TWI589821B - Freezer - Google Patents

Description

Freezer

The present invention relates to a refrigerating apparatus including a heat dissipating portion of an inverter, wherein the heat dissipating portion of the inverter cools an inverter device used for driving the compressor.

In recent years, a refrigerating apparatus has been proposed which aims to improve the efficiency of partial load, and controls the operating frequency of the compressor by means of a frequency converter. When the AC power supplied from the commercial power source is converted and applied to the compressor, the electrical loss in the rectifier circuit, the smoothing capacitor, and the inverter circuit is converted into heat (hereinafter referred to as inverter heat generation).

As a method of dissipating heat from the inverter, it is proposed to cool the heat sink of the inverter with a refrigerant (for example, refer to Patent Documents 1 and 2). Patent Document 1 proposes a refrigeration system in which a cooling refrigerant flow path is provided, which is branched from a refrigerant circulation flow path and then communicates with a compressor main body via an inverter. Patent Document 2 discloses a control method in which a bypass cooling circuit for cooling a heat radiating portion of a frequency converter is disposed in a refrigerant circuit, and a refrigerant that passes through a heat radiating portion of the frequency converter is controlled according to a temperature of a heat radiating portion of the frequency converter. the amount.

[Prior patent documents] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-21406

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-57875

As shown in the above-described freezers of Patent Documents 1 and 2, when the refrigerant in the heat radiating portion of the inverter is cooled by the refrigerant corresponding to the saturated gas temperature of the suction pressure, or the temperature of the sucked gas in the vicinity of the motor frame is mounted on the inverter. In the case of the affected part, when the intake gas temperature is low (for example, 0 ° C), condensation occurs in the inverter frame, and the function of the inverter circuit is impaired.

However, a method of cooling the heat radiating portion of the inverter by using a refrigerant gas of an economizer is conceivable. In this case, since the amount of refrigerant passing through the subcooler is controlled according to the temperature of the heat radiating portion of the inverter, when the amount of refrigerant that cools the inverter after passing through the subcooler is small, the subcooler cannot be effectively applied, and the performance is inevitable. Reduced situation.

The present invention has been made in order to solve the problems as described above, and an object of the present invention is to provide a refrigeration system that suppresses the performance degradation caused by the application of the supercooler while suppressing the occurrence of condensation on the inverter device.

The refrigeration system according to the present invention includes a refrigerant circuit that is connected to a compressor that compresses a refrigerant by a refrigerant pipe, a condenser that dissipates heat from the refrigerant discharged from the compressor, and cools the refrigerant that has flowed out of the condenser. a subcooler, an expansion device that depressurizes the refrigerant that has been supercooled in the subcooler, and a steam that absorbs heat and evaporates the refrigerant that is depressurized and expanded in the expansion device. The frequency converter is a frequency conversion device that drives the compressor; the heat dissipation part of the frequency converter is used to dissipate heat generated by the frequency conversion device; and the frequency converter cooling circuit including the overcooling circuit forms the slave subcooler and the expansion device The refrigerant flow path that flows into the compressor after the subcooler and the heat sink of the inverter are circulated; the flow rate adjustment device is installed in the inverter cooling circuit, and adjusts the flow rate of the refrigerant flowing into the heat sink of the inverter; The temperature detecting device detects the temperature of the heat radiating portion of the inverter as the heat sink temperature; the state detecting portion detects the state of the refrigerant flowing to the subcooler; and the control device is based on the temperature detecting device of the inverter The detected heat sink temperature and the state of the refrigerant flowing to the subcooler detected by the state detecting unit, and controlling the operation of the flow rate adjusting device; the control device includes: a temperature determining unit that determines whether the heat sink temperature is Located in the target temperature range; the superheat calculation unit calculates the flow from the state of the refrigerant detected by the state detecting unit to the subcooler In the case where the temperature determination unit determines that the heat radiation unit temperature is within the target temperature range, the opening degree control unit controls the opening size of the flow rate adjustment device so that the superheat degree calculated by the superheat degree calculation unit becomes the target overheating degree. In the case where the temperature determining unit determines that the heat radiating portion temperature is outside the target temperature range, the opening size of the flow rate adjusting device is controlled so that the heat radiating portion temperature is within the target temperature range.

According to the refrigeration apparatus of the present invention, when the temperature of the heat dissipating portion is within the target temperature range, the opening size of the flow rate adjusting device is controlled according to the degree of superheat, and when the temperature of the heat dissipating portion is outside the target temperature range, the temperature of the heat dissipating portion is used. Controlling the opening size of the flow regulating device, thereby suppressing the performance degradation caused by insufficient application of the subcooler while suppressing the coldness of the inverter device But the condensation of time has happened.

1, 100, 200‧‧‧ freezer

1A‧‧‧ refrigerant circuit

2‧‧‧Compressor

2a‧‧‧Mechanical Department

3‧‧‧ oil separator

4‧‧‧Condenser

5‧‧‧Overcooler

6‧‧‧Expansion device

7‧‧‧Evaporator

10, 210‧‧‧Inverter cooling circuit

10A‧‧‧Overcooling circuit

10B‧‧‧ bypass cooling circuit

11‧‧‧Flow adjustment device

11A‧‧‧1st expansion valve

11B‧‧‧2nd expansion valve

11C‧‧‧Opening and closing valve

12‧‧‧Inverter heat sink

20‧‧‧Inverter

31‧‧‧Dissipation temperature detection device

32a, 132a‧‧‧ refrigerant temperature detecting device

32b‧‧‧Intermediate pressure detecting device

33‧‧‧Inhalation temperature detecting device

34‧‧‧Inhalation pressure detecting device

40‧‧‧Control device

41‧‧‧ Temperature Judgment Department

42‧‧‧Superheat calculation unit

43‧‧‧ Opening size control department

SH‧‧‧Superheat

Tr‧‧‧heat section temperature

Tr1‧‧‧ lower limit

Tru‧‧‧ upper limit

Trus‧‧‧2nd upper limit

Fig. 1 is a refrigerant circuit diagram of a refrigeration system according to a first embodiment of the present invention.

Fig. 2 is a functional block diagram showing an example of a control device of the refrigeration system of Fig. 1.

Fig. 3 is a flow chart showing an operation example of the freezing apparatus of Fig. 1.

Fig. 4 is a refrigerant circuit diagram of the refrigeration system according to the second embodiment of the present invention.

Fig. 5 is a refrigerant circuit diagram of the refrigeration system according to the third embodiment of the present invention.

Fig. 6 is a flow chart showing an operation example of the freezing apparatus of Fig. 5.

First embodiment

Hereinafter, an embodiment of the refrigeration system of the present invention will be described with reference to the drawings. Fig. 1 is a refrigerant circuit diagram of a refrigeration system according to a first embodiment of the present invention. As shown in Fig. 1, the refrigeration system 1 includes a compressor 2, an oil separator 3, a condenser 4, a subcooler 5, an expansion device 6, and an evaporator 7, and these components are connected by a refrigerant pipe to constitute a refrigerant circulated by the refrigerant. Loop 1A.

The compressor 2 is composed of, for example, a screw compressor, and is a refrigerant that is compressed and discharged. The compressor 2 has a mechanical portion 2a that houses a compression element and an electric element in a hermetic container. Further, the type of the compressor 2 is not limited to a screw compressor, and may be, for example, a vane compressor, a rotary compressor, or the like, or may be a single Segment or multi-stage compressors, etc. The compressor 2 is driven by a frequency conversion device 20. The oil separator 3 separates the refrigerating machine oil contained in the refrigerant discharged from the compressor 2, and the separated refrigerating machine oil is returned to the compressor 2. The condenser 4 is a heat exchanger that dissipates and cools the refrigerant that has been separated from the oil in the oil separator 3.

The subcooler 5 is an intercooling heat exchanger that supercools the refrigerant flowing out of the condenser 4. The expansion device 6 is constituted by, for example, an electronic expansion valve, and is configured to reduce the expansion of the refrigerant that has been supercooled by the subcooler 5. The evaporator 7 is a heat exchanger that absorbs heat and evaporates the refrigerant that has been depressurized and expanded by the expansion device 6.

Further, the refrigeration system 1 includes an inverter device 20 that drives the compressor 2, and an inverter heat dissipation portion 12 that dissipates heat generated by the inverter device 20. The inverter device 20 is integrally formed with the inverter heat radiating portion 12, and the inverter heat radiating portion 12 is provided integrally with the compressor 2. For example, in the compressor 2, the inverter heat radiating portion 12 is formed outside the sealed container of the mechanical portion 2a, and the heat generating element such as the inverter device 20 is placed on the inverter heat radiating portion 12 together with the rectifier circuit and the smoothing capacitor. The inverter heat radiating portion 12 is constituted by, for example, a fin that forms a flow path, and the inverter device 20 is cooled by circulating a refrigerant.

The refrigerating apparatus 1 includes an inverter cooling circuit 10 for circulating a refrigerant to the inverter heat radiating portion 12, and a flow rate adjusting device 11 which is provided in the inverter cooling circuit 10 and adjusts the flow rate of the refrigerant flowing into the heat radiating portion 12 of the inverter. . The inverter cooling circuit 10 has a supercooling circuit 10A and a bypass cooling circuit 10B. The supercooling circuit 10A forms a refrigerant flow path that branches from the subcooler 5 and the expansion device 6, and flows through the subcooler 5 and the inverter heat radiating portion 12, and then flows into the compressor 2. Moreover, the refrigerant from the subcooler 5 to the expansion device 6 A part of the branch is depressurized by the first expansion valve 11A, and then flows into the inverter heat radiating portion 12. The inverter heat radiating portion 12 performs heat exchange by the refrigerant, thereby cooling the inverter heat radiating portion 12, and then supplying the refrigerant gas to the intermediate pressure space of the compressor 2.

The bypass cooling circuit 10B is formed as a refrigerant flow path that branches between the subcooler 5 and the expansion device 6 and flows through the inverter heat dissipation portion 12 to flow into the compressor 2. The bypass cooling circuit 10B branches a part of the refrigerant from the subcooler 5 to the expansion device 6, and depressurizes the second expansion valve 11B, and then flows into the inverter heat radiating portion 12. Then, the inverter heat radiating portion 12 is cooled by heat exchange with the refrigerant, and then merges with the refrigerant gas that has passed through the first expansion valve 11A, and then supplies the refrigerant gas to the intermediate pressure space of the compressor 2.

That is, the inverter cooling circuit 10 includes the subcooling circuit 10A and the bypass cooling circuit 10B that allow the refrigerant to flow to the inverter heat radiating portion 12. Further, in the cooling of the inverter heat radiating portion 12, since the refrigerant radiating portion 12 is cooled by the refrigerant flowing through the intermediate pressure space (for example, refrigerant gas of 20 to 30 ° C), condensation on the heat radiating portion 12 of the inverter can be suppressed. occur. Further, in the inverter cooling circuit 10, when the subcooling circuit 10A is insufficiently cooled by the inverter heat radiating portion 12, the refrigerant liquid is also caused to flow to the bypass cooling circuit 10B side, and the cooling shortage can be eliminated.

The flow rate adjusting device 11 is provided in the inverter cooling circuit 10, and adjusts the flow rate of the refrigerant flowing to the inverter heat radiating portion 12. The flow rate adjusting device 11 includes a first expansion valve 11A provided on the supercooling circuit 10A side, a second expansion valve 11B provided in the bypass cooling circuit 10B, and an opening and closing valve 11C. The first expansion valve 11A is constituted by, for example, an electronic expansion valve, and is provided between the branch point between the subcooler 5 and the expansion device 6 and the subcooler 5. By adjusting the first expansion valve The opening size of 11A controls the flow rate of the refrigerant flowing from the subcooler 5 to the inverter heat radiating portion 12 on the supercooling circuit 10A side.

The second expansion valve 11B is constituted by, for example, an electronic expansion valve, and is provided between the branch point between the subcooler 5 and the expansion device 6 and the inverter heat radiation portion 12. The on-off valve 11C is provided between the branch point between the subcooler 5 and the expansion device 6 and the second expansion valve 11B. The second expansion valve 11B and the opening and closing valve 11C constitute a bypass flow rate adjusting device that controls the flow rate of the refrigerant in the bypass cooling circuit 10B. Further, although the second expansion valve 11B and the opening and closing valve 11C are separately provided as an example, the second expansion valve 11B may be a fully open electronic expansion valve, and the opening and closing valve 11C may be omitted. By adjusting the opening size of the second expansion valve 11B, the flow rate of the refrigerant flowing to the inverter heat radiating portion 12 on the supercooling circuit 10B side is controlled. Further, by controlling the opening and closing operation of the opening and closing valve 11C, the flow of the refrigerant to the bypass cooling circuit 10B is controlled.

An example of the operation of the freezing apparatus 1 will be described using FIG. The refrigerant compressed by the compressor 2 is discharged from the compressor 2, and is separated into refrigerant gas and oil after the oil separator 3, and then flows into the condenser 4. The refrigerant gas system that has flowed into the condenser 4 is condensed to become a refrigerant liquid, and is subjected to heat exchange in the subcooler 5 to be supercooled. The refrigerant that has been supercooled is sent to the evaporator 7 after the expansion device 6 is stepped down, and the refrigerant sent to the evaporator 7 exchanges heat with, for example, air to become a refrigerant gas, and then flows into the compressor 2.

Further, a part of the refrigerant from the subcooler 5 to the expansion device 6 is branched to the inverter cooling circuit 10. The refrigerant branched to the subcooling circuit 10A side of the inverter cooling circuit 10 is depressurized in the first expansion valve 11A, and after the subcooler 5 performs heat exchange between the refrigerants, it becomes a refrigerant gas. Then, the refrigerant After the inverter heat sink 12 cools the inverter unit 20, it flows into the intermediate pressure space of the compressor 2. Further, the refrigerant branched into the bypass cooling circuit 10B of the inverter cooling circuit 10 passes through the second expansion valve 11B and the opening and closing valve 11C, and cools the inverter heat radiating portion 12. Then, the refrigerant is merged with the refrigerant gas flowing through the subcooling circuit 10A, and then injected into the intermediate pressure space of the compressor 2.

The operation of the above-described freezing device 1 is controlled by the control device 40, and the control device 40 is controlled based on information detected by various sensors. Specifically, the refrigeration system 1 includes a heat radiation portion temperature detecting device 31, a state detecting device (a refrigerant temperature detecting device 32a, an intermediate pressure detecting device 32b), a suction temperature detecting device 33, a suction pressure detecting device 34, and the like.

The heat sink temperature detecting device 31 detects the temperature of the heat sink portion 12 of the inverter. The refrigerant temperature detecting device 32a and the intermediate pressure detecting device 32b function as state detecting devices for detecting the state of the refrigerant flowing through the inverter cooling circuit 10. The refrigerant temperature detecting device 32a detects the temperature of the refrigerant flowing through the subcooler 5, and detects the temperature before flowing into the inverter heat radiating portion 12. The intermediate pressure detecting device 32b detects the pressure of the intermediate pressure space in the middle of the compression portion of the compressor 2. The suction temperature detecting device 33 detects the temperature of the refrigerant gas sucked by the compressor 2. The suction pressure detecting device 34 detects the pressure of the refrigerant gas sucked by the compressor 2. The detected values detected by these detecting means are output to the control means 40.

Fig. 2 is a functional block diagram showing an example of a control device of the refrigeration system of Fig. 1. The control device 40 of Fig. 2 is constituted by a hardware such as a circuit component that realizes its functions, or an arithmetic device such as a microcomputer or a CPU, and a software executed thereon. The control device 40 is based on the temperature detection in the heat sink The detected value detected by the measuring device 31, the refrigerant temperature detecting device 32a, and the intermediate pressure detecting device 32b controls the flow rate of the refrigerant flowing to the inverter cooling circuit 10, and includes a temperature determining portion 41, a superheat calculating portion 42, and an opening size control. Part 43.

The temperature determining unit 41 determines whether or not the heat radiating portion temperature Tr detected by the heat radiating portion temperature detecting device 31 is within the target temperature range. The target temperature range is, for example, set to 25 ° C for the lower limit value Tr1 and set to 40 ° C for the upper limit value Tru. The temperature determination unit 41 determines whether or not the heat radiation portion temperature Tr is within the target temperature range, whether it exceeds the target temperature range upper limit value Tru, or whether it is lower than the target temperature range lower limit value Tr1. The superheat degree calculation unit 42 calculates the superheat degree SH of the refrigerant gas flowing through the subcooler 5 from the temperature detected by the refrigerant temperature detecting device 32a and the pressure detected by the intermediate pressure detecting device 32b.

The opening size control unit 43 controls the operation of the flow rate adjusting device 11 based on the determination result of the temperature determining unit 41. The opening size control unit 43 controls the opening size of the flow rate adjusting device 11 so that the superheat degree SH becomes the target superheat degree when the temperature determining unit 41 determines that the heat radiating portion temperature Tr is within the target temperature range. At this time, the opening size control unit 43 allows the refrigerant in the supercooling circuit 10A side to flow in the inverter cooling circuit 10, and sets the opening and closing valve 11C on the side of the bypass cooling circuit 10B to the closed state, thereby causing the refrigerant to pass. The inflow of the bypass cooling circuit 10B is stopped. Further, the opening size control unit 43 controls the opening size of the first expansion valve 11A on the supercooling circuit 10A side so that the superheat degree SH becomes the target superheat degree.

On the other hand, when the temperature determining unit 41 determines that the heat radiating portion temperature Tr is less than the target temperature range lower limit value Tr1 (for example, 25 ° C), the meaning is changed. The cooling of the radiator heat sink 12 is excessive. The opening size control unit 43 switches the control target from the superheat degree SH to the heat radiation unit temperature Tr, and controls the opening size of the first expansion valve 11A so that the heat radiation portion temperature Tr becomes equal to or higher than the lower limit value Tr1 of the target temperature range.

In addition, when the temperature determining unit 41 determines that the heat radiating portion temperature Tr is larger than the target temperature range upper limit value Tru, the opening size control unit 43 determines that the cooling of the inverter heat radiating portion 12 is insufficient. The opening size control unit 43 switches the control target from the superheat degree SH to the heat radiating portion temperature Tr, and controls the opening size of the flow rate adjusting device 11 so that the heat radiating portion temperature Tr is within the target temperature range. At this time, the opening size control unit 43 opens the opening and closing valve 11C, and causes the refrigerant to flow to both the supercooling circuit 10A and the bypass cooling circuit 10B of the inverter cooling circuit 10. In this case, the temperature determination unit 41 is changed to a second upper limit value Trus (for example, 35° C.) lower than the upper limit value Tru of the first target temperature range.

Then, the opening size control unit 43 controls the opening size of the second expansion valve 11B to be increased to the heat radiating portion temperature Tr when the temperature determining unit 41 determines that the heat radiating portion temperature Tr exceeds the second upper limit value Trus after the change. The second upper limit value is less than Trus. Then, the opening size control unit 43 maintains the opening size of the second expansion valve 11B to be smaller than the target temperature range lower limit value Tr1 when the heat radiation portion temperature Tr is equal to or lower than the second upper limit value Trus. Then, when the heat radiation portion temperature Tr becomes smaller than the target temperature range lower limit value Tr1, the opening size control unit 43 gradually reduces the opening size of the second expansion valve 11B. Then, when the opening size of the second expansion valve 11B is the smallest opening size, the opening size control unit 43 closes the opening and closing valve 11C, and stops the circulation of the refrigerant in the bypass cooling circuit 10B.

Fig. 3 is a flow chart showing an operation example of the freezing apparatus of Fig. 1. Further, the processing shown in the flowchart of FIG. 3 is implemented every arbitrarily set control time interval. First, the superheat degree SH of the refrigerant gas in the gas temperature detecting portion in the subcooler 5 is calculated based on the temperature detected by the refrigerant temperature detecting device 32a and the pressure detected by the intermediate pressure detecting device 32b. The opening size of the first expansion valve 11A is controlled so that the superheat degree SH becomes the target superheat degree (step ST11).

Here, the temperature determination unit 41 determines whether or not the heat radiation portion temperature Tr of the inverter heat radiation portion 12 is equal to or lower than the upper limit value Tru of the target temperature range (step ST12). When the heat radiating portion temperature Tr is equal to or lower than the target temperature range upper limit value Tru, it is determined that the temperature of the inverter device 20 is in a stable operating state, and when the heat radiating portion temperature Tr exceeds the target temperature range upper limit value Tru, It is judged that the inverter device 20 is in an overheated operation state.

<Regarding steady state operation state (steps ST13 to ST16)>

When it is determined that the heat radiation portion temperature Tr is in the steady state operation state equal to or lower than the target temperature range upper limit value Tru (YES in step ST12), the on-off valve 11C is closed, and the circulation of the refrigerant in the bypass cooling circuit 10B is stopped (step ST13). In addition, the operating state is maintained in the case of a steady state operation state. Then, the control device 40 determines whether or not the heat radiation portion temperature Tr is equal to or greater than the target temperature range lower limit value Tr1 (step ST14).

When the heat radiating portion temperature Tr is equal to or greater than the target temperature range lower limit value Tr1 (YES in step ST14), the heat radiating portion temperature Tr is within the target temperature range, and it is judged that it is in an appropriate state and maintained in the operating state. On the other hand, in the heat dissipating portion temperature Tr is less than the target temperature range lower limit value Tr1 In the case (NO in step ST14), the inverter device 20 is excessively cooled, and it is determined that there is a possibility that dew condensation occurs. In this case, the control target of the first expansion valve 11A is changed from the superheat degree SH to the heat radiation part temperature Tr (step ST15). Then, the opening size of the first expansion valve 11A is controlled so that the heat radiation portion temperature Tr becomes equal to or higher than the lower limit value Tr1 of the target temperature range (steps ST14 to ST16). In this manner, when the heat radiating portion temperature Tr is equal to or lower than the upper limit value Tru of the target temperature range, the control target is switched from the superheat degree SH to the heat radiating portion temperature Tr, and the cooling can be appropriately cooled so that the cooling of the inverter heat radiating portion 12 does not become over.

<overheated operation state>

When it is determined that the heat radiating portion temperature Tr exceeds the overheating operation state of the target temperature range upper limit value Tru (NO in step ST12), the control target is changed from the superheat degree SH to the heat radiating portion temperature Tr. Further, the upper limit value Tru of the target temperature range is set to be smaller than the initial second upper limit value Trus (for example, 35 ° C) (step ST21). Then, the opening and closing valve 11C is opened (step ST22), and the refrigerant flows to both the supercooling circuit 10A and the bypass cooling circuit 10B. Further, the opening size of the second expansion valve 11B is controlled to be large (step ST23). It is determined whether or not the heat dissipating portion temperature Tr is equal to or less than the second upper limit value Trus (step ST24), and the opening size of the second expansion valve 11B is increased to be equal to or lower than the second upper limit value Trus (steps ST23 and ST24).

On the other hand, when the heat radiation portion temperature Tr is equal to or less than the second upper limit value Trus (YES in step ST24), it is determined that the heat radiation portion temperature Tr is equal to or greater than the lower limit value Tr1 of the target temperature range (step ST25). When it is determined that the heat radiating portion temperature Tr is less than the target temperature range lower limit value Tr1 (NO in step ST25), since the inverter heat radiating portion 12 is excessively cooled, the opening of the second expansion valve 11B is made large. Smaller and smaller (steps ST25, ST29).

When the heat radiating portion temperature Tr is equal to or greater than the target temperature range lower limit value Tr1 (YES in step ST25), the opening size of the second expansion valve 11B is maintained (step ST26). At this time, it is judged whether or not the opening size of the second expansion valve 11B is the smallest opening size (step ST27). When the opening size of the second expansion valve 11B is not the smallest opening size, the opening size adjustment of the second expansion valve 11B described above is performed (steps ST25 to ST27). When the size of the opening of the electronic expansion valve is the smallest (YES in step ST27), it is judged that the opening and closing valve 11C is closed and the refrigerant does not flow to the side of the bypass cooling circuit 10B, and the temperature Tr of the heat radiating portion does not exceed the target temperature range. In the state of the upper limit value Tru, the on-off valve 11C is closed (step ST28). As described above, the processing of steps ST21 to ST29 is performed every control time interval. In the case of the overheating operation, the size of the opening of the second expansion valve 11B is adjusted as an example. However, the opening size of the second expansion valve 11B may be adjusted not only by the opening size of the second expansion valve 11B but also by the opening of the first expansion valve 11A.

According to the first embodiment, when the heat radiation portion temperature Tr is within the target temperature range, the opening size of the flow rate adjusting device 11 is controlled according to the degree of superheat SH, and when the heat radiating portion temperature Tr is outside the target temperature range, The opening size of the flow rate adjusting device 11 is controlled in accordance with the heat radiating portion temperature Tr. Thereby, it is possible to suppress the occurrence of dew condensation at the time of cooling of the inverter device 20 while suppressing a decrease in capability caused by insufficient application of the subcooler 5. Further, in the cooling of the inverter heat radiating portion 12, the refrigerant flowing in the intermediate pressure space is used, whereby the refrigerant of the cooled inverter device 20 is prevented from being obstructed by the suction gas, and the performance can be improved.

In the steady state operation state, the inverter heat radiating portion 12 is cooled by the refrigerant gas that has passed through the subcooler 5 flowing into the intermediate pressure space, whereby the temperature difference between the outside air and the inverter heat radiating portion 12 is made small, and the temperature difference can be suppressed. The occurrence of condensation. Further, in the overheated operation state, by controlling the temperature of the inverter heat radiating portion 12 to be near the upper limit value Tru of the target temperature range, the inverter heat radiating portion 12 is cooled without excessive cooling, and the external air and the inverter are caused. The temperature difference of the heat radiating portion 12 becomes small, and the occurrence of dew condensation can be suppressed.

Further, in the case of the overheating operation state in which the heat radiation portion temperature Tr exceeds the target temperature range upper limit value Tru, the refrigerant heat sink portion 12 is further cooled by using the refrigerant liquid on the bypass cooling circuit 10B side, whereby the heat radiating portion can be provided. The temperature Tr becomes equal to or lower than the upper limit value Tru of the target temperature range and the upper limit value Tru of the target temperature range. Therefore, excessive cooling of the inverter heat radiating portion 12 can be suppressed, and the temperature difference between the heat radiating portion 12 of the inverter and the outside air can be made small, and the occurrence of dew condensation can be suppressed.

In addition, even if the heat radiating portion temperature Tr is smaller than the lower limit value Tr1 of the target temperature range and is in a state of excessive cooling, the control is switched from the control of the degree of superheat SH to the control according to the heat radiating portion temperature Tr, thereby avoiding the ease. The state of condensation has occurred.

Further, in the case where the inverter cooling circuit 10 has not only the overcooling circuit 10A but also the bypass cooling circuit 10B, the heat radiating portion temperature Tr can be cooled to the target temperature range in advance in the overheating operation state.

Second embodiment

Fig. 4 is a refrigerant circuit diagram of the refrigeration system according to the second embodiment of the present invention, and the refrigeration system 100 will be described with reference to Fig. 4 . In addition, in the first In the freezing apparatus 100 of the drawing, the same components as those of the freezing apparatus 1 of the first embodiment are denoted by the same reference numerals, and their description will be omitted. The difference between the freezing device 100 of Fig. 4 and the freezing device 1 of Fig. 1 is the mounting position of the refrigerant temperature detecting device 132a.

In the refrigeration system 100 of Fig. 4, the refrigerant temperature detecting device 132a is attached to a position at which the temperature of the refrigerant flowing out of the inverter heat radiating portion 12 is detected. Further, the outflow temperature sensor is disposed at a position before the bypass cooling circuit 10B merges. Further, the superheat degree calculation unit 42 calculates the superheat degree SH of the refrigerant gas using the refrigerant temperature detected by the refrigerant temperature detecting device 132a. The opening size control unit 43 controls the first expansion valve 11A to have a superheat degree SH to a target superheat degree in a steady state operation.

According to the second embodiment, as in the first embodiment, it is possible to suppress the occurrence of dew condensation during cooling of the inverter device 20 while suppressing performance degradation caused by insufficient application of the subcooler 5. Further, since the first expansion valve 11A is controlled in accordance with the temperature of the refrigerant after cooling the inverter heat radiating portion 12, the range in which the control is operable during the steady-state operation can be further expanded. Further, since the amount of the liquid injection refrigerant is also reduced during the overheating operation, the performance deterioration in the overheated operation state can be suppressed.

Third embodiment

Fig. 5 is a refrigerant circuit diagram of a refrigeration system according to a third embodiment of the present invention, and a refrigeration system 200 will be described with reference to Fig. 5. In the refrigerating apparatus 200 of the fifth embodiment, the same components as those of the freezing apparatus 1 of the first embodiment are denoted by the same reference numerals, and their description will be omitted. The difference between the freezing device 200 of Fig. 5 and the freezing device 1 of Fig. 1 is the configuration of the inverter cooling circuit.

The inverter cooling circuit 210 of Fig. 5 is constituted by the subcooling circuit 10A without using the bypass cooling circuit 10B. Therefore, the opening size control unit 43 of the control device 40 controls the opening size of the first expansion valve 11A of the flow rate adjusting device 11.

Fig. 6 is a flow chart showing an example of control of the refrigeration system according to the third embodiment of the present invention. Further, the processing shown in the flowchart of Fig. 6 is executed every control time interval that is arbitrarily set. In the flowchart of Fig. 6, the same reference numerals are given to the same steps as those of the flowchart of Fig. 3, and the description thereof will be omitted. In the steady-state operation state, the same control is performed except that there is no step ST13, and steps ST31 to ST37 for controlling the superheat operation state will be described below.

<overheated operation state>

The opening size control unit 43 of the control device 40 changes the control target of the first expansion valve 11A from the superheat degree SH to the heat radiation unit temperature Tr (step ST31). Since the heat radiating portion temperature Tr is higher than the upper limit value Tru of the target temperature range, the opening size of the first expansion valve 11A is controlled to be large (step ST32). Then, it is determined whether or not the heat radiation portion temperature Tr is equal to or lower than the target temperature range upper limit value Tru (step ST33). When it is determined that the heat radiating portion temperature Tr exceeds the target temperature range upper limit value Tru (NO in step ST33), since the inverter heat radiating portion 12 is in a state of insufficient cooling, the opening size of the first expansion valve 11A is controlled to be large. The heat radiating portion temperature Tr is equal to or lower than the upper limit value Tru of the target temperature range (steps ST32 and ST33).

On the other hand, when it is determined that the heat radiating portion temperature Tr is equal to or less than the target temperature range upper limit value Tru (YES in step ST33), the heat radiating portion temperature is determined. Whether the degree Tr is equal to or greater than the target temperature range lower limit value Tr1 (step ST34). When it is judged that the heat radiating portion temperature Tr is less than the target temperature range lower limit value Tr1 (NO in step ST34), since the inverter heat radiating portion 12 is excessively cooled, the opening size of the first expansion valve 11A is controlled to be larger than the current one. The opening size is smaller (step ST37). In addition, the opening size of the first expansion valve 11A is controlled to be smaller than the lower limit Tr1 of the target temperature range (steps ST34 and ST37).

On the other hand, when the heat radiating portion temperature Tr is equal to or greater than the target temperature range lower limit value Tr1 (YES in step ST34), it is determined whether or not the superheat degree SH is more stable than the steady state in order to determine whether or not the steady state operating state control can be performed. The target superheat is greater (step ST35). When the superheat degree SH is larger than the target superheat degree (YES in step ST35), it is determined that the supercooler 5 is not applied, and the control target of the first expansion valve 11A is changed from the heat radiating portion temperature Tr to the steady state operating state. The degree of superheat SH (step ST36). On the other hand, when the superheat degree SH is smaller than the control target superheat degree, the control is continued in accordance with the control of the heat radiating portion temperature Tr (steps ST33 to ST35).

According to the third embodiment, as in the first embodiment, the control of the first expansion valve 11A is changed in the overheated operation state, that is, when the temperature of the inverter heat radiation portion 12 exceeds the target temperature range upper limit value Tru. The target is such that the temperature of the heat sink 12 of the inverter is below the upper limit value Tru of the target temperature range and near the upper limit value Tru of the target temperature range. Therefore, excessive cooling of the inverter heat radiating portion 12 can be suppressed, and the temperature difference between the inverter heat radiating portion 12 and the outside air can be made small. Further, since there is no cooling circuit for borrowing liquid, the refrigerant circuit and control can be simplified.

11‧‧‧Flow adjustment device

11A‧‧‧1st expansion valve

11B‧‧‧2nd expansion valve

11C‧‧‧Opening and closing valve

31‧‧‧Dissipation temperature detection unit

32a‧‧‧Refrigerant temperature detecting device

32b‧‧‧Intermediate pressure detecting device

40‧‧‧Control device

41‧‧‧ Temperature Judgment Department

42‧‧‧Superheat calculation unit

43‧‧‧ Opening size control department

SH‧‧‧Superheat

Tr‧‧‧heat section temperature

Claims (10)

A refrigerating apparatus comprising: a refrigerant circuit in which a compressor that compresses a refrigerant is connected by a refrigerant pipe, a condenser that dissipates heat from the refrigerant discharged from the compressor, and a condenser that supercools the refrigerant flowing out of the condenser a subcooler, an expansion device that depressurizes and expands the refrigerant that has been supercooled in the subcooler, and an evaporator that absorbs heat and evaporates the refrigerant that is depressurized and expanded in the expansion device; the inverter device drives the a compressor; a heat dissipating portion of the inverter, heat dissipating heat generated by the inverter device; and a frequency converter cooling circuit including a subcooling circuit, the subcooling circuit forming a branch from the subcooler and the expansion device, and a refrigerant flow path that flows into the compressor after the subcooler flows through the heat sink of the inverter; and a flow rate adjusting device is provided in the inverter cooling circuit to adjust a flow rate of the refrigerant flowing into the heat radiating portion of the inverter; The device temperature detecting device detects the temperature of the heat dissipating portion of the inverter as the heat dissipating portion temperature, and the state detecting portion detects the cold flowing to the subcooler And a control device that controls the flow rate based on the temperature of the heat dissipating portion detected by the inverter temperature detecting device and the state of the refrigerant flowing to the subcooler detected by the state detecting portion Adjusting the action of the device; the control device includes: a temperature determining unit that determines whether the temperature of the heat dissipating portion is within a target temperature range; The superheat calculation unit calculates the degree of superheat of the refrigerant flowing to the subcooler from the state of the refrigerant detected by the state detecting unit, and the opening size control unit determines the temperature of the heat dissipating portion by the temperature determining unit. When the temperature is within the target temperature range, the opening size of the flow rate adjusting device is controlled such that the superheat degree calculated by the superheat degree calculating unit becomes the target superheat degree, and the temperature determining unit determines that the heat dissipating unit temperature is outside the target temperature range. In the case, the opening size of the flow regulating device is controlled such that the heat sink temperature is within the target temperature range. The refrigerating apparatus of claim 1, wherein the control device controls the opening size of the flow regulating device to be small when it is determined that the heat dissipating portion temperature is lower than a lower limit of the target temperature range. The refrigerating apparatus according to claim 1, wherein the opening size control unit controls the opening size of the flow rate adjusting device to be larger when it is determined that the heat dissipating portion temperature is greater than a target temperature range upper limit value. The freezing device of claim 1, wherein the control device controls the opening of the flow regulating device to be smaller when it is determined that the temperature of the heat dissipating portion is lower than a lower limit of the target temperature range, and When the temperature of the heat radiating portion is greater than the upper limit of the target temperature range, the opening size of the flow rate adjusting device is controlled to be large. The refrigerating apparatus of claim 4, wherein the opening size control unit controls the temperature of the heat dissipating unit to be smaller than a target temperature range upper limit after the opening size of the flow regulating device is increased, the overheating When the degree becomes greater than the target superheat degree, the control target is changed from the heat radiating portion temperature to the superheat degree. The refrigerating device of any one of claims 1 to 5, wherein the inverter cooling circuit comprises a branch from the subcooler and the expansion device, and is connected to the compressor via the subcooler. a bypass cooling circuit; the flow regulating device has a bypass flow adjusting device, wherein the bypass flow adjusting device is disposed in the bypass cooling circuit, and adjusts a flow rate of the refrigerant flowing in the bypass cooling circuit; the opening size control portion When the temperature of the heat dissipating portion is greater than the upper limit of the target temperature range, the bypass flow rate adjusting device is controlled to be in the fully closed state, and when the heat dissipating portion temperature is equal to or lower than the upper limit value of the target temperature range, the side is closed. The flow rate adjusting device is controlled to be in an open state and adjust the flow rate. The refrigerating device of claim 6, wherein the opening size control unit sets the bypass flow rate adjusting device to an open state and adjusts the flow rate, and the temperature of the heat dissipating portion becomes lower than a target temperature range lower limit value. In this case, the bypass flow rate adjusting device is set to the closed state. The freezing device according to any one of claims 1 to 5, wherein the state detecting portion has: an intermediate pressure detecting device that detects an intermediate pressure in the compressor; and a refrigerant temperature detecting device that detects Measure the temperature of the refrigerant flowing into the heat sink of the inverter. The refrigeration device of any one of claims 1 to 5, wherein the state detecting portion has: an intermediate pressure detecting device for detecting an intermediate pressure; and a refrigerant temperature detecting device for detecting the frequency converter The temperature of the refrigerant flowing out of the heat radiating portion. The refrigeration system according to any one of claims 1 to 5, wherein the frequency conversion device and the heat dissipation portion of the inverter are disposed in a casing of the compressor.