JP2946391B2 - Air suspension system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air suspension device for a vehicle, and more particularly to a roll control technique at the time of steering.

[0002]

2. Description of the Related Art Conventionally, as one of suspensions equipped on a bus or a large truck, for example, Japanese Utility Model Laid-Open No.
2. Description of the Related Art An air suspension device for a vehicle that supports a vehicle body by utilizing air elasticity as disclosed in Japanese Patent Application Laid-Open No. 52920 and Japanese Utility Model Application Laid-Open No. 2-141510 is known.

That is, as shown in FIG. 6, air springs 3A and 3B are installed on both sides of the front side of the vehicle between the sprung and unsprung sides, ie, between the vehicle body and the left and right front axles. Have been. Further, air springs 3C, 3D, 3E, 3F are respectively installed on the left and right between the sprung and unsprung sides of the rear side of the vehicle, that is, between the vehicle body and the left and right rear axles. . Note that, for the sake of simplicity, the following description will be referred to as an air spring 3.

Next, an air system related to the vehicle air suspension device will be described. That is, the air pressurized by the air compressor 11 is supplied to the air dryer 1.
After the water contained in the air is removed by 2, it is stored in the air reservoir tank 13. The pressure in the air reservoir tank 13 is adjusted to a predetermined pressure by the governor 14. The compressed air stored in the air reservoir tank 13 is sent to the air spring 3 via the leveling valve 4 of the air spring 3.

[0005] The leveling valve 4 adjusts the degree of filling of the air springs 3 with the compressed air in accordance with the increase or decrease of the load. When the vehicle height decreases, the leveling valve 4 moves the air reservoir tank 13 and the air springs 3 to each other. When the vehicle height rises, the leveling valve 4 opens to the exhaust side, exhausts the air in each air spring 3 and lowers the vehicle height to a predetermined vehicle height. Adjusted.

In a bus, a truck, or the like equipped with the above-described vehicle air suspension device, the vehicle body swings during traveling. The supply and exhaust of the compressed air in the spring 3 are performed. On the other hand, in recent years, there has been a need to enhance the roll controllability without reducing the riding comfort of the vehicle. For this reason, as shown in FIG. An air suspension device has been proposed in which a solenoid valve 6 is provided, an electromagnetic valve 7 as opening / closing means is interposed in the pipe 5, and the opening / closing of the electromagnetic valve 7 is controlled in accordance with a vehicle speed or a steering angle to switch a spring constant. .

For example, when the vehicle speed is lower than a predetermined value or when the vehicle speed is higher than the predetermined value and the steering angle is lower than the predetermined value, the solenoid valve 7 is opened to integrate the inside of the air spring 3 and the sub-tank 6 so that the air is removed. The air volume inside the spring 3 is increased. In this case, since the internal pressure does not increase in response to an external force as the air volume increases, the air spring 3
, The spring constant is reduced, and the riding comfort can be improved.

On the other hand, when the vehicle speed is equal to or higher than the predetermined value and the steering angle is equal to or higher than the predetermined value, the solenoid valve 7 is closed to shut off the inside of the air spring 3 and the sub tank 6, thereby reducing the air volume inside the air spring 3. . In this case, the reaction force of the air spring 3 increases, thereby increasing the spring constant and reducing the roll. In addition, as an air suspension device that switches the spring constant as described above, the roll of the vehicle body is directly detected by a rolling sensor or the like, and when the roll is detected, the solenoid valve is closed to shut off the inside of the air spring and the sub tank, and the roll is stopped. Is known (see Japanese Utility Model Laid-Open No. 3-204).

[0009]

However, in such a conventional air suspension device, the spring constant is largely changed when a roll is generated, but the leveling valve for adjusting the degree of filling of the air spring 3 with the compressed air is controlled. There is no restriction on supply and exhaust from 4.

For this reason, in the roll increasing process as well as in the roll decreasing process, air is supplied to the air spring on the outer side of the turn, and exhaust is performed on the air spring on the inner side of the turn. When turning is performed in opposite directions, there is a problem that the roll angle in the subsequently generated turning direction becomes large. Therefore,
In view of the above-mentioned conventional problems, the present invention controls the supply and exhaust of the air spring by the leveling valve during the roll reduction process, so that the vehicle turns continuously in opposite directions such as when changing lanes. When performed, the object is to reduce the roll angle in the reciprocal turning direction that subsequently occurs.

[0011]

According to the present invention, an air spring is provided between a sprung portion and an unsprung portion of a vehicle, and the air spring and the air reservoir tank for storing compressed air are connected to each other. An air suspension device for a vehicle which communicates via a leveling valve for supplying and exhausting compressed air to and from an air spring, and which communicates the inside of the air spring and a sub-tank via opening / closing means for switching a spring constant. An opening / closing means for controlling the supply / exhaust of compressed air to / from the air spring is provided in a supply / exhaust passage between the leveling valve and the air spring, while a vehicle speed detecting means, a steering angle detecting means, Steering angular velocity calculating means for calculating a steering angular velocity based on an angle, the vehicle speed, a steering steering angle, and a steering angle And control means for controlling the opening and closing means for the supply and exhaust control the opening and closing means of the spring constant switching based on time, the provided said control means, the vehicle speed is less than the predetermined vehicle speed
When the opening / closing means for switching the spring constant is opened,
While opening and closing the supply / exhaust control opening / closing means,
When the steering angle is larger than the speed, the spring
Close the opening / closing means for switching the constant and set the vehicle speed to the specified vehicle speed.
The steering angles and steering angular velocities in the same steering direction are both large.
In such a case, the opening / closing means for the supply / exhaust control should be closed.
Configured.

[0012]

[0013]

According to the first aspect of the present invention, by controlling each opening / closing means based on the vehicle speed, the steering angle and the steering angular speed, the spring constant is switched according to the condition of the vehicle and the steering state, and the roll is reduced. As a result, the driving stability is improved, the riding comfort is improved, and the supply / exhaust control from the leveling valve for adjusting the degree of filling of the compressed air with the air spring is performed.

That is, when the vehicle speed is lower than the predetermined vehicle speed, no roll occurs, so that the spring constant of the air spring is switched to a small value, and leveling by the leveling valve is performed, so that the riding comfort is improved. Further, when the vehicle speed is equal to or higher than the predetermined vehicle speed and the steering angle is large, a roll is generated. Therefore, the spring constant of the air spring is switched to a large value, so that the suspension device has a large roll reducing effect.

Here, in the process of decreasing the roll angle where both the steering angle and the steering angular velocity in the same steering direction are large, the opening / closing means for supply / exhaust control is closed, for example, the left leveling valve and the exhaust valve in the supply state. When the right leveling valve in the state or the left leveling valve in the exhaust state and the right leveling valve in the air supply state are closed, air supply and exhaust are stopped. As a result, the pressure increase side of the air spring internal pressure addition amount is reduced, and the pressure decrease side is increased. As a result, when the turning is continuously performed in the opposite direction, the roll angle in the subsequently opposite turning direction is reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an air suspension device for one wheel of a vehicle. That is, in this drawing, an air spring 22 and a shock absorber 23 having a built-in damping force switching mechanism are provided between a vehicle body 20 as a sprung portion of the vehicle and a tire 21 as a unsprung portion. An air reservoir tank (not shown) in which compressed air is stored and the air spring 22 are provided with a leveling valve 2 for supplying and exhausting compressed air to and from the air spring 22.
4 are connected by a supply / exhaust passage 25 interposed. In a supply / exhaust passage 25 between the leveling valve 24 and the air spring 22, a supply / exhaust control valve 26 which is an electromagnetic valve as an opening / closing means for controlling supply / exhaust of compressed air to the air spring 22 is interposed. Is done. The inside of the air spring 22 and the sub-tank 27 are connected to a spring constant switching valve 28 comprising an electromagnetic valve as an opening / closing means for switching the spring constant.
Are communicated by a communication passage 29 interposed.

Here, in the present invention , the vehicle speed detecting means, the steering angle detecting means, the steering angular velocity calculating means for calculating the steering angular velocity based on the steering angle, and the vehicle speed, the steering angle and the steering angular velocity are calculated. Control means for controlling the spring constant switching valve 28 and the supply / exhaust control valve 26 based on this. When the vehicle speed is lower than a predetermined vehicle speed, the control means controls the spring constant switching valve 2
8, while opening the supply / exhaust control valve 26,
When the vehicle speed is equal to or higher than a predetermined vehicle speed and the steering angle is large, the spring constant switching valve 28 is closed. When the vehicle speed is equal to or higher than the predetermined vehicle speed and both the steering angle and the steering angular speed in the same steering direction are large, the supply / exhaust control valve is set. 26 was closed.

In this configuration, the spring constant switching valve 28 and the supply / exhaust control valve 26 are controlled to open and close by a control signal output from a control unit 30 containing a microcomputer, and a communication passage 29 and a supply / exhaust passage 25 are provided. Is controlled to perform opening / closing control. The control unit 30 includes a mode changeover switch 3 described later.
Switching signal from 1 and vehicle speed sensor 3 as vehicle speed detecting means
2, a steering angle θ signal from a steering angle sensor 33 provided in a steering (not shown) serving as a steering angle detecting means is input to the control unit 30, and the control unit 30 calculates a steering angular velocity θα based on the steering angle. Means for calculating, based on the mode switching signal, the vehicle speed V, and the steering angle .theta.
Control means for controlling the exhaust control valve 26 is provided as software.

FIG. 2 is a detailed control block diagram. The signal output from the mode changeover switch 31 is input to the control means 35 via the mode signal input means 34. The signal output from the steering angle sensor 33 is input to the control means 35 via the steering angle signal input means 36.
The signal output from the steering angle signal input means 36 is input to a steering angle signal differentiating means 37 as a steering angular velocity calculating means, and the steering angular velocity signal output from the steering angle signal differentiating means 37 is input to the control means 35. You. Further, a signal output from the vehicle speed sensor 32 is input to the control means 35 via the vehicle speed signal input means 38.

The control signal output from the control means 35 is
Via the supply / exhaust control valve switching signal output means 39 to the supply / exhaust control valve 26, via the spring constant switching valve switching signal output means 40 to the spring constant switching valve 28, and via the shock absorber switching signal output means 41. Each is input to the actuator 23A of the damping force switching mechanism of the shock absorber 23.

Next, with reference to the flowchart shown in FIG. 3, the contents of opening / closing control of the spring constant switching valve 28 and the supply / exhaust control valve 26 by the control unit 30 will be described. That is, in step 1 (abbreviated as S1 in the figure, the same applies hereinafter), the switching position of the mode changeover switch 31 is determined, and whether the mode is the hard mode (large spring constant) or the soft mode (small spring constant) (this embodiment) In this case, the software mode is selected. When the soft mode is selected, the process proceeds to step 16, and when the auto mode is selected, the process proceeds to step 2.

If the soft mode is selected, in step 16, the spring constant switching valve 28 is opened to switch the spring constant to a small value, and the process proceeds to step 17 to soften the shock absorber 23 (the spring constant is reduced). Switch. In step 18, the supply / exhaust control valve 26 is opened to perform leveling (supply / exhaust to the air spring 22) by the leveling valve 24.

On the other hand, when the auto mode is selected, in step 2, the vehicle speed signal V from the vehicle speed sensor 32 is read. In step 3, the steering angle signal θ from the steering angle sensor 33 is read. In Step 4, the steering angle θ is calculated by differentiating the steering angle θ. Step 5
In, it determines the vehicle speed V is to or greater than the predetermined vehicle speed V _R. If it is determined that the vehicle speed V is lower than the predetermined vehicle speed V _R , the vehicle is traveling at a low speed and the roll is small, so that the process proceeds to step 16 and subsequent steps similar to the case where the soft mode is selected in step 1. .

[0024] In Step 2 If the vehicle speed V is determined to be equal to or greater than the predetermined vehicle speed V _R, the vehicle is traveling at high speed, there is a fear that the roll occurs, control based on the steering angle of the steering θ Then, the process proceeds to step 6 and subsequent steps.
In step 6, for example, the steering angle of the right steering direction theta is equal to or a predetermined steering angle theta _R above, the steering angle theta is in a predetermined steering angle theta _R above, proceeds to step 7, now Means that the steering angular velocity θα in the right steering direction is equal to the predetermined steering angular velocity θ
determines whether or not alpha _R above, the steering angular velocity .theta..alpha is a predetermined steering angular velocity .theta..alpha _R above, proceeds to step 8,
The spring constant switching valve 28 is closed to change the spring constant to a large value.
Is switched to hard (large spring constant). Step 10
Then, the supply / exhaust control valve 26 is closed and the leveling valve 2 is closed.
4 (supply and supply to air spring 22)
(Exhaust).

[0025] In step 7, when the steering angular velocity .theta..alpha is less than the predetermined steering angular velocity .theta..alpha _R, the routine proceeds to step 11, the shock closes the spring constant switching valve 28, switches the spring constant in a large, the routine proceeds to step 12 Absorber 23
Is switched to hard (large spring constant). Step 13
Then, the supply / exhaust control valve 26 is opened and the leveling by the leveling valve 24 is performed.

On the other hand, if the steering angle θ is smaller than the predetermined steering angle θ _R in step 6, the process proceeds to step 14 to determine whether the steering angle θ in the left steering direction is equal to or smaller than the predetermined steering angle −θ _R. If the steering angle θ is equal to or smaller than the predetermined steering angle −θα _R (the steering angle θ is large), the process proceeds to step 15, and this time,
The steering angular velocity θα in the left steering direction is equal to a predetermined steering angular velocity −θα.
It is determined whether or not the steering angular velocity is less than or equal to _R , and if the steering angular velocity θα is equal to or less than a predetermined steering angular velocity −θα _R (the steering angular velocity θα is large),
Proceeding to step 8 and thereafter, as described above, the spring constants of the air spring 22 and the shock absorber 23 are changed to be large, and the leveling by the leveling valve 24 is stopped, and the supply and exhaust of the air spring 22 are stopped. .

[0027] In step 15, if the steering angular velocity θα exceeds a predetermined steering angular velocity -θα _R (steering angular velocity θα small)
Goes to step 11 and thereafter, as described above, the spring constants of the air spring 22 and the shock absorber 23 are switched to be large, and the leveling by the leveling valve 24 is performed. When the steering angle of the left steering direction θ exceeds a predetermined steering angle - [theta] _R in step 14 (the steering angle θ is small)
Proceeds to step 16 to switch the spring constants of the air spring 22 and the shock absorber 23 to a small value and to perform leveling by the leveling valve 24 as described above.

FIG. 4 shows the steering angle θ and the steering angular velocity θα and the supply / exhaust control valve 26 described in the above flowchart.
6 is a graph clarifying the relationship with the opening / closing state of the vehicle. As apparent from the above description of the flow chart, when the vehicle speed V is lower than the predetermined vehicle speed V _R, since the roll is small, switches the spring constant of the air spring 22 and shock absorber 23 to the small, perform leveling by the leveling valve 24 By doing so, riding comfort is improved.
Further, in the vehicle speed V is higher than a predetermined vehicle speed V _R, when steering angle θ is large, the roll is generated by switching the spring constant of the air spring 22 and shock absorber 23 to the large, effect of reducing rolls is a large It can be a suspension device.

[0029] Here, as apparent from the description of the flowchart, the vehicle speed V is to close the supply and exhaust control valve 26 when the are large predetermined vehicle speed V _R or more and the same steering direction of the steering angle θ and the steering angular velocity θα The operation and effect will be described with reference to the time chart of FIG. This figure shows the steering angle and steering angular velocity, roll angle, the opening / closing state of the supply / exhaust control valve, the opening / closing state of the leveling valve (supply / exhaust state), and the air spring internal pressure addition (only the pressure supplied by the leveling valve). Shows the relationship.

That is, in the process of decreasing the roll angle in FIG. 6B, both the steering angle and the steering angular velocity in the same steering direction are large as shown in FIG. By closing the control valve, for example, as shown in FIG. 3D, for example, a left leveling valve in an air supply state and a right leveling valve in an exhaust state or a left leveling valve in an exhaust state and a right leveling in an air supply state. By closing the valve, air supply and exhaust are stopped. As a result, as shown in FIG. 8E, the pressure increase side of the air spring internal pressure addition amount is reduced, and the pressure decrease side is increased. As a result, as shown in FIG. 3B, when turning is continuously performed in opposite directions, the roll angle in the subsequently opposite turning direction is reduced.

That is, in the roll reduction process, by closing the leveling valve 24, no air is supplied to the air spring 22 outside the turning and no air is exhausted to the air spring 22 inside the turning. When the vehicle turns continuously in opposite directions, such as when changing lanes, it is possible to reduce the roll angle in the subsequent opposite turning direction. In this case, the roll angle can be made smaller than the original roll angle caused by the lateral acceleration.

[0032]

As described above, according to the first aspect of the present invention, each opening / closing means is controlled based on the vehicle speed, the steering angle, and the steering angular speed, so that the vehicle can be controlled according to the situation and the steering state. The spring constant is switched, the roll is reduced and running stability is improved, while riding comfort is improved, and supply / exhaust control from a leveling valve that adjusts the degree of compressed air filling of the air spring is performed. Will be

That is, when the vehicle speed is lower than the predetermined vehicle speed, the spring constant of the air spring can be switched to a small value.
The leveling by the leveling valve can be performed to improve the riding comfort, and when the vehicle speed is equal to or higher than the predetermined vehicle speed and the steering angle is large, the spring constant of the air spring can be switched to a large value, and the roll can be reduced.

Further, in the process of decreasing the roll angle in which the steering angle and the steering angular velocity in the same steering direction are both large, the opening / closing means for supply / exhaust control is closed, so that the vehicle turns continuously in opposite directions. In this case, it is possible to reduce the roll angles in the opposite turning directions that occur subsequently.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a control system diagram of the embodiment.

FIG. 3 is a flowchart illustrating control contents of the embodiment.

FIG. 4 is a graph showing a control pattern according to the embodiment.

FIG. 5 is a time chart illustrating the effect of the embodiment.

FIG. 6 is a system configuration diagram of an example of a conventional vehicle air suspension device.

FIG. 7 is a system configuration diagram of another example of the conventional vehicle air suspension device.

[Explanation of symbols]

 Reference Signs List 20 vehicle body 21 tire 22 air spring 24 leveling valve 25 supply / exhaust passage 26 supply / exhaust control valve 27 sub tank 28 spring constant switching valve 29 communication passage 30 control unit 32 vehicle speed sensor 33 steering angle sensor 35 control means 36 steering angle signal input means 37 Steering angle signal differentiating means 38 Vehicle speed signal input means 39 Supply / exhaust control valve switching signal output means 40 Spring constant switching valve switching signal output means

Claims (1)

(57) [Claims] An air spring is provided between a sprung portion and a unsprung portion of a vehicle, and a leveling valve for supplying and discharging compressed air to and from the air spring and an air reservoir tank storing compressed air. And an exhaust passage between the leveling valve and the air spring, wherein the interior of the air spring communicates with the sub-tank via an opening / closing means for switching a spring constant. A vehicle speed detecting unit, a steering steering angle detecting unit, and a steering angular speed calculating unit that calculates a steering angular speed based on the steering angle while interposing an opening / closing unit for controlling supply and exhaust of compressed air to the air spring. An opening / closing means for switching the spring constant based on the vehicle speed, a steering angle, and a steering angular speed; And control means for controlling the opening and closing means for air control, the provided, said control means, said spring when the vehicle speed is less than the predetermined vehicle speed
Opening and closing means for switching constants, and
While the opening / closing means is open, the vehicle speed is
When the steering angle is large, the spring constant
When the closing means is closed, the vehicle speed is
When both the steering angle and the steering angular velocity in the rudder direction are large,
An air suspension device for a vehicle, wherein an opening / closing means for supply / exhaust control is closed .