Compressor Wheel Hub Back Surface Geometry for Stress Reduction
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Solution Overview
Problem
The existing compressor wheel mounting structures face issues with balance changes due to high centrifugal stress and temperature, leading to potential disengagement and plastic deformation during supercharger operation, which can result in balance deterioration.
Innovation Solution
A compressor wheel mounting structure with a hub having a through-hole and blades, where the rotary shaft is interference-fitted with the hub through a sleeve, featuring a specific back surface geometry with a flat contact surface and recessed areas to reduce centrifugal stress and prevent plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If two large-diameter portions are formed across a small-diameter portion in a portion inserted into the through-hole of the rotary shaft, then the axial center of the compressor wheel is stabilized, but the fitting portion on the back surface side experiences high centrifugal stress and temperature leading to disengagement and plastic deformation
Solution Approach 1:
The invention applies different geometric characteristics to different regions of the back surface. The first region has a gentle slope (inclination angle ≤45°) to reduce stress concentration, while the second region has a steeper slope (inclination angle >45°) for structural support. This local differentiation allows the fitting portion to maintain axial center stability while avoiding excessive centrifugal stress and plastic deformation in the high-stress back surface area.
2Ease of operation
If the fitting portion is designed to accommodate the through-hole, then the compressor wheel can be mounted on the rotary shaft, but the fitting portion may be disengaged during operation due to high centrifugal stress and temperature
Solution Approach 1:
The invention introduces curved surfaces with specific inclination angles in the recessed portion of the back surface. The curved transition regions with controlled inclination angles (≤45° in the first region, >45° in the second region) distribute stresses more evenly compared to sharp corners or flat transitions, preventing stress concentration that would lead to disengagement during high-speed rotation and thermal conditions.
3Strength
If the fitting portion is subjected to high centrifugal stress during operation, then the compressor wheel can be securely mounted, but the fitting portion undergoes plastic deformation leading to balance deterioration
Solution Approach 1:
The invention changes the geometric parameters of the back surface by defining specific inclination angle ranges (≤45° for the first region, >45° for the second region) and positioning the curved surface at specific locations. These parameter optimizations reduce stress concentration factors in the fitting portion, allowing the compressor wheel to maintain secure mounting through interference fit while preventing plastic deformation that would compromise balance precision during high-speed operation.
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 reduces the risk of balance changes in the compressor wheel by minimizing centrifugal stress and preventing plastic deformation, ensuring stable operation and stopping conditions.
Implementation Method 1
The outer peripheral surface of the rotary shaft and the through-hole of the hub are joined through interference-fit
Data Source
AI summary
The back surface of a hub of a compressor wheel mounting structure according to the present invention comprises a recessed surface which is formed from the outer peripheral end of a flat surface to the outer peripheral edge of the back surface. The recessed surface includes: a first line segment region which extends from the outer peripheral end of the flat surface, which is one end, and toward the other side in the axial direction and in which a curved line having an inclination angle θ1 that is not more than 45 degrees with respect to the axial direction and that becomes greater toward d said other side in the axial direction is at least formed at a position including the other end of the first line segment region; and a second line segment region which extends from said other end of the first line segment region and toward the outer peripheral side in the radial direction and in which a curved line having an inclination angle θ2 that is 45-90 degrees with respect to the axial direction and that becomes greater toward the outer peripheral side is at least formed at a position including a connection part with the first line segment region. Said other end of the first line segment region is provided at a position more to the inner peripheral side than ½ the outer dimension of the back surface of the hub in a direction perpendicular to the axial direction.