WO2007031926A2

WO2007031926A2 - Cooling device for cooling electronic components, as well as electronic consumer appliance equipped with such device

Info

Publication number: WO2007031926A2
Application number: PCT/IB2006/053199
Authority: WO
Inventors: Derk Tiekink
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2005-09-15
Filing date: 2006-09-11
Publication date: 2007-03-22
Also published as: WO2007031926A3

Abstract

The invention relates to a cooling device (5, 105) for cooling electronic components (4, 104) , and an electronic consumer appliance (1, 101) equipped with such cooling device (5, 105) . The cooling device (5, 105) is made of thermally conductive material and comprises at least one first leg (11, 111) , designed to abut the electronic components (4, 104) and at least one second leg (12, 112) , which is hinged or slidably coupled to the first leg (11, 111), so as to enable such second leg (12, 112) to be brought into abutting contact with an adjacent body with good heat dissipating properties such as a housing (2, 102) of the appliance (1, 101) , thereby establishing a thermally conductive bridge. Biasing means (14, 114) may be provided to bias the second leg (12, 112) into abutting engagement with the heat dissipating body.

Description

Cooling device for cooling electronic components, as well as electronic consumer appliance equipped with such device

The invention relates to a cooling device for cooling one or more electronic components in an electronic consumer appliance.

Consumer appliances make more and more use of high power electronic components, which during use produce a considerable amount of heat. To control the temperature within the appliances, this heat must be dissipated to the outside. One known way to cool such appliances is by passing an airflow along the respective components, thereby enabling heat to be dissipated via convection. However, the means to generate such airflow as well as the airflow itself require sufficient space within the appliance, which often may not be available due to ongoing size constraints. Moreover, air slots are needed which affect the appliance's appearance and may interfere with other requirements, such as waterproof specifications. Other cooling configurations are known which make use of heat pipes or water cooling. These configurations are rather expensive and require sufficient space as well. They moreover can be risky due to potential leakage.

From JP2002-232650 a cooling configuration is known, wherein the component to be cooled is connected to a heat sink and wherein a deformable or resilient member of thermally conductive material is inserted in a gap between this heat sink and an adjacent body, more specifically a reflective plate, which has good heat radiation properties. Thanks to its deformable nature, this member can overcome mechanical tolerances in the gap between the heat sink and the adjacent body, and thus establish a good thermal conductive bridge between the two. Consequently, heat generated in the component will be transmitted consecutively to the heat sink, the conductive member and the reflective body, from where it will be dissipated through radiation. A disadvantage of this known cooling configuration is that the thermally conductive member may be difficult to install. Moreover, its well functioning depends on its ability to make good thermally conductive contact between the heat sink and the reflective body, which may require the member to be quite thick where large mechanical tolerances are to be expected. This will reduce its thermal conductivity, as the thermal conductive coefficient of such resilient materials is usually poor.

It is therefore an object of the invention to provide a cooling device for electronic components in electronic consumer appliances, in which the abovementioned disadvantages of the known cooling devices are at least partly avoided. More specifically it is an object of the invention to provide a cooling device of relatively small dimensions, suitable for (but of course not restricted to) application in electronic consumer appliances with limited space and/or no air slots. To that end, a cooling device according to the invention is configured according to the features of claim 1.

With a device according to the invention, a thermally conductive bridge can be established between the or each component to be cooled and some body part of the appliance with good heat dissipating properties, such as the appliance housing, which is able to dissipate heat to the outside world through radiation, convection, conduction or a combination thereof. Thanks to the adjustable second leg, a good thermal contact can be established, regardless of any deviation in the position of the components to be cooled and/or the heat dissipating body, which may for instance be caused by assembly inaccuracies and/or manufacturing tolerances.

Optionally, the cooling device may comprise multiple second legs, which can be adjustably coupled to one or more first legs. This will allow the second legs to contact several heat dissipating bodies or a single body with a complex contact surface. By providing the device with several first legs, more components can be cooled which may be spaced from each other. A multiple leg configuration may furthermore allow the cooling device more freedom to bridge the distance between the or each component to be cooled and the or each heat dissipating body along a more complexly shaped path.

According to one aspect of the invention, the cooling device can furthermore comprise biasing means to bias the or each second leg towards the heat dissipating body. This may facilitate assembly, since the biasing means will 'automatically' force the respective second legs into abutting contact with a heat dissipating body. It may furthermorejielp to establish and maintain a good thermally conductive contact between the two. Preferably the biasing means are configured such that a reaction force acting on the first leg is not transferred to the components to be cooled, so as to prevent the generally fragile connection between these components and a printed circuit board from becoming overloaded.

The adjustable interconnection between the first and second leg can be embodied in different ways, depending on for instance the position of the components to be cooled relative to the heat dissipating body and/or the available space. The or each second leg may for instance be slidably connected to a or the first leg. Such connection takes little space, and may therefore be apt where space around the components is limited. Alternatively, the second leg may be hinged to the first leg. At any rate, the legs and their interconnection is preferably such that a smallest cross section of the thermal conductive bridge formed by said legs is sufficiently large to allow through a certain minimum heat flow.

Because the orientation of the second leg and hence its contacting area with the heat dissipating body will depend on the position of said body relative to the components to be cooled, one of the contacting surfaces of the second leg or the body may be convexly curved, while the other contacting surface is straight. This will allow the second leg to contact the body along a line, in a constant, stable manner, regardless of the relative orientation of said leg.

To even further improve the contact between the legs and the respective components and body, the legs may be covered with a resilient, thermally conductive layer, such as a thermally conductive foam. This will help to increase the respective contact areas, and consequently help to establish a thermal conductive bridge with acceptable heat flow capacity. As the thermally conductive properties of such resilient materials are usually sub optimal, the layer is preferably kept as thin as possible. Likewise, a gap between the contacting areas of the interconnected legs may be lubricated with a thermally conductive fluid or paste, so as to even better ensure good thermal conductive contact between said legs, without hampering the adjustability of the interconnection. Again, the paste layer is preferably as thin as possible, for the same reasons as given above. According to a further aspect of the invention, the legs can be made of a metal with a high thermal conductive coefficient, such as for instance cupper or aluminium. The latter in particular features beneficial properties in that it is reasonably prized and can be readily extruded. Extrusion can be done at relatively low costs, which helps to lower the overall production costs of the cooling device. Extrusion furthermore allows for reasonably accurate dimensioning. Consequently, a gap between the first and second leg may be of small and constant dimensions. This will allow for the abovementioned layer of paste or lubricant to be advantageously thin.

Several embodiments of the cooling device according to the invention are defined in the claims 1 to 13. The invention further relates to an electronic appliance, equipped with the cooling device according to the invention. Due to the cooling device good cooling can be achieved in a limited space, without the risk of leakage (such as with conventional water cooling or heat pipes) and without the necessity for air slots. Moreover, conventional heat sinks may be dispensed with. As such heat sinks generally occupy a considerable surface area of a printed circuit board, space becomes available for additional components. Alternatively, the usually tight space constraints for these circuit boards may be somewhat loosened. Because of the simple and robust design, the device can be easily produced. The device can furthermore be readily assembled, thereby enabling conventional cooling devices such as heat sinks to be replaced, without the necessity of substantial changes to the assembly process. Moreover, thanks to the adjustability and ability to overcome mechanical tolerance build up, the device can be applied in a wide range of appliances and can as such replace conventional, dedicated designed cooling devices.

Further advantageous embodiments of a cooling device according to the present invention and an electronic consumer appliance equipped therewith, are set forth in the dependent claims.

To explain the invention, an exemplary embodiment thereof will hereinafter be described with reference to the accompanying drawings, wherein:

Fig. 1 shows in perspective view, part of an electronic consumer appliance provided with a cooling device according to the invention;

Fig. 2 the cooling device of Fig. 1 in closer detail; Fig. 3 the cooling device of Fig. 2, seen from another angle; and Fig. 4 schematically an alternative embodiment of a cooling device according to the invention.

Figure 1 shows part of an electronic consumer appliance 1, such as for instance a computer, TV or audio/video set. The appliance 1 comprises a housing 2, enclosing a printed circuit board (PCB) 3, which is provided with electronic components 4 of which only two are actually shown. The components 4 are cooled by a cooling device 5, configured to establish a thermally conductive bridge between said components 4 and the housing 2. As best seen in Figures 2 and 3, the cooling device 5 comprises a first leg 11, a second leg 12 that is adjustably connected to the first leg 11, and biasing means 14 for pressing the second leg 12 into contact with the housing 2.

The illustrated first and second leg 11, 12 are of elongated, plate-shaped design and may for instance be extruded from aluminium or some other suitable thermal conductive material. The first leg 11 may at one side be provided with pins 16 or similar fastening means (see Figure 3). This may facilitate mounting of the first leg 11 onto the PCB 3, as shown in Figure 1, wherein the leg 11 extends substantially perpendicular to the PCB 3, with its back resting against the components 4 to be cooled. At its free other side, the first leg 11 is provided with a cylindrical recess 17, arranged to pivotally receive the second leg 12, which to that end is provided with a matching cylindrical edge 18. The hinge construction 15 thus formed allows an angle α between the first and second leg 11, 12 to be varied, wherein the maximum attainable angle α will be limited by the second leg 12 abutting the edge 19 of the recess 17. Preferably, the recess 17 and cylindrical edge 18 are dimensioned so as to closely contact each other over a relatively large surface, so as to enable optimum heat transfer between the first and second leg 11, 12. Optionally, a thermally conductive lubricant may be applied between the recess 17 and edge 18, so as to even better ensure good thermal contact and conductivity between said parts 17, 18.

As furthermore shown in Figures 2 and 3, the end of the second leg 12 facing the housing 2 has a curved or convex shape. Thanks to such curvature, the second leg 12 can stably about the housing 2 regardless the angle α. Of course, a similar result can be obtained by providing the housing with a curved abutting surface and the second leg 12 with a straight abutting surface (not shown). Preferably, the curved surface is covered with a layer 20 of resilient, thermally conductive material, such as for instance a thermally conductive foam. Thanks to such resiliently layer 20, the contact area between the second leg 12 and the housing 2 can be increased, thereby ensuring good heat transfer capacity. Of course, for the same reason, a resilient layer can be applied between the first leg 11 and the electrical components 4 (this embodiment is not shown). Alternatively, a thermally conductive paste may be applied or some other suitable, resilient and/or deformable material, capable of establishing good thermal contact between said surfaces.

As best seen in Figure 3, the biasing means 14 can be configured as an angular plate spring. Preferably, each leg 11, 12 is provided with a bearded ridge 21, 22, which can be integrally formed with the legs 11, 12 and which are arranged to serve as snap-in connection for the plate spring 14. Preferably, the spring 14 is not stronger than needed to press the first and second leg 11, 12 into thermally conductive contact with the components 4 and housing 2 respectively, so as to not overload the relative fragile electronic components 4. For this reason, the biasing spring 14 may be a rather thin plate spring. Of course, other biasing means 14 can be applied, such as for instance one or more torsion springs (not shown). The above described cooling device 1 can be assembled by sliding in the cylindrical edge 18 of the second leg 12 into the recess 17 of the first leg 11 and by subsequently snapping the plate spring 14 into place. Of course, additional locking means may be provided (not shown) to prevent the second leg 12 and/or spring 14 from disassembling during use. Upon mounting the spring 14, the second leg 12 will be pivoted to an extreme position, wherein the angle α is maximal. The cooling device 1 can then be mounted onto the PCB 3 adjacent the components 4 like a normal electronic component, i.e. by hooking the pins 16 into the PCB. Of course, other fastening methods may be provisioned, such as gluing or soldering. Subsequently, the housing 2 can be closed around the PCB. In doing so, the housing 2 will abut the second leg 12 and readjust its position as far as necessary.

Thanks to the above described adjustability of the second leg 12, the exact distance between the PCB 3 and its components 4 on the one hand and the housing 2 on the other hand is not critical. As such, the cooling device 5 according to the invention can effectively overcome mechanical tolerance build up which may be present in many consumer appliances. Moreover, since the cooling device 5 can be mounted like a conventional cooling device (such as for instance a heat sink), this cooling device 5 can readily replace such conventional devices, without substantial changes to the assembly process. Advantageously, the cooling device 5 can be made in a range of standard sizes, so as to form a standard product for general use, to replace dedicated, designed cooling devices.

In the illustrated embodiment, the components 4 to be cooled extend substantially perpendicular to the PCB 3. Therefore, the first leg 11 is positioned substantially perpendicular to the PCB as well, thereby allowing the components 4 to be contacted by the leg 11 over a large area. Hence, the orientation of the first leg 11 may be adjusted to that of the components 4, so as to enable as good a contact as possible. For instance, in case where the components 4 extend substantially parallel to the PCB 3 (so called 'surface mounted devices', e.g. ICs) the first leg 11 may extend substantially parallel to the PCB 3 as well. The pins 16 of the first leg 11 may for that purpose be bent over 90 degrees, so as to facilitate mounting of the device 5 onto the PCB 3. In the given example, the cooling device 5 is shown to extend from the electronic component(s) 4 to the housing 2. This in fact is the preferred embodiment, since the housing 2 can readily dissipate the received heat to the environment, through radiation and/or convection. Optionally, the housing 2 can be provided with an external heat sink 25 (as shown in Figure 1) to increase the effective heat dissipating surface of the housing 2. In appliances 1 where the distance between the component 4 to be cooled and the housing 2 is relatively large, a cooling device 5 according to the invention can still advantageously be applied. In such case, the cooling device 5 may be used to establish a thermally conductive bridge to the nearest part with good heat dissipating properties, for instance a heat sink, or a part that is in thermal conductive contact with the housing 2, be it direct or indirect (via intermediate parts). The cooling device 5 may furthermore be provided with a further second leg 12, which may for instance be hinged to the first leg 11 at its opposite side, so as to establish thermal conductive contact to a different part of the housing 2 (not shown). Figure 4 schematically shows an alternative embodiment of a cooling device

105 according to the invention, wherein corresponding parts have been denoted with corresponding reference numerals, increased with 100. In this embodiment, the first leg 111 comprises a rectangular plate, extending substantially parallel to the PCB 103, on top of one or more components 104 to be cooled. The second leg 112 comprises a similar rectangular plate, mounted on top of the first leg 111 and connected thereto by means of biasing means 114, which are arranged to displace the second leg 112 along the surface of the first leg 111 in longitudinal direction A. The legs 111, 112 may be provided with guiding and/or clamping means (not shown) to keep the first and second legs 111, 112 in close mutual contact, so as to ensure good thermal conductivity. For that purpose, a thermally conductive lubricant may be applied between the contacting surfaces of said legs 111, 112. Furthermore, stoppers and/or locking means may be provided (not shown) to limit the maximum displacement of the second leg 112 and prevent the parts from disengaging. As in the previous embodiment, the surfaces of the legs 111, 112 that contact the components 104, respectively the housing 102 may be covered with a resilient layer of thermally conductive material 120, to increase the contact area.

To install the device 105 onto the PCB 103, the first leg 111 may be provided with pins 116 or the like, as described before. When mounting the PCB 103 in the appliance, the leg 112 will be maximally biased outward (in the direction of arrow A). Upon abutting the housing 102 (or other heat dissipating part of the appliance 101) the second leg 112 will be pushed inward (in the direction of arrow B). Thus, a thermally conductive bridge will be established between the components 104 and the appliance 101 via the first and second legs 111, 112. This embodiment may offer advantages over the previous embodiment, in case there is insufficient space for the pivot construction 15 adjacent the components 104 to be cooled. It furthermore offers the advantage that the biasing means 114 only act upon the first and second legs 111, 112, not upon the fragile components 114. The components 114 can therefore not become overloaded. However, if desired, a small additional biasing means can be provided, to keep the first leg 111 into contact with said component(s) 104.

Of course, the orientation of the cooling device 105 can be altered, for instance to an orientation wherein the legs 111, 112 and the sliding direction A, B extend substantially perpendicular to the PCB 103. Furthermore, the first and second legs 111, 112 may be construed as being at least partially hollow, whereby one of the legs is telescopically received in the other, and wherein biasing means are provided to bias the legs 111, 112 into an extended or elongated position. The invention is not in any way limited to the exemplary embodiments presented in the description and drawing. All combinations (of parts) of the embodiments shown and described are explicitly understood to be incorporated within this description and are explicitly understood to fall within the scope of the invention. Moreover, many variations are possible within the scope of the invention, as outlined by the claims.

Claims

CLAIMS:

1. Cooling device for cooling an electronic component in an electronic consumer appliance by establishing a thermally conductive bridge between said components and at least one adjacent best dissipating body with good heat dissipating properties, the cooling device comprising thermally conductive material and being provided with at least one first leg, designed to abut the component to be cooled and at least one second leg, adjustably coupled to the first leg, so as to enable such second leg to be brought into abutting contact with the at least one heat dissipating body.

2. Cooling device according to claim 1, wherein biasing means are provided, to bias the or each second leg into abutting engagement with the heat dissipating body.

3. Cooling device according to claim 1 or 2, wherein the or each second leg is slidably coupled to a first leg, so as to be extendible relative to this first leg.

4. Cooling device according to anyone of the preceding claims, wherein the or each second leg is hinged to a first leg.

5. Cooling device according to claim 4, wherein the first and second legs have a substantially elongated, plate-shaped form, wherein one of the legs, at one of its longitudinal sides is provided with a cylindrical rod and the other leg is provided with a complementary cylindrical recess, designed to snugly receive the cylindrical rod, so as to ensure good thermally conductive contact between the hinged legs.

6. Cooling device according to anyone of the preceding claims, wherein the first and second leg, at their mutual contacting areas, are lubricated with a thermal conductive fluid or paste, so as to ensure good thermal conductive contact between the first and second leg.

7. Cooling device according to anyone of the preceding claims, wherein one of a contacting surface of the second leg and the heat dissipating body is curved, while the other contacting surface is straight, so that the second leg can abut the body along a line contact, regardless its exact position and/or orientation relative to the body.

8. Cooling device according to anyone of the preceding claims, wherein the first and/or second leg are partly covered with a resilient layer of thermally conductive material, such as a thermally conductive foam, to increase a contact area between the first leg and the components to be cooled and/or the second leg and the heat dissipating body.

9. Cooling device according to anyone of the preceding claims, wherein the first and second leg are made of metal, in particular metal with a high thermal conductive coefficient.

10. Cooling device according to anyone of the preceding claims, wherein the legs are extruded.

11. Cooling device according to anyone of the preceding claims, wherein the legs are provided with snap-in means for fastening the biasing means to the respective legs.

12. Cooling device according to anyone of the preceding claims, wherein the first leg is provided with fastening means for fixating the leg to the component or components to be cooled and/or a printed circuit board on which these components are mounted.

13. Cooling device according to anyone of the preceding claims, wherein the heat dissipating body is the housing of the appliance.

14. Electronic appliance, comprising a printed circuit board with one or more electronic components, mounted in a housing, furthermore comprising a cooling device according to anyone of the preceding claims, wherein the first leg is mounted onto the printed circuit board so as to contact the components thereon and wherein the second leg extends between the first leg and the housing, and is kept into contact with the housing by a biasing force.