Patent ID: 8505345

Claim:
A door lock assembly comprising: an inner disc adapted to be fixed to a door; an inner handle; a single piece inner drive tube inserted into said inner handle and engaging said inner handle for simultaneous rotation therewith, said inner drive tube extending into said inner disc, and having an outer surface in direct contact with said inner handle; an inner rotary plate engaging said inner drive tube, and having a central hole; an outer handle; an outer drive tube connected to said outer handle; a latch-operating tube adapted to operate a latch and engaging and passing through said central hole so that rotation of said inner handle can be transmitted to said latch-operating tube through said inner drive tube and said inner rotary plate; a press button disposed within said inner drive tube and said inner handle; a press button rod extending into said inner drive tube and having one end portion connected to said press button, said press button rod extending through said latch-operating tube and into said outer drive tube; and a cam mechanism associated with said press button and said inner drive tube to cause said press button rod to rotate when said press button is pressed axially, said cam mechanism including an inclined cam groove/slot which is formed in said inner drive tube and which extends substantially in a helical direction, and a cam protrusion formed on said press button and extending into said cam groove/slot so that when said press button is pressed axially, the cam protrusion is always located within the cam groove/slot, wherein said press button includes a first tubular section and a second tubular section, the cam protrusion is formed in said first tubular section of said press button.