Ignition Coil Integrating Circuit for Pre-ignition Detection
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Solution Overview
Problem
Existing electronic ignition systems for internal combustion engines are complex and prone to false alarms due to the use of operational amplifiers and multiple electronic components in ionization current measurement circuits, which complicates the detection of pre-ignition and misfire in air-fuel mixtures.
Innovation Solution
A simplified integrating circuit using Zener diodes and capacitors to measure the integral of the ionization current, reducing computational load on the Electronic Control Unit and providing reliable detection of pre-ignition and misfire by charging and discharging capacitors during different phases of the ignition cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an integrating circuit with operational amplifier and multiple electronic components is used to measure ionization current, then measurement capability is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the integration function from a complex operational amplifier-based circuit and implements it using a simple RC integrating circuit with resistor and capacitor only. This removes unnecessary electronic components while preserving the measurement capability, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent replaces expensive and complex operational amplifier components with inexpensive passive components (resistor and capacitor) that are easier to manufacture and more reliable. This simplification reduces device complexity while maintaining the essential measurement function.
2Reliability
If a complex integrating circuit is used to detect pre-ignition and misfire, then detection capability is provided, but false alarms increase
Solution Approach 1:
The patent removes operational amplifiers and other complex active components from the integrating circuit, keeping only passive resistor and capacitor elements. This reduction in component count eliminates sources of electronic noise and failure, thereby reducing false alarms while maintaining detection reliability.
Solution Approach 2:
The RC integrating circuit uses the natural electrical properties of the resistor and capacitor to perform integration and signal conditioning without requiring external power or complex control logic. This self-service approach reduces the number of active components that could fail or generate false signals.
3Measurement precision
If operational amplifier-based integrating circuit is used, then ionization current integration is achieved, but computational load on ECU increases
Solution Approach 1:
The patent extracts the computational integration function from the ECU and implements it in the analog domain using a simple RC circuit. This physical integration occurs passively in the circuit itself, eliminating the need for the ECU to perform complex numerical integration calculations, thus reducing computational load and improving processing efficiency.
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
The solution effectively reduces the risk of false alarms and provides accurate detection of pre-ignition and misfire, with the ability to transfer measurement data efficiently to the Electronic Control Unit, enhancing engine performance monitoring.
Implementation Method 1
the Zener diode is reversely biased and it is configured to limit the voltage across the integrating capacitor during its charging to a maximum defined value equal to the Zener voltage of the Zener diode
Implementation Method 2
measuring the value of the integral of the ionization current with an integrating circuit which comprises a integrating capacitor
Implementation Method 3
the ionization current is generated by applying a potential difference to the electrodes of the spark plug and by measuring the current generated by means of the ions produced in the combustion chamber
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
It is disclosed an electronic device (1 ) to control an ignition coil of an internal combustion engine. The device comprises a high-voltage switch (4), a driving unit (5), a bias circuit (6) and an integrating circuit (7). The high-voltage switch (4) is connected in series with a primary winding of a coil and configured to switch between a closed position and an open position. The driving unit (5) is configured to control the closing of the high-voltage switch during a phase of charging (T_chg) energy into the primary winding, and is configured to control the opening of the high-voltage switch during a phase of transfer (T_tr) of energy from the primary winding to a secondary winding of the coil and during a phase of measurement (T_ion) of an ionization current (I_ion) subsequent to the phase of transfer of energy, wherein said ionization current is generated by the ions produced during the combustion process of the comburent- combustible mixture in the combustion chamber of a cylinder of the engine by means of the spark generated by a spark plug (3) in the phase of transfer of energy. The bias circuit (6) is configured to generate said ionization current (I_ion) during the phase of measurement (T_ion) of the ionization current, wherein said bias circuit is connected in series to a second terminal of the secondary winding. The integrating circuit (7) is interposed between the bias circuit and a reference voltage (GND). The integrating circuit comprises an integrating capacitor (C4) connected in series to the bias circuit (6) and connected between the bias circuit and the reference voltage. The integrating capacitor is configured, in the case wherein a pre-ignition of the comburent-combustible mixture in the combustion chamber during the phase of charging occurs (t10.2, t12), to pre-charge during the phase of charging energy in the primary winding by means of the ionization current flowing through the secondary winding (2-2) during the phase of charging (T_chg), so as to measure a value of the integral of the ionization current which flows through the secondary winding during the phase of charging due to said pre-ignition; is configured, in the case wherein the pre-ignition of the comburent- combustible mixture does not occur, to maintain the charge state substantially constant during the phase of charging energy; and is configured to completely discharge by means of the current flowing through the secondary winding during the phase of transfer (T_tr) of energy from the primary winding to the secondary winding.