Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-08-27
2003-12-16
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S058000, C310S06000A, C310S064000, C310S268000, C361S697000
Reexamination Certificate
active
06664673
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to cooling devices and, more particularly, to cooling devices for removing heat from electronic devices by a flow of gas, in particular, airflow, said flow being produced by a blower.
BACKGROUND OF THE INVENTION
During normal operation, most electronic devices generate significant amounts of heat. If this heat is not continuously removed, the electronic device may overheat, resulting in damage to the device and/or a reduction in operating performance.
In order to avoid such problems caused by overheating, cooling devices are often used in conjunction with electronic devices.
One such cooling device used in conjunction with electronic devices is a fan assisted heat sink. In such device, a heat sink is formed from a material, such as aluminum, which readily conducts heat. The heat sink is usually placed on top of, and in physical contact with, the electronic device.
One method of increasing the cooling capacity of these heat sinks is by including a plurality of cooling fins that are physically connected to the heat sink. These fins serve to increase the surface area of the heat sink and, thus, maximize the transfer of heat from the heat sink to the ambient air. In this manner, the heat sink draws heat away from the electronic device and transfers the heat to the ambient air.
In order to further enhance the cooling capacity of a heat sink device, an electrically powered blower (an axial fan may serve as the blower) is often mounted within or on top of the heat sink. In operation, the fan forces air to pass over the fins of the heat sink, thus, cooling the fins by enhancing the heat transfer from the fins into the ambient air. As the fins are cooled, heat can be drawn from the electronic device and into the heat sink at a faster rate. The fan typically draws air into the heat sink from the top of the heat sink, passes the air over the fins, and exhausts the air from the heat sink in the vicinity of the bottom (side) of the heat sink. Accordingly, the exhaust air is hotter than the intake air.
There are known devices of this type—see, for example, U.S. Pat. No. 5,867,365 “CPU heat sink assembly” and U.S. Pat. No. 5,661,638 “High performance spiral heat sink”.
The design of the device described in U.S. Pat. No. 5,867,365 comprises an axial fan that produces a flow passing by heat exchanging channels of the heat sink. The majority of inlets to heat exchanging channels are located just opposite the axial fan's impeller with a certain number of said channels being placed radially in relation to fan axle.
U.S. Pat. No. 5,661,638 also involves the application of an axial fan. Specific embodiment of device claimed in said patent involves such placement of heat exchanging channels of the heat sink that they are located centrally-symmetrically about the fan axle. To increase the heat exchange area, the heat exchanging channels are made of spiral-like shape and bent backwards in the direction of blower rotation. In this case the fan is installed in a recess made in the heat sink body.
In the above-mentioned designs, the axial fan produces sufficient air pressure. However, due to the weak airflow in the area adjacent to the fan axle, the conditions for cooling the central part of the heat sink, located underneath the fan, are unfavorable. In this case uniform cooling of the heat sink and electronic device, such as a processor, will not take place. The energy of airflow outgoing from fan impeller, in the axial direction, is expended on deceleration and change in flow direction before entering to the heat exchanging channels. This decreased airflow velocity, passing by the heat exchanging channels doesn't allow good conditions for the heat exchange process.
Centrifugal blowers are rarely used in cooling device designs for the purpose of producing airflow.
Specifically, U.S. Pat. No. 5,838,066 “Miniaturized cooling fan type heat sink for semiconductor device” offers a design employing a centrifugal blower that is installed to the side of the heat sink. In one particular embodiment of this invention the cooling airflow passes by rectilinear heat exchanging channels of the heat sink.
However, placement of the centrifugal blower to the side of the heat sink increases the device size. The location of the centrifugal blower leads to poor coordination between the airflow produced by the blower and the direction of the inlet channels of the heat sink. The loss in airflow energy results in the reduction of airflow speed in the heat exchanging channels and in the decline of heat exchange efficiency. A portion of energy, of the airflow, is also expended in the form of friction against the casing enclosing the blower.
An invention described in the patent of Japan No. 8-195456 entitled “Cooler for electronic apparatus”. This device comprises a centrifugal fan enclosed in the casing and installed above the heat exchanging channels that are made divergent. Another heat sink surface is made so that the possibility of thermal contact with an electronic device is provided for. The inlet of the centrifugal fan faces the heat sink. The fan produces an airflow that passes by heat exchanging channels and then gets drawn into the inlet of the centrifugal fan. Since the centrifugal fan operates by drawing air in to the heat sink, there is an area in the central part of the heat sink that that receives poor airflow movement. This can be seen in the published patent. Therefore, cooling of the heat sink's central part, which is the hottest, is ineffectively performed and results in uneven cooling of the heat sink. To avoid uneven cooling of the heat sink, one has to raise the fan power in order to increase the airflow. In addition, the device is of considerable height because of the centrifugal fans placement above the heat sink, and the electric drives placement above the centrifugal fan.
Increasing the size of the cooling device in a vertical direction (i.e. in a direction transverse to the orientation of the integrated circuit device) is often a problem because of the limited envelope available in many applications, such as in the computer case of a desktop computer and especially for portable electronic devices such us laptop computers. This is an even greater problem because, in most situations, a fairly substantial clearance area is required between the fan opening and the computer case to allow adequate airflow into or out of the fan.
Thus, it would be generally desirable to provide an apparatus, which overcomes these problems associated with fan assisted heat sink devices.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a cooler that achieves more uniform cooling of electronic devices by more effective cooling of the central part of the heat exchange element.
It is another object of the present invention to provide a cooler with an overall reduction in height and in doing so allow for a reduction of the cooling device size.
It is further an object of the present invention to provide an electric motor combined with a heatsink that has a significant reduction in overall height.
In order to achieve these objectives the following described cooler design is needed. According to the present invention, a cooler for electronic devices comprises a heat exchange element, a blower with a radial type impeller, and an electric drive, wherein said heat exchange element comprises heat exchanging means made on one surface of said heat exchange element while its other surface provides thermal contact with a heat-radiating means, said radial type impeller has a shroud with a flat surface from one side, a hub and brackets and a central inlet between the shroud and the hub, said brackets connect the hub with the shroud, said radial type impeller is positioned on the heat exchange element so that the heat exchanging means being surrounded by the radial type impeller and a cooling gas flows to the radial type impeller from the central inlet through the heat exchanging means, said electric drive comprises a magnetic
Askhatov Nil N.
Fedoseyev Lev A.
Fedosov Yuri I.
Lopatinsky Edward L.
Popov Viktor N.
Advanced Rotary Systems LLC
Mullins Burton
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