Mechanical Slip Ring Seal Layout for Oil-Lubricated Compressor Gears
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Solution Overview
Problem
Existing gear arrangements for oil-lubricated screw compressors face challenges in achieving simple and effective lubrication of the drive bearing on the transmission side and maintaining a compact design while ensuring reliable sealing of the drive shaft, often requiring complex and wear-prone lip seals.
Innovation Solution
A gear arrangement with a mechanical seal that includes a sliding ring and a non-rotatable mating ring, axially and radially fixed relative to the drive housing section, which seals the shaft passage opening and allows for oil-lubrication of the transmission-side drive bearing without additional measures, eliminating the need for separate grease lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lip seal is used to seal the drive shaft, then the sealing function is achieved, but the seal is wear-prone and has limited service life
Solution Approach 1:
The patent replaces the contact-based lip seal with a mechanical seal that uses a sliding ring and counter ring arrangement. The sliding ring rotates with the drive shaft while the counter ring remains stationary, creating a non-contact or minimal-contact sealing mechanism that reduces wear and extends service life while maintaining reliable sealing of the drive shaft against oil leakage.
Solution Approach 2:
The patent changes the sealing mechanism from elastic deformation (lip seal) to rigid sliding contact with controlled clearance (mechanical seal). By adjusting parameters such as the gap between the sliding ring and counter ring, and using appropriate sealing materials, the system achieves reliable sealing with significantly reduced wear compared to lip seals.
2Manufacturing precision
If the drive shaft is fully supported in the motor housing before installing the seal, then the seal can be centered, but the seal shields the gearbox-side drive bearing from lubricating oil
Solution Approach 1:
The patent divides the sealing function into two parts: the sliding ring that rotates with the drive shaft and the counter ring that remains stationary in the housing. This segmentation allows the drive shaft to be supported and positioned independently while the seal components are installed separately, enabling proper lubrication of the gearbox-side drive bearing without compromising seal centering.
Solution Approach 2:
The patent introduces a receiving space in the drive housing section that accommodates both the mechanical seal and the gearbox-side drive bearing. This receiving space acts as an intermediary zone that allows lubricating oil to reach the drive bearing while the mechanical seal performs its sealing function, thus resolving the conflict between seal centering and bearing lubrication.
3Reliability
If a mechanical seal with sliding ring and counter ring is used, then sealing reliability is improved and wear is reduced, but the device complexity increases
Solution Approach 1:
The patent designs the mechanical seal such that the sliding ring and counter ring serve multiple functions: sealing the drive shaft, supporting the drive shaft, and guiding the sliding ring. The counter ring is axially and radially fixed relative to the drive housing section, providing both sealing and positioning functions, which simplifies the overall design while maintaining high reliability.
Solution Approach 2:
The patent combines the sealing function with the support and guidance functions into a single mechanical seal assembly. The sliding ring and counter ring work together as an integrated unit that simultaneously seals the drive shaft, supports it radially, and guides its rotation, thereby reducing the need for separate components and minimizing overall device complexity.
4Ease of manufacture
If the gearbox-side drive bearing is positioned between the shaft seal and drive gear, then oil-lubrication is enabled, but the assembly process becomes more complex
Solution Approach 1:
The patent positions the gearbox-side drive bearing in the receiving space between the mechanical seal and the drive gear during the assembly process. This preliminary positioning allows the bearing to be lubricated by oil from the gear chamber while maintaining a structured assembly sequence that does not significantly increase overall assembly complexity.
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 mechanical seal provides long-lasting, reliable sealing with reduced wear, simplifies assembly, and allows for the use of existing components, ensuring the drive shaft remains pressure-free and preventing oil leakage into the engine compartment.
Implementation Method 1
The sealing effect is achieved through contact (dynamic sealing) between the axial sliding surfaces of a seal ring and a mating ring
Implementation Method 2
allows for oil-lubrication of the transmission-side drive bearing without additional measures
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The invention relates to a gear assembly (1) for connecting a drive motor (2) and an oil-lubricated compressor block (3), in particular a screw compressor, and to a method for assembling a gear assembly. The gear assembly (1) comprises a housing (4) forming a gear chamber (11), wherein the housing (4) has a shaft passage opening (43) between a motor chamber (12) and the gear chamber (11), a drive shaft (7), an oil-lubricated gear stage (9) arranged in the gear chamber (11) and coupling the drive shaft (7) to an output shaft (8) of the compressor block (3), and a shaft seal (5) for sealing the shaft passage opening (43) against oil leakage from the gear chamber (11) into the motor chamber (12), wherein the shaft seal (5) and a gear-side drive bearing (20) are received in a receiving chamber (13).wherein the gearbox-side drive bearing (20) is arranged between the shaft seal (5) and a drive gear of the gearbox stage (9), wherein the shaft seal (5) is designed as a mechanical seal with a sliding ring (51) arranged in a rotationally secure manner relative to the drive shaft (7) and a counter ring (52) fixed axially and radially relative to the drive housing section.