Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-06-24
2001-01-23
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S072000, C701S038000, C180S197000
Reexamination Certificate
active
06178368
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for controlling the rolling of four-wheeled vehicles, and more particularly, to such a roll control device for four-wheeled vehicles that controls the rolling without disturbing the turning course thereof.
2. Description of the Prior Art
The rolling of a vehicle body of a four-wheeled vehicle during its turn running can be suppressed by decelerating the vehicle or increasing the radius of curvature of the turning course, i.e. drifting out the vehicle, or doing both of these, because the lateral centrifugal force acting at the vehicle body which causes its rolling is proportional to the ratio of the square of the running speed of the vehicle to the radius of curvature of the turning course. Therefore, various roll control devices ever proposed are based upon the principle of decelerating the vehicle or drifting out the vehicle or doing both. A deceleration of a vehicle is of course available by actuating its brake system, while a drifting out of a vehicle is available by selectively actuating such a brake system that is adapted to be able to apply a controlled braking force to each one of the wheels independently of the other.
However, as well known in the art, a braking applied to a wheel necessarily causes a change the slip of the wheel against the road surface, particularly when the vehicle is running along a curved course so critically as to require a roll suppress control. Therefore, there is a problem that the braking for a roll suppress control induces instabilities of the course of driving, including an unintended increase of the radius of curvature of the turning course.
SUMMARY OF THE INVENTION
Therefore, it is a primary object of the present invention to provide a roll control device for four-wheeled vehicles which controls the rolling of the vehicle in reference to a turning course of the vehicle.
In order to accomplish the above-mentioned primary object, the present invention proposes a device for controlling a rolling of a vehicle during a turning, the vehicle having a vehicle body, a pair of front wheels and a pair of rear wheels, a steering system, and a brake system for applying a braking to each wheel of at least one of the front pair and the rear pair of wheels independently of the other of the pair, the device comprising:
means for detecting a speed Vx of the vehicle;
means for detecting a steering angle &thgr; of the steering system;
means for calculating a turning radius R of the turning based upon at least the steeling angle &thgr; detected by the steering angle detection means and the vehicle speed Vx detected by the vehicle speed detection means;
means for calculating a target roll suppress quantity Qrs so as to be indicative of the degree of need of a roll suppress control;
means for calculating a target deceleration Gxt of the vehicle and a target yaw torque Twt of the vehicle such as
Gxt=
(
R/
2
Vx
)
Qrs
Twt=
(
I/
2
Vx
)
Qrs
wherein I is an inertial yaw moment of the vehicle;
means for calculating a slip ratio of each wheel of the at least one pair of front or rear wheels so as to attain the target deceleration Gxy of the vehicle and the target yaw torque Twt of the vehicle; and
means for operating the brake system so as to accomplish the calculated slip ratio at each wheel of the at least one pair of front or rear wheels.
As will be appreciated from the following descriptions, when the brake system capable of applying a braking to each whel of at least one of the front pair and the rear pair of wheels independently of the other of the pair is operated so as to decelerate the vehicle to the above-mentioned target deceleration Gxt, while applying the above-mentioned target yaw torque Twt to the vehicle, the rolling of the vehicle body is controlled while maintaining the vehicle to turn along a curved course having a radius of curvature such as R calculated to be due based upon the operation of the steering system and the vehicle speed.
Such a device may further comprise means for detecting a lateral acceleration of the vehicle body, and the target roll suppress quantity calculation means may calculate the target roll suppress quantity Qrs so as to increase at least according to an increase of the magnitude of the lateral acceleration detected by the lateral acceleration detection means.
In order to further improve the operation of such a roll control device as described above, the device may further comprise means for detecting a roll rate of the vehicle body, and the target roll suppress quantity calculation means may calculate the target roll suppress quantity Qrs to be proportional to a sum of a difference between the magnitude of the lateral acceleration detected by the lateral acceleration detection means and a limit value predetermined therefor and an amount which increases in proportion to the roll rate detected by the roll rate detection means.
By such an arrangement, the roll control device can apply a braking for a roll suppress control to a pertinent wheel or wheels with a forecasting estimation of a rolling of the vehicle body, so as thereby to more effectively suppress a rolling of the vehicle body.
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Nguyen Tan
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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