U.S. patent number 3,597,117 [Application Number 04/790,345] was granted by the patent office on 1971-08-03 for fan for narrow environments.
This patent grant is currently assigned to Rotorn Incorporated. Invention is credited to Gunther Zoehfeld.
United States Patent |
3,597,117 |
Zoehfeld |
August 3, 1971 |
FAN FOR NARROW ENVIRONMENTS
Abstract
A centrifugal fan for narrow environments is described wherein a
stator is mounted to a backplate and is surrounded by a cup-shaped
rotor carrying a suitable impeller on its outer periphery to
provide a centrifugal output from an axial input. The resultant
assembly has a small axial length with a high air delivery and can
be substantially enclosed in a housing and mounted in a narrow
space.
Inventors: |
Zoehfeld; Gunther (West Hurley,
NY) |
Assignee: |
Rotorn Incorporated (Woodstock,
NY)
|
Family
ID: |
25150395 |
Appl.
No.: |
04/790,345 |
Filed: |
January 10, 1969 |
Current U.S.
Class: |
417/354; 417/371;
415/206 |
Current CPC
Class: |
F04D
17/16 (20130101); F04D 25/0613 (20130101) |
Current International
Class: |
F04D
25/06 (20060101); F04D 17/16 (20060101); F04D
25/02 (20060101); F04D 17/00 (20060101); F04b
017/00 (); F04b 035/04 (); F04b 039/06 () |
Field of
Search: |
;230/117,117A,259
;415/212,206 ;417/354 ;416/206,188 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Vrablik; John J.
Claims
I claim:
1. A blower assembly for use in narrow environments comprising, a
housing; a stator assembly; a rotor assembly in operative relation
with said stator assembly to form a motor and including an outer
portion concentrically surrounding the stator assembly; and an
impeller carried on the periphery of said outer portion of the
rotor assembly for converting an axial airflow to a radial airflow,
said impeller including a plurality of blades and means for
supporting the blades and guiding an axial input airflow to a
radial output flow, said means being integrally formed with said
blades and including a radially extending support plate coupled to
said rotor assembly adjacent one end thereof, the surface of said
plate facing the other end of said rotor assembly being gradually
curved from its inner periphery near the one end of the rotor
assembly towards its outer edge to guide the axial input airflow to
a radial output flow while permitting cooling airflow near the
rotor outer portion for a substantial axial distance, said support
plate being thickened from its inner periphery toward its outer
edge for a substantial portion of the distance between said inner
periphery and said outer edge to add rigidity to said support
plate, and said plate supporting said blades in cantilever fashion
from said surface, the thickening of the support plate forming a
rearward projecting reinforcing annular section where the plate
joins the rotor assembly to provide means resisting stresses
applied by operation of the impeller to the plate near its joinder
with the rotor assembly, the housing having a central opening for
admitting said axial airflow to the interior of the housing
substantially adjacent to the inner periphery of said impeller, and
an exhaust opening for said radial output flow, and wherein said
motor and impeller are mounted within said housing in an operative
relationship to said openings, the central opening is substantially
concentric with and larger than the rotor assembly and defines a
substantially annular axial flow opening adjacent the outer surface
of the rotor assembly aligned with the gradually curved portion of
the plate to introduce air into the blower assembly toward the
curved plate portion, and said housing includes a rearward section
supporting the stator assembly, rotor assembly and impeller within
the housing and defining an outer planar mounting surface adapted
for cooperation with fastening means for mounting flush against an
exterior planar surface to support the blower assembly thereon.
Description
The trend toward the miniaturization of electronic components has
resulted in the use of electronic packages that are extremely small
and compact. Since these packages are generally enclosed, the heat
generated by these components will cause extremely high
temperatures to develop inside the package thereby distorting their
operating characteristics. Due to the decreased size of the
components, this problem is magnified since more and more of them
are contained in each package and, therefore, more and more heat is
generated. In order to remove this heat, it is desirable to use
fans to exhaust the air inside the packages and carry away the
heat. To be compatible with these packages, the fans must be
extremely small in order to fit into the small environment provided
and to maintain the package weight at a minimum. To be effective in
these packages, they must be capable of a very high air
delivery.
A major problem with the miniaturization of fans has been to
provide a fan with a small axial length that is capable of meeting
the high air delivery requirements of dense electronic packages.
The provision of such a fan would allow for smaller electronic
installations since the space required for fan mountings could be
reduced and since fewer and denser packages could be used.
One solution to the problem of cooling electronic packages has been
the tube axial fan, that is, one that moves air axially of the
motor within an outer shroud or tube, and wherein the blades are
mounted on the periphery of the rotor. While this kind of fan has
the desired short axial length, it has a limited air delivery and
is therefore restricted in its application to relatively low
density packages.
Another solution to this problem has been to use a centrifugal fan,
that is, one that has an axial intake and a radial exhaust. These
fans meet the air delivery requirements of dense electronic
packages, but since the impeller ordinarily is mounted on a shaft
extending axially from the motor, they are relatively long in the
axial direction and may not be usable where space is at a
premium.
In addition, the prior art centrifugal fans are costly, since the
impeller comprises a flat, thin backplate having a central opening
which carries a mounting sleeve which, in use, is secured to the
motor shaft. The blades are secured to the face of the backplate by
some type of adhesive and/or mechanical interlock means. These
impeller assemblies, therefore, consist of a number of separate
parts that require elaborate and expensive manufacturing processes.
These fans also require some type of support spider for the shaft
and impeller at the inlet side thereof and this not only adds to
their cost, but also impedes inlet airflow.
In addition to the problems described above, the prior art
centrifugal fans suffer from short bearing life since the waste
heat generated by the motor is not dissipated. This represents a
costly maintenance problem since replacement of bearings or fans is
a difficult and costly operation and sometimes requires the
dismantling of the entire electronic installation.
This invention overcomes the above mentioned problems and provides
a narrow fan with a high air delivery, comprising a stator assembly
which can be mounted on the backwall of a blower housing which, in
turn, can be mounted to an electronic package. A cup-shaped rotor
assembly is mounted around the stator assembly and carries, on its
outer periphery, an integral impeller that draws air from inside
the associated package, over the motor, and exhausts it radially.
Since the impeller is mounted directly to the rotor, the axial
length of the fan is significantly reduced, waste heat from the
motor is carried away, and inlet airflow is not impeded. The cost
of the fan is reduced since the impeller can be cast as a unitary
member and secured to the rotor or cast integrally therewith.
It should be understood, of course, that a fan according to this
invention is not limited to use in electronic packages, but has
utility wherever high air delivery, size and economy are critical,
for example, in projector lamps, heat sinks, power supplies,
instruments, and hand held heat guns.
For a better understanding of this invention, reference is made to
the following description of an exemplary embodiment, and to the
accompanying drawings in which:
FIG. 1 is a view in cross section of a fan according to this
invention taken generally along the line 1-1 of FIG. 2 and looking
generally in the direction of the arrows;
FIG. 2 is a rear view of a blower housing that can be used to mount
the fan of this invention; and,
FIG. 3 is a front view of the blower housing shown in FIG. 2 with
parts broken away to show the fan blades of this invention.
Referring now to FIG. 1 of the drawings, a fan assembly in
accordance with this invention is shown generally at 10 and
comprises, a rotor 12 carrying a centrifugal impeller 14 and
rotatably carried by a stator 16 to provide a fan assembly. The fan
assembly may be carried by and substantially enclosed in a
snail-shaped housing 18 which may be secured to a suitable support
structure, for example, the housing of an electronic package.
The rotor 12 comprises a cup-shaped member including a flat base
portion 20 supporting the annular laminations 23 and end ring 22.
Projecting axially from the inner face of the base portion 20 and
interiorly of the rotor is a central boss member 26, the purpose of
which will be explained hereinafter.
The impeller 14 comprises a backplate 28 that extends radially from
the outer periphery of the end ring 22 near the free end thereof
and includes a thickened inner portion 29 that adds rigidity to the
joint between the backplate and the flange. In order to guide the
air from an axial to a radial flow, the outer face of the thickened
portion slops as shown at 31. Projecting outwardly, as best seen in
FIG. 1, and downwardly, as best seen in FIG. 3, from the backplate
28, there are a plurality of cantilevered blades 30 for exhausting
the air centrifugally. This provides for the economical manufacture
of the impeller since the blades may be cast integral with the
backplate and this may be carried further by casting the entire
impeller integral with the rotor. If the backplate is not cast
integral with the rotor, it may be secured thereto by any suitable
fastener means.
The stator assembly 16 comprises a laminated core 32 and suitable
windings 33 around the core 32 to produce the revolving magnetic
field when connected to an alternating current source.
A suitable base member carries the stator 16 and comprises a
circular plate portion 34 having a central opening 36 therein and a
lip portion 38 around its outer periphery, the purpose of which
will be more fully explained hereinafter. On its inner face, the
plate 34 contains an annular grooved portion 40 that mates with the
inner face of stator 16. Projecting inwardly from the central
opening 36, there is provided a flange member 42 that cooperates
with the groove 40 to adhesively secure the stator to the
plate.
The rotor 12 is rotatably secured to the stator by a shaft 44 which
is keyed to the bass 26 on the inner face of the base plate 20 and
which is received in a cylindrical bearing 46 carried by the inner
periphery of the stator 12 in any suitable manner, as for example,
by a press fit. Suitable thrust washers 48 and 50 are carried,
respectively, on the shaft between the boss 26 and the bearing and
between a retaining ring 52 and the bearing. The retaining ring 52
snaps over the shaft and prevents longitudinal movement
thereof.
It is to be understood that the above-described fan assembly could
be used by itself or, as previously mentioned, could be placed in a
housing 18. One such housing is herein described and comprises a
cup-shaped member having a rear wall 54 with a central opening 60
therein and a forwardly extending sidewall 55 around its periphery.
Preferably, opening 60 is of a sufficient size to receive the fan
assembly when it is installed in the housing. Extending around the
central opening 60 is a shoulder portion that receives the lip
portion 38 of the plate portion 34. In order to secure the plate
portion to the housing, the rear wall includes a plurality of
depressions 62 that extend to the same depth as the lip 38.
Flat-headed fasteners 64 are then inserted into openings 65 spaced
below the depressions 62 and when the fasteners are tightened they
clamp the plate portion 34 to the housing.
A front wall member is secured to the sidewall 55 to complete the
housing and comprises a plate 69 having a central opening 70
therein which allows for the passage of air. As can best be seen in
FIG. 2 and 3, the housing is of the usual snail shape so as to
provide a centrifugal exhaust 66.
The backwall 54 of the housing carries a plurality of mounting lugs
56 projecting radially beyond the edge thereof and extending
throughout its width. These lugs have suitable apertures
therethrough for the receipt of fasteners for attachment to an
electronic package.
It should be clear from the preceding description that a fan in
accordance with this invention can be mounted in extremely narrow
environments, will provide a high air delivery, and will be more
economical to make and maintain. It should also be clear that many
modifications of this invention will occur to those skilled in the
art to which this invention relates. Accordingly, all such
modifications are included within the intended scope of the
invention as defined by the appended claims.
* * * * *