Abstract:
A break monitoring device for use with a disc coupling having an outermost disc disposed on a disc pack. There is an RFID tag mounted on the outermost disc which transmits a signal to a receiver or monitor. The RFID may be an active or passive tag. When the RFID tag is broken due to the outermost disc failing, the signal sent to the receiver is different than the signal sent during normal operation. This triggers an alert that the outermost disc has failed and the machine can be shut down in an orderly manner.

Description:
BACKGROUND AND SUMMARY OF INVENTION 
       [0001]    This invention relates to disc couplings and more particularly to a device for monitoring when the disc pack begins to fail prior to a system failure. 
         [0002]    Disc couplings are widely used in industrial applications to couple two shafts for the transmission of power from a driving source to a driven piece of machinery. Examples of disc couplings are found in disc couplings manufactured and sold by Lovejoy, Inc. located in Downers Grove Ill. Examples of disc couplings can be found in the Lovejoy, Inc. catalog under the section entitled “Disc Couplings” and are fully illustrated in the catalog. Generally the disc coupling uses two or more hubs and one or more disc packs mounted between the hubs. The disc packs are formed from multiple individual discs. In operation, the portion of the coupling that is prone to failure is the individual discs. Generally, the discs located on the outside of the pack fail before the internal discs fail. Once the disc on the outside of the pack fails, the life of the coupling becomes finite. The time to complete failure can be relatively short, and once the discs begin failing, the remaining discs need to absorb the additional load resulting in their rapid failure. If the failure of the outermost discs is not discovered early in the disc pack failure, the entire disc pack will eventually fail resulting in a system failure and shutdown. 
         [0003]    In the past, in order to inspect the condition of the disc pack, the coupling guards had to be removed and the condition of the disc pack could be examined with a strobe light. This was done with the machine running, which presents a safety hazard as the machine should not be run with the coupling guards removed. Another disadvantage is that this type of inspection required a trained maintenance person to physically do the inspection. This method did not allow for continuous monitoring of the disc pack as the inspection only disclosed the condition of the disc at the moment in time that it is inspected. The disc may be ready to fail in the next few minutes or hours, and the maintenance person has no way of knowing the condition of the disc until the entire coupling failed. 
         [0004]    Another method of disc coupling inspection is to shut down the machine and physically remove and inspect the coupling. This method is expensive as it requires a knowledgeable machine operator to disassemble the coupling, inspect the coupling and then reassemble the coupling. Furthermore this method results in expensive downtime while the machine is not operational. 
         [0005]    Applicant&#39;s invention uses a passive or active radio frequency identification tag (“RFID”) and electrically conductive strip that establishes a circuit around the two outermost discs on either side of a disc pack. If the disc breaks or fractures, the circuit is broken and a transceiver receives a signal that triggers an alert. The machine can be shut down in an orderly process prior to sudden coupling failure and the coupling replaced. 
       OBJECTS AND ADVANTAGES 
       [0006]    It is an object of the invention to provide an early warning system to notify the operator of equipment using a disc pack coupling that the disc pack is prone to fail. 
         [0007]    It is another object to provide a disc coupling break monitoring device that signals the breaking of the outermost disc in a disc pack so that the operator can shut down the equipment in an orderly manner. 
         [0008]    It is another object to provide a disc pack monitoring device that uses an RFID tag that sends a signal to a receiver during normal operation and a different signal when the outermost disc breaks so that an alarm is activated. 
         [0009]    A related advantage of the above objects is that the disc monitoring device operates continuously with the machinery operating and does not require the removal of the safety shields or shut down of the machine in order to examine the disc coupling. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective exploded view of an industrial coupling on which the inventive device can be used. 
           [0011]      FIG. 2  is a perspective view of an alternate embodiment of a disc coupling in which the disc pack is mounted directly to the hub. 
           [0012]      FIG. 3  is a perspective view of the disc pack used in a disc coupling. 
           [0013]      FIG. 4  is a front elevation view of the disc pack. 
           [0014]      FIG. 5  is a cross sectional view of the disc pack taken along line  5 - 5  of  FIG. 4 . 
           [0015]      FIG. 6  is a schematic view of the system illustrating the placement of the RFID tag on the perimeter of the disc and the remote display indicating no failure. 
           [0016]      FIG. 6A  is an enlarged view of the area “A” of  FIG. 6  illustrating the RFID antenna is intact. 
           [0017]      FIG. 7  is a schematic view of the system illustrating the RFID tag in the failed mode with the remote display indicating a failure. 
           [0018]      FIG. 7A  is an enlarged view showing the disc in failure more with the RFID antenna ruptured, with a failed alert being displayed. 
           [0019]      FIG. 8  is an alternate embodiment of a disc pack with the outermost disc having one RFID tag and antenna around the entire disc. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]      FIG. 1  illustrates and describes the basic disc coupling  10 . There are a series of discs  11  that comprise the disc pack  12 . The disc pack  12  is mounted between a pair of hubs  14 . Depending on the particular application, the configuration of the disc coupling varies, but the common feature is that the hubs  14  are separated by and coupled to each other by means of the discs  12 . In the coupling illustrated in  FIG. 1 , which is a coupling sold by Lovejoy, Inc. of Downers Grove, Ill., the illustrated coupling is an Industrial DI Type Coupling. There are two guard rings or anti-flail flanges  16 , each one mounted two one of the hubs  14 . There is a disc pack  12  mounted between a spacer  18  and the anti-flail flange. In the alternate embodiment of  FIG. 2 , the disc pack  12  is mounted directly to and between two hubs  14  and no spacer or anti-flail flanges are used. In either instance, and throughout this application, there is a reference to an outermost disc  13 , which is the exterior disc located on either side of the disc pack  12 . 
         [0021]      FIG. 3  illustrates the disc pack  12  which is attached to the hubs  14  by means of bolts or fasteners  20  and nuts  22 .  FIG. 4  is a front elevation view of the outermost disc  13  contained in the disc pack  12 .  FIG. 5  is a cross section view of the disc pack of  FIG. 4  and illustrates that the disc pack  12  is comprised of a series of individual, thin steel discs  11  stacked adjacent to each other and fastened together by means of the fasteners  20  that pass through mounting holes  21  and secured by nuts  22 . The thickness of the individual discs  11  is dictated by the design of the coupling. 
         [0022]      FIG. 6  illustrates the inventive system and its operation. Radio Frequency Identification, (herein referred to as “RFID”) uses wireless non-contact radio-frequency (“RF”) electromagnetic fields to transfer data from a tag  24  attached to an object, for transmitting information about the object to which it is attached. Some tags require no battery or power source and are powered and read at short ranges (passive tags) and others require a power source and emit RF electromagnetic fields to be read by an RFID reader. The tag  24  contains electronically stored information which may be read from up to several meters away. Unlike a bar code reader, the tag  24  does not need to be within the line of sight of the RFID reader. 
         [0023]    In the preferred embodiment applicant&#39;s invention uses a passive metal mounted tag  24 . The tag  24  is comprised of an integrated circuit (“IC” or “chip”)  26  and a passive tag antenna  28 . Although applicant suggests the use of a passive RFID chip, active chips that use a battery could also be used.  FIG. 6  illustrates the placement of the tags  24  on the outermost discs  13 . As seen in  FIG. 6 , multiple passive RFID tags  24  are placed around the perimeter of the outermost discs  13 . One RFID tag  24  is placed between each of the mounting holes  21 . The tag  24  is generally mounted by means of an appropriate adhesive so that it is securely attached to the disc  13  and will not come off when the disc pack  12  is spinning in normal operation. 
         [0024]    During “Normal” operation, as seen in  FIG. 6 , the power source (not illustrated) drives the driven load through the coupling  10 . The tag antenna  28  is intact as seen in  FIG. 6A  while the disc  13  and coupling  10  are functioning properly. A signal  30  from a transceiver  32  is sent to the tag  24 . A return signal  34  from RFID tag antenna  28  to the transceiver  32  is received, read and interpreted by the transceiver  32  that in turn provides a digital signal to an external device. The external device can be a display, such as display  36 , or an alarm or other similar signaling device. As seen in  FIG. 6 , the display  36  indicates all conditions are “Normal”. 
         [0025]    As seen in  FIG. 7 , when the outermost disc  13  breaks or ruptures, as illustrated by a fracture line  38 , the antenna  28  also breaks or ruptures. The return signal  34  sent by the RFID tag  24  to the transceiver  32  is different than the signal  34  sent when the antenna is unbroken and in the “normal” condition. A comparison of the signal in the normal condition to the signal sent when the antenna  28  is broken, indicates that the antenna  28  was interrupted. The transceiver compares the two signals  34  which indicates that a break in the antenna  28  occurred and sends a signal to the display  36  indicating a “Failed” mode. The display can also be tied into an audio alarm to alert the operator that the outermost disc  13  fractured and the machinery can be immediately shut down or have scheduled maintenance performed as the coupling  10  will still generally operate for a given time except in the most catastrophic situations. Of course the RFID tag  24  can rupture or break anywhere along the RFID tag  24  due to the location of where the outermost disc  13  fails. If the entire tag  24  fails, there will not be any signal transmitted to the transceiver  24 , which will be detected at the transceiver  32  as a failure of the RFID tag  24 . 
         [0026]    In the alternate embodiment illustrated in  FIG. 8 , there is a single RFID tag  24  with the antenna  28  circumscribing the outermost disc  13 . This singular RFID tag  24  replaces the multiple RFID tags illustrated in  FIG. 6 . If any portion of the antenna  28  ruptures, the signal  34  returned to the transceiver  32  will be different than the signal  34  returned when the RFID tag  24  is unbroken. Thus the transceiver  32  will generate an alarm signal. 
         [0027]    Thus, the early warning system indicating that one of the outermost discs  13  has ruptured has achieved the purpose for which it is intended. No longer is visual inspection required to examine the condition of the disc  13  or disc pack  12 . Rather the invention provides continuous monitoring of the outermost disc  13  without the necessity of a skilled maintenance person manually performing the inspection. 
         [0028]    Thus there has been provided a disc coupling break monitoring device that fully satisfies the objects set forth above. While the invention has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.