Piston Ring Pocket Structure for Low-Speed Pre-Ignition Mitigation
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Solution Overview
Problem
Current piston assemblies in internal combustion engines fail to effectively mitigate Low-Speed Pre-Ignition (LSPI) caused by oil droplets igniting in the combustion chamber, leading to pressure spikes and potential engine damage.
Innovation Solution
A piston assembly design featuring a piston head with an annular groove and a piston ring that defines angularly spaced pockets to receive and manage oil, with the piston ring's inner diameter surface and annular surface cooperating to direct oil into these pockets, reducing the likelihood of premature ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If piston assemblies are designed for turbocharged direct-injection vehicles, then power output is improved, but Low-Speed Pre-Ignition occurs due to oil droplet accumulation in the combustion chamber
Solution Approach 1:
The piston head features an annular groove and multiple pockets positioned to intercept and collect oil droplets before they can accumulate in the combustion chamber and cause pre-ignition. This preliminary action of capturing oil prevents the harmful effect from occurring in the first place
Solution Approach 2:
The invention extracts the harmful oil droplets from the combustion chamber environment by providing dedicated collection pockets that remove oil from the air-fuel mixture space, preventing it from causing pre-ignition events
2Reliability
If oil is present in the combustion chamber, then lubrication is provided, but oil droplets can ignite prematurely causing pressure spikes and engine damage
Solution Approach 1:
The piston head is segmented with multiple discrete pockets (at least three) distributed around the annular groove to collect and contain oil droplets in separate locations, preventing accumulation and premature ignition while maintaining necessary lubrication
3Reliability
If the piston ring is designed to slide against the cylinder wall, then sealing and lubrication are improved, but oil can be deposited into the combustion chamber
Solution Approach 1:
The annular groove and pockets act as an intermediary structure between the piston ring/cylinder wall interface and the combustion chamber, capturing oil that would otherwise be deposited into the combustion chamber while allowing the piston ring to maintain its sealing and lubrication functions
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
The design effectively reduces the occurrence of LSPI by containing and managing oil within the pockets, thereby minimizing the risk of oil droplets igniting and causing pressure spikes, thus protecting engine components from damage.
Implementation Method 1
The inner diameter surface of the piston ring and the annular surface of the piston head cooperate with one another to define a plurality of pockets angularly spaced from one another about the longitudinal axis and configured to receive oil
Implementation Method 2
the peripheral surface is adapted to slide against a wall of the cylinder in response to the piston head reciprocating along the longitudinal axis
Data Source
AI summary
A piston assembly for an internal combustion engine of a motor includes a piston head having an outer diameter surface spaced a first distance from the longitudinal axis and an annular surface spaced a second distance from the longitudinal axis, with the second distance being less than the first distance. Upper and lower walls extend between the annular surface and the outer diameter surface so as to define an annular groove in the outer diameter surface. A piston ring is received within the annular groove and includes an inner diameter surface facing the annular surface of the piston head. The inner diameter surface of the piston ring and the annular surface of the piston head cooperate with one another to define a plurality of pockets angularly spaced from one another about the longitudinal axis and configured to receive oil.