Apex Seal Arrangement for Rotary Engine
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Solution Overview
Problem
Existing sealing arrangements in rotary internal combustion engines, such as Wankel engines, face reduced longevity due to direct contact between springs and seals, leading to inefficiencies in maintaining the seal against the peripheral wall.
Innovation Solution
A rotor assembly with a radial groove and an apex seal that moves radially between positions, featuring a biasing member and a platform that interfaces with a shoulder in the groove, ensuring proper sealing and reducing wear by trapping the biasing member even if the apex seal fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring is placed in direct contact with an underside of a seal to bias the seal against the peripheral wall, then the seal maintains contact pressure, but the sealing arrangement longevity is reduced
Solution Approach 1:
The patent introduces an intermediary platform between the spring and the seal. The spring biases the platform, which in turn biases the seal against the peripheral wall. This intermediate structure prevents direct contact between the spring and seal, reducing wear on the seal while maintaining the necessary contact pressure for effective sealing.
2Ease of manufacture
If the groove width is uniform throughout its depth, then manufacturing is simpler, but the platform cannot effectively trap the biasing member when the seal reaches the first position
Solution Approach 1:
The patent employs an asymmetric groove design where the groove width varies with depth. The groove has a first width at the radial outer position and a second width at the radial inner position, with the second width being greater than the first width. This asymmetric configuration allows the platform to trap the biasing member effectively when the seal reaches the first position, preventing the biasing member from escaping, while still being manufacturable.
3Device complexity
If the apex seal is allowed to travel freely without a platform, then the device complexity is reduced, but the biasing member may escape and sealing effectiveness is compromised
Solution Approach 1:
The patent divides the sealing arrangement into distinct functional segments: the apex seal, the platform, and the biasing member. The platform is positioned between the seal and the biasing member, creating a segmented structure that allows each component to perform its specific function. This segmentation enables the platform to trap the biasing member and maintain sealing effectiveness while keeping the overall device complexity manageable.
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 enhances the longevity of the sealing arrangement by preventing the biasing member from escaping and maintaining effective sealing pressure, thereby improving the engine's operational integrity.
Implementation Method 1
a biasing member biasing the apex seal toward the second position
Data Source
AI summary
A rotor assembly for a rotary internal combustion engine is provided. The rotor assembly includes a rotor having a radial groove defined radially in a peripheral surface of the rotor. The groove has a depth and an intermediate shoulder at an intermediate depth. The groove has a first width therealong that is narrower than an intermediate width at the shoulder. An apex seal is received in the groove and protrudes from the peripheral face of the rotor. The apex seal is configured to move radially between a first position and a second position outward of the first position. A biasing member biases the apex seal toward the second position. A platform is disposed in the groove between the apex seal and the biasing member and has a width greater than the first width.