Abstract:
An elevator moves through a hoistway with one or more sensors positioned so that they pass by one or more targets that are in fixed positions relative to the hoistway. As they pass, an inductive current is generated, giving the elevator&#39;s control circuitry precise information as to the vertical position of the elevator car. The control system adjusts the raising and/or lowering of the elevator car based on that position information and any discrepancy between it and the supposed position at which the control system had believed the car was. Discrepancies are accumulated over time as an indication of cable stretch, and when the stretch exceeds a particular threshold, an alarm is raised for maintenance. The control system also defines a “door zone” around each landing where, based on the precise height measurement achieved herein, it is safe under the circumstances to open the doors of the car.

Description:
FIELD 
       [0001]    The present disclosure relates to elevators. More specifically, the present disclosure relates to devices for indicating or signaling operating conditions, in particular, the position of an elevator car. 
       BACKGROUND 
       [0002]    In the field of elevators, it is desirable to control the position of an elevator car so that the floor of the passenger cabin is aligned with the floor of the building when passengers enter and exit the car. While there may be devices and methods that attempt to accomplish this, it is believed that no one prior to the inventor(s) has made or used an invention as described herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    It is believed that the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements. 
           [0004]      FIG. 1  is a schematic diagram of a portion of the control system used in some embodiments of the present system. 
           [0005]      FIG. 2  is an elevational view of a sensor/target combination used in some embodiments of the present system. 
           [0006]      FIG. 3  is an elevational view of another sensor/target combination used in some embodiments of the present system. 
           [0007]      FIG. 4  is an elevational view of a third sensor/target combination used in some embodiments of the present system. 
           [0008]      FIG. 5  is an elevational view of a fourth sensor/target combination used in some embodiments of the present system. 
           [0009]      FIG. 6  is a side view of an elevator system that includes structures, components, and features common to many embodiments of the present system. 
       
    
    
       [0010]    The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the descriptions serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown. 
       DESCRIPTION 
       [0011]    The following description and certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled in the art from the following description. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive. 
         [0012]    Generally, one embodiment of the present system is an elevator with a control system that manages its movement and position as a function of signals from inductive sensors configured to pass ferrous metal targets at or around one or more floors. The sensor includes one or more conductors situated in a plane along a spiral path. Alternative embodiments include multiple inductive sensors and/or multiple targets for redundancy and increased accuracy. Other features of certain embodiments include adjusting control of the elevator car to compensate for differences between the expected position (based on movement of the control system) and the actual sensed position, and such adjustments can be accumulated to raise an alarm when cable stretch requires maintenance. Further, adjustments to leveling can be made without the need to enter the hoistway and relocate or reposition sensors and/or targets. Yet another feature defines a “door zone” or “door zone length” defined based on sensor outputs and user input that can be varied or resized dynamically. Still yet, another feature allows the inductive sensing system to operate in an emergency rescue mode when the primary control system may be inoperable such that the elevator(s) can be accurately driven and positioned at floors based on the inductive sensing system so that would-be passengers at a given floor can be evacuated from the building. 
         [0013]    For the purpose of clarity, certain terms used in the description above should be understood as having particular meanings. Thus, the phrase “based on” is used as an indication that something is determined at least in part by the thing that it is identified as being “based on.” When something is completely determined by a thing, it will be described as being “based exclusively on” the thing. Also, the verb “determine” should be understood to refer to the act of generating, selecting or otherwise specifying something. For example, to obtain an output as the result of analysis would be an example of “determining” that output. As a second example, to choose a response from a list of possible actions would be a method of “determining” an action. 
         [0014]    The phrase “door zone” in the context of an elevator car control system refers to a vertical position of the elevator car that is close enough to dead level with a landing for doors to be safely opened given the current control context (which might include, for example, normal operation, hospital operation, emergency operation, and firefighter control mode, to name just a few examples). The term “alarm” refers to a human-perceivable indication of a condition. For example, an alarm might be a smart phone notification, a sound, a light, a vibration or vibration pattern, an email message, or other indication as will occur to those skilled in the art. 
         [0015]    The term “target” in the context of this disclosure refers to one half of a sensor/target pair that is activated by means of relative movement between the two. In some embodiments, the sensor/target pair matches a conductive coil with a rectangular plate of ferrous metal, one of them is called the sensor, and the other is called the target. In other embodiments, the sensor is a coil of conductive material, and the target is a structural piece of ferrous metal, such as a door frame, sill plate, or another steel part of a hoistway door (or even the door itself). In systems where the target is the hoistway door or another fixed component of the elevator like the sill plate or door frame, only the sensor position is adjustable for gross level adjustment if necessary. In systems where the target is a mounted plate of some kind, then both the target position and the sensor position can be adjustable for gross leveling adjustment if necessary. Fine level adjustment can be achieved by adjusting the door zone length as an input to the system such that these adjustments to achieve dead level can be attained without entering the hoistway and repositioning sensors and/or targets. 
         [0016]    The overall context of some embodiments of the present system is illustrated in  FIG. 6 . System  100  includes car  102  that is moved up and down through hoistway  104  by a lift mechanism  106 . Lift mechanism  106  can take any of the multitude of forms, as will occur to those skilled in the art. Nonlimiting examples include hydraulic lifts, traction lifts, belt lifts, and drum lifts. Traveling in connection with car  102  is sensor  108 , which has a configuration adequate to inductively detect movement of sensor  108  past metal target  110 . 
         [0017]    In the illustrated embodiment, targets  110  are positioned in proximity with each floor served by car  102 , but in other embodiments targets are placed at only a subset of the floors served by car  102 . In still other embodiments, targets are placed in locations not associated at all with a floor served by car  102 . 
         [0018]    While  FIG. 6  illustrates sensor  108  as being suspended from car  102  by strut  112 , sensor  108  can alternatively be placed directly on the side of car  102 , above car  102 , or in any other location proximal to car  102  so that sensor  108  moves through hoistway  104  along with car  102 . Those skilled in the art will understand there to be many options for how and where sensor  108  is placed in view of this disclosure. 
         [0019]    In the present example, control system  114  is configured as the primary system for operating car  102  and positioning car  102  within hoistway  104  at landings of various floors without relying on information from sensor  108  and target  110 . However, sensor  108  and target  110  are used as a way of confirming the position that control system  114  would abide by if operated completely independently from sensor  108  and target  110 . And, actions and adjustments can be performed if warranted based on the confirmatory information from sensor  108  and target  110 . Those skilled in the art will understand the available control systems  114  that act as a primary system for operating an elevator. 
         [0020]    In the present example, control system  114  controls lift system  106 , causing it to raise and lower car  102  based on a variety of inputs and conditions. One of those inputs in the illustrated embodiment is a signal from sensor  108  that indicates the position of sensor  108  relative to a target  110 . Other inputs may include passenger controls inside car  102  (not shown), elevator call buttons on each floor adjacent to hoistway  104  (not shown), outputs from RFID interrogator  116  and tag  118  or other location identity reading apparatus. Control system  114  processes these inputs to generate outputs for controlling lift system  106  and for other purposes as is understood by those skilled in the art. In various embodiments, this processing occurs in a general-purpose processor in communication with the memory that is encoded with programming instructions executable by the processor to achieve the described functionality. In other embodiments, the processing is managed by an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other circuitry as will occur to those skilled in the art. This processing portion of control system  114  may be comprised of one or more components configured to operate as a single unit. When of a multi-component form, the processor may have one or more components located remotely relative to the others. One or more components of the processor may be of the electronic variety including digital circuitry, analog circuitry, or both. In some embodiments, the processor is of a conventional, integrated circuit microprocessor arrangement. In alternative embodiments, one or more reduced instruction set computer (RISC) processors, application-specific integrated circuits (ASICs), general-purpose microprocessors, programmable logic arrays, or other devices may be used alone or in combination as will occur to those skilled in the art. 
         [0021]    Some of the logic circuitry in control system  114  for this exemplary embodiment is illustrated in  FIG. 1  and will be discussed with continuing reference to  FIG. 6 . Control system  200  in this embodiment includes CPLD and/or FPGA logic unit  202 , which takes input from inductive position sensor  204 , floor identification sensor  206 , dead-level calibration input  208 , and door zone distance input  210 . Logic unit  202  produces door zone safety output  212  and absolute position output  214  using logic that will occur to those skilled in the art in view of this disclosure. 
         [0022]    Inductive position sensor  204  produces one or more outputs as a function of its movement relative to a ferrous metal target  216  positioned along the outside of hoistway  104  (see  FIG. 6 ). In some embodiments, position sensor  204  produces an analog signal corresponding to the amount of overlap between position sensor  204  and a metal target  216 , so that as car  102  moves along hoistway  104  and inductive position sensor  204  moves past metal target  216 , the signal increases from a low value to a peak value, maintains that peak value as long as all of position sensor  204  is next to target  216 , then falls again to the low value as the overlap between the components reduces to zero. Alternatively or additionally, position sensor  204  produces digital output that indicates the amount of overlap between position sensor  204  and target  216 . The digital signal might simply be a binary value that has one value while position sensor  204  is overlapping target  216  to at least a threshold extent, and the other value at other times. Sometimes, however, the digital output of position sensor  204  has a greater number of possible levels (for example, 4, 8, 12, 16, 32, or other number of discrete values) selected as a function of the amount of overlap. 
         [0023]    Floor identification sensor  206  also produces an output that is taken as an input to logic unit  202 . Floor identification sensor  206  provides some means for logic unit  202  to identify the particular floor, landing, or other known position within hoistway  104  where car  102  is currently located. Any of a variety of technologies can be used for floor identification, such as RFID technology, magnetic encoding, a vane system, or other floor identification technique as will occur to those skilled in the art. In some versions, the identification of a specific floor is not required and the focus is instead on identification of a floor generally and ensuring that the elevator is level with the floor when stopping at that particular floor. In such instances the primary control system will have other means for determining absolute position of the elevator within the hoistway. The door zone positioning system  200  then operates as a confirmation that indeed the elevator is positioned properly, and in particular properly relative to the floor landing. 
         [0024]    Door zone safety output  212  of logic unit  202  in this embodiment is a binary output used in the elevator system  100  to determine whether it is safe for the doors of car  102  to be opened because, for example, car  102  is or is not close enough to a dead-level position with respect to a landing. As those skilled in the art will understand, the signal may be overridden in certain circumstances, but is used as a logical input to other circuitry (not shown). In alternative embodiments, door zone safety output  212  is a multi-bit value that indicates whether car  102  is within the defined “door zone” for each of a plurality of situations—for example situations requiring car  102  to be within two inches of dead-level for instance compared to situations requiring car  102  to be within some other amount of dead-level. 
         [0025]    In some versions, absolute position output  214  of logic unit  202  provides another input to the control logic of system  100 , carrying relatively high-resolution data concerning the detected position of car  102  (determined based on the inputs to logic unit  202  like floor identification sensor  206  and others). In some embodiments, control system  114  maintains state information about the expected position of car  102  within hoistway  104  as control system  114  instructs lift mechanism  106  to raise and lower car  102 . When control system  114  receives absolute position output  214 , it compares this sensor-based value with the expected position state data and notes any corrections that need to be made to cause lift mechanism  106  to compensate for the difference. Such corrections in position can be made automatically by control system  114  or can be noted and manually input at that or a later time. 
         [0026]    In some embodiments, control system  114  keeps track of these adjustments over time as a measurement of the amount of stretch being experienced by cables used in holding and moving car  102 . In some of these embodiments, the accumulated stretch amount is reported on diagnostic devices. In some embodiments, when the accumulated stretch exceeds a certain value, and alarm is raised for maintenance of the elevator system  100  to replace the cable(s) or otherwise deal with the cable stretch. 
         [0027]    In one exemplary mode, system  200  provides a way to vary or resize a door zone length dynamically, without the need to physically reposition targets and/or sensors. In such examples, door zone distance input  210  is an input to logic unit  202  that can be set as desired. For instance, in a normal office building environment the acceptable door zone length may be six inches. Thus so long as the floor of the elevator car is within six inches of the landing floor, also stated as within six inches of dead-level, the elevator car doors and hoistway doors will open such that passengers can enter and exit. In a hospital environment, the acceptable door zone length may be only two inches for instance. System  200  allows the door zone distance or length to be changed from six inches to two inches for example by changing the input to door zone distance input  210 . Based on the known configuration and position of sensor and target pairs (e.g.  220 ,  230 ,  240 ,  250  as shown in  FIGS. 2-5 ) relative to the hoistway and landing layout, and based on position sensor  204  producing output that indicates the amount of overlap between position sensor  204  and target  216  as described above, logic unit  202  is programmed to compare the door zone distance input  210  with the inductive position sensor  204  and target  216  information. The elevator doors can be controlled based on this comparison such that the door zone safety output  212  is enabled when the information or data from the sensor target pairs indicates that car  102  is within the door zone distance input  210  and disabled when not within the door zone distance input  210 . When enabled, the car doors are permitted to open to accept entering or exiting passengers, and vice versa when disabled. In such a comparison, car  102  is within the door zone distance input  210  when the floor of car  102  is within the specified distance of the landing floor. In view of the teachings herein, other ways to enable a variable door zone distance will be apparent to those of ordinary skill in the art 
         [0028]    In one exemplary mode, system  200  provides a way to adjust leveling without the need to physically move, reposition, or relocate sensors or targets within the hoistway. In such examples, an initial setup has dead-level being when the target is in the middle of the sensor. Furthermore, in this example the door zone length is initially set to eight inches—thus four inches above and four inches below the middle of the sensor. For various reasons apparent to those skilled in the art, like rope stretch and others, what is dead-level initially may change. So in this example, after the initial setup and some time and rope stretch, without corrective action, the primary control system delivers the elevator slightly below the floor landing level. System  200  can detect this off level since when the elevator stops at the floor, the target is not in the middle of the sensor. System  200  can then create an alert or notification to prompt adjustment either automatically or manually. 
         [0029]    Referring to  FIG. 3  by way of example only and not limitation, sensor head  232  has five conductors  231 ,  233 ,  235 ,  237 ,  239  and target  234  that is sized to match the length of sensor head  232 . Each conductor of sensor head  232  will produce the same signal reading when target  234  overlaps all conductors. In this configuration, the initial dead-level setting could be set such that when the primary control system delivers the elevator car dead-level with the floor, all conductors overlap target  234 . After time and rope stretch, the primary control system delivers the elevator slightly below dead-level with the floor. System  200  detects this because when the elevator stops at the floor not all five conductors yield the same signal since not all five conductors have overlap with target  234 . 
         [0030]    In some systems without system  200 , the elevator could be returned to dead-level by adjusting the position of certain other targets and sensors within the hoistway that work with the primary control system. In the systems with system  200 , this can be accomplished by resizing the door zone length without entering the hoistway. For instance the door zone length can be adjusted by e.g. adjusting the top of the zone downward (DZD adjustment) and/or adjusting the bottom of the zone upward (DZU adjustment). Unless the DZD and DZU are adjusted by the same amount, when resizing door zone length, the center or middle of the resized door zone would move up or down relative to the previous center or middle of the prior sized door zone length. In the present example dead-level can be attained again without the need to enter the hoistway and move the physical position of targets and/or sensors. More specifically, door zone distance input  210  can be adjusted to resize (and in this case decrease) the door zone length for example to compensate the fact that dead-level is no longer in the middle of the sensor. The door zone distance input  210  could be a series of binary inputs or transferred to system  202  in a digital format. Once the elevator is returned to dead-level, the dead-level calibration input  208  is asserted to identify to system  202  the current location of dead-level. 
         [0031]      FIG. 2  illustrates a combination sensor and target for use with various embodiments of the present system. Sensor/target pair  220  includes sensor coil  222  and target  224 . Sensor coil  222  in this embodiment follows a spiral path, forming a generally rectangular overall shape oriented so that its vertical extent is greater than its horizontal extent. Target  224  in this embodiment is made of ferrous steel and mounted relative to each landing so that as sensor coil  222  passes by (in connection with car  102 ), sensor coil  222  moves near to target  224  and passes it in a direction perpendicular to the longest dimension of target  224  and along a path such that at least substantially all of coil  222  moves by in front of some portion of target  224 . 
         [0032]      FIG. 3  illustrates another combination sensor and target for use with various embodiments of the present system. Sensor/target pair  230  includes sensor head  232  and target  224 . Sensor head  232  in this embodiment includes five conductors ( 231 ,  233 ,  235 ,  237 , and  239 , respectively), each following a spiral path and forming a generally square or rectangular overall shape. Together, conductors  231 ,  233 ,  235 ,  237 , and  239  form sensor head  232  in this embodiment. Target  234  in this embodiment is made of a ferrous metal and mounted relative to each landing so that as sensor head  232  passes by (in connection with car  102 ), sensor head  232  moves near to target  234  and passes it in the direction parallel to the longest dimension of target  234  and along a path such that at least substantially all of sensor head  232  moves by in front of some portion of target  234 . In this embodiment, logic unit  202  has more information about the exact location of car  102  because of the individual signals provided by conductors  231 ,  233 ,  235 ,  237 , and  239 . 
         [0033]      FIG. 4  illustrates yet another combination sensor and target for use with various embodiments of the present system. As with the sensor/target pairs discussed above, target  244  is mounted in hoistway  104  at a location corresponding to each floor level, at particular locations where detailed location information is desirable, and/or where such mounting is convenient. In this variation, however, a redundant pair of single coils  222  and  226  are mounted on or in association with car  102  at approximately the same height. Coils  222  and  226  feed individual control circuitry for purposes of redundancy, as will be understood by those skilled in the art. In this variation, both coils  222  and  226  pass by each target  244  at the same time, so a failure of one redundant system or the other can be detected as a difference between the received outputs of the associated sensor circuits. 
         [0034]      FIG. 5  illustrates still another combination sensor and target for use with various embodiments of the present system. Here, combination  250  includes redundant sensor sets  252  and  256 , plus expanded target  254 . Each sensor set  252  and  256  comprises a plurality of individual coils, and the sets are offset vertically so that no two individual coils are in the same position relative to target  254  at the same time. Signals generated by this configuration can thus be used to achieve greater precision in detection of location by leveraging the distinct vertical locations of each coil, and/or they can be processed to provide redundancy by interpolating the expected times of peak values between adjacent coils in one set versus the actual peak provided by the intervening coil in the other set. Such processing techniques are within the skill of those in the art in view of this disclosure. 
         [0035]    Having shown and described various embodiments of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, embodiments, geometries, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not required. Accordingly, the scope of the present invention should be considered in terms of any claims that may be presented and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.