JP4016604B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering apparatus that obtains a steering assist force of a vehicle by an electric motor.
[0002]
[Prior art]
Conventionally, as the electric power steering device, the rotation of the electric motor is performed by, for example, a first bevel gear connected to the output shaft via a support shaft, and an axis of the first bevel gear at an acute angle, for example. Via a second bevel gear meshed in an intersecting state, the rotation is transmitted to a rotating body surrounding the rack shaft, and the rotational movement of the rotating body is provided between the rotating body and the rack shaft. A ball screw serving as a rotational motion conversion mechanism can be converted into a linear motion of the rack shaft, and the electric motor is driven to rotate in response to the rotation of the steering wheel (handle), thereby turning the steered wheels connected to the rack shaft. A device that assists a manual steering force for turning is provided (see, for example, Japanese Patent Laid-Open No. Hei 8-207796).
[0003]
However, in the above-described conventional electric power steering device, backlash may occur at the meshing portion between the first and second bevel gears due to the processing accuracy and assembly accuracy of the first and second bevel gears. When the rush occurs, a so-called rattling noise is generated when the steering wheel is steered, which may leak into the vehicle and cause discomfort to the driver and passengers.
Therefore, when assembling the apparatus, a shim is disposed on the abutting surface of the cylindrical holding member that holds the support shaft and the support housing fitted with the support member, and the support shaft and the first bevel gear are arranged. By moving the shaft in the axial direction, the meshing state of the first bevel gear with the second bevel gear is adjusted so that the backlash does not occur.
[0004]
[Problems to be solved by the invention]
However, in the adjustment operation of the backlash, normally, both bevel gears cannot be properly meshed with one shim adjustment, and the shim adjustment needs to be repeated many times. Moreover, it is necessary to attach and detach the electric motor to and from the spindle housing every time shim adjustment is performed. For this reason, there is a problem that adjustment of backlash is complicated and time-consuming.
[0005]
Further, even if adjustment is made so that backlash does not occur when the device is assembled as described above, the tooth face of each bevel gear is worn by long-term use of the device, so that occurrence of backlash is avoided. It is difficult. For this reason, there has been a problem that complicated maintenance is required, for example, it is necessary to periodically disassemble the electric power steering device and perform backlash adjustment.
[0006]
Furthermore, when the amount of movement of the first bevel gear in the axial direction becomes larger than necessary due to the shim adjustment, the meshing point of both the bevel gears deviates greatly from the preset meshing point, and the power transmission between the two bevel gears There was also a problem that efficiency decreased.
The present invention has been made in view of the above problems, and can easily and quickly adjust the backlash, and can prevent the occurrence of backlash over a long period of time. It is an object of the present invention to provide an electric power steering device that can prevent the meshing points of the bevel gears from being greatly shifted with the adjustment of the lash.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an electric power steering apparatus according to the present invention includes a support shaft connected to an output shaft of an electric motor so as to be integrally rotatable, a first bevel gear provided at the tip of the support shaft, A supporting shaft housing that accommodates the supporting shaft, a rack shaft that steers the steered wheels by linear movement, a rack housing that supports the rack shaft so as to be linearly movable, and a mutual axis line with respect to the first bevel gear A second bevel gear meshed in an intersecting state, a rotating body rotatably supported by a rack housing in a state of surrounding the rack shaft, and the second bevel gear attached thereto; A rotary motion converting mechanism that converts the rotary motion into a linear motion of the rack shaft, and transmitting the rotation of the electric motor to the rotating body via the support shaft, the first bevel gear, and the second bevel gear. The rack is directly So moved, in the electric power steering device for assisting a manual steering force for steering the steered wheels,
A cylindrical holding member provided inside the spindle housing so as to be capable of eccentric rotation, attaching the electric motor to one end, and holding the spindle coaxially with an inner peripheral surface;
A spring that urges the holding member in a predetermined rotation direction and elastically presses the first bevel gear against the second bevel gear ;
The outer periphery of the lower end side of the holding member is rotatably fitted in a fitting hole formed in the spindle housing,
A flange-shaped first spring receiving portion protrudes from the axially intermediate portion of the holding member, and a diameter-expanding portion for attaching the electric motor is provided at one end, and faces the first spring receiving portion. The ring-shaped second spring receiving portion is rotatably arranged, and the spring is formed in a C shape and interposed between the first spring receiving portion and the second spring receiving portion, The second spring receiving portion is attached by a detent ring attached to the spindle housing in a state where one end of the spring is locked to the first spring receiving portion and the other end is locked to the second spring receiving portion. The rotation of the
The detent ring is screwed into the spindle housing, and its rotation is restricted by a lock nut, and the detent ring is fitted to the back surface of the second spring receiving portion via a friction member so as to be integrally rotatable. And
A base end portion of the support shaft, that has features that you have mounted for integral rotation to the output shaft of the electric motor.
[0008]
According to the electric power steering apparatus having the above-described configuration, the first bevel gear can be moved in the radial direction by rotating the holding member and decentering the first bevel gear. It can be made to contact / separate with respect to a 2nd bevel gear. For this reason, the backlash of the meshing part of both bevel gears can be adjusted only by adjusting the position of the holding member in the rotational direction. Further, when each bevel gear is worn by long-term use, the holding member is gradually rotated by the urging force of the spring, and the first bevel gear is moved to the second bevel gear side following the wear. be able to. For this reason, it is possible to prevent backlash from occurring at the meshing portion of both bevel gears due to the wear. Further, since the backlash is adjusted by moving the first bevel gear in the radial direction, there is no possibility that the preset mesh point is shifted in the axial direction.
[0009]
Further, in the electric power steering apparatus , a hook-shaped first spring receiving portion is protruded from the holding member, and the ring-shaped second spring receiving portion is rotated so as to face the first spring receiving portion. The spring is C-shaped and is interposed between the first spring receiving portion and the second spring receiving portion, and one end of the spring is located in the first spring receiving portion. in a state where the other end engaged with the respective said second spring receiving portion, you are restricted to rotation of the second spring receiving portion by detent ring.
Therefore , the spring can be easily arranged in a small space, and the holding member can be urged to rotate with a simple configuration. Further, the biasing force of the spring can be adjusted by rotating the second spring receiving portion in a state in which the backlash is adjusted by rotating the holding member.
[0010]
Furthermore, in the electric power steering device, screwing the detent ring shaft housing, along with being restricted by the lock nut the rotary friction member the detent ring on the back of the second spring receiving portion through that it has not integrally rotatable along.
Therefore , the second spring receiving portion can be rotationally adjusted via the friction member by loosening the lock nut and rotating the rotation prevention ring. Further, since the relative rotation between the second spring receiving portion and the rotation prevention ring is allowed, the rotational direction position of the second spring receiving portion with respect to the holding member can be set easily and appropriately.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments 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 cross-sectional view showing an embodiment of the electric power steering apparatus of the present invention. The electric power steering apparatus includes a housing H, an electric motor M attached to the housing H, a spindle 1 that is rotationally driven 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 is inserted through the inside of the housing H and steers a steered wheel (not shown) by linear movement, a second bevel gear 4 meshed with the first bevel gear 2, and A rotating body 5 rotatably supported by a housing H in a state of surrounding the rack shaft 3; a ball screw 6 as a rotational motion conversion mechanism configured between the rotating body 5 and the rack shaft 3; A main part is constituted by a cylindrical holding member 8 that holds the electric motor M and the support shaft 1 and a rack and pinion mechanism 9 that converts the rotation of the steering wheel into a linear motion of the rack shaft 3.
[0012]
Referring also to FIG. 2, the housing H includes a support shaft housing H <b> 1 that houses the support shaft 1 and the first bevel gear 2, and a rack housing H <b> 2 that houses the rack shaft 3 and the rotating body 5. The rack housing H2 is divided into a first housing H2a that supports the right end in the view of the rotating body 5 and a second housing H2b that supports the left end in the view of the rotating body 5. The first housing H2a is integrally formed with the support shaft housing H1. The first housing H2a and the second housing H2b are connected to each other by a screw 10.
[0013]
The electric motor M is fixed to the holding member 8 in a state in which the outer periphery M1 of the front portion of the casing is fitted to the opening edge 8a of the upper end portion of the holding member 8. The axis of the output shaft m of the electric motor M forms an acute angle with respect to the axis of the rack shaft 3. The support shaft 1 has a base end 1a attached to the output shaft m of the electric motor M so as to be integrally rotatable. The axis of the support shaft 1 is disposed on an extension of the axis of the output shaft m of the electric motor M. The intermediate portion of the support shaft 1 is rotatably held by the holding member 8 via a pair of rolling bearings 12. Therefore, the support shaft 1 is provided concentrically with the inner periphery of the holding member 8.
[0014]
The outer periphery of the lower end side of the holding member 8 is rotatably fitted in a fitting hole H1a formed in the spindle housing H1. The outer peripheral axis X of the holding member 8 is eccentric with respect to the inner peripheral axis Y. Therefore, by rotating the holding member 8, the first bevel gear 2 can be moved in the radial direction together with the electric motor M and the support shaft 1. Further, the holding member 8 is assembled to the support shaft housing H1 so that it can be biased further in the direction of the second bevel gear 4 from the state of FIG. 1 in which the first bevel gear 2 is engaged with the second bevel gear 4. It has been.
A hook-shaped first spring receiving portion 8b protrudes from an intermediate portion of the holding member 8 in the axial direction, and an enlarged diameter portion 8c for attaching the electric motor M is provided at the upper end portion. . The enlarged diameter portion 8c is integrated with the main body by screws or the like.
[0015]
Between the first spring receiving portion 8b and the enlarged diameter portion 8c, a second spring receiving portion 21, a friction member 22 and a rotation prevention ring 23 are arranged. The second spring receiving portion 21 is ring-shaped, and is rotatably fitted to the spindle housing H1 with one side faced to the first spring receiving portion 8b with a gap. ing. The friction member 22 has a flat ring shape and is sandwiched between the second spring receiving portion 21 and the rotation prevention ring 23. The friction member 22 is made of metal, resin, ceramics, or a composite material having a large friction coefficient so as to restrict relative rotation between the second spring receiving portion 21 and the rotation prevention ring 23.
[0016]
The anti-rotation ring 23 is attached to the spindle housing H1 by screwing a male screw on the outer periphery thereof into a female screw of the spindle housing H1. Further, the detent ring 23, the lock nut 25 screwed onto the male threaded in its outer periphery, the rotation is Ri Contact is restricted, thereby, the second spring seat 21 is rotated via the friction member 22 Is regulated. Furthermore, a plurality of engagement holes 23a for engaging a tool such as a ring turning are formed on the back surface of the rotation stop ring 23. Further, a gap for inserting the tool is provided between the back surface of the rotation prevention ring 23 and the enlarged diameter portion 8 c of the holding member 8. Therefore, in a state where the lock nut 25 is loosened, the first spring receiving portion 8b is rotated via the friction member 22 by engaging a tool with the engagement hole 23a through the gap and rotating the rotation prevention ring 23. Can be made.
[0017]
A spring 24 for rotating and biasing the holding member 8 is interposed between the first spring receiving portion 8 b and the second spring receiving portion 21. As shown in FIG. 3, the spring 24 is C-shaped, and one end 24b of the spring 24 is locked to a locking pin 8d protruding from the first spring receiving portion 8b, and the other end 24a is second. In this state, the holding member 8 is urged to rotate and the first bevel gear 2 is moved toward the second bevel gear 4 in the direction of the second bevel gear 4. Preload is applied. Thus, since the spring 24 is C-shaped and interposed between the spring receiving portions 8b and 21, the spring 24 can be easily arranged in a small space, and the holding member 8 can be easily arranged. The configuration can be rotationally biased. Further, since the second spring receiving portion 21 can be rotated with respect to the non-rotating ring 23 in a state where the lock nut 25 is loosened, the urging force of the spring 24 can be easily set to an appropriate value. .
In addition, between the front-end | tip of the latching pin 8d of the said spring receiving part 8b and the 2nd spring receiving part 21, and between the front-end | tip of the pin 21a of the 2nd spring receiving part 21 and the 1st spring receiving part 8b. In this case, when the non-rotating ring 23 is further screwed to rotate the second spring receiving portion 21, a clearance for allowing the second spring receiving portion 21 to approach the first spring receiving portion 8b. Is provided.
[0018]
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 a steered wheel (not shown) via a ball joint 16, and the steered wheel can be steered by a linear movement thereof. A rack gear constituting a part of the rack and pinion mechanism 9 is formed on the right end side of the rack shaft 3 in the drawing.
[0019]
The second bevel gear 4 is fitted and attached to the outer periphery of the rotating body 5, and in this state, the rotation with respect to the rotating body 5 and the movement in the axial direction are restricted. The axis of the second bevel gear 4 is made to coincide with the axis of the rack shaft 3, and the teeth of the first bevel gear 2 are meshed with the teeth of the outer periphery of the second bevel gear 4. is there. The first bevel gear 2 is integrally formed at the tip of the support shaft 1.
[0020]
The rotating body 5 is fitted to the outer periphery of the rack shaft 3 with a gap, and the right end portion thereof is rotatably supported by the first housing H2a via the first rolling bearing 13, and the left end portion is the first end portion. The second housing H2b is rotatably supported by two rolling bearings 14.
The ball screw 6 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.
[0021]
The rack and pinion mechanism 9 includes a steering shaft 9a that is rotationally driven by a steering wheel (not shown), a pinion gear that is coupled to the steering shaft 9a, and a rack gear that is meshed with the pinion gear and formed on the rack shaft 3. Thus, the rack shaft 3 can be linearly moved in accordance with the rotation operation of the steering wheel. The rotational torque of the steering shaft 9a is detected by a torque sensor, and the electric motor M is driven by the power corresponding to the detected rotational torque, and a steering assist force is applied to the rack shaft 3.
[0022]
When the electric power steering apparatus having the above configuration is assembled, the holding member 8 is eccentrically rotated in a predetermined direction to move the first bevel gear 2 together with the support shaft 1 in the direction of the second bevel gear 4. The backlash of the meshing portions of the two bevel gears 2 and 4 can be adjusted. Therefore, coupled with the point that the electric motor M does not need to be attached to and detached from the spindle housing H1 many times, the backlash can be adjusted easily and quickly.
[0023]
In addition, by rotating the detent ring 23 in a predetermined direction with the backlash adjusted, it is possible to generate a biasing force on the spring 24 and to rotate and bias the holding member 8. One bevel gear 2 can always be pressed in the direction of the second bevel gear 4. For this reason, even if the bevel gears 2 and 4 are worn due to long-term use, the first bevel gear 2 can be moved to the second bevel gear 4 side by following the wear. As a result, it is possible to prevent backlash from occurring at the meshing portions of the two bevel gears 2 and 4 over a long period of time. Moreover, since the urging force of the spring 24 can be adjusted simply by rotating the detent ring 23, the adjustment is easy and the first bevel gear 2 is moved in the radial direction. Therefore, it is possible to prevent the power transmission efficiency from being lowered due to the fact that the meshing point between the first bevel gear 2 and the second bevel gear 4 is largely shifted in the axial direction from the preset meshing point. Can do.
[0024]
Further, when the bevel gears 2 and 4 are worn to some extent and the urging force of the spring 24 is reduced, the lock nut 25 is loosened and the detent ring 23 is tightened to tighten the second spring receiving portion. 21 can be rotated to adjust the urging force of the spring 24 to an appropriate value. For this reason, it is possible to prevent backlash from occurring for a longer period of time.
[0025]
The electric power steering apparatus according to the present invention is not limited to the above-described embodiment. For example, the spring 24 is formed of a torsion coil spring, and the rotational motion of the rotating body 5 is converted into the linear motion of the rack shaft 3. Various design changes such as using a bearing screw instead of the ball screw 6 as the motion conversion mechanism can be made.
The electric power steering device of the present invention is also applied to an electric power steering device of a type in which the axes of the first bevel gear 2 and the second bevel gear 4 intersect each other at right angles instead of acute angles. be able to.
[0026]
【The invention's effect】
As described above, according to the electric power steering device of the first aspect, the backlash of the meshing portion of the both bevel gears can be adjusted only by adjusting the position of the holding member in the rotational direction. Shim adjustment is unnecessary, and the backlash can be adjusted easily and quickly.
Further, since the first bevel gear can be moved to the second bevel gear side following the wear of each bevel gear, backlash occurs at the meshing portion of both bevel gears due to the wear. Can be prevented. For this reason, generation | occurrence | production of a rattling sound can be prevented, without requiring maintenance over a long period of time. In addition, since the backlash is adjusted by moving the first bevel gear in the radial direction, there is no possibility that a preset meshing point is shifted. For this reason, it can prevent that the power transmission efficiency of both bevel gears falls.
[0027]
In addition , the spring can be easily arranged in a small space, and the holding member can be urged to rotate with a simple configuration. In addition, when the wear force of each bevel gear progresses to some extent and the biasing force of the spring decreases, the biasing force of the spring can be adjusted to an appropriate value by rotating the second spring receiving portion. Rushing can be prevented for a longer period.
[0028]
Furthermore , since the second spring receiving portion can be rotationally adjusted via the friction member by rotating the non-rotating ring, the adjustment is easy. Moreover, since the relative rotation of the second spring receiving portion and the rotation prevention ring can be allowed, the rotational direction position of the second spring receiving portion with respect to the holding member can be set easily and appropriately.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an electric power steering apparatus according to the present invention.
FIG. 2 is an enlarged cross-sectional view of the main part of the previous figure.
FIG. 3 is an exploded perspective view of a spring portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Support shaft 2 1st bevel gear 3 Rack shaft 4 2nd bevel gear 5 Rotating body 6 Ball screw (rotational motion conversion mechanism)
8 Holding member 8b First spring receiving portion 9 Rack and pinion mechanism 21 Second spring receiving portion 22 Friction member 23 Non-rotating ring 24 Spring M Electric motor m Output shaft H1 Support shaft housing H2 Rack housing

Claims (1)

A support shaft connected to the output shaft of the electric motor so as to be integrally rotatable, a first bevel gear provided at the tip of the support shaft, a support shaft housing for accommodating the support shaft, and a steered wheel by linear movement. A rack shaft to be steered, a rack housing that supports the rack shaft so as to be linearly movable, a second bevel gear meshed with the first bevel gear in a state of crossing each other's axes, and A rotating body rotatably supported by the rack housing in a state of surrounding the rack shaft and having the second bevel gear attached thereto; and a rotary motion converting mechanism for converting the rotational motion of the rotating body into linear motion of the rack shaft For rotating the rack by linearly transmitting the rotation of the electric motor to the rotating body via the support shaft, the first bevel gear and the second bevel gear, and for turning the steered wheels. Electric power to assist manual steering force In the steering apparatus,
A cylindrical holding member provided inside the support shaft housing so as to be eccentrically rotatable, attaching the electric motor to one end, and holding the support shaft concentrically with an inner peripheral surface;
A spring that biases the holding member in a predetermined rotational direction and elastically presses the first bevel gear against the second bevel gear ;
The outer periphery of the lower end side of the holding member is rotatably fitted in a fitting hole formed in the spindle housing,
A flange-shaped first spring receiving portion protrudes from the axially intermediate portion of the holding member, and a diameter-expanding portion for attaching the electric motor is provided at one end, and faces the first spring receiving portion. The ring-shaped second spring receiving portion is rotatably arranged, and the spring is formed in a C shape and interposed between the first spring receiving portion and the second spring receiving portion, The second spring receiving portion is attached by a detent ring attached to the spindle housing in a state where one end of the spring is locked to the first spring receiving portion and the other end is locked to the second spring receiving portion. The rotation of the
The detent ring is screwed into the spindle housing, and its rotation is restricted by a lock nut, and the detent ring is fitted to the back surface of the second spring receiving portion via a friction member so as to be integrally rotatable. And
A base end portion of the support shaft, an electric power steering apparatus characterized that you have mounted for integral rotation to the output shaft of the electric motor.

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