JPS62265012A - Shock absorber control device - Google Patents

Abstract

PURPOSE:To improve driving comfortableness, by changing a damping force to a small value when the vertical movement of a body changes in a direction apart from a neutral body height after a control means changes the damping force. CONSTITUTION:A control means M3 issues a command to a damping force changing means M2 for changing a damping force to a large value at a prescribed timing while a vertical movement of a body sensed by a body vertical movement sensing means M1 changes in a direction of a neutral body height. On the other hand, when the vertical movement of the body changes in a direction apart from the neutral body height after the damping force has been changed, a return means issues a command to the damping force changing means M2 for changing the damping force to a smaller value. As a result, when vibration is caused in the body, the body can be returned to the neutral body height promptly. After that, when vibration is newly caused by any change in external forces, shock absorbing operation is effected for improving driving comfortableness.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to a shock absorber control device that changes damping force according to the period of vibration applied to a vehicle.

[Prior Art] Depending on the vehicle posture or the condition of the road surface on which the vehicle is traveling,
2. Description of the Related Art Conventionally, devices have been developed that control changes in the damping force of a shock absorber provided between a wheel and a vehicle body.

Regarding the vehicle attitude, there is a control device that controls the occurrence of skid, dive, roll, etc. by increasing the damping force of a shock absorber during sudden starts, sudden braking, slalom, etc., for example.

In addition, when driving on good roads, the damping force of the shock absorber is changed to a larger value to improve maneuverability and stability.
There is also a device that changes the damping force of the shock absorber to a medium value when driving on a rough road to maintain a good ride comfort and at the same time perform control to suppress vibrations.

For example, the state of the vehicle body or road surface is detected by a sensor, and the detection output of this sensor is input to a computer, and the effective volume of the surge tank and the gap between the surge tank and the air spring are determined based on commands from the computer. By changing at least one of the aperture amount of the throttle installed in the diaphragm or the damping force of the shock absorber, the characteristics of the air 1 suspension device can be changed depending on the vehicle and road surface conditions. "Suspension device" (Japanese Patent Application Laid-Open No. 59-23
712@publication) etc. have been proposed.

[Problems to be Solved by the Invention] This conventional shock absorber control device has the following problems. That is, (1) When the change in vehicle height exceeds a predetermined value, the damping force of the shock absorber is changed in order to damp the vibration without distinguishing between sprung vibration and unsprung vibration.

However, it is mainly the sprung vibrations that affect ride comfort. However, no control has been performed to change the damping force of the shock absorber in response to the period of the sprung mass vibration. Therefore, for example, the damping force may be uniformly maintained at a large value over several cycles of vibration, and there is a problem in that the damping force is not necessarily changed at an appropriate time.

(2) In addition, simply changing the damping force to a larger value for the purpose of convergence when the amplitude of the sprung mass vibration exceeds a predetermined value will not be effective for the occupants if, for example, vibrations due to external force occur again immediately after that. There was also the problem that unpleasant shocks were not absorbed, leading to a decrease in ride comfort.

An object of the present invention is to provide a shock absorber control device that changes the damping force according to the period of sprung vibration and also changes the damping force so as to absorb shock even when external force changes.

Structure of the Invention Means for Solving Problem F] The present invention, which has been made to solve the above problems, as illustrated in FIG. a detecting means M1; a damping force changing means M2 for changing the damping force of a shock absorber disposed between the wheels and the vehicle body in accordance with an external command; and a first vehicle height detected by the vehicle height detecting means M1. After a predetermined time set to less than half a period of the sprung mass vibration has elapsed since the predetermined value of The damping force changing means M2 issues a command to change the force to a larger value.
a control means M3 that outputs an output to the vehicle; and after the damping force is changed by the control means M3, if the vehicle height detected by the vehicle height detection means M1 changes in a direction away from the neutral vehicle height, the damping force is changed to a smaller value. The present invention is characterized by a shock absorber control device comprising: a return means M4 that outputs a command to change the damping force to the damping force change means M2; The vehicle height detection means M1 detects the distance between the wheels and the vehicle body as the vehicle height. For example, the displacement of the υ suspension arm with respect to the vehicle body may be converted into a rotation amount, and the rotation amount may be detected by a potentiometer and output as an analog signal. Further, for example, the rotation amount may be detected by a well-known rotary encoder and output as a digital signal.

The damping force changing means M2 changes the damping force of the shock absorber. For example, the damping force may be changed in two stages by opening and closing an orifice through which hydraulic oil of the shock absorber flows. Further, for example, by changing the diameter of the orifice, the damping force can be changed in multiple stages or in a continuous manner.

The control means M3 is determined according to the predetermined time and the first predetermined value after a predetermined time set to less than half the period of the sprung mass vibration has elapsed since the vehicle height exceeded the first predetermined value. If the damping force is larger than the second predetermined value, a command to change the damping force to a larger value is output. For example, a change in vehicle height due to sprung mass vibration is determined, and if the sprung mass vibration has a large amplitude that cannot be easily converged without changing the damping force, a command is issued to change the damping force to a larger value. It can be configured to output .

The return means M4 outputs a command to change the damping force to a smaller value when the vehicle height changes in a direction away from the neutral vehicle height after the damping force is changed by the control means M3.

For example, if sprung mass vibration converges once due to a change in damping force, and new sprung mass vibration or unsprung mass vibration occurs due to a change in external force, a command to change the damping force to a smaller value may be output. Can be configured.

The control means M3 and the return means M4 can also be realized, for example, as independent discrete logic circuits. For example, in addition to the well-known CPU, ROM,
It may be configured as a logic operation circuit together with a RAM and other peripheral circuit elements, and may project both means M3 and M4 according to a predetermined processing procedure.

[Function] As illustrated in FIG. 1, the shock absorber control device of the present invention, from the time when the vehicle height detected by the vehicle height detection means M1 exceeds the first predetermined value, reduces the sprung mass vibration to less than half a period. If the predetermined value is larger than the second predetermined value determined according to the predetermined time and the first predetermined value after the predetermined time has elapsed, the control means M3 issues a command to change the damping force to a larger value. On the other hand, if the vehicle height detected by the vehicle height detection means M1 changes in a direction away from the neutral vehicle height after the damping force is changed by the control means M3, the return means M4 changes the damping force. It works to output a command to change the damping force to a smaller value to the damping force changing means M2.

In other words, when a sprung mass vibration with an amplitude exceeding the first predetermined value occurs, the damping force is applied at a predetermined time until the vehicle height returns to the neutral vehicle height due to the oscillation occurring within a half cycle of the sprung mass vibration. Change to a large value to suppress vehicle height changes,
When the vehicle height changes again away from the neutral vehicle height due to a subsequent change in external force, control is performed to change the damping force to a smaller value to absorb the impact caused by the change in external force.

Therefore, the shock absorber control device of the present invention quickly returns the vehicle height to the neutral vehicle height when sprung mass vibration occurs such that the vehicle height exceeds the first predetermined value, and then new vibrations occur due to external force changes. Sometimes it works to absorb the shock. The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings.

FIG. 2 shows a system configuration of a shock absorber control device according to a first embodiment of the present invention.

The left and right front wheel height sensors HIL and HIR and the rear wheel height sensor 12G detect the distance between each suspension arm and the vehicle body, each of which follows the vertical movement of the wheel. Short cylindrical bodies ILa, IR of vehicle height sensors HIL, H1R, H2C
a, 2Ca are fixed to the vehicle body side, and the main bodies ILa, IRa
, 2Ca have links ILb and 1R approximately perpendicular to their central axes.
b, 2Cb are connected. The link ILb, IRb
.

The other end side of 2Cb is a turnbuckle ILc, IRC, 2
It is rotatably connected to one end of the CG, and the other ends of the turnbuckles ILc, IRc, and 2Cc are rotatably connected to a part of each suspension arm. In addition, each vehicle height sensor HIL, HIR.

The H2C has a built-in well-known rotary encoder, which is connected to an electronic control device 4, which will be described later, as shown in FIG. 3(A), and outputs the displacement of the vehicle height as a digital signal. Moreover, as the vehicle height sensors HIL, HIR, and H2G, those incorporating well-known potentiometers may be used.

In this case, as shown in FIG. 3(B), it is necessary to configure the analog signal to be converted into a digital signal by an A/D converter 4fl and manually input it to the electronic control device 4, which will be described later.

Returning to Figure 2 again, shock absorber SIL.

The SIR, 82m, and S2R are each installed in parallel with a suspension device (not shown) between the four suspension arms of the left and right front and rear wheels and the vehicle body.

Damping force change actuator A1L, ΔIR, A2L, A
2R is each of the above shock absorbers SIL, SIR, S
It is arranged in 2L and S2R.

The signals detected by the vehicle height sensors 11, 1-11R, and H2C are input to an electronic control unit (hereinafter simply referred to as CU) 4, and the FCU 4 controls the damping force changing actuators A'I L and AIR described above. , A2L, and A2R.

Shock absorber SIL, SIR, S2L.

Since the structure of S2R is all the same, shock absorber S
This will be explained using IL as an example. As shown in FIG. 4 (A), the shock absorber 81m has a hollow screw rod 21 inside the outer cylinder 20 and the outer cylinder 20 (which can be moved freely).
It has a piston 22 that is aligned with +X. piston rod 21
A control rod 23 is loosely fitted inside, and the control rod 23 is supported by a guide 23a fixed to the screws 1 to 21. The control rod 23 is a damping force changing actuator AIL which will be described later.
The rotary valve 24, which is fixed to the control rod 23, is rotated by the control rod 23, and the orifice 25 is opened and closed. The plate valves 26 and 27 each have a nut 28
．． 29 is fixed to the piston 22.

The piston rod 21 and the control rod 23 are the fourth
If the positional relationship is as shown in figure (B), that is,
When the control rod 23 is at a position making an angle of 90' with respect to the front direction indicated by the arrow [, the above-mentioned orifice 25 is in a communicating state. Also, on the line side, the fourth
As shown in Figure (A), the plate valve 26 opens and the passage 30a communicates with each other.On the other hand, on the extension side, as shown in Figure 4(C), the valves 1 to 27 open and the passage 30b communicates with each other. For this reason, the hydraulic oil flows through lines 1, 4, and Fig. 4 (
The orifice 25 and the passage 3 as shown by the arrow in A)
0a, and on the expansion side, it flows through both the orifice 25 and the passage 30b as shown by the arrow V in FIG. The damping force is set to a small value.

On the other hand, the piston rod 21 and the control rod 2
3 are in the positional relationship as shown in FIG. 5(B),
That is, the front direction [indicated by the arrow] and the control [
(2) When the rad 23 is in a parallel position, the orifice 25 described above is in a blocked state. Therefore, on the line side, the hydraulic oil flows only through the passage 30a as shown by the arrow U in Fig. 5 (A>), and on the extension side, it flows only through the passage 3ob as shown by the arrow V in Fig. 5 (C). Since the throttling resistance of the hydraulic oil is large, the damping force of the shock absorber 811- is set to a large value.

Damping force change actuator AI L, AIR, A2L,
Since the structure of A2R is also completely the same, we will use AlL as an example.
This will be explained based on the diagram. Damping force change actuator AI
L is the DC motor 30, and L is taken from the DC motor 30 (=l
A shifted pinion gear 31 and a sector gear 32 that meshes with the pinion gear 31 are small. The above sector gear 32
The previously described control rod 23 is fixed to the center of the .

When the direct current controller 30 is rotated forward or reverse under the drive control of the ECtJ4, which will be described later, the control rod 23 is rotated forward or reverse to open and close the orifice 25 described above, thereby changing the damping force of the shock absorber 511-. Note that the rotation of the control rod 23 is limited to within 90' by a lever 34 provided on the central shaft 33 of the sector gear 32 and stoppers 35 and 36 disposed at positions 90' apart from each other.

Next, the configuration of the FCU 4 will be explained based on FIG. 7. The ECU 4 inputs and calculates each data detected by each of the sensors described above according to a control program, and also performs processing for controlling the various devices described above. It is configured as a logic operation circuit centered around RAM 4G, which temporarily stores various data input to the ROM 4b1 FCU 4 and data necessary for calculation control, and is connected to the input boat 4f and output port 4q via the Mosin bus 4. and performs input/output with the outside.

The above-mentioned middle and high school senior year-111, l-11R.

The detection signal of H2C is sent to CPLJ4 via input port 4f.
input to a. In addition, E CLJ 4 is equipped with the damping force changing actuator AIL, AIR, A2L, A2.
Equipped with R drive circuits 4h, 4i, 4j, 4k, CPU4
a connects each of the above drive circuits 4h and 4i via the output port 4q.
, 4j, and 4k. Note that the ECU 4 includes a self-running timer 4m that generates an interrupt to the CPU 4a when a preset predetermined time has elapsed.

Next, the shock absorber control process executed by the above-mentioned ECU 4 will be explained based on the flowchart of FIG. 8. This shock absorber control processing is ECt
Executed when J4 is started.

In step 100, initialization processing is performed.

At the same time, the memory is cleared, the timer is reset, etc., and the value O is set as an initial value in the register that stores the displacement of the vehicle height A. Next, the process proceeds to step 110, where processing is performed to change the damping force to a smaller value. That is, the damping force changing actuators A1 L and AIR described above
, A2L, and A2R, the DC motor 30 rotates counterclockwise (CCW), and the control rod 2
3 rotates to communicate the orifice 25 of the rotary valve 24.

In the following step 120, a process of detecting the vehicle height A is performed. Here, the vehicle height A is the left front wheel vehicle height sensor HIL,
Among the output signals of HIR or rear wheel height sensor H2C,
The largest one may be detected. Further, the left and right average values may be used, or the height may be detected from a predetermined specific vehicle height sensor.

Next, the process proceeds to step 130, where it is determined whether the absolute value of the vehicle height A detected in step 120 exceeds the first vehicle height displacement setting value A1. Note that the first vehicle height displacement setting value A1 is 30 [mm 16-m] in this embodiment. The absolute value of vehicle height A is the first vehicle height displacement setting value A1
If it is determined that the vehicle height A is below, the process returns to step 120 and the vehicle height A is detected again. On the other hand, if it is determined that the absolute value of the vehicle height A exceeds the first vehicle height displacement setting value A1, it is assumed that a large change has occurred in the vehicle attitude, and the process proceeds to step 140.

In step 140, delay processing is performed. In other words,
After a delay time td has elapsed from the time when the absolute value of the vehicle height displacement is determined to be around the first vehicle height displacement set value A1, a predetermined delay 114 tb is applied in order to actually change the damping force to a larger value. A process of waiting until the time has elapsed is performed. Here, the delay time td is calculated as shown in the following equation (1).

td = tb + ta - (1) However, tb...delay time ↑a...damping force switching time delay time td is a predetermined time set to less than half the period of the sprung mass vibration. It varies depending on the value of the high displacement setting value A1, etc. The delay time td is 20 to 500 [m5e
c] range is preferable, but for normal vehicles it is 300
A value of about [m5ec] is good. In this example, since the damping force switching time ta is 60 [m5ec], the delay time tb is 240 [m5ec], and the delay time td is
was set to 300 [m5ecl.

Timing is performed by the timer 4m, and when the delay time tb has elapsed, the process proceeds to step 150. At step 150, the same process as step 120 for detecting the vehicle height A is performed again. Next, proceed to step]60, and proceed to step 15 above.
The absolute value of the vehicle height A detected at 0 is the second vehicle height displacement setting value A2
A determination is made as to whether or not it exceeds . In this embodiment, the second vehicle height displacement setting value A2 is 30 [mm], which is the same as the first vehicle height displacement setting value A1. If it is determined that the absolute value of the vehicle ^A is less than or equal to the second vehicle height displacement setting value A2, the vehicle height displacement is determined to be due to unsprung vibration, and the process proceeds to step 120.
The vehicle height A is detected again. On the other hand, vehicle height A
If it is determined that the absolute value of is greater than the second vehicle height displacement setting value A2, it is determined that the vehicle height displacement is due to sprung vibration, and the process proceeds to step 170. In step 170, processing is performed to change the damping force to a larger value. In other words,
The damping force actuator AIL mentioned above.

AIR, A2L, and A2R are started to be energized, the DC motor 30 rotates in the CW direction, the control rod 23 rotates, and the orifice 25 of the rotary valve 24 is shut off.

Next, the process proceeds to step 180, where a process of detecting the vehicle height A is performed.

In the following step 190, it is determined whether the absolute value of the vehicle height A detected in the step 180 exceeds the vehicle height neutral setting value A3. In this embodiment, the vehicle height neutral setting value A3 is 5[
It is rrlml. The absolute value of vehicle height △ is vehicle height neutral setting value A
If it is determined that the vehicle height is 3 or more, it is assumed that the vehicle height has not yet returned to near the neutral vehicle height, and the process continues at step 20.
Go to 0.

In step 200, it is determined whether the difference between the absolute value of the current vehicle height A and the absolute value of the previously detected and stored vehicle height A([)-1) is less than the determination value 8. 19 constants are performed. In this example, the judgment value B is O [mm]
It is. The absolute value of vehicle height A and the previously detected vehicle height A (
If it is determined that the difference from the absolute value of n-1> is less than the determination value 8, it is assumed that the vehicle height is returning to the neutral vehicle height, and the process returns to step 180, where the vehicle height A is detected.

On the other hand, if it is determined in step 190 that the absolute value of the vehicle height A is less than the vehicle height neutral setting value A3, it is assumed that the vehicle height has returned to near the neutral vehicle height, and the process returns to step 110 to reduce the damping force. Processing to change it to a value is performed. Also, in step 200, the absolute value to the vehicle height and the previously detected vehicle height A are calculated.
If it is determined that the difference between the absolute value of (nt) and the absolute value of
In order to absorb the impact, processing is performed to change the damping force to a smaller value. Thereafter, steps 110 to 190 described above
(or 200) are repeatedly executed.

Next, an m-20= example of the above-mentioned shock absorber control will be explained based on the timing chart shown in FIG. When a wheel rides on a protrusion on the road surface, causing unsprung vibration, the vehicle height changes significantly, moving away from the neutral vehicle height, and the vibrations repeat at a rapid frequency. Due to such unsprung vibration, the vehicle height Δ may change and exceed the first vehicle height displacement set value Δ1, and this time is T1. Then, at the above time -
At time T2 after the lag time tb has elapsed from 1, it is determined whether the vehicle height A goes -L times around the second vehicle height displacement setting vessel A2. The synchronization is short, and at time T2, the vehicle height A is the second vehicle height displacement setting value A.
It is often smaller than 2. Therefore, the damping force is kept at a small value to improve ride comfort.

Furthermore, when a wheel rides on an obstacle on the road surface or when the vehicle posture suddenly changes during driving, the vehicle height A changes significantly and deviates from the neutral vehicle height during sprung mass vibration. The time when the vehicle height A changes in this way and exceeds the first vehicle height displacement set value Δ1 is T3. After time T3, vehicle height A
The displacement further increases by = 21- and after reaching the maximum value, it changes to the neutral vehicle height in the direction of C due to swinging back. Delay time tb from the above time T3
At time T4 after the elapse of time, it is determined whether the vehicle height A exceeds the second vehicle height displacement set value A2. During the sprung mass vibration, the vibration synchronization is long as shown in the figure, and the vehicle height A is larger than the second vehicle height displacement setting value A2 even at time T4. For this reason,
Damping force change actuator All, AIR, A2L, A
Application of drive current is started to 2R. At time T5, after the damping force switching time ta has elapsed from the same time T4, the damping forces of the shock absorbers 811.31R, 32m, and S2R are changed to larger values. Note that the same time T5 is the time T when the absolute value of the displacement of the vehicle height A exceeds the first vehicle height displacement setting value A1.
This is the time when the delay time td has elapsed from 3.

If the damping force remains at a small value, the displacement of the vehicle height A will change greatly as shown by the broken line, but since the damping force was changed to a large value at time - [5, the displacement of the vehicle height A will change as shown by the solid line. Attenuates as shown. However, due to a new external force, the vehicle height A leaves the neutral vehicle height again. As a result, t, 1 time T7
At , the difference between the absolute value of the vehicle height A and the absolute value of the previous vehicle height (vehicle height at time 1-6) A(nt) exceeds the determination value B.

Therefore, the vehicle height is determined to be far from the neutral vehicle height,
At the same time T7, the damping force changing actuator
1, AIR, A2L, and A2H are started, and at time T8 after the elapse of the damping force switching time ta, the damping force is changed to a small value, and the cylindrical portion due to the new external force is absorbed.

In this example, the front wheel height is J-H1l.

HIR and rear wheel height sensor 9-H2C and ECU4 and the E
Processing performed by CLJ4 (step 120.15
0,180> functions as vehicle height detection means M1, shock absorbers SIL, SIR, S2L, S2R and damping force changing actuator AIL.

AIR, A2L, and Δ2R correspond to the damping force changing means M2. Also, among the processes executed by the ECLJ4 and the ECU4 (steps 130, 140.160.1
70) as the control means M3, (steps 200, 11
0> functions as the return means M4.

As explained above, in the first embodiment, if the vehicle height A is larger than the second vehicle height displacement setting value A2 after the delay time tb has elapsed from the time when the vehicle height A exceeded the first vehicle height displacement setting value A1, After the delay time td has elapsed, the damping force is changed to a larger value,
Thereafter, when the vehicle height A changes again in a direction away from the neutral vehicle height, the damping force is changed to a smaller value. Therefore, once the sprung mass vibration has converged, if the vehicle height A deviates from the neutral vehicle height due to a new external force, the damping force is changed to a small value to absorb the cylindrical portion caused by the external force, resulting in a comfortable ride. It is possible to improve the

In addition, it detects only changes in vehicle height caused by sprung vibrations,
Since the damping force is changed to a large value, it is possible to suppress the vibration within a half period of the sprung mass vibration and quickly return the vehicle height to the neutral vehicle height.

Roughly speaking, since the vehicle height displacement due to sprung vibration that affects ride comfort is detected and the damping force is changed to a larger value after the delay time td has elapsed, the damping force can be switched at a suitable time to improve ride comfort. It becomes possible.

In addition, unnecessary changes in damping force are prevented, and shock absorbers SIL, SIR, S2L, S2R, and damping force changing actuators AIL, AIR.

The durability of A2L and A2R can be improved.

Next, a second embodiment of the present invention will be described. Second example and first example
The difference from the embodiment lies in the shock absorber control processing executed by the ECU 4km, and the other configurations are completely the same. FIG. 10 is a flowchart showing the shock absorber control process of the second embodiment, in which a reverse rotation step 210 of step 200 is added to the flowchart of FIG. 8 shown in the first embodiment.

That is, when determining whether the vehicle height is far from neutral, the differences between the two previously detected vehicle heights and the current vehicle height are each compared with a determination value B. In step 200, it is determined whether the difference between the absolute value of the current vehicle height and the absolute value of the vehicle height A(nt) detected before 120 [m5ec] is less than the determination value 8.

Further, in step 210, the absolute value of the current vehicle height A and 4
It is determined whether the difference from the absolute value of the vehicle height A (n-Kt) detected before 0 [m5ec] is less than the determination value 8. If a preliminary decision is made in both steps 200 and 210, it is assumed that the vehicle height is returning to the neutral vehicle height, and the process returns to step 180, where the vehicle height is detected again. On the other hand, if a negative determination is made in either step 200 or 210, it is assumed that the vehicle height is changing away from the neutral vehicle height, and the process returns to step 110, where the damping force is changed to a smaller value. .

Next, an example of the above control will be explained with reference to the timing chart of FIG. 11. Due to the occurrence of sprung mass vibration, the vehicle height exceeds the first vehicle height displacement setting value A1 at time 711, and the vehicle height is still larger than the second vehicle height displacement setting value A2 at time T12 after the delay time tb has elapsed. Therefore, time − “1
In step 3, the damping force is changed to a large value (step 1
20,130.140,150,160.170>.

Next, when sprung mass vibration occurs again due to a new external force, the vehicle height moves away from the neutral vehicle height while changing in a relatively long period, as shown by the solid line in the figure. At this time, the absolute value of the vehicle height A at time T19 and 120 [m
Vehicle height A(n-t
) is greater than the judgment value B (step 20
0). Therefore, assuming that the vehicle height has changed in a direction away from the neutral vehicle height, the damping force is changed to a smaller value at time -120 (step 110).

On the other hand, when unsprung vibration is caused by a new external force, the vehicle height moves away from the neutral vehicle height while changing in a relatively short period as shown by the broken line in the figure. At this time, the absolute value of the vehicle height a at time T16 and 120 [m5ec
The difference from the absolute value of the vehicle height a (nt) detected at time T14 before l is less than the judgment value 8 (step 200
). This is because the period of the unsprung vibration is λ0, and the two times are 14.0 and 120 [m5eG] apart, which is a relatively long time. This is because the amplitude of the pull at T16 is approximately the same value. In this way, simply comparing the current vehicle height a with the vehicle height a(nt) before time 120 [m5ec] It is not possible to detect the development in which the vehicle height separates from the neutral vehicle height due to unsprung vibration.Therefore, at time 16 (J), the absolute value of vehicle height a and the time 40 [m5ec] before that time T'16 are determined. The difference between the absolute value of the vehicle height a(n-Kt) detected in 15 below is compared with the judgment value B (step 210).Then, the -V difference exceeds the judgment value B, so the vehicle height is a neutral vehicle. As the damping force moves away from the high value, the damping force is changed to a small value at time 17 (
Step 110). In this way, the vehicle height at the current time T16 and the relatively short time/10 [m5
Comparing the vehicle height with the vehicle height before ECL, it is possible to detect a phenomenon in which the vehicle height deviates from the neutral vehicle height due to unsprung vibration with a relatively short period.

In the second embodiment, the process executed by ECtJ4 (steps 200, 210, and 110) functions as return means M1.

As explained above, in the second embodiment, the absolute value of the current vehicle height A, 120 [m5ec] J'3 and 40 [ms e
c ] Previously detected vehicle height A(nt) and A
When at least one of the differences from the absolute value of (n-Kt) exceeds the judgment value B, the damping force is changed to a smaller value, assuming that the vehicle height is changing away from the neutral vehicle height. ing. Therefore, in addition to the effects of the first embodiment already described, it is possible to accurately detect the case where the vehicle height deviates from the neutral vehicle height due to not only sprung vibration but also unsprung vibration, and change the damping force to a smaller value. Therefore, shocks caused by new external forces can be reliably absorbed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. be.

Effects of the Invention As described in detail above, the shock absorber control device of the present invention detects that the vehicle height detected by the vehicle height detection means is larger than the second predetermined value after a predetermined time has elapsed from the time when the vehicle height detected by the vehicle height detection means exceeds the first predetermined value. In this case, the control means outputs a command to change the damping force to a larger value to the damping force changing means, and if the vehicle height changes in a direction away from the neutral vehicle height after the damping force change, the return means outputs a command to change the damping force to a larger value. It is configured to output a command to change the force to a smaller value to the damping force changing means. For this reason, even if the damping force is once changed to a larger value for the purpose of convergence of spring tooth vibration, when new vibration occurs due to a change in external force, the damping force is changed to a smaller value, so the shock absorption This has the excellent effect of making it easier and improving riding comfort.

Further, the damping force of the shock absorber can be controlled to be changed at a suitable time in accordance with the period of sprung mass vibration that affects riding comfort.

Furthermore, since the sprung mass vibration is converged in a short time, within a half cycle of the sprung mass vibration, the vehicle height can be quickly returned to the neutral vehicle height.

In addition, since the damping force is changed to a larger value only when sprung vibrations that are closely related to ride comfort occur, unnecessary damping force changes in response to unsprung vibrations are eliminated, improving the durability of the damping force changing means. do.

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, Fig. 2 is a system configuration diagram of the first embodiment of the present invention, and Fig. 3 (
A) and (B) are block diagrams similarly showing the vehicle height sensor and its input circuit, and FIG. 4 (A). (B) and (C) are also explanatory diagrams when the damping force of the shock absorber is set to a small value, and Fig. 5 (
A>, (B), and (C) are also explanatory diagrams when the damping force of the shock absorber is set to a large value, and Figure 6 is a perspective view of the damping force changing actuator 1 of the shock absorber. 7 is a block diagram for explaining the configuration of the electronic control unit (ECU), FIG. 8 is a flowchart showing the control, FIG. 9 is a timing chart, and FIG. 10 is the invention of the present invention. A flowchart showing the control of the second embodiment, and FIG. 11 is a timing chart thereof as well. Ml...Vehicle height detection means M2...Damping force changing means M3...Control means M4...Returning means Hll, HIR...Front wheel height sensor 1-120...Rear wheel height sensor SIL , SIR, 82m, S2R... Shock absorber AIL, AIR, A2L, A2R... Damping force changing actuator 4... Electronic control unit (ECU) 4a... CPU

Claims (1)

[Scope of Claims] 1. Vehicle height detection means that detects the distance between the wheels and the vehicle body as the vehicle height, and damping that changes the damping force of a shock absorber disposed between the wheels and the vehicle body in accordance with an external command. force changing means, and after a predetermined time set to less than half a period of the sprung mass vibration from the time when the vehicle height detected by the vehicle height detection means exceeds the first predetermined value, the predetermined time and the first a control means for outputting a command to change the damping force to a larger value when the damping force is larger than a second predetermined value determined according to the predetermined value; and after the damping force is changed by the control means; a return means for outputting a command to change the damping force to a smaller value to the damping force changing means when the vehicle height detected by the vehicle height detecting means changes in a direction away from the neutral vehicle height; A shock absorber control device characterized by: