| 摘要 |
PURPOSE:To lengthen the service life of lubricant so as to improve the reliability of a burner fan by reducing the thermal conductivity from an impeller to the motor shaft bearing side by a sleeve for motor shafts, 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 opening 14 to be released to the atmosphere from an outlet 16. At this time, a cooling impeller 12 is rotating to cause the air in an opening 9 to be drawn and released in the circumferential direction of the cooling impeller 12. The air in the opening 9 draws air from an inlet 10 of a cooling duct 7 and is led out of the opening 9 after cooling the motor 17. 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 fact that the section area of a sleeve 18 is substantially smaller than that of the motor shaft B4B with a gap 19 interposed between the two motor shafts. As a result, the temperature of the bearing 5 of the motor 17 is significantly reduced.
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