Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1998-06-24
2001-09-11
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C029S596000, C029S513000, C029S505000, C310S049540, C403S279000
Reexamination Certificate
active
06288469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the technical field of an electric motor provided in a member device such as electrical equipment. More particularly, the invention provides a method and apparatus for fixing a brush holder to a holder stay.
2. Description of the Related Art
Generally speaking, some electric motors have feed members, such as brushes, brush holders within which the brushes movably fit, and a holder stay to which the brush holders are attached and fixed.
As shown in
FIG. 1
, some electric motors have a metal brush holder
2
with two pairs of fingers
2
d
formed to extend from both leg pieces
2
b
of the brush holder
2
so the fingers
2
b
face each other in parallel. The fingers
2
d
are then fixed to the holder stay
3
by first passing each finger
2
d
through a respective through hole
3
c
of the holder stay
3
. The through holes
3
c
are slot-shaped and formed in an attachment surface section
3
a
of the holder stay
3
. Each finger
2
b
is then bent along the back side of the attachment surface section
3
a
. As shown in
FIG. 2
, the fingers
2
d
are bent so that the fingers
2
d
face each other in a direction orthogonal to a longitudinal direction of the through holes
3
c
. In addition, the bent sections
2
h
of the fingers
2
d
are parallel to the longitudinal direction of the through holes
3
c.
Although conventional holder stays are formed with resin material, such as, for example, Bakelite and other such plastics, some holder stays have attachment surface sections
3
a
that are made of metal. The attachment surface sections
3
a
are made of metal to increase heat resistance and heat dissipation. However, when the fingers
2
d
of the brush holders
2
are fixed to the holder stay as described above, the attachment surface section
3
a
of the holder stay
3
that is made of metal has a decreased frictional resistance and weak fixing power because metal parts are fixed to metal parts.
Attempts have been made to increase the fixing power of such a holder stay
3
by increasing the press load at the time the fingers are being fixed. However, since the attachment surface section
3
a
of the holder stay
3
is made of metal, the attachment surface section becomes thinner than when the holder stay
3
is made of plastic. In addition, the spring-back characteristic of metal then becomes a problem. As a result, the fixing power is not particularly increased even if the press load is increased. Additionally, there is a limit as to how much of a press load can be applied because there is a possibility of deforming the holder stay
3
under the large press load.
SUMMARY OF THE INVENTION
The claimed invention is intended to overcome the shortcomings in the related art discussed above.
The invention includes fingers extending from a free end of respective leg pieces of a brush holder. Each finger is passed through a respective through hole provided in a surface section of a holder stay. Each finger is obliquely bent along the back face of the attachment surface section of the holder stay such that a finger section of each finger diagonally passes through the respective through hole. Because each finger passes through a respective through hole diagonally, side rims of each finger engage the periphery of each through hole whereupon the obliquely bent fingers are fixed.
Backlash of the fingers is regulated by the side rims of the fingers engaging the periphery of the through holes. As such, the fingers are fixed to the attachment surface section without backlash occurring even if both the brush holder and the attachment surface section of the holder stay are made of metal.
With this structure, by bending the fingers obliquely with respect to a longitudinal axis of the brush holder, the fingers are bent such that they are able to compensate for any occurrence of backlash. Therefore, it is possible to more securely fix the fingers to the back face of the attachment surface section of the holder stay without the backlash occurring.
The present invention performs the fixing through a first bending process in which the fingers are partially bent along the back face of the attachment surface section of the holder stay. A second bending process then completely bends the fingers along the attachment surface section of the holder stay. Furthermore, in the second bending process, the fingers are bent such that they are oblique to the longitudinal axis of the brush holder and as such, portions of each finger engage respective portions of the through holes such that the fixing may be performed without adding excessive stress to the fingers.
REFERENCES:
patent: 2561638 (1951-07-01), Richardson
patent: 3091838 (1963-06-01), Hild et al.
patent: 4691765 (1987-09-01), Wozniczka
patent: 6058018 (2000-05-01), Gerrits
Kimura Masakatsu
Ohtani Yasuo
Mitsuba Corporation
Oliff & Berridge, P.L.C
Tamai Karl
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