JPH11135332A - Variable inductance transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid increase in a volume and restrain cost by arranging a member for increasing elastic force in accordance with temperature rise at a junction part of a core in a transformer. SOLUTION: A transformer 1 has a hollow part and is constituted by a coil 4 wound on the outer circumference of a bobbin 3 having terminal pins 2, an E-shaped magnetic substance 5, an I-shaped magnetic substance 6, a member 7 such as a vulcanized rubber having a characteristic such as to increase the elastic force in accordance with temperature rise, and an elastic supporting metal fitting 8 for holding and fixing the magnetic substances 5 and 6 in a direction of close contact with each other. Also, two magnetic substances forming a core have the same E-shape, and an elastic member inserted in a center part of three junction parts of the magnetic substances is removed to form an air gap, that is, a cavity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer constituting a switching power supply, for example.

[0002]

2. Description of the Related Art Conventionally, in a general transformer used for a switching power supply, when a material of a magnetic material forming a core, a core size, a number of windings, and a gap interval are determined,
The inductance value is fixed and cannot be changed. In this case, as the output power increases, the current flowing in the coil of the transformer increases, and when the output power exceeds a certain value, the magnetic flux density of the core reaches a limit and the magnetic flux is saturated. As a result, the inductance value is extremely reduced to a value close to 0,
It has become impossible to obtain desired characteristics as a transformer.

Therefore, a transformer as shown in FIG. 5 has been proposed in Japanese Patent Application Laid-Open No. 6-267748. In the transformer 17 shown in FIG. 5, reference numerals 18 and 19 are magnetic bodies made of E-type and I-type ferrite, and form a core.
Reference numeral 20 denotes a winding. Reference numeral 21 denotes another independent magnetic component made of ferrite, which is sandwiched between the magnetic materials 18 and 19. Further, 22 is a winding of the magnetic component 21.

The transformer shown in FIG. 5 changes the magnetic resistance of the magnetic component 21 by controlling the current of the winding 22 to control the inductance value of the transformer constituted by 18, 19 and 20. . With this configuration,
With respect to an increase in output power, by reducing the inductance value to some extent, it is possible to increase the current limit value and prevent the core from reaching magnetic saturation.

[0005]

However, the conventional transformer 17 has the following problems.
That is, the volume of the transformer 17 is increased by the addition of the magnetic component 21. Therefore, the mounting volume is larger than that of a normal transformer, and the volume of the entire power supply unit is larger. Further, due to the restriction of the insulation distance of the safety standard, the distance between the magnetic component 21 and other components is ensured, so that the volume of the entire power supply unit is also increased.

If the magnetic component 21 is made thin in order to alleviate the above-mentioned problem, the following problem occurs. That is, the magnetic component 21 is liable to crack and break when a shock is applied during the step of manufacturing the transformer 17, the step of mounting the transformer 17 on the power supply unit, and the use of the power supply unit. The magnetic component 21 and the winding 22
The parts cost and the manufacturing cost of the transformer are large, which increases the cost of the transformer.

Accordingly, a first object of the present invention is to provide a transformer capable of obtaining a large output power while avoiding an increase in volume and at a low cost by a simple structure without largely changing the shape from a general transformer. Is to provide.

It is a second object of the present invention to provide a transformer in which the manufacturing cost of the core material is reduced.

Further, a third object of the present invention is to provide a transformer with a further reduced cost.

[0010]

Means for Solving the Problems To achieve the first object, the present invention firstly combines an E-type and an I-type magnetic material on the outer periphery of the hollow portion of a bobbin having a hollow portion. In a transformer having a core formed therein, a member that increases elastic force in accordance with a rise in temperature is disposed at a joint of the core.

In the above-described configuration, a transformer capable of obtaining a large output power can be obtained by a simple configuration without largely changing the shape from a general transformer, while avoiding an increase in volume and suppressing costs.

In order to achieve the second object, the present invention secondly forms a core by combining two E-shaped magnetic bodies having the same shape, and joins the three magnetic bodies at three locations. The structure is characterized in that members that increase the elastic force in accordance with a rise in temperature are inserted into the portion one by one.

According to the above configuration, a transformer having a reduced core material manufacturing cost can be obtained.

[0014] In order to achieve the third object, the present invention provides, in a third aspect, a core formed by combining the two E-shaped magnetic materials having the same shape, and forming three cores between the magnetic materials. In the joint portion, a member for increasing the elastic force in accordance with the temperature rise is not inserted into only one central portion, and a center air gap is provided.

In the above configuration, two elastic members may be interposed between the magnetic members by the provision of the air gap, so that the cost can be reduced by reducing the volume of the elastic member used.

[0016]

【Example】

(Embodiment 1) FIG. 1 is a sectional view showing a transformer according to Embodiment 1 of the present invention. Hereinafter, description will be made with reference to FIG. In FIG. 1, reference numeral 1 denotes a transformer, which is provided with a hollow portion and has a coil 4 wound around an outer periphery of a bobbin 3 having a terminal pin 2, and is provided with an E-type magnetic body 5, an I-type magnetic body 6, and a temperature rise. It comprises a member 7, such as a vulcanized rubber, having a characteristic of increasing the elastic force, and a supporting metal member 8 having an elastic force for holding and fixing the magnetic bodies 5 and 6 in a direction approaching each other. However, as shown in FIG. 2, the support fitting 8 has an elastic force (biasing force) in the direction of the arrow.

Here, as shown in FIG. 1, reference numerals 5 and 6 denote a magnetic material such as ferrite, and form a core, that is, a closed magnetic circuit together with a member 7 made of rubber or the like for securing a gap length G. If the gap length G is increased, the inductance value is reduced to some extent, the limit value of the current is increased, and the core can be prevented from reaching magnetic saturation in advance. That is, when the output power increases and the transformer 1 starts to move toward the direction of magnetic saturation, the temperature of the magnetic bodies 5 and 6 increases. At that time, the member 7 increases the elastic force according to the temperature rise. as a result,
The gap length G increases until the magnetic force of the member 7 and the elastic force (biasing force) of the support bracket 8 are balanced by pushing the magnetic members 5 and 6 away from each other, reducing the inductance value to some extent. In advance and automatically automatically.

The effect based on the first embodiment is that a transformer which can obtain a large output power while avoiding an increase in volume and at a reduced cost can be obtained by a simple configuration without largely changing the shape from a general transformer. That is.

FIG. 3 is a sectional view showing a transformer according to a second embodiment. In the second embodiment, the core shape of the transformer of the first embodiment is changed. The same parts as those in FIG. 1 are denoted by the same reference numerals. This will be described below with reference to FIG.

In FIG. 3, reference numeral 9 denotes a transformer;
And 11 are E-shaped magnetic bodies of the same shape, 12, 13
And 14 indicate elastic members.

The new effect of the transformer 9 of the second embodiment is that the two magnetic members 10 and 11 forming the core are both of the same E-shape, and one type of magnetic member can be manufactured. The point is that it can be suppressed.

(Embodiment 3) FIG. 4 is a sectional view showing a transformer according to Embodiment 3. In the third embodiment, the center of the core of the transformer of the second embodiment is formed as an air gap. In addition,
1 and 3 are denoted by the same reference numerals.
Hereinafter, description will be made with reference to FIG.

In FIG. 4, reference numeral 15 denotes a transformer,
Reference numeral 6 denotes an air gap. The performance of the transformer does not deteriorate even if the elastic member inserted at the center of the three joints between the magnetic bodies 10 and 11 is removed to form an air gap 16, that is, a cavity. In addition, two magnetic bodies 10 and 11
Of the three joints, elastic members 1
No. 2 and 13 are inserted, and no core displacement occurs.

The new effect of the transformer according to the third embodiment is that, since the air gap is provided, the number of the elastic members sandwiched between the magnetic members may be two, and the cost is reduced by the reduction in the volume of the elastic member used. Is that

[0025]

As described above, according to the present invention,
With a simple configuration without greatly changing the shape from a general transformer, it is possible to provide a transformer that can obtain a large output power while avoiding an increase in volume and suppressing costs.

Further, according to the present invention, it is possible to provide a transformer in which the cost of the core material is suppressed.

Further, according to the present invention, the number of the elastic members sandwiched between the magnetic members is sufficient for the provision of the air gap, so that the cost can be reduced because the volume of the elastic member used is reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a transformer according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating a support bracket of the transformer according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a transformer according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a transformer according to a third embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional transformer.

[Explanation of symbols]

 1, 9, 15, 17 Transformer 2 Terminal pin 3 Bobbin 4, 20, 22 Winding 5, 10, 11, 18 E-type magnetic body 6, 19 I-type magnetic body 7, 12, 13, 14 Elastic member 8 Support bracket 16 Air gap 21 Magnetic parts

Claims (5)

[Claims] 1. A transformer having a core formed by winding a coil around an outer periphery of a hollow portion of a bobbin having a hollow portion and combining two magnetic materials inside the hollow portion of the bobbin and the outer periphery of the coil. At the joint of the magnetic material,
A transformer characterized by disposing an elastic member that increases an elastic force according to a temperature rise. 2. The transformer according to claim 1, wherein said two magnetic members are made of E-type and I-type magnetic members, and said elastic member is one member disposed between said two magnetic members. A transformer characterized by that: 3. The transformer according to claim 1, wherein said two magnetic bodies are both E-shaped having the same shape, and said elastic member is provided at each of three joints between said two E-shaped magnetic bodies. A transformer characterized by being arranged one by one. 4. The transformer according to claim 3, wherein the elastic member is not inserted into only one central portion of the three joints between the two E-shaped magnetic bodies, and a center air gap is formed. A transformer characterized by that: 5. The transformer according to claim 1, further comprising a support fitting for supporting the two magnetic bodies, wherein the support fitting has a direction in which the sandwiched magnetic body is fastened. A transformer characterized by having power.