JP2684593B2 - Coil device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil device such as a noise filter having a coil having a magnetic core wound around it, and more particularly to a coil device having good heat dissipation in the winding portion.

[0002]

2. Description of the Related Art A conventional coil device of this type is shown in FIG. The coil device of FIG. 10 includes a metal case 1, a choke coil 2 in which a winding 5 formed by winding a wire 4 such as an enameled wire around a magnetic core 3 such as ferrite is provided, and a capacitor 6. . Then, the sheet-like insulating member 7 is arranged on the inner bottom surface of the case 1, the choke coil 2 is placed on the sheet-like insulating member 7, and the lead wire of the choke coil 2 and the lead wire of the capacitor 6 are provided to the case 1 via the insulating terminal block 8. In addition to being connected to the fixed metal terminal 9, the inside of the case is cast with a casting material 10 such as insulating resin so that most of the choke coil 2 and the capacitor 6 are immersed. The heat generated by the choke coil 2 is transmitted to the metal case 1 through the casting material 10 and is radiated there.

[0003]

The conventional structure shown in FIG. 10 has the following drawbacks.

(1) The casting material 10 is also applied to the magnetic core 3 of the choke coil 2, and as a result, mechanical stress is applied to the magnetic core 3 and the magnetic characteristics of the magnetic core 3 deteriorate.

(2) In order that the casting material 10 is not applied to the magnetic core 3 and the casting material 10 is applied only to the wire portion 4 of the winding 5, the casting amount of the casting material 10 should be strictly controlled. Although it must be done, strict control of the casting volume in the manufacturing process is actually quite difficult. Further, even a slight variation in the casting amount causes a change in the volume of the wire rod dipped in the casting material 10, resulting in a variation in heat dissipation characteristics.

(3) Since the casting material 10 is cast over the entire bottom surface of the metal case 1, the casting amount of the casting material 10 is large and the cost is high.

[0007] Incidentally, the actual application proposed by the present applicant is 3-1010.
No. 36 proposes a structure in which a choke coil placement resin reservoir is formed on a metal bottom plate, a choke coil is placed in the resin reservoir, and a casting resin is cast into the resin reservoir. Limits the casting range to the inside of the resin reservoir to save the amount of casting resin. However, if the casting amount of the casting resin into the resin pool becomes too large, the casting resin may be applied to the magnetic core or the casting resin may overflow to the outside, resulting in defective products. I have a great dislike.

[0008] A first object of the present invention is to solve the above problems,
Make sure that the magnetic core of the coil is not immersed in the casting material,
It is an object of the present invention to provide a coil device that prevents deterioration of the magnetic characteristics of the magnetic core and improves the characteristics of the coil.

A second object of the present invention is to provide a coil device capable of improving the casting workability of the casting material, stabilizing the casting amount, and further stabilizing the heat radiation characteristics.

A third object of the present invention is to provide a coil device in which the casting amount of the casting material is limited to the necessary minimum to reduce the casting amount and to reduce the cost.

Other objects and novel features of the present invention will be clarified in Examples described later.

[0012]

In order to achieve the above object, a coil device of the present invention comprises a coil having a magnetic core provided with windings, and an inner wall portion and an outer wall portion which form a casting material reservoir. The casting frame is provided with a double wall portion and a bottom hole inside the inner side wall portion, and a base mounted on the lower surface of the casting frame to close the hole. The coil is arranged on the casting frame so that the winding is located inside the inner wall portion, and at least a part of the inner wall portion is at the same height as the lower surface of the magnetic core or the lower surface. The winding is fixed to the casting frame and the base with a casting material formed at a lower height and cast inside the inner wall portion.

When the magnetic core is an abutting structure of a plurality of core members, the core members may be biased in the abutting direction by a core retainer integrally formed on the base. At this time, the core retainer and the core member may be insulated from each other.

Further, a thin portion interposed between the winding and the base may be integrally formed on the bottom of the casting frame.

A locking portion for locking the magnetic core may be formed integrally with the casting frame.

[0016]

In the coil device of the present invention, since the casting height of the casting material is defined by the height of the inner wall portion of the double wall portion formed in the casting frame, this inner wall portion is defined. The height of the magnetic core is set to be the same as the lower surface of the magnetic core of the coil, or is set lower than the lower surface of the magnetic core to prevent the magnetic core from immersing in the casting material, and the stress of the casting material (Note that the stress applied to the magnetic core is small when the casting material contacts the bottom surface of the magnetic core, which is acceptable.) Therefore, it is possible to prevent the magnetic characteristics of the magnetic core from deteriorating and improve the performance of the coil.

Further, even if the casting amount of the casting material fluctuates and becomes excessive, the casting material overflowing from the inner side wall portion enters between the inner side wall portion and the outer side wall portion and stops there. In addition to preventing inadvertent outflow, the casting amount in the inner wall portion, which affects the heat radiation characteristics, can be maintained at a constant amount determined by the height of the inner wall portion. Therefore, the heat radiation characteristics of the coil can be stabilized, the casting amount can be easily controlled, and the casting workability can be improved.

Further, by appropriately setting the position of the inner wall portion, it is possible to reduce the amount of casting material by reducing the casting range to the necessary minimum and to reduce the cost.

When the magnetic core is an abutting structure of a plurality of core members, the core members may be biased in the abutting direction by elasticity of a core retainer integrally formed on the base. It is possible, and in this case, the step of applying an adhesive to the abutting surfaces of the core members and holding the core members in an abutted state until the adhesive cures can be omitted, which facilitates manufacturing and assembly. it can. At that time, by insulating the core retainer and the core member from each other with an insulating member such as an insulating plate,
It is possible to improve the electrical characteristics of the coil (improvement of impedance characteristics).

Further, when a thin portion interposed between the winding and the base is integrally formed on the bottom of the casting frame, the winding and the base become a problem when the base is made of metal. The electrical insulation between them can be performed reliably and easily.

Further, when the locking portion for locking the magnetic core is integrally formed on the casting frame, it is possible to prevent the magnetic core from being lifted up during the casting work, and to prevent the magnetic core from changing its position in the height direction. It can be set so that the wire material portion of the winding is surely cast with the casting material.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a coil device according to the present invention will be described below with reference to the drawings.

FIGS. 1 to 7 show a first embodiment of the present invention in which a noise filter is constructed by combining a common mode choke coil and a capacitor. In these drawings, the coil device includes an insulating resin case 20,
Metal base 4 for heat radiation mounted on the lower surface side of the case 20
0, and a choke coil 2 and a capacitor 6 housed and arranged in the case 20.

The insulating resin case 20 is composed of a case body 21 which also functions as a casting frame, and a case lid 22 which fits into the case body 21. As shown in FIG. 6, the case main body 21 has a rectangular box shape having an open upper part having side surface portions 26 and bottom surface portions 23 forming four side surfaces, and a pair of outer wall portions (dams) on the inner bottom surface of the bottom surface portion 23. (Part) 24 and a pair of inner side wall parts (dam parts) 25 located inside thereof are integrally formed so as to form a casting material reservoir. A hole 27 is formed in the bottom surface portion 23 inside the pair of inner wall portions 25. On the inner bottom surface of the bottom surface portion 23 outside the outer wall portion 24,
An locking claw 28 is integrally formed as a locking part for locking the magnetic core 3 of the choke coil 2, and an input terminal holding part 30 holding an input terminal 29 and an output holding a pair of output terminals 31. The terminal holding portions 32 are integrally formed. In addition, as shown in FIG. 5 and FIG.
4, a slit hole 33 is formed in the bottom portion 23 on the outside of 4,
The core retainer 41 of the metal base 40 can be projected inside the case body 21. Further, on the outer surface of the side surface portion 26 of the case body 21, the tapered projection 3 that engages with the hole portion 43 of the mounting bending portion 42 of the metal base 40.
A plurality of pressing portions 35 that sandwich the bending portion 42 and the bent portion 42 are formed, and a tapered projection 38 that engages with the hole portion 37 of the engaging extension portion 36 of the case lid 22 is formed.

As shown in the exploded views of FIGS. 1 and 5, the magnetic core 3 of the choke coil 2 uses U-shaped core members 3a and 3b such as ferrite butted against each other. As shown in FIG. The leg portions of the U-shaped core members 3a and 3b are covered with an insulating cylinder 50 made of an insulating resin or the like, and the winding 5 around which the wire 4 is wound is wound on the insulating cylinder 50. The windings 5 are provided in two systems when forming a common mode choke coil or the like. In the example of FIG. 1, the U-shaped core member 3a,
The windings of two systems are obtained by connecting in series the winding portions that are respectively wound on both legs of 3b.

The heat-dissipating metal base 40 has a base main body portion 44 that is in close contact with the lower surface of the case main body 21, and a pair of core retainers 41 and a mounting folding portion 42 that are bent substantially perpendicularly thereto. In addition, a mounting portion 46 having a mounting hole 45 is further extended from the base main body portion 44 and is integrally formed. In addition, one of the core retainers 41
A ground terminal portion 47 is formed integrally therewith.

Case body 2 of the insulating resin case 20
First, the metal base 40 for heat radiation is attached to the lower surface of the unit 1. That is, the mounting bending portion 42 of the metal base 40 is inserted between the pressing portions 35 of the case body 21, and the hole portion 43 of the bending portion 42 is fitted into the tapered protrusion 34. As a result, the hole 27 in the bottom portion 23 of the case body 21 is closed by the metal base 40, and the bottom portion 23 and the metal base 40 are closed.
Of the base body portion 44, the pair of inner wall portions 25 and the side surface portion 2
A casting material pool 51 composed of 6 is formed, and a pair of core retainers 41 project into the case body 21.
In addition, the inner wall portion 25 and the outer wall portion 24 located outside of the inner wall portion 25.
A portion surrounded by the side surface portion 26 is an outer casting material reservoir 52 that receives a casting material such as an insulating resin overflowing from the casting material reservoir 51.

After mounting the metal base 40 on the case body 21, the choke coil 2 is placed in the case body 21. That is, the U-shaped core members 3a and 3b forming the magnetic core 3 of the choke coil 2 are held by a pair of core retainers 41 of the metal base 40, and are pressed upward by the locking claws 28 on the case body 21 side. Be stopped. Since the initial distance between the pair of core retainers 41 is set to be slightly shorter than the length of the U-shaped core members 3a and 3b butted together, the U-shaped core members 3a and 3b should be mounted between the pair of core retainers 41. Then, due to the elasticity of the core retainer 41, the U-shaped core members 3a and 3b are urged in a direction in which they abut against each other, so that the U-shaped core members 3a and 3b are joined together in a state where there is substantially no gap in the abutting surface. Therefore, an adhesive for holding the U-shaped core members 3a, 3b in a butted state, a jig for holding the U-shaped core members 3a, 3b until the adhesive is cured, and the like are unnecessary. The time required for those steps is also unnecessary.

The choke coil 2 is attached to the case body 21.
When placed inside, the lower surface of the magnetic core 3 is in contact with the upper end of the outer wall portion 24 as shown in FIG. The height of the magnetic core mounting portion of the inner wall portion 25 is set to be the same as that of the outer wall portion 24 or is set to be slightly lower than that of the outer wall portion 24 (however, in FIG. The case where it is slightly lower than the portion 24 is illustrated.). A thin portion 39 integrally formed in a strip shape on the bottom surface portion 23 of the case body 21 is interposed between the winding 5 of the choke coil 2 and the base body portion 44 of the metal base 40. The wire 5 does not come into direct contact with the base body portion 44, and the labor of providing an insulating sheet or the like as a separate component can be saved.

Choke coil 2 to the case body 21
After arranging, the casting material 10 such as an insulating resin is attached to the pair of inner wall portions 2
5 is cast in the casting material reservoir 51 on the inner side of 5 up to the height of the inner side wall portion 25. As a result, as shown in FIG. 7, only the winding 5 portion of the choke coil 2 is cast with the casting material 10 and fixed to the case body 21 and the metal base 40 for heat dissipation. Therefore, the winding 5 cast close to the base body 44
The generated heat is efficiently transmitted to the metal base 40 via the casting material 10 and is radiated and radiated, so that the temperature rise of the winding 5 can be prevented.

When the heights of the outer wall portion 24 and the inner wall portion 25 are the same, the casting material 10 may come into contact with the lower surface of the magnetic core 3 when casting is performed up to the height of the inner wall portion 25. However, there is no problem because the stress applied to the magnetic core 3 can be ignored if only the lower surface of the magnetic core 3 is contacted.

Then, one lead end of the winding 5 of the two systems of the choke coil 2 is connected to the input terminal 29 and the ground terminal portion 47 by soldering or the like, and the lead wire of the capacitor 6 is grounded to the input terminal 29 and the ground. The terminals 47 are connected by soldering or the like. The capacitor 6 is the case body 2
It is arranged in the inner space between the outer wall portion 24 and the side surface portion 26. Also, the other lead-out ends of the windings 5 of the two systems are connected to the output terminals 31 by soldering or the like. An external connection cord 61 is connected to the pair of output terminals 31 by soldering or the like.

After arranging and connecting the respective parts to the case body 21, the case lid 22 is fitted into the upper opening of the case body 21. That is, the tapered protrusion 38
The case main body 21 and the case lid body 22 are integrated by engaging the hole portion 37 of the extension portion 36 for engagement of the case lid body 22 with.

According to the first embodiment, the following effects can be obtained.

(1) Inner side wall portion 25 of the double wall portion formed on the case body 21 made of an insulating resin which also serves as a casting frame
Since the casting height of the casting material 10 is defined by the height of the inner wall 25, the height of the inner wall portion 25 is set to be the same as the lower surface of the magnetic core 3 of the choke coil 2 or lower than the lower surface of the magnetic core. By setting it low, it is possible to prevent the magnetic core 3 from being immersed in the casting material 10 and receiving stress (note that the stress applied to the magnetic core is small when the casting material is in contact with the lower surface of the magnetic core, which is acceptable). It is possible to prevent deterioration of the magnetic characteristics of the core and improve the performance of the choke coil 2.

(2) Even if the casting amount of the casting material 10 fluctuates and becomes excessive, the casting material 10 overflowing from the inner side wall portion 25 is the outer casting material between the inner side wall portion 25 and the outer side wall portion 24. Puddle 52
Since it enters and stops here, the casting material 10 can be prevented from accidentally flowing out. In addition, the inner wall portion 2 that affects the heat dissipation characteristics
The casting amount of the casting material reservoir 51 in 5 can be maintained at a constant amount determined by the height of the inner wall portion 25. Therefore, the heat radiation characteristics of the choke coil 2 can be stabilized, the casting amount can be easily controlled, and the casting workability can be improved.

(3) The winding 5 of the choke coil 2 and the metal base 40 are provided on the bottom portion 23 of the case body 21 which also functions as a casting frame.
The strip-shaped thin portion 39 is formed between the winding wire 5 and the base wire 44, and the winding 5 is close to the base body portion 44, but the winding wire 5 does not directly contact the base body portion 44 and is a separate component. As a result, it is possible to save the trouble of providing an insulating sheet or the like.

(4) By appropriately setting the position of the inner side wall portion 25, the casting range can be reduced to the necessary minimum, the amount of casting material can be reduced, and the cost can be reduced.

(5) The U-shaped core members 3a and 3b forming the magnetic core 3 can be held in a butted state by the elasticity of the core retainer 41 formed integrally with the metal base 40 for heat dissipation.
As a result, the adhesive application step and the step of holding the core members in a butted state until the adhesive is cured can be omitted, and the manufacturing and assembling can be facilitated.

(6) The case body 21 is integrally formed with the locking claws 28 for locking the magnetic core 3, so that the magnetic core 3 can be prevented from being lifted up during the casting operation, and the height direction of the magnetic core 3 can be prevented. Can be set so that the wire rod portion of the winding wire 5 is surely cast with the casting material 10.

(7) Since the ground terminal portion 47 is provided on one of the core holders 41 of the heat-dissipating metal base 40, the earth connection of the metal base 40 can be saved.

FIG. 8 shows a second embodiment of the present invention. In this case, an insulating plate 60 as an insulating member is provided between the rear end faces of the U-shaped core members 3a and 3b forming the magnetic core 3 of the choke coil 2 and the pair of core retainers 41 of the metal base 40 for heat dissipation.
Is interposed. Also in this case, the elasticity of the core retainer 41 urges the U-shaped core members 3a and 3b through the insulating plate 60 in a direction to abut against each other to form the magnetic core 3. Other configurations are the same as those in the first embodiment described above, and the same or corresponding parts are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the impedance of the choke coil 2 is reduced by insulating the magnetic core 3 formed by abutting the U-shaped core members 3a and 3b such as a ferrite core and the metal base 40 such as iron. The frequency characteristics could be improved.

FIG. 9 is a graph showing the frequency characteristics of the impedance of the choke coil 2, and the curve (a) shows the insulating plate 6.
In the case of the configuration of the first embodiment without 0, the curve (b) is the case of the configuration of the second embodiment with the insulating plate 60, and
It can be seen that the curve (b) corresponding to the example has a larger impedance in the high frequency region.

In each of the above embodiments, the case body 21
The outer wall portion 24 and the inner side wall portion 25 are provided inside the side surface portion 26 of the bottom surface portion 2 between the inner side wall portion 25 and the side surface portion 26.
When the structure in which no hole is formed in 3 is adopted, the side surface 2
6 can also serve as the outer wall portion (the outer wall portion 24 need not be provided inside the side surface portion 26).

The inner wall portion 25 may be higher than the outer wall portion 24. In this case, the magnetic core 3 is supported by hitting the upper end of the inner wall portion 25.

Further, as the magnetic core 3 of the choke coil 2, the U-U structure in which the U-shaped core members are butted is illustrated, but the U-shaped structure in which the U-shaped core member and the I-shaped core member are butted is butted.
I structure, E-E structure in which E type core members are butted against each other,
An E-I structure or the like in which an E-shaped core member and an I-shaped core member are butted against each other can be adopted according to the coil structure. It is also possible to use a rectangular endless core as the magnetic core.

Further, when the thin portion 39 is not provided on the bottom surface portion 23 of the case body 21, an insulating sheet is arranged between the base body portion 44 of the metal base 40 and the winding 5 of the choke coil 2. Then, the casting material 10 may be cast.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Let's do it.

[0050]

As described above, according to the coil device of the present invention, the height of the inner wall portion of the double wall portion formed in the casting frame for forming the casting material reservoir can be adjusted. The casting height of the casting material can be specified, and the height of the inner wall can be set at the same height as the bottom surface of the magnetic core of the coil, or by setting it lower than the bottom surface of the magnetic core. It is possible to avoid dipping in the magnetic core so that the stress of the casting material is not applied to the magnetic core. Therefore, it is possible to prevent the magnetic characteristics of the magnetic core from deteriorating and improve the performance of the coil.

Further, even if the casting amount of the casting material fluctuates and becomes excessive, the casting material overflowing from the inner wall portion enters between the inner wall portion and the outer wall portion and stops there. In addition to preventing inadvertent outflow, the amount of casting inside the inner side wall that affects the heat dissipation characteristics can be maintained at a fixed amount determined by the height of the inner side wall, and the heat dissipation characteristics of the coil can be stabilized. Management becomes easier and casting workability becomes better.

Further, by appropriately setting the position of the inner wall portion, it is possible to reduce the amount of the casting material by reducing the casting range of the casting material to the necessary minimum and to reduce the cost.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a coil device according to the present invention with a case lid removed.

FIG. 2 is a front view showing a cross section of a main part of the first embodiment.

FIG. 3 is a plan view showing a state in which the case cover of the first embodiment is attached.

FIG. 4 is a front view of the same.

FIG. 5 is an exploded sectional view of the first embodiment.

FIG. 6 is a plan view of a case body to which a metal base according to the first embodiment is attached.

FIG. 7 is an enlarged sectional view of a main part.

FIG. 8 is a front view showing a cross section of a main part of a second embodiment of the present invention.

FIG. 9 is a graph for explaining the effect of the second embodiment.

FIG. 10 is a front cross-sectional view showing a conventional coil device.

[Explanation of symbols]

 2 choke coil 3 magnetic core 3a, 3b U-shaped core member 4 wire material 5 winding 6 capacitor 10 casting material 20 insulating resin case 21 case body 22 case lid 23 bottom surface portion 24 outer wall portion 25 inner wall portion 26 side surface portion 27 Hole 28 Locking claw 29 Input terminal 31 Output terminal 40 Heat dissipation metal base 41 Core retainer 42 Bent section 44 Base body section 47 Ground terminal section 51, 52 Cast material pool 60 Insulation plate

Claims (5)

(57) [Claims] 1. A coil having a magnetic core provided with a winding wire, and a double wall portion composed of an inner wall portion and an outer wall portion forming a casting material reservoir, and a punch hole in the inner bottom surface portion of the inner wall portion. A casting frame having a casting frame and a base mounted on the lower surface of the casting frame to close the hole, and the coil is provided on the casting frame so that the winding is located inside the inner wall portion. At least a part of the inner wall portion is formed at the same height as the lower surface of the magnetic core or lower than the lower surface, and the winding is formed by a casting material cast inside the inner wall portion. A coil device fixed to the casting frame and the base. 2. The coil device according to claim 1, wherein the magnetic core is a butting structure of a plurality of core members, and the core members are biased in a butting direction by a core retainer integrally formed on the base. 3. The coil device according to claim 1, wherein the core retainer and the core member are insulated from each other. 4. The coil device according to claim 1, wherein a thin portion interposed between the winding and the base is integrally formed on a bottom portion of the casting frame. 5. The coil device according to claim 1, 2, 3 or 4, wherein a locking portion for locking the magnetic core is integrally formed on the casting frame.