Patent Application
20090032218
For many devices removing heat is essential in order to keep the device operating effectively. To aid in removal of heat from the device, generally a heat sink is coupled to the device. The heat sink is generally sized according to the amount of heat that the device will be dissipating. In many cases, however, space around the device generating heat is limited. Generally, however, there are other heat sinks or possible heat dissipating materials near the heat sink. Each of these additional heat sinks may not be coupled to a device generating the same amount of heat, and may have extra cooling capacity.
The heat dissipation problems are increased when using heat sinks with electronic devices, because many electronic devices generate a large amount of heat in a relatively small area. For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an apparatus and method for improving the heat dissipation of devices within a chassis.
An apparatus for transferring heat between two surfaces is provided. The apparatus includes a first support plate, a sheet of thermal material adjacent the first support plate, and a second support plate adjacent the sheet of thermal material, wherein the sheet of thermal material is disposed between the first support plate and the second support plate. The apparatus also includes at least one bolt inserted through each of the first support member, the sheet of thermal material, and the second support plate, the at least one bolt configured to be secured into a chassis. Finally, at least one spring is disposed between a shoulder of the at least one bolt and the second support plate.
The present invention can be more easily understood, and further advantages and uses thereof are more readily apparent, when considered in view of the detailed description and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the method and system may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.
Embodiments of the present invention provide for an apparatus for transferring heat between two surfaces. The apparatus includes a sheet of thermal material contacts one heat conducting surface on one side and a second heat conducting surface on the other side. The sheet of thermal material is part of an assembly and is placed between two sheets of metal to support the thermal material. The assembly of the sheet of metal and the thermal material are mounted via a fastener to a desired structure and a spring is inserted between the fastener and the assembly. The assembly can pivot relative to the fastener and the mounting structure to allow the thermal material to make solid contact with each heat conducting surface, yet still allow one or both heat conducting surfaces to be moved out of contact with the thermal material when not transferring heat.
Thermal material 104 acts as the heat transfer medium for heat transfer device 100. Heat transfer occurs through contact between thermal material 104 and each heat conducting member. One heat conducting member (shown in
Thermal material 104 is a material having a high thermal conductivity in the direction of desired propagation of heat. In this embodiment, the heat is transferred from side 112 to side 114, thus thermal material 104 has a high thermal conductivity in the a-direction. The higher the thermal conductivity of thermal material 104, the better propagation of heat between the two heat conducting members. Most materials having the high thermal conductivity desired for this application, however, do not possess the strength to withstand pressing at an angle against another surface.
In one embodiment, thermal material 104 is a material having a high thermal conductivity in the a-b plane. For example, in one embodiment, thermal material 104 is thermal pyrolytic graphite (TPG). TPG is commercially available from Momentive Performance Materials in Wilton, Conn. TPG may be referred to as highly oriented pyrolytic graphite (HOPG), or compression annealed pyrolytic graphite (CAPG), and refers to graphite materials consisting of crystallites of considerable size, the crystallites being highly aligned or oriented with respect to each other and having well ordered carbon layers or a high degree of preferred crystallite orientation, with an in-plane thermal conductivity greater than 1000 W/m-K. In one embodiment, TPG has an in-plane thermal conductivity of approximately 1,500 W/m-K. Here, TPG is oriented such that the in-plane of the TPG is aligned with the a-b plane in
For extra support, thermal material 104 is placed between back support 102 and front support 106. Each of back support 102 and front support 106 is composed of a rigid material capable of withstanding pressure placed by fasteners 108 with minimal bending. The minimal bending helps prevent the brittle thermal material 104 from cracking. In one embodiment, back plate 102 and front plate 106 are aluminum. In an alternative embodiment, back plate 102 is copper and front plate 106 is steel. Both back plate 102 and front plate 106 are generally flat sheets having two apertures 116 for accepting fasteners 108. As shown in
In one embodiment, TPG is formed as described in U.S. Pat. No. 5,863,467 which is hereby incorporated herein by reference. Briefly, to manufacture heat transfer device 100 with TPG, pyrolytic graphite is deposited between back support member 102 and front support member 106. Heat transfer device 100 is then heat treated to form the pyrolytic graphite into a crystal structure. The resulting crystal structure, TPG, has a high in plane conductivity.
Each fastener 108 attaches thermal transfer device 100 to a structure. In this embodiment, each fastener 108 is a bolt which is placed through an aperture 116 of each of front support 102, thermal material 104, and back support 106. In one embodiment, fastener 108 has a shoulder for spring 110 to seat upon. In this embodiment, spring 110 is a helical coil spring placed around fastener 108 and between the shoulder of fastener 108 and front plate 106. In an alternative embodiment, spring 110 contacts shoulder of fastener 108, is only along the side of fastener 108 and not around fastener 108. In other embodiments, spring 110 is mounted between fastener 108 and front plate 106 in other manners as known to those skilled in the art. Additionally, in other embodiments, spring 110 is a metal leaf spring or a compliant rubber bushing. Further, although as shown in
Referring now to
Referring now to
Heat transfer device 100 is mounted in a corner between heat sink 302 and heat sink 304. Fasteners 108 of heat transfer device 100 are secured into a portion of chassis 300. When doors are opened heat transfer device 100 is not in contact with heat sinks 302, 304, and heat transfer device 100 remains secured to chassis 300 with springs 110 in a resting position. When each door of heat sink 302 and 304 is closed, a heat conductive surface of each heat sink 302, 304 comes into contact with the beveled edge of thermal material 104. As each heat sink 302, 304 contacts heat transfer device 100, heat transfer device is allowed to translate along each fastener 108 and pivot slightly. This allows heat transfer device 100 to adjust to each heat sink 302, 304 as they move and contact heat transfer device 100.
Advantageously, heat transfer device 100 enables heat transfer between two heat conducting members without permanent connection to the heat conducting members. One or both heat conducting members to be movable, while still allowing each heat conducting member to transfer heat when in contact with heat transfer device 100. As shown in
Although
In an alternative embodiment, multiple heat transfer devices are used to transfer heat between two surfaces. Multiple heat transfer devices are used, for example, to conform to a non-flat surface. When the surface or surfaces from which heat is transferred between have variations, a different heat transfer device can be used to match the different angled section of the surface. Additionally, the length and width of the heat transfer device, or devices can be changed to conform to the surfaces, the amount of heat transfer, or surrounding devices. Finally, in one embodiment, a strip of conductive pad material is used along each edge of heat transfer device 100 to improve contact with a heat conducting member.
Further, although
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to base any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
