Passive injection device with automatic securing means

An injection device comprising a cylindrical body (3) enclosing a reservoir (9) containing a product to be injected, which is slidably mounted in the body (3), which is open at one end on an injection needle (11) and is closed at another end by a plunger (16) mounted so as to be movable in translation in the reservoir under the action of a plunger rod (17) provided with a control member comprising a cylindrical cap (19) which is slidably mounted on the body (3), the plunger rod (17) being secured by a proximal end to the bottom of this cap (19) and passing through an element mounted so as to be movable in translation in the cap, the movable element comprising a nut (21) into which the plunger rod (17) is screwed, the cap being moved axially to engage the nut and then rotated to deliver the dose, the surface of the distal end (3a) of the body (3) being coated with adhesive means capable of ensuring that this surface is held on the skin (4) of a patient wherein the injection device comprises means for securing the needle in a retracted position within said cylindrical body after use, the activation of said securing means being ensured by the adhesive means when a withdrawal effort is exerted on the injection device while the distal end (3a) of the body (3) is maintained on the skin (4) of a patient by said adhesive means, said injection device being free of a spring mechanism.