Refrigeration equipment

Abstract

To suppress degradation of user's comfort in taking a measure for impact noise of a switching mechanism.SOLUTION: A refrigeration device 1 includes: a refrigerant circuit 4 which has a compressor 11, a heat source-side heat exchanger 12, a pressure reduction mechanism 13 and a use-side heat exchanger 14 and in which a refrigerant is circulated; a switching mechanism 15 disposed in the refrigerant circuit 4 and switched to a first state in which the refrigerant discharged from the compressor 11 is conveyed to the heat source-side heat exchanger 12 and a second state in which the refrigerant discharged from the compressor 11 is conveyed to the use-side heat exchanger 14; a detecting portion 21 for detecting a temperature of a room R1 in which the use-side heat exchanger 14 is disposed; and a control portion 5 for controlling the compressor 11 and the switching mechanism 15. The control portion 5 controls a frequency of the compressor 11 to a prescribed value or less in a first time before switching from the first state to the second state, and the control portion 5 determines the first time on the basis of change of a detection temperature of the detecting portion 21 during a time when the switching mechanism 15 is in the first state.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there has been known a refrigeration system that can be switched between heating operation and cooling operation by switching the flow of the refrigerant circuit with a switching mechanism such as a four-way switching valve. Some of these refrigeration systems, such as those disclosed in Patent Document 1, perform a defrosting operation to remove frost that has adhered to an outdoor heat exchanger by performing the same refrigeration cycle as the cooling operation.

[0003] It is known that when the switching mechanism is switched when the pressure difference between the ports is large, high pressure acts on the port that was previously at low pressure, generating impact noise.Patent Document 1 discloses a technology for reducing the pressure difference between the ports by providing a pressure equalization time during which the operating frequency of the compressor is lowered before switching the switching mechanism in order to suppress the impact noise generated by the switching mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 030076 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of suppressing the impact noise of the switching mechanism, it is preferable to make the pressure equalization time longer. On the other hand, since heating operation is not performed during the pressure equalization time, if the pressure equalization time is long, the room temperature may drop, which may worsen the comfort of the user.

[0006] The present disclosure aims to suppress deterioration of user comfort when taking measures against impact noise of a switching mechanism. [Means for solving the problem]

[0007] (1) A refrigeration device disclosed herein includes a refrigeration circuit having a compressor, a heat source side heat exchanger, a pressure reducing mechanism, and a utilization side heat exchanger, and through which a refrigerant circulates; a switching mechanism provided in the refrigerant circuit, which switches between a first state in which the refrigerant discharged from the compressor is sent to the heat source side heat exchanger and a second state in which the refrigerant discharged from the compressor is sent to the utilization side heat exchanger; a detection unit which detects the temperature of a room in which the utilization side heat exchanger is provided; and a control unit which controls the compressor and the switching mechanism, wherein the control unit sets the frequency of the compressor to a predetermined value or lower for a first time before switching from the first state to the second state, and the control unit determines the first time based on a change in the detected temperature of the detection unit while the switching mechanism is in the first state.

[0008] With this configuration, the first time for pressure equalization can be determined taking into account the temperature change in the room while in the first state (i.e., defrost operation), thereby preventing a decrease in user comfort when taking measures against the impact noise of the switching mechanism.

[0009] (2) Preferably, the control unit shortens the first time period when the detected temperature decreases more rapidly than a first rate of change.

[0010] According to this configuration, when the temperature in the room drops rapidly, the first time period for performing pressure equalization is shortened, thereby making it possible to suppress deterioration of user comfort due to the drop in room temperature.

[0011] (3) Preferably, the control unit extends the first time period when the detected temperature decreases more slowly than the first rate of change.

[0012] According to this configuration, when the temperature in the room drops slowly, the first time period for performing pressure equalization is extended, so that the impact noise of the switching mechanism can be more reliably suppressed.

[0013] (4) Preferably, the control unit calculates a rate of change of the detected temperature each time the switching mechanism is switched to the first state, and determines the first rate of change based on a plurality of calculated rates of change.

[0014] According to this configuration, the first change rate that serves as a reference can be determined for each room based on the temperature change rates of multiple past times.

[0015] (5) Preferably, the control unit calculates a change in the detected temperature while the switching mechanism is in the first state, and the control unit determines, based on the calculated change in the detected temperature, the time to switch from the first state at which the change in the detected temperature was calculated to the second state.

[0016] According to this configuration, it is possible to shorten or extend the end time of the pressure equalization control executed in the first state in which the change in the detected temperature is calculated. This allows the first time to be changed immediately in consideration of the change in the room temperature, so that it is possible to more reliably prevent the deterioration of user comfort due to a drop in the room temperature.

[0017] (6) Preferably, the control unit calculates a change in the detected temperature while the switching mechanism is in the first state, and based on the calculated change in the detected temperature, the control unit determines the first time after the switching mechanism has been switched to the second state one or more times from the first state in which the change in the detected temperature was calculated.

[0018] According to this configuration, the calculated change in the detected temperature can be reflected in the first hour from the next time onwards, so that it is possible to more reliably prevent the deterioration of user comfort due to a drop in room temperature.

[0019] (7) Preferably, the control unit determines the first time period based on a model of an indoor unit that accommodates the utilization side heat exchanger.

[0020] According to this configuration, the first time period for performing pressure equalization can be determined taking into consideration the model of the indoor unit, so that the impact noise of the switching mechanism can be more reliably suppressed.

[0021] (8) Preferably, the control unit extends the first time period as the volume of the indoor unit increases.

[0022] The larger the volume of the indoor unit, the more difficult it is to reduce the pressure difference in the switching mechanism, and a relatively long pressure equalization time is required. In such cases, the first time can be extended, so the impact noise of the switching mechanism can be more reliably suppressed. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram showing a configuration of a refrigeration device according to an embodiment; [Diagram 2] FIG. 2 is a functional block diagram of the refrigeration device according to the embodiment. [Diagram 3] FIG. 4 is a diagram illustrating the internal structure of the switching mechanism in a first state. [Figure 4] 11 is a diagram illustrating the internal structure of the switching mechanism in a second state. FIG. [Diagram 5] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 6] 4 is a flowchart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 7] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0025] [Embodiment] [Refrigeration system configuration] FIG. 1 is a diagram illustrating a schematic configuration of a refrigeration device 1 according to an embodiment. FIG. 2 is a functional block diagram of the refrigeration device 1 according to the embodiment. The configuration of the refrigeration device 1 will be described below with reference to FIGS.

[0026] The refrigeration device 1 functions as an air conditioner that conditions the air in a room R1, and includes an indoor unit 2 installed in the room R1, an outdoor unit 3 installed outdoors, a refrigerant circuit 4 through which a refrigerant circulates, and a control unit 5. The refrigerant is, for example, R32.

[0027] The refrigerant circuit 4 has a compressor 11, a heat source side heat exchanger 12, a pressure reducing mechanism 13, a utilization side heat exchanger 14, a switching mechanism 15, an accumulator 16, and piping 41 connecting these respective parts 11 to 16. The piping 41 connects the respective parts 11 to 16 so that when the heat source side heat exchanger 12 functions as a condenser (i.e., when the refrigeration device 1 performs cooling operation), the refrigerant discharged from the compressor 11 flows through the switching mechanism 15, the heat source side heat exchanger 12, the pressure reducing mechanism 13, the utilization side heat exchanger 14, the switching mechanism 15, and the accumulator 16 in this order, and returns to the compressor 11.

[0028] The control unit 5 has an indoor control unit 5a and an outdoor control unit 5b connected to each other by a communication line. As shown in Fig. 2, the indoor control unit 5a has a processor 52a and a memory 53a. The indoor control unit 5a controls the indoor unit 2 by the processor 52a performing various calculations and control based on the programs contained in the memory 53a. The outdoor control unit 5b has a processor 52b and a memory 53b. The outdoor control unit 5b controls the outdoor unit 3 by the processor 52b performing various calculations and control based on the programs contained in the memory 53b.

[0029] The indoor unit 2 houses the utilization side heat exchanger 14 and part of the piping 41 of the refrigerant circuit 4. The indoor unit 2 further houses the detection unit 21, the indoor control unit 5a, and an indoor fan 61. The utilization side heat exchanger 14 is, for example, a cross fin tube type heat exchanger. The indoor fan 61 is, for example, a cross flow fan. When the indoor fan 61 operates, air in the room R1 is sucked in from an intake port (not shown) of the indoor unit 2, and the conditioned air that has exchanged heat with the refrigerant in the utilization side heat exchanger 14 is supplied into the room R1 from an exhaust port (not shown) of the indoor unit 2.

[0030] The detection unit 21 is, for example, a temperature sensor that is installed near the air inlet of the indoor unit 2 and detects the temperature of the air in room R1. The detection unit 21 is electrically connected to the indoor control unit 5a and outputs a detection signal to the indoor control unit 5a.

[0031] A remote control unit 51 (hereinafter referred to as "remote control 51") is attached to the indoor unit 2. The remote control 51 is provided in the room R1 in a state capable of communicating with the indoor control unit 5a via wired or wireless communication, and transmits control signals to the indoor control unit 5a in response to user operations.

[0032] The remote control 51 is further provided with a detection unit 22. The detection unit 22 is a temperature sensor that detects the temperature of the air in the room R1. The detection unit 22 may be installed, for example, in a location in the room R1 that is frequently used by the user (such as a work space), or may be built into the remote control 51. The detection unit 22 is connected to the remote control 51 by wire or wirelessly, and transmits a detection signal to the indoor control unit 5a via the remote control 51.

[0033] 2, the remote control 51 includes an operation switch 71, an operation changeover switch 72, and a temperature setting switch 73. Each time the operation switch 71 is operated, it switches between operation and stop of the refrigeration device 1. Each time the operation changeover switch 72 is operated, it switches the operation mode of the refrigeration device 1 alternately between a cooling operation mode and a heating operation mode. The temperature setting switch 73 includes an up button and a down button, and each time the up button is operated, the set temperature increases, and each time the down button is operated, the set temperature decreases.

[0034] The outdoor unit 3 accommodates the compressor 11, the heat source side heat exchanger 12, the pressure reducing mechanism 13, the switching mechanism 15, and the accumulator 16 of the refrigerant circuit 4, as well as part of the piping 41. The outdoor unit 3 further accommodates an outdoor control unit 5b and an outdoor fan 62.

[0035] The compressor 11 is, for example, a variable capacity compressor, and its rotation frequency (hereinafter simply referred to as "frequency") is controlled by an inverter based on an operation command from the control unit 5. The heat source side heat exchanger 12 is, for example, a cross fin tube type heat exchanger. The pressure reducing mechanism 13 is, for example, a solenoid valve (expansion valve), and adjusts the pressure and flow rate of the refrigerant flowing through the piping 41. The accumulator 16 is a device that separates the refrigerant into gas and liquid to protect the compressor 11.

[0036] The switching mechanism 15 is a valve, such as a four-way switching valve, that switches the flow direction of the refrigerant in the pipe 41. The switching mechanism 15 has four ports P1 to P4 that are respectively connected to the regions 41a to 41d of the pipe 41. The switching mechanism 15 is controlled by the controller 5 to be switched between a first state (solid line in FIG. 1) and a second state (dashed line in FIG. 1).

[0037] In the first state, port P1 and port P4 communicate with each other, and port P2 and port P3 communicate with each other. In the first state, the refrigerant discharged from the compressor 11 to the region 41a is sent to the heat source side heat exchanger 12 through the region 41d. In the second state, port P1 and port P2 communicate with each other, and port P3 and port P4 communicate with each other. In the second state, the refrigerant discharged from the compressor 11 to the region 41a is sent to the utilization side heat exchanger 14 through the region 41b. The internal structure of the switching mechanism 15 will be described later.

[0038] The outdoor fan 62 is, for example, a propeller fan. When the outdoor fan 62 operates, outdoor air is sucked in from an intake port (not shown) of the outdoor unit 3, and the air that has exchanged heat with the refrigerant in the heat source side heat exchanger 12 is discharged from an exhaust port (not shown) of the outdoor unit 3 to the outdoor space.

[0039] [About driving modes] The operation modes of the refrigeration device 1 include a cooling operation mode and a heating operation mode. Based on an instruction received by the remote control 51, the control unit 5 executes the cooling operation mode or the heating operation mode.

[0040] In the cooling operation mode, the refrigeration device 1 performs cooling operation. In the cooling operation, the control unit 5 sets the switching mechanism 15 to the first state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as a condenser and the utilization side heat exchanger 14 serves as an evaporator.

[0041] The high-pressure refrigerant discharged from the compressor 11 passes through the region 41a, ports P1 and P4 of the switching mechanism 15, and region 41d, and enters the heat source side heat exchanger 12, where it exchanges heat with the outdoor air and condenses. The condensed refrigerant is depressurized when it passes through the pressure reducing mechanism 13, passes through region 41e, and enters the utilization side heat exchanger 14, where it exchanges heat with the air in room R1 and evaporates. The conditioned air cooled by the refrigerant is blown into room R1 by the indoor fan 61. The refrigerant that leaves the utilization side heat exchanger 14 passes through region 41b, ports P2 and P3 of the switching mechanism 15, and region 41c, and enters the accumulator 16, where gas-liquid separation occurs, and then the refrigerant is sucked into the compressor 11.

[0042] In the heating operation mode, the refrigeration device 1 alternates between the heating operation and the defrost operation. In the heating operation, the control unit 5 sets the switching mechanism 15 to the second state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as an evaporator and the utilization side heat exchanger 14 serves as a condenser.

[0043] The high-pressure refrigerant discharged from the compressor 11 passes through the region 41a, ports P1 and P2 of the switching mechanism 15, and region 41b, and enters the utilization side heat exchanger 14, where it exchanges heat with the air in the room R1 and condenses. The conditioned air heated by the refrigerant is blown into the room R1 by the indoor fan 61. The condensed refrigerant is depressurized when it passes through the decompression mechanism 13, passes through region 41e, and enters the heat source side heat exchanger 12, where it exchanges heat with the outdoor air and evaporates. The refrigerant that leaves the heat source side heat exchanger 12 passes through region 41d, ports P4 and P3 of the switching mechanism 15, and region 41c, and enters the accumulator 16, where gas-liquid separation occurs, and then the refrigerant is drawn into the compressor 11.

[0044] When a predetermined defrost start condition is satisfied during heating operation, the control unit 5 lowers the frequency of the compressor 11 to perform pressure equalization control described below, and then starts defrost operation. The defrost operation is an operation for melting frost adhering to the heat source side heat exchanger 12. The defrost start condition is, for example, that a predetermined time has elapsed since the start of heating operation. The predetermined time may be set to a constant value in advance, or may be appropriately set by the control unit 5 according to the difference between the temperature of the refrigerant flowing through the heat source side heat exchanger 12 and the outside air temperature.

[0045] In the defrost operation, the control unit 5 sets the switching mechanism 15 to the first state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as a condenser and the utilization side heat exchanger 14 serves as an evaporator. This causes the heat of the refrigerant to be released in the heat source side heat exchanger 12, and the frost adhering to the heat source side heat exchanger 12 melts.

[0046] When a predetermined defrost end condition is satisfied during the defrost operation, the control unit 5 lowers the frequency of the compressor 11 to perform pressure equalization control described below, and then starts the heating operation. The defrost end condition is, for example, that a predetermined time has elapsed since the start of the defrost operation. The predetermined time may be set to a constant value in advance, or may be appropriately set by the control unit 5 according to the difference between the temperature of the refrigerant flowing through the heat source side heat exchanger 12 and the outside air temperature.

[0047] [Internal structure of the switching mechanism] FIG. 3 is a diagram illustrating the internal structure of the switching mechanism 15 in the first state. FIG. 4 is a diagram illustrating the internal structure of the switching mechanism 15 in the second state.

[0048] The internal structure of the switching mechanism 15 will be described with reference to Figures 3 and 4. In Figures 3 and 4, cross-sectional areas are hatched. "LP" in Figures 3 and 4 indicates a region where the suction pressure (low pressure) of the refrigerant in the compressor 11 acts, and "HP" indicates a region where the discharge pressure (high pressure) of the refrigerant in the compressor 11 acts.

[0049] The switching mechanism 15 has a main body portion 8 and a pilot solenoid valve 9 . The main body 8 has a housing 81, a valve body 82, partition plates 83 and 84, a support plate 85, and connection pipes 86 to 89. Four ports P1 to P4 are formed in the housing 81. The valve body 82, the partition plates 83 and 84, and the support plate 85 are housed in the housing 81 in a slidable state.

[0050] The valve body 82 is provided so as to separate a space on the port P1 side from a space on the port P3 side within the housing 81. Partition plates 83 and 84 are plates that separate the inside of the housing 81. The partition plate 83 and the housing 81 form a first chamber S1, and the partition plate 84 and the housing 81 form a second chamber S2.

[0051] The support plate 85 is a plate that transmits the force that moves the partition plates 83 and 84 to the valve body 82. One end of the support plate 85 is connected to the partition plate 83, the other end of the support plate 85 is connected to the partition plate 84, and the central portion of the support plate 85 is connected to the valve body 82. The support plate 85 is formed with a through hole 85a for passing the refrigerant from the port P1 to the port P4, and a through hole 85b for passing the refrigerant from the port P1 to the port P2.

[0052] The connecting pipe 86 is provided on the port P1 side and supplies the pressure (high pressure) acting on the port P1 to the pilot solenoid valve 9. The connecting pipe 87 is provided on the port P3 side and supplies the pressure (low pressure) acting on the port P3 to the pilot solenoid valve 9. The connecting pipe 88 is provided in the first chamber S1 and the pressure supplied from the connecting pipe 86 or the connecting pipe 87 is applied via the pilot solenoid valve 9. The connecting pipe 89 is provided in the second chamber S2 and the pressure supplied from the connecting pipe 86 or the connecting pipe 87 is applied via the pilot solenoid valve 9.

[0053] The pilot solenoid valve 9 has a port 91 communicating with a connecting pipe 86, a port 92 communicating with a connecting pipe 87, a port 93 communicating with a connecting pipe 88, a port 94 communicating with a connecting pipe 89, a valve body (not shown), and a coil mechanism (not shown). The valve body is biased to a position where the port 91 and the port 94 communicate with each other. The coil mechanism receives power from an external power source to generate an electromagnetic force, and the electromagnetic force moves the valve body to a position where the port 91 and the port 93 communicate with each other.

[0054] The control unit 5 controls the voltage applied to the coil mechanism of the pilot solenoid valve 9. When the switching mechanism 15 is in the first state, the control unit 5 does not apply a voltage to the coil mechanism. As a result, the port 91 and the port 94 communicate with each other, and the high pressure drawn from the connecting pipe 86 acts on the second chamber S2 via the connecting pipe 89. At this time, the port 92 and the port 93 communicate with each other, and the low pressure drawn from the connecting pipe 87 acts on the first chamber S1 via the connecting pipe 88.

[0055] When low pressure acts on the first chamber S1 and high pressure acts on the second chamber S2, the partition plate 83 moves in the direction that narrows the first chamber S1, and the partition plate 84 moves in the direction that widens the second chamber S2. The force that moves the partition plates 83 and 84 is transmitted to the valve body 82 via the support plate 85, and the valve body 82 moves to a position (first position) that covers the ports P2 and P3 as shown in Figure 3. This results in a first state in which the ports P1 and P4 communicate with each other, and the ports P2 and P3 communicate with each other. In the first state, high pressure acts on the ports P1 and P4, and low pressure acts on the ports P2 and P3.

[0056] When the control unit 5 sets the switching mechanism 15 to the second state, it applies a voltage to the coil mechanism. This causes port 91 to communicate with port 93, and the high pressure drawn from the connecting pipe 86 acts on the first chamber S1 via the connecting pipe 88. At this time, port 92 and port 94 communicate with each other, and the low pressure drawn from the connecting pipe 87 acts on the second chamber S2 via the connecting pipe 89.

[0057] When high pressure acts on the first chamber S1 and low pressure acts on the second chamber S2, the partition plate 83 moves in the direction in which the first chamber S1 becomes wider, and the partition plate 84 moves in the direction in which the second chamber S2 becomes narrower. As a result, the valve body 82 moves to a position (second position) covering the ports P3 and P4 as shown in Fig. 4. This results in a second state in which the ports P1 and P2 communicate with each other, and the ports P3 and P4 communicate with each other. In the second state, high pressure acts on the ports P1 and P2, and low pressure acts on the ports P3 and P4.

[0058] [About impact noise] For example, during defrost operation, the switching mechanism 15 is in the first state (Fig. 3) and low pressure is applied to port P2. When the operation shifts from defrost operation to heating operation, the switching mechanism 15 is switched to the second state (Fig. 4) by an operation command from the control unit 5, and high pressure from port P1 is applied to port P2, which had been subjected to low pressure until then, and an impact noise is generated due to the pressure change.

[0059] Similarly, when switching from heating operation to defrost operation, high pressure from port P1 acts on port P4, which had previously been under low pressure, and an impact noise is generated due to the pressure change.

[0060] [About pressure equalization control] In order to suppress the impact noise of the switching mechanism 15, the control unit 5 performs pressure equalization control to lower the frequency of the compressor 11 to a predetermined value or less before switching the switching mechanism 15. This reduces the pressure difference between the port P1 and the port P2 (or the port P4), thereby suppressing the impact noise caused by the pressure change. Therefore, in order to suppress the impact noise, it is preferable to extend the pressure equalization time (hereinafter referred to as the "first time") for performing the pressure equalization control.

[0061] On the other hand, since the room R1 is not heated during the defrost operation, if the first time period in the defrost operation is extended, the temperature of the room R1 may decrease, which may cause a decrease in the comfort of the user.

[0062] Here, the speed at which the temperature of room R1 drops depends on the characteristics of room R1 (e.g., insulation performance, volume) and the outside air temperature. If the temperature of room R1 drops slowly, there is a grace period before the temperature drops to a level at which the user feels cold, so it is preferable to lengthen the first time period to suppress the impact noise generated by switching mechanism 15. If the temperature of room R1 drops rapidly, there is no grace period before the temperature drops to a level at which the user feels cold, so it is preferable to shorten the first time period to resume heating operation early.

[0063] The control unit 5 of the refrigeration device 1 determines the first time based on a change in the temperature detected by the detection unit 21 during the defrost operation. Specifically, the control unit 5 shortens the first time when the temperature detected by the detection unit 21 during the defrost operation decreases more rapidly than a predetermined first rate of change, and extends the first time when the temperature detected by the detection unit 21 during the defrost operation decreases more slowly than the predetermined first rate of change.

[0064] This makes it possible to take measures against impact noise from the switching mechanism 15 by setting the first time, while at the same time preventing the user's comfort from deteriorating by shortening the first time when the temperature of the room R1 drops suddenly.

[0065] A specific example of control of the refrigeration device 1 will now be described.

[0066] [Refrigeration device control example 1] FIG. 5 is a time chart illustrating a first control example of the refrigeration device 1. As shown in FIG. FIG. 6 is a flowchart illustrating a first control example of the refrigeration device 1. When the heating operation mode is instructed on the remote control 51, the refrigeration device 1 starts the heating operation. Fig. 5 mainly shows the nth defrost operation (from time t2 to time t4) and the (n+1)th defrost operation (from time t5 to time t7) after the heating operation mode is instructed.

[0067] In the first control example, the control unit 5 determines the first time X2 in the (n+1)th defrost operation based on the temperature change in the room R1 in the nth defrost operation. The details of this will be described below.

[0068] [Switching from heating operation to defrost operation for the nth time] 5, in the heating operation, the control unit 5 puts the switching mechanism 15 in the second state (FIG. 4) and rotates the compressor 11 at the frequency F2. This heats the room R1 so that the temperature detected by the detection unit 21 is maintained at the set temperature Th1.

[0069] During heating operation, when the defrost start condition described above is satisfied, first the control unit 5 reduces the frequency of the compressor 11 from F2 to a predetermined frequency F1 (an example of a predetermined value) for pressure equalization. After the frequency of the compressor 11 becomes F1 at time t1, the control unit 5 performs pressure equalization of the switching mechanism 15 by rotating the compressor 11 at the frequency F1 until time t2. Note that the frequency F1 may be "0". In this case, when the defrost start condition is satisfied, the control unit 5 performs pressure equalization of the switching mechanism 15 by stopping the compressor 11.

[0070] Next, at time t2, the control unit 5 switches the switching mechanism 15 from the second state to the first state, and increases the frequency of the compressor 11 to a target value of F2. As a result, the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the heat source side heat exchanger 12, and the defrost operation is started.

[0071] In this control example, the frequency during normal operation of the compressor 11 in both the heating operation and the defrost operation (the frequency on the upper side of FIG. 5) is described as F2, but the frequency during normal operation of the compressor 11 may be a value other than F2 as long as it is greater than F1, and is not particularly limited. In the second control example (FIG. 7) described later, the frequency during normal operation is also described as F2 for simplicity.

[0072] During the defrost operation, the detector 21 continues to detect the temperature of the room R1. Since the refrigeration device 1 does not heat the room R1 during the defrost operation, the detected temperature gradually decreases from Th1 after time t2 as shown in FIG.

[0073] [Switching from defrost operation to heating operation for the nth time] When the above-mentioned defrost end condition is satisfied during the defrost operation, the control unit 5 reduces the frequency of the compressor 11 from F2 to frequency F1. After the frequency of the compressor 11 becomes F1 at time t3, the control unit 5 rotates the compressor 11 at frequency F1 until time t4, thereby performing pressure equalization of the switching mechanism 15. The time X1 from time t3 to time t4 is the pressure equalization time in the nth defrost operation.

[0074] Next, at time t4, the control unit 5 switches the switching mechanism 15 from the first state to the second state, and increases the frequency of the compressor 11 to a target value of F2. As a result, the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the utilization-side heat exchanger 14, and heating operation is started.

[0075] After the heating operation is started at time t4, the temperature of room R1 continues to decrease until the heating rate of room R1 exceeds the cooling rate of room R1. Therefore, a minimum value Tp1 appears in the detected temperature between time t4 and time t5.

[0076] Next, a flow of determining the pressure equalization time by the control unit 5 will be described with reference to FIG. The control unit 5 calculates the change in the detected temperature of the detection unit 21 during the nth defrost operation, for example, between time t4 and time t5. Specifically, the control unit 5 obtains the detected temperature at predetermined times (for example, every 5 seconds) during the nth defrost operation (while the switching mechanism 15 is in the first state), and calculates an approximation line of the obtained detected temperatures by the least squares method or the like. Then, the change rate dT1 (slope) of the approximation line is obtained as the change in the detected temperature of the detection unit 21 (step ST1).

[0077] The change in the temperature detected by the detector 21 may be the rate of change of temperature as described above, or may be the amount of change of temperature. When the amount of change is used as the change in the temperature detected by the detector 21, for example, the amount of change may be the difference between the detected temperature Th1 at the start of the defrost operation (time t2) and the detected temperature at the end of the defrost operation (time t4), or the difference between the detected temperature Th1 and the minimum value Tp1.

[0078] Next, the control unit 5 compares the first rate of change dTa, which is a reference, with the calculated rate of change dT1 (step ST2). When the amount of change in temperature is used as the change in the detected temperature, the control unit 5 compares the first amount of change, which is a reference, with the calculated amount of change.

[0079] Here, the first rate of change dTa may be a predetermined value set in advance, or may be a value calculated according to the rate of change of temperature in past defrost operations. For example, each time the switching mechanism 15 is switched to the first state, the control unit 5 calculates the rate of change of the detected temperature, and determines the first rate of change dTa based on the plurality of calculated rates of change.

[0080] Specifically, the control unit 5 calculates the rate of change of temperature for (m - 1) times during the defrost operation from the (n - m)-th time to the (n - 1)-th time. Then, the average value of these plurality of rates of change is obtained as the first rate of change dTa. Thereby, the first rate of change dTa, which is the average rate of change of temperature in the defrost operation before the (n - 1)-th time, can be determined according to the room R1.

[0081] As a result of the control unit 5 comparing the first rate of change dTa and the rate of change dT1, as shown in FIG. 5, when the rate of change dT1 is smaller than the first rate of change dTa (dT1 < dTa: the temperature of the room R1 decreases more rapidly than the reference), the control unit 5 determines the first time (equalizing time) in the (n + 1)-th defrost operation to be a time X2 shorter than the time X1 (step ST3).

[0082] As a result of the control unit 5 comparing the first rate of change dTa and the rate of change dT1, when the rate of change dT1 is larger than the first rate of change dTa (dT1 > dTa: the temperature of the room R1 decreases more gently than the reference), the control unit 5 determines the first time (equalizing time) in the (n + 1)-th defrost operation to be a time X3 longer than the time X1 (step ST4).

[0083] As a result of the control unit 5 comparing the first rate of change dTa and the rate of change dT1, when the rate of change dT1 is equal to the first rate of change dTa (dT1 = dTa: the temperature of the room R1 decreases in the same manner as the reference), the control unit 5 determines the first time (equalizing time) in the (n + 1)-th defrost operation to be the time X1 without shortening or extending it (step ST5).

[0084] The first rate of change may be a value having a predetermined range. For example, the first rate of change may be (dTa±α). In this case, the control unit 5 may shorten the first time to be shorter than the time X1 when the rate of change dT1 is smaller than the lower limit value (dTa-α) of the first rate of change, extend the first time to be longer than the time X1 when the rate of change dT1 is larger than the upper limit value (dTa+α) of the first rate of change, and set the first time to be the time X1 when the rate of change dT1 is equal to or larger than the lower limit value (dTa-α) of the first rate of change and equal to or smaller than the upper limit value (dTa+α).

[0085] [Switching from heating operation to defrost operation for the (n+1)th time] After time t4, the heating operation is started, and the temperature detected by the detector 21 rises again to the set temperature Th1. Thereafter, when the defrost start condition is satisfied, the controller 5 reduces the frequency of the compressor 11 from F2 to F1 and performs pressure equalization for a predetermined time, similar to the control up to time t2 described above. Then, at time t5, the controller 5 switches the switching mechanism 15 from the second state to the first state, and increases the frequency of the compressor 11 to a target value of F2, thereby starting the (n+1)th defrost operation.

[0086] [(n+1)th switch from defrost operation to heating operation] When the above-mentioned defrost end condition is satisfied during the defrost operation, the control unit 5 reduces the frequency of the compressor 11 from F2 to frequency F1. After the frequency of the compressor 11 becomes F1 at time t6, the control unit 5 performs pressure equalization of the switching mechanism 15 by rotating the compressor 11 at frequency F1 until time t7.

[0087] Here, the first time X2 from time t6 to time t7 is the pressure equalization time in the (n+1)th defrost operation, and is a value determined by the control unit 5 as described above based on the temperature change in the nth defrost operation.

[0088] Next, at time t7, the control unit 5 switches the switching mechanism 15 from the first state to the second state, and increases the frequency of the compressor 11 to a target value of F2. As a result, the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the utilization-side heat exchanger 14, and heating operation is started.

[0089] After the heating operation is started at time t7, the temperature of room R1 continues to decrease until the heating rate of room R1 exceeds the cooling rate of room R1. For this reason, the detected temperature reaches a minimum value Tp2 after time t7.

[0090] As described above, when the detected temperature in the nth defrost operation decreases more rapidly than the first rate of change dTa, the control unit 5 shortens the first time X2 of the (n+1)th defrost operation to be shorter than the first time X1 of the nth defrost operation. In this way, while the temperature of the room R1 drops to the minimum value Tp1 in the nth defrost operation, the temperature of the room R1 can be kept at the minimum value Tp2 higher than Tp1 by shortening the first time X2 in the (n+1)th defrost operation. As a result, it is possible to suppress deterioration of the user's comfort due to a drop in the temperature of the room R1.

[0091] When the detected temperature decreases more slowly than the first rate of change dTa in the nth defrost operation, the control unit 5 extends the first time X3 of the (n+1)th defrost operation beyond the first time X1 of the nth defrost operation. Since the temperature drop in the room R1 is more gradual than the reference, extending the first time X3 for pressure equalization has little effect on the comfort of the user. By extending the first time X3, the impact noise of the switching mechanism 15 can be more reliably suppressed. As a result, deterioration of the comfort of the user due to the impact noise of the switching mechanism 15 can be suppressed.

[0092] [Refrigeration device control example 2] Fig. 7 is a time chart for explaining a second control example of the refrigeration device 1. Fig. 7 mainly shows the n-th defrost operation (from time t2 to time t4a) after the heating operation mode is instructed.

[0093] In the second control example, the control unit 5 determines the first time X1a (pressure equalization time) in the n-th defrost operation based on the temperature change in the room R1 in the n-th defrost operation. The details of this will be described below.

[0094] [Switching from defrost operation to heating operation for the nth time] In the second control example, the compressor 11 and the switching mechanism 15 are controlled in the same manner as in the first control example until time t3. In the n-th defrost operation, the control unit 5 calculates the change in the detected temperature of the detection unit 21 in real time. For example, at time t3, the control unit 5 calculates the rate of change dT1 based on the detected temperatures obtained from time t2 to time t3.

[0095] Then, at time t3, the control unit 5 compares the first rate of change dTa with the rate of change dT1. If the rate of change dT1 is equal to the first rate of change dTa (dTa=dT1), the control unit 5 sets the first time in the n-th defrost operation to time X1, and ends the pressure equalization control that started at time t3 at time t4. As shown by the phantom line in FIG. 7, at time t4, the control unit 5 switches the switching mechanism 15 from the first state to the second state, and increases the frequency of the compressor 11 with F2 as the target value. This causes the control unit 5 to start the heating operation.

[0096] The first time X1 and time t4 are the pressure equalization time and its end time that are adopted when the calculated rate of change dT1 is equal to the reference first rate of change dTa. In the following description of the second control example, the first time X1 and time t4 are appropriately referred to as the "first scheduled time X1" and the "scheduled end time t4", respectively.

[0097] As shown by the solid line in FIG. 7, when the rate of change dT1 is smaller than the first rate of change dTa (dTa > dT1: the temperature of room R1 decreases rapidly from the reference), the control unit 5 determines the first time in the n-th defrost operation to be a time X1a shorter than the first scheduled time X1. Specifically, the control unit 5 determines the time (the end time of the pressure equalization time) when switching the switching mechanism 15 from the first state to the second state in the n-th defrost operation to be a time t4a earlier than the scheduled end time t4.

[0098] Note that when the rate of change dT1 is larger than the first rate of change dTa (dTa < dT1: the temperature of room R1 decreases gently from the reference), the control unit 5 determines the first time in the n-th defrost operation to be a time X1b (not shown) extended from the first scheduled time X1. Specifically, the control unit 5 determines the time when switching the switching mechanism 15 from the first state to the second state in the n-th defrost operation to be a time t4b (not shown) later than the scheduled end time t4.

[0099] During the defrost operation, when the aforementioned defrost end condition is satisfied, the control unit 5 decreases the frequency of the compressor 11 from F2 to F1. After the frequency of the compressor 11 reaches F1 at time t3, in the case of FIG. 7 (the case of dTa > dT1), the control unit 5 rotates the compressor 11 at the frequency F1 until the above time t4a to perform pressure equalization of the switching mechanism 15. The time X1a from time t3 to time t4a is the pressure equalization time in the n-th defrost operation.

[0100] Subsequently, the control unit 5 switches the switching mechanism 15 from the first state to the second state at time t4a and increases the frequency of the compressor 11 with F2 as the target value. As a result, the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the utilization side heat exchanger 14, and the heating operation is started.

[0101] After the heating operation is started at time t4a, the temperature of room R1 continues to decrease until the heating rate of room R1 exceeds the cooling rate of room R1. Therefore, a minimum value Tp3 appears in the detected temperature between time t4a and time t5.

[0102] As described above, when the detected temperature in the nth defrost operation decreases more rapidly than the first rate of change dTa, the control unit 5 advances the time t4a at which the pressure equalization of the nth defrost operation ends to be earlier than the scheduled end time t4 of the nth defrost operation. In this way, if the nth defrost operation is continued until the original scheduled end time t4, the temperature of the room R1 would have dropped to the minimum value Tp1, but in the actual nth defrost operation, the first time X1a is made shorter so that the temperature of the room R1 can be kept at the minimum value Tp3 higher than Tp1. As a result, it is possible to suppress deterioration of the comfort of the user due to a drop in the temperature of the room R1.

[0103] When the detected temperature in the nth defrost operation decreases more slowly than the first rate of change dTa, the control unit 5 sets the time t4b at which the pressure equalization of the nth defrost operation ends later than the scheduled end time t4 of the nth defrost operation. Since the temperature drop in the room R1 is more gradual than the reference, even if the first time X1b for performing the pressure equalization is extended beyond the first scheduled time X1, the impact on the comfort of the user is small. By making the first time X1b longer, the impact noise of the switching mechanism 15 can be more reliably suppressed. As a result, the deterioration of the comfort of the user due to the impact noise of the switching mechanism 15 can be suppressed.

[0104] In particular, according to the second control example, it is possible to shorten or extend the end time of the pressure equalization control executed in the first state (n-th defrost operation) in which the change in the detected temperature is calculated. This allows the first time to be changed immediately in consideration of the temperature change in room R1, so that it is possible to more reliably prevent the deterioration of user comfort due to a drop in the temperature of room R1.

[0105] [Variations] The present disclosure is not limited to the above embodiment, and various modifications are possible. In the following modifications, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0106] [About the first lesson] See Fig. 5. In the first control example, pressure equalization is performed for a first time X1 in the nth defrost operation. The control unit 5 may determine a reference value for the first time X1 (for example, the first time X1 in the first defrost operation) based on the model of the indoor unit 2. Hereinafter, the reference value for the first time X1 will be simply referred to as the first time X1.

[0107] Conventionally, a certain pressure equalization time has been written as a fixed value in the program installed in the control unit 5, regardless of the model of the indoor unit 2. However, since the volume of the impact sound of the switching mechanism 15 differs depending on the model of the indoor unit 2 (particularly the volume of the indoor unit 2), it is preferable to determine the first time X1 depending on the model of the indoor unit 2.

[0108] For example, the control unit 5 determines the first time X1 based on model information of the indoor unit 2 recorded in the memory 53a. Specifically, the control unit 5 determines a longer first time X1 for a model that is more likely to produce louder impact noise from the switching mechanism 15 (for example, a model with a larger volume). For example, a table that associates model information with the first time X1 may be recorded in the memory 53a, and the first time X1 corresponding to the model information may be read out when the processor 52a executes a program.

[0109] This allows the first time X1 for pressure equalization to be determined taking into consideration the model of the indoor unit 2, thereby more reliably suppressing the impact noise of the switching mechanism 15. In particular, the larger the volume of the indoor unit 2, the more difficult it is to reduce the pressure difference of the switching mechanism 15, and a relatively long pressure equalization time is required. In such cases, by lengthening the first time X1, the impact noise of the switching mechanism 15 can be more reliably suppressed.

[0110] [Modification of the first control example] In the above first control example, the control unit 5 determines the first time X2 in the (n+1)th defrost operation based on the temperature change in the nth defrost operation. In addition to or instead of this control, the control unit 5 may determine the first time in the (n+2)th or subsequent defrost operations based on the temperature change in the nth defrost operation.

[0111] The control unit 5 calculates the change in detected temperature during the nth defrost operation, and based on the calculated change in detected temperature, determines the first time after the switching mechanism 15 has been switched to the second state one or more times since the nth defrost operation for which the change in detected temperature was calculated (the first time during the (n+1)th or later defrost operation).

[0112] [Modification of the detection unit] The control unit 5 in the above embodiment determines the first times X1a, X1b, X2, and X3 based on the detected temperature of the detection unit 21. However, the control unit 5 may determine the first times X1a, X1b, X2, and X3 based on the detected temperature of the detection unit 22.

[0113] [others] At least some of the above-described embodiments and modified examples may be combined with each other in any desired manner.

[0114] [Effects of the embodiment] (1) The refrigeration device 1 of the embodiment includes a refrigerant circuit 4 having a compressor 11, a heat source side heat exchanger 12, a pressure reduction mechanism 13, and a utilization side heat exchanger 14, and through which a refrigerant circulates; a switching mechanism 15 provided in the refrigerant circuit 4, which switches between a first state in which the refrigerant discharged from the compressor 11 is sent to the heat source side heat exchanger 12 and a second state in which the refrigerant discharged from the compressor 11 is sent to the utilization side heat exchanger 14; detection units 21, 22 which detect the temperature of a room R1 in which the utilization side heat exchanger 14 is provided; and a control unit 5 which controls the compressor 11 and the switching mechanism 15, wherein the control unit 5 sets the frequency of the compressor 11 to a predetermined value or lower for a first time before switching from the first state to the second state, and the control unit 5 determines the first time based on a change in the detected temperature of the detection units 21, 22 while the switching mechanism 15 is in the first state.

[0115] With this configuration, the first time for pressure equalization can be determined taking into account the temperature change in the room while in the first state (i.e., defrost operation), thereby preventing a decrease in user comfort when taking measures against the impact noise of the switching mechanism.

[0116] (2) In the embodiment, the control unit 5 shortens the first time period when the detected temperature decreases more rapidly than a first rate of change.

[0117] According to this configuration, when the temperature in the room drops rapidly, the first time period for performing pressure equalization is shortened, thereby making it possible to suppress deterioration of user comfort due to the drop in room temperature.

[0118] (3) In the embodiment, the control unit 5 extends the first time period when the detected temperature decreases at a rate slower than the first rate of change.

[0119] According to this configuration, when the temperature in the room drops slowly, the first time period for performing pressure equalization is extended, so that the impact noise of the switching mechanism can be more reliably suppressed.

[0120] (4) In the embodiment, the control unit 5 calculates the rate of change of the detected temperature every time the switching mechanism 15 is switched to the first state, and determines the first rate of change based on the calculated multiple rates of change.

[0121] According to this configuration, the first change rate that serves as a reference can be determined for each room based on the temperature change rates of multiple past times.

[0122] (5) In the embodiment, the control unit 5 calculates a change in the detected temperature while the switching mechanism 15 is in the first state, and the control unit 5 determines the time to switch from the first state at which the change in detected temperature was calculated to the second state based on the calculated change in detected temperature.

[0123] According to this configuration, it is possible to shorten or extend the end time of the pressure equalization control executed in the first state in which the change in the detected temperature is calculated. This allows the first time to be changed immediately in consideration of the change in the room temperature, so that it is possible to more reliably prevent the deterioration of user comfort due to a drop in the room temperature.

[0124] (6) In the embodiment, the control unit 5 calculates the change in the detected temperature while the switching mechanism 15 is in the first state, and based on the calculated change in the detected temperature, the control unit 5 determines the first time after the switching mechanism 15 has been switched to the second state one or more times from the first state in which the change in the detected temperature was calculated.

[0125] According to this configuration, the calculated change in the detected temperature can be reflected in the first hour from the next time onwards, so that it is possible to more reliably prevent the deterioration of user comfort due to a decrease in the room temperature.

[0126] (7) In the embodiment, the control unit 5 determines the first time period based on the model of the indoor unit 2 that accommodates the utilization side heat exchanger 14.

[0127] According to this configuration, the first time period for performing pressure equalization can be determined taking into consideration the model of the indoor unit, so that the impact noise of the switching mechanism can be more reliably suppressed.

[0128] (8) In the embodiment, the control unit 5 extends the first time period as the volume of the indoor unit 2 increases.

[0129] The larger the volume of the indoor unit, the more difficult it is to reduce the pressure difference in the switching mechanism, and a relatively long pressure equalization time is required. In such cases, the first time can be extended, so the impact noise of the switching mechanism can be more reliably suppressed.

[0130] [Additional Note] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Explanation of symbols]

[0131] 1: refrigeration device, 11: compressor, 12: heat source side heat exchanger, 13: pressure reducing mechanism, 14: utilization side heat exchanger, 15: switching mechanism, 16: accumulator, 2: indoor unit, 21: detection unit, 22: detection unit, 3: outdoor unit, 4: refrigerant circuit, 41: piping, 41a: area, 41b: area, 41c: area, 41d: area, 41e: area, 5: control unit, 5a: indoor control unit, 5b: outdoor control unit, 51: remote control unit (remote control), 52a: processor, 52b: processor, 53a: memory, 53b: memory, 61: indoor fan, 62: outdoor fan, 71: operation switch, 72: operation changeover switch, 73: temperature setting switch, 8: main body, 81: housing, 82: valve body, 83: partition plate, 84: partition plate, 85 : support plate, 85a: through hole, 85b: through hole, 86: connecting pipe, 87: connecting pipe, 88: connecting pipe, 89: connecting pipe, 9: pilot solenoid valve, 91: port, 92: port, 93: port, 94: port, R1: chamber, P1: port, P2: port, P3: port, P4: port, S1: first chamber, S2: second chamber, t1: time, t2: time, t3: time, t4: Time (scheduled end time), t4a: time, t4b: time, t5: time, t6: time, t7: time, X1: 1st hour (1st scheduled time), X1a: 1st hour, X1b: 1st hour, X2: 1st hour, X3: 1st hour, Th1: set temperature, F2: frequency, F1: frequency, Tp1: minimum value, Tp2: minimum value, Tp3: minimum value, dT1: rate of change, dTa: 1st rate of change

Claims

1. a refrigerant circuit (4) having a compressor (11), a heat source side heat exchanger (12), a pressure reducing mechanism (13) and a utilization side heat exchanger (14) and through which a refrigerant circulates; a switching mechanism (15) provided in the refrigerant circuit (4) and switching between a first state in which the refrigerant discharged from the compressor (11) is sent to the heat source side heat exchanger (12) and a second state in which the refrigerant discharged from the compressor (11) is sent to the utilization side heat exchanger (14); a detection unit (21, 22) for detecting a temperature of a room (R1) in which the utilization side heat exchanger (14) is installed; a control unit (5) that controls the compressor (11) and the switching mechanism (15); Equipped with the control unit (5) sets the frequency of the compressor (11) to a predetermined value or less for a first time period before switching from the first state to the second state, the control unit (5) determines the first time based on a change in the detected temperature of the detection unit (21, 22) while the switching mechanism (15) is in the first state; The control unit (5) shortens the first time period when the detected temperature decreases more rapidly than a first rate of change. Refrigeration device (1).

2. The control unit (5) extends the first time period when the detected temperature decreases more slowly than the first rate of change. Refrigeration device (1) according to claim 1.

3. The control unit (5) calculates a rate of change of the detected temperature every time the switching mechanism (15) is switched to the first state, and determines the first rate of change based on the calculated multiple rates of change. Refrigeration device (1) according to claim 1 or claim 2.

4. The control unit (5) calculates a change in the detected temperature while the switching mechanism (15) is in the first state, The control unit (5) determines, based on the calculated change in the detected temperature, a time to switch from the first state to the second state at which the change in the detected temperature has been calculated. Refrigeration device (1) according to any one of claims 1 to 3.

5. The control unit (5) calculates a change in the detected temperature while the switching mechanism (15) is in the first state, The control unit (5) determines, based on the calculated change in the detected temperature, the first time after the switching mechanism (15) has been switched to the second state one or more times from the first state in which the change in the detected temperature was calculated. Refrigeration device (1) according to any one of claims 1 to 4.

6. The control unit (5) determines the first time based on a model of an indoor unit (2) that accommodates the utilization side heat exchanger (14). Refrigeration device (1) according to any one of the preceding claims.

7. The control unit (5) extends the first time period as the volume of the indoor unit (2) increases. Refrigeration device (1) according to claim 6.

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