With Pick-up Coil Patents (Class 73/861.78)
  • Patent number: 10214980
    Abstract: A sensor assembly may include a housing made of a non-magnetic material. The housing may define an interior chamber. A shaft may extend from the housing. A bearing may be positioned around the shaft. An impeller may be positioned around the shaft and the bearing, and the impeller may include a magnetized portion. A sensor may be positioned within the interior chamber and/or proximate the magnetized portion. The sensor may detect the magnetized portion of the impeller to sense a rate of rotation of the impeller. The rate of rotation of the impeller may correspond to changes in flow rate of the fluid. As the flow rate of the fluid, and the rate of rotation of the impeller change in predetermined manners, control signals may be conveyed to activate a tool.
    Type: Grant
    Filed: June 17, 2015
    Date of Patent: February 26, 2019
    Assignee: SCHLUMBERGER TECHNOLOGY CORPORATION
    Inventors: Jacques Orban, R. Craig Boswell, Scott Richard Woolston, Jordan Dane Englund
  • Patent number: 10012072
    Abstract: A flow meter for measuring multi-phase flow and method of use comprising an impeller assembly having a one or more blades in an asymmetric blade configuration on a rotational shaft and one or more sensors to measure partial rotations of the blades. Sensors may obtain impeller rotational information associated with various portions of the flow stream. With this multi-phase fluid flow may be determined from the determined local velocity information, the operation of a fluid-flow system may be enhanced.
    Type: Grant
    Filed: January 17, 2013
    Date of Patent: July 3, 2018
    Assignee: ExxonMobil Upstream Research Company
    Inventor: Pietro Valsecchi
  • Patent number: 9651401
    Abstract: A sensor and a method for detecting objects using an inductive sensor. An electrical alternating field is generated by using an oscillating circuit, wherein the amplitude and/or frequency of a signal of the oscillating circuit changes when an object is present. The signal of the oscillating circuit is rectified. The rectified signal is relayed to a high-pass filter, wherein damping of the oscillating circuit caused by nonmoving objects is filtered by the high-pass filter. The signal is compared with a threshold value, and an output signal is generated when the signal value is above or below the threshold value.
    Type: Grant
    Filed: June 26, 2009
    Date of Patent: May 16, 2017
    Assignee: Rechner Industrie-Elektronik GmbH
    Inventor: Armin Kohler
  • Publication number: 20150135852
    Abstract: Battery-free meter for flowing media, in which a rotor body (sleeve 4) which is fitted with permanent magnets (6, 7) and is driven in a rotary fashion by the medium is arranged in the pipeline (34) carrying the flowing medium (8) and in which the rotating magnetic field generated by this acts on at least one Wiegand sensor (25, 26), which is arranged outside the flowing medium in the area around the meter, wherein a housing part (15) which is open on at least one side sealing to the interior of the pipeline (34) engages with the pipeline (34) and around which the flowing medium at least partially flows, such that the external periphery of the housing part (15) is at least partially embraced by the rotor part (sleeve 4) which is driven in a rotary fashion and generates the rotating magnetic field and that at least one Wiegand sensor (25, 26) is arranged in the housing part (15).
    Type: Application
    Filed: April 25, 2013
    Publication date: May 21, 2015
    Applicant: Hengstler GmbH
    Inventors: George Efimov, Michael Mixner
  • Publication number: 20150059466
    Abstract: A hydration monitoring device and system for recording and controlling an individual's hydration includes an improved fluid flow sensor configured to measure a quantity of fluid transferring from a reservoir to a user in a first fluid flow direction only.
    Type: Application
    Filed: August 30, 2013
    Publication date: March 5, 2015
    Applicant: ATP, Inc.
    Inventor: Daniel Todd Adlon
  • Patent number: 8866634
    Abstract: A meter that monitors usage of a water distribution system by a client is provided. The meter includes a wireless communications system operable to communicatively couple the meter to a wireless network to provide two-way communication between the meter and the wireless network; a calibration system operable to calibrate the meter, wherein the calibration system may calibrate the meter in response to an instruction received via the wireless network; and a power system operable to maintain a sufficient level of power for the meter to allow substantially real-time communication between the meter and the wireless network.
    Type: Grant
    Filed: May 4, 2007
    Date of Patent: October 21, 2014
    Assignee: Capstone Metering LLC
    Inventors: Walter Scott Williamson, James Scott Williamson, Jack Ryan Williamson
  • Patent number: 8839681
    Abstract: A system and method for monitoring inefficient flow rates in a liquid-flow distribution system, such as that which is used in agricultural liquid application equipment. This may include blockages or punctures in a liquid line. The system generally includes a plurality of gauges for monitoring the supply line flow rate in a liquid application system which are monitored by a number of sensors. Immediate feedback is presented to the operator of the vehicle inside the cab. The system alerts the operator when a blockage, loss, or increase of flow rate has occurred in one of the liquid lines. The system may merely indicate that one of the lines is blocked, or the system may be more sophisticated such that it can indicate which line is blocked and adjust the flow in that line in an attempt to clear the blockage.
    Type: Grant
    Filed: July 12, 2013
    Date of Patent: September 23, 2014
    Assignee: CDS-John Blue Company
    Inventors: Jason T. Stewart, Bradley R. Thurow, David C. Batcheller, Robert M. Allen, Steven S. Bailey, Christopher L. Giese
  • Publication number: 20140144249
    Abstract: The invention relates to a method for measuring the volumetric flow (Q) of a fluid in a preferred direction by means of a volume measurement device having an electronic circuit and an incremental encoder, a sensor for detecting a rotational change of angle, preferably designed as two giant magnetoresistance (GMR) sensors in a double measuring bridge, wherein a first sinusoidal signal of the incremental encoder, namely a raw sine signal (S1), and a second sinusoidal signal of the incremental encoder with identical angular frequency ? which is phase-shifted by 90° relative to the first signal (S1), namely a raw cosine signal (S1), are generated, wherein said signals (S1) are preferably initially conditioned (S1+), interpolated/digitized (S2), and said digital signals (S2) are processed and evaluated in an evaluation unit, preferably in a process computer unit having a quadrature encoder counter.
    Type: Application
    Filed: November 8, 2011
    Publication date: May 29, 2014
    Applicant: VSE VOLUMENTECHNIK GMBH
    Inventor: Jorg Kirchertz
  • Publication number: 20130036834
    Abstract: An adapter assembly that works with a standard utility meter to wirelessly transmit data about consumption. The adapter assembly generates information about consumption by cooperating with a pointer or shaft of an index (or index bracket) of a utility meter. In some versions, the adapter assembly includes an upper portion and a lower portion that interface together. The upper portion and the lower portion are configured to maintain alignment with the pointer/shaft and not create stress on the index.
    Type: Application
    Filed: August 9, 2011
    Publication date: February 14, 2013
    Applicant: Cellnet Innovations, Inc.
    Inventors: Louay Ibrahim Abdul-Hadi, Nathan Edward Woody
  • Patent number: 8279080
    Abstract: A remote water meter monitoring system is provided. A mesh network-type transceiver unit is coupled to a water meter housing having a water counting mechanism inside to transmit water consumption information as well as other sensor information, such as backflow detection, water pressure, and water metrics (e.g., residual chlorine and temperature) to a central server system via a bridge device and a corresponding mesh network. Mechanical energy from the water flowing through the water meter housing is converted to electrical energy via an energy conversion unit. An electrically powered shut off valve is remote addressable via the transceiver unit.
    Type: Grant
    Filed: June 8, 2007
    Date of Patent: October 2, 2012
    Assignee: Fairfax County Water Authority
    Inventors: Barth Robins Pitchford, William Dudley Pitchford, Robert Paul Simon, C. David Binning, David Lewis Rasmussen
  • Publication number: 20120227511
    Abstract: An adapter assembly that works with a standard utility meter to wirelessly transmit data about consumption. The adapter assembly generates information about consumption by cooperating with a pointer of an index of a utility meter. In some embodiments, the adapter assembly includes an upper portion and a clip that interface together. The upper portion and the clip are configured to maintain alignment with the pointer and not create stress on the index.
    Type: Application
    Filed: March 8, 2011
    Publication date: September 13, 2012
    Applicant: Cellnet Innovations, Inc.
    Inventors: Michael B. Davis, Nathan Edward Woody
  • Patent number: 8205509
    Abstract: A flow meter for measuring the velocity of surrounding fluid, comprising a rotatable member rotatably coupled to a shaft member, wherein the shaft member comprises a measuring electrical circuit comprising an AC power supply and a primary coil, the rotatable member comprising a passive non-permanent magnet marker responsive to a magnetic field, the arrangement being such that when the circuit is powered by the AC supply the coil generates a magnetic field and the marker is positioned on the rotatable member such that rotation of the rotatable member in response to fluid drag on the member causes the distance between the marker and the coil to oscillate, the marker interacting with the magnetic field at its closest approach to the coil, thereby to cause a measurable electrical response in the circuit.
    Type: Grant
    Filed: November 2, 2009
    Date of Patent: June 26, 2012
    Assignee: Shlumberger Technology Corporation
    Inventor: Gary Oddie
  • Patent number: 7980143
    Abstract: An apparatus for use with a liquid supply pipeline, for transforming energy of liquid passing therethrough into electrical energy, comprising: a housing configured to be received within the pipeline and having a liquid inlet and a liquid outlet defining a flow direction therebetween, at least one current generator including a rotor supported by the housing and having a shaft and a plurality of vanes attached thereto, the shaft extending in the housing along the flow direction allowing rotation of the vanes by liquid passing through the generator, and a stator associated with the rotor for producing electrical signals corresponding to the rotation of the rotor, and a power storage mean to which the at least one current generator is electrically connected, for receiving the electrical signals.
    Type: Grant
    Filed: March 23, 2010
    Date of Patent: July 19, 2011
    Assignee: Hydrospin Monitoring Solutions Ltd
    Inventor: Dani Peleg
  • Patent number: 7975560
    Abstract: A magnetic shield may be mounted to a water meter housing to protect the magnetic operation of the water meter from a tamper magnet, including both smaller, flexible tamper magnets and larger, strong tamper magnets. The shield may include a contoured portion and a barrier portion. The barrier portion may provide a physical and spatial barrier between a larger tamper magnet and an internal magnetic sensor of the water meter. The contoured portion may conform to the housing of the water meter and may prevent smaller tamper magnets from being maneuvered close to the housing of the water meter. The shield may be made of a ferrous material suitable for attenuating a magnetic field. The shield may receive a looped sensor transmission cable within a U-shaped opening enabling the shield to be installed and/or removed from the water meter without the sensor transmission cable being detached from the water meter.
    Type: Grant
    Filed: August 25, 2008
    Date of Patent: July 12, 2011
    Assignee: Elster Amco Water
    Inventors: Rolando Armas, Evan Hengge
  • Patent number: 7886616
    Abstract: An in-line flow meter assembly for insertion into a pipe section, including a body comprising an elongate tubular section having a cavity; a turbine assembly support extending a determined distance from the body; a turbine shaft attached or coupled to the turbine shaft connection portion; a turbine element having a plurality of rotor blades extending radially from a central hub of the turbine element; a bearing positioned on the shaft and press fit into a hub of the turbine element; a pickup coil that is able to sense rotational motion of the turbine element and convert the rotational motion into a pulsing electrical signal; a riser having a height such that when the riser is attached or coupled to the pipe section, a rotational axis of the turbine element is located in a cross sectional center of the pipe section, regardless of a diameter of the pipe section.
    Type: Grant
    Filed: November 17, 2009
    Date of Patent: February 15, 2011
    Assignee: Hoffer Flow Controls, Inc.
    Inventor: Robert W. Hayman
  • Publication number: 20090107253
    Abstract: A magnetic shield may be mounted to a water meter housing to protect the magnetic operation of the water meter from a tamper magnet, including both smaller, flexible tamper magnets and larger, strong tamper magnets. The shield may include a contoured portion and a barrier portion. The barrier portion may provide a physical and spatial barrier between a larger tamper magnet and an internal magnetic sensor of the water meter. The contoured portion may conform to the housing of the water meter and may prevent smaller tamper magnets from being maneuvered close to the housing of the water meter. The shield may be made of a ferrous material suitable for attenuating a magnetic field. The shield may receive a looped sensor transmission cable within a U-shaped opening enabling the shield to be installed and/or removed from the water meter without the sensor transmission cable being detached from the water meter.
    Type: Application
    Filed: August 25, 2008
    Publication date: April 30, 2009
    Applicant: ELSTER AMCO WATER
    Inventors: Rolando Armas, Evan Hengge
  • Patent number: 7245230
    Abstract: The present inventions relate to a method and apparatus for adding Automatic Meter Reading (AMR) capabilities to utility meters that generate a magnetic field comprising magnetic flux that varies proportionally with the rate of resource consumption. The apparatus comprises a dual magnetic field sensor unit for detecting variations in the magnetic flux density for the magnetic field. The sensor unit may be compact in size so that it can be positioned within a utility meter. The sensor unit may be operatively connected to a data-unit located outside the utility meter. The data unit may be further configured for storing processed or unprocessed sensor signals and is connected to a transmitter. To minimize power consumption, the magnetic field sensors may be configured to have sensor on times and sensor off times. The on/off state of the magnetic field sensors may be controlled by either a dedicated sensor controller or the data unit.
    Type: Grant
    Filed: February 11, 2005
    Date of Patent: July 17, 2007
    Assignee: MARS Company
    Inventors: Floyd Stanley Salser, Jr., Ian Phillip Harvey, Roger Allcorn
  • Patent number: 7106054
    Abstract: A device for sensing the rotation of a member rotating about an axis XX? comprises m proximity sensors situated in a plane perpendicular to the axis XX? and in m radial directions, m being an integer greater than or equal to 2. A mark fastened to the rotary member and eccentric to the axis XX? modifies the amplitude response of the proximity sensors when the rotary member rotates. An excitation circuit excites the proximity sensors, each sensor supplying an excitation response when it is excited. The amplitude of the excitation response of each of the sensors is compared with a comparison threshold value during a time period referred to as an observation window to supply a logic level 1 or 0 according to whether the response amplitude is greater than or less than the comparison threshold value. The movement of the mark past one of the sensors is identified as a function of the value 0 or 1 of said logic level.
    Type: Grant
    Filed: December 22, 2004
    Date of Patent: September 12, 2006
    Assignee: Actans SAS
    Inventors: Hervé Dury, Serge Bulteau, Eric Michaud
  • Patent number: 7007558
    Abstract: A pulse transmitter for fluid metering includes concentric gearing, with the exciter gear concentric with the main shaft in the center. Because of this concentricity, one can put practically any number of additional coils (typically four) to get four or more outputs. Also, each coil could be dual output to get eight outputs from four coils. Each coil preferably produces 1000 pulses per revolution of the main shaft. Because of its compactness and light weight, this pulse transmitter has a more practical application in the liquid metering industry than prior transmitters.
    Type: Grant
    Filed: May 27, 2003
    Date of Patent: March 7, 2006
    Assignee: Lake Charles Instruments, Inc.
    Inventor: Frank Carpenter
  • Patent number: 6886414
    Abstract: Flow device for generating electrical power from fluid flow. The device comprises rotatable structure driven by the fluid, which in turn drives a magnetic field generator. A magnetic sensor responsive to the magnetic field generates electrical power for powering external devices.
    Type: Grant
    Filed: April 21, 2003
    Date of Patent: May 3, 2005
    Assignee: Dresser, Inc.
    Inventors: Francisco M. Gutierrez, Rick D. Atton
  • Patent number: 6881507
    Abstract: The mass flow of hydrogen fuel in the anode loop of a hydrogen fuel cell is measured using a rotating flow meter. The flow meter includes a bladed rotor mounted for rotation within a tube disposed in the stream of hydrogen fuel flowing through the anode loop. A magnetic sensor senses changing magnetic field caused by the rotation of the rotor and produces an alternating signal having a frequency related to the rotational rate of the rotor, and thus of the mass flow rate of the hydrogen fuel. A fuel purity sensor increases the accuracy of the mass flow measurement by determining the concentration of foreign substances contained in the fuel.
    Type: Grant
    Filed: June 4, 2003
    Date of Patent: April 19, 2005
    Inventor: Milos Milacic
  • Patent number: 6850054
    Abstract: A device and a method for non-contacting sensing of the rotational state of a rotor (10). The rotor has a surface divided into an electrically conductive part (1e) and a nonconductive part (1f). Three electric coils (2a, 2b, 2c) are each included in a respective parallel resonant circuit and are applied close to and with their longitudinal axes oriented towards the rotational path of the electrically conductive part of the rotor. The resonant oscillations are damped depending on the rotational position of the rotor. The rotational state is evaluated with an electronic circuit. In a liquid-flow meter, the coils may be applied in the dry part of the meter.
    Type: Grant
    Filed: July 2, 2001
    Date of Patent: February 1, 2005
    Assignee: Elster Messtechnik GmbH
    Inventors: Tord Kjellin, Staffan Ralberg
  • Patent number: 6628741
    Abstract: A shaft revolution counter including one or more reed magnetic sensors interacting with one or more magnets attached to the shaft. The interaction generates voltage spikes in the reed magnetic sensors that are used as input signal to an electronic non-volatile counter, as well as its sole power source.
    Type: Grant
    Filed: November 20, 2001
    Date of Patent: September 30, 2003
    Assignee: Netzer Precision Motion Sensors Ltd.
    Inventor: Yishay Netzer
  • Patent number: 6612188
    Abstract: The present invention provides for a self-powered fluid meter that uses the kinetic energy of a fluid being measured to provide power for circuitry that may perform functions related to the fluid measurement. An element is placed within a rotating magnetic field created from the kinetic energy of a fluid. This element creates an electrical pulse to power the circuitry.
    Type: Grant
    Filed: January 3, 2001
    Date of Patent: September 2, 2003
    Assignee: Neptune Technology Group Inc.
    Inventor: David Hamilton
  • Patent number: 6502468
    Abstract: A metering pulse transducer for utility meters, including meters for water, gas and electric service, includes a rotor (20) with five magnetically switchable elements (22-26) spaced around the axis of rotation (21), a sensing coil (27) disposed around the rotor (20), and two permanent magnets (29, 30) disposed diametrically across the rotor (20) and positioned with equal and opposite polarity such that their magnetic fields (51, 52) extend laterally to reach the path of travel (53) of the magnetically switchable elements (22-26), such that when the rotor is rotated, electric pulses are generated as a result of the magnetically switchable elements (22-26) passing the permanent magnets (29, 30). A rotor (20) having five switchable magnetic elements (22-26) disposed seventy-two degrees (72°) apart generates ten pulses per revolution of the rotor (20).
    Type: Grant
    Filed: December 27, 1999
    Date of Patent: January 7, 2003
    Assignee: Badger Meter, Inc.
    Inventor: Ray J. Thornborough
  • Patent number: 6481293
    Abstract: A flowmeter includes a conduit having an elbow portion and a straight section downstream of the elbow. A turbine is mounted inside the conduit in the straight section adjacent the elbow portion. The turbine occupies less than the entire cross section of the conduit and is disposed adjacent the side of the conduit which receives the laminar flow exiting from the elbow portion. A permanent magnet is mounted on the turbine, the rotation of which is picked up by a Hall-effect sensor mounted in a cavity in a wall of the conduit.
    Type: Grant
    Filed: December 27, 1999
    Date of Patent: November 19, 2002
    Assignee: Osmonics, Inc.
    Inventors: Thomas J. Walczak, Kenneth J. Sieth, Thomas P. Honzelka
  • Patent number: 6439062
    Abstract: An apparatus for detecting an anomaly in a flowing stream includes a set of blades rotatably suspended in the flowing stream and aligned with a normal flow direction of the flowing stream. The blades are configured to rotate at one rate when the anomaly is present in the flowing stream and to rotate at a different rate when the anomaly is absent from the flowing stream. A device is prescribed for measuring rate of rotation and rotation direction of the blades.
    Type: Grant
    Filed: July 30, 2001
    Date of Patent: August 27, 2002
    Inventors: Stephen T. Stark, Stephen H. Caldwell
  • Patent number: 6435042
    Abstract: A process and device for installing an encoder receiver transmitter (ERT) (30) onto a gas meter (20) prevents incorrect installation that otherwise requires meter (20) replacement. The device is a guide bracket (10) having a slot (14) for guiding an input gear (32) of an ERT (30) into engagement with a drive mechanism gear (22) of a gas meter (20). During installation, the customary index and lens are removed so that the drive mechanism gear (22) is exposed; next, the guide bracket (10) is mounted to the meter (20) by placing fasteners (16) through the mounting holes (12) in guide bracket (10) and into the index holes (24) in meter. Once the guide bracket (10) is secured, the input gear (32) is slipped through the slot (14) and a screw (36) is loosely threaded into the upper-right installation hole (34) in the ERT (30) and through the upper-right casing hole (26) in the meter (20) so that the ERT (30) pivots about this point.
    Type: Grant
    Filed: July 16, 2000
    Date of Patent: August 20, 2002
    Assignees: Tru-Check INC, Public Service Company of Colorado INC
    Inventors: Paul D Puseman, Steven D Brunmeier
  • Publication number: 20020083778
    Abstract: The present invention provides for a self-powered fluid meter. The kinetic energy of a fluid being measured is used to provide power for circuitry that may perform functions related to the fluid measurement.
    Type: Application
    Filed: January 3, 2001
    Publication date: July 4, 2002
    Inventor: David Hamilton
  • Patent number: 6397686
    Abstract: A pick-up assembly for use in a liquid dispensing system utilizes a Hall-effect sensor integrated within a flowmeter to provide a measure of the rotational velocity of the rotor and hence the flow rate of liquid being transmitted through the liquid line. The rotor is modified to include at least one recessed area defined in its outer surface and which exhibits magnetic properties. The Hall-effect sensor includes a first and second Hall-effect element each generating a respective channel signal that is representative of the rotational velocity of the rotor. The Hall-effect sensor is suitably arranged with respect to the rotor so as to enable each one of the recessed areas to exert a characteristic magnetic influence upon the Hall-effect sensor during shaft rotation. The variable magnetic flux experienced by the Hall-effect sensor appears as a corresponding variation in the voltage signal generated by the sensor.
    Type: Grant
    Filed: August 9, 1999
    Date of Patent: June 4, 2002
    Assignee: Tokheim Corporation
    Inventors: Tom Taivalkoski, Harald Görres, Hans Ulrich Bloss
  • Patent number: 6389909
    Abstract: A system for monitoring the flow of water through a pipe. A metering device is located in a pipeline. A transmitting unit including a sensor is contained within a housing which has a frame projecting horizontally outwardly from the housing. A clip having an elongated band and a “U” shaped clasp at either end has an inner clasp portion and an outer catch portion to hold the meter against the housing.
    Type: Grant
    Filed: March 13, 2000
    Date of Patent: May 21, 2002
    Inventors: Dwight N. Johnson, Daivd A. Saar, Wade W. Smith, Christian Siebert
  • Patent number: 6284129
    Abstract: A totalization meter system for a water treatment device, the device having an inlet aperture and an outlet aperture, and a channel for channeling water between the inlet and outlet apertures. A flow reactive device is positioned in the channel and is exposed to the flowing water, and a signal generating member is positioned on the flow reactive device. A switch is positioned proximately to the flow reactive device, and is sensitive to the proximity of the signal Generating member. The switch is able to communicate electric signals indicative of the motion of the signal generating member. A resettable processor having a Performance threshold programmed therein and an output device is included. The microcontroller is in electrical communication with the switch for receiving electrical signals from the switch. The switch is cap able of sensing the characteristics of the flow reactive device and communicates electrical signals representative of the characteristics to the microcontroller.
    Type: Grant
    Filed: August 1, 2000
    Date of Patent: September 4, 2001
    Assignee: Water Pik, Inc.
    Inventors: Edward C. Giordano, Thomas W. Graves, James M. Jennings, Mark Vander Berg, William James A. Storer, Douglas R. Gibbs, Douglas A. Lonsinger
  • Patent number: 6267013
    Abstract: An apparatus for detecting an anomaly in a flowing stream includes a set of blades rotatably suspended in the flowing stream and aligned with a normal flow direction of the flowing stream. The blades are configured to rotate at one rate when the anomaly is present in the flowing stream and to rotate at a different rate when the anomaly is absent from the flowing stream. A device is prescribed for measuring rate of rotation and rotation direction of the blades.
    Type: Grant
    Filed: November 18, 1998
    Date of Patent: July 31, 2001
    Inventors: Stephen T. Stark, Stephen H. Caldwell
  • Patent number: 6256590
    Abstract: In an electromagnetic flowmeter, the conventional derivation of flow velocity is corrected or replaced by an alternative calculation to take into account estimated non-linear dependence of field strength produced by the coil with applied coil current. This can be used to enable more accurate measurement, over a wider range of coil current. The improved accuracy allows the coil current to be adjusted to optimise power consumption; the adjustment of coil current in this manner is another aspect of the invention.
    Type: Grant
    Filed: December 18, 1998
    Date of Patent: July 3, 2001
    Assignee: ABB Instrumentation Limited
    Inventor: Ray Keech