JP2988651B2 - Vehicle suspension control device - 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 device for a vehicle capable of raising and lowering a vehicle body when the vehicle is stopped and capable of suppressing roll (hereinafter, referred to as "roll") when the vehicle is raised and lowered.

[0002]

2. Description of the Related Art In general, a sightseeing bus is provided with a passenger entrance at the front of a vehicle. Therefore, in order to make it easy for passengers to get on and off, a kneeling device that lowers the vehicle height at the front of the vehicle when the vehicle is stopped has been mounted on the front wheel suspension.

FIG. 4 is a diagram showing a conventional bus front wheel suspension. In the figure, an air spring 53 and a shock absorber 54 are interposed between a front wheel 51 and a vehicle body 52 in parallel, and the air spring 53 is ventilated to a sub-tank 55 via a control valve 56. The air is vented to the leveling valve 57 via the leveling valve 58. The leveling valve 57 has a lever 59 connected to the axle and moving up and down according to the vehicle height. Inside the leveling valve 57, a valve communicating with the compressed air chamber side is provided;
A valve communicating with the atmosphere. In addition, the air spring 53
It communicates with the compressed air chamber via the supply valve 60 and the exhaust valve 61
Through to the atmosphere side.

FIG. 5 is a diagram showing a conventional suspension of the entire bus. The front wheel suspensions 62a and 62b have the same configuration as in FIG.

In the figure, the configuration of the air system is such that compressed air of a compressor 63 is stored in a compressed air chamber 64,
This compressed air is supplied to the front wheel suspension 6 as described above.
2a and 62b, and supplied to the rear leveling valve 65. From the rear leveling valve 65, via the air chamber 66, the left and right rear air springs 6 are provided.
Vent to 7a and 67b.

The control system is configured such that a kneeling switch 21, a signal line indicating whether the side brake 22 is engaged, and a vehicle speed sensor 23 are connected to each input terminal of the microcomputer 20, and a leveling valve 58a , 58b, the air supply valves 60a, 60b, and the exhaust valves 61a, 61b, are connected to output terminals of the microcomputer 20.

The operation of kneeling in a conventional bus will be described below with reference to FIGS. 4 and 5. When the driver stops the vehicle and operates the kneeling switch 21 to select the descent of the vehicle body, the microcomputer 20 sets the leveling valve 58
a, 58b, close the air supply valves 60a, 60b and open the exhaust valves 61a, 61b. Therefore, the air springs 53a, 53
In 3b, the ventilation with the leveling valves 57a and 57b is cut off, and exhaust is performed to the atmosphere side. Therefore, the air springs 53a and 53b contract, and the vehicle height at the front part decreases.
At that time, the suspension of the rear wheel does not change, and the rear height of the rear wheel is maintained. Such an operation lowers the doorway at the front of the vehicle, and facilitates getting on and off the occupant.

Further, at the start of traveling, or when the driver operates the kneeling switch 21 to select raising the vehicle body, the microcomputer 20 closes the exhaust valves 61a and 61b and opens the air supply valves 60a and 60b. Therefore, the air spring 53
In a and 53b, the ventilation with the atmosphere side is cut off, and air is supplied from the compressed air chamber 64. Accordingly, the air springs 53a, 53
3b extends, and the front part of the vehicle rises. By such an operation, the vehicle height required for traveling from a state where the vehicle height has decreased,
Secured quickly.

During traveling, the microcomputer 20
, The air supply valves 60a and 60b and the exhaust valves 61a and 61b are closed, and the leveling valves 58a and 58b are opened. Although the leveling valve is publicly known and will not be described in particular, the supply and exhaust of the air springs 53a and 53b and the air springs 67a and 67b are adjusted by the leveling valves 57a and 57b and the rear leveling valve 65, and the vehicle height is within a specified value range. Is held.

[0010] Further, in the "vehicle height adjusting device of an air suspension vehicle" described in JP-A-61-247506,
By changing the damping force of the shock absorber to a small value during the kneeling operation, the drag when the vehicle body moves up and down is reduced, and the time required for the kneeling operation is shortened.

Although it does not perform kneeling,
In the "vehicle height adjusting device" described in Japanese Patent Application Laid-Open No. 61-268513, when the vehicle is stopped, the damping force of the shock absorber is largely switched to suppress the roll of the vehicle body.

[0012]

In such a kneeling operation, the left and right air springs of the front wheels are simultaneously supplied and exhausted. At this time, if a difference between the left and right supply / exhaust amounts occurs, a roll of the vehicle body occurs.

Further, in a sightseeing bus, since the occupant moves inside the vehicle immediately after the vehicle stops, the weight balance of the vehicle body changes during the kneeling, and the roll easily occurs.

When such a roll occurs, the occupant feels discomfort, and furthermore, the occupant easily loses his balance. In particular, the sightseeing bus crew, like the elderly and children,
Since many people are unfamiliar with the shaking of vehicles, measures to suppress the roll described above have been strongly demanded.

Further, in the above-mentioned "vehicle height adjusting device for an air suspension vehicle", the damping force of the shock absorber is reduced during the kneeling operation, so that the drag force against the roll is small. Therefore, the roll was likely to be large and hardly attenuated. For this reason, roll control measures have been demanded from the viewpoint of safety measures.

[0016] It is possible to increase the damping force of the shock absorber and suppress the roll as in the above-mentioned "vehicle height adjusting device". However, there is a disadvantage that the kneeling operation is slowed down because the resistance to the lifting of the vehicle body is increased. For this reason, there has been a demand for a roll restraining measure capable of rapidly performing the kneeling.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a suspension control device capable of rapidly performing a kneeling operation and suppressing a roll during a kneeling operation.

[0018]

According to the present invention, there is provided an air spring interposed between a vehicle body and front and rear wheels, and an air supply / exhaust means for supplying / exhausting air to / from the air spring interposed between the front wheels. A suspension control device for a vehicle, comprising: a kneeling control means for driving the air supply / exhaust means to raise and lower the vehicle body; and a ventilation path for ventilating between air springs interposed on the left and right sides of the rear wheel. A communication valve for opening and closing a road, and control means for closing the communication valve when the vehicle body is moved up and down by the above-mentioned kneeling control means and opening the communication valve after the completion of the movement of the vehicle body are characterized.

[0019]

In the vehicle suspension control device according to the present invention, during the kneeling operation, the communication valve is closed by the above-described control means, and the ventilation of the left and right air springs of the rear wheels is cut off. In this way, the exchange of air between the left and right, which is caused by the expansion and contraction of the air spring in the opposite phase to the left and right, is interrupted. Therefore, the rigidity of the rear wheel suspension in the lateral direction is increased, and the roll of the vehicle body is suppressed.

In addition, since the natural frequency of the front and rear suspensions with respect to the rolls is largely shifted due to the closing of the communication valve, when the rolls are generated, the rolls generated before and after the vehicle body have different periods, so that the vehicle body is twisted. Become. Therefore, the energy of the roll is almost consumed by the small torsional movement of the vehicle body, and the roll rapidly decays.

In addition, since the damping force of the shock absorber is not increased, the drag for raising and lowering the vehicle body is small, so that the kneeling operation is performed quickly. After the completion of the kneeling operation, the communication valve opens, so that the air springs on the left and right sides of the rear wheel communicate with each other, thereby returning to the state of the rear wheel suspension during traveling.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating the suspension according to the present embodiment.

The left and right front wheel suspensions 62a and 62b have the same configuration as the conventional bus front wheel suspension. In the figure, showing the configuration of the air system,
Air is supplied from the air springs 53a, 53b to the sub-tanks 55a, 55b via the control valves 56a, 56b, and furthermore, is supplied from the air springs 53a, 53b to the leveling valves 58a, 58b.
Are vented to the leveling valves 57a, 57b through Inside these leveling valves 57a and 57b,
It has a valve that communicates with the compressed air chamber 64 and a valve that communicates with the atmosphere. The air springs 53a and 53b are connected to the air supply valves 60a and
60b, and communicates with the compressed air chamber through the exhaust valve 61a,
It leads to the atmosphere side via 61b.

The compressed air from the compressor 63 is stored in a compressed air chamber 64. The compressed air is sent to the front wheel suspensions 62 a and 62 b and is also supplied to a rear leveling valve 65. The rear leveling valve 65 communicates with an air chamber 66, and the air stored in the air chamber 66 is ventilated to left and right rear wheel air springs 67a and 67b via communication valves 68a and 68b.

Next, the configuration of the control system will be described.
A zero input terminal is connected to a kneeling switch 21 that is manually operated in a driver's seat, a signal line indicating whether or not a side brake 22 is engaged, and a vehicle speed sensor 23.

The output terminal of the microcomputer 20 is connected to terminals for controlling the opening and closing of the leveling valves 58a and 58b, the supply valves 60a and 60b, the exhaust valves 61a and 61b, and the communication valves 68a and 68b.

FIG. 2 is a flowchart showing the operation of this embodiment. FIG. 3 is a timing chart of the operation of the present embodiment. Hereinafter, the operation of this embodiment will be described with reference to FIGS.

The microcomputer 20 determines whether or not the vehicle is stopped by judging the vehicle speed value from the vehicle speed sensor 23 and whether or not the side brake 22 is engaged (FIG. 2 S1, S2). When the vehicle is stopped, the microcomputer 20 captures the state of the kneeling switch 21 operated by the driver (S3 in FIG. 2). If the contact of the switch does not move (indicated as "OFF" in FIG. 2), the kneeling operation is performed. Exit without performing.

Further, by the driver's operation of the switch,
When the vehicle body is instructed to be lowered (indicated as "down" in FIG. 2), the microcomputer 20 determines whether or not a control signal for opening the exhaust valves 61a and 61b has been output (S4 in FIG. 2). If 61a and 61b are open, the vehicle height has already decreased, and the process ends without repeatedly lowering the vehicle body.

On the other hand, if the exhaust valves 61a and 61b are closed, the microcomputer 20 closes the leveling valves 58a and 58b, thereby causing the air springs 53a and 53b and the compressed air chamber 64 to close.
(S5 in FIG. 2) and the communication valves 68a, 68
8b is closed to block the air flow between the rear wheel air springs 67a and 67b (FIG. 2S6), (FIG. 3).

The microcomputer 20 waits for the required time Tdn to complete the operation of closing the valve (S7 in FIG. 2),
Thereafter, the microcomputer 20 opens the exhaust valves 61a and 61b,
The vehicle height is lowered by exhausting the left and right air springs 53a and 53b of the front wheels (S8 in FIG. 2).

The microcomputer 20 waits for the required time (Tpd-Tdn) to complete the above-mentioned operation of lowering the vehicle height (S9 in FIG. 2). Thereafter, the microcomputer 20 sets the communication valve 68
a, 68b to open the rear wheel air springs 67a and 67b.
Is ventilated (S10 in FIG. 2), and the descent of the vehicle body ends (FIG. 3).

On the other hand, when the vehicle is running or when the driver instructs the vehicle body to be raised by operating the switch (indicated as "up" in FIG. 2), the microcomputer 20 sets the exhaust valves 61a, It is determined whether or not a control signal to open 61b is output (S12 in FIG. 2). If the exhaust valves 61a and 61b are closed, the vehicle body has already risen, and the process is terminated without repeatedly raising the body. I do.

When the exhaust valves 61a and 61b are open, the microcomputer 20 closes the communication valves 68a and 68b to shut off the air flow between the rear wheel air springs 67a and 67b (S13 in FIG. 2) and to exhaust the air. The valves 61a and 61b are closed to shut off the ventilation between the air springs 53a and 53b and the atmosphere (FIG. 2S14), (FIG. 3).

The microcomputer 20 waits for a required time Tdn for completing the operation of closing the valve (S1 in FIG. 2).
5) After that, the microcomputer 20 opens the air supply valves 60a and 60b, supplies air to the left and right air springs 53a and 53b of the front wheels, and raises the vehicle height (S16 in FIG. 2).

The microcomputer 20 waits for the required time (Tpu-Tdn) to complete the above-described body lifting operation (S17 in FIG. 2). Thereafter, the microcomputer 20 sets the air supply valves 60a and 60a.
0b and open the communication valves 68a, 68b and the leveling valves 58a, 58b to return to the suspension state during traveling (FIGS. 2, S18, S19, S20).
The lifting of the vehicle body ends (FIG. 3).

The above-mentioned series of operations is repeated at all times or at predetermined intervals, so that the vehicle body is raised and lowered by kneeling. If a roll occurs during such a kneeling operation, the left and right air springs 67a and 67b on the rear wheel side expand and contract in opposite phases, and air is exchanged through a ventilation passage therebetween. However, in the present embodiment, the air flow between the rear wheel air springs 67a and 67b is shut off by the operation of closing the communication valves 68a and 68b which has not been conventionally performed.
The above-described exchange of air does not occur, the rigidity of the vehicle body with respect to the lateral force is increased, and the roll is suppressed.

Further, such communication valves 68a, 68b
, The natural frequencies of the front and rear suspensions with respect to the rolls are greatly shifted, so that rolls having different periods are generated between the front and rear suspensions, resulting in a twisting motion of the vehicle body. Therefore, the energy of the roll is consumed for the small torsional movement of the vehicle body,
Decays rapidly.

In this embodiment, the communication valve 68
The completion of the kneeling operation is determined based on the elapse of the required time in order to obtain the timing for opening the a and 68b. For example, the completion of the kneeling operation is detected by a displacement sensor or the like that detects the lever position of the leveling valves 57a and 57b. It may be determined.

In this embodiment, the switching of the damping force of the shock absorber is not described. Becomes possible.

Further, the damping force of the shock absorber may be increased during the kneeling operation, so that the roll can be further suppressed.

[0042]

As described above, according to the present invention, the kneeling can be performed quickly, and the roll accompanying the kneeling can be suppressed, so that the occupant can be prevented from falling and feeling uncomfortable.

Therefore, safety and comfort at the time of kneeling are enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a suspension according to an embodiment.

FIG. 2 is a flowchart illustrating the operation of the present embodiment.

FIG. 3 is a timing chart of the operation of the present embodiment.

FIG. 4 is a view showing a conventional front wheel suspension.

FIG. 5 is a view showing a conventional suspension.

[Explanation of symbols]

 Reference Signs List 20 microcomputer 21 kneeling switch 22 side brake 23 vehicle speed sensor 53 front wheel air spring 54 shock absorber 57 leveling valve 58 leveling valve 59 lever 60 air supply valve 61 exhaust valve 64 compressed air chamber 65 rear leveling valve 66 air chamber 67 rear wheel air spring 68 communication valve

Claims (1)

(57) [Claims] 1. An air spring interposed between a vehicle body and front and rear wheels, an air supply / exhaust unit for supplying / exhausting air of an air spring interposed on a front wheel side, and driving the air supply / exhaust unit. A suspension control device for a vehicle, comprising: a kneeling control unit that raises and lowers the vehicle body; and a ventilation path that ventilates between air springs provided on the left and right sides of a rear wheel. A suspension control device for a vehicle, comprising: control means for closing the communication valve when the vehicle body is moved up and down by the kneeling control means, and opening the communication valve after completion of the movement of the vehicle body.