JPS6158345B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device, and more particularly to a power steering device that is miniaturized by reducing the dimension in the extending direction of the steering shaft.

As shown in Fig. 1, in a conventional power steering device, when road resistance is small, the rotation of a steering shaft 1 rotates a pinion 2, and a shaft 4 forming a rack 3 that meshes with the pinion 2 is moved in its axial direction. Steering the wheels. Further, when the road resistance is large, a valve mechanism 5 which is switched and operated depending on the relative angle difference between the steering shaft 1 and the pinion 2 is used to control the shaft 4, the cylinder 6 surrounding it, and the shaft 4. The hydraulic chambers 7 and 8 formed by the piston 4a are communicated with a hydraulic source or a drain, and the difference in hydraulic pressure assists the shaft 4 in a corresponding direction to move the shaft and steer the wheels. It is.

As the valve mechanism 5, one shown in FIG. 2 has been generally used. That is, in FIG. 2, 9 is a stub shaft consisting of a hollow shaft connected to the steering shaft 1;
10 is a pinion control installed inside the housing 11 so as to be able to rotate around the axis;
A pinion 2 is integrally formed at one end of this pinion control 10. Reference numeral 12 denotes a torsion bar, and both ends of the torsion bar 12 are supported by pins 13 and 14 on the stub shaft 9 and pinion control 10, respectively. 1
5 and 16 are the flange 9 of the stub shaft 9 when torsion occurs in the torsion bar 12, in other words, when a relative angle difference in the axial direction occurs between the stub shaft 9 and the pinion control 10.
This is a spool valve that is moved in a direction perpendicular to the axial direction of the stub shaft 9 by pins 17 and 18 implanted in a. This spool valve 15, 16
The hydraulic pressure chambers 7 and 8 are configured to switch an oil passage communicating with a hydraulic pressure source and a drain into communication with the hydraulic chambers 7 and 8. In addition, 19 is a ball bearing, 20, 21 is a needle bearing for supporting the stub shaft 9 concentrically to the pinion control 10, 23 is a thrust bearing, and 24a to 24g are seal rings.

The conventional valve mechanism 5 configured in this manner includes a pinion control 10, a spool valve 15,
16, the steering shaft 1
The disadvantage was that the dimension in the extending direction was relatively long.

In view of the above-mentioned drawbacks of the conventional art, the present invention improves the extension of the steering shaft by arranging a valve on the outer periphery of the pinion control to switch the fluid path to the hydraulic means that operates the gear means for wheel steering. In addition to being able to shorten the dimensions in the installation direction,
The present invention provides a power steering device that converts rotational motion into axial motion with small motion resistance when obtaining axial motion for driving a valve.

Hereinafter, according to the embodiments shown in FIGS. 3 to 7,
The present invention will be explained in detail.

3 to 6, reference numeral 31 denotes a stub shaft as a hollow input shaft connected to a steering shaft 32;
A protruding portion 31a is formed on the outer periphery of substantially the center of 1. 33 is a housing, and a side plate 34 into which the stub shaft 31 is inserted is screwed into an opening of the housing 33 via a seal 35. 36 is the side plate 34 and the stub shaft 31
This is a sealing member that seals between the A worm shaft 37 serves as a rotatable output shaft that passes through the housing 33 and concentrically covers the end of the stub shaft 31. A needle bearing 38 is interposed between them. 39 is a torsion bar, and one end of this torsion bar 39 is connected to the stub shaft 31.
The other end is fixed to the worm shaft 37 by a pin 41. 42 is a needle bearing interposed between the bottom surface of the housing 33 and the stepped portion 43 of the worm shaft 37. Reference numeral 44 denotes a sleeve provided on the outer periphery of the worm shaft 37 in the housing 33 so as to rotate together with the stub shaft 31 and to be slidable in the axial direction. A hole 45 is formed that penetrates the shoulder portion 4 from inside to outside.
4a includes a protrusion 31a of the stub shaft 31.
A pin insertion hole 47 is formed into which a pin 46 fixedly attached is slidably inserted. Reference numeral 48 denotes a ball bearing having an inner race fitted onto the outer periphery of the sleeve 44 so as to close the hole 45, and a nut 50 screwed into the threaded portion 49 formed at the end of the sleeve 44 against the shoulder portion 44a. This is a ball bearing that is pressed and fixed by Reference numeral 51 denotes a ball, which is inserted across the hole 45 and a slot 52 formed in a spiral shape on the outer peripheral surface of the worm shaft 37 at a position corresponding to the hole 45 of the sleeve 44. The ball bearing 4
It is in contact with the inner periphery of the inner race No. 8. Reference numeral 53 denotes a cylinder housing that covers the feed screw portion 55 of the worm shaft 37, which is attached to the housing 33 via a seal member 54. 56
is a needle bearing attached to the back surface of the housing 33 by a nut 58 that engages with a threaded portion 57 formed on the worm shaft 37. Reference numeral 59 denotes a cylindrical piston that slides within the cylinder housing 53, and a sealing lid 61 is screwed and fixed to the end of the piston 59 via a seal member 60. A rack 62 is also formed on the lower surface of the piston 59. A sector gear 63 is supported by the cylinder housing 53 and meshes with the rack 62. 64 is the feed screw portion 55 of the worm shaft 37 and the piston 5
This is a ball interposed between 9 and 9. Reference numeral 65 denotes a spool valve storage chamber formed in the cylinder housing 53, and a slidable spool valve 66 is provided within this storage chamber 65. A pin 67 has one end fixed to the spool valve 66 by a screw 68, and the other end screwed to a nut 69 fixed to the outer race 48a of the ball bearing 48.

In a power steering system configured in this way, when the steering wheel (not shown) is operated,
Relative torsional displacement occurs between the stub shaft 31 and the worm shaft 37 depending on the driving state of the vehicle and the road surface condition. At this time, stub shaft 3
Sleeve 4 that engages with a pin 46 fixed on one side
4 attempts to rotate relative to the wormshaft 37. However, a spiral slot 52 is formed on the outer peripheral surface of the wormshaft 37, and the remaining half of the ball 51, which is disposed approximately half buried in the slot 52, is inserted into the hole 45 of the sleeve 44.
It is coming within. Therefore, the sleeve 44 moves along with the ball 51, and this ball 51 is inserted into the slot 52 of the wormshaft 37.
Since the sleeve 44 is guided by the worm shaft 37, the sleeve 44 moves in the axial direction while rotating relative to the wormshaft 37. At this time, the ball 51 rolls against the inner peripheral surfaces of the slot 52 and the hole 45, so that the movement resistance is very small. Further, the ball bearing 48 is arranged so as to close the opening on the outer peripheral side of the hole 45 of the sleeve 44.
Since the inner race is fitted, movement of the ball 51 in the radial direction, which is pressed outward by the slot 52, is restricted.
Furthermore, since the pin 67 is screwed into a nut 69 fixed to the outer race 48a of the ball bearing 48, it moves only in the axial direction as the sleeve 44 moves. This allows pin 67
A valve 66, which engages one end of the valve 66, is driven axially by a pin 67. Thus, as the steering wheel is operated, the valve 66 reciprocates in the axial direction to control the amount of restriction to the passages 78, 84 and the pressure introduced into the left and right working chambers 79, 85. Therefore, the piston 59 is assisted depending on the steering direction.

Note that the worm shaft 37 has a notch 37a.
However, protrusions 31a are formed on the stub shaft 31, and the gaps between them are normally equal on the left and right sides. For example, if the hydraulic force cannot be obtained due to a pump failure, etc., this will engage directly.
It has come to function as so-called manual steering.

Further, in the above embodiment, the spool valve 66 is actuated by the pin 67 fixed to the outer race 48a of the ball bearing 48, but the spool valve 66 is not limited to this, and the spool valve 66 is actuated directly by the outer race 48a of the ball bearing 48. 66 may be activated. Further, although the spool valve 66 is used as the hydraulic means 74 in the description, the present invention is not limited to this, and similar effects can be obtained by using a rotary valve 66A as shown in FIG.

As is clear from the above description, the present invention has the following effects.

(1) Since the valve is provided on the outer periphery of the output shaft, there is no need for space to provide the valve on the output shaft, and the dimensions in the direction of extension of the steering shaft can be shortened to achieve downsizing.

(2) Since no valve is provided on the output shaft, it is easy to seal around the output shaft, making manufacturing easier and reducing costs.

(3) A sleeve with a hole penetrating the side surface is inserted into the output shaft with a spiral slot formed on the outer circumferential surface, and a ball is arranged so as to engage both the hole and the slot. Accordingly, since the sleeve is made to slide in the axial direction while rotating with respect to the output shaft, the rolling motion of the balls can cause both rotational motion and axial motion with small motion resistance.

(4) A ball bearing is inserted into the sleeve and a pin is fixed to the outer race side to drive the valve, so the movement of the sleeve can be transmitted to the valve only in the axial direction, and
Since the inner race is disposed to close the hole in the sleeve, it restricts the balls from moving radially outward and allows the balls to be constantly engaged with the slots.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway cross-sectional view showing a conventional embodiment;
Fig. 2 is a sectional view showing a conventional valve mechanism, Fig. 3 is a sectional view showing an embodiment of the present invention, Fig. 4 is a view showing a sleeve, and Fig. 5 is taken along line V-V in Fig. 3. 6 is an explanatory view showing the relationship between the wormshaft and the protrusion, and FIG. 7 is an explanatory view showing the rotary valve. 31...Stubshaft, 31a...Protrusion,
32... Steering shaft, 33... Housing, 37... Wormshaft, 39... Torsion bar, 44... Sleeve, 45... Hole, 4
6...Pin, 48...Ball bearing, 51...
...Ball, 52...Slot, 53...Cylinder housing, 66...Spool valve, 67...
pin.

Claims (1)

[Scope of Claims] 1. An input shaft connected to a steering shaft, an output shaft connected to this input shaft via a torsion bar, a slot formed in a spiral shape on the outer peripheral surface of this output shaft, A sleeve is provided on the outer periphery of the output shaft so as to be able to rotate together with the input shaft and to be slidable in the axial direction, a hole passing through the side surface of the sleeve, and a sleeve that engages with the hole and the slot; A ball that slides the sleeve in the axial direction in response to relative rotation between the input shaft and the output shaft, a ball bearing attached to the outer periphery of the sleeve such that an inner race closes the hole, and a ball bearing of the ball bearing. and a valve that is engaged with the outer race by a pin and is provided to switch the fluid path to the hydraulic means that operates the gear means for wheel steering as the sleeve slides. A distinctive power steering device. 2. The power steering device according to claim 1, wherein the valve is actuated via a pin fixed to the outer race.