Linear Free Piston Engine Gas Linkage Work Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional slider-crank reciprocating engines face limitations in achieving high compression/expansion ratios due to mechanical stresses and heat transfer issues, while linear free piston combustion engines struggle to efficiently convert kinetic energy to mechanical or electrical work.
Innovation Solution
A linear free piston combustion engine with indirect work extraction via a gas linkage, featuring two opposed free pistons and extractor pistons connected to a rotary or linear electromagnetic machine, allowing for large and variable compression and expansion ratios with minimal time spent at top dead center, utilizing gas linkages to translate forces without mechanical linkages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional slider-crank reciprocating engines are used, then mechanical linkages provide reliable work extraction, but compression ratios are limited to 8-24 due to mechanical stress and heat transfer issues
Solution Approach 1:
The patent removes the mechanical linkage (connecting rod and crankshaft) from the piston assembly, allowing the piston to move freely without mechanical constraints. This extraction enables compression ratios above 30 by eliminating the mechanical stress limitations that constrain conventional engines to 8-24 compression ratios.
Solution Approach 2:
The patent introduces a linear electromagnetic machine as an intermediary between the free piston and the work extraction system. This mediator converts the piston's kinetic energy to electrical energy without requiring direct mechanical linkages, thereby enabling high compression ratios without overwhelming mechanical stresses.
2Use of energy by moving object
If compression ratio is increased in conventional engines, then theoretical efficiency increases, but heat transfer from combustion chamber increases due to larger surface-to-volume ratio at TDC
Solution Approach 1:
The patent employs dynamic piston motion where the free piston accelerates and decelerates naturally under pressure and inertial forces, spending minimal time at TDC. This dynamic approach reduces heat transfer losses while maintaining high compression ratios, as the piston quickly passes through the high-temperature region rather than lingering there.
Solution Approach 2:
The patent changes the piston motion parameters by eliminating mechanical linkage constraints, allowing the piston to achieve higher velocities and shorter dwell times at TDC. This parameter change reduces the time available for heat transfer to occur, thereby reducing heat loss while maintaining high compression ratios for improved theoretical efficiency.
3Ease of operation
If slider-crank mechanism is used, then piston position is controlled, but piston acceleration at TDC is reduced compared to free piston
Solution Approach 1:
The patent extracts the mechanical linkage (slider-crank mechanism) that constrains piston motion, allowing the piston to become a free piston that accelerates under pressure and inertial forces alone. This removal enables higher piston acceleration at TDC compared to slider-crank mechanisms, while position control is achieved through electromagnetic forces from the linear electromagnetic machine.
4Use of energy by moving object
If free piston is used with direct electromagnetic conversion, then kinetic energy is converted to electrical energy, but temperature control of translator and magnetic losses occur
Solution Approach 1:
The patent introduces a gas linkage as an intermediary between the free piston and the extractor piston connected to the electromagnetic machine. This gas-filled chamber acts as a thermal buffer, isolating the translator of the electromagnetic machine from the high temperatures in the combustion chamber, thereby enabling temperature control and reducing magnetic losses.
5Force
If mechanical linkages are used for work extraction, then forces are transmitted directly, but mechanical stresses overload components at high compression ratios
Solution Approach 1:
The patent replaces the mechanical linkage system with a linear electromagnetic machine that converts piston kinetic energy to electrical energy. This substitution eliminates mechanical stresses on components like piston pins, piston rods, and crankshafts, thereby improving reliability at high compression ratios while still enabling force transmission through electromagnetic interactions.
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 enables high-efficiency conversion of chemical energy to electrical energy, achieving indicated-work efficiencies of 60% and minimizing mechanical and frictional losses, while maintaining a large volume at top dead center to reduce heat transfer.
Implementation Method 1
each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston
Implementation Method 2
each extractor piston is connected to a rotary electromagnetic machine
Implementation Method 3
linear free piston combustion engine
Data Source
AI summary
Various embodiments of the present invention are directed toward a linear free piston combustion engine with indirect work extraction via gas linkage, comprising: a cylinder with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction; two opposed extractor pistons disposed in their own cylinders at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and two gas linkages, each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston; wherein each extractor piston is connected to a rotary electromagnetic machine.