JPH01160719A - Electronically controlled suspension unit - Google Patents

Abstract

PURPOSE:To improve control response in the suspension unit in the caption for controlling a vehicle position by damping a signal corresponding to a rolling or a pitching at a frequency higher than a predetermined one, so as to output it to a position control means when a detected operating condition is expected to generate an acceleration. CONSTITUTION:A rolling displacement quantity or a pitching displacement quantity is computed by a mode transformation means M4 according to the displacement of each wheel M1 which is detected by a displacement detection means M3, and a drive condition is computed by a drive condition detection means M6. An output signal from the mode transformation means M4 is damped at a predetermined frequency by a damping means M7, so as to be outputted to a position control means M5. At this time, when the drive condition detected by the drive condition detection means M6 generates an acceleration, the output signal from the mode transformation means M4 is damped at a frequency higher than the predetermined one so as to be outputted to the position control means M5. In this structure, the response to a position control at a rolling or a pitching can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electronically controlled suspension device that controls the displacement of a suspension to control the attitude of a vehicle.

[Prior Art] Various electronically controlled suspension devices have been proposed that control suspension displacement to improve ride comfort and handling stability. In these conventional devices, the displacement of each suspension of the vehicle is detected by a displacement detection sensor, etc.
From the detected displacement, each mode displacement amount representing the vehicle posture, such as vertical displacement amount, roll displacement amount, pitch displacement amount, and torsional displacement amount, is calculated, and the suspension is controlled based on the output signal corresponding to the calculated mode displacement amount. However, a device that controls the attitude of the vehicle is known (Tokusho 60-500662).
.

[Problem d to be solved by the invention] However, in such a conventional electronic side leg suspension device, when the attitude is controlled according to the amount of displacement in each mode, it is difficult to deal with attitude changes due to turning, braking, or acceleration. Although the response is good, due to the influence of high-frequency vibrations such as when driving on rough roads, if high-frequency vibrations are detected, the attitude control will always be delayed, resulting in problems with the response of the equipment, and the equipment may be prone to hunting. There was a problem that this could happen. Additionally, if a low-pass filter with a predetermined frequency is provided to prevent this hunting, attitude control will be performed according to the frequency of the low-pass filter, which may result in poor responsiveness during turning, braking, or acceleration. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide an electronically controlled suspension device that improves the responsiveness of attitude control.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration as a means for solving the problems. That is, as shown in FIG. 1, it has a displaceable suspension M2 provided corresponding to the wheel M1 of the vehicle, and a displacement detecting means M3 for detecting displacement.
The attitude control means M5 changes the suspension M2 to a target attitude based on the output signal of the mode conversion means M4 which calculates at least one of the roll displacement amount and the pitch displacement amount representing the vehicle attitude from the displacement of each wheel M1 detected by the An electronically controlled suspension system that performs feedback control to control the attitude of the vehicle includes a driving state detecting means M6 that detects the driving state of the vehicle, and an output signal from the mode converting means M4 at a predetermined frequency to determine the attitude. When the driving state detected by the driving state detecting means M6 and outputted to the control means M5 is a state in which acceleration is predicted to occur in the vehicle, an output from the mode converting means M4 corresponding to at least roll or pitch. This is a configuration of an electronically controlled suspension device characterized by comprising: a wave means M7 that filters one of the signals at a frequency higher than the predetermined frequency and outputs the filtered signal to the attitude control means M5.

[Function] In the electronically controlled suspension device having the above configuration, the mode conversion means M4 calculates at least one of the roll displacement amount and the pitch displacement amount representing the vehicle attitude from the displacement of each wheel M1 detected by the displacement detection means M3, The driving state detecting means M6 detects the driving state of the vehicle, and the Urahami means M7 filters the output signal from the mode converting means M4 at a predetermined frequency and outputs it to the attitude controlling means M5. When the detected driving state is a state in which acceleration is expected to occur in the vehicle, at least one of the output signals from the mode converting means M4 corresponding to roll or pitch is filtered at a frequency higher than the predetermined frequency. is output to the attitude control means M5, and the attitude control means M5
The suspension M2 is feedback-controlled based on the output signal from the filtering means M6. Therefore, the responsiveness of attitude control during roll and pitch is improved.

[Example] Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 2 is a schematic configuration diagram of an electronically controlled suspension device according to an embodiment of the present invention, and FIG. 3 is an air circuit diagram of the electronically controlled suspension device of this embodiment. This electronically controlled suspension device includes a suspension IFL on the left side of the front wheel, a suspension IFR on the right side of the front wheel, a suspension IRL on the left side of the rear wheel, and a suspension IRR on the right side of the rear wheel, which are each connected to an air circuit AC.
FL, IFR, IRL, and IRR each have a gas spring 2F.
L, 2PR, 2RL, 2RR and shock absorber 3F
L, 3FR, 3RL, and 3RR are provided.

These gas splashes 2PL, 2PR, 2R'L, and 2RR are each in the main gas chamber 4FL, as shown in FIG.

4FR, 4RL, 4RR and auxiliary gas chamber 5FL, 5FR, 5
Equipped with RL and 5RR, main gas chamber 4FL.

Some of 4PR, 4RL, and 4RR have diaphragm 6FL,
Since the main gas chambers 6FR, 6RL, and 6RR are formed, the vehicle height can be adjusted by supplying and discharging air to the main gas chambers 4FL, 4PR, 4RL, and 4RR. Also, gas springs 2FL and 2PR.

2RL and 2RR are spring constant switching actuators 7FL
, 7FR, 7RL, and 7RR, the main gas chambers 4PL, 4FR, 4RL, and 4RR and the auxiliary gas chamber 5FL,
By communicating/blocking 5FR, 5RL, and 5RR or switching the air flow rate, the spring constant can be changed to "low,""medium," and "high." In addition, the shock absorbers 3FL, 3FR, 3RL, and 3RR drive the damping force switching actuators 8FL, 8FR, 8RL, and 8RR to change the flow rate of oil passing through the orifice in the piston to set the ffl1 damping force to "low". It can be changed to "medium" and "high" levels.

On the other hand, each gas spring 2FL is provided in the air circuit AC.

A compressor 10 driven by a motor 9 is provided as a source of compressed air to be supplied to 2PR, 2RL, and 2RR, and the discharge side of this compressor 10 is connected to an air dryer 14 and exhaust air through a check valve 12 that prevents backflow. Each is connected to a switching valve 16. The air dryer 14 is filled with silica gel and removes moisture from the compressed air. This air dryer 14 is connected to a supply switching valve 22 and a connection switching valve 24, which can communicate and shut off, via a check valve 20 that prevents a fixed flow and backflow. The other side of the supply switching valve 22 is connected to a relief valve 25 set at a predetermined pressure, and is also connected to a high-pressure reserve tank 28 on the front wheel side via a high-pressure reserve switching valve 26 that can communicate and shut off. It is connected to a high-pressure reserve tank 32 on the rear wheel side via a high-pressure reserve switching valve 30 that can also be communicated and shut off. These high pressure reserve tanks 28.32
includes pressure sensors 34, 36 that detect the air pressure within the high-pressure reserve tank 28, 32, and a relief valve 38, 36 that is set to a predetermined pressure. 40 are arranged respectively.

Furthermore, the other of the supply switching valves 22 is connected to the main gas chamber AFL via a leveling valve 42 that can be communicated with and shut off.
It is connected to the main gas chamber 4FR via the leveling valve 44, to the main gas chamber 4RL via the leveling valve 46, and to the main gas chamber 4RR via the leveling valve 48, respectively. Each main gas chamber 4PL, 4FR, 4RL, 4R
R is a pressure sensor 50 for detecting air pressure. 52.
54° and 56 are connected to each other.

In addition, the main gas chamber 4FL on the left side of the front wheel is connected to a low pressure reserve tank 62 on the front wheel side through a discharge valve 5 which can be connected and shut off, and the main gas chamber 4FR on the right side of the front wheel is connected to a low pressure reserve tank 62 on the front wheel side through a similar discharge valve 60. It is connected. Furthermore, the main gas chamber 4RL on the left side of the rear wheel is connected to the low pressure reserve tank 6 on the rear wheel side through a discharge valve 64 that can be communicated with and shut off, and the main gas chamber 4RR on the right side of the rear wheel is connected to the low pressure reserve tank 6 on the rear wheel side through a similar discharge valve 66. Each day is connected. On the other hand, the low pressure reserve tank 62 on the front wheel side and the low pressure reserve tank 68 on the rear wheel side are connected so as to be able to communicate at all times. These low pressure reserve tanks 62, 68 are equipped with pressure sensors 70. 72 are connected to each other, and a relief valve 74 set at a predetermined pressure is connected to the low pressure reserve tank 62 on the front wheel side.

Both of these low pressure reserve tanks 62 and 68 are connected to the other of the connection switching valves 24, and are connected to the compressor 10 via a suction switching valve 76 that can be communicated and shut off.
connected to the suction side of the

Further, a check valve 7 is connected to the suction side of the compressor 10 so that atmospheric air can be sucked in.

Without installing this check valve 7 days, air circuit A
It is also possible to configure C as a completely closed circuit and to introduce air or other gas, such as nitrogen gas, into the air circuit AC.

The exhaust switching valve 16, the supply switching valve 22, the connection switching valve 24, and the high pressure reserve switching valve 26.
30. Leveling valve 42. 44°46. 4B,
Discharge valve 5B, 60°64, 66,
In this embodiment, the suction switching valve 76 uses a normally closed type.

In this air circuit AC, a high pressure reserve tank 28.32 and a low pressure reserve tank 62.6 are provided on the front wheel side and the rear wheel side, respectively.
Although 8 is provided, one high pressure reserve tank and - number of low pressure reserve tanks may be provided in common on the front wheel side and the rear wheel side.

Furthermore, as shown in Figure 2, the distance between the left front wheel and the vehicle body,
That is, a vehicle height sensor 80 detects the left front vehicle height, a vehicle height sensor 82 similarly detects the right front vehicle height, a vehicle height sensor 84 that detects the left rear vehicle height, and a vehicle height sensor 84 that detects the right rear vehicle height. A vehicle height sensor 86 is provided respectively. Each of the vehicle height sensors 80°82, 84, 86 outputs a signal corresponding to a positive vehicle height difference when the vehicle height is higher than a predetermined reference vehicle height, and a negative signal when the vehicle height is lower than that. Outputs a signal according to the height difference. On the other hand, a brake switch 87 detects that the brake pedal is depressed, a throttle valve opening sensor 88 detects the opening of a throttle valve that regulates the intake air amount of an internal combustion engine (not shown), and a steering wheel 8.
9, a well-known acceleration sensor 92 that detects the lateral and longitudinal acceleration of the vehicle body, and a vehicle speed sensor that detects the vehicle speed from the rotational speed of the output shaft of a transmission (not shown). 93, a door switch 94 provided for each door of the vehicle to detect the closed state of the door, and a neutral switch 95 to detect that the shift state of the transmission is neutral. In addition, the vehicle height switch 9 allows you to specify the vehicle height by manual operation.
7 and a vehicle height low switch 9.

Next, the electrical system of this embodiment will be explained using the block diagram shown in FIG. Each suspension IFL, IFR
, IRL, and IRR are driven and controlled by the electronic control circuit 100 to control the attitude of the vehicle. As shown in FIG. 4, this electronic control circuit 100 includes a well-known CPU 102. R
OM 104° RAM 106 is configured as the center of the logic operation circuit, and input/output circuits perform external and human output, in this case, an actuator drive circuit 108, a valve drive circuit 110,
A sensor input circuit 112, a level input circuit 114, etc. are connected to each other via a common bus 116.

The CPU 102 uses the pressure sensor 34. 36. 50°52, 54. 56. 70. 72, vehicle height sensor 8
0°82, 84. 86, signals from the throttle valve opening sensor 88, steering angle sensor 90, acceleration sensor 92, and vehicle speed sensor 93 are sent to the brake switch 87, door switch 94, neutral switch 95, and vehicle height high switch via the sensor input circuit 112. 97 and the signals from the vehicle height low switch 9 are input manually via the level input circuit 114. On the other hand, these signals, ROM104, R
Based on the data in the AM 106, the CPU 102 controls the compressor motor 9, spring constant switching actuators 7FL, 7FR,
7RL, 7RR and damping force switching actuator 8FL
, 8FR, 8RL, and 8RR, and outputs a drive signal to drive the exhaust switching valves 16., 8FR, 8RL, and 8RR via the valve drive circuit 110.
Supply switching valve 22, connection switching valve 24, high pressure reserve switching valve 26.30, leveling valve 42.4
4. 46°48, discharge valve 5B, 60
．． 64° 66, outputs a drive signal to the intake switching valve 76, and each suspension IFL, IFR, IRL, IRR
is under control.

The ROM 104 stores maps shown in FIGS. 10 to 21 and 23 to 28, which will be described later.

Next, the processing performed in the above-mentioned electronic control circuit 100 will be explained with reference to flowcharts shown in FIGS. 5 to 9.

FIG. 5 is a general flowchart showing an example of air suspension control according to the present invention, and FIGS. 6 to 9 are flowcharts showing detailed processing thereof.

The process shown in FIG. 5 is repeatedly executed in predetermined cycles.

First, when the process is started, it is determined in step 103 whether or not it is the first process after the power is turned on. If it is the first process, in step 105 the amount of paddy of various flags φ variables is set. Next, the output signals of the various sensors described above are read by the stepper 110.

Next, in step 200, gas splashes 2FL, 2 of the suspension IFL, IFR, IRL, and IRR when the vehicle rolls.
Among the air supply and discharge controls for FR, 2RL, and 2RR, feedforward control is executed. This feedforward control calculates a predicted acceleration GRLM which is an acceleration in a direction perpendicular to the vehicle traveling direction, that is, a lateral acceleration, which will be applied to the vehicle later due to steering, and according to the predicted acceleration GRL, Gas splash 2FL, 2FR, 2RL.

This is a control that attempts to prevent rolls or adjust to a predetermined inclination by adjusting the air pressure of the 2RR.

Next, in step 400, feedback control is executed among similar supply/discharge controls. This feedback control is used to stabilize the vehicle's attitude when the acceleration of the vehicle is relatively stable.
This control attempts to adjust the air pressure of RL and 2RR.

Next, in step 700, a corrected total pressure calculation for each wheel is executed, and the sum of the pressure correction amounts obtained by the feedforward control and feed pump control is determined as the corrected total pressure.

Next, in step 800, high pressure reserve switching valves 26, 30, leveling valves 42, . 44. 46°48, and discharge valve 5B, 60. Valve control is performed to open and close necessary valves among 64 and 66.

Details of the feedforward control, feedback control, corrected total pressure calculation for each wheel, and valve control will be explained.

FIG. 6 represents a flowchart of feedforward control. First, in step 210, filtering processing is performed on each signal. In other words, the data read this time is
(n), the value after the previous filtering is Y (n-1
), and the filtering constant is If (=1 to 256), the output Y (n) due to filtering is expressed by the following equation.

This process is a process for canceling out noise in detected data and averaging the leveling of data of frequencies higher than a predetermined value.

Next, a series of determination processes are performed to detect the state of the vehicle attitude change factor. That is, in step 220, the door switch 94 of the vehicle determines whether all the doors are closed, and in step 230, the neutral switch 95 determines whether the transmission is in the neutral state. At 240, it is determined by the throttle valve opening sensor 88 whether the throttle valve is fully open, and at step 250, among the suspension control valves, especially the high pressure reserve switching valves 26 and 3
0, leveling valve 42. 44. 46°48, discharge valve 58. 60. At steps 64 and 66, it is determined whether the vehicle height control of the suspension is being executed, and at step 260, the vehicle speed sensor 93 determines whether the vehicle speed is lower than a predetermined vehicle speed vO. Among these steps, Step 220, 230, 240, 26
0 is a factor that changes the attitude of the vehicle (opening/closing of a door to indicate when a passenger gets in or out of the vehicle, and shifting of the transmission to indicate the state of transmission of driving force to the tires).

This is a step of detecting the state of the amount of intake air to the internal combustion engine, which indicates the driving force itself, and the vehicle speed, which does not indicate the running state, and step 250 detects the state of the gas springs 2FL and 2PR.

This is a step of detecting that gas is not being supplied or discharged to adjust the air pressure of 2RL and 2RR.

If all of these conditions are affirmatively determined, the attitude of the vehicle is in a stable state and the gas spring 2PL is applied.

Since no large pressure fluctuations have occurred in 2FR, 2RL, and 2RR, and it can be predicted that the atmospheric pressure is stable, in step 270, each pressure sensor 50, 2RR at that time is
52, 54.56 as each reference pressure P FLA, P
RAM1 as FRA, P RLA, P RRA
Stored in 06. The filtering constant If used in step 210 is set such that this pressure value is a value filtered with a low-pass filter of a lower frequency than the filtering in step 210, for example, 5 Hz.
is set.

If a negative determination is made in any of steps 220 to 260, step 270 is not executed, and the reference pressures PFLA, PFRA, PRLA, and PRRA are not newly set. That is, as long as the conditions are met,
Constantly each reference pressure P FLA, P FRA, PRLA.

P RRA is updated.

Then after processing step 270 or step 220
~ If even one of the steps is negative in step 260, the estimated lateral acceleration 6RL of the vehicle is determined in step 280.
It is determined from the vehicle speed V and the steering angle θ based on the map shown in FIG. The graph corresponding to the map in FIG. 10 shows only the cases of two different predetermined accelerations with two broken lines, and since the other relationships are the same, their description is omitted.

Of course, other acceleration values may be obtained by interpolation calculation.

Next, in step 290, the estimated lateral jerk 6RL of the vehicle is determined from the vehicle speed V and the steering angular velocity 0, which is the differential value of the steering angle θ, based on the map shown in FIG. Note that the steering angular velocity O is the steering angle θ within a predetermined period.
It is also possible to use the difference value. The graph corresponding to the map in FIG. 11 shows only the cases of eight different steering angular velocities θ with eight broken lines, and the values between them are determined by interpolation calculation.

Next, in step 300, predicted acceleration GRLM is calculated by linear combination of the following formula.

GRLM = m-6RL+ h-ilZRL where, m
and h represent a constant, and have a value appropriately determined through experiments or the like in order to predict the roll.

Next, in step 310, each suspension IFL,
IFR, IRL, IRR gas springs 2PL, 2FR, 2
Each target pressure difference ΔPFLM, ΔPFRM of RL and 2RR,
ΔPRLM and ΔP RRM are calculated. That is, if the horizontal axis is the predicted acceleration GRLM [G] and the vertical axis is the target pressure difference [kgf/cm2], then each target pressure difference ΔPFL
M, ΔPFRM, ΔP RLM, and ΔPRRM have a relationship as shown in the figure, and are expressed as in the following formula.

ΔPFLM= a φGRLM ΔPFRM = −a φGRLM ΔPRLM= b Conflict GRLMΔP RRM=
-bφGRLM Here, a and b are coefficients for correcting variations in the suspension characteristics, and are expressed as in the following equation.

Here, W is the amount of sprung mass, h is the height of the center of gravity, tf is the front tread, tr is the rear tread, rf is the front arm ratio, rr is the rear arm ratio, Af is the front pressure receiving area, and A
r is the rear pressure receiving area, L is the wheel base, and Lr is the distance between the rear wheel and the center of gravity. Also, Kf is (L/Lr)>Kf≧
An arbitrary value set within the range of i and o represents the front shared load increment, and when Kf=1.0, the front shared load is 50%. By arbitrarily setting this Kf, the steering characteristics of the vehicle can be arbitrarily set.

However, in order to prevent repeating minute adjustments due to fluctuations in calculated values, detection errors, noise, etc., -1≦G R
If LM≦i, ΔPFLM=ΔP FRM=ΔPR
LM=ΔPRRM=0 is set, and a fuwazai zone is provided.

Next, in step 320, each target pressure PFLM.

P FRM, P RLM, and P RRM are calculated as shown below.

PFLM=ΔPFLM+PFLA PFRM=ΔP FRM+P FRAPRLM=Δ
PRLM + PRLA PRRM=ΔPRRM + PRRA This determines each pressure to be controlled.

Next, in step 330, each pressure deviation eFL, eF
R, e RL, and e RR are calculated as shown below.

eFL= PFLM -PFL eFR= PFRM -PFR eRL= PRLM -PRL eRR= PRRM -PRR Here, PFL, PFR, PRL, PRR are:
These are values obtained by filtering the outputs of pressure sensors 50, 52, 54, and 56 provided in the main gas chambers 4FL, 4FR, 4RL, and 4RR of each suspension IFL, IFR, IRL, and IRR.

Next, in step 340, in order to convert each pressure deviation into a control manipulated variable, each feedforward gain kl is
Based on the map shown by the dotted line in Fig. 13, the predicted acceleration G
It is determined according to the difference between RLM and actual lateral acceleration GRL. When I GRLM-GRLI is below q, 1=0, when above Q, kl = T, and between that, I GRLM
-GRL The relationship is such that it increases in accordance with an increase in l. However, k2°k3 compensates for the gain of feedback control, which will be described later. That is, the predicted lateral acceleration G
This indicates that the greater the difference between RLM and the current lateral acceleration GRL, the greater the contribution rate of feedforward control to the actual control amount.

Next, in step 350, using 1 as the gain and each pressure deviation e FL, e FR, e RL, e RR, each suspension IFL, IF
R.

Feedforward pressure amount CIFL to IRL and IRR
, c IFR, c IRL, and c IRR are calculated.

clFL = ki eFL clFR = kl◆eFR clRL = ki eRL clRR = klφeRR In this way, feedforward calculation processing is performed, and feedforward pressure amounts c IFL, c IFR
, c IRL, and c IRR are calculated.

Step 280.2 of the above feedforward calculation process
At 90, the estimated lateral acceleration dRL of the vehicle is the 10th
The estimated jerk 6RL in the lateral direction of the vehicle is calculated from the vehicle speed ■ and the steering angle θ based on the vehicle speed shown in the figure.
Based on the map shown in Figure 1, it is determined from the vehicle speed ■ and the steering angular velocity θ, but if longitudinal acceleration is captured instead of lateral acceleration, pitch can be countermeasured. That is,
As shown in FIG. 23, the estimated acceleration δFR in the longitudinal direction of the vehicle is calculated from the vehicle speed V and the throttle opening θT)l determined by the throttle valve opening sensor 88, and as shown in FIG. The estimated jerk ratio FR in the longitudinal direction of the vehicle may be determined from the above, and the predicted longitudinal acceleration GFRM may be calculated from both in the same manner. In this way, it will be a countermeasure against sfuoto in the pitch.

In addition, as another countermeasure for SFO, the rotational speed N of the internal combustion engine is used instead of the vehicle speed V, and the estimated acceleration 6FR in the longitudinal direction of the vehicle is calculated from the rotational speed N and the throttle opening θTH, as shown in FIG. , as shown in FIG. 26, the estimated longitudinal jerk FR of the vehicle is determined from the rotational speed N and the throttle opening speed θT), and the predicted longitudinal acceleration G FRM is similarly calculated from both. Good too.

The rotational speed is linked to the crankshaft of the internal combustion engine (not shown), and a signal corresponding to the rotational speed is sent to the electronic control circuit 10.
It is detected by the rotation speed sensor which outputs 0.

Furthermore, as a countermeasure against diamond in the bottle opening, instead of the throttle valve opening θTH and opening speed 6TH,
Using the brake pedal depression amount θBR and its depression speed OBR, the estimated acceleration in the longitudinal direction of the vehicle 6FR is calculated from the vehicle speed ■ and the brake depression amount θSR, as shown in FIG.
As shown in FIG. 28, the estimated jerk 15FR in the longitudinal direction of the vehicle may be obtained from the vehicle speed V and the brake depression speed θBR, and the predicted longitudinal acceleration GFRM may be calculated from both in the same manner. . The brake depression amount θBR and its depression speed 19BR are detected by a brake depression amount detection sensor that outputs a signal corresponding to the depression amount to the electronic control circuit 100 in conjunction with a brake pedal (not shown). In this way, in this embodiment, by a routine not shown, not only rolls but also dives,
The suspension is also controlled during auto mode.

Next, the feedback calculation process shown in FIG. 7 is performed. First, in step 410, each suspension IFL
, the output values XFL, XFR, of the vehicle height sensors 80.82, 84.86 installed in IFR, IRL, and IRR,
XRL, XRR response UT, and the lower equations calculate the respective displacements, that is, the vertical displacement amount XH, pitch displacement amount XP, roll displacement amount XR5, and torsional displacement amount XW representing the vehicle posture.

XI = (XFR+XFL) + (XRR+XRL
)XP = (XFR+XFL) -(XRR+XRL
)XR= (XFR-XFL) + (XRR-XRL
)X= (XFR-XFL) -(XRR-XRL)
Here, XFR represents the vehicle height of the right front wheel, XFL represents the vehicle height of the left front wheel, XRR represents the vehicle height of the right rear wheel, and XRL represents the vehicle height of the left rear wheel.

Next, at step 420, the roll displacement amount XR, which will be described later, is
The filtering constant in the filtering process is K
It is determined whether or not it is IO. If a negative determination is made, a series of determination processes are performed in order to detect a state in which lateral acceleration is expected to occur in the vehicle.6 In other words, in step 430, the vehicle speed sensor 93 detects that the vehicle speed is equal to or higher than a predetermined speed Va. For example, it is determined whether or not the speed is greater than or equal to 20 m/h,
In step 440, the steering angle sensor 90 determines whether the steering angle α is greater than or equal to a predetermined steering angle 08, for example, greater than or equal to 30 degrees. If an affirmative determination is made in both stems, it is determined that the vehicle is in a state in which lateral acceleration is expected to occur, that is, a roll is expected to occur, and in step 450, the filtering constant KFR of the roll displacement amount XR is determined. KIOl
For example, filter with a lOH2 low-pass filter (set directly).

Also, by repeatedly executing this routine, step 420
If an affirmative determination is made in step 460, the steering angle sensor 90 detects that the steering angle α is equal to or less than a predetermined steering angle αb, for example, 1
It is determined whether the temperature is 0 degrees or less. That is, the steering wheel 89
If the steering wheels 89 have not been returned, this routine is repeated, and if the steered wheels 89 are not returned to a state where roll occurs, such as in a straight running state under a predetermined steering angle abu, then in step 470, the process of the steps described later is performed. It is determined whether the set T1 time has elapsed.

Next, in step 480, it is determined whether or not a timer has been set by processing in steps to be described later. If a negative determination is made in step 480, a timer for time T1, for example 0.5 seconds, is set in step 490. When the timer is set and it is determined in step 470 that the time T1 has elapsed, the filtering constant KFR of the roll displacement amount XR is set to 1 in step 500.
For example, set the value to be filtered by an IH2 low-pass filter. Here, the relationship between Kl and KIO is Kl
When filtering processing, which will be described later, is performed at O, the filtering processing is performed at a higher frequency than when filtering processing is performed at K1.

Subsequently, in step 510, the timer of time T1 set in the process of step 490 is reset.

That is, when the vehicle speed V is a predetermined speed Va or more and the steering angle α is a predetermined angle 08 or more, it is determined that roll is occurring, and the filtering constant KFR is used when filtering the signal of the roll displacement amount XR. 'j;tK10
shall be. Further, when the steering angle α remains below the predetermined angle αb for more than T1 time, it is determined that roll is not occurring, and the filtering constant K FRlitK 1 is used when filtering the signal of the roll displacement amount XR.

On the other hand, if a negative determination is made in steps 430, 440, and 460, or if steps 450, 490, and 510 are executed, filtering in the pitch displacement amount xP filtering process described later is performed in step 520. It is determined whether the constant is KIO. If a negative determination is made, determination processing is performed to detect a state in which longitudinal acceleration is expected to occur in the vehicle. That is, in the stem 530, it is determined by the brake switch 87 whether or not the brake pedal is being depressed. Also,
In step 540, the throttle valve opening degree sensor 88 detects whether or not the time it takes for the throttle valve opening degree θTH to pass through three sections out of the six predetermined sections is within a predetermined time of 12, for example, within 0.15 seconds. Determine whether If an affirmative determination is made in any step, it is determined that the vehicle is in a state in which acceleration in the longitudinal direction is expected to occur, that is, a state in which pitch occurs, and in step 550, the pitch displacement f is determined.
Set the filtering constant KFP of tXP to KIOl, for example 1
0) (Set to a value to be filtered by the Z low-pass filter. Next, in step 560, a 13-hour timer is set.

On the other hand, if an affirmative determination is made in step 520, it is determined in step 570 whether or not the 13 hours of the timer set in step 560 have elapsed. After 13 hours of repeatedly executing this routine, step 57
If an affirmative determination is made in step 580, the filtering constant RFP of the pitch displacement amount xP is set to 1, for example, I
Set the value to be filtered by the M2 low-pass filter. Next, in step 590, the timer set by executing the process in step 560 is reset. That is,
When the brake pedal is depressed to decelerate or the throttle valve is opened to accelerate, the pitch displacement amount
The filtering constant K FPttK when filtering the signal of P is set to 10. In addition, when 13 hours have passed after setting to KIO, the filtering constant K when filtering the pitch displacement amount XP signal is
FPt2-K1.

Subsequently, in step 600, the vertical displacement ff1XH, the pitch displacement amount XP, the roll displacement amount XR5, and the torsional displacement amount X
1. Filtering processing for each signal of J is performed. ■
■Take the roll displacement amount XR as an example. If the data read this time is XR(n), the value after the previous filtering is XR(n-1), and the filtering constant is KFR, then the filtering output statement R( n) is expressed by the following formula.

XR(n)=KFR−XR(n)+(1−KFR)
Pitch displacement amount XP is also subjected to filtering processing in the same manner. That is, when the operating state is such that roll occurs, the roll displacement amount XR is filtered by a high-frequency low-pass filter using the filtering constant KIO, and when no roll occurs, the roll displacement amount XR is lower than the filtering constant Kl. Filtering is performed using a frequency low-pass filter. Furthermore, when the operating state is such that pitch occurs, the pitch displacement amount XP is filtered by a high-frequency low-pass filter using the fill multi-ring constant KIO, and when the pitch is not generated, the pitch displacement amount XP is filtered by the filtering constant Kl. Filtering is performed using a low-pass filter with a lower frequency. Further, in this embodiment, the vertical displacement amount XH1 and the torsional displacement amount XW are filtered using a constant filtering constant, for example, a filtering constant Kl using a low-frequency low-pass filter.

Next, in step 610, each mode deviation eH, eP, eR, eW is calculated as shown in the following formula based on the filtered XH, XP, XR, and Xυ. still,
XH, XP, XR, and X may be the difference values of XH, XP, XR, and X- over a predetermined period.

eH=Xt1M-X)I eP =XPM-XP eR=XRM-XR eW =XWM-XW Here, The mode selected with the high switch 97 or vehicle height low switch 98 (H-
AUTO or N-AUTO). XP
M is a target pitch displacement amount, which is determined from the actual acceleration GFR in the longitudinal direction of the vehicle detected by the acceleration sensor 92 based on the map shown in FIG. XRM is the target roll displacement amount, which is determined from the actual acceleration GRL in the vehicle lateral direction based on the map shown in FIG. iM is the target amount of torsional displacement and is normally zero.

Next, at step 620, each of the above displacements -mXH.

XP, XR, 1 (7) fii minute value minute value 9 sentences sentence 59 sentences R9
Based on the sentence -, each mode speed deviation white ■, as shown in the formula below.
^P and ^R9^- are calculated. Nao, text■.

Sentence R9 Sentence P1 Sentence R9 Sentence is Xl, XP, X
It may also be a difference value between R and XW for a predetermined period.

^H = Bundan) IM-Bun■ ^P = Bundan-BunP ^R = Bundan-BunR ^W: Bundan-BunW Here, Bundan) IM is the target vertical displacement speed, and usually It is zero. Sentence PM is the target pitch speed displacement amount, and the first
Based on the map shown in Figure 7, the jerk in the longitudinal direction of the vehicle is 6F.
It is determined from R. The sentence RM is the target roll displacement speed amount, which is determined from the vehicle lateral acceleration dRL based on the map shown in FIG. Text WM? This is the target torsional displacement velocity amount, which is normally zero.

Next, in step 630, 2H is applied to each feedback gain in order to convert each deviation into a control manipulated variable.

k2P, 2R, 2W (collectively referred to as k2), and 3H, k3P, k3R, k3W (collectively referred to as k3) are the predicted acceleration G based on the map shown by the solid line in FIG. It is determined according to the difference between RLM and actual lateral acceleration GRL. l GRLM - GRL When I is below q, 2, 3=T, and above Q, 2. 3=t
In between, the relationship is such that it decreases as lGRLM-GRLI increases. That is, the smaller the difference between the predicted acceleration GRLM and the current lateral acceleration GRL, the larger the contribution rate of the feedback control to the actual control amount.

Next, in step 640, each mode 1 shoulder difference el-1°eP, eR, eW and each mode speed deviation ^H', eP are determined.

From eR and eW, each feedback amount D is calculated as shown in the formula below.
H, DP, DR, and DW are calculated.

DI = 2H◆ etl + k3 ■Conflict eH
+ to 4HDP = to 2P+ eP + to 3P◆eP
+ to 4PDR= to 2R◆eR+ to 3RφeR+ to 4
RDW=2W◆eW+3w◆eW+4W However, k4H, k4P, k4R, k4- are predetermined constants.

Next, in step 650, each of the above feedback amounts DI
(Based on DP, DR, and DW, each suspension IFL, IFR, and IRL is determined by the following formula.

IRR feedback amount DEL, DFR, DRL
, DRR is calculated.

DFL = 1/4 (ko old D ll + 2 k OP◆LfφDP-
k 0R-D R-k OW-D W)DFR= 1/410H-D)! +2kOP-Lf-DP10kOR
-DR+k 0W-DW) DRL=1/4(k 0H-D H-2k OP・(1-Lf)
・DP-kORφD R+ k OW◆DW)DRR= 1/4(kOH-D 1l-2kQP・(1-Lf)・
DP+k OR-D R-k OW◆DW) Kokote, k
OH, kOP, kOR, and kOW use predetermined coefficients, and Lf uses a distribution coefficient between the front and rear wheels that takes into account the position of the vehicle center of gravity within the wheel base.

Next, in step 660, the feedback amount D
Based on FL, DFR, DRL, and DRR, each feedback pressure jt c 2FL, c is calculated using the following formula.
2FR, c2RL, and c2RR are calculated.

c 2FL= P FL building a2FL ◆D FLc
2FR= P FR◆a2FR◆D FRc2RL=
PRL◆a2RL◆DRL c2RR=PRR◆a2RR◆DRR Here, PFL, PFR, PRL, PRR are
The outputs of the pressure sensors 50, 52, 54, and 56 provided in the main gas chambers 4FL, 4FR, 4RL, and 4RR of each suspension IFL, IFR, IRL, and IRR are filtered (directly.a 2FL, a 2FR, a
2RL and a2RR are predetermined coefficients.

In this way, the feedback calculation process is performed, and the feed pump pressure amounts c 2FL, c 2PR, c
2RL.

c 2RR is calculated.

Next, in step 710 shown in FIG. 8, a corrected total pressure calculation process is performed. That is, as shown in the formula below, the feedforward pressure amounts c IFL, c IFR, c IRL, c IR calculated in the above feedforward calculation process are
R and the feed pump/punk pressure amount c 2FL, c 2FR, c 2RL calculated by the above feedback calculation process.
, c The total pressure amount c FL is corrected from the sum of 2RR,
c FR, c RL, and c RR are calculated.

c FL= c IFL+ c 2FLc FR= c
IFR+ c 2FRc RL-c IRL+ c
2RL c RR= c IRR+ c 2RRNext, in the valve control process shown in Fig. 9, each suspension IFL, IF
R, IRL, IRR main gas chamber 4PL, 4FR, 4RL
, 4RR is supplied and discharged.

That is, in step 810, in order to adjust the pressure of the main gas chambers 4PL, 4PR, 4RL, and 4RR based on the corrected total pressure amounts cFL, cFR, cRL, and cRR calculated above, high pressure is adjusted as shown in the following formula. Reserve switching valve 26. 30. Leveling valve 42. 44. 46
．． 48 or discharge valve 5B, 60°6
4.66 valve on times tFL, tFR, tR
L.

tRR is calculated.

When high pressure reserve switching valves 26, 30 and leveling valves 42, 44, 46, 48 are on, that is, pressure increases, tFL = (aF/φ) ◆ (cFL/PFH) tFR =
(aF/φ) φ(cFR/PFH)tRL= (aR
/φ) φ(c RL/P RH)tRR=(aR/
φ) φ(cRR/PRH) discharge valve 5B
, 60. 64. 66 on, that is, when the pressure decreases, tFL=(bF/φ) ・(cFL/PFL)tFR=
(bF/φ) ・(cFR/PFR)tRL=(bR/
φ) ・(cRL/PRL)tRR=(bR/φ) ・
(cRR/PRR) Here, aF/φ* aR/φ is the tank pressure P on the high pressure side based on the map shown in Figure 19.
Ratio Pi/P2 between I (=PFll or PRH) and the main gas chamber pressure P2 that receives gas from its high-pressure tank
required from. The tank on the high pressure side is the high pressure reserve tank 28.32 on the front wheel side or the rear wheel side, and is PFII
is the pressure of the high pressure reserve tank 2nd day on the front wheel side, PRII
is the pressure of the high pressure reserve tank 32 on the rear wheel side.

bF/φ and bR/φ are based on the map shown in Fig. 20,
It is determined from the ratio P2/P3 between the main gas chamber pressure P2 and the tank pressure P3 on the low pressure side from which gas is discharged from the main gas chamber. The tank on the low pressure side is the low pressure reserve tank 62, 68 on the front wheel side or the rear wheel side.

Next, in step 8200 on-time correction calculation processing, the valve on-times tFL, tFR, tRL, tRR are calculated.
Based on the following formula, the time during which the valve is actually driven (actual valve driving time) tFLU, tFRU
.

tRLU, tRRU(tFLD, tFRD, tR
LD, tRRD) are calculated.

When high pressure reserve switching valves 26, 30 and leveling valves 42, 44, 46, 48 are on, that is, pressure increases tFLU=αF4tFL+βFL t FRU=αF command tFR+βFR t RLLI=αR command tRL+βRLt RRU=α
R◆tRR+βRR discharge valve 58. 60. 64. 66 on, that is, in the case of pressure drop t FLD = γF command tFL + δFL t FRD = γFφtFR + δFR t RLD = γR◆tRL + δRL t RRD = rRΦtRR + δRR Here, αF, γF, αR9γR9βFL, βFR
, βRL.

βRR, δFL, δFR, δRL, and δRR have predetermined coefficients.

Next, in step 830, the actual valve driving time tFL
U, tFRU, tRLU, tRRU(tU
), tFLD, tFRD, tR
Guard processing of LD and tRRD (collectively referred to as tD) is performed. This prevents the switching times of the valve from on to off or off to on to be too short;
This is to protect the valve mechanism. That is, as shown in FIG. 21, if the actual valve driving times tU, tD with a duty of less than 30% are calculated, the actual valve driving times tu, to are set to zero, and the actual valve driving times tU, tD with a duty of less than 80% are calculated. When the driving times tu and to are calculated, the actual valve driving times tU and tD are fixed at a time corresponding to a duty of 80%.

Next, at step 840, at the actual valve drive times tu and to, the valve 26. 30°42, 44
．． 46. 48. 5B, 60. 64. 66
The opening time of the is controlled.

In this way, when the air suspension control process is once completed and the process is restarted after a predetermined control period, step 10
A negative determination is made in step 3, and the process proceeds from step 110. The same process is repeated thereafter. In this embodiment, the control period is 100 m5, and the valve 26. 30.
42.44. 46°48.5B and 60.64.66 are duty-controlled within this 100m5. In other words, 1
Valve 26. 30. 4
2, 44. 46. 48. 5B, 60. 6
4. 66 is 100m until the next drive signal is issued.
The duty is controlled for 5 hours.

As described above, in this embodiment, each target pressure P FLM, P FRM, P RLM, P is repeatedly set at predetermined time intervals.
RRM is calculated, and each suspension IFL, IFR, IRL, IRR is calculated at predetermined time intervals according to the target pressure value.
Since the pressures of the main gas chambers 4FL, 4PR, 4RL, and 4RR are adjusted, smooth pressure control corresponding to actual roll changes is possible. Therefore, the driver's discomfort is eliminated and high steering stability can be achieved.

That is, in the case of relatively slow steering as shown in FIG. 22(A), the predicted lateral acceleration GRLM (double-dashed line) and the actual acceleration GRL are actually different as shown in FIG. 22(B).
(solid line). In this embodiment, as shown in (C), the target pressure is calculated in a predetermined cycle (for example, 100 m5) and a valve drive signal is output. Therefore, (
Suspension IFL, IFR, IR as shown in D)
L, IRR gas chambers 4FL, 4FR, 4RL, 4RR
Since the pressure gradually increases in a stepwise manner according to the degree of increase in the predicted acceleration GRLM, the roll color can be suppressed to an extremely small level as shown in (E). In this way, the vehicle becomes more stable and the handling stability is improved.

On the other hand, when lateral acceleration is expected to occur and roll occurs, the roll displacement amount XR is filtered by a high-frequency low-pass filter using the filtering constant KIO, increasing the sensitivity of the roll displacement amount XR and controlling the posture. improves responsiveness. When there is no state where a roll will occur! j, the roll displacement amount XR is filtered by a low-frequency low-pass filter with a filtering constant of 1 to prevent the valve from causing operation hunting due to the influence of high-frequency vibrations such as when driving on a rough road. In addition, when acceleration in the longitudinal direction is expected to occur and pitch is generated, the pitch displacement xP is filtered by a high frequency low-pass filter using the filtering constant KIO, and the pitch displacement f4
The sensitivity of P is increased and the responsiveness of attitude control is improved. When no pitch occurs, the pitch displacement amount XP is filtered by a low-frequency low-pass filter using a filtering constant Kl to prevent the valve from operating hunting due to the influence of high-frequency vibrations such as when driving on a rough road.

In addition, in this embodiment, in addition to the estimated lateral acceleration 6RL of the vehicle, the predicted acceleration GRLM is calculated using the estimated lateral jerk dRL of the vehicle, so the attitude control is performed immediately before the attitude change of the vehicle. This enables more accurate feedforward control. Of course, using only the estimated acceleration 6RL or only the estimated jerk 16RL, the predicted acceleration G R
LM may also be calculated. In addition, the predicted acceleration G is calculated without using the estimated acceleration 6RL or the estimated jerk 11ZRL.
In calculating RLH, the direct actual acceleration GRL or the actual ship acceleration dRL, which is its differential value, may be used.

The predicted accelerations GRLM and GFRM obtained by taking measures against roll, suffoto, and dia are used alone in the suspension control described above and are useful for preventing each of roll, suffoto, and dia.In that case, switching the filtering constant is , and should be implemented according to the countermeasures. Furthermore, when these roll, square, and diamond countermeasures are taken into account, the filtering constant may be switched only for at least one of the roll and pitch countermeasures.

In addition, in the above embodiment, the vehicle height sensors 80, 82, 84
．． 86 corresponds to the displacement detection means M3, and the air circuit AC and steps 103 to 350. The processing from 610 to 840 corresponds to the processing of the attitude control means M5, and the processing of step 410 corresponds to the processing of the mode conversion means M4, and the processing of the brake switch 87, throttle valve opening sensor 88, steering angle sensor 90, and The vehicle speed sensor 93 corresponds to the driving state detection means M6, and steps 420 to 600
The processing corresponds to the processing of the filtering means M7.

Although the embodiments of the present invention have been described above, the present invention is not equally limited to these embodiments, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

As detailed above, according to the electronically controlled suspension system of the present invention, it is possible to prevent the equipment from hunting due to high-frequency vibrations caused by the influence of the road surface even when driving on a rough road, and also to prevent hunting during roll or pitch. , the sensitivity of the roll displacement amount and pitch displacement amount representing the vehicle attitude is increased, and the attitude side f
This has the effect of improving wholesaler responsiveness.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a schematic configuration diagram of an embodiment of an electronically controlled suspension device, Fig. 3 is an air circuit diagram of this embodiment, and Fig. 4 is an electrical circuit diagram of this embodiment. A block diagram showing the system configuration, FIG. 5 is a general flowchart of the control routine executed by the electronic control circuit of this embodiment,
Fig. 6 is a flowchart of the feedforward calculation process, Fig. 7 is a flowchart of the feedback calculation process, Fig. 8 is a flowchart of the corrected total pressure calculation process, and Fig. 9 is a flowchart of the valve control process. Flowchart, FIG. 10 is a graph representing a map for calculating estimated lateral acceleration aRL from steering angle θ and vehicle speed V, FIG. 11 is a graph representing a map for calculating estimated lateral jerk 6RL from steering angular velocity υ and vehicle speed V, and FIG. The figure shows predicted acceleration GRL
Target pressure difference ΔPFLM, ΔPFRM, ΔPRLM from M
, ΔP RRM, and FIG. 13 is a graph showing a map for calculating ΔP RRM. Based on the difference between the predicted acceleration GRLM and the actual lateral acceleration CRL, the feedforward gain is set to 1 and the feedback gain is set to 2. Graph representing the map for finding 3 in , No. 14
The figure is a graph corresponding to the map for calculating the target vehicle height based on the vehicle speed ■ and the mode, Figure 15 is the graph corresponding to the map for calculating the target pitch displacement XPM based on the actual longitudinal acceleration GFR, and Figure 16 is the graph for the actual lateral acceleration. The first graph corresponds to the map for determining the target roll displacement XRM based on GRL.
Figure 7 is a graph corresponding to a map for determining the target pitch displacement speed statement based on the actual longitudinal acceleration GFR, Figure 18 is a graph corresponding to a map for determining the target roll displacement velocity statement RM based on the actual lateral jerk dRL, and Figure 19 is a graph corresponding to the map for determining the target roll displacement velocity statement RM based on the actual lateral jerk dRL. The figure shows a coefficient aF based on the ratio Pi/P2 between the tank pressure P1 on the high pressure side and the main gas chamber pressure P2 that receives gas from the high pressure tank.
/φ. The graph corresponding to the map for calculating aR/φ, Figure 20, is the coefficient bF/φ based on the ratio P2/P3 of the main gas chamber pressure P2 and the low pressure side tank pressure P3 from which gas is discharged from the main gas chamber. , bR/φ, and FIG.
Figure 2 is a timing chart showing the effects of the embodiment, No. 23.
The figure is a graph showing a map for calculating the estimated longitudinal acceleration 6FR from the throttle opening θTll and the vehicle speed V, and Fig. 24 shows the estimated longitudinal jerk d from the throttle opening θTH and the vehicle speed V.
A graph showing a map for calculating FR, Fig. 25 is a graph showing a map for calculating estimated longitudinal acceleration 6FR from throttle opening θTel and internal combustion engine rotation speed N, and Fig. 26 shows a map for calculating front throttle opening υTH and internal combustion engine rotation speed. Graph representing a map for calculating estimated lateral jerk ratio FR from N, No. 27
The figure shows a map for calculating the estimated longitudinal acceleration dFR from the brake depression amount θBR and the vehicle speed V, and FIG. 28 shows the map for calculating the estimated longitudinal jerk 6FR from the brake depression rate d[lR and the vehicle speed V. . Ml...Wheel M2...Suspension M3...Displacement detection means M4...Mode conversion means M5...Attitude control means M6...Driving state detection means Ml...Filtering means IFL, IFR, IRL , IRR...Suspension 2PL, 2FR, 2RL, 2RR-... Gas spring 26.
30... High pressure reserve switching valve 34, 36.
50. 52. 54゜56.70.72...Pressure sensor 42.44.46.48...Belling valve 5B,
60, 64, 66...discharge valve 80.8
2,84.86...Vehicle height sensor 87...Brake switch 8th...Throttle valve opening sensor 90...Steering angle sensor 92...Acceleration sensor 93...Vehicle speed sensor 94... Door switch 95...neutral switch 100...electronic control circuit

Claims (1)

[Claims] The vehicle has a displaceable suspension provided corresponding to the wheels of the vehicle, and from the displacement of each wheel detected by a displacement detection means for detecting displacement, at least the amount of roll displacement or pitch representing the vehicle attitude is determined. In an electronically controlled suspension system that controls the attitude of the vehicle, the attitude control means feedback-controls the suspension to a target attitude based on the output signal of the mode conversion means that calculates one of the displacement amounts, and detects the driving state of the vehicle. An output signal from the driving state detecting means and the mode converting means is filtered at a predetermined frequency and outputted to the attitude controlling means, and the driving state detected by the driving state detecting means predicts that acceleration will occur in the vehicle. filtering means for filtering at least one of the output signals from the mode conversion means according to the roll or the pitch at a frequency higher than the predetermined frequency and outputting the filtered signal to the attitude control means; An electronically controlled suspension device characterized by: