Inductive element construction, particularly fluorescent lamp ballast

• US 4,240,057 A
• Filed: 08/17/1979
• Issued: 12/16/1980
• Est. Priority Date: 08/19/1978
• Status: Expired due to Term

• Current Assignee: Vossloh-Schwabe GmbH
• Original Assignee: Firma Hermann Schwabe
• Inventors: Bachorz, Gunther, Decher, Friedrich
• Primary Examiner(s): Kozma, Thomas J.
• Application Number:
  US06/067,339
• Time in Patent Office: 487 Days
• Field of Search: 336/165, 336/178, 336/134, 336/212, 336/210, 336/214, 336/215, 336/233, 336/234
• US Class Current: 336/165
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 37/00 Fixed inductances not covered by group H01F17/00
• CPC Class Codes: H01F 38/10 Ballasts, e.g. for discharge lamps

Abstract

To permit adjustment of the air gap of an inductance unit suitable as a ballast for fluorescent lamps particularly in form of a leakage transformer or as a choke, for multi-voltage connection, an outer, essentially U-shaped core structure (1, 100), and having an integral connecting cross element (1, 101a), and two parallel leg elements (1b, 101b), has at least one longitudinally slidable cross element (2, 2'"'"', 2"; 3, 3'"'"'), the cross element being formed with a central longitudinal core element (14, 15; 14'"'"', 14") extending parallel to the leg elements, and short of the adjacent cross element, and longitudinally slidable within the leg elements so that the air gap between the longitudinal element and the adjacent cross element, and forming a magnetic shunt, can be adjusted after manufacture of the attached laminate to compensate for manufacturing tolerances and provide an inductance element having design impedance regardless of variation in the size of the longitudinal core element.

Claims

1. Inductive element construction, particularly for a fluorescent lamp ballast or transformer, comprising

an outer, essentially U-shaped core structure (1, 100) of one-piece construction having a connecting cross element (1a, 101a) and two parallel leg elements (1b, 101b);

a separate closing cross element (3, 3'"'"') positioned between the open ends of the parallel leg elements and in magnetically coupled engagement therewith, to form a closed outer magnetic circuit;

a separate central cross element (2, 2'"'"', 2") positioned between the parallel leg elements (1b, 101b) and located intermediate the connecting cross element (1a, 101a) and the closing cross element (3, 3'"'"');

central longitudinal core elements (14, 15, 14'"'"', 14") extending parallel to said leg elements (1b, 101b) and being located intermediate the longitudinal extend of said cross elements,

and electrical winding means (4,

     5) wound over one of said central core elements,

wherein, in accordance with the invention,

the central longitudinal core elements (14, 15, 14'"'"', 14") terminate short of engagement with at least one of the facing cross elements to form at least one air gap (6, 20,

     22) therewith,

at least one central longitudinal core element being integral with one of said separate cross elements, said one separate cross element being longitudinally slidably positionable with respect to an adjacent parallel leg element to permit adjustment of the width of the air gap;

and wherein the outer end face surfaces (7,

     9) of said separate core elements are in magnetically coupled engagement with the inner facing surfaces (8,

     10) of the parallel leg elements (1b, 101b) to form a contacting magnetic circuit therewith.

2. Construction according to claim 1, wherein the central core elements (14, 15, 14'"'"', 14") extend short of engagement with two facing cross elements to form two air gaps, and wherein the widths of the air gaps are different.

3. Construction according to claim 1, further comprising non-magnetic inserts (6, 21, 23) located in the air gaps to define the widths thereof.

4. Construction according to claim 3, wherein the thicknesses of the non-magnetic inserts are different.

5. Construction according to claim 3, wherein one of the non magnetic inserts comprises rigid material, and the other comprises a deformable material.

6. Construction according to claim 1, wherein (FIG. 2) the separate central cross element (2'"'"') and the longitudinal core element (14'"'"') are an integral unit of generally cross shape.

7. Construction according in claim 1, wherein (FIGS. 1 and 3) the separate central cross element (2) and the separate closing elements (3) each are integral with a longitudinal core element (14, 15) and each is of generally T-shape.

8. Construction according to claim 1, wherein the winding means comprises two windings (4, 5) wound about outer end portions of the separate central cros element (2, 2'"'"', 2") and separated from each other by the longitudinal core elements (14, 15, 14'"'"').

9. Construction according to claim 1, wherein the winding means (4, 5) comprises two windings wound about the central core element;

and wherein the cross section of the central core element in the region of one of the windings has an effective magnetic cross section which differs from that in the region of the other of the windings.