JP2008174170A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of effectively shutting off operation sound generated by a speed-reduction mechanism in a gear box so as not to transmit it to a driver side. <P>SOLUTION: The electric power steering device is provided with: an electric motor for giving steering assistant force relative to a steering shaft connected to a steering wheel; the gear box storing the speed-reduction mechanism for transmitting the steering assistant force of the electric motor to the steering shaft; and a control unit for controlling driving of the electric motor. The control unit is arranged at a steering wheel side than the gear box. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electric power steering apparatus using an electric motor as a generation source of steering assist torque, and more particularly to improvement of a layout of a control unit (ECU) that controls driving of the electric motor.

  An electric power steering device mounted on a vehicle or the like drives an electric motor according to a steering torque applied via a steering wheel, and the rotation of the electric motor is transmitted to the steering mechanism via a speed reduction mechanism. Assisting the steering of the vehicle. The steering assist electric motor is electrically connected to a control unit including a CPU (including an MPU) and the drive is controlled by the control unit.

  FIG. 9 is a perspective view schematically showing a column portion of a conventional ECU-mounted electric power steering apparatus. In the figure, an electric power steering apparatus 101 includes a steering column 102 that rotatably supports a steering shaft (not shown), an electric motor 103 that applies a steering assist force to the steering shaft, and a drive current of the electric motor 103. And a control unit 104 for controlling the motor, and the electric motor 103 and the control unit 104 are of the column assist type mounted on the steering column 102 as a steering mechanism mounting member.

  At the base end portion of the steering column 102, a gear box 105 is provided that houses a speed reduction mechanism that transmits the steering assist force of the electric motor 103 to the steering shaft. The speed reduction mechanism housed in the gear box 105 includes a worm coupled to the drive shaft of the electric motor 103 and a worm wheel meshed with the worm and coupled to the steering shaft. It is configured to decelerate and transmit to the steering shaft.

  The control unit 104 is connected to a torque sensor or a vehicle speed sensor (not shown), and controls the drive current of the electric motor 103 in accordance with signals output from these various sensors.

  By the way, in the electric power steering apparatus 101 in which the electric motor 103 and the control unit 104 are integrally mounted on the steering column 102 as shown in FIG. is important.

  Therefore, conventionally, an ECU-mounted electric power steering apparatus having such a configuration has a layout layout of the electric motor 103 and the control unit 104 in order to add functions for improving layout performance and heat dissipation efficiency. Improvements were made.

  For example, in Japanese Patent Application No. 2005-201267, an L-shaped control unit formed along the side of a gear box is closely attached to the gear box in order to dissipate heat generated by the power module housed in the control unit. There is disclosed an electric power steering apparatus which is arranged so as to allow heat generated by the power module to escape to the gear box.

  Japanese Patent Application No. 2006-106069 discloses an electric power steering apparatus having a sound insulation structure for reducing noise of an electric motor transmitted to a driver seat and a passenger seat in a passenger compartment.

JP-A-11-011329

  In the conventional column assist type electric power steering device, there are few layouts to which the effect of improving the operation noise, which is an important issue, is added, and in particular, it is generated by the speed reduction mechanism (meshing portion between the worm and the worm wheel) in the gear box 105. Similarly to the sound emitted from the electric motor 103, the operation sound is transmitted to the driver side in the passenger compartment.

  However, the layout disclosed in Japanese Patent Application No. 2006-106069 is a sound insulation structure for the purpose of reducing the noise of the electric motor 103 transmitted to the driver side, and the operation sound generated by the speed reduction mechanism in the gear box 105 is reduced. It was not a layout to block. In the conventional mounting layout of a vehicle and an electric power steering device (for example, Patent Document 1), there are many structures in which an instrument panel reinforcement (strengthening member) passes on the driver side of the electric motor. Therefore, the structure disclosed in Japanese Patent Application No. 2006-106069 However, since the rain force passes to the driver side from the electric motor, a certain sound insulation effect of the electric motor was obtained by this rain force.

  In addition, there has been a control unit 104 attached so as to cover a part of the gear box 105 on the driver side (for example, Japanese Patent Application No. 2005-201267). In order to use the gear box 105 as a heat sink in order to release the heat of the module, the control unit 104 is brought into close contact with the gear box 105. In this structure, since the metal electric motor and the metal ECU are in contact, the case of the control unit 104 having rigidity lower than that of the gear box 105 housing is added to the gear box 105 as a vibration source. There was a possibility that the operating noise would be further deteriorated due to the vibration.

  Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to effectively block the operation sound generated by the speed reduction mechanism in the gear box from being transmitted to the driver side. An object is to provide an electric power steering apparatus.

  An object of the present invention is to provide an electric motor that applies a steering assist force to a steering shaft connected to a steering wheel, and a gear box that houses a reduction mechanism that transmits the steering assist force of the electric motor to the steering shaft. In the electric power steering apparatus comprising a control unit for controlling the driving of the electric motor, the control unit is achieved by being arranged closer to the steering wheel than the gear box.

  Moreover, the said objective is effectively achieved by the said control unit having been arrange | positioned close to the said gear box in the non-contact state.

  Moreover, the said objective is effectively achieved by the proximity | contact arrangement | positioning in which the said control unit contacted the said gear box via the elastic body.

  The object is effectively achieved by the control unit having a sound insulating plate extending from a part of the case surface facing the gear box toward the lower part of the bottom of the gear box.

  Moreover, the said objective is effectively achieved by the said control unit having a sound insulation board extended in the direction of the said electric motor along the case surface facing the said gear box.

  Moreover, the said objective is effectively achieved because the said sound insulation board has a plate-shaped sound-absorbing material in the surface facing the said gear box.

  Moreover, the said objective is effectively achieved by having a plate-shaped sound-absorbing material in the surface facing the said control unit and the said gear box.

  Moreover, the said objective is effectively achieved because the said sound-absorbing material was provided over the whole surface facing the said gear box.

  Further, the object is that the electric motor and the gear box are provided at a base end portion of a steering column that rotatably supports the steering shaft, and the control unit is fixed to the steering column. Effectively achieved.

  According to the electric power steering apparatus according to the present invention, the control unit for controlling the drive of the electric motor is arranged closer to the steering wheel side (driver side) than the gear box containing the speed reduction mechanism that transmits the steering assist force of the electric motor to the steering shaft. Arranged. As a result, it is possible to reduce the propagation of the operation sound generated by the speed reduction mechanism in the gear box to the driver side, so that it is possible to achieve both the freedom of layout and the effect of blocking the operation sound.

  In addition, by arranging the control unit close to the gear box in a non-contact state, it is possible to prevent the control unit from being excited with the vibration of the gear box, and to effectively generate the operating noise generated in the gear box. Can be blocked.

  Further, by arranging the control unit in close proximity to the gear box through an elastic sound absorbing material, in addition to the above effects, vibration generated in the gear box can be reduced by the principle of a dynamic damper.

  In addition, by providing a sound insulation plate extending from a part of the case surface of the control unit facing the gear box toward the bottom of the gear box, noise transmitted from the gear box to the bottom of the bottom can be blocked. In addition, by providing a sound insulating plate extending in the direction of the electric motor along the case surface of the control unit facing the gear box, noise transmitted from the electric motor to the driver side can be blocked. As a result, a sound insulation effect can be realized more effectively.

  Furthermore, by providing a plate-like sound absorbing material on the surface of the control unit and the sound insulation plate facing the gear box, it is possible to absorb the operating sound radiated from the gear box and the electric motor, and to reduce the noise in the electric power steering device. This can be further reduced.

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

  FIG. 1 is a mechanism diagram showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention. In the figure, the steering mechanism of the electric power steering apparatus 1 includes a steering shaft 3 that rotates in response to a steering operation of a steering wheel 2 attached to a tip portion, and a universal joint 4 on the other end side of the steering shaft 3. 5 and a rack and pinion mechanism 6 that converts the rotational motion of the steering shaft 2 into a linear motion of the rack shaft, and a tie rod 7 that transmits the motion of the rack shaft of the rack and pinion mechanism 6 to the steering wheel. It is composed of

  In addition, the column portion of the electric power steering apparatus 1 includes a torque sensor 8 that detects a steering torque input to the steering shaft 3 via the steering wheel 2 and a steering coupled to the steering shaft 3 via the speed reduction mechanism 9. An auxiliary electric motor 10 is provided.

  Driving of the electric motor 10 is controlled by a control unit (ECU) 11 equipped with a control circuit and the like. Electric power is supplied from the battery 12 to the control unit 11, and an ignition key signal is input from the ignition key 13. The control unit 11 calculates the steering assist command value I based on the steering torque value T detected by the torque sensor 8 and the vehicle speed V detected by the vehicle speed sensor 14, and the calculated steering assist command value is calculated. The drive current supplied to the electric motor 10 is controlled according to I.

[First Embodiment]
FIG. 2 is a perspective view schematically showing a column portion of the electric power steering apparatus according to the first embodiment of the present invention, and FIG. 3 is a schematic view of the column portion of the electric power steering apparatus according to the first embodiment. FIG.

  The steering shaft 3 described above is rotatably supported in a substantially cylindrical steering column 15 shown in FIG. In a gear box 16 provided at the base end of the steering column 15, a speed reduction is made up of a worm coupled to the drive shaft of the electric motor 10 and a worm wheel meshed with the worm and coupled to the steering shaft 3. A mechanism 9 is accommodated. The rotation of the electric motor 10 is decelerated via the speed reduction mechanism 9 and transmitted to the steering shaft 3.

  The electric motor 10 has a flange portion 10a formed at a boundary position between the main body portion and the drive shaft, and a mounting hole 17 is formed in the flange portion 10a. A fixing bolt as a detachable mechanical fixing means is inserted into the mounting hole 17 and fastened to a tap hole formed in the upper part of the gear box 16. Thereby, the electric motor 10 is fixed to the gear box 16.

  The control unit 11 that controls the drive current of the electric motor 10 is electrically connected to the electric motor 10 via the power harness 18. As shown in FIG. 3, the control unit 11 is disposed close to the steering wheel 2 from the gear box 16 in a non-contact state, and is fixed to the steering column 15 via a fixing bolt 19. In other words, the control unit 11 is arranged so as to block between the gear box 16 and the steering wheel 2. In general, the case of the control unit 11 is formed of a metal material having lower rigidity than that of the gear box 16, so that when the control unit 11 is placed in contact with the gear box 16 made of metal, the excitation force of the gear box 16 As a result, the case of the control unit 11 may vibrate and the noise may be further deteriorated. Therefore, in this embodiment, the control unit 11 is disposed at a position slightly away from the steering wheel 2 side of the gear box. With this arrangement structure, the sound emitted from the gear box 16 toward the steering wheel 2 side (driver side) is blocked by the control unit 11.

  Further, in the conventional ECU-mounted electric power steering apparatus 101 as shown in FIG. 9, there are many portions where the control unit 104 protrudes in the radial direction from the column cylindrical portion, but the electric power steering apparatus according to the present embodiment. 1, the control unit 11 can be mounted so as not to protrude from the column cylindrical portion in the radial direction as much as possible. Thus, the control unit 11 can be arranged to block the sound radiated from the meshing portion between the worm and the worm wheel, which is one of the problems of noise generated in the gear box 16.

  In addition, the sound absorbing material 20 is provided over the entire surface of the case facing the gear box 16 of the control unit 11, thereby further improving the sound insulation performance. The material of the sound absorbing material 20 is preferably a polyurethane-based material such as glass wool or urethane foam, which is excellent in sound absorbing effect, for example, and a composite material combining a plurality of materials having the sound absorbing effect described above may be used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  FIG. 4 is a perspective view schematically showing a column portion of the electric power steering apparatus according to the second embodiment of the present invention, and FIG. 5 is a schematic view of the column portion of the electric power steering apparatus according to the second embodiment. FIG. In the present embodiment, the same members as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the electric power steering apparatus 1A according to the present embodiment, the control unit 11A is disposed close to the steering wheel 2 side in a non-contact state from the gear box 16 as in the electric power steering apparatus 1 according to the first embodiment described above. The steering column 15 is fixed via a fixing bolt 19.

  A gear box lower sound insulating plate 21 extending from a case surface facing the gear box 16 toward a lower portion of the bottom of the gear box 16 is provided at the bottom of the control unit 11A, and a gear box is provided above the control unit 11A. An electric motor side sound insulation plate 22 extending in the direction of the electric motor 10 along the case surface facing 16 is provided. These sound insulating plates 21 and 22 are made of an aluminum-based material, and the operation sound of the speed reduction mechanism 9 radiated downward from the bottom of the gear box 16 and the electric motor 10 radiated in the direction of the steering shaft 2 from the side surface of the electric motor 10. Shut off the operation sound. A sound absorbing material 20A having a sound absorbing effect is provided over the entire surface of the sound insulating plates 21 and 22 and the surface of the control unit 11A facing the gear box 16.

  The power harness 18 is inserted into a harness hole 23 formed so as to penetrate the electric motor side sound insulation plate 21 and the sound absorbing material 20, and electrically connects the control unit 11A and the electric motor 10. . In FIG. 4, the power harnesses 18 for three phases are inserted into the separate harness holes 23, but the invention is not limited to this. For example, the power harnesses 18 for three phases are put together in one harness hole 23. It may be inserted.

  As described above, according to the electric power steering apparatus 1A according to the present embodiment, the control unit 11A is disposed close to the steering wheel 2 side in a non-contact manner from the gear box 16, and is disposed at the bottom of the control unit 11A. A gear box lower sound insulating plate 21 is provided, and an electric motor side sound insulating plate 22 is provided above the control unit 11A. As a result, the operational effect of the speed reduction mechanism 9 radiated downward from the bottom of the gear box 16 can be blocked by the gear box lower sound insulation plate 21 as well as the same effects as the first embodiment described above. In addition, since the operation sound of the electric motor 10 radiated in the direction of the steering shaft 2 from the side surface of the electric motor 10 can be blocked by the electric motor side sound insulation plate 22, the noise of the electric power steering device can be reduced. This can be achieved more effectively.

  In the present embodiment, a flat plate is attached as the electric motor side sound insulation plate 21, but the present invention is not limited to this, and for example, an arc plate formed in accordance with the shape of the electric motor 10 is used. In this case, a more effective sound insulation effect can be achieved.

[Third Embodiment]
FIG. 6 is a side view schematically showing a column portion of the electric power steering apparatus according to the third embodiment of the present invention. In the present embodiment, the same members as those in the first and second embodiments described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, the control unit 11B of the electric power steering apparatus 1B is disposed close to the gear box 16 in contact with the steering wheel 2 side via an elastic body 24. Thereby, not only the sound insulation effect similar to the first embodiment can be obtained, but also the control unit 11B can be used as the mass of the dynamic damper that reduces the vibration generated in the gear box 16.

[Fourth Embodiment]
FIG. 7 is a perspective view schematically showing a column portion of the electric power steering apparatus according to the fourth embodiment of the present invention. In the present embodiment, the same members as those in the first to third embodiments described above are denoted by the same reference numerals, and the description thereof is omitted. In addition, the power harness 18 that connects the electric motor 10 and the control unit 11C is not shown in order to simplify the description.

  In the figure, the ECU board 11a of the control unit 11C is directly fixed to a board mounting surface 25 formed on a part of the steering column 15C on the steering wheel 2 side from the gear box 16 so as to cover the ECU board 11a. A box-shaped ECU cover 11b is attached. Further, a sound absorbing material 20 is provided over the entire surface of the ECU cover 11b facing the gear box, as in the first embodiment.

  In the electric power steering apparatus 1C according to the present embodiment, the ECU board 11a of the control unit 11C is directly attached to the steering column 15C, but the ECU cover 11b that covers the ECU board 11a includes the gear box 16 and the steering wheel. Therefore, it is possible to obtain the same effect as that of the first embodiment and to improve the heat dissipation effect of the ECU board 11a.

[Fifth Embodiment]
FIG. 8A is a perspective view schematically showing a column portion of an electric power steering apparatus according to the fifth embodiment of the present invention, and FIG. 8B is an ECU of a control unit according to the fifth embodiment. It is explanatory drawing which shows the state in which the cover was attached schematically. In the present embodiment, the same members as those in the first to fourth embodiments described above are denoted by the same reference numerals, and the description thereof is omitted. In addition, the power harness 18 that connects the electric motor 10 and the control unit 11D is not shown in order to simplify the description.

  In the figure, an ECU board 11a of the control unit 11D is directly fixed to a board mounting surface 26 formed on the steering wheel 2 side of the gear box 16D, and a box-shaped ECU cover 11b is formed so as to cover the ECU board 11a. 'Is attached.

  The ECU cover 11b 'has a lower side surface extending in the opening direction so that the lower side of the gear box 16 can be covered when the ECU cover 11b' is attached. Thereby, not only the operation sound of the speed reduction mechanism 9 radiated in the direction of the steering wheel 2 from the gear box 16D but also the operation sound radiated downward from the bottom of the gear box 16D can be blocked.

  Further, in the electric power steering apparatus 1D according to the present embodiment, since the control unit 11D is directly attached to the gear box 16, the ECU cover 11b ′ is thick and highly rigid so as not to vibrate due to the excitation force of the speed reduction mechanism 9. It is made of material.

  With such a configuration, the electric power steering apparatus 1D according to the present embodiment can obtain the sound insulation effect similar to that of the first embodiment, the heat dissipation effect of the ECU board 11a, and the excitation force received by the speed reduction mechanism 9. The damping effect can be improved.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to this, In the range which does not deviate from the meaning, it can change suitably.

It is a mechanism figure showing a schematic structure of an electric power steering device concerning an embodiment of the present invention. It is a perspective view showing roughly the column part of the electric power steering device concerning a 1st embodiment of the present invention. It is a side view which shows roughly the column part of the electric power steering device concerning a 1st embodiment of the present invention. It is a perspective view showing roughly the column part of the electric power steering device concerning a 2nd embodiment of the present invention. It is a side view which shows roughly the column part of the electric power steering apparatus which concerns on 2nd Embodiment of this invention. It is a side view which shows roughly the column part of the electric power steering apparatus which concerns on 3rd Embodiment of this invention. It is a perspective view showing roughly the column part of the electric power steering device concerning a 4th embodiment of the present invention. (A) is a perspective view which shows roughly the column part of the electric power steering apparatus which concerns on 5th Embodiment of this invention, (b) is equipped with the ECU cover of the control unit which concerns on 5th Embodiment. FIG. It is a perspective view which shows schematically the column part of the conventional electric power steering device.

Explanation of symbols

1, 1A, 1B, 1C, 1D Electric power steering device 2 Steering wheel 3 Steering shaft 9 Reduction mechanism 10 Electric motors 11, 11A, 11B, 11C, 11D Control unit (ECU)
15, 15C Steering columns 16, 16D Gear box 20, 20A Sound absorbing material 21 Gear box lower sound insulating plate 22 Electric motor side sound insulating plate 24 Elastic body

Claims (9)

An electric motor for applying a steering assist force to a steering shaft connected to a steering wheel; a gear box containing a speed reduction mechanism for transmitting the steering assist force of the electric motor to the steering shaft; and driving the electric motor. An electric power steering device comprising a control unit for controlling,
The electric power steering apparatus, wherein the control unit is disposed closer to the steering wheel than the gear box.   The electric power steering apparatus according to claim 1, wherein the control unit is disposed close to the gear box in a non-contact state.   The electric power steering apparatus according to claim 1, wherein the control unit is disposed close to the gear box in contact with the gear box via an elastic body.   The electric power steering apparatus according to any one of claims 1 to 3, wherein the control unit includes a sound insulating plate extending from a part of a case surface facing the gear box toward a lower part of the bottom of the gear box.   The electric power steering apparatus according to any one of claims 1 to 4, wherein the control unit includes a sound insulating plate extending in a direction of the electric motor along a case surface facing the gear box.   The electric power steering apparatus according to claim 4 or 5, wherein the sound insulating plate has a plate-like sound absorbing material on a surface facing the gear box.   The electric power steering apparatus according to any one of claims 1 to 6, wherein the control unit includes a plate-like sound absorbing material on a surface facing the gear box.   The electric power steering apparatus according to claim 6 or 7, wherein the sound absorbing material is provided over the entire surface facing the gear box. The electric motor and the gear box are provided at a base end portion of a steering column that rotatably supports the steering shaft, and
The electric power steering apparatus according to any one of claims 1 to 8, wherein the control unit is fixed to the steering column.