JPH07228122A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To restrain oscillation from being overlapped, in a suspension device provided with a constriction means which holds and has held the correction values of the spring constant of an air spring and the damping force of a shock absorber, by making an attitude controller maintain a succeeding correction value when the succeeding correction value is indicated. CONSTITUTION:Supporting a vehicle body and buffering against a road surface are carried out for respective wheels by an air spring 1 and a shock absorber 2. When the correction values of spring constant and damping force suitable to restrain an attitude change with a driving condition while the vehicle body is being driven is indicated onto an attitude controller 3, such control and holding as increase or decrease the spring constant and the damping force are carried out according to the above details, so the attitude change in the vehicle body is restrained. After the completion of holding it, the constriction means 4 is started and the spring constant is maintained low by a prescribed time, so a reactive shock by the reaction of the air spring 1 generated after the attitude change is minimized. By maintaining the damping force of the shock absorber 2 high, it is possible to carry out constriction of the reactive shock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device for a vehicle, in which a spring constant and a damping force of the suspension are changed according to a running condition to suppress a swing of a vehicle body.

[0002]

2. Description of the Related Art Various swings occur in a vehicle body depending on the running condition of the vehicle. For example, rolling occurs due to lateral centrifugal force acting on the vehicle body when turning the vehicle. Further, the squat occurs because a backward inertial force acts on the vehicle body when the vehicle is started. Further, the nose dive occurs because a forward inertial force acts on the vehicle body when the vehicle is braked.

Conventionally, various suspension devices have been proposed as devices for suppressing the swing of the vehicle body and improving the riding comfort. FIG. 6 is a diagram showing an example of a conventional suspension device.

In the figure, an air spring 63 is interposed between the vehicle body 61 and the wheel 62, and the air spring 63 is connected to the communication valve 6
4 to the sub tank 65. Further, a shock absorber 66 is provided in parallel with the air spring 63.

In such a structure, by opening and closing the communication valve 64, the equivalent air capacity of the air spring 63 can be increased or decreased and the spring constant of the air spring 63 can be switched.

Although not shown, inside the shock absorber 66, oil moves along with the vertical movement of the piston portion. The passage amount of the oil is switched by a plurality of orifices inside. The damping force of the shock absorber 66 can be switched by switching the orifice with electromagnetic force.

In such a suspension device, by setting both the spring constant and the damping force to be low during normal traveling, a sporadic fluctuation of the road surface is buffered and a comfortable riding comfort is secured.

On the other hand, with respect to the swing generated in the vehicle body, first, the change in the posture of the vehicle body is suppressed. When the vehicle turns, brakes, or starts, the vehicle body receives an inertial force, so the vehicle body tilts in the direction of the force and the attitude of the vehicle body changes. In order to suppress the posture change, the suspension device described above increases the spring constant of the air spring on the side where the vehicle body is tilted to reduce the contraction of the air spring. Therefore, the inclination of the vehicle body is reduced, and the change in the attitude of the vehicle body is suppressed.

Further, in the above-described suspension device, the damping force of the shock absorber is uniformly switched to a high value to slow the leaning speed of the vehicle body and suppress the posture change of the vehicle body.

As described above, during turning, braking, or starting, the change in the posture of the vehicle body is suppressed, and then the rebounding convergence is performed. After turning, braking, or starting, the inertial force that tilts the vehicle body disappears, and the rebounding force of the expanded and contracted air spring causes a swingback. In the suspension device described above, the spring constant of the air spring is reduced in order to suppress the rocking back, thereby reducing the repulsive force and suppressing the occurrence of the rocking back.

Further, as disclosed in Japanese Utility Model Laid-Open No. 62-67816, Japanese Utility Model Laid-Open No. 62-181413 and Japanese Utility Model Laid-Open No. 62-181414, it is sufficient to converge the swing-back. By keeping the damping force of the shock absorber high for a predetermined time, the convergence of swinging back can be accelerated.

As described above, in the above-described suspension device, the rocking that occurs in the vehicle body is suppressed by the procedures of "suppressing the change in the posture of the vehicle body" and "converging the swing back".

[0013]

However, such a conventional suspension device has a problem when the swing of the vehicle body overlaps.

FIG. 7 is a conventional operation timing chart. The posture change is suppressed according to the left turn of the vehicle (see FIG.
), And the convergence of swinging back is achieved for a predetermined time T (FIG. 7).

If the brake is applied while the vehicle is being braked while the swing is being suppressed (see FIG. 7).
), The suppression of the rocking caused by the braking is started after the lapse of the predetermined time T (FIG. 7).

As described above, in the case where the swings overlap, the preceding swings are converged, so that the suppression of the subsequent swings is delayed. During that period, the spring constant of the air spring is low, so the posture change of the vehicle body due to subsequent rocking cannot be sufficiently suppressed, the riding comfort of the occupant is poor, and the steering wheel is robbed by the vehicle body rocking. , The steering stability deteriorates.

An object of the present invention is to provide a suspension device for a vehicle which can suppress the swing even when the swings of the vehicle body occur repeatedly.

[0018]

FIG. 1 is a block diagram showing the principle of the present invention. INDUSTRIAL APPLICABILITY The present invention is installed between a vehicle body and a plurality of wheels, respectively, and an air spring 1 whose spring constant can be increased / decreased, and is interposed between a vehicle body and a plurality of wheels, and its damping force can be increased / decreased. The shock absorber 2 and the correction values of the spring constant and the damping force suitable for suppressing the posture change of the vehicle body depending on the running condition are instructed, and the air spring 1 and the shock absorber 2 are controlled to hold the correction value. In the suspension device for a vehicle, which includes the attitude control means 3 for performing the above-mentioned operation and the converging means 4 for keeping the spring constant low and the damping force high for a predetermined time after the end of the holding, When the subsequent correction value is instructed during the above-mentioned predetermined time, the convergence means 4
Further, it is characterized by including control means 5 for stopping the operation for keeping the spring constant low and keeping the damping force high, and for causing the attitude control means 3 to hold the subsequent correction value.

[0019]

In the suspension device according to the present invention, the vehicle body is supported for each wheel by the air spring 1 and the shock absorber 2 described above, and the vehicle body and the road surface are buffered.

When the vehicle is traveling, the posture of the vehicle body changes depending on the traveling situation. When the attitude control means 3 is instructed of the spring constant and the correction value of the damping force suitable for suppressing the change in the attitude, the attitude control means 3 causes the above-mentioned spring constant and damping force according to the instructed contents. Since the control for increasing and decreasing and the holding are performed, the change in the posture of the vehicle body is suppressed.

Further, after the end of the holding, the converging means 4 is activated and the spring constant of the air spring is kept low for a predetermined time. Therefore, the rebound due to the repulsive force of the air spring which occurs after the above-mentioned posture change is reduced. Also, by keeping the damping force of the shock absorber 2 high, the convergence of the swaying is performed quickly.

Further, when the subsequent correction value is instructed at the end of the above-mentioned holding or during the predetermined time, the posture of the posture is controlled by the above-mentioned control means 5 without waiting for the end of the above-mentioned predetermined time. The control means 3 immediately starts holding the subsequent correction value.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing an embodiment of the present invention.

In the figure, an air spring 13a is interposed between the vehicle body 11 and the front right wheel 12a, and the air spring 13a is connected to the sub tank 15a via a communication valve 14a. A shock absorber 16a is interposed in parallel with the air spring 13a.

The vehicle body 11 and the wheels 12b, 12c,
Since the configuration arranged between 12d and 12d is the same as the configuration described above, the corresponding components are indicated by the same reference numerals with subscripts "b, c, d", and description thereof will be omitted.

A mode changeover switch 17, a steering angle sensor 18 and a foot brake switch 19 are arranged in the driver's seat. A lateral acceleration sensor 21 and a vertical acceleration sensor 22 are arranged in the front part of the vehicle body 11,
A back lamp switch 23 and a vehicle speed sensor 24 are arranged in the rear part of the vehicle 1.

Further, the above-mentioned communication valves 14a, 14b, 1
Each output terminal of the microcomputer 25 is connected to a control terminal for opening and closing 4c, 14d and a control terminal for switching the damping force of each shock absorber 16a, 16b, 16c, 16d. The output terminals of the mode changeover switch 17, the steering angle sensor 18, the foot brake switch 19, the lateral acceleration sensor 21, the vertical acceleration sensor 22, the back lamp switch 23, and the vehicle speed sensor 24 are respectively connected to the input terminals of the microcomputer 25. Connected.

Regarding the correspondence between this embodiment and the principle block diagram shown in FIG. 1, the air springs 13a to 13d,
Communication valves 14a to 14d and sub tanks 15a to 15d
Corresponds to the air spring 1, and shock absorbers 16a to 16a
6d corresponds to the shock absorber 2, and the microcomputer 25 corresponds to the attitude control means 3, the convergence means 4 and the control means 5.

The microcomputer 25 takes in the outputs of the above-mentioned sensors and performs the "judgment of the running condition" according to the following items. For turning the vehicle to the left, the vehicle speed sensor 24 detects that the vehicle is running, the steering angle sensor 18 detects left rotation of the steered wheels, and the lateral acceleration sensor 21 detects a centrifugal force to the right. It is judged from. When the vehicle turns to the right, the vehicle speed sensor 24 detects that the vehicle is running (the left and right are reversed from the above conditions), the steering angle sensor 18 detects the right rotation of the steered wheels, and the lateral acceleration sensor It is determined from the condition for detecting the centrifugal force from 21 to the left. For braking when the vehicle is moving forward, the vehicle speed sensor 24 detects that the vehicle is running, the foot brake switch 19 detects the depression of the brake, and the back lamp switch 23 is used.
Is determined from the condition for detecting the non-lighting of the back lamp. For braking when the vehicle is moving in reverse, the vehicle speed sensor 24 detects that the vehicle is running, and the foot brake switch 19 detects the depression of the brake.
Is determined from the condition for detecting the lighting of the back lamp.

When such a traveling situation is detected, as shown in FIG. 3, the microcomputer 25 controls the postures of. In response to the vehicle turning to the left, the microcomputer 25 increases the damping force of the shock absorbers 16a, 16b, 16c, 16d and closes the communication valves 14a, 14c.
The spring constants of the air springs 13a, 13c on the right side of the vehicle body are increased to suppress changes in the vehicle body posture due to centrifugal force. In response to the vehicle turning to the right, the microcomputer 25 increases the damping force of the shock absorbers 16a, 16b, 16c, 16d and closes the communication valves 14b, 14d.
The spring constants of the air springs 13b and 13d on the left side of the vehicle body are increased to suppress changes in the attitude of the vehicle body due to centrifugal force. In response to braking when the vehicle is moving forward, the microcomputer 25 increases the damping force of the shock absorbers 16a, 16b, 16c, 16d, closes the communication valves 14a, 14b, and closes the air springs 13a, 13b in front of the vehicle body. The spring constant is increased to suppress the posture change of the vehicle body due to inertial force. The microcomputer 25 increases the damping force of the shock absorbers 16a, 16b, 16c, 16d in response to the braking of the vehicle in reverse, and closes the communication valves 14c, 14d so that the air springs 13c, 13d at the rear of the vehicle body are closed. The spring constant is increased to suppress the posture change of the vehicle body due to inertial force.

After the period in which the running condition is detected as described above ends, the microcomputer 25 converges the swing back. First, the microcomputer 25 keeps the damping force of the shock absorbers 16a, 16b, 16c, 16d high for a predetermined time to converge the swing back. Furthermore, communication valve 1
By making 4a, 14b, 14c and 14d open, the repulsive force of the air springs 13a, 13b, 13c and 13d is reduced, and the swing back is reduced.

The feature of the present embodiment is that the microcomputer 25 causes the above-mentioned "judgment of running condition"-"body posture control"-
And "convergence of swingback" in the following order. FIG. 4 is an operation flowchart of this embodiment.

FIG. 5 is an operation timing chart of this embodiment. Hereinafter, description will be given based on FIGS. 2 to 5. The microcomputer 25 takes in each output of the mode changeover switch 17, the steering angle sensor 18, the foot brake switch 19, the lateral acceleration sensor 21, the vertical acceleration sensor 22, the back lamp switch 23, and the vehicle speed sensor 24 (FIG. 4S).
1). If the mode changeover switch 17 is in the off state, the microcomputer 25 ends without controlling the swing described later (S2 in FIG. 4).

On the other hand, if the mode changeover switch 17 is in the ON state, the microcomputer 25 determines whether the vehicle is turning (FIG. 4S3). Rolling is suppressed (Fig. 4 S4).

Conventionally, the convergence of swinging back is performed after the end of the turning traveling, but in the present embodiment, the microcomputer 25 performs an operation for judging braking (FIG. 4S5), and the braking of the vehicle is not detected. After confirming, the convergence of swinging back is performed (S7 in FIG. 4), and the process ends.

If braking of the vehicle is detected (see FIG. 4)
S5), the microcomputer 25 promptly controls the posture during braking,
Is performed to suppress the inclination of the vehicle body (S6 in FIG. 4). After that, convergence of swinging back is performed (S7 in FIG. 4), and the process ends.

On the other hand, in the above, when the turning traveling is not detected (FIG. 4S3), the microcomputer 25 performs the operation of judging the braking (FIG. 4S8), and when the braking is not detected, the swing is not suppressed. To end the operation.

When braking is detected, the microcomputer 25 controls the posture during braking to suppress the inclination of the vehicle body (S6 in FIG. 4). After that, convergence of swinging back is performed (S7 in FIG. 4), and the process ends.

With this operation, when the vehicle is braked during turning (FIG. 5), the posture change of the vehicle body due to the braking is promptly suppressed after the turning is completed (FIG. 5). ).

In the present embodiment, the operation of judging the braking before converging the swing reversal of the turning traveling has been described. For example, the microcomputer 25 repeatedly repeats during the period of converging the swing reversal. If the vehicle is in each of the traveling situations, the microcomputer 25 promptly cancels the above-mentioned convergence of the swing-back and shifts to the above-mentioned "vehicle body attitude control"-. Is also good. By such an operation, the posture change of the following vehicle body can be promptly suppressed regardless of the order of each traveling situation.

Further, in the present embodiment, the microcomputer 25 determines the traveling condition by the above-mentioned sensors and gives the correction values for the spring constant and the damping force. However, the operation for determining the traveling condition and the correction value It is a matter of course that the driver may perform all or part of the operation of instructing.

[0042]

As described above, according to the present invention, when the vehicle body is swung during traveling, the following swinging is swiftly suppressed. Motion is suppressed.

Therefore, in the vehicle to which the present invention is applied, the riding comfort of the occupant during traveling is improved, and the steering stability is improved because the steering wheel is not robbed by the swing.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing a correspondence between a traveling situation and attitude control.

FIG. 4 is an operation flowchart of the present embodiment.

FIG. 5 is an operation timing chart of the present embodiment.

FIG. 6 is a diagram showing a conventional suspension device.

FIG. 7 is a conventional operation timing chart.

[Explanation of symbols]

 1, 13 Air Spring 2, 16 Shock Absorber 3 Attitude Control Means 4 Convergence Means 5 Control Means 11 Vehicle Body 12 Wheels 14 Communication Valve 15 Sub Tank 17 Mode Changeover Switch 18 Steering Angle Sensor 19 Foot Brake Switch 21 Lateral Acceleration Sensor 22 Vertical Acceleration Sensor 23 Back lamp switch 24 Vehicle speed sensor 25 Microcomputer

Claims (1)

[Claims] 1. An air spring 1, which is interposed between a vehicle body and a plurality of wheels, and whose spring constant can be increased and decreased, and an air spring 1, which is interposed between the vehicle body and the plurality of wheels, respectively.
Further, a shock absorber 2 capable of increasing / decreasing the damping force, the spring constant and the correction value of the damping force suitable for suppressing the posture change of the vehicle body depending on the running condition are instructed,
Attitude control means 3 that controls the air spring 1 and the shock absorber 2 to hold the correction value, and a convergence means that keeps the spring constant low and keeps the damping force high for a predetermined time after the end of the holding. In the suspension device for a vehicle, the spring constant of the converging means 4 is kept low and the damping force is reduced when the subsequent correction value is instructed at the end of the holding or during the predetermined time. A suspension device for a vehicle, comprising: a control means 5 for stopping the operation of keeping the height higher and for causing the attitude control means 3 to hold a subsequent correction value.