Features of High Pressure Common Rail Electronic Injection
Posted: 2015-04-24 04:16:08 Hits: 1533
High pressure common rail electronic injection refers to the closed-loop system which is made up of high pressure oil pimp, pressure sensor and ECU, separating production of injection pressure from injection completely. High pressure oil pump transmits high pressure fuel to common rail, realizing precision control through oil pressure inside common rail. Pressure inside high pressure rail has no relationship with revolving speed of engine, which can significantly reduce extents that supply pressure of diesel engine changes with revolving speed of engine.
High pressure common rail utilizes common rail cavity having high volume to accumulate high pressure fuel transmitted by oil pump, eliminating pressure fluctuation of fuel, and then transmitting to every fuel injector. The system controls starting and ending of injection through solenoid valve on injector. High pressure common rail electronic injection has following features.
High pressure inside common rail cavity is directly used for injection, which can leave out pressurization mechanism inside injector. Moreover, high pressure exits inside common rail cavity constantly. So torque of driving force required by high pressure oil pump is much lower, compared of that on conventional oil pump.
Through pressure regulation solenoid valve on high pressure oil pump, high pressure common rail can regulate flexibly oil pressure based on situations of engine load and requirements of economy or emission performance, especially optimizing low speed performance of engine.
Common rail can control injection timing, injection oil mass and injection rate through solenoid valve. It also can regulate flexibly injection oil mass of pilot injection and post injection under different conditions and the distance between pilot injection and main injection.
Pilot injection is before main injection. A small part of fuel in injected into cylinder, premixed inside cylinder or burned partly, reducing ignition lag phase of main injection. So, rising rate of pressure inside cylinder and peak pressure descend. Engine works mildly. Meanwhile, temperature inside cylinder reducing also decreases emissions of NOX. Pilot injection also can lower possibility of fire and improving cold starting system of high pressure common rail.
