Dual-Drive Linear Actuator for Jam-Tolerant Motion
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Solution Overview
Problem
Rotary-to-linear actuators are prone to failures such as jamming and component breakdowns, which can prevent translational linear movement, leading to partial or complete actuator failure.
Innovation Solution
A linear actuator system with dual drive systems, including a primary and secondary rotary component, where the secondary drive system is activated upon failure of the primary, allowing the actuator to continue operation by rotating the secondary shaft portion relative to the primary, ensuring continuous motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single drive system is used in a linear actuator, then the device complexity is reduced, but the reliability deteriorates due to potential failures such as jamming and component breakdowns
Solution Approach 1:
The drive system is segmented into multiple independent drive systems (first drive system with first rotary component, second drive system with second rotary component), each capable of independently actuating the linear shaft arrangement. This segmentation allows the actuator to continue operation if one drive system fails, thereby improving reliability without significantly increasing overall system complexity.
Solution Approach 2:
The patent changes the operational parameter from a single drive system to multiple drive systems with different axial positions. By introducing a second drive system at a different axial position than the first, the system achieves redundancy and improved reliability while maintaining a compact structure that doesn't excessively increase complexity.
2Reliability
If a second drive system is added as backup, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Both the first and second drive systems are designed with the same functional capability to actuate the linear shaft arrangement. Each drive system can independently perform the full actuation function, making them universal and interchangeable. This multi-functionality ensures that if one drive system fails, the other can immediately take over without requiring additional specialized components, thus improving reliability while controlling complexity.
Solution Approach 2:
The second drive system is pre-configured and positioned at a different axial location before any failure occurs. The control system is pre-programmed to detect failures and switch to the second drive system. This preliminary preparation ensures immediate failover capability without requiring complex real-time decision-making or additional components during the failure event.
3Duration of action of moving object
If the second shaft portion moves relative to the first shaft portion upon failure, then the continuous operation is maintained, but the manufacturing precision requirements increase
Solution Approach 1:
The second shaft portion is nested within or alongside the first shaft portion along the longitudinal axis, with both shafts capable of independent linear movement. This nested arrangement allows the second shaft portion to take over the actuation function if the first shaft portion fails, maintaining continuous operation. The nesting design facilitates compact packaging while managing the precision requirements for relative positioning and movement between the two shafts.
Data Source
AI summary
A linear actuator arranged to convert rotary motion to linear motion. The linear actuator includes a linear shaft arrangement, having a first shaft portion and a second shaft portion and extends along a longitudinal axis (A) of the linear actuator. At least one of the first shaft portion and the second shaft portion of the linear shaft arrangement can be translated linearly along the longitudinal axis upon actuation. A first drive system has a first rotary component extending at least partially around the longitudinal axis. A second drive system has a second rotary component extending at least partially around the longitudinal axis at a different axial position to the first drive system. The linear actuator, when the first drive system fails, allows rotation of the second rotary component so that the second shaft portion moves relative to the first shaft portion.