Mainline Electric Oil Pump Assembly with Zero-Backlash Collet Clamping
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Solution Overview
Problem
Mainline electric oil pump assemblies face issues with noise, vibrations, and reduced reliability due to existing designs that do not adequately address stress concentrations, bearing gaps, and thermal aging, particularly in the nuclear industry context.
Innovation Solution
The solution involves a mainline horizontal single-stage double-volute pump assembly with a double-sided collet clamping device, tailored roller bearings, and self-correcting mounting supports, along with a compensating dual disc coupling, to reduce stress concentrations and vibrations, and improve assembly precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible coupling with rubber elements is used to connect pump and motor shafts, then the coupling can accommodate misalignment, but the rubber elements undergo thermal aging and elasticity coefficient changes under large temperature variations and oil vapour exposure
Solution Approach 1:
The patent replaces the rubber flexible coupling with a metallic flexible coupling consisting of a cross-shaped element with flexible arms. This substitution eliminates the thermal aging and elasticity degradation problems of rubber while maintaining the ability to accommodate shaft misalignment through the flexible metallic arms that can bend and deform elastically under thermal and mechanical loads.
2Stability of the object's composition
If keys and key grooves are used to connect impeller halves to the rotor shaft, then the impeller can be balanced, but the shaft is weakened and stress concentrations occur
Solution Approach 1:
The patent removes the keys and key grooves from the shaft design entirely. Instead, the impeller halves are connected to the rotor shaft through a non-splined, zero-backlash collet clamping device that provides the necessary mechanical connection without cutting into the shaft material, thereby preserving shaft strength and eliminating stress concentrations while still allowing for impeller balancing.
Solution Approach 2:
Rather than using traditional keyed connections where the shaft has grooves cut into it, the invention inverts the approach by using a clamping device that surrounds and secures the impeller to the shaft surface, eliminating the need to compromise the shaft's structural integrity for balancing purposes.
3Ease of manufacture
If bearing gaps are present in sliding supports, then assembly is simplified, but dynamic beats occur and vibration and noise increase
Solution Approach 1:
The patent applies preliminary action by pre-assembling bearing pairs in a controlled environment where gaps between bearing components can be precisely adjusted and eliminated before final installation. This allows the bearing gaps to be closed off proactively during assembly, preventing dynamic beats and vibration issues while maintaining manufacturing simplicity through the use of pre-prepared bearing pairs with adjusted clearances.
Data Source
AI summary
The mainline electric oil pump assembly relates to the field of assemblies for pumping oil in main oil pipelines. The aim of the present invention is to create a mainline electric oil pump assembly with improved technical and economic characteristics, reduced noise and vibrations, and increased reliability, service life and performance. The main distinguishing features of the proposed assembly which contribute to the achievement of the aforementioned aim are: the non-splined, zero-backlash seating of the impeller on a smooth shaft, the use of roller bearings seated in a non-splined, zero-backlash fashion on the smooth shaft, the use of mechanical seals seated in a non-splined, zero-backlash fashion on the smooth shaft, the use of self-correcting adjustable spherical supports under the supporting feet of the pump, and the boring of the seating surfaces of the pump housing for the rotor in a single set-up operation.