JP2008189025A - Damping force variable damper attached vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force variable damper attached vehicle with riding comfort and steering stability improved in turning running. <P>SOLUTION: A roll calculation control part 56 judges whether a second base value Dbase2 is not less than a first base value Dbase1 in step S7 or not. If this judgment is No, the part completes this processing while a target damping force is the first base value Dbase1 in step S8. Also, the judgment in step S7 is Yes, the roll calculation control part 56 completes this processing while the target damping force is the second base value Dbase2 in step S9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle equipped with a variable damping force damper, and more particularly to a technique for improving riding comfort and steering stability during turning.

2. Description of the Related Art In recent years, various types of cylinder dampers used in automobile suspensions have been developed in which a damping force variable damper capable of variable damping force control is installed in order to improve ride comfort and handling stability. 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 is the mainstream, but the structure is simplified and the control response is improved. In order to achieve this, there has also appeared a technique in which a magnetorheological fluid is used as a working fluid and the viscosity of the magnetorheological fluid is controlled by a magnetorheological valve formed on a piston (see Patent Documents 1 and 2). For vehicles equipped with a variable damping force damper, control delay can be suppressed by setting the target damping force based on the differential value of the vehicle body acceleration (lateral acceleration and longitudinal acceleration) when performing damping force control. Is known (see Patent Document 3).
JP 2006-281876 A JP 2006-321258 A JP 2006-69527 A

  In the vehicle equipped with the damping force variable damper of Patent Document 3, the damping force of the damper is increased at the time when the absolute value of the differential value of the vehicle body acceleration becomes large (that is, immediately before the vehicle body starts rolling or pitching). It is possible to effectively suppress changes in the behavior of the vehicle body at the time of driving or sudden acceleration. However, on the other hand, there is a possibility that the behavior of the vehicle body may change suddenly because the damping force of the damper is almost lost during turning traveling or slow deceleration traveling where the stroke speed of the damper hardly changes.

  For example, when turning, as shown in FIG. 8, the driver starts turning the steering wheel, and the lateral acceleration and the stroke difference between the left and right dampers increase linearly (first section: to → ta in the figure) Transition to circular turning, only the stroke difference between the left and right dampers increases under a certain lateral acceleration (second section: ta → tb in the figure), the driver starts to return the steering wheel, and the lateral acceleration and the left and right dampers The stroke difference decreases linearly (third section: tb → tc in the figure), and after shifting to straight running and the lateral acceleration becomes zero, only the stroke difference between the left and right dampers decreases (fourth section: in the figure). , Tc → td). 8 indicates the relationship between the lateral acceleration and the stroke difference between the left and right dampers when the damper has no damping force.

  In this case, the differential value of the lateral acceleration becomes a positive constant value in the first interval, becomes 0 in the second interval, becomes a negative constant value in the third interval, and becomes 0 again in the fourth interval. Therefore, as shown in FIG. 9, a constant target damping force is set for the damper in the first section and the third section, while the target damping force is 0 in the second section and the fourth section. As a result, the stroke difference between the left and right dampers changes linearly in the first section and the third section, but in the second section and the fourth section, at the start time (portion indicated by a broken circle in FIG. 9). Since the suspension is displaced by the spring force of the spring (that is, the left and right dampers are stroked), the suspension changes rapidly. As a result, the roll angle of the vehicle body changes suddenly during the turn, giving the driver a sense of discomfort.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a vehicle equipped with a variable damping force damper that improves ride comfort and steering stability during turning.

  According to the first aspect of the present invention, there is provided a damping force variable damper that is installed in each of a plurality of suspensions and attenuates vertical vibrations of a vehicle body suspended from the suspensions, a vehicle body acceleration detection means that detects vehicle body acceleration, and the damping force variable. A first damping of the variable damping force damper based on the differential value of the detection result of the vehicle body acceleration detecting means and the stroke amount detection means for detecting the stroke amount of the damping force variable damper. A base value setting means for setting a force base value, an actual stroke difference calculating means for calculating an actual stroke difference between the damping force variable dampers based on a detection result of the stroke amount detecting means, the actual stroke difference and the vehicle body Second base value setting means for setting a second damping force base value of the damping force variable damper based on the acceleration; Based on the force base value and the second damping force base value, characterized in that a target damping force setting means for setting a target damping force of the variable damping force damper.

  The invention according to claim 2 further includes a map in which an ideal stroke difference between the damping force variable damper corresponding to the vehicle body acceleration is stored in the vehicle equipped with the damping force variable damper according to claim 1, The second base value setting means sets the second damping force base value based on the actual stroke difference and the ideal stroke difference.

  According to a third aspect of the present invention, in the vehicle equipped with the damping force variable damper according to the first or second aspect, the actual stroke difference calculating means calculates a frequency higher than a predetermined frequency when calculating the actual stroke difference. In this case, the detection result of the stroke amount detecting means input in step S is not used.

  According to a fourth aspect of the present invention, there is provided the variable damping force damper-equipped vehicle according to any one of the first to third aspects, wherein the target damping force setting means is an absolute value of the first damping force base value. When the value and the absolute value of the second damping force base value are both equal to or less than a predetermined value, the first damping force base value and the second damping force base value are set in setting the target damping force of the damping force variable damper. It is not used.

  The invention of claim 5 is a vehicle equipped with a variable damping force damper according to any one of claims 1 to 4, further comprising stroke difference calibration means for calibrating the actual stroke difference, wherein the stroke The difference calibrating means sets the actual stroke difference to 0 when the actual stroke difference continues the same value over a predetermined time.

  According to the first aspect of the invention, for example, the first damping force base value is compared with the second damping force base value, and the larger value is set as the target damping force, so that the lateral acceleration differential value becomes zero. Even in such a traveling state, the stroke difference between the left and right dampers is unlikely to change suddenly. According to the invention of claim 2, the second damping force base value can be set by a relatively simple calculation. According to the invention of claim 3, it is possible to prevent the damping force from being increased unnecessarily and deteriorating the riding comfort and the like when traveling on a rough road where the expansion and contraction of the damper becomes intense. According to the invention of claim 4, even if noise is mixed in the detection signals of the vehicle body acceleration detecting means and the stroke amount detecting means, the damping force is unnecessarily increased when traveling straight on a flat road, so Is prevented from getting worse. In addition, according to the invention of claim 5, for example, by making the predetermined time sufficiently long, the difference in the suspension components can be obtained with the stroke difference during straight traveling without using the stroke difference between the left and right dampers during turning. It is possible to calibrate stroke differences due to changes in the number of passengers.

  Hereinafter, embodiments in which the present invention is applied to a four-wheeled vehicle will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment, FIG. 2 is a longitudinal sectional view of a damper according to the embodiment, and FIG. 3 is a block diagram illustrating a schematic configuration of a damping force control device according to the embodiment. 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 generically referred to as wheel 3.

  As shown in FIG. 1, a vehicle body 1 of an automobile (vehicle) V has wheels 3 with tires 2 mounted on the front, rear, left and right thereof. These wheels 3 are each provided with a suspension arm 4, a spring 5, and a variable damping force. It is suspended from the vehicle body 1 by a suspension 7 composed of a type damper (hereinafter simply referred to as a damper) 6 or the like. The vehicle V includes an ECU (Electronic Control Unit) 8 used for various controls, a vehicle speed sensor 9 that detects a vehicle speed, a lateral G sensor (vehicle acceleration detection means) 10 that detects lateral acceleration, and longitudinal acceleration. A front-rear G sensor 11 for detecting, a yaw rate sensor 12 for detecting yaw rate, and the like are installed at appropriate positions of the vehicle body 1. Further, in the vehicle V, a vertical G sensor 13 for detecting vertical acceleration in the vicinity of the wheel house and a stroke sensor (stroke amount detecting means) 14 for detecting the stroke amount of the damper 6 are installed for each wheel 3. .

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

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

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

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

<Schematic configuration of damping force control device>
As shown in FIG. 2, the ECU 8 includes a damping force control device 50 that controls the damper 6. The damping force control device 50 includes a damping force setting unit (target) that sets the target damping force of each damper 6 based on the input interface 51 to which each of the sensors 9 to 14 is connected and the detection signals input from the sensors 9 to 14. (A damping force setting means) 52, a driving current generating unit 53 that generates a driving current to each damper 6 (MLV coil 42) according to the target damping force input from the damping force setting unit 52, and a driving current generating unit 53 The output interface 54 outputs the generated drive current to each damper 6. The damping force setting unit 52 includes a skyhook calculation control unit 55 used for skyhook control, a roll calculation control unit 56 used for roll control, a pitch calculation control unit 57 used for pitch control, and a stroke. A stroke difference calibration unit (stroke difference calibration means) 58 for calibrating the difference is accommodated.

<< Operation of Embodiment >>
When the vehicle V starts driving, the damping force setting unit 52 in the damping force control device 50 is based on the detection signals input from the sensors 9 to 14, the skyhook calculation control unit 55, the roll calculation control unit 56, the pitch calculation. Various calculations are executed in the controller 57. Then, the damping force setting unit 52 sets the target damping force of each damper 6 by multiplying those calculation results by a predetermined gain or performing high selection. The drive current generator 53 generates a drive current corresponding to the target damping force set by the damping force setting unit 52 and outputs it to the MLV coil 42 of each damper 6. As a result, the vertical movement of the vehicle body 1 is suppressed even when there is a relatively large unevenness on the road, while rolling and pitching of the vehicle body 1 during turning and acceleration / deceleration are suppressed, so Improves.

<Roll control>
The roll calculation control unit 56 repeatedly executes roll control whose procedure is shown in the flowchart of FIG. 4 at a predetermined processing interval (for example, 10 ms).

  When roll control is started, the roll calculation control unit 56 reads the lateral acceleration GY input from the lateral G sensor 10 in step S1 in FIG. 4 and the stroke amounts SL and SR of the left and right dampers 6 input from the stroke sensor 14. Next, after calculating the lateral acceleration differential value DY ′ in step S2, the roll calculation control unit 56 calculates a first damping force base value (hereinafter referred to as the first base value) in step S3 based on the lateral acceleration differential value DY ′. (Abbreviated) Dbase1 is calculated.

Next, the roll calculation control unit 56 calculates the actual stroke difference DSr from the left and right stroke amounts SL, SR in step S4, and then in step S5, a second damping force base value (hereinafter abbreviated as a second base value). Dbase2 is calculated. The second base value Dbase2 is obtained by searching an ideal stroke difference (stroke difference between the left and right dampers 6 when there is no damping force) DSi corresponding to the current lateral acceleration GY from the lateral acceleration-ideal stroke difference map shown in FIG. It is calculated by multiplying the value obtained by subtracting the actual stroke difference DSr from the ideal stroke difference DSi by the spring constant K of the spring 5.
Dbase2 = K · (DSi-DSr)

  When the calculation of the second base value Dbase2 is completed, the roll calculation control unit 56 determines that the absolute value | Dbase1 | of the first base value Dbase1 and the absolute value | Dbase2 | of the second base value Dbase2 are both predetermined in step S6. It is determined whether or not it is equal to or greater than the determination threshold value Dth, and if this determination is No, the current process is terminated without setting the target damping force Dtgt based on the first base value Dbase1 and the second base value Dbase2. . This is because, when noise is mixed in the detection signals of the lateral G sensor 10 and the stroke sensor 14, the first base value Dbase1 and the second base value Dbase2 are calculated even when the vehicle travels straight on a flat road. This is because the force is unnecessarily increased and the ride comfort is deteriorated.

  If the determination in step S6 is Yes, the roll calculation control unit 56 determines whether or not the second base value Dbase2 is greater than or equal to the first base value Dbase1 in step S7, and if this determination is No, In step S8, the target damping force is set to the first base value Dbase1, and the current process is terminated. If the determination in step S7 is Yes, the roll calculation control unit 56 sets the target damping force as the second base value Dbase2 in step S9 and ends the current process.

  Thus, even when the lateral acceleration and the stroke difference between the left and right dampers 6 change as shown in FIG. 7 during turning, the ideal stroke difference and the actual stroke difference are different as shown in FIG. While the force for changing the roll force of the vehicle body 1 is acting, the target damping force no longer becomes 0, and the stroke difference between the left and right dampers 6 does not change abruptly. As a result, the roll angle of the vehicle body 1 does not suddenly change during turning, and the driver's uncomfortable feeling that has been a problem with conventional devices has been solved.

<Stroke difference calibration control>
In parallel with the roll control described above, the roll calculation control unit 56 repeatedly executes the stroke difference calibration control whose procedure is shown in the flowchart of FIG. 7 with a predetermined processing interval.

  When the stroke difference calibration control is started, the roll calculation control unit 56 reads the stroke amounts SL and SR of the left and right dampers 6 input from the stroke sensor 14 in step S11 of FIG. 7, and then the left and right stroke amounts SL in step S12. , SR, the actual stroke difference DSr is calculated. Next, the roll calculation control unit 56 determines whether or not the actual stroke difference DSr continues for a predetermined time (for example, 100 seconds) in step S13. If the determination is No, the roll difference control unit 56 does not calibrate the stroke difference. The process ends. Thus, even if steady circular turning is performed for a relatively long time (for example, about 10 seconds), the stroke difference is not calibrated by the stroke amounts SL and SR at that time.

  On the other hand, when the determination in step S13 is Yes, the roll calculation control unit 56 calibrates the stroke difference (that is, the actual stroke difference DSr described above is set to 0). This prevents erroneous detection of a stroke difference caused by a dimensional error of suspension components, a change in the number of passengers, a load bias, and the like.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, although the above-described embodiment is an application of the present invention to roll control, it is naturally applicable to pitch control. Moreover, although the said embodiment applies this invention of the four-wheeled vehicle provided with the MRF type damping force variable damper, this invention is a four-wheeled vehicle provided with the damping force variable damper other than MRF type. It can also be applied to two-wheeled vehicles. In the above embodiment, the larger one of the first damping force base value and the second damping force base value is selected (highly selected), but the first damping force base value and the second damping force base value are selected. A method of multiplying each value by a predetermined gain and adding them may be adopted. In addition, the specific configuration of the control device, the specific procedure of the control, and the like can be changed as appropriate without departing from the spirit of the present invention.

1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment. It is a longitudinal cross-sectional view of the damper which concerns on embodiment. It is a block diagram which shows schematic structure of the damping-force control apparatus which concerns on embodiment. It is a flowchart which shows the procedure of the roll control which concerns on embodiment. It is a lateral acceleration-ideal stroke difference map concerning an embodiment. It is a graph which shows the effect of an embodiment. It is a flowchart which shows the procedure of the stroke difference calibration control which concerns on embodiment. It is a graph which shows the relationship between the lateral acceleration at the time of turning driving | running | working, and a stroke difference. It is a graph which shows the problem of a prior art.

Explanation of symbols

1 Car body 3 Wheel 6 Damping force variable damper 7 Suspension 8 ECU
10 Lateral G sensor (vehicle acceleration detection means)
14 Stroke sensor (Stroke amount detection means)
50 Damping Force Control Device 52 Damping Force Setting Unit 57 Pitch Calculation Control Unit V Automobile

Claims (5)

A damping force variable damper that is installed on each of the suspensions and attenuates the vertical vibration of the vehicle body suspended on the suspension;
Vehicle body acceleration detecting means for detecting vehicle body acceleration;
Stroke amount detecting means provided for each of the damping force variable dampers for detecting the stroke amount of the damping force variable dampers;
Base value setting means for setting a first damping force base value of the damping force variable damper based on a differential value of a detection result of the vehicle body acceleration detecting means;
An actual stroke difference calculating means for calculating an actual stroke difference between the damping force variable dampers based on a detection result of the stroke amount detecting means;
Second base value setting means for setting a second damping force base value of the damping force variable damper based on the actual stroke difference and the vehicle body acceleration;
A damping force variable type comprising: target damping force setting means for setting a target damping force of the damping force variable damper based on the first damping force base value and the second damping force base value. Vehicle equipped with a damper. A map storing an ideal stroke difference between the damping force variable damper corresponding to the vehicle body acceleration;
2. The damping force variable damper mounting according to claim 1, wherein the second base value setting means sets the second damping force base value based on the actual stroke difference and the ideal stroke difference. vehicle.   The said actual stroke difference calculation means does not use the detection result of the said stroke amount detection means input with the frequency higher than a predetermined frequency in calculation of the said actual stroke difference, The Claim 1 or Claim 2 characterized by the above-mentioned. With a variable damping force damper. .   The target damping force setting means sets the target damping force of the variable damping force damper when both the absolute value of the first damping force base value and the absolute value of the second damping force base value are less than or equal to a predetermined value. In this case, the damping force variable damper-equipped vehicle according to any one of claims 1 to 3, wherein the first damping force base value and the second damping force base value are not used. A stroke difference calibration means for calibrating the actual stroke difference;
The said stroke difference calibration means makes the actual stroke difference in that case zero when the said actual stroke difference continues the same value over predetermined time, The any one of Claims 1-4 characterized by the above-mentioned. A vehicle equipped with a damper having a variable damping force according to one item.

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