CommonRail - High pressure electronic diesel injection
- Aftermarket controllers:
- Technical papers:
http://www.vehicular.isy.liu.se/Publications/MSc/00_EX_3081_KA.pdf
Paper on the effect of timing and duration of main and pilot injection. Mainly conserning noise levels.
http://www.macchine.unisa.it/meca01/papers/MECA01_paper06.pdf
Modelling of a diesel engine common rail injection system
http://www.nt.ntnu.no/users/skoge/prost/proceedings/ifac2005/Fullpapers/04315.pdf
Achieving lower exhaust emissions and better performance in an HSDI diesel engine with multiple injections
http://www.tytlabs.co.jp/office/elibrary/ereview/rev373epdf/e373_009hotta.pdf
Optimizing the multiple injection settings for a HSDI diesel engine
- Issues:
AFAIK there is no general aftermarket common rail diesel ECU available. This makes it impossible to use a common rail diesel in applications where the stock ECU does not work. One popular application can be marinisation of car engines. Another might be putting modern diesels in older cars. Or for tractors or gensets or whatever...
One critical thing would be timing for injection
- Timing:
pilot injection
~ -40degrees (2-4mm^3) Timing not critical. Optimal timing is dependant on load and revs.
Main injection
no load -2 - 4
part load -6 - 4
full load -15 - -6
duration 40-60 deg crank
5000 crank rpm = 5000 / 60 rps = 5000/60 * 360 degps = 33us/deg
average unexpected delay = 7us = 7/33 deg = 0.21deg
- Requirements:
Glow plug output.
A small typical diesel like Volvo D5244T4-7 uses max 12V and 22A during a minute. Most engines has a separate relay for this. Some engines regulate the voltage (and hence current) over the glow plug. The purpose is to reach high temperatures fast with a high current, after which the current is lowered to maintain the temperature. On larger (more plugs) or older engines it might not be feasable to output the required current directly from the ECU. It might then be better to control a relay.
Rail pressure sensor input
Commonly outputs 0-5V. Needs +5V and an ADC
Rail pressure control valve output
PWM regulated electromagnetic valve with coil resistance of 2-3Ohms.
Unit injector
PWM regulated (pull and hold) up to 20A@80V for an typical electromagnetic injector. I don't have any data for piezolectric ones.
Commanded throttle position
0-5V or CAN
Manifold Air Pressure (MAP)
Manifold Air Temperature
Oil pressure
Coolant temperature
Crank shaft rotation sensor
Cam sensor
I/O for variable geometry turbo control
Other
I/O for swirl throttle, output to pull starter selenoid.