Geneva Motion Controller for High-Torque CVT Indexing
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Solution Overview
Problem
Existing Geneva drive systems are unsuitable for high-torque applications and cannot halt indexing processes while the machine is running, making them impractical for continuously variable transmissions (CVT) in light motor vehicles, where rapid ratio shifting with high torque requirements is necessary.
Innovation Solution
A Geneva motion controller with rotatable input and output shafts, a six-armed Geneva wheel, and independently operable Geneva wheel cam units that can engage and partially rotate the wheel in predetermined increments, allowing for demand-based indexed rotation and locking mechanisms to manage high torque shifts efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large and quick-acting servo or hydraulic system is employed to achieve high torque ratio shifting, then the torque requirement is met, but the device becomes impractical for light motor vehicles due to size and complexity
Solution Approach 1:
The indexing mechanism is divided into discrete incremental steps using a Geneva wheel with multiple arms. The lead screw nut rotates in fixed increments (e.g., 60°) rather than continuously, breaking down the large torque requirement into manageable discrete movements that can be achieved with smaller actuators.
Solution Approach 2:
The system uses periodic engagement of cam units with the Geneva wheel to achieve intermittent indexing motion. The cam units engage the Geneva wheel arms at specific intervals, providing torque only when needed for ratio shifting, rather than requiring continuous high-torque delivery throughout the entire cycle.
2Measurement precision
If the indexing process is halted to allow ratio shifting, then precise ratio control is achieved, but the machine cannot run continuously which reduces productivity
Solution Approach 1:
The Geneva wheel mechanism allows the output shaft to continue rotating continuously while the indexing action occurs periodically at specific intervals. The cam units engage the Geneva wheel arms during predetermined portions of the rotation cycle, maintaining continuous motion while achieving precise intermittent indexing for ratio shifts.
Solution Approach 2:
The indexing mechanism operates periodically within the continuous rotation cycle. The cam units engage the Geneva wheel at specific intervals to provide incremental indexing movements, allowing the machine to maintain continuous operation while achieving precise ratio control at predetermined moments.
3Measurement precision
If the Geneva wheel is engaged continuously for indexing, then precise incremental rotation is maintained, but the system cannot accommodate bidirectional ratio shifting
Solution Approach 1:
The indexing system is segmented into multiple independent cam units, each responsible for indexing in a specific direction. The first cam unit provides indexing in one direction while the second cam unit provides indexing in the opposite direction, allowing bidirectional ratio shifting while maintaining precise incremental control through the Geneva wheel mechanism.
Solution Approach 2:
The system dynamically switches between different cam units based on the required direction of indexing. The cam units are positioned and configured to engage the Geneva wheel arms in opposite rotational directions, allowing the system to adapt its indexing direction dynamically while maintaining precise control through the Geneva wheel's inherent positioning accuracy.
Data Source
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AI summary
The invention relates to a Geneva motion controller (10) for operating a machine in forward and reversed indexed increments on demand. The controller includes a Geneva wheel (18) which is rotatable with and slidable on the controller output shaft (16), two cam units (20, 22) which are rotatable on axes which are parallel to and located on opposite sides of the output shaft axis, each cam unit including three axially spaced formation arrangements with the central formation of both cam units being adapted to lock the Geneva wheel (18) against rotation while enabling continued rotation of the cam units (20, 22) with the upper formation arrangement of the first of the cam units (22) including a downwardly directed Geneva wheel engaging formation and the lower formation arrangement of the second cam unit (20) an upwardly projecting formation, and a cammed trigger unit for moving the Geneva wheel into contact with any of the three cam unit formation arrangements.