Abstract:
An escalator drive assembly includes a backup member ( 40 ) that facilitates controlling movement of the escalator ( 20 ) even when the normal drive assembly operation is interrupted. A backup member ( 40 ) in the form of a flange ( 42 ) is associated with a drive pulley ( 34 ) and normally rotates in unison with the drive pulley ( 34 ). When there is a failure in the normal operation of the drive mechanism, however, there is a resulting relative movement between the backup member ( 40 ) and the drive pulley ( 34 ). Such relative motion preferably activates a switch ( 80 ) that provides a signal that indicates a failure of the normal operation of the drive mechanism. The backup member ( 40 ) facilitates providing an indication of a failure and control over movement of the escalator ( 20 ) even when the normal drive assembly is not operating as intended.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention generally relates to escalator drive mechanisms. More particularly, this invention relates to a failure detection and backup arrangement for use in an escalator drive mechanism.  
         [0002]     Escalators are passenger conveyors that typically carry passengers between landings at different levels in buildings, for example. A chain of steps typically is driven using a motorized assembly. There are a variety of motorized assemblies proposed or currently in use. There are several possible ways in which the drive torque from the motor to the step chain can be interrupted.  
         [0003]     When there is a failure of drive transmission between the motor and the step chain, there is a need to control the position of the escalator steps. Without the motive force of the motor, normal gravitational forces may cause undesirable movement of the escalator steps, for example. There is a need for an arrangement that controls movement of the escalator step chain and steps even under conditions when the normal drive mechanism cannot operate as normally intended.  
         [0004]     This invention provides a mechanism for controlling the movement of the escalator even under conditions where the normal drive arrangement cannot operate as intended. Additionally, this invention provides an indication of when the normal drive operation has failed.  
       SUMMARY OF THE INVENTION  
       [0005]     In general terms, this invention is a passenger conveyor drive assembly that includes a backup member for controlling movement or position of the conveyor even when the normal drive assembly cannot operate as intended.  
         [0006]     An assembly designed according to this invention includes a motor and a drive member that rotates responsive to a motive force from the motor. A driven member has a first portion that is engaged by the drive member such that the driven member moves responsive to movement of the drive member. When the driven member moves, that results in movement of the passenger conveyor. The backup member rotates in unison with the drive member under normal operating conditions. The backup member engages a second portion of the driven member and permits control over the driven member responsive to relative movement between the drive member and the driven member.  
         [0007]     In one example, the drive member comprises a drive pulley and drive belt. The driven member comprises a step chain, which has a plurality of links. Teeth on the drive belt engage corresponding teeth on the step chain during normal operation. In the event of a failure of the transmission of a drive force from the drive member to the driven member, at least one of the step chain links engages the backup member. Under these circumstances, the backup member, which in one example is a flange associated with the drive pulley, moves relative to the drive pulley a selected amount and then facilitates the necessary control of the escalator.  
         [0008]     When there is relative movement between the drive member and the driven member, that is an indication of a failure of the normal operation of the drive mechanism. In such circumstances, the backup member preferably engages the driven member and provides a way of controlling movement of the driven member and consequently the escalator.  
         [0009]     In one example, movement of the backup member relative to drive member activates a switch that provides a signal indicating failure of the normal, expected operation of the escalator drive assembly. In one example, the switch serves to activate a brake for stopping the escalator system.  
         [0010]     The various advantages and features of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred arrangement. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  diagrammatically illustrates an escalator system designed according to this invention.  
         [0012]      FIGS. 2A and 2B  illustrate in somewhat more detail selected components of an example escalator drive assembly designed according to this invention.  
         [0013]      FIG. 3  illustrates selected portions of the embodiment of  FIGS. 2A and 2B .  
         [0014]      FIG. 4  illustrates, in somewhat more detail, the portion of  FIG. 3  encircled in the circle labeled  4 .  
         [0015]      FIG. 5  illustrates selected features of the step chain links used in the example of  FIG. 3 .  
         [0016]      FIG. 6  illustrates selected components of another switch activating embodiment in a first position.  
         [0017]      FIG. 7  illustrates the components of  FIG. 6  in a second position.  
         [0018]      FIG. 8  diagrammatically illustrates a selected feature of another example drive member designed according to this invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     An escalator system  20  is shown in  FIG. 1  that includes a conventional escalator support structure  22  for supporting a plurality of steps  24  and a hand rail  26  to move passengers between floors in a building, for example. A drive mechanism  30  operates to move the steps  24  in a chosen direction at a desired speed under normal operating conditions.  
         [0020]     Referring to  FIGS. 2A and 2B , for example, the drive mechanism  30  includes a motor assembly  32  that preferably has a motor and a brake. The motor  32  provides a motive force to a drive pulley  34 . A cogged belt  35  ( FIG. 2A ) preferably is driven by the motor  32  and drive pulley  34 . The motive force on the belt  35  preferably is transferred to a plurality of step chain links  36 . In one example, the belt is cogged to engage a plurality of cooperatively shaped teeth  38  on the step chain links  36 . Under normal operating conditions, the belt  35  and the step chain links  36  move in unison, based upon the speed of movement of the drive pulley  34 .  
         [0021]     The illustration of  FIG. 2A  shows the drive belt  35  while the illustration of  FIG. 2B  shows the step chain links  36 . The drive belt  35  and step chain links  36  are included in an operative arrangement. The engagement between the teeth on the drive belt  35  and the corresponding teeth  38  on the step chain links  36  provides the movement of the escalator steps as the step chain links  36  are associated with the steps in a manner sufficient to cause such movement. Accordingly, the step chain links  36  preferably follow the entire path of the steps while the drive belt  35  travels around a much shorter loop as can be appreciated from  FIG. 2A , for example.  
         [0022]     A synchronizer bar  50  extends approximately the width of the steps so that drive belts  35  and sets of step chain links  36  associated with the edges of the steps, respectively, move synchronously to provide smooth and reliable operation of the conveyor.  
         [0023]     The inventive arrangement includes a backup member  40  associated with the drive pulley  34 . The backup member  40  preferably includes a flange body portion  42  with a plurality of radially extending arm portions  44 . In the illustrated example, the backup member  40  is generally star-shaped.  
         [0024]     Under normal operating conditions, the backup member  40  rotates in unison with the drive pulley  34  and has no effect on step chain movement. When there is a failure in the normal operation of the drive mechanism, however, there is relative movement between the drive pulley  34  and the step chain links  36 . Under such circumstances, a portion of at least one of the step chain links  36  engages at least one of the radially extending portions  44  on the backup member  40 . This results in at least some relative movement between the drive pulley  34  and the backup member  40 . Such relative motion between the drive pulley  34  and the backup member  40  instigates an indication that the drive assembly has failed to operate as normally desired.  
         [0025]     One example arrangement that utilizes limited relative movement between the backup member  40  and the drive pulley  34  is illustrated in  FIGS. 3 and 4 . In this example, the backup member  40  normally rotates with the drive pulley  34 . A synchronization arrangement  60  keeps the two rotating together under normal operating conditions.  
         [0026]     The backup member  40  preferably is initially oriented relative to the drive pulley so that a stop member  62 , which is a bolt secured to the drive pulley  34  in the illustrated example, is positioned against a support surface  64  within a generally arcuate slot  66  formed on the backup member  40 . The support surface  64  preferably includes a partially rounded contour to stabilize the bolt  62  against the surface  64 .  
         [0027]     A spring  70  which normally biases the backup member  40  away from the drive pulley  34  in a direction parallel to the axis of rotation of the drive pulley. In the initial normal operating position, the spring  70  operates to assist maintaining the bolt  62  on the support surface  64 . The contour of the surface  64  and the bias of the spring  70  preferably are set so that a desired minimal amount of force is required to cause movement of the bolt  62  within the slot  66 .  
         [0028]     As can be appreciated from  FIGS. 3 and 4 , a plurality of the synchronizing arrangements  60  preferably are provided spaced about on the drive pulley  34  and backup member  40 .  
         [0029]     When there is relative movement between the step chain links  36  and the drive pulley  34 , engagement between the backup member  40  and the step chain links  36  causes relative movement between the drive pulley  34  and the backup member  40 . Depending on the direction of such relative movement, the bolt  62  becomes removed from the surface  64  such that it slides into one of the ends  68  of the generally arcuate slot  66 . Such movement of the bolt  62  within the slot  66  is the result of the relative rotary movement between the drive pulley  34  and the backup member  40 .  
         [0030]     Once the bolt  62  is in one of the ends  68  of the slot  66 , the bolt is situated so that the drive pulley  34  and backup member  40  once again move synchronously or remain stopped together, depending on the operation of the motor and brake assembly  32 .  
         [0031]     In the examples of  FIGS. 3 through 5 , the radial projections  44  on the backup member  40  preferably cooperate with reference surfaces  72  that are formed on the step chain links  36 . Under normal operating conditions, the radial projections  44  follow the reference surfaces  72 . When there is relative movement between the drive pulley  34  and the step chain links  36 , the cooperation between the reference surfaces  72  and the radial projections  44  causes the relative movement between the drive pulley  34  and the backup member  40 . In one example, the teeth  38  on the step chain links  36  are formed during a casting process while the reference surfaces  72  are machined in separately.  
         [0032]     The backup member  40 , which is again synchronized with the drive pulley  34 , allows the drive assembly  30  to once again control movement of the step chain links to once again control movement of the step chain links  36 . In this condition the backup member  40  imparts the motive force of the motor to the step chain links.  
         [0033]     The spring  70  causes relative outward movement of the backup member  40  further away from the drive pulley  34  as the bolt  62  moves into an end  68  of the slot  66 . Such movement preferably activates a switch  80 . The switch  80  preferably is positioned relative to the backup member in such an embodiment so that the switch becomes activated at the time that there is relative movement between the step chain links  36  and the drive pulley  34 . Activation of the switch  80 , therefore, provides an indication of some failure in the drive connection between the drive pulley  34  and the step chain links  36 .  
         [0034]     In the illustrated example, an electrical signal generated by the switch  80  is received by a controller  82  that controls operation of the motor and brake assembly  32 . In one example, the controller  82  is an integral part of the motor assembly. The controller  82  preferably controls the operation of the motor assembly and brake to ensure that the escalator steps  24  do not move in an undesirable fashion after the normal operation of the drive assembly has been interrupted.  
         [0035]     The controller  82  may be, for example, a conventional microprocessor that is suitably programmed to interpret signals from the switch  80  and to correspondingly control the motor and brake assembly  32 . In one example, the controller  82  is part of a controller already associated with the escalator system. In another example, the controller  82  is a dedicated microprocessor. Given this description, those skilled in the art will be able to choose from among commercially available components and to suitably program a computer or controller to perform the functions required to realize the results provided by this invention.  
         [0036]     In another example, such as shown in  FIG. 2B , the radial projections  44  cooperate with one or more pins  150  associated with the step chain links  36 . In this example, some of the pins  150  can be portions of axles or pins that interconnect the plurality of step chain links  36 . As can be appreciated, a variety of configurations are within the scope of this invention for causing cooperative movement between the step chain links  36  and the backup member  40 .  
         [0037]     Another example switch activating strategy is illustrated in  FIGS. 6 and 7 . ′ In this example, a pin  160  cooperates with the switch  80  rather than cooperation directly between the flange portion of the backup member  40  and the switch  80  as occurs in the previously discussed example.  
         [0038]     The drive pulley  34  in this example preferably supports a pin  160  within a receiver portion  162 , which may be a bore in the drive pulley, for example. A biasing member  164 , such as a spring, urges the pin  160  in a direction out of the receiver portion  162 . The illustrated example of the pin  160  includes a base portion  166  and an extending arm  168 .  
         [0039]      FIG. 6  illustrates the pin  160  in a first position within the receiver portion  162 . A solid portion  170  on the backup member  40  maintains the pin  160  in a recessed position within the receiver portion  162 . An opening  172  is provided on one side of the solid portion  170  while a second opening  174  is provided on an opposite side. When there is relative rotation between the backup member  40  and the drive pulley  34 , the pin arm  168  is biased out of the receiver portion  162  and through a corresponding opening  172  or  174 . This can be appreciated from  FIG. 7 , for example.  
         [0040]     In one example, the pin base  166  and arm  168  are structurally stable enough to support the backup member  40  relative to the drive pulley  34  so that any further movement of the drive pulley  34  by the motor  32  results in movement of the backup member  40  to control movement of the escalator. In such an example, the pin  160  may work alone or in combination with a synchronizing arrangement  60  as previously discussed.  
         [0041]     In another example, the pin  160  is allowed to slide within a slot in the drive pulley  34  after the pin has extended through one of the openings in the backup member  40 . Such an arrangement is schematically illustrated in  FIG. 8  where a portion of the drive pulley  34  is shown. The receiver portion  162  extends a first depth into the drive pulley  34 . An arcuate groove  190  is coincident with the receiver portion  162  but does not extend as deep into the body of the drive pulley  34 . Therefore, when the pin is in a first position as illustrated in  FIG. 6 , it is maintained in the receiver portion  162 . After the pin  160  has extended through an opening in the backup member  40 , however, the base  166  is free to slide within the groove  190  so that there can be a desired amount relative rotation between the drive pulley  34  and the backup member  40 . Such relative rotation with the pin  160  in the groove  190  prevents the pin from being broken or sheared as a result of any forces that would cause relative movement between the backup member  40  and the drive pulley  34 . An arrangement such as that shown in  FIGS. 3 and 4  could be used to cause the backup member  40  to again move with the drive pulley  34 .  
         [0042]     This invention provides a unique backup and failure indicator arrangement for escalator drive mechanisms. This invention is especially useful for escalator drive mechanisms that include a drive belt that is actuated by a drive pulley but not limited to such arrangements.  
         [0043]     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.