Tumbler lock-key-assembly

Abstract: A combination of a disc tumbler lock and a key (8) therefor provided with key-bit means (8b, 8c), the lock including a lock case (1) having therein a lock bolt (3) movable back and forth and provided with a locking pin (4) or the like and a set of tumbler discs (5) movable by turning the key and which are provided with a locking channel arranged to co-operate with the locking pin (4) to control the transfer movements of the lock bolt (3). The locking channel has at least a first (5a) and a second (5b) branch extending transversely relative to the transfer movement of the lock bolt and a third branch (5c) connecting the first and second branches, whereby the key-bit means (8b) of the key has for each tumbler disc a combination surface (8c) which, when the key is turned in the lock, moves the tumbler disc (5) in the direction of the first (5a) and second (5b) branch to select the locking combination. The key-bit means (8b) contains a guide member (8d) which affects the lock bolt (3) so that, in the final stage of the selecting movement of the tumbler disc (5), it guides the locking pin (4) into the third branch (5c) of the locking channel. The third branch (5c) of the locking channel also has at least one guiding means (5f,5g) which is arranged to prevent movement of the locking pin (4) through the third channel (5c) if the combination surface of the key is incorrect.

Description: This invention relates to a combination of a disc tumbler lock and a key therefor, the combination being in accordance with the preamble of ensuing claim 1. A lock and key combination similar to the preamble of claim 1 is disclosed in DE-B-1159306. The invention also relates to the key of the combination and a key blank from which such a key is formed. Disc tumbler locks are often used as security locks in doors. While the market is expanding, there is a requirement for there to be a large number of possible different key alternatives for operating such locks. In principle this can be achieved, for example, by increasing the number of tumbler discs in the lock, by increasing the stepping alternatives for combination surface millings or by increasing the number of combination values. However, both the size of the key and the lock must be kept reasonable. Furthermore, decreasing the stepping of milling for its part can cause malfunctions and error openings. It is also desirable to make the picking of such locks as difficult as possible. Traditionally the locking channel of the tumbler discs used in these locks has locking branches and a straight connecting branch which extends in the direction of transfer movements of the lock bolt. In such cases it is sufficient to pick the lock for the tumbler discs to be arranged so that the connecting branches in their locking channels are located at the position of the locking pin. The lock bolt can then be pressed to its opening position while the locking pin moves directly through the branch of the locking channel in question. In order to prevent picking, it is known to provide the locking branches of the locking channel with different recesses in which the locking pin can be received whilst the correct positions of the tumbler discs are found. Thus probing of the position of the tumbler discs becomes more difficult. An aim of the invention is to provide a new combination of a disc tumbler lock and a key therefor which allows the use of a great number of new key alternatives and which makes it easier to prevent or deter picking of the lock. According to one aspect of the present invention there is provided a combination of a disc tumbler lock and a key therefor, the combination being as claimed in the ensuing claim 1. The key-bit means includes guide means which affect the lock bolt so that, in the final stage of the selecting movement of the tumbler disc, it guides the locking pin into the third branch of the locking channel. The third branch of the locking channel has at least one guiding means for guiding the locking pin at the same time as the transfer movement of the lock bolt and the selecting movement of the tumbler discs are achieved. The movement of the locking pin into the branch which interconnects the locking branches of the locking channel and, in this branch at least, at an early stage of the movement of the locking pin requires simultaneous movement of the tumbler disc. Thus in this case the traditional way of picking a lock, by alternately arranging individual tumbler discs of the lock, does not work. With the present invention, it is also possible to make the keys of corresponding old lock systems functionally incompatible, since these keys operate firstly by selecting the movement of the tumbler discs and only thereafter by the transfer movement of the lock bolt and its locking pin. Thus totally new key combination alternatives can be utilized. In practise the third branch of the locking channel advantageously has a guide surface which is angled or bevelled with regard to the transfer movement of the lock bolt and is arranged to co-operate with the locking pin. In addition the third branch of the locking channel is provided with a protrusion which limits or partially obstructs the width of the channel and which is arranged on the opposite side of the channel to the angled or bevelled guide surface and which, together with this guide surface, affects the locking pin and guides it in the direction of the selecting movement of the tumbler disc. Although it would be possible to transfer the locking pin to the third branch of the locking channels of all the tumbler discs, the protrusion prevents the transfer of the locking pin forward in the branch in question unless also all tumbler discs are simultaneously moved correctly. Different key combinations can advantageously be accomplished by varying the shape and/or the size of the guiding means of the third branch of the locking channel of the tumbler disc. In this case the corresponding shapes of the combination surfaces of the key can be changed correspondingly so that combination surfaces of a certain shape accomplish the functional compatibility of the locking pin only with a locking channel provided with guiding means having a certain shape and/or size. The locking channel may, in a known way, be provided with a fourth branch, which extends transversally with respect to the transfer movement of the lock bolt, and a fifth branch, which connects the second and fourth branches. In this case the fifth branch is also conveniently provided with guiding means for guiding the locking pin. As a consequence, in order to open the lock, two successive selecting movements, caused by turning the key, are required, which increases the number of alternative combinations and improves the possibilities of preventing picking of the lock. In practise a locking pin compatible with the above-mentioned restriction members and guide surfaces can with advantage be obtained if the cross-section of the locking pin taken in the direction of the selecting movement of the tumbler disc is triangular. Suitably the key has an elongate shank and the key-bit means extend in an axial plane containing the elongate axis of the shank and are formed with said combination surfaces, the guide means extending outwardly, perpendicular to the axial plane, further than the key-bit means and are arranged to move the lock bolt and thus the locking pin before finishing the selecting movement of the tumbler discs of the lock. The combination surfaces accomplishing the selecting movement of the tumbler discs are arranged on the key blade on both sides of the guide member in the axial direction of the shank of the key. If there are equal numbers of combination surfaces on both sides of the guide means, the key can advantageously be operated from both sides of the lock. The key-bit means may also include a guide surface independent of the guide means to provide the transfer movements of the lock bolt after the selecting movement of the locking combination. The guide surface and the guide means are suitably arranged in the same cross-sectional plane with regard to the shank of the key. The number of locking combinations available can essentially be increased by having at least two different combination surface types which can be used. These combination surface alternatives can be arranged to be functionally incompatible with the tumbler disc of the other alternative(s) since the compatibility with the tumbler disc requires only that certain changes required by each combination surface type are made to the locking channel of the tumbler disc. The combination surfaces of the key can then be selected to contain either one of the combination surface types or any combination thereof. The combination surface types can advantageously include a plane surface milling and a milling surface comprising two bevelled or angled surfaces which taper or converge towards the tip part of the blade. In practise the blade of the key most preferably has at least one such combination surface that contains a tip formed by opposite bezels in perpendicular cross-sectional level of the shank of the key. Mixed use of different combination types complicates essentially remembering the combination values of the key and thus unauthorised manufacturing of the key. The number of combination alternatives is further increased as the key has two blade parts provided with combination surfaces and positioned symmetrically on both sides of the shank of the key blank. The combination surfaces of the blade parts can mutually be at least partly different either as regards the value of millings or the type of the combination surface. According to another aspect of the present invention there is provided a key blank as claimed in the ensuing claim 13. The guide means is arranged to move the lock bolt of the lock, and thus also the locking pin, before finishing the selecting movement of the tumbler discs of the lock. According to a further aspect of the present invention there is provided a key as claimed in the ensuing claim 17. Embodiments of the invention will now be described, by way of example only, with particular reference to the accompanying drawings, in which: Figs. 1 - 6 show a lock of a lock and key combination according to the invention, the lock being shown in different operational positions viewed from one side and with an opened cover of the lock casing; Fig. 7a shows an enlarged view of a tumbler disc of the lock with its locking channels; Fig. 7b shows schematically the movement of a locking pin in the locking channel of the tumbler disc of Fig. 7a in different operational positions of the lock; Fig. 8 shows different combination milling alternatives for the key of the lock; and Fig. 9 is a sectional view taken on line IX-IX of Fig. 8. In the drawings reference numeral 1 designates a lock casing of a lock for installation on a door or the like and includes a front plate 2 and a lock bolt 3 movable back and forth on operation of a key 8 of the lock between a protruding locked position and a retracted released position. The lock casing 1 preferably has a keyhole 1b at each of its two sides. The key 8 (see Fig. 8) includes a shank 8a having two key-bits in the form of blade parts 8b1 and 8b2. The lock casing 1 houses a set of tumbler discs 5 which are separated from each other by spacer plates 7 and which each have a multi-branched locking channel for a locking pin 4 of the lock bolt 3. In order to control the movements of the locking pin 4, and thus of the lock bolt 3, the lock has a guide groove 1a. As is more apparent from Fig. 7a, the locking channel is provided, in the embodiment shown, with locking branches 5a, 5b and 5d which are interconnected by branches 5c and 5e. When the locking pin 4 moves through the branches 5c or 5e, the lock bolt 3 moves simultaneously from one position to another. The branch 5c has an inclined guide surface 5f and a guide protrusion 5g. Correspondingly the branch 5e has an inclined guide surface 5i and a guide protrusion 5h. These guide surfaces and guide protrusions guide the relative movement of the locking pin 4 along the locking channel as shown in Fig. 7b. In practice, because of the guide groove 1a, the movement of the lock bolt 3 and the locking pin 4 is linear, so the transfer of the lock bolt 3 requires correspondingly movements of the tumbler disc 5. The locking channel can also be provided with recesses 5j which, together with a recess 4a of the locking pin 4, make it more difficult to probe the position of the tumbler discs and thus to pick the lock. As is more apparent from Figs. 8 and 9, there are combination surfaces 8c (8c1, 8c2 etc.) on the key 8 for each tumbler disc 5 and correspondingly the tumbler discs 5 have counter surfaces 5k for the combination surfaces of the key. When the key 8 is turned in the lock to select the locking combination, the tumbler discs 5 move upwards (as viewed in Figs. 1 to 6) guided by pins 9a and 9b of the lock casing against the force of springs 6. The combination surfaces are formed by milling the key-bits of the key. In the embodiment shown, the key 8 has two key-bits or blade parts 8b1 and 8b2. These together with the three locking branches 5a, 5b and 5d of the locking channel provide two protruding positions of different length for the lock bolt 3, which can be obtained with two consecutive selecting movements of the tumbler discs 5 caused by turning the key 8. Referring to Figs. 1, 8 and 9, the blade parts 8b1 and 8b2 of the key are additionally equipped with guide members 8d (8d11 etc.), which act on the guide surfaces 3a1, 3a2, 3b1 and 3b2 of the lock bolt 3 to transfer the lock bolt 3 at the final stage of each selecting movement of the tumbler discs 5 so that the locking pin 4 is guided to the branch 5c of the locking channel or correspondingly to the branch 5e. Furthermore, the blade parts of the key have guide surfaces 8e1 and 8e2 to provide the actual transfer movements of the lock bolt 3 after the selecting movement of the locking combination. For this there are guide surfaces 3a3 and 3b3 in the lock bolt 3. The operation of the lock is as follows. In the starting situation of Fig. 1, the lock bolt 3 is in its outer protruding position, whereby the locking pin 4 is in the locking branch 5a of the locking channel of the tumbler discs 5. When the key 8 is turned in the lock, the combination surface series 8c1 hits the stop surface 5k of the tumbler discs, whereupon the tumbler discs 5 move upwards (as viewed in Figs. 1-6) against the force of the springs 6. At the same time the relative position of the locking pin 4 in the locking branch 5a changes. After this, in the final stage of the selecting movement of the tumbler discs 5, the guide protrusion 8d12 in the key hits the guide surface 3a1 of the lock bolt and starts to move the lock bolt 3 to the right (as viewed in Fig. 2) concurrently as the tumbler discs 5 are moved as a result of being displaced by the combination surfaces of the key. As a result of the combination of these movements, the locking pin 4 is first guided to the branch 5c of the locking channel and from there further onward until the selecting movement of the tumbler discs is finished, assuming that the analogous combination surfaces of the key are correct. Then, in the situation of Fig. 3, the guide surface 8e1 of the key affects the stop surface 3a3 of the lock bolt and moves the lock bolt forward at the same time as the locking pin 4 moves in the branch 5c below the guide protrusion 5g. The transfer of the locking pin 4 through the branch 5c, however, succeeds only with the help of the correct combination of the above-mentioned movements. For example, if the selecting movement of the tumbler discs had already been finished, the guide protrusion 5g would prevent the moving of the locking pin 4 in the branch 5c of the locking channel. Correspondingly, the guide surface 5f prevents the transfer of the locking pin 4 in the branch 5c of the locking channel in case the corresponding combination surface of the tumbler disc 5 is incorrect either regarding its combination value or its combination surface type. In the situation of Fig. 4, the locking pin 4 has already moved to the position of the locking branch 5b of the locking channel. In this case the tumbler discs 5 are moved downwards (as viewed in Fig. 4) pressed by the spring 6 at the same time as their guide surfaces 5k and combination surfaces 8c1 still remain in contact with each other. In this stage the guide member 8d11 on the other side of the blade 8b1 of the key acts on the guide surface 3a2 of the lock bolt and the guide surface 8e1 of the key correspondingly acts on the guide surface 3a1 of the lock bolt so that they together guide the locking pin 4 past the picking recess 5j located in the locking branch 5b of the locking channel. As a result of this, on turning the key 8 further, the locking pin 4 is able to move to the end of the locking branch 5b as is apparent from Fig. 5. The transfer of the lock bolt 3 and the locking pin 4 from the position of Fig. 5 to the position of Fig. 6, where the lock bolt is totally retracted and the key is removed from the lock, occurs in a totally analogous way as described above by turning the key 8 further in the same direction. Correspondingly, when the lock bolt 3 is transferred back to the protruding position the above described measures occur in the reverse order. As particularly can be noticed from Figs. 7a and 7b, the guide surfaces 5f and 5i of the locking channel and the guide protrusions 5g and 5h differ somewhat from each other. Correspondingly the combination values of the combination surfaces 8c121 and 8c232 of the opposite blade parts of the key of the Figs. 1-5, but in addition particularly the shapes of the surfaces differ from each other (cf. Fig. 9). In this way two different shapes of combination surfaces can be utilized as combination surfaces of the key for each combination value, the compatibility of which with the locking channel of the tumbler disc is determined expressly by the shape and location of the above mentioned guide surfaces and guide protrusions and, when necessary, in addition by the exact location of the transversal branch 5c or 5e so that a particular shape of the combination surface is compatible with only a certain type of guide surface shape and the guide protrusion. This is based on the fact that the disclosed combination surface types differing from each other provide movements at the final stage of the selecting movement which differ slightly from each other. Different combination surface alternatives are presented schematically in Figs. 8 and 9. Since in the embodiment disclosed two different selections of tumbler discs are accomplished by means of two blades 8b1 and 8b2 of the key, one for each protruding length of the lock bolt, hereby an enormous number of different locking combinations can be obtained for utilization. For example assuming that the lock is a symmetrical lock, whereby the key can be inserted in the lock from either side, and that there are two key blade parts in the key located opposite to each other and having combination surfaces for eight tumbler discs, whereby four different combination values can be provided for each combination surface, which for their part can be provided with two different shapes of the combination surface, one gets theoretically 16777216 different locking combinations. Of these it is possible to apply in practice at least 1005480 combinations. In the case of an asymmetric lock, one ends up correspondingly with substantially larger amounts. The invention is not limited to the shown embodiments, but several modifications are feasible within the scope of the invention as defined by the attached claims.

Claims: A combination of a disc tumbler lock and a key (8) therefor provided with key-bit means (8b, 8c), the lock including a lock case (1) and, mounted within the lock case, a lock bolt (3) movable between locking and releasing positions and provided with locking pin means (4), and tumbler discs (5) movable by the key on turning of the latter within the lock, each tumbler disc being provided with a locking channel co-operable with said locking pin means (4) to control the movement of the lock bolt (3) between its locking and releasing positions, each locking channel having at least first and second branch portions (5a and 5b) extending transversely to the directions of movement of the lock bolt between its locking and releasing positions and a third branch portion (5c) connecting said first and second branch portions (5a and 5b), whereby said key-bit means (8b, 8c) has, associated with each tumbler disc (5), a separate combination surface (8c) which, when the key is turned in the lock, moves the tumbler disc (5) in the direction of said first and second branch portions (5a and 5b) to select the locking combination, characterised in that said key-bit means (8b, 8c) further has guide means (8d) which coacts with the lock bolt (3) so that, during a final stage of the selecting movement of the tumbler disc (5), it guides the locking pin (4) into the said third branch portion (5c) of the locking channel, and in that the said third branch portion (5c) of the locking channel has a protrusion (5g) limiting the width of the locking channel so that it prevents the locking pin (4) from moving along said third channel portion (5c) if the combination surface of the key is incorrect. A combination according to claim 1, characterised in that said third branch portion (5c) of the locking channel has a guide surface (5f) angled with regard to the direction of movement of the lock bolt between the locking and releasing positions of the latter and arranged to co-operate with the locking pin means (4). A combination according to claim 2, characterised in that said angled guide surface (5f) is arranged on the opposite side of the locking channel to said protrusion (5g), said protrusion (5g) and said guide surface (5f) cooperating with the locking pin (4) to control the relative movement of the latter along the locking channel. A combination according to any one of the preceding claims, characterised in that the shape and/or size of said guide surface (5f) and/or said protrusion (5g) of the different locking channels are not all the same, and that the shapes of the corresponding combination surfaces (8c) of the key are arranged so that a combination surface (8c) with a certain shape accomplishes the functional compatibility of the locking pin (4) only with a locking channel (5c) provided with a guide surface and protrusion having the correct shape and/or size. A combination according to claim 3 or 4, characterised in that each locking channel has a fourth branch portion (5d) extending transversely to the directions of movement of the lock bolt between its locking and releasing positions and a fifth branch portion (5e) connecting said second and fourth branch portions (5b and 5d), and in that said fifth branch portion also has an angled surface (5h) and an oppositely positioned projection (5i) for controlling relative movement of the locking pin means (4) along the locking channel. A combination according to any one of the preceding claims, characterised in that the cross-section of the locking pin means (4) taken in the direction of the selecting movement of the tumbler discs (5) is triangular. A combination according to any one of the preceding claims, characterised in that said key has an elongate shank (8a) and said key-bit means (8b) extend in an axial plane containing the elongate axis of the shank and formed with said combination surfaces (8c), in that the said guide means (8d) extend outwardly, perpendicular to said axial plane, further than said key-bit means (8b), and in that the combination surfaces (8c) are formed on either side of the guide means (8d) in the direction of said elongate axis. A combination according to claim 7, characterised in that the key-bit means (8b) includes a guide surface (8e) separate from said guide means (8d) for providing the transfer movements of the lock bolt (3) after the selecting movement of the locking combination, and in that said guide surface (8e) and said guide means (8d) are arranged in the same plane perpendicular to the elongate axis of the shank (8a). A combination according to claim 7 or 8, characterised in that the combination surfaces (8c) for moving the individual tumbler discs (5) can alternatively be selected from at least two different combination surface types, the shapes of which differ from each other and which are arranged to be functionally incompatible with a tumbler disc (5) according to the other alternative, and in that the combination surfaces (8c) of the key are selected to contain either one of said combination surface types or any combinations thereof. A combination according to claim 9, characterised in that the said combination surface types include a plane surface milling (8c111 etc.) and a milled surface (8c112 etc.) comprising two adjacent bezels tapering to the tip part of the key-bit means. A combination according to claim 9 or 10, characterised in that the key-bit means (8b) has at least one combination surface (8c) that contains a tip (8c112 etc.) formed by opposite bezels in perpendicular cross-sectional plane of the shank (8a) of the key. A combination according to any one of claims 10 to 14, characterised in that it contains two key-bit means (8b1 ,8b2) provided with combination surfaces and located symmetrically on both sides of the shank (8a) of the key blank, and in that the combination surfaces (8c1,8c2) of the blade parts (8b1,8b2) are mutually at least partly different either as regards the value of millings or the type of the combination surface. A key blank which can be milled to form the key of a combination according to any one of the preceding claims, the key blank comprising an elongate shank (8a), two blade parts (8b1,8b2) on opposite sides of the shank and extending in an axial plane containing the elongate axis of the shank and intended to be milled to form the combination surfaces (8c) of the key which, in use of the key in the lock, turn the tumbler discs (5) of the lock, characterised in that said blade parts (8b1,8b2) are located symmetrically on opposite sides of the shank and in that the key blank further comprises guide means (8d11,8d12,8d21,8d22) intended, in use of a key formed from the key blank, to coact with the lock bolt (3) of a lock, the guide means extending outwardly, in directions perpendicular to said axial plane, from surfaces of each of the two blade parts (8b1,8b2) positioned on opposite sides of said axial plane, the guide means on opposite sides of said axial plane being symmetrical with each other. A key blank according to claim 13, characterised in that each of said guide means (8d11,8d12,8d21,8d22) has an axial extent less than the axial extent of the blade part (8b1,8b2) from which it extends. A key blank according to claim 13 or 14, characterised in that each of said guide means (8d11,8d12,8d21,8d22) is positioned, in the axial direction, in a central part of the blade part (8b1,8b2) from which it extends. A key blank according to claim 13, 14 or 15, characterised in that each of said guide means (8d11,8d12,8d21,8d22) is positioned radially inwardly of the radially outer extremity of the blade part (8b1,8b2) from which it extends. A key for operating a disc tumbler lock including a lock case (1) and, mounted within the lock case, a lock bolt (3) movable between locking and releasing positions and provided with locking pin means (4), and tumbler discs (5) intended to be operated by the key on turning of the latter within the lock, each tumbler disc being provided with a locking channel co-operable with said locking pin means (4) to control the movement of the lock bolt (3) between its locking and releasing positions, each locking channel having at least first and second branch portions (5a and 5b) extending transversely to the directions of movement of the lock bolt between its locking and releasing positions and a third branch portion (5c) connecting said first and second branch portions (5a and 5b) and having a protrusion (5g) limiting the width of the locking channel, the key comprising an elongate shank (8a), two blade parts (8b1,8b2) on opposite sides of the shank (8a) and extending in an axial plane containing the elongate axis of the shank, each blade part having, associated with each tumbler disc (5), a separate combination surface (8c) which, when the key is turned in the lock, is intended to move the tumbler discs (5) in the direction of said first and second branch portions (5a and 5b) to select the locking combination, characterised in that said blade parts (8b1, 8b2) are located symmetrically on opposite sides of the shank (8a) and in that each of said blade parts has guide means (8d11,8d12,8d21,8d22) extending outwardly on opposite sides of, and in directions perpendicular to, said axial plane, said guide means on opposite sides of said axial plane being symmetrical with each other and being intended in use to coact with the lock bolt (3) so that, during a final stage of the selecting movement of the tumbler discs (5), they guide the locking pin (4) into the said third branch portion (5c) of the locking channel. A key according to claim 17, characterised in that each of said guide means (8d11,8d12,8d21,8d22) has an axial extent less than the axial extent of the blade part (8b1,8b2) from which it extends. A key according to claim 17 or 18, characterised in that each of said guide means (8d11,8d12,8d21,8d22) is positioned, in the axial direction, in a central part of the blade part (8b1,8b2) from which it extends. A key according to claim 17, 18 or 19, characterised in that each of said guide means (8d11,8d12,8d21,8d22) is positioned radially inwardly of the radially outer extremity of the blade part (8b1,8b2) from which it extends.

Inventors: HAAPANIEMI JOUNI, LINDSTROEM MARKO, PIHLAJA OLLI, HAAPANIEMI, JOUNI, LINDSTROEM, MARKO, PIHLAJA, OLLI, Lindström, Marko
Applicants: BJOERKBODA LAS OY AB
Application year: 2000
Main classification: E05B21
IPC codes: E05B21, E05B19, E05B25