INJECTION DEVICE WITH RETAINER FOR PREVENTING UNINTENTIONAL MOVEMENT OF PISTON ROD Russian patent published in 2014 - IPC A61M5/315 

FIELD: medicine.

SUBSTANCE: invention refers to medical equipment, namely to injection devices. A device comprises a body, an injectable fluid container and a dose setting and injection mechanism. The mechanism comprises a piston rod, dose setting means and retainers. The piston rod axially moves during the dose injection, it has flat longitudinal outer surfaces slotted in an outer thread and arranged in parallel with each other on the opposite sides of the piston rod, and protected against a pivot in relation to the body. The dose setting means comprise a thread element having an internal thread and geared with the external thread of the piston rod. During the dose setting, the thread element turns about the piston rod to the body, and during the dose injection, it is kept from turning about the piston rod and the body so that the thread element and the piston rod together move axially in relation to the body. The retainers are fixed axially in relation to the body, contact the piston rod and prevent it from axial motion during the dose setting. The retainers are made of a bent metal wire, while clamping sections are bent with a convexity towards the piston rod, and the clamping sections of the retainers project with their respective wire convex areas into a hole of a guide element wherein the piston rod extends along the axis, and wherein it is kept from rotation by an interaction of the outer flat surfaces of the piston rod with the respective flat surfaces of the hole of the guide element.

EFFECT: invention enables avoiding formation of undesired drops generated at the needle tip when using the injection device.

14 cl, 7 dwg