Abstract:
An apparatus for dehulling grass seed utilizing a vibrated housing having an elongated chamber. The interior of the chamber is accessible through openings or ports that provide a plurality of entries and exits for the processing of grass seed. Grass seed is dehulled by a housing mounted pneumatic accelerator that removes the hulls from the seeds. Hulls and seeds are then directed into the interior of the chamber wherein separation of seeds from hulls and hulls containing seeds occurs. Seeds are discharged from the chamber and the hulls containing seeds are returned to the pneumatic accelerator for repeating the dehulling process.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the separation of grass seeds having different mass and trajectory paths through space, and particularly to dehulling grass seed, then separating the grass seeds from their hulls and more particularly, to the dehulling and separation of hubs from buffelgrass seed. 
     BACKGROUND OF THE INVENTION 
     Various types of grasses, as web as grain crops, are grown primarily for seeds, and the value of such seed crops is determined by the purity and germination factor of the harvested seeds. The known methods and apparatus for dehulling seeds, or the like, usually consist of submitting the seeds to some type of mechanical or pneumatic effort to break the hubs and then separate the seeds from the hulls. 
     One such method to separate seeds from hubs is disclosed in U.S. Pat. No. 4,335,151 to Caubet. Caubet discloses a method of separating seeds from hubs by feeding hulls containing seeds, into a turbulent flow of compressed air in a flow passage of sufficient size to accelerate the hulls containing seeds to a high velocity. The flow of compressed air and hubs containing seeds are than fed into a second passage of much larger cross-sectional area then the first passage. This sudden change of volume greatly expands the air density causing mechanical stresses to be exerted onto the hulls of the seeds thereby cracking the grass seed hubs and allowing the seeds to be separated from the hull. 
     Mechanical method of dehulling becomes ineffective when the force required to remove the seed from the hub also destroys the seed due to mechanical abrasion and high impact with other seeds and hulls. 
     U.S. Pat. No. 4,933,072 to Beisel discloses a technique of horizontally projecting a flow mixture of seed, hubs, and hulls containing seeds utilizing pressurized air to propel the flow mixture through a venturi nozzle and coanda curve combination into a classification chamber. That technique proves to be ineffective when the hulls comprise the substantial weight of the hull and seed combination. 
     U.S. Pat. No. 4,505,196 to Beisel discloses a seed dehuller that has a momentum type separator that is capable of batch dehulling and separating seeds from hulls. That type of separator will periodically expose seeds to high air pressure and then to a period of substantially reduced air pressure to effect the dehulling of the grass seeds. During the period of reduced air pressure the heavier seeds will be separated from the hulls by their greater momentum and directed into a collection bin. That particular type of separator disclosed by Beisel prove ineffective when the grass seed or grains to be dehulled have extremely hard shells such as buffelgrass seed. 
     Buffelgrass seed is a very hearty and fast growing type of grass. However, buffelgrass seed has a tender seed and a very hard hull that impedes germination of the seed once the seed is planted in the earth. Comparative test results have established that if the hull is removed from buffelgrass seed before planting, an approximate 20-fold increase in germination of the planted seed can be expected. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward the removing of a hull from around a tender seed wherein the seed comprises the substantial portion of the weight of the seed and hull combination. The removal of the seed from its huh is accomplished by friction and grinding action between hulls and hulls containing seeds. This type of dehulling provides less damage to the tender grass seeds, hence greater germination of the seeds. These seeds are then separated from the hulls and any other debris or hull fragments that may occur due to processing by the present invention. The seeds are then ready for shipment to growers of grasses, grains, or the like. 
     The preferred embodiment of the present invention utilizes a substantially-rectangular, inclined, and continuous vibrated housing having an elongated chamber. This chamber is defined by a bottom wall, a forward sidewall, a rear side wall, two parallel longitudinal side walls, and a top wall detachably enclosing the chamber. The interior of the chamber is accessible through opening or ports in the walls of the chamber, thereby providing means for entry of hulled seed, exit of dehulled seeds, exit of hulls and an exit of hulls containing seeds. 
     The present invention has disposed within the housing a platform parallel to and spaced from the bottom wall of the housing to provide the means for separating hulls from dehulled seeds and hulls containing seeds. The platform has a length wise adjustable upright barrier adjacent to one end of the platform, whereby seeds and hulls containing seeds only will traverse the platform barrier combination and descend to the bottom of the housing beyond the barrier. Hulls and hull fragments will impact the platform and barrier surface and be urged toward the hull exit by oscillation and/or vibration of the chamber thereby separating grass seed and hulls containing grass seed from hulls. The bottom of the housing has a screen covering the dehulled seed exit. This screen, which vibrates with the housing, is sized to separate seeds from hulls containing seeds. The seeds will pass through the screen openings and exit the housing throughout the dehulled seed exit port. The hulls containing seeds will traverse the screen and exit the housing through the hulls containing seeds exit port. 
     All hulls containing seeds are processed through a dehulling pneumatic accelerator housing, defined by a first venturi nozzle that has an axial passage with a discharge opening disposed within the upper portion of one end of the housing. The first venturi nozzle has a first inlet coaxially aligned with the axial passage. This inlet has connected thereto a source for supplying a flow of pressurized air. 
     The first venturi nozzle has a second inlet angularly intersecting the axial passage, proximal to the first inlet. The second inlet has a connecting flow passage to the hulls containing seeds exit port, thereby providing a means for receiving and transporting hulls containing seeds from the housing to the pneumatic accelerator. Within the pneumatic accelerator, the pressurized air flow traverses the second inlet creating a suction flow of hulls and hulls containing seeds. This flow mixture proceeds through the second inlet whereby all hulls and hull containing seeds are traveling at various velocities, causing air turbulence and dehulling by the collision of hulls containing seeds, in the proximity of the first venturi&#39;s second inlet. 
     The pneumatic accelerator is further defined by a second nozzle adjacent and parallel to the discharge end of the first venturi nozzle, the second nozzle defining an axial passage. This axial passage has a discharge opening at one end, parallel and contiguous to the first venturi nozzle&#39;s discharge opening, whereby both nozzles have their respective discharge openings communicating with the upper portion of one end of the housing. The other end of the second nozzle is contoured to form an inlet opening, that is aligned with its axial passage that will freely communicate with ambient air. The pneumatic accelerator additionally has an integral lower housing defined by a downwardly directed coanda curving member. This curving member is directed towards the hull exit in the lower portion of the housing whereby a substantial portion of the air stream traversing that curving member has been separated from the seeds, hulls, and hulls containing seeds by the coanda effect of the curving member. 
     Seeds, hulls, and hulls containing seeds will be directed from the pneumatic accelerator into the upper portion of the housing by their momentums. Seed and hulls containing seeds have a greater momentum then hulls alone because of their relative mass differentials, therefore, most hulls will impact the platform and exit the housing through the hull exit port, and the seeds and hulls containing seeds will traverse the platform to be respectively separated and reprocessed. This process of dehulling, separating hulls from seeds and hulls containing seeds and separating seeds from hulls containing seeds, continues until all seeds are dehulled and separated from their hulls. 
     Further advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description, taken in conjunction with the annexed sheets of drawings on which is shown, a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a grass seed dehulling machine. 
     FIG. 2 is an end view of FIG. 1. 
     FIG. 3 is a side elevation view of FIG. 1. 
     FIG. 4 is a perspective end view of FIG. 2. 
     FIG. 5 is a perspective view of a pneumatic accelerator. 
     FIG. 6 is a sectional view of FIG. 5 at 6--6. 
     FIG. 7 is a cross-sectional view of a FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 generally shows an apparatus 10 for dehulling and separating grass seed. The apparatus comprises a substantially rectangular housing 12 having an elongated chamber 12a (FIG. 3). This chamber is defined by a bottom wall 12b, a forward side wall. 12c, a rear side wall 12d, two parallel longitudinal side walls 12e and 12f, and a top wall 12g, detachably enclosing chamber 12a. Housing 12 is mounted to table 14, having a selectably inclined frame 14e, by springs 14a, 14b, 14c, and a fourth spring (not shown). 
     The inclined angle of frame 14e is selected by positionally adjusting apparatus 14f along its substantially vertical axis. Table 14 and frame 14e are sized to support the weight of housing 12 and a full compliment of grass seed. A motor 16 is provided that may, if desired, be mounted adjacent to sidewall 12e or 12f of housing 12. Motor 16 provides a means to continuously vibrate the housing by the attached cam 16a that imparts a vibratory action to housing 12. 
     Housing 12 has a first entry port 12h disposed in top wall 12g in proximity to forward wall 12c for entry of hulled grass seed. A second entry port 12i is disposed in the rear wall 12d in proximity to the top wall 12g for entry of dehulled seeds, hulls containing seeds, and hulls. Housing 12 also has a first exit port 12j disposed in the bottom wall 12b for discharging seeds, a second exit port 12k for the exit of hulls, and a third exit port 12 for hulls containing seeds. Exit ports 12k and 12l are disposed in the lower portion of the rear wall 12d as illustrated in FIG. 4. 
     The interior of housing 12c has a means for separating hulls from dehulled seeds and hulls containing seeds. This means is defined by a platform 12m having one end lengthwise adjustable by an extension member 12n, whereby only seeds and hulls containing seeds due to their greater momentum will traverse members 12m and 12n and descend to the bottom of housing 12. 
     The bottom of housing 12 has a screen 12o covering exit 12j. Screen 12o has openings sized to separate seeds from hulls containing seeds whereby hulls containing seeds traverse screen 12o and exit housing 12 through exit port 12l and dehulled seeds pass through the openings of screen 12o and are discharged from housing 12 through seed exit port 12j. 
     A pneumatic accelerator 18 mounted on the upper portion of rear wall 12d of apparatus 10, is generally shown on FIG. 4. Accelerator 18 provides the means for removing seeds from their hulls. This means is defined by a first venturi nozzle 18a (FIG. 6) having an axial passage 18b. Axial passage 18b has a discharge opening 18c that is disposed within the upper portion of rear wall 12d. The first venturi nozzle has an axial flow barrier 18n traversing axial passage 18b proximal to the first inlet 18d. Barrier 18n has a plurality of axially parallel perforations 18p for producing a laminar flow of air in axial passage 18b. Accelerator 18 also has a conventional compressor (not shown) for supplying pressurized air flow to first inlet 18d. 
     A second inlet 18f angularly intersects the axial passage 18b proximal to first inlet 18d. Inlet 18f has joined thereto a tube 18g providing a conduit for hulls containing seeds from exit 12l to second inlet 18f, whereby the pressurized air flow 18e traversing the second inlet 18f creates a suction flow mixture of hulls and hulls containing seeds that will traverse second inlet 18f. Those mixture components are all traveling at various velocities, causing air turbulence and dehulling by the collisions of hulls containing seeds with other hulls in the proximity to first venturi 18a and spaced from second inlet 18f. 
     Referring to FIG. 6, accelerator 18&#39;s first nozzle 18a is defined by a first cylindrical tube 18o having one end comprising a first air flow inlet 18d. The other end of tube converges to a substantially rectangular shape as shown on FIG. 7. A second substantially rectangular tube 18h is disposed adjacent to the first tube 18o and has one open end 18i, communicating freely with ambient air. The other end of second tube 18h is expanded, thereby defining a second nozzle 18j disposed parallel to and integral with the first venturi nozzle 18a. Accelerator 18 has a substantially rectangular tubular like conduit or housing 18k having one end integral with rectangular tube 18h and first tube 18o as shown in FIG. 6. Housing 18k is in air flow communication with first venturi nozzle 18a. Housing 18k traverses the second entry port 12i, wherein the sidewalls of housing 18k contact and curve downwardly (FIG. 6), defining a downwardly coanda curving member 18L. Curving member 18L converges to a cylindrical shape that is sized to enter the second exit port 12k and terminates therein as shown at 12p whereby the air flow traversing curving member 18L exits housing 12 along exit port 12k, providing a suction effect within the closed housing. That suction effect will aid in the discharge of hulls from housing 12. Housing 18k has a port 18c axially aligned with the first nozzle 18a and second nozzle 18j for receiving and directing the air flow containing seeds, hulls, and hulls containing seeds into housing 12. 
     The best mode of operation for the dehulling and separation of grass seeds by apparatus 10 will now be described. Hulled grass seeds are provided to entry port 12h of housing 12 while housing 12 is vibrated by motor 16 and cam 16a. The hulled grass seeds free, fall to the bottom of chamber 12a, and traverse a screen 12o that is covering seed exit port 12j. The hulled grass seeds proceed along the bottom of chamber 12a to exit port 12. Exit port 12 is connected to the second inlet 18f of accelerator 18 by tube 18g. Pressurized air flow traverses inlet 18f causes a suction flow of hulled seeds into the inlet 18f. That flow mixture containing air and hulled seeds enter into axial passage 18b, whereby separation of the hulls from the seeds occurs due to collision of the hulled seeds with other hulled seeds and the grinding action of empty hulls on hulled seeds. 
     The flow mixture now contains air, hulls containing seeds, hulls, and dehulled seeds all traversing axial passage 18b and towards venturi nozzle 18d. The air pressure within nozzle 18a begins to decrease and the velocity of the flow mixture begins to increase. The flow mixture exits nozzle 18a into tube 18h where a substantial amount of air flow will follow coanda curve 18l and exit housing 12 through the second exit port 12k. The remainder of the flow mixture is directed into the momentum separation chamber 12a through port 18c. Hulls, seeds, and hulls containing seeds will naturally separate due to differences in mass and trajectory. Empty hulls, having the least mass of the mixture, impact platform 12m and are gravity fed to exit port 12k whereby the hulls exit chamber 12a. 
     The mass of hulls containing seeds and the mass of seeds are very nearly the same, therefore, both will pass over platform 12m and free fall toward the bottom of chamber 12a. The resulting location on the bottom of chamber 12a for the hulls containing seeds and seeds is approximately the same as the hulled seeds from port 12h. 
     Platform 12m has a length wise adjustable extension 12n that provides a control mechanism to select the quantity of hulls that will be mixed with seeds and hulls containing seed that traverse platform 12m. 
     The actual position of adjusting member 12n is dependent on various atmospheric conditions, such as humidity and barometric pressure. Also, the moisture content of the grass seed will effect the relative position of adjusting member 12n. The final position of adjusting member 12n is determined by empirical means, e.g., given the above variables adjusting member 12n is adjusted to provide the most seeds exiting port 12j. 
     Seeds and hulls containing seeds that have traversed platform 12m and adjusting member 12n are gravity fed to an area ahead of screen 12o covering seed exit 12j. The vibration of housing 12 by motor and cam 16a will move seeds and hulls containing seeds across screen 12o. Screen 12o is sized to permit the seeds to pass through the screen openings and descend to exit port 12j. Hulls containing seeds proceed along the bottom of chamber 12a to exit port 12L. Port 12L is connected to accelerator 18 by tube 18g, whereby the process of dehulling continues until all hulls are removed from the grass seeds. 
     The invention now being fully described, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.