JPH11198827A - Rack stopper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rack stopper which allows omission of manufacturing process and has a high dimensional accuracy in the inside diameter of a bushing. SOLUTION: A bushing 13 is formed through injection molding using a rack stopper body 12 as one part of a die, and is fixed at the same time as the molding process. The first 17 and the second ring-shaped recess 18 for accommodating the bushing 13 are formed on the inside surface 16 of the stopper body 12. The bore of the bushing 13 is decided by the dimensions of the die, and a high accuracy is secured for the bore of bushing 13. This allows omission of the fit-in operation of bushing 13 after being molded, so that the man-hours can be reduced and the manufacturing costs can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack-and-pinion type steering device, and more particularly to a rack stopper for slidably supporting a rack shaft in a rack stopper.

[0002]

2. Description of the Related Art In a rack and pinion type steering apparatus, a bush made of synthetic resin is interposed between a rack shaft that meshes with a pinion and a cylindrical rack stopper body through which the rack shaft is inserted. Is known in which the clearance of the rack shaft is kept substantially zero to prevent rattling noise of the rack shaft when sliding.

As an example of this, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 5439, an annular groove is provided on the inner peripheral surface of the rack stopper main body, and the bush is fixed to the rack stopper main body by the projection provided on the bush engaging with the annular groove. There are things that are. Normally, a synthetic resin bush is injection molded with a predetermined mold,
The bush after molding is fitted into the rack stopper main body to be mounted on the rack stopper main body.

[0004]

However, since the inner diameter of the bush mounted after molding is determined by both the inner diameter of the rack stopper body and the thickness of the bush, the inner diameter of the bush after mounting is highly accurate. Couldn't have wanted. Therefore, it was not possible to sufficiently prevent rattle of the rack shaft.

Therefore, it is conceivable to secure the accuracy of the inner diameter of the bush by shaping the inner diameter of the bush slightly beforehand and shaping the inner circumference after inserting the bush into the rack stopper body. In such a case, it takes time and effort after the bush is formed, which increases the manufacturing cost. The present invention has been made in view of the above problems, and has as its object to provide a rack stopper that can omit a manufacturing process and has high dimensional accuracy of the inner diameter of a bush.

[0006]

In order to achieve the above object, the invention according to claim 1 is applied to a rack-and-pinion type steering device, in which a rack shaft is brought into contact with a member that moves together with the rack shaft. A rack stopper body having an insertion hole through which the rack shaft is inserted, and a rack stopper body that is integrally fixed to the inner peripheral surface of the rack stopper body by injection molding and slides the rack shaft. A rack stopper comprising a resin bush.

In the above configuration, since the bush is fixed integrally with the rack stopper body by injection molding, the inner diameter of the bush is determined by the size of the injection molding die. As a result, the dimensional accuracy of the inner diameter of the bush is determined. Can be kept high. Therefore, it is possible to more reliably prevent rattling noise during sliding and damage to the rack shaft. Also,
The dimensional accuracy of the inner peripheral surface of the rack stopper body to which the bush is fixed does not need to be set strictly as in the related art. Further, the step of inserting the bush into the rack stopper main body, which has been conventionally performed, can be omitted.

The rack stopper according to the second aspect of the present invention
2. The rack stopper body according to claim 1, wherein a recess is formed in an inner peripheral surface of the rack stopper main body, and the bush is formed integrally with the cylindrical bush main body and radially outward from the bush main body inner peripheral surface. And a protrusion for preventing the fitting from being fitted into the concave portion.

The above arrangement has the following operation in addition to the operation of the first aspect of the invention. Conventionally, it is necessary to insert a protrusion for retaining into a groove or the like on the inner peripheral surface of the rack stopper body.In the conventional case, if the protrusion amount of the protrusion is large, it is difficult to fit into the groove or the like. Therefore, it is very difficult to set the amount of protrusion. In contrast, in the present invention,
Since the protrusion is formed in a form fitted in the groove or the like, the work of fitting is unnecessary, so that the protrusion amount of the protrusion can be easily set in consideration of only the difficulty of removal. As a result, a bush that is harder to pull out can be realized.

[0010] The rack stopper according to the third aspect of the present invention,
3. The rack stopper body according to claim 2, wherein the rack stopper body is made of a sintered product, the protrusion includes a pair of protrusions formed at both ends in the axial direction of the bush body, and the recess engages the pair of protrusions. And a pair of recesses which are open in opposite directions in the axial direction.

The above arrangement has the following effect in addition to the effect of the second aspect of the invention. Since the recess includes a pair of steps that are opened in opposite directions in the axial direction, the recess can be formed by a mold at the same time as the molding before sintering of the rack stopper body, and thereafter, the die can be removed in the axial direction. It is possible. This eliminates the necessity of forming a groove on the inner peripheral surface of the rack stopper body, which has been conventionally performed, thereby reducing man-hours as compared with the conventional method.

Further, the projections at both ends of the bush are engaged with the steps which are opened in opposite directions to each other, so that the bush is prevented from coming off in both directions. A rack stopper according to a fourth aspect of the present invention is the rack stopper according to the second aspect, further comprising an oil seal fitted to the rack stopper body adjacent to the bush, wherein the rack stopper body is made of a sintered product, and Includes a protrusion formed at one end in the axial direction of the bush main body, the recess includes a recess that engages the protrusion, and the recess includes a step that opens toward the oil seal side. It is assumed that.

The above arrangement has the following effect in addition to the effect of the second aspect of the invention. The protrusion at one end of the bush body is sandwiched between the step portion and the oil seal, so that the bush is prevented from falling off in both directions. In addition, if the recess is a stepped portion that opens toward the oil seal side, the rack stopper body can be molded by a mold at the same time as the molding before sintering, and the mold can be removed in the axial direction. As a result, it is not necessary to form a groove on the inner peripheral surface of the rack stopper main body, which is conventionally performed, so that the number of steps can be reduced as compared with the conventional method.

Further, the bush, the rack stopper main body, and the oil seal can be handled as one unit, which facilitates the work of incorporating the rack stopper into the steering device.

[0015]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a part of a rack and pinion type steering device. Referring to FIG. 1, in a rack and pinion type steering device 1, a tie rod 2 linked to a steered wheel via a knuckle arm and a rack shaft 3 linked to a steering wheel are linked by a ball joint 4. ing.

A rack is formed on the surface of the rack shaft 3, and in the housing 5, the rack meshes with a pinion connected to and linked with a steering wheel to form a gear device. As a result, the steered wheels are steered by the axial movement of the rack shaft 3 by the handle operation. A ball joint 4 is connected to an end of the rack shaft 3. The ball joint 4 includes a joint housing 6 and a ball. The joint housing 6 moves together with the rack shaft 3 that slides.

The housing 5 includes the steering device 1
And has a substantially cylindrical shape, and the rack shaft 3 is slidably inserted into the housing 5. Reference numeral 9 denotes a boot made of an elastic material, which covers a region from an end of the housing 5 to an intermediate portion of the tie rod 2. Reference numeral 10 denotes a rack stopper that is fixed to an end of the housing 5 and regulates a stroke amount of the rack shaft 3. When sliding the rack shaft 3 into the housing 5, the stroke amount of the rack shaft 3 is regulated by the contact of the moving joint housing 6 of the ball joint 4 with the stopper surface 11 of the rack stopper 10.

FIG. 2 is a sectional view of the rack stopper according to the present invention. Referring to FIG. 2, rack stopper 10 has a substantially cylindrical shape, and includes rack stopper body 12 and bush 13. The bush 13 is made of a synthetic resin and includes a cylindrical bush main body 14 and an annular protrusion 15 formed at the left end of the bush main body 14 in FIG. 2 and protruding radially outward.

On the other hand, the inner peripheral surface 1 of the rack stopper body 12
6 includes a first and a second for accommodating the bush 13.
Annular concave portions 17 and 18 are formed. The first annular recess 17 extends from the stopper surface 11 of the rack stopper main body 12 to an intermediate portion in the axial direction, and has a groove bottom diameter larger than the inner diameter of the first annular recess 17. It is continuous to 18. The bush body 14 is accommodated in the first annular recess 17, and the annular projection 15 is accommodated in the second annular recess 18. Bush 1
The bush 13 is prevented from coming off in both axial directions with respect to the rack stopper main body 12 in a state where the third annular projection 15 is in contact with the side wall surfaces 18a, 18b on both sides of the second annular recess 18. In the present embodiment, the axial width of the second annular concave portion 18 composed of an annular groove is about 1 mm, and the radial depth is about 1 mm.

On the other hand, an annular recess 22 is formed at the left end of the rack stopper body 12 in FIG. The annular recess 22 accommodates an oil seal (not shown). A retaining ring 25 for fixing the rack stopper main body 12 to the inner surface of the housing 5 is provided on the outer peripheral surface 23 of the rack stopper main body 12.
Is formed in a circumferential groove 26 having a semicircular cross section for accommodating the same.
The stopper surface 11 of the rack stopper main body 12 contacts the joint housing 6 to regulate the stroke of the rack shaft 3.

Bush 13 having annular projection 15
Can be inserted into the rack stopper body 12 by inserting a core mold corresponding to the rack shaft 3 into the rack stopper body 12.
Is injection molded as a part of a mold, and is fixed at the same time as molding. In this way, the clearance between the inner peripheral surface 28 of the bush 13 fixed to the inner peripheral surface 27 of the first annular concave portion 17 of the rack stopper main body 12 and the outer peripheral surface of the rack shaft 3 is substantially zero. In this state, the rack shaft 3 is slidably supported in the axial direction.

In the present embodiment, the following operational effects are obtained. That is, the bush 13 is formed by injection molding in the rack stopper main body 12, and the inner diameter of the bush 13 is defined by the dimension of the core mold. Therefore, the accuracy of the inner diameter of the bush 13 is high. Therefore, the rack shaft 3 can be supported without play. In addition, since the work of fitting the formed bush 13 as in the related art is not required, the manufacturing cost can be reduced by reducing the number of steps.

Further, since the annular projection 15 for retaining is engaged with the annular recess 18 of the rack stopper body 12 by injection molding, the work of fitting the formed projection as in the conventional case is taken into consideration. No need. Therefore, it is possible to provide the annular projection 15 suitable for retaining, for example, the annular projection 15 having a sufficiently large radially outwardly protruding amount. As a result, it is possible to realize the bush 13 which is hard to come off.

Next, another embodiment will be described. FIG. 3 is a sectional view of a rack stopper according to another embodiment of the present invention. Referring to FIG. 3, the bush 13 is injection-molded with the rack stopper main body 12 as a part of a mold, and is fixed at the same time as the molding, as in the first embodiment. The bush 13 includes a cylindrical bush body 14 and annular projections 30 and 31 formed at both ends of the bush body 14 and projecting radially outward.

The rack stopper body 12 has a pair of recesses 32, 33 for accommodating the annular projections 30, 31 at both ends of the inner peripheral surface 16, respectively. It includes a pair of annular steps 51, 52 that open in opposite axial directions. Each annular step 51,
The annular projections 30 and 31 respectively engage with 52. After the annular step portions 51 and 52 are formed by a mold at the same time as the molding before sintering the rack stopper main body 12, the rack stopper main body 12 is die-cut in the axial direction and then sintered.

The present embodiment has the following functions and effects in addition to the same functions and effects as those of the above embodiment. That is, in the rack stopper main body 12, since the pair of concave portions 32, 33 for accommodating the annular projections 30, 31 are open on both sides in the axial direction, the rack stopper main body 12 can be formed by a mold. Therefore, since it is not necessary to form an annular groove or the like for retaining the inner peripheral surface 16 by post-processing, the manufacturing cost can be reduced by reducing the number of steps.

The annular projections 3 at both ends of the bush 13
The engagement of the bush 13 with the annular step portions 51 and 52 prevents the bush 13 from falling off in both directions. Next, still another embodiment will be described. FIG.
FIG. 6 is a sectional view of another embodiment of the present invention. Referring to FIG. 4, in the present embodiment, rack stopper 10 includes an oil seal 35. The oil seal 35 has a known configuration, and includes a backup ring 36 made of sheet metal, a seal member 37, and a tightening ring 38.

On the other hand, as in the first embodiment, the bush 13 is injection-molded with the rack stopper body 12 as a part of a mold, and is fixed simultaneously with the molding. Bush 13
Is a cylindrical bush body 14 and the bush body 1
4 is provided at the left end in FIG. 4 and has an annular projection 15 as a projection protruding radially outward. First and second annular concave portions 39 and 40 for accommodating the bush 13 are provided on the inner peripheral surface 16 of the rack stopper body 12.
And a third annular concave portion 41 for accommodating the oil seal 35. The first annular recess 39 extends from the intermediate portion in the axial direction toward the left-hand direction shown in FIG. 4 and is continuous with the second annular recess 40 having an inner diameter larger than that of the first annular recess 39. Further, the second annular concave portion 40 is continuous with a third annular concave portion 41 having an inner diameter larger than that of the second annular concave portion 40. The second annular recess 40 includes an annular step 53 that opens toward the left side (toward the oil seal 35) shown in FIG.

The bush body 14 is accommodated in a first annular recess 39, and the annular projection 15 is accommodated in a second annular recess 40. As in the case of the second embodiment, after the second annular concave portion 40 is formed by a mold at the same time as the molding before the sintering of the rack stopper main body 12, the rack stopper main body 12 is die-cut in the axial direction. Then it is sintered.

The third annular recess 41 is formed so as to open to the left end of the rack stopper main body 12 in FIG. The oil seal 35 is press-fitted into the third annular recess 41 provided in the rack stopper main body 12, and is located at a position where the end face 42 (the right end face in FIG. 4) of the backup ring 36 of the oil seal 35 contacts the bush 13. Fixed. In this state, the annular projection 15 of the bush 13 is sandwiched between the annular step 53 and the oil seal 35.

In this embodiment, the following operation and effect can be obtained. The bush 13 is formed by injection molding in the rack stopper main body 12, and the inner diameter of the bush 13 is defined by the size of the mold. Therefore, the accuracy of the inner diameter of the bush 13 is high. Therefore, the rack shaft 3 can be supported without play.
That is, in the rack stopper main body 12, the annular protrusion 39
The rack stopper body 12 can be formed by a mold because the concave portion 40 for accommodating the rack stopper is open at one end in the axial direction. Therefore, since it is not necessary to form an annular groove or the like for retaining the inner peripheral surface 16 by post-processing, the manufacturing cost can be reduced by reducing the number of steps.

Further, since the annular projection 15 of the bush 13 is sandwiched between the annular step 53 and the oil seal 35, the bush 13 is prevented from coming off in both directions. The bush 13, the rack stopper body 12, and the oil seal 35 can be handled as one unit,
The work of incorporating the rack stopper 10 into the steering device becomes easy.

The oil seal 35 has a stepped outer diameter and is press-fitted into the third annular recess 41 and directly press-fitted into the housing 5, thereby omitting a seal member between the rack stopper 10 and the housing 5. be able to. In the above-described three embodiments, the annular projections 15, 30, and 31 provided on the bush 13 correspond to the rack stopper main body 12.
Annular recesses 18, 32, 33,
Although the configuration for fitting with 40 is shown, the present invention is not limited thereto, and a plurality of claw-shaped projections circumferentially arranged on the bush 13 are equally circumferentially arranged on the inner peripheral surface 16 of the rack stopper body 12. It may be configured to fit with a plurality of recesses.

It goes without saying that various modifications are possible within the scope of the claims of the present invention.

[0035]

According to the first aspect of the invention, since the bush is formed by injection molding in the rack stopper main body, the accuracy of the inner diameter of the bush is high. Therefore, the rack shaft can be supported without play. In addition, since the operation of fitting the bush is not required, the manufacturing cost can be reduced by reducing the number of steps.

According to the second aspect of the present invention, in addition to the effect of the first aspect, since the retaining projection is formed in a manner to be fitted into the concave portion of the rack stopper main body, the conventional structure is provided. There is no need to consider the work of fitting the protrusion after molding. Therefore, it becomes possible to provide a projection suitable for retaining, and as a result, it is possible to realize a bush that is difficult to remove.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect, if the recess is formed by a pair of steps which are opened in opposite directions to each other, the mold can be formed simultaneously with the molding before sintering. And can be formed without the need for post-processing as in the prior art.
Moreover, since the bush is injection-molded so as to engage the pair of projections at both ends in the axial direction of the bush body with each step,
A bush that is prevented from falling off in both directions can be realized.

According to the fourth aspect of the present invention, in addition to the effects of the first or second aspect, the protrusion at one end of the bush body is sandwiched between the step and the oil seal, so that both ends of the bush are provided. A directional retention is achieved. In addition, if the recess is a stepped portion that opens toward the oil seal side, the rack stopper body can be formed at the same time as the molding before sintering, and there is no need to perform post-processing as in the related art. Also, the rack stopper body, bush and oil seal can be handled as one unit,
The work of incorporating the rack stopper into the steering device becomes easy.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a steering device in which a rack stopper according to one embodiment of the present invention is disposed.

FIG. 2 is a sectional view of a rack stopper according to one embodiment of the present invention.

FIG. 3 is a sectional view of a rack stopper according to another embodiment of the present invention.

FIG. 4 is a sectional view of a rack stopper according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 steering device 3 rack shaft 5 housing 10 rack stopper 12 rack stopper body 13 bush 15 annular projection 18 second annular recess

Claims (4)

[Claims] 1. A rack stopper applied to a rack-and-pinion type steering device, which abuts on a member that moves with the rack shaft and regulates the axial position of the rack shaft, and has an insertion hole through which the rack shaft is inserted. A rack stopper, comprising: a rack stopper main body; and a synthetic resin bush that is integrally fixed to an inner peripheral surface of the rack stopper main body by injection molding and slides a rack shaft. 2. A recess is formed in an inner peripheral surface of the rack stopper main body, and the bush is formed integrally with the cylindrical bush main body and radially outward from the inner peripheral surface of the bush main body. 2. The rack stopper according to claim 1, further comprising: a projection for preventing the fitting from being inserted into the recess. 3. The rack stopper body is made of a sintered product, the projections include a pair of projections formed at both axial ends of the bush body, and the recesses engage the pair of projections, respectively. The rack stopper according to claim 2, further comprising a pair of recesses, wherein the pair of recesses include a pair of stepped portions that are opened in opposite axial directions. 4. An oil seal fitted to a rack stopper main body is provided adjacent to the bush, the rack stopper main body is made of a sintered product, and the projection is formed at one axial end of the bush main body. 3. A projection according to claim 2, wherein said recess includes a recess engaging said projection, and said recess includes a step which opens toward said oil seal. Rack stopper.