JP2006090684A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator providing quick freezing by a very low temperature while suppressing cooling nonuniformity by effectively using the cold generated by a Stirling refrigerating machine. <P>SOLUTION: In the refrigerator provided with a refrigerating cycle 20, and the Stirling refrigerating machine 23 having a heat exchanger 31 thermally coupled to a heat absorbing part 23a, a freezing chamber 5 and a refrigerating chamber 7 are cooled by the refrigerating cycle, and one part of a refrigerant circulation pipe 43 sealing a coolant to comprise a close loop, and thermally coupled to the heat exchanger 31 thermally coupled to the heat absorbing part 23a of the Stirling refrigerating machine 23 is extended to cool the freezing chamber 5. It is characterized by that the coolant is circulated by providing a vertical interval in a heat exchange passage 39 of the refrigerant circulation pipe 43 thermally connected to the heat exchanger 31, and extending the refrigerant circulation pipe 43 to a cooling plate 47 arranged in a position lower than the heat exchanger 31 in the freezing chamber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigerator having a refrigerant compression refrigeration cycle, and particularly to a refrigerator including a Stirling refrigerator as an auxiliary refrigerator.

  Conventional refrigerators generally employ a refrigeration cycle using a compressor. This refrigeration cycle obtains a predetermined cooling capacity by repeatedly condensing and evaporating chlorofluorocarbon as a refrigerant. However, since chlorofluorocarbon has a risk of destroying the ozone layer, its use is limited. Therefore, in recent years, hydrocarbon refrigerants such as isobutane are used as refrigerants instead of CFCs.

  However, in a refrigerator using a refrigeration cycle using such a compressor, for example, when rapidly freezing food, a large compressor is required to obtain the necessary cooling capacity, which increases power consumption and increases running costs. It is. Moreover, when it is necessary to set the refrigerator temperature to an extremely low temperature of −30 ° C. or less, it is difficult to cope with the cooling capacity of the refrigeration cycle by the refrigerant compression compressor.

  Then, it replaced with the above-mentioned refrigerating cycle and the refrigerator using the Stirling refrigerator using a reverse Stirling cycle is proposed (for example, patent documents 1).

  Stirling refrigerators use an inert gas such as helium that does not destroy the ozone layer as the working medium. By operating the displacer and piston by external power, the working medium is repeatedly compressed and expanded, generating heat and endotherm. Is to do.

  This Stirling refrigerator can obtain a very low temperature of about −50 ° C. from an endothermic part called a cold head. However, due to the limitation of the shape and size of the internal heat exchanger provided inside the refrigerator. Since the surface area of the heat absorption part is limited, it is difficult to rapidly cool the inside of the refrigerator by discharging cold air using this as a cold source.

  Moreover, the refrigerator which combined the refrigerating cycle and the Stirling refrigerator is disclosed as what solves the fault which each of the refrigerating cycle using a compressor, and a Stirling refrigerator (for example, patent document 2).

  This refrigerator has a refrigeration cycle using a Stirling refrigerator that cools the freezer compartment and a compressor that cools the freezer compartment and the refrigerator compartment, and keeps the freezer compartment cooled to a normal freezing temperature (for example, −18 ° C.). In this case, after cooling to the freezing temperature by a refrigeration cycle, the temperature is maintained by a Stirling refrigerator. On the other hand, in the case where the freezing room is cooled and held at an extremely low temperature of −30 ° C. or lower, the freezing room is pre-cooled to a normal freezing temperature by a refrigeration cycle, and then the Stirling refrigerator is started and the normal freezing temperature is −30 ° C. Cool to the following temperature and maintain that temperature.

  However, as a means for preserving the deliciousness of food, it is known to quickly freeze the food. In such a case, in the refrigerator configured as described above, cooling from room temperature to the freezing temperature at which the food freezes is performed. It will be performed only by the refrigerant compression refrigeration cycle, and the capacity of the Stirling refrigerator that can generate cold at -30 ° C. or lower has not been effectively utilized.

  Therefore, the present applicant cools the freezing room and the refrigeration room by forcibly circulating the cold air generated by the evaporator of the refrigeration cycle with a fan, and also forms a closed loop shape thermally coupled to the heat absorption part of the Stirling refrigerator. The refrigerator which extended the refrigerant | coolant circulation pipe into the freezer compartment and formed the mounting shelf was proposed previously (Japanese Patent Application No. 2004-73550).

In this refrigerator, in addition to cooling the freezer compartment by the refrigerating cycle, the secondary refrigerant cooled by exchanging heat with the heat absorption part of the Stirling refrigerator is passed through the refrigerant circulation pipe extending into the freezer compartment space. By naturally circulating using the change in specific gravity due to the temperature difference of the temperature, it is possible to efficiently transfer the cold heat generated from the heat absorption part of the Stirling refrigerator with a small surface area to the freezer compartment, forming a cryogenic space in the freezer compartment Therefore, the food in the freezer can be rapidly frozen.
Japanese Patent Laid-Open No. 7-180921 JP 2000-337747 A

  However, in the refrigerator having the above-described configuration, the cold air generated by the evaporator of the refrigeration cycle blows out from the back side of the freezer compartment toward the front side, and high temperature outside air enters the freezer compartment from the front side by opening and closing the freezer compartment door. In order to enter, the food stored in the freezer compartment has a problem of causing so-called cooling unevenness that is frozen earlier as it is placed on the back side. In particular, in the refrigerator having the above configuration, since the circulation direction of the secondary refrigerant is not fixed, the circulation path of the secondary refrigerant cooled by the Stirling refrigerator is not constant, and it is difficult to control the cooling unevenness.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a refrigerator capable of quick freezing while suppressing uneven cooling of foods and the like.

The refrigerator of the present invention includes a refrigerant compressor, a condenser, a decompression device, a refrigeration cycle in which an evaporator is connected in an annular shape, and a Stirling refrigerator having a heat exchanger thermally coupled to the heat absorption part,
The refrigerant that cools the freezer compartment and the refrigerator compartment by the refrigeration cycle, encloses a cooling medium, forms a closed loop, and is thermally coupled to a heat exchanger that is thermally coupled to the heat absorption part of the Stirling refrigerator. In the refrigerator that extends a part of the circulation pipe and cools the freezer compartment, a difference in height is provided in the heat exchange flow path of the refrigerant circulation pipe that is thermally connected to the heat exchanger, and the refrigerant circulation pipe is disposed in the freezer compartment. The cooling medium is circulated by extending to a cooling plate disposed at a lower position than the heat exchanger.

  In the refrigerator of the present invention, the refrigerant circulation pipe is provided with a height difference in the heat exchange passage and connected to the heat exchanger, and the refrigerant circulation pipe portion extending from the heat exchange passage disposed below to the freezer compartment is By providing the cooling plate portion below the heat exchanger and providing the pipe with a height difference, the circulation direction of the cooling medium sealed inside can be made constant and stable natural circulation can be achieved. As a result, it is possible to smoothly transmit the cold heat of about −50 ° C. generated from the heat absorption part of the Stirling refrigerator into the freezer compartment, and quick freezing with reduced cooling unevenness as described above becomes possible.

  In the refrigerator of the present invention, the back surface of the cooling plate is inclined so as to increase from the front side to the back side of the freezer compartment, and the circulation path of the cooling medium connected to the heat exchanger at a low position is from the front side of the freezer compartment to the back side. It is preferable that it is arranged so as to circulate while meandering laterally to the side.

  In this way, the circulation path of the cooling medium connected to the heat exchanger at a low position is arranged in the freezer compartment so that it gradually becomes higher from the near side to the far side of the freezer compartment. The cooled cooling medium flows from the front side of the refrigerator to the back side, and the heat is taken away. Therefore, the near side is cooled earlier than the back side, and the above-described cooling unevenness can be eliminated. Moreover, the cooling medium that has been deprived of cold and has a low specific gravity flows smoothly to the refrigerant circulation pipe on the back side disposed at a high position.

  According to the present invention, the cryogenic cooling medium cooled by the heat exchanger of the Stirling refrigerator is caused to flow down to the cooling plate portion disposed below the heat exchanger, and the flow is urged in a certain direction. Since the cooling medium can be smoothly circulated and the cooling medium can be circulated from the front side to the back side of the freezer compartment, quick freezing can be performed while suppressing uneven cooling of foods stored in the freezer compartment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a refrigerator (1) according to an embodiment of the present invention, FIG. 2 is a sectional view showing a state in which a Stirling refrigerator (23) is attached to a refrigerator room (21), and FIG. 4 is an exploded perspective view of the heat exchanger (31), FIG. 4 is a cross-sectional view showing a state in which the heat exchanger (31) is attached to the heat absorbing portion (23a), and FIG. 5 is a view of circulation of the cooling medium enclosed in the refrigerant circulation pipe (43). It is a perspective view of a freezer compartment (5) shown.

  The refrigerator (1) of this embodiment arranges a freezer compartment (5) and a refrigerator compartment (7) up and down by arranging a heat insulation partition plate (4) in a storage space inside a heat insulation box whose front is open. And a dedicated open / close door (5a) (7a) is provided at the front opening of each storage chamber to close it.

  An evaporator (11) and a blower fan (13) are respectively disposed in the vicinity of the upper portion of the refrigeration space, and cool air generated from the evaporator (11) is cooled by the blower fan (13). Cooling is performed by circulating the refrigeration space and the refrigeration space through a duct (9) provided with outlets (9a) and (9c) and suction ports (9b) and (9d) that open to the upper and lower portions of the rear surface.

  A machine room (17) space is formed at the lower back of the refrigerator compartment (7), and a refrigerant compressor (19) for supplying refrigerant to the evaporator (11) through a condenser and a capillary tube (not shown). And the refrigeration cycle (20) is configured. In addition, a refrigerator room (21) is provided at the upper corner of the back of the freezer room (5), and a Stirling refrigerator (23) is arranged in the interior so that the heat absorption part (23a) faces upward, and is elastic. It is supported in a vibration-proof state by the support member (25).

  The Stirling refrigerator (23) shown in FIG. 2 is a free-piston type Stirling refrigerator in which, for example, a piston and a displacer are housed in a cylinder and a linear motor is used to drive the piston. The temperature of the heat absorption part (23a) of a refrigerator (23) becomes low, and the temperature of an exhaust heat part (23b) becomes high.

  The exhaust heat part (23b) is connected to the radiation fins (27) and performs heat exchange with the outside air blown from the outside fan (29) to cool the exhaust heat part (23b). The heat absorption part (23a) is adapted to transmit cold energy to a cooling medium thermally coupled via the heat exchanger (31).

  As shown in FIG. 3, the heat exchanger (31) includes an upper member (33) and a lower member (35), and sandwiches a U-shaped heat exchange channel (39). Yes. Specifically, the upper surface of the lower member (35) is provided with two fitting grooves (35a) that are inclined surfaces and extend in the same height direction at different heights, and the heat exchange channel (39). Is supposed to hold. In addition, the lower surface of the upper member (33), that is, the mating surface with the lower member (35), also has a fitting groove (33a) at a position corresponding to the fitting groove (35a) provided in the lower member (35). Thus, the upper member (33) and the lower member (35) are provided with a height difference so as to sandwich the heat exchange channel (39) in a surface contact state and are thermally coupled.

  On the lower surface of the lower member (35), a cylindrical part (37) that fits with an endothermic part (23a) of the Stirling refrigerator (23) with an appropriate gap is provided integrally. A plurality of notch grooves (37a) extending upward are provided. Moreover, the outer peripheral surface of the cylinder part (37) is provided in the taper shape whose diameter becomes thin as it goes below, and the thread groove (37b) is screwed by this taper part.

  As shown in FIG. 4, such a heat exchanger (31) has a cylindrical part (37) fitted with a heat absorbing part (23a) of a Stirling refrigerator (23), and an outer side of the cylindrical part (37) on the lower end side. A nut (41) having a screw hole of the same size as the diameter and screwed into the screw groove (37b) is tightly coupled to and thermally coupled to the Stirling refrigerator (23).

At that time, the cylindrical portion (37) is provided with a notch groove (37a) together with the taper.
Since the tightening pressure of the cylindrical portion (37a) can be evenly applied in the circumferential direction by the rotation of the nut (41), the tightening pressure is locally applied to deform the heat absorbing portion (23a), and the Stirling refrigerator (23) is There is no damage. Furthermore, since the tightening pressure of the cylinder part (37) can be easily adjusted by adjusting the rotation amount of the nut (41), the tightening pressure of the cylinder part (37) is managed by the rotation amount of the nut (41). And the heat absorption part (23a) is deformed to damage the Stirling refrigerator (23), or the heat absorption part (23a) and the heat exchanger (31) are insufficiently tightened. Problems such as an increase in thermal resistance can be easily solved. Further, since the heat exchanger (31) is fixed to the Stirling refrigerator (23) by tightening the nut (41) as described above, the tightening pressure can be easily adjusted even after the fixing.

  Both ends (39a) and (39b) of the heat exchange channel (39), that is, the inlet / outlet (39a) and (39b) of the heat exchange channel (39) are connected to the refrigerant circulation pipe (43), By enclosing a secondary refrigerant such as carbon dioxide or hydrocarbon as a cooling medium, the refrigerant circulation pipe (43) has a closed loop shape and is thermally coupled to the heat exchanger (31).

In that case, the entrance / exit (39a) (39b) of the heat exchange flow path (39) leads out from the refrigerator side surface side. Thus, by arranging the inlet / outlet (39a) (39b) of the heat exchange channel (39),
The refrigerant circulation pipe (43) arranged in the refrigerator room (21) can be provided at a short distance, and the cold heat leaks from the cooling refrigerant cooled in the heat exchange flow path (39) to other than the freezer room space. This can be reduced.

  As shown in FIG. 5, a part of the refrigerant circulation pipe (43) extends into the free space of the freezer compartment (5) to form a cooling plate part (43a), and the heat exchanger (31) The cooling plate (47) which is disposed further downward and spaced from the bottom surface of the freezer compartment (5) is joined to the back surface of the cooling plate (47) which forms the inner shelf of the freezing space. More specifically, the cooling plate (47) is inclined with a gradient of about 5 ° so that the back surface thereof becomes higher from the front side (freezer compartment door (5a) side) to the back side of the freezer compartment (5). The refrigerant circulation pipe (43) connected to the lower end (39b) of the heat exchange channel (39) is meandering from the near side to the far side of the refrigerator in the lateral direction, and the back surface of the cooling plate (47). Then, the refrigerant circulation pipe (43) has a closed loop shape by being connected to the upper end (39a) of the heat exchange channel (39).

  In other words, the freezer compartment (5) near side and the lower end (39b) of the cooling plate portion (43a) are connected, and the rear side and the upper end (39a) are connected, so that the heat exchanger The circulation path of the cooling refrigerant connected at a low position with (31) is arranged to circulate while meandering in the lateral direction from the near side to the far side of the freezer compartment (5).

  The surface of the cooling plate (47) may be a horizontal surface as shown in FIG. 5 or a surface parallel to the back surface of the cooling plate (47). When the surface of the cooling plate (47) is a surface parallel to the back surface, the gradient is about 5 °, so that the placed food does not fall down.

  Further, by disposing the cooling plate (47) at a position separated from the bottom surface of the freezer compartment (5), it is possible to prevent cold heat from leaking outside through the heat insulating partition plate on the bottom surface of the freezer compartment via (4). Can do.

  In the refrigerator (1) of the present embodiment, the refrigerator compartment (7) is cooled to a refrigeration temperature, for example, + 1 ° C., and the freezer compartment (5) is frozen at a freezing temperature, for example, −18 ° C. When the normal cooling operation for cooling and holding is performed, only the refrigeration cycle (20) is operated without operating the Stirling refrigerator (23).

  Then, by rotating the blower fan (13) simultaneously with the cooling operation, the cool air cooled by the evaporator (11) is blown out into the freezer compartment (5) from the outlet (9c) to cool the interior, Circulate back to the evaporator (11) from the mouth (9d). Moreover, about a refrigerator compartment (7), by controlling opening / closing of the damper (10) provided in the blower outlet (9a) for refrigerator compartment, a part of cold air which passed the evaporator (11) is made into a refrigerator compartment (7). ) To cool to a predetermined temperature.

  On the other hand, when performing quick freezing of food, the Stirling refrigerator (23) is operated simultaneously with the operation during the normal operation. The cold heat generated from the Stirling refrigerator (23) is transmitted to the cooling medium enclosed in the refrigerant circulation pipe (43) through the heat exchanger (31) attached to the heat absorption part (23a), and is applied by the thermosyphon principle. Transport to freezing space.

  That is, the cooling medium in the heat exchange flow path (39) cooled through the heat exchanger (31) attached to the heat absorption part (23a) of the Stirling refrigerator (23) is liquefied and its specific gravity increases. Thus, it flows out from the lower end (exit) (39b) of the heat exchange channel (39) and flows into the cooling plate (43a) from the near side of the freezer compartment (5). At that time, since the cooling plate portion (43a) is arranged below the heat exchanger (31), the cooling medium smoothly flows into the cooling plate portion (43a) by its own weight.

  And the cooling medium which flowed into the cooling plate part (43a) from the near side of the freezer compartment (5) exchanges heat with the cooling plate (47) joined to the cooling plate part (43a) to evaporate it. Cool gradually from side to back. Then, since the specific gravity of the cooling medium that has released the cold heat to the cooling plate (47) is reduced by vaporization, a flow that rises in the refrigerant circulation pipe (43) is generated, and the heat exchange flow path (39) From the upper end (inlet) (39a), the heat exchange channel (39) flows into the heat exchange channel (39a), and the cooling is repeated again by receiving the cold generated from the heat absorbing part (23a).

  In this way, the cooling medium in the refrigerant circulation pipe (43) cooled by the Stirling refrigerator (23) always circulates in the freezing chamber (5) from the front side to the back side in a fixed direction to release cold heat. Therefore, it is possible to eliminate the temperature unevenness that the temperature on the front side of the freezer compartment (5) increases due to the opening and closing of the freezer compartment door (5a). In addition, the food placed on the cooling plate (47) also has a lower temperature on the front side and heat exchange is sequentially performed on the back side, and conversely, the cold air generated by the evaporator (11) blows out from the back side. Therefore, uneven cooling can be eliminated.

  In the present embodiment, the cooling plate portion (43a) that is a part of the refrigerant circulation pipe (43) is joined to the back surface of the cooling plate (47), but the present invention is not limited to this, For example, the flow path for circulating the cooling medium may be integrally provided on the back side of the cooling plate (47).

  INDUSTRIAL APPLICABILITY The present invention is useful as a refrigerator equipped with a quick freezing configuration that suppresses uneven cooling.

It is a longitudinal section structure figure of a refrigerator concerning one embodiment of the present invention. It is sectional structure drawing which shows the attachment state of a Stirling refrigerator. It is a disassembled perspective view of a heat exchanger. It is sectional drawing which shows the attachment state of a heat exchanger, (a) is before attachment, (b) is a figure which shows after attachment. It is a perspective view of the freezer compartment showing circulation of a cooling medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator 5 Freezing room 7 Refrigeration room 9 Duct 9a, 9c Outlet 9b, 9d Inlet 11 Evaporator 19 Refrigerant compressor 20 Refrigerating cycle 23 Stirling refrigerator 23a Endothermic part 31 Heat exchanger 37 Cylindrical part 37a Notch 37b Screw groove 39 Heat exchange flow path 39a Upper end (inlet) 39b Lower end (outlet)
41 Nut 43 Refrigerant circulation pipe 43a Cooling plate portion 47 Cooling plate

Claims (4)

A refrigeration cycle in which a refrigerant compressor, a condenser, a decompression device, and an evaporator are annularly connected, and a Stirling refrigerator having a heat exchanger that is thermally coupled to the heat absorption unit,
The refrigerant that cools the freezer compartment and the refrigerator compartment by the refrigeration cycle, encloses a cooling medium, forms a closed loop, and is thermally coupled to a heat exchanger that is thermally coupled to the heat absorption part of the Stirling refrigerator. In the refrigerator that extends a part of the circulation pipe and cools the freezer compartment,
The refrigerant circulation pipe thermally connected to the heat exchanger is provided with a height difference, and the refrigerant circulation pipe is extended to a cooling plate disposed at a position lower than the heat exchanger in the freezer compartment for cooling. A refrigerator characterized by circulating a medium.   The back of the cooling plate is inclined so that it rises from the front side to the back side of the freezer, and the circulation path of the cooling medium connected to the heat exchanger at a low position meanders laterally from the front side to the back side of the freezer The refrigerator according to claim 1, wherein the refrigerator is arranged to circulate while being circulated.   The heat exchanger has a cylindrical portion that extends downward from the bottom surface and fits with the heat absorbing portion of the Stirling refrigerator, and on its outer peripheral surface, a taper that becomes narrower as it goes downward and a lower end that is provided in a plurality of strips on the outer peripheral surface. A notch groove and a screw groove extending upward from the screw groove are provided, and the heat exchanger is fixed to the heat absorption part of the Stirling refrigerator by tightening a nut screwed into the screw groove. The refrigerator according to 1 or 2. The Stirling refrigerator is disposed at the upper corner of the back of the freezer compartment so that the heat absorption part faces upward, and the inlet / outlet of the heat exchange channel is led out from the side of the refrigerator. The refrigerator in any one.

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