Abstract: The present disk brake includes a braking force holding mechanism configured to restrict a rotation of a rotational shaft (a ratchet gear) to hold a braking force based on driving of a solenoid actuator. The braking force holding mechanism includes a holding member configured to move based on the driving of the solenoid actuator to restrict the rotation of the ratchet gear, and an engagement member coupled with this holding member. The engagement member is rotatably supported on a gear housing portion, and is configured to prohibit a movement of the holding member. Due to this configuration, an excitation force applied from outside to the holding member can be canceled out with the aid of the engagement member, and thus the disk brake can realize a size reduction and achieve cost saving.

Abstract: To provide a disc brake having a planetary gear reduction mechanism that may be satisfactory costly and achieve improved reliability, a planetary gear reduction mechanism of a disc brake according to the present disclosure includes a sun gear having an input gear portion to which rotation from a motor is transmitted and an output gear portion extending axially from a radial central region of the input gear portion, a plurality of planetary gears configured to mesh with the output gear portion of the sun gear, and an internal gear configured to mesh with each planetary gear, and the internal gear has a cylindrical support portion configured to rotatably support the sun gear. Accordingly, at the time of assembly, the axis of the sun gear and the axis of the internal gear may be arranged substantially concentrically, which may result in improved reliability and cost satisfaction.

Abstract: To provide a disc brake having a planetary gear reduction mechanism that may be satisfactory costly and achieve improved reliability, a planetary gear reduction mechanism of a disc brake according to the present disclosure includes a sun gear having an input gear portion to which rotation from a motor is transmitted and an output gear portion extending axially from a radial central region of the input gear portion, a plurality of planetary gears configured to mesh with the output gear portion of the sun gear, and an internal gear configured to mesh with each planetary gear, and the internal gear has a cylindrical support portion configured to rotatably support the sun gear. Accordingly, at the time of assembly, the axis of the sun gear and the axis of the internal gear may be arranged substantially concentrically, which may result in improved reliability and cost satisfaction.

Abstract: Provided is an electric booster which can be downsized by enhancing space efficiency while reducing the effect of a magnetic field from outside on a magnetic sensor by means of a magnetic shield. The stroke amount of an input plunger 29 connected to a brake pedal 6 is detected by a stroke detection sensor. The operation of an electric motor is controlled by controller on the basis of the stroke amount of the input plunger to thrust a primary piston through a ball screw mechanism, and brake fluid pressure is thus generated by a master cylinder 4. The stroke detection device uses a Hall IC to detect magnetic flux densities from first and second magnet members mounted on the input plunger to obtain the stroke of the input plunger. The first and second magnet members and the Hall IC are disposed inside a linear-motion member formed of a cylindrical magnetic body of the ball screw mechanism to be magnetically shielded.

Abstract: Provided is an electric booster which can be downsized by enhancing space efficiency while reducing the effect of a magnetic field from outside on a magnetic sensor by means of a magnetic shield. The stroke amount of an input plunger 29 connected to a brake pedal 6 is detected by a stroke detection sensor. The operation of an electric motor is controlled by controller on the basis of the stroke amount of the input plunger to thrust a primary piston through a ball screw mechanism, and brake fluid pressure is thus generated by a master cylinder 4. The stroke detection device uses a Hall IC to detect magnetic flux densities from first and second magnet members mounted on the input plunger to obtain the stroke of the input plunger. The first and second magnet members and the Hall IC are disposed inside a linear-motion member formed of a cylindrical magnetic body of the ball screw mechanism to be magnetically shielded.

Abstract: The disclosed invention provides a synchronous motor driving system that reduces vibration attributed to a temporal second-order component of radial electromagnetic force in a three-phase synchronous motor and controls a d-axis current and a q-axis current to reduce noise that is produced as a result of vibration resonating with a structure. A motor driving system of the present invention causes a predefined negative d-axis current to flow into a motor in which a q-axis current is less than or equal to a predefined current value and d-axis inductance and q-axis inductance match substantially. The motor driving system causes a predefined negative d-axis current to flow into a motor in which d-axis inductance and q-axis inductance differ and causes the negative d-axis current to increase with an increase in the q-axis current.

Abstract: An electric motor is controlled according to an operation of a brake pedal connected to an input rod to drive a ball-screw mechanism through a transmission mechanism, thereby propelling a primary piston and a subpiston to generate brake hydraulic pressure in a master cylinder. The brake hydraulic pressure in the master cylinder is received with an input piston and transmitted to the brake pedal through a plunger rod and the input rod. The input rod and the plunger rod are tiltably connected, through a ball joint, and the plunger rod is axially slidably guided by a guide part of a rear cover. Thus, a lateral force acting on the primary piston or the subpiston is reduced to prevent an increase in sliding resistance and degradation of sealing performance.