JP2006142845A - Outer box for hydraulic power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED To prevent nest leakage from occurring in an annular recess into which a seal member is incorporated.
A box body 6 is fitted into one end of a cylinder C, and a rack shaft 7 that moves integrally with the piston is supported by the box body 6. On the other hand, it is assumed that the outer box for hydraulic power steering is formed by forming the box body 6 by casting and forming annular recesses 10 and 16 for incorporating the seal member 9 on the sliding surface between the box body 6 and the rack shaft 7. To. While releasing one end of the said annular recessed parts 10 and 16 in the axial direction, the collar 12 which is a closure member which blocks the open end is press-fitted into the box body 6 on the open end side. Furthermore, the inner diameter of the press-fitting hole 11 into which the collar 12 is press-fitted is equal to or larger than the inner diameter of the annular recesses 10 and 16.
[Selection] Figure 1

Description

  The present invention relates to an outer box for hydraulic power steering for closing an end of a cylinder incorporating a piston.

A known outer box for this type of hydraulic power steering is shown in FIG. In the conventional outer box shown in FIG. 3, a box body 1 is fixed to one end of a cylinder c, and a rack shaft 2 is slidably passed through the box body 1. An annular groove 3 is formed on the inner periphery of the box body 1 thus configured, that is, on the contact surface side with the rack shaft 2, and a seal member 4 is incorporated in the annular groove 3. The bearing bush 5 is press-fitted.
JP-A-6-293272

  The conventional outer box for hydraulic power steering as described above is generally made of aluminum die casting. However, since the annular groove 3 is formed on the inner periphery of the box body 1, that is, on the contact surface side with the rack shaft 2, the core does not come off even if it is formed with a mold using the core. Therefore, only the annular groove 3 was cut while being integrally formed with a mold as a whole.

However, when cutting is performed on the box body 1 made of aluminum die casting, a casting nest may appear on the cut surface. In particular, the annular groove 3 needs a certain depth to incorporate the seal member 4, but the deeper the annular groove 3 is cut, the more the nest comes out on the cutting surface, which is the so-called There was a problem of causing nest leakage.
An object of the present invention is to provide an outer box for a hydraulic power steering in which a cutting allowance of an annular recess into which a seal member is incorporated is reduced and the nest leakage does not occur.

  In the present invention, the box body is fitted into one end of the power cylinder, and the rack body that moves integrally with the piston is supported by the box body. On the other hand, the box body is formed of a casting, In the outer box for hydraulic power steering in which an annular recess for incorporating a seal member is formed on the sliding surface side with the rack shaft, one end in the axial direction of the annular recess is released, and on the release end side, A feature is that the closing member for closing the release end is press-fitted into the box body, while the inner diameter of the press-fitting hole for press-fitting the closing member is equal to or larger than the inner diameter of the annular recess.

  According to the present invention, one end of the annular recess into which the seal member is incorporated is released, and the open end side is closed with the closing member, so that the annular recess can be integrally molded with the mold. Therefore, it is sufficient that the annular recess has a slight machining allowance, for example, a machining allowance of 0.3 mm or less, in order to process it to the final shape. Thus, it is sufficient to provide a slight cutting allowance, so that the casting nest in the box body does not surface. Therefore, the problem of so-called nest leakage does not occur.

  In the first embodiment shown in FIG. 1, a box body 6 is fixed to a cylinder C, and a rack shaft 7 having a piston (not shown) fixed thereto is slidably passed through the box body 6. A bearing bush 8 is press-fitted on the inner periphery of the box body 6 thus configured, that is, on the contact surface side with the rack shaft 7, and an annular recess for incorporating a seal member 9 at a position outside the bearing bush 8. 10 is formed.

  The annular recess 10 releases the end opposite to the bearing bush 8 and forms a press-fitting hole 11 continuous to the release end. A collar 12 which is a closing member of the present invention is press-fitted into the press-fitting hole 11 to close the release end of the annular recess 10. Note that the inner diameter of the inner peripheral surface 11 a of the press-fitting hole 11 is larger than the inner diameter of the inner peripheral surface 10 a of the annular recess 10, and a step portion 13 is formed at a continuous portion between the press-fitting hole 11 and the annular recess 10. I am doing so.

  As described above, the annular recess 10 and the press-fit hole 11 are made continuous, and the inner diameter of the inner peripheral surface 11a of the press-fit hole 11 is made larger than the inner diameter of the inner peripheral surface 10a of the annular recess 10, so that the above-described collar The mold can be pulled out in the direction of pulling out 12. In other words, the annular recess 10 and the press-fit hole 11 can be integrally formed with a mold.

  Further, when the collar 12 is firmly press-fitted to the step portion 13, the step portion 13 functions as a stopper for the collar 12. Therefore, the tip of the collar 12 can function as a stopper surface with respect to the rack shaft 7.

  In any case, according to the first embodiment, the annular recess 10 into which the seal member 9 is incorporated can be integrally formed with a mold, so that it is not necessary to cut the annular recess 10. Therefore, it is sufficient that the annular recess 10 has only a slight cutting allowance, for example, a cutting allowance of 0.3 mm or less, in order to process it to the final shape. Thus, since it is sufficient to provide a slight cutting allowance, the casting nest in the box body 1 does not surface. Therefore, the problem of so-called nest leakage does not occur.

  In the second embodiment shown in FIG. 2, a press-fitting hole 15 for press-fitting the bearing bush 14 is formed on the end surface of the box body 6 on the cylinder C side, and a seal member 9 is incorporated on the extension of the press-fitting hole 15. A recess 16 is formed. And the inside diameter of these press-fit holes 15 and the inside diameter of the annular recess 16 are made the same, and both are made continuous. Therefore, since the mold can be pulled out in the direction in which the bearing bush 14 is pulled out, the press-fitting hole 15 and the annular recess 16 can be integrally formed with the mold.

  In the first and second embodiments described above, one end of the annular recesses 10 and 16 is released, and the press-fitting holes 11 and 15 that are equal to or larger than the inner diameter of the annular recesses 10 and 16 are provided on the open end side. Since the closing member is press-fitted into the press-fitting holes 11 and 15, the mold can be removed from the press-fitting hole. Therefore, the box body 6 can be integrally formed with the mold, and the machining allowance of the annular recesses 10 and 16 can be minimized. Since the machining allowance is minimized as described above, the casting nest does not surface on the inner peripheral surfaces of the annular recesses 10 and 16, and no nest leakage occurs.

It is sectional drawing of the principal part of 1st Embodiment. It is sectional drawing of the principal part of 2nd Embodiment. It is principal part sectional drawing of the outer box for the conventional hydraulic type power steering.

Explanation of symbols

C Cylinder 6 Box body 7 Rack shaft 8 Bearing bush 9 Seal members 10 and 16 Annular recess 12 Collar 14 serving as a closing member Bearing bush serving also as a closing member

Claims (4)

  The box body is fitted to one end of the cylinder, and the box body is configured to support a rack shaft that moves integrally with the piston. On the other hand, the box body is formed of a casting. In the outer box for a hydraulic power steering formed with an annular recess for incorporating a seal member on the sliding surface side, one end in the axial direction of the annular recess is released, and the release end is connected to the release end side. An outer box for hydraulic power steering in which a closing member is press-fitted into a box body, and an inner diameter of a press-fitting hole into which the closing member is press-fitted is equal to or larger than an inner diameter of an annular recess.   2. The outer box for hydraulic power steering according to claim 1, wherein the annular recess releases the end opposite to the cylinder and is press-fitted into a box body with a collar as a closing member for closing the annular recess.   The outer box for a hydraulic power steering according to claim 2, wherein the end portion of the collar is a stopper surface for restricting the stroke of the rack shaft.   2. The outer box for hydraulic power steering according to claim 1, wherein the annular recess releases the end portion on the cylinder side and press-fits a bearing bush serving also as a closing member on the release end side.

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