Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-08-31
2004-09-21
Lam, Thanh (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S239000
Reexamination Certificate
active
06794787
ABSTRACT:
TECHNICAL FIELD
The present invention herein resides generally in the art of motor assemblies. In particular, the present invention relates to bypass motor fan assemblies which employ a vent cover. Specifically, the present invention is directed to a brush clamp clip that functions to hold a motor brush in place while also retaining the vent cover to the motor assembly.
BACKGROUND ART
Bypass motor fan assemblies are used in various types of industrial and commercial applications. One of their more common applications is for vacuum devices wherein a fan is rotated by a motor shaft to draw working air into a housing and wherein the air is exhausted radially out the housing. This working air does not come in contact with the motor windings and as such is normally dirt-free and moisture-free. In order for the motor assembly to operate properly the motor is cooled by at least one cooling fan that is driven by the same motor shaft.
In order to ensure the safe operation of the motor cooling fan, a vent cover is disposed over the cooling fan and attached to the motor assembly to prevent foreign objects from interfering with the rotation of the fan and to keep other foreign matter away from the motor assembly. In the past, these vent covers were secured to a motor holding bracket by a friction fit. For those vent covers which are secured only by frictional forces it has been found that the vent cover is easily dislodged and accordingly poses a safety and reliability problem.
One solution for retaining the vent cover to the motor assembly is shown in
FIGS. 1-7
. As can be seen in the drawings, a bypass motor fan assembly is designated generally by the numeral
20
. The assembly
20
includes a fan housing
22
which is secured to a fan end bracket
24
. Secured to an opposite side of the fan end bracket
24
is a motor assembly
26
which provides a rotating shaft which rotates a fan (not shown) that is enclosed by the fan housing
22
. The motor assembly
26
includes a motor bracket
28
which carries at least a pair of motor brushes
30
which are in contact with the commutator of the motor assembly
26
. As used herein, reference to motor brush
30
, may be to just a brush or to a sleeve-type housing which carries and spring biases the brush. A cooling fan (not shown) is rotated by the motor shaft and is carried at the end of the shaft opposite the working air fan. The brush
30
is secured to the motor bracket
28
by a brush clamp
40
. As best seen in
FIGS. 2-4
, the brush clamp
40
is an inverted U-shaped metallic piece which has a top member
42
which may be provided with a detent
44
that retains the motor brush
30
in place. Downwardly extending from the edges of the top member
42
are a pair of sides
46
from which perpendicularly extend a flange
48
. Flange holes
50
extend through the flanges
48
to allow for receipt of fasteners
52
which secure the brush clamp
40
to the motor bracket and which allow for retention of the motor brush
30
.
After the brush clamp
40
is secured to the motor bracket to retain the motor brush
30
, the vent cover
32
is positioned over the motor bracket and axially positioned in a proper orientation to permit a friction fit between the vent cover
32
and the motor bracket
28
. A prior art clip, designated generally by the numeral
60
, as best seen on the left side of FIG.
1
and in
FIGS. 5-7
, is installed radially to secure the vent cover
32
to the brush clamp
40
and the motor bracket
28
.
The clip
60
includes a leg portion
62
from which substantially perpendicularly extends a foot
64
. Further extending in the same direction as the foot
64
are a pair of tines
66
which form a slot
68
. Extending substantially perpendicularly from the leg portion
62
is a shoulder portion
70
. Further extending from the shoulder portion is a bend
72
which has a downwardly extending tab
74
. The tab
74
preferably extends in a direction toward the leg portion
62
.
It will be appreciated that the tines
66
are inserted between the top member
42
and the top surface of the motor brush
30
. The slot
68
receives the detent
44
such that the clip
60
may be fully inserted into the brush clamp
40
. As the clip
60
is radially directed between the brush clamp
40
and the brush
30
, the bend portion
72
contacts a portion of the vent cover and is primarily deflected or pivoted at the shoulder portion
70
until a clearance is obtained and the shoulder portion
70
returns to its original position. The tab
74
functions to hold onto a corresponding surface of the vent cover and as such the clip cannot be radially withdrawn until the shoulder portion
70
is pivoted upwardly, and the tab
74
no longer contacts the vent cover
32
.
Although the prior art clip
60
is effective, several drawbacks have come to light. It has been found that the clip
60
retains the vent cover in such a manner that makes it difficult to service or repair the cooling fan or any component of the motor assembly. This is primarily attributable to the fact that the bend portion
72
must be pivoted upwardly at the shoulder portion
70
while simultaneously applying an outward radial force. Such a procedure is quite difficult and often results in breakage of the clip on the vent cover at the shoulder portion of the clip. It has also been found that manually installing the clip
60
in a manufacturing environment leads to concerns about repetitive motion stresses to the worker who is installing the clips. It has also been found that the clips
60
are sometimes difficult to align and, as such, the vent cover may not be properly secured to the motor bracket as required for safe operation of the attached motor fan assembly.
Therefore, based upon the foregoing, there is a need in the art for a more reliable way to secure a vent cover to a motor assembly and to provide a clip or retention device that is more reliable in operation and in installation.
SUMMARY OF THE INVENTION
Therefore, it is a first aspect of the present invention to provide a bypass motor fan assembly having a vent cover retention clip, comprising a motor assembly having a motor bracket which carries at least a pair of motor brushes; a vent cover coupled to said motor assembly; and an integral clip secured to said motor bracket for slidably retaining said motor brushes and for retaining said vent cover to said motor bracket.
Another aspect of the present invention, which shall become apparent as the detailed description proceeds, is an integral brush clamp and vent cover retention clip for retaining a vent cover to a motor assembly, comprising a brush clamp attachable to the motor assembly; and a deflectable finger integrally extending from said brush clamp, said deflectable finger securable to the vent cover, wherein said deflectable finger is pivotable with respect to said brush clamp.
Other aspects of the present invention are attained by a method for assembling a motor assembly having a vent cover, comprising assembling a motor assembly having a motor bracket; retaining at least one motor brush to said motor bracket with an integral brush clamp and vent cover retention clip; and pressing a vent cover on to said motor bracket after said clamping step such that said clip retains said vent cover.
REFERENCES:
patent: 3902088 (1975-08-01), Guglielmo
patent: 5642012 (1997-06-01), Boggs, III
patent: 5736805 (1998-04-01), Hyatt et al.
Ametek Inc.
Lam Thanh
Renner Kenner Greive Bobak Taylor & Weber
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