Abstract:
A device for monitoring the presence of steps and pallets of an escalator or moving walkway, such that missing steps or pallets are immediately detected, so that the drive will be stopped before the missing or defective part reaches the visible area of the escalator or moving walkway.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation of U.S. application Ser. No. 10/307,486 (Atty. Docket 31794-185242), filed on Dec. 2, 2002, whih is a continuation of International Application No. PCT/EP01/04750 filed Apr. 27, 2001, which claims priority of German Application No. DE 100 27 490.0 filed Jun. 2, 2000. The disclosures of the foregoing applications and the U.S. patents mentioned below are incoporated herein by reference in their entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a device for monitoring the presence of steps and pallets of an escalator or moving walkway, respectively.  
           [0003]    According to prevailing national and international safety regulations, escalators and moving walkways have to be equipped so that they may be automatically stopped as soon as problems arise at critical points.  
           [0004]    U.S. Pat. No. 5,526,256 to Sakata et al. teaches a control device for passenger transport installations. A first and second microcomputer are provided. The first microcomputer actively communicates, via actuators, with the safety elements, which are responsible for starting the movement of the passenger transport installation. Data from the actuators are used for starting the passenger transport installation. The second microcomputer monitors the behavior of the safety devices on the basis of incoming signals. In case of a breakdown of one of the microcomputers, the passenger transport installation is not stopped, but the second microcomputer overtakes the function of the first one. This arrangement results in significant risks during the continued operation of the passenger transport installation because the defect has not been eliminated but only transferred.  
           [0005]    In the operating state of a passenger transport installation, the step or pallet belt is a main source of problems. If a step or pallet actually breaks or falls out of the return strand, persons standing in the visible area of the escalator may be injured unless the escalator or moving walkway is immediately stopped.  
           [0006]    U.S. Pat. No. 5,361,887 to Zaharia et al. teaches a generic device for detecting the irregularity in step frequency. A proximity-sensing initiator, connected to a microprocessor, can detect if some pre-determined features are missing from an escalator step. In case of a missing characteristic feature, the drive of the passenger transport installation is stopped. If the microprocessor would break down, the passenger transport installation will no longer be functional, due to safety reasons. However, such a breakdown would result in the passenger transport installation being out of service for longer than is necessary.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to improve a device for monitoring the presence of steps or pallets of an escalator or moving walkway such that missing steps or pallets are immediately detected, and the escalator or moving walkway drive can be stopped, before the missing or defective part reaches the visible area of the escalator or moving walkway.  
           [0008]    It is a further object to provide a new evaluation capability-based criteria that meets current safety regulations and correspond to the norms, and which is still effective when the microprocessor breaks down.  
           [0009]    The above and other objects of the invention are achieved by a device for monitoring a presence of steps of an escalator or pallets of a pallet belt of a moving walkway having at least one initiator, which is operative as a function of proximity for producing signals representing a determination of a missing step of the escalator or a pallet of the pallet belt of the moving walkway. The device also includes an evaluation and control unit having at least two processors that are operatively coupled with the at least one initiator for stopping a drive of the escalator or moving walkway in response to the signals from the at least one initiator indicating a determination of a missing step or pallet by the at least one initiator. The at least two processors operate independently from each other, monitor each other, control the signals of the at least one initiator, and exchange with each other status messages about the respective operating state of the at least one initiator and their own operating state within predeterminable time intervals.  
           [0010]    According to another aspect of the invention, there is provided a method for monitoring a presence of steps of an escalator or pallets on a pallet belt of a moving walkway. The steps of the method include: sensing a presence of predeterminable, characteristic and recurring feature at a predeterminable place of the step or pallet belt in a contactless manner with at least one initiator that produces signals representing the feature or absence thereof; supplying the signals to an evaluation and control unit comprising at least two processors; processing and comparing the signals in the at least two processors of the evaluation and control unit; monitoring each processor with one of the other processors; and stopping a drive of the escalator or moving walkway when a feature is detected as absent.  
           [0011]    According to an exemplary embodiment of the invention, there is provided a device for monitoring the presence of steps of an escalator or pallets of a pallet belt of a moving walkway having at least one initiator arranged in proximity to a reversing area for each direction of the escalator or moving walkway. The initiator is operative as a function of proximity for producing signals representing a determination of a missing step of the escalator or a pallet of the pallet belt of the moving walkway. The device further includes an evaluation and control unit having at least two processors operatively coupled with the at least one initiator for stopping a drive of the escalator or moving walkway in response to the signals from the at least one initiator indicating a determination of a missing step or pallet by the at least one initiator. According to this embodiment, the at least two processors operate independently from each other and control the signals of the at least one initiator.  
           [0012]    Thus, the invention enables the contactless detection of missing steps or pallets on the basis of characteristic and always-recurrent features, i.e., features that are present at each step or pallet.  
           [0013]    The axel of each step or pallet can, for example, be used as the characteristic feature. The axel usually cooperates with a roller, which rolls on a guide and is thus always arranged on the same level.  
           [0014]    Preferably, the initiator(s) is/are positioned in the region of the housing by means of a respectively associated support and is/are directed towards the characteristic feature, for example the bolt of the step or pallet rolls, which are provided outside the drive branch.  
           [0015]    For preventing the missing or defective component (step or pallet) from reaching the visible area of the escalator or moving walkway, the initiator(s) is/are preferably provided in the return strand in proximity to the reversing area of the step or pallet belt, so that upon detecting a missing step or pallet, the drive of the escalator or moving walkway can be immediately stopped via the evaluation and control unit.  
           [0016]    Usually, it is sufficient to provide the device with a single initiator for each running direction of the escalator or moving walkway. However, if the effective regulations of individual countries prescribe more, i.e. stricter criteria, two initiators placed side by side are used, so that a redundant safety is given.  
           [0017]    According to another aspect of the invention, processors, which operate independently from each other and control the signal(s) of the initiator(s), are provided in the region of the evaluation and control unit, which processors preferably monitor each other. The processors are coupled with safety contacts for immediately stopping the drive of the escalator or moving walkway. The processors exchange status messages with each other about the respective operating state of the initiator(s), on the one hand, and their own operating state, on the other hand, within pre-determinable time intervals.  
           [0018]    If an initiator breaks down, or if the the processors, which monitor each other, are not in agreement, the drive of the escalator or moving walkway is automatically stopped.  
           [0019]    The velocity profiles (normal speed, creep speed) relating to the escalator or moving walkway are stored within the evaluation and control unit, so that the throughput times, which change due to changing velocities, at the initiator(s) can be recognized without any problems by the evaluation and control unit and associated with the respective operating state. For adaptation to different speeds, so-called self-learning programs, such as adaptive speed recognition, autotuning and teach-in methods, can be used.  
           [0020]    For maintenance of the escalator or moving walkway, a manual drive of the step or pallet belt via special control elements is provided (driving mode for inspection), so that the safety device can be switched off for this purpose.  
           [0021]    The objects of the invention are achieved by means of exemplary embodiments shown in the drawings and described as follows. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a schematic diagram showing a partial side view of an escalator with a safety device according to the invention;  
         [0023]    [0023]FIG. 2 is a schematic, including a partial block diagram, of the safety device; and  
         [0024]    [0024]FIG. 3 is a partial representation of the evaluation and control unit in combination with the initiators. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    [0025]FIG. 1 shows an escalator  1  with two reversing areas  2 , 3  for the steps  4  of the step belt  5 . In the return strand, i.e., in the area of escalator  1  not normally visible, supports  6 , 6 ′ are provided in proximity to the reversing areas  2 , 3 , which supports respectively receive initiator  7 , 7 ′, which is graphically depicted.  
         [0026]    [0026]FIG. 2 shows a partial view of support  6 , a step  4 , a driving element  8  coupled to step  4 , as well as a step roll  9 . Furthermore, FIG. 2 shows the support  6 , which supports the initiator  7  according to the invention in this diagram, which initiator cooperates with an evaluation and control unit  11  (FIG. 3) represented in FIG. 2 via a line  10 . The support  6  is fixed in the region of housing  12 . Step roll  9 , which rolls on a guide path  13 , always has the same distance to each step  4 , so that it is possible without any problems to direct the initiator  7  towards the bolt (not shown) of step roll  9 , so that the same represents a characteristic, always recurring feature of each step  4 .  
         [0027]    [0027]FIG. 3 is a schematic diagram showing the evaluation and control unit  11 , which is in active relation with two initiators  7 , 7 ′, which are positioned with pre-determinable distance to each other. Furthermore, FIG. 3 shows a pallet belt  5 ′ including pallets  4 ′ of a graphically depicted moving walkway. Each pallet  4 ′ is provided with a pallet roller  9 ′, which is connected to the respective pallet  4 ′ via a bolt  15 . The initiators  7 , 7 ′ are again provided in proximity to reversing area (not shown) of the pallets  4 ′ and directed towards the level of the pallet bolt  15 , which represents a characteristic and always recurring feature.  
         [0028]    The evaluation and control unit  11  includes two microprocessors  16 , 17 , which are connected to the initiators  7 , 7 ′. The microprocessors  16 , 17  are interconnected via data lines  18 , so that a mutual monitoring is ensured. Thus, the microprocessors  16 , 17  not only control themselves with respect to locally occurring disturbances, but also check whether the initiator impulses, which are supplied to the respectively other microprocessor  16 , 17 , are within a set tolerance range. The reference numerals  19 , 20  indicate the power supply of the so-called safety chain and the power supply of the evaluation and control unit  11  itself, respectively.  
         [0029]    In case of a disturbance in the range of one of the initiators  7 , 7 ′, the contact  21  or  22  of graphically depicted safety relays is actuated by microprocessor  16  or  17 , which leads to the immediate stopping of the graphically depicted drive of the moving walkway. Outside the evaluation and control unit  11 , other contacts  23 , 24 , 25  of other safety elements  26 , 27 , 28 , e.g. emergency shutdown contacts or the like, are provided.  
         [0030]    If one of the initiators  7 , 7 ′ breaks down or if the start signals exchanged between the microprocessors  16 , 17  do not coincide, the drive of the moving walkway will automatically be stopped. If one of the initiators  7 , 7 ′ fails to detect the characteristic feature, namely bolt  9 ′ of a pallet  4 ′, within a predetermined time interval, this failed detection is transmitted to the respective microprocessor  16 , 17  via the signal lines  29 , 30 , whereby the drive can be stopped.  
         [0031]    In the normal case (when the escalator is running), there is a sequence of impulses (signals), wherein the evaluation unit  11  also monitors defects of the initiators  7 , 7 ′ or the lines  29 , 30  themselves. The signals are comprised between 0 and 1. If one signal becomes a constant 0 or 1, it can be assumed that there is a defect in the region of an initiator  7 , 7 ′ or a line  29 , 30 . Consequently, the drive can be stopped.  
         [0032]    While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should instead be defined only in accordance with the following claims and their equivalents.