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Non-reusable safety syringe

  • US 5,562,624 A
  • Filed: 05/11/1994
  • Issued: 10/08/1996
  • Est. Priority Date: 05/06/1994
  • Status: Expired due to Term
First Claim
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1. Non-reusable safety syringe comprising:

  • a) a cylinder (1) having a front end and a rear end;

    b) a needle (4) which is fixed to a needle-holder (3), which is fitted removably to the front end of the cylinder (1);

    c) a plunger (6) which is slidable in the cylinder (1) from a position of maximum withdrawal for the filling of the syringe to a position of maximum insertion for the discharging of the syringe, and which is provided with a manually movable stem (7) which projects beyond the rear end of the cylinder (1);

    d) a protective sleeve (12) fitted slidably on the outside of the cylinder (1) and so that it can be moved from a withdrawn inoperative position, in which the needle (4) projects beyond the sleeve (12), to a forward safety position, in which the protective sleeve (12) extends entirely around the needle (4), covering the needle (4) completely;

    e) hooked securing teeth (17) which are provided at free rear ends of elastically flexible securing tongues (16) extending longitudinally with respect to the protective sleeve (12), the tongues being formed in one piece with the sleeve (12), while the securing teeth (17) interact with a complementary retaining rim on the rear end of the cylinder (1) to secure the protective sleeve (12) in its withdrawn position with respect to the cylinder (1);

    f) a releasing pusher element (19) which is fixed to a rear end of the stem (7) of the plunger (6) and which interacts with the securing teeth (17) to disengage said teeth from the retaining rim on the rear end of the cylinder (1), substantially in a terminal section of an insertion path of the plunger (6);

    g) a spring (15) which is interposed between the cylinder (1) and the protective sleeve (12) and which is designed to move the protective sleeve (12) from its withdrawn inoperative position to its forward safety position;

    h) two removal prevention teeth (21) which are disposed diametrically opposite each other at the rear end of the cylinder (1) and which can be moved elastically radially outwards away from each other, and can interact with a rear side of the releasing pusher element (19), securing the stem (7) of the plunger (6) in the maximum insertion position of the path of the plunger (6);

    i) removable safety means (34) which are provided at the rear end of the cylinder (1), to prevent the releasing pusher element (19) from interacting with the securing teeth (17); and

    j) securing means which are capable of automatically retaining both the protective sleeve (12) in its forward safety position so that it cannot be withdrawn with respect to the cylinder (1) and the needle-holder (3) so that it cannot be removed axially in either direction from said protective sleeve (12) in its forward safety position, and which consist of at least one internal projection (25) in the protective sleeve (12) for retention at a rear of the needle-holder (3) which interacts with a corresponding external projection (303) on the needle-holder (3) itself, and of at least one elastic front retaining tongue (23) on the needle-holder (3), which is formed by cutting a peripheral wall of the protective sleeve (12) and which extends longitudinally with respect to the sleeve, a front end of said retaining tongue being connected to the protective sleeve (12), while a free rear end of said retaining tongue interacts, in a position of radial entry into the protective sleeve (12), with a corresponding front projection (203) of the needle-holder (3);

    characterized in that the at least one retaining tongue (23) is cut in a front terminal section of the protective sleeve (12) so as to extend initially, in an unstressed condition, substantially coplanar with the peripheral wall of the protective sleeve, while the at least one retaining tongue interacts with an end cap (26) which reduces a front hole (28) for the needle (4) which may be fitted over and secured removably to an end of the protective sleeve (12), so that the tongue (23) is compressed radially inwards in an inclined position with the end of the retaining tongue projecting inside the protective sleeve (12); and

    further characterized in that an external projection (123) interacting with an inner surface of the end cap (26) is provided on an outer side of the retaining tongue (23) to cause a radial inclination of the retaining tongue (23) towards an inside of the sleeve (12) when the end cap (26) is fitted onto the sleeve (12).

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