Patent Publication Number: US-2007113605-A1

Title: Magnetically controlled locking device

Description:
The invention relates to an improved magnetically controlled locking device.  
      European Patent Application EP-A-633 375 discloses a magnetically controlled locking device comprising a key and a cylinder. This cylinder comprises a stator and a rotor, the latter being set in rotation about a longitudinal axis of the cylinder by the key. The cylinder bears a plurality of magnets oriented in a direction globally parallel to the axis of rotation of the rotor. These magnets cooperate with other magnets distributed opposite in a part of the key. These magnets are clasped in bushings made of ferromagnetic metal. The bushings bearing the magnets located in the cylinder are mobile in translation inside housings of complementary shape.  
      When that part of the key bearing the magnets is presented opposite the magnets of the corresponding part of the rotor, these latter attract or repel depending on the polarities and respective positions of the magnets borne by the key and the cylinder. In this way, the key induces the displacement, towards the bottom of the corresponding housing or in the direction of the opening of this housing, of the bushings located in the cylinder. Such displacement has for consequence respectively to unlock the rotor and to allow its rotation or to block it in rotation. The rotor is associated with a member, for example an eccentric mounted on its rotational spindle, which may displace a slide block which actuates a bolt in a keeper.  
      When the magnetic axes of two magnets, borne by the cylinder and by the key, merge and depending on whether their extremities opposite each other form identical or inverted magnetic poles, they repel or attract each other. On the other hand, if the magnetic axes of these magnets are slightly offset, i.e. if the longitudinal axes of the magnets are parallel and/or non-merged, the extremities of the magnets opposite each other and of identical magnetic poles, do not repel but attract each other. This is due to the fact that the magnets are clasped in ferromagnetic bushings which channel the magnetic flux and behave, in a zone of their wall and in contact with a pole of the magnet clasped in the bushing, like a magnetic pole inverse of the pole of the magnet.  
      In this way, by playing on the number of magnets, their polarities and their relative positions, a plurality of associations between the magnetic poles of the magnets of the key and of the cylinder are very easily obtained. The magnets thus attract or repel depending on their implantation, while allowing a coding of the locking device. With such a device, the contact of the respective extremities of the magnets of the cylinder and of the key is effected thanks to the adjacency of terminal parts of the rotor and of the key. These terminal parts are planar metal pieces provided with a simple device for guiding and positioning the key opposite the rotor, for example one or more studs penetrating in one or more impressions.  
      One of the principal difficulties of such a devices resides in the limited number of combinations enabling devices to be produced which can be maneuvered by general or partial pass-keys or in varied structures.  
      Furthermore, if it is desired to increase the possibilities of combinations between the magnets of the key and of the cylinder for a given matrix, and thus increase the potential number of devices in operation while preserving a unique coding for each, it is indispensable to be able to play on the number and the magnetic moment of the magnets employed in the device.  
      Now, for practical and economic reasons, it is not desirable to increase unduly the size of the device, and particularly that of the key, in order to house more magnets.  
      It is a more particular object of the invention to overcome these drawbacks by proposing a magnetically controlled locking device presenting an increased inviolability and of which the positioning of the bushings bearing the magnets is precise and reliable, while allowing a number of combinations greater than that of the known device.  
      To that end, the invention has for its object a magnetically controlled locking device comprising a cylinder provided with a stator and a rotor, the rotor being adapted to be rotated about a longitudinal axis of the cylinder thanks to a key, the latter being equipped with magnets clasped in bushings made of ferromagnetic material and adapted to cooperate with other magnets likewise clasped in bushings made of ferromagnetic material, mounted to slide in at least a part of the cylinder so as to be able selectively to lock the rotation of the rotor, these magnets, respectively borne by the key and the cylinder, being of the same geographical distribution, characterized in that at least two bushings located respectively in the key and the cylinder each clasp and maintain two magnets of inverted polarity with respect to each other or a magnet provided with at least one bipolar extremity.  
      Thanks to the invention, a device is produced where the presence of two magnets of inverted polarity, or of one magnet provided with at least one bipolar extremity, per bushing makes it possible to multiply the number of combinations possible, all the more so as one can play on the various relative angular positions of the magnets between them. By maintaining the angular position, the relative positioning of the magnets of the cylinder and the key is ensured precisely and constantly in time. The precision of the “geographical” register between the magnetic bushings borne by the rotor and those borne by the key is optimized. In effect, a slight angular or radial displacement of a magnet may modify the value of reception of the magnetic fluxes between the magnets of the rotor and the key, and even invert the direction of the magnetic flux. This angular or radial deviation may go as far as preventing the displacement of the bushing of the cylinder in translation. This has for consequence a blocking of the system, the key no longer corresponding defacto to the “magnetic code” of the cylinder, which securitizes the device against any non-authorized attempt at manceuvre.  
      According to advantageous but non-obligatory aspects of the invention, the locking device incorporates one or more of the following characteristics: 
          each bushing is adapted to maintain the two magnets or the magnet provided with at least one bipolar extremity that it clasps in a given angular position with respect to a longitudinal axis of the bushing.     the angular position of the magnet provided with at least one bipolar extremity or of the two magnets clasped in the same bushing is maintained by the fact that the magnets are immobilized in the bushing by the cooperation of at least one member for blocking in rotation located on an outside wall of the bushing adapted to cooperate with a member of complementary shape located on an inside wall of a housing for receiving this same bushing. The blocking member is advantageously a finger, a stud or a slideway. The member of shape complementary to the blocking member is, respectively, a slideway, a finger or a stud.     The bushings and the magnets or the magnet provided with at least one bipolar extremity, are of non-circular section.     The magnet provided with at least one bipolar extremity or the two magnets of inverted polarity, clasped in the same bushing, have magnetic moments of the same intensity and of opposite directions. In a variant, these magnetic moments are of different intensities and of opposite directions.     The bushings located on the cylinder are mobile in translation in housings, while the bushings located on the key are immobile in their housings.     The parts of different polarities of a magnet provided with at least one bipolar extremity or of the magnets clasped in each bushing of the cylinder have magnetic moments of the same intensity and of opposite directions. In a variant, these magnetic moments are of different intensities and of opposite directions.     The magnets of the cylinder and of the key are anisotropic. In a variant, they are isotropic.        

      The invention also relates to a means for obturating an opening or an access provided with a locking device made in accordance with any one of the above-defined characteristics.  
      Thanks to the invention, the quality of the relative positioning of the magnets is ensured, this being primordial taking into account the size of such magnets. With such a configuration, one also dispenses with the clearance between the bushing and its housing, this clearance generating a risk of rotation of the bushing in its housing. 
    
    
      The invention will be more readily understood and other advantages thereof will appear more clearly on reading the following description of a form of embodiment of a locking device according to the invention, given solely by way of example and made with reference to the accompanying drawings, in which:  
       FIG. 1  is a view in perspective of a locking device according to the invention, the cylinder being in place in a partially shown door, the key being represented ready to be engaged in the device.  
       FIG. 2  is a view in perspective of the key.  
       FIG. 3  is a view in perspective, with parts torn away, of a part of the cylinder, the rotor being in locked position.  
       FIG. 4  is a view similar to  FIG. 3  with the rotor in unlocked position.  
       FIGS. 3A and 4A  are schematic partial sections, on a larger scale, along plane IIIA of the device, in locked position without the key and unlocked with the key in place, respectively.  
       FIGS. 5 and 6  schematically show the different forces of attraction and of repulsion between the magnets borne by bushings located respectively in the key and in the rotor depending on the alignment or non-alignment of their respective magnetic axes.  
       FIGS. 7 and 8  are partial views in perspective illustrating two forms of embodiment of the blockage in rotation of a bushing in its housing.  
       FIG. 9  schematically shows the various possibilities of geometric distribution of the magnets of the cylinder, such distributions being transposable to the key.  
       FIG. 9A  is a view similar to a part of  FIG. 9  for a bushing equipped with a single magnet whose extremity is bipolar.  
       FIG. 10  schematically shows another type of insertion of two magnets of inverted polarity in a bushing, and  FIG. 11  schematically shows other possible geometric configurations for the bushings. 
    
    
      The device  1  shown in  FIG. 1  comprises a front face  2  apparent on a face  3  of a door. This front face is made of metal, for example steel, and is fitted on the door so as to offer no interstice or clearance that might be used for “forcing” the device  1 . The front face  2  is in the form of a dome with circular base of which the apex  4  is truncated. This apex  4  is formed by a plane, smooth, circular plate. It is provided in the vicinity of its periphery with two diametrally opposite studs  5 . These studs  5  have the shape of two cylinders of small dimensions of which the longitudinal axis is oriented in a direction globally perpendicular to the plane of the face  3 . They present a shape adapted to be inserted in impressions  6  located on a plane face  7  of a key  8 . This face  7  is solid, smooth and its shape and dimensions are complementary to those of the apex  4 . The introduction of the studs  5  in the impressions  6  makes it possible to position the key on the plate  4  of the device.  
      The zones  4  and  7  in contact correspond to the outer surfaces of the extremities of the key  8  and of the rotor  9 . In this way, contact and cooperation between the part of the device  1  fixed in the door and the part of the key ensuring the mancuvre is effected by the superposition of two smooth, planar surfaces  4  and  7 . Behind these surfaces  4  and  7  are located magnets  10   b  and  10   c . These magnets  10   b  and  10   c , in the form of a bar, are disposed so that their magnetic axes are oriented in a direction globally parallel to a central axis CC′ of the apex  4 . They are located, both those adjacent the plate  4  and those adjacent the surface  7 , so that one of their magnetic poles is in contact with one of these surfaces. The magnets  10   b  and  10   c  are geographically distributed in the same manner in the rotor  9  and the key  8  with the result that the magnetic pole of a magnet  10   b  located in the rotor  9  can act only on the magnetic pole of one sole complementary magnet  10   c  housed in the key  8 .  
      The body of the key  8  is in the form of a cylinder, visible in  FIG. 2 , of short length with respect to the diameter of its base. This base is formed by the face  7  of the key bearing the impressions  6 . The extremity opposite this face  7  bears a means for gripping the key in the form of a palette  11 , shown in  FIG. 2 .  
      The locking device  1  comprises in particular a cylinder  12  of hollow cylindrical shape housing a stator  14  provided with a plurality of tubular housings  15 , with identical circular bases. The stator  14  is located in a region of the cylinder remote from the plate  4 . In this way, the stator  14  is located in that part of the cylinder  12  set in the door. The housings  15  have an open extremity flush with the face  16  of the stator  14  in contact with a rotor  9 . The latter has a cylindrical shape similar to that of the stator  14 . It is also provided with a series of housings  17  of shapes and diameters identical to the housings  15  of the stator. The housings  17  are made in the rotor so as to extend, over the whole length of the rotor  9 , the housings  15  of the stator  14 . They are open at their two extremities.  
      A rotational spindle  18  is positioned in a direction globally merged with the longitudinal and central axis AA′ of the cylinder  12 . This spindle  18  is fast with the rotor  9  and mounted to rotate freely in a through orifice made over the length of the stator  14 . O-rings  26  located on the outer wall of the rotor ensure seal. The rotor is also provided with a so-called “anti-boring” device (not shown).  
      The housings  15  each comprise a return spring  19  at the level of their blind extremities located in the stator  14 . These housings  15  house bushings  20   b  in each of which two magnets  10   b   1  and  10   b   2  are inserted and immobilized for example by gluing. The central longitudinal axis BB′ of these bushings is globally parallel to the axis AA′ of the cylinder. As shown in  FIG. 7 , the bushings  20   b  are provided, on the outer radial surface  21  of their wall, with a finger  22 . The latter is adapted to be inserted in a groove  23  of complementary shape made in the inner face  24  of the wall of a housing  17  and forming slideway for the finger  22 . This groove  23  is made over the whole length of the housing  17  and oriented in a direction globally parallel to axis BB′.  
      In a variant shown in  FIG. 8  which concerns a bushing  20   c  mounted in the key  8  and clasping two magnets  10   c   1  and  10   c   2 , a finger  22 ′ is borne by the inner face  24 ′ of a housing  17 ′ made in the key  8 . In this configuration, it is the outer face  21 ′ of the wall of the bushing  10   c  which bears a complementary groove  23 ′.  
      In practice,  FIGS. 7 and 8  may concern the bushings  20   b  and  20   c  equally well.  
      For the bushings  20   c  shown in  FIG. 8 , the grooves  23 ′ ensure only the blocking of the fingers  22 ′ in rotation and do not have the function of forming a slideway for a bushing  20   c . The latter are immobilized in their housings  17 ′.  
      Two magnets  10   b   1  and  10   b   2  of inverted polarities and preferably anisotropic, i.e. being able to be magnetized only in a preferential direction, are clasped in each bushing  20   b . As shown in the upper part of  FIG. 9 , these two magnets  10   b   1 , and  10   b   2  may be in the form of two half-cylinders of the same dimensions. In the same bushing  20   b , there may also be one magnet  10   b   2  representing, in cross section, three-quarters of a disc and another magnet  10   b   1  representing a quarter of a disc as is visible in  FIGS. 3, 4 ,  7 ,  8 ,  9 A and in the lower part of  FIG. 9 . These two configurations may be presented simultaneously and in any proportions and distribution in the same locking device  1 .  
      In the same way, a bushing  20   c  bears two magnets  10   c   1  and  10   c   2  which may be in the form of two identical half-cylinders or a magnet  10   c   2  representing in cross section three quarters of a disc, the other magnet  10   c   1  forming a quarter of a disc.  
      The precise positioning of a bushing  10   b  in its housing, thanks to the finger  22  and to the groove  23 , makes it possible to “pair off” the magnets  10   b   1  and  10   b   2  of the rotor  9  and those  10   c   1  and  10   c   2  of the key  8 , in one of the different positions shown in  FIG. 9 . As shown in  FIG. 9A , a single magnet  10   b ′ may be immobilized in a bushing  20   b ′ of the cylinder. This magnet  10   b ′ is bipolar at least at the level of its extremity turned towards the front face  2 . Similarly, magnets of which one face is bipolar may be provided in the bushings  10   c  of the key  8 . The two zones  10   b′   1  and  10   b′   2  of inverted polarity of the extremity of the magnet  10   b ′ visible in  FIG. 9A  perform a role similar to the one envisaged hereinabove for the magnets  10   b   1  and  10   b   2 .  
      In another form of embodiment shown in  FIG. 10 , magnets  10   b   1 ,  10   b   2  or  10   c   1 ,  10   c   2  are in the form of two concentric cylinders, one, hollow, forming a peripheral magnet of polarity inverse of the solid one forming a central magnet. In this case, the means for angularly positioning the magnets are not indispensable.  
      In another form of embodiment shown in  FIG. 11 , the bushings  10   b ,  10   c  present a non-circular cross section. This section is for example rectangular, triangular, polygonal or oval. With such shapes of bushings, there is no more need for a means for blocking in rotation when these bushings are positioned in their respective housings.  
      The magnets  10   b   1 ,  10   b   2 ,  10   c   1  and  10   c   2  act in repulsion or in attraction depending on their alignments, their angular positions and their polarities. In position of rest, shown in  FIG. 3A , a return spring  19  located in the closed end of a housing  15  pushes a piston  25  which displaces the magnets  10   b , and  10   b   2  of the rotor  9  towards the opening of the housings  17 .  
      This piston  25  is positioned in the housing  15  between the spring  19  and the bushing  20   b . The length of the piston  25  is adapted to the return force of the spring  19  inserted in a given housing  15 .  
      In fact, these pistons  25  displace the bushings  20   b  located in the housings  17  so that said bushings come, at the end of stroke, in contact with the surface  4  of the device  1 . In this configuration, the pistons  25  are positioned both in part in the housings  17  of the rotor  9  and in part in the housings  15  of the stator  14 . They then block the rotor  9  in rotation.  
      Certain housings  15 , visible in  FIGS. 3 and 4 , do not house any spring  19 . In that case, the piston  25  forms a member for translatory abutment for the movement of a bushing  20   b  moving in the housing  17  towards the housing  15  located in its extension. The displacement of the bushing  20   b  is induced by the attraction of a magnetic pole of the magnet  10   b   1  or  10   b   2 , immobilized in the bushing  20   b , by the metallic end of the piston. The length of the piston  25  is adapted so that, when the bushing  20   b  is in abutment on the piston  25 , it straddles the zone of join between the stator  14  and the rotor  9 .  
      In this position, the pistons  25  and/or the bushings  20   b  make it possible to block the rotor  9  in rotation. In this way, the device remains locked.  
      When the key  8  is presented opposite the plate  4 , care being taken to insert the studs  5  in the impressions  6 , there is register between the magnets  10   b   1 ,  10   b   2 ,  10   c   1  and  10   c   2  of the rotor  9  and of the key  8  located on either side of the plate  4  and the face  7 . As shown in  FIGS. 4 and 4 A, depending on their polarity, the magnets  10   c   1 ,  10   c   2  of the key  8  repel or attract the magnets  10   b   1 ,  10   b   2  set in the bushings  20   b . In this way, the pistons  25  are disengaged from the zone of join between the stator  14  and the rotor  9 . Disengagement is obtained, in that case, by compression of the springs  19  under the action of the pistons  25  pushed back in the direction of the bottom of the housings  15  by the bushings  20   b.    
      In the second case of bushings  20   b  being located opposite the housings  15  having no spring  19 , these bushings  20   b  are attracted in the direction of the plate  4  by the magnets  10   c   1 , and  10   c   2  of the key  8  and are totally housed in the housings  17  of the rotor  9 .  
      In this way, the rotor  9  is unblocked in rotation and this movement, generated by the key  8  on the rotor  9 , also makes it possible to rotate the spindle  18 , and therefore the system of linkage with the keeper and the bolt of the door, in order to be able to open the latter.  
      With such a device, it is easy to multiply the number of possible combinations by playing on the angular position of the magnets and/or the intensity of the magnetic moments as well as on the lengths of the pistons  25  and the springs  19 .  
      For example, for a cylinder  12  and a key  8  of which the surfaces  4  and  7  each have a diameter of about 15 millimetres, a geographical distribution of six bushings  20   b ,  20   b ′,  20   c  with a unitary diameter of 3 millimetres can be imagined. By playing on the intensity of the magnetic moment and on the angular position of each bushing  20   b ,  20   b ′,  20   c , possible associations of polarity of the magnets  10   b   1 ,  10   b   2 ,  10   b′   1  and  10   b′   2  of the rotor  9  and of the magnets  10   c   1  and  10   c   2  of the key  8 , greater than twenty million, are attained.  
      The invention has been described with reference to forms of embodiment where all the bushings clasp and maintain two magnets. It may in fact be that only certain bushings clasp and maintain two magnets.  
      In another configuration, the magnets do not occupy all the interior volume of a bushing  20   b ,  20   b ′ or  20   c . The remaining volume may be filled with an a magnetic or ferromagnetic material.  
      In another form of embodiment, the displacement of the rotor is no longer effected in rotation about the longitudinal axis AA′ of the cylinder, but in translation in a direction globally perpendicular to axis AA′.