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Needle covering mechanism, needle holder and hypodermic syringe

  • US 6,817,989 B2
  • Filed: 12/19/2002
  • Issued: 11/16/2004
  • Est. Priority Date: 06/23/2000
  • Status: Expired due to Fees
First Claim
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1. A needle covering mechanism (1, 1

  • ) for a hypodermic syringe (2, 2

    ) comprising a barrel (7, 7

    ) for an injectant and a plunger (31) for expelling the injectant from the barrel (7, 7

    ), the needle covering mechanism (1, 1

    ) comprises a protective cover sleeve (4) which is movable between a retracted position in which a needle (27) is exposed and an extended position in which the needle (27) is covered, a helical compression spring (8) located inside the cover sleeve (4) for biasing the cover sleeve (4) towards the extended position, a lock for keeping the cover sleeve (4) in the retracted position, and a release mechanism for releasing the lock, the needle covering mechanism (1, 1

    ) is characterised by;

    a body (3, 3

    ) with a cover sleeve retraction chamber (10), which body (3, 3

    ) in a first end (5, 5

    ) is adapted to receive injectant from the barrel (7, 7

    ) and in a second end (6) has an opening for the cover sleeve (4), the cover sleeve (4) being slidingly supported inside the body (3, 3

    ), enabling movement of the cover sleeve (4) between the extended position and the retracted position essentially inside the retraction chamber (10), a retainer (9) for the cover sleeve (4), slidingly supported inside the cover sleeve (4), the retainer (9) comprises an external sliding surface (12), a base portion (15) for fixing and supporting the needle (27), an abutting potion (13) for the helical spring (8), a first radially compressible portion (14) with first detents (16) which in a non-compressed position projects radially out from the sliding surface (12) of the retainer (9) and in a compressed position are flush or within the sliding surface (12), a second radially compressible portion (21) with second detents (22) which in a non-compressed position projects radially out from the sliding surface (12) of the retainer (9) and in a compressed position are flush or within the sliding surface (12), a spacer (11) for maintaining the first radially compressible portion (14) of the retainer (9) in the non-compressed position, made from a material which after some time in contact with the injectant loses its mechanical strength, and a trigger (20, 20

    ), slidingly supported inside the body (3, 3

    ), comprising a funnel-shaped portion (18) facing the first radially compressible portion (14) of the retainer (9), wherein, in an operating position of the needle covering mechanism (1, 1

    ),the cover sleeve (4) is located essentially inside the retraction chamber (10) and the compression spring (8) is tensioned and biases the first radially compressible portion (14) of the retainer (9) towards the funnel-shaped portion (18) of the trigger (20, 20

    ), the trigger (20, 20

    ) abuts stoppers (23, 23

    ) fixed relative to the body (3, 3

    ), preventing a movement of the trigger (20, 20

    ) towards the syringe barrel (7, 7

    ), the second detents (22) of the retainer (9) engage indentations (24) fixed relative to the body (3, 3

    ), preventing a movement of the retainer (9) away from the syringe barrel (7, 7

    ), and the first detents (16) of the retainer (9) engage indentations (25) in the cover sleeve (4), preventing a movement of the cover sleeve (4) towards the extended position, whereupon a contact between the spacer (11) and the injectant causes the spacer (11) to lose its mechanical strength and deform, the compression spring (8) forces the first radially compressible portion (14) of the retainer (9) into the funnel-shaped portion (18) of the trigger (20, 20

    ) and thus into the compressed position, the first detents (16) slip out of the indentations (25) in the cover sleeve (4), thereby releasing the cover sleeve (4) from the retracted position, and the spring (8) forces the cover sleeve (4) to the extended position.

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