Claims
- 1. A method of controlling the inductance in the output circuit of a D.C. electric arc welder operated over a given current range as a weld current is applied to a gap between an electrode and a workpiece, said method comprising:a) providing an inductor with a generally constant inductance over said current range for charging a capacitor connected in parallel with said gap; b) providing a choke having at least one winding, said choke having an inductance that gradually varies over said current range, said choke comprising a high permeability core having first and second pole pieces and an inductance controlling air gap, said air gap defined by end surfaces on said first and second pole pieces, said end surfaces being spaced from one another and facing one another, said end surfaces of said first and second pole pieces having corresponding inner and outer edges and a middle portion between said inner and outer edges, at least a portion of the middle portion of said corresponding end surfaces being spaced apart at a varying distance to vary the inductance of said choke over a current range, at least a portion of the middle portion of said end surfaces being spaced apart a distance greater than the distance between said inner and outer edges of said end surfaces; and, c) connecting said choke in series with said gap and between said gap and said capacitor.
- 2. The method as defined in claim 1, wherein said inductance of said choke varies generally inversely proportional to said weld current.
- 3. The method as defined in claim 2, wherein said inductance of said choke varies in a generally straight line to said weld current.
- 4. The method as defined in claim 2, wherein said inductance of said choke varies in curvilinearly to said weld current.
- 5. The method as defined in claim 1, including the step of directing a weld current of at least about 50 amperes through said winding and across said gap.
- 6. The method as defined in claim 1, wherein said middle portion of said corresponding end surfaces being spaced apart at a varying distance to substantially gradually vary the inductance of said choke over a current range, said inner and outer edge space selected to substantially prevent inflection points along the saturation curve of said choke.
- 7. The method as defined in claim 1, wherein each of said end surfaces has a cross-sectional shape, said cross-sectional shape of said end surfaces being symmetrical.
- 8. The method as defined in claim 1, wherein said air gap formed by said middle portions of said end surfaces is generally diamond shaped.
- 9. The method as defined in claim 1, wherein said air gap formed by said middle portions of said end surfaces is generally oval shaped.
- 10. The method as defined in claim 1, wherein at least a portion of said middle portion of at least one end surface includes a curvilinear surface portion.
- 11. The method as defined in claim 1, wherein at least one of said end surface of said first pole piece having a middle portion positioned between said inner and outer edges, said middle portion having substantially non-perpendicular oriented surfaces.
- 12. The method as defined in claim 1, wherein each of said end surfaces has a cross-sectional shape, said cross-sectional shape of said end surfaces being symmetrical.
- 13. The method as defined in claim 1, including the step of filling said air gap with a low permeability material.
- 14. The method as defined in claim 1, including the step of p roving a core and windings on said core of said choke to prevent saturation at a weld current of at least about 100 amperes.
- 15. A method of controlling the inductance in the output circuit of a D.C. electric arc welder operated over a given current range as a weld current is applied to a gap between an electrode and a workpiece, said method comprising:a) providing an inductor with a generally constant inductance over said current range for charging a capacitor; b) providing a choke having at least one winding, said choke having an inductance that gradually varies over said current range, said choke comprising a high permeability core having first and second pole pieces and an inductance controlling air gap, said air gap defined by an end surface on said first and second pole pieces, said end surfaces facing one another, said end surfaces of said first and second pole pieces having corresponding inner and outer edges, said end surfaces of said first and second pole pieces having a middle portion positioned between said inner and outer edges, at least a portion of the middle portion of said end surfaces being spaced apart a distance greater than the distance between said inner and outer edges of said end surfaces; and, c) connecting said choke in series with said gap and between said gap and said capacitor.
- 16. The method as defined in claim 15, wherein each of said end surfaces has a cross-sectional shape, said cross-sectional shape of said end surfaces being symmetrical.
- 17. The method as defined in claim 16, wherein at least a portion of said intermediate surface on at least one end surface includes a curvilinear surface portion.
- 18. The method defined in claim 15, wherein said air gap formed by said intermediate surfaces of said end surfaces is generally diamond shaped.
- 19. The method as defined in claim 15, wherein said air gap formed by said intermediate surfaces of said end surfaces is generally oval shaped.
- 20. The method as defined in claim 15, wherein at least a portion of said intermediate surface on at least one end surface includes a curvilinear surface portion.
- 21. The method as defined in claim 15, wherein said air gap is filled with a low permeability material.
- 22. The method as defined in claim 15, wherein said choke includes a winding for conducting welding current, said winding and said core are sized to prevent saturation at a weld current of at least about 100 amperes.
- 23. The method as defined in claim 15, wherein said end surfaces being spaced from one another.
- 24. The method as defined in claim 15, wherein said at least a portion of the middle portion of said corresponding end surfaces being spaced apart at a varying distance to substantially gradually vary the inductance of said choke over a current range.
- 25. The method as defined in claim 15, wherein said inner and outer edge spacing is selected to substantially prevent inflection points along the saturation curve of said choke.
- 26. The method as defined in claim 15, wherein said inner and outer edges of said end surfaces of said first and second pole pieces being spaced apart at generally the same distance.
- 27. The method as defined in claim 15, wherein said gap has a gradually converging width for at least a portion of the distance between said first and second ends of said two pole pieces.
Parent Case Info
This patent application is a continuation of application Ser. No. 09/534,583 filed on Mar. 27, 2000, pending, which is a continuation of application Ser. No. 09/184,149 filed on Nov. 2, 1998, now abandoned, and incorporated herein by reference.
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Continuations (2)
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Number |
Date |
Country |
Parent |
09/534583 |
Mar 2000 |
US |
Child |
09/563984 |
|
US |
Parent |
09/184149 |
Nov 1998 |
US |
Child |
09/534583 |
|
US |