Pre-ignition Detection Using Crankshaft Angular Acceleration Integration

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Solution Overview

Problem

Existing pre-ignition detection methods for internal combustion engines are complex, impractical, and ineffective for real-time monitoring, especially with anti-knocking fuels like methanol, ethanol, and natural gas, due to limitations in sensor effectiveness and signal response speed.

Innovation Solution

A method that integrates instantaneous angular accelerations within a feature window, using a 58-tooth speed sensor, and applies a simple algorithm with pre-processing techniques like double moving average and tooth-picking methods to detect pre-ignition without additional devices, allowing for accurate detection in both bench tests and real vehicle environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If knocking sensor is used for pre-ignition detection, then detection coverage is improved, but detection effectiveness deteriorates for anti-knocking fuels

Engineering Contradiction:

Improvedetection coverageVSAvoiddetection effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the mechanical vibration-based knocking sensor with an electrical signal processing system using existing onboard sensors (58-tooth speed sensor, cooling water temperature sensor) to detect pre-ignition through rotational speed fluctuations and temperature changes, eliminating the fuel-type limitation of knocking sensors

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces intermediate parameters (rotational speed fluctuations, cooling water temperature changes) as mediators to indirectly detect pre-ignition conditions, allowing detection across different fuel types without requiring direct combustion analysis

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If cooling water temperature sensor is used for pre-ignition detection, then cost is reduced, but signal response speed deteriorates

Engineering Contradiction:

ImprovecostVSAvoidsignal response speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent performs preliminary processing on the cooling water temperature sensor signals using moving average filters and derivative calculations to extract pre-ignition indicators earlier in the combustion cycle, compensating for the inherent slow response of temperature sensors

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts the detection thresholds and processing parameters based on real-time engine operating conditions, enabling the system to respond quickly to pre-ignition events while maintaining cost-effectiveness through software-based adaptation

Inventive Principle:

Principle #15Dynamics

3Device complexity

If existing onboard sensors are used for pre-ignition detection, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidmeasurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent merges signals from multiple existing onboard sensors (58-tooth speed sensor, cooling water temperature sensor) and combines multiple detection indicators through signal processing algorithms to achieve high measurement precision without adding specialized detection devices

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10809155B2Method for detecting pre-ignition of internal combustion engine

Publication Date: 2020.10.20 TSINGHUA UNIVERSITY

AI summary

The invention relates to a method for detecting the pre-ignition of an internal combustion engine comprising: integrating all instantaneous angular accelerations in a feature window to acquire integral values, and judging whether the internal combustion engine is pre-ignited according to the integral values and an pre-ignition threshold in a detection window; the feature window is an angle range corresponding to a top dead center of the compression stroke of the internal combustion engine to 3-5 consecutive signal teeth backward from the top dead center along the rotating direction of a crankshaft; the instantaneous angular accelerations correspond to the signal teeth in the feature window in a one-to-one manner. The method for detecting the pre-ignition of the present application is simple in algorithm and small in amount of calculation, only 3-5 pieces of data in the feature window are required to be numerically integrated, and the abnormal combustion is determined without complicated time-frequency analysis and vibration information reconstruction cylinder pressure; the structure of the internal combustion engine may not need to be modified and the marketization period is short; since the 58-tooth speed sensor is one of the basic configurations of the internal combustion engine, no additional device needs to be added and thus low cost is achieved; and the method has high detection accuracy for both steady-state and transient conditions and also has a good application prospect for the real vehicle environment.