JP2013236521 | DC MOTOR |
CLARKE MICHAEL T
US4293789A | 1981-10-06 | |||
US4694214A | 1987-09-15 | |||
US5004943A | 1991-04-02 | |||
US4866322A | 1989-09-12 | |||
US5006747A | 1991-04-09 | |||
FR2625628A1 | 1989-07-07 | |||
JPH0446545A | 1992-02-17 | |||
EP0148702A2 | 1985-07-17 |
1. | ctric motor comprising: a drive shaft, an armature and commutator assembly fixed on said drive shaft, a housing disposed around said assembly, magnet means disposed between said assembly and said housing, an endframe fixed to said housing, said endframe having therein a journal, a bearing mounted in said journal and supporting said drive shaft, brush means in contact with a commutator portion of said assembly, brush tubes for slidably retaining said brush means, and for retaining spring means urging said brush means into engagement with said commutator portion, and a brush retainer mounted on said journal and having a face portion overlying a face portion of said bearing, said journal having ribs on an exterior wall thereof and extending axially thereof, said retainer being of plastic, said journal ribs and said plastic retainer being configured such that said retainer is held on said journal by said ribs in nonrotative fashion, said retainer face portion abutting an end of said commutator portion The motor in accordance with claim 1 wherein said brush retainer is provided with a rub ring on said face portion thereof for contact with said motor commutator portion. |
2. | The motor in accordance with claim 1 wherein said brush retainer is provided with a cylindricallyshaped wall portion, said face portion of said retainer extending inwardly from an edge of said wall portion and defining a central opening in which is disposed said motor drive shaft. |
3. | The motor in accordance with claim 3 wherein an interior surface of said retainer wall portion is engaged with said journal ribs so as to prevent rotation of said retainer on said journal. |
4. | The motor in accordance with claim 4 wherein there is disposed in said endframe a brush card having a cylindricallyshaped central portion encircling said commutator portion, said brush tubes extending outwardly from said central portion, an exterior surface of said retainer wall portion being adjacent an interior surface of said central portion and removed from said brush means. |
5. | The motor in accordance with claim 5 wherein said retainer is provided with an annular protrusion extending from said retainer face portion and in contact with an end of said motor commutator portion. |
6. | An endframe assembly for an electric motor, the assembly comprising: a housing member, a journal formed in said housing member, a bearing mounted in said journal for supporting a drive shaft of said motor, a brush assembly disposed in said housing member and comprising a cylindricallyshaped central portion, and brush tubes extending radially outwardly from said central portion, a brush slidably disposed in each of said brush tubes, a spring disposed in each of said brush tubes for urging said brush toward an open end of said brush tube for engaging a commutator portion of said motor, and a cylindricallyshaped brush retainer mounted in said central portion and positioned so as to abut said brushes and thereby prevent movement of said brushes out of their respective brush tubes, and so as to be movable onto said journal axially, to disengage from said brushes to permit said brushes to engage said motor commutator portion. |
7. | The assembly in accordance with claim 7 wherein said journal is provided with ribs on an exterior surface thereof, said retainer is of plastic material, and an interior surface of said retainer is engageable with said ribs to prevent rotation of said retainer on said journal. |
8. | The assembly in accordance with claim 8 wherein said ribs extend axially of said journal and permit axial movement of said retainer on said journal. |
9. | The assembly in accordance with claim 8 wherein an exterior surface of said retainer is engaged with said brushes. |
10. | 1The assembly in accordance with claim 10 wherein said retainer is provided with a face portion for overlying a face portion of said bearing upon movement of said retainer to disengage from said brushes. |
11. | The assembly in accordance with claim 1 1 wherein said retainer face portion is provided with an annular protrusion extending therefrom for engaging an end of said motor commutator portion. |
Background of the Invention
1 . Field of the Invention
The invention relates to electric motors and is directed more particularly
to an electric motor having in an endframe portion thereof a brush retainer.
2. Description of the Prior Art
In electric motors, brushes are commonly retained in brush tubes which
usually are molded integrally with a plastic endframe portion of the motor. The
endframe and brush tubes typically are of a plastic material. The brush tubes
are square in cross-section and hollow, somewhat like elevator shafts, in which
spring-biased brushes are slidably movable into engagement with the
commutator of the motor.
In assembly of such motors, it is common that a coil spring is inserted in
a brush tube and, thereafter, a brush, with a shunt attached thereto, is inserted
in the brush tube on top of the spring. In shipment and handling prior to
assembly, it is sometimes the case that the brush and spring fall out of the open
end of the tube. At the final assembly point, the brush and spring must be
reinserted and properly positioned in the brush tube. It is on occasion
overlooked that the spring is missing. It is usually apparent when the brush is
missing, but sometimes the brush is replaced without the absence of the spring
having been noticed. In some instances, the shunt will, for a limited time,
exercise spring-like properties and hold the brush in a commutator-engaging position. However, the shunt usually cannot maintain its spring-like
performance and, in due course, the brush falls away from commutator
engagement, terminating proper operation of the motor.
Accordingly, at best, replacement of a missing brush, or both brush and
spring, occasions delay in the assembly process, and, at worst, can result in
assembly of a faulty motor. There is then, a need for a brush retainer which
prevents loss of brushes and brush springs from brush tubes.
When the brushes remain in their proper positions, they still occasion time
delays at the assembly point. The brushes, which are under spring pressure
urging them toward the open ends of their brush tubes, typically extend beyond
the open ends of the brush tubes and must be urged back into the brush tubes
fully to allow a commutator to assume its rightful position in the endframe.
Operators usually use plier-like tools to spread the brushes apart, to permit
insertion of the commutator. Once the commutator is in place, the plier-like tool is removed, allowing the brushes to snap into engagement with the
commutator.
In the endframe there is provided means for retaining a bearing which, in
turn, retains a portion of the drive shaft of the motor. A face of the bearing,
which usually is of metal, receives a metal face of the commutator. In
operation, the commutator face moves rotatably against the bearing face and
generates noise. In some applications, it is desirable that the motor operate as
quietly as possible. For example, in motors for operating automobile power
seats, it is necessary that the motor run quietly so as not to introduce irritating
noises into the automobile passenger compartment.
Thus, there is a need for means to substantially reduce the noise
generated at the commutator-bearing interface.
Summary of the Invention
It is, therefor, an object of the invention to provide an electric motor
having means for retaining the brushes in place in the brush tubes during
shipment and/or handling prior to final assembly.
A further object of the invention is to provide such retaining means as will retain the brushes in a position in which receipt of the commutator by the
brush tube assembly may be accomplished without having to move the brushes
out of the way.
A still further object of the invention is to provide such retaining means
which, upon positioning of the commutator in proper brush-engaging position, will thereafter function as a thrust washer disposed between the bearing and
the commutator, to provide for reduction of noise occasioned by the operation
of the motor.
With the above and other objects in view, as will hereinafter appear, a
feature of the present invention is the provision of an electric motor comprising
a drive shaft, an armature and commutator assembly fixed on the drive shaft, a
housing disposed around the armature and commutator assembly, magnet
means disposed between the armature and commutator assembly and the
housing, and an endframe fixed to the housing. There is provided in the endframe a journal and a bearing mounted in the journal, the bearing supporting
the drive shaft. Further disposed in the endframe are brush means in contact
with a commutator portion of the assembly, and brush tubes for slidably
retaining the brush means and for retaining spring means urging the brush
means into engagement with the commutator. The motor is characterized by a
brush retainer mounted on the journal and having a face portion overlying a face
portion of the bearing. The journal is provided with ribs on an exterior wall
thereof and extending axially thereof. The retainer is of plastic and the journal
ribs and plastic retainer are configured such that the retainer is held on the
journal by the ribs in a non-rotative fashion with the retainer face portion
abutting an end of the commutator portion.
In accordance with a further feature of the invention, there is provided an endframe assembly for an electric motor, the assembly comprising a housing
member, a journal formed in the housing member, and a bearing mounted in the
journal for supporting a drive shaft of the motor. In the endframe there is
disposed a brush assembly including a cylindrically-shaped central portion, brush
tubes extending radially outwardly from the central portion, a brush slidably
disposed in each of the brush tubes, and a spring disposed in each of the brush
tubes for urging the brush toward an open end of the brush tube for engaging a
commutator portion of the motor. The endframe assembly is characterized by a
cylindrically-shaped brush retainer mounted in the central portion and positioned
so as to abut the brushes to prevent movement of the brushes out of their
respective brush tubes, and so as to be movable onto the journal axially thereof
to disengage from the brushes, to permit the brushes to engage the motor commutator portion.
The above and other features of the invention, including various novel
details of construction and combinations of parts, will now be more particularly
described with reference to the accompanying drawings and pointed out in the
claims. It will be understood that the particular devices embodying the
invention are shown by way of illustration only and not as limitations of the
invention. The principles and features of this invention may be employed in
various and numerous embodiments without departing from the scope of the
invention.
Brief Description of the Drawings
Reference is made to the accompanying drawings in which is shown an
illustrative embodiment of the invention, from which its novel features and
advantages will be apparent.
In the drawings:
Fig. 1 is a partly side elevational, partly sectional, view of one form of
motor illustrative of an embodiment of the invention;
Fig. 2 is an elevational view of an endframe portion of the motor shown
in Fig. 1 , taken from the open end of the endframe;
Fig. 3 is a sectional view of the endframe of Fig. 2;
Fig. 4 is similar to Fig. 2, but shows the endframe portion with additional
components therein;
Fig. 5 is similar to Fig. 3 but shows the endframe portion with additional components therein; and
Fig. 6 is similar to Fig. 4, but shows the endframe portion with
components in altered positions.
Description of the Preferred Embodiment
Referring to Fig. 1 , it will be seen that the illustrative motor includes a
drive shaft 10. Fixed to the drive shaft 10 is an armature and commutator
assembly 1 2, including an armature 14, a commutator 1 6, and appropriate
windings 1 8.
A metal housing shell 20, preferably of steel, is disposed around the
armature 14. Permanent magnets 22 are disposed between the housing shell 20 and the armature 14 and are secured to the housing shell.
An endframe 30 of noise-absorbing plastic material, is fixed to the
housing shell 20. The endframe 30 has formed in a substantially closed end 32
a journal 34 (Figs. 1 -6) for retaining a bearing 36 which, in turn, supports the drive shaft 1 0.
Disposed in the endframe 30 is a discrete brush card 40 (Figs. 1 and 4-6)
which comprises a cylindrically-shaped central portion 42 configured to retain
the commutator 1 6 and to be disposed concentrically around the journal 34
(Fig. 1 ) . Extending radially from the central portion 42 are opposed brush tubes
44 (Figs. 1 and 4-6). The central portion 42 and the brush tubes 44 are of
plastic and may be formed integrally. Each of the brush tubes 44 has disposed
therein a coil spring 46 and a brush 48, the spring 46 biasing the brush 48 into
engagement with the commutator 16 disposed centrally of the brush card
central portion 42 (Fig. 1 ). Each brush 48 has attached thereto a conductive
wire lead, or shunt 50, the other end of which is connected to a terminal 52
(Figs. 4 and 6).
Referring again to Fig. 1 , it will be seen that the endframe 30 extends
axially of the motor a sufficient distance to provide a plastic shell housing 56,
comprising a side wall portion 58 of the endframe 30, around the commutator
16. The side wall portion 58 of the endframe 30 extends towards the armature
14 such that the commutator 16 is disposed fully within the plastic endframe
30 and is axially spaced from an open end 60 of the endframe 30 and from the metal shell 20. Thus, the noise-absorbing plastic shell housing 56 extends well
beyond either end of the commutator to absorb radiated noise generated by the
commutator-brush interface.
As may be seen in Figs. 1 and 4-6, the brush card 40 is provided with
flat tabs 62 having orifices 64 (Figs. 1 and 5) therethrough. Elastomeric
grommets 66 are mounted on the tabs 62 and in and around the orifices 64, the
grommets 66 having openings 68 therein which are aligned, respectively, with
the orifices 64.
In assembly of the endframe 30 and brush card 40, the grommets 66 of
the brush card 40 are aligned with posts 70 extending from the closed end 32
of the endframe (Figs. 1 and 5) to securely lock the brush card 40 to the
endframe 30, but with the brush card isolated from the endframe by the
elastomeric grommets. Thus, the noise generated at the interface of the
brushes 48 and commutator 1 6 is not transmitted to the endframe, but, instead, is radiated from the commutator and, to a large degree, absorbed by
the endframe side wall 58 and endframe end wall 32.
Referring again to Fig. 1 , it will be seen that in the endframe 30 there is
disposed a collar member 80, referred to as a "brush retainer" for reasons to be
made clear hereinafter. The brush retainer 80 is mounted on the journal 34 and
is provided with a face portion 82 overlying a face portion 38 of the bearing 36.
The face portion 82 of the retainer 80 extends inwardly from an edge of a
cylindrically-shaped wall portion 90 of the retainer 80 and defines a central
opening 94 in which is disposed the motor shaft 10. The journal 34 is provided
with ribs 84 upstanding therefrom and extending axially thereof. The retainer
80 is of a plastic material which receives the ribs 84 such that the retainer 80 is
held on the journal 34 in a non-rotative fashion. The retainer face portion 82
abuts a phenolic endplate 24 of the commutator 1 6. From the retainer face
portion 82 there protrudes an annular ring 86 molded integrally with the retainer
face portion 82. The ring 86 is customarily referred to as a "rub ring." As the
commutator 1 6 rotates in operation, the commutator endplate 24 rides on the
rub ring 86. Inasmuch as the retainer 80, including the rub ring 86, is of
plastic, the interface between the phenolic endplate 24 and the retainer 80
generates little noise.
Thus, the elongated endframe 30, absorbing noise from the commutator-
brush interfaces, the isolated brush card 40, and the plastic rub ring 86,
cooperate to provide a motor which, in operation, runs very quietly.
The brush retainer serves still another valuable purpose. In assembly of
the endframe 30, including the brush card and related components, the retainer
80 is placed in the brush card central portion 42 such that an exterior surface
88 of the central portion cylindrically-shaped wall 90 blocks open ends 92 of
the brush tubes 44 to prevent loss of the brushes 48 through the open ends
(Figs. 4 and 5). The spring-biased brushes 48 bear against the surface 88 of
the wall 90 to hold the retainer 80 in place. The endframe 30 may then be
shipped to an assembly location, or otherwise handled prior to final motor
assembly, without fear of brush loss prior to assembly.
Upon final assembly, the commutator 1 6 of the motor is inserted in the
brush card central portion 42, pushing the retainer 80 from the position shown
in Figs. 4 and 5 to the position shown in Figs. 1 and 6. An interior surface 96 of the retainer cylindrically-shaped wall 90 engages the ribs 84 on the journal
34, but may be moved axially, along the length of the ribs 84. At this point the
retainer 80 changes functionally from a "brush retainer" (Figs. 4 and 5) to a
thrust washer (Figs. 1 and 6). As the retainer 80 is pushed from the brushes
48, the spring-biased brushes snap into position abutting the commutator 1 6 (Fig. 1 ).
Accordingly, there is provided a retainer which serves to expedite
assembly of the motor, serves to insure against loss of brushes and/or assembly
of motors without springs, and serves to reduce noise of operation normally
associated with the commutator-bearing interface.
It is to be understood that the present invention is by no means limited to
the particular construction herein disclosed an/or shown in the drawings, but
also comprises any modifications or equivalents within the scope of the claims.
Having thus described our invention, what we claim as new and desire to
secure by Letters Patent of the United States is:
Next Patent: METHOD AND APPARATUS FOR CONTROLLING AN AC HIGH-FREQUENCY MOTOR