Ntn Corporation

Masaaki Eguchi

Tatsuya Yamasaki

Makoto Muramatsu

Yui Masuda

Tomomi Goto

Makoto Yasui

Yuki Saoyama

Yuuki Saoyama

Tomoaki Makino

Katsuhisa Yamaguchi

An electromechanical brake system includes a linear motion mechanism configured to convert the rotation transmitted from the electric motor to a linear motion, thereby pressing a friction pad against a brake disk; a linear motion mechanism housing in which the linear motion mechanism is received as a single assembly with the components of the linear motion mechanism assembled together; and a caliper body shaped to extend across the outer periphery of the brake disk. The caliper body includes a claw portion axially supporting a friction pad; a housing-fixing plate which is arranged on the side of the linear motion mechanism housing opposite from the brake disk; and an outer shell portion through which the claw portion and the housing-fixing plate are coupled together.

Electromechanical brake system

An electromechanical brake system includes a caliper body having a housing portion in which is received a linear motion mechanism for pressing a brake pad against a brake disk. A boot is coupled at its one end to an outer ring member of the linear motion mechanism, and at its other end to a support ring. The support ring abuts and is mechanically and fixedly fastened to an open end surface of the housing portion to close the open end of housing portion with the support ring and the boot.

An electric linear motion actuator is provided which includes an outer ring member, a rotary shaft, planetary rollers, and a carrier including a disk, and in which the outer ring member is formed with a helical rib, each of the planetary rollers being formed with circumferential grooves in which the helical rib is engaged. When the rotary shaft rotates, the planetary rollers rotate about their axes while revolving around the rotary shaft so that the outer ring member axially linearly moves. The actuator includes thrust roller and retainer assemblies each mounted between one of the planetary roller and the disk of the carrier, and each guided by a raceway, i.e., an end surface of the corresponding planetary roller. The actuator includes a common raceway disk common to all of the thrust roller and retainer assemblies, and mounted between the thrust roller and retainer assemblies and the disk of the carrier.

Electric linear motion actuator and electromechanical brake system

An electric brake device includes an electric motor; a braking force application mechanism configured to apply a braking force on a vehicle wheel; a lock mechanism configured to assume one of a locked condition; a temperature sensor configured to measure an ambient temperature of a vehicle; and a freezing preventive power supply unit configured to initiate supply of an electric power to the electric motor or a drive source of the lock mechanism. The freezing preventive power supply unit interrupts the supply of the electric power to the electric motor or the drive source of the lock mechanism when the temperature detected by the temperature sensor exceeds a second preset temperature Tthat is higher than a first preset temperature T

Electric brake device

An electric linear motion actuator includes planetary rollers mounted between the radially inner surface of an outer ring member and the radially outer surface of a rotary shaft, and a carrier rotatable about the rotary shaft and including radially movable roller shafts rotatably supporting the respective planetary rollers. Elastic rings each having circumferentially separate ends are each wrapped around the roller shafts to radially inwardly bias the roller shafts, thereby bringing the respective planetary rollers into elastic contact with the radially outer surface of the rotary shaft. Each elastic ring is prevented from rotating relative to the roller shafts, thereby preventing one of the roller shafts from being axially aligned with the gap between the circumferential separate ends, causing the elastic ring to be radially compressed and thus making it impossible for the elastic rings to radially bias the roller shafts.

Electric linear motion actuator and electric disk brake system

A linear motion actuator includes an outer ring member mounted in a housing, a rotary shaft rotated by a motor, planetary rollers mounted between the outer ring member and the shaft and supported by a carrier rotatable about the shaft. A helical rib is formed on the inner surface of the outer ring member which is engaged in helical grooves formed in outer surfaces of the planetary rollers. When the shaft rotates, the planetary rollers rotate and revolve, thereby axially moving the outer ring member. Uneven axial loads applied to the planetary rollers from the outer ring member are supported by thrust bearings disposed between the planetary rollers and an inner disk of the carrier. Aligning seats are provided between each opposed pair of the planetary rollers and the thrust bearings such that the contact surfaces of the aligning seats shift relative to each other under the uneven axial loads.

An electric brake device includes an electric motor, a braking force application mechanism, a lock mechanism, a temperature sensor for measuring an ambient temperature of a vehicle in which the electric brake device is provided, and a freezing preventive power supply unit. The freezing preventive power supply unit initiates the supply of an electric power to the electric motor or a drive source of the lock mechanism in the event that while the braking force application mechanism applies a braking force and the lock mechanism is held in a locked condition, the temperature sensor detects a preset temperature of the electric brake device immediately before freezing.

A linear motion actuator has an output member that can be smoothly moved linearly even when lateral moment acts on the output member. A carrier () supporting planetary rollers () is axially immovable, while an outer ring member (), as the output member, is axially slidably fitted in the radially inner surface of a cylindrical portion () of a housing (), and is rotationally fixed to a driven member through keys (). Hard plating layers are formed on the radially outer surface of a rotary shaft (), the radially outer surfaces of the planetary rollers (), including helical grooves (), and the surface of a helical rib member () which is fixed to the radially inner surface of the outer ring member () forming a helical rib.

An electric linear motion actuator includes: a rotary shaft to be driven by an electric motor; a plurality of planetary rollers kept in rolling contact with a cylindrical surface formed on an outer periphery of the rotary shaft; a carrier which retains the planetary rollers such that the planetary rollers are rotatable about axes thereof while revolving around the rotary shaft, and of which axial movement is restricted; and an outer ring member surrounding the planetary rollers and supported so as to be slidable in an axial direction. Helical ribs are formed on an inner periphery of the outer ring member; and circumferential grooves are formed on an outer periphery of each of the planetary rollers so as to be engaged with the helical ribs. A rotation of the rotary shaft is thus converted to a linear motion of the outer ring member.

Electric linear motion actuator

An electric linear motion actuator is provided which can set the clearance during normal braking operation of an electric brake system. The linear motion actuator includes a load sensor for detecting the magnitude of the load with which a friction pad is pressed against the brake disk, a temperature sensor for compensating for the influence of temperature on the load sensor, and an electronic control unit. The electronic control unit is adapted to calculate a target rotational angle from the position of the electric motor corresponding to the magnitude of the load detected by the load sensor to the position of the electric motor where the clearance is at a predetermined value, and control the electric motor to rotate the electric motor by the target rotational angle.

Electric linear motion actuator and electric brake system

A disk brake system includes a disk, brake pads, and a linear motion actuator including an electric motor, a rotary shaft coupled to the motor through a reduction gear mechanism, planetary rollers formed with helical grooves in their outer surfaces, and an outer ring member having a helical rib engaged in the helical grooves. The outer ring is coupled to one of the brake pads. When the rotary shaft is rotated by the motor, the outer ring member is moved axially through the planetary rollers, and the brake pads are pressed against the disk. The linear motion actuator further includes a locking mechanism including engaging holes formed in an intermediate gear of the reduction gear mechanism at equal intervals, a locking pin, and a linear solenoid for moving the locking pin until the pin engages in one of the engaging holes, thus locking the motor.

An electric brake system is proposed which includes an electric linear motion actuator and can generate the required braking force with high accuracy. A load sensor () is provided in a motion converting mechanism of the actuator which converts the rotary motion of a rotary shaft () to which the rotation of an electric motor () is transmitted to linear motion of an outer ring member () as an output member. The load sensor () detects the pushing force with which the outer ring member () linearly drives a driven member. With this arrangement, if the driven member is a braking member of an electric brake system, it is possible to directly detect the braking force applied by the driven member and thus to accurately generate the required braking force.

In an electric linear motion actuator, it is proposed to uniformly distribute external thrust loads to respective planetary rollers while the planetary rollers are revolving around a rotary shaft while rotating about their respective axes with a helical rib of an outer ring member in engagement with circumferential grooves of the respective planetary rollers. The planetary rollers have bearing support surfaces on which thrust bearings are supported, respectively. The distance from the bearing support surface of each planetary roller to a predetermined reference position of each circumferential groove () of the planetary roller is different from the corresponding distances for the other planetary rollers, whereby with the planetary rollers supported by the respective thrust bearings, the axial position of each circumferential groove coincides with the axial position of the portion of the helical rib of the outer ring member that is engaged in the circumferential groove.

Electric linear motion actuator and electric disc brake assembly

In an electric linear motion actuator, planetary rollersrotatably supported on their radially inner surfaces by respective support pinsare radially inwardly biased by radially compressible ring springsenveloping the support pins, thereby biasing and pressing the respective planetary rollersagainst the radially outer surface of a rotary shaft. Thus, it is possible to stably transmit torque of the rotary shaftto the respective planetary rollerswithout applying a preload to the planetary rollerswith a negative gap between the radially outer surface of the rotary shaftand the radially inner surface of the outer ring member

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Iwata, Japan

Masaaki Eguchi