Pivot-Mounted Dual Load Path Actuator for Linkage Fault Detection
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Solution Overview
Problem
Existing horizontal stabilizer trim actuators (HSTAs) lack redundancy and fault detection mechanisms, making them vulnerable to single-point failures such as wear or backlash in drive linkages, which can lead to loss of control and safety issues.
Innovation Solution
A dual load path actuator assembly with independently driven screw drives and synchronized gearing, coupled with a pivot mount and proximity detectors to detect force imbalances, ensuring safe operation even if one load path fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single load path actuator is used, then the device complexity is reduced, but the reliability is compromised due to lack of redundancy
Solution Approach 1:
The actuator is divided into two independent sub-actuators (first sub-actuator 30 and second sub-actuator 60), each with its own motor and drive linkage, forming separate load paths. This segmentation provides redundancy so that if one sub-actuator fails, the other can maintain operation, resolving the contradiction between reliability and complexity by distributing function across independent segments.
Solution Approach 2:
The proximity detectors (40, 41, 70) are positioned to detect force imbalances before they lead to catastrophic failure. The system monitors the operational state continuously and can trigger protective actions or alerts before the fault propagates, cushioning against the full impact of potential failures and maintaining reliability without requiring overly complex protective systems.
2Reliability
If dual load path actuator with fault detection is implemented, then the reliability is improved through redundancy, but the device complexity increases
Solution Approach 1:
The pivot mount (81) serves multiple functions: it connects both drive linkages to the driven object, acts as a force balance indicator through its orientation, and provides a mechanical interface for the proximity detectors. This multi-functionality reduces the need for separate components, allowing the dual load path system to achieve high reliability without proportionally increasing complexity.
Solution Approach 2:
The system uses its own operational characteristics (force balance in the pivot mount) as the detection mechanism. The proximity detectors monitor the natural equilibrium position of the pivot mount, which self-indicates when one load path develops excessive wear or backlash. This self-service approach to fault detection avoids adding complex external monitoring systems.
3Duration of action of stationary object
If wear or backlash develops in drive linkage, then the operational duration is extended, but the reliability deteriorates due to undetected faults
Solution Approach 1:
The proximity detectors provide continuous feedback on the force balance condition of the pivot mount. When wear or backlash develops in one drive linkage, the resulting force imbalance shifts the pivot mount orientation, which the detectors immediately sense. This feedback loop allows the system to detect faults early and respond before reliability deteriorates, even as operational duration extends.
Solution Approach 2:
The system takes preliminary action by detecting force imbalances caused by wear or backlash before they lead to complete failure. The proximity detectors monitor the pivot mount position continuously, and when a threshold is exceeded indicating significant wear, the system can alert operators or automatically adjust operation to protect against further degradation, maintaining reliability throughout extended operational periods.
Data Source
AI summary
An actuator comprising first and second motors, first and second drive linkages, and a pivot mount configured to pivot about a pivot axis, the pivot mount connected to the first and second drive linkages at first and second mount connections offset first and second offset distances from the pivot axis, the motors and first and second drive linkages configured to provide first and second load paths between a drive housing and the pivot mount so that in a first operation state the pivot mount is in a force-balanced orientation about the pivot axis, and a proximity detector positioned to detect when the pivot mount rotates about the pivot axis above a threshold out of the force-balanced orientation, wherein a force imbalance on the pivot mount caused by a fault in one of the first or second drive linkages above a threshold is detected by the proximity detector.