Ignition Coil Soft Shutdown via Dual Counter Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ignition systems face issues with overheating and damage due to prolonged dwell times caused by ECU malfunctions, where the soft shutdown period is delayed by supply voltage fluctuations, leading to increased risk of ignition coil damage.
Innovation Solution
The implementation of a dual counter system that controls a reference current to initiate a soft shutdown of the ignition coil independently of supply voltage and temperature, ensuring a linear reduction in coil current through a digital-to-analog converter and clock signal frequency adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional soft shutdown function is used to prevent ignition coil damage during over dwell conditions, then the ignition coil is protected from overheating, but the shutdown is delayed due to time-lag caused by supply voltage fluctuations, increasing the risk of damage
Solution Approach 1:
The patent replaces the conventional voltage-dependent soft shutdown mechanism with a timing-based control system using counters and clock signals. Instead of relying on voltage levels to trigger shutdown, the system uses a predetermined time threshold (M counts) from a first counter to initiate shutdown, ensuring consistent and timely protection regardless of supply voltage fluctuations.
Solution Approach 2:
The patent changes the control parameter from voltage-based to time-based. By using a clock signal with fixed frequency and counting cycles, the system establishes a predetermined shutdown threshold that is independent of supply voltage. The reference current linearly decreases based on clock cycles rather than voltage levels, eliminating the time-lag issue.
2Reliability
If the soft shutdown period is extended to ensure complete current reduction, then the ignition coil is fully protected, but the overall dwell time increases, reducing system efficiency
Solution Approach 1:
The patent implements a dynamic shutdown process where the reference current linearly decreases over time rather than an abrupt cutoff. The second counter generates a linearly decreasing reference current that ramps down the coil current smoothly, balancing protection requirements with system efficiency. The shutdown duration is precisely controlled by clock cycles, optimizing both protection and efficiency.
3Reliability
If the shutdown threshold is set to activate early to prevent damage, then the ignition coil is protected, but normal operation may be interrupted prematurely, reducing productivity
Solution Approach 1:
The patent uses feedback from the first counter to monitor the actual dwell time and compare it against the predetermined threshold (M counts). The ECU malfunction detection is based on whether the first counter reaches the threshold within the expected time window. This feedback mechanism ensures that shutdown is activated only when actual over-dwell conditions occur, preventing premature interruption of normal operation while protecting against genuine malfunctions.
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 ensures a quicker and more controlled shutdown of the ignition coil, reducing the overall time it is active and mitigating the risk of overheating, regardless of supply voltage levels, thereby protecting the ignition system from damage.
Implementation Method 1
an oscillating signal having a frequency that is a function of the supply voltage VDD
Implementation Method 2
a first counter to increment through a predetermined number of counts M in response to the clock signal CLK
Implementation Method 3
An output of the second counter controls a reference current IREF that decreases linearly over time and wherein a rate of change of the reference current may be adjusted according to a frequency of a clock signal
Implementation Method 4
An output of the second counter controls the value of a reference current that decreases linearly over time
Data Source
AI summary
Various embodiments of the present technology comprise a method and apparatus for an ignition system. In various embodiments, the ignition system activates a soft shutdown of an ignition coil in the event of an over dwell condition. The apparatus comprises a first counter and a second counter that are selectively activated at predetermined events. An output of the second counter controls the value of a reference current that decreases linearly over time and wherein a rate of change of the reference current may be adjusted according to a frequency of a clock signal. In various embodiments, the soft shutdown operates independent of the supply voltage and temperature.