JPH0853007A - Apparatus for controlling roll rigidity of vehicle and absolute steering angle detecting device suitably used therefor - Google Patents

Abstract

PURPOSE:To hold a satisfactory riding comfortableness of a vehicle even if a steering wheel is pivoted in straight travelling and hold the satisfactory steering stability of a vehicle even if the steering wheel in the turning is pivoted. CONSTITUTION:A microcomputer 24 calculates the steering speed of a steering wheel on the basis of the detected signal from a steering angle sensor 21 so as to change over shock absorbers 10A-10D to its hard condition when the steering speed gets higher. Also, the microcomputer 24 detects the rotational angle of the steering wheel from its neutral condition as the absolute steering angle so as to heighten the sensitivity of an attenuating force control as the absolute steering angle is increased. Thus, in the straight travelling of a vehicle the responsiveness of the attenuating force control in relation to the operation of the steering wheel is slowed down, while the responsiveness of the attenuating force control in relation to the operation of the steering wheel is speeded up in the turning of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a roll rigidity changing mechanism provided between a wheel and a vehicle body when a steering state amount which causes a roll of the vehicle body related to a steering operation of a steering wheel becomes large. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle roll rigidity control device for setting a high vehicle roll rigidity, and a vehicle absolute steering angle detection device suitable for use in the device.

[0002]

2. Description of the Related Art Conventionally, an apparatus of this type has been disclosed in, for example, Japanese Patent Publication Sho 6
As disclosed in Japanese Patent Application Laid-Open No. 2-47723, a steering speed of a steering wheel is detected as the steering state amount, and when the steering speed is increased, the roll rigidity of the vehicle is increased to suppress the roll of the vehicle during turning. To improve the controllability of the vehicle.

[0003]

However, in the above-mentioned conventional device, the roll rigidity of the vehicle is set high if the steering speed becomes higher than the predetermined speed regardless of the rotational position of the steering wheel. There is such a problem. That is, if the predetermined speed is set to an appropriate small value for starting to turn a vehicle traveling straight ahead, when the steering wheel of the turning vehicle is further turned, the vehicle body is already rolling. Therefore, the responsiveness of switching the roll rigidity is lacking, and the maneuverability of the vehicle deteriorates. On the other hand, if the predetermined speed is set to an appropriate large value for the case where the steering wheel of the vehicle that is turning is further rotated, when the steering wheel of the vehicle that is traveling straight ahead starts to rotate, the roll rigidity Since the switching response is too high, the riding comfort of the vehicle may be deteriorated. The present invention has been made to solve the above problems, and an object of the present invention is to prevent the comfort of the vehicle from deteriorating even when the steering wheel of the vehicle traveling straight ahead starts to rotate, and to prevent the vehicle from turning. It is an object of the present invention to provide a roll rigidity control device for a vehicle, which maintains good steering stability even when the steering wheel is further rotated.

[0004]

In order to achieve the above-mentioned object, the first structural feature of the present invention is that when the steering state quantity that causes the rolling of the vehicle body is increased in relation to the steering operation of the steering wheel, In the roll rigidity control device that increases the roll rigidity of the vehicle, the rotation angle from the neutral state of the steering wheel that corresponds to the straight running state of the vehicle is detected as the absolute steering angle, and the control sensitivity for switching the roll rigidity as the absolute steering angle increases. Is to make it higher.

The second feature is that in the roll rigidity control device having the first feature, the relative steering angle detecting means for detecting the rotation angle from the arbitrary rotation position of the handle as the relative steering angle, and the handle A neutral signal generating means for generating a neutral signal when the rotational position is in the neutral position, and a wheel speed detecting means for detecting each wheel speed of the left and right wheels are provided, and each of the detected signals is generated when the neutral signal is generated. The wheel speed difference is at least 360 from the neutral state of the steering wheel.
The detected relative steering angle is determined as a zero-point correction value on the condition that the rotation angle is less than 10 degrees, and the absolute steering angle is calculated by the detected relative steering angle and the determined zero-point correction value. I have done so.

A third feature is that instead of determining the zero point correction value of the second feature, the difference between the detected wheel speeds when the neutral signal is generated causes the steering wheel to detect the difference. The detected relative steering angle is determined as a zero point correction value on the condition that the vicinity of the neutral state is shown, and when the neutral signal is generated, the difference between the wheel speeds is 360 degrees from the neutral state of the steering wheel. The detected relative steering angle is set to 36
The value obtained by adding or subtracting 0 degrees is determined as the zero point correction value.

A fourth feature is provided with a relative steering angle detecting means and a wheel speed detecting means similar to the second feature, and estimates an absolute steering angle based on the detected difference between the wheel speeds. Calculating a zero point correction value of the relative steering angle based on the detected relative steering angle and the estimated absolute steering angle, and calculating the absolute steering angle based on the detected relative steering angle and the calculated zero point correction value. I have done so.

A fifth feature is that the relative steering angle detecting means and the wheel speed detecting means similar to those of the second feature are provided, and the change in the detected relative steering angle is small for a predetermined time continuously and When the difference between the detected wheel speeds is small, the detected relative steering angle is determined as a zero point correction value, and the absolute steering angle is calculated by the detected relative steering angle and the determined zero point correction value. There is something I did.

A sixth feature is that the vehicle absolute steering angle detecting device for detecting the absolute steering angle from the neutral state of the steering wheel generates a rotation signal corresponding to the rotation of the steering wheel at each minute angle and the steering wheel. A steering angle sensor that generates a neutral signal when the vehicle is in a neutral state corresponding to the straight traveling state of the vehicle, and a rotation angle from an arbitrary rotation position of the steering wheel is detected as a relative steering angle according to a rotation signal from the steering angle sensor. A relative steering angle detection means and a wheel speed detection means for detecting each wheel speed of the left and right wheels respectively are provided, and the difference between the detected wheel speeds when the neutral signal is generated is from the neutral state of the steering wheel. The detected relative steering angle is determined as a zero point correction value on the condition that it is substantially smaller than the rotation angle of at least less than 360 degrees, and the detected relative steering angle and the determined zero point compensation value. The value in that so as to calculate the absolute steering angle.

Further, a seventh feature is that the steering angle sensor generates a rotation signal corresponding to the rotation of the steering wheel at each minute angle and the steering wheel is in a neutral state corresponding to the straight traveling state of the vehicle and from the neutral state. Instead of determining the neutral point signal of the sixth characteristic when the neutral signal is generated, the detected neutral signal is generated when the neutral signal is generated. The detected relative steering angle is determined as a zero-point correction value on condition that the difference in wheel speed indicates the vicinity of the neutral state of the steering wheel, and the difference between the wheel speeds when the neutral signal is generated. Is determined to be a value obtained by adding or subtracting 360 degrees to the detected relative steering angle on condition that the steering wheel is in the vicinity of a state where the steering wheel is rotated 360 degrees from the neutral state. Lies in the fact was Unishi.

[0011]

According to the first feature of the present invention configured as described above, the roll stiffness switching control of the vehicle is controlled as the absolute steering angle as the rotation angle from the neutral state of the steering wheel increases. Since the sensitivity has been increased, the responsiveness to the roll stiffness switching of the vehicle does not become unnecessarily high when the steering wheel of the vehicle running straight ahead starts to rotate, and the riding comfort of the vehicle is improved. Keeps good. Further, when the steering wheel of the vehicle during turning is further rotated, the responsiveness to the switching of the roll rigidity of the vehicle becomes high, and the steering stability of the vehicle is kept good.

Further, according to the second feature, when the neutral signal indicating that the steering wheel is in the neutral state corresponding to the straight traveling state of the vehicle is generated, the difference between the wheel speeds of the left and right wheels is neutral. Since the relative steering angle is determined as the zero point correction value on the condition that the rotation angle is at least less than 360 degrees from the state, the absolute steering angle is calculated from the relative steering angle and the zero point correction value. The relative steering angle is determined as the zero-point correction value while avoiding the state where the steering wheel makes one rotation or more and the neutral signal is generated. Therefore, the zero-point correction value is accurately determined, and the absolute steering angle calculated based on the zero-point correction value is also highly accurate, which in turn improves the roll rigidity control accuracy according to the first feature.

Further, according to the third feature, when the steering wheel is in the neutral state or the steering wheel is rotated 360 degrees from the neutral state and the neutral signal is generated from the steering angle sensor, The relative steering angle is determined as a zero-point correction value on condition that the difference indicates the vicinity of the neutral state of the steering wheel, and the difference between the wheel speeds indicates the vicinity of a state in which the steering wheel is rotated 360 degrees from the neutral state. Under this condition, the value obtained by adding or subtracting 360 degrees to the relative steering angle is determined as the zero point correction value. Therefore, the zero point correction value is determined even if the steering wheel is rotated one or more times from the neutral state. Therefore, in addition to the effect of the second feature, the absolute steering angle can be calculated widely and promptly even under the traveling condition of the vehicle such as when the vehicle is turning with a small radius.

According to the fourth feature, the absolute steering angle is estimated based on the wheel speeds of the left and right wheels, and the relative steering angle is corrected to the zero point by the detected relative steering angle and the estimated absolute steering angle. Since the absolute steering angle is calculated by calculating the value and the detected relative steering angle and the determined zero point correction value, the zero point correction value can be calculated without using the neutral signal, and the first The absolute steering angle required for the feature can be detected with a simple configuration.

Further, according to the fifth feature, a small difference between the wheel speeds of the left and right wheels means that the vehicle is in a substantially straight traveling state, and further, the change in the relative steering angle is small for a predetermined time continuously. This assures that the vehicle continues straight ahead. Since the zero point correction value is determined as the relative steering angle when the vehicle is in a straight traveling state, the relative steering angle can be converted to the absolute steering angle by only calculating the left and right wheel speeds and calculating the rest. The absolute steering angle required for the first feature can be detected with a simple configuration.

Further, according to the sixth feature, the zero-point correction value and the absolute steering angle are calculated with high accuracy for the same reason as the second feature. Further, according to the seventh feature, for the same reason as the third feature, the wide zero point correction value and the absolute steering angle are calculated even while the vehicle is turning. And
The absolute steering angle calculated in this way is used not only for the roll rigidity of the vehicle but also for the behavior control of the vehicle other than the roll rigidity, and the traveling state of the vehicle can be satisfactorily corrected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 conceptually shows shock absorbers 10A to 10D as a roll rigidity changing mechanism of a vehicle according to the present invention, and the absorbers 10A to 10D. A block diagram of an electrical control unit 20 for controlling the 10D is shown.

The shock absorbers 10A to 10D are respectively arranged between the left and right front wheels and the left and right rear wheels, more specifically, between a lower arm (unsprung member) connected to each wheel and a vehicle body (sprung member). Each shock absorber 10A ~
Reference numeral 10D includes hydraulic cylinders 12a to 12d that are partitioned into upper and lower chambers by pistons 11a to 11d, and the cylinders 12a to 12d are supported by lower arms, respectively. The piston rod 1 is attached to the pistons 11a to 11d.
3a to 13d are respectively connected at the lower ends, and the same rod 1
3a to 13d respectively support the vehicle body at the upper end.
The upper and lower chambers of the hydraulic cylinders 12a to 12d are electromagnetic valves 1
4a to 14d are in communication with each other, and the valves 14a to
The shock absorbers 10A to 10A depending on the opening degree of 14d.
The damping force of D can be switched between soft and hard, that is, the roll rigidity of the vehicle can be switched between high and low. Each of the lower chambers of the hydraulic cylinders 12a to 12d has a gas spring unit 15a to 1a for absorbing a volume change of the upper and lower chambers due to the vertical movement of the piston rods 13a to 13d.
5d are respectively connected.

The electric control unit 20 includes a steering angle sensor 21 and left and right wheel speed sensors 22 and 23. The steering angle sensor 21 is, as shown in FIG. 2, an optical device 21b fixed to a stationary member that constitutes a case of a rotary disk 21a and a coaxial 31 that is fixed to a steering shaft 31 connected to a steering wheel 30.
Consists of The turntable 21a is provided with a large number of slits 21a1 arranged at short constant intervals along the circumferential direction, and a slit 21a2 provided at only one inside thereof. The optical device 21b is installed at a position facing the slit 21a2 when the steering wheel 30 is in a neutral state corresponding to a straight traveling state of the vehicle and a position rotated 360 degrees from the neutral state. A pair of light receiving elements 21b1 and 21b2 facing the slit 21a1 and having a 1/4 interval of the pitch of the slit 21a1 and a light receiving element 21b3 arranged inside thereof. ing. The light emitting elements 21b1 and 21b2 have a two-phase rotation signal SS as shown in FIG.
1 and SS2 are output, and the center signal SSC is output for each rotation of the handle 30. Left and right wheel speed sensor 2
Reference numerals 2 and 23 respectively detect the wheel speeds Vwl and Vwr of the left and right front wheels or the left and right rear wheels (preferably driven wheels that are not affected by driving slip), and output detection signals representing the wheel speeds Vwl and Vwr.

The steering angle sensor 21 and the left and right wheel speed sensors 22 and 23 are respectively provided in the microcomputer 2.
4 is connected. The microcomputer 24 repeatedly executes a program corresponding to the flowcharts shown in FIGS. 4 to 6 every predetermined short time under the control of the built-in timer circuit. Further, the absolute steering angle θ * and the steering speed dθ * / dt shown in FIG.
A damping force table that defines the control region of the damping force of the shock absorbers 10A to 10D is prepared as an axis, and a steering angle table that stores the absolute steering angle θv that changes according to the change in the wheel speed difference Vw2 of the left and right wheels is prepared. Has been done. The microcomputer 24 includes a drive circuit 2 corresponding to each shock absorber 10A to 10D.
5a to 25d are connected to each drive circuit 25a to 2d.
In response to a control signal from the microcomputer 24, 5d switches the opening of each of the electromagnetic valves 14a to 14d to switch the absorbers 10A to 10D to a soft state or a hard state.

Next, the operation of the embodiment configured as described above will be described. When the ignition switch is turned on, the microcomputer 24 executes an initial setting process (not shown), and then steps 100 to 122 of FIG. 4 every predetermined time.
The damping force control program consisting of is repeatedly executed. In the initial setting process, the initial state flag IF and the relative steering angle θ are both set to “0”, and the control signals representing the soft states of the shock absorbers 10A to 10D are output to the drive circuits 25a to 25d. Drive circuit 25
The a to 25d store the supplied control signal, and control the opening of the electromagnetic valves 14a to 14d based on the stored control signal to set the damping force of the shock absorbers 10A to 10D to the soft state. In the program of FIG. 4, the relative steering angle calculation routine is executed in step 102, and the zero point correction value calculation routine is executed in step 104.

The details of the relative steering angle calculation routine are shown in FIG. 5, the execution of which is started in step 200,
In step 202, the two-phase rotation signals SS1 and SS2 are input from the steering angle sensor 21. Next, in step 204, the previous two-phase data (SS1, SS2) is replaced with the current two-phase data (SS1, SS2)
Updated to the current two-phase data (SS1, SS
2) is updated to a value representing the input two-phase rotation signals SS1 and SS2. The previous two-phase data (SS1, SS2) is the two-phase rotation signal SS when the previous relative steering angle calculation routine was executed.
1, SS2, and the current two-phase data (SS1, SS2) represent the two-phase rotation signals SS1, SS2 during execution of the relative steering angle calculation routine this time.

After updating the previous two-phase data (SS1, SS2) and the current two-phase data (SS1, SS2), steps 208 to 2
If the rotational positions of the steering wheel 30 and the turntable 21a are the same as those at the time of executing the relative steering angle calculation routine of the previous time by the processing of 16, the rotation amount θ of the steering wheel 30 at step 218.
Set m to "0". For example, as shown in FIG. 3, the previous two-phase data (SS1, SS2) is “00” and the current two-phase data is 2
If the phase data (SS1, SS2) is also "00", step 20
The program is step 218 by the processing of 8 and 210.
Then, the process of step 218 is executed. If the rotational positions of the steering wheel 30 and the turntable 21a have changed to the right since the previous execution of the relative steering angle calculation routine, the rotation amount θm of the steering wheel 30 corresponds to the interval of the slit 21a1 in step 220. Set to a positive rotation angle θa. For example, as shown in Fig. 3, the previous two-phase data (SS
1, SS2) is “01” and this time the two-phase data (SS1, SS
If 2) is "00", the program proceeds to step 220 and the processing of step 220 is executed by the processing of steps 208 and 212. If the rotational positions of the steering wheel 30 and the turntable 21a have changed to the left since the previous execution of the relative steering angle calculation routine, step 222 is performed.
The rotation amount θm of the handle 30 is set to a negative rotation angle −θa. For example, as shown in Fig. 3, the previous two-phase data (SS
1, SS2) is “10” and this time the two-phase data (SS1, SS
If 2) is "00", the program proceeds to step 222 by the processing of steps 208 and 214, and the processing of step 222 is executed.

Further, even when the rotation directions of the handle 30 and the turntable 21a are unknown, the rotation amount θm of the handle 30 is set to "0" in step 218. For example,
As shown in Fig. 3, the previous two-phase data (SS1, SS2) is "1".
1 ", and the two-phase data (SS1, SS2) this time is" 00 "
If so, the program proceeds to step 218 by the processing of steps 208 and 216 to execute the processing of step 218. If the execution frequency of this relative steering angle calculation routine is increased with respect to the rotation speed of the steering wheel 30,
It is possible to avoid the situation where the rotation direction is unknown as described above. Next, at step 224, the rotation amount θm set by the processing at steps 218 to 222 is added to the relative steering angle θ of the steering wheel 30 to update the relative steering angle θ according to the rotation of the steering wheel 30.

The details of the zero correction value calculation routine are shown in FIG. 6, the execution of which is started in step 300.
In step 302, the detection signals representing the left and right wheel speeds Vwl and Vwr are input from the left and right wheel speed sensors 22 and 23, respectively. Next, at step 304, it is judged if the center signal SSC is generated from the steering angle sensor 21. If the center signal SSC is generated, it is determined to be "YES" at step 304 and the program is advanced to step 306. In step 306, the left and right wheel speeds Vwl, V
The left / right wheel speed difference ΔVw1 = | Vwl−Vwr | is calculated based on wr.

Next, in step 308, the left / right wheel speed difference ΔVw1 calculated above is a predetermined value Vth representing the left / right wheel speed difference corresponding to a small rotation angle of the steering wheel 30 of about half a rotation.
(See FIG. 3) It is determined whether or not the difference is equal to or less than the above, and the same left and right wheel speed difference Δ
If Vw1 is equal to or less than the predetermined value Vth, the zero correction value θo for the relative steering angle θ is set to the current relative steering angle θ in step 310 based on the determination of “YES” in step 308. In this case, the fact that the left / right wheel speed difference ΔVw1 is less than or equal to the predetermined value Vth means that the rotation of the steering wheel 30 is within about 180 degrees to the left / right (the steering wheel 30 is in the vicinity of the neutral state), and the steering angle sensor 21. Since the center signal SSC is generated from this means that the rotating position of the turntable 21a is neutral (see FIG. 3), in this state, the steering wheel 30 is in the neutral state corresponding to the straight traveling state of the vehicle. become. Therefore, the zero correction value θo represents the amount of deviation from the neutral state of the relative steering angle θ that changes with time.

Further, the left and right wheel speed difference ΔVw1 is a predetermined value Vth.
If it is larger, it is determined to be “NO” in step 308 and the program proceeds to step 312. Step 31
In 2, the left wheel speed Vwl and the right wheel speed Vwr are compared to determine whether or not the vehicle is making a right turn. If the vehicle is making a right turn, it is determined to be "YES" in step 312, and the zero correction value θo is set to a value obtained by subtracting 360 degrees from the current relative steering angle θ in step 314. If the vehicle is making a left turn, it is determined to be "NO" in step 312 and the zero correction value θo is set to the current relative steering angle θ in step 316.
Is set to a value obtained by adding 360 degrees to. In this case, the fact that the left-right wheel speed difference ΔVw1 is larger than the predetermined value Vth means that the steering wheel 30 is rotated 180 degrees or more to the right or left (the steering wheel 30 is in the vicinity of the state where the steering wheel 30 has been rotated about 360 degrees from the neutral state). In addition, the fact that the center signal SSC is generated from the steering angle sensor 21 means that the rotating position of the turntable 21a is in the neutral position (see FIG. 3). It is only rotating once. The left wheel speed Vwl is greater than the right wheel speed Vwr when the vehicle is turning right, and the right wheel speed Vwr is greater than the left wheel speed Vwl when the vehicle is turning left. It represents the amount of deviation from the neutral state of the changing relative steering angle θ. The handle 30
Shall not rotate more than 2 turns left and right.

On the other hand, if the center signal SSC from the steering angle sensor 21 is not generated at the time of the determination processing of step 304, it is determined to be "NO" in step 304 and the program proceeds to step 318. In step 318, it is determined whether or not the initial state flag IF set to "0" by the initial setting process is "1". Immediately after the program is started and the flag IF is "0",
In step 318, the determination is “NO”, and the program proceeds to steps 320 to 324. In step 320, the wheel speed difference ΔVw2 is calculated based on the left and right wheel speeds Vwl and Vwr.
Calculate (= Vwr-Vwl). In step 320, the corrected steering angle θv corresponding to the calculated wheel speed difference ΔVw2 is derived with reference to the steering angle table of FIG. In step 324, the corrected steering angle θv is added to the relative steering angle θ, and the addition result is set as the zero point correction value θo.

This is based on the fact that the wheel speed difference ΔVw2 has a substantially constant relationship (proportional relationship) with the absolute steering angle from the neutral state of the steering wheel 30. And the right wheel speed Vwr
The value obtained by subtracting the left wheel speed Vwl from is defined as the wheel speed difference ΔVw2,
In addition, since the corrected steering angle θv is approximately directly proportional to the wheel speed difference ΔVw2, the corrected steering angle θv represents the absolute steering angle when the vehicle turns left and the absolute steering angle when the vehicle turns right. The angle is shown as negative. On the other hand, the absolute neutral state is
When the vehicle is turning left, it is in the right rotation direction (forward direction) by the absolute steering angle from the relative steering angle θ, and when the vehicle is turning right, it is the left rotation direction (positive direction) by the absolute steering angle from the relative steering angle θ. Negative direction). Therefore, in step 32
The zero-point correction value θo calculated by the addition operation of 4 represents the amount of deviation of the relative steering angle θ that changes with time from the absolute neutral position.

After the processing of steps 314, 316 and 324, the initial state flag IF is set to "1" in step 326, and the execution of the zero point correction value calculation routine is ended in step 328. Therefore, in the second and subsequent zero-point correction value calculation routines, if the center signal SSC is present from the steering angle sensor 21, it is determined to be “YES” in step 304 and the zero-point correction value θo is determined in steps 306 to 316. Will be updated. However, when the center signal SSC does not exist from the steering angle sensor 21, it is determined to be “NO” in step 304 and “NO” in step 318, and steps 320 to 32 are performed.
Since the program proceeds to step 326 without executing the processing of No. 4, the zero correction value θo is not updated.

After executing the relative steering angle calculation routine and the zero point correction value calculation routine, the microcomputer 24 subtracts the zero point correction value θo from the relative steering angle θ in step 106 of FIG. 4 to perform absolute steering of the steering wheel 30. Calculate the angle θ *. Next, in steps 108 and 110, the previous absolute steering angle θ * old is updated to the current absolute steering angle θ * new, and the current absolute steering angle θ * new is updated to the calculated absolute steering angle θ *. The previous absolute steering angle θ * old represents the absolute steering angle θ * when the damping force control program was executed last time, and the current absolute steering angle θ * new is the absolute steering angle θ * when the damping force control program was executed this time. Represent After updating the previous absolute steering angle θ * old and the current absolute steering angle θ * new,
In step 112, the value obtained by subtracting the previous absolute steering angle θ * old from the current absolute steering angle θ * new is divided by the value Δt representing the short time corresponding to the execution cycle of this damping force control program,
The change speed of the absolute steering angle θ * (equal to the change speed of the relative steering angle θ), that is, the steering speed dθ * / dt is calculated.

After the processing of step 112, step 1
The damping force table (FIG. 7) is referenced at 14 to determine the region to which the state determined by the combination of the absolute steering angle θ * and the steering speed dθ * / dt belongs. If the state does not belong to the area A,
The microcomputer 24 proceeds to step 116
"O", and in step 118, drive circuits 25a-2
A control signal indicating the soft state is output to 5d. Therefore, in this case, the shock absorbers 10A to 10D
The damping force of is set low, and the ride comfort of the vehicle is maintained good. On the other hand, if the state belongs to the area A, the microcomputer 24 determines “YES” in step 116 and outputs a control signal representing the hard state to the drive circuits 25a to 25d in step 120. Therefore, in this case, the damping force of the shock absorbers 10A to 10D is set to be high, the roll of the vehicle body is suppressed, and the steerability of the vehicle is kept good.

As can be understood from the above description of the operation, according to the above-described embodiment, as the absolute value | θ * | of the absolute steering angle θ * increases, the absolute steering angle θ * and the steering speed dθ
The state determined by the combination of * / dt belongs to the area A even if the steering speed dθ * / dt is small. This means that the control sensitivity for increasing the damping force of the vehicle body, that is, the roll rigidity, increases as the absolute steering angle θ * increases. Therefore, when the steering wheel of the vehicle traveling straight ahead is turned, the responsiveness to the switching of the roll rigidity of the vehicle does not become unnecessarily fast,
The ride comfort of the vehicle is kept good. Further, when the steering wheel of the vehicle being turned is rotated, the responsiveness to the switching of the roll rigidity of the vehicle becomes faster, and the steering stability of the vehicle is kept good.

According to the above embodiment, the relative steering angle θ is detected from the steering angle sensor 21 based on the two-phase rotation signals SS1 and SS2 by executing the relative steering angle calculation routine shown in FIG. By executing the correction value calculation routine, the zero correction value θo is calculated based on the relative steering angle θ, the left and right wheel speeds Vwl and Vwr detected by the left and right wheel speed sensors 22 and 23, and the center signal SSC of the steering angle sensor 21. Four
The absolute steering angle θ * is calculated based on the zero-point correction value θo and the relative steering angle θ by the processing of step 106. Then, in the zero point correction value calculation routine,
If the center signal SSC from the steering angle sensor 21 is present, the zero point correction value θo is calculated by the processing of steps 306 to 316 in FIG. 6, and if the center signal SSC is not present, the processing is performed in steps 320 to 324 of FIG. Calculate the zero correction value θo. Therefore, the absolute steering angle θ * can be detected easily and accurately without delay.

In the zero point correction value calculation routine of FIG. 6 of the above embodiment, the steps 304 to 316 using the center signal SSC from the steering angle sensor 21 and the steps 320 to 324 not using the center signal SSC are executed. Although the zero point correction value θo is calculated by the combined use of the processes, the zero point correction value θo may be detected by using the processes of steps 304 to 316 and steps 320 to 324 independently. In this case, steps 304 to 3
When the zero point correction value θo is calculated by the independent processing of 16, the zero point correction value θo is generated until the center signal SSC is generated.
Can not be calculated, but this time is usually small, so
It is sufficient to ignore this time and not calculate the absolute steering angle θ *, or interrupt the control using the same absolute steering angle θ *. Further, when the zero point correction value θo is calculated by the independent processing of steps 320 to 324, the center signal SSC is not used, so the zero point correction value θo can be easily calculated and the absolute steering angle θ * can be calculated.

Further, the zero point correction value may be detected only by the processing of steps 304 to 310 in the processing of steps 304 to 316, that is, only when the handle 30 is in the neutral state. According to this, when the handle 30 is rotated 360 degrees or more, it is ignored. Therefore, the predetermined value Vth in the determination process of step 308 represents a rotation angle of the handle 30 that is at least less than 360 degrees from the neutral state. Good.

Next, a modification of the zero point correction value calculation routine (details shown in FIG. 6) executed in step 102 of FIG. 4 will be described. The zero point correction value calculation routine according to the modification example is shown in FIG. Shown in detail. Execution of this routine begins at step 350 and proceeds to step 352.
In the same manner as in the above embodiment, the respective detection signals representing the left and right wheel speeds Vwl and Vwr are input, and in step 354, the absolute value | Vwl-Vwr | The value is set as the wheel speed difference ΔVw.

Next, in step 356, the calculated wheel speed difference ΔVw is compared with a predetermined small value Vth to determine whether the wheel speed difference ΔVw is equal to or less than the predetermined value Vth.
This determination process is performed to determine whether or not the vehicle is traveling substantially straight. If the wheel speed difference ΔVw is less than or equal to the predetermined value Vth, it is determined to be “YES” in step 356 and the program proceeds to step 358 and thereafter. On the other hand, if the wheel speed difference ΔVw is larger than the predetermined value Vth, step 356.
In step 372, the timer circuit built in the microcomputer 24 is cleared,
In step 374, the execution of this zero-point correction value calculation routine ends.

In step 358, the previous relative steering angle θ _N-1 is updated to the current relative steering angle θ _N , and in step 360, the current relative steering angle θ _N is calculated in step 102 of FIG. To update. Here, the previous relative steering angle θ _N-1 represents the relative steering angle θ calculated during the execution of the previous damping force control program (FIG. 4), and the current relative steering angle θ _N during the execution of the present damping force control program. It represents the calculated relative steering angle θ. After updating these previous relative steering angle θ _N-1 and this time relative steering angle θ _N , at step 362 the absolute value of the difference between the previous relative steering angle θ _N-1 and this time relative steering angle θ _N |
θ _N −θ _N-1 | is calculated and the calculated result is used as the steering angle difference Δθ _N
Set as. Next, at step 364, the steering angle difference Δ
By comparing θ _N with a predetermined small value θ th, the steering angle difference Δθ _N
Is below a predetermined value θth. This determination processing determines that the change in the relative steering angle θ is minute, that is, that the steering operation of the steering wheel 30 is not performed.

If the steering angle difference Δθ _N is less than or equal to the predetermined value θth, it is determined to be "YES" at step 364, the timer value of the timer circuit is incremented at step 366, and the program proceeds to step 368. On the other hand, if the steering angle difference Δθ _N is larger than the predetermined value θth, step 3
When it is determined to be "NO" at 64, the timer circuit is cleared at step 372, and the execution of this zero-point correction value calculation routine is ended at step 374. In step 368, it is determined whether the incremented timer value of the timer circuit is equal to or greater than a predetermined value. In this case, if the timer value does not reach the predetermined value, it is determined to be "NO" in step 368, and the execution of this zero point correction value calculation routine is ended in step 374. On the other hand, when the timer value resulting from the increment in step 366 becomes equal to or greater than the predetermined value, it is determined to be “YES” in step 368, and the zero correction value θo is set to the current relative steering angle θ in step 370.
Is set, and the execution of this zero-point correction value calculation routine is ended in step 374.

According to this modification, the fact that the wheel speed difference ΔVw is small and is equal to or smaller than the predetermined value Vth means that the vehicle is in a substantially straight traveling state, and the steering angle difference Δθ _N is longer than the predetermined time. Being equal to or smaller than the predetermined value θth further guarantees that the straight traveling state of the vehicle continues. Since the zero point correction value θo is determined as the relative steering angle θ in a straight traveling state, the left and right wheel speeds Vwl, Vwr and the relative steering angle θ can be detected and the rest can be calculated. The zero point correction value θ
o can be detected with a simple configuration. In addition, this zero correction value θo
By using, the absolute steering angle θ * can be calculated by the process of step 106 of FIG. 4 of the above embodiment, so that the steering angle θ * can also be easily detected.

Further, the absolute steering angle detecting portion according to the above embodiment and the various modifications, that is, the steering angle sensor 21, the left and right wheel speed sensors 22 and 23, the relative steering angle calculation routine of FIG. 5, and FIG. 6 (or FIG. 9). If the zero-point correction value calculation routine of 4) and the process of step 106 of FIG. 4 are separated as a single absolute steering angle detecting device, the detected absolute steering angle can be used for behavior control of various vehicles other than roll rigidity control.

Next, step 114 in FIG. 4 of the above embodiment.
A modified example in which the vehicle speed is also taken into consideration in the area determined in 1 will be described. In this case, the microcomputer 24 executes the processes of steps 113 and 114a of FIG. 10 instead of the process of step 114 of FIG. 4, and replaces the damping force table of FIG. 7 with the vehicle speed V as shown in FIG.
The damping force table has a characteristic in which the boundary line approaches the origin O by increasing.

In the modified example configured as above, the average value of the sum of the wheel speeds Vwl and Vwr of the left and right wheels is calculated as the vehicle speed V in step 113 of FIG. 10 after the processing of steps 102 to 112 of FIG. Then, in step 114a, it is determined whether or not the state determined by the absolute steering angle θ * and the steering speed dθ * / dt belongs to the area A that changes according to the vehicle speed V.
The processing after the processing of step 114a is the same as that in the above embodiment. According to this, since the boundary line of the area A approaches the origin O as the vehicle speed V increases, the damping forces of the shock absorbers 10A to 10D are easily switched to the hard state, and the maneuverability during high-speed traveling is good. Becomes

Further, in the above embodiment, when the damping force of the shock absorbers 10A to 10D is switched to the hard state or the soft state, the holding time for holding the switched state is not provided. However, in order to avoid frequent switching of the damping force, the switching of the damping force to the hard state or the soft state once may be prohibited again after a predetermined time has elapsed.

Further, in the above embodiment, the handle 3
Although the steering speed dθ * / dt of the steering wheel 30 is adopted as the steering state amount that causes the roll of the vehicle body in relation to the steering operation of 0, the absolute steering angle θ * is larger than the steering speed dθ * / dt. The steering speed dθ *
A physical quantity considering both / dt and the absolute steering angle θ *, for example, a weighted sum of the two may be adopted as the steering state quantity.

Further, in the above embodiment, the damping force of the shock absorbers 10A to 10D is switched to two stages of the soft state and the hard state. However, the damping force of the absorbers 10A to 10D is divided into a plurality of stages of three stages or more. You may switch to. In this case, step 1 of FIG.
At 20, the shock absorbers 10A to 10D increase as the steering speed dθ * / dt or the absolute steering angle θ * increases.
The damping force of 1 may be largely switched to the hard side.

Further, in the above embodiment, the damping force variable type shock absorber is used as the roll rigidity changing mechanism, and the damping force characteristic is switched as the roll rigidity is switched. However, the roll rigidity changing mechanism may be a spring force variable type stabilizer, a spring force variable type fluid spring formed by enclosing a fluid instead of a coil spring, and the like. The roll rigidity of may be switched.
Alternatively, the roll rigidity may be switched by changing the damping force generated in the fluid pressure cylinder of the fluid pressure type active suspension.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a shock absorber and an electric control device for the shock absorber according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an assembled state of the steering angle sensor of FIG.

FIG. 3 is a diagram showing a relationship between various detection signals output from the steering angle sensor and left and right wheel speed differences.

FIG. 4 is a flowchart corresponding to a damping force program executed by the microcomputer of FIG.

5 is a detailed flowchart of a relative steering angle calculation routine of FIG.

FIG. 6 is a detailed flowchart of a zero-point correction value calculation routine of FIG.

7 is a characteristic diagram of data in a damping force table provided in the microcomputer of FIG.

8 is a characteristic diagram of data in a steering angle table provided in the microcomputer of FIG.

FIG. 9 is a detailed flowchart of a zero point correction value calculation routine according to a modified example.

FIG. 10 is a flowchart showing a part of a damping force program according to a modification.

FIG. 11 is a characteristic diagram of data in a damping force table according to a modification.

[Explanation of symbols]

10A to 10D ... Shock absorbers, 12a to 12d
... hydraulic cylinders, 14a to 14d ... electromagnetic valves, 20 ...
Electric control device, 21 ... Steering angle sensor, 22, 23 ... Wheel speed sensor, 24 ... Microcomputer.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B62D 113: 00

Claims (7)

[Claims] 1. A control device for controlling a roll rigidity changing mechanism, which is provided between a wheel and a vehicle body and is capable of changing the roll rigidity of the vehicle, and is a cause of roll of the vehicle body related to steering operation of a steering wheel. The steering state amount detecting means for detecting the steering state amount and the switching control means for controlling the roll rigidity changing mechanism to switch the roll rigidity of the vehicle to the higher side when the detected steering state amount becomes large. In a roll rigidity control device, an absolute steering angle detecting means for detecting a rotation angle from a neutral state of a steering wheel corresponding to a straight traveling state of a vehicle as an absolute steering angle, and the switching control means as the detected absolute steering angle increases. A roll rigidity control device for a vehicle, comprising: sensitivity control means for increasing control sensitivity for switching roll rigidity by means of. 2. The absolute steering angle detection means according to claim 1, a relative steering angle detection means for detecting a rotation angle of a steering wheel from an arbitrary rotation position as a relative steering angle, and a rotation position of the steering wheel in a neutral position. When the neutral signal generating means generates a neutral signal, a wheel speed detecting means for detecting each wheel speed of the left and right wheels, respectively, and when the neutral signal generating means generates a neutral signal, the wheel speed detecting means A zero point for determining the relative steering angle detected by the relative steering angle detecting means as a zero point correction value on condition that the difference between the detected wheel speeds is substantially smaller than the rotation angle of the steering wheel at least less than 360 degrees from the neutral state. A vehicle low speed system including a correction value determining means and an absolute steering angle calculating means for calculating the absolute steering angle based on the detected relative steering angle and the determined zero point correction value. Rigidity control device. 3. The absolute steering angle detecting means according to claim 1, wherein the relative steering angle detecting means detects a rotation angle from an arbitrary rotation position of the steering wheel as a relative steering angle, and the rotation position of the steering wheel is a neutral position. When the neutral signal generating means generates a neutral signal, a wheel speed detecting means for detecting each wheel speed of the left and right wheels, respectively, and when the neutral signal generating means generates a neutral signal, the wheel speed detecting means The relative steering angle detected by the relative steering angle detecting means is determined as a zero point correction value on the condition that the difference between the detected wheel speeds indicates the vicinity of the neutral state of the steering wheel, and the neutral signal generating means. When the neutral signal is generated, the relative steering angle detection means detects the difference between the wheel speeds by the relative steering angle detection means on the condition that the steering wheel is in the vicinity of a state in which the steering wheel is rotated 360 degrees from the neutral state. A zero point correction value determining means for determining a value obtained by adding or subtracting 360 degrees to the detected relative steering angle as a zero point correction value, and the absolute steering angle is calculated by the detected relative steering angle and the determined zero point correction value. A roll rigidity control device for a vehicle, which is configured by an absolute steering angle calculation means for 4. The absolute steering angle detecting means according to claim 1, the relative steering angle detecting means for detecting a rotation angle of a steering wheel from an arbitrary rotation position as a relative steering angle, and the wheel speeds of the left and right wheels. Wheel speed detection means for detecting each, absolute steering angle estimation means for estimating an absolute steering angle based on the difference between the detected wheel speeds, relative to each other by the detected relative steering angle and the estimated absolute steering angle A roll of a vehicle comprising zero-point correction value calculation means for calculating a zero-point correction value of a steering angle, and absolute steering angle calculation means for calculating the absolute steering angle based on the detected relative steering angle and the calculated zero-point correction value. Rigidity control device. 5. The absolute steering angle detecting means according to claim 1, the relative steering angle detecting means for detecting a rotation angle of a steering wheel from an arbitrary rotation position as a relative steering angle, and the wheel speeds of the left and right wheels. When the change of the relative steering angle detected by the wheel speed detecting means and the relative steering angle detecting means is small for a predetermined period of time continuously and the difference between the wheel speeds detected by the wheel speed detecting means is small, Zero point correction value determining means for determining the relative steering angle detected by the relative steering angle detecting means as a zero point correction value, and absolute steering for calculating the absolute steering angle based on the detected relative steering angle and the determined zero point correction value. A roll rigidity control device for a vehicle, which is configured by an angle calculation means. 6. A vehicle absolute steering angle detecting device for detecting an absolute steering angle from a neutral state of a steering wheel, wherein a steering signal is generated in response to rotation of the steering wheel in small increments, and the steering wheel travels straight ahead of the vehicle. Steering angle sensor that generates a neutral signal when in a neutral state corresponding to the state, and a relative steering angle that detects a rotation angle from an arbitrary rotation position of the steering wheel as a relative steering angle according to a rotation signal from the steering angle sensor. A detection means; a wheel speed detection means for detecting each wheel speed of the left and right wheels; and a difference between the wheel speeds detected by the wheel speed detection means when the steering angle sensor is generating a neutral signal. The relative steering angle detected by the relative steering angle detecting means is determined as a zero-point correction value on condition that the rotation angle is less than 360 degrees from the neutral state. Absolute steering angle detection for a vehicle, comprising: zero-point correction value determining means; and absolute steering angle calculating means for calculating the absolute steering angle based on the detected relative steering angle and the determined zero-point correction value. apparatus. 7. An absolute steering angle detection device for a vehicle, which detects an absolute steering angle from a neutral state of the steering wheel, wherein the steering signal generates a rotation signal corresponding to each rotation of the steering wheel by a small angle, and the steering wheel advances straight ahead of the vehicle. A steering angle sensor that generates a neutral signal when in a neutral state corresponding to the state and in a position rotated by 360 degrees from the neutral state, and from an arbitrary rotational position of the steering wheel according to the rotation signal from the steering angle sensor. Relative steering angle detecting means for detecting the rotation angle of the wheel as a relative steering angle, wheel speed detecting means for detecting each wheel speed of the left and right wheels, and the wheel speed detecting means when the steering angle sensor generates a neutral signal. The relative steering angle detected by the relative steering angle detecting means is set to zero on the condition that the difference between the wheel speeds detected by the means indicates the vicinity of the neutral state of the steering wheel. The relative steering is determined as a correction value, and when the steering angle sensor is generating a neutral signal, the difference between the wheel speeds indicates the vicinity of a state where the steering wheel is rotated 360 degrees from the neutral state. A zero point correction value determining means for determining a value obtained by adding or subtracting 360 degrees to the relative steering angle detected by the angle detecting means as a zero point correction value; and the absolute value based on the detected relative steering angle and the determined zero point correction value. An absolute steering angle detection device for a vehicle, comprising: absolute steering angle calculation means for calculating a steering angle.