Patent Publication Number: US-2015084348-A1

Title: Door locking installation and locking mechanism

Description:
TECHNICAL FIELD  
     The present invention relates to door locking installations and locking mechanisms and particularly to locking installations and mechanisms systems suitable for use in locking a pair of bi-directional swing doors at the lower edge of the doors. 
     BACKGROUND TO THE INVENTION 
     In some door arrangements, such as in the case of bi-directional swing doors, it is not possible to fit mechanical stops to align the door in position for locking the door. 
     Therefore, it is usually only possible to lock the doors from a position at the top of the door frame. However, this situation is undesirable as persons pushing at the lower region of the door can cause a significant amount of deflection to the door, resulting in either damage to the door, or failure of the top mounted locking arrangement resulting in unauthorised access through the door. 
     SUMMARY OF THE INVENTION 
     In a first aspect the present invention provides a door locking installation comprising: a locking mechanism mounted below floor level in association with a door and including a locking element which is moveable between a retracted position and an extended position; an electrically powered actuator which is arranged to drive the locking mechanism by way of a mechanical linkage; the mechanical linkage separates the actuator from the locking mechanism; and wherein the actuator is mounted above floor level. 
     The mechanical linkage may include a flexible drive cable mounted in a flexible sheath. 
     The flexible drive cable may be arranged to rotate within the flexible sheath. 
     The door locking installation may further include a power storage device to provide power to the actuator in the event that mains power is lost. 
     The door locking installation may be arranged to move the lock to an unlocked condition in the event that mains power is lost. 
     In a second aspect the present invention provides a locking mechanism which is arranged for mounting below floor level in association with a door including: a housing; a locking element is mounted in the housing and is associated with a threaded element; rotation of the threaded element causes movement of the locking element between a retracted position and an extended position. 
     The locking element may include two projecting fingers. 
     When in the extended position, the locking element may be arranged to rotate between a first position and a second position. 
     The housing may include guide means which controls rotational movement of the locking element. 
     The guide means may include grooves provided on the inside surface of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view showing an embodiment of a door locking arrangement according to one aspect of the invention including a locking mechanism according to another aspect of the invention which is shown in exploded view; 
         FIG. 2  is a perspective view of the housing of the locking mechanism of  FIG. 1 ; 
         FIG. 3  is an enlarged exploded view of selected components of the locking mechanism of  FIG. 1 ; 
         FIG. 4  is a cut-away perspective view of the locking mechanism of  FIG. 1  shown in the unlocked condition in association with a door; 
         FIG. 5  shows the locking mechanism of  FIG. 4  with locking element in the extended position; 
         FIG. 6  shows the locking mechanism of  FIG. 4  in the locked condition; and  FIG. 7  is a top view the locking mechanism in the locked condition of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a door locking installation  10  is shown including a door locking mechanism  20  shown in exploded view, an electrically powered actuator in the form of electric motor and gearbox combination  50 , and a mechanical linkage in the form of flexible drive cable  70 . Locking mechanism  20  is arranged to be mounted in the floor below the bottom edge of a door (not shown). A hole is formed in the floor using a core drill of a suitable diameter to seat mounting ring  22  at the top edge of the hole and of sufficient depth to accommodate the mechanism  20 . When installed in the floor, the top surfaces of outer cover plate  32  and inner cover plate  30  lie generally flush with the surrounding floor surface. 
     Flexible drive cable  70  is mounted in a flexible sheath and is arranged to rotate to transfer rotational motion of the output of motor and gearbox combination  50  to the input shaft  21   a  of mechanism  20 . Drive cable  70  operates on the same principle to the type of cable often used as a speedometer cable in automotive applications. 
     Electric motor  50  is operated under the control of controller  60  which itself is connected to a building control system to allow for remote and automatic operation of the locking installation  10 . By causing drive cable  70  to rotate in either a clockwise, or anticlockwise direction, the locking mechanism is caused to move between a locked and an unlocked condition as will be later described. 
     Importantly, controller  60  and motor and gearbox combination  50  are mounted to a wall to one side of the door and are situated above floor level. Therefore, the electronic components inside controller  60  and motor  50  are not at risk of damage from moisture or liquid that may be present on the floor due to, for instance, rainfall or floor-cleaning operations. 
     The components and operation of locking mechanism  20  will now be described. 
     Referring to  FIG. 1 , locking mechanism  20  includes a housing  24  to which is mounted support plate  28  by way of rotatable roller bearing  29  to allow support plate  28  to rotate with respect to housing  24 . A threaded rod  27  is located at its upper end in support plate  28  in smaller roller bearing  27   a  and is thus rotatable with respect to support plate  28 . 
     A locking element is comprised of a base plate  26  to which are mounted two projecting fingers  34 . Base plate  26  is threadedly engaged with threaded rod  27 . Therefore, rotation of threaded rod  27  results in either upward or downward movement of base plate  26  with respect to threaded rod  27  depending upon the direction of rotation of threaded rod  27 . 
     Fingers  34  are a sliding fit in bushes  28   a  of support plate  28  and further sit inside apertures  31  provided in inner cover plate  30 . Inner cover plate  30  is affixed to support plate  28  with by way of a series of six equally spaced screws. 
     Base plate  26  includes two lugs  38  which cooperate with guide means in the form of two diametrically opposed grooves provided on the inner surface of housing  24 . Referring to  FIG. 2 , one of grooves  36  is visible inside housing  24  and includes a vertical portion  37  and a horizontal portion  37   a.  Grooves control movement of the base plate  27  with respect to housing  24 . 
     Referring to  FIGS. 4 ,  5  and  6 , operation of locking mechanism will be described. 
     Referring to  FIG. 4 , mechanism  20  is shown in its unlocked condition. A portion of a door  80  is shown in its usual closed position where it generally overlies locking mechanism  20 . Base plate  26  is positioned at the lower end of threaded rod  27  and thus fingers  34  are in their retracted position. The top surfaces of fingers  34  lie flush with inner cover plate  30 . 
     Lock is moved to the locked condition by rotation of input shaft  21  a in an anti-clockwise direction. Rotational movement of input shaft  21  a is translated to rotation of threaded rod  27  by way of bevel gears  21 ,  23 . As threaded rod  27  rotates, it causes upward movement of base plate  26  due to the threaded engagement of the base plate  26  with threaded rod  27 . As base plate  26  rises, it is constrained in fixed rotational orientation with respect to housing  24  by virtue of lugs  38  being located in the horizontal portion  37  of grooves  36 . As base plate  26  rises, lugs  38  move upwards along groove portions  37  and fingers  34  extend out of the apertures  31  in inner cover plate  30 . 
     Referring to  FIG. 5 , fingers  34  are in their fully extended position and lugs  38  have now reached the top of horizontal groove portions  37  and are now free to travel along horizontal groove portions  37   a.  Furthermore, base plate  26  has reached the limit of upper travel on threaded rod  27  as it has come into contact with support plate  28 . Therefore, continued rotation of threaded rod causes rotation of all of support plate  28 , base plate  26 , fingers  34  and inner cover plate  30  in unison. This brings fingers  34  into contact with opposite sides of door  80  which causes door  80  to become aligned with the centre of rotation of mechanism  20  and to be restrained from movement by way of fingers  34  being in contact with both sides of door  80 . 
     When the mechanism has reached the rotational position shown in  FIG. 6 , it can move no further. This is detected by controller  60  by a sudden sharp rise in the current drawn by motor  50 . When controller  60  detects this condition power to motor  50  is cut. Locking mechanism  20  is now in its locked condition. Door  80  is held locked in place by fingers  34  (see  FIG. 7 ). 
     A micro-switch may be operated by post  41  (shown in  FIG. 3 ) to indicate that base plate  26  has reached the upper extent of its travel. Therefore, if controller  60  detects a rise in current and micro-switch has not been operated then this indicates that lock  20  has not successfully moved to the locked condition. Controller can then back up the motor and attempt to repeat the locking operation, and may indicate an error condition after a number of failed attempts. 
     Movement from the locked condition back to the unlocked condition shown in  FIG. 4  is achieved by rotation of input shaft  21  a in the opposite direction. Initially, rotation of threaded rod causes rotation of the assembly of support plate  28 , base plate  26 , fingers  34  and inner cover plate  30  with respect to housing  24  back to the position shown in  FIG. 5  as lugs  38  move along groove portions  37 . Thereafter, lugs  38  prevent continued rotation, and base plate  26  moves back down threaded rod  27  until the position shown in  FIG. 4  is reached. When base plate  26  can move no further, this causes a sharp rise in the current drawn by motor  50  signalling to controller that the mechanism has reached the unlocked condition. Power to motor  50  is then cut and mechanism remains in the condition shown in  FIG. 4 . With fingers  34  again retracted, door  80  can be freely opened. 
     A microswitch may be employed to detect that the lugs  38  have rotated to align with vertical groove portions  37  before the sharp rise in motor current is detected to allow controller  60  to determine whether the mechanism has properly moved to the unlocked condition. In the event that the motor current rises before the lugs  38  have aligned with groove portions  37  the controller backs up the motor and tries a number of times to unlock the lock. Repeated failure will cause indication of an error condition. 
     The controller  60  includes a power storage device such as a battery or super-capacitor to enable fail safe operation. When operating in fail safe mode, in the event that power is cut to controller and the locking mechanism is in the locked condition, the controller uses power stored in the power storage device to move the locking mechanism to the unlocked condition. 
     It can be seen that embodiments of the invention have at least one of the following advantages:
         The locking mechanism mounted below floor level does not include any electrical driving parts such as an electric motor. Therefore, these parts are not susceptible to damage by way of ingress of water or other liquids which may be present on the floor.   The locking fingers of the mechanism are positively driven from the retracted position to the extended position and from the extended position back to the retracted position to provide reliable operation of the lock.       

     Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated. 
     Finally, it is to be appreciated that various alterations or additions may be made to the parts previously described without departing from the spirit or ambit of the present invention.