JPH0899519A - Air suspension device for vehicle - Google Patents

Abstract

PURPOSE: To effectively restrict angle displacement so as to improve maneuverability even in sudden change in a vehicle by changing a supply/discharge neutral point of a mechanical leveling valve so as to heighten the car height in a load moving side based on behavior related to sprung rolling or pitching direction. CONSTITUTION: An air spring 2 and a shock absorber 7 are provided between a car body 20 and a tire 1, and a leveling valve 4 is interposed between the air spring 2 and an air reservoir tank 25 so that a rod 32 having an extension/ contraction mechanism 35 is interposed between a free end side of an operation lever 31 and an axle side member 33. Signals from sprung rolling and pitching angle detection sensors 41, 42 are input into a control unit 9, the extension/ contraction mechanism 35 is controlled by a rack pinion and a step motor so as to heighten the car height of a moving side, the rod 32 is extended/ contracted so as to change a supply/discharge neutral point of the leveling valve 4. Excessive sinking by moving of sprung load is thus prevented and dynamic angle displacement of the vehicle is restricted so that maneuverability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air suspension system, and more particularly to a technique for damping vehicle body vibrations when vehicle behavior changes.

[0002]

2. Description of the Related Art Conventionally, suspensions mounted on buses, large trucks, etc. are, for example, Japanese Utility Model Laid-Open No. 64-52920.
Air suspension devices for vehicles, which support the vehicle body by utilizing air elasticity as disclosed in Japanese Laid-Open Patent Publication No. 2-141510 and Japanese Utility Model Laid-Open No. 2-141510, have become mainstream. Here, since the air suspension device for a vehicle uses the air (air) which is a compressible fluid for the air spring, it is possible to secure a superior riding comfort as compared with a normal one using a leaf spring. .

In the case of using such an air suspension device, the spring constant of the air spring can be adjusted by adjusting the air pressure in the air spring, so that the ride comfort of the vehicle is not reduced. Attempts have been made to improve roll controllability. That is,
As shown in FIG. 7, an air spring 83 is interposed between the vehicle body 81 and the axle 82. And the air spring 83
By providing a sub-tank 86 communicating with the inside through a pipe 85, the pipe 85 is provided with an electromagnetic valve 87 as an opening / closing means, and by controlling the opening / closing of the electromagnetic valve 87 according to the vehicle speed and the steering angle,
Air suspension devices that switch the spring constant have been proposed. Further, a mechanical leveling valve 93 is installed in the pipe 92 that connects the air supply source 91 and the inside of the air spring 83.
The air from the air supply source 91 is supplied and discharged by the mechanical leveling valve 93.

The mechanical leveling valve 93 is provided with a single operating lever 94. When the lever 94 rotates, for example, clockwise, compressed air is discharged from the inside of the air spring 83, and when it rotates counterclockwise. It is being supplied. The rod 95 is used to rotate the operating lever 94.
Is provided, and its upper end is on the free end side of the operating lever 94.
The lower ends are pivotally attached to the free ends of the axle-side members 96, respectively.

Accordingly, the upward displacement Z1 of the vehicle body 81
And a displacement Z0 on the axle side occurs, for example, when the vehicle height increases with Z1-Z0> 0, the rod 95 is pivotally mounted between the operation lever 94 and the member 96. The operating lever 94 rotates clockwise and the air spring 83
Mechanical leveling valve to exhaust the air inside
Control 93. On the contrary, when the vehicle height decreases, compressed air is supplied to the air spring 83 via the valve 93. Therefore, the vehicle height is always returned to the predetermined height.

Further, for example, when the vehicle speed is less than a predetermined value, or when the vehicle speed is more than the predetermined value but the steering angle is less than the predetermined value, the solenoid valve 87 is opened and the inside of the air spring 83 and the sub tank 86 are integrated, The air volume inside the air spring 83 is substantially increased. In this case, as the air volume is larger, the internal pressure does not increase with respect to the external force, so that the reaction force of the air spring 83 becomes smaller and the spring constant becomes smaller, so that 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 87 is closed to shut off the inside of the air spring 83 from the sub tank 86, thereby substantially reducing the air volume inside the air spring 83. Make it smaller. In this case, the reaction force of the air spring 83 is increased, the spring constant is increased, and the roll can be reduced. As an air suspension device in which the spring constant is switched as described above, in order to detect the rolling motion of the vehicle body, vertical G sensors are arranged on the left and right outside in the vicinity of the front axle of the vehicle body to detect the rolling motion of the vehicle body. When it detects it, there is one that tries to improve the riding comfort by switching at least one of the air spring or the shock absorber to the hard state to suppress the rolling operation and detect the pitching operation of the vehicle body by the vertical G sensor. In addition, at least one of the air spring and the shock absorber is switched to a hard state to suppress the pitching operation (see Japanese Patent Laid-Open No. 5-193324).

On the other hand, in order to prevent the vehicle body from swinging during loading and unloading of luggage, means for changing the damping force of the shock absorber provided in parallel with the air spring is provided,
When the vehicle speed detected by the vehicle speed detection means or the like is less than or equal to a predetermined vehicle speed, there is a vehicle speed that is almost stopped, and there is one that automatically increases the damping force of the shock absorber and is detected. The damping force of the shock absorber is increased when the vehicle speed is equal to or lower than a predetermined vehicle speed (see Japanese Patent Laid-Open No. 61-269513).

[0009]

By the way, a dynamic angular displacement and a static angular displacement occur in the vehicle body depending on the running state of the vehicle. Here, the dynamic angular displacement is an angular displacement when the vehicle body or the like is displaced when a behavior change occurs. On the other hand, the static angular displacement is an angular displacement after a certain amount of time has passed and convergence, and also affects a dynamic angular displacement when a behavior change occurs.

Here, the dynamic angular displacement can be suppressed by switching the shock absorber to a harder than when the shock absorber is switched to a soft one. For example, the applicant of the present invention detects the pitch angle and the roll angle. However, by changing the suspension characteristics to hard, even if there is a load movement (moment due to gravity) on slopes and slopes, the dynamic pitch angle and roll angle can be made smaller than when the suspension characteristics are soft. I applied for the one that made it possible (Japanese Patent Application No. 6-60418).
issue).

However, the static angular displacement cannot be sufficiently suppressed only by switching the shock absorber to a hard one. Therefore, in the conventional vehicle air suspension device, a large angular displacement (roll angle, pitch angle) may occur during a sudden vehicle behavior change such as a sudden braking. There was fear that the distance between the lower part of the car and the ground would be greatly reduced, and the drivability would be reduced.

Therefore, the present invention has been made in view of the above conventional problems, and effectively suppresses the angular displacement that occurs even when the vehicle undergoes a sudden behavior change,
Therefore, it is an object of the present invention to provide a vehicle air suspension device capable of reducing the total angular displacement and improving the controllability of the vehicle.

[0013]

Therefore, according to the invention of claim 1, at least one air-supporting system is provided between the sprung system of the vehicle and each of the front, rear, left and right unsprung systems. A spring, at least one shock absorber provided between the sprung system and each unsprung system, and an air pipe connecting the air spring and an air supply source for supplying air to the air spring. The mechanical leveling valve is provided, and when the mechanical leveling valve deviates from the supply / discharge neutral point due to a change in vehicle height, air is supplied to and discharged from the air spring so that the vehicle height can be returned to the original height. In a vehicle air suspension device in use, a rolling direction behavior detecting means for detecting a behavior of the sprung system in the rolling direction and a pitching direction of the sprung system are provided. Pitching direction behavior detecting means for detecting the behavior, and based on the behavior in the rolling direction of the sprung system detected by the rolling direction behavior detecting means or the behavior in the pitching direction of the sprung system detected by the pitching direction behavior detecting means And a discharge / supply neutral point changing means for changing the supply / discharge neutral point of the mechanical leveling valve so that the vehicle height on the load moving side becomes higher.

Further, according to a second aspect of the invention, at least one air spring is provided between the sprung system of the vehicle and the unsprung systems on the front, rear, left and right, and the sprung system, and the sprung system. And at least one shock absorber provided between each of the unsprung systems, and a mechanical leveling valve interposed in an air pipe connecting the air spring and an air supply source for supplying air to the air spring. In the vehicle air suspension device, wherein when the vehicle height changes, the mechanical leveling valve is opened / closed by a rod having one end connected to the unsprung system so that the vehicle height can be returned to the original height. The rod is configured to extend and contract, the rolling direction behavior detecting means for detecting the behavior of the sprung system in the rolling direction, and the sprung system pitch. Pitching direction behavior detection means for detecting behavior related to the direction, and behavior related to the rolling direction of the sprung system detected by the rolling direction behavior detection means or related to the pitching direction of the sprung system detected by the pitching direction behavior detection means An expansion / contraction amount control means for controlling the expansion / contraction amount of the rod so as to increase the vehicle height on the load moving side based on the behavior is provided.

[0015]

As a function according to the invention described in claim 1, the load moving side is determined based on the behavior of the sprung system which is a rolling angle in the rolling direction or the behavior of the sprung system which is a pitching angle in the pitching direction. The supply / discharge neutral point of the mechanical leveling valve is changed so that the vehicle height of becomes higher.

That is, for example, when the sprung system rolls to the right, the load on the sprung system moves to the right. Furthermore, in this case, the behavior related to the rolling direction of the predetermined code is detected,
Based on the behavior in the rolling direction, the supply / discharge neutral point of the mechanical leveling valve is changed so that the vehicle height on the right side becomes higher and the vehicle height on the opposite left side becomes lower.

Here, since the behavior of the sprung system in the rolling direction or the behavior in the pitching direction occurs not only in abrupt steering and braking operations but also on a downhill road, etc., the spring is changed by changing the neutral point. Excessive depression of the sprung system due to load movement of the upper system is prevented, and inclination of the sprung system with respect to the horizontal direction is suppressed. As the operation according to the invention of claim 2, the vehicle height on the load moving side is based on the behavior of the sprung system which is a rolling angle in the rolling direction or the behavior of the sprung system which is a pitching angle in the pitching direction. The amount of expansion and contraction of the rod that opens and closes the mechanical leveling valve is changed so as to increase, and the same operation as the operation according to the invention described in claim 1 is achieved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an air suspension device for one wheel of a vehicle. That is, in this figure, an air spring 2 and a shock absorber 7 incorporating a damping force switching mechanism are provided between a vehicle body 20 as an unsprung body of a vehicle and a tire 1 as an unsprung body. A communication passage 22 is provided between the inside of the air spring 2 and the sub tank 5 via a spring constant switching valve 6 which is an electromagnetic valve for switching the spring constant.
Is communicated by.

Further, the air reservoir tank 25 for storing compressed air and the air spring 2 are provided by a supply / exhaust passage 21 having a leveling valve 4 for supplying and discharging compressed air to and from the air spring 2. Communicated.
Further, a mechanical leveling valve 4 is provided in a pipe 21 that connects the air reservoir tank 25, which stores compressed air, and the inside of the air spring 2 to the air reservoir tank 25.
The air from is supplied to and discharged from the mechanical leveling valve 4.

The mechanical leveling valve 4 is provided with a single operating lever 31. When this lever 31 rotates, for example, clockwise, compressed air is discharged from the inside of the air spring 2 and when it rotates counterclockwise. It is being supplied. The rod 32 is used to rotate the operating lever 31.
Is provided, and its upper end a is pivotally attached to the free end side of the operating lever 31, and its lower end b is pivotally attached to the free end side of the axle-side member 33.

Further, as a structure according to the present invention, a rod
An extension / contraction mechanism 35 for interposing the rod 32 to be extendable / contractible is interposed in the rod 32 so that the entire length of the rod 32 is variable. As the expansion / contraction mechanism 35, as shown in FIG. 2, a casing 36 whose lower end portion forms a lower rod 34, and the casing 36
A rack 38 that moves in the pinion 37 while meshing with the pinion 37, and the upper end portion forms the upper rod 33;
And a step motor 39 for rotating the.

When the entire length of the rod 32 is changed by the extension / contraction mechanism 35, the neutral point of the operating lever 31 in the rotating direction is changed. That is, the rod 32 and the expansion / contraction mechanism 35 of the rod 32 constitute a supply / discharge neutral point changing means for changing the supply / discharge neutral point of the mechanical leveling valve 4. Further, at the center of gravity position of the vehicle (not shown), a rolling angle detection sensor 41 as rolling direction behavior detecting means for detecting a rolling angle as behavior related to the rolling direction of the sprung system, and a behavior related to the pitching direction of the sprung system. Is provided with a pitching angle detection sensor 42 as a pitching direction behavior detecting means for detecting the pitching angle.

An outline of the rolling angle detection sensor 41 and the pitching angle detection sensor 42 will be described. As shown in FIG. 3, a pivot 44 is projectingly provided in the casing 43, and an arm 46 having a weight 45 at its lower end is pivotally supported by the pivot. The arm 46 is urged and fixed by a center spring 47 along the direction of gravity, and the inclination angle is detected by a potentiometer 48 when the casing 43 is inclined.

Further, the control unit 9 having a built-in microcomputer is provided with a switching M signal from a mode switch 10 to be described later and a rolling angle detection sensor 41.
The rolling angle φ signal detected by and the pitching angle θ signal detected by the pitching angle detection sensor 42 are input. Then, based on the rolling angle φ signal and the pitching angle θ signal, the control unit 9 expands and contracts so as to increase the vehicle height on the moving side.
The expansion / contraction amount control means for controlling 35 and the switching control means for switching between the air spring 2 and the shock absorber 7 are provided by software, and a step motor 39 for moving the rack 38 and the spring constant switching valve 6 are provided. And the actuator 8 of the damping force switching mechanism of the shock absorber 7.
Is controlled by a control signal output from the control unit 9 having a built-in microcomputer, and the expansion / contraction control of the entire length of the rod 32, the opening / closing control of the communication passage 22, and the damping force switching control of the shock absorber 7 are performed. .

FIG. 4 is a detailed control block diagram of an embodiment according to the present invention, in which the changeover M signal output from the mode changeover switch 10 is transmitted via the mode signal input means 51.
The rolling angle φ signal detected by the rolling angle detection sensor 41 is passed through the rolling angle signal input means 52 and the low pass filter 53, and the pitching angle θ signal detected by the pitching angle detection sensor 42 is the pitching angle signal input means 54. And is input to the control means 56 via the low-pass filter 55.

The control signal output from the control means 56 is applied to the spring constant switching valve 6 via the spring constant switching valve switching signal output means 57 and to the damping force of the shock absorber 7 via the shock absorber switching signal output means 58. The stepping motor 39 of the expansion / contraction mechanism 35 is connected to the actuator 8 of the switching mechanism via the leveling valve drive rod expansion / contraction signal output means 59.
Are input respectively.

Next, the control content according to this embodiment will be described. The flow chart shown in FIG. 5 shows the expansion / contraction control of the expansion / contraction mechanism 35 and the switching control contents of the spring constant switching valve 6 and the actuator 8 of the damping force switching mechanism of the shock absorber 7 by the control unit 9.
It is executed only when 10 switching positions are switched to the auto mode.

In step 1 (abbreviated as S1 in the drawing; the same applies hereinafter), the pitching angle θ signal is read from the pitching angle detection sensor 42 through the low pass filter 55. The vehicle has pitching in which the front side of the vehicle lowers and pitching in which the rear side of the vehicle lowers. Therefore, the pitching angle θ signal is a signal having positive and negative signs. In the present embodiment, the pitching with which the front side of the vehicle is lowered is positive, and the pitching with which the rear side of the vehicle is lowered is negative.

By way of the low-pass filter 55, noise countermeasures are taken, and by cutting high frequency signals, frequent control is prevented. In step 2, it is judged whether or not the absolute value | θ | of the pitching angle θ is equal to or more than a predetermined value θ _REF , and the process proceeds to step 3 only when | θ | ≧ θ _REF . In step 3, referring to a map stored in advance, based on the pitching angle θ signal, the expansion / contraction amount δ _FR of the rod 32 of the expansion / contraction mechanism 35 of the front wheel of the vehicle and the expansion / contraction mechanism 35 of the rear wheel of the vehicle. The expansion / contraction amount Δ _RR of the rod 32 is calculated.

The map according to step 3 will be described. In the map, the characteristic line is a characteristic line showing the relationship between the expansion / contraction amount δ _FR related to the front wheels of the vehicle and the pitching angle θ signal, and the front side of the vehicle is lowered. And the pitching angle θ signal is detected as θ> 0, and at this time δ _FR > 0 the expansion / contraction amount δ
_{When FR} is calculated and the rear side of the vehicle goes down, pitching angle θ
The signal is detected as θ <0, and at this time, the expansion / contraction amount δ _FR where δ _FR <0 is calculated. Here, when δ _FR > 0, the rod 32 expands, so that the rod 32 moves upward and the operating lever 31 of the mechanical leveling valve 4 is rotated counterclockwise, so that compressed air enters the air spring 2. It supplies and acts to increase the vehicle height on the front wheel side of the vehicle.
Further, when δ _FR <0, the rod 32 contracts, so that the rod 32 moves downward and the operation lever 31 of the mechanical leveling valve 4 is rotated clockwise, and the compressed air is discharged from the inside of the air spring 2. , It acts to lower the vehicle height on the front wheel side of the vehicle.

On the other hand, the characteristic line is a characteristic line showing the relationship between the amount of expansion / contraction δ _RR of the rear wheel of the vehicle and the pitching angle θ signal. When the rear side of the vehicle is lowered, the pitching angle θ signal becomes θ <.
0, and at this time, the expansion / contraction amount δ _{RR of} δ _RR > 0 is calculated, and when the front side of the vehicle is lowered, the pitching angle θ signal is detected as θ> 0. At this time, the expansion / contraction amount δ _{RR of} δ _RR <0 is obtained. Is calculated. Here, when δ _RR > 0, the rod 32
As the rod 32 moves upward, the operating lever 31 of the mechanical leveling valve 4 is rotated counterclockwise, so that compressed air is supplied into the air spring 2 and the vehicle height on the rear wheel side of the vehicle is increased. Acts to raise. Further, when δ _RR <0, the rod 32 contracts, so that the rod 32 moves downward and the operation lever 31 of the mechanical leveling valve 4 is rotated clockwise, so that compressed air is discharged from the inside of the air spring 2. , And acts to lower the vehicle height on the rear wheel side of the vehicle (see FIG. 6A).

Further, the predetermined value θ used in the determination in step 2
_REF is shown in the map related to step 3, and when the detected pitching angle θ signal is small, the expansion / contraction amount δ of the rod 32 of the expansion / contraction mechanism 35 is set to 0, and a so-called dead zone in which the vehicle height control by the mechanical leveling valve 4 is not performed is performed. It is provided. In step 2, | θ | <θ
When it is determined to be _REF , the flag F is set to F = 1 in step 4, and then the process proceeds to step 5.

Next, at step 5, the rolling angle φ signal is read from the rolling angle detection sensor 41 through the low pass filter 53. The vehicle has a rolling in which the right side of the vehicle is lowered and a rolling in which the left side of the vehicle is lowered, so that the rolling angle θ signal is a signal having positive and negative signs. Further, in the present embodiment, the rolling in which the right side of the vehicle is lowered is positive, and the rolling in which the left side of the vehicle is lowered is negative.

In step 6, it is judged whether or not the absolute value | φ | of the rolling angle φ is equal to or _larger than a predetermined value φ _REF , and |
Only when φ | ≧ φ _REF , proceed to step 7. In step 7, referring to the map stored in advance, the expansion / contraction mechanism of the wheel on the right side of the vehicle is calculated from the rolling angle φ signal.
Calculates the 35 expansion amount [delta] _LH of deformation amount [delta] _RH and the rod 32 of the telescopic mechanism 35 of the wheels of the left side of the vehicle of the rod 32.

The map relating to step 7 will now be described. In the map, the characteristic line is a characteristic line showing the relationship between the amount of expansion / contraction δ _RH of the wheel on the right side of the vehicle and the rolling angle φ signal. Rolling angle φ
The signal is detected as φ> 0. At this time, the expansion / contraction amount δ _{RH such} that δ _RH > 0 is calculated. When the left side of the vehicle is lowered, the rolling angle φ signal is detected as φ <0, and at this time, δ _RH <0.
The expansion / contraction amount δ _RH is calculated. Here, when δ _RH > 0, the rod 32 expands, so that the rod 32 moves upward and rotates the operating lever 31 of the mechanical leveling valve 4 counterclockwise, thereby compressing air into the air spring 2
It is supplied to the inside and acts to raise the vehicle height on the right side of the vehicle. When δ _RH <0, the rod 32 contracts, so the rod 32
32 moves downward and rotates the operating lever 31 of the mechanical leveling valve 4 in the clockwise direction, so that compressed air is discharged from the inside of the air spring 2 and acts to lower the vehicle height on the right side of the vehicle ( See FIG. 6B).

On the other hand, the characteristic line is a characteristic line showing the relationship between the expansion / contraction amount δ _LH of the left wheel of the vehicle and the rolling angle φ signal. When the left side of the vehicle is lowered, the rolling angle φ signal is detected as φ <0. At this time, the expansion / contraction amount δ _{LH of} δ _LH > 0 is calculated, and when the right side of the vehicle is lowered, the rolling angle φ signal is detected as φ> 0. At this time, the expansion / contraction amount δ _{LH of} δ _LH <0 is calculated. . Here, when δ _LH > 0, the rod 32 extends, so that the rod 32 moves upward, and the operating lever 31 of the mechanical leveling valve 4 is rotated counterclockwise, so that compressed air is introduced into the air spring 2. It acts to supply and raise the vehicle height on the left side of the vehicle.
Further, when δ _LH <0, the rod 32 contracts, so that the rod 32 moves downward and the operating lever 31 of the mechanical leveling valve 4 is rotated clockwise, so that compressed air is discharged from the inside of the air spring 2. , It acts to lower the vehicle height on the left side of the vehicle.

The predetermined value φ used in the determination in step 6
_REF is shown in the map relating to step 7, and when the detected rolling angle φ signal is small, the expansion / contraction amount δ of the rod 32 of the expansion / contraction mechanism 35 is set to 0, and a so-called dead zone is provided. In step 6, | φ | <φ
When it is judged to be _REF, it is judged at step 8 whether or not the flag F is F = 1, and when it is judged that F ≠ 1, the routine jumps from step 7 to step 9. If it is determined that F = 1, the pitching angle is small and the rolling angle is small.
Continue below.

In step 9, the expansion / contraction amount δ _FR of the rod 32 of the expansion / contraction mechanism 35 for the vehicle front wheel calculated in step 3 above.
And the expansion / contraction amount δ of the rod 32 of the expansion / contraction mechanism 35 for the vehicle rear wheel.
_RR and expansion / contraction mechanism for the wheels on the right side of the vehicle calculated in step 6
The expansion / contraction amount δ _RH of the rod 32 of the vehicle 35 and the expansion / contraction amount δ _LH of the rod 32 of the expansion / contraction mechanism 35 for the wheels on the left side of the vehicle are calculated as shown in the following equation. .

Here, the amount of expansion and contraction on the right side of the vehicle front side is δ
_FR-RH , the amount of expansion on the left side of the vehicle is δ _{FR -LH} , the amount of expansion on the right side of the vehicle is δ _RR-RH , and the amount of expansion on the left side of the vehicle is δ _RR-LH . δ _FR-RH = δ _FR + δ _RH δ _FR-LH = δ _FR + δ _LH δ _RR-RH = δ _RR + δ _RH δ _RR-LH = δ _RR + δ _{LH In} step 10, the expansion / contraction mechanism of each wheel is calculated. The expansion amount δ of the rod 32 of 35 is output to the step motor 39 of each expansion mechanism 35, and the entire length of the rod 32 of each mechanical leveling valve 4 is expanded and contracted.

In step 11, the spring constant switching valve 6 is closed to switch the spring constant to a large value, and the air spring 2 is set to the hard condition. In step 12, the actuator 8 of the damping force switching mechanism of the shock absorber 7 is switched and controlled, and the shock absorber 7 is switched to the hard type (large damping force). On the other hand, in step 13, since the expansion / contraction amount δ of the rod 32 of the expansion / contraction mechanism 35 for each wheel is δ = 0, each expansion / contraction mechanism 35
No output value is output to the step motor 39, and the entire length of the rod 32 of each mechanical leveling valve 4 is maintained as it is.

Then, in step 14, the spring constant switching valve 6 is opened to switch the spring constant to a small value to set the air spring 2 to be soft, and in step 15, the actuator 8 of the damping force switching mechanism of the shock absorber 7 is set. Is controlled to switch the shock absorber 7 to soft (small damping force) to secure the riding comfort.

Therefore, in the vehicle air suspension device of the present invention, a large angular displacement (roll angle, pitch angle) is initially caused at the time of a sudden vehicle behavior change such as a sudden braking.
Even if occurs, the rod 32 of the expansion / contraction mechanism 35 of each wheel is set so as to cancel the vertical displacement of the vehicle height caused by the angular displacement.
Is calculated, the entire length of the rod 32 of each mechanical leveling valve 4 is expanded and contracted, and when the control is performed, the suspension characteristics are also hardened, so when the vehicle undergoes a sudden behavior change. Also, the distance between the lower part of the vehicle body and the ground can be maintained, and for example, the lower part of the vehicle body can be prevented from contacting the ground.

Therefore, in this embodiment, the generated dynamic and static angular displacements are effectively damped, and the total angular displacement is reduced, so that the steering stability of the vehicle can be improved. There is an effect that. In this example,
The front side of the vehicle controls the right side extension amount, the front side of the vehicle controls the left side extension amount, the rear side of the vehicle controls the right side extension amount, and the rear side of the vehicle controls the left side extension amount. It is needless to say that the same control may be performed only on a predetermined portion without performing all, and further, the extension amount may be controlled instead of the extension amount control for each control. .

Further, by increasing the sensitivity of reading the pitching angle θ signal by the pitching angle detection sensor 42 or the sensitivity of reading the rolling angle φ signal by the rolling angle detection sensor 41, it becomes possible to cope with smaller behavior. More positive attitude control is possible. Also, the pitching angle or rolling angle is always 0.
By performing the feedback control so that, the attitude control can be performed more positively.

Further, in this embodiment, the feeding / discharging neutral point changing means is provided with an expanding / contracting mechanism 35 for varying the entire length of the rod 32, and a step motor 39 is used to set the feeding / discharging neutral point of the mechanical leveling valve 4. Although it is configured by changing, the length of the entire rod 32 is fixed, the mechanical leveling valve 4 itself is rotatably held, and the mechanical leveling valve 4 is turned to change the supply / discharge neutral point. You may go.

Further, in this embodiment, the rolling angle is used as the behavior related to the rolling direction of the sprung system, and the pitching angle is used as the behavior related to the pitching direction of the sprung system, and the rolling angle is used as a sensor for detecting each. Although the sensor 41 and the pitching angle detection sensor 42 are provided, the behavior may be acceleration, and the acceleration can be detected by using an acceleration sensor.

By using the acceleration sensor,
It becomes possible to perform control with better control responsiveness.

[0048]

As described above, according to the first aspect of the invention, the vehicle height on the load moving side is determined based on the behavior of the sprung system in the rolling direction or the behavior of the sprung system in the pitching direction. Since the neutral point of supply and discharge of the mechanical leveling valve is changed so that the spring height becomes higher, it is possible to prevent excessive subduction of the sprung system due to load movement of the sprung system, and to tilt the sprung system with respect to the horizontal direction. Is suppressed, and even when the vehicle suddenly changes its behavior,
The dynamic angular displacement that occurs is effectively damped, and thus total attitude control is performed, which has the effect of improving the maneuverability of the vehicle.

According to the second aspect of the invention, the rod height is increased so that the vehicle height on the load moving side is increased based on the behavior of the sprung system in the rolling direction or the behavior of the sprung system in the pitching direction. Since the amount of expansion and contraction of the vehicle is controlled, the dynamic angular displacement that occurs is effectively dampened even when the vehicle undergoes a sudden behavior change, and thus total attitude control is performed, and the maneuverability of the vehicle is improved. It has the effect of improving.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view showing a configuration of a rod expanding / contracting mechanism according to the embodiment.

FIG. 3 is a schematic configuration diagram showing a configuration of an inclination sensor according to the embodiment.

FIG. 4 is a control block diagram according to the embodiment.

FIG. 5 is a flowchart illustrating the control contents of the above embodiment.

FIG. 6 is a schematic side view illustrating the operation of the above embodiment.

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

[Explanation of symbols]

 1 Tire 2 Air Spring 4 Mechanical Leveling Valve 5 Sub Tank 6 Spring Constant Switching Valve 7 Shock Absorber 8 Actuator 9 Control Unit 31 Operation Lever 32 Rod 35 Expansion Mechanism 39 Step Motor 41 Rolling Angle Detection Sensor 42 Pitching Angle Detection Sensor

Claims (2)

[Claims] 1. An air spring for supporting at least one sprung system provided between a sprung system of a vehicle and front, rear, left and right unsprung systems; and a sprung system and each unsprung system. At least one shock absorber provided between,
A mechanical leveling valve provided in an air pipe that connects the air spring and an air supply source that supplies air to the air spring is provided, and the mechanical leveling valve deviates from the supply / discharge neutral point due to a change in vehicle height. In an air suspension device for a vehicle in which air is sometimes supplied to and discharged from the air spring so that the vehicle height can be returned to the original height, a rolling direction behavior detecting means for detecting behavior related to the rolling direction of the sprung system. And a pitching direction behavior detecting means for detecting a behavior related to the pitching direction of the sprung system, and a spring direction behavior detecting means for the sprung system detected by the rolling direction behavior detecting means or a spring detected by the pitching direction behavior detecting means. Based on the behavior related to the pitching direction of the upper system, the vehicle height on the load transfer side should be increased The mechanical and supply and discharge the neutral point changing means for changing the supply and discharge the neutral point of the leveling valves, air suspension system for a vehicle, characterized in that a. 2. An air spring for supporting at least one sprung system provided between a sprung system of a vehicle and respective unsprung systems in front, rear, left and right, and the sprung system and each unsprung system. At least one shock absorber provided between,
A mechanical leveling valve provided in an air pipe connecting the air spring and an air supply source for supplying air to the air spring is provided, and when the vehicle height changes, one end is connected to the unsprung system. In a vehicle air suspension device in which the mechanical leveling valve is opened / closed by a rod so that the vehicle height can be returned to the original height, the rod is configured to be extendable and the behavior related to the rolling direction of the sprung system is detected. Rolling direction behavior detecting means, pitching direction behavior detecting means for detecting the behavior related to the pitching direction of the sprung system, and rolling direction behavior or pitching direction behavior detection of the sprung system detected by the rolling direction behavior detecting means Load based on the behavior related to the pitching direction of the sprung system detected by the means. Air suspension system for a vehicle in which the expansion amount control means for controlling the amount of extension of the rod so that the vehicle height increases, characterized in that the provided to the mobile side.