| 摘要 |
PURPOSE:To lengthen the service life of lubricant and improve the reliability of a burner fan by reducing the thermal conductivity from an impeller to the motor shaft bearing side by means of a motor shaft coupler having a low thermal conductivity and drawing in low-temperature air through a cooling duct to cool the motor inside. CONSTITUTION:When a motor 17 rotates, the exhaust gas in the water heater is drawn from an air intake 14 to be released to the atmosphere from an outlet 16. At this time, an impeller 12 which is fixedly attached to a motor shaft 4 rotates to draw the air in an opening 9 and discharge the air in the circumferential direction of the cooling impeller 12. The air in the opening 14 draws air from an inlet 10 of a cooling duct 7, and, after cooling the motor 17, is drawn out of the opening 9. The heat conducted from an impeller 15, which has been heated by exhaust gas, to a motor shaft B4B is hard to be conducted on to a motor shaft A4A because of the thermal conductivity of a coupler 18 which is substantially smaller than that of the motor shafts 4A, 4B. As a result, the temperature of the bearing 5 of the motor 17 is significantly reduced.
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