Ignition Device Ion Current Diagnosis Signal Multiplexing
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Solution Overview
Problem
Conventional ignition control systems for internal combustion engines face issues with increased complexity and harness numbers due to dedicated terminals for failure diagnosis signals, leading to inaccurate ignition signal transmission and stability problems when using ion currents as diagnosis signals.
Innovation Solution
An ignition device with an ignition coil, switching element, waveform shaping circuit, ion current detecting means, and ion signal generating means that uses the ion current as a failure diagnosis signal, allowing stable ignition signal supply and detection without complicating the device structure by outputting the ion signal after the conduction signal is turned off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated terminal is provided for outputting failure diagnosis signals, then failure diagnosis capability is improved, but device complexity and number of harnesses increase
Solution Approach 1:
The signal wire originally dedicated to ignition signals is made multi-functional by enabling it to carry both ignition signals and failure diagnosis signals (ion current) through time-division multiplexing. The waveform shaping circuit invalidates the conduction signal during the ion current output period, allowing the same wire to serve dual purposes without signal interference, thus eliminating the need for a dedicated failure diagnosis terminal and reducing harness complexity
Solution Approach 2:
The time domain is segmented into distinct periods: an ignition signal output period and an ion current output period. During the ion current output period, the conduction signal is invalidated to prevent simultaneous output of ignition and failure diagnosis signals. This temporal segmentation allows the same signal wire to carry different types of signals at different times, resolving the contradiction between diagnostic capability and system complexity
2Reliability
If ion current is output as failure diagnosis signal during ignition signal transmission, then failure diagnosis capability is improved, but ignition signal transmission accuracy deteriorates
Solution Approach 1:
The time domain is divided into separate periods for ignition signal transmission and ion current output. The waveform shaping circuit controls the conduction signal to be valid only during the ignition signal period, and invalidates it during the ion current output period. This temporal segmentation prevents signal interference and ensures accurate transmission of both ignition signals and failure diagnosis signals without compromising either
Solution Approach 2:
The waveform shaping circuit proactively invalidates the conduction signal before the ion current output period begins, preventing any potential interference between ignition signals and ion current. This preliminary action ensures that the signal wire is ready to carry ion current without residual ignition signal interference, maintaining transmission accuracy
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 stable supply and detection of ignition signals and failure diagnosis using ion currents without increasing the system's complexity, ensuring reliable control and accurate signal transmission.
Implementation Method 1
an ignition coil having a primary coil and a secondary coil; a switching element for causing a primary current to be conducted through and shut off from the primary coil of the ignition coil
Implementation Method 2
ion current detecting means connected to the secondary coil of the ignition coil, for detecting an ion current flowing through the secondary coil
Data Source
AI summary
An ignition device, including: an ignition coil (1) having a primary coil and a secondary coil; a switching element (5) for causing a primary current to be conducted through and shut off from the primary coil of the ignition coil; a waveform shaping circuit (6) for shaping a waveform of an ignition signal transmitted from an outside through a signal line to supply a conduction signal thus obtained to the switching element; ion current detecting means (8, 9) connected to the secondary coil of the ignition coil, for detecting an ion current flowing through the secondary coil; and ion signal generating means (10, 11, 12) for outputting an ion signal, which indicates the ion current detected for a predetermined period after the conduction signal of the waveform shaping circuit has been turned off, to the outside through the signal line while invalidating the conduction signal from the waveform shaping circuit.