Cylinder lock

Abstract

A cylinder lock includes a lock body 203 in which is mounted a first and second rotational bodies 201, 202, separated by a shield 202 and a plurality of pin stacks which straddle the first and second rotational bodies. There is limited free rotational movement / play between second rotational body and first rotational body. The pin stacks prevent rotation of the second rotational body unless aligned at correct position by correct key. In a first arrangement the pin stacks are radial and the rotational bodies are a concentric with central rotator 201 within an outer cylinder 204 with shield 203 between them. In an alternative arrangement the pin stacks are parallel to the rotational axis and the first and second rotational bodies are coaxial and axially offset with shield sandwiched between their ends. Preferably the pin stacks are spring biased and include working pins (intermediate pins) 210 between key pins 205, driver pins 207; the working pins corresponding to the shield, a series of plural wafer pins 211 may be included between key pins and working pins.

Description

Technical Field 1. The following disclosure relates to improvements to locks, and in particular to lock mechanisms with an improved resistance to picking. Background 2. A conventional form of lock is a pin cylinder lock, for example as shown in Figure 1 in the form of a “Euro Cylinder” lock. In such locks a key slot 100 is provided within a central rotatable body 101 into which a key is inserted to operate the lock. The central rotatable body 101 is rotatably mounted within the lock housing 102 such that rotation of the key rotates the central body 101. The central body 101 can be used to activate other mechanical devices, for example unlocking a door. Rotation of the central body 101 is prevented by a set of driver pins 103 and key pins 104, unless the correct key is inserted. If the correct key is inserted the interface 106 between each of the driver pins 103 and corresponding key pins 104 aligns with the interface 105 between the central body 101 and the housing 102 to allow rotation (the key pins 104 rotate with the central body 101 and the driver pins 103 remain static with the housing 102). If the incorrect key is inserted the height of the interface 106 between at least one of the driver pins 103 and corresponding key pins 104 will not align with the interface 105 between the central body 101 and the housing 102 and the pins 103, 104 will prevent rotation of the central body 101. The pins 103, 104 are biased towards the key slot 100 by springs 107, or other suitable resilient members. 3. Such locks can be picked by adjusting the height of the key pins using a tool in the key slot 100 such that each pin is positioned at the height required to allow rotation. Rotational torque is typically applied to the central rotatable body while adjusting the height of each pin which allows the correct position to be felt during the process. Although a skilled process it is relatively straightforward to achieve. 4. The following disclosure aims to address at least some features of conventional lock designs to improve resistance to picking. Summary of the Invention 5. This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 6. The invention is defined in the appended claims in which there is provided a lock mechanism, comprising a lock body; a central body rotatable around a lock axis relative to the lock body; a shield arranged coaxially with and outside of the central body, the shield being static relative to the lock body; an outer cylinder arranged coaxially with and outside of the shield, the outer cylinder being rotatable about the lock axis relative to the lock body, the outer cylinder also being rotatable relative to the central body within an allowable angular range relative to the central body; and at least one pin stack comprising a plurality of stacked pins, each pin stack being aligned on a pin stack axis which lies radially from the lock axis, each pin stack being within each of the central body, the shield, the outer cylinder, and the lock body, each pin being slideable along the pin stack axis; wherein each pin stack prevents rotation of the outer cylinder relative to the lock body and shield, except when the pin stack is in a single predefined position. 7. The lock mechanism may further comprise a key slot in the central body for receiving a key, wherein a key positioned in the key slot moves each pin stack to a position along the relative pin stack axis. 8. The at least one pin stack may be biased towards the lock axis, or away from the lock axis. 9. The position of the pin stack along the pin stack axis may only be changed when the central body and outer cylinder are in a home position. 10. When the outer cylinder is in the home position and the central body is rotated by the allowable angular range from the home position the position of the pin stack along the pin stack axis may not be changed. 11. The outer cylinder may comprise a bar fitting within a notch on the central body such that the central body can rotate by the allowable angular range relative to the outer cylinder before the bar engages a wall of the notch to drive the outer cylinder. 12. The lock mechanism may further comprise a home mechanism which moves the outer cylinder to the home position from a position within a predetermined angular rotation of that home position. 13. The home mechanism may comprise a detent in the outer cylinder and a pin biased towards that detent to cause rotational movement towards the home position. 14. There is also provided an axial lock mechanism, comprising a lock body; a first rotatable body rotatable around a lock axis relative to the lock body; a second rotatable body rotatable around the lock axis relative to the lock body, the second rotatable body being rotatable relative to the first rotatable body within an allowable angular range relative to the first rotatable body; a shield arranged between part of the first rotatable body and part of the second rotatable body in a direction parallel to the lock axis the shield being static relative to the lock body; and at least one pin stack comprising a plurality of stacked pins, each pin stack being aligned on a pin stack axis which lies parallel to the lock axis, each pin stack being within each of the first rotatable body, the shield, the second rotatable body, and the lock body, each pin being slideable along its pin stack axis; wherein each pin stack prevents rotation of the second rotatable body relative to the lock body and shield, except when the pin stack is in a single predefined position. 15. The axial lock mechanism may further comprise a key slot for receiving a key, wherein a key positioned in the key slot moves each pin stack to a position along the relative pin stack axis. 16.    The at least one pin stack may be biased in one of the two directions along its axis. 17.    The position of the pin stack along the pin stack axis may only be changed when the first rotatable body and second rotatable body are in a home position. 18. When the second rotatable body is in the home position and the first rotatable body is rotated by the allowable angular range from the home position the position of the at least one pin stack along the pin stack axis may not be changed. 19. The axial lock mechanism may further comprise a home mechanism which moves the second rotatable body to the home position from a position within a predetermined angular rotation of that home position. 20. The home mechanism may comprise a detent in the second rotatable body and a pin biased towards that detent to cause rotational movement towards the home position. Brief description of the drawings 21. Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. 22.    Figure 1 shows an isometric cross-section of a conventional pin cylinder lock; 23.    Figure 2 shows an isometric cross-section of a pin-cylinder lock as set out in this disclosure; 24. Figure 3 shows section through one pin stack with (a) the pin stack at the incorrect height for opening, and (b) at the correct height with the lock open; 25.    Figure 4 shows an example of a backlash mechanism; 26.    Figure 5 shows an example of a detent mechanism for moving the central rotatable body to a home position; and 27. Figure 6 shows an isometric cross-section of an axial pin lock. Detailed Description 28. Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings. 29. The following description is provided in the context of a so-called “Euro-cylinder” lock, but as will be appreciated the principles described are applicable in any appropriate lock format and the disclosure is not limited to any particular style of lock. 30. Figure 2 shows an isometric cross section of an example lock 200 according to this disclosure in a Euro-cylinder format. Lock 200 comprises a central body 201 which is rotatably mounted within coaxial shield 202. The coaxial shield 202 is static in relation to the lock body 203. In Figure 2 the coaxial shield is shown as being formed as part of the lock body 203, but it may also be a separate element fixed to the lock body. Outer cylinder 204 is rotatably mounted between coaxial shield 202 and lock body 203. As will be explained in detail below a limited amount of free relative rotation is permitted between central body 201 and outer cylinder 204, but beyond that limited amount rotation central body 201 is coupled to the outer cylinder 204 to drive the outer cylinder 204 as the central body 201 is rotated. 31. A set of key pins 205 are slideably mounted for movement along their axis (for vertical movement in the plane and orientation of Figure 2) within the central body 201 and protrude into key slot 206 to be acted on by a key in the key slot 206 in the conventional manner. Key pins 205 are individually slideable and biased by the pins above them towards the key slot. A set of driver pins 207 are slideably mounted in lock body 203. Each driver pin 207 is biased by a resilient member 208 towards the key slot 206. 32. A set of working pins 210 are slideably mounted below the driver pins 207, with one working pin 210 corresponding to one driver pin 207 and one key pin 205. such that when the lower surface of the driver pin 207 is aligned with the interface between the outer cylinder 204 and the lock body 203, the lower surface of the working pin 210 aligns with the interface between the coaxial shield 202 and the outer cylinder 204. In this position the outer cylinder 204 can rotate relative to the coaxial shield 202 and lock body 203 with the working pins rotating with the outer cylinder 204. At other heights the working pins 210 prevent rotation of the outer cylinder 204 as the working pins will span one of the rotating interfaces of the outer cylinder 204. As explained further below, the form of pins forming each pin stack described herein is a specific example only, and the pin stacks may be formed of other numbers and relative thicknesses of pins. The names used herein are for clarity of description only and do not imply any particular function, unless the names have a well-known technical meaning. 33. Below each working pin 210, and above the corresponding key pin 204, are a plurality of wafer pins 211 slideably mounted for movement along the axis of the key pins 205 and working pins 210. The key pins 205, wafer pins 211, working pins 210, and driver pins 207 form a contiguous pin stack between the key slot 206 and resilient members 208. Each pin stack is slidably mounted for vertical movement along its axis (vertical in the plane and orientation of Figure 2), and is biased towards the key slot 206 by resilient members 208. 34. In order for the central body 201 and outer cylinder 204 to rotate each pin stack must be at the correct height for interfaces between elements of the pin stack to align with interfaces between the rotating and static elements, as shown in the Figure 2. In this position the working pins 210 rotate with the outer cylinder 204 and key pins 205 and some of the wafer pins 211a rotate with the central body 201. The remaining wafer pins 211b remain static with the coaxial shield 202. As will be apparent, if the pin stack is at the incorrect height at least one of the central body 201 or outer cylinder 204 will be prevented from rotating by one of the pins lying across an interface which needs to rotate. For convenience the term “pins are aligned” will be used to describe the situation where a pin stack is at the correct height and the central body 201 can be rotated. Figure 2 shows all of the pin stacks correctly aligned such that the lock can be opened. That is, the pin stacks are at the height to which they will be driven by insertion of the correct key. 35. In contrast, Figure 3a shows a cross-section through one pin stack showing the pin stack in an unaligned position. As shown in Figure 3 the central body 201 has been partially rotated, but the outer cylinder cannot move as it is blocked by working pin 302 which is not at the correct height. As will be explained in more detail below the ability of the central body 201 to partially rotate before the outer cylinder is moved improves the pick resistance of the lock. Figure 3b shows the same pin cross section, but with the lock in the open position. The pin stack is position at the correct height to allow rotation and the central body has been rotated clockwise beyond the permitted angular rotation relative to outer cylinder. As can be seen in Figure 3b the rotation of the outer cylinder “lags” that of the central body by the permitted angular rotation, or the backlash amount. As can be seen key pins 205 and wafer pins 211a have rotated with the central body 201, wafer pins 211b have remained with the coaxial shield, working pins 210 have rotated with the outer cylinder, and driver pins 207 have remained static with the lock body. 36. Central body 201 and outer cylinder 204 are linked such that central body 201 can rotate freely by a certain amount before further rotation of the central body 201 causes rotation of the outer cylinder 204. That is, there is a defined (or allowable) amount of backlash between the two elements. In Figure 4, which shows a cross section through a lock, bar 212 is part of, or mounted to, outer cylinder 204 and passes through a notch 213 in the rear end of the central body 201. Central body 201 is thus free to rotate relative to outer cylinder 204 until the bar strikes walls of the notch 213. At that point further rotation of the central body 201 is only possible if the pins are aligned. The shape of the bar and notch define the amount of backlash between the two components. 37. The mechanism shown for permitting backlash between the central body 201 and outer cylinder 204 is an example only, and as will be appreciated any appropriate mechanism may be utilised. 38. When configured for use the outer cylinder 204 is utilised as the output of the lock to drive other elements, for example a latch. When a user inserts a correct key into the key slot 206 of central body 201 the pins are aligned and the user can rotate the central body 201 with the key. The central body 201 rotates by itself for the backlash amount and then drives rotation of the outer cylinder 204. When the correct key is inserted the pins are aligned and rotation of the outer cylinder 204 is not blocked. 39. If the incorrect key is inserted not all of the pins will be aligned and rotation of the outer cylinder will be blocked. However, the central body 201 is free to rotate by the backlash amount, as shown in Figure 3, because the geometry of the pins in the pin stacks is selected such that this is possible regardless of the pin stack height. However, the outer cylinder 204 is only unblocked with the pin stack at the correct height. In alternative designs rotation of the central body 201 may also be blocked at certain pin stack heights. However, there should be pin stack heights at which the central body can rotate but the outer cylinder cannot as it is this separate movement that improves picking resistance. 40. The backlash arrangement improves the lock’s resistance to picking because as shown in Figure 3 once the central body 201 is rotated sufficiently to apply force to outer cylinder 204 the pin stack elements in the central body 201 have moved past the pin stack opening in the coaxial shield 202 and outer cylinder 204. The backlash may also be selected to be greater than shown in Figure 3 such that the central body 201 can move its pin stack entirely past the opening in the coaxial shield 202 before driving the outer cylinder 204. However, the backlash amount should be sufficient to ensure that the pin stack height cannot be changed when the central body drives the outer cylinder. 41. Once in the location shown in Figure 3, or more rotated, it is no longer possible to adjust the height of the pins in the coaxial shield 202 and outer cylinder 204. Also, while the central body 201 is in the central position, with the pin stack aligned, it is not possible to obtain information on the correct height of the pin stack to allow rotation of the outer cylinder 204 by trial and error as the central body 201 must be rotated before it can be determined if the outer cylinder 204 is blocked. Conventional trial-and-error picking attacks with feedback from the lock cannot therefore be used to correctly position the pin stacks. 42. Due to the backlash between the central body 201 and the outer cylinder 204 the key cannot be easily used to return the outer cylinder 204 to a centralised position for removal of the key. An arrangement may therefore be provided to return the outer cylinder 204 to the centralised position. Figures 2 and 5 show an example mechanism in which a detent pin 214 is resiliently biased into a shaped track 215 on the outer surface of the outer cylinder 204. When the outer cylinder 204 is moved close to the centralised position the detent pin 214 moves the cylinder to the centralised position and provides a retaining force to retain the outer cylinder 204 in that position. The arrangement of Figure 5 is an example only and any appropriate mechanism may be utilised to assist in return the outer cylinder 204 to the centralised location. 43. The lock shown in Figures 2 to 5 utilises an arrangement of a central rotatable body and outer cylinder, separated by a coaxial shield, to improve resistance to lock picking. The central rotatable body and outer cylinder are connected to allow a defined or allowable amount of backlash between them and to transfer further rotational movement from the central body to the outer cylinder. A plurality of pin stacks are provided which pass through the lock body, outer cylinder, coaxial shield, and central body such that they are movable axial to an axis of rotation of the central body and outer cylinder. The height of each pin stack can only be changed when the central body and outer cylinder are in a central position. Each pin stack prevents rotation of at least the outer cylinder when the pin stack is not in the correct height position. 44. The lock shown in the figures has been described with reference to each pin stack comprising a set of pins with specific names. These are used for example only and for convenience of description. The number and relative height of each of the pins is shown for example only. The number of pins in each stack, and their relative heights, can be selected to provide the required performance and behaviour. As explained above, each pin stack should be designed such that the outer cylinder can only rotated when the pin stack is at a single correct height. At that height the central body must also be able to rotate. At other heights the central body should be able to rotate as this rotation at incorrect heights contributes to the lock’s resistance to picking. In an example, the working pins may be thinner than described and additional wafer (i.e. thin) pins may be positioned between the working pins and driver pins. The pin stack can be generalised as a plurality of pins forming a pin stack, wherein the pins are movable along the pin stack axis and have a single position where they do not prevent rotation of the outer cylinder. 45. Additional coaxial shields and outer cylinders can be utilised to provide further protection. That is, a further coaxial shield can be position outside of the outer cylinder, with a further outer cylinder connected with an allowable backlash to the outer cylinder. The further outer cylinder forms the output of the lock. 46.    In a variation the pin stacks may be biased away from the lock axis by resilient elements. 47.    The principles embodied by the description hereinbefore may also be applied to devices with lateral, rather than rotational movement. 48. The same principles apply to an axial pin lock / tubular lock. In such locks the pin stacks are parallel to the axis of rotation of the central body in which the key is inserted. Such a lock is shown in Figure 6. In such a lock according to the present disclosure the shield 602 is an element perpendicular to the axis of rotation of the central body 601 separating the central body from a further rotatable body 603. The pin stacks are as described hereinbefore but are aligned with the axis. An allowable backlash is provided between the central body 601 and further rotatable body 603 to provide the same functionality described hereinbefore for the central rotatable body and the outer cylinder, but with the elements rotating on a common axis. When the central body is in the home position the pin stack positions can be adjusted, but once the central body has been rotated by the allowable backlash the positions can no longer be adjusted. 49. In the general sense the lock comprises a first element and a second element mechanically coupled to permit limited relative movement before further movement of one element causes movement of the other element. The first and second elements are separated by a shield component. At least one pin stack passes through the first and second elements, and the shield, such that movement of the second element is only possible with each pin stack at the correct height. The pin stack height can only be varied with the first and second elements in a home position. When the first and second elements are positioned relative to each that one element can drive the other element the pin stack height cannot be changed. 50. References in this disclosure to pin stack height are intended to refer to the position of the pin stack along an axial direction from the axis of the central body, “lower” is towards the axis and “higher” is away from the axis. 51. Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to ‘a’, ‘an’, ‘first’, ‘second’, etc. do not preclude a plurality. 52. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ or “including” does not exclude the presence of other elements.

Claims

1. A lock mechanism, comprisinga lock body;a central body rotatable around a lock axis relative to the lock body;a shield arranged coaxially with and outside of the central body, the shield being static relative to the lock body;an outer cylinder arranged coaxially with and outside of the shield, the outer cylinder being rotatable about the lock axis relative to the lock body, the outer cylinder also being rotatable relative to the central body within an allowable angular range relative to the central body;at least one pin stack comprising a plurality of stacked pins, each pin stack being aligned on a pin stack axis which lies radially from the lock axis, each pin stack being within each of the central body, the shield, the outer cylinder, and the lock body, each pin being slideable along its pin stack axis;and a key slot in the central body for receiving a key, wherein a key positioned in the key slot moves each pin stack to a position along the relative pin stack axis;wherein each pin stack prevents rotation of the outer cylinder relative to the lock body and shield, except when the pin stack is in a single predefined position.

2. The lock mechanism of claim 1, wherein the at least one pin stack is biased towards the lock axis, or away from the lock axis.

3. The lock mechanism of any preceding claim, wherein the position of the pin stack along the pin stack axis can only be changed when the central body and outer cylinder are in a home position.

4. The lock mechanism of claim 3, wherein when the outer cylinder is in the home position and the central body is rotated by the allowable angular range from the home position the position of the at least one pin stack along the pin stack axis cannot be changed.

5. The lock mechanism of any preceding claim, wherein the outer cylinder comprises a bar fitting within a notch on the central body such that the central body can rotate by the allowable angular range relative to the outer cylinder before the bar engages a wall of the notch to drive the outer cylinder.

6. The lock mechanism of any preceding claim further comprising a home mechanism which moves the outer cylinder to the home position from a position within a predetermined angular rotation of that home position.

7. The lock mechanism of claim 6, wherein the home mechanism comprises a detent in the outer cylinder and a pin biased towards that detent to cause rotational movement towards the home position.

8. A lock mechanism, comprisinga lock body;a first rotatable body rotatable around a lock axis relative to the lock body;a second rotatable body rotatable around the lock axis relative to the lock body, the second rotatable body being rotatable relative to the first rotatable body within an allowable angular range relative to the first rotatable body;29 08 24a shield arranged between part of the first rotatable body and part of the second rotatable body in a direction parallel to the lock axis the shield being static relative to the lock body;at least one pin stack comprising a plurality of stacked pins, each pin stack being aligned on a pin stack axis which lies parallel to the lock axis, each pin stack being within each of the first rotatable body, the shield, the second rotatable body, and the lock body, each pin being slideable along its pin stack axis; anda key slot for receiving a key, wherein a key positioned in the key slot moves each pin stack to a position along the relative pin stack axis;wherein each pin stack prevents rotation of the second rotatable body relative to the lock body and shield, except when the pin stack is in a single predefined position.

9. The lock mechanism of claim 8, wherein the at least one pin stack is biased in one of the two directions along its axis.

10. The lock mechanism of any of claims 8 or 9, wherein the position of the pin stack along the pin stack axis can only be changed when the first rotatable body and second rotatable body are in a home position.

11. The lock mechanism of claim 10, wherein when the second rotatable body is in the home position and the first rotatable body is rotated by the allowable angular range from the home position the position of the at least one pin stack along the pin stack axis cannot be changed.

12. The lock mechanism of any of claims 8 to 11 further comprising a home mechanism which moves the second rotatable body to the home position from a position within a predetermined angular rotation of that home position.

13. The lock mechanism of claim 12, wherein the home mechanism comprises a detent in the second rotatable body and a pin biased towards that detent to cause rotational movement towards the home position.

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