Rotor Transmission Joint With Roller CV Coupling for Fatigue Life
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Solution Overview
Problem
Current transmission joints for tilt-rotor aircrafts, which rely on elastomeric bearings, suffer from reduced fatigue life, increased cost and weight, and complex maintenance due to overheating and the need for frequent inspection, particularly during prolonged flights.
Innovation Solution
A transmission joint design featuring a constant velocity joint with rollers and chambers that allows oscillation between the hub and control shaft, utilizing dampening elements with alternating layers of elastomeric materials and steel to manage torque and aerodynamic forces, and stop elements to limit oscillation angles, decoupling torque and force transmission paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If elastomeric bearings are used to transmit torque and aerodynamic forces in the articulated joint, then the joint can accommodate oscillations between the hub and control shaft, but the fatigue life is reduced and the cost and weight increase
Solution Approach 1:
The patent divides the force transmission function into two separate paths: elastomeric bearings handle only torque transmission while steel spherical bearings handle aerodynamic forces. This segmentation allows each bearing type to be optimized for its specific function, improving overall reliability while maintaining oscillation accommodation capability.
2Strength
If elastomeric bearings are hyperstatically constrained to transmit both torque and aerodynamic forces, then the transmission joint can maintain structural integrity, but the weight and cost increase
Solution Approach 1:
The patent segments the load-bearing function into two independent bearing systems: elastomeric bearings for torque and steel spherical bearings for aerodynamic forces. This eliminates the need for hyperstatic constraint of elastomeric bearings, reducing weight while maintaining structural integrity through the complementary steel bearing support.
3Ease of operation
If elastomeric material components are used in the transmission joint, then the joint can provide damping and flexibility, but the components overheat during prolonged flights requiring temperature monitoring
Solution Approach 1:
The patent segregates the damping function (handled by elastomeric bearings for torque) from the high-temperature force transmission function (handled by steel spherical bearings for aerodynamic forces). This segmentation reduces the thermal load on elastomeric materials while preserving their damping benefits.
4Power
If the articulated joint uses a conventional design with elastomeric bearings, then the joint can transmit torque and forces, but frequent inspection and replacement are required increasing maintenance complexity
Solution Approach 1:
The patent segments the bearing system into two independent subsystems with different material properties and failure modes. The steel spherical bearings handle high-load aerodynamic forces with superior durability, reducing maintenance frequency for the critical force transmission path while elastomeric bearings handle torque with their inherent damping benefits.
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 design enhances the fatigue life, reduces weight and cost, simplifies maintenance, and prevents overheating by independent lubrication and easy replacement of components, while maintaining efficient torque and force transmission.
Implementation Method 1
dampening elements with alternating layers of elastomeric materials and steel to manage torque and aerodynamic forces
Implementation Method 2
a transmission joint design featuring a constant velocity joint with rollers and chambers that allows oscillation between the hub and control shaft
Data Source
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AI summary
An articulated transmission joint (20; 20'; 20") for connecting a control shaft (10) to a hub (15) of a rotor (8, 8', 8"), comprising: a first element (45, 45', 45") rotatable about a first axis (C); a second element (50, 51, 52; 50", 51", 52") rotatable about a second axis (D); and connecting means (60, 60', 60") to allow transmitting the motion between the first and the second element (45, 45', 45"; 50, 51, 52; 50", 51", 52") of a torque having a main component along the first axis (C) and a torque having a main component along the second axis (D); the connecting means (60, 60', 60") comprise, a roller (54) articulated on the first element (45, 45', 45''); and a chamber (53) defined at least partially by the second element (50, 51, 52; 50", 51", 52") and housing at least partially the roller (54); the chamber (53) is delimited towards the roller (54) by a first surface (59) that contacts the roller (54) circumferentially to the first axis (C), after the rotation of the first element (45) about the first axis (C); the first and second element (45, 45', 45"; 50, 51, 52; 50", 51", 52") are coupled so as to allow a tilt of an angle (α) between the first and second axis (C, D).