Improvements to pin tumbler locks and keys therefor

Abstract: The invention relates to an improvement in a key-actuated pin tumbler lock (10) of the type having: a cylindrical core (12) rotatable in a lock housing (24) via a rotational path (30), a plurality of pin tumblers (14, 16) received in bores (22, 23) journalled in the core (12) and lock housing (24), each bore (22, 23) containing a set of pin tumblers comprising one core (14) and one housing pin (16), biassed towards the core (12), and having a a pin junction (20) therebetween, and a key slot (28) in the core (12), whereby insertion in the key slot (28) of a key (31) having thereon suitable bits is adapted to align the pin junctions (20) with the rotational path (30) of the core (12) in the lock housing (24), and to permit the core (12) to rotate within the housing (24). The improvement comprises a retaining mechanism (32, 34) adapted to bias at least one of the pin tumblers (14, 16) towards engagement with the rotational path (30) of the core (12), the mechanism (32, 34) being adapted to restrain rotation of the core (12) until release of the or each biassed pin tumbler (14, 16) upon insertion of a key (31) including, as well as the suitable bits, means (35) for disengaging the retaining mechanism (32, 34) from engagement with the or each biassed pin tumbler (14, 16).

Description: This invention relates to key-actuated locks of the pin tumbler type. This type of lock has a cylindrical core rotatable in a lock housing, there being a plurality of pin tumblers received in bores journalled in the core and in the lock housing. The pin tumblers are of two types: core pins and housing pins. Each bore contains a set of one core pin and one housing pin, biassed towards the core. A key slot is formed in the core. Insertion of a key having the correct notches or bits aligns the junction between each set of core and housing pins with the rotational path of the core in the housing, and the core is permitted to rotate within the housing, thus unlocking the latch or the like on which the lock operates. If the incorrect key is inserted, the rotational path is blocked by one or more pins and the core cannot rotate. BACKGROUND ART This type of lock is susceptible to unauthorised opening, especially by use of keys milled or filed to resemble the correct key. This lock is also susceptible to "picking" to achieve unauthorised opening. Consequently, many systems have been proposed to ensure that the lock can be operated only by insertion of the correct key. For example, in US Patent Specification No. 2,087,554 (Schoorel) the lock described includes a rotatable cylindrical core having a plurality of pin tumblers received in bores journalled in the core and lock housing. The pin tumblers comprise a core pin and a housing pin, biassed towards the core and having a pin junction between. A spring-loaded ball member is provided to bias at least some of the pin tumblers upwards, towards the lock housing. Picking of the lock is therefore made difficult because some of the pins require upward movement and others require lowering in order to achieve correct alignment for opening. The key for the lock has disengagement means in the form of a side rib directed at right angles to the shank of the key which side rib acts to disengage the spring-loaded ball member. Other locks may use supplementary or auxiliary pins. For example, US Patent Specification No. 4,213,316 (Tietz) uses, as well as pin tumblers, supplementary pins located in bores in the core and biassed towards the centre thereof. To operate this lock it is necessary to use a key with two opposed locking ribs of the correct depth. These contact the supplementary pins and align them to abut the rotational path of the core. If the ribs are of insufficient depth, the supplementary pins will be short of abutment with the rotational path and, after a certain degree of rotation of the core, a pin tumbler, which is in the same plane as the supplementary pins, will partially enter the supplementary pin bore and jam further rotation of the core. In US Patent Specification No. 4,434,636 (Evva-Werk), the lock includes, as well as the conventional tumbler pins, auxiliary tumbler elements movable at an oblique angle relative to the keyway and being engageable at one end in arresting recesses in the housing. US Patent Specification No 4.377,082 (DOM) also includes auxiliary tumblers actuated, in this case, by a rolling element in the key. US Patent Specification No. 4,608,842 (Zeiss Ikon) employs three types of auxiliary tumblers operated by a key with opposed ribs. It will be appreciated that all these prior art locks involve the use of supplementary or auxiliary pins and therefore manufacture of these locks requires a substantial degree of engineering. Not only do these prior art locks cost a great deal more to produce, they are also susceptible to problems due to any imprecision in manufacture. It is an object of the present invention to provide a lock which addresses many of the same problems as the prior art, but which provides solutions with relatively simple mechanisms. In particular, it is an object of this invention to provide such a lock which does not require auxiliary tumblers. One continuing difficulty with locks of the pin tumbler type relates to key restriction systems. In many prior art arrangements, a key blank of unique profile is provided for a customer or manufacturer in order to control or prevent unauthorised key cutting for a particular group of locks. However, the duplicating of keys usually involves the removal of material from the key blank. Under present conventional systems, key cutters may be able to locate an unrestricted key blank profile similar to a restricted key blank and to mill or file the unrestricted blank until it matches the restricted profile. FR 2,280,772 (Rhone-Isere) shows a cylinder lock for which a key having a cruciform cross-section is required to operate the lock. It is an object of the present invention also to provide an arrangement and system such that a restricted key blank cannot be duplicated merely by removing material from a generally available profile. It is a further object of this invention to provide a lock system in which, in one embodiment, insertion of an incorrect key can result in jamming of the lock. BRIEF SUMMARY OF THE INVENTION In its broadest form, the present invention relates to a key-actuated pin tumbler lock of the type having: a cylindrical core rotatable in a lock housing via a rotational path, a plurality of pin tumblers received in bores journalled in the core and lock housing, each bore containing a set of pin tumblers comprising one core pin and one housing pin, biassed towards the core, and having a pin junction therebetween, a retaining mechanism, and a key slot in the core, whereby insertion in the key slot of a key having thereon suitable bits is adapted to align the pin junctions with the rotational path of the core in the lock housing, and to permit the core to rotate within the housing, characterised in that the retaining mechanism is biassed to engage at least one of the pin tumblers and to resist movement of the or each engaged pin tumbler in either direction in its respective bore until released by insertion in the key slot of a key including disengagement means for disengaging the retaining mechanism from the or each engaged pin tumbler. Preferably, the pin tumblers and bores are located in a single plane which is the same as the plane of the suitable bits on the key, and the disengagement means is located in a different plane. In a particularly preferred embodiment, the disengagement means comprises a wing formed on the key, for example, at right angles to the plane in which the bits are located. The retaining mechanism preferably includes a spring received in a groove located in the core and biassed towards engagement with one core pin. The retaining mechanism may also include release means such as a rotatable ball adapted to release the spring from engagement with the one core pin, under the influence of disengagement means on the key. The spring may, of course, engage a plurality of core pins, there being provided a plurality of release means. However, for the sake of simplicity, this embodiment is generally described herein in connection with the engagement of one core pin. The invention is not so limited. The lock of the invention may further include a locking bar, such as a trap received within a recess in the core and, in the locked position, adapted to extend through the rotational path into a side bar cavity in the lock housing, the trap being adapted to be withdrawn from the side bar cavity and the rotational path by means of withdrawal means on the key. The withdrawal means preferably comprise a notch or the like cut into the wing of the key, the trap being biassed towards the core. It will be immediately apparent to one skilled in the art that, by including a plurality of retaining mechanisms and locking bars, it is possible to greatly increase the number of possible permutations in the lock and key combinations of the present invention. It will also be apparent to one skilled in the art that a special key blank is required to cut a key for operating the lock of the present invention. Such a key blank is novel in that it need include only a single wing. Accordingly, this invention also provides a key blank suitable for manufacturing the key for operating the lock of the invention, the key blank having in one plane a shank in which the suitable bits may be formed and in a different plane a wing comprising the disengagement means or in which the disengagement means may be formed. Preferably, as already indicated, the plane of the wing is at right angles to the plane of the shank. The wing may extend for substantially the length of the shank or may extend for a lesser distance. This invention also provides a key for operating the lock of the invention, the key having in one plane a shank having formed therein the suitable bits and in a different plane a wing comprising or containing the disengagement means. The invention also provides the combination of the lock of the invention and a key adapted for insertion in the key slot, the key including, as well as the suitable bits, means for disengaging the retaining mechanism from engagement with the or each biassed pin tumbler. BRIEF DESCRIPTION OF THE DRAWINGS Certain embodiments of the invention will now be described in more detail with reference to the accompany drawings, in which: Figure 1a is a partially exploded perspective view of a lock embodying the invention; Figure 1b is a cross-section of a correctly-profiled key for the lock of Figure 1; Figure 1c is a cross-section of an incorrectly-profiled key for the lock of Figure 1; Figure 2 shows an inverse view of the lock of Figure 1; Figure 3 is a partial cross-sectional view of the lock of Figure 1, in the locked position; Figure 4 shows, in a similar partial cross-section, the lock in the open position; Figure 5 shows, in similar partial cross-section, the lock when a key of incorrect profile is inserted; Figure 6 illustrates in perspective view a variation of the lock of Figures 1 to 5, having a plurality of retaining mechanisms; Figure 7a shows in perspective view a lock of the invention including locking bars; Figure 7b is an enlarged view of a trap; Figure 7c shows in cross-sectional view the lock with the trap in the locked position; Figure 7d shows in cross-sectional view the lock with the trap in the unlocked position; and Figure 8 illustrates part of a key of the present invention. Referring first to Figure 1a, in this embodiment the pin tumbler lock indicated generally at 10 has a largely conventional cylindrical core 12 and a number of pin tumblers, one pair of which is illustrated as core pin 14 and housing pin 16, biassed towards core 12 by spring 18 (only one of which is shown). Core pin 14 and housing pin 16 meet at pin junction 20. Pin tumblers 14 and 16 are received in bores 22 in core 12 and in colinear bores 23 (see Figure 7a) in lock housing 24. Key slot 28 extends through core 12. Figure 5, for example, illustrates the rotational path 30 of core 12 in housing 24. Key 31 in Figure lb has conventional bits 33 (refer Figure 8 in which one bit 33 is shown) formed in shank 26 as well as disengagement means comprising a wing 35 of approximately 1 mm in depth. Key 44 in Figure 1c has conventional bits (not shown) formed in shank 26 but lacks a wing. Pin tumblers 14 and 16 and bores 20 are located in the vertical plane, while wing 35 is in the horizontal plane. Spring 32 and ball 34 together comprise the retaining mechanism. Spring 32 is received in a relatively shallow (for instance, 1 mm deep) groove 36 which extends around the circumference of core 12. Groove 36 includes a hole 38 for receiving ball 34. Tension key 42 of spring 32 is anchored in base 40. Referring now to Figure 3, this is a cross-section taken at the level of groove 36 and shows lock 10 in the normal locked position. Note that spring 32 engages pin 16. To enhance engagement, grooves 56 are provided on pins 14 and 16. Grooves 56 may of course be omitted in favour of frictional engagement between spring 32 and pin 14 or 16. Figure 4 illustrates lock 10 in an unlocked state when the correct key 31 is inserted. Because key 31 has the correct wing 35, ball 34 is forced to engage spring 32, so as to open gap 46 and allow core pin 14 and housing pin 16 to assume their correct orientation wherein pin junction 20 is aligned with rotational path 30 when key 31 is fully inserted. In Figure 5, an incorrect key 44 has been inserted. Because key 44 lacks wing 35, core pin 14 has been pushed up by insertion of key 44 but cannot assume its correct position, even for an otherwise correctly cut key. Spring 32 engages core pin 14 and interferes with it, thereby preventing core 12 from rotating in housing 24. (Extra grooves 56 are provided on the lower part of pin 14 to enhance engagement by spring 32. For clarity, these grooves are shown only in Figure 5.) Lock 10 is jammed and cannot be opened until a correctly profiled key is inserted to reset core pin 14. It will be appreciated that the lock of the present invention also provides improved pick resistance. The picking process is made considerably more complicated, since ball 34 must be held out while continuing the normal picking procedure on the tumblers. When more than one ball 34 and spring 32 is provided, either on the same or different parts of key slot 28, this can further frustrate picking. One such embodiment is shown in Figure 6, omitting springs 32 and balls 34 for clarity. Key 31 is capable of an enhanced number of combinations compared to prior art keys. For example, as illustrated, key 31 has wing 35 on the right hand side. As an alternative, key 31 may have wing 35 on the left hand side, with spring 32, ball 34 and groove 36, etc., also being on the left hand side of core 12. Bits 33 may be the same for both versions of key 31. However, a left hand winged key would not operate a right-hand oriented lock, and vice versa. A master key with both left and right hand blades would operate both locks, provided key slot 28 was of the appropriate shape. Turning now to Figures 7a to 7d, lock 10 has, as well as ball 34 which can push against spring 32, a trap 48 which is received in core 12 and which is receivable in a side bar recess in housing 24 (not shown). Ball 34 and spring 32 have been omitted from Figure 7a, for clarity. Groove 36a is suitable to receive a spring 50 which is shorter than spring 32. Hole 38a is suitable to receive a trap 48. Groove 36a and hole 38a have been shown empty, for clarity. Trap 48 received in hole 38b communicating with groove 36b is in the unlocked position, while trap 48 received in hole 38c communicating with groove 36c is in the locked position. Core 12 would include at least one spring 32 in a groove 36 and at least one ball 34 as in Figure 1a, for example, but these have been omitted from Figure 7a for clarity. A detailed view of trap 48 is shown in Figure 7b. Trap 48 includes groove 54 in which is received spring 50, which biases trap 48 towards core 12. When insertion of key 44 (see Figure 8) commences in key slot 28, wing 35 pushes on end 58 of trap 48 and enables trap 48 to act as a locking bar to jam lock 10, as shown in groove 36c of Figure 7a and in Figure 7c. Provided key 44 has the correctly located notch 52, as key 44 fully enters key slot 28, end 58 will enter notch 52 (the withdrawal means) under the influence of spring 50 and trap 48 will assume the position shown in Figure 7d. Trap 48 then clears rotational path 30 of core 12 and permits operation of lock 10. If key 44 is otherwise correct but lacks notch 52, lock 10 will be jammed. As shown in Figure 6, lock 10 may include a number of springs 32 and balls 34. Lock 10 may also include a number of traps 48. The correct key 31 includes the wing 35 appropriate to cause disengagement of all the springs 32 and also includes the notches 52 appropriate to release the traps 48. It will be seen from the above description that the present invention avoids the problem encountered in the prior art of having to introduce auxiliary tumblers to achieve both a high level of security and also a large variation in lock and key combinations. Variations and additions are possible within the scope of the invention, as will be apparent to those skilled in the art.

Claims: A key-actuated pin tumbler lock (10) of the type having: a cylindrical core (12) rotatable in a lock housing (24) via a rotational path, a plurality of pin tumblers received in bores (22) journalled in the core (12) and lock housing (24), each bore (22) containing a set of pin tumblers (14,16) comprising one core pin (14) and one housing pin (16), biassed towards the core (12), and having a pin junction (20) therebetween, a retaining mechanism (32,34), and a key slot (28) in the core (12), whereby insertion in the key slot (28) of a key (31) having thereon suitable bits (33) is adapted to align the pin junctions (20) with the rotational path (30) of the core (12) in the lock housing (24), and to permit the core (12) to rotate within the housing (24), characterised in that the retaining mechanism (32,34) is biassed to engage at least one of the pin tumblers (14,16) and to resist movement of the or each engaged pin tumbler (14,16) in either direction in its respective bore (22) until released by insertion in the key slot (28) of a key (31) including disengagement means (35) for disengaging the retaining mechanism (32,34) from the or each engaged pin tumbler (14,16). The lock (10) as claimed in claim 1, wherein the pin tumblers (14,16) and bores (22) are located in a single plane, the suitable bits (33) on the key (31) are located in the same plane and the disengagement means (35) is located in a different plane. The lock (10) as claimed in claim 1 or 2, wherein the retaining mechanism (32,34) includes a spring (32) received in a groove (36) located in the core (12) and biassed towards engagement with one core pin (14). The lock (10) as claimed in claim 3, wherein the retaining mechanism (32,34) further includes a release means adapted to release the spring (32) from engagement with the one core pin (14), under influence of the disengagement means (35) on the key (31). The lock (10) as claimed in claim 4, wherein the release means is a rotatable ball (34). The lock (10) as claimed in claim 4 or claim 5, which further includes a locking bar comprising a trap (48) received within a recess in the core (12) and, in the locked position, adapted to extend through the rotational path (30) into a side bar cavity (38a) in the lock housing (24), the trap (48) being adapted to be withdrawn from the side bar cavity (38a) and the rotational path (30) by means of withdrawal means (35) on the key. The lock (10) as claimed in claim 6, wherein the trap (48) is biassed towards the core (12) and is adapted to be urged towards the locked position by the disengagement means (35). The lock (10) as claimed in claim 6 or 7, which has a plurality of the springs (32), rotatable balls (34) and locking bars. The combination of the lock (10) as claimed in claim 1 and a key (31) adapted for insertion in the key slot (28), the key (31) including, as well as the suitable bits (33), means (35) for disengaging the retaining mechanism (32,34) from engagement with the or each biassed pin tumbler (14,16). The combination of the lock (10) as claimed in claim 2, and a key (31) adapted for insertion in the key slot (28), the key (31) having in the one plane a shank (26) having formed therein the suitable bits (33) and in the different plane on each side of the shank (26) a wing comprising the disengagement means (35) or in which the disengagement means (35) may be formed. The combination as claimed in claim 10, wherein the different plane is at right angles to the one plane.

Inventors: PREDDEY BRIAN, PREDDEY, BRIAN
Applicants: MASTER LOCKSMITHS ASS OF AUSTR, MASTER LOCKSMITHS ASSOCIATION OF AUSTRALASIA LIMITED
Application year: 1993
Main classification: E05B27
IPC codes: E05B19, E05B27