JPH0899515A - Controller for electron controlled air suspension car - Google Patents

Abstract

PURPOSE: To restrict vehicle body vibration in a low frequency region and a whole frequency region in traveling on a bad road by judging a resonance state from an output signal of an unsprung vertical direction acceleration sensor and its hourly changes and judging bad road traveling based on this so as to control an air suspension. CONSTITUTION: A shock absorber 7 incorporating an air spring 2 and a damping force switch mechanism between a car body 20 and a tire 1, and up/down G sensors 15a, 15b for right and left are arranged in the adjacent to axles of the front wheel right and the rear wheel left so that a signal is input in a control unit 9 along with a signal of a speed sensor 17. This control unit 9 judges the resonance state of the vehicle from the up/down G sensors 15a, 15b and the hourly changes so as to judge a bad road traveling state from this judgement. And a control signal is output to a spring constant switch valve 6 and an actuator 8 of the damping force switch mechanism so as to control switching of damping force to hard or soft one. Therefore, vibration due to sprung rolling, etc., is surely detected so as to effectively restrict a vibration state of the vehicle body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electronically controlled air suspension vehicle, and more particularly, by increasing the vertical acceleration detection sensitivity of a sprung system detected by an acceleration sensor,
The present invention relates to a technology for suppressing body vibration in a low frequency range such as rolling, pitching, and bouncing, and body vibration in a whole frequency range when traveling on a rough road.

[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. 8, a sub-tank 86 communicating with the inside of the air spring 83 through 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 an 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 to 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).

By the way, the vibration of the vehicle body is caused by rolling, which is the rotational movement of the vehicle body about the longitudinal axis passing through the center of gravity of the sprung body, when overcoming large irregularities on the road surface, or when traveling on a corrugated road at an appropriate speed. There are pitching, which is the vibration of the vehicle about a certain vehicle left-right direction axis, and bouncing in which the sprung system of the vehicle vibrates in the vertical direction.

Therefore, the applicant of the present invention determines the resonance state of the vehicle based on the output signal of the vertical G sensor provided on the vehicle body and the temporal change of the output signal, and determines the vehicle resonance state based on the resonance state of the vehicle. A control device for an electronically controlled air suspension vehicle that is capable of reliably detecting rolling, pitching or bouncing occurrence by judging bad road traveling, and applying for an electronically controlled air suspension vehicle controller first (Japanese Patent Application No. 6-61322).

[0008]

By the way, in the above application, the filter circuit for detecting the motion state such as pitching, bouncing, etc. can be abolished, and the control can be performed while ensuring the responsiveness. Although it is possible to reliably detect running on a rough road, there is still room for improvement when the vertical G sensor that detects the vibration state of the vehicle body is attached to the vehicle body.

Therefore, the present invention has been made in view of the above situation, and more reliably detects the vibration state of the vehicle body such as rolling, pitching, or bouncing, and more effectively suppresses the generated vehicle body vibration. It is an object of the present invention to provide a control device for an electronically controlled air suspension vehicle that enables the above.

[0010]

Therefore, according to the invention of claim 1, at least one air-supporting system is provided between a sprung system and each unsprung system on the front, rear, left and right sides of the vehicle to support the sprung system. A spring, at least one shock absorber provided between the sprung system and each of the unsprung systems, and control means for switching the states of the air spring and the shock absorber to hard or soft. An electronically controlled air suspension vehicle control device comprising: at least one acceleration sensor provided at positions on a front axis and a rear axis facing a center of gravity of the vehicle, for detecting vertical acceleration of the sprung system; Resonance state determination means for determining the resonance state of the vehicle based on the output signal of the acceleration sensor and the temporal change of the output signal, and the resonance state determination hand. Based on the resonance state of the vehicle is determined by, and a structure comprising a rough road running condition determining means for determining the state where the vehicle is a rough road.

[0011]

When the sprung system of the vehicle vibrates due to rolling, the sprung system vibrates left and right with respect to the center of gravity of the vehicle. When the sprung system of the vehicle vibrates due to pitching, the sprung system vibrates back and forth with respect to the center of gravity of the vehicle. Further, when the sprung system of the vehicle vibrates due to bouncing, the sprung system simultaneously vibrates in the same direction with respect to the center of gravity of the vehicle.

Therefore, as an operation according to the first aspect of the present invention, at least one acceleration sensor is provided at a position on the front shaft and the rear shaft facing the center of gravity of the vehicle.
Vibration related to rolling, pitching or bouncing of the sprung system can be reliably detected by the acceleration sensor. Then, the resonance state determination means determines the resonance state of the vehicle based on the vertical acceleration and the temporal change in the vertical acceleration. Here, since the vertical acceleration and the temporal change of the vertical acceleration are different depending on the running state of the vehicle (for example, low-frequency vibration described later or running on a bad road), the bad road running state determination means is set to the resonance state. Based on this, it is determined whether the vehicle is traveling on a rough road.

[0013]

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.

Here, in this embodiment, as shown in FIG. 2, a right upper and lower G is provided on the outermost right side of the front wheel axle 25 of the vehicle body 20.
The sensor 15a is arranged, the left vertical G sensor 15b is arranged on the left outermost side in the vicinity of the rear wheel axle 26 of the vehicle body 20, and the output signals G _zr and G _zl are inputted to the control unit 9. Here, the vehicle center of gravity 28 of the vehicle body 20 is substantially at the center position of the front wheel axle 25 and the rear wheel axle 26, and is also at the center position of the vehicle body 20 in the left-right direction.

Further, the control unit 9 is supplied with a changeover M signal from a mode changeover switch 10 and a vehicle speed V signal from a vehicle speed sensor 17, which will be described later. Then, in the control unit 9, the output signal G _zr of the up / down right G sensor 15a and the output signal G _{zl of the} up / down G sensor 15b for left are provided.
And a resonance state determination means for determining the resonance state of the vehicle based on the temporal changes of the output signals G _zr and G _zl , and the vehicle based on the resonance state of the vehicle determined by the resonance state determination means. The vehicle is equipped with a rough road traveling state judging means for judging the state of traveling on a rough road 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 microcomputer. Switching control is performed by a control signal output from the built-in control unit 9, and opening / closing control of the communication passage 22 and damping force switching control of the shock absorber 7 are performed.

FIG. 3 is a detailed control block diagram, in which the signal output from the mode changeover switch 10 is input via the mode signal input means 31, and the signal output from the vehicle speed sensor 17 is input into the vehicle speed signal. Control means 35 via means 32
Entered in. Further, the output signal G _zr from the right up and down G sensor 15a is sent through the front right position vertical acceleration signal input means 33, and the output signal G _zl from the left up and down G sensor 15b is sent through the front left position vertical acceleration signal input means 34. It is input to the control means 35 via the.

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 switching control content 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 will be described with reference to the flowchart shown in FIG.

In step 1 (abbreviated as S1 in the figure, the same applies hereinafter), the switching position of the mode changeover switch 10 is determined, and the mode is switched to a fixed mode of a hard mode (large spring constant) or a 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 read from the vehicle speed sensor 17 is determined to determine whether the vehicle speed is 0, that is, whether the vehicle is traveling. And the vehicle speed is 0
If not, go to step 3 and below,
When the vehicle speed is 0, the vehicle is stopped and it is determined that the switching control is not performed, and the process directly returns. In step 3, the output signal G _zr from the right upper G sensor 15a,
And the output signal G _zl from the left and right upper and lower G sensors 15b is read.

In this embodiment, the right vertical G sensor 15a is disposed on the right outermost side of the vehicle body 20 near the front wheel axle 25, and the left vertical G sensor 15b is located near the rear wheel axle 26 of the vehicle body 20. Since it is arranged on the outermost left side of the vehicle, vibrations caused by rolling, pitching or bouncing of the vehicle body 20 that occur when the vehicle travels can be reliably detected by the right vertical G sensor 15a or the left vertical G sensor 15b. It will be.

In step 4, the sprung resonance range level Zs is set.
And the unsprung resonance band level Zu are calculated according to the following equation. _{Zs = | G zr | × |} G zl | Zu = | G zri -G zri-1 | × | G zli -G zli-1 | However, | G _zr | is the absolute value of the output signal G _zr, | G _zl | Is the absolute value of the output signal G _zl , the subscript i represents the output signal related to the current calculation, and the subscript (i−1) represents the output signal related to the previous calculation.

That is, the sprung resonance range level Zs is the product of the absolute values of the output signals G _zr and G _zl of the left and right upper and lower G sensors 15a and 15b. It is a judgment. The unsprung resonance range level Zu is the product of the absolute values of the changes in the output signals G _zr and G _zl of the left and right upper and lower G sensors 15a and 15b, and determines the magnitude of the vibration level in a specific frequency range. .

First, referring to FIGS. 5 and 6, the vibration state will be described based on the level of vertical acceleration when the vehicle vibrates in various ways. FIG. 5 schematically shows the level of vertical acceleration when the sprung system of the vehicle vibrates due to rolling, pitching or bouncing. As is clear from this figure, the spring of the vehicle is When the upper system vibrates due to rolling, pitching or bouncing, the vibration in the low frequency range becomes large (point H).

FIG. 6 schematically shows the level of vertical acceleration when the sprung system of the vehicle is vibrating due to running on a bad road of the vehicle. As is clear from this figure, When the sprung system of the vehicle is vibrating due to the vehicle traveling on a bad road, the vibration is large over the entire frequency range (points I and J). Next, the relationship between the sprung resonance range level Zs and the unsprung resonance range level Zu and the vibration state of the vehicle will be described with reference to FIG. 7.

The time chart shown in FIG. 7 shows a case where the sprung system of the vehicle vibrates on the left side in the figure due to rolling, pitching or bouncing (hereinafter referred to as low frequency vibration). On the right side, vibration due to traveling on a rough road of the vehicle (hereinafter referred to as traveling on a rough road) is shown. As shown in FIG. 7 (a), when the vehicle is traveling at low frequency or traveling on a bad road, the left and right upper and lower G sensors 15a and 15b detect a predetermined vibration. Each output signal G _zr ,
G _zl also becomes an output above a predetermined level.

When the vehicle is vibrating at a low frequency, the sprung resonance range level Zs becomes large (see FIG. 7).
It has been clarified from the experiment that the unsprung resonance region level Zu falls within a predetermined level (see (b)) (see FIG. 7C). On the other hand, when the vehicle is traveling on a rough road, the sprung resonance range level Zs increases (see FIG. 7B) and the unsprung resonance range level Zu also increases without falling within a predetermined level (see FIG. 7B). 7 (c)) became clear from the experiment.

Therefore, by determining the sprung resonance range level Zs and the unsprung resonance range level Zu, it is possible to judge the vibration state of the vehicle. Again, returning to the description of FIG. In step 5, it is determined whether or not the sprung resonance range level Zs calculated in step 4 is larger than a predetermined value (threshold value) Za. When it is determined that Zs> Za, the vibration level in the entire frequency range of the sprung system is large, and the rolling, pitching, or bouncing is large, so that the vibration level in the entire frequency range is large. However, the process proceeds to step 6.

In step 6, it is determined whether the unsprung resonance region level Zu calculated in step 4 is larger than a predetermined value (threshold value) Zb. When it is determined that Zu ≦ Zb, it can be determined that the sprung system of the vehicle is vibrating at a low frequency due to rolling, pitching or bouncing, as described above. Go to step 7 and step 8.

In steps 7 and 8, the spring constant switching valve 6 is opened to switch the spring constant to a small value in order to damp low-frequency vibrations of the vehicle.
And the shock absorber 7 is controlled by hardware. As a result, the damping rate is increased, and as shown in FIG. 5, the damping effect against the low frequency vibration of the vehicle is exhibited.

That is, the steps 5 to 8 are claimed in claim 1.
The function of the resonance state determination means is performed. Next, step 9 and subsequent steps are performed, but in steps 9 and 10, Z
not s> Za, or Zs> Za and Z
When u> Zb, that is, when it is determined that the low-frequency vibration of the vehicle has decreased, the process proceeds to step 11, the operation of the delay timer is started, and the delay time Tdv1 is set.

Then, after starting the operation of the delay timer, the process proceeds to step 12 and step 13, where Zs> Za again.
Or Zs> Za and Zu> Zb
Then, it is determined whether the delay time Tdv1 has elapsed. That is, the vibration state changes due to a change in the running state, the output signals G _zr and G _{zl of} the left and right upper and lower G sensors 15a and 15b change, and thus the sprung resonance region level Zs and the unsprung resonance region level Zu change. However, since the switching control of the spring constant switching valve 6 and the actuator 8 is performed based on the sprung resonance region level Zs and the unsprung resonance region level Zu, it is determined that the low frequency vibration is reduced. If the switching control is immediately performed in such a case, there is a possibility that the control stability in the switching control cannot be ensured.

Therefore, in this embodiment, step 9
In step 14, delay control is performed as shown in FIG. 7 (f) to ensure control stability in switching control of the spring constant switching valve 6 and the actuator 8 as shown in FIGS. 7 (d) and (e). are doing. On the other hand, in step 6,
If it is determined that the unsprung resonance range level Zu is Zu> Zb, it can be determined that the vehicle is traveling on a rough road, as described above.
Go to step 16.

In steps 15 and 16, the spring constant switching valve 6 is closed and the spring constant is switched to a large value in order to suppress the vibration of the vehicle caused by the vehicle traveling on a bad road. The air spring 2 is controlled to be switched to hardware, and the actuator 8 is switched to control the shock absorber 7 to be switched to hardware. As a result, the so-called vibration system as a whole is made hard to reduce the amount of flexure of the suspension as shown in FIG. 6 and to cause bottoming (for example, a shock caused by the action of a suspension stopper of the suspension) when traveling on a rough road. It is possible to prevent this, and the riding comfort is greatly improved.

That is, steps 5, 6 and steps 15, 16
Fulfills the function of the rough road running condition judging means. Next, the process proceeds to step 17 and below, but in step 17 and step 18, if Zs> Za is not satisfied or Zs> Za
However, if Zu> Zb is not satisfied, that is, if it is determined that the vehicle has run on a rough road, the routine proceeds to step 19, the operation of the delay timer is started, and the delay time Tdv2 is set.

Then, after starting the operation of the delay timer, the process proceeds to step 20 and step 21, where Zs> Za again.
It is determined whether or not Zu> Zb even if Zs> Za, and whether or not the delay time Tdv2 has elapsed. That is, the vibration state changes due to the end of traveling on a rough road, and the output signals G _zr and G _{zl of} the left and right upper and lower G sensors 15a and 15b change, so that the sprung resonance range level Z.
s and the unsprung resonance region level Zu change, but since the switching control of the spring constant switching valve 6 and the actuator 8 is performed based on the sprung resonance region level Zs and the unsprung resonance region level Zu. However, if the switching control is immediately performed because the traveling on the rough road is stopped even for a moment, the control stability in the switching control may not be ensured.

Therefore, in this embodiment, step 17
In step 22, delay control is performed as shown in FIG. 7F to secure control stability in switching control of the spring constant switching valve 6 and the actuator 8 as shown in FIGS. 7D and 7E. are doing. As described above, in the present embodiment, the right vertical G sensor 15a is disposed on the right outermost side in the vicinity of the front wheel axle 25 of the vehicle body 20, and the left vertical G sensor 15a is disposed.
15b is disposed on the left outermost side in the vicinity of the rear wheel axle 26 of the vehicle body 20, and is located on the right vertical G sensor 15a or the left vertical G sensor 15
an output signal G _zr relating to the acceleration reliably detected by b,
Spring constant switching valve 6 and actuator 8 based on G _zl
Therefore, it is possible to more effectively suppress the vibration state of the vehicle body such as rolling, pitching or bouncing.

[0037]

As described above, according to the first aspect of the present invention, at least one acceleration sensor is provided at the position on the front axis and the rear axis facing the center of gravity of the vehicle. Vibration due to rolling, pitching or bouncing of the sprung system is reliably detected by the sensor, and vibration damping control is performed based on the output signal relating to the acceleration reliably detected by the acceleration sensor. It is possible to effectively suppress the vibration state of the vehicle body such as pitching or bouncing.

[Brief description of drawings]

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

FIG. 2 is a schematic perspective view showing the arrangement of the acceleration sensor according to the embodiment.

FIG. 3 is a control system diagram of the above embodiment.

FIG. 4 is a flowchart illustrating the control contents of the above embodiment.

FIG. 5 is a characteristic diagram illustrating the control action of the above embodiment.

FIG. 6 is a characteristic diagram illustrating the control action of the above embodiment.

FIG. 7 is a time chart explaining the control action of the above embodiment.

FIG. 8 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 15a Right Up / Down G Sensor 15b Left Up / Down G Sensor 17 Vehicle Speed Sensor

Claims (1)

[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 electronically controlled air suspension vehicle control device, comprising: a shock absorber, at least one of which is provided between the shock absorbers, and a control means for switching the states of the air spring and the shock absorber between hard and soft states. At least one acceleration sensor is provided at a position on the front axis and a rear axis facing each other to detect vertical acceleration of the sprung system, and based on an output signal of the acceleration sensor and a temporal change of the output signal. Then, based on the resonance state determination means for determining the resonance state of the vehicle, and the resonance state of the vehicle determined by the resonance state determination means, Serial vehicle rough road and bad road state determining means for determining a state that you are running, the electronic control air suspension vehicle control apparatus characterized by comprising a.