DE102015205985A1 - Cooling device for installation-independent cooling - Google Patents

Abstract

The invention relates to a cooling device for cooling a housing, comprising: a surface to be cooled (2); - A plurality of star-shaped on the surface to be cooled (2) arranged elongated web-like projecting cooling fin structures (4, 4a, 4b), which are aligned to a center region (Z) of the surface to be cooled (2).

Description

State of the art

The invention relates to cooling devices, in particular passive cooling devices, which are formed on a surface with rib structures. In particular, the present invention relates to the arrangement of cooling fin structures on surfaces to be cooled.

To remove heat loss, for example, outer surfaces of housings for electronic assemblies are provided with cooling fins to reduce the thermal resistance between the surface to be cooled and the environment by increasing the area with the surrounding air. The cooling fins can also lead to turbulences when flowing with an air flow, whereby the heat dissipation is further improved. Usually to be cooled surfaces are provided with parallel web-like cooling fins, since they are easy to manufacture.

However, parallel cooling fins have the disadvantage that a cooling effect depends significantly on the position of the cooling surface with respect to a gravity vector. Since the cooling takes place mainly by convection of the heated air in passive cooling devices, an air flow can form well between the cooling fins, if the cooling fins run parallel to the gravity vector and thereby ensure heat dissipation. If the cooling fins run perpendicular to the gravity vector, the air flow runs over the cooling fins, and substantially no air movement takes place between the cooling fins, so that the surface-enlarging effect of the cooling fins remains virtually ineffective.

Housing components with an applied cooling device are often manufactured in one piece as a cast component. However, such a housing component with an outer surface provided with parallel cooling ribs can lead to an increased correction effort in the casting tool, since the cooling ribs stiffen in their longitudinal direction, the component remains transversely unstable and can distort on cooling.

Disclosure of the invention

This object is achieved by the cooling device according to claim 1 and a housing with such a cooling device according to the independent claim.

Further embodiments are specified in the dependent claims.

• – eine zu kühlende Fläche;
• – mehrere sternförmig auf der zu kühlenden Fläche angeordnete längliche stegartig hervorstehende Kühlrippenstrukturen, die zu einem Zentrumsbereich der zu kühlenden Fläche ausgerichtet sind.

According to a first aspect, there is provided a cooling device for cooling a housing, comprising:

• A surface to be cooled;
• - Several star-shaped arranged on the surface to be cooled elongated web-like protruding fin structures, which are aligned to a center region of the surface to be cooled.

One idea of the above cooling device is to arrange cooling rib structures in a star shape on a surface to be cooled, so that an air flow between adjacent cooling rib structures can always be formed when the surface to be cooled is arranged parallel to the gravity vector. As a result, an improved heat dissipation is independent of a parallel to the gravity vector mounting position possible.

If the surface to be cooled runs perpendicular to the gravity vector, in particular with the cooling fin structures pointing upwards, a chimney effect can form through the arrangement of the cooling fin structures, which causes an air flow between the cooling fin structures to the center of the cooling device and a chimney effect on the center due to the convection of the collected heated air arises. Thus, it is possible to provide a cooling device, with the almost installation position independent improved cooling effect can be achieved.

Furthermore, the star-shaped arrangement of the cooling fin structures in a one-piece design on the surface to be cooled allows stiffening of the surface structure in both surface directions.

Overall, an efficient cooling effect can be achieved by the above cooling device regardless of the orientation of the component with respect to the gravity vector, taking into account a maximum torsional rigidity.

Furthermore, the star-shaped cooling fin structures can not be directly connected and in particular have a predetermined minimum distance of in particular more than 2 mm, preferably more than 3 mm, to each other. Due to the minimum distance between the cooling rib structures, it is achieved that an air flow can always form between the cooling rib structures, which is not obstructed by the wall friction losses or wall flow losses due to narrow ducting. In particular, it is ensured by maintaining the minimum distance between the cooling rib structures that an air flow can form between the cooling rib structures. If the distance is too short, wall flow losses will result As a rule, no air flow is formed.

In particular, a maximum distance of the cooling rib structures on the surface to be cooled may be provided, which in particular corresponds to the sum of a width of the cooling rib structures and the predetermined minimum distance.

It can be provided that first fin structures, which form part of the star-shaped cooling rib structures, are guided in a center region surrounding the center region up to the edge of the center region. Due to the minimum distance between the cooling rib structures, it is achieved that in a central region in which the cooling rib structures converge, no or only a part of the cooling rib structures are guided in and the other cooling rib structures end correspondingly outside the center region.

Furthermore, the center region can correspond to a region which is defined by the mutually facing ends of the first fin structures, wherein the mutually facing ends of the first fin structures have a distance corresponding to a predetermined minimum distance of the fin structures.

The ends of the first fin structures may be connected to a particular annular connecting element arranged in the center region. The connecting element can serve to stiffen the surface to be cooled.

According to one embodiment, the surface to be cooled may be polygonal with the outer ends of a portion of the first fin structures extending to the corners of the surface to be cooled. By arranging the first cooling rib structures from the corners of the surface to be cooled to the center region, a particularly high rigidity of the component can be achieved, on which the surface to be cooled is located.

The fin structures may have a height that is about 1 to 10 times their average width. As a result, ratios of the dimensions of the cooling rib structures are defined, which lead to a particularly effective guidance of the air flow along the cooling rib structures.

It can be provided that the cooling rib structures have a rectangular or tapering towards or away from the surface to be cooled.

According to a further aspect, a housing or housing part may be provided with an outside which is a surface to be cooled and with the above cooling device.

Brief description of the drawings

Embodiments are explained below with reference to the accompanying drawings. Show it:

1 a plan view of a cooling device with a surface to be cooled as an outer side of a housing;

2 a perspective view of the cooling device of 1 ; and

3a and 3b a comparison of a flow pattern for air flow over a cooling device with straight, parallel arranged cooling fin structures and a cooling device with star-shaped cooling fin structures.

Description of embodiments

1 shows a plan view of a cooling device 1 with a particular plane to be cooled surface 2 For example, as an outside of a housing 3 or housing element may be formed. The housing 3 can for example serve to receive an electronic assembly and be made of a good thermal conductivity material, in particular of a metal such as aluminum.

The housing part on which the surface to be cooled 2 may be coupled to the electronic package (not shown) so that the heat developed in the electronic package is transferred to the package with a low thermal resistance. About the cooling device, the resulting heat in the assembly is then dissipated.

The surface to be cooled 2 is with cooling fin structures 4 provided substantially web-like of the surface to be cooled 2 protrude and run straight. Basically, the cooling fin structures increase 4 the interface between the cooling device and the environment and thereby reduce the thermal resistance. In particular, the cooling fin structures 4 perpendicular to the surface to be cooled 2 stand out and have a rectangular to the surface to be cooled towards or away from tapering cross-section. The cooling fin structures 4 are along star-shaped half-lines L on the surface to be cooled 2 arranged. The star-shaped half lines L can be arranged with uniform angles or with variable angles to each other. For optimal guidance of the air flow too ensure, it is appropriate that the height H of the cooling fins is 1 to 10 times, in particular 2 to 5 times their width B. In particular, the heights of the cooling fins along their courses can also vary within the above size ranges.

The cooling device with the surface to be cooled 2 and the cooling fin structures disposed thereon 4 Can be integral with the housing 3 or the housing part, in particular as a casting of a metal, such as aluminum or the like. The star-shaped arrangement of the cooling fin structures 4 allows improved rigidity of the housing, so that the molded housing part is dimensionally stable.

It was found to be between the fin structures 4 can not form an air flow when the distance between the adjacent fin structures 4 is too low. This eliminates too small distance of the cooling fin structures 4 the achieved by this enlargement of the interface in this area. Instead, a corresponding air flow passes over the cooling fin structures 4 time. The low or nonexistent air convection between the finely spaced fin structures 4 causes a significant reduction in heat dissipation.

In particular, in a star-shaped arrangement of the cooling fin structures 4 The cooling fin structures are approaching 4 toward a center region M on each other and adjacent fin structures 4 would be below the minimum distance necessary to achieve an air flow between the cooling fins. It is therefore provided for the center region M that there is no or only part of the cooling fin structures therein 4 extends into it.

In the exemplary embodiment shown, only six of the cooling rib structures extend 4 , as first cooling fin structures 4a , in the middle region M in, while between them in each case three second fin structures 4b are arranged along the star-shaped half-line L, which ends already outside of the central region M. The first cooling fin structures 4a which extend into the central region can end outside a center region Z, in which the star-shaped lines L meet and which can be arranged approximately centrally in the middle region M, and therefore can not be directly connected to one another.

For better stability of the housing 3 However, in the center region Z, a connecting element 5 may be arranged, for example, which is arranged annularly, and lying in the middle region M ends of the first fin structures 4a connect with each other. The connecting element 5 has an annular ridge whose height HS is 1 to 10 times, in particular 2 to 5 times its width BS.

This will increase the stability of the entire case 1 clearly improved. At the same time, the connecting element is impaired 5 not the flow of air between the first fin structures extending into the central region M 4a ,

It was found that due to the velocity boundary layer of air a minimum distance of the fin structures 4 should not be less than 2 mm. For example, a distance D between the fin structures 4 of 3 mm certainly an air flow between the cooling fin structures 4 guarantee. Depending on the width B of the cooling fin structures 4 and the number A of the star-shaped half lines L results in a radius r of the circular center region M of r = A * (B + D) / 2π, where D is the distance of the fin structures 4 equivalent. In particular, there is an improved guidance of the air flow into the interior of the center region, if every third, fourth or every fifth cooling rib structure 4 extends into the center of the center.

Furthermore, it is provided that, depending on the dimensions of the surface to be cooled 2 the outwardly increasing distance between two adjacent fin structures 4 should not be arbitrarily large, since it can not achieve the improved heat dissipation due to the improved thermal resistance R _th = 1 / (α · A) (with α as the heat transfer coefficient and A as the surface), resulting in the provision of the fin structures 4 by increasing the surface yields. Therefore, there is provided there by adding another fin structure 4 to reduce the thermal resistance. Thus, it can be provided, further cooling fin structures 4 to arrange in a star shape as soon as the distance between two cooling fins 2d + b reaches or exceeds.

In particular, the course and orientation of the first fin structures 4a which extend into the central area, depending on the shape of the surface to be cooled 2 be provided. In particular, it is for reasons of rigidity of the housing 3 on which the area to be cooled 2 is, suitably, that the first fin structures 4a from a corner of the surface to be cooled 2 or a corner of the housing 3 in the center region M, in particular in the center region Z, extend. This ensures optimal rigidity.

How to get out 2 can recognize the area to be cooled 2 rounded at the edges. It is advantageous to track the protruding edges of the cooling fin structures of the contour of the surface to be cooled and in particular the height of the fin structures 4 constant over the surface to be cooled.

In the 3a and 3b can be seen in comparison with a surface to be cooled, with rectilinearly parallel cooling fin structures 4 is provided that in star-shaped cooling fin structures 4 , Which are arranged on a transverse to the gravity vector to be cooled surface, different convection currents are formed. While in the former case ( 3a ) results in a convection extending over the entire surface to be cooled, arises in the star-shaped arrangement ( 3b ) a chimney effect, which forms an air flow parallel to the cooling surface outside the center region and in the middle region to a strong vertical flow in the direction opposite to the gravity vector. This will increase the flow rate in the spaces between the fin structures 4 increased and achieved an improved cooling effect.

Claims (11)

Cooling device for cooling a housing, comprising: - a surface to be cooled ( 2 ); - several star-shaped on the surface to be cooled ( 2 ) arranged elongate web-like protruding fin structures ( 4 . 4a . 4b ) leading to a center region (Z) of the surface to be cooled (Z) 2 ) are aligned. Cooling device according to claim 1, wherein the star-shaped cooling rib structures ( 4 . 4a . 4b ) are not directly connected to each other and in particular have a predetermined minimum distance of in particular more than 2 mm, preferably more than 3 mm, to each other. Cooling device according to claim 1, wherein the star-shaped cooling rib structures ( 4 . 4a . 4b ) are not directly connected to each other and in particular have a predetermined minimum distance from each other, which corresponds to a factor between 1 to 5, in particular a factor between 2 and 3 of its width. Cooling device according to claim 2 or 3, wherein a maximum distance of the cooling rib structures ( 4 . 4a . 4b ) on the surface to be cooled ( 2 ), in particular the sum of a width of the cooling rib structures ( 4 . 4a . 4b ) and the predetermined minimum distance. Cooling device according to one of claims 1 to 4, wherein first cooling rib structures ( 4a ), which form part of the star-shaped cooling rib structures ( 4 . 4a . 4b ), in a center region (Z) surrounding the center region (M) are guided to the edge of the center region (Z). Cooling device according to claim 5, wherein the center region (Z) corresponds to a region which is defined by the mutually facing ends of the first cooling rib structures (FIG. 4 . 4a . 4b ), wherein the mutually facing ends of the first fin structures ( 4a ) have a distance which corresponds to a predetermined minimum distance of the cooling rib structures ( 4 . 4a . 4b ) corresponds. Cooling device according to claim 5 or 6, wherein the ends of the first cooling rib structures ( 4a ) with a in the center region (Z) arranged in particular annular connecting element ( 5 ) are connected. Cooling device according to one of claims 5 to 7, wherein the surface to be cooled ( 2 ) is polygonal, the outer ends of at least a portion of the first fin structures ( 4a ) to one of the corners of the surface to be cooled ( 2 ). Cooling device according to one of claims 1 to 8, wherein the cooling rib structures ( 4 . 4a . 4b ) have a height which corresponds approximately to 1 to 10 times their average width (B). Cooling device according to one of claims 1 to 9, wherein the cooling rib structures ( 4 . 4a . 4b ) a rectangular or towards or away from the surface to be cooled ( 2 ) have a tapered cross-section. Casing ( 3 ) or housing part with an outside which has a surface to be cooled ( 2 ), and with a cooling device according to one of claims 1 to 10.

Images