Misfire Detection Using Engine Speed Sensor Signatures

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Solution Overview

Problem

Existing misfire detection methods for reciprocating piston engines are inadequate due to the need for multiple sensors, lack of accuracy in transient operations, and inability to identify the cause of misfire, especially in low-speed-low-load regions, which leads to inefficiencies and increased downtime.

Innovation Solution

A system utilizing an engine crankshaft speed sensor to detect misfires by evaluating engine speed signatures and decelerations, allowing for accurate identification of potential valve issues and misfire causes without requiring additional sensors, and enabling detection during transient operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple sensors (exhaust manifold pressure, exhaust manifold temperature, accelerometers) are used for misfire detection, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvemisfire detection accuracyVSAvoidnumber of sensors

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The existing engine speed sensor is made multi-functional by programming the controller to perform both engine speed measurement and misfire detection using the same sensor signal, eliminating the need for additional dedicated misfire sensors

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The controller is made multi-functional by having it perform both engine control and misfire detection algorithms using the same engine speed sensor input, consolidating diagnostic capabilities within the existing control system

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Difficulty of detecting and measuring

If exhaust manifold pressure based misfire detection is used, then misfire detection capability is improved, but reliability deteriorates in low speed-low load regions

Engineering Contradiction:

Improvemisfire detection capabilityVSAvoiddetection reliability in low speed-low load regions

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The detection approach changes from exhaust manifold pressure parameters to engine speed signature parameters, which remain reliable and detectable across all operating conditions including low speed-low load regions where pressure-based methods fail

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If steady state operation or specific operating routines are required for misfire detection, then measurement precision is improved, but productivity decreases due to interference with desired engine operation

Engineering Contradiction:

Improvemisfire detection accuracyVSAvoidengine operation efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The misfire detection system transitions from static steady-state requirements to dynamic transient capability, using real-time engine speed signature analysis that adapts to changing operating conditions without requiring the engine to leave its desired operating mode

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Misfire detection operates continuously during all engine operation including transient conditions, eliminating the need to interrupt or alter engine operation for diagnostic purposes, thereby maintaining continuous productivity

Inventive Principle:

Principle #20Continuity of useful action

4Difficulty of detecting and measuring

If existing misfire detection proposals are used, then misfire detection capability is improved, but loss of information occurs as cause identification requires service technician correlation of multiple data points

Engineering Contradiction:

Improvemisfire detection capabilityVSAvoidcause identification information

Core Design Contradiction:

Difficulty of detecting and measuringVSLoss of information

Solution Approach 1:

The system provides immediate feedback by analyzing engine speed signatures to not only detect misfire events but also identify their causes (injector malfunction, airflow malfunction, compression malfunction), delivering complete diagnostic information automatically without requiring external technician interpretation

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11920535B2Apparatuses, methods, systems, and techniques of misfire detection using engine speed sensor

Publication Date: 2024.03.05 CUMMINS INC

AI summary

A system includes a reciprocating piston engine configured to output torque to drive a load. The system includes an engine speed sensor operatively coupled with the engine and configured to output an engine speed signal. The system includes an electronic control system operatively coupled with the powertrain. The electronic control system is configured to determine an engine acceleration in response to the engine speed signal, and detect a misfire of the engine in response to the engine acceleration.