| 摘要 |
Needle housing of simple springless syringe retracts into casing tube's barrel after use to avoid accidental needle sticks. A lip at the barrel's forward end and a far end of a rim of the needle housing together form a partial forward end wall. The plunger's plug is sealably and frangibly attached at forward end of plunger to interior portion of plunger and to an arm running lengthwise through plunger. An injection needle housing has a rim bonded to the exterior of the forward end of the syringe barrel, a projecting needle for injecting the fluid, an interior female cavity whose walls are shaped to sealably receive and lock the plug after the plug leaves the barrel during injection and a stabilizing lip containing breakaway points whose lower and upper portions are on each side of the partial forward end wall of the barrel. After injection of the fluid through the needle by pushing down on the plunger, a further push on the plunger causes the plug to breaks away from the plunger at breakaway points, leave the barrel and snugly lock into interior female cavity of needle housing. To retract the entire needle housing including a portion of a lip of the needle housing that breaks away with it, user manually pulls back on the plunger. After retraction, forward wall of barrel is not completely open to lessen chance of needle falling out of barrel and stick someone if it dislodges from its housing or from plug.
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