Igniter Off-State Dead-Time Circuit Prevents Spark Noise
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Solution Overview
Problem
The existing igniter systems experience premature cut-off due to spark noise, where residual charge in the high-frequency filter causes the judgment signal to be falsely asserted, leading to repeated switching of the switch element even after the ignition signal has gone low.
Innovation Solution
Incorporating an off-state dead-time circuit that prohibits the switch element from turning off during a predetermined dead time after the judgment signal transitions to a negated level, using a mask signal generating circuit and logic gate to maintain the switch element in an off state during this period, thereby preventing false triggering by spark noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high-frequency filter is used to remove noise from the ignition signal, then high-frequency noise is suppressed, but residual charge in the filter causes false judgment signals after ignition
Solution Approach 1:
The dead-time circuit is activated in advance at the moment of ignition to prevent false triggering. By proactively disabling the judgment signal during the critical period when residual charge in the filter could cause false positives, the system eliminates the reliability issue before it can manifest.
Solution Approach 2:
The dead-time circuit acts as an intermediary between the high-frequency filter and the judgment signal generation. It mediates the conflict by blocking the problematic residual charge signal from reaching the judgment logic, allowing both the filter to function and false signals to be prevented.
2Speed
If the switch element is turned off immediately when the ignition signal goes low, then switching speed is maximized, but spark noise causes premature cut-off and repeated switching
Solution Approach 1:
The dead-time circuit applies preliminary anti-action by preventing the switch element from turning off during the critical period after ignition. This counteracts the harmful effect of spark noise that would otherwise cause premature cut-off, ensuring the switch remains in the desired state despite noise interference.
Solution Approach 2:
The system dynamically adjusts the switch control by introducing a time-dependent dead period. During this dynamic window after ignition, the normal switching response is suspended, allowing the system to adapt to the transient noise conditions that exist immediately after spark generation.
3Reliability
If an off-state dead-time circuit is introduced to prevent false triggering, then switching stability is improved, but device complexity increases
Solution Approach 1:
The dead-time circuit functionality is merged with the existing switch control apparatus rather than being implemented as a separate external component. By integrating the dead-time control logic into the existing control structure, the patent achieves improved switching stability while minimizing the increase in overall device complexity.
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
This solution effectively prevents cut-off occurrences immediately after ignition, ensuring stable operation by masking noise-induced transitions and maintaining the switch element in an appropriate state, thus preventing abnormal ignition.
Implementation Method 1
the judgment stage 300A is provided with a high-frequency filter 303 that removes high-frequency noise superimposed on the ignition signal IGT
Implementation Method 2
A voltage comparator 302 compares the voltage level VFIL of the ignition signal IGT that has passed through the high-frequency filter 303 with a predetermined reference voltage (threshold value) VREF
Implementation Method 3
When the switch element 202 is turned off, which cuts off the current IL1 that flows through the primary coil L1. In this stage, the primary coil L1 generates a primary voltage VL1 (=L·dIL1/dt) of several hundreds of V which is proportional to a temporal differentiation of the current IL1. In this state, the coil L2 generates a secondary voltage VS of several tens of kV
Implementation Method 4
This provides a discharge of the spark plug 106, thereby providing combustion of the mixture gas stored in the engine 110
Data Source
AI summary
An igniter includes a switch element and a switch control apparatus. An ignition signal IGT is input to an input line of the switch control apparatus. A high-frequency filter removes high-frequency noise from the input line. A voltage comparator compares an output voltage VFIL of the high-frequency filter with a reference voltage VREF, so as to generate a judgment signal SDET. A driving stage controls an on/off switching operation of the switch element according to the judgment signal SDET. An off-state dead-time circuit prohibits the switch element from turning off during a predetermined dead time after the judgment signal SDET transits to a negated level that corresponds to the off state of the switch element.