Turbine Wastegate Toroidal Plug Sealing
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Solution Overview
Problem
Turbine wastegates in internal combustion engines face challenges in maintaining effective sealing and controllability due to mechanical stresses and misalignment issues, leading to exhaust leakage and reliability concerns, especially under high operational temperatures and varying load conditions.
Innovation Solution
The design incorporates a wastegate arm and plug assembly with a toroidal and conical profile, featuring two plug portions that provide clearances and alignment to ensure effective sealing and control, even under misalignment conditions, utilizing a spherical cap shape to enhance operational dynamics and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wastegate plug is designed with sufficient sealing force to prevent exhaust leakage, then sealing efficiency is improved, but mechanical stresses on kinematic components increase leading to oversized component design
Solution Approach 1:
The wastegate plug is designed with a spherical sealing surface that contacts a corresponding spherical seat. This curved geometry distributes the sealing force uniformly across the contact area, reducing peak stresses on the plug and seat components while maintaining effective sealing. The spherical configuration allows the plug to self-center and evenly distribute loads during operation, preventing stress concentration that would occur with flat or angular contact surfaces.
2Strength
If wastegate components are oversized to meet reliability levels under high mechanical stresses, then component strength is improved, but device complexity and size increase
Solution Approach 1:
The spherical geometry of the plug and seat creates a point or line contact that concentrates sealing force efficiently, allowing smaller component dimensions to achieve the required sealing performance. The curved surfaces naturally distribute stresses during rotation and operation, enabling the use of smaller, lighter components compared to flat-surface designs that would require larger safety margins and oversized dimensions to handle the same loads.
Solution Approach 2:
The invention changes the geometric parameters of the sealing surfaces from flat or angular configurations to spherical profiles. This parameter change fundamentally alters the stress distribution characteristics, allowing the system to achieve high reliability with smaller component sizes. The spherical geometry transforms the stress field from concentrated edge loads to distributed radial loads, reducing the required component cross-sections and overall size.
3Ease of manufacture
If a flat disk shaped plug is used to seal against a flat seat, then manufacturing simplicity is improved, but sealing effectiveness deteriorates under misalignment and high temperature conditions
Solution Approach 1:
The spherical sealing surfaces provide self-aligning characteristics that compensate for misalignment between the plug and seat. The curved geometry allows the plug to rotate and find its correct positioning, ensuring consistent contact with the seat even when initial alignment is imperfect. This self-correcting mechanism maintains sealing effectiveness under thermal expansion and mechanical misalignment conditions that would cause flat-surface seals to fail.
Data Source
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AI summary
An assembly can include a turbine housing that includes a bore, a wastegate seat and two wastegate passages that extend to the wastegate seat; a rotatable wastegate shaft configured for receipt by the bore; a wastegate arm extending from the wastegate shaft; and a wastegate plug extending from the wastegate arm where the wastegate plug comprises a profile defined in part by a portion of a torus, for contacting the wastegate seat in a closed state, and defined in part by two plug portions, for defining clearances with respect to the wastegate seat in an open state. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.