Variable Geometry Turbine Linkage Mechanism for Thermal Expansion
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Solution Overview
Problem
Variable geometry turbines face challenges in accommodating differential thermal expansion between components, leading to mechanical distortion and performance issues due to the high operating temperatures and corrosive conditions, which existing linkage mechanisms struggle to address effectively.
Innovation Solution
A linkage mechanism with a radially extending flange and a retaining member that accommodates differential expansion through a clearance, allowing for secure connection and positioning of the annular wall member while preventing excessive tilting and maintaining robustness, without the need for costly high-performance materials or precise bores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rods are securely fixed to the nozzle ring, then the connection between components is strong and reliable, but mechanical distortion occurs due to differential thermal expansion
Solution Approach 1:
The patent changes the connection parameter from rigid fixed to flexible jointed connection, allowing the linkage mechanism to accommodate differential thermal expansion through controlled movement rather than mechanical distortion
Solution Approach 2:
The linkage mechanism introduces dynamic adaptability to the connection system, enabling it to adjust and accommodate the differential expansion between the nozzle ring and rods through controlled movement of the linkage components
2Adaptability or versatility
If a linkage mechanism with limited relative movement is used, then differential expansion is accommodated, but the mechanism becomes complex and difficult to manufacture
Solution Approach 1:
The linkage mechanism is segmented into distinct components (linkage body, pivot, stop, washers, rivets) that can be manufactured separately using standard machining operations, simplifying the overall manufacturing process while maintaining the required adaptability
Solution Approach 2:
The linkage mechanism acts as an intermediary between the rods and nozzle ring, providing a simple yet effective means to accommodate differential expansion through a straightforward mechanical connection that avoids complex manufacturing requirements
3Adaptability or versatility
If the linkage mechanism allows excessive movement, then differential expansion is accommodated, but the nozzle ring tilts excessively affecting operating clearances
Solution Approach 1:
The linkage mechanism provides controlled dynamic movement that accommodates differential expansion while maintaining constraints to prevent excessive tilting, achieving a balance between adaptability and positioning precision
Solution Approach 2:
The linkage mechanism changes the movement parameter from unrestricted to controlled, allowing sufficient movement for thermal expansion accommodation while maintaining the nozzle ring within acceptable positioning tolerances
4Reliability
If costly high-performance materials and precise bores are used, then the linkage mechanism is robust and reliable, but manufacturing costs increase significantly
Solution Approach 1:
The linkage mechanism uses inexpensive, readily available materials (steel, aluminum, brass) and standard machining operations instead of costly high-performance materials and precision grinding, achieving sufficient reliability for the application at lower cost
Solution Approach 2:
The patent uses conventional materials and manufacturing methods that replicate the functional requirements of expensive solutions, achieving acceptable reliability through proven, cost-effective approaches rather than advanced materials and processes
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 accommodates differential expansion, ensuring reliable operation and positioning of the nozzle ring, reducing manufacturing costs and improving durability by eliminating the need for precise bores and costly materials, while maintaining performance across varying temperatures and conditions.
Implementation Method 1
different components exhibit different rates of thermally induced expansion or contraction
Data Source
AI summary
A variable geometry turbine comprises: a turbine wheel in a housing assembly defining a radial gas flow inlet passage; an annular wall member which is displaceable to control gas flow through the inlet passage; and a linkage mechanism comprising at least one actuating member operably connected to the annular wall member to control displacement of the wall member. The actuating member has a terminal portion defining a radially extending flange and extends in a direction substantially parallel to the turbine axis through an aperture defined by a retaining member to locate the radially extending flange in between said retaining member and annular wall member. The terminal portion is contacted by the retaining member to connect the actuating member to the annular wall member. The aperture defines a clearance to accommodate displacement of the retaining member relative to the actuating member.