JP2008071996A - Inverter transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a copper loss by reducing the number of turns of a primary winding in a conventional narrow inverter transformer in which a primary winding and a secondary winding are aligned in a straight line without changing the cross-sectional area of the core. I couldn't.
SOLUTION: A lower core 30 having horizontal end portions 31 and 32, an upper core 40 having outer legs 41 and 42 at both ends, a primary bobbin 10 having a vertical through-hole 11, and a horizontal through-hole 21. Two secondary bobbins 20, a primary winding 1 wound around the primary bobbin 10, and two secondary windings 2 wound around the two secondary bobbins 20, respectively. The center leg 33 provided on the lower core 30 is inserted into the through hole 11 of the primary bobbin 10, and the horizontal end portions 31 and 32 of the lower core 30 are inserted into the through holes 21 of the first and second secondary bobbins 20, respectively. .
[Selection] Figure 1

Description

  The present invention relates to an inverter transformer used in an inverter circuit for lighting a discharge lamp, and more particularly to a configuration of a two-output type inverter transformer.

  A two-output type inverter transformer in which two outputs can be obtained by one transformer is used. Compared to using two single-output transformers, the mounting area is smaller, and the inverter can be made smaller and more advantageous in terms of cost. As such a conventional two-output type inverter transformer, there is a vertical type in which the central axis of the winding, that is, the winding axis is vertical as described in Patent Document 1, or a winding axis as disclosed in Patent Document 2. There are horizontal horizontal types.

The inverter transformer of Patent Document 2 has a pair of secondary windings arranged on both sides of a primary winding, and the primary winding and the secondary winding are separated by scissors and wound around a common bobbin. An I-shaped core passes through the bobbin winding shaft, and the centers of the windings of the primary winding and the secondary winding are located on the same straight line. As described above, the inverter transformer in which the primary winding and the secondary winding are arranged in a straight line has an advantage that the entire width is reduced and the inverter transformer can be mounted in an elongated space on the printed circuit board.
JP 2001-126937 A Japanese Utility Model Publication No. 7-22528

Heat generation due to the electrical resistance of the primary winding in the inverter transformer, that is, copper loss may be a problem. In order to reduce this copper loss, it is necessary to shorten the number of turns by shortening the primary winding. Now, the input voltage V _in, B _m the maximum magnetic flux _density, when the cross-sectional area of the core was S, the frequency is f, number of turns N ₁ of the primary winding are related as follows.
N ₁ ≧ V _in / (2B _m · S · f)
Therefore, it is sufficient to increase the cross-sectional area S of the core to reduce the number of turns N ₁ of the primary winding. However, the cross-sectional area S of the core passing through the center of the primary winding and the secondary winding in the structure of Patent Document 2 is the same, it was not possible to reduce the number of turns N ₁ of the primary winding.

The present invention relates to an inverter transformer in which a primary bobbin 10 with a winding axis in the vertical direction and a terminal attached at the bottom, two secondary bobbins 20 with a winding axis in the horizontal direction and a terminal attached at the bottom, and the primary bobbin 10 Primary winding 1 and secondary winding 2 wound around two secondary bobbins 20, respectively, with two secondary bobbins 20 and primary bobbin 10 being centered on primary bobbin 10. It is characterized by a configuration arranged in a straight line.
Further, according to the present invention, in such an inverter transformer, a lower core 30 having first and second horizontal end portions 31 and 32 extending horizontally in opposite directions and an outer portion protruding downward and abutted against the lower core 30 are provided. The upper core 40 having the legs 41 and 42 at both ends, the primary bobbin 10 having the winding shaft 12 with the vertical through-hole 11, and the first and second having the winding shaft 22 with the horizontal through-hole 21. A secondary bobbin 20, a primary winding 1 wound around a winding shaft 12 of a primary bobbin 10, and two secondary windings 2 wound around respective winding shafts 22 of two secondary bobbins 20. A central leg 33 projecting toward the other core is formed integrally with at least one of the upper core 40 or the lower core 30, and the central leg 33 is inserted into the through hole 11 of the winding shaft of the primary bobbin 10. The first and second horizontal end portions 31 and 32 of the lower core 30 are respectively inserted into the through holes 21 of the winding shafts of the first and second secondary bobbins 20. To.

  According to the present invention, it is possible to easily enlarge the cross-sectional area of the core where the primary winding is wound, and to reduce the number of turns of the primary winding. As a result, an inverter transformer with small copper loss and heat generation and a small overall width can be obtained. In addition, the bobbin structure is simpler than the integrated bobbin, and the automation of the winding is easy.

  FIG. 1 shows an embodiment of an inverter transformer according to the present invention. As is apparent from FIG. 2, the primary bobbin 10 has a winding shaft 12 having a through-hole 11 in the vertical direction, and a plurality of terminals 13 are attached to two opposing side surfaces at the bottom. Although omitted in FIG. 2, the primary winding 1 is wound around the winding shaft 12 and the lead wire is connected to the terminal 13. The winding axis of the primary winding 1 is in the vertical direction.

  The secondary bobbins 20 are symmetrically arranged on both sides of the primary bobbin 10, and the primary bobbin 10 and the two secondary bobbins 20 are in a line on a straight line. As shown in FIG. 2, each of the two secondary bobbins 20 has a winding shaft 22 having a horizontal through-hole 21, and a plurality of terminals 23 are attached to two opposing side surfaces at the bottom. Although omitted in FIG. 2, the secondary winding 2 is wound around the winding shaft 22 and the lead wire is connected to the terminal 23. The secondary winding 2 is divided and divided by a plurality of scissors 25, and its winding axis is in the horizontal direction.

  Reference numerals 30 and 40 denote a pair of cores which are faced up and down to form two closed magnetic paths. As shown in FIG. 3, the lower core 30 is integrally formed with horizontal end portions 31 and 32 extending horizontally in opposite directions and a central leg 33 protruding upward. Outer legs 41 and 42 projecting downward are provided at both ends of the upper core 40. The center leg 33 of the core 30 is inserted into the through hole 11 of the winding shaft 12 of the primary bobbin 10 as shown in FIG. 1, and the horizontal end portions 31 and 32 of the lower core 30 are the through holes of the winding shaft 22 of the secondary bobbin 20, respectively. Insert into 21. Then, the outer legs 41 and 42 of the upper core 40 are butted against the lower core 30 and fixed.

 The center leg 33 may be formed on the upper core 40, or may be provided separately on both the upper core 40 and the lower core 30. Further, as shown in FIG. 4, a protrusion 35 positioned between the primary bobbin 10 and the secondary bobbin 20 is formed on the lower core 30 or the upper core 40 so that the primary winding 1 and the secondary winding 2 are electromagnetically coupled. The degree may be adjusted.

Front sectional view showing an embodiment of the transformer of the present invention Disassembled perspective view of bobbin of the transformer Exploded perspective view of the core of the transformer Front sectional view showing another embodiment of the transformer of the present invention

Explanation of symbols

1 ... Primary winding 2 ... Secondary winding
10 ... Primary bobbin
20 ... Secondary bobbin
30 ... Lower core
31, 32, horizontal end
33 ... Center leg
40 ・ ・ ・ Upper core

Claims (4)

  A primary bobbin with a winding shaft in the vertical direction and a terminal attached at the bottom, two secondary bobbins with a winding shaft in the horizontal direction and a terminal at the bottom, a primary winding wound around the primary bobbin, two An inverter transformer comprising: a secondary winding wound around each of two secondary bobbins, wherein the two secondary bobbins and the primary bobbin are arranged in a straight line with the primary bobbin at the center.   A primary having a lower core having first and second horizontal ends extending horizontally in opposite directions, an upper core having outer legs abutted against the lower core at both ends, and a winding shaft with a vertical through hole A bobbin, first and second secondary bobbins having a winding shaft with a horizontal through hole, a primary winding wound around the winding shaft of the primary bobbin, and first and second secondary bobbins. Secondary windings wound around the respective winding shafts, and at least one of the upper core and the lower core is integrally formed with a central leg protruding toward the other core, and the central leg is formed on the primary bobbin. The inverter transformer of Claim 1 which inserted in the through-hole of the winding shaft, and inserted the 1st, 2nd horizontal end part of the lower core into the through-hole of the winding shaft of the 1st, 2nd secondary bobbin, respectively.   The inverter transformer according to claim 2, wherein the center leg is formed only on the lower core.   3. The inverter according to claim 2, wherein the lead wire of the primary winding is connected to the terminal attached to the two opposite side surfaces of the primary bobbin, and the lead wire of the secondary winding is connected to the terminal attached to the two opposite side surfaces of the secondary bobbin. Trance.

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