JP2001237125A - Coil bobbin and transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a divided coil bobbin which can efficiently radiate heat produced in a coil, as well as a transformer using the divided coil bobbin. SOLUTION: In a divided coil bobbin 6 which is divided into a plurality of layers for coil winding by a flange 7, the coil bobbin 6 is made of polymer material, and slits 7 are formed in the flange 7 and their outer sides are open in the outer circumference of the coil bobbin core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coil bobbin and a transformer using the coil bobbin.

[0002]

2. Description of the Related Art In recent years, switching power supplies have become T
It is used for home appliances such as personal computers and personal computers, and control power supplies for various facilities used in the industrial field. In recent years, in order to deal with environmental issues, applications to electric vehicles, fuel cell vehicles, or gasoline-driven and motor-driven hybrid vehicles, which are driven by a motor that does not generate exhaust gas, have been increasingly used in vehicles.

What is required of these power supply devices is a reduction in size, thickness, weight, reliability, and efficiency.

The power transformers mounted on these power supply devices have a problem in that the temperature rises due to the heat generated by the coil windings during operation. When the temperature rises, thermal stress is generated in the filling and sealing resin in the resin mold type transformer, which leads to dielectric breakdown such as resin cracks, thereby impairing the reliability of the transformer, ie, the reliability of the power supply.

[0005] The temperature rise can be suppressed by increasing the coil wire diameter, but this leads to an increase in the size of the power supply.

Moreover, the rise in the temperature of the transformer leads to a decrease in the conversion efficiency as the power supply performance, and the greater the heat generation, the worse the conversion efficiency. Poor conversion efficiency results in extra power consumption, which is economically and environmentally undesirable.

[0007] From such a background, as a power supply transformer used in a switching power supply, a small-sized transformer having good heat dissipation is desired.

The following is a conventional technique for suppressing a rise in temperature due to heat generation in a coil winding portion of a power transformer.

In general, when the heat generated by the coil is large, a technique of increasing the coil wire diameter and decreasing the resistance to suppress the temperature rise is used. However, increasing the wire diameter leads to an increase in the size of the power supply. Usually, there is a restriction on the required power supply size, and increasing the wire diameter is only allowed within a limited range, which is not preferable.

In addition, a coil bobbin divided into several layers by a flange portion is used, and the exterior is filled and sealed with an insulating resin having good thermal conductivity which also serves as electrical insulation, so that the heat generated by the coil winding is filled with the resin. There is a method of suppressing a temperature rise while keeping the coil wire diameter as it is by radiating heat to the outside. However, in this case, the filling resin having good thermal conductivity comes into contact with the coil winding only on the outside of the coil winding portion, and the other coil portions are in contact with the coil bobbin material. In general, thermoplastic molding materials used for coil bobbins cannot be added with a large amount of a filler that improves thermal conductivity from the viewpoint of improving moldability, and as a result, a filler resin represented by an epoxy resin cannot be used. Thermal conductivity is poor as compared. For this reason, in the above-mentioned method, there has been a problem that heat radiation inside the coil winding portion is poor.

In the coil device, Japanese Patent Laid-Open No. 11-21 / 1999
As described in Japanese Patent No. 4231, in order to prevent breakage in the secondary coil portion due to heat generation in the primary winding portion, a plurality of extending portions are formed in the radial direction from the bobbin, 1
The secondary winding portion is configured to be exposed from the extended portion to the upper surface to enhance the heat radiation effect.

[0012] However, this has a problem of a temperature rise caused only by the primary coil for a limited use as an ignition coil, and a slit is provided only in a flange portion outside a layer on which the primary coil is wound. However, the problem of temperature rise present in both the primary coil and the secondary coil, which is the object of the present invention, cannot be solved only by providing a slit only on the outermost flange on the primary coil side of the coil bobbin.

[0013]

In the conventional split bobbin structure made of a thermoplastic polymer material, there is a problem that the heat generated in the coil cannot be efficiently dissipated. Therefore, a power supply using the split coil bobbin has a problem. In the transformer, the power transformer becomes large in size for high reliability and high conversion efficiency, and there is a problem that the power supply device cannot be reduced in size and weight.

Accordingly, the present invention provides a coil bobbin that can efficiently radiate heat generated in the coil winding portion with a simple structure by devising the shape of the coil bobbin, and by using this coil bobbin. It is an object of the present invention to provide a transformer capable of achieving a small size and high reliability.

[0015]

An outline of the present invention will be described with reference to FIG. In FIG. 1, 6 is a coil bobbin of the present invention, 11 is a slit, and 12 is a core. The above object of the present invention can be achieved by the following constitutions (1) to (4).

(1) In the split coil bobbin 6 divided into a plurality of layers for coil winding by the flanges 7, the split coil bobbin 6 is made of a thermoplastic polymer material. The slit 11 formed in the flange 7 is characterized in that the inside is open from the outer periphery of the coil bobbin core 12 to the outside.

(2) In the transformer using the split coil bobbin 6 divided into a plurality of layers for coil winding by the flange portion 7, the split coil bobbin 6 is made of a thermoplastic polymer material. A primary coil and a secondary coil are separately wound on each of the divided layers, and the divided coil bobbin 6 and the primary and secondary coils are molded with a thermosetting insulating resin. It is characterized by.

(3) In the transformer of (2), one end of the split coil bobbin 6 is disposed on a metal block and molded with a thermosetting insulating resin.

(4) In the transformer according to (3), the metal block includes a bottom located at an end of the split coil bobbin 6, and an extension extending from the bottom to a flange side of the split coil bobbin 6. It is characterized by having done.

Thus, the following operation and effect can be obtained.

(1) The split coil bobbin is made of a thermoplastic polymer material which is easy to mold, and slits are formed in all the flanges of the coil bobbin. Since the coil is formed, when the winding is wound around the coil bobbin and molded with a thermosetting insulating resin, the molded thermosetting resin between the layers is continuous through the slit. Then, heat generated from the windings is transmitted to the continuous portion via the slit and transmitted to the upper and lower outer circumferences, so that the heat radiation effect is improved, and a split coil bobbin with good heat radiation characteristics can be provided.

(2) As described above, since the transformer is manufactured using the split coil bobbin having excellent heat transfer, a transformer having good heat radiation characteristics can be provided.

(3) The above-described split coil bobbin having excellent heat transfer is used, and the end of the split coil bobbin is molded with a thermosetting resin having good heat conduction properties in a state close to a metal block having good heat radiation properties. Thus, heat generated from the coil can be efficiently transmitted to the metal block at one end of the split coil bobbin, and the heat radiation characteristics can be improved.

(4) Since the metal block is formed with an extension extending toward the flange of the split coil bobbin, the heat of the internal coil of the thermosetting resin passes through the flange to the metal block. And the heat dissipating effect can be further improved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 shows a split coil bobbin in one embodiment of the present invention, FIG. 2 shows a power transformer in one embodiment of the present invention using the split coil bobbin, and FIG. 2 shows a power transformer in the present invention using the split coil bobbin. FIG. 3 shows a power transformer according to an embodiment, and
Shows an external view of this power transformer.

In the figure, 1 and 1 'are ferrite cores, 2 is a sealing resin, 3 is a metal block provided for heat dissipation,
Reference numeral 4 denotes a connection lead portion of the primary coil, 5 denotes a connection lead portion of the secondary coil, 6 denotes a split coil bobbin, 7a to 7e denote flanges, and 8
a and 8b are primary coils, 9a and 9b are secondary coils, 11
Denotes a slit, and 12 denotes a core of the split coil bobbin.

The power transformer is designed to improve heat dissipation.
A case material molded of a thermoplastic polymer material that is usually used is not used, and a filling and sealing resin 2 made of a thermosetting resin such as an epoxy resin also serves as an outer case.

The power transformer is a metal block 3
Is installed on the housing of the power supply circuit, not shown, with
The metal block 3 plays a role of heat radiation.

The metal block 3 includes a primary coil 8a,
Heat generated in the 8b and the secondary coils 9a and 9b and transmitted through the filling sealing resin 2 is radiated to the power supply housing (not shown) through the metal block 3. The metal block 3 includes a bottom portion 3-1 and an extended heat receiving portion 3 extending substantially vertically from the bottom portion 3-1.
-2, and projections 3-3 and 3-3 in contact with split coil bobbin 6
4 and a groove 3-5 are provided, and the lower surface of the split coil bobbin 6 is also filled with the sealing resin 2.

As shown in FIG. 2A, the extended heat receiving section 3-2 is desirably located at the uppermost coil portion, but the present invention is not limited to this. The extended heat receiving section 3-2 can immediately receive and cool the heat generated from the primary coils 8a and 8b and the secondary coils 9a and 9b via the filling sealing resin 2. Metal block 3
Is made of a metal having good heat conductivity, for example, aluminum or aluminum alloy.

The split coil bobbin 6 includes a core 12 and a plurality of flanges 7a, 7b, 7c, 7d, 7e. Each Tsuba 7a
7e, a plurality of slits 11 are formed. The split coil bobbin 6 is made of a thermoplastic polymer material for ease of molding.

The inside of the slit 11 is formed up to the outer periphery of the core 12 of the split coil bobbin, and the outside is open, but the present invention is not limited to this. Further, it is desirable that the slits 11 formed in one flange are formed at equal intervals, but the present invention is not limited to this. The position where the slit is formed is desirably the same position as each flange portion, but this is not essential.

The split coil bobbin 6 is wound up and down so as to sandwich the secondary coil in order to improve the coupling between the primary coil and the secondary coil of the transformer. That is, the collar 7
The primary coils 8a and 8b are wound 16 turns in parallel between a, 7b and 7d and 7e.
b, 7c and secondary coils 9a, 9b between 7c, 7d
It is wound in series for 16 turns and 32 turns in total.
Of course, the number of turns and the winding system of each coil are not limited to these.

The heat generated by these coil windings is radiated to the outside air through the filling and sealing resin 2 and to the power supply housing through the metal block 3. Heat is also dissipated through the ferrite cores 1 and 1 '.

FIG. 1 shows each of the flanges 7a to 7a of the split coil bobbin 6.
FIG. 7e shows a case where slits of the same shape are formed at the same position at equal intervals. When a slit is formed at the same position, and when this is sealed with the filling sealing resin 2, the heat conduction path is formed straight through each slit, so that the heat conductivity to the metal block 3 is improved. it can.

Next, a simple method of manufacturing a power transformer using the split coil bobbin 6 will be described.

The metal heat dissipation block 3 is set in a metal mold (not shown) manufactured so as to form the external shape of the power transformer. The above 1
The split coil bobbin 6 provided with the secondary coil and the secondary coil is installed. The connection lead portions 4 and 5 of each coil are fixed by a jig not shown.

A thermosetting resin such as an epoxy resin is filled and sealed as the filling and sealing resin 2. This filling method is not limited to a potting method, a transfer molding method, or the like, but is preferably performed in a vacuum in order to fill the slit 11 with a resin. After curing for a predetermined time,
After removing from the mold, the main part of the power transformer is completed.

Thereafter, in the split coil bobbin 6, FIG.
As shown in FIG. 3, ferrite cores 1 and 1 'are inserted,
Complete the power transformer. FIG. 2C shows a PQ core as an example of the ferrite cores 1 and 1 ', and shows a case where two ferrite cores 1 and 1' are used as shown in FIG. 2A. These ferrite cores 1, 1 'are shown in FIG.
As shown in (C), the columnar portion 1-0 is formed in the same shape, and is inserted into the core portion 12 of the divided coil bobbin 6 at the center.

Next, an example in which the method of measuring the temperature rise of the coil winding in the power transformer according to the present invention and the results thereof are compared with the conventional example will be described.

As a measurement object, a power transformer using a split coil bobbin in which slits are formed in each flange as shown in FIG. 1 and a conventional type in which only a flange 20 having no slit is formed as shown in FIG. An improved split coil bobbin 2 using a power transformer using a split coil bobbin 21 and a flange 27 having a slit 26 formed only on the outside as shown in FIG.
5 was used.

As shown in FIG. 4, each of the split coil bobbins measures the temperature of the primary coil 8a wound on the uppermost layer with the thermocouple 15, and turns the secondary coil 9a wound on the two-layer part from above. Was measured with a thermocouple 16. FIG. 4A shows a state in which the upper ferrite core 1 is removed to clearly show the positions of the thermocouples 15 and 16, but when actually measured, the upper ferrite core 1 is also attached. went.

The split coil bobbins of each power transformer used for the measurement have the same material and the same shape, and the slits formed in the flange are also the same.

As the members used, the split coil bobbin 6 of the present invention, the conventional split coil bobbin 21, and the improved split coil bobbin 25 both use polyphenylene sulfide resin Ryton R-4 (containing 40% GF, manufactured by Toray Industries, Inc.). The epoxy resin XNR501 is used as the filling sealing resin 2.
5 / XNH5015 (manufactured by Nagase Chiba Co., Ltd.), and aluminum A50 was used as the metal block 3 for heat radiation.
52, the primary coils 8a and 8b and the secondary coil 9
As a and 9b, the litz wire 2UEW 7/41 / 0.0
8 (manufactured by Tokyo Special Electric Cable Co., Ltd.). As the thermocouples 15 and 16 for temperature measurement, those of type T (manufactured by Ninomiya Electric Wire Co., Ltd.) were used.

The power transformers manufactured by using these divided coil bobbins are respectively incorporated in a power supply device (not shown), the power supply devices are operated under predetermined conditions, and the primary coils 8a, 2 The temperature rise of the secondary coil 9a was measured. The temperature at the time when the temperature rise was almost stabilized was read, and was taken as the temperature rise value (ΔT).

When the temperature rise value of the power transformer using the conventional split coil bobbin 21 shown in FIG. 5 is set to 100%, the split coil bobbin 6 of the present invention and the improved split coil bobbin 25 shown in FIG. FIG. 7 compares the temperature rise values of the primary coil 8a and the secondary coil 9a of the used power transformer.

7A shows the temperature rise of the primary coil and the secondary coil of the power transformer using the conventional split coil bobbin 21 shown in FIG. 5, and FIG. 7B shows the improved split coil bobbin shown in FIG. Of power transformer using 25
The temperature rise values of the secondary coil and the secondary coil are shown, and C and D show the temperature rise values of the primary coil and the secondary coil of the power transformer using the split coil bobbin 6 of the present invention.

In the case where the split coil bobbin 6 of the present invention is used, D indicates a temperature rise value when the metal block 3 is used, and C indicates a temperature rise value when the metal block 3 is not used. Show.

Thus, it is understood that the temperature rise of the primary coil 8a and the secondary coil 9a is reduced when the split coil bobbin of the present invention is used. Moreover, in the present invention,
It can be seen that the use of the metal block 3 further reduces the temperature rise of the primary coil 8a and the secondary coil 9a.

[0050]

According to the present invention, the following effects can be obtained.

(1) The split coil bobbin is made of a thermoplastic polymer material that is easy to mold, and slits are formed in all the flanges of the coil bobbin. Since the coil is formed, when the winding is wound around the coil bobbin and molded with a thermosetting insulating resin, the molded thermosetting resin between the layers is continuous through the slit. Then, heat generated from the windings is transmitted to the continuous portion via the slit and transmitted to the upper and lower outer circumferences, so that the heat radiation effect is improved, and a split coil bobbin with good heat radiation characteristics can be provided.

(2) As described above, since the transformer is manufactured by using the split coil bobbin having excellent heat transfer, a transformer having good heat radiation characteristics can be provided.

(3) The split coil bobbin having excellent heat transfer is used, and the end of the split coil bobbin is molded in close proximity to a metal block having a good heat radiation property with a thermosetting resin having a good heat conduction property. Thus, heat generated from the coil can be efficiently transmitted to the metal block at one end of the split coil bobbin, and the heat radiation characteristics can be improved.

(4) Since the metal block is formed with an extension extending toward the flange of the split coil bobbin, the heat of the internal coil of the thermosetting resin passes through the flange to the metal block. And the heat dissipating effect can be further improved.

[Brief description of the drawings]

FIG. 1 is an embodiment of a split coil bobbin of the present invention.

FIG. 2 is an embodiment of a transformer of the present invention.

FIG. 3 is an external view of a transformer according to an embodiment of the present invention.

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

FIG. 5 is an explanatory view of a conventional split coil bobbin.

FIG. 6 is an explanatory view of an improved split coil bobbin.

FIG. 7 is an explanatory diagram of a temperature rise measurement result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1 'Ferrite core 2 Filling and sealing resin 3 Metal block 4 Primary coil connection lead part 5 Secondary coil connection lead part 6 Coil bobbin 7 Flange 8a, 8b Primary coil 9a, 9b Secondary coil 11 Slit 12 core

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E043 AA02 AB01 DA02 DA06 5E044 AA01 AB01 AC01 AD03 BA01 BA06 BB02 BB03 BB08 BC03 5E050 AA10

Claims (4)

[Claims] 1. A split coil bobbin divided into a plurality of layers for coil winding by a flange, wherein the split coil bobbin is made of a thermoplastic polymer material, and slits are formed in all the flanges. The coil bobbin structure, wherein the slit formed in the portion is open on the inside from the outer periphery of the coil bobbin core. 2. A transformer using a split coil bobbin divided into a plurality of layers for coil winding by a flange, wherein the split coil bobbin is made of a thermoplastic polymer material, and slits are formed in all the flanges. A primary coil and a secondary coil are separately wound on each of the divided layers, and the divided coil bobbin and the primary and secondary coils are molded with a thermosetting insulating resin. . 3. The transformer structure according to claim 2, wherein one end of said split coil bobbin is arranged in a metal block and molded with a thermosetting insulating resin. 4. The split metal bobbin according to claim 3, wherein the metal block has a bottom portion located at an end of the split coil bobbin and an extension extending from the bottom portion to the flange portion side of the split coil bobbin. Transformer structure.