Hinge mechanism

A hinge mechanism for separably and pivotably interconnecting a base member with a cover member, said base member having a generally planar hinge wall portion terminated by a straight edge portion, said cover member having a generally planar hinge wall portion terminated by a straight edge portion, the base member hinge wall portion and the cover member hinge wall portion being generally co-planar with the base member straight edge portion and the cover member straight edge portion being closely adjacent each other when the cover member is in an overlying (closed) position relative to the base member, the hinge mechanism comprising:

• a first hinge body secured to said base member hinge wall portion, said first hinge body having a generally cylindrical cavity defining a longitudinal axis and extending into said first hinge body from a first side thereof, said longitudinal axis being parallel to said base member straight edge portion and defining a pivot axis for said hinge mechanism;
• a second hinge body secured to said cover member hinge wall portion;
• a pivot pin having a longitudinal axis parallel to said cover member straight edge portion, said pivot pin being secured to said second hinge body and adapted to be received within said first hinge body cavity with clearance to allow said pivot pin to rotate about said pivot axis;
• said base member hinge wall portion being formed with a blocking wall parallel to and spaced from said first hinge body first side, said blocking wall and said first hinge body first side being planar and orthogonal to said pivot axis, the distance between said first hinge body first side and said blocking wall being greater than the length of said second hinge body and less than the length of said second hinge body together with the length of said pivot pin so that said second hinge body can rotate in the space between said first hinge body and said blocking wall when said pivot pin is received within said first hinge body cavity;
• said blocking wall and a cross section of said second hinge body orthogonal to said pivot pin axis being so shaped that said blocking wall interferes with said second hinge body to prevent removal or insertion of said pivot pin from or into said first hinge body cavity except when said cover member is in a predetermined angular orientation about said pivot axis relative to said base member, said predetermined angular orientation corresponding to an engaging/disengaging position of said cover member;
• said cover member hinge wall portion is formed with a cantilevered beam within the plane of said cover member hinge wall portion and extending toward said pivot pin so that said beam is positioned adjacent said first hinge body when said pivot pin is received within said first hinge body cavity;
• and
• the cross section of said first hinge body orthogonal to said pivot axis is shaped so that:
• (a) when said cover member is in said closed position substantially no lateral force is applied to said beam by said first hinge body;
• (b) as said cover member is moved between said closed position and said normal open position a first predetermined lateral force is applied to said beam by said first hinge body;
• (c) when said cover member is in said normal open position substantially no lateral force is applied to said beam by said first hinge body;
• (d) as said cover member is moved between said normal open position and said engaging/disengaging position a second predetermined lateral force is applied to said beam by said first hinge body;
• and
• (e) when said cover member is in said engaging/disengaging position substantially no lateral force is applied to said beam by said first hinge body.