Heating medium circulation device

Abstract

To provide a heating medium circulation device capable of improving reliability of a compressor.SOLUTION: A heating medium circulation device includes: a refrigerant circuit in which a compressor, a utilization side heat exchanger, a decompression device and a heat source side heat exchanger are sequentially connected; a heating medium circuit in which a heating medium cooled or heated by the utilization side heat exchanger by using a refrigerant from the compressor circulates; a heating medium temperature sensor that detects a temperature of the heating medium flowing into the utilization side heat exchanger; and a control device that controls the decompression device. The control device sets an opening of the decompression device at start of the compressor to a first opening that is set to be larger as the temperature of the heating medium detected by the heating medium temperature sensor is higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heat medium circulator. [Background technology]

[0002] Patent Document 1 discloses a technology in which the initial opening of the pressure reducing device is set to an opening corresponding to the outside air temperature when the compressor is started, and the set initial opening is kept constant for a predetermined time from the start-up regardless of the compressor discharge temperature, thereby ensuring the amount of refrigerant circulating when the compressor is started and shortening the start-up time of the compressor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-346449 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a heat medium circulating device capable of improving the reliability of a compressor. [Means for solving the problem]

[0005] The heat medium circulating device according to the present disclosure includes a refrigerant circuit in which a compressor, a use-side heat exchanger, a pressure reduction device, and a heat source-side heat exchanger are connected in sequence, a heat medium circuit in which a heat medium circulates to be cooled or heated in the use-side heat exchanger by refrigerant from the compressor, a heat medium temperature sensor that detects the temperature of the heat medium flowing into the use-side heat exchanger, and a control device that controls the pressure reduction device, and the control device sets the aperture of the pressure reduction device at the start of the compressor to a first aperture that is set larger as the temperature of the heat medium detected by the heat medium temperature sensor increases. Effect of the Invention

[0006] The heat medium circulating device according to the present disclosure controls the opening degree of the pressure reducing device at the start of the compressor so that the higher the temperature of the heat medium flowing into the user-side heat exchanger, the larger the opening degree of the pressure reducing device at the start of the compressor. Therefore, the refrigerant that has absorbed heat from the heat medium in the user-side heat exchanger and evaporated is not excessively depressurized by the pressure reducing device, and the excessive rise in the discharge temperature of the compressor can be suppressed. Therefore, the reliability of the compressor can be improved. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a heat medium circulator according to a first embodiment. [Diagram 2] FIG. 1 shows a configuration of a control device according to a first embodiment. [Diagram 3] Mollier diagram showing the state of the refrigerant in the first embodiment [Figure 4] 1 is a flowchart showing the operation of the control device according to the first embodiment. [Diagram 5] FIG. 1 is a diagram for explaining a first opening degree in the first embodiment. [Figure 6] FIG. 1 is a diagram for explaining a second opening degree in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (The knowledge and other information that formed the basis of this disclosure) At the time when the inventors arrived at the present disclosure, there was a technique for controlling the opening degree of a pressure reducing device at the start of a compressor in a refrigerant circuit. However, although Patent Document 1 discloses a configuration in which the initial opening degree of the pressure reducing device is reduced as the outside air temperature is lower, it does not disclose how to set the initial opening degree of the pressure reducing device with respect to the temperature of the water flowing into the refrigerant-to-water heat exchanger. Therefore, in Patent Document 1, the initial opening degree of the pressure reducing device is set small regardless of the temperature of the water flowing into the refrigerant-to-water heat exchanger. When the temperature of the water flowing into the refrigerant-to-water heat exchanger is higher than the temperature of the refrigerant, the refrigerant that has absorbed heat from the water and evaporated leaves the refrigerant-to-water heat exchanger. In this case, the higher the temperature of the water flowing into the refrigerant-to-water heat exchanger, the greater the degree of superheat of the refrigerant leaving the refrigerant-to-water heat exchanger. As described above, in the configuration of Patent Document 1, when the compressor is started, the refrigerant vaporized in the refrigerant-to-water heat exchanger is excessively depressurized in the decompression device, and the compressor compresses the refrigerant with a high degree of superheat. Therefore, the inventors discovered a problem in that the discharge temperature of the compressor may rise excessively in the configuration of Patent Document 1, which may impair the reliability of the compressor. In order to solve this problem, the inventors have come to form the subject of the present disclosure. In view of this, the present disclosure provides a heat medium circulating device capable of improving the reliability of a compressor.

[0009] Hereinafter, the embodiments will be described in detail with reference to the drawings. However, in some cases, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations of substantially the same configurations may be omitted. It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0010] (Embodiment 1) [1-1. Configuration] [1-1-1. Configuration of heat transfer medium circulator] FIG. 1 is a diagram showing the configuration of a heat medium circulator 100. As shown in FIG.

[0011] The heat medium circulating device 100 includes an outdoor unit 200 and an indoor unit 300. The outdoor unit 200 includes a refrigerant circuit 1, a part of the heat medium circuit 2, and a control device 3. The indoor unit 300 includes a part of the heat medium circuit 2.

[0012] The refrigerant circuit 1 is a vapor compression refrigeration cycle, in which a compressor 10, a user-side heat exchanger 11, a pressure reducing device 12, and a heat source-side heat exchanger 13 are sequentially connected by refrigerant piping 14. As the refrigerant circulating through the refrigerant circuit 1, for example, propane, which is a flammable refrigerant, is used.

[0013] The refrigerant circuit 1 is provided with a four-way valve 15 for switching between a heating operation for producing hot water and a cooling operation for producing cold water. In Fig. 1, the flow direction of the refrigerant during the heating operation is indicated by a solid arrow, and the flow direction of the refrigerant during the cooling operation is indicated by a dashed arrow.

[0014] The heat medium circuit 2 is a circuit in which a user side heat exchanger 11, an indoor side heat exchanger 20, and a pump 21 functioning as a heat medium transport device are sequentially connected by heat medium piping 22. Water or antifreeze liquid is used as the heat refrigerant circulating through the heat medium circuit 2. In FIG. 1, the flow direction of the heat medium is indicated by a two-dot chain line arrow.

[0015] The control device 3 is a device that controls each part of the heat medium circulating device 100. The control device 3 is connected to various sensors provided in the heat medium circulating device 100, and receives detection values ​​from the various sensors connected thereto.

[0016] Next, various sensors connected to the control device 3 will be described. The heat medium circulating device 100 includes a heat medium temperature sensor 4, a refrigerant condensation temperature sensor 5, an outside air temperature sensor 6, a discharge temperature sensor 7, a first superheat degree detection sensor 8, and a second superheat degree detection sensor 9. The first superheat degree detection sensor 8 is an example of a "first superheat degree detection section." The second superheat degree detection sensor 9 is an example of a "second superheat degree detection section."

[0017] The heat medium temperature sensor 4 is a sensor that detects the temperature of the heat medium flowing into the use-side heat exchanger 11 (hereinafter, appropriately referred to as "heat medium inlet temperature"). The heat medium temperature sensor 4 is provided in the heat medium piping 22, downstream of the pump 21 and upstream of the use-side heat exchanger 11 with respect to the flow direction of the heat medium.

[0018] The condensation temperature sensor 5 is a sensor that detects the condensation temperature of the refrigerant passing through the utilization-side heat exchanger 11, i.e., the saturation temperature of the refrigerant discharged from the compressor 10. The condensation temperature sensor 5 is provided in the refrigerant piping 14, downstream of the compressor 10 and upstream of the pressure reducing device 12, with respect to the refrigerant flow direction. The installation position of the condensation temperature sensor 5 is not limited to the position in Fig. 1, and may be any position between the compressor 10 and the pressure reducing device 12, with respect to the refrigerant flow direction during heating operation.

[0019] The outdoor air temperature sensor 6 is a sensor that detects the outdoor air temperature around where the outdoor unit 200 is installed. The outdoor air temperature sensor 6 is installed at a predetermined position of the outdoor unit 200. The outdoor air temperature sensor 6 may be installed inside the outdoor unit 200 or outside the outdoor unit 200.

[0020] The discharge temperature sensor 7 is a sensor that detects the discharge temperature of the compressor 10 during heating operation. The discharge temperature of the compressor 10 is the temperature of the refrigerant discharged from the compressor 10. The discharge temperature sensor 7 is provided upstream of the utilization side heat exchanger 11 and downstream of the compressor 10 with respect to the flow direction of the refrigerant during heating operation.

[0021] The first superheat degree detection sensor 8 is a sensor that detects the degree of superheat of the suction temperature of the compressor 10 during heating operation. The suction temperature of the compressor 10 is the temperature of the refrigerant sucked into the compressor 10. The first superheat degree detection sensor 8 includes a sensor that detects the suction temperature of the compressor 10 and a sensor that detects the pressure of the refrigerant sucked into the compressor 10, and calculates the degree of superheat from the difference between the detected suction temperature and the saturation temperature of the detected pressure. Here, the saturation temperature is derived from an equation for the physical properties of the refrigerant. The first superheat degree detection sensor 8 is provided downstream of the heat source side heat exchanger 13 and upstream of the compressor 10 based on the flow direction of the refrigerant during heating operation.

[0022] The second superheat degree detection sensor 9 is a sensor that detects the degree of superheat of the discharge temperature of the compressor 10 during heating operation. The second superheat degree detection sensor 9 includes a sensor that detects the discharge temperature of the compressor 10 and a sensor that detects the pressure of the refrigerant discharged from the compressor 10, and calculates the degree of superheat from the difference between the detected discharge temperature and the saturation temperature of the detected pressure. Here, the saturation temperature is derived from an equation for the physical properties of the refrigerant. The second superheat degree detection sensor 9 is provided upstream of the utilization side heat exchanger 11 and downstream of the compressor 10 based on the flow direction of the refrigerant during heating operation.

[0023] Next, the configuration of the control device 3 will be described. FIG. 2 is a diagram showing the configuration of the control device 3. As shown in FIG.

[0024] The control device 3 includes a processor 30 such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), a memory 31, and an interface circuit to which other devices and sensors are connected. The control device 3 performs various functions by the processor 30 reading and executing a control program 311 stored in the memory 31. The control program 311 is a program for controlling the heat medium circulating device 100.

[0025] The memory 31 is a memory that stores programs and data. The memory 31 stores a control program 311 and other data to be processed by the processor 30. The memory 31 has a non-volatile storage area. The memory 31 also has a volatile storage area and constitutes a work area of ​​the processor 30. The memory 31 is constituted by, for example, a Read Only Memory (ROM) or a Random Access Memory (RAM).

[0026] Various devices are connected to the control device 3 via the above-mentioned interface circuit. Fig. 2 shows a configuration in which a compressor 10, a heat medium temperature sensor 4, a condensation temperature sensor 5, an outside air temperature sensor 6, a discharge temperature sensor 7, a first superheat degree detection sensor 8, and a second superheat degree detection sensor 9 are connected to the control device 3. However, the devices connected to the control device 3 are not limited to these, and other devices such as a motor that drives a fan may be connected.

[0027] [1-2. Operation] Next, the operation of the heat medium circulating device 100 according to this embodiment will be described. In order to suppress an excessive rise in the discharge temperature of the compressor 10 when the compressor 10 is started, the control device 3 of this embodiment performs the operation described below. First, the mechanism by which the discharge temperature of the compressor 10 increases excessively when the compressor 10 is started will be described with reference to FIG.

[0028] FIG. 3 is a Mollier diagram showing the state of a refrigerant. In explaining the excessive rise in discharge temperature, it is assumed that the outside air temperature is -20°C, the heat medium temperature is +70°C, and the refrigerant temperature is +60°C.

[0029] When the compressor 10 starts, the refrigerant in the compressor 10 is pressurized and changes from a state corresponding to point P1 in FIG. 3 to a state corresponding to point P2 in FIG. 3. However, the refrigerant is condensed by the shell of the compressor 10, which is cooled by the outside air, and the refrigerant discharged from the compressor 10 is in a state corresponding to point P3 in FIG. 3, that is, a two-phase refrigerant. Since the temperature of the refrigerant is lower than the temperature of the heat medium in the use-side heat exchanger 11, the refrigerant that flows into the use-side heat exchanger 11 absorbs heat from the heat medium and vaporizes. Therefore, the refrigerant that flows out of the use-side heat exchanger 11 is a refrigerant with a high degree of superheat and low density. In the Mollier diagram of FIG. 3, the refrigerant that flows out of the use-side heat exchanger 11 is in a state corresponding to point P4 in FIG. 3. The refrigerant that flows out of the use-side heat exchanger 11 is decompressed by the decompression device 12, but the smaller the opening of the decompression device 12, the more excessively the refrigerant is decompressed, and the state corresponds to point P5 in FIG. 3. The refrigerant decompressed by the pressure reducing device 12 absorbs heat in the heat source side heat exchanger 13, so the compressor 10 draws in the refrigerant in a highly superheated state and compresses it. As a result, the refrigerant discharged from the compressor 10 is in a state corresponding to point P6 in Fig. 3, that is, in a state away from the saturated vapor line to the right, and the discharge temperature of the compressor 10 becomes excessive.

[0030] As described above, under conditions where the outside air temperature is low, when the compressor 10 is started, the discharge temperature of the compressor 10 may excessively increase, so the heat medium circulating device 100 of this embodiment executes the following operation.

[0031] FIG. 4 is a flowchart showing the operation of the control device 3. At the start of the flowchart in FIG. 4, the heat medium circulating device 100 is in a stopped state.

[0032] The control device 3 determines whether or not to start the heating operation (step S1). For example, in step S1, when the control device 3 receives a signal to start the heating operation from a device that accepts operations related to the heat medium circulating device 100 from a user, the control device 3 makes a positive determination in step S1.

[0033] When it is determined to start the heating operation (step S1: YES), the control device 3 sets the opening degree of the pressure reducing device 12 to the first opening degree based on the detection value of the heat medium temperature sensor 4 (step S2).

[0034] FIG. 5 is a diagram for explaining the first opening degree. In Fig. 5, the vertical axis represents the opening degree of the pressure reducing device 12. In addition, in Fig. 5, the horizontal axis represents the heat medium inlet temperature. Note that, on the vertical axis in Fig. 5, the maximum opening degree of the pressure reducing device 12 is taken as 100%.

[0035] The first degree of opening is set at the start of the compressor 10. In Fig. 5, a graph GF1 shows the relationship between the first degree of opening and the heat medium inlet temperature. As the graph GF1 shows, the first degree of opening is set to a larger value as the heat medium inlet temperature is higher.

[0036] In FIG. 5, the range of the heat medium inlet temperature is 20°C to 70°C. That is, in the example of FIG. 5, the minimum heat medium inlet temperature is 20°C, and the maximum heat medium inlet temperature is 70°C. In the case of FIG. 5, when the heat medium inlet temperature is 20°C, the first opening degree is set to 70%. Also, in the case of FIG. 5, when the heat medium inlet temperature is 80°C, the first opening degree is set to 85%. Also, in the case of FIG. 5, when the heat medium inlet temperature is more than 20°C and less than 80°C, the first opening degree is set to a larger opening degree the higher the heat medium inlet temperature is. In the example of FIG. 5, the higher the heat medium inlet temperature, the larger the first degree of opening is set proportionally. However, the relationship between the heat medium inlet temperature and the magnitude of the first degree of opening is not limited to a proportional relationship.

[0037] The range of the first opening shown in Fig. 5 is merely an example, and is not limited to between 70% and 85% as long as the range increases with increasing heat medium inlet temperature. The range of the heat medium inlet temperature defining the range of the first opening shown in Fig. 5 is not limited to 20°C to 70°C. The range of the first opening may be defined by a wider range of the heat medium inlet temperature, or may be defined by a narrower range of the heat medium inlet temperature.

[0038] When determining the first degree of opening, the control device 3 may determine it by calculation based on a predetermined algorithm, or may determine it by referring to a table in which the magnitude of the first degree of opening is determined for each heat medium inlet temperature.

[0039] Returning to the explanation of the flowchart shown in Fig. 4, when the control device 3 sets the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 starts driving the compressor 10 (step S3). That is, in step S3, the control device 3 starts up the compressor 10.

[0040] Next, the control device 3 determines whether or not a switching condition for switching the opening degree of the pressure reducing device 12 from the first opening degree to the second opening degree is satisfied (step S4). The second opening degree will be described later.

[0041] Here, a number of switching conditions will be explained. <First switching condition> The first switching condition is that the temperature of the refrigerant flowing into the use side heat exchanger 11 falls below the heat medium inlet temperature. The control device 3 determines whether or not the first switching condition is established based on the detection value of the heat medium temperature sensor 4 and the detection value of the condensation temperature sensor 5. In detail, after setting the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 determines whether or not the temperature detected by the condensation temperature sensor 5 falls below the heat medium inlet temperature detected by the heat medium temperature sensor 4. Then, when the control device 3 determines that the temperature of the refrigerant flowing into the use side heat exchanger 11 falls below the heat medium inlet temperature, it determines that the first switching condition is established.

[0042] <Second switching condition> The second switching condition is that the degree of superheat of the refrigerant sucked by the compressor 10 falls below a predetermined threshold. An example of the predetermined threshold is 2K (Kelvin). The control device 3 determines whether or not the second switching condition is established based on the detection value of the first superheat detection sensor 8. In detail, after setting the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 determines whether or not the degree of superheat detected by the first superheat detection sensor 8 falls below the predetermined threshold. When the control device 3 determines that the degree of superheat detected by the first superheat detection sensor 8 falls below the predetermined threshold, it determines that the second switching condition is established.

[0043] <Third switching condition> The third switching condition is that the degree of superheat of the refrigerant discharged from the compressor 10 exceeds a predetermined threshold. An example of the predetermined threshold is 5K (Kelvin). The control device 3 determines whether or not the third switching condition is established based on the detection value of the second superheat detection sensor 9. In detail, after setting the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 determines whether or not the degree of superheat detected by the second superheat detection sensor 9 exceeds the predetermined threshold. When the control device 3 determines that the degree of superheat detected by the second superheat detection sensor 9 exceeds the predetermined threshold, it determines that the third switching condition is established.

[0044] <Fourth switching condition> The fourth switching condition is that the first preset time has elapsed since the compressor 10 was started. The first preset time is a predetermined time, and the higher the heat medium inlet temperature, the longer the first preset time. After setting the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 determines the first preset time corresponding to the heat medium inlet temperature detected by the heat medium temperature sensor 4. The first preset time may be determined by calculation based on a predetermined algorithm, or may be determined by referring to a table in which the first preset time is determined according to the heat medium inlet temperature. When the control device 3 determines the first preset time, it determines whether the determined first preset time has elapsed since the compressor 10 was started. When the control device 3 determines that the first preset time has elapsed, it determines that the fourth switching condition is established. The first preset time is, for example, 3 minutes when the heat medium inlet temperature is +20°C, and 7 minutes when the heat medium inlet temperature is +70°C.

[0045] <Fifth switching condition> The fifth switching condition is that the second preset time has elapsed since the compressor 10 was started. The second preset time is a predetermined time, and the lower the outdoor air temperature, the longer the second preset time. After setting the opening degree of the pressure reducing device 12 to the first opening degree, the control device 3 determines the second preset time corresponding to the outdoor air temperature detected by the outdoor air temperature sensor 6. The second preset time may be determined by calculation based on a predetermined algorithm, or may be determined by referring to a table in which the second preset time is determined according to the outdoor air temperature. After determining the second preset time, the control device 3 determines whether the determined second preset time has elapsed since the compressor 10 was started. When the control device 3 determines that the second preset time has elapsed, the control device 3 determines that the fifth switching condition is established. The second preset time is, for example, 7 minutes when the outside air temperature is -20°C, and 1 minute when the outside air temperature is +20°C.

[0046] In step S4, a positive judgment may be made if any one of the first to fifth switching conditions described above is satisfied, or a positive judgment may be made if any multiple of the first to fifth switching conditions described above are satisfied.

[0047] Returning to the explanation of step S4, if the control device 3 determines that the switching condition is not satisfied (step S4: NO), it performs the determination of step S4 again.

[0048] On the other hand, when it is determined that the switching condition is met (step S4: YES), the control device 3 sets the opening degree of the pressure reducing device 12 to the second opening degree based on the detection value of the heat medium temperature sensor 4 (step S5).

[0049] FIG. 6 is a diagram for explaining the second opening degree. In Fig. 6, the vertical axis indicates the opening degree of the pressure reducing device 12. Note that the direction of the vertical axis in Fig. 6 where the arrow points is the positive direction. Also, in Fig. 6, the horizontal axis indicates the heat medium inlet temperature. Note that the direction of the horizontal axis in Fig. 6 where the arrow points is the positive direction. In Fig. 6, graph GF2 indicates the relationship between the first opening degree and the heat medium inlet temperature. Also, in Fig. 6, graph GF3 indicates the relationship between the second opening degree and the heat medium inlet temperature.

[0050] The second degree of opening is set next to the first degree of opening after the compressor 10 is started. As shown in Fig. 6, the second degree of opening is set smaller as the heat medium inlet temperature is higher. Also, as shown in Fig. 6, the second degree of opening is smaller than the first degree of opening.

[0051] When determining the second degree of opening, the control device 3 may determine it by calculation based on a predetermined algorithm, or may determine it by referring to a table in which the magnitude of the second degree of opening is determined for each heat medium inlet temperature.

[0052] Returning to the explanation of the flowchart in Fig. 4, when the controller 3 sets the aperture of the pressure reducing device 12 to the second aperture, the controller 3 feedback controls the aperture of the pressure reducing device 12 so that the discharge temperature detected by the discharge temperature sensor 7 becomes the target temperature (step S6). Note that data on the target temperature of the discharge temperature is stored in the memory 31.

[0053] [1-3. Effects, etc.] As described above, the heat medium circulating apparatus 100 includes a refrigerant circuit 1 in which the compressor 10, the use side heat exchanger 11, the pressure reducing device 12, and the heat source side heat exchanger 13 are connected in sequence. The heat medium circulating apparatus 100 also includes a heat medium circuit 2 in which a heat medium to be cooled or heated in the use side heat exchanger 11 by a refrigerant from the compressor 10 circulates. The heat medium circulating apparatus 100 also includes a heat medium temperature sensor 4 that detects the temperature of the heat medium flowing into the use side heat exchanger 11. The heat medium circulating apparatus 100 also includes a control device 3 that controls the pressure reducing device 12. The control device 3 sets the aperture of the pressure reducing device 12 at the start of the compressor 10 to a first aperture that is set larger as the temperature of the heat medium detected by the heat medium temperature sensor 4 becomes higher.

[0054] According to this, the higher the temperature of the heat medium flowing into the user-side heat exchanger 11, the greater the opening of the pressure reducing device 12 at the start of the compressor 10. Therefore, the refrigerant that has absorbed heat from the heat medium in the user-side heat exchanger 11 and evaporated is not excessively depressurized by the pressure reducing device 12, and an excessive rise in the discharge temperature of the compressor 10 can be suppressed. Therefore, the reliability of the compressor 10 can be improved.

[0055] When a switching condition for switching the opening degree of the pressure reducing device 12 is satisfied after the compressor 10 is started, the control device 3 sets the opening degree of the pressure reducing device 12 to a second opening degree that is set smaller as the temperature of the heat medium detected by the heat medium temperature sensor 4 becomes higher.

[0056] After the compressor 10 is started, the temperature of the shell of the compressor 10 gradually increases, so that the temperature of the refrigerant flowing into the use-side heat exchanger 11 gradually increases, and the temperature difference between the heat medium and the refrigerant in the use-side heat exchanger 11 becomes small. Therefore, the refrigerant is less likely to evaporate in the use-side heat exchanger 11, and the risk of the discharge temperature of the compressor 10 becoming excessively high is reduced. Therefore, the control device 3 increases the degree of pressure reduction of the pressure reduction device 12 by setting the second opening degree when the switching condition is satisfied after the compressor 10 is started. As a result, after the timing when the risk of the discharge temperature becoming excessively high is reduced, the temperature of the refrigerant passing through the use-side heat exchanger 11 can be made higher than the temperature of the heat medium, and the heat exchange can be performed efficiently in the use-side heat exchanger 11. Therefore, the reliability of the compressor 10 can be improved, and the energy saving performance of the heat medium circulating device 100 can be improved.

[0057] The heat medium circulating device 100 includes a discharge temperature sensor 7 that detects the discharge temperature of the compressor 10. The control device 3 sets the opening degree of the pressure reducing device 12 to the first opening degree until a switching condition is satisfied. After setting the opening degree of the pressure reducing device 12 to the second opening degree, the control device 3 controls the pressure reducing device 12 based on the detection value of the discharge temperature sensor 7 so that the discharge temperature of the compressor 10 becomes the target temperature.

[0058] Immediately after the compressor 10 is started, it takes time for the discharge temperature of the compressor 10 to rise due to factors such as the heat capacity of the compressor 10 and other components. Therefore, if the opening degree of the pressure reducing device 12 is controlled so that the discharge temperature of the compressor 10 becomes the target temperature, the pressure reducing device 12 may be closed excessively, and the discharge temperature of the compressor 10 may rise excessively. Therefore, the control device 3 maintains the opening degree of the pressure reducing device 12 at the first opening degree until the switching condition is satisfied, thereby effectively suppressing the excessive rise in the discharge temperature of the compressor 10 until the switching condition is satisfied. In addition, after the second opening degree is set, the opening degree of the pressure reducing device 12 is controlled so that the discharge temperature becomes the target temperature, so that the control of the pressure reducing device 12 with good system efficiency for the heat medium circulating device 100 can be executed. As described above, the reliability of the compressor 10 can be further improved, and the energy saving performance of the heat medium circulating device 100 can be further improved.

[0059] The heat medium circulating device 100 includes a condensation temperature sensor 5 that detects the condensation temperature of the refrigerant passing through the use-side heat exchanger 11. The switching condition is that the temperature detected by the condensation temperature sensor 5 exceeds the temperature detected by the heat medium temperature sensor 4.

[0060] When the temperature of the refrigerant flowing into the use-side heat exchanger 11 is higher than the heat medium inlet temperature, the refrigerant heats the heat medium in the use-side heat exchanger 11. Therefore, in this case, the refrigerant does not absorb heat and vaporize in the use-side heat exchanger 11, so the risk of the discharge temperature of the compressor 10 rising too high is reduced. Therefore, the control device 3 sets the aperture of the pressure reducing device 12 to the second aperture in this case. As a result, the aperture of the pressure reducing device 12 is set to the second aperture at an appropriate timing when the risk of the discharge temperature of the compressor 10 rising too high is reduced, so that the system efficiency of the heat medium circulating device 100 is further improved. Therefore, the energy saving performance of the heat medium circulating device 100 can be further improved.

[0061] The heat medium circulating device 100 includes a first superheat degree detection sensor 8 that detects the degree of superheat of the refrigerant sucked by the compressor 10. The switching condition is that the degree of superheat detected by the first superheat degree detection sensor 8 falls below a predetermined threshold value.

[0062] When the degree of superheat of the refrigerant sucked into the compressor 10 decreases, the risk of the discharge temperature of the compressor 10 over-rising decreases. Therefore, the control device 3 sets the aperture of the pressure reducing device 12 to the second aperture when the degree of superheat of the refrigerant sucked into the compressor 10 falls below a predetermined threshold. As a result, the aperture of the pressure reducing device 12 is set to the second aperture at an appropriate timing when the risk of the discharge temperature of the compressor 10 over-rising decreases, so that the system efficiency of the heat medium circulating device 100 is further improved. Therefore, the energy saving performance of the heat medium circulating device 100 can be further improved.

[0063] The heat medium circulating device 100 includes a second superheat degree detection sensor 9 that detects the degree of superheat of the refrigerant discharged from the compressor 10. The switching condition is that the degree of superheat detected by the second superheat degree detection sensor 9 exceeds a predetermined threshold value.

[0064] In general, when the degree of superheat of the discharge temperature of the compressor 10 is small, the solubility of the refrigerant in the lubricating oil of the compressor 10 is large. When the solubility in the lubricating oil is large, the refrigerant in the refrigerant circuit tends to be insufficient, the degree of superheat of the refrigerant sucked by the compressor 10 becomes large, and the discharge temperature of the compressor 10 is likely to overheat. Therefore, the control device 3 sets the aperture of the pressure reducing device 12 to the second aperture at a timing when the solubility in the lubricating oil is small, so that the aperture can be switched to the second aperture at an appropriate timing when the discharge temperature of the compressor 10 is unlikely to overheat. Therefore, the reliability of the compressor 10 can be further improved.

[0065] The switching condition is that a predetermined time has elapsed after the start-up of the compressor 10. This time is longer as the temperature of the heat medium flowing into the utilization side heat exchanger 11 is higher.

[0066] According to this, the higher the heat medium inlet temperature, the longer the time for which the opening degree of the pressure reducing device 12 is set to the first opening degree is set. Therefore, the refrigerant can be decompressed by reducing the amount of pressure reduction until the degree of superheat of the refrigerant that has passed through the user-side heat exchanger 11 becomes small, and the excessive rise in the discharge temperature of the compressor 10 can be further suppressed. Therefore, the reliability of the compressor 10 can be further improved.

[0067] The switching condition is that a predetermined time has elapsed after the start of the compressor 10. The lower the outside air temperature, the longer this time is.

[0068] The lower the outside air temperature, the lower the temperature of the shell of the compressor 10, and the longer the time from when the compressor 10 is started until the temperature of the refrigerant flowing through the user-side heat exchanger 11 becomes higher than the temperature of the heat medium. Therefore, the lower the outside air temperature, the longer the time for which the opening degree of the pressure reducing device 12 is set to the first opening degree. This makes it possible to reduce the amount of pressure reduction and reduce the pressure of the refrigerant until the degree of superheat of the refrigerant that has passed through the user-side heat exchanger 11 becomes small, and makes it possible to further suppress an excessive rise in the discharge temperature of the compressor 10. This makes it possible to further improve the reliability of the compressor 10.

[0069] (Other embodiments) As described above, the above-mentioned first embodiment has been described as an example disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. In addition, it is also possible to combine the components described in the above-mentioned first embodiment to create a new embodiment. Therefore, other embodiments will be exemplified below.

[0070] In the above-described embodiment, the heat medium inlet temperature is exemplified as a parameter for determining the first and second opening degrees. In other embodiments, the parameters for determining the first and second opening degrees may include the outside air temperature in addition to the heat medium inlet temperature. That is, in other embodiments, the control device 3 sets the first opening degree to be larger as the outside air temperature detected by the outside air temperature sensor 6 is lower, and sets the second opening degree to be smaller as the outside air temperature detected by the outside air temperature sensor 6 is lower.

[0071] That is, in the first embodiment, when the first opening degree is set to A% when the heat medium inlet temperature is α°C, in this other embodiment, the lower the outdoor air temperature, the larger the first opening degree is set to A%, and the higher the outdoor air temperature, the smaller the first opening degree is set to A%. For example, when the medium inlet temperature is 20°C, in the first embodiment, the first opening degree is set to 70% according to the graph GF1 in FIG. 5. In this other embodiment, when the medium inlet temperature is 20°C, the lower the outdoor air temperature, the larger the first opening degree is set to 70%. Also, for example, when the medium inlet temperature is 70°C, in the first embodiment, the first opening degree is set to 85% according to the graph GF1 in FIG. 5. In this other embodiment, when the medium inlet temperature is 70°C, the first opening is set to a smaller opening than 85% the higher the outside air temperature is (for example, if the outside air temperature is -20°C, the first opening is set to 85%, and if the outside air temperature is +20°C, the first opening is set to 70%).

[0072] Furthermore, in the first embodiment, if the second opening degree set when the heat medium inlet temperature is β°C is B%, in the other embodiments, the lower the outside air temperature, the smaller the second opening degree set when the heat medium inlet temperature is β°C, and the higher the outside air temperature, the larger the second opening degree set when the heat medium inlet temperature is β°C.

[0073] As described above, in the other embodiments described above, the control device 3 sets the first opening degree to a larger value as the outside air temperature detected by the outside air temperature sensor 6 is lower, and sets the second opening degree to a smaller value as the outside air temperature detected by the outside air temperature sensor 6 is lower. The lower the outdoor air temperature, the lower the shell of the compressor 10 becomes, and the lower the temperature of the refrigerant flowing into the use-side heat exchanger 11 becomes. In other words, the lower the outdoor air temperature, the larger the temperature difference between the refrigerant and the heat medium in the use-side heat exchanger 11 becomes, and the greater the degree of superheat of the refrigerant flowing out of the use-side heat exchanger 11 becomes, so that the possibility of the discharge temperature of the compressor 10 over-rising increases. Therefore, in this other embodiment, the lower the outdoor air temperature, the larger the first opening is set, so that excessive pressure reduction in the pressure reducing device 12 can be suppressed according to the outdoor air temperature. Therefore, the over-rising of the discharge temperature of the compressor 10 can be suppressed regardless of the outdoor air temperature, and the reliability of the compressor 10 can be further improved. In addition, after the second opening is set, the lower the outside air temperature, the greater the pressure reduction in the pressure reducing device 12, so that the pressure of the refrigerant sucked into the compressor 10 decreases, the temperature of the refrigerant passing through the heat source side heat exchanger 13 becomes lower than the temperature of the heat source, and the refrigerant can efficiently absorb heat from the heat source.

[0074] In the above-described first embodiment, the first to fifth switching conditions are exemplified as the switching conditions for switching to the second degree of opening. In other embodiments, the switching condition for switching to the second degree of opening may be any one or more of the first to fifth switching conditions. That is, in other embodiments, the switching condition for switching to the second degree of opening may be some of the first to fifth switching conditions. In this case, the heat medium circulating device 100 only needs to include sensors necessary for determining whether the switching conditions are satisfied, and does not necessarily need to include all of the heat medium temperature sensor 4, the condensation temperature sensor 5, the outside air temperature sensor 6, the discharge temperature sensor 7, the first superheat degree detection sensor 8, and the second superheat degree detection sensor 9.

[0075] In the above-described first embodiment, the first superheat degree detection sensor 8 is exemplified as the first superheat degree detection unit, and the second superheat degree detection sensor 9 is exemplified as the second superheat degree detection unit. In other embodiments, the processor 30 may function as the first superheat degree detection unit and the second superheat degree detection unit. In this case, the heat medium circulating device 100 includes a sensor for detecting the intake temperature of the compressor 10 and a sensor for detecting the pressure of the refrigerant sucked by the compressor 10, instead of the first superheat degree detection sensor 8, and a sensor for detecting the pressure of the refrigerant discharged from the compressor 10, instead of the second superheat degree detection sensor 9. In this case, the processor 30 detects each degree of superheat based on the detection value of the discharge temperature sensor 7 and the detection values ​​of the sensors provided instead of the first superheat degree detection sensor 8 and the second superheat degree detection sensor 9.

[0076] The processor 30 may be composed of a single processor or multiple processors. These processors may be hardware programmed to realize the corresponding functional units. That is, these processors may be composed of, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0077] The configuration of the control device 3 shown in Fig. 2 is an example, and the specific implementation form is not particularly limited. In other words, it is not necessarily necessary to implement hardware corresponding to each unit individually, and it is also possible to implement a configuration in which one processor executes a program to realize the functions of each unit. Also, some of the functions realized by software in the above-mentioned embodiment may be hardware, or some of the functions realized by hardware may be software.

[0078] The step units of the operation shown in Fig. 4 are divided according to the main processing contents in order to facilitate understanding of the operation, and the operation is not limited by the manner in which the processing units are divided or the names thereof. The operation may be divided into more step units according to the processing contents. In addition, one step unit may be divided so as to include more processing. In addition, the order of the steps may be appropriately changed within a range that does not interfere with the purpose of this disclosure.

[0079] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents.

[0080] (Additional Note) The above description of the embodiments discloses the following techniques.

[0081] (Technology 1) A heat medium circulating device comprising: a refrigerant circuit in which a compressor, a user-side heat exchanger, a pressure reduction device, and a heat source-side heat exchanger are connected in sequence; a heat medium circuit in which a heat medium circulates to be cooled or heated in the user-side heat exchanger by refrigerant from the compressor; a heat medium temperature sensor that detects the temperature of the heat medium flowing into the user-side heat exchanger; and a control device that controls the pressure reduction device, wherein the control device sets the aperture of the pressure reduction device at start-up of the compressor to a first aperture that is set larger as the temperature of the heat medium detected by the heat medium temperature sensor increases. According to this, the higher the temperature of the heat medium flowing into the user-side heat exchanger, the larger the opening of the pressure reducing device at the start of the compressor is controlled. Therefore, the refrigerant that absorbs heat from the heat medium in the user-side heat exchanger and vaporizes is not excessively depressurized by the pressure reducing device, and the excessive rise in the discharge temperature of the compressor can be suppressed. Therefore, the reliability of the compressor can be improved.

[0082] (Technology 2) In the heat medium circulating device according to Technology 1, when a switching condition for switching the aperture of the pressure reducing device is satisfied after the compressor is started, the control device sets the aperture of the pressure reducing device to a second aperture that is set smaller as the temperature of the heat medium detected by the heat medium temperature sensor becomes higher. According to this, the temperature difference between the heat medium and the refrigerant in the user-side heat exchanger becomes small, and the degree of pressure reduction of the pressure reduction device can be increased at the timing when the risk of the compressor discharge temperature becoming excessive is reduced. As a result, after the timing when the risk of the compressor discharge temperature becoming excessive is reduced, the temperature of the refrigerant passing through the user-side heat exchanger can be made higher than the temperature of the heat medium, and heat exchange can be performed efficiently in the user-side heat exchanger. This improves the reliability of the compressor and improves the energy saving performance of the heat medium circulating device.

[0083] (Technology 3) The heat medium circulating device according to Technology 2, further comprising a discharge temperature sensor for detecting a discharge temperature of the compressor, wherein the control device sets an opening degree of the pressure reducing device to the first opening degree until the switching condition is satisfied, and after setting the opening degree of the pressure reducing device to the second opening degree, controls the pressure reducing device based on a detection value of the discharge temperature sensor so that the discharge temperature of the compressor becomes a target temperature. According to this, by maintaining the opening degree of the pressure reducing device at the first opening degree until the switching condition is satisfied, it is possible to effectively suppress an excessive rise in the discharge temperature of the compressor until the switching condition is satisfied. In addition, after the second opening degree is set, the opening degree of the pressure reducing device is controlled so that the discharge temperature becomes the target temperature, so that the pressure reducing device can be controlled with good system efficiency for the heat medium circulating device. Therefore, it is possible to further improve the reliability of the compressor and further improve the energy saving performance of the heat medium circulating device.

[0084] (Technology 4) The heat medium circulating device according to Technology 2 or Technology 3, further comprising an outside air temperature sensor for detecting an outside air temperature, wherein the control device sets the first opening degree to be larger as the outside air temperature detected by the outside air temperature sensor is lower, and sets the second opening degree to be smaller as the outside air temperature detected by the outside air temperature sensor is lower. According to this, the lower the outside air temperature, the larger the first opening is set, so that excessive pressure reduction in the pressure reduction device can be suppressed according to the outside air temperature. Therefore, the compressor discharge temperature can be prevented from rising excessively regardless of the outside air temperature, and the reliability of the compressor can be further improved. In addition, after the second opening is set, the lower the outside air temperature, the greater the pressure reduction in the pressure reduction device, so that the pressure of the refrigerant sucked into the compressor decreases, the temperature of the refrigerant passing through the heat source side heat exchanger becomes lower than the temperature of the heat source, and the refrigerant can efficiently absorb heat from the heat source.

[0085] (Technology 5) The heat medium circulating device according to any one of Technology 2 to Technology 4, further comprising a condensation temperature sensor for detecting a condensation temperature of the refrigerant passing through the use-side heat exchanger, wherein the switching condition is that the temperature detected by the condensation temperature sensor exceeds the temperature detected by the heat medium temperature sensor. According to this, the aperture of the pressure reducing device can be set to the second aperture at an appropriate timing when the risk of the compressor discharge temperature excessively increasing is reduced, so that the system efficiency of the heat medium circulating apparatus can be further improved, thereby further improving the energy saving performance of the heat medium circulating apparatus.

[0086] (Technology 6) The heat medium circulating device according to any one of Technology 2 to Technology 5, further comprising a first superheat detection unit that detects a degree of superheat of the refrigerant sucked by the compressor, wherein the switching condition is that the degree of superheat detected by the first superheat detection unit falls below a predetermined threshold value. According to this, the aperture of the pressure reducing device can be set to the second aperture at an appropriate timing when the risk of the compressor discharge temperature excessively increasing is reduced, so that the system efficiency of the heat medium circulating apparatus can be further improved, thereby further improving the energy saving performance of the heat medium circulating apparatus.

[0087] (Technology 7) The heat medium circulating device according to any one of Technology 2 to Technology 6, further comprising a second superheat detection unit that detects a degree of superheat of the refrigerant discharged from the compressor, wherein the switching condition is that the degree of superheat detected by the second superheat detection unit exceeds a predetermined threshold value. According to this, the opening degree can be switched to the second opening degree at a timing when the solubility of the refrigerant in the lubricating oil is low and the discharge temperature of the compressor is unlikely to rise excessively, thereby further improving the reliability of the compressor.

[0088] (Technology 8) The heat medium circulating device according to any one of Technology 2 to Technology 7, wherein the switching condition is that a predetermined time has elapsed after start-up of the compressor, and the time is longer as the temperature of the heat medium flowing into the use side heat exchanger is higher. According to this, the time for which the opening degree of the pressure reducing device is set to the first opening degree can be made longer as the temperature of the heat medium flowing into the use-side heat exchanger is higher. Therefore, the refrigerant can be decompressed by reducing the amount of pressure reduction until the degree of superheat of the refrigerant that has passed through the use-side heat exchanger becomes small, and the excessive rise in the discharge temperature of the compressor can be further suppressed. Therefore, the reliability of the compressor can be further improved.

[0089] (Technology 9) The heat medium circulating device according to any one of Technology 2 to Technology 8, wherein the switching condition is that a predetermined time has elapsed since the compressor was started, and the lower the outside air temperature, the longer the time. According to this, the time for which the opening degree of the pressure reducing device is set to the first opening degree is made longer as the outside air temperature is lower. This allows the refrigerant to be decompressed by reducing the amount of pressure reduction until the degree of superheat of the refrigerant that has passed through the user-side heat exchanger becomes small, and the excessive rise in the discharge temperature of the compressor can be further suppressed. Therefore, the reliability of the compressor can be further improved. [Industrial Applicability]

[0090] INDUSTRIAL APPLICABILITY As described above, the heat medium circulating device according to the present invention can be used in devices in which a heat medium and a refrigerant exchange heat, such as hot water supply and heating devices. [Explanation of symbols]

[0091] 1 Refrigerant circuit 2 Heat medium circuit 3. Control device 4 Heat medium temperature sensor 5 Condensation Temperature Sensor 6. Outside Air Temperature Sensor 7 Discharge temperature sensor 8. First superheat detection sensor (first superheat detection section) 9 Second superheat detection sensor (second superheat detection section) 10 Compressor 11 User side heat exchanger 12 Pressure reducing device 13 Heat source side heat exchanger 14 Refrigerant piping 15 Four-way valve 20 Indoor heat exchanger 21 Pump 22 Heat medium piping 30 processors 30 Memory 31 Memory 100 Heat medium circulation device 200 outdoor unit 300 indoor unit 311 Control Program GF1~GF3 graph P1~P6 points

Claims

1. a refrigerant circuit in which a compressor, a utilization-side heat exchanger, a pressure reducing device, and a heat source-side heat exchanger are connected in sequence; a heat medium circuit in which a heat medium to be cooled or heated in the utilization side heat exchanger by a refrigerant from the compressor circulates; a heat medium temperature sensor for detecting a temperature of the heat medium flowing into the utilization side heat exchanger; A control device for controlling the pressure reducing device, the control device sets an opening degree of the pressure reducing device at the start of the compressor to a first opening degree that is set larger as the temperature of the heat medium detected by the heat medium temperature sensor increases. Heat medium circulation device.

2. The control device includes: setting the opening degree of the pressure reducing device to the first opening degree during a period from when the compressor is started until a switching condition for switching the opening degree of the pressure reducing device is satisfied; When the switching condition is satisfied, the opening degree of the pressure reducing device is set to a second opening degree that is set to a smaller value as the temperature of the heat medium detected by the heat medium temperature sensor becomes higher. The heat medium circulating device according to claim 1 .

3. A discharge temperature sensor is provided to detect a discharge temperature of the compressor. After setting the opening degree of the pressure reducing device to the second opening degree, the control device controls the pressure reducing device based on the detection value of the discharge temperature sensor so that the discharge temperature of the compressor becomes a target temperature. The heat medium circulating device according to claim 2 .

4. An outside air temperature sensor is provided to detect the outside air temperature, The control device sets the first opening degree to be larger as the outside air temperature detected by the outside air temperature sensor is lower, and sets the second opening degree to be smaller as the outside air temperature detected by the outside air temperature sensor is lower. The heat medium circulating device according to claim 2 or 3.

5. a condensation temperature sensor for detecting a condensation temperature of the refrigerant passing through the utilization-side heat exchanger; The switching condition is that the temperature detected by the condensation temperature sensor exceeds the temperature detected by the heat medium temperature sensor. The heat medium circulating device according to claim 2 or 3.

6. A first superheat detection unit is provided for detecting a superheat degree of the refrigerant sucked by the compressor, The switching condition is that the superheat degree detected by the first superheat degree detection unit falls below a predetermined threshold value. The heat medium circulating device according to claim 2 or 3.

7. a second superheat detection unit for detecting a superheat degree of the refrigerant discharged from the compressor; The switching condition is that the superheat degree detected by the second superheat degree detection unit exceeds a predetermined threshold value. The heat medium circulating device according to claim 2 or 3.

8. the switching condition is that a predetermined time has elapsed after the compressor is started, The time is longer as the temperature of the heat medium flowing into the use side heat exchanger is higher. The heat medium circulating device according to claim 2 or 3.

9. the switching condition is that a predetermined time has elapsed after the compressor is started, The lower the outside air temperature, the longer the time. The heat medium circulating device according to claim 2 or 3.

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