JPS6137572Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device using a torsion bar that prevents accidents due to steering failure even if the torsion bar is damaged.

In a power steering device using a general rotary valve, if a torsion bar connecting a stub shaft and a wormshaft is damaged, the stub shaft may spin idling, making steering operation impossible.

FIG. 1 is a longitudinal sectional view of a conventional rotary valve type power steering device. In the figure, a cylindrical wormshaft 3 is concentrically provided at the tip of a stubshaft 2 that is concentrically fixed to a yoke 1 that is rotated by a handle operation.
A torsion bar 4 having one end fixed to the stub shaft 2 and the other end fixed to the tip of the wormshaft 3 is disposed on the inner circumference of the worm shaft 3. stub shaft 2
A cylindrical rotor 5 is provided on the outer periphery of the stub shaft 2, and the rotor 5 is connected to the stub shaft 2 so as to rotate together with the stub shaft 2 by being engaged with a pin 6 planted on the stub shaft 2. A cylindrical sleeve 7 is fitted around the outer periphery of the rotor 5 so as to be slidable in the circumferential direction.
is formed integrally with. The rotor 5 and the sleeve constitute a rotary valve, and by rotationally displacing each other in the circumferential direction, the flow path is switched and a well-known valve action is performed. This sleeve 7 is housed in a valve body 8 and is supported by a bearing portion formed by a steel ball 9 on the valve body 8 . Further, an end cover 11 provided with a ball bearing 10 is screwed into the opening of the valve body 8, and the stub shaft 2
is supported by this ball bearing 10 via the yoke 1.

On the other hand, there is a ball 1 on the outer periphery of the wormshaft 3.
A piston 15 is screwed together via a ball screw mechanism using 4. This piston 15 is housed within a cylinder body 16 and is adapted to move in the axial direction when the worm shaft 3 rotates. Further, a rack tooth 17 is formed on a part of the outer circumference of the piston 15, and a sector shaft 18 connected to a pitman arm (not shown) is engaged with the rack tooth 17. When the piston 15 moves in the axial direction, a sector shaft 18 is engaged with the rack tooth 17. The shaft 18 is rotated to perform a steering operation. A left cylinder chamber 19 is formed in a space surrounded by the left side surface of the piston 15 and the cylinder body 16.
right side, cylinder body 16 and valve body 8
A right cylinder chamber 20 is formed in the space surrounded by.

In addition, the protrusion 2 formed on the stub shaft 2
2 acts so that it hits the wormshaft 3 and rotates integrally with the wormshaft 3 when the stubshaft 2 is rotationally displaced by a predetermined angle or more with respect to the wormshaft 3.

FIG. 2 is a cross-sectional view of FIG. 1. A recess 23 is formed in the wormshaft 3, and the stub shaft 2 and the wormshaft 3 are assembled so that the protrusion 22 fits into the recess 23. When neither the stub shaft 2 nor the worm shaft 3 is subjected to rotational force, the torsion bar 4 positions the protrusion 22 in the center of the recess 23 . When the stub shaft 2 rotates by more than a predetermined angle with respect to the worm shaft 3, the protrusion 22 comes into contact with the inner surface of the recess 23, and the worm shaft 3 rotates together with the stub shaft 2 from then on.

In such a configuration, when the stub shaft 2 is rotated, for example, to the right by the yoke 1 by operating the handle, this rotation is transmitted to the wormshaft 3 via the torsion bar 4. When the wormshaft 3 rotates, the piston 15, which is screwed into the wormshaft 3, moves to the right in the figure. At this time, the rotor 5 rotates together with the stub shaft 2, and the flow path of the rotary valve is switched, so that the pressurized working fluid enters the left cylinder chamber 19, and at the same time, the working fluid in the right cylinder chamber 20 flows out. As a result, the piston 15 receives a large applied force in the right axial direction due to the pressure of the working fluid. In this way, since a large additional force is applied in the same direction on top of the manual force, steering operations can be performed with light input.

When the stub shaft 2 is rotated to the left, a similar operation is performed and the piston 15 moves to the left.At the same time, the flow path of the rotary valve is switched and the working fluid enters the right cylinder chamber 20, and at the same time, the piston 15 moves to the left.
The working fluid that is present will flow out. As a result, the piston 15 receives a large applied force in the left axial direction due to the pressure of the working fluid, and the steering operation is performed with a similarly light input.

In addition, if the power steering function does not work because the pressure of the working fluid is not applied to the piston 15 due to a malfunction, the stub shaft 2 and the worm shaft 3 rotate together as explained in FIG. Steering operation is performed by. That is, if there is no added force due to the pressure of the working fluid, the load on the wormshaft 3 for moving the piston 15 will be heavy, so even if the stub shaft 2 is rotated, the wormshaft 3 cannot be rotated only by the torsional force of the torsion bar 4. do not. If the stub shaft 2 is further rotated in this state, the protrusion 22 will come into contact with the inner surface of the recess 23, and from then on, the stub shaft 2 and wormshaft 3 will rotate together, allowing manual steering operation, although it will be heavier. .

However, in conventional power steering devices, strain tends to concentrate on the stepped base of the torsion bar 4 (indicated by A in Figure 1), but in the unlikely event that the torsion bar 4 is damaged at this part due to stress due to torsion. In this case, you will be unable to steer the vehicle at all. That is, although not shown, the yoke 1 is connected to a drive shaft of the handle via a universal joint, and this drive shaft usually has a predetermined amount of play in the axial direction. In addition, in order to facilitate assembly work, the stub shaft 2 and rotor 5 are
Since the stub shaft 2 and the rotor 5 are inserted straight into the wormshaft 3 and the sleeve 7, there is nothing other than the torsion bar 4 to prevent the stub shaft 2 and the rotor 5 from coming off. Therefore, if the torsion bar 4 is damaged and cut, the stub shaft 2 will fly out together with the yoke 1 (to the right in the figure) due to the pressure of the working fluid. When the stub shaft 2 moves outward by a predetermined distance or more, the protrusion 22 comes out of the recess 23. In this situation, stub shaft 2
Even if the wormshaft 3 rotates, it simply spins idly and the wormshaft 3 does not rotate at all, which makes steering operation impossible and is very dangerous.

This invention was devised to solve these conventional problems, and its purpose is to:
To provide a rotary valve type power steering device which allows manual steering operation even if an accident such as damage to a torsion bar occurs.

In order to achieve such an objective, the present invention has an inner diameter smaller than the outer diameter of the rotor, and is provided on the outer periphery of the stub shaft, so that the rotor has an inner diameter smaller than the outer diameter of the rotor, and a ball is provided on the fixed part side of the stub shaft. The part corresponding to the inner ring on the supported rotating side is used as a stopper to prevent the rotor from coming off.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 3 is a longitudinal sectional view of a main part of an embodiment of the rotary valve type power steering device according to the present invention. In the figure, parts that are the same as those in FIG. 1 are given the same numbers. Now,
According to the present invention, the sleeve 7 is a rotating part fitted to the rotor 5 so as to be able to be angularly displaced relative to the rotor 5.
A groove 25 is formed in the circumferential direction on the inner circumferential surface of the inner ring of the bearing part by the balls 9 that support the sleeve 7 on the valve body 8 side as a fixed part at the outer end of the sleeve 7. A snap spring 26 is fitted. For assembly, after inserting the rotor 5 into the inner periphery of the sleeve 7, fit the snap spring 26 into the groove 25, then screw the end cover 11 with the ball bearing 10 attached into the opening of the valve body, and then attach the yoke 1 to the stub. It is inserted between the shaft 2 and the ball bearing 10 and fixed to the stub shaft 2 in the same manner as in the prior art. The snap spring 26 is disposed to face the side end surface of the rotor 5, and the inner diameter of the snap spring 26 is set smaller than the outer diameter of the rotor 5. Therefore, even if the stub shaft 2 is Even if the rotor 5 is pushed by the stub shaft 2, it moves together with the stub shaft 2 due to the engagement of the pin 6.
The side end surface of the stub shaft 2 touches the snap spring 26, and the stub shaft 2 moves only a short distance. Therefore, the protrusion 22 does not come out of the recess 23, and since the snap ring 26 that the side end surface of the rotor 5 contacts is provided on the sleeve 7 side, which is the rotating part, no problem will occur during rotation. Manual steering operation is now possible. According to this embodiment, it can be applied to a conventional structure by simply providing a groove 25 and adding a snap spring 26, and the movement of the stub shaft 2 can be prevented with almost no increase in cost.

FIG. 4 is a longitudinal cross-sectional view of a main part of another embodiment. In the figure, the same parts as in FIGS. 1 and 3 are given the same numbers. The outer diameter of the portion of the yoke 1a fitted into the outer periphery of the stub shaft 2 is set smaller than the outer diameter of the rotor 5. Therefore, the ball bearing 10a that supports the yoke 1a, particularly its inner ring portion, has an inner diameter smaller than the outer diameter of the rotor 5, and is held by the end cover 11 and placed in a position facing the side end surface of the rotor 5. Ru.
As a result, the ball bearing 10a which is the rotating part
The side end surface of the inner ring portion of is used as a stopper, and even if the stub shaft 2 tries to move outward, the side end surface of the rotor 5 comes into contact with the ball bearing 10a and the movement is blocked, and the protrusion 22 stops in the recess 23.
There's no getting out of it. Since this embodiment has no additional parts and labor, movement of the stub shaft 2 can be prevented without any increase in cost.

As described above, according to the rotary valve type power steering device according to the present invention, even if an accident occurs in which the torsion bar is damaged, the stub shaft is engaged via the rotor due to the action of the stopper provided on the rotating part side. The problem of getting out after being stopped is eliminated, and problems such as poor rotation do not occur, and the steering operation can be performed manually, which has the effect of improving safety.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional rotary valve type power steering device, FIG. 2 is a cross-sectional view taken from FIG. 1, and FIG. 3 is an embodiment of a rotary valve type power steering device according to the present invention. FIG. 4 is a vertical cross-sectional view of a main part of another embodiment. 1...Yoke, 2...Stubshaft, 3...
Wormshaft, 4...Torsion bar, 5...
...rotor, 7 ... sleeve, 10 ... ball bearing, 11 ... end cover, 15 ... piston, 18 ... sector shaft, 22 ... protrusion,
23... recess, 25... groove, 26... snap spring.

Claims (1)

[Claims for Utility Model Registration] (1) A stub shaft that rotates when a handle is operated, a worm shaft that is provided concentrically with the stub shaft, a torsion bar that connects the worm shaft and the stub shaft, and the worm shaft. a piston screwed onto the outer periphery of the stub shaft; a sector shaft that rotates as the piston moves in the axial direction; a rotor provided on the outer periphery of the stub shaft so as to rotate together with the stub shaft; a sleeve that is slidably fitted around the outer periphery in the circumferential direction and is provided to rotate integrally with the wormshaft; 1. A power steering device using a torsion bar, characterized in that a portion corresponding to an inner ring supported on a fixed portion side via a ball serves as a stopper for preventing the rotor from coming off. (2) Utility model registration claim 1, characterized in that a snap spring loaded on the inner peripheral surface of the inner ring portion, which is a bearing for supporting a sleeve, is used as a portion corresponding to the inner ring that serves as a stopper to prevent the rotor from coming off. A power steering device using the torsion bar described in 2. (3) The torsion bar according to claim 1 of the utility model registration claim is used, characterized in that the side end surface of the inner ring of a stub shaft support bearing is used as a portion corresponding to the inner ring that serves as a stopper for preventing the rotor from coming off. Power steering device.