Piezo Common Rail System Introduction

Diesel common rail system has been developed into the third generation, having strong technical potential. High pressure pump on the first generation common rail system is always maintaining high pressure, resulting in energy waste and high temperature. The second generation common rail system can change delivery pressure according to the requirements of engines, having both pilot injection and post injection. Pilot injection can reduce the noises of engine. Before millionth seconds of main injection, a small quantity of fuels is injected into cylinder for compression ignition, preheating combustor. Cylinder makes compression ignition after main injection more easily. The pressure and temperature inside cylinder will not rise suddenly any wore, which is advantageous for reducing combustion noises. Post injection is carried out during expansion, causing second combustion, which raises temperature inside cylinder from 200℃ to 250℃ and reduces hydrocarbons contained in exhaustion. 

 

Due to powerful technical potential, manufacturers have already paid attention to the third generation common rail system – piezo common rail system. Piezoelectric actuator instead magnet valve realizes more precise injection regulation. Without oil return tube, the structure is simpler. Pressure can be elastically regulated from 200MPa to 2000 MPa. The minimum injection duration can be controlled below 0.5mm³, reducing smoke intensity and NO_x emission.

 

Electronic control is that fuel injection system is controlled by ECU. ECU realizes precise control on quantity and moment of every injector so that economical efficiency and dynamic performance can reach to the best balance. However, conventional diesel engine is mechanical control. Control precision cannot be ensured.

 

High pressure means that the pressure of injection system is higher than conventional diesel engine by 3 times. The highest pressure can reach to 200MPa while injection pressure on conventional diesel engine ranges from 60MPa to 70MPa. The higher pressure is, the better atomization is and the more sufficient combustion is, highly improving dynamic performance and realizing fuel efficient further. 

 

Common rail is that common delivery pipe supplies oil to every injector at the same time. The injection quantity has been calculated precisely through ECU. Every injector is supplied with oil having the same quantity and pressure meanwhile. The engine operation is smooth, optimizing overall performance of diesel engine.