JPH03112757A - Turn action control device for vehicle - Google Patents

Abstract

PURPOSE:To improve high speed turn performance by setting a difference in braking force between both turn direction inner and outer side wheels so as to generate yaw moment for assisting turn action during the high speed turn action of a vehicle such as performing so-called heel-and-toe operation. CONSTITUTION:A vehicle, as is generally known, is accelerated by stepping in an accelerator pedal AP further decelerated by stepping in a brake pedal BP. Here a step-in of the accelerator pedal AP is detected by a means A. While similarly, a step-in of the brake pedal BP is detected by a means B. Further a turn condition of the vehicle is detected by a means C. In accordance with each output signal from the above described means A to C, when both the accelerator pedal AP and the brake pedal BP are stepped in, a difference is set by a means D in braking force between both turn direction inner and outer side wheels IW, AW so as to generate yaw moment for assisting turn action of the vehicle.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the turning behavior of a vehicle, particularly the so-called heel-and-toe operation in which the driver depresses the accelerator pedal while depressing the brake pedal in order to make a high-speed turn. The present invention relates to a device that controls turning behavior during rotation.

(Prior art) In vehicles that tend to understeer, especially when entering a curved road at high speed, the traveling trajectory tends to bulge outward in the direction of the turn, and to prevent this, the driver turns the steering wheel more. Or, if this is not enough, it is necessary to brake the vehicle by depressing the brake pedal to cause a load shift, and to increase the front wheel cornering force by increasing the front wheel load accordingly.

By the way, although the above-mentioned braking operation is a brake pedal operation to correct the direction of travel of the vehicle, it also decelerates the vehicle and at the same time causes a decrease in the engine speed, making it difficult to re-accelerate. worsen performance. In this case, a skilled driver must use the above-mentioned driving technique of pressing down on the accelerator pedal as well to prevent the engine speed from dropping when operating the brake pedal (commonly known as heel-and-toe, but this is not the case with cars equipped with automatic transmissions). This is called "left foot braking" because the brake pedal is pressed with the free left foot instead of the right foot.
).

However, even if lever driving techniques can prevent a drop in engine speed, it is impossible to decelerate the vehicle, and it is inevitable that the speed at which the vehicle enters a curved road or the speed at which it travels through a curved road will decrease, and it enters a curved road at high speed. There is no way I can run through this.

On the other hand, as a technology for controlling turning behavior, there has been a conventional
Japanese Patent No. 279976 proposes a device that applies braking force to the inner rear wheel in the turning direction during turning to assist in generating a yaw rate in the turning direction of the vehicle. This device reduces the braking force to the inner rear wheel at high vehicle speeds.
The aim is to increase the size at low vehicle speeds to achieve both turning stability at high speeds and maneuverability at low speeds.

(Problem to be solved by the invention) However, with the lever device, only the primary control that can be expected is to reduce the yaw rate if the vehicle speed is high while turning, and increase the yaw rate if the vehicle speed is low. There is no hope for control that will allow the vehicle to enter and run through this area.

In order to enable such control, the present invention creates a yaw moment that promotes turning by differentiating the braking force between the inner and outer wheels in the turning direction while the driver performs a heel-and-toe operation. It is an object of the present invention to provide a turning behavior control device in which a brake pedal operation directly contributes to correction of a turning direction rather than through deceleration of a vehicle.

(Means for Solving the Problems) For this purpose, the turning behavior control device of the present invention, as conceptually shown in FIG. accelerator detection means for detecting depression of the pedal; brake detection means for detecting depression of the brake pedal; turning state detection means for detecting the turning state of the vehicle; and inner and outer wheel braking force difference setting means for differentiating the braking force between the inner and outer wheels in the turning direction so as to generate a yaw moment that promotes the turning depending on the turning state while both of the wheels are being depressed. It is what it is.

(Function) When a high-speed turn is desired by depressing both the accelerator pedal and the brake pedal, the inner and outer wheel braking force difference setting means responds to signals from the accelerator detection means and the brake detection means, which detect the depression of these pedals, respectively. According to the turning state of the vehicle detected by the state detecting means, the braking force of the wheels is varied between the inner and outer sides in the turning direction so as to generate a yaw moment that promotes the turning.

This allows the vehicle to trace a turning trajectory desired by the driver by depressing both the accelerator pedal and the brake pedal. In addition, since the depression of the brake pedal directly contributes to correction of the turning direction rather than through deceleration of the vehicle, the above objective can be achieved without significant deceleration of the vehicle, and it is possible to reach the curved road at high speed. You can rush in and run through this.

In addition, the above-mentioned correction of the turning direction reduces the amount of corrective steering of the steering wheel, reducing the burden on the driver, and
This provides more leeway for steering to correct disturbances in turning behavior, which is greatly beneficial for safety.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the turning behavior control device of the present invention.
IR is left and right front wheels, 2L, 2R is left and right rear wheels, 3L,
3R indicates the front wheel cylinder, and 4L and 4R indicate the rear wheel cylinders, respectively. Also, 5 is a brake pedal, and 6 is a master cylinder that simultaneously outputs the same hydraulic pressure to system 7 for the front two wheels and system 8 for the two rear wheels when the brake pedal is depressed, and the master cylinder hydraulic pressure for system 7 is branched. Series 7L,
Wheel cylinder 3L via 7R.

3R and brakes the front wheels IL and IR, and the master cylinder hydraulic pressure of system 8 passes through branched systems 8L and 8R to wheel cylinders 4L and 4R, where it brakes the rear wheels 2L and 2R.

In contrast to such a normal front and rear split two-system hydraulic brake system, in this example, systems 7L, 7R18L, and 8R are respectively opened to the pressure increasing position shown in the figure, where these systems are normally opened and the master cylinder hydraulic pressure is directed to the wheel cylinder. Insert solenoid valves ILL, IIR, 12L, and 12R that maintain the

These valves are all similar 3-position solenoid valves, and when the current to the corresponding solenoid (electromagnetic valve drive current) i, ~i4 is 0, the above pressure increase position is achieved, and when the current i, ~i4 is oil, all The boat is cut off and the hydraulic pressure in the wheel cylinder is maintained at a pressure holding position, and when the current + 1 "" + 4 is 4A, the wheel cylinder is connected to the corresponding reservoir tank 13.1.
4, the vehicle is assumed to be in a depressurizing position where the hydraulic pressure in the wheel cylinder is reduced.

The reservoir tanks 14, 15 are connected to the suction ports of pumps 16, 17 which are appropriately driven by a common motor 15, and the brake fluid temporarily stored in the reservoir banks 13, 14 during the above depressurization is returned to the accumulator 19, 20, and the system is Provided for reuse in 7 and 8.

The electromagnetic valve drive currents i, to i4 are individually determined by a controller 21, which includes wheels IL and IR.

Signals from wheel speed sensors 22 to 25 that detect rotational speeds ω1 to ω4 of 2L and 2R, respectively, signal A from the accelerator switch 26 that detects depression of the accelerator pedal (not shown), and detection of depression of the brake pedal 5. signal B from the brake switch 27 and the steering wheel 3.
The signals from the steering angle sensor 28 which detects the steering angle θ of 0 (shown singly in FIG. 4) are respectively input.

The controller 21 executes the control program shown in FIG. 3 based on this input information to realize the turning behavior control aimed at by the present invention.

First, in steps 31 to 33, each wheel IL, IR, 2
L.

2R's rotational speed ω1 to ω4, steering angle θ, accelerator signal A, and brake signal B are read respectively. In the next step 34, the vehicle speed ■ is calculated from the wheel rotational speeds ω1 to ω4. In this calculation, since the rotational speed ω, ω2 of the front wheel, which is a non-driving wheel, approximately corresponds to the vehicle speed V during non-braking when the brake pedal 5 is not depressed, when the front wheel radius is R, V= The vehicle speed V is determined by calculating R, (ω, +ω2)/2. During braking, however, the number of revolutions of the front wheels does not necessarily correspond to the vehicle speed, so a pseudo vehicle speed is determined using a method commonly used in anti-skid control, and this is used as the vehicle speed V.

In step 35, the accelerator signal A and the brake signal B
Heel-and-toe (when the driver depresses both the accelerator pedal and the brake pedal) depends on whether both are 1 or not.
Check whether the left foot brake is being operated.

If this operation is not performed, the turning behavior control according to the present invention is not necessary, so the solenoid valve drive currents 11 to i4 are all set to 0 in step 36 and outputted in step 40. In this case, solenoid valves 11L, IIR, 12L,
12R is at the pressure increasing position shown in the figure, and the wheel cylinder hydraulic pressure of each wheel is made to depend on the hydraulic pressure from the master cylinder 6, so that normal braking is possible.

Heel and toe (left foot brake) at step 35
If it is determined that the vehicle is in operation, the turning behavior control aimed at by the present invention is performed as follows. That is, in step 37, the solenoid valve drive current +1+IJ (when turning left) or 12+14 (when turning right) of the inner wheel in the turning direction is set to 0, and the braking force (wheel cylinder hydraulic pressure) of the inner wheel is shown in FIG. Just leave it to the force of pressing the brake pedal.

Therefore, the braking force of the outer wheel in the turning direction is reduced,
In order to generate a yaw moment in the turning direction due to the difference in braking force with the inner wheel, the turning state is checked in step 38 to determine in which region the turning state is occurring. This determination is naturally made based on the steering angle θ and the vehicle speed V, but as shown in FIGS. 4 and 5, the turning angle from the neutral position of the steering wheel 30 is ±θl (+ indicates left (- means right steering) and a small steering angle range less than ±θ1
Above, medium steering angle range less than ±θ2, and ±θ2 or more, ±θ.

(θ is the steering limit) The vehicle speed is divided into 3 large steering angle ranges as shown in Figure 5. The vehicle speed range is divided into 3 regions: 12 and 12 or higher vehicle speed regions. The above judgment is based on the combinations of these steering angle ranges and vehicle speed ranges, a and b as shown in Figure 5.
, c, and d-order Jf ranges, it is determined in which region the turning state is occurring.

In the next step 39, the area determined in this way (
The degree of braking force restriction on the outer wheels in the turning direction in order to obtain the yaw moment (behavior correction in the turning direction) required by the driver by heel-and-toe (left foot braking) operation, depending on the turning condition), that is, the relevant Wheel solenoid valve drive current j2+
14 (when turning left) or jl+13 (when turning right) is looked up from the table data in FIG. This table data shows the outer wheel solenoid valve drive current iz+ for each region (turning state) determined in step 38.
For how many m5ec should L or 11+13 be kept at 0^, solenoid valves 11L, 12L or IIR, 12R on the outer wheels should be set to the pressure increasing position, and for how many m5ec should the cycle be kept at 2A and the same solenoid valve should be set to the pressure holding position? The pattern is determined, and the higher the time ratio of the pressure holding position, the more the braking force of the outer wheels is restricted and the larger the yaw moment in the turning direction is generated. Then, the time ratio of the pressure holding position is determined so that this yaw moment corresponds to the turning behavior correction amount required by the heel-and-toe (left foot brake) operation. Fifth
As shown in the figure, the vehicle speed is V. , the steering angle is θ. To explain the turning state at point X as an example, this turning state is c
Therefore, as is clear from Fig. 6, the outer wheel solenoid valve driving current is OA for 3 m5ec, and
The pattern shown in FIG. 7, which repeats the cycle of adding m5ec, is decided upon.

Solenoid valve drive current i, ~i determined in step 37.39
4 is the corresponding solenoid valve 11L, IIR,
12L.

It is output to 12R and brakes the corresponding wheels individually. By the way, as is clear from the above, the braking force (wheel cylinder hydraulic pressure) on the inner wheel in the turning direction has a value corresponding to the depression force of the brake pedal 5 as shown in FIG. As illustrated in the figure, since the wheel cylinder hydraulic pressure is made smaller than the value corresponding to the depression force of the brake pedal 5, the vehicle receives a yaw moment in the turning direction and is encouraged to turn, resulting in heel-and-toe operation. This allows you to make the desired turn.

However, pressing the brake pedal during heel-and-toe operation does not decelerate the vehicle, but directly generates a yaw moment, that is, contributes to correcting the turning direction. You can enter a curved road and drive through it.

Note that in the above example, the braking force is commonly limited for the left or right front and rear wheels, but it goes without saying that it is also possible to control only the front wheels or only the rear wheels so that there is a difference in braking force between the inner and outer wheels. Also, heel and toe (left foot brake)
During operation, if the steering wheel is turned back and a turn is made in the opposite direction, it will be necessary to suddenly reduce the wheel cylinder fluid pressure, which had been set high, but for this purpose, the solenoid valve on the corresponding side must be temporarily turned off. You can achieve your goal by placing it in the reduced pressure position. Furthermore, the wheel cylinder hydraulic pressure to be increased can be made higher than the mask cylinder hydraulic pressure by means of a separately provided pressure increasing means, thereby generating an even greater yaw moment.

In addition, in determining the turning state of the vehicle, it is of course possible to perform region determination using a combination of the steering amount and vehicle lateral acceleration instead of using the combination of the steering amount and vehicle speed as shown in FIG. It is.

FIG. 8 shows another example of the present invention, and this example shows front wheel cylinder piping 7L of a two-system hydraulic brake system.

A normally open electromagnetic on-off valve 41L, 411'l is inserted only in 7R, and the opening/closing of this valve is controlled by the controller 42, so that a simple structure can be obtained to obtain the same effect as in the previous embodiment. The controller 42 includes an accelerator switch 2.
Signal A from 6, signal B from brake switch 27,
A signal from the steering angle sensor 28 and a signal from a vehicle speed sensor 43 that detects the vehicle speed (2) are input.

During a heel-and-toe (left foot brake) operation where A=1 and B=1, the controller 42 is in a turning state where the steering angle θ is greater than the set value and the vehicle speed ■ is also greater than the set value. The same effect as in the above embodiment can be obtained by a program that closes the on-off valve 41L or 41R of the outer front wheel in the turning direction IL (turning right) or IR (turning left) to generate a yaw moment in the turning direction. do it like this. However, in this example, the control is rough and it is difficult to obtain fine control of turning behavior, but the configuration can be significantly simplified and lowered in cost.

(Effects of the Invention) Thus, as described above, the turning behavior control device of the present invention, during a turn such as performing a heel-and-toe (left foot brake) operation, controls the turning behavior in the inner and outer directions in the turning direction so as to generate a yaw moment that promotes the turning. Since the wheel braking force is configured to vary, the brake operation directly contributes to correcting the turning direction rather than through vehicle deceleration, making it possible to correct the turning direction without significantly reducing vehicle speed. This makes it possible to enter and traverse curved roads at high speed.

In addition, such correction of the turning direction can reduce the amount of corrective steering of the steering wheel, which contributes to reducing the burden on the driver, and also provides leeway for steering to correct disturbances in turning behavior, which is greatly beneficial for safety. be.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the turning behavior control device of the present invention, Fig. 2 is a system diagram showing an embodiment of the device of the present invention, Fig. 3 is a flowchart showing a control program for control on the same side, and Fig. 4 is a steering Corner division diagram, Figure 5 is a region diagram of the turning state, Figure 6 is a pattern diagram of the outer wheel solenoid valve drive current for each region, and Figure 7 is an operation time chart of turning behavior control by the system in Figure 2. , FIG. 8 is a system diagram similar to FIG. 2 showing another example of the present invention. IL, IR...Front wheel 2L, 2R...
Rear wheels 3L, 3R, 4L, 4R...Wheel cylinder 5...Brake pedal 6...Master cylinder ILL, IIR, 12L, 12R...Solenoid valve 1
3, 14...Reservoir tank 15...Motor 16.17...Pump 19, 20...Accumulator 21...Controller 22-25...Wheel speed sensor 26...Accelerator inch 27. ...Brake switch 28...Steering angle sensor 30...Steering wheel 41L, 41R...Solenoid on-off valve 42...Controller 43...Vehicle speed sensor @I Figure 3 Figure 4 Figure 5 @ 6 Figure 7

Claims (1)

[Claims] 1. In a vehicle that accelerates when the accelerator pedal is depressed and decelerates when the brake pedal is depressed, the present invention includes an accelerator detection means that detects the depression of the accelerator pedal, a brake detection means that detects the depression of the brake pedal, and a turning state that detects the turning state of the vehicle. and a state detection means, and in response to the signals from these means, while both the accelerator pedal and the brake pedal are depressed, a yaw moment that promotes the turning is generated according to the turning state between the inside and outside in the turning direction. A turning behavior control device for a vehicle, comprising means for setting a difference in braking force between inner and outer wheels for differentiating wheel braking force.