Electric actuator and a motor used therein

• US 20060238048A1
• Filed: 04/25/2006
• Published: 10/26/2006
• Est. Priority Date: 04/26/2005
• Status: Active Grant

• Current Assignee: Igarashi Electric Works Ltd., Mitsui Kinzoku Act Corporation (Mitsui Mining & Smelting Co., Ltd.)
• Original Assignee: Igarashi Electric Works Ltd., Mitsui Mining and Smelting Company Limited
• Inventors: Kurihara, Hiroyuki, Watanabe, Yoshihisa, Yokomori, Kazuhito, Tanaka, Katuyuki, Sesita, Naoto, Mizukoshi, Yusuke
• Granted Patent: US 7,339,299 B2
• Time in Patent Office: Days
• US Class Current: 310/88
• CPC Class Codes: H02K 15/14 Casings; Enclosures; Supports
• CPC Class Codes: H02K 2213/09 Machines characterised by the presence of elements which are subject to variation, e.g. adjustable bearings, reconfigurable windings, variable pitch ventilators
• CPC Class Codes: H02K 5/10 with arrangements for protection from ingress, e.g. water or fingers
• CPC Class Codes: H02K 5/15 Mounting arrangements for bearing-shields or end plates
• CPC Class Codes: H02K 5/24 specially adapted for suppression or reduction of noise or vibrations
• CPC Class Codes: H02K 7/081 specially adapted for worm gear drives H02K7/09 takes precedence
• CPC Class Codes: H02K 7/1166 comprising worm and worm-wheel structural association with bearings specially adapted for worm gear drives H02K7/081
• CPC Class Codes: Y10T 74/19828 Worm

Abstract

A motor comprises a rotor fixed to a shaft and a stator comprising a permanent magnet on the inner circumferential surface of a motor casing. The shaft extends from the opening end of the motor casing and has a worm wheel in a gear casing. The end face of the gear casing has an annular projection. The motor casing has an outward flange at the opening end. When the motor casing is connected with the gear casing, an elastic O-ring is fitted between a space formed by the outer circumferential surface of the annular projection, an outer vertical seat face of the gear casing and a corner of the outward flange thereby achieving suitable alignment of the motor casing with the gear casing. The permanent magnet is made of Nd magnet which is pressingly fitted on the inner circumferential surface of the motor casing.

Claims

1. An electric actuator comprising:

a motor;

a motor casing including the motor and having a closed end and an opening end having an outward flange having a inner corner;

a shaft driven by the motor and extending from the opening end of the motor casing, said shaft having a worm wheel an en extended part; and

a gear casing including the worm wheel of the shaft, said gear casing having an end face that faces the opening end of the motor casing, an annular projection being axially formed on the end face of the gear casing and having an outer circumferential surface, a vertical seat face extending from the annular projection outwards, an elastic O-ring being put into a space formed by the seat face of the gear casing and the outer circumferential surface of the annular projection and the inner corner of the outward flange of the motor casing.

2. An electric actuator as claimed in claim 1 wherein an inner corner is rounded.

3. An electric actuator as claimed in claim 2 wherein the O-ring has diameter slightly smaller than an external diameter of the annular projection to achieve tight-fitting of the O-ring.

4. An electric actuator as claimed in claim 2 wherein a traverse section of the O-ring is slightly larger than an area of the space formed by the seat face of the gear casing, the outer circumferential surface of the annular projection and the inner corner.

5. An electric actuator as claimed in claim 2 wherein a pair of ears projects from the opening end of the motor casing at a position on a diagonal line symmetrical with an axis of the shaft, said pair of ears having first holes respectively, the end face of the gear casing having second holes, a bolt being threaded to each of the second holes through each of the first holes so that the motor casing is pressingly connected to the gear casing.

6. An electric motor comprising:

a motor casing having an inner circumferential surface;

a shaft axially extending in the casing;

a rotor fixed to the shaft; and

a stator comprising a permanent magnet pressingly fitted on the inner circumferential surface of the motor casing, said stator facing and surrounding the rotor, said permanent magnet being made of Nd—

Fe—

B magnet having an inner circumferential surface on which a plurality of N- and S-poles are alternately spaced equally.

7. An electric motor as claimed in claim 6 wherein an external diameter of the permanent magnet is slightly larger than an internal diameter of the motor casing to achieve tight-fitting of the magnet on the inner circumferential surface of the motor casing with heating.