The Foxboro Company

David A Richardson

Robert J Robinson

Allan L Flanagan

George E Sgourakes

Everett O Olsen

Donald C Simpson

John R Curran

Richard O Driscoll

Bucket liner

Dispensable tube cap and retention assembly

Multi function stud climbing and carpentry tool

Reading values, setting values and setting configuration options within a complex programmable apparatus is simplified, by chaining all user interaction points into a single path, cross linking portions of the main path into subpaths and providing keys that step the user according to his selection along the main path, along the subpaths, and between the subpaths. A two part display indicating the general and specific positions clarify the locations and the options available.

Method and apparatus for configuring a controller

Reading values, setting values and setting configuration options within a complex programmable controller is simplified, by chaining all user interaction points into a single path, cross linking portions of the main path into subpaths and providing keys that step the user according to his selection along the main path, along the subpaths, and between the subpaths. A two part display indicating the general and specific positions clarify the locations and the options available.

Apparatus for converting an analog-format electrical signal or quantity (such as the magnitude of an electrical circuit element) into a corresponding pulse-format signal, preferably in the form of a train of periodic pulses the lengths of which are controllable as a percentage of the cyclic period. A pulsed duty-cycle signal is developed in a negative feedback loop around an integrator having an analog-format input signal. The integrator output controls the d-c level of an up-and-down ramp signal which is fed to a comparator to produce pulses during the times the ramp voltage is above (or below) the firing threshold of the comparator. These pulses control a switch between the integrator input and a reference voltage so as to produce a negative feedback signal for the integrator. The negative feedback action controls the d-c level at the integrator ouptut and thereby sets the pulse duty-cycle to a value such that the average signal level through the pulsed switch to the integrator input relates in prescribed fashion to the applied input signal. The duty-cycle signal developed through such feedback action corresponds directly to the magnitude of the applied input signal.

Apparatus for converting analog-format signals to pulse-format signals

Instrument system including an electronic transmitter for a vibrating-wire differential-pressure sensor at a field location and connected by a two-wire line to a control room. The transmitter includes an oscillator to produce vibrations of the wire at its resonant frequency, and applies to the two-wire line a corresponding alternating voltage signal. The control room equipment converts this raw measurement data to an analog measurement signal. The control room equipment provides for adjustment of the zero and span of this signal, and for linearization with respect to the input differential pressure. The two-wire line carries a direct-current component the average value of which is automatically adjusted at the control room to match the scaled and linearized analog measurement signal. This line current passes through a meter at the transmitter to provide field service personnel with a visual indication of the value of the scaled and linearized measurement signal.

Instrumentation system with electric signal transmitter

A force-measuring instrument of the vibrating-wire type wherein the mechanical components are located at the force-measuring location and the vibrating wire is coupled through a two-wire transmission line to electronic circuitry at a distant location. The electronic circuitry includes means to excite the vibrating wire and to produce a d-c measurement output signal corresponding to the frequency of vibrations. The electronic circuitry further includes function-generating means to establish a closely-linear relationship between the output current and the force applied to the wire. Means also are incorporated in the electronic circuitry for adjusting the zero and span of the instrument, and this can be done without interaction between the adjustments.

Electric signal transmitter for vibrating-wire sensor

A vortex-shedding flow-sensing instrument comprising a flat-faced vortex-generating plate integral with a downstream sensor-bar having flat sides set back laterally with respect to the rows of vortices shed from the edges of the vortex-generating plate. The side surfaces of the plate are tapered inwardly at a moderate angle, and extend downstream a short distance to rear surfaces at right angles with respect to the direction of fluid flow. The downstream end of the sensor bar comprises a tail piece the side surfaces of which are tapered inwardly at a moderate angle, and extend downstream a short distance to a rear surface perpendicular to the direction of fluid flow. The sensor bar carries a liquid-filled capsule having as side walls a pair of flexible diaphragms effectively in the plane of the sensor-bar side surfaces. These diaphragms are of moderately large area so as to respond to a relatively large portion of the vortex energy. The diaphragms transmit alternating vortex pressure pulses interiorly of the capsule to a sensing element in the form of a ceramic disc having piezo-electric properties. The resulting alternating voltage signal developed by this element is coupled through lead wires to an amplifier arranged to produce a flow signal suitable for transmission over relatively long distances.

Vortex flow meter transducer

A positioning device for controlling a member such as a pen of a chart recorder, wherein the positioning motion is produced by a wire formed of temperature-responsive material (Nitinol) exhibiting a martensitic transformation which contracts the wire when its temperature is increased within a predetermined temperature range, and relaxes the wire when cooled within that range. The wire is maintained under tension by a spring having a negative spring-rate. This spring cooperates with internally generated forces and the elasticity of the wire material to produce contraction/expansion length changes of the wire in response to changes in its temperature. Electrical circuitry for controlling the wire temperature is disclosed, and includes means for inductively developing a frequency-modulated pulse-current through the wire.

Positioning device using negative spring-rate tensioning means

A deviation meter, responding to a deviation signal, is mounted on a turntable which rotates in response to a set point adjustment. Rotation of the turntable maintains the null position of the deviation meter pointer at a scale position corresponding to a set point value, so that a direct readout of the actual measurement value is provided.

Method and apparatus for displaying industrial process control parameters

Flow-metering apparatus of the vortex-shedding type wherein an obstruction in a flowing fluid develops a series of vortices which are sensed by a pressure-responsive piezo-electric element to produce an alternating voltage having a frequency corresponding to the fluid flow rate. The piezo-electric voltage signal is processed by electronic circuitry to provide for precise detection of the zero-crossings of the voltage alternations. The resulting frequency signal controls the charge/discharge characteristics of a set of capacitors, with the average charging current corresponding in magnitude to the frequency of vortex shedding. This average current controls an output amplifier in a feedback arrangement to produce a relatively high-powered d-c flow signal over a two-wire transmission line leading to a remote station. In another arrangement, a high-powered pulsating flow signal is developed for transmission over a three-wire transmission line leading to a remote station.

Vortex flow meter transmitter including piezo-electric sensor

A positioning device for controlling a member such as a pen of a chart recorder, wherein the positioning motion is produced by a wire formed of temperature-responsive material (Nitinol) exhibiting a martensitic transformation which contracts the wire when its temperature is increased within a predetermined temperature range, and relaxes the wire when cooled within that range. The wire is maintained under tension by a spring having a negative spring-rate. This spring cooperates with internally-generated forces and the elasticity of the wire material to produce contraction/expansion length changes of the wire in response to changes in its temperature. Electrical circuitry for controlling the wire temperature is disclosed, and includes means for inductively developing a frequency-modulated pulse-current through the wire.

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Sheldonville, MA, United States of America

David A Richardson