Air supply fan device

Abstract

An air supply fan device including: a fan casing disposed continuously to a combustion chamber containing a gas burner therein; an air supply fan contained inside of the fan casing, for supplying burning air to the gas burner; and a motor disposed outside of the fan casing, for rotating the air supply fan. The air supply fan device comprising: a ventilation hole formed by opening a fan casing constituting wall around a motor rotary shaft of the motor connected to the air supply fan; and a diaphragm valve body 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 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.

1 . An air supply fan device including: a fan casing disposed continuously to a combustion chamber containing a gas burner therein; an air supply fan contained inside of the fan casing, for supplying burning air to the gas burner; and a motor disposed outside of the fan casing, for rotating the air supply fan, the air supply fan device comprising:
 a ventilation hole formed by opening a fan casing constituting wall around a motor rotary shaft of the motor connected to the air supply fan; and   a diaphragm valve body 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 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.   
   
   
       2 . The air supply fan device according to  claim 1 , wherein the valve body is made of a rubber sheet, and further, is formed into a projecting or recessed shape in such a manner as to enlarge a pressure receiving area of a pressure receiving portion which receives an air pressure inside of the fan casing. 
   
   
       3 . The air supply fan device according to  claim 1 , wherein the inner diameter of the through hole is greater than the outer diameter of the motor rotary shaft, so as to define a clearance therebetween in the valve body when the inside and outside pressures of the fan casing are equal to each other.