JPS62198513A - Damping force control device for hydraulic buffer - Google Patents

Abstract

PURPOSE:To increase comfortableness in a drive in each running condition, by constituting a damping force control device for an automobile, so as to detect the running condition of a vehicle, and make it possible to vary the damping force of each of the extension side and the compression side of a buffer individually, according to said detected running condition. CONSTITUTION:The running condition is detected by a group of sensors 1 constituted of a speed sensor, an accelerator pedal switch and the like, and the output Ss of the sensors is input into a control unit 2. This control unit 2 reads the running condition according to the preset program, and outputs control signal SA, by which the damping force of each of the extension side and the compression side of a hydraulic buffer 3, can be varied individually, according to the information of the sensors, to the hydraulic buffer 3. With this constitution, comfortableness in a drive can be increased, in each running condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a damping force control device that can separately control the damping force of a hydraulic shock absorber in an automobile or the like on an extension side and a compression side.

(Prior Art) In recent years, the requirements for the basic performance of automobiles have become more sophisticated, and there is a tendency for all issues such as driving performance, ride comfort, and handling stability to be achieved at a high level.

In order to address these issues, damping force control devices for hydraulic shock absorbers with a built-in actuator that can appropriately select the damping force of the hydraulic shock absorbers according to road conditions, driving conditions, etc. have been put into practical use. Unexamined Japanese Patent Publication No. 58-1
There is one described in Japanese Patent No. 42047.

This damping force control device detects the running state of the vehicle, and calculates a damping force control value according to the running state based on this detection signal. Based on this calculation result, the actuator of the hydraulic shock absorber is operated to variably control the damping force.

(Problem to be Solved by the Invention) However, in such a conventional damping force control device for a hydraulic shock absorber, the damping force of the hydraulic shock absorber is not differentiated between the extension side and the compression side, but is the same. Since the configuration is such that the vehicle is controlled (that is, controlled in the same manner), from the viewpoint of further improving drivability, it is thought that there is room for improvement in the following points.

For example, the damping force of a hydraulic shock absorber can be divided into hard (H) and soft [
S], if the damping force is set to hard (H) on both the extension side and the compression side, (1) The load sharing of the hydraulic shock absorber on the front wheel side during braking is However, since the damping force on the extension side is also hard (H) at this time, it is difficult to absorb the shock from unevenness on the road surface, resulting in poor ride comfort.

(n) On the other hand, contrary to (1) above, on the rear wheel side, the load burden is reduced, so the damping force on the compression side is the same as the hard CI (
), the wheels cannot follow the unevenness of the road surface, resulting in poor handling and ride comfort.

In this way, if the damping force is the same on both sides, it is desirable to improve the riding comfort further.

(Objective of the Invention) Therefore, the present invention detects the running state of the vehicle and varies the damping force on the extension side and the compression side of the hydraulic shock absorber separately according to the running state. The purpose of this technology is to enable effective damping force control to further improve vehicle ride comfort during braking, acceleration, cornering, and when the number of passengers or load increases.

(Means for Solving the Problems) In order to achieve the above object, the damping force control device for a hydraulic shock absorber according to the present invention detects the running state of the vehicle, as shown in FIG. A detection means a, a control means for calculating control values for separately varying the damping force on the extension side and the compression side of the damping force variable means C according to the running state of the vehicle, and the control means a. The damping force variable means C is provided to separately vary the damping force on the extension side and the compression side based on the control value.

(Function) In the present invention, the running state of the vehicle is detected by the running state detecting means, and control values for varying the damping forces on the extension side and the compression side of the hydraulic shock absorber are determined based on this detection signal to adjust ride comfort. are calculated separately to increase. Then, based on this control value, the damping forces on the expansion side and the compression side are appropriately controlled independently.

Therefore, the most appropriate combination of damping forces on the extension side and compression side can be obtained depending on the driving condition. As a result, it is possible to improve running stability and ride comfort.

(Example) Hereinafter, the present invention will be explained based on the drawings.

2 to 6 are diagrams showing a first embodiment of the present invention.

First, the configuration will be explained. In Fig. 2, ■ is a sensor group as a driving state detection means, and sensor group 1 is composed of a plurality of sensors such as a speed sensor and an accelerator pedal switch pickup, as shown in the item of sensing means in Appendix 1. Ru.

The sensor group 1 is installed at a predetermined position on the vehicle, detects the running state of the vehicle, and sends the sensor output Ss to the control unit 2.
Output to.

The control unit 2 has a function as a control means and is composed of a microcomputer. Then, the control unit 2 reads information regarding the running state of the vehicle from the sensor group 1 according to a program stored in the internal memory, and also adjusts the extension side of the hydraulic shock absorber (damping force variable means) 3 based on this sensor information. Processing values for separately varying each damping force on the compression side are calculated, and a control signal SA corresponding to the calculation result is output to the hydraulic shock absorber 3. Hydraulic shock absorbers vary the damping force on the extension side and compression side separately based on the control signal SA. For example, the damping force can be adjusted by adjusting the damper oil passage area on each side separately using a solenoid valve. A variable type is used.

This type of device was proposed by the present applicant at approximately the same time as the present application.

Next, the effect will be explained.

FIG. 3 is a flowchart showing a damping force control program executed by the control unit 2.
, ~P, indicate each step of the flow. In the following explanation, for convenience of explanation, the expansion side and compression side will be simply referred to as expansion side and overwhelming, respectively, and the expressions hard [H] and soft (S) will be used as appropriate. Both hardware and software [■]
], (S) is omitted.

First, the speed sensor at Pl determines whether or not the vehicle is stopped, and if the vehicle is stopped, the state of the vehicle is
If it is determined that the condition (■) shown in (3) is applicable, the process proceeds to P2; otherwise, the process proceeds to P3. Note that the running state of the vehicle is expressed in correspondence with the symbols ■ to ◎, as shown in Appendix 1, and the expressions ■ to @ will be used hereinafter in the flow as well. In P2, both the extension side and compression side are set to hard (H). This suppresses the shaking of the vehicle when people get on and off the vehicle, and stabilizes the vehicle body the next time it starts. In other words, since they are both hard, sudden lifting of the front side of the vehicle body can be suppressed (see Appendix 2).

In P3, the accelerator pedal switch determines whether the vehicle is accelerating or not, and if it is accelerating, the process advances to P4.
If it is not accelerating, proceed to P.

In P4, the steering angle sensor determines whether the vehicle is turning or not. If the vehicle is turning, it corresponds to driving state ■, so proceed to P2 and set all damping forces to hard as described above. In other words, when the vehicle is accelerating straight ahead), this corresponds to the driving state (2), so the process shown in Appendix 1 is executed at P6. In case (2), the specific control is to set the front (front wheel) part's rebound side to hard and the compression side to soft (S), and set the rear (rear wheel)'s rebound side to soft and overwhelming to hard.

At P, the brake lamp switch determines whether the vehicle is braking or not, and if the vehicle is braking, P7
Proceed to P8 if braking is not in progress.

In P7, it is determined whether or not it is turning using the same means as in P4, and if it is turning, it is determined that it corresponds to the driving state ■ and Pt
If this is not the case (that is, when braking), it is assumed that the vehicle is moving forward (O) or backward (O), and the process proceeds to P6.

In this case, as shown in Attached Table 1, 0-. At 0, the damping forces at the front and rear sections are set to be opposite on the expansion side and the compression side, which is different from the conventional control mode in which the damping forces are the same for both. Therefore, according to the example pointed out as a conventional problem, in this example, the forward force is soft on the rebound side and hard on the overpowering side, so the shock from unevenness on the road surface is absorbed extremely smoothly and the riding comfort is significantly improved. and improve. On the other hand, the rear section is hard on the rebound side and soft on the compression side, allowing the wheels to properly follow uneven road surfaces, improving both steering and ride comfort.

In PI1, it is determined whether or not the vehicle is turning using the same means as in P4 and P, and if the vehicle is turning, the program proceeds to P; otherwise, the program proceeds to P. Proceed to.

At P, the steering angle sensor determines whether the turning is to the right or not. If the turning is to the right, it is determined that the turning corresponds to driving condition LQ (jEE) and the process proceeds to P. If it is not to the right, it is determined whether the turning is to the right or not. In addition to making the rebound side hard and the overwhelming one soft, the LH (left wheel)'s rebound side is soft and the overwhelming one is hard. Further, in the case of O, the front and rear RH's RH rebound sides are both set to soft, the overwhelm is both set to hard, and the LH's rebound side is set to hard, and the overwhelm is set to soft.

On the other hand, in P8, when the vehicle is not turning, it is determined that the running condition corresponds to 80, and PIG is set to soft on both the extension side and the compression side, and the process returns.

In this way, the damping force of the hydraulic shock absorber 3 is controlled in different manners on the rebound side and on the overwhelming side, depending on the various running conditions of the vehicle. Therefore, as described above in detail regarding the state during braking, the drivability of the vehicle can be significantly improved even in various other running states. That is, it is possible to further improve ride comfort and maneuverability during braking, acceleration, cornering, and combinations thereof.

In this embodiment, the sensor group 1 shown in Attached Table 1 is used, and the damping force variable mode is also controlled as shown in Table 1, but the present invention is not limited to these control modes. It goes without saying that the control mode can be modified in various ways within the scope of the purpose of the present invention. In this embodiment, since it is not possible to cover all driving conditions, major conditions are listed as examples.

4 to 8 are diagrams showing a second embodiment of the present invention. This embodiment is an example of application to a vehicle using a vehicle height sensor as a driving state detection means, and the damping force is optimally varied mainly in accordance with changes in vehicle height.

In this embodiment, the hardware configuration is the same as that of the first embodiment, so it will be omitted, and the details of the control will be explained in detail.

The vehicle height is detected by a vehicle height sensor, and the displacement of the vehicle height is calculated from the sensor output. On the other hand, when stopped, the front
The average vehicle height is calculated based on the sensor output when the rear load sharing is equal. Using the above calculation results, a combination is calculated so that the damping force on the expansion side and the compression side are respectively optimal.

First, the first aspect of the combination is shown as shown in FIG. In other words, as shown in Fig. 4, within a predetermined vehicle height width W centered around the standard vehicle height, the same control mode (unified as hard or soft) is used for both rebound and overwhelming as in the general variable range. controlled. On the other hand, when the average vehicle height is lower than the vehicle height width W, the damping force on the compression side is set to be one rank softer than the damping force on the rebound side, and when the average vehicle height is higher than the vehicle height width W, the damping force on the compression side is set to be one rank softer than the damping force on the compression side. It is set in a soft ranking area. This provides a finely tuned damping saw that makes the ride comfortable according to the state of displacement of the vehicle height, further improving the ride comfort.

Further, a second aspect of the above combination is shown as shown in FIG. In Fig. 5, the high side in Fig. 4,
At the limit side of each of the soft areas on the low side, there is a hard area where both the extension side and the overpowering side are set to hard. By doing so, there are the following advantages compared to the case shown in FIG.

That is, in the first mode shown in FIG. 4, the riding comfort is significantly improved, but when the stroke of the hydraulic shock absorber 3 is in a state of compression, the compression side damping force is made weaker and softer than that on the rebound side. Therefore, the stroke in the compression direction tends to become large. For this reason, when the average vehicle height moves further in the compression direction, there is a risk that the piston rond of the hydraulic shock absorber 3 will collide with the stroke end. Therefore, the damping force is maximized (hard) to avoid the risk of collision during compression. This also applies to the expansion side.

Figure 6 is a graph showing changes in vehicle height over time from a stopped state to a constant speed state based on the control mode described above, and the situation during the control is shown in a separate table. Second
It is shown as follows. In this table, the explanation is limited to the selection of the damping force on the extension side and the compression side of the front section especially during acceleration.

However, L0 to tl: Stopped state 1, -12: Acceleration state t2 to t3 D. Constant speed state ■, ■: When the unevenness of the road surface is relatively small ■, ■: When the unevenness of the road surface is relatively large In Fig. 6 , when stopped (to
~t, ), there is no input from the road surface, so both the expansion side and the compression side may be set to either hard or soft. In addition, at constant speed (ttxt), in order to absorb the shock of uneven road surfaces, if ■ (that is, the unevenness of the road surface is large), both the rebound and compression sides are set to soft, and ■ (also when the unevenness is small)
If so, the shock from unevenness is small, so you can set it to either hard or soft. Therefore, these states are exactly the same as before. On the other hand, during acceleration (t, xt
,), both the rebound and compression sides are made harder to suppress the sudden rise of the front and stabilize the condition of the car body.

In addition, when the average vehicle height exceeds a certain value in ■ (small unevenness), only the rebound side is changed to soft to improve ride comfort, and in ■ (large unevenness), only the rebound side is made soft. As a result, during acceleration (1+ to tz), compared to the conventional example, it is possible to achieve the effect of stabilizing the vehicle body during acceleration and further attenuating shocks from unevenness on the road surface.

Furthermore, as a third aspect, there is the following, for example. That is, when the average vehicle height is low (vehicle load increases), the amount of energy of vertical vibration of the vehicle due to unevenness of the road surface increases, and the amount of energy absorbed by the hydraulic shock absorber 3 also increases. Therefore, with the same damping force, it takes a longer time to absorb vertical vibrations, leading to deterioration of riding comfort. Therefore, when the load increases, the damping force is set to a high damping force region on both the compression side and the rebound side, that is, hard. Please note that this load increase is due to the front and rear wheels when stopped.
Both average vehicle heights are low (judge based on the condition).

In this way, in this embodiment, the damping force is selected in detail depending on the occupant and the load, and the riding comfort can be further improved.

In each of the above embodiments, the damping force of the hydraulic shock absorber is overpowered as the damping force variable means, and the damping force is switched to two stages, hard [H] and soft l-(S), respectively on the rebound side. Switching is not limited to this. For example, in a vehicle where both the overwhelming and rebound sides can be switched to three levels: hard [H], medium [M], and soft (S), the occupant (
When the number of occupants (and load) is small, both the compression side and the extension side are switched in three stages, and a combination of soft (S) and medium CM) is selected, and when the number of occupants (and load) is large, the combination is selected between overwhelming and soft (S) for both the compression side and the extension side. It is also possible to combine damping forces so as not to select . In addition, during acceleration, the damping force can be switched in multiple stages or continuously variable on both the compression and rebound sides, such as setting the compression side of the front section to hard [H] and the rebound side to medium CM), allowing for more precise damping force control. It goes without saying that the present invention can also be applied to those that have achieved this.

(Effects) According to the present invention, since the damping force on both the compression side and the rebound side is independently variable according to the running condition of the vehicle, the damping force can be finely tuned to the optimum combination, improving ride comfort and handling. It is possible to further improve sexual performance.

[Brief explanation of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 and 3 are diagrams showing a first embodiment of a damping force control device for a hydraulic shock absorber according to the present invention, and FIG. 2 is an overall configuration diagram thereof, and FIG. FIG. 3 is a flowchart showing a program for variable damping force control, FIGS. 4 to 6 are diagrams showing a second embodiment of the damping force control device for a hydraulic shock absorber according to the present invention, and FIG. Fig. 5 is a diagram showing another example of the average vehicle height and damping force control value, Fig. 6 is a time chart showing changes in vehicle height. It is. 1...Sensor group (running state detection means), 2...
...Control unit (control B means), 3.
...Hydraulic shock absorber (damping force variable means).

Claims (1)

[Claims] A) a running state detection means for detecting the running state of the vehicle; and b) a damping force variable means for varying the damping force on the extension side and the compression side separately according to the running state of the vehicle. c) a damping force variable means that separately varies the damping force on the extension side and the compression side based on the control value of the control means; A damping force control device for a hydraulic shock absorber.