JPS638010A - Shock absorber control device - Google Patents

Abstract

PURPOSE:To improve a preventing force for low frequency vibration, by a method wherein, in a title device for a vehicle, when an accumulating valve of a change in acceleration exceeds a given value for a specified time commencing with a time when vertical acceleration exceeds a given value, a damping force is increased. CONSTITUTION:Vertical acceleration is detected by an acceleration detector M1, and is inputted to a control means M3. The control means M3 accumulates a change in vertical acceleration M1 during a given time commencing with a time when the acceleration M1 exceeds a given acceleration to determine a decision value. When the decision value exceeds a given value, an instruction is outputted to a damping force varying means M2 so that a damping force is increased. Output of the instruction causes variation of the damping force of a shock absorber into a high value. This constitution enables accurate detection of vibration of relatively low frequency and effective prevention of production of the low frequency vibration.

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 is effective in suppressing vehicle body imaging.

[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 increases the damping force of a shock absorber to a large value during a sudden start, sudden braking, slalom, etc. to suppress the occurrence of skid, dia, roll, etc.

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 rough roads to maintain a good ride comfort and at the same time performs control to suppress vibrations.

As the above-mentioned device, for example, "automobile suspension system"
(Japanese Unexamined Patent Publication No. 60-47709) and the like have been proposed. That is, the duration during which the acceleration of photographing is equal to or greater than a predetermined value is measured, and only when this duration continues for a predetermined determination time or more, the damping force is increased or the spring constant is increased.

[Problems to be Solved by the Invention] Incidentally, the acceleration while the vehicle is running changes as shown in FIG. 9, for example. In other words, the acceleration detection waveform is a composite wave of a low frequency waveform and a high frequency waveform. Here, in general, the low frequency waveform corresponds to the spring main vibration, while
The high frequency waveform is due to the effect of unsprung imaging.

Since the acceleration detection waveform shown in FIG. 9 includes a low frequency waveform that is equal to or higher than the determination value over a long period of time from time t1 to time t13, the damping force of the shock absorber must be increased. However, because it temporarily falls below the judgment value due to the influence of the high frequency component mentioned above, the duration of the judgment value or more is shortened from time t1 to time t2, and it does not continue for more than the judgment time, so the damping force cannot be switched. . As described above, it is extremely difficult to measure the duration during which the acceleration is equal to or greater than the determination value and to accurately grasp the vibration state of the vehicle body based on the length of the duration, due to the influence of high frequency components. Therefore, in the control based on the conditions as in the prior art, there is a problem in that the damping force cannot necessarily be switched to a larger value when it is necessary.

Furthermore, as described above, the damping force is not always appropriately switched for relatively low-frequency vibrations, so there is a problem in that it is difficult to suppress vibrations such as pitching and bouncing of the vehicle body.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shock absorber control device that accurately detects and appropriately suppresses relatively low-frequency imaging occurring in a vehicle body.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to solve the above problems, includes an acceleration detection means M1 for detecting vertical acceleration of a vehicle body, as illustrated in FIG.
and a damping force changing means M2 that changes the damping force of a shock absorber disposed between the wheels and the vehicle body according to an external command; and when the acceleration detected by the acceleration detecting means M1 exceeds a predetermined acceleration. control means M3 for outputting a command to change the damping force to a larger value to the damping force changing means M1 when a judgment value that is the accumulation of changes in acceleration from 1 to 3 after a predetermined time is greater than or equal to a predetermined value; The gist of this invention is a shock absorber control device characterized by:

The acceleration detection means M1 detects the acceleration of the vehicle body in the vertical direction. For example, the vertical acceleration of the front and rear parts of the vehicle body may be detected independently. For example, this can be achieved using various types of gyros. Further, for example, it may be configured by a servo acceleration sensor. With this configuration, detection accuracy and stability can be improved.

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 outputs a command to change the damping force to a larger value when a judgment value obtained by accumulating changes in acceleration from the time when the acceleration exceeds a predetermined acceleration until after a predetermined period of time is a predetermined value or more. It is something. Here, the determination value may be, for example, an added value of acceleration over the above-mentioned predetermined time,
Alternatively, for example, it may be an average value of acceleration over the predetermined time period. For example, the control means M3 issues a command to change the damping force on the front wheel side to a larger value when the judgment value based on the acceleration of the front part is above a predetermined value, and on the other hand, when the judgment value based on the acceleration of the rear part is above a predetermined value. In this case, the configuration can be such that a command for changing the damping force on the rear wheel side to a larger value is output independently. With this configuration, even if the front and rear parts of the vehicle have different vibration characteristics, vibrations can be effectively suppressed.

The control means M3 can also be realized, for example, as an independent discrete logic circuit. Further, for example, the control means M3 may be configured as a logic operation circuit together with a well-known CPU, ROM, RAM, and other peripheral circuit elements, and implement the control means M3 according to a predetermined processing procedure.

[Function] As illustrated in FIG. 1, the shock absorber control device of the present invention, as illustrated in FIG. When the judgment value obtained by accumulating the changes is greater than or equal to a predetermined value, the control means M3 operates to output a command to change the damping force to a larger value to the damping force changing means M2.

That is, since the influence of high frequency components is reduced by the accumulation of changes in acceleration, it is possible to detect relatively low frequency vibrations and change the damping force to a large value.

Therefore, the shock absorber control device of the present invention works to suppress relatively low frequency sprung motion.

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 the system configuration of a shock absorber control device that is an embodiment of the present invention.

The shock absorber control device 1 includes a front acceleration sensor 2
, rear acceleration sensor 3, shock absorber S1L, S
1R, 32m, S2R, damping force change actuator A1
It is comprised of L, AI R, A2L, A2R, and an electronic control unit (hereinafter simply referred to as ECU) 4 that controls these.

Both of the acceleration sensors 2 and 3 are servo acceleration sensors, and the front acceleration sensor 2 is located at the front of the vehicle.
The rear acceleration sensor 3 detects the vertical acceleration of the rear part of the vehicle body.

Shock absorber S1L, S1R, S2L.

Each S2R is installed in parallel with a suspension device (not shown) between the suspension arms of the left and right front and rear wheels and the vehicle body.

Damping force change actuator A1L, A1R, A2L, A
2R is each of the above shock absorbers S1L, S1R, S
It is arranged in 2L and S2R.

The im detected by both acceleration sensors 2 and 3 above is ECU4
The ECU 4 drives and controls the damping force changing actuators A1L, AlR, A2L, and A2R.

Shock absorber S1L, S1R, 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. 3 (A>), the shock absorber 31L has a hollow piston rod 21 inside an outer cylinder 20 and a piston 22 that is movably fitted to the outside 120. Inside the piston rod 21 is a control rod. 23 is loosely fitted, and the control rod 23 is connected to the guide 2 fixed to the piston rod 21.
3a. Above control rod 2
3 is rotated by a damping force changing actuator A1L, which will be described later, to drive a white-tally pulp 24 fixed to the control rod 23, thereby opening and closing an orifice 25. Plate valves 26, 27 are each fixed to piston 22 by nuts 28,29.

The piston rod 21 and the control rod 23 are the third
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 arrow F, the above-mentioned orifice 25 is in a communicating state. Also, on the line side, there is a third
As shown in Figure (A>), the plate valve 26 opens and the passage 30a communicates.On the other hand, on the expansion side, as shown in Figure 3(C), the plate valve 27 opens and the passage 30b opens. Therefore, the hydraulic oil flows through the orifice 25 and passage 30a on the line side as shown by the arrow U in Figure 3 (A>), and flows through the orifice 25 and the passage 30a on the expansion side as shown by the arrow V in Figure 3 (C). The damping force of the shock absorber S11 is set to a small value because the hydraulic oil flows through both the paths 25 and 30b, and the throttling resistance of the hydraulic oil is small.

On the other hand, when the piston rod 21 and the control rod 23 are in the positional relationship as shown in FIG. 4(B), that is, when the front direction indicated by arrow F and the control rod 23 are in a parallel position, The previously described orifice 25 enters the blocked state. Therefore, on the line side, the hydraulic oil flows only through the passage 30a as shown by the arrow U in Fig. 4 (A>), and on the extension side, as shown by the arrow V in Fig. 4 (C), the hydraulic oil flows only through the passage 30a.
The damping force of the shock absorber S1L is set to a large value because the hydraulic oil flows only through the ob and the throttling resistance of the hydraulic oil is large.

Damping force change actuator A1L, A1R, A2L, A
Since the structure of 2R is also completely common, the fifth
This will be explained based on the diagram. Damping force change actuator AI
L includes a DC motor 30, a pinion gear 31 attached to the DC motor 30, and a sector gear 32 that meshes with the pinion gear 31. The aforementioned control rod 23 is fixed to the center of the sector gear 32.

When the DC motor 30 is rotated forward or reverse under the drive control of the ECU 4, 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 31L. In addition, sector gear 3
The lever 34 provided on the central shaft 33 of
The rotation of the control rod 23 is limited to within 90' by stops 35, 36 arranged at an angle of 90°.

Next, the configuration of the ECU 4 will be explained based on FIG. 6. The ECU 4 includes a CPU 4a that inputs and calculates each data detected by each of the sensors described above according to a control program, and performs processing for controlling the various devices described above, and the control program and initial data are stored in advance. It is configured as a logic operation circuit centered around ROM4b and RAM4C, which temporarily stores various data input to the ECU4 and data necessary for arithmetic control.
It is connected to an input port 4f and an output port 4q via a common bus 4e to perform input/output with the outside. The detection signals of both the acceleration sensors 2 and 3 mentioned above are sent to the A/D converter 4.
n, is input to the CPU 4a via the input port 4f.

The ECU 4 also operates the damping force changing actuator A described above.
1L, A1R, A2L, A2R drive circuits 4h, 41.
4j.

4k, and the CPU 4a outputs control signals to each of the drive circuits 4h, 4i, 4j, and 4k via an output port 4q. 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 front wheel shock absorber control process executed by the ECtJ4 will be explained based on the flowcharts shown in FIG. 7, and the rear wheel shock absorber control process executed by the above flowcharts shown in FIG.

The front wheel shock absorber control process is executed when the ECU 4 is activated. First, in step 100, a process of detecting front vertical acceleration Gf from the front acceleration sensor 2 is performed. In the following step 110, the above step 1
It is determined whether the absolute value of the front vertical acceleration Gf detected in step 00 is greater than or equal to the front acceleration reference value af, and if an affirmative determination is made, the process proceeds to step 120, whereas if a negative determination is not made, the above Return to step 100. Here, the value of the front acceleration reference value af is predetermined in consideration of the imaging characteristics of the front part of the vehicle, based on the value of the vertical acceleration that feels uncomfortable to the occupant. In step 120, which is executed when the absolute value of the front vertical acceleration Gf is greater than or equal to the front acceleration reference value af, a process is performed in which N front vertical accelerations are inputted every time. Here, for example, assuming that the frequency of imaging to be suppressed is 3 [H2] or less, the time t which is the sampling time is set to 0.008 [sec], and the number N is set to 10. Then, the time is 0.083 [m5e
C], the front vertical acceleration can be detected. In addition, time 0.083 [m5ec] is frequency 3
This corresponds to a half period of the commotion in [H2]. In the subsequent step 130, a process is performed to calculate the sum Vf of the N front vertical accelerations as shown in the following equation (1).

Next, the process proceeds to step 140, where it is determined whether the absolute value of the addition value Vf calculated in step 130 is greater than or equal to the front addition reference value bf. If the absolute value of the addition value Vf is greater than or equal to the front addition reference value bf, it is assumed that low-frequency imaging has occurred on the vehicle body, and the process proceeds to step 150, where the damping force of the front wheel shock absorbers SIL and S1R is increased to a large value. After the process of changing the value to 1 is performed, the process returns to step 120 described above.

On the other hand, if the absolute value of the addition value Vf is less than the front addition reference value bf, it is assumed that low frequency imaging has converged or has not occurred, and the process proceeds to step 160, where the front wheel shock absorber 81L.

After changing the damping force of S1R to a smaller value, the process returns to step 100. After that, the above steps 100 to 160
is executed repeatedly.

Next, the rear wheel shock absorber control process will be explained according to the flowchart shown in FIG. This rear wheel shock absorber control process is executed when the ECU 4 is activated. First, the rear vertical acceleration Qr is detected from the rear acceleration sensor 3 (step 200), and it is determined whether the absolute value of the rear vertical acceleration Gr is greater than or equal to the rear acceleration reference value ar (step 210). If an affirmative determination is made in step 210, step 220) inputs N rear vertical accelerations for each time, calculates the sum vr of the N rear vertical accelerations step 230), and calculates the sum vr of the N rear vertical accelerations.
It is determined whether the absolute value of r is greater than or equal to the rear addition reference value br (step 240). If an affirmative determination is made in step 240, the damping force of the rear wheel shock absorbers 32L and S2R is changed to a larger value in order to suppress vehicle body imaging in step 250>, and then the process returns to step 220. On the other hand, if a negative determination is made in step 240, the process proceeds to step 260, where the rear wheel shock absorber S2
Step 26: Change the damping force of L and S2R to a smaller value.
0), then return to step 200 above. Thereafter, steps 200 to 260 are repeatedly executed.

In this embodiment, the front acceleration sensor 2 and the rear acceleration sensor 3 serve as the acceleration detection means M1, and the shock absorbers S1L, SIR, S2L, and S2R and the damping force changing actuators A1L, A1R, A2L, and A2R serve as the damping force changing means. Each corresponds to M2. In addition, the ECU 4 and the processes executed by the ECU 4 (steps 110, 120,
130°140.150,210,220,230,2
40.250> functions as the control means M3.

As explained above, in this embodiment, the sum of N front vertical accelerations inputted every time from the time when the absolute value of the front vertical acceleration of the vehicle body becomes equal to or higher than the front acceleration reference value is calculated. When the absolute value of the added value is greater than or equal to the front acceleration reference value, the damping force of the front wheel shock absorber is changed to a larger value, and on the other hand, the added value is similarly calculated based on the vertical acceleration of the rear of the vehicle body. The damping force of the rear wheel shock absorber is changed to a larger value when the absolute value of the added value is equal to or greater than the contact section addition reference value.

For this reason, imaging of frequencies below 3 [Hzl] occurring on the vehicle body,
For example, pitching, bouncing, etc. can be detected without exception, and can be quickly brought to a conclusion by appropriately changing the damping force.

In addition, since the imaging state is determined based on the added value of vertical acceleration, it is possible to exclude the influence of high frequency components and accurately detect low frequency (turbulence). Although the configuration has been described so as to detect the n value, the same effect can be produced even if the configuration is configured to calculate the average value, for example.

Furthermore, this embodiment is configured to independently perform damping force change control based on the added value of the vertical acceleration at the front and rear parts of the vehicle body. Therefore, even if the imaging characteristics of the front and rear parts of the vehicle body are different, the imaging of pitching, bouncing, etc. described above can be quickly resolved. In general, there are differences in suspension type, spring constant, damping force, load, etc. between the front and rear parts of a vehicle, so the independent front and rear control as described above is particularly effective in suppressing imaging.

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

Effects of the Invention The shock absorber control device of the present invention applies damping force when the judgment value, which is the accumulation of changes in acceleration from the time when the vertical acceleration of the vehicle body exceeds a predetermined acceleration, to a predetermined period of time, is equal to or greater than a predetermined value. Configured to change to a larger value. Therefore, it is possible to accurately detect relatively low-frequency imaging occurring on the vehicle body, and to change the damping force to a larger value at an appropriate time, which is an excellent effect.

Moreover, with the above effect, it is possible to quickly converge spring-mounted shooting such as pitching and bouncing.

For example, the acceleration detection means independently detects the vertical acceleration of the front and rear parts of the vehicle body, and when the determination value based on the acceleration of the front part is equal to or greater than a predetermined value, the control means On the other hand, if the judgment value based on the rear acceleration is greater than a predetermined value, the damping force of the shock absorber installed between the rear wheels and the vehicle body is changed to a larger value. If the command for changing the force to a larger value is output to each damping force changing means independently, the difference in suspension type, suspension characteristics, load, etc. between the front and rear parts of the vehicle may result in Even if the dynamic characteristics are different, since the front and rear parts of the vehicle body are each controlled independently, relatively low-frequency imaging can be suppressed even more effectively.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, Fig. 2 is a system configuration diagram of an embodiment of the present invention, and Fig. 3 (A>, (B), and (C) are the same). An explanatory diagram when the damping force of the shock absorber is set to a small value,
Figures 4 (A), (B), and (C) are explanatory diagrams when the damping force of the shock absorber is set to a large value, and Figure 5 is a perspective view of the damping force changing actuator of the shock absorber. 6 is a block diagram for explaining the configuration of the electronic control unit (ECU), FIGS. 7 and 8 are flowcharts showing the control, and FIG. 9 is an explanatory diagram showing the prior art. It is. Ml... Acceleration detection means M2... Damping force changing means M3... Control means 1... Shock absorber control device 2... Front acceleration sensor 3... Rear acceleration sensor SIL, S1R, S2L, S2R...Shock absorber AllL, AlR, A2L, A2R...Damping force changing actuator 4...Electronic control unit (ECU) 4a...CPU

Claims (1)

[Scope of Claims] 1. Acceleration detection means for detecting acceleration in the vertical direction of the vehicle body; Damping force changing means for changing the damping force of a shock absorber disposed between the wheels and the vehicle body in accordance with an external command. , when the judgment value, which is the accumulation of changes in acceleration from the time when the acceleration detected by the acceleration detecting means exceeds a predetermined acceleration until a predetermined time elapses, is a predetermined value or more, a command to change the damping force to a larger value; A shock absorber control device comprising: a control means for outputting the damping force to the damping force changing means; 2. The shock absorber control device according to claim 1, wherein the determination value of the control means is an added value of acceleration over the predetermined time. 3. The shock absorber control device according to claim 1, wherein the determination value of the control means is an average value of acceleration over the predetermined time. 4. The acceleration detection means independently detects the vertical acceleration of the front and rear parts of the vehicle body, and the control means is arranged between the front wheels and the vehicle body when the judgment value based on the acceleration of the front part is equal to or higher than a predetermined value. On the other hand, if the judgment value based on the rear acceleration is greater than a predetermined value, the damping force of the shock absorber installed between the rear wheels and the vehicle body is changed to a larger value. The shock absorber control device according to claim 1, wherein commands for changing the force to a larger value are each independently output to the damping force changing means.