US3756406A

US3756406A - Grain cleaner

Info

Publication number: US3756406A
Application number: US00162572A
Authority: US
Inventors: A Khan
Original assignee: US Department of Agriculture USDA
Current assignee: US Department of Agriculture USDA
Priority date: 1970-07-14
Filing date: 1971-07-14
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04

Abstract

The grain cleaner comprises a pair of rotating concentric, coaxial screens. Grain is delivered to the inner screen which has a mesh large enough to pass the grain and light impurities, such as chaff, but too small to pass large, heavy impurities such as straw. Baffles move the retained straw toward an exit at one end of the inner cyclinder for collection and disposal. A current of air blowing in the space between the two cylinders separates the grain from the chaff and dust and carries the latter to an exit. Baffles in the outer cylinder move the cleaned grain in a direction opposite to the flow of air for discharge and collection.

Description

United States Patent lllllllllll 49 itl Khan Sept. 4, 1973 [54] GRAIN CLEANER 315,523 4/1885 Lynett 209 294 3,394,808 7 1968 Th 209 29] X [75] Inventor: Khan, Mamla PhlhPPmes 1,386,298 81921 wl lgi 209291 x l [73 Assignee: The United States of America as represented by the Secretary of pmfmry f Agriculture Asslstant Exammer-Wrlham Cuchlmskl, Jr. Attorney-Rubin Hoffman et al. [22] Filed: July 14, 1971 y [5 7] ABSTRACT [211 App]. 162572 The grain cleaner comprises a pair of rotating concentric, coaxial screens. Grain is delivered to the inner [30] Foreign Application Priority Data screen which has a mesh large enough to pass the grain July 14, 1970 Philippines H647 and light im uriti s, su h as chaff. but too small t pass large, heavy impurities such as straw. Baffles move the [52] US. Cl 209/291, 209/294, 209/295 retained Straw toward an exit at one end of the inner [51] Int. Cl B07b 1/24 cyclinder for collection and disposal. A current of air [58] Field of Search 209/295, 291, 294, blowing in the space between the two cylinders sepa- 209/245, 299, 284 rates the grain from the chaff and dust and carries the latter to an exit. Baffles in the outer cylinder move the 56 Ref ren e Cit d cleaned grain in a direction opposite to the flow of air UNITED STATES PATENTS fOl' discharge and COIIfiCtlOII.

1,088,117 2/ 1914 Walter 209/245 X 5 Claims, 2 Drawing Figures PAImIEnsEHm SHEET E 0F Z GRAIN CLEANER The invention relates generally to grain cleaning machines and in particular to a grain cleaner wherein a plurality of perforated cylinders rotate together about a longitudinal axis so as to remove straws, chaff and other dirt from the grains by mechanical screening followed by winnowing operation.

Cleaning machines of the class set forth do not satisfactorily separate and clean the chaff and empty kernels from paddy grains. The popular locally made cleaners consists of a paddle type fan mounted on a wooden frame which directs the air blasts against the grain and foreign material falling from a hopper. The light material is blown farther away than the heavy solid grain and a set of baffles help in the separation process. In usual practice the seeds are repeatedly recycled to achieve satisfactory grain and straw separation.

Grain cleaners popular in industrialized countries clean the grain in two stages. First the grain passes through a set of oscillating screens to remove the larger impurities. Second the grain falls through a high velocity air blast to remove the lighter impurities.

The above type of grain cleaners has two disadvantages. Oscillating screens are often a source of mechanical problems and do not perform well when excessive amounts of straw and other large impurities are present with the grains.

The second disadvantage is that the very short duration exposure of the grain to the air blast does not satisfactorily separate the unfilled immature kernels.

To overcome the abovementioned disadvantages, a novel grain cleaner is provided. The grain cleaner according to this invention uses two rotating concentric cylindrical screens with a suitable clearance between them. The inner screen has perforations that permit passing of grains, chaft and dust whereas the outer screen has perforations small enough to permit the passing only of dust and other finer impurities. Air is blown through the clearance along the portion wherein the grains are tumbled. The grain to be cleaned is delivered into the inner cylindrical screen. The grains fall through the inner screen perforations into the outer cylinder while baffles mounted on the inside of the inner cylinder move the straw and larger impurities axially towards the straw outlet. The grain is tumbled inside the outer cylinder and is moved axially in the direction opposite to the air movement by spiral baffles. The air blows the empty grain and other light impurities from the tumbling grain while it is moving in the outer cylinder toward the elevator for delivery into a container.

It is an object of the invention to provide a perforated cylinder fitted concentrically into a larger cylinder and a means to blow air through the concentric space between the two cylinders.

Another object is to provide a cleaner having the rotating cylindrical screen with perforation larger than the grain but smaller than the large impurities and with a spiral baffle such that when the dirty grain is delivered into the cylinder, the grain falls through the perforations and the larger impurities are retained and moved axially by the spiral baffles to the impurities outlet.

Another object is to provide a cleaner having the second larger cylinder fitted concentrically around the first perforated cylinder to collect the grains and smaller impurities falling from the first cylinder and said second cylinder having perforation smaller than the grain to remove the small impurities and retain the grain.

Another object is to provide means to blow air through the concentric space between the two cylinder to blow the light impurities from the grain falling from the first cylinder.

Another object is to provide means inside the outer cylinder to tumble the grain in the air stream and to move the grain axially towards the grain outlet.

While some of the more salient features, characteristics and advantages of the instant invention have been above pointed out, others will become apparent from the following disclosure taken in connection with the accompanying drawing in which:

FIG. l is a perspective view of the GRAIN CLEANER FIG. 2 is a schematic drawing of said GRAIN CLEANER Referring specifically to the drawings 10 denotes a hopper in which the material to be cleaned is supplied. The hopper it) of the cleaner has a large central opening at the bottom thereof which is located substantially along the longitudinal axis but contiguous to the side wall 11 of the cleaner, the wall 11 also forming one side of hopper 10. The hopper may be supplied with material to be cleaned through the open top thereof manually, mechanically or pneumatically, the particular method of filling the hopper not being involved in the present invention. From the hopper 10 it is intended that the grain be transferred into the inside cylinder. While any suitable means such as gravity, pneumatic or mechanical feeder for this purpose may be employed, it is preferable to use the screw conveyor device 12 shown in FIG. 2.

The hopper sidewalls 13 & 14 are inwardly inclined and largely cut and formed to merge with auger housing 15. The auger housing 15 is a partly open tube which extends into the inner cylinder as shown at 39. The tube may be maintained in position by riveting to the hopper bottom or equivalently secured thereto by a number of suitable brace rods. Inside housing 15 is an auger comprising shaft 17 with serpentine or helical spiral 22 therearound. The drive end of shaft 17 extends through a suitable bearings lb and the projecting portion of the shaft is connected to a suitable pulley 19 which establishes a drive for the auger and is in turn driven by the prime mover 20. However any suitable drive connection from the prime mover 20 to the auger shaft 17 may be employed aside from the belt and pulley assembly herein preferably provided.

The grain cleaner has two rotating cylinders. The inner perforate cylinder 21 is of smaller diameter and is surrounded by a perforate or non-perforated outer cylinder 23. The inner cylinder 2k is held at accurate concentric distance by spacer 24 to define a clearance with the surrounding cylinder 23 throughout its length. The inner and outer cylinder assembly is supported by the shaft 29 mounted on suitable bearings with radial arms 25. The assembly could be alternately supported on external rollers that may be provided along the bottom portions of cylinder 23. As noted in FIG. 2 the major portion of the inside cylinder 21 is occupied by a spiral baffle member 26 wound to form an internal auger. The spiral member 26 extends from the region of the auger housing If to a part at the outer end of said inner cylinder 21. When the drum is caused to rotate in the direction of the arrow in FIG. 2 and a supply of unclean grain is fed by the auger 12 into the inner rotating cylinder 21, the material first starts to tumble in the region marked A. However as the cylinder rotates, the material moves axially and the grains gradually falls through the perforate walls 45 of the inner cylinder 21 and the straws and large impurities continue to move outwardly along the convolutions of the spiral member 26.

Concentric with the inner cylinder as shown in H6. 2 there is illustrated an outer cylindrical shell 23 having belt 27 thereon by which the shell 23 may be suitably rotated. Conventional supporting means are shown diagramatically at 29 and a rotating means 28 & 31, the latter being driven from a suitable prime mover such as a gasoline engine with speed reducing equipment generally indicated at 30. The outer cylindrical shell 23 may be constructed as perforate or imperforate metallic shell or made of fine mesh screen material. The size of the apertures 52 or perforations in the outer cylindrical shell are such that the apertures are smaller than the size of the grain being cleaned.

As will be seen from the foregoing, the problem in machines of the character particularly hereinabove set forth is to clean the grains of small or fine dirt after it has been initially cleaned of straws and large dirts. This is especially true when the material to be cleaned is wet because dirt and chaff cling closely to the grain. For this purpose there is provided in accordance with the present invention a plurality of projections 32 which are disposed parallel to the axis of the cylindrical shell 23. The series of planiform ribs 32 are arranged to extend along the length of the cylindrical shell and at convenient intervals after which their continuity is interrupted by a series of spirally disposed slide fins 33.

The series of ribs 32 exert a maximum tendency to lift the grains and dirt and to drop such material into the air passing through the annular space. This turning and tumbling of the grains and dirt in the stream of air inside the annular space effectively cleans the grain of chaff and dirt. As the grain in tumbled, the spirally disposed fins 33 continue to intermittently move the grain against the air stream and to discharge said grains into a semi-circular trough 36 wherein it is swept by the elevator flap sweeper into

discharge outlets

37 and 38.

Any suitable means could be provided to deliver a draft of air to clean the grain and also to drive the auger shaft and the cylindrical shells. Such means are somewhat diagramatically illustrated in the drawing and comprise an internal combustion engine mounted on a side frame 40 which through its shaft 41 and a suitable belt and pulley connection 42 or the equivalent, drives the blower fan 43 which discharges air into the clearance between the inner and outer cylinders through conduit 44.

Blower 43 supplies air in a direction as indicated by the arrows 48. The lighter material that has been delivered into the outer screen and such as dust, chaff and straw particles is blown off the cylinder indicated at 49. Small impurities not carried by the air, fall through the outer screen onto the ground as indicated at 51.

While a preferred embodiment of the invention has been described above, it will be understood that this embodiment is illustrative only and the invention is to be limited solely by the appended claims.

I claim:

1. A grain cleaning machine comprising an inner cylinder adapted for rotation about a longitudinal axis, said inner cylinder having openings therethrough closely spaced from each other substantially throughout its area, said opening being of such size as to pass the kernels of grain, dirt and smaller-than-grain impurities and to retain straws and larger-than-grain impurities; an outer cylinder surrounding said inner cylinder; the outer periphery of said inner cylinder and the inner periphery of said outer cylinder defining an annular space; means providing grain inlet into said inner cylinder; means to provide air inlet into said annular space; means to tumble the grain in said annular space; means providing a grain outlet on said outer cylinder; guide means in said outer cylinder to advance grains toward said outlet and drive means to operate said cylinders and said means providing air inlet into said annular space.

2. A grain cleaning machine as in claim 1 wherein the inner cylinder has a plurality of spiral baffles inside said inner cylinder to form an internal auger to advance straws and larger-than-grain impurities towards an outlet.

3. A grain cleaning machine as in claim 2 wherein the outer cylinder openings therethrough closely spaced from each other substantially throughout its area, said openings being of such size as to pass dirt, sand and smaller-than-grain impurities and to retain kernels of grains.

4. A grain cleaning machine as in claim 3 wherein the outer cylinder has a plurality of projections, said projections being constructed and arranged to provide turning and tumbling of grains upon rotation of said outer cylinder.

5. A grain cleaning machine as in claim 4 wherein the guide means in the outer cylinder comprise a plurality of slide fins disposed spirally inside the outer cylinder to move the grain towards the grain outlet in axial direction counter to the flow of air in said annular space as the grains come into engagement with said slide fins when said outer cylinder is rotated.

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