How does injection pump work on a diesel

By pressurising and injecting the fuel, the system forces it into air that has been compressed to high pressure in the combustion chamber.

Some types of fuel tanks also have a fuel sedimentor at the bottom of the filter to separate water content from the fuel. Pump elements such as the cylinder and plunger are built into the injection pump body. The fuel is compressed to high pressure when the cam lifts the plunger, and is then sent to the injector.

In diesel engines the intake of air is almost constant, irrespective of the rotating speed and load. If the injection quantity is changed with the engine speed and the injection timing is constant, the output and fuel consumption change.

Since the engine output is almost proportional to the injection quantity, this is adjusted by the accelerator pedal. The main purpose of the fuel injection system is to deliver fuel into the cylinders of an engine. In order for the engine to effectively make use of this fuel:. However, it is still not enough to deliver an accurately metered amount of fuel at the proper time to achieve good combustion. Additional aspects are critical to ensure proper fuel injection system performance including:.

The primary purposes of the diesel fuel injection system are graphically represented in Figure 1. Many specialized concepts and terms are used to describe the components and the operation of diesel fuel injection systems. Some of the more common of these include [] [] :. Nozzle holder or injector body refers to the part the nozzle is mounted on. In conventional injection systems this part mainly served the nozzle mounting and nozzle needle spring preloading function.

In common rail systems, it contains the main functional parts: the servo-hydraulic circuit and the hydraulic actuator electromagnetic or piezoelectric. Start of injection SOI or injection timing is the time at which injection of fuel into the combustion chamber begins. SOI is often indicated by an easily measured parameter such as the time that an electronic trigger is sent to the injector or a signal from a needle lift sensor that indicates when the injector needle valve starts to open.

The point in the cycle where this occurs is the indicated SOI. Due to the mechanical response of the injector, there can be a delay between the indicated SOI and the actual SOI when fuel exits the injector nozzle into the combustion chamber. Start of delivery. In some fuel systems, fuel injection is coordinated with the generation of high pressure.

In such systems, the start of delivery is the time when the high pressure pump starts to deliver fuel to the injector. The difference between start of delivery and SOI is affected by the length of time it takes for a pressure wave to travel between the pump and injector and is influenced by the length of line between the high pressure pump and the injector and by the speed of sound in the fuel.

The difference between the start of delivery and SOI can be referred to as injection delay. Injected fuel quantity is the amount of fuel delivered to an engine cylinder per power stroke. This pump is primarily used for medium to large trucks and construction machinery. A camshaft drives the fuel pressure and injection quantity control mechanisms within the pump body.

The elements in that body follow an injection order to feed fuel to each engine cylinder. Distributor injection pump. Also a mechanically controlled diesel fuel pump, the distributor injection pump has just one fuel pressure mechanism, despite the number of engine cylinders the vehicle may have.

The distributor is designed to follow the injection order to distribute pressurized fuel to each cylinder.