Protective apparatus for a lock and a lock including such apparatus are disclosed. The protective apparatus comprises a plate-like element adapted to be added to a standard lock without requiring any mounting structure not already present in the lock. A spring causes the plate-like element to move or pivot when the connecting bar of the lock is removed to block the opening through which the lock connecting bar extends into the housing. Thereby, the plate prevents insertion of a tool such as a screwdriver into the lock. In some embodiments, the protective apparatus locks the bolt when the connecting bar is removed.

BACKGROUND OF THE INVENTION 
     The present invention relates to lock apparatus, in general, and in particular to protective apparatus for lock apparatus and lock apparatus including protective apparatus. 
     SUMMARY OF THE INVENTION 
     A protective device or apparatus for a door lock is provided which is placed into the lock and is able to protect the slot through which the connecting bar of the lock extends to the lock mechanism in the housing from the lock cylinder when the connecting bar is removed. The protective device can also lock the bolt when the connecting bar is removed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a section view of a lock mounted to a door showing the free space between the door and the lock. 
     FIG. 2 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing one embodiment of a protective device which is rotated about a screw of the lock by a spring and locked in the rotated position. 
     FIG. 3 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which is rotated about a screw of the lock by a spring and locked in the rotated position. 
     FIG. 4 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which is rotated by a cam and locked in the rotated position. 
     FIG. 5 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which is rotated about a screw of the lock by a cam and locked in the rotated position. 
     FIG. 6 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which is moved by a spring as directed by a cylindrical projection of the lock and locked in the moved position. 
     FIG. 6A is a side view of the lock of FIG. 6. 
     FIG. 7 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which uses blinds which are rotated by a spring about the screw of the lock and locked in their terminal positions. 
     FIG. 8 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which uses two blinds, the movement of one of which is directed by a cylindrical projection of the lock and the other of which is directed by the one blind, both blinds being locked in their terminal positions by a spring. 
     FIG. 8A is a section view taken along line A--A in FIG. 8 through the appraratus of FIG. 8. 
     FIG. 9 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which is rotated about a screw of the lock by a spring and locked in the rotated position. 
     FIG. 10 is a plan schematic view of the side of the lock of FIG. 1 facing the door with the lock cover removed showing another embodiment of a protective device which locks the bolt of the lock by means of a disc with a tooth. 
     FIG. 11 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which locks the bolt of the lock by means of a pawl which is connected to a plate. 
     FIG. 12 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which locks a lever of the bolt mechanism to lock the bolt of the lock. 
     FIG. 13 is a plan schematic view of the side of the lock of FIG. 1 facing the door showing another embodiment of a protective device which obstructs the slot through which the connecting bar of the lock is inserted and also locks a lever which locks the bolt of the lock. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The protective device or apparatus of the invention is intended to obstruct the opening to the bolt mechanism of the lock when the cylinder and the connecting bar of the lock are destroyed, i.e., the connecting bar is removed from the opening to the bolt mechanism, thus preventing actuation of the lock by a screwdriver inserted into the bolt mechanism through the opening. The protective device is an independent device which is inserted into a standard lock without requiring changes to the lock. 
     The small free space "S" (FIG. 1) between a standard lock 1 and a door and between the lock and a backplate 2 used to fasten the lock cylinder to the door poses a problem to providing such a device because the free space is insufficient to accommodate any device having an accompanying case or housing. A similar problem arises if a protective device is to be inserted into the lock case or housing in which the bolt mechanism of the lock is disposed. Depending on where a protective device of the invention is placed, it can provide the following security. If it is placed between the lock and the door, then the protective device is able to obstruct the slot or opening of the lock through which the connecting bar of the lock is inserted. If the protective device completely or partially is placed into the lock housing, it is able to lock the bolt of the lock when the cylinder with its connecting bar are removed. 
     According to the invention, these problems are solved by using the walls 3 of the lock body or housing, the lock screws 4, and/or the projection 5 or other rigid parts of that lock without otherwise fastening the device to the lock. The protective device is realized by parts whose movement, and initial and terminal positions, are determined by means of the lock housing walls, the lock screws and other parts of a standard lock to which a protective device is mounted. Different embodiments of protective devices are described below. 
     FIG. 2 shows an embodiment of a protective device in which the blind or plate-like element 6 together with a spring 7, which is fastened to the blind, is inserted into the free space "S" (FIG. 1) between the lock 1 and the door. The blind 6 is urged against the connecting bar 8 of the lock by the spring 7. One of the screws 4 of the lock passes through the coil 9 of the spring 7. When the cylinder together with the connecting bar are removed, then the blind 6 urged by means of the spring 7 pivots to block the slot or opening through which the connecting bar 8 enters into the housing, thus preventing a screwdriver from being inserted into the slot which could otherwise be used to unlock the lock. A flat spring 10 fastened to the blind engages the projection 5 of the lock and locks the blind 6 in its rotated, terminal position, making it impossible to move the blind 6 by a sharp tool in an attempt to open the slot of the lock. 
     FIG. 3 shows an embodiment of a similar protective device in which a screw of the lock passes through a hole of the blind. Similar parts in FIGS. 2 and 3 are marked with the same numbers. Locking of the blind 6 in its terminal position in FIG. 3 is accomplished by the free end of the spring 7 which engages the housing when the blind is in its terminal position shown in broken lines. 
     FIG. 4 shows an embodiment of a protective device in which the blind 11 is provided with a variable lift cam 12 which is rotatably fastened to the blind by the axle 13 and rotatable about the axle under action of a spring 14 engaging the blind and the cam. In the initial position of the blind 11, a recess 15 of the blind engages the connecting bar 8 urged by the cam 12 which is engaged against the wall 3 of the lock housing. When the bar 8 is removed, the blind permits the cam 12 to pivot on the axle 13 under action of the spring and the cam pushes the blind 11 sidewards to block the slot of the lock from which the bar 8 extended. The shape of the housing of the lock and the positions of its screws 4 determine the terminal position of the blind. The blind is locked in its terminal position by means of the cam 12, which engages the wall 3 of the lock housing at a right angle. The contours of the blind 11 are such that they permit movement of the blind from its initial position to its terminal position. 
     FIG. 5 shows an embodiment of a protective device in which the blind 16 is provided with a hole 17, through which one of the screws 4 of the lock passes. The blind 16 is also provided with a variable lift cam 18 rotatably fastened to the blind by axle 20 which is rotated by means of an Archimedean spiral spring 19 wound around an axle which is fastened to the blind. In the initial position of the blind, a recess of the blind 16 is urged against the connecting bar 8 and the cam 18 is pressed against the wall 3 of the lock housing by the spring 19 which engages the cam. When the bar 8 is removed, the blind 16 permits the cam 18 to rotate under action of the spring around its axle 20 and the cam in turn rotates the blind 16 about the screw 4. In the terminal position, the blind 16 blocks the slot from which the bar 8 has been removed. Another screw (unreferenced) of the lock determines the terminal position of the blind 16. The cam 18 locks the blind in the terminal position because the cam extends at a right angle relative to the wall 3 of the lock housing. 
     FIG. 6 shows an embodiment of a protective device in which the blind 22 is provided with a hole through which the connecting bar 8 passes. When the bar 8 is removed, the blind by means of the spring 23 fastened to the blind and engaging the wall of the lock housing is moved sidewards and is urged against the wall of the lock housing. As a result, the blind 22 obstructs the slot through which the connecting bar was inserted. The movement of the blind is directed by means of its bent edges 24 (FIG. 6A), which slide on the projection 5 of the lock. In its terminal position, the blind is locked by means of a flat spring 25, which is fastened with one of its ends on the blind and the other of its ends engaged by the projection 5. 
     FIG. 7 shows an embodiment of the protective device in which two blinds 26 and 27 are used, which are connected by a spring 28 respective legs 29 and 30 of which are fastened to a respective blind. A screw 4 of the lock is inserted through the coil of the spring. The protective device is inserted into the lock so that the connecting bar 8 engages respective recesses 31 and 32 of the blinds. When the connecting bar is removed, both blinds are rotated around the screw 4 in opposite directions and are placed in the terminal positions shown in the FIG. 7 obstructing the slot to prevent insertion of the connecting bar. The blinds are locked in their terminal positions by a tooth 33 on the blind 27 which engages the blind 26. 
     FIG. 8 shows an embodiment of the protective device in which two blinds 34 and 35 are used which are connected by means of a spring 36. One end of the spring is free to move into engagement with lug 37 of the blind 35, and the other end of the spring is inserted into the lug 38 of the blind 34. The protective device is inserted into the lock so that the connecting bar 8 passes through the hole in the blind 35 and is engaged by the recess 39 of the blind 34. When the connecting bar is removed, the spring 36 pushes both blinds in opposite directions and they both obstruct the slot to prevent insertion of any tool. When the blind 34 is moved, it is directed by means of its bent edges (FIG. 8A) which slide on the projection 5 of the lock, and the blind 35 slides on the bent edges of the blind 34. In its terminal position, the blind 34 is urged against the wall 3 of the lock housing and is locked in this position by a flat spring 40, which engages a tooth 41 on the blind 35. FIG. 8 shows the initial position of the blinds, which are urged against the connecting bar 8. 
     FIG. 9 shows an embodiment of the protective device in which a blind 42 is provided with a hole 43 and an Archimedean spiral spring 44 fastened to the blind. In the initial position, which is shown in solid lines, the blind is inserted into the lock so that the lock screw 4 passes through the hole 43 and the blind 42 is urged against the connecting bar 8 of the lock by the spring 44 which is engaged by the wall 3 of the lock housing. When the connecting bar is removed, the spring 44 straightens and pushes the blind to its terminal position shown in dotted lines, in which the blind obstructs the slot and prevents the insertion of any tool into the lock. In this terminal position, the blind is locked by the spring 44 because it extends at a right angle to and is engaged by the wall 3 of the housing. 
     FIG. 10 shows an embodiment of protective device which locks the bolt of the lock when the connecting bar is removed. This protective device is placed into the housing of the lock where the mechanism of the bolt of the lock is disposed. The post 45 of the lock is used as an axle for the disc 46 which is provided with a tooth 47 which engages the bolt 48 of the lock to lock the bolt in place. This disc is placed on the cam 49 of the button of the lock between the cam and the cover of the lock housing, the cam 49 moving the bolt 48 when the connecting bar 8 is rotated. A spring 50 which is fastened on the disc 46 urges the disc against the connecting bar 8 of the lock, which is inserted through a hole in the disc. A spring 51 locks the disc when it is rotated around the axle 45 upon removal of the connecting bar. 
     FIG. 11 shows another embodiment of a protective device for locking the bolt of the lock in which a lever 52 is placed into the lock housing in which the mechanism of the bolt of the lock is disposed rotatable about the lock screw 4. The lever 52 includes a lever arm 53 which acts as a pawl and locks the bolt of the lock when the lever 52 is rotated about the screw 4 to its terminal position, which is shown in dotted lines. A second arm of the lever is bent and provided with a tooth 54 which is inserted through a hole in the cover of the lock so that it projects into the space between the cover of the lock and the door. The second arm interacts with a plate 55 disposed in the space between the cover and the door which is also rotatable about the screw 4 and is provided with a hole 56 through which the connecting bar 8 of the lock is inserted. When the connecting bar is removed, the spring 57, which is fastened to the plate 55, pushes the plate 55 sidewards so that the projection 53 of the plate 55 engages the tooth 54 of the lever 52. As a result, the lever 52 is also rotated around the screw 4 and its lever arm 53 locks the bolt 48 of the lock. 
     FIG. 12 shows another embodiment of the protective device which is placed between the lock and the door for locking the bolt of the lock. The plate 59 of the device is provided with a hole through which the screw 4 of the lock passes and about which the plate is rotatable. A hole 60 is provided in the plate through which the connecting bar 8 of the lock passes. When the connecting bar is removed, the plate 59 is pushed sidewards by spring 61. A tooth 62 on the plate 59 is inserted through a hole in the cover of the lock and moves in the direction of the arrow to the lower terminal position to lock the lever 63 and thereby lock the bolt 48 of the lock. The flat spring 64 which is fastened on the plate 59 is pressed against the door and pushes the plate 59 with its tooth 62 into the housing of the lock to lock the lever 63 and the bolt 48 of the lock. 
     FIG. 13 shows an embodiment of a protective device which both obstructs the slot through which the connecting bar passes into the lock and locks the bolt of the lock when the connecting bar is removed. In addition, the device switches on sound apparatus having a dog's bark recorded for frightening a would-be intruder. This embodiment is the same as that in FIG. 5 except that the blind 65 is provided with a tooth 66 which is bent and passes through a hole in the cover of the lock. The blind is placed so that the tooth extends into the housing in which the mechanism of the bolt is disposed. Rotation of the blind 65 around the screw 4, when the connecting bar is removed, causes the bolt 48 of the lock to be locked by the lever 63, and by means of a contact 67, switching on of the sound apparatus. The blind 65 upon being pivoted obstructs the hole through which the connecting bar extended.