Piston Step Space Fuel Deflection for Emission Reduction
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Solution Overview
Problem
Direct-injection, self-igniting internal combustion engines face challenges in reducing soot and nitrogen oxide emissions due to suboptimal fuel injection patterns, leading to increased soot entry into engine oil and local peak temperature formation.
Innovation Solution
The method involves directing injection jets at the step space of the piston to create three combustion fronts, with a third combustion front forming between injection jets where residual oxygen is available, reducing soot emissions and nitrogen oxide formation by coordinating jet cone angle, start of injection, and injection duration to ensure significant fuel impinges on the step space, and using deflection means to guide fuel subsets effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If injection jets are directed at the piston recess edge area, then fuel distribution is achieved, but soot emissions increase and nitrogen oxide formation increases
Solution Approach 1:
The injection jet is segmented into three distinct subsets by directing it at the step space: a first subset deflected into the piston recess, a second subset deflected across the piston crown into the combustion chamber, and a third subset deflected circumferentially where adjacent subsets meet and redirect radially inwards. This segmentation allows each subset to burn in zones with appropriate oxygen availability, reducing soot formation.
Solution Approach 2:
The step space of the piston acts as an intermediary structure that mediates the interaction between the injection jet and the combustion chamber. By impinging the injection jet on the step space, the patent creates a controlled deflection mechanism that distributes fuel to multiple locations optimally, preventing direct contact that would cause excessive soot and nitrogen oxide formation.
2Quantity of substance
If injection jets are directed at the piston recess edge area, then fuel injection is achieved, but nitrogen oxide formation increases due to local peak temperatures
Solution Approach 1:
The fuel injection is segmented into multiple subsets that burn at different times and locations. The third subset, which forms a combustion front between adjacent injection jets, burns with a time lag relative to other combustion fronts, reducing local peak temperatures and thereby reducing nitrogen oxide emissions.
3Object-generated harmful factors
If recirculated exhaust gas is used to reduce nitrogen oxides, then nitrogen oxide emissions decrease, but fuel and oxygen mixing is insufficient
Solution Approach 1:
The step space of the piston features a curved, concave geometry that enhances the mixing of recirculated exhaust gas with oxygen and fuel. The curved surfaces promote turbulent flow patterns and better integration of the exhaust gas into the combustion mixture, ensuring adequate mixing even with high levels of recirculated exhaust gas.
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 soot emissions and nitrogen oxide formation by optimizing fuel injection patterns, promoting soot post-oxidation and better mixing of recirculated exhaust gas with oxygen and fuel, thereby minimizing local temperature peaks.
Implementation Method 1
The injection jets are guided to the step room and deflected there in such a way that a first subset of fuel is deflected in an axial direction and a radial direction into the piston recess. A second subset of fuel is deflected in the axial direction and the radial direction across the piston crown into the combustion chamber, while a third subset of fuel is deflected in a circumferential direction
Implementation Method 2
This forms between the injection jets and thus exactly where there is still enough residual oxygen available for combustion. As a result, soot emissions are reduced. Since this third combustion front burns with a time lag in relation to the other two combustion fronts, the local peak temperature in the combustion chamber and, as a result, the formation of nitrogen oxides are reduced
Implementation Method 3
If the internal combustion engine is operated with recirculated exhaust gas to reduce nitrogen oxides, the double deflection of the fuel particles in the step chamber - i.e. a first deflection in the circumferential direction and then a second deflection radially inwards - results in an additional mixing effect, which also causes the almost inert exhaust gas that is recirculated better mixed with oxygen and fuel
Data Source
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Figure 7~8
AI summary
The invention relates to a method for operating a direct-injection, self-striking internal combustion engine, and a correspondingly configured internal combustion engine. Into a piston head (5) of the piston (2), a piston recess (6) is formed, which passes into an essentially ring-shaped staging chamber (7) in the transition region of the piston head (5). Injection jets (9, 9') of an injection unit (8) are fed to the staging chamber (7) and there diverted in such a way that a first partial quantity (11) of fuel is diverted into the piston recess (6) in an axial direction (14) and a radial direction (15), that a second partial quantity (12) of fuel in the axial direction (14) and the radial direction (15) is diverted into the combustion chamber (4) via the piston head (5), and that a third partial quantity (13) of fuel is diverted into a circumferential direction (16), wherein each of the three partial quantities (13, 13') of adjacent injection jets (9, 9') meet together in the circumferential direction (16) and are subsequently diverted inwards in the radial direction (15).