Threshing of harvested grain

Details Threshing of harvested grain Threshing of harvested grain

1998-08-18

2001-01-23

Pezzuto, Robert E. (Department: 3671)

Crop threshing or separating

Corn processing apparatus

With shelling

C460S046000, C460S099000, C460S143000

Reexamination Certificate

active

06176778

ABSTRACT:

FIELD OF THE INVENTION
THIS INVENTION relates to the threshing of harvested grain. It relates more specifically to a method of threshing harvested grain and to harvesting apparatus.
It is envisaged that the invention will find application in the field of threshing of grain like maize (corn), wheat, beans, and the like, more particularly in the field of harvesting grain having lightweight or small, or both lightweight and small grain kernels such as wheat.
For purposes of this specification, the term “threshing” (and derivatives thereof) should be interpreted as including threshing, separating and cleaning (and corresponding derivatives thereof).
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, there is provided a method of threshing harvested grain in the form of ears, pods, and the like, the method including
performing a threshing action on the harvested grain in a threshing zone which is bounded, at least along a lower extremity thereof, by a sieve, causing an air flow stream of predetermined force or intensity to move through the threshing zone, perforations of the sieve being selected to pass grain liberated during threshing with little clearance, the force or intensity of the air flow stream being predetermined generally such as to carry chaff (of relatively low density) out of the threshing zone and to allow liberated grain (of relatively high density) to fall onto the sieve;
gathering grain and smaller portions of chaff passed by the sieve in a trough spaced underneath the sieve;
causing an auxiliary air flow stream of predetermined force or intensity to move through a space intermediate the sieve and the trough to carry such smaller portions of chaff out of said space while allowing the grain to fall into the trough;
providing a main grain exit for the trough toward an end of the trough which is an upstream end relative to said auxiliary air flow stream and causing a major portion of the grain to move toward and to exit via said main grain exit;
providing an auxiliary grain exit through the trough toward an end thereof which is a downstream end relative to said auxiliary air flow stream to allow the grain remaining in the trough and any remaining chaff to pass through the auxiliary grain exit.
For economy of writing, for purposes of this specification, terms denoting direction or relative position such as “upstream” and “downstream” must be interpreted in relation to the direction of flow of the auxiliary air flow stream.
Advantageously, the method may include barring a portion of the space intermediate the sieve and the trough, at a longitudinal position closely downstream of the auxiliary grain exit, by means of a transverse end baffle extending from a bottom of the trough.
By way of development, even more advantageously, the method may include barring a portion of the space intermediate the sieve and the trough also at a longitudinal position opposite the auxiliary grain exit and upstream of said transverse end baffle by means of a transverse intermediate baffle extending from the sieve, to cause the auxiliary air flow stream to follow a circuitous route past the intermediate and end baffles. In such a circuitous air flow stream, the lighter particles, i.e. the chaff, will be influenced largely by the effect of the air flow stream and will tend to follow the air flow stream. In contrast, the heavier particles, i.e. the grain, will be influenced less by the air flow stream because of their higher inertia and will tend to follow tangential paths. Thus, by creating the circuitous route by means of the baffles, the grain will tend to be directed toward and into the auxiliary grain exit to a larger extent than the chaff.
A preferred method may include arranging the threshing zone and the trough generally parallel at an inclined attitude such that the directions of flow of the air flow stream and the auxiliary air flow stream are obliquely upwardly. The inclined attitude may be at least about 20°, preferably at least about 30°, most preferably about 45°. The invention is, however, not limited to the inclined attitude, and a horizontal and even vertical arrangement fall within the scope of this invention.
The method may include recirculating the grain and any chaff from the auxiliary grain exit to the threshing zone.
Instead, the method may include
passing the grain and any chaff from the auxiliary grain exit to a cleaning zone which is bounded at least along a lower extremity thereof by a sieve, the auxiliary grain exit being directed at said sieve;
agitating or stirring said grain and chaff; and
causing a cleaning air flow stream of predetermined force or intensity to move through the cleaning zone, perforations of the sieve being selected to pass cleaned grain with little clearance, the force or intensity of the cleaning air flow stream being predetermined generally such as to carry chaff (of relative low density) out of the cleaning zone and to allow cleaned grain (of relatively high density) to fall onto the sieve.
In addition, the method may include transporting grain (conveniently under gravity) from the main grain exit to an inlet of the cleaning zone at a longitudinal position spaced upstream, in relation to the cleaning air flow stream, of the auxiliary grain exit, subjecting said grain from the main grain exit to the cleaning air flow stream to carry any chaff off and to allow grain to pass through the sieve. It is contemplated that, generally, all of the grain from the main grain exit will pass through the sieve before a longitudinal position, where grain from the auxiliary grain exit enters the cleaning zone, is reached. Thus, it is contemplated that grain from the respective exits will not mix in a zone above the sieve in the cleaning zone.
In other methods, cleaning may be effected conventionally, e.g. in a shaker sieve or reciprocating sieve cleaning apparatus.
In accordance with a second aspect of this invention, there is provided threshing apparatus suitable for use in threshing harvested grain in the form of ears, pods, or the like, the threshing apparatus comprising
a casing defining a threshing zone and including a sieve bounding at least a lower extremity of the threshing zone;
transport means arranged to transport the harvested grain into the threshing zone;
threshing means arranged to thresh the harvested grain in the threshing zone;
air flow stream generating means arranged to move air in an air flow stream through the threshing zone;
a trough spaced underneath the sieve;
auxiliary air flow generating means arranged to move air in an auxiliary air flow stream through the space intermediate the sieve and the trough;
a main grain exit toward an end of the trough which is an upstream end in relation to the auxiliary air flow stream and an auxiliary grain exit therethrough toward a downstream end of the trough,
the arrangement being such that grain, liberated during threshing, falls onto the sieve, perforations of the sieve being selected to pass such liberated grain with little clearance, such that chaff is carried in the air flow stream out of the threshing zone, such that grain and smaller portions of chaff passed by the sieve fall toward the trough to be exposed to the auxiliary air flow stream, the smaller portions of chaff being carried out of the space on the auxiliary air flow stream, such that a major portion of the grain exit the space via the main grain exit, and such that the balance of the grain, and any chaff remaining in the grain, exit the space via the auxiliary grain exit.
Advantageously, the threshing zone may be generally round cylindrical, having a threshing axis which is inclined at an angle of at least 20° (preferably at least 30°, most preferably about 45°) from the horizontal, the sieve being correspondingly cylindrically arcuate or convex and being arranged generally concentrically of the threshing axis, the trough being arranged generally parallel to and underneath the sieve.
By way of development, the threshing apparatus may include a transverse end baffle extending upwardly from the trough parti

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