Patent Publication Number: US-7591157-B2

Title: Security lock arrangement

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Provisional Patent Application No. 2003905640 filed on 16 Oct. 2003, the contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     This invention relates to a security lock. More particularly, the invention relates to a security lock arrangement for securely locking a wing member in a closed position relative to a surround. 
     BACKGROUND TO THE INVENTION 
     The use of security doors is becoming increasingly important, both from a safety aspect and for inhibiting unauthorised access to premises. 
     Latch-type locks make use of a latch bolt that is received in a frame surrounding a wing member hingedly arranged in the frame. The wing member is, conventionally, a door or window. Typically, the latch bolt is received through a striker plate mounted on the frame and can be retracted to an unlocked position to facilitate opening of the wing member. 
     Such latch members normally have a slanted face. If the wing member opens inwardly, the slanted face faces outwardly and this can render it relatively easy for a determined entrant to gain entry into the premises by forcing retraction of the latch bolt. 
     In addition, the use of only a single latch bolt further compromises the security of such a locking arrangement. 
     The Applicant has previously proposed the use of a plurality of latch bolts to improve the security of a security locking arrangement. Either two such latch bolts or four such latch bolts, arranged in a cruciform fashion, are mounted on the wing member. Preferably, the latch bolts are arranged on an outer surface of an operatively inner side of the wing member and this provides the advantage that the security locking arrangement can be retrofitted to an existing door. These latch bolts are also flat ended, i.e. they do not have a slanted faces. 
     The use of electronic access is also becoming increasingly prevalent. In addition, the Applicant has determined that the torque required to turn a key in a key lock of a security lock, arranged on an opposite side of the wing member to a handle, can be high resulting in the possibility of the key snapping with a blade of the key remaining in a barrel of the lock. 
     The Applicant has also determined that, particularly, with the use of electronic access facilities, an enhanced latching mechanism is required for extending the latch bolts to their locked positions upon closure of the wing member. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, there is provided a security lock arrangement which includes: 
     a carrier to be mounted on a wing member; 
     at least one latch bolt displaceably arranged relative to the carrier between a retracted, unlocked position and an extended, locked position; 
     an urging means acting on the at least one latch bolt for urging the latch bolt to its extended, locked position; 
     a drive means mounted on the carrier for driving the at least one latch bolt at least into its retracted position against the action of the urging means; and 
     a displacement mechanism interposed between the drive means and the at least one latch bolt, the displacement mechanism comprising a cam member rotatably driven by the drive means, the cam member acting on a follower of the at least one latch bolt, the cam member having a maximum throw when the at least one latch bolt is proximate its retracted position. 
     According to a second aspect of the invention, there is provided a security lock arrangement which includes: 
     a carrier to be mounted on a wing member; 
     at least one latch bolt displaceably arranged relative to the carrier between a retracted, unlocked position and an extended, locked position; 
     an urging means acting on the at least one latch bolt for urging the latch bolt to its extended, locked position; 
     a displacement mechanism for displacing the at least one latch bolt at least to its retracted, unlocked position against the action of the urging means; 
     a holding assembly for holding the at least one latch bolt in its retracted position; and 
     a non-contact, proximity detection unit for determining when the wing member is in its closed position relative to a surround of the wing member, the proximity detection unit, upon detecting that the wing member is closed, acting on the holding assembly to cause the holding assembly to disengage the at least one latch bolt so that the at least one latch bolt moves to its extended, locked position under the action of the urging means. 
     According to a third aspect of the invention, there is provided a security lock arrangement which includes: 
     a carrier to be mounted on a wing member; 
     at least one latch bolt displaceably arranged relative to the carrier between a retracted, unlocked position and an extended, locked position; 
     an urging means acting on the at least one latch bolt for urging the latch bolt to its extended, locked position; and 
     an operating mechanism which acts on the at least one latch bolt to withdraw the latch bolt from its locked position to its unlocked position, the operating mechanism comprising, in combination, a handle mountable on one side of the wing member and a key lock mechanism mountable on an opposed side of the wing member, the key lock mechanism including a barrel in register with a rotational axis of the handle, the barrel and the handle being connected by a link, the link including a lost motion component to allow the barrel and the handle to operate, at least partially, independently of each other. 
     In a preferred form of the invention, the security lock arrangement comprises at least two latch bolts extending in opposite directions. In a most preferred form of the invention, the security lock arrangement comprises two pairs of orthogonally arranged latch bolts. In respect of each pair, the latch bolts extend in opposite directions. As previously indicated, a free end of each latch bolt is flat-ended. 
     The latch bolts may be arranged in a cruciform-arrangement on the wing member, which may be a door, and, when in their locked positions, project beyond edges of the door approximately mid-way along the length of each edge of the door The handle of the operating mechanism may be arranged proximate a free edge of the door, i.e. an edge of the door opposite the edge of the door carrying the hinges, on an operatively inner side of the door. The key lock mechanism may be arranged on an operatively outer side of the door. 
     Each latch bolt may have a carrier associated with it, each carrier being in the form of a carrier plate mountable to an operatively inner surface of the wing member. For aesthetic reasons, the carrier plates may each be covered by a cover member. At least one carrier plate may be arranged in segments to facilitate adjustment of the length of the carrier plate to cater for wing members of different sizes. 
     Each latch bolt may be mounted on a control arm, an operatively inner end of the control arm being pivotally secured to a rotary element arranged substantially centrally on the carrier plate. The rotary element may carry the follower, the follower being eccentrically arranged on the rotary element so that, when the cam rotates, it drives the rotary element through a predetermined arc to cause the control arms to be drawn inwardly to retract the latch bolts to their unlocked position. 
     The cam may be arranged so that, when the latch bolts are in their retracted position, the follower is at a position of maximum throw of the cam. A recessed region may be arranged on a surface of the cam following the position of maximum throw so that, as the cam continues to rotate, the follower moves into register with such recessed region. Thus, in use, the drive means, which may be in the form of an electric motor-gearbox combination, may drive the cam to unlock the door by retracting the latch bolts. After a delay period, which may be set by a user, the cam rotates further in the same direction. However, the latch bolts are retained in their retracted position by means of the holding means. When the proximity detection unit detects that the door is closed, the holding means may disengage from its associated latch bolt. Because all the latch bolts are interconnected by the rotary member, when the latch bolt associated with the holding means is held in its retracted position by the holding means, all the latch bolts are held in their retracted position. Conversely, when the holding means disengages from its associated latch bolt and, provided the latch bolts are not being held in their retracted position by the drive means, all the latch bolts extend to their locked position. 
     Preferably, the proximity detecting unit is associated with the latch bolt closest to the handle but this need not be the case. The control arm for the latch bolt associated with the proximity detection unit may be connected to the latch bolt via a positive drive arrangement. The positive drive arrangement may be in the form of a rack and pinion arrangement. Thus, the control arm may terminate in a first rack displaceably arranged relative to the carrier, teeth of the rack meshing with teeth of a pinion. A second rack may be arranged on an opposed side of the pinion to which the latch bolt is connected. 
     The holding assembly may be in the form of a pawl which engages a receiving formation associated with the positive drive arrangement. The pawl may be pivotally mounted on the carrier and may be biased by a coil spring into engagement with the receiving formation. 
     The proximity detection unit may comprise a magnetic assembly having a first magnet mounted in a wing member frame and a second magnet displaceably arranged relative to the carrier proximate a free edge of the wing member. The second magnet may be operatively associated with the pawl to act on the pawl so that, when the second magnet is attracted by the first magnet, when the wing member is in its closed position, the pawl is urged out of engagement with the receiving formation to release the latch bolts to enable the latch bolts to extend to be received in their respective striker plates under the action of the urging means. 
     The magnets are, preferably, high strength magnets and, more particularly, may be rare earth magnets. 
     The link connecting the handle and the barrel may comprise a pair of co-axially aligned spindles interconnected by an axle or pin. A first of the spindles may be connected to the handle with the second of the spindles being associated with the barrel of the lock, the pin being arranged at facing, inner ends of the spindles. 
     The first spindle may have a drive member on its inner end with the second spindle having a driven member on its second end on which the drive member acts. The drive member may have a drive bar extending parallel to a direction of rotation of the spindles. The drive bar may engage a bearing formation of the driven member so that, when the handle is rotated to unlock the security lock arrangement, both spindles rotate. Conversely, when the second spindle is rotated via a key inserted into the barrel of the lock, only the second spindle rotates. 
     The lost motion link may include a connecting formation at an outer end of the second spindle via which the barrel of the key lock is connected to the second spindle. The key lock may include a blade projecting from the barrel which is received in the connecting formation. 
     The connecting formation may comprise a pair of opposed, spaced slot-defining members at an outer end of the second spindle, the slot-defining members having shaped, or bevelled, surfaces so that, when the second spindle is rotated under the effect of the handle, the slot-defining members can rotate relative to the blade of the key lock without impinging on the blade but, when the key lock is used to unlock the security lock arrangement, the blade bears against the slot-defining members to cause rotation of the second spindle only. 
     The invention extends also to a component for a security lock arrangement, the component comprising a link for interconnecting a handle and a key lock of the security lock arrangement, the link including a lost motion component to allow the barrel and the handle to operate, at least partially, independently of each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the invention is now described by way of example with reference to the accompanying diagrammatic drawing in which: 
         FIG. 1  shows a three dimensional view of a security lock arrangement, in accordance with an embodiment of the invention, mounted on a door; 
         FIG. 2  shows a schematic, plan view of part of the security lock arrangement in its locked position; 
         FIG. 3  shows a plan view of the security lock arrangement in its unlocked position; 
         FIG. 4  shows a schematic, plan view of a further part of the security lock arrangement; 
         FIG. 5  shows a plan view of the part of  FIG. 4 ; 
         FIG. 6  shows a schematic plan view of yet a further part of the security lock arrangement; 
         FIG. 7  shows a schematic plan view of still a further part of the security lock arrangement; 
         FIG. 8  shows a side view of a lost motion link of the part of  FIG. 7 ; and 
         FIG. 9  shows an end view of the link. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT 
     In the drawings, reference numeral  10  generally designates a security lock arrangement, in accordance with an embodiment of the invention. For the sake of brevity, the security lock arrangement will be referred to as a “lock” or “security lock” in this description. 
     The security lock  10  is mounted on an operatively inner side  12  of a door  14 . The door  14  has a hinge edge  16 , a free edge  18 , a top edge  20  and a bottom edge  22 . The door is hinged to a frame  24  mounted in a reveal (not shown) of premises. A door closer  26  retains the door  14  in its closed position relative to the frame  24 . 
     The security lock  10  has four latch bolts  28 ,  30 ,  32  and  34  for locking the door  14  in its closed position relative to the frame  24 . Each latch bolt  28 ,  30 ,  32  and  34  is received in an opening in a striker plate  36  mounted on the frame  24 . 
     Further, each latch bolt  28 - 34  is mounted to a control arm  38  ( FIGS. 2 and 3 ). Each control arm  38  overlies a carrier in the form of a carrier plate  40 . It is to be noted that the carrier plate  40  associated with the two vertical control arms  38  is omitted from  FIGS. 2 and 3  of the drawings for the sake of clarity. 
     Each carrier plate  40  has a pair of slots  42  to permit sliding displacement of a segment  44  of each carrier plate  40  to cater for different heights and widths of door  14 . 
     There are various ways of opening the door  14  relative to the frame  24  by unlocking the security lock  10 . Thus, the security lock  10  includes a handle  46  ( FIG. 1 ). A key lock  48  ( FIG. 7 ), which will be described in greater detail below, is arranged on an opposed side of the door  14  for facilitating opening the door via a key  50 . 
     In addition, electronic access, for example, via a keypad (not shown) is also possible. For this purpose, the security lock  10  includes a drive means in the form of an electric motor-gearbox combination  52  ( FIGS. 4 and 5 ) for causing retraction of the latch bolts  28 - 34 . 
     The motor-gearbox combination  52  drives the latch bolts  28 - 34  into their retracted, unlocked position in which they are free of the striker plates  36  allowing the door  14  to be opened relative to the frame  24 . The motor of the combination  52  is controlled by an adjustable time delay mechanism (not shown). This time delay mechanism can be set by a user and typically has a time delay period of between about 3 seconds and 30 seconds. If the door  14  is not opened in that time, the motor-gearbox combination  52  allows the latch bolts  28 - 34  to return to their extended, locked positions. 
     More particularly, the motor-gearbox combination  52  drives a rotary element  54 , to which inner ends of the control arms  38  are pivotally connected, through a predetermined arc of movement which is sufficient to retract the latch bolts  28 - 34 . 
     The rotary element  54  comprises two rotary members  56  and  58  overlying an urging means in the form of a spirally wound spring  60  ( FIG. 2 ), of the security lock  10 . For the sake of clarity, the inner rotary element  58  is shown separately in  FIGS. 2 and 3  of the drawings. In addition, it will be noted that only the control arm  38  associated with the latch bolt  34  is connected to the inner rotary member  58 . The other control arms  38  are connected to the outer rotary member  56 . The “inner” rotary member  58  is the one close to the carrier plate  40 . 
     As shown in greater detail in  FIG. 4  of the drawings, the security lock  10  includes a displacement mechanism  62  interposed between the motor-gearbox combination  52  and the rotary element  54 . 
     The displacement mechanism  62  comprises a cam  64  mounted on an output shaft  66  of the motor-gearbox combination  52 . The cam  64  bears against a follower  68  which is eccentrically mounted on the rotary member  56  of the rotary element  54 . When the motor of the combination  52  is operated, the cam  64  rotates and bears against the follower  68  causing rotation of the rotary element  54  from the position shown in  FIG. 2  of the drawings to the position shown in  FIG. 3  of the drawings. When the latch bolts  28 - 34  are in their fully retracted position as shown in  FIG. 3  of the drawings, the cam  64  is at its maximum throw. It is also to be noted that the latch bolts  28 - 34  are retracted against the action of the spring  60  and the spring  60  is driven to the position shown in  FIG. 3  of the drawings. 
     After the time delay period as set by the user has timed out, the motor continues rotating in the same direction to cause the cam  64  to move beyond its point of maximum throw relative to the follower  68 . However, the latch bolts  34 , if the door  14  is open relative to the frame  24 , are retained in their retracted, unlocked positions by a holding means  70 , as will be described in greater detail below. The cam  64  has a recessed region  72  ( FIGS. 2 and 3 ) which lies substantially in register with the follower  68  after the cam  64  has moved beyond its position of maximum throw. 
     With this arrangement, it is ensured that, should the door  14  be in its closed position relative to the frame  24  and the time delay period times out, the latch bolts  28 - 34  move to their locked, extended positions. 
     The control arm  38  associated with the latch bolt  30  drives that latch bolt  30  via a positive displacement mechanism  74 . The positive displacement mechanism  74  is a rack and pinion arrangement. One end of the control arm  38  is connected to a rack  76  which is displaceable parallel to the direction of movement of the latch bolt  30 . Teeth of the rack  76  mesh with a pinion  78  rotatably mounted on the carrier plate  40  associated with the latch bolt  30 . The latch bolt  30 , in turn, is driven by the pinion  78  via a second rack  80  mounted on an opposite side of the pinion  78  to the rack  76 . 
     A disk  82  (shown most clearly in  FIG. 6  of the drawings) underlies the pinion  78  and is rotatably fast with the pinion  78 . 
     The holding means  70  comprises a pawl  84  which, when the latch bolt  30  is in its retracted position, is received in a recessed formation  86 . The pawl  84  is mounted at the end of an arm  88  which is pivotally mounted via a substantially centrally located pivot pin  90  to the carrier plate  40 . The arm  88  is biased by a coil spring  92  into the position in which the pawl  84  engages the recess  86 . 
     Hence, when the latch bolts  28 - 34  are withdrawn into their retracted, unlocked positions and the door  14  is in an open position relative to its frame  24 , the disk  82  rotates from the position shown in  FIG. 2  of the drawings to the position shown in  FIG. 3  of the drawings. When the recess  86  comes into alignment with the pawl  84 , the arm  88  rotates about the pin  90  under the action of the coil spring  92  driving the pawl  84  into the recess  86  and holding the disk  82  in that position. With this arrangement, the latch bolts  28 - 34  are retained in their retracted, unlocked positions. The latch bolts  28 - 34  will remain in this position for so long as the door  14  is held open relative to the frame  24 . 
     The security door lock  10  includes a non-contact proximity detection unit  94  ( FIGS. 2 ,  3  and  6 ) which senses when the door  14  is in its closed position relative to the frame  24 . The proximity detection unit  94  is associated with the latch bolt  30  and includes a first magnet  96  mounted in the striker plate  36  of the latch bolt  30  and a second magnet  98  slideable piston-fashion in a cylinder  100  mounted at the end of the carrier plate  40  associated with the latch bolt  30 . 
     The magnets  96  and  98  are strong magnets such as rare earth magnets. 
     The magnet  98  is connected to an end of the arm  88  opposite the end having the pawl  84  via a connector rod  102 . When the pawl  84  engages the recess  86  of the disk  82  and holds the latch bolts  28 - 34  in their retracted position, the magnet  98  is, similarly, held in a retracted position relative to the cylinder  100 . When the door  14  closes, and assuming the time delay of the motor-gearbox combination  52  has timed out so that the cam  64  no longer engages the follower  68 , the magnet  96  attracts the magnet  98  from the position shown in  FIG. 3  of the drawings to the position shown in  FIG. 2  of the drawings. This causes the arm  88  to pivot relative to the pivot pin  90  against the action of the coil spring  92  pulling the pawl  84  out of engagement with the recess  86 . When this occurs, the spiral spring  60  drives the rotary element  54  to cause the latch bolts  28 - 34  to be extended into their locked configuration in which they engage their associated striker plates  36 . It will be appreciated that, if the time delay of the motor has timed out, the cam  64  is no longer in abutment with the follower  68  so that there is no longer any impediment to the spring  60  driving the latch bolts  28 - 34  to their locked positions. 
     The handle  46  of the security lock  10  is connected to the key lock  48  by means of a lost motion link  104 . The link  104  is shown in greater detail in  FIG. 8  of the drawings. The link  104  comprises a first spindle  106  to which the handle  46  is connected. A second spindle  108  is co-axially aligned with the spindle  106 . The second spindle  108  is associated with the key lock  48 . 
     The spindles  106  and  108  are connected together via an axle or pin  110  protruding into bores at facing, inner ends of the spindles  106 ,  108 . 
     The first spindle  106  has a drive member  112  at its inner end. The drive member  112  had a drive bar or finger  114  which extends in a direction parallel to a longitudinal axis of the spindle  106 . The spindle  108  has a driven member  116  at its inner end and has a bearing formation  118  projecting radially outwardly from the driven member  116 . The bearing formation  118  is engaged by the drive bar  114  of the spindle  106 . Hence, when the handle  46  of the security lock  10  is rotated in the direction of arrow  120  ( FIG. 9 ), both spindles  106  and  108  rotate. However, when the key  50  is used to unlock the security lock, the key  50  is also rotated in the direction of the arrow  120 . It is to be noted that the bearing formation  118  moves out of engagement with the drive bar  114  so that only the spindle  108  rotates and less torque is required on the key  50  to unlock the security lock  10 . Thus, the key lock  48  is, effectively, decoupled from the handle  46  via the lost motion link  104 . 
     Also, for this purpose, an operatively outer end of the spindle  108  is bifurcated and is formed by a pair of opposed, spaced, staggered slot-defining bosses  122 . A shown more clearly in  FIG. 7  of the drawings, a barrel  124  of the key lock  48  engages the spindle  108  via a blade  126 . The position of the blade  126  is shown in dotted lines in  FIG. 9  of the drawings. 
     Each slot-defining boss  122  has a bevelled end to define a pair of lands  128  and  130  which have an obtuse included angle. At rest, the blade  126  bears against the lands  128 . When the key  50  is used to unlock the security lock, the barrel  124  of the key lock  48  is rotated in the direction of the arrow  120  so that the blade  126  bears against the lands  128  causing the spindle  108  to rotate in the direction of the arrow  120 . Conversely, bearing in mind that the barrel  124  is locked against rotation if the key  50  is removed, when the handle  46  is used to rotate the link  104 , the spindle  108  rotates in the direction of the arrow  120  so that the blade  126  moves out of engagement with the lands  128  towards the lands  130  of the opposite bosses  122  allowing the spindle  108  to rotate freely relative to the blade  126  without being impeded by the locked barrel  124  of the key lock  48 . 
     It is to be noted that the mechanism of the door lock  10  is covered by cover plates  132 . In addition, the motor-gearbox combination  52  is covered by a cover plate  134  ( FIG. 1 ). 
     It is, accordingly, an advantage of the invention that a security lock  10  is provided which allows the use of electronic access techniques without compromising the security of the lock  10 . In addition, a non-contact proximity detection unit is provided for detecting when the door  14  is closed relative to the frame  24 . The Applicant believes that this provides an improved level of security as it inhibits jamming of the latch bolts  28 - 34  into a retracted position. Still further, the use of the lost motion link  104  reduces the torque which needs to be imparted to the key  50  of a key lock  48  thereby reducing the risk of the key shearing or snapping in the barrel  124  of the key lock  48 . 
     It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.