Abstract The present invention provides for retractability of a hypodermic needle and for locking the retracted needle into position by making a limited number of alterations to a standard design of hypodermic syringe. Engagement means are provided on the head of the plunger for engaging and reversibly locking into a complementary recess on the hub housing the needle. The hub is threadedly received into an opening at the forward end of the syringe body. By employing the engagement means on the end of the plunger, the plunger may be used to remove and retract the needle from its fully deployed position into the interior of the body of the syringe. Alternatively, the engagement means can be used to replace the needle into position for reuse. Means for locking the retracted plunger into position include a spiral channel in the body of the syringe which receives one or more elastic radial vanes formed on the plunger. The spiral channel and radial vanes act in the same manner as the threads of a screw in order to reversibly lock the plunger into position. The spiral channel is provided with an end wall which provides a stop mechanism to prevent the plunger from being completely withdrawn once it has been inserted into the body of the syringe.
A safety syringe with retractable and lockable needle, comprising: a hollow cylindrical syringe body having a forward end and a rearward end; a plunger slidably disposed within said syringe body; elastic sealing means at the interior end of said plunger; engagement means formed at said interior end, said engagement means comprising a rectangular projection having four side faces, each of said side faces having an elastic protrusion; said syringe body further having an internally threaded forward opening and a sealing flange; a hypodermic needle mounted to an externally threaded hub sized so that said hub may be threadedly received into said forward opening and sealed against said sealing flange with said hypodermic needle projecting forwardly therefrom; said hub further having a rectangular rearward recess shaped to receive said rectangular projection, said rectangular rearward recess further having four side faces with a depression formed in each of said side faces of said recess sized and positioned to receive and reversibly lockingly engage with said elastic protrusions of said rectangular projection of said plunger; said syringe body further having a spiral channel formed at said rearward end comprising at least one complete circuit of said syringe body, said channel further comprising a bottom surface, a pair of side walls uniformly rearwardly increasing in depth with respect to said syringe body, and an end wall terminating said channel, said end wall being substantially orthogonal to said syringe body; and said plunger further having at least one elastic radial vane formed at the interior end of said plunger, said vane being sized and angled to ride within said spiral channel and disposed so that said plunger may be inserted into said syringe body by rotationally advancing said plunger in one direction only and after being inserted into said syringe body, said radial vane is received into said channel such that said plunger cannot thereafter be retracted beyond the point at which said radial vane encounters said end wall.
Claim 2
Dependent Claim
324 words
A safety syringe with retractable and lockable needle, comprising: a hollow cylindrical syringe body having a forward end and a rearward end; a plunger slidably disposed within said syringe body; elastic sealing means at the interior end of said plunger; engagement means formed at said interior end, said engagement means comprising a rectangular projection having four side faces, each of said side faces having an elastic protrusion; said syringe body further having an internally threaded forward opening and a sealing flange; a hypodermic needle mounted to an externally threaded hub sized so that said hub may be threadedly received into said forward opening and sealed against said sealing flange with said hypodermic needle projecting forwardly therefrom; said hub further having a rectangular rearward recess shaped to receive said rectangular projection, said rectangular rearward recess further having four side faces with a depression formed in each of said side faces of said recess sized and positioned to receive and reversibly lockingly engage with said elastic protrusions of said rectangular projection of said plunger; said syringe body further having a spiral channel formed at said rearward end comprising at least one complete circuit of said syringe body, said channel further comprising a bottom surface, a pair of side walls uniformly rearwardly increasing in depth with respect to said syringe body, and an end wall terminating said channel, said end wall being substantially orthogonal to said syringe body; and said plunger further having at least one elastic radial vane formed at the interior end of said plunger, said vane being sized and angled to ride within said spiral channel and disposed so that said plunger may be inserted into said syringe body by rotationally advancing said plunger in one direction only and after being inserted into said syringe body, said radial vane is received into said channel such that said plunger cannot thereafter be retracted beyond the point at which said radial vane encounters said end wall.