The different invention has resulted in various types of carburetor aiming to perform the same functions with different principles. A carburetor is a mechanism that atomizes and vaporizes gasoline and mixes it with air in different proportions to fit the changing conditions of spark-ignition engines. The combustible mixture is the air-fuel mixture obtained from the carburetor. The carburetor is the most critical component of a spark-ignition engine’s fuel system. Between the fuel filter and the induction, a manifold is where the carburetor is located. It provides an air-fuel mixture in various quantities according to the engine’s operating circumstances.
In this article, you’ll learn the various types of carburetors and their functions.
- 1 Types of carburetors
- 1.1 According to The Arrangement of Float Chamber
- 1.2 According to the direction of Air-Flow:
- 1.3 According to The Number of Units
- 1.4 According to The Type of Metering System
- 1.5 According to the type of Venturi
- 1.6 According to the Pressure above the Fuel in the float chamber
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- 1.8 According to the Types of Power System
- 1.9 According to the method of Varying the Mixture Strength
Types of carburetors
The various types of carburetors can be classified according to the followings:
According to The Arrangement of Float Chamber
Eccentric and Concentric are classified under these types of carburetors.
The float chamber is located on one side of the venturi tube in eccentric float chamber carburetors. When the vehicle is ascending a gradient, the eccentric float chamber type carburetor does not supply the correct air-fuel combination. The float chamber is positioned around the venturi tube in concentric float chamber carburetors.
According to the direction of Air-Flow:
Downdraft, Side draft, Updraft, and Semi-down draft are classified under these types of carburetors.
The air enters the carburetor at the top and exits through the side in side-draft carburetors. The air enters the carburetor from the bottom or side and exits from the top with an updraft carburetor. The airflow path is slanted from top to bottom in semi-downdraft carburetors.
The downdraft carburetor is utilized in most passenger cars. Gravity aids the passage of the mixture in this sort of carburetor. Thus, the engine sucks it better at lower speeds under load. The engine achieves a better volumetric efficiency. The carburetor is more easily accessible for inspection, change, or repair because it is located above the engine. The temperature of the air entering the carburetor is lower.
Read more: Understanding Solex Carburetor
According to The Number of Units
Single, Dual, and Four-barrel are the types of carburetors under this section.
There is only one barrel in a single barrel carburetor. Each barrel of a dual-barrel carburetor has a fuel jet, venturi tube idling system, choke, and throttle. It may have a single air inlet, choke, and float chamber, though two floats are often used, one for each jet. There is merely an accelerating pump on it. The carburetor has four barrels and is made up of two dual carburetors in one unit. A complete dual carburetor with a choke, an accelerating pump, a power valve, and a complete main metering and idle system on the primary side. The secondary unit contains a single float bowl, as well as a twin carburetor primary metering and idle system.
In most passenger car engines with eight or more cylinders, a dual carburetor and dual intake manifold are standard. One branch of the intake manifold is fed by each barrel of the dual carburetor. This design ensures that the fuel mixture is distributed evenly to the cylinders.
According to The Type of Metering System
Air-bleed jets and Metering rods are classified under these types of carburetors.
Fuel is delivered to the main discharge nozzle through the main metering jet at low speeds in air bleed jet carburetors. Carburetors come in a variety of shapes and sizes. carburetor with air bleed, the air is mixed with fuel when it is taken into the carburetor venturi through the air bleeds, which are connected to a vent tube inside the main discharge nozzle. More air is taken through the main air bleed as the suction of the main discharge nozzle increases at higher speeds, maintaining the correct air-fuel combination.
In carburetors with metering rods, the amount of gasoline is controlled by a rod that extends into the jet in metering rod carburetors. The metering rod is divided into three steps, each with a distinct diameter. This allows the fuel to travel through the space in the jet. A proper linkage connects the metering rod to the throttle shaft. When the throttle valve is opened, it is lifted, and when the throttle valve is closed, it is lowered. When the rod is lifted, greater space between the jet and the rod is created, allowing more fuel to travel to match the flow of ait at high speeds.
According to the type of Venturi
Plain venturi, Double venturi, Vane venturi, Nozzle-bar venturi, and Triple venturi are classified under these types of carburetors.
Carburetors are classed based on the number of ventures and the sort of ventures employed in their design. The venturi on the carburetor might be single, double, vane, nozzle-bar, or triple. Each type of venturi is designed to create a lower airflow pressure so that fuel can be drawn from the discharge jet. To avoid condensation, several vents help to keep the fuel away from the carburetor walls.
According to the Pressure above the Fuel in the float chamber
Unbalanced and Balanced systems are classified under these types of carburetors.
The carburetor is said to be imbalanced if the pressure above the fuel in the float chamber is equal to air pressure. It is said to be balanced when the pressure above the fuel in the float chamber equals the air intake in the air horn.
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According to the Types of Power System
Manually operated and Vacuum controlled are classified under these types of carburetors.
The carburetor is manually operated. The enhancement power jets are controlled by mechanical coupling to the throttle shaft. A vacuum-controlled power jet (also known as a step-up system) is used to enrich the mixture in a vacuum-controlled carburetor. A high vacuum is produced in the vacuum passages linked to the intake manifold while the engine is working properly at cruise speed, no-load. It pulls the vacuum piston down against the spring, which keeps the step-up (power) jet closed by holding the step-up rod in place.
When the engine is under load, the intake manifold vacuum drops, and the spring pulls the piston up, allowing excess fuel to flow from the float chamber to the discharge nozzle by raising the step up the rod out of the jet. The additional fuel is in addition to the typical quantity provided by the primary metering jet. As a result, the mixture is enriched.
Read more: Understanding Carter Carburetor
According to the method of Varying the Mixture Strength
Constant choke carburetor and Constant vacuum carburetor are classified under these types of carburetors.
The mixture strength in a constant choke carburetor is determined by the variable depression of a stationary tube or venturi. This type of carburetor includes Solex and Zenith. The choke tube depression in a constant vacuum carburetor is fairly consistent. And the size of the jet is changed to produce the correct mixture for all engine running situations. A constant vacuum carburetor is an example of S.U. the carburetor.
Watch the video below to learn more about carburetor:
Read more: Understanding Air Injection System
That is all for this article, where the various types of carburetors 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!