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Wi | In laymens terms yes, common rail injectors are typically fired by a powerful electromagnet. Newer systems use Piezo crystals though instead as they are faster however they take a lot of juice to operate. For example the Piezo injector in the LML Duramax takes up to 275 volts to open, however once open it only takes 12 to maintain it whereas older injectors like the LLY used around 50v constant. This is why you see orange wiring loom in the new Duramaxs.
The term common rail comes from the fact the injectors are all liked into a common high pressure rail fed by a common rail pump. The CP3 was the pump of choice until lately. The CP3 has 3 cavities that pressurize fuel as it rotates, sort of like a wankel engine. Many engines switched to the CP4 for the tighter emissions, it operates at higher pressures and can be timed to deliver fuel to the rail as injectors are firing. It operates more like a piston pump. These pumps have proven to be much less reliable than the CP3 though.
Most common rail systems operate from 20,000psi-35,000psi whereas an old mechanical pump tractor will maybe see 5000psi. Thats idle pressure for many common rail engines.
The injector you are describing on a detroit is referred to as a unit injector due to it being operated by the cam.
There is also the HUEI which is a hydraulic unit injector where low pressure fuel is kept at the injectors and the injector is fired by high pressure engine oil. Cat and the older Powerstrokes used this. | |
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Explain common rail to me in small words
