JP4621582B2 - Control device for variable damping force damper - Google Patents

Description

  The present invention relates to a control device for a variable damping force damper, and more particularly to a control device for a variable damping force damper for suppressing a pitching motion of a vehicle body during acceleration / deceleration.

  The spring provided in the suspension device of the vehicle is deformed while absorbing the impact, and when the external force is lost, the spring is repelled in a direction to restore the deformation, and as a result, reciprocating vibration is generated. In order to attenuate the vibration energy of the spring, a so-called shock absorber damper is used in combination with the vehicle suspension system. The damping force of the damper is preferably small in order to mitigate the impact, but is preferably somewhat large in order to improve the ground contact property and steering stability of the tire. A variable damping force damper capable of changing the damping force is known as one that can satisfy the contradictory conditions (see Patent Document 1).

On the other hand, when a braking force is applied to the wheel during traveling, the vehicle body is lowered forward (nose dive), and when a driving force is applied to the wheel, the vehicle body is raised forward (nose lift). It is known to control the damping force of the damper based on the value of acceleration / deceleration in order to suppress the posture change when such longitudinal acceleration / deceleration acts on the vehicle (see Patent Document 2). Wanna)
JP-A-60-113711 JP 09-309314 A

  However, if the damping force of the damper is controlled based on the value obtained by processing the longitudinal acceleration / deceleration with the differential filter, high responsiveness can be obtained.However, due to the characteristics of the differential filter, for example, the accelerator pedal is suddenly released from the acceleration state. In some cases, an error may occur such that the loss of acceleration at the time of braking is regarded as the occurrence of deceleration, or the loss of deceleration at the time of sudden braking stop is regarded as the occurrence of acceleration.

  For this reason, in the case of sudden braking, for example, when a deceleration is detected when braking is started, the damping force of the front wheel damper is increased to suppress the nose dive and the front wheel struts are strengthened. Although it is desired to return the control gain of the damping force to normal when stopped, the damping force of the damper remains high because the control corresponding to the acceleration is applied at the moment when the deceleration disappears. Moreover, although the posture control mode is different between braking and acceleration, it is executed erroneously, which gives a great discomfort to the occupant. Moreover, the fact that such unnecessary damping force control is added also leads to waste of power, particularly in the case of a damping force variable damper using a magnetorheological fluid as described in Document 1.

  The present invention has been devised to cope with such disadvantages of the prior art, and its main purpose is to achieve an appropriate pitch rigidity when a longitudinal acceleration / deceleration is applied without impairing high responsiveness. Another object of the present invention is to provide an improved variable damping force damper control device that can be obtained and that prevents an erroneous damping force control from being applied at the end of acceleration / deceleration.

In order to solve such a problem, the present invention provides a control of a variable damping force damper for controlling a damping force of a damper used in a vehicle suspension device with a target value corresponding to a differential value of a longitudinal acceleration / deceleration of the vehicle. A device for detecting an operation state of the brake pedal and a means for detecting the vehicle speed, and when the vehicle front-rear acceleration / deceleration is detected, the brake pedal is operated in a state where the vehicle speed is a predetermined value or less. When detected, the damping force control corresponding to the acceleration is not applied, and only the control corresponding to the braking is applied. Further, in the present invention, when the operation of the brake pedal is not detected when the longitudinal acceleration / deceleration is detected, the target value corresponding to the deceleration of the damping force is set lower than usual. Features. Further, the present invention includes a longitudinal acceleration / deceleration sensor for detecting the longitudinal acceleration / deceleration, and the differential value of the longitudinal acceleration / deceleration of the vehicle passes the longitudinal acceleration / deceleration value detected by the longitudinal acceleration / deceleration sensor through a low-pass filter. Further, the target value of the damping force is set based on the differential value of the longitudinal acceleration / deceleration of the vehicle, which is acquired by passing through a differential filter.

According to the present invention as described above, it is possible to prevent the longitudinal vibration of the vehicle body due to the tension of the damper immediately after stopping. Further, it is possible to prevent the front wheel dampers from becoming excessively hard when the throttle is turned off immediately after sudden acceleration. That is, according to the present invention, it is possible to prevent unnatural vehicle behavior due to differential control errors while maintaining high responsiveness by using differential control, so that steering stability and ride comfort are at a high level. It is possible to achieve a great effect in achieving both.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an example of a basic configuration of an automobile suspension device that supports front, rear, left, and right wheels of a four-wheel automobile on a vehicle body. The suspension device 1 includes a knuckle 3 that supports a tire 2, upper and lower suspension arms 4 U and 4 L that support the knuckle 3 with respect to the vehicle body 5, and a lower suspension arm 4 L and the vehicle body 5 in parallel. The compression coil spring 6 and the hydraulic damper 7 are provided.

  As the hydraulic damper 7, for example, a variable damping force damper formed by enclosing MRF (Magneto-Rheological Fluid) is used. The damper 7 controls the current applied to an MLV (Magnetizable Liquid Valve) provided in the piston, thereby allowing MRF to flow between the piston upper chamber and the piston lower chamber via an orifice provided in the piston. The damping force can be continuously changed by changing the apparent viscosity (see Patent Document 1).

  The damping force of the damper 7 is stored in an electronic control unit (ECU) 16 based on outputs of the vehicle speed sensor 11, the longitudinal acceleration sensor 12, the vertical acceleration sensor 13, the brake pedal sensor 14, the damper stroke sensor 15,. The control target value is calculated by the calculated arithmetic unit, and the vehicle behavior at that time is controlled to be optimum.

  More specifically, as shown in FIG. 2, the longitudinal acceleration value of the vehicle detected by the longitudinal acceleration sensor 12 passes through the low-pass filter 21, so that the acceleration (deceleration) speed caused by the speed change during normal traveling is obtained. The value is removed. The acceleration (deceleration) value generated by the depression of the accelerator pedal or the brake pedal that has passed through the low-pass filter 21 passes through the differentiation filter 22 and is time-differentiated. The differential value of the acceleration (deceleration) is multiplied by a gain obtained by searching a gain map 23 set in advance based on the vehicle speed, and is output as a control target value of the damping force.

  Next, the point of damping force control according to the present invention will be described with reference to FIGS.

  In FIG. 3, if the occurrence of deceleration is detected from the output of the longitudinal acceleration sensor 12 (step 1), the output of the brake pedal sensor 14 is confirmed to determine whether or not the brake pedal is operated (step 2).

  If it is determined that the brake pedal is not depressed, it is determined that the acceleration has disappeared due to throttle-off or the like, and the gain multiplied by the control target value of the damping force during deceleration is reduced, and the damper becomes excessively hard. Is prevented (step 3). If it is detected that the brake pedal is depressed, it is determined that the braking operation is performed by the driver's will, and the nose dive is suppressed by applying damping force control corresponding to the time of braking ( Step 4).

  With the above processing, unnecessary damping force control is prevented from being applied even when the disappearance of acceleration when the accelerator pedal is suddenly released from the acceleration state is erroneously recognized as the occurrence of deceleration.

  In FIG. 4, when the longitudinal acceleration sensor 12 detects the occurrence of deceleration (step 11), it is confirmed whether or not the current vehicle speed is equal to or lower than the predetermined vehicle speed (step 12), and is determined to be equal to or lower than the predetermined vehicle speed. At the time, the output of the brake pedal sensor is confirmed to determine whether or not the brake pedal is operated (step 13). When the vehicle speed is below a predetermined speed and the operation of the brake pedal is detected, the control circuit corresponding to the time of braking is applied by blocking the acceleration control circuit so that the control corresponding to the time of acceleration is not performed. (Step 14).

  On the other hand, if it is determined in step 12 that the vehicle speed is equal to or higher than the predetermined vehicle speed, or if it is determined in step 13 that the brake pedal is not operated, the normal control mode is selected, and the acceleration (deceleration) value at that time is selected. The damping force is controlled according to (step 15).

  The above processing prevents unnecessary damping force control from being applied even when the disappearance of deceleration at the time of sudden braking stop is regarded as the occurrence of acceleration.

  In applying the present invention, the structure of the damping force varying means is not particularly limited, and can be implemented by switching the area of the mechanical orifice by, for example, a rotary valve. The concept of the present invention can be applied not only to a passive control suspension device but also to an active control suspension device in which the functions of a coil spring and a damper are replaced with hydraulic actuators.

It is a lineblock diagram of one wheel of a suspension device to which the present invention is applied. It is a block diagram of the control law of this invention. It is a control flow figure by this invention. It is a 2nd control flow figure by this invention.

Explanation of symbols

1 Suspension device 7 Damper 11 Vehicle speed sensor 12 Longitudinal acceleration sensor 14 Brake pedal sensor 16 ECU

Claims (3)

A control device for a variable damping force damper for controlling a damping force of a damper used in a vehicle suspension device by a target value corresponding to a differential value of a longitudinal acceleration / deceleration of the vehicle ,
Means for detecting the operating state of the brake pedal, and means for detecting the vehicle speed,
If the operation of the brake pedal is detected when the vehicle speed is below the specified value when the longitudinal acceleration / deceleration of the vehicle is detected, the damping force control corresponding to acceleration is not applied, and the control corresponding to braking is not applied. A control device for a variable damping force damper, characterized in that only is added. The target value corresponding to the time of deceleration of the damping force is set lower than usual when the operation of the brake pedal is not detected when the longitudinal acceleration / deceleration is detected. The control device of the variable damping force damper according to 1. A front / rear acceleration / deceleration sensor for detecting the front / rear acceleration / deceleration;
The differential value of the longitudinal acceleration / deceleration of the vehicle is obtained by passing the longitudinal acceleration / deceleration detected by the longitudinal acceleration / deceleration sensor through a low-pass filter and further passing through a differential filter. 3. The variable damping force damper control device according to claim 1, wherein a target value of the damping force is set based on the value .

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