Fluid-pressure and analogous brake systems – Speed-controlled – With failure responsive means
Reexamination Certificate
1999-12-15
2001-10-23
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
With failure responsive means
C303S147000, C303S112000, C303S183000, C303S182000, C303S181000, C303S171000
Reexamination Certificate
active
06305760
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention related to a behavior control of a vehicles such as an automobile, and more particularly, to an improvement of such a behavior control device with regard to the reliability of its normal operation periled by a failure of a longitudinal acceleration sensor incorporated therein.
2. Description of the Prior Art
A wide variety of behavior control devices have been developed in the field of the modern so-called vehicle stability control, the art of controlling a running behavior of a vehicle such as an automobile against such instabilities as a spin, a drift out and others, the control being based upon dynamic control calculations made instantly by an electronic computer incorporating various operation parameters of the vehicle, such as longitudinal and lateral accelerations, vehicle speed, yaw rate, steeling angle, engine operation parameters, etc.
Those various prior art behavior control devices have their particular advantageous operational features. However, it will go without saying that those advantageous operational features will be actually exhibited only when the sensors for detecting various operation parameters of the vehicle needed for the control calculations are operating normally.
In various sensors for detecting the operation parameters of the vehicle, an acceleration sensor for detecting the longitudinal or lateral acceleration of the vehicle body is one of the most important for ensuring a high quality of the vehicle stability control. Nevertheless, the acceleration sensor is constructionally very delicate, and is relatively liable to a malfunction. At present, most of the acceleration sensors for the automobile applications have such a fundamental construction that an inertial mass element movable along a linear guide is biased by a pair of springs from linearly opposite sides thereof so as to be positioned at its neutral position in the absence of any acceleration.
The acceleration sensors of such a fundamental construction will operate unchangeably over a long period, if they are subjected to accelerations acting only along the linear directions. However, in the automobile applications, the acceleration sensors are always subjected to accelerations acting in various directions, regardless whether they are used as a longitudinal acceleration sensor or a lateral acceleration sensor, such that the inertial mass element is often rubbed against the linear guide while it is shifted therealong. Therefore, the acceleration sensors often unavoidably cause a gradual or an abrupt error in their outputs due to a sticking of the inertial mass element to the linear guide. How often and how strong the inertial mass element is rubbed against the linear guide depends on the driver of the vehicle and his/her principal driving area. Therefore, it is very difficult to estimate how long the normal operation of the acceleration sensor is guaranteed.
In Japanese Patent Laid-open Publication 7-196029 (1995), there is proposed a device for judging a failure of a longitudinal acceleration sensor of a vehicle, comprising means for calculating rotation speed of a wheel based upon an output of a wheel speed sensor, means for calculating an estimated vehicle body acceleration based upon the wheel rotation speed, a longitudinal acceleration sensor for detecting longitudinal acceleration of the vehicle, means for calculating a ratio of the vehicle longitudinal acceleration detected by the longitudinal acceleration sensor to the estimated vehicle body acceleration together with an integration calculation of a first integrated value which is decreased when the ratio is within a predetermined range while it is increased when the ratio is outside of the predetermined range, and means for conducting a predetermined failsafe processing when the first integrated value is larger than a predetermined value.
However, the difficulty in judging the normal operation of the acceleration sensors of the vehicles resides in that the vehicles do not always run on a horizontal road, occasionally climbing an uphill road or descending a downslope road, these inclinations all affecting the ostensible outputs of the acceleration sensors having the above-mentioned fundamental construction.
SUMMARY OF THE INVENTION
In view of the above-mentioned difficulty in judging the normal operation of the acceleration sensors of the vehicles, it is a primary object of the present invention to provide a behavior control device of a vehicle such as an automobile, in which the normal operation of the acceleration sensor is often timely judged with the least influence of up and down sloping of the road.
According to the present invention, the above-mentioned primary object of the present invention is accomplished by a behavior control device of a vehicle having a vehicle body, wheels supporting the vehicle body, an engine for driving the vehicle through at least a pair of drive wheels forming a part of the body support wheels, and a brake system for selectively braking at least a part of the body support wheels, the device comprising:
means for detecting operation parameters of the vehicle, the vehicle operation parameter detection means including an acceleration sensor for detecting longitudinal acceleration of the vehicle depending upon an inertia of a movable mass element, means for detecting rotation speed of at least one of the body support wheels, means for detecting a torque for driving the drive wheels, means for detecting longitudinal acceleration of the vehicle depending upon the wheel rotation speed detected by the wheel rotation speed detection means, and means for detecting longitudinal acceleration of the vehicle dependent upon the wheel drive torque detected by the wheel drive torque detection means,
means for judging the acceleration sensor as not operating normally according to the longitudinal acceleration detected by the acceleration sensor being different from the longitudinal acceleration detected by the wheel rotation dependent longitudinal acceleration detection means beyond a threshold value predetermined therefor, excepting at least when the longitudinal acceleration detected by the acceleration sensor is not different from the longitudinal acceleration detected by the wheel drive torque dependent longitudinal acceleration detection means beyond a threshold value predetermined therefor, and
means for controlling the brake system based upon the operation parameter or parameters of the vehicle detected by at least one, including the acceleration sensor, of the vehicle operation parameter detection means, so as to control a running behavior of the vehicle, with a modification thereof for a compensation for a failure of a normal operation of the acceleration sensor when it is not judged as normally operating by the acceleration sensor normal operation judgment means.
The above-mentioned modification of the running behavior control may include a suspension of the control.
When a vehicle is climbing an uphill road of an angle &agr; of inclination, the longitudinal acceleration detected by the acceleration sensor of the above-mentioned common construction will be larger than the linear acceleration of the vehicle along the road surface as much as a difference g·sin &agr;, wherein g is the acceleration of gravity, while the wheel drive torque required for accelerating the vehicle along the uphill road of the inclination angle &agr; is larger than the drive torque required for accelerating the vehicle to the same acceleration along a horizontal road as much as an amount corresponding to an acceleration g·sin &agr; of the vehicle. Therefore, if the longitudinal acceleration detected by the acceleration sensor is compared with the longitudinal acceleration detected by the wheel drive torque dependent longitudinal acceleration detection means, the two longitudinal acceleration values should be the same even when the vehicle is accelerated on an uphill road, provided that the acceleration sensor is operating normally, although the threshold val
Kramer Devon
Oberleitner Robert J.
Oliff & Berridge PLC.
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Behavior control device of vehicle checking occasionally... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Behavior control device of vehicle checking occasionally..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Behavior control device of vehicle checking occasionally... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2610230