Turbomachine Shaft Sealing Arrangement with Oil Diffuser
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Solution Overview
Problem
Conventional turbocharger and turbomachine shaft sealing arrangements face challenges in preventing oil leakage due to pressure differentials between bearing and housing compartments, particularly at low boost pressures or during engine braking, which can lead to oil leakage into compressor or turbine housings and subsequent contamination.
Innovation Solution
An oil diffuser device is integrated between the bearing assembly and the housing, featuring a passage with increasing diameter and surface area, decelerating oil flow to prevent separation and allowing it to pour out under gravitational influence, combined with a labyrinth member for oil collection and directed drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing arrangements are used, then the structure is simple, but oil leakage occurs due to pressure differentials between bearing housing and compressor/turbine housings
Solution Approach 1:
A non-contact seal arrangement is introduced as an intermediary component between the bearing housing and the compressor/turbine housings. This seal arrangement includes a seal ring with sealing surfaces that interface with the shaft, creating a barrier that prevents oil leakage while managing pressure differentials without requiring complex mechanical contact seals
Solution Approach 2:
The harmful oil leakage path is extracted and redirected through a dedicated oil drainage passage. The passage is configured to collect and drain oil away from the sealing interface, removing the problematic fluid from the sealing zone and preventing contamination of the compressor or turbine housing
2Reliability
If positive contact seals are used, then sealing effectiveness improves, but friction losses and wear increase at high rotational speeds
Solution Approach 1:
The positive contact seal mechanism is replaced with a non-contact seal arrangement. Instead of relying on mechanical contact between sealing surfaces, the invention uses a seal ring positioned close to the shaft surface without contact, eliminating friction-based energy losses while maintaining sealing effectiveness through carefully controlled clearance and pressure management
3Reliability
If oil slinger is used to prevent oil leakage, then oil control improves, but the arrangement becomes more complex and oil may still leak into compressor housing at low boost pressures
Solution Approach 1:
The oil control function is merged with the seal ring structure itself. The seal ring incorporates both sealing surfaces for gas tightness and integrated oil drainage passages that directly channel oil away from the sealing interface. This consolidation eliminates the need for separate oil slingers or complex oil management systems, achieving effective oil control with a unified, simpler component
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 solution effectively restricts oil leakage and gas flow, maintaining sealing performance even at high boost pressures and high rotational speeds, directing oil to a controlled drain and preventing contamination in the turbine housing.
Implementation Method 1
decelerating oil flow to prevent separation and allowing it to pour out under gravitational influence
Implementation Method 2
An oil diffuser device is integrated between the bearing assembly and the housing, featuring a passage with increasing diameter and surface area, decelerating oil flow to prevent separation and allowing it to pour out under gravitational influence
Implementation Method 3
combined with a labyrinth member for oil collection and directed drainage
Data Source
Figure 1
Figure 2~2a
Figure 3a~3d
AI summary
A rotating machine (1) comprising such as an axial power turbine or a turbocharger has a housing (5) with a bearing cavity (8) and a chamber separated by a first wall. A shaft (7) is rotatable about an axis in the bearing cavity, extends through an opening in the first wall (13) and is mounted for rotation on a bearing assembly (10) provided in the bearing cavity. An oil sealing arrangement (30) including an oil diffuser device (31) is arranged on the shaft for displacing oil away from the shaft as it rotates. This restricts the flow of oil to the opening. The oil diffuser device defines a diffuser passage (39) between the bearing assembly and the first wall, the passage extending outwardly of the axis.