| 摘要 |
PURPOSE:To reduce the leak amount of fluid and improve the accuracy in flow-rate metering by making the top-part thickness of the gear tooth in the major-axis part of a plurality of noncircular gear bodies larger than that of other gear, and forming a concaved part which is engaged with the gear tooth in the major-axis part, into the minor-axis part. CONSTITUTION:The top part-thickness (a) of the gear tooth 14 at the major- axis part of a noncircular gear body 11 is made larger than the top-part thickness (b) of other gear tooth 15, and the addendum 14a of the gear 14 is formed into circular from having the center 0 of revolution of the noncircular gear body 11 as center of curvature. A concaved part 16 which can be meshed with the gear 14 in the major-axis part 12 is formed into the minor-axis part 13 of the noncircular gear body 11. The gear 14 of the major-axis part 12 shifts along the inner peripheral surface 17a of a casing 17, and a certain gap 18 is formed between the addendum 14a and the inner peripheral suface 17a, and the gap width (c) equal to the top-part thickness (a) can be obtained. Therefore, the flow resistance of the fluid which tends to leak through the gap 18 is increased by the gap width (c), and the leak amount can be reduced.
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