Device for a medicament delivery device
The present invention relates to damper for a medicament delivery device, which device comprises a container containing medicament, a stopper arranged in said container and movable for expelling said medicament through a dose delivery means, a plunger rod having opposing proximal and distal ends and capable of acting on said stopper, and force means capable of exerting a force on said plunger rod, wherein said damper comprises a tubular sleeve having opposing proximal and distal ends; said sleeve comprises a compartment formed by a closed end wall at the proximal end of the sleeve and the proximal end of the plunger rod which is positioned in an open end at the distal end of the sleeve; and wherein said compartment comprises a sealable and resilient pad, a fluid, and at least one passage for expelling said fluid in an annular space between said sleeve and an inner wall of said container, thereby creating a dampening force, upon movement of said plunger rod.
1. A damper for a medicament delivery device that includes a container containing medicament, a stopper arranged in the container and movable for expelling the medicament through a dose delivery device, a plunger rod acting on the stopper, and a force device configured for exerting a force on the plunger rod, the damper comprising:
a tubular sleeve having opposing proximal and distal ends and comprising a compartment formed by a closed end wall at the proximal end of the tubular sleeve and a proximal end of the plunger rod which is positioned in an open end at the distal end of the tubular sleeve;
a high-viscosity fluid arranged inside the compartment;
at least one passage formed between the compartment and an annular space between the plunger rod and an inner wall of the container; and
a resilient and sealable pad positioned in the compartment and arranged to cover the at least one passage when the resilient and sealable pad is in a released position, wherein when the force device is activated for exerting a force applied on the compartment by the plunger rod for expelling medicament, the resilient pad is compressed such that the at least one passage is freed, expelling the high-viscosity fluid into the annular space between the plunger rod and the inner wall of the container, thereby creating a dampening force.
2. The damper of claim 1 , wherein at least one groove having a predetermined length axially extends on an outer circumference surface of the plunger rod forming at least one passage between a distal inner circumferential surface of the sleeve and a proximal outer circumferential surface of the plunger rod for allowing air entrapped inside the compartment to be expelled out through the at least one groove when a force is applied to the plunger rod.
3. The damper of claim 1 , wherein the resilient and sealable pad comprises an impermeable surface arranged against the high-viscosity fluid.
4. The damper of claim 3 , wherein at least one groove having a predetermined length axially extends on an outer circumference surface of the plunger rod forming at least one passage between a distal inner circumferential surface of the sleeve and a proximal outer circumferential surface of the plunger rod for allowing air entrapped inside the compartment to be expelled out through the at least one groove when a force is applied to the plunger rod.