JPH0692245A - Steering gear - Google Patents

Abstract

PURPOSE:To smooth operation and improve durability while improving a steering feeling in a steering gear to reduce the steering gear ratio along with the increase of the rotational angle of the steering wheel. CONSTITUTION:An intermediate rotary member 38 is eccentrically provided between an input shaft 11 and output shaft 13 connected to a steering wheel, and the rotation of the input shaft is moderated by a reduction gear 40 consisting of an input pinion 41 and internal gear 42 to be transmitted to the intermediate rotary member 38. The rotation of the intermediate rotary member is transmitted to the output shaft 13 through a steering property giving mechanism 45 engaging a projection 48 eccentrically provided on the output shaft 13 with a cam groove 47 formed diametrally in the end face. An extended shaft part 12 formed to extend rearward from the rear end of the input shaft 11 provided with the input pinion 41 is supported with a housing 10. Also, a controller 20 provided on the input shaft 11 increases an assist force given to an output operating member 14 by a force increasing device 30 along with the increase of torque applied to the input shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device for steering wheels of an automobile, and more particularly, to a power system in which a steering gear ratio (steering wheel rotation angle / tire cutting angle) is decreased in accordance with an increase in steering wheel rotation angle. Type steering device.

[0002]

2. Description of the Related Art There are various types of front wheel steering devices such as a rack and pinion type, a ball screw type, and a worm pin type. However, since a normal front wheel steering device has a substantially constant steering gear ratio, a steering wheel near a neutral position is used. Otherwise, the feeling of turning when the steering wheel is turned is insufficient, and the maximum steering wheel rotation angle required to obtain the desired maximum front wheel steering angle is large (for example, 540 degrees). If the steering gear ratio is reduced in order to solve this problem, there is a feeling of excessive cutting near the neutral position of the steering wheel.

In order to solve such a problem, the applicants have previously proposed a steering device according to Japanese Patent Application No. 3-240398. As shown in the main part of FIG. 5, an intermediate rotating member 2 and an output shaft 3 connected to an input shaft 1 are provided eccentrically with respect to each other by a predetermined amount, and a diametrical cam groove is provided between the two members 2 and 3. 4a and a protrusion 4b engaging with the steering characteristic imparting mechanism 4 are provided. With this, the steering gear ratio is increased in accordance with an increase in the rotation angle of the input shaft 1 connected to the steering wheel from the steering neutral position. The above problem is solved by gradually reducing the number. Further, in this technique, the rotation angle of the intermediate rotation member 2 is limited to within 180 degrees, but since it is desired that the rotation angle of the steering wheel is 180 degrees or more (for example, 240 degrees), the rotation angle between the input shaft 1 and the intermediate axis is intermediate. Rotating member 2
A speed reduction mechanism 5 including an input pinion 5a and an internal gear 5b is provided between them. Further, this is a hydraulic front wheel power steering apparatus that operates a power cylinder by a servo valve that operates according to the torque applied to the input shaft 1 to apply an assist force to an output operation member (rack bar).

[0004]

However, since the input pinion 5a of the reduction gear mechanism 5 is a cantilever support that largely projects from the bearing 6 that supports the input shaft 1, the transmission mechanism of this reduction gear mechanism 5 is transmitted. When the torque increases, the load applied to the meshing portion causes the input pinion 5a to bend and the load on the bearing 6 to increase, which reduces the rigidity of steering, adversely affects the meshing of the speed reduction mechanism 5, and smooths the steering device. However, there is a problem in that it impairs proper operation and reduces durability. It is an object of the present invention to solve such a problem and to obtain a steering device that can obtain a good steering feeling and a smooth operation and is excellent in durability.

[0005]

To this end, the steering apparatus according to the present invention, as shown in FIGS. 1 to 4, has an input shaft 11 connected to a steering handle and rotating together, an output shaft 13, and an interlocking mechanism. An output actuating member 14 that is connected to the input shaft 11 via 15 and steers the wheels via a steering link; and a booster 30 that applies an assisting force to the output actuating member.
The control device 20 is provided on the input shaft 11 and operates according to the torque applied to the input shaft 11 to change the assist force applied to the output operating member 14 by the booster device 30, and a housing 10 that supports these members. In the steering device, the intermediate rotation member 38 eccentrically supported by the housing 10 between the input shaft 11 and the output shaft 13 arranged coaxially with each other, and the intermediate member between the input shaft 11 and the intermediate rotation member 38. An input pinion 41 integrally provided at an end of the rotary member 38 and an internal gear 42 integrally provided at the intermediate rotary member 38 and meshing with the input pinion 41 are provided to rotate the input shaft 11. A deceleration mechanism 40 for decelerating and transmitting to the intermediate rotating member 38, and a diametrical direction formed on one of the end faces of the intermediate rotating member 38 and the output shaft 13 which face each other. The cam groove 47, the projection 4 engaging the mutually other facing end surfaces of the eccentric from the rotation center and provided to protrude in the axial direction in the cam groove 47
8, a steering characteristic imparting mechanism 45 that transmits the rotation of the intermediate rotating member 38 to the output shaft 13 while gradually reducing the reduction ratio according to the increase in the rotation angle of the input shaft 11 from the steering neutral position. The output shaft 13 of the input shaft 11
An extension shaft portion 12 is integrally and coaxially formed at a side end portion, extends through the intermediate rotation member 38, extends toward the output shaft 13, and is rotatably supported by the housing 10. To do.

In the present invention, the extension shaft portion 12 may be supported by the housing 10 via the output shaft 13.

Alternatively, the extension shaft portion 12 may be directly supported by the housing 10.

[0008]

The rotation of the input shaft 11 rotating with the steering wheel is reduced by the reduction mechanism 40 and transmitted to the intermediate rotating member 38, and transmitted to the output shaft 13 through the steering characteristic imparting mechanism 45 including the cam groove 47 and the protrusion 48. The interlocking mechanism 15
And steering the wheels via the output actuating member 14. At this time, the load applied to the meshing portion increases as the transmission torque of the reduction gear mechanism 40 increases, but the input pinion 41 of the reduction gear mechanism 40 is supported by the housing 10 on both the input shaft 11 side and the output shaft 13 side. Therefore, the support rigidity increases, the bending of the input pinion 41 due to the load applied to the meshing portion decreases, and the load applied to some bearings does not increase.

[0009]

As described above, according to the present invention, the deflection of the input pinion due to the load applied to the meshing portion of the reduction mechanism is reduced, and the load on the bearing is not increased. It is possible to obtain a steering device having a good steering feel and a smooth operation and excellent durability.

[0010]

EXAMPLE A first example shown in FIGS. 1 to 3 will be described below. As shown in FIG. 1, a housing 10 of a steering apparatus according to this embodiment includes a valve housing 1 that is screwed and fixed to each other.
0a and the gear housing 10b.
Input shaft 11 and its second half 1 arranged coaxially with each other
1a is a valve housing 10 via bearings 17a and 17b.
It is supported in a and is elastically connected by a torsion bar 16 so as to be relatively rotatable.

On the rear side of the input shaft 11, an intermediate rotating member 38 is supported in the gear housing 10b via two bearings 19 so as to be eccentric in parallel therewith. The amount of eccentricity between these is e. Input shaft 11
11b which is fixed to the rear part of the rear half 11a of the vehicle through a key 11c and a nut 50 and is supported by a bearing 17c.
An input pinion 41 is formed on the input pinion 4
1 and an internal gear 42 coaxially formed in the front half of the intermediate rotation member 38 mesh with each other to form a reduction mechanism 40 that reduces the rotation of the input shaft 11 and transmits the rotation to the intermediate rotation member 38. There is.

The output shaft 13 of which the output flange 39 of the steering characteristic imparting mechanism 45, which will be described later, is coaxially fixed to the front end via the key 39a, has the input shaft 1 via the bearings 18a and 18b.
It is supported by the gear housing 10b located one rearward. A rack bar (output actuating member) 14 is supported on the gear housing 10b so as to move in a three-dimensional manner with the output shaft 13 so as to be axially movable.
The both 13, 14 are interlocked by an interlocking mechanism 15. In this embodiment, the interlocking mechanism 15 includes the output shaft 13
And a rack 15b formed in a part of the rack bar 14 and meshing with the pinion 15a. Both ends of the rack bar 14 are respectively connected to the left and right front wheels via steering links (both not shown). Are linked to.

The extension shaft portion 12, which is coaxially protruded rearward from the rear end of the rear half 11a of the input shaft 11, passes through a hole 38a formed at the center of the intermediate rotary member 38 and extends rearward. There is. The input shaft 11 and the output shaft 13 are arranged coaxially, and the tip of the extension shaft portion 12 has a needle bearing 12a.
It is supported by the output shaft 13 via.

Next, referring to FIGS. 1 and 2, a steering characteristic imparting mechanism 45 for transmitting the rotation of the intermediate rotating member 38 to the output shaft 13 while gradually reducing the reduction ratio in accordance with the increase of the rotation angle from the steering neutral position. Explain. A diametrically extending cam groove 47 is formed on the rear end surface of the intermediate rotation member 38, and a projection 48 is offset from the rotation axis O3 of the output shaft 13 by a distance R on the front end surface of the output flange 39 opposed to the cam groove 47. It is provided so as to project in the axial direction. This distance R is larger than the amount of eccentricity e between the rotation axes O2 and O3 of both members 38 and 13. The protrusion 48 is composed of a pin 48a fixed to the output flange 39 in parallel with the rotation axis O3, and a roller 48b rotatably provided on the pin 48a via a needle roller 48c. The cam groove 47 is rotatably engaged in the cam groove 47 with substantially no clearance. In this embodiment, the cam groove 47 of the steering characteristic imparting mechanism 45 is on the side of the intermediate rotating member 38, and the projection 48 is on the output shaft 13.
Although it is provided on the side of the intermediate rotation member 38,
On the side, the cam groove 47 may be provided on the output shaft 13 side.

As shown in FIG. 1, the front wheel steering system of this embodiment is provided with a power steering system including a servo valve (control system) 20 and a power cylinder (power booster) 30. The rotor valve member 21 of the servo valve 20 is integrally formed on the rear portion of the input side portion of the input shaft 11, and the sleeve valve member 22 has inner and outer peripheral surfaces that are the outer peripheral surface of the rotor valve member 21 and the inner peripheral surface of the valve housing 10a, respectively. Are rotatably fitted to each other and are connected to the rear half 11a of the input shaft 11 by the engagement pins 23. The valve housing 10a is formed with four ports of the servo valve 20, namely, an input port 25, an exhaust port 26 and a pair of distribution ports 27a and 27b.

On the other hand, the power cylinder 30 has a rack bar 14
A cylinder 31 which is provided in the middle of the gear housing 10b and which is formed integrally with the gear housing 10b to coaxially and liquid-tightly penetrate the rack bar 14, and a cylinder 31 fixed to the rack bar 14 and liquid-tightly fitted to the inner periphery of the cylinder 31. Then, it is constituted by a piston 32 that divides the inside into left and right working chambers. The left and right working chambers are communicated with the respective distribution ports 27a and 27b of the servo valve 20 by communication passages, and the input port 2
5 and the discharge port 26 are connected to the supply pump 35 and the reservoir 36 by communication passages, respectively.

The servo valve 20 is a torsion bar 1 which is operated by a torque acting between the input shaft 11 and its rear half 11a.
5 is operated in response to a slight twist of the supply pump 35 to supply the working fluid from the supply pump 35 to each working chamber of the power cylinder 30 and to discharge the working fluid from each working chamber to the reservoir 36. It is controlled via 27a and 27b. As a result, steering assist force corresponding to the torque is applied to the front wheels via the rack bar 14. In addition,
Between the input shaft 11 and the latter half 11a thereof, both
Although a reaction force mechanism 29 for changing the power steering characteristic by changing the torsion spring characteristic between 1 and 11a is provided, the detailed structure is omitted. An oil seal 49 that seals between the reaction force mechanism 29 and the speed reduction mechanism 40 is provided between the outer periphery of the boss portion 11b and the bearing retainer that is liquid-tightly fixed to the valve housing 10a.

Next, the operation of the above embodiment will be described.

When the input shaft 11 rotates together with the steering wheel (both not shown) via the handle shaft, the rear half 11a also rotates together via the torsion bar 16, and the intermediate rotary member 38 moves to the input pinion 41 and the input pinion 41. The speed is reduced by the speed reduction mechanism 40 including the internal gear 42 and rotated. As the intermediate rotating member 38 rotates to the left or right from the front wheel steering neutral position shown in FIG. 2, the roller 48b of the protrusion 48 rolls radially outward along the cam groove 47, and the output shaft 13 is rotated. This rotation is converted into an axial movement of the rack bar 14 via the interlocking mechanism 15, and the front wheels are steered via a link (not shown). The output shaft 13 with respect to the rotation angle α of the intermediate rotation member 38 and the rotation angle β of the input shaft 11 connected to the steering wheel.
The rotation angle θ of is as follows.

[0020]

## EQU1 ## α = tan ^-1 (sin θ / (cos θ-r)) β = tan ^-1 (sin θ / (cos θ-r)) / g where r = e / R g: reduction ratio of reduction mechanism 40 intermediate rotation The reduction ratio between the member 38 and the output shaft 13 is the differential value dθ / dα of the above equation, and gradually decreases as the intermediate rotation member rotation angle α approaches 180 degrees away from the neutral position, and increases after that. . The characteristic of the steering gear ratio with respect to the steering wheel rotation angle β is the differential value dθ / dβ of the following equation.
3 in proportion to the speed reduction ratio g of the speed reduction mechanism 40. That is, the steering gear ratio is large at the steering neutral position, gradually decreases as the steering wheel rotation angle increases, reaches a minimum value at a predetermined steering wheel rotation angle position corresponding to the speed reduction ratio g, and a steering wheel rotation angle higher than that. Then, there is an increasing tendency, that is, the opposite characteristic. The steering wheel rotation angle position where the steering gear ratio is the minimum is 18 when the speed reduction ratio g of the speed reduction mechanism 40 is 1, as shown in the figure.
It is 0 degree, and increases as the reduction ratio g increases. FIG. 3 shows an example in which the speed reduction ratio g is changed when r = 0.4.
In this embodiment, the reduction ratio g of the reduction mechanism 40 is 1.4.
The characteristic at that time is shown by a solid line. In this case, the steering wheel rotation angle position at which the steering gear ratio is the minimum is 252 degrees, but the stopper does not steer more than 240 degrees.

During operation of the steering apparatus according to this embodiment, the load applied to the meshing portion of the reduction gear mechanism 40 increases as the transmission torque of the reduction gear mechanism 40 increases, but the input pinion 41 of the reduction gear mechanism 40 is increased.
Is also supported by the needle bearing 12a located on the opposite side of the bearings 17b and 17c to support both ends, so that the support rigidity increases and the deflection of the input pinion 41 due to the load applied during operation decreases, and the bearing 17b The load applied is also reduced. Therefore, it is possible to obtain a firm steering feeling and a good steering feeling, and since there is no problem in the meshing of the reduction mechanism 40, the operation is smooth and the durability is improved.

The input pinion 41 and the internal gear 42 are
The latter half 11a of the input shaft 11 and the intermediate rotating member 38, respectively.
Since the speed reducing mechanism 40 does not need to increase the number of parts because it is formed integrally with the speed reducing mechanism 40, since the speed reducing mechanism 40 effectively uses the space inside the intermediate rotation member 38, the volume of the front wheel steering device is reduced. A small increase is sufficient.

Next, in the second embodiment shown in FIG. 4, the extension shaft portion 12 is integrally formed with the boss portion 11b. The extension shaft 12 has a hole 38a formed in the center of the intermediate rotary member 38.
And, passing through the center hole 13a of the output shaft 13, its tip is supported by the tip member 10d at the rear end of the housing 10 via a needle bearing 12b. Also in this second embodiment,
Since the input pinion 41 is supported on both sides, the support rigidity increases and the deflection of the input pinion 41 due to the deflection added during operation is reduced, a good steering feeling with a firm response is obtained, and the operation becomes smooth and durable. Also improves.
Since other structures and operations are the same as those in the first embodiment,
Detailed description is omitted.

Although each of the above embodiments has shown an example in which a hydraulic power steering apparatus is used, the present invention uses another type of power steering apparatus, for example, an electric power steering apparatus. It can also be implemented. Further, the present invention can be applied to a front wheel steering device that uses other than the rack and pinion type such as the ball screw type and the worm pin type as the interlocking mechanism 15. Further, the invention can be applied not only to the front wheel steering device but also to the rear wheel steering device.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a first embodiment of a steering device according to the present invention.

2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a diagram showing an example of a steering gear ratio characteristic of the steering device according to the present invention.

FIG. 4 is an overall vertical sectional view of a second embodiment of the steering device according to the present invention.

FIG. 5 is a side view in which a main part of a steering device according to a conventional technique is cut away.

[Explanation of symbols]

10 ... Housing, 11 ... Input shaft, 12 ... Extension shaft part, 1
3 ... Output shaft, 14 ... Output operating member (rack bar), 15
... interlocking mechanism, 20 ... control device (servo valve), 30 ... booster device (power cylinder), 38 ... intermediate rotating member, 40 ...
Reduction mechanism, 41 ... Input pinion, 42 ... Internal gear, 45
... Steering characteristic imparting mechanism, 47 ... Cam groove, 48 ... Protrusion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Niwa 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Renjo Kato 1-1-1, Asahi-cho, Kariya City, Aichi Toyota Koki Co., Ltd. In-house (72) Inventor Masanori Natsume 1-1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd.

Claims (3)

[Claims] 1. An input shaft that is connected to a steering handle and rotates together, an output operating member that is connected to the input shaft through an output shaft and an interlocking mechanism, and that steers a wheel through a steering link, and the output operating member. And a control device that is provided on the input shaft and that operates according to the torque applied to the input shaft to change the assist force applied to the output actuating member, and that supports these members. In a steering apparatus including a housing, an intermediate rotating member eccentrically supported by the housing between the input shaft and the output shaft arranged coaxially with each other, and the intermediate rotation of the input shaft. An input pinion integrally provided on the end portion on the member side and an internal gear integrally provided on the intermediate rotation member and meshing with the input pinion, and the input shaft Reduction mechanism for decelerating the rotation of the intermediate rotation member and transmitting it to the intermediate rotation member, a cam groove formed in a diameter direction on one of the end surfaces of the intermediate rotation member and the output shaft facing each other, and the end surfaces of the opposite end surfaces facing each other. On the other hand, it consists of a protrusion that is eccentric from the center of rotation and protrudes in the axial direction and that engages in the cam groove, and the reduction ratio gradually decreases as the rotation angle of the input shaft from the steering neutral position increases. And a steering characteristic imparting mechanism for transmitting the rotation of the intermediate rotating member to the output shaft while integrally and coaxially formed at the output shaft side end portion of the input shaft and passing through the intermediate rotating member to output the output. A steering apparatus comprising: an extension shaft portion that extends axially and is rotatably supported by the housing. 2. The steering apparatus according to claim 1, wherein the extension shaft portion is supported by the housing via the output shaft. 3. The steering apparatus according to claim 1, wherein the extension shaft portion is directly supported by the housing.