Grounding device for preventing electrolytic corrosion in the bearings of rotary electric machines

• US 4,515,417 A
• Filed: 09/15/1983
• Issued: 05/07/1985
• Est. Priority Date: 11/24/1982
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Shiraishi, Akiyoshi
• Primary Examiner(s): Footland, Lenard A.
• Application Number:
  US06/532,592
• Time in Patent Office: 600 Days
• Field of Search: 308/189 R, 308/207 R, 308/189 A, 308/207 A, 384/135, 384/136, 384/94
• US Class Current: 384/445
• CPC Class Codes: F16C 19/06 with a single row or balls
• CPC Class Codes: F16C 19/52 with devices affected by abnormal or undesired conditions
• CPC Class Codes: F16C 2380/26 Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators in general H02K
• CPC Class Codes: F16C 41/002 Conductive elements, e.g. to prevent static electricity
• CPC Class Codes: H02K 11/40 Structural association with grounding devices
• CPC Class Codes: H02K 5/1732 radially supporting the rotary shaft at both ends of the rotor H02K5/1737 takes precedence

Abstract

A grounding device for preventing electrolytic corrosion in the bearings of rotary electric machines including a bearing which supports the shaft of a rotor in a stator which is grounded, an electrically conductive end cover which is mounted on the stator so as to surround the bearing and a centrifugal contact point which is mounted on the shaft, which is in contact with the end cover when the machine is standing still or rotating at low speeds to short-circuit the shaft and the end cover, and which breaks the short-circuited condition as the running speed of the shaft increases.

Claims

1. A rotary machine having a grounding device for preventing electrolytic corrosion in the bearings thereof, comprising:

a stator having means for being grounded;

a rotor having a shaft, in said stator;

a bearing rotatively supporting said shaft;

an electrically conductive end cover mounted on said stator so as to surround said bearing; and

a centrifugal contact point mounted on said shaft, said contact point being responsive to rotation of said shaft so as to be in contact with said end cover when said shaft is standing still or rotating at low speeds to short-circuit said shaft and said end cover, and separated from said end cover to break the short-circuited condition as the speed of rotation of said shaft increases.

2. A rotary electric machine according to claim 1, wherein said shaft has a protrusion formed thereon and said centrifugal contact point comprises a resilient metal member having one end fastened to said protrusion and the other end bent to come into contact with said end cover.

3. A rotary electric machine according to claim 1, wherein said shaft has a recess formed at an end thereof and said centrifugal contact point comprises:

a contactor which is mounted on a peripheral surface of said recessed portion in said recessed portion, said contractor having a spring so as to be displaced in the radial direction of said shaft due to centrifugal force in response to rotation of said shaft to overcome the force of said spring as the speed of rotation of said shaft increases.