JPH0626227U - Magnetic shield transformer - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a magnetic shield transformer in which electromagnetic noise is reduced without degrading the DC superposition characteristics. [Structure] A drum-type ferrite core with integrated terminals is wound, and a pot-type ferrite core is covered with an air gap above the drum-type ferrite core, and a pot-type ferrite core is placed at the base of the drum-type ferrite core. In the magnetic shield transformer in which the opening edge of the core is placed, the placement section is configured so as to have no void except at least the lead lead section when viewed from the outer periphery.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic shield transformer such as a transformer of a DC-DC converter circuit and a choke coil.

[0002]

[Prior art]

 Conventionally, as for transformers, choke coils, etc. of DC-DC converter circuits, as shown in Fig. 6, a drum-type ferrite core 2 with an integrated terminal 1 is provided with windings 3, and the outer periphery of this drum-type ferrite core is cylindrical. There is known a structure in which the ferrite core 4 is wrapped, but since a direct current is superposed, a gap G is provided so that the superposition characteristic is not deteriorated.

[0003]

[Problems to be solved by the device]

 However, because of the air gap G, the leakage magnetic flux is large, and electromagnetic noise is generated in the DC-DC converter circuit. Therefore, countermeasures against this noise are an issue. This invention intends to provide a magnetic shield transformer in which electromagnetic noise is reduced without degrading the DC superposition characteristic.

[0004]

[Means for Solving the Problems]

 In order to solve the above problems, winding is applied to a drum-type ferrite core with integrated terminals, and the pot-type ferrite core is covered with an air gap above this drum-type ferrite core. In a magnetic shield transformer in which the opening edge of a pot-type ferrite core is placed on the part, the placement part is configured so as to have no void except at least the lead lead-out portion when viewed from the outer periphery. It is advisable to adopt a configuration in which the means for eliminating the above is a stepped portion or groove provided in the base portion or the pot portion.

[0005]

By doing so, the leakage magnetic flux from the side as well as the upper surface can be extremely reduced. The step or groove makes it easier to position the pot-type ferrite core when it is bonded, and reduces the variation in inductance.

[0006]

【Example】

 FIG. 1 is a sectional view of the essential parts of a first embodiment of the magnetic shield transformer of the present invention. A winding 3 is wound around a drum type ferrite core 2 in which the terminals 1 are integrated, and a step portion 8 to which an opening edge 7 of a pot type ferrite core 6 is fitted is provided in a lower base portion 5. The pot type ferrite core 6 has required gaps G1 and G2 arranged between the flange portion 2a and the ceiling portion 6a of the drum type ferrite core 2 and between the outer diameter and the inner diameter 6b of the collar portion 2a, respectively. The DC superposition characteristics are not deteriorated. In the figure, 2b is a lead-out groove for connecting the terminal 3a of the winding 3 to the terminal 1.

By doing so, the placing portion 78 including the opening edge 7 and the step portion 8 does not have a void when viewed from the side.

FIG. 2 shows an embodiment in which a groove 9 is provided instead of the stepped portion 8, but even in this case, there is no void when viewed from the outer periphery. 3, 4, and 5 show comparative data between the conventional product and the first embodiment of the present invention. The step or groove may be provided in the pot type ferrite core.

[0009]

[Effect of device]

 Since this invention is configured as described above, the leakage magnetic flux is reduced, and the electromagnetic noise can be remarkably reduced as in the above comparison data. Moreover, the direct current superimposition characteristics are not deteriorated by the internal air gaps G1 and G2, and the stepped portion and the groove also have the effect of serving as a mounting guide for the pot type ferrite core. Is constant, the variation in inductance is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a first embodiment of a magnetic shield transformer of the present invention.

FIG. 2 is a cross-sectional view of a main part of the second embodiment.

FIG. 3 is a graph showing leakage magnetic flux from the upper surface in comparison data of the conventional example and the first example.

FIG. 4 is a graph showing leakage flux from below with the same data.

FIG. 5 is a graph showing leakage flux from the groove direction with the same data.

FIG. 6 is a sectional view of a main part of a conventional magnetic shield transformer.

[Explanation of symbols]

 1 Terminal 2 Drum Type Ferrite Core 3 Winding 5 Base Part 6 Pot Type Ferrite Core G1 Gap G2 Gap 7 Opening Edge 8 Step 9 Groove

Claims (2)

[Scope of utility model registration request] 1. A drum-type ferrite core integrated with terminals is wound, a pot-type ferrite core is covered with an air gap above the drum-type ferrite core, and a pot is formed at the base of the drum-type ferrite core. In the magnetic shield transformer that has the opening edge of the type ferrite core,
A magnetic shield transformer characterized in that the mounting portion is configured so as not to have a void except at least the lead lead portion when viewed from the outer periphery. 2. The magnetic shield transformer according to claim 1, wherein the means for preventing the formation of voids when viewed from the outer periphery is a step portion or a groove arranged in the base portion or the pot portion.