Straw Walker Covering Gradient Angle for Crop Mat Prevention
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Solution Overview
Problem
In combine harvesters, the formation of dense mats of short straw, ears, and chaff on the straw walkers' decks leads to clogged passage openings and uneven conveying speeds, impeding grain separation, especially during dry crop harvesting.
Innovation Solution
The straw walkers' coverings and shaker combs have different pitch angles, with the coverings having a smaller slope angle than the combs, preventing mat formation and ensuring uniform conveying speeds for both crop streams, thereby enhancing grain separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the covering and shaker combs have the same gradient angle, then the structure is simple and uniform, but dense mats of crop material form on the covering, clogging the openings and impeding grain separation
Solution Approach 1:
The patent applies local quality by differentiating the gradient angles of different components. The covering has a first gradient angle while the shaker combs have a second gradient angle that is greater than the first. This local differentiation prevents uniform mat formation while maintaining structural functionality, resolving the contradiction between reliability and device complexity.
2Reliability
If the covering has a smaller gradient angle than the shaker combs, then mat formation is prevented and grain separation is improved, but the structure becomes more complex
Solution Approach 1:
The patent changes the geometric parameter (gradient angle) of the covering relative to the shaker combs. By setting the covering's gradient angle lower than that of the shaker combs, the patent alters the flow dynamics of crop material, preventing mat formation and improving grain separation efficiency while accepting increased structural complexity.
3Productivity
If the pitch angle of the covering is 8° to 18°, then crop mat formation is avoided and conveying speed is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a parameter range (8° to 18°) for the covering's pitch angle that optimizes conveying speed and prevents mat formation. This parameter change improves productivity while the range provides flexibility in manufacturing, balancing precision requirements with performance goals.
Data Source
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AI summary
The harvester (1) has a separating mechanism provided with a set of straw-walkers (13) arranged next to each other, where the straw-walkers have a lining, which is fastened between two lateral shaker combs projecting the lining. The lining is provided with openings for separation of grains from a grain straw mixture. The lining and the shaker combs are arranged in a conveying direction. The lining and the shaker combs exhibit different large pitch angles in sections, where the shaker combs exhibit a constant pitch angle over the entire length of the straw-walkers.