JPS6158346B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in power steering devices.

Conventionally, as a power steering device, a recirculating ball type and a rack and pinion type are generally used.

As a rack-and-pinion type power steering device, a moving spool that can freely rotate and move in the axial direction is provided with a pawl, and this pawl is engaged with a spiral groove and slid in the axial direction, so that the moving spool can be moved axially. A system has been proposed in which the oil path is switched by moving the oil passage in the same direction. However, in this conventional technology, the pawl is of a fixed type and cannot be changed once set, so the pawl may slide along the groove surface unless the groove surface of the spiral groove is formed extremely precisely. On the other hand, if the distance between the groove surface and the pawl is increased in order to avoid this problem, there is a drawback that the responsiveness of the power steering device deteriorates by the time it takes to absorb the gap.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art, and provides a power steering device that can smoothly switch oil passages using a valve spool in proportion to steering reaction torque. The purpose is to

To achieve the objective, the power steering device of the present invention is rotatably mounted within the valve housing,
and an input shaft in which a first track is formed on the outer peripheral surface and has a track surface inclined at a predetermined angle with respect to the axis;
an output shaft connected to the input shaft via a torsion bar and rotatably mounted on the same axis as the input shaft; and a valve disposed concentrically with the input shaft and movably mounted in the axial direction. spool and
a sleeve disposed concentrically with the input shaft, coupled to the valve spool, and provided with an engagement hole on a side surface for engagement with a ball rolling on a first orbit of the input shaft; a pressing means disposed on the outer periphery to always elastically press the ball against the raceway surface of the first raceway; and a pressing means provided between the sleeve and the output shaft to allow the sleeve to move in the axial direction of the output shaft. and forming a second raceway having a raceway surface along the axial direction on the one member so as to prohibit relative rotation with the output shaft, and a fitted body that slides the raceway surface on the other member. and an engaging means provided.

The present invention will be further described below with reference to embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a power steering device according to the present invention. As is clear from the figure,
The power steering device of this embodiment is of a rack-and-pinion type, and inside the valve housing 1 is a hollow main shaft (input shaft) for steering.
2 is arranged, and the main shaft 2 is rotatably connected to a pinion shaft (output shaft) 5 in the pinion housing 4 in the same direction by a torsion bar 3 provided therein, and the pinion shaft 5 is connected to the pinion shaft (output shaft) 5 in the same direction. It is designed to mesh with the rack bar 6 at a pinion provided on the outer periphery. The main shaft 2 is positioned by the torsion bar 3 fixed by two left and right needle bearings 7 and left and right pins 8. Further, the pinion shaft 5 is positioned within the pinion housing 4 without play by two angular bearings 9 on the left and right sides.

The inside of the valve housing 1 is sealed by seals 10, 10 and a seal ring 12 held by a spacer 11, but oil from a pump (not shown) flows into the inside of the valve housing 1 through an opening 1a in the direction of arrow A. The oil is supplied to the reservoir (not shown) through another opening 1b. Furthermore, oil passages within the valve housing 1 are connected to each cylinder chamber of the cylinder as shown by arrows C and D.

The main shaft 2 has an enlarged part 2a near the end on the pinion shaft 5 side, and this enlarged part 2a has two spiral ball grooves 13 (first ) is formed (see Figures 2 and 3).

On the other hand, main shaft 2 and pinion shaft 5
A sleeve 14 is disposed on the outer periphery of the connecting portion with both shafts 2 and 5 so as to be able to rotate and move in the axial direction coaxially, and a ball 15 is fitted into the sleeve 14 at a symmetrical position on the circumference. 15 is fitted into the ball groove 13. ball 15
As will be explained later, the shaft rotates within the ball groove 13 and moves to both sides of the main shaft 2 in the axial direction.

As is clear from FIGS. 1 and 4a and 4b, the sleeve 14 has notches 16 (second tracks) in the axial direction on both sides in the diametrical direction at the end on the pinion shaft 5 side. By inserting a pin 17 (fitting body) fixed to the pinion shaft 5 into the portion 16, the sleeve 14 and the pinion shaft 5 are transmission-connected to the pinion shaft 5 so that rotational motion can be transmitted between the sleeve 14 and the pinion shaft 5. Therefore, the sleeve 14 cannot rotate relative to the pinion shaft 5, but can only move in the axial direction. Here, the notch 16 and the pin 17 are connected to the sleeve 1.
4 and the output shaft 5 constitute an engagement means.

A ring-shaped ring 18 for holding the ball 15 is provided on the outside of the ball 15, and the inner circumferential surface of the ring 18 is tapered. The one on the left is smaller than the one on the left. Further, the ring 18 is pushed toward the left in FIG. 1 by a spring 19. Therefore,
This tapered surface allows the ball 15 to move into the ball groove 1.
Since it is always pressed against the groove surface of No. 3 without any gaps, the responsiveness of the steering becomes very good.

Here, the ring 18 and the spring 19 constitute a pressing means for always elastically pressing the ball against the raceway surface of the first orbit.

On the other hand, the other end of the sleeve 14 (the left end as seen in FIG. 1) has claws 20 at two positions corresponding to the notches 16, as shown in FIGS. 1 and 4 a and b. The protruding pawl 20 fits into a circumferential groove on the outer periphery of a valve spool 21, thereby connecting the sleeve 14 and the spool 21.

The spool 21 is used to switch oil passages within the valve housing 1, and therefore, the spool 21 is arranged so as to be movable in the axial direction.

The axial positioning of the oil groove of the spool 21 and the valve housing 1 can be adjusted by changing the thickness of the spacer 11, and the spacer 11 is positioned by the ring 12.

In addition, two notches are formed on the circumference of the spool 21 on the left side in the axial direction (FIG. 1), and a protrusion 23 provided integrally with the spacer 22 is fitted into the notch. The protrusion 23 allows the spool 2 to
1 is prevented from rotating, and the sleeve 14 and spool 2 are
The integral rotation of 1 prevents unnecessary friction from occurring.

As shown in FIGS. 1 and 2, on the right side of the main shaft 2 in the axial direction (as seen in FIG. 1), there is a 2-way shaft located at a position rotated by 90 degrees from the ball groove 13.
A notch 24 is formed at several locations, and a protrusion 2 integrally provided on the pinion shaft 5 is formed in the notch 24.
5 are installed with a certain gap in the circumferential direction. These notches 24 and protrusions 25 are used to prevent excessive twisting of the torsion bar 3 during torque transmission, and to prevent the protrusions 25 from hitting the wall of the notch 24 when manual operation is required due to a failure of the hydraulic system. It is intended to enable torque from the main shaft 2 to be transmitted to the pinion shaft 5.

Next, the operation of this embodiment will be explained. When performing a steering operation, the reaction torque T' from the tires is transmitted to the pinion shaft 5 via the rack bar 6, and the torsion bar 3 is twisted in accordance with the reaction torque T', causing the main shaft 2 to respond to the rotational torque T. Rotate with.

At this time, the sleeve 14, which is transmission-coupled to the main shaft 2 by the ball 15, tries to rotate in the same way as the main shaft 2, but the pin 17 fixed to the pinion shaft 5 is inserted into the notch 16 of the sleeve 14. The ball groove 13 cannot rotate freely because of the notch 1.
Ball 1 is twisted at a certain angle relative to 6.
5 moves in the axial direction of the main shaft 2 while sliding within the ball groove 13 according to the rotational direction of the main shaft 2, and is guided by the ball groove 13 and moves in the axial direction of the main shaft 2.
As the sleeve 14 moves in the axial direction, the spool 21 connected to the sleeve 14 also moves in the axial direction, and the oil flowing from the pump into the valve housing 1 through the opening 1a flows from the opening 1b to the reservoir as shown by arrow B. (not shown), the opening 1b is closed to prevent oil from flowing out, and oil is supplied to one of the cylinder chambers as indicated by arrows C or D to increase the oil pressure in the cylinder chamber, thereby controlling the steering operation. This allows for extremely smooth and highly responsive steering operations. Note that the spool 21 in FIG. 1 is shown in a neutral position.

Furthermore, when the main shaft 2 is rotated with a constant torque, the main shaft 2, pinion shaft 5, and sleeve 14 try to rotate together, but the notch of the spool 21 prevents the protrusion 23 of the spacer 22 from rotating. The action does not cause rotation, but only axial movement.

In this embodiment, when adjusting the left and right difference in oil pressure, adjust the oil pressure while looking at the spacer 11, select the thickness of the spacer 11 based on it, and adjust the oil groove of the spool 21 and the valve housing 1 depending on the thickness of the spacer 11. The position can be adjusted in the axial direction, but another method is to insert the pin 8 shown at the left end of FIG. 1 last.
The spacer 11 can also be omitted. That is, if you look at the neutral position of the hydraulic pressure without inserting this pin 8, and insert the pin 8 when the neutral position is reached, the main shaft 2 and torsion bar 3 can be adjusted to the desired hydraulic pressure without using the spacer 11. It can be assembled with.

As explained above, according to the present invention, the relative rotation between the input shaft and the output shaft during steering is converted into axial movement via the ball rolling on the first orbit. The responsiveness of the valve spool is improved, and oil passages are switched smoothly. In addition, since the ball is always elastically pressed against the raceway surface of the first raceway by the pressing means, conversion from rotational displacement to axial displacement is performed linearly, so the assist force required during steering is instantaneously applied. This results in improved responsiveness. Furthermore, since the pressing means can be assembled after checking the mounting state of the ball from the outside of the sleeve before assembling it into the casing, it is possible to check for poor engagement between the ball and the raceway surface in advance. Since it is located in the center, assembly becomes easy and work efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the power steering device according to the present invention, FIG. 2 is a sectional view taken along the line -- in FIG. Figures 4a and 4b are a plan view and a front view of the sleeve, respectively. 2... Main shaft, 3... Torsion bar, 5... Pinion shaft, 13... Spiral ball groove, 14... Sleeve, 15... Ball, 16... Notch, 17... Pin, 18... Ring, 21...spool.

Claims (1)

[Claims] 1. Rotatably mounted within the valve housing,
and an input shaft having a first raceway formed on the outer peripheral surface thereof and having a raceway surface inclined at a predetermined angle with respect to the axis; connected to the input shaft via a torsion bar;
an output shaft rotatably mounted on the same axis as the input shaft; a valve spool disposed concentrically with the input shaft and movably mounted in the axial direction; and a valve spool disposed concentrically with the input shaft. a sleeve that is coupled to the valve spool and has an engagement hole on a side surface for engagement with a ball that rolls on a first orbit of the input shaft; a pressing means that constantly presses elastically against the raceway surface of the first raceway; and a pressing means provided between the sleeve and the output shaft to allow movement of the sleeve in the direction of the output shaft, and to allow movement of the sleeve relative to the output shaft. A second track having a track surface along the axial direction is formed on the one member so as to inhibit rotation, and an engaging means is provided in which the other member is provided with a fitting body that slides into contact with the track surface. power steering device.