Plunger for Syringes and Syringes

Abstract

A plunger for a syringe may include a plunger head for fluid dense limiting a fluid chamber of the syringe, and a piston rod fixed to the plunger head. The piston rod may be formed by several longitudinally extending axial webs that have an outwardly radial extension from the longitudinal axis and lead into a common crossing section. A free activation edge, which radially protrudes the radial extension, may be provided on the piston rod and engageable with a vibration activator of a hollow body of the syringe to emit an acoustic signal. A swinging arm body may be arranged between two axial webs and couple the activation edge with the crossing section such that in case of a vibration activation in an axial direction the swinging arm body has a radial swinging arm length between the activation edge and the crossing section of at least 40% of the radial extension.

1 . A plunger for a syringe, which comprises a hollow body receiving the plunger, comprising a plunger head for sealing a fluid chamber of the syringe, and a piston rod fixed to the plunger head with an actuation section, at which the plunger can be actuated for inserting into the hollow body, wherein the piston rod is formed by axial webs extending along a longitudinal axis of the plunger, the axial webs having an outwardly radial extension r K  from the longitudinal axis and lead into a common crossing section, which receives the longitudinal axis, wherein at least one free activation edge, which radially protrudes the radial extension r K , is provided on the piston rod, which when inserting the plunger, is engageable with a vibration activator of the hollow body such that an acoustic signal is emitted, characterized in that a swinging arm body arranged between two axial webs couples the activation edge with the crossing section such that in case of a vibration activation in an axial direction the swinging arm body comprises a radial swinging arm length rS between the activation edge and a crossing section of at least 40% of the radial extension r K . 
     
     
         2 . The plunger according to  claim 1 , characterized in that the swinging arm body comprises a disc- or plate-shaped form, which extends in a circumferential direction and/or the swinging arm body structurally, except one free axial edge of the axial webs, merges into both axial webs and/or swinging arm body only merges into one of the both adjacent axial webs except one free axial edge of the axial webs and/or the swinging arm body is not connected to any of the axial webs. 
     
     
         3 . The plunger according to  claim 1 , characterized in that the swinging arm body comprises a circumferentially around the longitudinal axis extending plate-shaped form, whose thickness is smaller than substantially two times the thickness of the plunger. 
     
     
         4 . The plunger according to  claim 1 , characterized in that the swinging arm body is produced from one piece with the piston rod by injection molding with plastic and/or that the swinging arm body is formed by several plate-sections that are arranged parallel to each other. 
     
     
         5 . The plunger according to  claim 1 , characterized in that the at least one free activation edge extends in a circumferential direction particularly shaped in circular sections and/or the at least one free activation edge extends in a circumferential direction with a sector angle α of less than 100°. 
     
     
         6 . The plunger according to  claim 1 , characterized in that at least two activation edges are separately arranged on the same axial position of the piston rod, wherein the at least two activation edges of a same axial position are in sections diametrically opposite to each other and/or shaped in circular sections with a same circumferential extension. 
     
     
         7 . The plunger according to  claim 2 , characterized in that the axial webs radially protrude from the disc- or plate-shaped swinging arm body in an area of the sections of the axial webs adjacent to the axial webs, which are formed without an activation edge. 
     
     
         8 . A medical injection syringe, comprising the hollow body and the plunger according to  claim 1 . 
     
     
         9 . The plunger according to  claim 1 , characterized in that a radial overlap exists between the swinging arm body of the piston rod and the vibration activator of the hollow body so that the swinging arm body gets into radial engagement with the vibration activator when axially moving the plunger into the hollow body. 
     
     
         10 . The plunger according to  claim 9 , characterized in that an axial length of the vibration activator of the hollow body is designed with regard to an axial distance between two axially adjacent swinging arm bodies in such a way that the two adjacent swinging arm bodies are in engagement with the vibration activator. 
     
     
         11 . The plunger according to  claim 10 , characterized in that two in circumferential direction adjacent rows of several swinging arm bodies are offset in axial direction, wherein the axial offset is continuously the same size, wherein the axial offset is substantially equal to half of a distance between two in axial direction adjacent swinging arm bodies. 
     
     
         12 . The plunger according to  claim 5 , characterized in that the swinging arm body comprises a circumferentially over the sector angle α extending activation edge, and in the further progression two substantially straight setback edges, wherein the setback edges are not in engagement with the vibration activator and/or pass perpendicular to an axial longitudinal direction and/or lead in a recess that is incorporated into the axial web. 
     
     
         13 . The plunger according to  claim 1 , wherein the swinging arm body comprises a circumferentially around the longitudinal axis extending plate-shaped form, with a thickness of the plate-shaped form that is smaller than substantially one time a thickness of the plunger. 
     
     
         14 . The plunger according to  claim 1 , wherein the at least one free activation edge extends in a circumferential direction particularly shaped in circular sections and/or the at least one free activation edge extends in a second circumferential direction with a sector angle α of less than 90°. 
     
     
         15 . The plunger according to  claim 1 , wherein the at least one free activation edge extends in a circumferential direction particularly shaped in circular sections and/or the at least one free activation edge extends in a second circumferential direction with a sector angle α of between 5° and 90°. 
     
     
         16 . The plunger according to  claim 1 , wherein the at least one free activation edge extends in a circumferential direction particularly shaped in circular sections and/or the at least one free activation edge extends in a second circumferential direction with a sector angle α of between 10° and 60°. 
     
     
         17 . The plunger according to  claim 1 , wherein a radial overlap exists between the swinging arm body of the plunger and the vibration activator of the hollow body of between 0.05 mm to 0.5 mm, so that the swinging arm body gets into radial engagement with the vibration activator when axially moving the plunger into the hollow body.