How do centrifugal fans in sweepers achieve the synergistic output of high negative pressure and high air volume to meet the dual demands of floor suction and long-distance transport?
Publish Time: 2025-09-16
In a sweeper's operating system, the centrifugal fan is not only the core component for generating airflow but also crucial to the overall cleaning performance of the machine. It faces a unique task: on the one hand, it must create sufficient negative pressure at the suction port to overcome floor friction and forcefully remove adhered dust, debris, and even fine particles; on the other hand, it must provide sufficient air volume to stably transport this debris through a long duct to the dust collection box, avoiding blockage or settling. This dual requirement of "high negative pressure" and "high air volume" may seem contradictory—typically, high negative pressure means high air velocity but limited flow, while high air volume is often accompanied by a drop in pressure. However, the centrifugal fan in modern sweepers achieves this synergistic output through sophisticated aerodynamic design and system integration.The key to achieving this balance lies in the coordinated design of the impeller and volute. The impeller, the "heart" of the fan, features blade shape, curvature, number, and inlet and outlet angles optimized through fluid dynamics to simultaneously increase the kinetic and pressure energy of the gas during high-speed rotation. The choice of backward- or forward-inclined blade configuration depends on specific operating requirements. Backward-inclined blades offer greater efficiency and stable operation at high pressures, making them suitable for applications requiring sustained negative pressure. Forward-inclined blades, on the other hand, achieve greater airflow within a limited space. By precisely calculating the blade's angle of attack and flow path length, the airflow is smoothly guided upon entering the impeller, minimizing impact losses. Centrifugal force accelerates and increases pressure, ultimately leading to the volute at high speed and high pressure.The design of the volute is also crucial. Its spiral involute structure does not simply enclose the impeller. Instead, through a gradually expanding flow path cross-section, it gradually converts the impeller's high-speed airflow into a stable static pressure while maintaining sufficient velocity to propel particles forward. This dynamic balance of pressure and velocity ensures that the fan generates strong suction at the suction port while maintaining sufficient air velocity within the duct, preventing waste from accumulating in bends or horizontal sections. The smooth finish of the volute's inner wall and the continuity of the flow path also reduce eddy currents and friction losses, improving overall efficiency.Furthermore, the fan's performance depends on its compatibility with the overall air duct system. The suction port shape, duct diameter, elbow angle, and dust box layout all influence airflow characteristics. A well-designed fan must work in harmony with these external factors. For example, an excessively large suction port area dilutes negative pressure, while a too small one restricts airflow. Therefore, the fan's performance curve must be aligned with the overall aerodynamic drag characteristics of the unit to ensure sufficient suction force and stable delivery capacity at the actual operating point.Material and structural reliability also support sustained output. In high-dust environments, the impeller is subjected to constant particle impact. If the material is not wear-resistant, the blade edges will quickly dull, leading to a decrease in aerodynamic performance. Therefore, impellers are often made of high-strength engineering plastics or metals, with surface treatments to enhance durability. Bearings and seals must effectively block dust intrusion to ensure the long-term stable operation of rotating components.As the sweeper moves along the ground, its suction port close to the ground and the fan running at high speed, the airflow, driven by the impeller, is flung toward the volute, creating a continuous low-pressure zone. This low-pressure zone acts like an invisible hand, firmly sucking up dust and debris from the ground, while the high-speed airflow, like an invisible conveyor belt, escorts them all the way to the dust collection area. This synergy of forces is not a simple addition, but the result of precise control. It enables the sweeper to not only tackle stubborn dust deep in carpets but also efficiently remove scattered debris from hard floors, truly achieving a comprehensive and in-depth clean.
