JPS632803B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber for a vehicle, and more specifically, the damping force can be adjusted to high or low by switching a switching device, and the steering angle can be adjusted when the vehicle travel speed is above a predetermined value. When the control unit detects when the damping force exceeds a predetermined value, it activates the switching device and switches the damping force to a higher one, setting the damping characteristics higher, preventing the vehicle body from sinking when turning, and improving maneuverability. The above describes a hydraulic shock absorber for a vehicle which performs this function even during braking, prevents the front of the vehicle body from sinking, and furthermore maintains a fail-safe function.

Hydraulic shock absorbers used as suspension systems for vehicles moderately suppress unsprung vibrations caused by large bumps in the road surface, prevent resonance on the springs, and prevent rolling during steering operation and pitching during acceleration and deceleration. It is necessary to increase the damping force to some extent to suppress this.

On the other hand, if the damping force is set high, vibrations caused by unevenness in the road surface will be transmitted to the vehicle body, resulting in disadvantages such as deterioration of ride comfort and increase in road noise.

Normally, the damping force of a hydraulic shock absorber is set at a moderate level to satisfy both of these requirements.
It is difficult to sufficiently eliminate both the suppression of rolling and pitching, etc., which require a large stroke of the hydraulic shock absorber, and the suppression of vibrations caused by unevenness in the road surface, which require a small stroke.

In order to improve the above problem, we installed a variable orifice and adjusted the damping force to high or low by changing the orifice.
A hydraulic shock absorber is proposed to obtain a damping force corresponding to the conditions.

The present inventors have developed a system in which the damping force of a hydraulic shock absorber that constitutes a suspension system of a vehicle is adjustable, to effectively suppress rolling and pitching of the vehicle to improve maneuverability. In this situation, the present invention is eliminated in order to fully exhibit the original buffering performance, control the above as necessary, and maintain a fail-safe function.

An object of the present invention is to detect when the steering angle is above a predetermined value and the traveling speed is above a predetermined value, and to switch the hydraulic shock absorber to the one with higher damping force to prevent sinking during low and long driving. In addition to the above, even if a brake operation is detected, the above is performed to prevent the front of the vehicle from sinking or pitching during braking, and the above switching is performed using negative pressure to prevent failures or detection of negative pressure system. To provide a hydraulic shock absorber for a vehicle that maintains a fail-safe function by switching damping force to a higher level in the case of an electrical system failure.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an explanatory circuit diagram of the control method, in which the equipment is shown schematically.

In FIG. 1, a detection section for damping force switching is comprised of a steering wheel 1, a speedometer 2, and a foot brake 3. The steering wheel 1 is configured to emit a detection signal when the left and right steering angle is, for example, 30 degrees, that is, after the position where the steering wheel is steered by 30 degrees to the left or right, and the speedometer 2 is configured to transmit a detection signal when the vehicle speed is, for example, 45 km/hour or more. A detection signal is transmitted.
Separately from these systems, a detection signal is obtained by pressing the brake switch 3a by depressing the foot brake 3. These are the control section 4
For example, the control unit 4 receives detection signals from the steering wheel 1 and the speedometer 2,
Each turns on only when the speedometer 2 detects the above conditions, that is, the steering angle of the steering wheel 1 is turned left or right by more than 30 degrees, and the vehicle speed is more than 45 km/hour.
It includes an AND circuit 5 and a NOR circuit 6 which turns off in response to the ON of the AND circuit 5 and a detection signal of brake operation. These are the solenoid 7a of the electromagnetic switching valve 7.
is sent to NOR by turning on the AND circuit 5 above.
When the circuit 6 is turned off or when the NOR circuit 6 is turned off due to the brake switch 3a being turned on, a signal is transmitted to turn off the normally-on solenoid 7a, for example. In this case, the control unit 4 and the solenoid 7
A lamp 8 is provided in the system 4a of the engine 4 to indicate that the solenoid 7a is turned off, that is, that the hydraulic shock absorber described later has been switched.

9 is the intake path of the carburetor, and the throttle valve 9a
The downstream P _B negative pressure is stored in the storage tank 10 through the throttle 10a, and the inlet of the storage tank 10 is equipped with a check valve 10b for preventing backflow, and 10c indicates that the pressure in the storage tank 10 is at a predetermined level. This is a lamp that displays.

The tank 10 is connected to the switching valve 7 via a pipe line 10d.
The switching valve 7 is, for example, shown as a three-port, two-position switching valve in the illustration, and when the solenoid 7a is in the normally on position, the negative pressure line 10 is connected to the passage 7b.
d and the supply pipe line 11 to the hydraulic shock absorber are connected in communication. On the other hand, the switching valve 7 is provided with an atmosphere opening passage 12, and the passage 12 is connected to the supply pipe line 11 through a passage 7c of the switching valve 7 which moves to the right when the solenoid 7a is turned off, thereby opening the supply pipe line 11 to the atmosphere. The supply pipe line 11 is connected via four branch pipe lines 11a to 11d to each switching actuator (negative pressure actuator) 13 of a hydraulic shock absorber 20 that supports four front, rear, left and right wheels.

As is clear from the figure, each switching operation section 13 includes a pressure chamber 13b partitioned by a diaphragm 13a,
The diaphragm 13a is connected at its upper end to a control rod 21 of the hydraulic shock absorber 20, and is connected to the throttle mechanism 40 via the control rod 21. As will be described later, the throttle mechanism 40 increases the orifice area (area of the communication passage) by upward movement of the control rod 21 to lower the damping force, thereby obtaining soft damping characteristics that function effectively during normal driving. Then, the control rod 21 is moved downward to reduce the orifice area, increase damping force, and obtain hard damping characteristics.

Next, to explain its function systematically, during normal driving, the solenoid 7a is normally on, so the switching valve 7 is moved to the left in the illustrated position, and the negative pressure is applied to the storage tank 10, the pipe 10d, the passage 7b, and the pipe. Road 1
1 into the pressure chamber 13b of the hydraulic shock absorber 20..., which sucks the diaphragm 13a upward with negative pressure, and the control rod 2 connected thereto.
Move 1 up. Therefore, the orifice area of the hydraulic shock absorber 20 is large, and the damping force is set low to obtain soft shock absorbing performance that follows bumps and bumps in the road surface.

On the other hand, when the vehicle speed is above a certain level and the steering angle is above a certain angle, the damping force characteristics of the above-mentioned shock absorber will cause the car body to sink significantly on the inner side of the turn due to centrifugal force, causing a so-called rolling phenomenon, causing the car's attitude to change from left to right. It is tilted to the ground, which is unfavorable for driving safety. Therefore, such conditions are detected by the steering wheel 1 and speedometer 2 as described above, and when both conditions are met, the AND circuit 5 is turned on, this is transmitted via the NOR circuit 6, the solenoid 7a is turned off, and the switching is performed. Switch the valve 7. The switching valve 7 moves to the right, and the pipe line 10
d and 11, and connect the pipe line 11 and the atmosphere opening passage 12 with the passage 7c, that is, the pressure chamber 1
3b... is communicated with the atmosphere. As a result, the negative pressure that keeps the diaphragm 13a moving upward disappears,
The control rod 21 moves downward to reduce the orifice area, which increases the damping force and provides a hard damping characteristic.In other words, the hydraulic shock absorber is tightened to prevent rolling and prevent the vehicle body from sinking when turning. , to ensure maneuverability under these conditions.

This is also the detection signal when braking with brake 3.
It is output from the NOR circuit 6, turns off the solenoid 7a, performs the same operation as above, and prevents the vehicle body from sinking due to inertia during braking.

By the way, in the above, if the electrical system or detection system that operates the solenoid 7a fails, the switching valve 7 turns off the solenoid 7a and connects the pipe line 11 to the atmosphere opening passage 12 through the passage 7c according to the above, The hydraulic shock absorber 20 is maintained at a high damping force side, that is, a hard shock absorbing characteristic, to ensure safe handling. In other words, it exhibits a fail-safe function.

If the negative pressure supply system fails, the pressure in the pipe line 10d becomes atmospheric, and the pressure in the pipe 11 becomes atmospheric, ensuring safe operation and providing a fail-safe function in the same way as described above.

By the way, an example of the hydraulic shock absorber 20 used above is shown in FIGS. 2 and 3, and FIG. 3 is an enlarged view of the damping force variable adjustment section.

The embodiment shows a double-tube type, with an inner/outer tube 22,
23, and inside the inner cylinder 22 there is a piston rod 2.
A piston 25 fixed to the piston 4 is slidably fitted, and the piston rod 24 extends upward from the cylinder.
This is supported on the vehicle body side, and the outer cylinder 23 is supported on the wheel side. The control rod 21 described above is inserted vertically into the vertical passage hole 24a provided in the piston rod 24, and the lower end of the rod 21 protrudes from the lower surface of the piston 25, and is interposed between the spring receiver 26 provided at the lower end and the bottom of the piston. The rod 21 is pressed downward in the axial direction by a spring 27. The left half of FIG. 2 shows a state in which the rod 21 is moved upward by the diaphragm 13a due to the negative pressure operation described above, and the above-mentioned throttle mechanism 40 is moved between the control protrusion 19a of the rod 21 and the passage member 28 when the rod 21 moves upward. The orifice F has a large area, and during the compression stroke, oil in the piston lower chamber B flows to the upper chamber A through passages C, D, and E, orifice F, and passages G, H, and I, thereby obtaining low damping force characteristics. These oil passages C, D,
E-orifice F and passages G, H, and I are communication passage 4
1.

On the other hand, as described above, when the air is opened to the atmosphere, the control rod 21 moves downward due to the spring 27, so the control protrusions 19b and 19a of the rod 21 move downward, and the orifice F is extremely becomes smaller and the damping force increases. This is shown in the right half of Figure 2.

As is clear from the above, according to the present invention, the damping force of the hydraulic shock absorber is switched to the high side when both conditions such as the vehicle speed exceeding a predetermined value and the steering operation angle exceeding a predetermined value are met, and during braking, such as when making a sharp turn. It is possible to suppress tilting of the vehicle posture and forward tilting during braking, improve steering stability, and obtain preferable shock absorbing performance during normal driving. In addition to this, the above is controlled by negative pressure and switched by a solenoid valve, and when the electrical system or negative pressure system fails, it is opened to the atmosphere and the damping force is switched to the higher side. In this case, it is important to ensure safe handling, which is favorable from the point of view of fail-safety, and contributes to improving the safe handling of the vehicle.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory diagram showing an outline of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a hydraulic shock absorber used in the present invention.
FIG. 3 is an enlarged view of the main part. In the drawings, 1 is the steering wheel, 2 is the speedometer, 3 is the brake, 4 is the control unit, 7 is the electromagnetic switching valve, 7a is the solenoid, 9 is the intake path of the carburetor, and 13 is the switching operation unit (negative pressure actuator). ), 13b is a pressure chamber, 20 is a hydraulic shock absorber, 40 is a throttle mechanism,
41 is a communication path.

Claims (1)

[Scope of Claims] 1. A piston is slidably fitted into a cylinder to separate two chambers filled with oil, and a communication path is formed in the piston to communicate the two chambers, and the communication path is formed in the piston. A vehicle hydraulic shock absorber is provided with a throttle mechanism that can adjust the opening degree of a passage, the cylinder is attached to one of the vehicle body or wheels, and the piston is attached to the other of the vehicle body or wheels by a rod. Pressure is introduced into the pressure chamber to drive the throttle mechanism, and when the pressure chamber is opened to the atmosphere, the opening degree of the communication passage is maintained at a predetermined opening degree or less, and the suction negative pressure is introduced into the pressure chamber. a negative pressure actuator that increases the opening degree of the communication passage in accordance with the suction negative pressure when the suction negative pressure is applied; an electromagnetic switching valve that controls the introduced suction negative pressure by energizing a solenoid, opens the pressure chamber to the atmosphere when the solenoid is not energized, and guides the suction negative pressure to the pressure chamber when the solenoid is energized; a controller that controls the energization of the solenoid of the electromagnetic switching valve based on the vehicle speed and steering angle of the vehicle, and stops the energization of the solenoid when the vehicle speed is a predetermined vehicle speed or higher and the steering angle is a predetermined angle or higher; A vehicle hydraulic shock absorber comprising: