Cooling device

Abstract

To more reliably suppress a rise in temperature inside a storage facility during defrosting. [Solution] A cooling device having multiple heat exchangers 10 inside a storage 31 is adopted, which is equipped with a first refrigerant passage 51 for supplying refrigerant connected to one heat exchanger A among the multiple heat exchangers 10, a second refrigerant passage 52 for supplying refrigerant connected to another heat exchanger B that has a relatively smaller amount of frost formation than the first heat exchanger A, and a control unit 40 that performs defrost control to cut off the supply of refrigerant to at least one of the first refrigerant passage 51 and the second refrigerant passage 52 for the purpose of defrosting.

Description

[Technical Field]

[0001] The present invention relates to a cooling device that suppresses temperature changes inside a storage facility during defrosting. [Background technology]

[0002] Natural convection refrigerators have traditionally been used primarily as commercial refrigerators. A natural convection refrigerator has a cooling heat exchanger (fin coil) placed inside the storage compartment, and cools the storage compartment by natural convection of the cold air cooled by the heat exchanger. This type of natural convection refrigerator, also known as a direct-cooling refrigerator, has the advantage that cold air is not blown directly onto the refrigerated items, preventing the items from drying out. Natural convection refrigerators also emit less cold air when the storage compartment door is opened than fan-type refrigerators, resulting in smaller temperature changes inside the storage compartment, and are therefore also used in commercial refrigerators.

[0003] For example, the natural convection refrigerator of Patent Document 1 has a storage compartment provided with multiple shelves for placing stored items, and multiple heat exchangers for cooling are provided in the upper part of the storage compartment. The lower part of the heat exchangers is covered with a drain pan for defrosting. A compressor (freezer) is connected to the heat exchangers. The freezer compresses and supplies refrigerant to the heat exchanger, and cold air is generated by heat exchange of the refrigerant in the heat exchanger. The cold air naturally convects within the storage compartment, thereby cooling the interior of the storage compartment. At this time, the temperature within the storage compartment is maintained at a constant temperature by a control unit equipped with a temperature controller or the like.

[0004] In natural convection refrigerators such as those described above, frost may accumulate on the heat exchanger. When frost accumulates on the heat exchanger, it may impede the convection of cool air, resulting in a decrease in cooling capacity. For this reason, efforts are generally made to restore cooling capacity by using off-cycle defrosting, which temporarily stops the supply of refrigerant, or heater defrosting, which uses the heat of a heater to defrost the refrigerator. Off-cycle defrosting is a method of melting frost by circulating air inside the refrigerator while stopping the compressor for a certain period of time, while heater defrosting is a method of melting frost by applying heat to the heater through electrical current. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication number 7-44935 Summary of the Invention [Problem to be solved by the invention]

[0006] However, defrosting temporarily raises the temperature inside the storage facility, which may damage the refrigerated items. For this reason, it is preferable to defrost as efficiently as possible in the shortest possible time.

[0007] In this regard, the natural convection refrigerator of Patent Document 1 has four heat exchangers, each of which has a rectangular parallelepiped outer shape, arranged in parallel along one direction, and there is a tendency for frost to form on the outer surfaces of the heat exchangers at both ends of the parallelepiped arrangement (the sides on which there are no adjacent heat exchangers).

[0008] Here, the four heat exchangers are arranged in a parallel direction, with two heat exchangers located on one side cooled by one cooling circuit and two heat exchangers located on the other side cooled by a different cooling circuit. Because one cooling circuit and the other cooling circuit each contain heat exchangers with relatively high frost formation and others with relatively low frost formation, the defrosting time for each circuit is set to the time until the frost on the heat exchanger with the highest frost formation is removed. This creates a problem: the heat exchanger with no frost formation cannot perform its cooling function until the frost on the heat exchanger with the highest frost formation is removed. This lengthens the time required for defrosting, leaving room for improvement in suppressing temperature increases within the storage facility.

[0009] Furthermore, when defrosting is performed, water droplets tend to fall from the heat exchanger into the storage facility. This is undesirable as it may cause deterioration of the stored goods. In particular, when the pipes extending from the heat exchangers at both ends of a parallel arrangement of heat exchangers extend beyond the outer edge of the drain pan, the water droplets are likely to not be retained in the drain pan. As mentioned above, the heat exchangers at both ends are prone to frost formation, so it is desirable to more reliably prevent water droplets from falling into the storage facility.

[0010] Therefore, the first objective of this invention is to more reliably suppress the rise in temperature inside the storage facility during defrosting, and the second objective is to suppress the falling of water droplets into the storage facility during defrosting. [Means for solving the problem]

[0011] In order to solve the first problem, the present invention employs a cooling device having a plurality of heat exchangers in a storage compartment, the cooling device including: a first refrigerant passage for supplying refrigerant connected to one of the plurality of heat exchangers; a second refrigerant passage for supplying refrigerant connected to another heat exchanger having a relatively smaller amount of frost formation than the first heat exchanger; and a control unit that performs defrost control to cut off the supply of refrigerant to at least one of the first refrigerant passage and the second refrigerant passage for the purpose of defrosting (Configuration 1).

[0012] In configuration 1, the multiple heat exchangers each have a longitudinal shape and are arranged in parallel along one direction so that their longitudinal directions are parallel to each other, and the one heat exchanger is a first heat exchanger located at one end of the multiple heat exchangers along one direction and a second heat exchanger located at the other end, and the other heat exchanger is a heat exchanger other than the first heat exchanger and the second heat exchanger (configuration 2).

[0013] In order to solve the second problem, the present invention can adopt a configuration in which, in configuration 1 or 2, the outlet portion of the refrigerant piping in the first heat exchanger is located inward in the parallel direction from the center line of the first heat exchanger in one direction of its width, and the outlet portion of the refrigerant piping in the second heat exchanger is located inward in the parallel direction from the center line of the second heat exchanger in one direction of its width, and the outlet portions of the first heat exchanger and the second heat exchanger are covered below with drain pans (configuration 3).

[0014] Furthermore, in order to solve the second problem, the present invention provides a cooling device having a plurality of heat exchangers in a storage facility, wherein the heat exchangers are each longitudinally shaped and arranged in parallel along one direction with their longitudinal directions parallel to one another, and among the plurality of heat exchangers, an outlet portion of a refrigerant pipe in a first heat exchanger located at one end along one direction is located inward in the parallel direction from a center line of the first heat exchanger relative to its width in one direction, and an outlet portion of a refrigerant pipe in a second heat exchanger located at the other end along the one direction is located inward in the parallel direction from a center line of the second heat exchanger relative to its width in one direction, and the outlet portions of the first heat exchanger and the second heat exchanger can be configured such that their lower portions are covered with drain pans (configuration 4).

[0015] In any one of configurations 1 to 4, the control unit can employ a configuration that performs either an implementation duration control that sets the time during which the refrigerant supply to the first refrigerant passage is cut off per one defrost control longer than the time during which the refrigerant supply to the second refrigerant passage is cut off per one defrost control, or an implementation interval control that sets the implementation interval of the defrost control for the first refrigerant passage shorter than the implementation interval of the defrost control for the second refrigerant passage (configuration 5).

[0016] In any one of configurations 1 to 5, a configuration can be adopted in which a first main heater is provided adjacent to one of the heat exchangers and a second main heater is provided adjacent to the other heat exchanger, and the control unit selectively controls to activate at least one of the first main heater and the second main heater during the defrost control (configuration 6).

[0017] In any one of configurations 1 to 6, the lower sides of the one heat exchanger and the other heat exchanger are covered with a drain pan, and a first drain pan heater is provided in the drain pan directly below the one heat exchanger, and a second drain pan heater is provided in the drain pan directly below the other heat exchanger, and a configuration can be adopted in which the control unit selectively controls to operate at least one of the first drain pan heater and the second drain pan heater during the defrost control (configuration 7). [Effects of the Invention]

[0018] According to this invention, it is possible to more reliably suppress the rise in temperature inside the storage compartment during defrosting, and also to suppress the falling of water droplets into the storage compartment due to defrosting. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a cooling device according to an embodiment of the present invention; [Figure 2] Perspective view of Figure 1 [Figure 3] FIG. 2 is a schematic diagram showing a cooling circuit of the cooling device according to the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 , a cooling device 30 of this embodiment is a commercial refrigerator having a storage compartment 31 with a door 32 that can be opened and closed, and multiple shelves for storing stored goods. Multiple heat exchangers 10 for cooling are provided in the upper part of the storage compartment 31. The lower part of the heat exchangers 10 is covered with a drain pan 1 to prevent water droplets from falling. Reference numeral 2 in the figure denotes a through-hole through which cool air passes downward. The heat exchangers 10 constitute part of a cooling circuit 50. The cooling circuit 50 includes a compressor (freezer / compressor) 41. The compressor 41 compresses and supplies a refrigerant toward the heat exchanger 10. The refrigerant exchanges heat with the heat exchanger 10, removing heat from the surrounding air to generate cool air within the storage compartment 31. Natural convection of the cool air within the storage compartment 31 cools the interior of the storage compartment 31, and the stored goods are also kept cool.

[0021] Heat exchanger 10, also known as a cooling coil, is a heat exchange device that cools the air outside the tubes using a refrigerant flowing through thin tubes arranged inside. The refrigerant piping provided in heat exchanger 10 is arranged in a coil shape, and fins F (see Figure 2) that come into contact with the air are also provided around the refrigerant piping, so the device is generally also called a cooling coil or fin coil.

[0022] 1, each heat exchanger 10 has a longitudinal shape (the outer shape connecting the outermost edges of the device is a rectangular parallelepiped) that is separated from one another, and a plurality of heat exchangers 10 are provided in parallel along one direction so that their longitudinal directions are parallel to one another within the storage 31. In this embodiment, five heat exchangers 10 are provided.

[0023] As shown in FIG. 3, the cooling circuit 50 equipped with the compressor 41 has a first refrigerant passage 51 for supplying refrigerant connected to one heat exchanger A among the plurality of heat exchangers 10, and a second refrigerant passage 52 for supplying refrigerant connected to another heat exchanger B that has a relatively smaller amount of frost formation than the first heat exchanger A, which are arranged in parallel.

[0024] In this embodiment, one heat exchanger A corresponds to the first heat exchanger 11 located at one end along one direction and the second heat exchanger 12 located at the other end along the other direction among the plurality of heat exchangers 10. Another heat exchanger B corresponds to the other heat exchangers excluding the first heat exchanger 11 and the second heat exchanger 12, i.e., the third heat exchanger 13, the fourth heat exchanger 14, and the fifth heat exchanger 15. The third heat exchanger 13, the fourth heat exchanger 14, and the fifth heat exchanger 15 are sandwiched between the first heat exchanger 11 and the second heat exchanger 12 located at both ends along one direction.

[0025] 3, the refrigerant passage constituting the cooling circuit 50 branches into a first refrigerant passage 51 and a second refrigerant passage 52 at the switching device 44. The first refrigerant passage 51 branches into a refrigerant pipe (first branch passage) 51a leading to the first heat exchanger 11 and a refrigerant pipe (second branch passage) 52a leading to the second heat exchanger 12. The second refrigerant passage 52 branches into a refrigerant pipe (third branch passage) 52a leading to the third heat exchanger 13, a refrigerant pipe (fourth branch passage) 52b leading to the fourth heat exchanger 14, and a refrigerant pipe (fifth branch passage) 52c leading to the fifth heat exchanger 15. The first branch passage 51a, the second branch passage 51b, the third branch passage 52a, the fourth branch passage 52b, and the fifth branch passage 52c each pass through their respective heat exchangers 10, then merge into a single downstream refrigerant passage 53 and return to the compressor 41.

[0026] In addition to the heat exchanger 10 and the compressor 41, the cooling circuit 50 is provided with a condenser 42, an expansion valve 43, and a switching device 44.

[0027] The refrigerant absorbs heat from within the storage tank 31 by the heat exchanger 10. Here, the liquid refrigerant evaporates and vaporizes in the process of absorbing heat from within the storage tank 31, so the heat exchanger 10 functions as an evaporator. Since the heat exchanger 10 is equipped with fins F, it can efficiently absorb heat from the air and the like within the storage tank 31, thereby cooling the air and stored goods within the storage tank 31.

[0028] The refrigerant that has absorbed heat from inside the storage tank 31 is compressed to high pressure by the compressor 41. As a result, the refrigerant becomes a gas in a high-temperature, high-pressure state. The refrigerant sent out from the compressor 41 enters the condenser 42. In the condenser 42, the refrigerant is cooled by outside air and its temperature drops. The refrigerant liquefies in the condenser 42 and then reaches the expansion valve 43. The refrigerant expands suddenly as it passes through the expansion valve 43, and its pressure drops. As the pressure drops, the temperature of the refrigerant drops rapidly, and the low-temperature refrigerant is supplied to the heat exchanger 10.

[0029] The control unit 40 can adjust the opening of the valve device provided in the switching device 44 so that the high-temperature, high-pressure refrigerant from the compressor 41 does not flow into the condenser 42 more than necessary. The storage tank 31 is also provided with a thermostat (not shown) as a means for adjusting the temperature inside the storage tank. The control unit 40 controls the amount of refrigerant supplied so that the temperature inside the storage tank 31 falls within a predetermined range through the operation of the thermostat. Note that means other than a thermostat may be used as the means for adjusting the temperature inside the storage tank.

[0030] The refrigerant delivered by the compressor 41 is supplied to a predetermined heat exchanger 10 selected by the switching device 44, or to all of the heat exchangers 10.

[0031] In the embodiment, the switching device 44 can selectively switch between a first state in which the refrigerant is supplied only to one heat exchanger A (the heat exchanger 10 on the first refrigerant passage 51 side), a second state in which the refrigerant is supplied only to another heat exchanger B (the heat exchanger 10 on the second refrigerant passage 52 side), and a third state in which the refrigerant is supplied to both the one heat exchanger A and the other heat exchanger B (the heat exchangers 10 on the first refrigerant passage 51 side and the second refrigerant passage 52 side). The control for switching the refrigerant passage (hereinafter referred to as passage switching control) is automatically performed by the control unit 40 depending on the environment in the storage tank 31 or based on preset conditions, but it can also be performed manually.

[0032] The switching device 44 may be, for example, a valve device that can switch the opening direction of the cooling circuit 50. Here, one valve device may be used to switch the flow path between the first state (first refrigerant passage 51), the second state (second refrigerant passage 52), and the third state (first refrigerant passage 51 and second refrigerant passage 52), or multiple valve devices may be used to switch the flow paths in a similar manner.

[0033] Incidentally, frost often accumulates on the heat exchanger 10. For this reason, it is desirable to perform defrosting control to remove the accumulated frost at regular intervals. Typical defrosting controls include hot gas control, in which hot gas is fed into the heat exchanger 10 for a fixed period of time, heating control, in which the heat exchanger 10 is heated by a heater disposed adjacent to the heat exchanger 10, and off-time control, in which the supply of refrigerant to the heat exchanger 10 is stopped for a fixed period of time to melt the frost.

[0034] The cooling device 30 of the present invention employs off-time control as one means of defrost control. In off-time control, the flow path is set to the first state (first refrigerant passage 51) or the second state (second refrigerant passage 52) by the flow path switching control described above, i.e., defrosting is performed by cutting off the supply of refrigerant to either the first refrigerant passage 51 or the second refrigerant passage 52. When defrosting is not performed, the flow path is set to the normal cooling state, i.e., the third state (first refrigerant passage 51 and second refrigerant passage 52). When defrosting all of the heat exchangers 10 simultaneously, the compressor 41 is stopped to stop the supply of refrigerant to all of the heat exchangers 10.

[0035] Here, as described above, compared with one heat exchanger A (the first heat exchanger 11 and the second heat exchanger 12) located at both ends, another heat exchanger B (the third heat exchanger 13, the fourth heat exchanger 14, and the fifth heat exchanger 15) located inside thereof tends to have a relatively small amount of frost formation. Therefore, in this invention, since the control unit 40 can selectively set the first state (the first refrigerant passage 51) or the second state (the second refrigerant passage 52), the heat exchanger 10 that stops the supply of refrigerant can be selectively set. As a result, a situation where the heat exchanger 10 that has no (or little) frost formation and can continue cooling without problems has its cooling function stopped until the defrosting of the heat exchanger 10 with a large amount of frost formation is completed can be avoided, and efficient cooling inside the storage 31 is possible.

[0036] As this defrost control by off-time control, the control unit 40 is set to perform a continuous operation time control (T1>T2) in which the refrigerant supply interruption time T1 for the first refrigerant passage 51 per defrost control is set longer than the refrigerant supply interruption time T2 for the second refrigerant passage 52 per defrost control. For example, in a setting where the supply of refrigerant is continuously continued over a certain continuous operation time F0 (for example, 12 hours or 24 hours, etc.) and then the off-time control is started, a method of setting a difference in the stop time of refrigerant supply, such as setting the refrigerant supply interruption time T1 to 60 minutes and the refrigerant supply interruption time T2 to 10 minutes, can be cited. Such control can be implemented by a timer provided in the control unit 40.

[0037] Also, as another method, an implementation interval control (T11<T12) in which the implementation interval T11 of the defrost control for the first refrigerant passage 51 is set shorter than the implementation interval T12 of the defrost control for the second refrigerant passage 52 may be set. For example, in a setting where the supply of refrigerant is continuously interrupted over a certain specified supply interruption time T0 (for example, 30 minutes), a method of setting a difference in the implementation interval (refrigerant supply continuous time) of the defrost control, such as setting the implementation interval T11 to 30 minutes until the next defrost control is started after the supply of refrigerant is restarted in the first refrigerant passage 51 and setting the same implementation interval T2 for the second refrigerant passage 52 to 180 minutes, can be cited. Such control can also be implemented by a timer provided in the control unit 40.

[0038] Furthermore, as another method, an implementation integrated time control (D1>D2) may be set in which an integrated supply cutoff time D1, which is an integrated value of the time for which the refrigerant supply is cut off to the first refrigerant passage 51, is set to be longer than an integrated supply cutoff time D2, which is an integrated value of the time for which the refrigerant supply is cut off to the second refrigerant passage 52, by totaling a certain calculation period D0. For example, a method may be used in which a difference is set in the integrated time (total time) for stopping the refrigerant, such that the integrated supply cutoff time D1 to the first refrigerant passage 51 and the integrated supply cutoff time D2 to the second refrigerant passage 52, which are integrated over a certain calculation period D0 (e.g., one week = 24 hours × 7 days = 168 hours), are set to 30 hours and 5 hours, respectively. Such control can be performed by a timer, a counter, or the like provided in the control unit 40.

[0039] Furthermore, as another method, flow path switching control is performed based on information from frost state detection means (not shown) provided in the storage tank 31, and when a predetermined amount of frost is detected, the refrigerant flow path is selectively set to a first state (first refrigerant passage 51) or a second state (second refrigerant passage 52) depending on the frost state. As the frost state detection means, for example, a method is available in which a pair of electrodes is disposed in the heat exchanger 10 and the presence or absence of frost or the amount of frost is detected based on a change in the resistance value between the pair of electrodes due to frost formation. Another configuration of the frost state detection means is, for example, a method in which an image of the periphery of the heat exchanger 10 is acquired by a camera provided in the storage tank 31 and the presence or absence of frost or the amount of frost is detected based on image processing.

[0040] As described above, the first branch passage 51a, the second branch passage 51b, the third branch passage 52a, the fourth branch passage 52b, and the fifth branch passage 52c pass through their respective heat exchangers 10, then merge into a single downstream refrigerant passage 53 and return to the compressor 41. As shown in FIGS. 2 and 3 , the cross-sectional area of ​​the downstream refrigerant passage 53 increases on the way to the compressor 41. After the cross-sectional area increases, the downstream refrigerant passage 53 becomes an expanded passage 54, as shown in FIGS. 2 and 3 . The provision of the expanded passage 54 generates negative pressure when the cross-sectional area of ​​the passage increases, which is expected to draw the refrigerant downstream. This reduces the amount of refrigerant lubricant (refrigerating machine oil) remaining in the heat exchanger 10. The upstream starting point of this expansion passage 54 may be midway through the downstream refrigerant passage 53 as in this embodiment, or may be before merging with the downstream refrigerant passage 53, that is, midway through the first branch passage 51 a, the second branch passage 51 b, the third branch passage 52 a, the fourth branch passage 52 b, and the fifth branch passage 52 c between the downstream refrigerant passage 53 and the downstream end of the heat exchanger 10.

[0041] 2 , the inner diameter φ2 of the first refrigerant passage 51 and the second refrigerant passage 52 in the heat exchanger 10, the inner diameter φ1 of the section of the downstream refrigerant passage 53 upstream of the expanded cross-sectional area portion, and the inner diameter φ3 of the downstream refrigerant passage 53 (expanded passage 54) after the cross-sectional area has been increased may be set as φ1≦φ2<φ3 or φ2≦φ1<φ3, for example, φ1=φ2=5 mm, φ3=6 mm, etc. In this embodiment, quarter-section piping is used for the first refrigerant passage 51 and the second refrigerant passage 52 and for the section of the downstream refrigerant passage 53 upstream of the expanded cross-sectional area portion. Furthermore, five-section piping is used for the downstream refrigerant passage 53 (expanded passage 54) after the cross-sectional area has been increased. A quarter-inch pipe has an outer diameter equivalent to 1 / 2 inch (4 / 8 inch), and a five-inch pipe has an outer diameter equivalent to 5 / 8 inch, with the inner diameter being larger for the five-inch pipe than for the quarter-inch pipe.

[0042] Furthermore, in this embodiment, in addition to or instead of the defrost control by the above-described off-time control (flow path switching control), defrost control by heating control, which melts frost by applying heat to the heat exchanger 10, is also possible. The heating control is performed by a main heater 60 arranged adjacent to the heat exchanger 10. By using the off-time control (flow path switching control) and the heating control together, the defrosting time can be shortened.

[0043] As shown in Figure 3, the main heater 60 branches into a first main heater 61 that is connected to one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) via a switch 45, and a second main heater 62 that is connected to another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14, and fifth heat exchanger 15).

[0044] The first main heater 61 branches into a first branch main heater section 61a that is connected to the first heat exchanger 11 and a second branch main heater section 61b that is connected to the second heat exchanger 12. Furthermore, the second main heater 62 branches into a third branch main heater section 62a that is connected to the third heat exchanger 13, a fourth branch main heater section 62b that is connected to the fourth heat exchanger 14, and a fifth branch main heater section 62c that is connected to the fifth heat exchanger 15. The first branch main heater section 61a, the second branch main heater section 61b, the third branch main heater section 62a, the fourth branch main heater section 62b, and the fifth branch main heater section 62c pass through their respective heat exchangers 10 and then join together to return to the power supply in the control section 40, forming a parallel circuit branched into five sections as a whole. The first branch main heater section 61a, the second branch main heater section 61b, the third branch main heater section 62a, the fourth branch main heater section 62b and the fifth branch main heater section 62c each have a heat-generating portion in the portion arranged along the heat exchanger 10 (at least the overlapping portion in a plan view).

[0045] The control unit 40 controls the switch 45 to selectively activate at least one of the first main heater 61 and the second main heater 62. It is also possible to set both the first main heater 61 and the second main heater 62 to be activated.

[0046] Heating control by the main heater 60 is usually performed in conjunction with defrosting control by off-time control. That is, when the off-time control is in the first state, the first main heater 61 (the first branch main heater portion 61a and the second branch main heater portion 61b) on the side of one heat exchanger A (the first heat exchanger 11 and the second heat exchanger 12) where cooling is continuing is turned off and heating is not performed, and the second main heater 62 (the third branch main heater portion 62a, the fourth branch main heater portion 62b and the fifth branch main heater portion 62c) on the side of another heat exchanger B (the third heat exchanger 13, the fourth heat exchanger 14 and the fifth heat exchanger 15) where defrosting is being performed is turned on and heating is performed. Furthermore, when the off-time control is in the second state, the first main heater 61 (first branch main heater section 61a and second branch main heater section 61b) on the side of one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) where defrosting is being performed is turned on and heating is performed, and the second main heater 62 (third branch main heater section 62a, fourth branch main heater section 62b and fifth branch main heater section 62c) on the side of another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14 and fifth heat exchanger 15) where cooling is continuing is turned off and heating is not performed.

[0047] Furthermore, when the compressor 41 is stopped and all heat exchangers 10 are defrosted simultaneously, both the first main heater 61 (first branch main heater section 61a and second branch main heater section 61b) on one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) side and the second main heater 62 (third branch main heater section 62a, fourth branch main heater section 62b and fifth branch main heater section 62c) on another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14 and fifth heat exchanger 15) side may be turned on, or only the first main heater 61, which has a relatively large amount of frost, may be turned on.

[0048] Furthermore, in this embodiment, heating control can also be performed using a drain pan heater 70 disposed in the drain pan 1. If heating control using the drain pan heater 70 is used in combination with off-time control (flow path switching control), the defrosting time can be further shortened. Furthermore, both the main heater 60 and the drain pan heater 70 may be used during heating control.

[0049] The drain pan heater 70 is branched into a first drain pan heater 71 provided directly below one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) in the drain pan 1, and a second drain pan heater 72 provided directly below another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14, and fifth heat exchanger 15) in the drain pan 1. The drain pan heater 70 may be arranged exposed on the upper surface of the drain pan 1, or may be arranged exposed on the lower surface of the drain pan 1. Alternatively, it may be arranged embedded inside the drain pan 1 between the upper and lower surfaces.

[0050] The first drain pan heater 71 branches into a first branch drain pan heater portion 71a that leads directly below the first heat exchanger 11 and a second branch drain pan heater portion 71b that leads directly below the second heat exchanger 12. Furthermore, the second drain pan heater 72 branches into a third branch drain pan heater portion 72a that leads directly below the third heat exchanger 13, a fourth branch drain pan heater portion 72b that leads directly below the fourth heat exchanger 14, and a fifth branch drain pan heater portion 72c that leads directly below the fifth heat exchanger 15. The first branch drain pan heater portion 71a, the second branch drain pan heater portion 71b, the third branch drain pan heater portion 72a, the fourth branch drain pan heater portion 72b, and the fifth branch drain pan heater portion 72c pass through their respective heat exchangers 10, then merge and return to the power source within the control unit 40, forming a parallel circuit branched into five portions as a whole. The first branch drain pan heater section 71a, the second branch drain pan heater section 71b, the third branch drain pan heater section 72a, the fourth branch drain pan heater section 72b and the fifth branch drain pan heater section 72c each have a heat-generating section located directly below the heat exchanger 10 (at least the overlapping section when viewed in a plane).

[0051] The control unit 40 controls the switch 46 to selectively activate at least one of the first drain pan heater 71 and the second drain pan heater 72. It is also possible to set both the first drain pan heater 71 and the second drain pan heater 72 to operate.

[0052] Heating control by the drain pan heater 70 is also usually performed in conjunction with defrosting control by off-time control. That is, when off-time control is in the first state, the first drain pan heater 71 (first branch drain pan heater portion 71a and second branch drain pan heater portion 71b) on the side of one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) where cooling is continuing is turned off and heating is not performed, and the second drain pan heater 72 (third branch drain pan heater portion 72a, fourth branch drain pan heater portion 72b, and fifth branch drain pan heater portion 72c) on the side of another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14, and fifth heat exchanger 15) where defrosting is being performed is turned on and heating is performed. Furthermore, when the off-time control is in the second state, the first drain pan heater 71 (first branch drain pan heater section 71a and second branch drain pan heater section 71b) on the side of one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) where defrosting is being performed is turned on and heating is performed, and the second drain pan heater 72 (third branch drain pan heater section 72a, fourth branch drain pan heater section 72b and fifth branch drain pan heater section 72c) on the side of another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14 and fifth heat exchanger 15) where cooling is continuing is turned off and heating is not performed.

[0053] Furthermore, when the compressor 41 is stopped and all heat exchangers 10 are defrosted simultaneously, both the first drain pan heater 71 (first branch drain pan heater section 71a and second branch drain pan heater section 71b) on one heat exchanger A (first heat exchanger 11 and second heat exchanger 12) side and the second drain pan heater 72 (third branch drain pan heater section 72a, fourth branch drain pan heater section 72b and fifth branch drain pan heater section 72c) on another heat exchanger B (third heat exchanger 13, fourth heat exchanger 14 and fifth heat exchanger 15) side may be turned on, or only the first drain pan heater 71, which has a relatively large amount of frost, may be turned on.

[0054] In this embodiment, the arrangement of the refrigerant pipes in the heat exchanger 10 is devised to prevent water (liquid) generated during defrosting from dropping into the storage 31 as droplets.

[0055] The first branch passage 51a, which is a refrigerant pipe of the first heat exchanger 11, has an inlet portion 11a and an outlet portion 11b at one end face (referred to as the first end face) of both ends in the longitudinal direction. The first branch passage 51a proceeds along the longitudinal direction from the inlet portion 11a (see longitudinal portion a in FIG. 2 ). At the other end face (referred to as the second end face) of both ends in the longitudinal direction, the first branch passage 51a curves in a U-shape, turns 180 degrees (see direction change portion b in FIG. 2 ), and then continues along the longitudinal direction from the second end face to the first end face. Furthermore, at the first end face, the first branch passage 51a curves and turns 180 degrees (see direction change portion c in FIG. 2 ), and then continues along the longitudinal direction from the first end face to the second end face. This arrangement of longitudinal pipes and curved pipes is repeated until the first branch passage 51a reaches the outlet portion 11b. In this embodiment, the refrigerant pipes are curved horizontally at the second end face to connect adjacent refrigerant pipes in the horizontal direction (see direction change section b in Figure 2), and are curved vertically at the first end face to connect adjacent pipes in the vertical direction (see direction change section c in Figure 2), but the direction of the curves and the arrangement of the longitudinal pipes that are connected to each other can be freely set.

[0056] The second branch passage 51b, which is the refrigerant piping of the second heat exchanger 12, also has an inlet portion 12a and an outlet portion 12b on the first end surface, the third branch passage 52a, which is the refrigerant piping of the third heat exchanger 13, also has an inlet portion 13a and an outlet portion 13b on the first end surface, the fourth branch passage 52b, which is the refrigerant piping of the fourth heat exchanger 14, also has an inlet portion 14a and an outlet portion 14b on the first end surface, and the fifth branch passage 52c, which is the refrigerant piping of the fifth heat exchanger 15, also has an inlet portion 15a and an outlet portion 15b on the first end surface.

[0057] 2, among the multiple heat exchangers 10, the outlet 11b of the first branch passage 51a in the first heat exchanger 11 located at one end in one direction is disposed so as to be located inward in the parallel direction from the center line p of the first heat exchanger 11 relative to the width W in one direction. Here, "inward in the parallel direction" refers to the side on which the adjacent heat exchanger 10 (third heat exchanger 13) is located. In other words, when the distance between the center line p of the outlet 11b in the parallel direction (one direction) and the side surface of the first heat exchanger 11 on the inside in the parallel direction is w1, W1<(W / 2).

[0058] Similarly, the outlet 12b of the second branch passage 51b in the second heat exchanger 12 located at the other end along one direction is also arranged so as to be located on the inner side in the parallel direction of the center line p of the width W in one direction of the second heat exchanger 12. Here, the inner side in the parallel direction also means the side on which the adjacent heat exchanger 10 (fifth heat exchanger 15) is located.

[0059] In this embodiment, the first heat exchanger 11 and the second heat exchanger 12 have symmetrical structures in one direction in terms of the arrangement of refrigerant piping, including inlet sections 11a and 12a, longitudinal piping, curved sections, and outlet sections 11b and 12b. The third heat exchanger 13, the fourth heat exchanger 14, and the fifth heat exchanger 15 have the same specifications in terms of the arrangement of refrigerant piping, including inlet sections 13a, 14a, and 15a, longitudinal piping, curved sections, and outlet sections 13b, 14b, and 15b.

[0060] The outlet portion 11b of the first branch passage 51a is located inward in the parallel direction from the center line p of the width W of the first heat exchanger 11 in one direction, and the outlet portion 12b of the second branch passage 51b is also located inward in the parallel direction from the center line p of the width W of the second heat exchanger 12 in one direction, so that it becomes easier to set the piping so that the downstream refrigerant passage 53 extending from these outlet portions 11b, 12b toward the compressor 41 does not protrude outside the outer edge of the drain pan 1.

[0061] In the conventional technology, all parallel heat exchangers 10 have the same specifications. Therefore, when the outlet 11b of the first branch passage 51a is located inside the center line p of the first heat exchanger 11 relative to its width W, the outlet 12b of the second branch passage 51b is located outside the center line p of the second heat exchanger 12 relative to its width W (closer to the outer edge of the drain pan 1). Furthermore, when the outlet 12b of the second branch passage 51b is located inside the center line p of the second heat exchanger 12 relative to its width W, the outlet 11b of the first branch passage 51a is located outside the center line p of the first heat exchanger 11 relative to its width W (closer to the outer edge of the drain pan 1). Therefore, the downstream refrigerant passage 53 inevitably extends beyond the outer edge of the drain pan 1. If the lower portion of the downstream refrigerant passage 53 is not covered by the drain pan 1, water droplets may fall.

[0062] However, in this invention, the outlet 11b of the first heat exchanger 11 and the outlet 12b of the second heat exchanger 12 are each positioned inward in the parallel direction from the center line p of the width W in one direction, so that the entire downstream refrigerant passage 53 can be easily covered from below with the drain pan 1. This is because, as shown in Fig. 2, a long horizontal distance (corresponding to the distance "W-w1" in Fig. 2) can be ensured between the bent portion 53a provided in the downstream refrigerant passage 53 after all the refrigerant pipes join together and the point where the refrigerant pipes finally join the downstream refrigerant passage 53 (the outlet 12b of the second heat exchanger 12).

[0063] That is, a distance (corresponding to the distance "W-w1" in FIG. 2) between the bent portion 53a of the downstream refrigerant passage 53 (see FIG. 2) and the outlet 12b of the second branch passage 51b, which is the most downstream junction, that is, too close is undesirable in terms of ensuring a smooth flow of refrigerant and in terms of performing work such as welding and brazing. However, by arranging the outlets 11b, 12b of the heat exchangers 10 at both ends on the inner side in the parallel arrangement direction as in the embodiment, a large distance "W-w1" can be ensured. This makes it easy to ensure that the lower portion of the downstream refrigerant passage 53, where frost is likely to form, is reliably covered by the drain pan 1.

[0064] Such an arrangement of the outlets 11b, 12b of the refrigerant pipes is particularly effective in the cooling device 30 that achieves efficient defrosting by having the functions of the off-time control (flow path switching control) and heating control by the main heater 60 or the drain pan heater 70. However, regardless of the content of the defrosting control such as the off-time control (flow path switching control) or heating control, even in the conventional cooling device 30, such an arrangement of the outlets 11b, 12b of the refrigerant pipes can be expected to have a predetermined effect in preventing liquid water generated during defrosting from turning into droplets and falling into the storage tank 31.

[0065] In the above embodiment, five heat exchangers 10 are provided in parallel in the storage room 31, but the number of heat exchangers 10 connected in parallel can be increased or decreased as desired. Also, in the above embodiment, the cooling device of the present invention has been described using a natural convection refrigerator as an example of a commercial refrigerator, but the present invention can be applied to various cooling devices 30 that have heat exchangers 10 connected in parallel. [Explanation of symbols]

[0066] 1 drain pan 3 frames 4 Fans 5 Fixtures 10 Heat exchanger 11 First heat exchanger 12 Second heat exchanger 13 Third heat exchanger 14 Fourth heat exchanger 15 Fifth heat exchanger 30 Cooling device 31 Storage 40 Control Unit 41 Compressor (refrigeration unit) 42 Condenser 43 Expansion valve 44 Switching Device 50 Cooling circuit 51 First refrigerant passage 52 Second refrigerant passage 60 Main heater 70 Drain pan heater

Claims

1. A cooling device having a plurality of heat exchangers (10) in a storage (31), a first refrigerant passage (51) for supplying a refrigerant connected to one heat exchanger (A) among the plurality of heat exchangers (10); and a second refrigerant passage (52) for supplying a refrigerant connected to another heat exchanger (B) having a relatively smaller amount of frost formation than the first heat exchanger (A); a control unit (40) that performs defrosting control to cut off the supply of refrigerant to at least one of the first refrigerant passage (51) and the second refrigerant passage (52) for the purpose of defrosting; Equipped with The plurality of heat exchangers (10) each have a longitudinal shape and are arranged in parallel along one direction so that their longitudinal directions are parallel to each other; The one heat exchanger (A) is a first heat exchanger (11) located at one end along one direction among the plurality of heat exchangers (10), and a second heat exchanger (12) located at the other end along one direction, The cooling device, wherein the another heat exchanger (B) is a heat exchanger (13, 14, 15) other than the first heat exchanger (11) and the second heat exchanger (12).

2. an outlet portion (11b) of the refrigerant pipe (51a) in the first heat exchanger (11) is located inward in a parallel direction from a center line (p) of the first heat exchanger (11) with respect to a width (W) in one direction, and an outlet portion (12b) of the refrigerant pipe (51b) in the second heat exchanger (12) is located inward in a parallel direction from a center line (p) of the second heat exchanger (12) with respect to a width (W) in one direction, 2. The cooling device according to claim 1, wherein the outlet portion (11b) of the first heat exchanger (11) and the outlet portion (12b) of the second heat exchanger (12) are covered below with a drain pan (1).

3. A cooling device having a plurality of heat exchangers (10) in a storage (31), The plurality of heat exchangers (10) each have a longitudinal shape and are arranged in parallel along one direction so that their longitudinal directions are parallel to each other; Among the plurality of heat exchangers (10), an outlet portion (11b) of a refrigerant pipe (51a) in a first heat exchanger (11) located at one end along one direction is located inside in the parallel direction of a center line (p) of the first heat exchanger (11) with respect to a width (W) in one direction, and an outlet portion (12b) of a refrigerant pipe (51b) in a second heat exchanger (12) located at the other end along one direction is located inside in the parallel direction of a center line (p) of the second heat exchanger (12) with respect to a width (W) in one direction, The cooling device is configured such that the outlet portion (11b) of the first heat exchanger (11) and the outlet portion (12b) of the second heat exchanger (12) are covered below with a drain pan (1).

4. 3. The cooling device according to claim 1, wherein the control unit (40) performs either one of an implementation duration control for setting a time period during which the supply of refrigerant to the first refrigerant passage (51) per one defrost control is cut off longer than a time period during which the supply of refrigerant to the second refrigerant passage (52) per one defrost control, and an implementation interval control for setting an implementation interval of the defrost control for the first refrigerant passage (51) shorter than an implementation interval of the defrost control for the second refrigerant passage (52).

5. a first main heater (61) provided in association with the one heat exchanger (A) and a second main heater (62) provided in association with the other heat exchanger (B), 3. The cooling device according to claim 1, wherein the control unit (40) controls at least one of the first main heater (61) and the second main heater (62) to be selectively activated during the defrosting control.

6. The lower portions of the first heat exchanger (A) and the second heat exchanger (B) are covered with a drain pan (1), a first drain pan heater (71) provided directly below the first heat exchanger (A) in the drain pan (1), and a second drain pan heater (72) provided directly below the second heat exchanger (B) in the drain pan (1), The cooling device according to claim 1 or 2, wherein the control unit (40) selectively controls the operation of at least one of the first drain pan heater (71) and the second drain pan heater (72) during the defrosting control.

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