Turbine Housing Scroll Flow Path Roughness Reduction
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Solution Overview
Problem
Small turbine housings for turbochargers have higher surface roughness and flow resistance due to casting limitations, leading to inefficiencies and performance variations.
Innovation Solution
A turbine housing design with a scroll part, exhaust duct part, and shroud part, featuring a larger opening radius and processed flow-path surfaces to reduce roughness and flow resistance, along with separate plate members and tongue portions to minimize interference and thickness, facilitating easier processing and reduced flow strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small turbine housing is produced by casting, then the turbocharger size is reduced, but the surface roughness inside the housing increases and flow resistance of exhaust gas increases
Solution Approach 1:
The patent applies preliminary action by forming a smooth flow-path surface on the inner peripheral side of the scroll flow path before the casting process completes. A smooth section is created in advance in the region where exhaust gas flows at high speed, preventing the formation of rough casting surfaces in critical flow areas. This preliminary smoothing action reduces flow resistance while maintaining the small turbocharger size.
Solution Approach 2:
The patent applies local quality by providing a smooth flow-path surface only in the specific region A on the inner peripheral side of the scroll flow path where exhaust gas flows at high speed, rather than smoothing the entire housing. This localized smoothing approach reduces flow resistance where it matters most while minimizing the complexity of the overall manufacturing process.
2Volume of moving object
If a small turbine housing is produced by casting, then the turbocharger size is reduced, but casting errors increase and performance variation between products increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the smooth flow-path surface in the critical scroll flow path region before final casting completion. This preliminary action ensures consistent flow characteristics and reduces performance variation between products by establishing a standardized smooth surface in the most critical flow area.
3Object-generated harmful factors
If the opening part radius is increased to allow post-casting processing, then the flow-path surface roughness can be reduced, but the turbine housing structure becomes more complex
Solution Approach 1:
The patent applies preliminary action by incorporating the smooth flow-path surface formation as an integral part of the casting process itself, rather than requiring separate post-casting processing steps. The smooth section is formed in advance during casting, eliminating the need for additional complex processing equipment or multiple manufacturing steps.
Solution Approach 2:
The patent merges the smooth flow-path surface formation with the casting process by creating region A as an integrated feature of the scroll flow path. This combining of functions allows the smooth surface to be achieved without adding separate processing steps or increasing structural complexity.
Data Source
AI summary
An object is to provide a turbine housing with a simple structure whereby it is possible to reduce flow resistance of exhaust gas and improve efficiency of a turbocharger. A turbine housing made by casting has an opening part formed on a hub side of a scroll part, the opening part having a radius R2 which satisfies a relationship R1<R2, provided that R1 is a radial directional distance from an axis of a turbine wheel to a tip of a shroud part and R2 is a radial directional distance from the axis to an inner peripheral edge of a hub-side wall surface of the scroll part. A roughness of a flow-path surface in a region A is smaller than in a region B, provided that the region A is a predetermined range from the tip of the shroud part and the region B is a predetermined range adjacent to the region A, among flow-path surfaces of the shroud part and the scroll part facing a scroll flow path on an outer side, in a radial direction, of the tip of the shroud part.