Power transmission device
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Solution Overview
Problem
Existing power transmission devices face challenges in increasing torque and pressure resistance without complicating the structure or increasing costs, particularly when applied to expansion valves in vehicle air conditioners, where downsizing and high-pressure refrigerant handling are critical.
Innovation Solution
The power transmission device incorporates a drive-side magnet, a stationary magnet, a pole piece, and a sealing member, where the stationary magnet has more poles than the drive-side magnet, and the pole piece modulates magnetic flux to increase the reduction gear ratio and pressure resistance, with the sealing member independently enhancing pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the number of magnet poles is increased to increase torque, then the torque increases, but the device complexity and manufacturing cost increase
Solution Approach 1:
A pole piece is introduced as an intermediary component between the drive-side magnet and the stationary magnet. The pole piece includes multiple magnetic body portions that interact with the magnets to generate torque, allowing torque enhancement without increasing the number of magnet poles. This mediator structure enables complex magnetic field interactions while keeping the magnet configuration simple.
Solution Approach 2:
The pole piece is segmented into multiple magnetic body portions (first, second, third magnetic body portions) with different pole numbers. Each segment interacts with the magnets to contribute to torque generation. This segmentation allows optimization of torque characteristics without complicating the overall magnet structure.
2Stress or pressure
If the number of magnet poles is increased to increase pressure resistance, then the pressure resistance increases, but the device complexity and manufacturing cost increase
Solution Approach 1:
The pole piece acts as a structural intermediary that enhances pressure resistance. The multiple magnetic body portions are arranged to distribute and withstand pressure forces from the refrigerant. This intermediary structure provides mechanical strength without requiring additional magnets or complex magnet arrangements.
Solution Approach 2:
The power transmission device uses composite construction with the pole piece combining multiple magnetic body portions with different properties. This composite structure optimizes both magnetic performance and mechanical strength, providing enhanced pressure resistance without increasing device complexity.
3Ease of manufacture
If the magnetic gear structure is simplified to reduce costs, then the manufacturing cost decreases, but the reduction gear ratio and torque capability are reduced
Solution Approach 1:
The invention changes the parameter of pole piece configuration rather than magnet pole number. By adjusting the number and arrangement of magnetic body portions in the pole piece, the reduction gear ratio can be optimized while keeping the magnet structure simple and cost-effective. This parameter change approach maintains manufacturing simplicity while achieving high reduction ratios.
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 configuration effectively increases the reduction gear ratio and pressure resistance without changing the number of magnet poles, simplifying the structure and reducing costs, while ensuring reliable operation under high-pressure conditions.
Implementation Method 1
the pole piece includes a plurality of magnetic body portions and rotates by modulating a magnetic flux between the drive-side magnet and the stationary magnet
Data Source
AI summary
A power transmission device includes: a pole piece configured to rotate by modulating a magnetic flux between a drive-side magnet and a stationary magnet; and a sealing member that partitions an inside of a housing into a driving side space where the drive-side magnet is disposed and a driven side space where the stationary magnet and the pole piece are disposed, so as to seal fluid between the driving side space and the driven side space. The pole piece and the stationary magnet have a cylindrical shape and are disposed coaxially with and radially outer side of the drive-side magnet. The sealing member includes: a sealing cylinder portion positioned radially outer side of the drive-side magnet; and a sealing bottom surface portion covering the sealing cylinder portion from the driving side space.