| 摘要 |
PURPOSE:To attain smooth rotation of gears by providing a groove on either or both a tooth side surface of gears or/and a surface of a pump chamber opposed to the tooth side surface so as to remove impurities contained in fluid into the groove. CONSTITUTION:There are provided on a tooth side surface of a drive gear 7 and a driven gear 8 ring-like grooves 14 coaxially with respective axes of the drive gear 7 and the driven gear 8. A clearance 15 between the tooth side surface of each gear 7 and 8 and a pump chamber 6 is set to such a value as to be required for rotation of gears in disregard of fine particles. Although fine particles contained in liqud to be fed tend to enter the clearance 15 during suction to discharge, they enter the groove 14 provided on the tooth side surface of the gears, thereby eliminating resistance to rotation of the gears. Entrance or accumulation of fine particles in the clearance 15 at a portion without the groove 14 is anticipated, however since the groove 14 is arranged near a space 16 defined between adjacent teeth of the gears, the fine particles are readily induced into the groove 14 and the space. Accordingly, the fine particles are sequentially moved to the groove 14 and the space, and are fed to a discharge port 11 to be discharged. Even when instantaneous reduction of rotation occurs, it is possible to prevent interference with practical use. |
