Abstract:
The present invention relates to a lock cylinder assembly ( 10 ) comprising a cylinder housing ( 12 ); a cylinder ( 14 ); a first electromagnetic coil ( 48 ); a first locking member ( 52 ); and a key. The cylinder ( 14 ) is rotatable in the cylinder housing ( 12 ) and the first locking member ( 52 ) is urged by a first magnetic field towards a locked position in which rotation of the cylinder ( 14 ) is prevented. In use, when the first electromagnetic coil ( 48 ) is energised upon the use of the key, a second magnetic field created thereby causes the at least one locking member ( 52 ) to move out of the locked position so as to allow said cylinder ( 14 ) to be rotated in the cylinder housing ( 12 ).

Description:
FIELD OF THE INVENTION 
   The invention relates to an electronic lock cylinder assembly. 
   BACKGROUND OF THE INVENTION 
   Electronic locks have a number of advantages over normal mechanical locks. They may be encrypted so that only a key carrying the correct code will operate the lock, and they may also contain normal mechanical tumblers. They may contain a microprocessor so that, for example, a record can be kept of who has operated the lock in a certain time period, or so that they are only operable at certain times. They may also have the advantage that, if a key is lost the lock may be reprogrammed to prevent the risk of a security breach, or to avoid the expense of replacement. 
   Locks utilising some type of electronic element are known. 
   U.S. Pat. No. 5,542,274 discloses a lock having a key-operated, rotatable cylinder. A latching element is located in the region of the boundary surface between the cylinder housing and the cylinder and is resiliently urged by springs into a groove in the cylinder. An electrically actuable blocking element is moveable between a release position in which the latching element can be moved out of the recess when the cylinder is rotated, and a blocking position. The cylinder cannot be turned by means of the key when the blocking element is in its blocking position because the blocking element prevents the latching element from being moved out of the groove in the cylinder. 
   U.S. Pat. No. 5,552,777 discloses a mechanical lock and key including an electronic access control feature for preventing opening of the lock, even with the correct mechanical key unless prescribed conditions are met. A cylinder rotatable in a cylinder housing is fitted with an “ID chip” and a switch connected to a solenoid capable of withdrawing a blocking pin when energised. The blocking pin is resiliently urged by a spring into a bore in the cylinder housing when the cylinder is in the locked position. When a key, containing a battery, microprocessor and database, is inserted into the lock an electrical connection is made to the ID chip, if the serial number of the ID chip matches one of the numbers held in the database, the key is authorised to open the lock. The switch is activated and the solenoid energised withdrawing the blocking pin against the action of the spring enabling mechanical opening of the lock. 
   WO 01/55539 discloses an electronic locking system having a cylinder housing in which a cylinder is rotatable, and having a lock member moveable between a locked position and an open position under the influence of a solenoid. In the locked position, the lock member prevents a spring loaded locking pin in the cylinder from being moved out of engagement with a cavity in the cylinder housing and so interferes with the rotary movement of the cylinder. The solenoid is energised when a key containing a power source and generating the correct signal is inserted into the lock, so moving the locking member into its open position and allowing the cylinder to be rotated. 
   All of the above locks suffer from the disadvantages that they are relatively complex and cumbersome and that they require mechanical springs to return the locking element to its locked position once the current has been removed. This leads to an increase in the space required within the lock for the locking members, and can also lead to a reduced life span of the lock caused by mechanical failure of the springs. 
   The lock cylinder assembly of the present invention seeks to obviate or mitigate the above disadvantages by providing a locking member that can be moved both into and out of its locked position without the need for any mechanical springs or other mechanical biasing means. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the present invention, there is provided a lock cylinder assembly comprising:
     i. a cylinder housing;   ii. a cylinder rotatable in said cylinder housing;   iii. at least one electromagnetic coil;   iv. at least one locking member which is urged by a first magnetic field towards a locked position in which rotation of the cylinder is prevented; and   v. a key;
 
wherein, in use, when said at least one electromagnetic coil is energised upon the use of the key, a second magnetic field created thereby causes said at least one locking member to move out of said locked position so as to allow said cylinder to be rotated in said cylinder housing.
   

   Preferably, said at least one electromagnetic coil is located entirely within said cylinder. 
   Preferably, said at least one locking member is moveable into and out of said locked position in a direction parallel to the axis of rotation of said cylinder. However, it is within the scope of the present invention for the said at least one locking member to be moveable into and out of said locked position in a direction perpendicular to the axis of rotation of said cylinder, or at any angle to said axis of rotation of said cylinder between parallel and perpendicular. 
   Preferably, the or each locking member is or includes a permanent magnet providing said first magnetic field. 
   Preferably, the or each electromagnetic coil comprises a coil with a soft magnetic core. The arrangement is preferably such that, when said electromagnetic coil is de-energised, said first magnetic field causes the locking member to be attracted to said soft magnetic core and thereby biased toward said locked position, and when said electromagnetic coil is energised, said locking member is repelled from said soft magnetic core away from the locked position so as to allow said cylinder to rotate in said cylinder housing. 
   In a preferred embodiment of the lock cylinder according to the present invention, said lock cylinder possesses a pair of locking members. 
   Preferably, the locking members are arranged to be moved in opposite directions under the influence of the magnetic field applied by said at least one electromagnetic coil in use. 
   Preferably, said current to energise said electromagnetic coil is provided by an external source. More preferably said external source is provided in the key. 
   Further embodiments of the present invention are envisaged in which; said at least one locking member is positioned between said electromagnetic coil and a further magnetic coil, and the further electromagnetic coil, when energised provides said first magnetic field to urge said locking member towards its locked position. 
   A further embodiment in which said at least one electromagnetic coil has a hard magnetic core is also envisaged. In this embodiment, said at least one locking member is or includes a permanent magnet which is arranged with respect to the hard magnetic core such that, when the electromagnetic coil is de-energised, said locking member is attracted toward the core and into its locking position. When a current of sufficient magnitude is passed through said electromagnetic coil, the polarity of said hard magnetic core is reversed causing said at least one locking member to be moved away from its locking position. In an alternative embodiment of this, the, each or at least one of the locking members is arranged so that it is repelled by the hard magnetic core into its locking position when the coil is de-energised, and so that it is attracted towards the core and out of its locking position when the coil is energised. 
   A further embodiment of the present invention in which said at least one locking member is or includes a soft magnetic material, and in which said electromagnetic coil includes a soft magnetic core, is contemplated. In this embodiment, a permanent magnet having a magnetic field strength of less than the electromagnetic coil when energised, is provided for the or each locking member. This is positioned on the opposite side of the soft magnetic locking member to the electromagnetic coil. In use, when said electromagnetic coil is de-energised, said locking member is attracted to said permanent magnet and held in a locked position so that said cylinder cannot be turned in said cylinder housing. When the electromagnetic coil is energised, the locking member is urged away from its locked position. 
   According to a second aspect of the present invention, there is provided a lock having a lock cylinder assembly according to the first aspect of the present invention connected to a latching means, wherein said lock cylinder acts to prevent or allow said latching means to be operated dependant upon whether said at least one locking member of said lock cylinder is or is not in its locked position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the present invention will now be described in more detail by way of example only, with reference to the accompanying drawings, in which: 
       FIG. 1  is a longitudinal cross section of a lock cylinder assembly according to the present invention, and 
       FIG. 2  is an exploded view of the lock cylinder assembly of  FIG. 1 , 
       FIG. 3  is perspective view of one half of the cylinder housing of the lock cylinder assembly of  FIG. 1 , and 
       FIG. 4  is a perspective view of the cylinder of the lock cylinder assembly of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIG. 1 , in this embodiment the lock cylinder assembly  10  comprises a cylindrical cylinder housing  12  of a non magnetic zinc alloy, a cylinder  14  also of a non magnetic material mounted in the cylinder housing  12 , and a key socket  16  formed by a key contact plate  18  and part of the cylinder housing  12 . 
   Referring now to  FIGS. 2 and 3 , the cylinder housing  12  is formed by two half shells  12   a ,  12   b . The shells are held together by connectors comprising pins on the first half shell  12   a  (not shown) which are formed to be aligned and co-operable with holes  20   a ,  20   b  formed in the second half shell  12   b . The formed cylinder housing  12  has a collar  12   c  and a reduced diameter region  12   d  at one end which forms part of the key socket  16 . The cylindrical cylinder housing  12  has a longitudinal central axis  19 . The formed cylinder housing  12  further defines a pair of longitudinally axially spaced internal annular walls  22   a ,  22   b  positioned towards opposite ends of the cylinder housing. The annular walls  22   a ,  22   b  have circular openings  24   a ,  24   b  therein. The openings  24   a ,  24   b  are aligned with one another along a second longitudinal axis radially displaced from the longitudinal axis  19  of the cylinder housing  12 . The cylinder housing  12  further has a first annular groove  26  positioned adjacent the collar  12   c  and a second annular groove  28  within the key socket region  16 . 
   Referring now to  FIG. 4 , the cylinder  14  has first and second disc-like end regions  30 ,  32 , having axially inner  30   a ,  32   a  and outer  30   b ,  32   b  surfaces, which are spaced apart along a first cylinder longitudinal axis which, when the cylinder  14  is mounted in the cylinder housing  12 , is coincident with the longitudinal axis  19  of the cylinder housing  12 . The first and second end regions  30 ,  32  have first and second bores  34 ,  36  respectively therethrough which are coaxially disposed on a second cylinder longitudinal axis radially displaced from the first cylinder longitudinal axis. The second cylinder longitudinal axis is displaced such that the bores  34 ,  36  are in alignment with the circular openings  24   a    24   b  in the internal annular walls  22   a ,  22   b  of the cylinder housing  12  when the cylinder  14  is mounted therein. The first end region  30  further has a channel  38  extending across the diameter of the outer surface  30   b . The second end region  32  is further integrally formed with a latch operating member  40  extending from its outer surface  32   b . The cylinder  14  further comprises a central region- 42  which is cut away so as to define a chamber  44 . The chamber  44  has end walls  44   a ,  44   b -provided with openings  44   c ,  44   d  which are aligned with the bores  34 ,  36  in the first and second end regions  30 ,  32  respectively. The end walls  44   a ,  44   b  of the chamber and the inner surfaces  30   a ,  32   a  of the first and second end regions  30 ,  32  together define a pair of annular grooves  46   a ,  46   b  around the cylinder  14 . 
   Referring now to  FIGS. 1 and 2 , an electromagnetic coil  48  (only shown schematically), in the form of a winding around a soft iron core, having a length equal to that of the central region  42  of the cylinder  14 , and the same diameter as the bores  34 ,  36  in the end regions  30 ,  32 , is seated in the openings  44   c ,  44   d  in the walls  44   a ,  44   b  of the chamber  44  so as to align with the bores  34 ,  36  in the first and second end regions. The electromagnetic coil  48  is prevented from being longitudinally displaced by a pair of collars  48   a ,  48   b  which abut against the walls  44   a ,  44   b  of the chamber  44 , and is held in place by a cylinder cover  50 . The cylinder cover  50  has regions  50   a ,  50   b  which co-operate with the openings  44   c ,  44   d  in the walls  44   a ,  44   b  of the chamber  44  so as to lock the electromagnetic coil  48  in place. Space is also provided in the chamber  44  for the circuitry (not shown) required to operate the lock cylinder assembly  10 . This circuitry can provide the lock with a unique code or set of codes so that only insertion of a key carrying the correct validation code will result in activation of the lock. 
   First and second locking members are provided in the form of magnetic shuttles  52   a ,  52   b  having a hardened outer coating surrounding a hard magnetic core. The first magnetic shuttle  52   a  is positioned in the bore  34  in the first cylinder end region  30 , and the second magnetic shuttle  52   b  is positioned in the bore  36  in the second cylinder end region  32 . The shuttles  52   a ,  52   b  are of a diameter so as to form a close sliding fit with the bores  34 ,  36 , and of a length equal to the length of the end regions  30 ,  32  of the cylinder  14 . 
   The key contact plate  18  is made of tungsten carbide and has the same diameter as the cylinder  14 . The key contact plate  18  has a rib  18   a  on its rear surface to engage with the channel  38  in the outer surface  30   b  of the first end region  30 , and three electrical connections on its front surface  18   b  which can be electrically connected via the circuitry in the chamber  44  to the electromagnetic coil  48  allowing the coil to be energised. 
   In the assembled lock cylinder  10 , the inner annular walls  22   a ,  22   b  of the cylinder housing  12  co-operate with the corresponding annular grooves  46   a ,  46   b  in the cylinder  14 , and act to hold the cylinder  14  within the cylinder housing  12 . The openings  24   a ,  24   b  in the inner walls  22   a ,  22   b  of the cylinder housing  12  are of the same dimensions as the bores  34 ,  36  in the cylinder  14  with which they can be aligned. The key contact plate  18  abuts the outer surface  30   b  of the first end region  30  of the cylinder  14  when the rib  18   a  is seated in the channel  38 . The key contact plate  18  is held in position by the collar  12   c  on the cylinder housing  12 . A seal  54  is positioned on the key contact plate and held in place in the first groove  26  in the cylinder housing  12  to prevent dirt and moisture ingress into the lock cylinder assembly  10 . The key contact plate  18  acts to retain the first magnetic shuttle  52   a  in the first end region  30  of the cylinder  14 . The second magnetic shuttle  52   b  is retained in the second end region  32  of the cylinder  14  by an annular inner end plate  56  rotatable relative to the cylinder housing  12 . The inner end plate  56  has an opening  56   a  therein through which the latch operating member  40  extends and acts to prevent tampering and entry of dirt as well as acting as a support for the member  40  and retaining the second magnetic shuttle  52   b.    
   The key socket  16  allows a key (not shown) containing a power supply to engage with the key contact plate  18  so as to energise the electromagnetic coil  48  if the key is correctly coded. The second groove  28  acts in conjunction with a mechanical retention means on the key, to retain the key in place in the key socket  16  allowing it to be turned. Rotation of the key results in rotation of the key contact plate  18  and the cylinder  14  to operate the lock. 
   In use, a lock containing the lock cylinder-assembly  10  maintains a locked position until the electromagnetic coil  48  is energised by insertion of the correct key.  FIG. 1  shows the lock cylinder assembly  10  in its locked position in which the first and second bores  34 ,  36  in the cylinder end regions  30 ,  32  are aligned with the openings  24   a ,  24   b  in the internal walls  22   a ,  22   b  of the cylinder housing  12 . The first and second magnetic shuttles  52   a ,  52   b  are attracted by their own magnetic fields to the soft iron core of the de-energised electromagnetic coil  48  and take up positions such that they extend from the end regions  30 ,  32  and across the annular grooves  46   a ,  46   b . In this position the first and second magnetic shuttles  52   a ,  52   b  extend into the openings  24   a ,  24   b  in the internal walls  22   a ,  22   b  of the cylinder housing  12 . This results in the cylinder  14  being locked against rotation relative to the cylinder housing  12  by the first and second magnetic shuttles  52   a ,  52   b  which, when a rotational force is applied, engage the internal walls  22   a ,  22   b  of the cylinder housing  12  and the end regions  30 ,  32  of the cylinder  14 . 
   Upon insertion of a key into the key socket  16  an electrical connection is made between the key and the electrical contacts  18   b  on the key contact plate  18 . This results in a signal being passed to the circuitry in the chamber  44 . If the signal is validated by the circuitry, current from the key is passed to the electromagnetic coil  48  which is then briefly energised. Energising the electromagnetic coil results in the generation of a magnetic field of a strength and direction to cause the magnetic shuttles  52   a ,  52   b  to be repulsed so that they no longer extend into the annular grooves  46   a ,  46   b  in the cylinder  14  and are situated fully within the end regions  30 ,  32  of the cylinder  14 . The obstruction to relative rotation of the cylinder  14  within the cylinder housing  12  is removed and the cylinder  14  is then freely rotatable within the cylinder housing  12  by rotation of the-key, the key being releasably held in the key socket  16  by a mechanical key retention means (not shown) such as a spring loaded ball detent. Rotation of the cylinder  14  rotates the integrally formed latch-operating member  40  and opens the lock. The electromagnetic coil  48  remains energised only for sufficient time for the cylinder  14  to be rotated away from its locked position, and will not be re-energised until the key is removed and reinserted. Upon rotation of the cylinder  14  the bores  34 ,  36  in the end regions  30 ,  32  in which the shuttle members  52   a ,  52   b  are positioned become misaligned with the openings  24   a ,  24   b  in the internal walls  22   a ,  22   b  of the cylinder housing  12 . In this position, when the electromagnetic coil  48  is de-energised the magnetic shuttles  52   a ,  52   b  cannot return to their locked position under the influence of their magnetic fields. Upon closure of the lock, the bores  34 ,  36  in the cylinder end regions  30 ,  32  and the openings  24   a ,  24   b  in the internal walls of the cylinder housing  12  become realigned. The magnetic shuttles  52   a ,  52   b  re-enter the annular grooves  46   a ,  46   b  through the openings  24   a ,  24   b  under the influence of their magnetic fields and lock the cylinder  14  against rotation within the cylinder housing  12 .