| 摘要 |
PURPOSE:To maintain rolling contact having an accurate pitch curve on an engagement surface and to reduce the wear and noises of tooth flanks by providing a backlash only to nonengagement surfaces of a couple of noncircular gears which engages each other and rotate in proportion to a flow rate. CONSTITUTION:The noncircular gear in a positive displacement flowmeter which has a reference pitch curve PS is put in torque driving and driven operation by inversion. A driving noncircular gear and a driven side noncircular gear engage each other on flanks A from a tooth form T1 nearby the part of a minor axis rs which is the maximum torque point of the driving side noncircular gear to a tooth form Tn with a major axis rl where the driven side noncircular gear changes into a driving side in a next period and engage the minor axis gear at the maximum torque point. Opposite flanks B, therefore, become nonengagement flanks. An involute tooth form shown by a solid line is provided with a backlash on flanks of a tooth form B as shown by a dotted line. Thus, the rolling contact with the accurate pitch curve is maintained on the engagement surface and the wear and noises of the flanks are reducible.
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