Abstract:
The present invention relates to a coupling gear device for entraining a shaft door by means of an elevator car door that can be actuated by a door drive for elevator devices, comprising entrainment means ( 110 ) provided on the side of the elevator car door and counter entrainment means ( 210 ) arranged on the side of the shaft door. The counter entrainment means can be acted on by the entrainment means ( 110 ) for entraining the shaft door, wherein the entrainment means ( 110 ) and/or the counter entrainment means ( 210 ) can be lowered at least partially in the elevator car door or the shaft door.

Description:
RELATED APPLICATIONS 
     This application is a continuation of PCT Patent Application Serial No. PCT/EP2010/061911, filed Aug. 16, 2010, which claims priority to European Patent Application 09179529.4, filed Dec. 16, 2009, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates to a device for entraining a shaft door by means of a lift car door according to the preamble of claim  1 . A device of this type is also called a coupling gearing. 
     Lift doors usually have a door provided on the lift car as well as shaft doors provided at each floor. When the lift car approaches a floor, it is necessary for both the lift car door and the corresponding shaft door (then positioned behind the lift car door) to be opened and closed to allow passengers to get into and out of the lift and to allow the lift car to continue on its way. 
     A lift car door usually has a drive by which it can be opened and closed. To avoid corresponding drives for every shaft door, the lift car door is configured with a catch or entrainment mechanism which, when the lift car arrives at a floor, engages in a corresponding counter-catch of the shaft door and also opens and closes the shaft door. In this respect, expanding hook bolt mechanisms are usually used, as described, for example, in EP 0 744 373 B1. 
     A disadvantage of the mechanism described in that document is that when the lift car moves, the catch and counter-catch project into the threshold spacing, i.e. into the spacing between shaft door threshold and lift car door threshold, which can result in rattling and wind noises when the lift car moves relatively fast, because for example when passing through a floor (without stopping), the catch and counter-catch are moved very closely past one another. In other words, the effective spacing between lift car door and shaft door is significantly smaller than the threshold spacing. 
     In particular in the case of a so-called high-power lift car door, it is essential to prevent rattling and wind noise at very fast travelling speeds. Furthermore, lift doors of this type are to open and close as fast as possible. 
     SUMMARY OF THE INVENTION 
     The present invention proposes a device (coupling gearing device) It is considered to be a particular advantage of the device according to the invention that the threshold spacing between shaft door and lift car door can be substantially utilised in an optimum manner due to the provided displaceability of the catch means and the counter-catch means, arranged on the lift car side and/or on the shaft side, during the travel of the car, in particular when passing through a floor without stopping. 
     The provided mechanism also proves to be actuatable in a fast and reliable manner, thereby ensuring a fast opening and closing of the lift car door and shaft door. Thus, the device according to the invention is a highly effective coupling gearing for lift car door and shaft door. 
     Advantageous configurations of the device according to the invention are the subject matter of the dependent claims. 
     According to a particularly preferred embodiment of the device according to the invention, the catch means are configured to be extensible and can be at least partly submerged into the shaft door to act upon the counter-catch means. This construction allows a particularly simple configuration of the counter-catch means, it being possible at the same time for the threshold spacing, i.e. the distance between lift car door threshold and shaft door threshold to be maximised. 
     The catch means on the lift car door side are expediently configured as expander skates expander skate angles. Expander skate angles of this type have a sufficient longitudinal extension such that it is possible to realise a relatively great tolerance range with respect to the position of the lift car on initiating the coupling between shaft door and lift car door. 
     The counter-catch means on the shaft door side are preferably configured as rollers. Rollers of this type prove to be unsusceptible to rattling and require little maintenance. 
     The device according to the invention expediently has a locking mechanism which cooperates with the counter-catch means to lock the shaft door, it being possible for the locking mechanism to be unlocked when the catch means acts on the counter-catch means. A locking mechanism of this type is usually prescribed by law. Locking and unlocking operations using the device provided according to the invention proves not to be complex in mechanical terms. 
     When the catch means act on the counter-catch means, the catch means are expediently initially moved vertically and then parallel to the threshold leading edges of the lift car door and shaft door. It is possible to realise movements of this type in a particularly simple manner by the mechanism portrayed in the description of the figures. 
     For this purpose, the device according to the invention preferably has a carriage on the lift car side which can be moved on a lift car door by a drive, said carriage being configured with rollers which are moved during displacement by a connecting link of a guide unit, the catch means being coupled with the guide unit such that a movement of the rollers by the connecting link results in the catch means extending with respect to the lift car door. A mechanism of this type with a displaceable carriage, the rollers of which can be moved by a connecting link, permits a very precise and reliable mobility of the catch means, in particular of the expander skates. The drive is preferably configured as a belt drive, for example with a toothed belt, as a cable pull, a spindle drive or as a purely electrical drive, for example a linear motor. 
     The drive which is used is preferably configured to be self-locking or non-self-locking. As a result of providing self-locking means, for example by providing corresponding inclination angles and/or surface roughnesses in the case of a spindle drive, it is possible to prevent an automatic or self-acting coupling of lift car door and shaft door. For specific requirements, for example in emergencies, it can also be advantageous to do without such a self-locking so that the lift car door and shaft door can engage with one another even if a power failure occurs. If an engagement of this type is always guaranteed during a power failure, then opening the doors, for example for rescue services, is also simplified. 
     In particular, a drive used according to the invention can also be configured to be programmable, so that adapting, for example to mechanical characteristics of the device, for example in the form of connecting links and/or restricted guidance means, is possible. 
     This mechanism also advantageously has a driver (engaging element) which is provided on the carriage and which, upon a further movement by the carriage, acts on a lever, configured on the catch means, thereby causing the catch means to spread apart. A spreading apart of two expander skate angles arranged substantially parallel by a lever mechanism of this type proves to be very precise, and simultaneously ensuring a mechanical robustness. In this respect, it is particularly advantageous for the lever to be configured with corresponding means, for example with rollers which allow mobility in a corresponding connecting link. 
     The device according to the invention is characterised, inter alia, in that a one-dimensional movement provided by a drive can be converted into a complex movement, i.e. into a movement which acts in a plurality of directions by mechanical means, in particular by the mentioned connecting links or restricted guidance means. The mechanical means provided according to the invention prove to be reliable and maintenance-free. 
     According to a particularly preferred embodiment of the invention, a lift car door lock on the lift car door side is provided which can be actuated by actuating means provided on the shaft door side. A lift car door locking mechanism of this type ensures that the lift car door can only be opened when it is aligned relative to a shaft door, i.e. when the lift car is located at a floor. The mechanism provided according to the invention for locking the lift car door is characterised in that it is configured such that, corresponding to the catch means, it can be extended relative to the shaft door. Thus, a lift car door lock is also ensured according to the invention, while guaranteeing a maximum threshold spacing between the lift car door and the shaft door. 
     In a particularly advantageous manner, the lift car door lock is configured together with the catch means to be extensible. In particular, this means that some of the components of the lift car door lock utilise the movement of the catch means (i.e. they follow said movement) in order, for their part, to extend relative to a shaft door. Therefore, the lift car door lock does not require its own drive. In this respect, some of the components of the lift car door lock are configured such that they cannot be extended, while further components create the extensibility of the lift car door lock. 
     According to a particularly preferred embodiment, the lift car door lock has a hook bolt, a connecting rod and a locking lever, these elements being configured to be non-extensible, and also has a driving roller, a driving lever and a locking skate angle, these elements being configured to be extensible. In utilising the extension and widening movement of the catch means, a mechanism of this type proves to be mechanically sturdy, satisfying highest safety requirements. 
     In a particularly advantageous manner, a lift comprises a device according to the invention. 
     It is understood that the features which have been mentioned above and those which will be described in the following can not only be used in the combination stated in each case, but also in other combinations or on their own, without thereby departing from the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective general view of a first preferred embodiment of the components or catch (engaging) means on the lift car side of a device according to the invention, 
         FIGS. 2   a  to  2   c  are views of the catch means according to  FIG. 1  from above, in each case in different operating positions, together with a preferred embodiment of the counter-catch means on the shaft door side, 
         FIGS. 3   a  to  3   c  are side views corresponding to the operating positions of  FIGS. 2   a  to  2   c , but with only the catch means on the lift car side being shown, 
         FIG. 4  is a view, corresponding to  FIG. 1 , of a further preferred embodiment of the components or catch means on the lift car side of a device according to the invention, 
         FIGS. 5   a  to  5   c  are views, corresponding to  FIGS. 2   a  to  2   c , of the catch means according to  FIG. 4  together with a preferred embodiment of the counter-catch means on the shaft door side, 
         FIGS. 6   a  to  6   c  are side views or plan views corresponding to the operating positions of  FIGS. 5   a  to  5   c , but with only the catch means on the lift car side being shown, 
         FIG. 6   a ′ to  6   c ′ are plan views corresponding to the operating positions of  FIGS. 6   a  to  6   c,    
         FIGS. 7   a  to  7   c  are views, corresponding to  FIGS. 5   a  to  5   c , of a further preferred embodiment of the device according to the invention, 
         FIGS. 8   a  to  8   c  are views, corresponding to  FIG. 6   a ′ to  6   c ′ of the embodiment according to  FIGS. 7   a  to  7   c , and 
         FIGS. 9   a  to  9   c  are partial views, corresponding to  FIGS. 6   a  to  6   c  of the embodiment according to  FIGS. 7   a  to  7   c.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The illustrated first embodiment of the device according to the invention is identified overall by reference numeral  100  in  FIGS. 2   a  to  2   c.    
     The device  100  serves to couple a lift car door with a shaft door of a lift. The lift car door and shaft door are only shown schematically in  FIGS. 2   a  to  2   c  by means of parentheses and are identified by reference numeral  80  and respectively 90. By means of the coupling provided by the device  100  between lift car door  80  and shaft door  90 , only the lift car door  80  has to be configured with a door drive (not shown) which opens and closes the lift car door. By virtue of the coupling, the respective shaft doors do not have to be provided with their own drives. 
     The device  100  has on the lift car door side two expander skate angles  110  which cooperate with rollers  210  attached on the shaft door side for coupling the lift car door and shaft door, as described later on. Thus, the expander skate angles  110  constitute catch means and the rollers  210  constitute counter-catch means in the context of the invention. 
     The device  100  also has on the lift car door side a drive  101  (see in particular  FIG. 1 ) which is connected to a carriage  102  and is used to move this carriage  102  upwards and downwards on the lift car door. 
     The carriage  102  is connected to the lift car door (not shown in  FIG. 1 ) by means of an axial mounting  107  and exclusively follows the upwards and downwards movement of the drive  101 . 
     A downwards movement of the carriage  102  causes the expander skate angles  110  to extend (i.e. a displacement in the direction of the shaft door, see arrow P 1  in  FIG. 2   b ) and to widen (expand) (i.e. a pushing-apart movement parallel to the shaft door, see the double arrow P 2  in  FIG. 2   c ) whereas conversely the upwards movement causes the expander skate angles  110  to fold and retract, as will be explained in more detail in the following. 
     The carriage  102  is configured with rollers  108 . These rollers  108  are attached to the carriage  102  and follow the upwards and downwards movement of the carriage  102 . During this upwards and downwards movement, the rollers  108  travel along a connecting link  109   a  of a guide unit  109 . The connecting link  109   a  has a first inclined portion  109   b  and a second flat portion  109   c.    
     A base body  110   a  of the expander skate angles  110  is attached to the guide unit  109 . The axial mounting  107  is rigidly connected to the lift car door, so that the guide unit  109  is freely mounted on the lift car door in the axial direction. 
     At least one expander skate angle  110  is configured with a lever  104  which, during a downwards movement of the carriage  102 , is acted upon by a driver  103  provided on the carriage  102 . 
     The mode of operation of the illustrated device  100  for extending, widening, folding and retracting the expander skate angles  110  is described in the following: 
     Starting from the position shown in  FIG. 1  and in  FIGS. 2   a  and  3   a , the drive  101  initiates the downwards movement of the carriage  102  along the lift car door. The rollers  108  attached to the carriage  102  follow the downwards movement of the carriage  102 , the rollers  108  travelling along the connecting link (or slotted element)  109   a  of the guide unit  109 . 
     The rollers  108  initially travel along the inclined portion  109   b  of the connecting link  109   a . The system consisting of expander skate angles  110  and guide unit  109  is released by the inclined portion  109   b  during the downwards movement of the carriage  102  so that the expander skate angles can be extended against the force of springs  105  provided on the mounting  107 , i.e. in the direction of the rollers  210  on the shaft door side illustrated in  FIGS. 2   a  to  2   c.    
     By means of the illustrated configuration of the mounting, which is flexible due to the springs  105 , of the expander skate angles  110  with respect to the lift car door, not only is the extension (and retraction) of the expander skate angles  110  possible, but so is a yielding of the expander skate angles  110  in the event of a collision with lift components provided on the shaft side. For this purpose, the connecting links  109   a  have widenings  109   d  in their lower region. Such collisions are possible, for example if the expander skate angles  110  extend prematurely due to a possible faulty operation. 
     When the rollers  108  have reached the transition from the inclined portion  109   b  to the flat portion  109   c  of the connecting link  109   a , the expander skate angles  110  are fully extended. This state is shown in  FIGS. 2   b  and  3   b . It can be seen from  FIG. 2   b  that the expander skate angles  110  are in this case (substantially) completely positioned between the rollers  210  of the shaft door. 
     During a further downwards movement of the carriage  102  and of the rollers  107  provided thereon, the rollers  108  move along the flat part  109   c  of the connecting link  109   a . A further extension of the expander skate angles  110  is now not possible in this case. The widening movement of the expander skate angles  110  relative to one another is initiated during this part of the downwards movement. 
     For this purpose, during this further downwards movement, the driver  103  attached to the carriage  102  entrains a lever  104  of the respective expander skate angles, and thus initiates the expansion process. The two expander skate angles  110  which are each connected to the expander skate base body  110   a  by this lever  104  spread apart. This state is shown in  FIGS. 2   c  and  3   c . In this state, the lift car door and shaft door are coupled together by the coupling of expander skate angles  110  and rollers  210  such that an opening and closing of the lift car door by a drive (not shown) results in an entrainment, that is to say a simultaneous opening and closing of the shaft door. 
     The expansion process has ended when the drive  101  concludes the downwards movement, i.e. when the rollers  108  have reached the lower end point in the connecting link  109   a.    
     In order to release the coupling between the lift car door and the shaft door, the described process has to be carried out in the reverse sequence. This is achieved by a corresponding upwards movement of the carriage  102  driven by the drive  101 . 
     During the upwards movement, the carriage  102  slides upwards and the rollers  108  initially travel along the flat portion of the connecting link  109   a . During this upwards movement, the contact between the respective levers  104  of the expander skate angles  110  and the driver (engaging element)  103  of the carriage  102  is released. As the result of a defined force which can be realised, for example as a spring, a weight or a forced entrainment, the expander skate angles  110  fold together again and once again reach the state shown in  FIGS. 2   b  and  3   b.    
     By moving the rollers  108  upwards along the inclined portion  109   b  of the connecting link  109 , the expander skate angles  110  are then moved again into the position shown in  FIG. 1 ,  FIG. 2   a  and  FIG. 3   a . The force provided by springs  105  during extension then has to be overcome. It is pointed out in this connection that the defined force for extending the expander skate angles  110  does not necessarily have to be provided by means of a spring  105 . Constructions with weights or restricted guidance means are also conceivable. 
     When the rollers  108  have reached the upper end of the connecting link  109   a , the expander skate angles  110  are again folded and retracted, i.e. they are in their original state. 
     In the following, a further embodiment of the device according to the invention is illustrated with reference to  FIGS. 4 to 6 . This device substantially corresponds in functionality to the device described above. The same or similar components have been provided with the same reference numerals so that the above description can be applied analogously. In the following, essentially differences compared to the first embodiment described above will be described. 
     The device according to  FIGS. 4 to 6  also has on the lift car door side two expander skate angles  110  which cooperate with rollers  210 , attached on the shaft door side, for coupling the lift car door and the shaft door. 
     A carriage  102  configured with rollers  108  is also provided analogously to the first embodiment described above. A drive, as denoted according to the first embodiment by reference numeral  101 , for moving the carriage  102  upwards and downwards on the lift car door, is not shown. 
     The connecting links  109   a  which are configured in an analogously provided guide unit  109 , along which the rollers  108  travel during the upwards and downwards movement of the carriage  102 , are configured overall with a uniform curvature compared to the first embodiment described above, thereby producing a more even extension movement of the expander skate angles  110  in the direction of the shaft door. 
     According to this embodiment as well, the expander skate angles  110  are acted on by at least one lever  104  which, during the downwards movement of the carriage  102 , is guided in a further connecting link  610  (see  FIG. 6   a ′ to  6   c ′). 
     The mode of operation of the embodiment according to  FIGS. 4 to 6  will now be described in more detail: starting from the position illustrated in  FIGS. 4 and 5   a  and  6   a ,  6   a ′, the drive (not shown here) initiates the downwards movement of the carriage  102  along the lift car door. The rollers attached to the carriage  102  follow the downwards movement of the carriage  102 , the rollers  108  travelling along the connecting link  109   a  of the guide unit  109 . 
     When travelling along the inclined portion  109   b  of the connecting link  109   a , the expander skate angles  110  are in this case extended so that the position shown in  FIGS. 5   b  and  6   b ,  6   b ′ is reached. 
     When the rollers  108  have reached the transition from the inclined portion  109   b  to the lower flat portion  109   c  of the connecting link  109   a , the expander skate angles  110  are fully extended in this embodiment as well ( FIG. 5   b ,  6   b ,  6   b ′). 
     During the further downwards movement of the carriage  102 , the rollers  108  move along the lower flat part  109   c  of the connecting link  109   a , the widening movement of the expander skate angles  110  relative to one another being initiated during this part of the downwards movement. 
     While the rollers  108  travel along the inclined portion  109   b  of the connecting links  109   a , the further connecting link  610 , provided in the upper portion of the carriage  102 , slides along a roller  620  configured on the lever  104 . In this respect, the purpose of the roller  620  is to guide the lever  104  in the connecting link  610 . The lever  104  is mounted rotatably on a first expander skate angle  110  by its first end (at  630 ). At its second end (in the view of  FIG. 6   a ′ to  6   c ′ at the left-hand end), the lever  104  is rotatably mounted on the further expander skate angle  110  (at  640 ). Advantageously, the lever  104  is able to pivot by means of a swiveling axis  650 . 
     In the position shown in  FIGS. 6   b  and  6   b ′, the upper end  610   a  of the connecting link  610  impacts on the roller  620  so that during the further downwards movement of the carriage  102 , the lever  104  thus pivots about the swiveling axis  650 . 
     The lever is mounted rotatably overall such that during this further downwards movement, the two expander skate angles  110  spread apart. 
     Reaching the lower end of the connecting links  109  by the rollers  108  coincides with the horizontal orientation of the lever  104 , shown in particular in  FIG. 6   c ′, at which the maximum widening of the expander skate angles  110  is also provided. 
     This horizontal arrangement of the lever  104  in this end state proves to be particularly favourable, since horizontal forces which are effective during a subsequent opening or closing of the lift car door and shaft door and which can act on the lever  104  are not transmitted onto the drive. 
     A comparison between the different connecting links  109  used in the two embodiments shows that the connecting links used in the first embodiment have a widening  109   d  in their lower portions which is not provided in the case of the connecting links  109   a  of the second embodiment. A yielding of the expander skate angles  110  in the event of a collision, for example with lift components provided on the shaft side, for instance in the case of a premature extension of the expander skate angles  110  due to a possible faulty operation is ensured in the second embodiment by means of a flexible mounting of the carriage  102  on a spring  680 . According to the second embodiment, it is possible to dispense with springs  105 , as provided in the first embodiment, as a result of the connecting links  109  which are configured as a restricted guidance. 
     The coupling between lift car door and shaft door which is provided in the position of  FIGS. 5   c ,  6   c ,  6   c ′, is released by correspondingly returning the components, as has already been described in detail with reference to the first embodiment. 
     It is also pointed out that, for safety reasons, a shaft door is usually locked by a locking mechanism. This measure means that it is impossible to open the shaft door during normal operation of the lift, if the lift car or lift car door is not positioned directly behind the shaft door. 
     A lock of this type can be coupled with the rollers  210 , and can be released in the manner illustrated above as a result of the expander skate angles  110  acting on the rollers  210 . Conversely this means that when the expander skate angles  110  have finished acting on the rollers  210 , the locking mechanism is again effective. A shaft door locking mechanism of this type is not described in detail here. 
     The threshold leading edge of the lift car (identified by reference numeral  150 ) and the threshold leading edge of the shaft door (identified by reference numeral  160 ) are shown in  FIGS. 2   a  to  2   c  and  5   a  to  5   c , to further illustrate the advantages associated with the present invention. The gap between these two edges  150 ,  160  is called the threshold spacing. 
     For example, it can be seen in  FIG. 2   a  that the expander skate angles  110  in the uncoupled state shown here partly project into the threshold spacing from the threshold leading edge  150  of the lift car door and are partly submerged in the lift car door. The same applies to the rollers  210  with respect to the threshold leading edge  160  of the shaft door. This partial submergence can maximise the spacing between catch means on the lift car side (here expander skate angles  110 ) and counter-catch means on the shaft side (here rollers  210 ). Since in conventional solutions, catch means and counter-catch means are in each case the components which project furthest into the threshold spacing, according to the invention it is possible to increase the effective threshold spacing compared to these conventional solutions. The term “effective threshold spacing” is understood here as meaning the minimum spacing between components provided on the shaft side and components provided on the lift car side. 
     The described mobility of the expander skate angles  110  advantageously makes it possible for the rollers  210  to be fully submerged in the shaft door, i.e. for the rollers  210  to be arranged fully on the right-hand side of the threshold leading edge  160  in the view of  FIG. 2   a . As an alternative or in addition, it is also possible to fully submerge the expander skate angles  110  in the lift car door while the lift car is moving in the lift shaft, i.e. positioned fully on the left-hand side of the threshold leading edge  150  in the view of  FIG. 2   a . These measures can further optimise, in particular can maximise, the effective spacing between expander skate angles  110  and rollers  210  while the lift car is moving in the lift shaft. In particular in the case of high-powered lift cars which move at a very high speed through the lift shaft, the partial submergence of expander skate angles  110  and/or of rollers  210  in the lift car door and respectively in the shaft door can effectively prevent rattling and wind noises which are produced when the spacing between the components on the lift car side and the components on the shaft side (here expander skate angles and rollers) is too small. 
     The device according to the invention can advantageously be freely positioned, for example in the case of glass doors, it can be positioned to the side of the respective door openings. It is also possible to position the device above or below the door opening. The device according to the invention is advantageously arranged at the centre of gravity or in the vicinity of the centre of gravity of the door, as is also known from the prior art. Particularly in the case of high-speed doors, this measure is in particular effective with regard to the prevention of rattling noises. 
     A further preferred embodiment of the invention will now be described with reference to  FIGS. 7 to 9 . 
     In addition to the coupling function described according to the embodiments illustrated above, this embodiment has a further function, namely a lift car door lock. 
     In this embodiment as well, the same or similar components are again provided with the same reference numerals, as used with respect to the embodiments above. 
     A lift car door lock ensures that a lift car door can (usually) only be opened when the lift car door is coupled with a shaft door (as described above), so that consequently, the lift car door and shaft door can only be opened and closed together. 
     The preferred embodiment, illustrated in the figures, of a lift car door lock firstly has on the lift car door  80  (again shown schematically) a hook bolt  701 , a connecting rod  702  and a locking lever  703 . These elements are attached on the lift car door side and cannot be extended with respect to a shaft door  90  which is also shown schematically here ( FIGS. 7   a  to  7   c ). 
     As extensible elements which, (together with the coupling mechanism described in detail above) can be extended in the direction of the shaft door  90 , the lift car door lock also has a driving (engaging) roller  704 , a driving (engaging) lever  705  and a further skate angle, identified in the following as a locking skate angle  706 , and also expediently a lower bearing lever  707 . 
     Provided on the shaft door side as an actuating means for this lift car door lock is a further roller  711  which is preferably configured vertically under one of the rollers  210  of the counter-catch means when the lift car door and shaft door are not coupled, as can be seen in particular in  FIGS. 8   a - 8   c.    
     The extensible elements of the lift car door lock (driving roller  104 , driving lever  105 , locking skate angle  106  and lower bearing lever  107 ) are connected to the extensible elements of the coupling mechanism such that they participate in the extending movement of the coupling mechanism, as can be seen in particular from  FIGS. 7   a  to  7   c . In this respect, the spacing between the catch means, in particular the expander skate angles  110  and the counter-catch means, i.e. the rollers  210 , is reduced until the expander skate angles  110  are positioned between the rollers  210  (analogously, for example to  FIG. 5   c ). The spacing between the extensible locking skate angle  106  and the roller  711  is reduced to the same extent, as can be seen in particular from  FIGS. 7   a ,  7   b.    
     As described above in detail, the contact between the expander skate angles  110  and the rollers  210  is produced during the subsequent widening movement of the expander skate angles  110  ( FIG. 7   c ,  8   c ,  9   c ), with the shaft door also being unlocked (by a mechanism which is not shown). 
     At the same time, the further roller  711  which is configured as leading with respect to the roller  210 , arranged vertically above said roller  711 , by a schematically illustrated lever mechanism  712 , presses against the locking skate angle  706  (see  FIG. 8   c ,  FIG. 7   c ). In so doing, the locking skate angle  706  transmits the resulting lifting force onto the driving roller  704  via the driving lever  705 , as can be seen in particular from  FIGS. 8   c  and  9   c.    
     The lifting force is further transmitted from the (extensible) driving roller  704  onto the locking lever  703  (not extensible). The locking lever  703  transmits the force onto the connecting rod  702  which actuates the hook bolt  701  ( FIG. 8   c ), thereby unlocking the lift car door. 
     To ensure this transmission of force, the non-extensible elements  101 ,  102  and  103  as well as the extensible elements  104 ,  105 ,  106 ,  107  of the lift car door lock are connected together or can be pivoted relative to one another by radial bearings. Some of these radial bearings are shown purely schematically and are identified by reference numeral  720 . 
     The lift car door lock is expediently configured such that, during a subsequent folding or uncoupling of the coupling device, it locks the lift car door again as a result of its own weight. 
     Analogously to the device, described above in detail, for coupling a lift car door with a shaft door of a lift, it proves to be particularly advantageous in the case of the described lift car door locking mechanism that due to its extensibility, a maximum spacing between components on the lift car door side and components on the shaft side can be realised. Thus, when a lift car door lock is provided, the effective threshold spacing, i.e. the spacing between components on the lift car door side and components on the shaft door side can also be maximised during the travel of the lift car. 
     A further advantage is the relatively simple adjustment of the components, since only one component on the lift car door side (locking skate angle  706 ) comes into contact with only one component on the shaft door side (roller  711 ) for the entire lift car door lock. 
     The illustrated lift car door lock is characterised in that it is integrated into the device for coupling a lift car door and a shaft door such that it also uses the movements functions thereof (extending, widening, folding, retracting) in order to realise its own functions (extending, unlocking, locking, retracting).