Spark Ignition Fuel Injection Control via Flash Boiling
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Solution Overview
Problem
In internal combustion engines, the existing fuel injection timing control methods do not consider flash boiling, leading to inefficiencies in fuel efficiency and increased particulate matter and number emissions, as they either cause fuel to adhere to the piston crown or result in reduced penetration of fuel sprays.
Innovation Solution
A fuel injection device that determines the tip end portion fuel temperature and adjusts the fuel injection timing based on flash boiling conditions, advancing the timing when flash boiling occurs for top injection types and retarding it for side injection types to optimize air-fuel mixture properties and prevent particulate matter issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel injection timing is advanced during intake stroke, then fuel efficiency is improved, but fuel adheres to piston crown causing pool combustion and increased particulate matter emissions
Solution Approach 1:
The patent changes the physical state parameter of fuel by heating it to high temperature before injection. This temperature parameter change causes flash boiling upon injection, which fundamentally alters the fuel spray behavior and prevents adhesion to the piston crown, thereby resolving the contradiction between advanced injection timing and particulate matter emissions
Solution Approach 2:
The patent utilizes phase transition from liquid to vapor through flash boiling. When high-temperature fuel is injected into the low-pressure cylinder, instantaneous vaporization occurs, causing the fuel spray to spread widely and preventing liquid fuel from adhering to the piston crown, thus enabling advanced injection timing without increasing particulate matter emissions
2Manufacturing precision
If fuel is injected at high pressure through narrow spray, then fuel atomization is improved, but fuel spray penetration is reduced and may not reach optimal combustion zone
Solution Approach 1:
The patent employs phase transition from liquid to vapor through flash boiling to increase fuel spray penetration. The instantaneous vaporization expands the fuel spray cone angle and extends the penetration distance, allowing the fuel to reach the optimal combustion zone while maintaining good atomization quality from the high-pressure injection
3Device complexity
If conventional fuel injection timing control is used without considering flash boiling, then system complexity is minimized, but fuel efficiency cannot be optimized across different operating conditions
Solution Approach 1:
The patent changes the fuel temperature parameter to high temperature to induce flash boiling, which fundamentally alters fuel spray characteristics. This parameter change enables the system to achieve optimized fuel efficiency across different operating conditions without requiring complex control mechanisms, as the flash boiling effect naturally adjusts spray behavior based on operating conditions
Solution Approach 2:
The patent utilizes the self-service principle where the heated fuel automatically undergoes flash boiling upon injection into the low-pressure cylinder. This self-regulating phase transition process naturally adjusts fuel spray characteristics according to operating conditions without requiring external control intervention, thereby maintaining system simplicity while optimizing fuel efficiency
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 enhances fuel efficiency by extending the allowable range of fuel injection timing and reducing particulate matter emissions by ensuring proper vaporization and spray distribution, while maintaining optimal combustion characteristics.
Implementation Method 1
instantaneous boiling of the fuel, namely, so-called flash boiling, occurs
Implementation Method 2
at least a part of the fuel is vaporized and expanded instantaneously
Implementation Method 3
promote vaporization of fuel liquid drops, and reduce the penetration of each fuel spray
Data Source
AI summary
A spark ignition internal combustion engine includes: intake and exhaust valves disposed at a ceiling part of a combustion chamber; and a fuel injection valve including a tip end portion including injection holes, and being structured to inject fuel through the injection holes toward a crown of a piston, wherein the tip end portion of the fuel injection valve is arranged in a region of the ceiling part surrounded by the intake and exhaust valves. A fuel injection control includes: determining a tip end portion fuel temperature directly or indirectly, which is a temperature of fuel at the tip end portion of the fuel injection valve; and setting a fuel injection timing advanced, in response to a condition that the tip end portion fuel temperature is higher than a temperature threshold value, wherein the temperature threshold value relates to flash boiling of fuel at the injection holes.