JPH01316911A - Transformer - Google Patents

Abstract

PURPOSE:To obtain a transformer, which can be easily complied with a requested difference between insulation distances, by a method wherein a protruding strip is provided in a circumferential direction on the outer peripheral surface of a oil bobbin, a winding space is axially splited by the protruding strip and the protruding strip is provided with a cut. CONSTITUTION:A partially cut circumferential protruding strip 14 is formed integrally with a central drum part 10 at a position closer to one end of the drum part 10. The protruding strip 14 is provided with a cut. Coils 21 and 22 are wound on a coil bobbin 1 by a lap winding. The coil 22 on the side of the internal layer is wound on a place between a padding part 11 on one side of the drum part 10 and the protruding string 14. When an insulation distance to be requested is short, the coil 22 is wounded on both sides of the protruding strip 14 through the cut of the protruding strip. Thereby, a transformer, which can be easily complied with a difference between insulation distances to be requested as well, is obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a transformer, particularly an input/output MJi type transformer used in a small output AC-DC converter such as a charger.

[Conventional technology]

As shown in FIG. 4, this type of transformer has coils 21 and 22 wound in parts around a coil bobbin 1, and as shown in FIG. However, with split winding, the coupling coefficient between the primary coil 21 and the secondary filter 22 is poor, and a spike voltage is generated on the primary side due to leakage magnetic flux, resulting in a high withstand voltage. A switching element is required, and a snubber circuit is required to absorb the heat, and the snubber circuit generates a large amount of heat, reducing the efficiency of the humputter. For this purpose, in general, overlapping winding as shown in FIG. 5 is performed, and tapes 4 and 5 are wound on both sides of both coils 21 and 22 in order to ensure an insulating distance between the primary and secondary coils.

[Problem to be solved by the invention]

In this case, the tapes 4 and 5 must be wound, which increases the number of assembly steps. Instead of the tape 4 on the inner layer side, it is possible to fix the winding space by adding padding to the coil bobbin in advance, but in this case, it is possible to fix the winding space depending on the difference in insulation distance regulated by each country or region. , it is necessary to prepare several types of coil bobbins. The present invention has been devised in view of the above points, and its purpose is to facilitate insulation measures and to meet the essential requirements.
An object of the present invention is to provide a transformer that can easily respond to differences in insulation distance.

[Means to solve the problem]

The present invention, in which two types of coils are wound overlappingly on the outer circumferential surface of a coil bobbin, provides circumferential protrusions on the outer circumferential surface of the coil bobbin, and the protrusions extend the winding space of the coil on the inner layer in the axial direction. It is distinctive in that it is divided and has cuts in the protrusions. [Function] According to the present invention, since the position of the fill on the inner layer side can be determined by the protrusions, the required insulation distance can be secured without wrapping tape, and the insulation distance is small. If this is acceptable, inner layer coils can be wound on both sides of the protrusion through the cuts formed in the protrusion. [Embodiment] The present invention will be described below in detail based on the illustrated embodiment.The coil bobbin 1 of this transformer 1 has built-up parts 11 and 11 on both ends of the central body 10, as shown in FIG. 7 runno 12.12 is formed through the WI7 runno 12.12, and a plurality of terminals 19 are implanted in each of the WI7 runno 12.12, and a portion is cut off near one end of the central body 10. A circumferential protrusion 14 is integrally formed. A concave groove 15 is formed on one surface of the one built-up portion 11.
As shown in FIG. 3(b), a concave surface 16.16 that widens toward the end is formed on the facing surface of both the 7-run nos. slits 17 and a protrusion 18 located at the opening of the slit 17 are provided. When winding the coils 21 and 22 around the coil bobbin l, as is clear from FIG. Wind the coil 22 on the side. When the required insulation distance is short, as shown in Figure 1(b),
A fill 22 is placed on both sides of the protrusion 14 through the cut in the protrusion 14.
wind it. After this, insulating tape 3 is applied to the entire area between both 7 runnos 12.12, that is, both built-up parts 11.11 and the coil 21.
Then, the outer layer side coil 21 is wound, tape 5 as a spacer is wound on both sides of the coil 21, and insulating tape 3 is further wound. The lead wires of the fills 21 and 22 are connected to the terminals 19 through the grooves 15, the concave surfaces 16, and the slits 17. When wrapping the insulating tape 3, this prevents any bulges from forming due to the lead wire, and also makes it easier to secure the insulation distance between the lead wire and the core, which will be described later. It is. The slit 17 and projection 18 prevent the lead wire leading to the terminal 19 from shifting. As shown in Fig. 1(a), if both coils 21, 22 are shifted in the axial direction, the opposing area of both coils 21, 22 is reduced, so the stray capacitance is reduced, and the negative side is switched. This reduces the possibility that unintentional voltage changes that sometimes occur will be transmitted to the secondary side as noise. The direction in which the coil 21 is shifted is the direction in which the coil 21 is separated from the terminal 19 to which it is connected via the lead wire. This is because even a small transformer can improve safety. Coil bobbin 1 with coils 21 and 22 wound as above
As shown in Figure 2, after installing the core 7,
The core 7 is fixed by wrapping the tape 8. The total length of the coil bobbin 1 at the part where the tape 8 is wound is:
The core 7 is made shorter than the total length of the part where the terminal 19 is implanted.
The reason why the length is the same as that of the core 7 or slightly shorter than that of the core 7 is to ensure that the core 7 is fixed with the tape 8, and also because the tape 8 is wider than the core 7. This is to ensure an insulating creepage distance from other electronic components. The core 7 used here is a type called EE Cocoa in terms of form, but originally it was an E type core used for EI Cocoa, that is, the length of each leg was the same as that of a normal EE Cocoa. By using a pair of wires that are longer than those used for cocoa, it is possible to easily secure the insulation distance and make the wires thinner.

【Effect of the invention】

As described above, in the present invention, since the position of the coil on the inner layer side can be determined by the protrusion, the required insulation distance can be secured without wrapping tape, and the insulation distance is small. If both sides are suitable, a single coil bobbin can be used because the inner layer coil can be wound on both sides of the protrusion through the cut formed in the protrusion. Further, by increasing the number of protrusions on the coil bobbin, even more demands can be met.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are cross-sectional views of one embodiment of the present invention, Figures 2 (a) and (b) are a plan view and a front view of the same, and pIS3 figure (a
), (b), and (c) are a front view, a sectional view, and a bottom view of the same coil bobbin as above, FIG. 4 is a sectional view of a conventional example, and tJIJ5 is a sectional view of another conventional example. 21.21 indicates a protrusion, and 21.21 indicates a coil. Agent Patent attorney Ishi 1) Ai 71 Coil bobbin Figure 2 Figure 3 (C) ]z]7

Claims (1)

[Claims] (1) In a coil bobbin in which two types of coils are wound overlappingly on the outer circumferential surface of the coil bobbin, circumferential protrusions are provided on the outer circumferential surface of the coil bobbin to divide the winding space of the inner coil in the axial direction by the protrusions. , a transformer characterized by having a cut in the protrusion.