Cutting Tool Lever Actuation Mechanism for Agricultural Crop Selectors
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Solution Overview
Problem
Existing cutter mechanisms for straw-shaped agricultural crops require complex and expensive selector shafts to manage cutting length, which are prone to wear due to high forces involved in switching knives between active and inactive positions.
Innovation Solution
A mechanism where a power-operated actuator controls the movement of levers between operative and inoperative positions, while a separate selector shaft independently selects the number of knives to be active, decoupling these functions to simplify and reduce the complexity and cost of the selector shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shaft controls both lever movement and knife selection, then the mechanism is compact, but the shaft experiences high forces and premature wear
Solution Approach 1:
The control mechanism is divided into two independent shafts: a first shaft that controls lever movement between active and inactive positions, and a second shaft that selects which knives become active. This segmentation separates the high-force lever control function from the low-force knife selection function, preventing the selector shaft from experiencing excessive wear while maintaining a compact overall structure.
2Reliability
If cam discs are dimensioned to withstand high forces, then reliability improves, but manufacturing cost increases
Solution Approach 1:
The function of controlling knives is separated from the high-force lever actuation. The second shaft with cam discs only needs to overcome spring forces for knife selection, not the full force required to move levers. This allows cam discs to be manufactured at lower cost while maintaining sufficient durability for their reduced load requirements.
Solution Approach 2:
The high-force lever control function is extracted from the selector shaft system and assigned to the first shaft. This removes the excessive force burden from the cam discs on the second shaft, allowing them to be designed and manufactured with lower specifications and reduced cost while maintaining adequate reliability for knife selection.
3Adaptability or versatility
If the selector shaft is moved independently, then cutting length selection is flexible, but damage may occur if moved before levers are positioned
Solution Approach 1:
A coupling mechanism provides feedback control between the two shafts. The coupling only permits movement of the second shaft (knife selection) when the first shaft is in the correct position (levers in inactive position). This feedback control ensures proper sequencing of operations, allowing flexible cutting length selection while preventing mechanism damage by blocking improper shaft movements.
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 wear on the selector shaft, making it less expensive and more reliable, allowing for efficient selection of cutting length without risking damage to the mechanism during operation.
Implementation Method 1
springs associated with the levers biasing the associated lever towards the operative position
Implementation Method 2
it comes into an inactive position, in which it does not extend into the channel, by the action of gravity and/or by the oncoming crop
Data Source
Figure 1
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Figure 3
AI summary
The cutting unit has an actuator (74) which is moved between two positions, where the actuator is operated by external force independent of a selector shaft (72). All levers (52) are placed in the outer operation position in the former position. The levers reach in the operation position in the latter position and the selector shaft is arranged to fix the lever of a non selected knife (40) in the outer working position. The selected knife reaches in the active position by the effect of a spring (62) by the actuator placed in the latter position. An independent claim is included for a lever with two arms.