Friction-Based Torque Limiter for Aircraft Actuator Protection
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Solution Overview
Problem
Existing torque limiters in aircraft turbojet engine actuators are complex, bulky, heavy, and difficult to calibrate, and they do not effectively manage sudden stops, which can lead to damage from accumulated kinetic energy.
Innovation Solution
A torque limiter that uses an abutment capable of preventing rotation of the actuation tube by friction under axial force from the screw, allowing rotation when the axial force exceeds a predetermined torque threshold, with geometric and material characteristics that define a necessary friction torque for movement while limiting the triggering threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional torque limiter is placed downstream in the kinematic chain to protect against sudden stops, then the actuator parts are protected from damage, but the device becomes complex, bulky, heavy, and difficult to calibrate
Solution Approach 1:
The invention extracts the torque limiting function from a separate downstream component and integrates it into the nut itself through a friction surface. This eliminates the need for complex external torque limiters while maintaining protection against sudden stop damage. The nut now performs dual functions: mechanical transmission and torque limitation.
Solution Approach 2:
The invention merges the torque limiting function with the nut component by adding a friction surface to it. This consolidation reduces the number of separate parts, simplifies the overall structure, and eliminates the complexity associated with separate torque limiting mechanisms while maintaining reliable protection.
2Reliability
If a torque limiter is placed downstream to dissipate kinetic energy during sudden stops, then damage to actuator parts is prevented, but the device becomes bulky and heavy
Solution Approach 1:
The invention extracts the energy dissipation function from a separate bulky component and integrates it into the nut through a friction surface. This integration eliminates the need for heavy external torque limiters while maintaining the ability to dissipate kinetic energy during sudden stops through friction.
Solution Approach 2:
The invention merges the energy dissipation function with the nut component. The friction surface on the nut provides kinetic energy dissipation capability without requiring additional heavy components, thus reducing overall weight while maintaining protection against sudden stop damage.
3Reliability
If a torque limiter is placed downstream to protect actuator parts, then reliability is improved, but the device becomes difficult to calibrate with precision
Solution Approach 1:
The invention extracts the calibration complexity from a separate downstream torque limiter and integrates a simpler friction-based mechanism into the nut. This integration maintains protection reliability while simplifying the calibration process to adjusting friction characteristics rather than calibrating a complex mechanical limiter.
Solution Approach 2:
The invention merges the torque limiting function into the nut with a friction surface, which simplifies calibration compared to separate torque limiters. The calibration involves adjusting friction characteristics through material selection or surface treatment rather than precise mechanical adjustment of complex components, improving calibration precision.
4Device complexity
If the abutment prevents rotation by friction under axial force, then the torque limiter becomes simple and compact, but the friction torque must be precisely controlled to allow movement while limiting triggering threshold
Solution Approach 1:
The invention uses parameter changes in the friction surface characteristics (material properties, surface roughness, contact area) to control the friction torque. By adjusting these parameters, the device achieves both simplicity in structure and precision in torque control, allowing movement under normal axial force while triggering at predetermined torque thresholds.
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
This solution results in a simple, compact, reliable, and easily calibratable torque limiter that effectively dissipates kinetic energy during sudden stops, preventing damage to actuator parts.
Implementation Method 1
an abutment capable of: prevent rotation of said tube (105) by friction under the sole effect of an axial force exerted by said screw (101) on said nut during its movement
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a torque limiter for an actuator including a screw (101), a nut mounted on said screw, an actuation tube (105) rigidly connected to the nut and means (109, 133) for rotating said screw, said limiter being characterized in that it includes an abutment (115, 110) capable of: preventing the rotation of said tube (105) by friction simply by an axial force exerted by said screw (101) onto said nut during the movement thereof; and enabling the rotation of said tube (105) when said nut arrives at an axial abutment of said screw beyond a predetermined torque threshold defined by the axial force.