Multistage Centrifugal Pump Impeller Assembly With Adaptor Rings
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Solution Overview
Problem
Existing multistage centrifugal pumps face challenges in efficient assembly, vibration balancing, and high manufacturing costs, with complex assembly processes and temperature management issues complicating the assembly of impeller/shaft combinations.
Innovation Solution
The use of adaptor rings with a smaller shaft diameter and a hub design that allows for radial support through two adaptor rings, along with a cotter joint for torque transmission, simplifies assembly and balances radial and axial forces, enabling efficient and balanced impeller/shaft assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional impeller/shaft assembly design is used with interference fits and temperature management, then the connection strength between impeller and shaft is improved, but the assembly process becomes complex and time-consuming
Solution Approach 1:
An adaptor ring is introduced as an intermediary component between the impeller hub and the shaft. The adaptor ring has a first portion that fits into the hub and a second portion that fits onto the shaft, simplifying the connection process while maintaining strength. This mediator component eliminates the need for complex interference fits and temperature management during assembly.
Solution Approach 2:
The connection system is segmented into three separate components: the impeller hub, the adaptor ring, and the shaft. This segmentation allows each component to be manufactured independently with standard tolerances and assembled without complex temperature management, reducing assembly complexity while maintaining connection integrity.
2Manufacturing precision
If precise balancing of impeller/shaft assembly is achieved through complex assembly processes, then vibration balance is improved, but assembly time and manufacturing cost increase
Solution Approach 1:
The adaptor ring serves as a precision reference component that facilitates accurate positioning and balancing of the impeller on the shaft. By providing a standardized interface with controlled tolerances, it enables precise balancing to be achieved through simpler, faster assembly procedures rather than complex processes.
Solution Approach 2:
The adaptor ring is designed and manufactured with pre-established dimensional tolerances and geometric precision that facilitate accurate positioning. This preliminary preparation of the adaptor ring with precise dimensions allows for faster final assembly and balancing operations, reducing both time and cost.
3Ease of operation
If adaptor rings are used to transmit radial forces, then assembly simplicity is improved, but the ability to transmit axial forces is reduced
Solution Approach 1:
The adaptor ring is designed with differentiated functional zones: a first portion optimized for radial force transmission into the hub, and a second portion optimized for axial force transmission onto the shaft. This local specialization allows each portion to excel at its specific function, with the broad portion handling radial loads and the narrowed portion handling axial loads.
4Ease of operation
If the shaft diameter is made smaller than the hub inner diameter for adaptor ring fit, then assembly ease is improved, but the structural rigidity is reduced
Solution Approach 1:
The adaptor ring acts as a structural intermediary that compensates for the reduced shaft diameter. By providing a broader contact surface area through its first portion that fits into the hub, it distributes loads more effectively and maintains structural rigidity despite the shaft having a smaller diameter than the hub inner diameter.
Solution Approach 2:
The adaptor ring transitions the connection from a simple radial fit to a more complex three-dimensional arrangement with axial and radial components. The narrowed second portion extends axially to provide additional contact area and load distribution, compensating for the reduced radial dimension of the shaft.
Data Source
AI summary
A multistage centrifugal pump for pumping fluid includes a pump housing having a fluid inlet and a fluid outlet and a flow channel between the inlet and the outlet in the housing. The pump housing includes a number of pumping stages. A shaft is mounted by bearings for rotation about a center axis, and a number of impellers each including a hub having an axial opening are to be fitted on the shaft. When in operation, power is transmitted though the rotating shaft to the impellers, causing torque, radial forces and axial forces. Over the length of the shaft where the impellers are configured to be assembled, the shaft has a diameter that is smaller than the inner diameter of the hub and an adaptor ring is arranged in the axial opening of the hub to transmit the radial forces between the impeller and the shaft.