Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2003-01-24
2004-08-24
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S080300, C165S121000, C165S185000, C165S908000, C257S722000, C361S695000, C361S703000, C454S186000
Reexamination Certificate
active
06781834
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a cooling device including an air impingement chamber. More specifically, the present invention relates to a cooling device including an air impingement chamber that disrupts an air flow through the cooling device so that air turbulence is increased with a resulting increase in heat transfer from the cooling device to the air flow.
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 electronic devices and the operating temperature of those electronic 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 electronic device. However, efficient operation of the electronic device requires that waste heat be continuously and 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. A heat sink is mounted on the component by attaching the heat sink to the connector using a clip or fasteners, for example. Attentively, the heat sink is mounted to a PC board that carries the electronic device and fasteners or the like are used to connect the heat sink to the PC board via holes that are drilled in the PC board.
Typically, a heat sink used in conjunction with a modem high clock speed electronic device will use an electrical fan connected with the heat sink and operative to supply an air flow over a plurality of cooling finstvanes of the heat sink. The cooling fins/vanes increase a surface area of the heat sink and maximize heat transfer from the heat sink to ambient air that surrounds the heat sink. The fan causes air to circulate over and around the cooling fins thereby transferring heat from the cooling fins into the ambient air.
As mentioned previously, with continuing increases in clock speed, the amount of waste heat generated by electronic devices has also increased. Accordingly, to adequately cool those electronic devices, larger heat sinks and/or larger fans are required. Increasing the size of the heat sink results in a greater thermal mass and a greater surface area from which the heat can be dissipated. Increases in fan size provide for more air flow through the cooling fins.
There are disadvantages to increased fan and heat sink size. First, if the size of the heat sink is increased in a vertical direction (i.e. in a direction transverse to the PC board), then the heat sink will be taller and may not fit within a vertical space in the system that carries the heat sink, such as the chassis of a desktop computer, for example.
Second, if the PC board has a vertical orientation, then a heavy and tall heat sink can mechanically stress the PC board and/or the electronic device resulting in a device or PC board failure.
Third, a tall heat sink will require additional vertical clearance between the heat sink and a chassis the heat sink is contained in to allow for adequate air flow into or out of the fan.
Finally, increases in fan size to increase cooling capacity often result in increased noise generation by the fan. In many applications such as the desktop computer or a portable computer, it is highly desirable to minimize noise generation. Moreover, in portable applications that depend on a battery to supply power, the increased power drain of a larger fan is not an acceptable solution for removing waste heat.
Another disadvantage of prior cooling devices is that the air flow over the fins/vanes can be non-turbulent. Although a non-turbulent air flow can result in reduced air flow noise, it can also create a thermal boundary layer that reduces heat transfer from the fins/vanes into the air flow thereby reducing a heat transfer rate from the cooling device into the ambient air.
Consequently, there exists a need for a cooling device that takes advantage of increased air turbulence in order to disrupt a thermal boundary layer and to increase a heat transfer rate from the cooling device to an air flow through the cooling device. There is also a need for a cooling device in which the heat transfer rate can be increased without having to increase a surface area of the cooling device, a mass of the cooling device, or a rate of air flow through the cooling device.
SUMMARY OF THE INVENTION
Broadly, the present invention is embodied in a cooling device with an air impingement chamber for dissipating heat from a component. Typically, the component is an electronic component or an electronic device; however, the cooling device of the present invention can be used in conjunction with any heat producing device and is not limited to use with electronic devices or components.
Broadly, the present invention is embodied in a cooling device for dissipating heat from a component. The component can be any component requiring the removal of heat. The cooling device includes a heat mass with a top surface and a mounting surface adapted to thermally connect the heat mass with the component to be cooled. A plurality of fins are connected with the top surface of the heat mass and are substantially aligned with a vertical axis of the heat mass. Each fin includes opposed side surfaces, a top edge, a leading edge, and a trailing edge and the fins are spaced apart from one another to define a plurality of slots between adjacent fins. The slots are substantially aligned with a longitudinal axis of the heat mass.
The cooling device also includes an air shower with an air inlet that extends into the air shower to define an air impingement chamber. The air shower includes an injector face and a plurality of disrupter orifices extending from the air impingement chamber to the injector face. The injector face is positioned adjacent to the top edges of the fins so that disrupter orifices are positioned over the slots.
A second air flow enters the air impingement chamber through the air inlet and exits the air impingement chamber through the disrupter orifices. The second air flow enters the slots between the fins and impinges on a first air flow flowing through the slots. The second air flow induces turbulence in the first air flow and that turbulence is operative to disrupt a thermal boundary layer in the first air flow thereby increasing a rate of heat transfer from the fins and the heat mass to the first air flow.
As a result, heat is more efficiently removed from the heat mass and the fins without having to resort to increases in the size of the heat mass, a surface area of the fins, the size of the fan, or the flow rate of the first air flow.
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: 4851965 (1989-07-01), Gabuzda et al.
patent: 5195576 (1993-03-01), Hatada et al.
patent: 5563768 (1996-10-01), Perdue
patent: 5810072 (1998-09-01), Rees et al.
patent: 6000908 (1999-12-01), Bunker
patent: 6650838 (2003-11-01), Tanaka et al.
Nair Manu Kumar Velayudhan
Ravikumar Frederick Rajendran
Denny III Trueman H.
Hewlett--Packard Development Company, L.P.
Thompson Gregory
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