Tool-Locked Overcenter Door Mechanism for Harvester Access Safety
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Solution Overview
Problem
Large agricultural machines like combine and forage harvesters have complex compartments with difficult access, posing safety risks due to potentially harmful components, and existing access mechanisms lack sufficient safety features to prevent accidental opening during operation.
Innovation Solution
A hinged door with an overcenter mechanism requiring an auxiliary tool for locking and unlocking, ensuring a minimum torque of 1Nm, equipped with a camera for monitoring, providing enhanced safety by preventing manual operation and reminding operators of potential hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple hinged door mechanism is used for aperture access, then ease of operation is improved, but safety is worsened due to risk of accidental opening during operation
Solution Approach 1:
An auxiliary tool (wrench) serves as an intermediary between the operator and the door locking mechanism. The rod with polygonal cross-section requires the wrench to apply sufficient torque to overcome the overcenter mechanism's locking force, preventing accidental opening while still allowing intentional access when needed
2Reliability
If an overcenter mechanism with auxiliary tool is used for locking, then safety is improved by preventing manual unlocking, but device complexity increases
Solution Approach 1:
The overcenter mechanism is designed to be self-locking through its geometric configuration. Once the rod is rotated to the locked position, the mechanism automatically engages the locking action without requiring additional actuators or control systems, maintaining simplicity while ensuring safety
3Reliability
If the rod requires minimum torque of 1Nm for pivoting, then safety against accidental opening is improved, but ease of operation deteriorates due to requiring auxiliary tool
Solution Approach 1:
The rod is designed with a polygonal cross-section (square or hexagonal) rather than a circular one. This parameter change in geometry creates flat surfaces that engage with corresponding features in the locking mechanism, requiring specific torque application through the auxiliary tool to overcome the overcenter mechanism's locking force
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
In an agricultural implement according to the invention, for example a combine harvester, a hinged door (6) provides access to an aperture (12) in a wall (2) of a walled compartment (1). A camera may be attached to said door, for monitoring the interior of the compartment. The door (6) is configured to be locked and unlocked by an overcenter mechanism (7) characterized in that it requires an auxiliary tool for locking and unlocking the mechanism. In particular, the mechanism comprises a pivotable rod (14) pivotable about a first pivot axis (15) relative to the door, and an overcenter arm (21) that is pivotable at one end relative to a lever (20) fixed to or integral with the rod (14). The other end of the overcenter arm is attachable to the wall (2) comprising the aperture (12) covered by the door. The overall dimensions of the mechanism are such that pivoting the rod (14) to thereby lock or unlock the mechanism requires an auxiliary tool. The rod could for example be provided with a polygonal cross-section, necessitating the use of a wrench (35) or similar gripping tool for pivoting the rod.