Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Reexamination Certificate
1999-12-08
2001-08-28
Oberleitner, R. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
C303S146000, C303S140000
Reexamination Certificate
active
06280003
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to braking force distribution control systems used on a motor vehicle. More specifically, the invention relates to such systems and their method of operation wherein the system comprises a wheel speed sensor and brake activation is controlled using information from wheel speed sensors.
BACKGROUND OF THE INVENTION
Traditional braking force distribution control starts its control on two rear wheels based on the same vehicle deceleration threshold value. However, while the vehicle is turning or the vehicle load shifts in the transverse direction, the traditional control method does not provide appropriate braking force distribution control to compensate for such load shifting. This invention provides initial braking force distribution control correctly compensating for vehicle load shifts.
SUMMARY OF THE INVENTION
A vehicle brake hydraulic device system is disclosed which is comprised of a hydraulic unit having a wheel speed sensor to detect a wheel speed, a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, and an auxiliary hydraulic circuit connected from said wheel cylinder to an auxiliary reservoir via an outlet valve and an electronic control device to control the hydraulic unit. The system operates by (1) independently determining the speed of both rear wheels and (2) determining whether a rear wheel subject to control is an inner or outer wheel when the car is in a turn. Information of the speed of each of the rear wheels is sent to a microprocessor and calculations are carried out to determine if braking force distribution control should be applied and if so on which rear wheel.
If the outer wheel is to be controlled, the deceleration threshold value is increased according to the amount of acceleration in a lateral direction. If the absolute value of vehicle deceleration exceeds the deceleration threshold value, the braking distribution control is operated on the rear wheel. If the inner wheel is to be controlled, deceleration threshold value is decreased according to said acceleration in the lateral direction. Furthermore, if the absolute value of vehicle deceleration exceeds said deceleration threshold value, braking distribution control is operated on the rear wheel. Although it is not necessary, the system preferably includes a sensor for measuring G forces. The sensor can measure G forces when the vehicle accelerates forward or decelerates in braking. Further, the sensor measures lateral acceleration and all the sensor information is sent to the microprocessor. The determination of which wheel to activate braking force distribution control can be based solely on wheel speed sensors, solely on one or more G force sensors or a combination of data from both wheel speed sensors and G force sensors. The system provides an improved method of braking force distribution control.
In a normal braking force distribution control, one whole process of control must be conducted on each rear wheel. For example, one group of processing is first conducted on a right rear wheel, then another group on a left rear wheel. Here, provided that the right rear wheel is processed first, the system determines whether the right rear wheel is located at an inner side of the curve or an outer wide of the curve. If the right rear wheel is located at the outer side, then a threshold deceleration value is increased based on the lateral acceleration which is determined by a G sensor or other information. If the right rear wheel is located at the inner side, then the threshold deceleration value is decreased based on the lateral acceleration. After this, the left rear wheel is processed in the same matter.
The invention may comprise a vehicle brake hydraulic device comprising a hydraulic unit having a wheel speed sensor to detect a wheel speed, a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, and an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve and an electronic control device to control the hydraulic unit. The device of the invention determines whether a rear wheel subject to control is an inner or outer wheel. If the outer wheel is to be controlled, deceleration threshold value is increased according to an acceleration in the lateral direction. If the absolute value of vehicle deceleration exceeds the deceleration threshold value; a slip threshold value is increased according to the difference between an inner wheel speed and an outer wheel speed. Further, when the rear wheel slip ratio exceeds the slip threshold value, the braking distribution control is operated on the rear wheel. If the inner wheel is to be controlled, the deceleration threshold value is decreased according to the acceleration in the lateral direction. If the absolute value of vehicle deceleration exceeds the deceleration threshold value; the slip threshold value is decreased based on the difference between an inner wheel speed and an outer wheel speed. When the rear wheel slip ratio exceeds the slip threshold value, the braking distribution control is operated on the rear wheel.
Another embodiment of the invention provides a method of braking force distribution control for a vehicle brake hydraulic device. The device comprises a hydraulic unit having a wheel speed sensor to detect a wheel speed; a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve, means for detecting acceleration of a vehicle movement, and an electronic control device to control the hydraulic unit. The device independently determines the speeds of rear wheels of the vehicle, and determines whether to apply braking force distribution to an inner rear wheel or an outer rear wheel. If the rear wheel subject to control stands an outer rear wheel application of braking force distribution control is effected to the outer rear wheel when a deceleration threshold value is increased according to acceleration of a vehicle lateral direction and the absolute value of vehicle deceleration exceeds the deceleration threshold value. If the rear wheel subject to control stands an inner rear wheel, application of braking force distribution control is effected to the inner wheel when a deceleration threshold value is increased according to lateral acceleration acting on the vehicle and the absolute value of vehicle deceleration exceeds the deceleration threshold value.
In yet another embodiment the invention provides a method of braking force distribution control for a vehicle brake hydraulic system. The system is comprised of a hydraulic unit having a wheel speed sensor to detect a wheel speed; a main hydraulic circuit connected from a master cylinder to a wheel cylinder via an inlet valve, an auxiliary hydraulic circuit connected from the wheel cylinder to an auxiliary reservoir via an outlet valve, means for detecting acceleration of a vehicle movement, and an electronic control device to control the hydraulic unit. The system determines the wheel speed of at least two rear wheels and determines whether to apply braking force distribution control to an inner rear wheel or an outer rear wheel. If the rear wheel subject to control stands an outer rear wheel, application of braking force distribution control is effected to the outer rear wheel when a deceleration threshold value is increased according to acceleration of a vehicle lateral direction, and the absolute value of vehicle deceleration exceeds the deceleration threshold value. Then a slip threshold value is increased according to a difference between the inner wheel speed and the outer wheel speed, and the rear wheel slip ratio exceeds the slip threshold value.
If the rear wheel subject to control stands an inner rear wheel, application of braking force distribution control is effected to the outer rear wheel when a deceleration threshold value is decreased a
Nishizawa Hiromitsu
Oshiro Hiroshi
Taguchi Makoto
Bozicevic Field & Francis LLP
Cannon Alan W.
Kramer Devon
Nisshinbo Industries Inc.
Oberleitner R.
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