Spindle Drive Redundancy via Torsion Bar Sensor
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Solution Overview
Problem
Existing spindle drives for aircraft components lack redundancy, making it critical to ensure continued functionality even if one load path fails, and there is no effective means to detect such failures during flight.
Innovation Solution
A spindle drive design incorporating a primary load path formed by a spindle and a secondary load path formed by a torsion bar, with a sensor unit to detect relative movement between the spindle and torsion bar, allowing actuation via the other path and indicating defects, utilizing a torsion bar connected to the spindle via bolts, wedge-shaped sections, and springs for torque and axial force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single load path (spindle only) is used in the spindle drive, then the device complexity is reduced, but the reliability is compromised because there is no redundancy to ensure continued functionality in case of defect
Solution Approach 1:
The load transmission path is segmented into two independent paths: the primary path through the spindle and the secondary path through the torsion bar. This segmentation allows each path to function independently, providing redundancy while maintaining a relatively simple overall structure. The torsion bar is positioned concentrically within the spindle, creating distinct functional segments that can operate separately.
Solution Approach 2:
The torsion bar is pre-installed and pre-tensioned within the spindle structure as a backup load path. In normal operation, the spindle carries the primary load, but the torsion bar is already in place and ready to immediately assume the load if the spindle fails. This beforehand preparation ensures continuity of function without requiring complex real-time switching mechanisms.
2Reliability
If no defect detection mechanism is implemented, then the device complexity is reduced, but the ability to detect and respond to failures is lost
Solution Approach 1:
A sensor unit is integrated into the spindle structure to continuously monitor the relative position between the spindle and torsion bar. This sensor provides real-time feedback about the operational state of the load paths. When the spindle fails, the torsion bar rotates relative to the spindle, and this relative movement is detected by the sensor, which then generates a defect signal. This feedback mechanism enables automatic defect detection without requiring complex external monitoring systems.
Solution Approach 2:
The defect detection system utilizes the inherent relative movement between the spindle and torsion bar during normal operation and failure conditions. The sensor unit is positioned to automatically detect this relative movement without requiring additional actuators or complex measurement systems. The system essentially monitors itself by detecting the natural mechanical behavior changes that occur when a defect happens.
3Force
If the torsion bar is rigidly connected to the spindle throughout its length, then the torque transmission is improved, but the ability to detect relative movement for defect indication is reduced
Solution Approach 1:
The connection between the torsion bar and spindle exhibits local quality variations: at certain locations (such as the ends), the connection is rigid to ensure effective torque transmission, while at other locations (where the sensor is positioned), the connection allows controlled relative movement. This localized differentiation enables both functions to coexist: rigid connections where force transmission is critical and flexible connections where measurement is required.
Solution Approach 2:
A sensor unit acts as an intermediary element positioned between the spindle and torsion bar. This intermediary detects the relative movement caused by torsion bar rotation while allowing the torque transmission function to proceed undisturbed. The sensor translates the mechanical relative movement into an detectable signal without interfering with the primary torque transmission path.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continued actuation of aircraft components by detecting and compensating for failures in either load path, ensuring aircraft control and safety by generating signals for defective conditions, thereby maintaining functionality during flight.
Implementation Method 1
a second load path which is formed by a torsion bar which is exposed to torsion, which is arranged in the spindle and is connected to it such that a rotary movement is exerted onto the spindle in at least one state of the threaded drive by the torsion bar
Implementation Method 2
the torsion bar is connected to the spindle or to the sensor unit by a spring which exerts a force acting in the axial direction. The spring can be a compression spring.
Data Source
AI summary
The present invention relates to a spindle drive having a first load path which is formed by the spindle and having a second load path which is formed by a torsion bar which is exposed to torsion, which is arranged in the spindle and is connected to it such that a rotary movement is exerted onto the spindle in at least one state of the threaded drive by the torsion bar, with the spindle drive having a sensor unit which is made such that it detects a relative movement between the spindle and the torsion bar.