Electric linear actuator

Patent metadata

Field	Value
Publication number	US-9841090-B2
Application number	US-201514953316-A
Country	US
Kind code	B2
Filing date	Nov 28, 2015
Priority date	May 29, 2013
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

An electric linear actuator has an electric motor, a speed reduction mechanism, and a ball screw mechanism to convert rotational motion of the electric motor to an axial linear motion of a drive shaft. The ball screw mechanism nut and screw shaft both include helical screw grooves with a large number of balls between them. The housing has a first housing portion and a second housing portion. The electric motor is mounted on the first housing portion. The second housing portion abuts an end face of the first housing portion. The first housing portion has a cylindrical gear containing portion to contain the speed reduction mechanism. An end part of the gear containing portion extends radially inward to form a bottom portion to cover the speed reduction mechanism. The bottom portion of the first housing portion and the second housing portion are formed, respectively, with abutment surfaces.

First claim

What is claimed is:

1. An electric linear actuator comprising:
a housing;
an electric motor including a shaft mounted on the housing;
a speed reduction mechanism coupled with the electric motor shaft for reducing the rotational speed of the electric motor and transmitting the rotational power of the electric motor to a ball screw mechanism to convert the rotational motion of the electric motor to axial linear motion of a drive shaft;
the ball screw mechanism comprising:
a nut formed with a helical screw groove on its inner circumference, the nut is rotationally but axially immovably supported by rolling bearings mounted on the housing;
a screw shaft is coaxially integrated with the drive shaft, the screw shaft includes a helical screw groove on its outer circumference corresponding to the helical screw groove of the nut, the screw shaft is inserted into the nut via a large number of balls, the screw shaft is axially movably but not rotationally supported relative to the housing;
the housing comprises a first housing portion and second housing portion, the electric motor is mounted on the first housing portion, the second housing portion abuts against an end face of the first housing portion;
the first housing portion includes an extending cylindrical gear containing portion encircling the electric motor shaft and a speed reduction mechanism to contain the speed reduction mechanism;
an end part of the gear containing portion of the first housing extends radially inward to form a bottom portion positioned beyond the electric motor shaft to cover at least a portion of an input gear of the speed reduction mechanism; and
the bottom portion of the first housing portion and the second housing portion are formed, respectively, with abutment surfaces.

2. The electric linear actuator of claim 1 , wherein each of the abutment surfaces, respectively, of the first and second housing portions includes a substantially circular configuration.

3. The electric linear actuator of claim 1 , wherein at least one of the abutment surfaces of the first and second housing portions include an annular sealing groove and a sealing member is interposed between the abutment surfaces of the housing.

4. The electric linear actuator of claim 3 , wherein the sealing member is a liquid gasket formed of curable material.

5. The electric linear actuator of claim 3 , wherein the sealing member is an O-ring.

6. The electric linear actuator of claim 1 , wherein the first housing portion and the second housing portion are united with each other by a plurality of fastening bolts, a plurality of securing portions on one of the first or second housing portions is formed with bolt apertures that enable passage of the fastening bolts, the plurality of securing portions partially projected from a periphery of the first and second housing portions, and wherein the bolt apertures are arranged equidistantly along the periphery of the first or second housing portions.

7. The electric linear actuator of any one of claim 1 , wherein at least the second housing portion of the first and second housing portions includes ribs, each rib extending over a region from a securing portion to a cylindrical portion of the second housing portion to contain the screw shaft.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• FUNADA Kensuke

Classifications

• F16H2025/2031

  Actuator casings · CPC title

• F16J15/14

  by means of granular or plastic material, or fluid · CPC title

• F16H25/2204 Primary

  with balls · CPC title

• F16H2025/2081

  Parallel arrangement of drive motor to screw axis · CPC title