Shrouded Impeller Brazing With Interference-Fit Shroud Centering
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Solution Overview
Problem
Centrifugal compressors with imbalanced impellers, resulting from improper shroud alignment during metal joining processes, suffer from decreased efficiency and increased porosity, leading to inefficiencies and higher maintenance requirements.
Innovation Solution
The method involves attaching blades to a hub and a shroud with rings extending from the shroud's inner surface, forming an interference fit with the blades' tips to maintain a consistent gap during the brazing process, ensuring proper alignment and balance of the impeller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shroud is attached to the blades using a metal joining process such as brazing, then the impeller can be manufactured with a shroud, but the impeller becomes imbalanced if the shroud is not centered on the blades and hub during the joining process
Solution Approach 1:
The patent applies preliminary action by positioning the shroud on the blades and hub before the brazing process begins. The shroud is pre-centered using a locating mechanism that ensures proper alignment prior to joining, preventing imbalance issues that would occur if centering were attempted after attachment.
Solution Approach 2:
The patent introduces an intermediary locating mechanism between the shroud and the blades/hub assembly. This intermediary device serves as a mediator that maintains precise centering during the brazing process, allowing the shroud to be properly positioned without requiring complex alignment procedures during the actual joining operation.
2Device complexity
If the shroud is not centered on the blades and hub during the metal joining process, then the manufacturing process is simpler, but the impeller efficiency decreases due to imbalance and increased porosity
Solution Approach 1:
The locating mechanism is implemented before the brazing process to pre-establish proper shroud centering. This preliminary positioning action ensures that the shroud is correctly aligned with the blades and hub before any joining occurs, preventing imbalance and porosity issues without adding significant complexity to the overall manufacturing process.
Solution Approach 2:
The locating mechanism is designed to automatically center the shroud on the blades and hub through self-aligning features. This self-service approach eliminates the need for complex manual alignment procedures or additional adjustment steps, maintaining simplicity in the joining process while ensuring reliable impeller balance.
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 approach enhances the balance and efficiency of the impeller, reduces porosity in the brazed joint, and decreases maintenance needs by maintaining a consistent gap between the shroud and blades throughout the manufacturing process.
Implementation Method 1
applying a brazing compound to the tips of the blades and to the inner surface of the shroud... attaching the blades to the shroud using a brazing process
Implementation Method 2
The rings and the tips of the blades form an interference fit between the rings and the tips of the blades that maintains a consistent gap between the shroud and the blades during manufacture of the impeller
Data Source
AI summary
A method of manufacturing an impeller includes attaching blades to a hub. The impeller includes the blades, the hub, and a shroud. The blades each include a tip, and the shroud includes an inner surface and at least one ring extending from the inner surface. The method also includes applying a brazing compound to the tips of the blades and to the inner surface of the shroud. The method includes inserting the blades and the hub into the shroud such that the tips of the blades press against the rings. The rings and the tips of the blades form an interference fit between the rings and the tips of the blades that maintains a consistent gap between the shroud and the blades during manufacture of the impeller. A compressor including the impeller is also disclosed.