Engine Auxiliary Combustion Chamber Asymmetric Piston Wall
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Solution Overview
Problem
Existing engines face difficulties in igniting lean air-fuel mixtures during lean-burn operations due to the challenges of fuel injection and ignition plug placement in the cylinder head, leading to reduced ignitability.
Innovation Solution
The engine design incorporates an auxiliary combustion chamber formed by a head partition wall and a piston partition wall with tapered portions, where the injector's injection hole is exposed outside the head partition wall, allowing for efficient fuel injection into the auxiliary combustion chamber, creating a richer air-fuel mixture that can be easily ignited by the ignition plug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the injector's injection hole is disposed inside the head partition wall, then the fuel injection efficiency into the auxiliary combustion chamber is improved, but the mounting difficulty of the injector and ignition plug increases
Solution Approach 1:
Instead of disposing the injection hole inside the head partition wall as in conventional designs, this patent inverts the arrangement by exposing the injection hole outside the head partition wall. This allows the injector and ignition plug to be mounted more easily on the outer surface of the cylinder head, reducing mounting difficulty while still enabling effective fuel injection into the auxiliary combustion chamber through the tapered piston partition wall structure.
2Ease of manufacture
If the injection hole is exposed outside the head partition wall, then the ease of mounting the injector and ignition plug is improved, but the fuel injection efficiency into the auxiliary combustion chamber deteriorates
Solution Approach 1:
The patent employs asymmetric design in the piston partition wall with a tapered structure that is inclined relative to the cylinder axis. The tapered surface is configured to guide fuel from the injection hole (located outside the head partition wall) into the auxiliary combustion chamber. This asymmetric tapering compensates for the reduced direct access to the auxiliary combustion chamber, maintaining fuel injection efficiency while allowing easy mounting of the injector.
Solution Approach 2:
The piston partition wall is designed with different surface characteristics: a tapered surface facing the injection hole to facilitate fuel guidance, and a substantially cylindrical outer surface for structural integrity. This local differentiation of surface quality optimizes both fuel injection efficiency and mounting ease in different regions of the piston partition wall.
3Ease of manufacture
If a conventional piston partition wall with uniform height is used, then the manufacturing simplicity is improved, but the ignitability in lean-burn deteriorates
Solution Approach 1:
The piston partition wall transitions from a conventional uniform-height design to an asymmetric tapered design. The tapered surface is inclined at a specific angle relative to the cylinder axis, creating varying heights across the piston partition wall surface. This asymmetric geometry optimizes the air-fuel mixture distribution in the auxiliary combustion chamber, improving ignitability during lean-burn operations while remaining manufacturable through standard machining processes.
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 configuration improves ignitability during lean-burn operations by ensuring the air-fuel ratio in the auxiliary combustion chamber is at the theoretical ratio, facilitating efficient combustion and reducing the likelihood of misfires.
Implementation Method 1
an ignition plug (46) disposed in the cylinder head (14)
Implementation Method 2
an injector (44) disposed in the cylinder head (14) and having an injection hole (66a, 68a) exposed outside the head partition wall (50)
Implementation Method 3
The engine burns the air-fuel mixture in the auxiliary combustion chamber, thereby improving the ignitability in lean-burn
Data Source
AI summary
An engine includes a cylinder head, an ignition plug disposed in the cylinder head, a head partition wall disposed on the cylinder head to surround a periphery of the ignition plug, an injector disposed in the cylinder head and having an injection hole exposed outside the head partition wall, a cylinder block coupled to the cylinder head, a cylinder formed in the cylinder block, a piston disposed in the cylinder, and a piston partition wall disposed on a crown surface of the piston to face the head partition wall in a sliding direction of the piston. The height of the piston partition wall from the crown surface on the side closer to the injector is less than the height of the piston partition wall from the crown surface on the side farther from the injector.