Lock assembly

Abstract

 A lock assembly comprises a casing (1), a locking bolt (2) movable between an extended, locking, position in which the locking bolt projects out of the casing and a retracted, released, position, a drive including a drive member (14) for driving the locking bolt (2) into the retracted, released, position, and a coupling member (6) adjustable between a first state in which the coupling member is effective to transmit the drive from the drive member (14) to the locking bolt (2) to move the locking bolt from the extended, locking, position into the retracted, released, position, and a second state in which the coupling member is not effective to transmit drive from the drive member to the locking bolt. The coupling member (6) is biased into the second state but is arranged to adopt the first state when the locking bolt (2) is in the extended, locking, position and to remain in the second state as the drive member (14) drives the locking bolt into the retracted, released, position. The assembly further includes an auxiliary bolt 10 which is mounted in the casing for movement between an extended position in which the auxiliary bolt projects out of the casing and a retracted position, and a bolt retaining device (11) for retaining the locking bolt (2) in its retracted, released, position, when the auxiliary bolt (10) is in its retracted position.

Description

[0001] This invention relates to a lock assembly, and in particular, but not exclusively, to an electrically operable lock assembly.

[0002] In an electrically operated lock, it is known to provide a drive such as an electric motor to drive a locking bolt between an extended, locking, position in which the bolt projects out of a casing of the lock to perform a locking function, and a retracted, released, position in which the bolt is contained within the casing. Whilst it is important to be able to drive the locking bolt reliably and therefore a reliable coupling between the drive and the locking bolt is required, it is also desirable that in the event of a power failure or the like the coupling does not prevent the bolt still being moved to the extent desired.

[0003] Especially when an electrically operated lock is employed it may be desirable to ensure that when the bolt is moved from the extended, locking, position into the retracted, released, position it is held in that position until the door (or other device) is opened. Otherwise, there is a possibility of the door inadvertently being locked again before it has been opened.

[0004] It is an object of the invention to provide an improved lock assembly.

[0005] According to a first aspect of the invention there is provided a lock assembly comprising
a casing,
a locking bolt movable between an extended, locking position in which the locking bolt projects out of the casing and a retracted, released, position,
a drive including a drive member for driving the locking bolt into the retracted, released, position, and
a coupling member adjustable between a first state in which the coupling member is effective to transmit the drive from the drive member to the locking bolt to move the locking bolt from the extended, locking, position into the retracted, released, position, and a second state in which the coupling member is not effective to transmit drive from the drive member to the locking bolt, the coupling member being biased into the second state but being arranged to adopt the first state when the locking bolt is in the extended, locking, position and to remain in the second state as the drive member drives the locking bolt into the retracted, released, position.

[0006] By providing a coupling member that in a first state is effective to transmit the drive from the drive member to the locking bolt but which in a second state is not effective to do that, it becomes possible to ensure that the coupling does not prevent the locking bolt still being moved to the extent desired.

[0007] The invention is of particular relevance to the case where the drive is an electrically operated drive since such a drive is vulnerable to a power failure. In such a case the lock assembly preferably further includes a manually operable drive for driving the locking bolt into the retracted, released, position. Such a manually operable drive may be operable by a key. The key may be used to operate a mechanical lever lock, for example a 5 lever lock.

[0008] The first mentioned drive is preferably a rotary drive. In an embodiment of the invention described below the drive member comprises a post projecting from a drive wheel. The post projects from a peripheral part of the drive wheel in a direction parallel to the axis of rotation of the wheel. The wheel has a toothed circumference and is driven by an electric motor via a worm gear

[0009] The coupling member is preferably mounted on the locking bolt and is more preferably pivotally mounted on the locking bolt, pivotal movement of the coupling member moving it between the first and second states. The range of pivotal movement of the coupling member on the locking bolt is preferably limited to less than 30 degrees. In an embodiment of the invention described below the range of movement is about 15 degrees. The coupling member may be pivotally mounted on the locking bolt at one location and at another location a pin on the locking bolt or the coupling member may engage in an arcuate slot in the other of the locking bolt and coupling member to limit the range of pivotal movement. In the embodiment described below the pin is on the bolt and the slot is in the coupling member.

[0010] It should be understood that, although certain parts, for example, the coupling member, are described as "members" and may consist of a single part only, it is also possible for a "member" to comprise a plurality of parts connected together.

[0011] The coupling member may be biased into the second state by a spring but in the embodiment of the invention described below it is biased by gravity.

[0012] When the locking bolt is in the extended, locking, position, a stop member preferably engages the coupling member to hold it against its bias in the first state. The stop member may have a camming surface for engaging a follower surface on the coupling member to move it from the second state into the first state as the locking bolt is moved into the extended, locking, position.

[0013] In the description above, reference is made to the drive being for driving the locking bolt into the retracted, released, position. It is within the scope of the invention for the drive also to be able to drive the locking bolt via the coupling member into the extended, locking, position but in the preferred embodiment of the invention, the locking bolt is resiliently biased into the extended, locking, position and the drive is operable to drive the locking bolt via the coupling member in one direction only, namely into the retracted, released, position.

[0014] The locking bolt may be mounted in the casing for linear movement between its extended, locking, position and its retracted, released, position.

[0015] Preferably the lock assembly further includes
an auxiliary bolt which is mounted in the casing for movement between an extended position in which the auxiliary bolt projects out of the casing and a retracted position, and
a bolt retaining device for retaining the locking bolt in its retracted, released, position, when the auxiliary bolt is in its retracted position.

[0016] By providing an auxiliary bolt (which may also be referred to as a snib) and a bolt retaining device of the kind defined, it is possible to eliminate or at least substantially reduce the risk of a lock assembly on a door being inadvertently returned from a released condition to a locked condition before the door has been opened.

[0017] It should be understood that where reference is made herein to an "auxiliary bolt", that bolt does not necessarily have any locking or latching function (although it may do), but is intended to act as a mechanical feeler element that moves in use in response to opening and closing of a door or other device to which the assembly is fitted.

[0018] The bolt retaining device preferably includes a retaining member for engaging the locking bolt in its retracted, released, position.

[0019] The retaining member, which may be a ball, is preferably movable between a first, retaining, position for retaining the locking bolt in its retracted, released, position and a second position for allowing the locking bolt to move out of its retracted, released, position.

[0020] Preferably, when the auxiliary bolt is in its retracted position, the retaining member is resiliently biased into its first, retaining, position. That does not mean that the retaining member is necessarily in its first, retaining, position, but merely that the resilient bias towards that position is present. The resilient bias may be present at all times but it is preferred that it only takes effect or only takes its greatest effect as the auxiliary bolt is moved into its retracted position.

[0021] When the auxiliary bolt is in its retracted position, the retaining member is in its first retaining position and the locking bolt is in its retracted, released, position, the locking bolt is preferably held in its retracted, released, position, and more preferably is unable to move out of its retracted, released, position, until the auxiliary bolt moves towards its extended position. Such an arrangement prevents the locking bolt from moving out of its retracted, released, position once it has been moved to that position until the door (or other device on which the lock assembly is mounted) is opened. Such an arrangement is especially useful when a door is electrically operated to prevent the locking bolt moving back out of its retracted, released, position during any time interval that may occur before the door is opened by its electrical power.

[0022] In an embodiment of the invention described below, the bolt retaining device includes a first part mounted for movement with the auxiliary bolt and a second part whose movement causes the movement of the retaining member, the first and second parts being coupled by a resilient coupling. The first and second parts are arranged for linear movement and the coupling between the first and second parts includes a compression spring.

[0023] The feature of providing the auxiliary bolt and bolt retaining device is itself a novel feature of a lock assembly and may be employed, according to a second aspect of the invention, in a lock assembly that does not have the special drive and coupling arrangement of the first aspect of the invention. Thus according to a second aspect of the invention, there is provided a lock assembly comprising
a casing,
a locking bolt movable between an extended, locking, position in which the locking bolt projects out of the casing and a retracted, released, position,
an auxiliary bolt which is mounted in the casing for movement between an extended position in which the auxiliary bolt projects out of the casing and a retracted position, and
a bolt retaining device for retaining the locking bolt in its retracted, released, position, when the auxiliary bolt is in its retracted position.

[0024] The lock assembly according to the second aspect of the invention may have any of the features described above with reference to the first aspect of the invention, whether or not the assembly includes the drive and coupling member according to the first aspect of the invention. Thus, for example, the assembly according to the second aspect of the invention may include an electrically operated drive for driving the locking bolt into the retracted, released, position (and/or into the extended, locking, position); and the locking bolt may be resiliently biased into the extended, locking, position.

[0025] The present invention further provides a door fitted with a lock assembly as defined above. The present invention still further provides a doorway including a door as just defined and a door frame.

[0026] By way of example, an embodiment of the invention will now be described with reference to the accompanying schematic drawings, in which:

Fig. 1 is a side view of a lock assembly with a part of the casing removed to show parts of the assembly, with a locking bolt of the assembly in an extended, locking, position and with an auxiliary bolt of the assembly also in an extended position;

Fig. 2 is a side view of the lock assembly of Fig. 1, with the locking bolt of the assembly in a retracted, released, position and with the auxiliary bolt of the assembly still in the extended position of Fig. 1;

Fig. 3 is a side view of part of the lock assembly of Figs. 1 and 2, with the locking bolt of the assembly in the extended, locking, position and with the auxiliary bolt of the assembly in a fully extended position; and

Fig. 4 is a side view of part of the lock assembly of Figs. 1 and 2, with the locking bolt of the assembly in the retracted, released, position and with the auxiliary bolt of the assembly in a partly retracted position.

[0027] The drawings show a lock assembly which in this particular example is designed for a high security application such as locking the door of a prison cell. Many of the features of the lock assembly are conventional and will not be described in detail herein, but special features of the lock assembly that embody aspects of the present invention are described below.

[0028] The lock assembly shown in the drawings generally comprises a casing 1, a locking bolt 2, a drive wheel 3, a worm gear 4, drivable by an electric motor 5, a coupling member 6, a solenoid 7, a five lever lock 8, an auxiliary bolt 10 and a retaining device 11.

[0029] The locking bolt 2 is slidably mounted in the casing 1 for linear movement between an extended, locking, position in which it engages in an opening in a door frame (not shown) when the door is closed to lock the door and a retracted, released, position in which it is contained within the casing 1 and the door is able to be opened. The door is one that can be opened remotely under electrical operation. The extended position of the locking bolt 2 is shown in Figs. 1 and 3, and the retracted position is shown in Figs. 2 and 4. A compression spring 12 mounted at the rear of the locking bolt 2 resiliently biases the bolt 2 towards its extended, locking, position, but the bolt can be moved from that position either by an electrical drive arrangement described below or by operation of a five lever lock 8 by a key, that operation causing rotary movement of a cam of the lock 8 which engages the bolt 2 to retract the bolt in a manner known per se. In the drawings the lock 8 is shown schematically in dotted outline.

[0030] The electrical drive is provided by a post 14 on the drive wheel 3 engaging a "V" shaped recess 15 in an upstanding part 16 of the coupling member 6. The coupling member 6 is pivotally mounted at one end (the right hand end as seen in the drawings) for pivotal movement about a stump or pin 17 and the degree of movement allowed is controlled by engagement of a stump or pin 18 on the bolt 2 in an arcuate slot 19 in the coupling member 6. In the particular example of the invention shown in the drawing the coupling member 6 is able to pivot through an angle of about 15 degrees. In Fig. 1 the coupling member 6 is shown pivoted into its upper position whilst in Fig. 2 it is shown in its lower position. Gravity biases the coupling member 6 into its lower position but, when the bolt 2 is in its extended position, a spring biased plunger 20 presses against the upstanding part 16 of the coupling member 6 raising it into its upper position.

[0031] When, in use, the drive wheel 3 is driven by the motor 5 (following actuation of the solenoid 7) via the worm gear 4 it is always driven in an anti-clockwise (as seen in the drawings) direction. Starting from the position shown in Fig. 1, such rotation of the drive wheel 3 causes the post 14 to engage the "V" shaped recess 15, driving the bolt 2 to the right (as seen in the drawings) against the bias of the spring 12. As the bolt 2 moves to the right, the plunger 20 ceases to engage it, but the engagement of the post 14 continues to maintain the coupling member in its upper position and the bolt 2 is driven to its retracted, released, position. As the bolt 2 reaches that position, the post 14 moves upwards out of engagement with the coupling member 2 which then pivots down under gravity to the position shown in Fig. 2. In this position of the coupling member 2 it is clear of the rotary path of the post 14 and therefore, even if there is a power failure, wherever the post 14 may be positioned around its path, it does not interfere with the mechanical operation via the key of the lock 8 to move the bolt 2 as desired.

[0032] Referring now especially to Figs. 3 and 4, the lock assembly is also provided with a retaining device 11 which interacts with the auxiliary bolt 10 and the locking bolt 2 in order to retain the locking bolt 2 in a retracted position, against the bias of the spring 20, when, with the door shut, the locking bolt 2 is retracted after the auxiliary bolt 10 has been retracted. The retaining device 11 generally comprises a housing 24, a plunger part 25 which is rigidly coupled to the auxiliary bolt 10 for movement therewith and is slidable in the housing 24, a ball guide part 26 slidably mounted in the housing 24 on a spindle 33 extending from the plunger part 25 and drivingly coupled to the plunger part 25 via a compression spring 27 and an end flange 32 on the spindle 33, and a locking ball 28 which is movable radially (in a direction upwardly and downwardly as seen in the drawings) between a lower position in which it is accommodated within a groove 29 in the ball guide part 26 and does not project out of the housing 24, and an upper position in which it rests on a portion 30 of the ball guide part 26, projects out of the housing 24 and engages in a recess 31 in the locking bolt 2. Fig. 3 shows the ball 28 in its lower position and Fig. 4 shows the ball 28 in its upper position. As will now be understood, when the ball 28 is in its lower position, the locking bolt 2 is free to move between its extended and retracted positions but when the ball 28 is in its upper position, the locking bolt 2 is fixed in its retracted position.

[0033] When the door is open the auxiliary bolt 10 is in the extended position shown in Fig. 3, but when the door is closed it is held in the retracted position shown in Fig. 4. While the bolt 2 remains in its extended position, the ball 28 is unable to move upwards even with the auxiliary bolt 10 retracted and the guide part 26 therefore remains static causing the spring 27 to compress. When the bolt 2 is retracted with the door closed and the auxiliary bolt therefore still held in its retracted position, the ball 28 is then able to move upwardly into the recess 31 in the bolt 2, allowing the guide part 26 to move to the right to the position shown in Fig. 4, thereby ensuring that the ball 28 remains in its upper position. The bolt 2 is then unable to move out of its retracted position and there is therefore no risk of the bolt 2 returning to its extended position before the door has been opened. This feature of holding the bolt 2 in its retracted position is of special value in the case of an electrically operated door where there is a time interval between retracting the bolt 2 and opening the door.

[0034] When the door is open, as shown in Fig. 3, the auxiliary bolt 10 is biased by a compression spring 35 into its extended position, the ball guide part 26 is moved to the left (as shown in Fig. 3) by engagement of the end flange 32 of the spindle with the ball guide part 26 and the ball 28 is able to drop into the groove 29 in the ball guide part 26 allowing the bolt 2 to move.

[0035] As will be understood, the retaining device 11 is an additional feature added to the auxiliary bolt arrangement which interacts with the main bolt in various ways that are known per se and that involve the use of a swinging arm 37 pivotally mounted on a shaft 36 and will not be described further herein.

Claims

1. A lock assembly comprising
a casing,
a locking bolt movable between an extended, locking, position in which the locking bolt projects out of the casing and a retracted, released, position,
a drive including a drive member for driving the locking bolt into the retracted, released, position, and
a coupling member adjustable between a first state in which the coupling member is effective to transmit the drive from the drive member to the locking bolt to move the locking bolt from the extended, locking, position into the retracted, released, position, and a second state in which the coupling member is not effective to transmit drive from the drive member to the locking bolt, the coupling member being biased into the second state but being arranged to adopt the first state when the locking bolt is in the extended, locking, position and to remain in the second state as the drive member drives the locking bolt into the retracted, released, position.

2. An assembly according to claim 1, in which the drive is an electrically operated drive.

3. An assembly according to any preceding claim, in which the drive is a rotary drive and the drive member comprises a post projecting from a drive wheel.

4. An assembly according to any preceding claim, in which the coupling member is pivotally mounted on the locking bolt and pivotal movement of the coupling member moves it between the first and second states.

5. An assembly according to any preceding claim, in which the coupling member is biased into the second state by gravity.

6. An assembly according to any preceding claim, in which, when the locking bolt is in the extended, locking, position a stop member engages the coupling member to hold it against its bias in the first state.

7. An assembly according to claim 6, in which the stop member is mounted on the casing of the assembly and is resiliently biased into contact with the coupling member when the locking bolt is in the extended, locking, position.

8. An assembly according to any preceding claim, further including
an auxiliary bolt which is mounted in the casing for movement between an extended position in which the auxiliary bolt projects out of the casing and a retracted position, and
a bolt retaining device for retaining the locking bolt in its retracted, released, position, when the auxiliary bolt is in its retracted position.

9. An assembly according to claim 8, in which the bolt retaining device includes a retaining member for engaging the locking bolt in its retracted, released, position, the retaining member being movable between a first, retaining, position for retaining the locking bolt in its retracted, released, position and a second position for allowing the locking bolt to move out of its retracted, released, position.

10. An assembly according to claim 9, in which, when the auxiliary bolt is in its retracted position, the retaining member is resiliently biased into its first, retaining, position.

11. An assembly according to claim 9 or claim 10, in which, when the auxiliary bolt is in its retracted position, the retaining member is in its first retaining position, and the locking bolt is in its retracted, released, position, the locking bolt is unable to move out of its retracted, released, position until the auxiliary bolt moves towards its extended position.

12. An assembly according to any of claims 9 to 11, in which the bolt retaining device includes a first part mounted for movement with the auxiliary bolt and a second part whose movement causes the movement of the retaining member, the first and second parts being coupled by a resilient coupling, the first and second parts being arranged for linear movement.

13. A lock assembly comprising
a casing,
a locking bolt movable between an extended, locking, position in which the locking bolt projects out of the casing and a retracted, released, position,
an auxiliary bolt which is mounted in the casing for movement between an extended position in which the auxiliary bolt projects out of the casing and a retracted position, and
a bolt retaining device for retaining the locking bolt in its retracted, released, position, when the auxiliary bolt is in its retracted position.

14. An assembly according to claim 13, in which the assembly includes any of the features defined in claims 9 to 13.

15. A door fitted with a lock assembly according to any preceding claim.

Drawing