JPS6189110A - Control device for shock absorber - Google Patents

Abstract

PURPOSE:To enhance the vibration damping effect of a vehicle, by adjusting the damping force of a shock absorber in accordance with the direction of relative displacement of the shock absorber, and by lowering the damping force when there is any relative displacement in the neutral range corresponding to the speed of the vehicle. CONSTITUTION:Displacement detecting means 2a through 2b are attached to shock absorbers 6a through 6b of variable damping force type, respectively. The direction of relative displacement between the upper and lower spring sides is determined in accordance with the amount of the displacement. Further, when the relative displacement is in the direction away from the neutral position, the damping force is decreased while when it is in the direction toward the neutral position, the damping force is increased. Further, when there is any relative displacement in the neutral range which is set around the neutral position by a neutral position setting means and which varies in accordance with the speed of the vehicle, the damping force is controlled to be set at a low value.

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 a 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, there is one disclosed in, for example, Japanese Patent 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 in order 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 adjust 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.

[Problem that the invention seeks to solve]

The conventional shock absorber control device described above is configured to control the damping force of the shock absorber in two stages, high and low, depending on the driving conditions, regardless of the shape of the road surface unevenness. There is a problem in that the transmitted excitation force cannot be appropriately attenuated, and phenomena such as rolling, pitching, or rolling back of the vehicle body occur due to the rocking of the vehicle body, making it impossible to improve riding comfort. In other words, if the shock absorber is controlled to a low damping force, even small vibrations due to the smoothness of the road surface cannot be suppressed completely, and if the shock absorber is controlled to a high damping force on a moderately rough road with some undulations. If the damping force is controlled to be too high, the damping force becomes unnecessarily high, whereas if the damping force is controlled to be low, the vehicle body will rock, which leads to a worsening of ride comfort.

[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 human power, and detection according to the amount of relative displacement between the upper and lower parts of the vehicle connected by this variable damping force shock absorber, or the force transmitted to the vehicle body. a displacement amount or transmission force detection means for outputting a signal; a direction determination means for determining the direction of the relative displacement or transmission force detected by the detection means; and neutralization of the relative displacement of the shock absorber due to the relative displacement or transmission force. neutral area setting means for setting a neutral area of a predetermined width above and below the position that changes according to the vehicle speed based on a detection signal from the vehicle speed detector; and a relative displacement of the shock absorber is displaced in a direction away from the neutral position. a control means for outputting a control signal that lowers the damping force when the shock absorber moves toward the neutral position and increases the damping force when the shock absorber moves toward the neutral position; The above-mentioned problem is solved by configuring a shock absorber control device including a correction means for controlling the damping force by switching it to a lower side regardless of the control signal when there is a displacement. The purpose is

[Effect]

Therefore, the present invention detects the amount of relative displacement between the upper and lower parts of the vehicle based on the transmission force transmitted to the vehicle body by a displacement amount detection means, or the transmission force to the vehicle body is detected by the transmission force detection means. Then, the detection signal is supplied to the direction determination means, which determines the direction of the 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 lowered, and when the relative displacement is moving closer to the neutral position, it is higher, and according to the vehicle speed of a predetermined width set above and below the neutral position by the neutral area setting means. By switching the damping force to the lower side when there is a relative displacement within the neutral range that changes due to the change in position, the transmission force that accompanies changes in the vehicle body posture is suppressed, improving the vehicle body distribution effect and improving the ride comfort of the vehicle. can be done.

〔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. 2 is a vehicle speed detector 28 to 2d that outputs a detection signal according to the vehicle speed.
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.

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

As shown in FIG. 4, each variable damping force shock absorber 6a to 6d has a piston 9 attached to the lower end of a piston rod 8 and a free piston 10 slidably disposed in a cylinder tube 7. The piston 9 and the free piston 10 cause the cylinder tube 7 to
The inside is defined into three fluid chambers A, B and C. 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 I whose upper end communicates with the fluid chamber A via a fluid passage 1 formed in the piston rod 8.
2, and a fluid passage 1 communicating with this and communicating with the fluid chamber B.
A cylindrical spool 15 having a through hole 14 communicating the two fluid passages 1 and 13 is slidably disposed in the center opening 12 of the spool 1.

This spool 15 is normally urged downward by a return spring I6, and its lower end surface contacts a plunger I7, and the lower end of this plunger 17 contacts the bottom surface of the case 18 to restrict its movement. In this state, the through hole 14 and the open end of the fluid passage 13 are connected to
Therefore, there is no communication between the two fluid passages 1) and 13, and the damping force is set to a high damping force as shown by the curve indicated by the solid line 1)H in FIG.

Further, the plunger 17 is energized by applying an excitation current Ia-wld to the electromagnetic solenoids 4a to 4d disposed around it by the control device 3 via the lead wire 19. a~ is moved upward in proportion to the IdO value. As a result, the spool 15 is displaced upward against the return spring 16, and the opening area between the fluid passages 1) and 13 formed by the through hole 14 is increased, and the damping force is increased as indicated by the dashed line 1L 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. The cylinder tube 7 and the piston rod 8 (that is, the relative displacement between the sprung portion and the unsprung portion of the vehicle) is wound with a displacement detection coil 21 that detects the relative displacement amount of the vehicle as an inductance change due to a change in the amount of overlap between the cover 20 and the cylinder tube 7. I am wearing it.

As shown in FIG. 6, the displacement detection coil 21 is embedded in the LC oscillator 22 as a coil that determines its oscillation frequency, and the LC oscillator 22 detects the relative displacement of the cylinder tube 7 and piston rod 8. An oscillation output with a frequency corresponding to the frequency is output.

The oscillation output is supplied to the frequency-voltage conversion circuit 23,
From this, a displacement detection signal S a % S d consisting of a voltage corresponding to the relative displacement between the cylinder tube 7 and the piston rod 8 as shown in FIG. 7 is output. These displacement detection coils 21, LC oscillator 22, and frequency-voltage conversion circuit 23 constitute displacement detection means 2a to 2d.

As shown in FIG. 2, the control device 3 has a microcomputer 30 having a human output port, a processing unit (CPU), storage devices such as RAM, ROM, etc. Vehicle speed detection signal DV of device I
is directly supplied, and each displacement detection means 2a~
2d displacement detection signal Sa-Sd is supplied via multiplexer 32 and A/D converter 33. Furthermore, the microcomputer 30 outputs a control signal C3a of logic value "0" or logic value "1" from the output side port.
~C5d is connected to the electromagnetic solenoid 4 of the variable damping force absorber 6a~6d connected to a DC power source (not shown).
Drive transistors 348~ inserted in series with a~4d
Output to 34d.

Then, the microcomputer 30 executes arithmetic processing according to a timer interrupt processing program, which is prestored in the ROM and shown in FIG. 8, and which is executed every 2Qmsec, for example.

That is, in step ■, the vehicle speed detection signal DV is read,
For example, the vehicle speed is calculated by measuring the number of pulses per unit time, 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 (3), where it is determined whether the vehicle is stopped. The determination in this case is made by reading out the detected vehicle speed value (2) stored in step (2) above, and determining whether or not (3) is O.

Here, when the vehicle is stopped, the process moves to step (2) and all variable damping force shock absorbers 6a to 6 are
A control signal (:,
Transistors 34a to 34d drive Sa-CS d.
After outputting , the program returns to the main program. On the other hand, when the vehicle is running, the process moves to the damping force control process from step (3) onwards.

The damping force control process first reads the detection signals 5ansd of the respective displacement detection means 2a to 2d in step (3), and converts them into displacement detection values Xi (i-a, b, c, and d).
) is temporarily stored in a predetermined storage area of the storage device. Next, the process proceeds to step (2), where the amount of displacement per unit time, which is the differential value of the detected amount of displacement value Xi, ie, the change fi
xi (i=a.

b, c and d).

Next, the process moves to step (2), where the detected vehicle speed value (2) is read out, and based on the detected vehicle speed value (V), data is stored in the RAM of the storage device in advance.
The upper and lower limit values of the neutral region setting amount δ are determined by referring to a neutral region setting amount lookup table stored in a predetermined storage area of (or ROM). These upper and lower limits change depending on the vehicle speed, and at low speeds, the relative displacement of the variable damping force shock absorber 61 is set widely in the direction away from the neutral position, and as the vehicle speed increases, the relative displacement of the damping force variable shock absorber 61 is set widely (in the direction) Set so that the width is narrow.The upper limit value +δ and lower limit value -δ of the neutral area setting amount are set in a large number in stages according to the vehicle speed, or are set in a stepless manner corresponding to each vehicle speed. Then, each of them is stored in a predetermined storage area of the storage device.

Next, the process moves to step (3), and the displacement amount Xn at the neutral position, which is the boundary position between the extension side and the contraction side, of each variable damping force shock absorber 5i (i=a, b, c, and d) is determined by A predetermined neutral region setting amount δ set on the extension side from the position is added, and the added value (XN + 6) is subtracted from the displacement amount detection value Xi stored in step (2) to calculate a difference value Di. It is determined whether the difference value D1 is positive or negative. In this case, the determination is made by determining whether the relative displacement between the cylinder tube 7 and the piston rod 8 is in the extension side region excluding the extension side neutral region (XN to 10δ) of the shock absorber 61. If the detected displacement value Xi is not in the extension temporal region excluding the extension side neutral region and Dl>O is not satisfied, the process moves to step (2).

In step (2), contrary to the determination in step (2), 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 each variable damping force shock absorber 61, and the subtraction is performed. The difference value D2 is calculated by subtracting the value (XN-6) from the detected displacement value Xi stored in step (2), and it is determined whether the difference value D2 is negative or positive. In this case, it is determined whether the relative displacement between the cylinder tube 7 and the piston rod 8 is in the contraction temporal region excluding the contraction side neutral region (XN--δ) of the shock absorber 61. In a state where the relative displacement detection value Xi is not in the contraction temporal region excluding the contraction side neutral region □ and Dl<0, the process moves to step ■.

In this step (2), a control signal C3i (i=a, b, c, and d) with a logical value of "1" for controlling each variable damping force shock absorber 61 to a low damping force is output to the drive transistor 34i. Ends the interrupt processing and returns to the main program.

In this way, when the relative displacement detection value Xi of each damping force variable shock absorber 61 is in the neutral area (+δ to − illusion) from the extension side neutral area setting amount to the contraction side neutral area setting amount, each damping force The damping force of the variable shock absorber 61 is lowered.

On the other hand, when the determination result of the step (■) is Dl>0, the process moves to step [phase], reads the amount of change xi stored in the step (2), and the value is positive (including 0).
Determine whether it is negative.

The determination in this case is to determine whether the change txi in the relative displacement of the shock absorber 61 is a displacement away from the neutral position or a displacement toward the neutral position, The judgment result is
When i≧0, move to step ■ and attenuate.
A control signal C3i having a logical value of "1" that controls the variable force shock absorber 61 to a low damping force is applied to the drive transistor 34i.
Further, when Xi≧0 is not satisfied, the process moves to step 0, and a control signal CSi of logical value "0" for controlling the variable damping force shock absorber 61 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 determination result in step ■ is D2<0, the process moves to step [phase], reads the change fLXi stored in step ■, and determines whether the value is negative (including 0) or positive. Determine whether The determination in this case is also the same as in the case of step [phase].
It is determined whether the amount of change Xi is a displacement in a direction away from the neutral position or a displacement in a direction approaching the neutral position, and the determination result is Xi≦
When the damping force is 0, the process moves to step (3) and a logical value "" for controlling the variable damping force shock absorber 61 to a low damping force is set.
A control signal C3i with a logic value of "0" is output to the drive transistor 34i, and when Xi≦0, the process proceeds to step (2) to control the variable damping force variable absorber 61 to a high damping force. C3i is output to the drive transistor 34i. Thereafter, each interrupt process is completed and the process returns to the main program.

Here, the process of step ■ constitutes a neutral region setting means, the process of steps ■ and step ■ constitutes a correction means, the processes of step ■ and step ■ constitute a control means, and furthermore, the process of step [phase] The processing of step 0 constitutes a direction determining means.

Next, the effect will be explained.

Assume that the vehicle is currently in a parked or stopped state, and in this state, when the interrupt process shown in FIG. 8 is executed at predetermined intervals, the vehicle speed detector is The vehicle speed detection signal DV of No. 1 is read, and the vehicle speed detection value ■ is calculated based on this. At this time, the vehicle is stopped, so
= 0, and it is determined that the damping force is in the middle at step (2), and then the process proceeds to step (2), where all variable damping force shock absorbers 5i (i = a, b, c, and d) are controlled to high damping force. A control signal C3i with a logic value of "0" is output to each drive transistor 34i.

In this way, each drive transistor 34i has a logic value of "0".
When the control signal C5i is supplied, these drive transistors 34i are turned off, the supply of excitation current to the electromagnetic solenoids 41 of each variable damping force shock absorber 61 is cut off, and each electromagnetic solenoid 41 is turned off. maintained in a stable condition.

As a result, the spool 15 is held in the lowered position by the return spring 16, so that the through hole 14 and the fluid passage 13 are held at a position W apart from each other, and the two fluid passages 1
) 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 61 is increased. Therefore, when the vehicle is stopped, it is possible to prevent the vehicle body from being tilted due to passengers getting in and out of the vehicle or loading and unloading cargo, and it is possible to maintain a stable vehicle body posture.

The stop side '41■ state resulting from steps (2) to (2) 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 speed detection value ■ calculated in step ■ becomes V≠0.
becomes. Therefore, the process moves from step ■ to step ■, and each detection signal Si of each displacement detection means 21 representing the relative displacement between the cylinder tube 7 and piston rod 8 of each variable damping force absorber 61 is read. , these are stored in a predetermined area of the storage device as the displacement amount detection value Xi of the relative displacement.
A differential value xi of the detected displacement value Xi is calculated and temporarily stored in a predetermined storage area.

Next, proceed to step (2), refer to the neutral area setting amount lookup table stored in advance in the storage device, and set the neutral position above and below the neutral position in accordance with the detected vehicle speed value (2) calculated in step (3). The extension side neutral area setting amount 10δ, which is the upper limit value of the neutral area to be applied, and the contraction side neutral area setting amount -δ, which is the lower limit value, are determined.

Here, when the vehicle is traveling at a low speed, the control device 3 operates in the low speed control mode shown in, for example, FIG.
The damping force of each variable damping force shock absorber 61 is switched and controlled as in the high speed control mode shown in FIG.

That is, by the processing of step ■ and step ■,
Whether the current displacement detection value Xi of the relative displacement between the cylinder tube 7 and the piston rod 8 is within the neutral region that changes depending on the vehicle speed set above and below the neutral position, or on the extension side set above the neutral region in the head area (excluding the neutral area on the extension side) or in the contraction temporal area (excluding the neutral area on the extension side), or in the contraction temporal area (excluding the neutral area on the extension side), or
(excluding the contraction side neutral region).

Thus, when the temporal region is in extension, the processing in step [phase] is used, and when the temporal region is in contraction, the processing in step @ causes the relative displacement to move away from the neutral position or approach the neutral position. In the former case, the damping force of the variable damping force shock absorber 61 is lowered, and in the latter case, the damping force is increased. When the detected displacement value Xi is within the neutral range, the variable damping force shock absorber 61 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 an unevenness on the road surface, the cylinder of the variable damping force shock absorber 6a is affected by the amount of relative displacement of the curved shape shown in FIG. 9(a), for example. When the tube 7 and the piston rod 8 relatively fluctuate, the detected displacement value X
When a is larger than the neutral position displacement fflXN but smaller than the neutral region setting amount δL corresponding to the current vehicle speed,
That is, when it is within the neutral region on the extension side (XN~+δL), it is determined that DI ≦0 in step ■, and then it is determined that D2≧O in step ■, so the process moves to step ■, and as shown in FIG. As shown in bl, a control signal C3a having a logical value of "1" is output to reduce the damping force of the variable damping force shock absorber 6a.

In this way, each drive transistor 34i has a logical value of "1".
When the control signal C3i of
ffl will be charged. Therefore, since each electromagnetic solenoid 41 is energized, the plunger 17 is raised, and the spool 14 is raised against the return spring 16, and the opening area between the through hole 14 and the fluid passage 13 is increased, and the fluid The flow resistance between the passages 1) and 13 is reduced, the working fluid can easily flow between the fluid chambers A and B, and the damping force of the variable damping force shock absorber 61 is reduced.

As a result, the ride comfort during normal driving can be improved, and the transmission force in the vibration direction transmitted to the vehicle body can be suppressed.

Thereafter, the interrupt process is completed 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.

Next, when the detected displacement value Xa exceeds the extension side neutral region setting amount δ and moves to the extension temporal region at time LIL,
Since it is determined in step (2) that DI>O, the process moves to step [phase] and it is determined whether the change ff1xa per unit time is 0 or more. As a result, until a certain point t2 when Xa=O, the relative displacement detection value Xa increases in the direction away from the neutral position displacement amount XN, so it is determined that Xa≧0 in step [phase]. , step ■
Then, as shown in FIG. 9(b), the control signal C3a of logical value "1" for maintaining the damping force of the variable damping force shock absorber 6a on the low side is continuously output.

When the detected displacement value Xa between the cylinder tube 7 and the piston condom 8 changes from this vibration control state in the direction toward the neutral position displacement fXN beyond time t2, the amount of change ga, which is the differential value of the relative displacement, changes. Since ga<Q, we move from step [phase] to step ■ and proceed as shown in Figure 9 (bl
As shown in FIG. 3, a control signal C3a having a logical value of "0" is output to increase the damping force of the variable damping force absorber 6a.

In this way, when the control signal C3a with the logic value "0" is supplied to the drive transistor 34a, the drive transistor 34a is turned off as described above, so that the electromagnetic solenoid 4a of the variable damping force shock absorber 6a is excited. The current supply is cut off, and the electromagnetic solenoid 4a
is maintained in a non-energized state. Therefore, since the spool 15 is held in the lowered position by the biasing force of the return spring 16, the through hole 14 and the fluid passage 13 are held in the assembled position, and the flow between the two fluid chambers A and B is maintained. The resistance increases, and the damping force of the variable damping force shock absorber 6a is increased. As a result, a large distribution effect is exhibited, and changes in the attitude of the vehicle body are prevented.

After that, at time t3, when the relative displacement detection value Xa exceeds the neutral displacement amount δ on the extension side to the lower side and shifts to the neutral region,
The process moves from step (2) to step (2), and it is determined whether or not the detected displacement value Xa at that time satisfies Xa<O. At time t3 when the transition to the neutral region is reached, D2≧0, so the process moves to step (2), and the damping force of the variable damping force shock absorber 6a is controlled to a low damping force, as shown in FIG. 9 fb). A control signal C3a with a logic value of "1" is output to the drive transistor 34a. As a result, the damping force of the variable damping force shock absorber 6a is reduced, so the transmission force in the excitation direction transmitted to the vehicle body is suppressed, and a change in the posture of the vehicle body is prevented.

This low damping force state starts from the neutral position setting amount δ before the neutral position displacement amount Control can be performed reliably and stably, 1);I
Changes in the posture of the vehicle body can be effectively suppressed.

After that, at time t4, when the detected displacement value Xa passes through the neutral region and passes the contraction side neutral region setting ■δ to the lower side and moves to the contraction side region, D2 is determined to be 0 in step ■. Move to step @ and change the relative displacement m xa
It is determined whether Xa≦0, and since Xa≦0 until time L5, the process moves from step @ to step ■, and a logical value is set to set the variable damping force shock absorber 6a to a low damping force. The control signal C5a of "I" is continuously outputted to the drive transistor 34a.

Next, after time t5, the change mxa in relative displacement becomes X
Since a>0, the process moves from step @ to step (2), and a control signal C3a with a logical value of "0" that makes the variable damping force shock absorber 6a have a high damping force is applied to the drive transistor 3.
Output to 4a. Therefore, the damping force of the variable damping force shock absorber 6a is increased, thereby exerting a large vibration damping effect and preventing changes in the attitude of the vehicle body.

This high damping force state continues until time t6, and
When L is reached and the amount of change in relative displacement Xa exceeds the contraction side neutral region setting meter -δL to the higher side and enters the neutral region, it is determined that Di ≦0 in step ■, and then D2≧ in step ■
Since it is determined that the damping force is 0, the process moves to step (3) and a logical value "1" is set to set the variable damping force shock absorber 6a to a low damping force.
” outputs the control signal C3a to the drive transistor 34a. Therefore, the variable damping force shock absorber 6
The damping force of a is reduced again, the transmission force in the excitation direction transmitted to the vehicle body is suppressed, and a change in the posture of the vehicle body is prevented.

Thereafter, at time tk, similar to the time tIL, control No. 13 C3a of logic value "1", which controls the variable damping force shock absorber 6a to a low damping force, continues and is output to the drive transistor 34a.

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

On the other hand, when the vehicle is running at high speed,
1, the upper limit value of the neutral area set above and below the neutral position, the extension side neutral area setting amount +δH, and the lower limit value, the contraction side neutral area setting amount −δH, respectively change the neutral displacement depending on the vehicle speed. It is displaced in the direction approaching the amount XN. Therefore, the time tlL is displaced to the time tl+, the time t, 3L is displaced to the time t3+, the time t4L is displaced to the time t4+, the time t6L is displaced to the time t6+, and further, the time t7L is displaced to the time t7+, and the same as above is performed. Performs switching control.

As a result, at low speeds, as shown in FIG. 9(b), the variable damping force shock absorber 61 is controlled to a low damping force as the upper and lower neutral area setting amount δ which determines the width of the neutral area increases. It takes a long time (as a result, an overall soft suspension feeling can be obtained, and the transmission force in the excitation direction transmitted to the vehicle body can be suppressed to prevent changes in the posture of the vehicle body.

Furthermore, at high speeds, as shown in FIG. 9 (C1), as the neutral region setting amount δH decreases, the time for controlling the variable damping force shock absorber 61 to a high damping force increases, resulting in an overall hard suspension feeling. It is possible to obtain a large distribution effect and prevent changes in the posture of the vehicle body.Therefore, in response to temporal changes in road surface irregularities, the excitation force transmitted to the vehicle body can be adjusted appropriately according to the vehicle speed. This can improve ride comfort.

In addition, in the above description, the case where only the wheel 5a passes through an uneven road surface is explained, but when the other wheels 5b to 5d pass through an uneven road surface, the variable damping force shock absorbers 6b to 6d is controlled.

According to the above embodiment, the displacement detection value Xi of the relative displacement between the cylinder tube 7 and the piston rod 8 is the neutral position of the relative displacement (displacement 1XN
) to 21) When the excitation force riIJ4 is displaced, the damping force of the variable damping force shock absorber 61 is lowered, and the detected displacement value Xi approaches the neutral position with no attitude change with respect to the vehicle body. When the damping force variable shock absorber 61 is displaced, the damping force of the variable damping force shock absorber 61 is increased, and when the displacement detection value Xi is within the neutral range that is set above and below the neutral position and changes depending on the vehicle speed, the damping force is increased at that time. By switching to low damping force when the damping force is present, and maintaining the low damping force when the damping force is low at that time, priority is given to the low damping force and the ride comfort of the vehicle is improved. At low speeds, the width of the neutral area is widened to maintain a low damping force state for a long time, reducing the amount of force transmitted to the vehicle body due to road reaction force, and at high speeds, the width of the neutral area is narrowed to maintain a low damping force state for a long time. It is possible to maintain the damping force state for a long time and exert a damping effect, thereby effectively reducing changes in the attitude of the vehicle.

Incidentally, if the above control according to the present invention is not performed, the change in the attitude of the vehicle when the wheel engages with a concave part of the road surface is as follows:
Increasing the damping force of the variable damping force shock absorber 61 can shorten the vibration damping time and exhibit a large damping effect, but the degree to which road surface input is transmitted to the vehicle body increases, resulting in thick bumps. This appears as a displacement, and therefore the vertical acceleration at the vehicle floor also increases, giving the occupants a feeling of bumpy vehicle body vibration, leading to a problem of deterioration of riding comfort. In addition, damping horn variable shock absorber 6
If the damping force in step 1 is lowered, the force transmitted to the vehicle body will be reduced, but the damping effect will be reduced, the vibration damping time on the spring will be longer, and the same problem as described above will be that the riding comfort will deteriorate. there were.

However, according to the present invention, as described above, neutral regions whose width changes depending on the vehicle speed are provided above and below the neutral position of the relative displacement of the variable damping force absorber 61, and the detected displacement amount of the relative displacement is When Xi is in the neutral range, the damping force of the variable damping force shock absorber 61 is constantly lowered to improve riding comfort, and at low speeds, the period of low damping force is lengthened to increase the vibration direction transmitted to the vehicle body. By suppressing the transmitted force and extending the period of high damping force at high speeds, it is possible to exhibit a large vibration damping effect.

In addition, in the above embodiment, the displacement gauge and the protruding means 2a to
As 2d, use the detection coil to detect the cylinder tube 7.
Although a case has been described in which the relative displacement between the piston rod 8 and the piston rod 8 is detected, the present invention is not limited to this, and as shown in FIG. The piezoelectric element 42 inserted in the attachment part 41 to the vehicle body side member 40 at the tip obtains the displacement detection signal shown in Fig. 1), which is a voltage corresponding to the transmission force transmitted to the variable damping force shock absorber 61. You can do it like this.

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 detection signal from the piezoelectric element 42 to the control device 3 shown in FIG.
The same effects as in the above embodiment can be obtained. Furthermore, 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, and accurate allocation control can be performed, resulting in 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;
4 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. Furthermore, a variable damping force shock absorber 61
However, the present invention is not limited to the above configuration, and any variable damping force shock absorber can be applied as long as it has a configuration that allows the damping force to be changed by inputting a control signal.

Furthermore, the control device 3 is not limited to the above-mentioned configuration, and may be configured with an electronic circuit such as a subtraction circuit, a comparison circuit, a logic circuit, etc. It is also possible to continuously change the damping force of the variable damping force shock absorber 61 in accordance with the transmitted force by variously changing the value or by outputting pulse outputs with different duty ratios.

Furthermore, in the above embodiment, a case was explained in which the neutral position displacement i You may also do so.

〔Effect of the invention〕

As described above, according to the present invention, the displacement amount detection means or the transmission force detection means detects the relative displacement amount 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. The detection signal is supplied to the direction determining means, which determines the direction of the relative displacement of the variable damping force shock absorber.Based on the determination result, the control means adjusts the damping force of the variable damping force shock absorber to the shock absorber. When the relative displacement of the absorber moves away from the neutral position, it is lowered, and when the relative displacement moves closer to the neutral position, it is increased, and the neutral area setting means changes according to the vehicle speed set above and below the neutral position. When there is a relative displacement within the neutral region,
The variable damping force shock absorber is configured to always control the damping force to a low level. Therefore, in the neutral region where the relative displacement of the variable damping force shock absorber is small, the variable damping force shock absorber is always maintained at a low damping force, so that the overall characteristics of the suspension device can be made soft. Moreover, the neutral region that keeps the variable damping force shock absorber at a low damping force changes depending on the vehicle speed. It is possible to appropriately damp the damping according to the vibration damping effect, thereby improving the riding comfort as well as improving the maneuverability and stability of the vehicle.

[Brief explanation of drawings]

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, FIG. 3 is a block diagram showing a schematic configuration of this invention, and FIG. 4 is a block diagram showing the basic configuration of this invention. A sectional view showing an example of an applicable variable damping force shock absorber, FIG. 5 is a characteristic curve diagram showing its damping force characteristics, FIG. 6 is a block diagram showing an example of displacement detection means, and FIG. 7 is a relative diagram thereof. Graph showing the relationship between output voltage and displacement, No. 8
The figure is a flowchart showing an example of the processing procedure of the control device.
Fig. 9 is a signal waveform diagram for explaining the present invention in detail, Fig. 10 is a sectional view showing another embodiment of the displacement detection means, and Fig. 1) shows the relationship between the output voltage and the vehicle body transmission force. The graph shown in FIG. 12 is a graph showing the output voltage waveform when riding over uneven road surfaces. ■...Vehicle speed detector, 2a-2d...Displacement detection means, 3...Control device, 4a-4d.
...Electromagnetic solenoid, 5a to 5d...Wheel, 6a to 6d...Variable damping force shock absorber, 7...Cylinder tube, 8...
・Piston Rondo, 1). 13...Fluid passage,
14...Through hole, 15...Spool, 1
7... Plunger, 21... Displacement detection coil, 22... LC oscillator, 23...
...Frequency-voltage conversion circuit, 30...Microcomputer, 32...Multiplexer, 33
...A/D converter, 34a to 34d...
...Drive transistor, 42...Piezoelectric element

Claims (2)

[Claims] (1) A vehicle speed detector that outputs a detection signal according to vehicle speed;
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 parts of a vehicle connected by this variable damping force shock absorber, or the force transmitted to the vehicle body. a displacement amount or transmission force detection means for outputting a corresponding detection signal; a direction determination means for determining the direction of the relative displacement or transmission force detected by the detection means; and a direction determination means for determining the direction of the relative displacement or transmission force detected by the detection means; neutral region setting means for setting a neutral region of a predetermined width above and below a neutral position of displacement that changes according to a vehicle speed based on a detection signal from the vehicle speed detector; and a direction in which the relative displacement of the shock absorber moves away from the neutral position. a control means for outputting the control signal for lowering the damping force when the shock absorber is displaced toward the neutral position and increasing the damping force when the damping force is displaced toward the neutral position; A shock absorber control device comprising: correction means for controlling the damping force by switching it to a lower side regardless of the control signal when there is a displacement. (2) The neutral area setting means may set the predetermined width to be wider in a direction away from the neutral position at low vehicle speeds and narrower in a direction closer to the neutral position at high vehicle speeds, depending on the vehicle speed. Claim No. 1 (1) characterized by
Shock absorber control device described in ).