Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-07-31
2002-03-12
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S233000, C029S597000
Reexamination Certificate
active
06356004
ABSTRACT:
TECHNICAL FIELD
The invention is directed to a brush retainer for a DC motor, and more particularly to a brush retainer that prevents contact between the brushes and a commutator during motor assembly.
BACKGROUND ART
FIG. 1
is an exploded view of a portion of a known motor assembly
100
in which the inventive device will be used. Of particular interest with respect to this application is the interaction between a brush holder
102
, brushes (not shown) that are held in the brush holder
102
, armature shaft
106
, and commutator
108
. The brush holder
102
includes a center hole
110
for accommodating the armature shaft
106
and commutator
108
once the motor is completely assembled. The brushes are disposed around the center hole
110
and are spring-biased so that the brushes normally extend into the center hole
110
, as is known in the art.
Because the brushes are spring-biased to extend into the center hole
110
, positioning the brush holder
102
over the armature shaft
106
requires pushing the brushes against their spring bias with a brush retainer (not shown) to prevent the brushes from obstructing the center hole
110
and then releasing when the commutator
108
is seated in the center hole
110
so that the brushes can contact the commutator
108
firmly.
Current motor structures often position an armature spring (not shown) on the armature shaft
106
, which would pass through the center hole
110
during assembly. At times, however, the spring on the armature shaft
106
will contact the brush retainer and moves the retainer as the shaft
106
passes through the center hole
110
, releasing the brushes prematurely before the commutator
108
is seated properly within the center hole
110
.
There is a need for a device that retains brushes during assembly without experiencing the premature brush release problems of known devices.
SUMMARY OF THE INVENTION
Accordingly, the present invention is a combination brush retainer/spring assembly that includes a retaining ring connected to a spring to form a unitary device. The retaining ring is positioned in a center hole of a brush retainer and holds a plurality of brushes against their spring bias to prevent the brushes from obstructing an armature shaft as it passes through the center hole. Once the commutator is properly seated the center hole, the retaining ring is pushed away by the commutator to release the brushes.
After assembly, the conical spring is disposed on the armature shaft between the retaining ring and a ball bearing that is slip-fitted over the armature shaft. Once the motor is completely assembled, the conical spring is compressed so that a narrow end of the spring engages with an inner race of the ball bearing. The spring force in the conical spring forces the armature shaft and the ball bearing to rotate together at the same angular velocity without any slippage.
By connecting the retaining ring and the conical spring into a single brush retainer/spring assembly, the present invention prevents the brushes from releasing prematurely and blocking the center hole. Further, integrating the conical spring with the retaining ring into a unitary assembly allows the same assembly to retain the brushes and engage with the inner race of the ball bearing, thereby making brush retention more reliable and streamlining the manufacturing process.
REFERENCES:
patent: 1027273 (1912-05-01), Nelson
patent: 4774754 (1988-10-01), Steward, Sr.
patent: 4820139 (1989-04-01), Tuckey
patent: 5130751 (1992-07-01), Sato et al.
patent: 5172465 (1992-12-01), Stewart, Sr.
patent: 5495134 (1996-02-01), Rosenblum
patent: 5821662 (1998-10-01), Kajino et al.
patent: 5977683 (1999-11-01), Scheele et al.
patent: 2581260 (1986-10-01), None
Andrews Gary
Burtis Robert L.
Lombardo Frank
Porter Eugene B.
Strausburg Larry
Perez Guillermo
Ramirez Nestor
Valeo Electrical Systems, Inc.
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