Cooling device

Abstract

To provide a cooling device capable of suppressing increase in a cooling load for keeping an interior temperature, at the time of defrosting.SOLUTION: A cooling device 100 is equipped with a compressor 10, a condenser 20, a first expanding portion 30, a first evaporator 51 and a second evaporator 52, a four-way valve 40 that switches a flowing direction of a refrigerant between a first flowing direction and a second flowing direction, and a second expanding portion 70 that expands the refrigerant flowing out from either one of the first evaporator 51 or the second evaporator 52. The cooling device 100 is configured to be brought in a first state in which the cooling of air in an air channel 92 is performed by the second evaporator 52 along with the defrosting of the first evaporator 51, if the four-way valve 40 switches the flowing direction of the refrigerant to the first flowing direction, and to be brought in a second state in which the cooling of air in an air channel 91 is performed by the first evaporator 51 along with the defrosting of the second evaporator 52, if the four-way valve 40 switches the flowing direction of the refrigerant to the second flowing direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cooling device, and more particularly to a cooling device that removes frost from an evaporator. [Background technology]

[0002] 2. Description of the Related Art Conventionally, cooling devices that remove frost from an evaporator are known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a hot gas defrost type refrigeration and storage device (cooling apparatus) that includes a compressor, a condensation section, an expansion section, and an evaporation section, and in which a high-pressure side pipe between the compressor and the condensation section and a low-pressure side pipe between the expansion section and the evaporation section are connected by a bypass pipe. The refrigeration and storage device of Patent Document 1 is configured to perform defrosting to remove frost that has adhered to the evaporation section by supplying high-temperature, high-pressure refrigerant supplied from the compressor to the evaporation section via the bypass pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-124922 A Summary of the Invention [Problem to be solved by the invention]

[0005] The freezer-refrigerator described in the above Patent Document 1 is configured to perform defrosting to remove frost adhering to the evaporator by supplying a high-temperature, high-pressure refrigerant to the evaporator through a bypass pipe as described above. Therefore, during defrosting, the evaporator is heated by the high-temperature, high-pressure refrigerant, and the temperature around the evaporator also becomes high. Therefore, in the freezer-refrigerator described in the above Patent Document 1, in order to maintain the temperature inside the refrigerator during defrosting, it is necessary to cool the temperature around the evaporator heated by the high-temperature, high-pressure refrigerant to the temperature inside the refrigerator, and a high load of cooling is required. As a result, there is a problem that the cooling load for maintaining the temperature inside the refrigerator increases during defrosting.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a cooling device that can suppress an increase in cooling load for maintaining the temperature inside the storage unit during defrosting. [Means for solving the problem]

[0007] A cooling device according to one aspect of the present invention is a cooling device that cools a cooling space, the cooling device including: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant discharged from the compressor; a first expansion section that expands the refrigerant condensed by the condenser; and a second expansion section that is provided in an air flow path to which air that cools the cooling space is sent, Located upstream The compressor includes a first evaporator and a second evaporator that evaporate the refrigerant expanded by the first expansion section, a flow direction switching section that is provided downstream of the first expansion section and upstream of the compressor and that switches the flow direction of the refrigerant expanded by the first expansion section between a first flow direction and a second flow direction, and a second expansion section that is connected between the first evaporator and the second evaporator and that expands the refrigerant flowing out of either the first evaporator or the second evaporator, and the flow direction switching section switches the flow direction of the refrigerant expanded by the first expansion section in the first flow direction. The pressure is reduced When the flow direction of the refrigerant is switched, a first state is entered in which the frost adhering to the first evaporator provided in the air flow path for cooling the cooling space is removed during cooling of the first evaporator, and the air in the air flow path for cooling the cooling space is cooled by the second evaporator provided in the air flow path for cooling the cooling space. In this state, the flow direction switching unit causes the refrigerant expanded by the first expansion unit to flow in the second flow direction. The pressure is reduced When the flow direction of the refrigerant is switched, the second evaporator is defrosted and the first evaporator cools the air in the air flow passage, resulting in a second state.

[0008] As described above, the cooling device according to one aspect of the present invention includes a first evaporator and a second evaporator that evaporate the refrigerant expanded by the first expansion section, and a second expansion section that is connected between the first evaporator and the second evaporator and expands the refrigerant flowing out of either the first evaporator or the second evaporator. Furthermore, the flow direction switching section switches the flow direction of the refrigerant expanded by the first expansion section between the first flow direction and the second flow direction, so that the flow direction of the refrigerant flowing through the first evaporator, the second expansion section, and the second evaporator can be switched between the first flow direction and the second flow direction. In the first state, the first evaporator is defrosted, so that heat is taken from the refrigerant flowing through the first evaporator (the enthalpy of the refrigerant decreases), and therefore the temperature (enthalpy) of the refrigerant flowing out of the first evaporator decreases. Therefore, by switching the flow direction of the refrigerant flowing out of the first evaporator and flowing into the second evaporator as the first flow direction by the flow direction switching unit, when the second evaporator is cooled in the first state, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the first evaporator flows into the second evaporator that cools the air in the air flow path through the second expansion unit. As a result, the cooling capacity of the second evaporator can be improved without increasing the flow rate of the refrigerant. In addition, in the second state, the defrosting of the second evaporator removes heat from the refrigerant flowing through the second evaporator (the enthalpy of the refrigerant decreases), so the temperature (enthalpy) of the refrigerant flowing out of the second evaporator decreases. Therefore, by switching the flow direction of the refrigerant flowing out of the second evaporator and flowing into the first evaporator as the second flow direction by the flow direction switching unit, when the first evaporator is cooled in the second state, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the second evaporator flows through the second expansion unit into the first evaporator that cools the air in the air flow path. As a result, the cooling capacity of the first evaporator can be improved without increasing the flow rate of the refrigerant.Furthermore, since the high-temperature, high-pressure refrigerant supplied from the compressor is expanded by the first expansion section and then supplied to the first or second evaporator, the increase in temperature around the first and second evaporators can be suppressed when defrosting the first and second evaporators, compared to when the high-temperature, high-pressure refrigerant supplied from the compressor is supplied to the first or second evaporator. As a result, the increase in the cooling load for maintaining the temperature inside the refrigerator can be suppressed when defrosting. In addition, since the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the first evaporator (second evaporator) flows into the second evaporator (first evaporator) through the second expansion section, the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the first evaporator (second evaporator) evaporates by absorbing heat (enthalpy becomes large) when cooling the second evaporator (first evaporator). As a result, the refrigerant whose temperature (enthalpy) has decreased due to defrosting of the first evaporator (second evaporator) can be prevented from returning to the compressor in a state with a decreased temperature (enthalpy) (in liquid state) (liquid back), thereby reducing the load on the compressor caused by liquid back.

[0009] In the cooling device according to the above aspect, preferably, in a first state, the refrigerant expanded by the first expansion section is caused to flow in a first flow direction through the first evaporator, the second expansion section, the second evaporator, and the compressor in that order, thereby defrosting the first evaporator and cooling the air in the air flow path by the second evaporator, and in a second state, the refrigerant expanded by the first expansion section is caused to flow in a second flow direction through the second evaporator, the second expansion section, the first evaporator, and the compressor in that order, thereby defrosting the second evaporator and cooling the air in the air flow path by the first evaporator. With this configuration, in the first state, the refrigerant expanded by the first expansion section is caused to flow in the first flow direction through the first evaporator, the second expansion section, the second evaporator, and the compressor in this order, thereby defrosting the first evaporator and cooling the air in the air flow path by the second evaporator, so that the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the first evaporator flows through the second expansion section into the second evaporator that cools the air in the air flow path. As a result, the cooling capacity of the second evaporator can be improved without increasing the flow rate of the refrigerant. In addition, in the second state, the refrigerant expanded by the first expansion section is caused to flow in the second flow direction through the second evaporator, the second expansion section, the first evaporator, and the compressor in this order, thereby defrosting the second evaporator and cooling the air in the air flow path by the first evaporator, so that the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the second evaporator flows through the second expansion section into the first evaporator that cools the air in the air flow path. As a result, the cooling capacity of the first evaporator can be improved without increasing the flow rate of the refrigerant, and as a result, an increase in the cooling load for maintaining the temperature inside the refrigerator during defrosting can be suppressed.

[0010] In the cooling device according to the above aspect, the first expansion section is preferably configured to adjust the temperature of the refrigerant flowing into the first evaporator in the first state and the temperature of the refrigerant flowing into the second evaporator in the second state by adjusting the pressure of the refrigerant to be discharged. With this configuration, the first expansion section can adjust the temperature of the refrigerant flowing into the first evaporator in the first state and the temperature of the refrigerant flowing into the second evaporator in the second state, so that a refrigerant with a temperature according to the respective locations of the first evaporator and the second evaporator and the defrosting method can be caused to flow. As a result, the first evaporator and the second evaporator can be efficiently defrosted.

[0011] In the cooling device according to the above aspect, preferably, air is supplied to the first evaporator in the air flow path. Send Wind machine and 、 The control unit further includes a control unit that, when defrosting the first evaporator in the first state, controls the temperature of the refrigerant flowing into the first evaporator to be higher than that when cooling the refrigerant; Sending The frost on the first evaporator is removed by airflow caused by the fan. conduct With this configuration, the control unit in the first state controls the first evaporator to remove frost adhering to the first evaporator by airflow (wind pressure defrosting), thereby defrosting the first evaporator. .So As a result, in the first state Send When the second evaporator is positioned downstream of the air blown by the fan, the second evaporator can be used as a collection section that collects frost and moisture sublimated and peeled off (removed) from the first evaporator when the first evaporator is defrosted.

[0012] In the cooling device according to the above aspect, the first evaporator and the second evaporator are provided in multiple numbers, the multiple first evaporators are connected in parallel between the flow direction switching unit and the second expansion unit, and the multiple second evaporators are connected in parallel between the flow direction switching unit and the second expansion unit. With this configuration, the multiple first evaporators and the multiple second evaporators are connected in parallel between the flow direction switching unit and the second expansion unit, so that unlike the case where the multiple first evaporators and the multiple second evaporators are connected in series, refrigerant with the same flow rate and temperature flows into each of the multiple first evaporators and the multiple second evaporators. As a result, it is possible to easily control the refrigerant flow rate and refrigerant pressure during cooling of each of the multiple first evaporators and the multiple second evaporators.

[0013] In this case, preferably, the first evaporators include a first one-side evaporator and a first other-side evaporator, the second evaporators include a second one-side evaporator and a second other-side evaporator, the second expansion section includes a first one-side expansion valve and a first other-side expansion valve, the first one-side evaporator, the second one-side evaporator and the first one-side expansion valve are connected in series, and the first other-side evaporator, the second other-side evaporator and the first other-side expansion valve are connected in series. With this configuration, the refrigerant flow path between the first one-side evaporator and the second one-side evaporator and the refrigerant flow path between the first other-side evaporator and the second other-side evaporator are independently provided, so that the first one-side expansion valve and the first other-side expansion valve can individually control each refrigerant flow path. As a result, the flow rate of the refrigerant between the first one-side evaporator (the second one-side evaporator) and the first other-side evaporator (the second other-side evaporator) can be easily adjusted compared to the case where a common expansion valve is provided for the first evaporators and the second evaporators.

[0014] In the cooling device according to the above aspect, the second expansion section preferably includes a first refrigerant flow path connected to the first evaporator and the second evaporator, a second first expansion valve provided in the first refrigerant flow path and expanding the refrigerant flowing in the first flow direction in the first state, a second refrigerant flow path connected to the first evaporator and the second evaporator and bypassing the first refrigerant flow path, and a second second expansion valve provided in the second refrigerant flow path and expanding the refrigerant flowing in the second flow direction in the second state. With this configuration, the second first expansion valve and the second second expansion valve are provided to correspond to the first flow direction and the second flow direction, respectively, so that the second expansion section can be configured only with an expansion valve that allows the refrigerant to flow in only one direction without using an expansion valve that allows the refrigerant to flow in both directions. Moreover, the second first expansion valve and the second second expansion valve are provided to correspond to the first flow direction and the second flow direction, respectively. This allows the flow rate and temperature of the refrigerant to be adjusted by using a mechanical expansion valve, such as a temperature expansion valve, in the second expansion section, which detects the state of the refrigerant only in the corresponding flow direction (first flow direction and second flow direction).

[0015] In the cooling device according to the above aspect, the flow direction switching unit preferably includes a four-way valve that switches between the first state and the second state by switching the flow direction of the refrigerant expanded by the first expansion unit between the first flow direction and the second flow direction. With this configuration, the flow direction of the refrigerant expanded by the first expansion unit can be switched between the first flow direction and the second flow direction by switching the flow path inside the four-way valve. This makes it possible to suppress pressure loss compared to when the refrigerant flow direction is switched by a solenoid valve. As a result, it is possible to suppress an increase in the load on the compressor due to a decrease in the flow rate of the refrigerant caused by pressure loss. Effect of the Invention

[0016] According to the present invention, as described above, it is possible to suppress an increase in the cooling load for maintaining the temperature inside the refrigerator during defrosting. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a configuration of a refrigerant flow path of a cooling device according to a first embodiment of the present invention. [Diagram 2] 1 is a first cross-sectional view showing an air flow path of a cooling device according to a first embodiment of the present invention. [Diagram 3] 4 is a second cross-sectional view showing the arrangement of the first evaporator and the second evaporator of the cooling device according to the first embodiment of the present invention. FIG. [Figure 4] FIG. 2 is a refrigerant flow path diagram for illustrating a first state of the cooling device according to the first embodiment of the present invention. [Diagram 5] 3 is a cross-sectional view of an air flow path for illustrating a first state of the cooling device according to the first embodiment of the present invention. FIG. [Figure 6] FIG. 4 is a refrigerant flow path diagram for illustrating a second state of the cooling device according to the first embodiment of the present invention. [Figure 7] 5 is a cross-sectional view of an air flow path for illustrating a second state of the cooling device according to the first embodiment of the present invention. FIG. [Figure 8] FIG. 11 is a block diagram showing the configuration of a refrigerant flow path of a cooling device according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a refrigerant flow path diagram for illustrating a first state of a cooling device according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a refrigerant flow path diagram for illustrating a second state of the cooling device according to the second embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view illustrating the arrangement of a first evaporator and a second evaporator in a cooling device according to a first modified example of the present invention. [Figure 12] FIG. 11 is a refrigerant flow path diagram for explaining a flow direction switching portion of a cooling device according to a second modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] (First embodiment) The configuration of a cooling device 100 according to a first embodiment will be described with reference to FIGS.

[0020] The cooling device 100 is configured to cool a cooling space. Specifically, the cooling device 100 is configured to cool the cooling space to a temperature of 0°C or lower. For example, the cooling device 100 is configured to cool the cooling space to a temperature of about -20°C. The cooling device 100 is configured to cool the inside of a showcase, a refrigerator, a freezer, a warehouse, or a room, which serves as the cooling space. For example, the cooling device 100 is an ice showcase in which the top of the cooling space is open and which cools frozen foods and ice creams.

[0021] As shown in Fig. 1, the cooling device 100 includes a compressor 10. The compressor 10 is configured to compress a refrigerant. The compressor 10 is controlled by an inverter (not shown). As a result, the compressor 10 is configured to be able to adjust the flow rate of the refrigerant discharged from the compressor 10. The refrigerant is, for example, R410A, R404A, R32, carbon dioxide (CO2), or the like.

[0022] The cooling device 100 also includes a condenser 20. The condenser 20 is configured to condense the refrigerant discharged from the compressor 10. The condenser 20 is provided with a blower 21. The blower 21 is configured to send air to the condenser 20. Then, heat is transferred from the refrigerant in the condenser 20 to the air sent by the blower 21.

[0023] The cooling device 100 also includes a first expansion section 30. The first expansion section 30 includes a solenoid valve 31 and an expansion valve 32. The expansion valve 32 is configured to expand the refrigerant condensed by the condenser 20. The expansion valve 32 is configured, for example, of a needle valve. The opening degree of the expansion valve 32 is adjusted by a stepping motor (not shown) attached to the expansion valve 32. The flow rate of the refrigerant to the evaporators 51a, 51b, 52a, and 52b provided downstream is adjusted by adjusting the opening degree of the expansion valve 32.

[0024] In addition, the first expansion section 30 (expansion valve 32) is configured to adjust the pressure of the outflowing refrigerant, thereby adjusting the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) in a first state described below, and the temperature of the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) in a second state described below.

[0025] The cooling device 100 includes evaporators 51a and 51b as the first evaporator 51. The cooling device 100 includes evaporators 52a and 52b as the second evaporator 52. The evaporators 51a and 51b are configured to evaporate the refrigerant expanded by the first expansion section 30 (expansion valve 32) in a first state described below. The evaporators 52a and 52b are configured to evaporate the refrigerant expanded by the first expansion section 30 (expansion valve 32) in a second state described below. The evaporators 51a and 51b are examples of "plurality of first evaporators" in the claims, and the evaporators 52a and 52b are examples of "plurality of second evaporators" in the claims. The evaporators 51a, 51b, 52a, and 52b are examples of "first one evaporator", "first other evaporator", "second one evaporator", and "second other evaporator", respectively.

[0026] The evaporators 51a and 51b are provided in an air flow path 91 to which air to be cooled is sent, as shown in Fig. 2. The evaporators 51a and 51b are provided in parallel to each other between the four-way valve 40 and the second expansion section 70. Furthermore, the evaporators 52a and 52b are provided in an air flow path 92, as shown in Fig. 2. The evaporators 52a and 52b are provided in parallel to each other between the four-way valve 40 and the second expansion section 70.

[0027] Each of the evaporators 51a, 51b, 52a, and 52b includes a refrigerant flow path through which the refrigerant flows, and a heat transfer surface that transfers the temperature of the refrigerant. Specifically, each of the evaporators 51a, 51b, 52a, and 52b includes a plurality of flat plates arranged parallel to each other. The flat plates are made of a metal such as aluminum. The front and back surfaces of the flat plates are heat transfer surfaces. The refrigerant flow path penetrates the plurality of flat plates and is provided in a meandering manner. The heat transfer surface may be flat or may have an uneven shape. By having the heat transfer surface have an uneven shape, it is possible to easily remove frost that has adhered to the heat transfer surface.

[0028] The second evaporator 52 (evaporators 52a and 52b) is configured to collect frost and moisture removed by airflow from each of the first evaporators 51 (evaporators 51a and 51b) during defrosting by sublimation and peeling due to airflow of the first evaporator 51 (evaporators 51a and 51b) (first state described later). That is, the evaporator 52a is provided for the evaporator 51a, and is provided to serve as a collecting section that collects frost and moisture sublimated and peeled (removed) from the evaporator 51a during defrosting of the evaporator 51a. The evaporator 52a is provided on the suction port 94 side (X1 direction side) of the evaporator 51a. The evaporator 52b is provided for the evaporator 51b, and is provided to serve as a collecting section that collects frost and moisture sublimated and peeled (removed) from the evaporator 51b during defrosting of the evaporator 51b. The evaporator 52b is provided on the suction port 94 side (X1 direction side) of the evaporator 51b. Note that defrosting refers to removing frost attached to the heat transfer surfaces of the evaporators 51a, 51b, 52a, and 52b.

[0029] In the first embodiment, the second evaporator 52 (evaporators 52a and 52b) is provided in a downstream air flow path 92 to which air is sent from the first evaporator 51 (evaporators 51a and 51b) when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. The second evaporator 52 (evaporators 52a and 52b) is configured to cool the air sent from the first evaporator 51 (evaporators 51a and 51b) to a temperature at the time of cooling by the first evaporator 51 (evaporators 51a and 51b) when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state.

[0030] As shown in FIG. 3, in a direction (X direction) in which the first evaporator 51 (evaporators 51a and 51b) and the second evaporator 52 (evaporators 52a and 52b) are adjacent to each other and in a direction (Y direction) intersecting the vertical direction (Z direction), the evaporators 51a and 52a are arranged adjacent to the evaporators 51b and 52b, respectively.

[0031] The cooling device 100 also includes a four-way valve 40. The four-way valve 40 is provided downstream of the first expansion section 30 and upstream of the compressor 10. The four-way valve 40 is configured to switch between a first state and a second state by switching the flow direction of the refrigerant expanded by the first expansion section 30 between a first flow direction and a second flow direction. The four-way valve 40 is an example of a "flow direction switching section" in the claims.

[0032] The four-way valve 40 is configured to switch the outflow destination of the refrigerant expanded by the first expansion section 30 by switching the flow path inside the four-way valve 40. The four-way valve 40 switches the refrigerant expanded by the first expansion section 30 to flow to the first evaporator 51 (evaporators 51a and 51b), thereby entering a first state in which the refrigerant expanded by the first expansion section 30 flows in a first flow direction. In addition, the four-way valve 40 switches the refrigerant expanded by the first expansion section 30 to flow to the second evaporator 52 (evaporators 52a and 52b), thereby entering a second state in which the refrigerant expanded by the first expansion section 30 flows in a second flow direction.

[0033] The cooling device 100 also includes a second expansion section 70. The second expansion section 70 is connected between the first evaporator 51 and the second evaporator 52, and is configured to expand the refrigerant flowing out of either the first evaporator 51 or the second evaporator 52. The second expansion section 70 includes expansion valves 70a and 70b. The expansion valve 70a is an example of a "first one-side expansion valve" in the claims, and the expansion valve 70b is an example of a "first other-side expansion valve" in the claims.

[0034] In the cooling device 100, the evaporator 51a, the expansion valve 70a, and the evaporator 52a are connected in series. Also, the evaporator 51b, the expansion valve 70b, and the evaporator 52b are connected in series. The expansion valves 70a and 70b are configured to expand the refrigerant flowing out of the evaporators 51a and 51b, respectively, in a first state described below. Also, the expansion valves 70a and 70b are configured to expand the refrigerant flowing out of the evaporators 52a and 52b, respectively, in a second state described below.

[0035] The first evaporator 51 (evaporators 51a and 51b) is configured so that in the second state, the refrigerant flowing out from the second evaporator 52 (evaporators 52a and 52b) flows into the first evaporator 51 (evaporators 51a and 51b) via the second expansion section 70 (expansion valves 70a and 70b). In the first state, the second evaporator 52 (evaporators 52a and 52b) is configured so that the refrigerant flowing out from the first evaporator 51 (evaporators 51a and 51b) flows into the second expansion section 70 (expansion valves 70a and 70b).

[0036] 1 to 3, the cooling device 100 includes a first fan 61 (fans 61a and 61b). The fans 61a and 61b are configured to send air to the evaporators 51a and 51b in the air flow path 91, respectively. Specifically, the fans 61a and 61b are configured to cool the air taken in from the intake port 94 during cooling of the first evaporator 51 through the evaporators 51a and 51b, respectively, and send the air to the air outlet 93.

[0037] Moreover, the fans 61a and 61b are configured to blow (supply) air to the evaporators 51a and 51b, respectively, when defrosting the first evaporator 51 (evaporators 51a and 51b) in the first state. Moreover, the fans 61a and 61b are configured to circulate air in the air flow path 92 including the evaporators 52a and 52b in the first state by making the air flow (airflow) in the opposite direction to that when cooling the first evaporator 51 (evaporators 51a and 51b) in the second state, thereby removing the frost from the first evaporator 51 (evaporators 51a and 51b). That is, in the first state, the direction in which the first fan 61 (fans 61a and 61b) blows (supplies) air is opposite to the direction in which the first fan 61 (fans 61a and 61b) blows (supplies) air in the second state. The first fan 61 (fans 61a and 61b) is disposed between the first evaporator 51 (evaporators 51a and 51b) and the air outlet 93.

[0038] The cooling device 100 also includes a second fan 62 (fans 62a and 62b) that blows air to the air flow passage 92 to circulate air when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. The fans 62a and 62b are driven when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. The fans 62a and 62b also reduce the amount of air blown when the second evaporator 52 (evaporators 52a and 52b) is defrosted in the second state compared to when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. For example, the fans 62a and 62b are stopped in the second state.

[0039] In addition, the cooling device 100 is provided with an accumulator 11 (a device for accumulating high-pressure refrigerant) downstream of the evaporators 51a, 51b, 52a, and 52b with respect to the flow of the refrigerant. In addition, the cooling device 100 is provided with a strainer 12 (a pipe for removing foreign matter from the refrigerant) downstream of the accumulator 11. In addition, a compressor 10 is provided downstream of the strainer 12.

[0040] The cooling device 100 is also provided with a bypass circuit that connects the inlet side of the refrigerant of the compressor 10 with the outlet side of the condenser 20. The bypass circuit is provided with a check valve 13, a strainer 14, and a capillary 15.

[0041] As shown in FIG. 1, the cooling device 100 includes a control unit 80 that controls each unit of the cooling device 100. Specifically, the control unit 80 controls the operation of the compressor 10. The control unit 80 also controls the operation of the blowers 61a, 61b, 62a, and 62b. The control unit 80 also controls the opening and closing of the solenoid valve 31. The control unit 80 also controls the opening and closing of the expansion valve 32. The control unit 80 also controls the opening and closing of the expansion valves 70a and 70b. In the first embodiment, the expansion valve 32 and the expansion valves 70a and 70b are electronic expansion valves configured to be electronically controllable in terms of opening degree.

[0042] Furthermore, the control unit 80 controls the switching of the flow direction of the refrigerant by the four-way valve 40. When the four-way valve 40 switches the flow direction of the refrigerant expanded by the first expansion unit 30 (expansion valve 32) to the first flow direction, the cooling device 100 enters a first state in which the first evaporator 51 (evaporators 51a and 51b) is defrosted and the second evaporator 52 (evaporators 52a and 52b) cools the air in the air flow path 92.

[0043] In addition, the cooling device 100 is configured to enter a second state in which, when the flow direction of the refrigerant expanded by the first expansion section 30 (expansion valve 32) is switched to the second flow direction by the four-way valve 40, the second evaporator 52 (evaporators 52a and 52b) is defrosted and the first evaporator 51 (evaporators 51a and 51b) cools the air in the air flow path 91.

[0044] The control unit 80 is configured to perform control to make the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) higher than that during cooling when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state, and control to remove frost adhering to the first evaporator 51 (evaporators 51a and 51b) by airflow caused by air blown by the first blower 61 (fans 61a and 61b). That is, the control unit 80 adjusts the opening degree of the expansion valve 32 of the first expansion unit 30 to adjust the flow rate of the refrigerant so that the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) is increased when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. For example, the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) is set to about -40°C during cooling (second state) and to about 0°C during defrosting (first state).

[0045] The control unit 80 is configured to perform control to make the temperature of the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) higher than the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state, and to perform control to reduce the amount of air sent by the second blower 62 compared to when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state. That is, the control unit 80 adjusts the opening degree of the expansion valve 32 of the first expansion unit 30 to adjust the flow rate of the refrigerant so that the temperature of the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) is higher when the second evaporator 52 (evaporators 52a and 52b) is defrosted in the second state. For example, the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) is set to about -40°C during cooling (second state) and to about 10°C during defrosting (first state).

[0046] 2, the cooling device 100 includes an air flow path 91 for air sent from the first blower 61 (blowers 61a and 61b) through the first evaporator 51 (evaporators 51a and 51b) to an air outlet 93. The cooling device 100 also includes an air flow path 92 through which air circulates when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state.

[0047] As shown in FIG. 2, the cooling device 100 includes a backflow suppression unit 95 that is disposed in the air flow path 92 downstream of the first evaporator 51 (evaporators 51a and 51b) during defrosting, and guides the air sent from the first evaporator 51 (evaporators 51a and 51b) to the air flow path 92 to suppress the backflow of air to the air inlet 94. Specifically, the backflow suppression unit 95 is formed to narrow the flow path of the air flow path 92. That is, the backflow suppression unit 95 is configured to narrow the flow path from the upstream side to the downstream side of the air flow path 92 during defrosting. As a result, during defrosting, the air blown out from the first evaporator 51 (evaporators 51a and 51b) side (X2 direction side) is guided to the second evaporator 52 (evaporators 52a and 52b) side (X1 direction side).

[0048] (First state operation) Next, the operation of the cooling device 100 in the first state will be described. In the first embodiment, the cooling device 100 is configured to, in the first state, flow the refrigerant expanded by the first expansion section 30 (expansion valve 32) in a first flow direction (see FIG. 4) that causes the refrigerant to flow in the order of the first evaporator 51 (evaporators 51a and 51b), the second expansion section 70 (expansion valves 70a and 70b), the second evaporator 52 (evaporators 52a and 52b), and the compressor 10, thereby defrosting the first evaporator 51 and cooling the air in the air flow path 92 by the second evaporator 52. In the first state and a second state described later, the solenoid valve 31 is in an open state.

[0049] In the first state, air having a flow velocity faster than that during cooling is sent to the heat transfer surface of the first evaporator 51 (evaporators 51a and 51b). Specifically, the fans 61a and 61b are driven so that the flow velocity of the air sent from the fans 61a and 61b during defrosting of the evaporators 51a and 51b is greater than the flow velocity of the air sent from the fans 61a and 61b during cooling.

[0050] First, the refrigerant is compressed by the compressor 10. As a result, the refrigerant becomes high temperature (about 60° C.) and high pressure. The compressor 10 is driven by a drive frequency of, for example, 60 Hz. Next, the refrigerant compressed by the compressor 10 is condensed (liquefied) by being cooled by the condenser 20. As a result, the refrigerant becomes medium temperature (about 30° C.) and high pressure.

[0051] Next, the liquefied refrigerant is expanded by the expansion valve 32. As a result, the pressure of the refrigerant becomes relatively low. In the first state, the opening degree of the expansion valve 32 of the first expansion section 30 is adjusted to adjust the flow rate of the refrigerant so that the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) is higher than that during cooling. However, the temperature of the heat transfer surface of the first evaporator 51 (evaporators 51a and 51b) during defrosting is 0°C or lower. For example, the refrigerant is set to a 0°C medium pressure in the expansion valve 32 and flows into the first evaporator 51 (evaporators 51a and 51b).

[0052] In the first evaporator 51 (evaporators 51a and 51b), the refrigerant is defrosted by the airflow of low-temperature air (about -25°C) and becomes a supercooled state of -10°C and medium pressure. By making the temperature of the heat transfer surface higher than the temperature of the heat transfer surface during cooling, the adhesion strength of the frost is reduced. As a result, in the first state of the cooling device 200, as shown in FIG. 5, the air blown from the first blower 61 (blowers 61a and 61b) can easily remove the frost adhering to the heat transfer surfaces of the evaporators 51a and 51b. That is, in the first state, wind pressure defrosting is performed on the first evaporator 51 (evaporators 51a and 51b).

[0053] The frost removed from the first evaporator 51 (evaporators 51a and 51b) and blown downstream is collected by the second evaporator 52 (evaporators 52a and 52b) as a collection section. At this time, the second evaporator 52 (evaporators 52a and 52b) is cooled by the refrigerant supplied from the first evaporator 51 (evaporators 51a and 51b) during defrosting through the second expansion section 70 (expansion valves 70a and 71b). In this case, the second evaporator 52 (evaporators 52a and 52b) is cooled to a lower temperature than the second evaporator 52 (evaporators 52a and 52b) during defrosting. For example, the refrigerant in a subcooled state of -10°C and medium pressure flowing out from the first evaporator 51 (evaporators 51a and 51b) is expanded by the second expansion section 70 (expansion valves 70a and 71b) to a low temperature (about -40°C) and low pressure. Then, in the second evaporator 52 (evaporators 52a and 52b), the low-temperature (about -40°C) low-pressure refrigerant that has flowed in is evaporated, the air is cooled, and moisture and frost are collected. As a result, the air temperature that has risen to about -20°C by defrosting (wind pressure defrosting) using the airflow of the first evaporator 51 (evaporators 51a and 51b) is recooled by the second evaporator 52 (evaporators 52a and 52b) to about -25°C. In addition, when defrosting the first evaporator 51 (evaporators 51a and 51b), the first blower 61 (blowers 61a and 61b) is driven. The low-temperature (about -40°C) low-pressure refrigerant evaporates in the second evaporator 52 (evaporators 52a and 52b), and the refrigerant that has become low-temperature (about -30°C) low-pressure flows into the compressor 10.

[0054] (Second state operation) Next, an operation of the cooling device 100 in the first state will be described. In the first embodiment, the cooling device 100 is configured to, in the second state, cause the refrigerant expanded by the first expansion section 30 (expansion valve 32) to flow in a second flow direction (see FIG. 6) through the second evaporator 52 (evaporators 52a and 52b), the second expansion section 70 (expansion valves 70a and 70b), the first evaporator 51 (evaporators 51a and 51b), and the compressor 10 in that order, thereby defrosting the second expansion section 70 and cooling the air in the air flow path 91 by the first evaporator 51.

[0055] First, as in the first state, the refrigerant is cooled and condensed (liquefied) by the condenser 20, and the refrigerant is expanded by the expansion valve 32 to become a medium-temperature (approximately 30°C) high-pressure refrigerant. This makes the pressure of the refrigerant relatively low. In the second state, the opening degree of the expansion valve 32 of the first expansion section 30 is adjusted to adjust the flow rate of the refrigerant so that the temperature of the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) is higher than the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) in the first state. For example, the refrigerant is brought to a medium pressure of 10°C in the expansion valve 32 and flows into the second evaporator 52 (evaporators 52a and 52b). At this time, the frost on the second evaporator 52 (evaporators 52a and 52b) melts as it is heated by the 10°C medium-pressure refrigerant, and the refrigerant flowing through the second evaporator 52 (evaporators 52a and 52b) is cooled by latent heat and becomes in a supercooled state of -10°C and medium-pressure.

[0056] At this time, the first evaporator 51 (evaporators 51a and 51b) is cooled by the refrigerant being supplied from the second evaporator 52 (evaporators 52a and 52b) undergoing defrosting via the second expansion section 70 (expansion valves 70a and 71b). In this case, the first evaporator 51 (evaporators 51a and 51b) is cooled to a temperature lower than that of the first evaporator 51 (evaporators 51a and 51b) undergoing defrosting. For example, the refrigerant in a subcooled state of -10°C and medium pressure flowing out of the second evaporator 52 (evaporators 52a and 52b) is expanded by the second expansion section 70 (expansion valves 70a and 71b) to a low temperature (about -40°C) and low pressure. Then, in the first evaporator 51 (evaporators 51a and 51b), the low-temperature (about -40°C) low-pressure refrigerant that has flowed in is evaporated, and the temperature of the air around the heat transfer surface of the first evaporator 51 (evaporators 51a and 51b) is lowered (cooled) by the heat of vaporization of the refrigerant. Also, the first blower 61 (fans 61a and 61b) blows air onto the heat transfer surface of the first evaporator 51 (evaporators 51a and 51b). As a result, the cooled air is blown into the cooling space (air flow path 91) to be cooled. Also, the heat of the air is transferred to the refrigerant, so that the refrigerant becomes low-temperature (about -30°C) and low-pressure. Also, the air of about -20°C sucked in from the suction port 94 is cooled to about -25°C by the first evaporator 51 (evaporators 51a and 51b) and blown out from the blowout port 93. Here, the air is cooled by the heat transfer surface, so the moisture in the air condenses (freezes) on the heat transfer surface. As a result, frost adheres (grows) on the heat transfer surface. The vaporized refrigerant is compressed again by the compressor 10.

[0057] Also, as shown in FIG. 7, in the second state, the first evaporator 51 is cooled, and the fans 61a and 61b are driven in the forward direction to draw in air from the intake port 94, pass through the fans 61a and 61b, and blow out the cooled air from the exhaust port 93.

[0058] In the second state, while the first evaporator 51 (evaporators 51a and 51b) is performing the cooling process, the second evaporator 52 (evaporators 52a and 52b) that was used as the collector in the first state is defrosted. The frost on the second evaporator 52 is heated by the 10°C medium-pressure refrigerant, melts, and is drained from the discharge part 96.

[0059] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0060] In the first embodiment, as described above, the first evaporator 51 and the second evaporator 52 evaporate the refrigerant expanded by the first expansion section 30, and the second expansion section 70 is connected between the first evaporator 51 and the second evaporator 52 and expands the refrigerant flowing out of either the first evaporator 51 or the second evaporator 52. Furthermore, the four-way valve 40 switches the flow direction of the refrigerant expanded by the first expansion section 30 (expansion valve 32) between the first flow direction and the second flow direction, so that the flow direction of the refrigerant flowing through the first evaporator 51, the second expansion section 70, and the second evaporator 52 can be switched between the first flow direction and the second flow direction. In the first state, the first evaporator 51 is defrosted, so that heat is taken from the refrigerant flowing through the first evaporator 51 (the enthalpy of the refrigerant decreases), and therefore the temperature (enthalpy) of the refrigerant flowing out of the first evaporator 51 decreases. Therefore, by switching the flow direction of the refrigerant flowing out of the first evaporator 51 and flowing into the second evaporator 52 as the first flow direction by the four-way valve 40, when the second evaporator 52 is cooled in the first state, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the first evaporator 51 flows into the second evaporator 52, which cools the air in the air flow path 92, via the second expansion section 70. As a result, the cooling capacity of the second evaporator 52 can be improved without increasing the flow rate of the refrigerant. In addition, in the second state, the defrosting of the second evaporator 52 removes heat from the refrigerant flowing through the second evaporator 52 (the enthalpy of the refrigerant decreases), so that the temperature (enthalpy) of the refrigerant flowing out of the second evaporator 52 decreases. Therefore, by switching the flow direction of the refrigerant flowing out of the second evaporator 52 and flowing into the first evaporator 51 as the second flow direction by the four-way valve 40, when the first evaporator 51 is cooled in the second state, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the second evaporator 52 flows into the first evaporator 51, which cools the air in the air flow path 91, via the second expansion section 70. As a result, the cooling capacity of the first evaporator 51 can be improved without increasing the flow rate of the refrigerant.Furthermore, since the high-temperature, high-pressure refrigerant supplied from the compressor 10 is expanded by the first expansion section 30 (expansion valve 32) and then supplied to the first evaporator 51 or the second evaporator 52, when defrosting each of the first evaporator 51 and the second evaporator 52, it is possible to suppress an increase in temperature around the first evaporator 51 and the second evaporator 52 compared to when the high-temperature, high-pressure refrigerant supplied from the compressor 10 is supplied to the first evaporator 51 or the second evaporator 52. As a result, it is possible to suppress an increase in the cooling load for maintaining the temperature inside the refrigerator when defrosting. In addition, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the first evaporator 51 (second evaporator 52) flows into the second evaporator 52 (first evaporator 51) through the second expansion section 70, and therefore the refrigerant whose temperature (enthalpy) has been reduced by defrosting the first evaporator 51 (second evaporator 52) evaporates by absorbing heat (the enthalpy increases) when the second evaporator 52 (first evaporator 51) is cooled. As a result, the refrigerant whose temperature (enthalpy) has been reduced by defrosting the first evaporator 51 (second evaporator 52) can be prevented from returning (liquid back) to the compressor 10 in a state in which the temperature (enthalpy) has been reduced (in a liquid state), and therefore the load on the compressor 10 caused by the liquid back can be suppressed.

[0061] In the first embodiment, as described above, the cooling device 100 is configured to, in the first state, cause the refrigerant expanded by the first expansion section 30 (expansion valve 32) to flow in a first flow direction in which the refrigerant flows through the first evaporator 51, the second expansion section 70, the second evaporator 52, and the compressor 10 in that order, thereby defrosting the first evaporator 51 and cooling the air in the air flow path 92 by the second evaporator 52. In the second state, the cooling device 100 is configured to, in the second state, cause the refrigerant expanded by the first expansion section 30 to flow in a second flow direction in which the refrigerant flows through the second evaporator 52, the second expansion section 70, the first evaporator 51, and the compressor 10 in that order, thereby defrosting the second evaporator 52 and cooling the air in the air flow path 91 by the first evaporator 51. As a result, in the first state, the refrigerant expanded by the first expansion section 30 is caused to flow in the first flow direction in which it flows in the first evaporator 51, the second expansion section 70, the second evaporator 52, and the compressor 10 in this order, thereby defrosting the first evaporator 51 and cooling the air in the air flow path 92 by the second evaporator 52, so that the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the first evaporator 51 flows through the second expansion section 70 into the second evaporator 52 which cools the air in the air flow path 92. As a result, the cooling capacity of the second evaporator 52 can be improved without increasing the flow rate of the refrigerant. In the second state, the refrigerant expanded by the first expansion section 30 is caused to flow in the second flow direction in which it flows through the second evaporator 52, the second expansion section 70, the first evaporator 51, and the compressor 10 in that order, thereby defrosting the second evaporator 52 and cooling the air in the air flow path 91 by the first evaporator 51. Therefore, the refrigerant whose temperature (enthalpy) has been reduced by the defrosting of the second evaporator 52 flows through the second expansion section 70 into the first evaporator 51 which cools the air in the air flow path 91. As a result, the cooling capacity of the first evaporator 51 can be improved without increasing the flow rate of the refrigerant. As a result, an increase in the cooling load for maintaining the temperature inside the refrigerator can be suppressed during defrosting.

[0062] In the first embodiment, as described above, the first expansion section 30 (expansion valve 32) is configured to adjust the pressure of the refrigerant to be discharged, thereby adjusting the temperature of the refrigerant flowing into the first evaporator 51 in the first state and the temperature of the refrigerant flowing into the second evaporator 52 in the second state. This allows the first expansion section 30 to adjust the temperature of the refrigerant flowing into the first evaporator 51 in the first state and the temperature of the refrigerant flowing into the second evaporator 52 in the second state, so that refrigerant at a temperature according to the respective locations of the first evaporator 51 and the second evaporator 52 and the defrosting method can be caused to flow. As a result, the first evaporator 51 and the second evaporator 52 can be defrosted efficiently.

[0063] In the first embodiment, as described above, the control unit 80 is configured to perform control to make the temperature of the refrigerant flowing into the first evaporator 51 higher than that during cooling when the first evaporator 51 is defrosted in the first state, and control to remove frost attached to the first evaporator 51 by airflow by airflow blown by the first blower 61 when the second evaporator 52 is defrosted in the second state, and control to make the temperature of the refrigerant flowing into the second evaporator 52 higher than the temperature of the refrigerant flowing into the first evaporator 51 when the first evaporator 51 is defrosted in the first state, and control to reduce the amount of air blown by the second blower 62 compared to when the first evaporator 51 is defrosted in the first state. As a result, the control of the control unit 80 in the first state can remove frost attached to the first evaporator 51 by airflow (wind pressure defrosting), thereby defrosting the first evaporator 51. Then, under the control of the control unit 80 in the second state, the frost adhering to the second evaporator 52 is melted by the heat of the refrigerant, thereby defrosting the second evaporator 52. As a result, when the second evaporator 52 is disposed downstream of the air blown by the first blower 61 in the first state, the second evaporator 52 can be used as a collector that collects frost and moisture that has sublimated and peeled off (removed) from the first evaporator 51 during defrosting of the first evaporator 51.

[0064] In the first embodiment, as described above, the evaporators 51a and 51b are connected in parallel between the four-way valve 40 and the second expansion section 70. The evaporators 52a and 52b are connected in parallel between the four-way valve 40 and the second expansion section 70. With this configuration, the first evaporators 51 (evaporators 51a and 51b) and the second evaporators 52 (evaporators 52a and 52b) are connected in parallel between the four-way valve 40 and the second expansion section 70. Therefore, unlike the case where the first evaporators 51 (evaporators 51a and 51b) and the second evaporators 52 (evaporators 52a and 52b) are connected in series, the refrigerant flows into the first evaporators 51 (evaporators 51a and 51b) and the second evaporators 52 (evaporators 52a and 52b) at the same flow rate and temperature. As a result, it is possible to easily control the refrigerant flow rate and refrigerant pressure during cooling in each of the plurality of first evaporators 51 (evaporators 51a and 51b) and the plurality of second evaporators 52 (evaporators 52a and 52b).

[0065] In the first embodiment, as described above, the evaporator 51a, the evaporator 52a, and the expansion valve 70a are connected in series, and the evaporator 51b, the evaporator 52b, and the expansion valve 70b are connected in series. With this configuration, the refrigerant flow path between the evaporator 51a and the evaporator 52a and the refrigerant flow path between the evaporator 51b and the evaporator 52b are provided independently, so that the expansion valves 70a and 70b can individually control the respective refrigerant flow paths. As a result, the flow rate of the refrigerant between the evaporator 51a (evaporator 52a) and the evaporator 51b (evaporator 52b) can be easily adjusted compared to the case where a common expansion valve is provided for the plurality of first evaporators 51 (evaporators 51a and 51b) and the plurality of second evaporators 52 (evaporators 52a and 52b).

[0066] In the first embodiment, as described above, the four-way valve 40 switches between the first state and the second state by switching the flow direction of the refrigerant expanded by the first expansion section 30 between the first flow direction and the second flow direction. This allows the flow direction of the refrigerant expanded by the first expansion section 30 (expansion valve 32) to be switched between the first flow direction and the second flow direction by switching the flow path inside the four-way valve 40. This makes it possible to suppress pressure loss compared to the case where the flow direction of the refrigerant is switched by a solenoid valve. As a result, it is possible to suppress an increase in the load of the compressor 10 due to a decrease in the flow rate of the refrigerant caused by pressure loss.

[0067] Second embodiment Next, the configuration of a cooling device 200 according to a second embodiment will be described with reference to Fig. 8 to Fig. 10. In the second embodiment, unlike the first embodiment in which the expansion valves 70a and 70b capable of bidirectionally flowing the refrigerant are used in the second expansion section 70, an example of a configuration (see Fig. 8) in which expansion valves 271a, 272a, 273a, and 274a capable of flowing the refrigerant in only one direction are used in the second expansion section 270 will be described. Note that the same reference numerals are used for the same configuration as in the first embodiment, and description thereof will be omitted.

[0068] Specifically, in the cooling device 200, the second expansion section 270 includes refrigerant flow paths 271, 272, 273, and 274, and expansion valves 271a, 272a, 273a, and 274a. The expansion valves 271a, 272a, 273a, and 274a are mechanical expansion valves such as temperature expansion valves. The second expansion section 270 also includes check valves 271b, 272b, 273b, and 274b.

[0069] The refrigerant flow path 271 is a flow path connected to the evaporator 51a and the evaporator 52a. The refrigerant flow path 273 is a flow path connected to the evaporator 51b and the evaporator 52b. The refrigerant flow paths 271 and 273 are examples of the "one refrigerant flow path" in the claims.

[0070] The expansion valves 271a and 273a are provided in the refrigerant flow paths 271 and 273, respectively, and are configured to expand the refrigerant flowing in a first flow direction (see FIG. 9) in the first state. The expansion valves 271a and 273a are examples of the "second one-way expansion valve" in the claims.

[0071] The check valve 271b is provided on the evaporator 52a side of the expansion valve 271a in the refrigerant flow path 271. The check valve 271b is configured to prevent the refrigerant from flowing in from the second flow direction (see FIG. 10). The check valve 273b is provided on the evaporator 52b side of the expansion valve 273a in the refrigerant flow path 273. The check valve 273b is configured to prevent the refrigerant from flowing in from the second flow direction (see FIG. 10).

[0072] Moreover, refrigerant flow path 272 is connected to evaporator 51a and evaporator 52a, and bypasses refrigerant flow path 271. And refrigerant flow path 274 is connected to evaporator 51b and evaporator 52b, and bypasses refrigerant flow path 273. Note that refrigerant flow paths 272 and 274 are examples of the "other refrigerant flow path" in the claims.

[0073] Moreover, the expansion valves 272a and 274a are provided in the refrigerant flow paths 272 and 274, respectively, and are configured to expand the refrigerant flowing in the second flow direction (see FIG. 10) in the second state. The expansion valves 272a and 274a are examples of the "second other expansion valve" in the claims.

[0074] The check valve 272b is provided on the evaporator 51a side of the expansion valve 272a in the refrigerant flow path 272. The check valve 272b is configured to prevent the refrigerant from flowing in from the first flow direction (see FIG. 9). The check valve 274b is provided on the evaporator 51b side of the expansion valve 274a in the refrigerant flow path 274. The check valve 274b is configured to prevent the refrigerant from flowing in from the first flow direction (see FIG. 9).

[0075] In the cooling device 200 according to the second embodiment, the evaporators 51a and 52a are provided with expansion valves 271a and 272a corresponding to the first and second flow directions, respectively. The evaporators 51b and 52b are provided with expansion valves 273a and 274a corresponding to the first (see FIG. 9) and second (see FIG. 10) flow directions, respectively.

[0076] The other configurations of the second embodiment are similar to those of the first embodiment.

[0077] (Effects of the second embodiment) In the second embodiment, similarly to the first embodiment, In addition, the total amount of circulating refrigerant can be prevented from increasing.

[0078] In the second embodiment, as described above, the second expansion section 270 includes an expansion valve 271a (273a) provided in the refrigerant flow passage 271 (273) and expanding the refrigerant flowing in the first flow direction in the first state, and an expansion valve 272a (274a) provided in the refrigerant flow passage 272 (274) and expanding the refrigerant flowing in the second flow direction in the second state. As a result, the expansion valve 271a (273a) and the expansion valve 272a (274a) are provided to correspond to the first flow direction and the second flow direction, respectively, so that the second expansion section 270 can be configured only with an expansion valve that can make the refrigerant flow in only one direction without using an expansion valve that can make the refrigerant flow in both directions. Also, the expansion valve 271a (273a) and the expansion valve 272a (274a) are provided to correspond to the first flow direction and the second flow direction, respectively. This allows the flow rate and temperature of the refrigerant to be adjusted by using a mechanical expansion valve, such as a temperature expansion valve, in the second expansion section 270, which detects the state of the refrigerant only in the corresponding flow direction (first flow direction and second flow direction).

[0079] Other effects of the second embodiment are similar to those of the first embodiment.

[0080] (Modification) The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications (variations) within the meaning and scope of the claims.

[0081] For example, in the above first and second embodiments, the cooling devices 100 and 200 are configured to open the top of the cooling space and cool the cooling space to a temperature of about -20°C, and are ice showcases for cooling frozen foods and ice creams, but the present invention is not limited to this. The present invention may also be applied to showcases that refrigerate foods and the like to temperatures around 0°C.

[0082] In the above first and second embodiments, an example of a configuration in which the expansion valve 32 is used in the first expansion section 30 and the expansion valves 70a and 70b are used in the second expansion section 70 is shown, but the present invention is not limited to this. In the present invention, a member other than an expansion valve, such as an ejector, may be used in the first expansion section or the second expansion section.

[0083] In the above first and second embodiments, the first expansion section 30 (expansion valve 32) is configured to adjust the pressure of the outflowing refrigerant to adjust the temperature of the refrigerant flowing into the first evaporator 51 (evaporators 51a and 51b) in the first state and the temperature of the refrigerant flowing into the second evaporator 52 (evaporators 52a and 52b) in the second state, but the present invention is not limited to this. In the present invention, the temperature of the refrigerant flowing into the first evaporator in the first state and the temperature of the refrigerant flowing into the second evaporator in the second state may be configured to be constant.

[0084] In the above first and second embodiments, the control unit 80 performs control to defrost the frost attached to the first evaporator 51 by wind pressure defrosting when the first evaporator 51 (evaporators 51a and 51b) is defrosted in the first state, and performs control to melt the frost attached to the second evaporator 52 by heating it with a 10°C medium-pressure refrigerant when the second evaporator 52 (evaporators 52a and 52b) is defrosted in the second state, but the present invention is not limited to this. In the present invention, control to defrost the attached frost by wind pressure defrosting when the first evaporator and the second evaporator are defrosted may be performed, or control to melt the attached frost by heating it with a 10°C medium-pressure refrigerant without using wind pressure defrosting when the first evaporator and the second evaporator are defrosted may be performed.

[0085] In the first and second embodiments, the cooling devices 100 and 200 are provided with the evaporators 51a and 51b as the first evaporator 51, and the evaporators 52a and 52b as the second evaporator 52, but the present invention is not limited to this. In the present invention, one each of the first evaporators and the second evaporators may be provided, or three or more each of the first evaporators and the second evaporators may be provided.

[0086] In the above first and second embodiments, the evaporator 51a (first one evaporator), the expansion valve 70a (first one expansion valve), and the evaporator 52a (second one evaporator) are connected in series, and the evaporator 51b (first other evaporator), the expansion valve 70b (first other expansion valve), and the evaporator 52b (second other evaporator) are connected in series, but the present invention is not limited to this. In the present invention, a common expansion valve may be provided for a plurality of first evaporators and a plurality of second evaporators.

[0087] In the second embodiment, mechanical expansion valves such as temperature expansion valves are used for the expansion valve 271a (second one side expansion valve), the expansion valve 272a (second other side expansion valve), the expansion valve 273a (second one side expansion valve), and the expansion valve 274a (second other side expansion valve), but the present invention is not limited to this. In the present invention, the second one side expansion valve and the second other side expansion valve may be expansion valves whose opening degree is adjusted by electronic control, such as electronic expansion valves.

[0088] In the above-mentioned first and second embodiments, the second evaporator 52 is provided on the suction port 94 side (X1 direction side) of the first evaporator 51, but the present invention is not limited to this. In the present invention, as in the cooling device 300 according to the first modification shown in FIG. 11, the first evaporator 351 (evaporators 351a and 351b) and the second evaporator 352 (evaporators 352a and 352b) may be configured to be adjacent to each other in the direction in which the air outlet 93 and the suction port 94 are adjacent to each other (X direction) and in the direction intersecting the up-down direction (Z direction) (Y direction). The evaporators 351a, 351b, 352a, and 352b are examples of the "first one evaporator", "first other evaporator", "second one evaporator", and "second other evaporator" in the claims, respectively.

[0089] In the above first and second embodiments, an example of a configuration in which the flow direction of the refrigerant is switched by the four-way valve 40 (flow direction switching unit) has been shown, but the present invention is not limited to this. In the present invention, the flow direction of the refrigerant may be switched by a flow direction switching unit other than a four-way valve. For example, as in a cooling device 400 according to a second modified example shown in FIG. 12, the flow direction of the refrigerant may be switched by a flow direction switching unit 440 composed of multiple solenoid valves (solenoid valves 441, 442, 443, and 444). [Explanation of symbols]

[0090] 10 Compressor 20 Condenser 30 First expansion section 40 Four-way valve (flow direction switching part) 51, 351 First evaporator 51a, 351a Evaporator (first one evaporator) 51b, 351b Evaporator (first other evaporator) 52, 352 Second evaporator 52a, 352a Evaporator (second one evaporator) 52b, 352b Evaporator (second other evaporator) 61 1st blower 61a Blower 61b Blower 62 2nd blower 62a Blower 62b Blower 70, 270 Second expansion section 70a Expansion valve (first one-way expansion valve) 70b Expansion valve (first other expansion valve) 90 Control section 91 Air passage 92 Air Flow Path 100, 200, 300, 400 chillers 271, 273 refrigerant flow path (one-way refrigerant flow path) 271a, 273a Expansion valve (second one-way expansion valve) 272, 274 refrigerant flow path (other refrigerant flow) 272a, 274a Expansion valve (second other expansion valve) 340 Flow direction change section

Claims

1. A cooling device for cooling a cooling space, comprising: A compressor that compresses a refrigerant; a condenser that condenses the refrigerant discharged from the compressor; a first expansion section that expands the refrigerant condensed by the condenser; a first evaporator and a second evaporator that are provided in an air flow path to which air for cooling the cooling space is sent and that evaporate the refrigerant expanded by the first expansion section provided upstream of the first evaporator; a flow direction switching unit that is provided downstream of the first expansion unit and upstream of the compressor and that switches a flow direction of the refrigerant expanded by the first expansion unit between a first flow direction and a second flow direction; a second expansion section connected between the first evaporator and the second evaporator and configured to expand the refrigerant flowing out of either the first evaporator or the second evaporator, The cooling device is configured so that, when the flow direction switching unit switches the flow direction of the refrigerant expanded and decompressed by the first expansion unit to the first flow direction, a first state is entered in which the first evaporator provided in the air flow path for cooling the cooling space is defrosted to remove frost that adheres to the first evaporator when the first evaporator is cooled, and the air in the air flow path is cooled by the second evaporator provided in the air flow path for cooling the cooling space, and when the flow direction switching unit switches the flow direction of the refrigerant expanded and decompressed by the first expansion unit to the second flow direction, a second state is entered in which the second evaporator is defrosted and the air in the air flow path is cooled by the first evaporator.

2. In the first state, the refrigerant expanded by the first expansion section is caused to flow in the first flow direction in which the refrigerant flows in the order of the first evaporator, the second expansion section, the second evaporator, and the compressor, thereby defrosting the first evaporator and cooling the air in the air flow path by the second evaporator.

2. The cooling device according to claim 1, wherein in the second state, the refrigerant expanded by the first expansion section is caused to flow in the second flow direction in which it flows in the order of the second evaporator, the second expansion section, the first evaporator, and the compressor, thereby defrosting the second evaporator and cooling the air in the air flow path by the first evaporator.

3. 3. The cooling device according to claim 1, wherein the first expansion section is configured to adjust the temperature of the refrigerant flowing into the first evaporator in the first state and the temperature of the refrigerant flowing into the second evaporator in the second state by adjusting the pressure of the refrigerant flowing out.

4. a blower for blowing air to the first evaporator in the air flow path; A control unit. The cooling device according to any one of claims 1 to 3, wherein the control unit is configured to perform control to make the temperature of the refrigerant flowing into the first evaporator higher than that during cooling when defrosting the first evaporator in the first state, and to remove frost adhering to the first evaporator by airflow caused by air blown by the blower.

5. The first evaporator and the second evaporator are each provided in plurality, The first evaporators are connected in parallel between the flow direction switching section and the second expansion section, The cooling device according to any one of claims 1 to 4, wherein the second evaporators are connected in parallel between the flow direction switching section and the second expansion section.

6. The plurality of first evaporators include a first first evaporator and a first second evaporator, The plurality of second evaporators include a second first evaporator and a second second second evaporator, the second expansion section includes a first one-way expansion valve and a first other-way expansion valve, the first one evaporator, the second one evaporator, and the first one expansion valve are connected in series, The cooling device according to claim 5 , wherein the first other evaporator, the second other evaporator and the first other expansion valve are connected in series.

7. The cooling device according to any one of claims 1 to 5, wherein the second expansion section includes: a first refrigerant flow path connected to the first evaporator and the second evaporator; a second first expansion valve provided in the first refrigerant flow path and expanding the refrigerant flowing in the first flow direction in the first state; a second other refrigerant flow path connected to the first evaporator and the second evaporator and bypassing the first refrigerant flow path; and a second other expansion valve provided in the other refrigerant flow path and expanding the refrigerant flowing in the second flow direction in the second state.

8. The cooling device according to any one of claims 1 to 7, wherein the flow direction switching unit includes a four-way valve that switches between the first state and the second state by switching the flow direction of the refrigerant expanded by the first expansion unit between the first flow direction and the second flow direction.

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