Refrigeration device, environment forming device, and refrigeration method

Abstract

The invention provides a refrigeration device, an environment forming device and a refrigeration method. This refrigeration device is provided with: a main circuit in which a compressor, a condenser, an expansion valve, and an evaporator are provided, and which circulates a refrigerant; a bypass flow path which is provided with a flow control valve, branches from the main circuit, and sucks the refrigerant into the compressor without passing through the evaporator after the temperature of the refrigerant liquefied in the condenser is reduced by the flow control valve; an expansion control unit which controls the expansion valve according to the refrigeration requirement degree; a degree of superheat control unit that controls the flow regulating valve such that the degree of superheat corresponding to the saturation temperature of the suction pressure of the compressor reaches a target value; and a changing unit that changes the target value of the degree of superheat. Accordingly, the compressor can be stably driven by injection through the suction port of the bypass flow path, and the refrigeration capacity of the evaporator can be adjusted.

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 Utility Model Publication No. 6-4560, a refrigeration device including a refrigeration circuit is known, and the refrigeration circuit has a bypass flow path for injecting refrigerant into the suction port of the compressor. The bypass flow path is connected to the main circuit of the refrigeration circuit provided with a compressor, a condenser, an expansion valve and an evaporator. The bypass flow path is used to return a part of the high-pressure liquid refrigerant obtained in the condenser to the suction port of the compressor by bypassing the expansion valve and the evaporator after the part becomes low temperature and low pressure. By allowing the refrigerant flowing through the bypass flow path to be sucked into the compressor, the temperature of the discharge pipe of the compressor can be reduced.

[0003] As in the refrigeration device disclosed in Japanese Utility Model Publication No. 6-4560, in a structure where the bypass flow path is connected to the main circuit, the compressor can be protected because the temperature of the discharge pipe of the compressor can be reduced. On the other hand, if a constant flow of refrigerant continues to flow to the bypass flow path, a specified flow of refrigerant will flow to the bypass flow path even when the compressor does not need to be cooled. Therefore, the amount of refrigerant flowing to the evaporator is reduced accordingly, and the refrigeration capacity exerted in the evaporator is reduced. Therefore, the compressor is sometimes over-protected at the expense of refrigeration capacity. 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 that can stably drive a compressor by using suction port injection of a bypass flow path and can adjust the refrigeration capacity of an evaporator.

[0005] A refrigeration device according to one aspect of the present invention includes: a main circuit, which is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates a refrigerant; a bypass flow path, which is provided with a flow regulating valve and branches from a position between the condenser and the expansion valve in the main circuit, and after the temperature of the refrigerant liquefied in the condenser is reduced by the flow regulating valve, the refrigerant is sucked into the compressor without passing through the evaporator; an expansion control unit, which controls the expansion valve according to the refrigeration requirement; a superheat control unit, which controls the flow regulating valve so that the superheat relative to the saturation temperature equivalent to the suction pressure of the compressor reaches a target value; and a changing unit, which changes the target value of the superheat.

[0006] Another aspect of the present invention relates to an environment forming device comprising: an environment chamber; and the refrigeration device, which is used to cool the environment chamber.

[0007] Another aspect of the present invention relates to a refrigeration method using a refrigeration device, which includes: a main circuit, which is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates a refrigerant; a bypass flow path, which is provided with a flow regulating valve and branches from a position between the condenser and the expansion valve in the main circuit, and after the temperature of the refrigerant liquefied in the condenser is reduced by the flow regulating valve, the refrigerant is sucked into the compressor without passing through the evaporator; and a receiving unit, the refrigeration method performs the following steps: the receiving unit receives a refrigeration requirement; the expansion valve is controlled according to the refrigeration requirement received by the receiving unit; the target value of the superheat relative to the saturation temperature equivalent to the suction pressure of the compressor is changed according to the refrigeration requirement or the opening of the expansion valve; and the flow regulating valve is controlled so that the superheat reaches the changed target value.

[0008] According to the present invention, the compressor can be stably driven by suction port injection using the bypass flow path, and the refrigeration capacity of the evaporator can be adjusted. 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 2 is a schematic diagram showing a control device including a controller of the refrigeration device.

[0011] Figure 3 This is a diagram for explaining the relationship between the internal temperature and the target value of the superheat degree.

[0012] Figure 4 It is a diagram for explaining the control flow of the refrigeration device.

[0013] Figure 5 It is a schematic diagram showing the configuration of a refrigeration device according to a modified example of the first embodiment.

[0014] Figure 6 It is a schematic diagram showing the structure of a refrigeration device according to a second embodiment.

[0015] Figure 7 It is a schematic diagram showing the configuration of a refrigeration apparatus according to a modified example of the second embodiment.

[0016] Figure 8 is a schematic diagram showing a control device including a controller of the refrigeration device.

[0017] Fig. 9 It is a schematic diagram showing an environment forming device according to the third embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0019] (First embodiment)

[0020] 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 bypass 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.

[0021] The main circuit 15 is provided with a compressor 1, a condenser 2, an expansion valve 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 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.

[0022] 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 a compression mechanism such as a scroll type or a screw type, and a motor that drives the compression mechanism. In addition, the compressor 1 is configured to drive the motor at a constant speed, but, instead, it can also be configured to be able to adjust the speed of the motor using an inverter. In addition, the compressor 1 can also be a structure including one unit compressor, or alternatively, it can be a structure in which two unit compressors of the same or different capacities are connected in parallel.

[0023] 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.

[0024] The expansion valve 3 is responsible for the expansion step of the refrigeration cycle, and is configured to expand the liquid refrigerant condensed in the condenser 2 .

[0025] The expansion valve 3 is formed of, for example, an electronic expansion valve. Therefore, by adjusting the valve opening of the expansion valve 3, the flow rate of the liquid refrigerant flowing through the evaporator 4 in the main circuit 15 can be arbitrarily changed.

[0026] The evaporator 4 is responsible for the evaporation step of the refrigeration cycle, and is configured to evaporate the liquid refrigerant that has become low pressure in the expansion valve 3 by exchanging heat with air. That is, the evaporator 4 cools the air supplied into the freezer.

[0027] The bypass 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 bypass flow path 16 is connected to the main circuit 15 between the condenser 2 and the expansion valve 3. The other end of the bypass flow path 16 is connected to the main circuit 15 between the evaporator 4 and the compressor 1. Therefore, the refrigerant flowing through the bypass flow path 16 merges with the refrigerant evaporated in the evaporator 4 and is sucked into the compressor 1.

[0028] The bypass flow passage 16 is provided with a flow control valve 11. The flow control valve 11 is formed of an electronic expansion valve. Therefore, by adjusting the opening of the flow control valve 11, the flow rate of the refrigerant flowing in the bypass flow passage 16 can be adjusted.

[0029] A bypass temperature detector 21 for detecting the temperature of the refrigerant flowing in the bypass flow passage 16 is provided in the bypass flow passage 16 on the downstream side of the flow rate regulating valve 11. The bypass temperature detector 21 outputs a signal indicating the detected temperature.

[0030] The main circuit 15 is provided with a suction temperature detector 22 for detecting the temperature of the refrigerant sucked into the compressor 1. The suction temperature detector 22 outputs a signal indicating the detected temperature.

[0031] The signals outputted by the detectors 21 and 22 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 2 As shown, the controller 100 can be made to function as a receiving unit 101 , an expansion control unit 102 , a superheat degree calculation unit 103 , a superheat degree control unit 104 , and a changing unit 105 .

[0032] 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.

[0033] The generator 120, for example, repeatedly receives signals from a sensor 121 for detecting the internal temperature (i.e., the temperature of the cooled room in the freezer), an input device 122 for inputting a set value of the internal temperature, etc. at each specified time, and calculates the refrigeration requirement each time. The refrigeration requirement is a value obtained by dedimensionalizing the refrigeration load in the freezer, for example, calculated based on the difference between the detected value and the set value of the internal temperature. Therefore, the greater the difference between the detected value of the internal temperature and the set value of the internal temperature, 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.

[0034] The expansion control unit 102 adjusts the opening of the expansion valve 3 according to the received refrigeration requirement every time the receiving unit 101 receives the refrigeration requirement. That is, the expansion control unit 102 controls the expansion valve 3 in such a manner that the opening of the expansion valve 3 becomes larger as the refrigeration requirement becomes higher, and controls the expansion valve 3 in such a manner that the opening of the expansion valve 3 becomes smaller as the refrigeration requirement becomes lower. Accordingly, the flow rate of the refrigerant flowing through the evaporator 4 can be set to a flow rate corresponding to the refrigeration requirement, and thus, a refrigeration capacity corresponding to the refrigeration requirement can be obtained.

[0035] The superheat calculation unit 103 derives the difference between the temperature detected by the suction temperature detector 22 and the temperature detected by the bypass temperature detector 21 as the superheat of the refrigerant sucked into the compressor 1. That is, in the bypass flow path 16, the liquid refrigerant after being decompressed by the flow control valve 11 is in a saturated state or a state close to a saturated state. The liquid refrigerant rises in temperature by merging with the gas refrigerant evaporated in the evaporator 4 and is sucked into the compressor 1. Therefore, the temperature difference between the temperature of the gas refrigerant sucked into the compressor 1 and the temperature of the liquid refrigerant on the downstream side of the flow control valve 11 in the bypass flow path 16 corresponds to the superheat of the refrigerant sucked into the compressor 1. That is, the difference between the temperature of the gas refrigerant sucked into the compressor 1 and the temperature of the liquid refrigerant on the downstream side of the flow control valve 11 in the bypass flow path 16 is the superheat relative to the "saturation temperature corresponding to the suction pressure of the compressor 1".

[0036] In addition, the superheat of the refrigerant sucked into the compressor 1 may be calculated by a method other than this method. For example, a pressure detector (not shown) for detecting the pressure of the refrigerant sucked into the compressor 1 may be provided, and the superheat of the refrigerant sucked into the compressor 1 may be calculated using the saturated vapor temperature corresponding to the detected pressure and the detected temperature of the suction temperature detector 22.

[0037] The superheat control unit 104 controls the flow regulating valve 11 in such a manner that the superheat of the gas refrigerant derived by the superheat calculation unit 103 reaches a target value. That is, if the opening of the flow regulating valve 11 is reduced, the flow rate of the refrigerant flowing in the bypass flow path 16 is reduced, and therefore, the ratio of the flow rate of the refrigerant passing through the bypass flow path 16 to the flow rate of the refrigerant passing through the evaporator 4 becomes smaller. In this case, the superheat of the refrigerant is further increased. On the other hand, if the opening of the flow regulating valve 11 is increased, the flow rate of the refrigerant flowing in the bypass flow path 16 is increased, and therefore, the ratio of the flow rate of the refrigerant passing through the bypass flow path 16 to the flow rate of the refrigerant passing through the evaporator 4 becomes larger. In this case, the superheat of the refrigerant is further reduced. Therefore, by adjusting the opening of the flow regulating valve 11, the superheat of the gas refrigerant can be brought close to the target value.

[0038] The changing unit 105 changes the target value of the superheat of the refrigerant sucked into the compressor 1 according to the refrigeration request received by the receiving unit 101. The changing unit 105 sets the target value of the superheat to a first value when the received refrigeration request is a first refrigeration request, and sets the target value of the superheat to a second value lower than the first value when the received refrigeration request is a second refrigeration request which is lower than the first refrigeration request.

[0039] like Figure 3 As shown in FIG. 1 , the superheat target value is set with an upper limit value and a lower limit value, and the superheat target value takes a value between the upper limit value and the lower limit value according to the cooling requirement. The superheat target value is set to be higher as the cooling requirement becomes higher, and to be lower as the cooling requirement becomes lower. In the case where the cooling requirement is shown as a value from 0% to 100%, when the cooling requirement is 100%, the superheat target value is set to the upper limit value, and when the cooling requirement is 0%, the superheat target value is set to the lower limit value.

[0040] The upper limit of the superheat target value includes an area that changes according to the temperature in the freezer (or refrigerator) (the internal temperature (i.e., the temperature of the cooled room in the freezer)) and an area that is constant regardless of the internal temperature, but is not limited to this. It can also be set so that the upper limit of the superheat target value becomes higher as the internal temperature increases over the entire temperature range that the internal temperature can take. Alternatively, the upper limit of the superheat target value is set to the same value over the entire temperature range that the internal temperature can take. In addition, in a case where the refrigeration device 10 is configured as a refrigerator, the "internal temperature" can be replaced by the temperature of the coolant introduced into the evaporator 4.

[0041] The lower limit of the superheat target value is constant throughout the temperature range that the internal temperature can take, but it can also be set to include a region where the lower limit of the superheat target value becomes higher as the internal temperature increases. In addition, it can also be set so that the lower limit of the superheat target value becomes higher as the internal temperature increases throughout the temperature range that the internal temperature can take.

[0042] Here, a refrigeration method using the refrigeration device 10 having the above-described configuration will be described.

[0043] After the target temperature of the internal temperature is set and the operation of the refrigeration device 10 is started, Figure 4 As shown, the controller 100 receives the cooling requirement generated by the generator 120 (ST11). In addition, the controller 100 receives the suction temperature, which is the detection value of the suction temperature detector 22, and receives the bypass temperature, which is the detection value of the bypass temperature detector 21 (ST12). The cooling requirement, suction temperature, and bypass temperature are repeatedly received by the controller 100 at each specified time.

[0044] The superheat degree calculation unit 103 of the controller 100 calculates the superheat degree of the refrigerant sucked into the compressor 1 using the suction temperature (ie, the detection value of the suction temperature detector 22) and the bypass temperature (ie, the detection value of the bypass temperature detector 21) (ST13).

[0045] The expansion control unit 102 of the controller 100 adjusts the opening of the expansion valve 3 based on the received refrigeration requirement (ST14). The refrigeration requirement changes all the time, and the generator 120 outputs the refrigeration requirement at each specified time. Therefore, the expansion control unit 102 adjusts the opening of the expansion valve 3 whenever receiving the refrigeration requirement. In this case, the expansion control unit 102 controls the expansion valve 3 so that the higher the refrigeration requirement, the larger the opening of the expansion valve 3, and the lower the refrigeration requirement, the smaller the opening of the expansion valve 3. Accordingly, since the refrigerant of the flow rate corresponding to the refrigeration requirement flows through the evaporator 4, the refrigeration capacity corresponding to the refrigeration requirement is exerted in the evaporator 4.

[0046] The cooling requirement is also used to set a target value of the superheat of the refrigerant sucked into the compressor 1. That is, the changing unit 105 changes the target value of the superheat of the refrigerant sucked into the compressor 1 according to the cooling requirement received by the receiving unit 101 (ST15). At this time, the superheat target value is changed so that the higher the cooling requirement is, the higher the superheat target value is, and the lower the superheat target value is, the lower the cooling requirement is.

[0047] The superheat control unit 104 controls the flow control valve 11 (ST16) in such a manner that the superheat reaches the changed target value. Specifically, when the refrigeration requirement is high, the superheat target value is changed to be higher than the current value, and therefore, the superheat control unit 104 controls the flow control valve 11 in such a manner that the opening of the flow control valve 11 becomes smaller. That is, when the refrigeration requirement is high, the opening of the flow control valve 11 is reduced. As a result, the flow rate of the refrigerant flowing through the bypass flow path 16 is reduced. Along with this, the flow rate of the refrigerant flowing into the evaporator 4 can be increased. That is, the opening of the expansion valve 3 is set by the expansion control unit 102 to a value corresponding to the refrigeration requirement, but as the opening of the flow control valve 11 is reduced, the flow rate of the refrigerant flowing through the evaporator 4 can be increased. Therefore, compared with the case where the target value of the superheat is fixed, the refrigeration capacity exerted by the evaporator 4 can be increased.

[0048] On the other hand, when the cooling demand is low, the superheat target value is changed to be lower than the current value. Thus, the superheat control unit 104 controls the flow control valve 11 in such a way that the valve opening of the flow control valve 11 is further increased. That is, when the cooling demand is low, the opening of the expansion valve 3 has been reduced, and the circulation flow of the main circuit 15 has decreased, so it is difficult to obtain the cooling effect of the compressor 1. In response to this, the flow control valve 11 is controlled in such a way that the valve opening of the flow control valve 11 becomes larger, so that the flow rate of the refrigerant flowing through the bypass flow path 16 can be increased. According to this, the flow rate of the refrigerant sucked into the compressor 1 can be increased, so that the cooling effect of the compressor 1 can be improved. On the other hand, with the increase of the refrigerant flow rate of the bypass flow path 16, the flow rate of the refrigerant flowing into the evaporator 4 is further reduced under the opening of the expansion valve 3 controlled by the expansion control unit 102. Therefore, compared with the case where the target value of the superheat is fixed, the refrigeration capacity exerted by the evaporator 4 can be further reduced.

[0049] As described above, in this embodiment, the expansion control unit 102 adjusts the expansion valve 3 according to the refrigeration requirement. Therefore, the flow rate of the refrigerant flowing through the evaporator 4 is adjusted according to the refrigeration requirement. Therefore, in the evaporator 4, the refrigeration capacity corresponding to the refrigeration requirement can be exerted. On the other hand, a part of the refrigerant condensed in the condenser 2 is sucked into the compressor 1 through the bypass flow path 16 without passing through the evaporator 4. Therefore, the cooling effect of the compressor 1 (the effect of reducing the discharge pipe temperature) can be obtained, and on the other hand, the refrigeration capacity exerted in the evaporator 4 may be reduced. However, since the target value of the superheat of the refrigerant sucked into the compressor 1, which is the control target of the flow control valve 11 of the bypass flow path 16, can be changed by the change unit 105, the refrigerant flow rate flowing through the bypass flow path 16 can be adjusted. Therefore, according to the change amount of the target value of the superheat, the valve opening of the flow control valve 11 is adjusted, thereby changing the reduction amount of the refrigerant flow rate flowing through the evaporator 4 according to the refrigeration requirement. Therefore, the cooling capacity of the evaporator 4 can be adjusted while adjusting the discharge pipe temperature of the compressor 1, and the imbalance between the protection of the compressor 1 and the cooling capacity can be suppressed.

[0050] Furthermore, since the target value of the superheat is changed according to the refrigeration requirement, the valve opening of the flow control valve 11 can be adjusted to correspond to the refrigeration requirement. That is, the expansion valve 3 is adjusted to an opening corresponding to the refrigeration requirement, and the flow control valve 11 is adjusted to obtain the target value of the superheat corresponding to the refrigeration requirement. Therefore, the opening of the expansion valve 3 is adjusted in a manner to exert the refrigeration capacity corresponding to the refrigeration requirement, and the refrigerant flow of the evaporator 4 obtained by adjusting the expansion valve 3 also changes with the adjustment of the valve opening of the flow control valve 11. Therefore, even if the refrigerant flow to the evaporator 4 decreases with the refrigerant flowing to the bypass flow path 16, the amount of reduction in refrigeration capacity can be adjusted by adjusting the valve opening of the flow control valve 11.

[0051] In addition, in the present embodiment, the change unit 105 reduces the target value of the superheat when the cooling demand is low. That is, when the cooling demand is low, the target value of the superheat is reduced, and the valve opening of the flow control valve 11 is further increased. Therefore, compared with the case where the superheat target value is fixed, the flow rate of the refrigerant flowing through the bypass flow path 16 (suction injection flow rate, the flow rate injected into the suction port of the compressor 1 after flowing through the bypass flow path 16) increases. On the other hand, when the cooling demand is low, the opening of the expansion valve 3 becomes smaller in order to reduce the cooling capacity exerted by the evaporator 4, so the flow rate of the refrigerant circulating in the main circuit 15 becomes less. Therefore, there is a tendency that it is difficult to obtain the cooling effect of the compressor 1 with the reduction of the refrigerant circulation flow rate. However, since the suction injection flow rate is increased, it is possible to avoid a situation where it is difficult to obtain the cooling effect of the compressor 1. In addition, since the target value of the superheat is not adjusted based on the discharge pipe temperature of the compressor 1, the opening of the flow control valve 11 is adjusted regardless of whether the discharge pipe temperature rises or not. Therefore, the refrigeration capacity of the evaporator 4 can be adjusted more appropriately according to the degree of refrigeration demand.

[0052] Furthermore, as the valve opening of the flow control valve 11 further increases, the refrigerant flow rate flowing through the bypass flow path 16 further increases, and therefore, the refrigerant flow rate of the evaporator 4 can be further reduced by setting the opening of the expansion valve 3 to a value corresponding to the cooling requirement by the expansion control unit 102. Therefore, the cooling capacity of the evaporator 4 can be further reduced. Therefore, compared with the case where the target value of the superheat degree is fixed, the cooling capacity of the evaporator 4 adjusted according to the cooling requirement can be further reduced. Therefore, when the state of low cooling requirement continues, it is possible to suppress the occurrence of excessive cooling capacity.

[0053] In addition, in the present embodiment, in the area where the temperature in the storage is at a low temperature, the upper limit value of the target value of the superheat is set to become smaller as the temperature in the storage becomes lower. Therefore, the cooling effect of the compressor 1 can be further improved. For example, at a certain refrigeration requirement, when the temperature in the storage is low, the evaporation temperature needs to be further lowered compared to the case where the temperature in the storage is high relative to the same refrigeration requirement, and therefore, there is a tendency that the opening of the expansion valve 3 is reduced. Therefore, the lower the temperature in the storage, the less the refrigerant circulation flow rate, and therefore it is difficult to obtain the cooling effect of the compressor 1. In response to this, the flow control valve is further opened by setting it in a manner that the upper limit value of the target value of the superheat becomes smaller as the temperature in the storage becomes lower. Accordingly, even when the expansion valve 3 is in a state where the opening is reduced, the cooling effect of the compressor 1 can be easily obtained.

[0054] In addition, in the present embodiment, the changing means 105 changes the target value of the superheat corresponding to the saturation temperature of the suction pressure of the compressor 1 according to the cooling demand, but instead, the target value of the superheat may be changed according to the opening of the expansion valve 3. In this case, the target value of the superheat changes according to the opening of the expansion valve 3, and the valve opening of the flow control valve 11 is adjusted accordingly. That is, since the opening of the expansion valve 3 is adjusted to the opening corresponding to the cooling demand, the valve opening of the flow control valve 11 is adjusted to the opening corresponding to the cooling demand by changing the target value of the superheat according to the opening of the expansion valve 3. In addition, in this case, the changing means 105 reduces the target value of the superheat when the opening of the expansion valve 3 is small. That is, when the opening of the expansion valve 3 is small, the suction pressure to the compressor 1 decreases, and therefore, the discharge pipe temperature of the compressor 1 is likely to increase accordingly. In this case, the target value of the superheat is lowered by the changing unit 105, so the superheat control unit 104 controls the flow control valve 11 so as to increase the valve opening of the flow control valve 11. Therefore, the flow rate (suction port injection flow rate) of the refrigerant flowing through the bypass flow path 16 increases, so that the increase in the discharge pipe temperature can be suppressed.

[0055] In addition, in the above-described embodiment, the upper limit of the superheat target value changes according to the temperature in the storage room, but it is not limited to this. For example, a region where the upper limit of the superheat target value decreases as the outlet temperature of the evaporator 4 or the evaporation temperature of the refrigerant decreases instead of the temperature in the storage room may be set. In addition, it may be set so that the upper limit of the superheat target value decreases as the outlet temperature of the evaporator 4 or the evaporation temperature of the refrigerant decreases over the entire range that the outlet temperature of the evaporator 4 or the evaporation temperature of the refrigerant can take. In these cases, the cooling effect of the compressor 1 can also be easily obtained.

[0056] In addition, the upper limit value of the superheat target value may be set to decrease as the detected temperature of the bypass temperature detector 21 (i.e., the temperature on the outlet side of the flow control valve 11 in the bypass flow path 16) decreases instead of the internal temperature. That is, since the detected temperature of the bypass temperature detector 21 depends on the suction pressure to the compressor 1 (the low pressure in the main circuit 15), the detected temperature of the bypass temperature detector 21 decreases as the opening of the expansion valve 3 decreases. Therefore, if the upper limit value of the superheat target value is set so as to decrease as the detected temperature of the bypass temperature detector 21 decreases, the same effect as the case where the upper limit value of the superheat target value decreases as the opening of the expansion valve 3 decreases can be obtained. Therefore, the cooling effect of the compressor 1 can be easily obtained.

[0057] In addition, multiple temperatures including the internal temperature, the outlet temperature of the evaporator 4, the evaporation temperature of the refrigerant and the detection temperature of the bypass temperature detector 21 can be referred to and set as follows: if the value obtained as a result of performing a specified processing (for example, an average processing) on ​​the multiple temperatures decreases, the upper limit value of the superheat target value becomes smaller.

[0058] In addition, in the present embodiment, the superheat calculation unit 103 derives the difference between the temperature detected by the suction temperature detector 22 and the temperature detected by the bypass temperature detector 21 as the superheat of the refrigerant sucked into the compressor 1, but the present invention is not limited thereto. Figure 5 As shown, the bypass temperature detector 21 may be omitted and a pressure detector 31 for detecting the pressure of the refrigerant sucked into the compressor 1 may be provided. Furthermore, the superheat calculation unit 103 derives the difference between the temperature detected by the suction temperature detector 22 and the saturated vapor temperature corresponding to the pressure detected by the pressure detector 31 as the superheat of the sucked refrigerant.

[0059] (Second embodiment)

[0060] like Figure 6 As shown, the refrigeration device 10 according to the second embodiment includes a hot gas bypass flow path 17. In addition, the same reference numerals are attached to the same components as those of the first embodiment, and detailed descriptions thereof are omitted.

[0061] The hot gas bypass flow path 17 is a flow path that allows a portion of the refrigerant ejected from the compressor 1 to be sucked into the compressor 1 without passing through the condenser 2, the expansion valve 3, and the evaporator 4. One end of the hot gas bypass flow path 17 is connected between the compressor 1 and the condenser 2 in the main circuit 15. The other end of the hot gas bypass flow path 17 is connected to a portion between the evaporator 4 and the compressor 1 in the main circuit 15.

[0062] The hot gas bypass passage 17 is provided with a hot gas valve 12 having a mechanical expansion valve. Therefore, the hot gas valve 12 is always open in a state set to a specified opening degree. Figure 7 and Figure 8 As shown, the hot gas valve 12 may be controlled to be opened and closed by the controller 100. That is, the hot gas valve 12 may be controlled to be opened when the suction pressure of the compressor 1 is likely to be below the set pressure, such as when the expansion valve 3 is closed (or the opening is very small), and closed in other cases. The set pressure may be a pressure set as a range in which the compressor 1 can operate stably and specified according to the design conditions of the compressor 1.

[0063] In the present embodiment, the hot gas control unit 106 of the controller 100 controls the hot gas valve 12 in such a manner that the suction pressure of the compressor 1 does not become less than the set pressure. That is, if the opening of the expansion valve 3 becomes smaller, the suction pressure of the compressor 1 decreases accordingly. Therefore, if the expansion valve 3 is closed (or the opening is made very small) in order to reduce the refrigeration capacity as much as possible, the suction pressure of the compressor 1 is excessively reduced and may not be able to operate stably. In response to this, when the suction pressure is about to become less than the set pressure, the hot gas control unit 106 opens the hot gas valve 12. Accordingly, since the hot gas is sucked into the compressor 1 through the hot gas bypass flow path 17, the suction pressure can be prevented from becoming less than the set pressure. Therefore, the refrigeration capacity of the evaporator 4 can be reduced as much as possible while ensuring the stable operation of the compressor 1.

[0064] If the hot gas valve 12 is opened, the superheat of the refrigerant sucked into the compressor 1 increases, and accordingly, the superheat control unit 104 further increases the valve opening of the flow control valve 11 so that the superheat approaches the target value. Therefore, even if the hot gas valve 12 is opened, the superheat of the sucked refrigerant does not become too high.

[0065] In addition, the hot gas valve 12 may also be formed by an electronic expansion valve. In this case, the hot gas control unit 106 is configured to control the opening of the hot gas valve 12. For example, the hot gas control unit 106 may be linked with the opening control of the expansion valve 3 by the expansion control unit 102, or may be controlled to adjust the opening of the hot gas valve 12 according to the cooling requirement. In this case, the hot gas control unit 106 controls the hot gas valve 12 to open at least when the expansion valve 3 is closed. In this way, the cooling capacity of the evaporator 4 can be reduced as much as possible. In addition, when the hot gas valve 12 is controlled according to the cooling requirement, the hot gas valve 12 is controlled in such a way that the opening of the hot gas valve 12 is further increased as the cooling requirement becomes lower. In this way, the suction pressure of the compressor 1 can be ensured. In addition, when a pressure sensor 31 for detecting the pressure of the refrigerant sucked into the compressor 1 is provided, the hot gas valve 12 may be controlled in such a way that the suction pressure of the compressor 1 does not drop below a specified pressure.

[0066] In addition, descriptions of other structures, functions, and effects are omitted, and the descriptions of the first embodiment can be applied to the second embodiment.

[0067] (Third embodiment)

[0068] Fig. 9 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.

[0069] 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.

[0070] The environment forming device 50 includes an environment chamber 51, and adjusts the environment chamber 51 to a predetermined temperature environment. The environment forming device 50 further includes an air conditioning chamber 52 for generating temperature-regulated air, and the evaporator 4 of the refrigeration device 10 is disposed in the air conditioning chamber 52.

[0071] In the air-conditioning room 52, a heater 54 for heating air and a blower 55 for blowing the temperature-adjusted air to the environmental room 51 are arranged on the downstream side of the evaporator 4. A sensor 121 for detecting the indoor temperature is provided in the environmental room 51. The input device 122 is used to input the set temperature of the temperature in the environmental room 51. In addition, in this embodiment, the "inside temperature" in the first and second embodiments can be replaced by "indoor temperature". That is, the sensor 121 detects the air temperature of the room to which the air cooled by the evaporator 4 is supplied.

[0072] The generator 120 calculates the cooling requirement using the temperature detected by the sensor 121 and the set temperature from the input device 122 .

[0073] The output of the heater 54 is controlled based on the detection temperature of the sensor 121 and the set temperature from the input device 122. That is, the expansion valve 3 of the refrigeration device 10 is controlled based on the refrigeration demand, so that the specified refrigeration capacity can be exerted. At this time, since the detection temperature of the sensor 121 is sometimes lower than the set temperature, the indoor temperature is finely adjusted by the heater 54. Therefore, if the overcooling of the refrigeration device 10 can be suppressed, not only the power of the refrigeration device 10 but also the power of the heater 54 can be suppressed. In this regard, when the refrigeration demand is small, since the change unit 105 reduces the target value of the superheat, the flow control valve 11 is controlled in such a way that the opening of the flow control valve 11 is further increased accordingly. With this, the flow rate of the refrigerant flowing into the evaporator 4 can be further reduced at the opening of the expansion valve 3 controlled by the expansion control unit 102. Therefore, compared with the case where the target value of the superheat is fixed, the refrigeration capacity exerted by the evaporator 4 can be further reduced, so the power of the heater 54 can also be suppressed, and further energy saving can be achieved. In addition, the heater 54 can also be omitted.

[0074] In addition, the upper limit of the target value of the superheat degree is set to be smaller as the indoor temperature becomes lower. Therefore, when the cooling demand is 100%, the lower the indoor temperature, the smaller the opening of the expansion valve 3 tends to be, and the flow control valve 11 is further opened. According to this, the refrigerant flow rate flowing to the evaporator 4 is further reduced, so the cooling capacity of the evaporator 4 can be further reduced. Therefore, since the output of the heater 54 can be suppressed, energy saving of the environment forming device 50 can be achieved.

[0075] 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.

[0076] (Other embodiments)

[0077] The embodiments disclosed this time are merely illustrative in all respects and should not be construed as limiting. The present invention is not limited to the embodiments described above, and various changes and improvements can be made without departing from the gist of the invention.

[0078] Here, the above-mentioned embodiments will be briefly described.

[0079] (1) The refrigeration device involved in the embodiment includes: a main circuit, which is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates a refrigerant; a bypass flow path, which is provided with a flow control valve and branches from a position between the condenser and the expansion valve in the main circuit, and after the temperature of the refrigerant liquefied in the condenser is reduced by the flow control valve, the refrigerant is sucked into the compressor without passing through the evaporator; an expansion control unit, which controls the expansion valve according to the refrigeration demand; a superheat control unit, which controls the flow control valve so that the superheat relative to the saturation temperature equivalent to the suction pressure of the compressor reaches a target value; and a changing unit, which changes the target value of the superheat.

[0080] In the refrigeration device, the expansion control unit adjusts the expansion valve of the main circuit according to the refrigeration requirement. Therefore, the flow rate of the refrigerant flowing through the evaporator is adjusted according to the refrigeration requirement. Therefore, in the evaporator, the refrigeration capacity corresponding to the refrigeration requirement can be exerted. On the other hand, since a part of the refrigerant condensed in the condenser is sucked into the compressor through the bypass flow path without passing through the evaporator, the cooling effect of the compressor (the effect of reducing the temperature of the discharge pipe) can be obtained, and the refrigeration capacity exerted in the evaporator may be reduced. However, since the valve opening of the flow control valve provided in the bypass flow path can be adjusted, the flow rate of the refrigerant flowing through the bypass flow path can be adjusted. Moreover, the target value of the superheat of the refrigerant sucked into the compressor, which is the control target of the flow control valve, can be changed by the changing unit. Therefore, according to the change amount of the target value of the superheat, the valve opening of the flow control valve is adjusted, so that the reduction amount of the refrigerant flow rate flowing through the evaporator can be changed. Therefore, the refrigeration capacity of the evaporator can be adjusted while the compressor is stably driven, and the imbalance between the protection of the compressor and the refrigeration capacity can be suppressed.

[0081] (2) The changing means may be configured to change the target value of the degree of superheat according to the cooling requirement.

[0082] In this technical solution, since the target value of superheat is changed according to the refrigeration requirement, the valve opening of the flow control valve can be adjusted to correspond to the refrigeration requirement. That is, the expansion valve is adjusted to an opening corresponding to the refrigeration requirement, and the flow control valve is adjusted to obtain a target value of superheat corresponding to the refrigeration requirement. Therefore, the opening of the expansion valve is adjusted in a manner to exert the refrigeration capacity corresponding to the refrigeration requirement. At this time, the refrigerant flow of the evaporator obtained by adjusting the expansion valve also changes with the adjustment of the valve opening of the flow control valve. Therefore, even if the refrigerant flow to the evaporator decreases as the refrigerant flows to the bypass flow path, the amount of reduction in refrigeration capacity can be adjusted by adjusting the valve opening of the flow control valve.

[0083] (3) The changing unit may be configured to change the target value of the superheat degree according to the opening degree of the expansion valve.

[0084] In this technical solution, the target value of the superheat degree changes according to the opening degree of the expansion valve, and the valve opening degree of the flow control valve is adjusted accordingly. That is, the opening degree of the expansion valve is adjusted to an opening degree corresponding to the cooling requirement, and the refrigerant flow rate of the evaporator obtained by adjusting the expansion valve also changes with the adjustment of the valve opening degree of the flow control valve. Therefore, even if the refrigerant flow rate flowing to the evaporator decreases with the refrigerant flowing to the bypass flow path, the amount of reduction in cooling capacity can be adjusted by adjusting the valve opening degree of the flow control valve.

[0085] (4) The upper limit value of the target value of the superheat may also be set to become smaller as the temperature inside the freezer (i.e., the temperature of the cooled room in the freezer), the outlet temperature of the evaporator, the evaporation temperature of the refrigerant or the temperature on the outlet side of the flow control valve becomes lower; or, become smaller as the value obtained by performing specified processing on multiple temperatures among these temperatures becomes lower.

[0086] In this technical solution, the cooling effect of the compressor can be further improved. For example, at a certain refrigeration requirement, when the temperature inside the warehouse (i.e., the temperature of the cooled room in the freezer) is low, the evaporation temperature needs to be further lowered compared to the case where the temperature inside the warehouse is high with respect to the same refrigeration requirement, and therefore, there is a tendency for the opening of the expansion valve to be reduced. Therefore, the lower the temperature inside the warehouse, the less the refrigerant circulation flow rate tends to be, and therefore it is difficult to obtain the cooling effect of the compressor. In response to this, the flow control valve is further opened by setting the target value of the superheat so that the upper limit value becomes smaller as the temperature inside the warehouse becomes lower. Accordingly, even when the expansion valve is in a state where the opening is reduced, the cooling effect of the compressor can be easily obtained. This is also true for the case where the outlet temperature of the evaporator and the evaporation temperature of the refrigerant are reduced.

[0087] In addition, since the temperature on the outlet side of the flow control valve depends on the suction pressure to the compressor (low pressure of the refrigeration circuit), the temperature decreases as the opening of the expansion valve decreases. Therefore, if the upper limit of the target value of the superheat degree is set to decrease as the temperature decreases, the same effect as the case where the upper limit of the target value of the superheat degree decreases as the opening of the expansion valve decreases can be obtained. Therefore, the cooling effect of the compressor can be easily obtained.

[0088] (5) The refrigeration device may further include: a bypass temperature detector disposed in the bypass flow path and detecting the temperature of the refrigerant on the downstream side of the flow control valve; and a suction temperature detector disposed in the main circuit and detecting the temperature of the refrigerant sucked into the compressor. In this case, the superheat degree may also be obtained based on the temperature difference between the detection temperature of the suction temperature detector and the detection temperature of the bypass temperature detector.

[0089] The detection temperature of the bypass temperature detector is a saturation temperature equivalent to the suction pressure. Therefore, the superheat of the refrigerant sucked into the compressor can be obtained based on the temperature difference between the detection temperature of the suction temperature detector for detecting the temperature of the refrigerant sucked into the compressor where the refrigerant from the bypass flow path merges with the refrigerant after passing through the evaporator and the detection temperature of the bypass temperature detector.

[0090] (6) The refrigeration device may also include a hot gas bypass flow path, which is provided with a hot gas valve and branches from a position between the compressor and the condenser in the main circuit, so that the refrigerant compressed in the compressor is not sucked into the compressor via the evaporator; and a hot gas control unit that opens the hot gas valve so that the pressure of the refrigerant sucked into the compressor does not become lower than the set pressure.

[0091] In this technical solution, the hot gas control unit controls the hot gas valve in such a way that the suction pressure of the compressor does not fall below the set pressure. That is, if the opening of the expansion valve becomes smaller, the suction pressure of the compressor decreases accordingly. Therefore, if the expansion valve opening is made very small in order to reduce the refrigeration capacity as much as possible, the suction pressure of the compressor decreases excessively and may not be able to operate stably. In response to this, when the suction pressure is about to fall below the set pressure, the hot gas is sucked into the compressor through the hot gas bypass flow path, so that the suction pressure will not fall below the set pressure. Therefore, the refrigeration capacity can be reduced as much as possible while ensuring the stable operation of the compressor.

[0092] (7) The hot gas control unit may also control the hot gas valve according to the cooling requirement.

[0093] In this technical solution, when the refrigeration requirement is low and the expansion control unit controls the expansion valve to be opened less, the hot gas control unit can control the hot gas valve to be opened further. Therefore, when the refrigeration requirement is low, the refrigeration capacity can be reduced as much as possible. In addition, the hot gas is sucked into the compressor through the hot gas bypass flow path, so that the suction pressure will not be less than the set pressure. Therefore, the refrigeration capacity can be reduced as much as possible while ensuring the stable operation of the compressor.

[0094] (8) The environment forming device according to the above embodiment includes: an environment chamber; and the refrigeration device for cooling the environment chamber.

[0095] In the environment forming device, when the target value of the superheat is reduced in the refrigeration device, for example, the opening of the flow control valve is controlled to be further increased. Therefore, the flow rate of the refrigerant flowing into the evaporator can be further reduced. Therefore, compared with the case where the target value of the superheat is fixed, the refrigeration capacity exerted by the evaporator can be reduced.

[0096] (9) The refrigeration method involved in the embodiment uses a refrigeration device, which includes: a main circuit, which is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates the refrigerant; a bypass flow path, which is provided with a flow regulating valve and branches from a position between the condenser and the expansion valve in the main circuit, and after the temperature of the refrigerant liquefied in the condenser is reduced by the flow regulating valve, the refrigerant is sucked into the compressor without passing through the evaporator; and a receiving unit, the refrigeration method performs the following steps: the receiving unit receives a refrigeration requirement; the expansion valve is controlled according to the refrigeration requirement received by the receiving unit; the target value of the superheat relative to the saturation temperature of the suction pressure of the compressor is changed according to the refrigeration requirement or the opening of the expansion valve; and the flow regulating valve is controlled so that the superheat reaches the changed target value.

[0097] (10) In the case where the refrigeration device further includes a bypass temperature detector, which is arranged in the bypass flow path and detects the temperature of the refrigerant on the downstream side of the flow regulating valve; and an intake temperature detector, which is arranged in the main circuit and detects the temperature of the refrigerant sucked into the compressor, in the refrigeration method, the superheat can also be calculated based on the temperature difference between the detection temperature of the intake temperature detector and the detection temperature of the bypass temperature detector.

[0098] (11) In the case where the refrigeration device also includes a hot gas bypass flow path, is provided with a hot gas valve, and is branched from a position between the compressor and the condenser in the main circuit so that the refrigerant compressed in the compressor is not sucked into the compressor via the evaporator, in the refrigeration method, the hot gas valve can also be opened so that the pressure of the refrigerant sucked into the compressor does not become lower than the set pressure.

[0099] As described above, the compressor can be stably driven by the suction port injection using the bypass flow path, and the refrigeration capacity of the evaporator can be adjusted.

[0100] This application is based on Japanese patent application No. 2023-146286 filed on September 8, 2023, the contents of which are incorporated herein by reference. That is, this application claims priority to Japanese patent application (application number 2023-146286) filed on September 8, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A refrigeration device, characterized in that include: A main circuit is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates the refrigerant; A bypass flow path is provided with a flow regulating valve and branches from a position between the condenser and the expansion valve in the main circuit, wherein the flow regulating valve reduces the temperature of the refrigerant liquefied in the condenser so that the refrigerant is sucked into the compressor without passing through the evaporator; An expansion control unit controls the expansion valve according to a refrigeration requirement; a superheat control unit that controls the flow control valve so that the superheat corresponding to the saturation temperature of the suction pressure of the compressor reaches a target value; and A changing unit changes the target value of the superheat degree.

2. The refrigeration device according to claim 1, characterized in that: The changing unit changes the target value of the superheat degree according to the cooling request degree.

3. The refrigeration device according to claim 1, characterized in that: The changing unit changes the target value of the superheat degree according to the opening degree of the expansion valve.

4. The refrigeration device according to claim 1, characterized in that: The upper limit of the target value of the superheat is set to become smaller as the temperature inside the storage, the outlet temperature of the evaporator, the evaporation temperature of the refrigerant or the temperature on the outlet side of the flow control valve becomes lower; or, becomes smaller as the value obtained by performing specified processing on multiple temperatures among these temperatures becomes lower.

5. The refrigeration device according to any one of claims 1 to 4, characterized in that Also includes: a bypass temperature detector disposed in the bypass flow path and detecting the temperature of the refrigerant on the downstream side of the flow control valve; as well as The suction temperature detector is arranged in the main circuit and detects the temperature of the refrigerant sucked into the compressor, wherein: The degree of superheat is obtained based on a temperature difference between a temperature detected by the intake temperature detector and a temperature detected by the bypass temperature detector.

6. The refrigeration device according to any one of claims 1 to 4, characterized in that Also includes: a hot gas bypass flow path, provided with a hot gas valve, and branching from a position between the compressor and the condenser in the main circuit so that the refrigerant compressed in the compressor is sucked into the compressor without passing through the evaporator; as well as The hot gas control unit opens the hot gas valve so that the pressure of the refrigerant sucked into the compressor does not become less than a set pressure.

7. The refrigeration device according to claim 6, characterized in that: The hot gas control unit controls the hot gas valve according to the cooling requirement.

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

9. A refrigeration method, characterized in that Using a refrigeration device, the refrigeration device comprising: A main circuit is provided with a compressor, a condenser, an expansion valve and an evaporator, and circulates the refrigerant; a bypass flow path provided with a flow regulating valve and branching from a position between the condenser and the expansion valve in the main circuit, wherein the flow regulating valve reduces the temperature of the refrigerant liquefied in the condenser so that the refrigerant is sucked into the compressor without passing through the evaporator; and Reception Department, The refrigeration method is performed as follows: The receiving unit receives a cooling requirement; controlling the expansion valve according to the cooling demand received by the receiving unit; changing a target value of superheat relative to a saturation temperature equivalent to a suction pressure of the compressor according to the cooling demand or the opening degree of the expansion valve; The flow rate regulating valve is controlled so that the superheat degree reaches the changed target value.

10. The refrigeration method according to claim 9, characterized in that: The refrigeration device also includes: a bypass temperature detector disposed in the bypass flow path and detecting a temperature of the refrigerant on a downstream side of the flow control valve; and A suction temperature detector is arranged in the main circuit and detects the temperature of the refrigerant sucked into the compressor. In the refrigeration method, the degree of superheat is obtained based on a temperature difference between a temperature detected by the suction temperature detector and a temperature detected by the bypass temperature detector.

11. The refrigeration method according to claim 9 or 10, characterized in that: The refrigeration device also includes: A hot gas bypass flow path is provided with a hot gas valve and branches from a position between the compressor and the condenser in the main circuit so that the refrigerant compressed in the compressor is sucked into the compressor without passing through the evaporator. In the refrigeration method, the hot gas valve is opened so that the pressure of the refrigerant sucked into the compressor does not become lower than a set pressure.

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