JP5090963B2 - Control device and control method for damping force variable damper - Google Patents

Description

  The present invention relates to a control device and a control method for a damping force variable damper, and more particularly to a technique for improving riding comfort and suppressing tire skidding during turning.

  As a cylindrical damper used for a suspension of a four-wheeled vehicle, various types of damping force variable types capable of variably controlling the damping force stepwise or steplessly have been developed in order to improve ride comfort and handling stability. In an automobile 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 its running state. . For example, when the vehicle turns, the vehicle body rolls in the left-right direction due to inertial force (lateral acceleration) that accompanies lateral movement, while calculating the first roll target damping force according to the differential value of the lateral acceleration, The second roll target damping force is calculated according to the second-order differential value of the yaw rate, and the damping force control is performed based on the larger one of the first and second roll target damping forces. It has been proposed (see Patent Document 1). Further, there has been proposed a method in which a roll target damping force is set based on a differential value of longitudinal acceleration or lateral acceleration of a vehicle body, and then the roll target damping force is corrected by an unsprung speed or a damper load (patent) Reference 2).

JP 2007-153186 A JP 2006-69527 A

  However, the methods of Patent Documents 1 and 2 have the following problems in terms of ride comfort and handling stability because the roll target damping force of all the wheels is set to the same value. That is, if the roll target damping force of all the wheels is set high during turning of the automobile, it becomes difficult to push up from the road surface (a phenomenon in which the vertical movement of the wheels is transmitted to the vehicle body via the suspension). Ride comfort is reduced. Further, when the roll target damping force of all the wheels is set to be high, the moving speed of the load between the wheels becomes high. Therefore, as shown in FIG. 13, a transiently large load Lfr, Lrr is applied. Therefore, when the cornering power generated by the tires of the turning outer wheels 3fr and 3rr with increased load is saturated when the friction coefficient of the road surface is small, the tires of the turning inner wheels 3fl and 3rl and the tires of the turning outer wheels 3fr and 3rr are saturated. There was a risk that the average cornering power would decrease and the skid of the tire would occur. In addition, as shown in the load-cornering power diagram of FIG. 14, the cornering power shows an upwardly convex change with respect to the load. Therefore, the smaller the difference between the load on the turning inner ring side and the load on the turning outer ring side, High average cornering power is obtained.

  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 and a control method for a damping force variable damper that realizes improvement in riding comfort and suppression of tire skidding during turning. .

  A first invention is a control device mounted on a vehicle in which a damping force variable damper is interposed between a vehicle body and each wheel, and used for damping force control of the damping force variable damper. And a roll target damping force setting unit for individually setting a roll target damping force of each damping force variable damper based on a detection result of the turning state amount detection unit. The roll target damping force setting means reduces the roll target damping force other than the side of the turning inner front wheel when the vehicle is in a turning traveling state.

  The second aspect of the invention is the damping force variable damper control device according to the first aspect of the invention, further comprising wheel slip state detecting means for detecting a slip state of each wheel, wherein the roll target damping force setting means is the Only when it is detected by the wheel slip state detecting means that one of the wheels is slipping, the roll target damping force other than that on the turning inner front wheel side is reduced.

The third invention is a control method of the variable damping force damper which is subjected to the suspension of the vehicle, the processing for detecting the turning state of the vehicle, based on the turning state quantity, the damping force variable damper A roll target damping force other than the inside wheel on the inside of the turn when it is determined that the vehicle is in a turning traveling state, and a process for determining whether or not the vehicle is in a turning traveling state. And a process for reducing the force.

  According to the first aspect of the invention, since the roll target damping force other than the turning inner front wheel is reduced during turning, it is easy to push up from the road surface, and a good riding comfort can be ensured. Further, since the difference between the load on the turning outer wheel and the load on the turning inner wheel at the time of transition is reduced, a larger average cornering power can be obtained and the side skid of the tire can be effectively suppressed. In addition, according to the second invention, the roll target damping force other than the turning inner front wheel is reduced only when the wheel slips, so that the riding comfort can be further improved. In addition, according to the third aspect of the present invention, the roll target damping force other than the turning inner front wheel is reduced during turning, so that it is easy to push up from the road surface, and good riding comfort can be ensured. . Further, since the difference between the load on the turning outer wheel and the load on the turning inner wheel at the time of transition is reduced, a larger average cornering power can be obtained and the side skid of the tire can be effectively suppressed.

  Hereinafter, two embodiments in which the present invention is applied to a four-wheeled vehicle will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a four-wheel vehicle according to the first embodiment, FIG. 2 is a longitudinal sectional view of a damper according to the first embodiment, and FIG. 3 is a diagram of the damping force control device according to the first embodiment. FIG. 4 is a block diagram illustrating a schematic configuration, and FIG. 4 is a block diagram illustrating a schematic configuration of a roll calculation control unit according to the first embodiment.

<Schematic configuration of automobile>
First, a schematic configuration of the automobile according to the first 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, a vehicle body 1 of an automobile (vehicle) V has wheels 3 with tires 2 mounted on the front, rear, left and right thereof. These wheels 3 are each provided with a suspension arm 4, a spring 5, and a variable damping force. It is suspended from the vehicle body 1 by a suspension 7 composed of a type damper (hereinafter simply referred to as a damper) 6 or the like. In the vehicle V, in addition to an ECU (Electronic Control Unit) 8 used for various controls, a vehicle speed sensor 9, a lateral G sensor 10, a front / rear G sensor 11, a yaw rate sensor 12, and the like are installed at appropriate positions of the vehicle body 1. . In the vehicle V, a vertical G sensor (sprung acceleration detection means) 13, a stroke sensor (state quantity detection means) 14, and a wheel speed sensor 15 are installed for each of the wheels 3fl to 3rr.

  The ECU 8 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like. Each of the wheels 3 is connected via a communication line (CAN (Controller Area Network) in the first embodiment). The damper 6 and the sensors 9 to 15 are connected.

<Damper>
As shown in FIG. 2, the damper 6 of the first embodiment is a monotube type (de carvone type), and a cylindrical cylinder 22 filled with MRF (Magneto-Rheological Fluid), A piston rod 23 that slides in the axial direction with respect to the cylinder 22, a piston 26 that is attached to the tip of the piston rod 23 and divides the inside of the cylinder 22 into an upper oil chamber 24 and a lower oil chamber 25, The main components are a free piston 28 that defines a high-pressure gas chamber 27 in the lower portion, a cover 29 that prevents dust from adhering to the piston rod 23 and the like, and a bump stop 30 that performs buffering during full bouncing.

  The cylinder 22 is connected to the upper surface of the suspension arm 4 that is a wheel side member via a bolt 31 that is fitted into the eyepiece 22a at the lower end. The piston rod 23 is connected to a damper base (wheel house upper part) 34 that is a vehicle body side member via a pair of upper and lower rubber bushes 32 and a nut 33.

  The piston 26 is provided with a communication passage 41 that allows the upper oil chamber 24 and the lower oil chamber 25 to communicate with each other, and an MLV coil 42 that is positioned inside the communication passage 41. When a current is supplied from the ECU 8 to the MLV coil 42, a magnetic field is applied to the MRF flowing through the communication path 41, and the ferromagnetic fine particles form a chain cluster. As a result, the apparent viscosity of the MRF passing through the communication passage 41 (hereinafter simply referred to as viscosity) increases, and the damping force of the damper 6 increases.

<Schematic configuration of damping force control device>
As shown in FIG. 3, the ECU 8 includes a damping force control device 50 that controls the damper 6. The damping force control device 50 includes the input interface 51 to which the above-described sensors 9 to 15 are connected, the roll moment, the pitch moment, the sprung speed, and the like obtained from the detection signals of the sensors 9 to 15. A driving current to each damper 6 (MLV coil 42) according to the damping force setting unit 52 for setting the target damping force, the target damping force input from the damping force setting unit 52, and the stroke speed Ss input from the stroke sensor 14. The drive current generator 53 generates the drive current, and the output interface 54 outputs the drive current generated by the drive current generator 53 to each damper 6. The damping force setting unit 52 includes a skyhook calculation control unit 55 used for skyhook control, a roll calculation control unit 56 used for roll control, a pitch calculation control unit 57 used for pitch control, and the like. Contained.

<Roll calculation control unit>
As shown in FIG. 4, the roll calculation control unit 56 sets the first base value Drb1 based on the lateral acceleration Gy and the second base value Drb2 based on the yaw rate γ. A second base value setting unit 62, a roll base value setting unit 63 for selecting / setting the larger one of the first base value Drb1 and the second base value Drb2 as the roll damping force base value Drbase, and lateral acceleration Based on the turning direction determination unit 64 that determines the turning direction based on Gy, the setting result of the roll base value setting unit 63, and the determination result of the turning direction determination unit 64, roll target damping forces Drtfl to Drtrr for each wheel 3 are calculated. A roll target damping force setting unit 65 for setting / outputting is provided.

<< Operation of First Embodiment >>
<Damping force control>
When the vehicle V starts traveling, the damping force control device 50 repeatedly executes damping force control whose procedure is shown in the flowchart of FIG. 5 at a predetermined processing interval (for example, 10 ms). When the damping force control is started, the damping force control device 50 detects each acceleration of the vehicle body 1 obtained from the lateral G sensor 10, the front and rear G sensor 11, and the vertical G sensor 13 in step S1 of FIG. The motion state of the automobile V is determined based on the vehicle speed or the like input from (not shown). Next, the damping force control device 50 sets the skyhook target damping force Dshgt in step S2 based on the motion state of the vehicle V, and the roll target damping force Drtgt (Drtfl to Drtrr) of each damper 6 in step S3. In step S4, the pitch target damping force Dptgt is set.

  Next, the damping force control device 50 determines whether or not the stroke speed Ss of each damper 6 is a positive value in step S5, and if this determination is Yes (that is, the damper 6 is on the extension side). In operation S6, the largest one of the three target damping forces Dshgt, Drtgt, Dptgt is adopted as the target damping force Dtgt in step S6. In addition, when the determination in step S5 is No (that is, when the damper 6 is operating on the contraction side), the damping force control device 50 determines that among the three target damping forces Dshgt, Drtgt, and Dptgt in step S7. The smallest value is adopted as the target damping force Dtgt.

  When the target damping force value Dtgt is determined in step S6 or step S7, the damping force control device 50 searches / sets the target current Itgt corresponding to the target damping force Dtgt and the stroke speed Ss from the target current map of FIG. 6 in step S8. After that, a drive current is output to the MLV coil 46 of each damper 6 in step S9.

<Roll target damping force setting process>
In parallel with the damping force control described above, the roll calculation control unit 56 in the damping force control device 50 repeatedly executes a roll target damping force setting process whose procedure is shown in the flowchart of FIG. 7 at a predetermined processing interval. When the roll target value setting process is started, the roll calculation control unit 56 calculates a differential value (hereinafter referred to as a lateral acceleration differential value) Gy ′ of the lateral acceleration Gy input from the lateral G sensor 10 in step S21 of FIG. In step S22, the first base value Drb1 is retrieved / set using the lateral acceleration-damping force map of FIG.

  Next, in step S23, the roll calculation control unit 56 performs second-order differentiation on the yaw rate γ input from the yaw rate sensor 12 to calculate the yaw rate second-order differential value γ ″ (lateral acceleration of the axle position), and then in step S24. 9 searches / sets the second base value Drb2 from the yaw rate-damping force map of Fig. 9. Next, in step S25, the roll calculation control unit 56 compares the first base value Drb1 with the second base value Drb2. The larger absolute value is set as the roll damping force base value Drbase.

  When the roll damping force base value Drbase is set in step S25, the roll calculation control unit 56 determines in step S26 whether or not the current turning direction is left based on the lateral acceleration Gy. If the determination in step S26 is Yes, the roll calculation control unit 56 sets the roll damping force base value Drbase as it is to the roll target damping force Drtfl for the turning inner front wheel (left front wheel 3fl) in step S27, and step S28. Then, a value obtained by multiplying the roll damping force base value Drbase by a predetermined reduction coefficient Ki (for example, 0.1 to 0.2) is set as the roll target damping force Drtfr to Drtrr for the other wheels 3fr to 3rr, and then the step. In S29, each roll target damping force Drtfl to Drtrr is output.

  If the determination in step S26 is No, the roll calculation control unit 56 uses the roll damping force base value Drbase as it is as the roll target damping force Drtfr for the turning inner front wheel (right front wheel 3fr) in step S30, and step S31. Then, a value obtained by multiplying the roll damping force base value Drbase by the reduction coefficient Ki (for example, 0.1 to 0.2) is set as the roll target damping force Drtfl, Drtrl, Drtrr for the other wheels 3fl, 3rl, 3rr side. In step S29, each roll target damping force Drtfl to Drtrr is output.

  In the present embodiment, the roll target damping force other than the damper 6fl on the left front wheel 3fl side (or the damper 6fr on the right front wheel 3fr side) is reduced during cornering, so that it is easy to push up from the road surface. A good ride was secured. Further, taking the case of left turn as an example, as shown in FIG. 10, the difference between the loads Lfr, Lrr of the turning outer wheels 3fr, 3rr and the loads Lfl, Lrr of the turning inner wheels 3fl, 3rl at the time of transition is small. Therefore, as can be seen from the aforementioned load-cornering power diagram (FIG. 14), a larger average cornering power can be obtained, and the side slip of the tire 2 can be effectively suppressed.

[Second Embodiment]
FIG. 11 is a block diagram illustrating a schematic configuration of a roll calculation control unit according to the second embodiment. In the second embodiment, the configuration of the automobile and the damping force control device, the damping force control procedure, and the like are the same as those in the first embodiment, and therefore, a duplicate description is omitted.

  As shown in FIG. 11, the roll calculation control unit 56 of the second embodiment also has substantially the same configuration as that of the first embodiment described above, but based on the wheel speed vh from the wheel speed sensor 15 of each wheel 3. A slip determination unit 66 that determines the slip of the tire 2, and the roll target damping force setting unit 65 sets the roll target damping force using the determination result of the slip determination unit 66.

<Roll target damping force setting process>
In parallel with the above-described damping force control (FIG. 5), the roll calculation control unit 56 repeatedly executes a roll target damping force setting process whose procedure is shown in the flowchart of FIG. 12 at a predetermined processing interval. When the roll target value setting process is started, the roll calculation control unit 56 calculates a differential value (hereinafter referred to as a lateral acceleration differential value) Gy ′ of the lateral acceleration Gy input from the lateral G sensor 10 in step S41 of FIG. In step S42, the first base value Drb1 is retrieved / set using the lateral acceleration-damping force map of FIG.

  Next, in step S43, the roll calculation control unit 56 performs second-order differentiation on the yaw rate γ input from the yaw rate sensor 12 to calculate the yaw rate second-order differential value γ ″ (lateral acceleration of the axle position), and then in step S44. 9 searches / sets the second base value Drb2 from the yaw rate-damping force map of Fig. 9. Next, in step S45, the roll calculation control unit 56 determines the first roll damping force base value Dbr1 and the second base value Drb2. And the larger absolute value is set as the roll damping force base value Drbase.

  When the roll damping force base value Drbase is set in step S45, the roll calculation control unit 56 calculates the wheel accelerations vhfl 'to vhrr' by differentiating the wheel speeds vhfl to vhrr of each wheel 3 in step S46. Next, in step S47, the roll calculation control unit 56 determines whether any of these wheel accelerations vhfl 'to vhrr' exceeds a predetermined slip determination threshold value vh'th (for example, 2.0 G). If the determination in step S47 is No, the roll calculation control unit 56 sets the roll damping force base value Drbase as it is in step S48 to the roll target damping forces Drtfl to Drtrr for the damper 6 of each wheel 3, and in step S49, Roll target damping forces Drtfl to Drtrr are output.

  On the other hand, if the tire 2 of any of the wheels 3 slips and the determination in step S47 becomes Yes, the roll calculation control unit 56 determines whether the current traveling state is left-turning traveling in step S50 based on the lateral acceleration Gy. Determine whether or not. If the determination in step S50 is Yes, the roll calculation control unit 56 uses the roll damping force base value Drbase as it is as the roll target damping force Drtfl for the turning inner front wheel (left front wheel 3fl) in step S51, and step S52. Thus, the roll target damping forces Drtfr to Drtrr for the other wheels 3fr to 3rr are set to zero. Thereafter, the roll calculation control unit 56 outputs each roll target damping force Drtfl to Drtrr in step S49.

  On the other hand, if the determination in step S50 is No, the roll calculation control unit 56 uses the roll damping force base value Drbase as it is as the roll target damping force Drtfr for the turning inner front wheel (right front wheel 3fr) in step S53. In S54, roll target damping forces Drtfl, Drtrl, Drtrr for the other wheels 3fl, 3rl, 3rr are set to zero. Thereafter, the roll calculation control unit 56 outputs each roll target damping force Drtfl to Drtrr in step S49.

  The operations and effects of the second embodiment are also substantially the same as those of the first embodiment described above, but the roll target damping force other than the turning inner front wheel side is set to 0 only when the tire 2 slips. Can be further improved.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in damping force control during turning (steps S6 and S7), the one having the smallest absolute value among the three target damping forces may be selected (low selected) as the target damping force other than the turning front wheels. In this case, substantially the same effect as that of the first embodiment can be obtained. In addition, as long as it does not deviate from the gist of the present invention, the specific configuration of the automobile and the control device, the specific procedure of control, and the like can be appropriately changed.

1 is a schematic configuration diagram of a four-wheeled vehicle according to a first embodiment. It is a longitudinal section of the damper concerning a 1st embodiment. It is a block diagram which shows schematic structure of the damping-force control apparatus which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of the roll calculation control part which concerns on 1st Embodiment. It is a flowchart which shows the procedure of damping force control which concerns on 1st Embodiment. 3 is a target current map according to the first embodiment. It is a flowchart which shows the procedure of the roll target damping force setting process which concerns on 1st Embodiment. 3 is a lateral acceleration-damping force map according to the first embodiment. It is a yaw rate-damping force map concerning a 1st embodiment. It is a schematic diagram which shows the wheel load at the time of turning driving | running | working which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of the roll calculation control part which concerns on 2nd Embodiment. It is a flowchart which shows the procedure of the roll target damping force setting process which concerns on 2nd Embodiment. It is a schematic diagram which shows the wheel load at the time of turning traveling which concerns on the conventional apparatus. It is a load-cornering power diagram.

Explanation of symbols

1 Body 2 Tire 3 Wheel 6 Damper 8 ECU
10 Lateral G sensor (turning state quantity detection means)
12 Yaw rate sensor (turning state quantity detection means)
DESCRIPTION OF SYMBOLS 15 Wheel speed sensor 50 Damping force control apparatus 56 Roll calculation control part 61 1st base value setting part 62 2nd base value setting part 63 Roll base value setting part 64 Turning direction determination part 65 Roll target damping force setting part (roll target damping | damping part) Force setting means)
66 Slip judgment part (wheel slip state detection means)
V car

Claims (3)

A control device mounted on a vehicle in which a damping force variable damper is interposed between a vehicle body and each wheel, and used for damping force control of the damping force variable damper,
A turning state amount detecting means for detecting a turning state amount of the vehicle;
Roll target damping force setting means for individually setting the roll target damping force of each damping force variable damper based on the detection result of the turning state quantity detecting means,
The roll target damping force setting means reduces the roll target damping force on the other side than the front inner wheel side when the vehicle is in a turning running state. Wheel slip state detecting means for detecting the slip state of each wheel is further provided,
The roll target damping force setting means reduces the roll target damping force other than that on the turning inner front wheel side only when it is detected by the wheel slip state detection means that any of the wheels is slipping. The damping force variable damper control device according to claim 1. A control method of a damping force variable damper provided for suspension of a vehicle,
Processing for detecting a turning state amount of the vehicle;
A process of setting a roll target damping force of the damping force variable damper based on the turning state quantity ;
A process for determining whether or not the vehicle is turning.
A control method for a variable damping force damper, comprising: a process of reducing a roll target damping force on a side other than the inside front wheel side when the vehicle is determined to be turning.

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