Single suction type centrifugal fan

Abstract

A single suction type centrifugal fan includes: a casing (2) provided with a spiral tube having a spiral shape; and an impeller (4) housed in the casing (2) and provided with a plurality of blades (3) and an impeller main plate (13) to which the blades (3) are fixed. The casing (2) includes a suction side plate (6) having a suction port (5), and a motor fixing side plate (9) to which a motor (8) is fixed. A center portion of the impeller main plate (13) is fixed to the motor (8), and a main plate opening (18) is formed in the impeller main plate (13) between the blades (3) and a center portion of the impeller main plate (13). A plane which passes end portions of the blades (3) on a side of the motor fixing side plate (9) and is perpendicular to a rotary shaft (12) of the motor (8) is assumed as a blade end portion imaginary plane (20). A constriction portion (21) is formed where a distance between the blade end portion imaginary plane (20) and the motor fixing side plate (9) is narrowed between the main plate opening (18) and the blades (3).

Description

technical field [0001] The present invention relates to a configuration of a single-suction centrifugal fan used in ventilation equipment such as a duct fan or an air conditioner. Background technique [0002] In recent centrifugal fans, due to the complexity of the connected piping and the high airtightness of the building, a high static pressure of the equipment is required. As a structure for increasing the static pressure of a conventional single-suction centrifugal fan, it is known to provide a turbulence suppressing plate arranged in the vicinity of the tongue portion on the inner peripheral portion side of the blades of the impeller and extending in the radial direction of the impeller. [0003] Below, refer to Figure 5A , Figure 5B , the conventional example will be described. [0004] like Figure 5A , Figure 5B As shown, the single-suction centrifugal fan 101 includes a casing 102 and an impeller 103 built into the casing 102 . The casing 102 includes a suct...

AI Technical Summary

Problems solved by technology

However, since the turbulence suppression plate 116 is arranged in the air passage, the performance (PQ) curve is on the open side, that is, when the outflow air volume is large, airflow noise caused by the collision between the airflow and the turbulence suppression plate 116 is likely to occur.

In addition, since the turbulence suppressing plate 116 and the blade 115 of the impeller 103 are disposed close to each other, machining accuracy and assembly accuracy of parts are required, and there is a problem of increased processing costs and assembly man-hours.