Electric actuator and gear mechanism

Patent metadata

Field	Value
Publication number	US-9976639-B2
Application number	US-201615012430-A
Country	US
Kind code	B2
Filing date	Feb 1, 2016
Priority date	Feb 3, 2015
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

An electric actuator to be mounted on an object having a stationary section and a movable section is provided. The electric actuator is configured to actuate the movable section of the object. The electric actuator is provided with a case fixedly attached to the stationary section, and includes a gear mechanism provided in the case. The gear mechanism includes a rotational member rotatable about a common axis and connected with a first motor, an internal gear formed in the rotational member, a sun gear rotatable about the common axis and connected with a second motor, and a planetary gear provided between the internal gear and the sun gear. The planetary gear is connected with an output section for actuating the movable section of the object. The rotational member is rotatably supported a bearing provided between an inner surface of the case and an outer surface of the rotational member.

First claim

What is claimed is:

1. An electric actuator to be mounted on an object having a stationary section and a movable section, the electric actuator for actuating the movable section of the object and comprising:
a case fixedly attached to the stationary section of the object, the case comprising a wall defining an enclosed space and having an outlet hole therein;
a first motor configured for generating a first actuating power;
a second motor configured for generating a second actuating power;
an output section configured for outputting an actuating power comprising the first actuating power and/or the second actuating power, the output section having an output body provided in the enclosed space and an extending portion projecting outside of the case through the outlet hole and connected with the movable section of the object;
a position sensor for sensing a position of the output section;
a controller configured for controlling the first motor and the second motor in accordance with a sensed position of the output section; and
a gear mechanism provided in the enclosed space of the case, the gear mechanism comprising:
a rotational member configured to be rotatable about a common axis and connected with the first motor,
a bearing provided between an inner surface of the wall and an outer surface of the rotational member to rotatably support the rotational member;
an internal gear formed in the rotational member;
a sun gear configured to be rotatable about the common axis and connected with the second motor; and
a planetary gear provided between the internal gear and the sun gear and connected with the output body,
wherein the rotational member, the internal gear, and the planetary gear define a first power transmission path for transmitting the first actuating power from the first motor to the output section, and
wherein the sun gear and the planetary gear define a second power transmission path for transmitting the second actuating power from the second motor to the output section.

2. The electric actuator of claim 1 , wherein respective axes of the first motor, the rotational member, the second motor, the sun gear, and the planetary gear are parallel to one another.

3. The electric actuator of claim 2 , further comprising:
a first sun gear configured to be rotated by the first motor;
at least one first planetary gear meshing with the first sun gear; and
a first internal gear having internal teeth that meshes with the at least one first planetary gear, and rotation of the first internal gear being restrained,
wherein the rotational member rotates in accordance with revolution of the at least one first planetary gear around an axis of the first sun gear.

4. The electric actuator of claim 3 , wherein the controller is configured for controlling electric current supply to the first motor to stop the operation of the first motor and controlling electric current supply to the second motor to continue the rotation of the second sun gear, when the at least one first planetary gear becomes unrotatable on its axis.

5. The electric actuator of claim 3 , wherein the controller is configured for controlling electric current supply to the first motor and the second motor, wherein the electric current supply is stopped to one of the first motor and the second motor for which the respective planetary gear becomes unrotatable on its axis, while the electric current supply is continued to the other of the first motor and the second motor for which the respective planetary gear is still rotatable on its axis.

6. The electric actuator of claim 3 , wherein the controller is configured for controlling the first motor and the second motor to rotate the output section, wherein the output section is configured to rotate in a first direction by one of the first motor and the second motor and to rotate in a second direction opposite to the first direction by the other of the first motor and the second motor.

7. The electric actuator of claim 3 , wherein the first internal gear is fixedly attached to the case to keep the first internal gear from rotating relative to the case.

8. The electric actuator of claim 3 , wherein the at least one first planetary gear is directly coupled to the rotational member, and wherein the planetary gear is directly coupled to the output section.

9. The electric actuator of claim 1 , wherein the first motor and the second motor are arranged in the enclosed space of the case.

10. The electric actuator of claim 1 , wherein the first motor and the second motor are arranged outside of the case.

Assignees

• Nabtesco Corp

Inventors

• Yasui Tsutomu

Classifications

• F16H35/10 Primary

  Arrangements or devices for absorbing overload or preventing damage by overload · CPC title

• B64C13/34

  using toothed gearing · CPC title

• F16H1/46

  Systems consisting of a plurality of gear trains each with orbital gears, {i.e. systems having three or more central gears} · CPC title

• F16H37/0826

  with only one output shaft · CPC title

• Y02T50/40

  Weight reduction · CPC title