Cleaning system for a combine

1. A grain cleaning system for a combine, the grain cleaning system comprising:

a front roller;

a rear roller spaced in a rearward direction from the first roller;

a conveyor belt having an upper surface extending from the front roller to the rear roller;

a motor operatively connected to the conveyor belt and configured to drive the upper surface in a belt travel direction from the front roller to the rear roller;

a baffle located adjacent the rear roller, the baffle having a leading edge, a trailing edge located behind the leading edge with respect to the belt travel direction and below the leading edge with respect to a vertical direction, and a baffle surface extending from the leading edge to the trailing edge, the baffle positioned adjacent the rear roller such that there is a gap between the conveyor and the baffle sized to accommodate a passage of a combination of grain and material other than grain carried by the conveyor;

one or more sieves located below the baffle; and

a fan configured to direct an airflow at least partially upwards in the vertical direction adjacent the rear roller.

2. The grain cleaning system of claim 1 , wherein the motor is configured to be operated to drive the combination of grain and material other than grain into contact with the baffle.

3. The grain cleaning system of claim 1 , wherein the conveyor belt comprises one or more paddles extending from an outer surface of the conveyor belt.

4. The grain cleaning system of claim 3 , wherein the one or more paddles extend a first distance from the outer surface of the conveyor belt, and the baffle is located at its nearest point at a second distance from the outer surface of the conveyor belt, the second distance being greater than the first distance.

5. The grain cleaning system of claim 4 , wherein the first distance is between 50% and 95% of the second distance.

6. The grain cleaning system of claim 1 , further comprising one or more belt actuators configured to move at least one of the first roller and the second roller in the vertical direction to thereby change the orientation of the belt travel direction.

7. The grain cleaning system of claim 1 , further comprising one or more baffle actuators configured to move one or both of the leading edge and the trailing edge in the vertical direction.

8. A method for cleaning grain in a combine, the method comprising:

operating a conveyor belt to move a combination of grain and material other than grain in a belt drive direction;

expelling the combination of grain and material other than grain from the conveyor belt in the belt drive direction, the expelling comprising forcing the combination of grain and material other than grain to pass through a gap between an outer surface of the conveyor belt and the baffle;

contacting the expelled combination of grain and material other than grain with a baffle to force the combination of grain and material other than grain to move at least partially downwards in a vertical direction; and

directing an airflow at least partially upwards in the vertical direction to intersect the downwardly-directed combination of grain and material other than grain, to thereby separate at least some of the material other than grain from the grain.

9. The method of claim 8 , wherein operating the conveyor belt to move the combination of grain and material other than grain comprises pushing the combination of grain and material other than grain with one or more paddles extending from an outer surface of the conveyor belt.

10. The method of claim 9 , wherein expelling the combination of grain and material other than grain from the conveyor belt comprises forcing the combination of grain and material other than grain to pass through a gap between the outer surface of the conveyor belt and the baffle, wherein the one or more paddles extend a first distance from the outer surface of the conveyor belt, and a minimum distance of the gap between the outer surface of the conveyor belt and the baffle is greater than the first distance.

11. The method of claim 10 , wherein the first distance is between 50% and 95% of the minimum distance.

12. The method of claim 8 , further comprising moving at least one part of the conveyor belt relative to another part of the conveyor belt to thereby change the orientation of the belt travel direction.

13. The method of claim 8 , further comprising moving the baffle to alter the position of the baffle relative to the belt travel direction.

14. An agricultural combine comprising:

a threshing and separating system; and

a header configured to direct crops into the threshing and separating system;

wherein the threshing and separating system comprises a grain cleaning system comprising:

a front roller;

a rear roller spaced in a rearward direction from the first roller;

a conveyor belt having an upper surface extending from the front roller to the rear roller;

a motor operatively connected to the conveyor belt and configured to drive the upper surface in a belt travel direction from the front roller to the rear roller;

a baffle located adjacent the rear roller, the baffle having a leading edge, a trailing edge located behind the leading edge with respect to the belt travel direction and below the leading edge with respect to a vertical direction, and a baffle surface extending from the leading edge to the trailing edge, the baffle positioned adjacent the rear roller such that there is a gap between the conveyor and the baffle sized to accommodate a passage of a combination of grain and material other than grain carried by the conveyor;

one or more sieves located below the baffle; and

a fan configured to direct an airflow at least partially upwards in the vertical direction adjacent the rear roller.

15. The agricultural combine of claim 14 , wherein the motor is configured to be operated to drive the combination of grain and material other than grain into contact with the baffle.

16. The agricultural combine of claim 14 , wherein the conveyor belt comprises one or more paddles extending from an outer surface of the conveyor belt.

17. The agricultural combine of claim 16 , wherein the one or more paddles extend a first distance from the outer surface of the conveyor belt, and the baffle is located at its nearest point at a second distance from the outer surface of the conveyor belt, the second distance being greater than the first distance.

18. The agricultural combine of claim 13 , wherein the first distance is between 50% and 95% of the second distance.

19. The agricultural combine of claim 14 , further comprising one or more belt actuators configured to move at least one of the first roller and the second roller in the vertical direction to thereby change the orientation of the belt travel direction.