Permanent Magnet Pump Motor Rotor Assembly via Bearing Bracket Cavities
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Solution Overview
Problem
The assembly and maintenance of permanent magnet rotating electric machines in LNG pump motors are hindered by the constant magnetic attractive force, which complicates the insertion and removal of the rotor into the stator, as existing methods are not suitable for large-sized motors operating at high speeds.
Innovation Solution
The design includes bearing brackets with cavities for the rotor shaft and joint shaft, allowing for axial movement and insertion/removal while preventing radial movement due to magnetic forces, along with the use of nonmagnetic materials and specialized jigs to manage the magnetic attractive force during assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent magnet rotor is used in an LNG pump motor, then motor efficiency and performance are improved, but the constant magnetic attractive force hampers insertion and removal of the rotor during assembly and maintenance
Solution Approach 1:
The patent applies preliminary action by equipping the rotor with protrusions that engage with recesses in the stator before the rotor is fully inserted. This preliminary engagement mechanism allows the rotor to be positioned and secured during assembly without requiring complex external fixtures or tools to counteract the magnetic attractive force, thereby improving assembly ease while maintaining motor efficiency
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of protrusions and recesses that mediate between the rotor and stator during assembly. These mechanical features serve as intermediaries that facilitate rotor insertion and removal by providing predetermined engagement points that guide the assembly process and reduce the impact of magnetic attractive forces
2Manufacturing precision
If the rotor is fixed radially during assembly to prevent movement, then insertion accuracy is improved, but the pump structure requires additional insertion jig or tooling
Solution Approach 1:
The patent merges the rotor protrusions with the stator recesses to create an integrated engagement system. This merging of features eliminates the need for separate insertion jigs or tooling by incorporating the positioning and fixing functions directly into the rotor and stator structures, thereby maintaining insertion accuracy while reducing overall device complexity
Solution Approach 2:
The rotor and stator are designed to be self-servicing during assembly through the protrusion-recess mechanism. The rotor's own protrusions engage with the stator's recesses to automatically position and secure the rotor without requiring external fixing devices or complex tooling, thus achieving high insertion accuracy with minimal additional structural complexity
3Ease of operation
If existing assembly methods are used for induction motors, then assembly simplicity is maintained, but they are not suitable for large-sized permanent magnet motors operating at high speeds
Solution Approach 1:
The patent applies segmentation by dividing the rotor structure into distinct features (protrusions) that can independently engage with corresponding stator features (recesses). This segmentation allows the assembly method to be adapted to large-sized high-speed permanent magnet motors while maintaining relative simplicity, as the segmented engagement points provide controlled positioning without requiring complete redesign of the assembly process
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 assemblability and maintainability of permanent magnet pump motors by effectively managing the magnetic attractive force, enabling efficient and safe insertion and removal of the rotor, suitable for high-speed, large-sized motors.
Implementation Method 1
the rotor in a permanent magnet rotating electric machine is magnetized at all times and, particularly when the rotor is to be inserted in the stator, a measure needs to be taken for considering a magnetic attractive force
Data Source
AI summary
In a permanent magnet pump motor comprising a stator and a rotor, a permanent magnet is used for the rotor; and the rotor has a shaft end portion to be mounted with a joint shaft for rotor insertion and bearing brackets for housing therein bearings for supporting the both ends of the rotor. The bearing brackets have cavities through which a rotor shaft and the joint shaft can pass.