JP2011116179A - 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 during a minute stroke of the damper. <P>SOLUTION: In the case that a step S54 is determined to be Yes, a damping force control part 50 searches a target current Itgt from a second target current map in a step S56. In other words, in the case of travelling on a smooth road while conducting a roll control and a pitch control, if an absolute value of a stroke speed Ss is smaller than a first determination threshold value Ssth1, the target current Itgt is determined by a target damping force Dtgt only. Even if a direction of the stroke speed Ss and a direction of the target damping force Dtgt is different, in the case that the absolute value of the stroke speed Ss is smaller than a second determination threshold value Ssth2, the target current Itgt is set regardless of the direction of the stroke speed Ss. <P>COPYRIGHT: (C)2011,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 damping force variable damper) has appeared (see Patent Document 1).

  In controlling the MRF type damping force variable damper, the damping force control unit sets a target damping force for each wheel based on the lateral acceleration and longitudinal acceleration of the vehicle body, and MLV is calculated from the target damping force and the stroke speed of the damper. The target value (target current) of the drive current supplied to the 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, in Patent Document 1, when the stroke speed is in a predetermined determination range including 0, the direction of the target damping force and the stroke direction of the damping force variable damper are considered to be the same, and the target current with respect to the target damping force is set to the stroke. A control method (see FIG. 20 of Patent Document 1) for setting without depending on the speed is disclosed. The determination range is set according to the sprung resonance state and the roll / pitch state (see FIG. 21 of Patent Document 1).

JP 2008-260321 A

  In the control method of Patent Document 1, if the stroke speed is within the determination range, the target current is uniformly set according to the target damping force. Therefore, the target damping force is short due to noise mixed in the detection signal of the sensor. Even when the period changes, the change in the target current is suppressed, and the riding comfort during straight traveling and the steering stability during cornering are improved. However, in the control method described above, since the determination range is set regardless of the state of the traveling road surface, it may be difficult to perform appropriate damping force control. In other words, when the determination range is set narrow when traveling on a rough road or the like, there is a possibility that the thrust due to the unevenness of the road surface acts on the vehicle body and the ride comfort is remarkably reduced. Further, in the above-described control method, when the stroke speed is within the determination range, the stroke speed and the target damping force are always considered to be the same, so that the skyhook control may not be performed smoothly when traveling straight on a flat road. It was. Furthermore, some recent automobiles include a mode switch for the driver to switch the damping mode of the damping force variable damper. However, it has been desired to change the determination range in accordance with each damping mode.

  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 according to claim 1 is a control device for controlling the damping force of the damping force variable damper provided for suspension of the vehicle body, the stroke speed obtaining means for obtaining the stroke speed of the damping force variable damper, Acceleration detecting means for detecting at least one of acceleration and longitudinal acceleration, target damping force setting means for setting a target damping force based on a motion state or a road surface state of the vehicle body, and a control amount of the damping force variable damper Control amount setting means for setting, the control amount setting means, a determination range setting means for setting a first determination range including 0 for the stroke speed based on the motion state or road surface state of the vehicle body, A road surface condition judging means for judging whether the road surface is a good road or a bad road based on the change in the stroke speed, and the vehicle body based on the lateral acceleration or the longitudinal acceleration of the vehicle body Posture change determining means for determining whether or not the posture change is abrupt, and when the stroke speed is out of the first determination range, the control is performed based on the target damping force and the stroke speed. On the other hand, when the stroke speed is within the first determination range, the control amount is set based only on the target damping force, and the determination range setting means is configured so that the traveling road surface is a good road. When it is determined that there is a sudden change in the posture, the first determination range is set to a predetermined reduction determination range, and when it is determined that the traveling road surface is a bad road, When the determination range is set to a predetermined expansion determination range, the road surface is determined to be a good road, and it is determined that the posture change is not abrupt, the first determination range is set as the reduction determination range and the expansion determination. Set between range And wherein the Rukoto.

  According to a second aspect of the present invention, in the damping force variable damper control device according to the first aspect of the present invention, the determination range setting means is configured to reduce the stroke speed to 0 when the posture change is determined to be abrupt. When the stroke speed is within the second determination range, the control amount setting means is configured such that the direction of the target damping force and the stroke direction of the damping force variable damper are the same. By considering this, the same control amount is set for the expansion side and the contraction side of the damping force variable damper.

  The third aspect of the invention is the damping force variable damper control device according to the first or second aspect of the invention, further comprising damping mode switching means that is switched by a driver, wherein the control amount setting means is the damping amount switching means. According to the switching state of the mode switching means, at least one of the first determination range and the second determination range is enlarged or reduced.

  According to the first aspect of the present invention, since the first determination range is appropriately set according to the state of the traveling road surface and the change in the posture of the vehicle, it is possible to achieve both high riding comfort and high handling stability. According to the invention of claim 2, for example, the ride comfort can be improved by narrowing the second determination range during the skyhook control. Further, according to the invention of claim 3, the first and second determination ranges are appropriately set according to the damping mode of the damping force variable damper, thereby realizing the ride comfort and driving stability intended by the driver. .

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 part which concerns on embodiment. It is a flowchart which shows the procedure of damping force control which concerns on embodiment. It is a drive current map concerning an embodiment. It is a flowchart which shows the procedure of the 1st determination threshold value setting process which concerns on embodiment. It is a graph which shows the judgment method of rough road driving concerning an embodiment. It is a flowchart which shows the procedure of the 2nd determination threshold value setting process which concerns on embodiment. It is a flowchart which shows the procedure of the target electric current setting process which concerns on embodiment. It is a graph which shows the relationship between the stroke speed and target damping force which concern on embodiment. It is a 1st target current map concerning an embodiment. It is a 2nd target current map concerning an embodiment. It is a 3rd target electric current map which concerns on embodiment. It is a 4th target current map concerning an embodiment. It is a graph which shows the effect | action of embodiment. It is a graph which shows the effect | action of embodiment. It is a graph which shows the problem of a prior art.

Hereinafter, an embodiment in which the present invention is applied to a four-wheel passenger vehicle will be described in detail with reference to the drawings.
1 is a schematic configuration diagram of a four-wheeled vehicle according to the 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 unit according to the embodiment. It is.

<< Configuration of Embodiment >>
<Schematic configuration of automobile>
First, a schematic configuration of an automobile according to an embodiment will be described with reference to FIG. In the description, for the four wheels and 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 variable damper (hereinafter simply referred to as a damper). It is suspended on the vehicle body 1 by a suspension 5 consisting of 4 etc. The automobile V is provided with a damper ECU (Electronic Control Unit) 7 and an EPS (Electric Power Steering) 8 which are control bodies of the damping force variable damper. 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. Further, a mode switch 14 for switching the damping mode of the damper 4 to three stages (normal position, sports position and comfort position) is installed in the driver's seat of the automobile V.

  The damper ECU 7 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and the damper 4 for each wheel via a communication line (CAN (Controller Area Network in this embodiment)). And each sensor 10-14 and the like.

<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. 2, the piston 26 is provided with an annular communication passage 39 that connects 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 a current is supplied from the damper ECU 7 to the MLV coil 40, a magnetic field is applied to the MRF flowing through the annular communication path 39 so that ferromagnetic fine particles form a chain cluster, and the MRF passing through the annular communication path 39 Apparent viscosity increases.

<Schematic configuration of damping force control unit>
The damper ECU 7 includes a damping force control unit 50 whose schematic configuration is shown in FIG. The damping force control unit 50 is a target of each damper 4 based on the input interface 51 to which the above-described sensors 10 to 13 and the mode switch 14 are connected, and input signals from the sensors 10, 11, 13 and the mode switch 14 and the like. A target damping force setting unit 52 for setting a damping force; a target damping force selecting unit 53 for selecting one of the three target damping forces input from the target damping force setting unit 52 based on the detection result of the stroke sensor 12; The drive current generator generates a drive current to each damper 4 (MLV coil 40) according to the target damping force selected by the target damping force selector 53 and the input signals from the sensors 10-13 and the mode switch 14. 54, and an output interface 55 that outputs the drive current generated by the drive current generation unit 54 to each damper 4. The target damping force setting unit 52 includes a skyhook control unit (skyhook control target value setting unit) 56 used for skyhook control, and a roll control unit (roll control target value setting unit used for roll control). Stage) 57, a pitch control unit (pitch control target value setting unit) 58 used for pitch control, and the like are accommodated.

<< Operation of Embodiment >>
When the vehicle starts running, the damping force control unit 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 damping force control unit 50 detects the acceleration of the vehicle body 1 and the vehicle speed sensor (not shown) 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 estimated on the basis of the vehicle body speed input from the control unit (not shown) and the steering speed input from the steering angle sensor (not shown). Next, the damping force control unit 50 calculates the skyhook control target value Dsh of each damper 4 in step S2 based on the estimated motion state of the vehicle V, and calculates the roll control target value Dr of each damper 4 in step S3. In step S4, the pitch control target value Dp of each damper 4 is calculated.

  Next, the damping force control unit 50 sets a first determination threshold value Ssth1 by performing a first threshold setting process described later in step S5, and performs a second threshold setting process described later in step S6. Set.

  Thereafter, the damping force control unit 50 determines whether or not the absolute value of the stroke speed Ss of each damper 4 exceeds both the first determination threshold value Ssth1 and the second determination threshold value Ssth2 in step S7 (the stroke speed Ss is 0). Whether or not they are within the first determination range and the second determination range. If the determination in step S7 is Yes, the damping force control unit 50 determines whether or not the stroke speed Ss is a positive value in step S8, and if this determination is Yes (ie, In the case where 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 S9. In this case, if the maximum value is a negative value, the damping force control unit 50 sets the target damping force Dtgt to 0. Thereafter, the damping force control unit 50 retrieves the target current Itgt from the drive current map of FIG. 5 in step S10, and then outputs the drive current to the MLV coil 40 of each damper 4 in step S11.

  In addition, when the determination in step S6 is No (that is, when the damper 4 is operating on the contraction side), the damping force control unit 50 determines that among the three control target values Dsh, Dr, and Dp in step S12. The smallest value (minimum value) is set as the target damping force Dtgt. In this case, if the minimum value is a positive value, the damping force control unit 50 sets the target damping force Dtgt to 0. Thereafter, the damping force control unit 50 retrieves the target current Itgt from the drive current map of FIG. 5 in step S10, and then outputs the drive current to the MLV coil 40 of each damper 4 in step S11.

  On the other hand, the absolute value of the stroke speed Ss of each damper 4 is equal to or less than the first determination threshold Ssth1 or the second determination threshold Ssth2 (that is, the stroke speed Ss is within the first determination range or the second determination range including 0). If the determination in step S7 is No, the damping force control unit 50 outputs a drive current to the MLV coil 40 of each damper 4 in step S11 after executing a target current setting process described later in step S13.

<First threshold setting process>
The damping force control unit 50 executes a first threshold setting process whose procedure is shown in the flowchart of FIG. 6 in step S5 of FIG. When the first threshold value setting process is started, the damping force control unit 50 first performs rough road determination in step S21 of FIG. The bad road determination is whether or not the vehicle V is traveling on a road surface with a rough surface (bad road) (that is, whether or not the damper 4 vibrates with an unsprung resonance frequency (for example, 15 Hz) or higher). ).

  In the case of the present embodiment, the vibration frequency of the damper 4 is a point in time 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. 7) as shown in FIG. Is calculated as the reciprocal of a value obtained by doubling this elapsed time t1. When the stroke speed Ss of the damper 4 exceeds the threshold before the half period t2 of the unsprung resonance frequency has elapsed since the stroke speed Ss finally exceeded the threshold, the damping force control unit 50 It is determined that vibration at an unsprung resonance frequency or higher is occurring (traveling on a rough road). Further, if the stroke speed Ss of the damper 4 does not exceed the threshold value even after the half period t2 of the unsprung resonance frequency has elapsed since the last time the stroke speed Ss exceeded the threshold value, it is higher than the unsprung resonance frequency of the damper 4. It is determined that there is no vibration (running on a good road). The threshold value used for the rough road determination process may be set to different values for the front wheels and the rear wheels, or may be increased or decreased according to the vehicle speed or the target damping force. The rough road determination process includes the reversal cycle of the stroke speed Ss, the vertical acceleration of the vehicle body 1 and its reversal cycle, the vertical acceleration and reversal cycle of the wheel 3, the reversal cycle of the longitudinal acceleration of the vehicle body 1, and the lateral acceleration of the vehicle body 1. You may perform based on an inversion period etc.

The damping force control unit 50 further determines whether roll control or pitch control is performed in step S22 when the determination in step S21 is No (that is, when traveling on a good road). In this embodiment, it is determined that roll control is performed when the differential value Gy of the lateral acceleration is equal to or greater than a predetermined roll determination threshold value Gyth (for example, 2.5 m / s ³ ), and the differential value Gx of the longitudinal acceleration is determined. When a predetermined pitch determination threshold Gxth (for example, 1.5 m / s ³ ) or more is reached, it is determined that pitch control is performed. Whether or not roll control or pitch control is performed is determined 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. May be performed.

  If the determination in step S22 is No (when skyhook control is performed), the damping force control unit 50 sets the first determination threshold value Ssth1 to a standard value in step S23, and the determination in step S22 is Yes. If there is (when roll control or pitch control is performed), the first determination threshold value Ssth1 is set to the minimum value in step S24. On the other hand, when the determination in step S21 is Yes (that is, when traveling on a rough road), the damping force control unit 50 sets the first determination threshold value Ssth1 to the maximum value in step S25.

  Next, the damping force control unit 50 determines whether or not the mode switch 14 is in the sport position in step S26, and if this determination is Yes, the reduction coefficient K1 (for example, the first determination threshold value Ssth1 is determined in step S27). , 0.8). If the determination in step S26 is No, the damping force control unit 50 determines whether or not the mode switch 14 is in the comfort position in step S28. If this determination is Yes, the damping control unit 50 determines in step S29. The 1 determination threshold value Ssth1 is multiplied by an increase coefficient K2 (eg, 1.2). When the determinations in steps S26 and S28 are both No (that is, when the mode switch 14 is in the normal position), the damping force control unit 50 keeps the first determination threshold value Ssth1 as it is.

<Second threshold setting process>
The damping force control unit 50 executes a second threshold setting process whose procedure is shown in the flowchart of FIG. 8 in step S6 of FIG. When the second threshold value setting process is started, the damping force control unit 50 first performs the rough road determination described above in step S31 of FIG. 8, and when this determination is No (that is, when traveling on a good road). In step S32, it is determined whether roll control or pitch control is performed. When the determination in step S32 is No (when skyhook control is performed), the damping force control unit 50 sets the second determination threshold value Ssth2 to the minimum value in step S33, and the determination in step S32 is performed. If Yes (when roll control or pitch control is performed), the second determination threshold value Ssth2 is set to the maximum value in step S34.

  On the other hand, when the determination in step S31 is Yes (that is, when traveling on a rough road), the damping force control unit 50 determines whether roll control or pitch control is performed in step S35. If the determination in step S35 is No (when skyhook control is performed), the damping force control unit 50 sets the second determination threshold value Ssth2 to the minimum value in step S36, and the determination in step S35 is performed. If Yes (when roll control or pitch control is performed), the second determination threshold value Ssth2 is set to the maximum value in step S37.

  Next, the damping force control unit 50 determines whether or not the mode switch 14 is in the sport position in step S38. If this determination is Yes, the increase coefficient K3 (for example, the second determination threshold value Ssth2 is determined in step S39). , 1.3). If the determination in step S38 is No, the damping force control unit 50 determines whether or not the mode switch 14 is in the comfort position in step S40. If this determination is Yes, the damping force control unit 50 determines in step S41. 1 determination threshold value Ssth1 is multiplied by a reduction coefficient K4 (for example, 0.7). When the determinations in steps S38 and S40 are both No (that is, when the mode switch 14 is in the normal position), the damping force control unit 50 keeps the second determination threshold value Ssth2 as it is.

  Since the first determination threshold value Ssth1 and the second determination threshold value Ssth2 are individually set, the standard value and the minimum value may be the same or different from each other.

<Target current setting process>
The damping force control unit 50 executes a target current setting process whose procedure is shown in the flowchart of FIG. 9 in step S13 of FIG. When the target current setting process is started, the absolute values | Dsh |, | Dr |, | Dp | of the three control target values Dsh, Dr, Dp are calculated in step S51 of FIG. As shown by the solid line, the control target value selected when the stroke speed is on the expansion side (hereinafter referred to as the expansion side target value: skyhook control target value Dsh in this embodiment) and the stroke speed are on the contraction side. The control target value (hereinafter referred to as the contraction-side target value: pitch control target value Dp in this embodiment) that is selected from the control target value that is larger than the control target value (in the case of FIG. The control target value Dsh) is adopted as the target damping force Dtgt.

[Ryoji]
Next, the damping force control unit 50 performs the rough road determination described above in step S53. If this determination is No (that is, if the vehicle is traveling on a good road), roll control or pitch control is performed in step S54. (Whether the roll control target value Dr or the pitch control target value Dp is adopted as the target damping force Dtgt) is determined.

(Skyhook control)
When the determination in step S54 is No (that is, when traveling on a good road while performing skyhook control), the damping force control unit 50 determines the target from the first target current map shown in FIG. 11 in step S55. The current Itgt is searched. As can be seen from the figure, when driving on a good road while performing skyhook control, if the absolute value of the stroke speed Ss is smaller than the first determination threshold Ssth1 (standard value) (the stroke speed Ss is -Ssth1). ˜Ssth1), the target current Itgt is determined only by the target damping force Dtgt (that is, without depending on the stroke speed Ss). Further, if the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the target current Itgt is not output. As a result, even when the target damping force Dtgt changes in a short cycle due to noise mixed in the detection signals of the sensors 10 to 13, the change in the target current Itgt is suppressed in a relatively wide determination range, and the ride comfort Improvement is realized. In addition, when the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the target current Itgt is not output except for a relatively narrow determination range, so that the skyhook control is not easily inhibited.

(Roll control / Pitch control)
When the determination in step S54 is Yes (that is, when the vehicle is traveling on a good road while performing roll control or pitch control), the damping force control unit 50 performs the second target current map shown in FIG. 12 in step S56. From the target current Itgt. As can be seen from the figure, when traveling on a good road while performing roll control and pitch control, if the absolute value of the stroke speed Ss is smaller than the first determination threshold Ssth1 (minimum value) (the stroke speed Ss is -If it is in the determination range of Ssth1 to Ssth1), the target current Itgt is determined only by the target damping force Dtgt (that is, not depending on the stroke speed Ss). Even if the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the absolute value of the stroke speed Ss is smaller than the second determination threshold value Ssth2 (maximum value) (the stroke speed Ss is -Ssth2 to Ssth2). If it is within the determination range, the target current Itgt is set regardless of the direction of the stroke speed Ss. Thereby, even when the stroke speed Ss is relatively small, the target current Itgt does not become unnecessarily small, and roll control and pitch control are performed smoothly.

[Bad road]
On the other hand, when the determination in step S53 is Yes (that is, when traveling on a rough road), the damping force control unit 50 determines whether roll control or pitch control is performed in step S57 (roll control target value). Whether Dr or the pitch control target value Dp is adopted as the target damping force Dtgt is determined.

(Skyhook control)
When the determination in step S57 is No (that is, when driving on a rough road while performing skyhook control), the damping force control unit 50 determines the target from the third target current map shown in FIG. 13 in step S58. The current Itgt is searched. As can be seen from the figure, when the vehicle is traveling on a rough road while performing skyhook control, if the absolute value of the stroke speed Ss is smaller than the first determination threshold value Ssth1 (maximum value) (the stroke speed Ss is -Ssth1). ˜Ssth1), the target current Itgt is determined only by the target damping force Dtgt (that is, without depending on the stroke speed Ss). Even if the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the absolute value of the stroke speed Ss is smaller than the second determination threshold value Ssth2 (minimum value) (the stroke speed Ss is -Ssth2 to Ssth2). If it is within the determination range, the target current Itgt is set regardless of the direction of the stroke speed Ss. As a result, even when the target damping force Dtgt changes in a short cycle due to noise mixed in the detection signals of the sensors 10 to 13, the change in the target current Itgt is suppressed in a wide determination range, thereby improving riding comfort. Is realized. In addition, when the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the target current Itgt is not output except for a relatively narrow determination range, so that the skyhook control is not easily inhibited.

(Roll control / Pitch control)
When the determination in step S57 is Yes (that is, when traveling on a rough road while performing roll control or pitch control), the damping force control unit 50 performs the fourth target current map shown in FIG. 14 in step S59. From the target current Itgt. As can be seen from the figure, when the vehicle is traveling on a rough road while performing roll control or pitch control, if the absolute value of the stroke speed Ss is smaller than the first determination threshold value Ssth1 (maximum value) (the stroke speed Ss is -If it is in the determination range of Ssth1 to Ssth1), the target current Itgt is determined only by the target damping force Dtgt (that is, not depending on the stroke speed Ss). Even if the direction of the stroke speed Ss and the direction of the target damping force Dtgt are different, the absolute value of the stroke speed Ss is smaller than the second determination threshold value Ssth2 (maximum value) (the stroke speed Ss is -Ssth2 to Ssth2). If it is within the determination range, the target current Itgt is set regardless of the direction of the stroke speed Ss. Thereby, even when the stroke speed Ss is relatively high, the target current Itgt does not become unnecessarily small, and roll control and pitch control are performed smoothly.

  In this embodiment, when the target damping force is on the expansion side as shown in FIG. 15, even if the stroke direction changes at a very short cycle between the expansion side and the contraction side as shown in FIG. A desired target current Itgt can be obtained, and a decrease in control responsiveness due to a drive current rising delay or the like can be effectively suppressed. As a result, the damper 4 stably generates an appropriate damping force, thereby improving the handling stability and the riding comfort. In addition, as shown in the lower part of FIGS. 11 to 14, 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.

  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 variable damper and the drive current is used as the control amount. However, for example, the present invention is applied to the mechanical type 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.

4 Damper 7 Damper ECU
DESCRIPTION OF SYMBOLS 50 Damping force control part 52 Target damping force setting part 53 Target damping force selection part 54 Drive current generation part 56 Skyhook control part (Target damping force setting means)
57 Roll control unit (target damping force setting means)
58 Pitch control unit (Target damping force setting means)
V car

Claims (3)

A control device for controlling the damping force of a damping force variable damper provided for suspension of a vehicle body,
Stroke speed acquisition means for acquiring the stroke speed of the damping force variable damper, acceleration detection means for detecting at least one of lateral acceleration and longitudinal acceleration of the vehicle body, and target damping force based on the motion state or road surface state of the vehicle body Target damping force setting means for setting the control amount, and control amount setting means for setting the control amount of the damping force variable damper,
The control amount setting means includes determination range setting means for setting a first determination range including 0 with respect to the stroke speed based on a motion state or a road surface state of the vehicle body, and a traveling road surface based on a change in the stroke speed. Road surface condition determining means for determining whether the vehicle is a good road or a bad road, and attitude change determining means for determining whether the attitude change of the vehicle body is abrupt based on the lateral acceleration or the longitudinal acceleration of the vehicle body And when the stroke speed is outside the first determination range, the control amount is set based on the target damping force and the stroke speed, while the stroke speed is within the first determination range. In this case, the control amount is set based only on the target damping force,
The determination range setting means includes
When it is determined that the road surface is a good road and the posture change is determined to be abrupt, the first determination range is set to a predetermined reduction determination range,
When it is determined that the traveling road surface is a bad road, the first determination range is set to a predetermined expansion determination range,
When it is determined that the traveling road surface is a good road and the posture change is determined not to be abrupt, the first determination range is set between the reduction determination range and the expansion determination range. Control device for variable damping force damper. The determination range setting means sets a second determination range including 0 for the stroke speed when the posture change is determined to be abrupt.
When the stroke speed is within the second determination range, the control amount setting means regards the direction of the target damping force and the stroke direction of the damping force variable damper as being the same, thereby determining the damping force variable damper. 2. The damping force variable damper control device according to claim 1, wherein the same control amount is set for the expansion side and the contraction side. It further comprises attenuation mode switching means that is switched by the driver,
The control amount setting means enlarges or reduces at least one of the first determination range and the second determination range according to a switching state of the attenuation mode switching means. The damping force variable damper control device described in 1.

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