JPH0423107Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a front wheel steering device for a front and rear wheel steered vehicle.
In particular, the movement of the front wheel steering link mechanism comprising a first pinion rotated by the steering wheel and a rack pushed in the axial direction by the rotation of the first pinion is controlled by the movement of the front wheel steering link mechanism. The transmission is transmitted to the rear wheel steering mechanism via a second pinion disposed at a predetermined displacement in the axial direction of the rack and rotated by the rack, and a connecting shaft connected to the second pinion and extending toward the rear of the vehicle. The present invention relates to a front wheel steering device for a front and rear wheel steered vehicle, that is, a rack and pinion type front wheel steering device.

[Prior art]

A conventional technique employing a rack and pinion type front wheel steering device for a front and rear wheel steered vehicle is disclosed in, for example, Japanese Patent Application Laid-open No. 122256/1983.

In the front wheel steering device disclosed in the same publication, a rack guide is provided at the meshing portion between the rack and each pinion to elastically urge the rack toward each pinion and to support the rack so as to be slidable in the axial direction. are provided for each.

[Problem that the invention attempts to solve]

Therefore, the rack moves in the axial direction against the sliding resistance of the two rack guides.
There is a risk of worsening the rudder return operation (restoration after turning the steering wheel without operating the steering wheel). Furthermore, since two rack guides are used, an increase in the number of parts and the number of assembly steps are unavoidable, resulting in an increase in cost.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problem, and in the above-mentioned front and rear wheel steered vehicle, an angle formed in the circumferential direction of the rack by the axes of the pinions is formed at a substantially central portion between the two pinions. a single rack guide that is assembled so as to be slidable in a direction approximately half of the axis of the rack, elastically urges the rack toward the meshing portion with both pinions, and supports the rack so as to be slidable in the axial direction thereof; It is distinctive in its placement.

[Functions and effects of the idea]

In this invention, as described above, a single rack guide is used to perform the same function as the conventional two rack guides, so the sliding resistance caused by the rack guides can be reduced, and the return of the rudder is reduced. The operation can be improved, and the number of parts can be reduced to reduce costs. Furthermore, in the present invention, the rack guide is assembled so as to be able to slide in a direction approximately half of the angle formed in the circumferential direction of the rack by the axes of both pinions at approximately the center between both pinions. The rack is elastically urged toward the meshing portions with both pinions with substantially equal force, and the meshing relationship at both meshing portions can be made uniform and optimal.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 schematically shows a front and rear wheel steered vehicle equipped with a front wheel steering device according to the present invention.
3) is pushed in its axial direction (horizontal direction), and the movement of the rack 22 in the axial direction causes the second pinion 23 to rotate. Note that, as is well known, each knuckle arm 25 is connected to both ends of the rack 22 via each tie rod 24, so that each front wheel WF is steered left and right by the axial movement of the rack 22. Further, a rear wheel steering device is connected to the second pinion 23 via a connecting shaft 30 that extends toward the rear of the vehicle. The rear wheel steering device is disclosed in Japanese Patent Application No. 60-240945 (Japanese Patent Application No. 62-99263).
It is the same as the one proposed in No. 1), and is composed of a coupling mechanism 40 and a steering link mechanism 50 for the rear wheels, but its detailed configuration and operation are omitted as they are considered unnecessary for the present invention. .

As shown in FIG. 2, the first pinion 21 is fitted with a pair of angular bearings B1 and B in a housing 60 that is assembled to a part of the vehicle body (not shown).
The inner end 2 is rotatably assembled via the inner end 2.
1a meshes with the first tooth portion 22a of the rack 22. The outer end 21b of the first pinion 21 connected to the steering wheel 10 is connected to an oil seal fitted into a cap 61 (fixed by a lock nut 62) that abuts and positions the outer race of the angular bearing B1. 63
It protrudes out of the housing 60 through.

The rack 22 has two ends (A and B in FIG. 1).
The first pinion is slidably supported in the housing 60 in the axial direction at a portion) and meshes with the first pinion 21.
A second tooth portion (not shown) that meshes with the tooth portion 22a and the second pinion 23 is provided. 2nd pinion 23
As shown in FIG. 3, the first pinion 21
The second
Similar to the first pinion 21 shown in the figure, it is rotatably assembled to the housing 60 via a pair of angular bearings, and the rack 22 is attached at the inner end.
It meshes with the second tooth part of. Note that the outer end 23b of the second pinion 23 connected to the connecting shaft 30
is the cap 64 (lock nut 6) that contacts and positions the outer race of the angular bearing.
5) protrudes outside the housing 60 through an oil seal fitted to the housing 60.

In this embodiment, as shown in FIGS. 1 and 2, a single rack guide 70 is disposed approximately in the center between the pinions 21 and 23. The rack guide 70 is connected to the housing 60.
The rack 22 is assembled to be slidable in a direction inclined by θ/2 with respect to the axis of each pinion 21, 23, and is biased by a compression spring 71 to move the rack 22 into the meshing portion with both pinions 21, 23. It is elastically biased with a substantially uniform force and supported so as to be slidable in its axial direction. Note that the elastic force of the compression spring 71 is exerted by the cap 66 screwed onto the housing 60.
(fixed by a lock nut 67) can be adjusted by screwing it forward and backward.

In this way, in this embodiment, the single rack guide 70 described above is designed to perform the same function as the two conventional rack guides (provided for each pinion 21, 23). Because of this, Rack Guide 70 of Rack 22
It is possible to reduce the sliding resistance caused by this, improving the return operation of the rudder, and also reducing the number of parts, thereby reducing costs. Furthermore, in this embodiment, the rack guide 70
is assembled so that it can slide in the direction of approximately half of the angle (θ) formed in the circumferential direction of the rack 22 by the axes of the pinions 21 and 23 at approximately the center between the pinions 21 and 23. Easy 2
2 is elastically urged toward the meshing portions with both pinions 21 and 23 with substantially equal force, and the meshing relationship at both the meshing portions can be made uniform and optimal.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a front and rear wheel steered vehicle equipped with a front wheel steering device according to the present invention, and FIG.
An enlarged sectional view along the line, Figure 3 is - of Figure 1.
FIG. 3 is an enlarged cross-sectional view taken along the line. Explanation of symbols, 10...Steering wheel,
21...1st pinion, 22...Rack, 22a
...First tooth portion, 23...Second pinion, 30...
Connection shaft, 60...Housing, 70...Rack guide, 71...Spring.

Claims (1)

[Scope of utility model registration request] The first rotated by the steering wheel
The movement of the front wheel steering link mechanism, which includes a pinion and a rack that is pushed in the axial direction by the rotation of the first pinion, is displaced from the first pinion by a predetermined amount in the axial direction of the rack. In the front and rear wheel steered vehicle, the transmission is transmitted to the rear wheel steering mechanism via a second pinion that is provided and rotated by the rack, and a connecting shaft that is coupled to the second pinion and extends rearward of the vehicle. The rack is assembled to a substantially central portion thereof so as to be slidable in a direction approximately half of the angle formed in the circumferential direction of the rack by the axes of the pinions, and the rack is directed toward the meshing portion with the pinions. A front wheel steering device for a front and rear wheel steered vehicle, characterized in that a single rack guide is provided that is elastically biased and slidably supported in the axial direction.