Planetary Gear Lubrication Structure With Pressure-Relief Bypass Seals
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Solution Overview
Problem
High lubricating oil pressure and fast peripheral speed in planetary gear devices make it difficult to use seal rings effectively, resulting in significant oil leakage even with pressure reduction mechanisms.
Innovation Solution
Incorporating bypass passages and pressure reduction mechanisms, such as labyrinth seals or secondary seal rings, to reduce the pressure difference across seal rings, allowing their use in high-pressure and high-speed conditions while minimizing oil leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seal rings are used in high-pressure and high-speed conditions, then sealing performance deteriorates, but using alternative seals like gap seals or labyrinth seals increases oil leakage
Solution Approach 1:
The sealing system is divided into multiple components: seal rings positioned at specific locations, bypass passages for pressure equalization, and pressure reduction mechanisms. This segmentation allows each component to perform its specific function - seal rings provide sealing where needed, while bypass passages handle pressure management separately.
Solution Approach 2:
Bypass passages act as intermediary channels that provide an alternative path for lubricating oil flow. These passages bypass the seal rings and include pressure reduction mechanisms that equalize pressure differences, preventing excessive pressure from damaging the seal rings while maintaining their sealing function.
2Reliability
If pressure reduction mechanisms are added to reduce oil leakage, then device complexity increases, but without them seal rings cannot function in high-pressure conditions
Solution Approach 1:
The pressure reduction mechanisms are merged with the existing sealing structure. The bypass passages are integrated into the tubular body and annular body, and the pressure reduction features are combined with the seal ring assembly, creating a compact integrated system rather than separate added components.
Solution Approach 2:
The pressure reduction mechanisms automatically equalize pressure differences through the bypass passages without requiring external control systems. The system self-regulates by allowing oil to flow through the bypass passages when pressure differences exceed certain thresholds, reducing the PV value at the seal rings automatically.
3Reliability
If bypass passages are created to reduce pressure difference across seal rings, then oil leakage through bypass passages increases, but without bypass passages seal rings fail in high-pressure conditions
Solution Approach 1:
The bypass passages are designed with specific geometric parameters (cross-sectional area, length, orientation) that control the flow characteristics. By carefully selecting these parameters, the passages provide sufficient pressure equalization while limiting excessive oil flow. The pressure reduction mechanisms further adjust flow parameters to maintain optimal balance.
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
Enables the use of seal rings in high-pressure and high-speed environments by reducing the pressure difference across them, thereby minimizing oil leakage and maintaining effective lubrication in planetary gear devices.
Implementation Method 1
The outer peripheral surface of the tubular body slides against the inner peripheral surface of an annular body
Implementation Method 2
a pair of pressure reduction mechanisms each limits a flow of lubricating oil between the tubular body and the annular body
Data Source
Figure 1
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AI summary
An oil supply structure for a planetary gear device includes: a planetary gear device (2) including a tubular body (4) that rotates together with a carrier (3) that holds planetary gears (22), the tubular body (4) including a lubricating oil introduction port (44) formed therein; an annular body (5) that slides against the tubular body (4), the annular body (5) including a lubricating oil supply passage (51) that communicates with the lubricating oil introduction port (44); a pair of seal rings (7) attached to the tubular body (4) or the annular body (5) at both sides of the lubricating oil introduction port (44) in an axial direction; bypass passages (71) bypassing the pair of respective seal rings (7); and a pair of pressure reduction mechanisms (6) disposed between the lubricating oil introduction port (44) and the pair of seal rings (7) or disposed outside the pair of seal rings (7), the pair of pressure reduction mechanisms each limiting a flow of lubricating oil between the tubular body (4) and the annular body (5).