Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-04-27
2001-10-16
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S690000, C361S694000, C361S695000, C257S722000, C174S016100, C174S016300, C165S080300
Reexamination Certificate
active
06304445
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to cooling of electronic components in electronic devices. More particularly, the present invention relates to the removable attachment of a fan to a heat sink of an electronic device.
BACKGROUND OF THE INVENTION
As the art moves towards higher power integrated circuits and components, hereinafter referred to as heat emitting components, heat transfer from the heat emitting components becomes increasingly difficult and more important. One conventional technique used to remove heat from a heat emitting component was to employ a finned heat sink which was placed in thermal contact with the heat emitting component. In this manner, heat generated by the heat emitting component was conducted to the heat sink and then dissipated to the ambient environment.
FIG. 1
is a side plan view of a heat sink structure
10
in accordance with the prior art. Heat sink structure
10
included a finned heat sink
12
in thermal contact with a heat emitting component
14
. During use, heat emitting component
14
generated heat. This heat was conducted to heat sink
12
, which dissipated this heat to the ambient environment.
Heat sink
12
included a base section
16
and a plurality of fins
18
extending upwards from base section
16
. To enhance heat dissipation, a fan
20
was used to draw air between fins
18
. Fan
20
included a motor
22
and a propeller
24
. Fan
20
was mounted to a top T of heat sink
12
such that a longitudinal axis
20
L of fan
20
was perpendicular to base section
16
. During use, motor
22
spun propeller
24
drawing air between fins
18
as indicated by arrows
25
.
As the art moved towards smaller and lighter weight electronic devices, the spacing between fan
20
and a cabinet
26
was reduced. Generally, cabinet
26
was the housing of the electronic device, e.g., a computer system, which protected the internal components including heat sink structure
10
of the electronic device. Disadvantageously, cabinet
26
impeded airflow through fan
20
, which, in turn, restricted airflow between fins
18
of heat sink
12
. More particularly, when the spacing between fan
20
and cabinet
26
was small, airflow between fins
18
of heat sink
12
was severely restricted.
To further enhanced heat transfer from heat emitting component
14
and to allow mounting of heat sink
12
, the area of heat sink
12
was made substantially greater than the area of heat emitting component
14
. More particularly, heat emitting component
14
contacted a central region
30
of base section
16
of heat sink
12
. During use, heat was conducted from heat emitting component
14
to central region
30
, which was the hottest region of heat sink
12
(hereinafter hottest region
30
).
Fan
20
was centrally mounted to heat sink
12
such that motor
22
was aligned with hottest region
30
. Of importance, a dead spot
28
of diminished or no airflow existed directly below motor
22
. Disadvantageously, hottest region
30
, i.e., the hottest region of heat sink
12
, was in contact with dead spot
28
. As a result, there was ineffective heat transfer from hottest region
30
which significantly diminished the ability of heat sink
12
to dissipate heat from heat emitting component
14
.
To prevent failure of heat emitting component
14
, it was important that heat emitting component
14
remained below the maximum allowable operating temperature. When the spacing between cabinet
26
and fan
20
was small, a more powerful fan
20
was used to ensure adequate cooling of heat emitting component
14
. However, using a more powerful fan
20
increased noise, which was detrimental to the performance of the electronic device, and increased power consumption, which increased the overall operating cost of the electronic device. Further, to avoid excess power consumption and to avoid exceeding noise level limits, the size of fan
20
was severely restricted.
SUMMARY OF THE INVENTION
In accordance with the present invention, a heat sink structure having a fan mounted horizontally to a heat sink is presented. By mounting the fan horizontally, the fan forces air to flow horizontally along the length of fins of the heat sink. Since the air flows horizontally, the heat sink structure is well suited for use when the spacing between a cabinet and the heat sink is relatively small.
Further, since the fan is mounted horizontally, space between the cabinet and the heat sink does not have to be allocated to accommodate a vertically mounted fan as in the prior art. Advantageously, this space, which would otherwise be allocated for the vertically mounted fan, is used for other purposes. For example, the fins of the heat sink are made larger thus increasing the surface area, and hence heat transfer efficiency, of the heat sink.
In addition, since the air flows horizontal along the entire length of the fins, the airflow directly contacts the region of the heat sink which is in direct contact with the heat emitting component. By providing airflow to the hottest region of the heat sink, i.e., the region in contact with the heat emitting component, the heat transfer efficiency of the heat sink is maximized.
Recall that in the prior art, the motor of the vertically mounted fan was directly aligned with the hottest region of the heat sink. Disadvantageously, a dead spot, i.e., a region of diminished or no airflow, existed directly below the motor, and this dead spot was in direct contact with the hottest region of the heat sink. As a result, there was ineffective heat transfer from the hottest region of the heat sink. By mounting the fan horizontally in accordance with the present invention, the dead spot of the prior art is eliminated.
In one embodiment, a heat sink structure includes a heat sink having a base section having a first surface and a fan mounted to the heat sink, a longitudinal axis of the fan being parallel to the first surface.
In another embodiment, a heat sink structure includes a heat sink and a fan mounting bracket. The heat sink includes a base section having a first surface and a second surface. A first fin and a second fin extend from the second surface of the base section.
The fan mounting bracket includes a faceplate, a first side extending from the faceplate, and a second side extending from the faceplate. The first side and the second side of the fan mounting bracket are fastened to the first fin and the second fin, respectively.
Also in accordance with the present invention, a method includes mounting a fan to a faceplate of a fan mounting bracket, the fan mounting bracket having a first side and a second side extending from the faceplate. The fan mounting bracket is mounted to a heat sink having a first fin and a second fin. The fan mounting bracket is mounted by fastening the first side of the fan mounting bracket to the first fin and the second side of the fan mounting bracket to the second fin. A first surface of a base section of the heat sink is thermally connected to a heat emitting component such that a longitudinal axis of the fan is parallel to the first surface.
These and other features and advantages of the present invention will be more readily apparent from the detailed description set forth below taken in conjunction with the accompanying drawings.
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patent: 5748446 (
Chervinsky Boris L.
Gunnison McKay & Hodgson, L.L.P.
Hodgson Serge J.
Picard Leo P.
Sun Microsystems Inc.
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