CARBURETOR
Hello mechons, in this sparking day we are going to explain to you about what are Carburetors, parts of a simple carburetor, what are the types of carburetors, how the carburetors work also the advantages and disadvantages of carburetors with its applications.
What are Carburetors?
(carburetor)
The carburetor is a device that is used for mixing the air and fuel in the correct and proper ratio of air-fuel mixture for an internal combustion engine for combustion. In general for burning the fuel inside the combustion chamber of an engine cylinder in all conditions we need a rich air-fuel mixture, to get such a rich air-fuel mixture we are using a device called Carburetor.
The main purpose of the carburetor is to regulate the air-fuel mixture ratio and by regulating that, it controls the speed of the engine since the speed of the engine depends upon the amount of air-fuel mixture passing inside the engine cylinder. And also the main thing is that we are using the carburetors only in Petrol engines(SI engines) and not in diesel engines(CI engines). (Here SI stands for - Spark Ignition & CI stands for Compressed Ignition). Just read our post about the difference between Spark and compressed ignition engine for more clarification in differences between these ignition system. Do you know, Why carburetors are used in petrol engines, not in diesel engines?
The carburetors are used only in Petrol engines i.e. Spark ignition because of the difference in the mode of combustion between Petrol and diesel engines.
In the case of a diesel engine, the fuel is burned when the fuel is injected at high pressure to the hot compressed air in the cylinder. This hot compressed air reaches the engine cylinder with the help of a turbocharger or natural respiration. And with the help of the Fuel pump, the fuel reaches the combustion chamber. And hence both fuel and air enter the combustion chamber separately. Thus with the help of that hot compressed air, the combustion process takes place in a diesel engine.
But in the case of a petrol engine, the combustion will occur only when the air-fuel mixture gets ignited by the spark from spark plug which is present inside the engine cylinder. This flow of air-fuel mixture is regulated and monitored by the carburetors.
So in petrol engines, we are using the mixture of fuel and air for the combustion process than a direct injection of fuel into the combustion chamber.
Thus to get that air-fuel mixture we are using Carburetors in Spark ignition(SI) or Petrol engines.
Parts of a Carburetor:
Ok, let's talk about the parts of the carburetors
So now, what are the parts of a Carburetor?A simple carburetor is comprised of the following parts which are listed below:- Throttle Valve
- Choke Valve
- Mixing Chamber
- Metering system
- Idling system
- Float Chamber
- Idle and Transfer port
- Venturi
- Strainer
Throttle Valve:The throttle Valve is one of the most important parts of a Carburetor. It regulates the air-fuel mixture which is supplied to the engine cylinder. The throttle valve is opened when the driver throttled the accelerator.
Choke valve:A valve that controls the air-fuel mixture is called a Choke valve. The primary function of the Choke valve is controlling the amount of air that is present inside the mixing chamber. The valve is remains opened partly, in the case when we are in need of a rich air-fuel mixture we can operate the valve and this valve remains very close to the inlet of the air passage, so we are able to get rich air-fuel mixture when we use this valve. We use this valve more in the rainy season because in those times is the engine will not get enough air to get started, so by using this valve we get rich air-fuel mixture to start the engine.
Mixing Chamber:The mixing process of air and fuel takes place in this chamber and then supplied to the cylinder of the engine. Hence it is called a mixing chamber.
Metering system:The flow of fuel into the nozzle is controlled by the metering system. The metering system is responsible for forming the correct air-fuel mixture. It contains two important parts:1. Metering orifice2. Fuel discharge nozzleWhen the air gets passes through the venturi, it creates a low-pressure field in the throat. Due to the difference in pressure, the fuel is discharged. The amount of fuel entering is controlled by the metering orifice and discharge hole at the exit of the fuel discharge nozzle.
What is the function of the nozzle tip in a carburetor?
The difference of level between the upper end of the main nozzle and float chamber fuel level is called nozzle lip.The function of the nozzle tip is to reduce the overflow of fuel from the nozzle, the main nozzle end is usually kept at a higher level than the float chamber fuel level.
Idling system: The idling system contains a passage directly from the float chamber to the Venturi tube. It creates a rich air-fuel mixture during the process of idling or throttling the accelerator up to 15%.
Float Chamber:It acts as a storage tank of fuel for a continuous supply of fuel to the engine cylinder. It has a float valve that regulates the level of fuel in the float chamber. When the level of fuel decreases the float will move downwards so that the fuel supply valve opens and the flow of fuel takes place. If the fuel level increases, the float will move upwards and the fuel valves close so that the supply of fuel flow can be stopped.
Idle and Transfer port:There are other two ports or nozzles present along with the main nozzle in the venturi for the supply of fuel to the engine cylinder called Idle and transfer ports or nozzles.
Venturi:A hollow tube which helps to decrease the air pressure of the chamber for which the fuel comes out from the fuel pipe.
Strainer: A component that is used for filtering the fuel before it gets enters the float chamber is called Strainer. It posses fine filters that remove the dust and other unwanted materials from the fuel. If these dust are not removed then, these specks of dust will block the nozzle.
Working of a simple carburetor
The Float and valves system maintains a constant level of fuel in the float chamber. The float chamber remains open in the atmosphere. The fuel from the fuel tank is supplied to the float chamber by using the fuel pump. The strainer now filters the fuel and removes the dust and unwanted materials from the fuel. Then this fuel is supplied to the main nozzle. The suction of air from the atmosphere takes place. This air passes through the venturi and it reduces the area of cross-section at the throat of the venturi.
Now the fuel is passed from the float chamber to a discharge jet tube which is at the tip of the throat of the venturi. Because of this, the pressure at the main nozzle and the velocity of the airflow increases. Due to the difference in pressure at the nozzle and the float chamber causes the formation of a mixture of atmospheric air and the fuel occurs. This difference in pressure at the float chamber and venturi is known as carburetor depression.
If we open the throttle valve more airflow will occur at the venturi tube and a large quantity of air and fuel mixture is supplied to the engine so that the engine can produce more power and also possess high speed, when close the throttle valve these actions takes place in the reverse way i.e. The quantity of air-fuel mixture reduces at venturi tube, so the power and speed of the engine get reduced.
Types of carburetors
So, let's start with the types of carburetors
what are the types of carburetors?
Based on the flow directions of the air-fuel mixture, the carburetors are classified into three basic types as follows:
1. Updraft carburetors2. Horizontal or side-draft carburetors3. Downdraft carburetors
Updraft carburetor
If the air supply is from the bottom side of the mixing chamber then it is called an updraft carburetor. The name itself will explain the working of this type, in updraft carburetors the air enters from the bottom side of the carburetor and moves towards the upside against the gravitational force, the fuel enters from the float chamber. Due to the difference in pressure between these two, chambers the venturi will mix the fuel that comes out from the float chamber with the inlet air and make the air-fuel mixture. And then this air-fuel mixture is passed to the throttle valve which is directly connected to the accelerator, now this air-fuel mixture is passed to the engine cylinder where the combustion will occur when we rise the accelerator. The main disadvantage of this type is this type of carburetors has to lift the fuel droplets against gravitational force by air friction, and also the jet tube cross-section is small, because of these disadvantages these type of carburetors cannot supply the air-fuel mixture at high-speed.
Horizontal or side draft carburetor
If the air supply from the side of the carburetor then it is called horizontal draft or side draft carburetor. In horizontal or side-draft carburetors, the jet tube is placed in the horizontal direction. The air is coming in through one end of the carburetor and gets mixed with the fuel to form an air-fuel mixture. Then this air-fuel mixture is passed to the engine cylinder. Here also the throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. This resembles downdraft carburetor, when you rotate the downdraft carburetor in a horizontal direction then it is a horizontal draft or side draft carburetor. The advantage of this type is there is no airflow of resistance.
Downdraft carburetor
If the air is supply is from the upper side of the mixing chamber then it is called down-draft carburetor. In a downdraft carburetor, the air-fuel mixture enters the carburetor from the upside and moves towards the downside of the carburetor with the help of gravity. This type of carburetors is also works under the same principle due to the pressure differences between the two venturi the fuel comes out from the chamber mixed with the air. The air-fuel mixture is controlled by the choke valve. The throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. These type of carburetors allows the proper flow of air-fuel mixture to the engine cylinder. These carburetors help to operate engines at both high and low speed.
Which type of carburetors are widely used and why?
In most of the cases down-draft carburetors are generally used, because of the advantages as follows :
1. The flow of the air-fuel mixture is assisted by gravity, so the engine function is better at lower speeds under load.2. We are able to achieve higher Volumetric efficiency when we use this type of carburetors.
Functions of a carburetor
The functions of a carburetor are :
1. The primary function of carburetors to produce an air-fuel mixture for combustion. 2. The speed of the engine is controlled by carburetors.3. It maintains the ratio of air and fuel in the air-fuel mixture.4. Maintaining a certain amount of fuel in the float chamber at all times. 5. To supply the correct amount of air-fuel mixture at the correct strength under all conditions of load and speed of the engine.
Advantages of the carburetor
1. Carburetor parts are cheap when compared to fuel injectors.2. By using this, we can get more air-fuel mixture. 3. In the case of road tests, carburetors produce more power and precision.
Disadvantages of the carburetor
1. At low speed, the air-fuel mixture supplied by the carburetor is so weak and it will notignite properly.2. The carburetor working may be affected by changes in atmospheric pressure.3. Fuel consumption and air emissions are more when compared to fuel injectors. 4. Cost of maintenance is higher than the fuel injection system.
Applications of Carburetor
1. Used in Spark-Ignition Engine. 2. Used in controlling the speed of the vehicles. 3. Used to convert the main fuel(petrol) into fine droplets and it mixes the fuel with air for burning the fuel smooth and proper without any problem.
Conclusion:
That's all about carburetors, I hope you understand the definition, parts,types, working, functions, advantages, and disadvantages of the carburetor. If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.
Spark your brain and Throttle your knowledge.
What are Carburetors?
 |
| (carburetor) |
The carburetor is a device that is used for mixing the air and fuel in the correct and proper ratio of air-fuel mixture for an internal combustion engine for combustion. In general for burning the fuel inside the combustion chamber of an engine cylinder in all conditions we need a rich air-fuel mixture, to get such a rich air-fuel mixture we are using a device called Carburetor.
The main purpose of the carburetor is to regulate the air-fuel mixture ratio and by regulating that, it controls the speed of the engine since the speed of the engine depends upon the amount of air-fuel mixture passing inside the engine cylinder.
And also the main thing is that we are using the carburetors only in Petrol engines(SI engines) and not in diesel engines(CI engines). (Here SI stands for - Spark Ignition & CI stands for Compressed Ignition). Just read our post about the difference between Spark and compressed ignition engine for more clarification in differences between these ignition system.
Do you know, Why carburetors are used in petrol engines, not in diesel engines?
The carburetors are used only in Petrol engines i.e. Spark ignition because of the difference in the mode of combustion between Petrol and diesel engines.
In the case of a diesel engine, the fuel is burned when the fuel is injected at high pressure to the hot compressed air in the cylinder. This hot compressed air reaches the engine cylinder with the help of a turbocharger or natural respiration. And with the help of the Fuel pump, the fuel reaches the combustion chamber. And hence both fuel and air enter the combustion chamber separately. Thus with the help of that hot compressed air, the combustion process takes place in a diesel engine.
But in the case of a petrol engine, the combustion will occur only when the air-fuel mixture gets ignited by the spark from spark plug which is present inside the engine cylinder. This flow of air-fuel mixture is regulated and monitored by the carburetors.
So in petrol engines, we are using the mixture of fuel and air for the combustion process than a direct injection of fuel into the combustion chamber.
Thus to get that air-fuel mixture we are using Carburetors in Spark ignition(SI) or Petrol engines.
Parts of a Carburetor:
Ok, let's talk about the parts of the carburetors
So now, what are the parts of a Carburetor?
A simple carburetor is comprised of the following parts which are listed below:
- Throttle Valve
- Choke Valve
- Mixing Chamber
- Metering system
- Idling system
- Float Chamber
- Idle and Transfer port
- Venturi
- Strainer
Throttle Valve:
The throttle Valve is one of the most important parts of a Carburetor. It regulates the air-fuel mixture which is supplied to the engine cylinder. The throttle valve is opened when the driver throttled the accelerator.
Choke valve:
A valve that controls the air-fuel mixture is called a Choke valve. The primary function of the Choke valve is controlling the amount of air that is present inside the mixing chamber. The valve is remains opened partly, in the case when we are in need of a rich air-fuel mixture we can operate the valve and this valve remains very close to the inlet of the air passage, so we are able to get rich air-fuel mixture when we use this valve. We use this valve more in the rainy season because in those times is the engine will not get enough air to get started, so by using this valve we get rich air-fuel mixture to start the engine.
Mixing Chamber:
The mixing process of air and fuel takes place in this chamber and then supplied to the cylinder of the engine. Hence it is called a mixing chamber.
Metering system:
The flow of fuel into the nozzle is controlled by the metering system. The metering system is responsible for forming the correct air-fuel mixture.
It contains two important parts:
1. Metering orifice
2. Fuel discharge nozzle
When the air gets passes through the venturi, it creates a low-pressure field in the throat. Due to the difference in pressure, the fuel is discharged. The amount of fuel entering is controlled by the metering orifice and discharge hole at the exit of the fuel discharge nozzle.
What is the function of the nozzle tip in a carburetor?
The difference of level between the upper end of the main nozzle and float chamber fuel level is called nozzle lip.
The function of the nozzle tip is to reduce the overflow of fuel from the nozzle, the main nozzle end is usually kept at a higher level than the float chamber fuel level.
Idling system:
The idling system contains a passage directly from the float chamber to the Venturi tube. It creates a rich air-fuel mixture during the process of idling or throttling the accelerator up to 15%.
Float Chamber:
It acts as a storage tank of fuel for a continuous supply of fuel to the engine cylinder. It has a float valve that regulates the level of fuel in the float chamber. When the level of fuel decreases the float will move downwards so that the fuel supply valve opens and the flow of fuel takes place. If the fuel level increases, the float will move upwards and the fuel valves close so that the supply of fuel flow can be stopped.
Idle and Transfer port:
There are other two ports or nozzles present along with the main nozzle in the venturi for the supply of fuel to the engine cylinder called Idle and transfer ports or nozzles.
Venturi:
A hollow tube which helps to decrease the air pressure of the chamber for which the fuel comes out from the fuel pipe.
Strainer:
A component that is used for filtering the fuel before it gets enters the float chamber is called Strainer. It posses fine filters that remove the dust and other unwanted materials from the fuel. If these dust are not removed then, these specks of dust will block the nozzle.
Working of a simple carburetor
The Float and valves system maintains a constant level of fuel in the float chamber. The float chamber remains open in the atmosphere. The fuel from the fuel tank is supplied to the float chamber by using the fuel pump. The strainer now filters the fuel and removes the dust and unwanted materials from the fuel. Then this fuel is supplied to the main nozzle. The suction of air from the atmosphere takes place. This air passes through the venturi and it reduces the area of cross-section at the throat of the venturi.
Now the fuel is passed from the float chamber to a discharge jet tube which is at the tip of the throat of the venturi. Because of this, the pressure at the main nozzle and the velocity of the airflow increases. Due to the difference in pressure at the nozzle and the float chamber causes the formation of a mixture of atmospheric air and the fuel occurs. This difference in pressure at the float chamber and venturi is known as carburetor depression.
If we open the throttle valve more airflow will occur at the venturi tube and a large quantity of air and fuel mixture is supplied to the engine so that the engine can produce more power and also possess high speed, when close the throttle valve these actions takes place in the reverse way i.e. The quantity of air-fuel mixture reduces at venturi tube, so the power and speed of the engine get reduced.
Types of carburetors
So, let's start with the types of carburetors
what are the types of carburetors?
Based on the flow directions of the air-fuel mixture, the carburetors are classified into three basic types as follows:
what are the types of carburetors?
Based on the flow directions of the air-fuel mixture, the carburetors are classified into three basic types as follows:
1. Updraft carburetors
2. Horizontal or side-draft carburetors
3. Downdraft carburetors
Updraft carburetor
If the air supply is from the bottom side of the mixing chamber then it is called an updraft carburetor. The name itself will explain the working of this type, in updraft carburetors the air enters from the bottom side of the carburetor and moves towards the upside against the gravitational force, the fuel enters from the float chamber. Due to the difference in pressure between these two, chambers the venturi will mix the fuel that comes out from the float chamber with the inlet air and make the air-fuel mixture.
And then this air-fuel mixture is passed to the throttle valve which is directly connected to the accelerator, now this air-fuel mixture is passed to the engine cylinder where the combustion will occur when we rise the accelerator. The main disadvantage of this type is this type of carburetors has to lift the fuel droplets against gravitational force by air friction, and also the jet tube cross-section is small, because of these disadvantages these type of carburetors cannot supply the air-fuel mixture at high-speed.
Horizontal or side draft carburetor
If the air supply from the side of the carburetor then it is called horizontal draft or side draft carburetor. In horizontal or side-draft carburetors, the jet tube is placed in the horizontal direction. The air is coming in through one end of the carburetor and gets mixed with the fuel to form an air-fuel mixture. Then this air-fuel mixture is passed to the engine cylinder. Here also the throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. This resembles downdraft carburetor, when you rotate the downdraft carburetor in a horizontal direction then it is a horizontal draft or side draft carburetor. The advantage of this type is there is no airflow of resistance.
Downdraft carburetor
If the air is supply is from the upper side of the mixing chamber then it is called down-draft carburetor. In a downdraft carburetor, the air-fuel mixture enters the carburetor from the upside and moves towards the downside of the carburetor with the help of gravity. This type of carburetors is also works under the same principle due to the pressure differences between the two venturi the fuel comes out from the chamber mixed with the air. The air-fuel mixture is controlled by the choke valve. The throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. These type of carburetors allows the proper flow of air-fuel mixture to the engine cylinder. These carburetors help to operate engines at both high and low speed.
Which type of carburetors are widely used and why?
In most of the cases down-draft carburetors are generally used, because of the advantages as follows :
1. The flow of the air-fuel mixture is assisted by gravity, so the engine function is better at lower speeds under load.
2. We are able to achieve higher Volumetric efficiency when we use this type of carburetors.
Functions of a carburetor
The functions of a carburetor are :
1. The primary function of carburetors to produce an air-fuel mixture for combustion.
2. The speed of the engine is controlled by carburetors.
3. It maintains the ratio of air and fuel in the air-fuel mixture.
4. Maintaining a certain amount of fuel in the float chamber at all times.
5. To supply the correct amount of air-fuel mixture at the correct strength under all conditions of load and speed of the engine.
Advantages of the carburetor
1. Carburetor parts are cheap when compared to fuel injectors.
2. By using this, we can get more air-fuel mixture.
3. In the case of road tests, carburetors produce more power and precision.
Disadvantages of the carburetor
1. At low speed, the air-fuel mixture supplied by the carburetor is so weak and it will not
ignite properly.
2. The carburetor working may be affected by changes in atmospheric pressure.
3. Fuel consumption and air emissions are more when compared to fuel injectors.
4. Cost of maintenance is higher than the fuel injection system.
Applications of Carburetor
1. Used in Spark-Ignition Engine.
2. Used in controlling the speed of the vehicles.
3. Used to convert the main fuel(petrol) into fine droplets and it mixes the fuel with air for burning the fuel smooth and proper without any problem.
Conclusion:
That's all about carburetors, I hope you understand the definition, parts,
types, working, functions, advantages, and disadvantages of the carburetor.
If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.
Spark your brain and Throttle your knowledge.