Crankcase Pressure Control for Engine Knock Prevention
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Solution Overview
Problem
Premature ignition in internal combustion engines, particularly in downsized and supercharged spark-ignition engines, occurs due to high compression temperatures and the transport of lubricating oil constituents into the combustion chamber, leading to increased cylinder pressures and potential engine damage.
Innovation Solution
Adjusting the crankcase pressure to prevent the transport of lubricating oil constituents into the combustion chamber by creating a negative pressure range of 100-700 mbar relative to ambient air, using a vacuum from the inlet manifold or compressor, and adjusting the ignition point to induce knocking combustion to remove deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high compression ratios and high supercharging rates are used to reduce fuel consumption, then fuel efficiency is improved, but premature ignition occurs due to high compression temperatures
Solution Approach 1:
The patent applies preliminary anti-action by detecting the tendency for premature ignition in advance (before it occurs) and taking preventive measures. The system calculates the tendency to premature ignition based on angular velocity profile and combustion focal point, then preemptively injects additional fuel or adjusts ignition timing to prevent the harmful ignition event before it can occur.
Solution Approach 2:
The patent performs preliminary action by preparing the combustion chamber conditions in advance of the problematic operating range. The system pre-calculates the combustion focal point and tendency to premature ignition, and pre-adjusts fuel injection or ignition timing parameters before the engine enters the critical speed range where premature ignition is likely to occur.
2Reliability
If additional fuel is injected to prevent premature ignition, then combustion stability is improved, but fuel consumption increases
Solution Approach 1:
The patent applies partial action by injecting only the necessary additional fuel quantity required to prevent premature ignition, rather than continuously injecting excess fuel. The system calculates the precise additional fuel amount needed based on the detected tendency to premature ignition, combustion focal point position, and current operating conditions, thereby minimizing the fuel penalty while maintaining combustion stability.
Solution Approach 2:
The patent changes operational parameters dynamically based on real-time engine conditions. The system adjusts fuel injection quantity, ignition timing, and other parameters according to the calculated tendency to premature ignition and combustion focal point, optimizing the balance between preventing premature ignition and minimizing additional fuel consumption.
3Productivity
If engine speed is increased to improve productivity, then output is improved, but premature ignition becomes more likely in the 1500-2500 rpm range
Solution Approach 1:
The patent implements feedback by continuously monitoring engine operating parameters (angular velocity profile, combustion focal point, cylinder pressure) and using this information to adjust fuel injection and ignition timing in real-time. The system calculates the tendency to premature ignition based on current conditions and immediately adjusts control parameters to prevent premature ignition while maintaining engine output.
Solution Approach 2:
The patent applies dynamics by making the fuel injection and ignition timing systems adjustable and responsive to changing operating conditions. The system dynamically modifies injection quantities, timing, and other parameters based on the detected tendency to premature ignition and combustion focal point position, allowing the engine to maintain high output while adapting to conditions that predispose to premature ignition.
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
Prevents premature ignition by reducing the transport of lubricating oil constituents and deposits into the combustion chamber, thereby minimizing engine wear and maintaining efficient combustion processes.
Implementation Method 1
adjusting a pressure in the crankcase of the internal combustion engine such that a transport of lubricating oil constituents from the crankcase to a combustion chamber of a cylinder due to a pressure ratio between the crankcase and the combustion chamber
Implementation Method 2
internal combustion engines, especially spark-ignition engines, are being made smaller and supercharged by a compressor, for example a turbocharger
Implementation Method 3
uncontrolled ignition processes of a cylinder charge more or less significantly in advance of the planned ignition point
Data Source
AI summary
Methods for preventing a premature ignition of a cylinder charge in advance of a planned ignition point in an internal combustion engine are provided. In one method, a pressure in a crankcase of the internal combustion engine is adjusted so as to prevent lubricating oil constituents from being transported from the crankcase to a combustion chamber of a cylinder of the internal combustion engine due to a pressure ratio between the crankcase and the combustion chamber. In another method, an ignition point for a cylinder of the internal combustion engine is adjusted in a given operating range of the internal combustion engine in such a way that the adjusted ignition point brings about a knocking combustion in the cylinder. Internal combustion engines having a device for preventing a premature ignition of a cylinder charge in advance of a planned ignition point are also provided.