Child-resistant closure

  • US 5,370,251 A
  • Filed: 07/22/1993
  • Issued: 12/06/1994
  • Est. Priority Date: 07/22/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A child resistant screw-on closure for use on a container having a threaded portion threadedly engageable with said screw-on closure, comprising:

  • an inner cap defining a vertical axis and comprising a top and a cylindrical skirt depending from said top and annularly surrounding said vertical axis, said cylindrical skirt having an outer and an inner surface, the inner surface of said skirt being threaded for threaded engagement with the container when said inner cap is rotated in one direction and is disengageable therefrom when said inner cap is rotated in an opposite direction;

    an outer cap comprising a top and a cylindrical skirt coaxial with and surrounding the skirt of said inner cap, said cylindrical skirt having an outer and inner surface, said inner and outer caps being in close confronting relation and being axially moveable relative to one another;

    the inner surface of said skirt of said outer cap having a plurality of knurlings extending away from the top thereof in an angular direction, extending axially and in said one direction; and

    said skirt of said inner cap having a portion adjacent said top of a given thickness and another portion adjacent said first portion that protrudes radially outwardly from said first portion to define a thicker portion, the radial shoulder between said two portions defining a plurality of triangular saw toothed projections complimentary to said plurality of knurlings, each of said plurality of triangular saw toothed projections further comprising a sloped first surface and a second surface, said sloped first surface sloping at an angle to the vertical axis in the range of about 30°

    to 60°

    , said second surfaces providing an abutment for said knurlings so that when said outer cap is turned in said one direction, said plurality of knurlings and said plurality of triangular saw toothed projections will engage to rotate said inner cap in said one direction to threadedly engage said inner cap on said container, and when said outer cap is rotated in an opposite direction, said plurality of knurlings will be cammed by said plurality of triangular saw toothed projections to disengage said inner and outer caps to prevent the rotation of said inner cap in said opposite direction to open said container, said camming being preventable by applying an axial force to said outer cap toward said inner cap to enable said outer cap to impart rotation to said inner cap in said opposite direction.

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