Turbine Rotor Cover Plate Lock Assembly
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Solution Overview
Problem
Existing anti-rotation features in gas turbine engine turbine sections face challenges due to temperature variations and circumferential forces, requiring cost-effective solutions that maintain performance in the operational environment.
Innovation Solution
A rotor assembly and method for assembling a cover plate to a turbine rotor using a lock assembly with a key and flange mechanism that provides an interference fit and prevents rotation, utilizing a threaded bolt and lock configuration to secure the cover plate in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional anti-rotation features are used in turbine rotor covers, then the cover can be secured in place, but the features experience temperature variations and circumferential forces that compromise reliability
Solution Approach 1:
The lock assembly utilizes thermal expansion parameter changes by incorporating a lock slot with a specific geometric configuration that allows the lock to expand and contract with the rotor cover during temperature cycles, maintaining engagement without failing under thermal stress
Solution Approach 2:
The anti-rotation function is divided into multiple locking positions around the circumference, with the lock assembly capable of engaging at different locations depending on the operational state, distributing the circumferential forces across multiple contact points
2Strength
If the cover is heated during assembly and then cooled to provide interference fit, then secure attachment is achieved, but the anti-rotation features are subjected to thermal stress
Solution Approach 1:
The lock slot is designed with clearance and geometric features that accommodate thermal expansion during assembly, allowing the lock assembly to be installed before the final thermal stress state is achieved, with the slot geometry providing cushioning against thermal shock
3Reliability
If anti-rotation features are designed to withstand operational forces, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The lock assembly is designed to self-lock through the interaction between the lock protrusion and lock slot geometry, eliminating the need for additional fasteners or complex mechanisms, thereby reducing manufacturing cost while maintaining operational reliability
Solution Approach 2:
The lock slot features an asymmetric geometric configuration that provides unidirectional locking action, allowing the lock to engage securely in one direction while accommodating thermal expansion and operational forces, achieving reliability without requiring symmetric, overly complex designs
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 effectively secures the cover plate to the rotor, preventing rotation and maintaining performance under operational conditions, while ensuring a stable and cost-effective design.
Implementation Method 1
The cover is typically heated during assembly, and then cooled once installed to provide an interference fit
Implementation Method 2
The anti-rotation features experience temperature variations along with circumferential forces during operation
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
A rotor assembly for a gas turbine engine includes a rotor configured for rotation about an engine axis, the rotor including an aft surface including a rotor slot and a cover plate attached to the aft surface of the rotor, the cover plate including a tab received within the rotor slot and a cover plate slot aligned with the rotor slot. A lock assembly disposed within the rotor slot holds a position of the cover plate relative to the rotor. The lock assembly includes a key portion conforming to the rotor slot, a lock portion engageable with a surface of the rotor slot and a threaded member for holding the lock assembly within the rotor slot.