The diesel motor pump is the main component of the injection system of a diesel vehicle since it is very precise and is responsible for increasing the fuel pressure so that the injectors always receive the necessary amount of fuel at the right time.
Its main function is to increase the fuel pressure, adjust it to the operating speed of the injectors; Measure the amount of fuel injected into the cylinder and adjust the maximum and minimum engine revolutions.
The amount of fuel injected in each engine work cycle depends on its properties, operating conditions, high internal pressure in the chamber and the need to achieve a good air-fuel mixture for complete combustion.
The purpose of the diesel engine pump system is achieved by the work done by the entire system, from the fuel tank to the injectors.
The diesel motor pump is synchronized with the movement of the engine through a flexible coupling and is a piston pump responsible for providing a variable flow rate to the injectors that circulate through the pistons of each cylinder.
Functions of each type of diesel motor pump
There are two types of fuel injection pumps in diesel engines today, linear and rotary. Linear pumps are typically used in high compression ratio engines. Rotary pumps are normally used in medium compression ratio engines and of course both are very robust as they must withstand the pressure of the injection system.
Since a diesel engine attempts to burn at a constant pressure, the amount of fuel injected must be distributed over the entire injection time so that a certain amount of fuel can be burned in that time.
The linear diesel engine pump, invented by Robert Bosch in the early 20th century, uses a mechanical speed controller to distribute the injection flow and a hydraulic controller to change the injection direction.
When the camshaft begins to rotate, the impeller and the piston located in the pump cylinder begin to move, at the same time the accelerator is pressed, the rack is activated by turning the screw and more fuel is supplied to the cylinder of the pump. bomb.
The operation of the diesel linear injection pump is like the piston liner assembly in a conventional engine since, as we mentioned before, it is possible to synchronize the injection pump with the engine for its operation due to the connection of the camshaft to the engine.
What is an injection system?
The injection system is responsible for controlling the flow of fuel into and out of the engine. It consists of a low pressure stage and a high pressure stage, the latter located where the pump is located, which creates the pressure necessary to supply fuel to the engine and the high pressure circuit.
The pump is also fed by this low pressure circuit and supervises the supply of fuel from the tank and is also capable of filtering it so that it enters the high pressure circuit, completely or almost free of impurities and moisture.
The system may vary depending on the type of injection system and the characteristics of the pump integrated with the high pressure pump.
It is interesting that the operation of the injection pump is similar to the piston-liner assembly of a common engine, and thanks to the connection of the camshaft with the engine, it is possible to synchronize the injection pump with respect to its operation, and thanks to Technological advances have allowed us to develop current and modern systems such as TDI, HDI Common Rail and the Injector-Pump system.
Turbocharged direct injection (TDI) system
A direct injection system in which fuel is injected directly into the top of the piston to improve engine performance. Therefore, the higher the pressure at which the fuel is injected, the finer the atomization will be in the engine’s combustion chamber, creating a more intense fuel mixture that also contains air particles.
Furthermore, the higher the intensity of the process, the higher the combustion efficiency. It provides high performance and, more importantly, high fuel energy consumption, contributing to the possible reduction of CO2 emissions.
The injectors involved in the process are part of the diesel fuel injection system and are activated by the pressure of the pump, which is mechanical, during each injection cycle.
HDI (High Pressure Direct Injection) Common Rail System
This system provides higher performance and lower fuel consumption because it is a common channel injection system consisting of a multipoint direct injection system used only in diesel engines.
Accumulator injection systems are considered more flexible than rotary systems because they adapt better to the operation of the engine, since injection and pressure are generated in different directions.
The injectors in this system are activated by electrical pulses sent by the control unit, so the injectors must be electromechanical to produce more injection per cycle, and reduce polluting emissions and noise reduction, and this is the important role of the elements that are part of the HDI system.
This is a system that combines pressurization with fuel injection in the same combustion chamber; Unlike a common rail, where the pressure is in the pipes, the injectors only decide how and when to stop giving fuel, so each cylinder has its own injection pump.
The drive system is mechanical and receives the necessary pressure from the camshaft, which is responsible for opening and closing the valves.
The system consists of a low pressure fuel supply and a high pressure fuel supply, both with appropriate control electronics consisting of sensors and actuators. They inject the right amount at the right time with the perfect pressure.
The advantage of this system is that the higher the injection pressure, the lower the emission of pollutants.
Diesel Engine Pump Functions
The diesel engine injection pump system aims to inject fuel at high pressure into the combustion chambers of the various cylinders of the engine.
The diesel fuel pump system application performs the following functions:
- Supply the engine with the necessary fuel under all conditions.
- Precise fuel injection into each cylinder in the correct and specified order.
- Creates high injection and distribution pressure in the cylinders.
- Independence of the motor rotation speed.
Thanks to these applications, there is smoother operation, almost 50% more at low revolutions, 25% more power and 20% less fuel consumption, which allows compliance with current and future environmental regulations on emissions. admissible of these hydrocarbon particles.
Main Causes of Failure or Wear of the Diesel Motor Pump
In general, the most common component failures between the diesel pump and the injectors are due to clogging of the fuel filters or the injectors themselves, or the presence of air in the fuel lines.
These jams are caused by the accumulation of dirt and/or deposits and can be completely avoided with good vehicle maintenance.
Air in the lines is often due to an ignition problem, which can usually be fixed by bleeding the system.
Among the main causes of problems related to injection pumps, we find the following hypotheses:
- Wear of mechanical parts.
- The constant friction to which the pumps are subjected causes their usefulness to begin to decrease as their components deteriorate.
- The diesel fuel filter is bad.
- If this mechanical element cannot perform its function, it can create undesirable elements in the syringe pump, often leading to clogging and contamination of the system.
- Poor quality fuel.
- Low priced fuel means contamination in the diesel or gasoline chain, often leading to more impurities and pump and engine failure.
Facilitating lubrication and preventing dirt are two important prerequisites
Sometimes we look for the cause of the failure of the diesel motor pump or gasoline injection pump among complex problems. But in many cases it is due to simple processes and, most importantly, the lack of adequate preventive maintenance. If you notice any of the following symptoms, it is time to take it to a trusted mechanic:
- Excessive fuel consumption.
- White or black smoke comes out of the exhaust pipe.
- The engine stops suddenly.
- Pull while driving.
- The engine is difficult to stop.
- The vehicle accelerates or stops on its own.