Injection device

Claim 1

A dispenser device for dispensing selectable amounts of liquid from an elongated cylindrical container (4) having a plunger (5) slidable forward therein from one end thereof for forcing liquid out of the container through an outlet in the opposite end of the container, comprising a drive mechanism (3) having an elongated rod member (12, 17), and a carrier element (20), and displacing means (10, 11, 26), said carrier element (20) being displaceable forth and back in the advancing direction of the plunger (5), said rod member (12, 17) connected to and carried by said carrier element (20) in such a way that it can be axially advanced with respect to the carrier element (20) in the advancing direction of the plunger (5) and is positively carried by the carrier element (20) in the forward as well as in the backward direction, said displacing means (10, 11, 26) being connected on the one hand to advance the rod member (12, 17) with respect to the carrier element (20) and on the other hand to advance and retract the carrier element (20) together with the rod member (12, 17) carried thereby with respect to the container (4), the rod member (12, 17) being adapted to abut and force the plunger (5) forward during activation of said displacing means (10, 11, 26) for advancing the carrier element (20) together with the rod member (12, 17) with respect to the container (4), housing means (1, 2), said cylindrical container (4) and said drive mechanism (3) connected in said housing means axially to each other, said displacing means (10, 11, 26) including a manually engageable element (11) extending from said housing means (1, 2), said rod member (12, 17) positioned to push the plunger (5) of the cylindrical container (4) forward and to move away from said plunger (5) leaving the latter in the forward pushed position, said displacing means (10, 11) connected for axially displacing said carrier element (20) by a constant stroke (h) forth and back in the advancing direction of the plunger (5) from a rearward rest position in said housing means (FIG. 2; FIG. 9) to a forward position (FIG. 3) axially toward the plunger (5), and back again into the rest position (FIG. 2; FIG. 9), said rod member (12, 17) on the one hand being axially advanceable by means of said displacing means (10, 11) with respect to said carrier element (20) in the advancing direction of the plunger (5) by any selected distance in correspondence with the plunger path, required for the desired quantity of liquid to be dispensed from said cylindrical container (4), and on the other hand said rod member (12, 17) being displaceable forth and back together with said carrier element (20) by said constant stroke (h) by said displacing means (10, 11), whereby said rod member (12, 17) located at a distance from the plunger (5) in the rest position (FIG. 2; FIG. 9) of the carrier element (20) can be axially moved, by means of said displacing means (10, 11), relative to the carrier element (20) remaining in the rest position (FIG. 2; FIG. 9), in the advancing direction by the selected axial distance without abutting against the plunger (5), and abuts during actuation and displacement (h) of the carrier element (20) from the rest position (FIG. 2; FIG. 9) into the forward position (FIG. 3) against the plunger (5) at the moment, when the carrier element (20) has been axially displaced by the difference between the constant stroke (h) and the selected distance, when the displacement of the carrier element (20) is continued up to the forward position (FIG. 3), and means (26) connected to move said carrier element (20) and rod member (12, 17) away from the plunger (5) by the constant stroke (h) leaving the plunger (5) in the forward pushed position, while displacing the carrier element (20) back from the forward position (FIG. 3) into the rest position (FIG. 2; FIG. 9).