[help needed] Electronic diesel control 101?

[AndreyB]

Subj. Looking for "diesel control for dummies"
I know there are multiple generations - the older stuff on one side is easier and the common rail on the other side is challenging. This is pretty much all I know about diesel engine control.

[kb1gtt]

The new stuff is very similar to port injection, however it fires during combustion. Some can fire 4 to 5 times during combustion to control the flame front speed AKA ping/knock prevention. The new stuff generally requires higher voltages, like 80V to 300V ish.

[AndreyB]

Oh, so before we even start talking about the logic, we would need to talk about the hardware?

[kb1gtt]

Correct, there are may versions of hardware. So you really need a good base understanding to get a feel for the software requirements.

Back in the 80's the VW diesel was very common, it was pure mechanical, only electricity was to turn on a valve that allowed fuel to flow. I seem to recall there was some kind of level attached to the long pedal, and another that was a kind of choke equiv. The next big place for electricity was the glow plugs. They would need to run for a while to warm up before you tried to start. You could get fast plugs which would fail more commonly, or you could get the slow plugs which were more robust, but needed more time to warm up.

I seem to recall other setups on trucks had a solenoid that adjust the advance, such that electronics could enhance the emissions or power or something like that. I think it was basically PWM to increase or decrease the timing. So it was still very mechanical.

Eventually emissions demanded more control over the particulates, and NO emissions, which required better control over the flame front speed, and the burn time. Flame fronts that move to fast are two hot and the nitrogen starts to burn which makes to much nitrogen emissions. As well large trucks found significantly less fuel was required for the same power with a better tuned engine. This forced many OEM's into electronic controls, such that failed emissions could turn on a check light, and you could get better fuel economy. This was perhaps in the early 90's that we started to see common rail injection become popular. This is very similar to the injection we do today, with pulsed injectors and a common pressurized fuel rail.

I have some simulations for a high voltage driver some where. I'll see if can find them and post them here.