JPS5953217A - Hydropneumatic suspension - Google Patents

Abstract

PURPOSE:To make a feeling of comfortable driving maintainable so optimum at all times, by controlling the number of connection to plural pieces of air springs in a way of interlocking with a level-control element, while making a spring constant adjustable in an automated manner, in case of a device capable of level-control for a car selectively in times of running on a pavement and on a rough road. CONSTITUTION:A front wheel suspension 1 is provided with a hydraulic cylinder coupled with a lower arm 4 supporting a wheel 5 through a piston rod 3 and connects a fluid chamber 1a of this hydraulic cylinder selectively to a hydraulic pressure source provided with a hydrauric pump 14 and an accumulator 17 or a fluid tank 13 via solenoid directional control valve (selector) 12. The said control valve 12 is controlled for selection by a level-control select switch 31 via a controller 36. In this case, the said fluid chamber 1a is connected to a fluid chamber 6b of an air spring 6 partitioned apart to an air chamber 6a by a diaphragm 6c via a throttle 9 and also to each fluid chamber 6b of air springs 6A and 6B via a solenoid on-off valve 10. And, the solenoid on-off valve also is controlled for its opening or closing by operation of the level-control select switch 31.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hydrostatic system that lowers the vehicle height and increases the spring constant of the air spring when driving on a good road, while increasing the vehicle height and decreasing the spring constant of the air spring when driving on a rough road. This relates to a pneumatic suspension system.

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, driving conditions, etc. improves the driving performance of the vehicle.

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

However, just as vehicle height has a large effect on driving performance, the spring constant of the air springs has an effect on ride comfort depending on whether the vehicle height is high or low. Generally, when raising the vehicle height, you are driving on rough roads, so lower the spring constant to improve ride comfort, and when lowering the vehicle height, you are driving at high speed, so increase the spring constant to improve maneuverability. It is desirable to improve the

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydropneumatic suspension system in which the spring constant of an air spring is automatically adjusted at the same time as the vehicle height is changed.

Therefore, the configuration of the present invention includes a vehicle height selection switch that specifies the vehicle height, an electromagnetic directional control valve that controls the amount of fluid in the cylinder of the hydraulic cylinder unit I-, and a throttle that restricts the flow of hydraulic fluid into and out of the cylinder. In a hydropneumatic suspension system that increases the vehicle height when driving on rough roads and lowers the vehicle height when driving on good roads, a cylinder of the hydraulic cylinder unit of each wheel is selectively a plurality of air springs that communicate with each other, an electromagnetic on-off valve that selects the number of actuated air springs using the vehicle height selection switch, and a signal from the vehicle height selection switch that operates the electromagnetic on-off valve and the electromagnetic directional control valve. The invention is characterized by comprising a control device that operates.

That is, in the present invention, as shown in FIG. 1, a vehicle height selection switch 31 disposed on the driver's seat is used to set the vehicle height high on rough roads and low on good roads. The signal from the vehicle height sensor 18 is integrated by an integrating circuit 35 for a predetermined period of time to obtain an average vehicle height, and the average vehicle height signal and the specified vehicle height signal from the vehicle height selection switch 31 are combined in a control device 36. compare.

Then, the electromagnetic directional switching valve 12 is operated by the output of the control device 36 to obtain a predetermined vehicle height, and the electromagnetic directional switching valve 10 is operated by the control device 36 based on the designated vehicle height signal of the vehicle height selection switch 31. , which changes the spring constant of the air spring.

Next, the structure of the present invention will be explained based on an embodiment. As shown in FIG. ing. The cylinder 1 has its upper end supported by a suitable means on the vehicle body, while a rod 3 is connected to the piston 1b, and its lower end is connected to a control arm 4 through a ball joint. The control arm 4 has a base end supported by the vehicle body 2 with a pin extending in the longitudinal direction, and a distal end side supports the wheel 5 via a known knuckle.

The air spring 6 for elastically supporting the piston 1b with respect to the vehicle body has a box whose inside is partitioned into a liquid chamber 6b and an air chamber 6a by a diaphragm 6C. A liquid chamber 1a of the cylinder 1 is connected to a liquid chamber 6b of the air spring 6 through a passage having a throttle 9.

According to the present invention, the liquid chamber 6b of the air spring 6 and the air spring 6A
, 6B and the liquid chamber 6b are inserted and connected, and the air springs 6 and 68 are normally connected to each other. When the solenoid 10a is energized, the air spring 6
From air spring 6A.

When the solenoid 6B is cut off and the solenoid 10b is energized, the air springs 6A and 6B are connected to the air spring 6.

Although only the suspension system for the left front wheel 5 is shown in Figure W42, the right front wheel has a similar configuration, and the liquid chambers 1a of both cylinders 1 are communicated with each other through a conduit 27 and a throttle 11, and the left and right front wheels are connected to each other. This system maintains a balanced height and suppresses the increase in body roll when turning.

5- Said conduit 27 is also adapted to be selectively connected via an electromagnetic directional valve 12 to a pressure accumulator 17 or to a liquid tank 13; The electromagnetic directional control valve 12 is a boat block type with a neutral position, and is normally set in the neutral position by a return spring.
When the solenoid 12b is energized, the conduit 27 is connected to the pressure accumulator 17.
When the solenoid 12a is energized, the conduit 27 connects to the liquid tank 1.
3, respectively.

Pressure fluid is filled into the pressure accumulator 17 from the hydraulic pump 14 via the check valve 16 . When the pressure in the pressure accumulator 17 exceeds a predetermined value, the pressure liquid discharged from the hydraulic pump 14 is directly returned to the liquid tank 13 by 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 29 connected to the liquid tank 13 are connected to the cylinders of the hydraulic cylinder unit via electromagnetic directional control valves similar to the electromagnetic directional control valve 12. It is designed to be selectively connected to the liquid chamber.

A star riser 21 consisting of a rod 6- bent into a U-shape is connected to the left and right control arms 4 via a connecting member 22 and a pin, and the center portion of the riser 21 is supported by a rubber bush or the like on the vehicle body. 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 attached to the tip of N20 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 Figure 1,
The vehicle height selection switch 31 changes the vehicle height between H (high) and N (medium) by rotating the knob 31a.

It can be switched to three levels: L (low).

The control device 36 is configured with a microcomputer, for example, and selects specified vehicle height values HH, H from the vehicle height selection switch 31.
In response to the digital signal corresponding to N*HL, an air spring of 6.6A is applied to the electromagnetic switching valve 10.

6B switching control signal is sent.

The integration circuit 35 integrates the vehicle height detection signal from the vehicle height sensor 18 at predetermined time intervals according to instructions from the microcomputer to determine the average vehicle height ah.

The microcomputer compares the specified vehicle height value of the vehicle height selection switch 31 with the average vehicle height value, and selects the N magnetic direction switching valve 1.
2 to bring the average vehicle height closer to the designated vehicle height.

FIG. 3 is a flowchart of the control program described above.

In the figure, 1)11 to p23 indicate each step of the flowchart. First, when driving on a normal road, the driver sets the knob 31a of the vehicle height selection switch 31 to the N position in p12, and in p15 the solenoid of the electromagnetic switching valve 10 is activated based on the signal from the vehicle height selection switch 31. 10a and 10b remain demagnetized, and the air spring 6°6A is activated. Further, the vehicle height value HN designated by the vehicle height selection switch 31 is stored in the memory of the microcomputer. Next, the vehicle height detection signal from the vehicle height sensor 18 is read at IJ17, and this is integrated for a predetermined time at step 18 to obtain the average vehicle height.

At p19, the average vehicle height value is compared with the designated vehicle height value HN previously stored in the memory. If the average vehicle height value is higher than the designated vehicle height value HN, the solenoid 12a of the electromagnetic directional control valve 12 is energized in p20, and the hydraulic fluid is transferred from the cylinder 1 to the liquid tank 1.
Return to 3 to lower the vehicle height. Then, return to page 19 and repeatedly execute the program to bring the vehicle height closer to the specified vehicle height value HN. If the average vehicle height value 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 to supply pressurized fluid to the cylinder 1 to raise the vehicle height. Then, return to page 19 and repeatedly execute the program to bring the vehicle height closer to the specified vehicle height value HN. If the average vehicle height value becomes almost equal to the designated vehicle height value HN in p19, the solenoid 12a of the electromagnetic directional control valve 12 is activated in p21.
, 12b are demagnetized and the vehicle height is maintained. Then, in p23, it is determined whether or not the demagnetized state of the solenoids 12a and 12b has elapsed for a predetermined period of time. If the predetermined time has not elapsed, the time continues, and when the predetermined time elapses, the process returns to ρ17 and the above-described program is repeatedly executed.

When driving on a rough road, the driver switches the vehicle height selection switch 31 to H based on the pH. At p14, the solenoid 10b of the electromagnetic switching valve 10 is energized based on the signal from the vehicle height selection 9-switch 31, and all of the air springs 6, 6A, and 6B are activated to reduce the spring constant. Further, the vehicle height value HH specified by the vehicle height selection switch 31 is stored in the memory. Next, in p17, the vehicle height detection signal from the vehicle height sensor 18 is read, and in p18, this is integrated for a predetermined period of time to obtain the average vehicle height.

At p19, the average vehicle height value is compared with the designated vehicle height value HH previously stored in the memory. The average vehicle height is the designated vehicle height fiI
If it is higher than HH, the electromagnetic directional control valve 12 is activated at p20.
The solenoid 12a is energized, and the hydraulic fluid is returned from the cylinder 1 to the fluid tank 13 to raise the vehicle height. Thereafter, the vehicle height is brought closer to the designated vehicle height value HH in the same manner as in the above case.

Next, on a good road suitable for high-speed driving, the driver switches the vehicle height selection switch 31 to OFF at p13. At p16, the solenoid 10a of the electromagnetic switching valve 10 is energized, and only the air spring 6 is activated to increase the spring constant. Further, the designated vehicle height value 10-1-IL of the vehicle height selection switch 31 is stored in the memory. Next, at p17, the vehicle height detection signal from the vehicle height sensor 18 is read, and this is sent to p17.
The average vehicle height value is determined by integrating for a predetermined time using lB.

At p19, the average vehicle height value is compared with the designated vehicle height value HL previously stored in the memory. Average vehicle height is designated vehicle height HL
If the temperature is higher than
Return to 3 to lower the vehicle height. Thereafter, the vehicle height is brought closer to the designated vehicle height value 1-IL in the same manner as in the above case.

Since the present invention is configured as described above, when driving on a good road at high speed, the vehicle height can be lowered and the spring constant can be increased to improve maneuverability, and when driving on a rough road, the vehicle height can be lowered. The excellent effect of increasing the height, reducing the spring constant, and effectively using the wheel stroke to improve ride comfort can be obtained.

In the above-described embodiment, if the hydraulic cylinder unit is of a type in which the liquid chamber is partitioned by screws 1 to 1 at both ends of the cylinder, a throttle 9 is provided in the passage connecting the liquid chambers at both ends. The upper end liquid chamber of the cylinder and the liquid chamber 6b of the air spring 6 are directly connected.

In addition, in the above-mentioned embodiment, three air springs are arranged in each cylinder, but as shown in FIG. With only spring 6 in operation, the electromagnetic on-off valve 10A is operated on rough roads.
Alternatively, the air spring 6.68 may be activated by opening the air spring 6.

Furthermore, in the above-mentioned embodiment, the vehicle height can be switched to three stages, but it can be changed to two stages, high and low, depending on the conditions of good and bad roads. It is also possible to activate only the air spring 6 at the road and the air springs 6 and 6A at the PA 28, respectively.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the overall configuration of a hydropneumatic suspension system according to the present invention, FIG. 2 is a configuration diagram showing an embodiment of the same device, and FIG. 3 is a block diagram illustrating an embodiment of the same device. Flow chart, FIG. 4 is a block diagram showing a partially modified embodiment of the present invention. 1 Niji cylinder 1a: Liquid chamber 4: Control arm
5: Wheel 6.6A, 6B: Air spring 10.10A:
Electromagnetic switching valve 10a, 10b, 12a, 12b: Solenoid 12: Electromagnetic directional switching valve 13: Liquid tank 14: Hydraulic pump 18: Vehicle height sensor 31: Vehicle height selection switch 3
5: Integral circuit 36: Control device patent applicant: Isuri Motor Co., Ltd. agent, patent attorney Toshio Yamamoto 13-

Claims (1)

[Claims] It is equipped with a vehicle height selection switch to specify the vehicle height, an electromagnetic directional control valve to set the fluid level in the cylinder of the hydraulic cylinder unit to Mall, and a throttle to restrict the flow of hydraulic fluid into and out of the cylinder. In a hydropneumatic suspension system that raises the vehicle height and lowers the vehicle height when driving on good roads, a plurality of air springs selectively communicate with the hydraulic cylinder units and cylinders of each wheel. and a control device that operates the electromagnetic on-off valve and the electromagnetic directional control valve in response to a signal from the vehicle height selection switch. A hydropneumatic suspension system characterized by: