Ion Current Bias Generator PCB

Have completed the ion current bias generator PCB. Need to source components.

Ion Current Bias Generator

Research on ion current sampling and producing the bias voltage has led me to design a circuit I think should work to make around 100V across the spark gap after ignition. This design uses the back EMF from the coil primary winding after ignition to charge a capacitor in parallel with a zener diode to the bias voltage. The excess is allowed to discharge away to ground through the zener.

Test board almost ready

The simulator test board is now mostly complete. The Freescale ECU requires the software to be written and the wiring could be tidied up. The motor controller which drives the spin bench also operates at a particular frequency which produces a sharp whine. The frequency could be changed to take this out of audible frequency and make testing more tolerable.

Sparking

Today we tried out the coil and rudimentary ignitor on the test board. With a frequency generator we were able to successfully generate a spark across our large gapped plug. Unfortunately when i decided to increase the frequency the ballast resistors in series with the transistors overheated and burnt out. Now we at least know the coil and spark plug work. A new ignitor needs to be made with a better electronic switch. Currently two TIP120s in parallel are used with ballast resistors to prevent current favouring one transistor over the other, which is definitely not ideal. A design featuring an IGBT or similar will eliminate the second transistor and ballast resistor and be able to handle the EMF spikes much better.

Week 3

This week we have been designing and acquiring components to build our engine simulator.
I have designed an adaptor to mount a toothed ABS ring on a radiator fan motor in Solidworks. This will provide the simulated crankshaft sensor signal for the engine simulator. I will machine the adaptor from aluminium this week but we also need to source an ABS sensor to pick up the signal. Once this is complete we can begin assembling to simulator and wiring it up.

Spin Bench Assembly.

Adaptor diagram.

Week 2

This week we have finalised our project. We plan to develop a control system. Initially for a single cylinder motorbike engine. It will incorporate water injection and ion sensing ignition feedback to adapt the ignition timing.
Max Pike has joined our team, a third man will be good as we have a lot of work to do. Steve Liggett has approved our proposal and already sourced a Freescale ECU development kit for us to use on our test engine.
Our first task is to build a engine simulator on a bench top so we can program and test the ECU and develop our project components before moving over to testing on a real engine. This will hopefully be ready to power up and begin programming over the next week or two.

09/08/2011

OK so I've finally gotten around to creating my own blog. This is a first for me but should be interesting to look back upon as the semester progresses.
I have teamed up with Ambar for the technology project. We have both had an initial burst of energy and have almost completed the proposal for our project. We are looking at ways to improve engine performance under adverse conditions including auxiliary injection and an adaptive control system. Because of this we have asked Steve Liggett to be our technical advisor.
All very exciting stuff for me at the moment. I am looking forward to completing our proposal and getting into the technical stuff.