It is amazing how many similar interests there are in the industrial community. I have a functional Bridgeport VMC in the garage and a Makino wire EDM that needs a little maintenance before it is fired up. I'm not really interested in something unless I think I can build something myself.
In the driveway is an '85 Chevy 6.2L diesel flatbed. I have about $1200 in it right now. The diesel technology from '85 is much different than today. It runs fine but does not have forced air induction and belches black smoke. Back then they didn't care much about air-fuel ratios with diesels. I did quite a bit of research on diesels mostly in the racing arena (torque = speed). Bosch does have 32,000PSI injectors but they can be fed with a relatively low pressure pump of 1500PSI. The fuel is compressed in the injector using a piezo stack. Control of the piezo stack is the key. There is probably a science behind controlling the new direct injection (DI) systems. Some mfgs are known to pressurize the cylinder and inject a minimal drop of fuel in a small auxiliary pocket of the combustion chamber. As the fuel ignites and starts to spread the flame front into the main chamber a second and longer pulse of fuel is injected and probably at top dead center or after (power pulse). The result is a much quieter explosion by controlling the volume of fuel over time. A standard volume of fuel in a power stroke thrown in all at once yields a bang (old style knock). A small puff of an explosion accompanied by a longer pulse width softens the blow but the expansion of gases still provides a lot of torque. The small volume of fuel from DI is also compatible with propane injection because the propane is looking for any ignition source, large or small. This would also help fuel economy. I wouldn't be opposed to putting a 10 gal propane tank in the trunk. I like diesel because it is simple. Put a drop of oil in an environment with a high compression ratio at 150 degrees F and boom. The newer Bosch direct injection (DI) injectors can output as little as 1 mm^3 of diesel by sending a narrow pulse width to the injector. You can virtually figure your fuel economy based on some assumptions: 1 mm^3 fuel every other revolution per cylinder in a 4-cycle engine, 1 mm^3 of fuel per cylinder is enough to provide sufficient torque to overcome wind and rolling resistance (40HP typ), diesel produces 2x the torque per firing than gas and a light weight chassis typically running at 60MPH highway speed. Instead of using a rotary encoder on the crank I would use a 4-6-8 position sensor that had fairly accurate geometry cylinder to cylinder and key off that. The engine is not going to change speed so quickly that you can't predict where it is. From one cylinder firing to the next firing the engine won't double in speed. Diesels accelerate slowly. I would have predictive software that knew the current speed and acceleration of the crank. A combination of this data and the position sensor would tell me when to fire. As long as I am consistent in timing cylinder to cylinder the engine won't care. The DI injectors allow you to tweak before, during and after top dead center fuel pulses. Diesel is a slow burning fuel. At higher speeds you would need to advance the DI pulse to achieve a near complete burn by the end of the cycle. At 5000 RPM the combustion period is about 6ms. I'll probably never get to build my 2L 4-cyl 5000RPM 300HP diesel racing engine but some day may buy a DI injector for $300 or so and retrofit my 21" JD lawnmower with a diesel. Dennis ----- Original Message ----- From: "Stuart Stevenson" <[EMAIL PROTECTED]> To: "EMC2-Users-List" <Emc-users@lists.sourceforge.net> Sent: Friday, November 30, 2007 11:51 AM Subject: Re: [Emc-users] diesel motor control > Gentlemen, > I am like the 5 year old boy with a hammer. 'Everything' looks > like a nail. I want to control the injectors with EMC. > The current diesel technology is common rail injection using HIGH > injection pressure. Bosch talks about 2200 bar. 2200 bar is almost > 32,000 psi. WOW! > They also have multiple injections per combustion cycle. > They also talk about variable geometry during the injection cycle. > This sounds like a job (nail) for EMC. > I won't try for the high pressures as I will use currently > available injectors and pumps. > To get the project going I need to start simple. > I will use a used pump and injectors from a Volkswagon (or other). > I will modify the head to accept the injectors. I will build an > adaptor or bracket to mount the pump. > Voila! :) running in two weeks! heh heh heh > thanks > Stuart > > ------------------------------------------------------------------------- > SF.Net email is sponsored by: The Future of Linux Business White Paper > from Novell. From the desktop to the data center, Linux is going > mainstream. Let it simplify your IT future. > http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
