EP4239262A1

EP4239262A1 - Refrigeration cycle device

Info

Publication number: EP4239262A1
Application number: EP21885841.3A
Authority: EP
Inventors: Shingo TOHYAMA; Takeru Morita
Original assignee: Toshiba Carrier Corp
Current assignee: Carrier Japan Corp
Priority date: 2020-10-30
Filing date: 2021-10-06
Publication date: 2023-09-06
Also published as: WO2022091722A1; KR20230074577A; JP7551769B2; JPWO2022091722A1; EP4239262A4

Abstract

This refrigeration cycle device is provided with a refrigerant circuit through which a refrigerant circulates, the refrigeration cycle device comprising a compressor that discharges a gas-phase refrigerant, a heat-source-side heat exchanger, a first expansion valve, a use-side heat exchanger, and an injection channel through which a portion of a liquid-phase refrigerant is distributed and injected into the compressor. In the injection channel, an electromagnetic valve, a check valve, and a second expansion valve are disposed, in that order from the upstream side of the flowing direction of the liquid-phase refrigerant in the injection channel. The second expansion valve enters a stopped state without being fully closed and having an aperture larger than the full closure.

Description

Technical Field

Embodiments of the present invention relate to a refrigeration cycle device.

Background Art

A refrigeration cycle device is configured by including a compressor, a condenser, an expansion valve, and an evaporator as main elements. For example, during a warming operation or a heating operation, the refrigeration cycle device absorbs heat from outside air with an evaporator and supplies that heat to indoor air or hot water with a condenser. At this time, the higher the outside air temperature, the greater the amount of heat absorbed by the evaporator, and the higher the temperature and pressure of the refrigerant sucked into the compressor. If the compressor becomes an overheated state as a result, a discharge refrigerant temperature of the compressor may rise excessively. Such an increase in the discharge refrigerant temperature can, for example, lower the viscosity of lubricating oil that lubricates a compression mechanism unit of the compressor and cause damage to a motor in the compressor. Therefore, various measures have been taken to prevent such a rise in discharge refrigerant temperature.
One example is to add an injection flow path, which leads part of a liquid-phase refrigerant to the compressor, to a refrigerant circulation path. The injection flow path is connected between the condenser and the expansion valve in the circulation path and is configured by including a check valve, a two-way valve, and an expansion valve (expansion valve for injection flow path), etc. By using the injection flow path, part of the liquid-phase refrigerant that has passed through the condenser is injected into a cylinder chamber of the compressor, and a gas-phase refrigerant sucked into the compressor is cooled by the liquid-phase refrigerant. This prevents the compressor from becoming an overheated state.
Such an injection flow path is controlled to open and close a circuit according to, for example, the outside air temperature. In a case where the injection flow path is closed after being opened, or in the event of a power failure, etc., the liquid-phase refrigerant becomes a sealed state (liquid sealed state) in the injection flow path. When the outside air temperature (ambient temperature) rises in the liquid sealed state, the liquid-phase refrigerant expands inside the injection flow path. For example, if the liquid-phase refrigerant expands between the two-way valve and the check valve in the injection flow path, depending on the degree of expansion, piping may be damaged between these valves in the liquid sealed state. Therefore, in the case where an injection flow path is installed, it is necessary to configure the piping so that such a liquid sealed state does not occur.

Citation List

Patent Literature

Patent Literature 1: JP 6514964 B

Summary of Invention

Technical Problem

Embodiments described herein aim to provide a refrigeration cycle device comprising an injection flow path that can avoid a liquid sealed state with relatively simple piping, without complicating the piping.

Solution to Problem

A refrigeration cycle device according to one embodiment includes a refrigerant circuit in which a refrigerant circulates. The refrigerant circulates is configured by including a compressor that discharges a gas-phase refrigerant, a heat source-side heat exchanger, a first expansion valve, a user-side heat exchanger, and an injection flow path that diverts part of a liquid-phase refrigerant and injects it into the compressor. In the injection flow path, a solenoid valve, a check valve, and a second expansion valve are arranged in order from an upstream side in a flow direction of the liquid-phase refrigerant in the injection flow path. The second expansion valve is not fully closed, but is characterized in that it becomes a stopped state at an opening angle greater than fully closed.

Brief Description of Drawings

FIG. 1 is a circuit diagram schematically showing a refrigeration cycle of a refrigeration cycle device (air-cooled heat pump chilling unit) according to an embodiment.
FIG. 2 is a control flow diagram during open/close control of an injection flow path in the refrigeration cycle device (air-cooled heat pump chilling unit) according to the embodiment.
FIG. 3 schematically shows the flow of part of a liquid-phase refrigerant in a state where the injection flow path is opened in a cooling mode of the refrigeration cycle device (air-cooled heat pump chilling unit) according to the embodiment.
FIG. 4 schematically shows the flow of part of the liquid-phase refrigerant in a state where the injection flow path is opened in a heating mode of the refrigeration cycle device (air-cooled heat pump chilling unit) according to the embodiment.
FIG. 5 schematically shows the flow of part of the liquid-phase refrigerant in a state where the injection flow path is closed in the refrigeration cycle device (air-cooled heat pump chilling unit) according to the embodiment.
FIG. 6 is a circuit diagram schematically showing another form of the refrigeration cycle of the refrigeration cycle device (air-cooled heat pump chilling unit) according to the embodiment.

Mode for Carrying Out the Invention

One embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a circuit diagram showing a refrigeration cycle of an air-cooled heat pump chilling unit (hereinafter simply referred to as a chilling unit) 1 according to the embodiment. The chilling unit 1 is an example of a refrigeration cycle device, which can be operated in a cooling mode and a heating mode, respectively. Note that the refrigeration cycle device is not limited to the chilling unit 1 with a refrigeration cycle as shown in FIG. 1, but may be, for example, an air conditioner or a water-cooled heat source unit.
As shown in FIG. 1, the chilling unit 1 comprises a refrigeration cycle unit 2, a water circuit unit 5, a controller 7, and an operation unit 8.
The refrigeration cycle unit 2 is configured by a refrigerant circuit R comprising a compressor 20, a four-way valve 21, an air heat exchanger unit 22, a pair of expansion valves (first expansion valves) 23a and 23b, a receiver 24, a water heat exchanger (user-side heat exchanger) 25, and a gas-liquid separator 26 as principal elements. Each of these elements of the refrigerant circuit R is connected via a main pipe 27 through which the refrigerant circulates.
For example, the compressor 20 is of a variable capacity type, and discharges a high-temperature and high-pressure gas-phase refrigerant from a discharge outlet. The discharge outlet of the compressor 20 is connected to a first port 21a of the four-way valve 21 via a discharge pipe 28. The discharge pipe 28 is provided with a first temperature sensor (detector) T1 that detects the temperature of the high-temperature and high-pressure gas-phase refrigerant and a first pressure sensor P1 that detects the pressure of the high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 20.
A second port 21b of the four-way valve 21 is connected to the air heat exchanger unit 22. As an example in the present embodiment, the air heat exchanger unit 22 comprises a pair of air heat exchangers 29a and 29b and a fan 30. The air heat exchangers 29a and 29b correspond to heat source-side heat exchangers. In the air heat exchanger unit 22, the air heat exchangers 29a and 29b configure an exhaust passage extending in a vertical direction between them and a shielding plate. The fan 30 is supported by an upper end portion of the air heat exchangers 29a and 29b via a support member so as to be located at an exhaust port opening at the upper end of such exhaust passage.
In the air heat exchanger unit 22, when the fan 30 is driven, outside air is sucked through the air heat exchangers 29a and 29b and into the exhaust passage. The outside air sucked into the exhaust passage is drawn up toward the exhaust port and discharged from the exhaust port to the upper part of the air heat exchanger unit 22.
Inlets of the air heat exchangers 29a and 29b are connected in parallel to the second port 21b of the four-way valve 21. Near the inlets of the air heat exchangers 29a and 29b are provided second temperature sensors T2 that detect the temperature of the gas-phase refrigerant flowing into the air heat exchangers 29a and 29b, respectively. Note that such inlets are flow inlets through which the refrigerant flows into the air heat exchangers 29a and 29b in the cooling mode described below, and become flow outlets through which the refrigerant flows out (outlets of the air heat exchangers 29a and 29b) in the heating mode.
Outlets of the air heat exchangers 29a and 29b are connected to pipes 41a and 41b including the expansion valves 23a and 23b. The pipes 41a and 41b merge with each other downstream of the expansion valves 23a and 23b and are connected to a single collective pipe 42. The collective pipe 42 is connected to a third port 21c of the four-way valve 21 via the receiver 24 and the water heat exchanger 25. Note that such outlets are flow outlets from which the refrigerant flows out of the air heat exchangers 29a and 29b in the cooling mode described below, and become flow inlets from which the refrigerant flows in (inlets of the air heat exchangers 29a and 29b) in the heating mode.
A fourth port 21d of the four-way valve 21 is connected to a suction side of the compressor 20 via the gas-liquid separator 26. In a pipe 43 connecting the fourth port 21d of the four-way valve 21 to the inlet of the gas-liquid separator 26, a third temperature sensor T3 is provided to detect the temperature of the gas-liquid two-phase refrigerant being led to the gas-liquid separator 26.
Furthermore, in a pipe 44 connecting the outlet of the gas-liquid separator 26 and the suction side of the compressor 20, a second pressure sensor P2 is provided to detect the pressure of a low-temperature and low-pressure gas-phase refrigerant being sucked into the compressor 20.
In addition, a pipe 46 is provided between the gas-liquid separator 26 and the four-way valve 21. The pipe 46 connects the inlet of the gas-liquid separator 26 and the first port 21a of the four-way valve 21, and a normally-closed solenoid valve 47 is provided in the middle of the pipe 46.
The water heat exchanger 25 comprises a refrigerant flow path 25a and a water flow path 25c. The refrigerant flow path 25a is connected to the collective pipe 42 downstream in the cooling mode described below and upstream in the heating mode described below with respect to the receiver 24.
In addition to these configurations, the refrigerant circuit R comprises an injection flow path 6. The injection flow path 6 is configured by including three flow paths (hereinafter referred to as first to third injection flow paths) 6a, 6b, and 6c. The first injection flow path 6a and the second injection flow path 6b are flow paths that branch the refrigerant circuit R, respectively. The third injection flow path 6c is a flow path where the first injection flow path 6a and the second injection flow path 6b merge.
The first injection flow path 6a is a flow path of a high-pressure liquid-phase refrigerant condensed by heat exchange with outside air passing through the air heat exchangers 29a and 29b. One end of the first injection flow path 6a is connected between the air heat exchanger 29b and the expansion valve 23b. As a result, the first injection flow path 6a branches off from the pipe 41b between the air heat exchanger 29b and the expansion valve 23b, that is, on the downstream side of the air heat exchanger 29b and on the upstream side of the expansion valve 23b in the flow direction of the liquid-phase refrigerant.
The second injection flow path 6b is a flow path of a high-pressure liquid-phase refrigerant that has passed through the water heat exchanger 25 after heat exchange with water flowing in the water flow path 25c. One end of the second injection flow path 6b is connected between the water heat exchanger 25 and the receiver 24. As a result, the second injection flow path 6b branches off from the collective pipe 42 between the water heat exchanger 25 and the receiver 24, that is, on the downstream side of the water heat exchanger 25 and on the upstream side of the receiver 24 (in other words, the expansion valves 23a and 23b) in the flow direction of the liquid-phase refrigerant.
The third injection flow path 6c is a flow path in which the first injection flow path 6a and the second injection flow path 6b merge and the high-pressure liquid-phase refrigerant flows. In other words, the first injection flow path 6a and the second injection flow path 6b are arranged on the upstream side and the third injection flow path 6c is arranged on the downstream side in the flow direction of the liquid-phase refrigerant. The third injection flow path 6c is such that one end is connected to the other end of the first injection flow path 6a and the other end of the second injection flow path 6b, and the other end is connected to the injection port 20a of the compressor 20.
With these injection flow paths 6a, 6b, and 6c, part of the liquid-phase refrigerant is injected into a cylinder chamber of the compressor 20 (not shown), and a high-temperature gas-phase refrigerant sucked into the compressor 20 is cooled by such liquid-phase refrigerant. This prevents the compressor 20 from overheating. In the injection flow path 6, solenoid valves 61a and 61b, check valves 62a and 62b, and an expansion valve (second expansion valve) 60c are arranged in order from the upstream side in the flow direction of the liquid-phase refrigerant.
Here, an operation for cooling by injecting a liquid-phase refrigerant into a cylinder chamber of the compressor 20 via the injection flow paths 6a, 6b, and 6c is called a liquid injection operation.
The first injection flow path 6a is provided with the solenoid valve (hereinafter referred to as a solenoid valve for cooling) 61a and the check valve (hereinafter referred to as a check valve for cooling) 62a. In the flow direction of the liquid-phase refrigerant in the first injection flow path 6a, the solenoid valve 61a for cooling is arranged on the upper stream side of the check valve 62a for cooling. In the first injection flow path 6a, in a case where the chilling unit 1 is operated in the cooling mode (cooling operation), part of the liquid-phase refrigerant branches off from the pipe 41b and flows as necessary.
The second injection flow path 6b is provided with the solenoid valve (hereinafter referred to as a solenoid valve for heating) 61b and the check valve (hereinafter referred to as a check valve for heating) 62b. In the flow direction of the liquid-phase refrigerant in the second injection flow path 6b, the solenoid valve 61b for heating is arranged on the upper stream side of the check valve 62b for heating. In the second injection flow path 6b, in a case where the chilling unit 1 is operated in the heating mode (heating operation), part of the liquid-phase refrigerant branches off from the collective pipe 42 and flows as necessary.
The third injection flow path 6c is provided with the expansion valve (second expansion valve) 60c. The expansion valve 60c is an electronic valve and is a closed valve-less valve. The closed valve-less valve has a valve structure that does not fully close, but becomes a stopped state at an opening degree greater than the fully closed (hereinafter referred to as a stop opening degree). In other words, the expansion valve 60c remains open by the stop opening degree even in the stopped state and does not cause the flow of liquid-phase refrigerant to be blocked. The high-pressure liquid-phase refrigerant that has passed through the first injection flow path 6a or the second injection flow path 6b flows into the third injection flow path 6c. The high-pressure liquid-phase refrigerant flowing into the third injection flow path 6c is depressurized in the process of passing through the expansion valve 60c and is injected into the cylinder chamber from the injection port of the compressor 20.
The water circuit unit 5 is a flow path for water that exchanges heat with the refrigerant in the water heat exchanger 25, and comprises as main elements a water circulation pump 50 and first to third water pipes 51a, 51b, and 51c.
The water circulation pump 50 is, for example, of a variable capacity type and has a suction inlet connected to one end of the first water pipe 51a and a discharge outlet connected to one end of the second water pipe 51b. The other end of the first water pipe 51a is connected to a water outlet on a utilization equipment side of the chilling unit 1. The other end of the second water pipe 51b is connected to the inlet of the water flow path 25c of the water heat exchanger 25. The second water pipe 51b is provided with a third pressure sensor P3 to detect water pressure and a fourth temperature sensor T4 to detect water temperature. The third water pipe 51c is such that one end is connected to the outlet of the water flow path 25c and the other end is connected to the water inlet on the utilization equipment side of the chilling unit 1. The third water pipe 51c is provided with a fourth pressure sensor P4 to detect water pressure and a fifth temperature sensor T5 to detect water temperature.
The controller 7 controls the operation of each element of the refrigeration cycle unit 2 and the water circuit unit 5 and controls the operation of the chilling unit 1. The controller 7 includes a CPU, a memory, a storage device (nonvolatile memory), an input/output circuit, a timer, etc., and controls the operation of the chilling unit 1 by controlling the operation of each element of the refrigeration cycle unit 2 and the water circuit unit 5. For example, the controller 7 acquires various information (data) necessary to control the operation of the chilling unit 1, such as a start operation and a stop operation of the chilling unit 1, mode selection between the cooling operation and the heating operation, temperature, pressure, water temperature, and water pressure of the refrigerant. By executing predetermined arithmetic processing according to the acquired information, the controller 7 controls the operation of each of the above elements, starts operation and stops operation of the chilling unit 1, switches between the cooling operation and the heating operation, and opens and closes the injection flow path 6, etc. Specifically, the controller 7 controls each of the operations of operating and stopping the compressor 20, switching the ports of the four-way valve 21, opening and closing the expansion valves 23a and 23b, the expansion valve 60c, the solenoid valve 61a for cooling, and the solenoid valve 61b for heating.
The operation unit 8 includes, for example, a panel, a switch, a button, and a display for displaying and is wired or wirelessly connected to the controller 7. The operation unit 8 is an interface through which predetermined operations are performed by a user, such as starting operation of the chilling unit 1, selecting the mode of a cooling operation or a heating operation, and setting a water supply temperature, etc.
The operation of the chilling unit 1 when in the cooling mode and the heating mode will be described.
For example, in a case where the chilling unit 1 operates in the cooling mode, the four-way valve 21 switches so that the first port 21a is connected to the second port 21b and the third port 21c is connected to the fourth port 21d, as shown in solid lines in FIG. 1.
The compressor 20 then operates, and a high-temperature and high-pressure gas-phase refrigerant is discharged from the compressor 20 into the discharge pipe 28. The high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 20 is led to the air heat exchangers 29a and 29b via the four-way valve 21.
The gas-phase refrigerant led to the air heat exchangers 29a and 29b exchanges heat with the outside air passing through the air heat exchangers 29a and 29b due to the operation of the fan 30, condenses, and changes into a high-pressure liquid-phase refrigerant. The high-pressure liquid-phase refrigerant is depressurized in the process of passing through the expansion valves 23a and 23b, and changes to an intermediate-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is led through the receiver 24 to the water heat exchanger 25. The gas-liquid two-phase refrigerant led to the water heat exchanger 25 exchanges heat with water flowing in the water flow path 25c. As a result, the water in water flow path 25c becomes chilled water by depriving it of latent heat. The chilled water is supplied from the third water pipe 51c to the utilization equipment side.
The low-temperature and low-pressure gas-liquid two-phase refrigerant that has passed through the water heat exchanger 25 is led through the four-way valve 21 to the gas-liquid separator 26 and is separated into a liquid-phase refrigerant and a gas-phase refrigerant by the gas-liquid separator 26. The gas-phase refrigerant separated from the liquid-phase refrigerant is sucked into the compressor 20 and is discharged from the compressor 20 as a high-temperature and high-pressure gas-phase refrigerant again.
On the other hand, in the case where the chilling unit 1 operates in the heating mode, the four-way valve 21 switches so that the first port 21a is connected to the third port 21c and the second port 21b is connected to the fourth port 21d, as shown in broken lines in FIG. 1.
When operation is started in the heating mode, the high-temperature and high-pressure gas-phase refrigerant compressed by the compressor 20 is led to the water heat exchanger 25 via the four-way valve 21. The gas-phase refrigerant led to the water heat exchanger 25 and flowing in the refrigerant flow path 25a exchanges heat with the water flowing in the water flow path 25c. As a result, the water in the water flow path 25c is heated to become hot water. The hot water is supplied from the third water pipe 51c to the utilization equipment side.
The high-pressure liquid-phase refrigerant that has passed through the water heat exchanger 25 changes to an intermediate-pressure gas-liquid two-phase refrigerant in the process of passing through the receiver 24 and the expansion valves 23a and 23b, and is led to the air heat exchangers 29a and 29b. The gas-liquid two-phase refrigerant led to the air heat exchangers 29a and 29b evaporates by exchanging heat with the outside air passing through the air heat exchangers 29a and 29b due to the operation of the fan 30, and changes into a low-temperature and low-pressure gas-liquid two-phase refrigerant.
The low-temperature and low-pressure gas-liquid two-phase refrigerant that has passed through the air heat exchangers 29a and 29b is led through the four-way valve 21 to the gas-liquid separator 26 and is separated into a liquid-phase refrigerant and a gas-phase refrigerant by the gas-liquid separator 26. The gas-phase refrigerant separated from the liquid-phase refrigerant is sucked into the compressor 20 and is discharged from the compressor 20 as a high-temperature and high-pressure gas-phase refrigerant again.
Here, as an example of the operation control in the chilling unit 1, an operation control focusing on the open/close control of the injection flow path 6 in the refrigerant circuit R will be described according to the control flow of the controller 7. The open/close control of the injection flow path 6 controls the injection of the liquid-phase refrigerant into the compressor 20. FIG. 2 shows the control flow of the controller 7 during the open/close control of injection flow path 6.
In a state where the chilling unit 1 has started operating, the controller 7 controls the opening and closing of the injection flow path 6 as follows. In controlling the opening and closing of the injection flow path 6, the controller 7 determines the operation mode of the chilling unit 1. As an example, in the control flow shown in FIG. 2, the controller 7 determines whether or not the operation mode of the chilling unit 1 is the cooling mode (S101). In doing so, the controller 7 receives a signal indicating the operation mode from the operation unit 8, for example, and, in the case where the received signal is a cooling mode selection signal, the operation mode is the cooling mode; otherwise, the operation mode is determined as not being the cooling mode.
In the case where the operation mode is the cooling mode, the controller 7 causes the chilling unit 1 to operate in the cooling mode (S102). In this case, the controller 7 operates and controls the four-way valve 21, connects the first port 21a and the second port 21b, connects the third port 21c and the fourth port 21d, and operates the compressor 20.
Next, the controller 7 determines an open flow path enabling/disabling condition of the injection flow path 6 (S103). The open flow path enabling/disabling condition is a condition for determining whether or not to open the injection flow path 6. Here, the open flow path enabling/disabling condition is determined according to whether or not a temperature (Td) of the refrigerant discharged from the compressor 20 is a predetermined temperature (T0) or lower. The temperature of the refrigerant discharged from the compressor 20 (hereinafter referred to as a discharge refrigerant temperature Td) is the temperature of the refrigerant detected by the first temperature sensor T1. The predetermined temperature (hereinafter referred to as a reference temperature T0) is a threshold value for determining whether or not the discharge refrigerant temperature Td is excessively elevated, or in other words, whether or not the compressor 20 is in an overheated state. The value of the reference temperature T0 is predetermined according to the performance of the compressor 20, for example, and is stored in the memory device of the controller 7 and read out into the memory as a parameter when determining the open flow path enabling/disabling condition. As an example, in the present embodiment, the value of the reference temperature T0 is assumed to be about 100°C, but it is not limited to such values. The reference temperature T0 may be a fixed value, or it may be a variable value that changes according to, for example, a set water supply temperature.
In determining the open flow path enabling/disabling condition, the controller 7 acquires the detected value of the discharge refrigerant temperature Td from the first temperature sensor T1 and compares the acquired value with the reference temperature T0. In the case where the discharge refrigerant temperature Td exceeds the reference temperature T0 (Td > T0), the controller 7 determines that the open flow path enabling/disabling condition is satisfied, and, in the case where the discharge refrigerant temperature Td is the reference temperature T0 or lower (Td ≤ T0), it determines that the open flow path enabling/disabling condition is not satisfied.
In the case where the open flow path enabling/disabling condition is not satisfied (Td ≤ T0), the controller 7 closes the injection flow path 6. In this case, the controller 7 closes the solenoid valve 61a for cooling of the first injection flow path 6a and, also, closes the solenoid valve 61b for heating of the second injection flow path 6b (S104). For example, in the case where the solenoid valve 61a for cooling or the solenoid valve 61b for heating is open, the controller 7 closes the valve. On the other hand, in the case where the solenoid valve 61a for cooling and the solenoid valve 61b for heating are closed, the controller 7 maintains this state. The controller 7 also places the expansion valve 60c in a stopped state (S104). For example, in the case where the expansion valve 60c is not in the stopped state, the controller 7 places the expansion valve 60c in the stopped state. On the other hand, in the case where the expansion valve 60c is in the stopped state, the controller 7 maintains this state.
In contrast, in the case where the open flow path enabling/disabling condition is satisfied (Td > T0), the controller 7 opens the injection flow path 6. In this case, the controller 7 opens the solenoid valve 61a for cooling in the first injection flow path 6a and closes the solenoid valve 61b for heating in the second injection flow path 6b (S105). For example, in the case where the solenoid valve 61a for cooling is closed, the controller 7 opens it. On the other hand, in the case where the solenoid valve 61a for cooling is open, the controller 7 maintains this state. In addition, in the case where the solenoid valve 61b for heating is closed, the controller 7 maintains this state, and, in the case where it is open, it is closed. Then, the controller 7 opens the expansion valve 60c (places it in an open state) (S105). For example, in the case where the expansion valve 60c is in a stopped state, the controller 7 opens it. On the other hand, in the case where the expansion valve 60c is open, the controller 7 maintains this state. Note that the controller 7 adjusts the degree of opening of the expansion valve 60c accordingly.
FIG. 3 shows the state in which the injection flow path 6 is open in the cooling mode in this manner. In this case, as shown by white arrows in FIG. 3, part of the liquid-phase refrigerant is diverted from the pipe 41b, passes through the first injection flow path 6a, and is injected through the third injection flow path 6c into the cylinder chamber of the compressor 20 (not shown).
In addition, in S101, in the case where it is determined that the operation mode is not the cooling mode, the controller 7 determines whether or not the operation mode of the chilling unit 1 is the heating mode (S106). In doing so, the controller 7 receives a signal indicating the operation mode from the operation unit 8, for example, and in a case where the received signal is a heating mode selection signal, the operation mode is the heating mode; otherwise, the operation mode is determined as not being the heating mode.
In the case where the operation mode is the heating mode, the controller 7 causes the chilling unit 1 to operate in the heating mode (S107). In this case, the controller 7 operates and controls the four-way valve 21, connects the first port 21a and the third port 21c, connects the second port 21b and the fourth port 21d, and operates the compressor 20.
Next, the controller 7 determines the open flow path enabling/disabling condition (S108). In determining the open flow path enabling/disabling condition, the controller 7 acquires the detected value of the discharge refrigerant temperature Td from the first temperature sensor T1 and compares the acquired value with the reference temperature T0.
In the case where the open flow path enabling/disabling condition is not satisfied (Td ≤ T0), the controller 7 closes the injection flow path 6. In this case, the controller 7 closes the solenoid valve 61a for cooling in the first injection flow path 6a and, also, closes the solenoid valve 61b for heating in the second injection flow path 6b (S104). The controller 7 also places the expansion valve 60c in a stopped state (S104). The control of the controller 7 in this case is the same as in the case where the operation mode is the cooling mode.
In contrast, in the case where the open flow path enabling/disabling condition is satisfied (Td > T0), the controller 7 opens the injection flow path 6. In this case, the controller 7 closes the solenoid valve 61a for cooling in the first injection flow path 6a and opens the solenoid valve 61b for heating in the second injection flow path 6b (S109). For example, in the case where the solenoid valve 61b for heating is closed, the controller 7 opens it. On the other hand, in the case where the solenoid valve 61b for heating is open, the controller 7 maintains this state. In addition, in the case where the solenoid valve 61a for cooling is closed, the controller 7 maintains this state, and, in the case where it is open, it is closed. Furthermore, the controller 7 opens the expansion valve 60c (places it in an open state) (S109). The control of the controller 7 in this case is the same as in the case where the operation mode is the cooling mode. Also in this case, the controller 7 adjusts the degree of opening of the expansion valve 60c accordingly.
FIG. 4 shows the state in which the injection flow path 6 is opened in the heating mode in this manner. In this case, as shown by white arrows in FIG. 4, part of the liquid-phase refrigerant is diverted from the collective pipe 42, passes through the second injection flow path 6b, and is injected through the third injection flow path 6c into the cylinder chamber of the compressor 20 (not shown).
When the injection flow path 6 is closed in S104, the controller 7 determines an operation stop condition of the chilling unit 1 (S110). In addition, when the injection flow path 6 is opened in S105 or S109, the controller 7 determines the operation stop condition of the chilling unit 1 (S110). The operation stop condition is a condition for determining whether or not to stop operation of the chilling unit 1, and is determined according to, for example, whether or not the controller 7 has received a signal indicating the operation stop of the chilling unit 1. The signal indicating the operation stop is transmitted, for example, when the operation stop is selected in the operation unit 8.
In the case where the operation stop condition is not satisfied, the controller 7 determines whether or not the operation mode of the chilling unit 1 is the cooling mode (S101) and selectively repeats the subsequent processes (S102 to S109) according to the determination result.
In contrast, in the case where the operation stop condition is satisfied, the controller 7 stops the operation of the chilling unit 1 (S111).
In other words, while the chilling unit 1 is in operation, a series of open/close control of the injection flow path 6 is repeated. When the operation of the chilling unit 1 is stopped, the series of open/close control of the injection flow path 6 is also ended.
Note that, in S106, in the case where it is determined that the operation mode is not the heating mode, the controller 7 also stops the operation of the chilling unit 1. In this case, it is assumed that the chilling unit 1 is not operating in either the cooling mode or the heating mode (e.g., an error state), and the operation of the chilling unit 1 is stopped in preparation for unforeseen circumstances. At that time, in addition to or instead of stopping operation, the controller 7 may execute a predetermined error process. For example, by turning on (blinking) a warning light, sounding a warning sound, or displaying a warning message, it is possible to make the error state thoroughly known.
Thus, according to the present embodiment, a liquid sealed state in the injection flow path 6 can be avoided. In other words, even when the injection flow path 6 is in a state of being closed, the liquid-phase refrigerant in the injection flow path 6 can flow as follows.
FIG. 5 shows the state in which the injection flow path 6 is closed in this manner. For example, in the case where the injection flow path 6 is opened and then closed, the liquid-phase refrigerant that flows into the injection flow path 6 remains in a target flow path X, as shown in FIG. 5. The target flow path X is a flow path defined in the injection flow path 6 by the check valve 62a for cooling in the first injection flow path 6a, the check valve 62b for heating in the second injection flow path 6b, and the expansion valve 60c in the third injection flow path 6c.
Here, as mentioned above, the expansion valve 60c remains open by the stop opening degree even when it is in a stopped state. Therefore, the liquid-phase refrigerant in the target flow path X becomes a state in which it can flow through the expansion valve 60c toward the cylinder chamber of the compressor 20 (not shown), as shown by white arrows in FIG. 5. In other words, the liquid-phase refrigerant only temporarily stays in the target flow path X and is not blocked in the target flow path X. Therefore, in the case where the injection flow path 6 is opened and then closed, the liquid-phase refrigerant flowing into the injection flow path 6 can avoid becoming a liquid sealed state.
The injection flow path 6 is branched into the first injection flow path 6a, which injects part of the liquid-phase refrigerant into the compressor 20 in the case where the chilling unit 1 is operated in the cooling mode, and a second injection flow path 6b, which injects part of the liquid-phase refrigerant into the compressor 20 in the case where the chilling unit 1 is operated in the heating mode. Therefore, regardless of whether the chilling unit 1 is operated in the cooling mode or the heating mode, the liquid-phase refrigerant in the target flow path X of the injection flow path 6 can avoid becoming the liquid sealed state.
Such avoidance of the liquid sealed state is also made in the same way in a power failure state. In the power failure state, power supply to each element of the chilling unit 1 is cut off. Therefore, in the power failure state, the solenoid valve 61a for cooling and the solenoid valve 61b for heating are closed and the expansion valve 60c becomes the stopped state in the injection flow path 6. Therefore, the liquid-phase refrigerant that flows into the injection flow path 6 may sometimes remain in the target flow path X even in the power failure state. However, even in this case, since the expansion valve 60c maintains a state where it is open by the stop opening degree, the liquid-phase refrigerant that remains in the target flow path X is in a state where it can flow through the expansion valve 60c toward the cylinder chamber of the compressor 20 (not shown), as shown in FIG. 5. Therefore, even in the power failure state, the liquid-phase refrigerant flowing into the injection flow path 6 can avoid being in the liquid sealed state.
In other words, according to the present embodiment, liquid sealing of the liquid-phase refrigerant in the target flow path X can be avoided by simply providing the injection flow path 6, without providing, for example, a bypass flow path to avoid the liquid sealed state in the injection flow path 6. Therefore, liquid sealing of the liquid-phase refrigerant in the target flow path X can be avoided even with relatively simple piping without complicating the piping. In addition, the relatively simple piping makes it possible to save space in the injection flow path 6. In addition, by using the relatively simple piping, it is possible to reduce costs and reduce the risk of refrigerant leakage caused by vibration.
Furthermore, by providing the check valve 62a for cooling in the first injection flow path 6a and the check valve 62b for heating in the second injection flow path 6b, liquid injection operation can be performed by closing one of the solenoid valves 61a and 61b and opening the other. In this case, the check valves 62a and 62b prevent backflow of the liquid-phase refrigerant in the injection flow paths 6a and 6b caused by defective solenoid valves 61a and 61b, etc., making stable liquid injection operation possible and stabilizing the refrigeration cycle operation.
In particular, the solenoid valves 61a and 61b, which are used as two-way valves, may cause reverse flow when pressure opposite to the default forward flow path is applied, depending on the form and quality of the solenoid valve; however, by providing the check valves 62a and 62b on the downstream side of the respective solenoid valves 61a and 61b, respectively, while liquid injection operation is performed in one of the injection flow paths 6a and 6b, backflow caused by the pressure difference generated in the other injection flow path connected in parallel with the one of the flow path can be prevented, thus enabling stable refrigeration cycle operation.
In other words, with respect to forward pressure, the flow is controlled by the solenoid valves 61a and 61b, and, with respect to reverse pressure, the flow is controlled by the check valves 62a and 62b, thus enabling the liquid injection operation and the refrigeration cycle operation to be performed stably. In addition, even in the case of stopping and restarting during liquid injection operation, relatively stable operation can be performed.
Note that, in the above-described embodiment, the refrigeration cycle unit 2 of the chilling unit 1 is configured to include one system of refrigerant circuit R, but multiple systems of refrigerant circuits may be used.
FIG. 6 shows a configuration example of a chilling unit 10 (refrigeration cycle unit 2) comprising four refrigerant systems of refrigerant circuits RA, RB, RC, and RD as another form of the present invention. Each configuration of a first refrigerant circuit RA, a second refrigerant circuit RB, a third refrigerant circuit RC, and a fourth refrigerant circuit RD is equivalent to the refrigerant circuit R described above and comprises elements in common with the refrigerant circuit R, respectively.
In the example shown in FIG. 6, the water heat exchanger 25 comprises a first refrigerant flow path 25a, a second refrigerant flow path 25b, and a water flow path 25c. The first refrigerant flow path 25a of the water heat exchanger 25 is connected to the collective pipe 42 of the first refrigerant circuit RA downstream in cooling mode and upstream in heating mode with respect to the receiver 24. The second refrigerant flow path 25b of the water heat exchanger 25 is connected to the collective pipe 42 of the second refrigerant circuit RB. In other words, the first refrigerant circuit RA and the second refrigerant circuit RB are connected in parallel to one water heat exchanger 25 and share the water heat exchanger 25. Similarly, the third refrigerant circuit RC and the fourth refrigerant circuit RD are connected in parallel to one water heat exchanger 25 and share the water heat exchanger 25. Thus, the refrigeration cycle unit 2 of the chilling unit 10 comprises two water heat exchangers 25.
The water circuit unit 5 comprises a water circulation pump 50 and first to fourth water pipes 51a, 51b, 51c, and 51d as main elements.
The first water pipe 51a connects between a water outlet on the utilization equipment side of the chilling unit 10 and a suction inlet of the water circulation pump 50.
The second water pipe 51b connects between a discharge outlet of the water circulation pump 50 and the water flow path 25c of the water heat exchanger 25 of the first refrigerant circuit RA and the second refrigerant circuit RB. The second water pipe 51b is provided with the third pressure sensor P3 to detect water pressure and the fourth temperature sensor T4 to detect water temperature.
The third water pipe 51c connects between the water flow path 25c of the water heat exchanger 25 of the first refrigerant circuit RA and the second refrigerant circuit RB and the water flow path 25c of the water heat exchanger 25 of the third refrigerant circuit RC and the fourth refrigerant circuit RD in series. The third water pipe 51c is provided with the fifth temperature sensor T5 that detects water temperature.
The fourth water pipe 51d connects between the water flow path 25c of the water heat exchanger 25 of the third refrigerant circuit RC and the fourth refrigerant circuit RD and the water inlet on the utilization equipment side of the chilling unit 10. The fourth water pipe 51d is provided with the fourth pressure sensor P4 to detect water pressure and a sixth temperature sensor T6 to detect water temperature.
In the chilling unit 10 shown in FIG. 6, the controller 7 controls the operation of each element of the refrigeration cycle unit 2 and the water circuit unit 5 to control the operation of the chilling unit 10. The operation unit 8 is wired or wirelessly connected to the controller 7, and performs, for example, start operation of the chilling unit 10, mode selection between the cooling operation and the heating operation, and setting operation of water supply temperature, etc.
In the case where such chilling unit 10 operates in the cooling mode, the four-way valve 21 switches so that the first port 21a of the first to fourth refrigerant circuits RA, RB, RC, and RD is connected to the second port 21b, and the third port 21c is connected to the fourth port 21d, as shown in solid lines in FIG. 6. The subsequent control is the same as when the chilling unit 1 is operated in the cooling mode. In the cooling mode, in this case, the water chilled in the water heat exchanger 25 shared by the first refrigerant circuit RA and the second refrigerant circuit RB are cooled again in the process of passing through the water flow path 25c of the other water heat exchanger 25 shared by the third refrigerant circuit RC and the fourth refrigerant circuit RD, by heat exchange with the gas-liquid two-phase refrigerant flowing through the first refrigerant flow path 25a and the second refrigerant flow path 25b of the other water heat exchanger 25. The chilled water cooled over the two stages is supplied to the utilization equipment side from the fourth water pipe 51d.
On the other hand, in the case where the chilling unit 10 operates in the heating mode, the four-way valve 21 switches so that the first port 21a of the first to fourth refrigerant circuits RA, RB, RC, and RD is connected to the third port 21c, and the second port 21b is connected to the fourth port 21d, as shown in broken lines in FIG. 6. The subsequent control is the same as when the chilling unit 1 is operated in the heating mode. In the heating mode, the water heated in the water heat exchanger 25 shared by the first refrigerant circuit RA and the second refrigerant circuit RB is warmed again in the process of passing through the water flow path 25c of the other water heat exchanger 25 shared by the third refrigerant circuit RC and the fourth refrigerant circuit RD, by heat exchange with the gas-liquid two-phase refrigerant flowing through the first refrigerant flow path 25a and the second refrigerant circuit path 25b of the other water heat exchanger 25. The warm water heated over two stages is supplied from the fourth water pipe 51d to the utilization equipment side.
The first to fourth refrigerant circuits RA, RB, RC, and RD are each provided with the injection flow path 6 (first injection flow path 6a, second injection flow path 6b, and third injection flow path 6c) equivalent to the chilling unit 1. In each injection flow path 6, the solenoid valve 61a for cooling, the check valve 62a for cooling, the solenoid valve 61b for heating, the check valve 62b for heating, and the expansion valve 60c are respectively arranged as in the chilling unit 1.
Therefore, even in the chilling unit 10, liquid sealing of the liquid-phase refrigerant in target flow paths XA, XB, XC, and XD can be avoided by simply providing the injection flow path 6, without providing, for example, a bypass flow path to avoid the liquid sealing state in the injection flow path 6.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Reference Signs List

1, 10...Refrigeration cycle device (air-cooled heat pump chilling unit), 2...Refrigeration cycle unit, 5...Water circuit unit, 6...Bypass flow path (injection flow path), 6a...First injection flow path, 6b...Second injection flow path, 6c...Third injection flow path, 7... Controller, 8...Operation unit, 20...Compressor, 21...Four-way valve, 22...Air heat exchanger unit, 23a, 23b... Expansion valve (first expansion valve), 24...Receiver, 25...Water heat exchanger, 25a, 25b...Refrigerant flow path, 25c...Water flow path, 26...Gas-liquid separator, 27...Main pipe, 28...Discharge pipe, 29a, 29b...Air heat exchanger, 30...Fan, 41a, 41b...Pipe, 42... Collective pipe, 43, 44, 46...Pipe, 47...Solenoid valve, 60c...Expansion valve (second expansion valve), 61a...Solenoid valve (solenoid valve for cooling), 61b...Solenoid valve (solenoid valve for heating), 62a...Check valve (check valve for cooling), 62b...Check valve (check valve for heating), R, RA, RB, RC, RD...Refrigerant circuit, T1...First temperature sensor, X, XA, XB, XC, XD...Target flow path.

Claims

A refrigeration cycle device comprising
a refrigerant circuit in which a refrigerant circulates, configured by including a compressor that discharges a gas-phase refrigerant, a heat source-side heat exchanger, a first expansion valve, a user-side heat exchanger, and an injection flow path that diverts part of a liquid-phase refrigerant and injects it into the compressor, wherein

in the injection flow path, a solenoid valve, a check valve, and a second expansion valve are arranged in order from an upstream side in a flow direction of the liquid-phase refrigerant in the injection flow path, and

the second expansion valve is not fully closed, but is characterized in that it becomes a stopped state at an opening angle greater than fully closed.
The refrigeration cycle device of claim 1,
wherein
the injection flow path is configured by including a first injection flow path and a second injection flow path that branch off the refrigerant circuit respectively, and a third injection flow path where the first injection flow path and the second injection flow path merge,

the first injection flow path branches off from the refrigerant circuit between the heat source-side heat exchanger and the first expansion valve and diverts part of the liquid-phase refrigerant that has passed through the heat source-side heat exchanger during a cooling operation where the heat source-side heat exchanger functions as a condenser and the user-side heat exchanger functions as an evaporator, and

the second injection flow path branches off from the refrigerant circuit between the user-side heat exchanger and the first expansion valve and diverts part of the liquid-phase refrigerant that has passed through the user-side heat exchanger during a heating operation where the heat source-side heat exchanger functions as an evaporator and the user-side heat exchanger functions as a condenser.
The refrigeration cycle device of claim 2,
wherein
in the first injection flow path, a solenoid valve for cooling and a check valve for cooling are arranged in order from an upstream side in a flow direction of the liquid-phase refrigerant in the first injection flow path,

in the second injection flow path, a solenoid valve for heating and a check valve for heating are arranged in order from an upstream side in a flow direction of the liquid-phase refrigerant in the second injection flow path, and

in the third injection flow path, the second expansion valve is arranged.
The refrigeration cycle device of claim 3, further comprising:
a detector for detecting a temperature of the gas-phase refrigerant discharged from the compressor; and

a controller for controlling operations of the compressor, the first expansion valve, the solenoid valve, and the second expansion valve, wherein

the controller,

during the cooling operation, in a case where a temperature of the gas-phase refrigerant detected by the detector exceeds a predetermined temperature, opens the solenoid valve for cooling, closes the solenoid valve for heating, and opens the second expansion valve,

during the heating operation, in a case where a temperature of the gas-phase refrigerant detected by the detector exceeds a predetermined temperature, closes the solenoid valve for cooling, opens the solenoid valve for heating, and opens the second expansion valve, and

during the cooling operation and the heating operation, in a case where a temperature of the gas-phase refrigerant detected by the detector is a predetermined temperature or lower, closes the solenoid valve for cooling, closes the solenoid valve for heating, and places the second expansion valve in the stopped state.