Patent Abstract:
A mortise lock is provided with a reinforcing plate to enhance structural rigidity and robustness for resistance against external destructive pulling forces. The reinforcing plate is disposed in abutment with an exterior cover and a door panel, and is mounted on a mounting post of the exterior cover. The reinforcing plate has a notch to receive and engage a key lock. A securing plate may be disposed between and in abutment with the door panel and a main body of a torsional returning unit which is connected to an exterior handle to further increase structural rigidity.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Patent Application No 100211994 filed on Jun. 30, 2011 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a mortise lock, and more particularly to a mortise lock with high resistance against destructive external pulling forces. 
     2. Description of the Related Art 
     A mortise lock typically includes a latch unit that includes a deadbolt and a live bolt and that can be operated through a key lock or an exterior handle at an outside of a door, or through a rotary button or an interior handle at an inside of the door. The key lock is formed with an external screw thread, and the latch unit has a threaded hole to receive the key lock and to engage the external screw thread. For installation in a door panel, the latch unit is disposed in a latch hole disposed within the door panel and opening at a side face of the door panel, and the key lock is inserted into the threaded hole of the latch unit through a lock hole formed in an outer face of the door panel. The exterior handle is attached to an exterior-cover and the exterior cover is attached to, an outside face of the door panel. The interior handle is attached to an interior cover, and the interior cover is disposed on an inside face of the door panel and is connected to the exterior cover. An example of such a mortise lock is disclosed in U.S. Pat. No. 7,152,442. 
     Generally, conventional mortise locks have no interlocking means to interlock the key lock with the exterior cover. Because retention of the key lock is mainly relied on an engagement between the screw thread of the key lock and the threaded hole in the latch unit, there is no sufficient resistance against external pulling forces, and the key lock can be easily removed from the door panel by burglars using destructive forces to violently pull the key lock and to destroy the screw thread thereof for separation of the key lock from the threaded hole of the latch unit. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a mortise lock with high structural strength to resist against destructive external pulling forces. 
     According to one aspect of the present invention, a mortise lock mountable on a door panel, comprises: a latch unit having a key lock hole; an exterior cover having a base plate portion, an aperture formed in the base plate portion in alignment with the key lock hole, amounting post projecting inwardly from an inner surface of the base plate portion, and a peripheral wall that projects inwardly and laterally from the base plate portion to surround the aperture and the mounting post; a key lock that is disposed in the aperture and the key lock hole, that is interlocked with the key lock hole, and that has an outer periphery formed with a first engaging part; and a reinforcing plate mounted on the mounting post and disposed around the key lock. The reinforcing plate includes a notch that receives the key lock, and a second engaging part disposed in proximity to the notch to engage the first engaging part. The reinforcing plate abuts against the base plate portion and has a lateral flange that projects inwardly away from the base plate portion and that has an inner end substantially flush with an inner end of the peripheral wall of the exterior cover. The lateral flange is adapted to abut against the door panel. 
     According to another aspect of the invention, a mortise lock comprises: a latch unit having a key lock hole; an exterior cover having a base plate portion, an aperture formed in the base plate portion in alignment with the key lock hole, a securing post projecting inwardly from an inner surface of the base plate portion, and a peripheral wall projecting inwardly and laterally from the base plate portion and surrounding the aperture and the securing post; a key lock extending through the aperture and interlocked with the key lock hole; a securing plate mounted on the securing post, and having a securing post hole disposed around the securing post, and a transmission rod hole; an exterior handle attached to the exterior cover; a torsional returning unit having a main body that is mounted on the securing post and that is disposed between the exterior cover and the securing plate, and a cam member that projects from the main body to the securing plate; and a transmission rod connected to the exterior handle to actuate the latch unit and extending through the cam member and the transmission rod hole. The securing plate has an outer side engaging the main body and an inner side adapted to engage the door panel. 
     According to still another aspect of the invention, a mortise lock comprises: a latch unit having a key lock hole; an exterior cover having a base plate portion, an aperture formed in the base plate portion in alignment with the key lock hole, a pair of mounting posts and a pair of securing posts, all of which project inwardly from an inner surface of the base plate portion, and a peripheral wall projecting inwardly and laterally from the base plate portion and surrounding the aperture and the mounting and securing posts; a key lock disposed in the aperture and the key lock hole, interlocked with the key lock hole, and having an outer periphery that is formed with a first engaging part; and a reinforcing plate mounted on one of the mounting posts, disposed around the key lock and abutting against the base plate portion. The reinforcing plate includes a notch that receives the key lock, a second engaging part disposed in proximity to the notch to engage the first engaging part, and a lateral flange projecting inwardly away from the base plate portion and having an inner end substantially flush with an inner end of the peripheral wall of the exterior cover. The lateral flange is adapted to abut against the door panel. The mortise lock, further includes an exterior handle attached to the exterior cover; a torsional returning unit that has a main body mounted on the securing posts, and a cam member projecting from the main body; and a transmission rod connected to the exterior handle to actuate the latch unit and extending through the cam member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a perspective view illustrating a preferred embodiment of the mortise lock according to the present invention mounted on a door panel; 
         FIG. 2  is an exploded view of the preferred embodiment; 
         FIG. 3  is an exploded view showing an exterior lock unit of the preferred embodiment; 
         FIG. 4  is a perspective view of a securing plate of the preferred embodiment; and 
         FIG. 5  is a sectional view of the preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 to 5 , a mortise lock according to a preferred embodiment of the present invention is mountable on a door panel  4  and includes a latch unit  1 , an exterior lock unit  2  and an interior lock unit  3 . The exterior lock unit  2 , includes an, exterior cover  21 , a key lock  22 , a reinforcing plate  23 , a securing plate  24 , a torsional returning unit  25 , a transmission rod  26 , and an exterior handle  27 . 
     The door panel  4  has a latch hole  45  formed through a side face of the door panel  4 . A key lock hole  41 , a transmission rod hole  42 , two first installation holes  43 , and four second installation holes  44  are formed through an outer face of the door panel  4 . 
     The latch unit  1  is installed in the latch hole  45  and has a key lock hole  11  with an internal thread  111 . The latch unit  1  has a deadbolt  11  and a live bolt  12 . Since the construction of the latch unit  1  is known and is not detailed hereinafter. 
     The key lock  22  has an outer periphery formed with a threaded portion  222  and two first engaging parts  221 . The first engaging parts  221  are preferably configured as engaging grooves. The threaded portion  222  passes through the key lock hole  41  in the door panel  4  and is engaged with the internal thread  111  of the key lock hole  11  in the latch unit  1 . 
     The exterior cover  21  includes a base plate portion  211  formed with an aperture  219 . Two internally threaded mounting posts  215  and two internally threaded securing posts  216  project inwardly front an inner surface of the base plate portion  211 . A peripheral wall extends inwardly and laterally from the base plate portion  211  and includes two sidewalls  212 , an upper wall  213 , and a lower wall  217 . The peripheral wall surrounds the aperture  214 , the mounting posts  215  and the securing posts  216 . 
     The reinforcing plate  23  has an upper edge  234 , a lower edge  231 , two opposite sides that interconnect the upper edge  234  and the lower edge  231  and that are formed respectively with lateral flanges  232 , a mounting post hole  233  formed between the upper edge  234  and the lower edge  231 , a notch  236  indented upwardly from the lower edge  231 , and two opposite second, engaging parts  235  formed in proximity to the notch  236 . The notch  236  receives the key lock  22 . The second engaging parts  235  are engaging edges that bound the notch  236  and that respectively engage the first engaging parts  221  of the key lock  22 . The mounting post hole  233  is disposed around one of the mounting posts  215  proximate to the upper wall  213 . An outer surface of the reinforcing plate  23  abuts against the base plate portion  211 . The lateral flanges  232  of the reinforcing plate  23  project inwardly away from the base plate portion  211 . The upper edge  234  and the lateral flanges  232  respectively abut against the upper wall  213  and the sidewalls  212  of the exterior cover  21 . The lateral flanges  232  are substantially parallel to the sidewalls  212  and have inner ends that are substantially flush with inner ends of the side walls  212  and that are adapted to abut against the door panel  4 . 
     The torsional returning unit  25  has a four-sided main body  250  that has four sides  253 , a cam member  251  rotatably mounted to the main body  250 , a cam hole  254  formed in the cam member  251 , and four lateral through holes  252  formed around the cam hole  254 . The main body  250  is mounted on the securing posts  216  and is disposed between the exterior cover  21  and the securing plate  24 . Two of the lateral through holes  252  are disposed around the two securing posts  216 , respectively. 
     The exterior handle  27  is attached movably to the exterior cover  21 . 
     The securing plate  24  has two spaced apart clamp parts  241  protruding from the securing plate toward the main body  250 , a transmission rod hole  245  formed between the clamp parts  241 , two spaced apart bosses  243  protruding from the securing plate  24  and arcuated to extend around the transmission rod hole  245 , two spaced apart recesses  247  arcuated to extend around the transmission hole  245  oppositely of the bosses  243 , and stop elements  246  formed within the recesses  247 . The bosses  243  protrude into the transmission rod hole  42  in the door panel  4  so that the inner side of the securing plate  24  is in engagement with the door panel  4 . The cam member  251  is received rotatably in the recesses  247 . Each recess  247  has two angularly spaced apart shoulders which serve as the stop elements  246 . The stop elements  246  function to limit a rotation angle of the cam member  251 . Preferably, the securing plate  24  is a stamped plate that has a bent area to form the bosses  243 , the recesses  247 , and the stop elements  246 . An inner surface of the bent area is protruded inwardly to form the bosses  243 , and an outer surface of the bent area is indented to form the recesses  247 . 
     The main body  250  of the torsional returning unit  25  has two opposite sides  253  respectively abutting against the sidewalls  212  of the exterior cover  21 , and two other opposite sides  233  clamped by the clamp parts  241  of the securing plate  24 . The main body  250  is therefore in engagement with an outer side of the securing plate  24 . 
     The securing plate  24  further has four securing post holes  242 , and a mounting post hole  244 . Two of the securing post holes  242  are disposed around the securing posts  216 , respectively. The mounting post hole  244  is disposed around the mounting post  215  proximate to the lower wall  217 . The transmission rod  26  has one end connected to the exterior handle  27 . The transmission rod  26  is also connected to the cam member  251  and extends through the cam hole  254  of the cam member  251 . The transmission rod  26  is inserted into the latch unit  1  through the transmission rod hole  245  in the securing plate  24  and the transmission rod hole  42  in the door panel  4 . The latch unit  1  can therefore be actuated by the transmission rod  26 . 
     The interior lock unit  3  includes an interior handle  33 , an interior button  32 , an interior cover  31 , a securing plate  34  and a torsional returning unit  35 . The construction of the securing plate  34  and the torsional returning unit  35  is the same as that of the securing plate  24  and the torsional returning unit  25  of the exterior lock unit  2 . Two screws  28  and two screws  29  are used to secure the interior lock unit  2  to, the mounting posts  215  and the securing posts  216 , respectively. 
     In use, the deadbolt  11  may be actuated by operating the key lock  22  at an outside of the door panel  4  or by operating the rotary button  32  at an inside of the door panel  4 . The live bolt  12  may be actuated by operating the exterior handle  27  or the interior handle  33 . 
     With the reinforcing plate  23  which is disposed in abutment with the base plate portion  211  of the exterior cover  21  and which has lateral flanges  232  to abut against the door panel  4 , the mortise lock of the present invention possesses high structural rigidity and robustness. The structural rigidity of the mortise lock is further increased by the securing plate  24  that is mounted on the securing posts  216  in abutment with the torsional returning unit  25  and the door panel  4 . 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.

Technology Classification (CPC): 8