Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-04-05
2001-04-17
Cuchlinski, Jr., William A (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S078000, C701S083000, C701S041000, C303S140000, C303S146000, C303S147000, C303S148000
Reexamination Certificate
active
06219610
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle turn control system which is arranged to generate a turn moment by controlling a brake fluid pressure applied to a brake cylinder of each wheel on the basis of vehicle turn information such as yaw rate and sideslip angle or sideslip speed, and a vehicle turn target value calculated based on a vehicle model.
A variety of vehicle turn control systems have been proposed. A typical vehicle turn control system is arranged to calculate a target value of a vehicle turn variable such as a yaw rate, a sideslip angle or sideslip speed on the basis of a vehicle model and to detect an actual value of the vehicle turn variable generated at the vehicle, and to control a braking force of each wheel so as to adjust the actual vehicle behavior variable to the target value. When the vehicle is put in an excessive oversteer or understeer state that is a turning state out of a tire gripping range, such a conventional vehicle turn control system enables the vehicle turning state to return to the tire gripping range by generating a returning spin moment at the vehicle through the brake control. Further, another vehicle turn control system is arranged to previously apply a pre-charge of pressure to a wheel cylinder to be intensified in order to improve a responsibility as to the generation of braking force of a wheel cylinder to be intensified in pressure from zero pressure.
SUMMARY OF THE INVENTION
In case of this another vehicle turn control system, each wheel cylinder of each wheel is connected to one of two lines of a master cylinder which lines are constituted by a diagonal split brake system or vertical split brake system. A typical fluid pressure circuit of the conventional vehicle turn control system comprises a master cylinder ON/OFF valve for ON/OFF controlling the discharge pressure of a master cylinder and an intensifying pump ON/OFF valve for ON/OFF controlling a discharge pressure of an intensifying pump. An intensifying control valve is disposed between each of two brake cylinders and a brake fluid pressure source constituted by the intensifying pump or the master cylinder and ON/OFF controls the fluid connection therebetween. A reducing control valve is disposed between each brake cylinder and a suction side of a reducing pump.
The discharge side of the reducing pump is connected to the brake fluid pressure source. With this arrangement, in case that a pressure In one of the two brake cylinders of one line is intensified, the intensifying pump is driven, the master cylinder ON/OFF valve is closed, and the intensifying pump ON/OFF valve is opened. Under this setting of the system, the intensifying control valve is opened while keeping the closed state of the reducing control valve. In case that a pressure of one of the brake cylinders is reduced, the reducing pump is driven and the reducing control valve is opened while keeping the closed state of the intensifying control valve. By this operation, the brake fluid is discharged from the brake cylinder to a reservoir. When a depression of the brake pedal is canceled during the anti-skid control wherein the intensifying control valve is closed, the brake fluid in each brake cylinder is quickly returned to the master cylinder through a check valve Installed parallel with the intensifying control valve.
However, in case that the pressures of the two brake cylinders connected to a line having one brake fluid pressure source have large pressure differences therebetween, if the low pressure side brake cylinder is intensified, the brake fluid in the high pressure side brake cylinder flows out through the check valve toward the discharge side of the intensifying pump to lower the brake fluid pressure of the high pressure side brake cylinder. More specifically, in order to suppress the lowering of the responsibility, if a responsibility improving pre-charge control is executed by supplying a small amount of brake fluid which is as small as an amount which does not generate braking force is executed to improve the responsibility of the brake fluid pressure control, the brake fluid flows to the brake cylinder to be pre-charged, due to the large pressure difference between the high pressure side and the low pressure side brake cylinders. As a result, the intensified gradient of the high pressure side pressure is further lowered and therefore it becomes difficult to ensure the necessary brake fluid pressure.
It is an object of the present invention to provide an improved vehicle turn control system which ensures the intensifying gradient of the brake fluid pressure of a high pressure side brake cylinder and a responsibility of a brake pressure control by suppressing the pressure intensifying of the low pressure side brake cylinder when there is a large pressure difference between the brake fluid pressures of the two brake cylinders connected to one pressure source and when it is necessary to further intensify the brake pressure in the high pressure side brake cylinder.
A turn control system according to the present invention is for a vehicle and comprises a steer angle sensor, a vehicle speed detector, a vehicle turn variable detecting section, a brake system and a controller. The steer angle sensor senses a steer angle of a wheel of the vehicle. The vehicle speed detector senses a vehicle speed. The vehicle turn variable detecting section detects a vehicle turn variable indicative of a turning state of the vehicle. The brake system applies brake fluid pressure to a brake cylinder of each wheel of the vehicle. The controller is to calculate a target vehicle turn variable on the basis of the steer angle and the vehicle speed, to control the brake system according to a difference between the actual vehicle turn variable and the target vehicle turn variable, to apply a pre-charge pressure to a brake cylinder to next receive the brake fluid pressure on the basis of the vehicle turn state when the brake system is operating, and to restrict the operation of applying the pre-charge pressure according to the vehicle turn condition.
REFERENCES:
patent: 5788342 (1998-08-01), Noguchi
patent: 5797663 (1998-08-01), Kawaguchi
patent: 5816669 (1998-10-01), Hiwatashi et al.
patent: 5-24528 (1993-02-01), None
patent: 7-329759 (1995-12-01), None
patent: 8-150920 (1996-06-01), None
patent: 8-244587 (1996-09-01), None
patent: 10-29819 (1998-02-01), None
Masato Abe, “Vehicle Dynamics and Control”, (First edition 1992). No month.
Cuchlinski, Jr. William A
Foley & Lardner
Mancho Ronnie
Nissan Motor Co,. Ltd.
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