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Патент USA US2117132

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May -1 0, 1-938.
Filed July 22, 1935
[[11]] [III]
BY 4. i?M
Patented 'May 10, 1938
Max Baermann, Jr., Cologne, Germany
Application July 22, 1935, Serial No. 32,878
In Germany July 23, 1934
4mm, (Cl. 175-367)
Thainvention relates to a releasable permanent any pro?le su?lciently to ensure the
passage of a
magnet holding device particularly for electric large
enough flux for holding.
lamps which will adhere in any position to ob
But a support or holder fitted with such strong I
jects made of ferro magnetic materials.
It is known to provide electromagnets in the magnets could only be lifted from‘ an object by
foot of an electric lamp but the use of such
electromagnets has in practice many disad
vantages. Direct current is necessary for their
excitation, and that, unless D. C. mains are
available, must be taken from a battery. When
there are D. C. mains they commonly have so
high a voltage that a magnet lamp supplied
directly from them is dangerous to use.
Where there is an A. 0. supply this danger may
be avoided by transforming down the voltage;
the use of great force. A further feature of the 5
invention therefore contemplates the provision
of a short circuiting device for the magnetic ?ux
which facilitates the removal of the holder from
an object to which it has been adherent. The
magnetic short circuit is preferably in the im
mediate neighbourhood of the pole pieces for ex
periments have shown that with such strong
magnets a short circuit is not always effective
enough if applied only to the rear part of the
magnet pole.
In accordance with the invention the two. pole
but then a recti?er is necessary for supplying
the electromagnet. So that ‘in both cases com
plex apparatus liable to go out of order is neces ‘ shoes are of U form with limbs of different
length and are arranged on the two sides of the
sary for the operation of a magnet lamp.
A further disadvantage of the knownlarrange
ment is that if the current fails, or falls oil’ on
account of faulty contact, defect in the rectifier,
or failure of the supply, the lamp no longer
adheres, and unless the lamp is otherwise su?l
ciently supported it falls.
These disadvantages are avoided in the present
invention by the use of permanent magnets of
so high a coercive force .as to ensure adherence of
the device to a support. A suitable material for
such permanent magnets is an alloy having a
coercive force of more than 240 and preferably
more than 300 Oerst'edt.
To give the support and holder maximum
utility a further feature of the invention con
templates the combination of magnets and pole
shoes in the shape of a horseshoe magnet so
that two similar ?at poles, preferably of prismatic
‘cross section, stand opposite one another, each
terminating in two similar projections bounded
on their ends by a plurality of mutually inclined
planes. This form of pole shoe has in the middle
of its contact surface a notch broadening outward
while the outer edges are bevelled oil’.
Such a
shape of pole face in combination with the horse
shoe form is of great importance as regards the
adherent power since two separate magnet poles
will almost always be able to seat themselves
simultaneously upon an object of whatever
form it may be. Other forms of magnet, for
instance, the iron clad magnet in which a central
pole is surrounded by an annular pole, do not
always enable both poles to contact with an ob
ject, moreparticularly if the latter has a curved
airface. But the horseshoe form with projec
tions bounded by slanting surfaces will suit almost
magnet with their shorter limbs applied to the
magnet and the longer limbs forming the pole 20
pieces, and the short-circuiting plate is ar
ranged at the curve of the pole shoes. In this
construction of the magnet limb a short-circuit
ing plate may be arranged on the rear side of‘
the pole pieces without impairing the short cir 25
cuiting action. The production of this form of
holder is simple, cheap and easy.
An electric lamp may be .attached to the
holder'in any suitable fashion as, for example, by
means of a wing nut.
But the holder may be 30
employed not only for supporting electric lamps
but also as a support or hanger for any objects
whatever. Where considerable strength is needed
the invention provides a flat plate in which sever
al separate permanent magnets are arranged one
beside the other with their unlike poles opposite.
To remove such a plate from an object to which
it-is adherent, or to remove objects from the
plate, the poles of the separate magnets must be
Such short-circuiting may be effected by move
ment to and fro of a short-circuiting armature at
the rear of each magnet, preferably so that the
several armatures move in succession and not
simultaneously to lessen the power needed. For
this purpose the armatures are preferably con
nected with cams upon a common shaft so ar-.
ranged that when a particular position is reached
all the armatures are freed and applied to the
poles of the magnets. Such an arrangement is 50
especially of advantage for magnets carried in a
plate andhaving U-shaped pole shoes since the
short-circuiting armatures may without detri
ment to the short-circuiting e?'ect be applied to
the rear faces of the pole ends.
Instead of effecting the short-circuiting by
means of separate armatures it may be e?ected
by a leaf spring which in the short-circuiting
position contacts with all poles and is pressed
away from thempllya cam or the like separating
from them one after the other owing to its elas
The accompanying drawings show examples of
construction of the invention.
1 I
Figure 1 is a vertical longitudinal section
magnets. Figures 3 and 4 illustrating this mech
anism are of a diagrammatic character, but those
skilledin the art will readily understand how to
shape the cams with the necessary dwell to cause
the armatures to be applied in succession, each
armature then remaining-in engagement how
ever until all are engaged.
through a holder with U_-shaped pole shoes.
Figure 2 is a detail end view showing the form
or the pole pieces of Figure 1.
Figure 3 is a vertical section through e-plate
ill with inset magnets and with armatures actuated
by a cam shaft.
Figure l is a view" at right angles to
section on the line Elf-IV of Figure
cams 30 upon a. common shaft 29, the cams being
of such form that on turning the shaft the arma
tures are lifted in succession from the magnets
and in an end position are all applied to the
, Figure
oset5 magnets
is a vertical.Winch
separatea mag
Alternatively, as
shown in Figure 5, short-circuiting may be ef
looted by a spring 3i which in the short-circuiting
position contacts with all the magnets. Here
again the figure is diagrammatic and in practice
the spring 6 might need to be made thicker at
any rate in the parts forming the actual arma
tures, to c
y the
pressed dot» i '1;
"""gure 6 is a plan of the plate.
the construction of holder shown in Figure
1 two iii-shaped pole pieces ‘[3 with limbs of un
equal length are secured by their shorter limbs
M to the bar magnet‘ l5 by means of a bolt l6,
while the longer limbs l1 form the pole pieces.
to eparate from the several
in succession.
F. claim:
1. releasable permanent magnet holding de
vice comprising a permanent magnet, iii-shaped
polev shoes having limbs of unequal length, the 25
shorter limbs being applied to the ends of said
magnet, a short-circuiting armature, and means
Each pole shoe l3 terminates in two projections
for bridging said armature across the bends oi
he shcrt-circuited by a leaf spring.
l l bounded by inclined surfaces so that between
30 the projections there is a notch broadening out
ward, while the outer edges of the projections
are bevelled. This form of projection enables the
device to contact sufficiently not only with con
the pole shoes and removing it therefrom.
2. A releasable permanent magnet holding de 30
vice comprising a non-magnetic plate, a plurality
of permanent magnets mounted in said plate,
an armature for each magnet movable with re
cave and'jcpnvex surfaces but also with profiles spect to said plate into and out of shortecircuiting
35 of almost any form. The short-circuiting plate ' position relatively to its magnet, a shaft, and cam 35
I9 is applied to the ?attened bends l8 oi the pole means thereon co-operating with the said arma
tures upon rotation of the shaft to remove them
shoes l3. ,When the holder is required to ad
here to an object of magnetic material this plate successively from their magnets.
3. A releasable permanent magnet holding de
is turned by means‘oi the bolt 28 attached to it
and so lifted from the pole shoes by the action
of a pin it upon the curved surface oi’ the guide
bush 22. A thumb piece 23 serves for turning the
bolt to. The guide bush 22, the bolt 2e and a
casing 2t surrounding the whole device are made
oi non-magnetic material such as brass. On the
pole piece side the device is protected irorn in
gress of ‘iron particles and dirt by a plate 25 oi’
non-magnetic material such as brass.
When large surface is required to which ar—
547) .tioles are to adhere or when greatstrength is
necessary as, for instance, in chucks, a number
oi adherent devices 2? may be mounted in a
plate it or non-emagnetic material such as brass,
their pole shoesloeing oi’ the form shown in Flg==
Mi are l. The several armatures 28 are actuated by
vice comprising a non~magnetic plate, a plurality 40
of permanent magnets mounted in said plate
with their poles in one
a spring secured to
said plate and lying along the line of poles, and
means for pressing _,the end of said spring away
from said poles so that said spring separates 45
from the several poles in succession.
‘l. A releasable permanent magnet holding de
vice comprising a permanent magnet, U shaped
pole shoes having limbs of unequal length, the
shorter limbs being applied to the ends of said
magnet, a'siiort circuiting armature, and means
including a rotatable shaft and a cam for bridg
ing said armature across the bend of the pole
shoes and removing it therefrom;
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