JP2011042263A - Variable damper control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable damper control device that can improve the driver's operability of a vehicle by optimizing a pitch response even if a usage of the vehicle is varied. <P>SOLUTION: The variable damper control device includes a steering amount detecting means 31 for detecting a steering amount of a vehicle steering system, a steering feature amount calculating means 33 for calculating a steering feature amount based on an output of the steering amount detecting means, and a damping force alteration means 37 and 38. The steering feature amount is a parameter correlated to the advance or the retard of a driver's operation with respect to a predetermined steering pattern. The damping force alteration means alter damping force properties of at least one of a front damper and a rear damper based on a result of comparing the steering feature amount with a predetermined target value so that an elastic ratio of the damping force of the front damper provided to a front suspension may relatively be changed with respect to an elastic ratio of the damping force of the rear damper provided at a rear suspension. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a variable damper control device that controls a damping force of a variable damper provided in a suspension device of a vehicle such as an automobile, and in particular, optimizes a pitch response regardless of a vehicle speed and a steering method, thereby improving the ease of driving the vehicle. Concerning improved ones.

BACKGROUND ART A suspension device for an automobile supports a wheel support member through a suspension arm that swings with respect to a vehicle body so as to allow a stroke. Such a suspension device includes a spring that generates a spring reaction force according to the stroke amount and a damper (shock absorber) that generates a damping force according to the stroke speed.
The damper generates a damping force by resistance when a working fluid such as oil passes through a flow path such as an orifice or a valve. A variable damper is also known in which the damping characteristic can be adjusted by switching the oil channel cross-sectional area with an actuator.

When a variable damper is used, it is possible to control the roll rate, pitch rate, etc. of the vehicle.
For example, Patent Document 1 describes that a variable damper is controlled so as to suppress a phase difference between a roll period and a pitch period of a vehicle within a predetermined range for the purpose of reducing the driving burden on the driver.

JP 2007-313951 A

However, the usage status of the vehicle by each driver does not always coincide with the conditions (for example, vehicle speed, steering pattern, etc.) when the damping characteristics of the suspension damper are determined during vehicle development. For this reason, there is a concern that the vehicle will deviate from the optimal sprung behavior and become difficult to drive by the driver due to changes in the vehicle speed, the way of steering due to individual differences among drivers, manufacturing variations, and the like.
In addition, it is difficult to actually measure parameters related to pitch response, such as pitch phase and pitch rate, while driving an actual vehicle, and there is a demand for establishment of a method for optimizing pitch response even when these parameters cannot be measured directly. Yes.
An object of the present invention is to provide a variable damper control device capable of optimizing the pitch response and improving the ease of driving even when the use situation of the vehicle varies.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is a steering amount detection means for detecting a steering amount in a steering system of a vehicle, and a parameter correlated with advance or delay of a driver operation with respect to a predetermined steering pattern based on an output of the steering amount detection means. Based on the result of comparing the steering feature amount with a predetermined target value, the expansion ratio of the damping force of the front damper provided on the front suspension is provided on the rear suspension. Further, the variable damper control device includes a damping force changing unit that changes a damping force characteristic of at least one of the front damper and the rear damper so as to change relative to the expansion / contraction ratio of the damping force of the rear damper.

According to a second aspect of the present invention, in the variable damper control device according to the first aspect, the target value is obtained by smoothing the steering feature amount mapped for different vehicle speeds and steering operation amounts. is there.
According to a third aspect of the present invention, in the variable damper control device according to the first aspect, the target value is a preset constant.

According to the present invention, the following effects can be obtained.
(1) The expansion / contraction ratio of the damping force of the front damper provided in the front suspension based on the result of comparing the steering feature amount, which is a parameter correlated with the advance or delay of the driver operation with respect to the predetermined steering pattern, with the predetermined target value. By changing the damping force characteristics so that changes relative to the expansion / contraction ratio of the damping force of the rear damper provided on the rear suspension, it is conscious of the pitch phase that is actually difficult to detect and the target pitch phase. Even if it is not, it is possible to optimize the pitch responsiveness of the vehicle by learning control and provide a vehicle that is easy for the driver to drive.
(2) By smoothing the steering feature values mapped for different vehicle speeds and steering wheel operation amounts to obtain target values, the vehicle pitch response characteristics do not change suddenly due to changes in the vehicle speed and steering wheel operation amounts. It is possible to provide a vehicle that is easy to perform.
(3) By setting the target value to a preset constant, the effect of the item (1) can be obtained with a simple hardware configuration and a reduced calculation load.

It is a figure which shows the structure of the Example of the variable damper control apparatus to which this invention is applied. It is a figure which shows an example of the map which accumulate | stored the handle operation feature-value with respect to the vehicle speed and handle | steering-wheel operation amount representative value in the variable damper control apparatus of FIG. It is a figure which shows an example of the map which accumulate | stored the target value of the handle operation characteristic amount with respect to the vehicle speed and the handle operation amount representative value in the variable damper control device of FIG. It is a figure which shows an example of the map which accumulate | stored the damper instruction | indication value according to the level of the difference value of the target value of steering wheel operation feature-value in the variable damper control apparatus of FIG. 1, and an actual value. 2 is a graph showing an example of a change in damping force characteristic of a damper of a front suspension in the variable damper control device of FIG. 1. It is a graph which shows the correlation with the roll angle at the time of driving | running | working, steering the front-wheel rudder angle of a vehicle to right and left like a sine wave shape. It is a graph which shows the difference in the effectiveness of the rudder by the steering wheel operation characteristic amount, pitch phase, and sensory evaluation in a plurality of specifications in which the damping force characteristics of the front and rear dampers are different. It is a graph which shows an example of a driver's handle operation in case a pitch phase to a roll is advanced. It is a graph which shows an example of a driver's handle operation in case a pitch phase to roll is late.

  The present invention presents a problem of providing a variable damper control device that can improve the ease of driving by optimizing the pitch response even when the use situation of the vehicle varies. This was solved by relatively changing the expansion / contraction ratio of the damping force of the variable damper provided in the suspension based on the difference between the target value of the steering operation characteristic amount and the actual value.

Embodiments of a variable damper control device to which the present invention is applied will be described below.
The variable damper control device of the embodiment is provided in a four-wheeled vehicle such as a passenger car, for example, and controls the damping force of the variable damper provided in each of the left and right front suspensions and the rear suspension.

  The vehicle includes a damper FL11, a damper FR12, a damper RL13, and a damper RR14. Further, the vehicle is a damper actuator FL21, a damper actuator FR22, a damper actuator RL23, a damper actuator RR24, a handle angle sensor 31, a vehicle speed sensor 32, a handle as a variable damper control device that controls the damping force of each of the dampers 11-14. An operation amount representative value calculation unit 33, a handle operation feature value calculation unit 34, an intermediate characteristic calculation unit 35, an intermediate characteristic target value calculation unit 36, a damping force instruction value calculation unit 37, a damping force control device 38, and the like are provided.

The dampers FL11 and FR12 are provided on the left and right front suspensions, respectively.
The damper RL13 and the damper RR14 are provided on the left and right rear suspensions, respectively.
The front suspension and the rear suspension support a hub bearing housing that rotatably supports a front wheel and a rear wheel by a suspension arm that swings with respect to a vehicle body.

  The front suspension and the rear suspension include suspension springs that generate a spring reaction force according to the stroke. Each of the dampers 11 to 14 is provided in parallel with the front and rear, left and right suspension springs, and generates a damping force corresponding to the piston speed (suspension stroke speed). The damping force is generated by resistance when damper oil passes through a flow path such as an orifice or a valve during the stroke of each of the dampers 11 to 14. In addition, each of the dampers 11 to 14 can change the damping force characteristics in a plurality of stages by changing the flow path cross-sectional area by switching the flow path of the damper oil. This point will be described in detail later.

  The damper actuator FL21, the damper actuator FR22, the damper actuator RL23, and the damper actuator RR24 are provided in the damper FL11, the damper FR12, the damper RL13, and the damper RR14, respectively, and drive, for example, a damper oil flow switching mechanism of each corresponding damper. Etc. are provided.

  The steering wheel angle sensor 31 is provided in a steering mechanism that converts the rotation of a steering wheel (not shown) into a reciprocating motion in the vehicle width direction and transmits it to the hub bearing housing of the left and right front wheels via tie rods. The handle angle sensor 31 includes an encoder that detects an angular position of a steering shaft that is a rotation shaft coupled to a steering wheel. The output is provided to the handle operation amount representative value calculation unit 33 and the handle operation feature amount calculation unit 34.

  The vehicle speed sensor 32 is provided in each of the right and left front wheel and rear wheel hub bearing housings, and outputs a vehicle speed pulse signal corresponding to the rotational speed of the hub to which the wheel is fixed. The output of the vehicle speed sensor 32 is provided to the handle operation amount representative value calculation unit 33 and the handle operation feature amount calculation unit 34.

θ：ハンドル角
Ｔ：区間時間

また、ハンドル操作量代表値として、式１により求められるハンドル角絶対値の時間平均に代えて、以下の式２により求められるハンドル角速度絶対値の時間平均を用いることもできる。

The handle operation amount representative value calculation unit 33 calculates the handle operation amount representative value U, which is the time average of the handle angle absolute values, using the following Equation 1.

θ: Handle angle T: Section time

Further, as the handle operation amount representative value, the time average of the handle angular velocity absolute value obtained by the following equation 2 can be used instead of the time average of the handle angle absolute value obtained by the equation 1.

The steering wheel operation feature amount calculation unit 34 calculates a steering wheel operation feature amount (steering feature amount) A using the following Expression 3. This steering wheel operation characteristic amount A is a deviation of steering wheel angular velocity component between the cutting side until the steering angle increases from zero to the maximum steering angle and the return side until the steering angle decreases from zero to the maximum steering angle (steering angle). This is a value indicating how much the transition pattern is distorted with respect to the sine wave) (steering wheel angular velocity advance correction value).

The intermediate characteristic calculator 35 calculates the handle calculated by the handle operation feature amount calculator 34 according to the vehicle speed V detected by the vehicle speed sensor 32 and the handle operation amount representative value U calculated by the handle operation amount representative value calculator 33. The operation feature A is mapped.
FIG. 2 is a diagram illustrating an example of a map of the handle operation feature amount A. As illustrated in FIG.
In this map, the handle operation feature amount A () corresponding to each of the different vehicle speeds V (V ₁ , V ₂ ... V _n ) and the handle operation amount representative value U (U ₁ , U ₂ ... U _m ). data is accumulated about the A ₁₁ ~A _mn). This map shows the tendency of the steering operation by the driver currently driving the vehicle.

The intermediate characteristic target value calculation unit 36 performs a surface approximation process (smoothing process) such as a cubic B-spline curved surface for the map of the handle operation feature amount A generated by the intermediate characteristic calculation unit 35, and further The target value B of the handle operation feature value is calculated by multiplying the whole by a coefficient k (0 <k ≦ 1). Similar to the steering wheel operation feature amount A, the steering wheel operation feature amount target value B is mapped according to the vehicle speed V and the steering wheel operation amount representative value U.
FIG. 3 is a diagram illustrating an example of a map of target values of handle operation feature amounts.
In this map, the target of the steering operation feature amount corresponding to each of the different vehicle speeds V (V ₁ , V ₂ ... V _n ) and the steering operation amount representative value U (U ₁ , U ₂ ... U _m ). Data relating to the value B (B _{11 to} B _mn ) is accumulated.

The damping force instruction value calculation unit 37 divides the difference value representing the actual handle operation feature amount A from the target value B of the handle operation feature amount into a plurality of stages (−N..., −2, − ₁ , 0, ₁ , 2,... N), damper indication values C ₁₁ , C ₁₂ ... C _1m of the front suspension damper FL11 and damper FR12, and dampers RL13 and RR14 of the rear suspension. The instruction values C ₂₁ , C ₂₂ ... C _2m are set.
FIG. 4 is a diagram illustrating an example of a map in which the damper instruction values of the dampers 11 to 14 corresponding to the difference value levels are accumulated. Such a combination of front and rear damper instruction values is set in advance by, for example, analysis during sensor development or sensory evaluation using an actual vehicle.

Each of the dampers 11 to 14 is a variable damper whose damping force characteristic can be changed according to a set damper instruction value.
FIG. 5 is a graph showing an example of a change in damping force characteristics in the dampers FL11 and FR12 of the front suspension. In FIG. 5, the horizontal axis indicates the suspension stroke speed (damper piston speed), the right side indicates the expansion side (rebound side), and the left side indicates the contraction side (bump side / pressure side). The vertical axis shows the damping force.
When the damper instruction value is changed, the damping force changes on both the expansion side and the contraction side, but the change in the damping force on the expansion side is larger than that on the contraction side. As a result, the damping force ratio (expansion / contraction ratio) between the expansion side and the contraction side is also changed by changing the damper instruction value.
Further, the dampers RL13 and RR14 of the rear suspension have substantially the same characteristics.

  The damping force control device 38 controls the damper actuators 21 to 24 based on the damper instruction values of the dampers 11 to 14 set by the damping force instruction value calculation unit 37, and changes the damping forces of the dampers 11 to 14. It is something to be made.

Next, the effect of the pitching behavior of the vehicle on the driver's steering operation will be described.
FIG. 6 is a graph showing the correlation between the roll angle and the pitch rate when traveling while steering left and right so that the front wheel steering angle of the vehicle is sinusoidal, the horizontal axis indicates the roll angle, and the vertical axis Indicates the pitch rate (first-order differential value of the pitch angle).
As shown in FIG. 6A, when there is no phase delay of the pitch rate with respect to the roll angle, the pitch rate is also substantially zero when the roll angle is zero.
On the other hand, as shown in FIG. 6B, when the phase of the pitch rate is delayed with respect to the roll angle, the pitch rate does not become zero even when the roll angle is zero. This indicates that the pitch rate when the roll angle is zero can be used as a parameter indicating the advance and delay of the pitch phase with respect to the roll phase. Here, when the pitch rate when the roll angle is zero is positive (front dive direction), the pitch phase is advanced with respect to the roll phase. In general, when the roll angle increases, the feeling in sensory evaluation is better when the pitch is in the positive direction (front dive direction).
Further, FIG. 7 shows the difference in steering operation characteristics, pitch phase, and rudder effectiveness according to sensory evaluation in specifications 1 to 4 having different damping force characteristics of the front and rear dampers. It can be seen that there is a clear correlation between the effectiveness of the rudder by the evaluation. That is, the steering wheel operation feature amount can be used as a parameter correlated with the pitch phase and the effectiveness of the rudder.

Hereinafter, in order to facilitate understanding, case 1 and case 2 which are typical vehicle specifications having different personalities will be described.
Table 1 shows the tendency of the front / rear damper damping force, the front / rear ratio of the damper expansion / contraction ratio, the tendency of the pitch phase, the tendency of the initial steering phase, the tendency of the steering advance component, and the feeling in sensory evaluation in Case 1 and Case 2. Various tendencies are relative when case 1 and case 2 are compared.

As shown in Table 1, the case 1 sets the damping force of the dampers FL11 and FR12 of the front suspension to the hard side. As a result, the expansion side damping force becomes relatively large with respect to the compression side damping force at the front, and the expansion / contraction ratio of the damping force increases.
On the other hand, the damping force of the dampers RL13 and RR14 of the rear suspension is set to the soft side. Thereby, at the rear, the expansion side damping force becomes relatively small with respect to the compression side damping force, and the expansion / contraction ratio of the damping force becomes small.
As a result, the front / rear ratio of the expansion / contraction ratio increases.

FIG. 8 is a graph showing an example of the steering wheel operation history of the driver in case 1, in which the horizontal axis indicates time and the vertical axis indicates the steering angle (steering wheel angle) (the same applies in FIG. 9).
In case 1, since the pitch phase is advanced with respect to the roll phase, the driver tends to turn the steering wheel at the initial stage of steering due to the unintentional influence of the roll (point P11 in FIG. 8). . For this reason, although the driver is aware that the steering angle is increased to some extent, he / she feels that the vehicle does not turn as much as he / she thinks and feels insensitive.
The driver who feels that the responsiveness of the vehicle is worse than the actual vehicle, increases the steering wheel (point P12 in FIG. 8).
Thereafter, the driver corrects the steering in order to travel according to the target course, so that the steering wheel is returned quickly (point P13 in FIG. 8).
Due to the above-described tendency, in case 1, the steering waveform is a waveform that turns quickly and returns slowly, and the steering advance component (steering operation characteristic amount) increases.

In the case 2, as shown in Table 1, the damping force of the damper FL11 and the damper FR12 of the front suspension is set to the soft side. As a result, the expansion side damping force becomes relatively small with respect to the compression side damping force at the front, and the expansion / contraction ratio of the damping force becomes small.
On the other hand, the damping force of the dampers RL13 and RR14 of the rear suspension is set to the hard side. As a result, at the rear, the expansion side damping force is relatively large with respect to the compression side damping force, and the expansion / contraction ratio of the damping force is increased.
As a result, the front / rear ratio of the expansion / contraction ratio becomes small.

FIG. 9 is a graph showing an example of a driver handle operation history in case 2.
In case 2, since the pitch phase is delayed with respect to the roll phase, the driver tends to turn the steering wheel too early in the steering operation due to the influence of the roll unintentionally (point P21 in FIG. 9). For this reason, although the driver is not conscious of increasing the steering angle so much, the driver feels that the vehicle is turning too much and feels sensitive.
The driver who feels that the responsiveness of the vehicle is better than the actual vehicle turns the steering wheel back or reduces the steering speed toward the increased side (point P22 in FIG. 9).
Thereafter, the driver corrects the steering to travel according to the target course, and therefore delays the return of the steering wheel (point P23 in FIG. 9).
Due to the above tendency, in case 2, the steering waveform turns slowly and returns quickly, and the steering advance component (steering operation characteristic amount) becomes small.

In the variable damper control device according to the present embodiment, when the difference obtained by subtracting the target value from the actual value of the handle operation feature amount is positive, it is assumed that the pitch phase is advanced with respect to the target. The expansion / contraction ratio of the damper FR12 is made relatively small with respect to the expansion / contraction ratio of the rear damper RL13 and the damper RR14. As a result, the pitch phase is delayed and approaches the target.
On the other hand, if the difference obtained by subtracting the target value from the actual value of the handle operation feature value is negative, the pitch phase is delayed with respect to the target, and the expansion / contraction ratios of the front damper FL11 and damper FR12 are It is relatively increased with respect to the expansion / contraction ratio of the damper RL13 and the damper RR14. As a result, the pitch phase advances and approaches the target.

Even if the pitch phase has a leading or lagging tendency as in case 1 or case 2, it is considered that the driver usually adapts as he / she becomes accustomed and performs a steering operation in accordance with the characteristics of the vehicle. However, if the pitch phase advance and delay characteristics constantly change depending on the vehicle speed and the amount of steering operation, the driver is difficult to adapt and the vehicle is difficult to drive.
In this regard, according to the embodiment, the steering wheel operation feature amount, which is a parameter indicating the progress and delay of the steering wheel operation of the driver, is mapped with the vehicle speed and the steering wheel operation amount, and the smoothed value is set as the target value, and the target value and the actual By setting the front and rear damper damping force according to the difference level of the value, the change of the pitch response characteristic of the vehicle is made gentle, and the pitch response characteristic does not change suddenly even when the driving conditions such as the vehicle speed change A vehicle that is easy to drive can be provided.
Further, according to the present embodiment, the pitch response is optimized by using the steering operation characteristic amount calculated based on the output of the steering angle sensor 31 without directly measuring the pitch response of the vehicle that is difficult to measure. be able to.
Furthermore, according to the present embodiment, since the front and rear damper damping force instruction values are selected from combinations that have been tuned in advance in the development stage, the roll characteristics, ride comfort, and other performance required for the damper Both can be achieved.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The mechanical configuration of the variable damper control device is not limited to that of the above-described embodiment, and can be changed as appropriate. For example, a function realized by common hardware in the embodiment may be allocated to a plurality of hardware, or conversely, a function realized by a plurality of hardware may be provided in the common hardware. Further, the damping force adjustment method in the variable damper is not limited to the one that switches the damper oil flow path as in the embodiment. For example, a variable damper using an MR fluid whose viscosity increases when a magnetic field is applied may be used.
(2) In the embodiment, the handle operation feature amount is calculated using the above-described equation 3. However, the parameter correlated with the advance or delay of the handle operation is not limited to such a handle operation feature amount, for example, the handle angular velocity. On the other hand, a value obtained by performing a low pass filter, a high pass filter process or the like may be used. Further, not only a value based on the steering wheel angle, but also a parameter correlated with the progress or delay of the steering wheel operation may be obtained based on the steering torque input from the driver to the steering system.
(3) In the embodiment, the steering wheel operation feature amount is mapped by the vehicle speed and the steering wheel operation amount, and this is smoothed to set the target value. However, the present invention is not limited to this, and the target value is set by other methods. May be. For example, the target value may be a preset value.

11 Damper FL 12 Damper FR
13 Damper RL 14 Damper RR
21 Damper actuator FL 22 Damper actuator FR
23 Damper Actuator RL 24 Damper Actuator RR
DESCRIPTION OF SYMBOLS 31 Steering angle sensor 32 Vehicle speed sensor 33 Steering wheel operation amount representative value calculation part 34 Steering wheel operation amount calculation part 35 Intermediate characteristic calculation part 36 Intermediate characteristic target value calculation part 37 Damping force instruction value calculation part 38 Damping force control device

Claims (3)

Steering amount detection means for detecting a steering amount in a steering system of the vehicle;
Steering feature amount calculating means for calculating a steering feature amount that is a parameter correlated with the advance or delay of the driver operation with respect to a predetermined steering pattern based on the output of the steering amount detecting means;
Based on the result of comparing the steering feature amount with a predetermined target value, the expansion / contraction ratio of the damping force of the front damper provided in the front suspension is relative to the expansion / contraction ratio of the damping force of the rear damper provided in the rear suspension. A variable damper control device comprising: damping force changing means for changing damping force characteristics of at least one of the front damper and the rear damper so as to change to The variable damper control device according to claim 1, wherein the target value is obtained by smoothing the steering feature amount mapped for each different vehicle speed and steering operation amount. The variable damper control device according to claim 1, wherein the target value is a preset constant.

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