Chopper Rotor Assembly Venting for Combine Harvester Back Pressure
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Solution Overview
Problem
Conventional combine harvester designs experience back pressure buildup due to restricted air flow, despite vents upstream of the chopper rotor, as the close proximity of the chopper rotor housing and fan blades redirects air flow back into the combine.
Innovation Solution
An open-style chopper housing design with a minimal gap between the chopper roof structure and rotor, eliminating rear vents and using thin, flat blades that do not generate additional air streams, allowing air to flow directly through the chopper rotor and out of the combine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional chopper housing with close proximity roof structure and fan blades is used, then chopping function is effective, but air flow is restricted and back pressure builds up
Solution Approach 1:
The chopper housing is segmented into distinct functional zones: an open-style housing for unrestricted air flow, a minimal gap roof structure for directing flow, and a separate chopping zone with flat blades. This segmentation allows the housing to serve dual purposes of chopping and venting without interference.
Solution Approach 2:
Instead of using a traditional enclosed chopper housing that redirects air flow back into the combine, the invention inverts the approach by using an open-style housing that allows air to flow directly through and out of the combine. The roof structure is positioned to minimize gap rather than maximize enclosure, reversing the conventional design logic.
2Stress or pressure
If rear vents are eliminated and open-style housing is used, then back pressure is reduced, but air flow path must be optimized through rotor design
Solution Approach 1:
The chopper rotor serves multiple functions: it chops the crop material and simultaneously acts as an air flow guide. The flat blade design without curved surfaces allows air to pass through unrestricted while the rotor's rotational motion performs the chopping function, combining venting and processing in one component.
Solution Approach 2:
The curved fan blades that generate additional air streams are extracted from the design. Only thin, flat chopping blades remain, which perform solely the chopping function without interfering with air flow. This extraction simplifies the air flow path while maintaining chopping effectiveness.
3Stress or pressure
If thin flat blades without curved surfaces are used, then air flow restriction is minimized, but chopping capability must be maintained
Solution Approach 1:
The blades have local quality differentiation: they are thin and flat along most of their surface to minimize air flow restriction, but have sharpened edges and appropriate spacing to maintain effective chopping capability. This local optimization allows both functions to coexist.
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
This design significantly reduces back pressure by ensuring air flow is not redirected back into the combine, enhancing venting efficiency and reducing pressure within the enclosed body.
Implementation Method 1
a blower disposed in the interior of the housing, the blower configured to generate an air stream in a substantially rearward direction
Implementation Method 2
a chopper rotor assembly disposed within the interior at a location below the rear hood of the housing, the chopper rotor assembly comprising a chopper rotor mounted about a hub for rotation about an axis defined by the hub and a plurality of blades coupled to the hub of the chopper rotor for chopping the residue as it is received via the air stream
Implementation Method 3
a roof structure of the chopper housing located above the chopper rotor, the roof structure being disposed in close proximity to the chopper rotor such that a minimal gap is defined therebetween; wherein, the air stream generated by the blower flows out of the interior via a flow path defined through the chopper rotor without being substantially redirected from flowing in the rearward direction by the plurality of blades of the chopper rotor
Data Source
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AI summary
A combine harvester includes a housing having a rear hood and defining an interior, a blower for generating an air stream in a substantially rearward direction, and a cleaning system separating residue from a crop material such that the residue is transported via the air stream rearwardly to be discharged from the housing. A chopper rotor assembly is disposed within the interior below the rear hood and includes a chopper rotor having a plurality of blades for chopping the residue as it is received via the air stream. A chopper housing is disposed within the interior and includes a roof structure located above the chopper rotor such that a minimal gap is defined therebetween. The air stream flows out of the interior via a flow path defined through the chopper rotor without being substantially redirected from flowing in the rearward direction by the plurality of blades of the chopper rotor.