CPC A61M 5/31551 (2013.01) [A61M 5/31575 (2013.01); A61M 5/31585 (2013.01); A61M 2005/3126 (2013.01); A61M 5/31541 (2013.01); A61M 2205/581 (2013.01); A61M 2205/582 (2013.01)] | 5 Claims |
1. A liquid pharmaceuticals delivery device (18) comprising a cylindrical main body (1), a cartridge (3) having a mainly cylindrical inner cavity with a volumetric capacity for accommodating multiple doses of a liquid pharmaceutical, the cartridge (3) comprising a first end for receiving a plunger (7) and a second end for liquid pharmaceutical extraction, the plunger (7) having a circumferential portion shaped and sized to correspond to the transversal section of the cartridge (3), wherein the device is characterized by further comprising:
a jackscrew (55) comprising a threaded lower jackscrew (5) and a threaded upper jackscrew (6) integrated to each other, the jackscrew (55) being rotatable around a longitudinal primary axis (16) of the cylindrical main body (1) and stationary along said longitudinal primary axis (16),
a threaded plunger rod (8) integrated to the plunger (7) and having a thread diameter (Dp), which is smaller than the thread diameter (Ds) of the spindle (10), corresponding to the thread diameter of the lower jackscrew (5), the plunger rod (8) being in threaded communication with the lower jackscrew (5) and moving inside a lower bearing (4), wherein the lower bearing (4), together with plunger rod (8) and lower/upper jackscrews (5, 6), stays in permanent contact with the cartridge during dose setting and delivery in order to guarantee dosing accuracy as the force transmission to the cartridge (3) and plunger rod (8) is supported by a flange (20) of lower jackscrew (5) and the lower bearing (4), independent from the main body (1),
the spindle (10) having threads and a thread diameter (Ds), which is greater than the thread diameter (Dp) of the plunger rod (8), corresponding to the thread diameter of the upper jackscrew (6), the spindle (10) being in threaded communication with the upper jackscrew (6), wherein the threads on the spindle (10) and the threads on the plunger rod (8) are working in the same rotational direction in order to reduce the operational friction and the threads on the spindle (10) have a pitch distance greater than a pitch distance of the threads on the plunger rod (8),
a button (12) engageable with the spindle (10), by one thereof having a recess and the other having a protrusion matching said recess along a direction parallel to the primary axis of the spindle (10), and
a resilient means (17) normally keeping the button (12) in a disengaged position from the spindle (10), wherein said recess and protrusion are kept away from each other by the resilient means (17), and the engaged position is available by pushing and moving the button (12) against the force of the resilient means (17), and
wherein a segment of the threads of the spindle (10) corresponding to threads of a traveler (15) has a pitch distance that is smaller than a pitch distance of the threads of the plunger rod (8).
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