Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: FEEDER FOR MOIST FISH FEED
FIELD OF THE INVENTION
This invention pertains to apparatus for feeding fish in a fishpond or
in a fish farming sea cage, and more particularly it pertains to an apparatus
for screening and delivering moist fish feed pellets in an intermittent or
pulsating mode.
BACKGROUND OF THE INVENTION
Many fish growers believe that moist feed pellets are better than dry
pellets to nourish a school of fish. The moist pellets sink quickly below the
water surface where they are available to the younger and less vigorous
fish. This feature is believed to be particularly advantageous when starting
the rearing of a stock of young fish.
The handling of moist feed pellets, however, represents some
difficulties. The moist material tends to form lumps that cannot be
processed through a mechanical feeder. The moist material tends to stick
to machine parts and to build up in the machine passages to clog the
machine.
Another difficulty with the handling of moist fish feed is found in
the separation of the fine particles from the moist pellets. It has been
observed that a batch of fish feed can contain over 10% of fine particles
and fragments of broken pellets. These fine particles and fragments,
referred to as feed waste, are generally not eaten by the fish and sink
through the mesh at the bottom of the sea cage. These particles accumulate
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over the bottom of the body of water under the sea cage and rot with fish
excrement. Such accumulation of decaying material under the sea cage can
promote the development of disease agents and cause other discomforts to
the fish being reared at that location. Therefore, a fallow period is normally
provided between growth periods to allow for natural cleansing of the cage
site.
It will be appreciated that there are incentives for fish growers to
reduce the pollution generated under a sea cage from the accumulation of
waste feed, and by the same action to reduce the extent of the fallow
periods. There are also economic incentives to separate and collect the feed
waste at the feeder for later recycling into whole feed pellets. These
incentives impose a heavy demand on the existing feeders. This demand
is believed to be greater than the capacity available in the prior art.
Some of the prior art feeders produce a constant flow of feed
material. Examples of these apparatus are described and illustrated in the
following documents:
US 4,832,538 issued on May 23, 1989 to Steve Bullerman et al.;
US 4,984,536 issued on Jan. 15, 1991 to James W. Powell et al.;
US 5,076,215 issued on Dec. 31, 1991 to Ning C. Yang, and
US 5,337,698 issued on Aug. 16, 1994 to Ronald L. Widmyer.
Each of these apparatus uses a feed screw or a rotary valve to deliver
a constant amount of feed material to the inlet of a venturi eductor, where
the feed material is blown away in an air stream.
In another apparatus of the prior art, there is provided a system to
recover feed waste falling at the bottom of a sea cage. The feed waste is
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then available for recycling. This system is described in the following
document.
CA 2,145,338, a patent application published on Sept. 24, 1996.
In another type of apparatus, an endless belt conveyor with spaced
apart flights is used to feed the material out of a hopper and into a fish
pen.
A limited amount of material is carried out by each flight, and for this
reason, these apparatus are capable of producing an intermittent flow of
fish feed. Examples of equipment belonging of this group are described in
the following documents:
US 848,101 issued on Mar. 26, 1907 to H. S. Hale, and
US 5,842,303 issued on Dec. 1, 1998 to George Abraham et al.
Because of their intermittent feed characteristics, the apparatus in
this last group are believed to be efficient in delivery moist feed material
without clogging. However, the designs of these apparatus do not offer any
suggestion to recover the feed waste, or to deliver the feed pellets in an air
stream. The apparatus from the first group using blowers do not offer any
suggestion to prevent clogging when processing moist feed material, or to
separate the feed waste from the whole feed pellets. Generally, the
apparatus of the prior art have been used with limited success with moist
fish feed, and therefore numerous fish growers still have recourse to hand
feeding, despite the high labour cost of this practice.
As such, it may be appreciated that there continues to be a need for
a new and improved apparatus to deliver moist fish feed in a reliable
manner without clogging and with the ability to screen and recover the feed
waste for recycling.
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SUMMARY OF THE INVENTION
The present invention provides a feeder having screening abilities,
an intermittent feed mode and an articulated air delivery system for
dispensing moist feed pellets over a wide area of a fishpond or a sea cage
with minimum or no clogging thereof.
In accordance with one feature of the present invention, there is
provided a feeder for dispensing moist feed pellets to fish in a fish farming
installation. The feeder comprises a feed storage hopper, a screen group to
separate the feed material into edible-size pellets and feed waste, and a
conveyor for conveying the feed material from the hopper to the screen
group. The feed waste is collected in a receptacle for later recycling
through a feed pellet extruder. The feeder also has an air delivery system
for aspiring the edible-size pellets from the screen group and for delivering
the pellets into an air stream directed toward a fish pen. Most importantly,
the conveyor is a belt type conveyor with spaced-apart flights, providing
this feeder with the ability to dispense discrete amounts of fish feed in an
intermittent feed mode from the hopper, through the screen group and into
the air delivery system.
One advantage of the intermittent feed mode is that it greatly
reduces the sticking of moist feed material to the machine parts. It is
therefore possible to screen the feed material to an extent which is unheard
of with feeders of the prior art. During tests in an actual installation, a
total
of 10.9% of the feed material has been recovered as feed waste. This
material was re-extruded and reuse. As one can imagine the recovery of
this feed waste represents a substantial saving in feed cost to the fish
grower.
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In accordance with another feature of the present invention, the
screen group comprises a primary and secondary screens, each having a
different bar spacing, and a reciprocating mechanism affixed to the screens
for vibrating the screens with different stroke lengths corresponding
substantially to their bar spacings. This feature contributes to an efficient
screening of the feed material without applying unnecessary stress on the
feed pellets.
In yet another feature of the present invention, the air delivery
system comprises a venturi eductor, a nozzle and an articulated support
assembly for supporting and moving the venturi eductor and the nozzle
from side to side and up and down. The air delivery system also comprises
an accept belt conveyor having a discharge end. The venturi eductor
comprises an inlet pipe having a mouth opening over the discharge end of
the accept conveyor for aspiring feed pellets from the discharge end. The
mouth opening has a D-like shape comprising a straight edge being
contiguous with or near the surface of the conveyor. The articulated
support assembly has a horizontal axis of articulation aligned with the
straight edge and a vertical axis of articulation passing through a mid-point
on the straight edge. This air delivery system is particularly appreciable for
delivering feed pellets in many directions without losing the suction at the
mouth opening of the inlet pipe.
In yet another aspect of the present invention, the articulated support
assembly is movably mounted on the frame of the feeder and is adjustable
in up and down directions to reduce or increase a gap between the straight
edge of the mouth opening and the conveyor belt.
Other advantages and novel features of the present invention will
become apparent from the following detailed description of the preferred
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embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the present invention is illustrated in the
accompanying drawings, in which like numerals denote like parts
throughout the several views, and in which:
FIG. 1 is a perspective view of an installation of the feeder for moist fish
feed according to the preferred embodiment of the present
invention;
FIG. 2 is a partial longitudinal cross-section view of the preferred feeder;
FIG. 3 is a perspective view of the primary screen and the lump breaker
mounted in the screen group of the preferred feeder;
FIG. 4 is a partial side view of the reciprocating mechanism used for
imparting reciprocating movements in the primary and secondary
screens;
FIG. 5 is a perspective view of the accept conveyor and the air delivery
system;
FIG. 6 is a partial top view of the accept conveyor and the air delivery
system;
FIG. 7 is a partial longitudinal cross-section view of the accept conveyor
and the air delivery system, and
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FIG. 8 is a cross-section view of the accept conveyor and the inlet pipe, as
seen along line 8-8 in FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and will be described in details
herein one specific embodiment, with the understanding that the present
disclosure is to be considered as an example of the principles of the
invention and is not intended to limit the invention to the embodiment
illustrated and described. Although the feeder according to the present
invention has been used successfully with moist pellets, it has also been
used with excellent results with dry pellets. Therefore it is not the intent
of
the following description to limit the application of this feeder to moist
feed
material only.
Referring to the FIG.1, the feeder for moist fish feed according to
the preferred embodiment 20 comprises broadly, a hopper 22 in which
moist feed material is loaded. An endless main belt conveyor 24 is
mounted along an incline adjacent the hopper 22, and constitutes one side
of the hopper 22. Under the discharge end of the main conveyor, there is
provided a screen group 26 wherein the fish feed material is separated into
whole feed pellets and recoverable feed waste. The whole feed pellets are
fed into an accept conveyor 28 where they are picked up by a venturi
eductor 30 and blown away through a nozzle 32 into an air stream created
by a blower 34 connected by the hose 36 to the venturi eductor 30. The
feed waste is collected in a waste receptacle 38 under the screen group 26.
The feed waste is therefore available for re-extruding into whole pellets
through a pelletizing machine.
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In the preferred feeder 20, the venturi eductor 30 and nozzle 32 are
movable form side to side and up and down by means of an articulated
support assembly 40. The venturi eductor 30, the nozzle 32, the blower 34
and hose 36, and the articulated support assembly 40 constitute the air
delivery system 42 of the preferred feeder 20.
The hopper 22 has a grate 44 over a portion thereof to assist an
operator in breaking the odd chunks of feed material into screenable lumps.
There is also provided an adjustable gate 46 above the main conveyor 24
to regulate the amount of feed material being carried by the main conveyor
24.
Referring now to FIGS.1-4, the processing of feed material will be
explained in details. The main conveyor 24 has an endless belt 50 driven
by a motor 52. The motor 52 is connected to the upper shaft of the main
conveyor 24 and is partly illustrated in FIG. 1. The endless belt 50 has a
series of spaced-apart flights 54 to carry discrete amounts of feed material
such that this feed material can be fed through the screen group 26 in an
intermittent feed mode.
The screen group 26 comprises a frame 56, a primary screen 58 and
a secondary screen 60. Both screens are movably mounted into the frame
56. The primary screen 58 has screen openings to prevent the passage of
large pellets and lumps, while letting the edible-size pellets and feed waste
there through. A preferred bar spacing in the primary screen S8 is between
about 1/2 inch and about 5/8 inch. The secondary screen 60 has openings
to prevent the passage of the edible-size pellets and to let feed waste there
through. A preferred bar spacing in the secondary screen 60 is between
about 1/4 inch and about 3/8 inch.
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Each of the primary and secondary screens 58, 60 is mounted on two
rails 62 as illustrated in FIG. 3. These rails 62 are movably supported
through linear bearings 64 mounted in the frame 56 of the feeder, as partly
illustrated in FIGS.1 and 2. These linear bearings 64 and their mountings
are not illustrated in details herein because they do not constitute the
essence of the present invention and are well known to machine designers.
Both the primary screen 58 and the secondary screen 60 are movable
back and forth and in opposite directions through their respective linear
bearings 64, by means of a reciprocating mechanism 70. In the preferred
feeder, this mechanism 70 is mounted at the far end of the screens when
seen in the side view of FIG. 2. This mechanism consists of a motor 72,
an eccentric shaft 74 driven by the motor 72 and affixed to a drive link 76.
The eccentric shaft 74 has an offset dimension of about 1/8 inch. The drive
link 76 is pivoted to a tilt bar 78 which in turn is pivoted about its centre
to
a bracket 80 mounted to the frame 56. Upon the ends of the tilt bar 78,
there is provided a pair of driven links 82 pivoted thereto and to one of the
primary and secondary screens 58, 60. A rotation of the drive motor 72
causes the tilt bar 78 to oscillate back and forth about the pivot 84 in the
bracket 80, and causes both screens 58, 60 to move back and forth along
their rails 62.
The positions of the mountings of the driven links 82 along the tilt
bar 78 are preferably selected to provide a displacement in the primary
screen 58 which is about twice as long as the stroke length of the secondary
screen 60. This feature is advantageous for causing movements in the
screens which correspond more or less to their respective bar spacings. The
different stroke lengths of the screens are believed to contribute to an
efficient screening of the feed materials while not subjecting the feed
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pellets to unnecessary stresses.
A counterweight 86 may be provided at the lower end of the tilt bar
78 to overcome the effect of the inertia of the reciprocation mechanism 70
on the drive motor 72.
Referring back to FIGS. 2 and 3, the primary screen 58 is inclined
downward away from the main conveyor 24. A lump breaker grate 90 is
affixed to the frame 56 over the lower end of the primary screen 58 and
forms with the lower end of the primary screen 58 an acute angle 'A' of
about SO degrees. The lump breaker grate 90 remains fixed relative to the
frame 56 and to the primary screen 58.
In use, the feed material containing lumps falls down over the
primary screen 58 as indicated by arrow 92 in FIG. 2. The whole pellets
pass through the screen 58 and the lumps are deflected against the lump
breaker grate 90 where they are ground against the lump breaker grate 90
by the reciprocating action of the primary screen 58. The lumps are ground
until broken down in smaller pieces capable ofpassing through the primary
screen 58.
The secondary screen 60 is set below the primary screen 58 and is
sloping downward in the opposite direction relative to the primary screen
58. These opposite inclinations of the screens cause a sudden change of
direction in the movement of the feed pellets, and enhance the separation
of the feed waste from the feed pellets.
As can be seen, the inclination of the secondary screen 60 causes the
edible-size pellets to fall into the accept conveyor 28. The secondary
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screen 60 acts as a deflector to convey the feed pellets into the accept
conveyor 28 as indicated by arrow 94. The feed waste passing through
the secondary screen 60 is collected in a waste receptacle 38 below the
secondary screen 60 as indicated by arrow 96.
In use, the feed material 100 is taken up by the flights 54 of the main
conveyor 24 in small discrete amounts 102. The spacing between the
flights and the speed of the main conveyor are selected to let each discrete
amount 102 pass through the screen group before a next amount is fed
down. Similarly, the spacing between the flights 54 and the speed of the
conveyor belt 50 are selected to ensure that each discrete amount is fed
through the air delivery system 42 in an intermittent feed manner. This
feature has been found to be advantageous for preventing clogging of the
feeder.
It is believed that the intervals between the discrete amounts 102
contribute to letting the feed waste flow through the screens 58, 60 without
clogging the screens. It is believed that this features, basically, provides
the
screens with a self cleaning effect. Similarly, it is believed that the
intermittent feed of pellets through the air delivery system 42 provides this
air delivery system with the ability to clean itself after each blown measure
102. It is believed that this intermittent feed feature contributes greatly to
the free-flowing or low-clogging properties of the feeder according to the
preferred embodiment.
In that regard, an efficient operation of the feeder has been obtained
with a flight spacing of about 8 inches, a flight width of about 12 inches
and flight height of about 1 inch. The speed of the belt was selected to
provide a feed material delivery rate of up to 110 lbs. per minute. In this
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installation, the capacity of the blower 34 was selected to provide a pellet
throwing distance of about 60 to 70 feet.
Referring now to FIGS. 5 to 8, the air delivery system 42 will be
explained in greater details. The accept conveyor 28 has an endless belt
106 driven by a motor 108. Referring particularly to FIG. 7, the venturi
eductor 30 has a cylindrical casing 110, an air supply pipe 112 entering the
cylindrical casing 110 at right angle with the central axis of the casing and
which is connected to the air blower 34 by the hose 36, as previously
explained. The cylindrical casing 110 has a throat opening 116 in one end
thereof from which extends a nozzle or a discharge pipe 32. The venturi
eductor 30 has a suction, or inlet pipe 118 extending along a central axis
thereof opposite the nozzle 32 and into the throat opening 116.
The position of the inlet pipe 118 along the central axis of the
cylindrical casing 110 is adjustable relative to the throat opening 116 to
create more or less suction in the inlet pipe 118 and to increase or decrease
the pellet delivery distance. The position of the inlet pipe 118 relative to
the cylindrical casing 110 is adjustable by sliding it along its length and
clamping it in the first clamp collar 120 affixed to the end of the
cylindrical
casing 110. The position of the cylindrical casing 110 is also adjustable
relative to the position of the accept conveyor 28 by means of a second
clamp collar 122 enclosing the circumference of the cylindrical casing 110.
The second clamp collar 122 is affixed to a pair of support arms 124
extending rearward from the collar 122 relative to the nozzle 32. The
support arms 124 are pivoted to two support braces 126 on the articulated
support assembly 40. The attachment of the arms 124 to the support
braces 126 consists of a pair of pivots 130 jointly defining a horizontal axis
132. The venturi eductor 30 and the nozzle 32 are movable about this
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horizontal axis 132 by means of a first linear actuator 134 affixed to one of
the arms 124 and to one of the support braces 126.
The support braces 126 extend downward from a turn table 136
which is movable about a vertical axis 138 by means of a second linear
actuator 140 affixed to the turn table 136 and to a bracket 142 mounted to
the frame 56 ofthe feeder. Due to this arrangement, the venturi eductor 30
and the nozzle 32 are movable from side to side and up and down to
dispense feed pellets over a wide area of a fish pen.
It will be appreciated that during a movement of the venturi eductor
30, the inlet pipe 118 moves as well. For this reason, the inlet pipe 118 has
a D-shaped mouth opening 150 in which the straight edge 152 lies near or
lightly touches the surface of the belt 106 of the accept conveyor 28, over
the downstream end of the accept conveyor. The straight edge 152 is
contiguous with the horizontal axis 132 and has a mid-point intersected by
the vertical axis 138. This arrangement causes the straight edge 152 of the
inlet pipe 118 to remain near the belt 106 and centred with the belt when
the nozzle 32 is moved from side to side and up and down.
The turn table 136 is mounted to a bracket 154 which is adjustably
mounted to a support plate 156 affixed to the frame 56 of the feeder 20.
The bracket 154 is adjustable in up or down positions relative to the
support plate 156 by means of a set screw 158 and clamping bolts or
otherwise. It will be appreciated that the provision of the set screw 158 is
advantageous for adjusting a gap between the straight edge 152 on the inlet
pipe 118 and the surface of the belt 106.
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In order to further increase the efficiency of the feeder, there is
provided a pair of flexible blades 160 enclosing the mouth opening 150 of
the inlet pipe 118. The blades 160 are mounted to the tabs 162 on the sides
of the accept conveyor 28, and each blade has a free end extending
alongside the mouth opening 150 of the inlet pipe 118. There is provided
a semi-circular band 164 over the top portion of the inlet pipe 118, near the
mouth opening 150. This band 164 extends down along both sides of the
mouth opening 150 and encloses loosely the flexible blades 160 to loosely
retain the flexible blades 160 against the mouth opening 150. During
l0 movement of the inlet pipe 118 relative to the accept conveyor 28, the
flexible blades 160 deflect the feed pellets into the mouth opening 150 of
the inlet pipe 118 in order to maintain the efficiency of the feeder 20
regardless of the orientation of the nozzle 32.
As to other manner of usage and operation details of the present
invention, the same should be apparent from the above description and
accompanying drawings, and accordingly, further discussion relative to the
manner of usage and operation details would be considered repetitious and
is not provided.
While one embodiment of the present invention has been described
hereinabove, it will be appreciated by those skilled in the art that various
modifications, alternate constructions and equivalents may be employed
without departing from the true spirit and scope of the invention.
Therefore, the above description and the illustrations should not be
construed as limiting the scope of the invention which is defined by the
appended claims.
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