Stepped Spacer Vane Ring Assembly for Turbocharger Thermal Warpage
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Solution Overview
Problem
Turbocharger vane ring assemblies face challenges with thermal expansion and deformation, leading to aerodynamic inefficiencies and fastener failure due to the use of traditional fastening methods like studs and bolts, which result in increased clearances and stress, making it difficult to maintain proper alignment and efficiency across varying temperatures.
Innovation Solution
A vane ring assembly using stepped spacers and bores to create a stable structure that decouples the vane rings from thermal warpage, allowing for radial expansion and contraction, and maintaining alignment through a mechanical fit, thereby reducing stress and maintaining aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fastening methods like studs and bolts are used to secure the vane ring assembly, then the assembly can be mechanically secured to the turbine housing, but thermal expansion and deformation cause increased clearances and aerodynamic inefficiencies
Solution Approach 1:
The spacer is divided into multiple sections (first section, second section, third section) with different diameters, allowing each section to serve a specific function: the first section engages with the vane ring, the second section provides clearance for thermal expansion, and the third section engages with the turbine housing. This segmentation enables the assembly to maintain mechanical securing while accommodating thermal deformation.
Solution Approach 2:
The spacer's diameter varies along its length, creating a stepped configuration that changes the dimensional parameters at different locations. This parameter change allows the spacer to maintain a stable reference distance between the vane ring and turbine housing while permitting radial thermal expansion of the turbine housing without transferring stress to the vane ring assembly.
2Stability of the object's composition
If the turbine housing is rigidly connected to the vane ring assembly, then mechanical stability is achieved, but thermal warpage causes stress and potential fastener failure
Solution Approach 1:
The stepped spacer acts as an intermediary element between the turbine housing and the vane ring assembly. It provides a stable mounting reference while isolating the vane ring assembly from thermal stresses generated by the turbine housing. The spacer's stepped design allows it to absorb dimensional changes without transmitting stress to the fasteners, thereby preventing fastener failure while maintaining mechanical stability.
3Temperature
If clearances are increased to accommodate thermal expansion, then thermal deformation is managed, but aerodynamic efficiency is reduced
Solution Approach 1:
The spacer provides clearance accommodation only at specific locations (where the stepped sections create gaps), while maintaining precise alignment and minimal clearances at the mounting interfaces. This localized approach allows thermal expansion to be managed without creating excessive clearances that would compromise aerodynamic efficiency in the critical flow paths.
4Reliability
If multiple fasteners are used to secure the vane ring assembly, then mechanical securing is improved, but assembly complexity and cost increase
Solution Approach 1:
The stepped spacer combines multiple functions into a single component: it provides mechanical mounting, establishes precise spacing, accommodates thermal expansion, and eliminates the need for separate fasteners. By merging these functions into one element, the design reduces assembly complexity and component count while maintaining reliable mechanical securing of the vane ring assembly.
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 reduces the impact of thermal expansion on the vane ring assembly, preventing sticking and maintaining aerodynamic efficiency by allowing for controlled movement and alignment of the vanes, while being cost-effective and facilitating assembly and disassembly.
Implementation Method 1
allowing for radial expansion and contraction, and maintaining alignment through a mechanical fit, thereby reducing stress and maintaining aerodynamic efficiency
Data Source
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AI summary
A vane ring assembly includes a lower vane ring (20), an upper vane ring (30), one or more guide vanes (80) positioned at least partially between the vane rings, and a spacer (50) positioned between the lower and upper vane rings (20, 30) for maintaining a distance between the lower and upper vane rings (20, 30). The spacer has a first end (52) with a first diameter, a second end (54) with a second diameter, and a middle section (56) with a third diameter. The third diameter is larger than the first and second diameters. The first and second ends (52, 54) of the spacer (50) are inserted at least partially into a first counter bore (22) and a second counter bore (32) formed in the lower and upper vane rings (20, 30). A nut (40) and a fastener (42) running through a central through hole (58) of the spacer (50) are used to connect the vane ring assembly to a turbocharger housing. A clearance (c) of greater than e.g. 5% of the fastener diameter is formed between an inside wall (51) of the spacer (50) an outside wall (43) of the metal fastener (42) to offset any thermal expansion or deformation.