Cutter Bar Linkage Virtual Pivot Below Truss
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Solution Overview
Problem
Agricultural cutter bars in existing systems tend to 'dive' into the ground when encountering obstacles due to the location of the pivot above the cutter bar, leading to inefficiencies and potential damage, as previous solutions with virtual pivots below the cutter bar have not adequately addressed this issue.
Innovation Solution
A cutter bar support linkage with a virtual pivot located below the main truss and at or behind it in the forward direction, utilizing a four-bar linkage configuration with specific pivot orientations and a suspension system to maintain the virtual pivot below the ground level, reducing deflection and the need for additional reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pivot is located above the cutter bar, then the structure is simpler and easier to manufacture, but the cutter bar dives into the ground when encountering obstacles
Solution Approach 1:
The patent inverts the conventional pivot location by positioning the virtual pivot below the cutter bar instead of above it. This is achieved through a four-bar linkage mechanism where the rear link extends backward from the frame to a rear pivot, and the front link extends forward to a front pivot, creating a virtual pivot point below the cutter bar that prevents diving motion while maintaining structural simplicity
2Reliability
If the virtual pivot is located below the cutter bar, then the cutter bar resistance to diving is improved, but the linkage complexity increases
Solution Approach 1:
The patent employs asymmetric link lengths and pivot positions to create the desired virtual pivot location. The rear link is longer than the front link, and the rear pivot is positioned behind the frame while the front pivot is positioned in front of the frame. This asymmetric configuration creates a virtual pivot below the cutter bar that provides effective diving resistance without requiring complex additional components
Solution Approach 2:
The four-bar linkage mechanism serves multiple functions simultaneously: it supports the cutter bar, provides diving resistance through the virtual pivot location, enables height adjustment, and maintains structural integrity. This multi-functionality reduces the need for separate components, thereby limiting the increase in overall device complexity
3Reliability
If the linkage uses uneven-length arms with virtual pivot below, then the cutter bar can rise when striking an object, but the virtual pivot location is prone to rapidly move to above the ground
Solution Approach 1:
The patent positions the virtual pivot below the ground level as a preliminary configuration before any motion occurs. This pre-positioning ensures that during normal operation and obstacle contact, the virtual pivot remains below the ground, providing stable diving resistance. The linkage geometry is designed so that the virtual pivot location is inherently stable and does not rapidly move to above ground level during operation
Data Source
AI summary
An agricultural vehicle header (400) having a frame (402) having a main truss (404) extending in a lateral direction (L), at least one support arm (406) extending from the frame in the forward direction (F), a cutter assembly (410) attached to a respective distal end of each at least one support arm, and a linkage (424) connecting a respective proximal end of each at least one support arm to the frame. The linkage (424) includes a virtual pivot (426, 1008, 1104) located below the main truss, and at or behind the main truss with respect to the forward direction. An agricultural vehicle having the header (400) is also provided.