Cooling storage

Abstract

This device suppresses abnormal noises from check valves used in refrigeration circuits. [Solution] The cooling storage unit 10 includes a first cooler 22 for cooling a first storage chamber 12, a second cooler 23 for cooling a second storage chamber 13 to a lower temperature than the first storage chamber 12, a compressor 24 for compressing refrigerant from coolers 22 and 23, a check valve 70 to prevent refrigerant from the first cooler 22 from flowing into the second cooler 23, a valve 27 for switching the supply destination of refrigerant from the condenser 25 to at least one of the first cooler 22 or the second cooler 23, a first defrosting means 32, a second defrosting means 33, and a control unit 60. The control unit 60 operates the valve 27 so that refrigerant is supplied alternately to the first cooler 22 or the second cooler 23 when it operates the compressor 24 to perform a cooling operation after operating the first defrosting means 32 or the second defrosting means 33 to perform a defrosting operation.

Description

Technical Field

[0001] This technology relates to a cooling refrigerator.

Background Art

[0002] Conventionally, in a cooling refrigerator having a refrigerator compartment and a freezer compartment, when the volume of each compartment is small, it is known not to provide a refrigeration circuit for each cooler that cools each compartment, but to provide a common refrigeration circuit. An example of this is disclosed in Patent Document 1. The refrigeration cycle device described in Patent Document 1 has a flow path for supplying refrigerant to the refrigerator cooler, a flow path for supplying refrigerant to the freezer cooler, and a common flow path through which the refrigerant returns from the confluence point of the two flow paths to the compressor and the condenser. Further, the refrigeration cycle device includes a three-way valve for switching the supply destination of the refrigerant from the condenser and a check valve for preventing the refrigerant from flowing backward from the refrigerator cooler to the freezer cooler side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, as a check valve used in the above refrigeration circuit, a type having a valve body between the inlet side and the outlet side of the refrigerant is known. This type of check valve has a simple mechanism for preventing the backward flow of the refrigerant from the outlet side to the inlet side by the displacement of the valve body to close the gap. The check valve has the advantages of being able to reduce costs and simplify design and maintenance management.

[0005] ​However, in check valves with such a simple structure where the valve body is displaced, the valve body may become suspended depending on the pressure difference between the refrigerant on the inlet and outlet sides. A suspended valve body is susceptible to vibration and other factors, which can generate abnormal noises. When abnormal noises occur, users may find them unpleasant or mistakenly believe that a malfunction has occurred.

[0006] This technology was developed based on the circumstances described above, and its purpose is to suppress the generation of abnormal noises from check valves used in refrigeration circuits. [Means for solving the problem]

[0007] To solve the above problems, the cooling storage facility related to this technology is The first storage room and The second storage room, A first cooler for cooling the aforementioned first storage chamber, A second cooler that cools the second storage chamber to a lower temperature than the first storage chamber, A compressor for compressing the refrigerants from the first cooler and the second cooler, the compressor being located downstream in the direction of refrigerant flow from the point where the refrigerants from the first cooler and the refrigerants from the second cooler merge, A check valve is provided between the confluence point and the second cooler to prevent refrigerant from the first cooler from flowing into the second cooler, A condenser that liquefies the refrigerant gas compressed by the compressor, A valve that switches the supply destination of the refrigerant from the condenser to at least one of the first cooler or the second cooler, A first defrosting means for melting frost adhering to the first cooler, A second defrosting means for melting frost adhering to the second cooler, It comprises a control unit and, The check valve has a valve body that displaces according to the pressure difference between the refrigerant on the first cooler side and the refrigerant on the second cooler side, and the valve body displaces to open and close a gap. The control unit, The compressor is activated to perform a cooling operation. The compressor is stopped, and at least one of the first defrosting means or the second defrosting means is activated to perform a defrosting operation. When restarting the cooling operation by operating the compressor after the defrosting operation, the valve is operated so that the refrigerant is supplied alternately to the first cooler or the second cooler.

[0008] Also, The compressor has a variable-speed electric motor, and the speed at which it compresses and discharges the refrigerant is variable. The control unit, When operating the valve to supply refrigerant to the second cooler, the compressor may be operated at a predetermined speed or higher.

[0009] Also, The control unit, After the defrosting operation, the compressor is activated to restart the cooling operation, and the valve is operated so that the refrigerant is supplied to the second cooler. The compressor may initially be operated at the upper limit speed in the variable speed range, and then subsequently at a speed greater than or equal to the predetermined speed but less than the upper limit speed. [Effects of the Invention]

[0010] This technology can suppress the generation of abnormal noises from check valves used in refrigeration circuits. [Brief explanation of the drawing]

[0011] [Figure 1] Partially cut-out front view of the cooling storage unit according to this embodiment. [Figure 2] Cross-sectional view II in Figure 1 [Figure 3] Diagram showing a refrigeration circuit [Figure 4] Perspective view showing the components of a refrigeration circuit. [Figure 5] Block diagram showing the electrical configuration of the cooling storage unit. [Figure 6] Schematic diagram of a check valve [Figure 7] A schematic cross-sectional diagram showing the valve body of a check valve in contact with the valve seat. [Figure 8] Cross-sectional schematic view showing the state where the valve body of the check valve contacts the stopper [Figure 9] Cross-sectional schematic view obtained by cutting the main part of the check valve at the position of line II-II in FIG. 8 [Figure 10] Cross-sectional view showing the mounting posture of the check valve [Figure 11] Flowchart regarding control of cooling operation and defrosting operation [Figure 12] Timing chart regarding control of cooling operation and defrosting operation

Mode for Carrying Out the Invention

[0012] The cooling storage refrigerator 10 according to the present embodiment will be described with reference to FIGS. 1 to 12. In some of the drawings, directions are indicated using the signs F, B, L, R, U, D, which represent the front side (front side), the back side (rear side), the left side, the right side, the upper side, and the lower side when the cooling storage refrigerator 10 is viewed from the front, respectively.

[0013] As shown roughly in FIGS. 1 to 2, the cooling storage refrigerator 10 includes a storage refrigerator main body 11, a door 14, a machine room 16, a refrigeration circuit 20, and a control unit 60. The storage refrigerator main body 11 is a heat-insulated box body that opens forward, and a partition wall 11A that vertically partitions the internal space of the storage refrigerator main body 11 is provided at a substantially central portion in the vertical direction thereof. The internal space of the storage refrigerator main body 11 is divided into a refrigerating chamber 12 below the partition wall 11A and a freezing chamber 13 above it.

[0014] The refrigerating chamber 12 is an example of a first storage chamber, and stores stored items (such as foods) in a refrigerated state in a temperature range of about -1 °C to 3 °C, for example. The freezing chamber 13 is an example of a second storage chamber, and stores stored items in a frozen state in a temperature range of about -15 °C to -10 °C, for example. However, as long as the second storage chamber is cooled to a lower temperature than the first storage chamber, the cooling temperature zones of the first storage chamber and the second storage chamber are not limited, and both chambers may be refrigerating chambers or freezing chambers.

[0015] Door 14 is a swing-type insulated door that can open and close the front opening 11S of the storage unit body 11. There are two doors 14, one above the other, that can be opened and closed individually for the refrigerator compartment 12 and the freezer compartment 13.

[0016] A first cooling duct 45 is provided at the upper rear of the freezer compartment 13. Above the first cooling duct 45, a second cooler (freezer compartment cooler) 23 and a second circulation fan (freezer compartment internal fan) 53 are arranged to cool the freezer compartment 13. An intake port 45A is formed at the front of the first cooling duct 45 for drawing in air from inside the freezer compartment 13, and an outlet port 45B is provided at the rear for blowing cold air from the second cooler 23 into the freezer compartment 13.

[0017] A second cooling duct 46 is provided at the rear of the refrigerator compartment 12. Behind the second cooling duct 46, a first cooler (refrigerator cooler) 22 for cooling the refrigerator compartment 12 and a first circulation fan (refrigerator internal fan) 52 are installed. An intake port 46A is formed at the bottom of the second cooling duct 46 for drawing in air from inside the refrigerator compartment 12, and an outlet port 46B is provided at the top for blowing cold air from the first cooler 22 into the refrigerator compartment 12.

[0018] The machine room 16 is located above the main storage unit 11. The machine room 16 houses the machinery constituting the refrigeration circuit 20 (compressor 24 and condenser 25, etc.) and the control unit 60. The front of the machine room 16 is also provided with a display unit and operation unit 62, which consists of a screen for displaying various information and buttons for changing the cooling setting temperature, etc., by user operation. The machine room 16 can communicate with the inside of the main storage unit 11 through an opening provided in the upper wall 11B of the main storage unit 11, but this opening is insulated by fitting an insulating partition plate 15 from the machine room 16 side.

[0019] As shown in Figure 3, the refrigerated storage unit 10 includes a refrigeration circuit 20 in which two coolers 22 and 23, a compressor 24, a condenser 25, a dryer 26, a three-way valve 27 (an example of a valve), and a check valve 70 are connected by a refrigerant pipe 21. A cavilary tube (an example of an expansion valve) is provided between the three-way valve 27 and each of the coolers 22 and 23. As shown in Figure 4, the two coolers 22 and 23 are connected to a single refrigeration circuit 20 by a refrigerant pipe 21 that extends vertically.

[0020] Coolers 22 and 23 each cool the air passing through them by vaporizing the incoming refrigerant, thereby utilizing the heat of vaporization. Coolers 22 and 23 are, for example, fin-and-tube type heat exchangers or microchannel heat exchangers. The refrigerant gases from each cooler 22 and 23 mix at a confluence point 20X where the refrigerant pipes 21 are connected on their output side (downstream in the refrigerant flow direction). The mixture is then returned to the compressor 24 located downstream of the confluence point 20X. In this embodiment, an accumulator 28 is provided between the confluence point 20X and the compressor 24 to prevent liquid refrigerant that was not vaporized in the coolers 22 and 23 from returning to the compressor 24.

[0021] The compressor 24 is an inverter compressor equipped with a variable-speed electric motor. The compressor 24 uses the electric motor as a power source to draw in and compress refrigerant gas, and discharges high-temperature, high-pressure refrigerant gas. When the rotational speed of the electric motor increases, the amount of refrigerant gas drawn in and discharged by the compressor 24 increases, and the amount of refrigerant circulating in the refrigeration cycle increases, thereby increasing the cooling capacity of the refrigeration circuit 20. On the other hand, when the rotational speed of the electric motor decreases, the amount of refrigerant circulating in the refrigeration cycle decreases, so the cooling capacity of the refrigeration circuit 20 decreases. Also, the lower the rotational speed of the electric motor, the lower the power consumption of the electric motor and other components, resulting in energy savings. In this embodiment, the speed of the compressor 24 (rotational speed of the electric motor) is configured to be variable in three stages (specifically, low speed, medium speed, and high speed).

[0022] The condenser 25 cools and liquefies the refrigerant gas compressed by the compressor 24 using airflow from the condenser fan 29. The dryer 26 removes any moisture mixed in with the refrigerant liquid.

[0023] The three-way valve 27 switches the destination of the refrigerant liquid supplied from the condenser 25 after passing through the dryer 26. As shown in Figure 3, the refrigerant liquid supply from the three-way valve 27 is branched into two channels: the first branch channel 20A to the first cooler 22, or the second branch channel 20B to the second cooler 23. The three-way valve 27 is operated by the control unit 60 and is configured to supply refrigerant liquid in three states: supplying refrigerant liquid only to the first cooler 22 (refrigeration ON and freezing OFF, hereinafter referred to as the "first state"), supplying refrigerant liquid only to the second cooler 23 (refrigeration OFF and freezing ON, hereinafter referred to as the "second state"), or supplying refrigerant liquid to both the first cooler 22 and the second cooler 23 (refrigeration ON and freezing ON, hereinafter referred to as the "third state"). If the three-way valve 27 is not operated, refrigerant liquid is not supplied to either the first cooler 22 or the second cooler 23 (refrigeration OFF and freezing OFF).

[0024] In the refrigeration circuit 20, the flow path from the three-way valve 27 through the first cooler 22 to the confluence point 20X is designated as the first branch flow path 20A, and the flow path from the three-way valve 27 through the second cooler 23 and check valve 70 in order to the confluence point 20X is designated as the second branch flow path 20B. In addition, the flow path from the confluence point 20X through the compressor 24, condenser 25 and dryer 26 in order to the three-way valve 27 is designated as the common flow path 20C. The refrigeration circuit 20 is formed by a first circulation flow path (refrigeration cycle) consisting of the first branch flow path 20A and the common flow path 20C, and a second circulation flow path consisting of the second branch flow path 20B and the common flow path 20C.

[0025] As shown in Figure 5, the control unit 60 is electrically connected to various devices and controls them. The control unit 60 is, for example, a control board including a microcontroller, and may also be equipped with a memory unit and a timing unit. The control unit 60 performs the cooling operation by controlling the compressor 24, condenser fan 29, internal fans 52 and 53, and three-way valve 27. In addition, it performs a defrosting operation to melt the frost that has accumulated on the coolers 22 and 23 during the cooling operation. The cooling operation and defrosting operation will be described in detail later.

[0026] The cooling storage unit 10 also includes a first defrost heater 32, a second defrost heater 33, a first defrost sensor 42, and a second defrost sensor 43. The defrost heaters 32 and 33 melt the frost that accumulates on the coolers 22 and 23 during cooling operation. The defrost heaters 32 and 33 are positioned near each of the coolers 22 and 23 to efficiently melt the frost. Known heaters can be used as appropriate for the first defrost heaters 32 and 33.

[0027] The defrost sensors 42 and 43 detect the melting of frost on the coolers 22 and 23, respectively. Specifically, the defrost sensors 42 and 43 are temperature sensors (thermistors) that detect temperature changes in the coolers 22 and 23, respectively. The defrost sensors 42 and 43 are positioned near each of the coolers 22 and 23.

[0028] As shown in Figure 3, the check valve 70 is installed between the confluence point 20X and the second cooler 23. The check valve 70 prevents refrigerant from the first cooler 22 from flowing from the confluence point 20X to the second cooler 23. As shown in Figure 6, the check valve 70 is shaped like an elongated cylinder, with one opening of the cylinder being the inlet 70A and the other opening being the outlet 70B. The check valve 70 allows refrigerant from the inlet 70A (second cooler 23 side) to flow to the outlet 70B (confluence point 20X, first cooler 22 side), while restricting flow from the outlet 70B to the inlet 70A.

[0029] As shown in Figures 6 to 8, the check valve 70 comprises a housing 71, a valve seat 72, a valve body 73, and a stopper 74. The housing 71 is an elongated cylindrical (pipe-shaped) exterior member. The valve body 73 is a solid cylinder, with a tapered end 73A on the inlet 70A side. The valve body 73 displaces according to the pressure difference between the refrigerant on the inlet 70A side (second cooler 23 side) and the refrigerant on the outlet 70B side (first cooler 22 side). The valve seat 72 is a cylindrical member provided along the inner circumferential wall of the housing 71. The valve seat 72 has a projection 72A on the inlet 70A side that protrudes to reduce its inner diameter. The projection 72A of the valve seat 72 locks (contacts) the inlet 70A side end 73A of the valve body 73 when the valve body 73 is displaced towards the inlet 70A side. The stopper 74 is provided on the outlet 70B side of the valve body 73. When the valve body 73 is displaced toward the outlet 70B side, the stopper 74 locks (contacts) the end 73B of the valve body 73 toward the outlet 70B side.

[0030] As shown in Figure 10, the check valve 70 is positioned such that its longitudinal direction, which extends in an elongated shape from the inlet 70A to the outlet 70B, is in the vertical direction (from bottom to top). The longitudinal direction of the check valve 70 coincides with the displacement direction of the internal valve body 73.

[0031] When the compressor 24 is stopped and refrigerant is not circulating in the refrigeration circuit 20, there is almost no pressure difference between the refrigerant on the inlet 70A side and the refrigerant on the outlet 70B side of the check valve 70. As a result, the valve body 73 of the check valve 70 is displaced downward by its own gravity (self-weight), as shown in Figure 7, and the end 73A of the valve body 73 on the inlet 70A side comes into contact with the projection 72A of the valve seat 72. This closes the gap 70S (see Figure 8) between the valve body 73 and the projection 72A, preventing refrigerant from flowing from the outlet 70B side (first cooler 22 side) to the inlet 70A side (second cooler 23 side). Since the valve body 73 is in contact with the projection 72A of the valve seat 72 and is not floating, in this case, the problem of abnormal noise being generated in the check valve 70 due to vibration, etc., does not occur.

[0032] During normal cooling operation (cooling operation not immediately following defrosting), the freezer compartment 13 is at a lower temperature than the refrigerator compartment 12. Therefore, when the compressor 24 operates and the three-way valve 27 enters the first state (refrigeration ON and freezing OFF), forming the first circulation path, the refrigerant on the inlet 70A side (second cooler 23 side) of the check valve 70 is at a lower temperature and pressure than on the outlet 70B side (first cooler 22 side). The valve body 73 of the check valve 70 is displaced downward by this pressure difference and its own weight, and as shown in Figure 7, the end 73A on the inlet 70A side of the valve body 73 comes into contact with the projection 72A of the valve seat 72. Therefore, even in this case, the gap 70S between the valve body 73 and the projection 72A is closed, preventing refrigerant from flowing from the outlet 70B side to the inlet 70A side. Similarly, the problem of abnormal noise being generated in the check valve 70 due to vibration, etc., does not occur.

[0033] Furthermore, during normal cooling operation (cooling operation not immediately following defrosting), when the compressor 24 operates and the three-way valve 27 enters a second state (refrigeration OFF and freezing ON), and a second circulation path is formed, as shown in Figure 8, refrigerant flows through the inside of the check valve 70 from the inlet 70A to the outlet 70B. A force exceeding its own weight is applied upward to the valve body 73 (from the inlet 70A to the outlet 70B), and the end 73B of the valve body 73 on the outlet 70B side contacts the stopper 74. Since the valve body 73 is in contact with the stopper 74 and is not floating, in this case as well, the problem of abnormal noise being generated in the check valve 70 due to vibration, etc., does not occur.

[0034] By using a check valve 70 with such a simple configuration, costs can be reduced, and design and maintenance can be simplified.

[0035] Next, the operation control of the cooling storage unit 10 by the control unit 60 will be explained with reference to the flowchart in Figure 11 and the timing chart in Figure 12. As shown in Figure 11, the control unit 60 operates the compressor 24 at a low speed (step S10) and sets the three-way valve 27 to the first state (refrigeration ON and freezing OFF) (step S15) to perform cooling operation of the refrigerator compartment 12. As the refrigerator compartment 12 is cooled, the temperature detected by the first defrost sensor 42 decreases (cooling time T1 in Figure 12). Next, the compressor 24 is operated at a medium speed (step S17) and sets the three-way valve 27 to the second state (refrigeration OFF and freezing ON) (step S19) to perform cooling operation of the freezer compartment 13. As the freezer compartment 13 is cooled, the temperature detected by the second defrost sensor 43 decreases (cooling time T2 in Figure 12). When the cooling time T2 has elapsed, the control unit 60 stops the operation of the compressor 24 and the three-way valve 27 (steps S20, S25), and terminates the cooling operation.

[0036] After the cooling operation, the control unit 60 activates both the first defrost heater 32 and the second defrost heater 33 to start the defrosting operation (steps S30, S35). As the defrosting operation progresses, the temperature detected by the first defrost sensor 42 and the temperature detected by the second defrost sensor 43 increase (first defrosting time T3 in Figure 12). When the temperature detected by the first defrost sensor 42 exceeds a predetermined first threshold temperature Th1 (for example, 13°C) (YES in step S45), the control unit 60 determines that the frost on the first cooler 22 has melted, stops the first defrost heater 32 (step S50), and ends the defrosting operation of the first cooler 22.

[0037] Furthermore, when the temperature detected by the second defrost sensor 43 exceeds a predetermined second threshold temperature Th2 (for example, 22°C) (YES in step S55), the control unit 60 determines that the frost on the second cooler 23 has melted and stops the second defrost heater 33 (step S60), ending the defrosting operation of the second cooler 23. The second cooler 23 is colder than the first cooler 22, and the defrosting completion temperature detected by the second defrost sensor 43 is higher, so it takes longer to defrost the second cooler 23 than the first cooler 22. For this reason, after the first defrost heater 32 is stopped (step S50), a period of time (second defrosting time T4 in Figure 12) is provided during which the second defrost heater 33 continues to operate (NO in step S55). During the second defrosting time T4, the temperature of the first defrost sensor 42 decreases slightly, and the temperature of the second defrost sensor 43 continues to increase. Once the second defrosting time T4 has elapsed, the defrosting operations of both the first cooler 22 and the second cooler 23 will end, and the defrosting operation of the cooling storage unit 10 will be terminated. The first threshold temperature Th1 and the second threshold temperature Th2 can be arbitrarily changed according to the operating environment, etc.

[0038] After the defrosting operation, the control unit 60 restarts the cooling operation. In the restarted cooling operation, first, as shown in Figure 11, the compressor 24 is operated at low speed (step S65), and the three-way valve 27 is set to the first state (refrigeration ON and freezing OFF) (step S70), thereby performing the cooling operation of the refrigerator compartment 12. As the refrigerator compartment 12 is cooled, the temperature detected by the first defrost sensor 42 decreases (cooling time T5 in Figure 12). Next, the compressor 24 is operated at high speed (step S75), and the three-way valve 27 is set to the second state (refrigeration OFF and freezing ON) (step S80), thereby performing the cooling operation of the freezer compartment 13. As the freezer compartment 13 is cooled, the temperature detected by the second defrost sensor 43 decreases (cooling time T6 in Figure 12). Since the freezer compartment 13, which has been heated by the defrosting operation, is in a state where there is a large temperature difference from the set cooling temperature, the cooling time can be shortened by operating the compressor 24 at high speed in this way.

[0039] After cooling the freezer compartment 13 in this manner, the cooling of the refrigerator compartment 12 in steps S10 to S15 and the cooling of the freezer compartment 13 in steps S17 to S19 are repeated alternately (cooling times T7 and T8 in Figure 12).

[0040] Next, the effects of the operation control of the refrigerated storage unit 10 described above will be explained. One reason for the abnormal noise from the check valve 70 is that when restarting the cooling operation from the defrosting operation, if refrigerant flows into the first cooler 22 (refrigerator compartment cooler) and the second cooler 23 (freezer compartment cooler) simultaneously, the amount of refrigerant flowing into the check valve 70 is halved, and insufficient force is applied to displace (lift upward) the valve body 73 of the check valve 70 to the stopper 74 against its own weight, causing the valve body 73 to float. Furthermore, after the defrosting operation, the temperature of the refrigerator compartment 12 and the freezer compartment 13 is high, so the cooling operation time is generally long. If the valve body 73 floats and abnormal noise occurs, this can last for a long time, making it easy for users to feel uncomfortable or mistakenly believe that a malfunction has occurred.

[0041] Therefore, in this embodiment, the control unit 60 operates the three-way valve 27 so that refrigerant is alternately supplied to the first cooler 22 or the second cooler 23 when restarting the cooling operation from the defrosting operation. More specifically, as shown in Figures 11 and 12, the three-way valve 27 is operated by alternately switching between a first state (refrigeration ON and freezing OFF) or a second state (refrigeration OFF and freezing ON). The three-way valve 27 is never operated by switching to a third state (refrigeration ON and freezing ON). In this way, the flow rate of refrigerant flowing into the check valve 70 is not halved, and the valve body 73 does not become suspended. As a result, the situation in which the suspended valve body 73 is subjected to vibration and generates abnormal noise can be effectively suppressed.

[0042] Furthermore, when the control unit 60 restarts the cooling operation from the defrosting operation, if the three-way valve 27 is operated in the second state (refrigeration OFF and freezing ON), the motor of the compressor 24 is operated at a predetermined speed (medium speed in this embodiment) or higher (medium speed in step S17 of Figure 11, and high speed in step S75).

[0043] When the three-way valve 27 is operated in the second state (refrigeration OFF and freezing ON), refrigerant is supplied to the second cooler 23. However, the refrigerant flowing into the check valve 70 from the second cooler 23 flows in in a vaporized state, which tends to reduce the force required to lift the valve body 73 of the check valve 70 up to the stopper 74. Therefore, by operating the compressor 24 at a medium speed or higher, the flow rate of refrigerant flowing into the check valve 70 can be increased. As a result, the valve body 73 does not become suspended, and the occurrence of abnormal noise due to vibration, etc., can be more reliably suppressed.

[0044] Furthermore, when the control unit 60 restarts the cooling operation from the defrosting operation, if the three-way valve 27 is operated in the second state (refrigeration OFF and freezing ON), it first operates at the upper limit speed in the variable speed range (in this embodiment, step S75 in Figure 11 and "high speed" in the cooling time T6 in Figure 12), and then operates at a predetermined speed or higher but less than the upper limit speed (in this embodiment, step S17 in Figure 11 and "medium speed" in the cooling time T8 in Figure 12).

[0045] In this way, immediately after restarting the cooling operation, the compressor 24 is rotated at its maximum speed to increase the amount of refrigerant supplied to the second cooler 23, thereby rapidly cooling the second cooling chamber 23, which has risen in temperature due to the defrosting operation. Furthermore, thereafter, the compressor 24 can be operated at a speed above the predetermined speed to suppress abnormal noise from the check valve 70, while power consumption can be reduced by operating it below the maximum speed.

[0046] <Other Embodiments> This technology is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of this technology.

[0047] (1) The defrosting operation is not limited to the timing shown in the flowchart in Figure 11; it may also be performed automatically after a predetermined cooling operation period or manually forcibly.

[0048] (2) The first defrosting means and the second defrosting means are not limited to the first defrosting heater 32 and the second defrosting heater 33, respectively. For example, when a so-called off-cycle defrosting method is adopted, the first internal fan 52 and the second internal fan 53 may also be used.

[0049] (3) This technology can be applied to equipment other than the refrigerated storage unit 10, as long as it is equipped with the refrigeration circuit 20 described above. [Explanation of symbols]

[0050] 10: Cooling storage unit, 12: Refrigerated room (first storage room), 13: Freezer room (second storage room), 20X: Confluence point, 22: First cooler, 23: Second cooler, 24: Compressor, 27: Three-way valve, 60: Control unit, 70: Check valve, 70S: Gap, 73: Valve body

Claims

1. The first storage room and The second storage room, A first cooler for cooling the first storage chamber, A second cooler that cools the second storage chamber to a lower temperature than the first storage chamber, A compressor for compressing the refrigerants from the first cooler and the second cooler, the compressor being located downstream in the direction of refrigerant flow from the point where the refrigerants from the first cooler and the refrigerants from the second cooler merge, A check valve is provided between the confluence point and the second cooler to prevent refrigerant from the first cooler from flowing into the second cooler, A condenser that liquefies the refrigerant gas compressed by the compressor, A valve that switches the supply destination of the refrigerant from the condenser to at least one of the first cooler or the second cooler, A first defrosting means for melting frost adhering to the first cooler, A second defrosting means for melting frost adhering to the second cooler, It comprises a control unit and, The check valve has a valve body that displaces according to the pressure difference between the refrigerant on the first cooler side and the refrigerant on the second cooler side, and the valve body displaces to open and close a gap. The control unit, The compressor is activated to perform a cooling operation. The compressor is stopped, and at least one of the first defrosting means or the second defrosting means is activated to perform a defrosting operation. A cooling storage unit that operates the valves so that when the compressor is operated to restart the cooling operation after the defrosting operation, the refrigerant is supplied alternately to the first cooler or the second cooler.

2. The compressor has a variable-speed electric motor, and the speed at which it compresses and discharges the refrigerant is variable. The control unit, The cooling storage unit according to claim 1, wherein when the valve is operated to supply refrigerant to the second cooler, the compressor is operated at a predetermined speed or higher.

3. The control unit, After the defrosting operation, the compressor is activated to restart the cooling operation, and the valve is operated so that the refrigerant is supplied to the second cooler. The cooling storage unit according to claim 2, wherein the compressor is first operated at the upper limit speed in the variable speed range, and thereafter operated at a predetermined speed or higher and below the upper limit speed.

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