Refrigeration equipment and refrigeration unit

Abstract

By incorporating both injection and bypass mechanisms, this refrigeration system provides an appropriate improvement in cooling performance across all load ranges, from low to high loads. [Solution] A refrigeration system according to one embodiment comprises a compressor, a condenser, an evaporator, a main flow path, a branch path, a first control valve, a subcooling heat exchanger, an injection flow path, a check valve, a bypass flow path, a second control valve, a first temperature detection unit, a second temperature detection unit, and a control unit. The control unit includes an operation control unit that appropriately selects either the injection flow path or the bypass flow path based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening of the first control valve.

Description

Technical Field

[0001] Embodiments of the present invention relate to a refrigeration apparatus and a refrigeration unit.

Background Art

[0002] As representative examples of the cooling method of a compressor in a refrigeration apparatus, there are two types: an injection method and a bypass method. In the injection method, for a compressor that generally operates in a low evaporation temperature range and has a tendency to overheat during high compression ratio operation, the liquid refrigerant after the condensation process is made to flow into an internal port of the compressor. On the other hand, in the bypass method, by making the liquid refrigerant flow into the suction gas pipe, which is the low-pressure line of the compressor, the overheating of the compressor is suppressed. In recent years, in addition to these cooling circuits, by incorporating a subcooling heat exchanger, improvement in the cooling capacity and cooling performance of the entire refrigeration cycle has been attempted.

[0003] However, in the injection method, since the refrigerant is returned to the intermediate pressure after the condensation process, the refrigerant temperature only drops to the corresponding pressure level, and a significant temperature drop of the liquid refrigerant cannot be expected. Also, since it is a control that depends on the temperature of the refrigerant discharged from the compressor, there is a possibility that sufficient effects cannot be obtained under conditions where the operation such as low load becomes unstable. In contrast, in the bypass method, since the refrigerant is returned to the suction gas pipe corresponding to the evaporation pressure, a temperature drop of the liquid refrigerant greater than that of the injection method can be expected. However, along with this, since the refrigerant circulation amount in the refrigeration unit decreases, there is a possibility of causing a decrease in the maximum cooling capacity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention was made based on this, and its purpose is to provide a refrigeration device and refrigeration unit that can appropriately improve cooling capacity and cooling performance in all load ranges from low load to high load by incorporating both injection type and bypass type mechanisms. [Means for solving the problem]

[0006] A refrigeration system according to one embodiment includes a compressor, a condenser, an evaporator, a main flow path, a branch path, a first control valve, a subcooling heat exchanger, an injection flow path, a check valve, a bypass flow path, a second control valve, a first temperature detection unit, a second temperature detection unit, and a control unit. The compressor draws in refrigerant from the suction pipe, compresses the drawn-in refrigerant, and discharges it to the discharge pipe. The condenser condenses the refrigerant. The evaporator evaporates the refrigerant. The main flow path includes the suction pipe and the discharge pipe, and the refrigerant circulates through the compressor, the condenser, and the evaporator. The branch path separates a portion of the refrigerant flowing from the condenser to the evaporator from the main flow path downstream of the condenser. The first control valve adjusts the flow rate of the refrigerant flowing through the branch path. The subcooled heat exchanger performs heat exchange between the refrigerant flowing through the branch passage after passing through the first control valve and the refrigerant flowing through the main passage downstream of the condenser. The injection passage injects the refrigerant from the branched flow that has flowed out of the subcooled heat exchanger into the compressor. The check valve prevents backflow of the refrigerant flowing through the injection passage. The bypass passage allows the refrigerant from the branched flow that has flowed out of the subcooled heat exchanger to merge with the main passage downstream of the evaporator. The second control valve adjusts the flow rate of the refrigerant flowing through the bypass passage. The first temperature detection unit detects the first temperature of the refrigerant discharged from the compressor to the discharge pipe between the compressor and the condenser. The second temperature detection unit detects the second temperature of the refrigerant flowing out of the subcooled heat exchanger and through the main passage between the subcooled heat exchanger and the evaporator. The control unit controls the operation of the compressor, the first control valve, the second control valve, the first temperature detection unit, and the second temperature detection unit. The control unit includes an operation control unit that appropriately selects either the injection flow path or the bypass flow path based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening degree of the first control valve.

[0007] A refrigeration unit according to one embodiment comprises at least a compressor and a condenser, and is connected to a load-side unit having an evaporator for evaporating a refrigerant via a main flow path through the compressor, condenser, and evaporator. The compressor draws in refrigerant from an intake pipe, compresses the drawn-in refrigerant, and discharges it through a discharge pipe. The condenser condenses the refrigerant. The refrigeration unit comprises a branch passage, a first control valve, a subcooling heat exchanger, an injection passage, a check valve, a bypass passage, a second control valve, a first temperature detection unit, a second temperature detection unit, and a control unit. The branch passage diverts a portion of the refrigerant from the main flow path downstream of the condenser. The first control valve adjusts the flow rate of the refrigerant flowing through the branch passage. The subcooling heat exchanger performs heat exchange between the refrigerant flowing through the branch passage after passing the first control valve and the refrigerant flowing through the main flow path downstream of the condenser. The injection channel injects the refrigerant from the subcooled heat exchanger into the compressor. The check valve prevents backflow of the refrigerant flowing through the injection channel. The bypass channel allows the refrigerant from the subcooled heat exchanger to merge with the main channel downstream of the evaporator. The second control valve adjusts the flow rate of the refrigerant flowing through the bypass channel. The first temperature detection unit detects the first temperature of the refrigerant discharged from the compressor to the discharge pipe between the compressor and the condenser. The second temperature detection unit detects the second temperature of the refrigerant flowing from the subcooled heat exchanger into the main channel between the subcooled heat exchanger and the evaporator. The control unit controls the operation of the compressor, the first control valve, the second control valve, the first temperature detection unit, and the second temperature detection unit. The control unit includes an operation control unit that appropriately selects either the injection flow path or the bypass flow path based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening degree of the first control valve. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic circuit diagram showing the refrigeration cycle of the refrigeration apparatus according to the embodiment. [Figure 2] This figure shows an example of the configuration of a control switch in the control unit of a refrigeration system according to the embodiment. [Figure 3] This figure shows the control flow of the control unit during operation control of the refrigeration system according to the embodiment. [Figure 4] This is an example of a Mollier diagram (Ph diagram) during normal operation control of a refrigeration system according to the embodiment. [Figure 5] This is an example of a Mollier diagram (Ph diagram) during TD control using the injection flow path of the refrigeration system according to the embodiment. [Figure 6] This is an example of a Mollier diagram (Ph diagram) when TL control is performed using the bypass flow path of the refrigeration system according to the embodiment. [Figure 7] This is a schematic circuit diagram showing the refrigeration cycle of a refrigeration device according to a modified embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic circuit diagram showing the refrigeration cycle of the refrigeration system according to this embodiment. As shown in Figure 1, the refrigeration system 1 includes a refrigeration unit 2 and a load unit 4 connected by a flow path (hereinafter referred to as the main flow path) 8 through which the refrigerant circulates, and a control unit 6 that controls the operation of the refrigeration unit 2 and the load unit 4. Figure 1 shows an example configuration in which there is one refrigeration unit 2 and one load unit 4. The refrigeration system 1 is not limited to the illustrated example and may include multiple refrigeration units 2 or load units 4, or multiple of both.

[0010] The main flow path 8 is composed of multiple connected pipes. These pipes include pipes 21 that constitute the flow path on the refrigeration unit 2 side (hereinafter referred to as refrigeration-side pipes) and pipes 41 that constitute the flow path on the load unit 4 side (hereinafter referred to as load-side pipes). The refrigeration-side pipes 21 and the load-side pipes 41 are connected via fittings, connecting liquid pipes, and connecting gas pipes (all not shown in the figures), for example. The fittings are, for example, packed valves and ball valves. The connecting liquid pipes and connecting gas pipes constitute a part of the main flow path 8.

[0011] The refrigeration unit 2 mainly comprises a compressor 22, a first temperature detection unit 23, a condenser 24, a subcooling heat exchanger 25, and a second temperature detection unit 26.

[0012] The compressor 22 draws in refrigerant from the suction pipe 21a, compresses the refrigerant it draws in, and discharges it through the discharge pipe 21b. The compressor 22 is composed of, for example, a compression mechanism, a housing (sealed container) that houses the compression mechanism and stores refrigerant oil for lubricating the compression mechanism, a rotating shaft, and an electric motor mechanism. The compressor 22 provides the value of the rotational speed during operation to the control unit 6 via wired or wireless connection.

[0013] The suction pipe 21a and discharge pipe 21b are included in the main flow path 8 and each constitute a part of the refrigeration unit side piping 21. The suction pipe 21a is connected, for example, at one end to a suction cup (not shown) and at the other end to the suction port of the compressor 22. The gaseous phase refrigerant, which is recirculated from the load unit 4 and separated into gas and liquid phases by an accumulator (not shown) or suction cup, is drawn into the compressor 22 from the suction pipe 21a. The discharge pipe 21b is connected, for example, at one end to the discharge port of the compressor 22 and at the other end to an oil separator (not shown).

[0014] A first temperature detection unit 23 is located in the discharge pipe 21b. The first temperature detection unit 23 is, for example, a temperature sensor (thermistor) in which a temperature sensing element is placed inside the piping of the discharge pipe 21b to detect a first temperature of the refrigerant. The first temperature of the refrigerant is the temperature of the refrigerant (gas-phase refrigerant) discharged from the compressor 22 to the discharge pipe 21b (hereinafter referred to as the discharge temperature). In the following description, the first temperature detection unit 23 will be referred to as the discharge temperature detection unit 23. As shown in Figure 1, the discharge temperature detection unit 23 detects the discharge temperature of the refrigerant between the compressor 22 and the condenser 24 in the main flow path 8 (refrigeration unit side piping 21). The discharge temperature detection unit 23 provides the detected discharge temperature value to the control unit 6 via wired or wireless connection.

[0015] The refrigerant discharged from the compressor 22 is then guided to the condenser 24 after oil is removed, for example, by an oil separator.

[0016] The condenser 24 performs heat exchange between air and refrigerant, for example, to condense the refrigerant. In this case, the refrigerant condensed in the condenser 24 may be stored in a liquid tank (not shown), and the refrigerant that flows out of the liquid tank may be condensed again in the condenser 24.

[0017] The refrigerant condensed in the condenser 24 is led to the subcooling heat exchanger 25. The subcooling heat exchanger 25 performs heat exchange between the refrigerant flowing through the branch passage 81, which is described later, after passing through the first control valve (branch passage expansion valve) 811 of the branch passage 81, and the refrigerant flowing through the main passage 8 downstream of the condenser 24. The subcooling heat exchanger 25 is equipped with a main flow path 25a and a branch flow path 25b.

[0018] The main flow path 25a is connected at both ends to the refrigerant side piping 21 of the main flow path 8 and constitutes a part of the main flow path 8. The branch flow path 25b is connected at both ends to a branch path 81 described later and constitutes a part of the branch path 81. Thereby, heat exchange is performed between the refrigerant flowing through the main flow path 25a and the refrigerant flowing through the branch flow path 25b. The refrigerant flowing through the main flow path 25a is the refrigerant condensed by the condenser 24 as described above. The refrigerant flowing through the branch flow path 25b is the refrigerant that passes through the first regulating valve (branch path expansion valve) 811 of the branch path 81 described later and flows through the branch path 81. The refrigerant that has undergone heat exchange in the subcooling heat exchanger 25 and flows through the main flow path 8 (refrigerant side piping 21) is supplied to the load unit 4 via, for example, a joint or a connecting liquid pipe.

[0019] Near the outlet of the subcooling heat exchanger 25 in the main flow path 8 (the refrigerant side piping 21 in the illustrated example), a second temperature detection unit 26 is arranged. The second temperature detection unit 26 is, for example, a temperature sensor (thermistor) in which a temperature sensing element is arranged inside the piping of the refrigerant side piping 21 of the main flow path 8 to detect the second temperature of the refrigerant. The second temperature of the refrigerant is the temperature of the refrigerant (liquid-phase refrigerant) that flows out of the subcooling heat exchanger 25 and flows through the refrigerant side piping 21 of the main flow path 8, that is, the temperature of the liquid-phase refrigerant supplied to the load unit 4 (hereinafter referred to as the liquid temperature). In the following description, the second temperature detection unit 26 is referred to as the liquid temperature detection unit 26. As shown in FIG. 1, the liquid temperature detection unit 26 detects the liquid temperature of the refrigerant between the subcooling heat exchanger 25 in the main flow path 8 and the evaporator 42 of the load unit 4 described later. The liquid temperature detection unit 26 provides the detected liquid temperature value to the control unit 6 via wire or wirelessly.

[0020] The load unit 4 mainly includes an evaporator 42 and an expansion valve (hereinafter referred to as the load side expansion valve) 43.

[0021] The evaporator 42 performs heat exchange between, for example, air and the refrigerant and evaporates the refrigerant. At that time, for example, air outside the load unit 4 is sucked in by a blower (not shown) arranged near the evaporator 42 and blown onto the evaporator 42. Thereby, heat exchange is performed between the air blown onto the evaporator 42 and the refrigerant flowing through the evaporator 42.

[0022] The load-side expansion valve 43 is a control valve capable of adjusting the flow rate of refrigerant according to its opening degree. The load-side expansion valve 43 adjusts the flow rate of refrigerant (liquid-phase refrigerant) that is condensed in the condenser 24 and led to the evaporator 42 in the load-side piping 41 of the main flow path 8. The load-side expansion valve 43 has a valve structure in which the amount of refrigerant throttling is adjusted by controlling the valve opening degree between, for example, a lower limit opening degree and an upper limit opening degree, and is configured as a PMV (Pulse Motor Valve) in which the opening degree changes continuously according to the number of drive pulses supplied. The opening degree of the load-side expansion valve 43 is adjusted by the control unit 6, and the current opening degree (actual opening degree) value is provided to the control unit 6 via wired or wireless connection.

[0023] As shown in Figure 1, the refrigeration system 1 of this embodiment has a main flow path 8 and a branch path 81 that branches off from the main flow path 8. The main flow path 8 includes an inlet pipe 21a and a discharge pipe 21b, and is a flow path through which the refrigerant circulates via a compressor 22, a condenser 24, and an evaporator 42. The branch path 81 is a flow path that separates a portion of the refrigerant flowing from the condenser 24 to the evaporator 42 from the main flow path 8 downstream of the condenser 24.

[0024] In the illustrated example, the branch channel 81 branches off from the main channel 8 downstream of the condenser 24, more specifically downstream of the subcooled heat exchanger 25. The branch channel 81, which branches off from the main channel 8, is connected to both ends of the diversion channel 25b of the subcooled heat exchanger 25 and passes through the diversion channel 25b. In other words, the branch channel 81 includes the diversion channel 25b in part.

[0025] A control valve (the first control valve, hereinafter referred to as the branch expansion valve) 811 is located in the branch passage 81 to adjust the flow rate of the refrigerant flowing through the branch passage 81. The branch expansion valve 811 is located in the branch passage 81 between the branching point from the main flow path 8 (in other words, the starting point of the branch passage 81) B1 and the branched flow path 25b of the subcooling heat exchanger 25, and adjusts the flow rate of the refrigerant guided to the branched flow path 25b. The branch expansion valve 811 is included as a component of the refrigeration unit 2.

[0026] The branch expansion valve 811 has a valve structure in which the amount of refrigerant throttling is adjusted by controlling the valve opening between, for example, a lower limit opening and an upper limit opening, and is configured as a PMV (Pulse Motor Valve) in which the opening changes continuously according to the number of drive pulses supplied. The branch expansion valve 811 is adjusted by the control unit 6 and the current opening value (actual opening) is provided to the control unit 6 via wired or wireless connection.

[0027] When the branch expansion valve 811 opens, a portion of the refrigerant flowing out of the main flow path 25a of the subcooled heat exchanger 25 is diverted, and this diverted refrigerant flows through the branch passage 81. In this state, increasing or decreasing the opening degree of the branch expansion valve 811 increases or decreases the flow rate of refrigerant flowing through the branch passage 81, that is, the flow rate of refrigerant guided to the diverted flow path 25b of the subcooled heat exchanger 25. Conversely, when the branch expansion valve 811 closes, the refrigerant flowing out of the main flow path 25a of the subcooled heat exchanger 25 is not diverted, and the flow of refrigerant in the branch passage 81, or more precisely, the flow of refrigerant in the diverted flow path 25b of the subcooled heat exchanger 25, stops.

[0028] Furthermore, the refrigeration system 1 of this embodiment has two branching channels, an injection channel 82 and a bypass channel 83, which further branch off from the branching channel 81. The injection channel 82 is one of the channels into which the branching channel 81 branches downstream of the diversion channel 25b of the supercooling heat exchanger 25. The bypass channel 83 is the other channel into which the branching channel 81 branches downstream of the diversion channel 25b. In the illustrated example, the branching channel 81 branches into the injection channel 82 and the bypass channel 83 at branching point B2. Branching point B2 is the starting point of the injection channel 82 and the bypass channel 83, respectively.

[0029] The injection channel 82 injects the refrigerant flowing out of the subcooled heat exchanger 25, specifically the refrigerant flowing out of the sub-flow channel 25b, into the compressor 22. The injection channel 82 is connected, for example, to the injection pipe 21c of the compressor 22. The injection pipe 21c is included in the main channel 8 and constitutes part of the refrigeration unit side piping 21. For example, one end of the injection pipe 21c is connected to the injection channel 82, and the other end is connected to the inlet of the compressor 22.

[0030] A control valve 821 is positioned in the injection passage 82 to control the flow of refrigerant in the injection passage 82. The control valve 821 is a component of the refrigeration unit 2 and, in this embodiment, is a check valve (hereinafter referred to as check valve 821) that suppresses the backflow of refrigerant flowing through the injection passage 82. The check valve 821 restricts the flow of refrigerant in the injection passage 82 to the direction from the subcooling heat exchanger 25 toward the compressor 22 and suppresses the flow of refrigerant in the opposite direction (backflow).

[0031] The bypass channel 83 allows the refrigerant flowing out of the subcooled heat exchanger 25, specifically the refrigerant flowing out of the sub-flow channel 25b, to merge with the main channel 8 downstream of the evaporator 42. In the illustrated example, the bypass channel 83 branches off from the branching channel 81 and merges with the main channel 8 at junction B3 in the refrigeration-side piping 21. Junction B3 is the endpoint of the bypass channel 83. As a result, the refrigerant flowing out of the sub-flow channel 25b is mixed with the refrigerant evaporated in the evaporator 42 (either gaseous or gas-liquid mixed refrigerant).

[0032] A control valve (a second control valve, hereinafter referred to as the bypass control valve) 831 is located in the bypass channel 83 to adjust the flow rate of the refrigerant flowing through the bypass channel 83. The bypass control valve 831 is included as a component of the refrigeration unit 2 and is configured as a solenoid valve that can be electrically switched between an open state and a closed state. The bypass control valve 831 is controlled to open and close by the control unit 6 and provides the control unit 6 with a status value indicating whether it is in an open or closed state via wired or wireless connection.

[0033] As the branch expansion valve 811 opens and the bypass control valve 831 opens, the refrigerant flowing out from the branch side flow path 25b of the subcooling heat exchanger 25 flows into the bypass flow path 83 instead of the injection flow path 82. This is because the refrigerant pressure in the bypass flow path 83 is lower than the refrigerant pressure in the injection flow path 82, so the refrigerant flowing out from the branch side flow path 25b is drawn into the bypass flow path 83 instead of the injection flow path 82.

[0034] In other words, when both the branch expansion valve 811 and the bypass control valve 831 are open, the refrigerant flowing out from the branch side passage 25b flows into the bypass passage 83 due to the pressure difference between the injection passage 82 and the bypass passage 83. In this state, increasing or decreasing the opening degree of the branch expansion valve 811 increases or decreases the flow rate of refrigerant flowing through the bypass passage 83. At that time, the check valve 821 of the injection passage 82 prevents the refrigerant from flowing back through the injection passage 82 and into the bypass passage 83.

[0035] In response to this, when the bypass control valve 831 closes, the refrigerant that has flowed out from the diversion channel 25b of the subcooled heat exchanger 25 does not flow into the bypass channel 83, and the flow of refrigerant in the bypass channel 83 stops. On the other hand, when the branch expansion valve 811 opens while the bypass control valve 831 is closed, the refrigerant that has flowed out from the diversion channel 25b of the subcooled heat exchanger 25 flows into the injection channel 82.

[0036] In this way, when the branch expansion valve 811 opens, a portion of the refrigerant that has flowed out from the main flow path 25a of the subcooled heat exchanger 25 is diverted from the refrigeration unit side piping 21 in the main flow path 8 and flows into the branch flow path 25b of the subcooled heat exchanger 25. Then, when the bypass control valve 831 opens and closes while the branch expansion valve 811 is open, the refrigerant that has flowed out from the branch flow path 25b of the subcooled heat exchanger 25 flows into either the injection flow path 82 or the bypass flow path 83.

[0037] In other words, when the bypass control valve 831 closes while the branch expansion valve 811 is open, the refrigerant flowing out from the branch side passage 25b flows through the injection passage 82. Conversely, when the bypass control valve 831 opens while the branch expansion valve 811 is open, the refrigerant flowing out from the branch side passage 25b flows through the bypass passage 83. Therefore, by opening and closing the bypass control valve 831 while the branch expansion valve 811 is open, the flow path of the refrigerant flowing out from the branch side passage 25b can be switched to either the injection passage 82 or the bypass passage 83.

[0038] As described above, the control unit 6 controls the operation of the refrigeration unit 2 and the load unit 4. The control unit 6 includes a CPU, memory, storage device (non-volatile memory), input / output circuits, timers, etc., and performs predetermined calculation processing. For example, the control unit 6 reads various data using the input / output circuits, performs calculation processing with the CPU using a program read from the storage device into memory, and controls the operation of the compressor 22, branch expansion valve (first control valve) 811, bypass control valve (second control valve) 831, discharge temperature detection unit (first temperature detection unit) 23, liquid temperature detection unit (second temperature detection unit) 26, load-side expansion valve 43, etc., based on the processing results.

[0039] The control unit 6 has an operation control unit 61 that performs such operation control. The operation control unit 61 is configured as a program (operation control program) that causes the CPU to execute predetermined calculation processes to control the operation of each of the operation control targets described above, such as starting (starting operation) and stopping, and the driving mode. The operation control program is stored, for example, in the storage device (non-volatile memory) of the control unit 6 and read into the memory of the control unit 6 when executed. The operation control unit 61 transmits and receives control signals and data signals to and from the operation control targets via wired or wireless means. In other words, the operation control unit 61 and the operation control targets are electrically connected by wired or wireless means.

[0040] The operation control unit 61 appropriately selects either the injection flow path 82 or the bypass flow path 83 based on the discharge temperature (first temperature) of the refrigerant detected by the discharge temperature detection unit (first temperature detection unit) 23 and the liquid temperature (second temperature) of the refrigerant detected by the liquid temperature detection unit (second temperature detection unit) 26, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening degree of the branch expansion valve (first control valve) 811. Further details will be described later.

[0041] Furthermore, the control unit 6 is equipped with a control switch 62 for setting whether or not to use the injection channel 82 and the bypass channel 83. In this embodiment, the control switch 62 has a first switch 621 for setting whether or not to use the injection channel 82 and a second switch 622 for setting whether or not to use the bypass channel 83. Thus, in this embodiment, as an example, whether or not to use the injection channel 82 and whether or not to use the bypass channel 83 are both selected and set (switched) in advance by an operator or the like using switches 621 and 622, respectively. However, these settings may also be set in software by a program or the like.

[0042] Figure 2 shows an example of the configuration of the control switches 62 in the control unit 6. In the example shown in Figure 2, four control switches 62 are provided to switch the operating mode of the refrigeration unit 1. Two of these switches are designated as the first switch 621 and the second switch 622. The first switch 621 corresponds to the selection setting of the injection type operating mode using the injection flow path 82. The second switch 622 corresponds to the selection setting of the bypass type operating mode using the bypass flow path 83. These switches 621 and 622 are shown as slide type in one example, but they may also be push-button type or dial type, and the switching method is not limited to the illustrated example.

[0043] In Figure 2, in the example shown as control method 1, the first switch 621 is set to ON, allowing the injection flow path 82 to be used, and the second switch 622 is set to OFF, preventing the bypass flow path 83 from being used (unavailable). This operating mode (operating control method) is a state in which the refrigeration system 1 is operated and controlled in the capacity-prioritizing mode (injection method) described later.

[0044] In Figure 2, in the example shown as control method 2, the first switch 621 is set to OFF, so that the injection passage 82 is not used (unusable), and the second switch 622 is set to ON, so that the bypass passage 83 can be used. This operating mode (operating control method) is a state in which the refrigeration system 1 is operated and controlled in the pressure loss improvement mode (bypass method) described later.

[0045] In Figure 2, in the example shown as control method 3, the first switch 621 is set to ON, enabling the use of the injection channel 82, and the second switch 622 is set to ON, enabling the use of the bypass channel 83. This operating mode (operating control method) is a state in which the operation control of the refrigeration system 1 is selected in the full-load performance mode (combination of injection method and bypass method), which will be described later.

[0046] As will be explained in more detail later, even in full-load performance mode, the injection channel 82 and the bypass channel 83 are never used simultaneously. During operation of the refrigeration system 1, the channels are switched to use one or the other as appropriate. However, during operation of the refrigeration system 1 in full-load performance mode, there are times when neither the injection channel 82 nor the bypass channel 83 is used, as in the normal operation control described later. In other words, full-load performance mode means that either the injection channel 82 or the bypass channel 83 can be selectively used.

[0047] The control unit appropriately selects either the injection flow path 82 or the bypass flow path 83 according to the settings of the first switch 621 and the second switch 622, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening of the first control valve. Thus, when the use of the injection channel 82 is selected (set) by the first switch 621, the injection channel 82 can be used in the refrigeration system 1. In this case, the operation control unit 61 uses the injection channel 82 according to predetermined conditions described later and controls the flow rate of the refrigerant in the injection channel 82. On the other hand, when the use of the injection channel 82 is not selected (set) by the first switch 621, the injection channel 82 cannot be used in the refrigeration system 1.

[0048] In other words, if the use of the injection flow path 82 is selected (set) by the first switch 621, the operation control unit 61 closes the bypass control valve (second control valve) 831. Then, with the bypass control valve 831 closed, the operation control unit 61 opens the branch expansion valve (first control valve) 811 and adjusts the opening degree of the branch expansion valve 811 according to the refrigerant discharge temperature (first temperature) detected by the discharge temperature detection unit (first temperature detection unit) 23 and the refrigerant liquid temperature (second temperature) detected by the liquid temperature detection unit (second temperature detection unit) 26. Further details will be described later.

[0049] On the other hand, if the use of the bypass channel 83 is selected (set) by the second switch 622, the bypass channel 83 can be used in the refrigeration unit 1. In this case, the operation control unit 61 uses the bypass channel 83 according to predetermined conditions described later and controls the flow rate of the refrigerant in the bypass channel 83. Conversely, if the use of the bypass channel 83 is not selected (set) by the second switch 622, the bypass channel 83 cannot be used in the refrigeration unit 1.

[0050] In other words, if the use of the bypass flow path 83 is selected (set) by the second switch 622, the operation control unit 61 opens the branch expansion valve (first control valve) 811 and the bypass control valve (second control valve) 831, and adjusts the opening degree of the branch expansion valve 811 according to the refrigerant discharge temperature (first temperature) detected by the discharge temperature detection unit (first temperature detection unit) 23 and the refrigerant liquid temperature (second temperature) detected by the liquid temperature detection unit (second temperature detection unit) 26. Further details will be described later.

[0051] In the refrigeration system 1 having the above configuration, the operation control of the refrigeration system 1 performed by the control unit 6, specifically the control for appropriately switching between the injection flow path 82 and the bypass flow path 83 during operation of the refrigeration system 1 (hereinafter referred to as operation mode switching control), will be explained according to the control flow of the control unit 6. Figure 3 is a diagram showing the control flow of the control unit 6 during operation mode switching control.

[0052] In the operating mode switching control shown in Figure 3, the control switch 62 of the control unit 6 is configured such that the first switch 621 selects (sets) to use the injection flow path 82, and the second switch 622 selects (sets) to use the bypass flow path 83. Therefore, in the illustrated example, the refrigeration system 1 is configured to allow switching between the injection flow path 82 and the bypass flow path 83 as appropriate.

[0053] In controlling the operation mode, the control unit 6 starts the operation of the refrigeration system 1 (S101). Specifically, the operation control unit 61 starts the compressor 22 and circulates the refrigerant through the main passage 8. At this time, the operation control unit 61 closes the branch passage expansion valve 811 and the bypass control valve 831, and opens the load-side expansion valve 43. Therefore, when the refrigeration system 1 starts operation, the refrigerant flowing through the main passage 8 is not diverted to the branch passage 81 and does not flow into either the injection passage 82 or the bypass passage 83.

[0054] When the operation of the refrigeration system 1 is started and the circulation of the refrigerant in the main flow path 8 begins, the operation control unit 61 starts detecting the discharge temperature (TD) and liquid temperature (TL) of the refrigerant (S102). At this time, the discharge temperature detection unit 23, which is controlled by the operation control unit 61, starts detecting the discharge temperature of the refrigerant. Also, the liquid temperature detection unit 26, which is controlled by the operation control unit 61, starts detecting the liquid temperature of the refrigerant. The discharge temperature detection unit 23 and the liquid temperature detection unit 26 provide the detected values ​​to the operation control unit 61. In subsequent steps, when comparing the discharge temperature (TD) and liquid temperature (TL) of the refrigerant with predetermined threshold values, the operation control unit 61 acquires these detected values ​​and stores each acquired detected value in, for example, the memory of the control unit 6.

[0055] When the detection of the refrigerant discharge temperature (TD) and liquid temperature (TL) begins, the operation control unit 61 determines whether the discharge temperature (TD) is equal to or greater than a first discharge temperature threshold (S103). The first discharge temperature threshold is a threshold used to determine whether to perform normal operation control, which will be described later, without using either the injection flow path 82 or the bypass flow path 83. In this embodiment, as an example, the first discharge temperature threshold is set to 50°C. The first discharge temperature threshold is stored, for example, in the memory of the control unit 6 (non-volatile memory) and read from the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 acquires the discharge temperature (TD) when the above determination is made and compares the acquired discharge temperature with the first discharge temperature.

[0056] If the discharge temperature (TD) is determined to be less than the first discharge temperature threshold (TD < 50°C) (No in S103), the operation control unit 61 performs normal operation control (S104). Normal operation control is one mode of operation control for the refrigeration system 1, which operates the refrigeration system 1 without using either the injection flow path 82 or the bypass flow path 83. During normal operation control, the refrigerant flowing through the main flow path 8 is not diverted to the branch path 81 and does not flow into either the injection flow path 82 or the bypass flow path 83. Therefore, during normal operation control, the refrigerant circulates only through the main flow path 8.

[0057] In contrast, if it is determined that the discharge temperature (TD) is equal to or greater than the first discharge temperature threshold (TD ≥ 50°C) (Yes in S103), the operation control unit 61 determines whether or not the liquid temperature (TL) is equal to or greater than the first liquid temperature threshold (S105). The first liquid temperature threshold is a threshold (the third threshold in the claim) used to determine whether or not to start using the bypass flow path 83. In this embodiment, as an example, the first liquid temperature threshold is set to 18°C. The first liquid temperature threshold is stored, for example, in the memory of the control unit 6 (non-volatile memory) and read out into the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 obtains the liquid temperature (TL) when the above determination is made and compares the obtained liquid temperature with the first discharge temperature.

[0058] If the liquid temperature (TL) is determined to be less than the first liquid temperature threshold (TL < 18°C) (No in S105), the operation control unit 61 determines whether the discharge temperature (TD) is equal to or greater than the second discharge temperature threshold (S106). The second discharge temperature threshold is a threshold (the first threshold in the claim) used to determine whether or not to start using the injection flow path 82. In this embodiment, as an example, the second discharge temperature threshold is set to 80°C. The second discharge temperature threshold is stored, for example, in the memory of the control unit 6 (non-volatile memory) and read out into the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 obtains the discharge temperature (TD) when the above determination is made and compares the obtained discharge temperature with the second discharge temperature.

[0059] If it is determined that the discharge temperature (TD) is below the second discharge temperature threshold (TD < 80°C) (No in S106), the operation control unit 61 performs normal operation control (S104).

[0060] In contrast, if the discharge temperature (TD) is determined to be equal to or greater than the second discharge temperature threshold (TD ≥ 80°C) (Yes in S106), the operation control unit 61 sets the branch expansion valve 811 to the first opening (S107). As a result, a portion of the refrigerant flowing through the main passage 8 is diverted to the branch passage 81 and flows into the injection passage 82. That is, injection control (operation control in capacity-prioritizing mode) is started in the refrigeration system 1. The first opening is the fixed opening of the branch expansion valve 811 at the start of injection control. Therefore, at the time when such injection control is started, the opening of the branch expansion valve 811 is fixed to the first opening. In this case, since the bypass control valve 831 is closed, the refrigerant diverted to the branch passage 81 does not flow into the bypass passage 83. The first opening degree is predetermined, for example, by a combination of the model of the refrigeration device 1 and the type of refrigerant used, and is stored in the memory (non-volatile memory) of the control unit 6. When the opening degree of the branch expansion valve 811 is set, the first opening degree is read from the memory of the control unit 6.

[0061] Next, the operation control unit 61 determines whether the discharge temperature (TD) is equal to or greater than the third discharge temperature threshold (S108). The third discharge temperature threshold is a threshold used to determine whether or not to use the injection flow path 82 and start the TD control described later (the second threshold in the claim). In this embodiment, as an example, the third discharge temperature threshold is set to 85°C. The third discharge temperature threshold is stored, for example, in the memory (non-volatile memory) of the control unit 6 and read out into the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 obtains the discharge temperature (TD) when the above determination is made and compares the obtained discharge temperature with the third discharge temperature.

[0062] If the discharge temperature (TD) is determined to be less than the third discharge temperature threshold (TD < 85°C) (No in S108), the operation control unit 61 sets the branch expansion valve 811 to the first opening (S107). In this case, if the opening of the branch expansion valve 811 is already set to the first opening, the operation control unit 61 maintains the opening of the branch expansion valve 811 without changing it.

[0063] In contrast, if it is determined that the discharge temperature (TD) is equal to or greater than the third discharge temperature threshold (TD ≥ 85°C) (Yes in S108), the operation control unit 61 performs TD control (S109). TD control is the opening degree control of the branch expansion valve 811 according to the discharge temperature (TD) of the refrigerant when the injection flow path 82 is in use. Therefore, in TD control, the flow rate of the refrigerant in the injection flow path 82 is controlled according to the discharge temperature (TD).

[0064] In this embodiment, the following control is performed as TD control. When performing TD control, the operation control unit 61 stores the discharge temperature (TD) at the time TD control is started. The operation control unit 61 stores this discharge temperature (TD) value in the memory of the control unit 6, for example. Next, at predetermined intervals (hereinafter referred to as the TD control cycle), the operation control unit 61 acquires the current discharge temperature (hereinafter referred to as TDn) and calculates the temperature change amount (ΔTDn) from the most recent discharge temperature (hereinafter referred to as TDn-1) (ΔTDn = TDn - TDn-1).

[0065] The operation control unit 61 then corrects the opening degree of the branch expansion valve 811 according to the calculated temperature change (ΔTDn) and the control target value for the discharge temperature (hereinafter referred to as TDC1). The control target value (TDC1) is a target value that is set in advance according to the model of the refrigeration system 1, for example, when controlling the discharge temperature (TD) of the refrigerant. The operation control unit 61 adds a correction value (hereinafter referred to as ΔPLSTDn) to the current opening degree of the branch expansion valve 811 (hereinafter referred to as PLS) to calculate the corrected opening degree of the branch expansion valve 811 (hereinafter referred to as PLS') (PLS' = PLS + ΔPLSTDn). In other words, the operation control unit 61 adjusts the opening degree of the branch expansion valve 811 by increasing or decreasing it based on the correction value (ΔPLSTDn).

[0066] The correction value (ΔPLSTDn) is uniquely set in advance based on, for example, the relationship between the difference between the discharge temperature (TD) and the control target value (TDC1) and the temperature change amount of the discharge temperature (ΔTDn). The set values ​​of the correction value (ΔPLSTDn) based on these correspondences are stored in the memory (non-volatile memory) of the control unit 6, for example, in a table, and are read from the memory of the control unit 6 when correcting the opening degree of the branch expansion valve 811.

[0067] The TD control period corresponds to the interval (correction interval) at which the opening degree of the branch expansion valve 811 is corrected in TD control. For example, the period is relatively short from immediately after the start of TD control until a predetermined number of corrections, and relatively long for subsequent corrections. As an example, the TD control period is set to 5 to 10 seconds from immediately after the start of TD control until the fourth correction, and then to 20 seconds for the fifth correction and beyond.

[0068] In addition to performing such TD control, the operation control unit 61 determines whether the discharge temperature (TD) is below a fourth discharge temperature threshold (S110). The fourth discharge temperature threshold is a threshold used to determine whether or not to terminate the TD control. That is, the fourth discharge temperature threshold corresponds to the control target value (TDC1) of the discharge temperature (TD) in the TD control (the first target value in the claim). In this embodiment, as an example, the fourth discharge temperature threshold is set to 70°C. The fourth discharge temperature threshold is stored, for example, in the memory (non-volatile memory) of the control unit 6 and read from the memory when the above determination is made. In this case, the operation control unit 61 acquires the discharge temperature (TD) when the above determination is made and compares the acquired discharge temperature with the fourth discharge temperature.

[0069] If the operation control unit 61 determines that the discharge temperature (TD) exceeds the fourth discharge temperature threshold (TD > 70°C) (No in S110), the operation control unit 61 continues to perform TD control (S109). In other words, TD control is repeated as long as the discharge temperature (TD) exceeds the fourth discharge temperature threshold.

[0070] In contrast, if the operation control unit 61 determines that the discharge temperature (TD) is below the fourth discharge temperature threshold (TD ≤ 70°C) (Yes in S110), the operation control unit 61 closes the branch expansion valve 811 (S111). This terminates the TD control.

[0071] In S105, if it is determined that the liquid temperature (TL) is equal to or greater than the first liquid temperature threshold (TL ≥ 18°C) (Yes in S105), the operation control unit 61 sets the branch expansion valve 811 to a second opening (S112). The second opening is the fixed opening of the branch expansion valve 811 at the start of the TL control described later. That is, at the time when such TL control is started, the opening of the branch expansion valve 811 is fixed to the second opening. As a result, a portion of the refrigerant flowing through the main passage 8 is diverted to the branch passage 81 and flows into the injection passage 82. In this case, since the bypass control valve 831 is closed, the refrigerant diverted to the branch passage 81 does not flow into the bypass passage 83. The second opening is set in advance, for example, based on a combination of the model of the refrigeration system 1 and the type of refrigerant used, and is stored in the memory (non-volatile memory) of the control unit 6. It is then read from the memory of the control unit 6 when the opening of the branch expansion valve 811 is set. The second opening degree may be the same as or different from the first opening degree.

[0072] Next, the operation control unit 61 determines whether the liquid temperature (TL) is equal to or greater than the second liquid temperature threshold (TL0) and whether the discharge temperature (TD) is equal to or greater than the fifth discharge temperature threshold (TD0) (S113). The second liquid temperature threshold (the fifth threshold in the claim) and the fifth discharge temperature threshold (the fourth threshold in the claim) are thresholds used to determine whether to use the bypass flow path 83 and start the TL control described later. In this embodiment, as an example, the second liquid temperature threshold (TL0) is set to 24°C and the fifth discharge temperature threshold (TD0) is set to 90°C. The second liquid temperature threshold and the fifth discharge temperature threshold are stored, for example, in the storage device (non-volatile memory) of the control unit 6 and read out into the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 acquires the liquid temperature (TL) and discharge temperature (TD) when the above determination is made, compares the acquired liquid temperature with the second liquid temperature threshold, and compares the acquired discharge temperature with the fifth discharge temperature.

[0073] If the liquid temperature (TL) is determined to be below the second liquid temperature threshold (TL < 24°C), or the discharge temperature (TD) is below the fifth discharge temperature threshold (TD < 90°C) (No in S113), the operation control unit 61 sets the branch expansion valve 811 to the second opening (S112). In this case, if the opening of the branch expansion valve 811 is already set to the second opening, the operation control unit 61 maintains the opening of the branch expansion valve 811 without changing it.

[0074] In contrast, if it is determined that the liquid temperature (TL) is equal to or greater than the second liquid temperature threshold (TL0) (TL≧24℃) and the discharge temperature (TD) is equal to or greater than the fifth discharge temperature threshold (TD0) (TD≧90℃) (Yes in S113), the operation control unit 61 opens the bypass control valve 831 (S114). As a result, a portion of the refrigerant flowing through the main passage 8 is diverted to the branch passage 81 and flows into the bypass passage 83. In this case, the check valve 821 of the injection passage 82 functions, so the refrigerant diverted to the branch passage 81 does not flow into the injection passage 82.

[0075] When the bypass control valve 831 is opened, the operation control unit 61 performs TL control (S115). TL control is the opening degree control of the branch expansion valve 811 according to the refrigerant discharge temperature (TD) when the bypass flow path 83 is in use. Therefore, in TL control, the flow rate of the refrigerant in the bypass flow path 83 is controlled according to the discharge temperature (TD).

[0076] In this embodiment, the following control is performed as TL control. When performing TL control, the operation control unit 61 stores the discharge temperature (TD) at the time TL control is started. The operation control unit 61 stores this discharge temperature (TD) value in, for example, the memory of the control unit 6. Next, at predetermined intervals (hereinafter referred to as the TL control cycle), the operation control unit 61 acquires the current discharge temperature (hereinafter referred to as TDm) and calculates the temperature change amount (ΔTDm) from the most recent discharge temperature (hereinafter referred to as TDm-1) (ΔTDm = TDm - TDm-1).

[0077] The operation control unit 61 then corrects the opening degree of the branch expansion valve 811 according to the calculated temperature change (ΔTDm) and the control target value (TDC2) for the discharge temperature. The control target value (TDC2) is a target value that is set in advance according to the model of the refrigeration system 1, for example, when controlling the discharge temperature (TD) of the refrigerant. The operation control unit 61 adds a correction value (hereinafter referred to as ΔPLSTDm) to the current opening degree (PLS) of the branch expansion valve 811 to calculate the corrected opening degree (PLS') of the branch expansion valve 811 (PLS' = PLS + ΔPLSTDm). In other words, the operation control unit 61 adjusts the opening degree of the branch expansion valve 811 by increasing or decreasing it based on the correction value (ΔPLSTDm).

[0078] The correction value (ΔPLSTDm) is uniquely predetermined based on, for example, the relationship between the difference between the discharge temperature (TD) and the control target value (TDC2) and the temperature change amount of the discharge temperature (ΔTDm). The setting values ​​of the correction value (ΔPLSTDm) based on these correspondences are stored in the memory (non-volatile memory) of the control unit 6, for example, by creating a table, and are read from the memory of the control unit 6 when correcting the opening degree of the branch expansion valve 811. The setting value of the correction value (ΔPLSTDm) may or may not match the setting value of the correction value (ΔPLSTDn) during TD control as described above.

[0079] The TL control period corresponds to the interval (correction interval) at which the opening degree of the branch expansion valve 811 is corrected during TL control. For example, the period is relatively short from immediately after the start of TL control until a predetermined number of corrections, and relatively long for subsequent corrections. As an example, the TL control period is set to 5 to 10 seconds from immediately after the start of TL control until the fourth correction, and then to 20 seconds for the fifth correction and beyond.

[0080] In addition to performing this TL control, the operation control unit 61 determines whether the discharge temperature (TD) is below the sixth discharge temperature threshold (S116). The sixth discharge temperature threshold is a threshold used to determine whether or not to terminate the TL control. That is, the sixth discharge temperature threshold corresponds to the control target value (TDC2) of the discharge temperature (TD) in the TL control (the second target value in the claim). In this embodiment, as an example, the sixth discharge temperature threshold is set to 40°C. Therefore, the fourth discharge temperature threshold (control target value (TDC1)) is greater than the sixth discharge temperature threshold (control target value (TDC2)). The sixth discharge temperature threshold is stored, for example, in the memory of the control unit 6 (non-volatile memory) and read into the memory of the control unit 6 when the above determination is made. In this case, the operation control unit 61 obtains the discharge temperature (TD) when the above determination is made and compares the obtained discharge temperature with the sixth discharge temperature.

[0081] If the operation control unit 61 determines that the discharge temperature (TD) exceeds the sixth discharge temperature threshold (TD > 40°C) (No in S116), the operation control unit 61 continues to perform TL control (S115). In other words, TL control is repeated as long as the discharge temperature (TD) exceeds the sixth discharge temperature threshold.

[0082] In contrast, if the operation control unit 61 determines that the discharge temperature (TD) is below the sixth discharge temperature threshold (TD ≤ 40°C) (Yes in S116), the operation control unit 61 closes the branch expansion valve 811 and the bypass control valve 831 (S117). This terminates the TL control.

[0083] When TL control is completed, the operation control unit 61 determines the conditions for stopping the operation of the refrigeration unit 1 (S118). Similarly, when normal operation control is performed in S104, or when TD control is completed in S111, the operation control unit 61 determines the conditions for stopping the operation of the refrigeration unit 1 (S118). The conditions for stopping the operation are the conditions for determining whether or not to stop the operation of the refrigeration unit 1. The conditions for stopping the operation are determined, for example, depending on whether or not the operation control unit 61 has received a signal indicating that the operation of the refrigeration unit 1 has been stopped. The signal indicating that the operation has been stopped is transmitted, for example, when a user selects to stop the operation from the control panel of the control unit 6, the operation panel of the refrigeration unit 2 or load unit 4, or a remote control.

[0084] If the conditions for stopping operation are met (Yes in S118), the operation control unit 61 stops the operation of the refrigeration unit 1 (S119). If the stopped refrigeration unit 1 subsequently starts operation again, a new operation mode switching control is performed separately.

[0085] In contrast, if the operating stop condition is not met (No in S118), the operation control unit 61 acquires the refrigerant discharge temperature (TD) and liquid temperature (TL), respectively, and selectively executes steps S103 to S117 according to the refrigerant discharge temperature (TD) and liquid temperature (TL). In other words, a series of operating mode switching controls are repeated while the refrigeration unit 1 is in operation. When the operation of the refrigeration unit 1 is stopped, the series of operating mode switching controls also ends.

[0086] Thus, according to this embodiment, the refrigeration device 1 is equipped with both an injection channel 82 and a bypass channel 83. In other words, the refrigeration device 1 is equipped with both an injection system and a bypass system as a mechanism for cooling the compressor 22.

[0087] As a result, the refrigeration unit 1 can appropriately select and execute one of the following control methods depending on the refrigerant discharge temperature (TD) and liquid temperature (TL): normal operation control without using either the injection flow path 82 or the bypass flow path 83; TD control using the injection flow path 82; or TL control using the bypass flow path 83. In other words, the cooling capacity and cooling performance of the refrigeration unit 1 can be appropriately improved in the load range from low load to high load. To put it another way, the cooling capacity and cooling performance of the refrigeration unit 2 can be appropriately improved in the load range from low load to high load.

[0088] The effects of TD control using the injection channel 82 and TL control using the bypass channel 83 in the refrigeration unit 1 will be explained in comparison to normal operation control. Figures 4 to 6 are Mollier diagrams (Ph diagrams) of the refrigeration unit 1, with Figure 4 showing an example of normal operation control, Figure 5 showing an example of TD control using the injection channel 82, and Figure 6 showing an example of TL control using the bypass channel 83. Note that P1 to P8 shown in Figures 4 to 6 correspond to the positions of P1 to P8 in the refrigeration cycle shown by white circles in Figure 1.

[0089] By using the injection channel 82, as shown in Figures 4 and 5, the injection method injects the refrigerant at an intermediate pressure after the condensation process into the compressor 22, so the efficiency of the subcooling heat exchanger 25 is not high. In this case, the degree of subcooling (SC shown in Figure 5) does not increase significantly, but the amount of refrigerant circulating in the refrigeration cycle (main channel 8 of the refrigeration device 1) can be kept almost constant. At that time, when the discharge temperature (TD) of the refrigerant rises above a predetermined temperature (for example, 85°C), the flow rate of the refrigerant in the injection channel 82 can be adjusted according to the discharge temperature (TD). This makes it possible to appropriately suppress the compressor 22 from becoming overheated when the discharge temperature (TD) rises and the refrigeration device 1 is under medium to high load.

[0090] In contrast, by using the bypass channel 83, as shown in Figures 4 and 6, the refrigerant that has flowed through the bypass channel 83 is merged into the suction pipe of the compressor 22, i.e., the low-pressure piping, thereby increasing the efficiency of the subcooling heat exchanger 25 and increasing the degree of subcooling (SC shown in Figure 6). On the other hand, since the refrigerant that has flowed through the bypass channel 83 is returned to the refrigeration unit 2, the amount of refrigerant circulated to the load unit 4 decreases. At that time, when the liquid temperature (TL) of the refrigerant rises above a predetermined temperature (for example, 24°C) and the discharge temperature (TD) rises above a predetermined temperature (for example, 90°C), the flow rate of the refrigerant in the bypass channel 83 can be adjusted according to the discharge temperature (TD). This allows TL control to be performed according to the degree of subcooling, reducing the amount of refrigerant circulated to the load unit 4, improving the pressure loss in the evaporator 42, and ensuring an appropriate degree of subcooling.

[0091] Therefore, according to this embodiment, the cooling capacity and cooling performance of the refrigeration device 1 and the refrigeration unit 2 can be appropriately improved in all load ranges from low load to high load.

[0092] Furthermore, the control switches 62 (first switch 621, second switch 622) of the control unit 6 allow for appropriate setting of whether or not to use the injection flow path 82 and the bypass flow path 83. For example, if the first switch 621 is set to use the injection flow path 82, the cooling capacity of the refrigeration system 1 is prioritized, and the performance of the refrigeration system 1 during operation under medium to high load conditions can be improved. In other words, the refrigeration system 1 is operated in a capacity-prioritizing mode (injection method) that prioritizes the cooling capacity of the refrigeration system 1.

[0093] For example, if the second switch 622 is set to use the bypass flow path 83, the pressure loss of the evaporator 42 in the refrigeration system 1 can be improved when the load changes from low to medium, prioritizing the avoidance of pressure loss in the evaporator 42 of the refrigeration system 1. In other words, the refrigeration system 1 is operated in a pressure loss improvement mode (bypass method) that prioritizes improving the pressure loss of the evaporator 42 of the refrigeration system 1.

[0094] Therefore, by setting the first switch 621 to use the injection channel 82 and the second switch 622 to use the bypass channel 83, it is possible to appropriately improve the performance of the refrigeration system 1 during operation under medium to high load conditions, and to improve the pressure loss of the evaporator 42 of the refrigeration system 1 under low to medium load conditions. In other words, it is possible to improve the performance of the refrigeration system 1 in all load ranges: low, medium, and high load. Furthermore, since the optimal control method for the refrigeration system 1 can be selected by the control switch 62, the versatility and ease of installation of the refrigeration system 1 can be improved.

[0095] In this case, the control switch 62 can be used to select and set a full-load performance mode (a combined method for both types) that allows the refrigeration system 1 to be operated by selectively switching between a performance-oriented mode (injection method) and a pressure loss improvement mode (bypass method) as appropriate. This allows the refrigeration system 1 to be operated and controlled in full-load performance mode.

[0096] In this embodiment, as an example, the operation control of the refrigeration system 1 shown in Figure 3 is described in the case where, as shown in Figure 2, the first switch 621 is selected (set) to use the injection channel 82 in a capacity-prioritizing mode (injection method), and the second switch 622 is selected (set) to use the bypass channel 83 in a pressure loss improvement mode (bypass method). That is, when the refrigeration system 1 switches between using either the injection channel 82 or the bypass channel 83 as appropriate, that is, during the operation of the refrigeration system 1, The case in which the refrigeration system 1 is operated and controlled by appropriately switching between the injection method and the bypass method was described.

[0097] Alternatively, if, for example, the use of the injection channel 82 is not selected (set) by the first switch 621, the injection channel 82 will not be used, and TD control will not be performed. In this case, steps S106 to S111 in Figure 3 are omitted in the operation control of the refrigeration unit 1.

[0098] Furthermore, if, for example, the use of the bypass channel 83 is not selected (set) by the second switch 622, the bypass channel 83 will not be used, and TL control will not be performed. In this case, steps S112 to S117 in Figure 3 are omitted in the operation control of the refrigeration unit 1.

[0099] Therefore, if neither the injection channel 82 nor the bypass channel 83 is selected (set), neither the injection channel 82 nor the bypass channel 83 will be used, and steps S106 to S117 in Figure 3 will be omitted in the operation mode switching control of the refrigeration unit 1. In this case, only normal operation control will be performed in the refrigeration unit 1.

[0100] As described above, according to this embodiment, by appropriately switching between normal operation control, TD control, and TL control, the cooling performance of the refrigeration system 1 can be appropriately improved in all load ranges from low load to high load. In addition to this embodiment, an embodiment in which a capillary tube is placed in the injection passage 82 (hereinafter referred to as a modified example) may be used, from the viewpoint of further preventing backflow from the injection passage 82 to the bypass passage 83 and preventing chattering in the check valve 821.

[0101] In this modified example, the components other than the capillary tube are the same as those in the refrigeration device 1 and the refrigeration unit 2 constituting the refrigeration device 1 in the embodiment shown in Figure 1. Therefore, in the following description, the components other than the capillary tube in the modified refrigeration device and the refrigeration unit constituting the refrigeration device will be described using the same reference numerals as those used in the refrigeration device 1 and the refrigeration unit 2, with reference to Figure 1 as appropriate, and their descriptions will be omitted or simplified.

[0102] Figure 7 is a schematic circuit diagram showing the refrigeration cycle of the refrigeration device 100 according to this modified example. As shown in Figure 7, the refrigeration device 100, like the refrigeration device 1 shown in Figure 1, includes a refrigeration unit 200 and a load unit 4 connected by a main flow path 8 through which the refrigerant circulates, and a control unit 6 that controls the operation of the refrigeration unit 200 and the load unit 4.

[0103] In this modified example, a capillary tube 822 is positioned in the injection channel 82. The capillary tube 822 is a component that reduces the pressure of the refrigerant flowing through the injection channel 82. In the injection channel 82, the capillary tube 822 is positioned between the check valve 821 and the injection pipe 21c of the compressor 22. In other words, the capillary tube 822 is positioned downstream of the check valve 821 and upstream of the injection pipe 21c of the compressor 22 in the direction of refrigerant flow in the injection channel 82. Both ends of the capillary tube 822 are connected to the injection channel 82, and it constitutes a part of the injection channel 82. As a result, the capillary tube 822 reduces the pressure of the refrigerant flowing out of the check valve 821 in the injection channel 82 to a level lower than before it flowed into the check valve 821.

[0104] Similar to the embodiment described above shown in Figure 1, in this modified example, a check valve 821 is provided in the injection passage 82, and the bypass control valve 831 of the bypass passage 83 is opened to prevent backflow of refrigerant from the injection passage 82 to the bypass passage 83 when the injection is stopped, that is, when the branch expansion valve 811 is closed.

[0105] Furthermore, in this modified example, by arranging the capillary tube 822 in the injection channel 82, the refrigerant flowing out of the check valve 821 is depressurized by the capillary tube 822 downstream of the check valve 821. Therefore, a differential pressure can be secured between the refrigerant flowing into the check valve 821 and the refrigerant flowing out of the check valve 821. This prevents chattering of the check valve 821 due to pressure pulsations caused by insufficient differential pressure.

[0106] Although embodiments of the present invention and variations thereof have been described above, these are presented as examples only and are not intended to limit the scope of the invention. Such novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0107] 1,100...Refrigeration unit, 2,200...Refrigeration unit, 4...Load unit, 6...Control unit, 8...Main flow path, 61...Operation control unit, 62...Control switch, 81...Branch path, 82...Injection flow path, 83...Bypass flow path, 21...Refrigerator side piping, 21a...Suction pipe, 21b...Discharge pipe, 21c...Injection pipe, 22...Compressor, 23...First temperature detection unit (discharge temperature detection unit), 24...Condenser, 25...Subcooling heat exchanger, 25a...Main flow path, 25b...Diversion flow path, 26...Second temperature detection unit (liquid temperature detection unit), 41...Load side piping , 42... Evaporator, 43... Expansion valve (load-side expansion valve), 61... Operation control unit, 62... Control switch, 621... First switch, 622... Second switch, 811... First regulating valve (branch expansion valve), 821... Control valve (check valve), 822... Capillary tube, 831... Second regulating valve (bypass regulating valve), B1... Branching point from the main flow path in the branch path (starting point of the branch path), B2... Branching point of the branch path (starting points of the injection flow path and the bypass flow path), B3... Confluence point of the bypass flow path in the main flow path (ending point of the bypass flow path).

Claims

1. A compressor that draws in refrigerant from an inlet pipe, compresses the drawn-in refrigerant, and discharges it through a discharge pipe, A condenser for condensing the aforementioned refrigerant, An evaporator for evaporating the refrigerant, A main flow path, including the suction pipe and the discharge pipe, through which the refrigerant circulates via the compressor, the condenser, and the evaporator, A branching channel that separates a portion of the refrigerant flowing from the condenser to the evaporator from the main flow channel downstream of the condenser, A first adjustment valve for adjusting the flow rate of the refrigerant flowing through the branch passage, A subcooling heat exchanger that performs heat exchange between the refrigerant flowing through the branch path after passing through the first control valve and the refrigerant flowing through the main path downstream of the condenser, An injection channel for injecting the refrigerant on the diversion side that has flowed out of the supercooled heat exchanger into the compressor, A check valve that prevents the backflow of the refrigerant flowing through the injection channel, A bypass channel is provided to merge the refrigerant on the diverted side that has flowed out of the subcooled heat exchanger into the main channel downstream of the evaporator, A second control valve for adjusting the flow rate of the refrigerant flowing through the bypass channel, A first temperature detection unit detects the first temperature of the refrigerant discharged from the compressor to the discharge pipe between the compressor and the condenser, A second temperature detection unit detects the second temperature of the refrigerant flowing out of the subcooled heat exchanger and through the main flow path between the subcooled heat exchanger and the evaporator, The system comprises the compressor, the first control valve, the second control valve, the first temperature detection unit, and a control unit that controls the operation of the second temperature detection unit. The control unit includes an operation control unit that appropriately selects either the injection path or the bypass path based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected path by increasing or decreasing the opening of the first control valve. Refrigeration equipment.

2. The aforementioned operation control unit, When both the first and second control valves are closed, if the first temperature of the refrigerant detected by the first temperature detection unit exceeds a first threshold, the opening of the first control valve is set to a first opening. If the first temperature exceeds a second threshold, the opening of the first control valve is adjusted from the first opening until the first temperature falls below a preset first target value. With both the first and second control valves closed, if the second temperature of the refrigerant detected by the second temperature detection unit exceeds the third threshold, the opening of the first control valve is set to the second opening. If the first temperature exceeds the fourth threshold and the second temperature exceeds the fifth threshold, the second control valve is opened, and the opening of the first control valve is adjusted from the second opening until the first temperature falls below a preset second target value. The refrigeration apparatus according to claim 1.

3. The operation control unit calculates the amount of change in the first temperature and adjusts the opening of the first control valve by increasing or decreasing it based on a correction value determined by the difference between the first temperature and the first target value or the second target value, and the calculated amount of change. The refrigeration apparatus according to claim 2.

4. The first target value is greater than the second target value. The refrigeration apparatus according to claim 2.

5. The control unit includes a control switch having a first switch for setting whether or not to use the injection channel and a second switch for setting whether or not to use the bypass channel. The operation control unit appropriately selects one of the flow paths set to be used by the control switch based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected flow path by increasing or decreasing the opening of the first control valve. A refrigeration apparatus according to any one of claims 1 to 4.

6. A refrigeration unit is connected to a load-side unit having a main flow path through which the refrigerant circulates via the compressor, condenser, and evaporator, comprising at least a compressor that draws in refrigerant from an intake pipe, compresses the drawn-in refrigerant, and discharges it to a discharge pipe, and a condenser that condenses the refrigerant, and an evaporator that evaporates the refrigerant, The aforementioned refrigeration unit is A branching path is provided downstream of the condenser to divert a portion of the refrigerant from the main flow path, A first adjustment valve for adjusting the flow rate of the refrigerant flowing through the branch passage, A subcooling heat exchanger that performs heat exchange between the refrigerant flowing through the branch path after passing through the first control valve and the refrigerant flowing through the main path downstream of the condenser, An injection channel for injecting the refrigerant on the diversion side that has flowed out of the supercooled heat exchanger into the compressor, A check valve that prevents the backflow of the refrigerant flowing through the injection channel, A bypass channel is provided to merge the refrigerant on the diverted side that has flowed out of the subcooled heat exchanger into the main channel downstream of the evaporator, A second control valve for adjusting the flow rate of the refrigerant flowing through the bypass channel, A first temperature detection unit detects the first temperature of the refrigerant discharged from the compressor to the discharge pipe between the compressor and the condenser, A second temperature detection unit detects the second temperature of the refrigerant flowing out of the subcooled heat exchanger and through the main flow path between the subcooled heat exchanger and the evaporator, The system comprises the compressor, the first control valve, the second control valve, the first temperature detection unit, and a control unit that controls the operation of the second temperature detection unit. The control unit includes an operation control unit that appropriately selects either the injection path or the bypass path based on the first temperature of the refrigerant detected by the first temperature detection unit and the second temperature of the refrigerant detected by the second temperature detection unit, and adjusts the flow rate of the refrigerant in the selected path by increasing or decreasing the opening of the first control valve. Refrigeration unit.

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