MOTOR
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor that is adapted to be applied to an electric power steering system for generating steering assist torque in a steering mechanism for example.
2. Description of the Related Art
In the past, there has been known a motor for an electric power steering system in which an electric current coming from outside through a connector connected to a tip end of a harness is supplied to an armature winding through the harness and a brush unit, whereby a shaft is caused to rotate under the action of a rotating electromagnetic force generated in the armature, and the rotational force of the shaft is supplied to a steering mechanism as steering assist torque (see, for instance, a first patent document: Japanese patent application laid-open No. 2000-197314).
In such an electric power steering system motor, the harness with the connector connected to its one end is connected at its other end with an insert plate of the brush unit by spot welding, whereby the connector, the harness and the brush unit are integrated with one another.
As a result, there is a need to arrange or provide a connector and a brush unit integrated with a new harness each time the specification of the harness is varied according to a user's request, thus posing the problem of troublesomeness or inconvenience in terms of parts control.
In addition, in an electric power steering system motor in which a connector, a harness and a brush unit integrated with one another are assembled to a motor main body, in order to detach these integrated ones from the motor main body in accordance with a change in the specification of the harness, it is necessary to destroy bearings, etc., attached to a shaft. As a

result, the specification of the harness can not be independently changed separately from the motor main body, and hence there is a need to set the kind or model of motor in accordance with the individual harness specification, so the number of motor models required is accordingly increased, thus giving rise to the problem of troublesomeness or inconvenience in terms of production control or management. SUMMARY OF THE INVENTION
Accordingly, the present invention is intended to obviate the problems as referred to above, and has its object to obtain a motor which is capable of eliminating the troublesomeness or inconvenience of parts control and product control according to a change in the specification of a harness.
Bearing the above object in mind, according to the present invention, there is provided a motor which includes: a bottomed cylindrical yoke having an opening portion formed therein; a shaft that is rotatably arranged in the yoke; an armature that is fixedly mounted on the shaft; a commutator that is fixedly mounted on one end of the shaft; a housing that is fixedly secured to the yoke in a manner to close the opening portion; a brush unit that has a brush received in a brush holder fixedly secured to a base which is fixedly attached to the housing and into which an insert plate is insert molded, the brush being in abutment at its tip end face with a surface of the commutator; and a connector that is inserted into the opening portion formed in the housing and has an insert conductor piece through which an electric current from outside flows. The insert conductor piece has a connector side terminal formed at one end thereof, the connector side terminal being electrically directly connected to a brush side terminal formed on the insert plate by means of a bonding element.
According to the motor of the present invention, the troublesomeness or inconvenience of parts control and product control according to a change in the specification of the harness can be eliminated.

The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross sectional side view showing a motor for an electric power steering system according to a first embodiment of the present invention.
Fig. 2 is a cross sectional front view of the electric power steering system motor in Fig. 1.
Fig. 3 is a front view when a brush unit in Fig. 1 is seen from the inside of the electric power steering system motor.
Fig. 4 is a front view showing the brush unit in Fig. 1.
Fig. 5 is a front view of a connector in Fig. 1.
Fig. 6 is a front view showing a brush unit in a motor for an electric power steering system according to a second embodiment of the present invention.
Fig. 7 is a front view showing a connector in the electric power steering system motor according to the second embodiment of the present invention.
Fig. 8 is a cross sectional side view showing a motor for an electric power steering system according to a third embodiment of the present invention.
Fig. 9 is a front view showing the electric power steering system motor in Fig. 8.
Fig. 10 is a front elevational view when a brush unit in Fig. 8 is seen from the inside of the electric power steering system motor.
Fig. 11 is a cross sectional side view of essential parts of the electric power steering system motor according to the third embodiment of the present invention.

Fig. 12 is a front view showing a motor for an electric power steering system according to a fourth embodiment of the present invention.
Fig. 13 is a front view showing a brush unit in the electric power steering system motor according to the fourth embodiment of the present invention.
Fig. 14 is a front view showing a connector in the electric power steering system motor according to the fourth embodiment of the present invention.
Fig. 15 is a cross sectional side view of essential parts of the electric power steering system motor according to the fourth embodiment of the present invention.
Fig. 16A is an enlarged view of an essential portion of Fig. 15.
Fig. 16B is an enlarged view of another essential portion of Fig. 15.
Fig. 17 is a cross sectional side view of essential parts of a motor for an electric power steering system according to a fifth embodiment of the present invention.
Fig. 18Ais an enlarged view of an essential portion of Fig. 17.
Fig. 18B is an enlarged view of another essential portion of Fig. 17.
Fig. 19 is a cross sectional side view showing a motor for an electric power steering system according to a sixth embodiment of the present invention.
Fig. 20 is a front view showing a connector in Fig. 19.
Fig. 21A is a side view of a grommet assembled to the connector in Fig. 20.
Fig. 21B is a plan view showing the grommet in Fig. 21 A.
Fig. 22 is a cross sectional side view showing a motor for an electric power steering system according to a seventh embodiment of the present invention.
Fig. 23 is a cross sectional front view of the electric power steering

system motor in Fig. 22.
Fig. 24 is a front view when a brush unit in Fig. 22 is seen from the inside of the electric power steering system motor.
Fig. 25 is a cross sectional side view of the electric power steering system motor according to the seventh embodiment of the present invention.
Fig. 26 is a front view showing that a grommet formed integral with an O ring part is fitted to a connector.
Fig. 27 is a front view showing that the grommet from which the O ring part in Fig. 26 is removed is fitted to the connector. DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, preferred embodiments of the present invention will be described in detail while referring to the accompanying drawings. Throughout respective figures, the same or corresponding members or parts are identified by the same reference numerals and characters. Embodiment 1.
Referring to the accompanying drawings and first to Fig. 1, there is shown a motor for an electric power steering system (hereinafter referred to as an electric motor) according to a first embodiment of the present invention. Fig. 2 is a front view of the electric motor in Fig. 1. Fig. 3 is a front view when a brush unit 12 in Fig. 1 is seen from the inside of the electric motor, and Fig. 4 is a front view that shows the brush unit 12 in Fig. 1.
In the electric motor, a field permanent magnet 2 having quadrupoles is fixedly arranged in opposition to an inner wall of a bottomed cylindrical yoke 1. In this yoke 1, a shaft 5 is rotatably supported at its opposite ends by a first bearing 3 and a second bearing 4. An armature 6 is fixedly secured to the shaft 5. A commutator 7 having a plurality of segments 7a is fixedly mounted on an end portion of the shaft 5. Also, a connecting member 26 is fixedly attached by press fitting to the second bearing 4 for the shaft 5 at a side opposite to the commutator 7.

A housing 8 is fixedly secured to an opening portion of the yoke 1 by means of clamp screws 9. The brush unit 12 is fastened to the housing 8 by means of clamp screws 11.
The armature 6 is provided with a core 24 that has a plurality of slots extending in an axial direction, and a winding 25 that is formed of a conductor arranged in the slots so as to be wound around the core in a plurality of turns.
In the brush unit 12, four brush holders 17 made of metal are fixedly secured to a base 16 into which an insert member in the form of an insert plate 15 is insert molded. In each of the brush holders 17, there is received a brush 14 that has its tip end placed in abutment against a surface of a segment 7a of the commutator 7 under the action of the resilient force of a spring 13. A lead 18 is connected at its one end to an intermediate portion of each brush 14, and at its other end to a portion of the insert plate 15 which is exposed to the outside. The insert plate 15 is formed with a pair of brush side terminals 15a which are exposed to the outside.
A connector 19 is fixedly secured to the housing 8 by means of clamp screws 20. The connector 19 is inserted at its one end into an opening portion 8a of the housing 8. A seal element in the form of an O ring 22 is arranged in a groove that is formed in an upper surface of the opening portion 8a of the housing 8. This O ring 22 is made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation by sealing between the housing 8 and the connector 19.
In addition, an O ring 23, which serves as a sealing element for sealing between the housing 8 and the yoke 1, is arranged between the housing 8 and the yoke 1. As such an O ring 23, too, there is used one made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation.
The connector 19 is an insert mold product into which an insert member in the form of an insert conductor piece 21 is insert molded. The

insert conductor piece 21 is formed at its tip end with a pair of female or concave connector side terminals 21a exposed to the outside.
The connector side terminals 21a and the brush side terminals 15a of the brush unit 12 are electrically and directly connected to each other through connection elements in the form of convex and concave connection or bonding.
In the electric motor as constructed above, an electric current from outside is supplied to the winding 25 of the armature 6 through the insert conductor piece 21 of the connector 19, the insert plate 15, the lead 18 and the segment 7a of the brush unit 12.
As a result, a rotating field is generated in the armature 6, whereby a rotational force is provided to the shaft 5 in cooperation with the field permanent magnet 2. The rotational force thus generated is supplied to a steering mechanism (not shown) as steering assist torque through the connecting member 26.
According to the electric motor of this embodiment, the connector side terminals 21a of the connector 19 are electrically connected directly to the brush side terminals 15a of brush unit 12, so a harness as conventionally required is made unnecessary. As a result, there becomes no need to arrange or provide a connector and a brush unit integrated with a new harness each time the specification of the harness is varied according to a user's request, and hence parts control can be made easily.
Also, there is no need to set an appropriate kind or model of electric motor according to each harness specification, so the number of model settings is accordingly reduced, thus making the management or control of production easy.
In addition, in case where there occurs a change in the specification of the connector 19 according to a change in the configuration, the lead-out direction, etc., of the insert conductor piece 21 connected to an outside

element or equipment for example, only the connector 19 of which the specification is changed need be replaced by a new one, and the motor main body of the electric motor except for the connector 19 can be used as it is, and hence the motor main body can be shared for common use.
Moreover, the connector 19 and the brush unit 12 can be electrically connected to each other with ease by inserting the male or convex brush side terminals 15a into the female or concave connector side terminals 21a, respectively.
Further, the O ring 22, which serves as a sealing element for sealing between the housing 8 and the connector 19, is arranged in the opening portion 8a of the housing 8, and the O ring 23, which serves as a sealing element for sealing between the housing 8 and the yoke 1, is arranged between the housing 8 and the yoke 1. Accordingly, the waterproofness of the electric motor can be ensured.
Furthermore, since the O rings 22, 23 are made of a vibration isolation material, it is possible to suppress the vibration and noise generated during the operation of the electric motor.
Here, note that it is possible to easily change the electric motor into one of a non-watertight type specification by removing the O rings 22, 23. Embodiment 2.
Hereinafter, reference will be made to an electric motor according to a second embodiment of the present invention while referring to Figs. 6 and 7, in which Fig. 6 is a front view showing a brush unit 30 of the electric motor, and Fig. 7 is a front view showing a connector 31 of the electric motor.
In this embodiment, an insert plate 32 of the brush unit 30 is formed with a pair of female or concave brush side terminals 32a which are exposed to the outside. The connector 31 is an insert mold product into which an insert member in the form of an insert conductor piece 33 is insert molded. The insert conductor piece 33 is formed at its tip end with a pair of male or

convex connector side terminals 33a that are exposed to the outside.
In this embodiment, the connector 31 and the brush unit 30 can be electrically connected to each other with ease by inserting the male or convex connector side terminals 33a into the female or concave brush side terminals 32a, respectively. The construction of this second embodiment other than the above is similar to that of the first embodiment.
According to the electric motor of this embodiment, the operation and effects similar to those of the first embodiment can be achieved. Embodiment 3.
Hereinafter, reference will be made to an electric motor according to a third embodiment of the present invention while referring to Figs. 8 through 10, in which Fig. 8 is a cross sectional side view of the electric motor; Fig. 9 is a front view of the electric motor in Fig. 8; and Fig. 10 is a front view when a brush unit 34 in Fig. 8 is seen from the inside of the electric motor.
In this embodiment, an insert plate 37 of the brush unit 34 is formed with a pair of brush side terminals in the form of brush side welding portions 37a that are exposed to the outside. A connector 35 is an insert mold product into which an insert member in the form of an insert conductor piece 36 is insert molded. The insert conductor piece 36 is formed at its tip end with a pair of connector side terminals in the form of connector side welding portions 36a that are exposed to the outside.
When an end of the connector 35 is inserted into an opening portion 8a of a housing 8, the connector side welding portions 36a and the brush side welding portions 37a are overlapped with each other. The connector side welding portions 36a and the brush side welding portions 37a, being overlapped with each other in this manner, are bonded to each other by Tig welding through joint holes 8b, as shown in Fig. 11. The construction of this third embodiment other than the above is similar to that of the first embodiment.

According to the electric motor of this embodiment, the connector side welding portions 36a and the brush side welding portions 37a are bonded to each other by bonding elements in the form of welding bonding, whereby the connector 35 and the brush unit 34 can be electrically connected to each other in an easy manner. The operation and effects of this third embodiment other than the above are similar to those of the first embodiment.
Here, note that the welding bonding may be, for example, soldering welding, projection welding, etc., other than Tig welding. Embodiment 4.
Hereinafter, reference will be made to an electric motor according to a fourth embodiment of the present invention while referring to Figs. 12 through 14, in which Fig. 12 is a front view of the electric motor; Fig. 13 is a front view showing a brush unit 38 of the electric motor; and Fig. 14 is a front view of a connector 39 shown in Fig. 12.
In this embodiment, an insert plate 40 of the brush unit 38 is formed with a pair of brush side terminals in the form of brush side joint or bonding portions 40a that are exposed to the outside. In each of the brush side bonding portions 40a, there is formed a brush side through hole 41 into which a cylindrical bush 42 is fitted.
The connector 39 is an insert mold product into which an insert member in the form of an insert conductor piece 43 is insert molded. The insert conductor piece 43 is formed at its tip end with a pair of connector side terminals in the form of connector side bonding portions 43a that are exposed to the outside. Each of the connector side bonding portions 43a has a connector side through hole 44 formed therein.
When an end of the connector 39 is inserted into an opening portion 8a of a housing 8, the connector side through holes 44 in the connector side bonding portions 43a and the corresponding brush side through holes 41 in the brush side bonding portions 40a are overlapped with one another. As shown

in Fig. 15 and Fig. 16A, rivets 45 are inserted into the thus overlapped through holes 44, 41 through corresponding joint holes 8b, and are then caulked whereby the connector 39 and the brush unit 38 are electrically connected to each other. Here, note that in the caulking process, the rivets 45 may be inserted into the through holes 44, 41 from the yoke 1 side depending upon the convenience of the production process.
In addition, a tapered portion 8d is formed at each corner of the opening portion 8a of the housing 8, as shown in Fig. 16B. A seal element in the form of an O ring 22 is arranged in each tapered portion 8d thus formed. The O ring 22 is made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation by sealing between the housing 8 and the connector 39. The construction of this fourth embodiment other than the above is similar to that of the first embodiment.
According to the electric motor of this embodiment, the connector side bonding portions 43a and the brush side bonding portions 40a are bonded to each other by bonding or joint elements in the form of rivet bonding, whereby the connector 39 and the brush unit 38 can be electrically connected to each other in an easy manner. The operation and effects of this fourth embodiment other than the above are similar to those of the first embodiment. Embodiment 5.
Hereinafter, reference will be made to an electric motor according to a fifth embodiment of the present invention while referring to Figs. 17, 18A, 18B, in which Fig. 17 is a cross sectional side view of essential parts of the electric motor, and Fig. 18A and Fig. 18B are enlarged views of essential portions of Fig. 17, respectively.
In this embodiment, connector side bonding portions 43a and brush side bonding portions 40a are bonded to each other by means of bonding elements in the form of screw bonding. Specifically, bushes 42A each having

a female thread formed on its cylindrical inner wall surface are fitted into brush side through holes 41 that are formed in a pair of brush side bonding portions 40a, respectively. Screws 47 are threaded into the bushes 42A, respectively, whereby a connector 46 and a brush unit 38 are electrically connected to each other.
In addition, the connector 46 has a groove 46a formed at an end portion thereof, and a seal element in the form of an O ring 43 is arranged in the groove 46a thus formed. The O ring 43 is made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation by sealing between a housing 8 and the connector 46. The construction of this fifth embodiment other than the above is similar to that of the fourth embodiment.
According to the electric motor of this embodiment, the connector side bonding portions 43a and the brush side bonding portions 40a are bonded to each other by bonding elements in the form of screw bonding, whereby the connector 46 and the brush unit 38 can be electrically connected to each other in an easy manner. The operation and effects of this fifth embodiment other than the above are similar to those of the fourth embodiment. Embodiment 6.
Hereinafter, reference will be made to an electric motor according to a sixth embodiment of the present invention while referring to Figs. 19, 20, 21 A, 21B, in which Fig. 19 is a cross sectional view of the electric motor; Fig. 20 is a front view of a connector 19 in Fig. 19; Fig. 21A is a front view of a grommet 50 in Fig. 19; and Fig. 21B is a plan view of the grommet 50 in Fig. 19.
In this embodiment, the grommet 50, which serves as a sealing element for sealing between a housing 8 and the connector 19, is arranged in an opening portion 8a of the housing 8. As such a grommet 50, there is used one made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation. The

construction of this sixth embodiment other than the above is similar to that of the first embodiment.
According to the electric motor of this embodiment, with the provision of the grommet 50, the waterproofness of the electric motor can be ensured, and at the same time, vibration and noise during the operation of the electric motor can be suppressed. The operation and effects of this sixth embodiment other than the above are similar to those of the first embodiment. Embodiment 7.
Hereinafter, reference will be made to an electric motor according to a seventh embodiment of the present invention while referring to Figs. 22 through 25, in which Fig. 22 is a cross sectional side view of the electric motor; Fig. 23 is a front view of the electric motor in Fig. 22; Fig. 24 is a front view when a brush unit 34 in Fig. 22 is seen from the inside of the electric motor; and Fig. 25 is a cross sectional view of essential parts of the electric motor shown in Fig. 22.
In this embodiment, a grommet 52 and an O ring part 52a are integrated with each other, as shown in Fig. 26.
In this embodiment, the grommet 52 is arranged in an opening portion 8a of a housing 8 so as to be used as a sealing element for sealing between the housing 8 and a connector 51, and the 0 ring part 52a is arranged between the housing 8 and a yoke 1 so as to be used as a sealing element for sealing between the housing 8 and the yoke 1. As the grommet 52 and the O ring part 52a thus integrated, there are used ones made of a waterproof and vibration isolating material such as, for example, rubber that can ensure waterproofness and vibration isolation. The construction of this seventh embodiment other than the above is similar to that of the third embodiment.
According to the electric motor of this embodiment, with the provision of the integrated grommet 52 and O ring 52a, the waterproofness of the electric motor can be ensured, and at the same time, vibration and noise

during the operation of the electric motor can be suppressed.
In addition, since the grommet 52 and the O ring part 52a are integrated with each other, assembly operations between the housing 8 and the connector 51 and between the housing 8 and the yoke 1 can be improved. The operation and effects of this seventh embodiment other than the above are similar to those of the third embodiment.
Here, note that in case of an electric motor of a non-watertight type specification, the grommet 52 excluding the O ring part 52a is applied, as shown in Fig. 27.
Moreover, beside a motor for an electric power steering system in which a connector side terminal and a brush side terminal are connected to each other by means of a bonding element in the form of welding bonding, the grommet 52 and the O ring part 52a can also of course be applied to a motor for an electric power steering system that uses either one of the bonding elements in the above-mentioned first, second, fourth and fifth embodiments of the present invention.
Although in the above-mentioned respective embodiments, reference has been made to the cases where the O rings 22, 23, 48 and the grommets 50, 52 are used as sealing elements, sealing between the housing 8 and the yoke 1 and between the housing 8 and each of the connectors 19, 31, 35, 38, 46, 51 can be made by coating these portions with a silicon-based resin as a sealing material for instance.
Further, although in the above-mentioned respective embodiments, a motor for an electric power steering system is used as a motor, the present invention is not of course limited to such a motor but instead can be applied to other motors.
While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.

What is claimed is:
1. A motor comprising:
a bottomed cylindrical yoke having an opening portion formed therein;
a shaft that is rotatably arranged in said yoke;
an armature that is fixedly mounted on said shaft;
a commutator that is fixedly mounted on one end of said shaft;
a housing that is fixedly secured to said yoke in a manner to close said opening portion;
a brush unit that has a brush received in a brush holder fixedly secured to a base which is fixedly attached to said housing and into which an insert plate is insert molded, said brush being in abutment at its tip end face with a surface of said commutator; and
a connector that is inserted into said opening portion formed in said housing and has an insert conductor piece through which an electric current from outside flows;
wherein said insert conductor piece has a connector side terminal formed at one end thereof, said connector side terminal being electrically directly connected to a brush side terminal formed on said insert plate by means of a bonding element.
2. The motor as set forth in claim 1, wherein said bonding element comprises convex and concave bonding.
3. The motor as set forth in claim 1, wherein said bonding element comprises screw bonding.
4. The motor as set forth in claim 1, wherein said bonding element comprises rivet bonding.
5. The motor as set forth in claim 1, wherein said bonding element comprises welding bonding.
6. The motor as set forth in claim 1, wherein a sealing element is

arranged in said opening portion of said housing for sealing between said housing and said connector.
7. The motor as set forth in claim 1, wherein a sealing element is
arranged between said housing and said yoke for sealing between said
housing and said yoke.
8. The motor as set forth in claim 6, wherein said sealing element
comprises an O ring.
9. The motor as set forth in claim 6, wherein said sealing element comprises a sealing material.
10. The motor as set forth in claim 6, wherein said sealing element comprises a grommet.
11. The motor as set forth in claim 1, wherein a grommet that is arranged
in said opening portion of said housing for sealing between said housing and
said connector, and an O ring part that is arranged between said housing and
said yoke for sealing between said housing and said yoke are integral with
each other.
12. The motor as set forth in claim 1, wherein said motor comprises a
motor for an electric power steering system.