car engine nozzle DSLA145P366/0 433 175 061 common rail nozzle

car engine nozzle DSLA145P366/0 433 175 061 common rail nozzle
Diesel engines have historically used various forms of fuel injection. Two common types include the unit injection system and the distributor/inline pump systems. While these older systems provide accurate fuel quantity and injection timing control, they are limited by several factors:
They are cam driven, and injection pressure is proportional to engine speed. This typically means that the highest injection pressure can only be achieved at the highest engine speed and the maximum achievable injection pressure decreases as engine speed decreases. This relationship is true with all pumps, even those used on common rail systems. With unit or distributor systems, the injection pressure is tied to the instantaneous pressure of a single pumping event with no accumulator, and thus the relationship is more prominent and troublesome.
They are limited in the number and timing of injection events that can be commanded during a single combustion event. While multiple injection events are possible with these older systems, it is much more difficult and costly to achieve.
For the typical distributor/inline system, the start of injection occurs at a pre-determined pressure (often referred to as: pop pressure) and ends at a pre-determined pressure. This characteristic results from "dumb" injectors in the cylinder head which open and close at pressures determined by the spring preload applied to the plunger in the injector. Once the pressure in the injector reaches a pre-determined level, the plunger lifts and injection starts.