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US3768545A - Temperature control system with multiple thermostats - Google Patents

Temperature control system with multiple thermostats Download PDF

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Publication number
US3768545A
US3768545A US00271087A US3768545DA US3768545A US 3768545 A US3768545 A US 3768545A US 00271087 A US00271087 A US 00271087A US 3768545D A US3768545D A US 3768545DA US 3768545 A US3768545 A US 3768545A
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signal
temperature
circuit
regulating
reference signal
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F Wills
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York International Corp
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Borg Warner Corp
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Assigned to YORK INTERNATIONAL CORPORATION, 631 SOUTH RICHLAND AVENUE, YORK, PA 17403, A CORP. OF DE reassignment YORK INTERNATIONAL CORPORATION, 631 SOUTH RICHLAND AVENUE, YORK, PA 17403, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BORG-WARNER CORPORATION
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1927—Control of temperature characterised by the use of electric means using a plurality of sensors
    • G05D23/1928—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperature of one space
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1927—Control of temperature characterised by the use of electric means using a plurality of sensors
    • G05D23/193—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces
    • G05D23/1935—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces using sequential control
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/07—Details of compressors or related parts
    • F25B2400/075—Details of compressors or related parts with parallel compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/02—Compressor control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2501—Bypass valves

Definitions

  • a heating-cooling control system includes thermostats [21] Appl No: 271,087 in the discharge and return air passages, and a temperature set dial. A selection clrcuit energizes one of the thermostats below a preset temperature, and the other [52] U.S.Cl 165/27, 236/91, 307/39 thermostat is energized above that temperature. A [51] Int. Cl alone F251) 29/00 heat override circuit prevents a call for heat above a [58] Field 01 Search 165/14, 22, 26, 27; certain temperature.
  • Another important consideration of the invention is to provide a multiple compressor system in which the first compressor energized is not cycled on and off, but delayed in its re-energization, to obviate excess cycling.
  • Still another important consideration of the invention is the provision of a system which regulates energization and de-energization of the first compressor, loading and unloading of the first compressor, energization and deenergization of a second compressor, and second compressor loading and unloading, in the appropriate sequence to minimize excessive drain in the electrical supply circuit.
  • a control arrangement constructed in accordance with this invention is useful to regulate operation of a cooling system which discharges air into a space and receives return'air from that space.
  • the control arrangement comprises a first thermostat disposed to provide a first temperature signal indicative of the discharge air temperature, and a second thermostat disposed to provide a second temperature signal indicative of the return air temperature.
  • An adjustable temperature set unit provides a set signal indicating the desired temperature of the space.
  • a selection circuit is connected to receive both the set signal and a first reference signal. This selection circuit completes an operating circuit for the first thermostat when the value of the set signal is less than the value of the first reference signal, and completes an operating circuit for the second thermostat when the value of the set signal is greater than the value of the first reference signal.
  • a comparator circuit is connected to receive both the set signal and the temperature signal from the energized thermostat, and to provide a regulating signal, related to the difference between the set signal and the temperature signal from the energized thermostat, to regulate associated heating and/or cooling equipment.
  • such an arrangement when used with at least two compressors, includes a first time-delay circuit to prevent re-energization of the first compressor for a minimum time after the regulating signal decreases and the first cooling control stage indicates the first compressor should be taken off the line.
  • a second time-delay circuit coupled to the second cooling control stage which governs the second compressor, delays the energization of the second compressor when the regulating signal indicates a call for additional cooling, to prevent simultaneous energization of the compressors and a consequent high demand upon the electrical supply circuit.
  • FIG. 1 is a block diagram, partly in schematic form, depicting the general arrangement of a portion of this invention
  • FIG. 2 is a schematic diagram which sets out circuit details of components shown generally in FIG. 1;
  • FIG. 3 is a schematic diagram which depicts the remainder of the control arrangement of the invention.
  • FIG. 1 shows a general system layout of a portion of the control arrangement of this invention.
  • Conventional equipment such as a compressor and hot gas conduits utilized in regulating the cooling, and coils or other units for effecting the heating, are not depicted. Similarly the actual discharge and return air vents or conduits are not shown.
  • Such components are well known and can be located in many environments, such as a railroad box car, truck, stationary enclosure, or any other space to be cooled and/or heated by this systern.
  • FIG. 1 shows a first thermostat 11 disposed to provide a first temperature signal which indicates the discharge air temperature.
  • a second thermostat 10 is positioned to provide a second temperature signal which indicates the return air temperature. Both temperature signals do not appear on line 12 simultaneously, because selection circuit 13 completes an operating circuit for only one of the first or second thermostats, so that only one temperature indicating signal appears on line 12 at any one time.
  • a temperature set unit 14, which can be a simple potentiometer or other device, provides a temperature set signal on line 15 and, over line 16, to selection circuit 13. The selection circuit also receives a first reference signal over line 17. When the value of the set signal is less than the value of the first reference signal, an operating circuit is completed over line 20 for first thermostat 11.
  • an operating circuit is completed over line 18 for return air thermostat 10.
  • This arrangement facilitates the establishment of a crossover point or reference temperature by the value of the reference signal passed over line 17 to selection circuit 13.
  • this reference signal can be set to represent a temperature of 32F.
  • selection circuit l3 completes an energizing circuit over line 18 for return air thermostat l0, and allows this thermostat to do the controlling.
  • the temperature set unit 14 is adjusted to call for a temperature below the crossover point indicated by the signal on line 17, then the energizing signal is provided on line 20 so that the discharge air thermostat 11 does the controlling.
  • Comparator circuit 21 is connected to receive both the set signal, over lines and 22, and the temperature signal, over line 12, from whichever one of thermostats 10, 11 is then energized by selection circuit 13.
  • the comparator stage provides an output or regulating signal on line 23 which is related to the difference between the set signal on line 22 and the temperature signal on line 12.
  • This regulating signal is passed over line 24 and common line 25 to the cooling control stages, to be described below in connection with FIG. 3.
  • the regulating signal is also passed from line 25 over resistors 26 and 27, and line 28 to the heating control circuitry, which will also be described in connection with FIG. 3.
  • a heat override circuit 30 is provided, and has one input connection which receives a second reference signal over line 31.
  • This second reference signal is usually of a different value then the level of the first reference signal supplied over line 17 to the selection circuit.
  • the level of the second reference signal establishes a base against which the temperature set signal, also received by override circuit 30 from line 15, is compared to provide a lock-out signal on output conductor 32.
  • the amplitude of the reference signal on line 31 can be selected to represent a temperature of F.
  • a voltage divider arrangement 35 is shown connected between an energizing conductor 36 and a plane of reference potential, commonly designated ground.
  • Resistors 37-43 are connected in series betweenconductor 36 and ground to establish different voltage levels or reference'signals, utilized to signify different temperature levels against which the actual temperature signals and the set point signal can be compared, and against which the regulating signal applied to the cooling and heating control stages can be referenced.
  • Conductors 44-50, inclusive, are individually connected to different circuit points in the voltage divider 35 as shown to establish voltage levels, or reference signals, connoting different temperature levels.
  • Another reference unit or voltage divider arrangement 51 includes resistors 52, 53 and 54 connected in series between conductors 47 and 50.
  • Conductor 17 is connected to the junction of resistors 53 and 54, and is also coupled over resistor 55 to one input connection of an operational amplifier 56, connected as a voltage level detector in the thermostat selection circuit 13.
  • Temperature set unit 14 is a potentiometer having its end connections coupled to conductors 47 and 50.
  • the other input connection of op amp 56 receives the temperature set signal from the movable tap of potentiometer 14, over conductor 15, resistor 57 and conductor 16.
  • the pin 4 connection of this op amp is grounded, and its 8 pin connection is coupled to conductor 36, or B+.
  • Selection circuit 13 also includes three NPN type transistors 58 60 and 61.
  • the output connection of op amp 56 is coupled over a resistor 62 to input connection 3, and the output connection is also coupled to conductor 63.
  • the base of transistor 58 is coupled to the common connection between resistors 64 and 65, which resistors are coupled in series between conductor 63 and ground.
  • the emitter of transistor 58 is grounded and its collector is coupled to the common connection between resistor 66 and the anode of diode 67.
  • the other end of resistor 66 is coupled to energizing conductor 36, and the cathode of diode 67 is coupled to the base of transistor 61.
  • the base of transistor 60 is coupled over diode 68 and resistor 70 to conductor 63.
  • the emitters of transistors 60, 61 are both connected to conductor 50, and the collectors of these two transistors are respectively coupled over conductors 18, 20 to the return and discharge thermostats 10, 11.
  • the symbol T on these thermostats indicate a Thermistor is employed in the preferred embodiment of this circuit.
  • the other connection of each Thermistor is coupled to conductor 12, and a resistor 71 is connected between conductors 12 and 47 to provide a return circuit for whichever one of Thermistors l0, 1 l is energized by circuit 13.
  • the value of the first reference signal on line 17 represents a temperature of 32F. It is further assumed that the temperature called for by set unit 14 is below 32, and under these conditions it is desired to regulate the system with an output signal from discharge air thermostat 11. At this time the output signal from stage 56 is low, and there is no gate drive to transistor 60 to complete an operating circuit for Thermistor 10. However current flows from energizing conductor 36 over resistor 66 and diode 67 to the base of the transistor 61, driving this transistor on and completing an operating circuit'for the discharge air thermostat 11. Thus under these conditions the temperature signal from Thermistor 11 is passed over line 12 and resistor 72 to the 6 input connection of comparator circuit 21.
  • transistor 58 As transistor 58 conducts it provides a virtual ground at the anode of diode 67, which robs transistor 61 of the gate drive previously received.
  • transition in control from one thermostat to the other, can be achieved at any desired temperature by changing the level of the first reference signal provided on line 17.
  • Comparator circuit 21 receives the set signal over conductor 15, resistor 73 and conductor 22 at its 5 input terminal. This comparator circuit also receives the temperature-indicating signal, over line 12 and resistor 72, from the energized Thermistor. The output connection 7 of this stage is coupled over resistor 74 to a common connection 75. A regulating signal is provided from point 75 over conductor 24 to the associated control circuits to be described in connection with FIG. 3. A Zener Diode 76 is coupled between connection 75 and ground. Capacitor 77 is coupled in parallel with resistor 78, and this parallel circuit is coupled between terminal 75 and input connection 6 of comparator stage 21. The comparator stage operates in a well known manner to provide the regulating signal on conductor 24 and common line 25 as a function of the difference between the set signal received at input connection 5 and the temperature signal received at its other input connection 6.
  • heat override stage 30 also comprises an op amp. Its 6 input connection is coupled over a resistor 80 to conductor 31, over which the second reference signal is received. The other input connection 5 is coupled over a resistor 81 to conductor 15,
  • a capacitor 82 is coupled between the two input terminals, and a resistor 83 is coupled between the 5 input connection and the output connection 7, which output connection is also coupled to line 32.
  • This stage 30 functions as the heat override circuit, to provide a lock-nut signal on line 32 to prevent operation of the heat equipment when the temperature called for by the set signal on line is below the value of the temperature represented by the second reference signal on line 31.
  • the regulating signal is received over line 24 and distributed over common conductor 25.
  • the signal from heat override stage 30 is received over conductor 32.
  • Conductors 44-49, inclusive, are connected as already described to the difierent voltage points in the voltage divider-or reference arrangement 35, to pro-' vide different reference signals to the control stages in FIG. 3.
  • the op amps 85, 86, 87 and 88 are connected as cooling control stages to operate or switch in succession and provide actuating output signals to bring on additional cooling as the level of the regulating signal on common line 25 first exceeds that on line 48, then exceeds the level of the reference signal on line 46, next exceeds the reference signal on line 45, and finally is greater than the level of the reference signal established on conductor 44.
  • the other op amp, 90 is a heating control stage used to provide an actuating output signal to associated heating equipment to bring on the heat. In that there is only one heat control stage, this will first be described.
  • a capacitor 91 is coupled between energizing conductor 36 and the common connection between resistors 26, 27 in the input circuit of op amp 90.
  • the other input connection 3 of this stage is coupled over resistor 92 and conductor 49 to the voltage divider arrangement, to receive a reference signal as already described.
  • a capacitor 93 is connected between the input terminals, and a resistor 94 is coupled between the output terminal 1 and the input connection 3 of this op amp.
  • the regulating signal on line 25 is applied to the input terminal 2, and the reference signal from conductor 49 is passed to the other input connection 3.
  • op amp switches and provides a higher or positive output signal at connection 1, which is passed over resistor 95 to rapidly drive on NPN type transistor 96.
  • Conduction of transistor 96 provides an output signal on conductor 97 to actuate the associated heating equipment.
  • this signal can operate a heat controlling relay to pass electrical current through heating coils and provide heat to the enclosed space regulated by the control system of this invention.
  • diode 98 is connected between its collector and emitter as shown, and resistor 100 is coupled between its base and emitter. The emitter, one end of resistor 100, and the anode of diode 98 are connected to ground.
  • the regulating signal on common line 25 is passed over resistor 101 to the 3 input connection of this stage.
  • Capacitor 102 is coupled between the input connections.
  • the reference signal supplied over line 48 is passed over resistor 103 to input connection 2.
  • the output terminal 1 of this op amp is coupled over resistor 104 to input connection 3.
  • op amp 85 switches to provide a positive or high actuating output signal on conductor 105, which signal is passed over resistor 106 to the base of another NPN type transistor 107.
  • This transistor is gated on to energize the first unit of cooling capacity.
  • this signal can complete the energizing circuit for the coil of a relay which puts the first of two compressors on the line, to initiate cooling of the controlled space.
  • the circuit of transistor 107 includes a diode 108 and a resistor 110, connected in a manner similar to diode 98 and resistor 100 in the circuit of transistor 96.
  • an important feature of this invention is a provision of an off time-delay circuit including a field-effect transistor (FET) 111.
  • FET field-effect transistor
  • energizing conductor 36 is coupled over a resistor 112 to the source of this transistor, and three high-ohm resistors 113, 114 and 115 are coupled in' series between conductor 36 and the upper plate of capacitor 116.
  • a table of actual circuit components is set out at the end of the specification, but for the present it is sufficient to note that these three resistors provide a very high value of resistance between conductor 36 and capacitor 116.
  • the lower plate of this capacitor is coupled over conductors 117 and 118 to the output side of op amp 85, which must go high and provide a positive signal to bring on the first compressor again.
  • Another capacitor 120 is coupled between conductor 36 and a common circuit connection 121, with diode 122 coupled as shown between circuit point 121 and the source of PET 111. The drain of thistransistor is grounded.
  • Another diode 123 also provides a reference connection between the heating circuit and common circuit point 121, which is also coupled to the 2 input connection of op amp 85.
  • the first call for cooling which provided the high or positive output signal from op amp 85, was applied over conductors 118 and 117 to the lower plate of capacitor 116.
  • This signal allowed the capacitor 116 to be charged from conductor 36 over resistor 112, the source and gate of FET 111, and resistor 124 to the upper plate of capacitor 116.
  • the entire B+ voltage which was 24 volts positive on line 36 in a preferred embodiment, is developed across capacitor 116 as the first compressor is brought on the line.
  • op amp 85 switches to a low output signal, this in effect provides a ground or low level signal at the bottom plate of capacitor 1 16.
  • this lower plate is now at minus B voltage, but the other side of capacitor 116 is returned through a very high resistance (113-115) to line 36.
  • the timing circuit including FET l1 1 was set to provide approximately a 3- minute off interval of compressor number one. With this circuit the repeated turn-on of the first compressor in the cooling system is prevented, saving undue wear which might otherwise be caused as the regulating signal on common line 25 changed back and forth at a level very close to the reference signal on line 48.
  • transistor 130 was gated on as the positive signal from op amp 85 was passed over line 118, resistor 132 and conductor 133 to the base of transistor 130. Another resistor 134 is coupled between the base and emitter of this transistor, and the diode 135 is con nected as shown between the collectorand emitter to protect transistor 130. Conduction of transistor 130 provides a signal on line 131 to energize the hot gas controlling relay, or any other suitable capacity control arrangement. This assumes a system in which the bypass of hot gas to the suction side of the compressor is utilized.
  • op amp 86 will be switched to provide an output signal over line 125, resistor 126, and though resistor 127 to ground.
  • the voltage developed across resistor 127 provides a signal to the gate of transistor 128 which rapidly drives this transistor on and virtually grounds the base of transistor 130, to cut off this transistor and deenergize the hot gas controlling relay or whatever other hot gas control component may be connected to conductor 131.
  • capacitor 136 is coupled between its input terminals.
  • Input connection 6 receives a reference signal over resistor 137, and the other input connection is coupled over resistor 138 to common conductor 25, to receive the analog regulating signal.
  • Resistor 140 is coupled between output connection 7 and input connection 5, and diode 141 is coupled between input connection 6 and conductor 142 to the on-time delay circuit for the second compressor.
  • op amp 87 is switched to provide a high output signal at its terminal 7.
  • This amplifier stage has a capacitor 143 connected between its input terminals, and input connection 6 receives the reference signal over resistor 144.
  • the regulating signal on common line 25 is coupled over resistor 145 to the other input connection, which is also coupled over resistor 146 to output terminal 7.
  • a diode 147 has its anode connected to the common connection between resistors 145 and 146 and capacitor 143, and its cathode coupled to conductor 118.
  • this signal is extended over conductor 148 to the emitter of a'PNP type transistor 150.
  • this circuit includes another FET transistor 151 connected to provide a minimum on-delay, so that the second compressor cannot be energized by a signal of a step function type and an amplitude sufficient to bring on compressors one and two at the same time.
  • the source of unit 151 is coupled over resistor 152 to conductor 148, and the gate of the transistor is coupled to the common connection between a very high resistance 153 and the upper plate of a capacitor 154, the lower plate of which is grounded.
  • the upper end of resistor 153 is coupled to conductor 148.
  • the drain of PET 151 is coupled through a resistor 155 to ground.
  • Another resistor 156 is coupled between conductor 148 and the common connection between resistor 155 and the drain of FET 151.
  • the source of this transistor is coupled to the base of transistor 150, which has its collector coupled through a series circuit including resistors 157 and 158 to ground.
  • NPN type transistor has its emitter grounded and its base coupled to the common connection between resistors 157 and 158.
  • the collector of this transistor 160 is coupled over line 161 to provide another actuating output signal for bringing the second compressor on the line, as by completing a relayenergizing circuit for this compressor.
  • a diode 162 is coupled between the base and emitter of transistor 160 forcircuit protection.
  • the resistances in the voltage divider circuit including FET 151 are selected so that the potential at the source of this unit is very close to the full B voltagefor this circuit as received over conductor 148.
  • Resistor 156 is sized electrically to have a value considerably less than the resistance of resistor 152. Accordingly the voltage at the drain of PET 1511 is considerably lower than the voltage at its source. Thus even though the signal on line 48 is raised when cooling control stage 87 is switched, the voltage applied to the base of PNP type transistor 150 is not changed appreciably at this time, in that the voltage at the drain of FET 151 remains close to ground.
  • this circuit functions as an inverse of the timing circuit including FET 111.
  • This on-time delay circuit prevents simultaneous energization of the compressors to obviate a large drain on the electrical supply, which could blow a fuse or even damage equipment of the motorgenerator type which has a limited electrical capacity.
  • the last cooling stage including op amp 88 is operated when the level of the regulating signal on common line 25 passed over resistor 163 to the 3 input connection of this op amp exceeds the level of the reference signal passed over conductor 44 and resistor 164 to the 2 input connection.
  • a capacitor 165 is coupled between the input connections of this stage, and a resistor 166 is coupled between output connection 1 and input connection 3.
  • the actuating output signal is passed over resistor 168 to the common connection between resistors 126 and 127, to regulate the hot gas or other capacity control arrangement.
  • op amp 87 is switched on to initiate the timing interval so that after FET 151 conducts, transistors 150 and 160 are driven on to bring the second compressor on the line.
  • a signal is extended from output pin 7 over resistor 146, diode 147, and resistor 132 to energize transistor 130 and bring the hot gas relay on.
  • op amp 88 is switched to provide a signal over line 167 and resistor 168 to drive on transistor 128, turn off transistor 130, and shut off the hot gas.
  • the value of the reference signal on line 49 is established so that as op amp 90 is switched, and the heat brought on, when the temperature in the controlled space is one degree F. below that established by the temperature set unit 14.
  • a control arrangement for regulating operation of a cooling system which discharges air into a space and receives return air from the space comprises:
  • a first thermostat disposed to provide a temperature signal indicative of the discharge air temperature
  • a second thermostat disposed to provide a second temperature signal indicative of the return air temperature
  • a temperature set unit adjustable to provide a set signal indicating the desired temperature of the space
  • a selection circuit connected to receive both the set signal and a first reference signal, which selection circuit completes an operating circuit for the first thermostat when the value of the set signal is less than the value of the first reference signal, and completes an operating circuit for the second thermostat when the value of the set signal is greater than the value of the first reference signal;
  • a comparator circuit connected to receive both the set signal and the temperature signal from the energized one of the thermostats, and to provide a regulating signal, related to the difference between the set signal and the temperature signal from the energized thermostat, to regulate associated equipment.
  • a control arrangement for regulating operation of a cooling system which discharges air into a space and receives return air from the space comprises:
  • a first Thermistor disposed to provide a first tempe rature signal indicative of the discharge air temperature
  • a second Thermistor disposedto provide a second temperature signal indicative of the return air temperature
  • a temperature set potentiometer adjustable to provide a set signal indicating the desired temperature of the space
  • a selection circuit including a voltage level detector connected to receive both the set signal and a first reference signal, a first transistor connected to complete an operating circuit for the first Thermistor when the value of the set signal is less than the value of the first reference signal, and a second transistor connected to complete an operating circuit for the second Thermistor when the value of the set signal is greater than the value of the first reference signal; and
  • a comparator circuit connected to receive both the set signal and the temperature signal from the energized one of the Thermistors, and to provide a regulating signal, related to the difference between the set signal and the temperature signal from the energized Thermistor, to regulate associated equipment.
  • a control arrangement for regulating operation of a cooling system which discharges air into a space and receives return air from the same space, including first and second thermostats disposed to provide temperature signals indicating the discharge and return air temperature, a temperature set unit providing a set signal to indicate the desired space temperature, a selection circuit completing an operating circuitto only one of the thermostats as a function of the set signal and a first reference signal, a comparator circuit receiving the set signal and the temperature signal from the energized thermostat to provide on a common line a regulating signal which is a function of the difference between the set signal and the actual temperature signal from the energized thermostat, and at least two cooling control stages, each having an input portion coupled to the common line, and each having an output circuit individually coupled to different cooling components, to bring on one of the different cooling components at different amplitude levels of the regulating signal on the common line.
  • a first cooling control stage having a first input connection coupled to the common line and a second input connection connected to receive a first reference signal, to provide an actuating output signal when the regulating signal exceeds the first reference signal and bring the first compressor on the line;
  • a second cooling control stage having a first input connection coupled to the common line and a second input connection coupled to receive a second reference signal, to provide an actuating output signal when the regulating signal exceeds the second reference signal and bring the second compressor on the line;
  • a first time-delay circuit coupled to said first cooling control stage, effective to maintain said first controlling stage in the off condition for a predetermined minimum time interval after the regulating signal on the common line has decreased below the value of the first reference signal, to avoid excess cycling of the first compressor.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Remote Sensing (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
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US00271087A 1972-07-12 1972-07-12 Temperature control system with multiple thermostats Expired - Lifetime US3768545A (en)

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US27108772A 1972-07-12 1972-07-12

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AU (1) AU473506B2 (it)
CA (1) CA1003531A (it)
DE (1) DE2334508B2 (it)
FR (1) FR2192280B1 (it)
GB (1) GB1414417A (it)
IT (1) IT992618B (it)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949807A (en) * 1974-08-30 1976-04-13 Robertshaw Controls Company Air conditioning system with integral energy conserving elements
US4042875A (en) * 1974-10-25 1977-08-16 U.S. Philips Corporation Temperature transducer arrangement which supplies threshold voltages with the aid of a single sensor
US4138607A (en) * 1977-06-24 1979-02-06 Pako Corporation Dual priority temperature control
US4138627A (en) * 1975-09-02 1979-02-06 Hughey And Phillips, Inc. Current-level-sensitive switching system
US4156455A (en) * 1975-07-04 1979-05-29 Der Meulen Theo Van Method and apparatus for controlling a heat transfer installation
US4236084A (en) * 1978-10-26 1980-11-25 Gingras Richard P Apparatus and method for in-line energization and de-energization of external loads in series with an external source of electricity in response to externally sensed parameters
US4323112A (en) * 1979-03-06 1982-04-06 Mark Controls Corporation No energy band temperature control
US4333519A (en) * 1980-05-08 1982-06-08 Doron Shafrir Controller for air conditioning units, heating units and the like
EP0060724A2 (en) * 1981-03-17 1982-09-22 Sea Containers Limited Cargo refrigeration
US4353409A (en) * 1979-12-26 1982-10-12 The Trane Company Apparatus and method for controlling a variable air volume temperature conditioning system
US4429829A (en) 1981-11-20 1984-02-07 Mallinckrodt, Incorporated Interactive dual probe temperature control system
US4538672A (en) * 1982-07-02 1985-09-03 Conoco Inc. Tracking temperature controller apparatus
US4694890A (en) * 1985-04-15 1987-09-22 Dianalog Systems, Inc. Analog computer variable duty modulator
EP0495464A2 (en) * 1991-01-15 1992-07-22 Thermo King Corporation Refrigeration temperature control system
US5971068A (en) * 1996-02-02 1999-10-26 Toshiba Kikai Kabushiki Kaisha Method and system for temperature control of hydraulic oil
US6176306B1 (en) 1997-07-01 2001-01-23 Robert Gault Method and device for controlling operation of heat pump
US6538552B2 (en) * 1999-12-28 2003-03-25 Itw Industrial Components S.R.L. Thermostat, in particular for electric household appliances
US20140202449A1 (en) * 2010-10-04 2014-07-24 Global Solar Water And Power Systems, Inc. Multiplatform heating ventilation and air conditioning control system
US20160223219A1 (en) * 2013-08-30 2016-08-04 James Leych Lau Energy saving controller
US20170102157A1 (en) * 2015-10-09 2017-04-13 General Electric Company Air conditioner units and methods for determining indoor room temperatures
US10808961B2 (en) 2013-08-30 2020-10-20 James Leych Lau Energy saving controller

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES439087A1 (es) * 1975-07-02 1977-03-01 Peter Wolfwenderoth Perfeccionamientos introducidos en sistemas de regulacion detemperatura.
US4067203A (en) * 1976-09-07 1978-01-10 Emerson Electric Co. Control system for maximizing the efficiency of an evaporator coil
JPS5934012B2 (ja) * 1979-04-26 1984-08-20 松下電器産業株式会社 時間制御装置
JPS58200973A (ja) * 1982-05-20 1983-11-22 三菱重工業株式会社 加熱及び冷却用冷凍装置の温度制御装置
GB2136988B (en) * 1983-03-16 1987-05-13 Pixel Plus Limited Central heating boiler control unit
DE3326977C2 (de) * 1983-07-27 1987-03-26 Bruno 7441 Wolfschlugen Kümmerle Kühlaggregat für elektrische Schaltschränke
GB2151815A (en) * 1983-12-19 1985-07-24 Bernard Joseph Jelley An electronic switching device fitted to boilers to save fuel
US4549403A (en) * 1984-04-06 1985-10-29 Carrier Corporation Method and control system for protecting an evaporator in a refrigeration system against freezeups
KR900002143B1 (ko) * 1985-03-29 1990-04-02 미쯔비시 덴끼 가부시기가이샤 덕트식 멀티조온 공조시스템

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2602591A (en) * 1948-11-15 1952-07-08 Honeywell Regulator Co Condition control apparatus
US2689932A (en) * 1947-08-02 1954-09-21 Bailey Meter Co Balanceable network electric measuring system
US3144991A (en) * 1963-02-05 1964-08-18 Henry F Marchant Hot water heating system having a wide range temperature equalizer control
US3292689A (en) * 1964-07-07 1966-12-20 Kimurakoki Co Ltd Platefin-type heat exchanger and method of making same
US3500898A (en) * 1968-08-26 1970-03-17 Borg Warner Control system for multi-stage heating and cooling system
US3612165A (en) * 1968-11-12 1971-10-12 Gulton Europ Ltd Temperature controllers
US3616846A (en) * 1969-11-17 1971-11-02 Borg Warner Control system for heating and/or cooling system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2689932A (en) * 1947-08-02 1954-09-21 Bailey Meter Co Balanceable network electric measuring system
US2602591A (en) * 1948-11-15 1952-07-08 Honeywell Regulator Co Condition control apparatus
US3144991A (en) * 1963-02-05 1964-08-18 Henry F Marchant Hot water heating system having a wide range temperature equalizer control
US3292689A (en) * 1964-07-07 1966-12-20 Kimurakoki Co Ltd Platefin-type heat exchanger and method of making same
US3500898A (en) * 1968-08-26 1970-03-17 Borg Warner Control system for multi-stage heating and cooling system
US3612165A (en) * 1968-11-12 1971-10-12 Gulton Europ Ltd Temperature controllers
US3616846A (en) * 1969-11-17 1971-11-02 Borg Warner Control system for heating and/or cooling system

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949807A (en) * 1974-08-30 1976-04-13 Robertshaw Controls Company Air conditioning system with integral energy conserving elements
US4042875A (en) * 1974-10-25 1977-08-16 U.S. Philips Corporation Temperature transducer arrangement which supplies threshold voltages with the aid of a single sensor
US4156455A (en) * 1975-07-04 1979-05-29 Der Meulen Theo Van Method and apparatus for controlling a heat transfer installation
US4138627A (en) * 1975-09-02 1979-02-06 Hughey And Phillips, Inc. Current-level-sensitive switching system
US4138607A (en) * 1977-06-24 1979-02-06 Pako Corporation Dual priority temperature control
US4236084A (en) * 1978-10-26 1980-11-25 Gingras Richard P Apparatus and method for in-line energization and de-energization of external loads in series with an external source of electricity in response to externally sensed parameters
US4323112A (en) * 1979-03-06 1982-04-06 Mark Controls Corporation No energy band temperature control
US4353409A (en) * 1979-12-26 1982-10-12 The Trane Company Apparatus and method for controlling a variable air volume temperature conditioning system
US4333519A (en) * 1980-05-08 1982-06-08 Doron Shafrir Controller for air conditioning units, heating units and the like
EP0060724A2 (en) * 1981-03-17 1982-09-22 Sea Containers Limited Cargo refrigeration
EP0060724A3 (en) * 1981-03-17 1982-12-22 Sea Containers Limited Cargo refrigeration
US4429829A (en) 1981-11-20 1984-02-07 Mallinckrodt, Incorporated Interactive dual probe temperature control system
US4538672A (en) * 1982-07-02 1985-09-03 Conoco Inc. Tracking temperature controller apparatus
US4694890A (en) * 1985-04-15 1987-09-22 Dianalog Systems, Inc. Analog computer variable duty modulator
EP0495464A2 (en) * 1991-01-15 1992-07-22 Thermo King Corporation Refrigeration temperature control system
EP0495464A3 (en) * 1991-01-15 1993-05-05 Thermo King Corporation Refrigeration temperature control system
US5971068A (en) * 1996-02-02 1999-10-26 Toshiba Kikai Kabushiki Kaisha Method and system for temperature control of hydraulic oil
US6176306B1 (en) 1997-07-01 2001-01-23 Robert Gault Method and device for controlling operation of heat pump
US6538552B2 (en) * 1999-12-28 2003-03-25 Itw Industrial Components S.R.L. Thermostat, in particular for electric household appliances
US20140202449A1 (en) * 2010-10-04 2014-07-24 Global Solar Water And Power Systems, Inc. Multiplatform heating ventilation and air conditioning control system
US20160223219A1 (en) * 2013-08-30 2016-08-04 James Leych Lau Energy saving controller
US20170051936A1 (en) * 2013-08-30 2017-02-23 James Leych Lau Energy saving controller
US10066849B2 (en) * 2013-08-30 2018-09-04 James Leych Lau Energy saving controller
US10119719B2 (en) * 2013-08-30 2018-11-06 James Leych Lau Energy saving controller
US10808961B2 (en) 2013-08-30 2020-10-20 James Leych Lau Energy saving controller
US20170102157A1 (en) * 2015-10-09 2017-04-13 General Electric Company Air conditioner units and methods for determining indoor room temperatures

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Publication number Publication date
GB1414417A (en) 1975-11-19
JPS4952342A (it) 1974-05-21
DE2334508B2 (de) 1979-03-29
JPS5631493B2 (it) 1981-07-22
IT992618B (it) 1975-09-30
AU473506B2 (en) 1976-06-24
AU5623473A (en) 1974-12-05
DE2334508A1 (de) 1974-01-24
FR2192280A1 (it) 1974-02-08
FR2192280B1 (it) 1976-04-30
CA1003531A (en) 1977-01-11

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