Below is a list of excerpts from Claas patents relating to the subject of "choppers".
Note: The decisive factor for a patent is always the "claims", as specifically what exactly the applicant claims as his invention!
This application claims a special arrangement of the knives on the knife drum, which is intended to achieve particularly smooth running:
https://worldwide.espacenet.com/patent/search/family/007640724/publication/EP1151661A1?q=EP1151661
This application relates to the "EasyCollect" harvesting attachment with its endlessly revolving conveyor chains and the type and arrangement of the drivers and the knives/counter knives:
https://worldwide.espacenet.com/patent/search/family/062947906/publication/EP3430882A1?q=EP3430882
This application is about a conveyor channel that can carry out an evasive movement if the feed mass is too large. The "Varistream" system will most likely be based on this patent:
https://worldwide.espacenet.com/patent/search/family/034978865/publication/EP1604563A1?q=EP1604563B1
Here is the patent regarding the different positions of wheel hub motors to compensate for the ground clearance with different tires: