JP4379101B2 - Electric power steering device - Google Patents

Description

  The present invention relates to a mounting structure for an assist motor used in an electric power steering apparatus.

  Generally, an electric power steering apparatus includes an electric motor for assisting the steering force of the steering wheel, and controls the driving of the electric motor according to a torque detection signal detected by a torque sensor provided in the steering system. It has become.

  In this type of electric power steering apparatus, as shown in FIG. 7, the electric motor 51 is provided in a gear box or the like of the steering column 52, and assists the steering shaft 53 via a speed reduction mechanism. Further, the steering column 52 is attached between the vehicle body frame 54 and the dash panel 55 by mounting brackets 56 and 56 due to space constraints.

  For example, as shown in FIG. 8, this type of electric motor 51 is provided in a steering column 52 and assists steering of a steering shaft 53 via a speed reduction mechanism in a gear box 57. ing. A flange portion 58 is formed at the end of the steering column 52 so as to protrude outward from the gear box 57, and the electric motor 51 is attached to the gear box 57 via the flange portion 58. At that time, the electric motor 51 is provided in the gear box 57 in a state of traveling on the outside of the steering column 52, and the wire harness 59 from the electric motor 51 is lateral to the motor case 60, that is, with respect to the motor shaft. Are arranged so as to be pulled out in a right angle direction (right side in FIG. 8).

  For example, in Patent Document 2, as shown in FIG. 9, in the electric motor 71, a motor shaft 73 is rotatably supported by a pair of bearings 74 and 74 at both ends in a cylindrical case 72. An armature 75 is disposed around the motor shaft 73, and a commutator 76 is attached to one end thereof. A brush 78 is brought into contact with the surface of the commutator 76 by the elasticity of the spring 77. A brush holder 79 that holds the brush 78 is fastened to the bracket 90 by bolts 91.

  A grommet 80 is attached to the motor case 72 of the electric motor 71 by fitting, and a wire harness 81 extends outward from the grommet 80. That is, also in this example, the wire harness 81 is pulled out from the electric motor 71 to the side, that is, in a direction perpendicular to the motor shaft 73 (downward in FIG. 9).

  As a result, in the above-described conventional electric motor, the wire harnesses 59 and 81 are pulled out to the side of the motor, and the pulling direction is perpendicular to the output shaft of the electric motors 51 and 71, that is, outside in the radial direction. It has a structure like this.

JP 2001-180506 A JP 2000-166169 A

  However, in the mounting structure of the electric motor as described above, the electric motors 51 and 71 are mounted in a state of traveling on the outside in the radial direction from the steering column 52, and the mounting state of the motors 51 and 71 is the mounting layout. There was a problem from the viewpoint.

  In particular, the direction in which the wire harnesses 59 and 81 are drawn is a direction perpendicular to the output shaft of the electric motors 51 and 71, that is, is drawn radially outward from the motor cases 60 and 72. In some cases, it was necessary to bend the wire harnesses 59 and 81 extremely.

  For this reason, the layout of the motors 51 and 71 is a great restriction, and a large current of several tens of amperes flows through the wire harnesses 59 and 81 used in the electric power steering apparatus. , 81 may be severely broken due to cracks in the sheath of the harness or deterioration of the sealing performance.

  Further, when the wire harnesses 59 and 81 are drawn from the motors 51 and 71, the wire harnesses 59 and 81 are loosened from the drawn portion and are arranged around the gear box. Therefore, when the EPS is attached to the vehicle body, the operator accidentally touches the wire harness 59 or 81, or the wire harness vibrates due to vibration or impact during transportation or traveling vibration after mounting the EPS. A large tension or impact may be generated in the harnesses 59 and 81, and a large impact force may be generated in the connector portions of the motors 51 and 71. Therefore, the connector portions of the motors 51 and 71 are damaged, and foreign matter such as water and dust may enter from the damaged portions, which may cause a failure.

  Accordingly, an object of the present invention is to improve the mounting structure of a motor and the wiring structure of a wire harness used in an electric power steering device, and to make the wire harness pull-out direction substantially the same as the output shaft of the motor. By wiring in a state in which the drawing of the wire is regulated, the space required for drawing the wire harness is reduced, the attachment structure of the wire harness is strengthened, and the layout of the apparatus is improved.

  In view of the above, an object of the present invention is to provide an electric power steering apparatus in which a motor is provided in a gear box and the steering shaft is assisted by driving the motor via a reduction gear in the gear box. This is achieved by providing a wire harness lead-out portion, pulling out the wire harness from the lead-out portion toward the reduction gear, and making the wire harness pull-out direction substantially the same as the motor shaft.

  Further, the above object is effectively achieved by the connector being provided on the side of the reduction gear from the bracket and projecting in substantially the same direction as the motor shaft.

  Further, the object is to arrange the brush holder in the bracket, to form the connector insertion hole in the bracket, and to insert the connector protruding from the brush holder into the insertion hole. Through this, the wire harness is effectively pulled out in the same direction as the motor shaft on the speed reduction gear side.

  Moreover, the said objective is effectively achieved by the said connector being integrally molded with the said brush holder and resin.

  Further, the object is to form the bracket integrally with the gear box, and provide a pull-out portion of the wire harness in the gear box, the pull-out direction of the wire harness being on the speed reduction gear side, and the motor shaft This is achieved by having the same direction.

  Also, the object is effectively achieved by the drawing portion being a connector protruding from the gear box on the speed reduction gear side in substantially the same direction as the motor shaft.

  Moreover, the said objective is achieved more effectively by having arrange | positioned the said drawer | drawing-out part on the opposite side to the brush supported by the brush holder within a motor case.

  Further, the object is to provide the gear box with a fixing portion of the wire harness drawn from the drawing portion, and the wire harness extending from the drawing portion positions the fixing portion on an extension line in the drawing direction of the wire harness. This is achieved more effectively.

  In addition, the above-described object is that the fixing portion includes a harness fixing bracket, which is fixed to a sensor cover of a sensor housing provided in the gear box at one end and fixes the wire harness at the other end. This is achieved more effectively.

  As described above, according to the electric power steering apparatus according to the present invention, in the electric power steering apparatus including the assist motor in the gear box, the wire harness is pulled out from the motor bracket to the gear box side, and the pull-out direction of the wire harness is changed. The direction was almost the same as the motor shaft. As a result, the drawing direction of the wire harness of the electric motor, that is, the drawing direction of the brush holder from the connector is on the gear box side and substantially the same direction as the motor shaft. Therefore, there is no protrusion in the space outside the motor shaft in the radial direction around the electric motor, and the drawing direction of the wire harness is drawn out to the gear box side and provided on the side opposite to the brush installation position. Therefore, the influence of noise due to brush discharge or the like is reduced, and interference with other devices is eliminated by pulling out the wire harness. As a result, space can be used effectively, the layout of the apparatus can be improved, and the wire harness can be pulled out from the connector without difficulty.

  Furthermore, the wire harness is fixed by a bracket at a position on the extension line in the pull-out direction from the pull-out portion, and even if a large vibration or impact acts on the wire harness when the EPS is installed or running, the wire harness is The wire harness extending to the bracket does not generate excessive tension or stress due to bending or deformation. For this reason, the connector portion of the wire harness is not damaged, and foreign matters such as water and dust do not enter the motor, thereby improving the durability of the apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an external appearance of an electric power steering apparatus according to a first embodiment of the present invention. In FIG. 1, 1 is a pinion shaft connected to a steering wheel (not shown). Further, the rack column 1 'is provided with an electric motor 2 for assisting steering. The electric motor 2 is a gear box 4 as a speed reduction mechanism arranged on the motor shaft side, that is, on the output shaft side (left side in FIG. 1). It is fixed to.

  The gear box 4 houses a reduction gear provided on the pinion shaft 1, and the reduction gear meshes with a worm (not shown) mounted on the motor shaft of the electric motor 2, whereby the electric motor 2. The rotation of the motor is decelerated to assist the pinion shaft 1.

  As shown in FIG. 2, a connector 5 having a substantially elliptical cross section is provided on the output shaft side end surface of the electric motor 2, and a connecting pin 7 for connecting to the wire harness 6 is provided therein. The wire harness 6 is connected to the connector. As shown in FIG. 2, the connector 5 extends from the outside of the motor output shaft side end surface in substantially the same direction as the motor shaft 3 (front side in FIG. 2). Further, the wire harness 6 is drawn not to the motor 2 side but to the gear box 4 side as a speed reduction mechanism in order to facilitate attachment and detachment from the viewpoint of the vehicle body space. As a result, the wire harness 6 connected to the connection piece 7 of the connector 5 is pulled out from the gear box 4 side of the electric motor 2 in the same direction (substantially parallel) to the output shaft of the electric motor 2, that is, the motor shaft 3. It has such a structure.

  Reference numeral 8 denotes a bolt for attaching the electric motor 2 to the gear box 4.

  Therefore, since the wire harness 6 is pulled out in substantially the same direction as the motor shaft 3, the space on the outside in the direction perpendicular to the motor shaft 3 can be used effectively. That is, when the wire harness 6 is pulled out in the radial direction with respect to the motor shaft 3 as in the prior art, the wire harness 6 may protrude and hinder the layout of the apparatus. On the other hand, the wire harness 6 drawn out in the same direction as the motor shaft 3 can be arranged along the outer peripheral surface of the gear box 4, and the wire harness can be laid out with a slight gap. Moreover, the electric motor 2 is usually installed in a narrow space because of the vehicle body arrangement. Therefore, in the above embodiment, since the wire harness 6 is pulled out from the electric motor 2 to the gear box 4 side, it is easy to wire the thick wire harness 6, and the gap formed by the gear box 4 is effectively utilized. And the wire harness 6 can be attached or detached easily. Further, the connector or grommet eliminates excessive protrusions, resulting in a compact configuration. Therefore, the space around the device can be used effectively, and the layout of the device is improved.

  FIG. 3 is a cross-sectional view showing a state in which a part of the electric motor used in the electric power steering apparatus according to the second embodiment of the present invention is cut away. In the figure, a bracket 22 forming an output shaft side end surface is fastened to a substantially cylindrical motor case body 21 of the electric motor 2 by bolts 23.

  Further, the bracket 22 is formed with an insertion hole 25 for the motor shaft 24 in the center, and the motor shaft 24 is rotatably supported by a bearing 26 in the insertion hole 25. A commutator 27 is disposed around the motor shaft 24, and a brush is in contact with the surface of the commutator 27.

  The brush holder 28 for holding the brush is disposed inside the bracket 22 and is attached to the bracket 22 by a bolt 29. Further, a substantially cylindrical connector 30 is integrally formed with resin on the outer surface of the brush holder 28 so as to protrude in substantially the same direction as the motor shaft 24. Further, in the connector portion 30, the connecting pin 7 for connecting to the wire harness 31 is formed so as to protrude in substantially the same direction as the motor shaft 24. Here, the connecting pin 7 may be integrally formed with the connector 30 and resin. In the electric motor 2, an O-ring 33 is provided between the bracket 22 and the brush holder 28, thereby being completely sealed.

  Therefore, the connector 30 of the brush holder 28 and the connecting pin 7 formed in the connector 30 are structured to extend in substantially the same direction with respect to the motor shaft 24, that is, in substantially the same direction. In addition, the molding die has a simple structure as compared with the case where the motor shaft 24 is molded in the radial direction. As a result, the manufacturing cost is reduced and the reliability is improved.

  Further, when the wire harness 31 is pulled out in the same direction as the motor shaft 24 on the gear box 4 side, when the wire harness 31 is attached / detached, a sufficient space is provided radially outside the motor shaft 24. Even if it does not exist, the wire harness 31 can be easily pulled out using the gap of the shape of the gear box 4 or the like. Therefore, the space around the electric motor 2 can be used effectively, and the layout is improved. Further, by integrally molding the motor bracket 22 and the gear box 4, the structure can be easily reduced and the space can be reduced.

  FIG. 4 shows a third embodiment of the present invention. A motor case 40 of the electric motor 2 is formed by integrally forming a yoke 41, a magnet holder 42, and a brush holder 43. The electric motor 2 includes a commutator 45 on the end surface of the rotor 44 on the side opposite to the output shaft (left side in FIG. 4), and the motor case 40 includes an output shaft side (right side in FIG. 4) and a counter output shaft side (left side in FIG. 4). The base portions 40A and 40B that respectively form end surfaces of the base portion 40C, and the cylindrical portion 40C that is connected to the magnet holder 42 from the outer edge of the base portion 40A.

  A connector 46 for connecting the wire harness 6 is formed on the base portion 40 </ b> A on the output shaft side of the motor case 40. A spring 47 and a brush 48 are accommodated in the brush holder 43, and the spring 47 biases the brush 48 axially toward the commutator 45 on the end face of the rotor 44.

  In general, a large amount of noise is generated in the current flowing through the wire harness 6 due to the discharge from the brush 48. Therefore, in the third embodiment, the connector 46 is formed so as to protrude from the motor case 40 to the side opposite to the installation position of the brush 48, that is, from the motor case 40 to the gear box side. As a result, it is possible to reduce the influence of noise caused by brush discharge on the wire harness 6.

  FIG. 5 shows a fourth embodiment of the present invention, in which the electric motor 2 is fixed to a gear box 4 as a speed reduction mechanism arranged on the output shaft side (left side in FIG. 5). The connector 5 is provided and is connected to the connector on the wire harness 6 side. Further, the gear box 4 is provided with a sensor housing 101, the upper surface of which is covered by a sensor cover 102 and fixed by four bolts 103 to seal the inside of the sensor housing 101.

As shown in enlarged detail in FIG. 6, a bracket 104 having an L-shaped cross section extends upward on the sensor cover 102, and the bracket 104 is fastened together with a bolt 103 at the lower end. It is fixed to. On the other hand, a tie wrap (registered trademark) 105 is attached to the upper end of the bracket 104, and a fixing portion 106 of the wire harness 6 positioned on the extension line in the pull-out direction from the connector 5 is configured. As a result, the wire harness 6 is pulled out from the connector 5 and arranged so as to be in the same direction as the motor shaft. Reference numeral 107 denotes a tube 107 that encloses the wire harness 6.

Accordingly, since the wire harness 6 is fixed by the tie wrap (registered trademark) 105, the mounting rigidity of the wire harness 6 on the gear box 4 side is increased, and an operator mistakenly attaches the electric power steering device to the vehicle body. Even if vibration or impact is generated during grabbing, carrying or traveling, the wire harness 6 is not subjected to large tension or impact. As a result, stress concentration due to high tension or impact of the wire harness 6 does not occur in the connector 5, and failure due to breakage does not occur, so that foreign matters such as water and dust do not enter the motor, and the durability of the device Improves.

  In the above embodiment, the brush motor has been described as an example. However, the present invention is not limited to this. For example, even when applied to a brushless motor, the same operations and effects as the above embodiment can be obtained.

1 is a schematic perspective view of an electric motor mounting structure showing a first embodiment of an electric power steering apparatus according to the present invention. FIG. 2 is an end view of the motor case viewed from the direction of line AA in FIG. 1. It is sectional drawing which showed 2nd Example of this invention and fractured | ruptured a part of electric motor. It is sectional drawing which showed 3rd Example of this invention and fractured | ruptured a part of electric motor. It is a schematic perspective view which shows 4th Example of this invention and shows the drawer structure of a wire harness. (A) is a figure explaining a mode that a wire harness is fixed to a bracket, (b) is a figure explaining the mode of the fixing | fixed part by a tie wrap (trademark) . It is a schematic explanatory drawing which shows the state by which the electric power steering device was mounted in the vehicle body. It is a schematic side view which shows the attachment structure of the conventional electric motor. It is sectional drawing which shows the internal structure of the conventional electric motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pinion shaft 2 Electric motor 3 Motor shaft 4 Gear box 5 Connector 6 Wire harness 7 Connecting pin 21 Motor case main body 22 Bracket 24 Motor shaft 28 Brush holder 30 Connector 31 Wire harness 40 Motor case 43 Brush holder 44 Rotor 46 Connector 48 Brush 101 Sensor housing 104 Bracket 105 Tie wrap (registered trademark)
106 fixed part

Claims (4)

In the electric power steering apparatus provided with a motor in the gear box and assisting the steering shaft via the reduction gear in the gear box by driving the motor,
The motor bracket is provided with a wire harness lead-out portion, the wire harness is pulled out from the lead-out portion to the reduction gear side, and the wire harness pull-out direction is substantially the same as the motor shaft .
The gear box has a worm storage portion for storing the worm of the reduction gear, a worm wheel storage portion for storing the worm wheel of the reduction gear, and a sensor storage portion formed on a side surface of the worm wheel storage portion. And
A fixing portion for the wire harness drawn from the lead-out portion is provided in a space formed by a step between the worm storage portion and the sensor storage portion and within the outer diameter range of the bracket; and
The electric power steering apparatus according to claim 1, wherein the fixing portion is disposed on an extension line in the drawing direction of the wire harness extending from the drawing portion . The fixing unit is made from the harness fixing bracket, the bracket is fixed to the sensor cover of the sensor housing provided in the gearbox at one end, claim which is adapted to secure the wire harness at the other end portion the electric power steering apparatus according to 1. A brush supported by a brush holder is disposed at a counter output shaft side end portion in the motor case of the motor , and
The drawer section, an electric power steering apparatus according to claim 1 or 2 is disposed on the output shaft side end opposite a is within the motor case of the brush. The bracket is formed integrally with the gear box, the wire harness is provided in the gear box, and the drawing direction of the wire harness is on the reduction gear side, and is substantially the same direction as the motor shaft. The electric power steering apparatus according to any one of claims 1 to 3 .

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