Sliding Component Dimple Geometry for Leakage Control
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Solution Overview
Problem
Existing sliding components face challenges in balancing sealing and lubrication performance across varying pressure differences, leading to leakage issues due to irregular fluid movement and pressure gradients.
Innovation Solution
The design features dimples on the sealing faces with a cavitation formation region on the upstream side closer to the low-pressure side and a positive pressure generation region on the downstream side, with a tapered edge on the low-pressure side to smooth fluid movement and a Rayleigh step on the high-pressure side for efficient pressure release, reducing leakage and enhancing sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plurality of dimples are provided on a sealing face to enable fluid suction and return, then both leak prevention and lubrication functions are achieved regardless of pressure difference magnitude, but the basic crank shape of each dimple creates excessive dynamic pressure generation on the low-pressure side and prevents sufficient distance formation from the pressure peak position to the low-pressure fluid side
Solution Approach 1:
The dimple structure is divided into distinct functional zones with different geometric characteristics: a cavitation formation region on the upstream side closer to the low-pressure fluid side, and a positive pressure generation region on the downstream side closer to the high-pressure fluid side. Each region has optimized local geometry to perform its specific function while minimizing adverse effects.
Solution Approach 2:
The dimple configuration employs asymmetric positioning of the cavitation formation region and positive pressure generation region within each dimple structure. The cavitation formation region is positioned closer to the low-pressure fluid side while the positive pressure generation region is positioned closer to the high-pressure fluid side, creating an asymmetric pressure distribution that controls fluid flow direction and reduces excessive dynamic pressure generation.
2Volume of moving object
If the distance from the pressure peak position of the dynamic pressure generation region to the low-pressure fluid side is reduced, then the dimple structure becomes more compact, but leakage occurs due to insufficient pressure gradient control
Solution Approach 1:
The dimple structure is divided into distinct functional zones with different geometric characteristics: a cavitation formation region on the upstream side closer to the low-pressure fluid side, and a positive pressure generation region on the downstream side closer to the high-pressure fluid side. Each region has optimized local geometry to perform its specific function while minimizing adverse effects.
3Reliability
If a pumping action against pressure is used to push back leaked fluid to the high-pressure side, then leakage can be prevented when pressure difference is small, but the leakage amount increases when pressure difference is large
Solution Approach 1:
The dimple structure utilizes changes in pressure parameters and fluid flow characteristics to achieve sealing. By creating a cavitation formation region on the upstream side and a positive pressure generation region on the downstream side, the structure adapts to varying pressure differences through natural fluid dynamics rather than mechanical pumping action.
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 reduces fluid leakage by smoothing fluid movement and decreasing pressure gradients, while maintaining effective lubrication and sealing across different pressure conditions, improving the overall performance and efficiency of the sliding component.
Implementation Method 1
a cavitation formation region on an upstream side of each dimple is disposed closer to a low-pressure fluid side and a positive pressure generation region on a downstream side is disposed closer to a high-pressure fluid side, the fluid is sucked in the cavitation formation region
Implementation Method 2
liquid has a higher viscosity than gas, so a dynamic pressure effect is obtained due to fine waviness and roughness irregularity of the faces
Implementation Method 3
an edge on the low-pressure fluid side of the positive pressure generation region is formed into a tapered shape inclined with respect to rotating direction of the other sealing face toward the high-pressure fluid side from the low-pressure fluid side and is smoothly connected to an edge on the low-pressure fluid side of the cavitation formation region
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
To provide a sliding component smoothing fluid movement from a cavitation formation region on the upstream side of dimples formed on a sealing face to a positive pressure generation region on the downstream side. The sliding component is characterized in that: a plurality of dimples 10 are provided independently in the circumferential direction on one sealing face of a pair of sliding components relatively sliding to each other, a cavitation formation region 10a on an upstream side of each dimple 10 is disposed closer to a low-pressure fluid side and a positive pressure generation region 10b on a downstream side of each dimple is disposed closer to a high-pressure fluid side, and an edge 10d on the low-pressure fluid side of the positive pressure generation region 10b is formed into a tapered shape inclined with respect to the rotating direction of the other sealing face toward the high-pressure fluid side from the low-pressure fluid side and is smoothly connected to an edge on the low-pressure fluid side of the cavitation formation region 10a.