Engine Ignition Control Unit Misfire Detection via Speed Variation
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Solution Overview
Problem
In gasoline combustion engines, igniters without abnormality detection circuits cannot detect spark plug malfunctions due to mounting restrictions, and the use of such circuits increases the igniter's cost.
Innovation Solution
An engine ignition device with a control unit that generates an ignition signal and includes an engine speed variation detector, determining misfires and igniter abnormalities based on engine speed thresholds, allowing for abnormality detection without an abnormality detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an abnormality detection circuit is added to the igniter, then the detection capability of spark plug malfunction is improved, but the cost of the igniter increases
Solution Approach 1:
The patent introduces an intermediary detection method by measuring the secondary winding current through the existing primary current measurement circuit. Instead of adding a separate detection circuit, the system uses the primary winding current as an indirect indicator to infer secondary winding status and spark plug health, thereby achieving detection capability without increasing igniter cost
Solution Approach 2:
The existing primary current measurement circuit serves dual purposes: both controlling ignition timing and detecting abnormality. The system leverages the already-present current sensing capability to monitor ignition system health, eliminating the need for dedicated detection hardware and reducing manufacturing costs while maintaining reliability
2Reliability
If an abnormality detection circuit is added to the igniter, then the detection capability of spark plug malfunction is improved, but the mounting restriction is increased
Solution Approach 1:
The primary current measurement circuit is designed to perform multiple functions: ignition control timing and abnormality detection. By making the circuit universal, the patent eliminates the need for separate detection components, thereby improving detection capability while reducing mounting restrictions and simplifying the overall igniter structure
Solution Approach 2:
The patent merges the detection function with the existing current measurement circuit. Instead of combining separate detection components, the system integrates abnormality detection capability into the primary control circuit by analyzing the relationship between primary and secondary winding currents, thereby reducing device complexity and mounting restrictions
3Reliability
If the primary current is increased to improve ignition reliability, then the spark energy is improved, but the energy loss increases
Solution Approach 1:
The patent dynamically adjusts the primary current based on real-time detection of ignition requirements. By continuously monitoring the secondary winding current and comparing it with predetermined thresholds, the system optimizes primary current levels to achieve reliable ignition while minimizing energy loss, rather than using a fixed high current level
Solution Approach 2:
The system changes the current parameter dynamically based on detected conditions. When abnormality is detected (secondary current below threshold), the control unit adjusts primary current supply accordingly, allowing optimal energy efficiency while maintaining ignition reliability under different operating conditions
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
Enables cost-effective detection of misfires and igniter malfunctions, reducing the need for additional circuits and mounting restrictions, while identifying problematic cylinders for maintenance.
Implementation Method 1
a spark plug that is provided for each cylinder is connected to an igniter, and the spark plug is energized by turning on and off the primary electric current to a primary winding of the igniter thereby to generate a high voltage in a secondary winding of the ignition coil
Data Source
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AI summary
An ignition device of an engine includes a control unit and an igniter including an ignition coil having a primary and a secondary winding. Supply and stop of a current to the primary winding are performed based on the ignition signal to generate high voltage in the secondary winding thereby to cause a spark to a spark plug provided for a cylinder of the engine. The control unit includes an engine speed variation detector that detects an engine speed variation. The control unit determines a misfire occurs in the cylinder when the engine speed variation is at or higher than a first threshold and smaller than a second threshold that is greater than the first threshold. The control unit determines an abnormality occurs in the igniter in the cylinder when the engine speed variation is at or higher than the second threshold.