Fluid-pressure and analogous brake systems – Speed-controlled – Odd condition or device detection
Reexamination Certificate
1998-11-05
2001-02-27
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Odd condition or device detection
C188SDIG002
Reexamination Certificate
active
06193332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brake system for use in a motor vehicle, and more particularly to a brake control system capable of maintaining a braking force even when a brake pedal is released from being stepping-on during a stop.
2. Description of the Related Art
In recent years, in order to lighten the fatigue of a driver resulting from continuous stepping on a brake pedal during waiting for traffic light or running in traffic jam, there has been developed a brake system operating during a stop (which will be referred hereinafter to as an in-stop brake system) which automatically applies the brakes during a stop.
As exemplified by Japanese Unexamined Patent Publication No. 8-48220, there has been known an in-stop brake system designed such that, when a predetermined period of time elapses after a brake pedal is stepped on while a motor vehicle is in stop, an opening and closing valve installed in a brake fluid passage defined between a master cylinder and a wheel cylinder is put in a closed condition to maintain a braking force even if the driver releases the brake pedal from stepping.
There is a problem which arises with such an in-stop brake system, however, in that problems can occur because the driver is required to wait for the predetermined period of time in a state of stepping on the brake pedal until the brake system automatically operates after a stop. In addition, since a braking force is only maintained in accordance with the stepping force by the driver, there is a possibility that the motor vehicle will start to move if the braking force maintained due to the stepping by the driver is low.
SUMMARY OF THE INVENTION
The present invention has been developed with a view to eliminating these problems, and it is therefore an object of this invention to provide an in-stop brake system which is put in further practical use and which is easy to use.
Bearing the above object in mind, according to the present invention, there is provided an in-stop brake system comprising: stop detecting means for detecting a stop condition of a motor vehicle; accelerator detecting means for detecting an operating quantity of an accelerator pedal; brake detecting means for detecting an operating quantity of a brake pedal or a braking force varying in accordance with the operating quantity of the brake pedal; valve means provided on a brake fluid passage between a wheel cylinder and a master cylinder for closing or opening thereof; and a control unit for controlling an operation of an in-stop brake and an opening and closing operation of the valve means on the basis of outputs of the stop detecting means, the accelerator detecting means and the brake detecting means. The control unit comprises; operation decision means for allowing the in-stop brake to operate when a braking force generated upon a driver stepping on the brake pedal exceeds a predetermined braking force under the conditions that the motor vehicle is in a stopped condition and that the accelerator pedal is in a released condition, the operation decision means being further operable to inhibit the in-stop brake from being operated when the accelerator pedal is stepped on; and valve drive means for closing the valve means when the operation decision means allows the operation of the in-stop brake, and further for opening the valve means when the operation decision means inhibits the operation of the in-stop brake.
In a preferred form of the invention, the in-stop brake system further comprises grade detecting means for directly or indirectly detecting an inclination between front and rear portions of the motor vehicle as a road grade. The control unit receives an output of the grade detecting means so that it changes the value of the predetermined braking force, which is one of the in-stop brake operation conditions, in accordance with the detected road grade.
In another preferred form of the invention, the in-stop brake system further comprises warming-up detecting means for directly or indirectly detecting a warming-up condition of an engine of the motor vehicle. The control unit receives an output of the warming-up detecting means so that it changes the value of the predetermined braking force, which is one of the in-stop brake operation conditions, in accordance with the detected engine warming-up condition.
In a further preferred form of the invention, the value of the predetermined braking force, which is one of the in-stop brake operation conditions, is set to a value capable of maintaining the stopping of the motor vehicle without regard to a road grade or a warming-up condition of an engine of the motor vehicle.
In a yet further preferred form of the invention, the in-stop brake system further comprises warning means for informing a motor vehicle driver of a control condition of the in-stop brake, wherein the control unit makes the warning means give a warning when a movement of the motor vehicle is detected in spite of the in-stop brake being in operation.
In a still further preferred embodiment of the invention, the warning, which is given by the warning means when a movement of the motor vehicle is detected in spite of the in-stop brake being in operation, is stopped through at least a brake operation by the driver.
In a further preferred form of the invention, the control unit releases the in-stop brake from its operating condition when the brake pedal is once released or substantially released from its operating condition after the in-stop brake has been put into operation and subsequently the brake pedal is again stepped on to generate the predetermined braking force.
In a further preferred form of the invention, the in-stop brake system further comprises a check valve coupled in parallel to the valve means for allowing only flow of a brake fluid from the master cylinder to the wheel cylinder, wherein, when the brake fluid passes through the check valve upon the driver re-stepping on the brake pedal to cause an increase in a braking force of the wheel cylinder, the control unit makes a decision that the brake pedal is once released or substantially released from its operating condition after the in-stop brake has been put into an operating condition and subsequently the brake pedal is again stepped on to generate the predetermined braking force.
In a further preferred form of the invention, the control unit makes a stop lamp go on while the in-stop brake is in operation even if the brake pedal is in a released condition.
In a further preferred form of the invention, the in-stop brake system further comprises engine detecting means for detecting whether the engine is stopped or not. The control unit receives an output of the engine detection means so that it inhibits the in-stop brake from being operated during stoppage of the engine.
In a further preferred form of the invention, the in-stop brake system further comprises a switch through which a driver is able to make a selection such that the in-stop brake is permitted or inhibited to operate.
In a further preferred form of the invention, the in-stop brake system further comprises: engine detecting means for detecting whether an engine of the motor vehicle is stopped or not; hand brake detecting means for detecting an operating condition of a hand brake; and warning means for generating a warning. The control unit receives outputs of the engine detecting means and the hand brake detecting means so that it makes the operation of the in-stop brake continue only for a predetermined period of time and the warning means to give a warning even if the engine is stopped during the time when the in-stop brake is in operation and the hand brake is out of operation.
In a further preferred form of the invention, the operations of the in-stop brake and the warning means, which are continued for the predetermined period of time even if the engine is stopped during the time when the in-stop brake is in operation and the hand brake is out of operation, are stopped at least by a driver stepping on the brake pedal or op
King Bradley
Mitsubishi Denki & Kabushiki Kaisha
Oberleitner Robert J.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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