Fredrik soldering the circuit board for the ignition module
Not everyone in Team Baldos is a final-year master’s student. Fredrik is one of these exceptions; he already holds a bachelor’s degree in automotive engineering. Done with his thesis in electrical valve controls, he is back in school again to reach master level.
While doing this he was assigned a project by Johan to construct an ignition module for a small engine. This happened to be our engine, and middle of February Max introduced him in a project group meeting, and afterwards he became another member of the Team. Since then he’s been involved in several subprojects – he’s helped Kristofer and Erika with the computer nodes, Max and Sebastian with the ECU, and Jonas with ICU testing – but his primary concern has remained the ignition module for both ICE:s.
An ignition module might seem like overcomplicating a standard feature in cars. Most often the sparks appear whenever the cylinder has reached a specific position; creating that kind of system is fairly simple, and Fredrik’s ignition module does that as well. But to build a truly efficient vehicle requires a little more effort.
Janne, Daniel, Harald and Sebastian testing Skilži on our improvised dynamometer
Now, apart from creating sparks, our ignition module repeatedly measures the ionization level in the combustion compartment. This is done to determine when, during the cycle, the cylinder pressure reaches its maximum. The trick is to get the maximum cylinder pressure to coincide with the exact instant for when the piston is most responsive to impact (around 14 degrees after TDC, for those interested). What makes the whole thing so tricky is that there’s a delay between ignition and maximum pressure, and to compensate for the delay the ignition module continuously shifts the spark time back and forth.
Talking about time – this all happens extremely fast. Doing 6500 revolutions per minute, the interval within which the module can adjust the spark is about 4 microseconds. To get the whole thing right Fredrik’s system does about 120 thousand measurements per second. As seen, the project requires high-quality electrical components, like those supplied to us by McXpress.
The finished printed circuit board in Baldos II
Another thing to consider is a phenomenon called pre-ignition. This happens whenever the fuel-air mix ignites before the spark has fired. This often occurs because of a too high cylinder pressure or hot spots in the combustion chamber. Pre-ignition is harmful to the engine, and therefore the ignition module is designed to detect the phenomenon and automatically compensate for it.
When working with such extreme tolerance levels there’s a need to keep things in order and under control. Fredrik has developed a habit for checking, double checking and triple checking so that everything fits together and works as it should. There are other reasons for that than maintaining engine performance. A casual spark is at around 40 000 Volts, and although the amperage is rather small there’s no telling what will happen if it reaches a human finger. Fredrik has so far done a good job in avoiding this.
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