JPH082234A - Body inclination calculator - Google Patents

Abstract

PURPOSE:To find a body inclination more accurately by calculating this inclination based on the detected vertical rigidity and acceleration. CONSTITUTION:An electronic controller 100 of a hydraulic active suspension detects longitudinal acceleration and lateral acceleration acting on a car body through a longitudinal G sensor 122 and a lateral G sensor 124, while it detects each wheel air pressure of respective wheels via revolving speed, thereby finding both pitch and roll angles on the basis of these detected results. In consequence, even if wheel air pressure of each wheel is varied and vertical rigidity of the wheel is changed, a variation in the vertical rigidity of this wheel is reflected to the operation of these pitch and roll angles, so that those of actual roll and pitch angles are accurately findable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body inclination angle calculating device for calculating a vehicle body inclination angle.

[0002]

2. Description of the Related Art Various accelerations such as a lateral acceleration (lateral acceleration) and a longitudinal acceleration (longitudinal acceleration) are applied to a vehicle body of a running vehicle, and these accelerations affect the vehicle body. Tilts laterally or longitudinally. The former inclination is expressed as a roll and the latter inclination is expressed as a pitch, which changes the posture of the vehicle body. Therefore, various techniques have been proposed in order to suppress such a posture change of the vehicle body.

For example, in Japanese Patent Laid-Open No. 3-70614, a roll angle and a pitch angle when a vehicle body rolls or pitches are calculated based on lateral acceleration and longitudinal acceleration, and a fluid pressure actuator for suspending the vehicle body is determined by the inclination angle of the vehicle body. Drive control technology has been proposed on the side of reduction. More specifically, the reduction of the roll will be explained. When the vehicle turns, a lateral acceleration is generated by the centrifugal force, and the vehicle body tries to roll in the direction of the centrifugal force. Therefore, the lateral acceleration applied to the vehicle body is detected,
Estimate and calculate the roll angle of the vehicle body according to the detection result,
The fluid is discharged from the fluid pressure actuator on the inner ring side by a control amount according to the calculation result, and the internal pressure is reduced to lower the vehicle height. On the other hand, on the outer wheel side, a fluid is supplied to the fluid pressure actuator by a control amount according to the above-described roll angle estimation calculation to increase the internal pressure and increase the vehicle height. By controlling each actuator in this way, the posture of the vehicle body is brought close to horizontal.

[0004]

In the above-mentioned conventional technique, if the estimated vehicle body inclination angle such as the calculated roll angle and pitch angle substantially matches the actual vehicle body inclination angle, good attitude control performance is obtained. Can be demonstrated. However, factors affecting the inclination of the vehicle body suspended by the fluid pressure actuator or the like include various factors other than acceleration, such as the spring constant as a vertical spring exerted by the wheel (that is, the vertical rigidity of the wheel). Etc. Therefore, when these factors such as the elastic constant of the rubber of the tire forming the wheel and the air pressure inside the tire are changed, the estimated vehicle body inclination angle and the actual vehicle body inclination angle are different, and the control performance is deteriorated or deteriorated.

The above-mentioned problems are not peculiar to suspension control, and are controls relating to the running behavior of the vehicle, such as damping force switching control, roll rigidity distribution ratio control, four-wheel steering control, four-wheel drive control. As long as the device to be controlled in the brake control, the engine control, etc. is controlled according to the vehicle body inclination angle, it appears to some extent regardless of the type.

The present invention has been made to solve the above problems, and an object thereof is to more accurately obtain a vehicle body inclination angle such as a roll angle or a pitch angle.

[0007]

In order to achieve the above object, the means adopted by the vehicle body inclination angle calculating device according to claim 1 is a device for calculating a vehicle body inclination angle of a vehicle, which acts on the vehicle body. An acceleration detecting means for detecting acceleration, a wheel vertical rigidity detecting means for detecting vertical rigidity of the wheel of the vehicle, and an inclination angle calculating means for calculating a vehicle body inclination angle based on the detected vertical rigidity and acceleration are provided. This is the gist.

In this case, in the vehicle body inclination angle calculating device according to the second aspect, the acceleration detecting means detects the lateral acceleration acting on the vehicle body, and the inclination angle calculating means comprises:
The roll angle of the vehicle body is calculated based on the lateral acceleration and the vertical rigidity.

Further, in the vehicle body inclination angle calculating device according to the present invention, the acceleration detecting means detects the longitudinal acceleration acting on the vehicle body, and the inclination angle calculating means comprises the longitudinal acceleration and the vertical rigidity. The pitch angle of the vehicle body is calculated based on

Further, in the vehicle body inclination angle calculating device according to the present invention, the wheel vertical rigidity detecting means detects the air pressure of the wheel of the vehicle.

[0011]

In the vehicle body inclination angle calculating device having the above structure, when acceleration acts on the vehicle body, the acceleration detecting means detects the acceleration, and on the other hand, the wheel vertical stiffness detecting means detects the vertical direction of the vehicle wheel. Detect rigidity. Then, the vehicle body inclination angle is calculated by the inclination angle calculation means based on the detected vertical rigidity and acceleration. Therefore, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the calculation of the vehicle body inclination angle.

In this case, the vehicle body inclination angle calculating device detects the lateral acceleration acting on the vehicle body and calculates the vehicle body inclination angle as the vehicle body inclination angle. Therefore, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the calculation of the roll angle of the vehicle body.

Further, in the vehicle body inclination angle calculating device according to the third aspect, the longitudinal acceleration acting on the vehicle body is detected, and the vehicle body pitch angle is calculated as the vehicle body inclination angle. Therefore, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the calculation of the pitch angle of the vehicle body.

Further, in the vehicle body inclination angle calculating device according to the present invention, since the air pressure of the wheel of the vehicle is detected, even if the air pressure of the wheel fluctuates and the vertical rigidity of the wheel changes, the vertical rigidity of the wheel changes. The change is reflected in the calculation of the vehicle body inclination angle.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a vehicle body inclination angle calculating device according to the present invention will be described with reference to the drawings, taking a case where the device is mounted and applied to a fluid pressure type active suspension as an example. FIG. 1 is a schematic configuration diagram showing a fluid circuit of a fluid pressure type active suspension 10 to which a vehicle body inclination angle calculating device of an embodiment is applied. In addition, in FIG. 1,
Although only a schematic configuration diagram of one wheel is shown as a representative, other wheels have the same configuration.

As shown in the figure, the fluid pressure type active suspension 10 is provided with a reservoir 11 for storing oil as a working fluid, and one end of a connection passage 12 and one end of a working fluid discharge passage 14 are connected to the reservoir 11. ing. The other end of the connection passage 12 is connected to the suction side of a pump 18 driven by the engine 16. Pump 18 is a variable displacement pump in the illustrated embodiment,
One end of the working fluid supply passage 20 is connected to the discharge side. The other end of the working fluid supply passage 20 and the other end of the working fluid discharge passage 14 respectively communicate with the P port and the R port of a pilot operated three-port three-position switching type switching control valve 24 that constitutes the pressure control valve 22. It is connected. In the middle of the working fluid discharge passage 14 of each wheel, the communication connection portion 1 where the working fluid discharge passages of the other wheels merge.
A check valve 15 is provided closer to the pressure control valve 22 than 4a. Therefore, in the working fluid discharge passage 14,
This check valve 15 allows the pressure control valve 22 to move from the reservoir 1
Only the flow of working fluid towards 1 is allowed.

The pressure control valve 22 includes a switching control valve 24, a branch passage 26 branching from the working fluid supply passage 20 to reach the reservoir 11, a fixed throttle 28 and a branch passage 26 provided in the middle of the branch passage 26. And a variable throttle 30 that changes the effective passage cross-sectional area thereof by a built-in solenoid. The variable throttle 30 of the pressure control valve 22 is connected to an electronic control unit 100 described later, and the electronic control unit 10 is connected.
When the current is controlled to the solenoid by 0, it cooperates with the fixed throttle 28 to change the pressure Pp in the branch passage 26 between the fixed throttle 28 and the variable throttle 30. One end of the connection passage 32 is connected to the A port of the switching control valve 24.
The other end of the connection passage 32 is communicatively connected to a working fluid chamber 38 of an actuator 36 provided corresponding to the wheel. As shown in the figure, the actuator 36 is a kind of cylinder piston device, is arranged between the suspension member supporting the wheels Wh and the vehicle body to suspend the vehicle body, and the working fluid is supplied to and discharged from the working fluid chamber 38. As a result, the vehicle height of the corresponding portion is increased or decreased as described below.

The switching control valve 24 of the pressure control valve 22 controls the above-mentioned pressure Pp via the fixed throttle 28 and the variable throttle 30.
A spool valve that takes in the pressure Pa in the connection passage 32 as a pilot pressure via the throttle 34 of the passage, switches the direction of the oil flow by the balance between the pressure Pp and the pressure Pa, and supplies and discharges the oil to and from the actuator 36. Do.

Generally, the variable diaphragm 30 is an electronic control unit 100.
The solenoid is controlled to change the effective passage area of the branch passage 26. If the pressure Pp in the branch passage 26 and the pressure Pa in the connection passage 32 are equal when the effective passage cross-sectional area of the branch passage 26 has a certain value, the switching control valve 2
4 has a switching position 24b that shuts off communication with all ports.

When the variable throttle 30 is controlled by the electronic control unit 100 so that the pressure Pp becomes low, the pressure P
Since a becomes higher than the pressure Pp, the switching control valve 24 switches to the switching position 24c that connects and connects the port R and the port A, and keeps this position until the pressure Pa and the pressure Pp become equal. Therefore, the working fluid chamber 3 of the actuator 36
Oil is discharged from No. 8, and the vehicle height is lowered by the actuator 36. On the other hand, when the variable throttle 30 is controlled to increase the pressure Pp, the pressure Pa becomes lower than the pressure Pp, so that the switching control valve 24 switches to the switching position 24a that connects the port P and the port A to each other, and the pressure is reduced. This position is maintained until Pa and the pressure Pp become equal. Therefore, oil is supplied from the pump 18 to the working fluid chamber 38 of the actuator 36, and the vehicle height is increased by the actuator 36.

A gas-liquid spring device 42 is connected to the working fluid chamber 38 by a passage 40, and a throttle 44 is provided in the middle of the passage 40. The gas-liquid spring device 42 acts as a suspension spring or an auxiliary suspension spring, and the throttle 44 generates a damping force. Further, the actuator 36 is provided with a pressure sensor 37 that detects the oil pressure in the working fluid chamber 38. In addition, a vehicle height sensor 118 that detects the vehicle height of the vehicle body is provided between the suspension member that supports the wheels Wh and the vehicle body.

A pilot-operated shutoff valve 46 is provided in the middle of the connection passage 32.
6 takes in pilot pressure Pc controlled by a pilot pressure control device 48 described later. And shutoff valve 4
No. 6 opens when the pilot pressure Pc exceeds a valve opening predetermined value, and closes when the pilot pressure falls below a valve closing predetermined value. A pilot pressure control device 48 is provided in a connection passage 50 that connects the working fluid supply passage 20 and the reservoir 11 to each other, and the pilot pressure control device 48 includes:
Fixed throttle 52 and connection passage 50 provided in the middle of the passage
And a variable restrictor 54 that changes the effective passage cross-sectional area of the device by a built-in solenoid. The variable throttle 54 is connected to an electronic control unit 100, which will be described later, and when the electronic control unit 100 controls the current to the solenoid, it cooperates with the fixed throttle 52 to connect the fixed throttle 52 and the variable throttle 54. The pressure Pc in the connecting passage 50 is changed. Therefore, the pilot pressure control device 48 changes the pilot pressure Pc by the variable throttle 54 and supplies it to the shutoff valve 46.
Opens or closes the connection passage 32 according to the pilot pressure Pc.

Further, in the middle of the working fluid supply passage 20,
A check valve 58 is provided which allows only the flow of working fluid from the filter 56 and pump 18 towards the pressure control valve 22. An accumulator 60 is connected to the working fluid supply passage 20 downstream of the check valve 58.

The pressure control valve 22, the connection passage 32,
The diaphragm 44, the actuator 36, the pressure sensor 37, the gas-liquid spring device 42, etc. are provided corresponding to each wheel. In addition, these constituent members of each wheel (right front wheel, left front wheel, right rear wheel, and left rear wheel) are respectively denoted by FR, FL, RR, RL.
Is added, for example, the pressure control valve 22 is 22F
It will be referred to as R, 22FL, 22RR, and 22RL.

Next, the electrical construction of the fluid pressure type active suspension 10 will be described. As shown in FIG. 2, the pilot pressure control device 48 and the pressure control valve 22FR
22 to 22RL are respectively connected to the electronic control unit 100, and the pilot pressure control unit 48 and each pressure control valve 2 are connected.
The variable diaphragm 54 and the variable diaphragm 30 included in 2FR to 22RL are controlled by the electronic control unit 100. The electronic control unit 100 includes a microcomputer 102 mainly including a central processing unit (CPU) 104.
As is well known, the microcomputer 102 is a CP.
U104, read only memory (ROM) 106,
It has a random access memory (RAM) 108, an input port device 110, and an output port device 112, which are connected to each other by a bidirectional common bus 114.

The input port device 110 includes various switches and sensors such as an ignition switch (IGS).
W) 116 and vehicle height sensors 118FL and 118F for each wheel
R, 118RL, 118RR and pressure sensor 37 for each wheel
FL, 37FR, 37RL, 37RR, a vehicle speed sensor 120 that detects a vehicle speed, a front-rear G (acceleration) sensor 122 that detects acceleration in the front-rear direction of the vehicle body, and a lateral G sensor 124 that detects acceleration in the lateral direction of the vehicle body. , A steering angle sensor 126 for detecting the steering angle of the steering wheel, a vehicle height setting switch 128 for setting the vehicle height control mode to either a high mode or a low mode, and wheel speeds for detecting the rotational speed of each wheel. Sensors 140FL, 140FR, 140RL,
140RR is connected.

Then, the electronic control unit 100 uses various signals from these switches and sensors, specifically, a signal indicating whether or not the ignition switch is in the ON state, each wheel (front left wheel, front right wheel, rear left wheel). A signal indicating the vehicle height Xi (i = 1,2,3,4) corresponding to the wheels and the right rear wheel, and the oil pressure Pi (i = 1,2) in the working fluid chamber 38 of the actuator 36 of each wheel. , 3, 4), a signal indicating the vehicle speed V, a signal indicating the longitudinal acceleration Gx of the vehicle body, a signal indicating the lateral acceleration Gy of the vehicle body, a signal indicating the steering angle θ of the steering wheel, and the vehicle height control mode is the high mode. Signal indicating whether the vehicle is in the low mode or the rotational speed of each wheel Vwi (i = 1, 2, 3,
4) Input the signal, etc. Incidentally, the values 1, 2, 3, 4 which can be taken by the subscript i in the vehicle height Xi, the oil pressure Pi, the rotational speed Vwi, etc. are the vehicle heights such as the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively. , And the subscript i is used for this meaning in the following description.

The input port device 110 appropriately processes the above-mentioned input signal and outputs the processed signal to the CPU and the RAM 108 according to an instruction of the CPU 104 based on a program stored in the ROM 106. The ROM 106 stores the control flow shown in FIGS. 3 to 6 and the control flow not shown, as well as the maps shown in FIGS. 7 to 15, and the CPU processes signals based on each control flow. It is like this. The output port device 112 follows the instruction of the CPU 104 and drives the drive circuit 13
The control signal is output to the variable throttle 54 of the pilot pressure control device 48 via 0, and the control signal is output to the variable throttle 30 of the pressure control valves 22FR to 22RL via the drive circuits 132 to 138.

Next, regarding the suspension control performed by the fluid pressure type active suspension 10 of this embodiment,
This will be described with reference to the flowcharts of FIG. The suspension control shown is based on the ignition switch 11
It is started by turning on the ignition switch 6, and is ended shortly after the ignition switch is turned off.

In the first step S10, a control signal is output to the solenoid of the variable throttle 54 of the pilot pressure control device 48 to gradually reduce the effective passage sectional area of the variable throttle 54, thereby gradually increasing the pilot pressure Pp. To do. In this process, the shutoff valve 46 is opened, the pressure of the working fluid in the working fluid supply passage 20 reaches a predetermined pressure, and the shutoff valve 46 is fully opened, that is, the supply and discharge of oil to the actuator 36. In the enabled state, the process proceeds to the next step S20.

In step S20, the ignition switch 116, the vehicle height sensor 118 for each wheel,
In addition to the pressure sensor 37, the vehicle speed sensor 120, the longitudinal G sensor 122, the lateral G sensor 124, the steering angle sensor 126, the vehicle height setting switch 128, the wheel speed sensor 140, and the like are scanned, and corresponding signals are output from the respective switches and sensors. After reading, the process proceeds to step S30 and thereafter. That is, in this step S20, a signal indicating whether or not the ignition switch 116 is in the ON state, a signal indicating the vehicle height Xi of each wheel, and a signal indicating the oil pressure Pi in the working fluid chamber 38 of the actuator 36 of each wheel. , A signal indicating the vehicle speed V, a signal indicating the longitudinal acceleration Gx of the vehicle body, a signal indicating the lateral acceleration Gy, a signal indicating the steering angle θ of the steering wheel, and a signal indicating whether the set mode is the high mode or the low mode. , Various signals such as a signal indicating the rotation speed Vwi of each wheel are read.

In step S25 following step S20, each rotational speed Vwi of each wheel Whi (i = 1, 2, 3, 4) is calculated based on the signal read from each wheel speed sensor 140. In this case, when the wheel speed sensor 140 is of a type that outputs a pulse signal at each predetermined rotation angle of the wheel Whi, another processing routine (not shown) activated by using this pulse signal as an interrupt source The rotational speed Vwi can be calculated by measuring the time interval of the input pulse signal and using it. In addition, the wheel speed sensor 140
The rotation speed Vwi may be calculated based on the number of pulses input from. Of course, if the wheel speed sensor 140 is a type capable of directly outputting the instantaneous value of the wheel speed, the signal may be used as it is as the rotation speed Vwi.

In the following step S30, bandpass filter processing is performed on the rotation speed Vwi obtained in step S25 to extract only the components in the band 1 to 3 Hz. This bandpass filtering process is performed at the rotational speed V
This is a process of extracting only the component in the band 1 to 3 Hz with respect to the change of wi, giving a predetermined weighting to the rotation speed Vwi, taking an arithmetic mean with the calculation results up to that time, and calculating the maximum value and the minimum value thereof. A process of calculating the deviation as the variation amount ΔV may be considered. In addition to this, a discrete Fourier transform may be performed by software to extract the signal intensity of 1 to 3 Hz.

1 to 3 by bandpass filtering
The reason why only the Hz component is extracted is to remove the influence of the DC component and noise and to extract only the vibration near the sprung resonance frequency. The band of the filter processing may be adjusted to an optimum range depending on the sprung resonance frequency of the vehicle to be applied, but the sprung resonance frequency itself may not necessarily be included as long as it is in the vicinity of the sprung resonance frequency.

In the following step S35, the wheel air pressure Pwi (i = 1, 2, 3, 4) for each wheel Whi is calculated. For the wheel air pressure Pwi, the unsprung resonance frequency is detected by performing bandpass filter processing in the unsprung resonance frequency band of 10 to 100 Hz with respect to the change in the rotation speed Vwi obtained in step S25. Based on the lower resonance frequency, it is determined from a map (for example, FIG. 7) showing the relationship between the unsprung resonance frequency and the wheel air pressure Pwi stored in the ROM 106 of the electronic control unit 100 in advance. Here, from the rotation speed Vwi to the wheel air pressure Pw
i is required for the following reasons.

Wheels of a running vehicle vibrate up and down and back and forth due to minute irregularities on the road surface. The vibration component of the wheel is included in the detection signal of the wheel speed sensor, and when the detection signal is subjected to frequency analysis, two unsprung resonance frequencies that resonate with the vibrations of the upper, lower, front and rear of the wheel appear as peaks. The two unsprung resonance frequencies are determined by the wheel air pressure Pwi.
Changes with the spring constant K of the rubber part of the wheel, which is determined by the magnitude of Therefore, one of the two unsprung resonance frequencies is extracted from the rotation speed Vwi to obtain the spring constant K of the wheel rubber portion, and the wheel air pressure Pwi can be calculated from the spring constant K. For this principle, for example,
The details are described in JP-A-5-213018.

In this embodiment, the wheel air pressure Pwi is calculated from the map showing the relationship between the unsprung resonance frequency and the wheel air pressure Pwi.
However, the wheel air pressure Pwi may be calculated by obtaining the spring constant K from a map showing the relationship between the unsprung resonance frequency and the spring constant K of the wheel rubber portion, and multiplying the obtained spring constant K by a predetermined value α. Good. Here, the predetermined value α is a conversion coefficient for obtaining the wheel air pressure Pwi that is linearly determined with respect to the spring constant K, and is determined by the material forming the wheel, the shape of the wheel, and the like. Further, in the present embodiment, the wheel air pressure Pwi is obtained based on the rotation speed Vwi, but a configuration including a sensor for directly detecting the wheel air pressure Pwi is also suitable.

Step S following the calculation of the wheel air pressure Pwi
In 40, the roll rigidity kr and the pitch rigidity kp of the vehicle are calculated based on the wheel air pressure Pwi using the maps corresponding to the graphs shown in FIGS. 8 and 9, and then the process proceeds to step S45. As shown in these graphs,
Wheel air pressure Pwi, roll rigidity kr and pitch rigidity k
p is the wheel air pressure Pwi over a predetermined range (for example, ± 20% of Pwo) centered on the standard air pressure Pwo.
Has a proportional relationship in which the respective rigidity decreases as the value decreases. In other ranges, the lower limit value or the upper limit value is set. This is because if the wheel air pressure Pwi is within this predetermined range, even if the control according to the roll angle and the pitch angle described below is performed, the wheel air pressure Pwi is abnormal, so that the roll and the pitch cannot be further suppressed. This is because it is not realistic and the discharge capacity of the pump 18 is effectively used for other control. The standard air pressure Pwo is a wheel air pressure set as a standard value in a vehicle in which the fluid pressure type active suspension 10 of this embodiment is mounted.

In this case, the initial value kro of the roll rigidity and the initial value kpo of the pitch rigidity when the wheel air pressure Pwi of each wheel is all the standard air pressure Pwo described above are used as the wheel air pressure Pw.
It is also possible to make a correction by i and calculate the roll rigidity kr or the pitch rigidity kp at that time. Further, the standardized air pressure Pwoi obtained by dividing the calculated wheel air pressure Pwi of each wheel by the standard air pressure Pwo, the relative wheel air pressure of the calculated wheel air pressure Pwi of each wheel, or the like may be used.

In step S45 subsequent to step S40, the roll angle φ0 and pitch are calculated in accordance with the following equations by using the roll rigidity kr and pitch rigidity kp obtained and the longitudinal acceleration Gx and lateral acceleration Gy of the vehicle body read in step S20. The angle λ0 is calculated, and then the process proceeds to step S50.

Ir · φ2 + Cr · φ1 + (kr-Ms · Hr · g) · φ0 = Ms · Gy · Hr ... Equation 1 Ip · λ2 + Cp · λ1 + (kp-Ms · Hp · g) · λ0 = Ms -Gx-Hp ... Formula 2

In the above formula 1, Ir is the roll moment, φ2 is the roll angular acceleration, φ1 is the roll angular velocity, Cr is the roll equivalent damping coefficient (constant), and Ms is the sprung mass of the vehicle. (Constant), Hr is the distance between the center of gravity of the roll shafts (constant), and g is the acceleration of gravity (constant). On the other hand, in Equation 2, Ip is the pitch moment, λ2 is the pitch angular acceleration, λ1 is the pitch angular velocity, Cp is the pitch equivalent damping coefficient (constant), and Ms is the sprung mass of the vehicle (constant). And
Hp is the distance between the center of gravity of the pitch axis (constant), and g is the acceleration of gravity (constant). The roll angle φ 0 has a second-order differential relationship with the roll angular acceleration φ 2 and the roll angular velocity φ
1 is related to the first derivative. Similarly, the pitch angle λ0
Has a second derivative relationship with the pitch angular acceleration λ2 and has a first derivative relationship with the pitch angular velocity λ1. For this reason,
The above formulas 1 and 2 are the roll angle φ 0 and the pitch angle λ 0 2
It is the following differential equation, and roll stiffness kr, pitch stiffness kp, longitudinal acceleration Gx, lateral acceleration Gy, and each of the above constants are substituted into the corresponding equations to solve the quadratic differential equation. The pitch angle λ0 is calculated.

In step S50 subsequent to step S45, in order to control the attitude of the vehicle body and the ride comfort of the vehicle, active calculation is performed based on the various signals read in step S20, and each pressure control valve controls. Target pressure Pui in actuator 36
Is calculated. Then, after that, step S shown in FIG.
Proceed to 60. The active calculation for calculating the target pressure Pui will be described later in detail with reference to FIGS. 5, 6, and 10 to 15.

In step S60, the target current Ii to be supplied to the variable throttle 30 of each pressure control valve 22 is calculated based on the actively calculated target pressure Pui, and then the process proceeds to step S70.

In step S70, step S6
The target current Ii calculated at 0 is applied to each pressure control valve 22.
To the solenoid of the variable throttle 30 to drive each pressure control valve 22, thereby controlling the pressure in each actuator 36 to the corrected target pressure Pai. Then, after that, the process proceeds to step S80.

In step S80, it is determined whether or not the ignition switch 116 has been switched from ON to OFF, and the ignition switch 116 is turned ON to OFF.
When it is determined that the mode has not been switched to F, the process returns to step S20 (see FIG. 3) and the above-described processing is repeated. On the other hand, when it is determined that the ignition switch is switched from ON to OFF, the process proceeds to step S90.

In step S90, a control signal is output to the solenoid of the variable throttle 54 in the pilot pressure control device 48 to gradually increase the effective passage sectional area of the variable throttle in the connecting passage 50. In this process, the pilot pressure Pc of the shutoff valve 46 gradually decreases due to the gradual increase of the oil flow rate, and the shutoff valve 46 is closed, whereby the supply / discharge of the working fluid to / from the actuator 36 is completed.

Next, referring to the flowcharts of FIGS. 5 and 6 and the graphs of FIGS. 10 to 15, step S3
An example of the active calculation performed at 0 will be described.

As shown in FIG. 5, in step S100 following step S45, the heave target value Rxh, the pitch target value Rxp, and the roll target value Rxr based on the target posture of the vehicle body are set in FIGS. 10, 11, and 12, respectively. The calculation is performed based on the map corresponding to the graph shown in (1), and then the process proceeds to step S110. The solid line in FIG. 10 shows the pattern when the vehicle height control mode set by the vehicle height setting switch 128 is the normal mode, and the dotted line shows the pattern when it is the high mode.

In step S110, step S
Based on the vehicle heights X1 to X4 at positions corresponding to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel read in 20, heave (Xxh), pitch (Xxp), roll (Xxr), The displacement mode conversion for warp (Xxw) is calculated, and then the process proceeds to step S120.

Xxh = (X1 + X2) + (X3 + X4) Equation 3 Xxp =-(X1 + X2) + (X3 + X4) Equation 4 Xxr = (X1-X2) + (X3-X4) Equation 5 Xxw = (X1-X2)-(X3-X4) ... Equation 6

In step S120, the displacement mode deviation is calculated according to the following equation, and then the process proceeds to step S130.

Exh = Rxh-Xxh Formula 7 Exp = Rxp-Xxp Formula 8 Exr = Rxr-Xxr Formula 9 Exw = Rxw-Xxw Formula 10

In this case, the warp target value Rxw may be 0, or it may be Xxw calculated in step S110 immediately after the activation of the active suspension or the average value of Xxw calculated in the past several cycles. Good. If the absolute value of Exw (| Exw |) ≤W1 (a positive constant), Exw = 0.

In step S130, PID compensation calculation of displacement feedback control is performed according to the following formula, and then the process proceeds to step S140.

Cxh = Kpxh * Exh + Kixh * Ixh (n) + Kdxh {Exh (n) -Exh (n-n1)} Equation 11 Cxp = Kpxp * Exp + Kixp * Ixp (n) + Kdxp {Exp (n) -Exp (n) -n1)} Equation 12 Cxr = Kpxr * Exr + Kixr * Ixr (n) + Kdxr {Exr (n) -Exr (n-n1)} Equation 13 Cxw = Kpxw * Exw + Kixw * Ixw (n) + Kdxw {Exw (n) -Exw (n-n1)} Equation 14

In the above equations, Ej (n) (j = x
h, xp, xr, xw) is the current Ej, and Ej (n-n1) is n1
It is Ej before the cycle. Also, Ij (n) and Ij (n-1)
Let Ij be the current and one cycle before, respectively, I
j (n) can be described as follows with Tx as a time constant.

Ij (n) = Ej (n) + Tx Ij (n-1) Equation 15

In this case, the absolute value of Ij (| Ij |) is
| Ij | ≦ Ijmax, where Ijmax is a predetermined value. Furthermore, the coefficients Kpj, Kdj and Kij (j = xh, xp, xr, xw)
Are proportional constants, differential constants and integral constants, respectively.

In step S140, the inverse transformation of the displacement mode is calculated according to the following equation, and then the process proceeds to step S150 shown in FIG.

Px1 = 1/4 · Kx1 (Cxh−Cxp + Cxr + Cxw) Equation 16 Px2 = 1/4 · Kx2 (Cxh−Cxp−Cxr−Cxw) Equation 17 Px3 = 1/4 · Kx3 (Cxh + Cxr + Cxw) ... Formula 18 Px4 = 1/4 · Kx4 (Cxh + Cxp−Cxr + Cxw) Formula 19

It should be noted that KX1, KX2, K in the above equations
X3 and KX4 are proportional constants.

In step S150, the front-rear direction and the lateral direction of the vehicle are shown in FIGS. 13 and 14, respectively.
Based on the map corresponding to the graph shown in
gx and Pgy are calculated, and then the process proceeds to step S160.

In step S160, G for pitch (Cgp) and roll (Cgr) is calculated according to the following equation.
The PD compensation calculation of the feedback control is performed, and then the process proceeds to step S170.

Cgp = Kpgp.Pgx + Kdgp {Pgx (n) -Pgx (n-n1)} Equation 20 Cgr = Kpgr.Pgy + Kdgr {Pgy (n) -Pgy (n-n1)} Equation 21

In the PD compensation calculation of the G feedback control in step S160, step S45
Proportional constants Kpgp and Kpgr determined as follows based on the pitch angle λ 0 and roll angle φ 0 calculated in
The differential constants Kdgp and Kdgr are used. Step S45
If the pitch angle λ0 and the roll angle φ0 calculated in step 3 are large, there is a large pitch or roll in the vehicle body. Therefore, the larger the calculated pitch angle λ 0 and roll angle φ 0, the more effective the formula 2
The proportional constants Kpgp and Kpgr at 0 and 21 are set as large values. If the current calculated pitch angle and roll angle are λ0n and φ0n and the calculated pitch angle and roll angle in the suspension control one cycle before are λ0n-1 and φ0n-1, the rate of change is large The degree of change in pitch and roll that has occurred is also large. Therefore, the larger the change rates of the calculated pitch angle and roll angle, the more effectively and quickly the pitch and roll are suppressed, so that the differential constants Kdgp and Kdg in Equations 20 and 21 are reduced.
r is defined as a large value.

In the above equations, Pgx (n) and Pgy (n) are the current Pgx and Pgy, respectively, and Pgx
(n-n1) and Pgy (n-n1) are Pgx before n1 cycles, respectively.
And Pgy.

In step S170, the steering angle velocity θ'is calculated according to the following equation, where θn is the current steering angle and θn-1 is the steering angle read in step S20 in the suspension control one cycle before. Then, based on the calculated steering angular velocity θ ′, the vehicle speed V read in step S20, and the map corresponding to the graph shown in FIG. 15, the change rate Gypr of the predicted lateral G is calculated, and then the process proceeds to step S180.

Θ ′ = θn−θn−1 Equation 22

In step S180, the inverse conversion operation in the G mode is performed according to the following equation, and then the process proceeds to step S190. That is, this step S180
Then, the control amount of the entire vehicle, which has been calculated in step S160 in order to suppress the roll and the pitch, is distributed and calculated for each wheel.

Pg1 = Kg1 / 4 · (−Cgp + K2f · Cgr + K1f · Gypr) Equation 23 Pg2 = Kg2 / 4 · (−Cgp−K2f · Cgr−K1f · Gypr) Equation 24 Pg3 = Kg3 / 4 · (Cgp + K2r ·) Cgr + K1r · Gypr) Equation 25 Pg4 = Kg4 / 4 · (Cgp−K2r · Cgr−K1r · Gypr) Equation 26

In the inverse conversion calculation of the G mode in step S180, the proportional constant Kgi (i = 1,2,3, i) determined as follows based on the wheel air pressure Pwi for each wheel calculated in step S35. 4) is used. That is, since the wheel air pressure Pwi of each wheel is not always uniform, the spring constant of each wheel that affects the roll rigidity and pitch rigidity of each wheel also differs from one wheel to another. Therefore, the wheel air pressure Pwi of each wheel itself or its standardization has been completed. Air pressure Pw
Inverse calculation of G mode is performed in consideration of oi or relative wheel air pressure of each wheel. Note that K1f in the above equations
And K1r, K2f, and K2r are constants as distribution gains between the front and rear wheels.

When the wheel air pressure Pwi decreases, the spring constant of the wheel also decreases. Therefore, the drive amount of the actuator 36 of the wheel corresponding to the low wheel air pressure Pwi (pressure control valve 2
The proportional constant Kgi is set so as to relatively increase the control amount of 2) with respect to the other wheels having high wheel air pressure Pwi, and is used in each of the above equations.

Step S190 following step S180
, The standard pressure Pbi in the working fluid chamber 38 of each actuator 36 stored in the ROM (the pressure in the working fluid chamber 38 when the vehicle is stopped) and the results calculated in step S140 and step S180. Based on the above, the control target pressure Pui of each pressure control valve 22 is calculated according to the following equation, and then the process proceeds to step S60 of FIG.

Pui = Pxi + Pgi + Pbi (i = 1, 2, 3, 4) Equation 27

As described above, in the fluid pressure type active suspension 10 equipped with the vehicle body inclination angle calculating device of the present embodiment, the longitudinal G sensor 122 and the lateral G sensor 12 are provided.
4, the longitudinal acceleration and the lateral acceleration acting on the vehicle body are detected (step S20), the wheel air pressure Pwi of each wheel Wh is detected via the rotation speed Vwi (step S35), and the pitch angle λ0 is detected based on these detection results. And the roll angle φ0 are obtained (step S45). As a result,
According to the vehicle body inclination angle calculating device of this embodiment, even if the wheel air pressure Pwi of each wheel fluctuates and the vertical rigidity (roll rigidity, pitch rigidity) of the wheel changes, the vertical rigidity of the wheel is changed. Since it is reflected in the calculation of the angle φ 0 and the pitch angle λ 0, the actual roll angle and pitch angle can be accurately obtained.

Further, in this embodiment, since the wheel air pressure Pwi is obtained based on the rotation speed Vwi, it is not necessary to provide a sensor for measuring the air pressure on each tire, and the cost can be reduced. In addition, the wheel speed sensor 14 for each wheel
Since 0 can be shared as a sensor for controlling the braking force, the number of parts, the number of assembling steps, and the cost can be reduced, and the configuration can be simplified to improve the reliability. Furthermore, since the arithmetic processing of the wheel air pressure Pwi is realized by software, the front and rear G sensor 1
It is possible to accurately calculate the roll angle and the pitch angle of an existing vehicle equipped with the No. 22, the lateral G sensor 124, and the wheel speed sensor 140 by simply modifying the software. It can also contribute to effective use of resources.

Further, according to the fluid pressure type active suspension 10 of the present embodiment, the driving amount of the actuator 36 of each wheel (control amount of the pressure control valve 22) is obtained according to the roll angle and the pitch angle which are obtained with high accuracy. Therefore, the effect of suppressing the roll and pitch of the vehicle body can be enhanced. Moreover,
When distributing the control amount of the entire vehicle for suppressing the roll and the pitch to each wheel, a low wheel air pressure P
Since the drive amount of the wheel actuator 36 (control amount of the pressure control valve 22) corresponding to wi is increased relatively to other wheels having high wheel air pressure Pwi, the fluid pressure type active suspension of the present embodiment. According to 10,
The effect of suppressing the roll and pitch of the vehicle body can be further enhanced. Further, since the calculation processing of the wheel air pressure Pwi, the roll angle and the pitch angle is realized by software,
The control performance of an existing vehicle that performs attitude control and the like by the actuators 36 of the respective wheels can be enhanced by improving the effect of suppressing rolls and pitches only by making a simple modification such as changing software.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and can be implemented in various modes without departing from the scope of the present invention. Of course.

For example, in the above-described embodiment, since the air pressure of the wheel corresponds to the vertical rigidity of the wheel almost one-to-one, it is possible to replace the detection of the vertical rigidity of the wheel by detecting the air pressure of the wheel. -ing Therefore, other methods and configurations can be adopted. Specifically, it is configured to detect the surface temperature of the tire forming the wheel, estimate the elastic constant of the rubber of the tire from the result, and obtain the vertical rigidity of the wheel based on the estimated elastic constant of the rubber of the tire. You can also That is, in this case, the detection of the surface temperature of the tire and the estimation of the rubber elastic constant are used as an alternative to the detection of the vertical rigidity of the wheel. Further, the vertical rigidity of the wheel may be estimated based on the air pressure of the wheel and the elastic constant of the rubber of the tire.

Further, the active calculation, that is, the calculation of the target pressure Pui in the working fluid chamber 38 of each actuator 36 is configured to be performed in a specific manner based on the detection results of various sensors. The aspect is an arbitrary aspect as long as it is a calculation that can favorably control the posture of the vehicle body and the riding comfort of the vehicle by controlling the target pressure in the working fluid chamber 38 of each actuator 36 according to the traveling state of the vehicle. Can be taken.

Further, in the present embodiment, the control valve is configured as the pressure control valve 22 for directly switching the pressure in the connection passage 32 and the branch passage 26 to perform switching. However, this control valve is provided in the working fluid chamber 38. Needless to say, it may be configured as a flow rate control valve in which the pressure is detected by a pressure sensor and is electrically switched by a solenoid or the like based on the detected value.

Further, in the above-described embodiment, the standard pressure Pbi in the working fluid chamber 38 of each actuator 36 used for the calculation of step S190 is a constant, but this pressure has passed a predetermined time after the start of control. The pressure Pi in each working fluid chamber 38 detected by the pressure sensor at the time point,
It may be an average value of the pressures Pi detected by the pressure sensor until a predetermined time elapses after the control is started.

In addition, in the present embodiment, the fluid pressure type active suspension 10 equipped with the vehicle body inclination angle calculating device is mounted.
However, the vehicle body tilt angle calculation device of the present invention can be applied to any vehicle that controls various traveling target devices according to the roll angle and the pitch angle of the vehicle body to control the traveling behavior of the vehicle. Of course. For example, a damping force switching control, a roll rigidity distribution ratio control, a four-wheel steering control, a four-wheel drive control, a brake control, an engine control, etc., which are examples of controls related to the running behavior of a vehicle, are set to a vehicle inclination angle. Any type of control can be applied. Then, by applying the vehicle body inclination angle calculating device of the present invention to these controls, it is not necessary to control the control target device according to these inclination angles that are significantly different from the actual roll angle and pitch angle, so that the vehicle It is possible to suppress deterioration of control of the running behavior.

Further, in the present embodiment, when the fluid pressure type active suspension 10 equipped with the vehicle body inclination angle calculating device is taken as an example and explained, in the case where a series of processes concerning the calculation of the roll angle and the pitch angle is executed in the suspension control. However, it is also possible to use a separate routine that executes a series of processing relating to the calculation of the roll angle and the pitch angle at a unique interrupt timing. In this case,
Normally, since the wheel air pressure Pwi of each wheel gradually decreases, the roll angle and the pitch angle can be accurately calculated without hindering other controls even if the frequency of executing the roll angle and the pitch angle is reduced. Therefore, the electronic control unit 100
The calculation load of can be reduced. Moreover, if the roll angle and pitch angle calculation processing is an original routine, the calculation result is not limited to suspension control, damping force switching control, roll rigidity distribution ratio control, four-wheel steering control, four-wheel drive control, brake control. , It can be used whenever necessary for engine control.

[0086]

As described above in detail, according to the vehicle body inclination angle calculating device of the first aspect, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the vehicle body inclination angle. Since it is reflected in the calculation, it is possible to calculate the vehicle body inclination angle that is close to the actual vehicle body inclination angle.

According to the vehicle body inclination angle calculating device of the second aspect, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the calculation of the roll angle of the vehicle body. A roll angle close to the roll angle can be calculated.

According to the vehicle body inclination angle calculating device of the third aspect, even if the vertical rigidity of the wheel changes for some reason, the change in the vertical rigidity of the wheel is reflected in the calculation of the pitch angle of the vehicle body. A pitch angle close to the pitch angle can be calculated.

According to the vehicle body inclination angle calculating device of the present invention, even if the air pressure of the wheel fluctuates and the vertical rigidity of the wheel changes, the change of the vertical rigidity of the wheel is reflected in the calculation of the vehicle body inclination angle. Therefore, it is possible to calculate the vehicle body inclination angle that is close to the actual vehicle body inclination angle.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of a fluid pressure type active suspension 10 equipped with a vehicle body inclination angle calculating device of the present invention.

2 is a block diagram showing an electronic controller 100 for controlling the pilot pressure controller and the pressure control valve shown in FIG. 1. FIG.

FIG. 3 is the first half of a general flowchart showing the suspension control flow achieved by the electronic control unit 100 shown in FIG.

FIG. 4 is the latter half of the general flowchart showing the suspension control flow.

FIG. 5 is a step S5 of the flowchart shown in FIG.
6 is a flowchart showing a part of a routine of active calculation performed at 0.

FIG. 6 is step S5 of the flowchart shown in FIG.
6 is a flowchart showing the rest of the routine of the active calculation performed at 0.

FIG. 7 is a graph showing the relationship between the unsprung resonance frequency of the vehicle and the wheel air pressure Pwi.

FIG. 8 is a graph showing a relationship between wheel air pressure Pwi and vehicle roll rigidity kr.

FIG. 9 is a graph showing the relationship between wheel air pressure Pwi and vehicle pitch stiffness kp.

FIG. 10 is a graph showing a relationship between a vehicle speed V and a target displacement amount Rxh.

FIG. 11 is a graph showing the relationship between longitudinal acceleration Gx and pitch target value Rxp.

FIG. 12 is a graph showing the relationship between lateral acceleration Gy and roll target value Rxr.

FIG. 13 is a graph showing a relationship between longitudinal acceleration Gx and target pressure Pgx.

FIG. 14 is a graph showing a relationship between lateral acceleration Gy and target pressure Pgy.

FIG. 15 is a graph showing a relationship between a vehicle speed V and a steering angular velocity θ ′ and a predicted lateral acceleration change rate Gypr.

[Explanation of symbols]

 10 ... Fluid pressure type active suspension 12 ... Connection passage 14 ... Working fluid discharge passage 16 ... Engine 18 ... Pump 20 ... Working fluid supply passage 22 ... Pressure control valve 24 ... Switching control valve 24a ... Switching position 24b ... Switching position 24c ... Switching position 26 ... Branch passage 28 ... Fixed throttle 30 ... Variable throttle 32 ... Connection passage 34 ... Throttle 36 ... Actuator 37 ... Pressure sensor 38 ... Working fluid chamber 46 ... Shutoff valve 48 ... Pilot pressure control device 50 ... Connection passage 52 ... Fixed throttle 54 ... Variable diaphragm 60 ... Accumulator 100 ... Electronic control device 102 ... Microcomputer 118 ... Vehicle height sensor 120 ... Vehicle speed sensor 122 ... Front / rear G sensor 124 ... Lateral G sensor 126 ... Steering angle sensor 128 ... Vehicle height setting switch 140 ... Wheel speed sensor Vw ... rotational speed Wh ... wheels kp ... Pitch rigidity kr ... roll stiffness λ0 ... pitch angle φ0 ... roll angle

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B62D 103: 00 105: 00 111: 00 123: 00 131: 00

Claims (4)

[Claims] 1. A device for calculating a vehicle body inclination angle, comprising: an acceleration detecting means for detecting an acceleration acting on the vehicle body; and a wheel vertical rigidity detecting means for detecting a vertical rigidity of a wheel of the vehicle. A vehicle body inclination angle calculation device comprising: an inclination angle calculation means for calculating a vehicle body inclination angle based on the detected vertical rigidity and acceleration. 2. The vehicle body inclination angle calculating device according to claim 1, wherein the acceleration detecting means detects a lateral acceleration acting on the vehicle body, and the inclination angle calculating means calculates the lateral acceleration and the lateral acceleration. A vehicle body inclination angle calculating device for calculating a roll angle of a vehicle body based on the vertical rigidity. 3. The vehicle body inclination angle calculating device according to claim 1, wherein the acceleration detecting means detects longitudinal acceleration acting on the vehicle body, and the inclination angle calculating means calculates the longitudinal acceleration and the longitudinal acceleration. A vehicle body inclination angle calculation device for calculating a vehicle body pitch angle based on the vertical rigidity. 4. The vehicle body inclination angle calculating device according to claim 1, wherein the wheel vertical stiffness detecting means detects an air pressure of a wheel of the vehicle.