Abstract:
A pressure transducer for a hammer union installation includes a lower body capable of withstanding the stresses of the hammer union installation. The lower body includes a cylindrical wall, a diaphragm, and a pressure port for exposing the diaphragm to pressure. The pressure transducer also includes one or more transducer elements mounted on the diaphragm that are operable to provide a signal related to pressure. A cap is received by the cylindrical wall and is slidable along the wall. The cap includes comprising an antenna for transmitting the signal. A spring is arranged in the lower body for dampening forces applied to the cap.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/892,897, which was filed on Oct. 18, 2013, the contents of which are hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure is directed to ruggedized pressure transducers having integrated wireless communication. More specifically, the present disclosure is directed to high pressure measurement apparatuses, such as hammer union transducers configured to withstand harsher-than-normal physical and/or environmental conditions. Additionally, the present disclosure includes configurations for wirelessly transmitting measurements from within measuring environments. 
     BACKGROUND INFORMATION 
     Certain operations, such as hydraulic fracturing (or “fracking”), cementing, and/or acidizing, require high pressure measurement apparatuses with specialized hammer union transducers. In the case of fracking, a well is typically drilled vertically to a desired depth, then turned approximately ninety degrees to continue horizontally for several thousand feet into the shale believed to contain minerals such as natural gas and oil. A mix of water, sand, and various chemicals may be pumped into the well at high pressure in order to create fissures in the shale through which the gas/oil can escape. Typically, natural gas and oil escape through the fissures and is drawn back up the well to the surface, where it is processed, refined, and shipped to market. 
     As is known in the art, fracking operations are temporary, heavy construction sites, where pressure transducers are mounted in high traffic areas and currently require cables in certain cases to transmit pressure information back to an instrument truck or similar installation. These cables are often damaged during operation, causing disruptions to the operations. Furthermore, the transducers are typically provided in a hammer union (or “wing union”) configuration and may be installed with a sledge hammer, which may cause extreme shock and/or vibration to the transducer. Even glancing blows to the transducer during installation may cause damage, particularly to encasings and/or the underlying circuitry. 
     SUMMARY 
     Accordingly, under one exemplary embodiment, a transducer is disclosed comprising a curved cap assembly, coupled to a lower portion of the transducer, said curved cap assembly comprising an antenna; a spring assembly arranged in the lower portion beneath the cap assembly, said spring assembly being configured to enable dampening of force applied to the curved cap assembly; and a circuit, arranged in the lower portion, said circuit being configured to receive and process data being transduced by the transducer and transmit the processed data to the antenna. 
     Under another exemplary embodiment a transducer is disclosed comprising a curved cap assembly, coupled to a lower portion of the transducer, said curved cap assembly comprising an inductive port and an antenna; a spring assembly arranged in the lower portion beneath the cap assembly, said spring assembly being configured to enable dampening of force applied to the curved cap assembly; a battery, configured in the lower portion; and a circuit, arranged in the lower portion and coupled to the battery, said circuit being configured to (a) receive and process data being transduced by the transducer and transmit the processed data to the antenna, and (b) provide electromagnetic energy received from the inductor to the battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
         FIG. 1A  illustrates an outer perspective view of a ruggedized transducer under one exemplary embodiment; 
         FIG. 1B  illustrates a side cutaway view of the ruggedized transducer of  FIG. 1A ; 
         FIG. 2A  illustrates an outer perspective view of a ruggedized transducer that includes an inductive charging configuration under one exemplary embodiment; 
         FIG. 2B  illustrates a side cutaway view of the ruggedized transducer of  FIG. 2A ; and 
         FIG. 3  illustrates a network system utilizing wireless transducer measurements and/or communications under one exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  illustrates an exemplary embodiment of a ruggedized transducer  100  comprising a lower body  102  and a cap  101 . Cap  101  is preferably produced from a polybutylene terephtalate (PBT) and polycarbonate (PC) blend (PBT/PC), which is compliant with required regulations in the fracking application , although other equivalent materials having relatively high impact resistance may be used as well. For additional strength, other additives, such as an ethylene/N-butyl acrylate/glycidyl methacrylate copolymer (PTW) or Acrylonitrile butadiene styrene (ABS) may be used with the PBT/PC to further strengthen cap  101 . Lower body  102  may be made from a high strength metal suitable for the harsh environment of the fracking operation and capable of withstanding the stresses from the hammer union installation.  FIG. 1B  illustrates a side cutaway view of transducer  200  discussed above in connection with  FIG. 1A . As can be seen from  FIG. 1B , cap  101  may be insertably mated with lower body  102  and preferably held in pace utilizing spring clips  112 . O-ring seal  119  is also preferably used to form an environmental seal between cap  101  and lower body  102  wall. As cap  101  is made from an engineered plastic/polymer, it is suitable for housing an antenna  120  within the internal cap area. In a preferred embodiment, antenna  120  is an omnidirectional antenna in order to transmit or receive radio waves in all directions equally, although other forms of antennas (e.g., directional) may be utilized as well. Antenna  120  is configured to be communicatively coupled to circuit board  116 , via wired or wireless connection, in order to communicate measurements and/or data to/from transducer  100 . 
     For additional protection, at least a portion of the internal cavity of cap  101  is filled with a potting compound  111 . In a preferred embodiment, a cure-in-place potting compound, comprising a low loss, low dielectric material, may be poured over antenna  120 . Potting compound  111  should be a low dielectric material that is substantially non-conductive and in order to minimize interference to antenna operation. Alternately or in addition, foams such as polyisocyanurate and polyurethane pour foams and spray foams have been found to have advantageous non-conductive properties for electronic potting of antennas and have particularly good shock/blast resistance. After potting, the cavity of cap  101  may be enclosed and sealed with a bottom lid as shown in  FIG. 1B  to form a cap enclosure. 
     Cap enclosure  101  may be designed to slide circumferentially into the transducer lower body  102  and is held in place with spring clips  112  and provided with environmental sealing via  0 -ring  119  and may include one or more snap rings. In order to provide advantageous protection against shock, impact and/or vibration, cap enclosure  101  is positioned over a spring apparatus  121  to provide dampening. In the embodiment of  FIG. 1B , the spring apparatus  121  comprises one or more wave springs  118 , where an upper snap ring may be configured to restrain the cap inside the body and a preloaded, high force wave spring holds the cap against the upper snap ring. The preload on the wave spring may be maintained by a lower snap ring. Accordingly, the spring preload and cap are configured to absorb the energy of (accidental) glancing blows from a hammer or other impact/shock experienced during installation. Due to the advantageous shape of the cap, any impact will slide against the force of the spring to absorb the impact of the hammer and allow the hammer to slide over the curved surface of the cap to minimize any damage to the antenna inside. The potting  111  within the cap would provide an additional level of protection. Under a preferred embodiment, it is desirable to keep the profile of the upper transducer and cap as low as possible to reduce the risk of accidental impact by hammers used during the installation process. 
     The transducer lower body of  FIG. 1B  also includes a processing and communications circuit  116  that is preferably embodied as a printed circuit board (PCB). Power for the circuit  116  (as well as antenna  120 ) is provided by battery  117 . In one embodiment, battery  117  may be a conventional IEC-LR6 battery. In another embodiment, battery  117  incorporates Lithium Thionyl Chloride chemistry since it has the highest energy density, longest shelf life, and widest working temperatures that are commercially viable. Battery cells may be assembled into a battery module for greater protection. 
     Circuit board  116  should preferably be IEEE 802.15.4 compliant and comprises a wireless sensor network processing card that includes a power management module and a serial interface module responsible for handling flow control of serial data network data and error correction. Board  116  is preferably controlled by a processor (e.g., ARM Cortex-M3 microprocessor) equipped with an intelligent networking platform that controls transmit/receive packets via a packet queue or memory. Board  116  is also equipped with a wireless communication module that includes RF control for managing ingoing/outgoing communication. It should be understood by those skilled in the art that, while board  116  is described in terms of a printed circuit board, other suitable technologies, such as system on a chip (SoC) or system in package (SiP) may be applied as well without deviating from the spirit and scope of the present disclosure. 
     Similar to the cap enclosure  101 , the bottom of transducer lower portion  102  that contains the circuit board  116 , and even battery  117 , may be encased in a potting compound  113  for additional physical protection. While the lower potting  113  may be similar to potting  111 , care must be taken during an assembly process to ensure that circuit board  116  is not adversely affected during assembly and/or operation. It is possible for circuit board  116  to have elevated heat levels during operation. Therefore, depending on the ultimate application, the potting compound material should not amplify circuit board heating. Preferably, the potting compound material should dissipate the heat; thus thermally conductive potting compounds may be advantageous. Alternately, heat sinks may be employed, in combination with the potting compound, to provide maximum protection while optimizing heat dissipation from the circuitry. 
     During operation, transducer  100  obtains pressure measurements from pressure port  114  via pressure diaphragm  115 . Diaphragm  115  develops compressive and tension stain on the inside surface of the diaphragm which is detected by a strain measuring device, such as a strain gage, can converted to an electrical signal. These measurements are then processed in circuit board  116  and transmitted to antenna  120  for external transmission. In one embodiment, antenna  120  may receive system data and/or data from other transducers and process/forward this data as needed. Further discussion of system communication may be found in the embodiment of  FIG. 3 , below. 
     Turning to  FIG. 2A , another exemplary embodiment is provided wherein transducer  200 , which otherwise is similar to the embodiment of  FIGS. 1A-B , is provided with an inductive charging apparatus for battery  217 .  FIG. 2A  illustrates an exemplary embodiment of a ruggedized transducer  200  comprising a lower body  202  and a cap  201 , just as in  FIG. 1A , except that an inductive charging port  210  is provided in the cap. One advantage of this embodiment is that the user is enabled to recharge the re-chargeable batteries ( 217 ) with an external induction charging system through the polymer cap  201  without disassembling the transducer. The transducer is an intrinsically safe rated device for hazardous locations and disassembly by external parties to replace batteries is not desirable from a safety or liability standpoint. As shown in  FIGS. 2A-B , an inductive port is configured as an indent ( 210 ) in the cap to receive an external induction power source. 
       FIG. 2B  illustrates a side cutaway view of transducer  200  discussed above in connection with  FIG. 2A , and is, unless stated otherwise, identical in configuration and construction relative to  FIG. 1B . Again, cap  201  may be insertably mated with lower body  202  and preferably held in pace utilizing spring clips  212 . O-ring seal  219  is also preferably used to form an environmental seal between cap  201  and lower body  202  wall. Cap  201  houses an antenna  220  within the internal cap area, as well as inductive coil  221 . Inductive coil  221  is operatively coupled to battery  217  in order to enable inductive charging by using electromagnetic fields to transfer energy from a charging device (i.e., inductive power source) inserted into port  210 . Energy is sent through an inductive coupling to a charger, which may be integrated or connected to circuit board  217 , or alternately integrated with battery  217 , which can then use that energy to charge battery  217 . The inductive charging would comprise forming an alternating electromagnetic field from within the inductive power source, which is revived at inductive coil  221  which takes power from the electromagnetic field and converts it back into electrical current to charge battery  217 . In a sense, the two induction coils in proximity through port  210  combine to form an electrical transformer. 
     As in  FIG. 1B , antenna  220  of  FIG. 2B  is preferably an omnidirectional antenna and is configured to be communicatively coupled to circuit board  216 , via wired or wireless connection, in order to communicate measurements and/or data to/from transducer  200 . Again, at least a portion of the internal cavity of cap  201  is filled with a potting compound  211 , similar to potting  111 . Cap enclosure  201  may be designed to slide circumferentially into the transducer lower body  202  and is held in place with spring clips  212  and provided with environmental sealing via O-ring  219  and may include one or more snap rings. In order to provide advantageous protection against shock, impact and/or vibration, cap enclosure  201  is positioned over a spring apparatus  222  to provide dampening, similar to the embodiment of  FIG. 1B . Likewise, the transducer lower body of  FIG. 2B  also includes a processing and communications circuit  216  and battery  217 , encased in potting compound  213 . The configuration of  FIG. 2B  provides the same advantages as those discussed above in  FIG. 1B , and further provides the advantage of enabling convenient battery charging that does not require disassembly of the transducer. 
     Turning to  FIG. 3 , and exemplary embodiment is provided wherein the wireless transmitters having any of the configurations described above are arranged in a wireless network system. Under a preferred embodiment, the transmitters communicate using a WirelessHART protocol, which is a wireless network communications protocol for process automation applications. Under this embodiment, the protocol adds wireless capabilities to the HART Protocol while maintaining compatibility with existing HART devices, commands, and tools that may be used in the system. The WirelessHART standard supports multiple messaging modes including one-way publishing of process and control values, spontaneous notification by exception, ad-hoc request/response, and auto-segmented block transfers of large data sets. These capabilities allow communications to be tailored to application requirements thereby reducing power usage and overhead 
     The system of  FIG. 3  comprises wireless field devices connected to process or plant equipment. In this example, the wireless field devices comprise the ruggedized wireless transducers ( 301 - 305 ) described above in connection with  FIGS. 2A-B  communicating through a WirelessHART-enabled PCB  216  or via a WirelessHART adapter connected to PCB  216 . Transducers  201 - 305  may communicate to one or more access points  307 , as well as with each other. Depending on the configuration needed, transducers  301 - 305  may be arranged in a point-to-point, bus, star, ring, mesh, tree, daisy-chain, or any other suitable network topology. Transducers  301 - 305  may also be configured to communicate with wireless handheld devices  306  as well. 
     Gateway  310  is communicatively coupled to access point  307  and enables communication between communicating devices and host applications  311  connected to a high-speed backbone or other existing plant communications network. Gateway  310  may include (or be separately coupled to) a network manager for configuring the network, scheduling communications between devices, managing message routes, and monitoring network health. The Network Manager can be integrated into the gateway, host application, or process automation controller  312 , and may determine redundant routes based on latency, efficiency and reliability. To ensure the redundant routes remain open and unobstructed, messages may continuously alternate between the redundant paths. Consequently, if a message is unable to reach its destination by one path, it may be automatically re-routed to follow a known-good, redundant path with little to no loss of data. Because these transducers are also used as safety devises, the gateway must also alarm if any transducer ceases to transmit signals. 
     Under a preferred embodiment, the network uses IEEE 802.15.4 compatible radios operating in the 2.4 GHz Industrial, Scientific, and Medical radio band. The radios may employ direct-sequence spread spectrum technology and channel hopping for communication security and reliability, as well as TDMA synchronized, latency-controlled communications between devices on the network. This technology is particularly advantageous in plant installations across a broad range of process control applications. 
     When arranged as a mesh network, each transducer  301 - 305  may serve as a router for messages from other devices. Under this configuration, transducers do not have to communicate directly to gateway  310 , and may forward one or more messages to the next closest transducer. This configuration is advantageous for extending the range of the network and provides redundant communication routes to increase reliability. Furthermore, a mesh configuration eases the process of adding or moving transducers in the network, as long as a transducer is within range of others in the network. 
     While at least one example embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the example embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient and edifying road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention and the legal equivalents thereof.