JPH07302720A - Transformer - Google Patents

Abstract

PURPOSE:To prevent temperature rise due to leakage flux, and improve efficiency, in an EE type transformer wherein a gap is formed in a central leg. CONSTITUTION:In a transformer wherein an EE type ferrite core 3 forming a gap 4 in a central leg 3a is fixed on a bobbin 2 around which a winding is formed, a protruding part 2a which prevents winding is arranged in the central part of the bobbin 2 which part corresponds with the gap part 4. Winding is not formed in the gap-corresponding part of the bobbin, so that heat generation is little. Since heat generation which is caused by leakage flux can be restrained, a transformer can be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an EE type transformer having a gap formed in a central leg thereof, which prevents temperature rise due to leakage flux and improves efficiency.

[0002]

2. Description of the Related Art As a conventional transformer with a gap,
There is a transformer in which an EE type ferrite core 3 is attached to a bobbin 2 having a winding 1 as shown in FIG. 3 with a gap 4 formed in a central leg 3a thereof.

This conventional transformer with a gap is EE
In the gap portion of the type ferrite core 3, since the magnetic permeability is extremely smaller than that of the core, a part of the magnetic flux sticks out of the core and swells as shown in the figure. Become. Therefore, in designing the transformer, even if the copper loss and the core loss are taken into consideration, there is a loss due to leakage and the temperature rise of the transformer becomes large, and there is a problem that miniaturization of the transformer cannot be achieved as designed. .

[0004]

SUMMARY OF THE INVENTION According to the present invention, an EE with a gap which suppresses a temperature rise due to a leakage magnetic flux and has a small loss is provided.
The purpose is to provide a type transformer. The present invention is also capable of realizing a small transformer for the purpose of designing EE.
The purpose is to provide a type transformer.

[0005]

According to the present invention, in a transformer in which an EE type ferrite core is mounted on a bobbin having a winding with a central leg formed with a gap, the center of the bobbin corresponding to the gap portion is provided. It is characterized in that a convex portion that obstructs the winding is provided in the portion.

[0006]

According to the transformer of the present invention, the convex portion for obstructing the winding is provided in the portion corresponding to the gap of the central leg of the EE type ferrite core of the bobbin, and the winding is not formed in this portion. The heat generated in the winding due to the leakage magnetic flux from the gap is reduced, and the loss is reduced.

[0007]

1 shows a transformer having a gap in the center leg of an EE type ferrite core which is an embodiment of the present invention. In addition, the reference numerals of the drawings are the same as those of FIG. In the illustrated transformer, 2 is a bobbin and winding 1
The EE type ferrite core 3 is attached to the central leg with a gap 4 formed therein. A collar-shaped convex portion 2 a is provided in the central portion of the bobbin 2 corresponding to the gap portion of the core 3. The convex portion 2a is formed integrally with the bobbin 2, and has a thickness larger than the gap 4 and occupying a strong leakage flux range. Since the convex portion 2a blocks the winding near the gap where the leakage magnetic flux is generated, the heat generation of the winding due to the leakage magnetic flux from the core is extremely small. Further, since the winding is multi-layered, the leakage magnetic flux in the vicinity of the convex portion on the outermost layer of the winding is extremely small. However, in order to reduce the loss, it is better not to provide the winding on the convex portion. The collar-shaped convex portion 2a may be provided with a split groove to allow the winding to pass therethrough.

FIG. 2 shows another embodiment of the present invention. The EE type ferrite core 3 is attached to the bobbin 2 having the winding 1 with a gap 4 formed at the center leg thereof. In this transformer, an insulating tape is wrapped around the center of the bobbin 2 corresponding to the gap 4 in a brim shape to form a convex portion 5 which is an obstacle to the winding. Since the convex portion 5 obstructs the winding, the heat generation of the winding due to the leakage flux from the core is extremely small. With this tape, there is an advantage that a convex portion can be formed at an arbitrary position on the bobbin with an arbitrary thickness.

In addition to the above, as the convex portion, a collar-shaped one can be attached at the time of winding.

In the above embodiment, a typical EE type core is taken as an example.
It goes without saying that this includes application to the same kind of core such as PQ.

[0011]

According to the present invention, since the winding is not provided near the gap part of the core, the heat generation of the transformer due to the leakage magnetic flux is small. Since the heat generation due to the leakage magnetic flux can be suppressed, the transformer can be downsized. Furthermore, since the convex portion is provided in the gap portion, the line capacitance between the windings can be reduced. Therefore, when used in a switching power supply, there is also an effect that the loss of the switching element due to the line capacitance can be reduced.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment showing a transformer of the present invention.

FIG. 2 is a front sectional view of another embodiment of the transformer of the present invention.

FIG. 3 is a front sectional view showing a conventional transformer.

[Explanation of symbols]

 1 coil 2 bobbin 2a convex part 3 EE type ferrite core 3a central leg 4 gap 5 convex part

Claims (3)

[Claims] 1. A transformer in which an EE type ferrite core is attached to a wound bobbin with a central leg having a gap formed therein, and a convex portion that obstructs the winding in the central portion of the bobbin corresponding to the gap portion. A transformer characterized by the provision of. 2. The transformer according to claim 1, wherein the convex portion that obstructs the winding is a middle collar of a bobbin. 3. The transformer according to claim 1, wherein the convex portion that obstructs the winding is a tape wound around the center of the bobbin corresponding to the gap portion.