Variable Sieve Drive for Combine Harvester Separation
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Solution Overview
Problem
Existing combine harvester cleaning systems are inefficient as they only effectively accelerate seeds and by-products during 25% of the sieve's throw stroke, leading to suboptimal separation and capacity utilization.
Innovation Solution
A rotary drive with an eccentric device and transmission system that cyclically varies the distance between the driving point and the sieve coupling, altering the duration of the accelerating and decelerating portions of the throw and return strokes, allowing for a more efficient sieving process with a higher proportion of time spent accelerating seeds and by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed-length pitman arm is used in the sieve drive assembly, then the structure is simple, but the accelerating portion of the throw stroke only lasts 25% of the total cycle time, reducing sieving effectiveness
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed-length pitman arm with a variable-length mechanism. The transmission system dynamically adjusts the distance between the eccentric device driving point and the sieve coupling during operation, allowing the accelerating portion of the throw stroke to be extended beyond 25% of the total cycle time. This dynamic adjustment optimizes the sieving process by providing longer acceleration time for the seeds and by-products, thereby improving separation effectiveness without requiring additional space in the combine harvester.
2Productivity
If the sieve moves at constant speed during the throw stroke, then the mechanism is simple, but the seeds and by-products only leave the sieve surface at the end of the accelerating portion, limiting separation efficiency
Solution Approach 1:
The patent applies periodic action through the cyclic variation of the transmission system. The distance between the eccentric device driving point and the sieve coupling varies periodically during each full rotation of the rotary drive, creating a rhythmic pattern of acceleration and deceleration. This periodic variation in the transmission geometry ensures that the sieve provides optimal acceleration during the throw stroke, causing seeds and by-products to leave the sieve surface at multiple points throughout the cycle rather than only at the end of the accelerating portion, thereby enhancing separation efficiency.
3Duration of action of moving object
If the transmission system cyclically varies the distance between the driving point and sieve coupling, then the acceleration time is increased, but the transmission mechanism becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the transmission system. The transmission is designed to cyclically vary the distance (a key geometric parameter) between the eccentric device driving point and the sieve coupling during each rotation. This parameter variation allows the system to extend the acceleration duration of the sieve during the throw stroke, providing longer time for seeds and by-products to be accelerated and separated, while managing the complexity through controlled geometric changes rather than adding multiple independent components.
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 increases the capacity and effectiveness of the sieving process by utilizing a larger proportion of time for acceleration, resulting in improved seed separation and increased throughput without the need for additional space within the combine harvester.
Implementation Method 1
an eccentric device, which eccentric device is fixedly connected to the rotatable output shaft of the rotary drive to rotate with the rotatable shaft, which eccentric device has an eccentricity and a driving point, which driving point is rotatable around the center line of the rotatable shaft along a circular path having a radius that equals the eccentricity of the eccentric device
Data Source
Figure 1
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AI summary
The invention pertains to a combine harvester comprising a cleaning system having a sieve that is moveable by a sieve drive assembly which comprises: - a rotary drive, - an eccentric device, which eccentric device has an eccentricity (e) and a driving point (a), - a transmission , that is connected to the eccentric device and to the sieve, which transmission is adapted to cyclically vary the distance between the driving point of the eccentric device and the sieve coupling during each full rotation of the rotatable output shaft of the rotary drive, wherein, due to the cyclic variation of the distance between the driving point (a) of the eccentric device and the sieve coupling (15), during each reciprocating sieve movement at least one of the accelerating portion of the throw stroke, the decelerating portion of the throw stroke, the accelerating portion of the return stroke and the decelerating portion of the return stroke has a duration that is different from the duration of at least one other of said portions of the reciprocating sieve movement.