Abstract:
In a feeder for dispensing moist feed pellets to fish in a fish farm, there are provided a feed storage hopper, a screen group for separating fish feed 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 comprising a venturi eductor and a nozzle 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.

Description:
FIELD OF THE INVENTION  
         [0001]    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  
         [0002]    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.  
           [0003]    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.  
           [0004]    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 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.  
           [0005]    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.  
           [0006]    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:  
           [0007]    U.S. Pat. No. 4,832,538 issued on May 23, 1989 to Steve Bullerman et al.;  
           [0008]    U.S. Pat. No. 4,984,536 issued on Jan. 15, 1991 to James W. Powell et al.;  
           [0009]    U.S. Pat. No. 5,076,215 issued on Dec. 31, 1991 to Ning C. Yang, and  
           [0010]    U.S. Pat. No. 5,337,698 issued on Aug. 16, 1994 to Ronald L. Widmyer.  
           [0011]    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.  
           [0012]    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 then available for recycling. This system is described in the following document.  
           [0013]    CA 2,145,338, a patent application published on Sep. 24, 1996.  
           [0014]    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:  
           [0015]    U.S. Pat. No. 848,101 issued on Mar. 26, 1907 to H. S. Hale, and  
           [0016]    U.S. Pat. No. 5,842,303 issued on Dec. 1, 1998 to George Abraham et al.  
           [0017]    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.  
           [0018]    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.  
         SUMMARY OF THE INVENTION  
         [0019]    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.  
           [0020]    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.  
           [0021]    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.  
           [0022]    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.  
           [0023]    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.  
           [0024]    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.  
           [0025]    Other advantages and novel features of the present invention will become apparent from the following detailed description of the preferred embodiment. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    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:  
         [0027]    [0027]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;  
         [0028]    [0028]FIG. 2 is a partial longitudinal cross-section view of the preferred feeder;  
         [0029]    [0029]FIG. 3 is a perspective view of the primary screen and the lump breaker mounted in the screen group of the preferred feeder;  
         [0030]    [0030]FIG. 4 is a partial side view of the reciprocating mechanism used for imparting reciprocating movements in the primary and secondary screens;  
         [0031]    [0031]FIG. 5 is a perspective view of the accept conveyor and the air delivery system;  
         [0032]    [0032]FIG. 6 is a partial top view of the accept conveyor and the air delivery system;  
         [0033]    [0033]FIG. 7 is a partial longitudinal cross-section view of the accept conveyor and the air delivery system, and  
         [0034]    [0034]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  
       [0035]    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.  
         [0036]    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.  
         [0037]    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 .  
         [0038]    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 .  
         [0039]    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.  
         [0040]    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  58  is between about ½ inch and about ⅝ 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 ¼ inch and about ⅜ inch.  
         [0041]    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.  
         [0042]    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 ⅛ 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 .  
         [0043]    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 pellets to unnecessary stresses.  
         [0044]    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 .  
         [0045]    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 50 degrees. The lump breaker grate  90  remains fixed relative to the frame  56  and to the primary screen  58 .  
         [0046]    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 of passing through the primary screen  58 .  
         [0047]    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.  
         [0048]    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 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 .  
         [0049]    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.  
         [0050]    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.  
         [0051]    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 installation, the capacity of the blower  34  was selected to provide a pellet throwing distance of about 60 to 70 feet.  
         [0052]    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 .  
         [0053]    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 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 .  
         [0054]    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  of the 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.  
         [0055]    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.  
         [0056]    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 .  
         [0057]    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 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 .  
         [0058]    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.  
         [0059]    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.