Refrigeration cycle device

Abstract

To provide a refrigeration cycle device that can suppress load on a compressor from becoming excessive when activating the compressor.SOLUTION: A refrigeration cycle device includes: a by-pass refrigerant circuit branching from a main refrigerant circuit between a utilization-side heat exchanger and an expansion valve, and communicating with an injection port via an economizer; a by-pass valve provided in the by-pass refrigerant circuit and changing a degree of opening of the by-pass refrigerant circuit; a discharge pressure sensor for detecting the pressure of a refrigerant discharged from the compressor; and a controller which executes high discharge pressure-handling processing of gradually increasing the degree of opening of the by-pass refrigerant circuit from a first prescribed degree of opening to a second prescribed degree of opening via the by-pass valve when the pressure detected by the discharge pressure sensor is higher than a prescribed determination pressure during activation of the compressor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device.

Background Art

[0002] Patent Document 1 discloses a configuration including an economizer connected between a utilization-side heat exchanger and an expansion valve, a bypass refrigerant circuit branched from a refrigerant circuit between the utilization-side heat exchanger and the economizer and communicating with a compressor via the economizer, and a bypass valve for changing the opening degree of the bypass refrigerant circuit, in a heat pump system having a main refrigerant circuit in which a compressor, a condenser (utilization-side heat exchanger), an expansion valve, and an evaporator (heat source-side heat exchanger) are connected in sequence.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a refrigeration cycle device capable of suppressing an excessive load on a compressor when the compressor is started.

Means for Solving the Problems

[0005] The refrigeration cycle device in the present disclosure includes a compressor having an injection port communicating with a compression chamber, a utilization-side heat exchanger, an economizer, an expansion valve, and a heat source-side heat exchanger, which are connected in sequence to form a main refrigerant circuit through which the refrigerant circulates, a bypass refrigerant circuit that branches from the main refrigerant circuit between the utilization-side heat exchanger and the expansion valve and communicates with the injection port via the economizer, a bypass valve provided in the bypass refrigerant circuit for changing the opening degree of the bypass refrigerant circuit, a discharge pressure sensor for detecting the pressure of the refrigerant discharged from the compressor, and a controller that executes a high discharge pressure corresponding process of gradually increasing the opening degree of the bypass refrigerant circuit from a first predetermined opening degree to a second predetermined opening degree by the bypass valve when the detected pressure of the discharge pressure sensor is higher than a predetermined determination pressure at the start of the compressor.

Advantages of the Invention

[0006] The refrigeration cycle device of the present disclosure can suppress the excessive load of the compressor when the compressor is started.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0008] (Knowledge, etc. on which the present disclosure is based)

[0009] When the inventors came up with the present disclosure, in a heat pump system having a main refrigerant circuit in which a compressor, a condenser (utilization-side heat exchanger), an expansion valve, and an evaporator (heat source-side heat exchanger) were connected in sequence, an economizer connected between the utilization-side heat exchanger and the expansion valve, a bypass refrigerant circuit branched from the refrigerant circuit between the utilization-side heat exchanger and the economizer and communicating with a multi-stage compression type compressor via the economizer, and a bypass valve for changing the opening degree of the bypass refrigerant circuit were provided. With this technology, the refrigeration effect can be enhanced compared to the case of adopting a single-stage compression type compressor.

[0010] However, the inventors discovered that in the case of the above technology, depending on the situation at the start-up of the compressor, the load on the compressor may become excessive. In order to solve this problem, the inventors came to configure the subject matter of the present disclosure. Therefore, the present disclosure provides a refrigeration cycle device capable of suppressing the load on the compressor from becoming excessive at the start-up of the compressor.

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. However, a more detailed description may be omitted as necessary. For example, a detailed description of already well-known matters or a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description overly redundant and to facilitate the understanding of those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims thereby.

[0012] (Embodiment) Hereinafter, embodiments will be described with reference to FIGS. 1 to 4. [1. Configuration] FIG. 1 is a configuration diagram of a refrigeration cycle device 1 according to the present embodiment. The refrigeration cycle device 1 is a vapor compression refrigeration cycle device, and includes a main refrigerant circuit 10, a bypass refrigerant circuit 20, and a controller 50. The refrigeration cycle device 1 is installed outdoors and is connected to a heating terminal (not shown) by a user-side heat medium circuit 100 to constitute a hot water heating system.

[0013] The main refrigerant circuit 10 is configured by sequentially connecting a compressor 11 that compresses the refrigerant, a user-side heat exchanger 12 that functions as a radiator, an economizer 13, an expansion valve 14, and a heat source-side heat exchanger 15 that functions as an evaporator, by a refrigerant pipe 16. The expansion valve 14 is an opening adjustment valve whose opening can be changed. The refrigerant is, for example, a propane refrigerant such as R290. Note that a refrigerant other than the propane refrigerant may be used.

[0014] The bypass refrigerant circuit 20 branches from the main refrigerant circuit 10 between the user-side heat exchanger 12 and the main expansion valve 14 and communicates with an injection port 11a provided in the compression chamber of the compressor 11. The compressor 11 is a scroll-type two-stage compressor. A bypass valve 21 and an economizer 13 are connected to the bypass refrigerant circuit 20 in order from the upstream side. The bypass valve 21 is an opening adjustment valve whose opening can be changed.

[0015] A part of the high-pressure refrigerant that has passed through the user-side heat exchanger 12 flows into the bypass refrigerant circuit 20 and is decompressed by the bypass valve 21 to become an intermediate-pressure refrigerant. The intermediate-pressure refrigerant exchanges heat with the high-pressure refrigerant flowing through the main refrigerant circuit 10 in the economizer 13 and is then injected into the compressor 11. The refrigerant injected into the compressor 11 merges with the refrigerant that is in the process of being compressed in the compression chamber of the compressor 11. The compressor 11 merges the injected refrigerant and the refrigerant that is in the process of being compressed and performs recompression.

[0016] The utilization-side heat medium circuit 100 is configured by connecting a utilization-side heat exchanger 12, a transfer pump 102, and a heating terminal (not shown) with a heat medium pipe 101. As the heat medium flowing through the utilization-side heat medium circuit 100, water or antifreeze can be used. In this embodiment, water is used as the heat medium, and the heat medium pipe 101 corresponds to the water pipe of the present disclosure. The utilization-side heat exchanger 12 heats the water flowing through the utilization-side heat medium circuit 100 by performing heat exchange between the water flowing through the utilization-side heat medium circuit 100 and the refrigerant discharged from the compressor 11 into the main refrigerant circuit 10. The water heated by the utilization-side heat exchanger 12 is used for heating by heat radiation from the heating terminal, and the water cooled by heat radiation from the heating terminal is reheated by the utilization-side heat exchanger 12 again.

[0017] When the refrigeration cycle device 1 constitutes a hot water storage type hot water supply system, the heat medium pipe 101 is connected to the upper and lower parts of the hot water storage tank, and the water stored in the hot water storage tank is supplied into the hot water storage tank from the upper part of the hot water storage tank through the heat medium pipe 101 by the water heated by the utilization-side heat exchanger 12, and low-temperature water is supplied from the lower part of the hot water storage tank to the heat medium pipe 101 and heated by the utilization-side heat exchanger 12.

[0018] A discharge pressure sensor 40 for detecting the pressure of the refrigerant discharged from the compressor 11 is provided in the main refrigerant pipe 16 on the discharge side of the compressor 11. A water temperature sensor 42 for detecting the temperature of the water flowing into the utilization-side heat exchanger 12 is provided in the heat medium pipe 101 on the inlet side of the utilization-side heat exchanger 12. An outside air temperature sensor 41 for detecting the outside air temperature is provided near the heat source side heat exchanger 15.

[0019] Figure 2 is a control block diagram of the refrigeration cycle device 1. Referring to Figure 2, the controller 50 is connected to the discharge pressure sensor 40, the outside air temperature sensor 41, and the water temperature sensor 42, and detection signals from these sensors are input into the controller 50. Further, the controller 50 is connected to the compressor 11, the expansion valve 14, the heat source fan 17, the bypass valve 21, and the transfer pump 102, and the operations of these controlled objects are controlled by control signals output from the controller 50.

[0020] A remote controller 60 for performing operations such as starting and stopping the operation of the refrigeration cycle device 1 is connected to the controller 50. The remote controller 60 has a switch and a display unit. When an operation signal of the switch is input to the controller 50, the operating state of the refrigeration cycle device 1 is displayed on the display unit of the remote controller 60 according to the display signal output from the controller 50.

[0021] The controller 50 includes a processor 51, a memory 52, etc. In the memory 52, a program 53 for controlling the refrigeration cycle device 1 and control data 54 for determining control conditions of the refrigeration cycle device 1 are stored. The processor 51 controls the operation of the refrigeration cycle device 1 by reading and executing the program 53.

[0022] [2. Control Processing at Startup of Compressor] The procedure of the control processing executed by the controller 50 when the compressor 11 is started will be described according to the flowchart shown in FIG. 3. For example, when the controller 50 starts the circulation of water in the utilization-side heat medium circuit 100 by the transfer pump 102 and the circulation of the refrigerant in the main refrigerant circuit 10 by the compressor 11 in response to the start operation of the heating operation by the remote controller 60, the processing according to the flowchart shown in FIG. 3 is executed.

[0023] The controller 50 starts the compressor 11 in step S1 of FIG. 3 and sets the opening degree of the expansion valve 14 to the initial opening degree in step S2. In the subsequent step S3, the controller 50 recognizes the outside air temperature based on the detection signal of the outside air temperature sensor 41. In the next step S4, the controller 50 recognizes the temperature of the water flowing into the utilization-side heat exchanger 12 based on the detection signal of the water temperature sensor 42.

[0024] In the subsequent step S5, the controller 50 sets a determination pressure for determining the level of the pressure of the refrigerant discharged from the compressor 11 by using a data table included in the control data 54 (see FIG. 2) according to the rotational speed of the compressor 11, the outside air temperature, and the water temperature. The data table uses the rotational speed of the compressor 11, the outside air temperature, and the temperature of the water flowing into the utilization side heat exchanger 12 as input parameters, and the corresponding determination pressure as an output parameter.

[0025] The data table is created based on the results of experiments, computer simulations, etc. With the data table, the determination pressure is set, for example, as in the following setting example 1 and setting example 2. Setting example 1... When the rotational speed of the compressor 11 is 80 Hz, the outside air temperature is -3 to 5 degrees, and the water temperature is 33 to 37 degrees, the determination pressure is set to 2.17 MPa. Setting example 2... When the rotational speed of the compressor 11 is 90 Hz, the outside air temperature is -17 to -10 degrees, and the water temperature is 32 degrees or less, the determination pressure is set to 1.61 MPa. In this way, the determination pressure is set according to the rotational speed of the compressor 11 and the outside air temperature. Basically, the higher the rotational speed of the compressor 11, the lower the determination pressure is set, and the higher the outside air temperature, the higher the determination pressure is set.

[0026] The controller 50 applies the rotational speed of the compressor 11 and the outside air temperature and water temperature recognized in steps S3 and S4 to the data table to set the determination pressure. In the next step S6, the controller 50 recognizes the pressure of the refrigerant discharged from the compressor 11 (discharge pressure) based on the detection signal of the discharge pressure sensor 40. In the subsequent step S7, the controller 50 determines whether the discharge pressure is higher than the determination pressure. Then, when the discharge pressure is higher than the determination pressure, the controller 50 proceeds to step S20, and when the discharge pressure is equal to or lower than the determination pressure, the controller 50 proceeds to step S8.

[0027] In step S8, the controller 50 immediately switches the opening degree of the bypass valve 21 from V1 (corresponding to the first predetermined opening degree of the present disclosure) to V2 (corresponding to the second predetermined opening degree of the present disclosure) (for example, at the maximum setting speed of the bypass valve 21), and proceeds with the process to step S9.

[0028] On the other hand, in step S20, the controller 50 executes a process of gradually increasing the opening degree of the bypass valve 21 from V1 to V2 (high discharge pressure corresponding process), and proceeds with the process to step S9. In step S9, the controller 50 starts the feedback control of the bypass valve 21. In the next step S10, the controller 50 starts the feedback control of the expansion valve 14. The controller 50 feedback-controls the rotation speed of the compressor 11, the opening degree of the expansion valve 14, and the opening degree of the bypass valve 21 so that the temperature of the water flowing out from the utilization-side heat exchanger 12 to the heat medium pipe 101 becomes the target temperature, and adjusts the heating capacity of the utilization-side heat exchanger 12.

[0029] Here, FIG. 4 shows the vertical axis set to the opening degree pls of the bypass valve 21 and the horizontal axis set to the time t. The change in the opening degree of the bypass valve 21 by the process of step S8 is indicated by A, and the change in the opening degree of the bypass valve 21 by the process of step S20 is indicated by B.

[0030] In FIG. 4, t1 is the time point when the process of opening the bypass valve 21 from V1 to V2 is started in step S8 or step S20, and t2 is the time point when the opening degree of the bypass valve 21 becomes V2 by the process in step S20. In the pattern A by the control of step S8, at t1, the opening degree of the bypass valve 21 immediately switches from V1 to V2, and the feedback control of the bypass valve 21 is started.

[0031] On the other hand, in the pattern of B by the process of step S20, the opening degree of the bypass valve 21 increases step by step from t1 to t2. t1 to t2 is, for example, 15 seconds, and V2 is an opening degree increased by 30 pulses more than V1. In FIG. 4, the opening degree of the bypass valve 21 is increased step by step, but it may be increased linearly and steplessly. In this way, when the discharge pressure of the compressor 11 is higher than the determination pressure, by gradually increasing the opening degree of the bypass valve 21, it is possible to avoid a sudden increase in the refrigerant injected into the bypass valve 21 and suppress the load of the compressor 11 from becoming excessive.

[0032] Further, since the feedback control of the opening degree of the expansion valve 14 starts in step S10, the feedback control of the opening degree of the expansion valve 14 is put on standby (prohibited) while the opening degree of the bypass valve 21 is gradually increasing by the control of step S20. Thereby, it is possible to suppress an increase in the load of the compressor 11 due to fluctuations in the amount of refrigerant sucked into the compressor 11.

[0033] [3. Effects, etc.] As described above, in the present embodiment, the refrigeration cycle device 1 includes a compressor 11 having an injection port 11a communicating with a compression chamber, a use-side heat exchanger 12, an economizer 13, an expansion valve 14, and a heat source-side heat exchanger 15, which are connected in order to form a main refrigerant circuit 10 through which the refrigerant circulates, a bypass refrigerant circuit 20 that branches from the main refrigerant circuit 10 between the use-side heat exchanger 12 and the expansion valve 14 and communicates with the injection port 11a via the economizer 13, a bypass valve 21 provided in the bypass refrigerant circuit 20 for changing the opening degree of the bypass refrigerant circuit 20, a discharge pressure sensor 40 for detecting the pressure of the refrigerant discharged from the compressor, and a controller 50 that executes a high discharge pressure corresponding process of gradually increasing the opening degree of the bypass refrigerant circuit 20 from a first predetermined opening degree to a second predetermined opening degree by the bypass valve 21 when the detected pressure of the discharge pressure sensor 40 is higher than a predetermined determination pressure at the start of the compressor 11. In the refrigeration cycle device 1, when the controller 50 detects that the pressure detected by the discharge pressure sensor 40 is higher than the determination pressure at the start of the compressor 11, the controller 50 executes a high discharge pressure corresponding process of gradually increasing the opening degree of the bypass refrigerant circuit 20 from a first predetermined opening degree to a second predetermined opening degree by means of the bypass valve 21, thereby avoiding a sudden increase in the refrigerant injected into the injection port of the compressor 11 and suppressing an excessive load on the compressor 11.

[0034] (Other embodiments) As described above, the above embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments with changes, replacements, additions, omissions, etc.

[0035] In the above embodiment, while the controller 50 executes the process of gradually increasing the opening degree of the bypass valve 21 (high discharge pressure corresponding process) in step S20 of FIG. 3, the feedback control of the expansion valve 14 waits until the process of step S20 is completed. As another embodiment, a configuration that does not perform this waiting may be used.

[0036] In the above embodiment, the controller 50 sets the determination pressure according to the rotational speed of the compressor 11, the outside air temperature, and the temperature of the water flowing into the utilization side heat exchanger 12 in step S5 of FIG. 3. As another embodiment, the determination pressure may be set according to other conditions such as only the rotational speed of the compressor 11, or the determination pressure may be a fixed value.

[0037] The controller in the present disclosure may be any device that can control the device in the present disclosure. When expressing the subject matter of the invention, in addition to the controller, control means or controller or similar terms may be used to represent what controls the device of the present disclosure. The controller can be realized in various ways. For example, a processor may be used as the controller. If a processor is used as the controller, a program can be read from a storage medium storing the program into the processor, and the processor can execute the program to perform various processes. Therefore, by changing the program stored in the storage medium, the processing content can be changed, so the degree of freedom in changing the control content can be increased. Examples of the processor include a CPU (Central Processing Unit) and an MPU (Micro-Processing Unit). Examples of the storage medium include a hard disk, a flash memory, and an optical disk. Also, wired logic with unrewritable programs may be used as the controller. If wired logic is used as the controller, it is effective for improving the processing speed. Examples of the wired logic include an ASIC (Application Specific Integrated Circuit). Further, the controller may be realized by combining a processor and wired logic. By realizing the controller by combining a processor and wired logic, the degree of freedom in software design can be increased while improving the processing speed. Also, the controller and a circuit having a function different from the controller may be configured by one semiconductor element. Examples of the circuit having a different function include an A / D·D / A conversion circuit. Also, the controller may be configured by one semiconductor element or a plurality of semiconductor elements. When configured by a plurality of semiconductor elements, each control described in the claims may be realized by different semiconductor elements. Furthermore, the controller may be configured by a configuration including a semiconductor element and passive components such as resistors or capacitors.

[0038] Note that the above-described embodiments are for exemplifying the technology in the present disclosure, and thus various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or their equivalents.

[0039] (Addition) From the description of the above embodiments, the following technology is disclosed.

[0040] (Technology 1) A compressor having an injection port communicating with a compression chamber, a utilization-side heat exchanger, an economizer, an expansion valve, and a heat source-side heat exchanger are connected in sequence to form a main refrigerant circuit in which the refrigerant circulates, a bypass refrigerant circuit that branches from the main refrigerant circuit between the utilization-side heat exchanger and the expansion valve and communicates with the injection port via the economizer, a bypass valve provided in the bypass refrigerant circuit for changing the opening degree of the bypass refrigerant circuit, a discharge pressure sensor for detecting the pressure of the refrigerant discharged from the compressor, and a controller that, when the detection pressure of the discharge pressure sensor is higher than a predetermined determination pressure at the start of the compressor, executes a high discharge pressure corresponding process of gradually increasing the opening degree of the bypass refrigerant circuit from a first predetermined opening degree to a second predetermined opening degree by the bypass valve. A refrigeration cycle apparatus comprising the same. With this configuration, it is possible to suppress the load of the compressor from becoming excessive at the start of the compressor.

[0041] (Technology 2) The expansion valve has an opening degree changing function, and the controller waits for the execution of the opening degree adjustment control of the expansion valve during the execution of the high discharge pressure corresponding process, and starts the opening degree adjustment control of the expansion valve after the completion of the high discharge pressure corresponding process. The refrigeration cycle apparatus according to Technology 1. With this configuration, it is possible to avoid a reduction in the effect of suppressing the load of the compressor due to the high discharge pressure corresponding process from becoming excessive due to fluctuations in the amount of refrigerant sucked into the compressor by the opening degree adjustment control of the expansion valve.

[0042] (Technology 3) The refrigeration cycle device is installed outdoors. The utilization-side heat exchanger is connected to a water pipe and exchanges heat between the water flowing through the water pipe and the refrigerant flowing through the main refrigerant circuit. The device includes an outdoor air temperature sensor for detecting the outdoor air temperature and a water temperature sensor for detecting the temperature of the water flowing from the water pipe into the utilization-side heat exchanger. The controller sets the determination pressure based on the detected temperature of the outdoor air temperature sensor and the detected temperature of the water temperature sensor. The refrigeration cycle device according to Technology 1 or Technology 2. In this configuration, the load applied to the compressor when discharging the refrigerant from the compressor varies according to the temperature difference between the temperature of the water flowing from the water pipe into the utilization-side heat exchanger and the outdoor air temperature. Therefore, by changing the determination pressure based on the detected temperature of the outdoor air temperature sensor and the detected temperature of the water temperature sensor, it is possible to more appropriately set the timing for executing the high discharge pressure countermeasure process.

[0043] (Technology 4) The refrigerant is a propane refrigerant. The refrigeration cycle device according to Technology 1 or Technology 2. With this configuration, when using a flammable propane refrigerant, it is possible to suppress the load on the compressor from becoming excessive and the temperature of the compressor from rising excessively.

Industrial Applicability

[0044] The present disclosure is applicable to applications for suppressing the load on the compressor from becoming excessive when the compressor is started.

Explanation of Reference Numerals

[0045] 1 Refrigeration cycle device 10 Main refrigerant circuit 11 Compressor 12 Utilization-side heat exchanger 13 Economizer 14 Main expansion valve 15 Heat source-side heat exchanger 16 Refrigerant pipe 17 Four-way valve 20 Bypass refrigerant circuit 21 Bypass expansion valve 30 Bypass refrigerant circuit 31 bypass two-way valve 40 discharge pressure sensor 41 outside air temperature sensor 42 water temperature sensor 50 controller 60 remote control 100 user-side heat medium circuit 101 heat medium circuit 102 transfer pump

Claims

1. A compressor having an injection port communicating with a compression chamber, a utilization-side heat exchanger, an economizer, an expansion valve, and a heat source-side heat exchanger are connected in sequence to form a main refrigerant circuit through which refrigerant circulates, A bypass refrigerant circuit that branches from the main refrigerant circuit between the utilization-side heat exchanger and the expansion valve and communicates with the injection port via the economizer, A bypass valve provided in the bypass refrigerant circuit for changing the opening degree of the bypass refrigerant circuit, A discharge pressure sensor for detecting the pressure of the refrigerant discharged from the compressor, A controller that, when the detected pressure of the discharge pressure sensor is higher than a predetermined determination pressure at the start of the compressor, executes a high discharge pressure corresponding process of gradually increasing the opening degree of the bypass refrigerant circuit from a first predetermined opening degree to a second predetermined opening degree by the bypass valve, A refrigeration cycle device comprising the above.

2. The expansion valve has an opening degree changing function, The controller waits for the execution of the opening degree adjustment control of the expansion valve during the execution of the high discharge pressure corresponding process, and starts the opening degree adjustment control of the expansion valve after the completion of the high discharge pressure corresponding process The refrigeration cycle device according to Claim 1.

3. The refrigeration cycle device is installed outdoors, The utilization-side heat exchanger is connected to a water pipe and performs heat exchange between the water flowing through the water pipe and the refrigerant flowing through the main refrigerant circuit, An outside air temperature sensor for detecting the outside air temperature, A water temperature sensor for detecting the temperature of the water flowing from the water pipe into the utilization-side heat exchanger, and comprising: The controller sets the determination pressure based on the detected temperature of the outside air temperature sensor and the detected temperature of the water temperature sensor The refrigeration cycle device according to Claim 1 or Claim 2.

4. The refrigerant is a propane refrigerant The refrigeration cycle device according to claim 1 or claim 2.

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