Patent Publication Number: US-6340183-B1

Title: Bolt lock for mounting in a thin wall

Description:
BACKGROUND OF THE INVENTION 
     a.) Field of the Invention 
     The invention is directed to a bolt lock for mounting in a thin wall, such as a sheet metal cabinet door, comprising a handle plate which can snap into a rectangular cutout in the thin wall and which has, at one side of the rectangle, a bolt that is supported so as to be displaceable against spring force relative to the thin wall. While the foregoing description and drawings represent the present invention, it will be obvious to those skilled in the art that various changes may be made therein without departing from the true spirit and scope of the present invention. 
     A bolt lock of this kind is known to the present Applicant from Brochure Sheet G-9 by Southco, U.S.A. A bolt lock of the type mentioned above can snap into a suitably dimensioned opening in a door leaf, whereupon the door or flap can be pushed closed, wherein the bolt engages behind a case or frame to which the door is hinged. When the door or flap is pushed closed, the handle plate is displaced inside of the correspondingly dimensioned right-angled opening in the door leaf against the force of a spring which is articulated at the handle plate and which presses against the edge of the opening, wherein, as a result of the inclined surface of the bolt, this displacing movement is carried out automatically when the door or flap is pushed closed. As soon as the bolt engages behind the case or frame, the spring presses the handle plate in the opposite direction and accordingly locks the door at the door frame. 
     The known lock is available in different constructions for defined thicknesses, e.g., 1.2 mm, 1.6 mm and 2.2 mm, of the door leaf. Deviations in thickness greater than 0.2 mm are not permissible because the arrangement would then jam or rattle. 
     Nevertheless, the lock described above has the advantage that it can be mounted in a door leaf without the need for its rear side to be accessible. In other known locks for sheet metal cabinet doors or flaps, mounting requires access to the rear side of the door leaf so that a lock inserted through a corresponding opening in the door leaf from the front can be fastened to the rear side by means of a nut or an attachable spring part. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is the primary object of the invention to further develop a bolt lock of the type mentioned above in such a way that it does not require a separate series for every thickness of sheet metal, but rather can be adapted to a relatively large range of different sheet metal thicknesses without impeding operation or rattling. 
     The above object of the invention is met in that the bolt is formed by a second (inner) handle plate which is supported so as to be displaceable against spring force in the first (outer) plate which is held in the thin wall. 
     As a result of this step, the movability of the plate supporting the bolt is no longer influenced by the sheet metal thickness holding the outer plate; rather, the arrangement can be further developed such that it can be securely fastened in thin walls having a relatively large variation in wall thickness. 
     In order to fix this first, outer plate in the rectangular opening of the wall such as a door leaf, the plate has, at least at one side wall, a projection which projects beyond the outer wall plane and which can be deflected back against spring force when the plate is pressed into the sheet metal cutout in the wall plane and which forms a projection tip which contacts the inside of the sheet metal wall in a clamping manner when pressed in. As a result of this feature, the plate can snap into the rectangular cutout of the thin wall from the front without the need for the rear side of the thin wall to be accessible. The plate need not be displaceable in the rectangular cutout as in the prior art, so that the plate can be held in the wall by relatively large spring forces and friction coefficients, which benefits the stability of the arrangement. 
     Due to the fact that the second plate is mounted in the first plate so as to be displaceable against spring force, it is possible to guarantee optimum displaceability by ensuring a support which is extensively free of play, but which has sufficient ability to slide. The second plate, which can be received inside the first plate in a sliding manner, can be exchanged, if necessary, in order to adapt the bolt offset to different thicknesses of the door frame, for example. The outer plate can also be exchanged, if necessary, in case of a large variation in door thickness ranges. 
     According to a further development of the invention, the first plate can form an opening in the side wall at the side facing the bolt, wherein the second plate with the bolt supported by the second plate projects through this opening in a displaceable manner. The bolt lock can advantageously be arranged in such a way that the first plate forms an edge at the upper end of the side wall remote of the bolt, which edge projects into the inner cavity of the first plate until it forms a rear grip surface for opening the door, or the like, at least when the second plate is pulled back or deflected back into the first plate. In this case, no additional handle need be provided for opening the door (for which purpose, two hands would be required under certain conditions). Rather, the finger used to push back the second plate into the unlocked position, possibly after unlocking displacement, can engage behind this rear grip surface and exert a pulling force for swinging open the door. 
     According to yet another development of the invention, the first plate forms a cover which projects outward over the side walls of the plate on all sides and rests on the edge of the opening after the plate has been inserted into the opening in the thin wall. The rectangular cutout, which may have sharp edges, is covered by means of this step. The cover preferably has an opening for access to the second plate, this opening being arranged in such a way that it forms the rear grip surface for opening the door, or the like, when the second plate is deflected back. 
     The two side walls of the first plate which lie opposite one another and advisably form a slide guide for the second plate have two notches which face away from the cover plane vertically and enclose a tongue with a holding surface extending into the vicinity of the lower cover edge surface. In this way, there is a holding projection on both sides of the plate, which benefits the stability of the arrangement. 
     Alternatively, the side wall of the first plate lying opposite the bolt can also form notches facing away from the cover plane vertically, these notches enclosing a tongue which extends into the vicinity of the lower cover edge surface. 
     In this case, the fastening is carried out at another location, but one which can likewise ensure adequate stability. 
     This applies in particular when the first, outer plate at the side facing the bolt forms two shoulders which extend diagonally upward in the direction of the thin wall from the end faces of the two side walls perpendicular to this side and which terminate close to the plane of the thin wall so as to receive the bolt between them in a sliding manner. These shoulders contact the rear surface of the thin wall when the plate is inserted into the cutout at an inclination and thus ensure a secure hold at this location, which results in a highly stable arrangement. 
     These shoulders can be constructed in a suitable manner so as to be flexible in order to adapt to different sheet metal thicknesses to a determined extent. 
     Similarly, it is possible to adapt to different sheet metal thicknesses in that the free end of the tongues forms an inclination, which can also be provided with ribs, such that this inclination contacts the lower edge of the opening in the thin wall and accordingly securely locks the plate in the opening even when the thickness of the thin wall varies. 
     It is advantageous when a pressure spring such as a helical spring is arranged between the outer surface of the wall of the inner plate remote of the bolt and the inner surface of the wall of the outer plate remote of the bolt. In this way, the inner plate is pressed in its locking position, so that the bolt works as a door latch. In order to hold the spring in place, it can be advantageous when a shoulder for receiving one end of the helical spring is provided on the outer surface of the wall of the inner plate remote of the bolt. This shoulder can have a circular shape or can be cross-shaped in cross section, which is advantageous for technical reasons pertaining the injection molding. 
     The base of the outer plate can have an opening into which a shoulder projecting from the base of the inner plate can extend in such a way that it defines the thrusting or translational movement of the inner plate into the outer plate at least in the direction of the bolt. This prevents the bolt from being completely pressed out of the outer plate through the spring force under certain conditions. This shoulder is advisably ramp-shaped in longitudinal section, the sloping line of the ramp being directed away from the bolt. This means that the two plates can be mounted one inside the other without the need for special handling, but are then locked one inside the other so that they cannot come apart while being transported or when mounting in a door leaf. 
     The spring which reinforces the latch operation of the bolt can serve at the same time to support the tongue which holds the outer plate inside the thin wall, so as to reduce the risk that its spring force will decrease excessively over the course of time, which can happen in many plastics. 
     The invention will be explained more fully in the following with reference to embodiment examples shown in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIGS. 1A,  1 B,  1 C and  1 D show a bolt lock constructed according to the invention in connection with a door leaf in different mounting positions; 
     FIGS. 2A,  2 B and  2 C show three different views of the first (outer) plate of the bolt lock according to FIGS. 1A to  1 D, which plate forms the outer housing; 
     FIGS. 3A and 3B show two different views of the second (inner) plate forming the bolt; 
     FIGS. 4A,  4 B and  4 C show three different views of an alternative embodiment form of the bolt lock; 
     FIG. 5 shows a side view of the bolt lock according to FIGS. 4A to  4 C during the installation process; 
     FIG. 6 shows a perspective view of the outer plate (housing) of the lock according to FIGS. 4A to  4 C; and 
     FIG. 7 shows a perspective view of the second (inner) plate of the bolt lock according to FIGS. 4A to  4 C. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1A shows a bolt lock  10  which can be mounted in a thin wall such as a sheet metal cabinet door  12  or flap, wherein the bolt lock  10  is formed of a first, outer handle plate  14  which can snap into a rectangular cutout  16  in the thin wall  12 , and a second, inner handle plate or bolt device  18  which is mounted in the first, outer handle plate  14  so as to be displaceable against the force of a spring  20  opposite the direction indicated by the arrow  22  (FIG.  1 C). 
     As is shown in FIG. 1A, the outer handle plate or housing  14  has a projection  26  at the right-hand side with reference to FIG.  1 A. This projection  26  projects over the outer wall plane  24  and, when pressed into the plate  14  in the cutout  16  of the thin wall  12  (see arrow  28 ), can deflect back into this wall plane  24  against the force of a spring, for which spring  20  can also be used, and forms a projection face  30  which, when pressed in, contacts the back surface or the edge of the cutout  16  of the thin wall  12  in a clamping manner as can be seen in FIG.  1 B. The first plate or housing  14  forms an opening  32  (see also FIG. 2C) at the left-hand side, as shown in FIG. 1A, from which the bolt device  18  emerges and through which the second or inner handle plate  18  extends so as to be displaceable. The first handle plate or housing  14  further forms a cover  34  which projects over the side walls  36 ,  38 ,  40 ,  42  (see FIGS. 2A,  2 B and  2 C), so that, as can clearly be seen in FIG. 1B, this cover edge which projects out on all sides covers the edge of the cutout  16  after the housing  14  is introduced into the cutout  16  according to FIG.  1 A. 
     Further, the cover  34  has an opening  44  which is sufficiently large to allow, e.g., one finger to reach through and to access the second, inner plate or bolt part  18 , that is, the interior of the plate designated by  46  in FIG.  3 A. The opening  44  is arranged in the cover  34  in such a way that the rear plate wall  48  according to FIG. 1B lies in the area of this opening  44  and can therefore be touched when reaching through with a finger and can be pressed against this wall  48 . By pressing in this manner, the second plate  18  inside the first plate  14  can be displaced in a sliding manner against the force of the spring  20  until the position according to FIG. 1C is reached. At this point, the rear lower outer edge  50  of the second plate  18  strikes the somewhat inclined lower inner wall  52  of the first plate  14 , so that a stop is formed for the movement in the direction of arrow  22 . 
     The locking latch  54  is released from a rear grip surface  56  formed by a door frame  58  or the like by means of this displacement. Accordingly, the door leaf  12  can be taken out of or swung out of the door frame  58  (or the flap  12  can be taken out of or swung out of a machine housing  58  or the like) as is shown in FIG. 1D by arrow  60 . 
     The size and position of the opening  44  in the cover  34  is advisably determined in such a way that a strip  43  is formed which projects into the inner cavity of the plate  14  and forms a rear grip surface  41  for opening the door  12  or the like, which rear grip surface  41  is accessible at least—and advisably only—when the second plate  18  is located inside of the first plate  14  in the receded position according to FIG.  10 . It is sufficient for the strip to have a rear grip surface width B (see FIG. 4A) which makes up approximately half of the travel distance H, that is, the movement path of the second plate inside of the first plate, which is limited by stop  52  or  90 , respectively. For example, with dimensions of the arrangement in the range of 25 to 30 mm for the cover width and 50 to 60 mm for the cover length, a travel distance H equaling 5 to 7 mm, e.g., H=6 mm, has proven successful, so that dimension B would be about 3 mm. The depth of the plates should be between 10 and 15 mm in order to make it possible to reach inside comfortably. The dimensions in FIGS. 4A,  4 B and  4 C are likewise only given by way of example. 
     When the door  12  is pushed closed, the inclination  62  of the latch  54  contacting the edge  64  of the door frame  58  makes it possible for the second plate to be pushed back automatically against the force of the spring, whereupon the second plate or bolt  54  is slid into the position shown in FIG. 1B by the force of the spring so that the door is locked. 
     For purposes of the smooth running of this translational movement in the direction of arrow  22  and opposite thereto, the two opposite side walls  36 ,  38  of the first plate  14  form a slide guide for the second, inner plate  18  in that the inner surfaces of the side walls  36 ,  38  of the outer plate engage with slight play at the outer surfaces of the corresponding side walls  66 ,  68  of the second plate  18  (see FIG.  3 B). The rest of the “side walls”  42  formed by the end faces of the walls  36 ,  38  of the outer plate  14  have shoulders  70  which extend diagonally upward in the direction of the thin wall  12  and which terminate close to the lower plane  72  of the thin wall and accordingly secure the outer plate  14  inside the cutout  16 . 
     The sloping surface  74  according to FIG. 1 makes it possible for the plate  14  to be inserted diagonally into the cutout  16  and enables the subsequent swiveling in the direction of arrow  28  (see FIG.  1 B). During this swiveling movement, the shoulder  70  is advisably pressed downward in a slightly springing manner so as to form a holding device for the plate  14 , which holding device forms a frictional engagement and exerts a certain pressure. This springing action makes it possible to adapt in the desired manner to any differences in thickness of the thin wall  12  which may range between 0.8 mm and 2.3 mm, for example, On the opposite wall plane  24 , the inclined surface  30  provides for adapting to different wall thicknesses of the wall  12  in that the surface  30  is swiveled outward to a greater or lesser extent, depending on the wall thickness of the surface  30 , due to its inherent springing action. The holding action of the projection surface  30  can be reinforced by ribs which are formed thereon and which are indicated in FIG. 2C by reference number  76 . 
     In order to provide the projection  26  with the springing action described above, the wall  40  located opposite the bolt latch  54  is provided, according to FIG. 2B, with two notches  78 ,  80  facing away from the plane of the cover  34  vertically, resulting in a tongue which joins at the base  82  of the plate  14  and which exhibits a springing action by reason of its material (plastic) and therefore makes it possible at the upper end of this tongue which carries the projection  26  to deflect back into the interior of the plate  14  and accordingly to insert the plate  14  into the cutout  16  of the thin wall  12  according to FIG. 1A. A shoulder  86  which proceeds from the wall  84  remote of the bolt latch  54  and on which the helical spring  20  can be mounted in a suitable manner serves, for example, to hold the helical spring  20  according to FIG. 1A in the position shown in this Figure. The shoulder  86  is ouffitted with a cross-shaped (instead of a circular) cross section in this case for technical reasons pertaining to injection molding. 
     The other end of the helical spring  20  is supported on the inner surface of the wall  52  of the outer plate  14 , namely, as was already mentioned, in the area of the tongue carrying the projection  76 , so as to reinforce its springing action, which it already possesses because of its material properties, as was already mentioned. 
     This prevents a reduction in the material spring action due to material fatigue. 
     The base  82  of the outer plate  14  has an opening  88  whose edge  90  which is directed toward the latch end  54  cooperates in such a way with a shoulder  92  projecting from the base  82  of the inner plate  18  that the translational movement of the inner plate  18  inside the outer plate  14  in the direction of the bolt  54  (opposite the direction of arrow  22  in FIG. 1C) is limited in a position which is shown in FIG.  1 B. In this way, the inner plate  18  is prevented from sliding out of the outer plate  14  completely. The shoulder  92  is advisably shaped as a ramp in longitudinal section, wherein the sloping line of the ramp is directed away from the latch  54 . This makes it possible for the inner plate  18  to slide into the outer plate  14  more easily when the bolt lock is assembled. The shape of the latch  54 , especially the offset or receiving area  94  formed by this latch  54  (see FIG.  1 C), can be adapted to the thickness of the frame  58 . In particular, it is possible to keep inner plates  18  with differently shaped notches  94  in stock and to combine them with the outer plate  14  as needed. In this case, a standardized larger shape of the outer plate  14  in which differently shaped inner plates  18  are inserted can be used for different thicknesses of the frame  58 . 
     While the can-shaped part  46  of the inner plate  18  supported inside the outer plate  14  has thin walls, e.g., of injection-molded plastic, the latch  54  is formed in that the base  82  continues forward, veers downward, forms the slope  54  and then the offset area for receiving the frame  58  and, finally, passes into a straight-line surface  96  which then veers back again at  98  in adapting to the slope of the shoulders  70  (see FIG.  1 B). These multiply-bent portions are reinforced by an inner wall  100  extending vertical thereto. 
     FIGS. 4A to  4 C show an alternative embodiment form in which fastening tongues with beveled projection surfaces  130  proceed from the side walls  136 ,  138 . For the rest, the arrangements are carried out similarly to those described above.