Abstract:
The breech lock unit has a housing in which a strike hammer is mounted so that it can be pivoted around a shaft. A drive lever can be pivoted on the same shaft to a limited extent in both directions with respect to the hammer. The hammer is biased by a spring against the one stop with the lever. Connected to the lever is a connecting rod which is biased by a striker spring and in the base position is in contact with a stop surface on the housing. The configuration described above makes possible a slim construction and optimum drive conditions. A plurality of functions that conventionally require separately installed components can be realized in the one breech lock unit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a breech lock mechanism for a pistol with a breech mechanism that can be moved on a grip piece, in which breech mechanism a firing pin is movably mounted and which, in its base position, projects beyond a rear end surface of the breech mechanism. 
     2. Description of the Currently Available Technology 
     EP-A-0 013 583 describes a trigger mechanism that is integrated into the grip of the pistol. A strike hammer can pivot around a shaft. A drive ring that can pivot to a restricted extent with respect to the hammer is pivotably mounted on the same shaft. An additional spring is inserted between the ring and the strike hammer. The trigger interacts with a ratchet lever that is engaged in a notch of the ring. When the hammer is cocked, it can be pivoted forward against the force of the second spring, where it engages with a pin on a hook of the trigger mechanism. When the trigger is pulled, first the pin is released, so that the hammer accelerates back into its cocked position, before the ring is released if the trigger is actuated further. It thereby becomes possible to do without a double-action trigger. In the base position of the hammer, in which it is pivoted forward, however, both springs are fully cocked. In the event of a sharp impact on the pistol, e.g. if it is dropped or falls on a hard surface, the vibration can cause the pistol to fire, which is dangerous. The vibration caused by the impact of the ring against the hammer immediately before the shot is fired also has a disadvantageous effect on the aiming accuracy and security of firing. 
     An object of the invention is to create a breech lock mechanism that provides increased safety. This object is accomplished by the combination of features disclosed in the claims. 
     SUMMARY OF THE INVENTION 
     A breech lock unit is provided for a pistol with a breech mechanism guided movably on a grip piece, in which breech mechanism there is a firing pin that is movably mounted and in a base position projects beyond a rear end surface of the breech mechanism. The breech lock unit includes a housing and a strike hammer mounted in the housing and pivotable around a first shaft. A drive lever is mounted such that the drive lever is pivotable around the first shaft and is pivotable with respect to the strike hammer such that when a shot is discharged, the drive lever drives the strike hammer by a first stop. A return spring is positioned between the drive lever and the strike hammer and is configured to apply a load to the hammer in a direction of the first stop. A striker rod is connected to the drive lever at a distance from the first shaft. A biased striker spring is configured to apply a load to the striker rod in a direction of a firing position of the strike hammer and is supported on the housing. A second stop is configured to stop the movement of the drive lever before the strike hammer strikes the firing pin. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained in greater detail below, with reference to the exemplary embodiment illustrated in the accompanying drawings, in which: 
     FIGS. 1 to  3  show a breech lock mechanism in cross sections through various planes in the base position, 
     FIGS. 4 to  6  are illustrations of the breech lock mechanism illustrated in FIGS. 1 and 2 in the firing position and in the cocked position, 
     FIGS. 7 to  9  illustrate the function of the uncocking lever, and 
     FIG. 10 is a view of the pistol in perspective. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The breech lock mechanism  10  illustrated in the accompanying figures is inserted as a self-contained unit into the pistol grip  61  of a grip  60  of the pistol. Movably mounted on the grip  60  is a breech mechanism  11  in which the barrel is mounted. A firing pin  12  is capable of moving inside the breech mechanism  11 , and is biased by a force applied by a spring in its rear base position illustrated in FIGS. 1,  2  and  5 , in which it projects beyond a rear end surface  9  of the breech mechanism  11 . The breech lock unit  10  has a housing  13 . In the housing  13 , a stroke hammer  14  is mounted so that it can pivot around a first shaft  15 . A drive lever  16  can pivot on the same shaft  15 . The pivoting motion of the lever  16  with respect to the hammer  14  is restricted by two stop surfaces  17 ,  18  of the hammer  14  in the two directions of rotation. The strike hammer  14  is biased by a spring  19  with respect to the lever  16  toward the rear against the first stop or stop surface  17 . A percussion rod  22  is connected to the lever  16 , at some distance from the shaft  15 . The rod  22  is guided in a boring  23  of a transverse web  24  of the housing  13 . 
     Between a disc  25  secured on the end of the rod by a transverse pin and the web  24 , the prestressed striker spring  26  is inserted, which applies tension to the rod  22 . In the base position illustrated in FIGS. 1 to  3 , a second stop or stop surface  27  of the rod  22  is in contact against the web  24 . The strike surface  28  of the hammer  14  in this base position is at an angle of approximately  150  with respect to the rear end surface  9  of the breech mechanism  11  so that, if the breech mechanism  11  is pushed backward by an impact, the hammer  14  cannot strike the firing pin  12 . The hammer  14  is engaged with a first catch  31  in a spring-loaded pawl  29 . The lever  16  has some play with respect to the contact surface  17 . 
     The hammer  14  interacts in a known manner with a trigger rail  32 . In the housing  13 , a slide  33  is mounted so that it can be displaced, and presses the rail  32  by means of a spring  34  in engagement into a catch  35  of the hammer  14 . An uncocking lever  36  is also rotationally mounted on a second shaft  44 . By means of the uncocking lever  36 , the hammer  14  can be pivoted back out of the cocked position illustrated in FIG. 5 into the base position illustrated in FIGS. 1 to  3 . Also fastened to the housing  13  is an ejector mechanism  37  which, after the shot has been fired, ejects the empty cartridge through an opening in the breech mechanism  11 . 
     The breech lock unit  10  functions as follows: When the trigger is pulled, the rail  32  is pulled forward. It pivots a safety lever  42  (FIG.  6 ), which can also pivot around the shaft  15  and presses a safety slide  43  out of a locking catch  45  of the firing pin  12 , on which a downward load is exerted by a spring  46 . The lever  42  presses the pawl  29  forward out of its engagement with the catches  31 ,  38 . The rail  32 , by means of its engagement in the recess or catch  35 , drives the hammer  14  against the force of the spring  26  into the cocked position illustrated in FIG.  5 . The rail  32  runs along a control cam  47  (FIG.  6 ), which displaces it against the force of the spring  34  downward and out of engagement with the catch  35 . The hammer  14  is released, so that the spring  26 , by means of the impact rod  22  acting as a connecting rod, the lever  26  and the stop surface  17 , accelerates the hammer  14  against the breech mechanism  11 , until the surface  27  comes into contact against the web  24 . As a result of the mass inertia of the hammer  14 , said hammer  14  continues to rotate, strikes the firing pin  12  and initiates the firing process. After the shot has been fired, the breech mechanism  11  slides back and the empty cartridge shell is ejected. The process described above is conventionally called “double action” (DA). When, after the shot has been fired or as a result of manual action, the breech mechanism slides backward, a control cam of the breech mechanism pivots the trigger rail  32  downward and the hammer  14  backward, so that the hammer is engaged with the second catch  38  on the pawl  29 . When the trigger is released, the rail  32  slides backward into engagement with the lever  42  which, the next time the trigger is actuated, pushes the pawl  29  out of the catch  38  after it moves past the DA firing position (single action). 
     FIGS. 7 to  9  illustrate the function of the uncocking lever  36 . FIG. 7 shows the uncocking lever  36  in the base position and the strike hammer  14  in its safety position as illustrated in FIGS. 1 to  3 , in which the pawl  29  is engaged in the safety catch  31 . The uncocking lever  36  has an arm  48  with a second means, e.g. a projecting lug  49 , which interacts with a slide surface of the strike hammer  14 . A first means, e.g. a trigger tab  51 , projects forward from the arm  48 . When the grip  52  of the uncocking lever  36  is depressed, the trigger tab presses against a web  53  of the pawl  29 . When the hammer  14  with its single-action catch  38  is engaged in the pawl  29 , the pawl  29  is thereby pivoted out of engagement with this catch  38 . FIG. 8 shows this process immediately before the release of the hammer  14 . As the uncocking lever  36  pivots further, the hammer  14  is released, so that the slide surface  50  impacts the lug  49  (FIG.  9 ). As the uncocking lever  36  pivots back, the hammer  14  is gently returned by the sliding of the lug  49  on the surface  50  and simultaneously the pawl  29  is released once again, so that it engages in the catch  31  (FIG.  7 ). 
     FIG. 10 illustrates the installation of the breech lock unit  10  into the grip piece  60  of the pistol. The grip piece  60 , in the pistol grip  61 , has a magazine shaft  62  that runs at an angle to the axis for the insertion of a magazine, which is closed at the back by a rear wall  63 . The two side walls  64  that continue beyond the wall  63  have grooves  65  with a rectangular cross section that run parallel to the wall  63 . The breech lock unit  10 , on the forward edge on both sides, has two molded rails  66  that project laterally and fit into the grooves  65 . The breech mechanism  11  is guided in two additional rails  67  on the upper edge of the housing  13 . The breech lock unit  10  is inserted from above into the grip piece  60  and is secured by two cross-bolts  68 ,  69  which are inserted through transverse borings  70  to  72  in the two side walls  64  and in the housing  13 , or recesses  73  in the housing  13 . FIG. 10 also shows the trigger tab  74 , which is pivotably mounted in a front insert (not shown). The front insert also has lateral rails that correspond to the rails  67  to guide the breech mechanism  11 . The trigger rail  32  is pivotably connected to the trigger tab  74 . 
     Because the striker rod  22  transmits the spring force by tension, and the point of application of force of the striker rod  22  with respect to the hammer  14  is therefore in front of the shaft  15 , the breech lock unit described above is slimmer than is possible with the pressure transmission mechanisms of the prior art, and optimal drive conditions are achieved, because the striker rod  22  in the pistol grip must be installed inclined downward and toward the rear. By integration of the slide  33  into the trigger rail  32  of the uncocking lever  36 , of the safety lever  42  and of the ejector mechanism  37 , a plurality of functions can be combined in one compact unit, which simplifies manufacture. 
     Because the hammer  14  in the base position is locked in the safety catch  31  and the striker rod  22  is stopped against the stop  24 , there is multiple protection against an unintentional discharge. A first safety measure is the above referenced protection provided by the inclination of the striking surface  28 . A second safety measure is the securing of the firing pin by the safety slide  43 . A third safety measure is provided by the uncocking lever  36 . If the person using the pistol uncocks the strike hammer by holding it back, actuating the trigger and then slowly returning the hammer  14 , after the trigger has been released, the hammer  14  is automatically returned to the safety catch  31 . Because the breech lock unit  10  is inserted into the grip piece  60  as a pre-assembled unit, it can easily be replaced by another breech lock unit  10 , for example so that the original can be repaired. It is also possible to prepare a plurality of different breech lock units  10 , e.g. in addition to the unit described above, a unit can be used that does not have the catch  38 , so that the pistol is a double-action-only pistol. Breech lock units with different impact forces can also be made available for different types of ammunition. The breech lock unit described above therefore also makes it possible to adapt the pistol to meet different requirements.