JPH0672122A - Electronically controlled suspension system - Google Patents

Abstract

PURPOSE:To turn a vehicle smoothly by reducing the oversteering trend of the vehicle turning and travelling while being braked. CONSTITUTION:A suspension system is composed of a braked condition detecting means 46 for detecting the braked condition of a vehicle, a roll control amount distribution correction means 36 for correctively increasing the front wheel side roll control amount more than the rear wheel side roll control amount when the braked condition of the vehicle is detected by the braked condition detecting means, a rear wheel steering means for steering the rear wheel and a rear wheel steering control means 55 for controllably increasing the rear wheel in-phase steering angle amount by the rear wheel steering means when the braked vehicle is detected by the braked condition detecting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled suspension device having a four-wheel steering function.

[0002]

2. Description of the Related Art When a vehicle brakes, the ground contact load of the front wheels increases and the ground contact load of the rear wheels decreases, so that the grip force of the rear wheels decreases. Therefore, when the vehicle turns while braking, the steering of the vehicle oversteers.

[0003]

That is, when the vehicle turns while braking, the turning characteristic of the vehicle tends to oversteer. For this reason, when the driver turns the steering wheel in a normal manner, the steering wheel is forced to be returned and the steering wheel operation is not smooth.

The present invention has been made in view of the above points, and an object thereof is to provide an electronically controlled suspension device capable of smoothly turning by reducing the tendency of the vehicle to oversteer when the vehicle is turning while braking. To provide.

[0005]

SUMMARY OF THE INVENTION An electronically controlled suspension system according to the present invention comprises a roll detecting means for detecting a factor causing a roll on a vehicle body, and a support force for the vehicle body for each wheel so as to be independently adjustable. An electronic device including a suspension unit provided with a fluid chamber and control means for changing the supporting force of the left and right suspension units by a roll control amount according to the detection output of the roll detection means so as to suppress the roll of the vehicle body. In the control suspension control device, braking state detection means for detecting the braking state of the vehicle,

When the braking state of the vehicle is detected by the braking state detecting means, the roll control amount distribution correcting means for correcting the roll control amount of the front wheels so as to be larger than the roll control amount of the rear wheels. And rear wheel steering means for steering the rear wheels,

When the braking state detecting means detects the braking of the vehicle, the rear wheel steering control means controls the rear wheel steering means to increase the in-phase steering angle amount of the rear wheels.

[0008]

If the braking of the vehicle is detected by the braking state detecting means, the supply / exhaust correction coefficients of the front wheels and the rear wheels are obtained in order to control the roll distribution in accordance with the braking. Then, with respect to the distribution during the roll control of the electronically controlled suspension by the supply / exhaust correction coefficient, the front wheels are increased to make the steering characteristic of the vehicle understeer, and the in-phase steering amount is slightly increased with respect to the rear wheel steering amount of the four-wheel steering. As a result, the center-of-gravity slip angle is reduced, and oversteer during braking turn is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an electronically controlled suspension device according to an embodiment of the present invention, FIG. 2 is a diagram showing a configuration of a four-wheel steering system according to the same embodiment, and FIG. 3 is a three-way valve driving / non-driving state. FIG. 4, FIG. 4 is a diagram showing driving and non-driving states of a solenoid valve, FIG. 5 is a diagram showing driving and non-driving states of a supply air flow control valve, FIG. 6 is a vehicle speed-steering wheel angular velocity map in SOFT mode, and FIG. Is a vehicle speed-steering wheel angular velocity map in AUTO mode, FIG. 8 is a vehicle speed-steering wheel angular velocity map in SPORT mode, FIG. 9 is a G sensor map, FIG. 10 is a diagram showing the relationship between control level and air supply / exhaust time by the vehicle speed-steering wheel angular velocity map, and FIG. 11 is The figure which shows the relationship between the control level and air supply / exhaust time by G sensor map,
FIG. 12 is a schematic flow chart showing the operation of one embodiment of the present invention, FIGS. 13 to 17 are detailed flow charts of a roll control routine, FIGS. 18 to 20 are flow charts showing a supply / exhaust correction routine, and FIGS. 21 and 22. 23 is a flowchart showing a supply / exhaust correction routine, FIG. 23 and FIG.
25 is a flowchart showing a rear steering angle determination routine, FIG.
Is the front wheel supply / exhaust gas distribution coefficient KTAF, rear wheel supply / exhaust gas distribution coefficient KTA
FIG. 26 is a diagram showing the road surface slope value characteristic of R, FIG. 26 is a diagram showing the vehicle speed characteristic of the in-phase coefficient K1, FIG. 27 is a diagram showing the vehicle speed characteristic of the momentary anti-phase coefficient K2, and FIG. 28 is a map for determining the acceleration / deceleration state of the vehicle. 29 shows a momentary reverse phase magnification KG2-calculated lateral G characteristic, FIG. 30 shows rear wheel steering angle distribution Δδr-front and rear G characteristic, and FIG. 31 shows front wheel supply / exhaust gas distribution coefficient KXGF, rear wheel supply / exhaust gas distribution. FIG. 32 is a diagram showing the front-rear G characteristic of the coefficient KTGR, and FIG. 32 is a diagram showing the front-rear G and yaw angular velocity characteristics during braking and acceleration.

In the figure, FS1 is a left front wheel side suspension unit, FS2 is a right front wheel side suspension unit, RS1 is a left rear wheel side suspension unit,
RS2 is a suspension unit on the right rear wheel side. Each of these suspension units FS1, FS2, RS
Since 1 and RS2 have the same structure as each other,
The suspension unit will be described with reference numeral S, except for the case of distinguishing between the front wheels and the rear wheels or the left wheels and the right wheels.

The suspension unit S has a shock absorber 1. The shock absorber 1 includes a cylinder mounted on the wheel side, and a piston rod 2 having a piston fitted in the cylinder so as to be swingable and having an upper end supported on the vehicle body side. Also,
The suspension unit S includes an air spring chamber 3 having a function of adjusting a vehicle height, which is coaxial with the piston rod 2 and is provided above the shock absorber 1. A part of the air spring chamber 3 is formed by a bellows 4, and air is supplied to and discharged from the air spring chamber 3 through a passage 2a provided in the piston rod 2 to raise or lower the vehicle height. Can be lowered.

Further, inside the piston rod 2, a control rod 5 having a valve 5a for adjusting a damping force at its lower end is arranged. The control rod 5 is rotated by an actuator 6 attached to the upper end of the piston rod 2 to drive the valve 5a. By the rotation of the valve 5a, the damping force of the suspension unit is set to three levels of hard (hard), medium (medium), and soft (soft).

The compressor 11 compresses the air taken in from the air cleaner 12 and sends it to the high pressure reserve tank 15a via the dryer 13 and the check valve 14. In other words, the compressor 11 compresses the air taken in from the air cleaner 12 and supplies the compressed air to the dryer 13, so that the compressed air dried by silica gel or the like in the dryer 13 is stored in the high pressure reserve tank 15a. The compressor 16 has a suction port at a low pressure reserve tank 15b and a discharge port at a high pressure reserve tank 1b.
5a, respectively. Reference numeral 18 denotes a pressure switch which is turned on when the pressure in the low pressure reserve tank 15b becomes equal to or higher than a first set value (for example, atmospheric pressure). When the compressor 16 outputs an ON signal of the pressure switch 18, the compressor 16 is driven by a compressor relay 17 which is turned on by a signal from a control unit 36 described later. As a result, the pressure in the low pressure reserve tank 15b is always kept below the first set value.

The air is supplied from the high pressure reserve tank 15a to each suspension unit S as shown by the solid line arrow in FIG. That is, the compressed air in the high pressure reserve tank 15a is supplied with the air supply flow rate control valve 19, the front air supply solenoid valve 20, and the check valve 2.
1, the front left solenoid valve 22 and the front right solenoid valve 23 to feed the suspension units FS1 and FS2. Similarly, the compressed air in the high pressure reserve tank 15a is supplied to the supply air flow control valve 1
9. The suspension unit R via the rear air supply solenoid valve 24, the check valve 25, the rear left solenoid valve 26, and the rear right solenoid valve 27.
It is sent to S1 and RS2.

On the other hand, the exhaust from each suspension unit S is performed as shown by the broken line arrow in FIG. That is,
Compressed air in the suspension units FS1 and FS2 is supplied to the low pressure reserve tank 1 via the exhaust direction switching valve 28 including solenoid valves 22 and 23 and a three-way valve.
5b and the solenoid valves 22 and 2
3, exhaust direction switching valve 28, check valve 29,
It may be discharged to the atmosphere via the dryer 13, the exhaust solenoid valve 31, the check valve 46, and the air cleaner 12. Similarly, suspension unit RS
Compressed air in RS1, RS2 is solenoid valve 26,2
7. When the fuel is fed into the low pressure reserve tank 15b through the exhaust direction switching valve 32, and when the solenoid valve 2 is used.
6, 27, the exhaust direction switching valve 32, the check valve 33, the dryer 13, the exhaust solenoid valve 31, the check valve 46, and the air cleaner 12 may be discharged to the atmosphere. Check valves 29 and 3
Exhaust direction switching valve 2 between 3 and dryer 13
A passage in which a small-diameter throttle L is interposed is provided as compared with a passage that directly connects the low pressure reserve tank 15b and the low pressure reserve tank 15b.

The solenoid valves 22 and 2 described above
As shown in FIGS. 3 (A) and 3 (B), 3, 26, 27, 28, and 32 indicate that air flows as indicated by arrow A when ON (energized state) and arrow B when OFF (non-energized). Such air circulation is permitted. Further, the air supply solenoid valves 20 and 24 and the exhaust solenoid valve 31 are shown in FIG.
As shown in (B) and (B), the flow of air as indicated by the arrow C is permitted when ON (energized state), and the flow of air is prohibited when OFF (non-energized state). Further, in the off state (non-energized) of the supply air flow rate control valve 19, air flows through the orifice o as shown in FIG. 5 (A), so that the air flow rate is small, and in the on state (energized) of FIG. Since air circulates through the orifice o and the large diameter path D as shown in B), the air flow rate increases.

The reference numeral 34F designates a front vehicle height sensor which is mounted between the lower arm 35 of the front right suspension of the vehicle and the vehicle body to detect the front vehicle height, and 34R designates the vehicle body and the lateral rod 37 of the rear left suspension portion of the vehicle. It is a rear vehicle height sensor that is mounted in between and detects the rear vehicle height. The signals detected by the vehicle height sensors 34F and 34R are supplied to a control unit 36 including an input circuit, an output circuit, a memory and a microcomputer.

Reference numeral 38 denotes a vehicle speed sensor incorporated in the speedometer, which supplies the detected vehicle speed signal to the control unit 36. Reference numeral 39a is an acceleration sensor for detecting a lateral acceleration G acting on the vehicle body, and 39b is an acceleration sensor for detecting a longitudinal acceleration acting on the vehicle body, that is, a longitudinal G, and the detected acceleration signal is sent to the control unit 36. Supplied. 30 is a roll control mode of software (SOFT), auto (AUTO), sports (SPORT
A roll control mode selection switch selected in S), and a steering sensor 40 for detecting the rotation speed of the steering wheel 41, that is, the steering angular speed. Reference numeral 42 is a throttle opening sensor (not shown) for detecting the throttle opening THV of the engine. These roll control selection switches 30,
The signals detected by the sensors 40 and 42 are supplied to the control unit 36. Reference numeral 43 is a compressor relay for driving the compressor 11, and the compressor relay 43 is controlled by a control signal from the control unit 36. 44 is a high pressure reserve tank 15
The pressure inside a is the second set value (for example, 7 kg / cm ² ) It is a pressure switch that is turned on when the following is reached, and the signal of this pressure switch 44 is supplied to the control unit 36. Then, when the pressure in the high-pressure reserve tank 15a becomes equal to or lower than the second set value and the pressure switch 44 is on, the control unit 36 turns on the pressure switch 18, that is, when the compressor 16 is driven, It is configured to prohibit the driving of the compressor 11. Reference numeral 45 is a pressure sensor provided in a passage that connects the solenoid valves 26 and 27 to each other, and detects the internal pressure of the rear suspension units RS1 and RS2. Reference numeral 46 is a brake switch that outputs an ON signal when a brake pedal (not shown) is depressed, and the detection signal of this brake switch 46 is the control unit 3
6 is output.

The solenoid valves 19 and 2 described above are used.
0, 22, 23, 24, 26, 27, 28, 31 and 3
The control of No. 2 is performed by a control signal from the control unit 36.

By the way, the rotation of the steering wheel 41 is transmitted via the steering shaft 51 to the power steering device 52 as a front wheel steering actuator for steering the front wheels. This power steering device 52
Is the pressure PL in the left and right pressure chambers of the front wheel steering actuator.
, PR are provided with pressure sensors 53 and 54, respectively. The pressure difference between the pressure chambers is obtained as the power steering pressure by the sensor signals from the pressure sensors 53 and 54.

The pressures PL, PR in the left and right pressure chambers detected by the pressure sensors 53, 54 described above are output to a 4WS ECU (electric control unit) 55 for steering control of the rear wheels. The ECU 55 is composed of a microcomputer and its peripheral circuits. The ECU 55 and the control unit 36 are connected by a communication line L, and the steering wheel angular velocity θH ′ detected by the steering sensor 40, the steering wheel angle θH detected by a steering wheel angle sensor (not shown), and the throttle opening sensor 42 are detected. The throttle opening THV, the detection signal of the brake switch 46, the vehicle speed V detected by the vehicle speed sensor 38
Is transmitted from the control unit 36 to the 4WS ECU 55.

The ECU 55 calculates the power steering pressure ΔP (= PR-PL) from the pressures PL and PR of the left and right pressure chambers detected by the pressure sensors 53 and 54, and the power steering pressure Δ
The road surface μ is calculated from P, the steering wheel angle θH and the vehicle speed V.
Then, the RMU value as the road surface μ value is output to the control unit 36 described above.

Further, the 4WS ECU 55 determines a rear wheel steering angle command value δr with respect to the steering angle of the front wheels, outputs a drive signal to a control valve for driving a rear wheel steering power cylinder, which will be described later, and outputs the rear wheels to the rear wheels. The control for steering by the steering command value δr is performed. The rear wheel steering angle command value δr will be described later with reference to FIG.
And EC by the control of the 4WS control routine shown in FIG.
Calculated as U55. This ECU 55 uses the acceleration flag ACFLG and the braking flag set in this 4WS control routine.
The CSFLG is output to the control unit 36. In addition,
The acceleration flag ACFLG is "1" when the acceleration state is detected.
Is set, and the braking flag CSFLG is set to "1" when a braking state is detected.

Reference numeral 56 is an A / T for performing shift control of the gear stage of an A / T (automatic transmission).
It is the control ECU 56. The ECU 56 is composed of a microcomputer and its peripheral circuits. The ECU 56 has a road surface gradient calculating means for calculating a road surface gradient on which the vehicle travels, that is, a road surface gradient value RK. The road surface gradient calculating means calculates the vehicle body mass (dynamic mass) m at that time from the engine output F and the acceleration a obtained by differentiating the vehicle speed V by the following equation. F = ma (1)

This vehicle body mass is calculated and output as RK of the equation (2) indicating the gradient data, assuming that the relationship of the following equation is satisfied with respect to the static mass m0 of the vehicle body model stored in advance. It has become so. m = m0 (1 + RK) (2) This road surface gradient value RK is output to the control unit 36. In the configuration of FIG. 1 described above, the illustration of the control mechanism for steering the four wheels, particularly for steering the rear wheels, is omitted.
The configuration will be described with reference to FIG.

In FIG. 2, 61FL is a left front wheel, 61FR is a right front wheel, 61RL is a left rear wheel, and 61RR is a right rear wheel. The left front wheel 61FL and the right front wheel 61FR are attached to the ends of the links 62 and 63 taken out from both sides of the power steering device 52.

Reference numeral 64 is a reserve tank for storing hydraulic oil. The reserve tank 64 is provided with oil pumps 67 for power steering via oil passages 65 and 66, respectively.
They are connected to the suction side of the 4WS oil pump 68, respectively. The high pressure side of the oil pump 67 is the oil passage 6
8, connected to the reserve tank 64 via a rotary valve provided on the input shaft 69.

The high pressure side of the oil pump 68 is connected to the A port of the 4-port throttle electromagnetic switching valve 71 via the unload valve 70. The P port of the electromagnetic switching valve 71 is connected to the right chamber 73R of the power cylinder 73 via the oil passage 72, and the R port of the electromagnetic switching valve 71 is connected to the oil passage 7R.
4 is connected to the left chamber 73L of the power cylinder 73.

In the power cylinder 73, the piston 7
5 is slidably inserted, and the left rear wheel 61RL and the right rear wheel 61RR are mounted on the piston rods 75R and 75L attached to both sides of the piston 75 via joint members arranged in the middle thereof. Are linked to. Then, the solenoids a and b of the electromagnetic switching valve 71 are connected to the 4WS ECU 5
The drive signal from 5 is input. A steering wheel angle sensor 76 detects the steering angle of the steering wheel 77.

Next, the operation of the embodiment of the present invention constructed as above will be described. FIG. 12 is a flowchart schematically showing a series of roll controls performed by the control unit 36. First, in a rough road determination routine (step A1) as a rough road determination means, so-called rough road determination processing is performed. That is, in this rough road determination routine, when the output change of the front vehicle height sensor 34F is equal to or higher than MHz (N times or more in 2 seconds), the dead zone of the G sensor 39 at this time is widened to determine the rough road, and roll control is performed. Reduced erroneous operation. In the roll control routine (step A2) as the roll control means, roll control is performed, that is, air is supplied to the suspension unit on the contraction side and exhausted from the suspension unit on the expansion side to prevent the roll of the vehicle body during turning. ing. Further, the air supply / exhaust time during the roll control is corrected in the air supply / exhaust correction routine (step A3) as the air supply / exhaust time correction means, and the air supply / exhaust time of the four wheels is corrected.
Further, in the damping force switching routine (step A4) as the damping force switching means, the damping force of each suspension unit is set to the optimum one of hard (hard), medium (medium) and soft (soft). It

Next, the detailed operation of the roll control routine (step A2) will be described with reference to the flowcharts of FIGS. First, the vehicle speed V detected by the vehicle speed sensor 38, the lateral acceleration G output from the G sensor 39 and its differential value G ′, and the steering wheel angular velocity Θ H ′ detected by the steering sensor 40 are the control unit 36.
Is read (steps C1 to C3). Then, it is determined whether the steering wheel angular velocity Θ H ′ is larger than 30 deg / sec (step C4). That is, it is determined whether the steering wheel is steered. If "YES" is determined in the above step C4, it is determined whether "G × ΘH '" is positive (step C5). That is, it is determined whether the acceleration G in the left-right direction and the steering wheel angular velocity Θ H ′ are in the same direction.
If it is determined that the steering wheel is steered, the steering wheel is steered to the turning side and if it is determined to be "negative". When it is determined to be "YES" in step C5, one of the V-? H 'maps shown in Figs. 6 to 8 which is selected according to the user's preference is referred to and the vehicle speed and the steering wheel angular velocity are set. A corresponding control level TCH is obtained (step C6). In this step C6, when the roll control selection switch 30 selects the soft mode as the roll control mode, the map of FIG. 6 is displayed, and when the roll control mode is selected as the auto mode, the map of FIG. When the sports mode is selected as the roll control mode, the map of FIG. 8 is selected. Then, the supply / exhaust time and the damping force as shown in FIG. 10 are selected corresponding to the control level TCH of each map. The relationships among the steering wheel angular velocity Θ H ′, the vehicle speed V, the control level, the mode, the supply / exhaust time and the damping force shown in FIGS. 6 to 8 and 10 are stored in the memory in the control unit 36. Then, by the supply / exhaust correction routine, which will be described in detail later with reference to FIGS. 18 to 20, the front / rear wheel independent supply / exhaust times TCSF, TCSR, TCEF,
TCER is corrected and calculated (step C7). Next, it is determined whether the control flag is being set or distortion (step C8). Since roll control has not started yet,
It is determined to be "NO" and the process proceeds to step C9. In step C9, it is determined whether the air supply / exhaust flag SEF is set. When the supply / exhaust flag SEF is set in the supply / exhaust correction routine (step C7), the control flag is set, and the supply / exhaust timer T is set.
= 0 (steps C10 and C11). Then, the routine proceeds to step C12, where it is judged whether or not the differential pressure is being held, that is, whether or not the differential pressure holding flag described later is set. When there is a differential pressure, the front and rear exhaust direction switching valves 28 and 32 are turned off so that the air discharged from the front or rear is discharged to the low pressure reserve tank 15b. This is because the exhaust direction switching valves 28 and 32 are on while the differential pressure is being held, and therefore it is necessary to turn off these exhaust direction switching valves 28 and 32 in order to perform additional supply / exhaust control. is there. next,
In the air supply / exhaust correction routine in step C7, it is determined whether the air supply coefficient KS = 3 is set (step C14), and if it is not set (that is, KS =).
In 1), the supply air flow rate control valve 19 is turned on to open the large path D (FIG. 5) to increase the supply air flow rate (step S15). In other words, KS = 1 is the case where the control level TCH is obtained from the vehicle speed-steering wheel angular velocity map as shown in FIG. 10, so that the air flow rate is increased in order to perform swift roll control.

Next, the front and rear air supply valves 20,
24 is turned on (step C16). Then, the direction of the acceleration G in the left-right direction is determined by the control unit 36 (step C17). That is, it is determined whether the direction of the acceleration G in the left-right direction is positive or negative. Here, when the acceleration G is positive, the acceleration G is on the right side in the traveling direction,
That is, it is determined that the vehicle is making a left turn. On the other hand, when the acceleration G is negative, it is determined that the acceleration G is a left turn in the traveling direction, that is, a right turn. Therefore, when the acceleration G is determined to be right (left turn), the front and rear left solenoid valves 22 and 26 are turned on (step C18). As a result, the air in each air spring chamber 3 of the left suspension unit is discharged into the low pressure reserve tank 15b via the valves 22 and 26 which are in the ON state, and at the same time, each air spring chamber 3 of the right suspension unit is discharged. Air supply valves 20 and 2 that are in the on state
Air is supplied from the high pressure reserve tank 15a through the valve 4 and the valves 23 and 27 in the off state.

On the other hand, when it is determined that the acceleration G is on the left side (right turn), the front and rear right solenoid valves 2
3, 27 are turned on (step C19). As a result, the air in the air spring chambers 3 of the right suspension unit is discharged into the low pressure reserve tank 15b via the valves 23 and 27 which are in the on state, and the air spring chambers 3 of the left suspension unit are also discharged. Air is supplied from the high-pressure reserve tank 15a through the air supply valves 20 and 24 in the on state and the valves 22 and 26 in the off state, respectively.

Next, the swing back flag is reset, the differential pressure holding flag is set, and the duty timer TD, the duty counter Tn, and the duty time counter Tmn are set to zero (steps C20 to C24).
Hereinafter, the process returns to step C1. Then, after the processes of steps C1 to C7, the process moves to step C8.
At this time, since the control flag is being set, it is determined to be "YES" in step C8 and the process proceeds to step C25.

Then, in step C25, the timer T is updated by adding the interval time INT. Then, until the count value of the timer T becomes equal to or more than the front wheel air supply time TCSF or the count value of the timer T becomes equal to or more than the front wheel exhaust time TCEF, the air spring chambers of the left and right suspension units of the front wheels are changed according to the direction of the left and right G. Roll control for air supply and exhaust is continuously performed.

Further, the count value of the timer T is equal to or larger than the rear wheel air supply time TCSR or the count value of the timer T is equal to the rear wheel exhaust time TCSR.
Until CER or higher, the roll control for supplying and exhausting air to and from the air spring chambers of the left and right suspension units of the rear wheels is continuously performed according to the direction of left and right G.

By the way, when the count value of the timer T becomes equal to or more than the front wheel air supply time TCSF, it is judged "YES" in step C26, the air supply solenoid valve 20 is turned off, and the air supply operation on the front wheel side is stopped. (Steps C26, C2
7). As a result, the air spring chamber 3 of the front wheel on the air supply side is
Is maintained in a high-pressure state in which air is supplied for the supply time TCSF.

Further, the count value of the timer T is the front wheel exhaust time T
When it becomes CEF or more, it is determined to be "YES" in Step C28, and the exhaust operation on the front wheel side is stopped (Step C2).
9). As a result, the air spring chamber 3 of the front wheel on the exhausted side
Is maintained in a low pressure state where it is exhausted for the front wheel exhaust time TCEF.

Similarly, when the count value of the timer T becomes equal to or more than the rear wheel air supply time TCSR, it is determined "YES" in step C30, the air supply solenoid valve 24 is turned off,
The air supply operation on the rear wheel side is stopped (steps C30 and C3).
1). As a result, the air spring chamber 3 of the rear wheel on the air supply side is
Is maintained in a high-pressure state in which air is supplied for the supply time TCSR.

Further, the count value of the timer T is the rear wheel exhaust time T
When it becomes CER or more, it is determined to be "YES" in step C32, and the exhaust operation on the rear wheel side is stopped (step C3).
3). As a result, the air spring chamber 3 of the rear wheel on the exhausted side
Is kept in a low pressure state where it is exhausted for the rear wheel exhaust time TCER.

Then, it is determined whether the count value of the timer T is equal to or greater than Tmax (step C34a). If "YES" is determined in this step C34a, the direction of the lateral acceleration G is stored in the memory Mg, the control flag is reset, the roll control is stopped, the flow rate switching valve 19 is turned off, That state is held (steps C34b to C35d). In this way, the roll generated on the vehicle body during turning is suppressed. Then, it is determined whether the acceleration flag ACFLG or the braking flag CSFLG is "1" (step C35e), and when the determination is "YES", the acceleration flag ACFLG or the braking flag CSFLG is set to "0" (step S35e). C35f).

The above processing has been described for the case where the steering wheel is steered abruptly. However, even if "ΘH'≤30 deg / sec", if "G × G '" is positive (step C3).
4), referring to the G sensor map in FIG. 9, control level T
The CG is obtained, and the same processing as that in the case of obtaining the TCH is performed and the roll control is performed. In FIG. 9, V1 is 30
km / h and V2 are set to 130 km / h. The supply / exhaust time and the damping force corresponding to this control level TCG can be obtained from FIG. Similarly, the relationship between the left and right G, the vehicle speed V, the control level, the mode, the supply / exhaust time and the damping force shown in FIGS. 9 and 11 is stored in the memory in the control unit 36. As is apparent from FIGS. 9 and 11, the air supply / exhaust time finally obtained from the G sensor map also differs depending on the mode selected by the control switch 30. Although the soft mode is not shown in FIG. 11, this means that when the soft mode is selected, the control level is always zero in the G sensor map.

Incidentally, as will be described later in detail in the description of the supply / exhaust time correction routine C7, in this apparatus, the supply time of the front wheels and the supply / exhaust time of the rear wheels are set to be different from each other. Therefore, the supply / exhaust time is counted independently on the front wheel side and the rear wheel side based on the count of the supply / exhaust time.

By the way, when "G × G '" is negative, that is, when the steering wheel is on the return side, the vehicle speed-steering wheel angular speed map on the return side in FIG. 7 is referred to (step C3).
6) The threshold value ΘHM 'is obtained, and it is determined whether or not the steering wheel angular velocity ΘH' ≥ ΘHM 'on the returning side (step C).
37). If "YES" is determined in the step C37, the temporal change G'of the lateral acceleration G is 0.6 g.
It is determined whether or not / sec or more (step C38). Here, when it is determined to be "YES" in the above steps C37 and C38, that is, when the turning traveling is changed to the straight traveling, the steering wheel is rapidly returned to its neutral position and the temporal change G'of the acceleration G is determined. If it is large, so-called rocking back occurs in which the single body passes the neutral state and rolls to the opposite side, so in order to prevent this, step C
Processing after 39 is performed.

At step C39, it is judged if the swing back flag is set. Here, when the routine firstly returns to step S39, the swing back flag is not set, so that it is determined to be "NO", the swing back flag is set, and the swing back timer TY is set to "0" ( Steps C40, C41). When it is determined that the acceleration G stored in the memory Mg is left (right turn), the front and rear right solenoid valves 23, 27 are provided.
Is turned off, and when it is determined that the acceleration G is right (left turn), the front and rear left solenoid valves 22, 2 are
6 is turned off, and the air spring chambers 3 of the left and right suspension units are communicated with each other (steps C42 to C4).
4). As a result, the timing of communication between the air spring chambers 3 of the left and right suspension units is accelerated, so that the pressure difference between the left and right air spring chambers 3 caused by the roll control is prevented from increasing the rolling back of the vehicle body. To be done. Further, the front and rear air supply valves 20 and 24 are turned off, the exhaust direction switching valves 28 and 32 are turned off, the differential pressure holding flag is reset, the control level CL = 0, and the control flag is also reset. Then, the process returns to step C1 (steps C45 to C49). Then, in steps C37 and C38, it is determined to be "YES",
When the process proceeds to step C39, the rewind flag has already been set, so the process proceeds to the rewind routine after step C50.

That is, the count value of the timer TY is incremented,
It is determined whether the count value of the timer TY is 0.25 seconds or more (steps C50 and C51). If "NO" is determined in the step C51, the above step C1 is performed.
When the timer TY is stepped through the subsequent processes and the count value of the timer TY becomes 0.25 seconds or more, it is again determined whether the count value of the timer TY is 2.25 seconds or more (step C52). Therefore, when the count value of the timer TY is 0.25 seconds or more and less than 2.25, in the step C52,
It is determined to be "NO", and the processing proceeds to step 53 and thereafter.
If it is determined in step C53 that the acceleration G is in the left-right direction and the direction of the memory Mg is right, the front and rear left solenoid valves 22, 26 are determined.
Is turned on, and when it is determined that the lateral acceleration G is left, the front and rear right solenoid valves 23, 2 are
7 is turned on. Further, the exhaust direction switching valve 28,
32 is turned on (steps C53 to C56). By the processing in step C54, the spring constants of the front and rear suspension units can be increased.
In this way, when the steering wheel angular velocity Θ H ′ is equal to or greater than the threshold value in FIG. 7 and the temporal change G ′ of the return-side lateral acceleration G is
When it becomes 0.6 g / sec or more, the left and right air spring chambers 3 are immediately communicated with each other, and the differential pressure between the left and right air spring chambers 3 caused by the roll control increases the rolling back of the vehicle body. Is prevented. Further, 0.25 seconds after that, the left-right communication is closed for 2 seconds, so that when the vehicle body returns to its neutral state, the spring constant of each air spring chamber 3 increases and the rolling of the vehicle body to the opposite side is reduced. And 2.
After 25 seconds, it is determined to be "YES" in step C52, the swing back flag is reset, and the swing back processing is ended. (Step C57). Thereafter, the processing of the step C42 and thereafter is performed, and thereafter, the processing of the step C1 and thereafter is performed.

By the way, the above step C37 or C
When it is determined to be "NO" in 38, that is, when the steering wheel is slowly returned when shifting from turning to straight traveling, or when the temporal change G'of the acceleration G is small,
Since the above-mentioned control relating to swing back is not suitable, the control described below is performed. That is, first, it is determined whether or not the swing back flag is set (step C58), and if it is set, the process proceeds to step C50 and subsequent steps. This may actually be the case in the control process for rollback.

On the other hand, since the swing-back flag is not set when the above-described turning traveling is slowly shifted to straight traveling, it is determined to be "NO" at step C58.
Next, it is determined whether the acceleration G in the left-right direction is in the dead zone level, that is, "G≤G0" (step C5).
9) If it is in the dead zone level, it is judged whether the differential pressure is being held (step C60). If the differential pressure is being held,
Proceeding to the processing of step C61 and thereafter, it moves to the processing of gradually releasing the differential pressure between the left and right air spring chambers 3 by duty control.

The processing of the duty control routine performed after step C61 will be described below. First, it is determined whether the duty control count Tn is 3 or more (step C61). Then, the duty timer Td is set to Tmn
It is determined whether or not the above is true (step C62). Here, since both TD and Tmn are initially "0", "YE
S ”is determined. However, in the same step C62, "NO"
If so, the duty timer Td is incremented (step C63), and the processing for making the damping force of the shock absorber 1 one step harder is performed by steps C64 to 67. Although not shown in the figure, between steps C63 and C64, after the damping force of the shock absorber 1 is set in step C66 or C67 in one control for releasing the differential pressure between the left and right air spring chambers 3 There is provided a step of returning after finishing the process of C63.

By the way, it is judged "YES" in the judgment in step C62, that is, the duty timer Td.
Becomes Tmn, the process proceeds to step C68 and thereafter, and the process of intermittently communicating the left and right air spring chambers 3 is started. First, the direction Mg of the acceleration G in the left-right direction stored in step C31 is determined (step C68).
When the direction of the acceleration G in the left-right direction is the left side,
In step C69, it is determined whether the front and rear right solenoid valves 23, 27 are off. Initially, these valves 23, 27 are on (that is,
Since it is in the differential pressure state), it is turned off in step C71. As a result, the left and right air spring chambers 3 are communicated with each other, and the air in the left air spring chamber 3 flows into the right air spring chamber 3. Further, in steps C72 and C73, the duty counter Tn is incremented and the duty timer Tmn is set to "Tmn +.
"Tm" (Tn is a constant of about 0.1 second) is set, and the process returns to step C1. Then, after Tm seconds, it is determined to be "YES" in step C62 and "left" in C68, and the process reaches C69. At step C69, the right solenoid valves 23 and 27 have already been turned off, so that a "YES" determination is made, and the routine proceeds to step C70, where the solenoid valve 2
3, 27 are turned on. Next, the routine proceeds to step C73, where "Tmn + Tm" is set to the duty timer Tmn. In this way, the solenoid valves 23 and 27 are set to T
If the process of opening for m seconds is performed three times, that is, if the communication between the left and right air spring chambers 3 is performed three times, it is determined to be "YES" in step C61. Then, steps C74 and C
At 75 and C76, the front and rear exhaust direction switching valves 28 and 32 are turned off, the differential pressure holding flag is reset, the control level CL = 0, and the series duty control is ended.

By the way, in the judgment at step C68,
If it is determined to be "right side", steps C69 to C71
The same process as the above is performed for the solenoid valves 22 and 26 on the left side. When this process is also performed three times, the process proceeds to step C74, and the series of processes is ended.

As described above, when the steering wheel is slowly returned during the transition from turning to straight running, or when the temporal change G'of the acceleration G is small, the left and right air springs are controlled by the above series of duty controls. Since the differential pressure between the chambers 3 is gradually eliminated, the inside of each air spring chamber 3 can return to the pre-control state very smoothly.

If it is judged "NO", that is, "G>G0" in the judgment of step C59, it is judged whether the acceleration flag ACFLG = 1 or the braking flag CSFLG = 1 (step C81). ). Then, if "YES" is determined in this step C81, an additional supply / exhaust time is set by the front / rear G supply / exhaust setting routine whose detailed operation will be described later with reference to FIGS. 21 and 22 described later. After that, the process proceeds to step C8 and subsequent steps, and additional roll control is performed. this is,
This is a process for performing additional roll control when acceleration / deceleration is performed during a steady turn.

Next, the supply / exhaust correction routine of step A3 described above will be described in detail with reference to FIGS. First, the internal pressure of the rear suspension units RS1, RS2 is detected by the signal from the pressure sensor 45 (step D2). Next, the control level TCG obtained from the G sensor map of FIG. 9 or the control level TCH obtained from one of the steering wheel angular velocity-vehicle speed maps of FIGS. 6 to 8 is compared with the control level CL (step D3).
D4), when a control level TCG or TCH higher than the control level CL is required, that is the control level CL
(Steps D8 and D17). The control level register CL is set to "0" as an initial value.

On the other hand, if it is judged that either the control level TCG or TCH is smaller than the control level CL, the supply / exhaust flag SEF is reset, the damping force switching position is reset, and the control levels TCG and TCH. The dead zone level "1" is set to (steps D5 to D).
7).

By the way, after the control level TCG is set to the control level CL in the above step D8, "TCH≤
When it is 1 "(that is, when the lateral acceleration acting on the vehicle body is small), the air supply coefficient Ks is set to" 3 "(step D10). On the other hand, when “TCH> 1” (that is, when the lateral acceleration acting on the vehicle body is small), the air supply coefficient Ks is set to “1” (step D11). When the control level TCH is set to the control level DL in step D17, the air supply coefficient Ks is set to "1" (step D11).

Then, the above step D10 or D1
The supply / exhaust flag SEF indicating that the supply / exhaust control needs to be performed after 1 is set (step D12), and FIG.
Through the roll control routine of FIG. 17, air supply / exhaust is performed. Then, the rough road determination routine (step A in FIG. 12)
It is determined whether the rough road determination set in 1) is set (step D13). In this step D13, when it is determined that the rough road determination is set, it is determined whether the control level TCG is "2" (step D14), and when the control level is "2", the feed is determined. The exhaust flag SEF is reset and the dead band level "1" is set to the control level TCG (steps D15, D1).
6).

That is, as shown in FIG. 11, when the control level TCG is "2" at the time of the rough road determination, it is 15 at the normal time.
The roll control is performed during the supply / exhaust time of 0 ms, but the roll control is not performed because the supply / exhaust time is "0". In other words, when a rough road is determined, such as when driving on a rough road, the dead zone width of the G sensor is widened to prevent the roll control from malfunctioning on a rough road.

By the way, the above steps D7, D13, D
After the processing of 14 and D16 is finished, the basic time Tc of supply and exhaust according to the control levels TCH and TCG is obtained from the obtained control level TCH or TCG with reference to FIG. 10 or FIG. 11 (step D18). . Next, the pressure sensor 45 causes the rear suspension unit RS.
The internal pressures of 1 and RS2 (rear internal pressure) are detected, and the front internal pressure is estimated from this rear internal pressure by referring to a front internal pressure-rear internal pressure characteristic diagram (not shown). From the front internal pressure estimated in this way and the rear internal pressure obtained from the pressure sensor 45, reference is made to the supply air exhaust correction coefficient characteristic diagram (not shown), and the front side and rear side supply air correction coefficients PS,
The air supply correction coefficient PE on the front side and the rear side is obtained (step D19). In this air supply / exhaust correction coefficient characteristic diagram (not shown), when the internal pressure of the suspension is high, the air supply time is longer than that when the internal pressure is low. Coefficient P
S is proportional to the internal pressure P0, and when the internal pressure of the suspension is high, the exhaust time is shorter than the time when the internal pressure is low to exhaust the same amount of air, so the correction coefficient PE is the internal pressure. It is inversely proportional to Po.

Next, it is judged whether or not the compressor 16 (return pump) is stopped (step D20), and when it is stopped, that is, when the pressure difference between the high pressure reserve tank 15a and the low pressure reserve tank 15b is large. ,
Since the air flow rate of the suspension air supply / exhaust is large even for a short time, the initial coefficient FK is set to 0.8 (step D2
1). On the other hand, when it is not stopped, that is, when the pressure difference between the high-pressure reserve tank 15a and the low-pressure reserve tank 15b is small, the initial coefficient FK is set to 1 and the supply / exhaust time is not corrected (step D22).

Next, the basic time Tc of the air supply which has already been obtained is multiplied by the air supply correction coefficient PS, the air supply coefficient KS and the initial coefficient FK to obtain the corrected air supply time TCS (step D23). ). Further, the exhaust correction coefficient PE and the initial coefficient FK are added to the already obtained basic time Tc of the exhaust gas.
Is multiplied to obtain the corrected exhaust time TCE (step D24). The air supply time TCS and the exhaust time TCE are calculated individually because they have different correction coefficients on the front wheel side and the rear wheel side, respectively.

Then, the road surface gradient value RK output from the A / T control ECU 56 to the control unit 36 is read (step D25). Then, it is determined whether the road surface gradient value RK is ± 2% or more (step D26).

If the determination in step D26 is "NO", the gradient correction flag KTAFLG is set to "0" (step D27), and if the determination is "YES", the gradient correction flag KTAFLG is set. "1" is set (step D28). Then, referring to the map of FIG. 25, the front wheel supply / exhaust gas distribution coefficient KTAF and the rear wheel supply / exhaust gas distribution coefficient KTAR that are exhibited in the road surface gradient RK are obtained (step D).
29). That is, as shown in FIG. 25, the rear wheel supply / exhaust gas distribution coefficient KTAR is "1" up to a certain value of the road surface gradient RK, and up to 1.5 in proportion to the road gradient RK in proportion to the certain value or more. It rises and is "1" until the road slope reaches a certain value, and the slope RK when the road is below the certain value.
It decreases to 0.5 in proportion to.

Further, the front wheel supply / exhaust air distribution coefficient KTAF is "1" until the road surface gradient RK reaches a certain value, and when the road surface gradient RK is more than the certain value, it decreases to 0.5 in inverse proportion to the road gradient. The value is "1" up to a certain value, and rises to 1.5 in inverse proportion to the gradient RK when the gradient is less than the certain value. That is, as the degree of descending slope increases, the distribution on the rear wheel side in the front-rear distribution of roll control decreases. This is because the vehicle is controlled to understeer by reducing the rear wheel side distribution of roll control.

Further, as the degree of climbing increases, the distribution on the rear wheel side with respect to the front / rear distribution of roll control increases. This is because the vehicle is controlled to oversteer by increasing the rear wheel side distribution of roll control. Next, acceleration flag ASFLG = 1 or braking flag CS
It is determined whether FLG = 1 (step D30).

If "YES" is determined in this step D30, the front wheel supply / exhaust gas distribution coefficient KXGF and the rear wheel supply / exhaust gas distribution coefficient KXGR are determined by referring to the map of FIG. 31 (step D31), When it is determined to be "NO", "1" is set to each of the front wheel supply / exhaust gas distribution coefficient KXGF and the rear wheel supply / exhaust gas distribution coefficient KXGR. That is, FIG.
As shown in, the rear wheel supply / exhaust gas distribution coefficient KXGR is "1" until the front and rear G have a certain value, and the front and rear G is equal to or more than the certain value.
Then, it rises to 1.5 in proportion to the front-rear G, and is "1" until the road surface gradient reaches a certain value, and falls to 0.5 in front-rear G below the certain value in proportion to the front-rear G. .

Further, the front wheel supply / exhaust gas distribution coefficient KXGF is the front / rear G
Is 1 up to a certain value, and before and after G above the certain value decreases to 0.5 in inverse proportion to the front and rear G, and before and after G up to a certain value, it is 1 In the front and rear G below the value, it rises to 1.5 in inverse proportion to the front and rear G. That is, as the acceleration increases, the distribution on the rear wheel side is increased with respect to the distribution before and after the roll control. This is because the vehicle is controlled to oversteer by increasing the rear wheel side distribution of roll control. On the other hand, as the degree of deceleration increases, the front-rear distribution of roll control is reduced on the rear wheel side. This is because the vehicle is controlled to understeer by reducing the rear wheel side distribution of roll control.

After the processing of step D31 or D32 described above is completed, the air supply time TCS calculated in step D23 described above is multiplied by the front wheel supply / exhaust gas distribution coefficients KTAF and KXGF to calculate the front wheel air supply time TCSF, and step D24.
Exhaust time TCE calculated in
And KXGF are multiplied to calculate the front wheel exhaust time TCEF. Further, the air supply time TCS calculated in step D23 is multiplied by the rear wheel supply / exhaust gas distribution coefficients KTAR and KXGR to calculate the rear wheel air supply time TCSR, and step D24.
Exhaust time TCE calculated in
And KXGR are multiplied to calculate the rear wheel exhaust time TCER (step D33). And these times TCSF, T
The maximum supply / exhaust time Tmax is calculated from CEF, TCSR, and TCER (step D34).

Next, referring to FIGS. 10 and 11, the damping force switching position corresponding to the control levels TCG, TCH is obtained,
The position is set to the damping force target value DST (step D35). Next, when the rough road determination is set, if the damping force target value DST is hard, it is changed to medium (steps D36 to D38). This improves the ability of the wheels to follow the road surface when traveling on a rough road.

Next, referring to FIGS. 21 and 22, FIG.
The operation of the air supply / exhaust setting routine by the front and rear G performed in step C82 will be described. First, the air supply / exhaust flag S
It is determined whether "1.0" is set in EF (step E1). If "NO" is determined in this step E1, the front-rear G detected by the acceleration sensor 39b is applied to the map of FIG.
XGF and rear wheel supply / exhaust air distribution coefficient KXGR are calculated, and front wheel air supply time TCSF, rear wheel air supply time TCSR, front wheel exhaust time TCEF,
The rear wheel exhaust time TCER is calculated by the following equation (step E2). TCSF = (KXGF -1.0) * TCSF TCSR = (KXGR -1.0) * TCSR TCEF = (KXGF -1.0) * TCEF TCER = (KXGR -1.0) * TCER

For example, when braking and turning while maintaining the differential pressure of the roll control, the front wheel supply / exhaust air distribution coefficient KXGF becomes larger than 1, so both the front wheel air supply time TCSF and the front wheel exhaust time TCEF are values of ">0". Becomes On the other hand, since the rear-wheel supply / exhaust distribution coefficient KXGR is smaller than 1, both the rear-wheel supply time TCSR and the rear-wheel exhaust time TCER are "<0".

In the following, when the front wheel air supply time TCSF, the rear wheel air supply time TCSR, the front wheel exhaust time TCEF, and the rear wheel exhaust time TCER are “≦ 0” by the processing of steps E3 to E10, the front wheel air supply is performed. "0" is set to the time TCSF, the rear wheel air supply time TCSR, the front wheel exhaust time TCEF, and the rear wheel exhaust time TCER. That is, as a result of the calculation in step E2, the front wheel air supply time TCSF, the rear wheel air supply time TCSR, the front wheel exhaust time TCEF
When the rear wheel exhaust time TCER is “≦ 0”, the supply / discharge control is not performed.

Therefore, in the case where the vehicle makes a braking turn while maintaining the differential pressure of the roll control as described above, the front wheel air supply time T
Since only CSF and front wheel exhaust time TCEF are ">0", additional control of the roll control on the front wheel side is performed. As a result, the steering of the vehicle tends to be understeer to prevent oversteering even when the vehicle makes a braking turn while maintaining the differential pressure of the roll control.

Next, the front wheel air supply time TCSF, the rear wheel air supply time TCSR, the front wheel exhaust time TCEF calculated in step E2,
The maximum supply / exhaust time Tmax is obtained from the rear wheel exhaust time TCER, the supply / exhaust flag SEF is set to "1.0", and the process returns to step C8 and subsequent steps of the roll control routine. Hereinafter, the process of the step when the roll control is first performed is executed, and the additional roll control is performed (in this case, only the front wheel side). By the way, when it is determined to be "YES" in step E1, the processes of steps E2 to E12 are skipped.

Next, the rear steering angle calculation method performed by the 4WS ECU 55 will be described with reference to the flowcharts of FIGS. The 4WS ECU 55 reads the steering wheel angle θH detected by the steering wheel angle sensor (not shown) and the steering wheel angular velocity θH ′ detected by the steering sensor 40 (step F1), and reads the vehicle speed V detected by the vehicle speed sensor 38 (step F2). The throttle opening THV detected by the throttle opening sensor 42 is read (step F3), and the detection signal of the brake switch 46 is read (step F4). Then, the in-phase coefficient K1 corresponding to the vehicle speed V is obtained by referring to the map of FIG. 26 (step F5). Next, referring to the map of FIG. 27, the instantaneous anti-phase coefficient K2 for the vehicle speed V is obtained (step F6).

Then, the already read vehicle speed V and throttle opening THV are applied to the map of FIG. 28 to determine whether the vehicle is in the acceleration condition (step F7). And
When it is determined in step F7 that the acceleration condition is satisfied, the lateral G is calculated by a known calculation formula, and the momentary reverse phase magnification KG2 for the calculated lateral G is obtained from the map of FIG. 29 (step F8). Then, the acceleration flag ACFLG is set to "1" (step F9). On the other hand, if the determination in step F7 is "NO", the acceleration flag
ACFLG is set to "0" (step F10).

Next, it is judged from the detection signal of the brake switch 46 whether the brake switch 46 is turned on, that is, whether the brake pedal is depressed to apply the braking (step F11). If the determination in step F11 is "Y
If "ES" is determined, the lateral G is calculated by a known calculation formula.
Is calculated, the characteristic map corresponding to the calculated lateral G is selected, and the front and rear G detected by the acceleration sensor 39b is applied to the selected map to obtain the rear wheel steering angle distribution Δδr (step F12). Then, the braking flag CSFLG is set to "1" (step F13). On the other hand, if the determination in step F11 is "NO", the braking flag CSFLG is set to "0". Next, the rear steering angle value δr is calculated by the following equation. δr = (K1 θH + K2 KG2 θH ′) / ρ + Δδr where ρ is the overall steering gear ratio.
Then, the 4WS ECU 55 outputs a drive signal to the solenoids a and b of the electromagnetic switching valve 71 to steer the rear wheels so that the rear wheel steering angle value δr is obtained.

As described above, when the vehicle is in the braking and turning state, the steering characteristics of the vehicle are made understeer by increasing the front wheels in the distribution during the roll control, and the in-phase steering amount of the rear wheels is the same. By slightly increasing the steering amount, the center-of-gravity slip angle can be reduced, and the braking turn can be smoothly performed.

That is, as shown in FIG. 3A, when ECS + 4WS control is not performed as indicated by the present invention (one-dot chain line), the vehicle turns while decelerating [front and rear G descends as shown in FIG. 32 (B)]. If you turn the steering wheel, the steering will be over steered, so you have to repeat the operation to return the steering wheel. Therefore, the yaw angular velocity will increase or decrease.
Since the steering is controlled in the understeer direction by combining with WS, the steering operation can be smoothly performed as indicated by the solid line.

That is, as shown in FIG. 32 (C), ECS
Without + 4WS control (dashed-dotted line), when turning while accelerating [front and rear G rises as shown in FIG. 32 (D)], understeer occurs and the yaw angular velocity falls as shown by A, but ECS and 4WS By controlling in combination with and, understeering is suppressed as shown by the solid line, and the turning performance is improved.

When the vehicle is in the decelerating turning state, the steering characteristic of the vehicle is made understeer by reducing the rear wheels in the distribution during the roll control, and the in-phase steering amount is related to the rear wheel steering amount of the four-wheel steering. Is slightly increased to reduce the center-of-gravity slip angle, reduce excessive headout, and make the vehicle easier to bend. In the above embodiment, the roll control is performed by using the pneumatic suspension, but the hydraulic suspension may be similarly used.

[0082]

As described above in detail, according to the present invention, there is provided an electronically controlled suspension device capable of smoothly performing a turn by reducing the tendency of the vehicle to oversteer when the vehicle makes a turn while braking. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing an electronically controlled suspension control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a four-wheel steering system according to the embodiment.

FIG. 3 is a diagram showing a driven / non-driven state of a three-way valve.

FIG. 4 is a diagram showing a driven state and a non-driven state of a solenoid valve.

FIG. 5 is a diagram showing a drive state and a non-drive state of a supply air flow rate control valve.

FIG. 6 is a vehicle speed-steering wheel angular velocity map in SOFT mode.

FIG. 7 is a vehicle speed-steering wheel angular velocity map in AUTO mode.

FIG. 8 is a vehicle speed-steering wheel angular velocity map in SPORT mode.

FIG. 9 is a G sensor map.

FIG. 10 is a diagram showing a relationship between a control level and a supply / exhaust time based on a vehicle speed-steering wheel angular velocity map.

FIG. 11 is a diagram showing a relationship between a control level and a supply / exhaust time based on a G sensor map.

FIG. 12 is a schematic flowchart showing the operation of one embodiment of the present invention.

FIG. 13 is a part of a detailed flowchart of a roll control routine.

FIG. 14 is a part of a detailed flowchart of a roll control routine.

FIG. 15 is a part of a detailed flowchart of a roll control routine.

FIG. 16 is a part of a detailed flowchart of a roll control routine.

FIG. 17 is a part of a detailed flowchart of a roll control routine.

FIG. 18 is a part of a flowchart showing a supply / exhaust correction routine.

FIG. 19 is a part of a flowchart showing a supply / exhaust correction routine.

FIG. 20 is a part of a flowchart showing a supply / exhaust correction routine.

FIG. 21 is a part of a flowchart showing a supply / exhaust setting routine.

FIG. 22 is a part of a flowchart showing a supply / exhaust setting routine.

FIG. 23 is a part of a flowchart showing a rear steering angle determination routine.

FIG. 24 is a part of a flowchart showing a rear steering angle determination routine.

FIG. 25 is a diagram showing road surface slope characteristics of a front wheel supply / exhaust gas distribution coefficient KTAF and a rear wheel supply / exhaust gas distribution coefficient KTAR.

FIG. 26 is a diagram showing a vehicle speed characteristic of an in-phase coefficient K1.

FIG. 27 is a diagram showing a vehicle speed characteristic of an instantaneous antiphase coefficient K2.

FIG. 28 is a diagram showing an “acceleration” determination map according to vehicle speed V-throttle opening THV.

FIG. 29 is a diagram showing an instantaneous antiphase magnification coefficient KG2-calculated lateral G characteristic map.

FIG. 30 is a diagram showing a rear wheel steering angle distribution Δδr-front and rear G characteristic map.

FIG. 31 is a diagram showing front and rear G characteristic maps of front wheel supply / exhaust gas distribution coefficient KXGF and rear wheel supply / exhaust gas distribution coefficient KXGR.

FIG. 32 is a diagram showing yaw angular velocity and longitudinal G characteristics during acceleration and deceleration turning.

[Explanation of symbols]

15a ... High-pressure reserve tank, 15b ... Low-pressure reserve tank, 19 ... Supply air flow control valve, 22, 23, 26,
27 ... Solenoid valve, 36 ... Control unit, 36 ... Control unit, 55 ... EC for 4WS
U, 56 ... A / T control ECU.

Claims (1)

[Claims] 1. A roll detecting means for detecting a factor causing a roll on a vehicle body, a suspension unit in which a fluid chamber is provided for each wheel so that a supporting force for the vehicle body can be independently adjusted, and a roll for the vehicle body. In an electronically controlled suspension control device having control means for changing the supporting force of the left and right suspension units by a roll control amount according to the detection output of the roll detection means so as to suppress the braking for detecting the braking state of the vehicle. State detection means, and when the braking state of the vehicle is detected by this braking state detection means, roll control amount distribution for correcting the roll control amount on the front wheel side to be larger than the roll control amount on the rear wheel side. When the braking of the vehicle is detected by the correction means, the rear wheel steering means for steering the rear wheels, and the braking state detection means, the rear wheel steering is performed. Electronic controlled suspension apparatus characterized by comprising a rear wheel steering control means after controlling to increase the phase steering angle of the rear wheels by stage.