FIELD OF THE INVENTION
The present invention generally relates to agricultural harvesters. More
particularly, the present invention relates to threshing and separating systems
for agricultural harvesters and a method of threshing and separating crop
5 material by using such threshing and separating systems.
BACKGROUND OF THE INVENTION
An agricultural harvester also termed as a combine harvester, or simply combine,
is a machine for harvesting a variety of crops. The term ‘combine’ means it
combines multiple harvesting functions with a single harvesting unit, such as
10 gathering, threshing, separating and cleaning. A combine includes a header
which gathers the crop from a field, and a conveyer which transports the crop
into a threshing rotor. The threshing rotor rotates within a perforated housing,
which may be in the form of adjustable concaves and performs a threshing
operation on the crop to remove the grain. Once the grain is threshed it falls
15 through perforations in the concaves onto a grain collecting tank. A cleaning fan
blows air through the sieves to discharge chaff and other debris toward the rear
of the combine. When the grain tank becomes full, the combine is positioned
adjacent a vehicle into which the grain is to be unloaded, such as a tractor with a
trailer or the like; and an unloading system on the combine is actuated to
20 transfer the grain into the trailer.
More particularly, a rotary threshing and separating system includes one or more
rotors which can extend axially (front to rear) or transversely within the body of
the combine, and which are partially or fully surrounded by a perforated
concave. The crop material is threshed and separated by the rotation of the rotor
25 within the concave and the non‐grain crop material such as stalks and leaves are
transported to the rear of the combine and discharged back to the field. The
separated grains are discharged through the concaves and fall onto a grain
3
collecting tank. As the rotor rotates, crop material is carried across the surface of
the rotor. To move the crop material across a length of the rotor during rotation,
multiple rasp bars are connected to the surface of the rotor and arranged in a
spiral pattern to direct the crop material down the length of the rotor. The rasp
5 bars each define a fixed angle of inclination relative to the tangent of the outer
surface of the rotor, with certain configurations of the rasp bars being optimal
for different types of crops and harvesting conditions.
When a different configuration of the rasp bars is desired to, for example,
account for differing harvesting conditions such as changing crop types, crop
10 moisture, through put, grain real time quality and grain damage, the rasp bars
must be replaced by a new set of rasp bars or the entire rotor must be replaced
because the rasp bars are not adjustable in terms of angle of inclination or
orientation or position. The rasp bars are fixed with the rotor by bolt or welding
and they will get replaced when they are worn out, i.e. the rasp bars are not
15 adjustable.
Accordingly, as the rasp bars are fixed, they will not efficiently cope up with the
changing crop types, crop moisture, through put, grain real time quality and
grain damage. For all types of crops and moisture, the position of rasp bars is
same, and every time concaves’ position needs to be adjusted to maintain the
20 gap in between rasp bars and concaves. Further, there is wear in the rasp bars’
aggressive surfaces because of their same position irrespective of the crop size,
resulting in non‐uniform pressure and friction occurring at aggressive surfaces of
the rasp bars. Therefore, the quality of grain is not good enough (damaged
grains) due to worn out rasp bar parts. Further, wear in rasp bars will result in
25 lower quality of threshing as the threshing happens due to the compression of
crop in between rasp bars’ aggressive surface and concaves. Therefore, manual
changing of worn out rasp bars is required from time to time for achieving good
threshing effect. In this scenario, the cost to the user in terms of both time and
4
resources can be extremely high since the user must stop harvesting to replace
the configuration of the rasp bars with an entirely separate set of rasp bars or
rotor.
Therefore, there is a need for an improved threshing and separating system
5 which can overcome some of the disadvantages of known systems by manually/
automatically manipulating the rasp bar orientation, position and inclination to
achieve better threshing efficiency while the combine is operating.
OBJECT OF THE INVENTION
It is therefore an object of the present invention to provide an agricultural
10 harvester comprising a threshing and separating system that includes an
adjustable rasp bar of which the inclination, orientation and position can be
manipulated manually/ automatically to achieve better threshing efficiency,
better grain quality and minimize grain damage.
It is a further object of the present invention to prevent the wear out of the rasp
15 bars by providing fresh aggressive surfaces for threshing by changing the angle of
inclination of the rasp bars, thereby increasing rasp bars’ life and optimizing the
power required for threshing.
It is another object of the present invention to provide a threshing and
separating system for adjusting the gap between rasp bars and concaves.
20 It is yet another object of the present invention to make the threshing system
more economically beneficial by increasing the durability of rasp bars and thus
saving the cost (material cost, replacement cost).

We claim:
1. An agricultural harvester (100) including a threshing and separating system
(106), the threshing and separating system (106) comprising:
5 at least one threshing rotor (200) having an outer surface (S1) and an inner
surface (S2);
at least one concave (203); and
a plurality of rasp bars (201) attached to the outer surface of the threshing
rotor (200), each rasp bar having an aggressive surface (202) defining a respective
10 angle of inclination (A) relative to a tangent (T) of the outer surface,
wherein,
at least one of the plurality of rasp bars (201) is an adjustable rasp bar (300)
with an adjustable aggressive surface (303), one end (E1) of which is pivotably
coupled to the threshing rotor (200) and a lifting mechanism coupled to the other
15 end (E2) of the adjustable rasp bar (300) is configured to selectively pivot the
adjustable aggressive surface (303) to adjust the respective angle of inclination (A)
of the adjustable rasp bar (300).
2. The agricultural harvester (100) as claimed in claim 1, wherein the adjustable rasp
20 bar (300) is pivotable about a pivoting axis extending in a longitudinal direction (L) of
the threshing rotor (200).
3. The agricultural harvester (100) as claimed in claim 1, wherein the adjustable rasp
bar (300) is pivotably coupled to the threshing rotor (200) by a pin joint (301).
25
4. The agricultural harvester (100) as claimed in claim 1, wherein the angle of
inclination (A) of the adjustable rasp bar (300) is adjustable between 0‐45°.
17
5. The agricultural harvester (100) as claimed in claim 1, wherein the lifting
mechanism is an automatic lifting mechanism (304A1, 304A2).
5 6. The agricultural harvester (100) as claimed in claim 3 and 5, wherein the
automatic lifting mechanism (304A1) comprises:
a first gear (401);
a second gear (402);
a support system (403) having a shaft (404);
10 an actuator (405); and
a support bracket (406),
wherein when a torque is applied by the actuator (405) to the first gear (401)
through the shaft (404), the first gear (401) rotates and transmits power to the
second gear (402) assembled on a threaded bolt (407) fixed on the rasp bar (300),
15 enabling the second gear (402) to rotate around the threaded bolt (407) and to
move the other end of the rasp bar (300) in upward or downward direction about
the pin joint (301) thereby changing the angle of inclination (A) of the rasp bar (300),
and
wherein the downward movement of the other end of the rasp bar (300) is
20 achieved by reversing the direction of rotation of the first and second gears (401,
402) by the actuator (405).
7. The agricultural harvester (100) as claimed in claim 6, wherein the actuator (405)
is a pneumatic actuator.
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8. The agricultural harvester (100) as claimed in claim 6, wherein the actuator (405)
is an electric actuator.
18
9. The agricultural harvester (100) as claimed in claim 6, wherein the support
bracket (406) holds the lifting mechanism (304A1) and the other end of the
adjustable rasp bar (300) and have cutout to compensate the space for the threaded
5 bolt (407) when the other end of the rasp bar (300) moves in upward or downward
direction.
10. The agricultural harvester (100) as claimed in claim 3 and 5, wherein the
automatic lifting mechanism (304A2) comprises a reciprocating actuator (508) one
10 end of which is mounted on the inner surface (S2) of the threshing rotor (200) and
the other end is connected to the rasp bar (300), wherein the stroke of the
reciprocating actuator (508) moves the other end of the rasp bar (300) in upward or
downward direction about the pin joint (301) thereby changing the angle of
inclination (A) of the rasp bar (300).
15
11. The agricultural harvester (100) as claimed in claim 1, wherein the lifting
mechanism is a manual lifting mechanism (304M1, 304M2).
12. The agricultural harvester (100) as claimed in claim 3 and 11, wherein the
20 manual lifting mechanism (304M1) comprises a supporting bracket (601) detachably
connected to the other end of the rasp bar (300) by nuts and bolts (602) through
synchronous holes (H) provided on the supporting bracket (601) and the other end
of the rasp bar (300), wherein the angle of inclination (A) of the rasp bar (300) is
manually changed by lifting the other end of the rasp bar (300) about the pin joint
25 (301) and fixing it in different synchronous holes (H).
19
13. The agricultural harvester (100) as claimed in claim 3 and 11, wherein the
manual lifting mechanism (304M2) comprises a supporting bracket (701) detachably
connected to the other end of the rasp bar (300) by nuts (702) and a threaded bolt
(703), wherein the angle of inclination (A) of the rasp bar (300) is manually changed
5 by tightening and loosening the nuts (702) about the threaded bolt (703), thereby
lifting the other end of the rasp bar (300) about the pin joint (301).
14. A method of threshing and separating crop material (CM) by a threshing and
separating system (106) of an agricultural harvester (100), the threshing and
10 separating system (106) comprising at least one threshing rotor (200) having an
outer surface (S1) and an inner surface (S2), at least one concave (203) and a
plurality of rasp bars (201) attached to the outer surface of the threshing rotor
(200), each rasp bar (201) having an aggressive surface (202) defining a respective
angle of inclination (A) relative to a tangent (T) of the outer surface, wherein at least
15 one of the plurality of rasp bars (201) is an adjustable rasp bar (300) with an
adjustable aggressive surface (303), the method comprising:
selectively pivoting the adjustable aggressive surface (303) of the adjustable
rasp bar (300) to adjust the respective angle of inclination (A) while the agricultural
harvester (100) is operating.
20
15. The method as claimed in claim 14, wherein the angle of inclination (A) is
adjusted automatically by an automatic lifting mechanism (304A1, 304A2).
16. The method as claimed in claim 15, wherein automatically adjusting the angle of
25 inclination by the automatic lifting mechanism (304A1) comprises the steps of:
applying a torque by an actuator (405) to a first gear (401) through a shaft
(404) of a support system (403);
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rotating the first gear (401) and transmitting power to a second gear (402)
assembled on a threaded bolt (407) fixed on the rasp bar (300),
wherein the second gear (402) rotates around the threaded bolt (407),
thereby moving the other end of the rasp bar (300) in upward or downward
5 direction,
wherein the downward movement of the other end of the rasp bar (300) is
achieved by reversing the direction of rotation of first and second gears (401, 402)
by the actuator (405), and
wherein movement of the other end of the rasp bar (300) in upward or
10 downward direction changes the angle of inclination of the rasp bar (300).
17. The method as claimed in claim 15, wherein automatically adjusting the angle of
inclination (A) by the automatic lifting mechanism (304A2) comprises moving the
other end of the rasp bar (300) in upward or downward direction by stroke of a
15 reciprocating actuator (508), thereby changing the angle of inclination (A) of the
rasp bar (300).
18. The method as claimed in claim 14, wherein the angle of inclination (A) is
adjusted manually by a manual lifting mechanism (304M1, 304M2).
20
19. The method as claimed in claim 18, wherein manually adjusting the angle of
inclination (A) by the manual lifting mechanism (304M1) comprises manually lifting
the other end of the rasp bar (300) and fixing it in different synchronous holes (H)
provided on a supporting bracket (601) and the other end of the rasp bar (300).
25
20. The method as claimed in claim 18, wherein manually adjusting the angle of
inclination by the manual lifting mechanism (304M2) comprises lifting the other end
21
of the rasp bar (300) about the pin joint (301) by manually tightening and loosening
nuts (702) about a threaded bolt (703), the nuts (702) and threaded bolt (703)
detachably connecting a supporting bracket (701) to the other end of the rasp bar
(300).