Abstract: A braking apparatus for a vehicle has a booster for receiving, as a pilot pressure, a pressure of a master cylinder and for regulating a pressure from an auxiliary pressure source to a level predetermined times the pilot pressure. The booster is provided with an initial pressure raising mechanism for causing the booster to output a predetermined initial pressure in response to an initial actuation of a brake pedal.

Abstract: A brake control system for effectively properly performing a braking hydraulic pressure distribution between a front wheel and a rear wheel or a left wheel and a right wheel of a motor vehicle including a master cylinder for generating a hydraulic pressure in response to depression of a brake pedal thereof and applying the hydraulic pressure through first and second braking passages to first and second wheel braking cylinders. This brake control system has first and second pressure control devices respectively coupled to a braking pressure source for allowing the output hydraulic pressures to be regulated independently of each other under control of a control unit. The output of the first pressure control device is coupled through the first braking passage to the first wheel braking cylinder and the output of the second pressure control device is coupled through the second braking passage to the second wheel braking cylinder.

Abstract: When excessive acceleration slip of a driving wheel is detected by wheel speed sensors attached to driving and non-driving wheels, an electronic control unit provides first and second control signals to a change-over valve and a control valve, respectively. The change-over valve operates in accordance with the first control signal to supply hydraulic pressure from a hydraulic pump to control a cut-off valve to thereby cut off communication between a master cylinder and a wheel cylinder. At the same time, hydraulic pressure from the hydraulic pump is fed to the wheel cylinder through the change-over valve and the control valve to brake the driving wheel. The control valve operates in accordance with the second control signal to increase or decrease the pressure in the wheel cylinder thereby adjusting the braking force for the driving wheel.

Abstract: A floating plate is provided in a cylinder chamber and slides freely like a piston. A first group of laminated, ring-shaped, thin-plate piezoelectric elements is provided between a fixed support member provided on part of a wall portion of this cylinder chamber and the floating plate. A second group of laminated, cylindrical, thin-plate piezoelectric elements is provided in the center of the first group and a working member is provided on the free end of the second group of elements that is not attached to the floating plate. A hydraulic chamber is formed in the cylinder chamber on the side of the floating plate opposite to the side on which the first and second groups of elements are provided, and the pressure in this hydraulic chamber pushes the floating plate in the direction of the fixed support member.

Abstract: A piston in a first cylinder is driven as a piezoelectric element group, which includes a plurality of laminar piezoelectric elements stacked in layers, extends or contracts. A second cylinder is formed so as to connect with a first fluid pressure chamber which is defined in the first cylinder by the piston. A piston-shaped valve member is disposed in the second cylinder. The valve member is urged toward the first fluid pressure chamber by a spring. The first fluid pressure chamber is supplied with a fluid whose pressure is set by means of a selector valve. When the selector valve is closed, the fluid pressure chamber is defined as an independent compartment. In this state, high voltage is applied to the piezoelectric element group to elongate it, thereby driving the piston. Thus, the valve member is actuated by the fluid pressure inside the first fluid pressure chamber, and a fluid passage is opened and closed by the valve member.

Abstract: A braking system having a pressure modulator which, during normal braking operation, delivers a fluid pressure which is a predetermined multiple of a fluid pressure generated by the master cylinder to a wheel cylinder. The pressure modulator has a solenoid actuator which is energized during braking force proportioning and anti-skid operations to reduce the delivery pressure. In a preferred embodiment, the pressure modulator further includes another solenoid actuator for increasing the delivery pressure during braking force proportioning operation and for delivering fluid pressure during traction control operation.

Abstract: A fuel injection control apparatus includes a booster apparatus, in which a cylinder chamber is divided into first and second fluid chambers by a piston. The operative area of the piston facing the first fluid chamber is sufficiently greater than that facing the second fluid chamber. Pressurized fuel is supplied to the first fluid chamber through a first check valve. The fluid is delivered from a second fluid chamber to a fuel injection valve via a second check valve. A fluid passage is formed between the first and second fluid chambers. A third check valve is set in the fluid passage, whereby the fuel is allowed to flow only from the first fluid chamber toward the second fluid chamber. The booster piston is located by means of a first piezoelectric device which includes a plurality of piezoelectric elements stacked in layers. When high voltage is applied to the first piezoelectric device to extend it, the piston is moved toward the first fluid chamber.

Abstract: A hydraulic control valve may have a first chamber having an input port, to which an input hydraulic pressure is applied and an output port, and a second chamber having a third port to which a hydraulic control pressure is applied. When a hydraulic pressure below a predetermined level is applied to the first port, the same hydraulic pressure is produced at the second port. When a hydraulic pressure above the predetermined level is applied to the first port, the hydraulic pressure is reduced at a fixed ratio, and thereby a hydraulic pressure lower than the hydraulic pressure applied to the first port is produced at the second port. Thus the hydraulic control valve functions as a proportional valve. When a hydraulic control pressure is applied to the third port, the first and second port are disconnected. Thus the hydraulic control valve functions as a cutoff valve.

Abstract: Wheel cylinders supplied with oil pressure from a master cylinder are respectively provided in brake mechanism provided in wheels of a vehicle. The wheel cylinder has a brake piston provided to form a first fluid chamber to supply oil pressure from the master cylinder, and a brake piston driven by the oil pressure of the first fluid chamber. The wheel cylinder has a piston mechanism formed by laminating thin plate shaped piezoelectric elements, and the piston mechanism is controlled to be expanded or contracted by controlling the voltage applied to the piezoelectric elements to vary the volume of the first fluid chamber.

Abstract: An antiskid control device including a main line system for a usual braking operation and a subline system for an antiskid control, in which the flow rate of the subline system is smaller than the flow rate of the mainline system. The main piping system is provided with a cut-off valve which opens at a usual braking operation and closes at an antiskid control. The subline system is provided with a first control valve for opening the subline system and a second control valve for opening or closing the subline system at an antiskid control. The second control valve opens the subline system to supply a small quantity of brake oil to the wheel cylinder, and closes the subline system to release the brake oil in the wheel cylinder to the outside thereof.

Abstract: A wheel cylinder is formed in the brake caliper for each wheel of a vehicle and brake fluid is supplied from a master cylinder to this wheel cylinder by way of a fluid passage. A brake piston is provided inside the wheel cylinder and includes a piezoelectric piston device inside. By the application of voltage, this piezoelectric piston device expands and contracts the brake piston. A control valve is provided in the fluid passage to open and close it to selectively partition off the master cylinder. When the control valve has closed the passage, a voltage is applied to the piezoelectric piston device to expand it and control the pressure acting on the brake piston in the wheel cylinder to vary the braking force.