Screw-Nut Force Sensing Device for Aircraft Flight Control
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Solution Overview
Problem
Aircraft flight control devices require mechanical reducing gears with low friction and play to ensure precision and comfort, but existing gear trains fail to meet these demands due to antagonistic requirements such as low friction and high efficiency across a broad temperature range.
Innovation Solution
A force sensing device utilizing a screw-nut system with rolling elements, which provides low or no play and friction, and high mechanical efficiency, while being less sensitive to temperature variations and cost-effective compared to other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional gear train is used for mechanical reduction, then the device complexity is reduced and manufacturing is easier, but friction and play increase, reducing precision and mechanical efficiency
Solution Approach 1:
The patent replaces the traditional gear train mechanical system with a screw-nut system with rolling elements. This substitution eliminates the meshing gears that cause friction and play, achieving precision without excessive complexity. The rolling elements convert sliding friction into rolling friction, dramatically reducing energy loss while maintaining a relatively simple mechanical structure.
Solution Approach 2:
The patent changes the fundamental operating parameters of the mechanical reduction system by introducing rolling elements between the screw and nut. This parameter change transforms the friction regime from sliding to rolling, enabling high precision and mechanical efficiency while keeping the device structure manageable.
2Force
If a mechanical reducing gear with high reduction ratio is used, then the force sensing capability is improved, but friction and mechanical losses increase
Solution Approach 1:
The patent replaces the traditional gear train with a screw-nut system with rolling elements. This substitution maintains the high reduction ratio needed for force sensing capability while dramatically reducing mechanical losses. The rolling elements minimize friction, ensuring that energy is not lost to heat during the reduction process, thus preserving force sensing accuracy.
Solution Approach 2:
The patent changes the friction regime parameter from sliding to rolling by introducing rolling elements. This parameter change enables the system to achieve high reduction ratios with minimal energy loss, as rolling friction is significantly lower than sliding friction, thereby maintaining force sensing capability while reducing mechanical losses.
3Force
If a gear train is used to achieve high reduction ratio, then the force multiplication is improved, but play and friction increase, reducing control precision
Solution Approach 1:
The patent replaces the gear train with a screw-nut system with rolling elements. This substitution achieves force multiplication through the mechanical advantage of the screw thread while eliminating the play and friction inherent in gear meshing. The rolling elements ensure continuous contact without gaps, maintaining control precision even at high reduction ratios.
Solution Approach 2:
The patent changes the contact mechanism parameter from gear tooth meshing to screw-nut rolling contact. This parameter change eliminates play by ensuring continuous contact through the helical thread geometry, while the rolling elements minimize friction, thereby achieving force multiplication without sacrificing control precision.
4Ease of operation
If a traditional mechanical reducing gear is used, then the device structure is simpler and cost is reduced, but friction varies with temperature, affecting control comfort
Solution Approach 1:
The patent replaces the traditional mechanical reducing gear with a screw-nut system with rolling elements. This substitution provides more stable friction characteristics across temperature variations because rolling friction is less sensitive to temperature changes than sliding friction in gear meshes. The device complexity remains manageable due to the well-established screw-nut mechanism with rolling elements.
Solution Approach 2:
The patent changes the friction regime from sliding to rolling, which fundamentally alters the temperature dependence of friction. Rolling friction exhibits greater thermal stability, ensuring consistent control comfort across the operating temperature range while maintaining a relatively simple device structure.
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
The screw-nut system effectively transmits movement with minimal friction and play, maintaining high efficiency and precision across a wide temperature range, addressing the limitations of traditional gear trains in aircraft flight control devices.
Implementation Method 1
a mechanical reducing gear, which, with a reduction ratio, links the rotation of the action member relative to the support around the primary axis, with the rotation of the rotor relative to the stator around the secondary axis, and which comprises a screw-nut system with rolling elements
Data Source
AI summary
A flight control device of an aircraft including a support, an action member attached to the support rotating freely around a primary axis, a rotary device including a stator, rotatably connected to the support around a secondary axis, and a rotor rotating freely relative to the stator around the secondary axis, the rotary device applying a force sensing torque on the rotor relative to the stator around the secondary axis, and a mechanical reducing gear, which connects, with a reduction ratio, rotation of the action member with rotation of the rotor, the mechanical reducing gear including a screw-nut system with rolling elements, including a screw, attached to the rotor, connected in rotation to the rotor around the secondary axis, and a nut fixed in rotation around the secondary axis relative to the stator and helically connected with the screw around and along the secondary axis via the rolling elements.