An internal combustion engine is one where an air-fuel mixture is burned inside a chamber. By this, chemical energy is converted into the mechanical energy which enables the vehicle to to run. The Internal combustion engines vary depending on the fuel used, for instance, diesel and petrol run engines. One of the most important aspects is the fuel supply system.
Gasoline engines are also known as spark ignition, Otto cycle, or petrol engines. The fuel system in these vehicles supplies the air and fuel to produce power to move the vehicle. In this article, we discuss briefly gasoline/petrol engine fuel delivery system components.
The fuel system components in spark ignition engine includes the air filters, fuel supply (tanks) and the carburetor.
Air filters remove the dust and debris particles entering the engine cylinder. If the air filters are not good they cannot filter, which results in improper fuel burning which reduces engine performances. Some of the types of air filters used include filter paper, oil bath and oil form.
Fuel is supplied from the tank to the engine through the fuel lines. The fuel in the fuel tank is supplied to the carburetor or fuel injector to produce combustion in the engine. Some of the fuel supply systems used in vehicles today are as follows.
Gravity feed system
As the name suggests the fuel flows to the engine by the action of gravitational force. To facilitate this, the fuel tank is located higher than the carburetor. The fuel is supplied to the carburetor through fuel lines.
In gravity feed type fuel supply system no fuel pumps are used. A fuel valve is placed between the fuel tank and the carburetor to turn on/off the fuel. This system is mostly used in two-wheeled automobiles. The carburetor is placed under the fuel tank.
Pressure or pump feed system
in this kind of fuel systems, pressure feed pumps are used in the vehicles. The fuel tank is kept away from the engine. The fuel pump is attached to the fuel tank and the engine. With the help of the fuel pump, the fuel is supplied to the engine. These are mostly used in modern vehicles and are replacing the gravity feed fuel system.
Vacuum feed system
In this system, the fuel tank is placed underneath the carburetor. When the piston moves downwards during suction stroke, a vacuum is created by which the fuel comes into the carburetor from the fuel lines.
Carburetor is a device that mixes the fuel and air in right proportion and supplies the air-fuel mixture to the combustion chamber. It also regulates the ratio of mixture. Normally the idea air-fuel ratio in spark ignition engine is 14: 1.
How the carburetor works
The carburetor consists of a fuel jet, venture, float chamber, needle valve, choke flap and throttle flap.
Air enters the carburetor when the piston moves downwards during suction stroke. In suction stroke, vacuum is created in the carburetor due to pressure difference air gets sucked into the carburetor.
The fuel jet is located in a narrow passage called venture. Here due to the pressure difference, the fuel gets mixed with air forming an air-fuel mixture. The mixture is then supplied to the combustion chambers.
The float chamber controls the flow of fuel to the carburetor. The needle valve is used to control the flow of fuel from the fuel pump to the float chamber. The choke flap controls the flow of air into the carburetor. The throttle valve is in the form of a flat circular metal disc mounted on the spindle used to control the flow if air-fuel mixture into the combustion chamber.
Modern automobiles are equipped with fuel systems helps vehicles owners save and create the minimal impact on the environment.