JP3324345B2 - Vehicle behavior control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control turning action of a vehicle by accurately controlling braking force by providing a suspension characteristics control means for setting a suspension characteristic to a hard characteristic when the braking force is controlled by means of an action controller for stabilizing the turning action. SOLUTION: An output/input port device of a micro-computer 52 is so constituted as making input/output of a signal to/from a suspension controlling electric controller 72 for controlling damping force of a shock absorber of a suspension 70. And, when turning action of a vehicle comes in its unstable state, the micro- computer 52 has the damping force of the shock absorber of the suspension 70 set in hard state. Thus, it is possible that any variation of a supported load on each wheel caused by load movement is reduced and inertia of a driving system is reduced automatically and influence of external turbulent torque given to driving wheels from the driving system can be certainly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a behavior control device for suppressing and reducing undesirable behaviors such as drift-out and spin during turning of a vehicle such as an automobile.

[0002]

2. Description of the Related Art As one of devices for controlling the behavior of a vehicle such as an automobile at the time of turning, for example, Japanese Patent Application Laid-Open No.
As described in Japanese Patent Application Laid-Open No. 559, the braking force of the vehicle is increased at the time of the so-called vehicle turning limit at which the lateral force of the wheel becomes a limit state.
2. Description of the Related Art There has been conventionally known an apparatus for reducing a vehicle speed by stabilizing a turning behavior by reducing a driving force of an engine.

[0003]

Generally, in order to reduce the vehicle speed and stabilize the turning behavior by controlling the braking force at the time of the turning limit of the vehicle, it is necessary to accurately control the braking force actually generated by the wheels on the road surface. You need to control. However, even if the target slip ratio of the wheels is determined according to the turning state of the vehicle and the braking pressure is controlled so that the slip ratio of the wheels becomes equal to the target slip ratio, the braking force actually generated is a disturbance applied to the wheels, for example, a wheel. Therefore, the turning behavior is not necessarily controlled with high accuracy due to the fluctuation of the supporting load and the disturbance torque from the drive system.

The present invention has been made in view of the above-mentioned problems in the conventional behavior control device, and a main object of the present invention is to control the braking force of the wheels at the time of the turning limit of the vehicle to turn the vehicle. When stabilizing the behavior, the influence of the disturbance applied to the wheels is reduced as much as possible, so that the braking force of the wheels is accurately controlled and the turning behavior of the vehicle is accurately controlled.

[0005]

Means for Solving the Problems] major challenges such as described above, according to the present invention, means for detecting a turning limit of the vehicle, vehicle turning behavior when the turning limit of the vehicle is detected
Calculate the target slip ratio of each wheel according to the
Control means for stabilizing the turning behavior by controlling the braking force of each wheel so that the slip rate becomes the target slip rate; and suspension characteristics when the braking force of the wheels is controlled by the behavior control means. means for detecting a behavior control device (the first aspect), or turning limit of the vehicle of the vehicle and a suspension characteristic control means for setting to a hard characteristic, the car when the turning limit of the vehicle is detected
Calculate the target slip ratio of each wheel according to the turning behavior of the vehicle,
Each wheel is adjusted so that the slip rate of each wheel becomes the target slip rate.
A vehicle having a behavior control means for stabilizing the turning behavior by controlling the braking force of the vehicle and an inertia reducing means for reducing the inertia of the drive system when the braking force of the wheels is controlled by the behavior control means. This is achieved by the control device (the configuration of claim 2).

As is well known, when the vehicle turns, the supporting load of each wheel fluctuates due to the movement of the load. However, the suspension characteristic is a hard characteristic, and the relative displacement between the sprung and unsprung is hard to occur. Fluctuation in the support load of each wheel due to the load movement is reduced.

[0007] According to the above-mentioned arrangement of claim 1, the turning limit of the vehicle is discovered, of each wheel in accordance with the turning behavior of the vehicle
The target slip ratio is calculated, and the slip ratio of each wheel is set to the target slip ratio.
By controlling the braking force of each wheel to achieve the lip rate
When the turning behavior of the vehicle is stabilized, and when the braking force of the wheels is controlled by the behavior control means, the suspension characteristics are set to the hard characteristics by the suspension characteristic control means, and the suspension characteristics are set to the hard characteristics by the load movement. Since the fluctuation of the supporting load is reduced, the braking force of the wheels is controlled with higher accuracy than in the case where the suspension characteristics are soft characteristics, whereby the turning behavior is accurately controlled.

When the wheel is a driving wheel, the driving torque from the driving system acts on the wheel as a disturbance, and the braking effect of the wheel fluctuates due to the disturbance. The smaller the inertia, the smaller.

[0009] According to the second aspect described above, the turning limit of the vehicle is discovered, each in accordance with the turning behavior of the vehicle
The target slip ratio of each wheel is calculated, and the slip ratio of each wheel is estimated.
The braking force of each wheel is controlled to achieve the target slip ratio
When the turning behavior of the vehicle is stabilized by the vehicle and the braking force of the wheels is controlled by the behavior control means,
Since the inertia of the drive system is reduced by the inertia reduction means, the influence of the disturbance torque applied to the drive wheels from the drive system is reduced, whereby the braking force of the drive wheels is controlled with high accuracy, so that the turning behavior of the vehicle is reduced. It is controlled precisely.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of claim 2, the inertia reducing means detects the spin state as a turning limit of the vehicle and controls the behavior. When the braking force of the wheels is controlled by the means, the shift stage of the automatic transmission is switched to the neutral or high speed stage to reduce the inertia of the drive system (the configuration of claim 3).

[0011] Car This According to the third aspect, the spin condition is detected as a turning limit of the vehicle behavior control means
When the braking force of the wheels is controlled, the inertia of the drive system is reduced by switching the shift speed of the automatic transmission to the neutral or the high speed by the inertia reduction means.
The influence of the disturbance torque applied to the drive wheels from the drive system is reliably reduced.

According to the present invention, in order to effectively attain the above-mentioned main object, in the configuration of claim 2, the inertia reducing means detects a drift-out state as a turning limit of the vehicle and detects the behavior. When the braking force of the wheels is controlled by the control means, the inertia of the drive system is reduced by switching from the 4WD state to the 2WD state.

According to this configuration, when the drift-out state is detected as the turning limit of the vehicle and the braking force of the wheels is controlled by the behavior control means, the inertia reduction means switches from the 4WD state to the 2WD state. This reduces the inertia of the drive train,
The influence of the disturbance torque applied to the drive wheels is reliably reduced, and the switching from the 4WD state to the 2WD state changes the steer characteristic in the oversteer direction, thereby effectively reducing the drift-out state of the vehicle.

[0014]

According to a preferred embodiment of the present invention, the means for detecting the turning limit of the vehicle according to the first or the second aspect of the present invention is based on a physical quantity representing the skid of the vehicle. It is determined whether or not the behavior of the vehicle is in a spin state, and it is determined whether or not the behavior of the vehicle is in a drift-out state based on a physical quantity representing the yaw rate of the vehicle,
When the behavior of the vehicle is in a spin state or a drift-out state, the vehicle is determined to be at the turning limit.

According to another preferred aspect of the present invention, the suspension characteristic is the damping force of the shock absorber or the spring constant of the suspension spring. Is configured to set the suspension characteristics to hard characteristics by setting the damping force of the shock absorber to a high damping force or setting the spring constant of the suspension spring to a high spring constant.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIGS. 1 and 2 are a schematic configuration diagram showing a braking device of one embodiment of a behavior control device according to the present invention and a block diagram showing an electric control device, respectively.

In FIG. 1, a braking device 10 has a master cylinder 14 for pumping brake oil from first and second ports in response to a driver's depressing operation of a brake pedal 12, and a first port. Is connected to brake hydraulic control devices 18 and 20 for the front left and right wheels by a brake hydraulic control conduit 16 for the front wheels, and the second port is connected to the rear left and right wheels by a brake hydraulic control conduit 24 for the rear wheels having a proportional valve 22 in the middle. Brake hydraulic control devices 26 and 28. Further, the braking device 10 pumps up the brake oil stored in the reservoir 30 and supplies it to the high-pressure conduit 32 as high-pressure oil.
Four. The high-pressure conduit 32 is connected to each of the brake hydraulic control devices 18, 20, 26, 28, and an accumulator 36 is connected in the middle thereof.

Each of the brake hydraulic control devices 18, 20, 2
6, 28 are wheel cylinders 38FL, 38FR, 38RL, 38RR for controlling the braking force on the corresponding wheels, respectively.
And a 3-port 2-position switching type electromagnetic control valve 40FL,
The normally open electromagnetic on-off valves 44FL, 44FR, 44RL, 44RR provided between the 40FR, 40RL, 40RR and the low pressure conduit 42 and the high pressure conduit 32 connected to the reservoir 30 and the normally closed electromagnetic valve On-off valves 46FL, 46FR, 46RL, 46
RR. On-off valves 44FL, 44FR, 4 respectively
4RL, 44RR and open / close valve 46FL, 46FR, 46RL, 46RR
High-pressure conduit 32 between the connection conduits 48FL, 48FR, 48
Control valve 40FL, 40FR, 40RL, 40 by RL, 48RR
Connected to RR.

The control valves 40FL and 40FR are respectively a brake hydraulic control conduit 16 for the front wheels and a wheel cylinder 38FL.
And 38FR and wheel cylinder 38FL
, 38FR and the connection conduits 48FL and 48FR, the first position shown in the figure, the brake hydraulic control conduit 16 and the wheel cylinders 38FL and 38FR, and the wheel cylinders 38FL and 38FR and the connection conduit 48FL.
, And a second position for communicating and connecting with the 48FR. Similarly, 40RL and 40RR are respectively a brake hydraulic control conduit 24 for the rear wheel and a wheel cylinder 3
8RL and 38RR, and wheel cylinder 3
8RL and 38RR and the first position shown to cut off the communication between the connecting conduits 48RL and 48RR, and the brake hydraulic control conduit 2
4 to cut off the communication between the wheel cylinders 38RL and 38RR and connect the wheel cylinders 38RL and 38RR to the connecting conduit 4.
The position is switched to a second position for communicating and connecting 8RL and 48RR.

When the control valves 40FL, 40FR, 40RL, 40RR are in the second position, the on-off valves 44FL, 44FR,
44RL, 44RR and on-off valves 46FL, 46FR, 46RL, 4
When 6RR is controlled to the state shown in FIG.
8FL, 38FR, 38RL, 38RR are control valves 40FL, 40F
R, 40RL, 40RR and connecting conduit 48FL, 48FR, 48R
L and 48RR are connected to the high-pressure conduit 32 to increase the pressure in the wheel cylinder. Conversely, when the control valve is in the second position, the on-off valve 44FL,
4FR, 44RL, 44RR are closed and on-off valves 46FL, 46F
When R, 46RL, 46RR is opened, the wheel cylinder is connected in communication with the low pressure conduit 42 via the control valve and the connecting conduit, thereby reducing the pressure in the wheel cylinder. Further, when the control valve is in the second position, the on-off valves 44FL, 44FR, 44RL, 44RR and the on-off valves 46FL,
When the valves 6FR, 46RL, and 46RR are closed, the wheel cylinder is disconnected from both the high-pressure conduit 32 and the low-pressure conduit 42, so that the pressure in the wheel cylinder is maintained.

Thus, the braking device 10 includes a control valve 40FL,
When the 40FR, 40RL, 40RR is in the first position, the wheel cylinders 38FL, 38FR, 38RL, 38RR generate a braking force according to the amount of depression of the brake pedal 12 by the driver, and the control valves 40FL, 40FR, 40RL, 40RR.
When any of RR is in the second position, the on-off valves 44FL, 44FR, 44RL, 44RR and on-off valves 46FL,
By controlling the opening and closing of the wheels 46FR, 46RL and 46RR, the braking force of the wheel can be controlled irrespective of the amount of depression of the brake pedal 12 and the braking force of the other wheels.

Control valves 40FL, 40FR, 40RL, 40RR,
On-off valves 44FL, 44FR, 44RL, 44RR and on-off valves 46
FL, 46FR, 46RL, and 46RR are controlled by the electric control device 50 based on signals from the braking force control electric control device 70, as will be described in detail later. Electric control device 5
0 includes a microcomputer 52, which is not shown in detail in FIG. 2, for example, a central processing unit (CPU) and a read only memory (R).
OM), a random access memory (RAM), and an input / output port device, which may be of a general configuration connected to each other by a bidirectional common bus.

A signal indicating the vehicle speed V from the vehicle speed sensor 56, a signal indicating the lateral acceleration Gy of the vehicle body from a lateral acceleration sensor 58 provided substantially at the center of gravity of the vehicle body, a yaw rate sensor 60 A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θ from the steering angle sensor 62, the wheel speed sensors 64FL, 64FR, 6
Wheel speed VFL, VFR, V of the corresponding wheel from 4RL, 64RR
Signals indicating RL and VRR are input. The lateral acceleration sensor 58 and the like detect lateral acceleration and the like with the left turning direction of the vehicle as positive.

The input / output port device of the microcomputer 52 controls the braking device 10 to control the braking force of each wheel. The braking force control amount electric control device 68, and the damping force of the shock absorber of the suspension 70 is used for suspension control. Electric control device 72, center differential device (abbreviated as “center differential” in this specification) 7
Signals are input and output between an electric control device 76 for center differential control for controlling the connection state of the automatic transmission 4 and an electric control device 80 for automatic transmission control for controlling the speed of the automatic transmission 78. I have.

In particular, the ROM of the microcomputer 52 stores the control flow of FIG. 3 and the maps corresponding to the graphs shown in FIGS. 8 and 9 as will be described later. Based on the parameters, various calculations are performed as described later to calculate the final target slip ratio of each wheel, and a control signal is output to the braking force control electric control device 70 and the like.

The electric control devices 68, 72, 76, and 80 each include a microcomputer similarly to the electric control device 50, and perform corresponding control according to control routines shown in FIGS. 4 to 7, respectively. . Although not shown in the figure, when the turning behavior of the vehicle is unstable, that is, when a later-described flag Fs or Fd is 0, the electric control device 50 responds to the spin value SV or the drift value DV. The opening degree of the sub-throttle valve is reduced, thereby reducing the output of the engine.

Next, the outline of the turning behavior control of the vehicle according to the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 3 is started by closing an ignition switch (not shown), and is repeatedly executed at predetermined intervals.

First, in step 10, the vehicle speed sensor 5
6, a signal indicating the vehicle speed V detected is read, and in step 20, the deviation Gy of the lateral acceleration Gy and the product V * γ of the vehicle speed V and the yaw rate γ is calculated as Gy−V * γ. That is, the vehicle slip acceleration Vyd is calculated, and the deviation Vyd of the lateral acceleration is integrated to calculate the vehicle slip speed Vy. The slip angle β of the vehicle body is calculated as the ratio Vy / Vx, and the slip angular velocity βd of the vehicle body is calculated as a differential value of the slip angle β of the vehicle body.

In step 30, the spin value SV is calculated as the absolute value of the linear sum a * β + b * βd of the slip angle β and the slip angular velocity βd, where a and b are positive constants, respectively. Then, based on the spin value SV, the target slip ratio Rsfo of the front wheel outside the turning is calculated from a map corresponding to the graph shown in FIG.

In step 50, the target slip ratio R
It is determined whether or not sfo is 0, that is, whether or not control for spin is unnecessary. If a negative determination is made, the flag Fs is set to 1 in step 60, and an affirmative determination is made. Is performed, the flag Fs is set to 0 in step 70.

In step 80, Kh is a stability factor, L is a wheelbase, and
, And the target yaw rate γt is calculated according to the following equation 2 using T as a time constant and s as a Laplace operator.

[0033]

Γ c = V * θ / (1 + Kh * V ² ) * L

Γt = γc / (1 + T * s)

In step 90, the yaw rate deviation Δ
γ, that is, the deviation of the absolute value of the target yaw rate γt and the absolute value of the actual yaw rate γ of the vehicle is calculated as the drift value DV. In step 100, the drift value DV is calculated based on the absolute value of the drift value DV. A target slip ratio Rdall of the entire vehicle is calculated from a map corresponding to the graph shown in FIG.

In step 110, it is determined whether or not the target slip ratio Rdall of the entire vehicle is 0, that is, whether or not control for drift-out is unnecessary, and a negative determination is made. In some cases, the flag Fd is set to 1 in step 120, and when an affirmative determination is made, the flag Fd is set to 0 in step 130.

In step 140, K1 (0 ≦ K1
≤ 1) is the distribution coefficient of the front wheels, K2 (0 ≤ K2 ≤ 1) is the distribution coefficient of the outer wheels for the front wheels, and K3 (0 ≤ K3 ≤
Assuming that 1) is the distribution coefficient of the outer wheels with respect to the rear wheels, the target slip ratio Rdall of the entire vehicle is determined by the following equation 3 according to the following equation (3): the outer front wheel (fo), the inner front wheel (fi), the outer rear wheel (ro),
It is distributed to the turning inner rear wheel (ri).

## EQU3 ## Rdfo = Rdall * K1 * K2 Rdfi = Rdall * K1 * (1-K2) Rdro = Rdall * (1-K1) * K3 Rdri = Rdall * (1-K1) * (1-K3)

In step 150, K4 (-1≤K
4 ≦ 0) as the rear wheel distribution coefficient, and the target slip ratio Rsf
Based on o, the target slip ratios Rsro and Rsri of the turning outer rear wheel and the turning inner rear wheel are calculated according to the following equation (4).

Rsro = Rsfo * K4 Rsro = Rsfo * K4

In step 160, the final target slip ratios Rfo, Rfi, Rro, and Rri of the front outside wheel, the front inside wheel, the rear outside wheel, and the rear inside wheel are calculated according to the following equation (5).
Is set as follows.

Rfo = Rdfo Rfi = Rdfi Rro = Rdro + Rsro Rri = Rdri + Rsri

Next, the outline of the braking force control according to the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 4 is also started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

In step 200, signals such as the target slip rates Rfo, Rfi, Rro, and Rri are read. In step 210, the target slip rates Rfo, Rfi, and Rfi are read.
It is determined whether or not all of ro and Rri are 0, and when a positive determination is made, that is, when the target slip ratios Rfo and Rfo are determined.
If fi, Rro, and Rri are all 0, step 10
When the negative determination is made, that is, when at least one of the target slip rates Rfo, Rfi, Rro, and Rri is not 0, in step 220, the wheel speed of the front wheel inside the turning is set to the reference wheel speed Vb. .

In step 230, the reference wheel speed Vb
The target wheel speed Vwtfo of each wheel according to the following Equation 6 based on
Vwtfi, Vwtro, and Vwtri are calculated.

Vwtfo = Vb * (1-Rfo) Vwtfi = Vb * (1-Rfi) Vwtro = Vb * (1-Rro) Vwtri = Vb * (1-Rri)

In step 240, the braking force of each wheel is controlled so that the wheel speed of each wheel becomes the target wheel speed. That is, first, the duty ratios Drfo, Drfi, Drro, and Drri are calculated according to the following equation (7). In the following equation 7,
Vb is a reference wheel speed, and Kp and Kd are proportional constants of a proportional term and a differential term in the wheel speed feedback control.

## EQU7 ## Drfo = Kp * (Vb-Vwtfo) + Kd * d
(Vb-Vwtfo) / dt Drfi = Kp * (Vb-Vwtfi) + Kd * d (Vb-V
wtfi) / dt Drro = Kp * (Vb-Vwtro) + Kd * d (Vb-V
wtro) / dt Drri = Kp * (Vb-Vwtri) + Kd * d (Vb-V
wtri) / dt

In step 240, a control signal is output to the control valves 40FL, 40FR, 40RL, and 40RR of each wheel so that the control valve is switched to the second position. The control signals corresponding to the duty ratios Drfo, Drfi, Drro, and Drri are output to the on-off valves of
The supply and discharge of the accumulator pressure to and from the FL, 38FR, 38RL, and 38RR are controlled, thereby controlling the braking pressure of each wheel.

In this case, when the duty ratio is a value between the negative reference value and the positive reference value, the upstream open / close valve is switched to the second position and the downstream open / close valve is set to the first position. , The pressure in the corresponding wheel cylinder is held, and when the duty ratio is equal to or more than the positive reference value, the upstream and downstream open / close valves are controlled to the positions shown in FIG. When the accumulator pressure is supplied to the corresponding wheel cylinder, the pressure in the wheel cylinder is increased, and when the duty ratio is equal to or less than the negative reference value, the upstream and downstream open / close valves are switched to the second position. By the setting, the brake oil in the corresponding wheel cylinder is discharged to the low-pressure conduit 42, whereby the pressure in the wheel cylinder is reduced.

Next, an outline of the control of the damping force of the suspension, the control of the connection state of the center differential, and the control of the shift speed of the automatic transmission according to the illustrated embodiment will be described with reference to the flowcharts shown in FIGS. . 5 to 7
The control according to the flowchart shown in is also started by closing an ignition switch not shown in the figure,
It is repeatedly executed at a predetermined time interval.

In step 300 of the suspension control routine shown in FIG. 5, a signal indicating the flag Fs is read, and in step 310, the flag Fs is read.
It is determined whether or not s or the flag Fd is 1, that is, whether or not the turning behavior of the vehicle is unstable. If a negative determination is made, the process proceeds to step 330, and an affirmative determination is made. In step 320, the damping force of the four-wheel shock absorber is set to hard (high damping force) in step 320.

In step 330, the flag Fs is set to 1
It is determined whether or not a predetermined time has elapsed from the time when the flag Fd has changed to 0 or the time when the flag Fd has changed from 1 to 0 (in both cases, the later time). Returning to step 300, when an affirmative determination is made, in step 340, the damping force of the four-wheel shock absorber is controlled according to the running state of the vehicle according to a normal damping force control routine. The normal damping force control routine in this case may be any control routine known in the art as long as the damping force is controlled according to the running state of the vehicle. In this step 340, The damping force may be set to soft (low damping force).

In step 400 of the center differential control routine shown in FIG. 6, a signal indicating the flag Fd is read, and in step 410, it is detected by a wheel speed sensor (not shown). Based on the average value Nf of the rotational speeds of the left and right front wheels and the average value Nr of the rotational speeds of the left and right rear wheels, the drive torque distribution to the front wheels increases when Nr> Nf, and conversely, the rear wheels when Nr <Nf. The target clutch oil pressure Pc of the center differential 74 is calculated so that the drive torque distribution to the center differential 74 is increased.

In step 420, the flag Fd is set to 1
It is determined whether or not the target clutch hydraulic pressure Pc is 0 in step 430.
Is set to When a negative determination is made in step 420, a determination is made in step 440 as to whether or not a flag Ft set by an automatic transmission control routine described later is 1, and when an affirmative determination is made, The process proceeds to step 430, and proceeds to step 450 when a negative determination is made. In step 450, control is performed so that the clutch oil pressure of the center differential 74 becomes the target clutch oil pressure Pc. In this case, the increase or decrease of the hydraulic pressure is controlled to such an extent that the gradient does not disturb the behavior of the vehicle.

In step 500 of the automatic transmission control routine shown in FIG. 7, a signal indicating the flag Fs is read, and in step 510, a shift position sensor (not shown) reads the signal. Based on the detected shift position, it is determined whether or not the shift lever of the automatic transmission is in the D range. If a negative determination is made, at step 520, the gear position flag H, the counter value C, Flags Ft are set to 0, respectively. Note that 0 of the gear position flag H corresponds to the neutral position, and 1 to 4 correspond to the first, second, third, and overdrive gear positions, respectively.

When an affirmative determination is made in step 510, the gear position flag H is calculated in step 530 from a map corresponding to the graph shown in FIG.
At step 540, it is determined whether or not the flag Fs is 1. When the determination is affirmative, at step 550, the count value C of the counter is incremented by 1 and the flag H is set to 4. When a negative determination is made, the count value C and the flag Ft are reset to 0 in step 560.

In step 570, it is determined whether or not the count value C has exceeded a reference value Kc (a positive constant integer). If the determination is affirmative, the flag H is set to 0.
And the flag Ft is set to 1,
If a negative determination is made, the process proceeds directly to step 590. In step 590, control is performed so that the gear position of the automatic transmission 78 becomes the gear position corresponding to the flag H.
In this case, the hydraulic pressure at the time of shifting is gradually changed so that the driving torque does not change suddenly.

Thus, in the illustrated embodiment, the slip angle β and the slip angular velocity βd of the vehicle body are calculated in step 20, the spin value SV is calculated based on these in step 30, and the process proceeds to step 40. Then, the target slip ratio Rsfo of the turning outer front wheel is calculated according to the spin value SV, and in steps 50 to 70, the flag Fs is set to 1 when the turning behavior of the vehicle is unstable and the vehicle is in the spin state.

In step 80, the target yaw rate γt of the vehicle is calculated. In step 90, the drift value DV is calculated based on the target yaw rate γt and the actual yaw rate γ. In step 100, the drift value DV is calculated in accordance with the drift value DV. The target slip ratio Rdall of the entire vehicle is calculated, and in steps 110 to 130, when the turning behavior of the vehicle is unstable and the vehicle is in a drift-out state, the flag Fd is set to 1.

Then, in steps 140 and 150, the target slip rate Rdall and the target slip rate Rsf, respectively.
are distributed to each wheel, and the final target slip rates Rfo, Rfi, Rro,
Rri is calculated.

When the turning behavior of the vehicle is in a stable state, an affirmative determination is made in step 210 of the braking force control routine. Therefore, in this case, the control of the braking force by the behavior control of steps 220 and 230 is executed. Instead, the braking pressure of each wheel is controlled according to the amount of depression of the brake pedal 12 by the driver. In addition, a negative determination is made in step 310 of the suspension control routine and an affirmative determination is made in step 330, whereby the damping force of the four wheels is controlled according to the traveling state of the vehicle, and the step of the center differential control routine is performed. A negative determination is made in 420 and 440, whereby the vehicle is driven in the 4WD mode, and a negative determination is made in step 540 of the automatic transmission control routine, whereby the gear position of the automatic transmission is changed. Vehicle speed V and throttle opening T
Automatically controlled according to A.

On the other hand, when the turning behavior of the vehicle is in an unstable state such as spin, a negative determination is made in step 210, and steps 220 to 240 are executed to control the braking force by the behavior control. When the vehicle is in a spin state, the spin is reduced by giving an anti-spin moment to the vehicle, and when the vehicle is in a drift-out state, the vehicle is given a turning assist moment and decelerated. As a result, drift-out is reduced.

By making an affirmative determination in step 310 of the suspension control routine, the damping force of the four-wheel shock absorber is set to a hard value, and the support load of each wheel varies due to the load movement caused by the turning of the vehicle. Is reduced. An affirmative determination is made in step 420 of the center differential control routine, and the target clutch oil pressure Pc is set to 0 in step 430, whereby the vehicle is driven in the 2WD mode. An affirmative determination is made in step 540, and after a predetermined time has elapsed, in step 580, the flag H
Is reset to 0, whereby the gear position of the automatic transmission is switched to neutral, thereby reducing the inertia of the drive system.

Therefore, according to the illustrated embodiment, when the turning behavior of the vehicle becomes unstable, the damping force of the shock absorber is automatically set to hardware, so that the supporting load of each wheel due to the load movement is reduced. By reducing fluctuations and automatically reducing the inertia of the drive train, the effect of disturbance torque applied to the drive wheels by the drive train is reliably reduced, thereby controlling the braking force of each wheel necessary for behavior control. Power can be accurately controlled, and turning behavior can be accurately controlled.

For example, FIG. 11 shows an example of changes in the spin value SV, the damping force of the shock absorber, and the shift speed of the automatic transmission in the illustrated embodiment. In FIG. 11, assuming that the spin value SV exceeds the reference value SVo at time t1 and falls below the reference value at time t4 as shown in the figure, the flag Fs is set in the interval t1 to t4.
Becomes 1. As can be seen from FIG. 11, the damping force of the shock absorber is set to hard at time t1, and
At time t5 when a predetermined time elapses from time 4, the control is set to soft (normal control), so that the fluctuation of the support load of each wheel due to the load movement during the time t1 to t5 is reduced.

In particular, according to the illustrated embodiment, the software is not switched at time t4 when the spin value SV becomes equal to or less than the reference value SVo, but at time t5 when a predetermined time elapses from time t4. Then, since the vehicle is set to be soft when the turning behavior of the vehicle becomes sufficiently stable, it is possible to reliably prevent the vehicle body from turning back when the damping force is switched to soft.

In the illustrated embodiment, the damping force is switched from hardware to soft at time t5 when a predetermined time has elapsed from time t4.
Assuming that s is a positive constant, the damping force may be switched from hard to soft when the spin value SV becomes SVo-ΔSVs in the decreasing process.

The gear position of the automatic transmission is changed to the fourth speed at time t1, to the N range at time t2 after a predetermined time has elapsed from time t1, and to the D range at time t4. Thus, the inertia of the drive system is reduced. In either case, the hydraulic pressure of the automatic transmission is gradually changed, thereby reliably preventing the shift shock.

In particular, according to the illustrated embodiment, the shift speed is not switched from the D range to the N range at the time point t1, but is switched to the N range once after being switched to the fourth speed, so that the driving force can be reduced. Undesirable changes in the behavior of the vehicle due to sudden changes are reliably prevented.

In the illustrated embodiment, the shift speed is switched from the N range to the D range at the time point t4. However, in the process of decreasing the spin value SV, the throttle opening is increased. When the value is equal to or more than the predetermined value, the spin value SV is set to SVo + ΔSVt with ΔSVt being a positive constant as shown by a dashed line in FIG. 11 so as to reflect the driver's desire to accelerate.
At time t3, the gear position may be switched from the D range to the fourth speed, and at time t4 or later, the gear may be switched to the D range.

FIG. 12 shows an example of changes in the drift value DV and the drive mode of the vehicle in the illustrated embodiment. In FIG. 12, if the drift value DV becomes equal to or more than the reference value DVo at time t1 and becomes equal to or less than the reference value at time t4, the flag Fd becomes 1 in the section t1 to t4.

The driving mode of the vehicle is switched from 4WD to 2WD at t1, thereby reducing the inertia of the driving system and returning from 2WD to 4WD at time t4.
In this case, the hydraulic pressure of the clutch of the center differential is gradually changed for a while after time t1, so that 4WD is changed to 2WD.
And the hydraulic pressure of the clutch is gradually changed for a while after time t4, so that
The drive mode is gradually switched to WD, so that undesired changes in the behavior of the vehicle due to sudden changes in the drive mode are reliably prevented.

In particular, according to the illustrated embodiment, even if the drift value DV is not equal to or greater than the reference value, the spin value is equal to or greater than the reference value, and the shift speed of the automatic transmission is switched to neutral. An affirmative determination is made in step 440 of the center differential control routine of No. 6, and in step 430, the target clutch oil pressure Pc is set to 0.
Drive mode is set to 2WD from 4WD
And the inertia of the drive system is reduced, so that the spin state of the vehicle is effectively reduced as compared with a case where such control is not performed.

In the illustrated embodiment, only the damping force of the shock absorber is controlled as the suspension characteristic. However, the spring constant of the suspension spring may be controlled as the suspension characteristic. Both the damping force of the shock absorber and the spring constant of the suspension spring may be controlled.

In the illustrated embodiment, the suspension characteristic control, the center differential control, and the automatic transmission control are performed in accordance with the routines shown in FIGS. 5 to 7, respectively. Need not be performed, and one or two of these controls may be omitted.

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

For example, in the above-described embodiment, the automatic transmission can be switched to the N range by the control signal. However, the automatic transmission cannot be switched to the N range by the control signal. May be configured to be switched to the highest gear position in the D range.

[0073]

As is clear from the above description, according to the first aspect of the present invention, the turning limit of the vehicle is discovered, the target slip ratio of each wheel in accordance with the turning behavior of the vehicle
Is calculated, and the slip ratio of each wheel becomes the target slip ratio.
The turning of the vehicle is controlled by controlling the braking force of each wheel.
When the behavior is stabilized and the braking force of the wheels is controlled by the behavior control means, the suspension characteristics are set to the hard characteristics by the suspension characteristic control means, and the suspension of each wheel caused by the load movement is set. Since the fluctuation of the load is reduced, the braking force of the wheels can be controlled more accurately than in the case where the suspension characteristics are the soft characteristics, whereby the turning behavior can be controlled more accurately.

Further, according to the first aspect of the present invention, the suspension characteristic is set to the hard characteristic, so that the amount of wheel bounce is reduced and the contact of the wheel with the bump stopper is suppressed. Abrupt changes in load can be prevented, and for example, the output of an acceleration sensor that detects the acceleration of the vehicle body to detect the turning limit of the vehicle becomes an abnormal value due to the impact of the bound stopper. Thus, it is possible to prevent the turning limit from being erroneously detected.

[0075] According to the second aspect, the turning limit of the vehicle is discovered, the eyes of each wheel in accordance with the turning behavior of the vehicle
The target slip rate is calculated, and the slip rate of each wheel is set to the target slip rate.
The braking force of each wheel is controlled so that the
When the turning behavior of the vehicle is stabilized and the behavior control means controls the braking force of the wheels , the inertia of the drive system is reduced by the inertia reduction means, and the disturbance torque applied to the drive wheels from the drive system is reduced. Since the influence is reduced, the braking force of the driving wheels can be controlled with high accuracy, and thus the turning behavior of the vehicle can be controlled with high accuracy.

[0076] Particularly, according to the configuration of claim 3, drive the behavior control means is detected spin state as turning limit of the vehicle
When the braking force of the wheels is controlled, the inertia of the drive system is reduced by switching the shift speed of the automatic transmission to the neutral or the high speed by the inertia reduction means.
The influence of the disturbance torque applied to the drive wheels from the drive system can be reliably reduced, whereby the spin state of the vehicle can be reliably and accurately controlled.

According to the present invention, when the drift-out state is detected as the turning limit of the vehicle and the braking force of the wheels is controlled by the behavior control means, the inertia reduction means switches from the 4WD state to the 2WD state. This reduces the inertia of the drive train,
The influence of the disturbance torque applied to the drive wheels can be reliably reduced, whereby the drift-out state of the vehicle can be reliably and accurately controlled, and the vehicle is switched from the 4WD state to the 2WD state. Since the steering characteristic is changed in the oversteer direction, the drift-out state of the vehicle can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a braking device of one embodiment of a behavior control device according to the present invention.

FIG. 2 is a block diagram showing an electric control device of one embodiment of the behavior control device according to the present invention.

FIG. 3 is a flowchart illustrating a behavior control routine of the illustrated embodiment.

FIG. 4 is a flowchart illustrating a braking force control routine of the illustrated embodiment.

FIG. 5 is a flowchart illustrating a suspension control routine of the illustrated embodiment.

FIG. 6 is a flowchart illustrating a center differential control routine of the illustrated embodiment.

FIG. 7 is a flowchart illustrating an automatic transmission control routine of the illustrated embodiment.

FIG. 8 is a graph showing a relationship between a spin value SV and a target slip ratio Rsfo of a turning outer front wheel.

FIG. 9 is a graph showing a relationship between a drift value DV and a target slip ratio Rdall of the entire vehicle.

FIG. 10 is a graph showing a relationship among a vehicle speed V, a throttle opening TA, and a gear H of an automatic transmission.

FIG. 11 shows spin value S in the illustrated embodiment.
5 is a time chart showing an example of a change in V, a damping force of a shock absorber, and a shift speed of an automatic transmission.

FIG. 12 shows a drift value D in the illustrated embodiment.
5 is a time chart illustrating an example of a change in V and a drive mode of a vehicle.

[Explanation of symbols]

 10 Brake device 14 Master cylinder 18, 20, 26, 28 Brake hydraulic pressure control device 34 Oil pump 38FL, 38FR, 38RL, 38RR Wheel cylinder 40FL, 40FR, 40RL, 40RR Control valve 44FL, 44FR, 44RL, 44RR ... On-off valve 46FL, 46FR, 46RL, 46RR ... On-off valve 50 ... Electric control device 56 ... Vehicle speed sensor 58 ... Lateral acceleration sensor 60 ... Yaw rate sensor 62 ... Steering angle sensor 64FL-64RR ... Wheel speed sensor 70 ... For suspension control Electric control device 72 ... Suspension 74 ... Center differential 76 ... Electrical control device for center differential control 78 ... Automatic transmission 80 ... Electrical control device for automatic transmission control

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 6/00-6/06 B60G 17/015 B60T 8/24 B60T 8/58 B60K 17/28-17 / 36 B60K 23/00-23/08 F16H 1/28-1/48

Claims (6)

(57) [Claims] 1. A means for detecting a turning limit of a vehicle, and detecting a turning limit of the vehicle according to a turning behavior of the vehicle when the turning limit of the vehicle is detected.
Calculate the target slip ratio of each wheel, and check that the slip ratio of each wheel is
Behavior control means for stabilizing the turning behavior by controlling the braking force of each wheel to achieve the target slip ratio; and setting the suspension characteristics to hard characteristics when the braking force of the wheels is controlled by the behavior control means. A behavior control device for a vehicle, comprising: Means for detecting a turning limit of the vehicle, and detecting the turning limit of the vehicle in accordance with the turning behavior of the vehicle when the turning limit of the vehicle is detected.
Calculate the target slip ratio of each wheel, and check that the slip ratio of each wheel is
A behavior control means for stabilizing the turning behavior by controlling the braking force of each wheel to achieve the target slip ratio; and reducing the inertia of the drive system when the braking force of the wheel is controlled by the behavior control means. A vehicle behavior control device having an inertia reduction unit. 3. The vehicle behavior control device according to claim 2,
When the spin state is detected as the turning limit of the vehicle and the braking force of the wheels is controlled by the behavior control means, the inertia reducing means switches the shift speed of the automatic transmission to the neutral or high speed to reduce the inertia of the drive system. A vehicle behavior control device characterized by reduction. 4. A vehicle behavior control device according to claim 2,
The inertia reducing means reduces the inertia of the drive system by switching from a 4WD state to a 2WD state when a drift-out state is detected as a turning limit of the vehicle and a braking force of a wheel is controlled by the behavior control means. Vehicle behavior control device. (5) 4. The vehicle behavior control device according to claim 1, wherein:
And the behavior control means detects a turning limit of the vehicle.
Sometimes the target control amount of the whole vehicle according to the turning behavior of the vehicle
Is calculated, and the target control amount of the entire vehicle is calculated as the turning behavior of the vehicle.
Target slip of each wheel by allocating to each wheel according to
A vehicle behavior control device for calculating a rate. 6. The vehicle behavior control device according to claim 1,
The suspension characteristic control means detects the turning limit of the vehicle.
After a predetermined period of time has passed since the
It is possible to return the sprinkle characteristics to the normal characteristics from the hard characteristics.
And a behavior control device for a vehicle.