Constant Velocity (CV) carburetors are designed to maintain a consistent fuel mixture regardless of the air flow through the carburetor. They operate on a constant, fixed velocity. This is in contrast to variable or "conventional" carburetors, which regulate fuel flow based on fluctuating airflow.
Here's how CV carburetors work:
Vacuum Slide Mechanism: CV carburetors have a slide valve controlled by engine vacuum. The slide valve restricts or opens the air passage, regulating airflow into the carburetor.
Diaphragm: Beneath the slide valve, there's a diaphragm that connects to the vacuum chamber above the butterfly valve.
Fuel Jet: The main fuel jet is located near the venturi of the carburetor. Fuel is drawn through the jet by the air flowing through the carburetor.
Vacuum Piston: The CV carburetor also features a vacuum piston that moves in conjunction with the slide valve movement.
Principle of Operation:
CV carburetors utilize the Venturi effect to create suction at the fuel jet. As air flows through the venturi, a low-pressure area is created, drawing fuel from the main jet.
The engine's vacuum on both the intake manifold and the vacuum passage affects the slide valve and diaphragm.
As engine speed and airflow increase, the increased vacuum pulls the diaphragm upward. This raises the slide valve, allowing more air and fuel into the engine while maintaining the fuel mixture's consistency.
At lower engine speeds, the vacuum is weaker, allowing the diaphragm to rest, keeping the slide valve in a lower position. This decreases airflow and reduces the amount of fuel flowing through the jet, maintaining the consistent mixture.
Advantages of CV Carburetors:
They provide a precise and consistent fuel mixture at all engine speeds.
CV carburetors offer enhanced throttle response and reduced fuel consumption compared to some variable venturi carburetors.
They are less prone to flooding or fuel starvation issues at different engine loads.
CV carburetors are commonly found on various small-engined motorcycles and power equipment, where maintaining a steady fuel mixture is crucial for efficient operation.
