I have learned a lot over the past two weeks and as a result I have made a lot of changes towards my approach of measuring volume displacement of the Stirling engine. Before I get into it I will first mention that I have updated my Project Timeline in accordance with my current progress. I have had a long set back due to the first engine not being able to work as intended.
I have put together list of specifications about the engine.
I mentioned previously that I was testing a selected spring to confirm whether it was suitable for driving my hall effect position sensor. After numerous test I have decided that this approach is bad because the spring consumed valuable engine output power in order to function. I then tested time of flights and linear magnetic sensors. The outcomes were the sensors were either too big to integrate with the engine or they had too low of a sample rate.
After much trial and error I then found a clever way of monitoring the power pistons' linear displacement by predicting its' velocity and position from measuring the flywheel revolution.
Seeing as the flywheel was fixed to the camshaft, which is fixed to the Power piston, one revolution of the flywheel then would equate to one full piston cycle from top dead centre (TDC) and back.
I positioned a digital hall effect sensor to detect when the piston was at TDC. The single reading was able to provide flywheel rpm and piston position.
The rest of the work was done in Labview. The idea works great as long as the rpm remains constant for some time, as my prediction is always one cycle behind. That is OK though because the engine accelerates slowly. This solves the issue of consuming engine output power to control other sensors.
Here is a demonstration of process working.
I have put together list of specifications about the engine.
I mentioned previously that I was testing a selected spring to confirm whether it was suitable for driving my hall effect position sensor. After numerous test I have decided that this approach is bad because the spring consumed valuable engine output power in order to function. I then tested time of flights and linear magnetic sensors. The outcomes were the sensors were either too big to integrate with the engine or they had too low of a sample rate.
After much trial and error I then found a clever way of monitoring the power pistons' linear displacement by predicting its' velocity and position from measuring the flywheel revolution.
Seeing as the flywheel was fixed to the camshaft, which is fixed to the Power piston, one revolution of the flywheel then would equate to one full piston cycle from top dead centre (TDC) and back.
I positioned a digital hall effect sensor to detect when the piston was at TDC. The single reading was able to provide flywheel rpm and piston position.
The rest of the work was done in Labview. The idea works great as long as the rpm remains constant for some time, as my prediction is always one cycle behind. That is OK though because the engine accelerates slowly. This solves the issue of consuming engine output power to control other sensors.
Here is a demonstration of process working.
Currently, I am working on incorporating pressure measurements. I will be using a different sensor than originally specified because the working pressure of this new engine is much lower.
Basic ABP Series, Compensated/Amplified, gage, leadless SMT AN: single axial barbed port, dry gases only, no diagnostics, 0 psi to 1 psi, digital I²C address: 0x28, no temperature output, no sleep mode, 5.0 Vdc.
Apart from the pressure readings, I will also be looking into temperature and external power consummations as awell as adding some hardware for cooling the top of the engine because sensors are positioned there.
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