JP2583958Y2 - 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 a hydraulic power steering device that generates a steering assist force by a hydraulic actuator disposed in a steering mechanism.

[0002]

2. Description of the Related Art In recent years, a hydraulic power steering device that assists a force required for steering operation for steering by hydraulic pressure has been developed to realize a comfortable steering feeling in recent years as well as large vehicles such as trucks and buses. It is widely used in ordinary passenger cars. This power steering device arranges a hydraulic actuator such as a power cylinder that generates a steering assist force in a steering mechanism,
A hydraulic control valve for controlling the operating oil pressure to the hydraulic actuator in accordance with the steering operation is interposed between this and a hydraulic pump as a hydraulic pressure generating source.

FIG . 3 shows a gear housing 11 for meshing and holding a pinion of a pinion shaft connected to a steering wheel and a rack shaft in a conventional power steering apparatus, and a cylinder tube 10 constituting a hydraulic cylinder 4 for generating a steering assist force. FIG. 2 is a front view showing a partially cut-out portion of a connection with a rack shaft, in which 1 indicates a rack shaft. The rack shaft 1 is disposed in a mutually connected gear housing 11 and a cylinder tube 10 so as to be able to reciprocate in the direction of the axis of the rack. In the gear housing 11, the rack is engaged with a pinion of a pinion shaft. Both ends protrude outside from the gear housing 11 and the cylinder tube 10 and are connected to the steered wheels via tie rods (not shown).

The pinion shaft has a torsion bar (not shown),
The steering shaft is connected to the steering wheel via the input shaft, and the steering of the rack shaft is reciprocated left and right by operating the steering wheel. The gear housing 11 and the cylinder tube 10 are supported by a support cylinder portion extending from the gear housing 11.
One end of the cylinder tube 10 is press-fitted to the outside of the cylinder tube 11a and integrally connected to each other by a set screw 11b. A sliding bearing 8 for the rack shaft 1 is fitted inside the end of the support cylinder 11a, and a backup washer 6a and an oil seal 7a are fitted inside the cylinder tube 10 in close proximity to the bearing. One oil chamber A of the cylinder 4 is provided with a hydraulic pressure for generating a steering assist force constituted by the tube 10.

[0005]

In such a conventional apparatus, when one end of the cylinder tube 10 is press-fitted to the support cylinder 11a of the gear housing 11, the slide first slides into the support cylinder 11a. After the bearing 8 is press-fitted, one end of the cylinder tube 10 is press-fitted to the support cylinder portion 11a, and the backup washer 6a and the oil seal 7a are inserted and positioned from the other end of the cylinder tube 10, and assembled. ,
Cylinder tube 10 slides through support cylinder 11a
Therefore, the inner diameter of the slide bearing 8 is changed, the friction between the rack shaft 1 and the slide bearing 8 is increased, and the operation of the rack shaft 1 becomes heavy.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent a change in the inner diameter of a slide bearing when a cylinder tube is press-fitted and externally fitted to a support cylindrical portion of a housing. With oil seal
It is an object of the present invention to provide a power steering device capable of easily performing a replacement operation of a vehicle.

[0007]

SUMMARY OF THE INVENTION A power steering apparatus according to the present invention meshes and holds a pinion of a pinion shaft connected to a steering wheel and a rack of a rack shaft connected to a steering wheel. A housing provided with a support cylinder portion press-fitted with a slide bearing for supporting the same, and a hydraulic cylinder for generating a steering assist force, wherein a cylinder tube is disposed around a piston provided on the rack shaft, in the power steering apparatus ends were press fitted outside of the support tube portion end of the cylinder tube, the end portion of the support cylinder portion of the housing, through the backup washer, provided unstoppable oil seal fitted in the cylinder , co if at least the outer diameter of said supporting tube portion of the portion corresponding to the sliding bearing press-fit portion, to which is smaller than said end portion inner diameter of the press-fitting to be the cylinder tube The sliding bearing, the support tube portion
It is characterized by being press-fitted and positioned away from the terminal at the end .

[0008]

Is a to the present invention, the end portion outer diameter of the support tube of the corresponding parts as to be press-fitted position of the sliding bearing,
Since the inner diameter of the end of the cylinder tube to be press- fitted is smaller than this, even if the cylinder tube is press-fitted and externally fitted, the support cylinder and cylinder tube will not be press-fitted at the part where the sliding bearing is located. And does not affect the inner diameter of the sliding bearing. In addition, the slide bearing is provided at the end of the support cylinder.
Because of being pressed into a position away from the terminal, it is possible to remove the backup washer and oil seal independently of the sliding bearing by using a jig.

The case where the present invention is applied to a hydraulic power steering apparatus having a rack and pinion structure will be specifically described with reference to the drawings. FIG. 1 is a partially cutaway front view showing a main part of the power steering device according to the present invention. In the figure, reference numeral 1 denotes a rack shaft, which is supported inside a cylindrical cylinder tube 10 fixed to the front of the vehicle body and a gear housing 11 connected to one end thereof so as to be slidable in the axial direction. Both end portions of the tire 1 are connected to tie rods 12 and 12 respectively connected to left and right front wheels (not shown) via separate ball joints 13 and 13, respectively.

The gear housing 11 is connected to one end of the cylinder tube 10 in an oblique manner, and a hydraulic control valve 14 is provided on the upper side. Hydraulic control valve 14,
In the gear housing 11, an input shaft 2 is supported on the upper side, and a pinion shaft (not shown) is supported on the lower side in the middle thereof so as to be rotatable coaxially. The input shaft 2 and the pinion shaft are connected via a torsion bar (not shown), and the pinion of the pinion shaft meshes with the rack of the rack shaft 1 in the gear housing 11.

The upper end of the input shaft 2 projecting out of the gear housing 11 is connected to a steering wheel (steering wheel) 3. When the steering wheel 3 is rotated, the rotation is performed by the input shaft 2 and the torsion bar. And the rack shaft 1 meshing with the pinion shaft is slid in the axial direction and transmitted to the left and right front wheels via the ball joints 13 and 13 and the tie rods 12 and 12 for steering. .

A hydraulic cylinder 4 for assisting the steering is provided with a circular piston 5 fixedly mounted in the middle of the rack shaft 1, and a cylinder tube 10 is fitted around the outer periphery of the piston 5 coaxially therewith. Backup washers 6a and 6b and oil seal 7 at both ends of 10 respectively
The gap between the rack shaft 1 and the cylinder tube 10 is sealed by a and 7b, and oil chambers A and B are formed on both sides of the piston 5, respectively. The rack shaft 1 is pressed by the pressure difference via the piston 5 to assist the sliding of the rack shaft 1, that is, the steering operation.

An inlet / outlet for hydraulic oil is opened in a peripheral wall of the cylinder tube 10 facing the oil chambers A and B, and these inlets / outlets are fixed to feed tubes 9 and 9 respectively.
And a hydraulic pump and an oil tank (not shown) are connected thereto. When pressure oil is supplied into the oil chamber A by the hydraulic control valve 14, the hydraulic oil is directed to the right side and the oil chamber B When supplied to the inside, each steering assist force for the left side is generated.

FIG. 2 is a partially enlarged side view showing a part of the connection between the gear housing 11 and the cylinder tube 10 partially broken away. One end of 10 is press-fitted and externally fitted to a position where its distal end surface abuts a step 11c provided at the base of the support cylinder 11a, and is integrally fixed by a set screw 11b. The inside of the end of the support cylinder 11a and the inner side away from the terminal by a predetermined distance L, the rack shaft 1
A slide bearing 8 is press-fitted, and a backup washer 6a and an oil seal 7a are interposed in the cylinder tube 10 in contact with the end of the support cylinder 11a.

In the device of the present invention, the support cylinder 11
The outer diameter of a is slightly reduced from the terminal side to a portion corresponding to the position where the slide bearing 8 is located, or over a wider area than this, and in this reduced area, the cylinder tube 10 is connected to the support cylinder 11a. A gap d of about 0.05 to 0.08 mm is formed between each other even in the state where the press fitting is performed.

[0016] In such a device of the present invention,
The outer peripheral surface of the end portion of the support cylinder portion 11a in the gear housing 11 is moved in the axial direction in advance at least from the end thereof to the sliding bearing 8.
The outer diameter of the cylinder tube 10 is set slightly smaller than the inner diameter of one end of the cylinder tube 10 fitted over the range including the portion corresponding to the portion where the is located. After press-fitting the slide bearing 8 inside the support cylinder 11a, one end of the cylinder tube 10 is press-fitted to the support cylinder 11a. After press-fitting the cylinder tube 10, press the cylinder tube
From the end opposite to 10, the backup washer 6a and the oil seal 7a are placed in this order by the backup washer 6a.
Insert until it hits the end face of 11a. Support tube 11a
Since the tip portion outside diameter are slightly smaller than the inner diameter of the cylinder tube 10, the cylinder tube 10 supporting cylinder unit 11
It functions as a guide when press-fitting into a, and press-fitting work of the cylinder tube 10 becomes easy.

Further, even when the cylinder tube 10 is externally press-fitted, there is a gap between the cylinder tube and the portion where the slide bearing 8 is located and the outer peripheral surface of the corresponding support cylinder portion 11a. Since this is not the case, the inner diameter of the sliding bearing 8 is not damaged .

Further, in the conventional apparatus shown in FIG. 3, the length of the support portion for supporting the rack shaft 1 is increased to increase the deflection and prevent the oil seal from being damaged .
The sliding bearings 8, backup washer 6a, oil seal
Since 7a is interposed close to the connecting portion between the support cylinder portion 11a and the cylinder tube 10 , for example , if the oil seal 7a needs to be replaced due to maintenance and inspection,
The oil seal 7a cannot be removed simply by removing the rack shaft 1, and the cylinder tube 10 is further connected to the support cylinder 11
a, the replacement of the oil seal 7a is extremely troublesome.

[0019]

On the other hand, in the embodiment of the present invention, when replacing the oil seal 7a, the rod-shaped jig M is inserted from the gear housing 11 while the rack shaft 1 is removed, and the tip of the rod jig is connected to the support cylinder 11a. The backup washer 6a and the oil seal 7a can be pushed out to the inner diameter expanding portion 10a of the cylinder tube 10 by hitting and pressing the backup washer 6a set to an inner diameter smaller than the inner diameter, and the replacement work can be performed. This can be performed without removing the cylinder tube 10 from the gear housing 11, and the replacement operation is facilitated .

[0021]

As described above, in the device according to the present invention, the outer diameter of the portion corresponding to the sliding bearing press-fitted into the support cylinder portion, which is extended from the housing, is press-fitted here. Since the inner diameter of the cylinder tube is smaller than the inner diameter of the cylinder tube to be inserted, even if the end of the cylinder tube is press-fitted into the end of the support cylindrical portion, this portion does not become a press-fit state, thereby affecting the inner diameter dimension of the slide bearing. Nothing. In addition, since the sliding bearing is press-fitted to the inner deep portion of the support cylindrical portion away from the end of the end portion, when replacing the oil seal,
The oil seal and the backup washer can be removed independently of the slide bearing.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a main part of a power steering device according to the present invention.

FIG. 2 shows a connecting portion between a gear housing and a cylinder tube.
It is an expanded sectional view of a minute.

FIG. 3 shows a gear housing and a cylinder in a conventional device .
It is an expanded sectional view of the connection part with a tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rack shaft 2 Input shaft 3 Steering wheel 4 Hydraulic cylinder 5 Piston 6a, 6b Backup washer 7a, 7b Oil seal 8 Slide bearing 10 Cylinder tube 11 Gear housing 11a Support cylinder 11b Set screw 12 Tie rod 13 Ball joint d Clearance

Claims (1)

(57) [Scope of request for utility model registration] 1. A supporting cylinder portion which meshes and holds a pinion of a pinion shaft connected to a steering wheel and a rack of a rack shaft connected to a steering wheel, and press-fits a slide bearing for supporting the rack shaft inside. And a hydraulic cylinder for generating a steering assist force in which a cylinder tube is disposed around a piston provided on the rack shaft, and an end of the cylinder tube is press-fitted into an end of the support cylinder portion. In the power steering device fitted outside, an oil seal fitted in the cylinder is provided at the end of the support cylindrical portion of the housing via a backup washer, and at least a portion corresponding to a portion into which the slide bearing is press-fitted. the outer diameter of the support tube portion, as well as smaller than the end portion inner diameter of the press-fitting to be the cylinder tube thereto, the sliding bearing, the end of said end portion of the supporting cylinder unit It pressed away from the power steering apparatus characterized by being positioned.