Stepped Oil Seal Pumping Grooves for Rotary Engine Leakage Control
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Solution Overview
Problem
Conventional oil seals in rotary engines fail to completely prevent shear leakage and pressure leakage due to relative motion and centrifugal forces, especially at higher engine RPMs.
Innovation Solution
A sealing device with an oil seal member featuring a circumferentially extending step on its sliding face, where one radial side has a high surface with pumping grooves to direct oil from the high surface to the low surface, reducing leakage by utilizing the step and pumping grooves to manage oil flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oil seals are used with simple scraping action, then the structure is simple, but shear leakage and pressure leakage cannot be completely prevented
Solution Approach 1:
The sliding face is segmented into multiple functional zones: a high surface, a low surface, and pumping grooves connecting them. This segmentation allows different regions to perform different functions - the high surface receives oil, the pumping grooves actively transport oil against leakage forces, and the low surface directs oil flow - thereby preventing both shear leakage and pressure leakage more effectively than a simple scraping surface.
Solution Approach 2:
Different regions of the sliding face are given different properties and functions. The high surface has specific geometric characteristics to receive oil, the pumping grooves have optimized dimensions and orientations to maximize pumping effect, and the low surface has features to guide oil flow. This local differentiation of properties enhances overall sealing performance while managing oil flow dynamics.
2Productivity
If the rotor rotates at high speed, then productivity increases, but pressure leakage due to centrifugal force increases
Solution Approach 1:
The pumping grooves are designed to preemptively counteract centrifugal force effects before they can cause significant pressure leakage. By creating positive pressure zones within the pumping grooves that act in opposition to centrifugal force, the system prepares for high-speed operation conditions and maintains sealing effectiveness even as engine RPM increases.
Solution Approach 2:
The design converts the harmful effect of centrifugal force into a beneficial pumping action. The relative motion between the sliding face and stationary-side member, which would normally cause shear leakage, is harnessed to drive oil through the pumping grooves from the low surface back to the high surface, creating a beneficial pumping effect that counteracts pressure leakage.
3Reliability
If the oil seal member slides relative to the stationary-side member, then sealing function is achieved, but shear leakage occurs due to relative motion
Solution Approach 1:
The relative sliding motion between the oil seal member and stationary-side member, which normally causes shear leakage, is converted into a beneficial pumping action. The pumping grooves are designed to utilize this relative motion to actively pump oil from the low surface back to the high surface, transforming the harmful shear leakage mechanism into a useful oil return mechanism that enhances sealing performance.
Solution Approach 2:
The pumping grooves function as hydraulic elements that utilize fluid pressure and flow dynamics to pump oil against the direction of leakage. By creating pressure differentials and utilizing the viscosity of oil, the grooves actively transport oil from the low-pressure side back to the high-pressure side, counteracting shear leakage through hydraulic principles.
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 prevents shear leakage and pressure leakage, enhancing the sealing performance by actively pumping oil back into the high-pressure side, thereby reducing leakage rates and improving the overall sealing efficiency.
Implementation Method 1
the high surface is provided with pumping grooves to pump oil tending to leak from the high surface side into the low surface side, into the high surface side by sliding relatively to the stationary-side member
Implementation Method 2
The sliding face is provided with a step extending circumferentially, and has a relatively high surface formed on one radial side with respect to the step and a relatively low surface on the other radial side
Data Source
AI summary
An oil seal member is provided at an outside surface of a member performing whirling motion such as a rotary engine rotor. A sliding face of the oil seal member that slides relatively to a stationary-side member is provided with a step extending circumferentially, and has a relatively high surface formed on one radial side with respect to the step and a relatively low surface on the other radial side. The high surface is provided with pumping grooves to pump oil tending to leak from the high surface side into the low surface side, into the high surface side by sliding relatively to the stationary-side member.