Cooling system

Abstract

A cooling system is configured for arranging a cooling machine and a heat exchanger, for example, inside and outside a heat insulation box. A cooling unit for discharging cooled air by heat exchange using a refrigerant and a heat exchange unit for returning the refrigerant to a coolable condition are connected by a connection portion connecting the upper portions to form an integrated cooling device. The connection portion is arranged so as to straddle an end of a sidewall of the heat insulation box, the cooling unit is arranged inside the heat insulation box, and the heat exchange unit is arranged outside the heat insulation box. During storage or movement by a delivery vehicle, the cooling device is mounted on the heat insulation box. When carrying with hand, only the heat insulation box from which the cooling device is removed can be carried.

Claims

1. A cooling system comprising: a heat insulation box with a lid; and a cooling device having a refrigeration cycle, wherein the cooling device is provided with a cooling unit arranged inside the heat insulation box with the lid and a heat exchange unit arranged outside the heat insulation box with the lid, wherein a connection portion connecting the cooling unit and the heat exchange unit is sandwiched between the lid and a heat insulation box body of the heat insulation box with the lid, and wherein a refrigerant is configured to circulate between the cooling unit and the heat exchange unit via the connection portion to cool an inside of the heat insulation box with the lid, wherein the connection portion accommodates a refrigerant conduit and an electrical wire therein to connect between the cooling unit and the heat exchange unit and wherein the connection portion is configured to support the heat exchange unit and the cooling unit in a manner to hang from the heat insulation box, such that the connection portion is arranged to engage an end portion of a sidewall of the heat insulation box in a straddling manner and is configured such that an entire load of the cooling device is supported by the connection portion.

2. The cooling system as recited in claim 1, wherein the cooling device is configured such that the cooling unit and the heat exchange unit are connected by the connection portion, wherein the cooling unit is provided with a temperature sensor for detecting a temperature in the heat insulation box and a fan motor for sending a cooled air for cooling into the heat insulation box, wherein the connection portion is composed of a connection plate in which piping for the refrigerant and wiring of the temperature sensor and the fan motor are laid therein, wherein the cooling device is configured to be detachable from the heat insulation box, wherein a distance between a portion of a lower end of the heat exchange unit and the connection portion and a distance between a portion of a lower end of the cooling unit and the connection portion are equal.

3. The cooling system as recited in claim 2, wherein, when the cooling device is removed from the heat insulation box with the lid and is placed on a surface, the lower end of the heat exchange unit and the lower end of the cooling unit are level so that the cooling device does not fall.

4. A cooling system for low-temperature transportation, wherein the cooling system as recited in claim 1 is arranged on a cargo bed of a delivery vehicle for physical distribution, wherein during delivery, the cooling unit performs cooling of an inside of the heat insulation box, and wherein when carrying out an item to be transported outside the delivery vehicle, it is configured to be able to lightly transport only the heat insulation box with the lid from which the cooling unit, the heat exchange unit, and the connection portion have been removed and the item to be transported.

5. The cooling system as recited in claim 1, wherein a sub-capillary tube having an inner diameter larger than an inner diameter of a capillary tube is arranged between a filter dryer and the capillary tube in the refrigeration cycle of the cooling device, wherein an inner diameter SD of an inflow end of the sub-capillary tube is larger than an inner diameter CD of an inflow end of the capillary tube, wherein an inner diameter FD of a body portion of the filter dryer is 15 mm to 30 mm, wherein the inner diameter CD of the inflow end of the capillary tube is 0.5 mm to 1.2 mm, and wherein the inner diameter SD of the inflow end of the sub-capillary tube is larger than 0.7 mm.

6. The cooling system as recited in claim 5, wherein an opening area of an inner space of the inflow end of the sub-capillary tube is twice or more than an opening area of an inner space of the inflow end of the capillary tube.

7. The cooling system as recited in claim 6, wherein the filter dryer is provided with the body portion, a joint portion for the sub-capillary tube, and a reduced diameter portion ranging from an outflow end of the body portion of the filter dryer to the reduced diameter of the joint portion, and wherein when a length of the reduced diameter portion is L, the following relation is satisfied: L<2FD.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a cooling system according to an embodiment of the present invention.

(2) FIG. 2 is a cross-sectional view of the cooling system.

(3) FIG. 3 is a perspective view of a cooling device as viewed from a heat exchange unit side of the cooling system.

(4) FIG. 4 is a perspective view of the cooling device as viewed from the cooling unit side of the cooling system.

(5) FIG. 5 is an explanatory diagram of an inner structure of a heat exchange unit of the cooling system.

(6) FIG. 6 is an explanatory diagram of an inner structure of the cooling unit of the cooling system.

(7) FIG. 7 is an inner structure explanatory diagram of a cooling device of the cooling system.

(8) FIG. 8 is a cross-sectional view of a cooling system according to another embodiment of the present invention.

(9) FIG. 9 is a circuit diagram showing an example of a refrigeration cycle of refrigerators/freezers applicable to the cooling system of the present invention.

(10) FIG. 10 is a cross-sectional view of a clogging prevention mechanism applicable to the cooling system according to an embodiment of the present invention.

(11) FIG. 11 shows comparative image diagrams of oil sludge adhesion at a capillary inlet of a conventional device and the present invention, where (A) is a conventional adhesion image and (B) is an adhesion image of the present invention.

(12) FIG. 12 is an image diagram of a clogged condition by oil sludge in the vicinity of an inlet portion of a conventional capillary tube.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

(13) Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

Overview of Cooling Device 11

(14) A cooling system according to this embodiment is a system equipped with a cooling device 11 in which a cooling unit 13 and a heat exchange unit 12 are integrally connected by a connection portion 14, and a heat insulation box 15 to which the cooling device 11 is attached. This system can be applied to transportation at a low-temperature.

(15) The cooling device 11 is, as shown in FIG. 1, a cooling device represented by a compressor refrigerator, and the cooling unit 13 and the heat exchange unit 12 are integrally connected by a connection portion 14. The cooling unit 13 is configured to discharge cooled air by heat exchange using a refrigerant to cool the inside of the heat insulation box 15 to a predetermined temperature. The heat exchange unit 12 is configured to cool the refrigerant by exchanging heat with the outside air. The cooled refrigerant is sent to the heat exchange unit 12 via the connection portion 14. The connection portion 14 connects the upper portion of the heat exchange unit 12 and that of the cooling unit 13, and is accommodating refrigerant conduits 41 and electrical wires 42 (see FIG. 5 and FIG. 6) therein to circulate the refrigerant between the heat exchange unit 12 and the cooling unit 13.

Heat Exchange Unit 12 and Cooling Unit 13

(16) The heat exchange unit 12 and the cooling unit 13 constitute a cooling system used in conventional various refrigerators. As shown in FIG. 5, the heat exchange unit 12 is provided with, as its main configuration, a compressor 21, a condenser 22, a condensing fan 23, and a power supply device 24. As shown in FIG. 6, the cooling unit 13 is provided with, as its main configuration, an evaporator 31, cooling fans 32, an expansion valve (not shown), and a temperature sensor 43.

(17) The operating conditions of the heat exchange unit 12 and the cooling unit 13 are the same as those of a conventional cooling system, but will be briefly described.

(18) First, a refrigerant compressed by the compressor 21 of the heat exchange unit 12 is introduced into the condenser 22. The refrigerant is cooled and liquefied by the air of the condensing fan 23 at the condenser 22.

(19) The liquefied refrigerant is sent to the cooling unit 13 through a capillary tube provided along a refrigerant conduit 41 arranged in the connection portion 14. Note that the capillary tube will be described later in detail by referring to FIG. 9 to FIG. 12.

(20) In the cooling unit 13, the liquefied refrigerant is injected into the evaporator 31 to be vaporized. The vaporized refrigerant draws the heat around the evaporator 31, thereby cooling the evaporator 31. The wind from the cooling fan 32 passes through the cooled evaporator 31 to become cooled air and flows into the heat insulation box 15 to thereby cool the inside of the box.

(21) The refrigerant from the evaporator 31 returns to the compressor 21 of the heat exchange unit 12 via the refrigerant conduit 41 of the connection portion 14 and is compressed again. As described above, a refrigeration cycle for circulating the refrigerant is configured. Note that the reference numeral “26” denotes a vent provided in the casing of the heat exchange unit 12, “33” denotes an air inlet provided in the casing of the cooling unit 13. The power supply device 24 is provided below the compressor 21 provided on the heat exchange unit 12. This power supply device 24 may be a power source from an external power source, may be equipped with a battery, or may be a combination of both. On the heat exchange unit 12 side, a control operation unit 27 is provided. Electrical wires 42 for connecting the heat exchange unit 12 side and the cooling unit 13 side with respect to power and signals are arranged in the connection portion 14 in the same manner as in the refrigerant conduit 41.

(22) The above-described example is a steam compressor, but it can be implemented by changing to other types of refrigerators, such as, e.g., an absorption-type refrigerator and a Sterling freezer, and it can be carried out using a corresponding refrigerant.

Connection Portion 14

(23) The connection portion 14 may take a variety of configurations as long as the heat exchange unit 12 side and the cooling unit 13 side can be connected in terms of refrigerant conduits 41 and electrical wires 42. However, the connection portion 14 is preferably one having stiffness, intensity, and thermal insulation to a degree capable of supporting the heat exchange unit 12 and the cooling unit 13 in a manner hanging from the above.

(24) Further, it is preferable that the heat exchange unit 12 and the cooling unit 13 have the same height. In other words, it is preferable to configure so as not to fall when placed on the floor or the like by removing from the heat insulation box 15 by equalizing the distance between the grounding portion of the lower end of the heat exchange unit 12 and the connection portion 14 and the distance between the grounding portion of the lower end of the cooling unit 13 and the connection portion 14. In cases where the height of the casing of the heat exchange unit 12 and that of the cooling unit 13 are different, it is preferable to configure so as not fall by providing a leg on the shorter side. It is most preferable that the operation can be made by turning on the power immediately after incorporating into the heat insulation box 15 without being tilted from the grounded state.

(25) The refrigerant conduits 41 and the electrical wires 42 are accommodated in a groove formed on the lower surface side of the connection portion 14 and the groove is covered as required, so that the lower surface of the connection portion 14 is made substantially flat. Note that it may be configured such that the connection portion 14 is constituted by a cylindrical member such as a pipe and the refrigerant conduits 41 and the electrical wires 42 are accommodated therein. Further, the connection portion 14 may be configured by a plurality of rod-shaped frame members, and may be implemented by being changed to various configurations. The connection portion 14 may be divided into two or more parts, such as left and right parts.

(26) The refrigerant conduit 41 may be implemented by arranging an insulation member as required. In particular, it is preferable that the connection portion 14 be constituted by a heat insulating plate having high mechanical strength and good heat insulating property made of a material of synthetic resin such as polypropylene or polyethylene which is foamed at a high density and the refrigerant conduits 41 are arranged inside the heat insulating plate. The connection plate 14 may be made of a foamed insulation material, such as, e.g., foamed urethane and foamed silicone. Further, it is appropriate to bury the refrigerant conduits 41 and the electrical wires 42 therein to insulate the sealed state without any gap in the final assembly stage.

(27) As shown in FIG. 1 and FIG. 2, the connection portion 14 is arranged on the end portion of the sidewall 51 of the heat insulation box 15 in a straddling manner in a state in which the cooling unit 13 is arranged inside the heat insulation box 15 and the heat exchange unit 12 is arranged outside the heat insulation box 15. At this time, the connection portion 14 is placed on the upper end face of the sidewall 51 to support the entire load of the cooling device 11 by the connection portion 14.

(28) The connection portion 14 performs the function of arranging the refrigerant conduits 41 and the electrical wires 42 therein and protecting them, the function of connecting the heat exchange unit 12 and the cooling unit 13 to form a single device, and the function of receiving the entire load when mounted on the heat insulation box 15, and connects the inner cooling space and the outside by penetrating the heat insulation box 15. Therefore, the cross-sectional area of the connection portion 14 is preferably as small as possible on the condition that it is possible to perform the respective functions described above. Therefore, when implementing the present invention, the width of the connection portion 14 can be set to be larger than the width of the heat exchange unit 12 and the cooling unit 13. In this embodiment, however, the width of the connection portion 14 is set to be equal to the width of the heat exchange unit 12 and the cooling unit 13. It is also desirable that the width of the connection portion 14 be set to be smaller than the width of the heat exchange unit 12 and the cooling unit 13. Further, it is desirable that the thickness of connection portion 14 be as small as possible, preferably 4 cm or less, more preferably 2 cm, but it should be noted that the present invention is not limited thereto.

Heat Insulation Box 15

(29) The heat insulation box 15 is provided with a box body 50 including a plurality (four in this embodiment) of sidewalls 51 and a bottom 52 constituting the storage space of an item to be transported, and a lid 55 which is openably arranged on the opening of the box body 50. Insulators and other materials are arranged in each portion constituting the heat insulation box 15, and the heat insulation box functions as a heat insulation box when the cooling device 11 is not mounted. Specifically, as the heat insulating material of the heat insulation box 15, urethane foam, polypropylene foam, or the like, is used. In combination therewith, a vacuum insulation material may be used to improve the thermal insulation performance of the cover and the heat insulation box. In cases where the insulation wall is thin, the cooling device 11 may be mounted via a spacer.

(30) The upper end of the sidewall 51 is provided with a recessed portion 53 for accommodating the connection portion 14 (see FIG. 2). Therefore, the cooling device 11 can be mounted on the heat insulation box 15 by simply lowering the cooling device 11 from above the sidewall 51 so that the connection portion 14 fits in the recessed portion 53 in a state in which the cooling unit 13 and the heat exchange unit 12 are arranged inside and outside, respectively. The removal can be easily completed by simply lifting the cooling device 11 upward. At this time, it is preferable that the distance between the opposed wall surface 25 of the heat exchange unit 12 and the opposed wall 35 of the cooling unit 13 be set to be substantially equal to the thickness of the sidewall 51 so that each of the opposed wall surface 25 of the heat exchange unit 12 and the opposed wall 35 of the cooling unit 13 each are in face-to-face contact with the inner and outer surfaces of the sidewall 51. With this, it is possible to suppress the leakage of the cooled air to the outside and to suppress the generation of rattling during the operation. However, in cases where the clearance is about 3 mm or less, the cooled air does not leak excessively, and therefore, the clearance can be considered to be closed with no gap. When the gap between the sidewall and the connection portion becomes a problem, the gap may be filled with a sealing material, such as, e.g., a closed-cell foam sheet and a nonwoven fabric, to ensure the airtightness. With this, the heat insulation effect can be improved and the inflow of the outside air can be shut off by the sealing effect. Therefore, it becomes hardly affected by the temperature change of the outside air and wasteful power will not be consumed, resulting in energy saving.

(31) As described above, it is preferable that the cooling device 11 and the heat insulation box 15 be fixed only by fitting from the viewpoint of improving the workability. However, it is acceptable to adopt a structure that can be temporarily fixed with a fastening tool, such as, e.g., a clip-shaped fastener and a screw.

(32) In the illustrated embodiment, the upper surface of the connection portion 14 and the upper end surface of the sidewall 51 are flush with each other. When the flat lid 55 is placed thereon, the storage space can be closed in a sealed state. However, it may be configured such that a recessed portion is formed on the box body 50 side and no recessed portion is formed on the sidewall 51 side, or such that a recessed portion is provided on both of them. In any event, it is preferable to configure such that the heat insulation box 15 can be closed by the lid 55 so as to maintain the sealed portion in a state in which the cooling device 11 is mounted on the heat insulation box 15.

Low-temperature Transportation

(33) The above-described cooling device 11 and the heat insulation box 15 can be implemented as a low-temperature transportation system capable of delivering an item to be transported whose temperature control is crucial, such as, e.g., foods and chemicals, under proper temperature control and also capable of improving working conditions by reducing a burden on a deliverer.

(34) Specifically, although not illustrated, delivery is performed by loading the cooling system in which the cooling device 11 is mounted on the heat insulation box 15 on a cargo bed of a delivery vehicle. At that time, the cooling device 11 is activated to cool the inside of the heat insulation box 15.

(35) In the final stage of the delivery, the deliverer will carry the heat insulation box 15 to the destination. At that time, the cooling device 11 is removed and only the heat insulation box 15 and the item to be transported are delivered. This eliminates the need to carry the heavy cooling device 11, which in turn can reduce the burden on the deliverer. At that time, the recessed portion of the insulation wall for fitting the connection portion is sealed with a small lid made of insulation materials as a spacer to insulate it, thereby preventing the rising of the temperature in the box.

(36) FIG. 8 shows another embodiment. A partial cutout 56 is formed in the lid 55 to avoid the interference with the connection portion 14. In this situation, there is no need to provide a recessed portion 53 in the heat insulation box 15. Note that when it is desired to use a normal product with no recessed portion or no cutout for the lid 55 and the heat insulation box 15, it can be implemented by mounting a spacer on the upper end surface of the heat insulation box 15.

Modifications

(37) The present invention can be implemented by various modifications. For example, in the embodiment shown in the drawings, it has been described that the mounting of the cooling device 11 is performed vertically on the assumption that the opening of the heat insulation box 15 is located above. However, when the opening is located on the side, it may be implemented as performing the mounting operation of the cooling device 11 laterally. Although the lid 55 has been described as a flat lid, the configuration can be variously changed, such as a configuration with a step protruding downward in the same as in other heat insulation boxes. The lid 55 may be one attached to the box body 50 via a hinge. Although the delivery business including one using a foldable container is exemplified as the application, the present invention can be applied to various applications, such as, e.g., a cooler box for leisure and a storage/transportation box used inside or outside a business premise such as a factory.

(38) Next, referring to FIG. 9 to FIG. 12, an embodiment of a clogging prevention mechanism of a capillary tube in a refrigeration cycle which can be applied to the implementation of the present invention will be described. Note that the clogging prevention mechanism of the capillary tube in the refrigeration cycle can be applied not only to the refrigeration system shown in FIG. 1 to FIG. 8 described above but also to other refrigeration cycles, such as, e.g., a refrigeration cycle in which a cooling unit and a heat exchange unit are integrated.

Overview of Refrigeration Cycle

(39) First, referring to FIG. 9, an example of a refrigeration cycle of a refrigerator/freezer to which the clogging prevention mechanism of the present invention can be applied will be briefly described.

(40) In this refrigeration cycle, a compressor 101, a condenser 103, and an evaporator 106 are connected annularly. Between the condenser 103 and the evaporator 106, a filter dryer 104 and a capillary tube 105 are arranged. A refrigerant circulates in the refrigeration cycle in the refrigerant flow direction indicated by the arrow F while changing the form between a gas state, a liquid state, and a gas-liquid mixture state to exchange heat. The high-temperature and high-pressure refrigerant gas discharged from the compressor 101 is liquefied by being cooled by the condenser 103, flows into the capillary tube 105 through the filter dryer 104 for removing moisture contents and foreign matters in the circuitry. The liquid refrigerant decompressed in the capillary tube 105 is evaporated in the evaporator 106 into a low-pressure gas and sucked by the compressor 101. By repeating this cycle, the condenser 103 becomes high in temperature and the evaporator 106 becomes low in temperature, so that cooling of a refrigerator or a freezer is performed.

(41) The condenser 103 and the evaporator 106 are each provided with a fan 107 to perform the exhaust of warm air and blowing of cold air. In the compressor 101, there exists a refrigerating machine oil 102 for lubricating the inner mechanism, but this refrigerating machine oil 102 circulates in the circuit together with the refrigerant. As described above, the refrigerating machine oil 102 is exposed to high temperature and high pressure during the compressing process by the compressor 101 to be denatured into a tarry oil sludge by being mixed with fine metal powder and adheres to the inner wall of the capillary tube 105 in the vicinity of the inlet thereof where the pressure is rapidly reduced and the flow rate increases. In particular, in a relatively small refrigeration cycle (compressor power 500 W or less), the inner diameter of the capillary tube is generally as small as φ0.5 mm to 1.2 mm, and therefore there are some cases in which the adhesion amount increases with the operation time to finally cause clogging of the capillary tube, resulting in a failure of cooling.

Clogging Prevention Mechanism

(42) The present invention provides a mechanism for preventing clogging of the capillary tube 105 in the refrigeration cycle. The structure will be described mainly referring to FIG. 10. In this embodiment, between the filter dryer 104 and the capillary tube 105 in the refrigeration cycle described above, a sub-capillary tube 108 having an inner diameter greater than the inner diameter of the capillary tube 105 is arranged. That is, the inner diameter SD of the inflow end of the sub-capillary tube 108 is set to be larger than the inner diameter CD of the inflow end of the capillary tube 105.

(43) Specifically, the filter dryer 104 is provided with a body portion 141 whose inner diameter is approximately constant, a reduced diameter portion 142 formed at the outlet side of the body portion, and a joint portion 143 for joining the sub-capillary tube 108. In this embodiment, the structure is shown in which the sub-capillary tube 108 is inserted into the joint portion 143 and fixed thereto by welding, brazing, or the like. However, it may be configured such that the joint portion 143 is inserted into the inside of the sub-capillary tube 108, and other various modifications can be allowable.

(44) The reduced diameter portion 142 is a portion where the inner diameter is narrowed down from the body portion 141 having an approximately constant inner diameter toward the joint portion 143. In the illustrative embodiment, the inflow end of the sub-capillary tube 108 is inserted into the inside of the reduced diameter portion 142, but it may be inserted so as to stop at the part of the joint portion 143.

(45) The outflow end side of the sub-capillary tube 108 is connected to the inflow end side of the capillary tube 105 via a connection tube 109. In this embodiment, the sub-capillary tube 108 and the capillary tube 105 are substantially the same in outer diameter and different only in inner diameter, and therefore, a cylindrical member having a constant inner diameter is used for the connection tube 109. However, the sub-capillary tube 108 and the capillary tube 105 may be different in outer diameter. In this case, it is appropriate to use a cylindrical member having different inner diameters for the connection tube 109. The connection tube 109 may be fixed to the sub-capillary tube 108 and the capillary tube 105 by welding or brazing, but may be fixed by other fixing means. Further, the sub-capillary tube 108 and the capillary tube 105 may be fixed in a butt state or inserted state.

Details of Clogging Prevention Mechanism

(46) As noted above, the present invention is effective in preventing clogging by oil sludge, which is remarkably apparent in a thin capillary tube, and therefore, it is advantageous to apply the present invention to a capillary tube 105 having an inflow end inner diameter CD of 0.5 mm to 1.2 mm. Considering that it is advantageous that the length can be reduced when the inner diameter is shorter provided that the flow resistance caused by the capillary tube 105 is the same, it is more desirable that the inflow end inner diameter CD of the capillary tube 105 be 1.0 mm or less. It is advantageous to apply the present invention to the case in which the inner diameter FD of the body portion 141 of the filter dryer 104 is 15 mm to 30 mm and the inner diameter CD of the inflow end of the capillary tube 105 is 0.5 mm to 1.2 mm.

(47) Here, the inner diameter SD of the inflow end of the sub-capillary tube 108 requires to be larger than the inner diameter CD of the inflow end of the capillary tube 105, but since the sub-capillary tube 108 must not be clogged, the inner diameter SD of the inflow end of the sub-capillary tube 108 also needs to be larger than 0.7 mm, more preferably larger than 0.9 mm.

(48) Particularly, it is preferable that the opening area of the inner space of the sub-capillary tube 108 be set to be approximately twice or more than the opening area of the inner space of the capillary tube 105 by providing a difference in the flow path area therebetween in order to realize a structure in which oil sludge mainly adheres to the inlet portion of the sub-capillary tube 108 and hardly adheres to the inlet portion of the capillary tube 105. Therefore, it is desirable that the inner diameter SD of the inflow end of the sub-capillary tube 108 be equal to or greater than about 1.4 times the inner diameter CD of the inflow end of the capillary tube 105.

(49) Further, since the oil sludge adheres to a range of several centimeters in the vicinity of the inlet portion, from the viewpoint of sacrificially making oil sludge adhere to the sub-capillary tube 108, it is preferable that the length of the sub-capillary tube 108 be 3 cm or more, and it sufficient that it is 5 cm or more. Therefore, from this viewpoint, the length of the sub-capillary tube 108 may be made extremely long. However, the material cost and space are only wasted even if it is set to be long. For this reason, considering the workability such as welding, it is practically advantageous that the length is set to about 10 cm or more and about 30 cm or less.

(50) The present invention controls the adhesion of the oil sludge to the capillary tube 105 by sacrificially making oil sludge adhere to the sub-capillary tube 108. Therefore, at the joint portion of the filter dryer 104 and the sub-capillary tube 108, it is appropriate that the length L of the reduced diameter portion 142 of the filter dryer 104 is twice or less than the inner diameter FD of the body portion 141 of the filter dryer 104, and it is more preferable that the length L be equal to or less than the inner diameter FD. However, this does not preclude that the length of the reduced diameter portion 142 is increased and the inner diameter of the reduced diameter portion 142 is gradually reduced. Further note that although the illustrative embodiment is described in which the inner diameter of the capillary tube 105 is constant in the drawing, it does not preclude that the inner diameter of the capillary tube 105 may be gradually decreased toward the outlet.

(51) As described above, conventionally, oil sludge S adheres to the capillary tube 105 having a small inner diameter and the flow path is clogged (see FIG. 11(A)) at the connecting part between the filter dryer 104 and the capillary tube 105. However, the present invention can provide a clogging prevention mechanism of a capillary tube capable of controlling the adhesion of the oil sludge S in the capillary tube 105 by making the oil sludge S adhere the sub-capillary tube 108 having a larger inner diameter to prevent clogging of the flow path (see FIG. 11(B)).

DESCRIPTION OF SYMBOLS

(52) 11: Cooling device

(53) 12: Heat exchange unit

(54) 13: Cooling unit

(55) 14: Connection portion

(56) 15: Heat insulation box

(57) 21: Compressor

(58) 22: Condenser

(59) 23: Condensing fan

(60) 24: Power supply device

(61) 25: Opposed wall surface

(62) 27: Control operation unit

(63) 31: Evaporator

(64) 32: Cooling fan

(65) 33: Temperature sensor

(66) 35: Opposed wall

(67) 41: Refrigerant conduit

(68) 42: Electrical wire

(69) 50: Box body

(70) 51: Sidewall

(71) 52: Bottom

(72) 53: Recessed portion

(73) 55: Lid

(74) 56: Cutout

(75) 101: Compressor

(76) 102: Refrigerating machine oil

(77) 103: Condenser

(78) 104: Filter dryer

(79) 105: Capillary tube

(80) 106: Evaporator

(81) 108: Sub-capillary tube

(82) 109: Connection tube

(83) 141: Body portion of filter dryer

(84) 142: Reduced diameter portion of filter dryer

(85) 143: Joint portion of filter dryer

(86) CD: Inner diameter of inflow end of capillary tube 105

(87) FD: Inner diameter of body portion 141 of filter dryer 104

(88) SD: Inner diameter of inflow end of sub-capillary tube 108

(89) L: Reduced diameter portion 142 length

(90) S: Oil sludge