Safety Syringe and Needle and Needle Seat Retracting Device of Safety Syringe

Abstract

A safety syringe has a barrel, a pushing element, a retracting element, and a needle group. The barrel is hollow and has a needle-group mounting end, an operating grip end, and a barrel lumen. The pushing element is retractably mounted in the barrel lumen and has a pushrod chamber. The retracting element is airtightly and slidably mounted in the pushrod chamber. The needle group is connected to the needle-group mounting end of the barrel. The present invention can pull the retracting element to move relative to the pushing element to form a low pressure condition in the pushrod chamber as a vacuum status. After the injection, a vacuum attraction force in the pushrod chamber can retract the used needle group into the pushrod chamber for safe use of the safety syringe.

What is claimed is: 
     
         1 . A needle and needle seat retracting device of a safety syringe having a barrel and a barrel lumen formed in the barrel, and comprising:
 a pushing element airtightly and slidably mounted in the barrel lumen of the barrel, and having
 a pushing rod having
 a diameter; 
 a pushrod chamber formed in the pushing rod; 
 a front drug pushing end slidably mounted in the barrel lumen and having a diameter smaller than the diameter of the pushing rod; 
 a rear operating end being opposite to the front drug pushing end and extending out of the barrel lumen; 
 a first interior ring annularly formed on and protruding from an inner wall of the pushing rod adjacent to the front drug pushing end; and 
 a second interior ring annularly formed on and protruding from an inner wall of the pushrod chamber of the pushing rod adjacent to the rear operating end; 
 
 an inner airtight stopper airtightly and securely mounted in the front drug pushing end of the pushing rod, and airtightly mounted in the pushrod chamber; 
 an outer airtight stopper securely connected to the front drug pushing end and the inner airtight stopper, and airtightly and slidably mounted in the barrel lumen; and 
 an end cover securely mounted on the rear operating end of the pushing rod and having a holding tube formed on and through a center of the end cover; and 
   a retracting element airtightly and slidably mounted in the pushrod chamber of the pushing rod and having
 a pulling rod having
 a gripping end extending out of the pushrod chamber through the holding tube of the end cover; and 
 an engaging end being opposite to the gripping end and extending in the pushrod chamber; and 
 
 an airtight spigot securely connected to the engaging end of the pulling rod and selectively adjacent to the inner airtight stopper. 
   
     
     
         2 . The needle and needle seat retracting device as claimed in  claim 1 , wherein the inner airtight stopper has a connecting segment being centrically grooved and formed in a front end of the inner airtight stopper. 
     
     
         3 . The needle and needle seat retracting device as claimed in  claim 1 , wherein the inner airtight stopper has a connecting segment being cylindrical, centrically formed on and protruding from a front end of the inner airtight stopper. 
     
     
         4 . The needle and needle seat retracting device as claimed in  claim 1 , wherein
 the inner airtight stopper is a step block and has
 a protruding segment formed on the front end of the inner airtight stopper, airtightly and securely connected to the front drug pushing end, and having a diameter; 
 an engaging segment formed on a rear end of the inner airtight stopper and extending into the pushrod chamber, formed with the protruding segment, and having
 a diameter larger than the diameter of the protruding segment; and 
 an outer wall; and 
 an annular recess annularly formed on the outer wall of the engaging segment, and airtightly engaging the first interior ring of the pushing rod; and 
 
 an unplug recess formed in a rear side of the engaging segment; and 
   the inner airtight stopper has a connecting segment formed in a front side of the protruding segment.   
     
     
         5 . The needle and needle seat retracting device as claimed in  claim 4 , wherein
 the pushing rod has a mounting segment formed around the front drug pushing end; and   the outer airtight stopper is mounted around the mounting segment of the pushing rod, is airtightly connected to the protruding segment of the inner airtight stopper, and is airtightly and slidably mounted in the barrel lumen of the barrel.   
     
     
         6 . The needle and needle seat retracting device as claimed in  claim 4 , wherein the outer airtight stopper of the pushing element is airtightly connected to the front drug pushing end, is airtightly connected to the protruding segment of the inner airtight stopper, and is airtightly and slidably mounted in the barrel lumen of the barrel. 
     
     
         7 . The needle and needle seat retracting device as claimed in  claim 4 , wherein
 the pushing rod has an inner ring annularly formed in the front drug pushing end; and   the protruding segment of the inner airtight stopper has
 an outer wall; and 
 a concave groove annularly formed on the outer wall of the protruding segment, and airtightly engaging the inner ring of the front drug pushing end of the pushing rod. 
   
     
     
         8 . The needle and needle seat retracting device as claimed in  claim 4 , wherein
 the front drug pushing end of the pushing rod has a screwed segment; and   the outer airtight stopper is airtightly screwed with the screwed segment of the front drug pushing end, is airtightly connected to the protruding segment of the inner airtight stopper, and is airtightly and slidably mounted in the barrel lumen of the barrel.   
     
     
         9 . The needle and needle seat retracting device as claimed in  claim 8 , wherein
 the inner airtight stopper is composed of a protruding section and an engaging section;   the protruding section has
 an outer wall airtightly engaging the outer airtight stopper 
 a rear side; and 
 a threaded portion formed in the rear side of the protruding section; 
   the engaging section is threaded with the protruding section to form the inner airtight stopper, and has
 a front side; 
 an outer wall; 
 a screwed portion formed on and protruding from the front side of the engaging section and securely threaded with the threaded portion of the protruding section; and 
 an annular trough formed in the outer wall of the engaging section and airtightly engaging the first interior ring of the pushing rod in the pushrod chamber; and 
   the connecting segment is formed on a front side of the protruding section.   
     
     
         10 . The needle and needle seat retracting device as claimed in  claim 1 , wherein
 the pulling rod is an elongated rod with multiple protruding ribs formed on an outer surface of the pulling rod, and has a front end and a rear end;   the engaging end of the pulling rod is formed on the front end of the pulling rod and has
 an outer surface; and
 multiple engaging panels formed around the outer surface of the engaging end and spaced apart at intervals; and 
 
   the gripping end is formed on the rear end of the pulling rod, is opposite to the engaging end, and extends out of the pushrod chamber through the end cover; and   the pulling rod has a depressed gap annularly formed in the outer surface of the pulling rod to serve as a forcing point for breaking the pulling rod.   
     
     
         11 . The needle and needle seat retracting device as claimed in  claim 10 , wherein
 the holding tube of the end cover has
 an inner end; and 
 a retaining flange formed on and protruding from the inner end of the holding tube; and 
   the engaging end of the pulling rod has an engaged flange formed on the outer surface of the engaging end between the engaging panels and the depressed gap, and selectively engaging the retaining flange of the holding tube of the end cover.   
     
     
         12 . The needle and needle seat retracting device as claimed in  claim 11 , wherein a low pressure condition in the pushrod chamber is formed by the movement of engaging end of the pulling rod engaging the airtight spigot, the retracting element moving backward by pulling the gripping end, and the engaging end of the pulling rod engaging the retaining flange of the holding tube of the end cover.