Brake Apparatus

A brake apparatus comprising:

• an oil passage connecting a master cylinder and a wheel cylinder therebetween;
• a valve configured to switch a communication state of the oil passage;
• a by-wire control unit configured to close the valve to increase a pressure in the wheel cylinder by a hydraulic source provided separately from the master cylinder, according to a state of a brake operation performed by a driver;
• a pressing force brake unit configured to open the valve to increase the pressure in the wheel cylinder by the master cylinder;
• and
• a stroke simulator connected to a portion of the oil passage between the master cylinder and the valve, and configured to generate a brake operation reaction force due to an increase and a reduction in a volume of a positive pressure chamber formed inside the stroke simulator,
• wherein brake fluid contained in a first chamber of the master cylinder flows into the positive pressure chamber at the time of control by the by-wire control unit, and
• wherein a fluid amount that can be supplied from the first chamber is larger than a fluid amount that a positive pressure chamber can absorb therein.

A brake apparatus comprising:

• an oil passage connecting a master cylinder and a wheel cylinder therebetween;
• a valve configured to switch a communication state of the oil passage;
• a by-wire control unit configured to close the valve to increase a pressure in the wheel cylinder by a hydraulic source provided separately from the master cylinder according to a state of a brake operation performed by a driver;
• a pressing force brake unit configured to open the valve to increase the pressure in the wheel cylinder by the master cylinder;
• and
• a stroke simulator connected to a portion of the oil passage between a first chamber of the master cylinder and the valve and including a piston therein, the stroke simulator being configured to generate a brake operation reaction force due to an increase and a reduction in a volume of a positive pressure chamber according to activation of the piston in an axial direction,
• wherein a brake fluid amount that can flow out from the first chamber at the time of control by the by-wire control unit is set to a larger amount than a brake fluid amount flowing into the positive pressure chamber until the piston is maximally stroked.

A brake apparatus comprising:

• a master cylinder including a first chamber connected to a first pipe system;
• a stroke simulator provided in a branch oil passage branching off from an oil passage connecting the first chamber and a wheel cylinder therebetween, and configured in such a manner that a piston dividing an inside of the stroke simulator is activated and a volume of a positive pressure chamber inside the stroke simulator is increased or reduced due to an inflow of brake fluid thereto;
• a by-wire control unit configured to close a valve provided in the oil passage to increase a pressure in the wheel cylinder by a pump provided separately from the master cylinder according to a state of a brake operation performed by a driver;
• and
• a pressing force brake unit configured to open the valve to increase the pressure in the wheel cylinder by the master cylinder,
• wherein a brake fluid amount in the first chamber when the master cylinder is deactivated is larger than a brake fluid amount in the positive pressure chamber when the piston is maximally stroked.