Piston Crown Recess for Direct Injection Engine Combustion
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Solution Overview
Problem
Reciprocating internal-combustion engines with spark ignition and direct fuel injection face challenges in achieving reliable ignition conditions, particularly at partial load, leading to increased pollutant emissions and wear on ignition devices due to existing fuel injection methods, which either require precise geometric relationships or result in incomplete combustion and harsh combustion noises.
Innovation Solution
A reciprocating internal-combustion engine design featuring a trough-shaped recess in the piston crown with a barrel-shaped contour, guiding the fuel injection jet to minimize wall contact and enhance tumble flow turbulence, ensuring better fuel-air mixing and reduced pollutant emissions across both homogeneous and stratified-charge operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the injection jet is aimed directly at the ignition device (jet-guided method), then reliable stratified-charge operation is ensured, but the ignition device suffers from increased wear and shortened life due to direct fuel injection
Solution Approach 1:
The piston crown with its specifically shaped recess serves as an intermediary element between the fuel injection jet and the ignition device. The recess guides the fuel jet along the piston crown surface, allowing the fuel to be delivered to the ignition device indirectly rather than through direct injection, thereby reducing wear on the ignition device while maintaining reliable ignition.
2Duration of action of stationary object
If the injection jet is deflected onto the piston crown (wall-guided method), then direct injection onto the ignition device is avoided, but incomplete combustion occurs leading to increased unburned hydrocarbon and soot emissions
Solution Approach 1:
The invention changes the geometric parameters of the piston crown recess, specifically creating a barrel-shaped contour with optimized curvature and dimensions. This parameter optimization ensures that the fuel jet is guided efficiently along the piston crown surface without premature contact, allowing complete combustion and reducing pollutant emissions while still protecting the ignition device.
3Stability of the object's composition
If steeply upright intake ports are used to achieve strong charge movement, then homogeneous mixture formation is improved, but the overall engine height increases
Solution Approach 1:
Instead of relying solely on vertical intake port orientation to generate charge movement, the invention utilizes the horizontal geometry of the piston crown recess to guide the fuel jet and generate the necessary tumble flow. This dimensional shift allows effective charge movement and mixture homogenization without requiring steeply upright intake ports, thereby maintaining a compact engine height.
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 design improves combustion stability, reduces misfiring and pollutant emissions, particularly soot formation, while maintaining high flow quality and output, by imparting turbulence to the fuel-air mixture, thus optimizing ignition conditions and reducing engine wear.
Implementation Method 1
imparting turbulence to the fuel-air mixture, thus optimizing ignition conditions
Data Source
AI summary
A reciprocating internal-combustion engine having at least two gas intake ports (3) with gas intake valves (6), at least one gas exhaust port (4) with a gas exhaust valve (7) and at least one ignition device (14) per cylinder (1) is provided. The engine can also include a combustion chamber (1.1) formed by a cylinder cover (2.1) and a crown (11.1) of a piston (11). A trough-shaped recess (12) can be provided in the piston crown (11.1) and is bounded by a trough base (12.1) and side walls (16). The recess (12) can intersect a roof ridge (11.2) on the piston crown (11.1) and the trough base (12.1) slopes towards a fuel injection nozzle (8) and ends in a wall zone (12.2) extending steeply upwards on its side facing the fuel injection nozzle (8).