Hitachi Automotive Systems, Ltd.

Hitachi Astemo Ltd.

Atsushi Odaira

Takuya Usui

Takayasu Sakashita

Kunihiro Matsunaga

Jun Watanabe

Mitsuhiro Endo

Hiroshi Shigeta

Shinji Shimizu

Takayuki Hagiwara

Naoki Shirakawa

Rikiya Yoshizu

Satohiro Koi

Takashi Mitsugi

Daisuke Hibi

Koichi Sakimoto

Hao Yu

The present disk brake includes a carrier fixed to a non-rotatable portion of a vehicle, a caliper attached to this carrier and including a piston configured to press an inner brake pad, a slide pin fixed to any of the carrier and the caliper and configured to allow the caliper to slidably move relative to the carrier in an axial direction of a wheel, and a driving mechanism including an electric motor and a speed reduction mechanism and configured to transmit a driving force of the electric motor to the piston via the speed reduction mechanism. At least a part of the driving mechanism is disposed on an extension of an axis of the slide pin. This configuration can prevent an increase in the size of the present disk brake, thereby improving the mountability thereof onto a vehicle.

Disk brake

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.

Disc brake and planetary gear reduction mechanism

An electric motor-driven brake apparatus has speed reduction mechanisms transmitting rotational force of an electric motor, a ball screw mechanism converting rotational force of the speed reduction mechanisms into a thrust, a piston propelled by the ball screw mechanism, and a caliper movably supporting the piston. The ball screw mechanism has a base nut non-rotatably supported relative to the caliper. The ball screw mechanism further has a push rod receiving rotational force from the speed reduction mechanisms. The push rod is movable relative to the base nut in the axial direction of the push rod. Consequently, it is possible to reduce the axial length of the cylinder portion of the caliper body, and hence possible to attain a size reduction. Accordingly, it is possible to improve the mountability of the electric motor-driven brake apparatusonto vehicles.

Electric motor-driven brake apparatus

An object of the present invention is to provide an electric disc brake suitable for improving responsiveness. The electric disc brake includes: a rotation linear motion conversion mechanism configured to convert rotational motion of the rotary member into linear motion; a return spring configured to store torque for retreating the piston according to rotation of a rotary member; and a clutch configured to make a transition between a state in which the torque is able to be stored in the return spring and a state in which storage of the torque in the return spring is deterred. The clutch includes: a first disc and a third disc configured to rotate together with the rotary member, and a second disc disposed between the first disc and the third disc. The return spring has one end portion coupled to the caliper body and another end portion coupled to the second disc.

Electric disc brake

Provided is an electric booster capable of detecting a movement position of an input member in a wide range along an axial direction. The electric booster includes an input rod formed of a magnetic material, an input plunger formed of a non-magnetic material, and an input piston formed of a magnetic material. A stroke detector includes respective magnet members arranged so that magnetic poles are aligned along a movement direction of the input plunger, and a Hall sensor unit that is fixed to a housing, and detects a movement position of the input plunger in accordance with a magnetic flux density from the respective magnet members. As a result, a flat magnetic flux distribution having a wide region along the axial direction is provided, and the movement position of the input plunger can be detected relatively precisely in a wide range along the axial direction.

Electric booster and stroke detector

An electric motor is controlled according to the back and forth movement of an input rod, which is caused by brake pedal operation; a primary piston is propelled to generate hydraulic brake pressure in a master cylinder; and the hydraulic brake pressure is fed back to the input rod through an input piston. The input piston is resiliently held by springs with respect to the primary piston. A jump-in clearance is created between the input piston and the input rod by a rearward spring. At the initial stage of braking, hydraulic brake pressure is not transmitted to the input rod due to the jump-in clearance, which provides jump-in characteristics. The jump-in clearance can be set, regardless of the amount of a relative displacement between the primary piston and the input piston, so that the range of adjustment for regenerative braking can be set larger than the jump-in clearance.

Electric booster

An abutment-plate portion of a main body portion of a biasing member, which faces a disc rotor in an axial direction, includes a pad-return portion for biasing a friction pad in a direction separating apart from the disc rotor, and upper and lower claw portions which are located separately on the upper and lower sides of the pad-return portion. The upper and lower claw portions of the biasing member are brought into abutment against upper and lower groove portions respectively with a frictional resistance When a lining of the friction pad is worn away and the friction pad is pressed in a direction approaching to the disc rotor in accordance with the wear of the lining, the movement of the entire biasing member in the direction approaching to the disc rotor inside a pad guide is allowed by the upper and lower claw portions serving as wear-following portions.

Disc brake apparatus

A ball-and-ramp mechanism of a thrust generator includes a rotary ramp member and a rectilinear ramp member, each having a plurality of sloped grooves sloped along a circumferential direction and having an arcuate diametrical cross-section, and a spherical member interposed between the sloped grooves of the ramp members to transmit force from the rotary ramp member to the rectilinear ramp member. Each of the sloped grooves has regions varying in the curvature radius of the diametrical cross-section in a track area where the spherical member contacts the sloped groove. Accordingly, it is possible to improve the durability of the rotary ramp member and the rectilinear ramp member.

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Yokohama, Japan

Atsushi Odaira