Abstract:
A combination lock is provided, each of buttons of which has to be pressed respective correct numbers of times (including zero time) for unlocking the lock, therefore there is wider variety of different unlocking combinations with limited numbers of buttons, preventing unauthorized persons from easily guessing the current unlocking combination. The combination lock is made such that a knob connected thereto will be, when operated, only capable of turning in an idle manner without causing a dead bolt to disengage a door equipped with the lock unless all numbered buttons of the lock are correctly pressed according to the current unlocking combination, preventing unauthorized persons from succeeding in unlocking the door by means of turning the knob violently.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a combination lock, more particularly one, which is used on a door, and comprised of several numbered buttons, each having to be pressed correct numbers of times for unlocking the lock, and which is constructed such that a knob connected thereto will be, when operated, only capable of turning in an idle manner without causing a dead bolt to retreat to the disengaged position unless all of the numbered buttons are respectively pressed correct number of times to make the lock unlock.  
           [0003]    2. Brief Description of the Prior Art  
           [0004]    The importance of locks has never been negated since first locks were made available, and many different locks have been made over time, each having a particular usage and function, e.g. gear shift locks, steering wheel locks, steel rope locks, mortise locks, and combination locks. There are more and more large buildings equipped with combinations locks, by means of which the management of the buildings can be sure that only authorized persons have access to the buildings.  
           [0005]    A type of conventional lock is made to have several numbered buttons fitted thereon, and correct ones of the numbered buttons have to be pressed for unlocking the lock. In other words, each of the numbered buttons is either in pressed position or not-pressed position when the buttons are operated according to the unlocking combination to unlock the lock. For a combination lock of such type that has ten numbered buttons, and that can be unlocked by means of pressing four correct ones of the buttons, the chance of successful unlocking is one in one hundred and forty  
         c   4   10     =       10   !         4   !            (     10   -   4     )     !                               
 
           [0006]    in one try to unlock the lock, wherein four randomly chosen ones of the buttons are pressed. Therefore, there is not a wide enough variety of different unlocking combinations for a lock of the above type that is equipped with few buttons, e.g. fewer than ten, to prevent unauthorized persons from easily guessing the current unlocking combination.  
           [0007]    Furthermore, conventional combination locks are made in such a manner that when they are used together with a knob on a door, and when numbered buttons thereof are not correctly pressed according to the unlocking combination, internal stopping parts of the locks will stay engaged with the knob to prevent the knob from turning, thus preventing a dead bolt from disengaging the door. Consequently, a thief will be able to force the lock to unlock by means of turning the knob violently to disengage the dead bolt from the door.  
         SUMMARY OF THE INVENTION  
         [0008]    It is a main object of the present invention to provide a combination lock, which is made in such a manner that there is a wider variety of different unlocking combinations provided to it than conventional combination locks with same numbers of buttons, thus preventing a thief from easily guessing the current unlocking combination; the combination lock is comprised of several numbered buttons, each of which has to be pressed respective correct numbers of times (including zero time) for unlocking the lock.  
           [0009]    It is another object of the present invention to provide a combination lock, which is made such that a knob connected thereto will be, when operated, only capable of turning in an idle manner without causing a dead bolt to disengage the door unless all numbered buttons of the lock are correctly pressed according to the current unlocking combination. In other words, the knob will be engaged with the dead bolt to be operable to disengage the dead bolt from the door only when the combination lock is unlocked, preventing a thief from succeeding in forcing the lock to unlock by means of turning the knob violently. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention will be better understood by referring to the accompanying drawings, wherein:  
         [0011]    [0011]FIG. 1 is an exploded perspective view of the combination lock according to the present invention,  
         [0012]    [0012]FIG. 2 is a first partial exploded perspective view of the combination lock according to the present invention,  
         [0013]    [0013]FIG. 3 is a second partial exploded perspective view of the combination lock according to the present invention,  
         [0014]    [0014]FIG. 4 is a view showing installing of the combination lock to a door according to the present invention,  
         [0015]    [0015]FIG. 5 is a first vertical cross-sectional view of the combination lock according to the present invention,  
         [0016]    [0016]FIG. 6 is a partial view of the combination lock of the present invention,  
         [0017]    [0017]FIG. 7 is a first front view of the combination lock according to the present invention,  
         [0018]    [0018]FIG. 8 is a second front view of the combination lock according to the present invention,  
         [0019]    [0019]FIG. 9 is a top view of the combination lock of the present invention,  
         [0020]    [0020]FIG. 10 is a partial side view of the combination lock of the present invention with numbered buttons in depressed position,  
         [0021]    [0021]FIG. 11 is a view of the ringed lock plates of the combination lock of the present invention under setting of unlocking combination,  
         [0022]    [0022]FIG. 12 is a view showing operation of the unlocking combination setting knob of the combination lock of the present invention,  
         [0023]    [0023]FIG. 13 is view showing the position of the ringed lock plates after the unlocking combination has been set,  
         [0024]    [0024]FIG. 14 is a view showing operation of the confirmation button of the combination lock of the present invention,  
         [0025]    [0025]FIG. 15 is a partial view of the combination lock of the present invention when the knob connected to a door is being operated,  
         [0026]    [0026]FIG. 16 is a section of the combination lock of the present invention after the knob connected to the door has been operated, and  
         [0027]    [0027]FIG. 17 is a section of the combination lock of the present invention when the clear button is being depressed. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring to FIGS. 1, and  2 , a preferred embodiment of a combination lock in the present invention includes an outward housing part  1 , an inner base  2 , a push plate  3 , a main recover base  4 , a bottom base  5 , a bottom cover  6 , and an inward housing part  7 , and is to be fitted to a door  8  for use:  
         [0029]    the outward housing part  1  has a knob mechanism  11  fitted thereto, which is provided for retreating a dead bolt  81  to a disengaged position so that the door is unlocked; the outward housing part  1  has several button holes  12  formed thereon for buttons to be fitted thereto, which buttons includes one clear button  13 , one confirmation button  18 , and numbered buttons  14 ;  
         [0030]    referring to FIG. 3, the knob mechanism  11  includes a knob  111 , an inner member  112 , a fixing base  113 , a rotary gear  114 , and a push base  115 ; the knob  111  has a hollow post  1111  formed with threads on an inner side thereof; the inner member  112  has a middle hole  1121 , and several engaging protrusions  1122  around the middle hole  1121  on an inner annular side; the inner member  112  is arranged in the knob  111  with the threaded hollow post  1111  passing through the middle hole  1121 ; the fixing base  113  has engaging holes  1131  on the edge of an upper end, a middle through hole  1132 , a holding hole  1133  under and in communication with the middle through hole  1132 , and a polygonal engaging hole  1135  under the holding hole  1133 ; the fixing base  113  is joined to the knob  111  with the threaded hollow post  1111  passing through the middle through hole  1132  thereof, with the engaging protrusions  1122  of the inner member  112  fitting in corresponding engaging holes  1131 , with a bolt or screw  1134  being disposed in the holding hole  1133 , and screwed into the threaded hollow post  1111 ; the rotary gear  114  has a polygonal connecting portion  1141  at a lower end, a plate portion  1142  adjacent to the polygonal connecting portion  1141 , slopes  1143  on the lower side of the plate portion  1142 , a polygonal engaging portion  1444  on the upper side of the plate portion  1142 , a cylindrical portion  1145  on top of the polygonal engaging portion  1444 , and a spring  1146  disposed in the cylindrical portion  1145 ; the push base  115  has a polygonal connecting cavity  1151  on a middle of an upper side thereof, two push posts  1152  nearer to the edge; the push base  115  is joined to the rotary gear  114  with the polygonal connecting portion  1141  fitting into the polygonal connecting cavity  1151  thereof, and with the push posts  1152  being capable of pushing the push plate  3 ;  
         [0031]    the confirmation button  18  consists of an actuating rod  181 , and a cap  183 ; the actuating rod  181  has a holding post  1811  at an upper end portion, which is passed through a spring  182 , and the cap  183 ; the actuating rod  181  has a containing hole  1812  on a first side, in which a spring  184 , an engaging pin  185 , and a detaining ring  186  are fitted so that the engaging pin  185  is biased outwardly of the containing hole  1812 ; a holding post  1814  is formed at the bottom of the actuating rod  181 , which is passed through a spring  187 ; the actuating rod  181  further has a slope  1815  formed at an opposite side of the first side to be faced with the pushing slope plate  39  of the push plate  3 ;  
         [0032]    the clear button  13  consists of a lower push post  131 , and a cap  134 ; the push post  131  is formed with a slope  1311 , and is passed through springs  132 , and  133  at upper and lower portions  1312 , and  1313  thereof respectively while the cap  134  is mounted on top of the push post  131 ;  
         [0033]    referring to FIG. 2, each numbered button  14  consists of a cap  142 , a rotary shaft  143 , and an upper piston  141 , which has a top flat portion  1411 , a lower hollow rod  1412 , and a curved bar  1413  adjacent to the lower hollow rod  1412 ; the cap  142  is fitted on the top flat portion  1411 ; the lower hollow rod  1412  is formed with screw threads on an inner side; the rotary shaft  143  has a hole  1431 , a curved protrusion  1432  on the upper end, a recess  1433  opposite the curved protrusion  1432  on the upper end, and several protrusions  1435  on an outward side; a torsion spring  146  is held in the hole  1431  with one end thereof being secured to an engaging trench  1434  in the rotary shaft  143 ; the upper piston  141  is passed into the hole  1431  at the lower hollow rod  1412  thereof with the curved bar  1413  being held in the recess  1433  while a bolt  144  is passed through a fixing plate  145 , a lower end of the hole  1431 , and the torsion spring  146 , and then screwed into the lower hollow rod  1412 ; the other end of the torsion spring  146  is engaged with a gap  1451  formed on the edge of the fixing plate  145 ; the rotary shaft  143  is passed through a spring  147  so that the shaft  143 , and the upper piston  141  connected to the shaft  143  are biased upwards by the spring  147 ;  
         [0034]    a lock plate cover  15  is disposed, according to FIG. 1, under the springs  147 , which is formed with through holes  151  for corresponding numbered buttons  14  to pass through, and gaps  152  adjacent to each through hole  151 ; the gaps  152  are provided for fitting with the protrusions  1435  of the rotary shaft  143 ; ringed lock plates  16 , each of which has a flat portion  161  on an outward side as well as several trenches  162 , are arranged under respective through holes  151  of the lock plate cover  15 ; rotary bases  17  are arranged in respective ringed lock plates  16  with outward bumps  171  thereof fitting in the trenches  162  so that they can turn together with the ringed lock plates  16 ; each rotary base  17  is formed with several equidistantly spaced guide trenches  172 , each of which slopes at an upper portion, and is vertical at a lower end portion; each rotary base  17  is formed with a lower section  173  smaller than an upper section so that the lower section  173  is in the shape of a step; the step-shaped lower section  173  is formed with an engaging hole  174 , of which the edge is substantially similar to a track; each rotary base  17  is further formed with equidistantly spaced protrusions  175  on the bottom of the upper bigger section thereof;  
         [0035]    the inner base  2  is formed with several holding rooms  21  thereon, corresponding to the numbered buttons  14  for holding respective ringed lock plates  16  and respective rotary bases  17  therein; the inner base  2  is formed with an annular platform  22  in each holding room  21 , and several equidistantly spaced cavities  221  on each platform  22 ; beads  222  are positioned on the cavities  221 ; slide plates  23  are positioned over respective platforms  22 ; each slide plate  23  has a middle hole  231 , and gaps  232  adjacent to the middle hole  231 , into which protrusions  175  of the rotary bases  17  are fitted; hollows are formed on upper side of the inner base so that lateral sides of the ringed lock plates  16  are allowed to show; stopping protrusions  24  are formed next to lower ends of the holding rooms  21 ; the inner base  2  has two holding holes  25  at a first end, in which lock pins  251 , and springs  252  are fitted, and over which covers  253  are disposed to prevent the lock pins  251  and springs  252  from falling out; each lock pin  251  has a slope  2511 ; a through hole  28  are formed between the holding holes  25 , through which the actuating rod  181  is passed; the inner base  2  has a downwards extended plate  29  at the first end, which is formed with a through hole  291 ; the inner base  2  further has down extended walls at the other end, each of which has a connecting post  26  and a recess  27  formed thereon; springs  37  are passed around respective connecting posts  26  at one end while springs  45  are fitted onto respective recesses  27  at one end;  
         [0036]    the push plate  3  is formed with a middle hole  31 , a corrugated portion adjacent to the middle hole  31  on an inward side thereof, an opening  33 , a pushing protrusion  38  in the opening  33 , two sloping protrusions  34  formed at opposite direction of the pushing protrusion  38 ; the sloping protrusions  34  face respective slopes  2511  of the lock pins  251 ; a pushing slope plate  39  is formed between the sloping protrusions  34 , and two downwards extending pushing plates  35  are formed at two inward sides of the push plate  3  that are adjacent to lateral edges of the opening  33 ; the corrugated portion has several curved recess portions  32 , which face respective ones of the ringed lock plates  16 ; a slot  30  is formed on the push plate  3  next to the opening  33 , and two sloping portions  301  are formed on one of those portions of the push plate  3  that are adjacent to the slot  30 ; the rotary gear  114  are passed through the slot  30  with the slopes  1143  of the plate portion  1142  thereof facing respective ones of the sloping portions  301  of the push plate  3 ; the push plate  3  further has elongated holding protrusions  36 , and the springs  37 , which are passed around connecting posts  26  of the inner base  2  at one end, are passed around the elongated holding protrusions  36  at the other end portions;  
         [0037]    the main recover base  4  is arranged, also according to FIG. 1, under the push plate  3 , and has several elongated holes  41  corresponding to respective numbered buttons  14  in position, two bumps  42  on an upper side of a first end for propping respective lock pins  251  with, and two positioning posts  44  at the other (second) end, which are passed into the other ends of the springs  45  fitted over the recesses  27  of the inner base  2 ; the main recover base  4  is formed with a slope  43  at the other (second) end, corresponding to the slope  1111  of the clear button  13  in position; several equidistantly spaced push protrusions  46 , each which is formed with a slope  461 , are formed along a lower side of the main recover base  4 ; rotary control elements  47  are arranged above respective elongated holes  41 ; each of the rotary control elements  47  has a flat portion  471 , and a polygonal engaging portion  472  on top of the flat portion  471  and fitting into corresponding engaging holes  174  of the rotary bases  17 ; each rotary control element  47  has a polygonal engaging projection  473  on the bottom of the flat portion  471 , a stopping protrusion  474  beside the polygonal engaging projection  473 , and a torsion spring  475  fitted thereto, which engages corresponding stopping protrusions  24 , and  474  at two ends; rotary locating shafts  48  are arranged under the elongated holes  41  of the main recover base  4 ; each rotary locating shaft  48  has an engaging hole  481  at a middle, into which polygonal engaging projection  473  of a corresponding rotary control element  47  is fitted so that each ringed lock plate  16  and corresponding rotary base  17 , rotary control element  47 , and rotary locating shaft  48  will move together with each other; each rotary locating shaft  48  is formed with several engaging trenches  482  on an outward side, each of which engaging trenches  482  includes a flat side  4821 , and a curved side  4822 , such that each rotary locating shaft  48  is prevented from turning back by means of a corresponding locating pin  492  (to be detailed later) after a corresponding numbered button  14  has been pressed one time to make it turn forwards; each rotary locating shaft  48  is formed with a hollow post  483  at a lower end, which has screw threads on an inner side, and has a stopping protrusion  484  near to the threaded hollow post  483 , and has a torsion spring  485  fitted under it with the stopping protrusion  484  being arranged between two ends of the spring  485 ; the elasticity of the springs  485  is greater than that of the springs  475  connected to the rotary control elements  47 ; a recover base  49  is disposed under the main recover base  4 ; the recover base  49  has sloping trenches  494  each corresponding to one of the slopes  461  of the push protrusions  46  in position; the recover base  49  has several pairs of hollows and through holes  491 , facing the rotary locating shafts  48 ; there is a locating pin  492  passed through each through hole  491 , and a spring  493  joined to each locating pin  492  for biasing the locating pin  492  outwardly of the through hole  491 ;  
         [0038]    the bottom base  5  has several through holes  51 , which communicate with each other, for the rotary locating shafts  48  to be passed through; the bottom base  5  has limiting stop posts  52  each next to one of the through holes  51 ; the posts  52  have curved sides facing corresponding through holes  51 ;  
         [0039]    the bottom cover  6  is arranged under the bottom base  5 , and has round holes  61  under corresponding through holes  51  of the bottom base  5 ; holed fixing plates  62  are positioned over the round holes  61 , through which screws  63 , and a screw  64  are passed; a spring base  65  is positioned between the bottom cover  6  and the bottom base  5 , and is formed with through holes  651  corresponding to the round holes  61  in respect of position; the screws  63 ,  64  are passed through the holes  651 , and then screwed into the threaded hollow post  483  of the rotary locating shafts  48  so that the rotary locating shafts  48  are fixedly connected to the spring base  65 ; the spring base  65  is formed with holding tunnels  652  on two lateral sides, in which springs  66  are disposed to bias the spring base  65  upwards; an extending tube  67  is provided, which has screw threads  671  on an inner side, and which is positioned around a lower tube portion  641  of the screw  64 ; the lower tube portion  641  is formed with threads on an inner side, and a bolt  68  is passed into the extending tube  67  and screwed into the tube portion  641 ;  
         [0040]    the inward housing part  7  has a subsidiary plate  71  positioned above it, and has a connecting hole  72 ; an outer base body  73  is fitted on an outer end of the connecting hole  72 , which body  73  has a connecting hole  731  on one side, and a polygonal engaging post  732  on the other side; an inner base body  74 , and an adjustment rod  75  are arranged between the inward housing part  7  and the subsidiary plate  71 ; the inner base body  74  has opposing sloping guide trenches  742  on an annular side  741  thereof, and is joined to the outer base body  73  with a screw  743 , which is passed through the body  74 , and screwed into the connecting hole  731 ; the adjustment rod  75  has a first threaded end portion  751  screwed to the inner threads  671  of the extending tube  67 , a second end portion, and a pull pin  752  transversely passed through and joined to the second end portion; the pull pin  752  is fitted into the sloping guide trenches  742  of the inner base body  74  at two ends; a knob  76  is provided for setting the unlocking combination of the present lock; the knob  76  has a connecting hole  761 , into which the polygonal engaging post  732  of the outer base body  73  is fitted, as shown in FIG. 12; thus, movement can be passed on to the rotary locating shafts  48  as well as the spring base  65  via the outer base body  73 , the inner base body  74 , the adjustment rod  75 , the extending tube  67 , and the screw  64  to make the same move towards the inward housing part  7  when the knob  76  is turned.  
         [0041]    In assembling the lock, referring to FIGS.  4  to  9 , the clear button  13 , confirmation button  18 , numbered buttons  14 , lock plate cover  15 , ringed lock plates  16 , rotary bases  17 , inner base  2 , push plate  3 , main recover base  4 , bottom base  5 , and bottom cover  6  are joined to the outward housing part  1  as above mentioned, and the outward housing part  1  is secured to an outward side of a door  8  while the inward housing part  7  is arranged on an inward side of the door and fitted to the outward housing part  1 .  
         [0042]    To unlock the lock, the user has to press each of buttons  14  of the unlocking numeral combination for correct numbers of times. For instance, the unlocking numeral combination is set as 1, 3, 5, and the correct numbers of times, for which the unlocking buttons have to be pressed are 5, 3, 1 respectively, the user has to pressed button  14  denoted with “1” five times, button denoted with “3” three times, and button denoted with “5” one time to unlock the lock. The rotary bases  17  are each formed with eight guide trenches  172 , and the rotary locating shafts  48  are each formed with eight engaging trenches  482  in the present embodiment. And, in order for the knob mechanism  11  to be capable of moving the push plate  3  to unlock the door  8 , all of the ringed lock plates  16  have to be turned until the flat portions  161  are faced with the curved recess portions  32  of the push plate  3  to not stop the push plate  3  from moving; the knob  111  can also turn to make the dead bolt  81  move together with it for unlocking the door  8 .  
         [0043]    Referring to FIGS. 10, and  11 , when the numbered buttons  14  are pressed, the rotary shafts  143  will move down; the rotary basses will rotate at the same time to make the ringed lock plate  16 , rotary control elements  47 , and rotary locating shafts  48  to turn together with them for a same angle because the protrusions  1435  of the rotary shafts  43  are engaged with the sloping guide trenches  172  of the rotary bases  17 , and in turns, the rotary locating shafts  48 , rotary control elements  47 , ringed lock plates  16 , and rotary bases  17  will be held in position after they have been pressed down and turned for above mentioned angle by means of elastic engagement of the locating pins  492  of the recover base  49  with the engaging trenches  482  of the rotary locating shafts  48 . When the numbered buttons  14  are released after having been pressed, the upper pistons  141 , caps  142 , and rotary shafts  143  are forced to move up back to original position by means of the springs  147 ; the rotary shafts  143  will rotate in a reverse direction on the course of moving back to the original position because the protrusions  1435  thereof will be guided by the guide trenches  172  of the rotary bases  17 , and in turns, torsion is stored on the springs  146  until the protrusions  1435  separate from the guide trenches  172 , and the springs  146  will make the rotary shafts  143  rotate for certain angle when the protrusions  1435  separate from the sloping guide trenches  172 ; the above rotation of the rotary shafts  143  is limited by means of the curved bars  1413  of the upper pistons  141  stopping the curved protrusions  1432  of the rotary shafts  143 , ensuring that the protrusions  1435  of the rotary shafts  143  easily fit onto the sloping guide trenches  172  when the user again presses the numbered buttons  14  to make the ringed lock plate  16 , rotary bases  17 , and rotary control elements  47  rotate for certain angle. After buttons  14  denoted with “1”, “3”, and “5” are pressed five times, three times, and one time respectively, flat portions  161  of corresponding ringed lock plates  16  will be away from the corresponding curved recesses  32  of the push plate  3  for five times the mentioned certain angle, three times the mentioned certain angle, and one times the mentioned certain angle respectively, as shown in FIG. 9. Then, referring to FIG. 12, the unlocking combination setting knob  76  is turned to cause the inner and the outer base bodies  74 , and  73  to turn together with it; because the adjustment rod  75  cannot turn, the edges of the sloping guide trenches  742  of the inner base body  74  will exert force on two ends of the pull pin  752 , and in turns, the adjustment rod  75  moves, and movement of the adjustment rod  75  is passed on to cause the spring base  65  to move via both the extending tube  67  and the spring  64 ; thus, the rotary locating shafts  48 , which are supported with the spring base  65 , also move so that the engaging holes  481  of the rotary locating shafts  48  are separated from, and no longer move together with, the polygonal engaging projections  473  of the rotary control elements  47 ; after the rotary locating shafts  48  are disengaged from the rotary control elements  47 , the rotary control elements  47  are made to rotate back to original position by the springs  475 , and cause the ringed lock plate  16 , and rotary bases  17  to rotate back to original position at the same time. Then, the unlocking combination setting knob  76  is released so that the spring,  66  biases the spring base  65  upwards to original position, and the rotary locating shafts  48  above the spring base  65  also move up, and the engaging holes  481  of the shafts  48  engage the polygonal engaging projections  473  of the rotary control elements  47  again; at the same time, the spring base  65  makes the adjustment rod  75  move up together with it, and in turns, the inner and the outer base bodies  74 ,  73 , and the unlocking combination setting knob  76  are forced to rotate to original position in reverse direction. Then, referring to FIG. 17, the clear button  13  is pressed so that the slope  1311  of the lower push post  131  exert force on the slope  43  of the main recover base  4  to make the main recover base  4  move towards the second end while the equidistantly spaced push protrusions  46  of the main recover base  4  are separating from the sloping trenches  494  of the recover base  49  gradually to cause the recover base  49  to move outwards at the same time; thus, the locating pins  492  are on longer fitted in the engaging trenches  482  of the rotary locating shafts  48 , and the rotary locating shafts  48  are released, and turned back to the original position by the springs  485 ; because the rotary bases  17 , rotary control elements  47 , and ringed lock plates  16  are associated with the rotary locating shafts  48  in movement, they will continue rotating such that the flat portions  161  of the ringed lock plates  16  associated with the buttons  14  denoted with “1”, “3”, and “5” no longer face the curved recess portions  32  of the push plate  3 , and will be away from the corresponding curved recesses  32  of the push plate  3  for five times the mentioned certain angle, three times the mentioned certain angle, and one times the mentioned certain angle respectively. Thus, setting of the unlocking combination is finished as shown in FIG. 13.  
         [0044]    The push plate  3  will be still engaged with the ringed lock plates  16  to be incapable of moving, and in turns, the confirmation button  18  can&#39;t be pressed down in case all of the numbered buttons of the unlocking combination are not pressed respective correct numbers of times; at the same time, the cylindrical portions  1145  of the rotary gear  114  is still held in the polygonal engaging hole  1135  of the fixing base  113  therefore the knob mechanism  11  fixedly joined to the fixing base  113  can&#39;t make the rotary gear  114  move together with it to move the push base  115 , only capable of turning in idle manner.  
         [0045]    For a person to unlock the door  8  who is outside the room, he first has to press the buttons  14  denoted with “1”, “3”, and “5” five times, three times, and one time respectively; when the buttons  14  are pressed, the protrusions  1435  of the rotary shafts  143  will be fitted into the guide trenches  172  of the rotary bases  17 , and work with the sloping sections of the guide trenches  172  to make the rotary bases  17  rotate for a certain angle, and in turns, the ringed lock plates  16 , rotary control elements  47 , and rotary locating shafts  48  rotate for the same angle together with the rotary bases  17 ; at the same time, the rotary locating shafts  48 , rotary control elements  47 , ringed lock plates  16 , and rotary bases  17  will be held in position after they have been pressed down and turned for above mentioned angle due to the elastic engagement of the locating pins  492  of the recover base  49  with the engaging trenches  482  of the rotary locating shafts  48 . When the buttons  14  are released, the rotary shafts  143  are forced to move up back to the original position by means of the springs  146 , and  147 , and rotate in a reverse direction on the course of moving back to the original position because of the guide trenches  172  of the rotary bases  17 . Because the buttons  14  denoted with “1”, “3”, and “5” are pressed five times, three times, and one time respectively, the corresponding ringed lock plates  16  will rotate for five times the certain angle, three times the certain angle, and one times the certain angle respectively so that flat portions  161  thereof face corresponding curved recess portions  32  of the push plate  3 , as shown in FIG. 8, and in turns, the push plate  3  is no longer stopped by the ringed lock plates  16 . Then, referring to FIG. 14, the confirmation button  18  is pressed to move the actuating rod  181  downwards so that the slope  1815  of the actuating rod  181  is pressed against the pushing slope plate  39  of the push plate  3  to make the push plate  3  slightly move towards the second end; when the push plate  3  is moved, the sloping portions  301  thereof will be pressed against the slopes  1143  of the rotary gear  114  so that the rotary gear  114  moves upwards, and the polygonal engaging portion  1144  of the gear  114  is engaged with the polygonal engaging hole  1135  of the fixing base  113  for the gear  114  to be capable of moving together with the fixing base  113 . Thus, referring to FIG. 16, the rotary gear  114  can be turned to make the push base  115  to move the push plate  3 , and make the co-moving plate  82  move the dead bolt  81  for unlocking the door  8  by means of the turning the knob  111 . When the confirmation button  18  is pressed to move the actuating rod  181  downwards, the engaging pin  185 , which is stopped by the downwards extended plate  29  of the inner base  2 , will be directed to, and inserted into, the though hole  291  of the plate  29  so that the actuating rod  181  is fixed in position after the downward movement; referring to FIG. 15, when the knob  111  is turned to make the push base  115  move the push plate  3  towards the second end, the pushing protrusion  38  of the push plate  3  will be passed into the through hole  291  of the inner base  2  to push the engaging pin  185  away from the through hole  29 , thus allowing the actuating rod  181  to move back to the original position due to elasticity of the spring  187 . Furthermore, the downwards extending pushing plates  35  will make the main recover base  4  towards the second end when the push plate  3  is moved towards the second end by means of the knob  111 , and in turns, the push protrusions  46  of the main recover base  4  gradually separate from the sloping trenches  494  of the recover base  49 , and at the same time push the recover base  49  outwards to make the locating pin  492  disengage the engaging trenches  482  of the rotary locating shafts  48 ; thus, the rotary shafts  48  are released, and the springs  485  make the rotary shafts  48  rotate back to the original position; because the rotary locating shafts  48 , rotary control elements  47 , ringed lock plates  16 , and rotary bases  17  can move together with each other, the rotary control elements  47 , ringed lock plates  16 , and rotary bases  17  associated with the buttons  14  denoted with “1”, “3”, and “5” now rotate in reverse directions for five times the certain angle, three times the certain angle, and one times the certain angle respectively to the original position, and the buttons  14  denoted with “1”, “3”, and “5” have to be respectively pressed five times, three times, and one time for unlocking the door  8  again.  
         [0046]    Not all of the flat portions  161  of the ringed lock plates  16  will face the curved recess portions  32  of the push plate  3 , and the push plate  3  will be stopped from moving by the ringed lock plates  16  if the buttons  14  are not pressed according to the unlocking combination. Consequently, the door  8  can&#39;t be unlocked by means of turning the knob  111 . After the buttons  14  have been pressed wrongly, the user first has to press the clear button  13  for allowing the numbered buttons  14  to be operated again to unlock the door  8 ; referring to FIG. 17, when the clear button  13  is pressed, the slope  1311  of the lower push post  131  will be pressed against the slope  43  of the main recover base  4  to make the main recover base  4  move towards the second end, and in turns, the equidistantly spaced push protrusions  46  of the main recover base  4  cause the recover base  49  to move outwards, and the locating pins  492  are on longer fitted in the engaging trenches  482 , i.e. the rotary locating shafts  48  are released; after the locating shafts  48  are released, the rotary control elements  47 , ringed lock plates  16 , rotary bases  17 , and locating shafts  48  are moved back to the original position where the buttons  14  are not pressed.  
         [0047]    From the above description, it can be easily understood that although the present lock is equipped with only five numbered buttons, generally fewer than conventional combination locks, it can be set with more different unlocking combinations than a conventional combination lock equipped with more, e.g. ten, buttons because each of the buttons in the unlocking combination has to be pressed correct numbers of times for unlocking. Therefore, the present lock can effectively prevent thieves from finding out the unlocking combination.  
         [0048]    Furthermore, the present lock is easy and convenient to use because no other tools are needed to set the unlocking combination.  
         [0049]    In addition, the rotary gear  114  is not engaged with the fixing base  113  fixedly joined to the knob  111 , and the knob can only be turned in idle manner without actuating the push base  115  and the co-moving plate  83  if the buttons  14  are not pressed according to the unlocking combination. Therefore, a thief cannot force the lock to unlock by means of turning the knob  111  violently.