Variable Pitch Fan Remote Counterweight Phase Control
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Solution Overview
Problem
Current variable pitch fan assemblies in turbomachines face challenges in maintaining efficient and reliable operation due to limitations in the control and synchronization of counterweight systems, which can lead to inefficiencies and potential failures during pitch angle adjustments.
Innovation Solution
The implementation of a remote counterweight phase control mechanism using a plurality of trunnions, counterweight assemblies, and unison ring gears that engage with counterweight gears, ensuring synchronized rotation and providing redundancy to maintain phase synchronization and safety in case of actuation failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a counterweight system is used to control fan blade pitch angles, then the efficiency of the variable pitch fan assembly is improved, but the reliability is worsened due to potential actuation failures and phase misalignment
Solution Approach 1:
The counterweight phase control mechanism is designed to proactively maintain proper phasing of counterweights relative to fan blades before failures occur. The unison ring gear and gear train establish predetermined phase relationships that automatically correct or prevent phase misalignment, addressing potential actuation failures before they compromise reliability.
Solution Approach 2:
The gear train mechanism provides mechanical feedback by coupling the rotation of one counterweight to others through the unison ring gear. This ensures that if one counterweight deviates from its proper phase, the gear engagement forces it back into synchronization, creating a self-correcting system that maintains reliability.
2Measurement precision
If multiple counterweight assemblies are used to control pitch angles, then the control precision is improved, but the device complexity is worsened
Solution Approach 1:
Multiple counterweight assemblies are merged into a unified system through the unison ring gear and gear train mechanism. This single integrated structure controls the phase of all counterweights simultaneously, achieving precise control without proportionally increasing complexity. The shared gear train provides synchronized control across all assemblies.
Solution Approach 2:
The unison ring gear serves multiple functions: it couples counterweight gears together, maintains phase synchronization, and provides a mechanical feedback path. This multi-functionality allows precise control of multiple counterweights through a single universal mechanism rather than requiring separate control systems for each assembly.
3Reliability
If remote counterweight phase control is implemented, then the reliability is improved through redundancy, but the device complexity is worsened
Solution Approach 1:
The mechanism uses counterweights positioned to create balancing forces that compensate for potential actuation failures. The remote phase control system ensures that counterweights remain properly phased to provide continuous balancing, maintaining reliability even when individual actuators fail by using the gear train to enforce proper phasing relationships.
Data Source
AI summary
A variable pitch fan assembly includes a plurality of rotating trunnion assemblies, a plurality of counterweight assemblies, a first unison ring gear engaged with the trunnion assemblies, and a second unison ring member that restricts out of synch movement of the counterweights relative to each other.