A locking device

Abstract

A locking device (e.g. cylinder lock) includes a cylinder 12, a rotatable plug 14 defining a shear line 34 therebetween and a keyway for an electronic key. The plug houses a motor 38 that rotates a ca

Description

The present invention relates to a locking device and relates particularly, but not exclusively, to an electronic GUI? O cylinder lock used in a door lock or the like. Vulnerabilities with the design of cylinder locks have been extensively exploited to allow unauthorised access. Methods such as lock picking and bumping, a technique where a specially crafted key known as a bump key is used to manipulate the pins inside the lock to force it open, have been widely used. Additionally brute force attacks, such as using excessive physical force or tools like wrenches, can also be employed to break or pry open the lock. Furthermore, another such method that is practiced is the use of drills to compromise cylinder locks. As the drill spins the vibrations it generates can cause the lock pin to bounce erratically and momentarily align with the shear line. This brief alignment enables the user to exploit the window of opportunity through the rotating drill bit and allow for the rotation of the lock plug and eventual unauthorized entry. Preferred embodiments of the present invention seek to overcome or alleviate the above described disadvantages of the prior art. According to an aspect of the present invention there is provided a locking device comprising: a cylinder; a plug rotatable within the cylinder and defining a junction therebetween; a keyway for insertion of a key; a cam located within the plug; a motor activated by the key, for rotating the cam between a first and a second rotational position; a first pin biased towards the cam by a first biasing member; and a second pin biased towards the cam by a second biasing member wherein when in a locked condition the cam is in a first rotational position and either of the first and second pins straddles the junction thereby preventing rotational movement of the plug and when the motor is activated and the cam rotates into the second rotational position, the first and second pins move into an unlocked condition such that a surface of both the first and second pins align with the junction thereby allowing rotational movement between the plug and the cylinder. By including an arrangement whereby both pins can rest on the same cam facilitates their accommodation within a confined space. This compact configuration enables the integration of two pins within a notably limited area. The inclusion of a second pin provides the benefit by preventing forced entry into the lock by the use of a drill. During an attack with a drill the vibrational movement of the drill bit when pressed against the keyway causes the pins to bounce. By including two pins, the chance of both pins aligning above the shear line during drilling decreases significantly. Furthermore, each pin also includes its own biasing member. This dual-spring configuration increases the effectiveness of the lock against attack by providing independent tension to both pins. This further decreases the chance that the pins will both align above the shear line at the same time, further increasing the locks resistance against drilling attacks and enhancing the ability of the lock to withstand external forces and maintain security. This enhanced security can therefore be provided in a small device such as a euro cylinder where a motor takes up a significant portion of the plug. In a preferred embodiment the first pin includes a pin aperture and wherein the second pin extends into the pin aperture and wherein the second biasing member extends through the first biasing member. By having one pin extend into the other and one biasing member extend into the other enables compact but robust components to be used in the lock. It enables the space for two larger diameter pins to enter the space and promotes mutual reinforcement with the inner pin supporting and reinforcing the tubular outer pin. In an additional preferred embodiment, the first pin has a first mass, and the second pin has a second mass wherein, the first mass is different from the second mass. Including a first heavier pin within the lock plug introduces a weight disparity between the two pins. This difference ensures that each pin bounces at a unique rate when confronted with drilling attempts. That is, the heavier first pin will bounce at a lesser rate than the lighter second pin and initiate an asymmetry that complicates the drilling process for potential intruders. In a preferred embodiment the first biasing member includes a first tension, and the second biasing member includes a second tension, wherein the first tension is different from the second tension. Including two springs with different tensions introduces a force inequality acting on the two springs. That is, the first pin will have greater biasing force acting on it as compared to the biasing force acting on the second pin. This will reduce the rate at which the first pin can bounce compared to the second pin creating a unique bouncing pattern between the two. This will further reduce the chances of the two pins both bouncing above the shear line at the exact same time. In a further preferred embodiment, the plug further comprises an annular recess forming a wall. The wall, created by the annular recess in the plug, functions a sacrificial barrier. That is, if the keyway is subjected to a great force the wall will break and prevent rotation of the plug. Consequently, the keyway will turn indefinitely after the wall breaks but as the connection between the keyway and the plug is severed the plug will remain immobilized, irrespective of the position of the pins, and therefore rendering any further attempts to manipulate the lock futile . In another preferred embodiment the annular recess further comprises an aperture adjacent the wall and extending through the annular recess. In an additional preferred embodiment, the wall includes a thickness, and the plug includes a diameter wherein the thickness of the wall is less than 10% of the diameter of the plug. Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense with reference to the accompanying drawings in which:- Figure 1 is an exploded view of the lock of the present invention; Figure 2 is a cross-sectional view of the lock of figure 1; Figure 3 is another perspective view of the lock of figure 1; and Figure 4 cross sectional perspective view of a portion of the lock of figure 1. Referring initially to figures 1, 2 and 3 there is provided an electronic lock 10. The lock 10 includes a cylinder 12, a plug 14 and a keyway 16 for an electronic key (not shown). As can be seen from the figures, the cylinder 12 and plug 14 are of the type known to persons skilled in the art as a Euro cylinder. It should be noted that the present invention is not limited to the use of cylinders and plugs of this type. The cylinder 12 provides a housing within which the plug 14 can rotate and it protects the internal components of the lock 10. The cylinder 12 includes a cylindrical body portion 18 having a first internal surface 20. Extending from the cylindrical body portion 18 is a cuboid body portion 22. The cuboid body portion 22 includes a first aperture 24 through which a pair of pins, a first pin 26 and a second pin 28, and a corresponding pair of biasing members, in the form of a first spring 30 and a second spring 32 extend. This first aperture 24 extends through the whole of the cuboid body portion 22 and access into which the pins 26 and 28 and the springs are introduced into the cylinder 12, during of the lock. between the boundary of the cylinder 12 and the shear line 34 (see figure 2) . The sheer line 42 can be regarded as the junction between the internal surface 20 of the cylinder 12 and the external surface 40 of the plug 14. When the pins 26 and 28 are straddling the shear line 42, the lock 10 is considered to be in a locked condition. When in a provides the and 32 construction Located 14 is a locked condition the plug 14 is prevented from rotating within the cylinder. When the pins 26 and 28 are not straddling the shear line 42, the lock 10 is regarded as being in an unlocked condition and the plug 14 is able to rotate within the cylinder 12 . The plug 14 provides housing for a cam 36 and a motor 38 and is rotatable within the cylinder 12. The plug 14 includes an external surface 40 through which a second aperture 42 extends. The second aperture 42 aligns with the first aperture 24 through which the pins 26 and 28 can also extend when the lock 10 is in a locked condition. The plug 14 also includes a circular planar surface 46. The circular planar surface 46 includes a first recess 48 into which a first protrusion 48 engages. The first protrusion 48 is located on the keyway 16. This engagement, between the plug 14 and the keyway 16, enables rotation of the plug 14 within the cylinder 12 when the lock 10 is in an unlocked condition via the rotation of the keyway 16 after the insertion of the correct electronic key. Referring specifically now to figures 2 and 4, the first pin 26 includes a first head 50 and a first tail 52. The first head 50 includes a first surface 54 that has a diameter larger than that of a second surface 56 on the first tail 52. Making contact with this first surface 54 is one end of the first spring 30. The second surface 56 of the first tail 52 makes contact with either the cam 36 when in an unlocked condition or, when the lock 10 is in a locked condition, a portion of the second surface makes contact with the edge of the motor 38 (as seen in figure 2). The first spring 30 biases the first pin 26 towards the cam 36 (or motor 38) such that the first pin straddles the shear line 34 when in a locked condition. The opposing end of the first spring 30 makes contact with a capping plug 58. The capping plug 58 sits in an end of the first aperture 24 furthest away from the plug 14. Extending through the first pin 26 is a pin aperture 60 through which the second pin 28 extends. The second pin 28 includes a second head 62 having a curved surface 64, and a second tail 66. This curved surface 64 extends beyond the level at which the second surface 56 of the first pin 26 lies. This ensures that the curved surface 64 is always making contact with the cam 36, whether in a locked or in an unlocked condition. Making contact with a third surface 60 of the second head 62 (opposing the curved surface 64) is an end of the second spring 32. The opposing end of the second spring makes contact with the capping plug 58. The second spring 32 biases the second pin 28 towards the cam 36 such that the second pin also straddles the shear line 34 when in a locked condition. Both the first and the second pins, 26 and 28 have different weights or masses. The first pin 26 is defined as having a first mass, while the second pin is defined as having a second mass. Specifically, the first mass associated with the first pin 26 is greater than the second mass of the second pin 28, rendering the first pin comparatively heavier. This difference in mass between the two pins, 26 and 28, results in distinct oscillation frequencies, thereby enabling the pins to bounce at varying rates. Similarly, the first and the second springs 30 and 32, that control the biasing direction of the pins 26 and 28, have a unique tension associated with them. Particularly, a first tension associated with the first spring is greater than a second tension of the second spring. This results in a higher force being exerted by the first spring 30 on to the first pin 26. This discrepancy in tension between the two springs 30 and 32 leads to differential rates of compression and extension, thereby enabling the springs to react at varying rates. Controlling the position of the first and second pins, 26 and 28 is the cam 36. The cam 36 is connected to the motor 38 with its outer edge in contact with the pins, 26 and 28. When in the locked condition the cam 36 is in a first rotational position and when the lock 10 is in an unlocked condition the cam rotates to a second rotational position. The cam 28 is egg-shaped and includes a head portion 68 and tail portion 70. The cam 36 is connected to the motor 38 slightly off axis which enables the cam to vary the height of pins, 26 and 28, during a full rotation. In the unlocked condition (the second rotational position), the cam has rotated such that the head portion 68 of the cam 36 is in contact with the first and second pins, 26 and 28, such that they are lifted above the shear line 34. In the locked condition (first rotational position), the cam 36 has rotated such that the tail portion 70 is in contact with the pins, 26 and 28 have been lowered below the shear line and thus are straddling it. Located in between the cam 36 and motor 38, and the keyway 16 is an annular recess 72. This recess 72 is typically machined through the plug 14 and is characterised by its ring-like shape, with a consistent width and depth encircling a central axis 74. Located along the central axis 74 is a plug aperture 76. The annular recess 72 forms a wall 78 that acts as a sacrificial barrier. The wall 78 is located and designed to absorb and dissipate the forces applied during unauthorized attempts to manipulate or breach the lock 10. The wall 78 of the annular recess 72 includes a thickness of less than 10% of the diameter of the plug 14. This ensures that the wall 78 is thin enough to serve its sacrificial purpose effectively while still providing sufficient strength to ensure that the key can rotate the plug and to provide protection to the critical components of the lock. The method of operating the lock 10 will now be described. When the user has the correct electronic key for an associated lock 10, the user inserts that key into the keyway 16. The electronic key supplies the lock 10 with power, checks that the code provided by the key is correct and, if so, sends a voltage to the motor 38. The motor 38 activates and begins to rotate the cam 36 so that the head portion 68 of the cam moves towards the pins, 26 and 28. As the cam 36 rotates, the head portion 68 starts making contact with the curved surface 64 of the second pin 28 and the second surface 56 of the first pin 26. As the cam 36 further rotates the head portion 68 begins to lift the pins, 26 and 28, up through the first aperture 24 towards the capping plug 58 by compressing the springs 30 and 32. When rotation of the cam 36 is complete the pins 26 and 28 are raised above the shear line 34 such that they are no longer straddling it. At this stage the lock 10 is in the unlocked condition. The user can now rotate the keyway 16 that in turn rotates the plug 14 within the cylinder 12 and unlock the lock 10. The rear end 80 of the plug 14 includes a linear recess 82 which controls a latch (not shown) or the like. When the user has finished with the lock 10 a signal is sent to motor 38 again to activate the cam 36. The motor 38 rotates the cam 36 such that the tail portion 70 of the cam moves towards the pins, 26 and 28. The pins 26 and 28 begin to lower and the head portion 68 rotates away and no longer contacts the pins. Once the cam 36 has completed its rotation the curved surface 64 of the second pin 28 lowers and makes contact with the tail portion 70. Equivalently, the second surface 56 of the first pin 26 lowers and a portion of the first pin 26 makes contact with a portion of the motor 38. Both pins 26 and 28 are now positioned such that they are straddling the shear line 34 and are in a locked condition. The plug 14 at this stage can no longer rotate within the cylinder 12 and unlock the lock 10. If an intruder attempts to break the lock using a drill, the vibrations of the drill cause the first and second pins, 26 and 28 to bounce. Due to the differing masses of the pins, 26 and 28, and the varying tensions of the first and second springs, 30 and 32, the pins bounce at different rates. This discrepancy in oscillating rates prevents both pins, 26 and 28 from simultaneously aligning above the shear line 34, thereby preventing the lock 10 from being unlocked. If brute force is applied during the drilling attempt, the sacrificial wall 78 located in the plug 14 will break. The wall 78 acts as a barrier between the keyway and the plug 14 by absorbing the force applied through the drill. Eventually the wall 78 fails under excessive stress. When the sacrificial wall 78 breaks, the engagement between the keyway 16 and the plug 14 is lost. Consequently, any rotation of the keyway 16 does not result in the rotation of the plug 14, rendering the lock inoperable and effectively broken. It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the protection which is defined by the appended claims. In particular, where various embodiments and aspects of the invention have been described above, features and steps of the apparatus and method are interchangeable between the embodiments and aspects of the invention. For example, where dimensions are indicated in the examples set out above these are examples of ideal measurements but should not be taken as being indicative of being essential to the performance of the invention. In the above example the pins are described as having different mass and the spring are defined as having different tensions. Variations of the masses and tensions could also work. For example, the pins could have equal masses and the springs have different tensions or the pins could have different masses whilst the springs have equal tensions. Another example refers to the second pin extending through the aperture of the first pin. In order to maintain the combination of two pins within the same space it could also be conceived that both pins sit side by side. A further example is the thickness of the wall. It is described as having a thickness of less than 10% of the diameter of the plug. However, other thicknesses could work if it was ensured that the wall would break under unauthorised forces whilst maintaining the integrity of the lock. It should also be noted that it is not an essential feature of the invention that the second pin makes contact with the motor. In the main embodiment described above this is done for convenience due to the size of the motor within the plug. In order to fit the motor into the plug and use pins of a suitable size, the second or outer pin, contacts the motor on one edge rather than the cam. An additional example is when the pins are in a locked condition a portion of the first pin rests on the edge of the motor as seen in figure 2. The lock mechanism would also work if the first pin rested entirely on the cam when in an unlocked condition. The resting position of both pins, while in the locked condition, could be either at the edge of the motor or the cam. The critical aspect is that, when in the locked condition, the pins straddle the shear line . As the mechanism transitions to an unlocked condition, the pins eventually make contact with the rotating cam, causing them to be raised above the shear line and thus moved into the unlocked condition. A further example is the shape of the cam. In the main embodiment described above the cam is described as egg-shaped. However, other shapes of cams could be used such as eccentric / offset circular, oval, elliptical, irregular or snail / drop . - 12 -

Claims

1. A locking device comprising:a cylinder;a plug rotatable within said cylinder and defining a junction therebetween;a keyway for insertion of a key;a cam located within said plug;a motor activated by said key, for rotating said cam between a first and a second rotational position;a first pin biased towards said cam by a first biasing member; anda second pin biased towards said cam by a second biasing member wherein when in a locked condition said cam is in a first rotational position and either of said first and second pins straddles said junction thereby preventing rotational movement of said plug and when said motor is activated and said cam rotates into said second rotational position, said first and second pins move into an unlocked condition such that a surface of both said first and second pins align with said junction thereby allowing rotational movement between said plug and said cylinder .

2. A locking device according to claim 1 wherein said first pin includes a pin aperture and wherein said second pin extends into said pin aperture.

3. A locking device according to claim 2 wherein said second biasing member extends through said first biasing member.

4. A locking device according to claim 2 or 3 wherein said aperture extends through said first pin.

5. A locking device according to any preceding claim wherein said first pin includes a first mass and said second pin includesa second mass wherein, said first mass is different than saidsecond mass.

6. A locking device according to any preceding claim whereinsaid first biasing memberincludesfirsttension and saidsecond biasing member includesfirst tension is different thanA locking device accordinga second tension, wherein said said second tension.to any preceding claim, whereinsaid plug further comprises an annular recess forming a wall.

8. A locking device according to claim 6 wherein said annular10 recess further comprises a plug aperture adjacent said wall and extending through said annular recess.

9. A locking device according to any preceding claim wherein said wall includes a thickness and said plug includes a diameter wherein said thickness of said wall is less than 10% of the said 15 diameter of said plug.

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