JPS5953221A - Hydropneumatic suspender - Google Patents

Abstract

PURPOSE:In a hydropneumatic suspender where the hydraulic chamber of an air spring is conducted to the hydraulic chamber of a hydraulic cylinder, to maintain comfortability stably by controlling an electromagnetic throttle valve in accordance to the variation of load with reference to an intermediate load thereby correcting the spring constant. CONSTITUTION:A front wheel suspender 1 is equipped with a hydraulic cylinder coupled to a lower arm for supporting the wheel 14 on a piston rod 10, where said hydraulic chamber 9 is conducted 4 through a throttle 30 to the hydraulic chamber 5 of an air spring 2 to be partitioned from an air chamber 3 through a diaphragm 4. Here first and second electromagnetic throttle valves 23, 24 are coupled in parallel against the throttle 30. While air springs 2A, 2B are connected in parallel with the air spring 2 through solenoid valves 21, 22. Each throttle valves 23, 24 and solenoid valves 21, 22 is controlled properly by a microcomputer 65 on the basis of comparison between the output from a load sensor 16 for detecting the spring load and the setting level thus to correct the spring constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention adjusts the damping force of the hydraulic cylinder unit according to the magnitude of the load applied by the occupant, etc. ! This invention relates to a hydropneumatic suspension system for a vehicle that provides a stable ride.

In conventional hydraulic suspension systems, for example,
As seen in Publication No. 5, a system has been devised that suppresses the tilt of the car body in response to changes in driving conditions, but it has not been possible to adjust the damping force in response to the load. Not yet. That is, since the damping force and the spring constant, which affect the ride comfort of a vehicle, are set in advance to have characteristics corresponding to the average load, it is not possible to maintain optimal ride comfort regardless of changes in the load.

In particular, in suspension systems using air springs, the damping ratio is set to a constant value, so when the applied load is small, the damping is fast, but when the applied load is large, the damping is too slow and the occupants tend to get sick. In addition, since the spring constant has the characteristic of rising rapidly in response to the deflection of the air spring, when the applied load increases, the riding comfort deteriorates, and when the applied load decreases, the spring constant becomes too small, causing roll rigidity. The disadvantage is that the value decreases too much.

Therefore, the purpose of the present invention is to set the damping force so as to obtain an appropriate ride comfort for a medium load or two levels of high and low loads, and to set the damping force according to an increase or decrease in the load based on this. An object of the present invention is to provide a hydronic suspension system that provides stable ride comfort by correcting the above.

For this reason, the structure of the present invention is such that a diaphragm is installed in the fluid chamber of the hydraulic cylinder attached to the vehicle body.
In a hydropneumatic DRY device in which liquid chambers of an air spring divided into an air core and a liquid chamber are communicated with each other, an electromagnetic throttle valve disposed in the hydraulic cylinder unit; The control circuit includes a spring load sensor, etc. that detects the sprung load, and a control circuit that compares the signal of the load sensor with a signal corresponding to the set cart and controls the electromagnetic throttle valve.

- As shown in FIG.
The cylinder 72 of the hydraulic cylinder unit that supports Contact Vt1 of air spring 2 to liquid chamber 5
'ru. Then, one or more electromagnetic throttle valves 23 are connected in parallel with the throttle 30.

The load is detected by the load sensor 16 from the hydraulic pressure in the throttle valve 38 that connects the cylinders of the left and right hydraulic cylinder units, and this detection signal and a signal corresponding to the set load from the signal generator 20 are sent to the control circuit 27. In comparison, riding comfort is improved by opening and closing the electromagnetic throttle valve 23 to obtain a damping force according to the load. .

To explain the structure of the present invention based on an embodiment, as shown in FIG. 2, the hydropneumatic suspension system 1 includes a hydraulic cylinder unit consisting of a cylinder 7 and a piston 8 fitted into the cylinder 7. . The upper end of the cylinder 7 is supported by a suitable means on the vehicle body, while the piston 8 is connected to a rond 10, and the lower end thereof is connected to the lower arm 13 through a ball joint 28. lower arm 1
3 is supported by the vehicle body with a bin 29 extending in the front-rear direction at its base end, while the tip end is connected to the wheel 1 via a known knuckle.
4 is supported.

The air spring 2 for elastically supporting the piston 8 with respect to the vehicle body is partitioned into a liquid chamber 5 and an air chamber 3 by a diaphragm 4 inside the box. The liquid chamber 9 of the cylinder 7 is communicated with the liquid chamber 5 of the air spring 2 through a passage having a throttle 30.

According to the invention, a normally closed first and second electromagnetic throttle valve 23,24 is connected in parallel with the throttle 3o,
When each of the solenoids 23a and 24a is energized, the spool moves and a throttle passage is inserted and connected in parallel with the valve 30.

Although not directly related to the gist of the present invention, it is preferable that the liquid chamber 5 of each air spring 2A, 2B and the liquid chamber 5 of the air spring 2
Normally closed electromagnetic on-off valves 21 and 22 are inserted and connected to the passage connecting the two, and when each solenoid 21a, 22a is energized, the spool moves, and the air spring 2 is connected to the air spring 2A, 2B. configured.

Although only the suspension system @1 of the left front wheel 14 is shown in FIG. 2, the right front wheel has a similar configuration, and the fluid chambers 9 of both cylinders 7 communicate with each other through a conduit 17 and a throttle 38. This is designed to maintain a balance between the left and right heights and to suppress 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 switching valve 37 is a neutral position port block type, and is normally set to the neutral position by a return spring 39. When the solenoid 37a is energized, the conduit 17 is connected to the pressure accumulator 36, and when the solenoid 37b is energized, the conduit 17 is connected to the pressure accumulator 36, and when the solenoid 37b is energized, Conduits 17 are connected to the liquid reservoirs 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 32 is directly returned to the liquid tank 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 stabilizer 45, which is a rod bent into a U-shape, is connected to the left and right lower arms 13 via a connecting member 41 and a six-pin 42, and the center portion of the stabilizer 45 is supported by the vehicle body with a rubber pusher, etc. This stabilizer +F45 moves to balance the up and down movement of the left and right wheels 14, and also rotates as the vehicle height changes. A rod 43 is connected to the tip of an arm 44 connected to the stabilizer 45, and vertical displacement of the rod 43 as the stabilizer 45 rotates is detected by a vehicle height sensor 12 such as a bouncy meter.

In order to detect the load of the vehicle from the hydraulic pressure in the liquid chamber 9 of each cylinder 7, a load sensor 16 is preferably installed at the throttle 38.

In the embodiment of the present invention, the air spring 2 is connected to the liquid chamber 9 of the cylinder through the throttle 30 for a medium load, and is set in advance so as to obtain the optimum damping force and spring constant. One or both of the electromagnetic throttle valves 23 and 24 are connected in parallel with the throttle 30, and one or both of the air springs 2A and 2B are connected to the air spring 2 based on the signal from the load sensor 16 in response to an increase or decrease in load. is connected to correct the damping force and spring constant, and further operates the electromagnetic directional control valve 37 based on the signal from the vehicle height sensor 12 to maintain the vehicle height at a predetermined height.

Such control is performed by the microcomputer 65, for example. The microcomputer 65 is composed of a microprocessor 66, a memory 67, and an interface 68. A signal corresponding to the FIIM load is sent to the interface 68 by the load sensor 16 from the ADvi converter 26.
The vehicle height is input as a digital signal by the vehicle height sensor 12, and the vehicle height is manually inputted as a digital signal by the AD converter 25.

The ROM of the memory 67 stores in advance a signal so that the vehicle height can be adjusted to any desired height, for example, three levels of high, medium, and low, from the outside. Also, R01' of the memory 67, =
I has a standard hydraulic pressure P that is somewhat larger than the medium load.
A first signal corresponding to F) 1 and a second signal corresponding to F)2, which is somewhat smaller than the medium load, are stored. The first of these. By comparing the second reference hydraulic pressure P+, P2 and the signal from the load sensor 16, each electromagnetic throttle valve 23
．． 24 and electromagnetic on-off valves 21 and 22 are operated.

FIG. 3 shows a flowchart of the program described above. In the figure, p11 to p26 indicate each step of the flowchart. At the same time as the engine is started, the calculation section is set to pll, and the control program is executed once every predetermined time determined by p12. On page 13, the vehicle height can be selected from high, medium, or low using the operating button on the driver's seat depending on the road conditions. At p14, the signal from the vehicle height sensor 12 is continuously read. Then, changes in vehicle height from the vehicle height sensor 12 are integrated over a certain period of time to obtain an average vehicle height.

plG the average vehicle height and the height standard selected in I) 13.
Compare with. If the average vehicle height is higher than the height reference, the solenoid 37b of the electromagnetic directional control valve is energized in step p17, and the working fluid in the fluid chamber 9 of the cylinder 7 is returned to the fluid tank 31 to lower the vehicle height. Then, the process returns to page 14, and the signal from the vehicle height sensor 12 is repeatedly read, and the average vehicle height is compared with the height reference 9- as in the case described above.

If the average vehicle height determined on page 15 is lower than the height standard selected on page 13, 1) the electromagnetic directional control valve 37 is activated in 18;
The solenoid 37a is energized, and pressurized fluid is supplied from the cylinder pressure device 36 to the fluid chamber 9 of each cylinder 7 via the electromagnetic directional control valve 37 to raise the vehicle height. Then, the process returns to p14 and repeatedly reads the signal from the vehicle height sensor 12, calculates the average vehicle height in p15, and compares it with the height reference in p1G.

In addition, if the average vehicle height and the height reference are approximately equal in plG, the solenoid a7a of the electromagnetic directional control valve 37 is
, 37b are both demagnetized, and the vehicle height is maintained at that height.

Then, at p20, the signal of the load lens 16 is soaked, and p
At step 21, the average hydraulic pressure P is determined by integrating over a predetermined period of time. p
At step 22, it is determined whether the average hydraulic pressure P is greater than the first reference hydraulic pressure PI. When the average hydraulic pressure P is higher than the first reference hydraulic pressure P1 (including when it is equal to it), the solenoids 23a and 24a of the electromagnetic on-off valves 23 and 24 are kept demagnetized at p23. At the same time, the solenoid 21a of the electromagnetic on-off valve 21.22.

22a is excited, and the air springs 2A and 2B are connected to the air spring 2 to reduce the spring constant of the air springs.

If the average hydraulic pressure P is lower than the first reference hydraulic pressure P1,
At p24, it is determined whether the average hydraulic pressure P is higher than the second reference hydraulic pressure P2. When the average hydraulic pressure P is higher than (including when equal to) the second reference hydraulic pressure P2, the solenoid 23a of the electromagnetic throttle valve 23 is energized in p25, and the throttle passage of the electromagnetic throttle valve 23 is energized in parallel with the throttle 30. Connect to reduce the damping force. At the same time, the solenoid 21a of the electromagnetic on-off valve 21 is energized, and only the air spring 2A is connected to the air spring 2 to increase the spring constant.

If the average hydraulic pressure P is lower than the second reference hydraulic pressure P2,
Solenoid 23a of each electromagnetic throttle valve 23.24 at p2B,
24a is excited, and each electromagnetic throttle valve 23.
24 throttle passages are connected to further reduce the damping force.

At the same time, the solenoids 21a and 22a of the electromagnetic on-off valve 21 are demagnetized, and only the air spring 2 is used to further increase the spring constant.

According to the present invention, when the load is medium as described above,
The damping force is set to the optimum damping force, and the first criterion is a load larger than a medium load, and for a load larger than this, only the throttle 30 is used, and for a medium load, the throttle 3 is used.
0 is connected to the electromagnetic throttle valve 23 to reduce the damping force, and a load lower than a medium load is used as the second standard.For a load smaller than this, two electromagnetic throttle valves 23 are connected to the throttle 30. Since the damping force is further reduced by connecting the . Further, since roll rigidity commensurate with the applied load can be obtained, stable maneuverability can be obtained.

In the above embodiment, if the hydraulic cylinder unit has a liquid chamber partitioned by pistons at both ends of the cylinder, a throttle 30 and an electromagnetic throttle valve 23, 24 are installed in the passage connecting the liquid chambers at both ends. The upper end liquid chamber of the cylinder and the liquid chamber 5 of the air spring 2 are placed in direct communication with each other.

In addition, the load sensor was designed to detect the hydraulic pressure at the restrictor connecting the cylinders of the left and right hydraulic cylinder units, but measures such as combining a resistance strain gauge between the piston rod and lower arm were also taken. The load may also be detected.

Further, instead of using a plurality of throttle valves, a single variable throttle valve may be used to control the opening degree of the throttle passage.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a hydropneumatic suspension system according to the present invention, FIG. 2 is a configuration diagram of the same device, and FIG. 3 is a flowchart of a program for controlling the same device. 1: Suspension device 2: Air spring 5, 9: Liquid chamber 7: Cylinder 12: Vehicle height sensor 16: Load sensor 23a,
24a, 37a, 37b: Solenoid 23.24
: Electromagnetic throttle valve 3: Liquid tank 32: Hydraulic pump 36: Pressure accumulator 37: 1m direction switching valve 38: Throttle 13- 1st section

Claims (1)

[Claims] A hydropneumatic system in which the liquid chamber of an air spring, which is divided into an air chamber and a liquid chamber by a diaphragm, is communicated with the liquid chamber of the cylinder of the hydraulic cylinder Conit attached to the vehicle body! ! In the four rack installation, an electromagnetic throttle valve disposed in the hydraulic cylinder unit and a load sensor for detecting a sprung barge are compared, and a signal from the load sensor is compared with a signal corresponding to a set load. A hydropneumatic suspension system consisting of a control circuit for controlling a throttle valve.