| 摘要 |
A multi-dose infusion pump employs a piston (20) sliding within the internal chamber (12) of a pump housing (10) to dispense liquid from a port (14). The peripheral surface (25) of the piston (20) has a sequence of steps (24, 26, 28) in a radial pattern spaced at intervals along the longitudinal axis of the chamber (12). A cap (50) is rotatably mounted to the pump housing (10) and includes a stop (52, 54) that limits forward movement of the piston (20) by engaging a selected one of the steps (24, 26, 28) on the piston (20) at each rotational position of the cap (50). This causes a series of predetermined quantities of liquid to be dispensed as the cap (50) is rotated to align the stop (52, 54) with each step (24, 26, 28) in sequence. A spring (40) between the cap (50) and piston (20) urges the piston (20) forward in the chamber (12) to dispense liquid from the port (14). The peripheral surface (25) of the piston (20) can also be equipped with a series of guide surfaces (34-36) that allow the piston (20) to be initially retracted toward the cap (50) without engaging the steps (24, 26, 28) while the cap (50) is in an initial rotational position, and then guide the stop (52, 54) along the steps (24, 26, 28) in a predetermined order as the cap (50) is rotated through a progression of rotational positions.
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