Inductance element and case

An inductance element and a case; the inductance element, comprising a winding type magnetic core having a hollow part formed by winding a magnetic ribbon thereon and a lead having a cross sectional dimension smaller than the inner diameter of the hollow part of the magnetic core and passing the hollow part, wherein a clearance is provided between the magnetic core and the lead; the case, comprising a plurality of members combined with each other, wherein the members are connected to each other in a surface including one or more case ridge lines.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to an inductance element such as a choke coil and to a case that contains the inductance element.

2. Background Art

An inductance element disclosed in JP 08-172019 A or the like has been known as one in which a magnetic ribbon such as an iron base amorphous alloy ribbon is wound around on a core having a hollow part, a lead is passed through the core, and the wound magnetic core is contained in a case.

The inductance element is constructed by a toroidal magnetic core having a magnetic alloy foil strip wound therearound, a case that contains the magnetic core, and a lead which is passed through the magnetic core and the case, and has a structure in which the lead is fixed to a body to be connected which is the surface mounting of a circuit board or the like.

This inductance element thinks of exfoliation prevention from said a body, and a front edge department of an above lead line consists of it to become parallel to the surface of a body.

Also, in the inductance element, it is suitable that a maximum length of a cross section of the lead is 0.8 times to 1.2 times the inner diameter of the magnetic core. In the inductance element, with a state in which the lead is inserted into the toroidal magnetic core, the magnetic core is subjected to heat treatment to produce distortion, thereby fixing the lead to the toroidal magnetic core.

Also, in the above-mentioned publication, it is noted that if a clearance is present between the case and the magnetic core, the magnetic core moves, so that it is necessary to fix the case and the magnetic core using a grease, an adhesive, a resin, or the like.

However, in the above-mentioned conventional technique, consideration is not given to vibration resulting from interaction between a current flowing through the lead and the magnetic core, vibration of the case caused due to the vibration, noises resulting from those vibrations, or the like.

Therefore, in a magnetic wound core around which a magnetic ribbon made of, for example, iron base amorphous metal is wound around on a core, when a current is made to flow through a lead, the magnetic core is excited. Magnetostriction is caused by the excitation, which reliably causes vibration. When the vibration thus caused is in an audio frequency range, there is the case where the vibration is propagated as noise throughout the surrounding area. In addition, when the inductance element is bonded to an object to be bonded such as a circuit board, there is the case where parts in the periphery of the inductance element are vibrated, thereby deteriorating operating characteristics of the object to be bonded.

Thus, consideration has been on the idea of containing the magnetic core in the case to obtain a hermetically sealed structure, thereby cutting off the noise caused in the magnetic core to reduce the outside noise leaked of the case, however, when the inductance element in which the lead is passed through the magnetic core is contained in the case, it is required to provide a manufacturing order in which the case is formed in advance so as to be composed of a plurality of members and the members are combined after the core is contained in the case.

Such bonding of the members is generally conducted by a method using an adhesive, ultrasonic bonding, or the like. Further, the larger the area of a bonding region, the more advantageous the above-mentioned bonding method is, in terms of bonding strengths of the respective members in the bonding.

The area of the bonding region is widened as thicknesses of the members composing the case increase. However, there is a problem in that when the thicknesses of the members are increased, a size of the case is accordingly increased.

The present invention has been made in view of such problems of the conventional techniques. Therefore, an object of the present invention is to, in the inductance element which is provided with the winding type magnetic core and the lead, reduce vibration resulting from a current flowing through the lead or noise leaked to the outside of the element.

Also, another object of the present invention is to, in the inductance element, increase the area of the bonding region of the members composing the case without increasing the size of the case that contains the element.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problem, the following means is employed in the present invention. In other words, according to the present invention, there is provided an inductance element comprising: a magnetic wound core having a hollow part, which is formed by winding a magnetic ribbon therearound; and a lead that has a cross sectional dimension smaller than the inner diameter of the hollow part of the magnetic core and is passed through the hollow part, in which a clearance is provided between the magnetic core and the lead.

By providing the clearance between the winding type magnetic core and the lead, the vibration is not propagated between the magnetic core and the lead, thereby reducing noise.

Also, it is preferable that the inductance element further comprise a case with a hermetically sealed structure that contains the magnetic core and that the lead be passed through the case in a hermetic sealing state. With such a case having the hermetically sealed structure, noise is further reduced.

Also, it is preferable that the case have an accommodation space adaptable to an appearance shape of the winding type magnetic core and a clearance be provided between an inner surface of the accommodation space and an outer surface of the magnetic core. According to the structure, the vibration of the magnetic core is not propagated to the case, thereby reducing noise.

Also, according to the present invention, there is provided an inductance element including: a cylindrical magnetic core having a hollow part; a case for hermetically sealing the magnetic core, which has a cylindrical part composing a hollow part that contains the magnetic core and side wall members made of metal, the side wall members being opposed to side surfaces of both ends of the magnetic core in both ends of the cylindrical part and composing cover parts for the hollow part, and which hermetically seals the magnetic core; and a lead that is passed through the hollow part of the magnetic core both ends of which are connected with the respective side wall members, the side wall members have edge parts extended in an outside direction of the cylindrical part in both the ends of the above-mentioned cylindrical part, the edge parts compose conductive contact parts to an object to be bonded outside of the cylindrical part.

It is preferable that an iron base amorphous alloy ribbon be used as the above-mentioned magnetic ribbon. For the iron base amorphous alloy ribbon, iron base amorphous metals such as Fe—B, Fe—B—C, Fe—B—Si, Fe—Si—C, Fe—B—Si—Cr, Fe—Co—B—Si, or Fe—Ni—Mo—B can be given as an example.

Among the above-mentioned iron base amorphous metals, more preferably, FexSiyBzMwcan be given as an example. Here, X ranges from 50 to 85, Y ranges from 1 to 15, and Z ranges from 5 to 25 (X, Y, and Z respectively indicate atomic %). In addition, M represents one kind of metal such as Co, Mn, C, Al, or P or a combination of two or more kinds of those metals and metal with W=0 to 5 atomic % can be given as an example.

The iron base amorphous metal is a material that causes large magnetostriction at the time of excitation to readily cause vibration is easy to generate, though by adopting the above-mentioned structure, the vibration is not propagated, so that noise can be reduced.

Further, in order to solve the above-mentioned another problem, the following means is employed in the present invention. That is, according to the present invention, there is provided an inductance element including: a cylindrical magnetic core having a hollow part; a case that has a rectangular cross sectional outside shape and contains the magnetic core; and a lead that is passed through the hollow part of the magnetic core and the case, and an above case has a plurality of members and the members are bonded to each other in a surface including at least one ridge line of the case.

Also, according to the present invention, there is provided a case that has a rectangular cross sectional outside shape and contains an element including a cylindrical magnetic core having a hollow part and a lead that is passed through the cylindrical magnetic core, comprising two members bonded to each other in a surface including at least one ridge line of the case.

As described above, when the two members are bonded to each other, the bonding distance of a bonding region can be increased without increasing the dimensions of the case.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an inductance element and a case according to embodiment modes of the present invention will be described with reference to the drawings.

An inductance element according to a first embodiment mode of the present invention will be described with reference toFIGS. 1 and 2.

FIG. 1shows a structure of the inductance element andFIG. 2shows measurements of a noise generation amount characteristic in the inductance element. As shown inFIG. 1, the inductance element has a structure in which a lead2is passed through a cylindrical core1having a hollow part3. A support member for fixing the core1and the lead2is not provided, so that the core1is rotatable and slidable with respect to the lead2.

The core1is manufactured by winding an iron base amorphous magnetic alloy foil strip produced by Allied Signal Inc. USA, one side surface of which is coated with a fine powder of Sb2O5, around on a roller having a diameter of 1.8 mm, and dimensions of the core thus manufactured are 1.8 mm in inner diameter (diameter, same for the following), 8.2 mm in outer diameter (diameter, same for the following), and 15 mm in length.

A wound portion of the core1is hardened by spark welding. Then, the core1is subjected to heat treatment for 2 hours at a temperature which is equal to or larger than a Curie temperature and equal to or smaller than a crystallization temperature, more specifically, at 435° C.

The lead2having a diameter of 1.8 mm is inserted into the hollow part3of the core1to produce an element L1. In addition, a lead2having a diameter of 1.6 mm is inserted into a core1which has the same shape as that of the above-mentioned core1and is made of the same material as that of the above-mentioned core1to produce an element L2. Further, a lead2having a diameter of 1.0 mm is inserted into a core1which has the same shape as that of the above-mentioned core1and is made of the same material as that of the above-mentioned core1to produce an element L3.

Therefore, in the element L1, there is no clearance between an inner wall3A of the hollow part3and an outer surface2A of the lead2. Further, in the elements L2and L3, clearances of 0.1 mm and 0.4 mm are respectively created between the inner wall3A of the hollow part3and the outer surface2A of the lead2.

A current is supplied to the three kinds of inductance elements under the following measurement condition described in Table 1 below and sound production quantities from the elements are measured by using a microphone.

TABLE 1Supply Current (A)4.5Duty Factor (%)50Slow Rate (V/μs)50Measurement Frequency [Hz]100 to 1400Distance to Microphone (cm)10

FIG. 2shows measurements. InFIG. 2, the abscissa indicates a measurement frequency of a supply current and the ordinate indicates a noise generation amount. In addition, inFIG. 2, polygonal line graphs of inserted lead Ö of 1.8, 1.6, and 1.0 show measurements with respect to the element L1in which the lead2has the diameter of 1.8 mm, the element L2in which the lead2has the diameter of 1.6 mm, and the element L3in which the lead2has the diameter of 1.0 mm.

As is apparent fromFIG. 2, the noise generation amount is smaller in the element in which the diameter of the lead2is smaller than the inner diameter (1.8 mm) of the core1. For example, at a frequency of 1400 Hz, the noise generation amount is reduced to 31 (dB) in both the element L2and the element L3as compared with the noise generation amount of 33 (dB) in the element L1.

An inductance element according to a second embodiment mode of the present invention will be described with reference toFIGS. 3 to 6.FIG. 3is an exploded view showing structural elements of the inductance element.FIG. 4is sectional views showing a structure of the inductance element.FIG. 5shows measurements of a noise generation amount characteristic in the inductance element, andFIG. 6is a sectional view showing a structure of an inductance element according to a modified example of this embodiment mode.

In the above-mentioned first embodiment mode, the noise generation amount characteristic of the inductance element in which the lead2has been passed through the core1having the hollow part3has been described. In this embodiment mode, an inductance element provided with a case4that has a hermetically sealed structure and contains the core1described in the first embodiment mode will be described. In this embodiment mode, a structure other than the case4is the same as that in the first embodiment mode. Accordingly, the same reference symbols are given to the same structural elements and the description thereof is omitted here.

As shown inFIG. 3, the inductance element has a structure in which an element having the same structure as that of the inductance element of the first embodiment mode which is composed of the core1and the lead2is hermetically sealed in a case4made of a PPS (polyphenylene sulfide) resin and side wall members9(electrodes). The case4is composed of four sidewalls4A to4D and two end surfaces each having an opening part6.

The element composed of the core1and the lead2is inserted into a hollow part5of the case4. Then, the side wall members9and the lead2are soldered at both end portions of the case4to fix the case4and the side wall members9with an adhesive to manufacture the inductance element according to this embodiment mode.

Here, the side wall members9each have a bottom wall that covers the end surface of the case4, and four side walls9A to9D which are bent with respect to the bottom wall and provided perpendicular to the bottom wall. The four side walls9A to9D are bonded to the side walls4A to4D of the case4, respectively with an adhesive to hermetically seal the case4.

Also, the side walls9A to9D form conductive contact portions on the side walls4A to4D of the case4. Therefore, the inductance element is constructed which is capable of being mounted through an arbitrary surface of the side walls4A to4D.

Note that, in order to facilitate soldering, an opening9E through which the lead2is passed may be provided near the center of the bottom wall of the case4.

Sectional views of the inductance element are shown inFIG. 4. As shown inFIG. 4, the case4made of a PPS resin has the hollow part5and the opening parts6. The core1through which the lead2is passed is accommodated in the hollow part5through the opening part6.

Further, in the case4, the opening parts6are covered with a pair of side wall members9from both sides thereof. Upon the covering, the side wall members9and the lead2are soldered by solder10.

Furthermore, the side wall members9are bonded to the case4with adhesives11. As a result, the inductance element composed of the core1and the lead2is hermetically sealed by the case4and the side wall members9.

Note that, inFIG. 4, the inner diameter of the hollow part5of the case4is 11.5 mm, the outer dimension of the core1is 11 mm, the inner diameter of the hollow part3of the core1is 1.8 mm, and the outer dimension of the lead2is 1.6 mm.

FIG. 5shows measurements with respect to the inductance element shown inFIG. 3. InFIG. 5, a polygonal line graph indicating that “the hermetically sealed structure is used” shows a noise generation amount characteristic in the inductance element having the structure shown inFIG. 4.

Also, inFIG. 5, a polygonal line graph indicating that “no hermetically sealed structure is used” shows a noise generation amount characteristic in an inductance element having the structure in which the adhesives11are not used in the structure shown inFIG. 4, so that the side wall members9and the case4are not bonded.

As shown inFIG. 5, by employing the case having the hermetically sealed structure for the inductance element shown inFIG. 4to suppress vibration of the lead2, a reduction in noise generation amount can be recognized. In this example, at a frequency of 1400 (Hz) the noise generation amount is reduced from about 36.5 (dB) to 27.5 (dB).

As described above, in this embodiment mode, the element is inserted through the opening part6of the case4having the hollow part5to manufacture the inductance element having the hermetically sealed structure. However, the embodiment of the present invention is not limited to such a structure and a procedure.

FIG. 6shows an example in which left and right parts4X and4Y are combined to assemble the case4. The case4is produced by bonding the bonding regions of the left and right parts4X and4Y with the adhesive11. According to such a structure, the inner diameter of the opening part6of the case4can be reduced up to the order of the outer diameter of the lead2, so that a hermetic sealing effect can be further improved.

Also, in the present invention, the case4may be composed of parts divided in a cross section parallel to the longitudinal direction. In addition, the case4may be composed of a cylindrical part having an opening end in which a side wall is provided perpendicular to a bottom of the case4and a cover part that hermetically seals the opening end of the cylindrical part. Further, the parts4X and4Y composing the case may be bonded to each other by ultrasonic bonding without using an adhesive. Furthermore, the case4may be made of a resin other than PPS or a material other than the resin.

As shown inFIG. 3, the side wall members9completely cover both end surfaces of the case in the above-mentioned embodiment mode. However, the embodiment of the present invention is not limited to such a structure. For example, if the sidewall member (electrode)9has an electrode member with dimensions capable of covering the opening part6of the case4and any one of contact portions (9A to9D) extended to any one of the case side surfaces (4A to4D) a surface-mount type inductance element can be constructed.

In the above-mentioned embodiment mode, the example in which the core1and the lead2have been hermetically sealed with the side wall members9in the surface-mount type inductance element has been described. However, the embodiment of the present invention is not limited to such a structure. For example, even in an inductance element having a structure in which end portions of the case4are hermetically sealed with a resin and the lead2is passed through the case in a hermetically sealed state, the noise generation amount can be reduced.

In this embodiment mode, two kinds of inductance elements different from each other in the outer diameter of a core1will be manufactured without providing the hermetically sealed structure using adhesives11in the inductance element shown inFIGS. 3 and 4. Then, the degree of influence of noise resulting from contact between the core1and a case4is measured.

That is, in this embodiment, an inductance element having the core1with an outer dimension of 8.2 mm and a length of 15 mm is inserted into the case4having an opening part6which is 8.2 mm in inner diameter to produce an element L4, and an element L5which is produced with the outer diameter of the core being 7.6 mm.

In this case, in the element L4, the outer surface of the core1is closely in contact with the inner surface of the hollow part5of the case4. On the other hand, in the element L5, a clearance of 0.3 mm is present between the outer surface of the core1and the inner surface of the hollow part5of the case4.

With respect to such two elements, the sound production quantities of the two elements are measured by the same procedure as that in the first embodiment mode.

FIG. 7shows measurements of the sound production quantities in such two elements. InFIG. 7, a graph of phi 8.2-phi 1.8–15 which is indicated by a symbol ( ) shows a measurement in the element L4in which the core1is closely in contact with the case4. On the other hand, a graph of phi 7.6-phi 1.8–15 which is indicated by a symbol ( ) shows a measurement in the element L5in which the clearance is present between the core1and the case4.

As shown inFIG. 7, over the whole measurement frequency range, the noise generation amount in the element L5with the clearance is reduced by about 15 (dB) as compared with that in the element L4with no clearance.

Next, a case according to the present invention will be described. The case according to the present invention is constructed based on the following embodiment mode in addition to the above-mentioned embodiment modes 1 to 3.

In this embodiment mode,FIG. 8is a perspective view of an inductance element according to this embodiment mode. In addition,FIG. 9is an exploded view showing a member14A and a member14B which compose the case4shown inFIG. 8. The inductance element is provided with a core1having the same shape as that of the cylindrical core1shown inFIG. 1and is composed of a lead2that is passed through the core1and the case4that contains the core1as shown inFIG. 8.

The inductance element is produced according to the following procedure. First, amorphous metal is wound to form the core1having the hollow part. Then, the lead2is passed through the core1to obtain the inductance element.

The case4is formed such that its appearance is of a rectangular parallelepiped shape, and has an accommodation space for accommodating the core1in an inner portion. As shown inFIG. 9, the case4is composed of the member14A and the member14B which are divided along ridge lines12. In addition, opening parts6are formed in the end surfaces of the case4. The member14A and the member14B divide the opening parts6along diagonal lines in the end surfaces.

As a material of the case4, for example, a synthetic resin such as PPS (polyphenylene sulfide) can be used.

In the case4, the inductance element through which the lead2covers contained in one member14A, and the other member14B covers the member14A. An adhesive is applied in advance onto bonding surfaces of the members14A and14B, and the members14A and14B are bonded to each other with the adhesive.

FIG. 10is a sectional view of the member14A. In addition,FIG. 11is a sectional view of a comparative example of the case4.

As shown inFIG. 10, in the member14A (and the member14B), the bonding region is formed within a surface including the ridge lines12located on a rectangular shape cross section of the case perpendicular to the paper surface. On the other hand, in the comparative example shown inFIG. 11, the bonding region is formed within a surface which does not include the ridge lines12of the case.

Therefore, in the comparative example, the bonding surface is formed in a thin portion of the case, so that a bonding distance is short. On the other hand, in the member14A, along bonding distance can be ensured, so that an area of the bonding region can be increased.

In the above-mentioned fourth embodiment mode, the members14A and14B are bonded within the surface including two ridge lines12which are present at the diagonal positions of the case4having the rectangular parallelepiped shape. However, the embodiment of the present invention is not limited to such a structure.

For example, in the case of adopting such a manufacturing procedure in which the core1is contained in the case4and then the lead2is passed therethrough, it is unnecessary to divide the opening part6for the members14A and14B.FIGS. 12 to 14are perspective views each showing such a structure.

In a case15shown inFIG. 12, the position of the opening part6is the same as that in the above-mentioned fourth embodiment mode. Note that the bonding region in which the member14A and the member14B are bonded is set at a position which includes a ridge line12of a rectangular parallelepiped and does not divide the opening part6. As a result, the opening part6is provided in the member14A.

Also, in a case16shown inFIG. 13, the position of the bonding region is the same as that in the above-mentioned embodiment mode. However, the opening part6is located not on the diagonal line of end surfaces (the center of the end surfaces) of the rectangular parallelepiped but in the member14A. Note that, in the case where the opening part6is not located in the center of the end surfaces as described above, it is necessary to bend the lead2upon insertion into the core1.

Also, a case17shown inFIG. 14is composed of members14A and14B composing the rectangular parallelepiped member and side wall members (electrodes)9. In this case, each of the side wall members9is not divided along the diagonal line, and an opening9E is not divided in the bonding region. Thus, in any of the structures described above, the bonding distance between the members14A and14B can be lengthened.

In the above-mentioned embodiment mode, the members14A and14B are boned to each other with the adhesive. However, the embodiment of the present invention is not limited to such a structure. For example, the member14A and the member14B may be bonded to each other by ultrasonic bonding.

Note that, in any of the above-mentioned cases, it is preferable to hermetically seal the core1using the case4in view of noise insulation.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, in an inductance element provided with a magnetic wound core and a lead, vibration and noise leaked to the outside of the element can be reduced.

Also, according to the present invention, in a case that contains the magnetic core, an area of a bonding region of members composing the case can be increased without increasing the size of the case, whereby an increase in bulk of the inductance element can be prevented.