Multi-Axis Joint for Gas Turbine Vane Arm Positioning
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Solution Overview
Problem
Current gas turbine engine systems face inefficiencies due to over-constrained loading conditions between vane arm pins and bushings, leading to increased reaction loads and inaccuracies in variable vane orientation, which hinder engine performance.
Innovation Solution
The introduction of a multi-axis joint feature allowing the vane arm to pivot about a second rotational axis relative to the synchronizing ring, reducing bending/twisting moments and improving positioning accuracy by providing additional degrees of freedom, thereby reducing the size and weight of the actuator required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional synchronizing ring design with fixed vane arm connections is used, then the structure is simple, but over-constrained loading conditions create large reaction loads and positioning inaccuracies
Solution Approach 1:
The patent applies the dynamics principle by transforming the rigid fixed connection between vane arms and synchronizing ring into a dynamic multi-axis joint system. The first trunnion allows rotation about a first axis, while the second trunnion enables rotation about a second axis perpendicular to the first. This dynamic configuration allows the joint to adapt its orientation during operation, accommodating movement variations and reducing over-constraint while maintaining reliable positioning accuracy.
Solution Approach 2:
The patent implements dimensionality change by adding a second rotational axis (second trunnion) that is perpendicular to the first rotational axis (first trunnion). This transforms the single-degree-of-freedom connection into a two-degree-of-freedom joint, providing additional movement freedom in a new dimension. The second axis allows the joint to compensate for misalignments and reduce reaction loads while improving positioning reliability.
2Strength
If over-constrained loading conditions are maintained, then the structure is rigid, but large reaction loads require larger and heavier actuators
Solution Approach 1:
The multi-axis joint system transforms the rigid over-constrained structure into a dynamic mechanism that maintains structural strength through controlled degrees of freedom. The first and second trunnions work together to provide necessary rigidity for strength while allowing movement freedom that reduces reaction loads, thereby enabling the use of lighter actuators without compromising structural integrity.
Solution Approach 2:
The multi-axis joint acts as an intermediary mechanism between the synchronizing ring and vane arms, mediating the transmission of forces and movements. By introducing this intermediate joint system with multiple rotational axes, the patent reduces the direct over-constrained loading that would otherwise require heavy-duty actuators, while still maintaining the necessary structural strength through the trunnion-bushing configuration.
3Manufacturing precision
If fixed-axis connections are used between vane arms and synchronizing ring, then manufacturing is simpler, but positioning accuracy of variable vanes deteriorates
Solution Approach 1:
The patent applies dynamics by replacing fixed-axis connections with a multi-axis joint system that can adapt its orientation dynamically. The first and second trunnions enable the joint to accommodate movement variations and maintain precise vane orientation throughout the range of motion, improving manufacturing precision through dynamic adaptation rather than relying solely on tight fixed tolerances.
Solution Approach 2:
The joint is segmented into distinct functional components: the first trunnion for rotation about the first axis, the second trunnion for rotation about the second axis, and the associated bushings. This segmentation allows each component to be manufactured and assembled separately with standard tolerances, reducing the overall manufacturing complexity while achieving high positioning accuracy through the coordinated action of the segmented joint system.
Data Source
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AI summary
An assembly includes a synchronizing ring, a vane arm, and a multi-axis joint. The multi-axis joint connects the synchronizing ring to the vane arm and provides the vane arm with movement about a first pivot axis and a second pivot axis.