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Патент USA US2612575

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Sept‘ 30, 1952
Filed Oct. 3, 1946
0wEW,a W
‘Patented Sept. 30, 1952
Benjamin L. Binford, Chicyago,yIll., assignor to '
Magnetrol, Inc., Chicago, 111., a corporation of
Application October 3, 1946,,‘ Serial No. 701,017
2 Claims.’ (Cl. 200—87')
' This invention relates to magnetic control
in, the cover H. The hub portion [4 rotatablyf‘
mechanism and more particularly to a mecha
supports a base plate I5 which may be held in
nism employing electrical switches which are op_~v
erated magnetically in'accordance with changes
in a condition to be indicated or controlled.
' Cl
One of the objects of the invention is to pro
adjustedposition' on the hub by a set. screw 16.
The base plate I5 is formed with a threaded
opening I‘! at one ‘side for connection with an
electrical conduit and. can be rotated to bring the
vide a magnetic control mechanism, whichis
conduit and the wires therein into the base plate
extremely ?exible in use in performing a desired
at any convenient, position.
number and sequence of control operations.
The hub I4 ?xedly carries a nonmagnetic tube
According to one feature of the invention the 10V 18 which may be formed of brass or the like. As
mechanism may be built up by assembling a‘
shown, the tube extends up through the base to
plurality ‘of inter?tting control units, in a desired
terminatein a closed upper end and opens at its
Another object is to provide a magnetic con:
trol mechanism including a self-contained switch
assembly’ which can be easily and quickly in
stalled in various types of control installations.
‘ Still another object is to provide a magnetic
lower end intothe chamber Hi. When the base
is assembledv on the chamber, the armature i3
?ts loosely into the tube for vertical sliding
movement therein as the ?oat rises and falls.
'The tube [8 is adapted to carry one or vmore
switch units, as more particularly shown in Fig
ures 2 to 4. Each of the units comprises a gener
control mechanism in which a tiltable Switch is
connected to ?exible lead wires in such a way as 20 ally rectangular non-magnetic frame having an
to minimize flexing of the ‘wires and to maintain
end ‘portion 2] which is integral with a side wall
a substantial balance of the switch in all posi
22. At its lower edge the wall 22 is formed with
‘ '
Still another object is to provide a magnetic
control mechanism in which a tiltable switch is
controlled by a spring which is so arranged as
a downwardly extending skirtv portion 23 which
is offset outward from the upper part of the
wall and whichhas an open bottomed notch 24
therein. At its upper edge the wall 22 is notched
to maintain a substantially constant tilting force
or offset as indicated at. 2,5 for a purpose to ap.
on the switch in all positions thereof.
pear later. The opposite site of the frame, asv
The above and other objects and advantages
shown at 26, is connected by riveting or the, like
of the invention will be more readily apparent
to the end wall 21 and is relatively narrow. At
from the following description when read in con
the opposite, end, of the frame the wall 25 is bent
nection with the accompanying drawing, in
over to form a stop ?nger or arm 21.
Within the central part of the frame there is
Figure l is a vertical section with parts in ele
provided a split mounting block 28 adapted to be
vation of a control installation embodying the
35 drawn together by a screw 29 and‘ of a size _to
invention; and
receive the tube I 8. In mounting the unit on
Figures 2, 3, and 4 are top, plan, side, and end
the tube, the block 28 can be slipped over the
elevations, respectively, of a switch unit embody
tube and moved to the desired level, and the
screw 29 can then be tightened to hold the unit
As shown in Figure l, the installation is 40 in position on the tube. Preferably the lower
adapted to indicate or control the level of liquid
most unit is, closed at its bottom by a non-mag
ing the invention.
in a, boiler, tank or the like and comprises a level
netic plate 3| ?tting over the tube and held at
chamber [0 having top and bottom connections
the desired elevation ‘by a spacer 32.
through which it may be connected to the tank
or boiler so that the level in the chamber will be
the same as that in the tank or boiler.
y >
At one end the switch unit carries an insu
lating contact block 33 provided with a ‘plurality
of terminals for connection to the cable and to
the switches as described hereinafter. The ‘con
tact block may be separated by an insulating
chamber I0 is closed at ‘its top by a cover ll
formed with a central threaded opening for
mounting of the control unit. A ?oat I2 is
plate 34 which extends beyond the rectangular
mounted in the chamber and is connected to an 50 outline of the frame and is formed with notches,
elongated magnetic armature l3 to move the
as best seen in Figure 4, for the ?exible leads.
armature in accordance with level changes.
The magnetic control mechanism comprises
At the Opposite end the frame rotatab'ly sup
ports an axle 35 which carries a downwardlyex
a'base having a central hub portion 14 which is
tending arm 36. At its lower end the arm 36.v
adapted to be ?xedly threaded into ‘the opening 56 carries a permanent magnet 31 which is adapted
to move toward the tube 18 when attracted by
the armature and which normally occupies a po
sition spaced from the tube, as illustrated.
Movement of the magnet away from the tube
may be limited by engagement of the arm 35 Gr
with the stop ?nger 21.
The arm is formed with a bracket extension 38
According to one feature of
the invention the switch is carried by a support
ing plate 39 pivoted on the bracket 38 and ad
justable relative thereto through an adjusting
screw 4 i. In this way the position of the switch
can initially be set for any given installation to
compensate for slight angularity of the tube l8
with respect to the vertical and to insure proper
opening and closing of the switch.
mounted on a single tube l8 at points spaced
along the length thereof to perform different in
10 dicating or control operations at different points
in the travel of the ?oat. According to one fea
ture of the invention, the frames of the switch
units are so formed that they will inter?t and
can be mounted on the same tube relatively close
together in making up an assembly. As shown
in Figure 1, when the units are so stacked, the
positions of alternate units are reversed with re
As shown the mechanism embodies tiltable
mercury type switches 42 which may be either,v
' spect to each other.
single or double throw switches, as desired. The ».
switches are supported by supporting clamps 43
carried by the plate 39 and preferably lying above '
the pivotal axis of the arm, the bracket and the
plate. With this construction the entire arm,
bracket and plate assembly may .be balanced
about the pivotal axis to provide for easy and
constant operation at all times. ‘
anceto ?exure of the leads balanced about the
pivotal axis. Operation of the mechanism is,
therefore, not interfered with by the leads.
In installing a switch mechanism embodying
the invention, one or more switch units may be
which projects beyond the side 22 of the frame
to carry a switch.
minimum ?exing of the leads during tilting of
the switch and maintains the weight and resist
In this position the lower
edge'of the side wall 26 of the upper unit ?ts into
the notched or cut away portion 25 of the unit
beneath it while the offset skirt 23 of the upper
unit ?ts over the wall 26 of the unit beneath it.
The notch 24 is provided to receive the pivot
support carried by the wall-26 of the lower unit
so that the units can bestacked relatively close
together and will inter?t without interference
with desired movement'of the parts. When the
switch units are assembled on the tube, they
may be connected with cable wires brought in
through the opening I‘! in the base plate and
To turn the arm, bracket and plate assembly
to the position shown in which the magnet is
spaced from the tube, a spring 44 is provided.
According to the present invention a relatively
long tension spring is employed connected at
which extend up around the sides of the units.
The cable wires may be brought up along side
one end to a ?nger on the side 22 of the frame
the terminal blocks 33 and may be held in the
and at its opposite end to the plate 39. The con
desired location by ?anges 46 formed on the
nections are so located that asthe magnet moves 35 end walls 2| of the frames which engagev the
away from the tube toward the position shown,
cable Wires to hold them in positions where
the spring approaches a line through the ?nger
they. will not interfere with proper operation of
and the pivotal axis of the arm, bracket and plate
the switch mechanisms. The entire assembly
assembly. As this assembly is turned clockwise
may be covered by a cup-shaped cover 41 ?tting
to move the magnet toward thetube, as seen in .
against the base plate l5 and secured by a screw
Figure 3, the spring acts through an increasing
48 threaded into the upper end of the tube l8.
moment arm to vbecome increasingly effective.
When the cover-4'! is installed, it preferably ?ts
Therefore, the tilting forces exerted on the as
relatively closely against the ?anges 46 positively
sembly by the spring varies. for each position of
to con?ne thecable wires against tangling.
the magnet in such a manner that the total tilt
ing force on the assembly is substantially con
stant throughout the full range of movement.
Thus when the magnetis remote from the tube
While one embodiment of the invention has
been shown and described in detail herein, it will
be understood that it'is illustrative only and is
and its attraction for the armattu‘e is at a mini
invention, reference being had for this purpose
not intended as a de?nition of the scope of the
mum, assuming the armature to be in the ?eld .
of the magnet, the moment produced by the
spring on the arm 36 and bracket 39 is at a mini
mum. Similarly when the magnet is adjacent
the tube and its magnetic attraction is maximum
the spring moment is maximum. With this con
struction, a substantially constant and uniform
tilting force is produced in one direction or the
other depending upon whether or not the arma
ture I3, is in the ?eld of the magnet to. provide
a uniform and reliable operation substantially
insensitive to minor unbalance or vibration.
to the appended claims.
What is claimed is:
1. Magnetic control mechanism comprising a
non-magnetic frame having a terminal block at
one end and having one side formed with an
offset skirt to ?t over the other side of an under
lying mechanism when the frames are stacked
in reverse position, means in the central part of .
the frame to ?t over and secure the frame to a
tube, an arm pivoted at the other end of the
frame, a magnet carried by the free end of the
arm for movement toward and away from the
tube, a bracket connected to the arm overlying one
side of the frame, a switch carried by the bracket,
The switch 42, when installed in the vbrackets
43, is adapted‘to be connected to the terminal
block 33 by ?exible leads 45, as shown in Figure
and ?exible connections from the terminal block
1. As illustrated in this ?gure, the switch is a
_ to the switch.
double throw switch requiring three leads. As
2. Magnetic control mechanism comprising a
shown, the leads connect to the switch at points
non-magnetic frame, means on the frame to re
lying on a line crossing the pivotal axis of the
ceive a tube to secure the frame to the tube, an
assembly and symmetrically spaced about the piv
arm pivoted on the frame about an axis trans
otal axis. With this construction, each of the .70. verse to the tube length, a magnet carried by the
leads is of a slightly different length so that the
free end of the arm for movement toward and
connections cannot be confused. Furthermore,
away from the tube, a bracket connected to the
the leads extend from the switch generally paral
arm to move therewith,'a switch carried by the
lel to the line on which their points of connec
bracket, and a tension spring connected at one
tion to the switch lie. This arrangement involves ‘ end to the frame and at its other end to the
bracket, the latter connection being made at a
point between the pivotal axis and. the point of
connection of the spring to the frame, said‘ point
of connection to the bracket being displaced a
slight amount to one side of a straight line pass
ing through said axis and the point of connection
of the spring to the frame so that the spring will
approach said straight line as the magnet moves
away from the tube.
The following references are of record in the
?le of this patent:
Rutledge ________ __ June 21, 1927
Davis ____________ __ Sept. 6, 1932
Morris et a1 _______ __ Dec. 20, 1932
Van Vulpen et a1. .____ June 15, 1937
Shrode ____________ __ Jan. 3, 1939
Gross et a1. ____,____ June 10, 1941
Moore __________ __ Aug. 11, 1942
Beam ____________ __ Mar. 16, 1943
Thompson ________ __ May 4, 1948
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