Flywheel Assembly with Segmented Bearing Chamber
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Solution Overview
Problem
Flywheel assemblies face challenges in maintaining a low-pressure environment within the housing due to gas emission from fibre composite materials, which accelerates the degradation of bearing grease and increases gas pressure, affecting the flywheel's operation.
Innovation Solution
The flywheel assembly incorporates a secondary chamber for the bearings with a molecular pump to manage gas pressure, allowing the use of greases with higher vapour pressures and includes an additional pump to control pressure in the secondary chamber, preventing gas buildup in the primary chamber containing the flywheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearings are placed in the low-pressure primary chamber with the flywheel, then the bearing grease will maintain its lubricating properties longer, but the grease will release gas and off-gas causing accelerated degradation
Solution Approach 1:
The patent divides the housing into two separate chambers: a primary chamber containing the flywheel and a secondary chamber containing the bearings. This segmentation isolates the bearing grease from the low-pressure environment, preventing off-gassing into the primary chamber while allowing the use of conventional greases with higher vapor pressures in the secondary chamber.
2Quantity of substance
If fibre composite materials are used in high energy density flywheels, then energy density is improved, but gases are emitted long after fabrication making it difficult to maintain near vacuum conditions
Solution Approach 1:
By separating the flywheel (primary chamber) from the bearings (secondary chamber), the patent contains the gas emissions from fibre composite materials within the primary chamber. The molecular pump then manages the pressure in the primary chamber independently, allowing high energy density flywheels to be used without compromising the overall vacuum environment.
Solution Approach 2:
The molecular pump acts as an intermediary device that actively removes gas molecules from the primary chamber, counteracting the continuous gas emission from fibre composite materials. This allows the system to maintain near vacuum conditions in the primary chamber despite the presence of gas-emitting composite materials.
3Productivity
If a molecular pump is used to pump gas molecules from the primary chamber to the secondary chamber, then low pressure environment is maintained in the primary chamber, but the gas pressure in the secondary chamber increases
Solution Approach 1:
The molecular pump serves as an intermediary that transfers gas molecules from the primary chamber to the secondary chamber, maintaining low pressure in the primary chamber while isolating the pressure increase in the secondary chamber. This allows the flywheel to operate efficiently in a vacuum environment without being affected by the pressure buildup in the bearing chamber.
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 maintains a stable low-pressure environment in the flywheel chamber while enabling the use of more common greases, reducing degradation and ensuring efficient operation by isolating bearing off-gassing effects from the flywheel's pressure conditions.
Implementation Method 1
it may be a molecular drag pump which includes a spiral groove formed on the hub
Implementation Method 2
The additional pump may be a getter pump or a vacuum pump, for example
Implementation Method 3
Providing the bearings in a second, higher pressure chamber is beneficial where the bearings require a grease which has a high vapour pressure
Data Source
Figure 1
AI summary
A flywheel assembly (2) is described which is suitable for use as a compact power storage device. The assembly comprises a housing (8), a flywheel (4) coupled to a shaft (6) which is rotatably mounted in the housing via bearings (18, 20), a primary chamber (14) which is defined within the housing and contains the flywheel, and a secondary chamber (26) which is defined within the housing and contains the bearings. Furthermore, it includes a molecular pump (28, 30) driven by the shaft for pumping gas molecules from the primary chamber to the secondary chamber. Location of the bearings in a high pressure chamber inhibits off-gassing from the bearing grease. Furthermore, any such off-gassing under load will not increase the gas pressure in the first chamber containing the flywheel as it is separate from the secondary chamber containing the bearings.