JP2957394B2 - Steering gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a steering rudder system.

[0002]

2. Description of the Related Art As a rear wheel steering apparatus, there has been provided a rear wheel steering apparatus in which a rear wheel steering shaft is moved in an axial direction by a rotational force of a motor to steer a rear wheel. If a failure occurs in the electric system including the motor and the sensors, the centering spring conventionally operates the rear-wheel steering shaft in the same phase (the rear-wheel steering direction is the same as the front-wheel steering direction). The vehicle is returned to a neutral position that is not in the opposite phase (the steering direction of the rear wheels is opposite to the steering direction of the front wheels). That is, this is a fail-safe concept of returning the rear wheel to the neutral position in an emergency.

[0003]

However, i) In order to obtain a sufficient return force to the neutral position, it is necessary to increase the load of the centering spring. For this reason, the output of the motor has to be increased, which is wasteful. ii) In the conventional fail-safe method, since the operation of returning the rear wheel to the neutral position is performed suddenly in an emergency, the returning operation may adversely affect the running performance of the vehicle. It was not always desirable.

In order to solve the above problems i) and ii), a trapezoidal screw mechanism is used as a non-reversible transmission mechanism in the drive transmission path from the motor to the rear wheel steering shaft, and the motor is driven by the rear wheel drive shaft. Can be driven, but the rear wheel drive shaft cannot drive the motor. However,
The trapezoidal screw mechanism has a large backlash in the axial direction, which may cause new problems such as poor steering stability and noise due to the backlash.

Conventionally, as a mechanism for adjusting the backlash of a general trapezoidal screw mechanism, two pairs of female screw members opposed to each other are arranged around a male screw member.
In some cases, the female screw members of each group are bolted together to adjust the backlash between the groups. However, since this adjusting mechanism becomes large, when this adjusting mechanism is employed in the rear wheel steering device, there is a problem that the rear wheel steering device becomes large. Further, when adopted in a rear wheel steering device, the adjustment mechanism is disposed in the gearbox. However, there is a problem that the adjustment mechanism cannot perform adjustment from outside the gearbox.

An object of the present invention is to provide a steering rudder device that Ru can adjust the Kune Flip backlash such that increasing the size.

[0007]

To achieve the above object, according to an aspect of, engagement Ru steering rudder device in claim 1, while being rotatably supported by the housing, and a female screw member that is rotated by the motor, the female screw member A male screw to be screwed into is formed,
Steering wheels via steering axis by moving in axial direction
That a steering rudder device that having a male threaded member, includes a resilient biasing member for biasing in a direction orthogonal on Kieu threaded member with the axis, adjusts the backlash engagement portion of the each other the screw member comprising a backlash adjustment mechanism, the backlash
The adjusting mechanism has a flat surface provided on the steering shaft and an opposing surface.
Male screw part by being inserted between the inner surface of the housing
A member for restricting relative rotation of the material with respect to the housing is included.

[0008] Procedure steering device Ru engaging in claim 2, in have your <br/> to claim 1, said backlash adjustment mechanism, the preload of the upper Symbol be operable from outside the housing the resilient biasing member It is characterized by further including a member for adjusting.

[0009]

SUMMARY OF] According to the invention according to claim 1, by energizing in a direction perpendicular to the male screw member and the axis by an elastic biasing member, backlash Flip sleep with a simple structure is automatically adjusted . Further, linen Ji engagement portion by the change over time even when worn, and following this, backlash is adjusted automatically.

Further, bus Kkurasshi adjustment mechanism, by including a member for restricting the relative rotation with respect to the housing of the male screw member, it is not necessary to provide a member for restricting the relative rotation separately, the structure is simplified. According to the second aspect of the invention, the operability of the backlash adjustment is improved by adjusting the preload of the elastic urging member from outside the housing.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a partial cross-sectional side view of a main part of a rear wheel steering device as one embodiment of the present invention, FIG. 2 is a plan view of the main part, and FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1, and FIG. 5 is a cross-sectional view taken along the line VV of FIG.

The rear wheel steering system P includes: 1) a housing H fixed to a vehicle, 2) a rotary motor M, 3) a worm 2
And a worm wheel 3 and a reduction mechanism R driven by the motor M. 4) A trapezoidal screw mechanism D including a trapezoidal male screw member 200 and a trapezoidal female screw member 300 and driven by the reduction mechanism R. Driven by mechanism D, axial direction (left-right direction in FIG. 1)
, And a rear wheel steering shaft 5 for steering a rear wheel (not shown) via a tie rod T; and 6) a backlash adjusting mechanism E for removing the backlash of the trapezoidal screw mechanism D. The speed reduction mechanism R and the trapezoidal screw mechanism D
The drive transmission mechanism Q is constituted by the above. The reverse transmission efficiency of the drive transmission mechanism Q (transmission efficiency when transmitting an input from the rear wheel steering shaft 5 to the motor M) is set to be zero.

The rear wheel steering shaft 5 and the tie rod T are connected by a universal joint (not shown) having a joint center T1. In the rear wheel steering device P, the rotational motion of the motor M is given to the trapezoidal screw mechanism D via the speed reduction mechanism R, and is converted into linear motion along the rear wheel steering shaft 5 by the trapezoidal screw mechanism D. , The rear wheels are steered.

Referring to FIG. 1, a housing H has a cylindrical shape through which a rear wheel steering shaft 5 is inserted. The mechanism R and the worm wheel 3 are arranged. The housing H includes a pair of angular ball bearings 21.
, The trapezoidal female screw member 300 is rotatably supported. Each of the angular ball bearings 21 includes an annular outer ring 21 a fixed to an inner surface of the housing H, and a trapezoidal female screw member 3.
An annular inner race 21b fixed to the outer peripheral surface of the outer race 00 and a plurality of balls 21c interposed between the two races 21a, 21b.

Each inner ring 21b is axially positioned with respect to the trapezoidal female screw member 300 such that the interval between the inner rings 21b is predetermined. One outer ring 21a
Are positioned in the axial direction with respect to the housing H, and the other outer ring 21a is pressed by a cap HC described later in a direction approaching the one outer ring 21a. In this state, a required preload is applied to the angular ball bearing 21.

An opening is provided on the right end surface of the housing H, and a female screw He is formed on the inner peripheral surface of the opening. The opening of the housing H is substantially closed by the annular cap HC in which the rear wheel steering shaft 5 is inserted. On the outer peripheral surface of the cap HC, a male screw HC1 that meshes with the female screw He of the housing H is formed. The cap HC has an insertion hole HC2 through which the rear wheel steering shaft 5 is inserted. A slight gap is provided between the inner peripheral surface of the insertion hole HC2 and the outer peripheral surface of the rear wheel steering device 5. At an end of the cap HC, a boot holding portion HC3 is formed, which is covered with and holds an end of a bellows-like rubber boot member BT that covers the periphery of a connection portion between the rear wheel steering shaft 5 and the tie rod T. I have.

The cap HC is fixed to the housing H by a lock nut HR while being screwed into the female screw He at the opening. A plurality of radial projections HR1 are formed on the outer periphery of the lock nut HR. The lock nut HR is rotated by engaging a predetermined claw tool (not shown) with the projection HR1. As described above, the cap HC is connected to one of the angular ball bearings 21.
A predetermined preload is applied to the angular ball bearing 21 in this state. This preload can be easily adjusted by setting the screwing amount of the cap HC.

Referring to FIG. 1 and FIG. 3, the trapezoidal female screw member 300 is a cylindrical member arranged concentrically around the rear wheel steering shaft 5. On the outer peripheral portion of the trapezoidal female screw member 300, a worm wheel 3
Are connected so as to be integrally rotatable. Trapezoid female screw member 30
At the central portion in the axial direction of 0, a female screw portion 300a of a trapezoidal screw is formed on the entire circumference of the inner peripheral surface. The worm wheel 3 has an annular shape. Referring to FIG. 4, worm 2 meshed with worm wheel 3 is connected to output shaft 1 of motor M, and rotates integrally with output shaft 1.

Referring to FIGS. 1 and 3, the trapezoidal male screw member 200 is a cylindrical member interposed between the inner peripheral portion of the trapezoidal female screw member 300 and the outer peripheral portion of the rear wheel steering shaft 5. The trapezoidal male screw member 200 is arranged concentrically with the rear wheel steering shaft 5. On the outer periphery of the trapezoidal male screw member 200, the trapezoidal male screw portion 20 meshing with the female screw portion 300 a is formed all around.
0a is formed. The trapezoidal male screw member 200 is keyed to the rear wheel steering shaft 5 by the half moon key 9, and the relative rotation between the trapezoidal male screw member 200 and the rear wheel steering shaft 5 is regulated. Also, the snap ring 10A and the caulking member 1
0B restricts axial movement of the trapezoidal male screw member 200 with respect to the rear wheel steering shaft 5. The snap ring 10A and the caulking member 10B are respectively fixed to a pair of outer peripheral grooves of the rear wheel steering shaft 5 and have a trapezoidal male screw member 20.
0 are in contact with both ends.

The male screw portion 200a and the female screw portion 30
The trapezoidal screw constituting Oa is preferably a multi-start thread. This is for the following reason. That is, for example, in order to improve the efficiency with JIS-TR36, PCD33, lead 6, and a single-thread screw having a total tooth height of 3 mm,
When the lead is made larger, the overall size becomes larger (the efficiency of the trapezoidal screw is proportional to the lead), which is against the demand for downsizing the rear wheel steering device. On the other hand, for example, in the case of a two-thread trapezoidal screw with a lead of 10 mm (pitch: 5), a large lead can be secured while keeping the total tooth length at 3 mm (in this case, the above-mentioned single-thread screw and In comparison, the efficiency can be improved by about 15%).

Referring to FIGS. 1 and 5, the backlash adjusting mechanism E will be described. The backlash adjusting mechanism E radially presses the trapezoidal male screw member 200 against the trapezoidal female screw member 300 via the rear wheel steering shaft 5,
The play of the screw fitting portion is reduced to zero. The backlash adjusting mechanism E includes: 1) a resin slide member E1 that abuts on the rear wheel steering shaft 5 as a member that restricts relative rotation of the trapezoidal male screw member 200 with respect to the housing H;
2) fixed in a screw hole Hh formed in the housing H,
A screw member E2 serving as a member for adjusting the preload of a compression coil spring E3, which will be described later; and 3) a slide member E interposed between the screw member E2 and the slide member E1.
1) a compression coil spring E3 as an elastic urging member for pressing the first member 1 against the rear wheel steering shaft 5; and 4) a lock nut E4 for fixing the screw member E2 to the housing H.

The slide member E1 has a coil spring receiving recess E11 opened at one end. At the other end of the slide member E1, a pair of flat surfaces 5a of the rear wheel steering shaft 5,
There is provided a pair of U-shaped holding portions E14 for holding 5b. The pair of flat surfaces 5a and 5b are formed with a predetermined width in the axial direction of the rear wheel steering shaft 5, and are parallel to each other. Each of the holding portions E14 has a flat surface 5a, 5b.
And a slight interference is provided between them, and the inner surfaces Hb, Hb of the housing H opposed thereto are fitted with a small gap therebetween to hold the flat surfaces 5a, 5b. Thereby, the relative rotation of the rear wheel steering shaft 5 with respect to the housing H is restricted. The slide member E1 is made of a self-lubricating resin such as an oil-impregnated plastic. Therefore, even if the slide member E1 is fitted to the flat surfaces 5a and 5b of the rear wheel steering shaft 5 to restrict the rotation of the rear wheel steering shaft 5 as described above, Allows smooth movement in the axial direction.

Further, the slide member E1 is provided with the holding portion E
14, there is a concave pressing portion E <b> 12 which comes into contact with and presses the peripheral surface of the rear wheel steering shaft 5. The screw member E2 has a screw portion E21 on the outer periphery, and has a wrench hole E22 on its end face for introducing and fitting a hexagon wrench for turning the screw member. The screwing position of the screw member E2 is determined by the end surface E23 of the screw member E2 and the end surface E13 of the slide member E1.
And a predetermined gap (not shown, for example, 0.0
(About 6 to 0.09 mm).

The compression coil spring E3 is housed in the coil spring housing recess E11 of the slide member E1.
End surface E23 of screw member E2 and coil spring receiving recess E11
Interposed between the bottom surface. The compression coil spring E3 is
The trapezoidal male screw member 200 is elastically pressed against the trapezoidal female screw member 300 via the slide member E1 and the rear wheel steering shaft 5. Thereby, the female screw part 300a and the male screw part 20
0a is pressed so that there is no play in the axial direction between the two trapezoidal screw members 200 and 300. In particular, even when the trapezoidal male screw member 200 or the trapezoidal female screw member 300 is eccentrically rotated, the resiliently biased trapezoidal male screw member 200 can follow the male screw portion 200a while pressing the male screw portion 200a against the female screw portion 300a. .

According to this embodiment, the motor M
The trapezoidal female screw member 300 is rotationally driven via the speed reduction mechanism R, and the trapezoidal male screw member 200 meshing with the trapezoidal female screw member 300 is axially moved integrally with the rear wheel steering shaft 5 to steer the rear wheel. . Further, since the rear wheel steering angle is small (generally about several degrees), the force for returning the rear wheel to the neutral position is small, and the reverse transmission efficiency of the drive transmission mechanism Q is zero. Therefore, in an emergency where the electric system has failed, the rear wheels are maintained at the steering angle at that time. As a result, unnecessary sudden operation is not performed during traveling, which is more preferable in terms of fail-safe.

The input from the rear wheel steering shaft 5 tends to be transmitted to the motor M via the trapezoidal screw mechanism D and the worm gear mechanism. On the other hand, since the trapezoidal screw mechanism is combined with the worm gear mechanism, the following advantages can be obtained. That is, even when the reverse transmission efficiency of the trapezoidal screw mechanism D cannot be reduced so much, the reverse transmission efficiency of the entire drive transmission mechanism Q can be reduced to zero by adjusting the reduction ratio of the worm gear mechanism. Therefore, the degree of freedom in design is high. Further, by using the worm gear mechanism, a higher reduction ratio can be achieved with a smaller size as compared with the case where another reduction gear mechanism is used.

In addition, since the conventional centering spring can be omitted, the structure can be further simplified. Conventionally, against the centering spring,
Although it was necessary to increase the output of the motor, in the present embodiment, it is not necessary to unnecessarily increase the output of the motor M, and the size and weight can be reduced. Further, by the backlash adjusting mechanism E including the compression coil spring E3, the male screw portion 200a of the trapezoidal male screw member 200 is changed to the female screw portion 300a.
Elastically biased. Therefore, without being affected by the eccentric rotation or the like of the trapezoidal male screw member 200,
0a and the pressing state of the male screw part 200a can be ensured. As a result, the relative axial play between the trapezoidal male screw member 200 and the trapezoidal female screw member 300 can be eliminated. Therefore, the rotational motion of the motor M can be converted into the linear motion of the rear wheel steering shaft 5 without delay. For this reason, steering stability can be improved, and generation of noise due to backlash can be prevented.

In addition, the housing H of the rear wheel steering shaft 5 is moved by the slide member E1 of the backlash adjusting mechanism E.
The relative rotation with respect to was regulated. Therefore, there is no need to separately provide a member for regulating the relative rotation of the rear wheel steering shaft 5, and the structure of the rear wheel steering device P can be simplified. Moreover, the backlash adjusting mechanism E can adjust the backlash from outside the housing H, so that the operability is very good.

The present invention is not limited to the above-described embodiment, and various design changes can be made without changing the gist of the present invention.

[0030]

Effects of the Invention According to the first aspect of the invention, since the biases in the direction perpendicular to the male screw member and the axis by an elastic biasing member, without increasing the size of the steering rudder device with a simple structure, Ji roots Can automatically adjust the backlash. Further, even when the linen Ji engagement portion by the aging is worn, it is possible to automatically adjust the backlash by following this.

Further, it urges via a member which is elastic biasing member for restricting the relative rotation with respect to the housing of the male screw member,
Since the mechanism for adjusting the backlash is also used as the mechanism for regulating the relative rotation, there is no need to provide a separate mechanism for regulating the relative rotation. Therefore, the structure can be simplified and the steering device can be downsized.

According to the second aspect of the present invention, since the preload of the elastic biasing member can be adjusted from outside the housing, the operability of the backlash adjustment is very good.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view of a main part of a rear wheel steering device according to an embodiment of the present invention.

FIG. 2 is a plan view of a main part of the rear wheel steering device.

FIG. 1 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view taken along the line VV of FIG. 1;

[Description of Signs] H Housing M Motor 200 Trapezoidal Male Thread Member 300 Trapezoidal Female Thread Member E Backlash Adjusting Mechanism E1 Slide Member (Member for Restricting Relative Rotation of Trapezoidal Male Thread Member) E2 Screw Member (Member for Preload Adjustment) E3 Compression Coil Spring (Elastic biasing member)

Claims (2)

(57) [Claims] While being axially supported by 1. A housing, and a female screw member that is rotated by a motor, and female threaded member screwed to the male screw is formed, through a steering shaft by moving in the axial direction a steering rudder device you Yes <br/> a male threaded member you steering wheel includes a resilient biasing member for biasing in a direction orthogonal on Kieu threaded member with the axis, the screw member to each other A backlash adjusting mechanism for adjusting the backlash of the threaded portion of the steering shaft.
Between the surface and the inner surface of the housing facing it.
The relative rotation of the male screw member with respect to the housing.
Misao rudder device you comprising a member win. 2. The steering system according to claim 1, wherein the backlash adjusting mechanism is operated from outside the housing.
Possible to adjust the preload of the elastic biasing member
Misao rudder device further comprising a member.