Abstract:
A process transmitter includes a manually operated power generator to provide electrical power to sense a process variable, produce an output based on the sensed process variable, and provide a display of the output.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to process instruments used in industrial process control systems. More particularly, the present invention relates to a process transmitter having a modular, manually operated power generator. 
   Process transmitters are used to monitor process variables, such as pressure, temperature, flow and level, of process fluids used in industrial processes. For example, process transmitters are widely used in the chemical manufacturing and oil refining industries. Process transmitters are typically employed throughout industrial facilities at multiple locations to monitor a variety of process variables. Additionally, process transmitters are used in isolated field locations such as in cross-country pipelines. 
   Process transmitters include sensors that produce an electrical output in response to physical changes in the process variable. For example, capacitive pressure transducers or piezoresistive pressure transducers produce an electrical output as a function of the pressure of a process fluid. The electrical output of the sensor is processed by the transmitter circuitry so it can be monitored as an indication of pressure of the process fluid. Process transmitters also include electronics for either remotely or locally monitoring the electrical output. Remotely monitored transmitters include electronics that transmit the electrical output over a control loop or network to a central monitoring location such as a control room. Locally monitored transmitters include displays, such as LCD screens, that show the electrical output at the site of the process transmitter. Process transmitters typically draw their power through the control loop or network, or through power delivered through wiring systems typically found in industrial settings. In other embodiments, process transmitters include components for both local and remote monitoring. 
   However, in process transmitters that are located at extremely remote locations, such as on cross-country pipelines or oil and gas wells, it may be impracticable to directly deliver power to the process transmitter through either a control loop or wiring system. Nonetheless, it is necessary to have intermittent process transmitters situated along the pipeline in order to permit direct monitoring of the process fluid at the remote location. 
   Batteries and solar power have been the traditional method of delivering power to remotely located process transmitters. Conventional process transmitters include a terminal block for receiving the wiring associated with the control loop or power wiring systems. The terminal block is located within the housing of the process transmitter and includes terminals for receiving and securing the wires used to deliver the power. Typically the terminals are accessible from the exterior of the process transmitter housing through a conduit opening. The terminal block is connectable with power connectors inside the process transmitter housing that distribute power to the process transmitter electronics and sensor. Terminal blocks are modular and are easily removed from the process transmitter and replaced. A battery or a solar panel can also be coupled to the terminal block. Batteries eventually become fully discharged and therefore can be unreliable in field environments where replacement batteries are not readily available. Also, bringing replacement batteries into the field is burdensome even when they are available. Solar power can also be an unreliable source of energy due to unfavorable weather conditions that does not produce enough light to operate the transmitter. 
   BRIEF SUMMARY OF THE INVENTION 
   A process transmitter includes a sensor, transmitter electronics and a manually operated power generator. The sensor measures a process variable and generates a process variable signal. The transmitter electronics condition the process variable signal. The manually operated power generator supplies power to the sensor and the transmitter electronics. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a partially exploded view of remotely located manual powered process transmitter in which the present invention is used. 
       FIG. 2  shows an exploded view of the process transmitter of  FIG. 1 . 
       FIG. 3  shows a view of the process transmitter having a cap removed and a partially cut away manually operated power generator. 
       FIG. 4  shows a perspective view of another embodiment of a manual powered process transmitter in which the power generator is accessible through an opening in a cap of the process transmitter. 
       FIG. 5  shows another embodiment of a manual powered process transmitter in which a crank handle is connected with a power generator through a conduit opening. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows manual powered process transmitter  10  installed on a remotely situated process fluid source, such as pipeline  12 . Process transmitter  10  is shown with cap  14  removed to show manually operated power generator  16 . Process transmitter  10  includes a sensing apparatus for measuring a process variable such as temperature, pressure, flow and level of the process fluid. Process transmitter  10  includes electronics that convert the output of the sensing apparatus to a format that can be indicated on a display integral with process transmitter  10 , on a handheld field communicator device, or on computer terminals in communication with a control loop. In order for the sensing apparatus and the electronics to operate, it is necessary to provide process transmitter  10  with power. Pipeline  12  is representative of a typical field application of process transmitter  10  in which power is not readily deliverable from a power grid or other such source. Since process transmitter  10  is located at a remote location where external power is not readily available, process transmitter  10  is supplied with manually operated power generator  16 . 
     FIG. 2  shows an exploded view of one embodiment of manual powered process transmitter  10  having manually operated power generator  16  of the present invention. Process transmitter  10  includes cap  14 , manually operated power generator  16 , housing  18 , sensor apparatus  22 , electronics  24 , cap  26 , and connectors  28 . The energy necessary for powering sensor apparatus  22  and electronics  24  is generated by power generator  16 . Power generator  16  includes crank handle  30 , permanent magnet assembly  32  and wire coil assembly  34 . Power generator  16  is a self-contained manually operated power generator that does not require connection to any outside power source. Power generator  16  is modular such that it is easily removed from housing  18  and replaced. Power generator  16  converts mechanical power generated by a human, or another source, to electrical power. In various embodiments of the invention, the manually operated power generator can be operated using cranking, pumping or pedaling action that can convert mechanical energy into electrical energy. In one embodiment, power generator  16  is a DC electromagnetic generator comprised of a permanent magnet and wire winding. 
   In the embodiment shown, sensor apparatus  22  of process transmitter  10  is a pressure sensor. In other embodiments, process transmitter  10  includes a sensor for detecting other process variables such as temperature. Sensor apparatus  22  also provides a support for mounting process transmitter  10  on pipeline  12  (shown in  FIG. 1 ). Located on the underside of sensor apparatus  22  is a hydraulic interface for interacting with the process fluid. Sensor apparatus  22  provides an electrical output that is a function of the process variable as detected through the fluid interface. Sensor apparatus is inserted into the bottom of housing  18  and connected with electronics  24 . 
   Electronics  24  is inserted into housing  18  so that they are linked for communication with sensor apparatus  22 . Electronics  24  is also in communication with connectors  28  so that power can be supplied to electronics  24  when power generator  16  is connected with connectors  28 . Electronics  24  includes circuitry for conditioning the signal generated by sensor apparatus  22  into a functional signal. Also, in one embodiment, electronics  24  include display  36  for visually displaying the signal generated by sensor apparatus  22  and electronics  24 . Display  36  is located on the front side of electronics  24  is visible through cap  26  through glass plate  38 . Cap  26  can be securely tightened down on housing  18 . Additionally, the threads of cap  26  act as quenching channels that prevent internal flames from reaching the outside of process transmitter  10 . 
   In one embodiment, process transmitter  10  includes supercapacitor  42  for storing energy produced by power generator  16 . In a preferred embodiment, supercapacitor  42  is located in power generator  16  such that generator  16  is a complete modular assembly. This makes upgrade of field devices much simpler and also retains the intrinsic safety qualities of electronics  24 . In other embodiments, supercapacitor  42  can be positioned in electronics  24 . Supercapacitor  42  stores a quantity of energy, supplied by generator  16 , from which sensor apparatus  22  and electronics  24  draw current as needed. In one embodiment, supercapacitor  42  is a one farad capacity, and generator  16  provides about six watts of power to supercapacitor  42 . Thus, when energy is produced with generator  16 , supercapacitor  42  stores enough energy to keep sensor apparatus  22  and electronics  24  operating long enough (e.g. up to about five minutes) for information to be obtained from process transmitter  10 . 
   Power generator  16  is inserted into interior storage space  44  of housing  18  and secured to connectors  28 . Connectors  28  provide an interface for supplying power generated by power generator  16  to electronics  24  and sensor apparatus  22 . Connectors  28  can be any suitable means for linking power generator  16  with electronics  24 , such as plugs, prongs, apertures, sockets or the like. Power generator  16  is designed to fit into interior storage space  44  of housing  18  in place of a terminal block that is traditionally found in housing  18 . Connectors  28  are capable of receiving the electrical connectors located on terminal blocks such that process transmitter  10  is able to receive power from a control loop or power wiring system. Power generator  16  is also compatible with connectors  28  such that power generator  16  can supply sensor apparatus  22  and electronics  24  with power through supercapacitor  42 . In the embodiment shown in  FIGS. 1-5 , process transmitter  10  is shown having power generator  16  in lieu of a terminal blocks. 
   Power generator  16  includes foldaway crank handle  30  used to turn permanent magnet assembly (or rotor)  32  inside wire coil assembly (or stator)  34 . When power generator  16  is in the stowed away position, crank handle  30  is folded inside housing  18  and cap  14  is placed over power generator  16  and fastened to housing  18 . A gap is left between power generator  16  and the inside of housing  18  such that rear cap  14  can interface with internal threads of housing  18 . 
     FIG. 3  shows a view of process transmitter  10  having cap  14  removed and partially cut away manually operated power generator  16 . Power generator  16  includes magnetic core assembly  32  and coil winding assembly  34 . Magnetic core assembly  32  includes core housing  50 , magnetic core  52  and crank handle  30 . Coil winding assembly  34  is comprised of winding housing  56  and coil winding  58 . Core housing  50  is partially cut away to show magnetic core  52 . Winding housing  56  is partially cut away to show coil winding  58 . 
   Interior storage space  44  is configured for receiving and encapsulating power generator  16  in lieu of a terminal block. Coil winding assembly  32  is circumferentially smaller than housing  18  to allow for gap  48  to permit rear cap  14  to interface with the threads on the inside of housing  18 . Magnetic core assembly  32  is rotatably fastened to coil winding assembly  34  with pin connection  54 . Crank handle  30  is folded out from magnetic core housing  50  and is in the operable position. Crank handle  30  includes knob  60  that provides a means for grasping and turning core assembly  32 . Core housing  50  also includes recess  62 , which allows crank handle  30  and knob  60  to be tucked away inside power generator  16  in the stowed away position. 
   Power generator  16  is anchored in place to housing  18  by mechanical means such as screws. Magnetic core  52  is any permanent magnet suitable for use in an electromagnetic generator as is known in the art. Coil winding  58  is comprised of a single winding or multiple windings of wire strands, as is known in the art. As magnetic core  52  is rotated, a magnetic field induces a current flow in coil winding  58 . In one embodiment, the current flow is regulated by a voltage regulator and transistors, as is known in the art. The current flows into supercapacitor  42 , whereby it is stored for powering electronics  24 , sensor apparatus  22  and display  36 . 
   Power generator  16  supplies the means for powering sensor apparatus  22  and electronics  24  in order to operate process transmitter  10 . Thus, operation of process transmitter  10  only requires that cap  14  be removed and crank handle  30  be rotated in order to deliver power to supercapacitor  42 ; no external power source is necessary. No special equipment is necessary to supply power to process transmitter  10 . Batteries are not necessary to operate process transmitter  10 . 
   In use, an operator can manually power a process transmitter in a remote location and then record the process measurement, either displayed on the local display or accessed by the operator through a handheld field communicator. Alternatively, the process transmitter could be equipped with a wireless transmitter so that after the operator manually powers up the transmitter, the transmitter can then wirelessly transmit the process measurement to a remotely located control system. 
     FIG. 4  shows a perspective view of another embodiment of manual powered process transmitter  10  in which power generator  16  is accessible through an opening in cap  14 . Power generator  16  is comprised of a coil winding assembly and magnetic core assembly  66 , which is rotatable inside of the coil winding assembly with handle  68 . Cap  14  includes opening  70  to allow access to handle  68  without removing cap  14 . In one embodiment, a barrier, such as an o-ring seal, is positioned between cap  14  and magnetic core assembly  66  in order to provide an environmental seal. 
     FIG. 5  shows another embodiment of manual powered process transmitter  10  in which crank handle  72  is connected with power generator  16  through opening  74 . Opening  74  provides access for wires to a terminal block traditionally located within housing  18 . Opening  74  is configured for receiving conduit containing wires of a control loop or power wires. Crank handle  72  can be connected directly with power generator  16  or with a mechanical system such as a gear train. Crank handle  72  is rotated so as to turn a magnetic core with respect to a coil winding for supplying current to charge a capacitor. 
   Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.