Wankel Engine Apex Seal Spring Design for Leakage Reduction
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Solution Overview
Problem
Prior art sealing arrangements in rotary Wankel engines suffer from gaps due to manufacturing tolerances and differential thermal expansions, which compromise the efficiency of sealing working chambers.
Innovation Solution
A rotor design with axially spaced end faces and a peripheral face defining apex portions, utilizing a spring with distinct axial and radial action portions to bias apex seal members radially and axially, ensuring tight sealing between the rotor and peripheral wall, eliminating the need for intermediary seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prior art sealing arrangements are used with gaps between seal members, then manufacturing is easier and assembly is simpler, but sealing efficiency deteriorates due to fluid leakage between working chambers
Solution Approach 1:
The apex seal member is divided into multiple segments or lips that can independently contact the peripheral wall. This segmentation allows each segment to adapt to surface irregularities and thermal expansion differently, maintaining sealing contact without requiring complex intermediary sealing components between adjacent seals
Solution Approach 2:
The sealing approach transitions from relying on precise gap control in one dimension to utilizing multi-dimensional contact through the apex seal's extended structure that contacts the peripheral wall along its length, creating sealing in multiple directions simultaneously
2Reliability
If manufacturing tolerances and differential thermal expansions are not compensated, then the sealing arrangement is simpler, but gaps form between seal members compromising engine efficiency
Solution Approach 1:
The apex seal member is designed with material and geometric parameters that allow it to expand and contract in response to thermal changes. The seal's cross-sectional area, material composition, and initial positioning are specifically chosen to maintain optimal contact pressure with the peripheral wall across the operating temperature range, compensating for differential thermal expansion without requiring complex adjustment mechanisms
Solution Approach 2:
The sealing system transitions from a static gap-based design to a dynamic contact-based design where the apex seal member continuously adapts its position and contact pressure with the peripheral wall during engine operation, responding to thermal expansion, rotation speed, and load variations to maintain sealing integrity
3Reliability
If intermediary seals are used to eliminate gaps, then sealing between chambers improves, but device complexity and number of components increases
Solution Approach 1:
The apex seal member is designed to perform multiple sealing functions simultaneously. Its extended structure and contact geometry enable it to seal against the peripheral wall while also preventing fluid communication between adjacent working chambers, eliminating the need for separate intermediary seal components
Solution Approach 2:
The invention merges the functions of multiple separate seal components into a single integrated apex seal member. The seal's design combines the sealing surfaces and geometry needed to prevent leakage between chambers while maintaining contact with the rotating peripheral wall, reducing component count and assembly complexity
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 provides a robust and efficient sealing mechanism that minimizes fluid communication between working chambers, reducing leakage and enhancing engine performance by ensuring continuous contact along the rotor periphery without intermediary seals.
Implementation Method 1
each apex seal member being biased by a respective spring, each spring being an integral band
Data Source
AI summary
In one aspect, there is described a rotor of a Wankel engine including a plurality of apex seal members each biased by a respective spring, each spring including an axial action portion and a radial action portion, the axial action portion including at least two radially extending band sections with adjacent ones of the band sections being connected by a fold, one of the band sections contacting a radially extending surface of the apex seal member and another of the band sections contacting a radially extending element of the rotor body, and the radial action portion forming a major part of a length of the spring, contacting an axially extending surface of the apex seal member in two spaced apart locations, and contacting the rotor body between the two spaced apart locations.