Abstract: A vehicle brake apparatus in which a self-locked state of a cut-off valve is quickly relieved if the valve becomes stuck in the self-locked state. The vehicle brake apparatus comprises a master cylinder to have wheel cylinders generate a braking force, master cut-off valves of a normally open type, a slave cylinder electrically driven to apply a braking force to the wheel cylinders. The apparatus also includes pressure sensors for detecting brake fluid pressures generated by the master cylinder and the slave cylinder, and out-valves through which the brake fluid pressure on the wheel cylinders is reduced. If the brake fluid pressure corresponding to a depressing stroke of a brake pedal becomes higher than a valve openable pressure on the master cut-off valves while the brake pedal is being operated, the brake fluid pressure on the wheel cylinders is reduced through the out-valves.

Abstract: When an electrical fluid pressure generator fails and a wheel cylinder is operated by brake fluid pressure generated by a master cylinder, if a first fluid pressure system leading to a rear fluid chamber of the electrical fluid pressure generator fails and is opened to the atmosphere, braking is performed by brake fluid pressure of a second fluid pressure system transmitted from the master cylinder through a front fluid chamber of the electrical fluid pressure generator to a wheel cylinder. At this time, a front supply port, which communicates through a front second cup seal, does not communicate with the master cylinder but with a reservoir. Such configuration prevents leakage of the brake fluid pressure generated by the master cylinder through the front supply port, the front second cup seal and the rear fluid chamber, thereby ensuring braking by the second fluid pressure system.

Abstract: In a BBW type brake device, if a slave cylinder becomes inoperable, when a master cylinder is operated for the first time, a master cut valve is opened to charge brake fluid into a reservoir of a hydraulic modulator, and since the brake fluid charged into the reservoir is increased in pressure by driving a hydraulic pump when the master cut valve is closed, wheel cylinders are operated. Since the amount of brake fluid on the downstream side relative to the master cut valve is increased by charging the reservoir with brake fluid, it is possible to increase the pressure of the brake fluid of the reservoir by driving the hydraulic pump and generate brake fluid pressure by a hydraulic modulator that is higher than the brake fluid pressure generated by the master cylinder, thereby generating sufficient braking force without increasing the depressing force applied to a brake pedal.

Abstract: In a brake system, two first fluid pressure chambers of a master cylinder respectively communicate with two second fluid pressure chambers of a motor cylinder. The two second chambers communicate with four wheel cylinders through an ABS. The wheel cylinders are operated by brake fluid pressure generated by the master cylinder in an abnormal situation where the motor cylinder is non-operational. The brake system includes two separate independent fluid pressure lines: one line extending from one of the first chambers in the master cylinder to the wheel cylinders via one of the second chambers in the motor cylinder; and the other line extending from the other first chamber in the master cylinder to the wheel cylinders via the other second chamber in the motor cylinder. Thus, even if an abnormality occurs in one of the two fluid pressure lines, a minimum necessary braking force is secured.

Abstract: In a BBW type vehicle brake device, first and second fluid paths that are connected to each other are both connected to a slave cylinder with a simple structure equipped with a single fluid pressure chamber, thereby enabling wheel cylinders having two lines to be operated and eliminating the need for a complicated tandem type slave cylinder. When the slave cylinder becomes inoperable due to malfunction of the power supply, by opening first and second master cut valves and closing the communication control valve, braking is carried out by brake fluid pressure generated by a master cylinder. In this process, since the interconnection between the first and second fluid paths is blocked by closing the communication control valve, even if the wheel cylinder of one of the brake lines suffers from a liquid leakage malfunction, the other remained brake line is enabled to ensure a braking force.

Abstract: Systems and methods to prevent dragging of a fluid pressure type disk brake system are described herein. Brake fluid pressure generated by a master cylinder during a braking operation is transmitted to a wheel cylinder via a VSA system. The VSA system includes a low pressure accumulator and an out-valve disposed between the wheel cylinder and the low pressure accumulator. Temporarily opening the out-valve during a braking operation allows part of the brake fluid that would otherwise be supplied to the wheel cylinder to be supplied to the low pressure accumulator. After the braking operation by the driver is completed, brake fluid supplied to the wheel cylinder is returned to the master cylinder. Thus, a piston of the wheel cylinder is withdrawn by an extra amount corresponding to the amount of brake fluid supplied to the low pressure accumulator, thus reliably prevents disk pad dragging in the disk brake system.

Abstract: In an electric braking device that produces brake fluid pressure by driving a second slave piston in the axial direction with the driving force by a motor, a driving force transmission mechanism for transferring the driving force by the motor includes a nut that rotates upon reception of the rotational driving force by the motor, and a ball screw shaft which is engaged with the nut and is movable in the axial direction and which abuts the second slave piston. The electric braking device further includes a worn-out reducer for reducing the worn-out of a contact part between the ball screw shaft and the second slave piston.

Abstract: When an electrical fluid pressure generator fails and a wheel cylinder is operated by brake fluid pressure generated by a master cylinder, if a first fluid pressure system leading to a rear fluid chamber of the electrical fluid pressure generator fails and is opened to the atmosphere, braking is performed by brake fluid pressure of a second fluid pressure system transmitted from the master cylinder through a front fluid chamber of the electrical fluid pressure generator to a wheel cylinder. At this time, a front supply port, which communicates through a front second cup seal, does not communicate with the master cylinder but with a reservoir. Such configuration prevents leakage of the brake fluid pressure generated by the master cylinder through the front supply port, the front second cup seal and the rear fluid chamber, thereby ensuring braking by the second fluid pressure system.

Abstract: In a brake system including a master cylinder and an electrically-driven hydraulic pressure generator with front and rear pistons, when the hydraulic pressure generator cannot be operated and a failure of a first hydraulic system linked to a rear fluid chamber of the generator occurs and makes a first hydraulic system open to the atmosphere, the brake-fluid pressure of a second hydraulic system transmitted from the master cylinder to a wheel cylinder via a front fluid chamber of the generator is used to perform braking. A forward-facing third front cup seal provided at an intermediate portion of the front piston prevents the brake-fluid pressure generated by the master cylinder from leaking out from a front supply port via the rear fluid chamber. At the same time, a stopper prevents the pressure of the front fluid chamber from moving the front piston excessively backward. The braking is accordingly secured by use of the second hydraulic system linked to the front fluid chamber of the motor cylinder.

Abstract: A brake system includes a master cylinder which generates brake fluid pressure by a braking operation of a driver, an electric motor-driven slave cylinder which generates brake fluid pressure based on an electric signal responsive to a braking operation of a driver, and a wheel cylinder for braking a wheel by the brake fluid generated in the master cylinder or slave cylinder. During normal operation of the brake system, the brake fluid generated in the slave cylinder is transferred to the wheel cylinder. During abnormal operation of the brake system, the brake fluid generated in the master cylinder is transferred to the wheel cylinder. The brake system also includes an opening and closing valve in a fluid passage connecting the slave cylinder to the wheel cylinder. When a problem occurs with the slave cylinder, the opening and closing valve is closed for a predetermined amount of time.

Abstract: In a brake-by-wire vehicle brake system that uses a solenoid shut-off valve (24a, 24b), the electric power supplied to the solenoid (33) of the solenoid shut-off valve is controlled so as to decelerate a movement of a plunger (31, 32) of the valve as the plunger reaches a point immediately adjacent to a terminal point thereof. Thereby, a highly responsive property can be achieved while the noises that are generated by the plunger striking a stopper (36) or a valve seat (34) can be minimized. When actuating the plunger in the valve closing direction, the solenoid may receive electric power at a first level, a second level lower than the first level and a third level intermediate between the first and second levels in that order.

Abstract: A VSA device (24), which controls vehicle behavior by individually controlling the pressure of brake fluid supplied from a slave cylinder (23) to a wheel cylinder (16, 17; 20, 23), is provided with: an accumulator (62) which can be connected to the wheel cylinder and the slave cylinder (23); an out-valve (60, 61) disposed on a fluid path between the wheel cylinder and the accumulator (62); a check valve (63) that allows only flow of brake fluid from the accumulator (62) to the slave cylinder (23); and a regulator valve (54) disposed on a fluid path between the wheel cylinder and a path between the check valve (63) and the slave cylinder (23). Brake fluid is discharged from the accumulator (62) to the slave cylinder (23) by reducing the driving force of an electric motor (32) of the slave cylinder (23), thereby rendering a special pump unnecessary and making it possible to reduce the weight, cost, and component count.

Abstract: Under a normal condition, brake fluid pressure generated by a slave cylinder (23) that operates according to operation of a brake pedal (12) is fed to a wheel cylinder (16, 17; 20, 21) to perform braking, while under a fault condition of the slave cylinder (23), brake fluid pressure generated by a master cylinder (11) for backup that operates by the operation of the brake pedal (12) is fed to the wheel cylinder (16, 17; 20, 21) to perform braking. In the latter case, brake fluid fed by a pump (64) is fed to the wheel cylinder (16, 17; 20, 21), before the brake fluid is fed from the master cylinder (11) to the wheel cylinder (16, 17; 20, 21) by a driver depressing the brake pedal (12). Accordingly, without leading to an increase in the stroke of the brake pedal (12), a required amount of brake fluid can be fed to the wheel cylinder (16, 17; 20, 21) to thus ensure a sufficient braking force.

Abstract: In a brake device, when a piston (38A, 38B) of a slave cylinder (23) seizes at an advanced position, an out-valve (60, 61) is opened to discharge brake fluid in a wheel cylinder (16, 17; 20, 21) to a reservoir (62). Then, an in-valve (54, 56) and the out-valve (60, 61) are both closed, and a pump (64) is activated. This allows the brake fluid in the reservoir (62) to be supplied to a fluid pressure chamber (39A, 39B) of the slave cylinder (23), enabling a piston (38A, 38B) of the slave cylinder (23), which has seized at the advanced position, to be pushed back to a retreated position. When the seizure of the piston (38A, 38B) is eliminated in this way, the brake fluid pressure generated in the master cylinder (11) can be supplied to the wheel cylinder (16, 17; 20, 21) via the fluid pressure chamber (39A, 39B) of the slave cylinder (23). Accordingly, it is proposed a method of eliminating seizure of a slave cylinder of a brake device capable of the backup of a failure in the slave cylinder (23).

Abstract: When brake fluid of a first wheel cylinder (39a) of a slave cylinder (23) is increased by supplying the brake fluid to a first wheel cylinder (16, 17) by a first pump (64A), a second piston (38B), which is a free piston, of the slave cylinder (23) moves toward the first fluid pressure chamber (39A) side, the volume of a second fluid pressure chamber (39B) thereby expands, and the brake fluid pressure of a second wheel cylinder (20, 21) can be reduced, whereas when brake fluid pressure of the second fluid pressure chamber (39B) is increased by supplying the brake fluid to the second wheel cylinder (20, 21) by a second pump (64B), the second piston (38B) moves toward the second fluid pressure chamber (39B) side, the volume of the first fluid pressure chamber (39A) thereby expands, and the brake fluid pressure of the first wheel cylinder (16, 17) can be reduced, thus enabling a difference in brake fluid pressure to be freely generated between the first and second wheel cylinders (16, 17).

Abstract: Brake apparatus includes a transmission unit for operatively connecting a brake pedal to a master cylinder, and the transmission unit is a mechanism capable of varying a ratio between an output amount of a push rod connected to a master cylinder and an operation amount of the brake pedal. Further, the transmission unit is constructed in such a manner that, in an initial operation region of the brake pedal, a ratio of the operation amount of the brake pedal to the output amount of the push rod is set to be greater than in another operation region immediately following the initial operation region.

Abstract: During normal operation of a braking force generating device, the wheels are braked by braking force generating device when a depressing force cut-off valve is closed by energizing its solenoid to cut off communication between a master cylinder and wheel cylinders. When an abnormality occurs, a master cylinder generates a brake fluid pressure upon a driver's braking operation, and supplies it to the wheel cylinders when the depressing force cut-off valve is opened by de-energizing its solenoid. When the depressing force cut-off valve is closed, such as during normal operation, since the depressing force cut-off valve functions as a one-way valve that is urged in a valve-closing direction due to a brake fluid pressure generated by the master cylinder, an electromagnetic force generated by the solenoid is smaller, thereby reducing the power consumption of the solenoid.