PURPOSE: To reduce an enclosing quantity of a coolant by increasing mechanical strength of a heat collecting plate and reducing inside capacity of a heat collecting pipe, by a method wherein the heat collecting plate is constituted with a fin tube consisting of the heat collecting pipe and a heat collecting fin and a plurality of the heat collecting pipes whose outside diameter is made identical with each other and thickness is different from each other is used.
CONSTITUTION: As for a heat collecting plate, through a straight-lineform heat collecting pipe 8 is inserted into heat collecting fins 9 after the pressed heat collecting fins 9 have been arranged in line, a thin heat collecting pipe 8a and a thick heat collecting pipe 8b are inserted alternately at this time. Then, the heat collecting pipe 8 is expanded by a steel ball so that the outside diameter becomes the predetermined size and the heat collecting pipe 8 and the heat collecting fin are bonded to each other for securing. Then, after washing of the outside and the inside of the heat collecting plate, the heat collecting plate is completed by mounting a return bend 13 at opening ends of the heat collecting pipes 8 which are joined together by soldering. As the outside diameter of the heat collecting pipe 8 is fixed irrespective of its thickness, inner capacity of the heat collecting pipe for a coolant is reduced. With this construction, a coolant quantity existing within the heat collecting pipe can be reduced.
WATANABE TAKEJI
OUTAKE TATSUNORI
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