JP2865964B2 - Detent mechanism for shaft member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft member detent mechanism for restricting relative rotation of a shaft member with respect to a housing.

[0002]

2. Description of the Related Art Conventionally, a shaft member rotatably held in a housing so that the shaft member slidably housed in the housing in the axial direction is prevented from rotating relative to the housing. As the mechanism, for example, a spline fitting or a key connection using a half-moon key is used. However, in spline fitting etc., due to the structure,
Some backlash occurs due to backlash or the like. Also, in order to allow the shaft member to slide in the axial direction,
A slight gap is required in the sliding portion, and this gap causes the shaft member to rattle in the circumferential direction. Furthermore, in long-term use, the above-mentioned rattling has further increased due to wear of the sliding portion.

[0003] On the other hand, in the above detent mechanism, the degree of rattling varies depending on the accuracy of individual components. If the play exceeds the permissible limit, the above play can be kept within the permissible limit by performing a so-called matching assembly in which parts that match each other are selected and combined. Adjustment is very time-consuming.

An object of the present invention is to provide a shaft member detent mechanism which can easily adjust the backlash of the shaft member.

[0005]

In order to achieve the above object, a rotation preventing mechanism for a shaft member according to the present invention is provided in a housing so as to be movable in an axial direction and a pair of flat surfaces substantially parallel to an outer periphery. Formed on the shaft member, a detent member made of a self-lubricating resin fitted to the flat surface of the shaft member while sandwiching the pair of flat surfaces of the shaft member, and the detent member formed on the housing. While fixing
A preload applying means for applying a required preload to the detent member in order to adjust a contact pressure of the detent member with respect to the flat surface of the shaft member is provided.

[0006]

According to the above-described shaft member detent mechanism,
Since the rotation preventing member is fitted to the flat surface of the shaft member, it is possible to prevent the shaft member from rattling in the circumferential direction. In addition, since the detent member is made of a resin having self-lubricating properties, even if it is fitted to the flat surface as described above, the smooth movement of the shaft member in the axial direction is not hindered.

Further, by applying a preload to the detent member by the preload applying means, it is possible to adjust the contact pressure of the detent member with respect to the flat surface of the shaft member. The degree of sticking, the frictional force against the axial movement of the shaft member, and the like can be easily adjusted. Furthermore, even if the detent member wears due to long-term use and a gap is generated between the detent member and the flat surface of the shaft member, the detent member is compressed and deformed by adjusting the preload applying means. The gap can be suppressed, and thereby the play can be adjusted.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a schematic configuration diagram of a rear wheel steering device including a shaft member detent mechanism A as one embodiment of the present invention. A conversion mechanism B for converting the rear wheel steering shaft 5 as an axial member into an axial movement for steering, and a connection mechanism C for connecting to a steering angle sensor for extracting the axial displacement of the rear wheel steering shaft 5 are provided. Contains. FIG. 3 is a cross-sectional view of a main part along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view showing the conversion mechanism B.

With reference to these figures, the conversion mechanism B
Is a worm 2 connected to the output shaft 1 of the motor M, and a worm wheel 3 whose outer teeth 3a mesh with the worm 2.
And the inner periphery of the worm wheel 3 and the annular fitting member 4
An annular female screw member 7 having a female screw portion 7a of a trapezoidal screw formed on the inner periphery thereof, and an annular male screw member 8 having an external thread portion 8a meshing with the female screw portion 7a formed on the outer periphery. And

Both ends of the outer periphery of the female screw member 7 are rotatably supported by the housing H by a pair of angular ball bearings 6. Accordingly, it is possible to prevent the female screw member 7 from rattling with respect to the housing H in the thrust direction. In addition, unnecessary bending of the female screw member 7 can be prevented, and thereby, occurrence of rotation transmission failure due to the trapezoidal screw biting due to the bending can be prevented.

The trapezoidal screw forming the female screw portion 7a and the male screw portion 8a is a JIS 30 ° lead 6 mm.
A trapezoidal screw can be exemplified. The male screw member 8 is keyed to the rear wheel steering shaft 5 by a half-moon key 9, thereby preventing the male screw member 8 from rotating relative to the rear wheel steering shaft 5. The snap ring 10 </ b> A and the caulking member 10 </ b> B which are fitted into the outer peripheral groove of the rear wheel steering shaft 5 and abut against each end of the male screw member 8 in the axial direction, respectively. The relative movement in the direction is prevented.

In the rear wheel steering device having the above-described conversion mechanism B, the rotational force of the motor M is controlled by the worm 2, worm wheel 3, fitting member 4, female screw member 7, and male screw member 8.
The transmission is transmitted to the rear wheel steering shaft 5 via the half-moon key 9 and the rear wheel is steered. Since the reverse efficiency is zero due to the trapezoidal screw mechanism of the female screw member 7 and the male screw member 8, even if an external force enters the rear wheel steering shaft 5 side in an emergency when the electric system or the like breaks down, the rear wheel does not It is held at the steering angle at the time. Accordingly, unnecessary sudden operation is not performed during traveling, which is more preferable in terms of fail-safe. Furthermore, since the conventional centering spring can be eliminated, the structure can be further simplified. Further, it is not necessary to unnecessarily increase the output of the motor against the centering spring.

The detent mechanism A will be described with reference to FIGS. 2, 5 and 7, which are sectional views taken along the line VII-VII of FIG. The detent mechanism A includes a pair of parallel flat surfaces 5a and 5b formed with a predetermined width in the axial direction on the outer periphery of the rear wheel steering shaft 5, and flat surfaces sandwiching both flat surfaces 5a and 5b. A detent member 11 having a substantially U-shaped cross section fitted to 5a, 5b, and screwed into a screw hole Hh of the housing H, and the detent member 11 is attached to inner surfaces Ha, Hb of the housing H.
And a screw member 12 as a preload applying means which is pushed and fixed in a state where the screw member is brought into contact with the flat surfaces 5a and 5b. And a lock nut 13 for regulating rotation of the housing 12 with respect to the housing H.

The detent member 11 is made of a self-lubricating resin such as oil-impregnated plastic. Therefore, even when the rotation preventing member 11 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, the rotation of the rear wheel steering shaft 5 is prevented. Allows smooth movement in the axial direction. The screw member 12 as the preload applying means is formed of an embedded plug having a screw portion 12a on the outer circumference and a wrench hole 12b on the end face for introducing and fitting a hexagon wrench.

By adjusting the screwing amount of the screw member 12, a preload is applied to the detent member 11, and the detent member 11 is moved between the inner surfaces Ha and Hb of the housing H and the rear wheel steering shaft 5.
Is compressed and deformed between the flat surfaces 5a and 5b, thereby making it possible to adjust the contact pressure of the rotation preventing member 11 to the flat surfaces 5a and 5b. When the anti-rotation mechanism A is incorporated, by setting the screwing position of the screw member 12 while measuring the torque on the rear wheel steering shaft 5 side or the worm 2 side, a desired preload, that is, a desired contact pressure can be easily adjusted. can do.

Referring to FIGS. 6 and 7, the mechanism C for connecting to the steering angle sensor will be described. The connection mechanism C is provided with a pin member C1 that is screwed upright on the peripheral surface of the rear wheel steering shaft 5 corresponding to the sensor connection hole Hs provided in the housing H, and a pin member C1 that is provided in the middle of the pin member C1. A hexagonal flange member C2 that is provided to lock the pin member C1 to the rear wheel steering shaft 5 by being pressed against the rear wheel steering shaft 5. A steering angle sensor (not shown) connected to the sensor connection hole Hs is connected to the pin member C1 and the pin member C
The swing lever includes a swing lever that swings with the displacement of 1. The steering angle is detected based on the swing angle of the swing lever.

According to this embodiment, the detent member 11
Is fitted to the flat surfaces 5a and 5b of the rear wheel steering shaft 5 with a predetermined contact pressure, so that the rattling of the rear wheel steering shaft 5 in the circumferential direction can be suppressed. Moreover, since the rotation preventing member 11 is made of a resin having self-lubricating properties, the axial movement of the rear wheel steering shaft 5 can be smoothly performed even if the rotation preventing member 11 is fitted as described above.

In particular, in the rear wheel steering device, when the rear wheel steering shaft 5 rattles in the circumferential direction, the axial stroke of the rear wheel steering shaft 5 is lost by the amount of the rattling, and the steering is accurately performed. You will not be able to do it. Moreover, in the rear wheel steering device, the required maximum steering angle is small, and therefore, the stroke of the rear wheel steering shaft 5 in the axial direction is, for example, 8 m.
Since it is as small as m, even if there is a little backlash, the steering is adversely affected. On the other hand, in the present embodiment, the above play can be suppressed, so that the steering amount can be accurately controlled.

Further, by adjusting the screwing position of the screw member 12, the rotation preventing member 11 is moved to the flat surface 5 of the rear wheel steering shaft 5.
a, 5b can be adjusted, whereby the degree of rattling in the circumferential direction of the rear wheel steering shaft 5, the frictional force against the axial movement of the rear wheel steering shaft 5, and the like can be adjusted. It can be easily adjusted. In addition, with long-term use,
Even if the portion of the detent member 11 that slides on the flat surfaces 5a, 5b wears out and a gap is generated between the detent member 11 and the flat surfaces 5a, 5b, the screw member 12 is tightened. Thereby, the rotation preventing member 11 can be compressed and deformed, the gap can be suppressed, and the play can be adjusted.

Further, since the above play can be suppressed, the detection accuracy of the mounted steering angle sensor can be improved. In particular, as described above, in the rear wheel steering device,
In the case where the stroke of the rear wheel steering shaft 5 in the axial direction is small, and the stroke of such a small stroke is large, the detection accuracy of the steering angle sensor is extremely deteriorated. In the example, since play can be suppressed, it is possible to avoid a decrease in accuracy of the steering angle sensor due to play.

The present invention is not limited to the above embodiment. For example, the flat surface 5
A recess 11A may be provided on the surface opposite to the surface in contact with a and 5b (see FIG. 8). In this case, the detent member 11
However, it can be easily deformed toward the flat surfaces 5a and 5b, and the play can be adjusted more easily. In addition, various design changes can be made without changing the gist of the present invention.

[0022]

As described above, according to the shaft member detent mechanism of the present invention, since the detent member is fitted on the flat surface of the shaft member, the rattling of the shaft member in the circumferential direction is suppressed. be able to. Further, since the detent member is made of a resin having self-lubricating properties, even if it is fitted on the flat surface as described above, the smooth movement of the shaft member in the axial direction is not hindered.

Further, by applying a preload to the detent member by the preload applying means, it is possible to adjust the contact pressure of the detent member with respect to the flat surface of the shaft member. It is possible to adjust the degree of sticking, the frictional force against the axial movement of the shaft member, and the like. Furthermore, even if the detent member wears due to long-term use and a gap is generated between the detent member and the flat surface of the shaft member, the detent member is compressed and deformed by adjusting the preload applying means. , The gap can be suppressed,
The play caused by the gap can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotation preventing mechanism for a shaft member according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of a rear wheel steering device to which a detent mechanism is applied.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a partially broken side view showing a conversion mechanism of the rear wheel steering device.

FIG. 5 is a plan view of a main part of a housing including a rotation stopping mechanism.

FIG. 6 is a side view of a main part of a housing including a rotation stopping mechanism and a coupling mechanism.

FIG. 7 is a cross-sectional view of a main part of a housing including a rotation stop mechanism and a connection mechanism.

FIG. 8 is a sectional view of a detent mechanism according to another embodiment of the present invention.

[Explanation of symbols]

 H Housing 5 Rear wheel steering shaft (shaft member) 5a, 5b Flat surface 11 Detent member 12 Screw member (preload applying means)

Claims (1)

(57) [Claims] A shaft member which is housed in the housing so as to be movable in the axial direction and has a pair of flat surfaces substantially parallel to an outer periphery thereof; and a flatness of the shaft member sandwiching the pair of flat surfaces of the shaft member. A detent member made of a self-lubricating resin fitted to a surface, and the detent member for fixing the detent member to the housing and adjusting a contact pressure of the detent member against a flat surface of the shaft member. A rotation preventing mechanism for a shaft member, comprising a preload applying means for applying a required preload to the member.