Device for generating a cooling air flow in a preferential flow direction for cooling electrical components

Abstract

The device for generating a cooling air flow in a preferential flow direction for cooling electrical components, particularly LEDs, comprises a first and a second channel wall (34,36) having mutually confronting inner sides, and an oscillation drive means (42) for generating an oscillating movement of at least a partial region (38) of at least one of said channel walls (34,36) in the direction toward the other channel wall and away therefrom. The inner side of at least one of said two channel walls (34,36) has a surface structure (30) designed for anisotropic flow, which has a smaller flow resistance coefficient in the preferential flow direction (28) than in a direction extending at an angle to the preferential flow direction (28) and particularly in a direction extending opposite to the preferential flow direction (28).

Description

RELATED CROSS-REFERENCING[0001]The present invention claims the priority of European Patent Application No. 10 174 853.1 filed on Sep. 1, 2010, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a device for generating a cooling air flow in a preferential flow direction for cooling electrical components, particularly electro-optical components such as e.g. LEDs. The present invention particularly relates to the integration of a device of the above type into a cooling body for cooling electrical components, particularly electro-optical components such as e.g. LEDs.[0004]2. Description of the Prior Art[0005]On the sector of land and air vehicles, efforts have been under way for many years to install LEDs as a replacement of conventional illuminants of the type with filaments or of the gas discharge type. This trend is favored by the recent introduction of high-performance LEDs on ...

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Benefits of technology

[0017]Thus, according to the arrangement proposed by the invention, the air movement oscillating orthogonally to the extension of the channel walls is deflected into an air movement between the two channel walls, said air movement between the two channel walls streaming at different rates in the most different directions parallel to the channel walls and between the latter while, however, due to the anisotropic surface structure, a net or preferential flow direction is obtained. When applying this concept to the cooling plate elements of a cooling body, the device according to the invention can enhance the natural convection in that the cooling plate elements are vertically oriented and the anisotropic surface structure is oriented in such a manner that the preferential flow direction is pointing upward.

[0018]An essential advantage of the device of the invention resides in its reliable cooling effect, while the need for moving component parts, such as e.g. inlet and / or outlet valves operating in opposite senses to each other, is obviated (except for said oscillating partial region of at least one of the channel walls and respectively of an element arranged therebetween). Particularly, no active cooling devices such as e.g. ventilators are required. In aircraft industry, such active cooling measures are presently not admissible because it is feared that the cooling would be considerably impaired in case of a fallout of the active cooling devices such as e.g. ventilators and the like. Apart from the above advantage, the device of the invention and the cooling method of the invention will guarantee their functionality even under extreme ambient conditions. The influence of such ambient conditions or extreme external influences is to be expected on the landing gear of aircraft where the device would be exposed to aggressive media, dirt, flying stones or gravel, icing and vibration. A further advantage of the device of the invention is to be seen in that no complex electronic control process is required and that the oscillation drive unit can be fed directly by the vehicle or aircraft power supply system at different frequencies. The cooling concept provided by the invention is inexpensive and is easily put into practice under the constructional aspect while working with utmost reliability.

[0019]At lower temperatures, the stiffness of the channel wall(s) will increase in those regions where said oscillating partial regions are located. Thereby, the effectiveness of the air movement is reduced, which, however, is not critical because lower temperatures will also require less cooling performance. At higher temperatures, by contrast, the flexibility of the oscillating partial regions of the channel wall(s) will increase, namely exactly when a maximum cooling performance is required.

[0020]A further advantage of the device of the invention is to be seen in that the anisotropic surface structure results in an enlargement of the surface area of the channel wall(s). This is advantageous particularly if the anisotropic surface structure is provided on an element of the cooling body which is dissipating heat to the ambience.

[0021]Apart from the above effects, a further considerable cooling effect is obtained by the feature that, by the (rectangular) deflection of the air flow in the area of the oscillating partial region of at least one of the channel walls and respectively of the element optionally arranged therebetween, the “aerodynamic boundary layer” on the channel wall and respectively on the oscillating partial region is substantially thinner. Herein, an “aerodynamic boundary layer” is to be understood as a nearly immobile air layer arranged directly on the surface of the channel wall and respectively the partial region. Since the movement of air in this region is normally very slight, there is thus only a limited heat exchange between the respective component part and the ambience. Thus, by reduction of the thickness of this effective boundary layer, the heat exchange is improved. By “breaking up” this boundary layer, as achieved by the functionality of the inventive device, the air flowing through the channels can become considerably warmer and thus can dissipate considerably more energy than would be the case in a purely “parallel” flow through the channels.

Problems solved by technology

Further, there exist illumination applications wherein the light is switched on only for a short time, while, however, due to the power density and the available (cooling) surface, there is a risk of inadmissible overheating of the illuminant or lamp in the course of the typical operating period.

Also such cooling bodies, however, cannot prevent the risk of overheating of the LED illuminants.

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