JP2974029B2 - Mounting method of piston cap in power steering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a piston cap in a power steering apparatus for mounting a piston cap for closing a through hole of a piston in an integral type power steering apparatus. .

(Prior Art) FIG. 4 shows a conventional general integral type power steering apparatus. In this power steering apparatus, by moving axially a piston 1, which is furnished to the cylinder housing H ₁ by the hydraulic force of the hydraulic fluid (arrow a, b directions), in mesh with the rack 2 parts of the piston 1 By rotating the sector gear 3, a wheel (not shown) is steered in the left-right direction.

In this case, the piston 1 is connected to the cylinder housing H ₁
In the switching of the rotary valve (not shown) that is furnished to continuously provided by valve housing H _2, one of the oil discharged from the pump (not shown) the cylinder housing H ₁ in the piston 1 the left and right pressure chambers 4, 5 which are partitioned by To the left (in the direction of arrow a) or to the right (in the direction of arrow b).

When the discharge oil of the pump is supplied to the left pressure chamber 4,
The piston 1 moves to the right. At this time, the hydraulic oil in the right pressure chamber 5 is returned to the tank (not shown), and the sector gear 3 rotates clockwise. On the other hand, when the pump discharge oil is supplied to the right pressure chamber 5, the piston 1 moves to the left. At this time, the hydraulic oil in the left pressure chamber 4 is returned into the tank, and the sector gear 3 rotates counterclockwise.

The rotary valve rotates in conjunction with the rotation of the stub shaft 6 which is rotated by rotating a handle (not shown). In this case, the spool of the rotary valve rotates integrally with the stub shaft 6, and the sleeve of the rotary valve rotates integrally with the worm shaft 9 screwed into the thread groove 8 of the through hole 7 formed in the axis of the piston 1. ing.
And the stub shaft 6 and the worm shaft 9
The worm shaft 9 is connected by a torsion bar 11 that is inserted through a through hole 10 formed in the axis of the worm shaft 9.

Therefore, when the handle is rotated rightward or leftward, the stub shaft 6 is rotated accordingly, and the spool of the rotary valve is rotated. The discharge oil of the pump by the rotation of the spool is supplied to one of the pressure chambers 5 of the pressure chamber 4 or the right side of the left side of the valve housing H _1. When the ejection oil pressure chamber is supplied to the piston 1 moves within the valve housing H ₁ to leftward or rightward. Due to the movement of the piston 1, the worm shaft 9 rotates, and accordingly, the sleeve of the rotary valve rotates integrally while maintaining the rotation angle relative to the spool.

Incidentally, in the steering apparatus such integral type, the axis of the piston 1, which partitions the pressure chamber 5 of the pressure chamber 4 and the right of the left side of the valve housing H _1, a worm shaft 9 fitted Through hole 7 for
Are formed. Therefore, a piston cap 12 for closing the through hole 7 is provided at one end of the piston 1. This is because when the left and right pressure chambers 4 and 5 communicate with each other via the through hole 7, the piston 1 does not have a function as a partition.

The piston cap 12 having the function as the partition is required to be able to withstand the hydraulic thrust of the left and right pressure chambers 4 and 5 and to have high oil tightness.

The conventional piston cap shown in FIG.
Reference numeral 12 denotes a plug type screwed into the through hole 7 of the piston 1. That is, a male screw 14 formed in the through hole 7 of the piston 1 and screwed into the screw 13, and a tapered surface 16 that contacts a tapered surface 15 formed at the end of the through hole 7 of the piston 1.
And a structure having: Such a piston cap 12 is mounted on the piston 1 by screwing its male screw 14 into the female screw 13 of the through hole 7 and bringing the tapered surface 16 into contact with the tapered surface 15 of the through hole 7 at a predetermined pressure. You.

In this case, a fixing force (prevention force) against the hydraulic thrust of the left and right pressure chambers 4 and 5 is provided at the threaded portion between the male screw 14 and the female screw 13, and the contact force between the tapered surface 16 and the tapered surface 15 is provided. , A metal seal function is provided to partition the communication between the left pressure chamber 4 and the right pressure chamber 5. Here, the tapered surfaces 15 and 16 are processed with high precision, and the external thread 14 and the internal thread 13 are used.
An adhesive for preventing the screw from being loosened is applied to the screwed portion with the screw.

(Problems to be Solved by the Present Invention) In the above-mentioned conventional piston cap, high oil tightness is obtained at the contact portion between the tapered surface 16 and the tapered surface 15, so that the through hole 7 of the piston 1 can be reliably closed. At the same time, the screw portion of the male screw 14 and the female screw 13 is securely fixed to the piston 1 without being affected by the hydraulic thrust of the left and right pressure chambers 4 and 5.

However, since such a conventional piston cap 12 is mounted on the piston 1 by screwing, not only the assemblability is inferior, but also both the piston cap 12 and the piston 1 are threaded (male thread 14 and female thread 13). High-precision taper processing (tapered surfaces 16 and 15) must be performed, and there has been a problem that the cost is increased.

An object of the present invention is to attach a piston cap to a piston by a simple operation of inserting a piston cap into a through hole formed in the axis of the piston and applying a predetermined pushing force, and to both the piston cap and the piston. It is an object of the present invention to provide a method of mounting a piston cap in a power steering device which does not require complicated processing and can obtain high oil tightness and fixing force on the piston cap.

(Means for Solving the Problems) The present invention presupposes a method for mounting a piston cap in a power steering device in which a piston cap is inserted into a through hole formed in the axis of the piston.

And, while assuming the mounting method described above, the present invention forms a tapered surface that expands toward the front end inside the front end of the cap, while forming an annular groove in the radial direction of the through hole, A guide portion that protrudes in the axial direction from the insertion trajectory of the cap at the opening edge of the annular groove and on the front side in the insertion direction of the cap, and when the cap is inserted, the tapered surface is guided by the guide portion,
It is characterized in that it is fitted in the annular groove while expanding the tip of the cap.

(Operation of the Present Invention) According to this configuration, the piston cap can be attached to the piston by a simple operation of inserting the piston cap into the through hole of the piston and applying a predetermined pushing force. And in this case, since the tip of the piston cap which is plastically deformed by the pushing force and expanded in diameter is fitted into the annular groove of the through hole,
This portion provides the piston cap with high oil tightness and a fixing force opposing the hydraulic thrust.

(Embodiments of the present invention) Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the drawings.

FIG. 1 shows an integral type power steering apparatus to which the present invention is applied. In this power steering device, the same components as those of the above-described conventional power steering device are denoted by the same reference numerals, and description thereof will be omitted.

In this power steering device, a piston cap 17 attached to one end of the piston 1 is of a plug type inserted into the through hole 7 of the piston 1. The piston cap 17 is inserted into the through hole 7, and the tip 18, which is plastically deformed and expanded by the pushing force at that time, has an annular groove 19 formed to be inclined with respect to the axis in the radial direction of the through hole 7.
It is fitted inside.

In this case, as shown in FIG. 2 (a), the piston cap 17 has a structure in which only a tapered surface 20 inclined at a predetermined angle is formed on the inner peripheral portion of the distal end 18 of the cylindrical main body. I have. On the other hand, a portion 21 of the through hole 7 of the piston 1 into which the piston cap 17 is fitted is made larger in diameter than other portions,
The annular groove 19 is formed at the inner end of the large-diameter portion 21.

It should be noted that the first and second portions are located between the large diameter portion 21 and other portions.
As is clear from the figure, a step is formed. This step corresponds to the guide portion of the present invention. In other words, this step is formed at the opening edge of the annular groove 19 and at the front side in the cap insertion direction. It is also clear from the drawings that the step forms a guide portion projecting in the axial direction from the insertion locus of the cap.

The piston cap 17 is fitted into the large-diameter portion 21 without any backlash. Such a piston cap
17 is inserted into the large-diameter portion 21 of the through hole 7 from its tip 18 as shown in FIG. 2 (a). When a predetermined amount of pressure is applied to the large-diameter portion 21 at the time of insertion into the large-diameter portion 21, the tapered surface 20 of the tip 18 abuts against the guide portion and is guided. As described above, the tip 18 is plastically deformed in the direction in which the diameter increases, and is fitted into the annular groove 19. The expansion of the tip 18 by plastic deformation is based on the same principle as that of plastic deformation by press molding, and the above-mentioned guide portion fulfills a die function.

Thus, the piston cap 17 can be easily and easily mounted on the piston 1 simply by inserting it into the large diameter portion 21 of the through hole 7 and applying a predetermined pushing force. The piston cap 17 attached to the piston 1 in this manner is plastically deformed by the pushing force and the tip 18 expanded in diameter.
Is fitted into the annular groove 19 formed at the inner end of the large-diameter portion 21, so that the fitting portion between the distal end 18 and the annular groove 19 has a metal sealing function and a retaining function, and is high. Oil tightness and a fixed force opposing the hydraulic thrust are obtained.

In the above embodiment, the portion 21 of the through hole 7 into which the piston cap 17 is inserted is set to have a large diameter, and the tip 18 of the piston cap 17 is pressed against the guide portion formed at the inner end of the large diameter portion 21 so that the tip 18 3 is plastically deformed in the direction in which the diameter of the piston is increased. As shown in FIG. 3, when the piston cap 17 is mounted in the through hole 7 of the piston 1, the jig 22 for diameter expansion is inserted into the through hole 7. The diameter of the distal end 18 may be expanded by the diameter expanding jig 22. In this case, the portion 23 of the through hole 7 into which the piston cap 17 is fitted can have the same diameter as the other portions, and the annular groove 19 can be perpendicular to the axis. The diameter-enlargement jig 22 has a cylindrical shape that is fitted into the through-hole 7 without play, and a tapered surface 24 for guide is formed on the outer peripheral portion at the tip. As shown in the figure, the taper surface 24 has an annular groove
Set it at a position opposite to 19. In this state, when the piston cap 17 is inserted into the through hole 7 and a predetermined amount of pressure is applied and pushed in when the piston cap 17 is inserted by a predetermined amount, the tapered surface 20 at the tip is guided by the tapered surface 24 of the jig 22 for diameter expansion. As a result, as shown in the figure, the tip 18 is plastically deformed in the direction in which the diameter increases, and is fitted into the annular groove 19.

Incidentally, in the embodiment of FIG.
Constitute the guide portion of the present invention.

(Effects of the Present Invention) As described above, according to the piston cap mounting method of the present invention, the piston cap is inserted into the through hole formed in the shaft center of the piston, and is plastically deformed by the pushing force at that time. The tip of the piston cap whose diameter has been enlarged is fitted into an annular groove formed in the radial direction of the through-hole, so that the piston cap only needs to be inserted into the through-hole of the piston to apply a predetermined pushing force. It can be attached to the piston with a simple operation.

In this case, the distal end of the piston cap whose diameter has been increased is fitted into the annular groove of the through-hole, so that the portion fitted to the annular groove at the distal end provides high oil tightness and a fixing force against hydraulic thrust. In addition, since there is no need to perform troublesome processing on both the piston cap and the piston, there are advantages such as cost reduction.

[Brief description of the drawings]

FIG. 1 is a sectional view of an integral type power steering apparatus to which the present invention is applied, and FIGS. 2 (a) and 2 (b).
FIG. 3 is an enlarged cross-sectional view illustrating a method of mounting a piston cap in the power steering apparatus, FIG. 3 is an enlarged cross-sectional view illustrating a mounting direction of a piston cap according to another embodiment, and FIG. 4 is a conventional integral type power steering. It is sectional drawing of an apparatus. 1 ... piston, 7 ... through-hole, 17 ... piston cap, 18 ... tip, 19 ... annular groove.

Claims (1)

(57) [Claims] 1. A method for mounting a piston cap in a power steering device in which a piston cap is inserted into a through hole formed in a shaft center of a piston, wherein a tapered surface that expands toward the tip is formed inside a tip of the cap. On the other hand, while forming an annular groove in the radial direction of the through hole, a guide portion that protrudes in the axial direction from the insertion trajectory of the cap is formed on the opening edge of the annular groove and on the front side in the insertion direction of the cap, A method of mounting a piston cap in a power steering device, wherein when a cap is inserted, a tapered surface thereof is guided by a guide portion and is fitted into an annular groove while expanding a tip of the cap.