Combine Harvester Straw Chopper Dual Outlet Design
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Solution Overview
Problem
Existing straw choppers in combine harvesters face a trade-off between improved ejection speed of chopped crop residue and reduced chopping performance, leading to increased power consumption, especially with larger machines.
Innovation Solution
The apparatus features a rotor with a central inlet opening and two outlets, one axially aligned and one axially offset, utilizing guide vanes and air vane elements to direct crop residue through spiral paths, optimizing power consumption by minimizing axial conveyance and enhancing spreading patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If air vanes or paddles are added to the chopper rotor to generate accelerating airflow, then ejection speed of chopped straw is improved, but chopping performance is reduced
Solution Approach 1:
The rotor is divided into two distinct functional zones: an inner chopping zone with knives for size reduction and an outer acceleration zone with air vanes for ejection speed enhancement. This segmentation allows each zone to perform its specific function optimally without interfering with the other, resolving the contradiction between chopping quality and ejection speed.
Solution Approach 2:
Different parts of the rotor are given different properties: the inner portion has chopping elements (knives) while the outer portion has air vanes. This local differentiation ensures that the chopping function and acceleration function are performed in their respective optimal locations, maintaining both chopping performance and ejection speed.
2Manufacturing precision
If the passage length of crop residue from inlet to outlet is increased to improve chopping action, then chopping performance is improved, but power consumption is substantially increased
Solution Approach 1:
The material flow path is segmented into two zones: a longer axial path through the chopping zone for effective size reduction, and a shorter tangential path through the ejection zone for efficient discharge. This segmentation allows adequate chopping action without requiring excessive overall passage length, thereby reducing power consumption.
Solution Approach 2:
The rotor utilizes both axial and tangential dimensions for material conveyance. The chopping action occurs primarily in the axial direction while the ejection utilizes the tangential direction. This multi-dimensional approach allows effective chopping without requiring excessive axial passage length, reducing the work required and power consumption.
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 configuration allows for efficient chopping and spreading of crop residue with reduced power consumption and wider spreading patterns, potentially eliminating the need for active spreaders.
Implementation Method 1
a rotor supporting a plurality of blade members which generate a tangential airflow from the feed opening to the discharge opening
Implementation Method 2
air vanes or paddles have been added to the chopper rotor to generate an accelerating airflow
Data Source
AI summary
A straw chopper for a combine harvester including a rotor supporting a plurality of chopping elements. A rotor housing including an inlet opening, an outlet axially aligned with the inlet opening, and at least one outlet that is axially offset from the inlet opening. A portion of the straw is conveyed tangentially to the axially-aligned outlet, whilst a further portion is conveyed from the inlet opening to the axially offset outlet(s) via a path having an axial component, for example a helical path. Guide vanes may be provided on the inside of the housing to impart an axial force upon the straw.