Lock with curved keyway and flexible key

Abstract: A lock assembly includes a lock body (1, 1A, 1B, 1C, 1E, 1G) having tumbler members (13, 331, 332, 333, 334) and a curved keyway (12, 321, 322, 323, 18′), and a flexible key (2A, 2B, 2C, 2D, 2E, 3) to be received in the curved keyway (12, 321, 322, 323, 18′) and having key bit projections (221) for actuating the tumbler members (13, 331, 332, 333, 334). The flexible key (2A, 2B, 2C, 2D, 2E, 3) has a degree of stiffness sufficient enough to allow said key (2A, 2B, 2C, 2D, 2E, 3) to be inserted into said curved keyway (12, 321, 322, 323, 18′).

Description: This invention relates to a lock assembly, more particularly to a lock having a curved keyway and a key which is flexible but has a degree of stiffness sufficient to allow necessary movement of the key inside the keyway in order to transmit a torque. Personal safety and protection of property are among the primary concerns of any family. This is the reason the search for an economical and compact pickproof lock has been the ultimate goal of every locksmith. A sectional view of a conventional mechanical padlock is shown in Figure 1. The padlock 8 has a keyplug 81 with an axial keyway 83 and a keyhole 82 for receiving a rigid key 80. The padlock 8 has tumbler pins 84 which prevent the rotation of the keyplug 81. The key bits of the key 80 actuate the tumbler pins 84 to permit the rotation of the keyplug 81. The rotation of the keyplug 81 moves the locking member 85, thus releasing the shackle 86. The main disadvantage of this conventional padlock is that it can be easily picked by a burglar using an ordinary paper clip or any similar article. It is also known to provide a lock with a curved keyway, and to form the key from a plurality of segments which are interconnected by joints and a longitudinal wire to hold the segments in engagement, whereby a universal flexure is possible. Such a lock and key are disclosed in US-A-2035798. An objective of this invention is to provide a lock with a curved keyway and a key that is semi-rigid, for which the picking of the lock with a paper clip or any similar article is extremely difficult. Accordingly, the present invention provides a lock assembly comprising: a lock body including a rotatable part having a curved keyway therein, and which is provided with tumbler members; and a flexible key receivable in said keyway and operable to actuate said tumbler members and to rotate said rotatable part when turned, said key having an inner end and an outer end, and comprising a plurality of knuckles hingedly connected to one another between said inner and said outer ends to allow a relative pivoting movement between adjacent knuckles about respective axes, some of said knuckles incorporating a key bit projection, characterised in that said knuckles are hingedly connected so that each of said respective axes are parallel to each other, whereby the flexible key has a sufficient degree of stiffness to allow said key to be inserted into said keyway and to transmit the required torsion when turned in order to turn the rotatable part. The proposed lock can be incorporated in a padlock, a door lock or a door knob. When incorporated in a door lock, the lock can be formed with two oppositely disposed keyholes and can be operated from either of the two keyholes. Other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a conventional lock assembly; Figure 2 is a schematic sectional view of a first preferred embodiment of a lock according to this invention; Figures 3A and 3C are illustrations of a first and a second preferred embodiment of a flexible key for a lock of this invention; Figure 3B is a second example of a knuckle arrangement for the flexible key of Figure 3A; Figure 4 is a schematic view illustrating a flexible key received in the keyway of a lock according to this invention; Figures 5A, 5B and 5C are schematic sectional illustrations of second, third and fourth preferred embodiments of a lock according to this invention; Figures 6A, 6B and 6C are illustrations of third, fourth and fifth preferred embodiments of a flexible key for a lock according to this invention; Figures 7A, 7B and 7C are illustrations of different locks incorporating this invention; Figure 8 is an exploded perspective view of a fifth preferred embodiment of a lock according to this invention; Figure 9 is a sectional view of the lock of Figure 8; Figure. 10 is an illustration of a sixth preferred embodiment of a flexible key for a lock according to this invention; Figure 11 is an illustration of a keyplug of a lock according to this invention; Figure 12 is an exploded view of a preferred embodiment of a keyplug of a lock according this invention; and Figure 13 is an exploded view of another preferred embodiment of a keyplug of a lock according this invention. A schematic sectional view of a first preferred embodiment of a lock according to this invention is shown in Figure 2. The lock 1A is a padlock having a keyplug 11 with a curved keyway 12. A plurality of tumbler pins 13 is provided in the lock 1A in a conventional manner and project into the keyway 12. A first preferred embodiment of a key for the lock 1A according to this invention is shown in Figures 3A and 3B. The key 2A has a hollow head portion 21a with two hollow sections 21b and 21c telescopically connected thereto. The head portion 21a and the hollow sections 21b and 21c are rectangular in cross-section. The body of the key 2A is formed as a plurality of knuckles 22 hinged to one another by hinge pins 24. The knuckles 22 are slidably attached to the head portion 21a and are contained by the hollow sections 21b and 21c. As shown in Figure 3B, the knuckles 22 adjacent to an outermost end of the key 2A have recesses that form key bit projections 221 which match with the tumbler pins 13. The innermost hollow section 21c has inclined edges 21d which expose the key bit projections 221 of the key 2A. The hollow section 21c has a flange tip 21e which is used for pulling the hollow section 21c away from the head portion 21a. The hollow sections 21b and 21c thus serve as a protective cover and guide for the body of the key 2A. The head portion 21a has an elongated groove 21f. The endmost knuckle 22 disposed at a position closest to the head portion 21a has a protruding button 23 slidably extending along the elongated groove 21f. When the key 2A is not in use, the protruding button 23 is moved to a headmost extreme end of the elongated groove 21f in order to pull the knuckles 22 inward. The flange tip 21e is then pulled outward, causing the hollow sections 21b and 21c to cover the knuckles 22. When using the key 2A, the protruding button 23 is moved to the opposite extreme end of the elongated groove 21f to extend the knuckles 22 away from the hollow sections 21b and 21c. The endmost knuckle 22 at the outermost end of the key 2A is then inserted into the keyhole 14 of the lock 1A. The hinge pins 24 allow the key 2A to bend so that the body of the key 2A can move along the keyway 12. The hollow sections 21b and 21c do not enter the keyway 12 since they are forced to retract into the head portion 21a by the action of pushing the key 2A into and against the lock 1A. The flange tip 21e extends outside the head portion 21a when the hollow sections 21b and 21c are retracted into the head portion 21a. The knuckles 22 provide the key 2A with the necessary degree of stiffness required to transmit torsion to the keyplug 11 so that the locking member 15 can be moved away from the shackle 16 when unlocking the padlock 1A. Figure 3B shows a second example of a knuckle arrangement for the key 2A of this invention. The knuckles 22' each have a substantially wedge-shaped projection 221' which serve as the key bit projections. Referring to Figure 3C, a second preferred embodiment of a key 2B for the lock 1A of this invention is shown to have a key bit portion 25 made of a flexible material. The key bit portion 25 has a level base end fixed by pins 262 in longitudinal grooves 261 of a plurality of aligned rectangular knuckles 26. The rectangular knuckles 26 provide the key 2B with the degree of stiffness required to transmit torsion to the keyplug 11. Figure 4 is a schematic view of still another example of a knuckle arrangement for a flexible key received into the keyway of a lock according to this invention. The knuckles 22'' are shown to be hinged to one another by hinge pins 24''. Figures 5A, 5B, and 5C are schematic sectional views of second, third and fourth preferred embodiments of a lock according to this invention. The locks Lb., 1c and 1d are door locks having keyways 321, 322 and 323 of different shapes and lengths. The position of the tumbler pins 331, 332, 333 and 334 may also be varied depending upon the shape of the keyway. As shown in Figure 5C, the lock 1d may have more than one group of tumbler pins 333 and 334 to make the lock 1d more difficult to pick. Figures 6A, 6B and 6C are third, fourth and fifth embodiments of a key for the locks of this invention. The body of the key 2C, which is illustrated in Figure 6A, comprises a plurality of longitudinally aligned rectangular plates 42 and an endmost substantially semi-circular plate 424 with a curved edge that is to be inserted in the keyhole. The rectangular plates 42 and the endmost plate 424 are joined to one another by hinge pins 423. The surfaces of the rectangular plates 42 and the endmost plate 424 are formed with a plurality of recesses 421 and 422 having different sizes and depths which are used for actuating the tumbler pins of the lock. The body of the key 2D, as illustrated in Figure 6B, comprises a plurality of axially aligned hollow cylindrical segments 43 joined to one another by hinge pins 432. The cylindrical segments 43 have recesses 431 which are used for actuating the tumbler pins of a lock with a keyway that is circular in cross-section. The key 2E, as shown in Figure 6C, is a modification of the key 2C illustrated in Figure 6A. The key 2E comprises a plurality of substantially semi-circular plates 44. Each of the semi-circular plates 44 has a rear notch 444 which receives a front semi-circular projection 443 of another semi-circular plate 44. The semi-circular plates 44 are joined to one another at the rear notches 444 by transverse hinge pins 442. The surfaces of the semi-circular plates 44 similarly have a plurality of recesses 441 for actuating the tumbler pins of the lock. The transverse hinge pins 442 only allow upward or downward movement of the semi-circular plates 44, unlike that of the hinge pins 423 of the key 2C which allow only left or right movement of the rectangular plates 42 and the endmost plate 424. As shown by the preferred embodiments, the plates which make up the body of the keys can have different sizes and shapes. The plates can be rectangular, circular, or even triangular in shape. The recesses of the key bodies are of different sizes and depths to make the locks more difficult to pick. Figures 7A, 7B and 7C are illustrations of different locks incorporating this invention. The fourth preferred embodiment, as shown in Figure 7A, is a door lock 1E which has no keyplug. The lock 1e has two keyholes 15' formed on two sides of the door so that the lock 1e may be operated from the inside or the outside of the door. The fifth preferred embodiment, as shown in Figure 7B, is a cylindrical keyplug 1F of a lock with two keyholes 16' accessible from two ends. The sixth preferred embodiment, as illustrated in Figure 7C, is still another door lock 1G which is incorporated in a door knob 17'. The door knob 17' is provided with a curved keyway 18'. Figure 8 is yet another preferred embodiment of a lock assembly of this invention. The lock 1 has a engaging disk 2 fixed near the keyway 12. The engaging disk 2 has positioning hole 21 formed therein and two oppositely radial notches 211 extending from the positioning holes 21. The key 3 includes an elongated hollow head portion 34 and a key bit portion 31 telescopically received in the hollow head portion 34. The key bit portion 31 is formed with a mild metal strip 313 and a plurality of knuckles 311. The knuckle 311 is formed with two parts each of which has a notch 312 for accommodating the metal strip 313 when they are engaged in a face to face relationship and is fixed to the metal strip 313 by small pins or screws 315. The hollow head portion 31 has a longitudinal sliding groove 342 formed therein and a slider 4 slidably mounted thereto. A rivet 5 is fixed to the slider 4 and one end 314 of the metal strip 313 and passes through the longitudinal sliding groove 342 so that the metal strip 313 can be retracted into or extend out of the hollow head portion 34 by moving the slider 4 along the longitudinal sliding groove 342. A resilient retaining member 41 with a projection 42 is mounted in the slider 4. The projection 42 engages with two spaced recesses 343 formed on the hollow head portion 34 to temporarily position the slider 4 with respect to the hollow head portion 34, as best illustrated in Figure 9. Two engaging grooves 344 are formed at one end of the hollow head portion 34 adjacent to the key bit portion 31. The engaging grooves engage the inner periphery of the position hole 21 of the engaging disk 2 when the key 3 is rotated 90 or 180 degree to unlock the lock 1 in order to prevent the key from slipping out from the keyway 12. Figure 10 shows a modification of the knuckles connect to the mild metal strip 313 in Figure 9. Each of the knuckles 51 has a through hole 511 formed therein so that the metal strip 313 can pass through the through holes 511 of the knuckles 51. Thus, the knuckles 51 are interconnected with each other along the metal strip 313 with the endmost knuckle 51 being fixed to the free end of the metal strip 313 by screws 52. This can facilitate the assembling speed of knuckles to the key. Figure 11 illustrates a modification of the engaging disk 2 in Figure 10. In this embodiment, a engaging cap 2 having a plurality of hooks 20 is provided the cap edge thereof which are engaged in the grooves 111 of the keyplug 11 of the lock 1. Therefore, the cap 2 can be fixed to the lock 1 and function as the engaging disk 2 of Figure 8. Since the keyway of the lock of this invention is curved, the keyplug of this invention is preferably formed with at least two components to prevent the curved keyway from penetrating the keyplug. The keyplug 11 may be formed with a upper portion 112 and a lower portion 113 in which the curved keyway 12 is formed. The upper and lower portions 112, 113 are connected together by pins 9, as best illustrated in Figure 12. Figure 13 shows another preferred embodiment of the keyplug 11 which is formed with three components which is particularly used with a keyplug having a hook-like curved keyway. In this form, the tumbler holes are advantageously molded in the keyplug 11 but not formed by drilling after the keyplug 11 has been formed. While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments, but is intended to cover various arrangements included within the scope of the appended claims.

Claims: A lock assembly comprising: a lock body (1,1A,1B,1C,1E,1G) including a rotatable part (11) having a curved keyway (12,321,322,323,18') therein, and which is provided with tumbler members (13,331,332,333,334); and a flexible key (2A,2B,2C,2D,2E,3) receivable in said keyway and operable to actuate said tumbler members and to rotate said rotatable part (11) when turned, said key having an inner end and an outer end, and comprising a plurality of knuckles (22) hingedly connected to one another between said inner and said outer ends to allow a relative pivoting movement between adjacent knuckles about respective axes, some of said knuckles (22) incorporating a key bit projection (221), characterised in that said knuckles (22) are hingedly connected so that each of said respective axes are parallel to each other, whereby the flexible key (2A, 2B,2C,2D,2E,3) has a sufficient degree of stiffness to allow said key to be inserted into said keyway (12,321,322,323,18') and to transmit the required torsion when turned in order to turn the rotatable part (11). A lock assembly as claimed in claim 1, characterised in that said key (2A) further comprises a hollow head portion (21a) and a plurality of hollow sections (21b,21b) telescopically connected to said hollow head portion (21a) to serve as a housing for said knuckles (22) when said key is not in use, said hollow head portion (21a) having an elongate slide groove (21f), one of said knuckles adjacent said inner end having a protruding button (23) slidably engaged in said elongate slide groove (21f). A lock assembly as claimed in claim 2, characterised in that an endmost hollow section of said telescopic hollow sections (21c) has an outlet opening defined by inclined edges (21d) which expose said key bit projections (221) of said key, and a flange tip (21e) serving as a pull handle which extends outside said head portion (21a) when said telescopic hollow sections (21b,21c) are retracted into said head portion (21a). A lock assembly as claimed in any preceding claim, characterised in that said lock is a door lock (1E) having two opposite sides each formed with one keyhole (15'), said door lock (1E) being unlockable from either of said two sides of said door lock (1E). A lock assembly as claimed in any preceding claim, characterised in that said lock is incorporated in a door knob (17'). A lock assembly as claimed in any preceding claim, characterised in that said lock body has a first engaging member (2) provided adjacent to said keyway (12) and said key (3) has a second engaging member (344) correspondingly formed thereon so that said first and second engaging members (2,344) can be engaged with each other when said key (3) is inserted into said keyway (12) and rotated to an unlocked position. A lock assembly as claimed in any preceding claim, characterised in that said rotatable part (11) is a keyplug, said keyplug comprising at least two components.

Inventors: HSU YUN TUNG, HSU, YUN TUNG
Applicants: HSU YUN TUNG, HSU, YUN TUNG
Application year: 1991
Main classification: E05B35
IPC codes: E05B19, E05B35