CRDI History
Posted: 2015-07-07 04:25:27 Hits: 4137
CRDI is short for common rail direct injection, meaning foe high pressure common rail diesel direct injection. CRDI, SDI and TD are diesel engine technologies developed by BOSCH. Common rail system consists of high pressure pump, spray bar, high pressure accumulator, injector, ECU, sensor and actuator.
BOSCH was the first company which began to batch manufacture passenger vehicles using CRDI in 1997. At that time, BOSCH released diesel Benz C-class using common rail system jointly with Mercedes-Benz. Alfa Romeo 156 was also one of the vehicles which used high pressure common rail system at the earliest. CRDI has been developed into the third generation.
High pressure pump on the first generation common rail system was always maintaining the highest pressure, resulting in fuel waste and quite high fuel temperature. The first common rail system was only designed for commercial vehicles. The highest injection pressure was 140MPa while the highest injection pressure on passenger vehicles was 135MPa.
The second generation common rail system could change delivery pressure according to requirements of engine, having both pilot injection and post injection. For oil pump controlling oil mass, injection pressure could reach to 160MPa. Even though the pressure was quite low, the system still could provide moderate injection pressure based on actual conditions. It was not only contribute to lowering fuels consumption, but also reducing fuels temperature, leaving out cooling device used to cool fuel. Pilot injection could reduce noises of engines. Before millionth seconds of main injection, few fuels were injected into cylinder for compression ignition, preheating combustor. Cylinder having been preheated made compression ignition after main injection easier. Pressure and temperature inside cylinder would not rise suddenly, in favor of reducing combustion noises. Post injection was conducted during expansion, causing the second burning. Temperature inside cylinder was increased by 200～250℃, reducing hydrocarbons in exhaust. The second generation common rail system provided by BOSCH had already been tested on Volvo S60 and V70D5, BMW 320d.
The third generation common rail system was equipped with piezo inline injector. In 2003, the third generation common rail system – piezo common rail system came out.
