Variable Nozzle Seal Flange Occluding End Gaps
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Solution Overview
Problem
The existing variable-geometry turbocharger systems face inefficiencies due to insufficient prevention of exhaust gas leakage through the end gaps of the seal rings, which hinders the improvement of turbine efficiency.
Innovation Solution
A variable nozzle unit is designed with a seal flange on the upstream-side seal ring that partially occludes the end gap of the downstream-side seal ring, reducing the leakage area and enhancing sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple seal rings are provided to suppress leakage of exhaust gas, then sealing performance is improved, but exhaust gas still leaks through the end gaps of the seal rings
Solution Approach 1:
The invention adds a new dimensional element by introducing a seal flange that extends in the axial direction from the seal ring. This axial extension creates an additional sealing surface that blocks the end gap leakage path, transforming the sealing approach from radial contact only to a combination of radial and axial sealing.
Solution Approach 2:
The sealing function is divided into multiple segments: the seal ring provides radial sealing contact with the turbine housing, while the seal flange provides axial sealing by blocking the end gap. This segmentation of sealing functions allows each component to address specific leakage paths independently.
2Ease of manufacture
If the end gap of the downstream-side seal ring is left open, then assembly and manufacturing are simplified, but exhaust gas leaks through this gap reducing turbine efficiency
Solution Approach 1:
The seal flange acts as an intermediary element that blocks the end gap without requiring complex assembly procedures. Instead of making the end gap tighter which would complicate assembly, the flange provides a simple axial barrier that prevents gas leakage while maintaining easy assembly characteristics.
3Reliability
If multiple seal rings with displaced end gaps are used, then some leakage paths are blocked, but the downstream-side seal ring's end gap remains as a final leakage area
Solution Approach 1:
The seal flange introduces axial dimension sealing to complement the radial sealing of the seal rings. By extending axially to block the end gap, it eliminates the final leakage area that remained despite the displaced end gap configuration of multiple seal rings.
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
This configuration effectively prevents exhaust gas leakage, thereby improving the turbine efficiency of the variable-geometry turbocharger by ensuring a more secure seal during operation.
Implementation Method 1
multiple seal rings provided in pressure-contact by their own elastic forces with an inner peripheral surface of the step portion
Data Source
AI summary
An annular seal flange is formed at an inner peripheral edge portion of an upstream-side seal ring. The seal flange projects in a downstream direction. When seal rings are viewed from radially inside, the seal flange of the upstream-side seal ring is designed to at least partially occlude an end gap of the downstream-side (the most downstream-side) seal ring.