JPH02141367A - Reaction force mechanism for power steering device - Google Patents

Abstract

PURPOSE:To provide stable reaction force characteristics by a method wherein, in a device in which reaction force pistons are caused to front on end parts on both sides of a transmission pin mounted on a stub shaft, a contact part between the transmission pin and the reaction force pin is formed such that its length is increases in the radial direction of the sub shaft. CONSTITUTION:When a stub shaft 1 is steered for rotation, through rotation of a transmission shaft 12 through which the sub shaft 1 is coupled to a torsion bar 3, reaction force pistons 14 and 15 positioned on a diagonal line are moved against the forces of springs 18 and 19. Fluid in reaction force chambers 7 and 8 is extruded through discharge ports 26 and 27, and flows to a drain chamber 30 through a variably throttle 31 the opening of which is regulated according to a car speed. In the above formed reaction force mechanism, the both ends of the transmission pin 12 are forced to approach the ceiling parts of the reaction force chambers 7 and 8, and the length of a contact part between the transmission pin 12 and the reaction force piston 14 and 15 is increased radially of the stub shaft 1. This constitution enables execution of centering of the transmission pin without using a special means.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a reaction force mechanism for a power steering device that performs power assist using the operating force of a power cylinder and generates a steering reaction force using fluid pressure.

(Prior Art) The conventional power steering device shown in Fig. 4.5 connects a stub shirt 1 connected to a steering wheel and a gear shaft 2 connected to the output side, which is the power cylinder side, by torsion. They are connected via a bar 3. Also, the stub shaft l and the control valve V that controls the flow path to the power cylinder.

They are linked via a planetary gear mechanism G.

Therefore, at the initial stage when the stub shirt 1 is rotated by turning the steering wheel, the gear shaft 2 does not rotate due to the deflection resistance.

Therefore, the stub shaft 1 and the gear shaft 2 rotate relative to each other while twisting the torsion bar 3.

When the stub shaft 1 rotates in this way, the rotational force is transmitted to the control valve V via the planetary gear mechanism G.
This control valve V is switched. Then, the power cylinder operates according to the switching direction of the control valve (2) to steer the wheels in the desired direction.

The power steering device as described above is provided with one reaction force mechanism, and this reaction force mechanism is as shown in FIG.

That is, reaction force chambers 6, 7.8, and 9 are formed on the gear shaft 2 side, and a positioning protrusion 10.11 is formed at the boundary between these reaction force chambers 6, 7.8, and 9. ing.

The stub shaft 1 is provided with a transmission pin 12, which passes through the stub shaft 1 and the torsion bar 3 in the diametrical direction thereof. Both ends of the transmission pin 12 thus constructed face the reaction force chamber side, and when the stub shaft 1 is kept in neutral, both ends of the transmission pin 12 face the protrusion 10.11.
I try to face them in a straight line.

Further, reaction force pistons 13 to 1B are provided in each of the reaction force chambers 6 to 9, and springs 17 to 20 are applied to each of these pistons. Under the action of the springs 17-20, the reaction pistons 13-16 normally come into contact with the projections 10.11. When the reaction pistons 13 to 16 are in contact with the protrusion 10.11 in this way, the transmission pin 1 along with the stub shaft
2 also maintains a neutral position.

Each of the reaction force chambers 6 to 9 as described above has oil passage holes 21 to 2.
4 and a discharge boat 25 to 2 days. The discharge ports 25 to 28 communicate with a drain chamber 30 via a passage 29, and this passage 29 is provided with a variable throttle 31.

The variable throttle 31 is configured to adjust its opening depending on the speed of the vehicle. In other words, the opening degree of the variable diaphragm 31 increases during low-speed driving, and decreases during high-speed driving.

Now, if the stub shaft 1 is rotated together with the steering wheel and the transmission pin 12 is turned clockwise in FIG. 5, the reaction piston 14.15 positioned diagonally moves against the spring 18.19. do. When the pistons 14 and 15 move in this way, the fluid in the reaction chambers 7 and 8 is pushed out from the discharge ports 2B and 27, and the variable throttle 3
1 into the drain chamber 30.

At this time, if the vehicle is running at a low speed, the opening degree of the variable throttle 31 is large, so that the throttle resistance is almost eliminated. To do this, you can turn the steering wheel lightly.

On the other hand, when driving at medium and high speeds, the opening degree of the variable throttle 31 becomes smaller, and the throttle resistance increases accordingly, so the pressure inside the reaction force chamber 7.8 increases; This pressure acts as a reaction force against the rotational force of the stub shaft l.

Since this stub shirt (1) is connected to the steering wheel, the pressure in the reaction force chamber is ultimately transmitted to the steering wheel as a steering reaction force. Note that the reaction piston 14.15 that moves with the rotation of the transmission pin 12 is the reaction piston 13.1 located on the opposite side.
Even if pressure acts on the reaction chamber 6.6, if the pressure is changed, the reaction force chamber 6.
Even if pressure fluid flows into the reaction piston 13.
18 comes into contact with the protrusion 1O111, and its movement is restricted. Since the movement of the reaction force pistons 13 and 16 is regulated in this way, it does not have the same effect on the steering reaction force described in "2".

(Problems to be Solved by the Invention) As described above, the conventional reaction force mechanism requires the protrusion 10.11 to maintain the transmission pin I2 in the neutral position.

Moreover, if the dimensions of the protrusions 10, 11 are even slightly off, there is a problem that accurate reaction force cannot be obtained.

For example, as shown in FIG. 6, when the dimensions of the protrusion 10.11 have an error of δl and 62 on the left and right sides,
If you turn the steering wheel to the left and turn stub shaft 1 to the left, the transmission pin! 2 also turns to the left.

At this time, pressure fluid flows into each reaction chamber 6 to 9, so that the force of the reaction piston 14, 15 acts on the transmission pin 12.

However, as mentioned above, there are errors δ1 and δ2, so the acting force of the reaction pistons 14 and ]5 is.

Acting in the direction of assisting the movement of the transmission pin 12,
For that purpose 1. If there is an error as described above, no reaction force will be generated.

Furthermore, when the steering wheel is turned in the opposite direction to the above, a normal reaction force will be obtained.

Therefore, according to the conventional reaction force mechanism, the protrusion 10.1
It is necessary to improve the machining accuracy of No. 1, and if the accuracy is incorrect, there is an inconvenience that the reaction force characteristics will differ depending on the steering direction of the steering wheel.

An object of the present invention is to provide a mechanism that can stabilize reaction force characteristics without particularly increasing processing accuracy.

(Seven steps to solve the problem) The first and second inventions are configured to control the flow path to the power cylinder by switching the control valve according to the rotation of the stub shaft, and the stub shaft has a diameter A transmission pin penetrating in the direction is provided, both ends of this transmission pin face a reaction force chamber, and reaction force pistons are brought into contact with both sides of this transmission pin, so that the pressure of the reaction force chamber is applied to the reaction force piston. This method is based on a reaction force mechanism of a power steering device that obtains the desired steering reaction force.

And, the first invention is based on the above-mentioned reaction force mechanism, and
It is characterized by having both ends of the transmission pin close to the ceiling of the reaction force chamber, and by elongating the contact portion between the transmission pin and the reaction piston in the diametrical direction of the stub shaft.

In addition, the second invention also makes the above-mentioned reaction force mechanism as simple as possible, and has a set of reaction force chambers located point-symmetrically with respect to the center of the stub shaft, and each set of reaction force chambers is arranged in the same position in the power cylinder. It is characterized by the point where it communicates with the cylinder chamber.

(Operation of the present invention) Since the first invention is configured as described above, when the transmission pin rotates, a pressing force of 1 anti-capiston acts on the transmission pin. At this time, the reaction torque generated on the transmission pin differs depending on the pressing force of the reaction pistons facing each other. In other words, the reaction torque due to the reaction piston acting on the tip of the transmission pin is greater than the reaction torque due to the reaction piston acting on the inside of the tip.

In this way, the reaction torque generated on the transmission pin is different due to the pressing force of the reaction pistons facing each other, and this difference in reaction torque becomes a reaction force against the steering force.

In addition, in the second invention, the reaction force chambers located at points symmetrical positions are communicated with the same cylinder chamber of the power cylinder, so that
The load pressure of the power cylinder comes to act on the reaction force chamber. Therefore, if the power cylinder is in the middle position, the pressures on the left and right sides of the reaction force chamber will automatically become equal. In other words, if the power cylinder is centered, this transmission pin will also be automatically centered.

(Embodiment of the present invention) FIG. 1.2 shows a first embodiment, and the configuration for finally transmitting the input from the stub shaft 1 to the gear shaft 2 is completely the same as the conventional one. Therefore, the details of the configuration similar to the conventional one will be omitted, and the same reference numerals as in FIG. 4.5 will be used to describe these components.

In this first embodiment, the transmission pin 12 faces the reaction force chambers 6 to 9, which is exactly the same as in the conventional case, but the tip of the transmission pin is made sufficiently long in the diametrical direction of the stub shirt (l), and This differs from the conventional one in that the conventional protrusion 10.11 is omitted.

Now, if the control valve (1) is held at the neutral position, the pressures in each reaction force chamber 6 to 9 will be equal, so the transmission pin 12
is also automatically kept in a neutral position.

If the stub shaft 1 is rotated one turn, for example to the right, by turning the steering wheel, the state shown in FIG. 2 will be obtained. In this state, the distance #J11 from the point of action P1 of the reaction force piston 13 on the transmission pin 12 to the center of the stub shaft 1.

The distance glfL 2 from the point of application P2 of the other reaction force piston 14 to the center is fi2>i+. In other words, the reaction torque generated by the reaction piston 13 and 1
The reaction torque generated by the anticapiston 14 is
Although the magnitudes are different, the difference in the varus torque ultimately becomes the steering reaction force.

Therefore, the reaction torque acting on the transmission bottle 12 is T=((also 2-sentence, )XF)X2.

As described above, according to the reaction force a structure of the first embodiment, the transmission bottle 1 can be
2 can be automatically centered, and the transmission bin 1 can be automatically centered.
It is possible to generate a steering reaction force according to the direction of rotation of No. 2.

In the second embodiment shown in FIG. 3, the conventional protrusion 10.0 is omitted in each reaction force chamber 6-9.

Further, among the L product number reaction chambers, reaction chambers 6 and 9, which are located point-symmetrically to each other, communicate with a cylinder chamber 33 on the left side of the power cylinder C via a passage 32. The passage 32 communicates with the tank T via a variable throttle 34.

11 (The opening degree changes depending on the speed.

Furthermore, the other reaction force chambers 7 and 8 located at point-symmetrical positions are connected to two passages 3.
5 to the right cylinder chamber 3B, and this passage 35 also has a passageway 35 whose opening degree changes according to the vehicle speed.
■ A variable aperture 37 is provided.

Therefore, if the power cylinder C is in the neutral position, the pressures in the reaction force chambers 6 to 9 will all be equal, and the transmission pin 12 will also be automatically centered. And if power cylinder C operates.

The load pressure acts on a set of reaction force chambers located at point-symmetrical positions. However, the pressure inside the reaction force chamber at this time is 1 passage 32
Alternatively, it changes depending on the opening degree of the variable diaphragm 34 or 37 provided at 35.

(Effects of the Present Invention) The reaction force mechanism of the present invention does not require a protrusion within one reaction force chamber, thereby eliminating the conventional problem of having to increase the machining accuracy.

[Brief explanation of the drawing]

Drawings 1.2 show the first embodiment of this invention,
Figure 1 is a sectional view of the main part with the transmission pin centered, Figure 2 is a sectional view of the main part with the transmission pin rotated, and Figure 3 shows the second embodiment. 4 to 6 show the reaction force mechanism of a conventional power steering device. FIG. 4 is a sectional view of the main part of the power steering device, and FIG. FIG. 6 is a cross-sectional view of the main part of the reaction force mechanism, showing an example of a case where a dimensional error occurs in the reaction force mechanism. l...Stub shaft, 2...Gear shaft, C.
...Power cylinder, 6-9...Reaction force chamber, 13-18
...Reaction force piston. Fire 1 Chart 2

Claims (2)

[Claims] (1) The control valve is switched according to the rotation of the stub shaft to control the flow path to the power cylinder, and the stub shaft is provided with a transmission pin that penetrates in the diametrical direction, and both ends of the transmission pin are A reaction force of a power steering device that faces the force chamber and contacts both sides of this transmission pin, and applies the pressure of the reaction force chamber to the reaction piston to obtain the desired steering reaction force. A reaction force mechanism for a power steering device, characterized in that both ends of the transmission pin are located close to the ceiling portion of the reaction force chamber, and the contact portion between the transmission pin and the reaction piston is lengthened in the diametrical direction of the stub shaft. . (2) The control valve is switched according to the rotation of the stub shaft to control the flow path to the power cylinder, and the stub shaft is provided with a transmission pin that penetrates in the diametrical direction, and both ends of the transmission pin are A reaction force of a power steering device that faces the force chamber and contacts both sides of this transmission pin, and applies the pressure of the reaction force chamber to the reaction piston to obtain the desired steering reaction force. In the mechanism, there is a set of reaction force chambers located point-symmetrically with respect to the center of the stub shaft, and each set of reaction force chambers is connected to the same cylinder chamber of the power cylinder to reduce the reaction force of the power steering device. mechanism.