JPH0462885B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention lowers the vehicle height and increases the damping force of the hydraulic cylinder unit when driving on a good road, while increasing the vehicle height and increasing the damping force of the hydraulic cylinder unit when driving on a rough road. This invention relates to a hydroneumatic suspension system designed to reduce damping force.

[Prior Art] It is well known that vehicle height has a large effect on the driving performance of a vehicle. Therefore, maintaining the vehicle height in a state most suitable for road conditions and driving improves the driving performance of the vehicle.

Therefore, in the past, the vehicle height selection device installed in the hydroneumatic suspension system was operated by the driver after getting out of the vehicle, and the frequency of the approach of the vertically movable member of the suspension system to the vehicle body was A system has been proposed that detects the road condition from the amplitude and automatically raises the vehicle height when driving on rough roads, and automatically lowers the vehicle height when driving on good roads.

However, just as the vehicle height has a large effect on driving performance, the damping force of the hydraulic cylinder unit affects ride comfort when the vehicle height is high and low.
Generally, the vehicle height is raised when driving on rough roads, so the damping force is reduced to improve ride comfort.
The vehicle height is lowered when driving at high speeds, so
It is desirable to increase the damping force to improve maneuverability.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the object of the present invention is to provide a hydraulic system in which the damping force of the hydraulic cylinder unit is automatically adjusted to be suitable for the vehicle height at the same time as the vehicle height is changed. The object of the present invention is to provide a pneumatic suspension system.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention is such that the oil chamber of at least one air spring, in which the air chamber and the oil chamber are separated by a diaphragm, is connected to the oil chamber of the suspension cylinder. Restrictions and electromagnetic switching valves that selectively open and close the passages are inserted and connected to a plurality of passages that communicate with the oil chamber of each air spring and the oil chamber of the suspension cylinder. An electromagnetic directional control valve is inserted and connected to the passage connecting the room, and the output of the control device is based on the signal from the manual vehicle height setting device and the signal detected by the vehicle height sensor installed in the suspension system.
The electromagnetic directional control valve is driven to adjust the amount of oil in the oil chamber of the suspension cylinder, and the output of the control device based on the signal from the vehicle height setting device drives the electromagnetic control valve to correspond to the set vehicle height. This increases the number of throttles that communicate the oil chamber of the air spring with the oil chamber of the suspension cylinder.

[Function] According to the present invention, when the vehicle height setting device sets a vehicle height suitable for road conditions, the control device outputs an output based on a signal from the vehicle height setting device and a signal from a vehicle height sensor disposed in the suspension system. The electromagnetic directional valve is driven by
The amount of oil in the suspension cylinder is adjusted. At the same time, the electromagnetic switching valve is driven by the output of the control device based on the signal from the vehicle height setting device, and the amount of restriction of the passage communicating with the air spring and the suspension cylinder is adjusted to be appropriate for the vehicle height.

[Embodiments of the Invention] As shown in FIG. 1, the present invention uses a vehicle height setting device 31 placed in the driver's seat to raise the vehicle height on rough roads.
On good roads, set the vehicle height low. The signal from the vehicle height sensor 18 is integrated for a predetermined period of time by the integrating circuit 35 to obtain the average vehicle height, and the average vehicle height signal and the designated vehicle height signal from the vehicle height setter 31 are sent to the control device 36.
Compare in. The electromagnetic directional switching valve 12 is driven by the output of the control device 36 to obtain a predetermined vehicle height, and the electromagnetic directional switching valve 10 is driven by the output of the control device 36 based on the designated vehicle height signal from the vehicle height setting device 31. Change the damping force of the hydraulic cylinder unit.

Next, the structure of the present invention will be explained based on an embodiment. As shown in FIG.
The hydraulic cylinder unit includes a piston 1b fitted into the hydraulic cylinder unit. The suspension cylinder 1 has its upper end supported on the vehicle body by suitable means, while the lower end of a rod 3 connected to the piston 1b is connected to a control arm 4 by a ball joint. The control arm 4 has its base end supported by the vehicle body 2 by a pin extending in the front-rear direction, while its distal end supports the wheel 5 via a known knuckle.

An air spring 6 for elastically supporting the piston 1b with respect to the vehicle body connects the inside of the box with a diaphragm 6c.
It is partitioned into an oil chamber 6b and an air chamber 6a. The oil chamber 1a of the suspension cylinder 1 is connected to the oil chamber 6b of the air spring 6 through a passage having a throttle 9.

According to the present invention, the apertures 9A, 9 are arranged in parallel with the aperture 9.
B is connected by an electromagnetic switching valve 10. Normally,
The aperture 9 and the aperture 9A are connected in parallel to each other. In the electromagnetic switching valve 10, when the solenoid 10a is energized, the apertures 9A and 9B are cut off, and when the solenoid 10b is energized, the apertures 9A and 9B are cut off.
is connected.

Although only the suspension system for the left front wheel 5 is shown in FIG. 2, the construction for the right front wheel is similar, and the oil chambers 1a of both suspension cylinders 1 are communicated with each other through a conduit 27 and a throttle 11. , maintains a balance between the left and right heights and suppresses vehicle body roll when turning.

The conduit 27 is connected to the pressure accumulator 1 by the electromagnetic directional valve 12.
7 or oil tank 13. The electromagnetic directional control valve 12 is a neutral position port block type, and is normally set to the neutral position by a return spring.
When the solenoid 1b is energized, the conduit 27 is connected to the pressure accumulator 17, and when the solenoid 12a is energized, the conduit 27 is connected to the pressure accumulator 17.
7 are connected to the oil tank 13, respectively.

The pressure accumulator 17 is filled with pressure oil from the hydraulic pump 14 via the check valve 16. When the pressure in the pressure accumulator 17 exceeds a predetermined value, the pressure oil discharged from the hydraulic pump 14 is returned to the oil tank 13 via the relief valve 15.

Although not shown, for the left and right rear wheels, a conduit 28 connected to the pressure accumulator 17 and a conduit 2 connected to the oil tank 13
9 is selectively connected to the oil chamber of the suspension cylinder of the hydraulic cylinder unit by an electromagnetic directional valve similar to the electromagnetic directional valve 12.

A stabilizer 21 consisting of a rod bent into a U-shape is connected to the left and right control arms 4 via a connecting member 22 and a pin. The center portion of the stabilizer 21 is supported by the vehicle body by a rubber bushing or the like. The stabilizer 21 functions to balance the vertical vibrations of the left and right wheels 5, and rotates as the vehicle height changes. A rod 19 is connected to the tip of the arm 20 connected to the stabilizer 21,
The vertical displacement of the rod 19 due to the rotation of the stabilizer 21 is detected by a vehicle height sensor 18 comprising a potentiometer or the like.

Next, the operation of the device of the present invention will be explained. In FIG. 1, the vehicle height setting device 31 adjusts the vehicle height to H (high), N (medium), and L (low) by rotating a knob 31a.
It can be switched to three stages.

The control device 36 is composed of, for example, a microcomputer, and receives the specified vehicle height value from the vehicle height setting device 31.
Receiving digital signals corresponding to H _H , H _N , and H _L ,
A switching control signal for the throttles 9A and 9B is sent to the electromagnetic switching valve 10.

The integration circuit 35 integrates the vehicle height detection signal from the vehicle height sensor 18 at predetermined time intervals according to a command from a microcomputer to obtain an average vehicle height value h.
The microcomputer compares the specified vehicle height value from the vehicle height setting device 31 with the average vehicle height value h, and sends a control signal to the electromagnetic directional control valve 12 to bring the average vehicle height value h closer to the set vehicle height value.

FIG. 3 is a flowchart of the control program described above. In the figure, p11 to p23 indicate each step of the flowchart. First, when driving on normal roads,
At p12, the driver sets the vehicle height setting device 31 to position N,
At p15, based on the signal from the vehicle height setting device 31, the solenoids 10a and 10b of the electromagnetic switching valve 10 are kept demagnetized, the throttles 9 and 9A are connected, and the specified vehicle height value H _N of the vehicle height setting device 31 is set to the micro level. Store in computer memory. Next, read the vehicle height detection signal from the vehicle height sensor 18 in p17, and read the vehicle height detection signal from the vehicle height sensor 18 in p18.
The vehicle height detection signal is integrated over a predetermined period of time to obtain an average vehicle height value h.

At p19, the average vehicle height value h is compared with the specified vehicle height value _HN previously stored in the memory. If the average vehicle height value h is higher than the designated vehicle height value _HN , the solenoid 12a of the electromagnetic directional control valve 12 is energized in p20, the hydraulic oil is returned from the suspension cylinder 1 to the oil tank 13, the vehicle height is lowered, and the process proceeds to p19. Go back and run the program repeatedly,
Bring the vehicle height closer to the specified vehicle height value _HN .

If the average vehicle height value h is lower than the specified vehicle height value _HN in p19, the solenoid 12b of the electromagnetic directional control valve 12 is energized in p22, pressure oil is supplied to the suspension cylinder 1 to raise the vehicle height, and the process returns to p19. Return and repeat the program to bring the vehicle height closer to the specified vehicle height _HN .

If the average vehicle height value h becomes approximately equal to the specified vehicle height value _HN at p19, the solenoids 12a and 12b of the electromagnetic directional control valve 12 are demagnetized at p21 to maintain the vehicle height. Next, in p23, it is determined whether or not each solenoid 12a, 12b of the electromagnetic directional control valve 12 has been demagnetized for a predetermined period of time. If the predetermined time has not elapsed, wait for the time to elapse, and when the predetermined time has elapsed, return to p17 and repeat the above-mentioned program.

When driving on a rough road, the driver switches the vehicle height setting device 31 to position H at p11. At p14, the solenoid 10b of the electromagnetic switching valve 10 is energized based on the signal from the vehicle height setting device 31, the throttles 9, 9A, and 9B are connected to reduce the damping force, and the vehicle height setting device 3
Store the designated vehicle height value H _H of 1 in the memory. Thereafter, the vehicle height is brought closer to the designated vehicle height value H _H in the same manner as in the above case.

If you are driving on a good road suitable for high speed driving, p13
The driver then switches the vehicle height setting device 31 to position L. At p16, the solenoid 10a of the electromagnetic switching valve 10 is energized, the damping force is increased by using only the throttle 9, and the designated vehicle height value H _L of the vehicle height setting device 31 is stored in the memory. Thereafter, the vehicle height is brought closer to the designated vehicle height value H _L in the same manner as in the above case.

In addition, in the above-mentioned embodiment, a variable throttle valve driven by a servo motor, for example, can be used instead of the throttle and the electromagnetic on-off valve.

If the hydraulic cylinder unit is of a type in which the oil chambers are partitioned by pistons at both ends of the suspended cylinder, a restriction is provided in the passage connecting the oil chambers at both ends, and the oil chamber at the upper end of the suspended cylinder and the oil chamber of the air spring are separated. shall be directly connected.

As shown in FIG. 4, a plurality of air springs are provided,
Air springs may be selectively connected depending on road conditions.

In the above-described embodiment, the vehicle height is switched to three levels, but it may be switched to two levels, high and low, depending on the conditions of good and bad roads.

[Effects of the Invention] As described above, the present invention communicates the oil chamber of at least one air spring, in which the air chamber and the oil chamber are separated by a diaphragm, to the oil chamber of the suspension cylinder. A throttle and an electromagnetic directional control valve for selectively opening and closing the passages are inserted and connected to a plurality of passages connecting the hydraulic pressure source and the oil chamber of the suspension cylinder. is inserted and connected, and the output of the control device based on the signal from the manual vehicle height setting device and the signal detected by the vehicle height sensor installed in the suspension system drives the electromagnetic directional control valve to open the oil chamber of the suspension cylinder. The output of the control device based on the signal from the vehicle height setting device drives the electromagnetic directional control valve, and the oil volume in the air spring oil chamber and the suspension cylinder is adjusted according to the set vehicle height. Since the number of apertures communicating with the chambers is increased, the following functions and effects can be obtained.

According to the present invention, when a vehicle height suitable for road conditions is set using a vehicle height setting device, an electromagnetic direction is set by an output of a control device based on a signal from the vehicle height setting device and a signal from a vehicle height sensor disposed in a suspension system. The switching valve is driven,
The amount of oil in the suspension cylinder is adjusted. At the same time, an electromagnetic switching valve is driven by the output of the control device based on the signal from the vehicle height setting device, and the amount of restriction of the passage that communicates with the air spring and the suspension cylinder, in other words, the damping force of the suspension system, is adjusted to suit the vehicle height. be done.

Therefore, when driving on rough roads and setting the vehicle height high, the throttle (area of passage) that communicates the air spring with the suspension cylinder automatically widens, reducing the damping force of the suspension system and making the wheel stroke more effective. This effectively absorbs vibrations caused by road input, improving ride comfort.

When driving on good roads and setting the vehicle height low, the throttle (area of the passage) that communicates the air spring with the suspension cylinder automatically becomes narrower, increasing the damping force of the suspension system and improving maneuverability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the overall configuration of a hydroneumatic suspension system according to the present invention, and FIG.
FIG. 3 is a block diagram showing an embodiment of the same device, FIG. 3 is a flowchart for controlling the same device by a microcomputer, and FIG. 4 is a block diagram showing a partially modified embodiment of the present invention. 1... Suspension cylinder, 1a... Oil chamber, 4... Control arm, 5... Wheel, 9, 9A, 9B
... Throttle, 10, 10A ... Solenoid switching valve, 10
a, 10b, 12a, 12b...Solenoid, 1
2...Solenoid directional control valve, 13...Oil tank, 14...
Hydraulic pump, 18...Vehicle height sensor, 31...Vehicle height setter, 35...Integrator circuit, 36...Control device.

Claims (1)

[Claims] 1. A plurality of passages that communicate the oil chamber of at least one air spring whose air chamber and oil chamber are separated by a diaphragm to the oil chamber of the suspension cylinder, and connect the oil chamber of each air spring and the oil chamber of the suspension cylinder. A throttle and an electromagnetic switching valve that selectively opens and closes the passage are inserted and connected, and an electromagnetic directional switching valve is inserted and connected to the passage that connects the hydraulic pressure source and the oil chamber of the suspension cylinder, and a manual vehicle height setting device is installed. The output of the control device based on the signal and the signal detected by the vehicle height sensor installed in the suspension system drives the electromagnetic directional control valve to adjust the amount of oil in the oil chamber of the suspension cylinder, and adjusts the amount of oil in the vehicle height setting device. The feature is that the output of the control device based on the signal drives the electromagnetic switching valve and increases the number of throttles that communicate the oil chamber of the air spring and the oil chamber of the suspension cylinder in accordance with the set vehicle height. A hydroneumatic suspension system.