Internal Combustion Engine Multi-Stage Fuel Injection
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Solution Overview
Problem
Existing methods for controlling combustion in internal combustion engines, such as single and split fuel injections, often result in high noise levels or increased NOx and soot emissions due to premature auto-ignition and insufficient air-fuel mixing time.
Innovation Solution
A method involving a first fuel injection after -15 crank angle degrees before top dead centre and a second injection approximately 10 degrees after the start of the first, with adjustable amounts and timings based on engine conditions to delay auto-ignition and enhance mixing, reducing noise and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single injection is used to fuel the combustion chamber, then fuel efficiency is improved, but noise level increases due to rapid fuel combustion
Solution Approach 1:
The fuel injection process is segmented into multiple injections rather than a single injection. The patent applies this by implementing a first injection at an earlier timing and a second injection at a later timing, distributing the total fuel quantity across separate injection events. This segmentation reduces the peak combustion rate and associated noise while maintaining overall fuel efficiency.
Solution Approach 2:
A preliminary (first) fuel injection is performed before the main combustion event to prepare the combustion chamber. The first injection occurs at an earlier crank angle position, allowing some fuel to be pre-combusted or mixed with air, thereby reducing the intensity and noise of the subsequent main combustion from the second injection.
2Object-affected harmful factors
If a split injection strategy with a small early injection is used, then noise is reduced, but temperature rises and auto-ignition is advanced, reducing mixing time and increasing emissions
Solution Approach 1:
The invention carefully adjusts the timing parameters and fuel quantities of the first and second injections to optimize the balance between noise reduction and emissions control. By controlling the crank angle positions and injection durations, the system achieves lower noise without premature temperature rise that would cause advanced auto-ignition and increased emissions.
Solution Approach 2:
The fuel injection is performed in periodic intervals with a specific time separation between the first and second injections. This periodic action allows the combustion chamber to cool and mix air-fuel between injections, preventing continuous temperature rise and maintaining optimal conditions for complete combustion with reduced emissions.
3Object-generated harmful factors
If auto-ignition is delayed to provide sufficient mixing time, then emissions are reduced, but combustion stability may be affected
Solution Approach 1:
By segmenting the fuel injection into two distinct phases, the system achieves both delayed auto-ignition for improved mixing and maintained combustion stability. The first injection establishes initial combustion conditions, while the second injection ensures complete fuel oxidation, together providing stable combustion with reduced emissions.
Solution Approach 2:
The control system uses feedback from engine operating conditions to dynamically adjust the timing and quantity of the first and second injections. This feedback mechanism ensures that auto-ignition is delayed sufficiently for mixing while maintaining the stability required for reliable combustion, adapting to varying engine loads and temperatures.
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 reduces engine noise and emissions by allowing sufficient air-fuel mixing while delaying auto-ignition, improving fuel efficiency and combustion stability across varying operating conditions.
Implementation Method 1
fuel is injected into the combustion chamber and mixes with air near the auto-ignition temperature of the fuel to form a substantially homogeneous air-fuel mixture
Implementation Method 2
Combustion of the air-fuel mixture occurs during compression when the temperature of the combustion chamber exceeds the auto-ignition temperature of the air and fuel mixture
Implementation Method 3
Combustion of the air-fuel mixture occurs during compression when the temperature of the combustion chamber exceeds the auto-ignition temperature of the air and fuel mixture
Data Source
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AI summary
A method is disclosed for operating an internal combustion engine 10 having a combustion chamber 30 with a piston 36. The internal combustion engine 10 is capable of injecting fuel into the combustion chamber 30 several times during a cycle. The method comprises performing a first fuel injection after approximately minus 25 crank angle degrees after top dead centre and performing a second fuel injection less than approximately 25 crank angle degrees after the start of the first fuel injection.