JP2006284074A - Control device of cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a cooling device capable of performing a quick response by independently determining an abnormality of an electric expansion valve, and preventing the generation of a fatal state such as defective cooling by a cooler. <P>SOLUTION: This cooling device 1 comprises a control device 30 controlling the electric expansion valve 4, temperature sensors 10, 11 as means for detecting a superheating degree of a refrigerant in the cooler 6, and an evaporation temperature sensor 12 detecting an evaporation temperature of the cooler 6. The control device 30 controls a valve opening of the electric expansion valve 4 on the basis of the detected superheating degree of a refrigerant, determines the abnormality of the electric expansion valve 4 on the basis of the valve opening of the electric expansion valve 4 obtained by the control device 30, the evaporation temperature of the refrigerant detected by the evaporation temperature sensor 12 and/or the detected superheating degree, and continues the operation and holds information on the abnormality when the abnormality is within a prescribed operational range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device installed in a low-temperature showcase, a low-temperature storage, or the like, and more particularly to a control device that controls an electric expansion valve.

  Conventionally, for example, a cooling device employed in a low-temperature showcase forms a predetermined refrigerant circuit by sequentially connecting a compressor, a condenser, a decompression device, a cooler, and the like in a circular manner by piping, and in the refrigerant circuit, A predetermined amount of refrigerant is enclosed. When the compressor is operated, the refrigerant is compressed into a high-temperature and high-pressure gas state and flows into the condenser. In the condenser, the refrigerant dissipates heat and is condensed and liquefied, and then decompressed by the decompression device and supplied to the cooler. In the cooler, the liquid refrigerant after being depressurized evaporates, and at that time, it absorbs heat from the surroundings and exhibits a cooling action.

  Here, in order to precisely control the cooling action by the cooler, an electric expansion valve is used as a decompression device (see Patent Document 1). Normally, this electric expansion valve controls the flow rate of the refrigerant circulating in the refrigerant circuit to depressurize the condensed refrigerant, and the valve opening degree is adjusted according to the cooling load.

Such an electric expansion valve rotates a stepping motor built in the electric expansion valve by an arbitrary angle according to the number of pulses of the drive voltage output from the control device, and this rotation amount is advanced or retracted with respect to the valve seat of the valve element. The valve opening degree is adjusted by converting the movement amount.
Japanese Patent No. 2538444

  Conventional control devices for cooling devices generally detect abnormality of the electric expansion valve, the compressor, or the control device itself based on the refrigerant inlet temperature and refrigerant outlet temperature of the cooler or the discharge temperature and suction temperature of the compressor. It was. Therefore, when an abnormality occurs in the electric expansion valve, it is impossible to directly detect the abnormality of the electric expansion valve. In particular, an electric expansion valve that adjusts the opening degree by a stepping motor is difficult to directly grasp the operating state of the valve drive unit, and is difficult to detect when an abnormality occurs in the electric expansion valve body. Met. Therefore, it is a serious problem to quickly cope with the abnormality of the electric expansion valve that plays a major role in the cooling device.

  Further, in the conventional control device for the cooling device, when an abnormality is detected in the electric expansion valve, the compressor, or the control device itself, the operation of the cooling device is stopped, so that the space to be cooled by the cooling device is continued. As a result, the cooling cannot be performed, resulting in inconvenience.

  Therefore, the present invention has been made to solve the conventional technical problem, and it is possible to take a quick action by determining the abnormality of the electric expansion valve alone, and the cooling failure of the cooler. A control device for a cooling device that can avoid a fatal state such as the above is provided.

  The control device for the cooling device of the present invention is a cooling device in which a compressor, a condenser, an electric expansion valve, and a cooler are sequentially connected in a pipe, and includes a control means for controlling the electric expansion valve, and a refrigerant in the cooler. A superheat degree detecting means for detecting the superheat degree, and an evaporating temperature detecting means for detecting the evaporating temperature of the refrigerant in the cooler, and the control means is based on the superheat degree of the refrigerant in the cooler detected by the superheat degree detecting means, While controlling the valve opening degree of the electric expansion valve, the valve opening degree of the electric expansion valve grasped by the control means, and the evaporation temperature and / or superheat degree detection means of the refrigerant in the cooler detected by the evaporation temperature detection means The abnormality of the electric expansion valve is determined based on the superheat degree of the refrigerant in the cooler detected by the engine, and when the abnormality is within a predetermined operable range, the operation is continued and the abnormality information is retained. That And butterflies.

  The invention according to claim 2 is that, in the above, the control means determines whether the evaporating temperature and / or superheat degree assumed from the valve opening degree of the electric expansion valve currently grasped is the refrigerant in the cooler detected by the evaporating temperature detecting means. When the evaporating temperature and / or the superheat degree detection means is away from the superheat degree of the refrigerant in the cooler by a predetermined value or more, it is determined that the electric expansion valve is abnormal.

  The invention of claim 3 is characterized in that, in each of the above-mentioned inventions, the control means includes a predetermined display means, and displays information of abnormality on the display means.

  The invention of claim 4 is characterized in that, in each of the above inventions, the control means outputs abnormality information to the outside.

  According to the present invention, in a cooling device in which a compressor, a condenser, an electric expansion valve, and a cooler are sequentially connected in a circular pipe, the control means for controlling the electric expansion valve and the degree of superheat of the refrigerant in the cooler are detected. And an evaporating temperature detecting means for detecting the evaporating temperature of the refrigerant in the cooler, and the control means is based on the superheated degree of the refrigerant in the cooler detected by the superheat detecting means. While controlling the valve opening, the valve opening of the electric expansion valve grasped by the control means, the refrigerant evaporating temperature in the cooler detected by the evaporating temperature detecting means, and / or the cooling detected by the superheat degree detecting means By determining the abnormality of the electric expansion valve based on the superheat degree of the refrigerant in the cooler, it is possible to easily grasp the abnormality of the electric expansion valve before it becomes a fatal state such as a cooling failure of the cooler It becomes.

  In particular, as in the second aspect of the invention, the control means is a refrigerant in the cooler in which the evaporating temperature and / or superheat degree estimated from the valve opening degree of the electric expansion valve currently grasped is detected by the evaporating temperature detecting means. The abnormality of the electric expansion valve is more reliably determined by determining the abnormality of the electric expansion valve when the evaporating temperature of the refrigerant and / or the superheat degree of the refrigerant detected by the superheat degree detection means is more than a predetermined value away from the refrigerant superheat degree Can be grasped.

  Further, the present invention, when the abnormality of the electric expansion valve as described above is within a predetermined operable range, continues the operation of the cooling device and retains information on the abnormality, thereby If it is within the operable range while grasping the abnormality, the cooling device can be operated according to the degree of abnormality of the electric expansion valve by continuously operating.

  Therefore, when a minor abnormality that is within a range where the electric expansion valve can be operated occurs, it is possible to cope without stopping the operation. In addition, since the control means holds the information on the abnormality, it is possible for the operator to grasp the information on the abnormality at the next maintenance, and it is possible to quickly cope with the abnormality of the electric expansion valve. It becomes.

According to the invention of claim 3, in each of the above inventions, the control means is provided with a predetermined display means, and the abnormality information is displayed on the display means, whereby the abnormality information can be easily grasped. Thus, it becomes possible to quickly cope with the abnormality of the electric expansion valve.
It is characterized by.

  According to the invention of claim 4, in each of the above inventions, the control means can promptly notify the operator of the abnormality of the electric expansion valve by outputting abnormality information to the outside. As a result, it becomes possible to cope with the abnormality of the electric expansion valve even more quickly, and it is possible to avoid a fatal state such as a cooling failure of the cooler.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a refrigerant circuit diagram of a cooling device 1 according to an embodiment to which the present invention is applied, FIG. 2 is a schematic sectional view of an electric expansion valve 4 in the cooling device 1 of FIG. 1, and FIG. FIG. 4 shows a circuit diagram of the electric expansion valve 4.

  The cooling device 1 of the present embodiment is employed in, for example, a low temperature showcase, and the compressor 2, the condenser 3, the electric expansion valve 4, the liquid pipe electromagnetic valve 5, and the cooler 6 are piped. A refrigerant circuit is formed by sequentially connecting to the ring 7 and a predetermined amount of refrigerant is sealed in the circuit. A condenser blower 8 is installed in the vicinity of the condenser 3, and a cooler blower 9 is installed in the vicinity of the cooler 6.

  Further, a refrigerant inlet side temperature sensor 10 and a refrigerant outlet side temperature sensor 11 for detecting the respective refrigerant temperatures are provided on the refrigerant inlet side and the refrigerant outlet side of the cooler 6 (note that these refrigerant inlet side temperature sensor 10 and refrigerant outlet side). The side temperature sensor 11 constitutes superheat degree detection means.) And an evaporation temperature sensor 12 for detecting the evaporation temperature of the refrigerant in the cooler 6 is provided.

  The electric expansion valve 4 controls the flow rate of the refrigerant flowing in the refrigerant circuit constituting the cooling device 1 to depressurize the condensed refrigerant, and the valve opening degree is adjusted according to the cooling load. Here, the configuration of the electric expansion valve 4 will be described with reference to FIG. In the electric expansion valve 4, the valve body 16 is linearly moved in the axial direction by the driving force (that is, driving torque) of the stepping motor 15 constituting the valve driving unit, and the valve opening degree is adjusted. It is controlled by a control device 30 constituted by a general-purpose microcomputer as shown.

  As shown in FIG. 2, the electric expansion valve 4 includes a main body 17, a valve body 16, a valve seat 18 and a stepping motor 15. A flow path 21 communicating with the inlet joint 19 and the outlet joint 20 is formed in the main body 17, and a valve seat 18 protrudes at a position facing the tip of the valve body 16 in the flow path 21. The base end portion of the valve body 16 is positioned to face the valve seat 18, and the male screw portion 22 is fixed to the distal end portion of the valve body 16. At least one of the male screw portion 22 and the valve body 16 is configured to be movable in the axial direction with respect to the main body 17 and not rotatable about the axis. Further, the stepping motor 15 includes a stator 26 having a coil 25 and a rotor 27. On the inner periphery of the rotor 27, a female screw portion 23 that is screwed into the male screw portion 22 is fixed.

  When a drive voltage pulse is output from the control device 30 to the coil 25 of the stator 26 in the stepping motor 15 as will be described later, the rotor 27 is rotated by an arbitrary angle and driven according to the number of pulses. The amount of rotation is converted into the amount of forward / backward movement of the valve body 16 by the action of the female screw portion 23 and the male screw portion 22. Thereby, the front-end | tip part of the valve body 16 moves forward / backward with respect to the valve seat 18, and the valve opening degree of the electric expansion valve 4 is adjusted.

  As shown in FIG. 4, the electric expansion valve 4 is connected to the control device 30 via a pulse generation circuit 32 and a drive circuit 33. The control device 30 controls the rotation direction and speed of the stepping motor 15. The pulse generation circuit 32 generates a drive voltage pulse based on a signal from the control device 30, and distributes and outputs the pulse to, for example, four coils 25 in the stator 26 in order. The drive circuit 33 amplifies the drive voltage pulse, for example, amplifies it from 5 V to 12 V, and outputs it to each coil 25.

  Further, as shown in FIG. 3, the control device 30 includes, on the input side, a refrigerant inlet side temperature sensor 10 that detects a refrigerant inlet side temperature of the cooler 6 and a refrigerant that detects a refrigerant outlet side temperature of the cooler 6. An outlet side temperature sensor 11 and an evaporation temperature sensor 12 for detecting the evaporation temperature of the refrigerant in the cooler 6 are connected. In addition to the electric expansion valve 4, a liquid pipe solenoid valve 5, a display unit 35, a central management unit provided outside, a buzzer or an alarm lamp (not shown), and the like are connected to the output side. The display unit 35 displays information on abnormality of the electric expansion valve 4. In addition, a control panel (not shown) is connected to the input side of the control device 30, and a compressor 2, a condenser blower 8, a cooler blower 9 and the like are not shown in FIG. It shall be connected.

  With the above configuration, when the operation of the cooling apparatus 1 is started by operating the control panel, the control apparatus 30 outputs the outputs of the refrigerant inlet side temperature sensor 10 and the refrigerant outlet side temperature sensor 11 or the cooling apparatus. The compressor 2, the condenser blower 8, and the cooler blower 9 are controlled to operate based on the output of a temperature sensor (not shown) provided in the space to be cooled that is cooled by 1. The control device 30 always opens the liquid pipe solenoid valve 5.

  And the control apparatus 30 calculates the superheat degree in the said cooler 6 based on the output of the temperature sensors 10 and 11 provided in the inlet side and outlet side of the refrigerant | coolant of the cooler 6, and an electric expansion valve based on the said superheat degree 4 is controlled.

  That is, when the degree of superheat is higher than a predetermined value, for example, 10 deg, the control device 30 issues a signal for increasing the opening degree of the electric expansion valve 4 to the pulse generation circuit 32. Based on the signal, the pulse generation circuit 32 generates a pulse of a predetermined drive voltage, the drive circuit 33 amplifies the pulse of the drive voltage, and outputs it to each coil 25 of the electric expansion valve 4. Thereby, the stepping motor 15 rotates forward according to the number of the pulse signals, and increases the refrigerant flow rate of the electric expansion valve 4.

  On the other hand, when the degree of superheat is lower than a predetermined value, for example, 10 deg, the control device 30 issues a signal for lowering the opening degree of the electric expansion valve 4 to the pulse generation circuit 32. Based on the signal, the pulse generation circuit 32 generates a pulse of a predetermined drive voltage, the drive circuit 33 amplifies the pulse of the drive voltage, and outputs it to each coil 25 of the electric expansion valve 4. Thereby, the stepping motor 15 rotates reversely according to the number of pulse signals, and decreases the refrigerant flow rate of the electric expansion valve 4.

  Thus, the flow rate of the refrigerant supplied to the cooler 6 is controlled at any time by the electric expansion valve 4, and the refrigerant is evaporated in the cooler 6 with an appropriate degree of superheat. Therefore, the liquid back to the compressor 2 that occurs when the degree of superheat falls below a predetermined value can be avoided in advance.

  Here, when performing the opening degree control of the electric expansion valve 4, the control device 30 always grasps the current opening degree of the electric expansion valve 4 and stores it in a ROM (not shown) provided in the control device 30. . Further, the degree of superheat in the cooler 6 that is assumed in advance based on the opening degree of the electric expansion valve 4 is stored in the ROM. In addition, since the superheat degree assumed by the opening degree of the electric expansion valve 4 differs depending on each device such as the compressor 2 constituting the cooling device 1 and a combination thereof, the control device 30 is in a normal state. It is assumed that the degree of superheat in the cooler 6 assumed in advance according to the opening of the electric expansion valve 4 is stored in the ROM.

  The controller 30 outputs the degree of superheat in the cooler 6 calculated based on the outputs of the temperature sensors 10 and 11 provided on the refrigerant inlet side and outlet side of the cooler 6 as needed. Further, the difference between the present superheat degree and the superheat degree in the cooler 6 assumed in advance by the opening degree of the electric expansion valve 4 stored in the ROM as described above is calculated. If the difference between the assumed degree of superheat and the current degree of superheat is equal to or greater than a predetermined abnormality occurrence value, for example, 5 deg or greater, the electric expansion valve 4 is abnormal, for example, the coil 25 is disconnected or the communication lines are connected to each other. It is determined that a short circuit has occurred.

  Thereby, for example, even when an overshoot in which the refrigerant in the cooler 6 completely evaporates and the superheat degree becomes remarkably large is generated, the superheat degree assumed for the opening degree of the electric expansion valve 4 The abnormality of the electric expansion valve 4 can be determined by comparing the degree of superheat. Further, when the electric expansion valve 4 is controlled to be fully closed, for example, when performing a defrosting operation, when the electric expansion valve 4 is abnormal and the refrigerant is circulating, Abnormality can be determined by the degree of superheat.

  In addition, when the difference in the degree of superheat is not less than the predetermined abnormality occurrence value, that is, 5 deg and within a continuously operable range, for example, 6 deg or less, the control device 30 displays on the display unit 35. While displaying the information of abnormality of the electric expansion valve 4, the cooling device 1 is continuously operated.

  For this reason, even if an abnormality has occurred, if the cooling function in the cooler 6 can be exerted to some extent, the cooling device 1 can operate while the electric expansion valve 4 has an abnormality. It becomes possible to continue the cooling operation.

  On the other hand, when the difference in the degree of superheat exceeds the continuously operable range, the control device 30 displays information on the abnormality of the electric expansion valve 4 on the display unit 35 and the cooling device 1. Stop operation.

  In any of the above cases, if the difference in the degree of superheat exceeds a predetermined abnormality occurrence value, the control device 30 displays the abnormality information on the display unit 35 and displays a buzzer or alarm. Alarm by lamp. Furthermore, the control device 30 also notifies an external centralized management means or the like that an abnormality has occurred in the electric expansion valve 4.

  As a result, it is possible to easily determine the abnormality of the electric expansion valve 4 itself, and it is possible to respond quickly before a critical state such as a cooling failure of the cooler 6 occurs. In particular, in the present embodiment, the control device 30 determines that the superheat degree assumed from the valve opening degree of the electric expansion valve currently grasped from the superheat degree obtained by calculating based on the actually detected temperature. Since the abnormality of the electric expansion valve 4 is determined when the distance is greater than or equal to the value, the abnormality of the electric expansion valve 4 can be grasped more reliably.

  In addition, when the abnormality of the electric expansion valve 4 is within a predetermined operable range, the control device 30 continues the operation of the cooling device 1, so that cooling according to the degree of abnormality of the electric expansion valve 4 is performed. The apparatus 1 can be operated. Therefore, when a minor abnormality that is within the range in which the electric expansion valve 4 can be operated occurs, it is possible to respond without stopping the operation, and thus avoid the disadvantage that the space to be cooled cannot be cooled. Will be able to.

  Further, when an abnormality has occurred in the electric expansion valve 4, the control device 30 holds information on the abnormality therein, so that the operator grasps the information on the abnormality at the next maintenance. Therefore, it is possible to quickly cope with the abnormality of the electric expansion valve 4.

  Further, since the control device 30 includes means for notifying the abnormality of the electric expansion valve 4 to the outside as described above, it becomes possible to notify the operator of the abnormality of the electric expansion valve 4 directly. It is possible to respond quickly.

  In this embodiment, the control device 30 determines the degree of superheat assumed from the valve opening degree of the electric expansion valve currently grasped from the degree of superheat obtained by calculating based on the actually detected temperature. When the electric expansion valve 4 is more than the predetermined value, the abnormality of the electric expansion valve 4 is determined. However, the abnormality of the electric expansion valve 4 may be determined based on the evaporation temperature of the cooler 6 besides this. .

  That is, the control device 30 stores in the ROM the evaporation temperature in the cooler 6 that is assumed in advance based on the opening degree of the electric expansion valve 4. The controller 30 outputs the evaporation temperature detected based on the evaporation temperature sensor 12 that detects the evaporation temperature of the refrigerant in the cooler 6 as needed, and the detected current evaporation temperature and the ROM as described above. The difference from the evaporation temperature of the cooler 6 that is assumed in advance is calculated based on the opening degree of the electric expansion valve 4 stored in the above. When the difference between the assumed evaporation temperature and the current evaporation temperature is equal to or greater than a predetermined abnormality occurrence value, it is determined that an abnormality has occurred in the electric expansion valve 4.

  Also in this case, when the difference in the evaporation temperature is not less than the predetermined abnormality occurrence value and is in a range where the operation can be continued, the control device 30 displays the electric expansion valve on the display unit 35. 4 is displayed, and the cooling device 1 is continuously operated.

  On the other hand, when the difference in the evaporation temperature exceeds the continuously operable range, the control device 30 displays information on the abnormality of the electric expansion valve 4 on the display unit 35 and the cooling device 1. Stop operation.

  In any of the above cases, the control device 30 displays the abnormality information on the display unit 35 and displays a buzzer or alarm when the difference in the evaporation temperature exceeds a predetermined abnormality occurrence value. Alarm by lamp. Furthermore, the control device 30 also notifies an external centralized management means or the like that an abnormality has occurred in the electric expansion valve 4.

  This also makes it possible to easily determine the abnormality of the electric expansion valve 4 itself, and to respond quickly before a critical state such as a cooling failure of the cooler 6 occurs. . In particular, in the present embodiment, the control device 30 operates when the evaporating temperature assumed from the valve opening degree of the electric expansion valve currently grasped is separated from the actually detected evaporating temperature by a predetermined value or more. Since the abnormality of the expansion valve 4 is determined, it is possible to grasp the abnormality of the electric expansion valve 4 more reliably.

  In addition, when the abnormality of the electric expansion valve 4 is within a predetermined operable range, the control device 30 continues the operation of the cooling device 1, so that cooling according to the degree of abnormality of the electric expansion valve 4 is performed. The apparatus 1 can be operated. Therefore, when a minor abnormality that is within the range in which the electric expansion valve 4 can be operated occurs, it is possible to respond without stopping the operation, and thus avoid the disadvantage that the space to be cooled cannot be cooled. Will be able to.

  Further, when an abnormality has occurred in the electric expansion valve 4, the control device 30 holds information on the abnormality therein, so that the operator grasps the information on the abnormality at the next maintenance. Therefore, it is possible to quickly cope with the abnormality of the electric expansion valve 4.

  Further, since the control device 30 includes means for notifying the abnormality of the electric expansion valve 4 to the outside as described above, it becomes possible to notify the operator of the abnormality of the electric expansion valve 4 directly. It is possible to respond quickly.

It is a refrigerant circuit figure of the cooling device to which this invention is applied. It is a schematic sectional drawing of the electric expansion valve in the cooling device of FIG. It is an electric circuit diagram of the control apparatus of a cooling device. It is an electric circuit diagram of an electric expansion valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Compressor 3 Condenser 4 Electric expansion valve 5 Liquid pipe solenoid valve 6 Cooler 7 Piping 8, 9 Blower 10 Refrigerant inlet side temperature sensor 11 Refrigerant outlet side temperature sensor 12 Evaporation temperature sensor 15 Stepping motor 16 Valve body 17 Main body 18 Valve seat 19 Inlet joint 20 Outlet joint 21 Flow path 25 Coil 26 Stator 27 Rotor 30 Controller 32 Pulse generation circuit 33 Drive circuit 35 Display section

Claims (4)

In the cooling device comprising a compressor, a condenser, an electric expansion valve, and a cooler connected in a circular pipe in order,
Control means for controlling the electric expansion valve, superheat degree detection means for detecting the superheat degree of the refrigerant in the cooler, and evaporation temperature detection means for detecting the evaporation temperature of the refrigerant in the cooler,
The control means controls the valve opening degree of the electric expansion valve based on the superheat degree of the refrigerant in the cooler detected by the superheat degree detection means,
The valve opening degree of the electric expansion valve known by the control means, the evaporation temperature of the refrigerant in the cooler detected by the evaporation temperature detecting means, and / or the refrigerant in the cooler detected by the superheat degree detecting means Cooling is characterized in that an abnormality of the electric expansion valve is determined on the basis of the degree of superheat, and when the abnormality is within a predetermined operable range, the operation is continued and information on the abnormality is retained. Control device for the device.   The control means is configured to determine whether the evaporation temperature and / or superheat degree assumed from the valve opening degree of the electric expansion valve currently grasped is the evaporation temperature and / or the refrigerant evaporation temperature in the cooler detected by the evaporation temperature detection means. 2. The control device for a cooling device according to claim 1, wherein when the degree of superheat of the refrigerant in the cooler detected by the superheat detection means is more than a predetermined value, it is determined that the electric expansion valve is abnormal. .   3. The control device for a cooling device according to claim 1, wherein the control means includes a predetermined display means, and displays the abnormality information on the display means.   The said control means outputs the information of the said abnormality to the exterior, The control apparatus of the cooling device of Claim 1, Claim 2 or Claim 3 characterized by the above-mentioned.

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