Multi-Stage Compressor Seals to Block Refrigerant Transfer
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Solution Overview
Problem
In multi-stage compressor systems, there is an unintended transfer of refrigerant between compressors due to channels configured to retain the drive shaft, leading to inefficiencies and complexity, particularly when multiple compressors are coupled in series.
Innovation Solution
The implementation of helical seals on the drive shaft, oriented in different directions, to inhibit refrigerant flow between compressor wheels and redirect it back towards the entrance, thereby enhancing sealing and reducing unintended refrigerant transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple compressors are coupled in series with channels to retain the drive shaft, then the compressor system can achieve higher pressure ratios and improved cooling performance, but unintended refrigerant transfer occurs between compressors through the drive shaft channel
Solution Approach 1:
A seal member is introduced as an intermediary element between the drive shaft and the channel wall. This seal member prevents direct communication between compressor stages through the channel, blocking the harmful refrigerant transfer path while allowing the drive shaft to rotate freely within the channel.
Solution Approach 2:
The channel is designed with different properties at different locations: it remains open and smooth in most sections to allow drive shaft rotation, but includes sealed sections where the seal member is positioned to prevent refrigerant leakage. This localized sealing approach maintains overall system functionality while addressing the specific problem of refrigerant transfer.
2Reliability
If traditional seals are used to prevent refrigerant leakage, then sealing performance is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The seal member is designed to be self-retaining within the channel, utilizing the channel's geometry and the seal's own elastic properties to maintain its position without additional retaining structures. The seal automatically adjusts to accommodate drive shaft rotation and positioning variations, providing reliable sealing through its inherent design rather than external constraints.
Solution Approach 2:
The seal member is designed with specific elastic properties and dimensional parameters that allow it to deform and conform to the channel geometry under operating conditions. By carefully selecting the seal's material properties and dimensions, reliable sealing is achieved without requiring complex mechanical retention systems.
3Reliability
If the drive shaft channel is completely sealed to prevent refrigerant transfer, then refrigerant leakage is prevented, but the drive shaft cannot rotate freely causing operational issues
Solution Approach 1:
The seal member acts as an intermediary that decouples the rotational freedom requirement from the sealing requirement. It allows the drive shaft to rotate freely within the channel while maintaining refrigerant containment, as the seal is positioned to seal against the channel wall rather than the rotating drive shaft surface.
Solution Approach 2:
The channel is segmented into different functional zones: unsealed sections that allow drive shaft rotation and access, and sealed sections where the seal member is positioned to prevent refrigerant transfer. This segmentation allows both rotational freedom and refrigerant containment to coexist in different parts of the same channel.
Data Source
AI summary
A compressor comprising: an drive shaft; a first compressor wheel; a second compressor wheel connected to the first compressor wheel via the drive shaft; and two or more helical seals disposed on the drive shaft, each helical seal of the two or more helical seals extending away from an outer surface of the drive shaft and around a circumference of the drive shaft, wherein the two or more helical seals are configured to inhibit flow of fluid between the first compressor wheel and the second compressor wheel.