Articulated Rotor Transmission Joint With Decoupled Torque Paths
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Solution Overview
Problem
Current transmission joints for tilt-rotor aircrafts with elastomeric bearings face issues of reduced fatigue life, increased cost and weight, and complex maintenance due to overheating and the need for frequent inspection, which complicates the transition between 'airplane' and 'helicopter' configurations.
Innovation Solution
A transmission joint utilizing a constant velocity joint design with rollers and chambers, featuring a combination of steel and elastomeric materials for damping, and a spherical hinge mechanism that allows independent transmission of torque and aerodynamic forces, reducing the reliance on elastomeric components and simplifying maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elastomeric bearings are used to transmit both torque and aerodynamic forces, then the transmission joint can handle combined loads, but the fatigue life is reduced and weight increases
Solution Approach 1:
The invention separates the transmission functions into distinct components: steel bearings handle torque transmission while elastomeric elements handle aerodynamic forces. This segmentation allows each material to be optimized for its specific function, preventing the fatigue issues that arise when elastomeric bearings must handle both load types simultaneously.
Solution Approach 2:
The invention combines steel bearing structures with elastomeric elements in a unified transmission joint design. The steel components provide durable torque transmission paths while elastomeric elements provide force transmission paths, creating a hybrid system that leverages the advantages of both materials without the drawbacks of using either alone.
2Adaptability or versatility
If elastomeric bearings are used for combined torque and force transmission, then the joint can accommodate hub oscillations, but the cost increases
Solution Approach 1:
The transmission joint is segmented into separate torque transmission paths (using steel bearings) and force transmission paths (using elastomeric elements). This allows each path to be designed and manufactured independently with appropriate materials, reducing overall cost compared to using expensive elastomeric bearings for both functions.
Solution Approach 2:
Different local regions of the transmission joint use different materials optimized for their specific functions: steel for high-strength torque transmission areas and elastomeric materials for force transmission areas requiring damping and oscillation accommodation. This localized material selection reduces overall manufacturing cost while maintaining performance.
3Device complexity
If elastomeric bearings are used to transmit both torque and aerodynamic forces, then the joint design is simplified, but the weight increases
Solution Approach 1:
The transmission joint is divided into separate torque and force transmission paths with dedicated components for each function. This segmentation allows for more efficient material usage and weight optimization compared to a monolithic elastomeric bearing design that would require excessive material to handle both load types simultaneously.
Solution Approach 2:
The invention replaces the mechanical elastomeric bearing system with a hybrid system using steel bearings for torque transmission. This substitution eliminates the need for heavy elastomeric material while maintaining the ability to transmit both torque and forces through different paths.
4Stability of the object's composition
If elastomeric material components are used, then the joint can dampen vibrations, but overheating occurs during prolonged flight
Solution Approach 1:
The vibration damping function is segmented from the torque transmission function. Elastomeric elements are used only for force transmission and damping where needed, while steel bearings handle torque transmission. This segmentation reduces the total volume of elastomeric material, thereby reducing heat generation and overheating risks during prolonged flight.
Solution Approach 2:
The invention extracts the torque transmission function from the elastomeric material components and assigns it to steel bearings. This extraction removes the primary source of heat generation from the elastomeric elements, allowing them to retain their vibration damping benefits without the harmful thermal effects of prolonged torque transmission.
5Device complexity
If the transmission joint uses current elastomeric bearing design, then torque and forces can be transmitted through a single mechanism, but maintenance becomes complex
Solution Approach 1:
The transmission joint is segmented into separate torque and force transmission paths with distinct components. This segmentation allows for independent inspection, maintenance, and replacement of each path's components, simplifying maintenance procedures compared to a single integrated elastomeric bearing system where all functions are coupled.
Solution Approach 2:
Different components are designed with different material properties and maintenance requirements: steel bearings for torque transmission that can be easily inspected and replaced, and elastomeric elements for force transmission that can be independently maintained. This localized design approach simplifies overall maintenance by allowing targeted repairs without affecting the entire transmission joint.
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 solution enhances the fatigue life, reduces weight and cost, and simplifies maintenance by decoupling torque and force transmission paths, preventing contamination and allowing for easier replacement of components, while maintaining efficient operation across configuration transitions.
Implementation Method 1
a steel bearing, arranged substantially circumferentially to the third axis and configured to transmit the torque from the control shaft to the hub
Implementation Method 2
an elastomeric element, arranged substantially circumferentially to the third axis and configured to transmit the aerodynamic forces from the hub to the control shaft
Implementation Method 3
The articulated transmission joint is designed to allow the fourth axis of the hub of the tilt-rotor aircraft to oscillate in relation to the third axis of the control shaft for a given maximum angle
Data Source
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AI summary
An articulated transmission joint (20; 20'; 20") for connecting a drive 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).