Injection device for injection, especially self-administered injection, of medicament, including mechanisms for nulling and for selecting dosage, especially for use with multi-dose ampules

Injection device for performing dosed injections, said injection device defining a proximal end and a distal end, and having

• a housing (30, 32) for reception of an ampule or medication container (12) retaining a medicinal fluid, and a fluid expelling piston (17) movable in proximal direction within the ampule;
• an injection needle (16) engageable with the proximal end of the ampule and movable with the ampule in proximal direction with respect to the housing, in an injecting direction;
• an injection plunger (18) engageable against said piston (17);
• a plunger length setting mechanism (77) coupled to said plunger and forming with said plunger an injection dosing arrangement (18-77);
• a spring (95) coupled to the injection dosing arrangement (18-77);
• user operable spring cocking means (100);
• user operable spring release means (42, 104),
• said spring (95), after cocking, moving the plunger (18) of the injection dosing arrangement (18-77), upon release by the spring release means (41, 104) in engagement with said piston (17) to expel medicament fluid from the injection needle (16),
• wherein, in accordance with the invention,
• the plunger length setting mechanism (18-77) comprises
• a tubular element (77') having an internal thread;
• the injection plunger (18) includes an elongated stem (18") having an external thread (76) matching the internal thread of the tubular element (77) and telescopically receivable therein;
• a guide element (83) guiding said elongated stem (18"), and interengaging projection-and-recess means (82, 80) formed on said guide element and said elongated stem, respectively, to prevent relative rotation of the guide element and the plunger (18) while permitting relative axial movement of the guide element and said plunger;
• means (103, 104) for coupling the guide element (83) with the housing (32) of the device while preventing relative rotation of the guide element and the housing;
• and
• user operable setting means (56, 65, 100) coupled to the tubular element (77') of the plunger length setting mechanism for causing and controlling relative rotation (106) between said guide element (83) and said plunger length setting mechanism (77) to selectively control and change the overall length of said injection dosing arrangement (18-77) in accordance with the selected injection dosage.

In an injection device for injecting fluid medication from an ampule or container (12) having an ejection piston (17) for injecting the medication through a needle (16) coupled to the container upon axial movement of the piston,

• means for moving said piston including an injection dosing arrangement (18-77) of adjustable length,
• said injection dosing arrangement having a tubular element (77') formed with an inner thread, and a plunger means (18) having an elongated stem (18") formed with an external thread (76) matching said internal thread of the tubular element, said plunger means being engageable with the piston (17) in said ampule or container (12),
• comprising, in accordance with the invention,
• a guide element (83) rotatably coupled to said tubular element;
• a groove or slot (80) extending in axial direction formed in said elongated stem (18");
• projecting means (82) on said guide element (83) engageable with said groove or slot (80);
• interengaging projection-and-recess means (103, 104;
• 41) formed on said coupling element (83) and interiorly of a housing (32) of said device to permit relative longitudinal movement of said guide element within the housing while preventing relative rotation of the guide element (83) with respect to the housing (32);
• and
• means (65, 100) for rotating said internally threaded tubular element (77), whereby, upon rotation of said tubular element, said plunger means (18) will telescopically move into or out of said tubular element while being guided longitudinally within said housing.

In an injection device for injecting fluid medication from an ampule or container (12) having

• a housing for reception of said ampule or container (12);
• an ejection piston (17) for ejecting the medication through a needle (16);
• means for moving said piston (17) including an axially movable injection dosing arrangement (18, 77') of adjustable length, said injection dosing arrangement having
• a tubular element (77') formed with an inner thread, and a plunger means (18) having an elongated stem (18") formed with an external thread (76) matching said internal thread of said tubular element (77'),
• said plunger means being engageable with the piston (17) in said ampule or container (12),
• comprising, in accordance with the invention,
• means (80, 82, 83, 104) for restraining relative rotation of said plunger means (18) with respect to the housing (30) while permitting axial movement of said plunger means (18) within said housing (30);
• and
• user dosage setting means (56, 65) to effect relative rotation between said housing (30) and said tubular element (77') to control the amount of telescopic extension of said plunger means (18) from said tubular element (77') and hence the overall length of said injection dosing arrangement (18, 77').