US3784946A

US3784946A - Smoothing choke

Info

Publication number: US3784946A
Application number: US00335930A
Authority: US
Inventors: Jacques Van Hulse; Roald Bingen
Original assignee: ACEC
Current assignee: ACEC CATELIERS DE CONSTRUCTIONS ELECTRIQUES DE CHARIEROL BE; ACEC
Priority date: 1972-02-25
Filing date: 1973-02-26
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: DE2308795B2; FR2173171A1; NL178204C; FR2173171B1; CA1002622A; NL178204B; IT977489B; BE779905A; BE780293A; DE2308795C3; NL7302538A; SE385518B; DE2308795A1

Abstract

This invention concerns a smoothing choke of a highly reduced weight. The smoothing choke consists of a magnetic core made up of a stock of trapezoidal metal sheets having the two parallel sides thereof alternately reversed so as to obtain a core of general parallepipedal shape having, at each end thereof, a groove in the shape of a triangular prism. A coil is wound around the core and has outer turns the perimeter of which is successively reduced by step-like winding, from the turns around the central part of the core, symmetrically, to the turns around the ends of the latter.

Description

United States Patent [191 Bingen et al.

[ Jan. 8, 1974 SMOOTHING CHOKE [75] lnventors: Roald Bingen, Marcinelle; Jacques Van Hulse, De Pinte, both of Belgium [73] Assignee: ACEC Cateliers DE Constructions Electriques de Charierol, Cl arleroi, Belgium 22 Filed: Feb. 26, 1973 211 Appl. No.: 335,930

[30] Foreign Application Priority Data Feb. 25, 1972 Belgium P 3822 Mar. 7, 1972 Belgium .l P 3823 [52] US. Cl 336/59, 336/225, 336/231, 336/234 [5 l] Int. Cl. H0lf 27/02 [58] Field of Search 336/60, 84, 233, 336/234, 225, 231, 221,59

[56] References Cited UNITED STATES PATENTS 1,260,743 3/l9l8 Attila 336/234 X I I v McCord 336/234 X Reade 336/234 X FOREIGN PATENTS OR APPLICATIONS 254,616 1/1963 Australia 336/225 Primary Examiner-Thomas J. Kozma Att0rneyRaymond A. Robic [57] ABSTRACT This invention concerns a smoothing choke of a highly reduced weight. The smoothing choke consists of a magnetic core made up of a stock of trapezoidal metal sheets having the two parallel sides thereof alternately reversed so as to obtain a core of general parallepipedal shape having, at each end thereof, a groove in the shape of a triangular prism. A coil is wound around the core and has outer turns the perimeter of which is successively reduced by step-like winding, from the turns around the central part of the core, symmetrically, to the turns around the ends of the latter.

10 Claims, 2 Drawing Figures PATENTEUJAN W 3.784.946

.m-H 1. [if 2 FIG.1

PATENTEDJAN 4 3,784,946

'suwauFz FIG, 2

SMOOTHING CHOKE The present invention relates to self-induction coils with open-magnetic circuit and, in particular, to smoothing chokes useful in current regulating electronic apparatus for regulating the feed-current of impulse working traction motors.

The invention concerns a smoothing choke, of highly reduced weight, which is most important for an apparatus set up in a vehicle.

According to the invention, a first means for obtaining a substantial reduction in the weight of a coil of this type consists in using a magnetic core made up of a stack of trapezoidal metallic sheets the two parallel sides of which are alternatively reversed so as to obtain a core of a generally parallelepiped form having, at each end, a groove in the shape of a triangular prism. As it has been observed, these grooves do not substantially change the induction coefficient of a coil placed around the core as compared to the coefficient that would be obtained if the core were a complete rectangular parallelepiped.

It has been noted, on the other hand, that with this type of core the lines of force of the magnetic field produced by the coil are much closer to the core at its ends than if the latter were a rectangular parallelepiped of the same external size. In accordance with the invention, advantage is taken of this characteristic by distributing the winding along the height of the core so that the perimeter of the outer turns be successively reduced from the ones around the central part of the core to the ones around the ends of the same. In this manner, the area defined by each outer turn is best adapted to the flux through it and a substantial reduction in the length of the average turn is obtained when compared with a coil containing the same number of turns of the same cross-section of which the outer turns have all the same width. As a result, a substantial reduction in the weight of copper is obtained which may be improved some more due to the fact that the coil has a greater external cooling area, which allows the use of a coil contuctor having a smaller cross-section.

The invention will now be disclosed with reference to a preferred embodiment thereof, by way of example, and to the accompanying drawings in which:

FIG. 1 is a perspective view of a core made up of a stack of metallic sheets in accordance with the invention;

FIG. 2 is an elevation view of a smoothing choke with the magnetic core of FIG. 1.

FIG. 1 show a core made up of a stack of

trapezoidal metal sheets

1 and 2, alternatively disposed, the parallel sides of which are super imposed, the larger side of one fallowing the smaller side of the other and vice versa; for the sake of clarity, these are shown separated from one to the other. The

sheets

1 and 2 are identical and made from a strip having a width 1; the end edges of which are symetrically cut out at 45 with respect to the parallel edges of the strip. In this manner, there is obtained a magnetic core of a general parallelepipedal shape from which a prismatic volume equal to l L/2 is cut off at each end, L being the thickness of the stack of sheets, so that the parallelepiped is reduced by a total volume of 1 L, which is, in general, quite an important portion.

The production cost is also proportionally reduced because of the lesser weight of sheets used and of the bevelling thereof which avoids any loss.

FIG. 2 is a cross-section view of a smoothing choke equiped with the magnetic core shown in FIG. 1. On this core, there is wound a coil 3 the turns of which are in step-like formation symmetrically on either side of a central part with respect to a median plane which is perpendicular to the core so that the outer turns progressively get shorter as they move away from the central portion.

It has been foun that such a coil has substantially the same induction coefficient as a coil having the same number of turns, such as shown in dotted lines in FIG. 2, and for which the average length of a turn would be greater, corresponding to a greater weight of copper. In as much as the coil according to the invention has a larger outer cooling ares, the cross-section of the winding conductor may be reduced, which means an additional reduction in the weight of copper used.

It can therefore be seen that the use of th disclosed magnetic core, which already has a reduced weight as compared to the parallelpiped core of the same external size, allows the use of a coil having a weight smaller than that of a known coil. Therefore, these combined features result in a smoothing choke of a total weight clearly smaller than that of known chokes of the same electrical characteristics.

The chokes shown in FIG. 2 may be secured by means of wedge-

like member

4 and 5 fitting into the prismatic grooves at the ends of the core and assembled by rods 6 secured to transverse members 7 and 8. The foregoing combination is thus quite resistant to vibrations. I

The smoothing choke described above which has a stary field of little scathering beyond the winding may be covered with a steel split housing, not shown, used as a magnetic screen and capable of acting as a ventilation flue.

We claim 1. A smoothing choke comprising a magnetic core made up of a stack of metal sheets having the two parallel sides thereof alternately reversed, said core having at each end thereof a groove in the form of a triangular prism; and

a coil wound around said magnetic core, the perimeter of the outer turns of said coils being successively reduced, whereby a substantial reduction in the weight of said smoothing choke is obtained when compared to the weight of known chokes.

2. A smoothing choke as claimed in claim 1 wherein each of said metal sheets is trapezoidal.

3. A smoothing choke as claimed in claim 2, wherein said metal sheets are set up so as to obtain a core of general parallelepipedal shape.

4. A smoothing choke as claimed in claim 1 wherein said perimeter of said outer turns is reduced by steplike winding.

5. A smoothing choke as claimed in claim 4 wherein the reduction in said perimeter is from the turns around the central part of said core to the turns around each end thereof, symetrically.

6. A smoothing choke as claimed in claim 1, wherein the outer turns of said coil progressively get shorter as said turns move away from the central portion of said core.

3 4 7. A smoothing choke as claimed in claim 1, wherein a magnetic core made up of a stack of trapezoidal said core is fixed by means of V-shape side parts fitting metal sheets having the two parallel sides thereof into the prismatic grooves at the ends of said core and alternately reversed so as to obtain a core of genmeans holding said side parts and coil together. eral parallelepipedic shape having, at each end 8. A smoothing choke as claimed in claim 1, wherein 5 thereof, a groove in the form of a triangular prism; said choke is secured by means of wedge-like member a coil wound around said core and having outer turns fitting into said prismatic grooves and assembled by the perimeter of which in successively reduced, by means secured to transverse members. step-like winding from the turns around the central 9. A smoothing choke as claimed in claim 1, wherein part of said core, symetrically, to the turns around said choke is covered with a split housing capable of 0 the ends of said core, whereby a substantial reducacting as a magnetic screen for the stray field of said tion in the weight of said choke is obtained when choke and as a ventilation flue. compared to the weight of known chokes.

10. A smoothing choke comprising:

Claims

1. A smoothing choke comprising : a magnetic core made up of a stack of metal sheets having the two parallel sides thereof alternately reversed, said core having at each end thereof a groove in the form of a triangular prism; and a coil wound around said magnetic core, the perimeter of the outer turns of said coils being successively reduced, whereby a substantial reduction in the weight of said smoothing choke is obtained when compared to the weight of known chokes.

4. A smoothing choke as claimed in claim 1 wherein said perimeter of said outer turns is reduced by step-like winding.

7. A smoothing choke as claimed in claim 1, wherein said core is fixed by means of V-shape side parts fitting into the prismatic grooves at the ends of said core and means holding said side parts and coil together.

8. A smoothing choke as claimed in claim 1, wherein said choke is secured by means of wedge-like member fitting into said prismatic grooves and assembled by means secured to traNsverse members.

9. A smoothing choke as claimed in claim 1, wherein said choke is covered with a split housing capable of acting as a magnetic screen for the stray field of said choke and as a ventilation flue.

10. A smoothing choke comprising: a magnetic core made up of a stack of trapezoidal metal sheets having the two parallel sides thereof alternately reversed so as to obtain a core of general parallelepipedic shape having, at each end thereof, a groove in the form of a triangular prism; a coil wound around said core and having outer turns the perimeter of which in successively reduced, by step-like winding from the turns around the central part of said core, symetrically, to the turns around the ends of said core, whereby a substantial reduction in the weight of said choke is obtained when compared to the weight of known chokes.