Abstract:
A ropeway may include at least one cable. A first sensor and a second sensor may be provided. The second sensor may be located between the first sensor and the cable. Related methodology is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This is a continuation of application Ser. No. 10/738,107, filed Dec. 16, 2003, now U.S. Pat. No. 7,408,474 for SENSOR DAMAGE INDICATOR AND METHOD of Jeremiah Daniel Frazier and Brian Christopher Kelly, the entirety of which is hereby incorporated by reference for all that is disclosed therein. 

   BACKGROUND 
   Aerial ropeway transportation systems are utilized for moving objects, commonly people. Examples of aerial ropeway transportation system are ski-lifts, fixed and detachable chairlifts, gondolas, aerial tramways and skyrides. 
   Sensors (e.g. proximity sensors) are utilized in aerial ropeway transportation systems to monitor performance. These sensors can be damaged if they are struck by another object. A damaged sensor may affect operability of the aerial ropeway transportation system until the sensor is replaced. 
   BRIEF SUMMARY 
   In one exemplary embodiment, methods and apparatus for indicating damage to a sensor may include a sensor damage indicator including a frangible conductor. 
   In another exemplary embodiment, an exemplary sensor may include: a sensor conductor operably associated with the sensor; and a frangible conductor attached to the sensor conductor. 
   In another exemplary embodiment, a method of indicating impact to a sensor may include: providing a conductor operably associated with the sensor; and indicating the impact by monitoring the conductor. 
   In another exemplary embodiment, an aerial ropeway may include: a sensor; a signal conductor operably associated with the sensor; and an impact conductor attached to the signal conductor. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The following Figures of the Drawing illustrate exemplary embodiments of the present sensor damage indicator. 
       FIG. 1  is a perspective view of an exemplary type of aerial ropeway transportation system. 
       FIG. 2  is a perspective view of a plurality of sheaves of the aerial ropeway transportation system of  FIG. 1 . 
       FIG. 3  is a side elevation view of the plurality of the sheaves of the aerial ropeway transportation system of  FIG. 2 . 
       FIG. 4  is a side elevation view of an exemplary sensor provided with an exemplary damage indicator. 
       FIG. 5  is a side elevation view of the exemplary damage indicator of  FIG. 4 . 
       FIG. 6  is a perspective view of the exemplary damage indicator of  FIG. 5 . 
       FIG. 7  is an exemplary wiring diagram for the exemplary sensor and exemplary damage indicator of  FIG. 4 . 
   

   DETAILED DESCRIPTION 
   Described herein are devices and methods for indicating damage to a sensor. These devices indicate that the sensor may have received a damaging impact from another object by monitoring a frangible conductor. 
     FIG. 1  shows one exemplary application for the damage indicator  100  ( FIG. 4 ); this exemplary application is an aerial ropeway  10 . With reference to  FIG. 1 , the aerial ropeway  10  may include a plurality of support towers (e.g. support tower  12 ) secured to earth at predetermined distances apart depending on application. 
   Each support tower, such as support tower  12 , may be provided with a crossbar member  14  and a plurality of sheaves  16 . The crossbar member  14  is somewhat rigidly attached to the support tower  12 . The plurality of sheaves  16  (e.g. individual sheaves  18  and  28 ) are rotationally attached to the crossbar member  14 . 
   The aerial ropeway  10  may be further provided with a haul rope cable  30 . The haul rope cable  30  may be formed from any of a number of materials, however it is commonly manufactured from braided steel. The haul rope cable  30  may be supported by the plurality of sheaves  16  in a manner that allows the haul rope cable  30  to move relative to earth. 
     FIG. 2  shows a magnified portion of the individual sheaves  18  and  28  attached to the crossbar member  14 . It should be noted that the plurality of sheaves  16  may be substantially similar to each other; therefore, the following description of individual sheave  18  is adequate for describing other sheaves (e.g. individual sheave  18 ). With reference to  FIG. 2 , individual sheave  18  may be provided with a first axis  20 , a first face  22 , a second face  24  and a track  26 . The first and second faces  22 ,  24  may take the form of circles formed parallel to and oppositely disposed from each other. The first axis  20  may be located at the center of the faces  22 ,  24 . The track  26  may be formed as a semicircle and positioned  30  concentric to the first axis  20 . Furthermore, the semicircular configuration of the track  26  may accept the haul rope cable  30 . 
     FIG. 3  illustrates a side elevation view of the individual sheaves  18 ,  28 . With reference to  FIG. 3 , the haul rope cable  30  contacts the plurality of sheaves  16  (e.g. individual sheave  18 ). In particular, individual sheave  18  contacts the haul roped cable  30  at the track  26 . 
   With continued reference to  FIG. 3 , the aerial ropeway  10  may be provided with a cable positioning switch system  50 . The cable positioning switch system  50  may be provided with a mounting bracket  52 , a proximity sensor  54 , a first nut  56  and a second nut  58 . The mounting bracket  52  may be rigidly attached to the crossbar member  14 . The proximity sensor  54  may be adjustably affixed to the mounting bracket  52  with the nuts  56 ,  58 . 
   One exemplary type of proximity sensor  54  is an inductive proximity sensor that is a non-contact proximity sensor. One commercially available proximity sensor is manufactured by Allen-Bradley of Milwaukee, Wis. and identified by part number 871T-DX50-H2. Another commercially available proximity sensor is manufactured by Efector of Exton, Pa. and identified by part number 1B5163. The exemplary proximity sensor  54  creates a radio frequency field (RF) with an oscillator and a coil. An inductive proximity sensor  54  may include an LC oscillating circuit, a signal evaluator, and a switching amplifier. The coil of this oscillating circuit generates a high-frequency electromagnetic alternating field. This field is emitted at the sensing face of the proximity sensor  54 . If a metallic object (e.g. haul rope cable  30 ) nears the sensing face, eddy currents are generated thereby drawing energy from the oscillating circuit and reducing the oscillations. The signal evaluator behind the LC oscillating circuit converts this information into a clear signal. Inductive proximity sensors  54  may switch an AC load or a DC load. DC load configurations can be NPN or PNP. NPN is a transistor output that switches the common or negative voltage to the load; load connected between proximity sensor output and positive voltage supply. PNP is a transistor output that switches the positive voltage to the load; load connected between sensor output and voltage supply common or negative. Wire configurations are 2-wire, 3-wire NPN, 3-wire PNP, 4-wire NPN, and 4-wire PNP. 
     FIG. 4  illustrates a side elevation view of the proximity sensor  54 . With reference to  FIG. 4 , the proximity sensor  54  is provided with electrical leads  60  such as first lead  62  and second lead  64 . The illustrated embodiment shows a 2-wire configuration; it is to be understood that the present damage indicator  100  and methods associated therewith may be adapted to other types of fragile sensors. In a process that will be described later herein, the proximity sensor  54  may be mounted somewhat close to the haul rope cable  30  as illustrated in  FIG. 3 . With reference to  FIG. 3 , if the haul rope cable  30  moves from the track  26 , the proximity sensor  54  generates a signal indicating this movement. In some cases, movement of the haul rope cable  30  may reduce operability of the aerial ropeway  10 . 
   With continued reference to  FIG. 3 , the location of the proximity sensor  54  renders it vulnerable to being damaged. One form of damage to the proximity sensor  54  is an impact (by objects such as, for example, ice, tools, ladders, brackets, etc.) to the proximity sensor  54 . The previously-described internal components of the proximity sensor  54  are somewhat fragile. If these internal components are damaged by an impact, the proximity sensor  54  may send erroneous information about the location of the haul rope cable  30 . In order to reduce the risk of sending erroneous information about the location of the haul rope cable  30 , the present sensor damage indicator  100  may be incorporated into (or alternatively attached to) the proximity sensor  54 . 
   With reference to  FIG. 4 , the damage indicator  100  may be positioned on the proximity sensor  54 .  FIG. 5  illustrates a side elevation view of the damage indicator  100  of  FIG. 4 . With reference to  FIG. 5 , the damage indicator  100  may be provided with a top portion  102  and an oppositely disposed bottom portion  104 . The bottom portion  104  may be formed as a threaded nut  106 . The threaded nut  106  may be provided with a threaded portion  108  ( FIG. 6 ) formed on the interior portion thereof. The threaded nut may also be provided with a flat-surfaced potion  110  formed on the exterior portion thereof. 
     FIG. 6  illustrates a perspective view of the damage indicator  100 . With reference to  FIG. 6 , the damage indicator  100  may be further provided with a plurality of stanchions  120  such as first stanchion  122 , second stanchion  124 , third stanchion  126  and fourth stanchion  128 . The stanchions  120  may protrude from the threaded nut  106  formed at the bottom portion  104  towards the top portion  102  as illustrated in  FIG. 6 . 
   With continued reference to  FIG. 6 , the damage indicator  100  may be provided with a plate  130 . The plate  130  may be attached to (or integrally formed with) the stanchions  120 . The plate  130  may be provided with a plurality of crush zones  132  such as first crush zone  134 , second crush zone  136 , third crush zone  138  and fourth crush zone  140 . The plate  130  may be further provided with a plurality of frangible lines  150  such as first frangible line  152 , second frangible line  154 , third frangible line  156  and fourth frangible line  158 . The first frangible line  152  may separate the first and second crush zones  134 ,  136 . The second frangible line  154  may separate the second and third crush zones  136 ,  138 . The third frangible line  156  may separate the third and fourth crush zones  138 ,  140 . The fourth frangible line  158  may separate the fourth and first crush zones  140 ,  134 . These frangible lines  150  may, for example, be areas where material is removed from the plate  130  (e.g. the frangible lines  150  may be detents molded into the plate  130  when manufactured). 
   With continued reference to  FIG. 6 , the damage indicator  100  may be further provided with a frangible conductor  170 . This frangible conductor  170  may be composed of any conductor such as, for example, copper wire, conductor paths on printed circuit board, silver wire, metallic wire of any type, etc. In one exemplary embodiment, the frangible conductor  170  may be wire between 22 to 18 American Wire Gage (0.0253-0.0403 inches in diameter). The frangible conductor  170  may define a first end  172  and a second end  174 . The frangible conductor  170  may be attached to (or integrally formed with) the plate  130  as illustrated, for example, in the exemplary pattern indicated by the dashed line in  FIG. 6 ; It should be noted that as illustrated in  FIG. 6 , the frangible conductor  170  may overlap frangible portions of the damage indicator  100  (e.g. the frangible lines  150 ). 
   With reference to  FIG. 7 , the aerial ropeway  10  ( FIG. 1 ) may be further provided with a cabinet  180 . The cabinet  180  may be provided with a high voltage side and a low voltage side. The high voltage side may include high-power components such as a main circuit breaker, a main contactor, a regenerative bridge, etc. The low voltage side may include low-power components that control and monitor all the functions of the aerial ropeway  10 . Examples of low-power components include, but are not limited to, the cable positioning switch system  50  ( FIG. 3 ), derailment detectors, stop buttons, end-track device safeties returns, anemometers, wind vanes, telephone and any other information transmission devices, are connected through these wires to the cabinet  180 . These various low-power components may be connected to the cabinet  180  through wires located in a communication cable  182  ( FIG. 1 ). 
   Having provided detailed descriptions of exemplary components of the present damage indicator  100 , an exemplary assembly thereof will now be provided.  FIG. 7  illustrates one exemplary assembly and wiring configuration for the damage indicator  100  and the proximity sensor  54 . With reference to  FIG. 7 , the damage indicator  100  may be threadingly engaged to the proximity sensor  54 . This engagement may occur by rotating the damage indicator  100  while contacting the proximity sensor  54  to cause the threaded portion  108  ( FIG. 6 ) of the damage indicator  100  to capture the proximity sensor  54 . The resulting combination of the damage indicator  100  and the proximity sensor  54  is illustrated in  FIG. 4 . 
   With continued reference to  FIG. 7 , after physically assembling the damage indicator  100  to the proximity sensor  54 , the electrical components thereof may be attached. It should be noted that the following description of wiring is provided for illustrative purposes only and that other wiring approaches may be utilized (e.g. the proximity sensor  54  may be of the three-wire type, the damage indicator  100  may be direct-wired to the cabinet  180 , etc.). The first lead  62  of the proximity sensor  54  may be electrically interfaced with the cabinet  180 . The second lead  64  of the proximity sensor  54  may be electrically interfaced with the first end  172  of the frangible conductor  170 . The second end  174  of the frangible conductor  170  may be electrically interfaced with the cabinet  180 . It is to be understood that this electrical interfacing may occur through various electrical components such as, for example, bus bars, wires, the communications cable  182  ( FIG. 1 ), etc. 
   When utilized to indicate damage to the proximity sensor  54 , the damage indicator  100  may be utilized as an ‘impact fuse’. As used herein, the term impact fuse describes any device capable of indicating to the cabinet  180  (controller) that the proximity sensor  54  has been impacted. As illustrated herein, the impact fuse may take the form of the damage indicator  100  illustrated in the figures of the drawing as well as other embodiments not illustrated in the drawing. 
   When the proximity sensor  54  is impacted, the plate  130  will rupture. This rupture may occur, for example, at the frangible lines  150 . This rupturing of the plate  130  causes the frangible conductor  170  to break (thereby disrupting the conductivity of the frangible conductor). Therefore, before the impact, an indicator signal may travel from the first end  172  to the second end  174  of the frangible conductor  170  (sometime referred to herein as a first condition of the damage indicator). After impact, the indicator signal cannot travel along the frangible conductor  170  (sometime referred to herein as a second condition of the damage indicator). This disruption of the indicator signal may be detected by the circuitry within the cabinet  180  ( FIG. 7 ). 
   In one exemplary application illustrated in  FIG. 1 , the aerial ropeway  10  is operated to move objects from one location to another location. In order to move objects, the haul rope cable  30  moves with respect to the support tower  12 . The moving haul rope cable  30  is supported by the plurality of sheaves  16 . 
   With reference to  FIG. 2 , as individual sheave  18  supports the haul rope cable  30 , the sheave  18  rotates about the first axis  20 . In normal operating conditions, the first face  22 , the second face  24  and the track  26  of the sheave  18  support the haul rope cable  30 . Due to a variety of circumstances, the haul rope cable  30  may become misaligned and improperly supported by the sheave  18 . One such misalignment is the separation of the haul rope cable  30  from the track  26 . The cable positioning switch system  50  may sense this misalignment of the haul rope cable  30  and notify the cabinet  180  ( FIG. 7 ). The cabinet  180  may invoke notification and/or take action accordingly. 
   In some circumstances, the proximity sensor  54  of the cable positioning system  50  may be damaged. The proximity sensor  54  may, for example, be damaged by the haul rope cable  30  impacting the proximity sensor  54 . In some circumstances, this damage may cause the proximity sensor  54  to report (via the cable positioning switch system  50 ) to the cabinet  180  the haul rope cable  30  is misaligned. However, in other circumstances, this damage may cause the proximity sensor  54  to incorrectly report that the system is properly positioned (even though the haul rope cable  30  is misaligned). 
   With reference to  FIG. 3 , when the present damage indicator  100  is employed in the previously described situation, the damage to the proximity sensor  54  is reported to the cabinet  180  (via the damage indicator  100 ). As previously described, when the damage indicator  100  receives an impact (for example, an impact from the haul rope cable  30 ), the frangible conductor  170  ( FIG. 6 ) is ruptured. The ruptured frangible conductor  170  is not able to transmit the indicator signal from the first end  172  to the second end  174 . The cabinet  180  may take action(s) to indicate this damage to the proximity sensor  54 . Therefore, use of the present damage indicator  100  improves proper operation of the aerial ropeway  10  by indicating impact to the proximity sensor  54 . 
   In one alternative embodiment, the damage indicator  100  may be provided with crush zones  132  and/or the frangible lines  150  may be formed having varying thickness. In one varying-thickness alternative, the crush zones  132  may be relatively thick near a center of the plate  130  and relatively thin near an outer perimeter of the plate  130 . This alternative allows the frangible conductor  170  to rupture should the impact be from a side rather than directly on top of the damage indicator  100 . 
   In another alternative embodiment, the main body of the damage indicator  100  may be composed of a nonconducting material such as, for example, plastic. In this plastic-damage indicator embodiment, the components (e.g. plate  130 ) may be relatively “invisible” to the proximity sensor  54 . 
   In another alternative embodiment, the damage indicator  100  may be provided with a plate  130  configured as an envelope in which a conductive fluid is retained. The conductive fluid may conduct current in a manner similar to the frangible wire  170 . If the plate  130  (configured with conductive fluid disposed therein) ruptures due to an impact, the sensor signal would not travel through the damage indicator  100 . This non-30 conduction of the sensor signal indicates that the proximity sensor  54  may be damaged. 
   In another alternative embodiment, the damage indicator  100  may be provided with the plate  130  be formed as an air-tight enclosure through which the frangible wire  170  may extend. In this alternative embodiment, the air-tight enclosure may have a vacuum applied thereto. In the event that the plate  130  is ruptured, the vacuum is lost. With a loss in vacuum, air may contact the frangible wire  170 , thereby causing it to rupture. This alternative embodiment is similar to an incandescent light bulb wherein a filament (e.g. tungsten) ruptures if it is exposed to air. 
   While illustrative and presently preferred embodiments have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.