Note: Descriptions are shown in the official language in which they were submitted.
1~4854
¦¦ ~he present invention relates to a~ electromagn~t ~or
¦ an electric switching device, particularly safety switch or
circuit breaker, which includes a movahle ar~ature and a
magnetic core.
Armatures and magnetic cores of -the electromagnets of
! safety switches are formed of laminations assembled into packs
and connected to each other by rivets.
~lectromagnets of the ~oregoing type are usually
utilized in mass production for switching devices of various
types. Various switching devices require, depending on their
structure, size and output, different electromagnets. However
efforts have been made to standardize such electroma~nets.
The manufacture of electromagnets for electric
switches is usually very expensive because special cutting tools
or punching tools are required for making armatures, on the one
hand, and Magnetic cores, on the other hand. Furthermore, huge
storage spaces are required for storing tools for making
electromagnets of various sizes and constructions. Furthermore,
rivets utilized for holding laminations in a pack have been
differently positioned for the armature and the magnetic core
so that different riveting stations have been reguired for
manufacturing armatures and magnetic cores.
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12~485~
It is an object of the present invention to provide
an improved electromagnet for electric switches, particularly
safety switches.
It is another object of this invention to provide an
electromagnet which is easy to manufacture automatically and
which is inexpensive to make.
These and other objects of the invention are attained
by an electromagnet for an electromagnetic switching device,
particularly safety switch, comprising a magnetic core and a
~ovable armature, said core and said armature being each formed
of a plurality of superposed laminations assemhled into a pack
and connected to each other by rivets, said core and said
armature being each assembled of evenly-shaped laminations.
Due to the invention, instead of conventional four
cutting or punching tools and respective machines, only two
cutting or punching tools are re~uired.
If the electromagnet is utilized for alternating
current the armature and the core each may include two outer
legs and one central leg, each outer leg being formed with a
widened portion extending towards the central leg, at least
the widened portion of one outer leg having an end face formed
with grooves for receiving therein a short circuit ring.
If the electromagnet is utilized for direct current,
one of the outer legs may have at its free end an oblique
surface which merges into a flat end face, the other of the
3~L~354
outer le~s having a free end fo~led with another ohlique
sur:Eace and with a ~lat stop surface, said another obli~e
surface and the stop surface fit said first mentioned o~lique
surface and said end face, respectively when the armature i~
laid over the magnetic core, said central leg having a further
oblique surface such that an air gap results between the
further oblique surface of the central leg of the core and the
further oblique surface of the central leg of the armature when
the latter and the core are in assembly.
Each pack may be provided with holes for said rivets,
and positions of said holes and said rivets in each pack may be
selected so that these positions be the same for all armatures
and ~agnetic core of electromagnets operated with alternating
current or with direct current. A further advantage of this
invention resides in the fact that instead o~ four riveting
tools or riveting ~achines, required in conventional method of
manufacture o~ electromagnets, only a single rivetin~ tool or
riveting machine is now re~uired.
The laminations may be punched out to have a profile
so that a mechanical after treatment of said laminations would
be oMitted.
The central leg may have two trapezoidal projections
having outer inclined surfaces and an intermediate inclined
surface which form said ~urther oblique surface, the sum of the
lengths of said outer inclined surfaces heing equal to the
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length of said intermediate inclined surface.
One of said outer legs may have at said end a
trapezoidal recess defined by two symmetrically extendiny
oblique surfaces, and another of said outer legs may have at
the end thereof a trapezoidal projection which matches said
recess.
One of said outer legs may have at said recess two
end faces and another of said outer leys may have at said
projection two stop surfaces.
The novel features which are considered as charac-
teristic for the invention are set forth in particular in the
appended claims. The invention itself, however, both as to its
construction and its method of operation, together with addi-
tional objects and advantages thereof, will be best understood
from the following description of specific embodiments when read
in connection with the accompanying drawings.
1~3485~
l Fig. 1 is a front view of an alternating current
i magnetic core;
Fig. 2 is a front view of an electromagnet in which
the armature and the magnetic core have the same construction;
Fig. 3 is a side view of the electromagnet o~ F'ig. 2;
Fig. 4 is a front view of an alternating current
magnetic core of another embodiment;
Fig. 5 is a top plan view of Fig. 4;
Fig. 6 is a front view of a direct current magnetic
core;
Fig. 7 i5 a side view of Fig. 6;
Fig. 8 is a front view of an electromagnet for direct
current, in which the armature and magnetic core are similarly
formed in accordance with Fig. 6;
Fig. 9 is a front view of a drill template for the
armature and the core to be used for alternating current
magnets and direct current magnets as well;
Fig. 10 is a front view of yet another embodiment of
an alternating current magnetic core;
Fig. 11 is a front view of an electromagnet in which
the armature and the core are ali~e and ~ormed in accordance
with Fig. 10;
Fig. 12 is a side view of Fig. 10;
Fig, 13 is a front view of still further modification
of a direct current core or armature; and
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Fig. 14 is a front view of a further embodiment of
an electroma~netic for direct current.
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34~35~L
I Referring now to the drawings in detail, and first to
¦ Figs. 1-3 thereof, these figures illustrate an electromagnet for ¦
alternating current, in which a magnetic core 1 and an armature
14 are fully identical. This is clearly seen from Fig. 2. mhe
magnetic core 1 and armature 14 accordingl~ each has three legs
2, 3 and 4 extended outwardly from the base and keing parallel
to each other. The core 1 and armature 14 each is comprised of
a package of superposed laminations 15. The thickness of the
package can vary, however the same cutting tools and riveting
tools can be used to produce the core or the armature. Lamina-
tions 15 are connected to each other in a pack by means of
rivets 5, 6, 7, 8 and 9; it is therefore important that the
positions of holes for rivets and correspondingly, of rivets for
the armature and the core be selected at the same places.
Grooves 10 and 11 are punched in the leg 2. A short-circuit
ring 12 is inserted into grooves 10 and 11. Fig. 2 clearly
illustrates by the position of the short-circuit ring 12 that
magnetic core 1 and armature 14 of the same shape are pivotable
relative to each other.
A recess 13 serves, in case of the magnetic core, for
connecting the core with a housing of a switching device or any
other stationary element whereas, in case of an armature, this
recess serves for connecting to a movable member of the
switching device. As seen from Fig. 2 an air gap remain
¦ between two middle legs 3 of magnetic core 1 and armature 14.
~''.''
.
1~3A~854
~ith reference to Eigs. 4 and 5, which show a further
embodiment of the electromagnet for a circuit breaker, it will
be seen that in this embodiment the structure of the core and
the armature substantially coincides with that of Figs. 1-3,
Portions of the structural components in Figs. 4 and 5, similar
to those of Figs. 1-3, are denoted by like reference numerals.
The armature and the magnetic core each also has thr~e leys 2,
3 and 4. Outer legs 2 and 4 have each an inwardly projecting
widened portion 17, 18. Grooves 19 and 20 are forrned in a
lower end face of widened portion 18. Grooves 19 and 20
receive a non-shown short-circuit ring similar to the embodi~ent
of Figs~ 1-3. Instead of recess 13 an opening 21 is punched in
the pack of laminations of the armature and the core, opening
21 extending n~rmally to the plane of the drawing. Opening 21
receives a connecting ~in or any other suita~le connecting
element.
Figs. 6 through 8 show yet another embodiment of the
electromagnet in which the structures of the core and the
armature are identical. The magnetic core or the armature is
designated by re~erence nurneral 28. Each includes three 1egs
2, 3 and 4. An inclinecl surface 22 i~ provided on the outer
leg 2. Surface 22 merges into a s~all horizontal end face 23.
Another inclined surface 25, merging into a hori~ontal stop ;
25, is provided on another outer leg 4. As shown in Fig. 8,
inclined surfaces 22 and 24, as well as end faces 21 and,
: :
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~2~3~8~5~ 1
stops 25, are shaped and dimensioned such that in assembly the
armature fits the magnetic core. As seen from Fig. 8 both
elements are pivotable one relative to another hy 180 once
about a horizontal axis and once about a vertical axis, The
middle leg 3 also has an inclined surface 26 which is punched
out during manufacturing of laminations. Inclined surface 26
is formed such that an air gap 27 remains between respective
surfaces 26 of the armature and the magnetic core when the
f latter are in superimposed position.
Fig. 9 shows the template with the positions of holes
for rivets as well as of rivets so selected that they can be
the same for all armatures and magnetic cores of alternating
current magnets and direct current magnets. In Fig. 9 the
alternating current core and the direct current core are
positioned one on the other. The alternating current core
corresponds to that of the embodiment of Figs. 4 and 5. The
direct current magnetic core in Fig. 9 corresponds to that of
Fig. 6. Inasmuch as the armature and the magnetic core have
the same structure the same positions of openings for rivets
for all armatures and cores result so that only a single
riveting tool or a single riveting ~achine is required for
producing said openings~
Figs. 10 through 12 depict yet another embodiment in
which the direct current core or armature is denoted by
reference numeral 29. ~he armature or magnetic core has three
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I
1234~i4
legs 30, 31 and 32 which are substantially longer when a lar~e
coil is re~uired. Inclined surfaces 33 and 37 and the end face
34 and stop 36 are formed in the same fashion as si~ilar
surfaces in Fig. 6. In the same manner the middle leg 31 has
an inclined surface 35. An air gap 3~ is for~ed between
opposing inclined surfaces 35 when the armature and magnetic
core are in assembled position as shown in Fig. 12.
Advantageously, laminations or sheets 15 are punched
~ out into a whole profile so that a mechanical aftertreatment,
particularly of opposing surfaces of the armature and the
core, could be omitted.
Fiq. 13 shows a further embodiment of the armature
or the magnetic core for direct current electromagnets, in
which similar reference numerals are utili7ed for the
components mentioned in connection with the previously
described embodiments. In this embodiment the r;liddle leg 3 has
two triangular or trapezoidal projections 45 and 46, which are
dimensioned so that the sum of the lengths of the outer
inclined surfaces 40 and 41 of these projections is equal to
the length of an intermediate inclined surface 39. Inclined
surfaces 39, 40 and 41 preferably extend at an angle 20
relative to the direction of movement of the armature, but
always at an acute angle. In this fashion a very large
effective magnetic surface in comparison with the size of the
armature or the core results, which is particularly
1234~54
- !
advantageous with three-dimensional small direct current
circuit breakers. ~ small stop 42 is provided on the middle
leg 3 laterally of projection 45. The trapezoidal shape of
each projection ~5, 46 results in ~lat horizontal end faces A3
and 44. The entire shape of middle leg 3 with the above
described surfaces ensures that during the assem~ly of the
armature with the magnetic core a small uniform air gap will
result between the respective opposing sur~aces. Due to such
structure of the middle leg 3 it is obtained that a pulling or
magnetic force of the electromagnet would act precisely in the
~iddle axis, that is in the direction of movement of the
armature. Thereby the armature during its stroke would be
provided with a satisfactory central guidance and friction of
the movable parts, particularly the armature relative to walls
or guidin~ surfaces, w~uld be reduced to minimal value. Both
outer legs 2 and 4 have trapezoidal projections 47 and 51 with
respective inclined surfaces 48 and 63 and horiYontal end faces
50. Inclined surfaces 48 and 63 extend at an an~le of
preferably 20 to the direction of movement of the armature.
Stops 49 and 64 are respectively provided laterally of
projections 47 and 51.
Fig. 14 illustrates yet a further embodiment of the
direct current electromagnet with the identically shaped
armature and magnetic core. he middle leg of the armature or
core is shaped si~ilarly to that of Fig. 13 so that this
1~3485~
embodiment has the same advantages as the structure o~ Fig. 13.
Projection 58 here is somewhat triangular while projection 59
is of trapezoidal shape. ~ stop 60 is provided laterally of
projection 58 and a small end face 61 is ~ormed on projection
58. A zigza~-shaped air gap 42 results between the respective
opposing surfaces of the armature and the core in assembly.
In Fig. 14 this air gap is shown enlarged; in other words the
armature and the core are not in their end position but are
rather spaced from each other.
In the embodiment of Fig. 14, a trapezoidal recess
52 is provided in one outer leg of the armature or the core.
This recess has two symmetrically inclined surfaces 65 and 66.
Another outer leg of the armature or the core has in turn a
trapezoidally-shaped projection 55 which fits into recess 52
of the opposite leg of the armature or the core, respectively.
Inclined surfaces 65 and 66 of recess 52 and the respective
surfaces of projections 55 advantageously extend at an acute
angle, preferably 20 to the direction of movement of the
armature. Laterally of projection 55 are stop surfaces 56 and
57 while laterally of recess 52 small end faces 53 and 54 are
formed. Since the above described oblique surfaces on outer
legs 2 and A are symmetrically shaped no force components in
the direction transversal to the direction of movement of the
armature would act in the region of the outer legs in case of
large effective magnetic surfaces so that a central guidance
~L234854
of the armature would ~e improved but friction would be
reduced.
~he armature and the magnetic core have in the
exemplified embodiment three legs. However, it is unde~-
standable that the invention is applicahle to electromagnets
having armatures and cores with two legs.
It will be understood that each of the elements
described above, or two or more together, may also find a useful
application in other types of electromagnets for electric
switches differing from the types described above~
While the invention has been illustrated and described
as embodied in an electromagnet for an electric switch, it is
not intended to be limite~ to the details shown, since various
modifications and structural changes may be made without
departing in any way from the spirit of the present invention.
Without ~urther analysis, the foregoing will so ~ully
reveal the gist of the present invention that others can, by
applying current knowledge, readily adapt it for various
applications without omitting features that, from the standpoint
of prior art, fairly constitute essential characteristics of the
generic or specific aspects of this invention.
What is claimed as new and desired to be protected by
Letters Patent is set forth in the appended clai~s.
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