JPH07232533A - Suspension device of vehicle - Google Patents

Abstract

PURPOSE:To restrain oscillation generated on a car body superimposed concerning a suspension device of a vehicle changing spring constant and damping force. CONSTITUTION:This is concerning a suspension device of a vehicle furnished with an air spring 1 respectively interposed between a car body and a plural number of wheels and capable of increasing and decreasing spring constant, a shock absorber 2 respectively interposed between the car body and a plural number of the wheels and capable of increasing and decreasing damping force and an oscillation restraining means 3 instructed the spring constant suitable for restraining oscillation of the car body due to a traveling status and a correction value of the damping force and to carry out maintenance of the correction value by way of varying the spring constant and the damping force. It is furnished with an instruction means 4 to instruct the maximum value for each wheel of the correction value for each oscillation to the oscillation restraining means 3 in accordance with the traveling status where oscillation is superimposed.

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 varied according to a running condition to suppress a swing of a vehicle body.

[0002]

2. Description of the Related Art In a vehicle, various swings occur in the vehicle body depending on the running condition. For example, rolling occurs due to lateral centrifugal force acting on the vehicle body when turning the vehicle. In addition, squats, when starting the vehicle,
It occurs because of the inertial force acting in the backward direction. Further, the nose dive is caused by inertial force acting in the forward direction when braking the vehicle.

Conventionally, various suspension devices have been proposed as a device for suppressing this type of swinging. Figure 7
It is a figure which shows an example of the conventional suspension apparatus.

In the figure, an air spring 73 is interposed between the vehicle body 71 and the wheels 72, and the air spring 73 is a communication valve 74.
Is connected to the sub tank 75 via. A shock absorber 76 is provided in parallel with the air spring 73.

In such a structure, by opening and closing the communication valve 74, the equivalent air capacity of the air spring 73 can be increased or decreased, and the spring constant of the air spring 73 can be switched.

Inside the shock absorber 76, although not shown, oil passes through a plurality of orifices (holes) as the piston portion moves up and down. The damping force of the shock absorber 76 can be switched by opening and closing the orifice with a solenoid valve.

The switching of the spring constant and the damping force is performed as follows. During normal driving,
By setting both the spring constant and damping force low,
A comfortable ride is secured by buffering the sporadic road surface fluctuations.

When the vehicle turns, brakes, or starts, the vehicle body receives an inertial force, so that the vehicle leans in the direction of the force.
The body posture changes. In order to suppress the change in posture, the spring constant of the air spring on the vehicle body inclining side is increased to reduce the contraction of the air spring. As a result, the inclination of the vehicle body is reduced, and changes in the attitude of the vehicle body are suppressed.

Further, by uniformly changing the damping force of the shock absorber to a high value, it is possible to slow the leaning speed of the vehicle body and suppress the posture change of the vehicle body. Thus, during turning, braking or starting, the change in the attitude of the vehicle body is first suppressed.

After the turning, braking, or starting of the vehicle is completed, the inertial force that tilts the vehicle body disappears, so that the rebounding force of the expanded and contracted air spring causes the vehicle to swing back. In order to suppress the rocking back, the spring constant of the air spring is reduced to reduce the repulsive force and the occurrence of rocking back.

Further, by keeping the damping force of the shock absorber high for a predetermined time sufficient to perform the convergence of the swing-back, the convergence of the swing-back can be quickly performed (Actually published 62-67816). No. Gazette, Jitsukai Sho 62-1
No. 81413 and No. 62-181414.

As described above, the swing is suppressed by a procedure of first suppressing the change in the attitude of the vehicle body and then converging the swing back. For example, when the vehicle turns left, the spring constant on the right side of the vehicle body is increased and the damping force is uniformly increased to suppress the inclination to the right due to the centrifugal force (FIG. 8).

Furthermore, after the vehicle turns to the left, the spring constant on the right side of the vehicle body is reduced and the damping force is kept high for a predetermined time T, whereby convergence of swinging back is achieved (FIG. 8).

The above-mentioned control for switching the spring constant and the damping force is performed by the driver, or by a microcomputer or the like that monitors the traveling condition.

[0015]

However, in such a conventional suspension device, for example, when the brake is applied while the preceding swing is being suppressed and the vehicle is braked (FIG. 8). The suppression of the rocking caused by this braking is started after the convergence of the preceding rocking (FIG. 8).
).

As described above, in the case where the swings occur in a superimposed manner, the preceding swings are suppressed, so that the subsequent swings are suppressed. During that period, the change in the posture of the vehicle body due to the subsequent swinging is not suppressed, so the riding comfort of the occupant is poor, and the steering stability is deteriorated because the steering wheel is taken away by the swinging of the vehicle body.

It is an object of the present invention to provide a vehicle suspension device capable of promptly and effectively suppressing the swing generated by being superposed on the vehicle body.

[0018]

FIG. 1 is a block diagram showing the principle of the present invention. The present invention relates to an air spring that is interposed between a vehicle body and a plurality of wheels and has a spring constant that can be increased or decreased.
(1), and is interposed between the vehicle body and multiple wheels,
In addition, the shock absorber (2) that can increase or decrease the damping force and the above-mentioned spring constant and damping force correction value suitable for suppressing the swing of the vehicle body due to running conditions are instructed. In a suspension device for a vehicle, which is provided with rocking suppressing means (3) that increases and decreases and holds the correction value, according to a traveling situation where the rocking overlaps, each wheel having the above-mentioned correction value for each rocking. In addition, an instructing means (4) for instructing the rocking suppressing means (3) of the maximum value in is added.

[0019]

In the suspension device according to the present invention, the air spring (1) and the shock absorber (2) support the vehicle body for each wheel and cushion the vehicle body and the road surface.

On the other hand, the vehicle body tilts depending on the running condition, and then swings back. The values of the spring constant and the damping force that suppress the inclination, or the values of the spring constant and the damping force that quickly converge the swing back are designated as the correction values. The rocking | swiveling suppression means (3) suppresses rocking | fluctuation of a vehicle body by performing control and hold which increase / decrease the above-mentioned spring constant and damping force according to the correction value.

Further, in a traveling condition in which the swings overlap, the resultant force of a plurality of inertial forces acts on the vehicle body, tilts the vehicle body in the direction of the resultant force, and causes a complicated swinging back. Instruction means
In (4), the maximum value for each wheel of the correction values corresponding to each superposed rocking is selected, and the rocking suppressing means (3) is instructed as the correction value. The rocking suppressing means (3) controls and holds the above-mentioned spring constant and damping force to be increased or decreased according to the correction value, thereby suppressing the inclination in the direction in which the resultant force acts, or converging the shaking back. Is done. Therefore, the superimposed swing is suppressed.

[0022]

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. An air spring 13 is provided between the vehicle body 11 and the front right wheel 12a.
A shock absorber 16a is provided in parallel with a.

The vehicle body 11 and the other wheels 12b, 12
An air spring and a shock absorber are also arranged between c and 12d, but since the structure is the same as the structure described above,
Subscripts "b", "c", and "d" are attached to corresponding components.
The same reference number is used for the description, and the description is omitted.

A mode changeover switch 17, a steering angle sensor 18 and a footbrake 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, and a back lamp switch 23 and a vehicle speed sensor 24 are arranged in the rear part of the vehicle body 11.

Further, the communication valves 14a, 14b, 14c,
Control terminals for opening and closing 14d and shock absorbers 1
The output terminals of the microcomputer 25 are connected to the control terminals for switching the damping forces of 6a, 16b, 16c and 16d. Each of the input terminals of the microcomputer 25 has a mode changeover switch 17, a steering angle sensor 18, a foot brake switch 19, a lateral acceleration sensor 21, and a vertical acceleration sensor 2 described above.
2. The output terminals of the back lamp switch 23 and the vehicle speed sensor 24 are connected to each other.

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-
16d corresponds to the shock absorber (2) and the microcomputer 2
Reference numeral 5 corresponds to the rocking suppressing means (3) and the indicating means (4).

FIG. 3 is an operation flowchart of this embodiment. The operation of this embodiment will be described below with reference to FIGS. 2 and 3. The microcomputer 25 detects from the vehicle speed sensor 24 that the vehicle is traveling, the steering angle sensor 18 detects the right rotation angle of the steered wheels, and the lateral acceleration sensor 21 detects the centrifugal force in the left direction. Turn right ”. (S1).

When the result of the judgment indicates "right turn of the vehicle", the microcomputer 25 sets the right roll flag set in the internal storage device (S2). On the contrary, when the "right turn of the vehicle" is not indicated, the right roll flag is reset (S3).

Further, the microcomputer 25 detects that the vehicle is running from the vehicle speed sensor 24 (in the opposite direction to the above condition).
Moreover, the left rotation angle of the steered wheels is detected from the steering angle sensor 18,
Further, from the condition for detecting the centrifugal force in the right direction from the lateral acceleration sensor 21, "turn left of the vehicle" is determined (S4).

If the result of the determination indicates "turn left of the vehicle", the microcomputer 25 sets the left roll flag set in the internal storage device (S5). On the contrary, when the "right turn of the vehicle" is not indicated, the left roll flag is reset (S6).

Further, the microcomputer 25 uses the vehicle speed sensor 24.
It is detected that the vehicle is running and the foot brake switch 19
From the condition that the brake pedal is depressed and the back lamp is turned off by the back lamp switch 23, "vehicle braking" is determined (S7).

If the result of the determination indicates "vehicle braking", the microcomputer 25 sets the braking flag set in the internal storage device (S8). On the contrary, when the "vehicle braking" is not indicated, the braking flag is reset (S9).

Further, the period from the completion of the detection of the right turn, the left turn and the braking described above until the microcomputer 25 advances the register of the internal storage device until the register reaches a predetermined value ( (A period sufficient for convergence) is determined as "shaking back" (S10).

If the result of the determination indicates "rocking back", the microcomputer 25 sets the rocking back flag set in the internal storage device (S11). On the other hand, if "sway back" is not indicated, the swing back flag is reset (S12).

As described above, the microcomputer 25 determines the traveling condition and updates the internal flag. Next, the microcomputer 25
Composes the correction values of the spring constant and the damping force as follows.

FIG. 4 is a diagram showing the correspondence between the traveling condition and the correction value. In this figure, the spring constant and the correction value of the damping force corresponding to a single traveling situation are shown. Microcomputer 2
5 selects the correction value corresponding to the set state of the flag,
The correction values are combined by the procedure of selecting the maximum value of the correction values for each wheel (S13).

Next, the microcomputer 25 uses the communication valves 14a-1.
4d and the shock absorbers 16a to 16d are controlled to change the spring constant and the damping force to the above-described combined correction value (S14).

The microcomputer 25 repeats the above series of operations. FIG. 5 is an operation timing chart of this embodiment. FIG. 6 is a diagram showing an example of the combined correction values of this embodiment.

By the above-described operation, for example, when the brake is applied while the vehicle is turning to the left and the braking is applied (FIG. 5), the microcomputer 25 sets the left roll flag and the braking flag by judging the running condition. The microcomputer 25 selects the left turn correction value and the braking correction value corresponding to the set flag, and the correction value combined in the above procedure (FIG. 6).
Ask for. Based on the instruction of the correction value, the microcomputer 25
Increases the damping force uniformly and increases the spring constants of both front wheels and rear right wheel. Therefore, the resultant tilt of the vehicle body is suppressed by resisting the resultant force of the inertial force acting diagonally forward right of the vehicle body.

Next, when the vehicle turns left (see FIG. 5).
), The microcomputer 25 sets the shake-back flag and the braking flag according to the determination of the running condition, and instructs the correction value. The microcomputer 25 combines the instructed shake-back correction value and the braking correction value in the above-described procedure to uniformly increase the damping force and increase the spring constants of both front wheels. Therefore, the leaning of the vehicle body due to braking is suppressed without leaving time to converge the swing back.

Further, when the braking of the vehicle is completed (see FIG. 5).
), The microcomputer 25 sets the swing-back flag according to the determination of the running condition, and instructs only the swing-back correction value. The microcomputer 25 uniformly increases the damping force and uniformly decreases the spring constant based on the instructed correction value. Therefore, the convergence of swingback is performed quickly.

When a predetermined time T sufficient for convergence of the swing-back has passed (FIG. 5), the microcomputer 25 resets the swing-back flag, and all the flags are reset.
As a result, the correction value is not instructed, and the microcomputer 25 returns the spring constant and the damping force to the original small values, and returns to the suspension state during normal running.

As described above, according to this embodiment, not only the swing due to the individual traveling situations is suppressed but also the swing caused by the overlapping of the traveling situations is promptly corrected by the combined correction value. Can be suppressed.

In the present embodiment, the microcomputer 25 determines the traveling condition by the above-mentioned sensors, but it goes without saying that the driver may perform all or part of the operation.

Further, in this embodiment, the maximum value is selected when the correction values are combined, but when the correction value is changed by switching between two values, for example, the larger correction value is selected. The logical value may be taken as the logical value "1" and the smaller correction value is taken as the logical value "0", and the logical sums thereof may be taken when synthesizing the correction values, which is, of course, equivalent to the above-described maximum value calculation. is there.

Further, since the combination of oscillations to be superposed is finite, the maximum value is calculated for each combination of the correction values, and the result is stored in the microcomputer 25 to superimpose the oscillations. Correspondingly, the stored maximum value may be read.

[0048]

As described above, according to the present invention, when the swings are superposed during traveling, the spring constant and the damping force are promptly controlled in accordance with the combination of the swings. The swing can be effectively and quickly 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 of the steering wheel.

[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 an operation flowchart of this embodiment.

FIG. 4 is a diagram showing a correspondence between a traveling state and a correction value.

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

FIG. 6 is a diagram showing an example of a combined correction value according to the present embodiment.

FIG. 7 is a diagram showing an example of a conventional suspension device.

FIG. 8 is a conventional operation timing chart.

[Explanation of symbols]

 1, 13a to 13d Air spring 2, 16a to 16d Shock absorber 3 Swing suppression means 4 Indication means 11 Vehicle body 12a to 12d Wheels 14a to 14d Communication valve 15a to 15d Sub tank 17 Mode selection 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) interposed between a vehicle body and a plurality of wheels, and having a spring constant that can be increased and decreased; and an air spring (1) interposed between the vehicle body and the plurality of wheels, respectively.
In addition, 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 swing due to running conditions are instructed, and the spring constant and the correction value are adjusted according to the correction value. In a suspension device for a vehicle, comprising a rocking suppressing means (3) for changing the damping force, a maximum value for each wheel of the correction value for each rocking is set to a maximum value according to a traveling situation in which the rocking overlaps. A suspension device for a vehicle, characterized in that an instruction means (4) for instructing to the rocking suppression means (3) is added.