Data Instruments, Inc.

General Automotive Specialty Co., Inc.

Herman W Erichsen

Louis J Panagotopulos

Mark Levine

William T Holmes

Edward W Baumgartner

Michael A Amoroso, Jr

A differential pressure transducer for measuring a pressure differential between a first pressure source and a second pressure source. The differential pressure transducer includes a displacement element and a sensing element coupled to the displacement element. The displacement element moves in a linear direction and deflects the sensing element to provide a signal that is proportional to the movement of the displacement element when the first and second ends are subjected to the pressures at the pressure sources. The differential pressure transducer can also include a force transfer beam that connects the displacement element and the sensing element. The sensing element can include a sensing beam and a strain gauge mounted on the beam to provide an electrical signal proportional to the strain in the beam induced by the deflection of the beam. The force transfer beam and the sensing element can be portions of a unitary member formed as a stamped part. The displacement element can be a single piston or it can include a pair of force collectors attached to opposing sides of the force transfer beam. Additionally, the transducer can include overload protection to limit the movement of the displacement element and the force transfer beam. Further, the strain gauge is disposed on a portion of the beam that is externally accessible so as to improve the assembly and maintenance of the transducer.

Differential pressure transducer

A sensing circuit includes a passive electrical network which has a first electrical property responsive to fluid pressure, and a second electrical property responsive to fluid temperature. A network output is responsive to the first property to a first extent, and to the second property to a second extent. The first and second extents are related in the same manner as a physical property of the fluid (other than its pressure or temperature) relates to its pressure and temperature. The network can include a strain gage that has a gage factor relating the pressure in the fluid to the first electrical property, and a temperature coefficient of gage factor responsive to the fluid temperature. The network can operate according to a gas law and indicate the amount of gas in a tank.

Measuring the quantity of a gas in a tank

A beam-type strain gage pressure transducer is disclosed having strips of piezo-resistive material supported on a sensing beam, one being subject to compression and another to tension in response to applied pressure. The beam structure may be made by screw machine techniques to form a beam integral with a circular base structure. A highly flexible diaphragm permits force generated by application of pressure to be transmitted entirely to the beam. Components and construction are suited to high production and automated assembly techniques.

Pressure transducer

The invention improves upon the diaphragm/beam-type transducers and method of manufacturing same described in U.S. Pat. No. 4,368,575. The new transducers and method of manufacture utilize strips or slivers of silicon or germanium which are larger than the individual strips used in the apparatus and method described in U.S. Pat. No. 4,368,575 by an amount sufficient to permit (a) the formation of two gages on each strip and (b) the forming of bonding pads on each gage. The bonding pads are formed on the gage strip before the strip is bonded to the beam, so that formation of the bonding pads and bonding of the strip to the beam can be handled automatically. The strips are mounted to one side of the midpoint of the beams, so that when a diaphragm/beam is deflected by application of a fluid pressure, one of the two gages will undergo a tension strain while the other gage will undergo a compression strain. Because both gages form part of the same silicon or germanium strip, they tend to be virtually identical in physical and electrical properties, thereby simplifying calibration of the resulting transducers.

Pressure transducers

Method of manufacturing pressure transducers

An improved pressure transducer is formed from selectively formed elements including those made from sheet materials of predetermined thicknesses and those made from brazing materials so as to form brazing preforms. The elements are easily assembled and heated so as to braze the elements together to form the transducer.

Pressure transducer--method of making same

An improved pressure transducer and method of making the transducer is disclosed. Generally, the transducer is made from sheet materials and is designed to incorporate the advantages of both the beam-type and diffused diaphragm type transducer while reducing or eliminating many of the disadvantages. The product is designed so that multiple units can be provided from a single multi-sheet composite with a relatively high reproducibility at relatively low cost.

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Holliston, MA, United States of America

Herman W Erichsen