Stratification Pan and Return Pan Grain Chaff Separation
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Solution Overview
Problem
The cleaning unit in conventional combine harvesters is a bottleneck that inhibits the full utilization of modern threshing and separating technology, as it has not kept pace with advancements in capacity, leading to inefficiencies in grain and chaff separation and increased grain loss.
Innovation Solution
The implementation of a combine harvester design featuring a stratification pan and return pan with oscillating motion, where the front of the return pan overlaps the rear of the stratification pan, and crop flow disrupting elements, such as fins, are mounted on the underside of the return pan to enhance stratification of grain and chaff, improving the separation process and capacity of the cleaning unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cleaning unit operates with conventional capacity, then grain loss is minimized, but the bottleneck inhibits utilization of modern threshing and separating technology
Solution Approach 1:
The grain/chaff stream is divided into multiple layers through stratification on the pan, separating grain from chaff before cleaning. This segmentation allows the cleaning unit to process larger volumes without increasing grain loss, as the stratified arrangement enables more efficient air separation.
Solution Approach 2:
Stratification of the grain/chaff mixture occurs on the pan before the material enters the cleaning unit. This preliminary separation action reduces the burden on the cleaning unit, allowing it to operate at higher capacity while maintaining low grain loss through the pre-organized material structure.
2Productivity
If airflow speed is increased to remove more chaff, then cleaning efficiency improves, but grain loss increases
Solution Approach 1:
The grain and chaff are stratified into distinct layers on the pan before entering the cleaning unit. This preliminary arrangement means that when airflow is applied, chaff is removed more efficiently without requiring excessive air speed that would lift and carry away grain, thus reducing grain loss while improving cleaning productivity.
3Use of energy by moving object
If grain and chaff are not stratified, then the cleaning unit must handle mixed material, but stratification allows reduced cleaning airflow
Solution Approach 1:
Stratification of grain and chaff occurs on the pan before cleaning, creating an organized structure that requires less airflow energy for effective separation. This preliminary action reduces the energy demand of the cleaning fan while maintaining or improving cleaning unit capacity through more efficient material processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The enhanced stratification process increases the efficiency of grain and chaff separation, reducing grain loss and improving the capacity of the cleaning unit by allowing the grain to settle more rapidly and the chaff to be effectively removed without affecting the grain, thereby optimizing the utilization of modern threshing and separating technologies.
Implementation Method 1
grain and chaff falls under gravity through a concave grate onto an underlying thresher pan
Implementation Method 2
the thresher pan being driven in an oscillating manner to convey the grain/chaff stream rearwardly
Implementation Method 3
the secondary grain/chaff stream falls under gravity to combine with the primary grain/chaff stream on the stratification pan
Implementation Method 4
the return pan being driven in an oscillating manner to convey the secondary grain/chaff stream forwardly
Implementation Method 5
a fan for generating a cleaning airstream which is directed through the falling grain/chaff stream
Implementation Method 6
The airstream blows the lighter chaff and dust rearwardly and out of the combine whilst the heavier grain falls onto and through a chaffer
Implementation Method 7
a plurality of crop flow disrupting elements are secured to the underside of the return pan above the stratification pan to disrupt the grain/chaff stream and enhance stratification thereof
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A combine harvester (10) comprises a threshing unit (16) arranged to receive and thresh a crop stream. Separating apparatus (24) are located downstream and rearward of the threshing unit (16) and are arranged to receive the threshed crop stream and convey such a rearward direction. The front of a return pan (26), disposed below the separating apparatus (24), overlaps the rear of a stratification pan (22), disposed below the threshing unit (16). The stratification pan (22) is driven in an oscillating manner to convey a primary grain/chaff stream rearwardly to a rear edge (22R) from where the primary grain/chaff stream falls under gravity into a cleaning unit. The return pan (26) is driven in an oscillating manner to convey a secondary grain/chaff stream forwardly to a front edge (26F) from where the secondary grain/chaff stream falls under gravity to combine with the primary grain/chaff stream on the stratification pan (22). The cleaning unit comprises a fan (46) for generating a cleaning airstream which is directed through the falling grain/chaff stream to encourage the lighter material away from the grain. A plurality of crop flow disrupting elements (80) in the form of fins or tines are secured to the underside of the return pan (26) above the stratification pan (22) to disrupt the grain/chaff stream and enhance stratification thereof.