Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2001-10-31
2003-04-08
Bennett, Henry (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S185000, C361S695000, C361S697000, C174S016300
Reexamination Certificate
active
06543522
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an arrayed fin cooling system for removing heat from a component. More specifically, the present invention relates to an arrayed fin cooling system that includes a plurality of discrete cooling fins arranged in a radial array and with each of the cooling fins serving as a heat sink, so that collectively, the cooling fins efficiently remove heat from the component.
BACKGROUND OF THE INVENTION
It is well known in the electronics art to place a heat sink in contact with an electronic device so that waste heat generated by operation of the electronic device is thermally transferred into the heat sink thereby cooling the electronic device. With the advent of high clock speed electronic devices such as microprocessors (&mgr;P), digital signal processors (DSP), and application specific integrated circuits (ASIC), the amount of waste heat generated by those devices and the operating temperature of those devices are directly proportional to clock speed. Therefore, higher clock speeds result in increased waste heat generation which in turn increases the operating temperature of the device. However, efficient operation of the device requires that waste heat be effectively removed.
Heat sink devices came into common use as a preferred means for dissipating waste heat from electronic devices such as the types described above. In a typical application, a component to be cooled is carried by a connector that is mounted on a PC board. Efficient dissipation of heat from the component by the heat sink depends to a large extent on the thermal contact between the heat sink and the component and the contact pressure between the heat sink and the component. Ideally, an attachment device, such as a clip or the like, positions the heat sink so that the a surface of the heat sink is in contact with the component and so that the contact pressure between the heat sink and component acts along a load axis that is centered on the component. Additionally, a fan is usually used to generate an air flow through the heat sink so that waste heat in the heat sink is thermally transferred from the heat sink to the air flow.
Heat sinks that are currently available on the market are manufactured using prior machining processes that include extrusion, impact forging, and vacuum brazing. A few heat sinks are produced using a die casting process. However, it is difficult to produce a high performance heat sink using the die casting process. The objective of all of those prior machining processes is to produce a heat sink having a plurality of fins that are connected with a heat mass and that provide an air flow path over the fins that will remove waste heat from the fins and the heat mass.
All of the aforementioned prior machining processes have their own limitations on a Length to Breadth ratio (L/B) on a fin gap between adjacent fins on the heat sink. Generally, in extruded heat sinks, efficiency depends on the number of fins that can formed in a given area. To increase that area within a given volume, the L/B ratio must be increased. Typically, the area is increased by decreasing the fin gap between adjacent fins (i.e. B is reduced) and by increasing a height of the fins (i.e. L is increased). However, the extrusion process has limitations on the L/B ratio. That L/B ratio limitation paved a path for heat sinks to grow in size in a X-direction and a Y-direction in order to cater to the high performance cooling needs of the above mentioned high clock speed electronic devices.
One disadvantage to the prior machining processes is that a slit width that is used to form an air gap between adjacent fins is parallel due to slitting wheels that are used to machine the slits. As a result, a cross-sectional area of the fin is reduced in a direction towards a center of the heat mass of the heat sink.
A second and related disadvantage to the prior machining processes is that a fin depth is reduced with a subsequent reduction in a surface area of the fin that is available to transfer the waste heat to the air flow over the fin.
A third disadvantage is that the number of fins that can be cut into the heat mass is reduced. Therefore, there are fewer fins available to transfer the waste heat from the fins to the air flow.
Finally, the prior machining processes can be complicated and can require several machining steps that increase the cost of producing the heat sink. There are many applications that use high clock speed electronic devices that also require a low cost heat sink.
Consequently, there is a need for a heat sink that can be manufactured at a low cost and without complex and time consuming machining processes. There is also a need for a heat sink that can accommodate a large number of fins having a large surface area. Additionally, there exists a need for a heat sink with deep fins that have a large cross-sectional area at the heat mass.
SUMMARY OF THE INVENTION
The arrayed fin cooling system of the present invention solves the aforementioned problems. The problems associated with manufacturing costs and complexity are solved by using a plurality of discrete cooling fins to form an arrayed fin cooling system. The discrete cooling fins can be manufactured at a low cost using a process such as stamping, for example.
The problems associated with fin surface area and the number of fins are solved by the discrete cooling fins because each cooling fin acts as a discrete heat sink and the area of the fin can be made as large as is necessary for the intended application. The number of cooling fins can be increased by decreasing a thickness of each cooling fin.
Because the cooling fins define a heat mass of the arrayed fin cooling system, a depth of the cooling fins is not limited by the machining processes used to form the cooling fins. Therefore, the problems associated with the fins having a larger cross-section area at the heat mass are solved by the using the discrete cooling fins of the present invention.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.
REFERENCES:
patent: 5661638 (1997-08-01), Mira
patent: 6134108 (2000-10-01), Patel et al.
patent: 6401808 (2002-06-01), Hanzlik et al.
patent: 6404634 (2002-06-01), Mann
patent: 6452803 (2002-09-01), Liu
patent: 6466444 (2002-10-01), Cheung
Bennett Henry
Denny III Trueman H.
Duong Tho V
Hewlett--Packard Development Company, L.P.
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