| 摘要 |
A pre-compression pump ( 10 ) dispenses microdoses of fluid (F). The pump minimizes pulsing due to pressure fluctuations. The pump is provided with the following to limit pulsing: a low force slow return velocity return spring ( 46 ); enlarged fluid passage ( 58 ); elastic bumper ( 74 ); and, a rachet tooth ( 76 ) bearing against the stem ( 44 ). Further, a deflectable diaphragm ( 90 ), a splined ( 70 ) stem ( 44 ), no dip tube, and an off-center, gravitational low-point pump inlet ( 62 ) assist in printing the pump. The pump includes a stem ( 44 ) with deflectable fingers ( 92 ) to ensure sufficient momentum in pump operation. Detents ( 118 ) and grooves ( 120 ) selectively lock a nozzle cap ( 14 ) in an inoperative position. To ensure cleanliness, nozzle ( 60 ) cleaning is provided, wiping of the nozzle to remove meniscus (M) therefrom, cuts ( 104 ) formed in a shroud ( 98 ) assist in drawing excess fluid from the nozzle, and an empty volume ( 108 ) for collecting fluid run-off from the nozzle. A handle (H) is mounted to the pump providing a grip.
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