bimetallic false start timer 553 (Figure 3c). During normal operation, recycle relay 410 is energized until the trailing compressor vanes are increased to a position sufficient to open the normally closed contacts of either vane switch 45 or 53. However, in the case of a false start, the recycle relay 4
1 remains excited forever. By setting the duration of false start timer 533 to a period longer than the period during which recycle relay 401 must be energized, false start allows timer 553 to expire, thereby causing its normal closure. Contact 555 opens and disconnects power to vane switches 43, 47, 51, and 53. As previously described, this causes a loss of power to the trailing compressor starting circuit, causing only the trailing compressor to continue operating. Start delay devices within the compressor used in such refrigeration systems cause the advance compressor to reach either vane switch 45 or 53 setpoint (typically maximum vane position) before contact 555 opens. 30%) is unloaded. Thus, the starter compressor begins to be loaded again on the next cycle of timer 200 on. If the demand for increased cooling again necessitates starting the trailing compressor, the vane switch 47 or 55 again energizes the trailing compressor start circuit 214 after the trailing compressor is ramped up. One of the other failures that sometimes occurs and can result in system overload damage is temperature controller failure.

If the temperature controllers (switches 37 and 3J9) are not in a condition to indicate a continuous demand for increased cooling, in effect allowing the controller 1 to transfer system control to the cold shutdown circuit 41. When the system has cooled down to a point where the controlled media is sufficient, the system will automatically shut down in the following order: The lead compressor is loaded to maximum capacity by the signal from the failed temperature control switch. When the advance compressor reaches maximum capacity, the load and unload circuit 206 or 218 unloads the advance compressor by energizing the appropriate unload relay 349 or 361. This is contact 357 or 359 (3a
), and the low temperature switch 41 is already open, so
Pump start relay 361 is de-energized. This includes normally closed contacts 557 of timer signal relay 309 and normally closed contacts 559 of pump start relay 361.
543, both unload relays 349 and 361
, thereby reducing the vane positions of both compressors to their minimum positions. The starter compressor also shuts down through its normally open contacts 379 when pump start relay 361 de-energizes. Due to the delays inherent in the typical compression used in such refrigeration systems, the trailing compressor will not start even if it receives a temporary start signal. This is because the vane positions of both compressors are such that vane switches 43 and 51 prevent the second compressor start relays 395 and 397 from entering the locked condition. In this way the entire system is shut off, thereby avoiding the problem of icing or other overload damage. Further, since contact 557 is controlled by timer signal relay 309, it is not allowed to attempt to restart until the next on cycle of timer 200, which prevents cycling. Contact 5 of pump start relay 361
59 and 543, along with contacts 557 of timer signal relay 309, place load and unload circuits 206 and 218 into unload mode in any system interruption in which safety relays 319 and 321 are energized, thereby causing compressor internal Note that it complements the load unloading circuit.
It should be seen. Manual set switches 559 and 561 are also provided for manual loading and unloading control of the first compressor 2 and the second compressor 3.

By installing the switches 313, 421, 551, 545, 559 and 561 at a location remote from the control device 1, remote manual control of the system is possible. Then the fourth
Attention is directed to Figures 3a-4e, which are schematic diagrams of logic gates for performing substantially the same functions as performed by the circuits illustrated in Figures 3a-3d.

Not shown in Figures 4a-4e are conventional analog-to-digital and digital-to-analog converters;
There are buffers necessary to convert the signals to suitable voltage levels for use in the control device 1 or the first and second compressors 2 or 3. The correspondence between the circuit elements of Figures 3a-3d and 4a-4e is such that the appropriate logic gates are given the same reference numerals as seen for the corresponding circuit elements shown in the relay embodiment of Figures 3a-3d. It is indicated by this. For example, the first safety latch 370 seen in Figure 4d is
Corresponds to the first safety relay 370 seen in the figure. To further aid in understanding the correspondence between the embodiments of Figures 4a-4d and the embodiments of Figures 3a-3d,
The logic gate embodiments of Figures a through 4d are shown in functional blocks as in Figure 2, with the signal sources for each block being named by the reference numbers assigned to the gates producing the respective signals. ing. For the particular elements shown in Figures 4a-4e, the first delay timer 45
Special attention should be given to the first, second delay timer 353, third delay timer 487, and fourth delay timer 469.

All four of these timers are ordinary one-shot timers with the same time width as their bimetallic counterparts, and are triggered on a positive transition. For timers 353 and 469, true (Q)
The output is taken from the output, and for timers 451 and 487, the output is taken from the sub-output O. The variable time width is provided by the use of a variable resistor within the one-shot RC time control circuit. Control timer 339 is again a variable time width one shot triggered by the positive crossing of the true (Q) output. Particular attention is drawn to the first safety latch 319 and the second safety latch 321 in FIG. 4d.

Both of these are conventional bimetal latch circuits with the output taken from the secondary (O) output line. In such a configuration, the reset line for latch 319 is provided by reset switch 551 and associated circuitry, and the reset line is provided by gates 319, 373 and 3.
is fed by an AND gate 701 with an input signal from 87. Similarly, for latch 321, the reset line is provided by switch 42 and associated logic as shown, and the set line is connected to AND gate 703 with input signals from gates 321, 419, and 427. It is supplied accordingly. The functions thus observed at the outputs of gates 319 and 321 are similar to their corresponding relays. Also note the solid state triggers 705 and 707 seen in Figure 4d.

These triggers are conventional solid state controllers and are triggered at typical logic levels to allow AC signals to reach terminals 15 and 31, respectively, at terminals 7 and 23, respectively. A fifth delay timer 373, a seventh delay timer 387, a ninth delay timer and an eleventh delay timer 7427, all shown in FIG. 4d, are triggered by a positive transition with a secondary output. This is a variable time width one-shot timer. The time width corresponds to the time width used for the corresponding bimetallic delay timer. A fourth diagram illustrating the solid-state counterparts of program motors 621 and 635.
Particular attention should be paid to figure e.

Since the program motors 621 and 635 are operated by time synchronization with the vane tilt motors of compressors 2 and 3, a conventional up-down counter can perform the same function as the program motors. The program counter 709 has a combinatorial sequential logic circuit 711 attached thereto.
together with the first program motor 621 and vane switches 43, 45, 47 and 49, and the second program counter 713 and its associated combinational sequential logic circuit 715 motor 635 and vane switch 51,
Replaces 53, 55 and 57. Program counters 709 and 713 are typically 8-bit up-down counters, with gate 717 providing the addable line, while gate 721 providing the subtractable line of counter 713, and gate 723 providing the subtractable line of counter 713. Supply subtractable. The clock of counter 709 is controlled by the appropriately buffered OR signals of terminals 17 and 19. The clock signal of counter 713 is supplied by the appropriately buffered OR signal of terminals 33 and 35. counter 7
The reset line of 09 is connected to the gate 360 as shown in the figure.
, 395 and 315. The reset line of counter 713 is controlled by a combination of signals from gates 360, 395 and 315 as shown. Combinatorial sequential logic circuits 711 and 715 have counters 709 and 713
For each type of count, output and latch circuits are provided, so that the combined use of counters 709 and 713 and their respective associated circuits 711 and 715 is provided by program motors 621 and 635 and their respective associated vane switches. Provides functionally the same open/close signals as

Additionally, three multi-position switches 733, 735 and 737 allow the user to set three different counts when supplied to terminals 11, 58, 62 and 66, respectively. Similarly, three multi-position switches 739, 741 and 743 provide three settings for the signals provided to terminals 27, 72, 76 and 80, respectively. Although the specific settings will vary depending on the rate at which the compressor changes capacity, typical settings for a machine that can reach maximum capacity within 3 [stocks] are: 5 and 6 seconds, 7 seconds for terminal 58, 8 seconds for terminals 62 and 68, and perhaps a fixed set of 2 hoes for terminal 68. Similar set values are used for terminals 27, 72, 76 and 80. Also note the first control latch 370 and the second control latch 372. These are conventional latches with the set line of the first latch 370 controlled by a suitably buffered converted signal from terminal 5, and its clear line from terminal 19. controlled by a converted signal that is buffered. Similarly, the buffered translated signals from terminals 21 and 35 control the set and clear lines of second control latch 372, respectively. Also solid state triggers 725, 727, 729 and 74
5 (Figure 4a) for triggers 705 and 707 (Figure 4d) as previously described. Also the fourth
A first delay line 747, a second delay line 749, a third delay line 751, and a fourth delay line 753 are shown in FIG. Each of these delay lines typically provides a time delay of 7 to 2 to allow temporary compressor failure to occur without signaling a system failure. The remaining logic gates are represented by conventional symbols and can be filled by positive logic techniques. FIG. 5 illustrates another specific example of the multi-compressor control device shown in FIGS. 1 to 4.

This embodiment uses a microprocessor, such as a Fairchild F8, to make the ordering and decisions. The inputs to the system are as described for the embodiment illustrated in Figures 3a-3d, however, the 110 port signals must be converted to logic signals that can be used by the microprocessor and associated circuitry. More specifically, the signal on line 754 is the first compressor C1
(not shown) indicates that the load is ready. A signal on line 755 indicates that the second compressor C2 (not shown) is ready for load. A signal on line 756 indicates that increased cooling is required from a room thermostat, clock, switch, or other suitable means. A signal on line 757 indicates that a reduction in cooling is required. lines 758 and 7
The signals at 59 direct the flow of water (or other coolant) in compressors C1 and C2, respectively. line 760a
The signals determine the leading and trailing compressors in the next operating cycle.

As before, manually operated switch 760b can override the incoming signal. Compressors C1 and C2
External load commands are directed on lines 761a and 762a, respectively, which are typically provided by manually operated switches 761b and 762b, respectively, or the like. Similarly, compressor C1
and commands to unload C2 are directed to lines 763a and 764a, respectively, by switches 763b and 764b, etc., respectively. Each of these eleven input signals is processed by a level shifter 765a-k so that each can be used to the logic level of the microprocessor 766 to which it supplies the signal.

Each level shifter also provides a signal to a conventional fault detection circuit 767a, which activates an indicator 767b, which may be of any suitable type, each time it detects a fault. Inputs also provided to the microprocessor 766 are a refrigerator fault reset switch 768 and switches 769a and 769b for manually starting compressors C1 and C2, respectively. The system reset switch V0 provides a signal to the microprocessor in the same way that the mode selector (automatic or manual) switch V1 does. A late compressor lockout switch JMoV2 and a recycle prevention switch JMoV3 also provide control signals to the microprocessor. Other inputs to microprocessor 766 are provided by a plurality of switches V4a-b. Switch JMo V4a has a minimum operating capacity of 32% ± 5%, for example, into the microprocessor.
Sets the percentage capacity that the compressor should be increased to upon startup. Switch JMo V4b selects the stabilization time (the off cycle of timer 200 in FIG. 2) between zero and nine minutes. Switch JMo V4c and 774d have compressors C1 and C2 in the micro processing device at 0%, respectively.
Used to set the exact time taken to progress from capacity to 100% capacity. That is, in the free running mode, the time to increase the vane angle from zero to 100% is measured and set in the machine at switches V4c and 774d. Typically less than 10@ is required for maximum blade change. Once the vane change time is set, it is easy to program the previously described incremental changes in loading and unloading into the microprocessor.

Using the microprocessor's internal clock as a time reference, the vane change time can be divided into any suitable fractional time. Incremental increases or decreases in capacity are accomplished by counting pulses of the microprocessor's time base until the desired incremental change is achieved.
The remaining switch inputs are the same as before.

The recycle prevention switch JMoV4e sets the time period during which the compressor will not restart if a shutdown occurs due to low demand for cooling to the microprocessor. The water flow fault switch JMoV4b sets the selected time for the compressor to start after receiving a start signal and before a fault condition is signaled to the microprocessor. Again with respect to using the microprocessor's internal clock as a time reference, the microprocessor's counting ability is dependent on the ability to start the latecompressor, shut off the latecompressor, reach maximum operating capacity, and the ability for system shutdown to occur. It should be recognized that internal sets are allowed.

If adjustment of any of these capabilities is desired, an additional input switch similar to the minimum vane set switch Model V4a can easily be provided. Micro processing device 766
The last remaining input to is provided by an external memory JMoV5 which stores information in the event of a system or compressor failure as directed by the microprocessor.

Memory JMoV5 thus signals the microprocessor not to attempt to start the failed compressor according to the guidelines discussed with respect to FIGS. 1-4. Because the memory is generally designed to leave information on system shutdown and provide that information on the next startup attempt, if you use erasable memory, a separate power supply (not shown) is required. ) must be established. If the microprocessor 766 has its input interrupted, it signals the respective compression through a buffer relay or the like, or causes the fault detection circuit 767a to detect a fault signal.

Power is applied to terminal 816 with a corresponding instruction device.
This activates the load timer 818 and also activates a capacity increase indicator such as a lamp or other suitable means displayed on a panel (not shown) visible to the user. When the load timer is energized, normally open contacts 82 attached to timer 806 and normally closed contacts 82 attached to panel fault relay 972.
5. Normally open contact 826 attached to load timer 818, normally closed contact 823 attached to vane boost relay 830, and finally normally closed contact 823 attached to maximum vane relay 834 (Figure 6b). The circuit is completed through contacts 832 to load relay 822. Load relay 822
energizes, the compressor start relay is connected through normally open (but now closed) contacts 838 attached to load relay 822 and normally closed contacts 844 attached to low load recycle relay 846. The circuit is completed at 836. When compressor start relay 836 is energized,
Contacts 848 associated therewith close and complete the circuit between terminals 850 and 852.

Terminal 850 is connected to the compressor's internal control and a signal from the compressor (not shown) is provided thereto when the compressor's internal starting circuit is enabled. Terminal 852 is connected to the compressor starting circuit, so terminal 85
A circuit completed between 0 and 852 starts the compressor. This is the indicating device 845 and the elapsed time indicating device 847.
Activate. Also, normally open contacts 849 attached to compressor start relay 836 are closed, and terminals 851 and 85 are closed.
Complete the circuit within 3 minutes and start the compressor pump. When the compressor starts, a controller within the compressor sends a signal so that the machine can load or reduce capacity (if no fault occurs). This signal is received by terminal 854, which energizes control relay 894, and terminal 855 is in neutral. This sends a signal to terminal 856 through normally open contacts 857 associated with relay 855, closed contacts 858 of deenergized minimum vane relay 860, and normally open contacts 859 of compressor start relay 836. Add. Also, when control relay 894 was energized, its associated contacts 894a indicated that the chiller was self-operating, i.e., if it was in operation, it was not being controlled by the panel. The indicating device 894b disappears. Indicator device 841a is also activated when a signal is applied to terminal 854, and another indicator device 841b is activated when a signal is applied to terminal 856. Terminal 856 is connected to a compressor vane angle control system in which signals from terminal 854 increase the compressor vane angle and capacity from a starting position of zero capacity to a set value. The amount of capacity increase is controlled by the load programmer 900 and associated circuitry that is activated when the compressor vane angle controller is activated. Load programmer 900 consists of a load programmer coil 901, an unload programmer coil 902, and contacts, one of which is illustrated in FIG. 6b. load programmer
900 is preferably a multi-position relay or solenoid activated switch. For example, a programmer can have two contacts designed to represent the full range of compression plate capabilities. Each contact in the programmer thus represents a 4% incremental increase in the compressor, the first contact represents O% capacity, and the last contact represents 100% capacity. Obviously, the number of contacts is a wide arbitrary matter, but a larger number of contacts generally increases accuracy. The current contact point of 2 sleeps, or 2? The increments of are chosen to give good accuracy without imparting undue cycling to the electromechanical embodiment. However, as previously noted, 2% increments may be used in microprocessor embodiments of the present invention. By energizing the load programmer coil 901, the programmer 90
0 selects contacts that represent an increase in compressive force. Similarly, a reduction in capacity is represented by energizing the unload programmer coil 902. In use, the time required for the programmer to move from one contact to the next is
It must approximately correspond to the time at which the blade angle represented by the programmer actually changes.

This is implemented in the following manner: Load increase signal (
When a signal (eg, applied to terminal 856) occurs, the circuit for energizing programmer timer 903 is completed.
This programmer timer is adjustable to a range up to fractional seconds. When timer 903 finishes timing, its associated normally open contact 904 closes. This is the same type of deprogramming timer 90 as timer 903.
5 and enable the load programmer-900. By adjusting programmer timer 903, programmer 900 can incrementally time the compressor blade angle at the same rate as it changes. When the compressor is first started, for example, each morning, the vane angle is typically set to a minimum capacity, such as % zero.

When the first capacity increase signal is received, the capacity is increased to an arbitrary initial starting level, for example 32%. 32%
Since the capacity is significantly greater than the one step increase (4% in this case), and as detailed later, Programmer-900
is generally allowed to increase (or decrease) by one step each cycle, so that the programmer and compressor can increase capacity up to the minimum starting level within a single cycle. , special circuits must be provided.

The increase to first start capability is achieved as follows.

When the first signal of capacity increase occurs, control relay 89
4 excites and closes its contacts 906. Closing of contact 906 allows program timer 903 to energize or begin timing while the compressor vane angle is set to normally closed contact 907 associated with deprogram timer 905, contact 906 and auxiliary minimum. A current path through normally closed contacts 908 associated with vane relay 865 allows the ramp to begin. Thus, while program timer 903 is in effect for one minute, the compressor blade angle is correspondingly increased by a signal from terminal 854 to terminal 856. When the programmer timer 903 completes its timing, its associated contact 904 closes and its . This energizes the program deprogram timer 905, which also energizes the normally closed contact 869 associated with the unload relay 874 and the auxiliary minimum vane relay.
Programmer load coil 901 is energized through contacts 909 attached to 865.

Only a momentary pulse is required to shift the programmer one step, so the programmer release timer 905 is set to terminate timing quickly, e.g., after one second of error. . When the program release timer 905 finishes timing, its associated contact 907 opens and the program release timer 905
Reset 03. This opens the contact 904 attached to the timer 903 and cuts off the current to the load coil 901 (
), and also the release timer
Reset 905. However, since the compressor vane angle has not yet reached the minimum starting position, there is still a current circuit to the programmer timer 903 due to the contacts 908 associated with the minimum vane relay 860.

This causes timer 903 to begin timing as before. Similarly, contact point 858 indicates that the compressor blade angle is terminal 8.
continues to be allowed to increase by the signal at 56. Thus programmer 900 continues to command incremental increases in capacity and the compressor blade angle continues to increase until minimum blade relay 860 is energized. This is programmer-9
00 are terminals A and B (illustrated in both Figures 6a and 6b)
Occurs when completing the circuit between. The programmer 900 preselects the stage 910 as the minimum vane position for starting (32% capacity in this example, or 8
When reaching the second stage), the signal at terminal A is transmitted through contact 910 to energize latch relay 862, which in turn energizes minimum vane relay 860 through contact 861. The normally open contacts 863 associated therewith are closed, thereby energizing the auxiliary minimum vane relay 865. This is the minimum blade contact point 85
8 and auxiliary minimum vane contact 908, thereby cutting off current to both programmer timer 903 and terminal 856. Thus, the programmer 900 and compressor will stop increasing when the minimum vane position is reached. Also, when the minimum vane relay 860 is energized, both it and the auxiliary minimum vane relay 865 are locked in the energized state through the minimum vane contact 864 and the contact 866 associated with the compressor start relay 836.

As will become clear later, the smallest blade relay 86
0 will therefore continue to energize until compressor start relay 836 is de-energized. This only occurs during system failure or normal shutdown. Both of these will be fully explained later. After the vane angle has been increased to the minimum position as described above, if the thermostat still indicates a need for increased cooling, a signal is applied to terminal 816 and the main portions of the process described above are repeated. That is, when the on-cycle timer 810 times the load timer 8
Power is applied to terminal 816 to excite 18. Load relay 822 is energized again. Compressor start relay
Since 836 remains energized by the first duty cycle, both the compressor and pump are starting. Completing the circuit between terminals 854 and 856, accomplished by normally open contacts 865 attached to the now energized load relay 822, applies an increasing signal to the compressor blade angle control. It will be done. However, because of the programmer timer 902, the vane angle is allowed to increase by one programmer step, or 4%. When the load relay 822 is energized, its associated contacts 91
0 causes the programmer timer 903 to start evening timing.

When the programmer timer 903 finishes timing, the contacts 904 associated with it close the load programmer coil 90.
1 to the normally open contact 9 attached to the load relay 822
11. Closing contact 904 initiates the timing of programmer release timer 905. However, when programmer timer 903 expires, its associated other normally open contacts close and energize vane incremental change relay 830.
Activation of relay 830 opens contacts 828 associated therewith, thereby deenergizing load relay 822.

When load relay 822 de-energizes, contacts 910 open and reset programmer timer 903.
This opens contact 904 and programmer release timer 9
Reset 06. Because of the timing of the release timer and the inherent rate at which such contacts open or de-energize, the programmer release timer must be reset well before it ends timing. Dew. In this way, programmers only increase by one step. Similarly, when load relay 822 is de-energized, its contacts 868 open and remove the signal from terminal 856. In this way, both the programmer 900 and the compressor vanes continue to increase. It should be noted that vane incremental relay 830, once energized, is locked into the energized state via its own contacts 913. This prevents cycling when the programmer timer is reset. If additional capacity increases are required, the process described above is repeated until the thermostat connected to terminal 816 indicates that no more increases are required.
Assume that the system is designed to have sufficient capacity to adequately cool the space for dispersed people, and that the thermostat indicates that no increase or decrease in capacity is required.

In such a case, the system is in balance and the indicating device 914 is in circuit through normally closed contacts 915 associated with load timer 818 and normally closed contacts 916 associated with unload timer 872. It will be activated accordingly. At some point, for example in the evening, the thermostat will notify terminal 87 that a reduction in capacity is required.
will indicate during the on cycle at 0.

This energizes the unload timer 872, lamp and unload indicator 874. When unload timer 872 is energized, normally open contact 876 associated with unload timer 872, normally closed contact 878 associated with relay 830, and normally open contact 878 associated with auxiliary minimum vane relay 865. The circuit is completed to the unload relay 874 through the normally open contact 873 attached to the zero percent position of the programmer 900 shown in FIG. 6b. When the unload relay 874 is energized, the normally open contacts 890 associated therewith close and the control relay
A normally open contact 892 attached to 894 completes the circuit between terminals 854 and 896, thereby signaling the compressor to decrease its vane angle and thus its capacity. Once again, programmer timer 903 and vane grading relay 830 cooperate to produce only gradual decrement. More specifically, when the unload timer is energized, its associated contact 917 closes and programmer timer 903 begins timing when it applies the unload signal to terminal 896. Programmer timer-903
When the timing ends, contact 904 closes and normally open contact 9 attached to unload relay 902
A signal is applied through 18 to the unload programmer coil 902. This signal causes the programmer 900 to taper off, but the taper is limited to only one step due to the load-like order. When programmer timer 903 finishes timing, contact 912 closes and vane grading relay 83 is then itself locked at contact 913.
Excite 0. Activation of relay 830 opens contacts 878, which energizes unload relay 874.

This opens contact 917, thereby resetting programmer timer 903. This causes the programmer to reset the reset timer 905 before the end of the timing,
A single step incremental reduction of both compressor blade angle and programmer 900 is then generated. The compressor capacity increases or decreases as required by the thermostat in the step sequence described above.

As cooling demand decreases, capacity decreases correspondingly.
At some point, the capacity of the compressor will be reduced to an arbitrarily low value, preferably below the minimum blade opening, such as 20% of the blade opening. When the capacity is so reduced, latching relay 930 (Fig. 6b) is energized and its associated normally open contact 932 (Fig. 6a) opens (latching relay 862 is activated by the programmer when the starting capacity is below the minimum starting capacity). Step 93
Note that it is released when it is tapered down to 1). These include the normally closed contact 803 of the fault timer 842, the normally closed contact 805 associated with the anti-recycle timer 936, the normally open contact 938 associated with the minimum vane relay, and the normally closed lockout switch 939. to complete the circuit from terminal 800 to low load recycle relay 845. This completed circuit energizes the low load recycle relay 846, illuminates the low load indicator 940, and starts the timing of the recycle prevention timer 936. Ru. Recycling relay 846 is itself locked by normally open contact 942 which shunts contacts 938 and 932. When recycle relay 846 is energized, its associated normally closed contact 844 opens and de-energizes compressor start relay 836.

This shuts off both the compressor and compressor pump due to loss of signal at terminals 852 and 83. The system thus stops cooling in response to loss of demand. The compressor is unloaded to the zero capacity by the normally closed contact 919 attached to the next relay 836, which causes the zero capacity contact 886 of the programmer 900 to unload the zero capacity relay 874.
Programmer-900 and terminal 8 until the circuit to
96 (from terminal 920 and contact 921 attached to control relay 846). When the recycling prevention timer 936 completes its timing,
The system is allowed to sense demand again through the thermostat.

The recycle prevention timer 936 preferably has a timing cycle that can vary between 0 and 6 cycles to allow stabilization of the temperature of the space being cooled. contact 805 opens and recycle relay 84
Cut off the circuit to 6. Upon de-energization of recycle relay 846, the system returns to the starting condition described above and is permitted to sense the thermostat in the manner described above. ``This mode of recycling can be prevented simply by opening the recycling lockout switch 939. Similar to the multiple compressor controller previously described, the single compressor controller shown in Figures 6a and 6b also incorporates various fault finding circuits and safety devices. One such circuit is the panel failure timer 841, which is preferably an adjustable timer with up to six cycles. Load relay 8
22 and unload relay 874 are energized, panel fault timer 842 provides timing through either load timer 818 or unload timer 872. As previously noted, load timer 818
is energized in response to the cooling demand of the thermostat at terminal 816, which closes the normally open contact 940 associated therewith. If the compressor start relay 836 is not yet energized, the panel failure timer will activate the normally closed contact 9 attached to the compressor start relay 836.
54 and a normally closed contact 952 associated with compressor start relay 836.

If the start relay 836 is energized, the panel fault timer 842 activates the contacts 950, the normally closed contacts 956 associated with the load relay 822, and the unload relay 874.
Timing is initiated through a normally closed contact 958 associated with . If an unload signal is received at terminal 870 from the thermostat, unload timer 872 is activated. A normally open contact 960 associated therewith and connected in series to contact 950 is connected to the panel fault timer.
842 closes to start timing. The normally closed contacts 955 attached to the smallest vane relay 860 are
Ensure that compressor start relay 836 is properly energized. Once the panel fault timer 8.42 begins timing, either the load relay 822 or the unload relay 874 is activated before the panel fault timer finishes timing or if the compressor is prevented from increasing its load capacity. must be excited before it can be activated. This of course only occurs in the event of a panel failure. Upon initial startup, the compressor start relay must also be energized to open contacts 952. In normal operation, timer 842
when load relay 822 is energized and contacts 956 open, or when unload relay 847 is energized and contacts 958 open.
will be reset when it opens. If either load relay 822 or unload 872 does not reset panel failure timer 842 before it expires, the normally open contact 9 associated with timer 842
70 closes and energizes panel fault relay 972 and fault indicator 974.

Similarly, normally closed contact 9 attached to timer 842
76 opens, and then the system ``in operation'' indicator 97
8 and the indicating device 979 which is extinguished by the panel fault relay contact 922. When the panel fault relay is energized, its associated contacts 980 close and lock the panel fault timer 842. This causes contact 840 to open and de-energizes compressor start relay 836, thereby increasing the compressor blade angle despite requests for increased capacity from the thermostat for control relay contact 857. prevent. Once the panel fault relay is energized, compressor capacity increases are prevented, but the compressor is connected between panel fault relay contacts 982 (connected between terminals 850 and 852) and 984 (terminals 851 and 853).
(connected between) allows it to continue operating at the same capacity.

The compressor is allowed to reduce capacity by a controller internal to the compressor that overrides the controller when panel fault relay 972 is energized. Momentary contact switch 9 that manually energizes load relay 822 and unload relay 874, respectively, thereby overriding automatic control of the system when start switch 802 is used in manual mode.
86 and 988 are provided.

It should be noted that in case of system failure, the system is shut down without unloading the programmer 900. In this way, the load capacity at the time of failure can be obtained as a diagnostic means. As an operational aid, an indicator 988 can also be provided to indicate working load capacity.
Although the above description of a single compressor controller embodying the present invention dealt with a substantially electromechanical system, this system is illustrated in FIGS. 4a-4e and 5 for a two-compressor system. It can be easily implemented in a solid state system as shown. Although the present invention has been described in detail above, it is to be understood that the invention is not limited to the details set forth above, but that the invention extends to the full scope of the following claims.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a refrigeration system control device that uses two compressors, Figure 2 is a block diagram showing the connection with the device in Figure 1, and Figures 3a to 3d are control systems that use relays. Schematic diagram of the device, Fig. 3 is Fig. 3a to Fig. 3d
4a to 4e are schematic diagrams of a control device using logic gates; FIG. 5 is a schematic diagram of a control device using a microprocessor; FIGS. 6a to 6b The figure is a circuit diagram of a control device used for an individual compressor. 2 and 3 are compressors, 1 is a control device, 5, 7, 9
, 13, 15, 17, 19, 21, 23, 25
, 29, 31, 33, and 35 are terminals, 37, 39 are temperature control switches, 200 is a timer, 202, 204 are transfer circuits, and 206, 218 are load and unload circuits.

Claims (1)

[Claims] 1. Incrementally increasing the refrigeration capacity of at least one variable capacity compressor, which is used to control the temperature of the medium and can be connected to temperature sensing means for measuring the temperature of the medium, which generates an output. a refrigeration system controller for varying the capacity of the variable capacity compressor by a predetermined increment, and means for generating a predetermined periodic on and off signal that is shorter than the on time of the periodic signal; timing means for providing a signal having a period corresponding to the time required to cause the temperature to change; and timing means adapted to be connected to said timing means and said temperature sensing means so as to be responsive to a change in temperature and from said periodic signal generating means; a first load for changing the capacity of the at least one compressor by an increment defined by the timing means in response to the signal from the temperature sensing means only during the on portion of the signal; The device characterized in that it is provided with load unloading means. 2. The apparatus of claim 1, wherein the capacity range of said variable capacity compressor is divided into at least 25 said increments. 3. A patent comprising means for increasing the capacity of said variable capacity compressor to a minimum starting capacity upon receiving from said temperature sensing means a first signal requesting an increase in capacity during the on portion of said periodic signal. Apparatus according to claim 1. 4. After the refrigerating capacity of the variable capacity compressor has been reduced to a predetermined low level, even if during the on portion of the periodic signal there is a signal from the temperature sensing means indicating a need for increased refrigerating capacity. means for preventing said first loading and unloading means from responding to a signal from said temperature sensing means indicating a need for an increase in refrigeration capacity for a predetermined period of time The apparatus of claim 1, 2, or 3. 5. Fault detection for detecting a fault in the control device or the compressor and, if a fault is detected, preventing the loading and unloading means from attempting to increase the capacity of the compressor. 4. A device according to claim 1, 2 or 3, comprising means. 6 said timing means having a total timing sequence substantially equal to, but mechanically independent of, the time required to continuously change the capacity of said compressor from a minimum setting to a maximum setting; 2. The apparatus of claim 1 for generating a predetermined number of timing signals representative of the actual capacity of the compressor. 7. The apparatus of claim 6, wherein said timing means is a program motor and a vane switch. 8. The apparatus of claim 6, wherein said timing means is a counter. 9 suitable for connection to said temperature sensing means and for controlling the capacity of said second compressor to said timing means in response to a signal from said temperature sensing means during an on portion of a signal from said periodic signal generating means; second loading and unloading means for varying the signal by a second increment thus defined; and said first loading and unloading means during the on-portion of the signal from said periodic signal generating means; refrigeration system according to claim 1 for controlling two variable capacity compressors, comprising transfer means for automatically activating either said second loading and unloading means. Control device. 10. The apparatus according to claim 9, wherein the transfer means alternately changes the capacity between the first compressor and the second compressor. 11. A refrigeration system controller for use with two variable capacity compressors, suitable for connection to a first timing signal means for generating periodic on and off signals and a temperature sensing means; and a first loading and unloading for automatically generating a signal for changing the capacity of the first compressor in response to the signal from the temperature sensing means during the ON signal of the first timing signal. and second timing signal means for generating a predetermined time period in response to said signals from said first loading and unloading means, said second timing signal having first and second states. timing signal means, suitable for connection to the temperature sensing means and for varying the capacity of the second compressor in response to a signal from the temperature sensing means during an on signal of the first timing signal; a second loading and unloading means for automatically generating a signal; and a third means for generating a second predetermined period in response to said signal from said second loading and unloading means. said third timing means having first and second states as a timing signal; and in response to signals from said second and third timing signal means, an on signal of said first timing signal means. a first transfer means for automatically activating either the first loading and unloading means or the second loading and unloading means; means is activated only when said third timing signal means is in a first predetermined state; said second loading and unloading means is activated only when said third timing signal means is in a first predetermined state;
and wherein the predetermined period of time corresponds to the time required to change the capacity of each of the compressors by a predetermined increment. 12 fourth timing signal means activated by said first loading and unloading means and having first and second states; and fourth timing signal means activated by said second loading and unloading means. , and in response to signals from said fourth and fifth timing signal means having first and second states, said during the on signal of said first timing signal means. a second transfer means for automatically activating either the first loading and unloading means or the second loading and unloading means, the first loading and unloading means said fifth timing signal means is activated only when said fourth timing signal means is in a first predetermined state; said second loading and unloading means is activated only when said fourth timing signal means is in a first predetermined state; The second timing signal means is activated only at certain times, and the second timing signal means is activated only when the first loading and unloading means generates a signal increasing the capacity of the first compressor; The third timing signal means is the second timing signal means.
is activated only when the loading and unloading means generates a signal that increases the capacity of the second compressor, and the fourth timing signal means is activated only when the first loading and unloading means generates a signal that increases the capacity of the second compressor. The fifth timing signal means is activated only when the second loading and unloading means generates a signal that reduces the capacity of the second compressor. 12. The device of claim 11, which is activated only when an occurrence occurs. 13 a first for generating a system pump start signal in response to the signal generated by the first loading and unloading means for increasing the capacity of the first compressor;
and a second compressor pump start signal for generating a compressor pump start signal in response to the signal generated by the second loading and unloading means for increasing the capacity of the second compressor. 13. Apparatus according to claim 12, comprising the means of: 14. The apparatus of claim 13 further comprising means for generating a first compressor start signal in response to said signal generated by said compressor pump start means. 15 means for detecting and generating a signal when said first compressor is operating at a predetermined maximum load; and said second compressor in response to said signal from said maximum load signal means; Claim 1 further comprising means for generating a signal for starting the compressor.
Apparatus in Section 4. 16 generating, in response to the first compressor maximum load signal, a first signal for causing the first loading and unloading means to generate a signal for reducing the capacity of the first compressor; and a second means for generating a signal to the second loading and unloading means for reducing the capacity of the second compressor in response to the first compressor maximum load signal. 16. The apparatus of claim 15, further comprising means for generating a signal. 17. first means for terminating the capacity reduction signal to the first loading and unloading means when the first compressor reaches a predetermined capacity; and
When the compressor reaches a predetermined capacity, the second compressor
17. The apparatus of claim 16, further comprising second means for terminating said capacity increase signal to said loading and unloading means. 18 having a first and a second state, selecting the first compressor as a lead compressor and the second compressor as a trailing compressor when in the first state, and selecting the second compressor as a trailing compressor;
further comprising sequencing means for selecting the second compressor as a leading compressor and the first compressor as a trailing compressor when the trailing compressor is started; 12. The apparatus of claim 11, wherein the apparatus is started and loaded to maximum capacity before being used. 19 means for sensing the capacity of the first compressor, the program motor being adapted to vary the capacity of the first compressor in response to signals generated by the first loading and unloading means; and means for detecting the capacity of the second compressor, the sensing means comprising: sensing means for sensing the capacity of the second compressor, the sensing means comprising: sensing means for sensing the capacity of the second compressor; 18. The apparatus of claim 17, further comprising said sensing means including a program motor for varying the capability of said sensing means. 20. The apparatus of claim 19, wherein said capacity sensing means is adapted to additionally respond to unloading signals generated by said first and second compressors. 21 first sensing means for detecting a failure of one of said compressors and then generating a signal; and for cutting off power from said failed compressor in response to a signal from said first sensing means. a first lockout means of the first lockout means;
Claims 11, 17 or 18 further comprising second lockout means for preventing restart of the remaining compressor after system shutdown in response to a signal from the lockout means of the compressor. Device. 22. When the respective loading and unloading means receives the first signal for increasing capacity from the temperature sensing means during the ON portion of the periodic signal, the respective capacity of the variable capacity compressor is reduced to a minimum. 12. The apparatus of claim 11 further comprising means for increasing starting capability. 23. Claim 23, wherein the transfer means is adapted to cause the first compressor to receive all loading and unloading signals until the capacity of the first compressor increases to a predetermined maximum value. Control device according to clause 22. 24. said transfer means reaches said predetermined maximum capacity by reducing the capacity of said first compressor to a predetermined level and increasing the capacity of said second compressor to a minimum starting level; 24. The apparatus of claim 23, adapted to be responsive to said first compressor. 25. After the capacity of both said compressors has been reduced to a predetermined low level, even if a signal indicating a need for increased refrigeration capacity from said temperature sensing means is present during the on-portion of said periodic signal. Also, for a predetermined period of time,
12. The apparatus of claim 11 further comprising means for preventing said first and second loading and unloading means from responding to said signal from said temperature sensing means. 26. The apparatus of claim 25, wherein the second compressor is caused to cease cooling when its capacity is reduced below a minimum low level.