JPH0899516A - Air suspension device for vehicle - Google Patents

Abstract

PURPOSE: To perform appropriate rolling control from low to high speed by deciding which one is preceded in steering angle and acceleration controls, by speed for switching an air spring and a shock absorber into hard or soft one by detected steering angle and acceleration. CONSTITUTION: A shock absorber 7 having an air spring 2 and a damping force switch mechanism is provided between a vehicle body 20 and a tire 1, and signals of respective speed, steering, and lateral acceleration sensors 17, 11, 14 are input into the control unit 9. The first and the second switch means for switching the shock absorber 7 and the air spring by the steering angle or the lateral acceleration, and the first and the second selection means for selecting either of the selection means are provided in the control unit 9. And the selection means is changed based on speed so that the control signal is output to the spring constant switch valve 6 and an actuator 8 of the damping force switch mechanism to perform damping force switch control. Therefore appropriate rolling control from low to high speed can be performed.

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 device, and more particularly to a technique for damping vehicle body vibration when rolling occurs in a vehicle.

[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. 6, a sub-tank 86 communicating with the inside of the air spring 83 via a pipe 85 is provided, and a solenoid valve 87 as an opening / closing means is provided in the pipe 85, and a solenoid valve 87 is provided according to a vehicle speed and a steering angle. An air suspension device has been proposed in which the spring constant is switched by controlling the opening and closing of the. Incidentally, 84
Is a leveling valve interposed in a communication pipe with an air reservoir tank (not shown) whose pressure is adjusted to a predetermined pressure.

For example, when the vehicle speed is less than a predetermined value or when the vehicle speed is more than a 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 so that the air The air volume inside the 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 the electronically controlled air suspension device in which the spring constant is switched as described above, in order to detect the rolling motion of the vehicle body, an upper and lower G is provided on the left and right outside near the front axle of the vehicle body.
When a sensor is arranged and at least one of rolling movements of the vehicle body is detected, at least one of the air spring and the shock absorber is switched to a hard state to suppress the rolling movement to improve the riding comfort. 5-193324 publication).

Further, in view of the fact that the vehicle body may roll to the leeward side of the crosswind when the vehicle is traveling, the present applicant considers that the steering angle detected by the steering angle detection means is less than the predetermined angle. Previously proposed an air suspension system for a vehicle having a switching control means for switching the states of the air spring and the shock absorber to hard or soft based on the lateral acceleration detected by the acceleration detecting means (special feature: Wishhei 6-63906
issue).

[0007]

Based on the steering angle detected by the steering angle detecting means and the lateral acceleration detected by the acceleration detecting means, the state of each of the air spring and the shock absorber can be made hard or soft. In the case of having the switching control means for switching control, when the roll control by the steering angle is prioritized over the roll control by the lateral acceleration, it is necessary to detect the steering angle without fail. .

However, when the vehicle speed is high, that is, when the vehicle is traveling at a high speed, the driver hardly steers the vehicle, and the steering angle detected by the steering angle detecting means is small. When the control is performed based on the angle, a high-precision steering angle sensor is required to detect the small steering angle, and further, it is necessary to attach the steering angle sensor with high accuracy, which is technically difficult. Also, there is a fear that the cost will be difficult.

Therefore, the present invention has been made in view of the above conventional problems, and the air spring is based on the steering angle detected by the steering angle detection means and the lateral acceleration detected by the acceleration detection means. And a shock absorber having a switching control means for switching the state of each of the shock absorbers in a hard or soft manner, it is determined in consideration of the vehicle speed which of roll control by steering angle and roll control by lateral acceleration is given priority. A vehicle air suspension device that enables stable posture control by performing appropriate roll control from low speed to high speed without providing a high-precision steering angle sensor, effectively damping the vehicle body vibration that occurs. The purpose is to provide.

[0010]

For this reason, in the invention described in claim 1, at least one sprung system is provided between the sprung system and each of the front, rear, left and right unsprung systems in the vehicle to support the sprung system. In a vehicle air suspension device comprising an air spring and at least one shock absorber provided between each of the sprung systems and each of the unsprung systems, a vehicle speed detecting means for detecting a vehicle speed, and a steering Based on the steering angle detected by the steering angle detection means for detecting the steering angle, the acceleration detection means for detecting the acceleration occurring in the vehicle at least in the lateral direction, and the air spring and the shock absorber respectively. Based on the first switching control means for switching the state to hardware or software and the lateral acceleration detected by the acceleration detecting means, Second switching control means for controlling the states of the spring and the shock absorber by hardware or software, and first selection means for preferentially selecting the first switching control means with respect to the second switching control means. And second selection means for preferentially selecting the second switching control means with respect to the first switching control means, and the first selection means based on the vehicle speed detected by the vehicle speed detection means. And a switching control unit that controls switching of any one of the second selection units.

According to a second aspect of the present invention, the switching control means performs switching control to the first selecting means when the vehicle speed detected by the vehicle speed detecting means is a predetermined value or less, and the vehicle speed is a predetermined value. When it is larger than the above, the second selection means is used for switching control. The invention according to claim 3 is the first
When the steering angle detecting means detects that the steering wheel has been steered to the left, the switching control means of the vehicle turns the air spring on the right side of the vehicle into the hard state, the air spring of the left side into the soft state and the shock absorber to the hard state. When the steering angle detection means detects that the steering wheel has been steered to the right, the air spring on the right side of the vehicle is set to the soft state, the air spring on the left side is set to the hard state, and the shock absorber is set to the hard state. The configuration is such that switching control is performed depending on the state.

According to a fourth aspect of the present invention, the second switching control means controls the states of the air spring and the shock absorber to be hard when the lateral acceleration detected by the acceleration detecting means is a predetermined value or more. The configuration is such that switching control is performed.

[0013]

The rolling of the vehicle body occurs when the inertial force due to the centripetal acceleration generated when the lane is changed or when the vehicle turns is applied to the vehicle body, and when the vehicle receives a sudden crosswind, the crosswind directly affects the vehicle. External force may act. Here, the rolling motion of the vehicle body caused by the action of inertial force due to the centripetal acceleration generated when changing lanes or turning, the steering direction and the rolling motion direction are the same, and in this case, based on the steering angle, By the first switching control means, the respective states of the air spring and the shock absorber are controlled to be switched between hard and soft, whereby proper roll control is performed.

On the other hand, when the vehicle is exposed to a sudden crosswind,
The rolling motion of the vehicle body caused by the occurrence of the lateral acceleration may be rolling in the leeward side of the crosswind or rolling in the upwind side of the crosswind, and the steering angle does not match the magnitude of the steering angle. In this case, on the basis of the lateral acceleration, the second switching control means controls the states of the air spring and the shock absorber to be switched between hard and soft, whereby appropriate roll control is performed.

The steering angle of the steering wheel is detected by the steering angle detecting means. Further, the acceleration that occurs in the vehicle at least in the lateral direction is detected by the acceleration detecting means. Therefore, as the operation according to the invention of claim 1,
Based on the vehicle speed detected by the vehicle speed detecting means, first selecting means for preferentially selecting the first switching control means with respect to the second switching control means and first switching means for the second switching control means are provided. By appropriately controlling the switching control means to the second selection means, which is selected with priority, it is possible to perform appropriate roll control from low speed to high speed.

Further, when the vehicle speed is high, that is, when the vehicle is traveling at high speed, the driver hardly steers, and the steering angle detected by the steering angle detecting means is small. Therefore, as an operation according to the invention described in claim 2, when the vehicle speed detected by the vehicle speed detecting means is low, the first switching control means is preferentially selected with respect to the second switching control means. However, when the vehicle speed detected by the vehicle speed detecting means is high, the second switching control means is preferentially selected with respect to the first switching control means, so that the switching control is performed based on the steering angle when the vehicle speed is low. Is done
At the time of high speed, the switching control is performed based on the lateral acceleration, so that it becomes possible to perform appropriate roll control from low speed to high speed.

According to the third aspect of the present invention, when the steering angle detecting means detects that the steering wheel is steered to the left, when the detected steering angle is equal to or greater than the predetermined angle, the driver Assuming that the vehicle rolls to the right in the traveling direction by steering the vehicle to the left, the first switching control means sets the right air spring in the vehicle to the hard state and the left air spring to the soft state. By setting the state, the static displacement in the sprung system is suppressed, and the shock absorber is switched to the hard state to suppress the dynamic displacement, and the vibration suppression control is performed.

Further, when it is detected by the steering angle detecting means that the steering wheel is steered to the right, when the detected steering angle is equal to or larger than the predetermined angle, the driver steers the vehicle to the right. Assuming that rolling of the vehicle body occurs on the left side in the traveling direction, the first switching control means causes the left air spring of the vehicle to be in a hard state and the right air spring to be in a soft state. In addition to suppressing the static displacement of the shock absorber, the shock absorber is switched to the hard state to suppress the dynamic displacement, and the vibration suppression control is performed.

As an operation according to the invention described in claim 4, when the lateral acceleration detected by the acceleration detecting means is equal to or more than a predetermined value, the vehicle receives a sudden side wind and a rolling motion occurs in the vehicle body. As the case may be, the second
By switching the state of each of the air spring and the shock absorber to a hard state by means of the switching control means, the rolling of the vehicle body to the leeward side of the crosswind and the rolling of the vehicle body to the upwind side of the crosswind are prevented, and vibration control is performed. To do.

[0020]

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. An air reservoir tank (not shown) in which compressed air is stored and the air spring 2 are connected by a supply / exhaust passage 21 having a leveling valve 4 for supplying and discharging compressed air to and from the air spring 2. Further, the inside of the air spring 2 and the sub tank 5 are communicated with each other by a communication passage 22 in which a spring constant switching valve 6 which is an electromagnetic valve as an opening / closing means for switching the spring constant is interposed.

Further, the control unit 9 having a built-in microcomputer has a changeover M signal from a mode changeover switch 10 described later, a vehicle speed V signal from a vehicle speed sensor 17 as a vehicle speed detecting means, and a steering angle detecting means as a steering angle detecting means. The steering angle θ signal from the angle sensor 11 and the lateral acceleration Y _g signal from the acceleration sensor 14 as the acceleration detecting means are input.

The control unit 9 has a first switching control means for switching the shock absorber 7 and the air spring 2 based on the steering angle θ signal, and the shock absorber 7 based on the lateral acceleration Y _g signal.
And the second switching control means for switching the air spring 2, the first selection means for selecting either the first switching control means or the second switching control means, the second selection means, and the first switching means. A switching control means for switching control to either the selection means or the second selection means is provided by software, and the actuator 8 of the damping force switching mechanism of the spring constant switching valve 6 and the shock absorber 7 is a micro controller. Switching control is performed by a control signal output from a control unit 9 having a built-in computer, and opening / closing control of the communication passage 22 and damping force switching control of the shock absorber 7 are performed.

FIG. 2 is a detailed control block diagram of the embodiment according to the present invention, in which the signal output from the mode changeover switch 10 is output through the mode signal input means 31 and the vehicle speed sensor 17. The signal is output through the vehicle speed signal input means 32, the signal output from the steering angle sensor 11 is output through the steering angle signal input means 33, and the signal output from the acceleration sensor 14 is output through the lateral acceleration signal input means 34. Input to the control means 35.

The control signal output from the control means 35 is applied to the spring constant switching valve 6 via the spring constant switching valve switching signal output means 36 and to the damping force of the shock absorber 7 via the shock absorber switching signal output means 37. Inputs are made to the actuators 8 of the switching mechanism. Next, the control content according to the embodiment will be described. The flowcharts shown in FIGS. 3, 4 and 5 show 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.

In step 1 (abbreviated as S1 in the drawing; the same applies hereinafter), the switching position of the mode changeover switch 10 is judged, and the mode is switched to the fixed mode of the hard mode (large spring constant) or the soft mode (small spring constant). Whether or not it is switched to the automatic mode in which the switching control is automatically performed. When the auto mode is selected, the process proceeds to step 2 and subsequent steps, and when the hard mode or the soft mode is selected, the switching control is not performed and the process directly returns.

In step 2, the vehicle speed signal V is read from the vehicle speed sensor 17, the steering angle θ signal from the steering angle sensor 11 and the lateral acceleration Y _g signal from the acceleration sensor 14 are read. The vehicle may be steered to the right or left, and the steering angle θ signal is a signal having positive and negative signs. Further, the lateral acceleration occurs in the vehicle, for example, if the crosswind from the left and right is applied to the vehicle, there is a case where the acceleration when the left acceleration to the right occurs caused by side wind, with the lateral acceleration Y _g The signal is also a signal having positive and negative signs.

In step 3, the vehicle speed signal V read from the vehicle speed sensor 17 is judged, and it is judged whether the vehicle speed is equal to or lower than a predetermined vehicle speed V _r, that is, whether the vehicle is traveling at low speed or traveling at high speed. . If it is determined that V ≦ V _r, it is determined that the vehicle is traveling at low speed, and step 4
If it is determined that V> V _r , the process proceeds to step 20 and onward, since the vehicle is traveling at high speed.

When it is determined that the vehicle is traveling at a low speed, the driver may steer a large amount, and the steering angle detected by the steering angle sensor 11 becomes large. The steering angle sensor 11 for detecting the
Based on the steering angle detected by 11, priority is given to the steering angle, and the control proceeds to step 4 and below in order to perform switching control for switching the states of the air spring and the shock absorber to hard or soft. On the other hand, when it is determined that the vehicle is traveling at high speed, the driver hardly steers, and the steering angle detected by the steering angle sensor 11 is small. In order to perform the switching control for switching the state of each of the air spring and the shock absorber to the hard state or the soft state based on the lateral acceleration preferentially, the process proceeds to step 20 and thereafter.

First, based on the steering angle detected by the steering angle sensor 11, the switching control of the spring constant switching valve 6 and the actuator 8 of the damping force switching mechanism of the shock absorber 7 is performed. Will be described. In step 4, the absolute value | θ | as the magnitude of the steering angle θ read from the steering angle sensor 11 is determined, and whether or not the steering angle is equal to or greater than a predetermined steering angle θ ₀ , that is, the driver turns the steering wheel largely Determine whether you are operating.

When it is determined in step 4 that the vehicle is not steered that much (| θ | <θ ₀ ), if the driver is not steering the vehicle and the vehicle body 20 rolls, Assuming that the vehicle was subjected to a sudden crosswind during traveling, proceed to Step 5 and subsequent steps, and set the lateral acceleration Y
Switching control of the spring constant switching valve 6 and the actuator 8 of the damping force switching mechanism of the shock absorber 7 is performed based on the _g signal.

In step 5, reading from the acceleration sensor 14
Embedded lateral acceleration Y_gAbsolute value as the magnitude of | Y_g|
Judgment, the lateral acceleration is the predetermined lateral acceleration Y_g0Is it above
To judge. Here, the predetermined lateral acceleration Y_g0And more
Lateral acceleration Y_gWhen the vehicle acts on the vehicle, the car body 20 rolls.
Is the threshold to And there is a large acceleration
Ru (| Y_g│ ≧ Y_g0), The driver
When the lane is changed to the car body 20 without operating the steering wheel,
The inertial force due to the centripetal acceleration generated during turning may act.
However, the rolling related to the inertial force does not occur.
However, the vehicle is exposed to a sharp crosswind and
If there is a possibility that
Up to 6 or less, lateral acceleration Y _gSpring constant based on
Of the damping force switching mechanism of the switching valve 6 and the shock absorber 7.
Switching control of the actuator 8 is performed.

In step 6, the positive / negative of the lateral acceleration Y _g signal read from the acceleration sensor 14 is judged,
Determine if the vehicle body 20 is rolling left or right. If it is determined that the vehicle is rolling to the left, go to step 7. Here, when it is detected that the vehicle body 20 is rolling to the left, in step 7, the right spring constant switching valve 6 is opened to make the right air spring 2 in the soft state and the left spring constant switching valve. 6
Is closed to bring the left air spring 2 into a hard state to suppress static displacement in the sprung system. Furthermore, the actuator 8 of the damping force switching mechanism of the shock absorber 7 on the right side is controlled to be in the soft state, and the actuator 8 of the damping force switching mechanism of the shock absorber 7 on the left side is also controlled to be in the hard state to suppress the dynamic displacement. Vibration suppression control is performed.

If it is determined in step 6 that the vehicle body 20 is rolling to the right, the process proceeds to step 8. Here, when it is detected that the vehicle body 20 is rolling to the right, in step 8, the left spring constant switching valve 6 is opened to make the left air spring 2 in the soft state and the right spring constant switching valve. By closing 6 to bring the right side air spring 2 into a hard state, static displacement in the sprung system is suppressed. Further, the actuator 8 of the damping force switching mechanism of the left shock absorber 7 is switched to the soft state, and the actuator 8 of the damping force switching mechanism of the right shock absorber 7 is also controlled to the hard state to suppress the dynamic displacement. Vibration suppression control is performed.

Next, in steps 9 to 12, it is determined how long the vibration damping control started in step 7 or step 8 is continued. That is, in step 9, the absolute value | Y _g | as the magnitude of the lateral acceleration Y _g read from the acceleration sensor 14 is determined, and it is determined whether or not the lateral acceleration is less than the predetermined lateral acceleration Y _g0 , that is, the vehicle body during traveling.
It is determined whether or not the rolling generated in the vehicle body 20 has subsided due to the sudden crosswind of 20. When it is determined that the lateral acceleration is less than the predetermined lateral acceleration Y _g0 (| Y _g | <Y _g0 ), the action of the inertial force due to the centripetal acceleration generated in the vehicle body 20 is also terminated, and rolling may occur. No more, go to step 10.

In step 10, the delay timer Tdt1 starts counting. In step 11, the absolute value | Y _g | as the magnitude of the lateral acceleration Y _g is determined again, and it is determined whether the lateral acceleration is less than the predetermined lateral acceleration Y _g0 . Then, it becomes less than the predetermined lateral acceleration Y _g0 (| Y _g |
If it is determined that <Y _g0 ), the process proceeds to step 12, and if it is determined that the lateral acceleration is not less than the predetermined lateral acceleration Y _g0 (| Y _g | ≧ Y _g0 ), the process returns to step 9.

In step 12, it is judged whether or not the count of the delay timer Tdt1 is finished, and if it is judged that Tdt1 has passed, the air spring 2 and the shock absorber 7 of the lateral acceleration damping control are controlled. It is assumed that the switching control is performed, the lateral acceleration Y _g generated by the lateral wind or the like becomes small, and the static displacement related to the lateral acceleration damping control becomes small, and this routine is ended. With the end, the spring constant switching valve 6 is opened to return the air spring 2 to the soft state to secure the riding comfort. Also, Tdt
If it is determined that 1 has not elapsed, step 11
Return to.

On the other hand, if it is determined in step 4 that the vehicle is being steered greatly (| θ | ≧ θ ₀ ), the driver is steering the vehicle, and the vehicle body 20 is generated when changing lanes or turning. Assuming that there is a possibility that the inertial force due to the centripetal acceleration acts to cause the rolling, the process proceeds to step 13 and below, and the damping force switching of the spring constant switching valve 6 and the shock absorber 7 is switched based on the steering angle θ. Switching control of the actuator 8 of the mechanism is performed.

In step 13, whether the vehicle is steered to the right or left is determined by determining whether the steering angle θ signal read from the steering angle sensor 11 is positive or negative. If it is determined that the vehicle is steered to the right, the process proceeds to step 14. Here, when it is detected that the steering wheel has been steered to the right by the predetermined steering angle θ ₀ or more, it is possible that the driver steers the vehicle to the right to cause rolling of the vehicle body 20 on the left side in the traveling direction. In step 14, the spring constant switching valve 6 on the right side is opened to make the air spring 2 on the right side in the soft state, and the spring constant switching valve 6 on the left side is closed to make the air spring 2 on the left side in the hard state. Suppresses static displacement in the upper system. Further, the actuator 8 of the damping force switching mechanism of the shock absorber 7 on the right side is controlled to be in the soft state, and the actuator 8 of the damping force switching mechanism of the shock absorber 7 on the left side is also controlled to be in the hard state to suppress the dynamic displacement. Vibration suppression control is performed.

If it is determined in step 13 that the vehicle is steered to the left, the process proceeds to step 15. Here, when it is detected that the steering wheel has been steered to the left by a predetermined steering angle θ ₀ or more, it is determined that the driver has steered the vehicle to the left to cause rolling of the vehicle body 20 on the right side in the traveling direction. Assuming that there is, in step 15, the actuator 8 of the damping force switching mechanism of the spring constant switching valve 6 and the shock absorber 7 is controlled to switch the right side to the hard state and the left side to the soft state, thereby performing static displacement and dynamics in the sprung system. Vibration suppression control is performed by suppressing displacement.

Next, in steps 16 to 19,
Which damping control started in step 14 or step 15
Determine whether to continue until the timing. That is, the step
In the case of 16, the steering angle θ read from the steering angle sensor 11 is large.
The absolute value | θ |
θ₀Whether or not it is less than, that is, the steering wheel operation by the driver
Judge whether the work is finished or not. Then, the predetermined steering angle θ
₀Became less than (| θ | <θ₀) Is judged
When the driver finishes steering and changes the lane to the body 20,
The action of inertial force due to centripetal acceleration generated during turning has also ended
However, if there is no possibility of rolling,
Go to step 17.

In step 17, the delay timer Tdt2
Start counting. In step 18, the steering angle
The absolute value | θ | as the magnitude of θ is the predetermined steering angle θ ₀Less than
It is determined whether or not Then, the predetermined steering angle θ₀Not yet
It is full (| θ | <θ₀), The status is
Prop. 19₀Or more (| θ | ≧ θ
₀), The process returns to step 16.

In step 19, it is judged whether or not the count of the delay timer Tdt2 has ended. If it is judged that Tdt2 has elapsed, the air spring 2 and the shock absorber 7 are switched by the swing vibration suppression control. The control is performed, the lateral acceleration Y _g generated by the turning becomes small, and the static displacement related to the turning damping control becomes small, the present routine is ended. With the end, the spring constant switching valve 6 is opened to return the air spring 2 to the soft state to secure the riding comfort. If it is determined that Tdt2 has not elapsed, the process returns to step 18.

Here, as is clear from the description of steps 4 to 19, steps 5 to 12 perform the function of the second switching control means according to claim 1, and
Steps 13 to 19 perform the function of the first switching control means according to claim 1. Further, Step 13 to Step 15 perform the function of the first switching control means according to claim 3,
Steps 6 to 8 perform the function of the second switching control means according to claim 4.

Further, the judgment in step 4 is made by determining the first switching control means after step 13 to the second switching step after step 5.
It is determined that the switching control means of (1) is preferentially selected, and thus step 4 has the function of the first selection means. Next, a case will be described in which it is determined in step 3 that the vehicle speed signal V is higher than a predetermined vehicle speed (high speed traveling), that is, V> V _r , and the process proceeds to step 20 and thereafter.

In this case, as described above, the acceleration sensor 14
Based on the lateral acceleration detected by, the switching control of the spring constant switching valve 6 and the actuator 8 of the damping force switching mechanism of the shock absorber 7 is performed. The function of each step in step 20 to step 27 is the same as in step 5 above.
~ The function is the same as in step 12, and the description is omitted. The delay timer Tdt3 in steps 25 and 27 is the same timer as the delay timer Tdt1 in steps 10 and 12.

The function of each step in step 28 to step 35 is the same as the function in step 4 and step 13 to step 19, and the description thereof will be omitted.
The delay timer Tdt4 in step 33 and step 35 is the same timer as the delay timer Tdt2 in step 17 and step 19. Where the steps
As is clear from the description of 20 to step 35, steps 20 to 27 function as the second switching control means according to claim 1, and step 28 to step 35 are the first switching according to claim 1. Plays the function of control means.

Further, the steps 21 to 23 are claimed in claim 3.
The function of the first switching control means according to the present invention is performed, and steps 29 to 31 function as the second switching control means according to claim 4. Further, the determination in step 20 is made by using the second switching control means after step 21 in step 28.
It is determined that the subsequent first switching control means should be preferentially selected, and thus step 20 has the function of the second selection means.

Further, as is clear from the above description of steps 1 to 35, in step 3, when the vehicle speed detected by the vehicle speed detecting means is below a predetermined value, the mode is switched to the first selecting means. When the vehicle speed is controlled, and the vehicle speed is higher than the predetermined value, the switching control is performed to the second selecting means, so that the step 3 functions as the switching control means.

Therefore, according to this embodiment, the vehicle speed V is V _r
If it is smaller, the driver may steer a large amount, and it is more effective to perform the roll control related to the steering. First, the roll control by the steering angle θ is performed as follows. . That is, when the steering angle θ is equal to or greater than the predetermined steering angle θ _r , the driver operates the steering wheel to
Assuming that the steering wheel is largely steered, and the rolling force is applied to the vehicle body by the inertial force due to the centripetal acceleration generated at the time of changing lanes or turning, based on the steering angle θ,
The states of the air spring 2 and the shock absorber 7 are controlled to be switched between hard and soft.

On the other hand, when the vehicle speed V is equal to or higher than V _r , the vehicle is traveling at a high speed, so that the driver hardly steers a large amount and it is more effective to perform the roll control related to the lateral acceleration. First, the roll control relating to the lateral acceleration was carried out as follows. That is, if the vehicle body rolls, the air spring 2 and the shock absorber 7 are determined based on the detected lateral acceleration G _Y as the rolling motion of the vehicle body caused by a sudden side wind when the vehicle travels. By controlling the switching of each state to hardware, rolling of the vehicle body to the leeward side of the crosswind and rolling of the vehicle body to the upwind side of the crosswind are prevented, and damping control is performed.

That is, according to this embodiment, which of the roll control based on the steering angle θ and the roll control based on the lateral acceleration Y _g is preferentially determined in view of the vehicle speed V, so that the steering with high accuracy is performed. Even without providing the angle sensor, appropriate roll control can be performed from low speed to high speed, the generated vehicle body vibration is effectively damped, and stable posture control is performed.

Further, in the present embodiment, when the turning / turning vibration suppression control or the lateral acceleration vibration suppression control is being performed, the timers Tdt1 to Tdt4 cause the timers Tdt1 to Tdt4.
Since the control state is continued during the period, the free damping motion in the free vibration can be accelerated, and there is an effect that the hunting for executing and releasing the switching control can be further prevented.

[0053]

The rolling of the vehicle body occurs when the inertial force due to the centripetal acceleration generated when the lane is changed or when the vehicle is turning is applied to the vehicle body, and when the vehicle receives a sudden side wind, the side wind causes the vehicle to roll. There may be a case where an external force is directly applied to. Here, the rolling motion of the vehicle body caused by the inertial force due to the centripetal acceleration generated when changing lanes or turning, the steering direction and the rolling motion direction are the same. The rolling motion of the vehicle body generated due to the reception is not the same as the steering angle, while the vehicle body may roll to the leeward side of the crosswind and the vehicle body may roll to the upwind side of the crosswind.

Therefore, according to the first aspect of the present invention, the first switching control means is preferentially selected with respect to the second switching control means based on the vehicle speed detected by the vehicle speed detection means. Appropriate roll control from low speed to high speed is performed by switching control between the selection means and the second selection means for preferentially selecting the second switching control means with respect to the first switching control means. Made possible.

Further, the driver rarely steers largely during high-speed traveling, and it is more effective to perform roll control related to lateral acceleration, and the driver may steer largely during low-speed traveling. It is more effective to perform such roll control. Therefore, according to the second aspect of the invention, when the vehicle speed is low, the first switching control means is preferentially selected, and when the vehicle speed is high, the second switching control means is preferentially selected. By making a selection, switching control is performed based on the steering angle at low speeds, and switching control is performed based on lateral acceleration at high speeds, making it possible to perform appropriate roll control from low speeds to high speeds.

Further, since the roll control relating to the steering angle is prioritized at a low speed when the driver steers a large amount and the roll control relating to the steering angle is not prioritized at a high speed where the steering angle is small, the steering angle is detected. With respect to the steering angle sensor, it is not necessary to have a highly accurate steering angle sensor, and it is not necessary to attach the steering angle sensor with high accuracy, which is advantageous in terms of technology and cost. There is also.

According to the third aspect of the present invention, when the vehicle is steered to the right or to the left, the air springs on the side depressed by rolling are individually switched to be hard. Since the control is performed, it is possible to reliably deal with the rolling operation that occurs when changing lanes or turning. Further, according to the invention described in claim 4, when the lateral acceleration is equal to or more than a predetermined value, the states of the air spring and the shock absorber are controlled to be switched to hardware, so that the vehicle receives a sudden side wind during traveling. As a result, even if rolling occurs on the leeward side or the windward side of the crosswind, it is possible to deal with either of them.

[Brief description of drawings]

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

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

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

FIG. 4 is a flowchart illustrating the contents of switching control according to the embodiment.

FIG. 5 is a flowchart illustrating the contents of switching control according to the embodiment.

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

[Explanation of symbols]

 1 Tire 2 Air Spring 4 Leveling Valve 5 Sub Tank 6 Spring Constant Switching Valve 7 Shock Absorber 8 Actuator 9 Control Unit 11 Steering Angle Sensor 14 Acceleration Sensor 17 Vehicle Speed Sensor

Claims (4)

[Claims] 1. An air spring for supporting at least one sprung system provided between a sprung system and front, rear, left and right unsprung systems of a vehicle; and a sprung system and each of the unsprung systems. An air suspension device for a vehicle, comprising: at least one shock absorber provided between the vehicle and the vehicle; a vehicle speed detecting means for detecting a vehicle speed; a steering angle detecting means for detecting a steering angle of a steering; An acceleration detecting means for detecting an acceleration including a direction; and a first switching control means for controlling the states of the air spring and the shock absorber to be switched between hard and soft based on the steering angle detected by the steering angle detecting means. , Based on the lateral acceleration detected by the acceleration detecting means,
Second switching control means for controlling the states of the air spring and the shock absorber to be switched between hard and soft, and a first switching control means for preferentially selecting the second switching control means with respect to the second switching control means. Based on the vehicle speed detected by the selecting means, the second selecting means for preferentially selecting the second switching control means with respect to the first switching control means, and the vehicle speed detected by the vehicle speed detecting means, the first selection A switching control means for switching control of either the control means or the second selection means, and an air suspension device for a vehicle. 2. The switching control means controls the switching to the first selecting means when the vehicle speed detected by the vehicle speed detecting means is a predetermined value or less, and the second control means when the vehicle speed is higher than the predetermined value. 2. The vehicle air suspension device according to claim 1, wherein the switching control is performed by the selection unit. 3. When the steering angle detecting means detects that the steering wheel is steered to the left, the first switching control means sets the right air spring in the vehicle to a hard state and the left air spring to the vehicle. If the steering angle detecting means detects that the steering wheel is steered to the right, the shock absorber is switched to the soft state and the shock absorber is switched to the hard state. The air suspension device for a vehicle according to claim 1 or 2, wherein the shock absorber is controlled to be switched to a hard state and to a hard state. 4. The second switching control means, when the lateral acceleration detected by the acceleration detecting means is equal to or more than a predetermined value, performs hardware switching control of the respective states of the air spring and the shock absorber. The vehicle air suspension device according to any one of claims 1 to 3.