JP3014813B2 - Vehicle suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system, and more particularly to an improvement in a vehicle having a shock absorber having a variable damping force characteristic between a sprung portion and a unsprung portion.

[0002]

2. Description of the Related Art Generally, a vehicle suspension system is provided with a shock absorber between a sprung portion on the vehicle body side and a unsprung portion on the wheel side to attenuate vertical vibration of the wheel. This shock absorber is of a variable damping force characteristic type, and its damping force characteristics (characteristics having different damping coefficients) can be changed between high and low two stages, and the damping force characteristics can be changed in multiple stages or steplessly continuously. There are various things.

[0003] Such a control method of a variable damping force type shock absorber is basically based on the damping force of the shock absorber when the damping force generated by the shock absorber acts in the vibration direction with respect to the vertical vibration of the vehicle body. Excitation energy transmitted to the spring by changing the damping force of the shock absorber to the high damping side (ie, the hard side) when the damping force acts on the low damping side (ie, the soft side) and the damping force acts in the damping direction. Therefore, the vibration damping energy is increased to thereby improve both the riding comfort and the running stability of the vehicle.

[0004] Various methods have been proposed for determining whether the damping force of the shock absorber acts in the vibration direction or the vibration damping direction of the sprung vertical vibration.
For example, Japanese Unexamined Patent Publication No. 60-248419 discloses a method for checking whether the sign of the relative displacement between the sprung portion and the unsprung portion and the sign of the relative speed between the sprung portion and the unsprung portion, which is a derivative thereof, match. A method is disclosed in which, when they match, the vibration direction is determined, and when they do not match, the vibration direction is determined.

[0005]

However, as described above,
Based on whether the direction of the relative displacement between the sprung and unsprung and the direction of the relative speed between the sprung and the unsprung are the same, in a damping force characteristic variable type shock absorber that changes and controls the damping force characteristic. When the damping force of the shock absorber is controlled by feedback control, the direction of the relative displacement between the sprung and unsprung and the direction of the relative speed between the sprung and the unsprung frequently coincide with each other. To repeat the mismatch,
Inevitably, there is a problem that the control computer becomes large and expensive.

In order to solve the above problem and to control the damping force of the shock absorber by open control, it is conceivable to use a step motor as an actuator. The direction of the relative displacement between the unsprung part and the direction of the relative velocity between the sprung part and the unsprung part frequently repeats and mismatches, so that the damping force is changed from the soft side to the hard side, and further from the hard side. It is necessary to drive the step motor at a very high speed, such as on the software side, so that it is changed between the software side and the hardware side. In such a case,
Since the stepping motor is heated or loses synchronism, the damping force of the shock absorber cannot be controlled as desired in accordance with the vertical vibration state of the vehicle body, and there is a problem that running stability is impaired. .

[0007] The present invention has been made in view of such a point, and an object thereof is to provide a method based on predetermined conditions.
By effectively changing the damping force characteristic of the shock absorber without deteriorating the running stability, it is intended to surely prevent the actuator from stepping out while reducing the temperature of the actuator (step motor).

[0008]

In order to achieve the above object, a solution according to the present invention is provided with a shock absorber between a sprung portion and a unsprung portion of each wheel, and a displacement on the spring. It is assumed that a vehicle suspension apparatus is configured to change and control the damping force characteristic of the shock absorber in accordance with the relative relationship between the speed and the unsprung displacement speed.
An actuator for changing a damping force characteristic of the shock absorber; control means for outputting a control signal to the actuator to operate the actuator; responsiveness detecting means for detecting an operation response speed of the actuator; And a correction means for correcting the control signal of the control means to the actuator so as to reduce the frequency of changing the damping force characteristic of the shock absorber when the signal is lower than a predetermined operation response speed. It is configured.

According to a second aspect of the present invention, there is provided a solution according to the first aspect, wherein the correcting means includes an input frequency for detecting an input frequency applied to the vehicle body. An output signal from the detecting means is input, and the output signal from the input frequency detecting means is received, and only when the signal is in a low-frequency vibration region lower than a predetermined vibration frequency, is the signal applied to the actuator. It is configured to correct the control signal of the control means.

According to a third aspect of the present invention, there is provided a control device according to the first aspect, wherein the correction unit is configured to output a signal from the responsiveness detection unit at a predetermined operation response speed. In this case, the control signal of the control means to the actuator is corrected so as to restrict the change range of the damping force characteristic of the shock absorber by the actuator at a later time.

A fourth aspect of the present invention resides in a solution according to the first aspect of the present invention, wherein the correcting means includes a signal from the responsiveness detecting means for detecting a predetermined operation response speed. The control signal of the control means to the actuator is corrected so that the damping force characteristic of the shock absorber is maintained longer at a later time.

[0012]

According to the first aspect of the present invention,
In the actuator for changing the damping force characteristic of the shock absorber, when the operation response speed detected by the response detecting means is lower than a predetermined operation response speed, a decrease in responsiveness is detected, and the damping force characteristic of the shock absorber is changed. Since the operation is performed by the control signal of the control means corrected by the correction means so as to reduce the frequency, the operation of the actuator which is changed between the software side and the hardware side at a very high speed and becomes overheated, that is, the change frequency is changed by the correction means. The temperature of the actuator can be lowered by the correction, and the step-out of the actuator can be prevented.

Further, in the invention according to claim 2, the correction means is a low frequency vibration region in which an output signal from the input frequency detection means for detecting the frequency of the input applied to the vehicle body is lower than a predetermined vibration frequency. Only when the control signal of the control means to the actuator is corrected, when the output signal from the input frequency detection means is in a high frequency vibration region higher than a predetermined vibration frequency, the control signal of the control means to the actuator is Is not corrected by the correction means, for example, the damping force characteristic of the previous time is maintained as it is, and the frequency of changing the damping force characteristic of the shock absorber is reduced, so that uncomfortable low-frequency vibration input to the vehicle body is reduced. , The temperature of the actuator can be reduced, and the step-out of the actuator can be prevented.

Further, in the invention according to claim 3, the correction means corrects the control signal of the control means to the actuator when the operation response speed of the actuator is lower than a predetermined operation response speed, thereby damping the shock absorber. Since the change range of the characteristic is restricted, the damping force characteristic of the shock absorber is restricted to, for example, a range on the hardware side for ensuring the steering stability, and the frequency of change of the actuator is reduced by the correction of the correction means. It is possible to lower the temperature of the actuator while ensuring stability and the like, and to prevent the actuator from stepping out.

Further, in the invention according to claim 4, the correction means corrects a control signal of the control means to the actuator when the operation response speed of the actuator is lower than a predetermined operation response speed, thereby damping force of the shock absorber. Long-lasting characteristics reduce the frequency of actuator changes.
Unpleasant low frequency input to the vehicle
The temperature of the actuator can be lowered while suppressing the vibration, and the step-out of the actuator can be prevented.

[0016]

As described above, according to the vehicle suspension system of the first aspect of the present invention, when the operation response speed of the actuator is lower than the predetermined operation response speed, the damping force characteristic of the shock absorber is reduced by the correction means. Since the control signal of the control means is corrected so as to reduce the frequency of change, it is possible to reliably prevent the actuator from stepping out while reducing the temperature of the overheated actuator, and to improve the running stability.

According to the vehicle suspension device of the second aspect of the present invention, the correction signal corrects the control signal of the control device to the actuator only when the input frequency applied to the vehicle body is in a low frequency vibration range. In the high frequency vibration region, the control signal of the control means to the actuator is held at the previous damping force characteristic, etc., and the frequency of changing the damping force characteristic of the shock absorber is reduced to suppress unpleasant low frequency vibration, The step-out of the actuator can be reliably prevented while lowering the temperature of the actuator.

Further, according to the vehicle suspension device of the third aspect of the present invention, when the operation response speed of the actuator is lower than the predetermined operation response speed, the correction means restricts the range of change in the damping force characteristic of the shock absorber. The control signal of the control means to the actuator has been corrected so that the damping force characteristics of the shock absorber are restricted to the range on the hardware side that ensures steering stability, and the frequency of actuator changes is reduced to reduce steering stability. As a result, step-out of the actuator can be reliably prevented while lowering the temperature of the actuator.

Further, according to the vehicle suspension apparatus of the fourth aspect of the present invention, the damping force characteristic of the shock absorber becomes longer when the operation response speed of the actuator is lower than the predetermined operation response speed by the correction means.
Since the control signal of the control means to the actuator is corrected so as to be maintained , the frequency of change of the actuator can be reduced, and the temperature of the actuator can be reduced, and the step-out of the actuator can be prevented.

[0020]

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

FIG. 1 is a schematic perspective view of a vehicle including a vehicle suspension device according to a preferred embodiment of the present invention.

Referring to FIG. 1, a vehicle suspension apparatus according to a preferred embodiment of the present invention includes shock absorbers 1, 2, 3, and 4 provided for each wheel and attenuating vertical vibration of each wheel. ing. Each of the shock absorbers 1, 2, 3, and 4 is configured to be switchable to ten different damping force characteristics having different damping coefficients by an actuator (not shown), and includes a pressure sensor (not shown). In FIG. 1, 5 is a left front wheel, 6 is a left rear wheel, and a right front wheel and a right rear wheel are not shown. 7 is each shock absorber 1, 2, 3, 4
A coil spring disposed on the outer periphery of
Is a control unit as control means for outputting a control signal to the actuators of each of the shock absorbers 1, 2, 3, and 4 to change and control the damping force characteristics of each of the shock absorbers 1, 2, 3, and 4. is there.

On the spring of the vehicle body 9, a first acceleration sensor 11, which detects the vertical acceleration of the spring of each wheel,
A second acceleration sensor 12, a third acceleration sensor 13, and a fourth acceleration sensor 14 are provided, and a vehicle speed sensor 15 for detecting a vehicle speed is provided in a meter of the instrument panel. Reference numeral 16 denotes a mode selection switch for controlling the control of the damping force characteristics of the shock absorbers 1, 2, 3, and 4 by a driver to one of a hard mode, a soft mode, and a control mode. When the hard mode is selected by the mode selection switch 16, only a damping coefficient in a range where the damping force characteristic is hard is selected, and only within that range, the shock absorbers 1, 2, 3, and 3.
The control for changing the damping force characteristic is performed. When the soft mode is selected, only the damping coefficient in a range where the damping force characteristic is soft is selected, and only within the range, the control for changing the damping force characteristics of the shock absorbers 1, 2, 3, and 4 is performed. Is made. Further, when the control mode is selected, the control for changing the damping force characteristics of the shock absorbers 1, 2, 3, and 4 is performed in a predetermined manner according to a map or a table stored in the control unit 8 in advance. Has become.

FIG. 2 is a schematic sectional view of a main part of the shock absorber 1 provided for the left front wheel. However, the pressure sensor is omitted for convenience.

In FIG. 2, the shock absorber 1 is
A cylinder 21 is provided. A piston unit 22 in which a piston and a piston rod are integrally connected is slidably fitted in the cylinder 21. The cylinder 21 and the piston unit 22 are connected unsprung and sprung, respectively.

The piston unit 22 has two orifices 23 and 24 formed therein. One orifice 2
3 is always open, and the other orifice 24 has a passage area of 10
It is formed so that it can be changed in stages.

FIG. 3 is an exploded schematic perspective view of the first actuator 41 provided on the shock absorber 1, and FIG.
And the first actuator 41 as shown in FIG.
A shaft 26 rotatably provided in a sleeve 25 fixed to the piston unit 22;
A step motor 27 for rotating the shaft 6, a first orifice plate 29 having nine circular holes 28 attached integrally to the lower end of the shaft 26 and having nine circular holes 28 along its circumference, and a lower end of the sleeve 25 integrally therewith. A second orifice plate 31 provided with an arc-shaped elongated hole 30 along the circumference thereof. Here, the nine circular holes 28 formed in the first orifice plate 29 and the long holes 30 formed in the second orifice plate 31 correspond to the rotation of the shaft 26 and the first orifice plate 29 caused by the rotation of the step motor 27. According to the nine circular holes 28
Are formed so as to be able to communicate with the elongated holes 30 in the range of 0 to 9 pieces.

The upper chamber 32 and the lower chamber 33 in the cylinder 21
The inside is filled with a fluid having a predetermined viscosity, and can move between the upper chamber 32 and the lower chamber 33 through the orifices 23 and 24.

FIGS. 2 and 3 show only the structure of the shock absorber 1, but the shock absorbers 2, 3, and 4 provided for the other wheels also have the structure of the shock absorber 1 shown in FIG. And a second actuator 42, a third actuator 43, and a fourth actuator 44 similar to those shown in FIG.

FIG. 4 shows the shock absorbers 1, 2, 3,
4 is a graph showing damping force characteristics of No. 4 and D1 to D10.
Indicates the damping coefficients of the shock absorbers 1, 2, 3, and 4, respectively. In FIG. 4, the vertical axis represents the damping force generated by the shock absorbers 1, 2, 3, and 4, and the horizontal axis represents the damping force.
The difference between the over-spring displacement speed Xs and the unsprung displacement speed Xu,
That is, the relative displacement speed between the sprung and unsprung ( Xs-Xu
). As shown in FIG. 4, the damping force characteristics of the shock absorbers 1, 2, 3, and 4 are represented by a damping coefficient D1.
By selecting any one of D10 to D10, the configuration can be changed in ten steps. FIG.
In the equation, D1 indicates a damping coefficient that generates the softest damping force, and D10 indicates a damping coefficient that generates the hardest damping force. Here, the damping coefficient Dk
(K is a positive integer, 1 to 10) represents (10) of the nine circular holes 28 formed in the first orifice plate 29.
-I) circular holes 28 are formed in the second orifice plate 31;
Is selected when it is in communication with the long hole 30 formed in the hole. Therefore, the damping coefficient D1 is equal to the first
It is selected when all of the nine circular holes 28 of the orifice plate 29 are in communication with the long holes 30 of the second orifice plate 31, and the damping coefficient D 10 is selected for each of the nine circular holes 28 of the first orifice plate 29. Is not communicated with the long hole 30 of the second orifice plate 31.

FIG. 5 is a vibration model diagram of the vehicle suspension device according to the embodiment of the present invention, where ms is the sprung mass, mu is the unsprung mass, xs is the sprung displacement, xu is the unsprung displacement, and ks Is the spring constant of the coil spring 7, kt is the spring constant of the tire, Dk is the shock absorbers 1, 2, 2,
3, 4 damping coefficients.

FIG. 6 is a schematic perspective view of the stepping motor 27. The stepping motor 27 includes a cylindrical body 50, a cylindrical body 50, and the like.
The rotor 51, the stator 52 and the lid 53 housed therein
It is composed of FIG. 7 is a schematic plan view of the rotor 51 and the stator 52. Similar to a normal stepping motor, a plurality of rectangular teeth are formed on an outer peripheral portion of the rotor 51, and an inner peripheral portion of the stator 52 has Correspondingly, a plurality of rectangular teeth are formed.
A solenoid 54 is wound. The rotor 51 has 2
The stopper pins 55, 56 are formed on the lid 53, as shown in FIG.
Are formed in the circumferential direction at a position corresponding to. The groove 57 engages with a stopper pin 55 formed on the rotor 51 to control the movable range of the stepping motor 27, while the groove 58 is provided with a stopper pin 56
By engaging the stopper pins 55, 56 with the grooves 57, 58, it is possible to perform alignment so that the center of gravity of the rotor 51 coincides with the center of rotation when the cover 53 is put on. Is what you do. Therefore, the lid 53
The circumferential angle when viewing both ends of the grooves 57 and 58 from the center of
The groove 8 is larger than the groove 57, and the grooves 57 and 58 are formed so that the movable range of the step motor 28 is determined solely by the groove 57. In FIG. 8, when the rotor 51 rotates clockwise, the damping coefficient Dk becomes larger and the damping force characteristic becomes harder, while when rotated counterclockwise, the damping coefficient Dk becomes smaller and the damping force characteristic becomes smaller. It is becoming softer,
When the rectangular teeth of the rotor 51 are moved to positions facing the adjacent rectangular teeth of the stator 52, that is, when the step motor 27 rotates one step, the damping coefficient Dk changes by one. ing. Therefore, when the stopper pin 55 is located at the first reference position, which is the right end of the groove 57, the damping coefficient Dk becomes D10, and the shock absorber 1 generates the hardest damping force.
When the stopper pin 55 is located at the second reference position, which is the left end of the groove 57, the damping coefficient Dk becomes D1, and the shock absorber 1 generates the softest damping force.

FIG. 9 is a block diagram of the control system of the vehicle suspension system according to the embodiment of the present invention.

Referring to FIG. 9, the control unit 8 constituting the control system of the vehicle suspension system according to the embodiment of the present invention includes an arithmetic judging unit 80 and an allowable value setting unit 81.
And a threshold value setting means 82. The operation determination means 80 includes a first pressure sensor 61 and a second pressure sensor 6 provided in the shock absorbers 1, 2, 3, and 4, respectively.
2, the damping force Fsi of each of the shock absorbers 1, 2, 3, and 4 detected by the third pressure sensor 63 and the fourth pressure sensor 64
(Where i represents each wheel and i = 1, 2, 3, 4), the first acceleration sensor 11, the second acceleration sensor 12, the third acceleration sensor 13, and the fourth acceleration The detection signal of the vertical acceleration ai on the spring detected by the sensor 14, the sprung spring detected by the first vehicle height sensor 71, the second vehicle height sensor 72, the third vehicle height sensor 73, and the fourth vehicle height sensor 74 A detection signal of the lower relative displacement ( xs-xu ) and a detection signal of the vehicle speed V detected by the vehicle speed sensor 15 are input. Further, a detection signal of the vehicle speed V detected by the vehicle speed sensor 15 and an estimation signal of the estimated value μ of the road surface friction coefficient from the anti-braking system (ABS) 66 are input to the allowable value setting means 81. . Further, the threshold value setting means 82 receives the detection signal of the steering angle θ from the steering angle sensor 65 and the allowable value signal from the allowable value setting means 81, and calculates and determines the threshold signal from the threshold value setting means 82. It is output to the means 80. Then, the operation determining means 80 integrates the vertical acceleration ai on the spring detected by the first to fourth acceleration sensors 11 to 14 by a numerical integration method or the like to calculate the displacement speed Xsi (Σa
i), that is, the output signal from the input frequency detecting means 83 which is calculated so as to be used by converting it as the sprung absolute speed at the position of each of the shock absorbers 1 to 4 and which detects the frequency of the input applied to the vehicle body. The vibration frequency region is determined by comparing the gain of the sprung absolute velocity with respect to the vibration frequency of FIG.

The calculation judging means 80 calculates the acceleration ai in the vertical direction and the detection signal of the vehicle speed V based on the detection signal.
According to a map or a table stored in advance, a damping coefficient Dki for determining the damping force characteristics of the shock absorbers 1, 2, 3, 4 of each wheel is calculated, a control symbol is generated, and the first actuator 41, 2 actuator 42, 3rd actuator 43, 4th actuator 4
4 to control the damping force characteristics of the shock absorbers 1, 2, 3, and 4. Further, the allowable value setting means 81 is provided with a detection signal of the vehicle speed V detected by the vehicle speed sensor 15 and the steering angle sensor 6.
5 and the shock absorbers 1, 2, 3 for the left and right wheels and the front and rear wheels according to a map or a table stored in advance, based on the detected signal of the steering angle θ detected by the ECU 5 and the estimated signal μ of the road surface friction coefficient from the ABS 66. , 4 and outputs an allowable value signal to the threshold value setting means 82. Further, threshold setting means 8
2, shock absorbers 1, 2, 3 and 4 for the left and right wheels based on a detection signal of the steering angle θ detected by the steering angle sensor 65 in accordance with a map or a table stored in advance.
The threshold value for changing the change sensitivity of the damping coefficient Dki is set, and a threshold signal is output to the operation determining means 80.

Here, the damping force Fsi takes a continuous value, and has a positive value when acting upward on the sprung, that is, a positive value when the space between the sprung and the unsprung is contracted, and when acting downward, namely the spring. It is set to be a negative value when the distance between the upper part and the lower part is extended, and the acceleration ai
Is set to have a positive value when facing upward and a negative value when facing downward.

The operation determining means 80 includes a responsiveness detecting means 92 and a correcting means 91. The responsiveness detecting means 92 receives the first actuator 41, the second actuator 42, When the operations of the third actuator 43 and the fourth actuator 44 are slower than a predetermined operation response speed, an output signal is output to the correction means 91. In addition, the correction unit 91 responds to the output signal from the responsiveness detection unit 92,
To reduce the frequency of changing the damping force characteristics of 2, 3, and 4,
The control signals from the operation determination means 80 to the first actuator 41, the second actuator 42, the third actuator 43, and the fourth actuator 44 are respectively corrected.

FIG. 10 is a flowchart showing a routine of the damping coefficient selection control according to the running state, which is performed by the control unit 8 when the control mode is selected by the mode selection switch 16. In the routine of the coefficient selection control, the change of the damping coefficient Dki is performed too frequently, and as a result, the change control is performed in accordance with the running state in order to prevent a loud noise or vibration or a response delay from occurring when the change is made. The range of the obtained attenuation coefficient Dki is limited.

In FIG. 10, first, at step SA1,
The vehicle speed V detected by the vehicle speed sensor 15 is input, and the first acceleration sensor 11, the second acceleration sensor 12,
The vertical acceleration ai on the spring detected by the third acceleration sensor 13 and the fourth acceleration sensor 14 is input.

Next, at step SA2, the vehicle speed V
Is the first predetermined vehicle speed V1, which is a low speed value, for example, 3 km / h
Determines whether or not the on the following.

As a result, the vehicle speed V becomes equal to the first predetermined vehicle speed V1.
In the case of the following NO, the process proceeds to step SA3, where the vehicle speed V is extremely low, so that the damping force characteristics of the shock absorbers 1, 2, 3, and 4 become hard in order to prevent Scott and braking dives. Fix Dki to D8i.
Therefore, the damping coefficient Dki is because is fixed to D8i, change control of the damping force characteristic by attenuation coefficient selection control routine shown in FIG. 10 is not performed.

On the other hand, when the vehicle speed V exceeds the first predetermined vehicle speed V1 (YES), the routine proceeds to step SA4, in which the absolute value of the vertical acceleration ai on the spring exceeds the predetermined value ai0. It is determined whether it is medium.

As a result, the vertical acceleration ai on the spring
If it is determined that the vehicle is traveling on a bad road in which the absolute value of the vehicle speed exceeds the predetermined value ai0, the process proceeds to step SA5, and the vehicle speed V becomes the third speed.
It is determined whether or not the predetermined vehicle speed V3 is, for example, 50 km / h or more.

If it is determined in step SA5 that the vehicle speed V is equal to or higher than the third predetermined vehicle speed V3, the process proceeds to step SA6 in which the emphasis is placed on the improvement of the running stability and the damping force characteristic is relatively adjusted. In order to control the change within a hard range, the damping coefficient Dki is set in a range from D5i to D7i. As a result, in the Le <br/> routine of attenuation coefficient selection control shown in FIG. 10, the damping coefficient Dki is, D5i becomes the lower limit, even if satisfied even further conditions to be changed to the soft, damping coefficient Dki is held at D5i, while D7i is at the upper limit, and even if the condition to change more hardly holds, the damping coefficient Dki is held at D7i.

On the other hand, if the determination in step SA5 is NO, that is, if the vehicle speed V is lower than the predetermined vehicle speed V3, the process proceeds to step SA7, in which both running stability and riding comfort are improved. Since it is necessary , the damping coefficient Dki is set in the range of D3i to D7i so that the damping force characteristic can be changed and controlled within a range from a relatively soft state to a hard state. Accordingly, the damping coefficient selection control routine shown in FIG. 10, the damping coefficient D
ki is a condition in which D3i is at the lower limit, and even if the condition to be further changed to software is satisfied, the damping coefficient Dki is held at D3i, while D7i is at the upper limit, and the condition to be changed to harder is set. Holds, the damping coefficient Dki is held at D7i.

On the other hand, if the determination in step SA4 is NO, in which it is determined that the absolute value of the acceleration ai in the vertical direction on the sprung is equal to or less than the predetermined value ai0, the process proceeds to step SA8, in which a normal road is used instead of a rough road. Since it is considered that the vehicle is running, in this step SA8, the vehicle speed V further increases to the second predetermined vehicle speed V
2. For example, it is determined whether the speed is 30 km / h or less.

As a result, when it is determined that the vehicle speed V is in the low-speed running state equal to or lower than the second predetermined vehicle speed V2, YES is determined in step SA9. The damping coefficient Dki is set in the range of D1i to D3i so that the change control is performed within the range.
Accordingly, in Le chromatography <br/> Chin damping coefficient selection control shown in FIG. 10, the damping coefficient Dki is, when the D1i, the damping coefficient Dki even if they further conditions to be changed software is established D1i On the other hand, D3i becomes the upper limit value, and the damping coefficient Dki is held at D3i even if the condition to be changed more hardly holds.

On the other hand, if it is determined in step SA8 that the vehicle speed V is greater than the second predetermined vehicle speed V2, the flow proceeds to step SA10 in which the vehicle speed V is further increased.
Is less than or equal to a fourth predetermined vehicle speed V4, for example, 60 km / h.

As a result, when it is determined that the vehicle speed V is in the relatively middle speed running state equal to or lower than the fourth predetermined vehicle speed V4, the process proceeds to step SA11, where two requests are made to improve running stability and riding comfort. It is necessary to set the damping coefficient Dki in the range of D2i to D6i so that the damping force characteristic can be changed and controlled within a range from a relatively soft state to a hard state. I do. Accordingly, the damping coefficient selection control routine shown in FIG. 10, the damping coefficient Dki is D2i becomes the lower limit value, the damping coefficient Dki be conditions to be changed are satisfied soft than if retained in D2i, On the other hand, D6i becomes the upper limit value, and even if the condition to be changed more hardly holds, the damping coefficient Dki
Will be held at D6i.

On the other hand, if the determination in step SA10 determines that the vehicle speed V is greater than the fourth predetermined vehicle speed V4, the process proceeds to step SA12, where the vehicle speed V is further increased to the fifth predetermined vehicle speed V5, for example, It is determined whether the speed is 80 km / h or less.

As a result, when it is determined that the vehicle speed V is in the middle-speed running state equal to or lower than the fifth predetermined vehicle speed V5, the flow proceeds to step SA13 to improve the running stability and the riding comfort.
The damping coefficient Dki is set in a range from D4i to D6i in order to slightly change and control the damping force characteristics of the shock absorbers 1, 2, 3, and 4 while achieving both requirements. Accordingly, the routine of the damping coefficient selection control in FIG. 10, the damping coefficient Dki is D4i becomes the lower limit, even if conditions for further changes to the software is satisfied damping coefficient D
ki is held at D4i, while D6i becomes the upper limit value, and even if the conditions to be changed to harder are satisfied, the damping coefficient Dki is held at D6i.

On the other hand, when the vehicle speed V becomes equal to the fifth predetermined vehicle speed V5
When it is determined that the vehicle is in the high-speed running state exceeding the threshold value NO, the process proceeds to step SA14, and the damping coefficient Dki is adjusted so that the damping force characteristic is controlled to be changed within a hard range with emphasis on improving running stability. Set in the range of D7i to D10i. Accordingly, the routine of the damping coefficient selection control in FIG. 10, the damping coefficient Dki is D7i becomes the lower limit value, even further damping coefficient Dki be conditions to be changed are satisfied soft D
7i, while the damping coefficient Dki is held at D10i even if the conditions to be changed to harder are satisfied.

FIGS. 11 and 12 show the control of the change of the damping force characteristics of the shock absorbers 1, 2, 3, and 4 of the wheels executed by the control unit 8 when the control mode is selected by the mode selection switch 16. 9 is a flowchart illustrating a basic routine.

First, in step SB1 of FIG. 11, the detection signal of the vehicle speed V detected by the vehicle speed sensor 15, the detection signal of the steering angle θ detected by the steering angle sensor 65, and the estimation value μ of the road surface friction coefficient from the ABS 66 are estimated. Input each signal. Next, in step SB2, it is determined whether or not the vehicle speed V is equal to or lower than a fourth predetermined vehicle speed V4. If the determination is YES that the vehicle speed V is equal to or lower than the fourth predetermined vehicle speed V4, it is determined that the vehicle is in the low-speed running state. Therefore, even if the difference between the damping coefficients Dki of the shock absorbers of the left and right wheels 1, 2 or 3, 4 is large,
Since the steering characteristic does not change much and diagonal vibration does not matter, no allowable value signal is output. Therefore, the damping coefficient D of the shock absorbers 1, 2, 3, 4 of each wheel
ki is held as it was in the previous attenuation coefficient Dki, and no allowable value signal is output.

On the other hand, when the vehicle speed V is equal to the fourth predetermined vehicle speed V
When NO is equal to or greater than 4, it is determined that the vehicle is running at a medium speed or higher, and the process proceeds to Step SB3. If the difference between the damping coefficients Dki of the shock absorbers of the left and right wheels 1, 2, and 3, and 4 is large, steering is performed. Since the characteristics change and diagonal vibration occurs, it is further determined whether or not the vehicle speed V is equal to or less than a fifth predetermined vehicle speed V5 in order to determine what value the allowable value should be set. As a result, the vehicle speed V becomes the fourth predetermined vehicle speed V4
, But is equal to or lower than the fifth predetermined vehicle speed V5
In step SB4, it is determined whether the estimated value μ of the road surface friction coefficient is equal to or smaller than a predetermined value μ0.

As a result, when the vehicle is traveling on a road surface having a small road friction coefficient in which the estimated value μ of the road surface friction coefficient is smaller than the predetermined value μ0, the allowable value τ is set to the predetermined value τ0 in step SB5. On the other hand, if the vehicle is traveling on a road surface having a large road friction coefficient where the estimated value μ of the road surface friction coefficient exceeds the predetermined value μ0, the allowable value τ is set to a predetermined value τ1 larger than τ0 in step SB6. , And outputs an allowable value signal to step SB7 as the threshold value setting means 82.

On the other hand, if the determination in step SB3 is NO that exceeds the fifth predetermined vehicle speed V5, step SB8
Then, it is determined whether or not the estimated value μ of the road surface friction coefficient is equal to or smaller than a predetermined value μ0. As a result, when the vehicle is traveling on a road surface having a small road friction coefficient in which the estimated value μ of the road surface friction coefficient is less than the predetermined value μ0, the allowable value τ is set to the predetermined value τ1 in step SB9, while the road surface friction is set. When the vehicle is traveling on a road surface having a large coefficient of road friction in which the estimated value μ of the coefficient exceeds a predetermined value μ0, the allowable value τ is set to τ in step SB10.
The threshold value is set to a predetermined value .tau.2 larger than 1, and an allowable value signal is output to step SB7 (threshold setting means 82). In this case, the allowable value setting means 8 is determined by the above steps SB1 to SB6 and steps SB8 to SB10.
1 is configured.

When the allowable value signal is input from the allowable value setting means 81 in step SB7, the first
Based on the vertical acceleration ai on the spring input from the acceleration sensor 11, the second acceleration sensor 12, the third acceleration sensor 13, and the fourth acceleration sensor 14, a vertical motion component G is calculated according to the following equation. , And the roll component R are calculated.

G = (a1 + a2 + a3 + a4) / 4 R = (a1 + a3) / 2− (a2 + a4) / 2 ... Then, in step SB11, the steering angle sensor It is determined whether or not the absolute value | θ | of the steering angle θ inputted from 65 is in a substantially straight traveling state smaller than the predetermined steering angle θ0, and the absolute value | θ | of the steering angle θ is determined from the predetermined steering angle θ0. If YES in the small substantially straight-ahead state, it is determined in step SB12 whether or not | R / G | is larger than the allowable value τ.

On the other hand, when the determination in step SB11 is NO when the absolute value | θ | of the steering angle θ is larger than the predetermined steering angle θ0 (| θ | ≧ θ0), | R / G | Is larger than the allowable value τ, it cannot be determined that the damping force of the shock absorbers 1, 2, 3 and 4 of the left and right wheels is in a state of changing the steer characteristic and causing diagonal vibration. , Threshold α, β
Are set to αsi and βsi, respectively, and output to step SB14 as the operation determining means 80. In this case, if | R / G | is smaller than the allowable value τ in step SB12, the shock absorbers 1, 2, and 3
The threshold setting means 82 sets the thresholds α and β to αsi and βsi, respectively, since it is not recognized that the damping force of No. 4 is different enough to cause diagonal vibration by changing the steer characteristics. And outputs it to step SB14 (operation determination means 80) of FIG.

On the other hand, the determination in step SB12 is | R
If / G | is larger than the allowable value τ, it is determined in step SB15 whether or not R> 0. If YES, the damping of the shock absorbers 2, 4 for the right front wheel and the right rear wheel is determined in step SB16. The thresholds α2, β2 and α4, β4 for changing the change sensitivity of the force characteristic are αh2, βh2
And αh4, βh4, and output to step SB14. On the other hand, the determination in step SB15 is NO where R ≦ 0.
In step SB17, the thresholds α1, β1 and α3, β3 for changing the sensitivity of changing the damping force characteristics of the left front wheel and the left rear wheel shock absorbers 1, 3 are set to αh1, βh1, αh3, βh3, respectively. Is set and output to step SB14.

FIGS. 13 (a) and 13 (b) show the damping force, the sprung and unsprung relative displacement speeds ( Xs-Xu ) and the threshold values αi, β
i is a graph showing the relationship of i, and the threshold setting means 82 stores this graph in the form of a map.

13 (a) and 13 (b), Rh is a characteristic region where the damping force characteristic is changed to the hard side, that is, D (k) where the damping coefficient Dki is one larger than the previous damping coefficient Dki.
+1) i is the characteristic region where the damping force characteristic is changed to the soft side, that is, the damping coefficient Dki
Indicate characteristic regions that are changed to D (k -1 ) i which is one smaller than the previous attenuation coefficient Dki, respectively, and the threshold values αh1,
A region between βh1 and a region between thresholds αsi and βsi indicate a region where the damping force characteristic is not changed, that is, a dead zone region.

As is apparent from FIGS. 13A and 13B, the threshold values αhi and βhi shown in FIG.
Are set so that their inclinations are smaller than those of the threshold values αsi and βsi shown in FIG. 3, and as a result, the characteristic region Rs in which the damping force characteristic is changed to the soft side is the threshold value αi
When .alpha.hi and .beta.hi are selected as .alpha.hi and .beta.i, the characteristic region Rh is smaller than when .alpha.si and .beta.si are selected as thresholds .alpha.i and .beta.i, while the damping force characteristic is changed to the hard side. Are αhi and βhi as the thresholds αi and βi
Is selected as the thresholds αi, βi, αs
Therefore, when αhi and βhi are selected as the threshold values αi and βi, the damping force characteristic is hardly changed to the software side and changed to the hard side when i and βsi are selected as the threshold values αi and βi. Αhi,
βhi, αsi, and βsi are set. It should be noted that the threshold value setting means 82 normally outputs a threshold value signal with α = αsi, β = βsi to the arithmetic determination means 80.

Based on the threshold signal input from the threshold setting means 82, the operation judging means 80
In the same manner as 1, shock absorbers 1 for the left and front wheels,
The damping coefficient Dki of the shock absorbers 2 and 4 of the right and left front wheels is controlled.

In step SB14 of FIG. 12, when the threshold signal is input from the threshold setting means 82, the first acceleration sensor 11, the second acceleration sensor 12, the third acceleration sensor 13, and the fourth acceleration sensor The vertical acceleration ai on the spring detected by the sensor 14 and the first pressure sensor 6
1, the damping force Fsi detected by the second pressure sensor 62, the third pressure sensor 63, and the fourth pressure sensor 64 is input. Next, at step SB18, the vertical acceleration ai input at step SB14 is integrated to calculate the displacement speed Xsi (= Σai) on the spring.

Thereafter, in step SB19, the skyhook damping force Fai, which is an ideal damping force, is calculated by multiplying the displacement speed Xsi on the spring calculated in step SB18 by a predetermined constant K (K <0). . Then, step SB2
In step 0, hα is calculated according to the following equation: hα = Fsi (Fai−αFsi)..., And it is determined in step SB21 whether hα is positive.

If the result is YES, that is, if hα is positive, the routine proceeds to step SB22, in which the first actuators 41, 2, 3 of the shock absorbers 1, 2, 3, 4 whose hα is positive.
A control signal is output to the second actuator 42, the third actuator 43, and the fourth actuator 44 to rotate the stepping motor 27 clockwise in FIG. 8 by one step, so that the damping coefficient Dki is one more than the previous damping coefficient Dki. Large D (K +
1) While it is changed to i, that is, to make it harder, when hα is not positive NO, the process proceeds to step SB23, and further according to the formula, hβ = Fsi (Fai−βFsi) ··········· Calculates hβ, and determines in step SB24 whether hβ is negative.

As a result, if hβ is negative, that is, if YES, in step SB25, the first actuators 41, 2, 3, 4 of the shock absorbers 1, 2, 3, 4 whose hβ is negative are determined.
A control signal is output to the second actuator 42, the third actuator 43, and the fourth actuator 44, and the step motor 27 is rotated by one step in the counterclockwise direction in FIG. 8, so that the damping coefficient Dki is one more than the previous damping coefficient Dki. Small D (k-
1) Change to be i, that is, to be softer. On the other hand, when hβ is not negative and NO, in step SB26, the stepping motor 27 is not rotated, that is, the damping coefficient Dki is maintained without being changed from the previous damping coefficient Dki, and the next cycle is performed. Transition. In this case, the operation judging means 80 is executed by the above steps SB14 and SB18 to SB26.
Is configured.

Here, α and β are threshold values for preventing the change of the damping coefficient Dki from being performed too frequently, resulting in the occurrence of loud noise or vibration and the occurrence of a response delay at the time of the change. And usually, α> 1, 0 <β <1
Is set to

That is, when Fsi and Fai have the same sign,
Since (Fai−αFsi) in the equation is α> 1, compared to the case where Fsi is not multiplied by α, it tends to have a different sign from Fsi, and as a result, hα tends to be negative, and thus attenuation It is difficult to change the coefficient Dki, and furthermore, (F
ai−βFsi) is 0 <β <1, so that Fsi tends to have the same sign as Fsi as compared to the case where Fsi is not multiplied by β, and as a result, hβ tends to be positive. D
It becomes difficult to change ki.

On the other hand, when Fsi and Fai have different signs, it is impossible to match the actual damping force Fsi with the skyhook damping force Fai which is an ideal damping force.
It is desirable to make the damping coefficient Di close to zero, that is, to change the damping coefficient Di to be softer in order to make Fsi closer to Fai. Therefore, in this embodiment, when Fsi and Fai have different signs, both hα and hβ have negative values, and as a result, the control unit 8
As a result, the damping coefficient Dki is changed to D (k-1) i, which is one less than the previous damping coefficient Dki, that is, the damping coefficient Dki becomes softer, so that such a request can be satisfied.

The range of the damping coefficient Dki changed in the flowchart of FIG. 12 is limited by the routine of the damping coefficient selection control according to the running state of FIG. 10, and the step motor 27 is rotated one step clockwise in FIG. Then, the damping coefficient Dki is set to D (k + 1) i which is one larger than the previous damping coefficient Dki.
Even if it should be changed, the previous damping coefficient Dki is held as it is, and the stepping motor 27 is rotated one step counterclockwise in FIG.
Even if it is to be changed so as to be one or two smaller D (k-1) i, if the previous damping coefficient Dki is equal to the lower limit of the damping coefficient Dki selected in the routine of the damping coefficient selection control, damping is performed. The coefficient Dki is maintained as the previous attenuation coefficient Dki.

FIG. 14 is executed to reduce the frequency of changing the damping force characteristic of the shock absorber by the response detecting means 92 and the correcting means 91 of the control unit 8 when the control mode is selected by the mode selection switch 16. Shock absorbers 1 for each wheel
It is a flowchart which shows the routine of damping force characteristic change control of 2, 3, and 4.

First, the timer t is started (ON) in step SC1 of FIG. 14, and then in step SC2, the control symbol generated by the calculation judging means 80, that is, the damping coefficient of the shock absorbers 1, 2, 3, 4 Dki to D (k +
x) The signal to be changed to i is given by the first actuator 41 and the second
It is determined whether or not output has been made to the actuator 42, the third actuator 43, and the fourth actuator 44. In this case, the range in which the attenuation coefficient Dki is changed to D (k + x) i is as shown in FIG.
It is limited by the routine of the damping coefficient selection control according to the running state of 0, and the determination is executed only when the damping coefficient D (k + x) i is included in this range.

As a result, when the signal for changing the attenuation coefficient Dki to D (k + x) i is output as YES, the process proceeds to step SC3, while the signal for changing the attenuation coefficient Dki to D (k + x) i is obtained. Is not output, the first actuator 41,
It is determined that the second actuator 42, the third actuator 43, and the fourth actuator 44 are operating normally, and prepares for the determination of the next control signal. Then, in step SC3, the first actuator 41 and the second actuator 4
2, third actuator 43, fourth actuator 44
Of the shock absorbers 1 for each wheel
It is determined whether the damping coefficients Dki of 2, 3, and 4 have changed to D (k + x) i, and the damping coefficient Dki has not changed to D (k + x) i.
If the result is O, it is determined in step SC4 whether the timer has exceeded a first predetermined time t0. As a result, when the timer is NO when the first predetermined time t0 has not elapsed, it waits for the damping coefficient Dki to change to D (k + x) i until the first predetermined time t0 elapses. On the other hand, the timer is set to the first predetermined time t0.
If YES has elapsed, it is determined again in step SC5 whether or not the damping coefficient Dki of the shock absorbers 1, 2, 3, and 4 of each wheel has been changed to D (k + x) i. If Dki is not changed to D (k + x) i, NO in step SC6, it is determined whether the timer has passed a second predetermined time t1 longer than the first predetermined time t0.

As a result, when the timer is NO when the first predetermined time t1 has not elapsed, the damping coefficient Dki is not used until the second predetermined time t1 elapses after the first predetermined time t0 elapses.
Waits to change to D (k + x) i while the timer
If the predetermined time t1 has elapsed and the answer is YES, step SC7
In the above, it is determined that a failure such as disconnection has occurred between the control unit 8 and the first actuator 41, the second actuator 42, the third actuator 43, and the fourth actuator 44, and the process is terminated after fail determination.

On the other hand, when the determination in step SC5 is YES when the damping coefficient Dki of the shock absorbers 1, 2, 3, and 4 of each wheel is changed to D (k + x) i, that is, the first
When the damping coefficient Dki changes to D (k + x) i before the second predetermined time t1 elapses after the predetermined time t0 elapses,
In step SC8, according to the characteristic diagram showing the change characteristic of the gain of the sprung absolute speed with respect to the vibration frequency shown in FIG. 15 stored as a map in the correcting means, whether the gain Gav of the sprung absolute speed is larger than a predetermined value Gav0 is determined. Is determined. When the determination is NO in which the gain Gav of the sprung absolute speed is smaller than the predetermined value Gav0, the gain Gav of the sprung absolute speed becomes smaller than the sprung resonance point ω1 and the unsprung resonance point ω2. It is determined that the area is shifted to a certain high-frequency vibration area, and step SC9
To D (k +
x) Changes to i are prohibited. On the other hand, if the determination in step SC8 is YES, the gain Gav of the sprung absolute speed is larger than the predetermined value Gav0, the gain Gav of the sprung absolute speed is determined.
Is determined to be in the low-frequency vibration region near the sprung resonance point ω1 and the unsprung resonance point ω2, and proceeds to step SC10 to change the change range of the damping coefficient Dki of the shock absorbers 1, 2, 3, and 4 of each wheel. Correction is made so as to regulate to D5i to D10i. In this case, the regulation of the damping coefficient Dki within the range of D5i to D10i is performed in accordance with the range of the damping coefficient Dki limited by the routine of the damping coefficient selection control according to the running state of FIG. If the range of the damping coefficient Dki restricted accordingly is, for example, in the range of D1i to D3i, D5i to
The restriction within the range of D10i is not performed, and if it is within the range of D3i to D7i, the restriction within the range of D5i to D10i is D5i to D7i.
Is regulated within the range.

Next, step SC11 and step S11
In C12, shock absorbers 1, 2, 3,
The threshold α is set to α × 2 and the threshold β is set to β ÷ 2 so that the attenuation coefficient Dki of 4 is maintained long .

If the determination in step SC3 is YES when the damping coefficient Dki has been changed to D (k + x) i, that is, the first
The damping coefficient Dki is D (k +
x) i, the first actuator 41, the second actuator 42, the third actuator 43, the fourth
When it is determined that the actuator 44 is operating normally or returning to normal, it is reset in step SC13 to prepare for the determination of the next control signal.

Accordingly, the response detecting means 90 for detecting the operation response speed of the first actuator 41, the second actuator 42, the third actuator 43, and the fourth actuator 44 is constituted by the steps SC3 to SC6 of the above flow. I have. Also, by step SC8,
An input frequency detecting means 83 for detecting an input frequency applied to the vehicle body is provided.

Therefore, in the above embodiment, the shock absorber
First to change the damping coefficient Dki of the absorbers 1, 2, 3, 4
Actuator 41, second actuator 42, third
The actuator 43 and the fourth actuator 44 are
The operating signal from the roll unit 8, that is, the damping coefficient Dki
A signal for changing to D (k + x) i is output for a first predetermined time t0.
Until the second predetermined time t1 has elapsed.
When the decay coefficient Dki is changed to D (k + x) i, a decrease in responsiveness is detected.
The shock absorbers 1, 2, 3, and 4
Correction means 91 reduces the frequency of changing number Dki
The operation is performed based on the corrected operation signal of the control unit 8.
Moving between the soft side and the hard side at a very high speed
Actuators that are overheated when changed by41,4
2,43,44, the change frequency is determined by the correction means 90.
It is made to decrease by the correction.

In this case, the input frequency applied to the vehicle body is detected.
Output signal from the input frequency detection means
When the vibration frequency is lower than the vibration frequency of
Only actuator41,42,43,4Operation signal to 4
Signal from the input frequency detection means 83
Output signal is higher than the predetermined vibration frequency, that is, the spring
The high absolute speed gain Gav is smaller than a predetermined value Gav0.
Actuator when in frequency vibration range41,4
2,43,44 keeps the previous damping coefficient Dki
And shock absorbers 1, 2, 2,
Reduce the frequency of changing the damping coefficient Dki of 3, 4
It suppresses unpleasant low-frequency vibrations that are input. Also,
The gain Gav of the sprung absolute speed is larger than a predetermined value Gav0.
Shock absorber when the vibration range is low
The change range of the attenuation coefficient Dki of 1, 2, 3, 4 is set to D5i to D10.
i so that the shock absorber
The damping coefficient Dki of the sovers 1, 2, 3, 4 depends on the speed V
Harness to ensure maneuvering stability within the selected range
Actuator is further restricted to the range41, 4
2,43,44The frequency of changes in
Is secured. Furthermore, the gain Gav of the sprung absolute speed is
It is a low frequency vibration region larger than the predetermined value Gav0,
Maneuvering stability within the range selected according to the speed V
Ensure that the hard side is restricted to the range when shocked
The damping coefficient Dki of the absorbers 1, 2, 3, 4 isHeld longer
BeThe threshold α is α × 2 and the threshold β is β÷2
By setting each toActuator 41,
Reduce the frequency of change of 42, 43, 44 and input to vehicle body
Suppresses unpleasant low-frequency vibrations. As a result,
Actuator41,42,43,4Figure 4 shows the temperature drop
While the actuator41,42,43,4Step out of 4
Can be reliably prevented.

Note that the present invention is not limited to the above embodiment, but includes various other modifications.
For example, in the above embodiment, the sprung absolute speed gain Gav
Is a low frequency vibration region larger than the predetermined value Gav0,
In addition, the damping coefficient Dki of the shock absorbers 1, 2, 3, and 4 is kept long when it is restricted to the range on the hard side that ensures the steering stability within the range selected according to the speed V. Thus, the threshold α is α × 2, and the threshold β is β ÷
2 is set, but when the gain of the sprung absolute speed is in a high frequency vibration region smaller than a predetermined value, the operation signal to the actuator is maintained at the previous damping coefficient and the damping coefficient of the shock absorber is changed. While reducing the frequency, the control for changing the damping coefficient of the shock absorber may be performed normally when the gain of the sprung absolute speed is in a low-frequency vibration region larger than a predetermined value.
Further, when the gain of the sprung absolute speed is in a low-frequency vibration region larger than a predetermined value, the change range of the damping coefficient of the shock absorber may be corrected so as to be restricted to D5i to D10i.

In the above embodiment, the road surface friction coefficient μ
Is estimated based on the detection signal of the ABS 66,
The road surface friction coefficient μ may be estimated based on the signal of the wiper, and it is determined whether or not the road is a bad road based on the amount of change in the vertical acceleration ai within a predetermined time. A bad road determination may be made by another method.

In the above-described embodiment, the stepping motor 2 is driven in the running state in which it is determined that the ride comfort should be emphasized.
7 is rotated in two stages, and the damping coefficient Dki is
Although the value is changed to D (k-2) i, which is two times smaller than ki, the step motor 27 may be rotated three or more steps.

[0087] In the above embodiment, to form the two stopper pins 55, 56 to the rotor 51 of the scan Teppumota 27, scan the grooves 57, 58 for engagement therewith Teppumota 27
Although the forms on the lid 53, is formed in two Sutoppapi Ngasu Te <br/> Ppumo data of the lid, it is formed on Mizogasu Te'<br/> Pumo data row data to be engaged therewith may be in so that, furthermore, the two Sutoppapi emissions of one gas Teppumo other Russia <br/> over data, respectively is formed on the other gas Teppumo data of the lid
Is, for one engages in Sutoppapi emissions formed in the rotor
The lid of Mizogasu Teppumo data, Mizogasu Teppumo to other Sutoppapi emissions engage formed in the lid of the step motor
It may be respectively formed data row data.

Further, in the above embodiment, the step motor 27 is used as an actuator for changing the damping force of the shock absorbers 1, 2, 3, 4 and the damping force of the shock absorbers 1, 2, 3, 4 is controlled by open control. Although it has to, using a DC motor instead of the step motor 27 may be controlled <br/> damping force of the shock absorber by a feedback control.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a component layout of a suspension device.

FIG. 2 is a vertical sectional front view showing a main part of the shock absorber.

FIG. 3 is an exploded perspective view of the actuator.

FIG. 4 is a graph showing a damping coefficient of a shock absorber.

FIG. 5 is a schematic diagram showing a vibration model of the suspension device.

FIG. 6 is a perspective view of a step motor.

FIG. 7 is a plan view of a rotor and a stator.

FIG. 8 is a bottom view of the lid.

FIG. 9 is a block configuration diagram of a control unit of the suspension device.

FIG. 10 is a flowchart illustrating a routine of damping coefficient selection control according to an operation state.

FIG. 11 is a flowchart illustrating a first half of a basic routine of damping force characteristic change control of each shock absorber executed by the control unit.

FIG. 12 is a flowchart showing the latter half of the basic routine of damping force characteristic change control of each shock absorber executed by the control unit.

FIG. 13 is a characteristic diagram showing a relationship between damping force, relative speed between sprung and unsprung portions, and threshold values α and β.

FIG. 14 is a flowchart showing a routine of a damping force characteristic change control of each shock absorber executed by the correction means.

FIG. 15 is a characteristic diagram showing a change characteristic of a gain of a sprung absolute speed with respect to a vibration frequency.

[Explanation of symbols]

 1, 2, 3, 4 Shock absorbers 6, 7 Wheels 8 Control unit (control means) 9 Body 41, 42, 43, 44 Actuator 83 Input frequency detecting means 91 Correcting means 92 Responsiveness detecting means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (4)

(57) [Claims] 1. A shock absorber is provided between a sprung portion and a unsprung portion of each wheel, and a damping force characteristic of the shock absorber is changed according to a relative relationship between a displacement speed on the spring and a displacement speed on the unsprung portion. An actuator for changing a damping force characteristic of the shock absorber, a control means for outputting a control signal to the actuator to operate the actuator, and a response for detecting an operation response speed of the actuator. Detecting means for receiving a signal from the response detecting means, and controlling the control means to the actuator so as to reduce the frequency of changing the damping force characteristic of the shock absorber when the signal is slower than a predetermined operation response speed. A suspension device for a vehicle, comprising: correction means for correcting a signal. 2. The correction means receives an output signal from the input frequency detection means for detecting an input frequency applied to the vehicle body, and receives the output signal from the input frequency detection means. 2. The vehicle suspension apparatus according to claim 1, wherein the control signal to the actuator is corrected only when the signal is in a low frequency vibration region lower than a predetermined vibration frequency. 3. The control means controls the control means to control the actuator so as to regulate the range of change of the damping force characteristic of the shock absorber by the actuator when the signal from the response detection means is slower than a predetermined operation response speed. The vehicle suspension device according to claim 1, wherein the signal is corrected. 4. The correction means corrects the control signal of the control means to the actuator so that the damping force characteristic of the shock absorber is maintained long when the signal from the response detection means is lower than a predetermined operation response speed. The vehicle suspension device according to claim 1, wherein