Fluid-pressure and analogous brake systems – Speed-controlled – Odd condition or device detection
Reexamination Certificate
2000-03-08
2001-11-13
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Odd condition or device detection
C303S182000, C180S282000
Reexamination Certificate
active
06315373
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a roll control device of a vehicle such as an automobile, and more particularly, to a roll control device of a vehicle equipped with means for managing a sudden failure of means for detecting a rolling condition of the vehicle during a braking for the purpose of suppressing a rolling of the vehicle, the braking being controlled based upon the output of the rolling condition detection means.
2. Description of the Prior Art
As a roll control device of a vehicle such as an automobile, there is known a device described in Japanese Patent Laid-open Publication 6-297985 by the same applicant as the present application, wherein a parameter for judging a liability of the vehicle to roll down is calculated based upon a height of the center of gravity and a roll angle of the vehicle, so that a braking force is applied to a selected wheel or wheels for decelerating and suppressing the vehicle from rolling down when the parameter exceeds a predetermined threshold value. By such a roll control device, the vehicle is automatically suppressed from rolling so much as to approach a limit of rolling down during a turning, thereby relieving the driver from the requirement of a keen attention about a rolling condition or a control of vehicle speed during a turning.
In a roll control of a vehicle such as above, it is generally required to detect at least a lateral acceleration of the vehicle as a parameter for detecting a rolling condition of the vehicle for judging a requirement of the roll suppress control. When the lateral acceleration sensor does not operate normally, the roll control device does not operate normally. Therefore, when a failure has occurred in the lateral acceleration sensor, or more generally, in the rolling condition detection means including sensors such as the lateral acceleration sensor, the roll control device should no longer be operated. Further, if a failure of the lateral acceleration sensor or the rolling condition detection means occurred during the operation of the roll control device, the operation of the roll control device will have to be stopped as soon as possible.
In the known roll control devices, including that of the above-mentioned laid-open publication, when the roll control ends, the braking applied for the roll suppress purpose is generally rapidly canceled so that the vehicle is resumed as soon as possible to the normal control of the driver. When the braking is canceled according to a normal brake ending schedule at a normal end of the brake control that the rolling condition of the vehicle subsided below a predetermined threshold value, a cancellation of the braking at a relatively high speed will cause no shock or instability of the vehicle. However, if the braking is canceled according to the same normal brake ending schedule from a relatively large vehicle rolling condition due to an occurrence of a failure of a lateral acceleration sensor or rolling condition detection means during the operation of the roll suppress control, there would occur a substantial shock or instability of the vehicle.
SUMMARY OF THE INVENTION
In view of the above-mentioned problem in the abrupt cancellation of the braking due to a failure of a lateral acceleration sensor or rolling condition detection means during the operation of the roll suppress control, it is a primary object of the present invention to provide a roll control device of a vehicle improved with regard to its manageability of a sudden failure of a lateral acceleration sensor or rolling condition detection means during its operation of the roll suppress control.
According to the present invention, the above-mentioned primary object is accomplished by a roll control device of a vehicle having a front pair and a rear pair of wheels, a brake system, and a steeling system for steeling the vehicle, comprising:
means for detecting a rolling condition of the vehicle;
means for controlling the brake system for applying a braking for suppressing the rolling condition when the rolling condition increases beyond a first threshold value and to end the application of the braking according to a normal brake ending schedule when the rolling condition subsides below a second threshold value lower than the first threshold value;
means for judging an abnormal condition for ending the application of the braking before the rolling condition subsides below the second threshold value; and
means for modifying the brake system control means so as to end the application of the braking according to an abnormal brake ending schedule which ends the application of the braking at a less quickness than the normal brake ending schedule when the abnormal condition judgment means judge the abnormal condition.
By the application of the roll suppress braking being ended at a less quickness at the time of abnormal ending than in the normal ending, even when the roll suppress braking is ended starting at a relatively high roll condition before it is subsided by the roll suppress control, a shock or an instability of the vehicle due to an abrupt cancellation of the roll suppress braking is avoided.
According to an embodiment of the roll control device of the present invention, the brake system control means may end the application of the braking according to the normal brake ending schedule such that the braking is decreased at a first rate, while the brake system control means end the application of the braking according to the abnormal brake ending schedule such that the braking is decreased at a second rate smaller than the first rate.
In the above embodiment, the second rate may be made smaller as the rolling condition of the vehicle at a moment at which the abnormal condition judgment means judge the abnormal condition is higher.
According to another embodiment, the brake system control means may end the application of the braking according to the normal brake ending schedule such that the braking is decreased gradually by starting at a moment at which the rolling condition subsides below the second threshold value, while the brake system control means end the application of the braking according to the abnormal brake ending schedule such that the braking is decreased gradually by starting as substantially delayed from a moment at which the abnormal condition judgment means judge the abnormal condition.
In the above embodiment, the time for delaying the start of the ending of the application of the braking may be made larger as the rolling condition at the moment at which the abnormal condition judgment means judge the abnormal condition is higher.
According to still another embodiment, the brake system control means may end the application of the braking according to the normal brake ending schedule such that the braking is decreased at a first rate, while the brake system control means end the application of the braking according to the abnormal brake ending schedule such that the braking is decreased at a second rate smaller than the first rate for a predetermined period, and then the braking is decreased at a third rate larger than the second rate.
In the above embodiment, the predetermined period for decreasing the braking at the second rate may be made longer as the rolling condition at a moment at which the abnormal condition judgment means judge the abnormal condition is higher.
The roll control device according to the present invention may comprise a lateral acceleration sensor for detecting lateral acceleration of the vehicle as a parameter for detecting the rolling condition of the vehicle, and the abnormal condition judgment means may judge the abnormal condition when the lateral acceleration sensor is judged as not operating normally.
An abnormal condition of such lateral acceleration sensor may be judged, when a vehicle speed sensor for detecting running speed of the vehicle and a yaw rate sensor for detecting yaw rate of the vehicle are available, according to if the lateral acceleration detected by the lateral acceleration sensor is di
Nagae Akira
Yamada Noritaka
Nguyen Xuan Lan
Oberleitner Robert J.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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