Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2001-10-09
2003-02-18
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S083000, C336S192000
Reexamination Certificate
active
06522233
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coil apparatus in an inductor, a transformer or the like such as a choke coil which is utilized in a switching power supply and the like.
2. Description of the Related Art
A one-turn coil constituted of a metal plate is used as a choke coil or a low-voltage side coil of a transformer in a switching power supply or the like with a large current capacity in the prior art. For instance, Japanese Unexamined Patent Publication No. 97054-1996 discloses a transformer constituted by utilizing such a metal plate. This transformer assumes a structure achieved by laminating a high-voltage side coil and a low-voltage side coil via an insulating case formed in a plate shape and housing the high-voltage side coil and the low-voltage side coil in a case-like insulating member.
In the coil apparatus in the prior art described above, various members must be provided for insulation, presenting a problem in that the number of required parts is bound to be large.
In addition, the coil apparatus disclosed in the publication mentioned above includes an internal circumferential coil terminal
51
of a flat-face coil
50
that is spirally wound provided on the flat-face coil
50
, as shown in a sectional view presented in FIG.
8
A. Reference numeral
52
indicates an external circumferential coil terminal of the flat-face coil
50
.
The coil structure disclosed in the publication having the internal circumferential coil terminal
51
placed on the flat-face coil
50
has a large height h
1
, resulting in a poor space factor. This problem becomes even more pronounced if flat-face coils
50
are laminated as shown in
FIG. 8B
in a transformer with a large turn ratio, since the thickness h
2
increases. In addition, the problem worsens in a transformer with a large power capacity constituted by using a thick wiring material.
The insulating case in the coil apparatus disclosed in the publication if adopts a double cylinder structure having one side along the axial direction left open with notches for leading out the coil terminals provided at two positions facing opposite each other at the outer cylinder. The high-voltage side coil, the low-voltage side coil and an insulating spacer are housed inside the insulating case. The main magnetic legs of the split cores are inserted at the inner cylinder of the insulating case, and the side magnetic legs are provided outside the outer cylinder of the insulating case. The bridging portion between the main magnetic legs and the side magnetic legs of one of the split cores is set facing opposite the high-voltage side coil via the insulating spacer in this structure.
In the coil apparatus in the prior art described above in which the low-voltage side coil and the high-voltage side coil are set facing opposite each other via the insulating spacer and the coil terminals and the core, too, are set facing opposite each other via the insulating spacer, the distance which only corresponds to the thickness of the insulating spacer can be assured for the insulating distance between the high-voltage side coil and the low-voltage side coil and as the insulating distance between the high-voltage side coil and the core. For this reason, the coil apparatus cannot be utilized in a transformer that requires a larger insulating distance between the high-voltage side coil and the low-voltage side coil or between the high-voltage side coil and the core for safety reasons or due to characteristics-related requirements.
Japanese Unexamined Patent Publication No. 335158/1993 discloses other examples of a coil and a transformer constituted by using a metal plate. The coil and the transformer adopt a structure achieved by preparing coils assuming various coil terminal shapes, sequentially connecting the coils via spacers so as to allow the connecting portions where the coils are connected turn around along the direction of the circumferences of the coils and laminating them via insulating sheets.
This coil apparatus in the prior art poses problems in that the number of parts is bound to be large since coils in various shapes are utilized and in that a larger space is required for the connections.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a coil apparatus that makes it possible to insulate a one-turn coil from an adjacent member while utilizing a smaller number of members by addressing the problems of the prior art discussed above.
It is a further object of the present invention to provide a power transformer provided with a spirally-wound coil that achieves a structure with a small height by improving the space factor of the coil.
It is a still further object of the present invention to provide a power transformer in which a sufficiently large insulating distance is assured between the high-voltage side coil and the low-voltage side coil and between the high-voltage side coil and the core.
The coil apparatus according to the present invention comprises a coil, an insulating case and a core. In the coil apparatus according to the present invention, the coil includes at least a one-turn coil constituted of a metal plate, the outer periphery is formed in a ring shape having a pair of coil terminals provided at one end thereof and a projecting retaining piece provided at another end thereof. The insulating case includes a plate member having a magnetic leg insertion hole at which main magnetic legs of the core is inserted, with a fitting wall at which the coil is fitted provided around a coil mounting surface at the plate member, notched portions provided at a coil terminal mounting side and the opposite side from the coil terminal mounting side at the fitting wall of the insulating case, a first retaining portion and a second retaining portion for retaining the coil provided at extended portions extending along the radial direction at the notched portions, the coil fitted in at the fitting wall and the coil terminal and the retaining piece of the coil respectively retained at the first retaining portion and the second retaining portion to prevent the coil from lifting off the insulating case. The core is constituted of split cores each having main magnetic legs, side magnetic legs and a bridging portion between the main magnetic legs and the side magnetic legs, with the main magnetic legs of the core inserted at the coil, the side magnetic legs set toward the external circumference of the insulating case and one bridging portion set facing opposite the coil over a distance.
In this structure, the 1-term coil constituted of a metal plate which is housed inside the insulating case is insulated on one side from other members that are adjacent to it such as the core, a coil and the like by the plate member of the insulating case. A sufficient gap is formed between the coil and another member, which may the core on the opposite side with the front end of the fitting wall of the insulating case coming in contact with the other member such as the core and insulation is achieved by the gap. As a result, the coil apparatus can be achieved without having to utilize an insulating sheet, i.e., with a smaller number of parts.
In addition, the coil apparatus according to the present invention assumes a structure in which the retaining piece at the coil is retained at the second retaining portion of the insulating case with a sufficient retaining margin to allow it to move along the rotational direction relative to the second retaining portion and the first retaining portion of the insulating case is used to retain at least either of the pair of coil terminals as the coil is turned.
In a structure which allows a coil terminal to be retained by rotating the coil as described above, the coil can be connected and retained at the insulating case through a simple process.
In addition, the coil apparatus according to the present invention may further comprise a bobbin and another coil wound around the bobbin. The bobbin includes a cylindrical winding drum and flanges formed at the two en
Hashimoto Akihiro
Kyoso Yasuo
Misono Torao
Donovan Lincoln
Nguyen Tuyen T.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
LandOfFree
Coil apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coil apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coil apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3169028