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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to an unlocking device for a lever handle door lock. More particularly, the present invention is related to the unlocking device to separately actuate the lever handle door lock in locking state by turning an inner lever. 
     2. Description of the Related Art 
     Referring initially to FIG. 13, a conventional tubular lock includes an inner knob  91  and a locking button  911  thereof for locking. The tubular lock further includes an outer knob  92  and a lock core  962 , which are used to rotate an actuating rod  93  and thus to push a shaft  94  and a limiting plate  95 . The actuating rod  93  bears at least one protrusion  931  which engages with an inclined surface  941  of the shaft  94  so as to move the protrusion  931  along the inclined surface  941 . The limiting plate  95  provides with at least one tooth  951 . Moving in an axial direction, the limiting plate  95  causes an engagement/disengagement of the tooth  951  with/from a groove  961  of a rose escutcheon  96  for locking/unlocking purpose. In the locking state, an outer knob  92  is unable to turn a spindle  97  to operate a latch bolt unit (not shown). In the unlocking operation, turning the lock core  962  by a correct key results in a release of the tooth  951  from the groove  961  to allow returning the actuating rod  93 , or turning the inner knob  91  results in a turning movement of the shaft  94 . When the protrusion  931  of the actuating rod  93  stops at a bottom of the inclined surface  941  of the shaft  94 , the limiting plate  95  releases from the rose escutcheon  96  for unlocking purpose. In use, the shaft  94  connects to an auxiliary lock (not shown) to operate for locking or unlocking it. In the unlocking state, turning the outer knob  92  is able to rotate the spindle  97  and the shaft  94  that result in an unlocking drive of the auxiliary lock. Hence, there is a need for an outer lever for a tubular lock assembly or a lever handle door lock which can avoid an outer lever driving an auxiliary lock. 
     The present invention intends to provide an unlocking device for a lever handle door lock, which can avoid an outer lever, in the unlocking state, driving an inner actuating rod to rotate in such a way to mitigate and overcome the above problem. 
     SUMMARY OF THE INVENTION 
     The primary objective of this invention is to provide an unlocking device for a lever handle door lock, which can avoid an outer lever, in the unlocking state, driving an inner actuating rod to rotate that can prevent the outer lever inadvertently unlocking an auxiliary lock. 
     The secondary objective of this invention is to provide the unlocking device for the lever handle door lock, which consists of an inner actuating rod and an outer actuating rod separately driven by an inner lever and an outer lever. 
     The unlocking device for the lever handle door lock in accordance with the present invention includes an inner lever, an outer lever, an inner mounting plate, an outer mounting plate, a spindle, an inner actuating rod and an outer actuating rod. The inner mounting plate and the outer mounting plate mount the inner lever and the outer lever on a door. Each of the inner lever and the outer lever has an assembling hole so that the inner lever and the outer lever are correspondingly connected to the inner actuating rod and the outer actuating rod for separately operating a latch bolt unit. The inner actuating rod is axially aligned with the outer actuating rod and has an end capable of disengaging from that of the outer actuating rod so as to avoid the outer lever driving the inner actuating rod. 
     Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described in detail with reference to the accompanying drawings herein: 
     FIG. 1 is an exploded perspective view of an unlocking device for a lever handle door lock in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is an exploded perspective view of the unlocking device in accordance with the preferred embodiment of the present invention for the lever handle door lock of FIG. 1; 
     FIG. 3 is a partial cross-sectional view of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 4 is a partial cross-sectional view, taken along line  4 — 4  in FIG. 3, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 5 is a partial cross-sectional view, taken along line  5 — 5  in FIG. 3, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 6 is a partially cross-sectional view, similar to that of FIG. 3, of the unlocking device for the lever handle door lock, in locking state, in accordance with the preferred embodiment of the present invention; 
     FIG. 7 is a partial cross-sectional view, taken along line  7 — 7  in FIG. 6, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 8 is a partial cross-sectional view, taken along line  8 — 8  in FIG. 6, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 9 is a cross-sectional view, similar to that of FIG. 8, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention when operated to unlock; 
     FIG. 10 is a partial cross-sectional view of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention when assembled with an auxiliary lock; 
     FIG. 11 is a cross-sectional view, taken along line  11 — 11  in FIG. 10, of the unlocking device for the lever handle door lock in accordance with the preferred embodiment of the present invention; 
     FIG. 12 is a partial cross-sectional view, similar to that of FIG. 10, of the unlocking device for the lever handle door lock, in locking state, in accordance with the preferred embodiment of the present invention; and 
     FIG. 13 is an exploded perspective view of a tubular lock assembly in accordance with the prior art. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 through 3, a lever handle door lock having an unlocking device in accordance with a preferred embodiment of the present invention includes an inner lever mechanism  1 , an outer lever mechanism  2 , a latch bolt unit  3  and a latch bolt actuating unit  4 . 
     Construction of the inner lever mechanism  1  shall be described in detail, referring again to FIGS. 1 and 3. The inner lever mechanism  1  is installed in an interior and fixed on a bored hole of a door by a mounting plate  14 . The mounting plate  14  is combined with a rose escutcheon  10  to which an inner lever  11  is pivotally connected. The inner lever mechanism  1  provides with a returning spring  15  for returning the inner lever  11 . Furthermore, the inner lever mechanism  1  includes a locking button  12  and a non-circular assembling hole  13 . To accomplish the assembling purpose, the non-circular assembling hole  13  allows connection of the inner lever mechanism  1  with the latch bolt actuating unit  4 , and operation of the inner lever  11  to turn the latch bolt actuating unit  4 . 
     Construction of the outer lever mechanism  2  shall be described in detail, referring again to FIGS. 1 and 3. The outer lever mechanism  2  is installed on an outside and fixed on a bored hole of a door by a mounting plate  21 . The mounting plate  21  is combined with a rose escutcheon  22  to which an outer lever  23  is pivotally connected. The rose escutcheon  22  is formed with a pair of nuts  221  adapted to screw-connect with screw members of the inner lever mechanism  1 , and an axial hole  222  adapted to accommodate a lock core  231  which allows a correct key  24  to actuate the latch bolt actuating unit  4 . The rose escutcheon  22  is further formed with a pair of locking recessions  223 . The outer lever mechanism  2  provides with an axial tube  232  and a pair of longitudinal grooves  233  thereof to combine with a returning member  25  and a returning spring  26  thereof. When the turned outer lever  23  is released, the returning member  25  and the returning spring  26  returns the outer lever  23  to an original position. 
     Construction of the latch bolt unit  3  shall be described in detail, referring again to FIGS. 1 and 3. The latch bolt actuating unit  4  is able to operate the latch bolt unit  3 . The latch bolt unit  3  has a pair of cams  31  located at either side adjacent to the inner lever mechanism  1  or the outer lever mechanism  2 . The latch bolt unit  3  includes a latch bolt  32  which can be retracted by turning the cams  31 . 
     Construction of the latch bolt actuating unit  4  shall be described in detail, referring back to FIGS. 1 and 2. The latch bolt actuating unit  4  includes a first actuating rod  41 , a second actuating rod  42 , an actuating stick  43 , a limiting plate  44 , a reinforcing plate  45 , a first elastic member  46  and a second elastic member  47 . 
     The first actuating rod  41  has a first end inserted into the non-circular assembling hole  13  of the inner lever mechanism  1 , and provided with a guiding groove  411 . Alternatively, the first actuating rod  41  has a second end combined with one of the cams  31  of the latch bolt unit  3 , and provided with an engaging protrusion  412 . The first actuating rod  41  is a hollow tube  413  to allow passage of the actuating stick  43 . 
     The second actuating rod  42  has a first end combined with the other of the cams  31  of the latch bolt unit  3 , and provided with an engaging groove  421  for engaging/disengaging with/from the engaging protrusion  412  of the first actuating rod  41 . Alternatively, the second actuating rod  42  has a second end provided with a control cylinder on which formed with a pair of notches  422 . As best shown in FIG. 2, the second end of the second actuating rod  42  provides with a pair of gaps  423  on its end surface  426 . Each of the gaps  423  consists of an inclined surface  424  and a vertical surface  425 . Referring back to FIG. 1, to accomplish correct alignment with an axis, the control cylinder of the second actuating rod  42  is connected to an axial hole  251  of the returning member  25  and rotated therewith. 
     The actuating stick  43  extends successively through the first actuating rod  41  and the second actuating rod  42 , and has a first end connected with the locking button  12  of the inner lever mechanism  1  so that the locking button  12  is able to turn the actuating stick  43 . The actuating stick  43  further has a second end combined with the lock core  231  of the outer lever mechanism  2  so that the correct key  24  is able to turn the actuating stick  43  via the lock core  231 . The actuating stick  43  provides with a guiding rod  431  to confine itself within angular length of the guiding groove  411  of the first actuating rod  41 , and a pair of lugs  432  to engage with the gaps  423  of the second actuating rod  42 . Since the guiding rod  431  is confined within the guiding groove  411 , it constitutes a combination of the first actuating rod  41  and the actuating stick  43 . In operation, each of the lugs  432  of the actuating stick  43  passes through the inclined surface  424  of the second actuating rod  42  and thus stops at the end surface  426  so that a longitudinal movement between the second actuating rod  42  and the combination of the first actuating rod  41  and the actuating stick  43  is allowed. The first actuating rod  41  is engaged/disengaged with/from the second actuating rod  42  due to the longitudinal movement of the second actuating rod  42 . The second end of the actuating stick  43  is further inserted into the limiting plate  44  and the reinforcing plate  45  successively, and a positioning bar  433  is used to prevent releasing the limiting plate  44  and the reinforcing plate  45  from the actuating stick  43 . 
     The limiting plate  44  connected to the second end of the actuating stick  43  has a pair of arms  441 , a plurality of stops  442 , an axial hole  443  and a pair of longitudinal legs  444 . The arms  441  are engaged/disengaged with/from recessions  252  of the returning member  25  or the locking recessions  223  of the rose escutcheon  22 . The axial hole  443  allows passage and rotational movement of the actuating stick  43  while the stops  442  accommodate the lugs  432  of the actuating stick  43  to thereby limit the rotational movement of the actuating stick  43 . The longitudinal legs  444  are received in the notches  422  of the second actuating rod  42  to constitute a combination of the second actuating rod  42  and the limiting plate  44 . 
     The reinforcing plate  45  is connected to the second end of the actuating stick  43  and limited by the positioning bar  433 . The reinforcing plate  45  has a pair of arms  451  and an axial hole  452 . The arms  451  are engaged/disengaged with/from recessions  252  of the returning member  25  or the locking recessions  223  of the rose escutcheon  22 . The axial hole  452  allows passage and rotational movement of the actuating stick  43 . 
     Turning now to FIG. 3, the first elastic member  46  and the second elastic member  47  are coaxial and nested in the axial tube  232  of the outer lever mechanism  2 . The first elastic member  46  biases the positioning bar  433  of the actuating stick  43  so that the engaging protrusion  412  of the first actuating rod  41  is able to elastically engage/disengage with/from the engaging groove  421  of the second actuating rod  42 . The second elastic member  47  biases the reinforcing plate  45  so that the arms  441  of the limiting plate  44  and the arms  451  of the reinforcing plate  45  bias to disengage from the locking recessions  233  of the rose escutcheon  22 . 
     Referring to FIGS. 2 through 5, in the unlocking state, the first elastic member  46  biases the positioning bar  433  of the actuating stick  43  for disengaging and separating the engaging protrusion  412  of the first actuating rod  41  from the engaging groove  421  of the second actuating rod  42 . Then, the lugs  432  of the actuating stick  43  are located in the gaps  423  of the second actuating rod  42 . Meanwhile, the arms  441  of the limiting plate  44  and the arms  451  of the reinforcing plate  45  disengage from the locking recessions  223  of the rose escutcheon  22  due to the biasing force of the second elastic member  47 . Under these conditions the inner lever  11  is able to turn the first actuating rod  41  and the cam  31  of the latch bolt unit  3  for retracting the dead bolt  32 . Alternatively, the outer lever  23  is able to turn the second actuating rod  42  and the cam  31  of the latch bolt unit  3  for retracting the dead bolt  32 . To this end, the longitudinal groove  233  of the axial tube  232  combines with the arm  441  of the combination of the limiting plate  44  and the second actuating rod  42 . 
     Turning now to FIGS. 6 through 8, in the locking state, when the actuating stick  43  is turned 90 degrees and stopped in a vertical direction, the lugs  432  are released from the gaps  423  of the second actuating rod  42 . The lugs  432  had been passed the inclined surfaces  424 , stopped at the end surface  426  and located between the second actuating rod  42  and the limiting plate  44 , as best shown in FIG.  6 . The actuating stick  43  and the first actuating rod  41  move together an axial distance toward the outer lever mechanism  2  so that the engaging protrusion  412  of the first actuating rod  41  is engaged with the engaging groove  421  of the second actuating rod  42 . Meanwhile, the axial movement of the actuating stick  43  overcomes the biasing force of the elastic members  46  and  47 , thereby the arms  441  of the limiting plate  44  and the arms  451  of the reinforcing plate  45  commonly engaging with the locking recessions  223  of the rose escutcheon  22 . As best shown in FIGS. 7 and 8, turning the outer lever  23  is not allowed since the arms  441  of the limiting plate  44  and the arms  451  of the reinforcing plate  45  are commonly engaged with the locking recessions  223  of the rose escutcheon  22 . Thereby, the latch bolt actuating unit  4  is locked. 
     Turning now to FIG. 9, there is a need for a correct key for turning the lock core  231  and unlocking the latch bolt actuating unit  4  since the outer lever  23  is not allowed to turn. Alternatively, users can turn the inner lever  11  to unlock the latch bolt actuating unit  4  that the first actuating rod  41  and the second actuating rod  42  are commonly turned by the inner lever  11 . The actuating stick  43  is also turned a predetermined angle and consequently stopped in a horizontal direction. When the inner lever  11  returns to the original position, the first actuating rod  41  and the second actuating rod  42  are commonly returned. Initially, the lugs  432  of the actuating stick  43  are confined by the stops  442  of the limiting plate  44 . The longitudinal legs  444  are aligned and combined with the notches  422  of the second actuating rod  42  until the second actuating rod  42  is turned a predetermined angle. Synchronously, the lugs  432  of the actuating stick  43  run on the inclined surface  424  of the second actuating rod  42  and slide into the gaps  423  of the second actuating rod  42  due to the biasing force of the first elastic member  46 . Then the actuating stick  43  has an axial movement toward the inner lever mechanism  1 . Consequently, the engaging protrusion  412  of the first actuating rod  41  is disengaged from the engaging groove  421  of the second actuating rod  42 . Meanwhile, the arms  441  of the limiting plate  44  and the arms  451  of the reinforcing plate  45  are commonly disengaged from the locking recessions  223  of the rose escutcheon  22  by the biasing force of the second elastic member  47 . Thereby, the latch bolt actuating unit  4  is returned to unlock. 
     Turning now to FIGS. 10 and 11, the lever handle door lock is assembled with a combination of an auxiliary lock  5  and a connecting mechanism  6 . The inner lever mechanism  1  further includes a pressing plate  16  and an assembling hole  161  thereof. The first actuating rod  41  is extended through the assembling hole  161  of the pressing plate  16  to combine therewith. The connecting mechanism  6  includes a connecting plate  61  having a first end connecting with the auxiliary lock  5 , and a second end connecting with the inner lever  11  of the inner lever mechanism  1  via the pressing plate  16 . Turning the pressing plate  16  may pull the connecting plate  61  down and thus it may result in rotation of an actuating cam  62 . The auxiliary lock  5  includes an actuating stick  51  extended through the actuating cam  62  and combined therewith. When the connecting plate  61  rotates the actuating stick  51  and the actuating cam  62 , a dead bolt  52  of the auxiliary lock  5  is retracted. 
     Referring back to FIG. 10, in the unlocking state, the first actuating rod  41  is disengaged and separated from the second actuating rod  42 . Thus the inner lever  11  is able to synchronously retract the dead bolt  32  of the latch bolt unit  3  and the dead bolt  52  of the auxiliary lock  5  by turning the first actuating rod  41 . When the auxiliary lock  5  is locked and the lever handle door lock is still maintained in the unlocking state, the outer lever  23  can turn the second actuating rod  42  but cannot turn the first actuating rod  41  which is disengaged from the second actuating rod  42 . Under these conditions, the outer lever  23  is only permitted to retract the dead bolt  32  of the latch bolt unit  3  by turning the second actuating rod  42 , and is not permitted to retract the dead bolt  52  of the auxiliary lock  5 . Consequently, the outer lever  23  can avoid unlocking the auxiliary lock  5  by accident and increase the security in use. 
     Turning now to FIG. 12, in the locking state, turning the locking button  12  or locking the lock core  231  can drive rotation of the actuating stick  43  to lock lever handle door lock. In the unlocking operation, turning the inner lever  11  can commonly turn the first actuating rod  41  and the second actuating rod  42  engaged therewith. Subsequently, the rotation of the first actuating rod  41  can retract the dead bolt  32  of the latch bolt unit  3  and the dead bolt  52  of the auxiliary lock  5 . Meanwhile, the rotation of the second actuating rod  42  can permit turning the outer lever  23  to unlock the lever handle door lock. 
     The unlocking device for the lever handle door lock in accordance with the present invention carries out to synchronously unlock the lever handle door lock and the auxiliary lock in the locking state by turning the inner lever. In the unlocking state, turning the outer lever can avoid unlocking the auxiliary lock by accident. 
     Although the invention has been described in detail with reference to its presently preferred embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.

Summary:
An unlocking device for the lever handle door lock includes an inner lever, an outer lever, an inner mounting plate, an outer mounting plate, a spindle, an inner actuating rod and an outer actuating rod. The inner mounting plate and the outer mounting plate mount the inner lever and the outer lever. Each of the inner lever and the outer lever has an assembling hole so that the inner lever and the outer lever are correspondingly connected to the inner actuating rod and the outer actuating rod for separately operating a latch bolt unit. The inner actuating rod has an end capable of disengaging from that of the outer actuating rod so as to avoid driving the inner actuating rod.