Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1998-10-06
2001-02-06
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
Reexamination Certificate
active
06183048
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention related to a brake system of automobile, and more particularly, to a brake control device for more effectively actuating the brake system of an automobile in braking a backward moving of the automobile.
2. Description of the Prior Art
In Japanese Patent Laid-open Publication 7-165041 it is proposed to control the distribution of the braking force between the front wheels and the rear wheels of an automobile, particularly a heavy track or the like in which a large mass of the vehicle body is centered at a relatively high position above the road surface, with the wheel base being relatively short, so that when the automobile is sharply braked in a forward running, the rear wheels lose much of the ground contact load, thereby correspondingly losing the tire grip for effecting the braking, while the rear wheels are substantially locked and slide over the road surface. According to the proposal, the supply of the brake fluid to the rear wheels is regulated by a regulator valve actuated in response to an imbalance of the suspension fluid pressures of the front and rear wheels which reflects thereon how the ground contact load of the wheels has shifted from the rear wheels to the front wheels, such that the supply of the brake fluid to the rear wheels is throttled by the regulator valve according to an increase in the imbalance of the suspension fluid pressures of the front and rear wheels. In this connection, it is also proposed not to actuate the regulator valve when the automobile is braked while climbing a relatively steep slope or when the automobile is braked when it is moving backward, so that normal full braking is available at the rear wheels.
In the above-mentioned prior art, the braking force available at the rear wheels is the normally available maximum braking force also available at the front wheels.
SUMMARY OF THE INVENTION
The present invention increases the braking force available at the rear wheels beyond the normally available maximum level in response to a depression of the brake pedal by a driver when the automobile is to be sharply braked in a backward movement, with the ground contact load being shifted from the front wheels to the rear wheels.
Therefore, it is a primary object of the present invention to provide a brake control device of an automobile having a brake system, the brake control device controlling the brake system to apply a larger braking force to the rear wheels than to the front wheels when desired according to a depression of a brake pedal by a driver.
According to the present invention, the above-mentioned primary object is accomplished by a brake control device of an automobile having a pair of front wheels and a pair of rear wheels, and a brake system for selectively braking each of the pairs of front and rear wheels, the brake control device comprising means for detecting a backward movement of the automobile, means for detecting a predetermined locking condition of at least one of the pair of front wheels, and means for controlling the brake system such that braking force applied by the brake system to the pair of rear wheels is stronger than braking force applied by the brake system to the pair of front wheels when the automobile is moving backward with at least one of the pair of front wheels locked more than the predetermined locking condition.
By the brake control device of the above-mentioned concept being incorporated into an automobile, the automobile can be braked more sharply and quickly in a backward movement than the conventional braking in a backward movement of the automobile, so that a bumping at a wall by the rear of the automobile or a lane off of a rear wheel or wheels is effectively avoided.
In the brake control device of the present invention, the brake system control means may control the brake system such that the braking force applied by the brake system to the pair of rear wheels is stronger than the braking force applied by the brake system to the pair of front wheels when the automobile is moving backward with at least one of the pair of front wheels being locked at a more locking condition than the predetermined locking condition, while the pair of rear wheels are braked at a larger braking force than a predetermined threshold braking force.
By such an arrangement, the application of the brake control device according to the present invention is focussed to an operating condition of the automobiles where desired.
A brake system such as selectively braking each of the pairs of front and rear wheels of an automobile is available when the automobile is equipped with a behavior control system such as shown in, for example, U.S. Pat. No. 5,702,165 about “Behavior Control System of Vehicle Distinctive of Oversteered and Understeered Conditions” or U.S. Ser. No. 08/723,757 about “Stability Control Device of Vehicle Operative Against Spin and Drift-out in Harmony”, both having been assigned to the same assignee as the present application. The brake system for selectively braking each of the pairs of front and rear wheels of those behavior control is of course not operated when the automobile is moved backward generally at a very low speed. Therefore, such a brake system for a behavior control is fully available for the brake control for a backward movement of an automobile according to the present invention.
Therefore, it is a further object of the present invention to effectively realize the above-mentioned basic control concept by utilizing the brake system of a behavior control of an automobile.
In order to accomplish the above-mentioned further object of the present invention, the brake control device according to the present invention may be constructed such that the brake system comprises wheel cylinders each applying a braking force to each corresponding one of the pairs of front and rear wheels according to a supply of a pressurized brake fluid thereto, a brake pedal, a master cylinder for pressurizing the brake fluid to supply the pressurized brake fluid to the wheel cylinders of the pair of front wheels according to a depression of the brake pedal by a driver, a powered pressurized brake fluid source means, a hydro-booster for generating a pressurized flow of the brake fluid from the powered pressurized brake fluid source means according to the pressurization of the brake fluid by the master cylinder to supply the pressurized flow of the brake fluid to the wheel cylinders of the pair of rear wheels, a pair of inlet control valves each selectively opening through or interrupting an inlet passage of each of the wheel cylinders of the pair of rear wheels, a pair of outlet control valves each selectively interrupting or opening through an outlet passage of each of the wheel cylinders of the pair of rear wheels, and a pair of changeover valves for selectively exchanging a connection of each of the wheel cylinders of the pair of rear wheels with the hydro-booster and a connection thereof with the powered pressurized brake fluid source means via each corresponding one of the pair of inlet control valves with one another the brake system control means including means for controlling the pair of changeover valves, the pair of inlet control valves and the pair of outlet control valves such that the changeover valve connects each of the wheel cylinders of the pair of rear wheels with the powered pressurized brake fluid source means via each corresponding one of the pair of inlet control valves, while the pair of inlet control valves and the pair of outlet control valves are selectively opened or closed so as to apply larger braking forces to the pair of rear wheels than braking force applied to the pair of front wheels by a depression of the brake pedal by the driver, when the automobile is moving backward with at least one of the pair of front wheels being locked at a more locking condition than the predetermined locking condition, while the pair of rear wheels are braked at a larger braking force than a predetermined threshold braking force.
Hosomi Kazushi
Takahira Yosuke
Bartz C. T.
Oliff & Berridg,e PLC
Schwartz Christopher P.
Toyota Jidosha & Kabushiki Kaisha
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