Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
It is well-known in the art to provide automatic door
closure systems for public buildings whereby fire doors inter-
connecting various parts of a building are normally in the open
position and retained in that position by means of an electro-
magnetic device comprising a wall-mounted electromagnet and an
armature means for the electromagnet which is mounted on the
door. With the door in the open position, the armature element
on the door is brought into juxtaposition with the electromagnet
on the wall, and the door is held open as long as the electro-
magnet remains energized. In the event of a fire, for example,
the electromagnets for the various doors can be selectively or
all de-energized, thereby permitting the corresponding doors to
swing shut by means of associated door closure means.
It is necessary, of course, that the door, when held in
the open position, provide for the armature element to be brought
into a position where it is exactly flush with an element forming
a part of the wall-mounted electromagnet. often this is
accomplished by providing that the armature element itself be,
in effect, loosely supported on a mounting bracket secured to
the door. As a result, whenever the door is opened, the armature
element is brought into physical contact with the electromagnet,
and the loose fitting of the armature element upon its associated
mounting bracket then permits it to assume a position where it
is flush with the associated element on the wall. It has been
found, however, that the manufacture of such devices entails a
considerable amount of cost, resulting principally from the
difficulty of properly assembling the various elements so as to
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provide the desired degree of freedom of the armature element
relative to its supporting bracket.
Summary of the Invention
It is the object of the present invention to provide a
door-mounted armature means for an electromagnetic door closure
apparatus comprising a door-mounted bracket and with a pivotally
mounted armature element secured thereto. The securing means
for the armature element comprises a flange on the armature
element defining therein an aperture and a bifurcated portion on
the door-mounted bracket capable of receiving the flange between
the opposing legs of the bifurcated portion. The distance between
the opposing faces of the leg portions of the bifurcated portion
is substantially greater than the thickness of the flange so that
the leg portions do not restrict the freedom of movement of the
armature element.
The fastening means for the armature element comprises
a threaded bolt passing through aligned apertures in the opposing
legs of the bifurcated portion and with such bolt passing through
the aperture in the flange comprising a part of the magnet arma-
ture. A pair of nylon bushing elements each having a generallyhemispherical outer surface is provided to permit a substantial
degree of freedom of movement of the armature element while yet
permitting adjustment of the frictional resistance so that the
armature element will retain the position to which it is last
operated and thereby maintain its flat outer surface perfectly
flush against the wall-mounted electromagnet.
Brief Description of the Drawings
In describing the invention, reference will be made to
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the accompanying drawing in which:
Figure 1 diagrammatically illustrates an electromagnetic
door system employing the door-mounted armature means of the
present invention;
Figure 2 illustrates in perspective form the door-
mounted armature means of the present invention and also the wall-
mounted electromagnet;
Figure 3 illustrates in perspective the several
elements comprising the door-mounted armature means;
Figure 4 is a plan view of the armature means of this
invention; and
Figure S is a side view of the apparatus of Figure 4.
Detailed Description of the Preferred Embodiment
Figure l comprises a diagrammatic illustration of an
electromagnetic system for the control of various doors in a
building. A plurality of doors 10 is shown, each provided with
a closure means 12 normally acting to urge each door 10 to a
closed position with respect to the door frame provided in wall
14. Mounted on each door 10 is a magnet armature means 16 which
i8 in juxtaposition with an electromagnet means 18 securely
mounted to wall 20. A power supply 22 provides energization over
wires 24 for normally energizing each of the electromagnet means
18 to thereby retain each door 10 in the open position. However,
in the event of the detection of, for example, a fire by the
fire detection system 26, the power supply 22 de-energizes wires
24, thereby releasing electromagnet means 18 so that each door
can then be swung to its closed position.
The wall-mounted electromagnet means of the invention
is shown at 26 in Figure 2. This electromagnet means 26 is
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provided with a flat circular outer surface forming opposed
magnetic poles 28 and 29 of an electromagnetic clrcuit. The
door-mounted armature means of the invention i~ also shown ln
Figure 2 and comprises a mounting bracket 30 as well as an
armature element 31.
Figure 3 illustrates in greater detail the door-
mounted bracket 30 as comprising a bifurcated portion including
two opposed leg portions 32 and 34. Both of the leg portions
define axially aligned through bores 36 and 38 respectively,
the upper bore 36 belng threaded so as to threadably engage
with the threaded end of a bolt 40 which can be inserted into
the aligned apertures by passing such bolt together with the
cooperating unit 42 upwardly through the bottom of bore 38 and
then screwing the bolt 40 into the threaded aperture 36. The
nut 42 is provided with a central aperture therein which is
sufficiently large so as to be slidable along the shaft of
bolt 40. Thus, preferably the nut 42 does not have internal
threads engaging with the threaded end Or bolt 40 but iB rather
readily slidable along the bolt.
The armsture element 31 is provlded with a flange
portion 44 having a cylindrical aperture 46 formed therein. The
diameter Or this aperture 46 is slightly in excess of that of
the cylindrical portion 48 Or each bushing 50. In addition to
having the dylindrical portion 48, each bushing is provided with
a generally hemispherical outer surface 52 and also deflnes a
central bore 54 therethrough which is tapered as shown in the
cross-sectional view of Figure 5, having a diameter at its
cylindrical end which is only slightly larger than the diameter
of bolt 40 but having a significantly larger dlameter at its
other hemispherical end.
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The assembly of the variou~ parts of the armature
means is shown in Figure~ 4 and 5. To assemble the mechanism,
the two bushings 50 are inserted into opposlte sides of the
aperture 46 in flange 44, and thls assembly 1~ then placed
between the two opposed legs ~2 and 34~ Thereafter, the nut
42 ls placed upon bolt 40, and thls combination of elements is
lnserted into the aperture 38 from below and with the threaded
end of bolt 40 then screwed into the threads of aperture 36.
As the bolt is threaded further into the threaded aperture 36,
greater pressure is exerted by the upper end of nut 42 against
the lower one of the bushings 50 80 that both of these bushings
are squeezed together and the frictlonal resistance to movement
of flange 44 is thereby increased. The tapered diameter of the
bushings 50 permits a substantial degree of movement of
armature element 31 about an axis at right angles to bolt 40,
and of course there is an even greater degree of freedom of
movement of armature element 31 about the axls Or bolt 40 as is
more clearly illustrated in Figure 4.
It will thus be apparent that the pre~ent inventlon
provides a means whereby an armature element may be ad~usted to
any deslred position and yet be frictionally restralned from
moving rrom that posltlon once adJusted. Thls ad~ustablllty is
provlded by a very simple arrangement of parts which facilitates
thelr convenlent and qulck assembly.
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