JP2013224114A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance belt tension adjusting accuracy.SOLUTION: An electric power steering device 100 is constituted so as to perform a steering assist by transmitting torque of a driving pulley 31 coaxially joined to a rotary shaft 21 of an electric motor via a belt 33 to a driven pulley 32 coaxially joint to a rotary member 12 of the steering device. The electric power steering device 100 includes a screw mechanism 50 as a guide means X for relatively moving a driving pulley support housing (22) and a driven pulley support housing (14). The screw mechanism 50 is set so that its axis L2 inclines by a predetermined quantity θ to the rotational axis L1 of the driving pulley 31, and a center distance S of both pulleys increases by screwing-in of its screw (53), and both housings 14 and 22 approach in the rotational axis (L1) direction.

Description

  The present invention transmits the rotational force of an electric power steering device, in particular, a driving pulley that is coaxially coupled to a rotating shaft of an electric motor, to a driven pulley that is coupled to a rotating member of the steering device via a belt. The present invention relates to an electric power steering apparatus configured to perform steering assist.

  This type of electric power steering apparatus is disclosed, for example, in Patent Document 1 below. In the electric power steering apparatus described in Patent Document 1 below, a drive pulley support housing that supports the drive pulley, a driven pulley support housing that supports the driven pulley, the drive pulley support housing, and the driven pulley support A belt tension adjusting mechanism capable of adjusting the tension of the belt by adjusting the distance between the centers of the two pulleys by relatively moving the housing.

JP 2003-220959 A

  In the electric power steering apparatus described in FIG. 5 and FIG. 6 of the above-mentioned Patent Document 1, the belt tension adjusting mechanism connects the drive pulley support housing and the driven pulley support housing with a distance between the centers of the two pulleys. A screw mechanism is included as guide means for relative movement in a changeable direction (direction substantially orthogonal to the rotation axis of the drive pulley). For this reason, it is possible to change the distance between the centers of both pulleys and adjust the belt tension by relatively moving both housings with the above-described screw mechanism.

  By the way, in the electric power steering apparatus disclosed in Patent Document 1, the axis of the screw mechanism extends in a direction substantially orthogonal to the rotational axis of the drive pulley. For this reason, screwing in with this screw mechanism can increase the distance between the centers of both pulleys, but cannot move both housings in the direction of the rotational axis of the drive pulley. Therefore, after adjusting the tension of the belt, if both housings are connected with a connecting bolt in the direction of the rotation axis of the drive pulley in order to maintain the state, both housings are connected to a minute gap (for example, screw of the screw mechanism). And a clearance with the insertion hole through which it is inserted), and the relative movement in the direction of the rotation axis of the drive pulley may cause a change in the center-to-center distance between both pulleys, which may change the belt tension. .

  Such a problem becomes prominent when a seal member (for waterproofing and dustproofing) that can be deformed in the rotational axis direction of the driving pulley is interposed between the driving pulley supporting housing and the driven pulley supporting housing. appear. In this case, when adjusting the belt tension by assembling both housings (when adjusting the belt tension), only the belt tension adjustment direction is required to move the drive pulley support housing relative to the driven pulley support housing. In addition, it is necessary to apply a force also in the direction in which the seal member is deformed between the two housings.

  For this reason, for example, when the belt tension adjustment of the electric power steering apparatus is performed manually, the two housings are relatively moved in the axial direction of the drive pulley, and the seal member is deformed between the two housings. , Both housings must be moved relative to each other in the radial direction of the drive pulley to adjust the belt tension, which is time-consuming and mechanically performed using equipment. Is complicated and expensive.

The present invention has been made to solve the above problems,
An electric motor configured to perform steering assist by transmitting, via a belt, the rotational force of a driving pulley coupled coaxially with the rotating shaft of the electric motor to a driven pulley coupled to a rotating member of the steering device. A power steering device,
A drive pulley support housing that supports the drive pulley, a driven pulley support housing that supports the driven pulley, and a relative movement of the drive pulley support housing and the driven pulley support housing to adjust the distance between the centers of the two pulleys. A belt tension adjusting mechanism capable of adjusting the tension of the belt by
The belt tension adjusting mechanism includes a screw mechanism as guide means for relatively moving the two housings. In this screw mechanism, the axis thereof is inclined by a predetermined amount with respect to the rotation axis of the drive pulley, and the screw The distance between the centers of the two pulleys is increased by screwing in and the two housings are set so as to be close to each other in the rotational axis direction.

  In the electric power steering apparatus according to the present invention, the axis of the screw mechanism is inclined by a predetermined amount with respect to the rotational axis of the drive pulley, and the screw-in of the screw of the screw mechanism increases the distance between the centers of the two pulleys. The housing is set so as to be close in the rotation axis direction. For this reason, if a screw (for example, a bolt) of a screw mechanism is rotated and screwed in, the distance between the centers of both pulleys can be increased to increase the belt tension, and both housings can be moved in the direction of the rotation axis. And can be joined to each other.

  Therefore, after that (after adjusting the belt tension), both housings are connected in the direction of the rotation axis of the drive pulley even if the two housings are connected by the connecting bolt in the direction of the rotation axis of the drive pulley. Almost no relative movement. For this reason, even if the state (the state after adjusting the belt tension) is maintained by the connecting bolt, the distance between the centers of both pulleys hardly changes and the belt tension is hardly changed.

  The above-described effects can be achieved even when a seal member (for waterproofing and dustproofing) that can be deformed in the rotational axis direction of the drive pulley is interposed between the drive pulley support housing and the driven pulley support housing. It is obtained similarly. As a result, the tension of the belt is adjusted by rotating the screw (for example, a bolt) in the screw mechanism, and the housing is compressed by deformation so that the seal member is crushed between the two housings. Coupled with high accuracy in the axial direction. For this reason, when the belt tension adjustment of the electric power steering apparatus is performed manually, it is possible to simplify (simplify) the workability, and when performing mechanically using equipment. The equipment specifications are simplified and inexpensive.

  In carrying out the above-described embodiment of the present invention (implementing a seal member between both housings), the seal member is accommodated in a seal groove formed in either one of the two housings, and is in the direction of the rotation axis. It can be elastically deformed, and a part of the driving pulley support housing and a part of the driven pulley support housing can be joined in the direction of the rotation axis. In this case, after adjusting the belt tension, even if the two housings are connected by the connecting bolt in the direction of the rotation axis of the drive pulley, the two housings do not move relative to each other in the direction of the rotation axis of the drive pulley. For this reason, even if the state (the state after adjusting the belt tension) is maintained by the connecting bolt, the distance between the centers of both pulleys does not change, and the belt tension does not change. Therefore, in this case, the accuracy of belt tension adjustment is improved.

1 is a front view schematically showing an embodiment of an electric power steering apparatus according to the present invention. It is a partially broken front view of the electric power steering device shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 schematically show an embodiment of an electric power steering apparatus according to the present invention. In the electric power steering apparatus 100, a rack shaft 11 (ball screw shaft) arranged in the vehicle width direction is provided. On the other hand, the rotating shaft 21 of the electric motor 20 is arranged in parallel. The electric power steering apparatus 100 includes a rack type steering apparatus 10 and an electric motor 20, and the rotational force of the drive pulley 31 (coaxially connected to the rotating shaft 21 of the electric motor 20 so that torque can be transmitted). (Rotational force) is transmitted via a toothed belt 33 to a driven pulley 32 that is coaxially coupled to a ball nut 12 that is a rotating member of the steering device 10 so as to be able to transmit torque, so that steering assist is performed. It is configured. The driven pulley 32 is integrally connected by a connecting nut 34 while being fitted to the outer periphery of the ball nut 12.

  The rack-type steering device 10 is known per se, and a rack shaft 11 connected to a steering wheel (not shown) via a pinion shaft (not shown), a steering shaft (not shown), etc. The housing 14 is supported so as to be movable in the vehicle width direction. Further, in this steering device 10, the ball nut 12 is assembled to the steering housing 14 of the steering device 10 via a bearing 13 so as to be rotatable and immovable in the axial direction.

  The ball nut 12 and the bearing 13 are assembled to the ball nut 12 to fix the inner ring 13a of the bearing 13 to the ball nut 12, and the steering housing 14 is assembled to the outer ring 13b of the bearing 13 to the steering housing 14. The vehicle is positioned and fixed in the vehicle width direction with respect to the steering housing 14 by a fixing nut 16 that is fixed to the steering housing 14. The ball nut 12 is composed of two members 12a and 12b and is integrally connected by a connecting nut 12c.

  The steering housing 14 includes a left portion 14A and a right portion 14B shown in the drawing, which are integrally connected by a plurality of connecting bolts 14C (see FIG. 1). In addition, a detachable lid 14D is assembled to the left portion 14A shown in the figure by three screws 14E. The lid 14D is removed when the tension of the belt 33 is inspected, and is configured such that a detection unit (not shown) of the inspection device is inserted through an opening (not shown) that is closed by this. Note that a fitting step (see FIG. 1) is formed at the joint between the illustrated left portion 14A and the illustrated right portion 14B, and sealing performance is ensured without using a seal member.

  The electric motor 20 is configured to be driven according to a steering torque transmitted from the steering wheel to the steering shaft. For this reason, the rotation of the rotating shaft 21 is transmitted to the ball nut 12 via the driving pulley 31, the belt 33, and the driven pulley 32, and is used as the axial driving force (assist force) of the rack shaft 11, so that the steering assist is performed. Done. The rotating shaft 21 is rotatably mounted on the motor housing 22 of the electric motor 20.

  By the way, in this embodiment, a drive pulley support housing that rotatably supports the drive pulley 31 together with the rotary shaft 21, that is, a motor pulley 22 and a driven pulley support that rotatably supports the driven pulley 32 together with the ball nut 12 and the like. The housing, that is, the steering housing 14 is guided by the guide means X so as to be relatively movable, and the relative movement is restricted by a plurality of bolts 61 (see FIG. 1) as restricting means. A seal member 71 (rubber O-ring) that is elastically deformable in the direction of the rotation axis (L1) of the drive pulley 31 is interposed between the motor housing 22 and the steering housing 14.

  The guide means X is a main part of the belt tension adjusting mechanism, and guides the motor housing 22 in the illustrated vertical direction with respect to the illustrated right portion 14B of the steering housing 14, and includes a screw mechanism 50. . The screw mechanism 50 includes a long hole 51 provided in the inclined wall 14a formed in the illustrated right portion 14A of the steering housing 14 and extending in the inclined direction of the inclined wall 14a, and a screw hole provided in the upper left end of the motor housing 22 in the drawing. 52 and a bolt 53 to be screwed into the screw hole 52 through the long hole 51. The long hole 51 is configured to be blocked by the head of the bolt 53.

  The axis L2 of the screw mechanism 50 is inclined by a predetermined amount θ with respect to the rotation axis L1 of the drive pulley 31 (rotation shaft 21), and the bolts 53 are screwed into the screw holes 52, so The center-to-center distance S is increased, and both the housings 14 and 22 are close to each other in the rotation axis (L1) direction so that the seal member 71 is compressed and deformed. The inclined wall 14 a of the steering housing 14 is formed so as to be substantially orthogonal to the axis L <b> 2 of the screw mechanism 50.

  Each bolt 61 is for integrally connecting the housings 14 and 22 in the direction of the rotation axis (L1) of the drive pulley 31 in order to maintain the state after adjusting the tension of the belt 33. Each bolt 61 is disposed so that its axis is parallel to the rotation axis L1 of the drive pulley 31, and is provided on the right portion 14B of the steering housing 14 and extends in the vertical direction of the drawing. It is configured to be screwed into a screw hole (not shown) provided in the flange portion of the motor housing 22 through a hole (not shown).

  The seal member 71 is provided between the housings 14 and 22 for waterproofing and dustproofing. The seal member 71 is accommodated in a seal groove 72 formed in the right portion 14B of the steering housing 14 in the figure. Can be elastically deformed in the direction of the rotation axis (L1) of the drive pulley 31. For this reason, a part (annular flange part) of the motor housing 22 and a part (annular part) of the steering housing 14 can be directly joined in the direction of the rotation axis (L1) of the drive pulley 31.

  In the electric power steering apparatus 100 of the present embodiment configured as described above, the lid 14D is removed from the steering housing 14, and the bolts 53 are rotated by the screw mechanism 50 while the bolts 61 are loosened. When screwed, the motor housing 22 is moved upward and left in the drawing with respect to the steering housing 14, and the center-to-center distance S between the pulleys 31 and 32 can be increased to increase the tension of the belt 33. At the same time, the two housings 14 and 22 can be brought close to each other in the direction of the rotation axis (L1) and directly joined to each other. The tension of the belt 33 is measured by an inspection device (not shown) through an opening (not shown) that is opened by removing the lid 14D.

  Therefore, after that (after adjusting the tension of the belt 33), even if both the housings 14 and 22 are integrally connected by the respective bolts 61 in order to maintain the state, both the housings 14 and 22 are still connected to the drive pulley 31. No relative movement in the direction of the rotation axis (L1). For this reason, even if the state (the state after the belt tension adjustment) is maintained by each bolt 61, the distance S between the centers of the pulleys 31 and 32 does not change, and the tension of the belt 33 does not change. Is done. Therefore, in this case, the accuracy of belt tension adjustment is maintained with high accuracy. The lid 14D is assembled to the steering housing 14 after adjusting the belt tension.

  In the electric power steering apparatus 100 of the above-described embodiment, as shown in FIG. 2, the center of the rack shaft 11 (axis L3), the rotation axis L1 of the drive pulley 31, and the axis L2 of the screw mechanism 50 are arranged on the same plane. However, it is also possible to configure and implement such that they are not arranged on the same plane. In any configuration, in the screw mechanism (50), the axis (L2) thereof is inclined by a predetermined amount with respect to the rotation axis (L1) of the drive pulley, and the distance between the centers of the two pulleys (S ) And the two housings may be set so as to be close to each other in the direction of the rotation axis (L1).

  Further, in the electric power steering apparatus 100 of the above-described embodiment, the screw mechanism 50 includes the long hole 51, the screw hole 52, and the bolt 53, and the bolt 53 extends along the long hole 51 when adjusting the tension of the belt 33. Although it implemented so that it might move, it replaced with the above-mentioned long hole 51, and while adopting the insertion hole which a bolt (53) can tilt, it can tilt with respect to a motor housing (22) instead of the screw hole 52 It is also possible to implement the present invention by using a nut to which the bolt (53) can be screwed.

  In the electric power steering apparatus 100 of the above-described embodiment, a seal member 71 (rubber O-ring) that is elastically deformable in the direction of the rotation axis (L1) of the drive pulley 31 is provided between the housings 14 and 22. Although implemented by interposing, the configuration of the sealing member interposed between the housings 14 and 22 can be changed as appropriate, and may be, for example, a plate shape, and is limited to the configuration of the above embodiment. It is not a thing. Moreover, when implementing this invention, it is also possible to implement without interposing a sealing member between both housings (14, 22).

  In the above-described embodiment, the present invention is applied to the electric power steering device in which the electric motor is disposed in parallel with the rack shaft disposed in the vehicle width direction. Also, various electric power steering devices (for example, an electric power steering device in which an electric motor is arranged in parallel with respect to a steering shaft arranged in the vehicle front-rear direction) are implemented in the same manner or appropriately modified. Is possible.

DESCRIPTION OF SYMBOLS 10 ... Steering device, 11 ... Rack shaft (ball screw shaft), 12 ... Ball nut (rotating member), 13 ... Bearing, 14 ... Steering housing (driven pulley support housing), 20 ... Electric motor, 21 ... Rotating shaft, 22 ... motor housing (drive pulley support housing), 31 ... drive pulley, 32 ... driven pulley, 33 ... belt, X ... guide means (main part of belt tension adjusting mechanism), 50 ... screw mechanism, 51 ... long hole, 52 ... Screw hole, 53 ... bolt (screw), 61 ... bolt, 71 ... seal member, 72 ... seal groove, L1 ... rotation axis, L2 ... axis of screw mechanism, 100 ... electric power steering device

Claims (3)

An electric motor configured to perform steering assist by transmitting, via a belt, the rotational force of a driving pulley coupled coaxially with the rotating shaft of the electric motor to a driven pulley coupled to a rotating member of the steering device. A power steering device,
A drive pulley support housing that supports the drive pulley, a driven pulley support housing that supports the driven pulley, and a relative movement of the drive pulley support housing and the driven pulley support housing to adjust the distance between the centers of the two pulleys. A belt tension adjusting mechanism capable of adjusting the tension of the belt by
The belt tension adjusting mechanism includes a screw mechanism as guide means for relatively moving the two housings. In this screw mechanism, the axis thereof is inclined by a predetermined amount with respect to the rotation axis of the drive pulley, and the screw The electric power steering apparatus is characterized in that the distance between the centers of the two pulleys is increased by screwing in and the two housings are set close to each other in the rotational axis direction. The electric power steering apparatus according to claim 1, wherein
An electric power steering apparatus characterized in that a seal member that is deformable in the direction of the rotation axis is interposed between the housings. The electric power steering apparatus according to claim 2,
The seal member is accommodated in a seal groove formed in one of the two housings and is elastically deformable in the direction of the rotation axis, and a part of the drive pulley support housing and the driven pulley support housing A part of the electric power steering device can be joined in the direction of the rotation axis.

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