Turbocharger Impeller Hub Segmentation for Stress Management
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Solution Overview
Problem
Modern impellers for exhaust gas turbochargers face high tensile stresses due to centrifugal force, limiting their service life and performance, especially at the transition between the hub main body and blades, and current designs are not optimally configured to manage these stresses without increasing weight.
Innovation Solution
The hub main body is redesigned as a polygon with tilted segments or an undulating surface to absorb stresses effectively, allowing for a lighter configuration with local material reinforcement at critical areas, avoiding kinks and stress intensifiers, and featuring a notch-free transition to enhance performance and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the hub main body is configured as a continuously round rotational body, then the manufacturing is simple, but the load absorption capability at the transition between blade and hub is insufficient
Solution Approach 1:
The hub main body is divided into multiple segments (e.g., five segments) that are tilted with respect to one another, creating a polygonal configuration. This segmentation allows each segment to be optimized for load absorption while maintaining manufacturing feasibility through modular construction approaches.
Solution Approach 2:
The hub main body features local variations in geometry, including tilted segments and undulations in the circumferential direction, specifically positioned to absorb tensile stresses at critical transition regions. These local modifications concentrate material and geometric features where stresses are highest, without requiring complete redesign of the entire hub.
2Strength
If the radius at the transition between blade and hub main body is increased, then the load absorption is improved, but the weight of the impeller increases
Solution Approach 1:
Instead of uniformly increasing the radius throughout the hub, the invention applies local geometric modifications including tilted segments and circumferential undulations specifically at the transition regions where tensile stresses occur. This localized approach provides the necessary load absorption capability while minimizing unnecessary material addition and weight increase.
Solution Approach 2:
The invention employs curved transitions and undulations in the hub main body geometry to smoothly distribute stresses. The rounded transitions between segments and blades, along with circumferential undulations, create favorable stress distribution patterns that reduce stress concentrations without requiring excessive material thickness.
3Power
If the backward curvature of blades is increased, then the centrifugal force utilization is improved, but the tensile stresses at the attachment region increase
Solution Approach 1:
The hub main body is segmented into multiple tilted segments that work together to distribute the tensile stresses generated by blade backward curvature. Each segment absorbs a portion of the stress, and the segmented structure allows for better stress distribution across the attachment region compared to a solid continuous hub.
Solution Approach 2:
The segments are tilted with respect to one another in an asymmetric arrangement, creating a polygonal configuration that optimizes stress distribution. This asymmetric geometry allows the hub to better accommodate the directional stresses induced by backward curved blades while maintaining structural integrity.
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 design optimizes load absorption and reduces weight, improving the impeller's performance and service life while preventing damage to the compressor housing, achieving a longer operational lifespan and better response behavior for the exhaust gas turbocharger.
Implementation Method 1
Under the influence of the centrifugal force on a suction side in the attachment region of the blades to the hub main body, said backward curvature leads to high tensile stresses
Data Source
AI summary
An impeller for an exhaust gas turbocharger may include a hub main body and blades arranged thereon. The hub main body may be configured as a polygon with a number of segments that may be tilted with respect to one another, the number of the segments corresponding to a number of the blades. Alternatively, the hub main body may have a main surface that faces the blades and undulates in a circumferential direction, a number of the undulations corresponding to the number of the blades.