Patent ID: 8881562

Claim:
A mortise lock mountable on a door panel, comprising: a latch unit having a key lock hole; an exterior cover having a base plate portion, an aperture formed in said base plate portion in alignment with said key lock hole, a mounting post projecting inwardly from an inner surface of said base plate portion, a peripheral wall projecting inwardly and laterally from said base plate portion and surrounding said aperture and said mounting post; a key lock disposed in said aperture and said key lock hole, said key lock being interlocked with said key lock hole and having an outer periphery that is formed with a first engaging part; a torsional returning unit and a securing plate, said exterior cover further having a pair of internally threaded securing post, said torsional returning unit being mounted on said securing posts and disposed between said exterior cover and said securing plate, said securing plate having securing post holes each of which is disposed around one of said securing posts; and a reinforcing plate mounted on said mounting post and disposed around said key lock, said reinforcing plate including a mounting post hole disposed around said mounting post, a notch that receives said key lock, and a second engaging part disposed in proximity to said notch to engage said first engaging part, said reinforcing plate abutting against said base plate portion and having a lateral flange that projects inwardly away from said base plate portion and that has an inner end substantially flush with an inner end of said peripheral wall of said exterior cover, said lateral flange being adapted to abut against the door panel.