Brake actuator

Patent metadata

Field	Value
Publication number	US-11332113-B2
Application number	US-201916686267-A
Country	US
Kind code	B2
Filing date	Nov 18, 2019
Priority date	Nov 21, 2018
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

A brake actuator includes: a housing; an electric motor with a hollow motor shaft rotating; a rotating shaft disposed inside the motor shaft to be coaxial therewith; a piston with a rear end disposed inside the motor shaft and a front end engaged with the friction member; a speed reduction mechanism decelerating rotation transmitted from the motor shaft and transmitting the rotation to the rotating shaft; and a motion conversion mechanism converting a rotating motion of the rotating shaft into an advancing/retracting motion of the piston. The motor shaft is rotatably supported by the housing at an outer peripheral surface thereof, and the rotating shaft is rotatably supported by an inner peripheral surface of the motor shaft via rollers at an outer peripheral surface thereof as well as by the housing via a thrust bearing at a rear end of the rotating shaft.

First claim

What is claimed is:

1. A brake actuator for pressing a friction member against a rotating body that rotates with a vehicle wheel, the brake actuator comprising:
a housing;
an electric motor in which a hollow motor shaft rotates;
a rotating shaft disposed inside the motor shaft so as to be coaxial with the motor shaft;
a piston having a rear end that is disposed inside the motor shaft and a front end that is engaged with the friction member;
a speed reduction mechanism configured to decelerate rotation transmitted from the motor shaft and transmit the rotation to the rotating shaft; and
a motion conversion mechanism configured to convert a rotating motion of the rotating shaft into an advancing and retracting motion of the piston, wherein
the motor shaft is rotatably supported by the housing at an outer peripheral surface of the motor shaft, and the rotating shaft is rotatably supported by an inner peripheral surface of the motor shaft via rollers at an outer peripheral surface of the rotating shaft as well as rotatably supported by the housing via a thrust bearing at a rear end of the rotating shaft, wherein:
the speed reduction mechanism includes a first internal planetary gear mechanism and a second internal planetary gear mechanism, the first internal planetary gear mechanism having a first internal gear and a first external gear that contacts the first internal gear from inside to mesh with the first internal gear, the second internal planetary gear mechanism having a second internal gear and a second external gear that contacts the second internal gear from inside to mesh with the second internal gear; and
the speed reduction mechanism includes a planetary gear body that is rotatably supported by an eccentric shaft portion of the motor shaft and in which one of the first internal gear and the first external gear and one of the second internal gear and the second external gear are disposed side by side in an axial direction, and the other of the first internal gear and the first external gear is provided on the housing, and the other of the second internal gear and the second external gear is provided on the rotating shaft.

2. The brake actuator according to claim 1 , wherein the first internal gear and the second internal gear each have an arc-shaped tooth profile, and the first external gear and the second external gear each have an epitrochoidal parallel curved tooth profile.

3. The brake actuator according to claim 1 , wherein the eccentric shaft portion, by which the planetary gear body is rotatably supported, is provided at a rear end of the motor shaft, the rotating shaft has a flange at the rear end of the rotating shaft, and an outer periphery of the flange is provided with the other of the second internal gear and the second external gear.

4. The brake actuator according to claim 1 , wherein the first internal gear is fixedly supported by the housing, the first external gear is provided on an outer periphery of the planetary gear body, the second internal gear is provided on an inner periphery of the planetary gear body, and the second external gear is provided on the rotating shaft.

5. A brake actuator for pressing a friction member against a rotating body that rotates with a vehicle wheel, the brake actuator comprising:
a housing;
an electric motor in which a hollow motor shaft rotates;
a rotating shaft disposed inside the motor shaft so as to be coaxial with the motor shaft;
a piston having a rear end that is disposed inside the motor shaft and a front end that is engaged with the friction member;
a speed reduction mechanism configured to decelerate rotation transmitted from the motor shaft and transmit the rotation to the rotating shaft; and
a motion conversion mechanism configured to convert a rotating motion of the rotating shaft into an advancing and retracting motion of the piston, wherein
the motor shaft is rotatably supported by the housing at an outer peripheral surface of the motor shaft, and the rotating shaft is rotatably supported by an inner peripheral surface of the motor shaft via rollers at an outer peripheral surface of the rotating shaft as well as rotatably supported by the housing via a thrust bearing at a rear end of the rotating shaft, wherein:
the motion conversion mechanism includes
one of an external thread and an internal thread, which is provided on the rotating shaft, and
a movable body that has the other of the external thread and the internal thread that is screwed with the one of the external thread and the internal thread, that is non-rotatable and configured to advance and retract, and that comes into contact with the piston; and

radial displacement of contact faces of the movable body and the piston is permitted, the contact faces contacting each other.

6. The brake actuator according to claim 5 , wherein the contact faces of the movable body and the piston constitute a part of a spherical surface centered on a point on an axis of the brake actuator, the contact faces contacting each other.

Assignees

• Toyota Motor Co Ltd

Inventors

• Ikuma Nao
• Nanahara Masaki
• Yabusaki Naoki

Classifications

• F16H2001/324

  comprising two axially spaced, rigidly interconnected, orbital gears · CPC title

• F16D2125/40

  Screw-and-nut · CPC title

• F16H1/32

  in which the central axis of the gearing lies inside the periphery of an orbital gear · CPC title

• F16C19/188

  with at least one row for radial load in combination with at least one row for axial load · CPC title

• F16D2121/24

  using motors · CPC title