| 摘要 |
PROBLEM TO BE SOLVED: To reduce a heat transfer amount from a pump shaft to a motor side and to suppress a temperature rise of a pump rotatably driving means by providing many holes for increasing thermal resistance at the shaft becoming a high temperature side to a thermal conduction direction from a molten solder, and providing a heat diffusing member at the shaft to become a low temperature side to the holes. SOLUTION: A pump 3 having an impeller 4 is constituted in a liquid of a molten solder 2 of a solder tank 1. Many through holes 20 are provided at an axial symmetry at a liquid surface side on a molten solder liquid surface of a pump shaft 5 to form an adiabatic diffusing part, and diffusing discs 22 are provided at an axial symmetry at a motor 7 side to form a diffusing unit. A rotation of a motor shaft 8 formed in this manner is transmitted to the shaft 5 through a joint 6. Thermal conductions from the pump 3 and the shaft 5 are reduced at the diffusing part having the many through holes 20, radiated at the diffusing units of the discs 22 and hence not almost conducted to the shaft 8. As a result, the motor 7 can be used at a low temperature to provide a long lifetime.
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