JPH0684126B2 - Stabilizer control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is, for example, a state in which the roll amount of a vehicle cannot be accurately estimated from the vehicle speed and the steering angle while the vehicle is traveling on a road surface having a low friction coefficient. The present invention relates to a stabilizer control device that effectively suppresses rolling of a vehicle due to excessive control of the amount of twist of the stabilizer even when it falls into the condition of.

[Prior Art] When a vehicle shifts to a turning traveling state, rolling occurs due to the action of centrifugal force. In this case, the camber angle also changes as the roll angle increases, so the canvas last increases and the maneuverability / stability is degraded. Therefore, in order to maintain the turning traveling state, it is necessary to frequently perform the correction steering. Controls such rolling and maneuverability
In order to improve the stability, it is possible to set a high spring constant of the suspension, for example. However, in this case, shocking vibrations, such as when traveling on a rough road, are not absorbed, and the riding comfort is reduced. Therefore, a stabilizer that acts as a spring and generates a restoring force only when the suspension positions of the left and right wheels are different is arranged in the vehicle to suppress rolling.

However, even when the vehicle is not rolling, for example, when one of the left and right wheels rides on a protrusion on the road surface, a difference occurs in the suspension position of the left and right wheels. Will act as. Therefore, the riding comfort is reduced as in the case where the spring constant of the suspension is set high. As a countermeasure against such a problem, for example, "stabilizer device" (Japanese Patent Laid-Open No. 61-64514) has been proposed.
That is, the stabilizer and the wheel-side member are connected by a cylinder unit having two cylinder chambers formed by a piston and a cylinder body, and both cylinder chambers are connected by a switching valve to a pressure fluid source. This is a technique for adjusting the pressure to expand and contract the cylinder unit, positively utilizing the action of the stabilizer, and controlling the posture of the vehicle to prevent rolling during turning of the vehicle.

[Problems to be Solved by the Invention] By the way, in the above-described conventional technique, the pressure fluid from the pressure fluid source is supplied to the cylinder unit to control the vehicle posture to be stable. However, if pressure fluid is supplied discontinuously or stepwise to the cylinder unit when performing such control, shocking vibration that gives an occupant an uncomfortable feeling, noise accompanying the vibration, and the like are generated in the vehicle. However, the ride quality was deteriorated. Therefore, the applicant of the present application is an improved technique for eliminating the discomfort felt by an occupant by continuously controlling the flow rate of the pressure fluid from the fluid pressure source to the cylinder unit by a flow rate control valve when actively controlling the stabilizer. Stabilizer control device "(Japanese Patent Application No. 62-1486
10) proposed.

However, the above-mentioned improved technique maps the target stroke amount of the cylinder unit, which is the control amount during turning of the vehicle, according to the lateral acceleration estimated from the vehicle speed detected by the vehicle speed sensor and the steering angle detected by the steering sensor. It was calculated according to. However, if the vehicle
When traveling on a road surface having a low coefficient of friction, such as a road surface wet with rain or a frozen road surface after snowfall, slippage of each wheel occurs due to slippage of drive wheels due to an increase in slip ratio and reduction of side force. In this way, when the vehicle shifts to low friction coefficient road surface running, the drive wheels are rotating at a predetermined speed, so the vehicle speed detected by the vehicle speed sensor becomes a large value, but the actual vehicle speed is extremely low or The steering angle does not reflect the actual turning radius of the vehicle because the vehicle is in a turning state with a relatively large skid. That is, the lateral acceleration actually acting on the vehicle has a relatively small value, but the lateral acceleration estimated from the detected vehicle speed and the steering angle has a considerably large value. Therefore, in such a case, if the control amount is determined according to the vehicle speed detected by the vehicle speed sensor and the lateral acceleration estimated from the steering angle detected by the steering sensor, the detection result of the vehicle speed sensor is considerably larger than the actual vehicle speed, In addition, since the steering angle detected by the steering sensor is much larger than the steering angle corresponding to the actual turning radius, the calculated control amount also becomes an excessively large value. For this reason, it has been found that the amount of twist of the stabilizer becomes too large and rolling occurs due to the active control of the stabilizer in the vehicle, and the above-mentioned improved technique is still not sufficient.

This makes the occupant feel uncomfortable and also deteriorates the riding comfort.

In addition, it is not always effective to execute the active control of the stabilizer in the same manner as in the normal case, such as during turning traveling on the low friction coefficient road surface as described above. Distinguishing from the case where the active control of the stabilizer effectively acts, such as during turning, that is, no consideration is given to the relationship between the difference in road surface condition and the control amount, and the active control of the stabilizer is
There is a new problem that the desired effect is not always exhibited, and there is still room for improvement.

The present invention, when the active control of the stabilizer is being executed, when the vehicle speed detected by the vehicle speed sensor of the vehicle and the steering angle detected by the steering sensor do not accurately reflect the turning state of the vehicle, for example, transition to low friction coefficient road surface traveling. At the same time, it is an object of the present invention to provide a stabilizer control device capable of suitably suppressing rolling of a vehicle caused by excessive control of the stabilizer.

Configuration of the Invention [Means for Solving the Problems] The present invention, which has been made to solve the above problems, is, as illustrated in FIG. 1, a stabilizer that connects both unsprung members that support left and right wheels of a vehicle. The twist amount adjusting means M1 for adjusting the twist amount of the vehicle according to an external command, the vehicle speed detecting means M2 for detecting the vehicle speed of the vehicle, the steering angle detecting means M3 for detecting the steering angle of the vehicle, and the stabilizer. Control for outputting a command to the twist amount adjusting means M1 to change the twist amount of the target twist amount determined according to the vehicle speed detected by the vehicle speed detecting means M2 and the steering angle detected by the steering angle detecting means M3. A stabilizer control device comprising means M4, further comprising: lateral acceleration detection means M5 for detecting lateral acceleration of the vehicle; vehicle speed detected by the vehicle speed detection means M2; and steering angle detection means M3. Estimated lateral acceleration calculation means M6 for calculating the estimated lateral acceleration of the vehicle from the steering angle that is output, and the ratio of the estimated lateral acceleration calculated by the estimated lateral acceleration calculation means M6 and the lateral acceleration detected by the lateral acceleration detection means M5. Is higher than a predetermined ratio, a lateral acceleration ratio determining means M7 for determining whether or not the vehicle is in a low friction coefficient road surface traveling state, and when the lateral acceleration ratio determining means M7 determines that the vehicle is in a low friction coefficient road surface traveling state. A gist of a stabilizer control device is characterized by comprising: a correction means M8 for reducing and correcting the target twist amount determined by the control means M4.

The twist amount adjusting means M1 is for adjusting the twist amount of the stabilizer according to a command from the outside. For example, a cylinder disposed on one of the unsprung member and a mounting portion of the stabilizer facing the unsprung member, and mounted on the other of the unsprung member and the mounting portion of the stabilizer facing the unsprung member. Piston slidably fitted to the cylinder, a hydraulic circuit connecting the upper and lower chambers of the cylinder divided by the piston to a hydraulic pressure source, and a direction switching inserted in the hydraulic circuit It can be realized by a valve and a flow control valve. Further, for example, between the unsprung member and the mounting portion of the stabilizer facing the unsprung member, a cylinder and a piston having a structure similar to a known damping force variable shock absorber are provided, and a control signal input from the outside is provided. Therefore, the piston may be arranged so as to interpose a connection actuator capable of sliding and fixing. Further, for example, the vertical position of the two bearing portions on the left and right where the stabilizer is attached to the vehicle body is changed by the hydraulic actuators disposed on the vehicle body side, or on the vehicle body side near the bearing portion. It is also possible to adopt a configuration using a hydraulic actuator that actively twists the stabilizer.
In this way, the hydraulic actuator is installed on the vehicle body side, that is,
When arranged on the spring, the vibration frequency of the sprung vibration is lower than that of the unsprung vibration by about one digit, so that the durability and reliability of the hydraulic actuator can be improved.

The vehicle speed detecting means M2 is for detecting the speed of the vehicle. For example, it can be realized by a reed switch type vehicle speed sensor provided inside the speedometer or an electromagnetic pickup type vehicle speed sensor that detects the rotation speed of the output shaft of the transmission.

The steering angle detection means M3 is for detecting the steering angle of the vehicle. For example, it can be realized by a potentiometer which is provided on the steering shaft and outputs a steering amount as an analog signal, or a steering sensor such as a rotary encoder which outputs a digital signal with high resolution.

The control means M4 outputs a command to change the twist amount of the stabilizer to the target twist amount determined according to the vehicle speed and the steering angle. For example, the target twist amount may be calculated based on a map that defines the relationship between the vehicle speed, the steering angle, and the target twist amount, or based on an arithmetic expression, and the command may be output. Further, for example, a stabilizer target capable of determining a moving load between inner and outer wheels in a turning traveling state based on a vehicle speed and a steering angle, and suppressing a vehicle body inclination (so-called rolling) caused by a deflection of a suspension device caused by the moving load. The amount of twist is calculated, and a command to positively twist the stabilizer by the target amount of twist is output (so-called Active Control).
May be configured to perform.

The lateral acceleration detecting means M5 is for detecting the lateral acceleration of the vehicle. For example, it can be realized by a strain gauge type acceleration sensor arranged near the center of gravity of the vehicle or a servo acceleration sensor.

The estimated lateral acceleration calculating means M6 is for calculating an estimated lateral acceleration of the vehicle from the vehicle speed detected by the vehicle speed detecting means M2 and the steering angle detected by the steering angle detecting means M3. For example, the estimated lateral acceleration can be calculated by dividing the power of the vehicle speed by the steering angle.

The lateral acceleration ratio determining means M7 means that the ratio of the estimated lateral acceleration calculated by the estimated lateral acceleration calculating means M6 to the lateral acceleration detected by the lateral acceleration detecting means M5 exceeds a predetermined ratio, and is in a low friction coefficient road surface running state. It is to determine whether or not. For example, when the lateral angular velocity ratio exceeds a predetermined ratio corresponding to a low friction coefficient road surface traveling state involving wheel slipping, skidding, etc., it may be determined that the vehicle is in a low friction coefficient road surface traveling state. Good.

The correction means M8 means the control means M4 when the lateral acceleration ratio determination means M7 determines that the vehicle is running on a low friction coefficient road surface.
The target amount of twist determined by is reduced and corrected. For example, the target amount of twist in a dry road surface running state can be configured to be multiplied by a correction coefficient smaller than value 1 to perform a reduction correction.
Further, for example, the correction coefficient corresponding to the reduction rate at the time of the reduction correction may be further increased or decreased according to the friction coefficient of the traveling road surface.

The control means M4, the estimated lateral acceleration calculation means M6, the lateral acceleration ratio determination means M7 and the correction means M8 can be realized by, for example, independent discrete logic circuits. Further, for example, a well-known CPU, ROM, RAM, and other peripheral circuit elements may be configured as a logical operation circuit, and each of the above means may be realized according to a predetermined processing procedure.

[Operation] In the stabilizer control device of the present invention, as illustrated in FIG. 1, the control means M4 controls the amount of twist of the stabilizer to detect the vehicle speed detected by the vehicle speed detection means M2 and the steering angle detected by the steering angle detection means M3. When outputting the command to change to the target twist amount determined according to the above, to the twist amount adjusting means M1, the estimated lateral acceleration is calculated from the vehicle speed detected by the vehicle speed detecting means M2 and the steering angle detected by the steering angle detecting means M3. The ratio of the estimated lateral acceleration of the vehicle calculated by the means M6 and the lateral acceleration detected by the lateral acceleration detecting means M5 exceeds a predetermined ratio, and it is determined by the lateral acceleration ratio determining means M7 that the vehicle is in a low friction coefficient road surface running state. And the target twist amount determined by the control means M4 is corrected by the correction means.
M8 works to reduce correction.

That is, when the ratio of the estimated lateral acceleration calculated from the vehicle speed and the steering angle to the detected lateral acceleration exceeds a predetermined ratio, it is determined that the vehicle is in a low friction coefficient road surface running state, and The target twist amount of the stabilizer determined by the above is corrected to be reduced.

Therefore, when the stabilizer control device of the present invention determines that the vehicle speed and the steering angle of the vehicle do not accurately reflect the actual turning state of the vehicle based on the lateral acceleration ratio, it is determined that the vehicle is in the low friction coefficient road surface running state. The target twist amount of the stabilizer, which is determined according to the vehicle speed and the steering angle, is corrected so as to be reduced, and the twist amount of the stabilizer is prevented from becoming an excessive amount greater than the twist amount required to suppress rolling of the vehicle.

The technical problems of the present invention are solved by the action of each component of the present invention as described above.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a system configuration of a stabilizer control device which is an embodiment of the present invention.

As shown in FIG. 1, the stabilizer control device 1 includes a front stabilizer device 2 and an electronic control device (hereinafter simply referred to as an ECU) 3 that controls the stabilizer device 2.

The front stabilizer device 2 supplies a connecting actuator 7 interposed between the left mounting portion of the front stabilizer bar 4 and the lower arm 6 of the left front wheel 5 and pressure oil boosted by the hydraulic source 8 to the connecting actuator 7. A connecting unit 10 including a valve actuator 9 for supplying, a right mounting portion of the front stabilizer bar 4 and a right front wheel 11
A stabilizer link 13 is provided to connect between the lower arm 12 and the lower arm 12.

On the other hand, the left stabilizer of the rear stabilizer bar 14 and the left front wheel
A stabilizer link 17 is provided between the lower arm 16 and the lower arm 16, and a stabilizer link 20 is provided between the right mounting portion of the rear stabilizer bar 14 and the lower arm 19 of the right rear wheel 18.
Are respectively connected by.

The stabilizer control device 1 includes, as detectors, a vehicle speed sensor 21 that detects a vehicle speed, a steering sensor 22 that detects a steering angle, and a lateral acceleration sensor 23 that is arranged near the center of gravity of the vehicle and detects lateral acceleration.

Next, the configurations of the coupling unit 10 and the ECU 3 will be described with reference to FIG. As shown in FIG. 3, the connecting unit 10 includes a connecting actuator 7 that adjusts the distance between the left mounting portion of the front stabilizer bar 4 and the lower arm 6 in accordance with the hydraulic pressure supplied from the valve actuator 9.
It is composed of a stroke sensor 24 which detects the interval (stroke amount) and outputs it to the ECU 3, and a valve actuator 9 which supplies pressure to the connecting actuator 7 by a hydraulic pressure source 8 to supply no pressure according to the control of the ECU 3.

In the coupling actuator 7, the piston 32 in which the piston rod 33 is continuously arranged is slidably fitted in the cylinder 31,
The piston 32 divides the inside of the cylinder 31 into an upper chamber 35 having a port 35a and a lower chamber 36 having a port 36a. The piston rod 33 is attached to the left mounting portion of the front stabilizer bar 4, while the cylinder 31
Are attached to the lower arms 6, respectively. Therefore, the stabilizer device 2 is moved by the movement of the piston 32 of the connecting actuator 7 over a predetermined stroke amount.
It is configured to change the torsional rigidity of the front stabilizer bar 4.

The hydraulic power source 8 also includes a constant-flow hydraulic pump 53 driven by the output shaft 52 of the engine 51 and a reservoir 54 that stores hydraulic oil.

Further, the valve actuator 9 outputs from the ECU 3 and the direction switching valve 41 (four-port three-position solenoid valve) that switches to the fixed position 41a, the contracted position 41b, and the extended position 41c according to the control signal output from the ECU 3. Flow rate control valve (linear solenoid valve) 42 for continuously changing the opening according to the duty ratio control signal. Here, the flow control valve 42 is a pipe line 61 connecting the hydraulic power source 8 and the direction switching valve 41.
And a conduit 62 that connects the direction switching valve 41 and the reservoir 54 to each other. In addition, the flow control valve
42 is switched at high speed between the communication position 42a and the blocking position 42b according to the duty ratio control signal output from the ECU 3, and the opening area thereof is changed from the fully open state (communication position 42a) to the fully closed state (blocking position). It is continuously adjustable up to 42b). In the present embodiment, the flow rate control valve 42 is fully opened when the duty ratio control signal is 100 [%], while the flow rate control valve 42 is fully closed when the duty ratio control signal is 0 [%]. I decided to.

As shown in the figure, the ECU 3 described above includes CPU3a, ROM3b, RAM3
It is configured as a logical operation circuit centering on c, and the common bus 3d
It is connected to the input unit 3e and the output unit 3f via the to input and output with the outside. The detection signals of the above sensors are input to the CPU 3a via the input unit 3e, while the CPU 3a outputs control signals to the direction switching valve 41 and the flow rate control valve 42 via the output unit 3f.

The ECU 3 outputs the control signals to the direction switching valve 41 and the flow rate control valve 42 to operate the connecting unit 10 having the above-described configuration as follows.

That is, when the direction switching valve 41 is switched to the fixed position 41a and the flow rate control valve 42 is in the fully open state (communication position 42a) by the control signal of the duty ratio 100 [%],
The hydraulic oil returns to the reservoir 54 via the hydraulic pump 53, the conduit 61, the direction switching valve 41, the flow rate control valve 42, and the conduit 62. Further, the hydraulic circuit that connects the upper chamber 35 and the lower chamber 36 of the cylinder 31 of the coupling actuator 7 is cut off. For this reason,
The piston 32 is fixed at the current position, and the interval (stroke amount) between the front stabilizer bar 4 and the lower arm 6 is maintained at a constant interval, which is a so-called hold state.

On the other hand, when the direction switching valve 41 is switched to either the contracted position 41b or the expanded position 41c, and the flow rate control valve 42 is in the fully open state (communication position 42a) by the control signal of the duty ratio 100 [%]. The hydraulic oil supplied from the hydraulic pump 53 is supplied to the pipeline 61, the direction switching valve 41 and the flow control valve 4
2. Return to reservoir 54 via line 62. Further, the upper chamber 35 and the lower chamber 36 of the cylinder 31 of the connecting actuator 7 described above.
The hydraulic oil inside flows out to the reservoir 54 via the direction switching valve 41, the flow rate control valve 42, and the pipe line 62. Therefore, the piston 32 moves slidably, and the so-called free state in which the interval (stroke amount) between the front stabilizer bar 4 and the lower arm 6 constantly changes.

Further, when the direction switching valve 41 is in the contracted position 41b or the expanded position 41c, and the flow rate control valve 42 is duty ratio controlled so as to gradually reduce the opening degree from the communication position 42a to the cutoff position 42b, the operation is performed. The oil is connected to the actuator 7 via the hydraulic pump 53, the pipeline 61, the direction switching valve 41, and the port 35a.
Of the connecting actuator 7 through the upper chamber 35 of the upper chamber 35 or the port 36a, while the hydraulic oil inside the upper chamber 35 or the lower chamber 36 is supplied to the port 35a or the port 36a, respectively. , And flows out to the reservoir 54 via the direction switching valve 41 and the conduit 62. At this time, since the flow resistance of each flow passage changes according to the opening degree of the flow rate control valve 42 that is gradually closed, the flow rate of the hydraulic oil changes according to the flow resistance,
The moving speed of the piston 32 also changes. Therefore, the piston 33 of the coupling actuator 7 moves by the target stroke determined by the ECU 3, and is detected by the stroke sensor 24.
When the distance (stroke amount) between the left mounting portion of the front stabilizer bar 4 and the lower arm 6 becomes equal to the target stroke amount, a duty ratio control signal for keeping the opening of the flow control valve 42 constant is output. As a result, the connecting actuator 7 changes its entire length by the target stroke amount, and is in the extended state or the contracted state.
The hydraulic pressure generated by the throttle effect when the hydraulic oil supplied from the valve passes through the flow control valve 42 and the acting force applied to the connecting actuator 7 are held in balance. Therefore, the stabilizer bar 4 exerts a twisting action force, and rolling of the vehicle can be suppressed.

Next, the stabilizer control processing executed by the ECU 3 is executed in the fourth step.
This will be described based on the flowcharts shown in FIGS. (1), (2) and (3). This stabilizer control processing is executed when the ECU 3 is started. First, in step 100, a process of reading the vehicle speed V, the steering angle θ, and the lateral acceleration G1 is performed. In the following step 110, a process of calculating the estimated lateral acceleration G0 from the steering angle θ and the vehicle speed V read in the above step 100 according to the following equation (1) is performed.

G0 = h (θ, V) (1) However, the function h defines the relationship in which the power of the vehicle speed V is divided by the product of the steering angle θ and the constant α. Subsequent steps
At 120, the estimated lateral acceleration G0 calculated at step 110 is subjected to a filter operation to calculate a corrected estimated lateral acceleration G0F. This filter operation is generally
After the vehicle starts to turn and a predetermined delay time elapses, lateral acceleration corresponding to various conditions at the time of turning is generated, so that the estimated lateral value calculated by the time constant having a predetermined relationship with the delay time is generated. This is performed in order to calculate the corrected estimated lateral acceleration G0F by delay-correcting the generation time of the acceleration G0. Next, in step 130, the lateral acceleration G1 read in step 100 is read.
It is determined whether or not the absolute value of is greater than the lower limit lateral acceleration Kμ0. If an affirmative determination is made, the routine proceeds to step 140, and if a negative determination is made, the routine proceeds to step 150. Here, the lower limit lateral acceleration is a relatively small value close to zero, and the
It is to judge whether each operation of 140 and 250 is possible.
In step 140, which is executed when an affirmative determination is made in step 130, the lateral acceleration ratio G0F / G1 which is the value obtained by dividing the corrected estimated lateral acceleration G0F calculated in step 120 by the lateral acceleration G1 read in step 100 above. Is the lower limit lateral acceleration ratio K
It is determined whether or not μ1 is exceeded, and if a positive determination is made, the routine proceeds to step 250, while if a negative determination is made, the routine proceeds to step 150. Here, the lower limit lateral acceleration ratio Kμ1 is a constant value that is set to be able to determine whether or not the vehicle is traveling on a road surface having a high road surface friction coefficient, and is a relatively small value. Step 14 above
A negative judgment is made at 0, that is, step 150 executed when it is determined that the vehicle is traveling on a road surface having a high road friction coefficient.
Then, it is determined whether or not the snow flag FS is set to the value 1, and if the determination is affirmative, the process proceeds to step 250, and if the determination is negative, the process proceeds to step 160. Here, the snow flag FS is reset to a value of 0 during the normal active control of the stabilizer, and is set to a value of 1 when traveling on a snowy road (snow). Further, in step 160, it is determined whether or not the wet flag FW is set to the value 1, and if an affirmative determination is made, the process proceeds to step 250.
On the other hand, if a negative decision is made, the operation proceeds to step 170. Here, the wet flag FW is reset to a value 0 during the normal active control of the stabilizer, and is set to a value 1 when traveling on a wet road surface (wet). In step 170, which is executed when a positive determination is made in all of the above steps 150 and 160, it is considered that the vehicle is traveling on a road surface having a high friction coefficient, and the target stroke amount MS
Is calculated according to the following equation (2).

MS = f (V, θ) (2) where f is a predetermined function.

The target stroke amount MS is, for example, the lateral acceleration of the vehicle.
It may be calculated by multiplying G1 by a constant, or may be calculated, for example, according to a map created from the values calculated in advance for the vehicle speed V and the steering angle θ.
In the following step 180, the duty ratio D of the flow control valve 42
Is calculated according to the following equation (3).

D = g (MS) (3) where g is a function.

In the following step 190, processing for replacing the target stroke amount MS calculated in step 170 with the control stroke amount SG is performed. Next, the routine proceeds to step 200, where the current stroke amount S detected by the stroke sensor 24 is read. In the following step 210, it is determined whether or not the stroke amount S read in in the above step 200 is within a predetermined range (SG ± ΔSG) including the control stroke amount SG, and if a positive determination is made, it is necessary to adjust the stroke amount S. If not, step 240 is executed.
Proceed to. In step 220, which is executed when it is determined that the stroke amount S still needs to be adjusted, the control stroke amount determined by replacing the current stroke amount S with either step 190 or step 300 or 390 described later. A process of outputting a control signal for switching the directional control valve 41 to achieve SG is performed. In the following step 230, the calculation in step 180 described above, or step 30 described later
After performing the process of outputting the duty ratio control signal determined by replacement with 0,390 to the flow control valve 42, the above step 200
Return to. On the other hand, in step 240, which is executed when it is determined in step 210 that the stroke amount S does not need to be adjusted anymore, a process of outputting a duty ratio control signal for holding the opening degree of the flow control valve 42 is executed. After this, the present stabilizer control processing is temporarily terminated.

On the other hand, if the affirmative determination is made in step 140, that is, in step 250 executed when it is determined that the vehicle is traveling on a low friction coefficient road surface, the corrected estimated lateral acceleration G0F calculated in step 120 is used in the above steps. It is determined whether or not the lateral acceleration ratio G0F / G1, which is the value obtained by dividing the lateral acceleration G1 read by 100, exceeds the upper limit lateral acceleration ratio Kμ2. If an affirmative judgment is made, the routine proceeds to step 260, while a negative judgment is made. Then, it proceeds to step 340. Here, the upper limit lateral acceleration ratio Kμ2 is
It is a constant value set so that it can be determined whether the low friction coefficient road surface on which the vehicle is traveling is a snowy road surface or a wet road surface. When the affirmative judgment is made in the above step 250, that is, in step 260 which is executed while traveling on the snowy road, the processing of setting the snow flag FS to the value 1 is performed. In the following step 270, the target stroke amount MS calculated by the above step 170 is multiplied by a considerably small snow correction coefficient in the range of 0 to 1, and the target stroke amount MS is reduced.
The process of calculating 1 is performed. In the following step 280, the duty ratio D1 calculated in step 180 is multiplied by a snow correction coefficient having a considerably small value in the range of 0 to 1 to perform a reduction correction to calculate the duty ratio D1. Next, the routine proceeds to step 290, where it is determined whether or not the absolute value of the lateral acceleration G1 is less than the reference lateral acceleration Kμ3. If an affirmative judgment is made, the operation proceeds to step 310, while if a negative judgment is made, the operation goes to step 300. move on. Here, the reference lateral acceleration Kμ
3 is a comparatively small value corresponding to the lateral acceleration when the vehicle has shifted to a substantially straight traveling state. Step 29 above
At 0, when it is determined that the absolute value of the lateral acceleration G1 is equal to or greater than the reference lateral acceleration Kμ3, that is, when it is determined that the vehicle is turning on a snowy road, in step 300, in step 270 described above. After performing the process of replacing the calculated target stroke amount MS1 with the control stroke amount SG and the duty ratio D1 calculated in step 280 with the duty ratio D, the process proceeds to step 200 described above.

On the other hand, in step 310, which is executed when it is determined in step 290 that the absolute value of the lateral acceleration G1 is less than the reference lateral acceleration Kμ3, a process of resetting both the snow flag FS and the wet flag FW to the value 0. Is done. In the following step 320, a process of outputting a control signal for switching the direction switching valve 41 to the contracted position 41b or the expanded position 41c is performed. Next, in step 330, the flow control valve 42
After performing the process of outputting the duty ratio control signal that makes the switch fully open, this stabilizer control process is once ended.

In addition, in the case where the above step 250 is negatively determined, that is, in step 340 which is executed while traveling on a wet road surface (wet), it is determined whether or not the snow flag FS is set to the value 1, and a positive determination is made. And the above-mentioned step 260 assuming that the control during the snowy road traveling is still continued.
On the other hand, if a negative determination is made, the control during the wet road surface start is started, or the process proceeds to step 350 to continue, respectively, in step 350 executed during the wet road surface travel, the wet flag FW is set. The process of setting the value to 1 is performed. In the following step 360, the target stroke amount MS2 is calculated by reduction correction by multiplying the target stroke amount MS calculated in the above step 170 by a wet correction coefficient larger than the snow correction coefficient, which is small in the range of 0 to 1. Processing is performed. In the following step 370, the duty ratio D2 is calculated by decrement correction by multiplying the duty ratio D calculated in step 180 by a wet correction coefficient larger than the snow correction coefficient, which is small in the range of 0 to 1. Is done. Next, in step 380, it is determined whether or not the absolute value of the lateral acceleration G1 is less than the reference lateral acceleration Kμ3 described above.
On the other hand, if the result is negative, the process proceeds to step 390.
In step 390 executed when it is determined in step 380 that the absolute value of the lateral acceleration G1 is greater than or equal to the reference lateral acceleration Kμ3, that is, when it is determined that the vehicle is turning on a wet road surface, The target stroke amount MS2 calculated in step 360 is used as the control stroke amount SG and the above step 3
After the duty ratio D2 calculated in 70 is replaced with the duty ratio D, the process proceeds to step 200 described above. After that, the stabilizer control process repeats the above steps 100 to 390 at predetermined time intervals.

In the present embodiment, the hydraulic pressure source 8 and the connecting unit 10 serve as the twist amount adjusting means M1, and the vehicle speed sensor 21 serves as the vehicle speed detecting means M2.
The steering sensor 22 corresponds to the steering angle detecting means M3. The steps (170 to 240) of the ECU 3 and the processing executed by the ECU 3 function as the control means M4. Further, the lateral acceleration sensor 23 corresponds to the lateral acceleration detecting means M5, and the steps (110 to 120) of the ECU3 and the processing executed by the ECU3 serve as the estimated lateral acceleration calculating means M6, and the step (140,250) serves as the lateral acceleration ratio determination. As the means M7, the steps (270, 280, 360, 370) respectively function as the correction means M8.

As described above, according to the present embodiment, when the vehicle is traveling on a low friction coefficient road surface such as a snowy road or a wet road surface, the connection obtained from the vehicle speed and the steering angle when the road surface has a high friction coefficient is traveled. Since the active control execution of the stabilizer is performed using the control stroke amount obtained by correcting the target stroke amount of the unit 10, the occurrence of rolling, which is a harmful effect due to the over-control due to the active control execution of the stabilizer, occurs in advance. It can be prevented. Therefore, the occupant does not feel uncomfortable and the riding comfort is further enhanced.

In addition, for the purpose of controlling the vehicle attitude, it is possible to accurately understand which of the dry road surface with a high coefficient of friction, the snowy road surface with a low coefficient of friction, and the wet road surface. Since the control stroke amount suitable for the friction coefficient of is calculated and the active control of the stabilizer is executed, it is possible to suitably adapt to changes in the traveling road surface condition, and it is possible to realize active control of the stabilizer with high control accuracy and reliability.

Furthermore, when the active control of the stabilizer is executed, once the control corresponding to any of the dry road surface, the snowy road, and the wet road surface is started, the same control is performed until the absolute value of the lateral acceleration G1 becomes less than the reference lateral acceleration Kμ3. Since it is configured to continue, the control corresponding to the road surface having other characteristics is not started immediately with the sudden change of the road surface condition, so the control corresponding to the road surface having other characteristics (control stroke amount It is possible to suppress rolling of the vehicle caused by the rapid start of (with a large change).

In addition, even if it is determined that the vehicle has a low friction coefficient,
Since the active control of the stabilizer with the control amount reduced and corrected is continued, it is possible to avoid sudden changes in vehicle attitude as much as possible,
Maneuverability and stability are also improved.

Further, the estimated lateral acceleration G0F calculated from the vehicle speed and the steering angle is delayed by a time constant having a predetermined relationship with the delay time from the start of turning the vehicle to the occurrence of lateral acceleration to correct the estimated lateral acceleration G0F. The lateral acceleration ratio after that is calculated by performing a filter calculation for calculating the lateral acceleration ratio using the corrected estimated lateral acceleration G0F, so that the lateral acceleration that occurs after a lapse of a predetermined delay time from the start of turning of the vehicle is accurately calculated. You can
Road surface condition determination accuracy and control accuracy based on the determination are also improved.

In the present embodiment, the connecting actuator 7 is arranged only on the left front wheel side, but it is arranged, for example, on the left and right front wheels or on all four wheels, and each connecting actuator is controlled independently. You may. Even when such a configuration is adopted, the same effect as that of the above-described embodiment can be obtained.

In this embodiment, the ratio of the lateral acceleration G1 to the corrected estimated lateral acceleration G0F is compared with the upper and lower lateral acceleration ratios Kμ1 and Kμ2. However, conversely, the ratio of the corrected estimated lateral acceleration G0F to the lateral acceleration G1 may be compared with the upper limit and the lower limit lateral acceleration ratios KμX, KμY.

Further, in this embodiment, the low friction coefficient road surface is divided into two types, a snowy road and a wet road surface, and the control stroke amount of the snowy road and the wet road surface is a predetermined correction coefficient for the control stroke amount corresponding to the dry road surface. It is configured so that it is reduced and corrected only. However, for example, a low friction coefficient road surface is further divided into a large number to determine the control stroke amount, or the control stroke amount reduced and corrected according to a plurality of predetermined maps according to each road surface condition. A configuration for calculating, or a configuration for calculating a reduction-corrected control stroke amount adapted to each road surface by using an arithmetic expression including a parameter that accurately reflects the road surface condition such as a road surface friction coefficient in one of the variables, Even when the above is adopted, the same effect as that of the above-described embodiment can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the scope of the present invention. .

As described above in detail, the stabilizer control device of the present invention is
When the ratio of the estimated lateral acceleration calculated from the vehicle speed and the steering angle to the detected lateral acceleration exceeds a predetermined ratio, it is determined according to the vehicle speed and the steering angle that the vehicle is in a low friction coefficient road surface running state. The target amount of twist of the stabilized stabilizer is reduced and corrected. Therefore, when the vehicle speed detected by the vehicle speed detecting means or the steering angle detected by the steering angle detecting means does not accurately reflect the turning state of the vehicle due to the idling of the driving wheels or the skidding of the wheels, , The target twist amount of the stabilizer, which is determined according to the vehicle speed and the steering angle, is corrected to be decreased, and the twist amount of the stabilizer is prevented from being excessively controlled to a value larger than an appropriate value by continuing active control. This has an excellent effect of reliably preventing the occurrence of rolling due to.

When turning on a road surface with a low coefficient of friction, the target amount of twist of the stabilizer is reduced and corrected to an amount that matches the road surface with a low coefficient of friction, so that sudden changes in vehicle attitude are reduced as much as possible to improve maneuverability and stability. Can be prevented.

From each of the above-mentioned effects, without giving the occupant a feeling of strangeness,
Even though the ride quality is improved, significant advantages are obtained.

Further, during turning traveling on a dry road surface, normal active control of the stabilizer is executed, while during turning traveling on a low friction coefficient road surface, active control of the stabilizer is performed by a control amount reduced and corrected according to the road surface condition. So
There is also an advantage that it is possible to realize control that sufficiently considers the difference in the condition of the road surface on which the vehicle is turning, and to continue active control of the stabilizer with high control accuracy and reliability that can constantly suppress rolling satisfactorily.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the content of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, and FIG. 3 is an explanation showing a configuration of a hydraulic circuit and an electronic control unit thereof. FIGS. 4 (1), 4 (2) and 4 (3) are flowcharts showing the same control. M1 …… Twist amount adjusting means M2 …… Vehicle speed detecting means M3 …… Steering angle detecting means M4 …… Control means M5 …… Lateral acceleration detecting means M6 …… Estimated lateral acceleration calculating means M7 …… Lateral acceleration ratio judging means M8… Compensation means 1 Stabilizer control unit 3 Electronic control unit (ECU) 3a CPU 8 Hydraulic pressure source 10 Connection unit 21 Vehicle speed sensor 22 Steering sensor 23 Lateral acceleration sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Soga 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Hiroyuki Ikemoto 1, Toyota Town, Aichi Prefecture, Toyota Motor Corporation ( 72) Inventor Hidenori Ichimaru 1st Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP 62-74703 (JP, A) JP 60-191811 (JP, A)

Claims (1)

[Claims] 1. A twist amount adjusting means for adjusting a twist amount of a stabilizer connecting both unsprung members supporting left and right wheels of a vehicle according to a command from the outside, and a vehicle speed detecting means for detecting a vehicle speed of the vehicle. The steering angle detecting means for detecting the steering angle of the vehicle and the twist amount of the stabilizer are set to a target twist amount determined according to the vehicle speed detected by the vehicle speed detecting means and the steering angle detected by the steering angle detecting means. A stabilizer control device comprising: a control unit that outputs a command to change to the twist amount adjusting unit; and a lateral acceleration detecting unit that detects a lateral acceleration of the vehicle, and a vehicle speed detecting unit that detects the lateral acceleration. Estimated lateral acceleration calculating means for calculating the estimated lateral acceleration of the vehicle from the vehicle speed and the steering angle detected by the steering angle detecting means, and the estimation calculated by the estimated lateral acceleration calculating means. A lateral acceleration ratio determining means for determining whether or not the vehicle is in a low friction coefficient road surface running state in which the ratio of the lateral acceleration and the lateral acceleration detected by the lateral acceleration detecting means exceeds a predetermined ratio, and the lateral acceleration ratio determining means A stabilizer control device comprising: a correction unit that reduces and corrects the target twist amount determined by the control unit when it is determined to be in a low friction coefficient road surface running state.