| 摘要 |
The present invention overcomes deficiencies in the art. A valve device is provided that includes a valve body defining a chamber for receiving fluid to be dispensed from the valve device, a seal contact surface located on the valve body, near a location where fluid discharges from the chamber, one or more grooves within the seal contact surface, and a reciprocatable piston rod supporting a seal that selectively contacts the seal contact surface, the piston rod being received at least partially within the chamber. The groove and seal have structural configurations that prevent the seal from fully blocking the groove when the piston rod is in a first position where the seal contacts a portion of the seal contact surface including the groove, and as a result fluid within the chamber may enter the groove when the piston rod is in this first position. A method of dispensing fluid in variable amounts is also provide that includes the steps of providing a valve device as described above, repeatedly moving the piston from the first position to the second position, thus allowing fluid within the chamber to enter the groove and then be swept out of the valve device in a dropwise manner.
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