JP2016080306A - Control device and control method of cooling box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device and a control method of a cooling box, capable of quickly recovering a state from a cooling failure state by automatically switching a control method, in a case where a cooling box is in the cooling failure state.SOLUTION: When cooling failure of a cooling box is detected, a control device of the cooling box switches a cooling control method to another cooling control method to perform in-box cooling.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a refrigerator control device capable of detecting when a cooling failure occurs in a refrigerator such as a refrigerated showcase or a refrigerated showcase installed in a store or the like and quickly recovering the state. It relates to a control method.

  For example, in stores such as supermarkets and convenience stores, showcases such as frozen showcases and refrigerated showcases for displaying products in a frozen or refrigerated state are used.

  As shown in FIG. 1, such a showcase 30 circulates in the showcase 30 by displaying a display shelf 32 for displaying commodities, a blow-out port 34 for blowing cool air to the display shelf, and sucking in air from the display shelf. And a suction port 36 having a fan 38 to be operated.

  In the showcase 30, a general refrigeration cycle is used, and the expansion of the pipe 12 through which the refrigerant flows and the liquid refrigerant provided on the pipe 12 and condensed by the condenser into low-temperature and low-pressure liquid refrigerant. A valve 14 and an evaporator 16 that absorbs and cools the heat of the circulating air by changing the state of the refrigerant from liquid to gas.

  When such a showcase is installed in a store, although not shown, the compressor compresses the gas refrigerant discharged from the evaporator into a high-temperature / high-pressure gas refrigerant, and is discharged from the compressor. A refrigerator equipped with a condenser that releases heat from a high-temperature and high-pressure gas refrigerant to form a liquid refrigerant is installed outdoors, and multiple showcases are connected to a single refrigerator. There are many. However, there may be a case where only one showcase is connected to one refrigerator.

  A showcase in which a refrigerator is separately installed outdoors is called a separate showcase. On the other hand, there is a showcase in which refrigerator parts such as a compressor and a condenser are integrated, and such a showcase is called a refrigerator built-in type showcase or a built-in type showcase.

  The cooler such as the showcase 30 has a control device 22, and the control device 22 provides illumination 26, a fan 38, a defrost heater 24, a dew-proof heater, and an expansion valve 14 (temperature control valve) included in the showcase. Etc. are controlled.

  When a mechanical expansion valve that automatically adjusts the degree of superheat with the temperature sensing cylinder and the pressure inside the pipe is used as the expansion valve 14 of the showcase 30, the liquid is supplied before the expansion valve 14 (on the refrigerator side). An electromagnetic valve is provided, and the controller 22 switches between thermo-on and thermo-off, and adjusts the internal temperature.

  Further, the control device 22 is provided with valve opening control output means for controlling the valve opening of the expansion valve 14, and a high durability electromagnetic valve or an electronic expansion valve is used as the expansion valve 14. Some are configured to control the valve opening.

  Even when a highly durable electromagnetic valve or an electronic expansion valve is used as the expansion valve 14, a liquid supply electromagnetic valve is provided in front of the expansion valve 14 (on the refrigerator side), and the liquid supply electromagnetic valve is controlled by the control device 22. The control device 22 adjusts the valve opening of the expansion valve 14 while the thermo-ON is on by controlling the degree of superheat or controlling the internal temperature at a constant temperature while switching the thermo-ON and thermo-OFF with However, when a highly durable solenoid valve or an electronic expansion valve having a valve closing function is used as the expansion valve 14, the expansion valve 14 performs the role of the supply solenoid valve, and the supply solenoid valve Is often omitted.

  The control device 22 serves as superheat degree detection means for detecting the superheat degree in the evaporator 16, an inlet pipe temperature sensor 18 for detecting the temperature of the refrigerant on the inlet side of the evaporator, and the temperature of the refrigerant on the outlet side of the evaporator. And an outlet pipe temperature sensor 20 for detecting the temperature of the outlet, and a temperature sensor 40 for detecting the temperature of the outlet 34 and a temperature of the inlet 36 as the temperature detecting means for detecting the inside temperature. A suction port temperature sensor.

  Note that the control device 22 uses both the outlet temperature detected by the outlet temperature sensor 40 and the inlet temperature detected by the inlet temperature sensor 42, and treats an intermediate temperature as the internal temperature. Alternatively, only one of the temperature sensors may be used, and a value obtained by adding an offset to the temperature detected by the temperature sensor may be handled as the internal temperature.

  Furthermore, using only one of the temperature sensors, the temperature detected by the outlet temperature sensor can be used as the inside temperature, or the temperature detected by the suction port temperature sensor can be used as the inside temperature. When the inside temperature is obtained using only one of these temperature sensors, it is not necessary to provide both the outlet temperature sensor and the inlet temperature sensor, only the temperature sensor on the side to be used is provided. Just do it.

  The showcase 30 configured as described above is disclosed in ON / OFF control for switching and controlling a thermo-on state in which the refrigerant flows through the evaporator 16 and a thermo-off state in which the refrigerant is not flown, and Patent Documents 1 and 2 and the like. Thus, the method of controlling the cooling capacity by adjusting the opening degree of the expansion valve 14 by the control device 22 and changing the flow rate of the refrigerant is used, and the inside temperature of the showcase 30 is adjusted.

  As a cooling control method for adjusting the valve opening degree 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 inside temperature (constant inside temperature control) are known. ing.

  Note that the superheat degree control and the constant internal temperature control are performed by PID control by a microcomputer mounted on the control device 22. Such PID control includes position type PID control and speed type PID control. In this specification, the embodiment adopts speed type PID control.

In the superheat degree control, the valve opening degree of the expansion valve 14 is adjusted so that the superheat degree becomes a predetermined superheat degree set value.
When superheat control is performed with speed-type PID control, the proportional component of the control output is an output that decreases the valve opening when the superheat is decreasing (the change in the superheat is negative). When the degree of superheat increases (the amount of change in the degree of superheat is positive), the output increases the valve opening.

  As the degree of superheat, a value obtained by subtracting the refrigerant temperature (evaporation temperature) on the inlet side of the evaporator 16 from the refrigerant temperature (return pipe temperature) on the outlet side of the evaporator 16 is used. The controller 22 is configured to calculate the detected evaporation temperature and the return pipe temperature detected by the outlet pipe temperature sensor 20.

  In the case where 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 so that the low pressure can be detected, the low pressure is set to the saturation temperature. The value obtained by subtracting the evaporation temperature from the return pipe temperature detected by the outlet pipe temperature sensor 20 can also be used as the degree of superheat, with the converted value as the evaporation temperature.

Further, in the constant chamber temperature control, the opening degree of the expansion valve 14 is adjusted so that the chamber temperature approaches a predetermined chamber temperature set value.
When the internal temperature constant control is also performed by speed-type PID control, as in the superheat control, the proportional component of the control output is when the internal temperature decreases (the amount of change in the internal temperature is negative). ), The valve opening is reduced, and when the internal temperature is increasing (the amount of change in the internal temperature is positive), the valve opening is increased.

  The control method used in the control device employs PID control using an electronic expansion valve or a high durability electromagnetic valve as in the cited document 1, but is not an electronic expansion valve or a high durability electromagnetic valve, but a mechanical type. In the control device attached to the cooler using the expansion valve, the internal temperature is adjusted by turning on / off the liquid supply electromagnetic valve attached on the upstream side of the mechanical expansion valve.

JP 59-185948 A JP 2008-209016 A

In such a showcase 30, when the refrigerator is stopped, the refrigerant is not sucked by the refrigerator, so the evaporation temperature becomes high, and the evaporation temperature and the return pipe temperature become the same temperature. Then, the control device 22 recognizes that the degree of superheat has become almost zero.
In the superheat degree control, when the superheat degree is approximately 0, the valve opening degree may be reduced to a lower limit of a preset control output.

  In this state, when the refrigerator is restored, the amount of refrigerant flowing into the evaporator 16 is extremely reduced, and the refrigerant completely evaporates before the position where the inlet pipe temperature sensor 18 is attached, so that the refrigerant enters the evaporator 16. There will be almost no state.

  For this reason, even if the refrigerator is restored, the control device 22 continues the state in which the evaporation temperature and the return pipe temperature are substantially the same, that is, the superheat degree is recognized as substantially 0, and the valve of the expansion valve 14 Leave the opening at the lower limit of the preset control output and do not increase the valve opening. For this reason, the evaporator 16 falls into a so-called “no-liquid state” in which no refrigerant exists, and the superheat degree cannot be normally controlled, resulting in poor cooling.

  Also, during constant chamber temperature control, if the chamber temperature is higher than the chamber temperature set value, the valve opening is increased, but by increasing the valve opening, a sufficient degree of superheat can no longer be obtained. In this case, the refrigerant does not completely evaporate in the evaporator 16, and the so-called “liquid back state” is obtained.

  Even if the opening degree of the expansion valve 14 is increased in this state, the liquid back amount only increases, the degree of superheat does not increase, and the capacity of the evaporator 16 cannot be increased, resulting in poor cooling. Sometimes.

  When a cooling failure occurs in this way, it takes time to return to a normal state even if the operation of the control device 22 is continued. Further, if it is not likely to return to a normal state, the control device 22 may have to be reset.

  In the present invention, in view of such a current situation, when the refrigerator falls into a cooling failure, by automatically switching the control method, a cooling device control device that can quickly recover from the cooling failure state, and An object is to provide a control method.

The control device and control method for a refrigerator of the present invention uses a highly durable electromagnetic valve or an electronic expansion valve as an expansion valve, and controls the valve opening degree by the control device.
Specifically, the control device for the refrigerator of the present invention is:
Piping through which refrigerant flows;
An expansion valve that is provided on the pipe and condensed by a condenser with a low-temperature and low-pressure liquid refrigerant;
An evaporator that absorbs and cools the heat of the circulating air by changing the state of the refrigerant from liquid to gas;
In a refrigerator having at least, a control device for controlling the valve opening of the expansion valve by a plurality of cooling control methods,
When the control device detects a cooling failure of the refrigerator, the controller is configured to switch the cooling control method to another cooling control method and perform internal cooling.

The plurality of cooling control methods preferably include superheat degree control and constant internal temperature control.
In this case, the control device can be configured to determine that a cooling failure has occurred when a predetermined superheat control upper limit time has elapsed from the start of the superheat control during the superheat control.

  In addition, during the constant temperature control, the control device causes a cooling failure when the predetermined internal temperature constant control upper limit time has elapsed with the internal temperature exceeding the predetermined internal temperature upper limit value. It can also be configured to determine that it has occurred.

Moreover, the control method of the refrigerator of the present invention is:
Piping through which refrigerant flows;
An expansion valve that is provided on the pipe and condensed by a condenser with a low-temperature and low-pressure liquid refrigerant;
An evaporator that absorbs and cools the heat of the circulating air by changing the state of the refrigerant from liquid to gas;
In a refrigerator having at least, a control method for controlling the opening degree of the expansion valve by a plurality of cooling control methods,
When a cooling failure of the cooling box is detected, the cooling control method is switched to another cooling control method to cool the inside of the box.

The plurality of cooling control methods preferably include superheat degree control and constant internal temperature control.
In this case, during the superheat control, it can be determined that a cooling failure has occurred when a predetermined superheat control upper limit time has elapsed since the start of the superheat control.

  In addition, it is determined that a cooling failure has occurred when the predetermined internal temperature constant control upper limit time has elapsed while the internal temperature exceeds the predetermined internal temperature upper limit value during the constant internal temperature control. You may do it.

  According to the present invention, for example, when cooling is performed by superheat degree control, when the refrigerator falls into a cooling failure, the control method is switched from superheat degree control to constant internal temperature control. Therefore, it is possible to quickly return to the normal cooling state and keep the interior temperature stable without operating the refrigerator in a state of poor cooling and increasing the interior temperature.

FIG. 1 is a schematic configuration diagram for explaining the structure of a showcase provided with the control device of this embodiment. 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 fail-safe control in the control device of the present embodiment.

Hereinafter, embodiments (examples) of the present invention will be described in more detail with reference to the drawings.
In addition, the structure of the showcase 30 provided with the control apparatus 22 in a present Example is a structure similar to the conventional showcase 30 mentioned above fundamentally.

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 PID control arithmetic processing, a power input terminal 52 for receiving operating power, and a temperature for inputting a temperature signal from each of the temperature sensors 18, 20, 40, 42. A sensor input terminal 54 and a control output terminal 56 for outputting a control signal to the expansion valve 14, the fan 38, the defrost heater 24, and the illumination 26 are provided.

  In addition, for example, the communication terminal 58 for communicating with a host control device (not shown) that controls a plurality of showcases 30 and refrigerators in an integrated manner, and the temperature sensors 18, 20, 40, 42. A display means 60 for displaying the detected temperature and the state of the expansion valve 14 can also be provided.

  The inside cooling of the showcase 30 has two stages, one is pull-down cooling from room temperature to a predetermined temperature, and the other is constant temperature that maintains the inside temperature at a predetermined temperature. Cooling.

  In the control device 22 of the present embodiment, normally, cooling is performed by superheat degree control during pull-down cooling, and cooling is performed by constant temperature control during constant temperature cooling. Thus, the control device 22 of the present invention is configured to perform cooling by a plurality of control methods.

  And, for example, when the refrigerator stops or falls into the “no liquid state” and becomes a cooling failure, switch from superheat degree control to constant temperature control inside the compartment, or inside temperature It is configured to switch from constant control to superheat degree control.

  That is, when a cooling failure occurs during the cooling operation and the control device 22 detects a cooling failure, the control device 22 is configured to perform cooling by a different control method. As described above, the control device 22 according to the present embodiment has the fail-safe control, so that even when a cooling failure occurs, the control device 22 can quickly recover from the cooling failure state by switching the control method.

Hereinafter, fail-safe control in the control device 22 of the present embodiment will be described based on the flowchart shown in FIG.
In this embodiment, when the control device 22 is activated, fail-safe control is executed at predetermined intervals (S10).

  First, it is determined whether the control device 22 is under superheat degree control or constant temperature control (S20). If it is determined that the superheat control is being performed, it is determined whether a predetermined superheat control upper limit time has elapsed since the start of the superheat control (S30).

  If the superheat degree control upper limit time has not elapsed, the fail safe control is terminated as it is (S70). On the other hand, if the superheat degree control upper limit time has elapsed, it is determined that a cooling failure has occurred, the control method is switched from superheat degree control to constant internal temperature control (S40), and failsafe control ends. (S70).

  In S20, when it is determined that the control device 22 is under constant control of the internal temperature, the internal temperature of the showcase 30 is the internal temperature set value + the internal temperature upper limit value that is a predetermined offset value. In a state where it has exceeded, it is determined whether or not a predetermined constant internal temperature control upper limit time has elapsed (S50).

  If the internal temperature constant control upper limit time has not elapsed, the fail safe control is terminated as it is (S70). On the other hand, when the upper limit temperature constant control upper limit time has passed, it is determined that a cooling failure has occurred, and the control method is switched from the constant chamber temperature control to the superheat control (S60). The process ends (S70).

Note that the superheat degree control upper limit time, the internal temperature constant control upper limit time, and the offset value of the internal temperature set value can be appropriately set according to the type and size of the showcase 30.
Moreover, in the said Example, although the control apparatus 22 cools the inside of the showcase 30 by the combination of superheat degree control and internal temperature constant control, it is not restricted to this, For example, the refrigerant | coolant using a pressure sensor Other control methods may be used such as control based on the pressure.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to this, In the said Example, although demonstrated using the multistage showcase installed in a store etc. as an example of a refrigerator. For example, various modifications are possible without departing from the object of the present invention, such as being applicable to a flat showcase, a prefabricated refrigerator, a prefabricated freezer, and the like.

DESCRIPTION OF SYMBOLS 12 Piping 14 Expansion valve 16 Evaporator 18 Inlet piping temperature sensor 20 Outlet piping temperature sensor 22 Control device 24 Defrost heater 30 Showcase 32 Display shelf 34 Outlet 36 Inlet port 38 Inlet fan 40 Outlet temperature sensor 42 Inlet temperature sensor 50 microcomputer 52 power input terminal 54 temperature sensor input terminal 56 control output terminal 58 communication terminal 60 display means

Claims (8)

Piping through which refrigerant flows;
An expansion valve provided on the pipe, the liquid refrigerant condensed by the condenser is a low-temperature, low-pressure liquid refrigerant;
An evaporator that absorbs and cools the heat of the circulating air by changing the state of the refrigerant from liquid to gas;
In a refrigerator having at least, a control device for controlling the valve opening of the expansion valve by a plurality of cooling control methods,
Control of the refrigerator, wherein when the controller detects a cooling failure of the refrigerator, the cooling control method is switched to another cooling control method to perform internal cooling. apparatus.   The cooling device control device according to claim 1, wherein the plurality of cooling control methods include superheat degree control and constant temperature control.   The control device is configured to determine that a cooling failure has occurred when a predetermined superheat control upper limit time has elapsed from the start of superheat control during superheat control. 2. The refrigerator control device according to 2.   The control device has a cooling failure when a predetermined internal temperature constant control upper limit time has elapsed in the state where the internal temperature exceeds a predetermined internal temperature upper limit value during the internal temperature constant control. It is comprised so that it may be judged. The control apparatus of the refrigerator of Claim 2 or 3 characterized by the above-mentioned. Piping through which refrigerant flows;
An expansion valve that is provided on the pipe and condensed by a condenser with a low-temperature and low-pressure liquid refrigerant;
An evaporator that absorbs and cools the heat of the circulating air by changing the state of the refrigerant from liquid to gas;
In a refrigerator having at least, a control method for controlling the opening degree of the expansion valve by a plurality of cooling control methods,
A cooling chamber control method characterized in that when a cooling failure of the cooling cabinet is detected, the cooling control method is switched to another cooling control method to cool the inside of the cabinet.   6. The cooling chamber control method according to claim 5, wherein the plurality of cooling control methods include superheat degree control and constant chamber temperature control.   The method of controlling a refrigerator according to claim 6, wherein during the superheat control, when a predetermined superheat control upper limit time has elapsed from the start of the superheat control, it is determined that a cooling failure has occurred.   It is determined that a cooling failure has occurred when a predetermined internal temperature constant control upper limit time has elapsed in a state where the internal temperature has exceeded a predetermined internal temperature upper limit during the internal temperature constant control. The method for controlling a refrigerator according to claim 6 or 7, characterized in that:

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