JPH0321391B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering damper device used in manual steering vehicles.

For vehicles with manual steering, a steering damper device is used to absorb the vibrations transmitted from the tires to the steering wheel via the steering link, especially when driving on rough roads, to prevent the steering wheel from wobbling or chattering, and to improve steering stability. used.

Many of these damper devices are hydraulically compressed to generate damping force and absorb vibration by squeezing hydraulic fluid.

However, there is a problem in that the volume of hydraulic oil changes depending on the temperature, and as a result, the damping force characteristics also change, and there is also a desire to adjust the damping force to improve maneuverability.

Various proposals have been made in the past to address these problems, but none have yet been effective due to the complexity of the structure.

The present invention was made to solve the above-mentioned problems, and it maintains the damping force characteristics by compensating for the volume change due to the temperature of the hydraulic oil, and also increases or decreases the damping force depending on the driving conditions such as vehicle speed. An object of the present invention is to provide a steering damper device that can improve safety.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, in the case of a four-wheel vehicle such as an automobile, the device of the present invention is installed, for example, between a tie rod 1 and a front axle 2. As shown in detail in FIG. 2, the device is roughly composed of a damper body 3 and a volume compensation tank (hereinafter referred to as tank) 4.

In the damper main body 3, a piston 7 is slidably housed in a cylinder 6 of a body 5, and oil chambers A and B are defined on both sides of the piston 7. A piston rod 8 connected to the piston 7 is slidably supported via a pair of bearings 9, 9 of the body 5, one end 8A of which is connected to the tie rod 1, and the body 5 is connected to the front axle 2. Ru.

The body 5 includes ports 10A and 10B that communicate the oil chambers A and B to the outside, and ports 10A and 10B that connect the oil chambers A and B to the outside.
A passage 12 that communicates with 10B and a port 11 that communicates the passage 12 with the outside are formed.
First check valves 13A and 13B that allow oil to flow only to the port 11 side are housed in 0A and 10B.

Therefore, when the piston 7 is displaced to the left in the figure and the oil chamber A is contracted, as will be described later, the port 1
If the passage of tank 4 communicating with 0A is closed,
Oil flows into the tank 4 through the first check valve 13A, the passage 12, and the port 11, while the oil led from the tank 4 to the port 10B freely passes through the first check valve 13B and enters the oil chamber. It's starting to fall into B.

Further, the piston rod 8 is provided with a passage 14 that communicates the oil chambers A and B, a part of which is formed in an orifice 15, so that the oil passing through the passage 14 is throttled to provide resistance and generate damping force. It's getting old.

In addition, orifice 1 that communicates these oil chambers A and B
5 may be a damping valve.

The tank 4 has a free piston 17 (of course, a diaphragm may be used) slidably housed inside the body 16, and defines an oil reservoir chamber C and a gas chamber D.

The gas chamber D is filled with inert gas (or air) at a predetermined pressure, and pressurizes the hydraulic oil in the oil reservoir chamber C via the free piston 17.

This oil reservoir chamber C is connected to ports 10A, 10B and port 11 of the damper body 3 through a pair of ports 18A, 18B provided on the free piston 17 side and one port 19 provided on the opposite side, respectively. The ports 18A and 18B are connected to the
Second check valves 2, each of which allows oil to flow only outwardly.
0A and 20B are stored.

Therefore, when the oil chamber A is on the contraction side, the oil entering the oil reservoir chamber C from the port 19 flows into the damper body 3 from the port 10B to the oil chamber B via the second check valve 20B. It's getting old.

A pressure control valve 22 that opens only to the free piston 17 side is provided in a case 21 made of magnetic material at the entrance of the oil reservoir C, that is, between the port 19 and the ports 10A and 10B. An electromagnetic solenoid 23 is housed inside.

When the electromagnetic solenoid 23 is excited, the pressure control valve 22 is attracted to the seat portion according to the excitation force, thereby increasing the initial opening pressure of the valve. The electromagnetic solenoid 23 has a control circuit 25
Based on the signal from the vehicle speed sensor 26, the control circuit 25 increases the excitation force in the higher speed range to increase the resistance force of the fluid by the pressure control valve 22.

Next, the operation will be explained with reference to FIG.

When the wheels travel on a rough road, the vibrations received by the wheels from the road surface are transmitted to the steering link, and the piston 7 of the damper body 3 connected by the piston rod 8 of the tie rod 1, which is a part of the steering link, is also vibrated and displaced. Now, when the piston 7 is displaced, for example, to the left in the figure and the oil chamber A is contracted, the oil corresponding to the piston movement volume in the oil chamber A flows into the oil chamber B through the passage 14 of the piston rod 8. 15 and receives resistance, generating a damping force and absorbing vibrations. At this time, when the pressure in the oil chamber A increases due to the rapid contraction speed and reaches the opening pressure of the pressure control valve 22, the second check valve 20A of the tank 4 closes and most of the oil corresponding to the piston movement volume is removed. Therefore, it passes through the first check valve 13A, the passage 12, the port 11,
Push open the pressure control valve 22 from the port 19 of the tank 4 and enter the oil sump chamber C, the second check valve 20B,
It flows into the oil chamber B from the port 10B of the damper body 3. At this time, a damping force is generated due to resistance by the pressure control valve 22 and absorbs the vibration. When the piston 7 moves to the right, the effect is opposite to that described above. By the way, the opening pressure of the pressure control valve 22 is
When the electromagnetic solenoid 23 is excited, for example in a high vehicle speed range, it is attracted to the seat portion and increases in accordance with the exciting force.

This relationship is shown in FIG. 4. When the vertical axis represents the damping force F and the horizontal axis represents the piston speed V, the throttling resistance E of the orifice 15 increases quadratically with respect to the speed change. The initial load of the pressure control valve 22 is determined by the excitation current I of the electromagnetic solenoid 23 depending on the vehicle speed.
Since the orifice resistance increases sequentially in accordance with the pressure control valve 22, when the orifice resistance reaches the cracking pressure of the pressure control valve 22, the damping force is switched to the damping force due to the resistance of the pressure control valve 22. When the damping force during high-speed driving is increased in this way, the movement of the steering link is suppressed at high speeds, and as a result, the steering wheel becomes heavier, preventing excessive steering and improving high-speed steering. . On the other hand, at low speeds, there is less resistance, so the steering wheel does not become heavy.

In this embodiment, the damping force is increased according to the vehicle speed, but it is also possible to change the damping force according to the load, for example, or manually according to the user's preference. good.

On the other hand, in this device, oil chambers A, B to oil sump chamber C are in a closed circuit system, but even if the oil temperature rises due to the flow of hydraulic oil accompanying the movement of the piston 7 and the working cavity expands, Since the free piston 17 of the tank 4 is pressed and moved by the expansion volume and only compresses the gas chamber D, so-called temperature compensation can be achieved and vibration damping force can be prevented from changing due to temperature. The present invention can be applied not only to automobiles but also to two-wheeled vehicles, and in this case, it will be interposed, for example, between an under bracket and a front fork.

Further, the pressure control valve 22 may be a control valve that adjusts the initial load, or may be a control valve that changes the port area by being driven by an electromagnetic solenoid, for example.

As explained above, according to the present invention, the two oil chambers of the damper body are communicated with each other by a restriction such as an orifice, and the passage that communicates both oil chambers is equipped with a defining means such as a free piston of a volume compensation tank. Since the reservoir chamber is provided, the volume change due to the temperature of the hydraulic oil can be compensated for and the damping force characteristics can be maintained appropriately. Furthermore, since a pressure control valve whose opening pressure is increased or decreased by an electromagnetic solenoid is installed at the entrance of the oil reservoir chamber, the damping force can be increased or decreased according to operating conditions, thereby improving operational safety.

[Brief explanation of the drawing]

FIG. 1 is a schematic external view of an embodiment of the present invention, FIG. 2 is a detailed side sectional view, FIG. 3 is a hydraulic circuit diagram, and FIG. 4 is a graph showing the relationship between damping force and piston speed. 2... Damper body, 4... Volume compensation tank, 6
...Cylinder, 7...Piston, 8...Piston rod, 10A, 10B, 11, 18A, 18
B, 19... Port, 12, 14... Passage, 13
A, 13B...first check valve, 15...orifice, 17...free piston, 20A, 20
B...Second check valve, 22...Pressure control valve,
23...Electromagnetic solenoid.

Claims (1)

[Claims] 1. In a steering damper device that absorbs vibrations transmitted from wheels to a steering wheel, a piston is slidably housed in a cylinder to define oil chambers on both sides of the piston, and these oil chambers are A damper body that communicates with each other through a throttle and has one end of a piston rod connected to the piston connected to the vibration transmission path, and a damper body whose interior is defined by a defining means into a gas chamber and an oil sump chamber. It is equipped with a volume compensation tank provided with a pressure control valve at the inlet of the damper body, and a first check valve is interposed at each inlet of the passage communicating between the two oil chambers of the damper body, and the oil is passed between these check valves. A steering damper device characterized in that a second check valve is installed in each passage connected to the inlet of the oil reservoir and connecting the outlet of the oil reservoir and both oil chambers. 2. In a steering damper device that absorbs vibrations transmitted from the wheels to the steering wheel, a piston is slidably housed in a cylinder, oil chambers are defined on both sides of the piston, and both oil chambers are communicated through a throttle. On the other hand, the damper body has one end of the piston rod connected to the piston connected to the vibration transmission path, and the inside thereof is defined into a gas chamber and an oil sump chamber through a defining means, and an inlet portion of the oil sump chamber. and a volume compensation tank equipped with a pressure control valve whose opening pressure is changed by an electromagnetic solenoid, and a first check valve is interposed at each entrance of the passage communicating between the two oil chambers of the damper body. A steering damper device characterized in that a second check valve is connected between the valves and an inlet of an oil reservoir chamber, and a second check valve is interposed in each passage connecting the outlet of the oil reservoir and the two oil chambers. 3. The steering damper device according to claim 2, wherein the electromagnetic solenoid is configured to increase the opening pressure of the pressure control valve in accordance with an increase in vehicle speed.