Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates to materlals handling
and more particularly to rotary feeders useful in vacuum
applications.
BACKGROUND OF THE INVENTION
Various types of rotary feeders are known in the art
for differing applications. When used in vacuum applications,
for permittin~ ingress and egress of goods from a vacuum
chamber, conventional rotary feeders comprise a
circumferential seal which is designed to minimize the leakage
o~ air into the vacuum. Such seals are extremely cumbersome
and expensive and involve significant frictional drag on the
moving parts, and therefore require frequent and extensive
; maintenance.
The use of a rotary feeder of the above general type
in the context of a vacuum system having a sealing sleeve
filled with a condensi~le gas is described in Israel Patent
50398, published October 31, 1978, of David Reznick, one of
the inventors herein.
There has concurrently been described a rotary
feeder comprising an enclosure de~ining ~n inlet and an
outlet, a rotary feed member of generally cylindrical
con~iguration arran~ed for rotation about its axis of symmetry
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within the housing and sealing apparatus arranged for sealing
engagement with the rotary feed member at a location within
the enclosure correspondin~ to either or both of the inlet and
outl.et, whereby frictional engagement of the rotary feed
member with the sealing apparatus occurs only in the vicinity
of either or both of the inlet and outlet and not throughout
the enclosure or circumferentially of the rotary feed member.
In the apparatus concurrently described, the sealing
apparatus may be provided only at the outlet of the enclosure,
only at the inlet of the enclosure, or at both the inlet and
outlet of the enclosure.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved
vacuum system incorporating a rotary feeder and more
particularly a vacuum treatment system incorporating a rotary
feeder which is suitable, inter alia for vacuum applications
of the type described in the aforesaid Israel Patent 50398.
There is thus provided in accordance with an
embodiment of the present invention a vacuum treatment chamber
comprising an enclosure whose interior is maintained at
predetermined vacuum and temperature conditions, the enclosure
defining at least one access port, a rotary feeder disposed
within the enclosure and being maintained at the vacuum and
temperature conditions of the interior thereof and
communicatin~ with the access port via a conduit extending
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through the enclosure and filled with a condensible gas
substantially to the exclusion of atmospheric air, and sealing
apparatus coupled to the conduit and arranged ~or slicing
engagement with a relatively small portion of the periphery of
the rotary feeder, for providing communication between the
conduit and the rotary feeder while reducing the amount of
condensible gas permitted to enter the vacuum enclosure.
Additionally in accordance with an embodiment of the
present invention, the remainder of the rotary feeder is open
to the interior of the vacuum enclosure.
For the purposes of the present invention, a
condensible yas is defined as a gas which condenses under the
temperature and pressure conditions present inside the ~acuum
chamber. A ~referred condensible gas is steam.
Further in accordance with an embodiment of the
present invention, the vacuum enclosure may define inlet and
outlet ports, conduits associated therewith and first and
second rotary feeders associated with the respective conduits
and disposed within the vacuum enclosure.
The apparatus of the present invention has
significant advantages over prior art designs oE vacuum
chambers wherein the rotary ~eeder is disposed outside the
vacuum chamber. These advantages may be summarized as
Eollows: ;
a. Obviates the need for a housing surroundiny the
rotary feeder;
b. Enables the rotary Eeeder to be maintained at a
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uniformly low temperature, which was not possible in the
prior art due to the need to avoid condensation of the
condensible gas;
c. Obviates the need for vacuum sealing at the
axles of the feeder;
d. Enables simpler, lighter and less expensive
construction to be used since small forces produced by the
vacuum gradient are exerted thereon;
e. Reduces intake of atmospheric air to the vacuum
enclosure;
f. Facilitates access in the case of jamming;
g. Enables continuous cleaning of the feeder.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and
appreciated more fully from the following detailed description
taken in conjunction with the drawings in which:
Fig. 1 is a side sectional illustration of a vacuum
treatmeint chamber incorporating a rotary feeder constructed
and operative in accordance with a preferred embodiment of the
present invention;
Fig. 2 is a top sectional illustration of the
apparatus of Fig. 1, wherein the interior conveying apparatus
has been omitted for clarity;
Fig. 3 is a side sectional illustration of a rotary
feeder useful in a preferred embodiment of the present
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invention;
Fig. 4 is a sectional illustration of the apparatus
of Fig. 3 taken along the lines A - A thereof.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Reference is now made to Flgs. 1 and 2 which
illustrate in sectional illustration, a vacuum treatment
chamber incorporating rotary feeders constructed and operative
in accordance with a preferred embodiment of the presen~
invention.
The vacuum treatment chamber, indicated generally by
reference numeral 10 is constructed in a conventional manner
and is suitable for maintaining a vacuum of about 28mm Hg.
The vacuum chamber may be of any suitable configuration and
size and is preferably suitable for permitting manufacturing
processes, such as can sealing, exhaustion of air from fruit
tissues, etc. to be carried on therein.
Vacuum treatment chamber 10 is formed with an inlet
port 12 and an outlet port 14 which permit ingress and egress
of goods involved in a manufacturing process as well as a
communications port 18, which communicates with a vacuum pump
or other source of vacuum, for maintaining the desired vacuum
ln the interior of chamber 10.
According to an alternative embodiment of the
present invention, only a slngle port may be provided and this
port may serve as both an ingress and egress port. As a
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further alternative more than two ports may be provided.
According to a preferred embodiment o~ the pre~ent
invention at least one rotary feeder is located within the
vacuum chamber and is arranged for communication with a port
thereof via a conduit. In the illustrated embodiment, first
and second rotary feeders 18 and 20 are located within the
vacuum chamber 10. Feeders 18 and 20 communicate with
respective inlet and outlet ports 12 and 14 via respective
feeder conduits 22 and 24. Conduits 22 and 24 communicate
with the outside atmosphere. In order to minimize leakage of
atmospheric air into the vacuum chamber 10, conduits 22 and 24
are filled, via supply conduits 26 with a condensible gas,
such as steam, substantially to the exclusion of atmospheric
air, whereby entry of the condensible gas into the vacuum
chamber does not appreciably reduce the vacuum therein since
; the gas condenses under the temperature and pressure
conditions of the inside of the vacuum chamber.
Articles or goods for treatment are supplied via
conduit 22 to rotary feeder 18 by a conveyor 28, while treated
articles or goods may be removed from rotary feeder 20 by
gravity. Communication of goods within the vacuum chamber may
be provided by any suitable materials handling means, which
are illustrated for simplicity herein as conveyor belts 32.
According to one preferred embodiment of the
invention, the rotary feeders 18 and 20 as well as the
conveyors 32 are powered by power s;ources which are located
within the vacuum chamber, such as pneumatic or hydraulic
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motors, which are coupled to sources of motive power, such as
pressurized air or hydraulic fluid, via conduits 36 which pass
through the walls of the vacuum chamber 10.
Referring now to Figs. 3 and ~, it is seen that
S rotor 112 is of generally disk-like configuration and
comprises a pair of parallel circular side walls 114 and 116
which are mounted on a driving shaft 118, which is in turn
bearing mounted within vacuum chamber 10. It is appreciated
that the mounting of shaft 118 in vacuum chamber 10 need not
be a sealed mounting to minimize the amount of gas leakage as
in the prior art, since the entire assembly is located within
the vacuum chamber.
Rotor 112 also comprises an inner cylindrical wall
surface extending between side walls 114 and 116 and plurality
of fins 122 extending radially outward therefrom so as to
define sealed compartments 123, which are sized to contain
articles such as cans 124 which are sought to be fed by the
rotary feeder.
A sealin~ assembly 130 is associated with the inlet
opening 128. The sealing assembly 130 comprises a generally
arcuate sealing shoe 134, which is maintained in pressurized
contact with the periphery of the rotor 112 by means of an
elastic member 136, typically formed of a polymer, which is
disposed between the inside surface of a flared portion 132 of
the conduit and the outer facing surface of the sealing shoe
134.
The sealing shoe 134 is typically ~ormed of a
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material which is softer than the material from which the
rotor 112 is Eormed, such that rotation of the rotor 112
against the sealing shoe tends to cause wear in the sealing
shoe, which is relatively readily replaceable. Normally
grooves will develop in the sealing shoe, enhancing the
sealing provided thereby.
The sealing shoe is configured to be larger than the
outlet opening and to circumferentially surround it. I'he
sealing assembly 130 may thus be understood to provide an
effective fluid seal between the conduit 22 or 24 and the
in~erior of vacuum chamber 10. Furthermore, the configuration
of the shoe is such that a compartment of the rotor which is
open to the outlet opening is sealed from the adjacent
compartments which communicate with the interior of the vacuum
chamber 10. In practice, at least two compartments 123 and
three adiacent finds 122 are covered by shoe 134.
The operation of the rotary feeder described
hereinabove will now be reviewed briefly. As seen in Fig. 3,
~ cans, or any other suitable objects or bulk materials are
loaded in to the compartments 123, one can per compartment,
and, by rotation of the feeder rotor, then reach interior of
the vacuum processing chamber where they are transported by
conventional automatic materials handling equipment.
It will be appreciated by persons skilled in the art
that the present invention is not limited by the configuration
of the chamber or the rotary feeder, which are here shown in
an embodiment particularly suitable for loadin~ of cans. The
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present invention is not limited by the partlcular structure
shown and described hereinabove. Rather the scope of the
invention is deElned only by the claims which Eollow.
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