Injection device

A device for delivering a plurality of preselected doses of a liquid drug from a loaded liquid reservoir (3), co-axially abutting against a plunger (5) at its upper end and a needle holder (7) at its lower end, having a first housing member (2) to accommodate the liquid reservoir (3) and a second housing member (1) coaxially and telescopically movably connected relative to the first housing member (2), and a drive stem (39) connected on the axis (36) of the device for reciprocal movement forward and backward exclusively by the same stroke distance l.sub.1 moveable into contact with the plunger (5) to cause the plunger (5) to advance to deliver doses of liquid from the liquid reservoir through the needle holder, the improvement comprising:

• means (11, 30, 32, 31, 35, 44, 29, 42, 50,) connected in said second housing member (1) and connected (9, 50, 25, 26) for rotative movement to both said first and second housing members (2, 1) to move the first and second housing members (2, 1) into each other by a selectable axial path l.sub.x ;
• said means including push button means (11, 30, 32, 31) connected for reciprocal movement in said second housing member (1) and said means (11, 30, 32, 31, 35, 66, 29, 42, 50) and having a portion (11, 30) projecting from said second housing member (1);
• said drive stem (39) connected at one end to said push button means (11, 30, 32, 31) and connected for reciprocal movement in said means (11, 30, 32, 31, 35, 44, 29, 42 50) to position the opposite end (41) of said drive stem (39) relative to the plunger (5) at an axial distance corresponding to the stroke path l.sub.1, and the opposite end (41) of said drive stem (39) extending from said means (11, 30, 32, 31, 35, 44, 29, 42, 50) into said first housing member (2) adjacent said plunger 5, whereby rotation of said means (11, 30, 32, 31, 35, 44, 29, 42, 50) by said push button means (11) by a selected amount moves said first housing member (2) into said second housing member (1) by a selected axial distance l.sub.x corresponding to the selected dose to be delivered thereby reducing the preset axial distance l.sub.1 between said opposite end (41) of the drive stem (39) and the plunger (5) to l.sub.1 -l.sub.x and causing the plunger (5) to be axially advanced by the amount of l.sub.x only upon reciprocally moving the drive stem (39) along its stroke path l.sub.1 by said push button means (11).