Patent Publication Number: US-11390487-B2

Title: Automated elevator safety chain diagnosis

Description:
BACKGROUND 
     Elevator systems include various features to protect individuals on or near an elevator. For example, the landing doors at each landing are locked whenever the elevator car is not situated at that landing to prevent access to the hoistway. The door locks include switches that provide an indication whether the door is locked. A controller will typically prevent the elevator car from moving when any of the switches indicates that any of the landing doors is open or not locked. 
     One issue with known door lock components is that they may become misaligned or wear over time, either of which can cause the associated switch to malfunction. If any of the switches along a hoistway is not properly working the elevator car in that hoistway is taken out of service. A service technician or mechanic typically has to manually inspect each door to identify which switch is not working properly because the switches are all connected in series. Such manual inspection takes time especially in high rise buildings. 
     SUMMARY 
     An illustrative example embodiment of an elevator system includes an elevator car situated for movement among a plurality of landings. The elevator car includes a car door and a door mover. A door interlock associated with a landing door at each of the landings is configured to couple the associated landing door with the car door. The door interlocks respectively include a lock switch. A controller is configured to: cause the elevator car to move to at least one of the landings; when the elevator car is at the at least one landing, cause the door mover to instigate movement of the door interlock sufficient to at least temporarily change a position of the lock switch; and locate a malfunctioning one of the lock switches at one of the landings based on the movement of the door interlock. 
     In an example embodiment having one or more features of the elevator system of the previous paragraph, an amount of movement of the door mover that instigates the movement of the door interlock is insufficient to cause movement of the landing door at the selected landings. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the lock switches are supposed to be in a closed condition when the respective associated landing doors are closed and the malfunctioning one of the lock switches is in an open condition when the associated landing door is closed prior to the instigated movement of the door interlock. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the lock switches are connected in series in an electrically conductive circuit, when any of the lock switches is open the electrically conductive circuit is an open circuit, and the controller locates the malfunctioning one of the lock switches at one of the selected landings by determining when the electrically conductive circuit changes from an open circuit to a closed circuit responsive to the movement of the door interlock at the one of the selected landings. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the door interlocks each include a lock member, the lock switches each include a contact that moves with the lock member, and the movement of the door interlock instigated by the door mover is sufficient to cause movement of the lock member. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the lock member is moveable between a locked position and an unlocked position and the movement of the door interlock instigated by the door mover moves the lock member in a direction from the locked position toward the unlocked position. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the lock member moves into the locked position subsequent to the movement of the door interlock instigated by the door mover and the lock switch contact member moves into a position to close the lock switch as the lock member moves into the locked position. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the controller sequentially moves the elevator car from one of the landings to an adjacent one of the landings until the controller locates the malfunctioning lock switch or the elevator car has moved to all of the plurality of landings. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the controller determines whether the elevator car is empty before moving the elevator car and the controller only moves the elevator car when the elevator car is empty or an authorized override command has been provided to the controller to move the elevator car when the elevator car is not empty. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the controller stores an indication of the location of the malfunctioning one of the lock switches or provides the indication to another device accessible by an authorized individual. 
     In an example embodiment having one or more features of the elevator system of any of the previous paragraphs, the controller is configured to respond to a command from a location remote from a site of the elevator system by causing the elevator car to move and the door mover to instigate movement of the door interlocks to locate the malfunctioning lock switch prior to a technician arriving at the site of the elevator system. 
     An illustrative example embodiment of a method of analyzing an elevator system safety chain includes: moving an elevator car to at least one of a plurality of landings; instigating movement of a door interlock at the at least one of the landings sufficient to at least temporarily change a position of a lock switch at the at least one of the landings when the elevator car is at the at least one of the landings; and locating a malfunctioning lock switch at one of the landings based on the movement of the door interlock sufficient to at least temporarily change the position of the lock switch. 
     An example embodiment having one or more features of the method of the previous paragraph includes instigating the movement of the door interlock using a door mover of the elevator car and wherein an amount of movement of the door mover that instigates the movement of the door interlock is insufficient to cause movement of a landing door associated with the door interlock. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, there are a plurality of lock switches, one of the lock switches is at each of the landings, the lock switches are supposed to be in a closed condition when respective associated landing doors are closed, and the malfunctioning lock switch is in an open condition when the associated landing door is closed prior to the movement of the door interlock. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, the lock switches are connected in series in an electrically conductive circuit, when any of the lock switches is open the electrically conductive circuit is an open circuit, and locating the malfunctioning one of the lock switches comprises determining when the electrically conductive circuit changes from an open circuit to a closed circuit responsive to the movement of the door interlock at the one of the selected landings. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, the door interlock includes a lock member, the lock switch includes a contact that moves with the lock member, and the movement of the door interlock is sufficient to cause movement of the lock member. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, the lock member is moveable between a locked position and an unlocked position and instigating movement of the door interlock comprises moving the lock member in a direction from the locked position toward the unlocked position. 
     In an example embodiment having one or more features of the method of any of the previous paragraphs, the lock member moves into the locked position subsequent to the movement of the door interlock and the lock switch contact member moves into a position to close the lock switch as the lock member moves into the locked position. 
     An example embodiment having one or more features of the method of any of the previous paragraphs includes sequentially moving the elevator car from one of the landings to an adjacent one of the landings until locating the malfunctioning lock switch or the elevator car has moved to all of the plurality of landings. 
     An example embodiment having one or more features of the method of any of the previous paragraphs includes determining whether the elevator car is empty before moving the elevator car and only moving the elevator car when the elevator car is empty or an authorized override command has been provided to move the elevator car when the elevator car is not empty. 
     An example embodiment having one or more features of the method of any of the previous paragraphs includes storing an indication of the location of the malfunctioning one of the lock switches or providing the indication to another device accessible by an authorized individual. 
     An example embodiment having one or more features of the method of any of the previous paragraphs includes responding to a command from a location remote from a site of the elevator system by moving the elevator car to the landings, instigating movement of the door interlocks at the landings, respectively, and locating the malfunctioning lock switch prior to a technician arriving at the site of the elevator system. 
     The various features and advantages of at least one disclosed example embodiment will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates selected portions of an elevator system. 
         FIG. 2  schematically illustrates an example door interlock arrangement. 
         FIG. 3  is a flow chart diagram summarizing an example method of locating a malfunctioning switch in the elevator system shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of this invention facilitate diagnosing a condition of an elevator safety chain and locating a malfunctioning switch in the safety chain in an efficient manner. 
       FIG. 1  schematically illustrates selected portions of an elevator system  20 . An elevator car  22  is situated for movement among a plurality of landings  24 . The elevator car  22  includes at least one elevator door  26  that is moveable between open and closed positions by a door mover  28 . 
     At least one landing door  30  is situated at each of the landings  24 . An interlock  32  associated with each of the landing doors  30  facilitates coupling the elevator car door  26  to the landing door  30  when the elevator car  22  is situated at one of the landings  24  so that the doors  26  and  30  move together when the elevator car  22  is at a particular landing. 
     As shown in  FIG. 2 , an example door interlock  32  includes a door lock  34  and a lock switch  36 . The lock switch  36  includes a switch contact  40  that is supported on a lock member  42 . When the associated landing doors  30  are in a fully closed position, the lock member  42  is biased into a closed or locked position where the switch contact  40  closes the switch  36 . 
     When the elevator car  22  is properly situated at a landing and the elevator car door  26  is aligned with the landing door  30 , a vane  44  supported on the elevator car door  26  and the interlock  32  cause the landing doors  30  to move with the elevator car doors  26  responsive to operation of the door mover  28 . In the illustrated example embodiment, the vane  44  contacts a roller  46  to pivot the lock member  42  downward (according to the drawing) to unlock the door lock  34 . In that condition, the switch  36  is open because the switch contact  40  no longer makes electrical contact with the rest of the switch  36 . Rollers  48  and  50  cooperate with the vane  44  for moving the landing doors  30  between open and closed positions. Other types of interlocks are known and embodiments of this invention are not limited to any particular interlock configuration. 
     The lock switches  36  at each of the landings  24  are connected in series to form an electrical circuit or safety chain in a known manner. A controller  60  (shown in  FIG. 1 ) monitors the condition of the safety chain to determine whenever any of the lock switches  36  indicates that an associated door lock  34  is not in the locked condition, which typically corresponds to an associated landing door  30  being open. The controller  60  is programmed or configured to prevent movement of the elevator car  22  whenever the safety chain electrical circuit is an open circuit because at least one of the lock switches  36  is open. 
     One issue associated with many elevator door interlock configurations is that precise alignment among the components is required for the lock switch  36  to operate properly. Additionally, wear and tear on the components over time may interfere with proper function of the lock switch  36  at any of the landings  24 . The controller  60  is configured to diagnose a condition of the safety chain by locating a malfunctioning one of the lock switches  36 , which can be accomplished in partially or fully automated manner. 
     Assuming that at least one of the lock switches  36  is in an open condition when it is supposed to be closed while the associated landing doors  30  are closed, the elevator car  22  will be taken out of service by the controller  60  because the safety chain does not indicate proper door conditions along an entire hoistway. Under those circumstances, the controller  60  is configured to automatically diagnose a condition of at least some of the interlocks  32  and their associated lock switches  36  to locate the malfunctioning lock switch  36 . 
       FIG. 3  shows a flowchart diagram  70  that summarizes an example approach for diagnosing the safety chain of the elevator system  20 . The example technique is useful, for example, when at least one of the lock switches  36  is malfunctioning leaving the safety chain in an open circuit condition. In some example embodiments, the controller  60  operates in a maintenance or inspection mode that includes an ability to bypass the open circuit condition of the safety chain to allow elevator car movement even though at least one of the lock switches  36  is not in a fully closed condition. 
     At  72 , the controller  60  moves the elevator car  22  to one of the landings  24 . In some embodiments the controller  60  first determines that the elevator car is empty before commencing movement of the elevator car  22 . The load on the elevator car  22  or video information regarding the interior of the car, which can be obtained in a known manner, provides an indication whether the elevator car  22  is empty. In some cases, a mechanic or technician may want to be in the elevator car  22  during the example procedure and some embodiments accommodate this by including an override option for the mechanic to indicate to the controller  60  that moving the elevator car  22  while the mechanic is in the car is desired. This could be incorporated into an inspection mode command, for example. 
     While the elevator car  22  is situated at that landing, the controller  60  causes the door mover  28  to instigate movement of the door interlock  32 . For example, the controller  60  may cause the door mover  28  to move the elevator car door  26  and the associated vane  44  sufficiently to contact the roller  46  to pivot the lock member  42  from the locked position shown in  FIG. 2  toward an unlocked position. The door mover  28  then returns to a rest or initial position allowing the lock member  42  to return to the locked position. Such movement can tend to cause the switch contact  40  to make proper contact with the remainder of the switch  36  to close the switch. If the switch  36  was malfunctioning, such movement of the door mover  28  to instigate some movement of the interlock  32  can effectively at least temporarily restore the switch  36  to a properly closed condition, which completes or closes the circuit of the safety chain. 
     The amount of movement of the door mover  28  is sufficient to cause some movement of the components of the interlock  32  without causing movement of the landing doors  30 . Many elevator door interlock arrangements are designed so that there is some movement of the interlock components to unlock the door, for example, prior to any movement of the landing doors  30 . Using such a small amount of movement of the door mover  28  facilitates keeping the hoistway doors  30  closed so as not to disturb or alert anyone who may be near a landing  24  where the elevator car  22  is situated. 
     At  76 , the controller  60  determines whether the safety chain circuit has closed as a result of the instigated movement of the interlock  32 . If the safety chain circuit is now a closed circuit, that indicates that the switch  36  at that landing  24  was the one causing the open safety chain circuit condition. In other words, the switch  36  at that landing  24  is the malfunctioning switch. At  78 , the controller  60  locates the malfunctioning lock switch  36  at the current landing  24  where the elevator car  22  is positioned. The controller  60  is aware of the location of the elevator car  22  using known techniques. 
     Once the malfunctioning lock switch has been located, the controller  60  stores or provides an indication of that information so that it is accessible by a mechanic who can address the condition of the interlock  32  and the lock switch  36  at the appropriate landing  24 . At  80 , the controller  60  exits the automated diagnosis mode. 
     In many instances, the elevator car  22  will have to travel to multiple landings  24  before a malfunctioning lock switch will be located. The example technique summarized in  FIG. 3  includes continuing to move the elevator car  22  to an adjacent landing  24  as long as all of the door interlocks  32  have not yet been checked as shown at  82 . Since the controller  60  may locate or identify the malfunctioning lock switch  34  before checking every interlock at every one of the landings  24 , only a selected subset of the landings  24  may be involved in a particular diagnostic procedure. 
     In some example embodiments, the controller  60  is configured to receive a command to perform the automated diagnosis from a remote location. For example, a mechanic or technician traveling to the site of the elevator system  20  may use a communication device, such as a mobile phone, to send a signal or command to the controller  60  to locate the malfunctioning lock switch  36 . The controller  60  automatically locates the malfunctioning lock switch and either communicates that information to the device that issued the command or stores that information in a manner that is accessible to the technician or mechanic once that individual arrives at the site of the elevator system  20 . 
     In some example embodiments, the controller  60  automatically instigates the diagnosis procedure based on detecting that there is a fault in the safety chain. For example, when the controller  60  determines that the safety chain indicates that at least one door is not locked when all doors are expected to be locked, the controller  60  conducts the process summarized in  FIG. 3 . The information regarding the located malfunctioning lock switch  36  may be stored by the controller  60 , communicated to a remote device for access by a technician or mechanic, or both. 
     While the above technique is described as being useful for locating a malfunctioning lock switch, the diagnosis technique identifies a malfunctioning interlock  32  or door lock  34  that may require repair or adjustment because the condition and operation of those components affects the ability of the lock switch  36  to properly close to complete or close the circuit of the safety chain. 
     By automating the diagnosis of the safety chain and interlocks, it is no longer necessary for a mechanic or technician to manually inspect each of them to locate which of the lock switches  36  is malfunctioning. The automated diagnosis of an embodiment of this invention improves efficiencies associated with elevator system maintenance and restoring an elevator to service. 
     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 necessarily 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.