Abstract:
An electromechanical monitoring device for detecting undesired departure of an elevator cage from standstill is disclosed. The electromechanical monitoring device includes a co-running wheel which when required is pressed against a guide track of the elevator cage, possibly against a running diameter of the speed limiter. A sensor detects rotation of the co-running wheel and actuates a braking device if a rotational angle of the co-running wheel exceeds a predetermined value. This electromechanical monitoring device can be suitable for attachment to or installation in a speed limiter and can be suitable for retrofitting to elevator installations.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to European Patent Application No. 10195788.4, filed Dec. 17, 2010, which is incorporated herein by reference. 
       FIELD 
       [0002]    The disclosure relates to detecting departure of an elevator cage from standstill. 
       BACKGROUND 
       [0003]    An elevator installation is installed in a building. It substantially comprises an elevator cage which is connected by way of support means with a counterweight or with a second elevator cage. By means of a drive, which selectably acts on the support means or directly on the elevator cage or the counterweight, the elevator cage is moved along substantially vertical guide rails. The elevator installation is used for transporting persons and goods within the building over single or multiple stories. The elevator installation includes devices in order to help ensure safety of the elevator installation. A device of that kind protects, for example in the case of stopping at a story of the building, the elevator cage from unintended drifting away. For that purpose use is made of, for example, braking devices which, when required, can brake the elevator cage. 
         [0004]    A device of that kind is known from WO 2005/066058. The device consists of a clamping device which in the case of standstill of the elevator cage clamps a moved part, a movement sensor system which detects movement of the clamping device and a control device which evaluates the movement and actuates a safety device if required. 
       SUMMARY 
       [0005]    At least some of the disclosed embodiments provide an alternative monitoring device for detecting unintended departure of an elevator cage from standstill, which can be simple to install and which can also be suitable for retrofitting in an elevator installation if required. 
         [0006]    According to one variant of embodiment of an electromechanical monitoring device for detecting unintended departure of an elevator cage from standstill the electromechanical monitoring device includes a co-running wheel which when required is pressed against a guide track of the elevator cage. A requirement of that kind is, for example, a stop at a story. This can be detected in that a drive of the elevator installation stops, and an associated first braking device or a drive brake is actuated or an access door to the cage is opened. During normal travel of an elevator cage the electromechanical monitoring device is in a normal setting, i.e. the co-running wheel is spaced from the guide track and thus does not contact the guide track. If required, the electromechanical monitoring device is brought into a readiness setting, i.e. the co-running wheel is pressed against the guide track, whereby in the case of movement of the elevator cage it is rotated in correspondence with a movement direction. 
         [0007]    The monitoring device further includes a sensor which detects rotation of the co-running wheel through a predetermined rotational angle. If the sensor detects exceeding of the predetermined rotational angle, a braking device, possibly a second braking device, is actuated or it initiates another action which fixes or brakes the elevator cage. The electromechanical monitoring device is then in its trigger setting. The second braking device can, for example, be a cage brake or a safety brake device, which is arranged directly on the elevator cage and which is in a position of fixing the elevator cage in co-operation with a wall of the elevator shaft or a guide rail of the elevator cage, etc. 
         [0008]    The use of the co-running wheel, which if required is pressed against the guide track of the elevator cage, can be advantageous, since coming into question as the guide track is any track or surface which runs continuously over the travel path of the elevator cage or represents the travel path of the elevator cage. The co-running wheel can be of simple design and can be correspondingly advantageous to procure. 
         [0009]    A rotational angle transmitter can be used as sensor, wherein a rotational angle of the co-running wheel is detected. In this regard, the braking device is triggered in the case of exceeding of a preset rotational angle. If required, two or more rotational angles can also be preset. In that case, in the case of exceeding of a first rotational angle at the co-running wheel the braking device is actuated and in the case of exceeding of a further value, for example, a prong could be moved out which firmly engages in the region of the elevator door or of rail fastenings, etc. 
         [0010]    An elevator installation equipped with a monitoring system of that kind can be particularly reliable and advantageous with respect to safeguarding against drifting of the elevator cage away from a stopping point and can be suitable for being installed or retrofitted in an existing elevator installation. If needed, an existing braking device can in that case be activated. Insofar as an appropriately activatable braking device is not present in the elevator, an electromechanical actuation such as known from, for example, EP 0543154 can, however, be incorporated in an existing braking device or obviously also a new, remotely actuable brake can be installed. 
         [0011]    A corresponding retrofitting device of the monitoring system possibly includes a support which contains the required mounting positions for movable parts such as a rocker for mounting the co-running wheel, etc. A retrofitting device of that kind can be employed at and fastened to a guide track of the elevator cage in simple manner. Further mechanical adaptations are not necessarily required, since entrainment of the co-running wheel takes place solely by friction couple through pressing of the wheel against the guide track. Moreover, the retrofitting device possibly also includes a corresponding electronics box which contains the required circuits for activation of the monitoring device as well as energy supply units with store. 
         [0012]    In another embodiment or development the co-running wheel drives a cam disc. The cam disc can in that case be directly combined with the co-running wheel. The sensor, which in this embodiment can be an electromechanical switch, is now actuated in simple manner by a cam of the cam disc on rotation of the co-running wheel or of the associated cam disc. This can be an economic construction, since there is no need for an expensive electronic evaluating system. As soon as the co-running wheel is pressed against the guide track of the elevator cage and a movement of the elevator cage takes place the co-running wheel together with the cam is rotated. As soon as the cam reaches the electromechanical switch this is switched and a braking device controlled by this switch is actuated. 
         [0013]    In another embodiment or development the co-running wheel, if need be together with the cam disc, is automatically moved into a neutral setting or zero position as soon as the co-running wheel is spaced from the guide track. This can take place, for example, by way of a spring device or, possibly, the co-running wheel or the cam disc connected therewith is so constructed that a gravitational center of mass constrainedly rotates the cam disc or the cam back into the neutral setting or zero position. It can be advantageous in this connection if the preset rotational angle corresponds with half a revolution of the co-running wheel. A single electromechanical switch can thus recognize drifting away of the elevator cage in both directions of travel. This embodiment can enable an economic and reliable monitoring device, since, in particular, the function thereof can also be simple to see and understand. 
         [0014]    In another embodiment or development the electromechanical switch is a commercially available detenting or bistable switch. This means that the switch after actuation remains in the switched position until it is reset back to the normal or working position either manually or by an appropriate remote resetting device. Possibly, this switch is so constructed that a power circuit for activation of the braking device is closed in the normal or working position and is correspondingly interrupted in the actuated or switched position. A level of safety can thereby be achieved, since interruption in the activation always leads to braking. 
         [0015]    In another embodiment or development the co-running wheel is pressed against the guide track of the elevator cage by means of a pressing spring and is kept at a spacing from the guide track by means of an electromagnet. Possibly, the electromagnet is designed in such a manner that it can draw away the co-running wheel against a spring force of the pressing spring. Thus, in the case of energy failure the monitoring device is automatically moved into the readiness setting or slipping of the elevator cage is monitored and at the same time by virtue of the pressing spring different forms of an attachment can be realized. Moreover, this monitoring system is insensitive to vibrations. 
         [0016]    The drive control of the electromagnet can be equipped with an energy store, for example a battery, in order in the case of power failure in the building to keep the co-running wheel at a spacing from the guide track at least during running-on of the elevator cage until standstill. 
         [0017]    Alternatively or additionally the co-running wheel is pressed by means of weight mass against the guide track of the elevator cage and it is kept at a spacing from the guide track by means of an electromagnet. Possibly, in that case the electromagnet is designed in such a manner that it can draw the co-running wheel away from the guide track against a weight mass. This can provide an economic and reliable construction, since the weight force is available on a worldwide basis. This system also otherwise corresponds with the embodiment such as explained in conjunction with the pressing spring, wherein in the case of installation in an elevator installation the installed position has to take into consideration the course of the weight force. 
         [0018]    If required, the co-running wheel or the guide track against which the co-running wheel is pressed can be structured, corrugated, roughened or milled so as to help ensure reliable driving of the co-running wheel. It can also be made from or coated with a material with a high coefficient of friction such as, for example, polyurethane. 
         [0019]    In another embodiment or development the guide track of the elevator cage corresponds with a circumference of a speed limiter and the speed limiter is connected or connectible with a limiter cable for the elevator cage. This cable rotates the speed limiter in correspondence with a movement of the elevator cage, whereby the movement of the circumference of the speed limiter directly represents the guide track of the elevator cage. The electromechanical monitoring device is accordingly arranged at the speed limiter or directly installed at the speed limiter, wherein the co-running wheel is if required pressed against the circumference of the speed limiter. 
         [0020]    In this embodiment the monitoring device can be installed in or attached to an existing elevator installation in particularly simple manner, since the equipment can be mounted in stationary position in the building and associated electrical wiring can be led to an elevator control. In addition, a substitute speed limiter can now be directly provided for an existing elevator installation. Thus, for the purpose of retrofitting an elevator installation an existing speed limiter without a monitoring device can be simply be exchanged for the new speed limiter with a monitoring device. 
         [0021]    Combinations of the illustrated embodiments enable individual solutions appropriate to requirement. The monitoring device can also be installed at any other disc which is connected with the elevator cage and rotates in correspondence with movement of the elevator cage. Such a disc can be, for example, a drive pulley, a deflecting or diverting roller, a support roller or also a guide roller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The disclosed technologies are explained using exemplary embodiments and using the figures, in which: 
           [0023]      FIG. 1  shows a schematic view of an elevator installation in side view, with a monitoring device attached to the elevator cage, 
           [0024]      FIG. 2  shows a schematic view of an elevator installation in side view, with a monitoring device attached to a speed limiter, 
           [0025]      FIG. 3  shows an electromechanical device in normal setting, 
           [0026]      FIG. 4  shows the electromechanical monitoring device of  FIG. 3  in readiness setting, 
           [0027]      FIG. 5  shows the electromechanical monitoring device of  FIG. 3  in trigger setting, 
           [0028]      FIG. 6  shows the electromechanical monitoring device of  FIG. 3  in conjunction with a guide track of a speed limiter and 
           [0029]      FIG. 7  shows an electromechanical monitoring device attached to a speed limiter. 
       
    
    
       [0030]    The same reference numerals are used in the figures for equivalent parts over all figures. 
       DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows an elevator installation in overall view. The elevator installation  1  is installed in a building, possibly in an elevator shaft  2 . It substantially consists of an elevator cage  3 , which is connected by way of support means  5  with a counterweight  4  or alternatively also with a second elevator cage (not illustrated). The cage  3  and correspondingly also the counterweight  4  are moved along substantially vertical guide rails  8  by means of a drive  6  which possibly acts on the support means  5 . The elevator installation  1  is used for transporting persons and goods within the building over individual or several stories. 
         [0032]    The drive  6  is connected with an elevator control  7  which controls and regulates the drive  7  and thus the elevator installation  1 . The elevator control  7  is, in the example, also connected by way of a suspension cable  32  with the elevator cage  3  in order to exchange requisite signals. 
         [0033]    The elevator installation  1  includes braking devices  9  in order to fix the elevator cage when required and to ensure safety of the elevator installation. In the example a first braking device  10  is arranged in the region of the drive  6 . This first braking device  10 , for example, fixes the elevator installation or the elevator cage  3  in the case of a stop at a story. This first braking device  10  is usually a component of the drive  6  and is activated by the elevator control  7 . This first braking device  10  can also be arranged separately from the drive  6 , for example on the elevator cage or the counterweight or at a deflecting roller. The elevator installation  1  includes a further, second braking device  11  which is arranged directly on the elevator cage  3  and which can act directly on the guide rail  8  for the purpose of braking the elevator cage  3 . This second braking device  11  is, in the example, a safety brake device which is activated by means of an electronic limiter by way of a safety device  27 . 
         [0034]    The elevator installation  1  further includes an electromechanical monitoring device  12  which is arranged at the elevator cage  3  and which in co-operation with a guide track  14  defined by the guide rails  8  of the elevator cage  3  can detect an unanticipated slipping away or drifting away of the elevator cage  3  and can actuate the second braking device  11  by way of the safety device  27 . Energy stores  28  which may be required can be arranged in the safety device. This energy store can ensure, in the case of failure of the energy mains, at least functioning of the electromechanical monitoring device  12  until the elevator installation is at standstill. Details of the electromechanical monitoring device  12 , such as is used in the elevator installation according to  FIG. 1 , are explained in  FIGS. 3 to 5 . 
         [0035]      FIG. 2  shows another embodiment of an electromechanical monitoring device  12  in an elevator installation. The elevator installation in basic concept is constructed as explained in  FIG. 1 . However, this elevator installation  1  includes a second braking device  11  which can essentially be a known conventional safety brake device. This safety brake device is, when required, actuated by a speed limiter  24 . The speed limiter  24  is connected with the safety brake device by way of a limiter cable  26 . The limiter cable  26  is thus moved by the elevator cage  3 , at which the safety brake device is arranged, in company therewith and the speed limiter  24  is correspondingly moved by the limiter cable  26 . As soon as the speed limiter  24  detects an excessive speed, the speed limiter  24  blocks the limiter cable  26  and the now braked limiter cable  26  actuates—usually by way of an appropriate lever mechanism (not illustrated)—the safety brake device or the second braking device  11 . 
         [0036]    In the embodiment according to  FIG. 2  the electromechanical monitoring device  12  is arranged at this speed limiter  24 . In co-operation with a guide track  14 , which is defined by a circumference of the speed limiter  24 , the electromechanical monitoring device  12  can detect an unanticipated slipping or drifting away of the elevator cage  3  and it can actuate the second braking device  11  by way of an auxiliary triggering means  34 . In the example, the auxiliary triggering means is controlled by way of the elevator control  7  and the suspension cable  32  by the electromechanical monitoring device  12 . The auxiliary triggering means  34  is, for example, a clamp which when required engages the guide rail  8  and actuates the safety brake device. An auxiliary coupling of that kind is known from, for example, the publication EP 0543154. Alternatively, a second brake  11  which is additional to the safety brake device can also be mounted on the elevator cage and then is actuated, for example, by the electromechanical monitoring device  12  merely to prevent drifting away. Details of the electromechanical monitoring device  12  such as is now used in the elevator installation according to  FIG. 2  are explained in  FIGS. 6 and 7  in conjunction with  FIGS. 3 to 5 . 
         [0037]    A construction and the function of an electromechanical monitoring device  12  such as can be used in the elevator installation according to  FIG. 1  or analogously also in  FIG. 2  are explained in  FIGS. 3 to 5 . The electromechanical monitoring device  12  includes a support  29  which can be fastened to a part of the elevator installation, for example to the elevator cage, the speed limiter or a frame of the drive. A rocker  30  is mounted on the support  29  to be pivotable about a pivot axis  21 . A co-running wheel  13  is rotatably mounted in the rocker  30  and a cam disc  17  with a cam  18  co-runs on the rotational axle of the co-running wheel  13 . 
         [0038]    The weight component of the cam  18  in that case rotates, due to the weight force, the cam disc  17  in the normal position as long as no external forces are present. The rocker  30  is moved by means of an electromagnet  22  between a normal setting as illustrated in  FIG. 3  and a readiness setting as illustrated in  FIG. 4 . In the example, a spring  20  urges the rocker  30  together with the co-running wheel  13  into the readiness setting (see  FIG. 4 ) and the electromagnet  22  draws the rocker  30  back into the normal setting against the spring force of the spring  20 . 
         [0039]    The electromechanical monitoring device  12  or the support  29  is so arranged with respect to the guide track  14  that in the normal setting the co-running wheel  13  is at a spacing from the guide track  14 , thus free of contact. In the readiness setting the co-running wheel  13  is pressed against the guide track  14 . Activation of the electromagnet  22  is carried out, for example, by way of the safety device  27  or directly by way of the elevator control  7 . Thus, for example, as soon as a door of the elevator cage  3  is opened by a certain amount the electromagnet  22  is switched by way of a corresponding switch to be free of current and the co-running wheel  13  is pressed against the guide track  14  or the electromagnet is switched to be free of current as soon as the first braking device  10  receives a command for closing. 
         [0040]    In one embodiment the safety device  27  for activation of the electromechanical monitoring device  12  is so constructed that it takes into consideration a combination of the signals of the first braking device  10  and the closed or opened state of the door of the elevator cage  3 . Alternatively, instead of or in addition to the closed or opened state of the door of the elevator cage  3  use can also be made of story information, for example a story switch which is switched when the elevator cage  3  is located in the region of a story or a floor. This can be useful, for example, in old elevator installations where in part use is still made of elevator cages without a cage door. The response behavior of the electromechanical monitoring device  12  can thus be matched to specific characteristics of the elevator installation. 
         [0041]    If the elevator cage  3  now remains correctly at standstill, the co-running wheel  13  with the cam  18  remains in the readiness setting illustrated in  FIG. 4 . 
         [0042]    If, however, the elevator cage  3  unintentionally moves out of standstill as illustrated in  FIG. 5  by the movement arrow s, the cam disc  17  together with the cam  18  is rotated through a rotational angle  16 . The setting of this rotation or the rotational angle  16  is detected by a sensor  15 , constructed as an electromechanical switch  19  in the example. If the switch  15  is now actuated by the cam  19 , the electromechanical monitoring device  12  is disposed in the trigger setting and the second braking device is thereby actuated (see  FIG. 1  or  FIG. 2 ). 
         [0043]    As long as the switch  19  is not actuated, the electromagnet  22  can draw the rocker  30  back again at any time and the cam  18 , by virtue of its weight, again returns to the normal position. However, as soon as the switch  19  is actuated the intervention of an informed person is usually required in order to reset the device. In this embodiment a response sensitivity of the device is determined by way of the geometry of the co-running wheel. For example, a diameter of the co-running wheel is so selected that a response delay in correspondence with a travel deviation s of approximately 30 to 100 mm (millimeters) arises. In an exemplifying embodiment a diameter of the co-running wheel is approximately 50 mm. A travel deviation s of approximately 75 mm is thus recognized. Typical small movements of the elevator cage at standstill can thus be picked up. These small movements arise, for example, due to stretchings of the support means during loading and unloading processes. 
         [0044]    The same electromechanical monitoring device  12  as explained with reference to  FIGS. 3 to 5  can also be arranged at a curved guide track  14 . This is illustrated in  FIG. 6 , by way of the trigger setting, analogously to  FIG. 5 . The electromagnet  22  has freed the rocker  30  and the spring  20  presses the co-running wheel  13  against the guide track  14 . In the example, this guide track  14  is a running diameter  25  of the speed limiter  24 . The guide track  14  can alternatively also be defined by a deflecting roller or a guide roller. 
         [0045]    In  FIG. 7  the electromechanical monitoring device  12  is installed in a speed limiter  24 . The illustration shows the electromechanical monitoring device  12  in the readiness setting in correspondence with  FIG. 4 . The speed limiter  24  is driven by means of a limiter cable  26  and connected with the elevator cage. The rocker  30  is arranged at the speed limiter  24  to be pivotable about the pivot axis  21 . The co-running wheel  13  together with the cam disc  17  and the cam  18  is rotatably mounted on the rocker  30 . The electromagnet  22 , which in the example according to  FIG. 7  is fastened to the speed limiter  24  by way of an auxiliary bracket  29 . 1 , is in the illustrated readiness setting switched to be free of current and the intrinsic weight of the rocker  30  urges the co-running wheel  13  against a running diameter  25  of the speed limiter  24 . The running diameter  25  thus forms the guide track  14  for the electromechanical monitoring device  12 . 
         [0046]    If the elevator cage was now moved away from standstill, the co-running wheel  13  would rotate the cam  18  and after approximately half a revolution of the co-running wheel  13  the cam  18  would actuate the safety switch  19  or the sensor  15 , whereby, as already explained several times, a braking device would be brought into action. 
         [0047]    On the other hand, in the example according to  FIG. 7 , the electromagnet  22  in switched-on state can urge the rocker  30  together with the co-running wheel  13  away from the running diameter  25 , whereby the electromechanical monitoring device  12  can be brought into its normal setting. 
         [0048]    The electrical parts of the electromechanical monitoring device  12  are connectible with the elevator control  7  or the safety device  27  by way of an electrical connecting cable  33 . 
         [0049]    With knowledge of the present disclosure one can change the set shapes and arrangements as desired. For example, the cam disc  17  can be formed with a plurality of cams or several sensors  15  or switches  19  can be arranged over the rotational angle  16  of the cam disc. One can design constructional shapes and select feasible materials. Thus, one can load sub-regions of the rocker so as to obtain sufficient pressing forces. 
         [0050]    Having illustrated and described the principles of the disclosed technologies, it will be apparent to those skilled in the art that the disclosed embodiments can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of the disclosed technologies can be applied, it should be recognized that the illustrated embodiments are only examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims and their equivalents. I therefore claim as my invention all that comes within the scope and spirit of these claims.