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US 7,244,002 B2Granted
Vehicle brake system
AssigneeNissan Motor Co., Ltd.
InventorHiroshi Tsunehara
Life of this patent
Estimating the term…
Abstract
A brake-by-wire type vehicle brake system is arranged to return a piston of a master cylinder to a normal position by opening a shutoff valve so as to supply a hydraulic pressure of a pump to the master cylinder when the shutoff valve is closed and a stroke simulator is put in shutoff state and to close the shutoff valve when the stroke simulator is put in communicating state by returning the pistons of the master cylinder to the normal position.
Claims16
A vehicle brake system comprising:
- a first motion means having a first motion element which moves according to a driver's brake manipulation, the first motion means outputting a brake hydraulic pressure according to a depressing force of the first motion element;
- a wheel brake unit through which a braking force is generated at wheels;
- a brake hydraulic pressure output circuit connecting the first motion means and the wheel brake unit;
- a shutoff valve disposed in the brake hydraulic circuit, the shutoff valve shutting off a fluid communication between the first motion means and the wheel brake unit;
- a hydraulic source different from the first motion means, the hydraulic source being connected to the brake hydraulic pressure output circuit between the shutoff valve and the wheel brake unit;
- a hydraulic pressure controlling means for producing a unit hydraulic pressure in the brake hydraulic pressure output circuit between the shutoff valve and the wheel brake unit by controlling a hydraulic pressure of the hydraulic source different from the first motion means according to the brake hydraulic pressure of the first motion means when the shutoff valve is closed;
- a stroke simulator being shut off from the first motion means when the first motion element moves from a normal position, the stroke simulator being communicated with the first motion means so as to generate a stroke of the driver's brake manipulation when the shutoff valve is closed and the first motion element is positioned at the normal position;
- a stroke simulator shutoff/communication detecting means detecting whether the stroke simulator is in shutoff state or communicating state when the shutoff valve is closed;
- and
- a stroke-simulator state controlling means returning the first motion element to the normal position using the hydraulic pressure of the hydraulic source by temporally opening the shutoff valve when the shutoff valve is closed and the stroke simulator is put in shutoff state, the stroke-simulator state controlling means closing the shutoff valve when the stroke simulator is put in communicating state due to the returning of the first motion element to the normal position.
7 more elements
A vehicle brake system comprising:
- a master cylinder comprising a piston depressed according to a driver's brake manipulation, the master cylinder outputting a brake hydraulic pressure according to a depression force of the piston;
- a wheel brake unit through which braking force is generated at wheels according to the brake hydraulic pressure;
- a brake hydraulic pressure output circuit connecting the master cylinder and the wheel brake unit;
- a shutoff valve disposed in the brake hydraulic pressure output circuit, the shutoff valve shutting off a fluid communication between the master cylinder and the wheel brake unit;
- a pump connected to the brake hydraulic pressure output circuit between the shutoff valve and the wheel brake unit;
- a stroke simulator connected to the master cylinder, the stroke simulator generating a stroke of the driver's brake manipulation when the shutoff valve is closed and the piston of the master cylinder is positioned at a normal position;
- and
- a control unit connected to the shutoff valve and the pump, the control unit being arranged:
- to detect whether the stroke simulator is put in a communicating state or a shutoff state relative to the master cylinder when the shutoff valve is closed,
- to open the shutoff valve so as to return the piston of the master cylinder to the normal position by supplying a hydraulic pressure of the pump to the master cylinder when the shutoff valve is closed and the stroke simulator is put in the shutoff state, and
- to close the shutoff valve when the stroke simulator is put in the communicating state by returning the piston of the master cylinder to the normal position.
8 more elements
A method of controlling a brake-by-wire type brake system which comprises a master cylinder having a piston depressed according to a driver's brake manipulation, a wheel brake unit through which braking force is generated at wheels according to a brake hydraulic pressure, a brake hydraulic pressure output circuit connecting the master cylinder and the wheel brake unit, a shutoff valve disposed in the brake hydraulic pressure output circuit and shutting off a fluid communication between the master cylinder and the wheel brake unit, a pump connected to the brake hydraulic pressure output circuit between the shutoff valve and the wheel brake unit and a stroke simulator connected to the master cylinder so as to generate a stroke of the driver's brake manipulation when the shutoff valve is closed and the piston of the master cylinder is positioned at a normal position, the method comprising:
- detecting whether the stroke simulator is put in a communicating state or a shutoff state relative to the master cylinder when the shutoff valve is closed,
- returning the piston of the master cylinder to the normal position by opening the shutoff valve so as to supply a hydraulic pressure of the pump to the master cylinder when the shutoff valve is closed and the stroke simulator is put in the shutoff state;
- and
- closing the shutoff valve when the stroke simulator is put in the communicating state by returning the piston of the master cylinder to the normal position.
1 more element
A vehicle brake system comprising:
- a tandem master cylinder having a primary piston which strokes according to a driver's brake manipulation and a secondary piston which strokes according to the driver's brake manipulation through the primary piston;
- first and second brake hydraulic pressure output circuits through which a hydraulic pressure generated by the tandem master cylinder is supplied to first and second wheel brake units, respectively;
- first and second shutoff valves disposed in the first and second brake hydraulic pressure output circuits, respectively, the first and second shutoff valves being capable of shutting off communications between the tandem master cylinder and the first and second wheel brake units, respectively;
- a pump connected to the first brake hydraulic pressure output circuit between the first shutoff valve and the first wheel brake unit and the second brake hydraulic pressure output circuit between the second shutoff valve and the second wheel brake unit;
- a stroke simulator shut off from the tandem master cylinder when the secondary piston moves from a normal position, the stroke simulator being communicated with the tandem master cylinder so as to generate a stroke of the driver's brake manipulation when the first and second shutoff valves are closed and the secondary piston is positioned at the normal position;
- and
- a control unit connected to the first and second shutoff valves and the pump, the control unit being arranged:
- to produce a first unit hydraulic pressure at the first brake hydraulic pressure output circuit between the first shutoff valve and the first wheel brake unit and a second unit hydraulic pressure at the second brake hydraulic pressure output circuit between the second shutoff valve and the second wheel brake unit by controlling a hydraulic pressure of the pump on the basis of a hydraulic pressure detection value of the tandem master cylinder when the first and second shutoff valves are closed,
- to detect whether the stroke simulator is in a shutoff state or a communicating state when both of the first and second shutoff valves are closed,
- to supply the hydraulic pressure of the tandem master cylinder to the first brake hydraulic pressure output circuit by opening the first shutoff valve when both of the first and second shutoff valves are closed and the stroke simulator is put in the shutoff state, and
- to supply the hydraulic pressure of the pump to the second brake hydraulic pressure output circuit by closing the second shutoff valve when the stroke simulator is put in the shutoff state.
8 more elements
Dependencies are inferred from the claim text.