Ground ring and enclosure in an electric motor

• US 9,917,491 B2
• Filed: 03/07/2014
• Issued: 03/13/2018
• Est. Priority Date: 03/07/2014
• Status: Active Grant

• Current Assignee: Nidec Motor Corporation (Nidec Corporation)
• Original Assignee: Nidec Motor Corporation (Nidec Corporation)
• Inventors: Northwall, Joel W., Theis, Kenneth R., Druhe, Timothy J., Lyle, David M.
• Primary Examiner(s): LEUNG, QUYEN PHAN
• Assistant Examiner(s): Johnson, Eric
• Application Number:
  US14/200,545
• Publication Number:
  US 20150256054A1
• Time in Patent Office: 1,467 Days
• Field of Search: 310 88
• CPC Class Codes: H01R 39/12 using bearing or shaft surface as contact surface
• CPC Class Codes: H01R 39/64 Devices for uninterrupted current collection
• CPC Class Codes: H02K 11/40 Structural association with grounding devices
• CPC Class Codes: H02K 2213/03 Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 5/136 explosion-proof
• CPC Class Codes: H02K 5/1732 radially supporting the rotary shaft at both ends of the rotor H02K5/1737 takes precedence

Abstract

An enclosure for a ground ring includes an enclosure housing configured to accept a ground ring and hold the ground ring in a predetermined position around a shaft that is electrically connected to a drive shaft of an electric motor. The ground ring having a first opening for the drive shaft and the enclosure housing has a second opening for the drive shaft. The enclosure includes an attachment configured to hold the enclosure housing around the shaft to dissipate an electrical charge and to form a cavity that contains the ground ring and includes a predetermined gap between a perimeter of the second opening of the enclosure and a surface of the drive shaft.

Claims

1. An enclosure housing and ground ring assembly comprising:

a ground ring having a single opening that is configured with a single diameter to enable a shaft to pass through the single opening;

an enclosure housing configured to receive the ground ring and hold the ground ring in a predetermined position around the shaft electrically connected to a drive shaft of an electric motor, the enclosure housing having a single opening with a single diameter that is aligned with the single opening in the ground ring, the single opening in the enclosure housing being configured to enable the shaft to pass through the enclosure housing and then through the single opening in the ground ring, the single diameter of the single opening in the enclosure housing being less than the single diameter of the single opening in the ground ring; and

a mounting member having a single opening that is aligned with the single opening in the ground ring and the single opening in the enclosure housing to enable the shaft to continue to pass through the single opening in the mounting member after the shaft has passed through the single opening in the enclosure housing and then through the single opening in the ground ring, the single opening in the mounting member having a single diameter that is less than the diameter of the single opening in the ground ring, the enclosure housing and the mounting member forming a cavity that contains the ground ring with a tight fit between the enclosure housing and the mounting member,

the cavity having a width that is parallel to a longitudinal axis of the shaft and that corresponds to a distance parallel to the longitudinal axis of the shaft that extends from an edge of the single opening of the enclosure housing that is most proximal to the ground ring to an edge of the opening of the mounting member that is most proximal to the ground ring, and

the enclosure housing forming a predetermined gap between a perimeter of the opening of the enclosure housing and a surface of the shaft that has a single height that corresponds to a difference between a diameter of the shaft and the single diameter of the opening of the enclosure housing along a length of the shaft from an axial position where a surface of the ground ring axially faces a surface of the enclosure housing to an edge of the single opening of the enclosure housing most distal from the ground ring, and

the mounting member has another predetermined gap between a perimeter of the opening in the mounting member and the surface of the shaft that has a single height that corresponds to a difference between a diameter of the shaft and the single diameter of the opening of the mounting member along another length of the shaft from an axial position where a surface of the ground ring axially faces a surface of the mounting member to an edge of the single opening of the mounting member most distal from the ground ring.

2. The assembly of claim 1, the mounting member being a bearing holder that engages an interior of a housing of the electric motor proximate to a bearing in the electric motor and an attachment is configured to attach the enclosure housing to the bearing holder.

3. The assembly of claim 2, wherein the other predetermined gap formed between the perimeter of the single opening of the mounting member and the surface of the shaft is approximately equal to the predetermined gap between the perimeter of the single opening in the enclosure housing and the surface of the shaft.

4. The assembly of claim 1, wherein the mounting member is formed in an exterior of a housing of the electric motor.

5. The assembly of claim 1 wherein the predetermined gap between the perimeter of the single opening of the enclosure housing and the surface of the shaft is approximately 0.009 inches.

6. The assembly of claim 1 wherein the predetermined gap between the perimeter of the single opening of the enclosure housing and the surface of the shaft is in a range of approximately 0.001 inches to 0.020 inches.

7. The assembly of claim 1 further comprising:

at least one brush formed from an electrically conductive material that is attached to the ground ring to provide a path for an electrical discharge from the shaft to the ground ring.

8. The assembly of claim 1, wherein the shaft is the drive shaft of the electric motor.

9. A ground ring assembly comprising:

a ground ring having a single opening that is configured with a single diameter to enable a shaft to pass through the single opening;

an enclosure housing configured to receive the ground ring and hold the ground ring in a predetermined position around the shaft, the shaft being connected to a drive shaft of an electric motor, the enclosure housing having a single opening that is aligned with the single opening in the ground ring that enables the shaft to pass through the single opening in the enclosure housing and then pass through the single opening in the ground ring, the single diameter of the single opening in the enclosure housing being less than the single diameter of the single opening in the ground ring; and

a bearing holder having a single opening that is aligned with the single opening in the ground ring and the single opening in the enclosure housing, the single opening in the bearing holder being configured to enable the shaft to continue to pass through the single opening in the bearing holder after the shaft has passed through the single opening in the enclosure housing and the single opening in the ground ring, the single opening in the bearing holder having a single diameter that is less than the single diameter of the single opening in the ground ring,

the enclosure housing being attached to the bearing holder to form a cavity that contains the ground ring, the cavity having a width that is parallel to a longitudinal axis of the shaft, that extends from an edge of the single opening of the enclosure housing that is most approximate to the ground ring to an edge of the opening in the bearing holder that is most approximate to the ground ring, the enclosure housing and the bearing holder having a tight fit,

the enclosure housing with a predetermined gap between a perimeter of the single opening of the enclosure housing and a surface of the shaft that has a single height that corresponds to a difference between a diameter of the shaft and the single diameter of the opening of the enclosure housing along a length of the shaft from an axial position where a surface of the ground ring axially faces a surface of the enclosure housing to an edge of the opening in the enclosure housing that is most distal to the ground ring, and

the bearing holder with another predetermined gap between a perimeter of the single opening in the bearing holder and the surface of the shaft that has a single height that corresponds to a difference between a diameter of the shaft and the single diameter of the opening of the bearing holder along another length of the shaft from an axial position where a surface of the ground ring axially faces a surface of the bearing holder to an edge of the single opening of the bearing holder most distal from the ground ring.

10. The ground ring assembly of claim 9 wherein the predetermined gap between the perimeter of the opening of the enclosure housing and the surface of the shaft is approximately 0.009 inches.

11. The ground ring assembly of claim 9 wherein the predetermined gap between the perimeter of the opening of the enclosure housing and the surface of the shaft is in a range of approximately 0.001 inches to 0.020 inches.

12. The ground ring assembly of claim 9 wherein the shaft is the drive shaft of the electric motor.