EP1774229A2

EP1774229A2 - Refrigerating device and cooling device and peltier-cooling device therefor

Info

Publication number: EP1774229A2
Application number: EP05767562A
Authority: EP
Inventors: David Astrain Ulibarrena; Salvador Manuel GARCÍA SANTAMARÍA; José Manuel LAMUELA ROSANO; José GONZÁLEZ VIAN
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2004-07-23
Filing date: 2005-07-20
Publication date: 2007-04-18
Also published as: DE102004035732A1; WO2006010539A2; WO2006010539A3

Abstract

A Peltier cooling device comprising at least one carrier part (1), a Peltier element (17) and two heat exchangers (9, 14) which are fixed on opposite sides of the carrier parts (1), clamping said Peltier element (17).

Description

Refrigeration device and Peltier cooling device for it

The present invention relates to a Peltier cooling device and a refrigeration device, in wel¬ chem such a cooling device is used.

A Peltier element contains two different electrical conductors, usually semiconductors, connected in series in a circuit, each first end of the two conductors being in contact with each other and with a first heat bath and second ends with a second heat bath. Depending on the direction of a direct current flowing through the Peltier element, heat is conveyed from the first to the second heat bath or vice versa. A problem with the cooling by means of Peltier effect is that cooled and heated side of a Peltier element are close to each other, and that a natural heat flow through the Peltier element is counteracted by cooling by Peltier effect. In order to keep this heat flow small, the temperature difference between the two sides of the Peltier element must be kept as low as possible, and this requires a very close thermal connection of the sides of the Peltier element to the two heat baths with the aid of heat exchangers. Such heat exchangers are therefore usually contained in a Peltier cooler.

In order to make the heat transfer between the heat exchangers and the Peltier element as efficient as possible, it is interesting to pre-assemble these components to ferti¬ gene cooling device and install as a unit in the housing of a refrigerator. However, it is difficult to make the connection between the Peltier cooling device and the housing free of thermal bridges. If one builds successively against the components of the Peltier cooling device into and on a breakthrough in the housing wall, then the heat transfer between the Peltier element and heat exchangers can be impaired, and the efficiency of the finished device is poor.

The object of the invention is to provide a structure for a Peltier cooling device or a refrigeration device, which allows a simple mounting of the cooling device in a housing wall of the refrigeration device and at the same time ensures efficient heat transfer. The object is achieved by a Peltier cooling device according to claim 1 or a refrigeration device according to claim 19.

In order to further simplify the structure while ensuring a uniform clamping of the Peltier element on its entire surface, preferably only a single support member is provided which has an opening in which the Peltier element is arranged.

In order to avoid direct contact between the Peltier element and the insulation material of a refrigeration device housing into which the Peltier cooling device is installed, the opening receiving the Peltier element is preferably surrounded by a sleeve of the carrier part. In order to ensure the thermal contact between Peltier element and heat exchangers, then expediently at least one of the heat exchangers should have a protrusion engaging in the sleeve and touching the Peltier element.

The sleeve is preferably made of a poorly heat-conductive material in order to impede an efficiency-affecting heat flow through the environment of the Peltier element from its warm to its cold side.

Preferably, a shoulder is formed in the sleeve receiving the Peltier element, and the Peltier element is held at that height in the shoulder, whereby the Peltier element or the protrusion engaging in the sleeve can abut against the shoulder To define position of the Peltier element inside the sleeve.

This shoulder is preferably formed approximately centrally in the sleeve, and both heat exchangers have a projection engaging into the sleeve in contact with the pel element.

In order to facilitate a simple assembly of the cooling device according to the invention, the support part preferably has a flange which extends substantially parallel to the sides of the Peltier element between the heat exchangers and to which the heat exchangers are anchored. The locations of the flange to which the heat exchangers are anchored are preferably in the plane of the flange separated from each other. Since it is hardly possible to completely prevent heat from flowing through the flange from the warm to the cold heat exchanger, this arrangement of the anchoring points is intended to make at least the path to be covered long, thereby limiting the heat flow.

The anchoring of the heat exchangers can be achieved in particular by means of anchoring pins, such as screws or bayonet coupling pins, which engage in fastening sleeves formed on the flange.

In order to simplify the installation of the Peltier cooling device in a refrigerator, the mounting sleeves for both heat exchangers are preferably from a same side of the

Flange arranged so that the flange can stand practically directly in contact with one of the heat exchangers, while from the other by one of the

Clamping sleeve receiving space is spaced, which can accommodate an insulating layer of the housing wall at a mounted in a refrigerator Peltier cooling device.

A further simplification of the assembly results when the anchoring pins are inserted into all sleeves from the same side of the flange, in which case the anchoring pins, which anchor a heat exchanger arranged on the inlet side, are initially guided without anchoring engagement through holes in this heat exchanger and with the fastening sleeves in anchoring engagement, while the anchoring pins arranged on the opposite side are guided first without anchoring engagement through the fastening sleeves and are anchoringly engaged on the second heat exchanger.

It is expedient in this case also that the heat exchanger arranged on the inlet side only partially covers the flange, and that the fastening sleeves, which receive the anchoring pins anchoring the other heat exchanger, are arranged in a part of the flange which is not covered by the inlet-side heat exchanger , Thus, these anchoring pins remain freely accessible, even if the introduction-side heat exchanger is mounted, and it is possible to solve only one of the two heat exchangers for maintenance or repair purposes. A considerable intensification of the heat exchange with the Peltier element is achievable by the fact that at least one of the heat exchangers is designed as a thermosyphon, as known from WO99 / 58906, ie the heat exchanger has a cavity which simultaneously deposits a heat transfer fluid in liquid and liquid in gaseous phase ent holds. By evaporating the heat transfer fluid on the warm side of the heat exchanger and the steam flows to the cold side and condenses there, a high thermal power can be transmitted even at low temperature gradients in the heat exchanger. Since the boiling temperature of the heat transfer fluid depends on the pressure prevailing in the dense hollow space pressure and this varies with the ambient temperature, the transport effect by evaporation in a wide temperature range is available.

In order to ensure efficient heat transfer, the heat transfer fluid should have a high heat of evaporation and at the temperatures which occur during normal operation of the cooling device, the highest possible saturation vapor pressure. On the other hand, an excessively high saturation vapor pressure requires a high compressive strength of the heat exchanger, which can only be achieved with high costs, and strong pressure fluctuations in the heat exchanger during operation, which can lead to deformations of the heat exchanger housing, can make the heat-conducting contact between the heat exchanger and Affect Peltier element. Preferably, therefore, a heat transfer fluid is selected, which under normal operating conditions has a saturation vapor pressure in the environment of the atmospheric pressure, in particular between 0.8 and 1.5 bar, or its saturation vapor pressure during non-operation, when the device is at a ambient temperature stored at a maximum of 50 ^° C., does not exceed 5 to 6 bar. A well-suited heat transfer fluid is butane.

In order to make the evaporation of the heat carrier fluid more effective, an inner wall of the cavity is preferably provided with a porous layer in which the heat transfer fluid rises by capillary action, so that a large surface area is available on which it can evaporate.

Such a porous layer is particularly advantageous on a arranged on the cold side of the Peltier element heat exchanger. Here, the porous layer is expediently attached to an inner wall of the cavity facing away from the Peltier element, through which heat flows into the heat exchanger and heat transfer fluid in the Porous layer brings to evaporation, which is then reflected on the Peltier element facing, cooler inner wall of the cavity.

In order to allow an intensive vapor flow from one side of the cavity to the other by formation of convection cells in the vaporous heat transfer fluid, the distance between opposing walls of the interior should be at least 9 mm, preferably between 9 and 15 mm.

The carrier part can be realized simply and inexpensively as an injection-molded part made of plastic.

The above-described Peltier cooling device is preferably mounted in a refrigerator so that its sleeve extends through an insulating layer of the housing of the refrigerator, so that one of the heat exchanger comes to rest on an inner side and the other on an outer side of the housing.

The at least one cavity having a heat exchanger is then preferably arranged in the interior of the refrigerator.

Further features and advantages of the invention will become apparent from the following description of Be¬ embodiments with reference to the accompanying figures. Show it:

1 is an exploded perspective view of a first Aus¬ design of a Peltier cooling device according to the invention;

FIG. 2 is an exploded perspective view of a second embodiment of a Peltier cooling device according to the invention; FIG.

FIG. 3 is an external view of the carrier part of the cooling device of FIG. 2; FIG.

Figure 4 is a section through the cooling device of Figure 2 and a wall of a refrigerator, in which the cooling device is installed.

5 shows an outside view of a refrigeration device with a cooling device according to the invention; and 6 and 7 in each case a section through an outer heat exchanger of the inventive Peltier cooling device

Fig. 1 shows a first embodiment of the cooling device according to the invention in an exploded view. Two carrier parts 1a, 1b injection-molded from a poorly heat-conductive plastic are essentially each constructed from a flat flange, from which four fastening sleeves 6, 7 lying on one side protrude on one side, of which the longer ones are stabilized in each case by triangular wings 8. The two support members 1a, 1b are provided to be mounted spaced apart from each other on a wall of a refrigerator body as shown in the figure.

According to a modification, the two carrier parts 1a, 1b can be connected in one piece and surrounding a central opening 4 by bridging sections 1c drawn as a contoured outline in FIG.

A first heat exchanger 9 comprises a rectangular base plate 10 with four bores 11 arranged on the corners, a solid metallic projection 12 projecting from the front side of the base plate and an opening, not shown in the figure, from the rear side of the base plate known heat dissipation elements. The cuboid projection 12 is dimensioned such that it engages in the opening 4 when the holes 11 of the base plate 10 are aligned with narrower holes 13 of the sleeves 6. For fixing the first heat exchanger 9 on the support part 1 are not shown in the figure screws, which, introduced from the back of the base plate 10 ago, pass through the bores 11 freely and engage in a preformed or selbstgeschnitte¬ nes thread of the holes 13.

A second heat exchanger 14 has the shape of a cuboid made of aluminum with protruding at the front heat exchange ribs 15 and a ab¬ standing on the back, not visible in Fig. 1, but only in the sectional view of FIG. 4 projection 16. The depth of the projection 16 is sufficient to keep clamped a disc-shaped Peltier element 17 between the two projections 12, 16 of the heat exchanger, when both heat exchangers 9, 14 are fixedly mounted on the support parts 1 a, 1 b. From the back of the second heat exchanger 14 are aligned with the sleeves 7 of the support member 1 from four feet 18, each having a central bore 19 (see FIG. 4) whose diameter is smaller than that of an aligned bore 20 of the sleeves 7 sen The second heat exchanger 14 is fixed to the carrier part 1 by means of screws 21, which extend without threaded engagement through the bores 20 and are in engagement with a preformed thread or the threads 21 of the bores themselves cut by the screws 21.

2 shows a second cooling device according to the invention in an exploded view. A carrier part 1 injection-molded from a poorly heat-conductive plastic is essentially constructed from a flat flange 2 with a central opening 4 surrounding by a sleeve 3. The sleeve 3 is composed of two sections 3a, 3b, the section 3a, which is located between the flange 2 and the Ab¬ section 3b, has a larger free cross-section than the latter. The two sections 3a, 3b are connected by a shoulder 5.

At the corners of the section 3a four stubby fastening sleeves 6 are formed. Four further fastening sleeves 7, each stabilized by triangular wings 8, are arranged on the flange 2 near its outer corners. All the sleeves 3, 6, 7 extend on the same side of the flange 2 facing the observer in FIG. 2; the opposite side of the flange 2 is flat.

A first heat exchanger 9 is substantially identical to the heat exchanger 9 of FIG. 1; only its in Fig. 1 elongated base plate 10 is shown in Fig. 2 square dar¬. The block-shaped projection 12 of the heat exchanger 9 is here dimensioned so that it can be inserted into the sleeve 3 and its section 3a aus¬ on essentially the entire free cross section and in the depth to the shoulder 5 or just before. The holes 11 of the base plate 10 are aligned with the holes 13 of the sleeves 6 when the projection 12 is inserted into the sleeve 3.

A second heat exchanger 14 is completely identical to the heat exchanger 14 of Fig. 1. The cross-section of its projection 16 (see Fig. 4) fills the portion 3b of the sleeve substantially free of play; its depth is sufficient to form a disc-shaped Peltier element 17 between the two projections 12, 16 of the heat exchangers. to keep it clamped. Also, the Peltier element 17 is surrounded by the sleeve 3 substantially without play, so that an undesirable heat flow from the warm to the cold side of the Peltier element 17 only by the Peltier element 17 itself or by the poor heat-conducting material of the sleeve 3 take place can.

Fig. 3 shows a view of the concealed in Fig. 2 back of the support member, wherein the projecting from the front sleeves 3, 6, 7 and wings 8 are drawn with dashed outlines. It can be seen on the lower inner wall of the portion 3a two extending from the flange 2 to the shoulder 5 grooves 22, which are provided to receive electrical leads of the height of the shoulder 5 between the projections 12, 16 of the heat exchanger clamped Peltier element 17 ,

Fig. 4 shows the Peltier cooling device of Fig. 2 in the assembled and inserted into a wall 23 of a refrigerator housing state. The wall 23 in each case has a solid outer and inner skin 24 or 25 made of metal or plastic and an intermediate space 26 filled with thermally insulating foam (not shown in the figure). Outer and inner skin 24 and 25 are each provided with openings for passing the projections 3, 6, 7, 8 of the flange 2 and the portion 3b of the sleeve 3. On the outer skin 24, a zusammen¬ hanging opening for all said projections may be provided; the inner skin 25 has an opening 27, the edges of which abut the outside of the shoulder 5, and four holes 28 which are aligned with the holes 19 and 20. By making the sleeves 7 shorter than the portion 3a, when the screws are tightened, the inner skin 25 is slightly tensioned, so that it may be supported by a shoulder (not shown in the figure) between it and the shoulder 5. clamped sealing ring - foam-tight against the shoulder 5.

For mounting the refrigerator, the support member 1 is first placed with engaging in the opening of the wall 23 sleeve 3 on the outer skin 24 of the wall 23 and suitably the second heat exchanger 14 in the interior of the refrigerator. By screwing the carrier part 1 and the heat exchanger 14 by means of the screws 21, both parts are fixed both to one another and to the wall 23. Subsequently, the Peltier element 17 is inserted from the outside into the opening 4 of the sleeve 3, and subsequently the projection 12 of the heat exchanger 9 is inserted into the opening 4. The Base plate 10 of the heat exchanger 9 is screwed tightly to connect the heat exchanger 9 and the support part 1 with each other and at the same time clamp the Peltier element 17 between the polished surfaces of the projections 12, 16 and thus an unimpeded heat flow between the Peltier element 17 and the heat exchangers 9, 14 ensure.

If the heat dissipation element 29 shown only fragmentarily in FIG. 4 does not cover the holes 11 of the base plate 10, it may already be preassembled thereon or preformed in one piece with it when the base plate 10 is fastened to the carrier part 1; otherwise it will be attached to this only after mounting the base plate 10.

As soon as the carrier part 1 and the heat exchanger 9 are connected to one another and thereby the inner skin 25 is pressed against the shoulder 5, the intermediate space 26 can be filled with insulating foam. Since the foam at no point comes into contact with the heat exchangers 9, 14, it does not affect their subsequent disassembly for the purpose of repair or maintenance. Unless the heat dissipation element 29 covers the heads of the screws received in the sleeves 6, 7, a single one of these heat exchangers may be removed in the case of need.

The construction of the heat exchanger 14 mounted inside the refrigerator is explained in more detail with reference to FIG. 4. The solid metal, preferably aluminum, existing projection 15 depends integrally zu¬ together with a parallelepiped housing 30 which carries the ribs 15 on a side facing away from the projection 16 side. A sealed cavity 31 in the interior of the housing contains a heat transfer fluid, e.g. Butane, partly in the liquid, partly in the gaseous state. On the inner side of the cavity 31, adjacent to the ribs 15, a porous layer 32 is introduced, which dips into the liquid heat transfer fluid in its lower region, so that the latter rise in the pores of the layer 32 and thus over the entire height of the Can distribute inner wall.

The porous layer may be formed of various materials. A first possibility is a ceramic material which, for example, in the form of an emulsion of fine particles, spielsweise of alumina or silica gel, is sprayed or painted on the inner wall and with the aid of a binder contained in the emulsion to a solidified solid layer. Alternatively, the layer can also consist of fiber material, for example glass or carbon fiber, natural textile fiber or synthetic fiber resistant to the heat transfer fluid, which is glued to the inner wall or sandwiched between a grid (not shown) and the inner wall ,

Heat taken up by the ribs 15 from the interior of the refrigerating appliance causes the evaporation of heat transfer fluid from the porous layer 32, which subsequently condenses on the opposite inner side of the cavity 31 at the level of the projection 16 cooled by the Peltier element 17 and heats the latter , Thus, the heat flow entering the heat exchanger 14 on a large surface is effectively concentrated on the comparatively small cross-sectional area of the protrusion 16, and in the protrusion 16, a high power flux density is achieved which allows the temperature jump in the Peltier element 17 to be small Efficiency to keep it high.

In order to promote the formation of convection cells in the vapor phase, which promote the heat transport through the cavity 31 significantly, the width of the cavity 31 between the porous layer and the opposite inner side is set to about 10 mm. The other dimensions of the cavity 31 have little effect on its heat transfer capability and may be determined according to convenience aspects, typically between 10 and 20 cm.

In order to ensure sufficient compressive strength of the heat exchanger 9 in the non-cooled state, its walls are made of aluminum with a thickness of at least 5 mm.

Since in the embodiment shown in FIG. 4, the rear side of the housing 30 does not touch the inner skin 25, heat can also penetrate from the interior into the housing 30 on a large part of this rear side. In order to effectively utilize this heat for the vaporization of heat transfer fluid, a porous layer, not shown in the figure, can also be provided on this side of the cavity 31, which, however, eliminates the wall area located at the level of the projection 16, in order to prevent the condensation of the wall Do not affect heat transfer fluids. The heat dissipation element 29 on the outside of the refrigeration device housing can be realized in different ways. 5 shows a perspective view of a refrigeration device according to the invention from the rear, an embodiment in which this heat dissipation element 29 comprises a tank 33 fastened to the here concealed base plate for a heat transfer fluid and a pump, which surrounds the heat carrier fluid by means of a device rear wall mounted cooling coil assembly 34 circulates.

Alternatively, as shown in FIG. 6, the outer heat exchanger 9, like the inner one 14, can be realized as a hollow housing 35, partially filled with gaseous and partly liquid heat carrier fluid with cooling fins 36, whose dimensions and wall thicknesses are the same. The projection 12 is arranged at the lower region of this housing 35 so that heat flowing in via the projection 12 first reaches the supply of liquid heat transfer fluid in the lower region of the inner cavity 37 of the housing 35. This heat reaches the arranged on the opposite side of the housing cooling fins 36 via convection of the liquid heat transfer fluid or by its evaporation and an¬ closing condensation on the cooling fins 36 adjacent wall of the housin ses 35. The heat transfer fluid used in this heat exchanger can, as in the case of the heat exchanger 9 be butane; both heat exchangers are designed so that they tolerate close be an internal pressure of 5 bar, which can occur during storage of the Peltier cooling device at a Um¬ gebungstemperatur of 5O ⁰ C, without plastic deformation or Un¬.

In the embodiment of the outer heat exchanger 9 shown in section in FIG. 7, the projection 12 is arranged at medium height on the wall of the housing 35, above the mirror 38 of the heat transfer fluid in the cavity 37. A porous layer 32 extends from the bottom of the housing Cavity 37 up to the level of the projection 12, so that over the projection 12 incoming heat substantially heats the porous layer 32 and the heat transfer fluid therein. Therefore, a comparatively small heat output flowing in via the projection 12 is sufficient in order to efficiently vaporize the heat transfer fluid in the porous layer 32 and thus remove the heat from the Peltier element touched by the projection 12.

Claims

claims

A Peltier cooling device comprising at least one support part (1, 1a, 1b), a Peltier element (17) and two heat exchangers (9, 14), which on opposite sides of each support part (1, 1a, 1b) form the Peltier element (17) are clamped attached.

2. Peltier cooling device according to claim 1, characterized in that the Peltier element in an opening (4) of the single carrier part (1) is arranged.

3. Peltier cooling device according to claim 2, characterized in that the opening (4) by a sleeve (3) of the support part (1) is surrounded, and that at least one of the heat exchangers (9, 14) engaging in the sleeve Protrusion (12, 16) in contact with the Peltier element (17).

4. Peltier cooling device according to claim 3, characterized in that the sleeve (3, 3 a, 3 b) is formed from poorly heat-conducting material.

5. Peltier cooling device according to claim 3 or 4, characterized in that in the sleeve (3) has a shoulder (5) is formed, and that the Peltier element (17) in the sleeve (3) at the level of the shoulder (5 ) is held.

6. Peltier cooling device according to claim 5, characterized in that the Schul¬ ter (5) is formed approximately centrally in the sleeve (3), and that the second heat exchanger (14) in the sleeve (3) engaging projection (16) in contact with the Peltier element (17).

7. Peltier cooling device according to one of the preceding claims, characterized ge indicates that the support part (1) has a between the heat exchangers (9, 14) extending flange (2) on which the heat exchanger (9, 14) to each ¬ Weil are anchored in the plane of the flange spaced apart locations.

8. Peltier cooling device according to claim 7, characterized in that on the flange (2) fixing sleeves (6, 7) are formed, in which the two heat exchanger (9, 14) engage anchoring anchoring pins.

9. Peltier cooling device according to claim 8, characterized in that the fastening sleeves (6, 7) for both heat exchangers (9,14) from a same side of the

Protrude flange (2).

10. Peltier cooling device according to claim 8 or 9, characterized in that the anchoring pins in all mounting sleeves (6, 7) are introduced from a same side of the flange (2) ago, and that a first (9) of the heat exchanger

(9; 14) anchoring pins are first guided without anchoring engagement through holes (11) of the first heat exchanger (9) and with the zu¬ ordered mounting sleeve (6) in anchoring engagement, while the second heat exchanger (14) anchoring anchoring pins (21 ) are initially performed without anchoring engagement by the respectively associated fastening sleeve (7) and are anchoringly engaged on the second heat exchanger (14).

1 1. Peltier cooling device according to claim 10, characterized in that the first heat exchanger (9) the flange (2) only partially covered, and that the fastening sleeves (7), which anchoring the second heat exchanger (14) anchoring ¬ rungsstifte (21) record, in a non of the first heat exchanger (9) ü- berdeckten part of the flange (2) are arranged.

12. Peltier cooling device according to one of claims 8 to 11, marked thereby, that the anchoring pins are screws (21) or bayonet locking pins.

13. Peltier cooling device according to one of the preceding claims, characterized ge indicates that at least one of the heat exchangers (9, 14) has a cavity (31, 37) which contains a heat transfer fluid simultaneously in the liquid and in gaseous phase.

14. Peltier cooling device according to claim 13, characterized in that in the cavity (31, 37) filled heat transfer fluid has a saturation vapor pressure of 0.8 to 1, 5 bar under normal operating conditions of the cooling device.

15. Peltier cooling device according to claim 13 or 14, characterized in that the heat transfer fluid has a saturation vapor pressure of less than 6 bar at 50 ° C.

16. Peltier cooling device according to claim 13, 14 or 15, characterized in that the cavity (31, 37) is provided on an inner wall with a porous layer (32), in which heat transfer fluid rises by capillary action.

17. Peltier cooling device according to claim 16, characterized in that the porous layer (32) is attached to an inner wall of the cavity (31) facing away from the Peltier element (17).

18. Peltier cooling device according to one of the preceding claims, characterized ge indicates that the carrier part (1) is integrally molded from plastic.

19. Refrigerating appliance with a surrounding an interior heat-insulating housing, characterized by a Peltier cooling device according to one of the preceding

Claims in which an insulating layer (26) of the housing extends between the heat exchangers (9, 14).

20. Refrigerating appliance according to claim 19, wherein the Peltier cooling device is a Kühlvorrich- device according to one of claims 3 to 6, the sleeve (3) in the insulating layer

(26) is embedded.

21. Refrigerating appliance according to claim 19 or 20, wherein the Peltier cooling device is a cooling device according to one of claims 13 to 17, characterized in that the at least one cavity (31) having a heat exchanger (14) in

Interior of the refrigerator is arranged.