Devices, systems, and methods for relieving stress

• US 7,764,038 B2
• Filed: 11/26/2007
• Issued: 07/27/2010
• Est. Priority Date: 04/26/2007
• Status: Expired due to Fees

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Finley, William, Ernst, Joerg, Obermeyer, Jason, Kikaganeshwala, Yagnesh
• Primary Examiner(s): Ro; Bentsu
• Assistant Examiner(s): DINH, THAI T
• Application Number:
  US11/944,948
• Publication Number:
  US 20080265696A1
• Time in Patent Office: 974 Days
• Field of Search: 318/114, 318/450, 318/451, 318/460, 318/488, 318/490, 735/70, 735/79, 735/82, 736/62, 736/63, 736/67, 738/625.9
• US Class Current: 318/490
• CPC Class Codes: H02K 15/02 of stator or rotor bodies
• CPC Class Codes: H02K 5/24 specially adapted for suppression or reduction of noise or vibrations

Abstract

Certain exemplary embodiments comprise a method that can comprise, via a device that originates sub-harmonic vibrations, applying a vibration treatment, to a rotor of an electric motor for a predetermined time period. The rotor can be thermally sensitive. The vibration treatment can be adapted to reduce internal stresses in the rotor, thereby reducing a vibration level of the rotor.

Claims

1. A method comprising:

via a device that originates sub-harmonic vibrations, said device directly attached to a first end of a rotor of an electric motor, applying a first vibration treatment, at a first predetermined sub-harmonic frequency, to said first end of said rotor of said electric motor for a first predetermined time period, said rotor thermally sensitive, said first predetermined sub-harmonic frequency determined based upon a measured first harmonic or resonance frequency, laminations of said rotor strapped to prevent flaring, a shaft and a core of said rotor not coupled via a key, said first vibration treatment adapted to reduce internal stresses in said rotor, thereby reducing a vibration level of said rotor.

2. The method of claim 1, further comprising:

applying a second vibration treatment applied to a second end of said rotor, said second vibration treatment at a second determined sub-harmonic frequency.

3. The method of claim 1, further comprising:

measuring a roundness of said rotor, said roundness indicative of a shape of said rotor.

4. The method of claim 1, further comprising:

prior to said first vibration treatment, removing said key.

5. The method of claim 1, further comprising:

prior to said first vibration treatment, mounting said rotor on two V-blocks, each V-block positioned on an inboard side of a shaft bearing mounting location of said rotor.

6. The method of claim 1, further comprising:

placing said device that originates sub-harmonic vibrations on said first end of said rotor.

7. The method of claim 1, further comprising:

determining that said first harmonic vibration frequency of said rotor is between approximately 35 Hertz and approximately 95 Hertz as a precondition to said first vibration treatment.

8. The method of claim 1, further comprising:

determining said first sub-harmonic vibration frequency.

9. The method of claim 1, further comprising:

determining a harmonic vibration frequency of said first end of said rotor, and

determining said first sub-harmonic vibration frequency based upon said harmonic vibration frequency.

10. The method of claim 1, further comprising:

determining a first harmonic vibration frequency of said first end of said rotor

determining a second harmonic vibration frequency of said first end of said rotor;

determining a second sub-harmonic vibration frequency based upon said second harmonic frequency; and

applying a second vibration treatment at said second determined sub-harmonic vibration frequency for a second predetermined time period.

11. The method of claim 1, further comprising:

determining a first harmonic vibration frequency of said first end of said rotor

determining a second harmonic vibration frequency of said first end of said rotor; and

applying a second vibration treatment at a second determined sub-harmonic vibration frequency for a second predetermined time period if a difference between said first harmonic vibration frequency and said second harmonic vibration frequency is greater than approximately 2 Hertz.

12. The method of claim 1, further comprising:

placing said device that originates sub-harmonic vibrations on a second end of said rotor.

13. The method of claim 1, further comprising:

placing said device that originates sub-harmonic vibrations on a second end of said rotor; and

determining a harmonic vibration frequency of said second end of said rotor;

determining a second sub-harmonic vibration frequency based upon said harmonic vibration frequency of said second end of said rotor, and

applying a second vibration treatment, at a second determined sub-harmonic frequency, to said second end of said rotor of said electric motor for a second predetermined time period.

14. The method of claim 1, further comprising:

determining a first harmonic vibration frequency of a second end of said rotor

determining a second harmonic vibration frequency of said second end of said rotor;

determining a second sub-harmonic vibration frequency based upon said second harmonic vibration frequency; and

applying a second vibration treatment, at a second determined sub-harmonic frequency, to said second end of said rotor of said electric motor for a second predetermined time period.

15. The method of claim 1, further comprising:

determining a first harmonic vibration frequency of a second end of said rotor;

determining a second harmonic vibration frequency of said second end of said rotor;

determining a second sub-harmonic vibration frequency based upon said second harmonic vibration frequency; and

applying a second vibration treatment at said second determined sub-harmonic vibration frequency if a difference between said first harmonic vibration frequency and said second harmonic vibration frequency is greater than approximately 2 Hertz.

16. The method of claim 1, further comprising:

installing said key between said shaft and said core.

17. The method of claim 1, further comprising:

axially attaching said core to said shaft at one end.

18. The method of claim 1, further comprising:

axially attaching said core to said shaft at one end; and

machining said rotor such that a measure of roundness of said rotor is within a predetermined range.

19. A method comprising:

reducing a measured vibration level of an electric motor rotor via a vibration treatment applied at a determined sub-harmonic frequency to a first end of said rotor for a predetermined time period by a device that originates sub-harmonic vibrations, said device directly attached to an end of said rotor of said electric motor, laminations of said rotor strapped, during said treatment, to prevent flaring, a shaft and a core of said rotor not coupled via a key during said treatment.