Abstract:
The present invention provides a control system designed for use in either new or existing escalators or moving walkways. The control system is comprised of a main controller and a variable frequency drive. The main controller is attached to the variable frequency drive which controls the speed of the motor based upon various environmental changes, such as passenger load and safety conditions. The control system of the present invention utilizes motions sensors, time relay switches, proximity switches and other electromechanical detectors as intelligence to detect faults and to control and vary the speed of the motor through the variable frequency drive.

Description:
[0001]    This application claims priority of U.S. provisional application Serial No. 60/295,362 filed on May 31, 2001, which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to a system for controlling and monitoring the motion, operation, performance, condition and safety of a moving walkway or escalator. In particular, the control system is designed to be utilized with either existing or new escalators and moving walkways.  
           [0004]    2. Description of the Related Art  
           [0005]    Currently, sophisticated escalator or moving walkway control systems are microprocessor based control systems that are built by original equipment manufacturers (“OEMs”). Typically, these microprocessor based control systems are highly proprietary to each OEM. As a result, the microprocessor based systems are not generally designed to be retrofitted to existing systems. Thus, existing escalators must generally be completely overhauled or replaced for the installation of a microprocessor based control system. Furthermore, all purchases of an OEM control system generally includes a service contract since no other company besides the OEM is typically able to maintain the highly proprietary system, including the purchaser.  
           [0006]    To date, systems which are easily maintained have not been as sophisticated as the microprocessor based control systems. Although these microprocessor based control systems are often undesirable from the service and maintenance standpoint, microprocessor based systems provide added functionality over the previous systems.  
           [0007]    A need therefore exists for a sophisticated escalator control system that does not utilize a highly proprietary microprocessor based control system, but utilizes equipment that is compact and that is easy to install, maintain, repair, replace and upgrade and that can be retrofitted to existing systems, all without the assistance of the OEM.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a control system designed for use in either new or existing escalators or moving walkways. The control system is comprised of two major components: a main controller and a variable frequency drive. The main controller is attached to the variable frequency drive which controls the speed of the motor based upon various environmental changes, such as passenger load and safety conditions. Unlike the microprocessor based systems, the control system of the present invention utilizes motions sensors, time relay switches, proximity switches and other electromechanical detectors as intelligence to detect faults and to control the application and timing of the brake and to control and vary the speed of the motor via the variable frequency drive.  
           [0009]    When used in connection with existing systems, the main controller may utilize existing field components, such as field wiring, safety devices, emergency stops and the lighting system, as originally installed. Major and minor faults are monitored by emergency stop relays. Escalator speed signals are monitored by individual speed relays. Circuitry for starting and stopping the escalator by the means of push buttons are located, at minimum, at the upper and lower entrances and/or exits to the escalator. All circuits are designed in a fail-safe mode. Thus, the absence of power or a signal, due to the detection of a fault, among other things, will cause the escalator to stop.  
           [0010]    The motor for the escalator and moving walkway is controlled by a variable frequency controller. The controller receives operating parameters (run signal) from the main controller. Starting and stopping characteristics are programmed into the main controller, which allow for a pre-programmed acceleration and deceleration rate, along with a speed rate. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    A more complete appreciation of the invention and many of the advantages thereof will be readily obtained as the same becomes better understood by references to the detailed description when considered in connection with the accompanying drawings, wherein:  
         [0012]    [0012]FIG. 1 is a block diagram of one embodiment of the escalator control system of the present invention;  
         [0013]    [0013]FIG. 2 is a diagram illustrating the electrical schematics of the main controller and variable frequency drive;  
         [0014]    [0014]FIG. 3 is a diagram illustrating the electrical schematics of the main controller and the lighting system;  
         [0015]    [0015]FIG. 4 is a circuit diagram illustrating the motion control system, including proximity sensors for detecting the speed of the handrail and escalator stairs;  
         [0016]    [0016]FIG. 5 is a diagram illustrating the electrical schematics of the stop button, the main controller and the horn;  
         [0017]    [0017]FIG. 6 is a partial hardware electrical schematic of the main controller;  
         [0018]    [0018]FIG. 7 is a continuation from FIG. 6 of the hardware electrical schematic of the main controller;  
         [0019]    [0019]FIG. 8 is a continuation from FIG. 7 of the hardware electrical schematic of the main controller;  
         [0020]    [0020]FIG. 9 is a partial diagram of the interlocks to the upper fault box;  
         [0021]    [0021]FIG. 10 is a continuation from FIG. 9 of the diagram of the interlocks to the upper fault box;  
         [0022]    [0022]FIG. 11 is a partial diagram of the interlocks to the lower fault box;  
         [0023]    [0023]FIG. 12 is a continuation from FIG. 11 of the diagram of the interlocks to the lower fault box; and  
         [0024]    [0024]FIG. 13 is a block diagram of the present invention illustrating its use in connection with an Ethernet or Internet type monitoring system.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Turning now to the detailed drawings, FIG. 1 is a block diagram of one embodiment of the escalator control system  10  of the present invention. In this embodiment, the escalator control system  10  is comprised of a main controller  12 , an upper fault box  20 , a lower fault box  22 , a variable frequency drive  14 , a motor  16 , a brake  18 , a lighting system  26  and a motion control system  24  comprised of, among other things, several proximity switches  32 .  
         [0026]    As seen in FIG. 1, the main controller  12  is powered via 480 V/AC through a main line disconnect  30 . The main controller  12  connects directly to the variable frequency drive  14 , the upper fault box  20  and the lighting system  24 , as well as to a motion control system  24  for monitoring the movement and speed of the handrails and escalator stairs. The variable frequency drive  14  is used to control the speed of the motor  16  and, as shown in FIG. 1, may be connected to the upper fault box  20 , which is then connected directly to the motor  16 . Alternatively, the variable frequency drive  14  may be connected directly to the motor  16 .  
         [0027]    Further, circuitry extends from the lower and upper fault boxes  20  and  22  for push buttons and switches (not shown) used to stop the escalator in the event of an emergency or to change the direction of the escalator. These buttons and switches are generally positioned near the handrails of the escalator. One set of buttons and switches extend from the upper fault box  20  and are connected to the upper hand rail, while another identical set of buttons and switches extend from the lower fault box  22  and are connected to the lower hand rail of the escalator.  
         [0028]    While FIG. 1 illustrates the escalator control system  10  having a upper fault box  20  and a lower fault box  22 , the upper and lower fault boxes  20  and  22  are not essential to the escalator control system  10 . In its simplest form, the escalator control system  10  may only include the main controller  12  connected directly to a variable frequency drive  14 , a motor  16 , a brake  18  and a lighting system. The main controller would also include a motion detecting system  24  and a fault detecting system that communicates directly with the main controller  12  rather than via a junction box, i.e., upper and lower fault boxes  20  and  22 . Thus, the intermediate upper and lower fault boxes  20  and  22  may be eliminated. By removing the upper and lower fault boxes  20  and  22 , certain additional functionalities may, however, be lost.  
         [0029]    [0029]FIG. 2 is a diagram illustrating the electrical schematics of the main controller  12  and the variable frequency drive  14 . In this diagram, as well as in the diagrams contained in FIGS.  1 - 12 , all solid lines represent equipment and/or circuitry located in the main controller  12  and all dashed lines, both evenly and unevenly spaced, represent equipment or devices which are field mounted outside of the main controller  12 .  
         [0030]    As illustrated, 480 V/AC is supplied to the main controller  12 , which then powers the variable frequency drive  14  via a three-phase power input  28 . Once powered, the variable frequency drive  14  is able to output alternating current to the motor  16 . In the illustrated embodiment, current is output to the motor  16  via three power output wires  29 .  
         [0031]    Also illustrated on FIG. 2 is one embodiment of a start/stop control circuit  38 , which controls the direction of the escalator stairs and starts and stops the escalator via maintained contacts  40 ,  42  and  44 . The start/stop control circuit  38  illustrated in this embodiment is a three-wire start/stop control scheme  46  using one maintained contact  40  to run the escalator up, another maintained contact  42  to run the escalator down, as well as start and stop contacts  44 . While this diagram illustrates a three-wire start/stop control scheme  46 , other control schemes, such as traditional and alternate two-wire control schemes, may also be utilized depending upon the needs of the system  10 .  
         [0032]    Terminals  50  are also included in the variable frequency drive  12  for determining whether the variable frequency drive is faulted or not faulted and running or not running via maintained contacts  52 ,  54 ,  56  and  58 , respectively, and for communicating this information the main controller  12 , as illustrated further in FIGS. 6, 7 and  8  and as described below.  
         [0033]    [0033]FIG. 3 is a circuit diagram illustrating the connection between the main controller  12  and the lighting system  26 . When the escalator is running, the circuit to the lighting system  26  is closed via maintained contacts  62 , sending 480 V/AC to the lighting system  26 , which is then converted to 24 V/AC via converters  60  to power the upper demarcation lights  64  and lower demarcation lights  66 .  
         [0034]    [0034]FIG. 4 illustrates the motion control system  24  of the present invention. As illustrated in FIG. 4, the 480 V/AC is converted via a converter  60  into both 24 V/AC and 120 V/AC. The 120 V/AC circuit is shown in FIG. 4, whereas the 24 V/DC circuit is illustrated in FIG. 5. Illustrated in this diagram is a relay loop  70  containing a brake time relay  72 , which communicates with a brake solenoid  90 . The time relay  72  and the break solenoid  90  control the timing of the release and/or application of the brake relative to the speed of the escalator as detected by the escalator running relay  74  and as compared to speed match relay  76 . The relay loop  70 , in conjunction with the brake solenoid  90 , give the system the ability to stop the brake  18  outside the normal stopping time of the variable frequency drive  14 . For example, the relay loop  70  may give the system  10  the ability to stop the brake  18  approximately one second outside of the variable frequency drive  14 .  
         [0035]    Also illustrated in FIG. 4 is the schematics for the proximity switches  32  for detecting the motion of the escalator stairs and handrails. These proximity switches  32  are each connected to over speed switches  86 , which are connected to maintained contacts and switches  88  for faults relating the speed of the escalators and handrails (as shown in FIG. 6). If the motion sensors  32  detect that the hand rails and/or stairs are moving at an undesirable or unsafe rate, the switches and/or contacts  88  are opened, thereby indicating an over speed fault in the system  10 .  
         [0036]    [0036]FIG. 5 illustrates the circuitry connected to a stop button cover switch  80  and a horn  82 . This circuit extends from line  202  in FIG. 4. Although not shown, the stop button typically has a cover over the button that must be lifted in order to press the stop button. When the cover of the stop button is opened, the circuit is closed, which sounds an alarm or horn  82  to warn that the stop button may be pressed and the escalator may stop.  
         [0037]    [0037]FIG. 6 illustrates further electrical schematics for the main controller  12 , and in particular, the electrical schematics for manually selecting the direction of the escalator via switches  106  and for verifying that all faults are ready before allowing the escalator to move. When the manual switch  106  is selected to move the escalator up, the relay  102  for the escalator up closes the contact  104  in the controller  12 , which is in series with all the fault indicators. Thus, if no faults are detected, the circuit is closed and a second relay signal  108  closes all remaining maintained contacts related to the movement of the upward direction, which includes the start/stop control circuit  38  that starts the motor  16  via the variable frequency drive  18 , as illustrated by FIG. 1.  
         [0038]    Similarly, when the escalator switch  106  is selected to move the escalator down, the corresponding relay  110  closes the maintained contact  112  in series with the fault indicators. Again, if no faults are detected, a second corresponding relay signal  114  closes all the maintained contacts related to the movement of the escalator downward, including the start/stop control circuit  38  that starts the motor  16  via the variable frequency drive  18 , as illustrated by FIG. 1.  
         [0039]    As seen in FIG. 6, all of the fault ready switches are in series with the maintained contacts  104  and  112  that are closed based upon the escalator directional switches  106 . Thus, the circuit must be closed, including all the circuitry regarding the faults, to complete the circuit and to allow for the operation of the escalator. The first fault illustrated in series, in line  306 , is the emergency stop button  120 , followed by the lower end pit switch  122  and a fault reset  124 . The fault reset button  116  is represented in FIG. 8. When the fault reset button  116  is pressed, a fault reset relay  118  resets the fault reset  124  shown in line  306  to help complete the circuit.  
         [0040]    The next contact relating to a fault is the over speed ready summary, which is represented by the maintained contact  126  and which remains closed so long as the system does not detect any faults related to the speed and/or motion of the stairs or handrails. If, however, a fault is detected, the over speed relay  128  opens the contact  126 .  
         [0041]    As previously discussed, the over speed relay faults are detected by the proximity switches  32  shown in FIG. 4, which opens the contacts and switches represented in line  313  of the schematic, if a fault is detected. In addition to the motion faults detected by the proximity switches  32 , two other faults are monitored via the circuitry of line  313 , which control the over speed relay. These faults are the lower and upper missing step detectors.  
         [0042]    Proximity switches  130  and  132 , shown in line  404  and  408  of FIG. 8, detect whether a step is missing. So long as the upper sensor does not detect a missing step, the upper missing step detector switch  134  (FIG. 6) remains closed. If, however, an upper step is detected missing by the proximity switch  130 , an upper missing step detector relay  136  triggers a upper missing step detector timer  138 , which opens the switch  134  and causes the relay  128  to open the over speed ready summary maintained contact  126 . When opened, the escalator is either prevented from starting or forced to stop.  
         [0043]    Similarly, as shown in FIG. 8, the proximity switch  132  monitors the lower stairs to detect whether or not a stair is missing. If a missing stair is detected, the switch  132  triggers a relay  140  that communicates with a lower step detector timer  142 , which will open the lower missing step detector switch  144  (shown in line  313  of FIG. 6). Once the lower missing step detector switch  144  is open, the over speed relay  128  opens the over speed ready summary maintained contact  126  and the system is shut down or prevented from starting.  
         [0044]    Summaries of the upper and lower minor and major faults circuits are represented by the series of fault summary in line  306  of FIG. 6. This illustrates that all of the circuits relating to the upper and lower minor and major faults are in series and must be closed for the escalator to run under normal operating conditions. The first in the series is the upper minor faults  146 , which is represented by line  318  of FIG. 6. As illustrated by line  318 , a maintained contact  148  will remain closed if no minor faults are detected by the upper fault box  20  (See FIGS. 9 &amp;10). So long as the maintained contact  148  remains closed, the maintained contact  150  in the safety relay  152  for the upper minor faults  146  also remains closed, which completes the circuit for the upper minor faults  146  in line  306 . One additional maintained contact  154  is also provided to illuminate a light  156  on the main controller  12 , which indicates that there are no upper minor faults.  
         [0045]    [0045]FIG. 7 shows the safety relays for lower minor faults  158 , the upper major faults  160  and the lower major faults  162 . All safety relays  152 ,  158 ,  160  and  162  operate in the same manner, except that the safety relays for the upper and lower major faults  160  and  162  include fault resets  164  and  166 , respectively. Thus, when no faults are indicated from either the upper or lower fault boxes, all the maintained contacts  148 ,  168 ,  170  and  172  remain closed, which in turn keeps the maintained contacts  150 ,  174 ,  176  and  178  in the safety relays  152 ,  158 ,  160  and  162  closed. This creates a closed circuit in line  306  of FIG. 6 for the upper minor fault summary  146 , the lower minor fault summary  180 , the upper major fault summary  182  and lower major fault summary  184 . Moreover, when no minor faults are detected for the lower fault box  22 , the maintained contacts  186  and  190  in the safety relays  158  and  162  remain closed, each illuminating a light  192  and  196  on the main controller  12 . One light  192  indicates no minor faults detected by the lower fault box  22  while the other light  196  indicates that there are no major faults detected by the lower fault box  22 .  
         [0046]    The last fault ready summary in line  306  is the fault ready maintained contact for the variable speed drive  198 . Referring again to FIG. 8, if there is a fault in the variable frequency drive  14  (as determined by the circuit in FIG. 1), a relay  200  for the variable frequency drive will open the maintained contact  198  shown in line  306 , preventing the escalator from starting or from continuing to run. Similarly, so long as no fault is detected in the variable frequency drive  14 , the maintained contact  202  at line  342  of FIG. 7 will remain closed, thereby illuminating a variable frequency drive fault ready light  204 .  
         [0047]    Finally, to help troubleshoot the system, as illustrated in lines  304  and  305  of FIG. 8, upper and lower inspection switches  206  and  208  are provided to complete the circuit despite any over speed faults, upper and lower minor and major faults and/or a fault in the variable frequency drive  14 .  
         [0048]    [0048]FIGS. 9 and 10 are a schematic of the upper fault box  22  that illustrates the interlocking of the fault detectors and auxiliary switches and devices with the upper fault box  22 . As illustrated by FIG. 9, the switches for the upper minor faults  146  are all positioned in series, which as illustrated in FIG. 8, maintain the contacts for the upper minor fault box  148 , which then communicates with the safety relay for the upper minor fault box  152 .  
         [0049]    As seen in FIG. 9, common minor upper faults include those faults triggered by problems relating to the upper right handrail, upper right skirt switch, upper access cover switch, upper left skirt switch, and upper left handrail. Upper minor faults are also triggered by the engagement of the upper emergency stop switch and the motor pit stop switch.  
         [0050]    Similarly, switches for upper major faults  182  are also positioned in series, which maintain the contact  170  that communicates with the safety relay for the upper major faults  160 . These switches are for faults relating to the upper left combplate, upper right combplate, upper right out of level step detector, and upper left out of level step detector. All of the switches that relate to any major fault, including the minor faults for the handrail, must be manually reset for the system to start or resume after the fault is detected. This is indicated in FIG. 9 by the manual reset notations near the relevant switches for those particular faults.  
         [0051]    The upper fault box also communicates with an upper key switch  220  and an upper missing step proximity sensor, as shown in FIG. 9, and a stop cover button  224 , a horn  226  and motion sensor proximity switches  228 , as shown in FIG. 10.  
         [0052]    Similar to FIGS. 9 and 10, FIGS. 11 and 12 are schematics of the lower fault box that illustrates the interlocking of the fault detectors and auxiliary switches and devices to the lower fault box. As illustrated by FIG. 10, the switches for the lower minor faults  180  are all positioned in series, which as illustrated in FIG. 8, maintains the maintained contact  168  for the lower minor fault box, which communicates with the safety relay  158  for the lower minor fault box.  
         [0053]    As seen in FIG. 11, common minor lower faults  180  include those faults triggered by problems relating to the lower right handrail, lower right skirt switch, lower access cover switch, lower left skirt switch, lower left handrail. Lower minor faults are also triggered by the engagement of the lower emergency stop switch and the lower motor pit stop switch.  
         [0054]    Similarly, switches for lower major faults  184  are positioned in series, which maintain the contact that communicates  172  with the safety relay  162  for the lower major faults  184 . These switches are for faults relating to the lower left combplate, lower right combplate, lower right out of level step detector, lower left out of level step detector and lower broken step/chain switches. All of the switches that relate to any major fault, including the minor faults for the handrail, must be manually reset for the system  10  to start or resume after this type of fault is detected. This is indicated in FIG. 9 by the manual reset notations near the relevant switches for those particular faults.  
         [0055]    The lower fault box also communicates with the lower key switch  230  and the lower missing step proximity sensor  232 , as shown in FIG. 11, and the lower inspection switch  234 , lower stop cover button  236  and the horn  238 , as shown in FIG. 12.  
         [0056]    As illustrated by FIG. 13, although not necessary, the main controller  12  may also be designed to allow for installation of a microprocessor  240  that can be used to monitor the operation of the controller  12  along with monitoring external fault signals. If desired, the microprocessor  240  can be installed with an Internet or Ethernet connection  244  for central monitoring  242 . The optional microprocessor  240  will also be installed with a monitor display  246  located on the top of the main controller box  12 . The monitor  246  will allow the microprocessor  240  to display indicators for present and historical faults. The faults will be displayed in a manner to allow the user to identify a particular external fault, along with the time of fault. The display will be equipped with push buttons to allow resetting of fault history, along with manipulation of the indicators. The optional time and speed setting for energy savings may also be programmed through the display monitor.  
         [0057]    In operation, the main disconnect switch is turned on. The emergency stop push buttons  120  (FIGS. 6 &amp; 13) should be released and any fault reset buttons  124  (FIGS. 6 &amp; 13) should be reset. Both the upper inspection switch (not shown) and lower inspection switches  234  should be in the run position. The ready lights should be on for the upper and lower minor fault switches  156 ,  192  and the upper and lower major fault switches  194 ,  196 . Finally, the variable frequency drive light  204  should be on. When all these conditions have been met, the operator may then turn the spring return upper or lower switch  254  or the upper and lower switch on the control panel  106  to the up position when it is desired for the escalator to go up, or when it is desired for the escalator to go down, the spring return upper or lower switch  254 ,  106  should be turned to the down position.  
         [0058]    During approximately the first fifteen seconds when the escalator is started and running, a timer holds in the over speed relay to give the system the opportunity to reach its optimal speed. Thereafter, the relay is held in by the over speed switches  86  and the missing step detector switches  134 ,  144 .  
         [0059]    When running, if a minor fault occurs, or if the upper or lower minor fault ready light is not on when the system is first powered, the system will stop if the system is running or will not start, in the case of the initial power-up. Typically, most minor faults do not require manual reset. Thus, once a minor fault is corrected, the system will resume running upon pressing the reset button  124 .  
         [0060]    If the system detects a major fault, the system will shut down, if running, or will not start when the system is initially powered. Only after the major fault is manually reset will the system resume or start.  
         [0061]    To stop the escalator, an operator can depress the stop/fault reset pushbutton  124  on the control panel  260  of the main controller or can stop the escalator by pressing emergency stop push button  120  on the control panel  260  or at the emergency stop push buttons  250  at the top or bottom of the escalator near the handrails.  
         [0062]    It will be understood that the above-described arrangements of apparatus and the method therefrom are merely illustrative of applications of the principles of this invention and many other embodiments and modifications, include different circuit configurations and positioning and use of different switches, relays, sensors and timers, may be made without departing from the spirit and scope of the invention as defined in the claims.