JP2008238922A - Control device of damping force variable damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a damping force variable damper, which enhances ride comfort when a vehicle makes a slalom travel on an irregular passage. <P>SOLUTION: A target current generation unit 53 calculates the virtual damping force Dvirt by multiplying the reduction coefficient to the target damping force Dtgt in Step S16. Next, the target current generation unit 53 retrieves/sets the virtual reference current Ivref from the target current map based on the virtual damping force Dvirt and the reference stroke speed Sr in Step S17, and retrieves/sets the virtual target current Ivtgt from the target current map based on the virtual damping force Dvirt and the actual stroke speed Ss in Step S18. Next, the target current generation unit 53 calculates the corrective current Icorr by multiplying the predetermined restoration coefficient to the value of the virtual target current Ivtgt subtracted from the virtual reference current Ivref in Step S19. Thereafter, the target current Itgt is calculated by subtracting the corrective current Icorr from the basic target current Ibase in Step S20. <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 realizing an improvement in riding comfort during slalom traveling on an irregular road.

  2. Description of the Related Art In recent years, various types of cylindrical dampers used for automobile suspensions have been developed in order to improve the ride comfort and steering stability. As the damping force control mechanism of the damping force variable damper, a mechanical control type that increases or decreases the flow area of the orifice by using a motor, a solenoid or the like is generally used, but a magnetic fluid or a magnetorheological fluid is used as a working fluid. The current control type that increases or decreases the current applied to the magnetic fluid valve has appeared.

In an automobile equipped with a current control type damping force variable damper (hereinafter simply referred to as a damper), the control current of the damper is variably controlled within a predetermined range (for example, 0A to 5A) according to the running state. The damping force is increased or decreased as appropriate to improve handling stability and riding comfort (see Patent Document 1). For example, when turning, the body rolls in the left-right direction due to the inertial force (lateral acceleration) that accompanies lateral movement. To suppress excessive roll of the car body at this time, the control current is set according to the differential value of the lateral acceleration. Increase the damping force of the damper. Also, when traveling on rough roads with continuous small irregularities, the wheel moves up and down in a short cycle, but in order to suppress transmission of the vertical movement of the wheel to the vehicle body (i.e., pushing up through the suspension) Therefore, the damping force of the damper is lowered by reducing the control current according to the actual stroke speed of the damper.
JP 2006-69527 A

  However, in the control method described above, when the differential value of the lateral acceleration becomes higher than a certain level during slalom running or the like, the control current is fixed at the upper limit of 5 A regardless of increase or decrease of the actual stroke speed (sticking). ) In this case, there is a problem that even if thrust due to irregular roads is raised, the damping force is so high that the damper is difficult to telescopically move, and thrusting is no longer performed and riding comfort is deteriorated.

  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 an irregular road on a slalom.

  The invention according to claim 1 is a control device for controlling a damping force variable damper provided for suspension of a vehicle body, and sets a target damping force of the damping force variable damper based on a motion state quantity of the vehicle body. A basic control amount setting means for setting a basic control amount of the damping force variable damper based on a force setting means, a setting result of the target damping force setting means and an actual stroke speed of the damping force variable damper; High attenuation determination means for determining whether or not the target damping force exceeds a predetermined high attenuation determination threshold; virtual damping force calculation means for calculating a virtual damping force by multiplying the target damping force by a predetermined reduction coefficient; Based on the virtual damping force and the actual stroke speed of the damping force variable damper, a virtual target control amount setting means for setting a virtual target control amount of the damping force variable damper, and based on the virtual target control amount When it is determined by the correction control amount calculation means for calculating the correction control amount and the high attenuation determination means that the target damping force exceeds a predetermined high attenuation determination threshold, the correction control amount is subtracted from the basic control amount. And a target control amount calculating means for calculating the target control amount.

  According to a second aspect of the present invention, in the damping force variable damper control device according to the first aspect, the virtual normative control amount of the variable damping force damper is based on the virtual damping force and a predetermined normative stroke speed. Further comprising a virtual reference control amount setting means for setting the correction control amount by multiplying a value obtained by subtracting the virtual target control amount from the virtual reference control amount by a predetermined restoration coefficient. It is characterized by calculating.

  According to the first aspect of the present invention, for example, even when the target damping force becomes high during slalom traveling or the like, the target current (that is, the damping force) increases or decreases according to the increase or decrease of the actual stroke speed. The push-up due to the unevenness is effectively performed, and the deterioration of the ride comfort is suppressed. According to the second aspect of the present invention, the correction control amount can be calculated by a relatively simple arithmetic process, so that the cost of the control device can be reduced and the processing speed can be improved.

  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. FIG. 4 is a block diagram illustrating a schematic configuration of the target current generation unit according to the embodiment.

<< 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 members arranged for them, that is, tires, suspensions, and the like, suffixes indicating front, rear, left, and right are attached to the reference numerals, for example, wheel 3fl (front left), wheel 3fr (front right), wheel 3rl (rear left), wheel 3rr (rear right) and collectively referred to as wheel 3, for example.

  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 damping force 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. Further, the vehicle V includes a vehicle speed sensor 9 for detecting the vehicle speed, a lateral G sensor 10 for detecting lateral acceleration, a longitudinal G sensor 11 for detecting longitudinal acceleration, a yaw rate sensor 12 for detecting yaw rate, and the like installed at appropriate positions on the vehicle body 1. In addition, a stroke sensor 13 for detecting the actual stroke speed Ss of the damper 4 and a vertical G sensor (vertical momentum detecting means) 14 for detecting vertical acceleration in the vicinity of the wheel house are provided for each 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 9-14.

<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 is a damping force setting that sets the target damping force Dtgt of each damper 4 based on the input interface 51 to which the above-described sensors 9 to 14 and the like are connected and the detection signals input from the sensors 9 to 12 and 14 etc. Unit 52, a target current generating unit 53 that generates a target current Itgt to each damper 4 (MLV coil 40) according to the target damping force Dtgt and the actual stroke speed Ss, and a drive current from the target current generating unit 53 The output interface 54 is configured to output to each damper 4. The damping force setting unit 52 of the present embodiment includes a skyhook control unit 56 used for skyhook control, a roll control unit 58 used for roll control, and a pitch control unit used for pitch control. 59 are accommodated.

<Target current generator>
As shown in FIG. 4, the target current generation unit 53 includes a damping force determination unit 61 that determines the type and magnitude of the target damping force Dtgt input from the damping force setting unit 52, the target damping force Dtgt, and the actual stroke speed Ss. A basic target current setting unit 62 that sets the basic target current Ibase, a virtual damping force calculation unit 63 that calculates a virtual damping force Dvirt by multiplying the target damping force Dtgt by a predetermined reduction factor, and a virtual damping force Dvirt A virtual reference current setting unit 64 that sets a virtual reference current Ivref based on the reference stroke speed Sr and the reference stroke speed Sr (the direction is the same as the actual stroke speed Ss and a relatively small speed), a virtual damping force Dvirt, and an actual stroke speed Ss. A virtual target current setting unit 65 for setting the virtual target current Ivtgt based on the virtual reference current Ivref and the virtual target current Ivtgt. A correction control amount calculation unit 66 that calculates a correction current Icorr by multiplying the predetermined target coefficient by a predetermined restoration coefficient, and a target control amount calculation unit 67 that calculates a target current Itgt by subtracting the correction current Icorr from the basic target current Ibase. It is provided for each wheel 3. The target control amount calculation unit 67 switches execution / non-execution of the subtraction process based on a command from the damping force determination unit 61.

<< Operation of Embodiment >>
<Target damping force setting process>
When the vehicle starts traveling, the damper control device 50 executes a target damping force setting process whose procedure is shown in the flowchart of FIG. 5 at a damping process setting unit 52 with a predetermined processing interval (for example, 2 ms). When the damping force setting unit 52 starts the target damping force setting process, first, in step S1 of FIG. 5, each acceleration of the vehicle body 1 obtained from the lateral G sensor 10, the longitudinal G sensor 11, and the vertical G sensor 14, The motion state of the vehicle V is determined based on the vehicle speed input from the vehicle speed sensor (not shown), the steering speed input from the steering angle sensor (not shown), and the like. Next, the damping force setting unit 52 calculates the skyhook control target value Dsh of each damper 4 in step S2 based on the motion state of the vehicle V, and calculates the roll control target value Dr of each damper 4 in step S3. In step S4, the pitch control target value Dp of each damper 4 is calculated.

  Next, the damping force setting unit 52 determines whether or not the actual stroke speed Ss of each damper 4 is a positive value in step S5. If this determination is Yes (that is, the damper 4 is on the extension side). In step S6, the largest one of the three control target values Dsh, Dr, Dp is set as the target damping force Dtgt. In step S7, the target current generating unit 53 is set to the target damping force Dtgt. Is output. In addition, when the determination in step S5 is No (that is, when the damper 4 is operating on the contraction side), the damping force setting unit 52 determines that among the three control target values Dsh, Dr, and Dp in step S8. The smallest value is set as the target damping force Dtgt, and the target damping force Dtgt is output to the target current generating unit 53 in step S7.

<Target current generation processing>
The damper control device 50 according to the present embodiment executes target current generation processing whose procedure is shown in the flowchart of FIG. 6 in the target current generation unit 53 in parallel with the above-described damping force control. When the target current generating unit 53 starts the target current generating process, first, in step S11 of FIG. 5, the basic target current Ibase (FIG. 8) corresponding to the target damping force Dtgt and the actual stroke speed Ss is obtained from the target current map of FIG. ). As can be seen from FIG. 8, the basic target current Ibase has several sticking points at the upper limit (5A).

  Next, the target current generator 53 determines whether or not the target damping force Dtgt is the roll control target value Dr in step S12. If this determination is No, the target current generator Ibase is set to the basic target current Ibase in step S13. As the current Itgt, a drive current corresponding to the target current Itgt is output to the MLV coil 40 of each damper 4 in step S14.

  On the other hand, if the target damping force Dtgt is the roll control target value Dr and the determination in step S12 is Yes, the target current generating unit 53 determines that the target damping force Dtgt is a predetermined high attenuation determination threshold Dth (eg, in step S15). 4,000 N), and if this determination is No, the basic target current Ibase is set as the target current Itgt in step S13, and the drive current corresponding to the target current Itgt is determined in step S14. Output to the MLV coil 40 of each damper 4.

  If the target damping force Dtgt exceeds the high damping determination threshold value Dth and the determination in step S15 is also Yes, the target current generating unit 53 reduces the target damping force Dtgt to a reduction coefficient (0.3 in this embodiment) in step S16. ) To calculate the virtual damping force Dvirt. Next, the target current generation unit 53 searches / sets the virtual reference current Ivref from the target current map based on the virtual damping force Dvirt and the reference stroke speed Sr in step S17 (FIG. 9), and virtually attenuates in step S18. The virtual target current Ivtgt is searched / set from the target current map based on the force Dvirt and the actual stroke speed Ss (FIG. 10).

  Next, in step S19, the target current generation unit 53 multiplies the value obtained by subtracting the virtual target current Ivtgt from the virtual reference current Ivref by a predetermined restoration coefficient (1.3 in the present embodiment) to obtain the correction current Icorr. Calculate (FIG. 11). Next, the target current generation unit 53 calculates the target current Itgt by subtracting the correction current Icorr from the basic target current Ibase in step S20 (FIG. 12), and then in step S14, calculates the drive current corresponding to the target current Itgt. Output to the MLV coil 40 of the damper 4.

  In the present embodiment, by adopting such a configuration, as shown in FIG. 12, even when the target damping force becomes high during slalom running or the like, the target current Itgt according to the increase / decrease of the actual stroke speed Ss. (In other words, since the damping force) increases and decreases, the road surface is effectively pushed up by the unevenness of the road surface, and the deterioration of riding comfort is suppressed.

  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, safety control, and the like. In the above embodiment, the present invention is applied to a damping force variable damper using MRF as a working fluid. However, the present invention includes other current control type damping force variable dampers and mechanically controlled damping force variable dampers. It is also applicable to. Further, the reduction coefficient and the restoration coefficient are not limited to the values shown in the embodiment, and it is desirable to adopt optimum values through experiments, simulations, and the like. 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 the target damping force setting process which concerns on embodiment. It is a flowchart which shows the procedure of the target electric current production | generation process which concerns on embodiment. It is a target current map concerning an embodiment. It is a graph which shows the change of the basic target current concerning an embodiment. It is a graph which shows the change of the virtual normative current concerning an embodiment. It is a graph which shows the change of the virtual target current concerning an embodiment. It is a graph which shows the change of the correction current concerning an embodiment. It is a graph which shows the change of the target current concerning an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 3 Wheel 4 Damper 13 Stroke sensor 50 Damper control apparatus 52 Damping force setting part (Target damping force setting means)
53 Target Current Generation Unit 61 Damping Force Judgment Unit (High Damping Judgment Unit)
62 Basic target current setting section (basic control amount setting means)
63 Virtual damping force calculation unit (virtual damping force calculation means)
64 Virtual normative current setting unit (virtual normative control amount setting means)
65 Virtual target current setting unit (virtual target control amount setting means)
66 Correction control amount calculation unit (correction control amount calculation means)
67 Target control amount calculation unit (target control amount calculation means)
V car

Claims (2)

A control device for controlling a damping force variable damper provided for suspension of a vehicle body,
A target damping force setting means for setting a target damping force of the damping force variable damper based on the motion state quantity of the vehicle body;
A basic control amount setting means for setting a basic control amount of the damping force variable damper based on a setting result of the target damping force setting means and an actual stroke speed of the damping force variable damper;
High attenuation determination means for determining whether or not the target damping force exceeds a predetermined high attenuation determination threshold;
Virtual damping force calculating means for calculating a virtual damping force by multiplying the target damping force by a predetermined reduction coefficient;
Virtual target control amount setting means for setting a virtual target control amount of the damping force variable damper based on the virtual damping force and the actual stroke speed of the damping force variable damper;
Correction control amount calculation means for calculating a correction control amount based on the virtual target control amount;
A target control amount calculating means for calculating a target control amount by subtracting the correction control amount from the basic control amount when the high damping determination means determines that the target damping force exceeds a predetermined high attenuation determination threshold; A damping force variable damper control device comprising: Further comprising virtual reference control amount setting means for setting a virtual reference control amount of the damping force variable damper based on the virtual damping force and a predetermined reference stroke speed;
2. The correction control amount calculation unit according to claim 1, wherein the correction control amount calculation unit calculates the correction control amount by multiplying a value obtained by subtracting the virtual target control amount from the virtual reference control amount by a predetermined restoration coefficient. Control device for the damping force variable damper.

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