JPH08244432A - Suspension control device for vehicle - Google Patents

Abstract

PURPOSE: To suppress transmission of vibration to a sprung mass while vibration of an unsprung mass is suppressed securely. CONSTITUTION: A suspension control device for vehicle is provided with a shock absorber 3 with a damping coefficient change means 51 which is provided between a sprung mass and an unsprung mass and changes a damping coefficient, a control means 54 which drives the damping coefficient change means 51 so that the damping coefficient C of the shock absorber becomes a specified target value, a sprung mass motion state detector means 52 which detects the direction and speed of the sprung mass in vertical direction of a body, and an unsprung motion state detector means 53 which detects the direction and speed of the unsprung mass in vertical direction of the body. Also the control means 54 reduces the damping coefficient C when the directions of vertical motion of the sprung mass and the unsprung mass detected by the sprung mass and unsprung mass motion state detector means, respectively, are identical to each other. On the other band, when the direction of vertical motion of the sprung mass is different from that of the unsprung mass, the damping coefficient C is increased in proportion to the absolute speed value of the unsprung mass in the vertical direction of the body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device capable of changing a damping coefficient of a vehicle shack absorber.

[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 ground contact property of the wheels and the riding comfort, and the damping coefficient of the shock absorber is adjusted. Variable control is known, and for example, there is a device disclosed in Japanese Patent Laid-Open No. 5-155222.

This is because when adjusting the damping coefficient so as to suppress the vertical motion of the sprung body (vehicle body) in response to the vibration input from the road surface, the damping coefficient is added in consideration of the vibration suppression of the unsprung body (wheel). The target value is set, and the lowering of the grounding property at the vibration frequency near the unsprung resonance point is suppressed.

[0004]

However, in the above-mentioned conventional suspension control device, when the damping coefficient of the shock absorber is increased to suppress unsprung vibration, the vibration is transmitted from unsprung to sprung. It is not taken into consideration that the force also increases. For example, when riding on a step, if the vertical motion direction on the spring and the vertical motion direction under the spring match, increasing the damping coefficient promotes vibration on the spring. As a result, the occupant may feel that the vehicle body 1 is being pushed up, which may reduce the riding comfort of the vehicle.

Therefore, the present invention has been made in view of the above problems, and a suspension of a vehicle capable of improving the riding comfort by suppressing the transmission of the vibration onto the spring while reliably suppressing the vibration under the spring. An object is to provide a control device.

[0006]

A first invention, as shown in FIG. 25, is a shock absorber provided with a damping coefficient changing means 51 which is interposed between a sprung portion and an unsprung portion to change the damping coefficient. 3 and a control means 54 for driving the damping coefficient changing means 51 so that the damping coefficient C of the shock absorber reaches a predetermined target value. The unsprung motion state detecting means 52 for detecting, and the unsprung motion state detecting means 5 for detecting the unsprung body vertical movement direction.
3, the control means 54 decreases the damping coefficient C when the vertical motion direction on the spring and the vertical motion direction on the unsprung part detected by the sprung and unsprung motion state detecting means coincide with each other.

In a second aspect based on the first aspect, the unsprung motion state detecting means 53 detects the velocity in addition to the unsprung body vertical movement direction, and the control means is When the vertical motion direction on the spring and the vertical motion direction on the unsprung are different, the damping coefficient C is increased in proportion to the absolute value of the unsprung body vertical speed.

Further, the third invention is, as shown in FIG. 25, a shock absorber 3 provided with damping coefficient changing means for changing the damping coefficient which is interposed between the sprung portion and the unsprung portion.
And a control means 54 for driving the damping coefficient changing means 51 so that the damping coefficient C of the shock absorber 3 becomes a predetermined target value. An unsprung motion state detecting means 52 for detecting speed and an unsprung body moving direction in unsprung body direction and a unsprung motion state detecting means 53 for detecting speed are provided. A damping coefficient C that is proportional to the product of the velocity and the velocity of the unsprung body in the vertical direction is set.

According to a fourth aspect of the present invention, in the third aspect, the control means gives the product of the velocity of the vehicle body in the vertical direction above the spring and the velocity of the vehicle body in the vertical direction below the spring to a code corresponding to the direction of movement. , If the sign of this product is positive, the damping coefficient C is decreased.

A fifth aspect of the present invention is the first to fourth aspects of the invention.
In any one of the inventions described above, the control means reduces the decrease of the damping coefficient C to a predetermined minimum value Cmin which can be set by the damping coefficient changing means.

As shown in FIG. 25, the sixth invention is based on any one of the second to fifth inventions, wherein the control means is a detection value of the sprung and unsprung motion state detecting means. Is provided with a means 55 for calculating the skyhook damper damping coefficient Cs, and the sum of the skyhook damper damping coefficient Cs and the damping coefficient C is output as the damping coefficient C.

A seventh invention is the second to sixth inventions.
In any one of the inventions, the unsprung motion state detecting means detects a sum of a relative speed of the sprung and unsprung bodies in the vertical direction of the vehicle body and a vertical speed of the vehicle body on the spring as the vehicle vertical direction speed of the unsprung body. To do.

[0013]

Therefore, according to the first aspect of the present invention, when the motion directions in the vertical direction of the vehicle body detected by the sprung and unsprung motion state detecting means are the same on the sprung and unsprung parts, the control means sets the damping coefficient C. And the damping coefficient changing means is driven to reduce the damping coefficient C of the shock absorber. Therefore, the vibration transmission force from the unsprung to the sprung when riding on a step is reduced and the acceleration generated on the spring is reduced. Can be reduced and the riding comfort of the vehicle can be improved.

Further, in the second aspect of the invention, when the sprung and unsprung body vertical movement directions are different, the damping coefficient C increases in proportion to the absolute value of the unsprung body vertical velocity.
While suppressing the vibration transmission force on the spring, it is possible to surely suppress the vibration under the spring and improve the ground contact under the spring.

In the third aspect of the invention, the control means sets the damping coefficient C proportional to the product of the speed in the vertical direction of the vehicle body above the spring and the speed in the vertical direction of the vehicle body below the spring. The damping coefficient C increases as the speed increases,
Unsprung vibration can be reliably performed.

According to a fourth aspect of the present invention, the product of the speed in the vertical direction of the vehicle body above the spring and the speed in the vertical direction of the vehicle body below the spring is given a sign according to the direction of movement, and if the product sign is positive, Since the control means reduces the damping coefficient C, the vibration transmission force from the unsprung portion to the sprung portion is reduced to reduce the acceleration generated on the sprung portion by climbing on a step where the motion directions of the sprung member and the unsprung member match. Therefore, the riding comfort of the vehicle can be improved.

According to a fifth aspect of the invention, the control means reduces the decrease of the damping coefficient C to a predetermined minimum value Cmin which is mechanically limited by the damping coefficient changing means, so that the unsprung portion when climbing a step is reached. The vibration transmission force on the spring can be reduced, the acceleration generated on the spring can be reduced, and the riding comfort of the vehicle can be improved.

According to a sixth aspect of the invention, the control means adds the calculated damping coefficient C to the skyhook damper damping coefficient Cs calculated from the sprung and unsprung motion state detecting means as the damping coefficient C. Since it is output to the damping coefficient changing means calculation, the sprung mass and unsprung mass can be reliably damped, and the unsprung ground contact property and riding comfort can be improved.

According to a seventh aspect of the present invention, the unsprung motion state detecting means comprises a relative speed in the vertical direction of the vehicle body above and below the spring,
Since the sum of the vehicle up-and-down speeds on the springs is taken as the unsprung body up-and-down speeds, the unsprung speeds can be easily obtained from the relative speeds of the sprung and unsprung parts and the sprung speeds. The configuration of can be simplified.

[0020]

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

As shown in FIG. 1, each wheel 2FL to 2RR.
A shock absorber 3 and a spring 4 are respectively interposed between the vehicle body 1 and the vehicle body 1, and the vehicle body 1 is sprung on the wheels 2FL to 2R.
R constitutes the unsprung part. 2FL is the front left wheel, 2FR
Indicates the right front wheel, 2RL indicates the left rear wheel, and 2RR indicates the right rear wheel, respectively.

The shock absorber 3 is provided with a damping force adjusting mechanism 7 as a damping coefficient changing means for changing the damping coefficient. For example, as disclosed in Japanese Patent Laid-Open No. 4-258541, the shock absorber 3 moves between electrodes. By utilizing that the viscosity of the electrorheological fluid changes in accordance with the voltage applied to the electrode, the damping coefficient can be made stepless and can respond to unsprung vibration control with high responsiveness. . The damping force adjusting mechanism 7 may be one that changes the orifice or valve of the hydraulic oil passage as in the conventionally used damping coefficient varying mechanism as long as it can ensure responsiveness.

At predetermined positions of the vehicle body 1 corresponding to the respective wheels 2FL to 2RR, acceleration sensors 6FL to 6RR for detecting vertical acceleration on the spring and relative displacement between the sprung and unsprung, that is, the vehicle body. 1 and the stroke sensors 5FL to 5RR for detecting the relative displacement of the wheels 2FL to 2RR are respectively provided as sprung and unsprung motion state detecting means, and signals from these sensors are input to a controller 10 mainly including a microcomputer. It

Here, the stroke sensors 5FL to 5RR
Is composed of, for example, a potentiometer, and the base ends of the connecting rods 22B are coupled to the shafts of the stroke sensors 5FL to 5RR as shown in FIG.
.About.2RR is connected to the middle of the arm 21 that swingably supports the free end of the connecting rod 22B via the connecting rod 22A, and the wheels 2FL to 2RR and the vehicle body 1 are connected.
The relative displacement in the vertical direction of is captured as an angle change.

The controller 10 calculates the target value of the damping coefficient based on the vertical acceleration and the relative displacement of the vehicle body 1 detected by these sensors, and controls the damping force adjusting mechanism 7 according to the target damping coefficient. Is output to change the damping coefficient of the shock absorber 3.

A block diagram of the controller 10 is shown in FIG. 3, and the stroke sensors 5FL to 5RR and the acceleration sensor 6 are included.
Signals from FL to 6RR are input interface circuit 1
11. After being converted into a digital signal via the A / D converter 112, the signal is input to the microcomputer 100.

The vertical acceleration Z _Gi "(subscript" i "indicates each wheel, i = FL, FR, RL, RR, the same applies hereinafter) of the vehicle body 1 detected by the acceleration sensors 6FL to 6RR is sprung speed detection. It is integrated in the unit 101 and converted into a velocity Z _Gi ′ in the vertical direction of the vehicle body on the spring.

Relative displacement H in the vertical direction between the vehicle body 1 and the wheels 2FL to 2RR detected by the stroke sensors 5FL to 5RR.
_Di is differentiated by the unsprung speed detection unit 102 and converted into a relative speed, and then the unsprung speed X is obtained by adding the unsprung speed Z _Gi '
Calculated as _Gi '.

Then, on the basis of the sprung _mass velocity Z _Gi ′ and the unsprung _mass velocity X _Gi ′, the damping coefficient computing unit computes the damping coefficient C by the calculation described later.

The damping coefficient C thus obtained is converted into an analog signal via the D / A converter 113 and the driver circuit 114, amplified, and then output to the damping force adjusting mechanism 7 of the shock absorber 3 as a control voltage Vi. .

FIG. 4 is a flow chart showing an example of the control performed by the controller 10, which is executed at predetermined time intervals by timer interruption or the like, and will be described in detail below with reference to this flow chart.

In step S1, the acceleration sensors 6FL-6FL
The vertical acceleration Z _Gi ″ of the vehicle body 1 detected by the RR is read, and the vehicle body 1 and the wheels 2FL to 2R detected by the stroke sensors 5FL to 5FR in step S2.
Read the relative displacement H _{Di of} R.

In step S3, the vertical sprung velocity Z _Gi 'corresponding to each wheel 2FL to 2RR is calculated by integrating the acceleration Z _Gi ", and in step S4, the relative displacement H _Di is differentiated. The relative speed H _Di 'of the sprung part and the unsprung part is calculated by.

Then, in step S5, the unsprung speed X _Gi ′ which is the absolute unsprung vertical speed is added by adding the sprung speed Z _Gi ′ obtained in step S3 to this relative displacement H _Di ′. Calculate

In step S6, the damping coefficient C of the shock absorber 3 is calculated based on the sprung _mass velocity Z _Gi 'and the unsprung _mass velocity X _Gi ' obtained in this way.

First, depending on the sign of the multiplication result of the sprung _mass velocity Z _Gi 'and the unsprung _mass velocity X _Gi ', case classification is performed as follows.

(A) Z _Gi '× X _Gi '<0 When the directions of movement of the sprung and unsprung are different.

(B) Z _Gi '× X _Gi '> 0 When the sprung and unsprung motion directions are the same.

When the sprung and unsprung motion directions are different, the damping coefficient Ci is calculated based on the following equation (1).

C _i = Cu × | X _Gi '| (1) However, Cu is a predetermined constant, and the damping coefficient C _i is obtained by multiplying the absolute value of the unsprung speed X _Gi ' by the constant Cu.

On the other hand, when the sprung and unsprung movement directions are the same, the damping coefficient C _i is set to the minimum value Cmin that can be set by the damping force adjusting mechanism 7.

In this way, each wheel 2FL, which is obtained according to the magnitudes of the sprung and unsprung motion directions and the unsprung speed X _Gi '
The 2RR damping coefficient C _i is converted to the command voltage V _i by the function f (C _i ) set in advance in step S7. Note that the conversion from the damping coefficient C _i to the command voltage V _i can be performed by a map or an approximate expression that is obtained in advance by experiments or the like.

In step S8, each wheel 2FL to 2RR is
The command voltage V _i is sent to each of the damping force adjusting mechanisms 7 and the shock absorber 3 is changed to the damping coefficient C according to the command voltage V _i .

By repeating the above steps S1 to S8 every predetermined time, the damping coefficient C of the shock absorber 3 is increased.
Is set to a different value depending on the direction of motion of the sprung and unsprung parts. When this direction of motion is the same, the minimum damping coefficient Cmi
If the motion direction is different from n, the absolute value of the unsprung velocity |
The value is set according to X _Gi '|.

Now, assuming that the suspension of the vehicle is a one-wheel model as shown in FIG. 5, the sprung displacement X ₂ (absolute displacement) and the sprung acceleration Z when riding on a step such as a curbstone.
_Gi ", unsprung displacement X ₁ (absolute displacement), the relationship between the damping coefficient C and the time is shown in FIGS. 6-9. In the drawing, broken lines indicate by the prior art.

When riding on a step, the vertical movement direction above the spring and the vertical movement direction below the spring substantially coincide with each other. Therefore, as shown in FIG. 9, the damping coefficient C is predetermined according to the coincidence of this movement direction. Becomes the minimum value Cmin, and the damping force generated by the shock absorber 3 is changed to the minimum value. Therefore, the transmission force of the vibration from the unsprung portion to the sprung portion is reduced, and as shown in FIG. 7, the maximum value of the acceleration Z _Gi ″ generated on the sprung portion is reduced as compared with the conventional example. Since it is possible to suppress the push-up of the vehicle body 1 and the like, it is possible to improve the riding comfort of the vehicle.

On the other hand, in a section in which the vertical motion direction on the spring and the vertical motion direction on the unsprung are different, a damping coefficient C proportional to the magnitude of the absolute value of the unsprung speed X _Gi 'is given, so that The vibration can be reliably controlled.

By the way, the damping force F of the shock absorber 3 is generated by the relative motion of the unsprung portion with respect to the sprung portion, and is expressed by F = C × (X _G '-Z _G ') (2).

When the unsprung portion is vibrating slightly (such as fluttering), the damping force F is as follows because the sprung portion velocity Z _Gi ′ is relatively smaller than the unsprung portion velocity X _Gi ′. Can be thought of as.

[0050] _{F = C × X G '...} (3) that is, the relative speed H _D on the unsprung spring' for smaller damping force F generated when a small vibration damping effect by reducing the damping coefficient C it can reduce the transmission force of vibration of small things, whereas, it is possible to enhance the damping effect by generating a large damping force F by increasing the damping coefficient C when the relative velocity H _D 'is large.

Therefore, when the vertical movement direction on the spring does not match the vertical movement direction on the unsprung, the damping coefficient C of the shock absorber 3 is set to a value proportional to the absolute value of the unsprung speed X _Gi '. it is, 'while performing vibration effectively unsprung generates a large damping force F when is large, unsprung velocity X _Gi' relative velocity H _D on and unsprung spring when the small damping coefficient C Is set to a small value to suppress an unnecessary increase in the damping force F, and the vibration transmission force from the unsprung portion to the sprung portion can be reduced to achieve both unsprung vibration suppression and ride comfort. When the upward and downward movement directions are the same as the unsprung upward and downward movement directions, the damping coefficient C is set to the minimum value Cmin to suppress the push-up of the vehicle body 1 that occurs when riding on a step, and to improve the riding comfort of the vehicle. It is possible to improve the Than it is.

FIG. 10 shows a second embodiment, in which the calculation of the damping coefficient C in the first embodiment is changed, and other configurations are the same as those in the first embodiment.

In FIG. 10, steps S11 to S15
And steps S17 to S18 are the same as those in the first embodiment shown in FIG.
Steps S1 to S5 and S7 of the flowchart shown in FIG.
.About.S8, only step S17 for calculating the damping coefficient C is changed.

The damping coefficient C _i is obtained by multiplying the product of the unsprung speed X _Gi ′ and the sprung speed Z _Gi ′ by a predetermined constant −Cu as in the following equation.

C _i = −Cu × X _Gi ′ × Z _Gi ′ (4) The damping coefficient C _i is positive when the sprung and unsprung vertical movement directions are different, while this vertical movement direction is If they are the same, it will be negative. Here, when the damping coefficient C _i becomes negative, the damping coefficient C _i is set to a predetermined minimum value Cmin.

Similar to the first embodiment, assuming that the suspension of the vehicle is a one-wheel model as shown in FIG. 5, the sprung displacement X ₂ (absolute displacement) when the vehicle rides on a step such as a curb, the spring The relationship between the upper acceleration Z _Gi ″, the unsprung displacement X ₁ (absolute displacement), the damping coefficient C and time is shown in FIGS. 11 to 14. The broken line in the figure shows the conventional one.

Immediately after riding on the step, the vertical motion direction on the spring and the vertical motion direction on the unsprung spring match, so that the damping coefficient C _i has a predetermined minimum value Cm depending on the matching of the motion directions.
When it becomes in, the damping force generated by the shock absorber 3 is changed to the minimum value Cmin. Therefore, the transmission force of the vibration from the unsprung portion to the sprung portion is reduced, and the maximum value of the acceleration Z _Gi ″ generated on the sprung portion is reduced as compared with the conventional example as shown in FIGS. On the other hand, in a section in which the vertical motion direction on the spring and the vertical motion direction on the unsprung are different, the damping coefficient C is proportional to the product of the unsprung speed X _Gi 'and the sprung speed Z _Gi '.
_{Since i} increases, it is possible to surely suppress unsprung vibration as shown in FIG. 13, and it is not necessary to distinguish cases depending on the sprung and unsprung motion directions as in the first embodiment. The calculation can be simplified.

FIG. 15 shows the third embodiment, in which the skyhook damper control is incorporated in the calculation of the damping coefficient C in the first embodiment, and the other construction is the same as in the first embodiment.

In FIG. 15, steps S21 to S25.
And steps S28 to S29 are the same as those in the first embodiment shown in FIG.
Steps S1 to S5 and S7 of the flowchart shown in FIG.
Is the same as S8 to S8, the step S26 for calculating the damping coefficient Co based on the skyhook damper control is added, and the step S27 for calculating the damping coefficient C is changed.

The damping coefficient C _i is divided into cases according to the vertical movement directions of the sprung and unsprung portions in the same manner as in the first embodiment. If they are different, the absolute value of unsprung speed X _Gi 'and a predetermined constant C
It is assumed that the coefficient multiplied by u is added with the damping coefficient Co by the skyhook damper control. On the other hand, when the vertical movement directions match, the damping coefficient Co by the skyhook damper control is added.
The damping coefficient Ci is defined by only

C _i = Cu × | X _Gi ′ | + Co Z _Gi ′ × X _Gi ′ <0 C _i = Co Z _Gi ′ × X _Gi ′> 0 (5) Here, the damping coefficient by skyhook damper control Co
Is obtained from the unsprung speed X _Gi ′ and the unsprung speed Z _Gi ′ by the following equation.

Co = −Cs × Z _Gi ′ / (X _Gi ′ −Z _Gi ′) (6) Note that Cs represents the damping constant of the skyhook damper. (Published by Sankaido March 30, 1991), pages 244 to 250, and also disclosed in JP-A-60-248419.

The damping coefficient C _i is a value obtained by adding the skyhook damper damping coefficient Co to a value proportional to the absolute value of the unsprung speed X _Gi 'when the vertical motion directions of the sprung and unsprung are different. while the C _i, the damping coefficient C _i when the vertical movement direction of the same is only skyhook damper damping coefficient Co as a minimum value.

Similar to the first embodiment, assuming that the suspension of the vehicle is a one-wheel model as shown in FIG. 5, the sprung displacement X ₂ (absolute displacement) when the vehicle rides on a step such as a curb, the spring 16 to 19 show the relationship between the upper acceleration Z _Gi ″, the unsprung displacement X ₁ (absolute displacement), the damping coefficient C, and time. Incidentally, the broken line in the figure shows the conventional one.

Immediately after riding on the step, the vertical motion direction on the spring and the vertical motion direction on the unsprung spring match, so that the damping coefficient C _i is a predetermined minimum value depending on the matching of the motion directions. The damper damping coefficient Co is set to reduce the transmission force of vibration from the unsprung portion to the sprung portion. On the other hand, when the vertical movement direction is different, the damping coefficient C _i increases to effectively suppress the unsprung portion. As shown in FIG. 16 and FIG. 17, the maximum value of the acceleration Z _Gi ″ generated on the spring is reduced as compared with the conventional example, while the unsprung vibration is surely performed as shown in FIG. Suppress it.

By using the skyhook damper control, as shown in FIGS. 18 and 19, the damping coefficient C _i is increased after the time T ₁ when the vibration under the spring becomes small. The unsprung and unsprung vibrations can be suppressed without deteriorating the vibration transmission force, and it is possible to ensure both the ground contact of the wheels and the improvement of riding comfort and stability.

FIG. 20 shows a fourth embodiment, in which the calculation of the damping coefficient C in the third embodiment is changed, and other configurations are the same as those in the first embodiment.

In FIG. 20, steps S31 to S26.
And steps S38 to S39 are the same as those in the third embodiment shown in FIG.
It is the same as steps S21 to S26 and S28 to S29 of the flowchart shown in FIG. 5, and is a modification of step S37 for calculating the damping coefficient C.

The damping coefficient C _i is (4) in the second embodiment.
The same as the third embodiment, except that the skyhook damper damping coefficient Co is added, the unsprung speed X _Gi '
And the sprung speed Z _Gi ′ multiplied by a predetermined constant −Cu, and the skyhook damper damping coefficient Co is added.

C _i = −Cu × X _Gi ′ × Z _Gi ′ + Co (7) The damping coefficient C _i becomes positive when the sprung and unsprung vertical movement directions are different, while the vertical movement direction is When the values are the same, the first term of the above formula (7) becomes negative and Co obtained by the above formula (6) also becomes negative, but the negative damping coefficient C _i is the damping force adjustment of the shock absorber 3. Since it cannot be realized by the mechanism 7, the minimum feasible damping coefficient Cmin is set.

The damping coefficient C _i is the unsprung speed X _Gi 'when the vertical motion directions of the sprung and unsprung are different as in the following equation.
And the sprung speed Z _Gi 'increases in proportion to the product, and when the vertical motion directions match, the damping coefficient C _i is the minimum value C m.
Becomes in to reduce the vibration transmission force from the unsprung to the sprung.

Similar to the first embodiment, assuming that the suspension of the vehicle is a one-wheel model as shown in FIG. 5, the sprung displacement X ₂ (absolute displacement) when the vehicle rides on a step such as a curb, the spring The relationship between the upper acceleration Z _Gi ″, the unsprung displacement X ₁ (absolute displacement), the damping coefficient C and time is shown in FIGS. 21 to 24. The broken line in the figure indicates that according to the conventional example.

As in the second embodiment, immediately after riding on a step, the vertical motion direction on the spring and the vertical motion direction on the unsprung spring match, so the damping coefficient C _i depends on the matching of this motion direction. Is set to a predetermined minimum value Cmin to reduce the transmission force of the vibration from the unsprung to the sprung, but when the vertical movement direction is different, the sprung speed Z _Gi 'and the unsprung speed X
_The damping coefficient C _i increases in proportion to the product of _Gi ′, and the unsprung vibration can be effectively suppressed. As shown in FIGS. 21 and 22, the acceleration Z _Gi ″ and the amplitude generated on the spring are increased. 23, the vibration under the spring is surely suppressed as shown in FIG. 23 while being reduced as compared with the conventional example.

In addition, by using the skyhook damper control, as shown in FIGS. 23 and 24, the damping coefficient Ci is increased after the time T ₁ 'when the vibration under the spring becomes small, so that the spring is moved upward. It is possible to perform unsprung and unsprung vibration suppression without deteriorating the vibration transmission force of
It is possible to ensure both the grounding property of the wheels and the improvement of riding comfort and stability.

[0075]

As described above, according to the first aspect of the present invention, the shock absorber is provided between the sprung portion and the unsprung portion and has the damping coefficient changing means for changing the damping coefficient, and the damping of the shock absorber. In a suspension control device for a vehicle, which has a control means for driving the damping coefficient changing means so that the coefficient C reaches a predetermined target value, a sprung motion state detecting means for detecting a vertical moving direction of the vehicle body on the spring, An unsprung motion state detecting means for detecting an unsprung body vertical movement direction is provided, and the control means includes an unsprung vertical movement direction and an unsprung motion direction detected by the sprung and unsprung motion state detecting means. The damping coefficient C is reduced when the vertical movement directions of the springs coincide with each other, and the vibration transmission force from the unsprung to the sprung when riding on a step or the like can be reduced to reliably suppress the sprung mass. It is possible to improve the riding comfort of the vehicle in such as when riding up on the step.

According to a second aspect of the present invention, the unsprung motion state detecting means detects the speed in addition to the unsprung body vertical movement direction, and the control means detects the unsprung vertical movement direction. When the unsprung vertical movement direction is different, the damping coefficient C is increased in proportion to the absolute value of the unsprung vehicle body vertical direction velocity, and when the unsprung and unsprung vehicle body vertical movement directions are different, The damping coefficient C can be increased in proportion to the absolute value of the vertical speed to reliably perform unsprung vibration suppression and improve unsprung ground contact, thus achieving both vehicle stability and riding comfort. Can be made.

In the third aspect of the invention, the shock absorber is provided between the sprung portion and the unsprung portion to change the damping coefficient, and the damping coefficient C of the shock absorber is predetermined. In a suspension control device for a vehicle, which has a control means for driving the damping coefficient changing means so as to obtain a target value, a sprung body motion state detecting means for detecting a moving direction and a speed in a vertical direction of a vehicle body on a spring, and an unsprung body An unsprung motion state detecting means for detecting a moving direction and a speed in a vertical direction of the vehicle body is provided, and the control means sets a damping coefficient C proportional to a product of a vehicle vertical direction speed on the spring and an unsprung vehicle vertical direction speed. The damping coefficient C that is set and is proportional to the product of the sprung and unsprung body velocities in the vertical direction can reliably perform unsprung vibration suppression, and improve the grounding property of the wheel.

According to a fourth aspect of the present invention, the control means assigns a sign according to the direction of movement to the product of the speed in the vertical direction of the body on the spring and the speed in the vertical direction of the body under the spring, and the sign of the product is positive. In the case of, the damping coefficient C is reduced and the vibration transmission force from the unsprung to the sprung when riding on a step is reduced to improve the riding comfort of the vehicle and suppress the sprung and unsprung vibrations. It becomes possible to perform surely, and it is possible to improve both the riding comfort and stability of the vehicle.

In the fifth aspect of the invention, the control means reduces the decrease of the damping coefficient C to a predetermined minimum value Cmin which can be set by the damping coefficient changing means. It is possible to reduce the vibration transmission force to the vehicle, reduce the acceleration generated on the spring, and improve the riding comfort of the vehicle.

According to a sixth aspect of the invention, the control means comprises means for calculating a skyhook damper damping coefficient Cs from the detection values of the sprung and unsprung motion state detecting means, and the skyhook damper damping coefficient Cs. By calculating the sum of the above and the damping coefficient C as the damping coefficient C, the sprung mass and the unsprung mass can be reliably suppressed, and the stability of the vehicle and the riding comfort can be improved at the same time.

According to a seventh aspect of the invention, the unsprung motion state detecting means is configured such that the sum of the relative speeds of the sprung and unsprung parts in the vertical direction of the vehicle body and the speed of the unsprung body in the vertical direction of the vehicle body is measured in the unsprung body vertical direction. Since the unsprung speed is detected as the speed, it is possible to easily obtain the unsprung speed from the sprung and unsprung relative speeds and the sprung speed, and it is possible to simplify the configuration of the device and reduce the manufacturing cost. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a stroke sensor of the same.

FIG. 3 is a block diagram of the controller.

FIG. 4 is a flowchart showing an example of control performed by a controller.

FIG. 5 is a schematic diagram showing a control model of the same.

FIG. 6 is a graph showing the relationship between sprung displacement and time, where the solid line shows the present embodiment and the broken line shows the conventional example.

FIG. 7 is a graph showing the relationship between sprung vertical acceleration and time, where the solid line shows the present embodiment and the broken line shows the conventional example.

FIG. 8 is a graph showing the relationship between unsprung displacement and time, where the solid line shows the present embodiment and the broken line shows the conventional example.

FIG. 9 is a graph showing the relationship between the damping coefficient and time, where the solid line shows the present embodiment and the broken line shows the conventional example.

FIG. 10 is a control flowchart showing a second embodiment.

FIG. 11 is a graph showing the relationship between sprung displacement and time, where the solid line shows the second embodiment and the broken line shows the conventional example.

FIG. 12 is a graph showing the relationship between sprung vertical acceleration and time, where the solid line shows the second example and the broken line shows the conventional example.

FIG. 13 is a graph showing the relationship between unsprung displacement and time, where the solid line shows the second embodiment and the broken line shows the conventional example.

FIG. 14 is a graph showing the relationship between the damping coefficient and time, where the solid line shows the second example and the broken line shows the conventional example.

FIG. 15 is a flowchart of control showing the third embodiment.

FIG. 16 is a graph showing the relationship between sprung displacement and time, where the solid line shows the third embodiment and the broken line shows the conventional example.

FIG. 17 is a graph showing the relationship between sprung vertical acceleration and time, where the solid line shows the third example and the broken line shows the conventional example.

FIG. 18 is a graph showing the relationship between unsprung displacement and time, where the solid line shows the third example and the broken line shows the conventional example.

FIG. 19 is a graph showing the relationship between the damping coefficient and time, where the solid line shows the third example and the broken line shows the conventional example.

FIG. 20 is a flowchart of control showing the fourth embodiment.

FIG. 21 is a graph showing the relationship between sprung displacement and time, where the solid line shows the fourth example and the broken line shows the conventional example.

FIG. 22 is a graph showing the relationship between sprung vertical acceleration and time, where the solid line shows the fourth example and the broken line shows the conventional example.

FIG. 23 is a graph showing the relationship between unsprung displacement and time, where the solid line shows the fourth example and the broken line shows the conventional example.

FIG. 24 is a graph showing the relationship between the damping coefficient and time, where the solid line shows the fourth example and the broken line shows the conventional example.

FIG. 25 is a claim correspondence diagram corresponding to the first to sixth inventions.

[Explanation of symbols]

 1 Vehicle Body 2FL to 2RR Wheels 3 Shock Absorber 4 Spring 5 Stroke Sensor 6 Acceleration Sensor 7 Damping Force Adjusting Device 10 Controller 51 Damping Coefficient Changing Means 52 Sprung Motion State Detection Means 53 Unsprung Movement State Detection Means 54 Control Means

Claims (7)

[Claims] 1. A shock absorber provided with a damping coefficient changing means for changing the damping coefficient C, which is interposed between a sprung portion and an unsprung portion, and the damping coefficient C of the shock absorber has a predetermined target value. In a vehicle suspension control device having a control means for driving the damping coefficient changing means, a sprung body motion state detecting means for detecting a movement direction of a vehicle body in a vertical direction on a spring and a movement direction of the body body in a vertical direction of an unsprung body are detected. An unsprung motion state detection means for detecting is provided, and the control means attenuates when the vertical movement direction on the spring detected by the sprung and unsprung motion state detection means matches the unsprung vertical movement direction. A suspension control device for a vehicle, wherein the coefficient C is reduced. 2. The unsprung motion state detecting means detects speed in addition to the unsprung body vertical movement direction, and the control means controls the unsprung vertical movement direction and unsprung vertical movement direction. 2. The vehicle suspension control device according to claim 1, wherein the damping coefficient C is increased in proportion to the absolute value of the unsprung body up-down velocity when the values are different. 3. A shock absorber having a damping coefficient changing means for changing the damping coefficient C, which is interposed between the sprung portion and the unsprung portion, and the damping coefficient C of the shock absorber has a predetermined target value. In a vehicle suspension control device having a control means for driving the damping coefficient changing means, a sprung body motion state detecting means for detecting a moving direction and a speed of a vehicle body in a vertical direction on a spring, and an unsprung body vertical motion An unsprung motion state detecting means for detecting a direction and a speed is provided, and the control means controls the damping coefficient C proportional to a product of a speed of the vehicle in the vertical direction on the spring and a speed of the vehicle in the vertical direction of the unsprung body.
A suspension control device for a vehicle, wherein: 4. The control means assigns a sign according to the direction of movement to the product of the speed in the vertical direction of the vehicle body above the spring and the speed in the vertical direction of the vehicle body below the spring. If the product has a positive sign, the damping coefficient is given. The vehicle suspension control device according to claim 3, wherein C is reduced. 5. The vehicle suspension control according to claim 1, wherein the control means reduces the decrease of the damping coefficient C to a predetermined minimum value Cmin which can be set by the damping coefficient changing means. apparatus. 6. The control means comprises means for calculating a skyhook damper damping coefficient Cs from the detection values of the sprung and unsprung motion state detecting means, and the skyhook damper damping coefficient Cs and the damping coefficient C The vehicle suspension control device according to any one of claims 2 to 5, wherein the sum is output as the damping coefficient C. 7. The unsprung motion state detecting means detects the sum of the relative speed of the sprung and unsprung bodies in the vertical direction of the vehicle body and the speed of the unsprung vehicle in the vertical direction of the vehicle body as the unsprung vehicle body vertical direction speed. The suspension control device for a vehicle according to any one of claims 2 to 6, characterized in that: