Different types of injection system in CI engines

A fuel injection system is also known as a fuel supply system in compression ignition (CI) engines. The fuel supply system of a diesel engine can be referred to as the engine’s heart, as its proper operation determines the engine’s performance. This system must feed, meter, inject, and atomize the fuel.

Fuel injection systems are more expensive since they are made with greater precision. Fuel will flow either by gravity or by a fuel feed pump, which will give fuel to the injection pump via the filter. This pump delivers fuel to the injectors located in the cylinder heads. Today you’ll learn the various types of fuel injection systems in compression ignition (CI) engines.


Types of fuel injection systems for diesel engine

Fuel injection systems in CI engines are classified into two; air injection and solid injection systems.


Air injection system:

To lower HC and CO emissions, an air injection system pumps fresh air into the engine’s exhaust ports. Unburned and partially burned fuel can be found in the exhaust fumes of an engine. This fuel continues to burn due to oxygen from the air injection system. The air pump, diverter valve, air distribution manifold, and air check valve are the main components of the system.

air injection system

Solid injection system:

A fuel injection system for a diesel engine in which a pump drives fuel into the combustion chamber via a fuel line and an atomizing nozzle. It is the injection of atomized fuel oil into a diesel engine’s combustion chamber under the pressure of the liquid fuel. The airless mechanical injection system is another name for the solid injection system.

solid injection system

Without the need for compressed air, liquid fuel is fed straight into the combustion chamber with this technique. As a result, it’s known as an airless mechanical injection system. The solid injection system is classified into three types:

Individual pump system – in these types of fuel injection, fuel will flow from the storage tank through the filters and then to the low-pressure pumps, as indicated. The fuel is pumped from this low-pressure pump to four independent metering and pressure pumps. Individual injectors are installed in the cylinder heads, and these independent metering and pressure pumps will pump the fuel to them. These are found in big, slow-moving engines.

Distributor system – Fuel will flow from the storage tank through filters to the low-pressure pump, then to the metering and pressure pumps. This metering and pressure pump provides fuel to a distributor unit, which distributes and sends the correct amount of gasoline to each injector/cylinder. Small and medium-sized engines use this part.

Common rail system – in these types of fuel injection systems, fuel passes via filters from the storage tank to the low-pressure pump in this scenario. The fuel is pumped from the low-pressure pump to the high-pressure pump, which then pumps the fuel to the high-pressure pump, which then pumps the fuel to the common rail. As a result, high-pressure fuel is collected in a common rail, and the needed amount of gasoline is delivered to injectors/cylinders via metering devices. This mechanism is commonly found in Cummins and multi-cylinder engines.

Electronic Fuel Injection (EFI) System:

In 1965, electronic technology was first used in autos. Electronic components account for 30–40% of vehicle costs. In autos, electronics and computers are used to achieve maximum power and efficiency. EFI systems used a variety of sensors to detect temperature, gas pressure, throttle valve position, and airflow rate, among other things. The data is fed to the Electronic Control Unit (ECU), which is essentially a computer, using sensors. This ECU analyzes data and controls injectors and other devices to achieve maximum power, efficiency, and emissions.

Multiport Fuel injection System (MPFI):

At all engine speeds and loads, a Multipoint Fuel Injection system is utilized to give an air-fuel mixture of the right strength and quantity to each cylinder of a multi-cylinder engine. The multiport fuel injection system work under two basic arrangement:

Port injection – In this example, the injector is located near the inlet valve in the intake manifold. The injector squirts gasoline into the air that passes via the intake manifold. The cylinder is filled with a homogeneous air-fuel combination. It’s worth noting that each cylinder has its own injector in the intake manifold. Port injection offers uniform fuel distribution, an increase in power output, and more precise control of the air-fuel ratio.

Throttle body injection – The injector is located at a single place in the throttle body in this scenario. The amount of air that enters the intake manifold is controlled by the throttle valve.

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That is all for this article, where the various types of fuel injection systems in compression ignition (CI) engines are been discussed. I hope you learn a lot from the reading, if so, kindly share with other students. Thanks for reading, see you around!