JP2002008923A - High-frequency transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate thermal damage accidents on account of superior heat radiation, and to reduce noises in a high-frequency transformer. SOLUTION: This high-frequency transformer is provided with a ferrite core of core-type or shell type, a winding as a primary or secondary conductor which is wound around each of cores, and a heat sink material, in which a number of fins are erected dispersedly on the outer surface, and the lower surface of the heat sink material is adhered tightly to at least one side surface of the cores wound by both conductors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency transformer having a core with good heat radiation and little winding damage.

[0002]

2. Description of the Related Art In general, high-frequency transformers have a wide range of frequencies from about 1 kHz to about 60 GHz, and have various structures. For this reason, windings used in high-frequency transformers include wires coated with heat-resistant fluororesin, ordinary enameled wires or wide band-shaped conductors, litz wires in which dozens to hundreds of enameled wires are bundled, or Water-cooled metal pipes and the like are known for high power of kW or more, and need to be appropriately selected according to the application.

For example, for a high-frequency induction heating device,
There is a high-frequency transformer in which a secondary winding is formed by a plate-shaped conductor wound several times in conformity with a core of a core, and the plate-shaped conductor is used as a bobbin of a primary winding as it is. In this high-frequency transformer, a primary winding is wound around an outer peripheral surface of a plate-shaped conductor, and a cooling pipe is fixed in parallel with the primary winding by brazing. In this high-frequency transformer, high current easily flows through the plate conductor of the secondary winding, and it is easy to generate heat. It is difficult to suppress this heat by merely flowing water through the cooling pipe, and the versatility is reduced by suppressing the output power. I do.

[0004]

On the other hand, RF for plasma
The high-frequency transformer used for the power supply easily generates heat even when the output is only about 1 kW, and the temperature of the winding is 200 ° C.
Before and after, it temporarily reaches around 300 ° C. In this high-frequency transformer, a wire whose winding is insulated with polytetrafluoroethylene (PTFE) is generally used. Although this PFTE can be used continuously over a wide temperature range of -90 to 260 ° C, it loses crystallinity and the mechanical strength gradually decreases when the high temperature environment continues.

In this high-frequency transformer, if the PFTE of the coating material is thermally damaged by use in a high-temperature environment for a long period of time, the metal wires as the windings come into direct contact with each other, causing a burnout accident. For this reason, air-cooling of the high-frequency transformer using a cooling fan has been performed. However, the blowing from the fan has a small cooling effect even when blown directly to the core, and cannot prevent the PFTE of the coating material from being thermally damaged in a high temperature environment around 200 ° C. In order to enhance the cooling effect by blowing air, it is necessary to make the winding a plate-shaped conductor and increase the area of the plate-shaped conductor, contrary to miniaturization of the transformer, which leads to an increase in cost.

The present invention has been proposed in order to improve the conventional problems related to the high-frequency transformer, and provides a high-frequency transformer having good heat dissipation, less winding damage, and excellent durability. It is intended to be. Another object of the present invention is to provide a small high-frequency transformer with little noise.

[0007]

In order to achieve the above object, a dry high-frequency transformer according to the present invention comprises an inner iron type or outer iron type ferrite core, and a primary side and a secondary side conductor wound around each core. And a heat sink material having a large number of fins distributed on the outer surface side. In this high-frequency transformer, the lower surface of the heat sink material is densely attached to at least one side surface of the core around which both conductors are wound,
The air from the cooling fan is passed between the fins of the heat sink material to air-cool both conductors. Preferably, the ferrite, which is the magnetic core, is placed horizontally, and the lower surface of the heat sink material is closely adhered to three sides of the core around which the windings, which are the primary and secondary conductors, are wound.

In the present invention, the heat sink material is
In general, it means a cooling component made of a metal having high thermal conductivity such as aluminum or copper and having a number of fins erected on the outer peripheral side so as to enhance a cooling effect by blowing air. The heat sink material may be formed by integrally forming an aluminum plate or a copper plate by cold forging, or may be formed by bending a thin metal sheet into a desired shape or by welding. Each fin is
In general, it is preferable to stand upright in a direction substantially perpendicular to the lower wall, and to make them parallel to the blowing direction in order to increase the contact area with the cool air.

The high frequency transformer of the present invention generally has a generation frequency of 300 kHz to 60 MHz. For example, when targeting a relatively high frequency such as a generated frequency of about 20 MHz or more, a core-type or a core-type ferrite core, and a winding that is a primary-side and a secondary-side conductor wound around each core. And a Peltier element in indirect or direct contact with both conductors, and a heat sink material having a large number of fins dispersedly provided on the outer surface side. In this high-frequency transformer, the lower surface of the heat sink material is densely adhered to at least one side surface of the core around which both the conductors are wound via a Peltier element, and the air from the cooling fan is passed between the fins of the heat sink material so that the two conductors are joined together. Air cool.

A Peltier device is a ceramic material that creates a temperature difference between both surfaces by passing a direct current, and has no cooling ability itself. The Peltier device is generally used for cooling a small refrigerator or CPU by cooling one surface and heating the other surface. The Peltier device can be cooled only by electricity and has a cooling surface of minus several tens degrees.

A high-frequency transformer according to the present invention includes a shell-type ferrite core and windings that are primary and secondary conductors wound around the core, and a large number of fins are directly erected on the outer surface of the core. May be. In this case, the air blown from the cooling fan passes between the fins on the outer surface of the core to air-cool both conductors. Each fin may be formed by engraving a core and integrally formed with the core, or a fin material separate from the core may be attached to the surface of the core by welding, screwing, fitting, bonding or the like.

The high-frequency transformer of the present invention may use a core-type ferrite core. A heat sink material is fitted and attached to the outer periphery of the core around which the primary and secondary conductors are wound, and a cooling fan is provided. Air is passed between the fins of the heat sink material to cool both conductors. In the high-frequency transformer with this configuration, a heat sink material is fitted and attached to the outer periphery of the core around which both conductors are wound via a Peltier element, and the air from the cooling fan is passed between the fins of the heat sink material to effect both conductors. Cooling is also possible.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dry-type high-frequency transformer 1 according to the present invention, as illustrated in FIG.
The core includes windings 5 and 5 ′ (FIG. 4), which are primary and secondary conductors wound around each core, and a heat sink material 7 having a large number of fins distributed on the outer surface. The ferrite core may be either an inner iron type or an outer iron type. The outer iron type has a parallel shape as shown in FIG. 1 or FIG. 3, an eyeglass core as shown in FIG. Either may be used. FIG. 7 shows the high-frequency transformer of the present invention.
It is also possible to directly erect a large number of fins on the outer surface side of the core itself.

The ferrite core 2 is usually wound with a wire material insulated with a heat-resistant fluororesin as each of the windings 5 and 5 ′ as the primary and secondary conductors. PTFE, PFEP, PFTEE, PVF,
What is necessary is just PVdF. As this winding, for example, an ordinary enameled wire or a litz wire obtained by bundling dozens to hundreds of enameled wires can be used. In the present invention,
The windings are shown in FIGS. 3, 4, 7, 9, and 10, but all of them are only partially shown in outline and are not shown in an exact ratio.

The heat sink material 7 may be integrally formed as a whole as shown in FIG. 1, or may be configured by combining a plurality of parts. This heat sink material may be composed of multiple parts when it is in close contact with multiple sides of the ferrite core.Even if each part is assembled with a dovetail groove or adhesive, tighten the whole with bolts and nuts Assembly is also good.

The heat sink material 7 has a lower surface of the heat sink material closely adhered to at least one side surface of the ferrite core. For example, even if the heat sink material surrounds the three side surfaces of the ferrite core 2 as shown in FIG. Only one side of the core may be in close contact. This heat sink material may surround the four side surfaces of the ferrite core, for example, in FIG. 10, surrounds the outer peripheral surface of the core.

The shape of the fin 8 generally has an elongated rectangular front shape as shown in FIG. 1, and extends continuously and parallel in the longitudinal direction. These fins can also be formed intermittently as shown in FIG. Each of the fins 17 shown in FIG. 5 has a wing shape in which the center part is slightly expanded in a horizontal cross section. Further, these fins may be formed of parallel rows in which a number of vertical rods are arranged at equal intervals, and the rows may be arranged while being shifted from each other.

As shown in FIG. 1, the heat sink material 7 is fitted and closely contacted with the cores 2, 2, and a gap between the two is filled with a sealant 15 made of silicone resin, and fixed to the cores 2, 2. Carbon or metal powder may be mixed into the sealant 15 to increase thermal conductivity. The heat sink material 7 and the cores 2 and 2 may be fixed by a thermoconductive double-sided tape (not shown), and the double-sided tape is made of graphite or metal foil as a base material. Although not shown, the heat sink material 7 may be tightly fixed to the cores 2 and 2 with a mounting bracket, and silicon grease mixed with carbon or metal powder may be applied between the two.

The Peltier element 44 shown in FIG. 9 is densely mounted on a rectangular parallelepiped ferrite core, and is adhered tightly to the ferrite core by applying, for example, a silicone resin sealant. If a direct current is passed through the Peltier element 44 and is only interposed on one side surface of the ferrite core as shown in FIG. 9, it is preferable that the side surface is slightly larger than the side surface. This Peltier element is generally flat as shown in FIG. 9, and may be separately mounted to interpose on two or more side faces, or may be appropriately divided and arranged if interposed in a ring shape.

[0020]

Next, the present invention will be described based on examples, but the present invention is not limited to the examples. 1 and 2 illustrate a high-frequency transformer 1 according to the present invention.

The high-frequency transformer 1 includes cylindrical ferrite cores 2 and 2 arranged in parallel as shown in FIG. 3, and is connected to metal plates 4 and 4 by metal cylinders 3 inserted into the respective cores. Construct a plane. The metal cylinder 3 and the metal plate 4 are usually made of copper or brass.

Windings 5 that are primary and secondary conductors
5 ', as shown in FIGS. 3 and 4, is alternately or substantially concentrically wound around metal tubes 3, 3 inserted into the ferrite core 2 and wound substantially horizontally. These windings 5,
5 ′ is a wire rod insulated with heat-resistant PTFE,
The number of turns of each winding is about several tens at a generation frequency of 300 kHz.

The heat sink material 7 (FIG. 1) is an aluminum material in which a large number of fins 8 are integrally erected on the outer surface side by cold forging. By forming the fins 8, the contact surface area with the air is extremely low. Big. The heat sink material 7
When viewed from the front as shown in FIG. 1, it has a substantially rectangular plane. The heat sink material 7 has such a structure as to cover three side surfaces of the ferrite cores 2 and 2, and each fin 8 extends in parallel in the longitudinal direction as shown in FIG.
It is almost the same length as.

Each of the fins 8 has an elongated rectangular front shape, and includes a vertical fin 10 provided on a horizontal plane and horizontal fins 12 provided on both side surfaces. The vertical fins 10 are longer than the horizontal fins 12 and slightly shorter than the diameter of the core 2, but have an interval of about twice the fin width between each fin. On the other hand, the horizontal fin 12
Is less than half the length of the vertical fin 10,
The fins are arranged at a narrow interval about the fin width.

The fins of the heat sink material extend continuously in the longitudinal direction in FIG. 2, but can be formed intermittently as shown in FIG. The fin 17 shown in FIG. 5 has a wing shape in which a central portion is slightly expanded in a horizontal cross section, and the wind hitting each fin flows smoothly due to the wing shape cross section.

When viewed from the front as shown in FIG. 1, the heat sink material 7 has a rectangular concave portion 9 in the longitudinal direction at the center of the lower surface thereof, the rectangular concave portion 9 being fitted to the core 2. The height of the recess 9 is substantially equal to that of the core 2 and the arc-shaped shallow groove 1 is formed on the inner wall of the recess.
3 and 13 are formed. The inner width of the concave portion 9 is the core 2,
2 are formed, and the shallow grooves 14 are formed on both inner side walls of the recess. Shallow groove 13, 13, 14, 1
The formation of the heat sink member 4 allows the heat sink material 7 to be closely fitted to the cores 2 and 2.

The heat sink material 7 is inserted into the cores 2 and 2 in parallel from the longitudinal direction, and a silicone resin sealant 15 is applied between the cores 2 and 2 to firmly adhere to the cores 2 and 2. A small amount of carbon or metal powder is mixed into the sealant 15 in order to increase thermal conductivity. Next, as shown in FIG. 4, the winding 5 is alternately passed through both metal cylinders from one end face of the metal cylinders 3 and 3, and the winding 5 ′ is passed from the other end face of the metal cylinders 3 and 3. Wind almost horizontally. In the metal cylinders 3,3,
An insulating sheet (not shown) may be wound in advance.

The high-frequency transformer 1 is, for example, as shown in FIG. 6, inside a plasma RF power supply device 16 (all components not related to the present invention are omitted) so as to be orthogonal to a cooling fan 18 located in front. Arrange and bottom plate 2
Stick horizontally on 0. For this reason, the air blown from the cooling fan 18 is sent in the direction of the arrow in FIG. 6, flows in the longitudinal direction along the groove 21 between the fins of the heat sink material 7, and further passes through the mesh 22 on the side wall of the device. Go out of the device.

In the device 16, the air blown from the cooling fan 18 is applied to the groove 2 between the fins of the heat sink material 7.
1, and the coils 5, 5 ′ wound around the metal cylinders 3, 3 via the cores 2, 2 via the heat sink material 7 are air-cooled substantially uniformly over the entire length. By the forced air cooling, for example, in a high-frequency transformer having a generation frequency of 300 kHz to 60 MHz, the windings 5 and 5 ′ generate heat by 8 mm.
0 to about 120 ° C. As a result, winding 5,
The PFTE, which is a coating material of 5 ′, is not thermally damaged even if used for a long period of time, and prevents the windings 5, 5 ′ wound around the cores 2, 2 from being burned out. In addition, the heat sink material 7 is
Even if it is put on, the generation of the radiation wave does not increase, the noise is reduced and the frequency stability is increased.

FIGS. 7 and 8 show a modification of the present invention, in which the ferrite core 24 of the high-frequency transformer 23 is generally called an eyeglass core. The core 24 has a pair of through-holes 26, 26 arranged horizontally in the longitudinal direction, and the whole shape is elongated with a substantially rectangular cross section. As shown in FIG. 7, the windings 28 as primary and secondary conductors are alternately passed through the through holes 26, 26 of the ferrite core 24 and wound substantially horizontally.
Alternate or concentric. These windings 28 are wires covered with heat-resistant PTFE, and the number of turns of each conductor is about several tens at a generating frequency of 300 kHz.

When viewed from the front as shown in FIG. 7, the ferrite core 24 has a large number of fins 30 on three side surfaces thereof.
And each fin has an elongated rectangular side surface. As shown in FIG. 8, each fin 30 extends parallel to the longitudinal direction over the entire length of the core 24. Many fins 30
The fins 32 and 34 are made up of vertical fins 32 and horizontal fins 34, 34, each of which is about twice as long as the fin width and arranged at intervals of about the fin width.

In the high-frequency transformer 23, air blown from a cooling fan (not shown) flows along a groove between the fins 30, 30 in the core 24, and passes through the winding 24 through the core 24 over substantially the entire length. Air cool evenly. By this forced air cooling, the heat generation of the windings 28 is reduced to 80 to 120 ° C. As a result, PFT which is a coating material of each winding 28
E is not thermally damaged even when used for a long period of time, thereby preventing the winding 28 from burning. Further, in the core 24, the generation of the radiation wave does not increase, the noise is reduced, and the frequency stability is increased.

FIG. 9 shows another modification of the present invention, in which a ferrite core 41 of a high-frequency transformer 40 is an eyeglass core, and has a pair of through holes 42, 42 arranged horizontally in the longitudinal direction. The windings 43, which are primary and secondary conductors, are wound alternately or concentrically around the through holes 42, 42, and the number of windings of the winding 43 is usually more than ten.

The known Peltier element 44 is densely placed on the rectangular parallelepiped core 41, and is tightly adhered to the core 41 by applying a silicone resin sealant. Peltier element 4
It is preferable that the plane shape of 4 is slightly larger than that of the core 41 because the cooling effect is enhanced. The Peltier element 44 includes
A direct current is supplied from the cord 45. Peltier element 44
If the heat conduction between the core and the core 41 is insufficient, a buffer plate (not shown) made of pure copper may be interposed.

The heat sink material 46 is a Peltier device 4
Glue on 4 The planar shape of the heat sink material 46 is
It is the same as that of the Peltier element 44 and slightly larger than that of the core 41. Since the heat sink material 46 usually has a high temperature in the Peltier element 44, it is desirable that the number of the fins 48 is large and the groove 50 between the fins is deep in order to enhance the cooling effect.

Regarding the high frequency transformer 40, the core 41
Is strongly cooled by the Peltier element 44, and heat generated in the Peltier element is eliminated by the heat sink material 46. Ventilation from a cooling fan (not shown) flows along the groove 50 between the fins in the heat sink material 46 and cools both conductors wound around the core 41 through the heat sink material 46 and the Peltier element 44 almost uniformly. .
By this forced cooling, for example, in a high-frequency transformer having a generation frequency of 27 MHz or more, heat generation is reduced to about 100 ° C., thereby avoiding thermal damage to PFTE, which is a coating material of each winding 43, and preventing the winding from being burned. I do.

In the high-frequency transformer 52 shown in FIG.
An annular ferrite core 54 is used, and the core has an appropriate thickness. Windings 56 and 58 as primary and secondary conductors are wound around the core 54, and half-split heat sink materials 60 and 60 are fitted and attached to the outer periphery of the core. A number of fins 62 are erected on the outer peripheral side of the heat sink members 60 and 60 in a radial manner.

A sealant of silicone resin is applied to the outer peripheral surface of the core 54, and the heat sink materials 60, 60 are fitted and firmly adhered. The high-frequency transformer 52 is mounted in a standing state as shown in FIG. 10, and the air from a cooling fan (not shown) is passed between the fins 62 of the heat sink materials 60, 60 to air-cool the windings 56, 58. As a result, the PFTE, which is a coating material for the windings 56 and 58, is not thermally damaged even if used for a long period of time, and the windings 56 and
58 accidents are prevented beforehand.

Although not shown, the high-frequency transformer 5
In 2, the heat sink material may be fitted and attached to the outer periphery of the annular core around which both windings are wound via a Peltier element. In this case, even if the generation frequency of the dry-type high-frequency transformer is about 20 MHz or more, the heat generation of the primary and secondary conductors can be reduced to about 100 ° C., thereby preventing a transformer heat loss accident.

[0040]

According to the high frequency transformer of the present invention, a large number of fins are dispersed and provided on the outer surface side of the heat sink material attached to the ferrite core itself or the core, so that the air from the cooling fan can be blown from the core itself or the heat sink material. In the groove between the fins. As a result, the two conductors wound directly or indirectly on the core are air-cooled substantially uniformly over the entire length, and the heat generation temperature of the windings, which are both conductors, is reduced to 80 to 120 ° C. Due to this forced air cooling, the fluororesin, which is a coating material for each winding, is not thermally damaged even if used for a long period of time, thereby preventing the winding wound around the core from burning.

In the high-frequency transformer of the present invention, if a Peltier element is interposed between the heat sink material and the ferrite core, the two conductors wound around the core can be cooled more effectively. In this case, even if the generation frequency of the high-frequency transformer is about 20 MHz or more, the heat generation of the primary and secondary conductors is suppressed to about 100 ° C., and the heat damage of the coating material is avoided to prevent the winding from being burnt. This prevents a heat loss accident of the high-frequency transformer.

In the high-frequency transformer of the present invention, even if a large number of fins are formed on the core or a heat sink material is covered on the ferrite core, the generation of radiation waves does not increase. When the high-frequency transformer of the present invention is used, noise is reduced and frequency stability is increased, and the RF for plasma is reduced.
More suitable as a power source.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a high-frequency transformer to which a heat sink material is attached, with windings omitted.

FIG. 2 is a side view of the high-frequency transformer of FIG.

FIG. 3 is a schematic front view illustrating a high-frequency transformer to which the present invention is applied;

FIG. 4 is a side view of the high-frequency transformer of FIG.

FIG. 5 is a horizontal sectional view showing a modification of the heat sink material.

FIG. 6 is a horizontal sectional view showing a main part of a plasma RF power supply device provided with a high-frequency transformer.

FIG. 7 is a schematic front view showing a modification of the high-frequency transformer.

FIG. 8 is a side view of the high-frequency transformer of FIG. 7;

FIG. 9 is a schematic front view showing another modification of the high-frequency transformer.

FIG. 10 is a schematic plan view showing still another modification of the high-frequency transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency transformer 2, 2 Ferrite core 3, 3 Metal cylinder 4, 4 Metal plate 5, 5 'winding 7 Heat sink material 8 Fin

Claims (5)

[Claims] 1. A dry-type high-frequency transformer, comprising a core-type or a core-type ferrite core, windings serving as primary and secondary conductors wound around each core, and a large number of fins distributed on an outer surface side. A heat sink material provided, and a lower surface of the heat sink material is densely adhered to at least one side surface of the core around which both the conductors are wound, and the air from the cooling fan is passed between the fins of the heat sink material to cool both the conductors. High frequency transformer. 2. A dry-type high-frequency transformer for a relatively high frequency, comprising: a core-type or a core-type ferrite core; windings, which are primary and secondary conductors, wound around each core; And a heat sink material in which a number of fins are erected on the outer surface side indirectly or directly, and at least one side of a core around which both conductors are wound is provided with a heat sink material via a Peltier element. A high-frequency transformer that cools both conductors by tightly attaching the lower surface and passing the air from the cooling fan between the fins of the heat sink material. 3. A ferrite core of an inner iron type or an outer iron type is horizontally installed, and the lower surface of a heat sink material is closely adhered to three side surfaces of a core around which windings as primary and secondary conductors are wound. The high-frequency transformer according to claim 1. 4. A dry-type high-frequency transformer, comprising: a shell-type ferrite core; and windings serving as primary and secondary conductors wound around the core, and a large number of fins standing directly on an outer surface of the core. A high-frequency transformer that cools both conductors by passing air from a cooling fan between the fins on the outer surface of the core. 5. A dry-type high-frequency transformer, wherein an inner-iron-type ferrite core, windings serving as primary and secondary conductors wound around the core, and an annular heat sink having a large number of fins erected on an outer peripheral side thereof. With a heat sink material fitted and attached to the outer periphery of the core around which both conductors are wound,
A high-frequency transformer that cools both conductors by passing the air from the cooling fan between the fins of the heat sink material.