Refrigeration device, environment forming device, and refrigeration method

Abstract

The invention provides a refrigeration device, an environment forming device and a refrigeration method. The refrigeration device is provided with: a first injection flow path that branches off from a main circuit and injects a refrigerant through a subcooler into a portion midway in the compression process of a compressor; a first injection regulating valve disposed on the upstream side of the subcooler in the first injection flow path; a first valve control means for controlling the first injection regulating valve such that the degree of superheat of the refrigerant injected through the first injection flow path reaches a target degree of superheat; a receiving unit that receives a refrigeration request level; and a target degree of superheat control means for setting the target degree of superheat to a first value when the degree of refrigeration demand received by the reception unit is a first degree of refrigeration demand, and setting the target degree of superheat to a second value higher than the first value when the degree of refrigeration demand received by the reception unit is a second degree of refrigeration demand lower than the first degree of refrigeration demand. Therefore, the refrigerant can be injected into the midway part of the compression process in the compressor, and energy conservation can be realized.

Description

Technical Field

[0001] The invention relates to a refrigeration device, an environment forming device and a refrigeration method. Background Art

[0002] In the past, as disclosed in Japanese Patent Publication No. 2010-60179, a refrigeration device is known that is provided with a flow path for injecting gas refrigerant into the intermediate pressure portion of a compressor provided in a refrigeration circuit. Specifically, the refrigeration device includes: a main circuit in which a compressor, a condenser, an economizer heat exchanger, an expansion valve, and an evaporator are provided in sequence and in which the refrigerant circulates; and an intermediate injection circuit connected to the main circuit. The liquid refrigerant condensed in the condenser flows into the intermediate injection circuit. The liquid refrigerant is decompressed by the second expansion valve in the intermediate injection circuit and then vaporized by the economizer heat exchanger arranged in the main circuit. The vaporized refrigerant is injected into the intermediate pressure portion of the compressor. The second expansion valve provided in the intermediate injection circuit is controlled so that the superheat of the gas refrigerant ejected from the compressor reaches a specified superheat. Accordingly, the refrigerant injected into the compressor through the intermediate injection circuit becomes saturated, thereby preventing the compressor from being damaged.

[0003] In the refrigeration device described in Japanese Patent Publication No. 2010-60179, gas is injected into the intermediate pressure part of the compressor, thereby controlling the discharge pipe temperature. However, from the perspective of energy saving, there is room for improvement. That is, if gas refrigerant is injected into the compressor, the motive power of the compressor will increase, so there is room for improvement from the perspective of energy saving. Summary of the invention

[0004] An object of the present invention is to provide a refrigeration device, an environment forming device and a refrigeration method which can inject a refrigerant into a midway point of a compression process in a compressor and can achieve energy saving.

[0005] The refrigeration device of the present invention comprises: a main circuit provided with a compressor, a condenser, a subcooler, an expansion mechanism and an evaporator, and circulating a refrigerant; a first injection flow path branching from the main circuit at a position located on the downstream side relative to the condenser, and injecting the refrigerant into the compressor through the subcooler at a midway point of the compression process; a first injection regulating valve arranged in the first injection flow path at a position located on the upstream side relative to the subcooler; a first valve control unit controlling the first injection regulating valve so that the superheat of the refrigerant injected into the compressor through the first injection flow path reaches a target superheat; a receiving unit receiving a refrigeration requirement; and a target superheat control unit setting the target superheat to a first value when the refrigeration requirement received by the receiving unit is a first refrigeration requirement, and setting the target superheat to a second value higher than the first value when the refrigeration requirement received by the receiving unit is a second refrigeration requirement which is a refrigeration requirement lower than the first refrigeration requirement.

[0006] The environment forming device of the present invention comprises: an environment chamber; and the refrigeration device for cooling the environment chamber.

[0007] The refrigeration method of the present invention uses a refrigeration device, the refrigeration device comprising: a main circuit provided with a compressor, a condenser, a subcooler, an expansion mechanism and an evaporator, and circulating a refrigerant; a first injection flow path branching from the main circuit at a position located on the downstream side relative to the condenser, and injecting the refrigerant into the compressor through the subcooler in the middle of the compression process; a first injection regulating valve arranged at a position located on the upstream side relative to the subcooler in the first injection flow path; and a receiving unit. The refrigeration method performs the following steps: receiving a refrigeration request degree by the receiving unit; setting a target superheat degree to a first value when the refrigeration request degree received by the receiving unit is a first refrigeration request degree, and setting the target superheat degree to a second value higher than the first value when the refrigeration request degree received by the receiving unit is a second refrigeration request degree that is lower than the first refrigeration request degree; and controlling the first injection regulating valve so that the superheat degree of the refrigerant injected into the compressor through the first injection flow path reaches the target superheat degree.

[0008] According to the present invention, refrigerant can be injected into a midway portion of a compression process in a compressor, thereby achieving energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram showing the structure of the refrigeration device according to the first embodiment.

[0010] Figure 2It is a schematic diagram showing the configuration of a refrigeration device according to a modified example of the first embodiment.

[0011] Figure 3 is a schematic diagram showing a control device including a controller of the refrigeration device.

[0012] Figure 4 This is a diagram for explaining the relationship between the cooling requirement and the target superheat degree.

[0013] Figure 5 This is a diagram for explaining the relationship between the cooling requirement and the target superheat degree.

[0014] Figure 6 This is a diagram for explaining the relationship between the cooling requirement and the target superheat degree.

[0015] Figure 7 This is a diagram for explaining a control flow of the first flow rate regulating valve in the refrigeration device.

[0016] Figure 8 It is a schematic diagram showing the structure of a refrigeration device according to a second embodiment.

[0017] Fig. 9 It is a schematic diagram showing the configuration of a refrigeration apparatus according to a modified example of the second embodiment.

[0018] Fig.10 is a schematic diagram showing a control device including a controller of the refrigeration device.

[0019] Fig.11 This is a diagram for explaining a control flow of the first flow rate regulating valve in the refrigeration device.

[0020] Fig.12 This is a diagram for explaining a control flow of the second flow rate regulating valve in the refrigeration device.

[0021] Fig.13 It is a schematic diagram showing an environment forming device according to the third embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0023] (First embodiment)

[0024] like Figure 1 As shown, the refrigeration device 10 according to the first embodiment includes a main circuit 15 in which a refrigerant is sealed and a first injection flow path 16 connected to the main circuit 15. The refrigerant may be a low GWP (Global Warming Potential) refrigerant such as R-449A or R-448A.

[0025] The main circuit 15 is provided with a compressor 1, a condenser 2, a subcooler 12, an expansion mechanism 3 and an evaporator 4 in sequence. The refrigerant circulates in the main circuit 15 by the operation of the compressor 1, thereby performing a vapor compression refrigeration cycle. The refrigeration device 10 can be used to cool the air in a freezer and / or a cold storage, or can also be used to generate cooling water in a refrigerator. Alternatively, the refrigeration device 10 can also be used in an environment forming device such as an environmental test device that provides a temperature environment of a specified temperature. In addition, in the present embodiment, the refrigeration device 10 is used in a freezer.

[0026] The compressor 1 is responsible for the compression step of the refrigeration cycle, and is constructed in a manner of sucking in and compressing the refrigerant. The compressor 1 includes, for example, a scroll type, a screw type, or other compression mechanism, and is constructed so that the compression mechanism is driven by a motor with a constant speed. In addition, the compressor 1 may also be constructed so that the speed of the motor can be adjusted using an inverter. In addition, the compressor 1 may also be a structure including one unit compressor, or alternatively, may be a structure in which two unit compressors of different capacities are connected in parallel.

[0027] The condenser 2 is responsible for the condensation step of the refrigeration cycle, and is configured to condense the refrigerant discharged from the compressor 1 by exchanging heat with a cooling medium such as air, water or refrigerant.

[0028] The expansion mechanism 3 is responsible for the expansion step of the refrigeration cycle, and is configured to expand the liquid refrigerant condensed in the condenser 2. When the subcooler 12 functions, the refrigerant flowing into the expansion mechanism 3 passes through the subcooler 12 and becomes further subcooled.

[0029] The expansion mechanism 3 is formed of, for example, an electronic expansion valve. Therefore, by adjusting the valve opening, the flow rate of the liquid refrigerant flowing through the supercooler 12 and the evaporator 4 in the main circuit 15 can be arbitrarily changed.

[0030] The evaporator 4 is responsible for the evaporation step of the refrigeration cycle, and is configured to evaporate the liquid refrigerant that has been reduced in pressure by the expansion mechanism 3 by exchanging heat with air. The evaporator 4 cools the air supplied into the freezer.

[0031] The first injection flow path 16 branches from the main circuit 15 at a position on the downstream side relative to the condenser 2. That is, one end of the first injection flow path 16 is connected to the main circuit 15 between the condenser 2 and the expansion mechanism 3. Figure 1 In the embodiment, one end of the first injection flow path 16 is connected to the main circuit 15 between the condenser 2 and the subcooler 12. Figure 2 As shown, the main circuit 15 may also be connected between the subcooler 12 and the expansion mechanism 3 .

[0032] The other end of the first injection flow path 16 is connected to a midway portion of the process in which the refrigerant in the compressor 1 is compressed. That is, in the compressor 1, the refrigerant is compressed in a compression space (not shown). The first injection flow path 16 is connected so as to open to the compression space in the middle of the compression process. Therefore, the refrigerant flowing through the first injection flow path 16 is injected into the compression space in the middle of the compression in the compressor 1.

[0033] The first flow regulating valve 11 (first injection regulating valve) is disposed in the first injection flow path 16. The first flow regulating valve 11 is formed of an electronic expansion valve. Therefore, by adjusting the opening of the first flow regulating valve 11, the flow rate of the refrigerant flowing in the first injection flow path 16 can be adjusted.

[0034] The first injection flow path 16 passes through the subcooler 12 on the downstream side of the first flow regulating valve 11. Therefore, in the subcooler 12, heat exchange is performed between the liquid refrigerant flowing in the main circuit 15 and the liquid refrigerant flowing in the first injection flow path 16. Accordingly, in the first injection flow path 16, the liquid refrigerant whose temperature is lowered by being decompressed by the first flow regulating valve 11 is heated by the liquid refrigerant in the main circuit 15 and evaporates. On the other hand, the liquid refrigerant in the main circuit 15 is cooled and becomes a subcooled state.

[0035] The first injection flow path 16 is provided with an inlet temperature detector 22 for detecting the temperature of the refrigerant flowing into the subcooler 12 and an outlet temperature detector 23 for detecting the temperature of the refrigerant flowing out of the subcooler 12. The inlet temperature detector 22 and the outlet temperature detector 23 each output a signal indicating the detected temperature.

[0036] The main circuit 15 is provided with a discharge pipe temperature detector 21 for detecting the discharge pipe temperature of the compressor 1 (the temperature of the refrigerant discharged from the compressor 1). The discharge pipe temperature detector 21 outputs a signal indicating the detected temperature.

[0037] The signals outputted by the detectors 22, 23, and 21 are inputted to the controller 100. The controller 100 is formed by a microcomputer or the like having a CPU for executing arithmetic processing, a ROM for storing a processing program and data, and a RAM for temporarily storing data. By executing the processing program stored in the controller 100, Figure 3 As shown, the controller 100 can be made to function as a receiving unit 101 , a target superheat control unit 102 , a superheat calculation unit 103 , a first valve control unit 104 , and an expansion control unit 105 .

[0038] The receiving unit 101 repeatedly receives the cooling requirement at every designated time and temporarily stores the received cooling requirement. The cooling requirement is generated by the generator 120, and the cooling requirement generated by the generator 120 is input to the receiving unit 101. In addition, in the example shown in the figure, the generator 120 is configured independently of the controller 100, but the generator 120 of the cooling requirement may also be a function of the controller 100.

[0039] The generator 120 repeatedly receives signals from the sensor 121 for detecting the temperature inside the freezer, the input device 122 for inputting the set value of the temperature inside the freezer, etc., for example, at each specified time, and calculates the refrigeration requirement each time. The refrigeration requirement is a value obtained by de-dimensionalizing the refrigeration load in the freezer, for example, calculated based on the difference between the detected value and the set value of the temperature inside the freezer. Therefore, the greater the difference between the detected temperature inside the freezer and the set value of the temperature inside the freezer, the greater the refrigeration requirement. Since the refrigeration requirement may change from moment to moment, the generator 120 outputs the refrigeration requirement at each specified time.

[0040] The target superheat control unit 102 sets a target superheat which is a target value of the superheat of the refrigerant injected into the compressor 1 through the first injection flow path 16. The target superheat control unit 102 sets the value of the target superheat when the received refrigeration request degree is the first refrigeration request degree to the first value. In addition, when the received refrigeration request degree is the second refrigeration request degree which is lower than the first refrigeration request degree, the target superheat control unit 102 sets the target superheat to the second value which is higher than the first value.

[0041] In addition, if Figure 4 As shown in FIG. 1 , the target superheat may include not only a region where the target superheat becomes higher as the cooling requirement becomes lower, but also a region where the target superheat becomes a constant value regardless of the cooling requirement. Figure 5 As shown in , the target superheat degree may also be set to be higher as the cooling requirement degree becomes lower in the entire range from the minimum value to the maximum value of the cooling requirement degree. Figure 6 As shown, the target superheat can also be set to increase in a step-like manner as the cooling requirement decreases. In these cases, since the target superheat gradually increases as the cooling requirement value decreases, the smaller the cooling requirement value is, the smaller the subcooling degree generated by the subcooler 12 (closer to the saturation temperature).

[0042] The superheat calculation unit 103 derives the difference between the temperature detected by the outflow side temperature detector 23 and the temperature detected by the inflow side temperature detector 22 as the superheat of the refrigerant injected into the compressor 1 through the first injection flow path 16. That is, in the first injection flow path 16, the liquid refrigerant (liquid refrigerant flowing into the subcooler 12) after being decompressed by the first flow control valve 11 is in a saturated state or a state close to a saturated state. Therefore, the temperature difference between the temperature of the gas refrigerant flowing out of the subcooler 12 and the temperature of the liquid refrigerant flowing into the subcooler 12 is equivalent to the superheat of the refrigerant injected into the compressor 1. In addition, it is inferred that the refrigerant injected into the compressor 1 through the first injection flow path 16 is completely gasified. However, in an area with a small superheat such as the case of the lowest superheat, the injected refrigerant may also contain liquid refrigerant.

[0043] The superheat of the injected refrigerant may also be calculated by a method other than this method. For example, it may be calculated using the detection values ​​of a temperature detector (outflow side temperature detector 23) and a pressure detector (not shown) arranged on the downstream side of the subcooler 12 in the first injection flow path 16.

[0044] The first valve control unit 104 controls the first flow regulating valve 11 in such a manner that the superheat of the gas refrigerant derived by the superheat calculation unit 103 reaches the target superheat. That is, if the opening of the first flow regulating valve 11 is reduced, the flow rate of the refrigerant flowing in the first injection flow path 16 is reduced. Accordingly, in the subcooler 12, the refrigerant is placed in a further superheated state, and the superheat of the injected refrigerant is further increased. On the other hand, if the opening of the first flow regulating valve 11 is increased, the flow rate of the refrigerant flowing in the first injection flow path 16 is increased. Accordingly, in the subcooler 12, the refrigerant is placed in a less superheated state, and the superheat of the injected refrigerant is further reduced. Therefore, by adjusting the opening of the first flow regulating valve 11, the superheat of the gas refrigerant can be brought close to the target superheat.

[0045] When controlling the first flow regulating valve 11, the first valve control unit 104 controls the first flow regulating valve 11 with reference to the detection value of the discharge pipe temperature detector 21. That is, if the flow rate of the refrigerant injected into the compressor 1 through the first injection flow path 16 is reduced, the cooling effect of the compressor 1 is reduced, and accordingly, the temperature of the gas refrigerant discharged from the compressor 1 is also likely to become high. Therefore, by controlling the first flow regulating valve 11 while referring to the discharge pipe temperature, it is possible to suppress an excessive increase in the discharge pipe temperature. That is, by controlling the first flow regulating valve 11 while monitoring the discharge pipe temperature by the first valve control unit 104, an excessive increase in the discharge pipe temperature caused by a reduction in the refrigerant injection flow rate to the compressor 1 is avoided, and the power of the compressor 1 is reduced by reducing the refrigerant injection flow rate.

[0046] The expansion control means 105 adjusts the opening degree of the expansion mechanism 3 according to the cooling request degree received by the receiving unit 101. That is, the expansion control means 105 adjusts the flow rate of the refrigerant flowing into the evaporator 4 according to the cooling request degree.

[0047] In addition, the refrigeration device 10 may further include an evaporation temperature detector for detecting the temperature (evaporation temperature) of the refrigerant flowing into the evaporator 4, and the expansion control unit 105 may adjust the expansion mechanism 3 according to the evaporation temperature in addition to the cooling requirement.

[0048] Here, a refrigeration method using the refrigeration device 10 having the above-described configuration will be described.

[0049] After the target temperature of the internal temperature is set and the operation of the refrigeration device 10 starts, the controller 100 receives the detection value of the discharge pipe temperature detector 21, that is, the discharge pipe temperature, and receives the refrigeration requirement generated by the generator 120. In addition, the controller 100 also receives the detection value of the inlet side temperature detector 22 and the detection value of the outlet side temperature detector 23. The expansion control unit 105 of the controller 100 adjusts the opening of the expansion mechanism 3 based on the received refrigeration requirement. That is, based on the refrigeration requirement, the target opening or target evaporation temperature of the expansion mechanism 3 is set, and the expansion control unit 105 adjusts the opening of the expansion mechanism 3 based on these target values. Accordingly, in the subcooler 12, a refrigerant flow rate corresponding to the refrigeration requirement is obtained. In addition, when the target evaporation temperature is set, an evaporation temperature corresponding to the refrigeration requirement is obtained in the evaporator 4.

[0050] In addition, if Figure 7As shown, the controller 100 determines whether the received ejection pipe temperature is lower than the management reference temperature range (step ST12). The management reference temperature range is a pre-set temperature range, and the controller 100 controls the ejection pipe temperature in such a way that the ejection pipe temperature converges within the temperature range. If the judgment of step ST12 is "No", the process transfers to step ST13 to perform the target ejection pipe temperature control. In this control, if the detection value of the ejection pipe temperature detector 21 is within the management reference temperature range, the opening of the first flow control valve 11 is maintained. On the other hand, if the detection value of the ejection pipe temperature detector 21 exceeds the management reference temperature range, the first flow control valve 11 is controlled in such a way that the opening of the first flow control valve 11 becomes larger. Accordingly, the ejection pipe temperature is adjusted to be below the management reference temperature range.

[0051] When the received discharge pipe temperature is lower than the management reference temperature range, the process proceeds to step ST14, and the target superheat control unit 102 sets the target superheat. That is, the receiving unit 101 repeatedly receives the cooling request at each designated time, and the target superheat control unit 102 derives the target superheat corresponding to the received cooling request each time the cooling request is received.

[0052] On the other hand, the superheat calculation unit 103 calculates the superheat of the refrigerant injected into the compressor 1 through the first injection flow path 16 using the signals from the inlet side temperature detector 22 and the outlet side temperature detector 23. Then, the target superheat control is performed (step ST15). That is, the target superheat control is performed on the condition that the discharge pipe temperature of the compressor 1 does not exceed the threshold value.

[0053] In the target superheat control, the first valve control unit 104 controls the first flow regulating valve 11 in such a manner that the superheat of the refrigerant calculated by the superheat calculation unit 103 approaches the target superheat set in step ST14. At this time, when the received refrigeration requirement is the first refrigeration requirement, the target superheat is set to the first value, and when the received refrigeration requirement is the second refrigeration requirement lower than the first refrigeration requirement, the target superheat is set to the second value higher than the first value. Therefore, when the cooling load is small and the value of the refrigeration requirement is small, the target superheat is further increased. Therefore, the opening of the first flow regulating valve 11 is reduced, and the flow rate of the refrigerant injected into the compressor 1 in the middle of the compression process is further reduced, thereby helping to reduce the power of the compressor 1.

[0054] And, while the target superheat control is being performed, the process returns to step ST12 again to monitor the discharge pipe temperature, and the opening control of the first flow control valve 11 is performed again as needed (step ST13). For example, since the target superheat is increased if the refrigeration demand decreases, the opening of the first flow control valve 11 becomes smaller, and the discharge pipe temperature tends to rise. However, by performing the target discharge pipe temperature control again (step ST13), the discharge pipe temperature can be adjusted within the management reference temperature range. Therefore, even if the refrigerant gas injection amount is reduced in step ST15, the discharge pipe temperature is prevented from rising excessively.

[0055] As described above, in the present embodiment, since the first injection flow path 16 passes through the subcooler 12, the refrigerant flowing in the main circuit 15 can be subcooled by the refrigerant flowing in the first injection flow path 16. Moreover, the first injection flow path 16 is a flow path for injecting the refrigerant into the middle part of the compression process in the compressor 1. Therefore, even in the case where the refrigerant flows from the main circuit 15 to the first injection flow path 16, the refrigerant can be circulated in the main circuit 15 without reducing the flow rate to the evaporator 4. In addition, the flow rate of the refrigerant flowing in the first injection flow path 16 can be changed by changing the opening of the first flow regulating valve 11, thereby changing the degree of subcooling of the refrigerant passing through the subcooler 12 in the main circuit 15. Therefore, the refrigeration capacity can be adjusted according to the change in the degree of subcooling.

[0056] On the other hand, by controlling the first flow control valve 11, the superheat of the refrigerant injected into the compressor 1 through the first injection flow path 16 also changes. When controlling the first flow control valve 11, the first valve control unit 104 controls the first flow control valve 11 so that the superheat of the refrigerant reaches the target superheat. As the target superheat, when the refrigeration request received by the receiving unit 101 is the first refrigeration request, a first value is assigned. In addition, when the received refrigeration request is the second refrigeration request which is lower than the first refrigeration request, a second value higher than the first value is assigned as the target superheat. That is, the target superheat is set as follows: the target superheat in the case of a relatively low refrigeration request (the second refrigeration request) is higher than the target superheat in the case of a relatively high refrigeration request (the first refrigeration request). Therefore, the first flow control valve 11 is controlled to have a smaller opening when the refrigeration request is relatively low than when the target superheat is maintained at a constant value. According to this, the flow rate of the refrigerant injected into the compressor 1 through the first injection flow path 16 during compression is further reduced. Therefore, compared with the case where the target superheat is maintained at a constant value, the injection flow rate can be further reduced, and the work (power) of the compressor 1 can be further reduced. Therefore, when the cooling demand is relatively low, the power of the compressor 1 can be further reduced, and energy saving can be achieved.

[0057] In addition, in the present embodiment, when the superheat of the refrigerant is controlled to the target superheat, the condition is that the discharge pipe temperature of the compressor 1 does not exceed the threshold value. That is, the target discharge pipe temperature control (step ST13) takes precedence over the target superheat control (step ST15). Therefore, when the cooling demand is relatively low, the discharge pipe temperature can be prevented from excessively rising, thereby achieving energy saving while suppressing adverse effects on the compressor 1.

[0058] (Second embodiment)

[0059] Figure 8 The second embodiment is shown. Note that the same components as those of the first embodiment are denoted by the same reference numerals and their detailed descriptions are omitted.

[0060] In the second embodiment, a second injection flow path 17 is added. The second injection flow path 17 is a flow path for injecting the refrigerant obtained in the condenser 2 into the middle of the compression process in the compressor 1 without passing through the subcooler 12. One end of the second injection flow path 17 is connected to a portion between the condenser 2 and the subcooler 12 in the main circuit 15. In addition, the other end of the second injection flow path 17 is connected to a portion between the subcooler 12 and the compressor 1 in the first injection flow path 16. In addition, the liquid refrigerant flowing in the second injection flow path 17 sometimes flows in a completely liquid state, but sometimes is decompressed by the second flow control valve 13 described later and becomes a gas-liquid mixed state. In addition, sometimes the liquid refrigerant flowing in the second injection flow path 17 merges with the refrigerant flowing in the first injection flow path 16, so that part or all of the liquid refrigerant is gasified.

[0061] In addition, one end of the second injection flow path 17 may not be connected to the portion between the condenser 2 and the subcooler 12 in the main circuit 15. Fig. 9 As shown, one end of the second injection flow path 17 may be connected to a portion between the subcooler 12 and the expansion mechanism 3 in the main circuit 15 .

[0062] The second flow regulating valve 13 (second injection regulating valve) is disposed in the second injection flow path 17. The second flow regulating valve 13 is formed of an electronic expansion valve. Therefore, by adjusting the opening of the second flow regulating valve 13, the flow rate of the refrigerant flowing in the second injection flow path 17 can be adjusted.

[0063] like Fig.10 As shown in the figure, the functions of the controller 100 further include a second valve control unit 106. The second valve control unit 106 controls the second flow control valve 13 according to the detection result of the discharge pipe temperature detector 21. That is, the discharge pipe temperature is brought within the management reference temperature range by controlling the second flow control valve 13 by the second valve control unit 106. Therefore, in the second embodiment, the first valve control unit 104 is different from the first embodiment, and does not refer to the detection value of the discharge pipe temperature detector 21 when controlling the first flow control valve 11.

[0064] That is, in the second embodiment, Fig.11 The target superheat control and Fig.12 Target ejection pipe temperature control shown.

[0065] Target superheat control After the target temperature of the internal temperature is set and the operation of the refrigeration device 10 starts, the target superheat control unit 102 sets the target superheat (step ST22). That is, the receiving unit 101 receives the refrigeration requirement at each specified time, and the target superheat control unit 102 derives the target superheat corresponding to the refrigeration requirement received by the receiving unit 101. In addition, the superheat calculation unit 103 calculates the superheat of the refrigerant injected into the compressor 1 through the first injection flow path 16. Then, in the target superheat control of step ST23, the first valve control unit 104 controls the first flow regulating valve 11 in such a way that the calculated superheat of the refrigerant is close to the target superheat set in step ST22. Figures 4 to 6 As shown in FIG. 22 , the target superheat is set in such a way that the value (second value) for a low refrigeration requirement (second refrigeration requirement) is higher than the value (first value) for a high refrigeration requirement (first refrigeration requirement). Therefore, when the cooling load is small and the value of the refrigeration requirement is small, the target superheat is further increased. Therefore, the flow rate of the refrigerant injected into the compression portion of the compressor 1 is further reduced. The setting of the target superheat (ST22) and the target superheat control (ST23) are repeated each time the receiving unit 101 receives the refrigeration requirement. Therefore, as the temperature in the warehouse approaches the set temperature, the flow rate of the refrigerant injected into the compressor 1 decreases.

[0066] On the other hand, after the target temperature of the refrigerator interior is set and the operation of the refrigeration device 10 is started, Fig.12 As shown in FIG. 1 , the controller 100 receives the detection value of the discharge pipe temperature detector 21, that is, the discharge pipe temperature. The controller 100 determines whether the received discharge pipe temperature is within the management reference temperature range (step ST32). If the detection value of the discharge pipe temperature detector 21 is within the management reference temperature range, the opening of the second flow control valve 13 is maintained. For example, at the start of operation, since the discharge pipe temperature is within the management reference temperature range, the second flow control valve 13 is maintained in a closed state.

[0067] If the detected discharge pipe temperature changes and the judgment in step ST32 is "No", the target discharge pipe temperature control (ST33) is performed. In this control, when the detection value of the discharge pipe temperature detector 21 exceeds the management reference temperature range, the opening of the second flow control valve 13 is increased. On the other hand, if the detection value of the discharge pipe temperature detector 21 is lower than the management reference temperature range, the opening of the second flow control valve 13 is reduced. Accordingly, the discharge pipe temperature is adjusted within the management reference temperature range. The target discharge pipe temperature control (ST33) is repeated each time the controller 100 receives a detection signal from the discharge pipe temperature detector 21.

[0068] Therefore, in the second embodiment, since the refrigerant is injected into the portion in the middle of compression in the compressor 1 through the second injection flow path 17, the discharge pipe temperature of the compressor 1 can be lowered more effectively.

[0069] Furthermore, the second flow regulating valve 13 is controlled based on the detection result of the discharge pipe temperature detector 21, so that the second valve control unit 106 (controller 100) can adjust the refrigerant flow rate in the second injection flow path 17 independently of adjusting the subcooling degree in the subcooler 12 by adjusting the refrigerant flow rate flowing in the first injection flow path 16. Therefore, the refrigerant flow rate can be made appropriate using the second injection flow path 17.

[0070] In addition, in the target superheat control (ST23), the first flow regulating valve 11 may be controlled in such a manner that the injection of the refrigerant flowing from the first injection flow path 16 to the compressor 1 is stopped. That is, when the refrigeration requirement received by the receiving unit 101 is a refrigeration requirement lower than the second refrigeration requirement, that is, the third refrigeration requirement, the refrigerant injection flow rate through the first injection flow path 16 is reduced. Therefore, the discharge pipe temperature of the compressor 1 is likely to rise. In this case, since the target discharge pipe temperature control (ST33) performs the injection of the refrigerant into the compressor 1 through the second injection flow path 17, the injection of the refrigerant from the first flow regulating valve 11 side through the first injection flow path 16 may also be stopped. At this time, since the compressor 1 is cooled efficiently, it also helps to reduce the power of the compressor 1.

[0071] In this case, the target superheat control unit 102 may also set the target superheat value in such a manner that the target superheat value gradually increases as the value of the cooling demand decreases. For example, the target superheat value may be set in such a manner that it changes linearly or curvilinearly. In this manner, even when the injection of refrigerant from the first flow control valve 11 side through the first injection flow path 16 is stopped, the occurrence of unstable control of the subcooling degree of the subcooler 12 can be prevented.

[0072] Description of other structures, functions, and effects will be omitted, and the description of the first embodiment can be applied to the second embodiment.

[0073] (Third embodiment)

[0074] Fig.13 The third embodiment is shown. Note that the same components as those of the first or second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0075] The third embodiment is an example in which the refrigeration device 10 is applied to an environment forming device 50 such as an environmental testing device. The refrigeration device 10 may be any of the refrigeration devices in the first embodiment and the second embodiment.

[0076] The environment forming device 50 has an environment chamber 51, and the environment chamber 51 is adjusted to a specified temperature environment. The environment forming device 50 also has an air conditioning chamber 52 for generating temperature-regulated air, and the evaporator 4 of the refrigeration device 10 is arranged in the air conditioning chamber 52. That is, the refrigeration device 10 is configured so as to cool the environment chamber 51.

[0077] In the air conditioning room 52, a heater 54 for heating air and a blower 55 for blowing the temperature-adjusted air to the environment room 51 are arranged on the downstream side of the evaporator 4. A sensor 121 for detecting the indoor temperature is provided in the environment room 51. The input device 122 is used to input the set temperature of the temperature in the environment room 51. The environment forming device 50 may be a device that can set a wide range of temperatures such as a sub-zero temperature area, a normal temperature area, or a high temperature area, and has a program operation function that changes the temperature stepwise or continuously between a plurality of set temperatures.

[0078] The generator 120 calculates the cooling requirement using the temperature detected by the sensor 121 and the set temperature from the input device 122 .

[0079] The output of the heater 54 is controlled based on the detected temperature of the sensor 121 and the set temperature from the input device 122. That is, the specified supercooling degree is obtained by controlling the expansion mechanism 3 of the refrigeration device 10, and the specified refrigeration function is exerted. However, since the detected temperature of the sensor 121 is sometimes lower than the set temperature, in this case, the indoor temperature is fine-tuned by the heater 54. Therefore, if the supercooling of the refrigeration device 10 can be suppressed, not only the power of the refrigeration device 10 can be suppressed, but also the power of the heater 54 can be suppressed. In this regard, when the refrigeration demand is small, the refrigeration capacity is reduced by reducing the refrigerant injection flow rate using the first injection flow path 16, so that the power of the heater 54 can also be suppressed, and further energy saving can be achieved. In addition, by controlling the change of the target superheat degree through the target superheat control unit 102, both the tracking property to the set temperature and the energy saving after the temperature is reached can be achieved. Therefore, it is particularly suitable for executing a program operation in which the temperature changes stepwise or continuously between multiple set temperatures.

[0080] In addition, descriptions of other structures, functions, and effects are omitted, and the descriptions of the first or second embodiment can be applied to the third embodiment.

[0081] In order to describe the present invention, the present invention is appropriately and fully described above with reference to the accompanying drawings and through the embodiments, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, as long as the modified embodiments or improved embodiments implemented by those skilled in the art do not deviate from the level of the protection scope of the claims recorded in the claims, the modified embodiments or improved embodiments can be interpreted as being included in the protection scope of the claims.

[0082] Here, the above-mentioned embodiments will be briefly described.

[0083] (1) The refrigeration device according to the embodiment includes: a main circuit provided with a compressor, a condenser, a subcooler, an expansion mechanism, and an evaporator, and circulating a refrigerant; a first injection flow path branching from the main circuit at a position located on the downstream side relative to the condenser, and injecting the refrigerant into the compressor through the subcooler in the middle of the compression process; a first injection regulating valve arranged in the first injection flow path at a position located on the upstream side relative to the subcooler; a first valve control unit controlling the first injection regulating valve so that the superheat of the refrigerant injected into the compressor through the first injection flow path reaches a target superheat; a receiving unit receiving a refrigeration requirement; and a target superheat control unit setting the target superheat to a first value when the refrigeration requirement received by the receiving unit is a first refrigeration requirement, and setting the target superheat to a second value higher than the first value when the refrigeration requirement received by the receiving unit is a second refrigeration requirement lower than the first refrigeration requirement.

[0084] In the refrigeration device, since the first injection flow path passes through the subcooler, the refrigerant flowing in the main circuit is subcooled by the refrigerant flowing in the first injection flow path. Furthermore, since the first injection flow path is a flow path for injecting the refrigerant into the compressor in the middle of the compression process, even when the refrigerant flows from the main circuit to the first injection flow path, the refrigerant can be circulated in the main circuit without reducing the flow rate to the evaporator. In addition, since the flow rate of the refrigerant flowing in the first injection flow path can be changed by changing the opening of the first injection regulating valve, thereby changing the subcooling degree of the refrigerant passing through the subcooler in the main circuit, the refrigeration capacity can be adjusted according to the change in the subcooling degree.

[0085] On the other hand, the superheat of the refrigerant injected into the compressor through the first injection flow path also changes. When controlling the first injection regulating valve, the first valve control unit controls the first injection regulating valve so that the superheat of the refrigerant reaches the target superheat. When the refrigeration requirement received by the receiving unit is the first refrigeration requirement, the target superheat control unit assigns a first value as the target superheat. In addition, when the received refrigeration requirement is a refrigeration requirement lower than the first refrigeration requirement, that is, a second refrigeration requirement, a second value higher than the first value is assigned as the target superheat. That is, the target superheat is set so that the target superheat in the case of a relatively low refrigeration requirement (the second refrigeration requirement) is higher than the target superheat in the case of a relatively high refrigeration requirement (the first refrigeration requirement). Therefore, it is controlled so that the opening of the first injection regulating valve is smaller in the case of a relatively low refrigeration requirement than in the case of maintaining the target superheat at a constant value. Therefore, the flow rate of the refrigerant injected into the compressor through the first injection flow path at the midpoint of the compression process is further reduced. Therefore, compared with the case where the target superheat is maintained at a constant value, the injection flow rate can be further reduced, so the work (power) of the compressor can be further reduced. Therefore, when the cooling demand is relatively low, the power of the compressor can be further reduced, which can achieve energy saving.

[0086] (2) In the refrigeration device, the first valve control unit may control the first injection regulating valve on the condition that the discharge pipe temperature of the compressor does not exceed a threshold value, so that the superheat of the refrigerant reaches the target superheat.

[0087] In this technical solution, when the superheat of the refrigerant is controlled to the target superheat, the condition is that the discharge pipe temperature of the compressor does not exceed the threshold value. In other words, the discharge pipe temperature control takes precedence over the target superheat control. Therefore, when the cooling demand is relatively low, the discharge pipe temperature can be prevented from excessively rising, thereby achieving energy saving while suppressing adverse effects on the compressor.

[0088] (3) The refrigeration device may further include a second injection flow path that branches from the main circuit at a position downstream of the condenser and injects the refrigerant obtained from the condenser into a portion in the middle of the compression process in the compressor.

[0089] In this aspect, by injecting the refrigerant into the middle of the compression process in the compressor through the second injection flow path, the discharge pipe temperature of the compressor can be more effectively lowered.

[0090] (4) The refrigeration device may also include: a second injection regulating valve, which is arranged in the second injection flow path and can adjust the flow rate of the refrigerant; an outlet pipe temperature detector, which detects the outlet pipe temperature of the compressor; and a second valve control unit, which controls the second injection regulating valve according to the detection result of the outlet pipe temperature detector.

[0091] In this technical solution, the second injection regulating valve is controlled according to the detection result of the discharge pipe temperature detector, so that the refrigerant flow rate (second injection flow rate) in the second injection flow path can be adjusted independently of the adjustment of the subcooling degree in the subcooler of the first injection flow path. Therefore, the refrigerant flow rate can be made appropriate using the second injection flow path.

[0092] (5) The target superheat control unit may set the value of the target superheat so that the target superheat gradually increases as the value of the cooling request received by the receiving unit decreases.

[0093] In this technical solution, since the target superheat gradually increases as the value of the refrigeration requirement decreases, the first injection regulating valve is controlled in such a way that the refrigerant flow rate (first injection flow rate) in the first injection flow path gradually decreases. Therefore, as the value of the refrigeration requirement decreases, the subcooling degree generated by the subcooler is made smaller (closer to the saturation temperature), and the refrigeration capacity of the evaporator can be reduced. Therefore, in the case of a small refrigeration load, etc., an appropriate refrigeration capacity can be exerted, and further energy saving can be achieved.

[0094] (6) The refrigeration device may also include: a second injection flow path that branches from the main circuit at a position on the downstream side relative to the condenser, and injects the refrigerant obtained from the condenser into the middle of the compression process in the compressor. In this case, the first valve control unit may also control the first injection regulating valve to stop the injection of the refrigerant flowing from the first injection flow path to the compressor when the refrigeration requirement received by the receiving unit is a refrigeration requirement lower than the second refrigeration requirement, that is, a third refrigeration requirement.

[0095] In this technical solution, the first injection regulating valve is controlled in such a manner that the refrigerant flow rate (first injection flow rate) in the first injection flow path gradually decreases as the value of the refrigeration requirement becomes lower, and when the received refrigeration requirement is the third refrigeration requirement, the injection of the refrigerant from the first injection flow path to the compressor is stopped (the first injection is stopped). That is, the injection of the refrigerant from the first injection flow path to the compressor can be stopped (the first injection is stopped) after the refrigerant flow rate (first injection flow rate) in the first injection flow path is gradually reduced. Therefore, when the first injection is stopped, the unstable control of the subcooling degree in the subcooler can be prevented from occurring. Moreover, if the second injection regulating valve is functioning (the second injection is functioning), the rise in the temperature of the discharge pipe of the compressor can be suppressed by injecting refrigerant into the compressor.

[0096] (7) The environment forming device includes: an environment chamber; and the refrigeration device, which is used to cool the environment chamber.

[0097] (8) The refrigeration method according to the embodiment uses a refrigeration device, the refrigeration device comprising: a main circuit provided with a compressor, a condenser, a subcooler, an expansion mechanism, and an evaporator, and circulating a refrigerant; a first injection flow path branching from the main circuit at a position located on the downstream side relative to the condenser, and injecting the refrigerant into the compressor through the subcooler at a midway point of the compression process; a first injection regulating valve arranged at a position located on the upstream side relative to the subcooler in the first injection flow path; and a receiving unit. The refrigeration method performs the following steps: receiving a refrigeration request degree by the receiving unit; setting a target superheat degree to a first value when the refrigeration request degree received by the receiving unit is a first refrigeration request degree, and setting the target superheat degree to a second value higher than the first value when the refrigeration request degree received by the receiving unit is a second refrigeration request degree that is lower than the first refrigeration request degree; and controlling the first injection regulating valve so that the superheat degree of the refrigerant injected into the compressor through the first injection flow path reaches the target superheat degree.

[0098] As described above, the refrigerant can be injected into the middle of the compression process in the compressor, and energy saving can be achieved.

Claims

1. A refrigeration device, characterized in that include: A main circuit is provided with a compressor, a condenser, a subcooler, an expansion mechanism and an evaporator, and circulates the refrigerant; a first injection flow path that branches from the main circuit at a position downstream of the condenser and injects the refrigerant into a midway portion of a compression process in the compressor via the subcooler; a first injection regulating valve disposed in the first injection flow path at a position on the upstream side relative to the subcooler; a first valve control unit that controls the first injection regulating valve so that the superheat of the refrigerant injected into the compressor through the first injection flow path reaches a target superheat; Reception department, receiving refrigeration requirements; as well as A target superheat control unit sets the target superheat to a first value when the refrigeration requirement degree received by the receiving unit is a first refrigeration requirement degree, and sets the target superheat to a second value higher than the first value when the refrigeration requirement degree received by the receiving unit is a second refrigeration requirement degree which is lower than the first refrigeration requirement degree.

2. The refrigeration device according to claim 1, characterized in that: The first valve control unit controls the first injection regulating valve on the condition that the discharge pipe temperature of the compressor does not exceed a threshold value so that the superheat of the refrigerant reaches the target superheat.

3. The refrigeration device according to claim 1, characterized in that Also includes: The second injection flow path branches off from the main circuit at a position on the downstream side with respect to the condenser, and injects the refrigerant obtained from the condenser into a portion in the middle of a compression process in the compressor.

4. The refrigeration device according to claim 3, characterized in that Also includes: a second injection regulating valve, arranged in the second injection flow path, capable of regulating the flow rate of the refrigerant; A discharge pipe temperature detector for detecting the temperature of the discharge pipe of the compressor; as well as The second valve control unit controls the second injection regulating valve based on the detection result of the discharge pipe temperature detector.

5. The refrigeration device according to claim 1, characterized in that: The target superheat control unit sets a value of the target superheat so that the target superheat gradually increases as a value of the cooling request degree received by the receiving unit decreases.

6. The refrigeration device according to claim 5, characterized in that Also includes: The second injection flow path branches from the main circuit at a position downstream of the condenser, and injects the refrigerant obtained from the condenser into a midway portion of the compression process in the compressor, wherein: When the refrigeration requirement degree received by the receiving unit is a third refrigeration requirement degree which is lower than the second refrigeration requirement degree, the first valve control unit controls the first injection regulating valve to stop the injection of the refrigerant flowing from the first injection flow path to the compressor.

7. An environment forming device, characterized in that include: Environmental chamber; as well as The refrigeration device according to any one of claims 1 to 6, used for cooling the environmental room.

8. A refrigeration method, characterized in that Using a refrigeration device, the refrigeration device comprising: A main circuit is provided with a compressor, a condenser, a subcooler, an expansion mechanism and an evaporator, and circulates the refrigerant; a first injection flow path that branches from the main circuit at a position downstream of the condenser and injects the refrigerant into a midway portion of a compression process in the compressor via the subcooler; a first injection regulating valve disposed in the first injection flow path at a position upstream of the subcooler; and Reception Department, The refrigeration method is performed as follows: The receiving unit receives a cooling requirement; When the refrigeration request degree received by the receiving unit is a first refrigeration request degree, the target superheat degree is set to a first value, and when the refrigeration request degree received by the receiving unit is a second refrigeration request degree which is lower than the first refrigeration request degree, the target superheat degree is set to a second value which is higher than the first value; The first injection regulating valve is controlled so that the superheat of the refrigerant injected into the compressor through the first injection flow path reaches the target superheat.

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