DEVELOPMENT OF A MULTI-DIMENSIONAL CLEANING SIEVE TO OPTIMIZE THRESHED OUTPUTS DISTRIBUTION AND EXPERIMENTS IN COMBINE HARVESTER

Searching for and identifying methods to reduce grain cleaning loss, grain impurity, and improve cleaning efficiency is crucial for processing threshed rapeseed outputs in uneven conditions. Leveling a single-degree-of-freedom cleaning sieve becomes particularly challenging under terrain undulations and limited cleaning space. Based on spiral theory and mechanical design principles, this study explores a multi-degree-of-freedom cleaning sieve capable of vertical movement along the horizontal plane and rotation around its center. This design allows the sieve to adjust its relative angle, enabling a more uniform distribution of threshed outputs. A CFD-DEM coupling method was used to simulate the movement of these outputs. The cleaning sieve inclined forward and to the right served as the experimental group, while a horizontal cleaning sieve functioned as the control group. Compared to the control, the experimental group showed a 14.6% reduction in grain loss and a 2.3% decrease in impurities. Furthermore, the centroid motion of the rapeseed was enhanced prior to sieving, facilitating more effective separation, while the movement speed of impurities outside the cleaning shoe increased, aiding impurity removal.