JP2978338B2 - Steering gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for steering wheels of an automobile or the like, and more particularly to a power source in which a steering gear ratio (steering wheel turning angle / tire turning angle) decreases with an increasing steering wheel turning angle. It relates to a steering device of the type.

[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, a worm pin type, and the like. Otherwise, the feeling of incision when the steering wheel is cut becomes insufficient, and the maximum steering wheel rotation angle required to obtain the desired maximum front wheel steering angle becomes large (for example, 540 degrees). If the steering gear ratio is reduced in order to solve this problem, the driver feels too much in the vicinity of the steering wheel neutral position.

In order to solve such a problem, the applicant has previously proposed a steering device according to Japanese Patent Application No. 3-240398. As shown in FIG. 5, an intermediate rotary member 2 and an output shaft 3 connected to an input shaft 1 are provided eccentrically by a predetermined amount, and a diametrical cam groove is provided between the two members. A steering characteristic imparting mechanism 4 comprising a projection 4b and a projection 4b engaged with the steering wheel 4a, whereby the steering gear ratio is increased according to an increase in the rotation angle of the input shaft 1 connected to the steering wheel from the neutral steering position. The above problem is solved by gradually decreasing the number. In this technique, the rotation angle of the intermediate rotation member 2 is limited to 180 degrees or less, but the rotation angle of the steering wheel is required to be 180 degrees or more (for example, 240 degrees). Rotating member 2
A speed reduction mechanism 5 composed of an input pinion 5a and an internal gear 5b is provided between the two. This is a hydraulic front-wheel power steering device that operates a power cylinder by a servo valve that operates according to a torque applied to the input shaft 1 to apply an assist force to an output operation member (rack bar).

[0004]

However, in this case, since the input pinion 5a of the speed reduction mechanism 5 is a cantilevered support that protrudes greatly from the bearing 6 supporting the input shaft 1, the transmission of the speed reduction mechanism 5 during operation is performed. When the torque increases, the input pinion 5a bends due to the load applied to the meshing portion, and the load on the bearing 6 increases. Therefore, the sense of rigidity of the steering decreases, the meshing of the speed reduction mechanism 5 is adversely affected, and the steering device smoothly moves. There is a problem that hinders the proper operation and lowers the durability. An object of the present invention is to solve such a problem and to obtain a steering device which can obtain a good steering feeling and a smooth operation, and has excellent durability.

[0005]

To this end, a steering apparatus according to the present invention comprises, as shown in FIGS. 1 to 4, an input shaft 11, which is connected to a steering wheel and rotates together, an output shaft 13, and an interlocking mechanism. An output operating member 14 that is connected to the input shaft 11 via a steering wheel 15 and steers wheels via a steering link; a booster 30 that applies an assist force to the output operating member;
A control device 20 is provided on the input shaft 11 and operates according to the torque applied thereto to change the assisting force applied by the booster 30 to the output operating member 14, and the housing 10 supporting these members. In the steering device, between the input shaft 11 and the output shaft 13 which are arranged coaxially with each other, the intermediate rotating member 38 eccentrically supported by the housing 10 and the intermediate shaft of the input shaft 11 An input pinion 41 provided integrally at the end of the rotating member 38 and an internal gear 42 provided integrally with the intermediate rotating member 38 and meshing with the input pinion 41 are provided to rotate the input shaft 11. A reduction mechanism 40 for reducing the speed and transmitting the intermediate rotation member 38 to the intermediate rotation member 38; 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
A steering characteristic imparting mechanism 45 for transmitting the rotation of the intermediate rotation member 38 to the output shaft 13 while gradually reducing the reduction ratio in accordance with an 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 formed integrally and coaxially 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). Is what you 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 that rotates together with the steering wheel is reduced by the reduction mechanism 40 and transmitted to the intermediate rotation member 38, and transmitted to the output shaft 13 via the steering characteristic imparting mechanism 45 including the cam groove 47 and the projection 48. And the interlocking mechanism 15
And the wheels are steered via the output operating member 14. At this time, the load applied to the meshing portion also increases with an increase in the transmission torque of the speed reduction mechanism 40, but the input pinion 41 of the speed reduction 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 is increased, the deflection of the input pinion 41 due to the load applied to the meshing portion is reduced, and the load applied to some bearings is not increased.

[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 speed reduction mechanism is reduced, and the load on the bearing is not increased. A responsive and good steering feeling can be obtained, and a steering device with smooth operation and excellent durability can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment shown in FIGS. 1 to 3 will be described below. As shown in FIG. 1, a housing 10 of the steering apparatus according to the present embodiment includes a valve housing
0a and a gear housing 10b.
Input shaft 11 and its rear half 1 arranged coaxially with each other
1a is a valve housing 10 via bearings 17a and 17b.
a and is connected by a torsion bar 16 so as to be elastically relatively rotatable.

On the rear side of the input shaft 11, an intermediate rotating member 38 is eccentrically supported in the gear housing 10b via two bearings 19, and the rotating shaft lines O1 and O2 of the two rotating shafts 11 and 38. The amount of eccentricity between is e. Input shaft 11
Boss portion 11b fixed to the rear portion of rear half portion 11a through key 11c and nut 50 and supported by bearing 17c
Is formed with an input pinion 41, and this input pinion 4
1 and an internal gear 42 formed coaxially with the front half of the intermediate rotating 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 rotating member 38. I have.

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

An extended shaft portion 12 formed coaxially and protruding rearward from the rear end of the rear half portion 11a of the input shaft 11 extends rearward through a hole 38a formed in the center of the intermediate rotating member 38. I have. The input shaft 11 and the output shaft 13 are coaxially arranged, and the tip of the extension shaft 12 is a needle bearing 12a.
And is supported by the output shaft 13.

1 and 2, the steering characteristic imparting mechanism 45 for transmitting the rotation of the intermediate rotation member 38 to the output shaft 13 while gradually reducing the reduction ratio in accordance with the increase in the rotation angle from the steering neutral position. Give an explanation. A cam groove 47 extending in the diametric direction is formed on the rear end face of the intermediate rotary member 38, and a projection 48 is provided on the front end face of the output flange 39 opposed thereto, by a distance R from the rotation axis O <b> 3 of the output shaft 13. It is provided so as to protrude axially from the center. This distance R is larger than the amount of eccentricity e between the rotation axes O2 and O3 of the members 38 and 13. The projection 48 includes a pin 48a implanted and 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 rollably engaged with substantially no gap. In this embodiment, the cam groove 47 of the steering characteristic imparting mechanism 45 is located on the intermediate rotation member 38 side, and the projection 48 is located on the output shaft 13.
On the other hand, the projection 48 is connected to the intermediate rotating member 38
A cam groove 47 may be provided on the output shaft 13 side.

As shown in FIG. 1, the front wheel steering device of the present embodiment is provided with a power steering device including a servo valve (control device) 20 and a power cylinder (power booster) 30. The rotor valve member 21 of the servo valve 20 is integrally formed at the rear 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 10 a, respectively. Are rotatably fitted to each other, and are connected to the rear half 11 a of the input shaft 11 by an engagement pin 23. Four ports of the servo valve 20, namely, an input port 25, a discharge port 26, and a pair of distribution ports 27a and 27b are formed in the valve housing 10a.

On the other hand, the power cylinder 30 is
And a cylinder 31 formed integrally with the gear housing 10b and penetrating the rack bar 14 coaxially and liquid-tightly, and fixed to the rack bar 14 and fitted liquid-tightly to the inner periphery of the cylinder 31. And a piston 32 that separates 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 paths, respectively.
5 and the discharge port 26 are connected to a supply pump 35 and a reservoir 36 by communication paths, respectively.

The servo valve 20 is provided with a torsion bar 1 by a torque acting between the input shaft 11 and its rear half 11a.
5 is actuated in response to slight twisting, and supply of working fluid from the supply pump 35 to each working chamber of the power cylinder 30 and discharge of working fluid from each working chamber to the reservoir 36 are performed by the respective distribution ports 25, 26,. The control is performed via 27a and 27b. As a result, a 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 its rear half 11a,
Although a reaction force mechanism 29 for changing the power steering characteristic by changing the torsion spring characteristic between the first and the 11a is provided, the detailed structure is omitted. An oil seal 49 for sealing between the reaction force mechanism 29 and the reduction mechanism 40 is provided between the outer periphery of the boss 11b and a bearing retainer fixed to the valve housing 10a in a liquid-tight manner.

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 portion 11a is also rotated via the torsion bar 16, and the intermediate rotating member 38 is driven by the input pinion 41 and the input pinion 41. The rotation is performed at a reduced speed by the reduction mechanism 40 including the internal gear 42. As the intermediate rotating member 38 rotates left or right from the front wheel steering neutral position shown in FIG. 2, the roller 48b of the projection 48 rolls radially outward along the cam groove 47, and the output shaft 13 is rotated. This rotation is converted into 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
Are respectively as follows.

[0020]

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. . Further, the characteristic of the steering gear ratio with respect to the steering wheel rotation angle β is represented by a differential value dθ / dβ in the following equation.
3 in accordance with the speed reduction ratio g of the speed reduction mechanism 40. That is, the steering gear ratio is large at the neutral steering position, gradually decreases with an increase in the steering wheel rotation angle, reaches a minimum value at a predetermined steering wheel rotation angle position corresponding to the reduction ratio g, and further exceeds the steering wheel rotation angle. In this case, the characteristics tend to increase, that is, the characteristics are reversed. As shown in the figure, the steering wheel rotation angle position at which the steering gear ratio becomes the minimum is 18 when the reduction ratio g of the reduction mechanism 40 is 1.
0 degree, and increases as the reduction ratio g increases. FIG. 3 shows an example in which the reduction ratio g is changed when r = 0.4.
In this embodiment, the speed reduction ratio g of the speed reduction mechanism 40 is 1.4,
The characteristics at that time are shown by solid lines. In this case, the steering wheel rotation angle position at which the steering gear ratio is minimum is 252 degrees, but the stopper does not steer more than 240 degrees.

In the operation of the steering system according to the present embodiment, the load applied to the meshing portion increases in accordance with the increase in the transmission torque of the speed reduction mechanism 40.
Is also supported by the needle bearing 12a located on the opposite side of the bearings 17b and 17c, and is supported at both ends. Therefore, the supporting rigidity is increased, and the deflection of the input pinion 41 due to the load applied during operation is reduced. The applied load is also reduced. Therefore, a good steering feeling with firm response can be obtained, and since there is no problem in the engagement of the speed reduction mechanism 40, the operation is smooth and the durability is improved.

The input pinion 41 and the internal gear 42 are
The rear half 11a of the input shaft 11 and the intermediate rotating member 38 are respectively provided.
, It is not necessary to increase the number of parts for the speed reduction mechanism 40. Further, since the speed reduction mechanism 40 effectively uses the space inside the intermediate rotation member 38, the volume of the front wheel steering device is reduced. The increase is small enough.

Next, in the second embodiment shown in FIG. 4, the extension shaft portion 12 is formed integrally with the boss portion 11b. The extension shaft 12 has a hole 38 a formed in the center of the intermediate rotating member 38.
The distal end of the output shaft 13 is supported by a distal end 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 at both ends, the support rigidity is increased, the deflection of the input pinion 41 due to the deflection applied during operation is reduced, and a good steering feeling with firm response is obtained, and the operation becomes smooth and the durability is improved. Also improve.
Since other structures and operations are the same as those of the first embodiment,
Detailed description is omitted.

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

[Brief description of the drawings]

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

FIG. 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 longitudinal 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 the steering device according to the prior art is broken.

[Explanation of symbols]

10 housing, 11 input shaft, 12 extension shaft, 1
3 ... output shaft, 14 ... output operation member (rack bar), 15
... Interlocking mechanism, 20 ... Control device (servo valve), 30 ... Power booster (power cylinder), 38 ... Intermediate rotating member, 40 ...
Reduction mechanism, 41: input pinion, 42: internal gear, 45
... A steering characteristic imparting mechanism, 47 a cam groove, 48 a projection.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoru Niwa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Yasuyoshi 1-1-1 Asahimachi, Kariya City, Aichi Prefecture Toyota Koki Co., Ltd. In-company (72) Inventor Masanori Natsume 1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Inside Toyota Koki Co., Ltd. (56) References JP-A-5-50924 (JP, A) JP-A-5-178222 (JP, A) JP-A-3-227772 (JP, A) JP-A-2-14971 (JP, A) JP-A-60-226365 (JP, A) JP-A-61-218481 (JP, A) Patent 2504231 (JP, A) , B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 5/06-5/22 B62D 3/12

Claims (3)

(57) [Claims] An input shaft connected to a steering wheel and rotating together; an output operating member connected to the input shaft via an output shaft and an interlocking mechanism to steer wheels via a steering link; A booster device that applies an assist force to the input shaft; a control device that is provided on the input shaft and that operates according to the torque applied thereto to change the assist force that the booster device applies to the output operating member; A steering device comprising a housing, an intermediate rotation member eccentrically supported between the input shaft and the output shaft and supported by the housing between the input shaft and the output shaft coaxially arranged with each other; and the intermediate rotation of the input shaft. The input shaft comprises an input pinion integrally provided at the member side end and an internal gear integrally provided with the intermediate rotating member and meshing with the input pinion. A speed reduction mechanism for reducing the rotation of the intermediate rotation member and transmitting the rotation to the intermediate rotation member; a cam groove formed in one of the opposed end surfaces of the intermediate rotation member and the output shaft in a diametrical direction; On the other hand, a projection is provided which is eccentric from the center of rotation and protrudes in the axial direction and is engaged with the cam groove. The reduction ratio gradually decreases in accordance with an increase in the rotation angle of the input shaft from the steering neutral position. A steering characteristic imparting mechanism for transmitting the rotation of the intermediate rotation member to the output shaft while causing the output shaft to pass through the intermediate rotation member and formed integrally and coaxially with the output shaft side end of the input shaft. A steering device, comprising: an extension shaft extending to the shaft side and rotatably supported by the housing. 2. The steering device according to claim 1, wherein the extension shaft portion is supported by the housing via the output shaft. 3. The steering device according to claim 1, wherein the extension shaft portion is directly supported by the housing.