Non-conductive Resin Can for Canned Motor Vacuum Pump
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Solution Overview
Problem
Conventional canned motors for vacuum pumps face issues with mechanical strength and efficiency due to eddy currents from magnetic flux and pressure fluctuations, leading to increased thickness requirements for the can member, which complicates manufacturing and maintenance.
Innovation Solution
A canned motor design with a can made of non-conductive resin, where the barrel portion is thin to reduce distance between the stator and rotor, and the closing portion is thicker to enhance mechanical strength, using reinforcing members and adhesives to integrate the stator core and can, and employing a specific shape and structure to minimize gas leakage and facilitate manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the can member is increased to prevent radially inward buckling distortion, then mechanical strength is improved, but the distance between the stator and rotor increases, deteriorating motor characteristics
Solution Approach 1:
The can member is designed with non-uniform thickness distribution: the closing portion (end caps) has greater thickness to resist buckling under pressure differential, while the barrel portion (side walls) has reduced thickness to minimize the air gap between stator and rotor. This local differentiation allows each region to have the thickness appropriate for its specific functional requirements.
Solution Approach 2:
The can member is constructed as a composite structure combining resin material with embedded reinforcing members (such as fibrous reinforcements). This composite construction provides high mechanical strength and buckling resistance in the closing portions while allowing the barrel portions to be made thinner, thus resolving the contradiction between strength and motor characteristics.
2Length of moving object
If the thickness of the can made of resin is reduced, then the distance between stator and rotor is reduced, but mechanical strength is lowered, making the can unable to resist pressure fluctuation
Solution Approach 1:
The resin can member is reinforced with strengthening members such as fibrous reinforcements (glass fibers, carbon fibers, or aramid fibers) embedded within the resin matrix. This composite structure maintains high mechanical strength and pressure resistance while allowing the overall can thickness to be reduced, thereby minimizing the air gap and improving motor characteristics.
Solution Approach 2:
Reinforcing members are strategically positioned within the can structure, with higher reinforcement density in the closing portions that experience the greatest pressure differential and buckling stress, while the barrel portions have sufficient but reduced reinforcement to maintain structural integrity at thinner dimensions.
3Strength
If the thickness of the can member is increased to maintain mechanical strength, then the can can resist pressure fluctuation, but manufacturing complexity and maintenance burden increase
Solution Approach 1:
The can member is manufactured as a composite molded product using injection molding or similar processes, where fibrous reinforcements are embedded within the resin matrix during a single manufacturing step. This integrated composite construction achieves high mechanical strength without requiring post-manufacturing assembly of separate reinforcement elements, thereby simplifying the manufacturing process and reducing complexity.
Solution Approach 2:
The can member serves multiple functions simultaneously: it provides mechanical strength to resist pressure differential, acts as a seal between the motor and pump chambers, and functions as a structural component of the motor housing. This multi-functionality reduces the need for additional separate components, simplifying both manufacturing and maintenance.
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
The design improves motor characteristics by reducing the thickness of the can while maintaining mechanical strength, simplifying manufacturing, and reducing maintenance burdens by minimizing gas leakage and enhancing sealing performance.
Implementation Method 1
an eddy current is generated in a surface under the effect of a magnetic flux from the motor stator
Implementation Method 2
employing a specific shape and structure to minimize gas leakage and facilitate manufacturing
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided is a canned motor to be coupled to a vacuum pump and used as a rotary driving source for the vacuum pump. The canned motor includes: a stator core; a rotor provided on an inner side of the stator core; and a non-conductive can provided between the stator core and the rotor. The non-conductive can is configured to separate the stator core and the rotor from each other. The non-conductive can is made of resin, ceramic, or composite material thereof. The non-conductive can is bonded to the stator core with an adhesive.