Diesel Engines Mechanical SSSP | Fuel Systems SSSP | HP-Fuel Systems SSSP | Fuel Injection Rate Control Flashcards
In modern fuel injection systems, what is meant by the injection rate? How does it differ from “fuel rate”?
Injection Rate = quantity of fuel injected per degree of crank angle rotation.
DIFFERS from “fuel rate” (an expression of fuel consumption) as described:
Fuel Rate = quantity of fuel burned per hour.
what is the most significant advancement of contemporary injection technology and why?
Injection Rate Control, because it affects fuel consumption, exhaust emissions performance, and combustion noise.
when the ECM accounts for changes in fuel density due to temperature changes, what is injection rate reported as? How does this differ from how injection rate is generically reported?
milligrams per stroke.
DIFFERS from how injection rate is generically
reported:
milliseconds or degrees of crankshaft rotation (compared with the delivery volume of the injection event).
what does rate-shaped injection refer to?
the shape of the injection discharge curve profile that is enabled through multiple injection events during a single combustion cycle; varies with varying injection pressures + the number of injection events within a given combustion cycle.
How many separate injection events can manufacturers of common rail systems currently provide during one combustion cycle, & what can the final event have to do with after-treatment regeneration?
As many as 7.
These events can include a post-combustion injection event that is used to dose the DPF or lean NOx trap (LNT, aka NOx adsorber catalyst - NAC) for regeneration.
What is pilot injection and what is another phrase for it?
Aka split-shot injection, it is
How many single pilot injection events do the most recent injection systems use, and why?
Research proves that an injection after the main combustion event (i.e., post-combustion injections) reduce the production of what?
Soot inside the cylinder.
The number and pressure of injection events vary with what 2 basic engine operating parameters? Explain.
Speed & Load.
At lower speeds…
