JP2004104109A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent an inner winding from loosening, to readily make an electrical connection to the corresponding terminal strip, and to provide stabilized electrical characteristics. <P>SOLUTION: The transformer comprises a rodlike ferrite core, the inner winding wound directly around the ferrite core, and an outer winding wound around the inner winding. The transformer comprises a fixture attached to the ferrite core. The end of the inner winding is fixed around the ferrite core by the fixture. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a transformer for generating a high-voltage pulse voltage required for a high-pressure discharge lamp starting device or the like.

As shown in Patent Document 1 and Patent Document 2, this type of transformer includes an inner winding wound directly on a rod-shaped ferrite core and an outer winding wound on the inner winding. The structure surrounded by the insulation shield is adopted. The insulation shield is molded with resin in such a way that the connection terminal with the external circuit is integrally held together with these windings, and before the resin molding, the inner winding and the outer winding become the connection terminals, respectively. It is necessary to make an electrical connection to the terminal piece in advance. For example, the inner winding is wound around the ferrite core at a frequency of 100 to 200 turns to form a primary winding of the transformer, and the outer winding is a secondary winding of 4 to 5 turns. A high voltage is generated across the wire.
JP 2002-2107050 A JP 2002-93635 A

In this transformer, while the number of turns of the inner winding is increased, a rectangular wire is used for the inner winding so as to reduce the size. However, since the flat wire itself is weak, it is wound around the ferrite core. In this case, the electrical connection with the terminal piece becomes difficult, and the electrical characteristics of the transformer may vary.

The present invention has been made in view of these disadvantages, and a main object is to provide a small transformer that is easy to manufacture and has stable electric characteristics.

The transformer according to the present invention includes a rod-shaped ferrite core, an inner winding wound directly around the ferrite core, and an outer winding wound around the inner winding. The inner winding is an insulated flat wire having a rectangular cross section, and is tightly wound around the ferrite core such that the length of the rectangular cross section is perpendicular to the axis of the ferrite core. A feature of the present invention is that a fixture for fixing the end portion of the inner winding around the ferrite core is attached to the ferrite core, and thus unwinding of the inner winding is surely prevented. The electrical connection to the corresponding terminal piece is easy, and stable electrical characteristics can be provided.

It is preferable that the fixture is an insulating resin cap. This fixture has an opening larger than the end face of the ferrite core, and a plurality of protrusions protruding into the opening from the periphery of the opening abut against the peripheral surface of the end of the ferrite core, thereby fixing the cap to the ferrite core. There is an advantage that it can be easily attached to the ferrite core with one touch.

Further, it is desirable that the cap is formed in a flat plate shape having elasticity, and a slit that makes the size of the opening variable by elastic deformation of the cap is formed in the peripheral portion of the opening. As a result, the cap is provided with a large elastic deformability and can be easily attached to the ferrite core. Furthermore, when the cap is formed with a notch for holding the end of the outer winding, the unwinding of the outer winding can be prevented by one cap.
The transformer of the present invention includes an inner shield, an outer winding, and an insulating shield that surrounds the ferrite core. The above cap is designed to be embedded in the insulation shield so that it can be used for positioning the ferrite core in the mold that forms the insulation shield. It can be formed around the wire, and the reliability of the electrical characteristics of the transformer can be improved.

The fixture is preferably composed of a pair of caps that are fitted to both ends of the ferrite core and a connecting arm that couples both caps. In this case, between the caps located at both ends of the ferrite core in the axial direction. By sandwiching the inner winding at, both the winding start end portion and the winding end portion are held at fixed positions around the ferrite core.

The ferrite core preferably has a cross-sectional shape surrounded by two parallel straight lines and two arc-shaped curves, and the connecting arm is outside the arc-shaped curve portion and extends in the axial direction of the ferrite core. If it extends along, the thickness of the transformer defined between the parallel straight lines can be reduced. Further, by providing the connecting arm with a guide groove that defines the winding direction of the outer winding, it is possible to easily wind the outer winding. Furthermore, if the notch for holding the end of the outer winding is provided in the connecting arm, the outer winding can be prevented from unwinding before the insulation shield is molded.

Furthermore, if a terminal piece for winding and holding either end of the inner winding or the outer winding is formed on the connecting arm, a connection terminal with an external circuit can be easily connected to the winding on the connecting arm. Can be connected.

It is preferable that the above-mentioned fixing tool includes a terminal that can be fitted into the ferrite core by being fitted in a groove formed at the end of the ferrite core and that holds the end of the inner winding. It is also preferable that the fixture is made of a magnetic material or a conductive material.

Also, the fixture can be constituted by a holding portion that holds the end of the inner winding, and a leg piece that is sandwiched between the ferrite core and the inner winding wound on the ferrite core. In this case, the leg piece is stored in a recess formed at the end of the ferrite core.

Furthermore, with the upper surface of the leg piece receiving the inner winding as an inclined surface, the length in the radial direction from the outer surface of the ferrite core gradually increases from one end in the axial direction of the ferrite core to which the leg piece is attached to the center. In this way, the fixture is firmly fixed to the ferrite core by the inner winding, and even when an external force is applied to push the fixture out of the ferrite core in the axial direction during molding of the insulation shield, the fixture is surely ferrite. Can be held on the core.

Also, the fixture can be provided with a terminal for holding the inner winding drawn from the outer periphery of the ferrite core. In this case, the fixture is formed of an electrical insulator, and the fixture is provided in a state where the terminal is insulated from the ferrite core.

As the above-mentioned fixing tool, one having a plurality of leg pieces is preferable, and these leg pieces are sandwiched between the inner windings at a plurality of locations on the outer periphery of the end of the ferrite core.

As another means for fixing the end of the inner winding to the ferrite core, a notch may be formed in the axial end of the ferrite core. This notch forms a flange between the axial end of the ferrite core, and the end of the inner winding wound around the notch is pressed against the flange, so that the end of the inner winding is Fixed around. In this case, it is desirable that the bottom surface of the notch is deepened from the center of the ferrite core to the end surface along the axial direction of the ferrite core to minimize the step appearing on the outer periphery of the inner winding near the notch.

In the transformer of the present invention, since the fixing tool for fixing the end portion of the inner winding around the ferrite core is attached to the ferrite core, unwinding of the inner winding can be surely prevented, and correspondingly The electrical connection to the terminal piece is easy, and the effects of providing stable electrical characteristics can be achieved.

The transformer according to the present invention is designed as an optimum pulse transformer used to give a starting voltage to a discharge lamp used as a headlamp of an automobile. As shown in FIG. The coil block 20 in which the inner and outer windings 30 and 40 are wound around the core 10 is covered with an insulating shield 50 as shown in FIG.

The inner winding 30 is a so-called flat wire in which the periphery of the ribbon conductor is surrounded by an insulation coating such as polyimide resin, and is wound edgewise directly around the rod-shaped ferrite core 10, that is, FIG. As shown in FIG. 4, the cross-sectional length intersects with the axis of the ferrite core 10 so that the outer periphery of the ferrite core 10 is tightly wound, for example, with 200 turns, and the transformer secondary winding is A high voltage is generated at both ends.

The outer winding 40 is formed by coating a periphery of a normal round conductor 41 with an insulating coating 42 such as a fluororesin, and is wound on the inner winding 30 by, for example, five turns, As a primary winding, for example, a voltage of about 800 V is applied to generate a high voltage of 10 to 20 kV at both ends of the secondary winding.

The insulation shield 50 surrounds the coil block 20 by injection molding of a thermosetting resin such as unsaturated polyester mixed with a filler, and is connected to both ends of the inner winding 30 and the outer winding 40. The output terminal and the input terminal are held by the insulating shield 50 by simultaneous molding.

As shown in FIGS. 2 to 4, the outer winding 40 has a gap 48 between the winding start end portion 46 and the winding end portion 47 that increases the gap between the insulating coatings 42, and a gap 48 between adjacent windings. It is wound around the outer periphery of the inner winding 30 in the form to be formed. The length L of the gap 48 along the axial direction of the ferrite core 10 is set to 10 μm or more. Due to the presence of the gap 48, the resin can flow into the gap between the outer winding 40 and the inner winding 30 during the injection molding of the insulation shield 50, and between the windings 30, 40, Stable operating characteristics can be ensured without leaving any inconvenience in the operating characteristics. In order to keep the outer winding 40 wound around the outer periphery of the inner winding 30 until the insulation shield 50 is molded, the outer winding 40 is connected via a tape 60 coated with an adhesive or adhesive material. It is wound around the inner winding 30.

The winding start end portion 46 and the winding end portion 47 are each tightly wound around the insulation coatings 42 for about 1 to 2 turns to suppress unwinding. However, if the number of turns is small, the winding start end portion and the winding end portion 47 are wound. Between the outer winding 40 and the inner winding 30 at the end portion, the resin flows from the gap 48 provided in the center, and the space can be reliably filled with the resin. If the insulating coating 42 of the outer winding 40 is made of a fluororesin having a self-bonding property, unwinding at the winding start end or winding end can be prevented by tightly winding. Note that a gap 48 may be provided between adjacent windings at the winding start end and winding end. Instead of the tape 60 described above, a heat-sealing material may be applied around the inner winding, and the outer winding may be wound thereon in a heated atmosphere. In addition, the insulation coating of at least one of the inner winding 30 and the outer winding 40 is formed of a material exhibiting heat fusion, and the outer winding is placed on the inner side before the insulation shield 50 is molded. It is also possible to hold around the winding.

As shown in FIGS. 5 and 6, the insulation shield 50 is injection-molded so as to cover the coil block 20 with the coil block 20 held on the conductor frame 70, and is formed on the conductor frame 70. The output terminals 71 and 72 and the input terminals 73 and 74 are partially embedded in the insulating shield 50 and finally separated from the conductor frame 70. Each terminal 71 to 74 includes a holding portion to which both ends of the inner winding 30 and the outer winding 40 are connected.

As shown in FIGS. 1 and 7, a cap 90 that is attached to the axial end of the ferrite core 10 is used as a fixture for preventing the inner winding 30 from being unwound. 30 unwinding is suppressed. The cap 90 is formed by forming an opening 92 corresponding to the cross section of the ferrite core 10 on a plate made of an insulating resin, and a protrusion 93 protruding from the inner peripheral edge of the opening 92 is formed as shown in FIG. The cap 90 is held by the ferrite core 10 by being brought into contact with the outer periphery of the inner wire 30, and the inner winding 30 is pressed toward the center in the axial direction at the peripheral edge of the opening 92, thereby preventing the inner winding 30 from being unwound. The cap 90 is formed in a rectangular shape and conforms to the inner diameter of the mold that forms the insulation shield 50. The cap 90 can position the coil block 20 in the mold, and the coil block is accurately separated from the insulation shield 50. Can be coated. In the drawing, an example in which the cap 90 is used at one end of the ferrite core 10 in the axial direction is shown, but the cap 90 can be used at both ends of the ferrite core 10 in the axial direction. In addition, as shown in FIG. 9, a slit 94 can be provided in the cap 90 in order to facilitate the fitting of the ferrite core 10 into the opening 92. Furthermore, as shown in the figure, by providing a notch 96 that holds the end of the outer winding 40, unwinding of the outer winding can be suppressed.

FIG. 10 shows another example of a fixture that holds the end portion of the inner winding 30, and a pair of caps 90 </ b> A that are respectively attached to both end portions of the ferrite core 10 in the axial direction and a connecting arm 97 that couples them. Unwinding is prevented by pressing the end of the inner winding 30 with each cap 90A. Further, the connecting arm 97 forms a gap between the inner winding 30 and the outer winding 40 so as to guarantee a resin flow when the insulating shield 50 is molded. Further, the winding direction of the outer winding 40 can be easily determined by the guide groove 98 formed in the connecting arm 97. The cap 90A and the connecting arm 97 are integrally formed of an insulating synthetic resin.

FIGS. 11 to 13 show various modifications of the same fixing device. A pair of caps 90A to be attached to both ends of the ferrite core is a rectangle that fits the inner dimension of the molding mold of the insulation shield. A notch 96 that holds the end of the outer winding is formed in the connecting arm 97 of the cap 90A, or a metal piece 99 that is connected to the end of the outer winding and forms the input terminal is embedded. The configuration is shown. Although not shown, it is possible to integrally form a terminal piece as a terminal for the inner winding on the connecting arm 97. In addition, the connecting arm may be provided with a notch for holding the inner winding.

FIG. 14 and FIG. 15 show an example in which a stopper 100 that engages with the groove 12 formed at the end of the ferrite core 10 is used as a fixture. The stopper 100 is formed of electromagnetic soft iron, which is the same magnetic material as the ferrite core 10. The stopper 100 is attached to the ferrite core 10 by engaging both leg pieces 101 with the groove 12, and presses the end of the inner winding 30. . This stopper 100 is magnetically coupled to the ferrite core 10 and can bend the direction of the magnetic flux passing through the ferrite core 10 in a direction orthogonal to the axial direction of the ferrite core. The electrical characteristics are improved by increasing the interlinkage magnetic flux. 15, a conductive metal terminal 102 is welded to one leg piece 101, and the inner winding 30 is fixed to the metal terminal 102. The metal terminal 102 is exposed to the outside of the insulating shield 50 and used as an input terminal, or is connected to another input terminal held by the insulating shield. The stoppers are respectively attached to both end portions of the ferrite core 10 in the axial direction, and may be formed of a synthetic resin. Thus, since the stopper 100 is fixed with respect to the axial direction of the ferrite core 10, even if the resin flows in the axial direction in the molding die of the insulation shield 50, the stopper 100 is held in a predetermined position, and the inner side Unwinding of the winding 30 is reliably suppressed.

FIGS. 16 and 17 show a coil block 20 used in a transformer according to the second embodiment of the present invention. In the fixing tool 110 arranged on the end surface of the ferrite core 10, the inner winding 30 is formed. Prevent unwinding. This fixture is composed of a holding portion 111 that presses the end of the inner winding 30 and a leg piece 112 extending from one end of the holding portion. By winding the inner winding 30 from above the leg piece 112, At the same time as fixing the fixing tool 110 to the end of the ferrite core 10, the end of the inner winding 30 is pressed by the holding portion 111, so that the end of the inner winding 30 is in a fixed position of the end of the ferrite core 10. To prevent unwinding. This fixture 110 is provided at both ends of the ferrite core in the axial direction.

FIG. 18 and FIG. 19 show how the above fixture is changed. The fixture 110 is formed of a conductive material to integrally form the terminal piece 114. This fixture has a leg piece 112 accommodated in a recess 14 provided at the end of the ferrite core 10. The thickness of the leg piece 112 is slightly larger than the depth of the recess 14, and as shown in FIG. 20, the leg piece 112 is surely pressed and fixed to the outer periphery of the ferrite core 10 by the inner winding 30. It has become. The holding portion 111 is provided with a U-shaped hook 113 to which one end of the inner winding 30 is electrically connected. The terminal piece 114 protrudes out of the insulating shield 50 and becomes an input terminal. In the fixture 110 shown in FIG. 18, the opening of the U-shaped hook 113 faces downward so as to hold the winding start end of the inner winding 30, but the fixture 110 for fixing the winding end is shown in FIG. As shown, the opening of the U-shaped hook 113 is directed upward. Also in the case of this fixture 110, the terminal piece 114 protrudes out of the insulating shield 50 to form an input terminal.

22 to 24, the leg piece 112 and the holding portion 111 of the fixture 110 are integrally formed of an insulating synthetic resin, and a U-shaped hook 113 and a terminal piece 114 formed of a conductive metal are provided here. I support it. By using the leg pieces 112 and the holding portions 111 as insulating materials, the insulating distance between both ends of the inner winding 30 to which a high voltage is applied can be made as large as possible. Further, as shown in FIG. 24, the leg piece 112 is inclined so that the distance from the axis of the ferrite core gradually increases toward the central portion in the axial direction of the ferrite core 10. As a result, a wedge action is generated on the inner winding 30 wound around the ferrite core 10, and the fixing tool 110 can be prevented from coming off from the ferrite core 10.

25 shows an example in which a pair of leg pieces 112 are formed on the fixture 110. In the modification shown in FIG. In this case, a recess 14 is formed at the end of the ferrite core 10 so as to be continuous with the opposing upper and lower flat surfaces and the end surface, and the elastic deformation of the portion of the fixture 110 formed of synthetic resin including the leg pieces 112 is formed. The leg piece 112 is placed in the recess 14 so as to sandwich the upper and lower surfaces using the function. Thus, by utilizing the elastic deformability of the fixture 110, the fixture 110 can be easily and reliably held on the ferrite core 10, and the inner winding can be reliably prevented from unwinding.

In the modification shown in FIGS. 26 to 30, the pair of notches 16 formed at the axial ends of the ferrite core 10 hold the ends of the inner winding on the ferrite core to suppress unwinding. . The notches 16 are respectively formed in side arcs at the end portions in the axial direction, and flanges 18 are formed between the notches 16 and the end portions in the axial direction of the ferrite core 10. In addition, as shown in FIG. 27, the bottom surface of the notch 16 becomes deeper from the center in the axial direction of the ferrite core 10 toward the end surface, and the inner winding 30 is wound around the notch 16 and the flange 18 is wound around the flange 18. The end of the inner winding is held by the ferrite core 10 by pressing the end of the inner winding 30. The bottom surface of the notch 16 may be a straight line as seen from the end face of the ferrite core as shown in FIG. 29, or may be an arc shape along the arc portion as shown in FIG. In the latter case, the inner winding 30 captured in the notch 16 can be smoothly wound.

In the above embodiment, the coil block in which the outer winding is wound directly on the inner winding 30 or through a thin film is disclosed. However, the present invention is not necessarily limited to this. As shown in FIG. 31, the entire inner winding 30 may be housed in the insulating sleeve 120, and the outer winding may be wound around the outer periphery of the insulating sleeve 120. In this case, insulation between the inner and outer windings can be measured with the insulating sleeve 120, and an insulation coating for the outer winding that does not require a large pressure resistance can be used.

The disassembled perspective view which shows the internal structure of the trans | transformer which concerns on the 1st Embodiment of this invention. The perspective view which shows the external appearance of a trans | transformer same as the above. Sectional drawing of a transformer same as the above. The partial expanded sectional view of a transformer same as the above. The perspective view which shows the manufacturing process of a transformer same as the above. The perspective view which shows the manufacturing process of a transformer same as the above. The disassembled perspective view which shows the fixing tool used for a transformer same as the above. The end view which shows the attachment state of a fixing tool same as the above. The disassembled perspective view which shows the change aspect of the fixing tool used for a transformer same as the above. The disassembled perspective view which shows another aspect of the fixing tool used for a transformer same as the above. The perspective view which shows the various changes aspect of the fixing tool used for a transformer same as the above. The perspective view which shows the various changes aspect of the fixing tool used for a transformer same as the above. The perspective view which shows the various changes aspect of the fixing tool used for a transformer same as the above. The perspective view which shows the further another change aspect of the fixing tool used for a transformer same as the above. The perspective view which shows the further another change aspect of the fixing tool used for a transformer same as the above. The disassembled perspective view which shows the fixing tool used for the trans | transformer which concerns on the 2nd Embodiment of this invention. The perspective view which shows the state in which the fixing tool same as the above was attached. The perspective view which shows the other fixing tool applied to a transformer same as the above. The perspective view which shows the other fixing tool applied to a transformer same as the above. Sectional drawing which shows the attachment state of a fixing tool same as the above. The perspective view of the other fixing tool used for the same as the above. The perspective view which shows the other fixing tool applied to a transformer same as the above. The perspective view which shows the other fixing tool applied to a transformer same as the above. Sectional drawing which shows the attachment state of a fixing tool same as the above. The perspective view which shows the change aspect of a fixing tool same as the above. The perspective view which shows an example of the ferrite core used for a transformer same as the above. The partial top view of a ferrite core same as the above. The partial top view which shows the state which wound the coil | winding around the ferrite core same as the above. The end view of a ferrite core same as the above. The end elevation which shows the further another modification of a ferrite core same as the above. The perspective view which shows the coil block applicable to this invention.

Explanation of symbols

10 Ferrite Core 20 Coil Block 30 Inner Winding 40 Outer Winding 90, 100, 110 Fixing Tool

Claims (24)

A rod-shaped ferrite core;
An inner winding wound directly around the ferrite core;
An outer winding wound around the inner winding,
The inner winding is an insulated flat wire having a rectangular cross section, and the length of the rectangular cross section is tightly wound around the ferrite core in a form perpendicular to the axis of the ferrite core,
A transformer, wherein a fixing tool for fixing an end of the inner winding around the ferrite core is attached to the ferrite core. The fixing tool is a cap made of an insulating resin, and has an opening larger than the end face of the ferrite core, and a plurality of protrusions protruding into the opening from the periphery of the opening are in contact with the end peripheral face of the ferrite core. The transformer according to claim 1, wherein the cap is fixed to the ferrite core. 3. The transformer according to claim 2, wherein the cap is formed in a flat plate shape having elasticity, and a slit is formed at a peripheral portion of the opening so that a size of the opening can be changed by elastic deformation of the cap. . The transformer according to claim 3, wherein the cap is formed with a notch for holding an end of the outer winding. 3. The transformer according to claim 2, wherein the insulating shield surrounds the inner winding, the outer winding, and the ferrite core, and the cap is embedded in the insulating shield. The said fixing tool is comprised by a pair of cap fitted to the both ends of a ferrite core, and the connection arm which couple | bonds both caps, An inner side coil | winding is pinched | interposed between both caps. Transformer. The cross section of the ferrite core has a shape surrounded by two parallel straight lines and two arc-shaped curves, and the connecting arm extends along the axial direction of the ferrite core outside the arc-shaped curve portion. The transformer according to claim 6. The transformer according to claim 6, wherein a guide groove for defining a winding direction of the outer winding is formed in the connection arm. The transformer according to claim 6, wherein a cutout for holding an end of the outer winding is formed in the connecting arm. The transformer according to claim 6, wherein a terminal piece for winding and holding the end of the outer winding is formed on the connecting arm. The transformer according to claim 6, wherein a terminal piece for winding and holding the end of the outer winding is formed on the connecting arm. 2. The transformer according to claim 1, wherein the fixture is attached to the ferrite core by being fitted into a groove formed at an end of the ferrite core. The transformer according to claim 12, wherein the fixture is made of a magnetic material. The transformer according to claim 12, wherein the fixture includes a terminal for holding an end portion of the inner winding. The transformer according to claim 12, wherein the fixture is made of a conductive material. The said fixture is comprised by the holding | maintenance part which hold | maintains the edge part of an inner side winding, and the leg piece pinched | interposed between a ferrite core and the inner side winding wound on this. Transformer described in. The transformer according to claim 16, wherein a recess for accommodating the leg piece is formed at an end of the ferrite core. The upper surface of the leg piece that receives the inner winding is an inclined surface, and the length in the radial direction from the outer surface of the ferrite core gradually increases from one end in the axial direction of the ferrite core to which the leg piece is attached to the center. The transformer according to claim 16, wherein The transformer according to claim 1, wherein a terminal for holding an inner winding drawn from the outer periphery of the ferrite core is provided on the fixture. The transformer according to claim 16, wherein the fixture is provided with a terminal for holding an inner winding drawn from the outer periphery of the ferrite core. 2. The transformer according to claim 1, wherein the fixture is an electrical insulator, and an inner winding is electrically connected to a terminal of a conductor held by the fixture in a state insulated from the ferrite core. . The transformer according to claim 21, wherein the fixture includes a plurality of leg pieces, and the leg pieces are sandwiched between the inner windings at a plurality of locations on the outer periphery of the end portion of the ferrite core. A notch is formed near the axial end of the ferrite core, a flange is formed between the notch and the axial end surface of the ferrite core, and the end of the inner winding wound around the notch is The transformer according to claim 1, wherein the end of the inner winding is fixed around the ferrite core by being pressed against the flange. 24. The transformer according to claim 23, wherein the bottom surface of the notch becomes deeper from the center of the ferrite core toward the end surface along the axial direction of the ferrite core.

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