JPH02182577A - Rack pinion type power steering device - Google Patents

Abstract

PURPOSE:To satisfy both a resisting feeling produced during neutral operation and a light feeling produced during steering of a steering device by a method wherein a valve mechanism to open and close the communicating hole of each oil pressure chamber is mounted to a piston by which the interior of a power cylinder is divided into a plurality of oil pressure chambers. CONSTITUTION:A power cylinder 1 is formed such that a piston 4 by which the interior of a cylinder body is divided into a plurality of oil pressure chambers 3a and 3b is slidably disposed in a cylinder body 2 and a rack lever 5 is disposed in a state to be mounted to the piston 4. In this case, a pair of valve mechanisms 6 are mounted to the piston 4 to open and close a pair of communicating holes 7 formed in the piston 4 so as to intercommunicate the oil pressure chambers 3a and 3b. Namely, when a difference in an oil pressure between the oil pressure chambers 3a and 3b exceeds a specified value during lateral steering of a steering device, each communicating hole 7 is closed by each valve mechanism 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a power steering device for a vehicle such as an automobile, and in particular has good neutral characteristics, that is, when the steering device is in the neutral state, there is a feeling of responsiveness, and it is easy to steer. This invention relates to a rack and pinion type power steering device that is sometimes nimble.

Conventional technology Conventionally, rack and pinion power steering devices are
In order to reduce the steering force, it was possible to obtain a large steering assist force. Therefore, even when the steering device is in the neutral position, a large steering assist force is applied, which may lead to a feeling of anxiety due to a lack of response. To solve this problem, measures have been taken to increase the torsional rigidity of the torsion bar and increase the steering force when in neutral.

The problem that the invention aims to solve is that increasing the torsional rigidity of the torsion bar is the same as constantly applying mechanical resistance to the steering mechanism, which causes an uncomfortable feeling when steering, and also causes problems during sudden steering. There was a problem that an assist delay occurred.

Therefore, the present invention aims to solve the problems of the conventional rack and pinion type power steering device, namely, the fear of causing a feeling of anxiety due to the lack of a feeling of response. The purpose is to eliminate the problem of assist delay sometimes occurring, to provide an appropriate feeling of response when the steering device is in the neutral position, and to provide lightness when turning.

Means for Solving the Problems The main means of the rack and pinion power steering device of the present invention is a piston that is slidably disposed within a power cylinder and that divides the inside of the power cylinder into two hydraulic chambers. The two hydraulic chambers are provided with a communication hole that communicates with each other, and the communication hole is normally opened and closed when the difference in oil pressure between the two hydraulic chambers exceeds a certain level. The first step is to provide a valve mechanism that

Operation By means of such means, when the difference in oil pressure between the two hydraulic chambers separated by the piston in the power cylinder is smaller than a certain value, that is, when the steering system is in the neutral position, the higher one is activated via the open valve mechanism. A portion of the hydraulic pressure is released to the lower side, reducing the steering assist force and giving the driver an appropriate feeling of response.

On the other hand, when the difference in oil pressure between the two hydraulic chambers separated by the piston in the power cylinder is greater than a certain value, that is, during steering, the valve mechanism is closed and the difference in oil pressure is transferred to the effective surface of the piston. It is possible to increase the steering assist force and give the driver a light steering feeling. Therefore, during sudden steering, the difference in the oil pressures between the two oil pressure chambers is equal to or greater than a certain value, so no delay in assisting due to oil pressure occurs.

Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 5.

FIG. 1 is a longitudinal cross-sectional view of a power cylinder section of an embodiment of a rack and pinion power steering device according to the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, and FIG. FIG. 4 is an enlarged longitudinal sectional view corresponding to FIG. 3 of another embodiment of the valve mechanism, and FIG. 5 is a plan view showing the operating state of the valve mechanism depending on the steering position. It is a diagram.

In FIG. 1, reference numeral 1 denotes a power cylinder main body, which is slidably disposed within a power cylinder 2 and inside the power cylinder 2, and has two hydraulic chambers 3 inside the power cylinder.
It has a piston 4 divided into parts a and 3b, and a rack rod 5 that extends in the axial direction through the power cylinder 2 and is attached to the piston 4. The rack rod 5 has a rack gear at one end thereof, and is gear-coupled with a pinion gear of a steering link mechanism (not shown). 6 is a valve mechanism provided in the piston 4, and the piston 4 has two hydraulic chambers 3a.

3b is provided with a communication hole 7 that communicates with each other, and while the communication hole 7 is normally open, the communication hole 7 is closed when the difference in oil pressure between the two hydraulic chambers 3a and 3b exceeds a certain level. 8.8 are two hydraulic chambers 3a.

3b and a hydraulic control mechanism (not shown).

As shown in FIG. 2, it is desirable to provide a plurality of valve mechanisms 6 for safety reasons.

In FIG. 3, 9 is a communication hole 7 provided in the piston 4.
It is a hemispherical round-headed valve provided at both ends of a valve rod 10 that passes through the valve rod, and is biased and held in an open state by a spring 11 located around the valve rod 10.

FIG. 4 shows another embodiment of the valve mechanism 6, in which a spherical valve 12 is held in a communicating hole 7' by a spring 11' so as to be kept open.

Here, according to the operation diagram in FIG. 5, (a) when the steering device is in neutral, (b) when the steering device is turned to the right, and (c) when the steering device is turned to the left Each operating state of the valve mechanism 6 at the time will be explained. When the steering device is in the neutral state as shown in FIG. Since the force is smaller than a certain value, the valve mechanism 6 remains open, and a portion of the higher hydraulic pressure is released to the lower side through the valve mechanism 6 and the communication hole 7, reducing the steering assist force. To give the driver an appropriate feeling of response. Figure (b
) or when the steering device is turned to the right or left as shown in Figure (C), the difference in oil pressure between the two hydraulic chambers 3a and 3b separated by the piston 4 in the power cylinder 2 exceeds a certain value. , since the force acting on the valve of the valve mechanism 6 exceeds a certain value, the valve of the valve mechanism 6 is pushed to one side, closing the valve mechanism 6 and applying a hydraulic differential pressure to the effective surface of the piston, thereby steering the valve. By increasing the assist force, it is possible to give the driver a light steering feeling. Furthermore, even during sudden steering, since the difference in oil pressure between the two oil pressure chambers 3a and 3b is equal to or greater than a certain value, no assist delay due to oil pressure occurs.

Effects of the Invention As described above, the present invention focuses on the amount of movement of the piston due to the difference in steering angular velocity, and the piston in the power cylinder
The amount of movement of the piston near the neutral position of the steering system can be reduced by simply improving the configuration by providing a valve mechanism that opens the communication hole provided in the piston when the steering system is in the neutral position and closes the communication hole when the steering system is turned. In areas where there is a small amount of piston movement, the pressure receiving area of the piston is reduced and the manual steering share ratio is increased to give the driver an appropriate feeling of response. By increasing the pressure-receiving area and reducing the manual steering share ratio, it is possible to increase the steering assist force and give the driver a light steering feel. Furthermore, even during sudden steering, the pressure-receiving area of the piston is quickly increased, and there is no delay in assisting due to hydraulic pressure.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a power cylinder section of an embodiment of a rack and pinion type power steering device according to the present invention;
Figure 2 is a cross-sectional view taken along line A-A in Figure 1, and Figure 3 is a cross-sectional view of Figure 1.
FIG. 4 is an enlarged longitudinal sectional view of the valve mechanism portion of the piston shown in the figure, and FIG. 4 is an enlarged longitudinal sectional view corresponding to FIG. 3 of another embodiment of the valve mechanism. FIG. 5 is a plan view showing the operating state of the valve mechanism depending on the steering position, in which (a) is a diagram of the operating state of the steering device when it is in neutral, (b) is a diagram of the operating state when the steering device is turned to the right; (c
) is an operating state diagram when steering to the left. ■...Power cylinder body, 2...Power cylinder, 3
a, 3b...Hydraulic chamber, 4...Piston, 5...Rack rod, 6...Valve mechanism, 7.7'...Communication (1 idiot)

Claims (1)

[Claims] 1. A power cylinder 2, a piston 4 that is slidably disposed within the power cylinder 2 and divides the inside of the power cylinder 2 into two hydraulic chambers 3a and 3b, and a piston 4 that is attached to the piston 4. In a rack and pinion type power steering device having a rack rod 5 extending in the axial direction through the power cylinder 2, the piston 4 is provided with a communication hole 7 that communicates with the two hydraulic chambers 3a, 3b, and opens the communication hole 7 and connects the two hydraulic chambers 3.
A rack and pinion type power steering device characterized by being provided with a valve mechanism 6 that closes the communication hole 7 when the difference between the oil pressures a and 3b exceeds a certain level. 2 a valve rod 10 through which the valve mechanism 6 passes through the communication hole 7;
A patent claim characterized in that the valve comprises a hemispherical round head valve 9 provided at both ends of the valve and a spring 11 located around the valve rod 10 and biasing and holding the round head valves 9, 9 in an open state. The rack and pinion type power steering device according to item 1. 3. Claim 1, wherein the valve mechanism 6 comprises a spherical valve 12 located within the communication hole 7', and a spring 11' that biases and holds the spherical valve 12 in an open state. The rack and pinion power steering device described.