JPH0525683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydroneumatic suspension system for a vehicle that prevents the rearward tilting of the vehicle body or the lifting of the front portion of the vehicle body during acceleration.

[Prior Art] Vehicles equipped with conventional hydroneumatic suspension systems consisting of hydraulic shock absorbers and air springs are equipped with a mechanism to adjust the inclination of the vehicle body while the vehicle is running; Since there is no special means to prevent rearward tilting, the rearward tilting of the vehicle body during sudden acceleration causes the vehicle body to sway back and forth, resulting in a lack of running stability and a very uncomfortable ride. Compared to vehicles equipped with conventional hydraulic suspension systems, occupants tended to get sick more easily.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to suppress the rearward tilt of the vehicle body during acceleration, which is noticeable in vehicles equipped with a hydroneumatic suspension system, and to improve ride comfort. An object of the present invention is to provide a hydroneumatic suspension system for a vehicle.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention connects the oil chamber of the hydraulic shock absorber of each wheel to the oil chamber of the air spring partitioned by a diaphragm through an electromagnetic variable throttle valve. The oil chamber of each hydraulic shock absorber can be selectively communicated with the hydraulic power source and the oil tank via an electromagnetic directional control valve.
Equipped with an electronic control device that controls an electromagnetic directional control valve and an electromagnetic variable throttle valve based on signals from an acceleration detector and an engine rotation speed sensor, which determine longitudinal acceleration from changes in the vehicle speed sensor signal, so that the acceleration while the vehicle is moving forward is maintained at a predetermined level. When the value is greater than the value, each electromagnetic directional control valve is switched to connect the oil chamber of the front wheel hydraulic shock absorber to the oil tank and the oil chamber of the rear wheel hydraulic shock absorber to the hydraulic power source, and the lower the engine speed, the lower the engine speed. This throttles each electromagnetic variable throttle valve.

[Effect] The rearward tilt of the vehicle body is noticeable during sudden acceleration from low speed driving, so when accelerating from low speed driving (acceleration from low engine speed), each electromagnetic variable throttle valve is sufficiently throttled and the hydraulic shock absorber is The damping force of the front wheel is increased, and the electromagnetic directional control valves of the front and rear wheel suspension systems are switched in opposite directions based on the signal from the acceleration detector to shorten the front wheel hydraulic shock absorber and extend the rear wheel hydraulic shock absorber. Prevents backward leaning.

To deal with acceleration when the vehicle is running at high speeds, the throttle amount of the electromagnetic variable throttle valve is reduced to reduce the damping force of the hydraulic shock absorber, and the electromagnetic directional switching valves of the front and rear wheel suspension systems are switched in the same way as when the vehicle is running at low speeds. This results in
It suppresses the backward tilt of the vehicle body and provides a soft ride comfort as a hydroneumatic suspension system.

[Embodiments of the Invention] FIG. 1 is an overall configuration diagram for clearly demonstrating the present invention. The front wheel suspension system 1 has a piston 8 fitted inside a cylinder 7 forming a hydraulic shock absorber, and a rod 6 of the piston 8 is connected to a lower arm 2 supporting a front wheel 10.
2, and the cylinder 7 is fixed to the vehicle body side. An air spring 2 is provided to elastically hold the piston 8 by the oil pressure in the oil chamber 9 of the cylinder 7. The air spring 2 is partitioned by a diaphragm 4 into an air chamber 3 (actually filled with nitrogen gas, etc.) and an oil chamber 5, and the oil chamber 5 is connected to the oil chamber of the cylinder 7 via an electromagnetic variable throttle valve 12. 9
connected to.

A vehicle speed sensor 15 consisting of an electromagnetic pick-up type rotation speed sensor is provided at the output shaft end of the transmission, and an acceleration detector 4 is detected based on temporal changes in the signal of the vehicle speed sensor 15.
6 calculates the acceleration of the vehicle and applies it to the control device 24. An electromagnetic pickup type engine speed sensor 48 is provided on the flywheel of the engine, and an acceleration operation state detector 4 based on the signal of the engine speed sensor 48 (intake negative pressure or the amount of operation of the accelerator pedal may be used)
5 is applied to the control device 24. A vehicle height sensor 16 is disposed on the stabilizer 40 of the front wheel suspension system 1, and a signal from the vehicle height sensor 16 is applied to the control device 24.

The control device 24 sends an output signal to the electromagnetic variable throttle valve 12 when the vehicle is in an acceleration operation state and the longitudinal acceleration is above a predetermined value. At the same time, the vehicle height sensor 16
Compare the signal corresponding to the reference height with the signal corresponding to the reference height,
When the vehicle height at the front of the vehicle body is higher than the reference height, the electromagnetic directional switching valve 27 is driven to connect the oil chamber 9 to the oil tank and shorten the front wheel hydraulic shock absorber. At the same time, the electromagnetic directional switching valve 37 (Fig. 2) of the rear wheel suspension system 21, which is similar to the electromagnetic directional switching valve 27 of the front wheel suspension system 1, is driven to connect the oil chamber to the pressure accumulator 36, thereby providing a hydraulic buffer for the rear wheel. Extend the container and prevent the vehicle from tilting backwards.

When the acceleration operation is finished and the vehicle speed becomes constant, the output of the control device 24 based on the signal from the vehicle height sensor 16 and the signal corresponding to the reference height drives the electromagnetic directional control valves 27 and 37 to maintain a predetermined vehicle height. maintain.

Next, the structure of the present invention will be explained based on an embodiment. As shown in FIG. The upper end of the cylinder 7 is supported by a suitable means on the vehicle body, while the lower end of the rod 6 connected to the piston 8 is connected to the lower arm 22.
are connected by a ball joint. The lower arm 22 has its base end supported by the vehicle body by a pin extending in the longitudinal direction, and its distal end connected to the front wheel via a known knuckle.
0 is supported.

The air spring 2 for elastically supporting the piston 8 with respect to the vehicle body has a container whose interior is partitioned into an oil chamber 5 and an air chamber 3 by a diaphragm 4 . The oil chamber 9 of the cylinder 7 is communicated with the oil chamber 5 of the air spring 2 via an electromagnetic variable throttle valve 12 that can change the amount of throttle, and the passage is throttled when the solenoid 12a is energized.

The suspension systems 1 for the left front wheel 10 and the right front wheel 10 have exactly the same configuration, and the oil chambers 9 of the cylinders 7 of both are communicated with each other by a conduit 17 and a throttle 38, and the conduit 17 is connected through an electromagnetic directional control valve 27. It is selectively connected to the pressure accumulator 36 or the oil tank 31. The electromagnetic directional control valve 27 is a neutral position port block type, and is normally set to the neutral position by a return spring 35, and when the solenoid 27a is energized, the conduit 1
7 is connected to the pressure accumulator 36, and when the solenoid 27b is energized, the conduit 17 is connected to the oil tank 31, respectively.

The pressure accumulator 36 is filled with pressure oil from the hydraulic pump 32 via the check valve 34. When the oil pressure in the pressure accumulator 36 exceeds a predetermined value, the pressure oil discharged from the hydraulic pump 32 is directly returned to the oil tank 31 by the relief valve 33.

Regarding the left and right rear wheel suspension systems 21, the pressure accumulator 3
6 and a conduit 19 connected to the oil tank 31.
is selectively connected to the cylinder 7 of the rear wheel suspension 21 via an electromagnetic directional valve 37 and a conduit 17.

A stabilizer 40 consisting of a rod bent into a U-shape is connected to the lower arm 22 of the left and right front wheel suspension system 1 via a connecting member 41 and a pin 42, and the center portion of the stabilizer 40 is supported by the vehicle body by a bearing. The stabilizer 40 functions to balance the vertical vibrations of the left and right wheels, and rotates as the vehicle height changes. A rod 28 is connected to the tip of an arm 29 connected to the stabilizer 40, and changes in the vertical direction of the rod 28 as the stabilizer 40 rotates are converted into voltage by a vehicle height sensor 16 comprising a potentiometer or the like. A similar vehicle height sensor 16 is also attached to the rear wheel suspension system 21.

As shown in FIG. 3, the crankshaft of the engine 54 is connected to the input shaft of a transmission 56 via a clutch, and is opposed to a gear-shaped rotating body 57 made of a magnetic material coupled to an output shaft 58. The vehicle speed sensor 15 is constructed by arranging a pick-up type rotation speed sensor. The engine rotation speed sensor 48 is arranged opposite to the crankshaft of the engine 54.

An amount of air corresponding to the opening degree of the throttle valve 51 disposed in the throttle chamber 52 of the intake pipe 50 is supplied to the engine 54 from the air cleaner 49 to each cylinder from each branch of the intake manifold 53. There is. The intake negative pressure sensor 14 partitions the inside of the box 70 into a negative pressure chamber and an atmospheric chamber by a diaphragm 71, connects the negative pressure chamber to the throttle chamber 52, and has a spring 7 inside the negative pressure chamber.
3, a rod 72 connected to the diaphragm 71 is displaced to a position where the spring 73 and the negative pressure are balanced, and the displacement of the rod 72 is detected as a change in electrical resistance.

As shown in FIGS. 4 and 5, the electromagnetic variable throttle valve 12
The valve body 78 is fitted inside the housing 77,
An oil chamber 79 connected to the oil chamber 5 of the air spring 2 and an oil chamber 76 connected to the oil chamber 9 of the thin lidar 7 are partitioned, and the valve body 7
8 passages 63 with a small cross-sectional area and passages 63a with a large cross-sectional area are arranged at intervals in the circumferential direction, and a valve plate 61 that can selectively close the passages 63 and 63a is provided at the end of the rod 62. Constructed by combining.

As shown in FIG. 6, the valve plate 61 is provided with protrusions 64a for closing the passage 63a at intervals in the circumferential direction, and protrusions 64 for closing the passage 63 are provided on the protrusions 64a. provided between. By rotating the rod 62 by a predetermined angle using an electromagnetic actuator or a servo motor 80, one or both of the passages 63 and 63a are closed to change the fluid resistance.

As shown in FIGS. 1 to 3, the electromagnetic variable throttle valve 12
The electromagnetic directional control valves 27 and 37 are controlled by an electronic control device consisting of a microcomputer 65, for example. The microcomputer 65 is composed of a microprocessor 66, a memory 67, and an interface 68. The interface 68 receives the digital signal detected by the vehicle speed sensor 15 and the digital signal detected by the engine speed sensor 48, and also receives the vehicle height of the front and rear parts of the vehicle body detected by the vehicle height sensor 16, and the intake negative Pressure sensor 1
The negative pressure in the intake pipe detected by 4 is input as a digital signal to AD converters 26 and 39, respectively.

Acceleration is determined from temporal changes in the signal from the vehicle speed sensor 15, and if the acceleration is greater than a standard value, the electromagnetic variable throttle valve 12 is driven to increase the damping force of the hydraulic shock absorber to suppress changes in vehicle height. When the engine speed is higher than a predetermined value, the vehicle height obtained from the vehicle height sensor 16 of the front wheel suspension system 1 is compared with a height reference value at predetermined intervals. When the vehicle height of the front wheels is higher than the height reference value, the solenoid 27b of the electromagnetic directional control valve 27 of the front wheel suspension system 1 is energized, the pressure oil in the oil chamber 9 of the front wheel suspension system 1 is returned to the oil tank 31, and The solenoid 37a of the electromagnetic directional control valve 37 of the rear wheel suspension system 21 is energized, and the oil chamber 9 of the rear wheel suspension system 21 is activated.
When the heights of the front part of the vehicle body and the rear part of the vehicle body reach the standard heights, the solenoids 27b and 37a are demagnetized.

A flowchart of the above-mentioned control program is shown in FIG. In the figure, p11 to p25 indicate each step of the flowchart. At the same time as the engine is started, the calculation part is set to p11, and at p12, signals from the vehicle speed sensor 15 are sequentially read, and acceleration α is calculated from changes in vehicle speed within a predetermined time. At p13, it is determined whether the acceleration α is larger than the reference value. If the acceleration α is smaller than the reference value, return to p12 and repeat the same program.

If acceleration α is larger than the reference value in p13,
In p14, the engine speed is read from the engine speed sensor 14, and in p15, the solenoid 12a of the electromagnetic variable throttle valve 12 of the front and rear wheel suspension systems 1, 21 is energized by the amount of operation corresponding to the magnitude of the engine speed, and the Increase the damping force of the shock absorber.

In p16, the vehicle speed from the vehicle speed sensor 15 is positive (forward)
Determine whether or not. If the vehicle speed is positive, the solenoid 27b of the electromagnetic directional control valve 27 and the solenoid 37a of the electromagnetic directional control valve 37 are energized at p17 to shorten the front wheel hydraulic shock absorber and extend the rear wheel hydraulic shock absorber. The vehicle height H of the front wheels is read in p18, and it is determined in p19 whether the vehicle height H of the front wheels is greater than the height reference value.

If the vehicle height H of the front wheel is larger than the height reference value in p19, return to p17, and continue with solenoid 27b,
37a is excited. If the vehicle height H of the front wheels becomes approximately equal to the height reference value in p19, the solenoid 27b of the electromagnetic directional control valve 27 and the solenoid 37a of the electromagnetic directional control valve 37 are demagnetized in p20, and the process proceeds to p21.

If the vehicle speed is negative in p16, the solenoid 27a of the electromagnetic directional control valve 27 and the electromagnetic directional control valve 37 are connected in p22.
The solenoid 37b is energized, the front wheel hydraulic shock absorber is extended, and the rear wheel hydraulic shock absorber is shortened.

The vehicle height H of the front wheels is read in p23, and it is determined in p24 whether the vehicle height H of the front wheels is smaller than the height reference value. If the vehicle height H of the front wheels is smaller than the height reference value, return to p22 and continue to adjust the solenoids 27a and 37.
Excite b. If the vehicle height H of the front wheel becomes almost equal to the height reference value in p24, the solenoid 27a of the electromagnetic directional control valve 27 and the electromagnetic directional control valve 37
The solenoid 37b is demagnetized and the process ends with p21.

In the above-mentioned embodiment, the engine speed sensor detects that the vehicle is in an acceleration operation state from an increase in engine speed, but instead of the engine speed sensor, an intake negative pressure sensor is used to detect the throttle. Similar effects can be obtained even if the accelerator sensor detects that the vehicle is in an accelerating state because the negative pressure in the chamber becomes close to atmospheric pressure or from a change in the amount of operation of the accelerator pedal.

[Effects of the Invention] As described above, the present invention communicates the oil chamber of the hydraulic shock absorber of each wheel with the oil chamber of the air spring partitioned off by the diaphragm through the electromagnetic variable throttle valve, so that the oil chamber of each hydraulic shock absorber is communicated with the oil chamber of the air spring partitioned by the diaphragm. The chamber can be selectively communicated with a hydraulic power source and an oil tank via an electromagnetic directional control valve, and the electromagnetic directional control valve and electromagnetic control valve are connected to each other based on signals from an acceleration detector and an engine speed sensor, which determine longitudinal acceleration from changes in the vehicle speed sensor signal. Equipped with an electronic control device that controls the variable throttle valve,
When the acceleration while the vehicle is moving forward is greater than a predetermined value, each electromagnetic directional control valve is switched to connect the oil chamber of the front wheel hydraulic shock absorber to the oil tank and the oil chamber of the rear wheel hydraulic shock absorber to the hydraulic power source, respectively. In addition, the lower the engine speed, the more each electromagnetic variable throttle valve is throttled, resulting in the following effects.

(a) When accelerating the vehicle, the fluid resistance of the electromagnetic variable throttle valves in the front and rear wheel suspension systems is increased to suppress vertical vibration of the vehicle body, and at the same time, the oil in the hydraulic shock absorbers of the front wheel suspension system is returned to the oil tank to reduce the amount of oil at the front of the vehicle body. By lowering the unsprung height of the vehicle, and supplying pressure oil from the hydraulic source to the hydraulic shock absorber of the rear wheel suspension system, the unsprung height of the rear of the vehicle body is increased, thereby suppressing the rearward tilt of the vehicle body due to rearward movement of the vehicle load. Therefore, driving performance is improved.

(b) When the acceleration is smaller than a predetermined value, for example when driving on a highway or uphill road where the engine speed is high (intake negative pressure is large), the electromagnetic variable throttle valve and electromagnetic directional control valve operate normally. It maintains a soft ride as an air spring and does not cause unnatural movements.

(c) The electromagnetic variable throttle valve and the electromagnetic directional control valve are controlled based on signals from the vehicle speed sensor and engine speed sensor, so they share the same vehicle speed sensor and engine speed sensor, which are widely used to control engine operation. This can reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for clearly demonstrating the present invention.
Fig. 2 is a configuration diagram of a hydroneumatic suspension system according to an embodiment of the present invention, Fig. 3 is a plan view showing the arrangement of a vehicle speed sensor and an intake negative pressure sensor, and Fig. 4 is a diagram showing the principle of an electromagnetic variable throttle valve. Figure 5 is a cross-sectional view of the same plane, Figure 6 is a plan view of the valve plate in the variable throttle valve, Figure 7 is software for controlling the electromagnetic variable throttle valve and the electromagnetic directional control valve. It is a flow chart explaining wear. 1... Front wheel suspension system, 2... Air spring, 5, 9
...Oil chamber, 6...Rod, 7...Cylinder, 8...
...Piston, 12...Electromagnetic variable throttle valve, 14...
Intake negative pressure sensor, 15...Vehicle speed sensor, 16...
Vehicle height sensor, 21... Rear wheel suspension system, 24... Electronic control device, 27, 37... Electromagnetic directional control valve, 3
1... Oil tank, 36... Pressure accumulator, 45... Acceleration operation state detector, 46... Acceleration detector, 48... Engine rotation speed sensor.

Claims (1)

[Claims] 1. The oil chamber of the hydraulic shock absorber of each wheel is communicated via an electromagnetic variable throttle valve to the oil chamber of the air spring partitioned by a diaphragm, and the oil chamber of each hydraulic shock absorber is connected via an electromagnetic directional control valve to the hydraulic source and the oil tank. It is equipped with an electronic control device that controls the electromagnetic directional control valve and the electromagnetic variable throttle valve based on signals from the acceleration detector and the engine speed sensor, which determine longitudinal acceleration from changes in the vehicle speed sensor signal. When the acceleration while the vehicle is moving forward is greater than a predetermined value, each electromagnetic directional control valve is switched to connect the oil chamber of the front wheel hydraulic shock absorber to the oil tank and the oil chamber of the rear wheel hydraulic shock absorber to the hydraulic power source. , and a hydroneumatic suspension system characterized in that the lower the engine speed, the more each electromagnetic variable throttle valve is throttled.