CN105526773A - Control device and control method of refrigerated storage - Google Patents

Abstract

The present invention provides a control device and a control method for a cooling room, which can keep the temperature inside the room constant by performing constant control of the temperature inside the room by PID control during constant temperature cooling, and can prevent the growth of frost in the evaporator, which can reduce the need for cooling. The frequency of defrosting and extending the defrosting cycle time. In the internal temperature constant control, the heat supply process of opening the expansion valve for a predetermined heat supply time to enter the heat supply state and the heat shutoff process of closing the expansion valve for a predetermined heat shutoff time are alternately repeated. .

Description

Cooling storage control device and control method

technical field

The present invention relates to a control device and a control method for a cooling room which are installed in a cooling room such as a freezer counter or a refrigerated counter in a store, and which suppress frosting on an evaporator of the cooling room and prevent a decrease in cooling capacity.

Background technique

In shops such as supermarkets and convenience stores, counters such as freezer counters and refrigerated counters for displaying products in a frozen or refrigerated state are used.

As shown in FIG. 1 , this counter 30 has a display rack 32 for displaying goods, an air outlet 34 for blowing cold air to the display rack, and a fan 38 that sucks the air in the display rack and circulates the sucked air in the counter 30 The suction port 36.

In addition, in the counter 30, a general refrigerating cycle is used, and it is provided with: a pipe 12 through which the refrigerant flows; and the evaporator 16 which absorbs the heat of the circulating air and cools it by changing the state of the refrigerant from liquid to gas.

In addition, when such a counter is installed in a store, although not shown in the figure, a refrigerator equipped with a compressor and a condenser is installed outdoors, and a plurality of counters are used in a state connected to one refrigerator. More, among them, the above-mentioned compressor compresses the gas refrigerant coming out of the evaporator to make it into a high-temperature and high-pressure gas refrigerant, and the above-mentioned condenser releases heat from the high-temperature and high-pressure gas refrigerant discharged from the compressor to become a liquid refrigerant . However, there are also cases where one refrigerator is connected to only one counter and used.

A counter where the refrigerator is separately installed outside the house is called an individually installed counter. On the other hand, there is also a counter in which a refrigerator part such as a compressor or a condenser is integrated, and such a counter is called a built-in freezer counter or a built-in counter.

The cooling room such as the counter 30 has a control device 22, and the lighting 26, the fan 38, the defrosting heater 24, the dew prevention heater, the expansion valve 14 (temperature regulating valve) and the like included in the counter are controlled by the control device 22 .

In the case of using a mechanical expansion valve that automatically adjusts the degree of superheat by the temperature sensing cylinder and the pressure inside the pipe as the expansion valve 14 of the counter 30, an electromagnetic valve for supplying liquid is provided in front of the expansion valve 14 (refrigerator side). The electromagnetic valve is controlled by the control device 22 to switch heat supply and heat cutoff, and to adjust the temperature in the refrigerator.

In addition, there is also a cooling room configured as follows. That is, a valve opening control output unit for controlling the valve opening of the expansion valve 14 is provided in the control device 22, and a high-durability solenoid valve or an electronic expansion valve is used as the expansion valve 14. The device 22 controls the valve opening of the expansion valve 14 .

There is also a cooling room in which a solenoid valve for liquid supply is provided in front of the expansion valve 14 (refrigerator side) in the case of a configuration using a high-durability solenoid valve or an electronic expansion valve as the expansion valve 14, and is controlled by The device 22 controls the electromagnetic valve for supplying the liquid to switch the heat supply and heat cutoff, and while the temperature adjustment of the temperature in the refrigerator is performed through the supply cutoff control, the control device 22 is used to adjust the heat supply through the superheat control, the constant temperature control in the refrigerator, etc. The valve opening of the expansion valve 14. However, when a high-durability solenoid valve or an electronic expansion valve with a valve closing function is used as the expansion valve 14, the expansion valve 14 functions as a liquid supply solenoid valve, and the liquid supply solenoid valve is often omitted.

As a superheat detection unit for detecting the degree of superheat in the evaporator 16, the control device 22 includes an inlet pipe temperature sensor 18 for detecting the temperature of the refrigerant on the inlet side of the evaporator and a temperature sensor 18 for detecting the temperature of the refrigerant on the outlet side of the evaporator. The outlet piping temperature sensor 20 of the temperature, and, as the interior temperature detection unit for detecting the interior temperature, the control device 22 has the air outlet temperature sensor 40 which detects the temperature of the air outlet 34 and the suction pipe which detects the temperature of the suction port 36. Mouth temperature sensor 42.

In addition, the control device 22 may be configured to use both the air outlet temperature detected by the air outlet temperature sensor 40 and the inlet temperature detected by the inlet temperature sensor 42, and to regard their intermediate temperature as the temperature in the storage room, or , It can also be configured such that only one of the temperature sensors is used, and the temperature detected by the temperature sensor plus the value after compensation is regarded as the temperature in the refrigerator.

In addition, only one of the temperature sensors may be used, and the temperature detected by the air outlet temperature sensor may be used as the interior temperature, or the temperature detected by the suction inlet temperature sensor may be used as the interior temperature. In such a case where the interior temperature is obtained using only one of the temperature sensors, it is not necessary to provide both the air outlet temperature sensor and the suction inlet temperature sensor, and only the temperature sensor on the used side may be provided.

In the counter 30 configured in this way, ON/OFF control is used to switch between the heat supply state in which the refrigerant flows into the evaporator 16 and the heat cut-off state in which the refrigerant does not flow into the evaporator 16. The control device 22 adjusts the valve opening of the expansion valve 14 to change the flow rate of the refrigerant to control the cooling capacity, thereby adjusting the internal temperature of the counter 30 .

As cooling control methods for adjusting the valve opening of the expansion valve 14 , a method of controlling based on the degree of superheat (superheat degree control) and a method of controlling based on the interior temperature (constant interior temperature control) are known.

In addition, superheat degree control and interior temperature constant control are performed by the PID control of the microcomputer mounted in the control apparatus 22. FIG. Such PID control includes position-type PID control and speed-type PID control, but in this specification, the case of speed-type PID control will be described.

In the degree of superheat control, the valve opening of the expansion valve 14 is adjusted so that the degree of superheat approaches a predetermined set value of the degree of superheat.

When the superheat degree is controlled by the speed type PID control, the proportional component of the control output is the output of reducing the valve opening degree when the superheat degree decreases (the change amount of the superheat degree is negative), and when the superheat degree increases ( The variation of superheat is positive) is the output of increasing the valve opening.

The degree of superheat uses a value obtained by subtracting the temperature of the refrigerant on the inlet side of the evaporator 16 (evaporation temperature) from the temperature of the refrigerant on the outlet side of the evaporator 16 (return pipe temperature), and is configured, for example, by The controller 22 calculates the evaporation temperature detected by the inlet pipe temperature sensor 18 and the return pipe temperature detected by the outlet pipe temperature sensor 20 .

In addition, when a pressure sensor (not shown) for detecting the pressure of the refrigerant in the pipe 12 is provided instead of the inlet pipe temperature sensor 18, and the low pressure can be detected, the low pressure can also be converted into the saturation temperature. The value obtained by subtracting the evaporation temperature from the return pipe temperature detected by the outlet pipe temperature sensor 20 was used as the degree of superheat.

In addition, in the interior temperature constant control, the valve opening degree of the expansion valve 14 is adjusted so that the interior temperature approaches a predetermined interior temperature set value.

When the internal temperature constant control is also performed by speed-type PID control, the proportional component of the control output decreases when the internal temperature decreases (the amount of change in the internal temperature is negative) similarly to the superheat control. Valve opening, and increase the output of the valve opening when the temperature in the storage increases (the variation of the temperature in the storage is positive).

In addition, the control system used for the control device adopts PID control using an electronic expansion valve and a high-durability solenoid valve as in Cited Document 1, but does not use an electronic expansion valve or a high-durability solenoid valve. In the control device of the storage, the internal temperature of the storage is adjusted by turning ON/OFF the electromagnetic valve for supplying liquid installed on the upstream side of the mechanical expansion valve.

Patent Document 1: JP-A-59-185948

Patent Document 2: Japanese Patent Laid-Open No. 2008-209016

However, there are two stages in the cooling of the counter 30, one is when the cooling of the counter is started for the first time, and the cooling is started after the defrosting is completed. One is pull-down cooling to set the internal temperature, and the other is constant temperature cooling to maintain the internal temperature at a specified temperature.

In particular, counters 30 installed in stores etc. are cooled at a constant temperature for a long period of time. At this time, the refrigerant flows into the evaporator 16, and the temperature of the evaporator 16 is 0° C. or lower. Therefore, moisture or the like in the atmosphere adheres to the evaporator 16, thereby generating frost.

If the frost adheres to the evaporator 16, the cooling capacity will be reduced, and such frost will continue to grow, and eventually the evaporator 16 will be in a state where air cannot be ventilated, and the interior of the refrigerator cannot be cooled, resulting in an increase in the interior temperature. In the case of heavy frost, it may be necessary to stop the cooling, take out the products displayed on the counter, and manually remove the frost adhering to the evaporator 16 .

Therefore, the evaporator 16 is provided with a defrost heater 24 for removing the generated frost, and the power supply of the defrost heater 24 is periodically turned on to melt the frost and perform defrosting (defrosting). Such defrosting is called heater defrosting.

On the other hand, in a counter having a relatively high set temperature without defrosting heater 24 in evaporator 16, the refrigerant does not flow into evaporator 16 to perform defrosting (defrosting). Such defrosting is called aperiodic defrosting.

In the ON/OFF control that switches between the heat supply state in which the refrigerant flows into the evaporator 16 and the heat cut state in which the refrigerant does not flow into the evaporator 16, the internal temperature is controlled by controlling the refrigerant inflow or non-inflow, so the internal temperature It fluctuates according to the amount of the difference (differential) between the ON point and the OFF point.

On the other hand, as in the control cited in Document 1, in the method of PID control of the expansion valve to adjust the internal temperature, not only the binary control of ON/OFF, but also the valve opening in the middle, so the relationship between ON/OFF Compared with OFF control, the temperature change in the chamber can be reduced.

However, since the refrigerant does not flow into the state, there is no non-periodic defrosting effect, which contributes to frosting on the evaporator 1 .

Therefore, in the method of adjusting the interior temperature by performing PID control on the expansion valve, the time interval (defrost cycle time) that must be defrosted is short, and the frequency that must be defrosted becomes high. If the defrosting is performed at the same time interval as in the ON/OFF control, it is considered that the evaporator 16 will be in a state where air cannot be ventilated, resulting in poor cooling. Furthermore, in the case of a counter used in a store such as a supermarket or a convenience store, it becomes a big problem if the counter becomes poorly cooled during business hours.

Contents of the invention

In the present invention, in view of such current situation, it is an object to provide constant temperature control in the refrigerator by PID control during constant temperature cooling, so that the temperature in the refrigerator can be kept constant, and the growth of frost in the evaporator can be prevented, which can reduce the undesired temperature. The frequency of non-defrosting, the control device and control method of the cooling storage for extending the defrosting cycle time.

The control device and control method of the cooling room of the present invention use a high-durability solenoid valve or an electronic expansion valve as an expansion valve, and control the valve opening degree by the control device.

Specifically, the control device of the cooling room of the present invention has at least piping through which the refrigerant flows, an expansion valve that is installed on the piping and converts the liquid refrigerant condensed by the condenser into a low-temperature and low-pressure liquid refrigerant, and makes the refrigerant A control device for controlling the valve opening of the expansion valve in a cooling store of an evaporator in which the state of the agent is changed from liquid to gas to absorb the heat of circulating air and cooled, and is characterized in that

The control device stores a predetermined heat supply time when the refrigerant flows in the evaporator and a predetermined heat cut-off time when the refrigerant does not flow in the evaporator,

In the interior temperature constant control, the heat supply step of opening the expansion valve for the heat supply time for the heat supply state and the heat cut-off step of closing the expansion valve for the heat cut-off time for the heat cut-off state are alternately repeated. .

In this case, the above-mentioned control device may be configured to store a preset switching determination time,

When the switching judging time has elapsed since the start of cooling, it is judged that the frosting amount of the evaporator exceeds a predetermined threshold, and the heat supply time and the heat cut-off time stored in the control device are changed to predetermined values,

Preferably, the ratio of the heat cutoff time to the heat supply time is greater after the switching determination time elapses than before the switching determination time elapses.

In addition, the control method of the refrigerator of the present invention is at least provided with piping through which the refrigerant flows, an expansion valve installed on the piping and converting the liquid refrigerant condensed by the condenser into a low-temperature and low-pressure liquid refrigerant, and making the state of the refrigerant A control method for controlling the valve opening of the above-mentioned expansion valve in a cooling store of an evaporator cooled by absorbing heat of circulating air by changing liquid into gas, characterized in that,

In the internal temperature constant control, the heat supply process of opening the expansion valve for a predetermined heat supply time to enter the heat supply state and the heat supply process of closing the expansion valve for a predetermined heat interruption time to enter the heat cut state are alternately repeated. Cutting process.

At this time, when the preset switching determination time can pass from the start of cooling, it is determined that the frosting amount of the evaporator exceeds a predetermined threshold, and the heat supply time and the heat cut-off time stored in the control device are changed. for the specified value.

In addition, it is preferable that the ratio of the heat cutoff time to the heat supply time is greater after the switching determination time elapses than before the switching determination time elapses.

According to the present invention, by forcibly shutting off the heat during the constant internal temperature control, frosting on the evaporator can be suppressed, the internal temperature can be stably maintained by the internal temperature constant control, and the defrosting cycle can be extended, even in the following Even when defrosting is performed at the same time interval as in ON/OFF control, cooling failure due to frosting will not occur, and a highly reliable cooling room can be provided.

Description of drawings

FIG. 1 is a schematic configuration diagram for explaining the structure of a counter equipped with a control device.

FIG. 2 is a schematic configuration diagram for explaining the configuration of the control device of the present embodiment.

FIG. 3 is a flowchart for explaining the flow of thermal shutdown control in the control device of the present embodiment.

In the figure: 12—piping, 14—expansion valve, 16—evaporator, 18—inlet piping temperature sensor, 20—outlet piping temperature sensor, 22—control device, 24—defrosting heater, 30—counter, 32—display Frame, 34—air outlet, 36—suction inlet, 38—suction fan, 40—air outlet temperature sensor, 42—suction inlet temperature sensor, 50—microcomputer, 52—power input terminal, 54—temperature sensor input terminal, 56 —control output terminal, 58—communication terminal, 60—display unit.

detailed description

Hereinafter, embodiments (examples) of the present invention will be described in more detail based on the drawings.

In addition, the structure of the counter 30 provided with the control device 22 in this Example is basically the same structure as the above-mentioned conventional counter 30.

FIG. 2 is a schematic configuration diagram for explaining the configuration of the control device 22 of the present embodiment.

The control device 22 includes a microcomputer 50 for performing arithmetic processing of PID control, etc., a power input terminal 52 for receiving operating power, a temperature sensor input terminal 54 for inputting temperature signals from the temperature sensors 18 , 20 , 40 , and 42 , And a control output terminal 56 for outputting control signals to the expansion valve 14 , the fan 38 , the defrosting heater 24 , and the lighting 26 .

In addition, for example, a communication terminal 58 and a display unit 60 can also be provided, wherein the communication terminal 58 is used to communicate with a higher-level control device (not shown) that collectively controls a plurality of counters 30, refrigerators, etc., and the display unit 60 It is used to display the temperature detected by each temperature sensor 18, 20, 40, 42, the state of the expansion valve 14, and the like.

The control device 22 of this embodiment is configured to control the expansion valve 14 by constant internal temperature control during constant temperature cooling, and alternately repeat opening the expansion valve 14 for a predetermined heat supply time during the constant internal temperature control to generate heat. A heat supply step in a supply state, and a heat cutoff step in which the expansion valve 14 is closed for a predetermined heat cutoff time to enter a heat cutoff state.

In addition, in order to set the thermal cut-off state by the control device 22, the valve opening of the expansion valve 14 is set to 0% to close the valve, or when using a non-closing expansion valve, it is also possible to replace the non-closing expansion valve. In addition, for example, a closable valve (not shown) such as a liquid supply solenoid valve is provided in the piping 12 , and the control device 22 closes the closable valve so as to set it in a heat cut-off state.

In this way, by alternately repeating the heat supply process and the heat cut-off process during the constant internal temperature control, the internal temperature can be maintained stably, and the defrosting cycle can be extended, at the same time interval as in the ON/OFF control. Even when defrosting is performed, there will be no cooling failure caused by frosting. In addition, in this specification, the time which alternately repeats a heat supply process and a heat cut-off process is called a defrosting cycle time.

In addition, as will be described later, based on the frosting tendency depending on the type and size of the counter 30, it may be estimated that the amount of frosting exceeds a predetermined threshold after a predetermined switching determination time passes, and the heat supply time and the heat cut-off time may be changed to predetermined values. value.

In addition, in the present embodiment, the amount of frosting on the evaporator 16 is estimated according to the switching determination time, but it may also be configured such that the amount of frosting on the evaporator 16 is measured on the surface of the evaporator 16 using an optical sensor such as a photosensor or a digital camera. For example, in order to detect the air volume passing through the evaporator 16, an air volume sensor can be installed before and after the evaporator 16. When the air volume passing through the evaporator 16 is less than the specified air volume value, it can be inferred that the evaporator 16 is frosted. amount exceeds the specified threshold.

In addition, since the degree of superheat of the evaporator 16 is almost constant during the constant temperature control in the refrigerator, the degree of superheat of the evaporator 16 may be monitored. exceeds the specified threshold.

Hereinafter, thermal shutdown control by the control device 22 of the present embodiment will be described based on the flowchart shown in FIG. 3 .

In the present embodiment, when the cooling of the counter 30 is started, the control device 22 executes heat cutoff control at predetermined intervals (S10).

First, it is determined whether the control device 22 is under superheat degree control or internal temperature constant control (S20). Then, when it is determined that the superheat degree control is being performed, the heat cut control is directly terminated (S110).

On the other hand, when it is determined that the internal temperature constant control is in progress, it is determined whether or not the preset switching determination time A has elapsed from the start of cooling (S30), and the heat supply time and the heat cut-off time are set according to the elapsed time. .

When the switching determination time A has not elapsed, the heat supply time is set to the set value b, and the heat cut-off time is set to the set value c (S40).

On the other hand, when the switching determination time A has elapsed, the heat supply time is set to the set value d, and the heat cut-off time is set to the set value e (S50).

In addition, the switching judgment time A is a setting value used for judging the first half and the second half of the defrosting cycle, and may be a preset defrosting cycle time according to the type or size of the counter 30, for example, half, may be at Change appropriately in the defrost cycle time.

In addition, it is preferable that the set value c and the set value e which are the heat cut-off time be short enough that the internal temperature does not rise so much.

On the other hand, as the set value b and the set value d of the heat supply time, it is preferable that the time is longer than the set value c and the set value e for cooling the inside of the refrigerator.

In addition, there is a tendency for frost to form on the evaporator 16 more easily in the second half of the defrost cycle than in the first half of the defrost cycle. Therefore, it is preferable to set the ratio of the heat cut-off time to the heat supply time to be larger in the second half of the defrosting cycle than in the first half of the defrosting cycle.

Specifically, it is preferable to keep the set value c and the set value e as the heat cut-off time constant, and set the set value d to be shorter than the set value b for the heat supply time, or conversely, set the set value d as the heat supply time. The set value b and the set value d of the time are made constant, and the set value e is set to be longer than the set value c for the thermal shutdown time.

Next, it is judged whether it is heat supply (S60). When it is determined that the heat supply is in progress, it is determined whether or not the heat supply time has elapsed (S70). If the heat supply time has not elapsed, the heat cutoff control is directly terminated (S110).

On the other hand, when the heat supply time has elapsed, the expansion valve 14 is closed by the control device 22, the cooling device 10 is thermally shut off (S80), and the thermal shutoff control is terminated (S110).

In S60, when it is determined that the thermal shutdown is in progress, it is judged whether or not the thermal shutdown time has elapsed (S90). If the thermal cutoff time has not elapsed, the thermal cutoff control is directly terminated (S110).

On the other hand, when the heat cutoff time has elapsed, the expansion valve 14 is opened by the control device 22 to supply heat to the cooling device 10 (S100), and the heat cutoff control is terminated (S110).

In this way, in the constant temperature control in the refrigerator, the heat supply state and the heat cut-off state are switched with the predetermined heat supply time and the heat cut-off time, so that the defrosting effect can be obtained during the heat cut-off, so the growth of frost in the evaporator 16 is prevented. , which can extend the defrost cycle time.

In addition, during the heat supply, the internal temperature of the counter is kept constant by the internal temperature constant control, and even if the heat cut-off state is set for a short time, the internal temperature does not rise so much, so the operation of the control device 22 of this embodiment The temperature inside the warehouse is maintained stably.

In addition, in this embodiment, the heat supply time and the heat cut-off time are changed in the first half and the second half of the defrosting cycle for the above-mentioned reason, but the heat supply time and the heat cut-off time may always be the same.

In addition, instead of setting only one switching judgment time and switching between the first half and the second half of the defrosting cycle, it is also possible to set multiple switching judgment times, divide the defrosting cycle into finer points, and set different Heat supply time and heat cut-off time.

As mentioned above, the preferred embodiment of the present invention has been described, but the present invention is not limited thereto. In the above-mentioned embodiment, a multi-level counter installed in a store or the like is used as an example of the cooling room for description. However, for example, it is also possible to apply Various changes can be made in flat counters, prefabricated coolers, prefabricated freezers, etc. within the scope not departing from the purpose of the present invention.

Claims (6)

1. the control device of a cold room, for controlling the control device of the valve opening of above-mentioned expansion valve in the cold room at least with pipe arrangement, expansion valve and evaporimeter, wherein, flow of refrigerant is had in above-mentioned pipe arrangement, above-mentioned expansion valve is arranged on above-mentioned pipe arrangement, and the condensed liquid refrigerant of device that makes to be condensed becomes the liquid refrigerant of low-temp low-pressure, above-mentioned evaporimeter carrys out the heat of the air of absorption cycle by making the state of cold-producing medium be changed to gas from liquid and cools, the feature of the control device of this cold room is

The thermal cut-out time of above-mentioned control device to the regulation that the heat supply time of the regulation that cold-producing medium flows in above-mentioned evaporimeter and cold-producing medium do not flow in above-mentioned evaporimeter stores,

Alternately repeatedly carry out in storehouse temperature constant control being become the heat supply operation of heat supply state the above-mentioned expansion valve valve opening above-mentioned heat supply time and being become the thermal cut-out operation of thermal cut-out state above-mentioned for the above-mentioned expansion valve valve closing thermal cut-out time.

2. the control device of cold room according to claim 1, is characterized in that,

Be configured to, the switching determination time that above-mentioned control device storage presets,

From cooling through the above-mentioned switching determination time when, be judged to be that the upper frost amount of above-mentioned evaporimeter exceedes the threshold value of regulation, will the value that above-mentioned heat supply time of above-mentioned control device and above-mentioned thermal cut-out time change are regulation be stored in.

3. the control device of cold room according to claim 2, is characterized in that,

Compared with before the above-mentioned switching determination time, large relative to the ratio of heat supply time for break time through above-mentioned switching determination time after heat.

4. the control method of a cooling device, for controlling the control method of the valve opening of above-mentioned expansion valve in the cold room at least with pipe arrangement, expansion valve and evaporimeter, wherein, flow of refrigerant is had in above-mentioned pipe arrangement, above-mentioned expansion valve is arranged on above-mentioned pipe arrangement, and the condensed liquid refrigerant of device that makes to be condensed becomes the liquid refrigerant of low-temp low-pressure, above-mentioned evaporimeter carrys out the heat of the air of absorption cycle by making the state of cold-producing medium be changed to gas from liquid and cools, the feature of the control method of this cold room is

Heat supply time of above-mentioned expansion valve valve opening being specified alternately repeatedly is carried out and the heat supply operation becoming heat supply state and thermal cut-out time of above-mentioned expansion valve valve closing being specified and become the thermal cut-out operation of thermal cut-out state in storehouse temperature constant control.

5. the control method of cooling device according to claim 4, is characterized in that,

From cooling through the switching determination time preset when, be judged to be that the upper frost amount of above-mentioned evaporimeter exceedes the threshold value of regulation, will the value that above-mentioned heat supply time of control device and above-mentioned thermal cut-out time change are regulation be stored in.

6. the control method of cooling device according to claim 5, is characterized in that,

Compared with before the above-mentioned switching determination time, large relative to the ratio of heat supply time for break time through above-mentioned switching determination time after heat.