Cleaning Shoe Drive Linkage Phase Offset
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Solution Overview
Problem
Conventional combine harvester cleaning shoes experience significant variations in drive shaft speed, belt displacement, and power requirements due to out-of-phase reciprocation of the chaffer and sieve, leading to inefficient operation and increased wear on components.
Innovation Solution
A cleaning shoe design with a drive shaft featuring cams that are angularly offset by a phase angle between 160 and 100 degrees, driving links that reciprocate the chaffer and sieve out of phase, thereby reducing force and speed variations and minimizing load on the drive system without adding significant weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chaffer and sieve are driven by links from a crankshaft at opposite angular orientations, then both components can be driven simultaneously, but significant variations in drive shaft speed, belt displacement, and power requirements occur due to out-of-phase reciprocation
Solution Approach 1:
The patent applies asymmetry by offsetting the phase angle between the chaffer and sieve reciprocation from the conventional 180 degrees to a range of 100-160 degrees. This asymmetric adjustment in the timing relationship between the two reciprocating components reduces the peak-to-valley variations in drive shaft speed, belt displacement, and power requirements, thereby improving reliability while maintaining productivity
Solution Approach 2:
The patent changes the critical parameter of phase angle from 180 degrees to 100-160 degrees. This parameter modification optimizes the reciprocation timing to minimize force and speed variations in the drive system, reducing component wear and extending lifespan without sacrificing cleaning performance
2Productivity
If the chaffer and sieve reciprocate out of phase, then cleaning separation is effective, but force and speed variations increase leading to increased wear on components
Solution Approach 1:
By modifying the phase angle parameter to 100-160 degrees, the patent reduces the extreme force and speed variations that cause component wear. This optimized timing maintains effective grain separation while minimizing the harmful mechanical stresses on links, cams, and the drive shaft, thereby extending component lifespan
3Reliability
If the drive shaft is designed to reduce force and speed variations, then component wear is reduced, but the complexity of the drive system increases
Solution Approach 1:
The patent achieves reduced component wear through a relatively simple parameter change (phase angle adjustment to 100-160 degrees) rather than implementing a complex variable speed drive or multiple drive shafts. This maintains reliability improvements while keeping the drive system configuration manageable and cost-effective
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 reduces variations in drive shaft speed, belt displacement, and power requirements, resulting in smoother and more efficient operation, reducing wear on components and extending their lifespan.
Implementation Method 1
The drive shaft includes a first cam and a second cam. The first cam is coupled to the first end of the first link, and the second cam is coupled to the first end of the second link. The rotation of the drive shaft drives the first link to reciprocate the chaffer and drives the second link to reciprocate the sieve.
Data Source
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AI summary
A cleaning shoe for an agricultural machine includes a chaffer supported for movement relative to a chassis, a sieve positioned below the chaffer and supported for movement relative to the chassis. The cleaning shoe also includes a first link, a second link, and a drive shaft. The first link includes a first end and a second end coupled to the chaffer. The second link includes a first end and a second end coupled to the sieve. The drive shaft rotates about a shaft axis and includes a first cam and a second cam. The first cam is coupled to the first end of the first link, and the second cam is coupled to the first end of the second link. Rotation of the drive shaft drives the first link to reciprocate the chaffer and drives the second link to reciprocate the sieve. The second cam is angularly offset relative to the first cam by a phase angle less than 180 degrees about the shaft axis.