Electromagnetic induction apparatus with tap winding conductors

An electromagnetic induction apparatus having an even number of coaxially disposed flat coils each having a main winding conductor and tap winding conductors wound in parallel along at least a portion of the main winding conductor to form together a flat coil. The main winding conductors are connected together by connecting the inner end of the main winding conductor of each odd-numbered one of the even number of flat coils to the inner end of the main winding conductor of the adjacent even-numbered flat coil, and connecting the outer end of the main winding conductor of the even-numbered flat coil to the outer end of the main winding conductor of the succeeding odd-numbered flat coil. The tap winding conductors are connected together by connecting the inner end of each of the tap winding conductors of each odd-numbered one of the even number of flat coils to the inner end of the corresponding tap winding conductor of the adjacent even-numbered flat coil, and connecting the outer end of each of the tap winding conductors of the even-numbered flat coil to the outer end of the corresponding tap winding conductor of the succeeding even-numbered flat coil. Upright lead portions are formed on each of the outer ends of both the main winding conductors and the tap winding conductors of flat coils which are located at opposite ends of the even number of flat coils.

BACKGROUND OF THE INVENTION 
The present invention relates to a winding structure which is applicable to 
an electromagnetic induction apparatus. 
FIG. 1 is a diagrammatic perspective view of a typical example of the prior 
art winding structure of such an electromagnetic apparatus. As shown, a 
pair of flat coils 1 and 2 (hereinafter referred to simply as "coils") are 
wound substantially coaxially with respect to each other. The coils 1 and 
2 include winding conductors whose inner ends are connected to each other 
at a connection P to connect the coils 1 and 2 in series. These coils 1 
and 2 further include a plurality of tap leads 3 each of which have one 
end connected to an intermediate portion of the winding conductor and 
which extend in a direction intersecting the outer peripheries of the 
corresponding coils 1 and 2. The outer portions of the coils 1 and 2 
including the tap leads 3 are hereinafter referred to as "tap winding 
portions" (the non-hatched portions in the figure) while the inner 
portions of the coils 1 and 2 including no tape leads 3 are hereinafter 
referred to as "main winding portions" (the hatched portions in the 
figure). The tap winding portions of the coils 1 and 2 are provided with 
transposition points Q in order to cancel the circulating currents 
generated in the tap winding portions. 
Referring to FIG. 2, which is a circuit diagram of the winding structure 
shown in FIG. 1, the series-connected coils 1 and 2 each include a 
plurality of tap leads 3 (in this example, three tap leads for each coil). 
FIG. 3 is a diagrammatic side view taken in the direction of an arrow A of 
FIG. 1. A distance d.sub.1 represents the insulation distance between the 
tap leads 3 of the coil 1 and the tap leads 3 of the coil 2. A distance 
d.sub.2 represents the insulation distance between the coil 1 and the tap 
leads 3 attached thereto and between the coil 2 tap leads 3 attached 
thereto. A distance d.sub.3 represents the insulation distance between the 
coils 1 and 2. 
FIGS. 4 and 5 illustrate typical examples of the shape of the winding 
conductor at the transposition points Q of the coils 1 and 2. FIG. 4 shows 
one example which has no joint area while FIG. 5 shows another example 
which has a joint. 
The tap leads 3 are connected to the winding conductor of the corresponding 
coil 1 or 2, as shown in FIG. 6. 
In the prior art electromagnetic induction apparatus as arranged above, the 
tap leads 3 are connected directly to the winding conductors of the coil 
so as to form tap portions. Also, in order to cancel the circulating 
currents generated in the tap winding portion, at the transposition points 
Q of the coils 1 and 2, the corresponding winding conductors must be 
transposed by being twisted 180.degree. about their center lines (shown by 
the dot-dash line in FIG. 4). 
It is to be noted that, although in the example of FIG. 4 there is no joint 
area, the winding conductors may also have a joint connecting them to each 
other as shown in FIG. 5. 
The prior art electromagnetic induction apparatus having the 
above-described arrangement includes a winding structure in which the tap 
leads are connected directly to the winding conductors, as shown in FIG. 
6. For this reason, it is necessary to maintain the insulation distances 
d.sub.2 between the coil 1 and the tap leads 3 attached thereto and 
between the coil 2 and the tap leads 3 attached thereto, as shown in, for 
exmaple, FIG. 3. This prior art winding structure has a disadvantage in 
that this necessity increases the whole size of the electromagnetic 
induction apparatus. In addition, in order to connect the tap leads to the 
winding conductors, additional work is required to peel an insulating 
coating from the portions of the winding conductors to which the tap leads 
are to be connected. This presents a problem in that in assemblying the 
electromagnetic induction apparatus is reduced. In addition, as shown in 
FIGS. 4 and 5, in order to cancel the circulating currents generated in 
the tap winding portions, transpositions must be effected in the winding 
portions. This makes it more difficult to form the windings. The prior art 
electromagnetic induction apparatus involves the above-described problems. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an 
electromagnetic induction apparatus having a coil winding structure which 
can be provided with a given number of tap leads without any need to make 
the tap leads project from the side surfaces of the coil, by connecting in 
a prior art manner one end of each of the tap leads directly to the 
winding conductor of the coil. 
It is another object of the present invention to provide an electromagnetic 
induction apparatus having a winding structure which does not need the 
insulation distance (shown as the insulation distances d.sub.2 in FIG. 3) 
between each coil and the tap leads attached thereto respectively, 
reducing the insulation distance d.sub.3 between the coils. 
It is another object of the present invention to provide an electromagnetic 
induction apparatus having a winding structure provided with a winding 
portion without any transpositions which function to cancel the 
circulating currents generated in tap winding portion thereof. 
The above and other objects are achieved by the present invention which 
provides an electromagnetic induction apparatus having an even number of 
flat coils each having a main winding conductor and tap winding conductors 
which are the same in number as the taps and which are wound in parallel 
along at least a portion of the main winding conductor to form, together 
with said main winding conductor, a flat coil, the flat coils being wound 
substantially coaxially; means for connecting the main winding conductors 
together by connecting the inner end of the main winding conductor of each 
odd-numbered one of the even number of flat coils to the inner end of the 
main winding conductor of the adjacent even-numbered flat coil, and 
connecting the outer end of the main winding conductor of the 
even-numbered flat coil to the outer end of the main winding conductor of 
the succeeding odd-numbered flat coil; means for connecting the tap 
winding conductors together by connecting the inner end of each of the tap 
winding conductors of each odd-numbered one of the even number of flat 
coils to the inner end of the corresponding tap winding conductor of the 
adjacent even-numbered flat coil, and connecting the outer end of each of 
the tap winding conductors of the even-numbered flat coil to the outer end 
of the corresponding tap winding conductor of the succeeding even-numbered 
flat coil; and upright lead portions formed on each of the outer ends of 
both the main winding conductors and the tap winding conductors of flat 
coils which are located at opposite ends of the even number of flat coils. 
The electromagnetic induction apparatus of the present invention includes 
an improved coil structure, that is, a coil structure in which an even 
number of flat coils are connected in series and in side-by-side 
relationship, a desired number of taps are formed by winding the tap 
winding conductors parallel to one another around a portion or the whole 
of the main winding conductor. This structure eliminates the need to make 
the tap leads project from the side surfaces of the coil by directly 
connecting one end of each of the tap leads to the winding conductors. 
Further objects, features and advantages of the present invention will 
become apparent from the following description of a preferred embodiment 
of the present invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
A preferred embodiment of the present invention will be described below 
with reference to the accompanying drawings. 
FIG. 7 is a diagrammatic perspective view of the winding structure of an 
electromagnetic induction apparatus constituting the preferred embodiment 
of the present invention. As shown, each of flat coils 4 and 5 
(hereinafter referred to simply as "coils") includes a main winding 
conductor 6 (the hatched portion) and a plurality of (in this embodiment, 
three) tap winding conductors 7 (the non-hatched portion) which are wound 
parallel to one another around a portion of the main winding conductor 6. 
As shown in FIG. 8, the inner ends of the main winding conductors 6 of the 
coils 4 and 5 are connected to each other, and further the inner ends of 
the tap winding conductors 7 of the coil 4 are connected to the 
corresponding inner ends of the tap winding conductors 7 of the coil 
respectively. More specifically, the inner ends of the main winding 
conductors 6 of the coils 4 and 5 are connected to each other at a 
connection P which serves as means for connecting the main winding 
conductors. The inner ends of the tap winding conductors 7 of the coils 4 
are connected to those of the coils 5 at corresponding transposition 
points Q which serve as means for connecting the tap winding conductors. 
The transposition points Q are shaped as shown in FIG. 4 or 5 illustrating 
the prior art, in order to cancel the circulating currents produced in the 
tap winding conductors 7. The portions of each of the coils 4 and 5 which 
are wound into a coiled form are hereinafter referred to as the "winding 
portions 8" while the respective upright portions of the main winding 
conductor 6 and the tap winding conductors 7 are hereinafter referred to 
collectively as "upright lead portions 9". 
FIG. 8 is a circuit diagram of the embodiment shown in FIG. 7, in which 
reference characters 4 to 7, P and Q represent the same components as 
those shown in FIG. 7. The coils 4 and 5 each include the main winding 
conductor 6 shown as solid lines and the tap winding conductors 7 shown as 
broken lines, these tap winding conductors 7 being wound parallel to one 
another around a portion of the main winding conductor 6. The inner end of 
the main winding conductor 6 of the coil 4 is connected to that of the 
inner end of the main winding conductor 6 of the coil 5 while the inner 
ends of the tap winding conductors 7 of the coil 4 are connected to the 
corresponding inner ends of the tap winding conductors 7 of the coil 5 
respectively. 
FIG. 9 is a diagrammatic side view taken in the direction of an arrow A of 
FIG. 7, in which reference characters 4, 5, P and Q represent the same 
constituent elements as those shown in FIG. 7. A distance d.sub.3 
represents the insulation distance between the coils 4 and 5. 
FIG. 10 is a development view of FIGS. 7 and 9, illustrating the coils 4 
and 5 developed along the center line shown by the dot-dash line in FIG. 
9. Reference characters 4 to 7, P and Q in FIG. 10 represent the same 
components as those shown in FIGS. 7 and 9, and, in the same manner as 
FIG. 7, the hatched portions of the coils 4 and 5 represent the main 
winding conductors 6 while the non-hatched portions of the coils 4 and 5 
represent the tap winding conductors 7. 
In the electromagnetic induction apparatus having the above-described 
arrangement, the tap winding conductors 7 are wound in parallel around at 
least a portion of each of the main winding conductors 6, and the upright 
lead portions 9 of the tap winding conductors 7 are employed as tap leads. 
This arrangement eliminates the necessity for other tap leads to be 
connected directly to the winding conductors of the coils 4 and 5 in the 
manner described previously in the prior art with reference to FIG. 6. 
Accordingly, the insulation distances d.sub.2 shown in FIG. 3 are not 
needed, thereby enabling a reduction in the insulation distance d.sub.3 
between the coils 4 and 5, as shown in FIG. 9. Also, the transposition 
required for canceling the circulating currents produced in the tap 
winding conductors 7 can be effected at connecting portions between the 
coils 4 and 5 which are illustrated as the transposition points Q in FIGS. 
7 to 10. In use, terminals 6a, 6b of the main winding conductors 6 and 
terminals 7a to 7f of the tap winding conductors 7 of the coils 4 and 5 
can be connected to each other as required to provide a winding having a 
desired length. As shown in FIG. 8, for example, if, in the coil 5, the 
terminal 6b of the main winding conductor 6 is connected to the terminal 
7d of the tap winding conductor 7 while, in the coil 4, the terminals 7c 
and 7b of the tap winding conductors 7 are connected to each other, the 
winding described below can be obtained. More specifically, the terminal 
6a of the main winding conductor 6 of the coil 4 is connected via the 
connection P to the terminal 6b of the main winding conductor 6 of the 
coil 5 and, in addition, the terminal 6b is connected to the terminal 7d 
of the tap winding conductor 7. The terminal 6b is connected via the 
terminal 7d and the transposition point Q to the terminal 7c of the tap 
winding conductors 7 of the coil 4, and the terminal 7c is further 
connected to the terminal 7b. The terminal 7c is connected through the 
terminal 7b and the transposition point Q (the corresponding intermediate 
broken line is omitted) to the terminal 7e of the tap winding conductor 7 
of the coil 5. 
In the above-described embodiment, by way of example, the two coils are 
constituted by a combination of a main winding conductor and tap winding 
conductors, and, in both coils, the tap winding conductors are wound 
parallel to one another around a portion of the corresponding main winding 
conductor. Such an arrangement is not exclusive, and therefore the 
invention is not confined to the illustrative arrangement of the 
embodiment. For example, any even number of flat coils may be employed. In 
such a case, the inner ends of the main winding conductor and the tap 
winding conductors which constitute in combination an odd-numbered flat 
coil are connected to the corresponding inner ends of the main winding 
conductor and the tap winding conductors which constitute in combination 
an adjacent even-numbered flat coil. In addition, the outer ends of the 
main winding conductor and the tap winding conductors which constitute in 
combination the above even-numbered flat coil are connected to the 
corresponding outer ends of the main winding conductor and the tap winding 
conductors which constitute in combination a succeeding adjacent 
odd-numbered flat coil. With this arrangement, it is possible to construct 
any desired even number of flat coils. 
Also, in the above-described embodiment, three tap leads are provided for 
each coil by way of example. It is of course possible to form any given 
number of tap leads. 
In the above-described embodiment, the three tap winding conductors are 
wound parallel to one another around the same portion of the main winding 
conductor, that is, each of the tap winding conductors forms the same 
number of turns as shown in FIG. 8. However, such an arrangement is only 
illustrative, and it is of course possible to change the number of turns 
of each of the tap winding conductors. 
Although the upper portions of the flat coils are connected to each other 
in the above-described embodiment, the present invention is not limited 
solely to that arrangement. For example, the lower portions of the flat 
coils may be connected to each other instead. Alternatively, the 
connection may be formed at position intermediate opposing 
vertically-extending portions of the winding conductors of the coils. 
As described above, in accordance with the present invention, the tap 
winding conductors are wound in parallel around at least a portion of each 
of the main winding conductors, and upright lead portions of the tap 
winding conductors are employed as tap leads. This arrangement eliminates 
the necessity for other tap leads to be connected directly to the winding 
conductors of the coils, thereby improving efficiency of assemblying the 
electromagnetic induction apparatus and reducing the distance between each 
coil. In addition, transposition is effected at the connections between 
the coils instead of in the winding portions of the coils. This further 
facilitates the formation of the coils.