United States Patent [19.]
DAlessio [111 7 3,831,124 [451 Aug. 20, 1974 MAGNETIC CORE APPARATUS [75] Inventor: Alfonso Joseph DAlessio,
Rockaway, NJ.
[73] Assignee: Bell Telephone Laboratories Incorporated, Murray Hill, NJ.
22 Filed: Nov. 8, 1973 211 App]. No.: 413,878
[52] US. Cl. 335/298, 336/176 [51] Int. Cl. H01f 3/00 [58] Field of Search 335/296, 298; 336/175, 336/ 176 [56] References Cited UNITED STATES PATENTS 2,291,013 7/1942 Wheeler 336/176 X 7/1949 Smith 336/176
X 4/1973 Schweitzer 336/176 X Primary Examiner-George Harris Attorney, Agent, or Firm-A. D. Hooper ABSTRACT A magnetic core apparatus includes two arcs of magnetic material which are rotatably mounted with respect to each other within a holder. The arcs can be rotated into alignment for placement about conductors not having accessible ends and then locked thereabout by rotating the arcs out of alignment.
7 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to magnetic core apparatus and more particularly to a magnetic core adapted for installation about conductors having no accessible end.
2. Description of the Prior Art There are many applications where magnetic cores must be installed around conductors and the like which have no readily accessible end over which the magnetic core can be slipped. In such applications the conductors must either be disconnected to provide an accessible end or the magnetic core must be segmented to allow its installation about the conductors. A common practice has been to segment the core into two 180 degree parts or arcs which are then installed about the conductors in an abutting end-to-end configuration by a suitable bracket'or other mounting means. Such an arrangement has disadvantages including the relatively long time required for installation of the mounting brackets because of the numerous parts involved and the relatively poor magnetic coupling between the abutting ends of the two segments.
Accordingly, it is an object of this invention to provide a magnetic core apparatus which can be quickly installed about conductors having no accessible end.
Another object is to simplify magnetic core apparatus for installation about conductors having no accessible end.
SUMMARY OF THE INVENTION The foregoing objects and others are achieved in accordance with this invention by a magnetic core which includes two circular arcs of magnetic material. Each arc has a groove in a face thereof anda rail such as an arc of low friction material is mounted in the groove so that the arcs mate together but can rotate with respect to each other on the rail. An arc snap ring snaps around the assembled magnetic arcs. The ring includes two upstanding flanges which hold one are and the rail stationary with respect thereto but allows the other are to rotate with respect thereto. The rotatable arc is rotated into alignment with the stationary arc to form a gap and permit installation of the core about a cable. Then the rotatable arc is rotated in the ring as much as 180 with respect to the stationary arc to close the gap thereby locking the core about the cable and providing a substantially continuous circular magneticpath about the cable.
BRIEF DESCRIPTION OF THE DRAWING The invention will be more fully comprehended from the following detailed description and accompanying drawing in which:
FIG. 1 is a perspective view of two magnetic arcs mounted in alignment with each other;
FIG. 2 is a perspective view of a snap ring or holder for mounting about the arcs of FIG. 1;
FIG. 3 is a perspective view of the ring of FIG. 2 installed about the arcs of FIG. 1 whichremain in an aligned configuration;
v 2
FIG. 4 is a perspective view similar to FIG. 3 with the are slightly rotated with respect to each other; and
FIG. 5 is a perspective view similar to FIGS. 3 and 4 with the arcs rotated approximately with respect to each other.
DETAILED DESCRIPIION' FIG. 1 shows two
arcs 2 and 4 of a magnetic material aligned with each other so as to produce a
gap 6 between the ends thereof through which a continuous conductor or the like can be inserted into the interior or center cavity 8 of the
arcs 2 and 4.
Arcs 2 and 4 have angular dimensions greater than 180. Advantageously the dimensions of
arcs 2 and 4 can be in the neighborhood of 300 so that
gap 6 has an angular dimension of approximately 60 when
arcs 2 and 4 are aligned as shown. The desired dimension of
gap 6 will of course depend upon the size of the cable or other object about which
arcs 2 and 4 are to be placed. The angular dimensions of
arcs 2 and 4 are made as large as possible consistent with this desired dimension of
gap 6.
Arcs 2 and 4 can be made identical to each other if desired to obtain manufacturing economies.
The mating faces 10 and 12 of
arcs 2 and 4, respectively, are smooth and planar to allow close mating for good magnetic coupling therebetween. Each
face 10 and 12 has an
arcuate groove 14 and 16, respectively, therein extending the full angular extent of the face. Mounted within
grooves 14 and 16 is a rail or
arcuate member 18 which has an angular dimension equal to that of
arcs 2 and 4. Rail l8 advantageously comprises an arc of low friction material such as the synthetic resin polymer commercially available under the trademark TEFLON which allows
arcs 2 and 4 to readily rotate with respect to each other along
rail 18. The
outer face 22 of
arc 4, and also the
outer face 20 of are 2 if the arcs are identical includes small depressions or dimples 24 therein for purposes to be subsequently explained. The
inner surfaces 44 and 46 of
arcs 2 and 4, respectively, include grooves or
recesses 45 and 47 spaced approximately 180 apart thereabout for uses to become clearer subsequently.
FIG. 2 shows a holder or
snap ring 30 which is adapted to hold
arcs 2 and 4 in mating relationship on
rail 18.
Ring 30 includes an arcuate flange or
wall 32 having upstanding ribs or
fingers 34 along both edges thereof.
Wall 32 advantageously has an angular dimension substantially equal to that of
arcs 2 and 4.
Wall 32 includes two
upstanding tabs 36 on the
ends 38 thereof which extend slightly less than half way across the
width 40 of
wall 32 to prevent are 4 from rotating with respect to
holder 30. Two of the
upstanding fingers 35 along one edge of
wall 32 include beads or
protrusions 42 formed thereon and adapted to mate with
dimples 24 on are 4 to provide a further locking or detenting action therewith. The
outside surface 48 of
ring 30 includes two hubs or
ridges 49 which are adapted to fit within
grooves 45 and 47 when these grooves are aligned to provide a locking or detenting action for locking
arcs 2 and 4 in position'with respect to each other. I-Iubs 49 are located approximately 180 degrees apart on
surface 48.
Ring 30 advantageously can be formed from a spring metal.
Ring 30 is placed within center cavity 8 so that the
inner surfaces 44 and 46 of
arcs 2 and 4, respectively, lie along the
outside surface 48 of
wall 32 with
fingers 34 upstanding along
outer faces 20 and 22 to hold
arcs 2 and 4 in mating relationship on
rail 18 as is shown in FIG. 3.
Tabs 36 contact the
end faces 52 of are 4 and a portion of
rail 18 and
beads 42 mate with
dimples 24 to hold or lock
arc 4 and rail 18 stationary with respect to
ring 30.
Tabs 36 do not contact the
end faces 50 of are 2. Thus
arc 2 can rotate with respect to
ring 30,
arc 4 and
rail 18 along the
rail 18 while faces 10 and 12 remain in close mating contact. When
arcs 2 and 4 are aligned with each other, i.e., when the end faces 50 and 52 lie in substantially the same plane,
hubs 49 also mate with
grooves 45 and 47 to provide a detenting or locking action to hold
arcs 2 and 4 aligned. Thus the arcs can be placed about a continuous cable or the like by passing the cable through slot or
gap 6.
After
arcs 2 and 4 are placed about the cable,
gap 6 is closed by applying a moment to are 2. When sufficient moment is applied, the detent force between
hubs 49 and
grooves 45 in
arc 2 is overcome allowing
arc 2 to rotate on
rail 18 with respect to are 4 as shown in H0. 4. Arc 2 advantageously is rotated 180 at which time grooves 45 and 47 are again aligned and
hub 49 again engages these grooves to lock the arcs about the cable with
gap 6 closed and with a substantial area of contact between
arcs 2 and 4 to provide good magnetic coupling therebetween as shown in FIG. 5.
The magnetic core apparatus of this invention can quickly and easily installed or removed from cables by a twisting motion which moves
arcs 2 and 4 into and out of alignment as required. This offers significant economies over existing split core apparatus.
The close mating of
arcs 2 and 4 along
faces 10 and 12 and the substantial angular dimension of these arcs provides very good magnetic coupling between the arcs so that the arcs present a substantially continuous circular magnetic path about an enlcosed cable. This is a significant advantage over split core apparatus which present magnetic path discontinuities at abutting ends of arcs of relatively small angular dimensions.
While the invention has been described with reference to a specific embodiment thereof, it is to be understood that various modifications thereto might be made without departing from the spirit and scope of the following claims.
What is claimed is:
1. Magnetic core apparatus adapted for installation about conductors having no accessible end, comprising, in combination:
first and second arcs of magnetic material each having an angular dimension of greater than 180 each of said arcs including a substantiallyplanarface having an arcuate groove therein; an arcuate rail installed in said grooves for rotatably mounting said arcs with respect to each other with said planar faces in opposing mating relationship; and I a holder mounted about said arcs for holding said arcs in said mating relationship and including two upstanding flanges thereon which hold said first arc and said rail stationary with respect to said holder while permitting said second arc to rotate with respect to said holder, whereby said second arc can be rotated into alignment with said first arc to produce a gap by which said apparatus can be installed about said conductors, and said gap can be closed by further rotation of said second arc.
2. Apparatus in accordance with claim 1 wherein said angular dimension of said arcs is substantially 300.
3. Apparatus in accordance with claim 1 wherein said arcs include interior surfaces contacting said holder and having depressions formed therein, and said holder includes protrusions thereon adapted to mate with said depressions and hold said arcs in preselected positions with respect to each other.
4. Apparatus in accordance with claim 3 wherein said depressions and said protrusions are spaced 180 apart on said'arcs and said holder, respectively, so that said arcs can be held in first and second positions wherein said gap is fully open and fully closed, respectively.
5. Apparatus in accordance with claim 1 wherein said rail comprises an arc of low friction material to facilitate rotation of said arcs with respect to each other.
6. Apparatus in accordance with claim 1 wherein said holder comprises an arcuate wall having an angular dimension substantially the same as said angular dimension of said arcs, and upstanding fingers along the edges of said wall for receiving said arcs therebetween to hold with respect to said holders.