Heat source unit and refrigeration cycle device

Abstract

Provided is a heat source unit that is connected by piping to a load unit and constitutes a refrigerant cycle, wherein the heat source unit comprises: a compressor having an injection port; a condenser for condensing refrigerant by heat exchange; a liquid receiver for storing the refrigerant that has passed through the condenser; an intermediate injection flow passage having intermediate injection piping and an intermediate injection control valve for controlling passage of the refrigerant in the intermediate injection piping, the intermediate injection flow passage guiding some of the refrigerant flowing from the condenser to the liquid receiver to the injection port; an intake injection flow passage having intake injection piping and an intake injection control valve for controlling passage of the refrigerant in the intake injection piping, the intake injection flow passage guiding some of the refrigerant flowing from the liquid receiver toward an evaporator to the intake side of the compressor; and a connection flow passage having connection piping for connecting the intermediate injection piping and the intake injection piping, and a connection control valve for controlling passage of the refrigerant in the connection piping.

Description

Heat source unit and refrigeration cycle device

[0001] This technology relates to a heat source unit and a refrigeration cycle device, and in particular to an injection method for injecting a refrigerant into a compressor.

[0002] In refrigeration cycle systems such as air conditioners, a portion of the refrigerant flowing from the condenser to the evaporator is injected into the compressor to merge with the refrigerant at an intermediate pressure, or the refrigerant is injected into the suction side of the compressor to merge with the refrigerant at a low pressure. Depending on the type of injection used, a refrigerant flow path other than the main refrigerant circuit is formed.

[0003] A refrigeration system having both an intermediate injection flow path and a suction injection flow path has been disclosed (see, for example, Patent Document 1). This refrigeration system can switch between using the intermediate injection flow path to merge with the refrigerant being compressed in the compressor, or using the suction injection flow path to merge with the low-pressure refrigerant being drawn into the compressor in the suction flow path. Therefore, when intermediate injection would degrade operating efficiency under certain operating conditions, the refrigeration system can use suction injection to lower the compressor discharge temperature while minimizing the degradation of operating efficiency.

[0004] JP 2014-01917 A

[0005] The refrigeration system of Patent Document 1 switches from the intermediate injection flow path to the suction injection flow path when it is necessary to lower the compressor discharge temperature. In the refrigeration system of Patent Document 1, the intermediate injection flow path and the suction injection flow path are independent flow paths. However, there is a demand for linking the intermediate injection flow path and the suction injection flow path to improve operating efficiency while controlling condensation capacity or responding to abnormalities.

[0006] Therefore, in order to solve the above problems, the heat source unit and refrigeration cycle device according to this disclosure aim to improve the operating efficiency.

[0007] The heat source unit according to this disclosure is a heat source unit that is connected to a load unit having a load-side expansion valve and an evaporator through piping and that constitutes a refrigerant circuit for circulating refrigerant, and that includes a compressor having an injection port for introducing refrigerant and that draws in, compresses, and discharges the refrigerant, a condenser that condenses the refrigerant through heat exchange, a receiver that stores the refrigerant that has passed through the condenser, an intermediate injection pipe and an intermediate injection control valve that controls the passage of refrigerant through the intermediate injection pipe, and in the refrigerant circuit, an intermediate injection flow path that directs a portion of the refrigerant flowing from the condenser to the receiver to the injection port of the compressor, and an suction injection control valve that controls the passage of refrigerant through the suction injection pipe and the suction injection flow path, and in the refrigerant circuit, an suction injection flow path that directs a portion of the refrigerant flowing from the receiver toward the evaporator to the suction side of the compressor, and a connecting flow path that connects the intermediate injection pipe and the suction injection pipe and has a connection control valve that controls the passage of refrigerant through the connecting pipe.

[0008] A refrigeration cycle device according to the present disclosure includes the above heat source unit and a load unit having a load-side expansion valve and an evaporator.

[0009] According to the heat source unit and refrigeration cycle device disclosed herein, it is possible to improve the operating efficiency.

[0010] 1 is a diagram illustrating a configuration of a refrigeration device 1 according to a first embodiment. FIG. 2 is a diagram illustrating a control relationship in the refrigeration device 1 according to the first embodiment. FIG. 3 is a diagram illustrating a refrigerant flow under operating conditions of the refrigeration device 1 according to the first embodiment. FIG. 4 is a diagram illustrating the state of each solenoid valve under operating conditions of the refrigeration device 1. FIG. 5 is a diagram illustrating a processing flow of a control device 800 according to the first embodiment. FIG. 6 is a diagram illustrating a refrigerant flow when an intermediate injection blockage is detected in the refrigeration device 1 according to the second embodiment. FIG. 7 is a diagram illustrating the state of each solenoid valve under operating conditions of the refrigeration device 1. FIG. 8 is a diagram illustrating a refrigerant flow during liquid backflow prevention in the refrigeration device 1 according to the third embodiment. FIG. 9 is a diagram illustrating the state of each solenoid valve during liquid backflow prevention in the refrigeration device 1. FIG. 10 is a diagram illustrating a refrigerant flow during high-pressure abnormality prevention in the refrigeration device 1 according to the fourth embodiment. FIG. 11 is a diagram illustrating the state of each solenoid valve during high-pressure abnormality prevention in the refrigeration device 1. FIG. 11 is a diagram illustrating a configuration of a refrigeration device 1 according to a fifth embodiment. FIG. 12 is a diagram illustrating the refrigerant flow during operation of the refrigeration device 1 according to the fifth embodiment. FIG. 13 is a diagram illustrating the state of each solenoid valve during operation of the refrigeration device 1. FIG. 14 is a diagram illustrating the state of each solenoid valve during operation of the refrigeration device 1.

[0011] A heat source unit and a refrigeration cycle apparatus according to embodiments will be described below with reference to the drawings. In the following drawings, components with the same reference numerals are identical or equivalent and will be common throughout the following embodiments. The dimensional relationships between components in the drawings may differ from those in reality. The configurations of components shown throughout the specification are merely illustrative and are not limited to those described in the specification. In particular, the combinations of components are not limited to those in each embodiment; components described in other embodiments may be applied to other embodiments. Furthermore, the levels of pressure and temperature are not determined in relation to absolute values, but are determined relatively in terms of the state, operation, etc. of the device. When multiple similar devices are distinguished by subscripts, the subscripts may be omitted if there is no need to distinguish or identify them.

[0012] Embodiment 1. Fig. 1 is a diagram showing the configuration of a refrigeration system 1 according to embodiment 1. The refrigeration system 1 shown in Fig. 1 is a refrigeration system that performs a vapor compression refrigeration cycle operation. Here, the refrigeration system 1 will be described as an example of a refrigeration system. Here, Fig. 1 functionally shows the connection relationships and arrangement of each device in the refrigeration system, and does not necessarily show the physical spatial arrangement.

[0013] The refrigeration device 1 cools a cooling load of a space to be cooled, such as a room, a warehouse, a showcase, or a refrigerator. The refrigeration device 1 in the first embodiment has, for example, one heat source unit 100 and one load unit 600, as shown in FIG. 1 . Here, the number of heat source units 100 and the number of load units 600 are not particularly limited. For example, there may be two or more heat source units 100. There may also be two or more load units 600.

[0014] The refrigeration device 1 has a refrigerant circuit configured by connecting the heat source unit 100 and the load unit 600 via a liquid refrigerant extension pipe 710 and a gas refrigerant extension pipe 720. The refrigerant circuit in the first embodiment has flow paths through which the refrigerant flows that branch off from the refrigerant circuit, as will be described later, but here the main circuit through which the refrigerant circulates will be described as the refrigerant circuit.

[0015] In the refrigeration system 1 of the first embodiment, the refrigerant filled in the refrigerant circuit is carbon dioxide (CO ２ ) However, the present invention is not limited to this, and other refrigerants may be used in cases where it is difficult to ensure the degree of subcooling. In the following description, a refrigeration system 1 in which the refrigerant exchanges heat with air will be described. However, the present invention is not limited to this. For example, the present invention may be a refrigeration system 1 in which the refrigerant exchanges heat with a fluid such as water, refrigerant, or brine.

[0016] The load unit 600 is a unit installed, for example, in a room that is a space to be cooled. The load unit 600 has a load expansion valve 610, a load solenoid valve 620, a load heat exchanger 630, and a load fan 640. The load expansion valve 610, the load heat exchanger 630, and the load solenoid valve 620 are connected by piping and are devices that constitute the main parts of the refrigerant circuit.

[0017] The load-side expansion valve 610 adjusts the pressure and flow rate of the refrigerant passing through the load-side heat exchanger 630. The load-side expansion valve 610 has a throttling device, such as an electronic expansion valve or a temperature-sensitive expansion valve. Here, the refrigeration system 1 of the first embodiment will be described assuming that the load unit 600 has the load-side expansion valve 610, but the heat source unit 100 may have the load-side expansion valve 610.

[0018] The load-side heat exchanger 630 in the first embodiment functions as an evaporator that evaporates the refrigerant by heat exchange with the indoor air. The load-side heat exchanger 630 is, for example, a fin-and-tube heat exchanger configured with a plurality of heat transfer tubes and a plurality of fins.

[0019] The load side solenoid valve 620 is a valve that controls the opening and closing of the passage of refrigerant in the load unit 600 based on instructions from a control device 800 described later. When the load side solenoid valve 620 is closed, no refrigerant flows into the refrigerant circuit of the load unit 600.

[0020] The load-side fan 640 is a blower that sends air to the load-side heat exchanger 630 and then sends the cooled air to the space to be cooled. The load-side fan 640 is disposed near the load-side heat exchanger 630. The load-side fan 640 is configured, for example, as a centrifugal fan or a multi-blade fan. The load-side fan 640 is driven by a motor (not shown). The load-side fan 640 can adjust the amount of air sent to the load-side heat exchanger 630 by controlling the rotation speed of the motor.

[0021] The heat source unit 100 is a unit that supplies heat to the load unit 600. The heat source unit 100 has a compressor 110, an oil separator 111, a heat source side heat exchanger 120, an auxiliary heat exchanger 130, a heat source side expansion valve 140, a receiver 150, a subcooling heat exchanger 160, an accumulator 170, a check valve 171, and a heat source side fan 180. The compressor 110, the oil separator 111, the heat source side heat exchanger 120, the auxiliary heat exchanger 130, the heat source side expansion valve 140, the receiver 150, the subcooling heat exchanger 160, the accumulator 170, and the check valve 171 are connected by piping and are devices that constitute the main parts of the refrigerant circuit. Here, the heat source unit 100 in embodiment 1 will be described as a single unit, but for example, the devices within the heat source unit 100 may be divided into two or more units.

[0022] The compressor 110 compresses and discharges the drawn refrigerant. The compressor 110 is, for example, a scroll compressor, a reciprocating compressor, or a vane compressor. The refrigeration system 1 in the first embodiment includes, for example, an inverter device (not shown) that can arbitrarily change the drive frequency of the power supplied to the compressor 110. Therefore, the compressor 110 can change the drive frequency based on instructions from a control device 800 (described later), thereby changing the rotation speed of a motor (not shown) included in the compressor 110 and changing the drive capacity. The compressor 110 in the first embodiment also includes an injection port 110A. Therefore, the heat source unit 100 can perform intermediate injection, in which the refrigerant flows into the intermediate pressure section of the compressor 110.

[0023] The oil separator 111 separates refrigeration oil discharged together with gaseous refrigerant (hereinafter referred to as gas refrigerant) from the compressor 110. The refrigeration oil separated in the oil separator 111 is returned to the compressor 110, for example, through a capillary tube (not shown) connected to the compressor 110. The oil separator 111 can return most of the refrigeration oil discharged from the compressor 110 to the compressor 110. Here, the oil separator 111 may be integrated with the compressor 110.

[0024] The heat source-side heat exchanger 120 in the first embodiment functions as a condenser that condenses the refrigerant by heat exchange with the outdoor air. The heat source-side heat exchanger 120 is, for example, a fin-and-tube heat exchanger configured with a plurality of heat transfer tubes and a plurality of fins.

[0025] The heat source-side fan 180 is a blower that blows air to the heat source-side heat exchanger 120. The heat source-side fan 180 is disposed near the heat source-side heat exchanger 120. The heat source-side fan 180 is configured, for example, as a centrifugal fan or a multi-blade fan. The heat source-side fan 180 can adjust the amount of air blown by, for example, changing the rotation speed of a motor (not shown) based on instructions from a control device 800, which will be described later.

[0026] The auxiliary heat exchanger 130 in the first embodiment is a heat exchanger that complements the condensing capacity of the heat source-side heat exchanger 120 and condenses the refrigerant passing through the refrigerant circuit. The auxiliary heat exchanger 130 is configured, for example, as an inter-refrigerant heat exchanger such as a double-pipe or plate heat exchanger having two refrigerant flow paths. The auxiliary heat exchanger 130 exchanges heat between the refrigerant flowing through the refrigerant circuit from the heat source-side heat exchanger 120 toward the receiver 150 and the refrigerant flowing through the intermediate injection flow path 200. The refrigerant flowing through the refrigerant circuit releases heat and condenses, while the refrigerant flowing through the intermediate injection flow path 200 absorbs heat.

[0027] The heat source-side expansion valve 140 decompresses the refrigerant that has passed through the heat source-side heat exchanger 120 and the auxiliary heat exchanger 130. The heat source-side expansion valve 140 has a throttling device such as an electronic expansion valve whose opening is controlled by the control device 800 (described later). For example, when the refrigerant is carbon dioxide, the outdoor air temperature may become higher than the supercritical temperature of the refrigerant. In this case, the compressor 110 is driven with a high discharge pressure, and the pressure on the high-pressure side of the refrigerant circuit increases. The heat source-side expansion valve 140 decompresses the refrigerant to meet the pressure resistance setting specified for the load unit 600.

[0028] The receiver 150 is a container that stores excess liquid refrigerant (hereinafter referred to as liquid refrigerant) that occurs in the refrigerant circuit due to, for example, the magnitude of the load in the load unit 600, the condensing temperature of the refrigerant, the outdoor air temperature, and the capacity of the compressor 110. The receiver 150 also stores refrigerant when the refrigeration system 1 performs a pump-down operation. The pump-down operation is an operation that recovers the refrigerant in the refrigerant circuit and confines it in high-pressure side equipment and piping in the refrigerant circuit, such as the heat source unit 100.

[0029] The subcooling heat exchanger 160 is a heat exchanger that subcools the refrigerant passing through the refrigerant circuit. The subcooling heat exchanger 160 is configured as a refrigerant-to-refrigerant heat exchanger, such as a double-pipe or plate heat exchanger, that has two refrigerant flow paths. The subcooling heat exchanger 160 exchanges heat between the refrigerant flowing through the refrigerant circuit from the receiver 150 toward the liquid refrigerant extension pipe 710 and the refrigerant flowing through the suction injection flow path 300. The refrigerant flowing through the refrigerant circuit releases heat and becomes subcooled, while the refrigerant flowing through the suction injection flow path 300 absorbs heat.

[0030] The accumulator 170 is installed on the suction side of the compressor 110. The accumulator 170 passes gas refrigerant through the suction side of the compressor 110 and accumulates liquid refrigerant. The check valve 171 is installed on the refrigerant inlet side of the accumulator 170. The check valve 171 is a valve that prevents refrigerant from flowing back from the accumulator 170 toward the gas refrigerant extension pipe 720.

[0031] Furthermore, the heat source unit 100 in the first embodiment has an intermediate injection flow path 200, a suction injection flow path 300, a receiver flow path 400, and a connection flow path 500 as refrigerant flow paths other than the main refrigerant circuit.

[0032] The intermediate injection flow path 200 includes an intermediate injection branch pipe 210 and an intermediate injection pipe 220 as flow path pipes. The intermediate injection flow path 200 also includes a discharge temperature control valve 230 and an intermediate injection solenoid valve 240 as intermediate injection control valves. The intermediate injection branch pipe 210 branches a portion of the refrigerant, which flows from one flow path of the auxiliary heat exchanger 130 and into the receiver 150 in the refrigerant circuit, from the refrigerant circuit and passes through the other flow path of the auxiliary heat exchanger 130. The intermediate injection pipe 220 also branches the refrigerant that has passed through the auxiliary heat exchanger 130 or the refrigerant flowing through a connecting flow path 500 (described later), into an intermediate pressure section of the compressor 110. The discharge temperature control valve 230 is a throttle valve that adjusts and controls the amount and pressure of refrigerant flowing through the intermediate injection branch pipe 210 based on instructions from a control device 800 (described later). The intermediate injection solenoid valve 240 is an on-off valve that controls whether or not the refrigerant is allowed to pass through the intermediate injection branch pipe 210 based on an instruction from a control device 800, which will be described later.

[0033] The suction injection flow path 300 is provided with a suction injection branch pipe 310 and a suction injection pipe 320 as flow path pipes. The suction injection flow path 300 is also provided with a subcooling adjustment valve 330 and a suction injection solenoid valve 340 as intermediate injection control valves. The suction injection flow path 300 is also provided with an inlet-side solenoid valve 350. The suction injection branch pipe 310 is a pipe that branches a portion of the refrigerant that flows from one flow path of the subcooling heat exchanger 160 in the refrigerant circuit and flows into the liquid refrigerant extension pipe 710, and passes the other flow path of the subcooling heat exchanger 160. The suction injection pipe 320 is a pipe that allows the refrigerant that has passed through the auxiliary heat exchanger 130 to flow into the suction side of the compressor 110, located on the inlet side of the accumulator 170 and upstream of the check valve 171. Therefore, in this example, one end of the suction injection pipe 320 is connected to the inlet pipe of the accumulator 170. However, the connection position is not limited thereto. The subcooling adjustment valve 330 is a valve that functions as a throttle device to adjust the amount and pressure of refrigerant flowing through the suction injection branch pipe 310 based on instructions from the control device 800 (described later). This allows the degree of subcooling of the refrigerant passing through the subcooling heat exchanger 160 to be adjusted. The suction injection solenoid valve 340 is a control valve that controls whether refrigerant is allowed to pass through the suction injection branch pipe 310 by opening and closing based on instructions from the control device 800 (described later). The inlet solenoid valve 350, which is a suction side control valve that controls the passage of refrigerant flowing to the suction side of the compressor 110, is an opening and closing valve that controls whether refrigerant passing through the suction injection pipe 320 and into the suction side pipe of the compressor 110 is allowed to pass based on instructions from the control device 800 (described later). In particular, inlet-side solenoid valve 350 is a valve that controls, by opening and closing, whether to pass refrigerant flowing on the inlet side of accumulator 170 and the upstream side of check valve 171. Here, instead of inlet-side solenoid valve 350, a throttle device that adjusts the flow rate may be used as the inlet-side control valve, which is an opening and closing valve.

[0034] The receiver flow path 400 has a gas vent pipe 410 and a gas solenoid valve 420. One end of the gas vent pipe 410 is connected to the receiver 150, and the other end is connected to the suction injection pipe 320. The receiver flow path 400 is a flow path that passes gas refrigerant accumulated in the receiver 150 and releases it to the suction injection pipe 320. The gas solenoid valve 420, which serves as a gas control valve, is an on-off valve that controls whether or not refrigerant is allowed to pass through the gas vent pipe 410, based on instructions from a control device 800, which will be described later. Here, instead of the gas solenoid valve 420, a throttle device that adjusts the flow rate or the like may be used as the gas control valve, which is an on-off valve.

[0035] The connection flow path 500 has a connection pipe 510 and a connection solenoid valve 520. One end of the connection pipe 510 is connected to the intermediate injection pipe 220, and the other end is connected to the suction injection pipe 320. The connection solenoid valve 520 is an on-off valve that controls whether or not refrigerant is allowed to pass through the connection pipe 510 based on an instruction from a control device 800 (described later). Here, instead of the connection solenoid valve 520, a throttle device that adjusts the flow rate or the like may be used as the connection control valve, which is an on-off valve.

[0036] The heat source unit 100 of the first embodiment has a connection flow path 500, and not only the refrigerant that has passed through the auxiliary heat exchanger 130, but also the refrigerant flowing through the suction injection pipe 320 can be passed through the connection pipe 510 and flow into the injection port 110A. Here, simply connecting the intermediate injection pipe 220 and the suction injection pipe 320 with the connection pipe 510 may result in refrigerant flowing from the intermediate injection flow path 200 to the suction injection flow path 300. In this case, the pressure of the refrigerant passing through the suction injection flow path 300 side of the subcooling heat exchanger 160 increases, and the saturation temperature also increases, which may result in insufficient heat exchange in the subcooling heat exchanger 160, and the refrigerant may not be supercooled. Therefore, the connection solenoid valve 520 is configured to control the passage of refrigerant through the connection pipe 510.

[0037] The connecting solenoid valve 520 in the connecting pipe 510 will be described. In FIG. 1 , in order to prioritize the depiction of the connection relationship in the refrigerant circuit, the connecting solenoid valve 520 is positioned above the suction injection pipe 320 and below the intermediate injection pipe 220. Here, for example, when the unit height direction of the heat source unit 100 is defined as the up-down direction, the direction perpendicular to the up-down direction is defined as the horizontal direction. Generally, it is desirable to install a solenoid valve so that refrigerant flows in from the horizontal direction relative to the valve body within the solenoid valve and flows out from the downward direction. Therefore, the connecting solenoid valve 520 is connected to the suction injection pipe 320 and is positioned so that refrigerant flows in from the horizontal direction of the connecting solenoid valve 520 relative to the connecting pipe 510, which is on the refrigerant inlet side of the connecting solenoid valve 520. Furthermore, the connecting solenoid valve 520 is connected to the intermediate injection pipe 220 via the connecting pipe 510, and is disposed so that the refrigerant flows out from the lower side of the connecting solenoid valve 520 in relation to the connecting pipe 510, which is the refrigerant outflow side of the connecting solenoid valve 520. Here, the inflow direction of the refrigerant does not have to be strictly horizontal, and the outflow direction of the refrigerant does not have to be strictly downward.

[0038] 2 is a diagram illustrating the control relationship in the refrigeration device 1 according to the first embodiment. The refrigeration device 1 according to the first embodiment has a control device 800. Here, it is assumed that the heat source unit 100 has the control device 800, but this is not limiting. The control device 800 has, for example, a microcomputer. The microcomputer has a control unit 810 and a storage unit 820. The control unit 810 has, for example, a control arithmetic processing device such as a CPU (Central Processing Unit). The control unit 810 also has an I / O port that manages the input and output of various signals.

[0039] The storage unit 820 also includes, for example, a volatile storage device (not shown) such as random access memory (RAM) that can temporarily store data, and a non-volatile auxiliary storage device (not shown) such as flash memory. The storage unit 820 stores, for example, data in the form of a program that describes the processing procedures to be performed by the control arithmetic processing unit. The control unit 810 then executes processing based on the program data. However, this is not a limitation, and the control device 800 may also be a device (hardware) dedicated to control.

[0040] Refrigeration system 1 has a detection unit 900. Detection unit 900 in embodiment 1 has a discharge pressure sensor 910, a suction pressure sensor 911, and an expansion valve pressure sensor 912. Detection unit 900 also has a discharge temperature sensor 920, a suction temperature sensor 921, a condenser temperature sensor 922, an auxiliary heat exchanger temperature sensor 923, an intermediate injection temperature sensor 924, and an outdoor temperature sensor 925. Each sensor detects a physical quantity and sends a signal including the value of the physical quantity to control device 800.

[0041] The discharge pressure sensor 910 detects the pressure of the refrigerant on the discharge side of the compressor 110. The pressure detected by the discharge pressure sensor 910 becomes the high-pressure pressure on the high-pressure side in the refrigerant circuit. The suction pressure sensor 911 detects the pressure of the refrigerant on the suction side of the compressor 110. The pressure detected by the suction pressure sensor 911 becomes the low-pressure pressure on the low-pressure side in the refrigerant circuit. The expansion valve pressure sensor 912 detects the pressure of the refrigerant flowing out from the heat source side expansion valve 140.

[0042] The discharge temperature sensor 920 detects the discharge temperature of the refrigerant on the discharge side of the compressor 110. The discharge temperature sensor 920 includes a thermistor or the like. It is assumed that the other temperature sensors described below also include a thermistor or the like. The suction temperature sensor 921 detects the suction temperature of the refrigerant on the suction side of the compressor 110. The condenser temperature sensor 922 detects the condensation temperature of the refrigerant flowing out from the heat source side heat exchanger 120. The auxiliary heat exchanger temperature sensor 923 detects the auxiliary condensation temperature of the refrigerant flowing out from the auxiliary heat exchanger 130 in the refrigerant circuit. The intermediate injection temperature sensor 924 detects the intermediate injection temperature of the refrigerant flowing out from the auxiliary heat exchanger 130 in the intermediate injection flow path 200. The outdoor temperature sensor 925 detects the outdoor temperature, which is the temperature around the heat source unit 100.

[0043] 3 is a diagram showing the flow of refrigerant under operating conditions of the refrigeration system 1 according to embodiment 1. FIG. 4 is a diagram illustrating the state of each solenoid valve under operating conditions of the refrigeration system 1.

[0044] When the refrigeration system 1 is operating, the control device 800 in the first embodiment controls the cooling capacity of the load unit 600 based on the evaporation temperature ET to improve capacity. At this time, when the cooling load is large, for example, when freezing the object to be cooled, the target evaporation temperature ETm of the refrigerant passing through the load-side heat exchanger 630 is set low. When the target evaporation temperature ETm of the refrigerant is low, the condensation capacity of the heat source unit 100 can be small. Therefore, there is no need to condense the refrigerant in the auxiliary heat exchanger 130, and there is no need to pass the refrigerant through the intermediate injection branch pipe 210.

[0045] However, there are cases where intermediate injection is desired when the discharge temperature of the refrigerant discharged from the compressor 110 is high. Therefore, as shown on the right side of FIG. 3 , the control device 800 turns on (opens) the connection solenoid valve 520, causing the refrigerant flowing through the suction injection pipe 320 to pass through the connection pipe 510 and be sent to the intermediate injection pipe 220. The refrigerant that has passed through the intermediate injection pipe 220 is intermediately injected from the injection port 110A of the compressor 110. Therefore, in the heat source unit 100, intermediate injection can be performed even when the intermediate injection solenoid valve 240 is turned off (closed). At this time, the control device 800 also turns off (closes) the intermediate injection solenoid valve 240 and the inlet-side solenoid valve 350. Furthermore, the suction injection solenoid valve 340 and the gas solenoid valve 420 are turned on (open). Here, if the inlet-side solenoid valve 350 is OFF (closed), the refrigerant flowing through the suction injection pipe 320 can be sent to the intermediate injection pipe 220 even if the intermediate injection solenoid valve 240 and the discharge temperature control valve 230 are ON (open). However, the performance improvement effect is greater if only the refrigerant flowing through the suction injection pipe 320 is intermediately injected from the injection port 110A. For this reason, it is desirable to turn the intermediate injection solenoid valve 240 OFF (closed).

[0046] On the other hand, when the cooling load is small, for example, when the cooling target is refrigerated, the target evaporation temperature ETm of the refrigerant passing through the load-side heat exchanger 630 is set high. In this case, as shown on the left side of FIG. 3 , the control device 800 turns on (opens) the intermediate injection solenoid valve 240 and passes the refrigerant through the intermediate injection branch pipe 210 and the intermediate injection pipe 220 to ensure the condensing capacity of the heat source unit 100. The refrigerant that has passed through the intermediate injection pipe 220 is intermediately injected from the injection port 110A of the compressor 110. At this time, the control device 800 also turns on (opens) the intermediate injection solenoid valve 240 and the inlet-side solenoid valve 350. The suction injection solenoid valve 340 and the gas solenoid valve 420 are set to the on (open) state.

[0047] Furthermore, when the subcooling heat exchanger 160 subcools the refrigerant, the control device 800 turns on (opens) the suction injection solenoid valve 340 to allow the refrigerant to pass through the suction injection pipe 320. At this time, the refrigerant pressure in the intermediate injection passage 200 is higher than that in the suction injection passage 300. Therefore, when the connection solenoid valve 520 is turned on (open), the refrigerant flowing through the intermediate injection passage 220 passes through the connection pipe 510 and flows into the suction injection pipe 320. Therefore, the subcooling heat exchanger 160 may not be able to subcool to the set subcooling degree. Therefore, the control device 800 controls the connection solenoid valve 520 to turn off (close) and separate the intermediate injection passage 200 from the suction injection passage 300.

[0048] 5 is a diagram showing a processing flow of the control device 800 in the first embodiment. The determination of the operating conditions in the control device 800 will be described with reference to FIG. 5. The control device 800 determines a target evaporation temperature ETm (step S1). Here, the target evaporation temperature ETm is determined based on a set temperature set for the air in the space to be cooled, a load, and the like.

[0049] Then, the control device 800 determines whether the target evaporation temperature ETm is equal to or higher than the opening / closing threshold temperature (step S2). The opening / closing threshold temperature is a temperature set for opening and closing the connection solenoid valve 520 based on the target evaporation temperature ETm, and is set to −15° C. in this example. However, the opening / closing threshold temperature is not limited to −15° C. and can be set arbitrarily.

[0050] When the control device 800 determines that the target evaporation temperature ETm is −15° C. or higher, it turns off (closes) the connection solenoid valve 520 (step S3). At this time, the control device 800 turns on (opens) the intermediate injection solenoid valve 240 and the inlet-side solenoid valve 350. Furthermore, the suction injection solenoid valve 340 and the gas solenoid valve 420 are kept on (open).

[0051] On the other hand, when the control device 800 determines that the target evaporation temperature ETm is less than −15° C., it turns on (opens) the connection solenoid valve 520 (step S4). At this time, the control device 800 turns off (closes) the intermediate injection solenoid valve 240 and the inlet-side solenoid valve 350. The suction injection solenoid valve 340 and the gas solenoid valve 420 are kept on (open).

[0052] As described above, in the refrigeration system according to the first embodiment, the heat source unit 100 is configured to connect the intermediate injection pipe 220 and the suction injection pipe 320 via the connection pipe 510, which is provided with the connection solenoid valve 520. The control device 800 switches the connection solenoid valve 520 between ON (open) and OFF (closed), allowing the refrigerant to pass from the suction injection pipe 320 to the intermediate injection pipe 220 via the connection pipe 510. This allows for flexible injection, such as intermediate injection of the refrigerant into the compressor 110 without condensing the refrigerant in the auxiliary heat exchanger 130, and allows the refrigeration system 1 to operate efficiently.

[0053] For example, when the control device 800 determines that the target evaporation temperature ETm is less than the opening / closing threshold temperature of −15° C., it turns on (opens) the connection solenoid valve 520 and performs intermediate injection by passing the air through the connection pipe 510. This allows the heat source unit 100 and the refrigeration device 1 having the heat source unit 100 to operate efficiently.

[0054] Embodiment 2. Fig. 6 is a diagram showing the flow of refrigerant when an intermediate injection blockage is detected in the refrigeration system 1 according to embodiment 2. Fig. 7 is a diagram explaining the state of each solenoid valve when an intermediate injection blockage is detected in the refrigeration system 1.

[0055] For example, if foreign matter or the like clogs the intermediate injection flow path 200, particularly in the discharge temperature control valve 230 where the flow path becomes narrow, causing the flow of refrigerant to become poor, intermediate injection becomes impossible. If intermediate injection becomes impossible, the discharge temperature of the compressor 110 may increase, potentially damaging the compressor 110. Therefore, the control device 800 detects the occurrence of intermediate injection clogging, for example, based on the temperature of the refrigerant flowing through the auxiliary heat exchanger 130 detected by the auxiliary heat exchanger temperature sensor 923.

[0056] When the control device 800 detects a blockage in the intermediate injection pipe, it turns on (opens) the connecting solenoid valve 520 and sends the refrigerant flowing through the suction injection pipe 320 through the connection pipe 510 to the intermediate injection pipe 220. The refrigerant that has passed through the intermediate injection pipe 220 is intermediately injected from the injection port 110A of the compressor 110. At this time, the control device 800 also turns off (closes) the intermediate injection solenoid valve 240 and the inlet-side solenoid valve 350. Furthermore, the suction injection solenoid valve 340 and the gas solenoid valve 420 are kept on (open).

[0057] As described above, according to the refrigeration system 1 of the second embodiment, when the control device 800 detects clogging of the intermediate injection, it turns on (opens) the connecting solenoid valve 520 to perform intermediate injection of the refrigerant passing through the suction injection pipe 320. Unlike the conventional system, the refrigeration system 1 of the second embodiment can continue to operate with intermediate injection without having to stop the compressor 110, thereby improving operating efficiency.

[0058] Embodiment 3 Fig. 8 is a diagram showing the flow of refrigerant in preventing liquid backflow in the refrigeration system 1 according to embodiment 3. Fig. 9 is a diagram for explaining the state of each solenoid valve in preventing liquid backflow in the refrigeration system 1.

[0059] For example, during transient operation, such as when the compressor 110 is started after a defrosting operation, if the refrigerant does not evaporate in the evaporator and the degree of superheat of the refrigerant on the refrigerant outlet side of the evaporator is low, liquid backflow occurs, in which liquid refrigerant or two-phase gas-liquid refrigerant is sucked back into the compressor 110. When liquid backflow occurs, the compressor 110 may be damaged when attempting to compress the liquid refrigerant, which has a high density, inside the compressor 110.

[0060] Therefore, for example, the control device 800 determines whether liquid backflow is occurring based on changes in the pressure, temperature, and other parameters of the refrigerant circuit detected by the sensors of the detection unit 900 when the compressor 110 is started. If the control device 800 determines that liquid backflow is occurring, it turns the suction injection solenoid valve 340 OFF (closed) and the gas solenoid valve 420 ON (open). Also, in this example, the intermediate injection solenoid valve 240 and the inlet solenoid valve 350 are ON (open), and the connecting solenoid valve 520 is OFF (closed). By releasing the gas refrigerant in the receiver 150 to the suction injection pipe 320, the gas refrigerant is released from the receiver 150 and the liquid refrigerant is stored in the receiver 150. This reduces the amount of liquid refrigerant circulating in the refrigerant circuit. Even if the subcooling control valve 330 is closed when liquid backflow occurs, the liquid backflow in the compressor 110 can be eliminated. However, if the intake injection flow path 300 is slowly closed by the subcooling adjustment valve 330, the liquid backflow may not be resolved, resulting in an abnormal stop, so it is desirable to install an intake injection solenoid valve 340.

[0061] As described above, in the refrigeration system 1 according to the third embodiment, when the control device 800 determines that liquid backflow is occurring, it turns on (opens) the gas solenoid valve 420 to allow the liquid refrigerant to accumulate in the receiver 150. This prevents the liquid refrigerant from returning to the suction side of the compressor 110, thereby improving resistance to liquid backflow.

[0062] Embodiment 4 Fig. 10 is a diagram showing the flow of refrigerant when preventing a high-pressure abnormality in the refrigeration system 1 according to embodiment 4. Fig. 11 is a diagram explaining the state of each solenoid valve when preventing a high-pressure abnormality in the refrigeration system 1.

[0063] For example, a high-pressure abnormality stop pressure is set in the refrigeration device 1, and when the control device 800 determines that the high-pressure pressure in the refrigerant circuit is equal to or greater than the high-pressure abnormality stop pressure, it stops operation of the heat source unit 100. The control device 800 normally performs control so as not to shut down the heat source unit 100 due to a high-pressure abnormality. Nevertheless, there are cases in which the high-pressure pressure in the refrigerant circuit rises abnormally during transient operation.

[0064] Therefore, for example, when the control device 800 determines based on the high-pressure abnormality stop pressure that the pressure is equal to or greater than the high-pressure abnormality set pressure that is set lower than the high-pressure abnormality stop pressure, it turns on (opens) the connection solenoid valve 520. When the connection solenoid valve 520 is turned on (opens), the refrigerant on the high-pressure side flows from the connection pipe 510 to the low-pressure side in the refrigerant circuit. At this time, the control device 800 also turns on (opens) the other solenoid valves.

[0065] As described above, in the refrigeration system 1 according to the fourth embodiment, when the control device 800 determines that the high-pressure side pressure is equal to or greater than the high-pressure abnormality setting pressure, it turns on (opens) the connecting solenoid valve 520. This allows the refrigerant on the high-pressure side in the refrigerant circuit to escape to the low-pressure side, suppressing an increase in the high-pressure side pressure. This prevents the pressure in the refrigerant circuit from becoming abnormal due to a high-pressure abnormality stop pressure, and prevents an abnormal stop of the heat source unit 100.

[0066] Fifth Embodiment Figure 12 is a diagram showing the configuration of a refrigeration system 1 according to a fifth embodiment. In the refrigeration system 1 shown in Figure 12, devices and the like having the same reference numerals as those in Figure 1 perform the same operations as those described in the first embodiment. As shown in Figure 12, the refrigeration system 1 according to the fifth embodiment differs from the configuration of the suction injection flow path 300 in Figure 1. In the refrigeration system 1 according to the fifth embodiment, the suction injection piping 320 is not only connected to the piping upstream of the check valve 171, but is also branched off and connected to the piping on the outflow side of the accumulator 170, with an outflow branch piping 360 having an outflow solenoid valve 370 installed therein.

[0067] The suction injection flow path 300 in the fifth embodiment further includes an outlet branch pipe 360 ​​and an outlet solenoid valve 370. One end of the outlet branch pipe 360 ​​is connected to the suction injection pipe 320, and the other end is connected to a pipe between the outlet side of the accumulator 170 and the suction side of the compressor 110. Therefore, the refrigerant that passes from the suction injection pipe 320 through the outlet branch pipe 360 ​​flows from the outlet side of the accumulator 170 to the suction side of the compressor 110. The outlet solenoid valve 370, which is a suction control valve that controls the passage of refrigerant flowing to the suction side of the compressor 110, is an on-off valve that, similar to the inlet solenoid valve 350, controls whether or not to allow refrigerant flowing through the suction injection pipe 320 to the suction side pipe of the compressor 110 to pass, based on an instruction from the control device 800 (described later). In particular, the outlet solenoid valve 370 controls whether or not to allow refrigerant flowing through the outlet branch pipe 360 ​​to pass through to the outlet side of the accumulator 170. Here, instead of the outflow side electromagnetic valve 370, a throttle device for adjusting the flow rate may be used as the outflow side control valve which is an opening / closing valve.

[0068] FIG. 13 is a diagram illustrating the flow of refrigerant during operation of the refrigeration system 1 according to the fifth embodiment. FIG. 14 is a diagram illustrating the state of each solenoid valve during operation of the refrigeration system 1. For example, when the amount of refrigeration oil contained in the refrigerant in the compressor 110 increases, a stator (not shown) mounted in the shell of the compressor 110 becomes immersed in the refrigeration oil, causing the temperature of the refrigeration oil to rise. Furthermore, high-temperature refrigeration oil is returned from the oil separator 111. Therefore, high-temperature refrigerant is drawn into the compressor 110 on the suction side. If the refrigerant temperature remains high for a long period of time, this can lead to damage to components inside the shell of the compressor 110.

[0069] Therefore, when the control device 800 determines that the suction temperature detected by the suction temperature sensor 921 is equal to or higher than the suction threshold temperature, it turns on (opens) the outlet solenoid valve 370 and turns off (closes) the inlet solenoid valve 350 in the suction injection flow path 300. As a result, refrigerant at a temperature lower than that of the refrigerant flowing out from the accumulator 170 is drawn into the compressor 110 via the outlet branch pipe 360.

[0070] For example, a gas-liquid two-phase refrigerant flows through the suction injection flow path 300. The refrigerant suction-injected through the inlet-side solenoid valve 350 passes through the accumulator 170, resulting in gas refrigerant being drawn into the compressor 110, and the sensible heat of the refrigerant cools the compressor 110. On the other hand, the refrigerant suction-injected through the outlet-side solenoid valve 370 is a gas-liquid two-phase refrigerant, and therefore cools the compressor 110 with the refrigerant's latent heat as well. This allows the temperature inside the compressor 110 to be efficiently reduced. This protects the compressor 110, improving the reliability of the compressor 110, the heat source unit 100, and the refrigeration system 1. At this time, the intermediate injection solenoid valve 240, the suction injection solenoid valve 340, and the gas solenoid valve 420 are in the ON (open) state, and the connection solenoid valve 520 is in the OFF (closed) state.

[0071] Sixth embodiment Fig. 15 is a diagram showing the flow of refrigerant under conditions related to the operation of the refrigeration system 1 according to the sixth embodiment. Fig. 16 is a diagram explaining the state of each solenoid valve under conditions related to the operation of the refrigeration system 1. The configuration of the refrigeration system 1 according to the sixth embodiment is the same as that of the refrigeration system 1 according to the fifth embodiment.

[0072] For example, if the outside air temperature becomes high while the heat source unit 100 is not operating, the liquid refrigerant accumulated in the receiver 150 may evaporate, causing the refrigerant pressure to rise within the heat source unit 100, particularly on the high-pressure side of the refrigerant circuit that is the discharge side of the compressor 110. At this time, if there is a large amount of refrigerant within the heat source unit 100, the pressure may exceed the design pressure resistance that is preset for the heat source unit 100.

[0073] Therefore, when the control device 800 determines that the high-pressure pressure detected by the discharge pressure sensor 910 is equal to or greater than the shutdown pressure setting, which is set at a pressure lower than the design pressure limit, it turns on (opens) the outlet solenoid valve 370. With the outlet solenoid valve 370 turned on (opens), the refrigerant on the high-pressure side of the refrigerant circuit, which is the discharge side of the compressor 110, flows to the low-pressure side. When the refrigerant on the high-pressure side flows to the low-pressure side, the accumulator 170 installed on the low-pressure side increases the refrigerant storage volume, thereby decreasing the pressure on the high-pressure side. Here, the control device 800 turns on (opens) the intermediate injection solenoid valve 240, the suction injection solenoid valve 340, and the gas solenoid valve 420, ensuring the volume of the piping for each flow path. The connection solenoid valve 520 is turned off (closed).

[0074] For example, when the outside air temperature is high or there is a large amount of refrigerant on the high-pressure side of the refrigerant circuit, the pressure on the high-pressure side may not decrease even if the outlet solenoid valve 370 is turned on (opened). Therefore, when the control device 800 determines that the high-pressure pressure will not fall below the shutdown set pressure within a predetermined set time, it also turns on (opens) the inlet solenoid valve 350. By turning on (opening) the inlet solenoid valve 350, refrigerant is released to the gas refrigerant extension pipe 720 and the load unit 600, thereby reducing the pressure on the high-pressure side throughout the entire refrigerant circuit.

[0075] Here, particularly when the refrigeration system 1 is stopped after the pump-down operation, the inlet-side solenoid valve 350 is installed on the gas refrigerant extension pipe 720 side, which is upstream of the check valve 171, so the suction pressure sensor 911 detects an increase in the low-pressure pressure. Therefore, when the control device 800 determines that the low-pressure pressure detected by the suction pressure sensor 911 is equal to or greater than a predetermined low-pressure threshold, it turns on the thermostat and operates the refrigeration system 1. This allows the pressure on the high-pressure side of the refrigerant circuit to decrease.

[0076] As described above, according to the refrigeration system 1 of the sixth embodiment, when the control device 800 determines that the high-pressure pressure is equal to or greater than the shutdown set pressure while the heat source unit 100 of the refrigeration system 1 is stopped, it turns on (opens) the outlet solenoid valve 370 to release the refrigerant to the low-pressure side of the refrigerant circuit. This prevents the refrigerant pressure from becoming abnormally high in part of the refrigerant circuit. This protects the heat source unit 100 and the refrigeration system 1 and improves their reliability. Furthermore, if the pressure still does not decrease, the inlet solenoid valve 350 can also be turned on (opened) to reduce the high-pressure side pressure throughout the entire refrigerant circuit.

[0077] In the above-described first to sixth embodiments, the heat source unit 100 is described as being applied to the refrigeration device 1, but it can also be applied to other refrigeration cycle devices, such as a refrigerator.

[0078] 1 Refrigeration device, 100 Heat source unit, 110 Compressor, 110A Injection port, 111 Oil separator, 120 Heat source side heat exchanger, 130 Auxiliary heat exchanger, 140 Heat source side expansion valve, 150 Receiver, 160 Subcooling heat exchanger, 170 Accumulator, 171 Check valve, 180 Heat source side fan, 200 Intermediate injection flow path, 210 Intermediate injection branch pipe, 220 Intermediate injection pipe, 230 Discharge temperature control valve, 240 Intermediate injection solenoid valve, 300 Intake injection flow path, 310 Intake injection branch pipe, 320 Intake injection pipe, 330 Subcooling control valve, 340 Intake injection solenoid valve, 350 Inlet side solenoid valve, 360 Outlet side branch pipe, 370 Outlet side solenoid valve, 400 Receiver flow path, 410 gas vent pipe, 420 gas solenoid valve, 500 connection flow path, 510 connection pipe, 520 connection solenoid valve, 600 load unit, 610 load side expansion valve, 620 load side solenoid valve, 630 load side heat exchanger, 640 load side fan, 710 liquid refrigerant extension pipe, 720 gas refrigerant extension pipe, 800 control device, 810 control unit, 820 memory unit, 900 detection unit, 910 discharge pressure sensor, 911 suction pressure sensor, 912 expansion valve pressure sensor, 920 discharge temperature sensor, 921 suction temperature sensor, 922 condenser temperature sensor, 923 auxiliary heat exchanger temperature sensor, 924 intermediate injection temperature sensor, 925 outdoor temperature sensor.

Claims

1. A heat source unit that is connected to a load unit having a load-side expansion valve and an evaporator through a pipe and that constitutes a refrigerant circuit that circulates a refrigerant, a compressor having an injection port for introducing the refrigerant, and suctioning, compressing, and discharging the refrigerant; a condenser that condenses the refrigerant by heat exchange; a receiver that stores the refrigerant that has passed through the condenser; an intermediate injection flow path including an intermediate injection pipe and an intermediate injection control valve that controls the passage of the refrigerant through the intermediate injection pipe, and that guides a portion of the refrigerant flowing from the condenser to the receiver in the refrigerant circuit to the injection port of the compressor; an intake injection flow path including an intake injection pipe and an intake injection control valve that controls the passage of the refrigerant through the intake injection pipe, and that guides a portion of the refrigerant flowing from the receiver toward the evaporator to the intake side of the compressor in the refrigerant circuit; a heat source unit comprising a connection pipe that connects the intermediate injection pipe and the suction injection pipe, and a connection flow path having a connection control valve that controls the passage of the refrigerant through the connection pipe;

2. The heat source unit according to claim 1 , wherein the connection control valve is controlled to open and close based on a target evaporation temperature of the evaporator.

3. the intake injection flow path includes a suction side control valve that controls the passage of the refrigerant flowing to the suction side of the compressor, The suction side control valve is closed when the target evaporation temperature is less than an opening / closing threshold temperature, The heat source unit according to claim 2 , wherein the connection control valve is closed when the target evaporation temperature is equal to or higher than the opening / closing threshold temperature, and is opened when the target evaporation temperature is lower than the opening / closing threshold temperature.

4. The heat source unit described in any one of claims 1 to 3, wherein the connection control valve has a valve body and is installed so that the refrigerant flows into the valve body from a horizontal direction perpendicular to the unit height direction and the refrigerant flows out below the valve body.

5. The heat source unit according to any one of claims 1 to 3, wherein the connection control valve is opened when an injection blockage occurs in the intermediate injection flow path.

6. a receiver flow path having a gas vent pipe that causes gas refrigerant accumulated in the receiver to flow into the suction injection pipe and a gas control valve that controls the passage of the gas refrigerant through the gas vent pipe, A heat source unit as described in any one of claims 1 to 3, wherein the gas control valve is opened when liquid backflow occurs in which liquid refrigerant or gas-liquid two-phase refrigerant is sucked into the compressor, and the connection control valve is closed.

7. a discharge pressure sensor for detecting a high pressure on the discharge side of the compressor; 4. The heat source unit according to claim 1, wherein the connection control valve is opened when the high-pressure pressure detected by the discharge pressure sensor is equal to or greater than a high-pressure abnormality setting pressure.

8. an accumulator is provided on the suction side of the compressor to accumulate the refrigerant that has passed through the evaporator; an inlet-side control valve that controls passage of the refrigerant flowing through the intermediate injection pipe to a refrigerant inlet-side pipe of the accumulator; A heat source unit according to any one of claims 1 to 3, wherein an outlet side control valve that controls the passage of the refrigerant flowing through the intermediate injection pipe to the refrigerant outlet side pipe of the accumulator is installed in the intake injection flow path.

9. an intake temperature sensor for detecting an intake temperature of the refrigerant on the intake side of the compressor; The heat source unit according to claim 8 , wherein when an intake temperature of the refrigerant drawn into the compressor is equal to or higher than an intake threshold temperature, the outlet control valve is opened and the inlet control valve is closed.

10. a discharge pressure sensor for detecting a high pressure on the discharge side of the compressor; The heat source unit according to claim 8, wherein when the operation is stopped, the connection control valve and the outlet side control valve are opened when the high pressure detected by the discharge pressure sensor is equal to or higher than a set pressure at the time of stop.

11. The heat source unit according to claim 10, wherein the inlet-side control valve is opened when the high-pressure pressure on the high-pressure side of the refrigerant circuit does not decrease within a preset time.

12. The heat source unit according to any one of claims 1 to 3, a load unit having a load-side expansion valve and an evaporator; A refrigeration cycle device comprising: