JPH03239618A - Electronic control suspension device - Google Patents

Abstract

PURPOSE:To prevent an abrupt action change by setting a variation amount so that, when estimated or detected acceleration is more than a predetermined value, a target posture variation ratio to acceleration becomes higher than in the case where the acceleration is less than the perdetermined value, in an electronic control suspension device of an automobile and the like. CONSTITUTION:A running state detecting means M4 detects or estimates acceler ation of a vehicle body to input into a control means M5. The control means M5 determines a target posture variation amount in accordance with the acceler ation, and controls a hydraulic actuator M2 via a fluid supplying/discharging means M3 to adjust a car height. In this case, when the acceleration is more than the predetermined value, a target posture variation amount is determined so that a ratio thereof to the acceleration becomes higher than in the case of the acceleration being less than the predetermined value. According to this constitution, roll rigidity and pitch rigidity are reduced in the case of the acceler ation exceeding the predetermined value and a driver can acknowledge the state is approaching the limit running state so that an abrupt action change is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a suspension for a vehicle such as an automobile, and more particularly to an electronically controlled suspension device that controls the attitude of a vehicle body.

[Prior Art] Various devices have been proposed in the past for controlling the posture of a vehicle such as an automobile in order to improve the ride comfort, handling stability, etc. of the vehicle. For example, as described in Japanese Unexamined Patent Publication No. 193907/1984, the attitude of the vehicle body changes according to a 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) of the unsprung area and the unsprung floor of the vehicle is calculated according to this attitude change response amount. Suspension devices configured to control actuators provided in correspondence with wheels have already been proposed.

According to such a suspension device, the target attitude change amount of the vehicle body is set in accordance with the acceleration of the vehicle body, so the attitude of the vehicle body is controlled in accordance with the acceleration of the vehicle body, and therefore the vehicle body changes even when the vehicle turns or accelerates or decelerates. can 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 Publication No. 61-193907, even when extremely rapid turning or acceleration/deceleration is performed, the If attitude control is performed that does not significantly change the vehicle's attitude, the driver will not be able to recognize even if the vehicle's turning, acceleration and deceleration conditions reach the limit driving conditions. When these conditions exceed the limit driving conditions, there is a risk that sudden changes in vehicle behavior such as drift may occur.

In view of the above-mentioned problems with conventional electronically controlled suspension devices, the present invention makes it possible to maintain a stable posture of the vehicle body when the acceleration of the vehicle body is relatively low, and to prevent the vehicle from turning or accelerating. It is an object of the present invention to provide an electronically controlled suspension device which is improved so that when deceleration conditions reach the limit running conditions, the driver can accurately recognize this by a change in the attitude of the vehicle body.

[Means for Solving the Problems] According to the present invention, as illustrated in the basic configuration diagram of FIG. a fluid actuator M2 that increases/decreases the vehicle height of a corresponding portion by adjusting the height of the vehicle; and a fluid supply/discharge means M3 that supplies/discharges working fluid to/from the fluid actuator.
and a driving state detecting means M4 for detecting or estimating the acceleration of the vehicle body, and a target attitude change amount of the vehicle body is set according to the acceleration estimated or detected by the driving state detecting means, and a target attitude change amount of the vehicle body is set. control means M5 for controlling the fluid supply and discharge means so as to match the target attitude change amount;
In the electronically controlled suspension device having the above, when the acceleration detected or estimated by the traveling state detection means exceeds a predetermined value, the control means sets a target attitude relative to the acceleration compared to when the acceleration is less than the predetermined value. This is achieved by an electronically controlled suspension system that is configured to set a target posture change amount so that the ratio of the change amounts becomes high.

[Operation of the Invention] According to the configuration as described above, when the acceleration estimated or detected by the driving state detection means is less than or equal to a predetermined value, the control means sets the target attitude change amount of the vehicle body according to the acceleration;
The target attitude change amount is set so that when the acceleration exceeds a predetermined value, the ratio of the target attitude change amount to the acceleration is higher than when the acceleration is less than the predetermined value.

Therefore, when the acceleration is below a predetermined value, the vehicle body maintains a stable posture even when the vehicle turns or accelerates or decelerates, and when the acceleration exceeds a predetermined value, the roll stiffness of the vehicle increases compared to when the acceleration is below the predetermined value. By reducing the pitch and pitch stiffness, a relatively large change in the posture of the vehicle body occurs, which allows the driver to recognize that the conditions for turning and acceleration/deceleration of the vehicle are approaching the limit driving conditions. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

[Embodiment] FIG. 2 is a schematic configuration diagram showing one embodiment of an electronically controlled suspension device according to the present invention, and FIG. 3 is an air circuit diagram of the embodiment shown in FIG. 1.

The electronically controlled suspension device of the illustrated embodiment includes a left front wheel, a right front wheel, a left rear wheel, and a left front wheel connected to an air circuit AC.
Suspension IFL for the right rear wheel.

These suspensions have gas springs 2FL and 2FR, respectively.

2RL, 2RR and shock absorber 3FL.

3FR, 3RL, and 3RR are provided.

As shown in FIG. 3, a gas spring 2FL.

2FR, 2RL, and 2RR are the main gas chambers 4FL and 4, respectively.
FR, 4RL, 4RR and auxiliary gas chamber 5FL.

5FR, 5RL, and 5RR, and a part of the main gas chamber is formed by diaphragms 6FL, 6FR, 6RL, and 6RR, respectively, so the main gas chambers 4FL, 4FR, and 4
By supplying and discharging air to RL and 4RR, the vehicle height of the corresponding parts can be adjusted.
Each suspension thus constitutes a fluid actuator M2 in FIG.

Each of the gas springs 2FL, 2FR, 2RL, and 2RR is an actuator 7FL for changing the spring constant.

7FR, 7RL, and 7RR, and by driving these actuators, the communication between the corresponding main gas chamber and the auxiliary gas chamber or the degree of communication thereof is switched and controlled,
This allows the spring constant to be changed to three levels: "low,""medium," and "high." In addition, the shock absorbers 3FL, 3FR, 3RL, and 3RR have actuators 8FL, 8FR, and 8 for damping force switching, respectively.
R.L.

8RR, and by driving these actuators, the effective passage cross-sectional area of the orifices (not shown) provided in the pistons 3a, 3b, 3c, and 3d is controlled, and thereby the cylinder 3e.

By changing the flow resistance when the oil in 3f, 3g, and 3h flows through the orifice, the damping force can be set to "low" or
It is possible to change to three levels: "medium" and "high."

The air circuit AC is provided with a compressor 10 as a 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 valve 16 via a check valve 12 that prevents backflow. A desiccant such as silica gel is enclosed within the air dryer 14 to remove moisture from the compressed air passing through it. The air dryer 14 is connected to a supply on-off valve 22 and a connection on-off valve 24 via a fixed throttle 18 and a check valve 20 that prevents backflow.

The on-off valve 22 is connected to a relief valve 25 set at 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 to a high-pressure reservoir 28 for the front wheels via an on-off valve 30 for the high-pressure reservoir. It is connected to a high pressure reservoir 32 for the wheels. These reservoirs 28 and 32 are equipped with pressure sensors 34 and 36 that detect the pressure of the air in the corresponding reservoirs, respectively, and a relief valve 3 that is set to a predetermined pressure.
8 and 40 are provided. Also, supply on-off valve 2
2 are connected to main gas chambers 4FL, 4FR, 4RL, and 4RR via air supply on-off valves 42, 44, 46, and 48, respectively. Main gas chamber 4FL.

Pressure sensors 5, 0.52, 54, and 56 are connected to 4FR, 4RL, and 4RR, respectively, to detect the internal air pressure.

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 exhaust valves 58 and 6o, respectively. Similarly, the main gas chamber 4 for the left and right rear wheels.
RL and 4RR are exhaust valves 64 and 66, respectively.
It is connected to a low pressure reservoir 68 for the rear wheels via.

The low pressure reservoirs 62 and 68 for the front and rear wheels are always connected to each other. Further, pressure sensors 70 and 72 are connected to these reservoirs 62 and 68, respectively, to detect the pressure of the air in the corresponding reservoirs, and in particular, the reservoir 62 is provided with a relief valve 74 set to a predetermined pressure. ing. Furthermore, the reservoirs 62 and 68 are connected to the connection on-off valve 24, and are also connected to the suction side of the compressor 10 via the suction on-off valve 76. A check valve 78 is provided on the suction side of the compressor 10 to allow only air to flow from the atmosphere to the compressor.

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

Note that the air circuit AC may be configured as a completely closed circuit by omitting the check valve 78, and in that case, air or another gas such as nitrogen gas may be sealed in the air circuit. In addition, in the illustrated embodiment, on-off valves 16, 22, 24
．． 26.30.42 to 48.58 to 66.76 are normally closed on-off valves, but these on-off valves may be normally open on-off valves. Furthermore, in the illustrated embodiment, separate high-pressure reservoirs 28.32 and low-pressure reservoirs 62,68 are provided for the front and rear wheels; however, one common reservoir for the front and rear wheels is provided. A high pressure reservoir and a low pressure reservoir may be provided.

As shown in Figure 2, the left front wheel, right front wheel, left rear wheel,
Vehicle height sensors 80, 82, 84, and 86 are provided at positions corresponding to the right rear wheel to detect the vehicle heights of the respective corresponding parts. These vehicle height sensors output a vehicle height signal as a deviation of the actual vehicle height from a predetermined reference vehicle height. Additionally, a steering angle sensor 90 detects the steering angle of the steering wheel 88. An acceleration sensor 92 that detects the acceleration of the vehicle body in the lateral and longitudinal directions; a vehicle speed sensor 93 that detects the vehicle speed from the rotational speed of the output shaft of the transmission (not shown); A door switch 94 detects the state, and a neutral switch 95 detects that the shift position of the transmission is neutral.
, a throttle opening sensor 96 (not shown) for detecting the opening of a throttle valve that controls the intake air amount of the internal combustion engine is provided. It is also operated by the vehicle occupant to set the target vehicle height to "high" or "high" depending on the vehicle speed.
A vehicle height high switch 97 and a vehicle height low switch 98 for instructing "medium" and "medium" or "low" are provided.

Note that the steering angle sensor 90, acceleration sensor 92, and vehicle speed sensor 9
3 constitutes the running state detection means M4 shown in FIG.

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

The above air circuit AC and each suspension 1FL, IF
R, IRL, and IRR are controlled by an electronic control circuit 100. As shown in FIG. 4, an electronic control circuit 100
is configured with a well-known CPU 102, ROM 104, and RAM 106 as central elements of a logical operation circuit, and these elements are connected to an actuator drive circuit 108 and a valve drive circuit 1.
101, a sensor input circuit 112, a level input circuit 114, and a common bus 116.

The CPU 102 uses pressure sensors 34, 36, 50 to 56.
70.72, vehicle height sensor 80-86, steering angle sensor 90
, the acceleration sensor 92, the vehicle speed sensor 93, and the throttle opening sensor 96 are input through the sensor input circuit 112, and the door switch 94 and the neutral switch 9
5. Signals from the vehicle height high switch 97 and vehicle height low switch 98 are input manually via the level input circuit 114. In addition, the CPU 102 receives these signals and the RO
Based on the data in M104 and RAM 106, the compressor motor 9 and spring constant switching actuators 7FL, 7FR, 7RL are activated via the actuator drive circuit 108.
, 7RR, damping force switching actuator 8FL, 8F
A drive signal is output to R, 8RL, and 8RR, and also passes through the valve drive circuit 110 to the exhaust on-off valve 16, the supply on-off valve 22,
Connection on/off valve 24, high pressure reservoir on/off valves 26 and 30
, air supply on-off valves 42-48, exhaust on-off valves 58-66,
A drive signal is output to the intake on-off valve 76, thereby controlling each suspension IFL, IFR, IRL, and IRR.

Note that the ROMI 04 stores maps corresponding to the graphs shown in FIGS. 10 to 21, as described later.

Next, various processes performed in the electronic control circuit 100 described above will be explained 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 flowchart showing an example of control of the suspension device according to the present invention, and FIGS.
The figures are flowcharts showing details of the processing carried out in steps 200, 400, 500, and 600 of the flowchart shown in FIG. 5, respectively.

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

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

In the next step 2'OO, suspension IFLSIFR is performed to deal with the roll of the vehicle body.

IRL, IRR gas springs 2FL, 2FR, 2RL, 2
Among the air supply/discharge control for the RR, the calculation process of the feedforward control is executed according to the flowchart shown in FIG. This phytoforward control estimates the lateral acceleration GRLM of the vehicle body from the vehicle speed and steering angle, and activates the gas spring 2FL according to the estimated lateral acceleration GRLM.

The air pressure of 2FR, 2RL, and 2RR is adjusted to prevent or suppress vehicle body roll.

In the next step 400, arithmetic processing for feedback control is executed according to the flowchart shown in FIG. 7, which is part of the air supply/discharge control for the gas spring. This feedback control attempts to stabilize the attitude of the vehicle body by adjusting the air pressure of the gas spring based on the actual acceleration of the vehicle body.

In the next step 5'00, the total pressure control amount for each suspension, ie, the sum of the pressure control amounts calculated in steps 200 and 400, is calculated (see FIG. 8).

In the next step 600, the high pressure reservoir on-off valve 26 is operated based on the total pressure control amount calculated in step 500.
and 30. Air supply on-off valves 42 to 48, exhaust on-off valve 58
-66, the drive duty for opening and closing the necessary on-off valves among the suction on-off valves 76 is calculated (see FIG. 9).

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

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

First, in step 210, filtering processing is performed on each signal. In other words, the data read this time is X (
n), and the value after the previous filtering process is Y (n
-1), and the filtering constant is Ir (-1 to 25
6), the output Y (n
) is expressed by the following formula.

56 Note that this process is a process for canceling out noise components of detected data and averaging fluctuations of data having a frequency equal to or higher than a predetermined value.

In the next step 220, the door switch 94 of the vehicle is
Based on the signal from the neutral switch 95, it is determined whether all the doors are closed, and in step 230, it is determined whether the transmission is in the neutral state based on the signal from the neutral switch 95. In step 240, it is determined whether the throttle valve is fully closed based on the signal from the throttle opening sensor 96, and in step 25
0, among the suspension control on-off valves, especially the high-pressure reservoir on-off valves 26 and 30, and the air supply on-off valves 42-
48. It is determined whether the vehicle height control for resuspension is being performed by the exhaust on-off valves 58, 66, and in step 260, based on the signal from the vehicle speed sensor 93, it is determined that the vehicle speed V is below a predetermined value Vo. A determination is made as to whether or not this is the case.

Thus, in steps 220, 230, 240, and 260, factors that change the attitude of the vehicle body (for example, the opening and closing of doors for passengers to get on and off, the shift position of the transmission that indicates the state of transmission of driving force to the tires, and the internal combustion The amount of intake air corresponding to the output of the engine, and the vehicle speed, which is one of the variables indicating the running state of the vehicle, are determined, and in step 250, air supply and exhaust is performed to adjust the pressure of the gas spring. A determination is made as to whether or not.

If all of the determinations in steps 220 to 260 are affirmative, the attitude of the vehicle body is in a stable state, and the pressures of the gas springs 2FL, 2FR, 2RL, and 2RR are not subject to large fluctuations. Since it can be estimated that the pressures are stable, in the next step 270, the pressures detected by the pressure sensors 50 to 56 are set as the reference pressures PFLA, PFRA 5PRLA 5PRRA, and are stored in the RAM 106.

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

If a negative determination is made in any of steps 220 to 260, step 270 is not executed, and therefore the reference pressures PFLA, PRLA, PRRA
is not updated; on the contrary, as long as all conditions 220 to 260 are satisfied, the reference pressure is always updated.

After step 270 is completed or steps 220-26
If a negative determination is made in any of the above, in the next step 280, the estimated lateral acceleration GRL of the vehicle body is calculated from the vehicle speed V and the steering angle θ based on a map corresponding to the graph shown in FIG. Calculated.

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

In the graphs of Figures 10 and 11, only two and eight broken lines are shown, respectively, 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, predicted lateral acceleration GRLM is calculated according to the following equation.

GRLM=m-GRL+h-GRL where m and h are constants, and each is a value that may be obtained, for example, experimentally in order to predict the roll of the vehicle body.

In the next step 310, each gas spring 2FL,
Predicted pressure change amounts ΔPFLM, ΔPF when the pressures of 2FR, 2RL, and 2RR are estimated to change due to lateral acceleration
RM, ΔPRLM, and ΔPRRM are calculated.

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

ΔPFLM -a ・GRLM ΔPFRM = -a -GRLM Δ PRLM -b -GRLM ΔPI? RM--b ・G RLM here a and b
are coefficients for correcting variations in suspension stiffness characteristics, and are expressed as follows.

Here, W is the sprung mass, H is the height of the center of gravity, and T
r and Tr are the treads of the front and rear wheels, respectively;
Rr and Rr are the arm ratios of the front and rear wheels, respectively, Af' and A' are the pressure-receiving areas of the pistons of the front and rear suspensions, respectively, L is the wheelbase, and Lr is the ratio between the rear wheels and the center of gravity. is the distance between K
f is an arbitrary constant set in the range of (L/Lr)>Kf'al, 0. This Kf represents the load sharing ratio of the front wheels, and by changing this value, the steering characteristics of the vehicle can be arbitrarily set. For example, Kf or 1.
When it is 0, the shared load ratio of the front wheels is 50%.

Furthermore, as shown in Fig. 12, in order to prevent repeated minute adjustments due to fluctuations in calculated values, detection errors, noise, etc., -i≦G RLM≦i (i is a positive constant), the predicted pressure change amount ΔPFLM, ΔP
A dead zone is provided in which FRM, ΔPRLM, and ΔP RRM are set to zero.

In the next step 320, steps 270 and 31
Based on the calculation result at 0, the target pressure PF of each gas spring
LM, PPRM, PI? LM and PRRM are calculated according to the following formula.

P FLM - ΔP PLM + P FLAP FRM
−ΔP PRM + P FRAP RLM■ΔP R
LM+PI? LAP RRM - ΔP RRM +
In step 330 following PRRA, the deviations EFL, EPR, ERL, and ERR of each pressure are calculated according to the following formulas.

EPL-PFLM-PFL EFR-PFl? M-PFR EI? L-Pl? LM-PRL El? I? -PRRM-PRR In the above formula, PFL, PFRSPRL, PRR
are the pressures detected by the pressure sensors 50 to 56 provided in the main gas chambers 4FL, 4FR, 4RL, and 4RR, respectively, and are the values after filtering processing.

In the next step 340, the gain kl of the feedforward control calculation executed in the next step 350 is calculated as shown in FIG. Based on the map corresponding to the graph indicated by the broken line, the estimated JFI lateral acceleration GI?
It is calculated according to the difference between LH and actual lateral acceleration GRL.

In this case, as shown in FIG. 13, the absolute value GRLM
- When GRLI is less than or equal to q, 1 is 0, and when it is greater than or equal to 0, 1 is T, and between these, kl gradually increases as the absolute value IGRLM-Grll increases. . Therefore, the larger 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 of each suspension.

In the next step 350, the deviations ERL, EPR, ERL of each pressure calculated in step 330 are calculated.

1 to ERR and the gain calculated in step 340.
Based on the formula below, each suspension I RL,
Pressure control amounts CIFL and CIPR by feedforward for I FR, I RL, and I RR
, CII? L.

CIRR is calculated.

CIPL-kl ・EPL CIFI? -kl -EFR CIRL-kl ・ERL CIRR-kl ・ERR FIG. 7 is a flowchart showing the feedback control calculation process executed in step 400.

First, in step 410, the vehicle heights XFL, XFI? of the parts corresponding to the left front wheel, right front wheel, left rear wheel, and right rear wheel detected by the vehicle height sensors 80 to 86 are determined. , XRL, XRI
? Based on the formula below, the heap amount (vertical displacement amount) XH, pitch amount xp, roll JIXR1 twist amount X of the car body
ν is calculated.

X) (-(XFR+XFL) + (XRR+XRL)
XP −(XPR+XPL) −(XRR+XRL)X
R-(XPR-XFL) + (XRR-XRL)XW
-(XFR-XFL) -(Xl?R-Xl?L) In the next step 420, each mode quantity XH, XP, XR calculated in step 410 is calculated.

Based on XW, the deviation EH of each mode quantity according to the following formula,
EP, ERSEV.

EH-XHM-XH EP-XPM-XP ER-XRM-XI? EV-XWM-XW In the above formula, XHM is the target heap amount, and the mode (H-A
(UTO) or the mode (N-AUTO) set by the vehicle height low switch 98, based on a map corresponding to the graph shown in FIG. Also XPM and XR
M is a target pitch amount and a target roll amount, respectively, and each is an actual lateral acceleration GFR detected by the acceleration sensor 92.

and actual lateral acceleration CI? Calculations are made from L based on maps corresponding to the graphs shown in FIGS. 15 and 16.

Further, XWM is a target twist amount, and may be 0.

In the next step 430, each mode @XH.

XP, XR, XW (7) Differential value XHSXPSXR
Based on SXν, the deviations mu, *p, mR, *ν of the rate of change of each mode quantity are calculated according to the following formula.

Note that xHSxp, xv<, and xv are XH and XP, respectively.
, XR, and XW during a predetermined time period.

Here, the statement IIM is the target change rate of the heap amount, and may be 0. XPM and X12M have a target change rate of pitch amount and a target change rate of roll amount, respectively, and correspond to the graphs shown in FIGS. 17 and 18 from the change rate of longitudinal acceleration 6PR and the change rate of lateral acceleration GRL, respectively. Calculated based on the map. Further, X0M is a target rate of change in the twist amount, and may be 0.

As shown in FIGS. 15 to 18, the target pitch jl f'rr2 (negative constant) and the first predetermined value g('rf'l (positive constant) and the second predetermined value g"
Between rf2 (positive constant), is the actual longitudinal acceleration GFI? are each greater than or equal to the first predetermined value gf'rr1,
The ratio of the target pitch amount First predetermined value g rllll
(negative constant) and the second predetermined value grl12 (negative constant), and between the first predetermined value grlrl (positive constant) and the second predetermined value grlr2 (positive constant). In this case, the actual lateral acceleration GRL is the first predetermined value gr! I
The target roll ffi X R for the actual lateral acceleration GRL is greater than or equal to
The ratio of M is set to be high.

Similarly, the target change rate XPM of the pitch amount and the target change rate XRM of the roll amount are respectively the first predetermined value gpmrt (negative constant), grmll (negative constant) and the second predetermined value g.
between pmr2 (negative constant) and grIl112 (negative constant) and the first predetermined value gpIIlrl (positive constant),
gr+arl (positive constant) and second predetermined value g pmr2
(positive constant) and grmr2 (positive constant), the pitch amount target change condolence PM and the roll amount target change condolence RM are respectively the first predetermined value g pIIlr
tSg rm11 or more, first predetermined value g pmf'L
Compared to the case where g rIlr1 or less, the ratio of the target change rate XPH of the pitch amount to the actual change rate GFR of the longitudinal acceleration, and the ratio of the target change rate XRM of the roll amount to the actual change rate 6RL of the lateral acceleration are higher. It is set to be.

In addition, the target pitch amount XPM is the actual longitudinal acceleration GF of the vehicle body.
As R becomes smaller than the second predetermined value g frr2 or larger than the second predetermined value gf''rr2, its absolute value gradually decreases, and the third predetermined value g
It is set to be 0 at frr3, g frf3, and the vehicle body with target roll amount XRM also has the actual lateral acceleration G.
As RL becomes smaller than the second predetermined value grl12 or larger than the second predetermined value grlr2, its absolute value gradually decreases, and reaches 0 at the third predetermined values grl13 and grlr3, respectively. It is set to be.

Similarly, the pitch amount target change condolence letter PM and the roll amount target change condolence message RM are respectively set to second predetermined values g pmr2, g
Their absolute values gradually decrease as they become smaller than ra+r2 or as they become larger than the second predetermined values gpmf'2, grn'2, and the third predetermined values gpmr3 and gplf'3, grmr3 and gr, respectively.
It is set to be o in mf3.

Furthermore, in the illustrated embodiment, a third predetermined value gf'r "3
and grl13 are set to a value substantially equal to the value of an abnormal signal that is manually input to the electronic control circuit 100 in the event that a wire harness (not shown in the diagram) that transmits the output signal of the acceleration sensor 92 is disconnected. , third predetermined value g fr
f3 and grlf'3 are set to values substantially equal to the value of an abnormality signal input to the electronic control circuit in the event of a short circuit in the wire harness. Similarly, the third predetermined values gpmr3 and grll13 are the rate of change of abnormal acceleration as an instantaneous value calculated based on the abnormal value of acceleration input to the electronic control circuit when the wire harness is disconnected, or It is set to a value corresponding to the abnormal rate of change in acceleration that deviates from the control range due to an abnormality in the RAM 106, etc.
The third predetermined values gpfflf'3 and grmr3 are the rate of change of abnormal acceleration as an instantaneous value calculated based on the abnormal value of acceleration input to the electronic control circuit when the wire harness is disconnected, etc. Alternatively, it is set to a value corresponding to an abnormal rate of change in acceleration that deviates from the control range due to an abnormality in the RAM 106 or the like.

In step 440, which is performed after step 430, the feedback gain is set to 2H and 2P in the calculation formula of the calculation executed in the next step 450 in order to convert the deviation of each mode into a control amount. , k2R, k2W(
k2) and 3H, 3PSk3R, and 3W
(generally referred to as k3) is calculated based on the map corresponding to the graph shown by the solid line in FIG. 13 according to the difference between the predicted lateral acceleration GRL)4 and the actual lateral acceleration GRL.

In this case, as shown in FIG. 13, the absolute value GRLM
-GI? When Ll is less than or equal to q, 2 and 3 are T, and when it is greater than or equal to 0, 2 and 3 are t, and between these, the absolute value]GRLM-Grll increases. 2 and 3 gradually decrease. Therefore, the smaller the difference between the predicted lateral acceleration GRLM and the actual lateral acceleration GRL, the higher the degree of contribution of the feedback control to the control of each suspension.

In the next step 450, the deviations EH and EP of each mode quantity calculated in step 420 are calculated.

ERSEV and the deviation of the rate of change of each mode quantity calculated in step 430 E) From ISEP and ERSEW, feedback of each mode according to the following formula! D.H., D.P.
, DRSDW MK is calculated.

DH-k2H-EH+ k3H◆ 4HDP to EH+
-k2P-EP + k3P-EP + k4
PDR- to 2R-ER+ to 3R-ER+ to 4RDW
-2W-EV +3W-ew +4W Here 4HSk4P and k4RSk4W are constants.

In the next step 460, the feedback of each mode calculated in step 450 jlDII, DP,
Based on DRSDW, feedback controls ff1DFL, DFR, and DRLSDRR for each suspension IFL, IFR, IRL, and IRR are calculated according to the following equations.

DFL-1/4 (kOH-DH+ 2 kOP-Lr
-DP-kOR-DR-kOW-DW) DFR-1/4(kOH-DH+2 kOP-Lf -
DP+ kOR-DR+ kOW-DW) DRL-1/4(k OH-DH-2k OP-(1-
L f)-DP-kOR-DR+kOW-DW)D
RR-1/4(k OH-D H-2,k OP・(1
-Lf')-DP 10kOR-DR-kOW-DW):
: nik OH, k OP, k OR, k OWi
, is a constant coefficient, and Lf is a distribution coefficient between the front and rear wheels taking into account the position of the center of gravity of the vehicle body within the wheelbase.

In the next step 470, the feedback control ff1DFLSDFR,D calculated in step 460 is
Based on RLSDRR, pressure control amount C2FL SC2'FR5C2RLS by feedback according to the following formula
C2RR is calculated.

C2FL -PFL-a 2PL -DFLC2FR=
PFR・a2FR・DrR C2RL -PRL・a 2RL 11 DRL
C2RR-PRRlla In the 2RR/DRRRR internal formula, PFLSPFR and PRLSPRR are main gas chamber 4 FL
, 4 FR, 4 RL, and 4 RR are pressures detected by pressure sensors 50 to 56 provided in 4 RR, and are filtered values. Also a2PL.

a2FR5a2RL % a2RR is a constant coefficient.

In step 510 shown in FIG.
Pressure control amount CIFL by feedforward calculated in step 50, CIFR5CIRL 5CIRR and pressure control jl by feedback calculated in step 470 C2FL%C2FR, C2RL, C2
Based on RR, the total pressure control amount CPL, CPI? for each suspension according to the following formula: , C.R.L.

CRI? is calculated.

CFL -CIFL + C2PL CFR-CIPR+ C2PR CRL -CIRL + C2RL CRR-CIRR+ C2RR Figure 9 shows step 6 of the flowchart shown in Figure 5.
3 is a flowchart showing the calculation process of the on-off valve control amount performed in 00.

In step 610, the high-pressure reservoir on-off valve is operated to adjust the pressure in the main gas chambers 4FL, 4PL, 4RL, and 4RR based on the total pressure control amounts CFL, CFR, and CRLSCRR calculated in step 510. 26 and 3
0°Air supply on-off valves 42-48 or exhaust air on-off valves 58-6
6 valve opening time (time maintained in open state) TFL,
TFR, TRL%TRR are calculated according to the following formula.

On-off valve for pressure increase, ie, on-off valve for high pressure reservoir 26.
30 and air supply on/off valves 42 to 48 TPL-(aF
/φ) (CFL/ P PH) TFR-(aF/
φ) (CFR/P PH)TRL-(aR/φ
) (CRL/PRH)TRR-(aR/φ)
(, CRR/P RH) For pressure reduction on-off valves, that is, exhaust on-off valves 58 to 66, TFL-(bF/φ) (CFL/P Fl+)
TFR-(bF/<6) (CFI?/Prl+
)Tl? L-(bR/φ) (CRL/PRH)T
RR-(bR/φ) (CRI?/PRH) In each of the above equations, aF/φ and aR/φ are the pressure PL in the high pressure reservoir (-PFH or PRH) and the air supply from the reservoir. Based on the ratio PL /P2 of the received pressure to the corresponding pressure P2 in the main gas chamber, calculation is made based on a map corresponding to the graph shown in FIG. Furthermore, bP/φ and bR/φ are the ratio P2 of the pressure P2 in the corresponding main gas chamber and the pressure P3 in the low pressure rehearsal chamber that receives the air discharged from the main gas chamber.
/P3 calculates based on the map corresponding to the graph shown in FIG. 20.

In the next step 620, based on the valve opening time calculated in step 610, the time during which the on-off valve is actually opened (actual valve opening time) TFLU XTFR is determined according to the following formula.
LI, TI? Lji, TRRLI (in case of pressure increase)
and TFLD, TFRD, TRLD, TR
RD (in case of pressure drop) is calculated.

In the case of an on-off valve for pressure increase T FLU-αF・TFL+βPL T PRU-αF-TFR+βFR TRLU=αR-TRL+βRL T RRU-αR-TRR+βI? R In the case of an on-off valve for pressure reduction T PLD-γF-TFL+δFL T PI? D-γF-TPI? +δFl? T RLD-
γR−TRL+δI? L T RRD-γR-TRR+δI? R In each of the above formulas, αF17F, αR1γR1βFL,
βFR, βRL, βRR, δFL1 δPR, δRL,
δ1? l? is a fixed constant.

In the next step 630, the actual valve opening times TFLtl, TFR of each on-off valve calculated in step 620 are calculated.
U%TRLtl, TRRlj (collectively referred to as TU)
Or TFLD, TFRD 5TRLD STI? R
D (generally referred to as TD) guard processing is performed. This process is performed to prevent the on-off valve from being repeatedly opened and closed, thereby protecting the on-off valve. For example, as shown in FIG. 21, if the actual valve opening time TU or TD is calculated such that the duty is less than 30%, the actual valve opening time TLI STD is set to 0 and the duty is less than 80%. Actual valve opening time TU or T exceeding
When D is calculated, the actual valve opening times TU and TD are fixedly set to the valve opening time corresponding to a duty of 80%.

In the next step 640, the driving duty representing the opening time of the on-off valves 26.30, 42-48.58-62 is determined by the actual valve opening time TU or TD after the guard processing in step 630. is set.

Thus, according to the illustrated embodiment, the target pitch ffi
M, the target change rate XPM of the pitch amount and the target change rate XRM of the roll amount, which are the target change rates of the vehicle body posture, are changed as the acceleration increases when the value of the acceleration signal from the acceleration sensor 92 exceeds the first predetermined value. Increases relatively rapidly.

Therefore, when the acceleration of the vehicle body exceeds the first predetermined value, the roll stiffness and pitch stiffness of the vehicle are reduced compared to when the acceleration is below the first predetermined value, resulting in a relatively large attitude change of the vehicle body. Therefore, the driver can reliably recognize that the turning and acceleration conditions of the vehicle have reached the limit driving conditions.

Further, according to the illustrated embodiment, the target pitch amount XPM, the roll amount XRM, the target change rate XPM of the pitch amount, and the target change rate XRM of the roll amount are such that the value of the acceleration signal from the acceleration sensor 92 is the second predetermined value. When the value of the acceleration signal becomes an abnormal value between the third predetermined value and the third predetermined value, the absolute value of each target change amount is corrected to be reduced to a lower value, and when the value of the acceleration signal becomes an abnormal value of the third predetermined value or more. Each target change amount is set to zero. Therefore, even if the value of the acceleration signal from the acceleration sensor 92 becomes an abnormal value, the vehicle body posture control itself continues, and as a result, the vehicle body posture control based on the abnormal value is avoided, and the vehicle body posture greatly deteriorates. This is prevented, and the vehicle body is corrected to be reduced or controlled to a posture based on the target change amount set to 0 (for example, a posture parallel to the road surface).

Furthermore, since the first to third predetermined values are set as described above, the slope between the first predetermined value and the second predetermined value as seen in FIGS. 15 to 18 is set to a steep slope. This allows the driver to reliably recognize that the turning and acceleration/deceleration conditions of the vehicle have approached the limit driving conditions.

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

[Effects of the Invention] As is clear from the above description, according to the present invention, when the acceleration estimated or detected by the driving state detection means is less than or equal to a predetermined value, the control means determines the target attitude change amount of the vehicle body according to the acceleration. The target attitude change amount is set so that when the acceleration exceeds a predetermined value, the ratio of the target attitude change amount to the acceleration is higher than when the acceleration is less than the predetermined value.

Therefore, when the acceleration is less than a predetermined value, the vehicle body maintains a stable posture even when turning or accelerating or decelerating, and when the acceleration exceeds a predetermined value, the vehicle becomes more stable than when the acceleration is less than the predetermined value. As the roll stiffness and pitch stiffness of the vehicle are reduced, a relatively large change in the attitude of the vehicle body occurs, so the driver cannot reliably recognize that the vehicle turning and acceleration/deceleration conditions are approaching the limit driving conditions. This makes it possible to prevent sudden changes in vehicle behavior such as drift.

[Brief explanation 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 configuration diagram showing one embodiment of an electronically controlled suspension device according to the present invention, and FIG. 3 is a diagram showing the basic configuration of an electronically controlled suspension device according to the present invention. An air circuit diagram of the embodiment, FIG. 4 is a block diagram showing the electrical system of the embodiment shown in FIGS. 1 and 2, and FIG. 5 is a block diagram showing the electronic control circuit shown in FIG. 4. FIG. 6 is a flowchart showing the feedforward calculation process performed in step 200 of the flowchart shown in FIG. 5, and FIG. 7 is a general flowchart of the control routine shown in FIG. FIG. 8 is a flowchart showing the calculation processing of the feedback control performed in step 400 of the flowchart, and FIG. 8 is a flowchart showing the calculation processing of the total pressure control amount performed in step 500 of the flowchart shown in FIG. , FIG. 9 is a flowchart showing the calculation processing of the on-off valve control amount performed in step 600 of the flowchart shown in FIG. 11 is a graph corresponding to a map used to calculate the rate of change G of estimated lateral acceleration from steering angular velocity θ and vehicle speed V. FIG. 12 is a graph corresponding to a map used to calculate predicted lateral acceleration. Predicted pressure change amount ΔPFLM, ΔPFRM, ΔPRLM, from CI21M,
The graph corresponding to the map used to calculate ΔP RRM, FIG. 13, calculates 2 and k3 for the feedforward gain kl and feedback gain based on the difference between the predicted lateral acceleration G RLM and the actual lateral acceleration GRL. The graph corresponding to the map used to calculate the target heap il
Graph corresponding to the map used to calculate HM, Figure 15 is a graph corresponding to the map used to calculate the target pitch ffi x PM based on the actual longitudinal acceleration GPH, Figure 16 is the actual graph. lateral acceleration GRL of
FIG. 17 is a graph corresponding to a map used to calculate the target roll amount XRM based on the actual longitudinal acceleration change rate 6PR. The first graph corresponds to
Figure 8 is a graph corresponding to a map used to calculate the target rate of change in roll amount XRM based on the actual rate of change in lateral acceleration 6RL, and Figure 19 is a graph corresponding to the map used to calculate the target rate of change in roll amount XRM based on the rate of change in actual lateral acceleration 6RL.
20th graph corresponding to a map used to calculate coefficients aF/φ and aR/φ based on the ratio Pi/P2 of the pressure P2 in the main gas chamber receiving air from the reservoir.
The figure corresponds to a map used to calculate the coefficients bF/φ and bR/φ based on the ratio P2/P3 of the pressure P2 in the main gas chamber and the pressure P3 in the low pressure reservoir receiving air from the main gas chamber. The graph shown in Figure 21 is the actual valve opening time TutS.
This is a graph corresponding to a map used to calculate output duty based on TD. M2...fluid actuator, M4...driving state detection means, M5...target posture change amount setting means, M6
...Abnormality control means, IFL, IFR, IRL, IR
R...Suspension, 2FL, 2FR, 2RL.

Claims (1)

[Claims] a fluid actuator that is provided corresponding to each wheel and increases or decreases the vehicle height of the corresponding part by supplying and discharging working fluid; a fluid supply and discharge means that supplies and discharges working fluid to and from the fluid actuator; a driving state detecting means for detecting or estimating the vehicle body, and a target attitude change amount of the vehicle body according to the acceleration estimated or detected by the driving state detecting means, and a target attitude change amount of the vehicle body is set to the target attitude change amount. In an electronically controlled suspension device having a control means for controlling the fluid supply/discharge means so as to match the fluid supply/discharge means,
When the acceleration detected or estimated by the running state detection means exceeds a predetermined value, the control means changes the target attitude so that the ratio of the target attitude change amount to the acceleration is higher than when the acceleration is below the predetermined value. An electronically controlled suspension device configured to set an amount.