Refrigeration equipment

Abstract

To provide a refrigerator that can be manufactured more inexpensively.SOLUTION: A refrigerator includes: a main circuit in which a refrigerant flows; a plurality of compressors; a check valve; a condenser; a receiver; a first expansion valve; an evaporator; an injection flow passage; a solenoid valve disposed on the injection flow passage; a liquid level detection section detecting the amount of the refrigerant stored in the receiver; and a control section. The control section closes the first expansion valve before stopping the compressor, and closes the solenoid valve when the liquid level detection section detects that the amount of a liquid component in the receiver has reached a predetermined upper limit value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to refrigeration devices. [Background technology]

[0002] A typical refrigeration system includes a compressor, a condenser, an expansion valve, a receiver (gas-liquid separator), and an evaporator. The high-temperature, high-pressure gas refrigerant generated by the compressor is first sent to the condenser. In the condenser, heat exchange occurs between the refrigerant and air, transforming the refrigerant into a high-temperature, high-pressure liquid refrigerant. The refrigerant then passes through an expansion valve, lowering its temperature and pressure, transforming into a low-temperature, low-pressure liquid refrigerant. Furthermore, heat exchange occurs with air in the evaporator, transforming the refrigerant into a low-temperature, low-pressure gas refrigerant. During this process, the temperature of the space in which the condenser or evaporator is installed is regulated. In particular, in recent years, in order to improve the output of refrigeration systems, a configuration in which multiple compressors are arranged in series has been adopted (see Patent Document 1 below). In other words, a low-pressure compressor and a high-pressure compressor are arranged in series. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-204454 Summary of the Invention [Problem to be solved by the invention]

[0004] In the past, when shutting down a refrigeration system like the one described above, it was common for the refrigerant to be evenly distributed throughout the piping. Therefore, it was necessary to ensure that the piping and various devices all had a certain level of pressure resistance. As a result, it became necessary to ensure that the pressure resistance of the low-pressure compressor, in particular, was the same as that of the high-pressure compressor, which resulted in increased costs.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a refrigeration device that can be manufactured more inexpensively. [Means for solving the problem]

[0006] In order to solve the above problem, the refrigeration device of the present disclosure includes a main circuit as a circulation flow path through which a refrigerant flows, a plurality of compressors arranged in series on the main circuit, a check valve arranged between the plurality of compressors, a condenser arranged downstream of the plurality of compressors, a receiver arranged downstream of the condenser, a first expansion valve arranged downstream of the receiver, an evaporator arranged downstream of the expansion valve, an injection flow path connecting the receiver and the upstream side of the check valve between the plurality of compressors, a solenoid valve arranged on the injection flow path, a liquid level detection unit that detects the amount of liquid component of the refrigerant stored in the receiver, and a control unit, wherein the control unit closes the first expansion valve before stopping the compressor, and closes the solenoid valve when the liquid level detection unit detects that the amount of the liquid component in the receiver has reached a predetermined upper limit value. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a refrigeration device that can be manufactured at lower cost. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a circuit diagram showing a configuration of a refrigeration device according to a first embodiment of the present disclosure. [Figure 2] 1 is a circuit diagram showing the configuration of a refrigeration device according to a first embodiment of the present disclosure, illustrating a state before operation is stopped. [Figure 3] 1 is a circuit diagram showing the configuration of a refrigeration device according to a first embodiment of the present disclosure, illustrating a state after operation has been stopped. [Figure 4] FIG. 10 is a circuit diagram showing the configuration of a refrigeration device according to a second embodiment of the present disclosure, illustrating a state before operation is stopped. [Figure 5] FIG. 10 is a circuit diagram showing the configuration of a refrigeration device according to a second embodiment of the present disclosure, illustrating a state after operation has been stopped. [Figure 6] FIG. 10 is a circuit diagram showing the configuration of a refrigeration device according to a second embodiment of the present disclosure, illustrating a state in which refrigerant in a receiver is transferred to another receiver during shutdown. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment (Configuration of refrigeration device) A refrigeration device 100 according to a first embodiment of the present disclosure will be described below with reference to Figures 1 to 3. The refrigeration device 100 is a heat pump type device that operates on a refrigeration cycle to exchange heat between a refrigerant and air.

[0010] As shown in FIG. 1, the refrigeration device 100 includes a main circuit 90 formed as a circulation flow path, a first compressor 1 (compressor), a second compressor 2 (compressor), a condenser 4, a first expansion valve 7, a receiver 6, a liquid level detection unit 61, a pressure detection unit 62, a second expansion valve 5, an evaporator 8, an injection flow path 11, a solenoid valve 13, an accumulator 15, a check valve 18, and a control unit 80.

[0011] (Configuration of the first and second compressors) The main circuit 90 is filled with a refrigerant in a liquid or gas state. The first compressor 1 and the second compressor 2 are arranged in series on the main circuit 90. That is, the discharge side of the first compressor 1 faces the suction side of the second compressor 2. The first compressor 1 and the second compressor 2 may be, for example, a scroll compressor, a rotary compressor, or a scroll-rotary compressor. In the following description, the side of the main circuit 90 where the second compressor 2 is located relative to the first compressor 1 may be referred to as the downstream side, and the opposite side may be referred to as the upstream side. A check valve 18 is provided between the first compressor 1 and the second compressor 2. The check valve 18 is configured to allow the refrigerant to flow only from the upstream side to the downstream side.

[0012] (Condenser configuration) A condenser 4 is disposed downstream of the second compressor 2. The condenser 4 is a heat exchanger for exchanging heat between the external air and the refrigerant. A fan (not shown) is provided near the condenser 4, which enables forced heat exchange between the air and the refrigerant. The high-temperature, high-pressure gas refrigerant generated by the second compressor 2 is condensed as it passes through the condenser 4, becoming a high-temperature, high-pressure liquid refrigerant.

[0013] A second expansion valve 5 is provided downstream of the condenser 4. The high-temperature, high-pressure liquid refrigerant supplied from the condenser 4 passes through the second expansion valve 5, whereby its pressure and temperature decrease, turning it into a low-temperature, low-pressure liquid refrigerant.

[0014] (Receiver configuration) A receiver 6 is connected downstream of the second expansion valve 5. The receiver 6 is a container for storing at least a portion of the liquid refrigerant that has passed through the second expansion valve 5. The amount of liquid refrigerant that can be present in the main circuit 90 varies depending on the operating conditions. The receiver 6 is provided to accommodate this variation. A liquid level detector 61 and a pressure detector 62 are attached to the receiver 6. The liquid level detector 61 detects the amount of liquid refrigerant in the receiver 6 and sends it to the control unit 80 as an electrical signal. The pressure detector 62 detects the pressure in the receiver 6 and sends it to the control unit 80 as an electrical signal.

[0015] A first expansion valve 7 is disposed further downstream of the receiver 6. The first expansion valve 7 is provided to further reduce the temperature and pressure of the low-temperature, low-pressure liquid refrigerant that has passed through the receiver 6. The second expansion valve 5 and the first expansion valve 7 are electromagnetic expansion valves that can be switched between open and closed states by an external electrical signal.

[0016] (Evaporator configuration) An evaporator 8 is provided downstream of the first expansion valve 7. The evaporator 8 is a heat exchanger for exchanging heat between the outside air and the refrigerant. A fan (not shown) is provided near the evaporator 8, which enables forced heat exchange between the air and the refrigerant. The low-temperature, low-pressure liquid refrigerant that has passed through the first expansion valve 7 evaporates by exchanging heat with the outside air as it passes through the evaporator 8, and becomes a low-temperature, low-pressure gaseous refrigerant.

[0017] An accumulator 15 is provided downstream of the evaporator 8. The accumulator 15 is a container for storing liquid refrigerant that has not been completely evaporated in the evaporator 8. After the liquid component is removed in the accumulator 15, the gaseous refrigerant is sent again to the first compressor 1 and compressed. The refrigeration device 100 operates by continuously repeating this cycle (refrigeration cycle).

[0018] (Configuration of injection flow path) The injection flow path 11 connects the check valve 18 and the first compressor 1 (i.e., the low-pressure compressor) with the receiver 6. A solenoid valve 13 is provided on the injection flow path 11. The solenoid valve 13 can be switched between an open state and an closed state by an external electric signal.

[0019] (Configuration of control unit) The control unit 80 is provided to switch the open / closed states of the above-mentioned valve devices and the operating states of the first compressor 1 and the second compressor 2 by means of electric signals. Specifically, the control unit 80 can switch the open / closed states of the first expansion valve 7, the second expansion valve 5, and the solenoid valve 13. The control unit 80 can also switch between driving and stopping the first compressor 1 and the second compressor 2.

[0020] (Action and effect) Next, an example of the operation of the refrigeration system 100 will be described. As shown in Fig. 1, when the refrigeration system 100 is in normal operation, the control unit 80 closes the solenoid valve 13. This closes the injection flow path 11, and the refrigerant circulates only through the main circuit 90. While the refrigerant circulates through the main circuit 90, the above-described refrigeration cycle occurs continuously.

[0021] Next, with reference to Figures 2 and 3, an operation when shutting down the refrigeration system 100 will be described. In the refrigeration system 100 described above, it has been common practice to shut down the operation by ensuring that the refrigerant is evenly distributed throughout the piping. This requires that the pressure resistance of the piping and various devices be at least at a certain level. As a result, it has become necessary to ensure that the pressure resistance of the first compressor 1 on the low-pressure side is at the same level as that of the second compressor 2 on the high-pressure side, which has resulted in increased costs.

[0022] Therefore, the refrigeration device 100 according to this embodiment is configured to recover the refrigerant into the receiver 6 by performing the operations described below. As shown in FIG. 2 , first, the control unit 80 closes the first expansion valve 7. This blocks the main circuit 90 downstream of the receiver 6. As a result, the refrigerant in the main circuit 90 and the injection flow path 11 is successively stored in the receiver 6.

[0023] Thereafter, as shown in Fig. 3, when the liquid level detector 61 detects that the receiver 6 is filled with liquid refrigerant (that the amount of refrigerant has reached an upper limit), the controller 80 closes the second expansion valve 5 and the solenoid valve 13. This separates the receiver 6 from the main circuit 90. Next, the controller 80 stops driving the first compressor 1 and the second compressor 2. This causes the refrigeration device 100 to stop.

[0024] As described above, in the refrigeration system 100 according to this embodiment, prior to shutting down the system, the first compressor 1 and the second compressor 2 are operated with the first expansion valve 7 closed, thereby allowing the refrigerant present in the main circuit 90 and each device to be recovered into the receiver 6. Therefore, when the system is shut down, it is difficult for the refrigerant to remain in the main circuit 90 and each device, and it is possible to reduce the pressure resistance of the first compressor 1, particularly on the low-pressure side. As a result, the manufacturing costs and maintenance costs of the refrigeration system 100 can be reduced.

[0025] Furthermore, according to the above configuration, the receiver 6 is separated from the main circuit by closing the second expansion valve 5 in addition to the solenoid valve 13. This allows the refrigerant to be stably contained within the receiver 6.

[0026] The first embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0027] Second Embodiment Next, a refrigeration device 200 according to a second embodiment of the present disclosure will be described with reference to Figures 4 to 6. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0028] As shown in Fig. 4, the number of compressors in this embodiment is different from that in the first embodiment. Specifically, in addition to a first compressor 1 on the lowest pressure side, two second compressors 2a and 2b on the high pressure side are provided on a main circuit 90. One check valve 18 (18a, 18b) is provided upstream of each of the second compressors 2a and 2b.

[0029] Furthermore, in this embodiment, multiple sets (two sets) of each of the receiver 6, first expansion valve 7, injection passage 11, and solenoid valve 13 described in the first embodiment are provided. In the following description, the receiver 6, first expansion valve 7, injection passage 11, and solenoid valve 13 located relatively downstream on the main circuit 90 will be referred to as the downstream receiver 6a, downstream first expansion valve 7a, downstream injection passage 11a, and downstream solenoid valve 13a. In addition, these devices located relatively upstream will be referred to as the upstream receiver 6b, upstream first expansion valve 7b, upstream injection passage 11b, and upstream solenoid valve 13b.

[0030] The downstream injection flow path 11a connects the downstream receiver 6a to the first compressor 1 and the check valve 18a. The upstream injection flow path 11b connects the upstream receiver 6b to the second compressor 2a and the check valve 18b.

[0031] Next, an operation when shutting down the refrigeration apparatus 200 will be described. As shown in Fig. 4, prior to shutting down the refrigeration apparatus 200, the control unit 80 first closes the first downstream expansion valve 7a. As a result, the refrigerant downstream of the first downstream expansion valve 7a on the main circuit 90 is sequentially collected in the downstream receiver 6a.

[0032] Thereafter, when it is detected that the downstream receiver 6a is filled with refrigerant, the control unit 80 closes the first upstream expansion valve 7b and the downstream solenoid valve 13a, as shown in FIG. 5. This separates the downstream receiver 6a from the main circuit 90. Thereafter, any refrigerant still remaining in the main circuit 90 is stored in the upstream receiver 6b. Finally, when it is detected that the upstream receiver 6b is also filled with refrigerant, the control unit 80 closes the second expansion valve 5 and the upstream solenoid valve 13b. This separates the upstream receiver 6b from the main circuit 90. Thereafter, the control unit 80 shuts down the first compressor 1 and the second compressors 2a and 2b. This causes the refrigeration system 200 to stop.

[0033] In this way, the refrigerant is stored in the plurality of receivers 6 sequentially from the downstream receiver 6 to the upstream receiver 6, whereby the refrigerant is recovered from the main circuit 90 and each device.

[0034] Incidentally, when the refrigeration system 200 is stopped as described above, the pressure in the receiver 6 may rise due to the influence of the outside air temperature. For example, consider a case where the pressure detection unit 62 detects that the pressure in the downstream receiver 6a has reached or exceeded a predetermined upper limit pressure. In this case, as shown in FIG. 6, the control unit 80 opens only the downstream solenoid valve 13a and the second expansion valve 5. In this state, the control unit 80 drives the first compressor 1 and the second compressors 2a and 2b. Then, the refrigerant in the downstream receiver 6a flows toward the upstream receiver 6b through the downstream injection flow path 11a and the main circuit 90. The control unit 80 continues this operation until the pressure in the downstream receiver 6a falls below the upper limit pressure.

[0035] As described above, according to the above configuration, in the refrigeration system 200 including multiple receivers 6, the receivers 6 can be filled with refrigerant sequentially from the downstream side to the upstream side. This allows a larger amount of refrigerant to be stored in the multiple receivers 6.

[0036] Furthermore, according to the above configuration, when the pressure in the receiver 6 rises while the refrigeration device 200 is stopped, the refrigerant in the receiver 6 located downstream can be transferred to another receiver 6 located upstream by driving the compressor with the injection flow path 11 connected to the receiver 6 located downstream open. This makes it possible to maintain the pressure in each receiver 6 at or below the upper limit pressure.

[0037] The above describes the embodiments of the present disclosure. Various changes and modifications can be made to the above configurations without departing from the spirit and scope of the present disclosure. For example, in the above embodiments, a two-stage compression refrigeration system 100 including a first compressor 1 and a second compressor 2, and a three-stage compression refrigeration system 200 including a first compressor 1 and second compressors 2a and 2b, have been described. However, the number of compressors is not limited to the above embodiments, and a configuration with four or more stages of compression can be adopted. A specific example of a four-stage compression refrigeration system is a configuration using two scroll rotary compressors. Even with such a configuration, it is possible to achieve the operations described in the second embodiment.

[0038] <Additional Notes> The refrigeration device 100 and the refrigeration device 200 described in each embodiment can be understood, for example, as follows.

[0039] (1) A refrigeration device 100 according to a first aspect includes a main circuit 90 as a circulation flow path through which a refrigerant flows, a plurality of compressors (a first compressor 1 and a second compressor 2) arranged in series on the main circuit 90, a check valve 18 arranged between the plurality of compressors, a condenser 4 arranged downstream of the plurality of compressors, a receiver 6 arranged downstream of the condenser 4, a first expansion valve 7 arranged downstream of the receiver 6, an evaporator 8 arranged downstream of the first expansion valve 7, and a valve between the receiver 6 and the plurality of compressors. The refrigerant expansion valve 6 includes an injection flow path 11 connecting the upstream side of the check valve 18, an electromagnetic valve 13 arranged on the injection flow path 11, a liquid level detection unit 61 that detects the amount of liquid component of the refrigerant stored in the receiver 6, and a control unit 80, wherein the control unit 80 closes the first expansion valve 7 before stopping the compressor, and closes the electromagnetic valve 13 when the liquid level detection unit 61 detects that the amount of the liquid component in the receiver 6 has reached a predetermined upper limit value.

[0040] According to the above configuration, prior to stopping the operation of the refrigeration system 100, the compressor is operated with the first expansion valve 7 closed, so that the refrigerant present in the main circuit 90 and each device can be recovered into the receiver 6. Therefore, when the operation of the refrigeration system 100 is stopped, it becomes difficult for the refrigerant to remain in the main circuit 90 and each device, and it becomes possible to reduce the pressure resistance performance of the compressor, particularly on the low-pressure side.

[0041] (2) The refrigeration device 200 of the second aspect includes multiple sets of the receiver 6, the first expansion valve 7, the injection flow path 11, and the solenoid valve 13 arranged in series on the main circuit 90, and the control unit 80 closes the first expansion valve 7 before stopping the compressor, and controls the solenoid valve 13 to close when the liquid level detection unit 61 detects that the amount of the liquid component in the receiver 6 has reached the upper limit value, sequentially from the first expansion valve 7 and solenoid valve 13 located most downstream among the multiple sets of first expansion valves 7 and solenoid valves 13 to the first expansion valve 7 and solenoid valve 13 located most upstream.

[0042] According to the above configuration, in the refrigeration device 200 including a plurality of receivers 6, the receivers 6 can be filled with the refrigerant sequentially from the downstream side to the upstream side. This allows a larger amount of refrigerant to be stored in the plurality of receivers 6.

[0043] (3) The refrigeration device 200 according to the third aspect further includes a pressure detection unit 62 that detects the pressure within the receiver 6. When the pressure detection unit 62 detects that the pressure within the receiver 6 located relatively upstream among the plurality of receivers 6 has reached or exceeded a predetermined upper limit pressure while the compressor is stopped, the control unit 80 closes the solenoid valve 13 on the injection flow path 11 connected to the receiver 6 located relatively upstream, opens the solenoid valve 13 on the injection flow path 11 connected to the receiver 6 located relatively downstream, and drives the compressor.

[0044] Here, while the refrigeration device 200 is stopped, the pressure inside the receiver 6 may rise due to the influence of the outside air temperature. In such a case, according to the above configuration, by driving the compressor with the injection flow path 11 connected to the receiver 6 located downstream open, the refrigerant inside the receiver 6 located downstream can be transferred to another receiver 6 located upstream. This makes it possible to maintain the pressure inside each receiver 6 at or below the upper limit pressure.

[0045] (4) The refrigeration device 100 according to the fourth aspect further includes a second expansion valve 5 arranged between the condenser 4 and the receiver 6, and the control unit 80 closes the solenoid valve 13 and the second expansion valve 5 when the liquid level detection unit 61 detects that the amount of refrigerant in the receiver 6 has reached a predetermined upper limit value.

[0046] According to the above configuration, the receiver 6 is separated from the main circuit by closing the second expansion valve 5 in addition to the solenoid valve 13. This allows the refrigerant to be stably contained within the receiver 6. [Explanation of symbols]

[0047] 100,200 Refrigeration equipment 90 Main circuit 80 Control Unit 1. First compressor 2,2a,2b Second compressor 4. Condenser 5 Second expansion valve 6 receivers 6a Downstream Receiver 6b Upstream receiver 7 First expansion valve 7a Downstream first expansion valve 7b First upstream expansion valve 8. Evaporator 11 Injection channel 11a Downstream injection channel 11b Upstream injection channel 13 Solenoid valve 13a Downstream solenoid valve 13b Upstream solenoid valve 15 Accumulator 18, 18a, 18b Check valve

Claims

1. a main circuit as a circulation flow path through which the refrigerant flows; a plurality of compressors arranged in series on the main circuit; a check valve disposed between the plurality of compressors; a condenser disposed downstream of the plurality of compressors; a receiver disposed downstream of the condenser; a first expansion valve disposed downstream of the receiver; an evaporator disposed downstream of the first expansion valve; an injection flow path connecting the receiver to an upstream side of the check valve between the plurality of compressors; an electromagnetic valve disposed on the injection flow path; a liquid level detector that detects the amount of the liquid component of the refrigerant stored in the receiver; A control unit; Equipped with The control unit closes the first expansion valve before stopping the compressor, and closes the solenoid valve when the liquid level detection unit detects that the amount of the liquid component in the receiver has reached a predetermined upper limit value.

2. A plurality of the receivers are arranged in series on the main circuit, the first expansion valve, the injection passage, and the solenoid valve are provided corresponding to each of the receivers, The control unit closes the first expansion valve before stopping the compressor, and closes the solenoid valve when the liquid level detection unit detects that the amount of the liquid component in the receiver has reached the upper limit value, sequentially performing control on the first expansion valves and solenoid valves corresponding to each of the multiple receivers, from the first expansion valve and solenoid valve corresponding to the receiver located most downstream among the multiple receivers, to the first expansion valve and solenoid valve corresponding to the receiver located most upstream.

3. Further provided is a pressure detection unit that detects the pressure inside the receiver, 3. The refrigeration apparatus according to claim 2, wherein when the pressure detection unit detects that the pressure in the receiver located relatively upstream among the plurality of receivers has reached or exceeded a predetermined upper limit pressure while the compressor is stopped, the control unit closes the solenoid valve on the injection flow path connected to the receiver located relatively upstream, opens the solenoid valve on the injection flow path connected to the receiver located relatively downstream, and drives the compressor.

4. a second expansion valve disposed between the condenser and the receiver; 4. The refrigeration device according to claim 1, wherein the control unit closes the solenoid valve and the second expansion valve when the liquid level detection unit detects that the amount of refrigerant in the receiver has reached a predetermined upper limit value.

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