JP2002225734A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device allowing an easy and rapid backlash adjustment between a first bevel gear and a second bevel gear meshed with each other in a crossing state of each axis line. SOLUTION: In this power steering device, a support shaft 1 provided with the first bevel gear 2 at the tip is rotatably supported by a retention member 8 via a rolling bearing 12. The relative position of the retention member 8 in the support shaft axial direction relatively to a support housing H1 can be adjusted by a retention member position adjustment mechanism 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for obtaining a steering assist force for a vehicle by an electric motor.

[0002]

2. Description of the Related Art Conventionally, as the electric power steering device, the rotation of an electric motor is controlled by a first bevel gear connected to an output shaft thereof via a support shaft, and a first bevel gear connected to the first bevel gear. For example, through a second bevel gear meshed with the axes intersecting at an acute angle, the shaft is transmitted to a rotating body surrounding the rack shaft, and the rotational motion of the rotating body is transmitted between the rotating body and the rack shaft. A linear motion of the rack shaft can be converted by a ball screw provided therebetween, and the electric motor is rotated in response to the rotation of the steering wheel (handle) to rotate the steered wheel connected to the rack shaft. There has been provided one that assists a manual steering force for steering (for example, see Japanese Patent Application Laid-Open No. 8-207796).

However, in the above-described conventional electric power steering apparatus, backlash may occur at a portion where the first and second bevel gears mesh with each other due to processing accuracy and assembly accuracy of the first and second bevel gears. When this backlash occurs, a so-called rattling sound is generated when the steering wheel is steered, and this leaks into the vehicle and may cause discomfort to the driver or the passenger. Therefore, at the time of assembling the apparatus, a shim is arranged on the mating surface between the spindle and the spindle housing accommodating the first bevel gear and the electric motor, and the spindle and the first bevel are arranged together with the output shaft of the electric motor. By integrally moving the gears in the axial direction, the engagement of the first bevel gear with the second bevel gear is adjusted so that the backlash does not occur.

[0004]

However, in the above-mentioned backlash adjustment work, it is usually impossible to properly engage both bevel gears with one shim adjustment, and it is necessary to repeat the shim adjustment many times. is there. Moreover, it is necessary to attach and detach the electric motor to and from the spindle housing every time the shim is adjusted. For this reason, there is a problem that the adjustment of the backlash is complicated and takes much time.

[0005] Even if the apparatus is adjusted so as not to cause backlash at the time of assembling the apparatus as described above, backlash occurs because the tooth surface of each bevel gear is worn due to long-term use of the apparatus. It is difficult to avoid. For this reason, there has been a problem that complicated maintenance is required, for example, it is necessary to disassemble the electric power steering apparatus periodically to perform backlash adjustment.

Further, if the amount of movement of the first bevel gear with respect to the second bevel gear becomes unnecessarily large due to the shim adjustment, the mesh point of the two bevel gears greatly deviates from a preset mesh point, and There is also a problem that the power transmission efficiency between the gears is reduced. The present invention has been made in view of the above problems, and has as its object to provide an electric power steering device capable of easily and quickly adjusting backlash. Another object of the present invention is to provide an electric power steering device capable of preventing backlash from occurring for a long period of time. A further object of the present invention is to provide an electric power steering device capable of preventing the point of engagement between the first bevel gear and the second bevel gear from being largely shifted due to the adjustment of the backlash.

[0007]

An electric power steering apparatus according to the present invention for achieving the above object is provided with a support shaft connected to an output shaft of an electric motor so as to be integrally rotatable, and a tip end of the support shaft. A first bevel gear, a support housing housing the support shaft and the first bevel gear, a rack shaft for turning steered wheels by linear movement, and a rack housing for supporting the rack shaft so as to be linearly movable. A second bevel gear meshed with the first bevel gear with their axes intersecting with each other, and the second bevel gear rotatably supported by the housing in a state surrounding the rack shaft, A rotating body to which a bevel gear is attached; and a ball screw configured between the rotating body and the rack shaft. The rotation of the electric motor is controlled by the support shaft, the first bevel gear, and the second bevel gear. Transmit to rotating body via gear The electric power steering device which assists manual steering force for steering the steered wheels by linearly moving the rack by means of: A holding member that rotatably holds via a bearing, and a holding member position adjusting mechanism that adjusts a relative position of the holding member with respect to the spindle housing in a spindle axis direction are provided (claim 1). .

According to the electric power steering apparatus having the above-described configuration, the relative position of the holding member with respect to the spindle housing in the spindle direction can be adjusted by the holding member position adjustment mechanism. At the same time, the first bevel gear can be moved in the axial direction. Therefore, the backlash between the first bevel gear and the second bevel gear can be adjusted without the need for the conventional shim adjustment.

In the electric power steering apparatus, a base end side of the support shaft is held by a holding member via the bearing, and a distal end side of the support shaft is movably held in a second bevel gear direction. At the same time, the distal end side of the support shaft may be urged toward the second bevel gear by an urging member (claim 2). In this case, even if each bevel gear is worn due to long-term use, the first bevel gear can be moved toward the second bevel gear by the urging member so as to follow the wear. For this reason, it is possible to prevent backlash from occurring at the meshing portion of both bevel gears due to the wear.

The electric power steering apparatus according to the second aspect of the present invention may further include a joint that connects the base end of the support shaft to the output shaft of the electric motor in a swingable manner. ). In this case, the first bevel gear can be smoothly moved to the second bevel gear by the joint.

The electric power steering apparatus includes a first housing that supports one end of the rotating body in a state where relative movement in the axial direction is allowed, and a second housing that supports the other end of the rotating body in the axial direction. The rack housing is divided into a second housing that supports the relative movement while being restricted, and the relative position of the first housing and the second housing in the rack axis direction can be adjusted by a housing position adjustment mechanism. (Claim 4). In this case, by adjusting the relative position of the first housing and the second housing in the rack axis direction by the housing position adjusting mechanism, the rotating body is moved together with the second bevel gear in the rack axis direction. By moving it, the mesh point of the two bevel gears can be adjusted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric power steering apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing one embodiment of the electric power steering apparatus of the present invention. The electric power steering device includes a housing H, an electric motor M attached to the housing H, a spindle 1 driven to rotate by the electric motor M, and a first shaft provided at the tip of the spindle 1. A bevel gear 2, a rack shaft 3 that passes through the inside of the housing H and steers steered wheels (not shown) by linear movement, a second bevel gear 4 meshed with the first bevel gear 2, A rotating body 5 rotatably supported by the housing H while surrounding the rack shaft 3, a ball screw 6 formed between the rotating body 5 and the rack shaft 3, and the support shaft 1 are held. A main part is constituted by the holding member 8 and a rack and pinion mechanism 9 for converting the rotation of the steered wheels into a linear motion of the rack shaft 3.

Referring to FIG. 2 as well, the housing H includes a spindle housing H1 on which the electric motor M is mounted and which accommodates the spindle 1 and the first bevel gear 2, and a rack shaft 3
And a rack housing H2 that accommodates the rotating body 5. The rack housing H2 is divided into a first housing H2a that supports the right end in the figure of the rotating body 5 and a second housing H2b that supports the left end in the figure of the rotating body 5. The first housing H2a is formed integrally with the spindle housing H1.
The electric motor M is fixed to the spindle housing H1 in a state where a front outer periphery M1 of the casing is fitted to an opening edge H1a of the spindle housing H1. The axis of the output shaft m of the electric motor M forms an acute angle with the axis of the rack shaft 3.

The first housing H2a and the second housing H2b are connected to each other so that a relative position in the axial direction can be adjusted by a housing position adjusting mechanism 10. The housing position adjusting mechanism 10 is provided with the first
Female screw 10 formed on the inner periphery of the left end of the housing H2a
a formed on the outer periphery of the right end of the second housing H2b;
The first housing H2a includes a male screw 10b screwed into the female screw 10a and a lock nut 10c screwed into the male screw 10b, and by adjusting the screwing depth of the male screw 10b into the female screw 10a. The relative position in the axial direction with respect to the second housing H2b can be adjusted. By tightening the lock nut 10c after this adjustment, it is possible to restrict the displacement of the relative position in the axial direction between the two.

The support shaft 1 has a proximal end 1a attached to an output shaft m of the electric motor M via a joint 1b so as to be integrally rotatable. The axis of the support shaft 1 is arranged on an extension of the axis of the output shaft m of the electric motor M. A part of the support shaft 1 is provided with a pair of rolling bearings 12.
And is rotatably held by the holding member 8 via.
The holding member 8 has a cylindrical shape, and its outer periphery is slidably fitted to the inner periphery of the spindle housing H1.
The holding member 8 and the spindle housing H1 can be relatively moved in the axial direction of the spindle 1 by the holding member position adjusting mechanism 11. The holding member position adjusting mechanism 11 includes a female screw 11 formed on the inner periphery on the right end side of the spindle housing H1.
a male screw 11b formed on the outer periphery on the right end side of the holding member 8 and screwed into the female screw 11a;
And a lock nut 11c screwed into the female screw 1b. By adjusting the screwing depth of the male screw 11b with respect to the female screw 11a, the relative position of the spindle housing H1 and the holding member 8 in the spindle direction is adjusted. By adjusting the lock nut 11c after this adjustment, it is possible to prevent the relative positions of the two from shifting in the axial direction.

The rack shaft 3 is held by the first housing H2a and the second housing H2b so as to be linearly movable in the axial direction. Both ends of the rack shaft 3 are connected to steered wheels (not shown) via ball joints 16, and the steered wheels can be steered by the linear movement. On the right end side of the rack shaft 3 in the drawing, a rack gear constituting a part of the rack and pinion mechanism 9 is formed.

The second bevel gear 4 is fitted and attached to the outer periphery of the rotating body 5, and in this state, rotation with respect to the rotating body 5 and movement in the axial direction are restricted. The axis of the second bevel gear 4 is aligned with the axis of the rack shaft 3, and the first bevel gear 2 is moved with respect to the teeth on the outer periphery of the second bevel gear 4.
It is movably engaged along its axial direction. The first bevel gear 2 is formed integrally with the tip of the support shaft 1.

The rotating body 5 is fitted on the outer periphery of the rack shaft 3 with a gap, and the right end thereof is a first rolling bearing 13.
And the left end is rotatably supported by the second housing H2b via the second rolling bearing 14.

The first rolling bearing 13 is formed of a ball bearing, and holds the rotating body 5 while allowing the rotating body 5 to move in the axial direction. Further, the second rolling bearing 14 is also constituted by a ball bearing, and its inner ring is also used by the rotating body 5. The relative movement in the axial direction between the outer ring 14a of the second rolling bearing 14 and the second housing H2b is restricted. Therefore, when the second housing H2b is moved in the axial direction of the rack shaft 3, the rotating body 5 can be moved in the axial direction.
Can be moved in the axial direction. Ball screw 6
It is configured between the rotating body 5 and the rack shaft 3, and converts the rotation of the rotating body 5 into a linear motion of the rack shaft 3.

The rack and pinion mechanism 9 includes a steering shaft 9a which is rotationally driven by a steering wheel (not shown).
And a pinion gear connected to the steering shaft 9a, and a rack gear meshed with the pinion gear and formed on the rack shaft 3. The rack shaft 3 is caused to linearly move as the steered wheels rotate. Can be. The rotation torque of the steering shaft 9a is detected by a torque sensor, and the electric motor M is driven by a power corresponding to the detected rotation torque to apply a steering assist force to the rack shaft 3.

In the electric power steering apparatus having the above structure, before the electric motor M is mounted on the spindle housing H1, the holding member 8 is rotated with the lock nut 11c of the holding member position adjusting mechanism 11 loosened. The holding member 8
Can be moved in the axial direction of the support shaft 1, whereby the support shaft 1 and the first bevel gear 2 can be moved in the axial direction. Can be adjusted. Accordingly, the backlash can be easily and quickly adjusted, in combination with the fact that the electric motor M does not need to be repeatedly attached to and detached from the spindle housing H1.

When it is necessary to adjust the first bevel gear 2 in the axial direction by a large amount when adjusting the backlash, the housing position adjusting mechanism 1 is used.
By moving the second bevel gear 4 along with the second housing H2b and the rotating body 5 in the axial direction, the amount of movement adjustment of the first bevel gear 2 can be reduced. For this reason, it is possible to prevent the power transmission efficiency from being reduced due to the fact that the meshing point between the first bevel gear 2 and the second bevel gear 4 is largely displaced from the preset meshing point. .

FIG. 3 is a sectional view of a main part showing another embodiment. In this embodiment, only the base end 1a side of the support shaft 1 is supported by the holding member 8 via one rolling bearing 12.
The tip end of the support shaft 1 is held so as to be movable (tilted) in the direction of the second bevel gear 4 and urged by the urging member 20 in the direction of the second bevel tooth 4. ing.

The holding member 8 for holding the base 1a side of the support shaft 1 is formed of a cylindrical body having a shorter overall length than the holding member 8 shown in FIG. The rolling bearing 12 interposed therebetween is constituted by a self-aligning bearing. Further, the distal end side of the support shaft 1 is rotatably held by a holding ring 21 via the other rolling bearing 12 formed of a ball bearing. The holding ring 21 is attached to the spindle housing H1 so as to be movable in a direction substantially orthogonal to the axis of the spindle 1. A clearance is provided between the inner periphery of the inner race of the rolling bearing 12 and the support shaft 1 to allow the support shaft 1 to move in the axial direction. Further, a base end 1a of the support shaft 1 is swingably connected to an output shaft m of the electric motor M via a joint 23. The joint 23 is formed of a cylindrical rubber coupling.

With the above configuration, the support shaft 1 can be easily tilted about the base end 1a with respect to the axis of the output shaft m. The inclination between the axis of the support shaft 1 and the axis of the rolling bearing 12 that supports the tip end thereof is allowed by the radial clearance and the thrust clearance of the rolling bearing 12 itself. The urging member 20 is formed of a compression coil spring, and is interposed between the cap 22 screwed into the spindle housing H1 and the holding ring 21 in a state of being elastically contracted.

According to this embodiment, the tip of the support shaft 1 can be tilted and constantly urged by the urging member 20 in the direction of the second bevel gear 4, so that the first bevel gear 2 Can be elastically pressed against the second bevel gear 4. Therefore, each bevel gear 2,
Even if the wheel 4 is worn, the first bevel gear 2 can be moved toward the second bevel gear 4 by following the wear. As a result, it is possible to prevent a backlash from occurring at a meshing portion between the bevel gears 2 and 4 for a long period of time. The electric power steering device of the present invention
The present invention can also be applied to an electric power steering apparatus of a type in which the axes of the first bevel gear 2 and the second bevel gear 4 intersect at right angles rather than at acute angles.

[0027]

As described above, according to the electric power steering apparatus of the first aspect, the relative position of the holding member with respect to the support shaft housing in the support shaft direction is adjusted by the holding member position adjusting mechanism. Since the axial position of the first bevel gear can be adjusted, the backlash between the first bevel gear and the second bevel gear can be adjusted without the need for conventional shim adjustment. Therefore, the backlash can be adjusted easily and quickly.

According to the electric power steering apparatus of the second aspect, even if each bevel gear is worn by use for a long period of time, the first bevel gear follows the wear by the urging member and the second bevel gear is made to follow. Since it can be moved to the gear side, it is possible to prevent backlash from occurring at the meshing portion of both bevel gears due to the wear. Therefore, occurrence of rattling noise can be prevented without requiring maintenance, and it is possible to prevent discomfort to a driver or a passenger due to the rattling noise for a long period of time. it can.

According to the electric power steering apparatus of the third aspect, the first bevel gear can be smoothly moved to the second bevel gear by the joint, so that the backlash is more reliably generated. Can be prevented.

According to the electric power steering apparatus of the fourth aspect, the second bevel gear and the rotating body can be moved in the rack axis direction by the housing position adjusting mechanism. The point of engagement with the second bevel gear can be adjusted. For this reason, it is possible to prevent the power transmission efficiency of both bevel gears from decreasing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electric power steering device according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the preceding figure.

FIG. 3 is an enlarged sectional view of a main part showing another embodiment.

[Explanation of symbols]

 Reference Signs List 1 support shaft 1a base end 2 first bevel gear 3 rack shaft 4 second bevel gear 5 rotating body 6 ball screw 8 holding member 9 rack and pinion mechanism 10 housing position adjusting mechanism 11 holding member position adjusting mechanism 12 rolling bearing 20 Urging member 21 holding ring 23 joint M electric motor m output shaft H housing H1 support shaft housing H2 rack housing H2a first housing H2b second housing

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masanori Arima 3-5-8 Minamisenba, Chuo-ku, Osaka Koyo Seiko Co., Ltd. F-term (reference) 3D033 CA04 CA05 JB03 3J062 AA07 AB22 AC07 BA25 BA26 CD23

Claims (4)

[Claims] 1. A supporting shaft connected to an output shaft of an electric motor so as to be integrally rotatable, a first bevel gear provided at a tip of the supporting shaft, and the supporting shaft and the first bevel gear are housed. A support shaft housing, a rack shaft that steers steered wheels by linear movement, a rack housing that supports the rack shaft so as to be able to linearly move, and a state in which the axes of the first bevel gear cross each other. A meshed second bevel gear, a rotating body rotatably supported by the housing in a state surrounding the rack shaft, and having the second bevel gear attached thereto, and between the rotating body and the rack shaft. The rack is moved linearly by transmitting the rotation of the electric motor to the rotating body via the support shaft, the first bevel gear, and the second bevel gear, Assists manual steering force to steer steering wheel In the dynamic power steering device, a holding member movably attached to the spindle housing in a spindle axis direction and rotatably holding the spindle via a bearing; and a spindle of the holding member with respect to the spindle housing. An electric power steering device comprising: a holding member position adjusting mechanism for adjusting a relative position in an axial direction. 2. A base end side of the support shaft is held by a holding member via the bearing, and a distal end side of the support shaft is movably held in a second bevel gear direction. 2. The electric power steering apparatus according to claim 1, wherein the distal end side of the electric power steering device is urged toward the second bevel gear by an urging member. 3. A joint for pivotally connecting a base end of a support shaft to an output shaft of the electric motor.
The electric power steering device according to claim 1. 4. A first housing for supporting one end of the rotating body in a state in which relative movement in the axial direction is permitted, and restricting a relative movement of the other end of the rotating body in the axial direction. The rack housing is divided into a second housing supported in a state, and a relative position of the first housing and the second housing in a rack axis direction can be adjusted by a housing position adjusting mechanism. 2. The electric power steering device according to 1.