| 摘要 |
PURPOSE: An exhaust fan of an OTR(Over The Range) is provided to reduce BPF(Band Pass Filtering) noise in rotation of blades by setting the different angles of the left and right blades through different connecting angles between left/right rotatable shafts and left/right hubs. CONSTITUTION: A cavity is formed by an upper plate and a lower plate, and a component chamber having a magnetron and a cooling fan is mounted on the right of the cavity. An exhaust fan is mounted on the cavity. Each exhaust pipe is formed at both sides of a body to flow smoke and odor of food to the exhaust fan. The exhaust fan consists of a housing(52) having an exhaust port for discharging exhaust gas through the both opened sides, a drive motor(60) mounted in the center of the housing to generate drive force, both left and right hubs(58) connected with each left and right rotatable shaft(54,56) of the drive motor, and plural blades(62) formed outside the hubs with regular distances. The blades include long blades(68) and short blades(70) by each connecting plate(64) integral with the outside of the hubs. The short and long blades have different angles. Therefore, BPF noise is reduced in rotation of the blades.
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