Seal Ring Pocket Geometry for Low Friction and Oil Leakage Control
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Solution Overview
Problem
Existing seal rings for hydraulic machines face a trade-off between reducing friction loss and preventing oil leakage, as thick oil films can lead to leakage issues.
Innovation Solution
A seal ring design featuring symmetrical pockets with specific inclined surfaces and R-surface configurations that facilitate oil inflow and pressure buildup, reducing friction loss while minimizing oil leakage by ensuring oil flows deeply into the pockets without escaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the oil film is made thick to reduce friction loss, then the lubrication property is enhanced, but the oil leakage increases
Solution Approach 1:
The pocket is divided into multiple regions with different inclination angles (first inclined portion with larger angle, second inclined portion with smaller angle). This segmentation allows the pocket to perform multiple functions: the first inclined portion facilitates oil inflow to build pressure, while the second inclined portion prevents oil leakage by creating a gradual transition to the circumferential end portion.
Solution Approach 2:
Different regions of the pocket are given different local properties through varying inclination angles. The first inclined portion has a larger angle to promote oil entry and pressure buildup, while the second inclined portion has a smaller angle to prevent oil escape. This local differentiation resolves the contradiction between needing thick oil films for lubrication and preventing oil leakage.
2Loss of energy
If the pocket is opened widely on the inner circumferential surface to facilitate oil inflow, then the friction loss is reduced, but the oil leakage increases
Solution Approach 1:
The pocket structure creates a dynamic oil flow path where oil enters through the widely opened first inclined portion, builds pressure, then flows through the controlled second inclined portion to the circumferential end portion. This dynamic design allows the pocket to facilitate oil inflow for friction reduction while the gradual narrowing prevents leakage.
3Loss of energy
If the inclined portion has a large angle to allow easy oil entry, then the friction loss is reduced, but the oil channel opening reduces too quickly causing oil escape
Solution Approach 1:
The inclined portion is segmented into two distinct sections: the first inclined portion with a larger angle for easy oil entry and pressure buildup, and the second inclined portion with a smaller angle for controlled oil flow. This segmentation prevents the oil channel opening from reducing too quickly, maintaining sealing property while reducing friction loss.
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 seal ring effectively reduces friction loss and oil leakage, maintaining sealing properties and operational efficiency regardless of rotation direction, with improved work efficiency and reduced oil pressure leakage.
Implementation Method 1
When oil pressure is applied on that seal ring, oil enters the pocket. The oil entering the pocket adds canceling pressure to lower pressure applied on the groove of the shaft from the seal ring.
Implementation Method 2
the oil entering the pocket flows into a gap between the seal ring and the shaft and forms an oil film between the seal ring and the shaft. Such oil film formation enhances a lubrication property of the seal ring, and the friction loss is reduced
Implementation Method 3
The inclined portions each include at least one ridge portion, a first inclined portion extending between the bottom portion and the ridge portion and forming a first angle with respect to the side surface, and a second inclined portion extending between the circumferential end portion and the ridge portion and forming a second angle smaller than the first angle with respect to the side surface.
Data Source
AI summary
[Object] To provide a seal ring capable of both reducing a friction loss and reducing oil leakage.[Solving Means] A seal ring includes: an inner circumferential surface; an outer circumferential surface orthogonal to the inner circumferential surface; side surfaces orthogonal to the inner circumferential surface and the outer circumferential surface; and a plurality of pockets provided, spaced apart from one another in one of the side surfaces. The plurality of pockets each have a symmetrical shape in a circumferential direction and are opened on a side of the inner circumferential surface and closed on a side of the outer circumferential surface. The plurality of pockets each include circumferential end portions that are provided in end portions in the circumferential direction and are R-surfaces each having a convex shape connected to the side surface, a bottom portion provided in a central region in the circumferential direction, and inclined portions each extending between each of the circumferential end portions and the bottom portion. The inclined portions each include at least one ridge portion, a first inclined portion extending between the bottom portion and the ridge portion and forming a first angle with respect to the side surface, and a second inclined portion extending between the circumferential end portion and the ridge portion and forming a second angle smaller than the first angle with respect to the side surface.