JPS61193910A - Active suspension controller - Google Patents

Abstract

PURPOSE:To eliminate an orifice for absorbing the vibration input while to eliminate the power loss by performing the switching control such that the pilot pressure is fed to a changeover valve to reduce the pressure in pressure chamber at the boosting side. CONSTITUTION:The hydraulic cylinder 1 is a fluid pressure cylinder placed between the upper and lower sections of spring where a cylinder tube 1a is fixed rotatably to the wheel side member. The upper end of piston rod 1b is fixed through a resilient member 11 to a chassis side member 2. A direction changeover valve 13 will control the pressure in respective pressure chamber A, B and provided with a proportional solenoid 16. A stroke sensor 26 will detected the under spring stroke against the above spring stroke to provide an electrical signal corresponding with the stroke to a controller 27. A detection signal is fed from the sensor 26 to the controller 27 and compared with a target stroke to provide a control signal CS corresponding with the deviation to the solenoid 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dynamically controlled suspension device capable of suppressing vibration and rocking of a vehicle body by actively controlling the suspension.

[Conventional technology]

As a conventional active suspension device, Japanese Patent Application Laid-open No. 58
- There is something disclosed in Publication No. 79438 (No. 1
conventional example).

As shown in FIG. 2, this device has an actuator 1 consisting of a double-acting hydraulic cylinder mounted on the wheel side member.
The cylinder tube 1a of the actuator 1 is attached, the piston rod 1b of this actuator 1 is attached to the vehicle body side member 2, and the coil spring 3 is installed between the cylinder tube 1a and the vehicle body side member 2. While supporting the vehicle body side member 2, both pressure chambers A and B of the hydraulic cylinder 1 are connected to a hydraulic pressure source 5 via a center bypass type electromagnetic directional switching valve 4. An orifice 6 is connected between both pressure chambers A and B of the actuator 1.

Another conventional example is "Autocar J (H
(Published by Aymarket Publishing Ltd.) (Second Conventional Example).

As shown in FIG. 2(b), the cylinder tube la of the actuator 1, which is a single-acting hydraulic cylinder, is attached to the vehicle body side member 2.
The piston rod 1b is attached to the wheel side member, and the vehicle body side member 2 is supported by a gas spring 7, and this gas spring 7 and the pressure chamber of the hydraulic cylinder 1 are communicated via an orifice 8. There is.

Therefore, the electromagnetic directional control valve 4 of the first conventional example and the second conventional example
is detected by a stroke sensor 9 that detects the relative displacement (stroke) between the unsprung portion and the unsprung portion, and is controlled by the control device 10 so that the stroke fluctuation is reduced.

The control method in this case is as schematically shown in Figure 3.
When steering the steering wheel, depressing the accelerator pedal, depressing the brake pedal, etc., which cause a change in the attitude of the vehicle (block ■), lateral acceleration or longitudinal acceleration occurs in the vehicle body in response (block ■). This causes posture changes such as rolling and pitching in the car body (block ■). When the car body changes its posture in this way, this is detected by the stroke sensor 9 (block Φ), and the detected stroke value and a preset target stroke (zero in a normal state without a change in vehicle attitude), and control the actuator l by controlling the electromagnetic directional control valve 4 according to the deviation (block ■); Thereby, control is performed to reduce changes in the posture of the vehicle body.

[Problem that the invention seeks to solve]

However, in the conventional active suspension system described above, in the first conventional example, when controlling the vehicle attitude, hydraulic oil is also directly supplied to the drain side through the orifice, so the hydraulic oil source is There was a problem in that the power loss for driving was large.

In addition, since both the first conventional example and the second conventional example generate damping force using an orifice with fixed characteristics, the excitation force from under the spring is input to the vehicle body through the orifice, resulting in insufficient improvement in ride comfort. was there.

Therefore, this invention was made by focusing on the above-mentioned conventional problems, and utilizes the increase in pressure in one pressure chamber of the hydraulic cylinder due to vibration input to the vehicle body, and uses this pressure to increase the pressure in the switching valve. The purpose of this invention is to reduce the vibration input transmitted to the vehicle body by switching to reduce the pressure in the side pressure chamber, thereby solving the above problem.

[Means for solving problems]

In order to solve the above problems, the present invention provides a fluid pressure cylinder that is interposed between the sprung mass and the sprung mass of a vehicle and absorbs vibration input from the wheel side to the vehicle body side, and both the upper and lower sides of the fluid pressure cylinder. A switching valve for controlling the pressure in a pressure chamber and a control device for controlling the switching valve, the pressure in both the upper and lower pressure chambers of the fluid pressure cylinder being respectively supplied as pilot pressure to the switching valve, and the switching valve for controlling the switching valve. is characterized in that the pressure is switched to reduce the pressure in the pressure chamber on the pressure increasing side and to increase the pressure in the pressure chamber on the pressure reducing side.

[Effect]

This invention supplies the pressure as pilot pressure to the switching valve when either one of the upper and lower pressure chambers in the fluid pressure cylinder interposed between the sprung mass and the sprung mass of a vehicle is in a pressure-increased state due to vibration input. Then, by switching this switching valve to a direction that reduces the pressure in the pressure chamber on the pressure increasing side, that is, a direction that cancels the pressure, the vibration input is absorbed by the fluid pressure cylinder without using an orifice.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention.

In the figure, I is a hydraulic cylinder as a fluid pressure cylinder interposed between an unsprung part and an unsprung part of a vehicle, and its cylinder tube 1a is rotatably attached to a wheel side member (not shown). At the same time, the upper end of the piston rod tb is attached to the vehicle body side member 2 via an elastic body 11, and a coil spring 3 is interposed between the cylinder tube 1a and the vehicle body side member 2. Here, the cylinder tube 1a is defined into a lower pressure chamber A and a lower pressure chamber B by a piston lc attached to the lower end of a piston rod 1b extending into the cylinder tube 1a.

The elastic body 11 is, for example, a rubber elastic cylinder 11a and a metal disk 11b bonded to the upper and lower surfaces of the elastic cylinder 11a.

11c, and is attached to the vehicle body side member 2 by fitting the peripheral edge of a through hole 2a formed in the vehicle body side member 2 into an annular slit lid formed in the axial center of the elastic cylinder 11a. has been done. Then, the elastic cylinder 1 of this elastic body 11
The small-diameter end 1d of the piston rod lb is fitted into the interior 1a, and is fixed by screwing and tightening a Nand 12 onto a threaded portion le connected upwardly to the small-diameter end 1d of the piston rod lb.

Reference numeral 13 denotes a directional switching valve that controls the pressure in each pressure chamber A, B of the hydraulic cylinder 1, and includes a cylindrical valve housing 14;
A spool 15 that is slidably disposed within the valve housing 14 and a proportional solenoid 1 that controls the movement of the spool 15 between a neutral position and offset positions at both ends thereof.
6, the one-valve housing 14 has input ports 14a and 14b connected to the hydraulic oil supply side of the hydraulic source 17 via a hydraulic piping 18, and input ports 14a and 14b connected to the drain side of the hydraulic source 17 via a hydraulic piping 19. Hydraulic pipes 20 and 21 are connected to the output port 14c and the pressure chambers A and B of the hydraulic cylinder 1, respectively.
input/output boats 14d and 14e connected via;
Opens at the upper end of the spool 15 and branches hydraulic piping 2
2, a pilot boat 14f connected to the hydraulic piping 20 via a Actuator 1
An insertion hole 14h through which the hole 6a is inserted is formed. .

In addition, lands 15aN15c are formed on the spool 15, and the lands 15aN15c face the input boats 14a, 14b and the output port 14c of the valve housing 14.
A pressing spring 24 is interposed between the lower end surface of c and the bottom wall of the valve housing 14, and the spool 15 is moved to each land by this pressing spring 24 and a spring that presses an actuator 16a of a proportional solenoid 16, which will be described later. 15a~
15c is held in a neutral position that closes each boat 14a to 14c of the valve housing 14.

Further, the proportional solenoid 16 includes an actuator 16a that is slidable in the axial direction, an excitation coil 16b that drives the actuator 16a, and a pressing spring 2 that controls the spool 15 via the actuator 16a.
a pressing spring 25 that is in equilibrium with 4 and held in a neutral position;
It is composed of.

Reference numeral 26 denotes a stroke sensor that detects the stroke (displacement amount) of the unsprung portion relative to the sprung portion.
It is composed of an actuator 26b attached to the detector 2.
6a is composed of, for example, a potentiometer, and outputs an electric signal according to the stroke to the control device 27.

The control device 27 is supplied with the detection signal of the stroke sensor 26, compares this with a preset target stroke, calculates a deviation between the two, and outputs a control signal CS corresponding to this to the proportional solenoid 16. That is, when the actual stroke detected by the stroke sensor 26 is shorter than the target stroke, it is determined that the vehicle height at that wheel position is decreasing, and the actuator 16a of the proportional solenoid 16 is adjusted so that the vehicle height becomes the target vehicle height. is lowered by a predetermined stroke from the neutral position in FIG. When the actual stroke detected by the stroke sensor 26 is longer than the target stroke, it is determined that the vehicle height at that wheel position is rising, and the actuator of the proportional solenoid 16 is controlled to match the target stroke. 16a is raised by a predetermined distance from the neutral position, hydraulic oil is supplied to the lower pressure chamber A of the hydraulic cylinder 1 to increase the pressure in this pressure chamber A, and thereby the cylinder tube 1a is raised to change the actual stroke to the target stroke. Control to match.

Next, the operation will be explained. Now, it is assumed that the vehicle is traveling straight at a constant speed on a flat, good road, and there is almost no vibration input to the wheels from the road surface. Assuming that no posture change such as bounce has occurred, in this state, the stroke of the unsprung portion relative to the unsprung portion approximately matches the target stroke, and the control device 27 does not output the control signal CS, and the proportional solenoid 16 is in a non-energized state, and
Since there is no vibration input transmitted from the wheel side to the vehicle body side member 2 via the hydraulic cylinder 1 and the load on the vehicle body side is supported by the coil spring 3, the pressure in the pressure chambers A and B is in a relatively low state. Therefore, the pressure at the pilot boat 14f and 14g positions of the valve housing 14 is low compared to the pressing force of the pressing springs 24 and 25, so that the spool 15 maintains the neutral position shown in FIG. . Therefore, the boats 14a to 14c connected to the hydraulic power source 17 of the valve housing 14 are closed by the lands 15a to 15c. As a result, the pressures in both pressure chambers A and B of the hydraulic cylinder 1 are maintained at the same predetermined value.

In this state, when an excitation force is input to the wheel due to, for example, riding over a convex portion of the road surface, the hydraulic cylinder 1 is pressed upward. At this time, both pressure chambers A and B are in a blocked state, and the piston loft lb is connected to the vehicle body side member 2 via the elastic body 11, so that it is elastic against a relatively small excitation force. The excitation force can be absorbed by the deformation of the body 11, but when the excitation force cannot be absorbed by the deformation of the elastic body 11, the pressure in the lower pressure chamber B of the hydraulic cylinder 1 increases. In this way, when the pressure in the lower pressure chamber B increases, the pressure of the pilot boat 14g exceeds the pressing force of the pressing spring 25, and the spool 15 is displaced from the neutral position to the upper offset position.

Therefore, the input port 14a and the input/output port 14d
The output boat 14c and the input/output boat 140 communicate with each other, and hydraulic oil from the hydraulic source 17 is supplied to the hydraulic cylinder 1.
At the same time, the hydraulic oil in the lower pressure chamber B is discharged to the drain side of the hydraulic power source 17. As a result, the pressure in the lower pressure chamber A of the hydraulic cylinder 1 is increased and the pressure in the lower pressure chamber B is decreased, so that the pressure fluctuations in the pressure chambers A and B caused by the excitation force are offset and input to the wheels and transmitted to the vehicle body. It is possible to reduce the excitation force caused by

Conversely, when the wheel engages with a concave part of the road surface and a vibration input is input that causes the hydraulic cylinder 1 to be positioned downward, the pressure in the lower pressure chamber A of the hydraulic cylinder 1 increases, so that the pressure of the pilot boat 14f increases. The pressure exceeds the pressing force by the pressing spring 24, and the spool 15 is displaced from the neutral position to the downward offset position, and in response, the lower pressure chamber A is connected to the drain side of the hydraulic source 17 and the pressure is reduced. With,
Since the lower pressure chamber B is connected to the hydraulic oil supply side of the hydraulic pressure source 17 and is pressurized, the vibration input that is transmitted to the vehicle body and lowers it is reduced.

In this way, vibration input from the road surface to the wheels can be absorbed, vibration of the vehicle body can be reduced, and ride comfort can be improved.

Also, when the vehicle is running straight, turn the steering wheel (
(not shown) to shift to a right (or left) turning state, for example, the vehicle body will roll, and the vehicle height at the front left wheel and rear left transport position will decrease, and the front right and rear right wheels will The vehicle height at the location will be higher. In this way, when a change in the posture of the vehicle body occurs, this is detected by the stroke sensor 26 at each wheel position, and the detection signal is supplied to the control device 27. A control signal CS for lowering the actuator 16a is applied to the proportional solenoid 16 of the device, and a control signal CS for lowering the actuator 16a is applied to the proportional solenoid 16 of the suspension device at the front right wheel and rear right wheel positions.
A control signal CS to raise the voltage 6a is outputted respectively. Therefore, in the suspension device on the left side of the vehicle, the spool 15 of the directional control valve 13 is displaced from the neutral position to the lower offset position, reducing the pressure in the lower pressure chamber A of the hydraulic cylinder 1, and lowering the pressure in the lower pressure chamber B. , thereby raising the piston rod 1b and raising the left side of the vehicle body. Conversely, in the suspension system on the right side of the vehicle, the spool 15 of the directional control valve 13 is displaced from the neutral position to the upper offset position, increasing the pressure in the lower pressure chamber A of the hydraulic cylinder 1 and increasing the pressure in the lower pressure chamber B. The pressure is lowered and the piston rod lb is lowered, thereby lowering the right side of the vehicle body and exerting an anti-roll effect.

Similarly, when the brake pedal is depressed, causing a so-called nose dive phenomenon on the car body, or when the accelerator pedal is depressed, causing a so-called scuttle phenomenon on the car body,
When the vehicle body pitches, the pressure in the lower pressure chamber A of the hydraulic cylinder 1 of the suspension device on the side where the vehicle height has decreased decreases, and the pressure in the lower pressure chamber B increases, raising the vehicle body and lowering the vehicle height. Hydraulic cylinder 1 of the suspension device on the raised side
The pressure in the lower pressure chamber A increases, the pressure in the lower pressure chamber B decreases, and the vehicle body is lowered to produce an anti-pitch effect. Also, when a vehicle bounces, such as when driving on an undulating road surface, the bounce state (
or rebound state), the pressure in the lower pressure chambers A of the hydraulic cylinders 1 of all suspension devices increases (or decreases), and the pressure in the lower pressure chambers B decreases (or increases) to exert an anti-bounce effect. can do.

In this way, changes in the posture of the vehicle body due to roll, pitch, bounce, etc. can be easily and reliably suppressed by displacing the spool 15 of the directional control valve 13 from the neutral position by the control device 27.

In the above embodiment, a case has been described in which a hydraulic cylinder is used as the fluid pressure cylinder, but the present invention is not limited to this, and it goes without saying that other fluid pressure cylinders such as a pneumatic cylinder can be used.

Further, in the above embodiment, a case was described in which a stroke sensor consisting of a potentiometer was applied as a relative displacement detection means for detecting the relative displacement between the unsprung part and the unsprung part, but the invention is not limited to this. Of course, any relative displacement detection means such as a differential transformer can be applied.

〔Effect of the invention〕

As explained above, according to the present invention, vibration input to the fluid pressure cylinder interposed between the unsprung part and the unsprung part of the vehicle causes either the lower pressure chamber or the lower pressure chamber of the fluid pressure cylinder to When the pressure rises, that pressure is supplied as pilot pressure to the switching valve, and this switching valve is controlled to reduce the pressure in the pressure chamber on the pressure rising side. This eliminates the power loss of the hydraulic oil flowing to the drain through the orifice, making it possible to efficiently control transmission to the vehicle body and control changes in vehicle body posture. Since the switching valve operates using pressure fluctuations in the pressure chamber, there is no need for attached equipment such as a load sensor that detects vibration input and its control circuit, making it possible to simplify the overall configuration and improve responsiveness. Effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
) and (bl are respectively block diagrams of conventional devices, and FIG. 3 is an explanatory diagram for explaining the control method thereof. 1...Hydraulic cylinder (fluid pressure cylinder), 1a
...Cylinder tube, 1b...Piston rod, A...Lower pressure chamber, B...
Lower pressure chamber, 2...Vehicle body side member, 13...
・Directional switching valve, 14...Valve housing, 14a
, 14b... Input port, 14C...
Output port, 14d, 14e... Input/output boat, 14f, 14g... Pilot boat, 15
... Spool, 16 ... Proportional solenoid, 26 ... Stroke sensor, 27 ...
...Controlling device.

Claims (3)

[Claims] (1) A fluid pressure cylinder that is interposed between the sprung mass and the unsprung mass of a vehicle to absorb vibration input from the wheel side to the vehicle body side, and a switching valve that controls the pressure in both the upper and lower pressure chambers of the fluid pressure cylinder. , and a control device for controlling the switching valve, the pressure in both the upper and lower pressure chambers of the fluid pressure cylinder is supplied as pilot pressure to the switching valve, and the switching valve depressurizes the pressure chamber on the pressure increasing side. An active control suspension device characterized in that the pressure chamber on the decompression side is switched to increase the pressure. (2) The switching valve is composed of a spool valve, and the pressure in the upper pressure chamber of the fluid pressure cylinder is supplied to one end surface of the spool, and the pressure in the lower pressure chamber is supplied to the other end surface of the spool as pilot pressure. An actively controlled suspension device according to claim 1, wherein the spool is moved in a direction that reduces the pressure in the pressure chamber. (3) The control device has a relative displacement detection means for detecting relative displacement between the sprung mass and the sprung mass, and suppresses posture changes such as roll, pitch, and bounce of the vehicle body based on the detection signal of the relative displacement detection means. An active control type suspension device according to claim 1, wherein the switching valve is controlled so as to.