U.S. patent number 3,592,260 [Application Number 04/882,509] was granted by the patent office on 1971-07-13 for heat exchanger with inner guide strip.
This patent grant is currently assigned to Espey Mfg. & Electronics Corporation. Invention is credited to Harvey L. Berger.
United States Patent |
3,592,260 |
Berger |
July 13, 1971 |
HEAT EXCHANGER WITH INNER GUIDE STRIP
Abstract
In a rectangular heat exchanger for electronic equipment wherein
part of said equipment is placed on one end wall of the heat
exchanger while air is brought into the heat exchanger by fan means
located towards the other end wall and said air is channeled in the
heat exchanger by a plurality of guide vanes extending generally
radially outwards from a zone surrounding said fan means, the
improvement therein wherein said heat exchanger includes an
elongated resilient strip which has the inner end resting on a
bottom wall of the heat exchanger, with the center portion thereof
going around said fan means zone and the outer end extends across
the mouths of flow channels which it is desired to cut off thereby
increasing the air flow to the other channels to enhance the
cooling to the electronic components.
Inventors: |
Berger; Harvey L. (Saratoga
Springs, NY) |
Assignee: |
Espey Mfg. & Electronics
Corporation (Saratoga Springs, NY)
|
Family
ID: |
25380748 |
Appl.
No.: |
04/882,509 |
Filed: |
December 5, 1969 |
Current U.S.
Class: |
165/121; 165/185;
174/16.1; 165/DIG.303; 361/696; 257/E23.099 |
Current CPC
Class: |
F28F
13/06 (20130101); H01L 23/467 (20130101); Y10S
165/303 (20130101); H01L 2924/0002 (20130101); H01L
2924/0002 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
F28F
13/06 (20060101); H01L 23/467 (20060101); H01L
23/34 (20060101); F28F 13/00 (20060101); F28f
013/00 () |
Field of
Search: |
;165/121,2,184--186
;317/100,234.1 ;174/15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matteson; Frederick L.
Assistant Examiner: Streule; Theophil W.
Claims
What I claim is:
1. In a rectangular heat exchanger for electronic equipment wherein
part of said equipment is placed on one end wall of the heat
exchanger while air is brought into the heat exchanger by fan means
located towards the other end wall and said air is channeled in the
heat exchanger by a plurality of guide vanes extending generally
radially outwards from a zone surrounding said fan means, the
improvement therein wherein said heat exchanger includes an
elongated resilient spiral strip which has the inner end resting on
a bottom wall of the heat exchanger, with the center portion
thereof going around said fan means zone and the outer end extends
across the mouths of flow channels which it is desired to cut off
thereby increasing the airflow to the other channels to enhance the
cooling to the electronic components.
2. In a heat exchanger as claimed in claim 1, including a lower
outlet in said zone to allow water to drip therethrough, a tab in
the center portion of said strip designed to fit in said
outlet.
3. In a heat exchanger as claimed in claim 2, said strip outer end
having a three-pronged grip to engage one of said guide vanes.
4. In a heat exchanger as claimed in claim 3, said strip inner end
having a hairpin bend to increase the resilient effect.
Description
BACKGROUND OF THE INVENTION
The present invention relates to the problem of poor air
circulation within an enclosure used for the purpose of cooling a
piece of electronic equipment, also to the attenuation of the noise
generated by the rush of air past an obstruction in the flow path.
More particularly the present invention relates to the cooling off
of transistors by the use of an air-cooled heat sink where the
cooling air is properly channeled.
Heretofore, transistors were mounted on a metal plate, e.g., of
aluminum and cooling air was fed to the back of the plate. This
system was not only inefficient but also resulted in noise caused
by the air flow.
SUMMARY OF THE INVENTION
Generally speaking, the present invention contemplates an
improvement in a rectangular heat exchanger for electronic
equipment wherein part of said equipment is placed on one end wall
of the heat exchanger while air is brought into the heat exchanger
by fan means located towards the other end wall and said air is
channeled in the heat exchanger by a plurality of guide vanes
extending generally radially outwards from a zone surrounding said
fan means. The improvement contemplated includes an elongated
resilient strip which has the inner end resting on a bottom wall of
the heat exchanger, with the center portion thereof going around
said fan means zone, and the outer end extends across the mouths of
flow channels which it is desired to cut off, thereby increasing
the airflow to the other channels to enhance the cooling to the
electronic components.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention as well as other objects and advantages thereof will
become more apparent from the following detailed description when
taken together with the accompanying drawing, in which:
FIG. 1 is a perspective side view of a heat sink herein
contemplated;
FIG. 2 shows the heat sink of FIG. 1, but with the cover plate
thereon;
FIG. 3A is a side view of the heat sink shown in FIG. 1, but with
an impeller also shown and showing the airflow;
FIG. 3B depicts the flow of air in the arrangement of FIG. 3A, but
with proper guidance as provided by the arrangement contemplated
herein;
FIG. 4A presents a side view of an insert tab contemplated herein;
and,
FIG. 4B shows the outer end of the insert tab of FIG. 4A.
DETAILED DESCRIPTION
The cooling enclosure or heat sink consists of a rectangular
aluminum plate 13 of which one surface 14 is used to mount various
heat producing electronic components. The other surface 19 of the
heat sink is intricately channelled by a series of aluminum struts
21 protruding perpendicular to the plate. The channels formed by
these struts 21 serve the dual purpose of directing the flow of air
produced by a squirrel cage type centrifugal impeller 23 mounted on
the heat sink plate and also providing surface area through which
heat exchange can occur.
For convenience, these aluminum struts have been labeled 1 to 12
starting from the furthest back.
Also included as part of the heat sink is a plate 15 on which are
mounted various heat producing electronic components, e.g.,
transistors 17, located on the end wall of the unit perpendicular
to the first-mentioned heat sink plate 13.
When in operation the channels are enclosed by a cover plate 25,
which forms the fourth wall of the enclosure . This plate has an
opening 27 for air intake at the impeller 23 and for air exhaust 29
at the termination of the channels. The cover plate 25 is shown
superimposed over the heat sink in FIG. 2. The air from the
impeller is also used to cool an area of the equipment not directly
mounted on the heat sink. The air is routed by the central channels
and a flange 31 on the cover plate to the side of the unit where
there are mounted six switching transistors 17 on a plate. This is
shown in FIG. 3. The air passes over these transistors and is then
exhausted through a cutout in the sidewall plate of the unit.
There are two areas of the equipment where the airflow should be
maximized. One is the point of greatest heat dissipation located in
the region of channels 4, 5, 6 and 7 on the heat sink. The other is
the plate containing the six transistors 17. These transistors must
usually be adequately cooled, for example if they are the germanium
type and, therefore, subject to thermal runaway without proper heat
removal. Heretofore, both of these critical areas were inadequately
cooled because of a lack of sufficient airflow. Failure of units in
operation occurred particularly because of the overheating of
germanium transistors. The major fraction of the air (approximately
80 percent) would be directed into channels 1 and 2 on the drawing
of FIG. 1. There are no sources of heat in this region that call
for such a large portion of the airflow being directed there. In
FIG. 4a relative magnitudes of the volume of air directed into
various channels of the heat sink are indicated by the thickness of
the arrows on each path.
In order to redistribute the air leaving the impeller there is
inserted a thin-shaped spiral strip 33 with an inner hairpin bend
of either a metal, plastic or other flexible material into certain
channels of the heat sink. The form of the strip is shown in FIG. 5
and its position of insertion in the heat sink in FIG. 6. The strip
is formed oversized with respect to its dimensions in the heat sink
so that it must be compressed upon insertion to achieve the proper
shape. This is clearly shown in FIG. 6. The springiness of the
strip then acts to hold it in place against the walls. The strip is
to be made wide enough so that one edge, the bottom-edge, rests on
the heat sink plate and the other edge, the top edge, extends so
that it terminates at the same height as do the aluminum struts.
The insert strip thereby effectively behaves as if it were a strut
and acts to channel the air. The insert strip top end 35 begins at
the termination of the aluminum strut which separates channels 3
and 4 the insert strip extends across the inlet mouths of the
channels labeled 1, 2 and 3, then continues as a spiral in contact
with the wall of the impeller scroll, goes completely around the
scroll and past the original cutoff point of the scroll while still
part of the spiral. A sharp hairpin bend 37 forming a new scroll
cutoff point is made and the strip end 39 is then terminated
against the channel wall 41 as shown in FIG. 6.
A locating tab 43 is provided on the top edge of the spiral portion
of the strip which fits into the water drain hole. A three pronged
tab 45 is provided to join the strip end to the aluminum strut
separating channels 3 and 4. The insert is snugly held against the
scroll and other areas of contact with the heat sink by means of
the restoring force of the springy material. Since the aluminum
heat sink is generally a casting, there is an allowable draft of
1.degree. on the walls perpendicular to the major plane of the heat
sink. To compensate for this a 1.degree. taper is incorporated into
the insert strip on the side in contact with the casting walls.
Additionally there is a fillet at the junction of the perpendicular
walls and the major plane of the heat sink. Where the strip bottom
edge must rest on this fillet (e.g. at the scroll) suitable
reduction of the total strip width must be made.
The portion of the insert strip 33 extending across the inlets of
channels 1, 2 and 3 acts to prevent air form entering these
channels, thereby increasing the airflow in channels 4 through 12
and also increasing the flow to the switching transistor plate on
the side of the equipment . The relative magnitude of the volume of
air directed into various areas of the heat sink are shown in FIG.
4b for a unit utilizing the insert strip. In particular, the
airflow to channels 4, 5 and 6 and to the switching transistor
plate is substantially improved relative to the original equipment
with a resulting reduction in the thermal loading in these critical
areas.
The portion of the strip forming the cutoff is designed to
efficiently develop a pressure head across the impeller. The cutoff
on equipment without the strip is quite shallow allowing
recirculation of air around the impeller and also an excessive
noise level. The cutoff in the present invention eliminates
recirculation and reduces air noise. To this end it is necessary
that the arm of the cutoff returning to the channel wall which
forms the termination of the strip be at such an angle that its
major plane, if extended to the impeller wheel, would intersect the
wheel in a tangent at its periphery. This arrangement optimizes the
airflow through the equipment.
The portion of the insert strip within the scroll serves to connect
the two functional ends of the strip.
* * * * *