Glow Ignition Detection via Crankshaft Deceleration Gradient
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Solution Overview
Problem
Conventional knock sensors in internal combustion engines are unable to detect glow-ignition events, which cause undesired high maximum pressures in the cylinder, as they do not generate noticeable pressure peaks.
Innovation Solution
A method that monitors the crankshaft speed deceleration gradient during the compression stroke to detect glow-ignition by comparing the deceleration gradient to a predetermined threshold, using a crank position sensor and target wheel, and calculates the deceleration gradient over a significant portion of the deceleration phase to differentiate between normal and abnormal combustion modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a knock sensor is used to detect abnormal combustion, then combustions producing noticeable vibration patterns can be detected, but glow-ignition events cannot be detected because they do not generate detectable pressure peaks or vibrations
Solution Approach 1:
The invention changes the detection parameter from vibration amplitude (knock sensor) to crankshaft speed deceleration gradient. By monitoring the rate of change of crankshaft speed during the compression stroke, the system can detect glow-ignition events that do not produce vibrations but do cause abnormal deceleration patterns.
Solution Approach 2:
The invention replaces the mechanical vibration-based knock sensor detection with an electronic monitoring system that measures crankshaft speed variations. This substitution enables detection of glow-ignition by capturing speed deceleration gradients rather than relying on vibration patterns.
2Measurement precision
If the deceleration gradient is calculated over a short time window, then the response time is fast, but the measurement accuracy decreases; if calculated over a long time window, then measurement accuracy improves, but the response time increases
Solution Approach 1:
The invention implements a dynamic detection window that adapts to the combustion phase. The evaluation window is positioned to capture the critical deceleration period during compression stroke, optimizing both accuracy and response time by focusing measurement on the most informative time interval rather than using fixed long or short windows.
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
Effectively identifies glow-ignition events by determining a steep deceleration gradient, allowing for early detection and prevention of potential engine damage from abnormal combustion pressures.
Implementation Method 1
the sensor is arranged to detect the passage of the teeth, generating a corresponding sensor signal with a pulse train
Implementation Method 2
glow-ignition occurs when the combustion is initiated in a cylinder by a hot spot or an incandescent particle before the normal spark
Implementation Method 3
glow-ignition generates undesired high maximum pressure in the cylinder
Data Source
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AI summary
A method for monitoring glow ignition in an internal combustion engine comprises: monitoring a crankshaft speed of said engine over a detection window corresponding to a crankshaft deceleration phase related to a compression stroke in a given engine cylinder; determining a glow indicator based on a crankshaft speed deceleration gradient between two points defined by their respective crankshaft speed and crank angle, wherein the first point (Pinit) is defined by a predetermined crankshaft angle and corresponding speed during said deceleration, and the second point (Pmin) is a point of lowest speed reached during said deceleration; comparing the glow indicator to a predetermined threshold in order to detect presence or absence of glow ignition.