Abstract:
A mortise lock includes a chassis mounted in a mounting hole of a door and an outside handle assembly mounted to a side of the chassis. The outside handle assembly includes an outside spindle having a first end partially received in the chassis and operably connected to at least one bolt of the chassis such that rotation of the outside spindle causes retraction of the bolt. The first end of the outside spindle includes a perimeter groove, forming a fragile portion. An outside handle includes an end securely connected to a second end of the outside spindle to turn therewith. The fragile portion of the outside spindle is broken when an excessive force is applied to the outside handle. Thus, unauthorized opening of the door by forcibly turning the outside handle is prevented. Further, the mortise lock can be easily installed, and the cost of the mortise lock is cut.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a mortise lock. In particular, the present invention relates to a mortise lock including two handles that can be returned to their original horizontal position. 
   2. Description of the Related Art 
     FIG. 1  of the drawings illustrates a conventional mortise lock comprising an inside handle assembly  1 , an outside handle assembly  2 , and a chassis  3  between the inside handle assembly  1  and the outside handle assembly  2 . The chassis  3  is mounted in a mounting hole (not shown) of a door (not shown) and includes a plurality of bolts  31  and a mechanism for operating the bolts  31 . The inside handle assembly  1  includes an inside handle  11  and an inside spindle  12  having an end received in a spindle hub  32   b  of the chassis  3 . The outside handle assembly  2  includes an outside handle  21  and an outside spindle  22  having an end received in another spindle hub (not shown) of the chassis  3  that is aligned with the spindle hub  32   b . When either handle  11 ,  21  is turned, the associated spindle  12 ,  22  and the associated spindle hub of the chassis  3  are turned to retract the bolts  31 . 
   The inside handle assembly  1  further includes an inside spring package  15  mounted around the inside spindle  12  for returning the inside handle  11  to its original position (generally horizontal) when the inside handle  11  is turned and then released. The inside spring package  15  includes a spring seat  151 , a collar  152  having a square hole  155  through which the inside spindle  12  extends, a spring  153  mounted to the spring seat  151 , and a lid  154  for housing the spring  153  and the collar  152 . When the inside handle  11  is turned, the inside spindle  12  and the collar  152  are turned. When the inside handle  11  is released, the inside handle  11  is returned to its original horizontal position under the action of the spring  153 . The inner handle  11  further includes a threaded section  111  on an end thereof to which a sleeve  13  is mounted. The sleeve  13  includes an inner threading  131  for threadedly engaging with a stud  161  projecting from a side of a connecting member  16  that provides a support for two screws  17  that are engaged with two posts  27  of the outer handle assembly  2 . An inside rose  14  is provided to house the inside spring package  15  and associated elements. Similarly, the outside handle assembly  2  further includes an outside spring package  25 , a sleeve  23 , a connecting member (not shown), and an outside rose  24  for returning the outside handle  21  to its horizontal position. 
   Installation of the sleeves  13 ,  23  to the end of the associated handles  11 ,  21  is troublesome. Further, the sleeves  13 ,  23  may be undesiredly turned together with the handles  11 ,  21  due to friction, causing loosening of the handles  11 ,  21 . Further, the elements of the lock are apt to be damaged or permanently deformed by the torque applied to the handles  11 ,  21  (especially lever-type handles), adversely affecting retraction of the bolts  31 . 
   Further, the handles  11 ,  21  are generally made from brass, which is relatively expensive. Processing of the threaded section  111  of the handles  11 ,  21  and the inner threading  131  of the sleeves  13 ,  23  is troublesome and expensive. Further, special tools are required for mounting the sleeves  13  and  23 . 
   SUMMARY OF THE INVENTION 
   In accordance with a first aspect of the present invention, a mortise lock comprises a chassis mounted in a mounting hole of a door and an outside handle assembly mounted to a side of the chassis. The outside handle assembly includes an outside spindle having a first end partially received in the chassis and operably connected to at least one bolt of the chassis such that rotation of the outside spindle causes retraction of the bolt. The first end of the outside spindle includes a perimeter groove, forming a fragile portion. An outside handle includes an end securely connected to a second end of the outside spindle to turn therewith. The fragile portion of the outside spindle is broken when an excessive force is applied to the outside handle. Thus, unauthorized opening of the door by forcibly turning the outside handle is prevented. Also, damage to the inner mechanism of the mortise lock is prevented. 
   In an embodiment of the invention, the mortise lock further comprises an outside sleeve including a first end securely mounted around a portion of the first end of the outside spindle to turn therewith. A second end of the outside sleeve receives the second end of the outside spindle and is securely connected to the end of the outside handle. The end of the outside handle includes an engaging hole. The outside sleeve includes a longitudinal hole and a longitudinal groove defined in an outer periphery thereof. The outside sleeve further includes a positioning hole and a slot in the outer periphery of the outside sleeve. The slot is communicated with the longitudinal hole and aligned with the engaging hole of the outside handle. 
   A tenon is mounted in the outside sleeve and includes a first end received in the slot of the outside sleeve and a second end having a notch. The tenon further includes an opening. A substantially U-shaped resilient member is mounted in the outside sleeve and includes a first L-shaped leg pressing against an end edge delimiting the opening of the tenon and a second L-shaped leg extending through the notch of the tenon into the positioning hole of the outside sleeve. The resilient member biases the first end of the tenon into the engaging hole of the outside handle. 
   The second end of the outside spindle has an inclined surface pressing against an edge delimiting the opening of the tenon. When the outside spindle is pushed outward, the first end of the tenon is disengaged from the engaging hole of the outside handle, allowing removal of the outside handle from the outside sleeve. 
   Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a conventional mortise lock. 
       FIG. 2  is an exploded perspective view of a mortise lock in accordance with the present invention. 
       FIG. 3  is a side view, partly sectioned, of the mortise lock in accordance with the present invention and a door. 
       FIG. 4  is a sectional view similar to  FIG. 3 , wherein the handles of the mortise lock are turned. 
       FIG. 5  is an exploded perspective view of an outside handle assembly of the mortise lock in accordance with the present invention. 
       FIG. 6  is a perspective view of an inside handle assembly of the mortise lock in accordance with the present invention. 
       FIG. 7  is a sectional view taken along plane  7 — 7  in  FIG. 3 . 
       FIG. 8  is a view similar to  FIG. 7 , wherein an outside handle of the mortise lock is turned. 
       FIG. 9  is a view illustrating turning of an inside handle of the mortise lock in accordance with the present invention. 
       FIG. 10  is a view illustrating disengagement of the outside handle of the mortise lock in accordance with the present invention. 
       FIG. 11  is a view similar to  FIG. 10 , illustrating movement of a tenon of the outside handle assembly. 
       FIG. 12  is an exploded perspective view illustrating detachment of two posts and remounting of the posts and the outside handle. 
       FIG. 13  is a sectional view similar to  FIG. 3 , illustrating use of the mortise lock in accordance with the present invention with an oppositely handed door. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 2 , a mortise lock in accordance with the present invention comprises an inside handle assembly  4 , an outside handle assembly  5 , and a chassis  3  between the inside handle assembly  4  and the outside handle assembly  5 . The chassis  3  is mounted in a mounting hole  61  of a door  6  (e.g., a right handed door) and includes a plurality of bolts (see bolts  31  in  FIG. 1 ), a mechanism for operating the bolts, and two spindle hubs  32   a  and  32   b , which are conventional and thus not described in detail. 
   The inside handle assembly  4  includes an inside spindle  42  having an end received in the spindle hub  32   b  of the chassis  3  and an inside handle  41  connected to the inside spindle  42  to turn therewith. The outside handle assembly  5  includes an outside spindle  52  having an end received in the spindle hub  32   a  of the chassis  3  and an outside handle  51  connected to the outside spindle  52  to turn therewith. When either handle  41 ,  51  is turned, the associated spindle  42 ,  52  and the associated spindle hub  32   a ,  32   b  of the chassis  3  are turned to retract the bolts. 
   The outside handle  51  includes an end  511  to which an outside sleeve  53  is mounted. The outside sleeve  53  includes a first end  530  and a second end  531 . Two stops  534  extend radially outward from the first end  530  of the outside sleeve  53 . A longitudinal groove  533  is defined in an outer periphery of the outside sleeve  53 . Also defined in the outer periphery of the outside sleeve  53  is an annular groove  535  into which a retainer ring  57  ( FIGS. 3 and 5 ) is mounted. The outside sleeve  53  further includes a slot  532  communicated with a longitudinal hole  536  of the outside sleeve  53  and spaced from the annular groove  535 . The outside sleeve  53  further includes a tenon  543  and a resilient member  542  mounted therein. The tenon  543  includes a first end  544  and a second end in which a notch  545  is defined. As illustrated in  FIG. 3 , the first end  544  of the tenon  543  is extended through the slot  532  of the outside sleeve  53  into an engaging hole  512  in the end  511  of the outside handle  51 , thereby positioning the outside sleeve  53 . Preferably, the first end  544  of the tenon  543  has an inclined face  547  to assist in mounting of the outside handle  51 . The resilient member  542  is substantially U-shaped and has two L-shaped legs  542   a  and  542   b . The L-shaped leg  542   a  presses against an end edge delimiting an opening  546  of the tenon  543 , and the other L-shaped leg  542   b  extends through the notch  545  of the tenon  543  into a positioning hole  537  of the outside sleeve  53 . Thus, the first end  544  of the tenon  543  is biased by the resilient member  542  into the engaging hole  512  of the outside handle  51 . 
   An outside trim  55  is mounted around the first end  530  of the outside sleeve  53  for returning the outside handle  51  to its original position when the outside handle  51  is turned and then released. The outside trim  55  includes a spring seat  56 , a ring  552  received in the spring seat  56 , a spring  553  mounted on a side of the ring  552 , and a lid  551  for closing the spring seat  56 . The spring seat  56  includes a plate  561  with a central hole  562  and a cylindrical wall  563  extending from a periphery of the plate  561 . Two pairs of diametrically disposed through-holes  564  are defined in the plate  561  and a pair of diametrically disposed lugs  565  are formed on a side of the plate  561 . Also formed on the side of the plate  561  is a tab  566  angularly spaced from each lug  565  by 90 degrees. A protrusion  567  is formed on the other side of the plate  561  and located at an inner periphery delimiting the central hole  562 . Preferably, the protrusion  567  is diametrically opposed to the tab  566 . 
   The ring  552  received in the spring seat  56  includes a circular body  550  that is received in a space delimited by the lugs  565  and the tab  566 . A protrusion  554  is formed on an inner periphery delimiting a central hole of the body  550  and engaged in the longitudinal groove  533  of the outside sleeve  53 . Formed on an outer periphery of the body  550  and diametrically opposed to the protrusion  554  is a toothed-like stop  555 . Two diametrically disposed legs  556  and  557  are formed on a side of the body  550  and extend in a direction parallel to a longitudinal direction of the outside spindle  52 . Preferably, the annular positions of the legs  556  and  557  correspond to those of the stop  555  and the protrusion  554 . Preferably, each leg  556 ,  557  has a length the same as that of the cylindrical wall  563  of the spring seat  56 . 
   The lid  551  includes two pairs of diametrically disposed holes  559 . The number of the holes  559  corresponds to that of the through-holes  564  of the spring seat  56 . The outside sleeve  53  extends through a central hole (not labeled) of the lid  551 , the central hole of the ring  552 , and the central hole  562  of the spring seat  56 , as shown in  FIG. 3 . Two posts  59  are extended through a pair of holes  559  of the lid  551  and a pair of through-holes  564  of the spring seat  56  into the chassis  3 , as shown in  FIG. 3 . 
   As illustrated in  FIGS. 4 and 5 , the leg  557  of the ring  552  is in intimate contact with an inner face of the tab  566  of the spring seat  56 . Two ends  558  of the spring  553  received in the ring  552  respectively press against a side of the leg  557  of the ring  552  and the other side of the leg  557  of the ring  552 . The retainer ring  57  is partially received in the annular groove  535  of the outside sleeve  53  and sandwiched between the lid  551  and an outside rose  58 . The outside rose  58  is mounted around the outside sleeve  53  and sandwiched between the lid  551  and an end face of the end  511  of the outside handle  51 , best shown in  FIG. 3 . 
   Referring to  FIGS. 2 ,  3 ,  4 , and  6 , the inside handle  41  includes an end  411  to which an inside sleeve  43  is mounted. The inside sleeve  43  includes a first end  430  and a second end  431 . Two stops  434  extend radially outward from the first end  430  of the inside sleeve  43 . A longitudinal groove  433  is defined in an outer periphery of the inside sleeve  43 . Also defined in the outer periphery of the inside sleeve  43  is an annular groove  435  into which a retainer ring  47  is mounted. The inside sleeve  43  further includes a slot  432  communicated with a longitudinal hole  436  of the inside sleeve  43  and spaced from the annular groove  435 . The inside sleeve  43  further includes a tenon  443  and a resilient member  442  mounted therein. The tenon  443  includes a first end  444  and a second end in which a notch  445  is defined. As illustrated in  FIG. 3 , the first end  444  of the tenon  443  is extended through the slot  432  of the inside sleeve  43  into an engaging hole  412  in the end  411  of the inside handle  41 , thereby positioning the inside sleeve  43 . Preferably, the first end  444  of the tenon  443  has an inclined face  447 . The resilient member  442  is substantially U-shaped and has two L-shaped legs  442   a  and  442   b . The L-shaped leg  442   a  presses against an end edge delimiting an opening  446  of the tenon  443 , and the other L-shaped leg  442   b  extends through the notch  445  of the tenon  443  into a positioning hole  437  of the outside sleeve  430 . Thus, the first end  444  of the tenon  443  is biased by the resilient member  442  into the engaging hole  412  of the inside handle  41 . 
   An inside trim  45  is mounted around the first end  430  of the inside sleeve  43  for returning the outside handle  41  to its original position when the inside handle  41  is turned and then released. The inside trim  45  includes a spring seat  46 , a ring  452  received in the spring seat  46 , a spring  453  mounted on a side of the ring  452 , and a lid  451  for closing the spring seat  46 . The spring seat  46  includes a plate  461  with a central hole  462  and a cylindrical wall  463  extending from a periphery of the plate  461 . Two pairs of diametrically disposed through-holes  464  are defined in the plate  461  and a pair of diametrically disposed lugs  465  are formed on a side of the plate  461 . Also formed on the side of the plate  461  is a tab  466  angularly spaced from each lug  465  by    90   degrees. A protrusion  467  is formed on the other side of the plate  461  and located at an inner periphery delimiting the central hole  462 . Preferably, the protrusion  467  is diametrically opposed to the tab  466 . 
   The ring  452  received in the spring seat  46  includes a circular body  450  that is received in a space delimited by the lugs  465  and the tab  466 . A protrusion  454  is formed on an inner periphery delimiting a central hole of the body  450  and engaged in the longitudinal groove  433  of the outside sleeve  43 . Formed on an outer periphery of the body  450  and diametrically opposed to the protrusion  454  is a toothed-like stop  455 . Two diametrically disposed legs  456  and  457  are formed on a side of the body  450  and extend in a direction parallel to a longitudinal direction of the inside spindle  42 . Preferably, the annular positions of the legs  456  and  457  correspond to those of the stop  455  and the protrusion  454 . Preferably, each leg  456 ,  457  has a length the same as that of the cylindrical wall  463  of the spring seat  46 . 
   The lid  451  includes two pairs of diametrically disposed holes  459 . The number of the holes  459  corresponds to that of the through-holes  464  of the spring seat  46 . The outside sleeve  43  extends through a central hole (not labeled) of the lid  451 , the central hole of the ring  452 , and the central hole  462  of the spring seat  46 , as shown in  FIG. 3 . Two screws  49  are extended through a pair of holes  459  of the lid  451  and a pair of through-holes  464  of the spring seat  46  into screw holes (not labeled) in the posts  59 . 
   The leg  457  of the ring  452  is in intimate contact with an inner face of the tab  466  of the spring seat  46 . Two ends  458  of the spring  453  received in the ring  452  respectively press against a side of the leg  457  of the ring  452  and the other side of the leg  457  of the ring  452 . The retainer ring  47  is partially received in the annular groove  435  of the inside sleeve  43  and sandwiched between the lid  451  and an inside rose  48 . The inside rose  48  is mounted around the inside sleeve  43  and sandwiched between the lid  451  and an end face of the end  411  of the inside handle  41 , best shown in  FIG. 3 . 
   Referring to  FIGS. 7 and 8 , when either handle  41 ,  51  is turned (e.g., the outside handle  51 ), the outside spindle  52  is also turned, with the ring  552  being turned by the outside sleeve  53 . The leg  557  of the ring  552  presses against an end  558  of the spring  553  to store energy for returning the ring  552  and the outside spindle  53 . When the outside handle  51  is turned and then released, the outside handle  51  is returned to its original position under the action of the spring  553 . 
   When the outside handle  51  is turned through an angle sufficient to retract the bolts  31  of the chassis  3 , the stop  555  of the ring  552  is stopped by one of the lugs  565  of the spring seat  56  and one of the stops  534  is moved to a position pressing against and thus stopped by the protrusion  567  of the spring seat  56 , preventing further rotational movement of the outside spindle  52  and the outside handle  51 . Similarly, when the inside handle  41  is turned through an angle sufficient to retract the bolts  31  of the chassis  3 , the stop  455  of the ring  452  is stopped by one of the lugs  465  of the spring seat  46  and one of the stops  434  is moved to a position pressing against and thus stopped by the protrusion  467  of the spring seat  46 , preventing further rotational movement of the inside spindle  42  and the inside handle  41 . Thus, excessive torque resulting from excessive turning of the inside handle  41  or the outside handle  51  is avoided, preventing damage to the elements of the mortise lock. Even if an excessive force is applied to either handle  41 ,  51 , the impact would not be transmitted to the bolt-operating mechanism in the chassis  3 . The life of the mortise lock is prolonged. 
   Installation of the sleeve  43 ,  53  into the associated handle  41 ,  51  is simpler as compared to the conventional mortise lock, as no special tool is required. Troublesome processing of the sleeves  13  and  23  of the conventional mortise lock is avoided. Further, the cost of the handles  41  and  51  can be cut, as they can be made of zinc instead of brass. Further, the cost for processing the inner threading  131  in the sleeve  13 ,  23  and for processing the threading section  111  for the handle  11 ,  21  of the conventional design can be saved. 
   In a case that an excessive force (greater than a threshold force) is applied to the outside handle  51  for the purpose of destroying the mortise lock, the resultant torque would be large enough to cause breakage of the outside spindle  52  at the fragile portion  521 . Thus, unauthorized opening of the door by forcibly turning the outside handle  51  is prevented. Also, damage to the inner mechanism of the mortise lock is prevented. 
   The mortise lock in accordance with the present invention illustrated in  FIGS. 1 through 9  is used on, e.g., a right-handed door. Nevertheless, the mortise lock in accordance with the present invention can also be used on a left-handed door. 
   In a case that the installer found that the handles  41  and  51  were installed in the wrong handing, this mistake can be simply solved. Referring to  FIG. 10 , the inside handle assembly  4  is firstly detached, and the outside handle  51  can be detached by pushing the outside spindle  52  outward for the purposes of changing the handing of the inside spindle  42  and the outside spindle  52  to match the orientation of the door (i.e., a left-handed one or a right-handed one), which is convenient to the installer. In particular, when the outside spindle  52  is pushed outward, the inclined surface  523  of the outside spindle  52  presses against and slides across an end edge delimiting the opening  546  of the tenon  543 , causing the first end  544  of the tenon  543  to disengage from the engaging hole  512  of the outside handle  51  and compressing the resilient member  542 . The outside handle  51  can be removed (see  FIG. 11 ) and the outside rose  58  and the outside trim  55  can be then removed. When the force pushing the outside spindle  52  outward is turned and then, the outside spindle  52  is returned to its original position shown in  FIG. 11  under the action of a spring  50  mounted around the reduced second end  522  of the outside spindle  52 . An end of the spring  50  abuts against the tenon  543 , and the other end of the spring  50  abuts against the first end  520  of the outside spindle  52 . The first end  544  of the tenon  543  is moved to a position beyond the slot  532  of the outside sleeve  53  under the action of the resilient member  542 . 
   Referring to  FIG. 12 , the posts  59  are detached from the pair of holes  559  of the lid  551  to allow removal of the outside trim  55 . Referring to  FIG. 13 , the outside handle assembly  5  and the outside trim  55  are mounted to the other side of the door  6 , and the inside handle assembly  4  and the inside trim  45  are mounted to the other side of the door  6 , with the posts  59  being extended through the other pair of holes  559  of the lid  551  (see  FIG. 12 ). The inclined face  547  of the tenon  543  and the inclined face  447  of the tenon  443  assist in mounting of the handles  41  and  51 . Thus, the mortise lock in accordance with the present invention can be used with both left-handed doors and right-handle doors (compare  FIG. 13  with  FIG. 3 ) by easy adjustment of the mortise lock. 
   Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.