Sliding Face Dimple Geometry for Bidirectional Seal Lubrication
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Solution Overview
Problem
Existing sliding members, such as mechanical seals, face challenges in reducing friction and preventing fluid leakage regardless of rotation direction due to inefficiencies in generating hydrodynamic lubrication and sealing performance in current designs.
Innovation Solution
The design incorporates dimples on sliding faces with edges that extend radially, where fluid pressure becomes negative upon entry and positive upon blockage, creating a larger positive pressure region and reducing leakage by optimizing dimple arrangement for sliding speed and temperature, ensuring effective hydrodynamic lubrication and sealing regardless of rotation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic pressure generating grooves extend in the circumferential direction from only one side of the fluid introducing groove, then positive dynamic pressure can be generated in one rotation direction, but the structure cannot adapt to bidirectional rotation and fluid leaks to the low-pressure side
Solution Approach 1:
The dimple is designed with asymmetric radial edges where one edge extends farther in the circumferential direction than the other. This asymmetric configuration creates a directional flow path that generates positive dynamic pressure in one rotation direction while maintaining sealing effectiveness. The asymmetry allows the structure to optimize for a specific rotation direction rather than attempting symmetric bidirectional functionality.
Solution Approach 2:
Different regions of the dimple structure serve different functions: the upstream radial edge creates negative pressure to draw fluid in, while the downstream radial edge blocks fluid and generates positive pressure. This local differentiation of pressure zones within the single dimple structure enables both lubrication and sealing functions to coexist without requiring separate structures for each rotation direction.
2Adaptability or versatility
If dynamic pressure generating grooves are disposed on opposite sides of the fluid introducing groove, then bidirectional rotation is supported, but fluid flow efficiency decreases and hydrodynamic lubrication cannot be created
Solution Approach 1:
Rather than using symmetric grooves on both sides, the invention employs a single asymmetric dimple where the radial edges have different circumferential extents. This asymmetric design creates an optimized unidirectional flow path that maintains high fluid flow efficiency while the array of such dimples provides overall bidirectional rotation capability without the flow efficiency penalties of symmetric dual-sided grooves.
Solution Approach 2:
The lubrication function is divided into multiple discrete dimples arranged in an array rather than using continuous grooves. Each dimple acts as an independent fluid handling unit with its own upstream and downstream edges, allowing fluid to be processed in segmented portions throughout the sliding face, maintaining efficiency while enabling bidirectional operation.
3Reliability
If pressurized fluid is supplied to the low-pressure fluid side of the sliding face, then hydrodynamic lubrication is created, but sealing performance deteriorates due to fluid leakage
Solution Approach 1:
The dimple structure creates localized pressure zones where negative pressure exists at the upstream edge for fluid intake and positive pressure exists at the downstream edge for fluid blocking. This local pressure differentiation allows the system to maintain positive pressure on the low-pressure side in specific localized regions for lubrication while preventing overall fluid leakage, thus maintaining sealing performance while reducing friction.
Solution Approach 2:
The invention converts what would normally be harmful fluid leakage to the low-pressure side into a beneficial effect by using the downstream radial edge to block and pressurize the fluid. The potential leakage path is transformed into a pressure-generating mechanism where the blocked fluid creates positive dynamic pressure that improves lubrication while the blocked configuration simultaneously prevents harmful leakage.
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 generates sufficient positive pressure for hydrodynamic lubrication and improves sealing performance by reducing fluid flow to the low-pressure side, effectively reducing friction and leakage across all rotation directions.
Implementation Method 1
rotating the rotating sealing ring clockwise causes a fluid on the high-pressure side Y to flow through the fluid introducing grooves into the dynamic pressure generating grooves, thus generating dynamic pressure between the sealing face of the rotating sealing ring and the sealing face of a stationary sealing ring, thereby creating the state of hydrodynamic lubrication
Implementation Method 2
The pressure of a fluid that flows into the dimple from the edge on the upstream side becomes negative, and when the fluid is blocked by the edge on the downstream side, its pressure increases to become positive
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
To provide a sliding member that reduces friction regardless of the direction of rotation by interposing a fluid between sliding faces and that improves sealing performance regardless of the direction of rotation. A sliding member includes sliding faces S configured to slide in relation to one another, at least one sliding face 5 of the sliding faces being provided with a plurality of dimples 11 having multi-sided shapes whose edges are formed without interruption. A pair of the edges A1-B1, A1-C1 of each of the multi-sided dimples 11, extending radially on opposite sides of a radial axis R of the sliding member, are sloped to become farther apart as they extend toward a high-pressure fluid side, and an edge B1-C1, which connects end points B1, C1 on the high-pressure fluid side of the pair of the edges, is formed such that its length is not greater than the lengths of the pair of the edges A1-B1, A1-C1.