JPH0744489Y2 - Electronically controlled suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an electronically controlled suspension device for preventing pitch or roll of a vehicle. In particular, the present invention relates to an electronically controlled suspension device that is highly responsive to changes in the vehicle state and that can perform smooth attitude control even during a transient acceleration of the vehicle.

[Prior Art] Conventionally, various devices for preventing a pitch and a roll of a vehicle have been proposed in order to improve riding comfort and steering stability. For example, a steady turn or a steep turn due to a slow steering is detected depending on whether or not the steering angular velocity is equal to or higher than a reference value. In the case of a steady turn, the flow rate of compressed air supplied to the gas spring is made small, and the steering angle-vehicle speed map Control time to obtain a relatively slow body attitude control, and in the case of a sharp turn, increase the flow rate of compressed air supplied to the gas spring and perform a quick vehicle attitude control using the steering angular velocity-vehicle speed map. A device has been proposed (Shokaisho 60-152510).

[Problems to be Solved by the Invention] However, in such a conventional electronically controlled suspension device, when a change in posture, that is, a roll is predicted from an estimated value of lateral acceleration and the roll portion is corrected by an air suspension, the correction is performed. The control speed is uniform, and the correction is performed at the same time.

Therefore, it is not possible to cope with a wide variety of acceleration changes due to subtle steering differences. That is,
When the control mechanism is designed to have a corrected control speed that emphasizes a sudden change in acceleration, the attitude control timing may be too early and the vehicle may cause a reverse roll when steering is relatively slow.

In such a case, an occupant may feel uncomfortable and is not preferable in terms of traveling stability.

The present application provides an electronically controlled suspension device that can respond to changes in acceleration applied to a vehicle with good responsiveness, suppress rolls and pitches, and realize extremely smooth attitude control.

Configuration and Effect of the Invention [Means for Solving the Problems] That is, the gist of the present invention is, as illustrated in the basic configuration diagram of FIG. 1, a vehicle traveling state detecting means for detecting a traveling state of a vehicle. Based on M3 and the running state of the vehicle detected by the vehicle running state detecting means M3, predict the acceleration of the vehicle that will arrive ahead of the control period of the fluid actuator M2 of the suspension provided on the wheel M1 of the vehicle In addition, based on this acceleration, the target correction pressure amount calculation means M4 for calculating the target correction pressure amount of the pressure in the fluid actuator M2 so as to suppress the change in the vehicle attitude caused by the acceleration, and the target correction pressure amount. In accordance with the target correction pressure amount calculated by the calculation means M4, the fluid supply / discharge control of the fluid in the fluid actuator M2 is performed at a cycle of the target correction pressure amount calculation cycle or more. An electronically controlled suspension device for adjusting the attitude of a vehicle, comprising: a supply / discharge control means M5 for controlling the attitude of the vehicle, wherein a compressive fluid is used as the fluid, and the supply / discharge control means M5 is configured to control the fluid actuator M2 and the compressible fluid. High-pressure reserve tank M6 and low-pressure reserve tank M7
The fluid supply / discharge control is performed by the duty control of an on / off control valve M8 disposed between the vehicle running state detection means M3 and the vehicle running state detection means M3. Detecting a parameter related to vehicle operation to be generated, the target correction pressure amount calculating means M4, based on the detected parameter, estimates the acceleration and jerk of the vehicle,
The electronically controlled suspension device is characterized in that the acceleration of the vehicle is predicted from the estimated acceleration and jerk.

[Operation and Effect] According to the electronically controlled suspension device of the present invention, the vehicle traveling state detection means M3 causes a parameter related to the vehicle speed of the vehicle (for example, the vehicle speed itself or the engine speed) and an acceleration change in the vehicle. A parameter related to vehicle operation (for example, steering, braking, acceleration itself, etc.) is detected. Then, based on this detection result, the target correction pressure amount calculation means M4 predicts the acceleration and acceleration (forward and backward and / or left and right) of the vehicle that will arrive ahead of the control period of the fluid actuator M2 or more. That is, if the control period of the fluid actuator M2 is, for example, 100 ms, the acceleration at which the vehicle is likely to be applied is predicted after that time or after a time longer than that time, and further, based on this predicted acceleration, the inside of the upstream fluid actuator M2 is predicted. The target correction pressure amount for correcting and changing the pressure is calculated. The supply / discharge control means M5, in accordance with this target correction pressure amount, at a cycle that is equal to or longer than the calculation cycle of the target correction pressure amount (for example, 100 ms as described above)
The supply / discharge control of the fluid in the fluid actuator M2 is executed.

More specifically, as parameters related to vehicle operation,
For example, if the steering angle is detected, the lateral acceleration can be estimated from the parameter relating to the vehicle speed and the steering angle, and the lateral jerk can be estimated from the parameter relating to the vehicle speed and the steering angular velocity. Then, from these lateral acceleration and lateral jerk, it is possible to predict the lateral acceleration of the vehicle that will arrive ahead of the control period or more. Since such lateral acceleration causes rolls in the vehicle, the target correction pressure amount is calculated in order to suppress such a posture change. Then, based on this target correction pressure amount, the duty control of the on / off control valve M8 is executed in a cycle equal to or longer than the calculation cycle of the target correction pressure amount.

In addition, as parameters related to vehicle operation, for example, if the throttle opening or the amount of brake depression is detected, the longitudinal acceleration and jerk can be estimated, and the target correction pressure amount is calculated as a countermeasure against squats and dives. The on / off control valve M8 can be duty-controlled.

In this way, the posture of the vehicle is smoothly controlled.

Further, in the present invention, since a compressive fluid (such as air) is used, a cushioning effect like an air spring is obtained, and riding comfort is good. Moreover, the entire system can be designed to have a low pressure as compared with the case of using hydraulic pressure, which is lightweight and inexpensive.

By the way, although a suspension system itself using a compressible fluid is conventionally known, in such a system, so-called one-shot control for setting the valve opening time of the on / off control valve according to the initial predicted acceleration is performed as feedforward control. Has been adopted. On the other hand, the present invention is completely new in that it uses feedforward control and duty control. By adopting this duty control, overshoot of control, which is a problem peculiar to a compressible fluid and which is caused by slow response, is eliminated, and stable control without hunting is made possible.

As described above, according to the present invention, no matter what pattern the acceleration increases or decreases, smooth feedforward processing can be performed according to the acceleration change, so that the driver does not feel uncomfortable and the vehicle is stabilized. Achieve high steering stability. In addition, it is possible to satisfy the comfort of riding, which is an effect peculiar to the compressible fluid, and to cover the slow response, which is its weak point, and to achieve stable posture control without hunting. Can be played.

Next, an embodiment of the present invention will be described. The present invention is not limited to these, and includes various embodiments without departing from the scope of the invention.

[Embodiment] FIG. 2 is a schematic configuration diagram of an electronically controlled suspension apparatus which is an embodiment of the present invention, and FIG. 3 is an air circuit diagram of the electronically controlled suspension apparatus of the present embodiment. This electronically controlled suspension system consists of a front wheel left suspension 1FL and a front wheel right suspension 1F which are connected to the air circuit AC.
R, suspension 1RL on the left side of the rear wheel, suspension 1RR on the right side of the rear wheel, this suspension 1FL, 1FR, 1RL, 1RR
Each is provided with a gas spring 2FL, 2FR, 2RL, 2RR and a shock absorber 3FL, 3FR, 3RL, 3RR.

The gas springs 2FL, 2FR, 2RL, 2RR are, as shown in FIG. 3, respectively the main gas chambers 4FL, 4FR, 4RL, 4RR and the sub gas chambers 5FL, 5FR, 5RR.
RL, 5RR and part of the main gas chambers 4FL, 4FR, 4RL, 4RR are formed by the diaphragms 6FL, 6FR, 6RL, 6RR, so air is supplied to the main gas chambers 4FL, 4FR, 4RL, 4RR. The vehicle height can be adjusted by removing it. Also, gas spring 2FL,
2FR, 2RL, 2RR are spring constant switching actuators 7FL, 7FR, 7
Main gas chamber 4FL, 4FR, 4RL, 4RR by driving RL, 7RR
And sub gas chambers 5FL, 5FR, 5RL, 5RR are connected or shut off or the air flow rate is switched to set the spring constant to "low", "medium",
You can change to each "high" stage. The shock absorbers 3FL, 3FR, 3RL, 3RR drive the damping force switching actuators 8FL, 8FR, 8RL, 8RR to change the flow rate of oil passing through the orifice in the piston to reduce the damping force to "low", " It can be changed to each level of "Medium" and "High".

On the other hand, the air circuit AC is provided with a compressor 10 driven by a motor 9 as a supply source of compressed air supplied to each of the gas springs 2FL, 2FR, 2RL, 2RR. It is connected to the air dryer 14 and the exhaust gas switching valve 16 via check valves 12 for preventing them. Silica gel is enclosed in the air dryer 14,
Remove water in compressed air. This air dryer 14 is a supply switching valve 22 and a connection switching valve that can be connected and disconnected through a fixed throttle 18 and a check valve 20 that prevents backflow.
24 connected to each. The other of the supply switching valve 22 is connected to a relief valve 25 set to a predetermined pressure, and a switching valve for high pressure reserve that can communicate and cut off.
It is connected to the high-pressure reserve tank 28 on the front wheel side via 26,
Similarly, a switching valve for high pressure reserve that can be connected and disconnected.
It is connected via 30 to a high-pressure reserve tank 32 on the rear wheel side. These high pressure reserve tanks 28, 32 have a pressure sensor 3 for detecting the air pressure in the high pressure reserve tanks 28, 32.
4, 36 and relief valves 38, 40 set to a predetermined pressure are provided respectively.

Further, the other of the supply switching valves 22 has a main gas chamber 4FL via a leveling valve 42 capable of communicating and blocking, a main gas chamber 4FR via a leveling valve 44, and a main gas chamber 4RL via a leveling valve 46. And the main gas chamber 4RR via the leveling valve 48, respectively. Each main gas chamber 4FL, 4FR, 4RL, 4RR has a pressure sensor 5 for detecting air pressure.
0, 52, 54 and 56 are respectively connected.

In addition, the main gas chamber 4FL on the left side of the front wheel is connected to the main gas chamber 4FR on the right side of the front wheel via a discharge valve 58 that can be connected and disconnected.
Are connected to the low-pressure reserve tanks 62 on the front wheels side via similar discharge valves 60. Furthermore,
The main gas chamber 4RL on the left side of the rear wheel is connected to the low-pressure reserve tank 68 on the rear wheel side via a discharge valve 64 that can communicate and shut off, and the main gas chamber 4RR on the right side of the rear wheel is connected via a similar discharge valve 66. It is connected. On the other hand, the front wheel low-pressure reserve tank 62 and the rear wheel low-pressure reserve tank
It is always connected to 68. Pressure sensors 70 and 72 for detecting the air pressure in the low-pressure reserve tanks 62 and 68 are connected to these low-pressure reserve tanks 62 and 68, respectively, and a relief valve 74 set to a predetermined pressure is provided in the low-pressure reserve tank 62 on the front wheel side. Are connected.

Both of the low pressure reserve tanks 62 and 68 are connected to the other of the connection switching valves 24, and are also connected to the suction side of the compressor 10 via a suction / switch valve 76 capable of communicating / cutting off. Also, on the suction side of the compressor 10,
A check valve 78 is connected so that the atmosphere can be inhaled.
It is also possible to configure the air circuit AC as a completely closed circuit without providing the check valve 78 and to put air or another gas, for example, nitrogen gas in the air circuit AC.

The exhaust switching valve 16, the supply switching valve 22, the connection switching valve 24, the high pressure reserve switching valves 26, 30, the leveling valves 42, 44, 46, 48, the discharge valves 58, 60, 6
In this embodiment, 4, 66 and the suction switching valve 76 are normally closed type.

In this air circuit AC, high pressure reserve tanks 28 and 32 and low pressure reserve tanks 62 and 68 are provided on the front wheel side and the rear wheel side, respectively, but one high pressure reserve tank and one common one for the front wheel side and the rear wheel side are provided. The low-pressure reserve tank may be provided.

Furthermore, as shown in FIG. 2, the distance between the front left wheel and the vehicle body,
That is, a vehicle height sensor 80 that detects the left front vehicle height, a vehicle height sensor 82 that also detects the right front vehicle height, a vehicle height sensor 84 that detects the left rear vehicle height, and a right rear vehicle height. Each vehicle height sensor 86 is provided. This vehicle height sensor
80,82,84,86 responds to a signal that corresponds to a positive vehicle height difference when the vehicle height is higher than a predetermined reference vehicle height, and responds to a negative vehicle height difference when the vehicle height is lower than that. Output a signal.
On the other hand, a well-known steering angle sensor that detects the steering angle of the steered wheels 88.
90, a well-known acceleration sensor 92 that detects lateral and longitudinal accelerations of the vehicle body, a vehicle speed sensor 93 that detects a vehicle speed from the rotation speed of an output shaft of a transmission (not shown), and a door provided for each door of the vehicle. A door switch 94 for detecting the closed state,
The transmission is provided with a neutral switch 95 for detecting that the shift state of the transmission is neutral, and a throttle opening sensor 96 for detecting the opening of a throttle valve that regulates the intake air amount of an internal combustion engine (not shown). Further, a vehicle height high switch 97 and a vehicle height low switch 98 for instructing the vehicle height by manual operation are provided.

Next, the electric system of this embodiment will be described with reference to the block diagram shown in FIG. Each suspension 1FL, 1FR, 1RL, 1R
The R is 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 is configured with a well-known CPU 102, ROM 104, RAM 106 as the center of a logical operation circuit, and an input / output circuit for performing input / output with the outside,
Here, actuator drive circuit 108, valve drive circuit 1
10, a sensor input circuit 112, a level input circuit 114, etc. are connected to each other via a common bus 116.

CPU 102 is a pressure sensor 34, 36, 50, 52, 54, 56, 70, 72, a vehicle height sensor 80, 82, 84, 86, a steering angle sensor 90, an acceleration sensor 9
2, the signal from the vehicle speed sensor 93, the throttle opening sensor 96 through the sensor input circuit 112, the signal from the door switch 94, the neutral switch 95, the vehicle height high switch 97 and the vehicle height low switch 98, the level input circuit Enter via 114. On the other hand, based on these signals and the data in the ROM 104 and RAM 106, the CPU 102 causes the actuator drive circuit 108
A drive signal for driving the compressor motor 9, the spring constant switching actuators 7FL, 7FR, 7RL, 7RR and the damping force switching actuators 8FL, 8FR, 8RL, 8RR is output via
Exhaust gas switching valve 16, supply switching valve 22, connection switching valve 24, high pressure reserve switching valve 26, 30, leveling valve 42, 44, 46, 48, discharge valve 58, 60, 64, 66 via valve drive circuit 110. A drive signal is output to the intake switching valve 76 to control each suspension 1FL, 1FR, 1RL, 1RR.

The ROM 104 includes the later-described FIGS. 10 to 21 and 23 to 28.
The map shown in the figure is stored.

Next, the processing performed in the electronic control circuit 100 described above will be described with reference to the flowcharts of FIGS.

FIG. 5 is a general flow chart showing an example of the air suspension control in the present invention, and FIGS. 6 to 9 are flow charts showing the detailed processing thereof.

The process of FIG. 5 is repeated and executed at a predetermined cycle.

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, various flags and variables are initialized in step 105.
Next, in step 110, the output signals of the various sensors described above are read.

Next, in step 200, the suspension 1F when the vehicle rolls
The feedforward control is executed in the air supply / discharge control for the gas springs 2FL, 2FR, 2RL, 2RR of L, 1FR, 1RL, 1RR. This feed-forward control is an acceleration applied to the vehicle thereafter by steering, in a direction perpendicular to the vehicle traveling direction,
That is, the predicted acceleration GRLM that is the lateral acceleration is calculated, and the gas springs 2FL, 2FR, 2 are calculated according to the predicted acceleration GRLM.
This is a control for adjusting the atmospheric pressure of RL, 2RR to prevent the roll from occurring or to adjust it to a predetermined inclination.

Next, in step 400, feedback control is executed among the similar supply / discharge control. This feedback control is a control for adjusting the atmospheric pressure of the gas springs 2FL, 2FR, 2RL, 2RR in order to stabilize the posture of the vehicle when the acceleration of the vehicle is relatively stable.

Next, in step 500, the correction total pressure calculation of each wheel is executed, and the sum of the pressure correction amounts for which the feedforward control and the feedback control have been calculated is calculated as the correction total pressure.

Next, based on the corrected total pressure obtained in step 600, the high pressure reserve switching valve 26,30, the leveling valve 42,44,46,48, and the discharge valve 58,60,6.
The drive duty for opening / closing the required valve among 4,66 is calculated and set.

Details of the feedforward control, the feedback control, the correction total pressure calculation of each wheel, and the valve control will be described.

FIG. 6 shows a flow chart of the feedforward control. First, in step 210, filtering processing of each signal is executed. That is, the data read this time is X
(N), the value after the previous filtering is Y (n-1),
If the filtering constant is If (= 1 to 256), the output Y (n) by filtering is expressed by the following equation.

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

Next, a series of determination processes are performed in order to detect the state of the attitude change factor of the vehicle. That is, in step 220, it is determined whether or not all the doors are closed by the vehicle door switch 94, and in step 230, the neutral switch 9
It is determined by 5 whether or not the transmission is in the neutral state, by step 240 it is determined by the throttle opening sensor 96 whether or not the throttle valve is fully closed, and at step 250, among the suspension control valves, Switching valve 26,30 for high pressure reserve, leveling valve 42,44,4
6,48, discharge valves 58,60,64,66 determine whether the vehicle height control of the suspension is being executed,
In step 260, the vehicle speed sensor 93 detects that the vehicle speed is the predetermined vehicle speed V0.
It is determined whether it is lower. Of these steps,
Steps 220, 230, 240, and 260 are factors that change the posture of the vehicle (door opening and closing to indicate passengers getting on and off, shift of the transmission indicating transmission of driving force to the tires, intake air amount to the internal combustion engine indicating driving force itself, vehicle speed indicating traveling condition). ) Of the gas springs 2FL, 2FR, 2RL, 2
This is a step of detecting that gas is not being supplied or discharged to adjust the atmospheric pressure of RR.

If all of these conditions are affirmative, it is predicted that the attitude of the vehicle is stable and there is no large pressure fluctuation in the gas springs 2FL, 2FR, 2RL, 2RR, and the atmospheric pressure is stable. Therefore, in step 270, the values of the respective pressure sensors 50, 52, 54, 56 at that time are set to the reference pressures PFLA, P.
It is stored in the RAM 106 as FRA, PRLA, and PRRA. The filtering constant If used in step 210 is set so that this pressure value has a lower frequency than the filtering in step 210, for example, a value filtered by a low-pass filter of 5 Hz.

If any one of the above steps 220 to 260 is negatively determined, the above step 270 is not executed and each reference pressure PF
LA, PFRA, PRLA and PRRA are not newly set. That is, as long as the conditions are met, the reference pressures PFLA and PFR are constantly
A, PRLA, PRRA will be updated.

Next, after the processing of step 270, or if one of the negative determinations is made in steps 220 to 260, in step 280, the lateral acceleration of the vehicle, RL, is calculated based on the map shown in FIG. , Vehicle speed V and steering angle θ. The graph corresponding to the map of FIG. 10 shows two broken lines only for two different predetermined accelerations, and the other has the same relationship, and therefore the description thereof is omitted. Of course, other acceleration values may be obtained by interpolation calculation.

Next, at step 290, the estimated lateral jerk of the vehicle Is calculated from the vehicle speed V and the steering angular velocity that is the differential value of the steering angle θ based on the map shown in FIG.
The steering angular velocity may be a difference between the steering angles θ within a predetermined period, that is, a difference value. The graph corresponding to the map in FIG. 11 shows only the cases of eight different steering angular velocities by eight polygonal lines, and the intervals are calculated by interpolation calculation.

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

Here, m and h represent constants, and have values appropriately determined by experiments or the like in order to predict the roll.

Next, at step 310, based on the map shown in FIG.
Using the above GRLM, each suspension 1FL, 1FR, 1RL, 1RR
Gas pressure 2FL, 2FR, 2RL, 2RR target pressure difference ΔPFLM, Δ
PFRM, ΔPRLM, and ΔPRRM are calculated. That is, the horizontal axis is the predicted acceleration GRLM [G] and the vertical axis is the target pressure difference [kgf
/ cm ² ], each target pressure difference ΔPFLM, ΔPFRM, ΔP
RLM and ΔPRRM are related as shown in the figure and are expressed as in the following equation.

ΔPFLM = aGRLM ΔPFRM = -aGRLM ΔPRLM = bGRLM ΔPRRM = -bGRLM where a and b are coefficients for correcting variations in various characteristics of the suspension and are expressed as in the following equation.

Where W is the sprung weight, 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, Ar 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. Further, Kf is an arbitrary value set in the range of (L / Lr)> Kf ≧ 0.1, and represents the frontal shared load increment. When Kf = 1.0, the frontal shared load is 50%. By arbitrarily setting this Kf, the steer characteristic of the vehicle can be arbitrarily set.

However, in order to prevent repeated minute adjustments due to fluctuations in calculated values, detection errors, noise, etc., -i ≤ GRLM
When ≦ i, ΔPFLM = ΔPFRM = ΔPRLM = ΔPRRM =
It is set to 0 and a dead zone is provided.

Next, at step 320, each target pressure PLFM, PFRM, PRLM, PRR
M is calculated as shown below.

PLFM = ΔPFLM + ΔPFLA PFRM = ΔPFRM + ΔPFRA PRLM = ΔPRLM + ΔPRLA PRRM = ΔPRRM + ΔPRRA With this, each control target pressure is determined.

Next, at step 330, the pressure deviations eFL, eFR, eRL, eRR are calculated as in the following equations.

eFL = PLFM-PFL eFR = PFRM-PFR eRL = PRLM-PRL eRR = PRRM-PRR where PFL, PFR, PRL, PRR are each suspension 1FL, 1F
This is a filtered value of the outputs of the pressure sensors 50, 52, 54, 56 provided in the main gas chambers 4FL, 4FR, 4RL, 4RR of R, 1RL, 1RR.

Next, in step 340, in order to convert each pressure deviation into a control manipulated variable, each feedforward gain k1 is changed to the 13th
It is determined according to the difference between the predicted acceleration GRLM and the actual lateral acceleration GRL based on the map shown by the dotted line in the figure. 1GRLM-GR
When L1 is q or less, k1 = 0, and when Q is Q or more, k1 = T,
In the meantime, the relationship is such that it increases as the 1GRLM-GRL1 increases. However, k2 and K3 represent gains of feedback control described later. That is, if the difference between the predicted lateral acceleration GRLM and the current lateral acceleration GRL is large,
It is shown that the contribution rate of the feedforward control to the actual control amount increases.

Next, at step 350, the gain k1 and each pressure deviation eF
Using L, eFR, eRL, eRR, feedforward pressure c1 to each suspension 1FL, 1FR, 1RL, 1RR as shown in the formula below.
FL, c1FR, c1RL, c1RR are calculated.

c1FL = k1eFL c1FR = k1eFR c1RL = k1eRL c1RR = k1eRR In this way, the feedforward calculation processing is performed and the feedforward pressure amounts c1FL, c1FR, c1RL, c1RR are calculated.

Next, the feedback calculation process shown in FIG. 7 is performed. First, in step 410, each suspension 1FL, 1F
According to the output values XFL, XFR, XRL, XRR of the vehicle height sensors 80, 82, 84, 86 provided in R, 1RL, 1RR, each displacement,
That is, the vertical displacement amount XH, the pitch displacement amount XP, the roll displacement amount XR, and the twist displacement amount XW of the vehicle body are calculated.

XH = (XFR + XFL) + (XRR + XRL) XP = (XFR + XFL)-(XRR + XRL) XR = (XFR-XFL) + (XRR-XRL) XW = (XFR-XFL)-(XRR-XRL) where XFR is the front wheel. The vehicle height on the right side, XFL is the vehicle height on the left side of the front wheels, XRR is the vehicle height on the right side of the rear wheels, and XRL is the vehicle height on the left side of the rear wheels.

Next, at step 420, the mode deviations eH, eP, eR, eW are calculated based on the displacement amounts XH, XP, XR, XW as shown in the following equations.

eH = XHM-XH eP = XPM-XP eR = XRM-XR eW = XWM-XW where XHM is the target vertical displacement amount, and based on the map shown in FIG. 14, the vehicle speed V and the vehicle height high switch 97 or It is determined from the mode (H-AUTO or N-AUTO) selected by the vehicle height low switch 98. XPM is a target pitch displacement amount, which is determined from the actual vehicle front-rear acceleration GFR detected by the acceleration sensor 92 based on the map shown in FIG. XRM is a target roll displacement amount and is determined from the same actual acceleration G RL in the lateral direction of the vehicle based on the map shown in FIG. XWM is the target torsional displacement amount, which is normally zero.

Next, at step 430, the mode speed deviations H, P, R, W are calculated according to the following equations based on the differential values H, P, R, W of the displacement amounts XH, XP, XR, XW. To be done. still,
H, P, R and W may be difference values of XH, XP, XR and XW for a predetermined period.

H = HM-HP = PM-PR = RM-RW = WM-W where HM is the target vertical displacement velocity amount, which is usually zero. PM is a target pitch velocity displacement amount, which is determined from the jerk FR in the vehicle longitudinal direction based on the map shown in FIG. RM is the target roll displacement velocity amount, which is determined from the jerk RL in the lateral direction of the vehicle based on the map shown in FIG. WM is the target torsional displacement velocity amount, which is usually zero.

Next, at step 440, in order to convert each deviation into a control manipulated variable, each feedback gain k2H, k2P, k2R, k2W (k2W
Collectively. ), And k3H, k3P, k3R, k3W (collectively referred to as k3) are obtained according to the difference between the predicted acceleration GRLM and the actual lateral acceleration GRL based on the map shown by the solid line in FIG. When 1GRLM-GRL1 is q or less, k2, k3 = T, and when it is Q or more, k2, k3 = t, and 1GRLM-GRL between them.
The relationship is such that it decreases with an increase of 1.
That is, if the difference between the predicted acceleration GRLM and the current lateral acceleration GRL is small, the contribution rate of the feedback control to the actual control amount becomes large.

Next, at step 450, the respective feedback amounts DH, DP, DR, DW are calculated from the above mode deviations eH, eP, eR, eW and the mode speed deviations H, P, R, W by the following equations. .

DH = k2H ・ eH + k3H ・ H + k4H DP = k2P ・ eP + k3P ・ P + k4P DR = k2R ・ eR + k3R ・ R + k4R DW = k2W ・ eW + k3W ・ W + k4W However, k4H, k4P, k4R, k4R, k4R, k4R, k4R, k4R are constants.

Next, at step 460, the feedback amounts DH, DP,
Based on DR, DW, each suspension 1FL, 1
The feedback amounts DFL, DFR, DRL, DRR of FR, 1RL, 1RR are calculated.

DFL = 1/4 (kOH ・ DH ＋ 2kOP ・ Lf ・ DP-kRR ・ DR-
kOW ・ DW) DFR = 1/4 (kOH ・ DH ＋ 2kOP ・ Lf ・ DP ＋ kRR ・ DR +
kOW ・ DW DRL = 1/4 (kOH ・ DH-2kOP ・ (1-Lf) ・ DP-kRR
・ DR + kOW ・ DW) DRR = 1/4 (kOH ・ DH-2kOP ・ (1-Lf) ・ DP + kRR
-DR-kOW-DW) Here, kOH, kOP, kRR, kOW represent a predetermined coefficient, and Lf represents a distribution coefficient between the front and rear wheels in consideration of the position of the center of gravity of the vehicle in the wheel base.

Next, at step 470, the feedback amount DFL, DF
Based on R, DRL, DRR, the respective feedback pressure amounts c2FL, c2FR, c2RL, c2RR are calculated by the following equations.

c2FL = PFL, a2FL, DFL c2FR = PFR, a2FR, DFR c2RL = PRL, a2RL, DRL c2RR = PRR, a2RR, DRR where PFL, PFR, PRL, PRR are each suspension 1FL, 1F
This is a filtered value of the outputs of the pressure sensors 50, 52, 54, 56 provided in the main gas chambers 4FL, 4FR, 4RL, 4RR of R, 1RL, 1RR. a2FL, a2FR, a2RL, a _RR is a predetermined coefficient.

In this way, the feedback calculation process is performed, and the feedback pressure amounts c2FL, c2FR, c2RL, c2RR are calculated.

Next, in step 510 shown in FIG. 8, a corrected total pressure calculation process is performed. That is, as shown in the following equation, the feedforward pressure amounts c1FL, c1FR, c1RL, c1RR calculated by the feedforward calculation process and the feedback pressure amounts c2FL, c2FR, c2RL, c2RR calculated by the feedback calculation process are calculated.
The corrected total pressure amounts cFL, cFR, cRL, cRR are calculated from the sum of the above.

cFL = c1FL + c2FL cFR = c1FR + c2FR cRL = c1RL + c2RL cRR = c1RR + c2RR Next, in the valve control process shown in FIG. Processing is done.

That is, in step 610, the switching valve for the high pressure reserve is adjusted by the following formula to adjust the pressure of the main gas chambers 4FL, 4FR, 4RL, 4RR based on the corrected total pressure amounts cFL, cFR, cRL, cRR calculated above. 26,30, valve on time tFL of leveling valve 42,44,46,48 or discharge valve 58,60,64,66
tFR, tRL, tRR are calculated.

High pressure reserve switching valve 26,30, leveling valve 42,
44,46,48 ON, that is, when pressure is increased tFL = (aF / φ) ・ (cFL / PFH) tFR = (aF / φ) ・ (cFR / PFH) tRL = (aR / φ) ・ (cRL / PRH) tRR = (aR / φ) ・ (cRR / PRH) Discharge valve 58,60,64,66 ON, that is, in case of pressure drop tFL = (bF / φ) ・ (cFL / PFL) tFR = (bF / φ) ・ (cFR / PFR) tRL = (bR / φ) ・ (cRL / PRL) tRR = (bR / φ) ・ (cRR / PRR) where aF / φ and aR / φ are shown in FIG. Based on the map, it is determined from the ratio P1 / P2 of the tank pressure P1 (= PFH or PRH) on the high pressure side and the main gas chamber pressure P2 supplied with gas from the high pressure tank. The high-pressure side tank is the high-pressure reserve tank 28,32 on the front wheel side or the rear wheel side.
Is the pressure in the high-pressure reserve tank 28 on the front wheel side, and PRH is the pressure in the high-pressure reserve tank 32 on the rear wheel side. bF / φ, bR / φ
Is calculated from the ratio P2 / P3 between the main gas pressure P2 and the tank pressure P2 on the low pressure side that receives the discharge of gas from the main gas chamber, based on the map shown in FIG. The low-pressure side tanks are the low-pressure reserve tanks 62 and 68 on the front wheel side or the rear wheel side.

Next, in the on-time correction calculation processing of step 620, the time at which the actual valve is driven (actual valve drive time) tFLU, tFRU based on the valve on-time tFL, tFR, tRL, tRR as shown below. , tRLU, tRRU (tFLD, tFRD, tRLD, tRRD) are calculated.

High pressure reserve switching valve 26,30, leveling valve 42,
44,46,48 ON, ie when pressure is increased tFLU = αF ・ tFL + βFL tFRU = αF ・ tFR + βFR tRLU = αR ・ tRL + βRL tRRU = αR ・ tRR + βRR Discharge valve 58,60,64,66 ON, ie when pressure is decreased tFLD = γF · tFL + δFL tFRD = γF · tFR + δFR tRLD = γR · tRL + δRL tRRD = γR · tRR + δRR where αF, γF, αR, γR, βFL, βFR, βRL, βR.
R, δFL, δFR, δRL, δRR represent predetermined coefficients.

Next, at step 630, the actual valve drive time tFLU, tFR
U, tRLU, tRRU (collectively referred to as tU), tFLD, tFRD, tRLD, tRRD
Guard processing (collectively referred to as tD) is performed. This is to prevent the valve from being turned on or off, or to switch from off to on for a very short time, and to protect the mechanism of the valve. That is, as shown in FIG.
When the actual valve drive time tU, tD that is less than 30% is calculated, the actual valve drive time tU, tD is set to zero, and the actual valve drive time tU, tD that exceeds 80% duty is calculated. , The actual valve drive time tU, tD is fixed to a time corresponding to a duty of 80%.

Next, in step 640, the drive duty representing the opening time of the valves 26, 30, 42, 44, 46, 48, 58, 60, 64, 66 is set by the actual valve drive times tU, tD guarded. .

In this way, when the air suspension control amount calculation process is once ended and the calculation process is started again after a predetermined period, a negative determination is made in step 103, and the process proceeds from step 110. After that, similar processing is repeated. In the present embodiment, the valve control cycle performed based on the calculated drive duty is 100 ms, and the valves 26, 30, 42, 44, 46,
The duty of 48, 58, 60, 64, 66 is controlled during this 100 ms. That is, as shown in FIG. 29, step 64 described above is performed.
Valves 26,30,42,44,46,48,58,6 every 100 ms according to the newest value of the actual valve drive time obtained at 0.
The duty of 0, 64, 66 is controlled for 100 ms.

In the present embodiment, as described above, the target pressures PFLM, PFRM, PRLM, PRRM are repeatedly calculated at sufficiently short times, and the suspensions 1FL, 1FR, 1FR, 1FR, Since the pressure in the main gas chambers 4FL, 4FR, 4RL, 4RR of 1RL, 1RR is adjusted, smooth pressure control corresponding to the actual roll change becomes possible. Therefore, the driver's discomfort is eliminated, and high steering stability can be obtained.

That is, when steering as shown in FIG. 22 (A), (B)
As shown in, the predicted acceleration GRLM (two-dot chain line) in the lateral direction rises early and a difference from the actual acceleration GRL (solid line) occurs. In this embodiment, as shown in (C), the valve drive signal is output in a predetermined cycle (for example, 100 ms) according to the calculated target pressure value. Therefore, as shown in (D), each gas chamber 4FL, 4FR, 4R of suspension 1FL, 1FR, 1RL, 1RR
Since the pressures of L and 4RR gradually increase stepwise in accordance with the degree of increase in the predicted acceleration GRLM, the roll angle can be kept extremely small as shown in (E). In this way, the vehicle is stable and the steering stability is also improved.

On the other hand, when the pressure is adjusted at once (dotted line) in anticipation of the increase in lateral acceleration as in the conventional example shown in (C),
As shown in (D), the pressure rises at once, ignoring the rise in lateral acceleration. Therefore, an extremely large reverse roll is generated as shown in (E). Therefore, the driver may feel uncomfortable and the steering stability may be impaired.

Further, in the present embodiment, in addition to the lateral acceleration RL of the vehicle, the lateral jerk of the vehicle is estimated. Since the predicted acceleration GRLM is calculated, the attitude control can be started immediately before the attitude change of the vehicle, and more accurate feedforward control can be performed. Of course, the estimated acceleration RL
Only or estimated jerk The predicted acceleration GRLM may be calculated by only the above. Also,
Estimated acceleration RL or estimated jerk Alternatively, in calculating the predicted acceleration GRLM, the actual acceleration GRL or its differential value or the actual jerk RL which is a difference value for a predetermined period may be used.

In the above embodiment, the steps of the feedforward calculation process
At 280,290, the estimated lateral acceleration RL of the vehicle is 10th
An estimated jerk in the lateral direction of the vehicle, which is obtained from the vehicle speed V and the steering angle θ based on the map shown in the figure. Is obtained from the vehicle speed V and the steering angular velocity on the basis of the map shown in FIG. 11. However, when the acceleration in the front-rear direction is captured instead of the lateral acceleration, it becomes a measure for the pitch.
That is, as shown in FIG. 23, the vehicle speed V and the throttle opening θ
The estimated longitudinal acceleration FR of the vehicle is calculated from TH and
As shown in the figure, the estimated jerk in the longitudinal direction of the vehicle is calculated from the vehicle speed V and the throttle opening speed TH. And the predicted acceleration GFRM may be calculated from both in the same manner. This will help prevent squats on the pitch. Throttle opening θTH and throttle opening speed
TH is detected by a throttle opening sensor 96 which outputs a signal corresponding to the opening of the throttle valve of an internal combustion engine (not shown) to the electronic control circuit 100.

Further, as another countermeasure against squat, using the rotational speed N of the internal combustion engine instead of the vehicle speed V, as shown in FIG. 25, the estimated acceleration FR in the longitudinal direction of the vehicle is obtained from the rotational speed N and the throttle opening θTH. , As shown in FIG. 26, the rotation speed N
Estimated jerk in the front-back direction of the vehicle from and the throttle opening speed TH And the predicted acceleration G in the front-rear direction from both sides in the same manner.
The FRM may be calculated. The rotation speed is detected by a rotation speed sensor (not shown) that outputs a signal corresponding to the rotation speed of the crankshaft of the internal combustion engine to the electronic control circuit 100.

Further, as a measure against the dive in the pitch, instead of the throttle valve opening θTH and the opening speed TH, the brake depression amount θBR and the depression speed BR thereof are used.
As shown in the figure, the estimated acceleration FR in the front-rear direction of the vehicle is obtained from the vehicle speed V and the brake depression amount θBR, and as shown in FIG. 28, the estimated acceleration in the front-rear direction of the vehicle is estimated from the vehicle speed V and the brake depression speed BR. acceleration And the predicted acceleration GFRM may be calculated from both in the same manner. The brake depression amount θBR and its depression speed BR 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).

The predicted acceleration GFRM obtained by the countermeasures against the squat and the dive is independently used for the suspension control and is useful for preventing each of the squat and the dive, but the predicted acceleration GFRM can also be used in combination. Well, multiple measures are possible. As a result, similarly to the case of the roll, even if the squat or the dive is not excessively controlled at the initial stage, smooth suspension control becomes possible and high steering stability can be realized. Furthermore, the predicted acceleration GRL obtained by roll measures
M may be combined with each of the above-described predicted accelerations GFRM, and both roll measures and pitch measures can be executed.

In the above embodiment, the suspensions 1FL, 1FR, 1RL,
1RR corresponds to fluid actuator M2, vehicle height sensor 80,
82,84,86, steering angle sensor 90, acceleration sensor 92, vehicle speed sensor 93, door switch 94, neutral switch 95, throttle opening sensor 96, vehicle height high switch 97, vehicle height low switch 98, rotation speed sensor and brake The depression amount detection sensor corresponds to the vehicle traveling state detection means M3, and the electronic control circuit 100 causes the target correction pressure amount calculation means M4 and the supply / discharge control means M5.
Steps 280, 290, 300, 310, 320, 330 correspond to the processing as the target correction pressure amount calculating means M4,
The processing of 610, 620, 630, 640 and FIG. 29 corresponds to the processing as the supply / discharge control means M5.

[Brief description of drawings]

1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram of one embodiment of an electronically controlled suspension device, FIG. 3 is an air circuit diagram of this embodiment, and FIG. 4 is an electrical diagram of this embodiment. FIG. 5 is a block diagram showing the configuration of the system, and FIG. 5 is a general flowchart of a control routine executed by the electronic control circuit of this embodiment.
FIG. 6 is a flow chart of feed-forward calculation processing therein, FIG. 7 is a flow chart of feedback calculation processing therein, FIG. 8 is a flow chart of corrected total pressure calculation processing therein, and FIG. 9 is valve control amount calculation. FIG. 10 is a graph showing a map for obtaining the estimated lateral acceleration RL from the steering angle θ and the vehicle speed V, and FIG. 11 is the estimated lateral jerk from the steering angular velocity and the vehicle speed V. Fig. 12 is a graph showing the map for obtaining the predicted acceleration GRL
Target pressure difference from M ΔPFLM, ΔPFRM, ΔPRLM, ΔPRRM
Fig. 13 is a graph showing a map for calculating the predicted acceleration GRL
A graph showing a map for obtaining the feedforward gain k1 and the feedback gains k2, k3 based on the difference between M and the actual lateral acceleration GRL, and FIG. 14 is a graph corresponding to the map for obtaining the target vehicle height based on the vehicle speed V and the mode. , FIG. 15 is a graph corresponding to the map for obtaining the target pitch displacement XPM based on the actual longitudinal acceleration GFR, FIG. 16 is a graph corresponding to the map for obtaining the target roll displacement XRM based on the actual lateral acceleration GRL, FIG. Is a graph corresponding to the map for obtaining the target pitch displacement velocity PM based on the actual longitudinal acceleration GFR, and FIG. 18 is the target roll displacement velocity RM based on the actual lateral jerk RL.
19 is a graph corresponding to the map for obtaining the coefficient aF / φ, aR / based on the ratio P1 / P2 between the tank pressure P1 on the high pressure side and the main gas chamber pressure P2 supplied with gas from the high pressure tank.
A graph corresponding to the map for obtaining φ, Fig. 20 shows the coefficient bF / φ, bR based on the ratio P2 / P3 between the main gas chamber pressure P2 and the low-pressure side tank pressure P3 that receives the discharge of gas from the main gas chamber. /
FIG. 21 is a graph corresponding to a map for obtaining φ, FIG. 21 is a graph corresponding to a map for obtaining an output duty based on the actual valve drive times tU, tD, FIG. 22 is a timing chart showing the effect of the embodiment, and FIG. Throttle opening θTH and vehicle speed V
Fig. 24 is a graph showing a map for obtaining the estimated longitudinal acceleration FR from, and Fig. 24 shows the estimated longitudinal jerk based on the throttle opening TH and the vehicle speed V. FIG. 25 is a graph showing a map for obtaining the estimated longitudinal acceleration FR from throttle opening θTH and internal combustion engine rotation speed N, and FIG. 26 is a throttle opening speed.
Estimated longitudinal jerk from TH and internal combustion engine speed N 27 is a graph showing a map for obtaining the estimated longitudinal acceleration FR from the brake depression amount θBR and the vehicle speed V, and FIG. 28 is a brake depression speed BR.
And jerk estimated from vehicle speed V FIG. 29 is a graph showing a map for obtaining the value of FIG. M1 …… Wheels M2 …… Fluid actuator M3 …… Vehicle running state detection means M4 …… Target correction pressure amount calculation means M5 …… Supply / discharge control means M6 …… High pressure reserve tank M7 …… Low pressure reserve tank M8 …… ON / Off control valve 1FL, 1FR, 1RL, 1RR …… Suspension 2FL, 2FR, 2RL, 2RR …… Gas spring 26,30 …… Switch valve for high pressure reserve 34,36,50,52,54,56,70,72… … Pressure sensor 42,44,46,48 …… Leveling valve 58,60,64,66 …… Discharge valve 80,82,84,86 …… Vehicle height sensor 90 …… Steering angle sensor, 92 …… Acceleration sensor 93 …… Vehicle speed sensor 94 …… Door switch 95 …… Neutral switch 96 …… Throttle opening sensor 100 …… Electronic control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Yutani, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor: Osamu Takeda 1, Toyota Town, Aichi Prefecture Toyota Motor Co., Ltd. ( 72) Inventor Shunichi Doi 1 1st 41st Yokomichi, Nagakute-cho, Nagakute-cho, Aichi-gun, Toyota Central Research Institute Co., Ltd. (56) Reference JP 62-96114 (JP, A) JP 62-103212 JP, A) JP 61-150809 (JP, A) JP 60-229815 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A vehicle running state detecting means for detecting a running state of a vehicle, and a control cycle of a fluid actuator of a suspension provided on a wheel of the vehicle based on the running state of the vehicle detected by the vehicle running state detecting means. A target correction that predicts the acceleration of the vehicle that will reach the above and calculates a target correction pressure amount of the pressure in the fluid actuator based on the acceleration so as to suppress the change in the vehicle attitude caused by the acceleration. Depending on the pressure amount calculation means and the target correction pressure amount calculated by the target correction pressure amount calculation means, the fluid supply / discharge control of the fluid in the fluid actuator is executed at a cycle longer than the calculation cycle of the target correction pressure quantity. An electronically controlled suspension device for adjusting the attitude of a vehicle, comprising: In addition, the supply / discharge control means controls the supply / discharge of the fluid by duty control of an on / off control valve arranged between the fluid actuator and the high-pressure reserve tank and the low-pressure reserve tank of the compressible fluid. The vehicle traveling state detecting means detects a parameter relating to a vehicle speed and a parameter relating to a vehicle operation for causing an acceleration change in the vehicle, and the target correction pressure amount computing means calculates the vehicle based on the detected parameter. An electronically controlled suspension device, characterized in that the acceleration and jerk of the vehicle are estimated, and the acceleration of the vehicle is predicted from the estimated acceleration and jerk.