Refrigerant circuit device

Abstract

To excellently cool a facility to be cooled, and to prevent starting failure of a compressor.SOLUTION: A refrigerant circuit device 1 includes a refrigerant circuit 10 in which an evaporator 14 disposed in a refrigerator 32, a compressor 11 that and compresses a refrigerant evaporated by the evaporator 14, a condenser 12 that condenses the refrigerant compressed by the compressor 11, and an electronic expansion valve 13 that adiabatically expands the refrigerant condensed by the condenser 12 are sequentially connected by a refrigerant pipe line 15, and a control unit 20 that adjusts an opening degree of the electronic expansion valve 13 such that a degree of superheat approaches a predetermined target value. The control unit 20 increases the opening of the electronic expansion valve 13 when the duration of an abnormal condition in which the degree of superheat is lower than the target value and the inside temperature is higher than a preset reference temperature value exceeds a preset set time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a refrigerant circuit device. [Background technology]

[0002] For example, in a showcase that displays products in a cooled state, an electronic expansion valve and an evaporator are provided inside the case body, and a compressor and a condenser are provided outside the case body. The evaporator, compressor, condenser, and electronic expansion valve are connected in sequence by refrigerant pipes to form a refrigerant circuit in which refrigerant is sealed, and in the showcase, the refrigerant circulates through the refrigerant circuit to cool the storage chamber in the case body that stores the products (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-116202 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned showcase, it is known that the opening of the electronic expansion valve is adjusted so that the degree of superheat, which is the difference between the refrigerant temperature at the outlet of the evaporator and the refrigerant temperature at the inlet of the evaporator, approaches a target value in advance, and the opening of the electronic expansion valve is reduced as the degree of superheat approaches the target value.

[0005] The opening of the electronic expansion valve is reduced as the degree of superheat approaches the target value because the degree of superheat approaches the target value, which means that the degree of superheat is sufficiently small and the storage chamber is sufficiently cooled.

[0006] In the refrigerant circuit, if the amount of refrigerant flowing through the evaporator becomes insufficient due to solidification of moisture in the piping or dust particles in the piping, the degree of superheat may approach the target value. In such a case, reducing the opening of the electronic expansion valve may cause the compressor to malfunction, resulting in insufficient cooling of the storage chamber and even compressor failure.

[0007] In view of the above circumstances, an object of the present invention is to provide a refrigerant circuit device that can effectively cool equipment that requires refrigeration and prevent compressor start-up failures. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a refrigerant circuit device comprising: an evaporator disposed in equipment to be cooled; a compressor that sucks in and compresses the refrigerant evaporated by the evaporator; a condenser that condenses the refrigerant compressed by the compressor; and an electronic expansion valve that adiabatically expands the refrigerant condensed by the condenser, all of which are connected in sequence via refrigerant pipes; and a control unit that adjusts the aperture of the electronic expansion valve so that the degree of superheat, which is the difference between the refrigerant temperature at the evaporator outlet and the refrigerant temperature at the evaporator inlet, approaches a predetermined target value, the refrigerant circuit device further comprising temperature detection means that detects the temperature inside the equipment to be cooled, and the control unit increases the aperture of the electronic expansion valve when an abnormal state, in which the degree of superheat is lower than the target value and the temperature detected by the temperature detection means is higher than a predetermined reference temperature, continues for a predetermined set time.

[0009] Furthermore, in the refrigerant circuit device of the present invention, when the duration of the abnormal state exceeds the set time, the control unit keeps the electronic expansion valve in a fully open state until a predetermined operating time has elapsed. [Effects of the Invention]

[0010] According to the present invention, when the duration of an abnormal state in which the degree of superheat is lower than the target value and the temperature detected by the temperature detection means is higher than a predetermined reference temperature exceeds a predetermined set time, the control unit increases the opening of the electronic expansion valve, thereby eliminating the factors that cause pipe blockage, thereby achieving good cooling of equipment that requires cooling and preventing compressor startup failure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a refrigerant circuit device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the details of the valve opening adjustment process performed by the control unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a refrigerant circuit device according to the present invention will be described in detail below with reference to the accompanying drawings.

[0013] 1 is a schematic diagram showing a refrigerant circuit device according to an embodiment of the present invention. The refrigerant circuit device 1 shown here is configured to include a refrigerant circuit 10 and a control unit 20.

[0014] The refrigerant circuit 10 is a circuit configured by sequentially connecting a compressor 11, a condenser 12, an electronic expansion valve 13, and an evaporator 14 via a refrigerant pipe 15, and is filled with refrigerant.

[0015] The compressor 11 constitutes the refrigerator 31. The compressor 11 is driven in response to a command given from the control unit 20, and when driven, the compressor 11 sucks in a refrigerant, compresses it, and discharges it as a high-temperature, high-pressure refrigerant.

[0016] The condenser 12, like the compressor 11, constitutes the refrigerator 31. The condenser 12 condenses the refrigerant compressed by the compressor 11 by exchanging heat with the surrounding air.

[0017] The electronic expansion valve 13 is provided in the showcase (equipment requiring refrigeration) 32, and its inlet is connected to the condenser 12 through a refrigerant pipe 15. The opening degree of this electronic expansion valve 13 can be changed in response to a command given from the control unit 20, and adiabatically expands the refrigerant condensed in the condenser 12.

[0018] The evaporator 14 is installed in an air passage 33 in the showcase 32. This air passage 33 is in communication with a storage chamber 34 that stores products through an intake port and an outlet port (neither of which are shown), and air is circulated between the air passage 33 and the storage chamber 34 by driving a blower fan 35 installed in the air passage 33.

[0019] Although not shown in the figure, the storage room 34 stores products by having multiple product storage shelves arranged vertically on which products are placed, and air blown out from the air outlet is sucked into the air intake, forming an air curtain near the front opening of the storage room 34.

[0020] The evaporator 14 exchanges heat between the refrigerant adiabatically expanded by the electronic expansion valve 13 and the surrounding air, thereby evaporating the refrigerant and drawing it into the compressor 11. In the evaporator 14, the refrigerant evaporates to cool the air passing through the air passage 33, thereby cooling the products stored in the storage chamber 34.

[0021] The control unit 20 is connected to the above-mentioned compressor 11, electronic expansion valve 13 and blower fan 35, as well as to the inlet temperature sensor 14a, outlet temperature sensor 14b and inside temperature sensor (temperature detection means) 36.

[0022] The inlet temperature sensor 14a is installed near the inlet of the evaporator 14 in the refrigerant circuit 10. This inlet temperature sensor 14a detects the temperature of the refrigerant passing through the inlet of the evaporator 14, i.e., the inlet refrigerant temperature, and outputs the detection result to the control unit 20 as a detection signal.

[0023] The outlet temperature sensor 14b is installed near the outlet of the evaporator 14 in the refrigerant circuit 10. This outlet temperature sensor 14b detects the temperature of the refrigerant passing through the outlet of the evaporator 14, i.e., the outlet refrigerant temperature, and outputs the detection result to the control unit 20 as a detection signal.

[0024] The internal temperature sensor 36 is provided inside the storage chamber 34. The internal temperature sensor 36 detects the temperature of the air inside the storage chamber 34 (internal temperature), and outputs the detection result to the control unit 20 as a detection signal.

[0025] The control unit 20 comprehensively controls the operation of each part of the refrigerant circuit device 1 in accordance with programs and data stored in a memory unit 21 connected in the same way as the compressor 11, etc., and is characterized by having an input processing unit 20a, a calculation processing unit 20b, a judgment processing unit 20c, and a valve opening adjustment unit 20d.

[0026] The input processing unit 20a inputs and processes signals from each unit connected to the control unit 20, and in particular, inputs and processes detection signals from the inlet temperature sensor 14a, the outlet temperature sensor 14b, and the internal temperature sensor 36.

[0027] The calculation processing unit 20b calculates the degree of superheat by dividing the detection result (outlet refrigerant temperature) of the inlet temperature sensor 14a by the detection result (outlet refrigerant temperature) of the outlet temperature sensor 14b input and processed through the input processing unit 20a.

[0028] The determination processing unit 20c compares the degree of superheat calculated by the calculation processing unit 20b with a target value read from the storage unit 21, and determines whether the degree of superheat is equal to or greater than the target value. The target value is stored in the storage unit 21 as target value information, and serves as an index for adjusting the opening degree of the electronic expansion valve 13. The target value is set to, for example, 3 to 5 (°C).

[0029] The judgment processing unit 20c compares the detection result (inside cabinet temperature) of the inside cabinet temperature sensor 36 input and processed through the input processing unit 20a with a reference temperature read from the memory unit 21, and judges whether the inside cabinet temperature exceeds the reference temperature. Here, the reference temperature is stored in the memory unit 21 as reference temperature information, and is an index for judging whether an abnormality has occurred in the showcase 32.

[0030] The valve opening adjustment unit 20d adjusts the opening of the electronic expansion valve 13 by increasing or decreasing the opening.

[0031] The control unit 20 may be realized, for example, by having a processing device such as a CPU (Central Processing Unit) execute a program, i.e., by software, or by hardware such as an IC (Integrated Circuit), or by a combination of software and hardware.

[0032] In the refrigerant circuit device 1 having the above-described configuration, when cooling commodities stored in the showcase 32 (storage chamber 34), the control unit 20 drives the compressor 11 and the blower fan 35 and adjusts the opening of the electronic expansion valve 13 to a predetermined size via the valve opening adjustment unit 20d.

[0033] As a result, the refrigerant compressed by compressor 11 and condensed in condenser 12 is adiabatically expanded by electronic expansion valve 13, flows to evaporator 14, and evaporates by heat exchange with the air surrounding evaporator 14, and is then sucked into compressor 11. As the refrigerant evaporates in evaporator 14 in this way, the air circulating through storage chamber 34 and air passage 33 is cooled by driving blower fan 35, and the products in storage chamber 34 are cooled.

[0034] FIG. 2 is a flowchart showing the details of the valve opening adjustment process performed by the control unit 20 shown in FIG.

[0035] In this valve opening adjustment process, the control unit 20 inputs the inlet refrigerant temperature, outlet refrigerant temperature, and inside temperature from the inlet temperature sensor 14a, outlet temperature sensor 14b, and inside temperature sensor 36, respectively, via the input processing unit 20a (step S101).

[0036] Thereafter, the control unit 20 calculates the degree of superheat by subtracting the inlet refrigerant temperature from the outlet refrigerant temperature through the calculation processing unit 20b (step S102).

[0037] After calculating the degree of superheat, the control unit 20 reads the target value from the storage unit 21 via the determination processing unit 20c, and determines whether the degree of superheat is equal to or greater than the target value (step S103).

[0038] If it is determined that the degree of superheat is equal to or greater than the target value (step S103: Yes), the control unit 20 adjusts the opening of the electronic expansion valve 13 via the valve opening adjustment unit 20d so that the degree of superheat approaches the target value (step S104). More specifically, the opening of the electronic expansion valve 13 is increased or decreased depending on the difference between the degree of superheat and the target value, and the opening of the electronic expansion valve 13 is gradually decreased as the degree of superheat approaches the target value.

[0039] After executing step S104, the control unit 20 returns the procedure and ends the current processing. This causes the degree of superheat to transition closer to the target value.

[0040] On the other hand, if the degree of superheat is lower than the target value (step S103: No), the control unit 20 reads the reference temperature from the memory unit 21 via the judgment processing unit 20c, and determines whether the temperature inside the refrigerator exceeds the reference temperature (step S105).

[0041] If it is determined that the internal temperature is equal to or lower than the reference temperature (step S105: No), the control unit 20 adjusts the opening of the electronic expansion valve 13 via the valve opening adjustment unit 20d so that the degree of superheat approaches the target value (step S106). More specifically, the opening of the electronic expansion valve 13 is increased or decreased depending on the difference between the degree of superheat and the target value, and the opening of the electronic expansion valve 13 is gradually decreased as the degree of superheat approaches the target value.

[0042] After executing step S106, the control unit 20 returns the procedure and ends the current processing. This causes the degree of superheat to transition closer to the target value.

[0043] If it is determined in step S105 that the internal temperature is higher than the reference temperature (step S105: Yes), the control unit 20 determines whether the duration of the state in which the degree of superheat is lower than the target value and the internal temperature is higher than the reference temperature (abnormal state) has exceeded a preset time (step S107).

[0044] If the duration of the abnormal state has not exceeded the set time (step S107: No), the control unit 20 repeats the processes from step S103 onwards. On the other hand, if the duration of the abnormal state has exceeded the set time (step S107: Yes), the control unit 20 causes the valve opening adjustment unit 20d to fully open the electronic expansion valve 13 and waits for a predetermined operation time to elapse (steps S108 and S109). Here, the fully open state of the electronic expansion valve 13 in step S108 means that the opening of the electronic expansion valve 13 is set to the maximum value.

[0045] If the operating time has elapsed (step S109: Yes), the control unit 20 returns the opening of the electronic expansion valve 13 to its original size via the valve opening adjustment unit 20d (step S110), and then returns the procedure to end this processing.

[0046] When the degree of superheat is lower than the target value and the temperature inside the refrigerator exceeds the reference temperature, this is caused by an insufficient amount of refrigerant flowing through the evaporator 14. This phenomenon of an insufficient amount of refrigerant flowing is thought to be caused by solidified moisture or dust particles in the pipes, and by keeping the electronic expansion valve 13 fully open until the operating time has elapsed, it is possible to remove the solidified moisture (ice, etc.) or dust particles that are causing the pipes to clog.

[0047] As described above, according to the refrigerant circuit device 1 which is an embodiment of the present invention, when the duration of an abnormal state in which the degree of superheat is lower than the target value and the temperature inside the cabinet is higher than the reference temperature exceeds a set time, the control unit 20 causes the electronic expansion valve 13 to be fully open until a predetermined operating time has elapsed. This makes it possible to eliminate the factors that cause pipe clogging, to perform good cooling of the showcase 32, and to prevent failure of the compressor 11 to start up.

[0048] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this and various modifications can be made.

[0049] In the above-described embodiment, the control unit 20 keeps the electronic expansion valve 13 in a fully open state until the operation time has elapsed, but in the present invention, the opening degree of the electronic expansion valve may be increased to bring it close to a fully open state.

[0050] In the above-described embodiment, the internal temperature detected by the internal temperature sensor 36 is described as the temperature inside the equipment requiring refrigeration detected by the temperature detection means of the present invention, but in the present invention, various temperatures can be adopted as the temperature inside the equipment requiring refrigeration.

[0051] That is, the temperature of the air blown out from the air passage into the storage chamber (the controlled temperature) may be used as the temperature inside the equipment requiring cooling. When the controlled temperature is used as the temperature inside the equipment requiring cooling, the magnitude of the reference temperature is also appropriately changed. The value of this reference temperature may be expressed as the magnitude of the difference between the controlled temperature and the inlet refrigerant temperature.

[0052] In the above-described embodiment, the showcase 32 is given as an example of equipment requiring refrigeration, but in the present invention, the equipment requiring refrigeration may be something other than a showcase.

[0053] In the above-described embodiment, the compressor 11 and the condenser 12 constitute the refrigerator 31 and are arranged outside the showcase 32, but in the present invention, the compressor and the condenser may be arranged inside the showcase in the same manner as the evaporator. [Explanation of symbols]

[0054] 1... Refrigerant circuit device, 10... Refrigerant circuit, 11... Compressor, 12... Condenser, 13... Electronic expansion valve, 14... Evaporator, 14a... Inlet temperature sensor, 14b... Outlet temperature sensor, 15... Refrigerant pipe, 20... Control unit, 20a... Input processing unit, 20b... Calculation processing unit, 20c... Determination processing unit, 20d... Valve opening adjustment unit, 21... Memory unit, 31... Freezer, 32... Showcase, 33... Air passage, 34... Storage room, 35... Blower fan, 36... In-storage temperature sensor

Claims

1. a refrigerant circuit configured by sequentially connecting an evaporator disposed in equipment requiring cooling, a compressor for sucking and compressing the refrigerant evaporated by the evaporator, a condenser for condensing the refrigerant compressed by the compressor, and an electronic expansion valve for adiabatic expansion of the refrigerant condensed by the condenser, through a refrigerant pipe; a control unit that adjusts the opening degree of the electronic expansion valve so that a degree of superheat, which is a difference between a refrigerant temperature at an outlet of the evaporator and a refrigerant temperature at an inlet of the evaporator, approaches a predetermined target value; A refrigerant circuit device comprising: a temperature detection means for detecting the temperature inside the equipment requiring cooling; the control unit increases the opening of the electronic expansion valve when a predetermined set time elapses for an abnormal state in which the degree of superheat is lower than the target value and the temperature detected by the temperature detection means is higher than a predetermined reference temperature.

2. 2. The refrigerant circuit device according to claim 1, wherein the control unit, when the duration of the abnormal state exceeds the set time, keeps the electronic expansion valve in a fully open state until a predetermined operating time has elapsed.

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