JPH11260659A - Transformer and molding die for transformer bobbin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability with relatively easy coping, without having to require changes of materials for molding a transformer bobbin to special types or large changes in manufacturing processes, and to provide the transformer which is not easily destroyed due to vibration or drop impact. SOLUTION: This transformer is constituted so as to be completed by assembling a magnetic material core 3. A plurality f terminals 9 are provided on a transformer bobbin for connecting the wiring electrically and mechanically by binding them up, so that at the same time, a transformer bobbin 4 that is formed integrally with grooves 7 between terminals 9 for passing wires is used. The transformer bobbin 4 is used which has no stress concentration region in the slits 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer and a molding die for a transformer bobbin, and more particularly to, for example, a transformer for a switching power supply comprising a transformer using a magnetic material core among transformers used for a power supply. The present invention relates to a technique that can be suitably applied.

[0002]

2. Description of the Related Art In general, a switching power supply has advantages that it is smaller and lighter than a dropper power supply and has a high conversion efficiency. I have.

[0003] For this reason, electronic and electric equipment configured with a built-in switching power supply can be reduced in size and weight, so that anyone can easily carry it, and the industrial contribution is measured. There is something unknown.

FIG. 7 is an external perspective view of a transformer generally used conventionally in a switching power supply device. FIG. 8 is a side view of the transformer shown in FIG.
In both figures, a transformer 100 is completed by assembling a magnetic core 103 on a transformer bobbin 105 on which a winding 108 is wound. In order to allow an electric wire drawn from the winding between terminals 9 to pass therethrough. Transbobbin 1 integrally forming groove 107 having a corner as shown in the figure
05 is used.

The electric wire drawn from the winding is wound around the terminal 9 inserted into the transformer bobbin 105 so as to be electrically and mechanically connected. By inserting and soldering the terminal into the mounting hole portion, it is used in a completed state as shown in FIG.

In FIG. 8, the shape of the groove 107 of the transformer bobbin 105 is formed such that the angle of the corner is substantially 90 degrees.

[0007] Devices equipped with a transformer configured as described above may be improperly handled during transportation,
Hook the power cord while using the adapter,
It is assumed that an excessive impact such as dropping from the desk is applied to the power supply device.

As a result, on the side of the power supply unit, an excessive impact is concentrated on a relatively heavy transformer among the components constituting the power supply unit, and as shown in FIG.
As a result of the occurrence of stress concentration at the corners of
07 occurs at the corner, and a transformer breakdown phenomenon occurs.

As a countermeasure against this, in order to improve the breaking strength of the trans bobbin conventionally, instead of the trans bobbin as shown in FIG. 10, a reinforcing portion 105a is formed at a corner which intersects at right angles as shown in FIG. We are taking measures for continuous molding.

Alternatively, for example, see JP-A-6-96965.
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 6-163278 and JP-A-6-163278, a method is adopted in which a transformer is put in an outer case that holds the entire transformer and fixed with resin.

[0011]

However, FIG.
According to the method of increasing the breaking strength of the transformer bobbin 105 by reinforcing measures as described in the above, the variation in the outer dimensional accuracy of the magnetic material core to be used is large, so that the magnetic core cannot be fixed properly, and the excessive impact such as dropping occurs. On the other hand, there is a problem that it is difficult to perform reinforcement with sufficient strength.

If the thickness of the trans bobbin is increased or the inclined portion of the reinforcing portion 105a is set large in order to obtain a trans bobbin having a sufficient strength, the effective window area of the transformer cannot be widened. For this reason, there is a problem that the performance of the magnetic material core cannot be sufficiently brought out.

[0013] A method using a high-strength resin for the molding material of the trans bobbin itself is also known (Japanese Patent Application Laid-Open No. Hei 7-300561). Materials that must be satisfied and satisfy all of them have the problem of being more expensive than conventional materials. Also, judging from the actual use in the market, there is a situation that new molding materials cannot be easily adopted because of the risks involved.

Further, according to the method disclosed in JP-A-6-96965 and JP-A-6-163278, in which a transformer is put in an outer case for holding the entire transformer and fixed with resin, the process is simplified. In addition to the extra cost required, the transformer becomes large and heavy, making it impossible to fully utilize the advantages of the switching power supply such as small size and light weight.

Accordingly, the present invention has been made in view of the above-described problems, and has been made without changing the molding material of the transformer bobbin to a special material and without significantly changing the manufacturing process. An object of the present invention is to provide a highly reliable transformer and a transformer bobbin molding die which can be easily dealt with and are not easily broken by vibration or drop impact.

[0016]

According to the present invention, there is provided a transformer completed by assembling a magnetic core to a transformer bobbin on which a winding is wound, in order to solve the above-mentioned problems and achieve the object. A plurality of terminals for electrically and mechanically connecting the windings including a method of winding are provided on the transformer bobbin, and a groove portion for passing an electric wire drawn from the windings between the terminals is integrally formed. A transformer using a transformer bobbin formed, wherein the transformer bobbin having no stress concentration portion in the groove is used.

Further, the present invention is characterized in that the groove portion is formed from a concave curved surface having no acute angle so that the transformer bobbin having no stress concentration portion is used.

Further, it is preferable that the groove is formed of a concave polyhedron composed of at least five planes in which an angle between adjacent surfaces is 90 degrees or more, so that the transformer bobbin having no stress concentration portion is used. Features.

Further, the present invention is characterized in that the trans bobbin continuously formed from the end so as to form the concave curved surface is used only at the bottom of the groove.

Further, the present invention is characterized in that the trans bobbin in which at least one groove is formed is used.

A transformer bobbin forming die for forming a transformer bobbin completed from a predetermined resin material by winding a winding and assembling a magnetic material core. A plurality of terminals for electrically and mechanically connecting windings are insert-molded in the transformer bobbin, and a shape having no stress concentration portion in a groove portion through which an electric wire drawn from the winding passes between the terminals. And a cavity piece having a cavity portion formed therein.

Further, the present invention is characterized in that it has the cavity piece formed of a concave curved surface having no acute angle, and after the insert molding, the trans bobbin is molded so as not to have the stress concentration portion.

The cavity bobbin is formed of a concave polyhedron composed of at least five planes having an angle of 90 ° or more between adjacent surfaces, and the trans bobbin has the stress concentration portion after the insert molding. It is characterized by being molded so as not to be formed.

In addition, the present invention is provided with the cavity piece continuously formed from the end so as to form the concave curved surface only at the bottom of the groove, so that the transformer bobbin does not have the stress concentration portion after the insert molding. It is characterized by being molded.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the accompanying drawings.

FIG. 1 is a side view of a transformer according to a first embodiment of the present invention. FIG. 2 is an enlarged view of a main part of a molding die showing a state in which a groove of the transformer bobbin 5 of FIG. 1 is molded. FIG. 3 is an external perspective view showing a state in which the transformer of FIG. 1 is mounted on a circuit board.

The transformer will be described with reference to FIGS. 1, 2 and 3. The transformer 1 is mounted on a printed circuit board 2 (hereinafter, referred to as a circuit board) on which the transformer 1 is mounted. The transformer 1 includes a pair of magnetic material cores 3,
This is completed by inserting and fixing the transformer bobbin 4 to the through hole shown by the broken line and the outer peripheral side. The pedestal portion 5 of the transformer bobbin 4 is integrally formed as described later. The pedestal portion 5 of the transformer bobbin 4 is formed with a groove 7 for drawing out a winding as shown in the figure. After passing the lead wire 6 from the winding portion 8 below the groove 7, It is configured so as to be wrapped around the terminal 9.

A copper pattern 10 is provided on the circuit board 2 for soldering the terminals 9 of the transformer 1.
The transformer 1 is fixed by a soldering portion 11. 3, an insulating tape 12 wound around the outside of the winding wound around the transformer bobbin 4, a varnish 13 impregnated in the entire transformer 1, and mounting holes for mounting the terminals 9 of the transformer 1 on the circuit board 2. 14 are provided respectively.

As described above, in the transformer 1 in which the magnetic core 3 is assembled on the transformer bobbin 4 on which the winding is wound, the winding 6 provided between the terminals of the terminal portion 5 of the transformer bobbin 4 is formed. In order to form the groove 7 for drawing out into a shape as shown in FIG. 1, a molding die 200 shown in FIG.
Is used.

In this figure, the molding die 200 shows a closed state, and illustrates a case where a thermosetting resin capable of satisfying the safety standards of each country such as the above UL standard is transfer-molded. I have. This molding die has a cavity piece 201 and a cavity sandwiched by a cavity piece 202 built in a known die set, and a plurality of terminals 9 are inserted in advance as shown in the figure, and a predetermined resin material is heated at a high temperature and a high pressure. By injecting in this state, the mold is opened from the separation surface after solidification by cooling, and an integrally molded product of the terminal 9, the trans bobbin 4, and the terminal portion 5 is taken out of the mold.

The cavity piece 201 thus constructed
Is formed with a shape portion 201a for forming a groove portion 7 through which a lead wire drawn out of a winding passes between the terminals 9 as shown in FIG. For this reason, after molding, the groove 7
In this case, the shape does not have a stress concentration portion.

That is, as shown in FIG. 3, since the corners of the bottom of the groove 7 are chamfered from multiple sides, the stress caused by the drop impact concentrated on the corner of the groove 107 as in the conventional case is dispersed. Will be. Therefore, when the transformer 1 mounted on the circuit board 2 falls, the winding 6
The stress concentration on the corner of the groove 7 for drawing out can be dispersed, the generation of the crack 15 of the transformer bobbin occurring at the corner of the groove 7 of the winding can be avoided, and the crack of the transformer can be prevented.

In the above configuration, the effect of preventing the transformer bobbin from being broken when the transformer 1 mounted on the circuit board 2 is dropped is effective in all directions regardless of the drop direction. Experiments have shown that it is particularly effective against dropping in any direction.

Next, FIG. 4 is a side view of a transformer showing a second embodiment of the present invention, and FIG. 5 is an enlarged view of a molding die showing a state in which the winding lead-out groove 7 of FIG. 4 is formed. FIG.

In FIGS. 4 and 5, the components already described have the same reference numerals and their description will be omitted. The different configuration will be described. Are formed.

As shown in the above configuration, since the shape of the groove 7 for drawing out the winding is formed by an arched curved surface, the stress concentration on the groove 7 for drawing out the winding is dispersed similarly to the first embodiment. It has the effect of preventing breakage of the transformer bobbin due to a drop impact.

Further, when the transformer bobbin having the shape of the present embodiment is formed, the shape portion 201a corresponding to the portion of the winding lead-out groove 7 of the transformer bobbin has a convex curved surface. Can be improved, the occurrence of burrs at the time of molding is reduced, and it is more suitable for mass production.

According to a drop test in which the transformer 1 before taking the above measures is soldered and mounted on the circuit board 2 and mounted on a case, cracks occur in the pedestal 105 of the transformer bobbin 104. According to the transformer 1 in the form,
Even if the transformer 1 falls from a height 20% higher than the conventional one, the transformer bobbin does not crack and the drop resistance of the transformer 1 can be improved.

FIG. 6 is a side view of a transformer according to a third embodiment of the present invention.

Referring to FIG. 4, the transformer 1 has a structure in which the terminal pitches of the transformer 1 cannot be equal, as shown in FIG.
The shape of the winding groove 7 is the above-mentioned arch shape, but this shape is provided only for a specific groove 7 instead of all of the winding grooves 7 between terminals.

Conventionally, the interval between adjacent terminals of the transformer may not be equal for convenience of transformer winding design and avoiding erroneous mounting when the transformer is mounted on a circuit board. For this reason, such transformers with terminal pitches that are not evenly spaced tend to concentrate stress at specific locations compared to transformers with terminal pitches that are evenly spaced, so there is a possibility that transformer bobbins will crack due to impact due to falling. Will be higher.

Therefore, as shown in FIG. 6, the minimum change of the transformer bobbin forming die to be changed to the same winding groove shape as that of the second embodiment only for a specific winding groove portion 7 where stress tends to concentrate. By applying the same, it is possible to ensure the same transformer bobbin drop strength as in the first embodiment.

Although the measures against the drop of the transformer on the transformer bobbin in the above-described embodiment are for a transformer with a magnetic material core placed horizontally, it goes without saying that a transformer with a magnetic material core placed vertically may be used. .

As described above, since the groove of the winding lead-out portion of the terminal portion of the transformer bobbin of the transformer is formed of a curved surface and a flat surface without corners, the stress due to the drop impact is dispersed, and the Cracking of the terminal portion of the transformer bobbin and occurrence of cracking of the transformer bobbin due to stress concentration can be prevented. In the case of an asymmetrical pin arrangement, stress may be concentrated at one location.In such a case, the shape can be changed by changing the shape of the transformer bobbin molding only at the required location. There is an advantage that can be dealt with with few changes. Also, the surface shape of the trans bobbin molding die corresponding to the groove can be easily separated from the die, and the occurrence of burrs can be reduced.

[0045]

As described above, according to the present invention, the molding material of the transformer bobbin is not changed to a special material, and the manufacturing process is not largely changed. A highly reliable transformer and a transformer bobbin molding die that is not easily destroyed by vibration or drop impact can be provided at low cost.

[0046]

[Brief description of the drawings]

FIG. 1 is a side view of a transformer according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a mold for forming a groove in FIG. 1;

FIG. 3 is an external perspective view showing a state in which the transformer of FIG. 1 is mounted on a circuit board.

FIG. 4 is a side view of a transformer according to a second embodiment of the present invention.

FIG. 5 is an enlarged view of a mold for forming a groove in FIG. 4;

FIG. 6 is a side view of a transformer according to a third embodiment of the present invention.

FIG. 7 is a diagram showing an outer shape of a transformer according to a conventional example of the present invention.

FIG. 8 is a side view of a conventional transformer of the present invention.

FIG. 9 is a side view showing a broken state of a conventional transformer.

FIG. 10 is a side view of a transformer bobbin of a conventional transformer.

FIG. 11 is a side view of a transformer bobbin reinforced in a conventional transformer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transformer 2 circuit board 3 magnetic material core 4 transformer bobbin 5 pedestal of transformer bobbin 8 winding of transformer bobbin 7 groove for drawing out winding of transformer bobbin 8 winding of transformer bobbin 9 terminal 10 copper pattern 11 soldering Part 12 Exterior tape 13 Varnish 14 Terminal mounting hole 15 Crack

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI B29L 31:34

Claims (9)

[Claims] 1. A transformer completed by assembling a magnetic core to a transformer bobbin on which a winding is wound, wherein a plurality of terminals for electrically and mechanically connecting the winding including a method of winding. Is provided on the trans bobbin,
A transformer using a transformer bobbin integrally formed with a groove through which an electric wire drawn from the winding passes between the terminals, wherein the transformer bobbin having no stress concentration portion in the groove is used. And a transformer. 2. The transformer according to claim 1, wherein the transformer bobbin having no stress concentration portion is used by forming the groove portion from a concave curved surface having no acute angle shape. 3. The transformer bobbin having no stress concentration portion by forming the groove portion from a concave polyhedron formed by at least 5 planes or more in which an angle between adjacent surfaces is 90 degrees or more. The transformer according to claim 1, wherein: 4. The transformer according to claim 2, wherein the transformer bobbin continuously formed from an end so as to form the concave curved surface only at the bottom of the groove is used. 5. A transformer using the trans bobbin in which at least one groove portion according to claim 2 or 3 is formed. 6. A transformer bobbin molding die for molding a transformer bobbin, which is completed by winding a winding and assembling a magnetic material core, from a predetermined resin material, the method including a method of kinking. A plurality of terminals for electrically and mechanically connecting windings are insert-molded in the transformer bobbin, and a shape having no stress concentration portion in a groove portion through which an electric wire drawn from the winding passes between the terminals. A molding die for a transformer bobbin, comprising a cavity piece having a cavity portion formed therein. 7. The method according to claim 1, further comprising the step of: forming the cavity piece having a concave curved surface having no acute angle, wherein the transformer bobbin is formed so as not to have the stress concentration portion after the insert molding. 7. The molding die for a transformer bobbin according to 6. 8. The transformer bobbin formed from a concave polyhedron composed of at least five planes having an angle of 90 ° or more between adjacent planes, wherein the trans bobbin has the stress concentration part after the insert molding. The molding die for a trans bobbin according to claim 6, wherein the molding is performed so as not to be performed. 9. The method according to claim 1, further comprising the step of: forming the cavity piece continuously from the end so as to form the concave curved surface only at the bottom of the groove, so that the transformer bobbin does not have the stress concentration portion after the insert molding. The molding die for a transformer bobbin according to claim 6, wherein the molding die is formed.