FIELD OF THE INVENTION

This invention relates to cylinder locks and keys.

BACKGROUND OF THE INVENTION

Figs. 1 and 2 show schematically a conventional cylinder lock 10, in the secured 5 (locked) and unsecured (open) positions, respectively. The lock 10 includes a housing 11 having a cylindrical bore in which is mounted a revolving cylinder 12 having a plurality of bores 13 each of which, in the secured position, is aligned with a respective bore 14 in the housing as shown in Fig. 1. Each of the bores 13 accommodates a respective pin 15 that is biased by a spring 16 within the corresponding bore 14 having

10 a head 17. In the secured position of the lock 10, the springs 16 urge the pins 15, which are of varying heights, so that they intersect the boundary between the respective bores 13 and 14, thereby preventing rotation of the cylinder 12 within the housing 11.

When a suitably coded key 18 shown in Fig. 3 is inserted into a key slot in the cylinder, indents or recesses or depressions 19 in the key push the pins 15 against the

15 spring bias. Each pin 15 is displaced by a different amount depending on the depth of the corresponding recess 19 in the key. The recesses 19 and the lengths of the pins 15 are matched so that when the key is inserted all the pins extend to the same level where their ends are aligned with the boundary between the corresponding bores 13 and 14. In this position, the pins 15 no longer obstruct the bores 14 in the housing and the cylinder

20 12 is thereby able to rotate with the housing. The revolving cylinder is mounted in a through bore of the housing, and the key slot which accepts the key extends substantially through the revolving cylinder. The pins are typically arranged along the axis of the cylinder and engage the key as the key is moved into the key slot. Cy Under locks may be mounted in conjunction with conventional mortise locks wherein a sprung latch engages a mortise formed in a door jamb. Alternatively, they may be used to rotate a toothed wheel that operates a central locking mechanism that moves a plurality of bolts into corresponding recesses formed in a reinforced door frame.

Although the principles of the cylinder lock shown in Figs. 1 and 2 are described with regard to a Yale® type key where the recesses are formed in an edge of the key as shown in Fig. 3, in fact cylinder locks are also known where the key has depressions in at least one of its side surfaces that engage the pins. The depressions are of different depths and the principle of operation is the same as described above. Typically, the pins and the depressions are of spherical cross-section, which renders them easily susceptible to lock picking. Specialized lock picking tools are available that are inserted into the key slot and are shaped to engage the pins and depress them, one at a time, until they clear the edge between the respective bores in the cylinder and housing. More rudimen- tary lock picks do the same thing and the Internet is abundant with "how to do it" guides that show how to pick locks. Practice locks having transparent casings are also available for self-instruction.

Theory notwithstanding, the most common way to breach a cylinder lock is simply to drill through the cylinder with a drill of sufficient diameter that allows the locking pins to be dislodged after which the cylinder may be rotated manually. To this end, some manufacturers reinforce the cylinder with hardened steel inserts, but they can still be drilled and fractured with high quality high speed steel twist drills. Of course, this makes a lot of noise and may arouse suspicion: but this does not detract from the basic insecurity of the lock.

Another issue related to this type of lock is duplication of the key. Common

"Yale" type locks are easily duplicated using a cutter of fairly low cost. But higher-end locks such as manufactured by Mul-T-Lock Technologies Ltd., Yavne, Israel, which use keys having depressions formed in the side surfaces of the key, require more sophisticated machinery. Mul-T-Lock is a registered trademark of Mul-T-Lock Ltd. Additional security may be provided in order to prevent unauthorized copying such as supplying the certified owner with a smart card that is uniquely encoded and without which an authorized dealer will not be willing to copy the key. Furthermore, there may be no single machine may that is able to cut all keys. Instead, the key blanks are encoded and only machines that are suitable for use with the thus-identified key blanks may be suitable. This requires the owner to locate an authorized dealer who has the correct duplication machinery. It also means that the machinery is expensive, requiring a locksmith to make a very high capital investment in order to be able to offer key duplication; and even then a single machine may not be suitable for all key blanks. This is good business for the large manufacturers, but it impedes competition. Furthermore, although key blanks are not expensive, duplication of this type of key is much costlier than simple "Yale" type locks, not because the blanks are so much more expensive but because the locksmith has to recoup the capital investment of the much more expensive machinery.

Significant effort has been made to reinforce such locks and render them tamper-proof.

WO 2009/147677 discloses a lock having a housing formed with a cylindrical bore and a cylinder within said bore carrying locking elements movable to locking and unlocking positions with respect to said housing, characterized in that the cylinder carries at least one insert of a hard material configured, dimensioned and located such as to prevent pull-out of the cylinder from the housing by a pull-out force applied to the cylinder, and/or by drilling through the locking elements.

DE 4317994 discloses a lock cylinder, of which the cylinder plug rotatable in a plug-receiving bore of a housing contains reinforcing plates to provide protection against drilling open and destroying the thread of a plug-drawing screw possibly screwed into the keyway of the cylinder plug.

GB 2 298 454 discloses an anti-boring device for cylinder locks including a key channel and locking pins, with two reinforcement elements of hard material being arranged parallel or nearly parallel to the key channel extending through the bores of the cylinder core to both sides of the key channel. The device includes an additional shield arranged in a slot of the cylinder core within the area between the key channel and the joint face or extending beyond the joint face.

US 20070186600 discloses a lock cylinder assembly, which in one embodiment incorporates a hardened cylinder shield behind the front face of the cylinder blank to prevent drilling through the cylinder blank. US Patent No. 4,292,824 discloses a security lock in which a pin tumbler rotates in a cylinder housing composed of an axial stack of discs punched from a sheet of chrome-nickel steel and soldered or welded together to constitute a rigid element.

All of the locks so far described having a rotatable cylinder or drum having a key slot that accommodates the key and rotates when the key depresses a series of collinear pins that are aligned with the depressions in the key. However, another type of security lock comprises a coaxial stator and rotor and a series of radial locking pistons. The key for such a lock is not flat but is of generally polyhedral cross-section defining a number of surfaces around a generally cylindrical rod shaped for accommodation within complementary grooves in the stator and having indents shaped for engaging the pistons. Such a lock is described, for example, in FR 2 568 616 in the name of Thirard and a schematic sectional view thereof is shown in Fig. 4. Although it may appear from this drawing that the five pistons all lie in the same plane, in practice the lock includes a plurality of radially acting pistons along the axis of the cylinder. Since the heads of the pins are not aligned, this type of lock is difficult to pick.

In one particular lock of this type manufactured by Thirard and sold under the names Cobra and Axira, there is no rotor. Instead, a stator is supported on a bracket to which there is rotatably mounted a gear wheel that engages a locking mechanism in the door in known manner. A spring is resiliently mounted in a shaft of the key. The pistons prevent the key from rotating until the key is fully inserted into the stator against the resilient bias of the spring, when it displaces the pistons and allows the key to be rotated one or more full rotations, whereupon it is no longer retained and is urged out of the key slot by the spring bias. However, during the prior rotation of the key between its insertion and release, the end of the key engages the gear wheel, which thus rotates with the key and actuates the locking mechanism.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a more secure cylinder lock and key.

This object is realized in accordance with the invention by a cylinder lock, key and kit having the features of the respective independent claims.

According to one aspect of the invention there is provided a cylinder lock comprising a housing supporting a key slot and accommodating a plurality of resiliently displaceable pins which cooperate with the housing to enable or inhibit rotation of the key when inserted into the key slot so as thereby to align the pins with depressions formed in the key, said housing comprising at least two segments formed of mutually different materials at least one of which cannot be cut using high speed steel drill bits.

Commonly, the key slot is formed within a rotatable cylinder mounted in the housing and the pins cooperate with the housing and the cylinder to enable or inhibit the rotation of the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figs. 1 and 2 are schematic representations of a conventional cylinder lock in secure and open positions, respectively;

Fig. 3 is a schematic representation of a conventional key suitable for the lock shown in Figs. 1 and 2;

Fig. 4 is a schematic sectional view of a known cylinder lock having radially acting pins;

Fig. 5 shows an external perspective view of a cylinder lock according to an embodiment of the present invention;

Fig. 6 shows a detail of the cylinder lock with its outer casing removed;

Fig. 7 shows a sectional view of the lock through the plane A-A in Fig. 5;

Fig. 8a and 8b show pictorially details of a key suitable for the lock in Fig. 5 according to another aspect of the invention;

Figs. 9a and 9b show assembly of the key depicted in Figs. 8a and 8b; and

Figs. 10a, 10b, 10c and lOd show details of the key prior to assembly.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description of some embodiments, identical components that appear in more than one figure or that share similar functionality will be referenced by identical reference symbols. Figs. 5 to 7 show details of a cylinder lock 20 comprising a rotatable cylinder 21 mounted in a housing 22 and a plurality of pins 23 which cooperate with the housing and the cylinder to enable or inhibit the rotation of the cylinder. The housing 22 includes an aperture 24, which serves to secure the lock to a door jamb, after mounting 5 the lock in the door. The cylinder 21 has a key slot 25 for accommodating a key of the kind where the depressions are formed in a side surface, whereby insertion of a matching key (not shown) into the key slot 25 depresses each of the pins 23 against the resilient bias of corresponding springs 26 by just the right amount whereby the ends of all the pins become aligned with the boundary or "shear line" between the cylinder and

10 the housing. For the sake of completeness, there is shown a gear wheel 27 that is fixed at an inner end of the cylinder, so as to be rotated when the cylinder rotates. Such rotation engages the may operate a mechanism that pushes a series of reinforcement rods through different edges of the door so as to engage bores formed in corresponding edges of the door frame. All this is well-known per se.

15 One aspect of the invention resides in forming the cylinder 21 of at least two segments 28, 29, 30 (best seen in Fig. 7) of mutually different materials at least one of which cannot be cut using high speed steel drill bits. Suitable materials include bulletproof reinforced glass, titanium, concrete, reinforced steel and PCBN (polycrystalline cubic boron nitride). In Fig. 7 the segments are axially contiguous, but the invention

20 contemplates an arrangement where two non-contiguous segments 28 and 30 are formed of material that cannot be cut using high speed steel drill bits. In such an embodiment the middle segment 29 could be stainless steel although this is less preferable. The cylinder lock 20 shown in the figures has two coaxial outer and inner sections shown as 31 and 32, respectively and is often referred to in the trade as a "full cylinder". The lock

25 20 is mounted so that the outer section 31 faces outward i.e. to the outside of the building and it is in this section that the key slot 25 is formed in the cylinder 21. The inner section 32 faces inward i.e. to the inside of the building and also has a key slot for allowing the lock to be operated from inside the building using a suitable key. However, the inner section does not need to be reinforced. Alternatively, the lock may have only

30 an outer section and be operated from inside the building using a handle or thumbturn.

Such locks are often referred to in the trade as a "half cylinder". However, it should be pointed out for the sake of absolute clarity that the term "cylinder" as used throughout this application and appended claims relates only to the rotatable element. As just noted, many locksmiths refer to the complete lock assembly as the "cylinder" and refer to the hollow rotatable element with the key slot as a "drum". The distinction is important because although the invention certainly contemplates and indeed prefers forming both the cylinder and also the housing each of mutually different materials, at least one and preferably all of which require specialized cutting tools, it does not preclude reinforcing only the rotatable cylinder in this manner. This is because it is the rotatable cylinder that contains the key slot and it is typically via the key slot that most amateur attempts to break the cylinder and fracture the pins are made.

It is acknowledged that reinforcing only the cylinder 21 is not ideal because it is then possible to drill through the housing with a high speed steel drill bit and thereby shatter the pins. Once this is done, the cylinder 21 can be rotated without hindrance. Indeed, this is the approach generally adopted by professional locksmiths and intruders and much effort has therefore been expended to strengthen the housing in order to prevent this. To this end, a preferred embodiment reinforces both the cylinder 21 and the housing 22 as shown in Fig. 5 where the housing includes segments 35, 36 and 37 formed of mutually different materials at least one of which cannot be cut using high speed steel drill bits. Here also, preferably at least two axially contiguous reinforced segments 35, 36, 37 are provided, but the invention contemplates an arrangement where two non-contiguous segments 35 and 37 are formed of materials that cannot be cut using high speed steel drill bits, the intervening segment 36 being formed of stainless steel.

In the example shown in Figs. 5 and 7, both the housing 22 and the cylinder 21 have three reinforced segments. But the number of reinforced segments does not need to be the same in both components. Nor do they have to be formed of the same materials and even if both the housing 22 and the cylinder 21 have the same number of segments and for each segment 28, 29, 30 in the cylinder 21 there is a corresponding segment 35, 36, 37 in the housing formed of the same material, the matching segments in the housing 22 and the cylinder 21 do not need to be aligned. In practice, this means that is basically impossible to drill though either the cylinder or the housing without destroying the drill. In other words, breaching the lock by drilling through it is not feasible. Furthermore, the invention also contemplates locks built according to the principles of above-described FR 2 568 616 where a plurality of radially acting pins (or pistons) are disposed along the axis of the cylinder. In this arrangement, the pins are not collinear but the principle of operation is otherwise identical, the cylinder (referred to in FR 2 568 616 as the rotor) rotating within the housing (referred to as the stator). Either or both and preferably both of the cylinder and housing are reinforced according to the principles of the invention as described above. Likewise, the invention contemplates the type of lock described above sold by Thirard under the names Cobra and Axira where there is no rotor or cylinder. The housing of such a lock is also amenable to being reinforced according to the principles of the invention by forming it of two or more segments formed of mutually different materials at least one of which cannot be cut using high speed steel drill bits.

The invention exploits the fact that while common HSS drill bits are inexpensive and well within the arsenal of the average locksmith and intruders, high speed steel is not suitable for cutting through materials such as bullet-proof reinforced glass, titanium and concrete, which require specialized tools. The relative cost of these tools as compared with common HSS drill bit may be decisive in determining that no attempt is made to breach the cylinder since the cost of doing so is prohibitive. To put this in perspective, a drill bit suitable for cutting through bullet-proof reinforced glass that is of sufficient diameter to fracture the pins in a cylinder lock may cost several hundred dollars. It is altogether difficult to drill large holes of large diameter through titanium, even using cobalt or titanium-tipped drills, which have been proposed for small diameter holes using slow drill speeds and plenty of coolant. Furthermore, attempting to cut through these materials with the wrong type of drill bit will almost certainly result in destruction of the drill bit. From the outside of the building, it is not possible to see from what materials the cylinder or housing is formed and a locksmith will not want to take the risk that an expensive diamond tipped drill will be irrevocably damaged. This lack of certainty and the resultant security may be further enhanced by arranging the different materials in an unpredictable order, so that even someone who has gone to the trouble of taking one lock apart will be unable to assume that another lock contains the same materials or that the materials are arranged in the same order as the "practice" lock. Obviously, there is little merit in reinforcing the housing and cylinder if it is easy to pick the lock. To this end, the pins 23 may be polygonal in shape and oriented at different angles. This may be seen in Fig. 6 and even better in Fig. 8a showing a series of complementary key segments where they are shaped in the form of five -point stars, which are either not congruent or which may be congruent but oriented differently.

In this connection it will be understood that lock picking requires insertion of a uniform pick that tries to replicate the action of a key one pin at a time. To this end, the closest pin is first engaged by the pick and depressed until its end reaches the shear line between the cylinder and the housing, while applying a turning force to the cylinder which prevents the pin from springing back. The picking tool is then advanced to the next pin and in like manner all pins are moved until the cylinder may be freely rotated within the housing. Sometimes two tools are used: one to engage the pins and the other to apply a constant turning force to the cylinder. But in either case, only a single tool may be used to engage the pins and this implies that all the pins are of uniform shape. It is known in the art to make the heads of the pins bulbous in shape to deflect a picking tool and make it difficult to engage the pins. But this approach can be overcome using a suitably shaped lock pick of complementary shape to the pins.

The present invention overcomes these drawbacks because the pins are shaped and/or oriented to belie the possibility of engaging all the pins with a single pick. The pins 23 are of varying depths so as to be accommodated within complementary recesses formed in a surface of a generally flat key. The recesses in the key are shaped and dimensioned for accommodating the shaped surface face of a respective pin of the lock and are of a depth that when the key is inserted into the cylinder opposing planar surfaces of all of the pins are aligned with the shear line of the cylinder thereby allowing rotation of the cylinder within the housing.

Mention has been made above of the difficulty and expense of duplicating keys for high-end security locks. On the one hand, it is desirable to prevent duplication of the key from a mere inspection of the lock since this would facilitate unlawful entry. But on the other hand, it would certainly be desirable to facilitate duplication of the key for the lawful owner once he or she has presented suitable credentials attesting to his or her authenticity. Furthermore, it would be preferable to do this without the need for sophisticated machinery that requires significant capital outlay. Figs. 8 a to lOd show pictorially details of a key 40 according to another aspect of the invention that is ideally combined and employed in the lock described above with reference to Figs. 5 to 7 but may be used independently with other types of lock. The key 40 comprises a frame 41 for accommodating a plurality of axially mounted con- tiguous segments 42. Each segment 42 has a recess or depression 43 therein shaped and dimensioned for accommodating a first face of a respective pin 23 of the lock and is of a depth that when the key is inserted into the cylinder opposing second faces of all of the pins are aligned with the shear line of the cylinder thereby allowing rotation of the cylinder. In some embodiments each of the recesses 43 is of polygonal cross-section as shown in the figures. Each segment 42 has arcuate grooves 44 formed in opposing side edges each for engaging a complementary beveled inner edge of the frame 41, which thus provides opposing rails along which the segment 42 may slide easily but which prevent removal of the segments merely by pushing on a surface thereof. An edge of each segment is provided with a pair of outwardly protruding lugs 45 which engage corresponding sockets or grooves (not shown) formed in an abutting edge of an adjacent segment. When all the required segments are properly mounted in the frame 41 in correct order, an end-piece 46 also having arcuate recessed side surfaces is slid on to the open end of the frame to prevent the segments from becoming unintentionally dislodged and to support a handle 47 allowing the key 40 to be easily manipulated.

The security of the lock for use with the key 40 depends, inter alia, on the number of pins, which corresponds to the number of segments in the key since the more segments there are the greater is the number of combinations. This, in turn, determines the length of the frame required to accommodate the correct number of segments.

A locksmith need maintain only a kit comprising a plurality of frames 41 and a plurality of segments 42 adapted for support within the frames. All of the frames define groups, each containing frames of a characteristic length adapted to accommodate a predetermined number of segments. The segments also define groups, each containing segments having an identical recess of characteristic shape and depth. In order to replicate an encoded key, segments from specified groups are inserted into a specified frame type in a specified order. The frame type, segment types and the specified order are uniquely identified by an ID that uniquely identifies a lock with which the key is intended for use and which is associated with an authentic owner of the lock. The manner in which the locksmith determines the ID is not itself a feature of the invention but for the sake of completeness it may be encoded within the lock during manufacture in a manner that renders it readable only by authorized locksmiths. Alternatively, the ID may be encoded in a smart code that is given to the owner on purchase of the lock. It may be stored in a database to which authorized dealers and locksmiths have access and which maps a generic code stamped on the lock to a unique user ID, such as passport ID or driver's license and the like.

In this connection, it should be noted that attempts to force locks are not always indicative of unlawful behavior. Locksmiths are frequently called out to gain entry to premises where the lawful owner has lost or mislaid a key. Forced entry is almost always predicated on attempted drilling through the lock, which is rendered virtually impossible by preferred embodiments of the invention. As an alternative, the locksmith may have no recourse other than to cause irreparable damage to the door. The key 40 provides a very simple, effective and inexpensive solution to gaining authorized entry without forcing the lock as will now be explained.

Thus, not only does the key 40 avoid the need for expensive machinery to duplicate the key, but it also provides a highly effective way to assemble a key in situ and thereby gain entry to an authorized dealer without the need even to attempt forced entry. Let's consider the situation where the lawful owner has lost or mislaid a key. She calls out the locksmith who comes to her house with a kit as described above. The owner provides her ID to the locksmith who verifies it, typically on-line via using a smartphone or PDA against a database to which only authorized dealers or locksmiths have access and which stores the owner ID associated with all locks of a given manufacturer. The lock may bear an easily identifiable auxiliary code which on its own is insufficient to decode the lock, but which in combination with the user ID allows the authorized locksmith to determine the unique code of the lock in situ without damaging the lock. The unique code allows the locksmith to assemble the correct key in situ since it identifies each segment i.e. to which characteristic group each segment belongs and the order in which the segments must be assembled. The unique ID also informs him of the length of the frame since this determines the number of segments, which in turn must match the number of pins in the lock. The key is thus assembled in situ without requiring expensive machinery and without compromising the security of the lock, allowing the locksmith to gain entry quickly with no damage to the door or the lock.

It will be appreciated that modifications may be made without departing from the scope of the invention as defined by the claims. For example, while the invention has been described with particular reference to locks of the kind manufactured by Mul- T-Lock Technologies Ltd. wherein the key has depression in a side surface, the basic inventive concept is not limited to the type of key. Specifically, forming the cylinder of different materials, at least one of which cannot be cut with an HSS drill may be applied to any cylinder lock including those suitable for use with conventional Yale keys where the key has a serrated edge. On the other hand, the additional features relating to the pins and the key are applicable only to those keys where the depressions are formed in a side surface rather than an edge of the key.

Likewise, in the described embodiments the pins and complementary depressions are polygonal in cross-section. A five -pointed star is shown by way of example, but clearly other shapes are suitable provided that the combined shape and orientation of the pins belie the use of a uniform picking tool.

It should also be noted that features that are described with reference to one or more embodiments are described by way of example rather than by way of limitation to those embodiments. Thus, unless stated otherwise or unless particular combinations are clearly inadmissible, optional features that are described with reference to only some embodiments are assumed to be likewise applicable to all other embodiments also.