Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a material sensing switch and
more particularly to an improved material sensing switch which
is ideally suited for use in dusty conditions such as bins,
tanks, cement silos, etc,
Many material sensing switches have been previously provided
but none has met with considerable success d~e to the environment
in which they are normally used to sense the presence or absence
of material. Material sensing switches are commonly used in
bins or ~he like to sense the presence or absence or material at
a particular level within the bin. It is essential that a switch
be provided which will function in dusty conditlons and which will
not create dangerous and hazardous sparks. It is also essential
that the switches be comprised of a material which will not be
damaged by the corrosive nature of the materials being sensed.
A further disadvantage in the prior art switch d~vices`is
that the switches are not convenient to mount nor are they
easily serviced~
Therefore, it is a principle object of the invention to
provide an improved material sensing switch.
A further object of the invention is to provide a material
sensing switch which is durable in use.
A further object of the invention is to provide a material
sensing switch which will not be damaged by the corrosive pro-
perties of the material being sensed.
A still further object of the invention is to provide a
material sensing switch including means fGr adjusting the
pressure required to activate the switch.
A still further object of the invention is to provide a
material sensing switch which is economical of manufacture.
These and other objects will be apparent to those skilled
in the art.
The present invention is intended to overcome the short-
comings of the prior art and to achieve the foregoing objects
and other advantages by providing a material sensing switch
assembly comprising, a cylindical body means having first and
second ends, and a backing plate means removably closing the
0~5
~irst end to define an interior compartment between the backin~
plate means and the wall. Connecting means secure the said body
means to a support means and the second end of the body means is
closed by a wall means having inner and outer surfaces, the wall
means having a first opening formed therein. Switch means are
secured to the body means within the interior compartment adjacent
to the inner surface of the wall means, said switch means having
a switch actuator extending outwardly through the first opening
o~ the wall means. A movable pressure plate means is positioned
at the second end of the body means at the outer surface of the
wall means for engagement with the switch actuator to activate
the switch means when the pressure plate is moved towards the wall
b~ pressure exerted thereon. A flexible member operatively and
removably secured to the second end of the body and covering the
press`ure plate has means securing the flexible member to the
body means. The wall means has a second opening formed therein
and has a post means on its inner surface which has a longitudinal
base formed therein communicating with the second opening. ~n
elongated spring means is positioned in the base and the second
opening and has one end in engagement with the pressure plate
to normally urge the pressure plate outward from the wall and the
switch actuator. An adjustment screw is threadably mounted in
the bore having one end in engagement with the other end of the
spring means whereby the pressure exerted by the spring means
on the pressure plate may be selectivQly varied by rotation
of the screw relative to the post. The adjustment screw being
accessible for adjustment upon removal of the backing plate.
The first opening may comprise a switch opening and the switch
means may be positioned adjacent to the switch opening, and a
sealing compound used in said interior body compartment to at
least partially embrace said switch means to seal the switch
opening and maintain the switch means in position.
This invention consists in the construction, arrangements,
-2a-
and combination of the various parts of the device, whereby the
objects contemplated are attained as hereinafter more fully set
forth, specifically pointed out in the claims, and illustrated
in the accompanying drawings in which:
Fi~ure 1 is a perspective view of the switch of this inven-
tion:
Figure 2 is an exploded view of the switch of this invention:
Figure 3 is a sectional view seen on lines 3-3 of Figure 1:
Figure 4 is a plan view of the assembly with the backing
plate removed and with the poured epoxy being cut away to more
fully illustrate the invention; and
Figure 5 is a plan view of the assembly with the outer ring,
flexible member and pressure plate removed.
The material sensing switch of this invention is referred to
generally by the reference numeral 10. Switch 10 includes a body
12 having ends 14 and 16. Body 12 is provided with a flange 16
extending outwardly there~rom at end 14 for mounting the switch
to a supporting structure.
Body 12 is provided with a wall nlember 18 spaced inwardly
of end 16 and which has a rectangular opening 20 formed therein.
Wall 18 is also provided with a circular opening 22 formed there-
in for a purpose to be described in greater detail hereinafter.
Body 12 also includes a recessed portion extending inwardly into
end 16 which defines an annular shoulder 26 positioned at the
periphery of wall member 18. A plurality of threaded openings
28 are provided in annular shoulder 26.
A plurality of spaced-apart posts 30 extend from the inner
surface of wall member 18 at opposite sides of the opening 20.
The numeral 32 referes to a conventional micro-switch which is
positioned in opening 20 and which has a pair of spaced-apart
openings 34 and 36 extending therethrough. Switch 32 is initially
maintained in position by means of cotter keys 38 threadably se-
cured to the posts by screws 33 and extending through the openings
s
34 and 36. The numeral 35 refels to a hardened epoxy material
or compound which is poured in the interior of ring 37. Epoxy
35 covers the screws 33 to maintain the micro-switch 32 in
adjustment and in position. The epoxy also forms the function
of sealing the plastic bod~ to the micro-switch 32 to form a
barrier between the front of the body and the interior electri-
cal courts.
Opening 22 communicates with a bore 40 formed in post 42
which extends from inner surface of wall 18. Spring 44 is
received by opening 22 and bore 40. Adjustment screw 46 is
threadabl~ mounted in bore 40 for selectively varying the posi-
tion of the spring 44 within opening 22 and bore 40. Backing
plate 48 selectiveIy closes end 14 by means of screw 50 extend-
ing through backing plate 48 and into threaded openings 52 formed
in flange 16. The numeral 54 refers to a pressure plate which
is positioned adjacent the outer surface of wall 18 inwardly of
the annular shoulder 26. Pressure plate 54 i5 adapted to engage
the plunger or switch actuator 56 extending from switch 32. A
flexible member 56 preferably comprised of a rubberized-nylon
material is positioned within end 16 of body 12 and covers the
annular shoulder 26 and backing plate 54. Flexible member 56 is
held in position by a base ring 58 by means of screws 60 extend
ing through ringe 58, flexible member 56 and into the threaded
openings 28.
In operation, the switch 10 could be mounted in a storage
bin or the like by means of bolts extending through the openings
62 in flange 16 so that flexible member 56 would be engaged by
the material within the bin. If switch 32 is normally open,
pressure of the material against the flexible member 56 will
cause pressure plate 54 to move plunger 56 inwardly into the
switch 32 so that the switch 32 will be closed thereby activat-
ing some form of signal device such as a light, buzzer, etc.
,
:. :
connected to the switch which will indicate that the material in
the bin or the like has reached the level of the switch 10. The
adjustment screw 46 permits the seLective adjustment of the
resistance of the spring 44 against the inside surfaces of the
pressure plate 54. In other words, if adjustment screw 46 is
threadably moved inwardly into the bore 40, the spring 44 will be
compressed between the inner end of screw 46 and pressure plate
56 to increase the yieIdable resistance against the inward move-
ment of the plate 56 so that greater pressure on pressure plate
iO 54 to activate the switch 32.
Preferably, backing pla~e 48 and body 12 are comprised of
a plastic material to prev~nt the corrosive material being sensed
from damaging the assembly. The rubber-nylon construction of
flexible member 56 and the nylon construction of the ring 58 pre-
vents the corrosive material being sensed from damaging the com~
ponents. The base ring 58 and its relationshiP to the fle~ible
member 56 as well as the pressure plate 5~ insures that dust will
not enter the interior of the switch. The switch is easily mounted
within the bin and is easily serviced due to the construction of
the assembly. If flexible member 56 should become torn, the
epoxy material 35 prevents dust, moisture, etc. from passin~
through opening 20 into the interior electrical compartment.
Thus it can be seen that the invention accomplishes at least
all of its stated objectives.
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