Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Reexamination Certificate
1999-05-25
2001-07-31
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
C303S186000
Reexamination Certificate
active
06267454
ABSTRACT:
This Application claims the benefit of Japanese Application No. Hei 10-143790 filed on May 26, 1998, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brake system, and more particularly, to a method of controlling a brake force in a brake system including a front wheel system and a rear wheel system.
2. Description of the Related Art
An example of an electrically operated brake used for a vehicle is disclosed in Japanese Unexamined Patent Publication No. 3-41233 (corresponding to U. S. Pat. No. 5,107,967). This electrically operated brake operates as described below. In order to generate the required brake force, torque of an electric motor is transmitted to a brake friction pad via a worm mechanism for converting a rotary motion into a linear motion. As a result, the brake force is applied to the vehicle. At this time, the brake force is controlled in such a manner that a rotary angle of the electric motor is detected by an encoder and the position of the brake friction pad is controlled according to the rotary angle.
In another example of an electrically operated brake used for a vehicle, instead of the rotary angle of the electric motor, the pushing force of the brake friction pad is detected by a sensor. The brake force is then controlled by the detected pushing force.
However, the above braking devices have the following problems. The encoder for detecting a rotary angle of the motor and the brake friction pad pushing force sensor for detecting a pushing force of the brake friction pad are arranged in each braking device of the front and the rear wheels. In other words, the encoder and the brake friction pad pushing force sensor must be arranged in each of the four braking devices of a vehicle. This allows the brake force of each braking device to be controlled by an electronic control unit according to an output signal sent from each encoder and sensor. Since each sensor must be arranged in a brake caliper, the sensor has to be able to resist rough conditions such as high temperatures and intense vibrations. As a result, the cost of the sensor is raised. It is difficult to reduce the overall cost of the braking device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method of controlling brake force in a brake system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method of controlling brake force which results a brake system with a reduced overall cost.
Another object of the present invention is to provide a method of controlling brake force which requires a sensor to be installed only in the front wheel system and not in the rear wheel system.
A further object of the present invention is to provide a method of controlling brake force in a brake system including a front wheel system and a rear wheel system, and a wheel speed of one system is used as a target speed and a wheel speed of the other system is controlled by a feedback mechanism based on the target speed.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and the claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the present invention provides a method of controlling the brake force in a brake system including a front wheel system and a rear wheel system. In the front wheel brake system, the brake force is generated and controlled by utilizing information sent from a brake friction pad pushing force sensor corresponding to the operation force given to a brake pedal. In the rear wheel brake system, a feedback control is conducted so that a wheel speed of the rear wheel can follow a wheel speed of the front wheel. Accordingly, it is unnecessary to provide a brake friction pad pushing force sensor in the rear wheel system of the brake system. Therefore, it is possible to reduce the cost of the overall braking system.
In another aspect, in the present invention, a method of controlling brake force in a brake system composed of two systems of a front wheel system and a rear wheel system, includes the steps of: operating a brake by hydraulic pressure corresponding to an amount of brake operation in the front wheel system when the brake is applied; and conducting feedback control so that a wheel speed of the rear wheel system can be fed back aiming at a wheel speed of the front wheel system.
In a further aspect, in the present invention, a method of controlling brake force in a brake system composed of two systems of a front wheel system and a rear wheel system, includes the steps of: setting a target hydraulic pressure P
o
corresponding to an amount of application of a brake pedal in the front wheel system when the brake is applied; finding actual hydraulic pressure P
w
of the brake of the front wheel; finding a difference (&Dgr;P=P
o
−P
w
) between target hydraulic pressure P
o
and actual hydraulic pressure P
w
of the brake; controlling the brake force of the front wheel so that the difference can be zero; taking in actual wheel speed V
wf
of the front wheel and actual wheel speed V
wr
of the rear wheel; and controlling the brake force of the rear wheel so that a difference (&Dgr;Vw=V
wf
−V
wr
) between the actual wheel speed of the front wheel and the actual wheel speed of the rear wheel can be zero.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4623044 (1986-11-01), Ohta et al.
patent: 5107967 (1992-04-01), Fujita et al.
patent: 5163743 (1992-11-01), Leppek et al.
patent: 5234262 (1993-08-01), Walenty et al.
patent: 5401082 (1995-03-01), Fuchs et al.
patent: 5574644 (1996-11-01), Butsuen et al.
patent: 5646849 (1997-07-01), Walenty et al.
patent: 5855419 (1999-01-01), Urai et al.
patent: 6017101 (2000-01-01), Matsuda
patent: 3-41233 (1991-02-01), None
Akebono Brake Inudstry Co., Ltd.
Morgan & Lewis & Bockius, LLP
Oberleitner Robert J.
Sy Mariano
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