Liquid Fuel Injection for Engine Knock Control
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Solution Overview
Problem
Internal combustion engines using the Otto cycle face issues with engine knock and pre-ignition due to increased compression ratios, leading to sub-optimal combustion and efficiency, as the temperature rise during compression can cause damaging effects.
Innovation Solution
Condensing fuel into its liquid phase through a refrigeration process and injecting it into the engine's combustion chamber during the compression stroke, where it vaporizes, absorbing heat and limiting temperature rise, allowing for higher compression ratios without engine knock or pre-ignition, and enabling better fuel-air mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compression ratio in the cylinder is increased to improve engine efficiency, then the efficiency is improved, but the temperature of the air/fuel mixture increases causing engine knock or pre-ignition
Solution Approach 1:
The patent applies phase transition by injecting fuel in liquid form during the compression stroke, where it vaporizes and absorbs heat (latent heat of vaporization), limiting the temperature rise caused by compression and preventing engine knock and pre-ignition
Solution Approach 2:
The patent changes the physical state parameter of the fuel from gaseous (conventional) to liquid (invention), and controls the timing of fuel injection during the compression stroke to alter the thermal parameters of the air/fuel mixture, enabling higher compression ratios without harmful effects
2Temperature
If fuel is injected in liquid form during compression stroke, then temperature rise is limited and higher compression ratios are enabled, but additional refrigeration equipment is required
Solution Approach 1:
The liquid fuel serves a dual function: it is both the working substance for combustion and the refrigerant that cools the air/fuel mixture during vaporization, eliminating the need for separate refrigeration equipment and making the system self-sufficient
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 approach allows for higher compression ratios without engine knock or pre-ignition, improves fuel-air mixing, reduces compression work, and enhances engine efficiency by ensuring the fuel is already in a gaseous form for combustion, thus eliminating the need for additional gasification.
Implementation Method 1
the latent heat of vaporisation of the fuel as it vaporises
Implementation Method 2
the fuel vaporises into its gaseous phase during a compression stroke
Implementation Method 3
a fuel which has been condensed into its liquid phase via a refrigeration process
Data Source
AI summary
A method of operating an internal combustion engine comprising a cylinder and a piston, the method including injecting into the cylinder, as a liquid, a fuel which has been condensed into its liquid phase via a refrigeration process, such that the fuel vaporises into its gaseous phase during a compression stroke of the piston and before combustion such that a rise in temperature caused by the compression stroke is limited by the absorption of heat by the fuel.