JPS642545B2 - - 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 in which pressure fluid is supplied and discharged 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 the torsion bar, the valve rotor and valve sleeve must be in a neutral state when the left and right torsional forces are zero, and for this reason, it is impossible to apply preload between the input and output shafts with the torsion bar. It is. In addition, when using a torsion bar, it is necessary to place the torsion bar at the center of the input and output shafts, which requires boring the input and output shafts, making machining work difficult. There are disadvantages such as a decrease in the strength of the control valve position.

The present invention was made in order to solve such conventional problems, and its purpose is to be able to apply preload between the input and output shafts, and to accurately and reliably maintain the neutral state of the control valve. To provide a power steering device capable of providing sharp steering characteristics with little play.

The present invention provides a radial protrusion integral with one control valve element and protruding in the radial direction, an axial protrusion integral with the other control valve element and protruding in the axial direction, and both protrusions. is held between roughly C-shaped springs to maintain the input shaft and output shaft in a neutral state, and in this neutral state, the gap in the rotational direction between both end surfaces of the spring and both protrusions is substantially zero. It is characterized by:

The present invention will be described below based on illustrated embodiments.

In FIG. 1, 1 is an input shaft, and the input shaft 1 and output shaft 2 are arranged on the same axis.
A protrusion 3 protruding from the distal end shaft of the input shaft 1 is rotatably fitted into a bushing 4 fitted to the distal end shaft of the output shaft 2, and the input shaft 1 and the output shaft 2 are connected to each other. In this state, it is inserted into the housing 5 from its open end side. And input shaft 1 and output shaft 2 are
As shown in FIG. 1, the projections 3 are connected in the rotational direction via an interlocking mechanism 6 formed at a proximal 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 interlocked.
The input shaft 1 is linked to 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. It is linked to piston 8. The piston 8 is configured to reciprocate within the housing 5 with a constant stroke as the output shaft 2 rotates in the forward and reverse directions. At the bottom of this piston 8 in FIG.
A sector gear 9 which is interlocked with a steering wheel (not shown) is engaged with the rack 8a, and is rotated 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 has a control valve, which will be described later, in each of these pressure chambers 5a and 5b. An auxiliary force is applied 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
Thus, 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 12. 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. This stopper member 14
As shown in the figure, loosening is prevented by a nut 15 screwed onto the end of the stop member 14 and a stop pin 16 inserted from the end of the stop member 14. The outer surface of the input shaft 15 and the like is 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
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. Further, the axial protrusion 18 of the input shaft 1
As shown in FIG. 2, a notch 1a is provided in the peripheral surface portion corresponding to the axial projection 18 to prevent contact with the axial projection 18. Note that the circumferential interval l of the cutout portions 20a of the C-shaped spring 20 in its natural state is:
As shown in FIG. 3, the lengths of the respective protrusions 18 and 19 in the same direction are set to be smaller than each other. A desired preload is applied between the two. Furthermore, both end surfaces of the notch 20a of the C-shaped spring 20 in the natural state are parallel to each other as shown in FIG. Both end surfaces of the notch 20a are inclined surfaces whose distance gradually increases toward the outside. Here, since the axial center of the axial protrusion 18 is located at the center in the thickness direction of the C-shaped spring 20 as shown in FIGS. 2 and 4, both the protrusions 18
When the widths of 8 and 19 in the rotation direction are made the same,
In a state where no external force is applied to the input/output shafts 1 and 2, that is, in a neutral state of the control valve, the axial protrusion 18 does not come into contact with the notch 20a of the C-shaped spring 20 on both end surfaces. Therefore, in the present invention, as shown in FIG. 4, the width of the axial protrusion 18 in the rotational direction is made larger than that of the radial protrusion 19. In the neutral state of the control valve, both protrusions 18 and 19 come into contact with points B and C on both end faces of the notch 20a, respectively, as shown in FIG.
2 is reliably held in a precise neutral state.

On the other hand, on the proximal end side of the input shaft 1 from the position of the radial protrusion 19, a large diameter portion 21 having a required width in the axial direction is formed as shown in FIG.
is rotatably supported by a bearing 22 disposed on the stepped portion 14a of the stop member 14, and the large diameter portion 2
An annular recess 21a is formed on the outer surface of 1,
A packing 23 is disposed in this concave portion 21a so as to partially overlap the bearing 22 in the axial direction. Further, as shown in FIG. 1, the radial protrusion 19 is contacted and engaged with the inner surface of the inner race of the bearing 22, thereby preventing the input shaft 1 from coming off the output shaft 2.

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, the 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, as shown in FIGS. 1 and 5. Flows into the axial supply groove 3 formed in the rotor 10,
Furthermore, an axial shaft 34 is formed on the inner surface of the valve sleeve 11 so as to be able to overlap on both sides of the groove 33 in the circumferential direction.
35 and into an axial exhaust groove 36 formed in the valve rotor 10 so as to overlap both grooves 34, 35. The pressure fluid flowing into the discharge groove 36 is transferred from the discharge hole 39 of the end block 12 to the pump via a radial groove 37 provided in the valve sleeve 11 and an annular groove 38 provided in the inner peripheral surface of the end block 12, respectively. While flowing back to the suction side, the pressure fluid flows from the discharge groove 36 to the radial groove 40 provided in the valve rotor 10 and the radial groove 4 provided in the valve sleeve 11.
1 respectively, the bushing 4, the interlocking mechanism 6,
Both bearings 13, 22 and the C-shaped spring 20 portion are also supplied.

Grooves 34 and 35 located on both sides of the supply groove 33
One of the grooves 34 communicates with the pressure chamber 5a of the housing 5 via a radial passage 42, and the other groove 35 communicates with the other pressure chamber 5b via a passage (not shown). In the neutral state, the flow area of the supply groove 38 and the grooves 34, 35 on both sides thereof are substantially equal, and no pressure difference occurs between the two grooves 34, 35, so the piston 8 maintains the non-operating state. ing.

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, the notch 20 of the C-shaped spring 20 in the natural state as shown in FIG.
a C-shaped spring 20 with both end surfaces parallel to each other
As shown in FIG. 6, the C-shaped spring 200 has both end surfaces of the notch 200a forming an inclined surface in which the gap gradually narrows outward in the natural state. You may also use If such a C-shaped spring 200 is used, the C-shaped spring 2 can be attached to the input shaft 1 as shown in FIG.
00 is attached, both end surfaces of the notch 200a become parallel to each other, so that the radial protrusion 19 and the axial protrusion 18 can have the same diameter. Also, contrary to the above embodiment, the valve rotor 1 is connected to the output shaft 2.
0 and a valve sleeve 11 on the input shaft 1 respectively.

As described above, the present invention provides a radial protrusion that is integrated with one control valve element and projects in the radial direction, and also provides an axial protrusion that is integrated with the other control valve element and projects in the axial direction. , and both protrusions are held by roughly C-shaped springs to maintain the input and output shafts in a neutral state, so unlike when using a torsion bar, a preload is applied between the input and output shafts. Is possible. In addition, if the torsion bar is omitted, there is no need to perform boring on the input/output shaft, which makes processing easier and prevents the strength of the shaft from deteriorating.This makes it possible to achieve smaller size and lighter weight. . In addition, in the present invention, the gap in the rotational direction between both end surfaces of the spring that biases both protrusions from both sides in the rotational direction in the neutral state and both protrusions is substantially zero, so that the neutral state of the control valve can be accurately and reliably maintained. This allows for sharp steering characteristics with less play.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a view taken along the - line in FIG. Figure 4 is an explanatory diagram showing the notch of the C-shaped spring and both protrusions in a neutral state, and Figure 5 is the
6 is an explanatory diagram showing a modified example of the C-shaped spring in its natural state; FIG. 7 is an explanatory diagram showing the state of the C-shaped spring and both protrusions shown in FIG. 6 in a neutral state. It is a diagram. 1... Input shaft, 2... Output shaft, 6... Connection mechanism, 7... Ball screw mechanism, 8... Piston, 9
... Sector gear, 10 ... Valve rotor, 11 ... Valve sleeve, 18 ... Axial projection, 19 ... Radial projection, 20,200 ... C-shaped spring, 20a, 20
0a... Notch.

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. In a power steering device comprising a rotary type control valve that controls the supply and discharge of pressure fluid to and from a power cylinder according to the relative rotational displacement of both control valve elements, A radial protrusion is provided that protrudes from the other control valve element, and an axial protrusion that is integral with the other control valve element and protrudes in the axial direction is provided, and both protrusions are held by a roughly C-shaped spring to connect the input shaft and the output shaft. remain neutral, and
A power steering device characterized in that in this neutral state, a gap in the rotational direction between both end surfaces of the spring and both protrusions is substantially zero. 2. Claim 1, characterized in that the widths in the rotational direction of both protrusions are made different from each other, so that the gap in the rotational direction between both end faces of the spring and both protrusions is substantially zero.
The power steering device described in Section 1. 3. Claims characterized in that in a neutral state, both end surfaces of the spring are parallel to the radial protrusions, so that the gap in the rotational direction between both end surfaces of the spring and both protrusions is substantially zero. The power steering device according to item 1.