JPS642546B2 - - 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 for controlling the supply and discharge of pressure fluid to and from a power cylinder is of a rotary type.

Generally, a rotary type control valve has a valve rotor that is integrally provided on an 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. and a valve sleeve, and when the valve is operated, the rotational displacement from the neutral state is caused between the input shaft and the output shaft, that is, between the valve rotor and the valve sleeve. , the direction of supply and discharge of pressure fluid to and from the power cylinder is controlled.

By the way, this type of power steering device has conventionally provided a piston that interlocks with the outer peripheral surface of the output shaft via a ball screw mechanism to convert the rotation of the output shaft into reciprocating motion of the piston. It is known that the reciprocating motion is transmitted to a sector gear that engages with a piston and rotates in forward and reverse directions. Conventionally, in this type of device, the input shaft and the output shaft are connected via a torsion bar, and the torsion force of the torsion bar is used to maintain the valve rotor and valve sleeve in a neutral state when not in operation. There is. However, due to the structure of this torsion bar, when the left and right torsional force is zero, the valve rotor and valve sleeve must be in a neutral state. It was impossible to grant it.

From this point of view, conventionally, in order to apply preload between the input and output shafts, a roughly C-shaped spring is used instead of a torsion bar, and the C-shaped spring is used to rotate protrusions that rotate integrally with each of the valve sleeve and the valve rotor. It has been proposed that the valve sleeve and the valve rotor are clamped to hold the valve sleeve and valve rotor in a neutral position. However, in the above-mentioned ball screw mechanism power steering device, the input and output shafts are usually connected by the torsion bar to prevent the input shaft from coming out of the housing, so a C-shaped spring is used instead of the torsion bar as described above. When used, separate means had to be provided to prevent it from coming off.

The present invention provides that, of a pair of projections held between a C-shaped spring, at least the projection on the input shaft side projects in the radial direction, and this projection comes into contact with a side surface of an inner race of a bearing that pivotally supports the input shaft. The input shaft can be stopped to prevent the input shaft from coming off.

The present invention will be described below with reference to the illustrated embodiments.
In Fig. 1, 1 is the input shaft, and this input shaft 1
and the output shaft 2 are disposed on the same axis, and a protrusion 3 protruding from the tip shaft of the input shaft 1 is rotatably attached to a bushing 4 fitted to the end shaft of the output shaft 2. In this state, the input shaft 1 and the output shaft 2 are inserted into the housing 5 from its open end side. The input shaft 1 and the output shaft 2 are the first
As shown in the figure, the projections 3 are connected in the rotational direction via an interlocking mechanism 6 formed at the proximal end position.
This interlocking mechanism 6, like the conventionally known interlocking mechanism between the input and output shafts 1 and 2, allows relative rotation between the input and output shafts 1 and 2 within a certain range, and does not allow relative rotation beyond that range. When this happens, the two shafts 1 and 2 are mechanically connected and interlocked.
The input shaft 1 is interlocked with a steering wheel (not shown), while the output shaft 2 is slidably housed in the housing 5 via a ball screw mechanism 7 having balls 7a, as shown in FIG. piston 8
linked to. The piston 8 reciprocates within the housing 5 with a constant stroke as the output shaft 2 rotates forward and backward. A rack 8a is provided at the bottom of the piston 8 in FIG. A sector gear 9 interlocked with a steering wheel (not shown) is engaged with the rack 8a, and is configured to rotate forward and backward as the piston 8 reciprocates. Further, as shown in FIG. 1, pressure chambers 5a and 5b are formed on both sides of the piston 8 of the housing 5, and the piston 8 is provided with a control valve to be described later in each of these pressure chambers 5a and 5b. An auxiliary force is provided by pressure fluid supplied through the auxiliary force.

As shown in FIG. 1, a cylindrical valve rotor 10 is integrally fitted and fixed on the outer peripheral surface of the distal end of the input shaft 1 closer to the proximal end than the interlocking mechanism 6 through a pin 10a. Further, a valve sleeve 11 is formed in the cylindrical portion of the output shaft 1 corresponding to the valve rotor 10, and furthermore, a valve sleeve 11 is formed on the outer peripheral surface side of the valve sleeve 11, and this portion is attached to the open end of the housing 5. An end block 12 that closes the is slidably connected. The valve rotor 10 and the valve sleeve 11 basically constitute a conventionally known rotary type control valve. An inner race 13a of a bearing 13 that rotatably supports the output shaft 2 is integrally provided on the outer peripheral surface of the right end portion of the output shaft 2 in FIG. 1, and an outer race 13b of the bearing 13 is integrally provided.
is installed in the end block 12 with one side in contact with the stepped portion 12a of the end block. The other side surface of the outer race 13b is pressed by the tip of a stopper 14 screwed onto the end of the end block 12, and is clamped and fixed between the stepped portion 12a and the stopper 14. The stop member 14 is prevented from loosening by a nut 15 screwed onto the end of the stop member 14 and a stop pin 16 inserted through the end of the stop member 14, as shown in FIG. ,
Further, the outer surfaces of the stopper member 14, the nut 15, etc. are covered with a cover body 17 attached to the input shaft 1.

The outer surface of the inner race 13a of the bearing 13 is provided with an axial protrusion 18 that protrudes in the axial direction, as shown in FIG. Radial projection 19
are provided, and these protrusions 18, 19 are held between both end surfaces of a notch 20a of a C-shaped spring 20 disposed on the outer peripheral surface of the input shaft 1, as shown in FIGS. 1 and 2. . A notch 1a is provided in the peripheral surface portion of the input shaft 1 corresponding to the axial projection 18, as shown in FIG.
Contact with 8 is prevented. Note that the circumferential spacing of the notches 20a in the C-shaped spring 20 in its natural state, that is, before it is attached to the input shaft 1, is as follows:
The length of each projection 18, 19 in the same direction is set to be smaller than that of the C-shaped spring 20.
By sandwiching both the protrusions 18 and 19, a desired preload is applied between the input and output shafts 1 and 2. As a result, the input/output shafts 1 and 2 are reliably maintained in an accurate neutral state.

On the other hand, as shown in FIG. 1, a large diameter portion 21 having a required width in the axial direction is formed in a portion of the input shaft 1 closer to the proximal end than the position of the radial protrusion 19. , is rotatably supported by a bearing 22 disposed on the stepped portion 14a of the stop member 14, and an annular recess 21a is formed on the outer surface of the large diameter portion 21, and the bearing 22 is provided in the recess 21a. Packing 23 is arranged in a state where it is partially wrapped in the axial direction. Further, on the inner surface of the inner race of the bearing 22, as shown in FIG.
The radial projections 19 are contacted and locked, and the radial projections 19 prevent the input shaft 1 from coming off the output shaft 2. By using the radial protrusion 19 also as a thrust stopper for the input shaft 1, the structure is simplified compared to the case where a separate thrust stopper is additionally provided, and it becomes possible to reduce the size in the axial direction.

In a neutral state, the control valve composed of the valve rotor 10 and the valve sleeve 11 simply circulates pressure fluid from a pump (not shown). That is, as shown in FIGS. 1 and 3, pressurized fluid from the pump is supplied to the valve through a supply hole 30 formed in the end block 12, an annular groove 31 formed in the valve sleeve 11, and a radial passage 32, respectively. An axial shaft 3 is formed on the inner surface of the valve sleeve 11 so that it can flow into the axial supply groove 33 formed on the rotor 10 and overlap both sides of the groove 33 in the circumferential direction.
4, 35, and an axial discharge groove 36 formed in the valve rotor 10 so as to overlap both grooves 34, 35.
flow inside. The pressure fluid that has flowed into the discharge groove 36 is transferred to the radial groove 3 provided in the valve sleeve 11.
7 and the discharge hole 3 of the end block 12 through the annular groove 38 provided on the inner peripheral surface of the end block 12, respectively.
9 to the suction side of the pump, and
The bush 4, the interlocking mechanism 6, both bearings 13, 22,
and the C-shaped spring 20 portion.

Grooves 34 and 35 located on both sides of the supply groove 33
One of the grooves 34 communicates with one pressure chamber 5a of the housing 5 through a radial passage 42, and the other groove 35 communicates with the other pressure chamber 5b through a passage (not shown). However, in the neutral state, the respective flow path areas of the supply groove 33 and the grooves 34 and 35 on both sides thereof are substantially equal, and both grooves 34 and 3
5, the power cylinder, that is, the piston 8 remains inactive.

On the other hand, when the input shaft 1 rotates in one direction, the force between the two protrusions 18 and 19 resists the elastic force of the C-shaped spring 20.
Therefore, relative rotation occurs between the valve rotor 10 and the valve sleeve 11, and a difference occurs in the flow area between the supply groove 33 and the grooves 34 and 35 on both sides of the supply groove 33 depending on the direction of rotation. Accordingly, a pressure difference is generated between both grooves 34 and 35. As a result, a pressure difference is generated between the pressure chambers 5a and 5b communicating with both grooves 34 and 35, respectively, and the piston 8 is actuated to apply an auxiliary force in the steering direction as is conventionally known.

In the above embodiment, separate pins are implanted in the input shaft 1 and the output shaft 2, and the protrusion 1
8 and 19, but the input/output shafts 1 and 2 are formed with protrusions integral with these, and the protrusion 1
It may also be 8 or 19. Further, the present invention can be applied not only to the power steering device having the illustrated ball screw mechanism but also to other power steering devices.

As described above, in the present invention, the protrusion that rotates integrally with each of the input and output shafts is held in a neutral position by being held in a neutral position by using a C-shaped spring, and the protrusion on the input shaft side is made to protrude in the radial direction. The directional protrusion is arranged on the outer peripheral surface of the input shaft and is brought into contact with the side surface of the inner race of the bearing that rotatably supports the input shaft, thereby preventing the input shaft from slipping out. , there is no need to specially provide a thrust stopper for the shaft, and therefore the structure can be significantly simplified and the size can be reduced in the axial direction.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a sectional view taken along the - line in FIG. 1. 1: Input shaft, 2: Output shaft, 6: Interlocking mechanism, 7:
Ball screw mechanism, 8: Piston, 9: Sector gear, 10: Valve rotor, 11: Valve sleeve, 18:
Axial projection, 19: Radial projection, 20: C-shaped spring, 21: Large diameter portion, 21a: Recessed portion, 22: Bearing, 23: Packing.

Claims (1)

[Scope of Claims] 1. An input shaft interlocked with a steering wheel, an output shaft disposed on the same axis as the input shaft and interlocked with steering wheels, and a control valve element provided on each of the two shafts. and a rotary type control valve that controls the supply and discharge of pressure fluid to and from the power cylinder according to the relative rotational displacement of both control valve elements, the power steering device rotates integrally with the input shaft and protrudes in the radial direction. a radial protrusion that rotates integrally with the output shaft; both protrusions are held by a roughly C-shaped spring to hold both control valve elements in a neutral position; A power steering device characterized in that the input shaft is prevented from coming off by contacting and locking the radial protrusion to a side surface of an inner race of a bearing that is disposed on an outer circumferential surface and rotatably supports the shaft. 2. The bearing mounting portion of the input shaft is constructed as a large diameter portion, and an annular recess is provided on the side surface of the large diameter portion, and a packing is disposed in the recess, so that at least a portion of the packing and the bearing are connected. 2. The power steering device according to claim 1, characterized in that the two are superimposed in the axial direction.