A brake control device includes a brake operation member, a pressurization unit, a master cylinder unit, a connection path connecting a separation chamber and a reaction force chamber, an electromagnetic valve at the connection path, and a control device. The control device includes a specified control section configured to, when the brake operation member is operated in a closed state of the electromagnetic valve, execute activation-time control in which the pressurization unit supplies fluid to a servo chamber based on a predetermined pattern, a determination section configured to determine whether a pressure difference between pressure in the reaction force chamber and pressure in the separation chamber, is equal to or less than a threshold value, and a valve control section configured to open the electromagnetic valve when the determination section determines the pressure difference is equal to or less than the threshold value after start of the activation-time control.

A master cylinder device includes a reservoir tank, a master cylinder, a piston, and a pair of cup seals. The master cylinder includes a cylinder body having a cylinder chamber and a master port. The piston is inserted into the cylinder chamber, and has a relief port that communicates with the master port. The cup seals are provided on an inner circumference of the cylinder chamber, being positioned in front and rear of the master port, and seals a space between the inner circumference of the cylinder chamber and an outer circumference of the piston. The relief port is closed by the front cup seal, as the piston moves forward, to generate brake fluid pressure in a brake fluid in a hydraulic chamber. The relief port is tilted from a front side to a rear side, from the outer circumference toward an inner circumference of the piston.

A master cylinder device includes a reservoir tank, a master cylinder, a piston, and a pair of cup seals. The master cylinder includes a cylinder body having a cylinder chamber and a master port. The piston is inserted into the cylinder chamber, and has a relief port that communicates with the master port. The cup seals are provided on an inner circumference of the cylinder chamber, being positioned in front and rear of the master port, and seals a space between the inner circumference of the cylinder chamber and an outer circumference of the piston. The relief port is closed by the front cup seal, as the piston moves forward, to generate brake fluid pressure in a brake fluid in a hydraulic chamber. The relief port is tilted from a front side to a rear side, from the outer circumference toward an inner circumference of the piston.

A hydraulic brake assembly (12) includes a housing (24) having first and second side-by-side bores (30), each defining a respective master cylinder assembly. Each master cylinder assembly includes a master cylinder piston (32) slidably movable by actuation of a respective brake pedal (18a, 18b) to and between an active position and an inactive position. A spool (74) slidably disposed within a piston bore (70) of the master cylinder piston (32) is operable in a first mode to direct hydraulic fluid from a quick-fill chamber (62) to a master cylinder chamber (50) at a first pressure upon initial movement of the master cylinder piston (32) from the inactive position toward the active position. The spool (74) is operable in a second mode to direct hydraulic fluid from the quick-fill chamber (62) to a tank (20) when pressure in the master cylinder chamber (50) reaches a predefined threshold.

A hydraulic brake assembly (12) includes a housing (24) having first and second side-by-side bores (30), each defining a respective master cylinder assembly. Each master cylinder assembly includes a master cylinder piston (32) slidably movable by actuation of a respective brake pedal (18a, 18b) to and between an active position and an inactive position. A spool (74) slidably disposed within a piston bore (70) of the master cylinder piston (32) is operable in a first mode to direct hydraulic fluid from a quick-fill chamber (62) to a master cylinder chamber (50) at a first pressure upon initial movement of the master cylinder piston (32) from the inactive position toward the active position. The spool (74) is operable in a second mode to direct hydraulic fluid from the quick-fill chamber (62) to a tank (20) when pressure in the master cylinder chamber (50) reaches a predefined threshold.

A vehicle braking system includes a master cylinder having a pedal feel simulator incorporated therein, a reservoir configured to retain a volume of unpressurized brake fluid for use in the vehicle braking system, a wheel cylinder coupled to the master cylinder via a first braking circuit, an electronically-controlled pressure generating unit configured to move fluid through the first braking circuit to the wheel cylinder in a first mode of operation, and a two-way valve positioned in the first braking circuit and configured to selectively decouple the master cylinder from the wheel cylinder. In the first mode of operation, the master cylinder is decoupled from the wheel cylinder via the two-way valve and the master cylinder is coupled to the reservoir via the two-way valve. In a second mode of operation, the master cylinder is coupled to the wheel cylinder via the two-way valve.

A vehicle braking system includes a master cylinder having a pedal feel simulator incorporated therein, a reservoir configured to retain a volume of unpressurized brake fluid for use in the vehicle braking system, a wheel cylinder coupled to the master cylinder via a first braking circuit, an electronically-controlled pressure generating unit configured to move fluid through the first braking circuit to the wheel cylinder in a first mode of operation, and a two-way valve positioned in the first braking circuit and configured to selectively decouple the master cylinder from the wheel cylinder. In the first mode of operation, the master cylinder is decoupled from the wheel cylinder via the two-way valve and the master cylinder is coupled to the reservoir via the two-way valve. In a second mode of operation, the master cylinder is coupled to the wheel cylinder via the two-way valve.

A bicycle hydraulic assembly includes a casing, a first piston, and a second piston. The casing has a hydraulic chamber, an inlet channel, and an outlet channel connected to the hydraulic chamber. The first piston is located in the hydraulic chamber. The second piston is sleeved on the first piston. The second piston has a first end portion and a second end portion opposite to each other. The first end portion is wider than the second end portion located farther away from the inlet channel than the first end portion. When the first piston is moved a distance smaller than a threshold distance, the first piston is moved relative to the second piston while the second piston is stationary relative to the casing. When the first piston is moved a distance greater than the threshold distance, the first piston forces the second piston to move relative to the casing.

A vehicle braking device provided with a hydraulic circuit having a first system, a second system, and a connection flow channel connecting both systems. The vehicle braking device includes a fluid supply unit supplying fluid to the first system, a first braking unit, for applying a braking force to a first wheel by using the fluid flowing in the first system, a second braking unit, for applying a braking force to a second wheel by using the fluid flowing in the second system, a determination unit for determining whether the fluid is leaking from the second system, and a control unit for executing specific control for controlling the fluid supply unit so that an amount of fluid supplied to the first system is increased in response to determination by the determination unit that the fluid is leaking from the second system.

A master cylinder device includes a reservoir tank, a master cylinder, a piston, and a pair of cup seals. The master cylinder includes a cylinder body having a cylinder chamber and a master port. The piston is inserted into the cylinder chamber, and has a relief port that communicates with the master port. The cup seals are provided on an inner circumference of the cylinder chamber, being positioned in front and rear of the master port, and seals a space between the inner circumference of the cylinder chamber and an outer circumference of the piston. The relief port is closed by the front cup seal, as the piston moves forward, to generate brake fluid pressure in a brake fluid in a hydraulic chamber. The relief port is tilted from a front side to a rear side, from the outer circumference toward an inner circumference of the piston.