Previous Year Question
In which of the following types of heat engines carburetor is used?
Diesel engine
Steam engine
Petrol engine
Both diesel and petrol engines
Correct Answer: C
Detailed Solution
A Carburetor is traditionally used in a Petrol/Spark-Ignition Engine. Its main function is to mix Petrol and Air in the appropriate proportion to prepare a combustible air-fuel mixture for the engine cylinder.
A Carburetor helps atomize and vaporize liquid petrol in the air stream. According to Bharat Skills automotive training material, a Carburetor receives petrol from the fuel pump, mixes it with air in the proper proportion and sends the mixture towards the cylinder during the intake stroke.
Its three important functions can be understood as Mixing, Vaporization and Atomization. Since the required air-fuel mixture changes with engine speed and load, the Carburetor must supply a suitable mixture under different operating conditions.
A Diesel Engine does not use a Carburetor. A Diesel engine is a Compression-Ignition (CI) engine. During the intake stroke, primarily air enters the cylinder, it is highly compressed, and Diesel fuel is then injected at high pressure. Bharat Skills training material also identifies the fuel-injection system as the principal system used in CI engines.
A Steam Engine is an external-combustion engine. An air-petrol mixture is not ignited by a spark inside its cylinder; therefore, it does not require a Carburetor.
Current Technology Note
Most modern Petrol cars today also use Electronic Fuel Injection (EFI/MPFI/GDI) systems instead of traditional Carburetors because these provide more precise fuel metering. However, in terms of engine principle and traditional classification, the Carburetor is associated with the Petrol/Spark-Ignition Engine.