| 摘要 |
An air supply fan device (2) including: a fan casing (20) disposed continuously to a combustion chamber containing a gas burner therein; an air supply fan (21) contained inside of the fan casing, for supplying burning air to the gas burner; and a motor (22) disposed outside of the fan casing, for rotating the air supply fan. The air supply fan device comprising: a ventilation hole (26) formed by opening a fan casing constituting wall around a motor rotary shaft (23) of the motor connected to the air supply fan; and a diaphragm valve body (3) which is fixed to the ventilation hole and has a through hole, through which the motor rotary shaft is inserted, opened at the center thereof. The valve body being formed into a shape such that a gap (35) is defined between the through hole and the motor rotary shaft when the inner pressure inside of the fan casing is negative during the rotation of the air supply fan while the gap is closed in tight contact of the peripheral edge of the through hole with the motor rotary shaft when the inner pressure inside of the combustion chamber or the fan casing is positive. |
