JPS5953220A - Hydropneumatic suspender - Google Patents

Abstract

PURPOSE:In a hydropneumatic suspender where the car height can be adjusted through external operation, to maintain comfortability by controlling the number of connection of two air springs by means of the output from an accelerator sensor for detecting the up/down vibration of a lower arm in the suspender thereby correcting the spring constant. CONSTITUTION:A front wheel suspender 1 is equipped with a hydraulic cylinder where a piston rod 10 is coupled to a lower arm for supporting a wheel 14 and its hydraulic chamber 9 is coupled selectively through an electromagnetic direction exchange valve 37 to a liquid pressure source or a liquid tank 31 having a hydraulic pump 32 and an accumulator 36. The car height is regulated through control of said valve 37. Here said hyrdaulic chamber 9 is coupled through a throttle 30 to the hydraulic chamber 5 of an air spring 2 partitioned from an air chamber 3 through a diaphragm 4 while through the throttle 30 and a solenoid valve 21 to the hydraulic chamber 5 of second air spring 2A. Said valve 21 is opened by a microcomputer 65 when the output from an acceleration sensor 15 for detecting the up/down vibration of the lower arm 13 exceeds over predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydropneumatic suspension system for a vehicle that automatically adjusts the vehicle height and the spring constant of an air spring according to road conditions.

In conventional hydraulic suspension systems, for example,
As disclosed in Publication No. 5, a system has been proposed that suppresses the inclination of the vehicle body in response to changes in driving conditions, but it does not adjust the spring constant to suit the road conditions.

In general, the spring constant of a suspension system, which determines the ride comfort of a vehicle, is set to an average characteristic that corresponds to rough or good roads, so it is possible to achieve the optimum ride comfort for both rough and good road conditions. You can't get it.

The purpose of the present invention is to raise the vehicle height and reduce the spring constant on rough roads, while lowering the vehicle height (larger spring constant) on good roads, in order to obtain better ride comfort. The purpose of the present invention is to provide a suspension system.

For this reason, the configuration of the present invention is such that the liquid chamber of the cylinder of the hydraulic cylinder unit attached to the vehicle body is communicated with the liquid chamber of the first air spring, which is divided into an air chamber and a liquid chamber by a diaphragm. In a hydropneumatic suspension system in which the vehicle height is adjusted by externally adjusting the amount of fluid in the fluid chamber of the cylinder, the fluid chambers are connected to each other via the first air spring and an electromagnetic on-off valve. a second air spring arranged on the lower arm of the suspension system, an acceleration sensor for detecting vibration in the vertical direction, and when the signal of the acceleration sensor exceeds a predetermined value in J3 at a predetermined time, It is equipped with an opening control circuit.

FIG. 1 is an overall configuration diagram for clearly explaining the present invention. A signal from the vehicle height sensor 12 is integrated by an arithmetic circuit 52 for a predetermined time determined by a timer 51, and a signal corresponding to the average vehicle height is added to a comparator 57. On the other hand, the signal from the acceleration sensor 15 attached to the left and right lower arms 13, which detects vibrations in the vertical direction, is applied to a filter 53, and only pulse signals exceeding a predetermined level are counted by a timer 54 for a predetermined period of time. is added to the vehicle height selection calculation circuit 55.

In the case of driving on a rough road based on the number of pulses, the arithmetic circuit 5
5, a signal that sets the vehicle height to a high level is applied to the comparator 57. The comparator 57 compares the high level vehicle height HO with the actual average vehicle height, and if the average vehicle height is lower than the high level vehicle height 1''0, the solenoid 37a is energized and the pressure accumulator 3 is activated.
6 is applied to the cylinder of the hydraulic cylinder unit 1- through the electromagnetic directional control valve 37 (see FIG. 2) to raise the vehicle height.

On the other hand, if the actual average vehicle height is higher than the high level vehicle height HO in the comparator 57, the solenoid 37h is energized and the hydraulic fluid in the cylinder 7 is returned to the fluid tank to lower the vehicle height. Such an operation is repeated at predetermined time intervals, and when the actual average vehicle height matches the high level vehicle height 110, the electromagnetic directional control valve 37 is returned to the neutral position and the vehicle height is maintained.

Then, the vehicle height selection calculation circuit 55 selects a high level vehicle height of 110.
When is selected, the solenoid 21a is excited, and the second air spring 2Δ is connected in parallel with the first air spring 2 to reduce the spring constant of the air spring.

On the other hand, when the vehicle is traveling on a good road, the vehicle height selection calculation circuit 55 applies a signal to the comparator 57 to set the vehicle height to a low level. The comparator 57 compares the low level vehicle height O with the actual average vehicle height, and the electromagnetic directional control valve 37 is operated according to this difference, as in the case of driving on a rough road.

Then, the solenoids 21a are each demagnetized, the second air spring 2A is removed from the first air spring 2, and the spring constant of the air spring is increased.

Next, the configuration of the present invention will be explained based on an example. As shown in FIG. 2, a hydropneumatic suspension system 1
The hydraulic cylinder unit includes a cylinder 7 and a piston 8 fitted into the cylinder. The cylinder 7 has its upper end supported by a suitable means on the vehicle body, while a rod 10 is connected to the piston 8, and its lower end is connected to the lower arm 13 with a ball joint 28. The lower arm 13 has a base end supported by the vehicle body with a pin 29 extending in the longitudinal direction, and a distal end side supporting the wheel 14 via a known knuckle.

The first air spring 2 for elastically supporting the piston 8 with respect to the vehicle body has a box whose inside is partitioned into a liquid chamber 5 and an air chamber 3 by a diaphragm 4 .

5- The liquid chamber 9 of the cylinder 7 is connected to the liquid chamber 5 of the first air spring 2 by a passage with a restriction 30;

According to the present invention, the liquid chamber 5 of the second air spring 2A is connected to the liquid chamber 5 of the first air spring 2 via the normally closed electromagnetic on-off valve 21, and when the solenoid 21a is excited, the liquid chamber 5 of the second air spring 2A is connected to the liquid chamber 5 of the first air spring 2. 1. The liquid chambers 5 of the second air springs 2, 2A are configured to communicate with each other.

Although this is not the gist of the present invention, preferably, a normally closed electromagnetic throttle valve 23 is connected in parallel with the throttle 30, and a throttle passage is connected in parallel with the throttle 30 when the solenoid 23a is energized.

Although only the suspension system 1 for the left front wheel 14 is shown in FIG. 2, the construction for the right front wheel is similar, and the fluid chambers 9 of both cylinders 7 are connected to each other by a conduit 17 and a throttle 38. This system maintains a balance between the left and right heights and suppresses the increase in body roll when turning.

The conduit 17 is also selectively connected via an electromagnetic directional valve 37 to a pressure accumulator 36 or to a liquid tank 31 . This electromagnetic directional control valve 37 is of the 6-neutral position bow 1-block type, and is normally placed in the neutral position by a return spring 39, and when the solenoid 37a is energized, the conduit 17 is connected to the pressure accumulator 36, and the solenoid 3
When 7b is excited, the conduits 17 are connected to the liquid tanks 31, respectively.

Pressure fluid is filled into the pressure accumulator 36 from the hydraulic pump 32 via the check valve 34 . When the pressure in the pressure accumulator 36 exceeds a predetermined value, the pressure liquid discharged from the hydraulic pump 12 is directly returned to the liquid volume 31 by the relief valve 33.

Although not shown, for the left and right rear wheels, a conduit 18 connected to the pressure accumulator 36 and a conduit 19 connected to the liquid tank 31 are connected to the cylinders of the hydraulic cylinder unit via electromagnetic directional switching valves similar to the electromagnetic directional switching valve 37. It is designed to be selectively connected to the liquid chamber.

A connecting member 41 and a pin 42 are attached to the left and right lower arms 13.
A stabilizer 45 consisting of a rod bent into a U-shape is connected through the stabilizer 45, and the center portion of the stabilizer 45 is supported by the vehicle body with a rubber bush or the like. This stabilizer 45
serves to balance the vertical vibrations of the left and right wheels 14, and rotates as the vehicle height changes.

A rod 43 is attached to the tip of the arm 44 connected to the stabilizer 45.
are connected, and as the stabilizer 45 rotates, the rod 43
The displacement in the vertical direction is detected by a vehicle height sensor 1J-12 consisting of a potentiometer or the like.

Acceleration pins 15 are installed on the left and right lower arms 13 to detect vibrations in the vertical direction. This acceleration sensor 15 has a spring inside a box body to support a weight so as to be movable in the vertical direction, and electrically detects the displacement of this weight.Since such a sensor is well known, the explanation thereof will be omitted here. do.

The electromagnetic directional switching valve 37 and the N magnetic on-off valve 21 are controlled by a microcomputer 65, for example. The micro combi coater 65 has a microprocessor 66 and a memory 67.
and an interface 68. The vertical vibration of the lower arm 13 is detected by the acceleration sensor 15 attached to the lower arm 13 (J-digit), and is input as a digital signal to the AD converter 25, and the vehicle height is detected by the vehicle height sensor 12, and the The signal is input as a digital signal at the converter 26.

The ROM of the memory 67 stores in advance a reference value for the frequency of amplitude equal to or higher than a predetermined value within a predetermined time period for determining the road surface condition, and also stores a reference value HO for raising the vehicle height according to the road surface condition. , and the reference value LO for lowering are stored.

Then, amplitude changes detected by the acceleration sensor 15 that exceed a predetermined level are counted for a predetermined period of time, and the counted value is compared with a reference value stored in advance in the ROM to set the vehicle height to a high level. or low level, and set each standard I! The vehicle height is corrected to a predetermined level by comparing HO and LO with the actual vehicle height and adjusting the amount of fluid in the cylinders of the hydraulic cylinder units in the front and rear wheel suspension systems. At the same time, according to the vehicle height, the electromagnetic on-off valve 2
1. One or both of the second air springs 2.2A are activated and the spring constant of the air springs is adjusted.

9- Arithmetic processing in the microcomputer is performed according to the flowchart shown in FIG. In the same figure, J3 has a pH of ~1)2
G indicates each step of the flowchart. At the same time as the vehicle starts, the input part is turned to pll. At p12, a detection signal from the acceleration sensor 15 that detects vibrations in the vertical direction under the spring is read. p13, only signals above a certain level are sent,
In p14, the number of inputs for a predetermined period of time is compared with a set value previously stored in the ROM of the memory.

If the number of inputs is more than the specified value, set the vehicle height standard to 1 on page 16.
” 0, and turn on solenoid 2 of electromagnetic on-off valve 21 in p17.
1a is excited to increase the spring constant.

If the number of inputs is less than the specified value or 0, 918
Select the vehicle height reference value LO on page 19, and select the electromagnetic on-off valve 21 on page 19.
The solenoid 21a is demagnetized to reduce the spring constant.

Next, in p20, the detection signal of the vehicle height sensor 12 is read, and in p21, the average vehicle height value H is determined by integrating it at fixed time intervals. I) At step 22, it is determined whether the average vehicle height value H is greater than the previously selected height reference value HO or 1o.

If the average vehicle height value H is lower than the height reference *Ho or LO, the solenoid 37 of the electromagnetic directional control valve 37 is activated in p23.
a is excited, and the pressure fluid in the pressure accumulator 36 is applied to the fluid chamber 9 of each cylinder 7 via the electromagnetic directional control valve 37 to raise the vehicle height. If the average vehicle height value l' When the height is substantially equal to the height reference value HO or LO, the solenoids 378 and 37b of the electromagnetic directional control valve 37 are both demagnetized at p25, and the vehicle height is maintained at that height.

Next, in p26, it is determined whether the vehicle height has been maintained at that height for the specified time, and if it is still within the specified time, the specified time has elapsed, and when the specified time has elapsed, the process returns to p12, and the acceleration sensor 15 and the detection signal of the vehicle height sensor 12,
The same performance Q processing as described above is repeated.

As described above, the present invention calculates the average vehicle height using a vehicle height sensor at predetermined intervals, detects the road condition using an acceleration sensor, selects a high or low vehicle height level, and adjusts the vehicle height based on this selection. This system compares the vehicle height reference value with the average vehicle height value and operates the electromagnetic directional control valve to supply pressure fluid to the cylinders of the hydraulic cylinder unit or return it to the fluid tank to adjust the vehicle height. On rough roads, the vehicle height automatically increases to eliminate obstacles such as obstacles on the road touching the underfloor. Stability can be improved.

At the same time, when driving on rough roads, the electromagnetic on-off valve is opened and the two air springs are activated, reducing the spring constant.
The wheels follow changes in the road surface well, and vibrations from the vehicle body are absorbed. Conversely, when driving on a good road, the electromagnetic on-off valve is closed and one air spring is activated, increasing the spring constant, which helps improve driving stability and maneuverability.

In the above embodiment, if the hydraulic cylinder unit is of a type in which the liquid chambers are partitioned by pistons at both ends of the cylinder, a throttle 30 is disposed in the passage connecting the liquid chambers at both ends, and the upper end of the cylinder is It is assumed that the liquid chamber and the liquid chamber 5 of the first air spring 2 are in direct communication.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a hydropneumatic suspension system according to the present invention, FIG. 2 is a configuration diagram of the same system according to an embodiment of the present invention, and FIG. 3 is software for controlling the system. It is a flow chart explaining. 1: Suspension device 2.2A: 1st. Second air spring 5.9
:Liquid chamber 7:Cylinder 8:Piston 10:Rod
12+11 height sensor 13: Lower arm 14: Wheel 15: Acceleration sensor 21: Electromagnetic on-off valve 21a: Solenoid 30: Throttle 31: Liquid tank 36: Pressure accumulator 37
: Electromagnetic directional control valve 37a, 37b: '/Lz/id 45:, 113- Viser 51.54: Timer 52.55: Actor circuit 53: Filter 57: Comparator patent applicant Isuzu Motors Co., Ltd. agent Patent attorney Toshio Yamamoto 14-

Claims (1)

[Claims] The liquid chamber of the cylinder of the hydraulic cylinder unit attached to the vehicle body is communicated with the liquid chamber of the first air spring, which is divided into an air chamber and a liquid chamber by a diaphragm, and the liquid layer in the liquid chamber of the cylinder is In a hydropneumatic suspension 'IA@' in which the vehicle height is adjusted by adjusting the height from the outside, a second air spring whose liquid chambers are connected to each other via the first air spring and an electromagnetic on-off valve is used. A spring, an acceleration sensor arranged on the lower arm of the suspension 5Aw that detects vertical vibration, and a control circuit that opens the electromagnetic on-off valve when the signal from the acceleration sensor exceeds a predetermined value at a predetermined time. A hydropneumatic suspension system characterized by: