Tapered Rotor Assemblies for Supercharger Thermal Expansion
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Solution Overview
Problem
The efficiency of supercharger assemblies is compromised by thermal expansion, leading to increased likelihood of 'scuff' at the ends of counter-rotating rotors due to uneven clearances, which affects the flow of intake air and overall performance.
Innovation Solution
The rotors are designed with a tapering shape, where the outer radius decreases from the inlet end to the outlet end, ensuring that clearances between rotor tips and the housing remain consistent, minimizing the risk of scuff and optimizing air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotors are designed with uniform outer radius, then the manufacturing is simpler, but thermal expansion causes uneven clearances leading to scuff at the rotor ends
Solution Approach 1:
The rotor is designed with a tapered outer radius where the distance from the rotational axis to the outer surface varies along the longitudinal axis. Specifically, the outer radius at the inlet end is greater than at the outlet end, creating different clearance characteristics at different locations to compensate for thermal expansion effects during operation.
2Reliability
If the outer radius tapers from inlet end to outlet end, then thermal expansion effects are compensated and scuff is prevented, but the rotor geometry becomes more complex
Solution Approach 1:
The outer radius parameter of the rotor is changed along its longitudinal axis, transitioning from a constant value in conventional designs to a variable tapered value in this invention. This parameter variation compensates for thermal expansion effects while maintaining a relatively simple geometric form that can be manufactured using conventional techniques.
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 enhances the supercharger's efficiency by maintaining consistent clearances, reducing thermal expansion issues, and preventing scuff, thereby improving air flow and reducing parasitic losses.
Implementation Method 1
The efficiency of supercharger assemblies is compromised by thermal expansion, leading to increased likelihood of 'scuff' at the ends of counter-rotating rotors due to uneven clearances
Data Source
AI summary
A rotor assembly is provided for a compressor assembly having a housing defining an inlet port, outlet port, and a rotor cavity in communication with the inlet port and outlet port. The rotor assembly includes a rotor body having a plurality of lobes formed thereon and rotatably mountable within the rotor cavity of the housing. The rotor body has a first end, substantially adjacent to the inlet port, and a second end, substantially adjacent to the outlet port, when mounted within the housing. Each of the plurality of lobes has an outer radius that is greater at the first end than at the second end.