JPH07266826A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To restrict the effect of nose dive and squat on an air suspension vehicle with a low spring constant during moving up and down a slope. CONSTITUTION:An air suspension device is provided with a control device to automatically change over an air spring 2 and a variable shock 7 to be soft or hard. The control device 9 has an inclination sensor 18 and a mode change-over switch 10 in an AUTO position to change over a spring constant and the damping force of the variable shock absorber 7 after receiving a signal from the inclination sensor 18. In this way, the spring constant of front and rear wheels and the damping force of the variable shock absorber are changed over to allow an inclination to be read from the inclination sensor 18 when the mode change-over switch 10 in the control device 9 is in the AUTO position and nose dive and squat to be restricted when the inclination is above a set value, and such operation is continued until the inclination is below the set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air suspension system having a control device for automatically switching an air spring and a variable shock absorber to soft or hard.

[0002]

2. Description of the Related Art Vehicles equipped with conventional air suspensions, especially sightseeing buses, have a low spring constant and a small minimum ground clearance, so that the front side of the vehicle further sinks when moving downhill (nose dive). On the other hand, when climbing uphill, there was a case where the front side and the rear overhang part rubbed on the road surface when traveling while the rear side was more depressed (squat) due to load movement. Further, regarding a control device for an electronically controlled air suspension vehicle, when rolling occurs in the vehicle body due to disturbance in a straight traveling state, the rolling can be suppressed, and as a conventional technique for improving the riding comfort, a control system block diagram is shown in FIG. Kaihei 5-1
No. 93324 is known.

[0003]

However, even with the above technique, the posture control at the time of descending / climbing cannot be appropriately performed. Therefore, it is an object of the present invention to suppress the influence of nose dives and squats when descending or climbing an air suspension vehicle having a low spring constant.

[0004]

According to the present invention, there is provided an air suspension device having a control device for automatically and softly switching an air spring and a variable shock absorber, the air suspension device having a tilt angle sensor, and the mode changeover switch. Has an automatic position, and receives a signal from the tilt angle sensor, and has a controller for switching the spring constant and the damping force of the variable shock absorber. The tilt angle from the sensor is read, and the spring constants of the front and rear wheels and the damping force of the variable shock absorber are switched to suppress the nose dive and squat when this tilt angle is greater than the set value. It has a function that is performed until the following.

Further, according to the present invention, when the tilt angle is positive, the control device sets the air spring of the front shaft to be soft and the air spring of the rear shaft to be hard, and the shock absorber of the front shaft is soft and the shock absorber of the rear shaft is soft. It has a function to be hard.

Further, according to the present invention, when the tilt angle is negative, the control device sets the front air spring to be hard and the rear air spring to be soft so that the front shock absorber is hard and the rear shock absorber is hard. It has the function of softening.

Further, according to the present invention, the control device has a delay timer, and has a function of softening all the air springs and softening all shock absorbers after a lapse of a certain time after the inclination angle becomes equal to or less than the set value. is doing.

[0008]

As described above, according to the present invention, in the air suspension vehicle having a low spring constant, the control device receives signals from the inclination angle sensor to properly adjust the spring constants of the front and rear wheels and the damping force of the variable shock absorber. By controlling it, it is possible to suppress the effects of nose dives and squats when descending and climbing.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, air springs 2a and 2b and variable shock absorbers 7a and 7b are provided between the front axle left and right wheels 1a and 1b and a vehicle body (not shown). Air springs 2c, 2e; 2 are provided between the left and right rear axle wheels 1c, 1d and the vehicle body.
d, 2f and variable shock absorbers 7c, 7e; 7d,
7f is provided. It should be noted that one wheel does not necessarily require two sets of air springs and shock absorbers.

The front axle air springs 2a and 2b communicate with the reservoir tank 3 through leveling valves 4a and 4b to supply and exhaust air, and the rear axle air springs 2c and 2b.
e; 2d and 2f are the leveling valve 4c, the communication valve 8a,
Air is supplied and exhausted by connecting to the reservoir tank 3 via 8b. Also, the air springs 2a, 2b, 2c, 2
e; 2d, 2f are switching valves 6a, 6b, 6c, 6e; 6
Connected to the sub-tanks 5a, 5b, 5c, 5d via d, 6f, and the switching valves 6a, 6b, 6c, 6e; 6d, 6
When f is opened, the air springs 2a, 2b, 2c, 2e;
2d and 2f communicate with the sub tanks 5a, 5b, 5c and 5d, and the capacity as an air spring increases, so that the characteristics of the air springs 2a, 2b, 2c, 2e; 2d and 2f can be made soft. When closed, the switching valve 6a,
When 6b, 6c, 6e; 6d, 6f are opened, the air springs 2a, 2b, 2c, 2e; 2d, 2f and the sub tanks 5a, 5b, 5c, 5d are cut off from the flow passages, so that the capacity as an air spring. And the spring constant can be switched to a hard one.

Further, the switching valves 6a, 6b, 6c, 6
e; 6d, 6f, the variable shock absorbers 7a, 7
b, 7c, 7e; 7d, 7f are based on input information from the steering angle sensor 11, the brake lamp switch 12, the parking brake switch 13, the lateral acceleration sensor 14, the vertical acceleration sensor 15, the backup lamp switch 16, and the vehicle speed sensor 17. Further, the spring constant of the air spring and the damping force characteristic of the variable shock absorber can be switched between two levels, soft and hard, by a control signal from the control unit 9.

FIG. 2 is a configuration diagram of one wheel including a tire 1, an air spring 2, a leveling valve 4, a sub tank 5, a switching valve 6, and a variable shock absorber 7. FIG. 3 is a mode switching switch 10 and a tilt angle sensor. It is a control system block diagram which consists of 18, the spring constant switching valve 6, and the variable shock absorber 7.

Next, the control flow will be described with reference to FIG.
Referring also to FIG. 1, first of all, the mode selector switch 10 is set to automatic (step 1), the tilt angle θ is read in step 2, and the absolute value of the tilt angle | θ |
Is equal to or greater than a certain amount θ0. If the value is less than a certain amount θ0, repeat step 3. If it is equal to or more than a certain amount θ0, the process proceeds to step 4, and it is determined whether or not the inclination angle is positive, and if it is positive, that is, if the vehicle is descending backward, it is determined to be squat, and the spring constant switching valve 6a of the front springs 2a and 2b is determined. , 6b are closed (step 5), the spring constant switching valves 6c, 6e; 6d, 6f of the rear springs 2c, 2e; 2d, 2f are opened (step 6), and the front side variable shock absorbers 7a, 7b are made soft ( Step 7), rear variable shock absorber 7
c, 7e; 7d, 7f are hard.

If it is negative, that is, if it falls to the front, it is judged to be a nose dive, and the spring constant switching valve 6 of the front springs 2a and 2b is determined.
a and 6b are closed (step 9), rear springs 2c and 2e;
2d and 2f spring constant switching valves 6c, 6e; 6d, 6f are opened (step 10), front side variable shock absorbers 7a, 7b are made hard (step 11), rear side variable shock absorbers 7c, 7e; 7d, 7f. Is software (step 12).

When step 8 or step 12 is completed, the routine proceeds to step 13, where it is judged whether or not the absolute value of the inclination angle | θ | is less than a certain amount θ0, and if it is more than the certain amount θ0, step 13 is repeated. If the absolute value of the inclination angle | θ | is less than the fixed amount θ0, the process proceeds to step 14, the delay timer is started, and in step 15, it is determined whether the absolute value of the inclination angle | θ | is less than the fixed amount θ0. When the value is equal to or greater than the certain amount θ0, the process returns to step 13 and steps 13 to 15 are repeated.

If the absolute value of the inclination angle | θ | is less than the fixed amount θ0, the process proceeds to step 16, and it is judged whether or not the timer set time has elapsed. If not, step 15
Returning to step 17, if the time has elapsed, the process proceeds to step 17, and the spring constant switching valves 6a, 6b, 6c, 6e; 6d, 6f of all wheels are opened, and the variable shock absorbers 7a, 7b, 7 of all wheels are opened.
c, 7e; 7d, 7f are softened, and the control ends.

[0017]

As described above, according to the present invention, as described above, in the present invention, in the air suspension vehicle having a low spring constant, the control device receives the signal from the inclination angle sensor and the springs of the front and rear wheels. By properly controlling the constant and the damping force of the variable shock absorber, it is possible to suppress the effects of nose dives and squats when descending or climbing.

[Brief description of drawings]

FIG. 1 is an overall system configuration diagram of an embodiment.

FIG. 2 is a configuration diagram of one wheel according to an embodiment.

FIG. 3 is a block diagram of a control system according to an embodiment.

FIG. 4 is a control flowchart of the present invention.

FIG. 5 is a block diagram of a conventional control system.

[Explanation of symbols]

1, 1a, 1b, 1c, 1d ... Wheel 2, 2a, 2b, 2c, 2d, 2e, 2f ... Air spring 3 ... Reservoir tank 4, 4a, 4b, 4c ... Leveling valve 5 5a, 5b, 5c, 5d ... Sub tank 6, 6a, 6b, 6c, 6d, 6e, 6f ... Spring constant switching valve 7, 7a, 7b, 7c, 7d, 7e, 7f ... Variable shock Absorber 9 ... Control unit 10 ... Mode change switch 18 ... Inclination angle sensor

Claims (4)

[Claims] 1. An air suspension device having a control device for automatically and softly switching an air spring and a variable shock absorber, comprising an inclination angle sensor, wherein the mode changeover switch is in an automatic position, and an inclination angle. Receiving the signal from the sensor, the spring constant,
And a controller for switching the damping force of the variable shock absorber, the controller reading the inclination angle from the inclination angle sensor when the mode changeover switch is in the auto mode, and when the inclination angle is equal to or greater than the set value, the nose dive and the squat are read. The air suspension device is characterized in that the spring constants of the front and rear wheels and the damping force of the variable shock absorber are switched so as to suppress the operation, and the operation is performed until the inclination angle becomes equal to or less than a set value. 2. When the tilt angle is positive, the control device sets the front air spring to be soft, the rear shaft air spring to be hard, the front shaft shock absorber to be soft, and the rear shaft shock absorber to be hard. The air suspension device according to claim 1, which has a function to perform. 3. When the tilt angle is negative, the control device sets the front air spring to be hard, the rear shaft air spring to be soft, the front shaft shock absorber to be hard, and the rear shaft shock absorber to be soft. The air suspension device according to claim 1, which has a function to perform. 4. The control device has a delay timer, and has a function of softening all the air springs and softening all shock absorbers after a lapse of a fixed time after the inclination angle becomes equal to or less than a set value. Air suspension device.