|
Multijet is Fiat Group's term for its current common rail direct injection turbodiesel engine range. Most of the Fiat, Alfa Romeo, Lancia range as well as certain Chrysler, RAM Trucks, Jeep and Maserati vehicles have Multijet engines. Ownership of some Fiat Multijet designs is shared with General Motors as part of a settlement of the failed merger between the two auto conglomerates. GM Powertrain Torino group in Turin, Italy manages their interest in these engines. Some PSA Peugeot Citroën diesel engines are also rebadged JTD units. The first-generation of Fiat's common rail diesel engine was known as JTD, an initialism of uniJet Turbo Diesel. == Characteristics == The property that distinguishes the Multijet from previous generations of common rail diesel engines from FCA is the combustion of the fuel, which is split into multiple injections, thus allowing for a more complete, quieter combustion in the cylinder. Compared to the first-generation JTD engines which only featured a smaller pilot and a larger main injection, Multijet is capable of up to five injections per combustion cycle which enables better, more efficient cold running, better performance especially in the lower rev-range, quieter operation as well as even lower consumptions and emissions. The time between injections has been reduced to 150 microseconds while the minimal injection quantity has been reduced from two to less than one milliliter. This enables even mid-sized sedans like the Alfa Romeo 156 and Lancia Lybra to achieve mileage upwards of 45 mpgUS (55 mpgimp or 5L/100 km) on country roads and highways. A sophisticated electronic control unit controls the injection and changes the injection logic and number of injections based on a multitude of parameters, most importantly revolutions per minute of the engine, engine torque requested by the driver and the temperature of the coolant. The injection pressure of the diesel fuel are limited between 1.400 bar (20.000 psi) on the 1.3 Multijet and 1.600 bar (23.000 psi) on the 2.4 Multijet 20V. In 2009 Fiat Powertrain introduced the third generation of this technology, called Multijet II. With its new and innovative injectors with hydraulically balanced solenoid valve and even higher injection pressure of 2.000 bar (29.000 psi) it is capable of even more precise controlling of the injected diesel fuel, injecting it in a quicker and more flexible manner. It enables up to eight consecutive injections per combustion cycle and implemented Injection Rate Shaping technology, which provides two very close pilot injection making the fuel delivery more continuous and modulated. This results in an engine that is quiet and has a smoother operation, lower emissions, better gas mileage and higher performance compared to the previous generation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「JTD engine」の詳細全文を読む スポンサード リンク
|