JP2009179089A - Control device for damping-force variable damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a damping-force variable damper that achieves improvement in riding comfort during traveling or the like on an irregular road. <P>SOLUTION: A roll control part 58 is configured to provide the following parts to each wheel, that is, a base-value setting part 61, which sets a target damping-force base value DB on the basis of a vehicle speed v inputted from a vehicle-speed sensor 9, lateral acceleration GY inputted from a lateral G sensor 10, and a yaw rate YR inputted from a yaw-rate sensor 12, a phase compensation part 62 for executing phase compensation to vertical acceleration GH inputted from a vertical G sensor 14 on the wheel side, a correction-value setting part 63 for setting a damping-force correction value DC on the basis of the vertical acceleration GH subjected to the phase compensation, and a target damping-force calculation part 64 for calculating a roll control target value Dr by subtracting the damping-force correction value DC from the target damping-force base value DB. In addition, the correction-value setting part 63 is composed of a gain multiplication part or the like that multiplies the vertical acceleration GH by a prescribed control gain. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a damping force variable damper, and more particularly to a technique for improving riding comfort when traveling on rough roads.

2. Description of the Related Art In recent years, various types of cylindrical dampers used in automobile suspensions have been developed that can control the damping force stepwise or steplessly in order to improve ride comfort and handling stability. For vehicles equipped with a variable damping force damper (hereinafter simply referred to as a damper), it is possible to improve steering stability and ride comfort by variably controlling the damping force of the damper according to the running state of the vehicle. Become. For example, when the vehicle is turning, the vehicle body rolls in the left-right direction due to inertial force (lateral acceleration) that accompanies lateral movement, but the vehicle body becomes excessively large by increasing the target damping force of the damper according to the differential value of the lateral acceleration. Rolls can be suppressed. Also, when traveling on rough roads with continuous small irregularities, the wheels move up and down in a short cycle, but by lowering the target damping force of the damper according to the stroke speed of the damper, the wheel moves up and down. Transmission to the vehicle body can be suppressed (that is, push-up through the suspension can be performed) (see Patent Document 1).
JP 2006-69527 A

  However, in the damping force control method of Patent Document 1, when the differential value of the lateral acceleration is large (that is, the target damping force is high) during slalom running or the like, the damper telescopically moves even if the road surface is uneven. This makes it difficult to reduce the damping force in accordance with the stroke speed (that is, there is no need to push up), resulting in a problem that the ride quality deteriorates. Therefore, the present inventors installed a vertical G sensor for detecting vertical acceleration in a vehicle body (for example, a wheel house of each wheel) in order to surely perform push-up control when the target damping force is high. A method for reducing the damping force of each damper according to the detection result of the upper and lower G sensors was examined.

  However, even when this method is adopted, if the driver performs a steering operation or acceleration / deceleration operation during turning, a roll motion or a pitch motion is generated in the vehicle body. was there. In other words, even if vertical acceleration occurs in the vehicle body, the damping force control device cannot determine whether it is due to road surface irregularities, or due to roll motion or pitch motion of the vehicle body. Considering the instability, the damping force could not be reduced.

  Further, the vehicle body moves up and down after the wheels move up and down due to the unevenness of the road surface, and then the up and down movement is transmitted through the suspension (spring and damper). Therefore, even if the damping force control device outputs a control signal for reducing the damping force, if the damper responsiveness is low, it takes time until the damping force is actually reduced, and there is no need to push up. There was a possibility that the ride comfort was deteriorated. Even in the case where the operation response of the damping force variable damper is relatively high, in order to effectively push up, it has been desired to reduce the damping force before the vehicle body actually moves up and down.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a control device for a damping force variable damper that realizes an improvement in riding comfort when traveling on rough roads.

  A first aspect of the invention is a control device for a damping force variable damper used for damping relative vibration between a vehicle body and a wheel, and a base value setting means for setting a target damping force base value based on the motion state of the vehicle body. A motion state quantity detecting means for detecting or estimating a motion state quantity of the wheel, a correction value setting means for setting a damping force correction value based on a detection result of the motion state quantity detecting means, and the target damping force base And target damping force calculating means for calculating a target damping force by subtracting the damping force correction value from the value.

  According to a second aspect of the present invention, in the damping force variable damper control device according to the first aspect of the invention, the motion state quantity is a vertical acceleration of the wheel.

  According to the first invention, for example, even in a situation where the differential value of the lateral acceleration is large (that is, the target damping force base value is high) and the damper is difficult to telescopically move, the amount of motion state of the wheel is reduced by the unevenness of the road surface. If it changes, drive current will increase / decrease so that it may push up, and the deterioration of riding comfort can be suppressed effectively. Further, according to the second invention, the push-up caused by the road surface unevenness is effectively performed.

  Hereinafter, embodiments in which the present invention is applied to a four-wheeled vehicle will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment, FIG. 2 is a longitudinal sectional view of a damper according to the embodiment, and FIG. 3 is a block diagram illustrating a schematic configuration of a damping force control device according to the embodiment. It is.

<< Configuration of Embodiment >>
<Schematic configuration of automobile>
First, a schematic configuration of an automobile according to an embodiment will be described with reference to FIG. In the description, for the four wheels and corresponding members (tires, suspensions, etc.), suffixes indicating front, rear, left and right are attached to the reference numerals (numbers), respectively, so that the wheels 3fl (front left) and wheels 3fr (front right) ), Wheel 3rl (rear left), wheel 3rr (rear right), and the like, and when referring generically, it is denoted as wheel 3 or the like using a symbol without a suffix.

  As shown in FIG. 1, an automobile (vehicle) V includes four wheels 3 on which tires 2 are mounted. Each wheel 3 includes a suspension arm, a spring, an MRF variable damping force variable damper (hereinafter simply referred to as a damper). It is suspended on the vehicle body 1 by a suspension 5 consisting of 4 etc. The vehicle V is provided with an ECU (Electronic Control Unit) 7 and an EPS (Electric Power Steering) 8 which are the control body of the suspension system. In addition, the vehicle V includes a vehicle speed sensor 9 that detects the vehicle speed, a lateral G sensor 10 that detects lateral acceleration, a longitudinal G sensor 11 that detects longitudinal acceleration, a yaw rate sensor 12 that detects yaw rate, and the like installed at appropriate positions on the vehicle body 1. In addition, a stroke sensor 13 for detecting the displacement of the damper 4 and a vertical G sensor (motion state quantity detecting means) 14 for detecting the vertical acceleration of the wheel 3 are provided for each wheel 3. The vertical G sensor 14 is installed on a member (such as a swinging end of a suspension arm or a knuckle) that moves up and down with the wheel 3.

  The ECU 7 includes a microcomputer, ROM, RAM, peripheral circuit, input / output interface, various drivers, and the like, and the damper 4 of each wheel 3 via a communication line (CAN (Controller Area Network in this embodiment)). And each sensor 10-13.

<Damper structure>
As shown in FIG. 2, the damper 4 of the present embodiment is a monotube type (de carvone type), and a cylindrical cylinder tube 21 filled with MRF and an axial direction with respect to the cylinder tube 21. A piston rod 22 that slides, a piston 26 that is attached to the tip of the piston rod 22 and divides the inside of the cylinder tube 21 into an upper oil chamber 24 and a lower oil chamber 25, and a high-pressure gas chamber 27 under the cylinder tube 21. The main components are a defined free piston 28, a cover 29 for preventing dust from adhering to the piston rod 22 and the like, and a bump stop 30 for buffering at the time of full bound.

  The cylinder tube 21 is connected to the upper surface of the trailing arm 35 that is a wheel side member via a bolt 31 that is fitted into the eyepiece 21a at the lower end. The piston rod 22 has a pair of upper and lower bushes 36 and a nut 37, and a stud 22a at the upper end thereof is connected to a damper base (upper part of the wheel house) 38 which is a vehicle body side member.

  As shown in FIG. 3, the piston 26 is provided with an annular communication passage 39 that communicates the upper oil chamber 24 and the lower oil chamber 25, and an MLV coil 40 that is disposed inside the annular communication passage 39. Yes. When an electric current is supplied from the ECU 7 to the MLV coil 40, a magnetic field is applied to the MRF flowing through the annular communication path 39, and the ferromagnetic fine particles form a chain cluster, and the appearance of the MRF passing through the annular communication path 39. The upper viscosity increases.

<Schematic configuration of damper control device>
The ECU 7 includes a damper control device 50 whose schematic configuration is shown in FIG. The damper control device 50 includes an input interface 51 to which the above-described sensors 9 to 14 and the like are connected, and a damping force setting unit that sets a target damping force of each damper 4 based on detection signals input from the sensors 9 to 12 and 14. 52, a drive current generator 53 that generates a drive current to each damper 4 (MLV coil 40) according to the target damping force and the detection result of the stroke sensor 13, and a drive current generated by the drive current generator 53 The output interface 54 is configured to output to each damper 4. The damping force setting unit 52 accommodates a skyhook control unit 56 used for skyhook control, a roll control unit 58 used for roll control, and a pitch control unit 59 used for pitch control. Yes.

<Roll control unit>
As shown in FIG. 4, the roll control unit 58 uses the target damping force based on the vehicle speed v input from the vehicle speed sensor 9, the lateral acceleration GY input from the lateral G sensor 10, and the yaw rate YR input from the yaw rate sensor 12. Based on a base value setting unit (base value setting means) 61 that sets a base value DB, a phase compensation unit 62 that performs phase compensation on the vertical acceleration GH input from the vertical G sensor 14, and a phase compensated vertical acceleration GH. A correction value setting unit (correction value setting means) 63 for setting the damping force correction value DC, and a target damping force calculation unit for calculating the roll control target value Dr by subtracting the damping force correction value DC from the target damping force base value DB. (Target damping force calculation means) 64 is provided for each wheel 3. The correction value setting unit 63 includes a gain multiplication unit that multiplies the vertical acceleration GH by a predetermined control gain.

<< Operation of Embodiment >>
When the automobile starts traveling, the damper control device 50 executes damping force control whose procedure is shown in the flowchart of FIG. 5 at a predetermined processing interval (for example, 2 ms). When the damping force control is started, the damper control device 50 starts from each acceleration of the vehicle body 1 obtained from the lateral G sensor 10, the front / rear G sensor 11, and the vertical G sensor 14 or the vehicle speed sensor 9 in step S 1 of FIG. The motion state of the automobile V is determined based on the input vehicle speed, the steering speed input from a steering angle sensor (not shown), and the like. Next, the damper control device 50 calculates the skyhook control target value Dsh of each damper 4 in step S2 based on the motion state of the vehicle V, calculates the roll control target value Dr of each damper 4 in step S3, In step S4, a pitch control target value Dp for each damper 4 is calculated.

  Next, the damper control device 50 determines whether or not the stroke speed Ss of each damper 4 is a positive value in step S5, and if this determination is Yes (that is, the damper 4 operates to the extension side). In step S6, the target damping force Dtgt having the largest value among the three control target values Dsh, Dr, Dp is set in step S6. Further, when the determination in step S5 is No (that is, when the damper 4 is operating on the contraction side), the damper control device 50 determines the value among the three control target values Dsh, Dr, and Dp in step S7. Is set as the target damping force Dtgt.

  When the target damping force Dtgt is set in step S6 or step S7, the damper control device 50 searches / sets the target current Itgt corresponding to the target damping force Dtgt from the target current map of FIG. 6 in step S8. Next, the damper control device 50 outputs a drive current to the MLV coil 40 of each damper 4 in step S9 based on the target current Itgt set in step S8.

<Calculation of roll control target value>
In the roll controller 58, the roll control target value Dr is calculated according to the procedure described below. In other words, the base value setting unit 61 sets the target damping force base value DB based on the vehicle speed v, the lateral acceleration GY, and the yaw rate YR, and the phase compensation unit 62 and the correction value setting unit 63 perform phase compensation on the vertical acceleration GH. After the damping force correction value DC is set by performing multiplication of the compensation gain or the like, the roll control target value Dr is obtained by subtracting the damping force correction value DC from the target damping force base value DB in the target damping force calculation unit 64. Calculated.

  FIG. 7 is a graph showing a change in drive current during slalom running. The broken line shows the case where the target damping force base value DB is used as it is as the roll control target value Dr (target damping force Dtgt), and the solid line shows the target damping force. The case where the base value DB is corrected by the damping force correction value DC (in the case of the embodiment) is shown. As can be seen from the figure, in the present embodiment, even when the differential value of the lateral acceleration is large (that is, the target damping force base value DB is high) and the damper 4 is difficult to telescopically move, When vertical acceleration is generated, the drive current increases or decreases so as to push up, and the deterioration of riding comfort is effectively suppressed.

  FIG. 8 is a graph showing temporal changes in the vertical accelerations GHfl to GHrr at the respective wheels 3fl to 3rr when traveling on a road surface on which bumps (swell due to culvert) exist, and the solid line indicates the vertical G installed on the wheel 3 side. The case (in the case of the present embodiment) detected by the sensor 14 is shown, and the case where the broken line is detected by the vertical G sensor installed on the vehicle body 1 side (in the case of a conventional device) is shown. As can be seen from this graph, the vertical acceleration detected on the wheel 3 side does not have a delay similar to the vertical acceleration detected on the vehicle body 1 side, and even when a damping force variable damper having low actuation responsiveness is used, It will be done effectively. Also, even if the driver performs steering operation or acceleration / deceleration operation during turning, and the roll motion or pitch motion occurs in the vehicle body, the vertical acceleration on the wheel 3 side is hardly detected when traveling on a flat road, The vehicle posture does not become unstable by reducing the damping force unnecessarily.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, although the above-described embodiment applies the present invention to roll control, it can also be applied to pitch control, bounce control, operation control, and the like. In the above embodiment, the vertical G sensor for detecting the vertical acceleration of the wheel is used as the vertical momentum detecting means. However, the vertical speed sensor for detecting the vertical speed of the wheel is used, or the detection signal of the vertical speed sensor is differentiated. Thus, the vertical acceleration may be obtained. In addition, the specific configuration of the automobile and the control device, the specific control procedure, and the like can be changed as appropriate without departing from the spirit of the present invention.

1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment. It is a longitudinal cross-sectional view of the damper which concerns on embodiment. It is a block diagram which shows schematic structure of the damping-force control apparatus which concerns on embodiment. It is a block diagram which shows schematic structure of the roll control part which concerns on embodiment. It is a flowchart which shows the procedure of damping force control which concerns on embodiment. It is a target current map concerning an embodiment. It is a graph which shows the change of the drive current at the time of slalom running. It is a graph showing the time change of the vertical acceleration in each wheel at the time of bump road driving.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 3 Wheel 4 Damping force variable damper 14 Vertical G sensor (vertical acceleration detection means)
DESCRIPTION OF SYMBOLS 50 Damper control apparatus 52 Damping force setting part 56 Sky hook control part 58 Roll control part 59 Pitch control part 61 Base value setting part (base value setting means)
62 Phase compensation unit 63 Correction value setting unit (correction value setting means)
64 Target damping force calculation unit (target damping force calculation means)
V car

Claims (2)

A control device for a damping force variable damper used for damping relative vibration between a vehicle body and a wheel,
Base value setting means for setting a target damping force base value based on the motion state of the vehicle body;
A motion state quantity detecting means for detecting or estimating a motion state quantity of the wheel;
Correction value setting means for setting a damping force correction value based on the detection result of the motion state quantity detection means;
A damping force variable damper control device comprising: a target damping force calculation means for calculating a target damping force by subtracting the damping force correction value from the target damping force base value.   2. The damping force variable damper control device according to claim 1, wherein the motion state quantity is vertical acceleration of the wheel.

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