JP5043751B2 - Control device for damping force variable damper - Google Patents

Description

  The present invention relates to a control device that controls a current-controlled damping force variable damper, and more particularly to a technique for suppressing noise caused by noise in a sensor system.

  In recent years, various types of cylindrical dampers that constitute suspensions for automobiles have variable damping force that can variably control the damping force according to the motion state of the automobile, etc. in order to achieve both high driving stability and ride comfort. Has been developed. 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 mainstream, but the structure is simplified and control response is improved. In order to achieve this, the viscosity of the MRF is adjusted by using a magnetorheological fluid (Magneto-Rheological Fluid: hereinafter referred to as MRF) as the hydraulic oil and a magnetic fluid valve (hereinafter referred to as MLV) provided on the piston. What is controlled (hereinafter referred to as MRF type damping force variable damper) has appeared (see Patent Document 1).

Generally, when controlling the MRF type damping force variable damper, the target damping force setting means in the damper control device sets the target damping force for each wheel based on the lateral acceleration and longitudinal acceleration of the vehicle body, and then sets the target current. The means sets the target current (for example, 0A to 5A) for each MLV based on the target current map shown in FIG. As can be seen from FIG. 5, in the low damping force generation region (near 0A to 2A), the amount of change is small relative to the change amount of the target damping force, and the high damping force generation region (near 2A to 5A). In FIG. 5, the amount of change is larger than the amount of change in the target damping force.
JP 2006-273223 A

  However, in the MRF type damping force variable damper, for example, when the applied current changes from 0 A to 5 A, the actual current is aligned between 0 A and 2 A in the magnetic flux in the MLV yoke as shown in FIG. It increases in a relatively short time because of its high speed, and it takes a relatively long time from 2A to 5A because of the saturation of the magnetic flux alignment speed. Therefore, in combination with a small change in the target current in the low damping force generation region (that is, a large change in the damping force with respect to the change in the target current), the damping force immediately after the change in the applied current as shown in FIG. However, there is a problem that abnormal noise due to so-called thrusting is generated from the suspension or the durability of the suspension components (rubber bushes, etc.) is lowered.

  Therefore, the present applicant prevents the sudden increase in damping force by reducing the initial increase rate of the applied current when the target current is increased, thereby generating abnormal noise from the suspension and reducing the durability of the suspension components. An invention that can be suppressed has been filed as Japanese Patent Application No. 2008-058396. According to the present invention, in order to generate the target damping force in the damping force variable damper, the target current is determined based on the target damping force and the stroke speed of the damper as before, but the current increases according to the vehicle speed. By setting the vehicle speed gain that changes the rate and calculating the applied current so that the initial change speed becomes small, the sudden rise of the current is suppressed and the generation of abnormal noise due to the sudden increase in damping force is prevented. Yes.

  However, since the MRF type damping force variable damper has good control response, even if the initial increase rate of the applied current is reduced, positive and negative noise is included in the detected value of the stroke speed that is the basis of the target current. In this case, the following problems occur. That is, when the stroke speed is high, there is not much influence due to noise, but when the stroke speed is low, noise may occur in the suspension. This is because when the stroke speed is low, the noise becomes relatively large, and the detected value of the stroke speed may be frequently switched between positive and negative. Then, when setting the target current based on the stroke speed, since the target current is treated as 0 when the detected value is negative in the map of FIG. 5, the target current is output intermittently, such as a damper mount. An abnormal noise due to backlash occurs.

  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 variable damping force damper that suppresses abnormal noise caused by noise in a sensor system.

  A first invention is a control device for controlling a current-controlled variable damping force damper provided for suspension of a vehicle body, and sets a target damping force of the variable damping force damper based on a motion state of the vehicle body. Based on the target damping force setting means, the stroke speed detecting means for detecting the stroke speed of the damping force variable damper, the setting result of the target damping force setting means and the detection result of the stroke speed acquisition means, the damping force variable A target current setting means for setting a target current for the damper, and an applied current setting means for setting an applied current to the damping force variable damper based on a setting result of the target current setting means, the applied current setting means Is characterized in that when the target current changes, the rate of change of the applied current is set according to the stroke speed.

  Further, the second invention is the control apparatus for the damping force variable damper described in the first invention, wherein the applied current setting means reduces the change rate of the applied current as the stroke speed decreases, The rate of change of the applied current is increased as the stroke speed increases.

  According to the first invention, even if the target current changes due to a change in the target damping force, the rate of change of the applied current is set according to the stroke speed, so that the suspension speed from the suspension caused by the noise of the stroke speed detecting means can be reduced. Abnormal noise generation and deterioration of the durability of the suspension components are suppressed. Further, according to the second invention, in the low stroke speed region, the noise caused by the intermittent current output is suppressed by being affected by the noise of the stroke speed detecting means, while the high stroke speed region. Then, by improving the current response without impressing the noise of the stroke speed detection means, the high response of the MRF type damping force variable damper can be effectively utilized.

Hereinafter, an embodiment in which the present invention is applied to a four-wheel passenger car will be described in detail with reference to the drawings.
FIG. 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 damper control device according to the embodiment. is there.

<< Configuration of Embodiment >>
<Overall 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 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. The vehicle V includes a vehicle speed sensor 9 that detects a vehicle speed, a lateral G sensor 10 that detects lateral acceleration, a longitudinal G sensor 11 that detects longitudinal acceleration, a stroke sensor 12 that detects the displacement of the damper 4, and the like. Each wheel 3 is provided with a vertical G sensor 13 that detects vertical acceleration in the vicinity of the wheel house.

  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)) It is connected to each sensor 9-13.

<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.

  The piston 26 is provided with an annular communication passage 39 that allows the upper oil chamber 24 and the lower oil chamber 25 to communicate with each other, and an MLV coil 40 that is disposed inside the annular communication passage 39. When an electric current is supplied from the ECU 7 to the MLV coil 40, a magnetic field is applied to the MRF that flows through the annular communication path 39, and the ferromagnetic fine particles form chain clusters, 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 9 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 target current setting unit 54 that sets a target current for each damper 4 (MLV coil 40) according to the target damping force, the detection result of the stroke sensor 12, and the detection result of the vehicle speed sensor 9, and the setting result of the target current setting unit 54 An applied current setting unit 55 for setting the applied current based on the output current, and an output interface 56 for outputting the applied current set by the applied current setting unit 55 to each damper 4; It is al configuration. The damping force setting unit 52 includes a skyhook control unit (target damping force setting unit) 57 used for skyhook control, a roll control unit (target damping force setting unit) 58 used for roll control, and a pitch. A pitch control unit (target damping force setting means) 59 used for control is accommodated.

<< Operation of 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, 2 ms). When the damping force control is started, the damper control device 50 inputs the acceleration of the vehicle body 1 obtained from the lateral G sensor 10, the front / rear G sensor 11, and the vertical G sensor 13 and the vehicle speed sensor 9 in step S <b> 1 of FIG. 4. The motion state of the vehicle V is determined based on the vehicle body speed, the steering speed input from a steering angle sensor (not shown), 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 stroke speed Ss of each damper 4 is a positive value in step S5, and if this determination is Yes (that is, the damper 4 operates to the extension side). In step S6, the target damping force Dtgt having the largest value among the three control target values Dsh, Dr, Dp is set in step S6. Further, when the determination in step S5 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 S7. Is set as the target damping force Dtgt.

  When the target damping force Dtgt is set in step S6 or step S7, the damper controller 50 searches / sets the target current Itgt from the target current map of FIG. 5 in step S8. Next, the damper control device 50 determines whether or not the current vehicle speed v input from the vehicle speed sensor 9 in step S9 is higher than a vehicle speed determination threshold vth (for example, 20 km / h). If the determination in step S9 is Yes, the damper control device 50 sets the relatively large medium / high speed gain Gvh to the vehicle speed gain Gv in step S10, and the determination in step S9 is No. In step S11, a relatively small low speed gain Gvl is set as the vehicle speed gain Gv.

なお、本実施形態の場合、パラメータＰは０．８とした。 When the setting of the vehicle speed gain Gv is completed in step S10 or step S11, the damper control device 50 reduces the changing speed in the low current region in step S12 based on the target current Itgt and the vehicle speed gain Gv set in step S8. Thus, the target current Itgt is corrected, and the vehicle speed correction current Iv is calculated / set. Specifically, by using the applied current Iv _n and parameter P of the previous, it calculates a present vehicle speed correction current Iv n _{+ 1} based on the following equation (1).

In the present embodiment, the parameter P is set to 0.8.

  As a result, as shown in FIG. 6, the vehicle speed correction current Iv in the medium / high speed region has an increase rate in the low damping force generation region (low current region) smaller than the increase rate in the high damping force generation region (high current region). As such, it will change at a relatively high rate. In addition, as shown in FIG. 7, the vehicle speed correction current Iv in the low speed region also has an increase rate in the low damping force generation region smaller than that in the high damping force generation region. It will change at a low speed. As a result, as shown in FIG. 8, the actual current Ir flowing through the MLV coil 40 corresponding to the vehicle speed correction current Iv increases substantially linearly with a predetermined increase amount, and the damping force in the medium-high speed range. The rise of the vehicle body 1 is relatively fast and the pitching of the vehicle body 1 is effectively suppressed, while the rise of the damping force in the low speed region is relatively slow and the generation of abnormal noise from the suspension 5 is effectively suppressed. .

  Here, when the stroke speed Ss changes at a relatively large value, for example, when the vehicle speed correction current Iv is set by setting the medium speed / high speed gain Gvh to the vehicle speed gain Gv, the detection result of the stroke sensor 12 includes noise. 9, the vehicle speed correction current Iv and the actual current are not significantly affected by the noise reflected in the target current Itgt, as shown in FIG. Also, when the low speed gain Gvl is set to the vehicle speed gain Gv and the vehicle speed correction current Iv is set, the response speed is made faster, so that the influence of noise does not cause a problem.

  However, when the stroke speed Ss changes at a relatively small value, the sign of the stroke speed Ss may be frequently changed due to noise included in the detection result of the stroke sensor 12, as shown in FIG. Then, when setting the target current Itgt from the target current map of FIG. 5 in step 8, if the stroke speed Ss becomes a negative value even though the target damping force Dtgt is a positive value, the target current Itgt Is set to 0. Therefore, when the vehicle speed v is higher than the vehicle speed determination threshold vth, that is, when the relatively large medium-high speed gain Gvh is set to the vehicle speed gain Gv, the vehicle speed correction current Iv set in step 16 is As shown in FIG. 11, the tooth shape changes.

  Accordingly, the damper control device 50 determines whether or not the stroke speed Ss is higher than a stroke speed determination threshold Sth (for example, 0.05 m / s) in step S13. If the determination in step S13 is Yes, the damper control device 50 sets the relatively large medium / high speed gain Gsh to the stroke speed gain Gs in step S14, and the determination in step S13 is No. In this case, a relatively small low speed gain Gsl is set as the stroke speed gain Gs in step S15.

  When the setting of the stroke speed gain Gs is completed in step S14 or step S15, the damper control device 50 reduces the stroke speed Ss in step S16 based on the vehicle speed correction current Iv and the stroke speed gain Gs set in step S12. The applied current Y is corrected and the applied current Y is calculated / set so that the change rate of the applied current becomes smaller as the stroke speed Ss becomes larger and the change rate of the applied current becomes larger as the stroke speed Ss becomes higher. Next, the damper control device 50 outputs the applied current Y to the MLV coil 40 of each damper 4 in step S17.

  As a result, the vehicle speed correction current Iv shown in FIG. 11 is set so as to be influenced by noise included in the detection result of the stroke sensor 12 in the low stroke speed region as shown in FIG. Will decrease. Thereby, in the low stroke speed region, abnormal noise generated from the suspension is effectively suppressed, and a decrease in the durability of the suspension components is also suppressed. On the other hand, in the high stroke speed region, the damping force control is performed by effectively utilizing the speed of the current response without the noise of the stroke sensor 12 being smoothed.

  In the present embodiment, by adopting the above-described configuration, the damping force of each damper 4 changes linearly and smoothly as shown in FIG. 8, and the stroke sensor 12 of the stroke sensor 12 as shown in FIG. The comb-like output due to noise was reduced, and the generation of abnormal noise from the suspension due to sudden increase in damping force and the occurrence of abnormal noise from the suspension due to comb-like output were both suppressed. In addition, a decrease in the durability of the suspension component is suppressed.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the present invention is applied to an MRF type damping force variable damper, but may be applied to a damping force variable damper using a magnetic fluid or a mechanical damping force variable damper. Also, in setting the applied current, a calculation method other than those described in the embodiment may be employed, or a method such as searching from a map may be employed. In addition, as long as it does not deviate from the gist of the present invention, the specific configuration of the damper control device, the specific procedure of control, and the like can be appropriately changed.

Schematic configuration diagram of a four-wheeled vehicle according to an embodiment Vertical sectional view of a damper according to an embodiment The block diagram which shows schematic structure of the damper control apparatus which concerns on embodiment The flowchart which shows the procedure of damping force control which concerns on embodiment Target current map according to the embodiment The graph which shows the relationship between the 1st correction | amendment electric current and the actual electric current in the middle-high speed area which concerns on embodiment The graph which shows the relationship between the 1st correction | amendment electric current and real current in the low speed area which concerns on embodiment. The graph which shows the change of damping force concerning an embodiment The graph which shows the relationship between the 1st correction | amendment electric current and real current in the medium-high-speed stroke speed area | region which concerns on embodiment. The graph which shows the stroke speed which concerns on embodiment Graph showing the first correction current according to the embodiment Graph showing the second correction current according to the embodiment A graph showing the relationship between applied current and actual current in a conventional device Graph showing the change of damping force in the conventional device

Explanation of symbols

1 Car body 4 Damper 5 Suspension 12 Stroke sensor (Stroke speed detection means)
50 damper control device 52 damping force setting unit (target damping force setting means)
53 Target damping force selection unit 54 Target current setting unit (target current setting means)
55 Applied current setting section (applied current setting means)
V car

Claims (1)

A control device for controlling a current-controlled variable damping force damper provided for suspension of a vehicle body,
Target damping force setting means for setting a target damping force of the damping force variable damper based on the motion state of the vehicle body;
Stroke speed detection means for detecting the stroke speed of the damping force variable damper;
Target current setting means for setting a target current for the variable damping force damper based on the setting result of the target damping force setting means and the detection result of the stroke speed detecting means;
An applied current setting means for setting an applied current to the damping force variable damper based on a setting result of the target current setting means;
The applied current setting means sets the rate of change of the applied current so that it decreases as the stroke speed decreases, and increases as the stroke speed increases when the target current changes. A damping force variable damper control device.

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