JP3209030B2 - Vehicle suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vehicle shock absorber.
The present invention relates to a suspension control device capable of changing a damping coefficient of a suspension.

[0002]

2. Description of the Related Art Conventionally, in a vehicle equipped with a shock absorber whose damping coefficient can be adjusted, an actuator is driven by a command from a controller to improve the grounding property and riding comfort of the wheel, and the damping coefficient of the shock absorber is adjusted. Variable control is known, for example, there is an apparatus disclosed in Japanese Patent Application Laid-Open No. 6-92126.

[0003] In this method, the speed in the roll or pitch direction of a vehicle body is detected, and the magnitude of a damping coefficient of a shock absorber for damping the vehicle body is corrected in accordance with the detected speed. It is intended to suppress roll or pitch movement of the vehicle body with similar vibration damping characteristics.

[0004]

By the way, considering skyhook damper control in a case where the roll and pitch vibration inputs are simultaneously applied to the vehicle body, for example, as shown in FIGS. While the right front wheel 2FR rides on the protrusion while the other wheels, the left front wheel 2FL and the left and right rear wheels 2RL, 2RL are traveling on a flat road, the vehicle body rolls counterclockwise as shown in FIG. When the movement occurs, a pitch movement in the squat direction occurs as shown in FIG.

[0005] Now, the left and right front wheels 2FL, considering the roll direction of the attenuation coefficient of focusing on 2FR by skyhook damper control, the ideal left and right front wheels of the damping force by the skyhook damper control each F _FR, and F _FL Then, it is expressed as follows. FR indicates the right front wheel and FL indicates the left front wheel (the same applies hereinafter).

F _FR = −Cs × ZV _FR (a1) F _FL = −Cs × ZV _FL (a2) where Cs; ideal damping coefficients ZV _FR and ZV _FL by the skyhook damper control. Corresponding Absolute Absolute Speed The ideal damping force F _FR -F _FL in the body roll direction by the skyhook damper control is as follows.

F _FR −F _FL = −Cs × (ZV _FR −ZV _FL ) (a3) Target damping coefficients C _FR , C of the left and right front wheel shock absorbers
_FL is obtained by the following equations.

C _FR = −Cs × ZV _FR / HV _FR (a4) C _FL = −Cs × ZV _FL / HV _FL (a5) Note that the relative speeds HV _FR and HV _FL are the absolute speeds on the spring, X
_FR ', X _FL', the absolute velocity of the X _0FR unsprung ', X _0FL' in which tries to be computed as follows.

HV _FR = X _0FR '−X _FR ' HV _FL = X _0FL '−X _FL ' The target damping coefficient C _FR of the right front wheel obtained by the above equation (a4) is determined by the absolute speed on the spring in the positive direction ( 14, the relative speed HV _FR also becomes a negative value because it also becomes a positive direction.
Since the damping coefficient of the shock absorber can only be set to a positive value, the target damping coefficient C _FR of the left front wheel is set to the minimum damping coefficient C _min that can be set by the shock absorber, so that ideal skyhook damper control is performed. Is not done.

On the other hand, the target damping coefficient C _FL of the left front wheel obtained by the above equation (a5) is determined by the direction in which the absolute speed on the spring is negative (FIG. 14).
(Downward), the relative speed HV _FL is in the positive direction, and therefore has a positive value, so that ideal skyhook damper control can be performed.

If the damping force of each wheel actually generated is F _FR ′ and F _FL ′ when the damping coefficients of the left and right front wheels are set as described above, F _FR ′ = C _FR × HV _FR = C _min × HV _FR (a6) F _FL ′ = C _FL × HV _FL = −Cs × ZV _FL = F _FL (a7), and the damping force F _FL ′ generated in the left front wheel 2FL is calculated by the above (a2 ) is consistent with the ideal damping force F _FR caused by skyhook damper control determined by the formula, the damping force F _FR generated in the right front wheel 2FR, which rides on the projection 'is ideal skyhook above (a1) formula Ideal damping force F _FL by damper control
, The roll-direction damping force F _FR '-F _FL ' actually generated is expressed by the following equation.

F _FR '−F _FL ' = C _min × HV _FR −F _FL = F _FR − (− Cs × ZV _FL ) + C _min × HV _FR −F _FL = F _FR −F _FL + ΔC _min − ( −Cs × ZV _FR / HV _FR )｝ × HV _FR > F _FR −F _FL (a8) That is, the roll actually generated with respect to the roll damping force F _FR −F _FL by the ideal skyhook damper control. Since the damping force F _FR '−F _FL ' is insufficient, the movement of the vehicle body in the roll direction is not suppressed.

At the same time, as shown in FIG. 15, in the pitch direction of the vehicle body, the sprung acceleration ZG _FR of the right front wheel 2FR is set to the forward direction, and the right and left rear wheels 2R
The sprung accelerations ZG _RR , ZG _RL of R, 2RL are both in the negative direction, causing pitch movement in the squat direction (clockwise in the figure), and in the same manner as in the roll direction, the right front wheel 2FR
Is set to the minimum damping coefficient _Cmin , so that the damping force in the pitch direction is insufficient.

A diagonal roll motion obtained by combining the roll motion and the pitch direction motion occurs in a direction of displacing the vehicle body of the right front wheel 2FR upward about a diagonal line connecting the left front wheel 2FL and the right rear wheel 2RR. I do.

However, in the above conventional suspension control device, the target damping coefficient for suppressing the roll and pitch movement of the vehicle body calculated by the controller by the skyhook damper control is the minimum damping that can be set by the shock absorber. When the coefficient is smaller than the coefficient, the damping force in the diagonal roll direction in which the roll motion and the pitch motion are combined is the ideal sky force because the minimum damping coefficient that can be set by the shock absorber is merely used as described above. In some cases, the damping force by the hook damper control is insufficient, and the diagonal roll motion generated in the vehicle body cannot be reliably suppressed.

Accordingly, the present invention has been made in view of the above-mentioned problems, and the present invention has been made to reduce the diagonal roll motion of the vehicle body even when the target damping coefficient by the skyhook damper control becomes smaller than the minimum damping coefficient that can be set by the shock absorber. It is an object of the present invention to provide a vehicle suspension control device that can be reliably suppressed.

[0017]

As shown in FIG. 16, the first invention comprises damping coefficient changing means 51 interposed between the sprung and unsprung portions of each wheel to change the damping coefficient. Shock absorber 3, and sprung absolute speed detecting means 52 for detecting the absolute speed of the vehicle in the vertical direction on the spring of each wheel;
A relative speed detecting means 53 for detecting a relative speed in the vehicle body vertical direction with respect to an unsprung spring of each wheel, and the shock absorber 3 based on the detected values of the sprung absolute speed detecting means 52 and the relative speed detecting means 53. A control means for calculating a target damping coefficient and driving the damping coefficient changing means so that the damping coefficient of the shock absorber 3 coincides with the target damping coefficient. Comparing means 55 for comparing a target damping coefficient of a diagonal wheel with a minimum damping coefficient C _min that can be set by the shock absorber; and based on the comparison result, at least one target damping coefficient that can be set by the shock absorber. and sets the minimum damping coefficient C _min as the target damping coefficient in the case of less than the damping coefficient C _min, diagonal Comprising the other and diagonal roll damping correction means 56 the target damping coefficient of the shock absorber is increased from the target damping coefficient of the wheel.

The second invention, as shown in FIG. 16, is a shock absorber 3 provided with damping coefficient changing means 51 interposed between the sprung and unsprung portions of each wheel to change the damping coefficient. A sprung absolute speed detecting means 52 for detecting an absolute speed of the vehicle in the vertical direction on a spring of each wheel; a relative speed detecting means 53 for detecting a relative speed of the vehicle in a vertical direction with respect to the unsprung spring of each wheel. The target damping coefficient of the shock absorber 3 is calculated based on the detection values of the sprung absolute speed detecting means 52 and the relative speed detecting means 53, and the damping coefficient of the shock absorber 3 matches the target damping coefficient. In a vehicle suspension control apparatus having a control means for driving a damping coefficient changing means, the control means includes a target damping coefficient and a shock absorber. A comparing means 55 for comparing the constant minimum acceptable attenuation coefficient C _min, when the target damping coefficient of the wheels on the diagonal on the basis of the comparison result of said minimum damping coefficient C _min smaller than the minimum damping coefficient C _The target attenuation coefficient with the larger difference between _min and the target attenuation coefficient is the minimum attenuation coefficient C
While set to _min, and a diagonal on the other shock absorber of the diagonal roll damping correction means causes the target damping coefficient is increased from the minimum damping coefficient C _min 56.

According to a third aspect of the present invention, as shown in FIG. 16, in the first or second aspect, the diagonal roll attenuation correction means 56 includes a target attenuation coefficient of the shock absorber 3 on the diagonal. Diagonal roll damping force calculating means 5 for calculating the shortage of the diagonal roll damping force of the vehicle body based on
7, the correction coefficient calculating means 58 for calculating a diagonal roll damping correction factor C ₂ in accordance with the shortage of the diagonal roll damping force
When the diagonal roll damping correction factor C ₂ to increase the target damping coefficient is added to the target damping coefficient adding means 59
And

In a fourth aspect based on the third aspect, the correction coefficient calculating means compares a difference between a target attenuation coefficient and an attenuation coefficient of the minimum attenuation coefficient C _{min in} a diagonal direction. computing the diagonal roll damping correction factor C ₂ corresponding to the difference between the attenuation coefficient of the diagonal.

[0021]

Therefore, the first invention compares the target damping coefficient of the shock absorber of the diagonal wheel with the minimum damping coefficient C _min that can be set by the shock absorber, and determines that at least one of the target damping coefficients is smaller than the shock absorber. If the minimum damping coefficient _{Cmin is} smaller than the minimum damping coefficient _Cmin , the minimum damping coefficient _Cmin is set as a target damping coefficient, and the damping coefficient of the shock absorber of the other wheel on the diagonal is increased from the target damping coefficient. Thus, the shortage of the damping force in the diagonal roll direction can be compensated for to suppress the diagonal roll motion in which the roll and the pitch motion of the vehicle body are combined.

Further, the second invention, pairs compares the target damping coefficient of the shock absorber of the wheel on the corner diagonal on the target damping coefficient of the minimum attenuation coefficient less than C _min settable by the shock absorber both in In this case, the smaller one of the difference between the minimum damping coefficient _Cmin and the target damping coefficient is set as the minimum damping coefficient _Cmin, and the other diagonal damping coefficient is made larger than the minimum damping coefficient _Cmin . This makes it possible to compensate for the shortage of the damping force in the diagonal roll direction and suppress the diagonal roll motion in which the roll and the pitch motion of the vehicle body are combined.

According to a third aspect of the present invention, the diagonal roll damping correction means calculates a shortage of the damping force of the vehicle body in the diagonal roll direction based on a difference between the target damping coefficients of the shock absorbers on the diagonal. diagonal roll damping correction factor C ₂ calculated in accordance with the shortage of the diagonal roll damping force is added to the target damping coefficient of the other shock absorber on the minimum damping coefficient C _min shock absorber paired set to corner This makes it possible to compensate for the insufficient damping force in the diagonal roll direction and suppress the diagonal roll motion in which the roll and pitch motions of the vehicle body are combined.

According to a fourth aspect of the present invention, the correction coefficient calculating means calculates a difference between a target damping coefficient and the minimum damping coefficient C _min for each diagonal, and further calculates a difference between these diagonal damping coefficients. Roll attenuation correction coefficient C ₂ calculated by
Is added to the target damping coefficient, so that diagonal roll motion in which roll and pitch motion of the vehicle body are combined can be suppressed.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, each wheel 2FL-
Shock absorber 3FR ~ between 2RL and body 1
The 3RL and the spring 4 are interposed, respectively, and the vehicle body 1 constitutes a sprung part, and the wheels 2FR to 2RL constitute an unsprung part. Note that F
R indicates a front right wheel, FL indicates a front left wheel, RR indicates a rear right wheel, RL indicates a rear left wheel, and so on.

This shock absorber 3FR to 3RL
Includes a damping force adjusting mechanism driven by actuators 7FR to 7RL as a means for changing the damping coefficient, as will be described later, and an actuator 7FR driven in accordance with a command from a controller 10 mainly constituted by the microcomputer 100. Each of the shock absorbers 3FR to 3RL is set to a target damping coefficient by .about.7RL.

The controller 10 includes acceleration sensors 6FR to 6R for detecting vertical acceleration of the vehicle body 1, that is, acceleration on a spring, and a vehicle height sensor 5FR for detecting a relative displacement between the vehicle body 1 and each of the wheels 2FR to 2RL. ５5RL, the target values of the damping coefficients of the shock absorbers 3FR〜RL are calculated based on the skyhook damper control, and the actuators 7FR〜7RL are calculated.
Is output as a control signal to change the damping coefficients of the shock absorbers 3FR to 3RL.

As shown in FIG. 2, the vehicle height sensors 5FR to 5FR
The signals from the RL and the acceleration sensors 6FR to 6R are converted into digital signals via the input interface circuit 111 and the A / D converter 112 and then input to the microcomputer 100. As will be described later, the microcomputer 100 calculates an ideal damping coefficient of each of the shock absorbers 3FR to RL based on the skyhook damper control, and outputs a target damping coefficient calculated based on the ideal damping coefficient to a D / A converter. 113, driver circuit 11
After converting and amplifying to an analog signal through the actuator 4, actuators 7FR to 7FR of the shock absorbers 3FR to 3RL
Output to RL as a control signal.

Hereinafter, the means for detecting each signal input to the controller 10 will be described in detail, and then the damping force adjusting mechanism of the shock absorbers 3FR to 3RL and the control operation will be described in this order.

[Acceleration Sensor] The acceleration sensors 6FR to 6R for detecting the acceleration in the vertical direction of the vehicle body on the spring are shown in FIG.
As shown in FIG. 4, the base end is fixed to the vehicle body 1 and a mass 61 is provided at a free end of a semiconductor piezo element 60 arranged substantially horizontally, and the magnitude of the acceleration applied to the mass 61 Since the semiconductor piezo element 60 is distorted according to the above, the magnitude of the acceleration applied to the vehicle body 1 in the vertical direction is converted into a voltage.

As shown in FIG. 4, the semiconductor piezo element 60
Outputs 2.5 V at 0 G, and in FIG. 3, outputs 4.0 V at an upward acceleration of 1 G in the figure and 1.0 V at a downward acceleration of −1 G in FIG.

Here, as shown in FIG. 5, the acceleration sensors 6FR to 6R are provided at three predetermined positions on the vehicle body 1, and the acceleration sensors 6FR are provided near the right front wheel 2FR. Near the acceleration sensor 6FL, the right rear wheel RR
It is disposed an acceleration sensor 6R is in the vicinity of, and the acceleration sensor 6FR, 6FL is provided substantially parallel to the front axle, to the detection to acceleration of the acceleration sensor 6FR~6R and ZG _1, ZG _2, ZG ₃ respectively .

The acceleration on the sprungs is determined for each of the wheels 2FR to 2RL.
It is necessary to obtain the three acceleration sensors 6
Since the arrangement positions of FR to 6R are known, the controller 10 calculates the acceleration ZG _FR generated on the springs of the wheels 2FR to 2RL from the _three accelerations ZG _{1 to} ZG 3 generated on the vehicle body 1 by the following equation. ＺZG _RL is calculated.

ZG _FR = (a ₁ × ZG ₁ + b ₁ × ZG ₂ + c ₁ × ZG ₃ ) / d (1) ZG _FL = (a ₂ × ZG ₁ + b ₂ × ZG ₂ + c ₂ × ZG ₃ ) / d (2) ZG _RR = (a ₃ × ZG ₁ + b ₃ × ZG ₂ + c ₃ × ZG ₃ ) / d (3) ZG _RL = (a ₄ × ZG ₁ + b ₄ × ZG ₂ + c ₄ × ZG ₃ ) / d ... (4) _{However, a 1 = -L 2 L 4} - (L 1 + L 3) L 6 -L 1 L 2 b 1 = L 2 L 4 + L 3 L 6 c 1 = L 1 L 6 a _{2 = L 2 L 5 - (} L 1 + L 3) L 6 -L 1 L 2 b 2 = -L 2 L 5 + L 3 L 6 c 2 = L 1 L 6 a 3 = -L 2 L 4 - (L _{1 + L 3) L 7 -L} 1 L 2 b 3 = L 2 L 4 -L 3 L 7 c 3 = -L 1 L 7 a 4 = L 2 L 5 - (L 1 + L 3) L 7 -L 1 _{L 2 b 4 = -L 2 L} 5 -L 3 L 7 c 4 = -L 1 L 7 d = -L 1 L 2 L 1; acceleration sensor 6FR and 6FL The width direction of the distance L _2; acceleration sensor 6FR and distance full length body direction 6R L _3; acceleration sensor 6FR and the distance in the vehicle width direction of the 6R L _4; right front and rear wheels 2FR, from the axis passing through 2RR to acceleration sensors 6FR In the vehicle width direction L ₅ ; Distance in the vehicle width direction from the axis passing through the left front and rear wheels 2FL, 2RL to the acceleration sensor 6FR L ₆ ; Distance in the vehicle full length direction from the front axle to the acceleration sensor 6FR L ₇ ; Distance in the vehicle full length direction from the axle to the acceleration sensor 6FR According to the above equations (1) to (4), three accelerations ZG ₁ ,
ZG _2, ZG ₃ and the acceleration from the arrangement position of the sensor 6FR~6R sprung corresponding to each wheel 2FR~RL acceleration Z
G _FR , ZG _FL , ZG _RR , and ZG _RL can be obtained.

[Vehicle Height Sensors] The vehicle height sensors 5FR to 5RL for detecting the relative displacement between sprung and unsprung, that is, the relative displacement between the vehicle body 1 and the wheels 2FR to 2RL, are provided for each of the wheels 2FR to 5FR.
2RL, and signals from these sensors are sent to a controller 1 mainly composed of a microcomputer.
Input to 0.

Each of the vehicle height sensors 5FR to 5RL is composed of, for example, a potentiometer, and the base of the connecting rod 22B is connected to the shaft of the vehicle height sensors 5FR to 5RL as shown in FIG. The middle end of an arm 21 that swings freely and the free end of a connecting rod 22B are connected via a connecting rod 22A, and the relative displacement of the vehicle body 1 in the vertical direction between the wheels 2FR to 2RL and the vehicle body 1 is adjusted as shown in FIG. Is captured as a voltage change corresponding to a change in the angle.

[Damping Force Adjusting Mechanism] FIGS. 8 to 11 show the damping force adjusting mechanisms of the shock absorbers 3FR to 3RL.
The actuators 7FR to 7RL provided on the vehicle body 1 side of the shock absorbers 3FR to 3RL have damping coefficients changed by rotating the control rod 30 as described below.
The RL includes, for example, a step motor.

The pistons 32 constituting the shock absorbers 3FR to 3RL are housed in the inner periphery of a cylinder 31 connected to the wheel side. The inner periphery of the piston 32 has a cylindrical stud 33 A cylindrical spool 34 is coaxially accommodated in the periphery, and the spool 34 is connected to the control rod 30 to be connected to the actuators 7FR to 7FR.
The stud 33 is supported rotatably by the RL.
Is integrally fixed to the inner periphery of the piston 32, and the spool 34 connected to the control rod 30 is rotatable relative to the piston 32 and the stud 33.

The piston 32 and the stud 33 are moved to the compression side stroke of the shock absorber (the contraction direction of the spring 4).
Pressure oil passages 35 and 36 through which hydraulic oil passes, and extension oil passages 37 and 38 through which hydraulic oil passes when the shock absorber extends (stretching direction of the spring 4), are formed. Pressure side valve 35 for generating damping force
A, 35B and extension side valves 37A, 37B are provided. Further, the stud 33 has a through hole 33A communicating the upper surface of the piston 32 and the inner circumference of the stud 33,
2, a through hole 33B communicating the lower surface of the stud 33 with the inner periphery of the stud 33;
A through-hole 33 </ b> C communicating the extension-side oil passage 38 and the inner periphery of the stud 33 is formed.

Here, the spool 34 has a circular oil passage 34A and an elliptical oil passage 34B formed as recesses at predetermined positions on the outer periphery, and the circular oil passage 34A is disposed so as to face the pressure side oil passage 36. At the same time, it communicates with the inner circumference 34C of the spool 34 and the oil chamber 31A via the through hole 34D. On the other hand, the elliptical oil passage 34B is disposed at a position that can face the through holes 33A to 33C of the stud 33, and these through holes 33A to 33C
Are configured to be able to communicate with each other.

Here, the shock absorbers 3FR to 3R
As shown in FIGS. 10A and 10B, the attenuation coefficient of L
Actuator 7FR via control rod 30
In the case of the pressure side oil passage 36, when the spool 34 is rotated in the arrow direction in the figure as shown in FIG. 10B, the circular oil passage is determined. When the pressure side oil passage 36 and the circular oil passage 34A overlap with each other, the area of the communication portion 300 communicating with the pressure side oil passage 36 and the circular oil passage 34A is enlarged, and the damping coefficient is changed to a smaller one. The damping coefficient can be changed to an arbitrary value in accordance with the change in the area of the communication section 300. The setting of the damping coefficient can be changed almost steplessly with high responsiveness. However, the same applies to the elliptical oil passage 34B.

Such shock absorbers 3FR to 3FR
As shown in FIGS. 11A to 11C, the damping coefficient of the RL can be set for each of the compression side and the extension side, that is, the flow path of the hydraulic oil is changed according to the direction of movement of the shock absorbers 3FR to 3RL. Switching is performed as follows, and the attenuation coefficient is also set.

When the damping coefficient on the extension side is large (hard);
As shown in FIG. 11A, the rotation of the spool 34 displaces the elliptical oil passage 34B to a position where it does not face the through holes 33A to 33C of the stud 33, and the hydraulic oil flowing from the oil chamber 31B to the oil chamber 31A A large damping force is generated by a small flow path cross-sectional area by sequentially passing through the inflow portion 37C, the extension side oil passage 37, and the extension side valve 37A between the pressure side valve 35A and the compression side valve 35A.

When the extension-side damping coefficient is small (soft);
As shown in FIG. 11B, the elliptical oil passage 34B is
The hydraulic fluid flowing from the oil chamber 31B to the 31A is rotated by rotating the spool 34 to a position facing the through holes 33A to 33C.
In addition to the case where the above-described damping coefficient is large, by sequentially passing through the inflow portion 37C on the upper surface of the piston 32, the through hole 33A, the elliptical oil passage 34B, the extension oil passage 38, and the extension valve 37B,
A small damping force is generated by increasing the cross-sectional area of the flow path.

The expansion-side damping coefficient is determined in addition to the oil passage 37 and the oil passage 3
8 is selectively communicated, and the overlapping area between the through holes 33A to 33C and the elliptical oil passage 34B is determined by the actuator 7F.
By adjusting R to RL, an arbitrary attenuation coefficient can be set.

When the compression coefficient on the compression side is large (hard); as shown in FIG.
The hydraulic oil flowing from the oil chamber 31A to the oil chamber 31A is turned into a small flow path cross-sectional area by sequentially passing through the pressure side oil path 35 and the pressure side valve 35A of the piston 32. As a result, a large damping force is generated.

When the damping coefficient on the pressure side is small (soft); the spool 34 is rotated to a position where the circular oil passage 34A faces the oil passage 35 of the stud 33 as shown in FIG. The hydraulic oil flowing into the spool 31B has an inner circumference 34C of the spool 34,
4D, circular oil path 34A, pressure side oil path 36, pressure side valve 35
By sequentially passing through B, the cross-sectional area of the flow path is increased, and a small damping force is generated.

The damping coefficient on the compression side is not only
6 and the oil passage 36 and the circular oil passage 34
By adjusting the overlapping area of A with the actuators 7FR to 7RL, an arbitrary damping coefficient can be set.

[Control Operation] The controller 10 calculates a target damping coefficient from an ideal damping coefficient based on the skyhook damper control based on the vertical acceleration and relative displacement of the vehicle body 1 detected by the sensors, A control signal is output to the actuators 7FR to 7RL in accordance with the target damping coefficient, and the damping coefficients of the shock absorbers 3FR to 3RL are changed to target values.

FIGS. 13 and 14 are flowcharts showing an example of the control performed by the controller 10, which is executed at predetermined time intervals by a timer interrupt or the like, and will be described in detail below with reference to these flowcharts.

First, in step S1, the acceleration sensor 6FR
The vertical acceleration ZG _{1 of} the vehicle body 1 detected by 6RL
The ZG _3, in step S2, the vehicle height sensor 5FR~5FR
Detected relative displacement H _FR between the vehicle body 1 and the wheels 2FR to 2RL
Read ~H _RL.

Next, in step S3, the above-described step S1
Than acceleration ZG ₁ ~ZG ₃ read in the above (1) to
The accelerations ZG _FR to ZG _RL generated on the springs of the wheels 2FR to 2RL are calculated based on the equation (4), and in step S4, these accelerations ZG _{FR to} ZG _RL are integrated to obtain the absolute velocity ZV on the springs. Each of _{FR to} ZV _RL is calculated.

On the other hand, in step S5, step S5
By differentiating the relative displacements H _{FR to} H _RL read in step 2, the relative speeds HV _{FR to} HV _RL of the sprung and unsprung parts are calculated.

The thus obtained sprung absolute velocity ZV _FR ~
And ZV _RL, based on the relative velocity HV _FR ~HV _RL on the unsprung spring, the ideal damping coefficient C which is a target value of an ideal damping coefficient by the skyhook damper control step S6
It is calculated by the following formula _{SFR ~C SRL.}

C _Si = −Cs × ZV _i / HV _i (5) where Cs is a coefficient of skyhook damper control, and i = F
R, FL, RR, and RL are shown (the same applies hereinafter).

Next, in step S7, the magnitudes of these ideal damping coefficients C _Si are compared with the maximum damping coefficient C _max and the minimum damping coefficient C _min that can be set by the shock absorbers 3FR to 3RL. the Fukkudanpa control damping coefficients C _1FR -C _1RL set as in the following (6) to (8).

When C _Si ≦ C _min C _1i = C _min (6) When C _min <C _Si <C _max C _1i = C _Si (7) When C _Si > C _max C _1i = C _max (8) Step S8 is the ideal damping coefficient C _Si and relative speed H of the skyhook damper control obtained in steps S5 and S6.
A subroutine for performing an operation of diagonal rolling direction of the damping correction factor C _2i of each wheel 2FR~2RL than V _i, 13
After performing the arithmetic processing based on the flowchart shown in
It returns to step S9.

In the calculation of the diagonal roll attenuation correction coefficient C _2i , first, in step S101, the ideal attenuation coefficient C _Sj of the skyhook damper control obtained in step S6 (provided that j = RL, RR, FL, FR) , A diagonal wheel of the wheel of interest. The same applies to the other diagonal wheels), and a comparison is made as to whether the other diagonal is smaller than a minimum damping coefficient C _min that can be set by the shock absorber 3j. That is, when attention is paid to the left front wheel 2FL, it is compared whether the ideal damping coefficient C _SRL of the right rear wheel 2RR is less than C _min .

If it is determined in step S101 that the ideal damping coefficient C _Sj of the diagonal wheel is equal to or more than the minimum damping coefficient C _min , it is not necessary to correct the damping force in the diagonal roll direction. The angular roll attenuation correction coefficient C _2i is set to 0, and the sub-running is terminated.

On the other hand, if the ideal damping coefficient C _Sj of the diagonal wheel is less than the minimum damping coefficient C _min , the insufficient damping force F _Uj of the diagonal wheel 2j is calculated by the following equation in step S102. .

F _Uj = (C _min −C _Sj ) × HV _j (9) Next, in step S103, the ideal damping coefficient C _Si by the skyhook damper control of the wheel 2i of _interest exceeds the minimum damping coefficient C _min . Is determined, and if it exceeds the minimum attenuation coefficient C _min , the process proceeds to step S104, where a diagonal roll attenuation correction coefficient C _2i is calculated by the following equation.

C _2i = F _Uj / HV _i (10) On the other hand, if the ideal damping coefficient C _Si is equal to or _smaller than the minimum damping coefficient C _{min in} the judgment of step S103, step S10
Proceeding to 5, the insufficient damping force F _Ui of the wheel 2i of _interest is calculated by the following equation.

F _Ui = (C _min −C _Si ) HV _i (11) Here, in step S106, the shortage of the other wheel on the diagonal to the insufficient damping force F _Ui of the wheel of interest obtained in step S105. A comparison is made with the damping force F _Uj, and if the insufficient damping force F _Uj of the diagonal wheel is larger, the process proceeds to step S107 to calculate the diagonal roll damping correction coefficient C _2i ,
If the insufficient damping force F _Ui of the wheel of interest is greater, it is not necessary to correct the damping force in the diagonal roll direction, so the diagonal roll damping correction coefficient C _2i = 0 is set in step S108.

In step S107, the diagonal roll damping correction coefficient C is _{calculated from} these insufficient damping forces F _Ui and F _Uj and the relative sprung and unsprung speed HV _{i of} the wheel of _interest based on the following equation.
Perform _2i operation.

C _2i = (F _Uj −F _Ui ) / HV _i (12) After _{calculating the} diagonal roll attenuation correction coefficient C _2i in this way, the process returns to step S11 in FIG.

In step S9, the skyhook damper control damping coefficient C _1i obtained in step S7 and the diagonal roll damping correction coefficient C _2i obtained in steps S104 and S107.
From the following equation, each shock absorber 3i of each wheel 2i
Calculating a target damping coefficient C _i to be set to.

[0068] of _{C i = C 1i + C 2i} ... (13) Next, at step S12, the target damping coefficient C _i obtained in the current processing target damping coefficient C _i obtained in the previous processing (n-1) The differences ΔC _i are calculated, and in step S13, the actuators 7FR to 7RL corresponding to the differences ΔC _i are calculated.
Rotation angle .delta.C _i by calculating the respective wheels 2FR~2R a command signal corresponding to the step S14 the rotational angle .delta.C _i
Output to L actuators 7FR to 7RL.

By repeating steps S1 to S12 at predetermined time intervals, the diagonal roll motion applied to the vehicle can be suppressed as follows.

A vehicle traveling on a flat road surface is shown in FIG.
4. As shown in FIG. 15, when the right front wheel 2FR rides on a protrusion or a step, while the other wheels are on a flat road, an input from the protrusion causes the right front wheel 2FR to spring forward (upward in the figure). Acceleration VG _FR is generated, while accelerations VG _FL , VG in the negative direction (downward in the figure) appear on the springs of the other wheels.
_RR and VG _RL occur, and the roll movement counterclockwise in the figure and the pitch mobility in the squat direction in the figure are combined to produce the left front wheel 2F.
Right front wheel 2FR around a diagonal line connecting L and right rear wheel 2RR
A diagonal roll motion that displaces the vehicle body upward occurs.
In the drawing, X _i and X _0i indicate the sprung and unsprung absolute displacements, respectively.

Here, the theoretical target values of the damping force of each wheel by the skyhook damper control are represented by F _FR , F _FL , F _RR , F
_Assuming that _RL , the following equation is obtained.

F _FR = −Gs × ZV _FR (14) F _FL = −Gs × ZV _FL (15) F _RR = −Gs × ZV _RR (16) F _RL = −Gs × ZV _RL (17) The theoretical target value of the roll damping force of the vehicle body 1 is expressed by the following equation.

F _FR −F _FL + F _RR −F _RL = −Cs × (VZ _FR −VZ _FL + VZ _RR −VZ _RL ) (18) Similarly, the theoretical target value of the pitch damping force of the vehicle body 1 is It is expressed by the following equation.

F _FR + F _FL −F _RR −F _RL = −Cs × (VZ _FR + VZ _FL −VZ _RR + VZ _RL ) (19) At this time, the skyhook damper control damping coefficient C _1i is obtained by the above (5), From the expressions (6) to (8), the following expression is obtained.

C _1FR = C _min C _1FL = C _SFL C _1RR = C _SRR C _1RL = C _{SRR In} other words, the ideal damping coefficient C _SFR by the skyhook damper control of the right front wheel 2FR is negative, but actually, it is a shock absorber. minimizing the damping coefficient C _FR of 3FR damping coefficient C _min
Therefore, the damping coefficient C _FR is set to the minimum damping coefficient C _min .

On the other hand, for the other wheels, the ideal damping coefficient C
_{Since Si} is positive, the target damping coefficient C _i of each shock absorber 3i can be set to the ideal damping coefficient C _Si . In this way, when the target damping coefficient C _i of each wheel is set, the damping force actually generated by each wheel is represented by F _FR ′, F _FL ′, and F _FR ′.
_{Assuming that RR} ′ and F _RL ′, the following equation is obtained.

[0077] _{F FR '= C FR × HV} FR = C min × HV FR = -Gs × ZV FR + C min × HV FR + Cs × VZ FR ... (20) F FL' = C FL × HV FL = -Cs × VZ _FL (21) F _RR ′ = C _RR × HV _RR = −Cs × VZ _RR (22) F _RL ′ = C _RL × HV _RL = −Cs × VZ _RL (23) Here, the above (18) When the roll damping force and the pitch damping force are obtained in the same manner as in the equations (19), (24) and (2)
Equation 5) is obtained.

[0078] _{F FR '-F FL' + F} RR '-F RL' = -Cs × (VZ FR -VZ FL + VZ RR -VZ RL) + C min × HV FR + Cs × VZ FR ... (24) F FR '+ F _{FL '-F RR' -F RL '} = -Cs × (VZ FR + VZ FL -VZ RR + VZ RL) + C min × HV FR + Cs × VZ FR ... (25) thereof (24), (25) the actual When the generated roll and pitch damping force are compared with the theoretical values based on the skyhook damper control of the above equations (18) and (19), (24)
The second and subsequent items in the equation (25) are insufficient for the damping force, so that the roll and pitch are not suppressed, and therefore the diagonal roll is not suppressed.

However, the diagonal roll motion generated in the vehicle body 1 by correcting the target damping coefficient C _i by the diagonal roll damping correction coefficient C _2i obtained in steps S104 and S107 is suppressed as follows. It is.

First, from steps S104 and S107, the diagonal roll attenuation correction coefficient C _2i is as follows.

C _2FR = 0 C _2FL = 0 C _2RR = 0 C _2RL = (C _min × HV _FR + Cs × VZ _FR ) / HV _RL That is, the ideal damping coefficient C _SFR of the right front wheel 2FR is the minimum damping of the shock absorber 3i. Since it is smaller than the coefficient C _min, only the diagonal roll attenuation correction coefficient C _2RL of the left rear wheel 2RL on the diagonal of the right front wheel 2FR has a positive value, while the other diagonal roll attenuation correction coefficients C _2i are It becomes 0. Therefore,
From the above step S9, the target damping coefficient C _i of each wheel is as follows.

C _FR = C _min C _FL = −Cs × VZ _FL / HV _FL C _RR = −Cs × VZ _RR / HV _RR C _RL = −Cs × VZ _RR / HV _RR + (C _min × HV _FR + C
s × VZ _FR ) / HV _RL Therefore, the target damping coefficient C _FR of the right front wheel 2FR is set to the minimum damping coefficient C _min , while the target damping coefficient C _RL of the left rear wheel 2RL on the diagonal of the right front wheel is rolled. The second and subsequent items are added corresponding to the shortage of the damping force and the pitch damping force, and the other wheels are equivalent to the ideal damping coefficient C _Si by the skyhook damper control.

_Assuming that the corrected damping force generated on each wheel by the target damping coefficient C _i corrected by the diagonal roll damping correction coefficient C _2i is F _FR ", F _FL ", F _RR ", F _RL ". ,
It becomes like the following formula.

[0084] _{F FR "= C FR × HV} FR = C min × HV FR = -Gs × ZV FR + C min × HV FR + Cs × VZ FR ... (20 ') F FL" = C FL × HV FL = -Cs × VZ _FL ... (21 ′) F _RR “= C _RR × HV _RR = −Cs × VZ _RR ... (22 ′) F _RL ” = C _RL × HV _RL = −Cs × VZ _RL + C _min × HV _FR + Cs × VZ _FR (23 ') Therefore, the equations (20) to (23) before correction by the diagonal roll attenuation correction coefficient _C2i and the equations (20') to (2) after correction
Comparing the expressions (3 '), since the shortage of the roll and the pitch damping force is added in the second and subsequent items of the expression (23'), the roll damping force by these corrected damping forces F _FR "to F _RL " is added. And the pitch damping force are: F _FR “−F _FL ” + F _RR “−F _R ” _L = −Cs × (VZ _FR −VZ _FL + VZ _RR −VZ _RL ) (18 ′) F _FR “+ F _FL “ −F _RR “−F _RL ” = −Cs × (VZ _FR + VZ _FL −VZ _RR + VZ _RL ) (19 ′), which is equal to the theoretical value obtained by the skyhook damper control of the above equations (18) and (19). Thus, the diagonal roll motion in which the roll mobility and the pitch motion of the vehicle body are combined can be reliably suppressed, and the stability of the vehicle can be improved.

Also, when the right front wheel 2FR rides on a large projection and the left rear wheel 2RL rides on a small projection, a diagonal roll motion occurs in the same manner as described above.
When both the FR and the ideal damping coefficient C _Si of the left rear wheel 2RL are the minimum damping coefficient C _min , the target damping coefficient C _i having the larger difference between the ideal damping coefficient C _Si and the minimum damping coefficient C _min is set to the minimum damping coefficient. while setting the coefficient C _min, the other target damping coefficient C _i on the diagonal, as shown in step S102,105～108, versus diagonal roll damping obtained in accordance with the angular roll damping force shortfall By increasing by adding the correction coefficient C _2i , the insufficient diagonal roll damping force can be compensated for by the other wheel on the diagonal in the same manner as described above, and the diagonal roll motion generated in the vehicle body can be suppressed. As a result, the stability of the vehicle can be improved.

[0086]

As described above, the first aspect of the present invention compares at least one of the target damping coefficients C _min of the shock absorbers of the wheels on the diagonal with the minimum damping coefficient C _min that can be set by the shock absorbers. and sets the minimum damping coefficient C _min as the target damping coefficient when the coefficient is the minimum damping coefficient less than C _min that can be set in the shock absorber, the target damping coefficient damping coefficient of the shock absorber of the other wheel on the diagonal By further increasing, it is possible to suppress the diagonal roll motion of the vehicle body in which the roll and the pitch motion are combined to compensate for the shortage of the damping force in the diagonal roll direction,
Since the diagonal roll motion of the vehicle body is reduced as compared with the conventional example, the stability of the vehicle can be improved.

In the second invention, the target damping coefficients of the shock absorbers of the diagonal wheels are compared, and both of the target damping coefficients on the diagonal are less than the minimum damping coefficient C _min that can be set by the shock absorber. in this case, it sets the target damping coefficient of the difference the larger the minimum damping coefficient C _min and a target damping coefficient to the minimum damping coefficient C _min, minimum attenuation and the other target damping coefficient on the diagonal of the shock absorber Coefficient C
_By increasing it above min, the diagonal roll motion generated on the vehicle body is suppressed by compensating for the lack of the damping force in the diagonal roll direction even when the diagonal wheels ride on protrusions or steps with different heights As a result, the diagonal roll motion of the vehicle body is reduced as compared with the conventional example, so that the stability of the vehicle can be improved.

According to a third aspect of the present invention, the diagonal roll damping correction means calculates a shortage of the damping force of the vehicle body in the diagonal roll direction based on a difference between the target damping coefficients of the shock absorbers on the diagonal. diagonal roll damping correction factor C ₂ calculated in accordance with the shortage of the diagonal roll damping force, the target damping coefficient of the other shock absorber on the diagonal with respect to the shock absorber which is set to the minimum damping coefficient C _min By adding, the lack of damping force in the diagonal roll direction can be compensated to suppress the movement of the vehicle body in the diagonal roll direction, and the diagonal roll movement of the vehicle body is reduced as compared with the conventional example. Therefore, it is possible to improve the stability and maneuverability of the vehicle.

In a fourth aspect of the present invention, the correction coefficient calculating means calculates a difference between a target attenuation coefficient and the minimum attenuation coefficient C _min on a diagonal, and further calculates a difference between the target attenuation coefficients on a diagonal. for adding the roll damping correction factor C ₂ computed in the target damping coefficient, it is possible to reliably suppress the movement of the vehicle body diagonal roll direction, as compared with the prior art diagonal rolling motion of the vehicle body reducing Te Therefore, the stability of the vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a vehicle showing an embodiment of the present invention.

FIG. 2 is a block diagram.

FIG. 3 is a schematic diagram of an acceleration sensor.

FIG. 4 is a characteristic diagram of the acceleration sensor.

FIG. 5 is a schematic plan view of a vehicle body showing an arrangement of an acceleration sensor.

FIG. 6 is a schematic diagram of a vehicle height sensor.

FIG. 7 is a characteristic diagram of the vehicle height sensor.

FIG. 8 is a cross-sectional view of the shock absorber.

FIG. 9 is an enlarged view of a portion A in FIG. 8;

FIG. 10 shows the relationship between the position of the spool and the oil passage, and (A)
FIG. 4 is a cross-sectional view of a spool, and FIG. 4B is an explanatory view showing a relationship between a pressure side oil passage and a circular oil passage.

FIG. 11 is an explanatory view showing a state of adjustment of a damping force, and FIG.
Shows the state of the extension side; hard, pressure side; soft, (B) shows the state of the extension side and the compression side are both soft, and (C) shows the state of the extension side;

FIG. 12 is a flowchart illustrating an example of control.

FIG. 13 is a flowchart for calculating a diagonal roll attenuation correction coefficient.

FIG. 14 is a roll direction model showing a state in which the right front wheel rides on a protrusion.

FIG. 15 is a pitch-direction model showing a state in which the right front wheel rides on a protrusion.

FIG. 16 is a claim correspondence diagram corresponding to any one of the first to fourth inventions.

[Explanation of symbols]

 2FR ~ 2RL Wheel 3FR ~ 3RL Shock absorber 5FR ~ 5RL Vehicle height sensor 6FR ~ 6R Acceleration sensor 7FR ~ 7FR Actuator 10 Controller 30 Control rod 33A, 33B, 33C Oil passage 34 Spool 35 Compression oil passage 36 Compression oil passage 37 Expansion oil Road 38 Extension oil path

Claims (4)

(57) [Claims] A shock absorber having damping coefficient changing means interposed between a sprung portion and a unsprung portion of each wheel to change a damping coefficient; Bar to detect
Absolute absolute speed detecting means ; Relative speed detecting means for detecting the relative speed in the vehicle body vertical direction with respect to the unsprung spring of each wheel; Based on the detected values of the sprung absolute speed detecting means and the relative speed detecting means. A suspension control device for a vehicle having a target damping coefficient of the shock absorber and control means for driving the damping coefficient changing means such that the damping coefficient of the shock absorber matches the target damping coefficient. Comparing means for comparing a target damping coefficient of a diagonal wheel with a minimum damping coefficient C _min that can be set by a shock absorber; and, based on the comparison result, at least one target damping coefficient that can be set by a shock absorber. When the damping coefficient is less than _{Cmin, the} minimum damping coefficient _Cmin
And a diagonal roll damping correction means for setting the target damping coefficient of the shock absorber of the other wheel on the diagonal to be larger than the target damping coefficient. apparatus. 2. A shock absorber having damping coefficient changing means interposed between a sprung portion and a unsprung portion of each wheel to change a damping coefficient; Bar to detect
Absolute absolute speed detecting means ; Relative speed detecting means for detecting the relative speed in the vehicle body vertical direction with respect to the unsprung spring of each wheel; Based on the detected values of the sprung absolute speed detecting means and the relative speed detecting means. A suspension control device for a vehicle having a target damping coefficient of the shock absorber and control means for driving the damping coefficient changing means such that the damping coefficient of the shock absorber matches the target damping coefficient. Comparing means for comparing the target damping coefficient with a minimum damping coefficient C _min that can be set by the shock absorber; and, when the target damping coefficient of the diagonally-adjusted wheel is smaller than the minimum damping coefficient C _min based on the comparison result. The target damping coefficient having the larger difference between the minimum damping coefficient _Cmin and the target damping coefficient is set as the minimum damping coefficient _Cmin. ,
A diagonal roll damping correction means for increasing a target damping coefficient of the other shock absorber diagonally from a minimum damping coefficient _Cmin . 3. The diagonal roll damping force calculating means calculates a shortage of the diagonal roll damping force of the vehicle body based on the target damping coefficient of the shock absorber on the diagonal. When the correction coefficient calculating means for calculating a diagonal roll damping correction factor C ₂ in accordance with the shortage of the diagonal roll damping force, said the diagonal roll damping correction coefficient C ₂ is added to the target damping coefficient 3. The suspension control device for a vehicle according to claim 1, further comprising an adder for increasing a target damping coefficient. 4. The correction coefficient calculation means compares the difference between the target attenuation coefficient and the attenuation coefficient of the minimum attenuation coefficient C _{min in} a diagonal direction, and calculates a diagonal value corresponding to the difference in the diagonal attenuation coefficient. suspension control apparatus for a vehicle according to claim 3, characterized in that for calculating the roll damping correction factor C _2.