JP2546804Y2 - Integral type power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integral type power steering device.

[0002]

2. Description of the Related Art In general, in a power steering apparatus, the inside of a cylinder is divided into two pressure chambers by a piston slidably fitted in the cylinder, and a pressure fluid switched and controlled by a control valve is introduced into one of the two pressure chambers. A piston is actuated by a pressure difference between the two chambers to apply an assisting force in the steering direction.

In such a power steering device,
In order to protect the steering link system, a stroke limiter is provided to limit the stroke of the piston after reaching a required steering angle.

[0004] As a stroke limiter of a conventional integral type power steering device, a tooth formed on a tooth surface of a sector gear is abutted at an extreme position where a rack formed on a piston and a sector gear which rotates forward and backward with the reciprocation of the piston mesh. There is known a device provided with a stopper for stopping the motor. This stopper is usually composed of a stopper bolt screwed into a screw hole formed in the housing while maintaining the liquid tightness.

[0005]

If the above-mentioned stopper bolt is not hardened, there is a possibility that the end face of the stopper bolt is deformed and destroyed at the time of abutting against the sector gear. Also, if the entire surface of the stopper bolt is quenched to prevent deformation and destruction of the tip end surface, the area of the abutting portion between the tooth surface of the sector gear and the end surface of the stopper is small, so that plastic deformation is small even at high surface pressure. Alternatively, there is a problem that cracks occur on both surfaces.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and provides an integral type power steering apparatus having a stopper which is free from deformation and destruction.

[0007]

An integral type power steering apparatus according to the present invention includes a piston slidably fitted in a cylinder, a rack formed on a side surface of the piston, and meshing with the rack. A sector gear and a stopper bolt screwed into the gear housing and abutting against the sector gear to regulate its rotation angle are provided.In particular, the tip surface of the stopper bolt abutting against the sector gear is bulged, and The outer peripheral portion and the threaded portion screwed to the gear housing are hardened by quenching.

[0008]

In the integral type power steering apparatus according to the present invention, when the sector gear is rotated and abutted against the stopper bolt, the bulge portion of the stopper bolt is recessed, the contact area increases, and the surface pressure decreases.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a longitudinal sectional view showing an integral type power steering device according to an embodiment of the present invention. A piston 6 is slidably fitted in a cylinder portion 4 of a gear housing 2. The inside of the cylinder 4 is divided into two pressure chambers 8 and 10 by 6. A rack 12 is formed on the side surface (the lower surface in FIG. 1) of the piston 6, and a sector gear 14 interlocked with a steering wheel (not shown) is meshed with the rack 12. It works. Gear housing 2
(Gear chamber) 15 in which the sector gear 14 is housed
Communicates with one pressure chamber 10 via the passage 2a.

A ball screw groove 18 is screwed into the hole 16 at the axial center of the piston 6, and a large number of balls 20 in the groove 18 are provided.
The worm shaft 22 is screwed through the shaft. A valve housing 24 is fixed to one end of the gear housing 2, and the worm shaft 22 is provided in the valve housing 24.
A stub shaft (input shaft) 26 is arranged so that the axis of the stub shaft coincides with that of the stub shaft. A cylindrical hole is formed in the worm shaft 22 on the stub shaft 26 side, and an end of the stub shaft 26 is fitted in the hole 22a. Are connected by a torsion bar 28 inserted into the torsion bar. The stub shaft 26 is linked to a steering handle (not shown).

In the valve housing 24, a valve rotor 30 that rotates integrally with a stub shaft 26, and a worm shaft 22
And a rotary type control valve 34 composed of a valve sleeve 32 formed therein.

The control valve 34 is connected to the supply passage 24a.
A passage 32b is connected to an oil pump (not shown) via an inlet port 24b, and to a tank via a recirculation passage and an outlet port (not shown). Pressure chamber 1 on the right
0. When the control valve 34 is switched by the operation of the steering handle, the pressure fluid discharged from the oil pump is supplied to one of the pressure chambers 8 and 10, and the other pressure chamber is communicated with the tank so that the two chambers communicate with each other. A pressure difference occurs between the piston 6 and the pressure difference.
To apply an assisting force in the steering direction.

The sector gear 1 is mounted on the wall of the gear housing 2 around the gear chamber 15 in which the sector gear 14 is housed.
A pair of stopper bolts 36 are provided to regulate the rotation angle of the shutter 4 in the left-right direction. These stopper bolts 36
Is screwed into a screw hole 2c formed in the gear housing 2, is fixed by a nut 38, and maintains the liquid tightness in the gear chamber 15 by an O-ring 40 fitted around the nut 38. The stopper bolt 36 is disposed so as to contact the tooth surface 14a of the sector gear 14 substantially at right angles, as shown on the left side of FIG.

The distal ends 36a of the stopper bolts 36 are spherically swelled, and a high frequency is applied from the outer peripheral portion of the distal end surface to a portion near the distal end of the screw portion screwed into the screw hole 2c of the gear housing 2. Hardening is performed by quenching or the like (indicated by reference numeral 36b in FIG. 2). The central portion of the distal end surface 36a of the stopper bolt 36 is less affected by hardening due to induction hardening and is softer than the outer hardened portion 36b.
The sector gear 14 is carburized and quenched.

In the integral type power steering apparatus according to the above configuration, when the control valve is switched by operating the steering handle, the pressure oil from the pump is supplied to one of the pressure chambers 8 or 10 and the other pressure chamber is supplied to the other pressure chamber. The hydraulic oil in the chamber 10 or 8 is returned to the tank, and the pressure difference between the two chambers 8 and 10 moves the piston 6 to rotate the sector gear 14.

When the sector gear 14 rotates and reaches an extreme position for meshing with the rack 12 formed on the piston 6 and the tooth surface 14a of the sector gear 14 abuts against the distal end surface 36a of the stopper bolt 36, a load is applied. 3
The bulged central portion of 6 is recessed (see the stopper bolt 36 on the right side in FIG. 2), so that the contact area between the two 14 and 36 increases and the surface pressure decreases. By reducing the surface pressure in this way, it is possible to prevent abnormal surface pressure concentration only at the abutting portion of the tooth surface 14a of the sector gear 14 and the end surface 36a of the stopper bolt 36, and to prevent the occurrence of damage such as cracks. Can be.

The recess of the stopper bolt 36 is
Since this occurs due to one or two loading operations, a dent is formed before the adjustment at the time of shipment of the vehicle, so that the rotation angle of the sector gear 14 does not change with time thereafter.

[0018]

As described above, according to the present invention, abnormal contact pressure does not occur when the sector gear and the stopper bolt abut against each other, and cracks and the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an integral type power steering device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 2 Gear Housing 4 Cylinder 6 Piston 12 Rack 14 Sector Gear 36 Stopper Bolt 36a Tip Face of Stopper Bolt

Claims (1)

(57) [Scope of request for utility model registration] 1. A piston slidably fitted in a cylinder, a rack formed on a side surface of the piston, a sector gear meshing with the rack, and a threaded engagement with a gear housing. In an integral type power steering device having a stopper bolt for regulating a rotation angle, a tip end surface of the stopper bolt abutting against a sector gear is swelled, and an outer peripheral portion of the tip end surface is screwed to a gear housing. An integral type power steering device characterized by hardening a screw portion by hardening.