JPH089287B2 - Electronically controlled suspension system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension of a vehicle such as an automobile,
More specifically, the present invention relates to an electronically controlled suspension device that controls the attitude of a vehicle body.

[Prior Art] Various devices for controlling the posture of a vehicle body have been conventionally proposed in order to improve riding comfort and steering stability of a vehicle such as an automobile. For example, as described in Japanese Patent Laid-Open No. 61-193907, the posture of the vehicle body changes according to the target mathematical model based on the detected value of the lateral acceleration or longitudinal acceleration of the vehicle and the set value set according to the driver's preference. The response amount is calculated, and the target stroke (target vehicle height) between the unsprung part and the sprung part of the vehicle is calculated according to this attitude change response amount, and according to the deviation between this target stroke and the actual stroke detection value. A suspension device configured to control an actuator provided for each wheel has already been proposed.

According to such a suspension device, since the target posture change amount of the vehicle body is set according to the acceleration of the vehicle body, the posture of the vehicle body is controlled according to the acceleration of the vehicle body, so that the vehicle body posture is controlled even when the vehicle turns or accelerates or decelerates. It is possible to maintain a stable posture.

[Problems to be Solved by the Invention] However, in the conventional electronically controlled suspension device as described in the above-mentioned Japanese Patent No. 61-193907, even when a very rapid turning or acceleration / deceleration is performed, If the posture control is performed so that the posture does not change so much, the driver cannot recognize that the turning or acceleration / deceleration conditions of the vehicle have reached the limit driving condition, and therefore the turning or acceleration / deceleration of the vehicle is not possible. When the condition (1) exceeds the limit running condition, a drastic change in vehicle behavior such as drift may occur.

In view of the above-mentioned problems in the conventional electronically controlled suspension device, the present invention can maintain the posture of the vehicle body in a stable posture when turning and acceleration / deceleration are not extremely rapid, It is an object of the present invention to provide an improved electronically controlled suspension device that allows a driver to accurately recognize that when acceleration / deceleration is performed very rapidly and the condition approaches the limit running condition, the change in the posture of the vehicle body allows the driver to accurately recognize this. Has an aim.

[Means for Solving the Problems] According to the present invention, the above-described objects are provided corresponding to the respective wheels M1 as shown in the basic configuration diagram of FIG. A fluid actuator M2 that increases or decreases the vehicle height of a corresponding portion by being performed, and a fluid supply / discharge means M3 that supplies / discharges a working fluid to / from the fluid actuator,
Running state detection means for detecting or estimating vehicle body acceleration
M4, target posture change amount setting means M5 for setting a target posture change amount of the vehicle body in accordance with the acceleration estimated or detected by the traveling state detection means, and posture change for detecting or estimating the posture change amount of the vehicle body An amount detection means M6 and a control means M7 for controlling the fluid supply / discharge means so that the attitude change amount of the vehicle body matches the target attitude change amount on the basis of the deviation between the attitude change amount of the vehicle body and the target attitude change amount. In the electronically controlled suspension device having the above-mentioned control means, when the magnitude of the acceleration detected or estimated by the running state detection means exceeds a predetermined value, the control means compares the acceleration magnitude with the predetermined value or less. The electronically controlled suspension device is configured to set the target posture change amount so that the ratio of the target posture change amount to the acceleration becomes high. It is made.

[Operation of the Invention] According to the above configuration, the control means M7 sets the target posture change amount of the vehicle body according to the acceleration when the magnitude of the acceleration estimated or detected by the traveling state detection means M4 is less than or equal to a predetermined value. However, when the magnitude of acceleration exceeds a predetermined value, the target posture change amount is set so that the ratio of the target posture change amount to the acceleration is higher than that when the acceleration magnitude is less than or equal to the predetermined value. There is.

Therefore, when turning or acceleration / deceleration is not performed very rapidly and the magnitude of acceleration is below a predetermined value, the posture of the vehicle body during turning or acceleration / deceleration is maintained in a stable posture, and turning or acceleration / deceleration is extremely difficult. When the magnitude of acceleration / deceleration exceeds a predetermined value and the ratio of the target attitude change amount to the acceleration is increased as compared with the case where the magnitude of the acceleration is less than the predetermined value, the attitude of the vehicle body is rolled. Since the vehicle is controlled to a target attitude in which pitching and pitching become large, and as a result, a relatively large attitude change of the vehicle body occurs, the driver can be made aware that the vehicle turning and acceleration / deceleration conditions are approaching the limited travel conditions. .

[Supplementary Description for Solving the Problem] According to one embodiment of the present invention, the electronically controlled suspension device further includes a target of the attitude of the vehicle body according to the rate of change in acceleration estimated or detected by the traveling state detection means. The control means has a target change rate setting means for setting a change rate and an attitude change rate detecting means for detecting or estimating a change rate of the attitude of the vehicle body, and the control means controls the deviation between the attitude change amount of the vehicle body and the target attitude change amount. Based on the difference between the change rate of the vehicle body attitude and the target change rate, the change rate of the vehicle body attitude matches the target change rate based on the deviation between the change rate of the vehicle body attitude and the target change rate. When the magnitude of the acceleration detected or estimated by the running state detecting means exceeds a predetermined value, the target posture change amount with respect to the acceleration is compared with the case where the magnitude of the acceleration is less than the predetermined value. When the target posture change amount is set so that the ratio becomes high, and the magnitude of the rate of change of acceleration detected or estimated by the running state detection means exceeds a predetermined value, the magnitude of the rate of change of acceleration is equal to or less than the predetermined value. The target change rate is set so that the ratio of the target change rate to the change rate of acceleration is higher than that of.

With this configuration, even when the vehicle turns or accelerates or decelerates relatively rapidly, the posture of the vehicle body is reliably controlled without a response delay, and the acceleration of the vehicle body increases even when the vehicle turns or accelerates or decelerates very rapidly. Of the vehicle body depending on the size of the vehicle and its rate of change, thereby making it possible for the driver to more accurately recognize that the conditions for turning and accelerating and decelerating the vehicle are approaching the limit running conditions. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[Embodiment] FIG. 2 is a schematic configuration diagram showing one embodiment of the electronically controlled suspension device according to the present invention, and FIG. 3 is an air circuit diagram of the embodiment shown in FIG.

The electronically controlled suspension device of the illustrated embodiment has a front left wheel, a front right wheel, a rear left wheel, respectively, connected to an air circuit AC.
It has suspensions 1FL, 1FR, 1RL, 1RR for the right rear wheel, and these suspensions have gas springs 2FL, 2FR,
2RL, 2RR and shock absorbers 3FL, 3FR, 3RL, 3RR are provided.

As shown in Fig. 3, gas springs 2FL, 2FR, 2R
L and 2RR respectively have main gas chambers 4FL, 4FR, 4RL and 4RR and sub gas chambers 5FL, 5FR, 5RL and 5RR, and part of the main gas chambers are formed by diaphragms 6FL, 6FR, 6RL and 6RR, respectively. Therefore, the vehicle height of the corresponding portion can be adjusted by supplying and exhausting air to and from the main gas chambers 4FL, 4FR, 4RL, 4RR. Actuator M2 is configured.

Each of the gas springs 2FL, 2FR, 2RL, 2RR has an actuator 7FL, 7FR, 7RL, 7RR for switching the spring constant. By driving these actuators, communication between the corresponding main gas chamber and sub gas chamber is established. Alternatively, the degree of communication between them is controlled to be switched, whereby the spring constant is "low",
It is possible to change to three levels, "medium" and "high". Also, shock absorbers 3FL, 3FR, 3RL, 3
RR is actuator 8FL, 8F for switching damping force respectively
R, 8RL, 8RR, and driving these actuators controls the effective passage cross-sectional area of the orifices not shown in the figures provided on the pistons 3a, 3b, 3c, 3d, and thus the cylinder 3e. , 3f, 3g, 3h changes the flow resistance when the oil flows through the orifice, which makes it possible to change the damping force in three steps: "low", "medium", and "high". ing.

The air circuit AC is provided with a compressor 10 as a supply source of compressed air supplied to each gas spring. The compressor 10 is driven by a motor 9, and its discharge side is connected to an air dryer 14 and an exhaust on-off valve 16 via a check valve 12 for preventing backflow. The air dryer 14 is filled with a desiccant such as silica gel that removes the moisture in the compressed air passing through it. The air dryer 14 has a fixed throttle 18 and a check valve 20 for preventing backflow.
It is connected to the on-off valve 22 for supply and the on-off valve 24 for connection via. The on-off valve 22 is connected to a relief valve 25 set to a predetermined pressure, is connected to a high-pressure reservoir 28 for the front wheels via an on-off valve 26 for the high-pressure reservoir, and is connected via an on-off valve 30 for the high-pressure reservoir to the rear. It is connected to a high pressure reservoir 32 for the wheel. These reservoirs 28 and 32 are provided with pressure sensors 34 and 36, respectively, for detecting the pressure of air in the corresponding reservoirs, and relief valves 38 and 40 set to a predetermined pressure. Further, the supply opening / closing valve 22 is connected to the main gas chambers 4FL, 4F via the supply opening / closing valves 42, 44, 46, 48, respectively.
It is connected to R, 4RL, and 4RR. Main gas chamber 4FL, 4FR, 4R
Pressure sensors 50, 52, 54 and 56 for detecting the pressure of the internal air are connected to L and 4RR, respectively.

The main gas chambers 4FL and 4FR for the left and right front wheels are connected to a low-pressure reservoir 62 for the front wheels via open / close valves 58 and 60 for exhaust, respectively. Similarly, the main gas chambers 4RL and 4RR for the left and right rear wheels are connected to the low-pressure reservoir 68 for the rear wheels via the on-off valves 64 and 66 for exhaust, respectively. The low-pressure reservoirs 62 and 68 for the front wheels and the rear wheels are always connected in communication with each other. Further, pressure sensors 70 and 72 for detecting the pressure of the air in the corresponding reservoirs are connected to the reservoirs 62 and 68, respectively, and in particular, the reservoir 62 is provided with a relief valve 74 set to a predetermined pressure. ing. Further, the reservoirs 62 and 68 are connected to the opening / closing valve 24 for connection, and are connected to the suction side of the compressor 10 via the opening / closing valve 76 for suction. A check valve 78 that allows only the flow of air from the atmosphere to the compressor is provided on the suction side of the compressor 10.

Thus, the air circuit AC constitutes the fluid supply / discharge means M3 shown in FIG.

The air circuit AC may be configured as a completely closed circuit by omitting the check valve 78, in which case air or another gas such as nitrogen gas may be enclosed in the air circuit. Further, in the illustrated embodiment, the on-off valves 16, 22, 24, 26,
Although 30, 42 to 48, 58 to 66 and 76 are normally closed on-off valves, these on-off valves may be normally open on-off valves. Further, in the illustrated embodiment, the high pressure reservoirs 28 and 32 and the low pressure reservoirs 62 and 68 are individually provided for the front wheels and the rear wheels, but one high pressure reservoir common to the front wheels and one high pressure reservoir to the rear wheels are provided. A reservoir and a low pressure reservoir may be provided.

As shown in FIG. 2, vehicle height sensors 80, 82, 84, 86 for detecting vehicle heights of corresponding portions are provided at positions corresponding to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively. It is provided. These vehicle height sensors output a vehicle height signal as a deviation of the actual vehicle height from a predetermined reference vehicle height. Further, a steering angle sensor 90 for detecting the steering angle of the steering wheel 88, an acceleration sensor 92 for detecting the lateral and longitudinal accelerations of the vehicle body, and a vehicle speed based on the rotational speed of the output shaft of the transmission (not shown) are detected. Vehicle speed sensor 93,
A door switch 94 provided for each door of the vehicle to detect the closed state of the door, a neutral switch 95 to detect that the transmission shift position is in the neutral position, and an intake air amount of the internal combustion engine not shown in the figure are controlled. Each throttle opening sensor 96 for detecting the opening of the throttle valve is provided. Further, there are provided a vehicle height high switch 97 and a vehicle height low switch 98 which are operated by an occupant of the vehicle to instruct the target vehicle height to “high” or “medium” and “medium” or “low” according to the vehicle speed, respectively. .

The steering angle sensor 90, the acceleration sensor 92, and the vehicle speed sensor 93 constitute the traveling state detecting means M4 of FIG. 1, and the vehicle height sensors 80 to 86 are the vehicle height high switch 97 and the vehicle height low switch 98.
The attitude change amount detecting means M6 shown in FIG.

Next, the electric system of the illustrated embodiment will be described with reference to the block diagram shown in FIG.

Air circuit AC mentioned above and each suspension 1FL, 1FR, 1R
L and 1RR are controlled by the electronic control circuit 100. As shown in FIG. 4, the electronic control circuit 100 includes a well-known CPU 102, R
The OM104 and RAM106 are configured as the central elements of the logical operation circuit, and these elements are the actuator drive circuit 10
8. The valve drive circuit 110, the sensor input circuit 112, the level input circuit 114, and the common bus 116 are connected to each other.

The CPU 102 receives signals from the pressure sensors 34, 36, 50 to 56, 70, 72, vehicle height sensors 80 to 86, steering angle sensor 90, acceleration sensor 92, vehicle speed sensor 93, and throttle opening sensor 96 as a sensor input circuit 112. Further, signals from the door switch 94, the neutral switch 95, the vehicle height high switch 97 and the vehicle height low switch 98 are input via the level input circuit 114. In addition, the CPU 102
Drive signals are output to the compressor motor 9, the spring constant switching actuators 7FL, 7FR, 7RL, 7RR and the damping force switching actuators 8FL, 8FR, 8RL, 8RR via the actuator driving circuit 108 based on the data in the ROM104 and RAM106. Further, through the valve drive circuit 110, the exhaust opening / closing valve 16, the supply opening / closing valve 22, the connecting opening / closing valve 24, the high pressure reservoir opening / closing valves 26 and 30, the air supply opening / closing valves 42 to 48, and the exhaust opening / closing valve 58. ~ 66, a drive signal is output to the intake on-off valve 76, and thereby each suspension 1FL, 1FR, 1RL, 1RR is controlled.

The ROM 104 stores maps corresponding to the graphs shown in FIGS. 10 to 21 as described later. As will be described later in detail, the electronic control circuit 100 constitutes the target change amount setting means M5 and the control means M7 shown in FIG.

Next, various processes performed in the electronic control circuit 100 will be described with reference to the flowcharts shown in FIGS. 5 to 9 and the graphs shown in FIGS. 10 to 21.

FIG. 5 is a general flow chart showing an example of control of the suspension device according to the present invention, and FIGS. 6 to 9 are executed at steps 200, 400, 500 and 600 of the flow chart shown in FIG. 5, respectively. It is a flowchart which shows the detail of the process performed.

The control according to the flowchart shown in FIG. 5 starts when the main relay is closed by an ignition switch (not shown), and ends when each on-off valve is closed when the main relay is opened.

First, at step 105, variables such as data stored in the RAM 106 are initialized, and at next step 110, signals from the above-mentioned sensors are read.

In the next step 200, gas springs of suspensions 1FL, 1FR, 1RL, 1RR are performed in response to the roll of the vehicle body.
Among the air supply / discharge control for 2FL, 2FR, 2RL, 2RR, the feedforward control calculation processing is executed according to the flowchart shown in FIG. This feed-forward control calculates the lateral acceleration GRLM of the vehicle body from the vehicle speed and the steering angle, and adjusts the atmospheric pressure of the gas springs 2FL, 2FR, 2RL, 2RR according to the estimated lateral acceleration GRLM, thereby It is intended to prevent or suppress rolls in advance.

In the next step 400, in the air supply / discharge control for the gas spring, the feedback control calculation process is executed according to the flowchart shown in FIG. 7. This feedback control is intended to stabilize the posture of the vehicle body by adjusting the atmospheric pressure of the gas spring based on the actual acceleration of the vehicle body.

In the next step 500, the total pressure control amount for each suspension, that is, the sum of the pressure control amounts calculated in steps 200 and 400 is calculated (see FIG. 8).

In the next step 600, based on the total pressure control amount calculated in step 500, the high pressure reservoir opening / closing valves 26 and 3 are
0, the drive duty for opening and closing a necessary on-off valve among the on-off valves 42 to 48 for air supply, the on-off valves 58 to 66 for exhaust, and the on-off valve for intake 76 is calculated (see FIG. 9).

Next, each process in steps 200 to 600 will be described in more detail.

FIG. 6 is a flowchart showing the calculation processing of the feedforward control executed in step 200.

First, in step 210, filtering processing of each signal is executed. That is, the data read this time is X
(N), and the value after the previous filtering process is Y (n
-1) and the filtering constant If (= 1 to 256), the output Y (n) by the filtering process is expressed by the following equation.

It should be noted that this process is a process for canceling the noise component of the detected data or for averaging the fluctuation of the data having a frequency equal to or higher than a predetermined value.

In the next step 220, it is determined whether or not all the doors are closed based on the signal from the vehicle door switch 94, and in step 230, the signal from the neutral switch 95 is used. Based on the signal from the throttle opening sensor 96, it is determined whether or not the throttle valve is fully closed based on the signal from the throttle opening sensor 96. At
Among the on-off valves for suspension control, on-off valves 26 and 30 for high pressure reservoir, on-off valves 42 to 48 for air supply, on-off valve for exhaust 5
Whether or not the vehicle height control for the suspension is being performed is determined by 8 and 66. In step 260, it is determined whether or not the vehicle speed V is less than or equal to a predetermined value V ₀ based on the signal from the vehicle speed sensor 93. Is done.

Thus, in steps 220, 230, 240, and 260, factors that change the posture of the vehicle body (for example, opening and closing doors for passengers to get in and out of, the shift position of the transmission indicating the transmission of driving force to the tires, the internal combustion engine, The intake air amount corresponding to the output of the period, the vehicle speed which is one of the variables indicating the running state of the vehicle)
Is determined, and it is determined in step 250 whether or not the air supply / discharge for adjusting the atmospheric pressure of the gas spring is performed.

If all of the determinations in steps 220 to 260 are positive, the posture of the vehicle body is in a stable state, and the pressures of the gas springs 2FL, 2FR, 2RL, 2RR have large fluctuations. Since it can be estimated that the pressure is stable, the pressure detected by each of the pressure sensors 50 to 56 in the next step 270 is the reference pressure PFLA, PFRA, P, respectively.
It is set as RLA and PRRA and stored in the RAM 106.

The filtering constant If in step 210 is set so that these pressures are values lower than the filtering frequency in step 210, for example, values filtered by a low-pass filter of 5 Hz.

If a negative determination is made in any of steps 220-260, step 270 is not executed and therefore the reference pressure PFL.
A, PFRA, PRLA, PRRA are not updated, and conversely 220 to 260,
The reference pressure is always updated as long as all of the conditions are satisfied.

If a negative determination is made after step 270 is completed or in any of steps 220-260, the next step 280
At this time, the estimated lateral acceleration RL of the vehicle body is calculated from the vehicle speed V and the steering angle θ based on the map corresponding to the graph shown in FIG.

In the next step 290, the rate of change RL of the estimated lateral acceleration of the vehicle body is calculated based on the map corresponding to the graph shown in FIG. 11 based on the vehicle speed V and the steering angular velocity which is the differential value of the steering angle θ.
Is calculated. In this case, the steering angular velocity may be a difference value of the steering angle θ in a predetermined time.

In the graphs of FIG. 10 and FIG. 11, only two and eight broken lines are shown, but two and eight or more broken lines may be set, respectively, and between each broken line. The value of is calculated by interpolation calculation.

In the next step 300, the predicted lateral acceleration GRLM is calculated according to the following equation.

Here, m and h are constants, which are values that can be obtained by, for example, experiments in order to predict the roll of the vehicle body.

In the next step 310, based on the map corresponding to the graph shown in FIG. 12 from the predicted lateral acceleration GRLM calculated in step 300, each gas spring 2FL, 2FR, 2RL, 2
Predicted pressure change amounts ΔPFLM, ΔPFRM, ΔPRLM, and ΔPRRM that are estimated to change due to lateral acceleration are calculated.

As shown in FIG. 12, the predicted pressure change amount is expressed as follows.

.DELTA.PFLM = a.multidot.GRLM .DELTA.PFRM = -a.multidot.GRLM .DELTA.PRLM = b.multidot.GRLM .DELTA.PRRM = -b.multidot.GRLM where a and b are coefficients for correcting variations in various characteristics of the suspension, and are respectively expressed as follows.

Where W is the sprung weight, H is the height of the center of gravity,
Tf and Tr are the treads of the front and rear wheels, respectively, and Rf
And Rr are the arm ratios of the front and rear wheels respectively, Af and Ar are the pressure receiving areas of the pistons of the suspensions of the front and rear wheels respectively, L is the wheel base, and Lr is between the rear wheel and the center of gravity. It is a distance. Also, Kf is (L / Lr)> Kf
It is an arbitrary constant set in the range of ≧ 1.0. This Kf
Represents the share load ratio of the front wheels, and the steer characteristic of the vehicle can be arbitrarily set by changing this value. For example, when Kf is 1.0, the front wheel shared load ratio is 50%.

As shown in FIG. 12, -i≤GRLM≤i (i is a positive constant) in order to prevent repeated minute adjustments due to fluctuations in calculated values, detection errors, noise, etc. )
If, the predicted pressure change amount ΔPFLM, ΔPFRM, ΔP
A dead zone in which RLM and ΔPRRM are set to 0 is provided.

In the next step 320, the target pressures PFLM and PF of the gas springs are calculated based on the calculation results in steps 270 and 310.
RM, PRLM and PRRM are calculated according to the following equation.

PFLM = ΔPFLM + PFLA PFRM = ΔPFRM + PFRA PRLM = ΔPRLM + PRLA PRRM = ΔPRRM + PRRA In the next step 330, the deviation EFL, EF of each pressure
R, ERL, and ERR are calculated according to the following equations.

EFL = PFLM-PFL EFR = PFRM-PFR ERL = PRLM-PRL ERR = PRRM-PRR In the above equation, PFL, PFR, PRL and PRR are pressure sensors 50 provided in the main gas chambers 4FL, 4FR, 4RL and 4RR, respectively.
Is the pressure detected by ˜56 after filtering.

In the next step 340, in order to convert the deviation of each pressure calculated in step 330 into a controlled variable, the following step 35
The gain k1 of the calculation of the feedforward control executed at 0 is based on the map corresponding to the graph shown by the broken line in FIG. 13, for example, and the difference between the predicted lateral acceleration GRLM and the actual lateral acceleration GRL is obtained. Is calculated according to.

In this case, as shown in Fig. 13, the absolute value | GRLM +
When GRL | is q or less, k1 is 0, and when QRL is Q or more, k1 is T. In the meantime, k1 gradually increases as | GRLM + Gr1 | increases. Therefore, the greater the difference between the predicted lateral acceleration GRLM and the actual lateral acceleration GRL, the higher the degree of contribution of the feedforward control to the control for each suspension.

In the next step 350, based on the deviations ERL, EFR, ERL, ERR of the pressures calculated in step 330 and the gain k1 calculated in step 340, each suspension 1RL, Feedforward pressure control amount for 1FR, 1RL, 1RR C1FL, C1FR, C1R
L and C1RR are calculated.

C1FL = k1EFL C1FR = k1EFR C1RL = k1ERL C1RR = k1ERR FIG. 7 is a flowchart showing the calculation process of feedback control executed in step 400.

First, at step 410, based on the vehicle heights XFL, XFR, XRL, and XRR of the parts corresponding to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel detected by the vehicle height sensors 80 to 86, Heave amount (vertical displacement amount) XH, pitch amount X according to the formula
P, roll amount XR, and twist amount XW are calculated.

XH = (XFR + XFL) + (XRR + XRL) XP = (XFR + XFL)-(XRR + XRL) XR = (XFR-XFL) + (XRR-XRL) XW = (XFR-XFL)-(XRR-XRL) At the next step 420. Then, based on the respective mode quantities XH, XP, XR, XW calculated in step 410, the deviations EH, EP, ER, EW of the respective mode quantities are calculated according to the following equations.

EH = XHM-XH EP = XPM-XP ER = XRM-XR EW = XWM-XW In the above equation, XHM is the target heave amount, which is the mode (H-AUT) set by the vehicle speed and vehicle height high switch 97.
O) or the mode (N-AUTO) set by the vehicle height low switch 98, and is calculated based on the map corresponding to the graph shown in FIG. Further, XPM and XRM are the target pitch amount and the target roll amount, respectively. Based on the actual lateral acceleration GFR and the actual lateral acceleration GRL detected by the acceleration sensor 92, respectively, the graphs shown in FIGS. It is calculated based on the corresponding map. XWM is a target twist amount, which may be zero.

In the next step 430, each mode quantity XH, XP, X
Based on the differential values H, P, R, W of R, XW, the deviations H, P, R, W of the rate of change of each mode amount are calculated according to the following equations.

In addition, H, P, R, and W are XH, XP, XR, and
It may be a difference value of XW during a predetermined time.

H = HM-HP = PM-PR = RM-RW = WM-W where HM is the target change rate of the heave amount, which may be zero. PM and RM are the target change rate of the pitch amount and the target change rate of the roll amount, respectively, and correspond to the graphs shown in FIGS. 17 and 18 from the change rate FR of the longitudinal acceleration and the change rate RL of the lateral acceleration, respectively. It is calculated based on the map. Further, WM is a target change rate of the twist amount, which may be zero.

As shown in FIGS. 15 to 18, the target pitch amount XPM is the first predetermined value g of the actual longitudinal acceleration GFR of the vehicle body.
Between frr1 (negative constant) and the second predetermined value gfrr2 (negative constant) and between the first predetermined value gfrf1 (positive constant) and the second predetermined value gfrf2 (positive constant). Is set so that the ratio of the target pitch amount XPM to the actual longitudinal acceleration GFR is higher than that in the case where the actual longitudinal acceleration GFR is greater than or equal to the first predetermined value gfrr1 and less than or equal to the first predetermined value gfrf1, respectively. As for the target roll amount XPM, the actual lateral acceleration GRL of the vehicle body is also the first predetermined value grll1 (negative constant) and the second predetermined value grll2.
Between the (negative constant) and the first predetermined value grlr1 (positive constant) and the second predetermined value grlr2 (positive constant), the actual lateral acceleration GRL is the first. Predetermined value grll1
As described above, the ratio of the target roll amount XRM to the actual lateral acceleration GRL is set to be higher than when the first predetermined value grlr1 or less.

Similarly, the target change rate PM of the pitch amount and the target change rate RM of the roll amount are respectively a first predetermined value gpmr1 (negative constant), grml1 (negative constant) and a second predetermined value gpmr2 (negative constant), between grml2 (negative constant) and the first predetermined value g
Between pmf1 (positive constant), grmr1 (positive constant) and the second predetermined value gpmf2 (positive constant), grmr2 (positive constant), the target change rate PM of pitch amount and roll amount The target change rate PM of the pitch amount relative to the change rate FR of the actual longitudinal acceleration is higher than the target change rate RM of the first predetermined value gpmr1, grml1 or more and the first predetermined value gpmf1, grmr1 or less, respectively. The ratio of the target change rate RM of the roll amount to the actual change rate RL of the lateral acceleration is set to be high.

The target pitch amount XPM is the actual longitudinal acceleration GFR of the vehicle body.
Is smaller than the second predetermined value gfrr2, or becomes larger than the second predetermined value gfrf2, the absolute value thereof gradually decreases, and is set to 0 at the third predetermined values gfrr3 and gfrf3, respectively. However, the absolute value of the vehicle body having the target roll amount XRM gradually decreases as the actual lateral acceleration GRL becomes smaller than the second predetermined value grll2 or becomes larger than the second predetermined value grrlr2. The predetermined values grll3 and grlr3 are set to be 0.

Similarly, the target change rate PM of the pitch amount and the target change rate RM of the roll amount become smaller than the second predetermined values gpmr2, grmr2, respectively, or the second predetermined values gpmf2, gpmf2, gpmr2.
The absolute values of these values gradually decrease as they become larger than rmf2, and are set to zero at the third predetermined values gpmr3 and gpmf3, grmr3 and grmf3, respectively.

Further, in the illustrated embodiment, the third predetermined values gfrr3 and grll3 are transmitted to the electronic control circuit 100 when a wire harness (not shown) for transmitting the output signal of the acceleration sensor 92 is broken. It is set to a value that is substantially equal to the value of the abnormal signal that is input, and the third predetermined values gfrf3 and grlf3 are substantially the same as the value of the abnormal signal that is input to the electronic control circuit when the wire harness is short-circuited. Is set to a value equal to. Similarly, the third predetermined values gpmr3 and grml3 are the abnormal acceleration change rates as the instantaneous values calculated based on the abnormal acceleration values input to the electronic control circuit when the wire harness is broken, or the RAM 106. It is set to a value corresponding to the rate of change of the abnormal acceleration that deviates from the control range due to such abnormalities. The third predetermined values gpmf3 and grmr3 are the accelerations input to the electronic control circuit when the wire harness is broken. Is set to a value corresponding to an abnormal acceleration change rate as an instantaneous value calculated based on the abnormal value of, or an abnormal acceleration change rate that deviates from the control range due to an abnormality of the RAM 106 or the like.

In step 440, which is performed after step 430,
Next step to convert the deviation of each mode into a controlled variable
The feedback gains k2H, k2P, k2R, k2W (generally referred to as k2) and k3H, k3P, k3R, k3W (generally referred to as k3) in the formula of the calculation executed at 450 are indicated by the solid line in FIG. It is calculated according to the difference between the predicted lateral acceleration GRLM and the actual lateral acceleration GRL based on the map corresponding to the graph shown in FIG.

In this case, as shown in Fig. 13, the absolute value | GRLM-
When GRL | is less than or equal to q, k2 and k3 are T, and when greater than or equal to Q, k2 and k3 are t, and between them, k2 and k3 are increased in accordance with the increase of the absolute value | GRLM-Gr1 |. It is gradually decreasing. Therefore, the smaller the difference between the predicted lateral acceleration GRLM and the actual lateral acceleration GRL, the higher the contribution degree of the feedback control to the control for each suspension.

In the next step 450, the deviations EH, EP, ER, EW of the respective mode quantities calculated in step 420 and the step
Deviation H of change rate of each mode amount calculated in 430,
From P, R and W, the feedback amounts DH, DP, DR and DW of each mode are calculated according to the following equations.

DH = k2H * EH + k3H * H + k4H DP = k2P * EP + k3P * P + k4P DR = k2R * ER + k3R * R + k4R DW = k2W * EW * k3W * W + k4W k4H, k4P and k4R and k4R and k4R, k4R and k4R, respectively.

In the next step 460, each suspension 1FL, 1FR, 1R is calculated according to the following equation based on the feedback amounts DH, DP, DR, DW calculated in step 450.
Feedback control amount DFL, DFR, DR for L, 1RR
L and DRR are calculated.

DFL = 1/4 (kOH ・ DH + 2k OP ・ Lf ・ DP-kOR ・ DR + kOW ・ DW) DFR = 1/4 (kOH ・ DH + 2k OP ・ Lf ・ DP + kOR ・ DR + kOW ・ DW) DRL = 1/4 (kOH ・ DH + 2k OP ・ (1-Lf) ・ DP-kOR ・ DR + kOW ・ DW) DRR = 1/4 (kOH ・ DH + 2k OP ・ (1-Lf) ・ DP-kOR ・ DR + kOW ・ DW) where kOH, kOP, kOR, kOW Is a constant coefficient,
Lf is a distribution coefficient between the front and rear wheels that considers the position of the center of gravity of the vehicle body in the wheel base.

In the next step 470, based on the feedback control amounts DFL, DFR, DRL, DRR calculated in step 460, the pressure control amounts C2FL, C2FR, C2RL, C2RR by feedback are calculated according to the following equations. .

C2FL = PFL, a2FL, DFL C2FR = PFR, a2FR, DFR C2RL = PRL, a2RL, DRL C2RR = PRR, a2RR, DRR In the above equation, PFL, PFR, PRL and PRR are the main gas chamber 4F.
The pressure is a pressure detected by the pressure sensors 50 to 56 provided in L, 4FR, 4RL, and 4RR and is a value that has been filtered. Further, a2FL, a2FR, a2RL, and a2RR are constant coefficients.

In step 510 shown in FIG. 8, step 350
The feedforward pressure control amounts C1FL, C1FR, C1RL, and C1RR calculated in step 470 and the feedback pressure control amounts C2FL and C2F calculated in step 470.
Based on R, C2RL, C2RR, the total pressure control amounts CFL, CFR, CRL, CRR for each suspension are calculated according to the following formulas.

CFL = C1FL + C2FL CFR = C1FR + C2FR CRL = C1RL + C2RL CRR = C1RR + C2RR FIG. 9 is a step of the flowchart shown in FIG.
6 is a flowchart showing a calculation process of an on-off valve control amount performed at 600.

In step 610, the main gas chamber 4FL based on the total pressure control amount CFL, CFR, CRL, CRR calculated in step 510,
Opening time of the high pressure reservoir opening / closing valves 26 and 30, the air supply opening / closing valves 42 to 48, or the exhaust opening / closing valves 58 to 66 in order to adjust the pressure in the 4FR, 4RL, and 4RR (open state is maintained. Time) TF
L, TFR, TRL, and TRR are calculated according to the following equations.

On-off valve for increasing pressure, that is, on-off valve 26 for high pressure reservoir,
30 and air supply on-off valves 42 to 48 TFL = (aF / φ) ・ (CFL / PFH) TFR = (aF / φ) ・ (CFR / PFH) TRL = (aR / φ) ・ (CRL / PRH ) TRR = (aR / φ) ・ (CRR / PRH) Open / close valve for pressure reduction, that is, for exhaust open / close valves 58 to 66 TFL = (bF / φ) ・ (CFL / PFH) TFR = (bF / φ) ) ・ (CFR / PFH) TRL = (bR / φ) ・ (CRL / PRH) TRR = (bR / φ) ・ (CRR / PRH) In the above equations, aF / φ and aR / φ are high pressure reservoirs. P1 (= PFH or PRH) of the internal pressure and the ratio P1 / P2 to the pressure P2 of the corresponding main gas chamber that is supplied with air from the reservoir
The calculation is performed based on the map corresponding to the graph shown in FIG. Further, bF / φ and bR / φ are graphs shown in FIG. 20 from the ratio P2 / P3 of the corresponding pressure P2 in the main gas chamber and pressure P3 in the low pressure reservoir for receiving the air discharged from the main gas chamber. Is calculated based on the map corresponding to the graph shown in the map corresponding to.

At the next step 620, based on the valve opening time calculated at step 610, the time (actual valve opening time) TFLU, TFRU, TRLU at which the on-off valve is actually opened according to the following formula:
TRRU (in case of pressure increase) and TFLD, TFRD, TRLD, T
RRD (for pressure drop) is calculated.

In case of opening / closing valve for pressure increase TFLU = αF ・ TFL + βFL TFRU = αF ・ TFR + βFR TRLU = αR ・ TRL + βRL TRRU = αR ・ TRR + βRR In case of opening / closing valve for pressure reduction TFLD = γF ・ TFL + δFR TFRD = γT ・ TFR + δFR ・ δFR ・ δFR TRL + δRL TRRD = γR ・ TRR + δRR αF, γF, αR, γR, βFL, βF in the above equations
R, βRL, βRR, ΔFL, ΔFR, ΔRL, and ΔRR are constants.

In the next step 630, the actual opening time TFLU, TFRU, TRLU, TRRU of each on-off valve calculated in step 620 is calculated.
(Collectively referred to as TU) or TFLD, TFRD, TRLD, TRRD
Guard processing (collectively referred to as TD) is performed. This process prevents the on-off valve from repeatedly opening and closing,
This is done to protect the on-off valve. For example, as shown in FIG. 21, the duty is 30
When the actual valve opening time TU or TD that is less than% is calculated, the actual valve opening time TU, TD is set to 0 and the duty is
When the actual valve opening time TU or TD exceeding 80% is calculated, the actual valve opening time TU, TD is fixedly set to the valve opening time corresponding to a duty of 80%.

In the next step 640, the opening / closing valves 26, 3 are opened at the actual valve opening time TU or TD after the guard processing in step 630.
The drive duty representing the valve opening time of 0, 42 to 48, 58 to 62 is set.

Thus, according to the illustrated embodiment, the target pitch amount XPM and the roll amount XRM, which are the target change amounts of the posture of the vehicle body, the target change rate PM of the pitch amount, which is the target change rate of the vehicle body posture, and the target change rate of the roll amount When the value of the acceleration signal from the acceleration sensor 92 exceeds the first predetermined value, the RM increases relatively rapidly with the increase in acceleration.

Therefore, when the acceleration of the vehicle body exceeds the first predetermined value, the roll rigidity and the pitch rigidity of the vehicle are reduced as compared with the case where the acceleration is less than the first predetermined value, so that a relatively small posture change of the vehicle body occurs. Therefore, the driver can surely recognize that the vehicle turning and acceleration / deceleration conditions have reached the limit travel condition.

Further, according to the illustrated embodiment, in the target pitch XPM, the roll amount XRM, the target change rate PM of the pitch amount, and the target change rate RM of the roll amount, the value of the acceleration signal from the acceleration sensor 92 is the second predetermined value. When it becomes an abnormal value between the third predetermined value, the absolute value of each target change amount is reduced and corrected to a low value,
When the value of the acceleration signal becomes the abnormal value of the third predetermined value abnormality, each target change amount is set to 0. Therefore, even if the value of the acceleration signal from the acceleration sensor 92 becomes an abnormal value, the attitude control of the vehicle body is continued, and the attitude control of the vehicle body based on the abnormal value is avoided, and the attitude of the vehicle body deteriorates significantly. This prevents the vehicle body from being reduced, and controls the vehicle body to a posture based on the target change amount that has been corrected for reduction or set to 0, that is, a posture that the vehicle body is substantially parallel to the road surface).

Further, since the first to third predetermined values are set as described above, the inclination between the first predetermined value and the second predetermined value as seen in FIGS. This can be set, and thereby the driver can be surely made aware that the conditions of turning and accelerating / decelerating the vehicle are approaching the limit travel conditions.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[Effects of the Invention] As is apparent from the above description, according to the present invention,
When turning or acceleration / deceleration is not performed very rapidly and the magnitude of acceleration is below a predetermined value, the posture of the vehicle body during turning or acceleration / deceleration is maintained in a stable posture, which ensures good steering stability of the vehicle. If the magnitude of acceleration exceeds a predetermined value due to extremely rapid turning or acceleration / deceleration, the target posture change with respect to acceleration will be greater than if the magnitude of acceleration is less than the predetermined value. By increasing the ratio of the amount, the posture of the vehicle body is controlled to a target posture in which roll and pitching become large, and as a result, a relatively large change in posture of the vehicle body occurs, so that the driver is required to turn or accelerate or decelerate the vehicle. It is possible to reliably recognize that the vehicle is approaching the limit running condition, and thus it is possible to prevent a sudden behavior change of the vehicle such as a drift from occurring.

Further, according to the present invention, when the magnitude of the acceleration exceeds a predetermined value, the target posture change amount is set such that the ratio of the target posture change amount to the acceleration becomes higher than that when the acceleration magnitude is less than or equal to the predetermined value. Since the target attitude change amount itself is not set to a high value, the attitude of the vehicle body changes abruptly when the magnitude of acceleration exceeds a predetermined value, and It is possible to reliably prevent a sudden deterioration in driving stability.

Further, according to the present invention, it is not determined whether or not the vehicle turning or acceleration / deceleration conditions are approaching the limit running conditions based on the vehicle speed, the steering angle, etc., but the magnitude of the actual acceleration of the vehicle body is set to a predetermined value. Since it is judged whether the condition of turning or adjusting immediately approaches the limit running condition depending on whether it exceeds the
Accurately determine whether the running condition of the vehicle is approaching the limit running condition regardless of the friction coefficient of the road surface, the wear condition of the tires, the loading capacity of the vehicle, etc., and drive the accurate judgment result as the posture change of the vehicle body Can be recognized by the person.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an electronically controlled suspension device according to the present invention, FIG. 2 is a schematic configurational diagram showing one embodiment of the electronically controlled suspension device according to the present invention, and FIG. 3 is shown in FIG. An air circuit diagram of the embodiment, FIG. 4 is a block diagram showing an electric system of the embodiment shown in FIGS. 1 and 2, and FIG. 5 is executed in the electronic control circuit shown in FIG. 6 is a general flow chart of the control routine to be executed, FIG. 6 is a flow chart showing the feedforward arithmetic processing performed in step 200 of the flow chart shown in FIG. 5, and FIG. 7 is a flow chart shown in FIG. FIG. 8 is a flow chart showing the calculation process of the feedback control performed in step 400, and FIG. 8 is a flow chart showing the calculation process of the total pressure control amount performed in step 500 of the flow chart shown in FIG. Chart, FIG. 9 is a flowchart showing the operation process of the on-off valve control amount performed At a step 600 in the flowchart shown in FIG. 5, 10
FIG. 11 is a graph corresponding to the map used to calculate the estimated lateral acceleration RL from the steering angle θ and the vehicle speed V. FIG. 11 is the rate of change of the estimated lateral acceleration from the steering angular velocity and the vehicle speed V. The graph corresponding to the map used to compute
Fig. 12 shows the predicted pressure change ΔPFL from the predicted lateral acceleration GRLM.
Graph corresponding to the map used to calculate M, ΔPFRM, ΔPRLM, ΔPRRM, FIG. 13 shows predicted lateral acceleration G
The graph corresponding to the map used for calculating the feedforward gain k1 and the feedback gains k2, k3 based on the difference between the RLM and the actual lateral acceleration GRL, FIG. 14 is based on the vehicle speed V and the vehicle height control mode. A graph corresponding to the map used to calculate the target heave amount XHM,
FIG. 15 is a graph corresponding to the map used to calculate the target pitch amount XPM based on the actual longitudinal acceleration GFR.
FIG. 16 is a graph corresponding to the map used to calculate the target roll amount XRM based on the actual lateral acceleration GRL, No. 17
The figure is a graph corresponding to the map used to calculate the target change rate PM of the pitch amount based on the actual longitudinal acceleration change rate FR, and Fig. 18 shows the roll amount based on the actual lateral acceleration change rate RL. The graph corresponding to the map used to calculate the target rate of change RM, FIG. 19 shows the pressure P1 in the high pressure reservoir and the pressure in the main gas chamber that receives air from the reservoir.
A graph corresponding to the map used to calculate the coefficients aF / φ and aR / φ based on the ratio P1 / P2 with P2. Fig. 20 shows the pressure P2 in the main gas chamber and air from the main gas chamber. Coefficients bF / φ, bR based on the ratio P2 / P3 to the pressure P3 in the low pressure reservoir
21 is a graph corresponding to the map used to calculate / φ, and FIG. 21 is a graph corresponding to the map used to calculate the output duty based on the actual valve opening times TU and TD. M2 …… Fluid actuator, M4 …… Running state detection means, M5
...... Attitude target change amount setting means, M6 …… Abnormal control means, 1FL, 1FR, 1RL, 1RR …… Suspension, 2FL, 2F
R, 2RL, 2RR ... Gas spring, 26, 30 ... High-pressure reservoir opening / closing valve, 34, 36, 50, 52, 54, 56, 70, 72 ... High pressure sensor, 42 to 48 ... For air supply Open / close valve, 58 ~ 66 ... Exhaust open / close valve, 8
0 to 86 …… vehicle height sensor, 90 …… steering angle sensor, 92 …… acceleration sensor, 93 …… vehicle speed sensor, 94 …… door switch, 95…
… Neutral switch, 96 …… Throttle opening sensor,
100: Electronic control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Yonekawa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Osamu Takeda 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. ( 72) Inventor Shunichi Doi 1 41st Yokomichi, Nagakute-cho, Aichi-gun, Nagakute Town, Toyota Central Research Institute Co., Ltd. (56) References JP-A-1-95926 (JP, A) Actual Development Sho 60-69709 ( JP, U) JP 61-10321 (JP, B2)

Claims (1)

[Claims] 1. A fluid actuator provided corresponding to each wheel for increasing and decreasing the vehicle height of a corresponding portion by supplying and discharging a working fluid, and a fluid supply and discharge means for supplying and discharging the working fluid to and from the fluid actuator. A running state detecting means for detecting or estimating the acceleration of the vehicle body; a target posture change amount setting means for setting a target posture change amount of the vehicle body according to the acceleration estimated or detected by the running state detecting means; Attitude change amount detecting means for detecting or estimating the attitude change amount of the vehicle body, and the attitude change amount of the vehicle body matches the target attitude change amount based on the deviation between the vehicle body attitude change amount and the target attitude change amount. In an electronically controlled suspension device having control means for controlling the fluid supply / discharge means, the control means is detected or estimated by the running state detection means. When the magnitude of acceleration exceeds a predetermined value, the target posture change amount is set so that the ratio of the target posture change amount to the acceleration is higher than that when the magnitude of acceleration is equal to or smaller than the predetermined value. An electronically controlled suspension device characterized by the above.