GB2494620A - Thumb turn mechanism for a cylinder lock - Google Patents

Abstract

A cylinder lock 10 with exterior lock actuator 12; interior lock actuator 14; a cam 16 disposed between the actuators, the cam being selectively rotatable between a locked and unlocked position; the interior lock actuator 14 being driven by a thumb turn 84, the thumb turn 84 having a first position in which the cam is in the locked position and a second position in which the cam is in the unlocked position, and the thumb turn being configured to return to the first position when released. The means for returning the thumb turn 84 to its first position may be its own weight and/or due to the action of a bias by a resilient member, for example a spring 76. The arrangement may include a helical surface 82 and pin 81.

Description

Cylinder lock having a thumb turn mechanism The present invention is concerned with a cylinder lock having a thumb turn mechanism. More specifically, the present invention is concerned with a cylinder lock having a thumb turn mechanism, which cylinder lock utilises a locking clutch mechanism.

The applicant's prior published patent application, WO 2009/15673 1 (hereby incorporated by reference where permitted) discloses a cylinder lock in which a three position clutch is provided. Specifically the clutch is ananged to engage in a first position in which the interior lock actuator can rotate the lock cam, a second position in which the exterior actuator can rotate the lock cam, and a third over-travel position in which the clutch prevents the lock cam from rotating by forming a rotational load path to the interior lock actuator (which cannot rotate without a key present). The over-travel position is only entered upon removal of a component for a lock, more specifically, the exterior actuator. Therefore attempted forcing of the lock by removal of the exterior actuator prevents the intruder manually manipulating the cam.

The above referenced cylinder lock has an interior and exterior clutch component, which are in abutment via a shaft projecting through the centre of the cam. When a key is inserted from the exterior side, the exterior clutch component is advanced towards the interior side and engages a formation on the cam. At the same time the interior clutch component is pushed out of engagement with the cam by the shaft.

This results in the cam being rotationally engaged with the exterior lock actuator, and turning the key will rotate the cam to open the lock.

Conversely, insertion of a key from the interior will engage the interior clutch member with the cam (although the clutch is usually biased to engage the interior mechanism anyway).

Therefore the relevant clutch component can only engage the cam if the cam is in a locked position. Only then can the clutch component and the cam engage. This is normally the case with a cylinder lock having two keys, because the opposite lock actuator must be in a locked position in order to remove the key anyway. In effect, the use of a key on the interior side ensures that the lock cam will be left in the locked position (assuming that the key is always removed by the user).

It is desirable to provide lock cylinders which utilise the above referenced security mechanism, but also feature a thumb turn for ease of unlocking from the interior side of the closure. A potential problem with a thumb turn mechanism is that it may easily be left in a position other than the locked condition because there is no key to remove.

Under these circumstances, a key cannot be inserted from the lock exterior because the relevant slot in the cam will be out of alignment with the exterior clutch component.

Some prior art locks utilise a compressible clutch in order to overcome this problem.

Under these circumstances the exterior key can be inserted and the clutch is compressed without engaging the formation on the cam. The key is then rotated until the compressible clutch resiles and "snaps" into the cam formation.

A ffirther problem with using a thumb turn as an interior actuator is that most thumb turn mechanisms can be back-driven from the cam, which means that the cam can be rotated by an intruder even when rotationally fixed with the interior lock actuator.

It is an aim of the present invention to overcome, or at least mitigate, the above mentioned problem.

According to the invention, there is provided a cylinder lock comprising: an exterior lock actuator, an interior lock actuator, a cam disposed between the interior and exterior lock actuators, the cam being selectively rotatable by the first and second lock actuators between a locked position and an unlocked position, in which the interior lock actuator is driven by a thumb turn, the thumb turn having a first position in which the cam is in the locked position and a second position in which the cam is in the unlocked position, wherein the thumb turn is configured to return to the first position when released by a user.

Advantageously, allowing the thumb turn to return to a first position by default, means that absent user interaction, the cam will always be in a frilly locked position and therefore the user will be able to engage a key on the exterior side of the lock mechanism.

The thumb turn may be resiliently biased to the first position, for example by a resilient member arranged to resiliently bias the thumb turn to the first position. The resilient member may be a spring. Provision of a sprung system allows fast and reliable return of the cam to the locked position, and the spring may be selected to overcome any expected frictional forces experienced. This method used in isolation also allows for standard (e.g. rotationally symmetrical) thumb turn members to be used.

Preferably the resilient member is a compression spring acting on a mechanism arranged to convert the linear motion of the spring to rotational motion of the cam.

This is a "gear" type mechanism in which the gearing may be provided by a surface simultaneously advancing along and circumscribing a lock axis, in which the surface is engaged by a pin. The surface may be defined on a groove which slidably receives the pin.

Preferably the surface or groove describes a helical path, and more preferably the surface or groove describes two minor-image helical paths to form an endless surface or groove.

The mechanism may comprise a shaft, in which the surface or groove is defined on an outer surface of the shaft and the pin projects inwardly against the surface or into the groove. The pin may project ftDm a separate bush or directly into the groove from the lock barrel.

The interior lock actuator gcncrally comprises a clutch mcmbcr. The shaft is rotationally fixed but translationally movable relative to a housing in which the clutch member sits. Thereibre any translational motion of the shaft is not transmitted to the clutch member, only the rotational motion.

Preferably the clutch member is resiliently biased away from the shaft, i.e. into engagement with the cam.

Additionally, or alternatively to a spring biased thumb turn, the thumb turn may comprise a member rotatably mounted about an actuation axis of thc interior actuator, wherein the mass of the member is distributed such that the lever returns to the first position when released by a user. The member may comprise a lever arm.

Advantageously, providing a thumb turn member which is weighted to return to the delimit first position is a simple and inexpensive way of achieving the above mentioned aim. The thumb turn is weighted such that it returns to a single rotational position only.

An example cylinder lock according to the present invention will now be described with reference to the following figures:-FIGURE 1 is an exploded perspective view of a cylinder lock in accordance with the present invention; FIGURE 2 is an perspective view of the lock of Figure 1 in an assembled condition; FIGURE 3 is a reverse angle exploded perspective view of the lock of Figure 1; Figures 4a to 4c are underside views ofa part ofthe lock ofFigure 1 in a series of positions in use; and, Figures 5a to Sc are underside views of a part of an alternative lock of the present invention in a scrics of positions in use.

Turning to the Figures, a cylinder lock 10 comprises an exterior actuator assembly 12 and an interior actuator assembly 14. A cam 16 and a shackle 18 arc disposed between the exterior and interior actuator assemblies 12, 14.

Turning to the external actuator assembly 12, an exterior actuator assembly barrel 20 is provided which contains an exterior lock plug 22 rotatably mounted therein. A lock pin housing 24 extends radially from the barrel 20 and comprises an assembly of key and driver pins (as known in the art). The plug 22 is configured to receive a key 26, which actuates the pins contained within the lock pin housing 24 in order to permit rotation of the plug 22. Insertion of the key 26 also causes movement of an exterior actuator assembly clutch member 28 in an axial direction towards the interior actuator assembly 14, as will be discussed below.

Between the exterior and interior actuator assemblies 12, 14, the cam 16 is mounted for rotation about a main axis A of the lock 10. The cam 16 comprises a cam shaft 30 and a cam lever 32 which, in use, is connected to a lock mechanism of a door to lock and unlock it.

The cam shaft 30 comprises a radially extending clutch lock pin hole 34 for engagement by a clutch pin as will be described below.

The shackle 18 comprises a central fixing member 36 by which means the cylinder lock 10 is attached to a closure via a boh 37, and further comprises a first leg 38 and a second leg 40 in order to attach the shackle 18 to the exterior and interior actuator assemblies 12, 14 respectively.

The fixing member 36 defines a recess 39 to allow passage of the cam lever 32. The fixing member 36 also extends up to the cam shaft 30 on the exterior side for additional security (i.e. to block access to the cam if the exterior actuator assembly 12 is removed by force).

Turning to the interior actuator assembly 14, an interior actuator lock barrel 42 is provided, defining a radial protrusion 44. The band 42 is generally cylindrical having a cylindrical through bore 46 in line with the axis A of the lock 10.

The protrusion 44 comprises a blind bore 48 extending offset from and parallel to the axis A, sized to receive the second leg 40 of the shackle 18 and for attachment thereto.

The protrusion 44 further comprises a pair of radial through bores 47, 50. It will be noted that the radial through bores 47, 50 are the endmost key / driver pin bores within the protrusion 44. A pair of radial pins 49, 51 are provided which engage the radial through bores 47, 50 to project into the bore 46 of the band 42 for reasons which will be describe below.

The interior actuator assembly 14 further comprises a clutch housing 52 which is mounted for rotation within the bore 46 of the barrel 42. The clutch housing 52 is cylindrical, having a bore 53 defined in a first end which includes an axial slot 54 defined in a wall thereof and a radial clutch pin bore 56 at 90 degrees to the slot 54.

The clutch housing 52 defines a circumferential groove 58 spaced from the first end.

The clutch housing 52 defines a shoulder 60 at a second end which steps down to a stub shaft 62 defining an axial bore 64 having a flat 66. When assembled, the radial pin 49 projects through the bore 47 into the groove 58 of the clutch housing 52 to translationally (but not rotationally) constrain it relative to the barrel 42.

A shouldered bush 68 is provided which sits within the band 42 and is fixed thereto.

The shoulder bush 68 comprises a first portion 70 having a lesser diameter and a second portion 72 having a greater diameter. The portions are separated by a shoulder 74. The shouldered bush defines an axial through bore 69, which received the stub shafi 62 in use. The bush 68 also has a groove engaging pin 81 projecting from its sidewall into the bore 69 in the region of the second portion 72.

The bush 68 is held in position within the bore 46 of the barrel 42 by engagement with the radial pin 51 projecting through the bore 50.

The internal actuator assembly 14 frirther comprises a helical compression spring 76 which is arranged to sit within the shouldered bush 68 and abut the shoulder 60 of the clutch housing 52, receiving the stub shaft 62.

A helical pin 78 is provided, having a minor shaft 80 at a first end, being cylindrical and comprising a flat formed thereon to so as to be rotationally fixed but slidably received within the bore 64 in the stub shaft 51. The helical pin 78 has a major shaft 79 defining a groove 82 comprising two mirror image helical sub-grooves which meet at each end to form an endless groove. The sub-grooves meet at a first position 91 on top of the shaft 79 and a second position 95 at 180 degrees to the first position 91. At the second position 95 an axial slot 97 extends from the groove 82 where the sub-grooves meet.

The major shaft 79 and minor shaft 80 are separated by a shoulder 83 The groove 82 is therefore oriented at an oblique angle to the axis A in use. When inserted into the bush 68, the pin 78 can rotate and Uanslate therein, but motion is constrained by the engagement of the groove engaging pin 81 into the groove 82. Therefore rotation of the helical pin 78 results in translation, and vice versa. In other words, the motion of the pin 78 is generally helical.

A thumb turn member 84 is provided rotationally fixed to the helical pin 78 via a pin 86. The member 84 comprises a shaft 88 and an axially projecting lever 90. The lever 90 is integral with the shaft 88 at a first end, is eccentric and contains most of its weight at a second end opposite shaft 88.

At the opposite end of the clutch housing 52 to the stub shaft 62 an interior side clutch member 92 is provided. The interior side clutch member 92 defines a radial tab 93 which engages with the slot 54 in the clutch housing 52 so as to be rotationally (but not translationally) fixed thereto. A compression spring 94 sits within the bore 53 of the clutch housing 52, and bears against the end of the bore 53. The spring 94 resiliently biases the clutch housing 52 and clutch member 92 apart.

Thc tab 93 of the clutch mcmbcr 92 is selectively engageablc with a formation (not shown) on the interior of the cam 16. As mentioned above, upon insertion of the key 26, the exterior clutch member 28 can push and disengage the interior clutch member 92 from the cam 16 by compressing the spring 94 along the axis A. The interior clutch member 92 further comprises a spring 96 which biases a locking clutch pin 98 radially outwardly for selective engagement with the clutch pin bore 56 in the clutch housing 52 and through to the lock pin hok 34 in the cam 16.

Inusc, the cylinder lock 10 opcratcs as follows:-Without a key in the exterior actuator assembly 12, the exterior clutch member 28 is in a position such that thc interior clutch mcmbcr 92 is engaged with the cam 16. It will be noted that in normal use, the interior clutch member 92 has not progressed far enough towards the exterior actuator assembly 12 to engage the pin 98 in the bore 34 (and the bore 56). Therefore the spring 94 is still somewhat compressed under these circumstances.

As shown in Figure 4a, the pin 81 sits within the axial slot 97 when the thumb turn is in the locked condition. This has the effect of locking the helical pin (and hence the thumb turn) against rotation.

In order to turn the thumb turn mcmbcr 90, the user first needs to prcss it into the lock cylinder to compress the spring 76 and move the helical pin 78 such that the pin 81 clears the axial slot 97 and moves into the helical slot 82.

Only then can the thumb turn member 90 and the helical pin 78 be rotated. As the helical pin 78 rotates, the engagement of the groove engaging pin 81 with the helical groove 82 will cause both the member 90 and the helical pin 78 to be drawn towards the barrel 42 along the axis A. This is shown in the movement from Figure 4b to Figure 4c. As this occurs, spring 76 is comprcsscd. Because the shaft 80 is cngagcd with the bore 64 and they cannot relatively rotate due to the existence of the corresponding flats, thc clutch housing 52 rotates, which rotation is transfcncd to the clutch member 92 and hcncc to thc cam 16 to unlock the lock.

Once the closure has been opened and closed, the lever 90 is released. Due to the pre-compression of the spring 76, the helical pin 78 is pushed outwardly towards the interior. As this occurs, the helical groove 82 converts this axial motion to rotational motion thus returning the lever 90 to the position shown in Figures 1, 3 and 4a. When the pin 81 and the axial slot 97 align in the position shown in Figure 4b, the helical pin 78 will "snap back" and the pin 81 and the slot 97 again become engaged.

Because the lever 90 retums to the default (locked) position, the cam 16 is also always returned to a locked position. As such, if a key 26 is inserted from the exterior actuator assembly, the exterior clutch member 28 pushes the interior clutch member 92 away from the cam 16 under the bias of spring 94. As the interior clutch member 92 is pushed out of engagement with the cam 16, the drive between the lever 90 and the cam 16 is broken. As this occurs, the exterior clutch member 28 engages the cam 16 and the lock can be opened from the exterior without causing rotation of the lever 90.

Per the applicant's previous application, should the exterior lock actuator 12 be removed, the removal of the clutch member 28 on the exterior side will allow the interior clutch member 92 to progress further towards the exterior of the lock, thus engaging the clutch pin 98 with the bores 34 and 56 under the bias of the spring 96.

This has the effect of locking the clutch, such that it is engaged with both the cam and the thumb turn assembly. Any attempts by and intruder to manually manipulate the earn will fail, because it is now rotatably fixed to the helical pin 78. As shown in Figure 4a, the groove engaging pin 81 is engaged within the axial slot 97 and as such any attempts to rotate the helical pin 78 will fail. In other words, the axial slot 97 ensures that the helical pin 78 cannot be back driven from the exterior side of the lock, it can only be rotated once the thumb turn member 90 has been depressed to free the pin am the axial slot 97.

Turning to Figures 5a to 5c, a similar helical pin 178 to the pin 78 is shown, in which the helical groove 82 is replaced by a helical surface 182. Although this means that the pin 81 is unconstrained in one direction (and therefore the user can push the helical pin 178 into the lock without being constrained to the path of the groove 82), the helical pin 178 has the same return effect as the helical pin 78 due to the engagement of the pin 81 on the helical surface 182 under the influence of the spring 76 (not shown). The helical pin 178 is easier to manufacture by casting than the pin 78, as grooves are difficult to cast (but may be machined).

Variations fall within the scope of the present invention. For example, the lever shown may be weighted to return the mechanism to the default position without using the helical pin and spring (gravity only embodiment).

Alternatively, the lever may be a standard symmetrical thumb turn arrangement in which only the bias of the spring against the helical pin will turn the thumb turn to its default position (spring bias only embodiment).

Claims (1)

1. <claim-text>Ctaims 1. A cylinder lock comprising: an exterior lock actuator, an interior lock actuator, a cam disposed between the interior and exterior lock actuators, the cam being selectively rotatable by the first and second lock actuators between a locked position and an unlocked position, in which the interior lock actuator is driven by a thumb turn, the thumb turn having a first position in which the cam is in the locked position and a second position in which the cam is in the unlocked position, wherein the thumb turn is configured to return to the first position when released by a user.</claim-text> <claim-text>2. A cylinder lock according to claim 1 in which the thumb turn is resiliently biased to the first position.</claim-text> <claim-text>3. A cylinder lock according to claim 2 comprising a resilient member arranged to resiliently bias the thumb turn to the first position.</claim-text> <claim-text>4. A cylinder lock according to claim 3 in which the resilient member is a spring.</claim-text> <claim-text>5. A cylinder lock according to claim 4 in which the resilient member is a compression spring acting on a mechanism arranged to convert the linear motion of the spring to rotational motion of the cam.</claim-text> <claim-text>6. A cylinder lock according to claim 5 in which the mechanism comprises a surface simultaneously advancing along and circumscribing a lock axis, in which the surface is abutted by a pin.</claim-text> <claim-text>7. A cylinder lock according to claim 6 comprising a groove at least partially defined by the surface.</claim-text> <claim-text>8. A cylinder lock according to claim 6 or 7 in which the surface describes a helical path.</claim-text> <claim-text>9. A cylinder lock according to claim 8 in which the surftce describes two mirror-image helical surfaces to lbrm an endless surface.</claim-text> <claim-text>10. A cylinder lock according to any of claims 6 to 9 in which the mechanism comprises a shaft, in which the surface is defined on an outer surface of the shaft and the pin projects inwardly towards the shaft.</claim-text> <claim-text>11. A cylinder lock according to claim 10 in which the interior lock actuator comprises a clutch mcmbcr, and in which the shaft is rotationally fixed but translationally movable relative to the clutch member.</claim-text> <claim-text>12. A cylindcr lock according to claim 11 in which the clutch membcr is rcsilicntly biased away flvm the shaft.</claim-text> <claim-text>13. A cylinder lock according to any of claims 6 to 12 in which the mechanism defines an axial slot arranged to receive the pin in an axial direction when the thumb turn is in the first position.</claim-text> <claim-text>14. A cylinder lock according to claim 13 in which the pin is moved from the axial slot to contact with the surface upon depression of the thumb turn into the cylinder lock.</claim-text> <claim-text>15. A cylinder lock according to any preceding claim in which the thumb turn is configured so as not to be capable of being back driven from the cam.</claim-text> <claim-text>16. A cylinder lock according to claim 13 in which the thumb turn is configured such that is cannot be rotated without being depressed into the cylinder lock.</claim-text> <claim-text>17. A cylinder lock according to any preceding claim in which thc thumb turn couugises a member mtatably mounted about an actuation axis of the interior actuator, whcrcin thc mass of the member is distributed such that the lever returns to the first position when released by a user.</claim-text> <claim-text>18. A cylinder lock according to claim 17 in which the member comprises a lever attn.</claim-text> <claim-text>19. A cylinder lock as hereinbefore described with reference to, or in accordance with, the figures.</claim-text>