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Suction syringe with an automatic locking means

  • US 4,758,232 A
  • Filed: 09/08/1987
  • Issued: 07/19/1988
  • Est. Priority Date: 09/08/1987
  • Status: Expired due to Term
First Claim
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1. A suction syringe for facilitating blood withdrawing operation by use of a vacuum produced and retained therein in advance, comprising:

  • a barrel having a bore therethrough, a distal end of said barrel adapted to be connected to a hollow needle, said bore being open at the proximal end of said barrel; and

    a plunger slidably positioned in said bore providing at its forward end a fluid tight seal against the wall of said barrel, said plunger having a rearward portion extending longitudinally outwardly beyond the proximal end of said barrel;

    characterized in thatthe inner periphery of said bore at said proximal open end is provided with at least two chamfered portions and at least two un-chamfered portions in an alternative and equally spaced manner; and

    thatat least two radially deformable elastic portions corresponding, in number and angular positions, to said chamfered portions of said bore in said barrel are integrally formed with said plunger rearward of said piston;

    said elastic portions being depressed and completely received within said bore when said plunger is pushed into said bore, and extending radially outwardly and engaging at said un-chamfered portions of the proximal end of said bore when said plunger is pulled rearwardly to a location where the depression force of said bore of said barrel against said elastic portions of said plunger is released;

    whereby said plunger, when pulled rearwardly to said location, is locked at said location due to a vacuum produced within said bore between the closed distal end of said bore and said piston of said plunger, and also due to the engagement of said elastic portions of said plunger with said un-chamfered portions at the proximal end of said bore in said barrel.

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