Rotary Engine Seal Shielding Elastomer From Combustion Heat
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Solution Overview
Problem
Rotary internal combustion engines face challenges in sealing combustion chambers due to high pressure and thermal loads, leading to leakage of combustion gases and coolant, with existing metallic seals experiencing carbon buildup and reduced effectiveness over time.
Innovation Solution
A housing assembly for rotary engines featuring a seal with an elastomeric member and a thermoset plastic shield, where the thermoset plastic member protects the elastomeric member from combustion gases and maintains sealing effectiveness by circumferentially overlapping the combustion region, using materials like polybenzimidazole for high temperature resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic seals are used to seal combustion chambers, then sealing effectiveness is initially good, but carbon buildup occurs over time reducing sealing effectiveness
Solution Approach 1:
The seal is constructed as a composite structure with a metallic shield providing structural support and a running surface, and an elastomeric member providing sealing compliance. This composite design prevents carbon buildup on the elastomeric sealing surface while the metallic shield maintains structural integrity under high pressure and temperature conditions.
Solution Approach 2:
The elastomeric member acts as an intermediary between the metallic shield and the combustion chamber surfaces. It provides a compliant sealing surface that resists carbon buildup while the metallic shield protects against mechanical failure, mediating between the conflicting requirements of compliance and structural strength.
2Reliability
If seals are placed at the interface between rotor housing and housing, then sealing of combustion chambers is achieved, but the seal is subjected to high pressure and thermal loads
Solution Approach 1:
The seal combines a metallic shield with high temperature and pressure resistance with an elastomeric member that provides sealing compliance. The metallic shield protects the elastomeric material from direct exposure to the harshest thermal and mechanical loads while maintaining sealing effectiveness.
Solution Approach 2:
The seal design changes the material parameters by using different materials with complementary properties at different radial positions. The metallic shield handles high temperature and pressure parameters, while the elastomeric member handles sealing compliance requirements, optimizing performance under extreme conditions.
3Ease of manufacture
If a single-material seal is used, then manufacturing is simple, but the seal cannot simultaneously withstand high temperature, high pressure, and maintain compliance
Solution Approach 1:
The seal is manufactured as a composite component with a metallic shield and an elastomeric member bonded together. This composite construction maintains manufacturing simplicity through integrated production methods while achieving the versatility needed to withstand high temperature, high pressure, and maintain sealing compliance simultaneously.
Solution Approach 2:
The composite seal structure provides multi-functionality: the metallic shield provides structural strength and temperature resistance, while the elastomeric member provides sealing compliance and pressure resistance. This universal design handles multiple demanding conditions that a single material could not address alone.
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 seals combustion chambers, preventing leakage and protecting the elastomeric member from thermal and mechanical stress, while maintaining sealing integrity and reducing carbon buildup, thus enhancing engine performance and durability.
Implementation Method 1
a shield disposed radially inwardly of the elastomeric member relative to the rotation axis and in contact with both the housing and the rotor housing, the shield including a thermoset plastic member extending along at least a portion of a perimeter of the groove and axially overlapping the elastomeric member
Implementation Method 2
an elastomeric member; and a shield disposed radially inwardly of the elastomeric member
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A housing assembly (12) for a rotary internal combustion engine has: a rotor housing (18) extending around a rotation axis and from a first side to a second side, and having an inner face; a housing (11) secured to the first side; and a seal (70) received within a groove (16B) at an interface between the rotor housing (18) and the housing (11), the groove (16B) extending around a perimeter of the first side and located radially outwardly of the inner face, the seal (70) including: an elastomeric member; and a shield disposed inwardly of the elastomeric member and in contact with both the housing (11) and the rotor housing (18), the shield including a thermoset plastic member extending along at least a portion of a perimeter of the groove (16B) and axially overlapping the elastomeric member, the thermoset plastic member circumferentially overlapping a combustion region of a rotor cavity (20) where combustion occurs during operation of the rotary internal combustion engine.