JP2008260321A - 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 capable of stably generating appropriate damping force even in a minimal stroke of the damper. <P>SOLUTION: When the absolute value of a stroke speed Ss of the damper is not larger than a predetermined determination threshold value Ssth, and the determination in a step S5 becomes No, the damper control device 50 sets a target damping force in a step S11, assumes that the direction of the target damping force and the direction of the stroke of the damper 4 are same in a step S12, searches a target current Itgt from a drive current map based on the target damping force and the stroke speed of the damper 4 in a step S8, and outputs the drive current to an MLV coil 40 of each damper 4 in a step S9. For example, when the direction of the target damping force is at an expansion side, the damping control device sets the target current Itgt, in the case of the expansion side of the direction of the stroke, but even when the direction of the stroke is at a contraction side, the control device sets the same target current Itgt as the case of the expansion side of the direction of the stroke. <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 stably generating an appropriate damping force even during a minute stroke of the damper.

  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. In order 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 MRF type damping force damper) has appeared (see Patent Document 1).

In controlling the MRF type damping force damper, the damper control device sets a target damping force for each wheel based on the lateral acceleration and longitudinal acceleration of the vehicle body, and the MLV is converted from the target damping force and the stroke speed of the damper. A target value (target current) of the drive current to be supplied is set. In general, when a vehicle travels, minute noise is mixed in the output of the lateral acceleration sensor or the longitudinal acceleration sensor, and it is inevitable that the set value of the target damping force becomes excessive or small due to this noise. When traveling straight at a constant speed, the absolute amount of lateral acceleration and longitudinal acceleration is small, so the effect of noise increases, and an appropriate target damping force (ie, target current) cannot be obtained, resulting in ride comfort and control. There is a risk that stability will be reduced. Therefore, Patent Document 1 proposes a method of reducing the increase or decrease of the damping force by setting the target current with respect to the target damping force to be small in the vicinity of the stroke speed of zero.
JP 2006-273223 A

  However, even if the method of Patent Document 1 is adopted, the MLV has a very short period between the expansion side and the contraction side during the high-speed traveling in which the wheels slightly vibrate up and down. There is a problem that a stable damping force cannot be obtained due to hunting of the drive current. This is because when the direction of the target damping force set by the damper control device and the stroke direction of the damper are different, the damping force cannot be generated in the direction opposite to the direction of the target damping force, and is supplied to the MLV. This is because the drive current becomes zero. That is, when the target current value set from the target damping force is relatively large, if the stroke direction changes between the expansion side and the contraction side, the target current is between that value and 0 as shown in FIG. As a result, hunting is performed and an appropriate damping force cannot be obtained. In addition, this hunting is not preferable from the viewpoint of durability of the damper control device because it imposes a large burden on a driver that outputs a drive current to the MLV.

  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 can stably generate an appropriate damping force even during a minute stroke of the damper. .

  The invention of claim 1 is a control device for controlling a damping force of a damping force variable damper provided for suspension of a vehicle body, and sets a target damping force on an expansion side or a contraction side based on a motion state of the vehicle body. A target damping force setting means; and a control amount setting means for setting a control amount of the damping force variable damper based on a setting result of the target damping force setting means and a stroke speed of the damping force variable damper. When the stroke speed is within a predetermined determination range including 0, the control amount setting means considers that the direction of the target damping force and the stroke direction of the damping force variable damper are the same.

  According to a second aspect of the present invention, there is provided the damping force variable damper control device according to the first aspect, wherein a plurality of the target damping force setting means exist, and the control amount setting means includes the stroke speed of zero. When the stroke speed is within a predetermined determination range, the target damping force selected when the stroke speed is on the expansion side among the target damping forces set by the plurality of target damping force setting means, and the stroke speed are The control amount is set based on a larger absolute value from a target damping force selected in the case of being on the contraction side.

  According to a third aspect of the present invention, there is provided the damping force variable damper control device according to the first aspect, wherein a plurality of the target damping force setting means are present, and the control amount setting means includes the stroke speed of zero. When the stroke speed is within a predetermined determination range, the target damping force selected when the stroke speed is on the expansion side among the target damping forces set by the plurality of target damping force setting means, and the stroke speed are The control amount is set on the basis of the smaller absolute value from the target damping force selected in the case of the contraction side.

  According to a fourth aspect of the present invention, there is provided the damping force variable damper control device according to the first aspect, wherein the target damping force setting means includes a plurality of target damping force setting means, and the control amount setting means includes the stroke speed of zero. An absolute value of a target damping force that is selected when the stroke speed is on the expansion side, and an absolute value of a target damping force that is selected when the stroke speed is on the contraction side when within the predetermined determination range; The control amount is set on the basis of the average value.

  Further, the invention of claim 5 is the damping force variable damper control device according to claim 1, wherein there are a plurality of the target damping force setting means, and the control amount setting means includes a stroke speed of zero. When shifting from the contraction side to a predetermined determination range, the control amount is set based on the absolute value of the target damping force selected when the stroke speed is on the expansion side, and the stroke speed includes a predetermined value including zero. Based on the absolute value of the target damping force selected when the stroke speed is on the contraction side, out of the target damping forces set by the plurality of target damping force setting means, respectively, when transitioning from the extension side to the determination range. Then, the control amount is set.

  According to a sixth aspect of the present invention, there is provided the damping force variable damper control device according to the first aspect, wherein a plurality of the target damping force setting means exist, and the control amount setting means includes the stroke speed of zero. The absolute value of the target damping force that is selected when the stroke speed is on the contraction side among the target damping forces set by the plurality of target damping force setting means when the predetermined determination range is shifted from the contraction side. The control amount is set based on the stroke, and when the stroke speed shifts from the expansion side to a predetermined determination range including 0, the stroke among the target damping forces respectively set by the plurality of target damping force setting means The control amount is set based on an absolute value of a target damping force selected when the speed is on the extension side.

  The invention of claim 7 is the damping force variable damper control device according to any one of claims 1 to 6, wherein the control amount setting means has a predetermined stroke speed of zero. When it is within the determination range, the control amount for the target damping force is set small.

  According to an eighth aspect of the present invention, in the damping force variable damper control device according to any one of the first to seventh aspects, the vibration frequency detecting means for detecting the vibration frequency of the variable damping force damper is provided. In addition, the control amount setting means narrows the determination range when the detection result of the vibration frequency detection means exceeds the resonance frequency of the vehicle body, and controls the control amount for the target damping force within the determination range. Is set to be small.

  According to a ninth aspect of the present invention, there is provided the damping force variable damper control device according to any one of the first to eighth aspects, wherein the vehicle body predicts at least one of a roll motion and a pitch motion of the vehicle body. A behavior change predicting means, wherein the control amount setting means widens the determination range and determines the determination when at least one of roll movement and pitch movement of the vehicle body is predicted by the vehicle body behavior change prediction means. A control amount for the target damping force within a range is increased.

  According to the first aspect of the present invention, the hunting of the control amount does not occur even when the wheel slightly vibrates up and down during high-speed traveling or the like and the damper stroke direction changes at a very short cycle, and appropriate damping is achieved. Force can be generated stably. According to the invention of claim 2, in a state where the damper makes a slight stroke, the value of the target damping force is set to be relatively high and the change in the posture of the vehicle is suppressed. According to the invention of claim 3, in a state where the damper makes a slight stroke, the value of the target damping force is set to be relatively low and the riding comfort is improved. According to the invention of claim 4, in the state where the damper makes a slight stroke, the value of the target damping force is leveled, and both the suppression of the change in the posture of the vehicle and the improvement of the riding comfort are compatible. According to the invention of claim 5, in a situation where the sign change of the stroke speed is expected, the sign of the target damping force can be changed quickly, and the control responsiveness caused by the rise delay of the drive current or the like can be achieved. Reduction is suppressed. According to the sixth aspect of the present invention, even if noise is mixed in a sensor that detects the motion state of the vehicle body, the influence of the noise on ride comfort and steering stability can be suppressed. According to the invention of claim 7, for example, when the stroke speed is near 0, the control amount for the target damping force is set to be relatively small, and the control amount for the noise included in the target damping force can be suppressed. Ride comfort is improved. According to the invention of claim 8, overshoot and undershoot of the damping force immediately after the change of the sign of the stroke speed is effectively suppressed. According to the invention of claim 9, the damping force of the damper increases before the vehicle body actually rolls or pitches, so that the behavior change of the vehicle body is effectively suppressed. Lateral acceleration and longitudinal acceleration can be quickly generated with respect to steering and acceleration / deceleration.

  Hereinafter, several embodiments in which the present invention is applied to a four-wheel passenger car will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a four-wheeled 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 an outline of a damper control device according to the first embodiment. It is a block diagram which shows a structure.

<< 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, in the vehicle V, a lateral G sensor 10 that detects lateral acceleration, a longitudinal G sensor 11 that detects longitudinal acceleration, and the like are arranged at appropriate positions of the vehicle body 1, and a stroke sensor 12 that detects the displacement of the damper 4; A vertical G sensor 13 for detecting vertical acceleration in the vicinity of the wheel house is provided for each wheel 3.

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

<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 so that the ferromagnetic fine particles form a chain cluster, and the appearance of the MRF that passes 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 10 to 13 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 10, 11, and 13. 52, a target damping force selection unit 53 that selects one of the three target damping forces input from the damping force setting unit 52 based on the detection result of the stroke sensor 12, and the target damping force selection unit 53. A drive current generation unit 54 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 12, and the drive current generated by the drive current generation unit 54 is converted to each damper 4 And an output interface 55 for outputting to the network. The damping force setting unit 52 includes a skyhook control unit (target damping force setting unit) 56 used for skyhook control, a roll control unit (target damping force setting unit) 57 used for roll control, and a pitch. A pitch controller (target damping force setting means) 58 and the like used for control are accommodated.

<< Operation of First Embodiment >>
When the automobile starts running, the damper control device 50 executes damping force control whose procedure is shown in the flowchart of FIG. 4 at a predetermined processing interval (for example, 10 ms). When the damping force control is started, the damper 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 of FIG. 1), the motion state of the automobile V is determined based on the vehicle speed input from the steering angle sensor (not shown), the steering speed input from the steering angle sensor, 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 absolute value of the stroke speed Ss of each damper 4 exceeds a predetermined determination threshold Ssth in step S5 (whether the stroke speed Ss is not within the determination range including 0). ) Respectively. If the determination in step S5 is Yes, the damper control device 50 determines whether or not the stroke speed Ss is a positive value in step S6, and if this determination is Yes (ie, the damper). 4 is operating on the extension side), the largest control value (maximum value) among the three control target values Dsh, Dr, Dp is set as the target damping force Dtgt in step S7. At this time, when the maximum value is a negative value, the damper control device 50 sets the target damping force Dtgt to 0. Thereafter, the damper control device 50 retrieves the target current Itgt from the drive current map of FIG. 5 in step S8, and then outputs the drive current to the MLV coil 40 of each damper 4 in step S9.

  Further, when the determination in step S6 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 S10. Is set to the target damping force Dtgt. At this time, when the minimum value is a positive value, the damper control device 50 sets the target damping force Dtgt to 0. Thereafter, the damper control device 50 retrieves the target current Itgt from the drive current map of FIG. 5 in step S8, and then outputs the drive current to the MLV coil 40 of each damper 4 in step S9.

  On the other hand, when the absolute value of the stroke speed Ss of each damper 4 is equal to or less than the predetermined determination threshold Ssth (that is, the stroke speed Ss is within the determination range including 0), and the determination in step S5 is No, the damper control is performed. In step S11, the apparatus 50 executes a target damping force setting process whose procedure is shown in the flowchart of FIG. When the damper control device 50 starts the target damping force setting process, after calculating the absolute values | Dsh |, | Dr |, | Dp | of the three control target values Dsh, Dr, Dp in step S21 of FIG. In step S22, as shown in FIG. 7, a control target value selected when the stroke speed is on the extension side (hereinafter referred to as an extension side target value: skyhook control target value Dsh in this embodiment), A control target value having a large absolute value from a control target value selected when the stroke speed is on the contraction side (hereinafter referred to as a contraction side target value: pitch control target value Dp in this embodiment) (in FIG. The skyhook control target value Dsh) is adopted as the target damping force Dtgt. Accordingly, the target damping force Dtgt is set to be relatively high in the vicinity of the stroke speed Ss being 0, and the change in the posture of the vehicle is suppressed.

  Next, the damper control device 50 considers that the direction of the target damping force Dtgt and the stroke direction of the damper 4 are the same in step S12 of FIG. 4, and drives based on the target damping force Dtgt and the stroke speed Ss in step S8. The target current Itgt is retrieved from the current map, and the drive current is output to the MLV coil 40 of each damper 4 in step S5. For example, when the direction of the target damping force is the extension side, as shown in the upper part of FIG. 8 (enlarged view of the VIII portion in FIG. 5), the stroke direction is of course the extension direction. Even on the contraction side, the same target current Itgt is set as when the stroke direction is the expansion side. Thereby, in this embodiment, when the target damping force is on the expansion side as shown in FIG. 9, the stroke direction is at a very short cycle between the expansion side and the contraction side as shown in FIG. Even if it changes, the desired target current Itgt is obtained, and the damper 4 stably generates an appropriate damping force. As shown in the lower part of FIG. 8, even when the direction of the target damping force is on the contraction side, the same processing as that on the expansion side is performed.

[Second Embodiment]
In the second embodiment, the structure of the damper and the configuration of the damper control device and the procedure of damping force control are the same as those of the first embodiment described above, but the procedure of the target damping force setting process is different. That is, in the second embodiment, when the determination in step S5 of FIG. 4 is No, the damper control device 50 executes the target damping force setting process in the procedure shown in the flowchart of FIG. 11 in step S11. When the damper control device 50 starts the target damping force setting process, after calculating the absolute values | Dsh |, | Dr |, | Dp | of the three control target values Dsh, Dr, Dp in step S31 of FIG. In step S32, as shown in FIG. 12, the absolute value is obtained from the expansion side target value (skyhook control target value Dsh in this embodiment) and the contraction side target value (pitch control target value Dp in this embodiment). Is used as the target damping force Dtgt (the pitch control target value Dp in FIG. 12). Thereby, in the present embodiment, the target damping force Dtgt is set to be relatively small in the vicinity of the stroke speed Ss being 0, and the riding comfort is improved.

[Third Embodiment]
The third embodiment also differs from the first embodiment described above in the procedure of the target damping force setting process. That is, in the third embodiment, when the determination in step S5 of FIG. 4 is No, the damper control device 50 executes the target damping force setting process in the procedure shown in the flowchart of FIG. 13 in step S11. When the damper control device 50 starts the target damping force setting process, after calculating the absolute values | Dsh |, | Dr |, | Dp | of the three control target values Dsh, Dr, Dp in step S41 of FIG. In step S42, as shown in FIG. 14, the absolute value of the extension side target value (skyhook control target value Dsh in this embodiment) and the absolute value of the contraction side target value (pitch control target value Dp in this embodiment) are absolute. A simple average value is used as the target damping force Dtgt. Thereby, in this embodiment, since the target damping force Dtgt is equal to each control target value Dsh, Dr, Dp when the stroke speed Ss is near 0, the change in the posture of the vehicle and the improvement of the riding comfort are achieved. Will be compatible. In this embodiment, the simple average value of the absolute value of the expansion side target value and the absolute value of the contraction side target value is used as the target damping force Dtgt in step S42, but the absolute value and the contraction of the expansion side target value are used. A predetermined weighting coefficient may be set for each absolute value of the side target value, and the weighted average value may be adopted as the target damping force Dtgt.

[Fourth Embodiment]
The fourth embodiment also differs from the first embodiment described above in the procedure of the target damping force setting process. That is, in 4th Embodiment, when determination of step S5 of FIG. 4 becomes No, the damper control apparatus 50 performs a target damping force setting process in the procedure shown to the flowchart of FIG. When starting the target damping force setting process, the damper control device 50 determines whether or not the stroke speed Ss has shifted from the contraction side to the determination range in step S51 of FIG. If the determination in step S51 is Yes, the damper control device 50 determines in step S52 whether the time change amount (differential value Ss ′) of the stroke speed Ss is greater than or equal to a predetermined determination threshold value Ss′th. If the determination in step S52 is also Yes, the damper control device 50 anticipates that the stroke speed Ss changes from negative to positive, and in step S53, as shown by the solid line arrow in FIG. A control target value (in this embodiment, the skyhook control target value Dsh) that has a large absolute value from the target value (skyhook control target value Dsh in the present embodiment) and the contraction side target value (pitch control target value Dp in the present embodiment). ) As the target damping force Dtgt. If the determination in step S52 is No, the damper control device 50 assumes that the stroke speed Ss is less likely to change from negative to positive, and in step S54, as indicated by the dashed arrow in FIG. A control target value (pitch control target value Dp in this embodiment) having a smaller absolute value from the expansion side target value and the contraction side target value is employed as the target damping force Dtgt.

  On the other hand, when the stroke speed Ss shifts from the extension side to the determination range and the determination in step S51 is No, the damper control device 50 determines that the time change amount (differential value Ss ′) of the stroke speed Ss is predetermined in step S55. It is determined whether it is more than the determination threshold value Ss'th. If the determination in step S55 is Yes, the damper control device 50 anticipates that the stroke speed Ss changes from positive to negative, and in step S54, as shown by the solid line arrow in FIG. Then, a control target value (pitch control target value Dp in this embodiment) whose absolute value is smaller than the contraction side target value is adopted as the target damping force Dtgt. Further, if the determination in step S55 is No, the damper control device 50 determines that the stroke speed Ss is less likely to change from positive to negative, and in step S53, as indicated by the dashed arrow in FIG. A control target value (skyhook control target value Dsh in this embodiment) having a larger absolute value from the expansion side target value and the contraction side target value is employed as the target damping force Dtgt.

  In the present embodiment, by performing such processing, a decrease in control responsiveness due to a drive current rising delay or the like is effectively suppressed, and steering stability, ride comfort, and the like are realized.

[Fifth Embodiment]
The fifth embodiment is also different from the first embodiment described above in the procedure of the target damping force setting process. That is, in the fifth embodiment, when the determination in step S5 of FIG. 4 is No, the damper control device 50 executes the target damping force setting process in the procedure shown in the flowchart of FIG. 18 in step S11. When starting the target damping force setting process, the damper control device 50 determines whether or not the stroke speed Ss has shifted from the contraction side to the determination range in step S61 in FIG. If the determination in step S61 is Yes, the damper control device 50 has a smaller absolute value from the expansion target value and the contraction target value, as indicated by the solid line arrow in FIG. 19 in step S62. A control target value (pitch control target value Dp in this embodiment) is adopted as the target damping force Dtgt. If the determination in step S61 is No, the damper control device 50 has a larger absolute value from the expansion side target value and the contraction side target value, as indicated by the dashed arrows in FIG. 19 in step S63. The control target value (skyhook control target value Dsh in this embodiment) is adopted as the target damping force Dtgt. Thereby, in this embodiment, even when noise is mixed in the detection signal of the stroke sensor 12 when the stroke speed Ss is in the vicinity of 0, the target damping force Dtgt changes suddenly (that is, changes like hunting). Will be eliminated and the ride quality will be improved.

[Sixth Embodiment]
In the sixth embodiment, the structure of the damper and the configuration of the damper control device and the damping force control procedure are the same as those in the first to fifth embodiments described above, but only the drive current map is different. That is, as shown in FIG. 20, in the driving current map of the sixth embodiment, the target current Itgt with respect to the target damping force is significant in a region where the absolute value of the stroke speed Ss of each damper 4 is within the predetermined determination threshold Ssth. (Same as the value of the target current with respect to the target damping force at the determination threshold value Ssth or -Ssth). As a result, even if the target damping force increases or decreases in a short cycle due to noise mixed in the detection signals of the lateral G sensor 10 and the front and rear G sensor 11, the change in the target current Itgt is reduced, and the vehicle travels at a constant speed. A decrease in ride comfort and handling stability at times is effectively suppressed. In the present embodiment, in a region where the absolute value of the stroke speed is within the predetermined determination threshold Ssth, the target current Itgt is set to the target at the determination threshold Ssth or −Ssth in order to reduce the target current Itgt with respect to the target damping force. Although it is set to be the same as the value of the target current with respect to the damping force, it is not necessarily set to be the same, and may be associated with a lower value.

[Seventh Embodiment]
The seventh embodiment is the same as the first to sixth embodiments described above with respect to the damper structure and the damper control device and the damping force control procedure, but it depends on the operating state of the damper and the behavior of the automobile. The difference is that the judgment range and the target current are changed. This embodiment prevents damping force overshoot and undershoot when the damper 4 resonates at a vibration frequency equal to or higher than the sprung resonance frequency and attenuates in advance when occurrence of roll motion or pitch motion is predicted. The purpose is to suppress the change in vehicle behavior by increasing the force.

  In the seventh embodiment, in parallel with the above-described damping force control, resonance / behavior change corresponding control whose procedure is shown in the flowchart of FIG. 21 is executed. When the resonance / behavior change control is started, the damper control device 50 determines whether or not the damper 4 vibrates with a vibration frequency equal to or higher than the sprung resonance frequency (for example, 1.3 Hz) in step S71 of FIG. It is determined whether or not the automobile V is traveling on a road surface with small unevenness.

  In the case of the present embodiment, the vibration frequency of the damper 4 is, as shown in FIG. 22, when the stroke speed Ss of the damper 4 exceeds either one of positive and negative threshold values (shown by a broken line in FIG. 22). Is calculated as the reciprocal of a value obtained by doubling this elapsed time t1. When the stroke speed Ss of the damper 4 does not exceed the threshold value even after the half period t2 of the sprung resonance frequency has elapsed since the stroke speed Ss finally exceeded the threshold value, the damper control device 50 It is determined that the vibration at the upper resonance frequency or more has subsided (the small unevenness on the road surface has been eliminated). This determination is based on the reversal cycle of the stroke speed Ss, the vertical acceleration of the vehicle body 1 and its reversal cycle, the vertical acceleration of the wheel 3 and its reversal cycle, the reversal cycle of the longitudinal acceleration of the vehicle body 1, and the reversal cycle of the lateral acceleration of the vehicle body 1. Or the like.

  If the determination in step S71 is Yes, the damper control device 50 causes the determination threshold value Ssth to approach 0 (that is, the determination range is reduced) in step S72. Next, the damper control device 50 determines whether or not the absolute value of the stroke speed Ss of each damper 4 exceeds the determination threshold Ssth in step S73 (whether the stroke speed Ss is not within the determination range including 0). Each determination is made, and if this determination is No, the target current Itgt is decreased by multiplying by a predetermined reduction coefficient K1 in step S74.

  FIG. 23 is a graph showing changes in the stroke speed Ss and changes in the actual damping force Dreal during sprung resonance. As can be seen from the figure, the actual damping force Dreal (indicated by a broken line in FIG. 23) in the first to sixth embodiments changes the sign of the actual stroke speed Ss in the determination range in which the stroke speed Ss is regarded as zero. Even if it is determined that there is no change and the target current Itgt in the determination range is large, a large overshoot or undershoot occurs immediately after the sign of the stroke speed Ss changes. This is because, for example, when the stroke speed Ss shifts to the determination range regarded as 0 from the contraction side, a large target current Itgt is generated from the time when it enters the determination range, so that it is excessive compared to the case where normal control is performed. This is because a strong damping force is generated. However, in the actual damping force Dreal (shown by a solid line in FIG. 23) in the present embodiment, the determination range is narrowed and the target current Itgt within the determination range is reduced, so that the above-described overshoot and undershoot are reduced. The shoot was very small.

On the other hand, if the determination in step S71 is No, the damper control device 50 determines whether or not roll motion or pitch motion is predicted to occur in the vehicle body 1 in step S75. In the present embodiment, the absolute value of the differential value of the lateral acceleration exceeds a predetermined threshold (for example, 2 m / S ³ ), or the absolute value of the differential value of the longitudinal acceleration is a predetermined threshold (for example, 2 m / S ³ ). It is predicted that roll motion or pitch motion will occur in the vehicle body 1 when the value exceeds. This determination may be made based on the differential value of the lateral acceleration equivalent amount obtained from the yaw rate and the vehicle speed, or the differential value of the lateral acceleration equivalent amount obtained from the steering angle and the vehicle speed.

  If the determination in step S75 is Yes, the damper control device 50 increases the determination threshold Ssth in step S76 (that is, expands the determination range). Next, the damper control device 50 determines whether or not the absolute value of the stroke speed Ss of each damper 4 exceeds the determination threshold Ssth in step S77 (whether the stroke speed Ss is not within the determination range including 0). Each determination is made, and if this determination is No, the target current Itgt is increased by multiplying by a predetermined expansion coefficient K2 in step S78. As a result, the damping force of the damper 4 is increased before the vehicle body 1 actually rolls or pitches, and the behavior change of the vehicle body 1 is effectively suppressed, and steering, acceleration / deceleration are performed. As a result, lateral acceleration and longitudinal acceleration can be promptly generated.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in the above embodiment, the present invention is applied to the MRF type damping force damper and the driving current is used as the control amount. For example, the present invention is applied to a mechanical damping force variable damper and the rotary valve is operated as the control amount. An amount or the like may be used. Further, in the above embodiment, when the absolute value of the stroke speed is equal to or less than the predetermined determination threshold value, the direction of the target damping force and the stroke direction of the damping force variable damper are considered to be the same. The determination threshold may be set individually for the contraction side. In addition, the specific configuration of the automobile, the specific control procedure, and the like can be changed as appropriate without departing from the scope of the present invention.

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 damper control apparatus which concerns on 1st Embodiment. It is a flowchart which shows the procedure of damping force control which concerns on 1st Embodiment. It is a drive current map concerning a 1st embodiment. It is a flowchart which shows the procedure of the target damping force setting process which concerns on 1st Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 1st Embodiment. It is an VIII section enlarged view in FIG. It is a graph which shows the effect | action of 1st Embodiment. It is a graph which shows the effect | action of 1st Embodiment. It is a flowchart which shows the procedure of the target damping force setting process which concerns on 2nd Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 2nd Embodiment. It is a flowchart which shows the procedure of the target damping force setting process which concerns on 3rd Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 3rd Embodiment. It is a flowchart which shows the procedure of the target damping force setting process which concerns on 4th Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 4th Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 4th Embodiment. It is a flowchart which shows the procedure of the target damping force setting process which concerns on 5th Embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on 5th Embodiment. It is a drive current map concerning a 6th embodiment. It is a flowchart which shows the procedure of the resonance / behavior change corresponding | compatible control which concerns on 7th Embodiment. It is a graph which shows the change of the stroke speed at the time of driving concerning a 7th embodiment. It is a graph which shows the change of the stroke speed at the time of a sprung resonance, and the change of an actual damping force. It is a graph which shows the problem of a prior art.

Explanation of symbols

4 Damper 50 Damper Control Device 52 Damping Force Setting Unit 53 Target Damping Force Selection Unit 54 Drive Current Generation Unit 56 Skyhook Control Unit (Target Damping Force Setting Unit)
57 Roll control unit (target damping force setting means)
58 Pitch control unit (Target damping force setting means)
V car

Claims (9)

A control device for controlling the damping force of a damping force variable damper provided for suspension of a vehicle body,
A target damping force setting means for setting a target damping force on the extension side or the contraction side based on the motion state of the vehicle body;
Control amount setting means for setting the control amount of the damping force variable damper based on the setting result of the target damping force setting means and the stroke speed of the damping force variable damper;
The control amount setting means determines that the direction of the target damping force and the stroke direction of the damping force variable damper are the same when the stroke speed is within a predetermined determination range including zero. Control device for variable damper. There are a plurality of target damping force setting means,
When the stroke speed is within a predetermined determination range including 0, the control amount setting means has the stroke speed on the expansion side among the target damping forces set by the plurality of target damping force setting means. The control amount is set based on a larger absolute value from a target damping force selected in a case and a target damping force selected when the stroke speed is on the contraction side. Item 4. A damping force variable damper control device according to item 1. There are a plurality of target damping force setting means,
When the stroke speed is within a predetermined determination range including 0, the control amount setting means has the stroke speed on the expansion side among the target damping forces set by the plurality of target damping force setting means. The control amount is set based on a smaller absolute value from a target damping force selected in a case and a target damping force selected when the stroke speed is on the contraction side. Item 4. A damping force variable damper control device according to item 1. There are a plurality of target damping force setting means,
The control amount setting means is configured such that when the stroke speed is within a predetermined determination range including 0, the absolute value of the target damping force selected when the stroke speed is on the expansion side, and the stroke speed is on the contraction side. 2. The control device for a damping force variable damper according to claim 1, wherein the control amount is set based on an average value of an absolute value of a target damping force selected when the damping force is in the range. There are a plurality of target damping force setting means,
The control amount setting means includes
When the stroke speed shifts from the contraction side to a predetermined determination range including 0, the control amount is set based on the absolute value of the target damping force selected when the stroke speed is on the expansion side,
When the stroke speed shifts from the expansion side to a predetermined determination range including 0, it is selected when the stroke speed is on the contraction side among the target damping forces respectively set by the plurality of target damping force setting means. 2. The damping force variable damper control device according to claim 1, wherein the control amount is set based on an absolute value of a target damping force. There are a plurality of target damping force setting means,
The control amount setting means includes
When the stroke speed is shifted from the contraction side to a predetermined determination range including 0, it is selected when the stroke speed is on the contraction side among the target damping forces respectively set by the plurality of target damping force setting means. Set the control amount based on the absolute value of the target damping force
When the stroke speed shifts from the expansion side to a predetermined determination range including 0, it is selected when the stroke speed is on the expansion side among the target damping forces respectively set by the plurality of target damping force setting means. 2. The damping force variable damper control device according to claim 1, wherein the control amount is set based on an absolute value of a target damping force.   The control amount setting means sets the control amount for the target damping force to be small when the stroke speed is within a predetermined determination range including zero. A control device for a damping force variable damper described in one item. A vibration frequency detecting means for detecting a vibration frequency of the damping force variable damper;
When the detection result of the vibration frequency detection means exceeds the resonance frequency of the vehicle body, the control amount setting means narrows the determination range and sets a control amount for the target damping force within the determination range to be small. The damping force variable damper control device according to any one of claims 1 to 7, wherein the damping force variable damper control device is provided. Vehicle body behavior change prediction means for predicting at least one of roll motion and pitch motion of the vehicle body,
The control amount setting means widens the determination range and the target damping force within the determination range when at least one of roll movement and pitch movement of the vehicle body is predicted by the vehicle body behavior change prediction means. The control device for a damping force variable damper according to any one of claims 1 to 8, wherein a control amount for the control signal is increased.

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