Ignition Device Using Exciter Coil Voltage Timing for Engine Start
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pulserless ignition devices for internal combustion engines face challenges in accurately determining the ignition position at engine start, leading to reduced startability due to varying crankshaft rotational speeds, especially influenced by lubricant viscosity and ambient temperature, resulting in improper ignition timing and potential engine stalling.
Innovation Solution
An ignition device with an exciter coil generating AC voltage for one crankshaft rotation, an ignition capacitor charged by the positive voltage, a discharge switch, and a microprocessor-controlled power supply circuit that determines the ignition position using the time difference between first and second negative voltages to calculate the rotational speed and set the ignition timing accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulserless ignition devices use fixed ignition timing based on predetermined rotational speeds, then the device structure is simple, but the ignition timing becomes inaccurate when rotational speed varies due to lubricant viscosity and ambient temperature
Solution Approach 1:
The microprocessor measures the actual time interval between the first and second negative voltages from the exciter coil, calculates the actual rotational speed based on this measured time, and adjusts the ignition timing accordingly. This feedback mechanism allows the system to adapt to varying rotational speeds caused by lubricant viscosity and ambient temperature, achieving accurate ignition timing without requiring complex predetermined speed schedules
Solution Approach 2:
The system uses the exciter coil's own output voltages (first and second negative voltages) as the timing reference signal. By measuring the time interval between these naturally occurring voltages, the system determines rotational speed and ignition timing without requiring external sensors or additional signaling components, thereby maintaining simplicity while achieving precision
2Reliability
If the ignition timing is advanced to compensate for low rotational speed at engine start, then startability improves, but the ignition timing becomes improper and causes engine stalling when rotational speed is actually higher
Solution Approach 1:
The ignition timing is dynamically adjusted based on the actual rotational speed measured at each ignition cycle. The microprocessor continuously measures the time interval between negative voltages, calculates current rotational speed, and determines appropriate ignition timing accordingly. This dynamic adjustment allows the system to provide advanced timing when needed (improving startability) while preventing over-advancement that would cause stalling
3Ease of manufacture
If the exciter coil generates AC voltage once per crankshaft rotation with first and second negative voltages, then crank angle information can be obtained without a pulser, but the determination of ignition position becomes difficult due to varying rotational speed
Solution Approach 1:
The exciter coil serves multiple functions: it generates the ignition voltage for the ignition capacitor and simultaneously provides the timing reference signals (first and second negative voltages) for rotational speed measurement and ignition positioning. This multi-functionality eliminates the need for a separate pulser while providing sufficient information for accurate crank angle detection
Solution Approach 2:
The mechanical pulser system is replaced with an electrical timing reference system using the exciter coil's output voltages. The microprocessor measures the time interval between negative voltage peaks to determine rotational speed and calculate ignition timing, substituting mechanical position sensing with electrical timing measurement
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 enables precise determination of the ignition position at engine start, improving startability by aligning the ignition timing with the actual rotational speed, thereby stabilizing engine rotation and reducing start-related issues.
Implementation Method 1
an exciter coil that is provided in an AC generator that rotates in synchronism with the internal combustion engine, and generates an AC voltage once for one rotation of a crankshaft
Implementation Method 2
an ignition capacitor that is provided on a primary side of the ignition coil and charged to one polarity by an output of an ignition power supply
Implementation Method 3
a discharge switch that conducts when receiving an ignition signal and discharges charges accumulated in the ignition capacitor through the primary coil of the ignition coil
Data Source
AI summary
An ignition device for an internal combustion engine including: an exciter coil that generates an AC voltage having a positive half wave and first and second negative half waves generated before and after the positive half wave with rotation of the internal combustion engine; and an ignition control portion that controls an ignition position of the engine using a microprocessor to which a power supply voltage is supplied from a power supply circuit that converts the voltage having the negative half waves generated by the exciter coil to a DC voltage, wherein the ignition control portion is comprised so as to cause a timer to start a counting operation at the start of the operation of the microprocessor, regard a measurement value of the timer as time between generation of the first negative half wave and generation of the second negative half wave to arithmetically operate counting data for measuring the ignition position based on rotational speed information of the engine obtained from the time, and immediately measure the arithmetically operated counting data to generate an ignition signal.