JP2000127998A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate installing work and complicated laying work of external piping at vehicle mounting time by integrally forming an oil passage for communicating a control valve to a power cylinder in a cylinder tube. SOLUTION: A control valve C for alternatively supplying pressure oil from a hydraulic pump P to one of left/right oil chambers 19, 20 of a power cylinder 8 mutually partitioned by a piston 18 on the basis of relative angular displacement between input/output shafts and returning oil from the other oil chamber to an oil tank T, is built in an upper housing 11. An oil passage 21 communicating with a pair of oil chambers 19, 20 of the power cylinder 8 from the control valve C is integrally formed in a cylinder tube 3 formed of an extruded material of aluminum. Thus, when mounting a power steering device 1 on a vehicle, installing work and laying work of external piping are obviated. The power steering device can be laid out in the vehicle without considering interference between the external piping and the other part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for supplying and discharging oil to and from a power cylinder via a control valve.

[0002]

2. Description of the Related Art Conventionally, in some rack-and-pinion type steering devices, a steering assist force is obtained by hydraulic pressure. In this type of power steering device, a rack shaft is disposed in a gear housing and a cylinder tube connected to each other so as to be able to reciprocate in the axial direction thereof. The rack shaft meshes with a pinion in the gear housing, and both ends of the rack shaft protrude outside the gear housing and the cylinder tube, and are connected to steering wheels via tie rods.

The above-mentioned cylinder tube forms a power cylinder by surrounding a rod formed on a part of a rack shaft. A piston that moves integrally with the rod in the axial direction is accommodated in the power cylinder, and a pair of oil chambers is defined on both sides of the piston. In addition, this type of power steering device includes a control valve. The control valve selectively supplies pressure oil from a hydraulic pressure source to one oil chamber of a power cylinder, and supplies the pressure oil from the other oil chamber. To return the oil to the oil tank.

Conventionally, a pair of external pipes (feed tubes) are provided to connect between corresponding ports to communicate a control valve with a pair of oil chambers of a power cylinder. However, when the power steering device is mounted on a vehicle, the feed tubes must be laid out so that the feed tubes do not interfere with other components mounted on the vehicle, which complicates the layout. It is very difficult to assemble the feed tube in such a complicated layout while routing it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a power steering apparatus which can be easily assembled to a vehicle and has a high degree of freedom in layout.

[0006]

Means for Solving the Problems As means for solving the problems to achieve the above object, the aspect of the invention described in claim 1 is as follows.
A power cylinder formed so as to surround a rod around a rod by a cylinder tube, and a pair of oil chambers are defined with a piston interposed therebetween; and a control valve for controlling supply and discharge of pressurized oil to and from the oil chamber of the power cylinder. An oil passage communicating the valve with the oil chamber of the power cylinder is formed integrally with the cylinder tube.

In this embodiment, since the oil passage is built in the cylinder tube, it is not necessary to mount an external pipe (feed tube) and perform a complicated routing work as in the related art when the vehicle is mounted on a vehicle. There is no problem such as interference between the feed tube and other parts as in the related art, and the degree of freedom in layout when mounted on a vehicle is increased. It is preferable that a pair of oil passages respectively communicating with the pair of oil chambers of the control valve and the power cylinder be formed integrally with the cylinder tube.
Only one oil passage may be formed integrally with the cylinder tube.

According to a second aspect of the present invention, in the first aspect, the cylinder tube is made of an extruded aluminum material, and the oil passage is formed at the time of extrusion. In this aspect, by using an extruded aluminum material as the cylinder tube, the oil passage can be easily formed integrally with the cylinder tube.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partially broken side view of a main part of a power steering device according to an embodiment of the present invention. Referring to FIG. 1, a power steering device 1 includes a rack and pinion mechanism with hydraulic power assist including a rack shaft 2 and a pinion (not shown).

The rack shaft 2 is slidably supported in the axial direction within a cylinder tube 3 extending in the left-right direction of the vehicle body and a gear housing 4 connected to one end of the cylinder tube 3. Although not shown, both ends of the rack shaft 2 are connected via ball joints to tie rods respectively connected to the front wheels. A rod 5 is formed on a part of the rack shaft 2, and a gap between the rod 5 and a cylinder tube 3 surrounding the rod 5 is sealed by a pair of oil seals 6 and 7, thereby providing a steering assist force. A power cylinder 8 for generation is configured.

The gear housing 4 includes the cylinder tube 3
A lower housing 10 having a support cylinder 9 press-fitted to one end of the lower housing 10 and an upper housing 11 extending upward obliquely to the support cylinder 9 of the lower housing 10 are provided. The support cylinder portion 9 has a reduced diameter portion 9a on the distal end side press-fitted into the cylinder tube 3, and as shown in FIG. 3, which is an enlarged view of a main part of FIG. An annular step portion 24 with which one end of the cylinder tube 3 is abutted is formed therebetween.

The oil seal 6 at one end (the gear housing 4 side) of the cylinder tube 3 is in contact with the end surface of the support cylinder 9. An oil seal 7 at the other end of the cylinder tube 3 is fitted in the cylinder tube 3 and supports a rack bush 12 slidably supporting the rack shaft 2.
Is held by Reference numeral 13 denotes a rack stopper fixed to an end of the cylinder tube 3 for restricting a stroke amount of the rack shaft 2. The rack stopper 13 is
Sleeve 14 fitted in cylinder tube 3
And a flange 16 for pressing and holding the packing 15 between the end face of the cylinder tube 3.

Reference numeral 17 denotes an input shaft of the power steering device 1 connected to a steering wheel (not shown).
Has an upper end projecting from the upper housing 11. Although not shown, an output shaft that forms a pinion and a torsion bar that connects the input shaft 17 and the output shaft so as to be capable of relative angular displacement are accommodated in the upper housing 11.

Further, in the upper housing 11, pressure oil from the hydraulic pump P is supplied to the left and right oil chambers 19, 20 of the power cylinder 8 separated from each other by the piston 18 based on the relative angular displacement between the input and output shafts. And a control valve C for returning the oil from the other oil chamber to the oil tank T. The piston 18 is fixed to the rod 5 so as to be integrally movable in the axial direction. An O-ring 30 with a backup ring is housed in the outer peripheral groove of the piston 18, and oil flow between the oil chambers 19 and 20 is regulated.

The cylinder tube 3 is formed of an extruded aluminum material as shown in FIG. 2, and oil passages 21 and 22 communicating from the control valve C to a pair of oil chambers 19 and 20 of the power cylinder 8 are integrated at the time of extrusion. It consists of what was formed in. 2 and 3, the cylinder tube 3 has a thick portion 23 extending in the axial direction.
The pair of oil passages 21 and 22 pass through the thick portion 23 in the axial direction so as to extend in parallel with the cylinder hole 3a.

Referring to FIG. 4, which is a cross-sectional view taken along the line IV-IV in FIG. 3, the cylinder tube 3 is connected to the oil chamber 19 of the power cylinder 8 so as to communicate with the oil passage 21. 3, a communication passage 27 extending in the radial direction is formed. Referring to FIG. 5 which is a cross-sectional view taken along the line VV in FIG.
A communication passage 28 extending in the radial direction of the cylinder tube 3 is formed so as to communicate the oil chamber 20 with the oil passage 22.

As a method of forming these communication passages 27 and 28, there is a method of punching a punch hole from the inside of the cylinder tube 3. As shown in FIG. 6, the oil passage 21 (or 2) is provided from outside the thick portion 23 of the cylinder tube 3.
After the through hole 31 is formed in such a manner as to penetrate through 2) and reach the corresponding oil chamber 19 (or 20), a plug 32 is inserted into the opening of the through hole 31 opened in the thick portion 23. May be.

Referring again to FIG. 3, one end of the oil passage 21 is sealed by the packing 16, and the other end of the oil passage 21 communicates with an oil passage 29 formed in the lower housing 10. A step portion 24 is formed at the base end of the reduced diameter portion 9a of the support cylinder portion 9,
In a state where, for example, an O-ring 26 is accommodated in an annular concave portion 25 formed in the step portion 24, the step portion 24 is
Butted against the end face. Thereby, the fluid tightness of the communicating part between the oil passage 21 and the oil passage 29 on the lower housing 10 side is ensured. The oil passage 29 reaches a valve housing (not shown) of the control valve C.
The oil passage 21 is communicated with the control valve C via the.

Although not shown, the oil passage 22 and the oil passage formed in the lower housing 10 for connecting the oil passage 22 to the control valve C are connected to each other in the same configuration as that of the oil passage 21. . In the present embodiment, a pair of oil chambers 19 of the control valve C and the power cylinder 8 are provided.
Since the oil passages 21 and 22 for communicating with the power steering device 20 are formed integrally with the cylinder tube 3, when the power steering device 1 is mounted on a vehicle, a conventional external pipe assembling operation or complicated operation is required. Eliminating the work is unnecessary. Without considering the conventional interference between the feed tube and other parts,
Since the power steering device 1 can be laid out in the vehicle, the degree of freedom in layout is increased.

In particular, by using an extruded material of aluminum as the cylinder tube 3, the oil passages 21 and 22 can be easily formed integrally when the cylinder tube 3 is formed by extrusion, and post-processing after drilling becomes unnecessary. Note that the present invention is not limited to the above-described embodiment. For example, only one of the pair of oil passages 19 and 20 is formed integrally with the cylinder tube 3, and the other oil passage is configured by a conventional feed tube. Also in this case, since one feed tube can be omitted, assembling workability is improved and layout flexibility is increased. In addition, various changes can be made within the scope of the present invention.

[0021]

According to the first aspect of the present invention, since the oil passage communicating the control valve and the power cylinder is formed integrally with the cylinder tube, the conventional external pipe assembling work and complicated work can be performed when mounted on a vehicle. Eliminating the work is unnecessary. In addition, the layout can be performed without considering the interference with other parts and the like, and the flexibility of the layout is increased.

According to the second aspect of the present invention, by using an extruded aluminum material as the cylinder tube, the oil passage can be easily integrally formed when the cylinder tube is extruded, and no post-processing is required.

[Brief description of the drawings]

FIG. 1 is a partially broken side view of a power steering device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cylinder tube.

FIG. 3 is an enlarged view of a main part of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a sectional view taken along the line VV of FIG. 3;

FIG. 6 is a sectional view of a main part of a cylinder tube showing an example of a method of forming a communication passage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power steering device 2 Rack shaft 3 Cylinder tube 4 Gear housing 5 Rod 8 Power cylinder 9 Support cylinder 10 Lower housing 15 Packing 18 Piston 19,20 Oil chamber 21,22 Oil passage 27,28 Communication passage 29 Oil passage C control valve

Claims (2)

[Claims] 1. A power cylinder formed around a rod by a cylinder tube and defining a pair of oil chambers with a piston interposed therebetween, and a control valve for supplying and discharging pressurized oil to and from the oil chamber of the power cylinder. A power steering device comprising: an oil passage that communicates the control valve with an oil chamber of a power cylinder, the oil passage being formed integrally with a cylinder tube. 2. The power steering apparatus according to claim 1, wherein said cylinder tube is made of an extruded aluminum material, and said oil passage is formed at the time of extrusion.