JP2663712B2 - Vehicle control device - Google Patents

Abstract

PURPOSE:To restrain spinning of a vehicle by controlling the torque of each rear wheel while deciding a desired slip ratio in such a manner that when a slip angle detected exceeds a set value the larger the slip angle the larger the desired slip ratio of an inside rear wheel and the smaller the desired slip ratio of an outside rear wheel. CONSTITUTION:A slip angle detection means 2 is provided for detecting the slip angle of the body of a vehicle and a desired slip ratio is decided by a desired slip ratio deciding means 4 in such a manner that at least when the slip angle detected exceeds a set value, the larger the slip angle detected the larger the desired slip ratio of an inside rear wheel and the smaller the desired slip ratio of an outside rear wheel. The torque of each rear wheel is controlled by a rear wheel torque control means 6 in such a manner that the actual slip ratio of each rear wheel approximates the desired slip ratio decided. At least when the vehicle starts to spin, the rotary moment of each wheel is controlled in such a manner that frictional forces between each rear wheel and the road surface are generated in such a direction as effectively resisting the spin moment of the body of the vehicle thereby restraining spinning of the body.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device, and more particularly to a vehicle control device capable of favorably suppressing the occurrence of spins in which a rear portion of a vehicle body swings outward when the vehicle turns. It is.

2. Description of the Related Art A vehicle control device that controls the rotational torque of wheels so that the lateral force of the vehicle (force in the width direction of the vehicle) becomes an appropriate value is disclosed in Japanese Patent Application Laid-Open No.
It is already known from -253559. The control device described in this publication discloses a ratio Ff / δf, Fr / δr between a slip angle δf, δr and a lateral force Ff, Fr for a front wheel and a rear wheel,
Or, a means for calculating the ratios ΔFf / Δδf, ΔFf / Δδr of the change amounts, and when the calculated ratios become smaller than the positive limit value K, a braking force is applied to the wheels, or the output of the engine is reduced. Means for lowering the traveling speed of the vehicle by lowering the vehicle speed. The wheel slip angle is the angle formed by the actual direction of travel of each wheel with respect to the direction perpendicular to the axis of rotation of the wheel, and the greater the wheelslip, the greater this angle. The running condition is stable while the lateral force increases in proportion to the increase in the wheel slip angle, but if the lateral force does not increase in spite of the increase in the wheel slip angle, the running condition of the vehicle will be unstable. Become. The above-mentioned control device avoids the occurrence of such running state instability by reducing the running speed of the vehicle.

Problems to be Solved by the Invention However, since the conventional vehicle control device is not designed to actively generate a moment against the spin moment of the vehicle body, the occurrence of spin is sufficiently suppressed sufficiently. I couldn't.

SUMMARY An advantage of some aspects of the invention is to provide a vehicle control device capable of favorably suppressing generation of spin.

As shown in FIG. 1, a vehicle control device according to the present invention includes a slip angle detecting means 2 for detecting a slip angle of a vehicle body, and a vehicle non-braking operation in which a brake operation is not performed. At least when the detected slip angle of the vehicle body exceeds the set value, the target value of the wheel slip ratio, which is a positive value when driving the wheel and a negative value when braking, is set when the vehicle turns out of the left and right rear wheels. The inner rear wheel is determined to have a positive value whose absolute value increases according to the slip angle of the vehicle body, and the outer rear wheel is determined to have a negative value whose absolute value increases according to the slip angle of the vehicle body. And the rear wheel torque control means 6 for controlling the rotational torque of each rear wheel so that the actual slip rate of each rear wheel approaches each target slip rate. Be composed.

In one embodiment of the present invention, the target slip ratio determining means is:
The target slip ratio of each rear wheel is determined by calculating each of the circles centered on the center of gravity of the vehicle when the vehicle is viewed from directly above while the direction of the total frictional force between each rear wheel and the road surface is both facing the inside of the turn. This is a mode in which the direction is determined so as to face a tangent line at the center of the rear wheel.

In the vehicle control device according to the present invention, the target slip ratio determining means 4 outputs a positive value at the time of driving the wheels and a negative value at the time of braking, at least in a state where the slip angle of the vehicle body exceeds the set value when the vehicle is not braking. The target value of the slip ratio of the wheels is a positive value whose absolute value increases according to the slip angle of the vehicle body for the inner rear wheel, and the absolute value increases according to the slip angle of the vehicle body for the outer rear wheel To a negative value.

For example, when the set value of the slip angle of the vehicle body is set to a relatively large value, and when the actual slip angle of the vehicle body exceeds the set value, the control of the spinning speed of the vehicle is suppressed at the expense of suppressing the spin. If this is to be done, the total friction with the road surface at both the inner and outer rear wheels, i.e. the cornering force and the wheel travel direction force (the force in the actual travel direction of the wheel, usually the traction and The sum of the traction resistance and the forces in both the positive and negative directions called the acceleration and deceleration forces is referred to as the wheel movement direction force). The slip ratio of both rear wheels is determined so as to be directed to the direction of the tangent at the center of each rear wheel of a circle centered at. The larger the slip angle of the vehicle body, which is the slip angle at the center of gravity of the vehicle, the greater the slip angle of the rear wheels. Also, after the 18th
As described in detail with reference to FIGS. 21 to 21, the direction of the total frictional force generated between the wheel and the road surface is determined by the slip angle and the slip rate of the wheel, and the direction of the total frictional force is determined by the slip rate. The target slip ratio determining means 4 determines that the total frictional force of both the inner rear wheel and the outer rear wheel is directed to the inside of the turn, as shown in FIG. 25, for example. If the target slip ratio of both rear wheels is determined so as to be directed to the tangent direction of each rear wheel, the total frictional force of both wheels will most effectively oppose the spin moment, and the occurrence of spin will be improved. Can be suppressed.

In addition, when the set value of the slip angle of the vehicle body is set relatively small, it is possible to suppress the occurrence of spin while controlling the traveling speed. In this case, the target slip ratio is determined. The means 4 determines the target slip ratios of the rear wheels so that the total frictional force between the wheels and the road surface is inclined forward or backward by a predetermined angle from the direction of the tangent line of each rear wheel. If the direction of the total frictional force is tilted forward, the vehicle is driven, and if the direction is tilted backward, the vehicle is braked and the traveling speed is controlled.

As described above, when the control of the traveling speed is performed together with the suppression of the spin, the target slip ratio determining unit 4 may determine the target slip ratio in the entire region of the slip angle of the vehicle body or in many regions. Good.

In any of the above cases, the target slip ratio determining means 4
Determines the target slip ratio of the inner rear wheel to a positive value whose absolute value increases in accordance with the slip angle of the vehicle body (slip angle at the center of gravity of the vehicle), as represented by the graph in FIG. 23, for example. The target slip ratio of the rear wheels is determined to be a negative value whose absolute value increases according to the slip angle of the vehicle body.In the conventional traction control or anti-skid control, the magnitude of the vehicle body slip angle is This is in contrast to the fact that the slip rate was set to a constant value regardless.

It should be noted that, with regard to the relationship between FIG. 23 and FIG. 25 used in the above description, of the two graphs in FIG. 23, the upper graph showing that the target slip ratio always takes a positive value The lower graph representing the target slip ratio of the inner rear wheel and indicating that there is a region where the target slip ratio has a negative value represents the target slip ratio of the outer rear wheel.
In FIG. 25, this corresponds to the case where the target slip ratio of the right rear wheel RR as the inside rear wheel is 50%, and the target slip ratio of the left rear wheel RL as the outside rear wheel is -20%.

The target slip ratio is determined as described above, and the rear wheel torque control means 6 controls the rotational torque of each rear wheel so that the actual slip ratio of each rear wheel approaches the determined target slip ratio. To reduce the rotational torque, the braking force on the rear wheels may be increased, or the output of the engine may be reduced. Conversely, in order to increase the rotational torque, the engine output may be increased, and the braking force on the rear wheels may be reduced.

As described above, according to the present invention, at least when the vehicle starts spinning when the vehicle is not braking, the total frictional force between each rear wheel and the road surface effectively reduces the spin moment of the vehicle body. Since the rotational torque of each rear wheel is controlled so as to be generated in the opposite direction, the generation of spin is favorably suppressed, and an effect of facilitating steering of the vehicle is obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, 10 is a left front wheel, 12 is a right front wheel, 14 is a left rear wheel, 16 is a right rear wheel, front wheels 10 and 12 are steering wheels, rear wheels 14 and
16 is a drive wheel. The vehicle control device according to the present embodiment includes a hydraulic brake device 18 for applying a braking force to these wheels, a drive device 20 for applying a driving force, and a control device 22 for controlling the two devices 18 and 20.

The hydraulic brake device 18 includes a master cylinder 26 that generates a hydraulic pressure according to the depression force of the brake pedal 24. The master cylinder 26 has two pressurizing chambers, and brake fluid pressure generated in each pressurizing chamber passes through main fluid passages 28, 30 to left and right front wheel cylinders 32, 34 and left and right rear wheel cylinders 36, 38. Is transmitted. Hydraulic pressure control valves 40, 42, 44 and 46 are provided at three positions corresponding to the respective wheel cylinders 32, 34, 36 and 38, and these hydraulic pressure control valves are provided from the respective wheel cylinders 32, 34, 36 and 38. Valve 4
The brake fluid discharged to the reservoirs 48, 50 via 0, 42, 44, and 46 is returned to the master cylinder 26 by the pumps 52, 54. The hydraulic brake device 18 further comprises
A hydraulic pressure source 60 including a pump 56 and an accumulator 58 is provided. The hydraulic pressure of the hydraulic pressure source 60 is supplied to front wheel cylinders 32 and 34 and rear wheel cylinders 36 and 38 via hydraulic passages 62 and 64, respectively. Two on-off valves 66, 68 and 70, 72 are provided in order to supply the hydraulic pressure of the above to the front wheel cylinders 32, 34 and the rear wheel cylinders 36, 38 alternatively. 74 is a proportioning / bypass valve.

The drive unit 20 includes an engine 80, a transmission 82, and the like, and drives the left and right rear wheels 14, 16, and the output of the engine 80 is controlled by an electric throttle valve 86 opened and closed by a motor 84.

The control device 22 includes a CPU 90, a ROM 92, a RAM 94, an input processing circuit 96, and an output processing circuit 98. The hydraulic pressure control valves 40, 42,
Each of the valves 44, 46 and the on-off valves 66, 68, 70, 72 is an electromagnetic valve, and is connected to the output processing circuit 98. Also pump 5
2, 54 and 56 drive motors are also connected to the output processing circuit 98. The output processing circuit 98 further includes a throttle valve 86
Motor 84 is also connected.

On the other hand, the input processing circuit 96 includes a brake switch 104 for detecting depression of the brake pedal 24, a pressure sensor 106 for detecting the hydraulic pressure of the accumulator 58, wheels 10, 12, 14, and 16
Rotation sensors 108, 110, 112 and 11 for detecting the rotation speed of
4.Accelerator sensor 1 that detects the rotation angle of the accelerator pedal
16, an opening sensor 118 for detecting the opening of the throttle valve 86, an engine rotation sensor 120 for detecting the rotational speed of the engine 80, and a speed sensor 122 for detecting the speed of the transmission 82. The input processing circuit 96 further includes a front / rear speed sensor 124, a lateral speed sensor 126, and a lateral G sensor.
128, a yaw rate sensor 130, and a steering angle sensor 132 are connected. Front / rear speed sensor 124 and lateral speed sensor 126
Are respectively fixed to the vehicle body and detect the longitudinal and lateral velocities between the vehicle body and the road surface by using the Doppler effect or the like. The lateral G sensor 128 and the yaw rate sensor 1
Numerals 30 are respectively fixed to the vehicle body and detect the lateral acceleration and the yaw rate of the vehicle body. The steering angle sensor 132 detects a rotation operation angle of the steering wheel.

FIGS. 3A to 3E are block diagrams of the vehicle control device shown in FIG. 2 focusing on functions. Fig. 3 (a)
The yaw rate detecting means 140 is constituted by the yaw rate sensor 130 and a part of the input processing circuit 96 for obtaining a digital value representing the yaw rate based on the output signal thereof. Similarly, brake operation detecting means 142, steering angle detecting means
144, front / rear speed detecting means 146, lateral speed detecting means 147, right front wheel speed detecting means 148, left front wheel speed detecting means 15 in FIG.
0, the right rear wheel speed detecting means 152 and the left rear wheel speed detecting means 154 in FIG. 3C, the transmission gear ratio detecting means 156 and the engine speed detecting means 158 in FIG. The brake switch 104, the steering angle sensor 132, the front / rear speed sensor 124, the lateral speed sensor 126, the rotation sensors 108 to 114, the gear position sensor 122, the engine rotation sensor 120, and the presence / absence of a brake operation based on their output signals, the steering angle , The longitudinal speed of the vehicle, the lateral speed of the vehicle, the wheel speed of each wheel 10-16, the speed of the transmission 82,
An input processing circuit 96 for obtaining a digital value representing the number of revolutions of the engine 80 and the like.

A computer mainly composed of the CPU 90 performs arithmetic processing based on the detection results of the respective detecting means, and based on the results, the brake control means 160, 162, 164 and 166 in FIG. 3 (e) and the throttle control in FIG. 3 (d). The control means 168 is controlled. The brake control means 160 is configured by the hydraulic pressure control valve 42, the on-off valves 66, 68, and the like, and a portion of the output processing circuit 98 that controls those valves, and controls the hydraulic pressure of the right front wheel cylinder 34. Brake control means 162,164
And 166 are similarly wheel cylinders 32, 38 and 36
This is for controlling the hydraulic pressure. Throttle control means 168
Is a motor 84 of the throttle valve 86 and an output processing circuit.
98, a part for controlling the motor 84, and a part of an input processing circuit 96 for obtaining a digital value representing the opening degree of the throttle valve 86 based on the opening degree sensor 118 of the throttle valve 86 and an output signal thereof.

The other means shown in FIGS. 3A to 3E are constituted by a CPU 90, a ROM 92 and a RAM 94, and the ROM 92 stores the program shown in FIG.

Of the CPU 90, the ROM 92, and the RAM 94, step S1 (hereinafter, referred to as step S1)
Simply represented by S1. (The same applies to the other steps). The part that executes the slip angle calculation constitutes the front wheel slip angle calculation means 170, the rear wheel slip angle calculation means 172, and the vehicle center-of-gravity point slip angle calculation means 173 in FIG. 3 (a). The details of S1 are shown in FIG.

Also, the part that executes each wheel reference wheel speed calculation step S2 constitutes a reference wheel speed calculation means 174, the details of which are shown in FIG.

The part that executes the target slip ratio calculation step S3 constitutes the front wheel left / right target slip ratio calculation means 176 and the rear wheel left / right target slip ratio calculation means 178.
It is shown in the figure.

The part that executes the target wheel speed calculation step S4 constitutes the front wheel partial brake control target wheel speed calculation means 180, the rear wheel left / right brake control target wheel speed calculation means 182, and the throttle control target wheel speed calculation means 184. Is shown in FIG.

The steps for executing the wheel speed deviation calculating step S5 are the right front wheel brake wheel speed deviation calculating means 186, the left front wheel brake wheel speed deviation calculating means 188, and the right rear wheel brake wheel speed deviation calculating in FIGS. 3 (b) and 3 (c). Means 190, left rear wheel brake wheel speed deviation calculating means 192, right rear wheel throttle wheel speed deviation calculating means 19
4, constituting the left rear wheel throttle wheel speed deviation calculating means 196, the details of which are shown in FIG.

The part that executes the target brake hydraulic pressure calculation step S6 constitutes the target brake hydraulic pressure calculation means 200, 202, 204 and 206 in FIG. 3 (e), the details of which are shown in FIG.

The part that executes the brake control step S7 constitutes the brake control means 160, 162, 164 and 166 of FIG. 3 (e), the details of which are shown in FIG. 11 and FIG. FIG. 12 representatively shows details of the FR (right front wheel) hydraulic pressure control step of S709 in FIG.
(Left front wheel) hydraulic control, RR (right rear wheel) hydraulic control in S720, RL (left rear wheel) hydraulic control in S724, and the like are performed in the same manner.

The portion for executing the throttle control gain and integral initial value calculating step S8 is a proportional gain calculating means 208 shown in FIG.
And the integral initial value calculating means 210, the details of which are shown in FIG.

The part for calculating the target throttle opening and executing the control step S9 is the grip-side wheel speed deviation selecting means 21 shown in FIG.
2. The target engine torque calculating means 214 and the target throttle opening calculating means 216 are constituted, and details thereof are shown in FIG.

Hereinafter, each step will be sequentially described in detail with reference to FIG. 15 illustrating a state where the vehicle is turning right.

First, in the slip angle calculation of S1, as shown in FIG. 5, the longitudinal speed Vx and the lateral speed Vy of the vehicle body are read in S101 and S102, and based on them, the traveling direction speed Vsa of the vehicle body is calculated in S103. Then, in S104, the center-of-gravity point slip angle Sag is calculated. Then, S105 and S
At 106, the yaw rate Yr and the steering angle Sta are read, respectively. From the read steering angle Sta, the actual front wheel tire angles Stafr and Stafl of the right front wheel 12 and the left front wheel 10 are determined in S107. Steering angle Sta and actual front tire angle Staf
There is a relationship shown in FIG. 16 between r and Stafl, and the actual front wheel tire angle is determined based on a table showing this relationship. The direction of the angle is positive when viewed clockwise when the vehicle is viewed from above.

Next, in S108, the rear wheel slip angles Sarr, Sarl of the right rear wheel 16 and the left rear wheel 14 are calculated from the front-rear speed Vx, the lateral speed Vy, and the yaw rate Yr read in S101, S102, and S105, and in S109, Actual front wheel tires Stafr, Stafl calculated in front-rear speed Vx, lateral speed Vy, yaw rate Yr, and S107
From the front wheel slip angle Safr, Saf of the front right wheel 12 and the front left wheel 10
l is calculated. In the formulas of S108 and S109, the symbols A and B represent the center of gravity of the vehicle in the front-rear direction (this moves with the occupants, but uses the center of gravity in a standard state such as, for example, two-seater riding) from the front wheels and the rear wheels. Distance to the wheel, symbol L
Is the distance from the center of gravity of the vehicle to the wheels in the lateral direction.

The calculation of the reference wheel speed of each wheel in S2 is performed by executing the steps shown in FIG. First, in S201 and S202, the yaw rate Yr, the front-rear speed Vx, and the lateral speed Vy are read, and in S203, the actual front wheel tire angle Staf calculated in S107.
r, Stafl is read. Then, in S204, the speed of each wheel assuming that there is no circumferential slip in the right front wheel 12, the left front wheel 10, the right rear wheel 16 and the left rear wheel 14 by using the read values is the reference wheel of each wheel. Speed Vsfr, Vsfl, Vsr
Calculated as r, Vsrl.

The calculation of the target slip ratio in S3 is performed by executing the steps in FIG. First, in S301, S104 and
Slip angle Sag of vehicle center of gravity calculated in S108, slip angles Safr and Safl of left and right front wheels, and slip angle Sar of left and right rear wheels
r and Sarl are read, and in S302, the brake switch
It is determined based on the signal from 104 whether or not braking is being performed. If braking is being performed, S303 and S304 are executed, and if not, S305 and S306 are executed.

In S303, the slip angles Sarl, Sa of the left and right rear wheels 14,16
The rear wheel target slip rates Tslprr and Tslprl are determined from rr and the curve of the target slip rate during braking shown by the solid line in FIG. Actually, the relationship between the slip angle and the target slip ratio represented by a solid line is tabulated, and the target slip ratio is determined using the table. Conventionally,
In the anti-skid control for preventing the wheel slip from becoming excessive during braking, the slip ratio is set to a substantially constant negative value regardless of the slip angle. As the angle increases, the target slip ratio is determined to be a large value, and in a region where the slip angle is large, the target slip ratio is determined to be a positive value.

FIG. 18 shows that when the slip angle of the wheel is 4 degrees, +10
It is a figure which shows the direction in which the maximum total friction force (the vector sum of the cornering force and the wheel moving direction force) is obtained at each slip ratio from 0% to -100%, and the magnitude of the maximum total friction force by a vector. 19 to 21 are similar diagrams when the slip angles are 12, 20, and 50 degrees, respectively. In these figures, the cornering force is maximized when the direction of the maximum total frictional force is in a direction perpendicular to the actual moving direction of the wheel, and the slip when the cornering force is maximized for each slip angle. The dashed line in FIG. 17 plots the rates.
Therefore, if the slip ratio is controlled to the value indicated by the one-dot chain line, the cornering force is maximized, but in this case, the force in the wheel movement direction becomes zero. Both when braking and driving the vehicle, a wheel moving direction force is required. At the time of braking, the cornering force is smaller than the slip rate at which the cornering force is maximized by a predetermined amount (an amount at which a wheel moving direction force having an appropriate magnitude is obtained). It is necessary to set the slip rate as a target slip rate, and to set the slip rate larger than the slip rate at which the cornering force is maximum when braking is not performed by a predetermined amount as the target slip rate. The curve shown by the solid line in FIG. 17 represents the target slip ratio at the time of braking determined in consideration of this, and the curve shown by the broken line is the same as at the time of braking without braking. This represents the target slip ratio when the target slip ratio is determined based on the concept. As described above, the slip ratio may be controlled based on the same concept even when the brake is not applied. However, in the present embodiment, the target slip ratio is controlled by another method described later with particular emphasis on prevention of spin generation when the brake is not applied. Is to be determined.

Since the rotational torque of the rear wheel can be performed both by lowering the engine output and increasing the brake fluid pressure, the target slip ratios Tslprr and Tslprl of the rear wheel determined as described above are determined by the engine. The target slip ratios Tslprrb and Tslprlb for the rotational torque control by the brake are determined as values larger than the target slip ratios Tslprrb and Tslprlb by the constant value Kslp. Therefore, when the slip ratio of the rear wheels decreases over time as shown in FIG. 22 during braking, the actual slip ratio becomes the target slip ratio Tslprrb, Tslprl.
While it is larger than b, the wheel rotation torque is reduced by both the braking action and the engine output, and the target slip rates Tslprrb, Tslprlb and the target slip rates Tslprr, Tslp
Between rl and rl, the wheel rotation torque is reduced due to a decrease in the engine output, and when the slip rate becomes smaller than the target slip ratios Tslprr, Tslprl, the engine output is increased.

After the execution of S303, in S304, the right front wheel 12 and the left front wheel
Target slip rates Tslpfr and Tslpfl of 10 are determined. Since the wheel rotation torque is not controlled for the front wheels by controlling the engine output, the determined target slip ratio is used as a target slip ratio for brake control.

The above control is performed when braking is being performed at the time of execution of S302.
In step S306, the target slip ratio of the rear wheels is determined, and in step S306, the target slip ratio of the front wheels is determined. In this case,
The target slip ratios of the rear wheels and the front wheels are determined based on the relationships shown in FIGS. 23 and 24, respectively.

In order to prevent the occurrence of spins in which the rear wheels slip outside the turning locus during non-braking, as shown in FIG. 25, the frictional force between the left and right rear wheels 14, 16 and the road surface is determined by the center of gravity of the vehicle. It is desirable to orient in the direction that most effectively opposes the centered spin moment. If the slip ratio at which the maximum frictional force is in the direction is set as the target slip ratio, it is possible to prevent the rear portion of the vehicle body from swinging outside the turning radius. FIG. 23 takes this into consideration and also considers the fact that the larger the slip angle at the center of gravity of the vehicle, the greater the slip angle of the rear wheels. The target slip ratio between the vehicle and the inner rear wheel is defined with respect to the slip angle at the center of gravity of the vehicle, and is actually tabulated.

In order to effectively prevent spin, the total frictional force of the right and left rear wheels 14, 16 is effectively countered to the spin moment as described above, while the left and right front wheels 10, 12 are moderately skid to cancel the body spin. It is desirable to make it. It is desirable that a moment that balances with the moment of the rear wheel be obtained at the front wheel in order to keep the vehicle attitude stable. In consideration of this, Fig. 24 shows the front left and right wheels 10,1
The target slip ratio is determined for each slip angle of 2, and the larger the slip angle at the center of gravity of the vehicle and the larger the front wheel slip angle, the smaller the slip ratio of the front wheels (the negative value The value is large), which is also tabulated.

In the traction control for preventing the wheel slip from becoming excessive when the vehicle is accelerating, the slip ratio is conventionally set to a constant positive value, whereas in the present embodiment, the front wheel and the rear wheel are different. From the viewpoint, the target slip ratio is determined, and both can be changed according to the magnitude of the slip angle at the center of gravity of the vehicle.

The calculation of the target wheel speed in S4 is performed by executing each step of FIG. First, in S401, the reference wheel speeds Vsfr, Vsfl, Vsrr, and Vsrl are read into the right front wheel 12, the left front wheel 10, the right rear wheel 16, and the left rear wheel 14 determined in S204, and in S402, determined in S304 or S306. Right front wheel 12 and left front wheel 10
And the front wheel target slip rates Tslpfr and Tslpfl are read. In S403, target wheel speeds Vnfr and Vnfl of the right front wheel 12 and the left front wheel 10 are calculated based on the read values. Similarly, in S404, the target slip ratios Tslprr, Tslpr of the right rear wheel 16 and the left rear wheel 14 determined in S303 or S305.
l, and the target slip ratio Tslprrb, Tsl for brake control
prlb is read, in S405, the rear wheel slip ratio and the reference wheel speeds Vsfr, Vsfl, Vsrr, Vsr read in S401.
The target wheel speeds Vnrr, Vnr of the right rear wheel 16 and the left rear wheel 14 from l
1 and the brake control target wheel speeds Vnrrb and Vnrlb are calculated.

The calculation of the wheel speed deviation in S5 is performed by executing the steps in FIG. First, in S501, the target wheel speeds calculated in S403 and S405 are read, and in S502, the actual wheel speeds Vwfr, Vwfl, Vwrr of the right front wheel 12, the left front wheel 10, the right rear wheel 16 and the left rear wheel 14 are read. And Vwrl are read, and the wheel speed deviations Vdfr, Vdfl, Vdrr, Vdrl of the right front wheel 12, the left front wheel 10, the right rear wheel 16 and the left rear wheel 14, and the right rear wheel 16 and the left rear Wheel speed deviations Vdrrb and Vdrlb for rotational torque control by braking the wheels 14 are calculated.

The calculation of the target brake fluid pressure in S6 is performed by executing each step of FIG. First, in S601, a wheel speed deviation for brake control of each wheel is read. For the right front wheel 12 and the left front wheel 10, Vdfr and Vdfl calculated in S503 are read, and for the right rear wheel 16 and the left rear wheel 14, the same applies to S503.
Vdrrb and Vdrlb calculated in are read. In S602, a target gain hydraulic pressure Bpfr for the right front wheel 12 is calculated by multiplying the wheel speed deviation Vdfr for the right front wheel 12 by a predetermined gain Gbp. In S603, it is determined whether or not the target brake fluid pressure Bpfr is positive. If the decision result is YES, S604 is skipped and the brake fluid pressure becomes S
The value calculated in 602 is left as it is, but the determination result is NO
If so, it is changed to 0 in S604. Similarly, in steps S605 to S607, S608 to S610, and S611 to S613, target brake fluid pressures Bpfl, Bprr, and Bprl of the left front wheel 10, the right rear wheel 16, and the left rear wheel 14, respectively, are calculated. However, rear wheel 1
Hunting may occur if the brake fluid pressures are controlled completely independently, because the valves 4 and 16 are connected to each other by a differential device. Therefore, the value obtained by subtracting the product of the rate of change Drl, Drr of the wheel speed on the opposite side and the gain Gd from the value obtained by multiplying the wheel speed deviation Vdrr, Vdrl by the gain Gbp is set as the target brake fluid pressure, and hunting is performed. Is prevented. For example, when the brake fluid pressure of the right rear wheel 16 is increased and its rotation speed is reduced, the brake fluid pressure of the left rear wheel 14 is also increased by an amount corresponding to the decrease rate.

Using the target brake fluid pressure determined as described above, S7
Brake control is performed. This control is performed by executing each step of FIG. First, in S701, it is determined whether or not all of the target brake fluid pressures are 0,
If the result of the determination is YES, S737 and S738 are executed, the master cylinder 26 is communicated with the wheel cylinders 32-38, while the hydraulic pressure source 60 is shut off, and the hydraulic pressure control valves 40-46 are The pressure is increased. When the brake pedal 24 is depressed, the brake is normally operated.

On the other hand, the target brake fluid pressures Bpfr, Bpfl, Bprr, Bpr
If any of l is not 0, the determination result in S701 is NO, and it is determined in S702 whether or not braking is being performed. If braking is being performed, S703 and subsequent steps are executed, and if braking is not being performed, S725 and subsequent steps are executed.

In S703, it is determined whether the target brake fluid pressures of the front wheels 10, 12 are both 0. If the result of the determination is YES, the on-off valve 66 is opened, the on-off valve 68 is closed in S704, and the master Cylinder 26 and front wheel cylinders 32,3
Communication with 4 is maintained. On the other hand, if the determination result in S703 is NO, the communication state between the master cylinder 26 and the front wheel cylinders 32, 34 is maintained in S705, and the target brake fluid pressure Bpfr of the right front wheel 12 is positive in S706. It is determined whether there is. If the result of the determination is NO,
In S707, the hydraulic pressure control valve 42 for the right front wheel 12 is maintained in the increased pressure state.If the result of the determination is YES, the hydraulic pressure control valve 44 for the left front wheel 10 is switched to the holding state in S708. Then, in S709, the hydraulic pressure of the front wheel cylinder 34 is controlled by controlling the hydraulic pressure control valve 42 for the right front wheel 12.

This hydraulic control is performed by executing each step of FIG. First, in S740, the difference between the current target brake fluid pressure and the previous target brake fluid pressure is multiplied by a constant K to calculate the increase / decrease time tfr for the right front wheel 12, and in S741, the positive / negative of the increase / decrease time tfr is calculated. , 0 is determined. Judgment result is 0
In step S742, the hydraulic pressure control valve 42 for the right front wheel 12 is switched to the holding state. When the result of the determination is positive, after the hydraulic pressure control valve 42 is switched to the pressure increasing state in S743, S744 and S745 are repeatedly executed, and it is waited that the increase / decrease time tfr becomes 0. . During that time, pressure increase is performed. If the result of the determination is negative, in S747, the hydraulic pressure control valve 42 is switched to a reduced pressure state, and S748 and S749 are repeatedly executed to reduce the pressure for the increase / decrease time tfr. Then, when the pressure increase or pressure decrease of the increase / decrease time tfr is completed, the hydraulic pressure control valve 42 is switched to the holding state in S746, and one execution of S709 is completed.

In S710 to S713, the left front wheel is similar to S706 to S709.
The hydraulic pressure control for the ten front wheel cylinders 32 is performed, and the pressure is increased or decreased for a time corresponding to the target brake hydraulic pressure Bpfl. Similarly, the brake fluid pressure is controlled for the rear wheels 14, 16 by executing S714 to S724.

On the other hand, if braking is not being performed at the time of determination in S702, it is determined in S725 whether or not both of the target brake fluid pressures of the front wheels 10, 12 are 0. If the determination result is YES, the master cylinder 26 is determined in S726. But front wheel cylinder 3
2, and the hydraulic pressure source 60 is shut off.

On the other hand, if the target brake hydraulic pressure Bpfr or Bpfl is not 0, both the hydraulic pressure control valves 40 and 42 for the front wheels 10 and 12 are kept in a holding state, and in S728, the pump 52 The pump 54 is also operated because it is common), the hydraulic pressure source 60 is connected to the hydraulic pressure control valves 40 and 42, and the master cylinder 26 is shut off. Thereafter, in S729 and S730, the hydraulic pressure control is performed on the right front wheel 12 and the left front wheel 10, respectively, and the pressure is increased or decreased for a time corresponding to the target brake hydraulic pressures Bpfr, Bpfl.

The same hydraulic control is performed on the rear wheels 14 and 16 in S731 to S736.

The calculation of the throttle control gain and the integral initial value in S8 is performed by executing the steps shown in FIG. S80
In step S802, the engine speed Ne and the speed are read, and in step S803, it is determined whether the speed is changed. If the result of the determination is NO, S804 and S805 are skipped, but if YES, the proportional gain Gbt
Is determined, and an integral initial value Ttrq (0) is calculated in S805.

The determination of the proportional gain Gpt in S804 is performed using a map represented by the graph of FIG. When the gear position of the transmission 82 is changed, the inertia with respect to the engine 80 changes, and the response frequency of the wheel speed to the change in the throttle opening changes. As the reduction ratio becomes smaller, the response becomes worse and the control becomes unstable. To avoid this, a map is created so that the proportional gain Gpt becomes smaller as the reduction ratio becomes smaller. The calculation of the initial integration value in S805 is as follows: Ttrq (0) = {Ttrq (0) + Git × IVdth} × old gear ratio / new gear ratio where Git: integral gain IVdth: throttle control wheel speed deviation described later This is done using the integral of Vdth. Each time the gear ratio of the transmission 82 is changed, the characteristics of the drive device 20 change. The change affects the determination of a target engine torque Ttrq described later by the proportional gain Gpt and the integral initial value Ttrq (0). It is done like this.

The calculation and control of the target stroll opening in S9 are performed by executing the steps in FIG. First, in S901, the wheel speed deviations Vdrr and Vdrl of the right rear wheel 16 and the left rear wheel 14 are read,
In S902, they are compared, and the smaller one, that is, the wheel speed deviation of the grip-side drive wheel is set as the throttle control wheel speed deviation Vdth. The set wheel speed deviation Vdth, the proportional gain Gpt and the integral initial value Ttrq (0) determined in S804 and S805, the deviation integral IVdth calculated in the next step S904, and the constant integral In S903, the target engine torque Ttrq is calculated from the gain Git. The engine torque is controlled based on the wheel speed deviation of the rear wheel on which the torque is insufficient, and the torque is controlled by the brake on the opposite rear wheel because the torque becomes excessive. Become.

Subsequent to S903, the deviation integration is performed in S904, and the engine speed Ne is read in S905. From the read engine speed Ne and the target engine torque Ttrq calculated in S903, a target throttle opening Tth is calculated in S906. There is a relationship shown in FIG. 27 between the engine speed Ne, the target engine torque Ttrq, and the target throttle opening Tth, and the target throttle opening Tth is calculated by an interpolation method using a table representing this relationship. It is. The target throttle opening Tth is S90
The motor 84 is controlled such that the actual throttle opening output at 7 and detected by the opening sensor 118 is equal to the target throttle opening Tth.

By controlling the brake hydraulic pressure of the hydraulic brake device 18 and the throttle opening of the drive device 20 as described above, the rotational torque of each of the wheels 10 to 16 is increased, and the slip ratio of each of the wheels is braked. During the specific braking, control is performed so as to approach the target slip ratio shown in FIGS. 23 and 24. Thereby, at the time of braking, both the wheel movement direction force of all the wheels and the cornering force have an appropriate magnitude, and the requirements of both deceleration and directional stability are satisfied, and the vehicle is braked while turning well and braking. On the other hand, when braking is not performed, the generation of spin is favorably prevented.

As is clear from the above description, in this embodiment, the vehicle center-of-gravity point slip angle calculating means 173 shown in FIG.
This constitutes the slip angle detecting means 2. That is, the slip angle detecting means 2 is constituted by the front / rear speed sensor 124, the lateral speed sensor 126, and the portion of the control device 22 that executes S101 to S104. The target slip ratio is calculated by the brake operation detecting means 142 and the rear wheel left / right target slip rate calculating means 178 of FIG. 3A, that is, by the brake switch 104 and the part of the control device 22 that executes S301, S302 and S305. The determining means 4 is configured. Then, the reference wheel speed calculating means 174 and the rear wheel left / right brake control target wheel speed calculating means 18 shown in FIG.
2, throttle control target wheel speed calculating means 184, target brake hydraulic pressure calculating means 204 and 206 in FIG. 3 (e), brake control means 164 and 166 and each means in FIGS. 3 (c) and 3 (d), The rear wheel torque control means 6 is constituted by the brake device 18, the drive device 20, and the part of S2, S4 to S9 of the control device 22 that executes each step relating to the rear wheel.

FIG. 28, FIG. 29 and FIG. 30 show another embodiment of the present invention. Parts other than those shown in these figures are the same as those in the above embodiment.

In the present embodiment, as is apparent from FIG. 28, the yaw rate detecting means 140 is connected to the front wheel left / right target slip rate calculating means 176, and as shown in FIG. 29, the front wheel target slip rate calculated in S306. It is characterized in that Tslpfr and Tslpfl are corrected based on the yaw rate Yr.

In step S307, the yaw rate Yr is read, and in step S308, the correction coefficient Ksy is determined from the correction coefficient table in which the graph shown in FIG. 30 is tabulated. In step S309, the correction coefficient Ksy is determined by the front wheel target slip ratio Tslpf determined in step S306.
The target front wheel slip rate is corrected by multiplying r and Tslpfl.

Since the absolute value of yaw ray | Yr | indicates the degree of spin of the vehicle, as | Yr | is larger, the front wheel target slip rates Tslpfr, Tslpf
If l is corrected to a large value, the responsiveness to the spin of the vehicle is improved, and the steering is further facilitated.

It should be noted that the front wheel target slip ratios Tslpfr and Tslpfl can be corrected by using the differential value of the yaw rate instead of the yaw rate Yr itself.

A few embodiments of the book have been described above, but these are merely examples, and various modifications and alterations can be made based on the knowledge of those skilled in the art.
It goes without saying that the present invention can be implemented in an improved mode.

[Brief description of the drawings]

FIG. 1 is a block diagram conceptually showing the configuration of the present invention. FIG. 2 is a system diagram showing a vehicle control device according to one embodiment of the present invention. FIGS. 3 (a), (b), (c),
(D) and (e) are diagrams in which the vehicle control device is divided into blocks focusing on functions. FIG. 4 to FIG.
4 is a flowchart illustrating a control program stored in a ROM 92 of FIG. FIG. 15 is a diagram showing the center of gravity of the vehicle during a right turn and the direction of the slip angle of each wheel. FIG. 16 is a graph showing the relationship between the steering angle of the steering wheel and the actual steering angles of the left and right front wheels. FIG. 17 is a graph showing a relationship between a wheel slip angle and a target slip ratio during braking. FIGS. 18 to 21 are diagrams showing the direction and magnitude of the maximum total frictional force when the wheel slip angles are 4, 12, 20, and 50 degrees, respectively. FIG. 22 is a diagram for explaining the determination of the target slip ratio in FIG. 23rd
FIG. 24 and FIG. 24 are diagrams showing the relationship between the vehicle center-of-gravity point slip angle and the target slip rates of the rear wheels and the front wheels at the time of non-braking, respectively. FIG. 25 is a diagram for explaining the determination of the target slip ratio in FIGS. 23 and 24. FIG. 26 is a graph showing a relationship between an engine speed and a gear position and a proportional gain for calculating a target engine torque. No.
FIG. 27 is a graph showing the relationship among the engine speed, the target engine torque, and the target throttle opening. 28 and 29 are diagrams corresponding to FIGS. 3 (a) and 7 in another embodiment of the present invention, respectively. FIG. 30 is a diagram showing a correction coefficient table used in the above another embodiment. 6 is a graph showing the contents of the above. 10: Left front wheel, 12: Right front wheel 14: Left rear wheel, 16: Right rear wheel 18: Hydraulic brake device 20: Drive device, 22: Control device 32: Left front wheel cylinder 34: Right front wheel cylinder 36: Left Rear wheel cylinder 38: Right rear wheel cylinder 40, 42, 44, 46: Hydraulic pressure control valve 56: Pump, 58: Accumulator 60: Hydraulic pressure source 66, 68, 70, 72: Open / close valve 80: Engine, 82: Speed change 84: motor, 86: throttle valve 104: brake switch 106: pressure sensor 108, 110, 112, 114: rotation sensor 116: accelerator sensor 118: opening degree sensor 120: engine rotation sensor 122: gear position sensor 124: front / rear speed sensor 126: lateral speed sensor 128: Lateral G sensor 130: Yaw rate sensor 132: Steering angle sensor

Claims (2)

(57) [Claims] 1. A slip angle detecting means for detecting a slip angle of a vehicle body, wherein at least when the detected slip angle of the vehicle body exceeds a set value when the vehicle is not braked without a brake operation, the wheel is driven. The target value of the wheel slip ratio, which is a positive value and a negative value during braking, is set to a positive value, the absolute value of which is increased according to the slip angle of the vehicle body, for the inner rear wheel, which is the inside of the left and right rear wheels when the vehicle is turning. And a target slip ratio determining means for determining a negative value whose absolute value increases in accordance with the slip angle of the vehicle body, and an actual slip ratio of each rear wheel. And a rear wheel torque control means for controlling a rotational torque of each rear wheel so as to approach a target slip ratio. 2. The target slip ratio determining means determines the target slip ratio of each rear wheel when the direction of the total frictional force between each rear wheel and the road surface is directed toward the inside of the turn and the vehicle is viewed from directly above. 2. The method according to claim 1, further comprising: determining a circle centered on the center of gravity of the vehicle in a direction of a tangent at the center of each rear wheel.
The vehicle control device according to claim 1.