Abstract:
A mortise lock for mounting in a door. The lock includes a bolt movable along a first axis between an extended position and a retracted position. Included are means for biasing the bolt to its extended position. The lock further includes a driven member which is mounted for rotation about a second axis generally perpendicular to the first axis. As the driven member is made to rotate about the second axis, it engages the bolt and urges it, overcoming the bias, to its second position. A drive member is mounted for rotation about a third axis, generally parallel to the second axis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a regular application filed under 35 U.S.C. §111(a) claiming priority, under 35 U.S.C. §119(e)(1), of provisional application Ser. No. 60/983,442, previously filed Oct. 29, 2007 under 35 U.S.C. §111(b). 
    
    
     TECHNICAL FIELD 
     The present invention is a door mortise lock. The mechanism described is related to a latch used in a door to constrain it closed, when in an extended position, and allow door opening when in a retracted position. 
     BACKGROUND OF THE INVENTION 
     Latches carried by a door to effect secure locking are very common. They typically include a latch bolt enclosed within a housing. Many are rotationally actuated and bi-directional. This means they are actuated by either clockwise or counter-clockwise handle rotation. In a neutral or un-actuated position, the bolt is extended from the housing and precludes door opening when the bolt is engaged in a typical strike plate. Handle rotation retracts the latch bolt to disengage the bolt from the strike plate and allow the door to be opened. Typically, closing of the door imparts a force upon the bolt by the strike plate or door frame to retract the bolt without manual handle rotation being required. 
     Many latch mechanisms today rely on cams for actuation. This involves the generation of friction between cam body surfaces and creates wear under conditions of cyclical use. Additionally, some mechanisms require significant handle rotation (more than 45°) to retract the bolt within its housing. What is needed, therefore, is a latch mechanism which retracts the latch bolt with less than 45° rotation and eliminates frictional wear typically brought to bear upon sliding cam surfaces. The present invention offers solutions to these problems. 
     SUMMARY OF THE INVENTION 
     The present invention is a mortise lock which employs a gear latch bolt mechanism which includes at least one toothed member received in a latch-housing. A handle is mechanically coupled to a drive member for moving the bolt between an extended and a retracted position. The mechanism also includes a driven member, actuable by the drive member, which acts upon the bolt to move it from a first, extended position to a second, retracted position. Both the drive member and the driven member may employ involute gear profiles. As a result, rotation of the drive member imparts force to the driven member with only minimal frictional force at a location of engagement. The driven member then linearly retracts the bolt by means of a projection extending from the driven member into a receiver of the bolt. 
     The mechanism described can incorporate two sets of drive and driven members, which can be substantially identical to each other, to retract the bolt. Such a construction allows for bi-directional actuation (that is, either clockwise or counter-clockwise handle rotation) to retract the bolt. It will be understood that the handle rotational angle required to retract the bolt is a function of the geometry of the driven member related to the bolt. 
     The present invention is thus an improved mortise lock mechanism. More specific features and advantages obtained in view of those features will become apparent with reference to the Detailed Description of the Invention, appended claims and accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of the present invention; 
         FIG. 2  is an alternate perspective view of the structure of  FIG. 1 ; 
         FIG. 3  is an exploded isometric view of the invention; 
         FIG. 4  is an isometric view of the mechanism housing; 
         FIG. 5  is an isometric view of the mechanism cover; 
         FIG. 6  is an isometric view of the mechanism bolt; 
         FIG. 7  is an alternate perspective view of the structure of  FIG. 6 ; 
         FIG. 8  is an isometric view of the mechanism drive member; 
         FIG. 9  is an isometric view of the mechanism driven member; 
         FIG. 10  is a perspective view of the mechanism with the bolt extended and the cover removed; 
         FIG. 11  is a side view of the mechanism with the bolt retracted and the cover removed; and 
         FIG. 12  is a side view of the mechanism with the bolt retracted as a result of driven member rotation, and the cover removed; and 
         FIG. 13  is a straight-on side elevational view of the mechanism with the bolt extended and the cover removed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 3  and appended Component Description List, illustrated are the basic components of the present gear latch-bolt mechanism  100 . Included are a housing  110 , bolt springs  250 A and  250 B, two drive members  170  ( 170 A and  170 B individually), two driven members  190  ( 190 A and  190 B individually), a bolt  150  and a cover  130 . It will be understood that a reference numeral without suffix A or B is intended to refer collectively to similar components, while, where suffix A or B is used, the intent is to refer to only one of the components individually. 
     The latch assembly is more specifically described referring to  FIGS. 3-9 . A drive member  170 A has a drive bearing  172  which is inserted in the housing  110  opening  114 , shown in  FIG. 4 , and positioned with the drive tooth  180  oriented extending toward the bolt opening  118 . The driven member  190  post receiver  192  is positioned over the housing post  112  such that the roll post  202  is positioned similar to the orientation shown in  FIG. 3  for driven member  190 A. The bolt wear surface  164  is fed into the housing bolt opening  118  and placed such that the roll post  202  of the driven member is received within the peg receiver  166 . The identical drive member  170 B is then positioned over the first drive member  170 A such that the alignment guide  174  from the drive member  170 B aligns with the alignment receiver  176  of the drive member  170 A. It will be understood that the alignment guide  174  would align with the alignment receiver  176  of the drive member  170 B. The drive members are then in engagement with the respective planar surfaces  178 A and  178 B touching. The interlocking feature eases spindle insertion but is not required for latch functionality. The second driven member  190 B which is substantially identical to driven member  190 A is then positioned by aligning the post receiver  192  with the post  112  such that the roll post  202  of driven member  190 B is received within the peg receiver  156  of the bolt. It will be understood that the length of peg receiver  156  along its axis and the length of the upper extending portion of driven member  90 B are such that the driven member extension will always remain captured in peg receiver  156  so as to preclude a lockout situation. The two identical bolt springs  250  are then inserted such that they are linearly constrained by the bolt spring supports  160  and  161 , and the spring guides  155  and  158  and the spring receiver  116  of the housing and the spring receiver  142  of the cover  130 . It should be understood that the bolt springs exert a force upon the bolt that biases the bolt toward an extended position. The cover  130  bolt end  132  is then inserted in the bolt opening  118 , and the cover post opening  134  is positioned over the post  112  in conjunction with the drive bearing  172  of the drive member  170 B being positioned within the gear opening  136  of the cover. The post  112  is then deformed to constrain the cover  130  to the housing  110  encapsulating the latch components. 
     The discussion above applies to  FIG. 13  as well as to  FIG. 10 .  FIG. 10  better shows the gap, however, between each drive member and a corresponding driven member,  FIG. 13  being straight on. 
     The function of the latch is described below. The cover is not shown in  FIGS. 10-12  to allow understanding of internal component interaction. Referring to  FIG. 10 , the latch is shown in the neutral or un-actuated position in which the bolt is in an extended position relative to the housing. In this position, the compression springs are shown in a pre-loaded, but extended position. The drive members are in a neutral position. The driven members are in a float position and are rotationally limited by the drive member and bolt peg receiver geometry. The bolt is restricted from extending further due to the interaction of the housing bolt stop  152  and the cover bolt stop  154  with the housing stop guide  120  and cover stop guide  140 . 
       FIG. 11  depicts the latch with the bolt retracted by means other than the rotation of a handle. Such retraction can result as from a door closing and the attendant bolt and strike or door frame interaction. As shown in  FIG. 11 , the drive members may remain in a neutral position, but the driven members are rotated as a result of interaction of the bolt outer surface  157  and  167  and the roll surface  200  of both driven members  190 A and  190 B. As shown in  FIG. 11 , the driven member  190 B is rotated away from the drive member  170 B which remains in the neutral position. The bolt may be limited in retraction by the interaction of the housing and cover bolt stops. Also, the contact of the bolt rear stop  169  with the housing rear wall  122 . 
     Referring to  FIG. 12 , the latch is shown with the bolt retracted by means of the driven member rotation in a counter-clockwise direction. This is typically accomplished by means of a handle with a spindle attachment insertable through the spindle receiver  182  of the drive member. In this figure it is seen that the tooth of the drive member interacts with the driven member, and the roll guide  194  engages the inner surface  159  and retracts the bolt within the latch. This causes the bolt springs to be compressed such that, when the rotational force on the drive member is released, the bolt is again biased to an extended position. The functioning of the latch is similar for clockwise handle rotation as viewed in  FIG. 12 . The difference is that the acting drive member is  170 A and driven member is  190 A rather than  170 B and  190 B as with counter-clockwise actuation. It has been found that it is efficient to maintain the angle through which a driven member is rotated small, typically less than 45 degrees and even less than 22 degrees. 
     It will be understood that the driven member, irrespective of which force transmission train is operative, functions as a first-class lever. That is, forces applied to an extension of the driven member by the corresponding drive member extending on a side of the axis of rotation of the driven member opposite that at which a second extension of the driven member engages the bolt within its receiver. This is in contrast to prior art devices. Consequently, the present invention achieves a high level of efficiency. 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Component 
                 Feature 
                 Description 
               
               
                   
                   
               
             
             
               
                   
                 100 
                   
                 Gear Latch-Bolt Mechanism 
               
               
                   
                 110 
                   
                 Housing 
               
               
                   
                   
                 112 
                 Post 
               
               
                   
                   
                 114 
                 Gear opening 
               
               
                   
                   
                 116 
                 Spring receiver 
               
               
                   
                   
                 118 
                 Bolt opening 
               
               
                   
                   
                 120 
                 Stop guide 
               
               
                   
                   
                 122 
                 Rear wall 
               
               
                   
                 130 
                   
                 Cover 
               
               
                   
                   
                 132 
                 Bolt end 
               
               
                   
                   
                 134 
                 Post opening 
               
               
                   
                   
                 136 
                 Gear opening 
               
               
                   
                   
                 140 
                 Stop guide 
               
               
                   
                   
                 142 
                 Spring receiver 
               
               
                   
                 150 
                   
                 Bolt 
               
               
                   
                   
                 152 
                 Housing bolt stop 
               
               
                   
                   
                 154 
                 Cover bolt stop 
               
               
                   
                   
                 155 
                 Spring guide 
               
               
                   
                   
                 156 
                 Peg receiver 
               
               
                   
                   
                 157 
                 Outer surface 
               
               
                   
                   
                 158 
                 Spring guide 
               
               
                   
                   
                 159 
                 Inner Surface 
               
               
                   
                   
                 160 
                 Spring support 
               
               
                   
                   
                 161 
                 Spring support 
               
               
                   
                   
                 164 
                 Bolt wear surface 
               
               
                   
                   
                 166 
                 Peg receiver 
               
               
                   
                   
                 167 
                 Outer surface 
               
               
                   
                   
                 168 
                 Inner surface 
               
               
                   
                   
                 169 
                 Rear stop 
               
               
                   
                 170 (A&amp;B) 
                   
                 Drive Member, Housing Side 
               
               
                   
                   
                 172 
                 Drive bearing 
               
               
                   
                   
                 174 
                 Alignment guide 
               
               
                   
                   
                 176 
                 Alignment receiver 
               
               
                   
                   
                 178 
                 Planar surface 
               
               
                   
                   
                 180 
                 Drive tooth 
               
               
                   
                   
                 182 
                 Spindle receiver 
               
               
                   
                 190 (A&amp;B) 
                   
                 Driven Member 
               
               
                   
                   
                 192 
                 Post receiver 
               
               
                   
                   
                 194 
                 Roll guide 
               
               
                   
                   
                 196 
                 Driven tooth 
               
               
                   
                   
                 200 
                 Roll surface 
               
               
                   
                   
                 202 
                 Roll post 
               
               
                   
                 250 (A&amp;B) 
                   
                 Bolt Spring 
               
               
                   
                   
               
             
          
         
       
     
     It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.