AIR CHOKE COIL WITH CONDUCTOR CROSS-OVER STRUCTURE

BOBINAGE A AIR CONDUCTEURS CROISES

English Abstract

ABSTRACT OF THE DISCLOSURE
An air-choke coil having at least two concentric wind-
ings, or winding parts, in which the windings, or winding parts,
are crossed over. Known similar coils are usually provided with
a plurality of parallel, current-carrying wires forming the
conductor. The use of a plurality of conductors substantially
reduces unwanted losses and heating produced by eddy currents
and the like. In such air-choke coils uniform distribution of
the current to a plurality of parallel conductors is usually
achieved by means of the so-called cross-over technique. The
air-choke coil according to the present invention is sub-
stantially simpler in construction in that the windings, or
winding parts, need not be wound simultaneously, as in the
case of known similar constructions. The coil comprises at
least two concentric windings, or winding parts, in which the
windings, or winding parts, are crossed. A separate crossing
piece is provided for the purpose of crossing the conductor
cables. In one embodiment the crossing piece is in the form
of a flat web with a connecting piece at each end for connect-
ing conductor cables thereto.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. An air-choke coil having at least two concentric windings
or winding parts and in which the said windings or winding
parts are crossed characterized in that a separate crossing
piece is provided for the purpose of crossing the conductor
cables.
2. An air-choke coil according to claim 1 wherein the
crossing piece is in the form of a flat web with a connecting
piece at each end for connecting conductor cables thereto.
3. An air-choke coil according to claim 2, wherein the
connecting pieces are shaped in cubic form each connecting piece
having an opening for accommodating an end of a respective conductor
cable.
4. An air-choke coil according to claims 2 or 3, wherein
the cross-section of the web is at least equal to that of the
conductor cable.
5. An air-choke coil according to claims 1, 2 or 3, wherein
the crossing piece is made of the same material as the conductor
cable.
6. An air-choke coil according to claim 3, wherein the ends
of the conductor cables are welded to the crossing piece.
7. An air-choke coil according to claims 1, 2 or 3, wherein
an insulating interlayer is inserted between the crossed conductor
and the crossing piece.
8. An air-choke coil according to claims 1, 2 or 3 wherein
spacer strips are provided in order to keep the coils apart.

9. An air-choke coil according to claims 1, 2 or 3, wherein
the coil is glued with epoxy resin for impregnating or gluing
purposes.

Description

"" 1075783
The invention relates to an air-choke coil having at
least two concentric windings, or winding parts, in which the
windings, or winding parts, are crossed over.
Known air-choke coils are usually provided, not with
one, but with a plurality of parallel, current-carrying wires
forming the conductor. This use of a plurality of conductor~
reduces to a minimum unwanted losses and heating produced by
eddy currents and the like. Furthermore, the very large conductor
diameters required by single-wire conductors are unacceptable from
a mechanical point of view.
In the case of air-choke coils having at least two
concentric windings, or winding parts, with the same number of
turns, the alternating-current impedance of the one conductor is
considerably lower than that of the other conductor. The result
of this is that most of the current flows through the conductor
having the lower impedance, thus causing excessive heating and
possible overloading.
In the case of air-choke coils, uniform distribution of
the current to a plurality of parallel conductors is usually
achieved by means of the so-called cross-over technique, already
described in United States Patent No. 1,554,250, Woodrow, issued
September 22, 1925.
In coils having large conductor cross-sections, the
crossing of the conductors takes up a considerable amount of
space, and the conductors also have to be off-set or otherwise
deformed. This i8 a disadvantage, since the production of such
conductors is time-consuming and, where large currents are
involved, the extensive assembly required also ta~es up a con-
siderable amount of space. Another problem in producing chokes
with cro~9ed conductors is that all of the conductors must be
wound simultaneously, and crossed, about a common axis.
It is the purpose of the invention to provide an air-
-~ choke coil of the type mentioned at the beginning hereof which
~ .
~ .

1075783
lacks the disadvantages of known designs and in which the
crossing of the conductor cables is substantially simplified.
In accordance with a specific embodiment of the
invention there is provided an air-choke coil having at least
two concentric windings or winding parts and in which the said
windings or winding parts are crossedj characterized in that a
separate crossing piece is provided for the purpose of crossing
the conductor cablesO
m e main advantage of the invention is to be perceived
in that in the case of air-choke coils having a plurality of
concentric windings or winding parts the winding operation is
substantially simpler and the windings, or winding parts need
no longer be wound simultaneously.
The crossing piece is preferably in the form of a flat
web with a connectlng piece for the conductor cables at each end.
As a result of this only a smal-l amount of space is needed for
the crossing piece between the conductor cables. Cubic form
connecting pieces having an opening accommodating the end of one
conductor cable are particularly suitable as connecting pieces.
The cross-section of the web is preferably at least as large as
that of the conductor cable, so that the ohmic resistance of the
crossing piece is no higher than that of an equal length of the
conductor cable. m e crossing piece is preferably made of the
same material as the conductor cable. In order to avoid contact
resistances between the conductor cables and the crossing pieces
- it is desirable to weld the ends of the conductors to the connect- - -
ing pieces of the crossing piece. m is makes it possible to wind
... . .
the coil under tension without any danger of the conductor cable
being pulled out of the crossing pieceO For reasons of safety
an insulating interlayer is inserted between the cross conductors
and the crossing piece. Spacer strips are preferably used to
space the coils. Impregnating or gluing is preferably carried out
- ~ by immersing the coil in an epoxy resin which hardens later.
. . - - . - , . . . ~
.' . ; ' ' , ~ . ' :. . ' ~

~07S7~3~
In a drawing of one embodiment of the present invention:
Fig. 1 is a side elevation of two conductor cables
in an air-choke coil crossed over by means
of a crossing piece, and
Fig. 2 is a bottom plan view of the arrangement accord-
ing to Fig. 1.
In Fig. 1, a crossing piece 2, made of an electrically-
conducting material, is located above a conductor cable 1. The
crossing piece consists of a flat web 3 having a connecting piece
4, 4* in the form of a cube situated at each end thereof. Each
of the connecting pieces is provided with a bore to accommodate
the ends of a second conductor cable 5, 5*.
As may be gathered from Fig. 2, conductor cable 1 is
bent slightly in the shape of an S and crossing piece 2 is
located directly above this S-bend. Running parallel with
conductor cable 1 is a second conductor cable 5, 5* which is
cut at the location of the S-bend in conductor cable 1. Ends
6, 6* of conductor cable 5, -5* are inserted into the bores of
cube-shaped connecting pieces 4, 4*, to which they are welded.
A spacer strip 7 is arranged between conductor cables 1 and 5.
The air-choke coil is preferably produced as follows:
the conductor for the first coil, beginning in the inside, is
wound as far as the first cross-over location, the crossing
piece is secured to the conductor cable, spacing means are
fitted to the outside of the coil part; the next coil is then
wound thereover as far as the cross-over location and is wound
further with the radius of the preceding coil as far as the next
cross-over location, a crossing piece is secured to the conductor
cable of the second coil, spacing means are again fitted, and the ~-
; 30 procedure applied to the second coil is repeated for each sub-
sequent coil, but the last coil is not fitted with a crossing
piece, a conductor cable is secured to the crossing piece of the
first coil, and winding proceeds under tension, to the end of the
- 3 -

10757~;~
coil. This sequence of operations is repeated for the remainingcoils, and the whole air-choke coil is finally impregnated or
glued.
The air-choke coil according to the invention not only
has the advantage of eliminating the complex winding operation
associated with air-choke coils having a plurality of concentric
windings, or winding parts, and also the simultaneous winding of
a plurality of coils, but also makes it possible to carry out the
cross-overs without losing valuable winding space. Furthermore,
off-sets and other deformations are no longer necessary. By
means of the crossing piece described above, air-choke coils may
be produced with any desired number of concentric windings.
4 -