TiAl Turbocharger Impeller Grooves for Blade Edge Chip Resistance
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Solution Overview
Problem
TiAl alloy impellers face issues with chipping at the outer edge due to high strength and high melting point, leading to decreased performance when used in turbochargers, and increasing the thickness to prevent chipping results in reduced efficiency.
Innovation Solution
The TiAl alloy impeller features processed surfaces with holes or grooves that retain foreign matter, satisfying specific depth-to-curvature radius ratios, enhancing smoothness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the outer edge of the blade is increased to suppress chipping, then reliability is improved, but performance (exhaust efficiency, fuel efficiency) is decreased
Solution Approach 1:
The processed surface is designed with holes having specific depth-to-curvature radius ratios (Dh≤2×Rh) to create a porous structure that retains foreign matter. This porous configuration prevents chipping by providing mechanical interlocking for foreign particles while maintaining the thin outer edge thickness needed for high exhaust efficiency.
Solution Approach 2:
The invention applies different surface characteristics to different regions: the outer edge maintains thin thickness for performance while the processed surface includes localized holes for chip resistance. The grooves are specifically positioned at the outer edge where foreign matter accumulation is most critical, providing localized reinforcement without compromising overall blade thinness.
2Reliability
If the thickness of the outer edge of the blade is increased to suppress chipping, then reliability is improved, but performance (exhaust efficiency, fuel efficiency) is decreased
Solution Approach 1:
The processed surface is designed with holes having specific depth-to-curvature radius ratios (Dh≤2×Rh) to create a porous structure that retains foreign matter. This porous configuration prevents chipping by providing mechanical interlocking for foreign particles while maintaining the thin outer edge thickness needed for high exhaust efficiency.
Solution Approach 2:
The invention applies different surface characteristics to different regions: the outer edge maintains thin thickness for performance while the processed surface includes localized holes for chip resistance. The grooves are specifically positioned at the outer edge where foreign matter accumulation is most critical, providing localized reinforcement without compromising overall blade thinness.
3Strength
If TiAl alloy is used to manufacture impeller with required blade shape, then strength is improved, but chipping occurs at outer edge due to high melting point and high viscosity
Solution Approach 1:
The processed surface is designed with holes having specific depth-to-curvature radius ratios (Dh≤2×Rh) to create a porous structure that retains foreign matter. This porous configuration prevents chipping by providing mechanical interlocking for foreign particles while maintaining the thin outer edge thickness needed for high exhaust efficiency.
Solution Approach 2:
The invention converts the harmful effect of high viscosity during casting into a beneficial outcome by controlling the solidification process to create a lamellar structure with alternating α2 and γ layers. This structure provides inherent strength and chip resistance without requiring increased thickness.
Data Source
AI summary
A TiAl alloy impeller is composed of a TiAl alloy and is mountable on a vehicle turbocharger. The TiAl alloy has a lamellar structure in which an α2 layer containing Ti3Al and a γ layer containing TiAl are alternately stacked. The TiAl alloy impeller includes a shaft portion and blades, each of the blades includes an outer edge, and a region of each of the blades including the outer edge has a processed surface. The processed surface is provided with one or more grooves. At least one of the grooves satisfies a relation of Dg>2×Rg or Dg>Wg, where Dg represents a depth of the groove and Rg represents a curvature radius of the groove at a bottom surface of the groove or Wg represents a width of the groove. Thus, a TiAl alloy impeller having high performance as an impeller is provided.