Impeller Rotor Assembly Using Sleeve and Nut Constraint
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Solution Overview
Problem
The existing impeller and shaft assembly in rotary machines, such as centrifugal compressors, is time-consuming due to interference fit constraints, which hinder efficient assembly.
Innovation Solution
A rotor assembly method involving a shaft with an insertion hole, a connecting shaft with a screw part, a sleeve fixed to the shaft, and a nut that pinches and fixes the impeller with the sleeve, constraining the impeller and shaft positions in the circumferential and radial directions through contact faces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference fit is used to constrain the impeller and shaft in radial and circumferential directions, then the constraint reliability is improved, but the assembly time increases
Solution Approach 1:
The constraint function is divided into two independent parts: (1) the sleeve provides radial and circumferential constraint through its fitted structure on the shaft, and (2) the nut provides axial constraint by pressing the impeller against the sleeve. This segmentation allows each component to specialize in specific constraint directions, enabling faster assembly while maintaining reliability.
Solution Approach 2:
The sleeve is pre-installed on the shaft before the impeller assembly process. This preliminary action prepares the radial and circumferential constraint structure in advance, so that when the impeller is installed, only the axial constraint needs to be completed by tightening the nut, significantly reducing assembly time.
2Reliability
If interference fit structure is adopted, then the firm constraint in radial and circumferential directions is achieved, but the ease of assembly deteriorates
Solution Approach 1:
The constraint system is segmented into radial-circumferential constraint (sleeve) and axial constraint (nut). The sleeve's fitted structure on the shaft provides stable radial and circumferential positioning, while the nut provides simple axial positioning. This segmentation makes the assembly process more intuitive and easier to operate.
Solution Approach 2:
The sleeve acts as an intermediary component between the shaft and impeller. It provides a prepared interface that guides the impeller into correct radial and circumferential positions, making the overall assembly process easier and more accurate.
3Stability of the object's composition
If interference fit is used to fix the impeller to the shaft, then the structural stability is improved, but the assembly complexity increases
Solution Approach 1:
The assembly is segmented into two independent constraint systems: the sleeve-shaft fitted structure for radial-circumferential stability, and the nut-impeller-sleeve pressing structure for axial stability. This segmentation simplifies the assembly process by making the constraint functions independent and modular.
Solution Approach 2:
The sleeve serves multiple functions: it is fitted on the shaft to provide radial and circumferential constraint, and simultaneously serves as a pressing surface for the nut to provide axial constraint. This multi-functionality reduces the number of components and simplifies the overall assembly structure.
Data Source
AI summary
A rotor includes: a shaft extending in an axial direction in which an axis extends centered on the axis; a connecting shaft connected to an end portion of the shaft on a first side in the axial direction and having a screw part formed at a tip portion of the connecting shaft; and an impeller including an impeller body formed in a disc-like shape centered on the axis and an insertion hole which is formed in a center portion of the impeller body passing through in the axial direction and through which the connecting shaft is inserted.