Electric Secondary Air Pump With Volute-Embedded Vaned Diffuser
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Solution Overview
Problem
Centrifugal compressors in secondary air pumps face challenges in maintaining stability at very low flow rates, as conventional surge prevention techniques become ineffective, leading to flow instabilities.
Innovation Solution
Incorporation of a vaned diffuser ring embedded within the volute of the centrifugal compressor, altering air flow dynamics to stabilize operation at low flow rates, combined with an optional recirculation channel for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional centrifugal compressor design is used, then the compressor can operate at higher flow rates, but flow instabilities occur at very low flow rates near the surge line
Solution Approach 1:
The vaned diffuser ring is embedded within the volute housing, nesting the diffuser structure inside the existing compressor architecture. This integrated design allows the diffuser vanes to be positioned within the volute space, creating a compact configuration that improves low-flow stability without requiring additional external components.
Solution Approach 2:
The invention introduces a vaned diffuser ring with specific vane geometry and angular orientation to alter the flow parameters. The diffuser vanes create controlled expansion and redirection of the air flow, changing the flow characteristics to delay surge and improve stability at very low flow rates where conventional designs fail.
2Stress or pressure
If higher pressure ratios are demanded from the compressor, then emission control performance improves, but the compressor operates closer to the surge line causing flow instabilities
Solution Approach 1:
The vaned diffuser ring modifies the pressure distribution and flow velocity profile through its vane structure. By controlling the expansion angle and vane orientation, the diffuser enables higher pressure ratios to be achieved while maintaining flow attachment and preventing surge, thus improving low-flow stability at elevated pressure conditions.
Solution Approach 2:
The diffuser ring acts as an intermediary component between the compressor wheel and the volute outlet. It mediates the transition from high-velocity compressed air to lower-velocity flow in the volute, reducing flow instabilities and delaying surge while enabling higher pressure ratios to be sustained.
3Stability of the object's composition
If the vaned diffuser ring is embedded within the volute, then low flow rate stability improves, but the device complexity increases
Solution Approach 1:
The vaned diffuser ring is nested within the existing volute housing space, utilizing the available volume without requiring additional external components. This integration approach improves low-flow stability while minimizing the increase in overall device complexity by embedding the diffuser structure within the existing architecture.
Solution Approach 2:
The vaned diffuser ring serves multiple functions: it acts as a flow straightener, a pressure recovery device, and a surge prevention mechanism. By combining these functions into a single embedded component, the invention improves low-flow stability without proportionally increasing device complexity, as the diffuser performs multiple roles simultaneously.
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
The vaned diffuser ring shifts the peak efficiency line to lower flow rates, improving aerodynamic performance and pressure ratio, while reducing aerodynamic losses and enhancing stability, particularly at low flow conditions.
Implementation Method 1
a vaned diffuser ring fixedly mounted within the housing assembly radially outward of the compressor wheel and comprising an annular vane plate having a first side and an opposite second side and a plurality of circumferentially spaced vanes
Implementation Method 2
a centrifugal compressor comprising a housing assembly and a compressor wheel mounted in the housing assembly and connected to a rotatable shaft for rotation therewith about a rotational axis
Data Source
AI summary
An air pump includes a compressor having a compressor wheel mounted in a housing assembly defining an air inlet for leading air flow into the compressor wheel and defining a volute for receiving compressed air from the compressor wheel. A vaned diffuser ring is mounted within the housing assembly radially outward of the compressor wheel and includes an annular vane plate and a plurality of circumferentially spaced vanes having proximal ends rigidly attached to a first side of the plate, the vanes extending axially from the vane plate and distal ends of the vanes being disposed proximate a first wall of the housing assembly axially spaced from the plate such that a vaned diffuser passage is defined between said first wall and the vane plate. The vaned diffuser ring is embedded within the volute such that a second side of the vane plate is wetted by air within the volute.