A typical system might have three stages of progressive filters--a filter screen at the tank or transfer pump, a primary fuel filter, and a secondary fuel filter. In series filters, all the fuel goes through one filter and then through the other. In parallel filters, part of the fuel goes through each filter.
For more information on fuel filters, see Diesel Fuel Filter Basics. Simple fuel systems use gravity or air pressure to get fuel from the tank to the injection pump. On modern high-speed diesel engines, a fuel transfer pump is normally used. This pump, driven by the engine, supplies fuel automatically to the diesel injection system.
The pump often has a hand primer lever for bleeding air from the system. Modern injection pumps are almost all jerk pumps that use the plunger and cam method of fuel injection. Individual pump and injector for each cylinder.
Combined pump and injector for each cylinder unit injector type. Learn about alternative fuel options. How Do Diesel Vehicles Work? Key Components of a Light-Duty Diesel Vehicle Aftertreatment system: This system is comprised of multiple components, which are responsible for filtering the engine exhaust gas to meet tailpipe emission requirements.
After the exhaust gas of the engine is filtered through the diesel particulate filter DPF and the diesel oxidation catalyst to reduce particulate matter, diesel exhaust fluid DEF is injected into the exhaust gas mixture, then reduced to nitrogen and water by chemical conversion within the selective catalytic reducer SCR before being released into the atmosphere via the vehicle's tailpipe. And of course, almost all heavy-duty construction, farm, and mining equipment is diesel powered.
World commerce effectively runs on diesel power. While similar in appearance, critical differences set diesel and gasoline engines apart from each other and dictate which type of engine is best suited for any specific application including trucks and autos.
Diesel engines and gasoline engines are both internal combustion IC engines. Fuel and air are combined and burned inside the engine to make power. Like a gasoline engine, a diesel engine has cylinders, a crankshaft, connecting rods, and pistons to transfer the energy of the fuel from a linear to rotary motion. Gasoline engine are spark ignition engines and diesel-fueled engines are compression ignition engines.
These cycles are essentially the same in both engine types except for the combustion cycle where the gasoline engine is spark initiated and the diesel is compression initiated.
The difference is central to the superiority of the diesel for applications requiring high efficiency and high torque functionality with good fuel economy. A gasoline fueled IC engine takes in premixed fuel and air via the induction system, compresses it in each cylinder with a piston and ignites the mixture with a spark plug. The ensuing combustion cycle expands the burning mixture and raises the cylinder pressure to push the piston down and generate torque.
In a diesel engine air and fuel are not pre-mixed. Air is inducted into the cylinders and compressed by the piston to a much higher pressure than in a gasoline engine; up to in some cases.
At this point fuel is injected into the hot compressed air causing it to ignite instantly. Higher cylinder pressure is generated, creating more torque to power the vehicle. Diesel engines deliver higher efficiency levels for several reasons. One good reason is because the higher cylinder pressure at the time of fuel injection creates a much denser mixture that packs a stronger punch; mixture density being paramount to power creation.
Higher compression also makes the fuel burn more completely, releasing more energy because diesel fuel yields a higher energy density. Diesel fuel also has a lubricity component that helps reduce friction in the cylinders. While the initiation of combustion differs from a typical gasoline engine, a fundamental difference also exists in the combustion chamber design to optimize fuel atomization. A diesel engine does not contain a spark plug. A gasoline engine compresses at a ratio of to , while a diesel engine compresses at a ratio of to as high as The higher compression ratio of the diesel engine leads to better efficiency.
Gasoline engines generally use either carburetion , in which the air and fuel are mixed long before the air enters the cylinder, or port fuel injection , in which the fuel is injected just prior to the intake stroke outside the cylinder. In a gasoline engine, therefore, all of the fuel is loaded into the cylinder during the intake stroke and then compressed. Diesel engines use direct fuel injection i. A diesel engine compresses only air, so the compression ratio can be much higher.
The higher the compression ratio, the more power generated.
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