Tward 2001 Limited

Other

Trw Limited

Emanuel Tward

Philip D Junkins

Alan M Lovelace

Chung K Chan

A multistage pulse tube cooler in which a portion of the heat from each successively lower-temperature pulse tube cooler is rejected to a heat sink other than the preceding higher-temperature pulse tube cooler, thus substantially improving the overall efficiency of the multistage cooler. Multistage pulse tube coolers of the prior art reject all the heat from each successively lower-temperature pulse tube cooler to the preceding higher-temperature pulse tube cooler, thus imposing a large cooling load on the higher-temperature pulse tube coolers which considerably reduces the overall efficiency of the cooler.

Multistage pulse tube cooler

A method and instrument for comparing the dielectric properties of a flowing stream of fluid with the dielectric properties of a reference fluid in which a uniquely configured multi-capacitor sensor, formed of a first pair of capacitors having like dielectric spaces within which the reference fluid is maintained under non-flow conditions as the dielectric material and a second pair of capacitors having like dielectric spaces within which a sample portion of the flowing stream of fluid is continuously passed as the dielectric material, comprises all of the capacitance elements of a Wheatstone bridge circuit in a single cellular unit in which the capacitive elements are all subjected to the same sample fluid, temperature and pressure environment and which is not sensitive to stray capacitances. Each pair of capacitors forms opposing sides of the Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across a first set of bridge terminals at opposite corners of the bridge and a current detection circuit is connected across a second set of bridge terminals independent of the first set of terminals and at opposite corners of the bridge. Detection and measurement of the current value of the bridge is translated into a value of dielectric constant for the fluid sample in direct linear relationship with the current value.

Capacitive system for monitoring the dielectric properties of flowing

A capacitive type pressure, force or displacement sensing transducer comprised of a mating pair of spaced dielectric elements each carrying a pair of capacitive elements forming two like capacitors of variable capacitance value depending upon the variable spacing distance between the dielectric elements and two like capacitors of fixed capacitance value. The pair of variable value capacitors and pair of fixed value capacitors comprise all of the capacitance elements of a Wheatstone bridge circuit in a single structural unit in which such capacitive elements are all subjected to the same temperature and pressure environment and which is not sensitive to stray capacitances. Each pair of capacitors forms opposing sides of the Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across a first set of bridge terminals at opposite corners of the bridge and a current detection circuit is connected across a second set of bridge terminals independent of the first set of terminals and at opposite corners of the bridge. Detection and measurement of the current value of the bridge circuit is translated into a value of force, pressure or motion applied to the transducer unit in direct linear relationship with the current value as determined by the separation distance between the spaced dielectric elements of the transducer.

Multiple capacitor transducer

A system for measuring the level or volume of a fluid within a fluid storage vessel which comprises: a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and a pair of capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel. The four capacitors of the sensor are connected together to form the four capacitive sides of a Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor. A detection circuit is connected across the bridge to a second set of bridge terminals (independent of said first set of terminals) and at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor. The current value in the detection circuit is measured and indicates the value as a fluid level or fluid volume measurement in direct linear relationship with the current value. The system may be used for volume measurement with respect to a wide variety of multi-component fluid systems as long as the dielectric constants for the two or more components are different.

Fluid level measuring system

A method for measuring the level or volume of a fluid within a fluid storage vessel which comprises: providing a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and two capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel and with the fluid in the spaces consisting of a pair of capacitors of variable capacitive value; connecting the four capacitors of the sensor together to form the four capacitive sides of a Wheatstone bridge circuit; applying a source of alternating current of constant voltage and set frequency across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor; interrogating the bridge circuit through a detection circuit connected across the bridge to a second set of bridge terminals independent of said first set of terminals and at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor; and measuring the current value in the detection circuit and indicating the value as a fluid level or fluid volume in direct linear relationship with the current value. The method may be used for volume measurement with respect to a wide variety of multi-component systems as long as the dielectric constants for the two or more components are different.

Method of measuring and indicating fluid levels

A capacitive type pressure sensing transducer comprised of two dielectric elements bearing four like plates or discs of conducting material and two like conductive pressure sensitive diaphragms which together form two like plate type capacitors of fixed capacitance value and two like plate type capacitors of variable capacitance value. The pressure sensitive diaphragms span like recessed areas in one face of one of the dielectric elements to form two like pressure chambers. The four conducting discs are positioned as matching pairs of capacitive plates on each side of the other dielectric element and together form the two fixed value capacitors. The pressure sensitive diaphragms and one of the conducting disc pairs are aligned to form the two variable value capacitors with their capacitance value depending upon the variable spacing distance of the diaphragms from the aligned discs in response to pressure applied to the diaphragms. The pair of variable value capacitors and pair of fixed value capacitors comprise all of the capacitance elements of a Wheatstone bridge circuit in a single transducer unit in which such capacitive elements are all subjected to the same temperature and pressure environment and are not sensitive to stray capacitances. A source of alternating current is applied across a first set of bridge terminals and a current detection circuit is connected across a second set of bridge terminals and translates current value into a value of pressure applied to the transducer.

Pressure transducer

A capacitive type pressure sensing transducer comprised of a housing having a pressure sensitive element which interfaces with an applied pressure force to be sensed and measured and which moves in response to force changes to vary the volume of the housing in direct relation to such changes. The housing is filled with a fluid which is in fluid flow communication with a multi-capacitor fluid level sensor. The sensor is formed of a first pair of plate type capacitors of like fixed capacitive value and a second pair of plate type capacitors having like open dielectric spaces for receiving varying levels of fluid from the transducer housing in response to changes in the volume of the housing. Thus, a change in pressure applied to the pressure sensitive element of the transducer produces a corresponding change in the fluid level within the dielectric spaces of the second pair of capacitors of the sensor and a corresponding change in the capacitance value of such capacitors. The capacitors of the sensor are electrically connected into a classic alternating current Wheatstone bridge circuit and the current flow value of the circuit is measured as a direct, linearly-related value of the pressure force applied to the transducer.

Capacitive pressure transducer

A manometric method and instrument for the continuous detection and measurement of differential pressures which includes a uniquely configured multi-capacitor sensor system. The sensor system is formed of a first pair of plate type capacitors having like dielectric spaces within which a first strata of fluids is maintained and subjected to one pressure force and a second pair of plate type capacitors having like dielectric spaces within which a second strata of fluids is maintained and subjected to another pressure force. The dielectric spaces of each pair of capacitors are interconnected at their lower ends so that the pairs of dielectric spaces form the legs of a classic U-tube manometer whereby the first strata of fluids and the second strata of fluids assume equilibrium positions within their respective dielectric spaces in relation to the densities of such fluids and the respective applied pressure forces. The pairs of capacitors comprise all of the capacitance elements of an alternating current Wheatstone bridge circuit. Detection and measurement of the current value of the bridge is translated in linear relationship into a differential pressure value between the pressure forces applied to the manometric instrument.

Capacitive system for manometric detection and measurement of

A fluid level or fluid volume sensor or probe for mounting in a fluid storage vessel for sensing the level or volume of the fluid within the vessel which is comprised of four like electrically conductive capacitor elements each formed to present two electrically connected capacitive plates disposed in angular relation to each other. Electrical insulating material constitutes centrally located means for mounting the capacitor elements in fixed spaced relationship from one another around such mounting means and for positioning the elements so that each capacitive plate thereof defines with a capacitive plate of the next adjacent capacitor element a dielectric space therebetween whereby the mounted capacitor elements together form four like dielectric spaces. Material of known constant dielectric value fills two of the dielectric spaces thereby forming with their respective space defining capacitive plates two capacitors of known fixed and substantially like capacitive value. The remaining two dielectric spaces are open to receive varying levels of fluid thereby forming with their respective capacitive plates, and the fluid within the spaces, two capacitors of variable capacitive value. The sensor or probe is not limited in its application to fluid level or fluid volume measurements of liquids in vessels and may be used for volume measurement with respect to a wide variety of multi-component systems (including liquid/liquid, liquid/gas, liquid/solid, solid/gas, etc.) as long as the dielectric constants for the two or more components are different.

Fluid level sensor

A tubular shaped fluid level or fluid volume sensor for mounting in a fluid storage vessel for sensing the level or volume of the fluid within the vessel which comprises: a first pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the capacitor elements being spaced from one another and shaped and arranged to generally define together the outer periphery of the tubular sensor; and a second pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the second pair of capacitor elements being positioned within and spaced from the first pair of capacitor elements and being spaced from one another and shaped and arranged to generally define together the inner periphery of the tubular sensor. Electrical insulating material located between the capacitor elements defining the other periphery of the sensor and the capaictor elements defining the inner periphery of the sensor for mounting the pairs of capacitor elements in fixed spaced relationship from one another and for positioning the elements so that each capacitive plate area thereof defines with a capacitive plate area of the next adjacent capacitor element a dielectric space therebetween so that the mounted capacitor elements together form four like dielectric spaces. Material of known constant dielectric value fills two of the dielectric spaces thereby forming with their respective space defining capacitive plate areas two capacitors of known fixed and substantially like capacitive value. The remaining two dielectric spaces are open to receive varying levels of fluid thereby forming with their respective capacitive plate areas, and the fluid within the spaces, two capacitors of variable capacitive value.

Multi-capacitor fluid level sensor

A symmetrical adsorption pump/compressor system having a pair of mirror image legs and a Joule Thomson expander 40, or valve, interposed between the legs thereof for providing a new, efficient refrigeration cycle. The system further includes a plurality of gas operational heat switches 48a, 48b, 48c, and 48d adapted selectively to transfer thereto heat from a thermal load 44 and to transfer or discharge heat therefrom through a heat projector 46, such as a radiator or the like. The heat switches comprise gas pressurizable chambers adapted for alternate pressurization in response to adsorption and desorption of a pressurizing gas confined therein.

Growing community of inventors

Northridge, CA, United States of America

Emanuel Tward