Ion Sensing ideas and circuit designs
Posted: Wed Oct 29, 2008 7:10 pm
OK just like the Knock sensing thread this is a sponge for all of your good ideas and prospective designs that could well be used on FreeEMS in the future. I have been working on both knock sensing and ion sensing for the last 2 months and have a couple of ideas to play with.
What is Knock sensing? Well in its simplest description it is a way of monitoring the pressure within the combustion chamber in realtime.
Why the hell do we need that?
if you are asking that then you are on the wrong forum! but i'll humour you anyway :p. Detonation is lethal for an internal combustion engine it blows head gaskets to shreds, it can burn holes straight through pistons, holes in the block bend conrods and wreak all sorts of havoc of your engine. it is much more serious in forced induction engines as the "charge" in the cylinder is much more volatile. in NA engines detonation is much less common but it does happen on a lesser scale in the form of pinking/pinging or knock this is still serious and most engines won't put up with much of it before blowing a head gasket, or worse!
So in answer to the question, it would be really handy when tuning your engine and trying to get the last couple of foot pounds out of it to be able to spot trouble before it happens and correct the tune accordingly.
The theory?
The gap between the spark plug is biased to a few hundred volts DC, the current flowing across the gap through the mixture in the combustion chamber is measured. as the pressure increases the current flow increases and is measured by a sensitive front end.
A sharp spike in the pressure after the initial ignition of the mixture indicates an abnormal burn and is likely a knock event occurring. the job of analyzing the waveform is probably too complex to do with discrete logic and op amps. it is very likely that any successful project would require a dedicated micro controller with the ability to take in to account RPM, load, atmospheric humidity and Manifold Air Temp in fact most of the factors required by the XDP in FreeEMS possibly including including timing information.
So come on guys lets get some ideas on e-paper and get some cutting edge feedback signals back to the FreeEMS of the future.
What is Knock sensing? Well in its simplest description it is a way of monitoring the pressure within the combustion chamber in realtime.
Why the hell do we need that?
if you are asking that then you are on the wrong forum! but i'll humour you anyway :p. Detonation is lethal for an internal combustion engine it blows head gaskets to shreds, it can burn holes straight through pistons, holes in the block bend conrods and wreak all sorts of havoc of your engine. it is much more serious in forced induction engines as the "charge" in the cylinder is much more volatile. in NA engines detonation is much less common but it does happen on a lesser scale in the form of pinking/pinging or knock this is still serious and most engines won't put up with much of it before blowing a head gasket, or worse!
So in answer to the question, it would be really handy when tuning your engine and trying to get the last couple of foot pounds out of it to be able to spot trouble before it happens and correct the tune accordingly.
The theory?
The gap between the spark plug is biased to a few hundred volts DC, the current flowing across the gap through the mixture in the combustion chamber is measured. as the pressure increases the current flow increases and is measured by a sensitive front end.
A sharp spike in the pressure after the initial ignition of the mixture indicates an abnormal burn and is likely a knock event occurring. the job of analyzing the waveform is probably too complex to do with discrete logic and op amps. it is very likely that any successful project would require a dedicated micro controller with the ability to take in to account RPM, load, atmospheric humidity and Manifold Air Temp in fact most of the factors required by the XDP in FreeEMS possibly including including timing information.
So come on guys lets get some ideas on e-paper and get some cutting edge feedback signals back to the FreeEMS of the future.
