Security device for lock cylinders

Abstract

 A security device for lock cylinders, which consist of a plug-rotor (1) which is rotatable in a cavity of a lock cylinder housing (2), which locks use true keys (4) in which the combination for opening is by means of peaks and valleys of different sizes, with the valleys operating in conjunction with respective pairs of pins (5, 6), which each comprise a plug-rotor pin (5) and a lock cylinder housing pin (6) which is loaded by a spring (7), and the plug-rotor (1) incorporating a keyway (8) for insertion of the true key (4), in which there is provided a usual virtual line (9) corresponding to longitudinal alignment of the tips of the plug-rotor pins (5) when no key is inserted; characterised in that at least one of the plug-rotor pins (5) is formed as a security pin (10) which includes some end means which prevents the security pin (10) from reaching the usual virtual line (9) in the state in which the true key (4) is not inserted or the lock is empty, and its advance reaches only a virtual security line (9B) which is shorter than that of the usual virtual line (9).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a security device for lock cylinders, which is especially designed for locks which consist of a plug-rotor which is rotatable within a lock cylinder housing, and are operated using true keys in which the opening combination is cut by means of a succession of peaks and valleys of different sizes, with the valleys each operating in conjunction with pairs of pins which each comprise a plug-rotor pin which will be rotated together with the plug-rotor and a lock cylinder housing pin which, with rotation of the plug-rotor, will remain in the lock cylinder housing and is loaded by a spring, and the plug-rotor incorporating a keyway for insertion of the true key.

PRIOR STATE OF THE ART

[0002] A method has relatively recently become known for forcing the type of lock as described hereinabove, which method is both highly effective and very simple to execute, and is within the scope of people who, without being very skilful or particularly expert, have become trained in this serious practice in a short space of time.

[0003] For the sake of simplicity of explanation throughout the description, a lock cylinder with a European profile shall be described, that is, a lock cylinder with a pear-shaped lock cylinder housing, and a key with toothed combination indentations along an edge of the shaft thereof. However, the present invention also extends to other kinds of lock cylinders, such as those with an American profile, which have a circular lock cylinder housing, and also to so-called flat keys which have combination indentations along the flat surface of the shaft thereof.

[0004] This forcing method utilizes a false key. The valleys as defined by the teeth of the false key are cut deeply enough to allow the valleys to accommodate the plug-rotor pins when in the most advanced positions, that is, the positions as adopted when no key is inserted. Also, the stem or body of the false key has a slightly-reduced dimension at the distal end thereof as compared to that of the true key, such that the distal end of the false key which extends into the keyway is set back, and the false key can extend further in the keyway than the true key.

[0005] In this forcing method, the false key is first introduced into the keyway until the teeth contact the tip ends of the respective plug-rotor pins, but is inserted no further into the keyway, and then a sharp impact is made to the head of the false key, such that a rotation pulse is imparted to the false key, which causes the plug-rotor to rotate and the lock to open.

[0006] Analysis of this phenomenon has led other people to conclude that the impact on the false key is transmitted through the teeth thereof to the plug-rotor pins, which in turn transmit the impact to the lock cylinder housing pins, which retract against their respective springs, such that, for a brief moment, the plug-rotor can rotate. On the basis of this analysis, a solution has been proposed which consists of dividing the plug-rotor pins into two parts, and including a further spring therebetween, which is weaker than the spring which acts to bias the lock cylinder housing pin. With this arrangement, the energy of the impact is intended to be damped by the plug-rotor pins, and not transmitted to the lock cylinder housing pins. However, this attempted solution has not been successful, and this serious problem has hitherto remained unsolved.

EXPLANATION AND ADVANTAGES OF THE INVENTION

[0007] Accordingly, the present invention provides a security device for lock cylinders, which, as described hereinabove, consist of a plug-rotor which is rotatable in the cavity of a lock cylinder housing, and are unlocked using true keys which each include an opening combination as defined by means of peaks and valleys of different sizes, with the valleys operating in conjunction with respective pairs of pins, which each comprise a plug-rotor pin and a lock cylinder housing pin which is loaded by a spring, and the plug-rotor incorporating a keyway for insertion of the true key, in which there exists a usual virtual line which corresponds in location to longitudinal alignment of the tip ends of the plug-rotor pins when no key is inserted in the keyway, wherein at least one of the plug-rotor pins is formed as a security pin which includes some end means which prevents the tip end of the security pin from reaching the usual virtual line and provides that the tip end of the security pin extends only to a virtual security line which is shorter than the usual virtual line when other than the true key is inserted in the keyway.

[0008] The construction of the security device of the present invention has been devised based on a different analysis of the phenomenon than that proposed to date. Experimental studies have led to the deduction that the impact as imparted to the false key results in a resilient impact between the plug-rotor pins and the respective lock cylinder housing pins, such that the pins repel one another and separate far enough and for long enough to permit the plug-rotor to be rotated, such that the lock can be opened. During this repulsion, the lock cylinder housing pins are thrust against their respective springs and the plug-rotor pins are accommodated in the deep valleys as cut into the false or counterfeit key. In addition, this model for demonstrating the phenomenon which allows cylinder locks to be forced, makes it possible to show the lack of efficiency of the solution provided hitherto on the basis of an analysis which has proved to be incorrect.

[0009] The present invention encompasses various embodiments of the end means.

[0010] In one embodiment the security pin incorporates a peripheral projection at the rear end thereof which operates in conjunction with an inner rib in the security pin hole in the plug-rotor, such that the security pin is slideable in the security pin hole and the projection and the rib have dimensions which establish the required distance between the most advanced position of the end tip of the security pin and the usual virtual line, when the true key is not inserted in the keyway.

[0011] The present invention provides a simple solution, and is derived from correct and accurate observation of the phenomenon. Also, the effectiveness of the present invention has been proved experimentally as a security feature in relation to the above-described method for forcing cylinder locks. The functionality is apparent in that the plug-rotor pin is not effected by the forcing operation, since its end tip does not come into contact with the teeth of the false key, and consequently the lock cylinder housing pin which is spring biased will continue to extend across the rotational surface of the plug-rotor, thus preventing the latter from rotating, even though the other sets of pairs of pins would have succumbed to the action of forcing of the lock.

[0012] In order to be effective, the present invention needs to be applied only to one of the plug-rotor pins, though a plurality of the plug-rotor pins could be formed as security pins.

[0013] Also, the security pin can be any one of the plug-rotor pins as contained in the lock, and this pin can have variable length, in order to make it even more difficult to locate and configure the active elements which impede opening.

[0014] In addition, as will be seen in the following detailed description, the invention can be implemented such that, in the production process, it is possible to select which of the plug-rotor pins will be allocated as security pins in each manufactured lock, and this provides an additional security element, since it will not be known which pin is the security pin when a lock is put on sale.

[0015] The following detailed description illustrates specific features of the invention and some preferred embodiments of the end means, where applied to at least one of the plug-rotor pins.

DRAWINGS AND REFERENCES

[0016] In order better to understand the nature of the present invention, the attached drawings show a preferred form of an industrial embodiment, which is in the nature of a purely illustrative and non-limiting example.

[0017] Figure 1 is a longitudinal section of an indoor/outdoor double-bodied lock which is constituted according to the invention. The lock incorporates enlarged details of the security device, in two operating configurations. The left-hand side shows the configuration corresponding to insertion of the true key. The right-hand side shows the configuration corresponding to when no key is not inserted, and the lock is at rest.

[0018] Figure 2 is a view in cross-section showing an existing lock body, that is, without incorporating the device according to the present invention. The view is the same view as that shown in the left-hand side of Figure 1, but where no key is inserted.

[0019] Figures 3 and 4 are views similar to Figure 2, which illustrate the operative sequence used to force the lock. Figure 3 shows the first step of the forcing operation, and Figure 4 shows the second step of the forcing operation.

[0020] Figures 5 and 6 are equivalent views to Figures 3 and 4, but show a lock body which, like the left-hand side of Figure 1, incorporates the device according to the present invention.

[0021] Figure 7 is an equivalent view to the detail as shown in the left-hand part of Figure 1, but in which the internal rib is the result of an operation of machining the security pin hole.

[0022] In these Figures, the references indicated are as follows:

1. Plug-rotor

2. Lock cylinder housing

3. Radial area of lock cylinder housing (2)

4. True key

5. Plug-rotor (1) pin

6. Lock cylinder housing (2) pin

6B. External pin

7. Spring for lock cylinder housing (2) pin

8. Plug-rotor (1) keyway for true key (4)

9. Virtual line of plug-rotor pins (5)

9B. Virtual line of security pin (10)

10. Plug-rotor (1) security pin

11. Security pin (10) head

12. Inner rib

13. Security pin hole

14. False key

15. Elastic or rigid fitting/washer

DESCRIPTION OF A PREFERRED EMBODIMENT

[0023] With reference to the drawings, the Figures illustrate a security device for lock cylinders in accordance with a preferred embodiment of the present invention, which comprise a plug-rotor 1 which is rotatable in a cavity of a lock cylinder housing 2, which locks use true keys 4 to open the same in which the combination for opening is by means of peaks and valleys of different sizes, with the valleys operating in conjunction with respective pairs of pins 5, 6, which each comprise a plug-rotor pin 5 and a lock cylinder housing pin 6 which is loaded by a spring 7, and the plug-rotor 1 incorporating a keyway 8 for insertion of the true key 4, in which there is provided a usual virtual line 9 according to which there is longitudinal alignment of the tip ends of the plug-rotor pins 5 when the true key 4 is not inserted or the lock is empty.

[0024] As shown in Figure 1, at least one of the plug-rotor pins 5 is formed as a security pin 10, which has some end means which prevents the security pin 10 from reaching the usual virtual line 9 when the true key 4 is not inserted or the lock is empty, and the security pin 10 extends only to a virtual security line 9B which is shorter than that of the usual virtual line 9.

[0025] In a preferred embodiment, the end means comprises a projection 11 which is disposed to the periphery and at the rear end of the security pin 10 and operates in conjunction with an inner rib 12 in the security pin hole 13 in the plug-rotor 1, in which the security pin 10 slides with some play. The projection 11 and the inner rib 12 have dimensions which are in accordance with the required distance between the virtual security line 9B of the end tip of the security pin 10 and the usual virtual line 9, when the true key 4 is not inserted.

[0026] This construction of the security device of the present invention prevents a forcing operation of the kind as illustrated in Figures 3 and 4.

[0027] In this forcing operation, a false key 14 is prepared which comprises regular teeth having peaks and valleys, wherein the peaks pass beyond the usual virtual line 9 which defines the geometrical location of the tips of the plug-rotor pins 5 in the state of rest, and the valleys are deep enough to accommodate the plug-rotor pins 5 therein when fully contained in the plug-rotor 1, that is, thus permitting turning of the latter, which opens the lock.

[0028] This forcing operation comprises the steps of, firstly, introducing the false key 14 until the peaks of the teeth come into contact with the distal ends of the respective tips of the plug-rotor pins 5, as illustrated in Figure 3, and, secondly, applying a sharp impact to the head of the false key 14, which, as illustrated in Figure 4, causes the plug-rotor pins 5 and the lock cylinder housing pins 6 to be repelled from one another, thus permitting rotation of the plug-rotor 1, which opens the lock. The effectiveness of applying this impact is assisted by cutting back the shaft of the false key 14.

[0029] In the device of the present invention, at least one of the plug-rotor pins 5, as the security pin 10, never reaches the usual virtual line 9, that is, the security pin 10 never reaches the axis of rotation of the plug-rotor 1, and the rotation of the plug-rotor 1 is blocked by the counterpart external pin 6B.

[0030] Consequently, in relation to the present invention, the forcing operation as described hereinabove cannot modify the state of the plug-rotor 1, and, even if the other plug-rotor and cylinder housing pins 5, 6, succumb to this forcing action, the external pin 6B, which is counterpart to the security pin 10, continues to prevent rotation of the plug-rotor 1.

[0031] This solution is both simple and effective, and provides the additional security factor that, in the production process, it is possible to select at random any one or more of the plug-rotor pins 5 as the security pin 10, such that, from the exterior, it is not known which plug-rotor pin 5 has been selected. Nor can the length be determined, since this will be selected according to the cut of the true key 4 as provided during assembly, and since this cut is random, the relevant pin cannot be predicted.

[0032] There are various possibilities with regard to constituting the inner rib 12 in the security pin hole 13. These include the inner rib 12 being constituted by an elastic or rigid fitting which fits adequately into the security pin hole 13, or the inner rib 12 can be constituted by an elastic or rigid washer fitted to the security pin hole 13 and/or on the security pin 10.

[0033] There are also many simple solutions for the projection 11 of the security pin 10, the preferred embodiment being that which consists of a perimetric flange or enlargement which provides the security pin 10 with a head in the form of an inverted mushroom.

[0034] This present invention has been described in relation to lock cylinders with a European profile, but can also be applied to other profiles, such as the American profile, which has a circular lock cylinder housing.

[0035] Also, the invention described, which is represented using keys with combination indentations cut in an edge, can also be applied to so-called flat keys in which the combination indentations are cut in the flat surface of the shaft, and have a frusto-conical shape. In all cases, the combination is obtained by the permutation of peaks and valleys.

Claims

1. A security device for lock cylinders, which comprise a plug-rotor (1) which is rotatable in a cavity of a lock cylinder housing (2), and is operated using a true key (4) in which the combination for opening is by means of peaks and valleys of different sizes, with the valleys operating in conjunction with respective pairs of pins (5, 6), which each comprise a plug-rotor pin (5) and a lock cylinder housing pin (6) which is biased by a biasing element (7), and the plug-rotor (1) incorporating a keyway (8) for insertion of the true key (4) in which exists a usual virtual line (9) corresponding to longitudinal alignment of the tips of the plug-rotor pins (5); characterised in that at least one of the plug-rotor pins (5) is formed as a security pin (10), the tip of which extends only to a virtual security line (9B) which is shorter than the usual virtual line (9).

2. The security device of claim 1, wherein the security pin (10) includes stop means which prevents the security pin (10) from reaching the usual virtual line (9).

3. The security device of claim 2, wherein the stop means is configured to provide that the security pin (10) extends only to the virtual security line (9B) when no key is inserted in the keyway (8).

4. The security device of claim 3, wherein the plug-rotor (1) includes a security pin hole (13) which includes an inner rib (12) and in which the security pin (10) is slideable with play, and the stop means comprises a projection (11) at the periphery of the security pin (10) which engages the rib (12) to provide that the security pin (10) extends only to the virtual security line (9B) when no key is inserted in the keyway (8).

5. The security device of claim 4, wherein the projection (11) and the rib (12) have dimensions which are in accordance with a required distance between the virtual security line (9B) and the usual virtual line (9), when the true key (4) is not inserted.

6. The security device of claim 4 or 5, wherein one or both of the length of the security pin (10) and the position of the rib (12) are variable.

7. The security device of any of claims 4 to 6, wherein the rib (12) is defined by a fitting which is fitted at the security pin hole (13).

8. The security device of any of claims 4 to 6, wherein the rib (12) is defined by an elastic fitting which is fitted at the security pin hole (13).

9. The security device of any of claims 4 to 6, wherein the rib (12) is defined by a rigid fitting which is fitted at the security pin hole (13).

10. The security device of any of claims 4 to 6, wherein the rib (12) is defined by an elastic washer which is fitted at the security pin hole (13).

11. The security device of any of claims 4 to 6, wherein the rib (12) is defined by an elastic washer which is fitted at the security pin hole (13).

12. The security device of any of claims 4 to 6, wherein the rib (12) is defined by the security pin hole (13).

13. The security device of claim 12, wherein the rib (12) is formed when machining the security pin hole (13).

14. The security device according to any of claims 4 to 13, wherein the rib (12) is formed at any of the positions of the lock cylinder housing pins (6).

Drawing