Technical Field of the Invention

The present invention relates to a cylinder lock designed to break along at least one pre-determined notch whereby the remaining cylinder can still prevent unauthorized access with an enhanced additional security.

Background of the Invention

Break-in attempts against locks are generally accomplished by use of hand tools suitable for engaging with an outer face of a cylinder lock and in the form to grasp said outer contour of the cylinder in order for applying pressure on the cylinder by twisting the same. These tools specially adapted for the specific purpose of breaking the cylinder effect breaking along the most vulnerable part of the cylinder; that is around the bridge part in between two cylinder halves wherein the cylinder is mounted to the door by a mounting screw.

There are known lock cylinders having, as a security means, a mechanically weakened portion whereby the remaining cylinder can still prevent unauthorized access. With this security improvement, the burglar is prevented from clamping the cylinder or the rotatable cam from outside with the help of a pliers-type gripping tool in order to apply a buckling force until it breaks the said central part.

This device provides a security against an act of vandalism consisting in gripping the cylinder by its front section with a pliers type tool and applying force from right to left, and once the cylinder is broken along the central zone, the burglar acts on the rotary cam in order to activate the door opening mechanism and penetrate inside the house.

A prior art publication in the technical field of the present invention may be referred to as EP2722470 (Bl) among others, the document disclosing a cylinder lock having a mechanically weakened notch cut out on the outdoor end of the second cylinder half for forming a breakable tip portion on said second cylinder half. One of the disadvantages of such a cylinder lock having a breakable notch is that after breakage of the cylinder lock and/or cylinder plug, remaining tumbler pins are easily accessible for against any further intrusion. For example, by means of a wire or the like, said tumblers can be further tampered and moved. Since a small number of tumblers remain in the cylinder lock such cylinder can then be unlocked easily.

Objects of the Invention

The main object of the present invention is to provide a cylinder lock with an enhanced security against break-in attempts which is arranged to retain the cylinder plug in its housing against any further intrusion.

Another object of the present invention is to provide a lock cylinder which is still operational in terms of preventing unauthorized access after a part of the cylinder lock is detached.

Summary of the Invention

The present invention relates to a cylinder lock comprising: a cylinder plug having a keyway adapted to receive a key; a longitudinally extending first cylinder half and a second cylinder half; a rotatable cam co-axial with and connected to the cylinder plug for rotation therewith, the rotatable cam being disposed externally of and between the first second cylinder halves; a mechanically weakened cylinder notch provided through at least part of the first cylinder half for forming a breakable tip portion; a mechanically weakened plug notch provided through at least part of the cylinder plug for forming a breakable plug portion; a plurality of mutually aligned bores extending at right-angles to the cylinder plug axis and in which housing pins which are substantially of equal length and plug pins which are of different lengths are biased in the direction of the keyway under spring force by a plurality of springs, said cylinder lock further comprises at least one retaining pin, pre-stressed and displaceable under a spring force, provided at the cylinder plug and depressed by a retaining member, said retaining pin adapted to match at least partly with a corresponding retaining recess formed at the first cylinder half such that when the mechanically weakened cylinder notch and plug notch breaks away, said retaining member slides out of the first cylinder half and said retaining pin maintains rest of the cylinder plug in the first cylinder half by matching with the hole. Such a cylinder lock can be used in a door or the like.

Brief Description of the Figures

Accompanying drawings are given solely for the purpose of exemplifying a cylinder lock whose advantages over prior art were outlined above and will be explained in detail hereinafter:

Fig. 1 demonstrates an exploded view of the cylinder lock wherein a cylinder plug is shown according to the present invention.

Fig. 2 demonstrates a front view of the hinge according to the present invention.

Fig. 3 demonstrates a cross sectional view taken along A-A in Fig. 2.

Fig. 4 demonstrates a partially sectional cylinder lock according to the present invention.

Fig. 5 demonstrates a partially sectional cylinder lock wherein breakable portions of the cylinder lock are shown apart according to the present invention.

Fig. 6 demonstrates a perspective view of a cylinder lock wherein breakable portions of the cylinder lock are shown apart according to the present invention.

Fig. 7 demonstrates a perspective view of a cylinder plug for a cylinder lock according another embodiment of the invention.

Fig. 8 demonstrates a cross sectional view of an engagement of a retaining pin and a housing pin with a slot as a second blockage position according to the present invention.

Fig. 9a demonstrates a cross sectional view taken along B-B in Fig. 4.

Fig. 9b demonstrates a cross sectional view taken along C-C in Fig. 4.

Fig. 10 demonstrates a cross sectional view of the cylinder plug shown in Fig. 7 where a spring loaded hardened member is depressed by a retaining member.

Fig. 11a demonstrates a cross sectional view of a cylinder lock where a retaining member is engaged with a slot of a housing pin such that rotation of a cylinder plug is prevented when the cylinder plug is rotated clockwise, according to the present invention.

Fig. lib demonstrates a cross sectional view of a cylinder lock where a retaining member is engaged with a slot of a housing pin such that rotation of a cylinder plug is prevented when the cylinder plug is rotated counterclockwise, according to the present invention.

Detailed Description of the Invention

In this part, the invention will be described in detail with reference to the figures given in the annex of the description. The reference list used in the figures is herein below:

10 Cylinder lock

21. Rotatable cam

22. Notch

23. First cylinder half

24. Second cylinder half

26. Slot

27. Retaining recess

29. Cylinder notch

30 Cylinder plug

31. Retaining member

32. Retaining pin

33. Thrust spring

34. Protrusion

35. Key way

36. Plug notch

37. Pin housing

38. First hardened member

39. Second hardened member

41. Tapped hole

42. Groove

43. Third hardened member 44. Member spring

51. Spring

52. Housing pin

52a. Housing pin

53. Plug pin

54. Aligned bore

In the prior art, forced withdrawal of the cylinder plug (30) can cause the plug pins (53) to be sheared off in the separating joint so that a suitable tool can force rotation of the rotatable cam (21). The present invention overcomes the above-mentioned shortcomings by way of providing a special mechanical weakened notches along the cylinder lock (10) and the cylinder plug (30), said line being mechanically weakened to be ruptured in response to a breaking force applied by a suitable hand tool. Further, as a second security feature said retaining pin (32) retains the rest of the cylinder plug (30) in the cylinder lock (10) by blocking movement of the housing pin (52a). The cylinder lock (10) according to the present invention is arranged to have an increased safeguard against break-in attempts.

According to a preferred embodiment, said cylinder lock (10) comprising: a cylinder plug (30) having a keyway (35) adapted to receive a key; a longitudinally extending first cylinder half (23) and a second cylinder half (24); a rotatable cam (21) co-axial with and connected to the cylinder plug (30) for rotation therewith, the rotatable cam (21) being disposed externally of and between the first second cylinder halves (23, 24); a mechanically weakened cylinder notch (29) provided through at least part of the first cylinder half (23) for forming a breakable tip portion (28); a mechanically weakened plug notch (36) provided through at least part of the cylinder plug (30) for forming a breakable plug portion (22); a plurality of mutually aligned bores (54) extending at right-angles to the cylinder plug axis and in which housing pins (52) which are substantially of equal length and plug pins (53) which are of different lengths are biased in the direction of the keyway (35) under spring force by a plurality of springs (51). Said aligned bores (54) can be clearly seen in Fig. 4, preferably at the end of the said aligned bores (54) said housing pin (52a) is disposed. said cylinder lock (10) further comprises at least one retaining pin (32), pre-stressed and displaceable under a spring force, provided at the cylinder plug (30) and depressed by a retaining member (31), said retaining pin (32) adapted to match at least partly with a corresponding retaining recess (27) formed at the first cylinder half (23) such that when the mechanically weakened cylinder notch (29) and plug notch (36) breaks away, said retaining member (31) slides out of the first cylinder half (23) and said retaining pin (32) maintains rest of the cylinder plug (30) in the first cylinder half (23) by matching with the retaining recess (27). A tapped hole (41) can be provided in a direction transverse to the axis of rotation for securing the cylinder lock (10) in an aperture in a door.

According to the present invention, said cylinder lock (10) has two security options for break-in attempts in cylinder locks. One of the security features is that locking the cylinder plug (10) by triggering the retaining pin (32) and other security feature is that blocking the movement of the cylinder plug (10) in case of any removal of the retaining pin (32) in its seated retaining recess (27) by moving the retaining pin (32) to the slot (26) of the housing pin (52a). The retaining pin (32) works as a barrier mounted in a pin housing (37) for displacement in the first cylinder half (23) and being biased in the direction of the plug pins (53) by a thrust spring (33).

When the cylinder plug (30) is withdrawn from the first cylinder half (23) by force, as shown in Fig. 5, the thrust spring (33) is able to push the retaining pin (32). Consequently, the retaining member (31) slides out and retaining pin (32) enters the retaining recess (27) opened up by the withdrawn cylinder plug (30). Said retaining pin (32) has a shoulder form increased in diameter such that the movement of the retaining pin (32) is limited upon removal of the retaining member (31).

As shown in fig. 3, one of the housing pins (52a) and one of the plug pins (53) are arranged in a same vertical axis (X) according to the longitudinal axis of the cylinder lock with the retaining pin (32). Further, the housing pin (52a) has at least one slot (26) adapted to receive at least partly the retaining pin (32) such that said housing pin (52a) blocks movement of the cylinder plug (30) as a second security feature when the retaining pin (32) is removed from the recess (27) and the cylinder plug (30) is rotated. In any break-in attempts, the cylinder plug (30) and the cylinder lock (10) are broken from their mechanically weakened notches such that said retaining pin (32) is triggered and pushed to the retaining recess (27) under the spring force from the thrust spring (33) located therein. Even it is removed from its retaining recess (27) still can be blocked by the slot (26) when the cylinder plug (30) is rotated axially. Said retaining pin (32) is configured to match with the slot (26) of the housing pin (52a) when the retaining pin (32) is removed from the retaining recess (27) and the cylinder plug (30) is rotated between 160° and 200°, more preferably 180, thus secured against rotation.

In a preferred embodiment, the retaining member (31) can have a protrusion (34) arranged to fit in a groove (42) formed on the breakable plug portion of cylinder plug (30) such that when the cylinder plug (30) breaks away or is pulled, said retaining member (31) goes out with the breakable portion of the cylinder plug (30) by removing the pressure on the retaining pin (32). Said protrusion (34) can be formed as a sleeve which extends in the longitudinal axis (Y) of the cylinder lock (10). Said protrusion can have a shape of a semi dome which is shaped and dimensioned to fit the corresponding groove (42) further, it can be attached by using adhesive material thereof.

As shown in fig. 3, a second cylinder half (24) can be used at the opposite side which defines a second bore having a second cylinder plug mounted therein, which is adapted to receive an external input and thereby be rotated within the second bore, and wherein the axis of rotation of the second cylinder plug is co-axial with the axis of rotation of the cylinder plug (30) and the rotatable cam (21), which the rotatable cam (21) is also connected to the second cylinder plug for rotation therewith. The rotatable cam (21) can also be configured to rotate with either the cylinder plug (30) or the second cylinder plug.

In a preferred embodiment, said mechanically weakened cylinder notch (29) and the mechanically weakened plug notch (36) are arranged in a same vertical axis (X) according to the longitudinal axis (Y) of the cylinder lock with the retaining pin (32) such that both notches can be broken away at the same time. In another embodiment, one end of the retaining recess (27) facing outside of the cylinder lock (10) can be closed for eliminating access to the retaining pin (32) after any break-in attempt. In fig. 8, a cross sectional view of the retaining pin (32) and the housing pin (52a) having a slot corresponding slot (26) where the said parts are engaged with each other are shown. When the retaining pin (32) is removed from the retaining recess (27) and the cylinder plug (30) is axially turned, the retaining pin (32), serving as a second security feature, is fastened at the slot (26) of the housing pin (52a) such that the rotation of the cylinder plug (30) is prevented.

As a further safeguard, more than one retaining pins (32) and corresponding recesses (27) may be provided on the first cylinder half (23). It is evident that the retaining pin (23) is disposed sufficiently vertically in the cylinder lock (10) that the function of the housing pins (52) and of the plug pin (53) is not adversely affected.

As a further safeguard, as shown in fig.1, at least one hardened member (38, 39) can be used against drilling in the cylinder lock (10), especially, in the cylinder plug (30). In a preferred embodiment, a first hardened member (38) extending in a transverse direction of the cylinder lock (10). Similarly, a second hardened member (39), which is preferably shaped as the first hardened member (38) and in a smaller size extending in a transverse direction of the cylinder lock (10). Said hardened members (38, 39) can be made of any chosen material, which may be different from the brass material from which the main part of the cylinder plug (30) is normally made. For instance, the hardened members (38, 39) may be made of stainless steel or hardened steel.

As shown in Fig. 1 and 3, the first hardened member (38) sits in an elongated recesses of the cylinder plug (30) and is, substantially, cylindrically formed. Similarly, the second hardened member (39) sits in another elongated recesses of the cylinder plug (30) and is, substantially, cylindrically formed. Fig. 7 demonstrates a perspective view of the cylinder plug (30) for the cylinder lock (10) according another embodiment of the invention. In this embodiment, a third hardened member (43) can be used against drilling as the first hardened member (38) used in the cylinder plug (30). Said third hardened member (43) can be formed as a semi-circle with a flat lower portion and an arc-shaped upper portion. Said third hardened member (43) is shaped and dimensioned to sit in a corresponding seat in the first cylinder half (23), which is also elastically loaded by at least one member spring (44). In a possible embodiment, two member springs (44) are located at the opposite ends of the flat lower portion of the third hardened member (43).

Said third hardened member (43) is pre-stressed and displaceable under the spring force, and is depressed by the retaining member (31) as shown in fig. 10. Said third hardened member (43) is adapted to match at least partly with a corresponding seat formed at the first cylinder half (23) such that when the mechanically weakened cylinder notch (29) and plug notch (36) breaks away, said retaining member (31) slides out of the first cylinder half (23) and said third hardened member (43) engage with the seat wherein reintroduction of the retaining member (31) is prevented.