JP2003173915A - Small-sized choke coil with pot rivet type core constituted by packing, pressurizing, molding, and baking fine ferrite powder in metal mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized choke coil with pot rivet type core having fitted projecting sections or fitting recessed sections. <P>SOLUTION: This small-sized choke coil has a pot type core 10 composed of a top wall 101 and a side wall 103 integrally constituted with the wall 101, and a rivet type core 20 composed of a bottom plate 201 and a magnetic core section 204 integrally erected on the central part of the plate 201. A clearance G for magnetic path is formed by facing the upper end face of the magnetic core section 204 to the top wall 101 of the core 10, and the cores 10 and 20 are joined and fixed to each other. In addition, the fitted projecting sections 105 or fitting recessed sections 205 are formed one by one on the facing opened end faces of the side wall 103, and the fitting recessed sections 205 or fitted projecting sections 105 are formed one by one on the top faces of the facing two edges of the bottom plate 201. Moreover, the fine ferrite powder joining and fixing the cores 10 and 20 to each other is packed, pressurized, molded, and baked in a metal mold. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pot rivet type core small choke coil formed by filling a metal mold with a ferrite fine powder, press-molding and firing, and more particularly to a pot. The present invention relates to a pot rivet-type core small choke coil formed by filling a metal mold with a ferrite fine powder having a fitting convex portion or a concave portion to be fitted into a mold core and a rivet mold core, press-molding and firing. 2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 3 is a partial cross-sectional exploded perspective view of a conventional example, and FIG.
FIG. 3 is a view showing a misaligned joining state between a pot type core and a rivet type core. Reference numeral 10 denotes a pot type core made of ferrite. Reference numeral 101 denotes a top wall of the square pot-shaped core 10. Reference numeral 103 denotes a side wall of the pot type core 10. A notch 104 is formed at the lower part of the corner where the side walls 103 adjacent to each other intersect. [0003] The pot-type core 10 is formed by filling a metal mold with ferrite fine powder, press-molding, and then firing at a high temperature. 3 indicates a coil. The coil 3 is formed by spirally winding and deforming a round or square electric wire. Reference numeral 31 denotes a coil terminal. The coil 3 is formed by winding the number of turns corresponding to the required inductance. 4 is a terminal. The terminal 4 has a mounting section 44 having a U-shaped cross section, and a mounting section 44.
And a locking projection 46 formed integrally with the coil connecting portion 45 and protruding from the upper surface of the coil connecting portion 45. Reference numeral 20 denotes a rivet-type core made of ferrite. The rivet-type core 20 has a square bottom plate 201 and a magnetic core portion 20 that is integrally formed with the bottom plate 201 and is erected at the center thereof.
4 The height of the magnetic core portion 204 is designed to be slightly lower than the height of the inner surface of the side wall 103 of the pot type core 10, and the height between the inner surface of the top wall 101 of the pot type core and the end surface of the magnetic core portion 204 of the rivet type core is set. A gap G of the magnetic path is formed therebetween.
The gap G is adjusted to set the inductance of the coil. Reference numeral 202 denotes a fitting thin portion formed at an intermediate portion between two opposing sides of the bottom plate 201, and the mounting portion 44 of the terminal 4 having a U-shaped cross section is fitted and fixed. Reference numeral 203 denotes a terminal mounting surface, which is a region provided with a step lower than the surface of the bottom plate 201 by the thickness corresponding to the thickness of the terminal 4. [0005] The rivet core 20 is also filled with a ferrite fine powder in a metal mold, press-molded, and then fired at a high temperature to form the magnetic core 204 and the bottom plate 201 integrally. The order of assembling the choke coil using the above components will be described. A pot type core 10, a coil 3, a terminal 4, and a rivet type core 20 are prepared. Step The terminal 4 is fitted and fixed to the terminal mounting surface 203 and the fitting thin portion 202 of the rivet type core 20. Step 3 The coil 3 is attached to the magnetic core 204 of the rivet-type core 20.
Is fitted. Next, the coil end portion 31 of the coil 3 is soldered to the coil connection portion 45 of the terminal 4. At this time, the coil end portion 31 is temporarily fixed to the locking projection 46 formed on the upper surface of the coil connection portion 45. Step An epoxy-based synthetic resin adhesive is applied to the peripheral edge of the opening of the pot type core 10 and the surface of the bottom plate 201 of the rivet type core 20. Step With the gap G formed between the top wall 101 of the pot-type core 10 and the end face of the magnetic core 204 of the rivet-type core 20, the two are joined and fixed. At the time of this joining and fixing, the pot type core 10 and the rivet type core 20, which are members to be assembled, are each set in a dedicated jig, and the joining and fixing are performed with the mutual alignment and positioning. [0007] With the above, the assembly of the choke coil is completed. The dimensions of the pot rivet type core surface mount choke coil are, for example, the height of the side wall 103 of the pot type core 10 is 3.8 mm, the height of the notch 104 is 1 mm, and the thickness of the metal sheet material of the terminal 4. The height is 0.4mm,
The thickness of the bottom plate 201 of the rivet type core 20 is 1.7 mm,
The step from the surface of the bottom plate 201 is as small as about 0.4 mm. As described above, a pot rivet-type core formed by filling a metal mold with a ferrite fine powder under pressure and firing, and a pot-type core 10 and a rivet-type core forming a small choke coil. Each of the cores 20 is manufactured by filling a metal mold with ferrite fine powder, press-molding, and firing at a high temperature. Since the processing including the pressing, molding and firing steps generally has low processing accuracy, the finished pot type core 10 and the rivet type core 20 do not sufficiently satisfy the design accuracy. Inevitably, slight deformation and warpage remain. In addition, the shape and dimensions of the choke coil are very small, approximately several mm. That is, if the minute pot type core 10 and the rivet type core 20 of this minute choke coil are deformed and warped, the position between the pot type core 10 and the rivet type core 20 is reduced when performing the work of assembling them. It is difficult to perform the alignment, and there is a high possibility that the two are fixedly joined in a state where a positional shift occurs as shown in FIG. To prevent this displacement, as described above, a dedicated jig having a complicated shape and structure for aligning and positioning the pot type core 10 and the rivet type core 20 with each other is prepared and used. The necessity of a special jig for assembling the choke coil means that the cost of preparing the special jig is high, and the pot type core 10 and the rivet type core 20, which are members to be assembled, are used as special jigs. This means that the number of setting steps increases. The process of setting the pot-type core 10 and the rivet-type core 20 in a dedicated jig is not an easy process because these members are minute members. Even when the pot-type core 10 and the rivet-type core 20 are aligned and joined by using a special jig, there is a variation in accuracy in the special jig itself, and the alignment and positioning between the two are completely properly performed. It cannot be implemented. The present invention uses a special jig for the pot rivet-type core 20 and the rivet-type core 20 of a small choke coil formed by filling a metal mold with a ferrite fine powder, press-molding and firing. An object of the present invention is to provide a pot rivet-type core small choke coil constituted by filling a metal mold with pressure, molding and firing ferrite fine powder, which solves the above-described problem of properly aligning and positioning without any need. Means for Solving the Problems Top wall 101 and top wall 1
And a rivet-type core 20 including a bottom plate 201 and a magnetic core 204 erected at the center of the bottom plate 201 integrally with the bottom plate 201. The upper end surface of the magnetic core portion 204 is made to closely approach the top wall 101 of the pot type core 10 to form a gap G in the magnetic path, and the ferrite fine powder for joining and fixing the pot type core 10 and the rivet type core 20 is molded. In the pot rivet-type core small choke coil formed by filling pressure molding and firing, one fitting protrusion 105 or one fitting recess 205 is formed on each of the opening end faces of the side wall 103 facing each other, and the bottom plate 2 is formed.
01 are formed one by one on the upper surface of the two opposing sides, and the pot type core 10 and the rivet are formed in a state where the fitting projection and the fitting recess are fitted to each other. A pot rivet-type core small choke coil was formed by filling a metal mold with a ferrite fine powder characterized by being fixedly joined to the mold core 20 and then firing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is an exploded perspective view of the embodiment, and FIG. 2 is a view showing a joint state between a pot type core and a rivet type core. Reference numeral 10 denotes a pot type core made of ferrite. Reference numeral 101 denotes a top wall of the square pot-shaped core 10. Reference numeral 103 denotes a side wall of the pot type core 10. A notch 104 is formed at the lower part of the corner where the side walls 103 adjacent to each other intersect. The fitting protrusions 105 are formed one by one on the opening end faces of the side wall 103 facing each other. The fitting projection 105 can be used as the fitting recess 205. The pot-shaped core 10 is formed by filling a metal mold with ferrite fine powder, press-molding, and then firing at a high temperature. 3 indicates a coil. The coil 3 is formed by spirally winding and deforming a round or square electric wire. Reference numeral 31 denotes a coil terminal. The coil 3 is formed by winding the number of turns corresponding to the required inductance. 4 is a terminal. The terminal 4 has a mounting section 44 having a U-shaped cross section, and a mounting section 44.
And a locking projection 46 formed on the upper surface of the coil connection portion 45. Reference numeral 20 denotes a rivet-type core made of ferrite. The rivet-type core 20 has a square bottom plate 201 and a magnetic core portion 20 that is integrally formed with the bottom plate 201 and is erected at the center thereof.
4 The height of the magnetic core portion 204 is designed to be slightly lower than the height of the inner surface of the side wall 103 of the pot type core 10, and the inner surface of the top wall 101 of the pot type core and the upper end surface of the magnetic core portion 204 of the rivet type core To form a gap G of the magnetic path. The gap G is adjusted to set the inductance of the coil. Reference numeral 202 denotes a fitting thin portion formed at an intermediate portion between two opposing sides of the bottom plate 201, and the mounting portion 44 of the terminal 4 having a U-shaped cross section is fitted and fixed. Reference numeral 203 denotes a terminal mounting surface, which is a region provided with a step lower than the surface of the bottom plate 201 by the thickness corresponding to the thickness of the terminal 4.
Then, one fitting recess 205 is formed on the upper surface of two sides of the bottom plate 201 facing each other. Fitting recess 20
5 can be used as the fitting projection 105. The rivet-type core 20 is also filled with a ferrite fine powder in a mold, molded under pressure, and then fired at a high temperature to form the magnetic core 204 and the bottom plate 201 integrally. The order of assembling the choke coil using the above components will be described. A pot type core 10, a coil 3, a terminal 4, and a rivet type core 20 are prepared. Step The terminal 4 is fitted and fixed to the terminal mounting surface 203 and the fitting thin portion 202 of the rivet type core 20. Step 3 The coil 3 is attached to the magnetic core 204 of the rivet-type core 20.
Is fitted. Next, the coil end portion 31 of the coil 3 is soldered to the coil connection portion 45 of the terminal 4. At this time, the coil end portion 31 is temporarily fixed to the locking projection 46 formed on the upper surface of the coil connection portion 45. Step An epoxy-based synthetic resin adhesive is applied to the peripheral edge of the opening of the pot-shaped core 10 and the upper peripheral surface of the bottom plate 201 of the rivet-shaped core 20. Step Opposite Side Walls 103 of Pot-Type Core 10
The fitting convex portion 105 formed on the opening end face of
In a state in which the fitting protrusions 105 and the fitting recesses 205 are fitted to each other so as to correspond to the fitting recesses 205 formed on the upper surface of the two opposing sides of the bottom plate 201 of the rivet type core 20,
The pot type core 10 and the rivet type core 20 are joined and fixed. Thus, the assembly of the choke coil is completed. As described above, when two separate members are aligned with each other, a fitting protrusion or a fitting recess is formed on both members to fit the fitting protrusion. Fitting and positioning the mating recesses with each other requires a relatively large external dimension.
It is generally well known in the alignment positioning of members.
However, it is also preferable to form a fitting protrusion or a fitting recess in a small member with low design accuracy formed by filling a metal mold with a ferrite fine powder, pressing and molding, and firing, and positioning the members relative to each other. The probability of obtaining the results is small and has not been implemented to date, and as described above, depends on the use of a dedicated jig having a complicated shape and structure for aligning and positioning the pot type core 10 and the rivet type core 20 with each other. Was. However, according to the present invention, as described in the steps, the side walls 1 of the pot-shaped core 10 facing each other are formed.
The fitting projections 105 formed on the opening end face of the bottom plate 201 of the rivet-shaped core 20 are respectively opposed to each other.
By a simple operation of joining and fixing the pot type core 10 and the rivet type core 20 in a state corresponding to the fitting concave portion 205 formed on the upper surface of the side, the two can be connected without using a special jig. It could be properly aligned and positioned and fixed. That is, the burden of properly designing and manufacturing a mold for filling and press-molding ferrite fine powder is increased, and the completed outer shape of the pot-type core 10 and the rivet-type core 20 causes the fitting protrusion or the fitting recess to be formed. Although there was a concern that the design accuracy would be further reduced due to the complexity of the formed portions, nevertheless, the two could be properly aligned, positioned and fixed without using a dedicated jig.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of an embodiment. FIG. 2 is a diagram showing a joint state between a pot type core and a rivet type core. FIG. 3 is an exploded perspective view, partially in section, of a conventional example. FIG. 4 is a diagram showing a misaligned joining state between a pot type core and a rivet type core. DESCRIPTION OF SYMBOLS 10 Pot-type core 101 Top wall 103 Side wall 104 Notch 105 Fitting protrusion 20 Rivet-type core 201 Bottom plate 202 Fitting thin portion 203 Terminal mounting surface 204 Magnetic core 205 Fitting recess 3 Coil 31 Coil end 4 Terminal 44 Attachment 45 Coil connection 46 Locking projection G Gap

Claims (1)

Claims: 1. A magnetic core having a pot-shaped core having a top wall and a side wall integrally formed with the top wall, and a bottom plate and a magnetic core portion standing upright at the center of the bottom plate integrally with the bottom plate. A ferrite fine powder for joining and fixing the pot type core and the rivet type core by forming a gap in the magnetic path by making the upper end surface of the magnetic core portion close to and facing the top wall of the pot type core, A pot rivet-type core small choke coil formed by filling, pressing, molding and firing into a mold is formed with one fitting projection or one fitting recess on each of the opposed open end faces of the side wall, and the bottom plate faces each other. A fitting recess or a fitting protrusion is formed one by one on the upper surface of the two sides, and the pot type core and the rivet type core are joined and fixed in a state where the fitting protrusion and the fitting recess are fitted to each other. Filling mold with ferrite fine powder Type, pot rivet constituted by firing core compact choke coil.