Shroud deployment in automatic injection devices

Abstract

Exemplary embodiments provide automatic injection devices in which a shroud is automatically deployed to protectively sheath a needle after an injection is performed. Exemplary embodiments also provide shroud deployment assemblies including a shroud and a syringe carrier that, when cooperatively configured in an automatic injection device, ensure that the shroud is automatically and completely deployed after an injection is performed using the automatic injection device. Exemplary embodiments are also configured to ensure that, once the shroud is deployed to an extended position to sheath the needle, accidental forces applied to the shroud do not succeed in subsequently retracting the shroud to a retracted position in which the needle would become exposed.

What is claimed is: 
     
         1 . A syringe carrier assembly for use in an automatic injection device, the syringe carrier assembly comprising:
 a proximal tubular portion having a first outer diameter;   a distal tubular portion having a second outer diameter less than the first diameter; and   a chamfer formed between the proximal and distal tubular portions to create a relief extending between the proximal tubular portion and the distal tubular portion;   wherein the syringe carrier assembly is disposed partly within a tubular member of a shroud;   wherein, as the shroud moves from a retracted position to an extended position, distal arms of the shroud move forwardly within a constrained space formed between an inner portion of the housing of the automatic injection device and an external portion of the proximal tubular portion of the syringe carrier; and   wherein the proximal tubular portion and/or a chamfered edge of the syringe carrier assembly are cooperatively coupled to exhibit a gradual downward force slope substantially along a distance from a retracted position to a deployed position.   
     
     
         2 . The syringe carrier assembly of  claim 1 , wherein the height of the constrained space is configured to be at least equal to a thickness of the distal arms of the shroud. 
     
     
         3 . The syringe carrier assembly of  claim 1 , wherein an outer diameter of the proximal tubular portion of the syringe carrier assembly is configured to range from about 13.0 mm to about 14.0 mm. 
     
     
         4 . The syringe carrier assembly of  claim 1 , wherein the chamfered edge has an angle ranging from about 5 degrees to about 60 degrees. 
     
     
         5 . The syringe carrier assembly of  claim 1 , wherein the proximal tubular portion of the syringe carrier assembly comprises:
 a slot formed in an outer surface of the proximal tubular portion to create a depression or trough in the outer surface.   
     
     
         6 . The syringe carrier assembly of  claim 1 , wherein the slot has a depth ranging from about 0.1 mm to about 0.5 mm. 
     
     
         7 . An automatic injection device, comprising:
 a housing having an internal bore extending between a proximal end and a distal end, the internal bore including a flange having diametrically opposed openings therein; and   a shroud disposed within the internal bore at the proximal end of the housing of the automatic injection device, the shroud movable between a retracted position and an extended position relative to the housing, the shroud comprising:
 a tubular member extending between a proximal end and a distal end, and 
 one or more arms extending from the distal end of the tubular member; and 
   wherein, as the shroud is deployed from the retracted position to the extended position, the arms of the shroud move forwardly through the diametrically opposed openings in the flange of the housing,   wherein the flange is configured to minimize engagement of the arms with an edge of the flange to facilitate movement of the arms of the shroud through the opening of the flange during deployment of the shroud.   
     
     
         8 . The automatic injection device of  claim 7 , wherein the flange is configured to minimize bending of the arms of the shroud. 
     
     
         9 . The automatic injection device of  claim 7 , wherein the portion of the flange abutting the opening is removed to increase the width of the opening. 
     
     
         10 . The automatic injection device of  claim 9 , wherein a length of the removed portion of the flange ranges from 0.05 mm to 0.6 mm. 
     
     
         11 . The automatic injection device of  claim 7 , wherein, once the shroud is deployed to the extended position, the shroud is configured to withstand a force of at least 80 N without retracting to the retracted position. 
     
     
         12 . The automatic injection device of  claim 7 , wherein the automatic injection device comprises a dose of a TNFα inhibitor. 
     
     
         13 . The automatic injection device of  claim 7 , further comprising:
 a syringe carrier coupled to and disposed partly within the tubular member of the shroud, the syringe carrier comprising a cylindrical portion having a slot formed in an outer surface of the cylindrical portion to create a depression or trench in the outer surface extending along a length of the syringe carrier;   wherein the slot increases a constrained space formed between an inner portion of the housing of the automatic injection device and an external portion of the cylindrical portion of the syringe carrier.