This slows down the explosion, as the gasses have to escape from through the narrow passage into the cylinder。 This gives a softer bang and a smoother engine, but the gasses have to work harder, which lowers the efficiency a little。 However the newer breed of DI engines use other techniques to tame the behavior of the engine, such as two stage injection, electronic control

The injector on a diesel engine is its most complex component and has been the subject of a great deal of development and innovation。 On any specific engine it may be located in a variety of places。 The injector has to be able to withstand the temperature and pressure inside the cylinder and still deliver the fuel in a fine mist。 Getting the mist circulated in the cylinder

  so that it is evenly distributed is also a problem, so some diesel engines employ special induction valves, pre-combustion chambers or other devices to swirl the air in the combustion chamber or otherwise improve the ignition and combustion process。

  One major difference between a gas engine and a diesel engine is in the injection process。 Most car engines use port injection or a carburetor rather than direct injection。 In a car engine all of the fuel is loaded into the cylinder during the intake stroke and then compressed。 The compression of the fuel/air mixture limits the compression ratio of the engine。 If it compresses the air too much, the fuel/air mixture spontaneously ignites and causes knocking。

  A diesel compresses only air, so the compression ratio can be much higher。 The higher the compression ratio, the more power is generated。

  In the United States and Canada, diesel engines are most commonly found in trucks and buses。 In Europe, where fuel prices fluctuate around $3。00 to $4。00 per gallon, the fuel efficiency of the diesel has made it a popular choice for cars, and most European-market cars are available with a diesel or a turbo-diesel engine。

  Compared to gasoline-powered vehicles, diesels are more fuel efficient。 Diesel engines produce more torque, and they tend to be more durable。 They don't need an electric ignition system, which reduces their complexity。 However, they also create more noise, they can be difficult to start in extremely cold weather and they sometimes require more frequent routine maintenance than gasoline engines。

  Most passenger car diesel engines have a glow plug of some type。 When a diesel engine is cold, the air compression may not raise the air to a high enough temperature to ignite the fuel。 The glow plug is an electric heater that glows red-hot and helps to ignite the fuel when the engine is cold so that the engine can start。

  The amount of power which an engine can produce is limited by how much fuel it can burn, and the amount of fuel it can burn is limited by the amount of oxygen in the cylinder。 The amount of oxygen in the cylinder is limited by the amount of air in the cylinder。 So, if more power is wanted then more air is needed, how do we achieve this? Well a large engine has more air, so it can produce more power, or we can compress the air before it gets to the cylinders。This is what a super-charger does; it is a simple air compressor。 A super-charger is a mechanically driven compressor run by a belt off the crankshaft。

  A diesel engine has no spark plugs。 Because the air is so compressed and hot at the top of the stroke, the fuel ignites right away when it is injected。 This is why a diesel engine is called a "Compression Ignition" engine and gasoline engines are called "Spark Ignition" engine。 This also means that there are no ignition breakers, ignition coils, distributors and ignition wires to go bad。 This allows diesel engines to start no matter if it is dry or rainy and wet。论文网

  The key to fuel efficiency is to squeeze as much energy as possible out of a given amount of fuel by burning it as completely as possible。 Diesel fuel itself has the potential to produce more power than a like quantity of gasoline。 Furthermore, high compression ratios help diesels to burn their fuel more completely than gasoline engines。 And because diesels always intake a full charge of air while varying the amount of fuel, the air-fuel mixture tends to be a very lean mixture at lower power outputs, which helps burn the fuel more completely。 改善重型SCR系统的应用程序英文文献和中文翻译(6):http://www.youerw.com/fanyi/lunwen_97925.html