JPH06255508A - Power steering device - Google Patents

Abstract

PURPOSE:To enable the adoption of a large spring so as to improve the degree of freedom of spring specifications and the degree of design freedom of power steering characteristics by arranging the spring coaxially on the outer periphery of an input shaft above a valve sleeve. CONSTITUTION:Since an input shaft 12 and an output shaft 14 rotate relatively when a vehicle turns, a passage 16a of a valve sleeve 16 is shut off from one of a plural number of passages 16b, 16c and the other is shut off from a communicating groove 15b of a valve rotor 15. Consequently, hydraulic oil is supplied to one of a plural number of oil chambers C1, C2, hydraulic oil flows from the other oil chamber toward a tank T, and a power cylinder C operates. At the same time, as a plural number of cam followers 21 travel against a spring 24 along a three-dimensional cam 14b, this spring force works on a steering wheel as reaction force. The spring 24 is arranged coaxially on the outer periphery of the input shaft 12 above the valve sleeve 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus mounted on a vehicle.

[0002]

2. Description of the Related Art As one type of power steering apparatus, a valve rotor which is rotatably supported in a valve housing and rotates integrally with a first shaft, and a valve rotor which is coaxially rotatable with the first shaft by a predetermined amount. A valve sleeve that rotates integrally with the connected second shaft and is concentrically arranged on the outer periphery of the valve rotor;
A control valve mechanism provided between the valve sleeve and the valve rotor and capable of switching a supply / discharge passage for each oil chamber of the power cylinder is provided, and the control valve mechanism is operated by relative rotation between the two shafts to operate the power valve. In a power steering apparatus including a rotary valve type control valve for controlling supply and discharge of hydraulic oil to and from each oil chamber of a cylinder, a three-dimensional cam symmetrical with respect to a rotation direction is formed at one end of the first shaft,
A cam follower that engages with the three-dimensional cam and moves in the axial direction when the two shafts rotate relative to each other is attached to the second shaft so as to be axially movable and integrally rotatable, and the cam follower is provided in the second shaft. Japanese Patent Application Laid-Open No. 4-19268 proposes a structure in which the three-dimensional cam is biased toward the three-dimensional cam.

[0003]

In the conventional power steering apparatus described above, the desired power steering characteristics can be obtained by appropriately setting the spring specifications of the spring, but the spring is within the second shaft. However, since a large spring cannot be adopted, the degree of freedom of the spring specifications of the spring is limited, and the degree of freedom in designing the power steering characteristic is small. The present invention has been made to solve the above-described problem, and an object thereof is to provide a power steering apparatus that can employ a large spring and has a large degree of freedom in designing power steering characteristics.

[0004]

In order to achieve the above object, in the present invention, the power steering apparatus is a valve which rotates integrally with a first shaft rotatably supported in a valve housing. A rotor and a valve sleeve that rotates integrally with a second shaft that is coaxially and relatively rotatably connected to the first shaft and that is arranged concentrically on the outer periphery of the valve rotor, and the valve sleeve and the valve. A control valve mechanism provided between the rotors for switching the supply and discharge passages for each oil chamber of the power cylinder by relative rotation of the two shafts; a three-dimensional cam symmetrically formed at one end of the second shaft in the rotational direction; A cam follower that is axially movable and integrally rotatable with the first shaft and that engages with the solid cam and moves in the axial direction when the two shafts rotate relative to each other; and the valve sleeve on the first shaft side. A spring that is coaxially arranged on the outer periphery of the first shaft and that bends in the axial direction, and a connector that transmits the spring force of the spring to the cam follower and presses the cam follower toward the three-dimensional cam. And

[0005]

In the power steering apparatus according to the present invention, the spring is the first on the first shaft side of the valve sleeve.
It is arranged coaxially with the outer circumference of the shaft, that is, is formed between the partial outer circumference of the first shaft and the valve housing surrounding the first shaft at one end of the valve sleeve, and a partial shape change of the first shaft and the valve housing. Since the spring is placed in a space that can be made larger,
It is possible to employ a large spring, which improves the degree of freedom in the specifications of the spring and improves the degree of freedom in designing the power steering characteristics.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a vehicle rack and pinion type power steering apparatus. In this power steering apparatus, an input shaft 12 and a valve housing rotatably supported in a valve housing 11 are provided. An output shaft 14 rotatably supported in the gear housing 11 and the gear housing 13 is coaxially and rotatably connected by a predetermined amount. A discharge port 11a is formed in the valve housing 11 and is connected to the tank T.

The input shaft 12 is connected at its upper end to a steering wheel (both not shown) via an intermediate shaft and a main shaft, and a valve rotor 15 is integrally formed at the lower end thereof. A valve sleeve 16 is concentrically arranged on the outer circumference of the valve rotor 15. As shown in FIGS. 1 and 2, the valve rotor 15 has a passage switching groove 15a and a communication groove 15b on the outer periphery, and the passage switching groove 15a is closed at both upper and lower ends.
The upper and lower ends of the communication groove 15b are open. Further, a mounting groove 15c is formed at the lower end of the valve rotor 15 in the axial direction so as to extend in the radial direction through the shaft center, and a coupling shaft 22 for coupling the pair of cam followers 21 is axially formed in the mounting groove 15c. It is mounted so as to be movable and rotatable integrally. The cam followers 21 are rotatably assembled to the connecting rod 22 together with the shim plates 23, and are secured by an E-shaped clip 24.

As is well known, the valve sleeve 16 forms a control valve mechanism between the valve rotor 15 and the valve rotor 15 for switching the supply / discharge passages for the oil chambers C1, C2 of the power cylinder C by the relative rotation of the shafts 12, 14. It is integrally assembled to the upper end of the output shaft 14 so as to rotate integrally with the output shaft 14, and is connected to the hydraulic pump P through a supply port (not shown) formed in the valve housing 11. Passage 16a, and passages 16b, 1 connected to the oil chambers C1, C2 of the power cylinder C through the connection ports (not shown) formed in the valve housing 11 respectively.
6c.

The output shaft 14 is integrally provided with a pinion 14a which meshes with a rack 17 (which is integrally formed with the piston rod of the power cylinder C), and a pair of solid cams 14b are formed at the upper end thereof. Each solid cam 14b has a spring 24, a connecting tool 25, and a connecting shaft 2.
The cam followers 21 urged downward via 2 are engaged with each other. Each of the three-dimensional cams 14b is formed in a U shape, and an arc portion a for moving each cam follower 21 upward against the action of the spring 24 by the relative rotation of the input shaft 12 and the output shaft 14, and this arc portion. It is composed of straight line portions b formed at both ends of a and defining a maximum relative rotation amount of the input shaft 12 and the output shaft 14 to a predetermined amount.

The spring 24 is a compression coil spring which is coaxially arranged on the outer circumference of the input shaft 12 on the upper side of the valve sleeve 16 and bends in the axial direction.
It engages with the inner race 26a of the bearing 26 that pivotally supports 2 via the retainer 27, and also engages with the upper end ring portion 25a of the connector 25 at the lower end. Connector 25
Is composed of an upper end ring portion 25a, a pair of leg portions 25b, and a stopper 25c for positioning the spring 24, and is assembled to the outer periphery of the input shaft 12 so as to be vertically movable. Each leg portion 25b is a valve rotor. 15 communication grooves 1
5b, the upper end is engaged with the upper end ring portion 25a, and the lower end is engaged with the connecting shaft 22.

In the present embodiment constructed as described above, since the input shaft 12 and the output shaft 14 do not rotate relative to each other when the vehicle goes straight, the relationship between the three-dimensional cam 14b and the cam follower 21 is as shown in the drawing. The passage 16a of the valve sleeve 16 and the passages 16b, 16c and the valve rotor 15
The hydraulic oil supplied to the passage 16a from the hydraulic pump P is not supplied to the power cylinder C but to the tank 15 through the communication groove 15b of the valve rotor 15 and the discharge port 11a of the valve housing 11 because it is communicated with the communication groove 15b. Reflux to T.

However, when the vehicle turns, the input shaft 12
And relative rotation between the output shaft 14 and the valve shaft 1
The passage 16a of 6 is blocked from communicating with one of the passages 16b and 16c, and the other of the passages 16b and 16c is blocked from communicating with the communicating groove 15b of the valve rotor 15. The hydraulic oil is supplied to one of the oil chambers C1 and C2, and the hydraulic oil flows from the other of the oil chambers C1 and C2 toward the tank T to operate the power cylinder C to assist the turning steering force. It Further, at this time, since both cam followers 21 move along the three-dimensional cam 14b due to the relative rotation between the input shaft 12 and the output shaft 14 and move in the axial direction against the action of the spring 24,
The spring force of the spring 24 acts on the steering wheel as a reaction force.

By the way, in the present embodiment, the spring 24 is arranged coaxially with the outer periphery of the input shaft 12 above the valve sleeve 16, that is, at one end of the valve sleeve 16 a part of the input shaft 12 is provided. The input shaft 12 is formed between the outer circumference and the valve housing 11 surrounding the outer circumference.
Since the spring 24 is arranged in a space that can be appropriately enlarged by partially changing the shape of the valve housing 11 and the valve housing 11, a large spring can be adopted, the degree of freedom of spring specifications is improved, and the power is improved. The degree of freedom in designing steering characteristics is improved.

FIG. 3 shows another embodiment of the present invention.
In this embodiment, the connector 125 is used as a connector for transmitting the spring force of the spring 24 to the cam follower 21 through the valve rotor 15. Connector 125
Penetrates through the upper end ring portion 125a and the radial mounting hole 12a provided in the input shaft 12, and the upper end ring portion 12 at both ends.
5a and a connecting rod 125b, which is provided at the center of the input shaft 12 and communicates with the center of the mounting hole 12a at the upper end, and is engaged with the connecting rod 125b at the upper end. The lower end of the second connecting rod 125c is engaged with the connecting shaft 22. Since the other constructions and effects of this embodiment are substantially the same as those of the above-mentioned embodiment shown in FIGS. 1 and 2, similar members are designated by the same reference numerals and the description thereof will be omitted.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a power steering apparatus according to the present invention.

FIG. 2 is a partially cutaway side view of a main part of the power steering apparatus shown in FIG.

FIG. 3 is a partially cutaway side view of an essential part showing a modified example of the connector.

[Explanation of symbols] 11 ... Valve housing, 12 ... Input shaft (first shaft), 1
4 ... Output shaft (second shaft), 14b ... Solid cam, 15 ... Valve rotor, 16 ... Valve sleeve, 16a, 16b, 1
6c ... passage, 21 ... cam follower, 24 ... spring,
25 ... Connecting tool, C ... Power cylinder, C1, C2 ... Oil chamber.

Claims (1)

[Claims] 1. A valve rotor that rotates integrally with a first shaft that is rotatably supported in a valve housing, and a second rotor that is coaxially and relatively rotatably connected to the first shaft by a predetermined amount.
A valve sleeve that rotates integrally with the shaft and is concentrically arranged on the outer periphery of the valve rotor, and a valve sleeve that is provided between the valve sleeve and the valve rotor and that rotates relative to both shafts supplies and discharges oil to and from each oil chamber of the power cylinder. A control valve mechanism for switching the passage, a three-dimensional cam symmetrically formed at one end of the second shaft in the rotation direction, and a three-dimensional cam that is axially movable and integrally rotatable with the first shaft are attached to the three-dimensional cam. A cam follower that moves in the axial direction when the both shafts rotate relative to each other; a spring that is arranged coaxially on the outer periphery of the first shaft on the first shaft side of the valve sleeve and that flexes in the axial direction; A power steering apparatus, comprising: a connector for transmitting a spring force of a spring to the cam follower to press the cam follower toward the solid cam.