JPH06270635A - Suspension control device - Google Patents

Abstract

PURPOSE:To provide a suspension control device which can suppress frequent changeover setting of the damping factor. CONSTITUTION:A suspension control device has a controller 20 which controls a shock absorber 3 equipped with a variable damping factor so that the reference damping force is obtained when the value of object relative displacement data exceeds the regional medium value of the relative displacement reference data relative to the value of the foregoing object relative displacement data, wherein the controller 20 stops the control for generating the reference damping force based upon the relative displacement data if the relative speed lies outside of the relative speed reference data which underwent the regional setting. When the relative speed lies outside of the relative displacement reference data, the control for generating the reference damping force based upon the relative displacement data is stopped, so that changingover of the damping factor for generating the reference damping force does not take place even though the value of the relative displacement data exceeds the regional medium value of the relative displacement reference data, and frequent changeover setting of the damping factor can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device used in an automobile.

[0002]

2. Description of the Related Art An example of a conventional suspension control device is shown in FIGS. In the figure, a vehicle body 1 and four pieces (only one is shown in the figure) constituting the vehicle.
A variable damping coefficient shock absorber 3 and a spring 4 are interposed between the vehicle 2 and the wheel 2 side to support the vehicle body 1. Although four damping coefficient variable shock absorbers 3 and four springs 4 are provided for each of the four wheels 2, only one of them is shown for convenience.

The damping coefficient variable shock absorber 3 can be adjusted in damping coefficient according to the position of a passage area adjuster (not shown) driven by the actuator 5.
The vehicle body 1 is provided with vertical acceleration detecting means 6 for detecting vertical acceleration acting on the vehicle body 1. This vehicle is provided with a relative displacement detecting means 7 for detecting the relative displacement between the vehicle body 1 and the unsprung part (axle). A controller 8 is provided so as to be connected to the vertical acceleration detecting means 6, the actuator 5 and the relative displacement detecting means 7. The controller 8 performs the following arithmetic processing and controls the connected equipment based on the arithmetic result. The calculation contents of the controller 8 will be described.

FIG. 5 is a main program (main routine) of the controller 8. First, initial setting is performed (step S1), and in the next step S2, the sensors of the vertical acceleration detecting means 6 and the relative displacement detecting means 7 are respectively detected. Then, in step S3, the detected value of the vertical acceleration detecting means 6 is integrated to obtain the absolute speed (dX ₁ / dt), and the detected value of the relative displacement detecting means 7 is differentiated to obtain the relative speed. (dX ₁
/ Dt−dX ₀ / dt) is obtained. Following step S3, control of the basic control logic based on the Karnopp control law is performed (steps S4, S5, S6).

Here, the Carknop control law will be explained (the details of the Carknop control law are described in ASME, Journal of
Engineering for Industry No. 96-2 P.619 ~ 626 (Ma
y, 1974). ). Carknop's control rule is that the damping force to be obtained by the sign of the product of the absolute velocity on the spring (dX ₁ / dt) and the relative velocity between the vehicle body 1 and the unsprung (dX ₁ / dt− dX ₀ / dt), and The purpose is to obtain the damping coefficient, and the idea is shown by the following equation.

IF (dX ₁ / dt) (dX ₁ / dt− dX ₀ / dt)> 0 (1) (corresponding to YES in step S4) F = −C _S dX ₁ / dt = −C (dX ₁ / dt− dX ₀ / dt) (2) ∴C = C _S (dX ₁ / dt) / (dX ₁ / dt− dX ₀ / dt) (3) IF (dX ₁ / dt) ( dX ₁ / dt− dX ₀ / dt) ≦ 0 (4) (corresponding to NO judgment in step S4) F = 0 (5) ∴C = 0 (6) where X ₁ : sprung (Vehicle) displacement X ₀ : Unsprung (road surface) displacement F: Shock absorber damping force C _S : Damping coefficient of shock absorber provided between sprung and absolute coordinate system C: Sprung and unsprung Damping coefficient of shock absorber installed between

In the equation (3), the damping coefficient is obtained by approximating C = H (hard) (7) (step S5). In addition, although C = 0 in the equation (6) of the Carnop control law, C = S (≠ 0) (soft) (8) in this basic control logic due to the control delay due to the change in vibration. Yes (step S6). That is, in this basic control logic, in the case of the condition of the expression (1), the passage area adjusting body is provided at the position corresponding to the expression (7), and in the case of the condition of the expression (4), the passage area adjusting body is provided at the position corresponding to the expression (8). Set.

Steps subsequent to the processing of step S5 or S6
In S7, the value of the relative displacement (X ₁ −X ₀ ) from the relative displacement detection means 7 is compared with the relative displacement reference data (hatched in FIG. 6) set as the dead zone region T _h , and the relative displacement If the value is larger than the relative displacement reference data of the area T _h , YES is determined and the process proceeds to step S8, where the value of the relative displacement data of the target cycle (current cycle) is a negative value (area intermediate value of the relative displacement reference data (vehicle High neutral point) is set to “0”)).

If YES is determined in step S8, step S9
Go to step S10 to determine whether the value of the relative displacement data of the previous target cycle (previous cycle) is a plus value, and if NO, proceed to step S10 to move the relative displacement data of the previous target cycle (previous cycle). It is determined whether the value of is a negative value.
If YES is determined in step S9 or S10, step S11
Then, the passage area adjusting body is set so as to obtain the reference damping force (in this case, the soft reference damping force is set as the soft characteristic). That is, by performing the processing of steps S8 to S9, the value of the target relative displacement data exceeds the area intermediate value (vehicle height neutral point) of the relative displacement reference data with respect to the value of the previous target relative displacement data (vehicle height neutral point). The damping coefficient is set so that a soft damping force characteristic can be obtained regardless of the control of the basic control logic in steps S5 to S7 when the neutral point is passed).

[0010]

[SUMMARY OF THE INVENTION Incidentally, in the above-described suspension control system, when traveling on a general road surface, the value of the relative displacement data is within the region T _h from the area T _h outside the relative displacement reference data, the reference Switching setting is performed so as to obtain damping force (soft damping force characteristic in the suspension control device shown in FIGS. 4 and 5). However, in order to add hysteresis to this switching, the switching is performed when the value of the relative displacement data exceeds the intermediate value (vehicle height neutral point) of the area T _h of the relative displacement reference data. Therefore, when the value of the relative displacement data exceeds the area intermediate value of the relative displacement reference data as shown in the time period a-b and the time period c-d in FIG.
There is a problem that the damping coefficient is temporarily switched so as to obtain the reference damping force (soft damping force), and the damping coefficient is frequently switched depending on the road surface condition. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a suspension control device capable of suppressing frequent switching of damping coefficients.

[0011]

In order to achieve the above object, the present invention is controlled by a controller and the magnitude of a damping coefficient can be adjusted by an actuator, and is interposed between a sprung and an unsprung of a vehicle. A damping shock absorber with a variable damping coefficient, and relative displacement detection means for detecting relative displacement between the sprung and unsprung, and relative displacement data detected by the relative displacement detection means and relative displacement reference data set as a dead zone region. In a suspension control device in which the controller controls the actuator of the damping coefficient variable shock absorber so as to obtain a preset reference damping force when the value of the relative displacement data is within the range of the relative displacement reference data. , The controller determines that the relative speed between the sprung and unsprung parts is outside the standard speed reference data set in the area. If it, characterized by stopping the control for obtaining a reference damping force based on the relative displacement data.

[0012]

With the above structure, when the relative velocity is out of the relative displacement reference data, the control for obtaining the reference damping force based on the relative displacement data is stopped. The damping coefficient is not switched to obtain the reference damping force even within the reference data area.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension controller according to a first embodiment of the present invention will be described below with reference to FIGS. In addition,
The same members and parts as those shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. The controller 20 of the present embodiment performs arithmetic processing as shown in FIG. 5 and controls the connected device based on the arithmetic result. The calculation content of the controller 20 is the calculation content of the controller 8 between step S7 and step S8 of FIG.
However, the other steps are the same. In step S20, the relative velocity in the current cycle is in the dead zone region (the threshold value of this region is V _S. )
It is determined whether or not the relative speed reference data set as (indicated by hatching in FIG. 3) is within (small), and if NO is determined, the process returns to step S2 to perform processing, while YES is determined. Then, step S8 to step
Proceed to S11 to execute the processing described above.

In the suspension controller thus constructed, the relative speed is outside the relative speed reference data (threshold value).
V _S or more), step S8 or step
The control of the actuator 5 accompanying the processing of S11 is stopped.
That is, as shown in the time period a′-b ′ and the time period c′-d ′ in FIG. 3, even if the value of the relative displacement data exceeds the area intermediate value of the relative displacement reference data (passes the vehicle height neutral point). However, if the relative speed is out of the relative speed reference data, the actuator 5 is not controlled in accordance with the processing of steps S8 to S11. Therefore, even if the value of the relative displacement data exceeds the area intermediate value of the relative displacement reference data (even if it passes the vehicle height neutral point), the value of the relative displacement data exceeds the area intermediate value of the relative displacement reference data. In this case, the switching of the damping coefficient for obtaining the reference damping force (soft damping force), which has been conventionally performed, is not performed. As a result, in the suspension control device of the present invention, it is not necessary to frequently change the damping coefficient that could occur in the conventional suspension control device. In addition, since the above-mentioned frequent switching of the damping coefficient is not performed, the life of the actuator 5 is extended correspondingly, and the change in the attitude of the vehicle is reduced.

In the above embodiment, the reference damping force is switched when the intermediate point of the relative displacement reference data is exceeded, but when it is not necessary to add hysteresis to the switching as described above, The reference damping force may be switched when the relative displacement data falls within the area of the relative displacement reference data. Also, the variable damping coefficient shock absorber has been described as a two-step switching of the damping coefficient between hard and soft, but, for example, multi-step switching such as three-step or four-step is possible and there are multiple steps depending on the magnitude of the absolute speed and the relative speed. The switching control of the damping coefficient may be performed.

[0016]

Since the present invention is the suspension control device configured as described above, when the relative speed is outside the relative displacement reference data, the reference damping force based on the relative displacement data is obtained. Since the control is stopped, even if the value of the relative displacement data exceeds the area intermediate value of the relative displacement reference data, the switching of the damping coefficient to obtain the reference damping force is not performed, which can occur in the conventional suspension control device. Frequent switching of the damping coefficient is suppressed.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a suspension control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control content of a controller of the suspension control device.

FIG. 3 is a diagram showing a damping coefficient switching timing of the controller.

FIG. 4 is a diagram schematically showing an example of a conventional suspension control device.

FIG. 5 is a flowchart showing a control content of a controller of the suspension control device.

FIG. 6 is a diagram showing a damping coefficient switching timing by a conventional suspension control device.

[Explanation of symbols]

 1 vehicle body 2 wheels 3 damping coefficient variable shock absorber 5 actuator 7 relative displacement detection means 20 controller

Claims (1)

[Claims] 1. A damping coefficient variable shock absorber, which is controlled by a controller and whose magnitude of damping coefficient can be adjusted by an actuator, is interposed between a sprung portion and an unsprung portion of a vehicle, and a relative relation between the sprung portion and the unsprung portion. A relative displacement detecting means for detecting displacement, and the relative displacement data detected by the relative displacement detecting means and the relative displacement reference data set as the dead zone region are compared every predetermined period, and the value of the relative displacement data is the relative displacement reference. In a suspension control device in which the controller controls the actuator of the variable damping coefficient shock absorber so as to obtain a preset reference damping force when it is within the area of the data, in the controller, the relative speed between the sprung and unsprung is When it is outside the set relative velocity reference data, the reference damping force based on the relative displacement data is obtained. Suspension control device characterized by stopping the control for.