JP2008230285A - Control device of damper with variable damping force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a damper with variable damping force equipped with an enhanced riding comfort by improving the control responsiveness etc. <P>SOLUTION: An energy change calculation control part 55 calculates the kinetic energy changing velocity u1' by subjecting the kinetic energy u1 to time differentiation, at step S13, and calculates the spring energy changing velocity u2' by subjecting the spring energy u2 to time differentiation, at step S16. Then the energy change calculation control part 55 calculates the energy multiplied value U using the formula U=u1'*(-u2'), at step S17, determines the energy change control target value Dea by multiplying the energy multiplied value U by a prescribed factor k, at step S18, and emits the energy change control target value Dea, at step S20, after removing the noise component from obtained Dea, at step S19. <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 ride comfort by improving control response and the like.

  In recent years, various types of cylindrical dampers that make up suspensions for automobiles have been developed, with variable damping force that variably controls the damping force according to the state of motion of the automobile, in order to achieve both high handling stability and ride comfort. Has been. As the damping force variable damper, a mechanical type in which a rotary valve that changes the orifice area is provided on the piston and this rotary valve is driven to rotate by an actuator has been the mainstream, but simplification of the configuration and improvement of responsiveness etc. To achieve this, a magnetorheological fluid (Magnet-Rheological Fluid: hereinafter referred to as MRF) is used as the hydraulic oil, and the viscosity of the MRF is controlled by a magnetic fluid valve (Magnetizable Liquid Valve: hereinafter referred to as MLV) provided on the piston. (Hereinafter referred to as an MRF damping force damper) and the like have appeared (see Patent Document 1).

When controlling the damping force damper, the damping force control device determines the target damping force for each wheel based on the vertical acceleration, lateral acceleration, longitudinal acceleration, etc. of the vehicle body. The drive current supplied to the MLV is set. For example, when suppressing the vertical movement of the vehicle body when traveling on a rough road, the damping force control device calculates the vertical speed (sprung speed) of the vehicle body by integrating the sprung acceleration, and the sprung speed decreases. Thus, the drive current is set (see Patent Document 2).
JP 2006-273223 A JP 2006-69527 A

  In the method of Patent Document 2 described above, since damping force control is performed according to the sprung speed, the damping force does not increase or decrease until the vehicle body actually moves up and down, and it is inevitable that a slight response delay occurs. It was. On the other hand, it is conceivable to perform damping force control based on the vertical speed (unsprung speed) of the wheel, but in this case, the vertical movement of the vehicle body corresponding to the vertical movement of the wheel cannot be accurately determined. It is difficult to perform control according to the vertical movement of the vehicle body.

  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 improvement in riding comfort by improving control responsiveness and the like.

  In order to solve the above problem, a damping force variable damper control device according to the invention of claim 1 is provided in a vehicle in which a suspension including a suspension spring and a damping force variable damper is interposed between a wheel and a vehicle body, Kinetic energy change speed detecting means for detecting a change speed of kinetic energy of the vehicle body as a kinetic energy change speed; Spring energy change speed detecting means for detecting a change speed of elastic energy of the suspension spring as a spring energy change speed; And a damping force setting means for setting a target damping force of the damping force variable damper based on the kinetic energy change rate and the spring energy change rate.

  According to a second aspect of the present invention, in the damping force variable damper control device according to the first aspect, the damping force setting means is different in the direction of the kinetic energy change speed and the direction of the spring energy change speed. In this case, the target damping force is increased, and the target damping force is reduced when the direction of the kinetic energy change speed and the direction of the spring energy change speed coincide with each other.

  According to a third aspect of the present invention, in the damping force variable damper control device according to the first aspect, the damping force setting means calculates the sum of the kinetic energy change speed and the spring energy change speed as a total energy change. In the case of speed, the target damping force is increased when the total energy change rate is small, and the target damping force is decreased when the total energy change rate is large.

  According to the present invention, since the target damping force is set based on the kinetic energy and the change rate of the spring energy, the responsiveness and accuracy of the damping force control can be improved compared to the case where the sprung speed or the unsprung speed is used. It will be possible to improve riding comfort.

  Hereinafter, an embodiment 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 showing a main configuration of the energy change calculation control 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, a vehicle body 1 of an automobile (vehicle) V has wheels 3 with tires 2 mounted on the front, rear, left and right thereof. Each wheel 3 is a suspension arm 4 and a spring (suspension spring) 5. The suspension 1 is suspended on the vehicle body 1 by a suspension 7 including a damping force variable damper (hereinafter simply referred to as a damper) 6 or the like. The vehicle V includes an ECU (Electronic Control Unit) 8 used for various controls, a vehicle speed sensor 9 that detects 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 or the like for detecting the yaw rate is installed at an appropriate position of the vehicle body 1. Further, in the automobile V, a vertical G sensor (state quantity detection means) 13 for detecting vertical acceleration in the vicinity of the wheel house and a stroke sensor 14 for detecting the stroke amount of the damper 6 are installed for each of the wheels 3fl to 3frr. ing.

  The ECU 8 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and a damper for each wheel 3 via a communication line (CAN (Controller Area Network in this embodiment)). 6 and each sensor 9-14.

<Damper>
As shown in FIG. 2, the damper 6 of the present 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, and a lower portion of the cylinder 22 The main components are a free piston 28 defining a high-pressure gas chamber 27, a cover 29 for preventing dust from adhering to the piston rod 23 and the like, and a bump stop 30 for buffering at the time of full bound.

  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 through a pair of upper and lower bushes 32 and a nut 33 at the upper end stud 23a.

  The piston 26 is provided with an annular 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 annular 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 annular communication path 41, and the ferromagnetic fine particles form a chain cluster. As a result, the apparent viscosity of the MRF passing through the annular 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 14 are connected, the roll moment, the pitch moment, the sprung speed, and the like obtained from the detection signals of the sensors 9 to 13. A damping force setting unit 52 that sets a target damping force, a driving current generation unit 53 that generates a driving current to each damper 6 (MLV coil 42) according to the target damping force input from the damping force setting unit 52, and a drive The output interface 54 outputs the drive current generated by the current generator 53 to each damper 6. The damping force setting unit 52 includes an energy change calculation control unit 55 used for energy change 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.

<Energy change calculation control unit>
As shown in FIG. 4, the energy change calculation control unit 55 includes a kinetic energy calculation unit 61 that calculates the kinetic energy u1 of the vehicle body 1, and a kinetic energy change rate calculation unit that calculates the kinetic energy change rate u1 ′ (kinetic energy change). Speed detecting means) 62, a spring energy calculating section 63 for calculating the spring energy u2, a spring energy changing speed calculating section (spring energy changing speed detecting means) 64 for calculating the spring energy changing speed u2 ', and a spring energy changing speed. a sign conversion unit 65 that converts the sign of u2 ′, a multiplication unit 66 that calculates an energy multiplication value U from the kinetic energy change rate u1 ′ and the sign-converted spring energy change rate u2 ′, and an energy change from the energy multiplication value U Control target value calculating means 67 for calculating the control target value Dea; And a low pass filter 68 to remove noise components of the target value Dea comprises for each wheel 3.

<< Operation of Embodiment >>
<Damping force control>
When the automobile starts running, the damping force control device 50 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 the acceleration of the vehicle body 1 obtained from the lateral G sensor 10, the longitudinal G sensor 11, and the vertical G sensor 13 in step S1 in FIG. The motion state of the vehicle V (the sprung speed at each wheel, etc.) is determined based on the vehicle speed input from the steering angle sensor (not shown) and the like. Next, the damping force control device 50 calculates the energy change control target value Dea of each damper 6 in step S2 based on the motion state of the vehicle V, and calculates the roll control target value Dr of each damper 6 in step S3. In step S4, the pitch control target value Dp of each damper 6 is calculated.

  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 the case of operation), in step S6, the largest control value among the three control target values Dea, Dr, Dp is set as the target damping force Dtgt. 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 control target values Dea, Dr, and Dp in step S7. The smallest value is set as the target damping force.

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

<Calculation of energy change control target value>
In parallel with the damping force control described above, the energy change calculation control unit 55 in the damping force control device 50 calculates an energy change control target value whose procedure is shown in the flowchart of FIG. 7 with a predetermined processing interval. When the calculation of the energy change control target value is started, the energy change calculation control unit 55 obtains the vertical speed v of the vehicle body 1 by integrating the detection signal of the vertical G sensor 13 in step S11 of FIG. the S12 with vertical velocity v and the vehicle body weight m calculates a vehicle body 1 of the kinetic energy u1 (mv ^2/2), to calculate the kinetic energy change rate u1 'by further differentiating the kinetic energy u1 time in step S13 .

Next, the energy change calculation control unit 55 obtains the deflection amount X of the spring 5 from the stroke amount signal of the damper 6 input from the stroke sensor 14 in step S14, and then uses the spring constant K in step S15 to determine the spring energy u2. ^(KX 2/2), and calculates the spring energy change rate u2 'by further differentiating the step S16 Debane energy u2 time.

When the calculation of the kinetic energy change rate u1 ′ and the spring energy change rate u2 ′ is completed, the energy change calculation control unit 55 calculates the energy multiplication value U by the following equation (1) in step S17.
U = u1 ′ · (−u2 ′) (1)

  Next, the energy change calculation control unit 55 obtains the energy change control target value Dea by multiplying the energy multiplication value U by a predetermined coefficient k in step S18, and removes the noise component of the energy change control target value Dea in step S19. After that, the energy change control target value Dea is output in step S20.

  The reason for converting the sign of the spring energy change rate u2 'in the above-described equation (1) is as described below. As shown in FIG. 8, for example, when the vehicle body 1 moves up and down during traveling on a flat road, it is necessary to increase the damping force to absorb energy. At this time, the total energy of the automobile V is substantially constant (that is, the change speed of the total energy is approximately 0), but the kinetic energy U1 and the spring energy U2 change in opposite directions, so the energy is converted by changing the sign. The multiplication value U (that is, the energy change control target value Dea) needs to be a positive value. On the other hand, as shown in FIG. 9, for example, when the vehicle body 1 and the wheel 3 move up and down during traveling on an uneven road, the damping force is reduced (in this embodiment, 0) from the wheel 3 side to the vehicle body 1 side. It is necessary to make it difficult for vibration to be transmitted. At this time, the total energy of the automobile V greatly changes (that is, the rate of change of the total energy increases), and the kinetic energy U1 and the spring energy U2 increase or decrease in substantially the same manner. The value U (that is, the energy change control target value Dea) needs to be a negative value.

  In the present embodiment, by adopting such a configuration, the damping force of the damper 6 can be increased / decreased (that is, the control responsiveness is increased) before the vehicle body 1 actually moves up and down, and the ride comfort is improved. Significant improvement is realized.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in the above embodiment, the target damping force is set according to the direction of the kinetic energy change speed and the direction of the spring energy change speed, but the target damping force is set according to the total energy change speed. Also good. In addition, the specific configuration of the control device, the specific procedure of the control, 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 the principal part structure of the energy change calculation 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 flowchart which shows the calculation procedure of the energy change control target value which concerns on embodiment. It is a graph which shows the relationship between the kinetic energy and spring energy which concern on embodiment. It is a graph which shows the relationship between the kinetic energy and spring energy which concern on embodiment.

Explanation of symbols

1 Car body 3 Wheel 5 Spring (Suspension spring)
6 Damping force variable damper 7 Suspension 13 Vertical G sensor 14 Stroke sensor 50 Damping force control device 52 Damping force setting unit (damping force setting means)
55 Energy change calculation control unit 61 Kinetic energy calculation unit 62 Kinetic energy change rate calculation unit (kinetic energy change rate detection means)
63 Spring energy calculation unit 64 Spring energy change rate calculation unit (spring energy change rate detection means)
V car

Claims (3)

A suspension including a suspension spring and a damping force variable damper is provided in a vehicle interposed between a wheel and a vehicle body,
Kinetic energy change speed detecting means for detecting a change speed of kinetic energy of the vehicle body as a kinetic energy change speed;
A spring energy change rate detecting means for detecting a change rate of elastic energy of the suspension spring as a spring energy change rate;
A damping force variable damper control device comprising damping force setting means for setting a target damping force of the damping force variable damper based on the kinetic energy changing speed and the spring energy changing speed.   The damping force setting means increases the target damping force when the direction of the kinetic energy change rate is different from the direction of the spring energy change rate, and sets the direction of the kinetic energy change rate and the spring energy change rate. 2. The damping force variable damper control device according to claim 1, wherein the target damping force is reduced when the directions coincide with each other. 3.   The damping force setting means increases the target damping force when the total energy change rate is small when the sum of the kinetic energy change rate and the spring energy change rate is the total energy change rate, and the total energy change rate. 2. The damping force variable damper control device according to claim 1, wherein the target damping force is reduced when the value is large.

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