JP2947327B2 - Suspension control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control system for vehicles such as trucks and buses, and more particularly to a suspension control system using both an air suspension and a hydraulic active suspension.

[0002]

2. Description of the Related Art In a large vehicle such as a truck or a bus, an air spring 3 and a hydraulic actuator 4 are provided between each wheel 1 and a vehicle body 2 as conceptually shown in FIG. Each air spring 3 is connected to an air tank 6 via a leveling valve 5 while the operating oil pressure in each hydraulic actuator 4 is positively increased or decreased from a neutral pressure by a hydraulic unit 7. While the vehicle is running, the vehicle 1 is adapted to constantly adjust the running posture of the vehicle body 2 in response to the fact that each wheel 1 undergoes a sudden load change from the road surface and tries to be vertically displaced.

However, since the operating oil pressure of the hydraulic actuator 4 of a large vehicle needs to be extremely high, if the hydraulic actuator 4 is kept at the high oil pressure even when the vehicle is at rest, the accuracy of each part of the hydraulic actuator 4 will be reduced. In addition to the increase in friction loss during operation of the hydraulic actuator 4 and an increase in trouble during vehicle maintenance, there are unfavorable aspects such as an increase in the number of steps required for maintenance of the vehicle. The vehicle body 2 is supported, and at this time, the height of the vehicle is kept constant by the action of the leveling valve 5.

However, conventionally, when the hydraulic pressure is supplied from the hydraulic unit 7 at the start of use of the vehicle, the hydraulic pressure in the hydraulic actuator 4 instantaneously increases from 0 to a neutral pressure, whereas the leveling valve 5 The speed at which air is discharged from each air spring 3 by operation is relatively slow, and it is impossible to follow the expansion of the hydraulic actuator 4 without time delay and reduce it. When the hydraulic pressure is released from the hydraulic actuator 4 at the end of use of the vehicle, the neutral pressure in the hydraulic actuator 4 instantaneously disappears. The speed at which air is supplied to each air spring 3 by the operation of the leveling valve 5 is also relatively slow. Te, can not be extended to follow without any time delay to the reduction of the hydraulic actuators 4,
A sudden drop in vehicle height was inevitable.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress a sudden change in vehicle height at the start and / or end of use of a vehicle in which an air suspension and a fluid pressure active suspension are used in combination. Is what you do.

[0006]

Therefore, a suspension control system according to the present invention includes an air spring installed between a vehicle body and wheels and connected to an air tank via a leveling valve, and an electromagnetic spring installed together with the air spring. A fluid pressure actuator connected to a fluid pressure source via a valve, and a control unit for the solenoid valve, wherein the control unit operates the solenoid valve at the start of use and / or at the end of use of the vehicle, and controls the fluid pressure. The fluid pressure in the actuator is controlled so as to gradually increase and / or decrease, respectively .
The solenoid valve operates while the vehicle is running.
The solenoid valve that controls the fluid pressure of the motor is shared .

[0007]

That is, the control unit operates the solenoid valve to control the fluid pressure in the fluid pressure actuator to gradually increase and decrease at the start and / or end of use of the vehicle. Even if the air supply / discharge action from the air spring due to the operation of the air spring is relatively gentle, a sudden change in the vehicle height is easily suppressed, and therefore, the air suspension and the fluid pressure active suspension are used in even at the time of the pause is to be withdrawn fluid pressure in the fluid pressure actuator, it can be constantly kept at a substantially constant vehicle height, moreover, the solenoid valves used during running of the vehicle
Solenoid valve that controls the fluid pressure of the fluid pressure actuator is shared
The introduction of this control system has
There is no cost increase.

[0008]

Embodiments of the present invention will be specifically described below. FIG. 1 shows a large vehicle such as a truck and a bus,
An air spring and a hydraulic actuator are respectively installed between the front and rear wheels and the vehicle body as in the case of the conventional device, and a control system on the hydraulic active suspension side when the air suspension and the hydraulic active suspension are used together is shown. The lower ends of the hydraulic actuators 10 and 11 are connected to left and right front wheels (not shown) via bushes 12, respectively.
3 are connected at their upper ends via mount insulators 14, and the hydraulic actuators 15 and 16 are connected at their lower ends to the left and right rear wheels (not shown) via bushes 12, respectively. An upper end is connected via an insulator 14, and a main accumulator 18 in which hydraulic oil is stored by a hydraulic pump 17 and each hydraulic actuator 10, 11, 1.
5 and 16 are connected to each other by an oil passage 19 and a rod upper joint 20 of each hydraulic actuator.
Each of 9 is provided with an electromagnetic proportional valve 21, a pressure sensor 22, and a gas spring 23 with a built-in damping valve.

On the other hand, the electronic control unit 30 is provided with a downstream oil passage 19 from each pressure sensor 22 to each electromagnetic proportional valve 21.
The internal oil pressure signals P1 to P4 are fed back, and a front axle vertical acceleration signal G is output from a sensor (not shown).
f, a rear axle left vertical acceleration signal GL and a rear axle right vertical acceleration signal GR are input, and control signals are sent from the electronic control unit 30 to the electromagnetic proportional valves 21, respectively. When each wheel is to be accelerated up and down due to a sudden load change from the road surface, each electromagnetic proportional valve 21 is operated by a control signal from the electronic control unit 30 corresponding to the acceleration signals Gf, GL and GR. And each hydraulic actuator 10,
The hydraulic pressure in 11, 15, and 16 is positively controlled to increase or decrease from the neutral pressure Po so as to adjust the running posture of the vehicle body and the riding comfort of the vehicle at all times.

[0010] In the above vehicle, the electronic control unit 3 is stopped when the vehicle is stopped for the same reason as in the conventional device.
In response to the control signal from 0, each of the electromagnetic proportional valves 21 is operated to release the hydraulic pressure from each of the hydraulic actuators 10, 11, 15, and 16, and the air springs are used to control the vehicle body 13
Is supported, and the vehicle height is maintained substantially constant by the action of a leveling valve (not shown). However, when the engine is to be started when the vehicle is started to be used, the electronic control unit 30 is controlled by the control flowchart shown in FIG. First, each hydraulic actuator 10, 11,
It is checked whether the hydraulic pressures in 15, 15 have reached the neutral pressure Po, and if they have not reached the neutral pressure Po, in the next step each hydraulic actuator 10, 11, 15, Each of the electromagnetic proportional valves 21 is operated by a control signal from the electronic control unit 30 so that the oil pressure in the cylinder 16 increases at the pressure increasing speed ΔP1, and this control cycle is repeated as appropriate, as shown in FIG. As described above, the hydraulic pressure in each of the hydraulic actuators 10, 11, 15, and 16 which was initially 0 gradually increases with the passage of time, and takes 85 to 10 minutes over about 1 to 2 minutes.
When the pressure reaches a neutral pressure Po of about 0 atm, the control operation of each electromagnetic proportional valve 20 is started by a control signal from the electronic control unit 30 as in the case of the conventional device, and each hydraulic actuator 10, 11, 15, 16 is controlled. The internal hydraulic pressure is positively controlled to increase or decrease from the neutral pressure Po, so that the running posture of the vehicle body and the riding comfort of the vehicle are always improved.

That is, at the start of use of the vehicle,
Each hydraulic actuator 10, 11, 1 which was initially 0
Since the oil pressure in the pumps 5 and 16 gradually increases to the neutral pressure Po at the pressure increasing speed ΔP1, the air discharge from the air spring due to the action of the leveling valve causes each hydraulic actuator 1
It is possible to sufficiently follow the increase in the oil pressure in 0, 11, 15, and 16 and easily realize the rise of the air springs and the hydraulic actuators 10, 11, 15, and 16 while keeping the vehicle height almost constant. As a result, unlike conventional cases, problems such as the extension of the air spring and the contact of the hydraulic actuators 10, 11, 15, and 16 with the stopper do not occur. Since it is possible to extend the vehicle length and prevent the vehicle height from suddenly increasing at the start of use of the vehicle, it is possible to greatly improve the usability of the vehicle as compared with the related art.

Each of the electromagnetic proportional valves 21 is operated by a control signal from the electronic control unit 30 during traveling of the vehicle, and is commonly used to adjust the traveling posture of the vehicle body to be always good. Therefore, the introduction of the above-mentioned control system does not particularly increase the cost, and thus has an advantage that it can be easily put into practical use.

Next, when the engine is stopped at the end of use of the vehicle, the electronic control unit 30 first sets the hydraulic pressure in each of the hydraulic actuators 10, 11, 15, 16 as shown in the control flowchart of FIG. Is checked to see if it is 0, and if they are not 0, the hydraulic pressure in each of the hydraulic actuators 10, 11, 15, and 16 in which the hydraulic pressure has not become 0 in the next step is reduced to the pressure reduction rate ΔP2.
Each electromagnetic proportional valve 21 is operated by a control signal from the electronic control unit 30 so as to fall down, and this control cycle is repeated as appropriate, so that the initial neutral pressure Po is reached as shown in FIG. When the hydraulic pressure in each of the hydraulic actuators 10, 11, 15, 16 gradually decreases with the passage of time, and reaches 0 over a period of several minutes, which is slightly longer than that at the time of starting the use of the vehicle, each electromagnetic The control operation of the proportional valve 21 ends.

At this time, the hydraulic pressure in each of the hydraulic actuators 10, 11, 15, and 16 which was initially the neutral pressure Po gradually decreases to 0 at the pressure reducing speed ΔP2, so that the air spring is moved from the air tank to the air spring by the action of the leveling valve. Air supply of each hydraulic actuator 10, 11, 15, 1
6 can sufficiently follow the decrease in the hydraulic pressure in the hydraulic actuators 10, 11, while maintaining the vehicle height almost constant.
Since the operations of the actuators 15 and 16 can be easily terminated, unlike the related art, troubles such as contact of the air springs and the hydraulic actuators 10, 11, 15, and 16 with stoppers do not occur. As in the case of the above, the maintenance of each part of the device is improved, and the life of the equipment can be easily extended, and the sudden decrease in the vehicle height at the end of use of the vehicle is suppressed. Can be remarkably improved as compared with the related art.

In the above embodiment, the control is performed at the start of use of the vehicle and at the end of use of the vehicle. However, the same control as described above is performed only at the start of use or at the end of use of the vehicle. In the above embodiment, the detection at the start of use of the vehicle and the end of use of the vehicle are performed by detecting the start operation and the stop operation of the engine, respectively. Needless to say, it can be detected by actuation or release of the parking brake, and in each of the above embodiments, a hydraulic active suspension is used. Can be replaced with a pneumatic device such as a pneumatic actuator that performs the same operation.

[0016]

In the suspension control system according to the present invention, even when the air suspension and the fluid pressure active suspension are used together in the vehicle, the control unit operates the solenoid valve at the start and / or end of use of the vehicle. The fluid pressure in the fluid pressure actuator is controlled so as to gradually increase and decrease, so that the vehicle height can be kept almost constant at all times. Can be easily extended, and a sudden change in vehicle height at the start of use and / or at the end of use of the vehicle is suppressed, so that the usability of the vehicle can be improved ,
In addition, the solenoid valve used is fluid
Solenoid valve that controls the fluid pressure of the pressure actuator is shared
And the introduction of this control system is particularly costly
Since it is not accompanied by a rise, it is extremely easy to put into practical use.
There is a place.

[Brief description of the drawings]

FIG. 1 is a main part control system diagram in an embodiment of the present invention.

FIG. 2 is a control flowchart of the embodiment.

FIG. 3 is a control explanatory diagram of the embodiment.

FIG. 4 is a control flowchart of the above embodiment.

FIG. 5 is a control explanatory diagram of the embodiment.

FIG. 6 is a conceptual layout diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic actuator 11 Hydraulic actuator 15 Hydraulic actuator 16 Hydraulic actuator 19 Oil passage 21 Electromagnetic proportional valve 22 Pressure sensor 30 Electronic control unit Po Neutral pressure ΔP1 Pressure increase speed ΔP2 Pressure decrease speed

Claims (2)

(57) [Claims] 1. An air spring installed between a vehicle body and a wheel and connected to an air tank via a leveling valve, a fluid pressure actuator provided together with the air spring and connected to a fluid pressure source via an electromagnetic valve, and A control unit for the solenoid valve, wherein the control unit operates the solenoid valve at the start and / or end of use of the vehicle so that the fluid pressure in the fluid pressure actuator gradually increases and / or decreases, respectively. Control the above solenoid valve
While the vehicle is running, the fluid pressure of the fluid pressure actuator is controlled.
A suspension control system that shares a solenoid valve to control. 2. The vehicle according to claim 1, wherein the fluid pressure in the fluid pressure actuator is maintained at a substantially constant height by discharging air from the air spring and / or replenishing air by the leveling valve. , A suspension control system that controls to gradually ascend and / or descend, respectively.