JPS6351907B2 - - 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 in which a control valve that controls the supply and discharge of pressure fluid to and from a power cylinder is of a rotary type.

A rotary control valve usually has a valve rotor that is integrally provided on the input shaft on the steering wheel side and an output shaft on the steering wheel side that can rotate around the outer circumference of the valve rotor. When the valve sleeve is operated, pressure fluid is supplied to the power cylinder according to the direction of relative rotational displacement from the neutral state caused between the input shaft and the output shaft, that is, between the valve rotor and the valve sleeve. Controls supply/discharge direction. Conventionally, the input shaft and the output shaft are connected via a torsion bar, and the torsion force of the torsion bar allows the valve rotor and valve sleeve to be maintained in a neutral state when the valve is not in operation. However, due to its structure, the torsion bar must be in a neutral state between the valve rotor and the valve sleeve when the torsion force in the left and right directions is zero.
Therefore, it has been impossible to apply preload between the input and output shafts using a torsion bar.

For this reason, conventionally, in addition to or in place of the above-mentioned torsion bar, a C-shaped spring is used, for example, which is formed into a roughly C-shape by cutting out a part of a ring-shaped spring material, and the input shaft is connected between the notches of the C-shaped spring. A power steering device has been proposed in which a protrusion that is integrated with the output shaft is simultaneously clamped with a predetermined elastic force, thereby making it possible to maintain both shafts in a neutral state and at the same time apply preload. has been done.

However, when the pair of protrusions are held between the C-shaped springs, it is necessary to place each protrusion in a predetermined position with extremely high precision with respect to the valve rotor or valve sleeve. If one of the protrusions is misaligned in the circumferential direction, the valve rotor and valve sleeve will be assembled in a position deviated from the normal neutral position when both protrusions are clamped by a C-shaped spring. Generally, it is difficult to correct the positional deviation of the upper projection, and if the amount of deviation exceeds the normal range, it is discarded.

In view of these points, the present invention provides a rotary type system in which, when a discrepancy occurs in the circumferential direction between a pair of engaging parts such as a pair of protrusions, both engaging parts are held in the displaced state by a spring. Focusing on the fact that the neutral position of the control valve can be ensured, a small modification is made to the spring, and the modified spring holds both engaging portions in a shifted state.

The present invention will be described below with reference to the illustrated embodiments.
In FIG. 1, the input shaft 1 and the output shaft 2 are arranged on the same axis, and the protrusion 3 protruding from the tip shaft of the input shaft 1 is fitted into the distal shaft of the output shaft 2. The input shaft 1 and the output shaft 2 are rotatably fitted into the bush 4, and in this state, the input shaft 1 and the output shaft 2 are rotatably supported in the housing 5 via a bearing 6. The input shaft 1 is linked to a steering wheel (not shown), while a helical pinion 7 is attached to the tip of the output shaft 2.
This pinion 7 is meshed with a rack that is linked to a steering wheel (not shown), similar to a conventionally known rack and pinion type power steering device.

As shown in FIGS. 1 to 4, a substantially rectangular engagement portion 8 is provided at the tip of the input shaft 1 in front of the protrusion 3.
However, the output shaft 2 is also formed with a groove 9 for receiving the engaging portion 8, and the engaging portion 8 is disposed within the groove 9 with a required gap in the circumferential direction. Therefore, the input shaft 1 and the output shaft 2 can rotate relative to each other by an amount allowed by the gap therebetween. Protrusions 10 and 11 are provided in the vicinity of the engaging portion 8, that is, the input shaft 1, and the groove 9, that is, the output shaft 2, respectively. Engaging portions 12a and 12b of the C-shaped spring 12 provided
It is held between both end faces.

At this time, the circumferential gap l between the engaging portions 12a and 12b of the C-shaped spring 12 in its natural state (see FIG. 2) is set to be smaller than the length of each protrusion 10 and 11 in the same direction, Therefore, by sandwiching both the protrusions 10 and 11 with this C-shaped spring 12, a desired preload can be applied between the input and output shafts 1 and 2. Also, a pair of engaging portions 12a, 12b of the C-shaped spring 12
are formed to be slightly shifted in the circumferential direction, and the amount of shift L is determined by the circumference between the protrusions 10 and 11 when the valve rotor 13 and the valve sleeve 14, which will be described later, are accurately placed in the neutral position. It matches the amount of deviation in direction.

In other words, the pair of engaging portions 12a and 12b are
After measuring the amount of deviation in the circumferential direction between the two protrusions 10 and 11 when the valve rotor 13 and valve sleeve 14 are accurately placed in the neutral position, the amount of deviation L is made to match the amount of deviation. The engaging portion 12 is formed on the spring 12 and therefore has a displacement L.
If both protrusions 10 and 11 are held between a and 12b,
The valve rotor 13 and the valve sleeve 14 are accurately maintained in a neutral state when no external force is applied to the input/output shafts 1 and 2. In this state, the engaging portion 8 is held at approximately the center position of the groove 9 in the circumferential direction.

However, the valve rotor 1 is directly connected to the input shaft 1.
3 is formed, and a valve sleeve 14 is rotatably fitted around the outer periphery of this valve rotor 13, basically forming a conventionally known rotary type control valve.
The end portion of the valve sleeve 14 on the output shaft 2 side is formed as a cylindrical portion 14a that can be fitted into the portion 2a of the output shaft 2 provided with the protrusion 11. An axial engagement groove 15 having a width corresponding to the width of the groove 15 and a through hole 16 that allows the protrusion 10 to pass therethrough and allow the protrusion 10 to be displaced in the circumferential direction are formed. The cylindrical portion 14a is located inside the C-shaped spring 12 as shown in FIGS. are integrally connected in the rotational direction, and the protrusion 10
are loosely fitted through the through hole 16 at least on both sides in the rotational direction with a predetermined interval. In addition, the above C
The shaped spring 12 is held between a spacer 17 provided on the step 2b of the output shaft 2 and the step 14b of the valve sleeve 14.

In the neutral state, the control valve composed of the valve rotor 13 and the valve sleeve 14 simply circulates pressure fluid from a pump (not shown). That is, the pressure fluid from the pump is
As shown in the figure, the flow flows into an axial supply groove 23 formed in the valve rotor 13 through a supply hole 20 formed in the housing 5, an annular groove 21 formed in the valve sleeve 14, and a radial passage 22, and further flows into the axial supply groove 23 formed in the valve rotor 13. Axial grooves 24 and 25 are formed on the inner surface of the valve sleeve 14 so as to overlap both sides of the groove 23 in the circumferential direction, and the valve rotor 1 is formed so as to overlap both grooves 24 and 25.
3 into the axial discharge groove 26 formed at 3.
The pressure fluid that has flowed into the discharge groove 26 flows along the groove toward the abutting portion of the input shaft 1 and output shaft 2, and from there flows into the through hole 16 and the engaging portion 12a of the C-shaped spring 12, 12b to the outer periphery of the valve sleeve 14, and further flows back to the suction side of the pump via a discharge hole 27 provided in the housing 5. The groove 24 on one side of the supply groove 23 communicates with one chamber of the power cylinder (not shown) via a radial passage 28, an annular groove 29, and a supply/discharge hole 30 provided in the housing 5, and similarly the groove 24 on the other side 25 also communicates with the other chamber of the power cylinder through a radial passage 31, an annular groove 32, and a supply/discharge hole 33, but in the neutral state, the supply groove 23 and the grooves 2 on both sides thereof
4 and 25 are substantially equal, and no pressure difference occurs between both grooves 24 and 25, the power cylinder maintains a non-operating state.

On the other hand, when the input shaft 1 is rotated in one direction, both protrusions 10,
Therefore, relative rotation occurs between the valve rotor 13 and the valve sleeve 14, and a difference occurs in the flow path area between the supply groove 23 and the grooves 24 and 25 on both sides thereof depending on the direction of rotation. Along with this, both grooves 24, 2
A pressure difference occurs between the two. As a result, both grooves 24, 2
Power cylinders communicating with each of the steering wheels 5 are actuated to provide an auxiliary force in the steering direction, as is well known in the art.

6 and 7 respectively show springs 40 and 41 having other configurations, one engaging portion 40a of the spring 40 has a recess along the outer periphery of the protrusion 10 on one side in the circumferential direction. , the other engaging portion 40b has a recess along the outer periphery of the protrusion 11 on the other side in the circumferential direction,
A predetermined amount of deviation L is obtained by adjusting the depth of each recess. The spring 41 also has a pair of engaging portions 41a and 41b diagonally with respect to the axial direction.
The above deviation amount L is obtained by forming .

In each of the above embodiments, the protrusions 10 and 11 are connected to the spring 1
2, 40, and 41, but the structure is not limited to this, and appropriate design changes can be made in accordance with the structure of other conventionally known rotary type control valves.

As described above, the present invention provides an input shaft linked to a steering wheel, an output shaft installed on the same axis as the input shaft and linked to steering wheels, and each of the input shaft and output shaft. A rotary type control valve that controls the supply and discharge of pressure fluid to the power cylinder according to the relative rotational displacement of both control valve elements; and a spring that engages and biases both the engaging parts to hold the engaging parts in a predetermined relative non-operating position, and the spring engages with each of the engaging parts of the spring. Each of the engaging portions is shifted in the circumferential direction by an amount corresponding to the amount of circumferential deviation between the two engaging portions when the pair of control valve elements are in a neutral position. This has the effect that both engaging parts, that is, both control valve elements, can be held in accurate neutral positions by simply making corrections to the pre-prepared springs according to the above-mentioned amount of deviation. can get.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is an exploded perspective view of the main parts of FIG. 1, and FIG.
A sectional view taken along the - line in the figure, Figure 4 is A of Figure 3.
5 is a sectional view taken along the - line in FIG. 1, and FIGS. 6 and 7 each show other embodiments of the present invention, and are plan views of the same parts as in FIG. 5. It is. 1: input shaft, 2: output shaft, 10, 11: protrusion,
12, 40, 41: Spring, 12a, 12b, 40
a, 40b, 41a, 41b: engaging portion, 13:
Valve rotor, 14: Valve sleeve, L: Displacement amount.

Claims (1)

[Claims] 1. An input shaft linked to a steering wheel, an output shaft disposed on the same axis as the input shaft and linked to steering wheels, and a pair of control valve elements provided on each of the input shaft and output shaft. a rotary type control valve that controls the supply and discharge of pressure fluid to the power cylinder according to the relative rotational displacement of both control valve elements, and an engagement portion integrally provided in each of the control valve elements; a spring that engages and biases both engaging portions to hold the engaging portions in a predetermined relative non-operating position; A power steering device characterized in that a pair of control valve elements are shifted in a circumferential direction by an amount corresponding to a circumferential shift amount between both engaging portions when the pair of control valve elements are in a neutral state position.