What Is a Diesel Fuel Pump? Definition, Meaning and Concept
Although diesel engines and gasoline engines are internal combustion engines, from there the similarity essentially ends. Both engines ignite a fuel/air mixture that releases an explosive force to drive a crankshaft, driving, for example, the wheels of a car. However, the method of fuel ignition is very different between the two engines, with the diesel fuel pump being crucial for this ignition.
Diesel fuel is heavier than gasoline, and not as volatile. Also, diesel fuel evaporates more slowly than gasoline. The popularity of diesel engines is largely a result of the energy density of diesel fuel, which is considerably higher than the density of gasoline, resulting in better energy efficiency. The diesel engine, unlike gasoline engines, does not use a spark to ignite the fuel/air mixture. The heat of the compressed air in the cylinder of the diesel engine provides the ignition source, thus eliminating the need for spark plugs.
Therefore, a diesel fuel pump, often called a diesel fuel injection pump, must inject fuel directly into the cylinder. Diesel fuel ignites when it comes into contact with the superheated, supercompressed air inside the cylinder. Sometimes diesel fuel injection is aided by compressed air injection as a boost to the fuel injection process.
The diesel fuel pump is quite a complex and sturdy mechanism. In fact, it is the most complex part of the diesel engine. Additionally, a diesel fuel pump must be durable enough to withstand the pressure of compressed air and the heat of the injection process. The diesel fuel pump must maintain the fine mist of fuel necessary for proper ignition under these extreme conditions.
Diesel fuel pumps can be located anywhere on the engine, depending on the manufacturer's design. Much experimentation has been done over the years regarding the most effective placement of the diesel fuel pump. So far it appears that as long as the pump is mounted to the engine it will indeed deliver fuel to the cylinders. A gasoline fuel pump, on the other hand, can be mounted anywhere in the engine compartment or along the fuel distribution system.
Depending on the location and design of the diesel fuel injection pump, precombustion chambers, custom induction valves, and other systems are often used in the injection process. These injection boosters often help circulate or spin the air inside the cylinder for more efficient combustion. As with any engine fuel injection system, diesel fuel pumps are constantly being improved to be more efficient and less expensive.