JPH0316285B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention improves the riding comfort of a vehicle by adjusting the transmission force transmitted to the vehicle body via the shock absorber by controlling the damping force of the shock absorber. The present invention also relates to a shock absorber control device that can improve vibration damping effects.

[Prior art]

As a conventional shock absorber control device,
For example, there is one disclosed in Japanese Patent Application Laid-Open No. 58-30542. The shock absorber control device includes a variable orifice that is incorporated into a hydraulic shock absorber and whose flow cross-sectional area can be adjusted to change the damping force of the shock absorber, and a variable orifice that can adjust the flow cross-sectional area of the variable orifice to change the damping force of the shock absorber. A solenoid built into the shock absorber, a vehicle height sensor that electrically detects the vehicle height value, and an excitation current supplied to the solenoid based on the detection signal of the vehicle height sensor to control the flow cross-sectional area of the variable orifice. The vehicle is characterized by a control circuit that increases the damping force of the shock absorber under predetermined vehicle height conditions, thereby controlling the damping force of the shock absorber according to the driving conditions and improving riding comfort. I try to let them do it.

[Problems to be Solved by the Invention] The conventional shock absorber control device described above is configured to control the damping force of the shock absorber in two levels, high and low, depending on the driving conditions, regardless of the unevenness of the road surface. As a result, the excitation force transmitted to the car body due to the uneven road surface cannot be properly damped, and the shaking of the car body causes phenomena such as rolling, pitching, and rolling back of the car body, reducing ride comfort. The problem was that it could not be improved. In other words, when the shock absorber is controlled to a low damping force, even small vibrations due to the smoothness of the road surface cannot be damped completely, and
If the shock absorber is controlled to a high damping force on a neutral, rough road with some undulations, the damping force will become unnecessarily high, and if the damping force is controlled to a high damping force, the vehicle body will shake, which in any case will reduce the ride comfort. The problem was that it caused deterioration.

[Means for solving problems]

The present invention has been made by focusing on these conventional problems, and as shown in the basic configuration diagram of FIG. , a variable damping force shock absorber whose damping force can be changed by inputting a control signal, and the amount of relative displacement between the sprung and unsprung portions of a vehicle connected by this variable damping force shock absorber, or the force transmitted to the vehicle body. displacement amount or transmission force detection means that outputs a detection signal according to the
a direction determination means for determining the direction of the relative displacement or transmission force detected by the detection means; and a neutral region for setting a neutral region of a predetermined width above and below a neutral position of the relative displacement of the shock absorber due to the relative displacement or transmission force. a setting means, and outputting the control signal for decreasing the damping force when the shock absorber is displaced in a direction away from the neutral position and increasing the damping force when the shock absorber is displaced in a direction approaching the neutral position. a control means, when there is a relative displacement between the variable damping force shock absorber within the neutral region, switching the damping force of the variable damping force shock absorber according to a driving condition based on a detection signal of the driving condition detector; It is an object of the present invention to solve the above problems by configuring a shock absorber control device including a correction means for controlling the output of the control means.

[Effect]

Therefore, the present invention detects the amount of relative displacement between the sprung portion and the unsprung portion of the vehicle based on the transmission force transmitted to the vehicle body by a displacement amount detection means, or detects the transmission force to the vehicle body by the transmission force detection means. Then, the detection signal is supplied to the direction determination means, which determines the direction of relative displacement of the variable damping force shock absorber. Based on the determination result, the control means controls the damping force of the variable damping force shock absorber. When the relative displacement is moving away from the neutral position, it is set low, and when the relative displacement is moving towards the neutral position, it is set high. When there is a relative displacement, the damping force of the shock absorber is changed according to the driving condition based on the detection signal of a driving condition detector such as a vehicle speed detector, so that the transmitted force that causes a change in the posture of the vehicle body can be adjusted according to the driving condition. By suppressing this, it is possible to improve the control effect of the vehicle body and to improve the ride comfort of the vehicle.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 2 to FIG. 9 are diagrams showing an embodiment of the present invention.

First, to explain the configuration, 1 shown in FIG.
This is a vehicle speed detector that outputs a detection signal according to the vehicle speed of the vehicle, and this vehicle speed detector 1 constitutes an example of a driving state detector that outputs a detection signal according to the driving state of the vehicle. Further, 2a to 2d are displacement detection means for detecting the relative displacement between the sprung and unsprung portions of the vehicle, 3 is a control device, and 4a to 4d are electromagnetic solenoids of variable damping force shock absorbers 6a to 6d, which will be described later. It is.

As shown in FIG. 3, the displacement detection means 2a to 2d are variable damping force shock absorbers 6a mounted between each wheel 5a to 5d of the vehicle and the vehicle body.
~6d, respectively.

Each variable damping force shock absorber 6a to 6d
As shown in FIG. 4, a piston 9 attached to the lower end of a piston rod 8 and a free piston 10 are slidably disposed in a cylinder tube 7. Therefore, the inside of the cylinder tube 7 is defined into three fluid chambers A, B and C. and,
The two fluid chambers A and B are filled with a working fluid such as hydraulic oil, and the other fluid chamber C is filled with high pressure gas.

The piston 9 has a central opening 12 whose upper end communicates with the fluid chamber A via a fluid passage 11 formed in the piston rod 8, and a central opening 12 which communicates with this and has a fluid chamber B.
A fluid passage 13 is bored in the center opening 12, and two fluid passages 11 and 1 are formed in the central opening 12.
A cylindrical spool 15 provided with a through hole 14 that communicates with the spool 3 is slidably disposed.

This spool 15 is normally urged downward by a return spring 16, and its lower end surface contacts a plunger 17, and the lower end of this plunger 17 contacts the bottom surface of the case 18 to restrict its movement. There is. In this state, the through hole 14 and the fluid passage 13
The opening ends of the two fluid passages 11 and 13 are located at a discrepancy with each other and do not face each other, so there is no communication between the two fluid passages 11 and 13, and the damping force is high as shown by the curve shown by the solid line _lH in FIG. Damping force is set.

Further, the plunger 17 is energized by applying excitation currents Ia to Id to the electromagnetic solenoids 4a to 4d disposed around the plunger by the control device 3 via the lead wire 19. Moved upward in proportion to the value of Id. As a result, the spool 15 is displaced upward against the return spring 16, and the opening area between the fluid passages 11 and 13 by the through hole 14 is increased, and the damping force is increased as indicated by the dashed-dotted line _lL in FIG. The damping force state is changed to a low damping force state as shown by the illustrated curve.

A cylindrical cover 20 whose lower end reaches the cylinder tube 7 and covers it is integrally attached to the upper end of the piston rod 8.
A cover 20 is provided on the inner peripheral surface of the cylinder tube 7 and the piston rod 8 to measure the relative displacement between the sprung portion and the unsprung portion of the vehicle.
A displacement detection coil 21 is wound around the cylinder tube 7 to detect a change in inductance due to a change in the amount of overlap between the cylinder tube 7 and the cylinder tube 7.

As shown in FIG. 6, the displacement detection coil 21 is incorporated into the LC oscillator 22 as a coil that determines the oscillation frequency of the LC oscillator 22.
From, cylinder tube 7 and piston rod 8
An oscillation output with a frequency corresponding to the amount of relative displacement is output. The oscillation output is the frequency-voltage conversion circuit 23
From this, displacement detection signals Sa to Sd having voltages corresponding to the relative displacements of the cylinder tube 7 and piston rod 8 as shown in FIG. 7 are output. These displacement detection coils 21,
The LC oscillator 22 and the frequency-voltage conversion circuit 23 constitute displacement amount detection means 2a to 2d.

As shown in FIG. 2, the control device 3 includes a microcomputer 30 having input/output ports, a processing unit (CPU), storage devices such as RAM, ROM, etc., and the vehicle speed detector is connected to the input port of the microcomputer 30. The vehicle speed detection signal DV of 1 is directly supplied, and the displacement detection signal Sa of each displacement detection means 2a to 2d is directly supplied.
~Sd is multiplexer 32 and A/D converter 3
3. Furthermore, the microcomputer 30 receives control signals CSa to CSd of logic value "0" or logic value "1" output from the output side port.
is output to drive transistors 34a-34d inserted in series with electromagnetic solenoids 4a-4d of variable damping force shock absorbers 6a-6d connected to a DC power source (not shown).

Then, the microcomputer 30
For example, 20 msec as shown in FIG.
Arithmetic processing is executed according to the timer interrupt processing program that is executed every time.

That is, in a step, the vehicle speed detection signal DV is read, and, for example, the number of pulses per unit time is measured to calculate the vehicle speed, and this is temporarily stored as the vehicle speed detection value V in the RAM of the storage device.

Next, the process moves to step and it is determined whether or not the vehicle is stopped. The determination in this case is made by reading out the vehicle speed detection value V stored in the above step and determining whether or not V≈0. Here, when the vehicle is stopped, the process moves to step and the control signals CSa to CSd of logical value "0" for controlling all variable damping force shock absorbers 6a to 6d to high damping force are applied to the drive transistors 34a to 34a to CSd. After outputting step 34d, the program returns to the main program, and if the vehicle is running, the process moves to the damping force control process from step 34d onward.

In the damping force control process, first, in step, the detection signal Sa of each displacement amount detection means 2a to 2d is
~Sd is read and these are converted into displacement detection values Xi (i=
A, b, c, and d) are temporarily stored in a predetermined storage area of the storage device. Next, the process moves to step and calculates the amount of displacement per unit time, which is the differential value of the detected displacement value Xi, that is, the amount of change X〓i (i=a,
b, c and d).

Next, the process moves to step 1, where the vehicle speed detection value V is read out and the vehicle speed detection value V is stored in advance in the storage device.
It is compared with a predetermined reference vehicle speed value K stored in the RAM (or ROM), and if the detected vehicle speed value V is less than the reference vehicle speed value K, the process moves to the low-speed driving control process after step, and the detected vehicle speed value V If the vehicle speed is greater than or equal to the reference vehicle speed value K, the process proceeds to the high-speed travel control processing from step onward.

In the low-speed running control process, first, in step, each variable damping force shock absorber 6i (i=
In a, b, c, and d), the amount of displacement Xn at the neutral position, which is the boundary position between the extension side and the contraction side, is
Add a predetermined neutral area setting amount δ set on the extension side from the neutral position, and the added value (X _N + δ) is
A difference value _D1 is calculated by subtracting it from the detected displacement value Xi stored in the step above, and it is determined whether the difference value _D1 is positive or negative. In this case, the judgment is
This is to determine whether the relative displacement between the cylinder tube 7 and the piston rod 8 is at a position other than the neutral region (X _N ~ +δ) on the extension side of the shock absorber 6i, and the detected displacement value Xi is In a state where D 1 is not in the extension side region other than the side neutral region and D ₁ >0, the process moves to the step.

In the step, contrary to the determination in the step, a predetermined neutral region setting amount δ set from the neutral position to the contraction side is subtracted from the neutral position displacement amount Xn of the variable damping force shock absorber 6i.
The subtracted value (X _N - δ) is subtracted from the detected displacement value Xi stored in the previous step to calculate the difference value _D2 , and it is determined whether the difference value _D2 is negative or positive. . In this case, the judgment is that the cylinder tube 7
The relative displacement between the shock absorber 6i and the piston rod 8 is the contraction side neutral region ( _X
This is to judge whether or not the detected relative displacement value Xi is in the contraction side area excluding the contraction side neutral area, and in a state where D ₂ < 0 is not established, the process moves to step .

In this step, a control signal CSi (i=a, b, c, and d) with a logical value of "1" for controlling each variable damping force shock absorber 6i to a low damping force is output to the drive transistor 34i, and the control signal CSi (i=a, b, c, and d) is divided by this. Finish the loading process and return to the main program.

In this way, when the detected relative displacement value Xi of each variable damping force shock absorber 6i is in the neutral region (+δ to -δ) between the set amount of the neutral region on the extension side to the set amount of the neutral region on the contraction side, each damping force variable shock absorber 6i To lower the damping force of the variable force shock absorber 6i.

Also, when the judgment result of the step is D ₁ > 0, the process moves to the step, reads the amount of change X〓i stored in the step, and determines whether the value is positive (including 0) or negative. Determine. In this case, the determination is made to determine whether the change in relative displacement X〓i of the shock absorber 6i is a displacement away from the neutral position or a displacement toward the neutral position. If the judgment result is that ,
If X≧i≧0, the process proceeds to step, and a control signal CSi of logical value “0” for controlling the variable damping force shock absorber 6i to a high damping force is output to the drive transistor 34i. Thereafter, each interrupt process is completed and the program returns to the main program.

Furthermore, when the judgment result of the step is D ₂ <0, the process moves to the step, reads the amount of change X〓i stored in the step, and determines whether the value is negative (including 0) or positive. Determine.
In this case, as in the case of the step above, it is determined whether the amount of change X〓i of the shock absorber 6i is a displacement away from the neutral position or a displacement toward the neutral position. The determination result is X〓i
When ≦0, the process proceeds to step, and a control signal CSi with a logical value of “1” for controlling the variable damping force shock absorber 6i to a low damping force is output to the drive transistor 34i, and if X〓i≦0 is not Sometimes, the control signal CSi of logic value "0" is transferred to the drive transistor 34i to control the variable damping force shock absorber 6i to a high damping force.
Output to. Thereafter, each interrupt process is completed and the program returns to the main program.

On the other hand, if the determination result of the step is V≧K and the vehicle is in a high-speed running state equal to or higher than a predetermined reference vehicle speed value K, the routine shifts to high-speed running control processing.

In the high-speed running control process, first, in a step similar to the step described above, the detected value Xi of the relative displacement stored in the step is read, and a value obtained by adding the neutral position displacement amount X _N and the extension side neutral region setting amount δ is read. A difference value D ₁ is calculated by subtracting (X _N +δ) from the displacement amount detection value Xi, and it is determined whether or not the difference value D ₁ is positive. If the determination result in step is not D ₁ >0, the process moves to step.

In this step, similarly to the previous step, the detected displacement value Xi stored in the previous step is read, and the value (X _N - δ) obtained by subtracting the contraction side neutral region setting amount δ from the neutral position displacement amount X _N is A difference value D ₂ is calculated by subtracting from the detected amount value X〓i, and it is determined whether or not the difference value D ₂ is negative. Then, when the step judgment result is not D ₂ <0,
The relative displacement between the cylinder tube 7 and the piston rod 8 is either the extension side neutral area (X _N + δ) or the contraction side neutral area (X _N -
δ), and in this case,
It is determined that the detected displacement value Xi is within a neutral region (+δ to -δ) of a predetermined width provided above and below the neutral position, and the process proceeds to step.

In this step, do the same as above,
A control signal CSi with a logic value of "0" for controlling the variable damping force shock absorber 6i to a high damping force is output to the drive transistor 34i, thereby ending the interrupt processing and returning to the main program.

Furthermore, when the judgment result of the step is D ₁ > 0, the process moves to the step, reads the amount of change X〓i stored in the step as described above, and checks if the value is positive (including 0). Determine whether or not. Then, the step judgment result is X〓i≧
The detected displacement value of the shock absorber 6i is 0.
When Xi is displaced in the direction away from the neutral position, the process moves to step and the logic value "1" is set to control the variable damping force shock absorber 6i to a low damping force.
control signal CSi is output to the drive transistor 34i, and the displacement amount detection value Xi which is not
When the variable damping force shock absorber 6i is displaced toward the neutral position, the control signal CSi of logical value "0" for controlling the variable damping force shock absorber 6i to a high damping force is outputted to the drive transistor 34i. Thereafter, each interrupt process is completed and the program returns to the main program.

Furthermore, the determination result of the step is D ₂ <0
If this is the case, the process moves to the step, and as described above, the amount of change X〓i stored in the step is read, and it is determined whether or not the value is negative (including 0). Then, the step judgment result is
When the detected displacement value Xi of the shock absorber 6i, where “Drives the control signal CSi of the transistor 34i
Also, when the detected displacement value Xi, which is not X〓i≧0, is displaced in a direction approaching the neutral position, the logic goes to step and controls the variable damping force shock absorber 6i to a high damping force. A control signal CSi of value "0" is output to the drive transistor 34i. Thereafter, each interrupt process is completed and the program returns to the main program.

Here, the step processing constitutes a correction means, the step, step, step and step processing constitutes a neutral region setting means, the step and step processing constitutes a control means, and the step and step processing constitute a control means. constitutes a direction determining means.

Next, the effect will be explained.

Assume that the vehicle is currently in a parked or stopped state where the vehicle has stopped running, and when the interrupt process shown in FIG. The signal DV is read and the detected vehicle speed value V is calculated based on this. At this time, since the vehicle is stopped, V=0,
It is determined that the vehicle is stopped at the step, and then
Shifting to step, a control signal CSi of logical value "0" for controlling all variable damping force shock absorbers 6i (i=a, b, c, and d) to high damping force is output to each drive transistor 34i.

In this way, when the control signal CSi with the logical value "0" is supplied to each drive transistor 34i, these drive transistors 34i are turned off, and the electromagnetic solenoid 4 of each variable damping force shock absorber 6i is turned off.
The supply of excitation current to i is cut off,
Each electromagnetic solenoid 4i is maintained in a non-energized state.

This causes the spool 15 to move to the return spring 1.
6, the through hole 14 and the fluid passage 13 are held in a conflicting position, and the two fluid passages 11 and 13 are cut off. Therefore, the flow resistance between the two fluid chambers A and B increases, and the damping force of each variable damping force shock absorber 6i is increased. Therefore,
When the vehicle is stopped, it is possible to maintain a stable vehicle body posture by preventing the vehicle body from being tilted due to passengers getting in and out of the vehicle or loading and unloading cargo.

This stop control state from step to step continues until the vehicle starts running.

Next, when the vehicle starts running, the pulse interval of the vehicle speed detection signal DV from the vehicle speed detector 1 becomes shorter in accordance with the vehicle speed, so the vehicle detection value V calculated in step becomes V≠0. Therefore, moving from step to step, each detection signal Si of each displacement amount detection means 2i representing the amount of relative displacement between the cylinder tube 7 and piston rod 8 of each variable damping force shock absorber 6i is read, and these are used to calculate the relative displacement. After storing the detected displacement value Xi in a predetermined area of the storage device, proceed to step
A differential value X〓i of the detected displacement value Xi is calculated and temporarily stored in a predetermined storage area.

Next, the process moves to step and compares the detected vehicle speed value V calculated in the step with the reference vehicle speed value K to determine whether the vehicle is in a predetermined low-speed running state (for example, less than 40 km/h). Determine whether the vehicle is running at high speed.

Here, when the vehicle is running at a low speed lower than the reference vehicle speed value K, it is determined in step that the vehicle is in a low-speed running state, so the low-speed running control process (the first one shown in FIG. 9b) control mode).

That is, by processing the steps, the detected displacement value Xi of the current relative displacement between the cylinder tube 7 and the piston rod 8 is adjusted to a neutral area (+δ~
−δ), or in the extension side area set above the neutral area (excluding the extension side neutral area), or in the contraction side area set below the neutral area (excluding the contraction side neutral area). Determine if there is.

Thus, when the relative displacement is in the extension side region, the step processing causes the relative displacement to move away from the neutral position, or to move toward the neutral position, depending on the step processing when the relative displacement is in the contraction side region. Based on the determination result, in the former case, the damping force of the variable damping force shock absorber 6i is lowered, while in the latter case, the damping force is increased. When the detected displacement value Xi is within the neutral region, the variable damping force shock absorber 6i is controlled to a low damping force regardless of the direction of relative displacement.

At this time, when one wheel (for example, 5a) of the vehicle passes through unevenness on the road surface, the cylinder tube 7 of the variable damping force shock absorber 6a is moved by the amount of relative displacement shown by the curve L in FIG. 9a.
When the detected displacement value Xa exceeds the set amount δ of the neutral region on the extension side at time t1 and shifts to the extension region, D ₁ >0 is determined in step. Because it is judged,
Move to step and change amount per unit time
Determine whether X〓a is greater than or equal to 0.

As a result, until time t2, when X〓a=0,
Since the detected relative displacement value Xa is increasing in the direction away from the neutral position displacement amount _XN ,
Since it is determined that Output.

In this way, when the control signal CSi with the logical value "1" is supplied to each drive transistor 34i, these drive transistors 34i are turned on, and the electromagnetic solenoid 4 of each variable damping force shock absorber 6i is turned on.
Excitation current Ii is applied to i. Therefore, since each electromagnetic solenoid 4i is energized, the plunger 1
7 is raised, the spool 14 is raised against the return spring 16, the opening area between the through hole 14 and the fluid passage 13 is increased, and the flow resistance between the fluid passages 11 and 13 is reduced. Fluid chambers A and B
The working fluid can easily flow between the two, and the damping force of the variable damping force shock absorber 6i is reduced. As a result, the riding comfort during normal driving can be improved, and the transmission force transmitted to the vehicle body in the excitation direction can be suppressed.

Thereafter, the interrupt process is ended and the main program is returned to, and this excitation force control state is repeated every time the interrupt process is executed, and continues until the excitation force is no longer applied.

When the detected displacement value Xa between the cylinder tube 7 and the piston rod 8 moves toward the neutral position displacement X _N side from this vibration control state, the amount of change X 0, so we move from step to step and move to the 9th step.
As shown in Figure b, a control signal with a logical value of "0" increases the damping force of the variable damping force shock absorber 6a.
Output CSa. As a result, the damping force of the variable damping force shock absorber 6a is increased in the same manner as described above.

After that, at time t3, when the detected relative displacement value Xa exceeds the neutral displacement amount δ on the extension side and moves to the neutral region, the transition occurs from step to step, and the detected displacement value Xa at that time is Xa<0. Determine whether it exists or not. At the time t3 when the transition to this neutral region occurs, Xa≧0, so the transition to step
As shown in the figure, a control signal CSa of logic value "1" for controlling the damping force of the variable damping force shock absorber 6a to a low damping force is applied to the drive transistor 34a.
Output to.

As a result, the variable damping force shock absorber 6
Since the damping force of a is reduced, the transmission force in the excitation direction transmitted to the vehicle body is suppressed, and a change in the posture of the vehicle body can be prevented. This low damping force state starts from the neutral area setting amount _δ before the neutral position displacement amount Moreover, it can be performed stably, and changes in the attitude of the vehicle body can be effectively suppressed.

Further, at time t4, when the detected displacement value Xa passes through the neutral region, exceeds the contraction side neutral region setting amount δ to the lower side, and moves to the contraction side region, D ₂
Since it is judged as <0, move to step
Determine whether the amount of change in relative displacement X〓a is X〓a≦0, and since X〓a≦0 until time t5,
Shifting from step to step, the control signal CSa of logic value "1" which causes the variable damping force shock absorber 6a to have a low damping force is continuously outputted to the drive transistor 34a.

Thereafter, at time t5, the amount of change in relative displacement Output to transistor 34a. Therefore, the damping force of the variable damping force shock absorber 6a is increased,
This provides a great damping effect and prevents changes in the vehicle's attitude.

This high damping force state continues until time t6, and
When t6 is reached and the amount of change in relative displacement X〓a exceeds the contraction side neutral region setting amount δ and enters the neutral region,
Since D ₁ ≦0 is determined in the step, and D ₂ ≧0 is subsequently determined in the step, the process moves to the step and the logic value "1" is set to set the variable damping force shock absorber 6a to a low damping force. Control signal
CSa is output to the drive transistor 34a. Therefore, the damping force of the variable damping force shock absorber 6a is reduced again, and the transmission force in the excitation direction transmitted to the vehicle body is suppressed, thereby preventing a change in the posture of the vehicle body.

Thereafter, at time t7, similarly to time t1, the control signal CSa of logic value "1" for controlling the variable damping force shock absorber 6a to a low damping force is continuously outputted to the drive transistor 34a.

Similar damping force variable shock absorber 6a
By repeating this control, changes in the posture of the vehicle can be suppressed and ride comfort can be improved.

Next, when the vehicle shifts to a high-speed running state and the vehicle speed increases to or above the reference vehicle speed value K, it is determined in step that the vehicle is in a high-speed running state.
The process moves to the high-speed running control process (second control mode shown in FIG. 9c) following the step.

At this time, similar to the low-speed running state described above, a relative displacement amount of the shape shown by the curve L in FIG. 9a is input to one wheel (for example, 5a) of the vehicle, and the detected relative displacement value Xa is When passing through the neutral region and exceeding the extension side neutral region setting amount δ to the higher side, check whether the detected displacement value Xa is in the extension side region excluding the extension side neutral region (X _N ~ δ) at step. Determine. At time t1 when the transition to this growth side region occurs,
Since D ₁ > 0, we move to the step and calculate the amount of change that is the differential value of the detected displacement value Xa at that time.
It is determined whether the value of X〓a is X〓a≧0 or not, and since Xa≧0 at this time, the process moves to step ``, which is a logical value for controlling the variable damping force shock absorber 6a to a low damping force. A control signal CSa of 1'' is output to the drive transistor 34a. Therefore, the damping force of variable damping force shock absorber 6a is reduced,
The transmission force transmitted to the vehicle body in the excitation direction is suppressed, and a change in the posture of the vehicle body is prevented.

Next, when time t2 is exceeded, the detected displacement value Xa
is displaced in the direction approaching the neutral position displacement amount X _N , so in step it is determined that The control signal CSa of logical value “0” to be controlled is transmitted to the drive transistor 34.
Output to a.

Thereafter, at time t3, it is determined in step that D ₁ ≦0, and then in step it is determined that D ₂ ≧0. Transistor 3 drives the control signal CSa of value “0”
Output to 4a. Therefore, the damping force of the variable damping force shock absorber 6a is continuously increased from time t2 to time t4, thereby exerting a damping effect and preventing changes in the attitude of the vehicle.

Next, after time t4, the
Following the judgment result that D ₁ ≦0, D ₂ is determined in step
Since it is judged as <0, move to step
Determine whether the amount of change in relative displacement X〓a at that time is X〓a≦0, and since X〓a≦0 at this time,
Shifting to step, a control signal CSa having a logic value of "1" for controlling the variable damping force shock absorber 6a to a low damping force is output to the drive transistor 34a.

Thereafter, at time t5, the amount of change in relative displacement It is output to the drive transistor 34a.

Furthermore, when the detected displacement value Xa enters the neutral region beyond time t6, following the judgment result of D ₁ ≦0 in step, it is judged that D ₂ ≧0, so the process moves to step. , a control signal CSa having a logic value of "0" for maintaining the variable damping force shock absorber 6a at a high damping force is continuously outputted to the drive transistor 34a.

Thereafter, at time t7, as in the case of time t1, the process proceeds to step after the step and step processing, and a control signal CSa of logical value "1" is applied to control the variable damping force shock absorber 6a to a low damping force. is output to the drive transistor 34a.

In this way, the damping force of the variable damping force shock absorber 6a is continuously increased from time t5 to time t7, thereby exerting a damping effect to prevent changes in the vehicle's attitude and improve riding comfort. can be improved.

Similar damping force variable shock absorber 6a
By repeating this control, changes in the posture of the vehicle can be suppressed and ride comfort can be improved. In addition, although the case where only the wheel 5a passes an uneven road surface has been described above, when the other wheels 5b to 5d pass an uneven road surface, the variable damping force shock absorbers 6b to 6d are controlled in the same way as described above. be done.

According to the above embodiment, the detected displacement amount of the relative displacement between the cylinder tube 7 and the piston rod 8 is
When Xi is displaced in the excitation direction away from the neutral position (displacement _amount When the amount of force transmitted to the vehicle body is reduced and the detected displacement value Xi is displaced in a direction approaching a neutral position with no attitude change with respect to the vehicle body, the damping force of the variable damping force shock absorber 6i is increased. The damping force is controlled to exhibit a damping effect, and when the detected displacement value Xi is within a neutral region of a predetermined width provided above and below the neutral position, the damping force is By correcting the control so as to decrease the detected vehicle speed value V when the detected vehicle speed value V is equal to or higher than the reference vehicle speed value K, the vibration damping effect of the vehicle body at low speeds and high speeds is improved, and the vehicle attitude is improved. The change can be effectively reduced and the riding comfort can be improved.

Incidentally, if the above-mentioned control according to the present invention is not performed, the change in the attitude of the vehicle when the wheel engages with the unevenness of the road surface is controlled by the variable damping force shock absorber 6.
If the damping force of i is increased, the vibration damping time can be shortened and a large damping effect can be achieved, but the degree to which road surface input is transmitted to the vehicle body increases, resulting in a large sprung mass displacement, and As a result, the vertical acceleration at the vehicle body floor also increases, giving the occupants a feeling of bumpy vehicle body vibration, leading to a problem in that ride comfort deteriorates. Furthermore, if the damping force of the variable damping force shock absorber 6i is reduced, the force transmitted to the vehicle body will be reduced, but the vibration damping effect will be reduced.
There was a problem in that the vibration damping time on the spring became long, and the riding comfort deteriorated as in the above case.

However, according to the present invention, as mentioned above, low damping force is given priority when driving at low speeds,
In addition, by performing control that prioritizes high damping force during high-speed driving, damping force control can be performed even if there is a detection error in the neutral position or a delay in the operation of the control valve, etc. in response to changes in relative displacement at the neutral position. In addition to being able to stabilize the vehicle, it is also possible to appropriately attenuate the excitation force at low and high speeds, effectively generating damping force against temporal changes in road surface irregularities, improving the vibration damping effect and improving riding comfort. can be improved.

In the above embodiment, a case has been described in which a detection coil is used as the displacement detection means 2a to 2d to detect the relative displacement between the cylinder tube 7 and the piston rod 8. However, the present invention is not limited to this. Instead, as shown in FIG. 10, a variable damping force shock absorber 6i
The vehicle body side member 4 at the tip of the piston rod 8 of
Even if the displacement amount detection signal shown in FIG. 11 is obtained by the piezoelectric element 42 inserted in the mounting portion 41 with the damping force variable shock absorber 6i, good.

In this case, when the vehicle overcomes temporary irregularities on the road surface, it is possible to detect the transmission force transmitted from the piezoelectric element 42 to the vehicle body with pitching and bouncing as shown in FIG. 12. Therefore, by inputting the displacement amount detection signal from the piezoelectric element 42 to the control device 3 of FIG. 2, the same effects as in the above embodiment can be obtained. Moreover,
Since the force transmitted to the vehicle body is directly detected using a piezoelectric element, there is less response delay than when detecting relative displacement, enabling accurate vibration damping control and ensuring excellent ride comfort. In addition, since the piezoelectric element 42 is used as the detection element, it has the advantage that it is not only easy to assemble but also can be constructed at low cost.

In addition, in FIG. 10, 43 is a coil spring, 44 and 45 are spring seats, and 46 is a mount insulator.

In addition, as other displacement detection means, it is possible to apply a displacement detection means such as a distance measuring device that measures the distance between the road surface and the vehicle body using ultrasonic waves installed at each wheel position of the vehicle body. can. Further, the variable damping force shock absorber 6i is not limited to the above configuration, and any variable damping force shock absorber may be used as long as it has a configuration that allows the damping force to be changed by inputting a control signal. be able to.

Furthermore, in the above embodiment, the vehicle speed detector 1 is used as the running state detector, but in addition, for example, a steering angle detector can be used. In addition to improving the riding comfort of the vehicle, the damping force is increased during steering to suppress changes in the vehicle's attitude and improve maneuverability, stability, etc.

Furthermore, the control device 3 is not limited to the above configuration, and may include a subtraction circuit, a comparison circuit,
It can also be configured with an electronic circuit such as a logic circuit, and the variable damping force shock absorber 6 can be configured by variously changing the current value of the control signal output from the control device 3 or by outputting pulse outputs with different duty ratios.
It is also possible to continuously change the damping force of i according to the transmitted force.

Furthermore, in the above embodiment, the _case where the neutral position displacement amount may be calculated.

〔Effect of the invention〕

As explained above, according to this invention,
The amount of relative displacement between the sprung portion and the unsprung portion of the vehicle based on the transmission force transmitted from the road surface to the vehicle body via the suspension is detected by the displacement amount detection means or the transmission force detection means, and the detected signal is sent to the direction determination means. This determines the direction of relative displacement of the variable damping force shock absorber, and based on the determination result, the control means displaces the damping force of the variable damping force shock absorber in a direction in which the relative displacement of the shock absorber moves away from the neutral position. When the relative displacement is moving in the direction approaching the neutral position, it is set high, and when the relative displacement is within a neutral area of a predetermined width provided above and below the neutral position by the neutral area setting means, the driving state detector The structure is such that the damping force of the variable damping force shock absorber is changed depending on the driving condition based on the detection signal. Therefore, even if there is a detection error in the neutral position or a delay in operation of the control valve that switches the damping force, the switching control of the damping force can be controlled even if the relative displacement of the variable damping force shock absorber changes in the neutral region due to unevenness of the road surface. This can be performed reliably and stably, and the excitation force during low-speed and high-speed travel can be appropriately attenuated. Therefore, it is possible to effectively generate damping force against temporal changes in road surface irregularities, improving the damping effect and improving ride comfort, as well as improving vehicle maneuverability and stability. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of this invention, FIG. 2 is a block diagram showing an embodiment of this invention, and FIG. 3 is a block diagram showing a schematic configuration of this invention.
FIG. 4 is a sectional view showing an example of a variable damping force shock absorber applicable to the present invention, FIG. 5 is a characteristic curve diagram showing its damping force characteristics, and FIG. 6 is a block diagram showing an example of displacement amount detection means. , FIG. 7 is a graph showing the relationship between the output voltage and the relative displacement, FIG. 8 is a flowchart showing an example of the processing procedure of the control device, FIG. 9 is a signal waveform diagram for explaining the operation of the present invention, and FIG. Fig. 10 is a sectional view showing another embodiment of the displacement detection means, Fig. 11 is a graph showing the relationship between the output voltage and the vehicle body transmission force, and Fig. 12 shows the output voltage waveform when overcoming unevenness on the road surface. It is a graph. 1...Vehicle speed detector (driving state detector), 2a~
2d...Displacement amount detection means, 3...Control device, 4a
~4d...Electromagnetic solenoid, 5a-5d...Wheel, 6a-6d...Variable damping force shock absorber, 7...Cylinder tube, 8...Piston rod, 11, 13...Fluid passage, 14...Through hole,
15...Spool, 17...Plunger, 21...
...Displacement detection coil, 22...LC oscillator, 23
...Frequency-voltage conversion circuit, 30...Microcomputer, 32...Multiplexer, 3...
A/D converter, 34a to 34d...drive transistor, 42...piezoelectric element.

Claims (1)

[Scope of Claims] 1. A driving condition detector that outputs a detection signal according to the driving condition of the vehicle, a variable damping force shock absorber that can change the damping force by inputting a control signal, and a variable damping force shock absorber that can change the damping force by inputting a control signal. Displacement or transmission force detection means that outputs a detection signal according to the relative displacement between the sprung and unsprung parts of the vehicle connected by the shock absorber or the transmission force to the vehicle body, and the relative displacement detected by the detection means. or a direction determining means for determining the direction of the transmitted force; a neutral region setting means for setting a neutral region of a predetermined width above and below a neutral position of the relative displacement of the shock absorber due to the relative displacement or the transmitted force; a control means for outputting the control signal that lowers the damping force when the relative displacement moves away from the neutral position and increases the damping force when the relative displacement moves towards the neutral position; when there is a relative displacement of the variable damping force shock absorber, the output of the control means is controlled by switching the damping force of the variable damping force shock absorber in accordance with the running condition based on the detection signal of the running condition detector. A shock absorber control device characterized by comprising: a correction means for: 2. The driving state detector is composed of a vehicle speed detector,
Claim 1, characterized in that the correcting means controls the output of the control means in accordance with the detected vehicle speed, so that the damping force is lowered when traveling at low speeds and increased when traveling at high speeds. Shock absorber control device.