Opposed Piston Aircraft Engine Harmonic Cam Layout
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Solution Overview
Problem
Traditional aircraft engines with turbojet and turboprop systems face challenges with high shaft temperatures, leading to increased costs due to expensive bearing systems and cooling requirements, and in-line piston systems experience excessive vibration and weight due to asymmetrical designs and material reinforcement.
Innovation Solution
The implementation of an axial-cylinder, opposed-piston engine layout with harmonic cams and a driveshaft supported by bearings, where pistons reciprocate in opposite directions, reducing vibration and allowing for lighter materials like plastics and ceramics, and eliminating the need for heavy reinforcement by maintaining a closed circuit of forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional turbofan engines use long drive shafts extending through the core engine to connect turbines and compressors, then power transmission is achieved, but shaft temperatures become excessively high requiring expensive bearing systems and cooling systems
Solution Approach 1:
The patent divides the single long drive shaft into multiple separate drive shafts, each confined to a specific thermal zone. The first drive shaft connects the first turbine to the first compressor within the first thermal zone, while the second drive shaft connects the second turbine to the second compressor within the second thermal zone. This segmentation eliminates the need for a single long shaft traversing hot zones, thereby reducing shaft temperatures and eliminating expensive cooling systems while maintaining effective power transmission.
2Stability of the object's composition
If in-line piston systems use asymmetrical crankshaft designs with counterweights, then piston motion is balanced, but lateral forces cause significant vibration and require heavier reinforcement
Solution Approach 1:
The patent employs opposed pistons within each cylinder that move symmetrically in opposite directions, creating a balanced system where lateral forces cancel each other out. This symmetrical opposed-piston configuration eliminates the need for asymmetrical crankshaft designs with counterweights, thereby reducing vibration while maintaining piston motion balance.
Solution Approach 2:
The opposed piston arrangement acts as its own counterbalance system. As one piston moves in one direction, the other piston moves in the opposite direction, creating natural counterbalancing forces that offset lateral vibrations without requiring additional counterweights or heavy reinforcement.
3Strength
If crankshaft components are made of stronger, heavier materials with increased dimensions, then resistance to lateral forces is improved, but engine weight increases
Solution Approach 1:
The opposed-piston configuration creates symmetrical force distribution that eliminates lateral forces, removing the need for heavy reinforced crankshaft components. The system achieves the required strength through balanced force cancellation rather than material reinforcement.
Solution Approach 2:
The patent converts the potentially harmful lateral forces into beneficial balanced forces by using opposed pistons. The forces that would normally require heavy reinforcement are transformed into counterbalancing actions that reduce overall stress on components, enabling lighter materials to be used.
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 design reduces engine vibrations, lowers weight, and allows for the use of lighter materials, enhancing efficiency and reducing operational costs by maintaining balanced forces and minimizing heat transfer, making it suitable for aircraft applications.
Implementation Method 1
a cam follower assembly (26) engaged to a cam (18) having a curvilinear shaped shoulder (138)
Implementation Method 2
into which fuel may be injected by a fuel injector (34)
Data Source
AI summary
An aircraft engine has a hollow driveshaft with a spool coaxial with the driveshaft and extending through the driveshaft to rotate independently of the driveshaft. A first harmonic cam is mounted on the driveshaft and a second spaced apart harmonic cam is mounted on the spool. At least one combustion cylinder is positioned between the cams along a combustion cylinder axis that is parallel with but radially spaced apart from the driveshaft. A piston assembly is disposed in each end of the combustion cylinder, with each piston assembly engaging a separate cam. A high-pressure compressor turbine is mounted on the driveshaft and driven by movement of a piston assembly, compressing air for the combustion cylinder. A rotating component is mounted on the spool and driven by movement of the other piston assembly. The rotating component may be another compressor turbine, a drive turbine, a fan or a propeller.