Patent Publication Number: US-2023148404-A1

Title: Cable Gland with Torque Sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 63/263,849, filed Nov. 10, 2021, and which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to a cable gland and more particularly to a cable gland having a torque senor to alert users of the torque being applied to the cable gland. 
     BACKGROUND OF THE DISCLOSURE 
     Cable glands are used for terminating cable in hazardous and nonhazardous environments. More specifically, cable glands generally provide a means for terminating cables, such as unarmored cables (e.g., TC-type) and armored cables, at junction boxes, control centers, panelboards, enclosures, and the like. Typical cable glands are used to seal the junction between a cable and a device and/or an enclosure into which the cable is extending. Referring to  FIG.  1   , conventional cable glands  1  may comprise a hub body  3  for interfacing with the device/enclosure, and a gland nut  5  for securing a bushing  7  to the hub body. The bushing  7  is received in the gland nut  5  and seals around and grips the cable for sealing the interior of the gland from the environment. For example, the bushing  7  may seal around a jacket or outer insulation of the cable. In this configuration, the cable gland  1  comprises two main components. Alternatively, conventional cable glands may comprise a hub body for interfacing with the device/enclosure, a union body/sleeve received in the hub body, and a gland nut for securing the union body to the hub body. Therefore, in this configuration, the cable gland comprises three main components. 
     Cable glands can be used with a range of cable diameters. A contact pressure will vary depending on the size of the cable. In practice, it is recommended to have a contact pressure between the cable and the gland of more than 2 MPa to avoid water ingress. However, in some instances a contact pressure in conventional cable glands can reach up to 15 MPa. Such a high contact pressure may damage the cable jacket causing water ingress after high temperature conditioning/aging. The high contact pressure as a result of over-torqueing the cable gland components may also cause damage to the cable gland threads and sealing elements. 
     SUMMARY 
     In one aspect, a cable gland generally comprises a hub body having a first end configured for attachment to a structure and a second end opposite the first end. The hub body defines an internal passage. A gland nut is configured for attachment to the second end of the hub body to secure a cable in the cable gland. The gland nut defines an internal passage such that the internal passage of the gland nut communicates with the internal passage of the hub body when the gland nut is attached to the hub body. A torque sensor module is mounted to one of the hub body and the gland nut and configured for measuring and indicating a component of an applied torque as a result of attaching the gland nut to the hub body when securing the cable in the cable gland. 
     In another aspect, a torque sensor module for a cable gland generally comprises a contact configured to measure a physical input from attaching a gland nut of the cable gland to a hub body of the cable gland. A sensor element is in electrical communication with the contact for receiving the measured physical input at the contact and converting the physical input into an electrical output indicating a component of an applied torque as a result of attaching the gland nut to the hub body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is cross section of a cable gland of the prior art; 
         FIG.  2    is an exploded view of a cable gland of the present disclosure; 
         FIG.  3    is a fragmentary longitudinal section of the cable gland in  FIG.  2   ; 
         FIG.  4    is a circuit diagram of a torque sensor module; 
         FIG.  5    is a chart illustrating standard torque values for a given gland size; 
         FIG.  6    is a fragmentary perspective of a hub body of the cable gland showing a torque sensor module in a first orientation; and 
         FIG.  7    is a cross section of the hub body showing torque sensor modules in a second orientation. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The cable gland described herein has features that, when tightening the components of the cable gland, provide a measurement of the torque being applied to the cable gland and indicate that torque to the user. As such, the user is alerted as to when sufficient torque has been applied to the cable gland to prevent an under or over-torqueing condition from occurring. Therefore, the assembled cable gland provides a secure connection between the components of the cable gland, and between the cable gland and the cable. However, the connection forces between the cable gland components and the cable do not exceed predetermined thresholds which might cause damage to one or both of the cable gland and cable. Additionally, proper electrical contact between the cable and a grounding mechanism of the cable gland is facilitated without extruding the bushing from a gland nut because the proper amount of torque for the gland is communicated to the user. In the illustrated embodiment described below, the cable gland assembly comprises a three-piece design. However, the features of the present disclosure are applicable to cable glands having a two-piece gland design or some other gland design, without departing from the scope of the disclosure. 
     In the below examples, the cable gland has at least one torque sensor module mounted to a hub body of the cable gland. By measuring components of the torque experienced by the hub body, the amount of torque applied to the cable gland, and subsequently to the cable in the cable gland can be monitored. This enables the user to apply the exact or substantially close to the exact right amount of torque for the cable gland to function as intended. Therefore, a condition in which the cable gland is over-torqued can be identified and/or prevented. As a result, quality control can be implemented across different users of the cable gland. Moreover, the torque applied to the cable gland can be indicated without the use of any additional tools such as a torque-sensing wrench. Thus, the cable gland is in itself equipped to both measure the applied torque and indicate that torque to the user. 
     Many components of the cable gland may be referred to as having generally cylindrically, circular, annular, or conical features, and as having cylindrical or circular holes, cavities, and openings. Such features may be referred to, or defined by, a circumference, radius, external surface, internal surface, and/or other terms appropriate for defining such features. It should be noted that such features may alternatively be elliptical, polygonal, and the like. As used herein, the terms “axial” and “longitudinal” refer to directions and orientations, which extend substantially parallel to a centerline of the cable gland. Moreover, the terms “radial” and “radially” refer to directions and orientations, which extend substantially perpendicular to the centerline of the cable gland assembly. In addition, as used herein, the terms “circumferential” and “circumferentially” refer to directions and orientations, which extend arcuately about the centerline of the cable gland assembly. 
     Referring to  FIGS.  2  and  3   , an illustrated embodiment of a cable gland constructed according to the teachings of the present disclosure is generally indicated at reference numeral  10 . In general, the cable gland  10  is configured to seal the junction between a cable and a device and/or an enclosure into which the cable is extending. As explained in more detail below, the cable gland  10  includes a sensor that measures and indicates a torque applied to the cable gland. As a result, the cable gland  10  is equipped to alert the user of the torque that has been applied to the gland to prompt the user to adjust the amount of torque as needed to apply a desired amount of torque. For example, a preset range of acceptable torque amount can be programmed into the sensor to alert the user when the torque applied to the cable gland  10  is outside of the preset range. The other components of the cable gland  10 , also described below, are illustrative and may be of other designs or constructions. 
     In general, the cable gland  10  includes a hub body, generally indicated at reference numeral  12 , and a gland nut, generally indicated at reference numeral  14 . Together, the hub body  12  and the gland nut  14  define a gland body. The hub body  12  has a first end with external connection thread(s)  16  for threading into a device, an enclosure, or other structure, and a second end with an external nut thread  18  for threadably mating with the gland nut  14 . The first end of the hub body  12  may be coupled to a cable termination assembly (not shown), such as a junction box, control center, panelboard, enclosure, and the like. 
     An internal passage  19  extends through the first and second ends of the hub body  12  and is configured to receive a portion of a cable inserted into the cable gland  10 . The hub body  12  may comprise or be formed from, for example, a metal, such as aluminum, stainless steel, and/or brass. A face seal  20  and a locknut  22  may be received on the first end of the hub body  20 . As installed, the face seal  20  is sandwiched between an exterior face of the device, enclosure, or other structure and a tool coupling portion  24  (e.g., a hexagonal or other polygonal structure) to create the watertight seal and inhibit ingress of water, oil, and/or other debris into the device, enclosure, or other structure. The face seal  20  may comprise or be formed from, for example, silicone, such as a silicone rubber having a durometer of 70 Shore A Hardness. The locknut  22  is threaded on the connection thread  16  within the device, enclosure, or other structure and contacts the interior face of the device, enclosure, or other structure to lock the cable gland  10  to the device, enclosure, or other structure. The locknut  22  may comprise or be formed from, for example, a metal, such as aluminum, stainless steel, and/or brass. In one or more embodiments, the face seal  20  and/or the locknut  22  may be omitted. An armor stop  28  and an annular grounding spring  30  (e.g., garter spring) are received in the passage of the hub body  12 , such as at the second end thereof. The armor stop  28  limits the insertion of cable armor of the cable in the cable gland  10 . The armor stop  28  may comprise or be formed from, for example, plastic, such as a polyamide (e.g., nylon or nylon 6/6). The grounding spring  30  engages and surrounds the cable armor to create a grounding connection. The grounding spring  30  may comprise or be formed from, for example, metal, such as stainless steel with copper flash coating. The armor stop  28  and the grounding spring  30  may be of other designs and configurations. 
     The gland nut  14  has an internal passage  31  extending through first and second ends of the gland nut. The internal passages  31 ,  19  of the gland nut  14  and the hub body  12  are generally alignable with one another to form an internal passage of the gland body that is configured to receive the cable. The first end of the gland nut  14  includes an internal thread(s) (not shown) configured to threadably mate with the external nut thread  18 , as shown in  FIG.  2   . The gland nut  14  may comprise or be formed from, for example, a metal, such as aluminum, stainless steel, and/or brass. By coupling the gland nut  14  to the hub body  12  through a threaded connection, to tighten the gland nut on the hub body, the gland nut can be rotated about a longitudinal axis LA and with respect to the hub body. The tightening of the gland nut  14  on the hub body  12  secures the cable within the cable gland assembly  10  and also establishes a ground path through the cable gland. Additionally, this connection assembly enables the gland nut  14  to be completely removed from the hub body  12  as required or desired. 
     A sleeve  38 , a bushing  40 , and a washer  42  are received in the internal passage of the gland nut  14 . The bushing  40  is disposed between the sleeve  38  and the washer  42 . The bushing  40  comprises a bushing body  50  having a generally annular shape with an interior surface defining a bushing opening  52  extending through first and second ends of the bushing body along an axis of the bushing body. The bushing opening  52  is generally aligned with the internal passage of the gland nut  14  and is configured to receive the cable therein. 
     When the cable gland  10  is assembled, the sleeve  38  is disposed between and engages the spring  30  and the bushing  40 . The sleeve  38  guides compression of the bushing  40 , and compression of the spring  30 . This compression around the cable provides a retaining force on the cable to prevenient cable pull out and to enable a secure cable gland  10  and cable connection. Additionally, the bushing  40  facilitates a watertight seal on the outer jacket of the cable to reduce or prevent water penetration into the cable gland  10 . The sleeve  38  may comprise or be formed from, for example, plastic or metal, such as aluminum, stainless steel, and/or brass. The washer  42  is disposed between the bushing  40  and a shoulder  44  of the gland nut  14  at the second end of the gland nut. The washer  42  distributes the load applied by the shoulder  44  of the gland nut when the cable gland  10  is assembled. The washer  42  is also configured to enable the gland nut  14  to rotate relative to the bushing  40  so that the bushing does not buckle during rotation of the gland nut. In other examples, grease may be used to reduce or prevent bucking of the bushing  40 . The washer  42  may comprise or be formed, for example, plastic, such as a polyamide (e.g., nylon or nylon 6/6). 
     The gland nut  14  and the hub body  12  each include a central opening and are coupled together concentrically such that a cable path traverses the cable gland  10  along the longitudinal axis LA of the cable gland. A cable (not shown) may be disposed and/or terminated inside the cable path. As described herein, the cable may be an armored cable that includes an outer jacket layer, an armor layer, and at least one conductor. The cable may alternatively be an unarmored cable that includes an outer jacket layer, an insulation layer, and at least one conductor. It should also be appreciated that the cable gland  10  may be used with any other cable layer configuration that enables the assembly to function as described herein. 
     In operation, the cable gland  10  is configured such that the cable may be retained by tightening the gland nut  14  (e.g., rotating about the longitudinal axis LA) about the hub body  12 . When the gland nut  102  is first tightened, a torque load is applied to the cable gland  10  and the grounding spring  30  axially and radially displaces, and compresses around the cable armor, while the bushing  40  remains relatively uncompressed. Once the grounding spring  30  reaches the cable armor (for armored cable types), its compression stops or slows down and at least a portion of the torque load is directed towards the bushing  40 . As the torque load is applied to the bushing  40 , the bushing is displaced and compresses around the cable jacket. During the compression of the bushing  40 , the grounding spring  30  may continue to receive some torque load and further compress a small or no amount. 
     Referring to  FIGS.  3  and  4   , a torque sensor module  60  is mounted on the gland body (i.e., hub body  12  or gland nut  14 ) and is configured to measure and provide an indication of an amount of torque being applied to the cable gland  10  as a result of the gland nut  14  being tightened around the hub body  12  to secure the cable in the cable gland. The torque sensor module  60  comprises an electrical circuit including a contact  62  positioned on the gland body to measure a physical input from the tightening of the gland nut  14  onto the hub body  12 , and a sensor element  64  in electrical communication with the contact for receiving the measured physical input at the contact and converting the physical input into an electrical output. In particular, the act of tightening the cable gland  10  may cause a physical displacement of elements of the contact  62  which is sensed by the sensor element  64  and represented by a corresponding voltage output. In one embodiment, the sensor element  64  comprises a transducer (i.e., piezoelectric sensor) configured to convert the physical input into a voltage output. The sensor element  64  may produce a linear response to the torque applied to the cable gland  10  such that the amount of displacement is recorded as a corresponding linear increase in voltage. The circuit further comprises an indicator  66  and a switch  68  disposed between the sensor element  64  and the indicator. In the illustrated embodiment, the indicator  66  comprises one of more lights (e.g., LEDs). However, the indicator  66  could comprises any suitable element for providing a visual, audio, and/or tactile indication without departing from the scope of the disclosure. 
     When the switch  68  is closed, the sensor element  64  can record the physical displacement of the contact elements and produce a voltage output which is analyzed by the sensor module  60 . The sensor module may be configured such that the circuit will activate the indicator  66  when the recorded voltage output is outside of a predetermined voltage range and/or above or below a threshold voltage. For example, the cable gland  10  may be constructed to operate at a predetermined torque range/threshold to ensure that the components are securely fastened without damaging the cable gland or the cable within the cable gland. Therefore, the sensor module  60  can be programmed to activate the indicator  66  if the voltage output corresponding to the applied torque is outside of or deviates from the predetermined torque range/threshold for the cable gland  10 . It will be understood that the size, configuration, and utility of the cable gland will impact the optimal torque range/threshold. As such, the sensor module  60  will be configured for the specific cable gland with which it is used. For example,  FIG.  5    shows a chart indicating one embodiment of standard torque values for a given gland size. The torque values may be analogous to the voltage thresholds stored in the sensor module  60 . As such ranges within a given tolerance of the toque values may be similarly stored in the sensor module  60 . It will be understood that other torque values may be utilized without departing from the scope of the disclosure. 
     Referring to  FIG.  6   , a plurality of sensor modules  60  are mounted to the hub body  12  in a first configuration. An interior space  70  in the hub body  12  houses one or more of the sensor modules  60 . The sensor modules  60  are spaced circumferentially around the hub body  12  and extend generally radially such that the modules are configured to measure the force vector of the torque applied to the cable gland in an axial direction. In particular, the sensor modules  60  are arranged to measure the axial component of the reactive force arising due to the applied torque to the cable gland  10 . This configuration may be particularly useful in cable glands which involve considerable axial movement of the gland nut  14  compared to the radial movement of the sleeve  38  inside the gland body. In the illustrated embodiment, the sensor modules  60  are shown disposed in the interior space  70  of the hub body  12 . However, the sensor modules  60  could be disposed at other locations without departing from the scope of the disclosure. For instance, the sensor modules  60  could be located on an interior surface of the hub body  12  such that the modules are disposed between the hub body and the cable when the cable is received in the cable gland  10 . Alternatively, the sensor modules  60  could be disposed on or in the gland nut  14 . For example, the sensor modules  60  may be disposed between the gland nut  14  and the hub body  12 , between the gland nut and the sleeve  38 , or between the gland nut and the washer  42 . Referring to  FIG.  3   , the sensor modules  60  may also be located between the sleeve  38  and bushing  40 . This location may also be particularly useful for measuring the axial component of the reactive force arising due to the applied torque to the cable gland  10 . Still other locations are envisioned. 
     Referring to  FIG.  7   , a plurality of sensor modules  60  are mounted to the hub body  12  in a second configuration. The sensor modules  60  are spaced circumferentially around the hub body  12  and extend generally circumferentially such that the modules are configured to measure the force vector of the torque applied to the cable gland  10  in the radial direction. In particular, the sensor modules  60  are arranged to measure the radial component of the reactive force arising due to the applied torque to the cable gland  10 . An engagement between the hub body  12  and a cable C received in the hub body is also shown in  FIG.  7   . The ability of the sensor modules  60  to measure the radial component of the torque applied to the cable gland is schematically represented by the springs which are compressible in the radial direction. This configuration may be particularly useful in cable glands which involve considerable radial movement of the sleeve  38  inside the gland body compared to the axial movement of gland nut  14 . In the illustrated embodiment, the sensor modules  60  are shown disposed in the hub body  12 . However, the sensor modules  60  could be disposed at other locations without departing from the scope of the disclosure. For instance, the sensor modules  60  could be located on an interior surface of the hub body  12 . Referring to  FIG.  3   , the sensor modules  60  may also be located next to the spring  30  or utilized in replacement of the spring. This location may also be particularly useful for measuring the radial component of the reactive force arising due to the applied torque to the cable gland  10 . Alternatively, the sensor modules  60  could be disposed on or in the gland nut  14 . For example, the sensor modules  60  may be disposed between the gland nut  14  and the hub body  12 , between the gland nut and the sleeve  38 , or between the gland nut and the washer  42 . Still other locations are envisioned. 
     In one embodiment, the sensor modules  60  can be wirelessly connected to a remote hub for communicating the torque data to the hub. For instance, sensor module  60  may include or be operatively connected to a transmitter for sending the torque date to the hub. Thus, the amount of torque applied and any instances of under-torqueing or over-torqueing can be recorded by the remote hub. 
     Modifications and variations of the disclosed embodiments are possible without departing from the scope of the invention defined in the appended claims. 
     When introducing elements of the present invention or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As various changes could be made in the above constructions, products, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.