Bushing for Variable Pitch Vane Pivot in Turbomachine
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Solution Overview
Problem
Existing mountings for blade guide pivots in turbomachines fail to maintain optimal centering, especially when materials with different coefficients of thermal expansion are used, leading to reduced effectiveness over the operating phases of the turbomachine.
Innovation Solution
A sleeve with a biconical connection, featuring conical collars at both ends, ensures permanent centering by compensating for diameter expansion differences through height expansion, and includes anti-rotation means to prevent rotation, allowing for secure fitting regardless of material differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mountings with simple cylindrical sockets are used, then the device complexity is low and ease of manufacture is high, but the centering quality deteriorates due to differential thermal expansion between materials
Solution Approach 1:
The patent applies conical surfaces (curved geometry) to the socket structure, replacing simple cylindrical geometry with biconical geometry. The conical collars create curved contact surfaces that provide self-centering action and compensate for thermal expansion effects, thereby maintaining centering quality while managing the complexity through geometric design
Solution Approach 2:
The patent changes the geometric parameters of the socket by introducing conical surfaces with specific angles. The conical collars have predetermined angles that allow the socket to accommodate differential thermal expansion while maintaining proper centering, transforming the static cylindrical geometry into a dynamic conical geometry that adapts to thermal conditions
2Adaptability or versatility
If materials with different coefficients of thermal expansion are used for the socket and inner ring, then the adaptability to different operating conditions is improved, but the centering stability deteriorates during thermal cycles
Solution Approach 1:
The patent converts the harmful effect of differential thermal expansion into a beneficial self-compensating mechanism. The conical geometry is designed so that thermal expansion differences between materials actually help maintain centering by allowing the socket to adjust its position along the conical surfaces, transforming the instability problem into a self-correcting feature
Solution Approach 2:
The patent introduces dynamic adaptability to the socket structure through conical surfaces that allow for thermal movement. Rather than rigidly fixing the socket position, the conical geometry enables controlled movement and adjustment during thermal cycles, maintaining stability through dynamic adaptation rather than static rigidity
3Reliability
If anti-rotation means are added to the socket, then the reliability of blade alignment is improved, but the ease of manufacture decreases
Solution Approach 1:
The conical surfaces serve dual functions: providing the biconical connection for thermal compensation and acting as anti-rotation features. The angled conical surfaces prevent rotational movement of the socket relative to the inner ring, eliminating the need for separate anti-rotation components and maintaining ease of manufacture while ensuring reliable blade alignment
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 biconical connection maintains consistent centering quality and anti-rotation features ensure stability, even with varying thermal expansion, thus maintaining optimal blade alignment and reducing wear throughout the turbomachine's operation.
Implementation Method 1
any movement in difference in expansion in diameter of the ring relative to the sleeve is compensated by the difference in expansion in height of the ring
Data Source
Figure 1
Figure 2~4
Figure 3A~3B
AI summary
Bushing for a variable-angle blade pivot for a turbomachine, the bushing (18) being intended to be mounted in a recess (20) of a ring (22) of the turbomachine having a shape substantially complementary to that of the bushing. The bushing comprises a substantially tubular body (24) with a longitudinal axis provided at one end with a first conical flange (26) and at the opposite end with a second conical flange (28), the conical surfaces defined by the first and second flanges (26, 28) being arranged opposite each other.