Patent ID: 7297052
Filing Date: 2007-11-20
Classification: A01D,A01F

Abstract:
1. A method for optimizing the operation of a grain cleaning system in a combine harvester during harvesting, said grain cleaning system comprising an upper chaffer sieve and a lower grain sieve disposed the one above the other, the upper and lower sieves having openings to permit passage of crop material by gavity through the openings of the upper and lower sieves, wherein the size of the openings of the upper sieve are adjustable, said method comprising: harvesting a crop and guiding said harvested crop to a threshing and separating system in order to separate desired crop material from undesired crop material; guiding at least part of said separated crop material to said grain cleaning system; cleaning the separated crop material in said grain cleaning system by passing the material over the upper and lower sieves, whereby material that is not discarded from the combine harvester and that does not pass through the opening of the lower grain sieve is returned to the front end of the grain cleaning system for repeating the cleaning action thereby creating a material return flow; and adjusting the openings of the upper sieve to enlarge the size of the openings for a period of time in response to registering a deviance from a threshold value for crop material load on the upper sieve such that the material return flow is adjusted wherein the deviance from the threshold value for crop material load on the upper sieve is registered by a sieve loss sensor system provided adjacent the upper sieve.