JPS61184114A - Controller for shock absorber - Google Patents

Abstract

PURPOSE:To improve the stability of body attitude and the maneuverability, in a controller for controlling the damping force of variable shock absorber with correspondence to the relative displacement between the upper and lower sections of spring, by controlling the damping force while considering the inner causes of the variation of body attitude. CONSTITUTION:In a controller having a variable shock absorber A between the upper and lower sections of spring for vehicle, means B for detecting the relative displacement between the upper and lower sections of spring and means C for detecting the variation of body attitude due to inner causes of vehicle are provided. While direction deciding means D for deciding whether said variation of relative displacement is in departing direction from the neutral position or suppressing direction is provided. Control means E will control the shock absorber A to high damping force when said variation is in departing direction under the condition where variation of body attitude will not occur while to high damping force when said variation is directing toward the neutral position under the condition where variation of body attitude will occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shock absorber control device that controls the damping force of a variable damping force shock absorber in accordance with the relative displacement of sprung and unsprung parts of a vehicle.

[Conventional technology]

As a conventional shock absorber control device, there is one described, for example, in Japanese Patent Application No. 106294/1983, which was previously proposed by the applicant of the present invention.

This system judges the unevenness of the road surface by the relative displacement between the sprung and unsprung parts of the vehicle, and the relative displacement is in the direction away from the neutral position (for example, the position when the vehicle is stopped on a flat, horizontal road surface). By controlling the variable damping force shock absorber to a low damping force in the direction (excitation direction) and high damping force in the direction toward the neutral position (allocation direction), the variable damping force shock absorber is controlled to a high damping force. It effectively exhibits a vibration damping effect and significantly improves riding comfort.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional shock absorber control device, the vehicle body bottoms due to temporary unevenness formed on the road surface, bounces the vehicle body when driving on a undulating road, and adjusts the vehicle body according to the road surface condition such as when driving on a rough road. The aim is to perform control that emphasizes riding comfort with respect to the vertical movement of the vehicle, and the variable damping force shock absorber is configured to be controlled to a high damping force only when the relative displacement is in the damping direction away from the neutral position. , vehicle internal disturbances such as rolling during steering, nose dive during sudden braking, and scat during sudden start, i.e. changes in vehicle body posture caused by operator operations, do not suppress these but instead promote sinking. As a result, maneuverability and stability are reduced, and control is performed that makes it easier to leave the neutral position and, conversely, makes it difficult to return to the neutral position, resulting in a delay in return after changes in vehicle body posture such as rolling. There was a problem.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention, as shown in the basic configuration diagram of FIG. A shock absorber control device that controls the damping force of a variable damping force shock absorber according to the relative displacement between the sprung mass and the sprung mass, comprising: relative displacement detection means for detecting the relative displacement between the sprung mass and the sprung mass; , a vehicle body posture change detection means for detecting a change in vehicle body posture due to internal factors of the vehicle, and whether a change in relative displacement is in a direction away from a neutral position or in a damping direction based on a detected value of the relative displacement detection means. When the detection result of the direction determination means for determining whether the vehicle body attitude change is in a direction that does not cause a change in the vehicle body attitude, the attenuation is performed only when the determination result of the direction determination means is in a direction away from the neutral position. A control signal for controlling the variable force shock absorber to a high damping force is output, and when the detection result of the vehicle body attitude change detection means is a state that causes a change in the vehicle body attitude, the determination result of the direction determination means is directed toward a neutral position. and control means for outputting a control signal for controlling the variable damping force shock absorber to a high damping force only when the variable damping force shock absorber is in the direction shown in FIG.

[Effect]

This invention detects the relative displacement between the sprung mass and the unsprung mass of the vehicle using a relative displacement detection means, and determines whether the direction of change of the detected relative displacement value with respect to the neutral position is in the direction away from the neutral position or in the direction towards the neutral position. The direction determining means determines whether there is a change in the attitude of the vehicle due to an internal factor based on the operator's operation, and the attitude change detecting means detects a change in the attitude of the vehicle due to an external factor due to the road surface condition. The control means controls the variable damping force shock absorber to a high damping force only when the determination result of the direction determining means is in the direction toward the neutral position, thereby reducing the change in attitude of the vehicle body, and conversely, the change in attitude detecting means causes rolling. When it is detected that a change in the vehicle body posture is caused by internal factors such as The system controls changes in the vehicle body's attitude and speeds up its return to the neutral state, thereby effectively suppressing changes in the vehicle's attitude caused by both external factors such as road surface conditions and internal factors such as rolling. Satisfies both riding comfort and handling/stability.

〔Example〕

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

First, the configuration will be explained. In Figure 2, la,
lb is a front wheel, lc and ld are rear wheels, 2 is a vehicle body, and variable damping force shock absorbers 4a to 4d are interposed between each of the wheels 1a to 1d and the vehicle body 2.

An example of these variable damping force shock absorbers 4a to 4d, as shown in FIG. The piston 6 and the free piston 8 define fluid chambers A, B, and C.

These fluid chambers A and B are filled with a working fluid such as hydraulic oil, and the fluid chamber C is filled with high pressure gas.

The piston rod 7 is connected to the upper piston rod 7 in the axial direction.
U and a lower piston rod 7L, and the lower piston rod 7L bypasses the piston 6.
A bypass path 9 is formed that directly communicates the fluid chambers A and B, and an actuator 12 having an electromagnetic solenoid 10 and a plunger 11 is provided on the upper piston rod 7U.
It's decorated. The plunger 11 is an electromagnetic solenoid 1
0 is in the biased state, it takes a downward position against the return spring 13, and in this state, the bypass passage 9 is closed by its lower end, and the variable damping force shock absorbers 4a to 4d have a high damping force. The damping force characteristics shown by curves 1 and 1 in FIG. 4 are obtained. When the electromagnetic solenoid 10 is in a non-energized state, the return spring 13 takes the upper position, opens the bypass path 9, and sets the damping force to a low level, so that the damping force characteristic shown by the curve LL in FIG. 4 is achieved. can get.

In FIG. 3, 14 and 15 are damping force generating orifices on the contraction side and expansion side, respectively, and 16 and 17 are non-return pulps.

Further, 21 is a variable damping force shock absorber 4a to 4d.
This damping force selection switch is located near the driver's seat and has a manually operated low damping force and high damping force selection position, and an automatic damping force control position. A selection switch signal corresponding to the selected position is output.

Reference numeral 22 denotes a vehicle speed sensor, which has the configuration of a rotation detector that magnetically and optically detects the rotation speed on the output side of the transmission, for example, and outputs a pulse signal according to the vehicle speed.

23 is a steering angle sensor, and the steering wheel 2
The steering wheel 3a is disposed around a steering shaft 23b connected to the steering wheel 3a, and outputs a digital signal according to the steering angle of the steering wheel 23a.

Reference numeral 24 denotes a throttle opening sensor, which outputs a digital signal corresponding to depression of the accelerator pedal.

A brake switch 25 outputs a switch signal depending on the depression state of a brake pedal (not shown).

On the other hand, each of the variable damping force shock absorbers 4a to 4d
Relative displacement detection means 268 to 26d for detecting the relative displacement between the cylinder tube 5 and the piston loft 7, that is, the relative displacement between the unsprung portion and the unsprung portion of the vehicle are disposed.

Each of these relative displacement detection means 26a to 26d has a third
As shown in the figure, there is a cylindrical cover 27 that is integrally attached to the upper end of the piston rod 7 and whose lower end reaches and covers the cylinder tube 5, and a cylinder tube that is wrapped around the inner peripheral surface of the cover 27. 5 and the piston rod 7 (i.e., the sprung mass-unsprung mass relative displacement N of the vehicle),
It has a displacement detection coil 28 that detects a change in inductance due to a change in the amount of overlap between the cover 27 and the cylinder tube 5. As shown in FIG. 5, this detection coil 28 is incorporated into an LC oscillation circuit 29 as a coil for determining its oscillation frequency.
An oscillation output with a frequency corresponding to the relative displacement position X of the cylinder tube 5 and the piston loft 7 (i.e., the relative displacement 1i between the unsprung part and the unsprung part) is output, and this oscillation output is supplied to the frequency-voltage conversion circuit 30. From this, a displacement detection signal Sa xSd having a voltage according to the relative displacement 1x as shown in FIG. 6 is output.

The damping force selection switch 21 and the vehicle speed sensor 22
, the output signals of the steering angle sensor 23, the throttle opening sensor 24, and the brake switch 25, and the relative displacement detection means 2
Relative displacement detection signals 5axSd of 6a to 26d are input to the control device 31, respectively.

As shown in FIG. 7, this control device 31 includes an input/output board, an arithmetic processing unit (CPU), and a RAM.

It has a microcomputer 32 having a storage device such as a ROM, and inputs the switch signal DW of the damping force selection switch 21, the vehicle speed detection signal DV of the vehicle speed sensor 22, and the steering angle detection signal Dθ of the steering angle sensor 23. , throttle opening detection signal DS of throttle opening detection 24,
The braking state detection signal DB of the brake switch 25 is supplied via the waveform shaping circuit 33, and the displacement detection signal 5a=Sd of each displacement detection means 26a to 26d is supplied to the multiplexer 34 and the A/D converter 35. The control signals C3a to C3d with a logic value of "0" or logic value "1" supplied through the output boat and outputted from the output side boat are applied to the electromagnetic solenoids of the variable damping force shock absorbers 4a to 4d to a DC power source (not shown). It outputs to drive transistors 36a-36d interposed in series with 10a-10d.

The microcomputer 32 executes predetermined arithmetic processing according to a processing program stored in advance in the RoM of the storage device, and first selects manual damping force control or automatic damping force control based on the switch signal of the damping force selection switch 21. When manual damping force control is selected, the variable damping force absorbers 4a to 4d are controlled to high damping force or low damping force according to the selection, and when automatic damping force control is selected, the vehicle speed sensor 22, Based on detection signals from the steering angle sensor 23, throttle opening sensor 24, and brake switch 25, changes in vehicle body posture due to internal factors caused by operations by the driver are detected. That is, it is determined based on the steering angle detection signal Dθ whether the vehicle will be in a rolling state with a large attitude change, and based on the throttle opening detection signal DS whether a scant phenomenon due to sudden acceleration or a nose dive phenomenon due to sudden deceleration will occur. Based on the brake inch signal, it is determined whether a nose dive phenomenon occurs due to sudden braking.

When it is predicted that a change in the vehicle body posture will occur due to the internal factors caused by the driver's operation, the microcomputer 32 determines whether the change in relative displacement between the unsprung mass and the sprung mass at that time is from the neutral position. It is determined whether the direction is away from the neutral position or toward the neutral position, and the variable damping force shock absorbers 4a to 4d are controlled to a high damping force only when the direction is away from the neutral position. When the control signals C3a to C3d are output and a change in vehicle body posture due to the internal factors is not predicted,
Outputs a control signal C3a = C5a with a logical value °l that controls the variable damping force shock absorbers 4a to 4d to a high damping force only when the change in relative displacement between the unsprung part and the unsprung part is in the direction toward the neutral position. do.

Next, the operation will be explained with reference to a flow chart showing the processing procedure of the microcomputer shown in FIG.

Now, assuming that the damping force selection switch 21 is manually set to the high damping force selection position, in this state,
First, in step (2), the switch signal of the damping force selection switch 21 is read, and then, in step (2), it is determined whether or not the damping force selection switch 21 has selected the manual high damping force selection position. At this time, since the high damping force selection position has been selected, the process moves to step (2), and a control signal C3a=C3d with a logical value of "1" controls all variable damping force shock absorbers 4a to 4d to high damping force. is outputted to the drive transistors 36a to 36d, and then the process returns to step (2).

In this way, when the control signals C3a to C3d with a logic value of "1" are output to the drive transistors 36a to 36d, these drive transistors are turned on, and the electromagnetic solenoid 10a of each variable damping force shock absorber 4a to 4d is turned on.
~10d is energized and becomes energized. Therefore, the plunger 11 descends against the return spring 13 and closes the bypass passage 9, and the fluid chambers A and B are communicated only through the extension side and contraction side orifices 14.15, and the damping is reduced. Force variable shock absorber 4a~4
d is controlled to a high damping force.

In addition, when the damping force selection switch 21 is manually set to the low damping force selection position, the process moves from step ① to step ② to check whether the damping force selection switch 21 is selected to the low damping force selection position. Since this has been selected, control signals C3a-C3d of logical value "0" for controlling all variable damping force shock absorbers 4a-4d to low damping force are applied to the drive transistor 36a. ~36d. In this way, when the control signal C3a=C3d with the logical value "0" is output to the drive transistors 36a to 36d, these drive transistors 36a to 36d are turned off, and the electromagnetic solenoid 1
Since 0a to 10d are in a non-energized state, the plunger 11
takes the upper position by the return spring 13, and the bypass path 9 becomes open. For this reason, fluid chambers A and B
Since the space is communicated by the bypass passage 9 in addition to the extension side and contraction side orifices 14.15, each of the variable damping force shock absorbers 4a to 4d is controlled to have a low damping force.

Furthermore, when the damping force selection switch 21 is set to the automatic damping force control position, the process proceeds to automatic damping force control processing through steps (1), (2), and (2).

This automatic damping force control process first reads the vehicle speed detection signal DV from the vehicle speed sensor 22 in step (3), and calculates the vehicle speed by counting the number of pulses per unit time or by measuring the pulse interval time. , this is the vehicle speed detection value V
It is temporarily stored 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 determining whether or not the detected vehicle speed value (2) read in step (2) is zero.

At this time, when the vehicle is stopped, the process moves to step (3) and all variable damping force shock absorbers 4a are
~4d is controlled to a high damping force.

In this way, when the damping force variable shock absorber 4
When a to 4d are controlled to a high damping force, it is possible to prevent the vehicle body from shaking due to changes in load when passengers get on and off or when loading and unloading luggage, and it also prevents the vehicle from shaking back when the brake pedal is depressed and the vehicle is stopped. Can be suppressed.

Further, when the brake pedal is depressed while the vehicle is running at a required speed to bring the brake into a braking state, the process moves from step (2) to step (2), and it is determined whether or not the vehicle is in a sudden braking state. In this case, sudden braking is determined as shown in FIG. 9(a). First, in step (a), the multiplexer 34 is driven to read the switch signal from the brake switch 25, and then, the process proceeds to step (b). Based on the switch signal read in step (a), it is determined whether the brake pedal is depressed. At this time, since the brake pedal is being depressed, the process moves to step ■C, and the relative displacement detection signals Sa of the front wheel side relative displacement detection means 26a and 26b are
Read Sb, calculate the amount of change per unit time, and calculate this as the amount of change ΔX on the front wheel side.

It is temporarily stored in the RAM of the storage device.

Next, the process moves to step d, and the amount of change ΔXI on the front wheel side is
Determine whether I is greater than or equal to a predetermined set value α3, and determine ΔXi
When ≧α, it is determined that the brake is in a sudden braking state, and
The process moves to the vehicle body attitude change suppression process after step @.

In this vehicle attitude change suppression process, first, in step [phase], the detection signals Sa to Sd of the displacement detection means 2a to 2d are read, and these are converted into relative displacement detection values X1(i''a, b, c
and d), temporarily stored in a predetermined storage area of the storage device. Next, the process moves to step 0, and the differential value of the relative displacement detection value, that is, the relative displacement detection value i (ia, b, c, and d
) is calculated.

Next, proceed to step [phase], and calculate a neutral position by moving average based on the detected displacement value Xi stored in step @ and the past detected relative displacement value, and calculate the neutral position. RA of the storage device as the position detection value XNi
Temporarily stored in M. Next, the process proceeds to step (2), where the current relative displacement amount detection value Xi stored in step @ and the neutral position detection value XNi stored in step (2) are read out, and the difference value between the two, that is, the neutral of the relative displacement Position XNi
The amount of change Di is calculated and stored in a predetermined storage area of the storage device.

Next, the process moves to step [phase], and it is determined whether the amount of change Di is zero or a positive number. In this case, the judgment is to determine whether the relative displacement between the sprung mass and the unsprung mass is on the extension side or contraction side of the neutral position.In a sudden braking state, the relative displacement on the front wheel side is on the neutral side. The position is on the contraction side, and the relative displacement on the rear wheel side is on the expansion side compared to the neutral position. Therefore, for the front wheel side, D<0, so proceed to step O, and determine whether the relative displacement speed large i stored in step 0 is zero or a positive number, and at this time, Since the relative displacement changes in the direction away from the neutral position toward the contraction side, that is, in the excitation direction, the relative displacement speed large i becomes a negative number (statement i < 0), and the process moves to step @ to increase the variable damping force shock absorber 41. A control signal CSi with a logical value of "1" for controlling the damping force is output to the drive transistor 36i, and the corresponding variable damping force shock absorbers 4a and 4b on the front wheel side are controlled to a high damping force.

Further, for the rear wheel side, D, ≧O, so proceed to step [phase] and determine whether the relative displacement speed large i stored in step 0 is a negative number, and at this time, Since the relative displacement changes in the direction away from the neutral position toward the extension side, that is, in the excitation direction, the relative displacement velocity large i becomes a positive number (statement i
>O), proceed to the step [phase] and set the logical value "1" to control the variable damping force shock absorber 41 to a high damping force.
” control signal C3i is output to the drive transistor 36i, and the damping force variable shock absorber 4 of the corresponding rear wheel is controlled.
c and 4d are controlled to high damping force.

In this way, when the variable damping force shock absorbers 4a to 4d on the front wheel side and the rear wheel side are respectively controlled to high damping force during sudden braking, the resistance force in the direction away from the neutral position of relative displacement increases, and the nose It is possible to suppress sinking of the front wheel side vehicle body and lifting of the rear wheel side vehicle body due to the dive phenomenon, and it is possible to improve riding comfort.

In addition, the state in which the brake pedal is released and the state in which the brake pedal is depressed but the depression does not involve a change in the attitude of the vehicle body (i.e., the amount of change in the relative displacement of the front wheels ΔX)
8 is less than the predetermined set value α8, the process proceeds to step (3) without performing the sudden braking process.

Also, if the vehicle accelerates suddenly, step ■,■
, ■, and ■ to ■ to proceed to step ■, where sudden acceleration judgment processing is performed.

As shown in FIG. 9(b), the sudden acceleration determination process in this case reads the throttle opening detection signal DS of the throttle opening sensor 24 in step (a), and sets this as the current throttle opening detection 4ft s. The past throttle opening detection value S2 is temporarily stored in the RAM of the storage device, and then the past throttle opening detection value S2 stored last time is read out from the storage device RAM in step (b), and the difference value between the two is calculated based on this and the current throttle opening detection value SI. ΔS ("S'+Sz)" is calculated and temporarily stored in the RAM of the storage device.

Next, the process moves to step (2)C, and it is determined whether the difference value ΔS stored in step (2)b is a positive number or a negative number. At this time, since it is in a rapid acceleration state, ΔS>0,
It is determined that it is in an acceleration state, and the process moves to step d, where it is determined whether the difference value ΔS is greater than or equal to a predetermined set value α8. At this time, in the rapid acceleration state, ΔS≧α, so the process moves to the vehicle body attitude change suppression process from step 0 onwards. In this case as well, in a state of sudden acceleration, a so-called scufting phenomenon occurs in which the front wheels rise and the rear wheels sink, but in the initial state, the relative displacement of both the front and rear wheels is in the direction away from the neutral position. Therefore, for the front wheel side, from step [phase] to step [phase] to step [phase],
Regarding the rear wheel side, the process moves through step [phase] step O to step [phase], and eventually each of the variable damping force shock absorbers 4a to 4d is controlled to a high damping force state to suppress the scut phenomenon.

In addition, in a constant speed running state or a decelerating running state, which is not an acceleration state, a transition is made from step ■C or step ■d to step [phase], respectively.

Further, when the vehicle is running at a required speed and the accelerator pedal is suddenly released from an accelerating state to shift to a sudden decelerating state, steps ■ and ■ occur.

After going through steps ◎ and ◎ to ◎, the process moves to step ◎, where sudden deceleration judgment processing is performed.

In this sudden deceleration judgment process, as shown in FIG. 9(C), first, in step @la and [phase] b, the same processes as steps ■a and ■b in the sudden acceleration state process are performed, and then in step @lc It is determined whether or not the difference value ΔS is a negative number. At this time, since it is a sudden deceleration state, ΔS<0, and the process moves to step @ld, where the absolute value of the difference value ΔS is equal to the predetermined set value α. Determine whether or not it exceeds. In this case as well, 1ΔS1>α in a sudden deceleration state. Therefore, the vehicle body posture change suppression process after step [phase] is performed to control each damping force variable damping force absorber 4a to 4d to a high damping force to suppress the nose dive phenomenon caused by sudden deceleration.

In addition, when the vehicle is running, if the steering wheel 23a is suddenly turned and the vehicle rolls with a large change in attitude, the steps ■, ■, ■, ■~
0, the process moves to step (2), and role determination processing is performed.

As shown in FIG. 9(d), this roll judgment process first reads the steering angle detection signal Dθ from the steering angle sensor 23 in step Oa, and sets this as the current steering angle detection value θ to a predetermined value in the storage device. Temporarily stored in the storage area. Next, the process moves to step ■b, where the detected steering angle value θ1 stored in step ■a and the detected steering angle value θ2 stored in the previous process are read out, and the difference value Δθ (=θ1−θ2) between the two is calculated. This is calculated and temporarily stored in a predetermined storage area of the storage device. Next, the process proceeds to step (2)C, where it is determined whether the absolute value of the difference value Δθ is greater than or equal to a predetermined set value α. At this time, since the vehicle is in a roll state, 1Δθ1>α, and the process proceeds to the vehicle body attitude change suppression process from step 0 onward.

At this time, if the steering wheel 23a is turned to the right, for example, the vehicle body 2 will be tilted downward to the left, and the relative displacement between the left sprung mass and the sprung mass will be from the neutral position to the contraction side, and the right side It becomes the extension side from the neutral position.

Therefore, in the vehicle posture change suppression process, the left side of the vehicle body 2 goes from step [phase] to step [phase] to step [phase], and the right side goes from step [phase] to step O to step [phase]. As a result, each of the variable damping force shock absorbers 4a to 4d can be controlled to a high damping force, thereby achieving an anti-roll effect.

Assuming that there is no change in the posture of the vehicle body 2 due to internal factors based on the driver's operations as described above, step
, ■, ■, and ■ to ■ to proceed to external vehicle body posture change processing that suppresses changes in vehicle body posture caused by external factors such as road surface conditions after Ste/knob ■.

This external vehicle body posture change processing is performed in steps @~[phase]
has exactly the same steps [phase] to [stock], and when the determination result of step [phase] is ≧0, it moves to the step O, and when D, < 0, it moves to the step 0. do. For this reason, the process of suppressing changes in vehicle body posture due to internal factors is, conversely, performed when the relative displacement between the unsprung part and the unsprung part is on the extension side from the neutral position, that is, when ≧0 and the relative displacement speed is large i. is negative or <0 and the relative displacement speed Xi is zero or positive, damping that suppresses the change in attitude of the vehicle body toward the neutral position when the relative displacement between the sprung mass and the sprung mass is negative or <0 and the relative displacement speed Xi is zero or positive. It is determined that the damping force is in the correct direction, and the variable damping force shock absorbers 41 are respectively lowered to a high damping force.

In other cases, when ≧O and the relative displacement speed i is zero or positive, and when D5<0 and the relative displacement speed i is negative, the relative displacement between the sprung mass and the sprung mass It is determined that the displacement is in an excitation direction that causes the vehicle body to change its attitude away from the neutral position, and moves to each step [phase] where the damping force variable shock absorber 41 is controlled to a low damping force and the vehicle body changes its attitude. To minimize the force transmitted to the vehicle body that causes changes.

As a result, it is possible to effectively exert a vibration damping effect that suppresses changes in the posture of the vehicle body due to road surface conditions, such as bottoming conditions due to temporary irregularities formed on the road surface, undulating roads, bouncing conditions when driving on rough roads, etc. This makes it possible to suppress changes in vehicle body posture caused by external factors such as road surface conditions.

Here, the processing from step ■ to step ■ corresponds to a vehicle body posture change detection means for detecting a change in vehicle body posture due to internal factors, the processing at steps [phase] and [phase] corresponds to a direction determination means, and step O ~The processing in step O corresponds to the control means.

In addition, in the above embodiment, the displacement amount detection means 28 to 2
d, a case has been described in which a detection coil is used to detect the relative displacement between the cylinder tube 7 and the piston 70718, but the invention is not limited to this, and as shown in FIG. The voltage corresponds to the transmission force transmitted to the variable damping force shock absorbers 6a to 6d by the piezoelectric element 42 inserted in the attachment part 41 to the vehicle body side member 40 at the tip of the piston rod 8 of the variable shock absorbers 6a to 6d. The displacement amount detection signal shown in FIG. 11 may be obtained.

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. 7, it is possible to obtain the same effects as in the above embodiment. However, since the relative displacement is directly detected by the piezoelectric element 42 as a force transmitted to the vehicle body, there is less response delay than when relative displacement is detected using a detection coil, and accurate vibration damping control is performed. This makes it possible to ensure excellent riding comfort, and since the piezoelectric element 42 is used as the detection element, it has the advantage of being easy to assemble and being able to be constructed at low cost.

In addition, in FIG. 10, 43 is a coil spring;
4.45 is a spring seat, and 46 is a mount insulator.

Further, as other displacement amount detection means, each wheel 1a of the vehicle body
Any displacement detection means, such as a distance measuring device that measures the distance between the road surface and the vehicle body using ultrasonic waves, can be applied to a position in the vicinity of ~1d.

Furthermore, the damping force variable shock absorbers 4a to 4d are not limited to the above configuration, and the damping force can be adjusted to 3.
It is possible to apply a type that allows switching control in more than one step, a type that allows stepless control of the damping force, etc. In short, there is a configuration that can change the damping force to at least two levels, high and low, by inputting a control signal. Any variable damping force shock absorber can be applied as long as it is.

Furthermore, the control device 31 is not limited to the above configuration, and can be configured by combining electronic circuits such as a subtraction circuit, a comparison circuit, and a logic circuit. It is also possible to continuously change the damping force of the variable damping force shock absorbers 6a to 6d according to the relative displacement between the sprung mass and the unsprung mass by varying the current value or outputting pulse outputs with different duty ratios. It is.

Furthermore, in the above embodiment, a case has been described in which the neutral position detection value can be detected and used as the neutral position detection value XNi, or a predetermined set value can be stored in advance.

Furthermore, in the embodiment described above, three types of vehicle body posture change detection means, namely a steering angle sensor 23, a throttle opening sensor 24, and a brake switch 25, are used as vehicle body posture change detection means for detecting a change in vehicle body posture due to internal factors caused by the driver's operation. Although the case where a detection means is provided has been described, it is also possible to provide only one of these detection means, and the detection of sudden acceleration, sudden braking, and sudden deceleration can be performed by using the vehicle speed detection of the vehicle speed sensor 22. It is also possible to calculate and detect the amount of change per unit time in the detected vehicle speed value based on the signal, and also to detect the detection signal of an acceleration detector installed on the vehicle body that detects acceleration in the longitudinal direction, lateral direction, and vertical direction. It can also be used to detect changes in vehicle body posture due to internal factors.

Furthermore, in the above embodiment, when a change in the attitude of the vehicle body occurs due to internal factors, a timer can be set at the latter stage of the step [phase], and the high damping force state can be maintained until the timer times out. In this case, there is an advantage in that it is possible to reliably prevent swinging back after a posture change due to internal factors.

〔Effect of the invention〕

As explained above, according to the present invention, when the relative displacement between the sprung mass and the unsprung mass is in the excitation direction away from the neutral position, a change in the vehicle body posture due to internal factors caused by the operator's operation is detected. , the variable damping force shock absorber is controlled to a high damping force, and when the vehicle body posture changes due to external factors such as road surface conditions, the variable damping force shock absorber is controlled to a low level when the excitation direction is away from the neutral position. Since the damping force is configured to control the variable damping force shock absorber to a high damping force when the damping direction is toward the neutral position, there is no change in the vehicle body posture due to internal factors.
When changes in vehicle body posture occur due to external factors, the allocation effect can be effectively exerted to improve ride comfort.Moreover, the vehicle body posture change due to internal factors caused by operator operations can also be improved. The effect is that both posture stability and maneuverability can be improved.

[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 a schematic configuration of this invention, and FIG. 3 is a sectional view showing an example of a variable damping force shock absorber that can be applied to this invention. Fig. 4 is a characteristic curve diagram showing its attenuation and force holding ability, Fig. 5 is a block diagram showing an example of the displacement amount detection means, Figs. is a block diagram showing an embodiment of this invention,
FIG. 8 is a sectional view showing the embodiment, FIG. 11 is a graph showing the relationship between the transmission force and output voltage, and FIG. 12 is a graph showing the output voltage waveform when overcoming unevenness on the road surface. 1a to 1d...Wheels, 2...Vehicle body, 4
a to 4d... variable damping force shock absorber,
5... Cylinder tube, 6... Piston, 7... Piston rod, 10a to 10d
...'1ift solenoid, 11...
・Plunger, 21... Damping force selection switch,
22... Vehicle speed sensor, 23... Old steering angle sensor, 24... Throttle opening sensor, 25...
...Brake switch, 26a-26d...
・Relative displacement detection means, 28...Detection coil, 2
9...LC oscillator, 30...Frequency-
Voltage conversion circuit, 31...control device, 32...
...Microcomputer, 34...Multiplexer, 35...A/D converter, 36a-3
6d...drive transistor, 42...
Piezoelectric element.

Claims (1)

[Claims] The damping force of a variable damping force shock absorber that is interposed between the sprung mass and the unsprung mass of the vehicle and whose damping force can be changed by inputting a control signal is adjusted according to the relative displacement between the sprung mass and the sprung mass. In the shock absorber control device to be controlled, a relative displacement detection means for detecting a relative displacement between the sprung mass and the sprung mass, a vehicle body posture change detection means for detecting a change in vehicle body posture due to internal factors of the vehicle, and the relative displacement detection means a direction determining means for determining whether a change in relative displacement is in a direction away from the neutral position or in a damping direction based on a detected value by the means; and a direction determining means for determining whether a change in relative displacement is in a direction away from the neutral position or in a damping direction; outputting a control signal for controlling the variable damping force shock absorber to a high damping force only when the determination result of the direction determining means is in a direction away from the neutral position, and the vehicle body posture change detecting means control for outputting a control signal for controlling the variable damping force shock absorber to a high damping force only when the detection result of the direction determining means indicates a direction toward a neutral position, when the detection result is a state that causes a change in the vehicle body posture; A shock absorber control device comprising means.