Centrifugal fan structure

2025-08-15

1. Impeller

- A core component that performs work, typically composed of a hub, blades (backward-curved, forward-curved, radial types, etc.), and a cover plate, often made of cast iron, steel, or alloys.

- Function: By high-speed rotation (driven by an electric motor), it agitates the gas, utilizing centrifugal force to impart kinetic and pressure energy to the gas, which is crucial for gas pressurization.

2. Casing (Volute)

- Usually a spiral-shaped metal casing (snail-shell-like), matching the impeller material (such as ordinary steel, wear-resistant steel, fiberglass, etc.).

- Function: It collects the gas thrown out by the impeller, converting the kinetic energy of the gas into static pressure energy through the gradually expanding cross-sectional area of the spiral passage, while guiding the gas to exit from the discharge port.

3. Inlet (Suction Port)

- Typically conical or bell-shaped structure, installed at the axial inlet of the impeller.

- Function: It guides the gas to enter the impeller smoothly and uniformly, reducing airflow impact and vortices, thereby improving intake efficiency.

Secondary auxiliary components (ensuring stable operation and adapting to scenarios):

1. Drive System

- Includes main shaft, bearings, couplings (or pulleys + belt):

- Main Shaft: Connects the impeller to the drive components, transmitting torque;

- Bearings: Support the main shaft, reducing rotational friction (mostly rolling bearings, some large fans use sliding bearings);

- Couplings/Pulleys: Connect the main shaft to the motor output shaft (couplings provide direct transmission, pulleys offer indirect transmission via belts, allowing speed adjustment).

2. Motor

- The power source for the fan, matched according to the fan's power and speed requirements (such as asynchronous motors, explosion-proof motors, high-temperature resistant motors, etc.), usually connected to the impeller via the drive system.

3. Other Optional Components

- Control Devices: Such as inlet guide vanes (installed at the inlet, adjusting blade angle to regulate airflow and pressure) and outlet valves (controlling exhaust volume);

- Sealing Devices: Such as shaft seals (preventing gas leakage from the gap between the main shaft and casing, or external dust ingress);

- Vibration Dampening Devices: Such as base vibration pads, bearing housing dampers, reducing operational vibrations;

- Cooling Systems: For high-temperature operating condition fans, such as bearing cooling sleeves, motor cooling fans, preventing component overheating;

- Mufflers: Installed at the inlet/outlet, reducing airflow noise (suitable for noise-sensitive environments).