Abstract:
An oil filled pressure transducer which exhibits reduced backpressure and utilizes a smaller volume of oil employs a glass pre-form which has a plurality of pin accommodating apertures and has an oil tube accommodating aperture. There are a plurality of contact pins inserted into the pin accommodating apertures and which extend from the top to the bottom surfaces of the pre-form. There is an oil fill tube inserted into the oil tube accommodating aperture, which oil fill tube extends from the bottom to the top surface of the pre-form with one end of the tube extending above the top surface of the pre-form. There is a glass alignment plate which has an alignment aperture for encircling the extended oil fill tube and has a sensor accommodating shaped aperture located at a predetermined position from said alignment aperture. When the glass alignment plate is being accommodated on the top surface of the pre-form by inserting the alignment aperture about the oil tube, the position of a sensor module is accurately determined based on the position of the sensor accommodating aperture. A sensor module is now placed in the shaped aperture of the alignment plate and makes contact with the pins to enable the sensor contacts to contact the pins. A header surrounds the sensor as positioned on the glass pre-form and a diaphragm is then placed to cover the top surface of the header to create a space between the top surface and the sensor. This space contains oil which is placed in the space by the oil fill tube. Due to the presence of the glass alignment plate, which has a given thickness, the volume of oil now required is much less than the volume required in the prior art, thus substantially reducing backpressure and further assuring that the sensor device is always properly aligned with respect to the pins.
Abstract:
A combined wet-wet differential transducer and a gage pressure transducer located in the same housing, comprising a semiconductor chip which comprises a gage sensor chip on one section and a differential sensor chip on a second section. Lach sensor chip has a Wheatstone bridge comprising piezoresistors and is responsive to an applied pressure. The gage chip and the differential chip are placed in a header having a front section and a back section adapted to receive a first and second pressure, respectively. A central section adjoins the front and back sections to form an H shaped header. The sensors are in communication with first and second pressure ports such that the absolute sensor provides an output indicative of a pressure applied to a first port and the differential sensor provides an output indicative of the pressure difference between the first and second pressure ports.
Abstract:
There is disclosed a transducer employing radiation hardened electronics. Essentially a sensor assembly is positioned in a front section of a housing where the sensor assembly is coupled to an electronic module via terminals which connect the sensor to the module. The electronic module assembly is surrounded by an internal tungsten housing which is formed from a first tungsten “U” shaped cross-sectional member coupled to a second tungsten “U” shaped cross-sectional enclosure. The two members are coupled together and totally surround the electronic assembly. The members as held together are positioned within the housing by outer shell members to form a complete housing assembly whereby the electronic assembly and its associated terminal pins are totally surrounded by the tungsten holder section and the tungsten enclosure section.
Abstract:
There is disclosed a multiple axis load cell or controller in which axial and torsion measurements are decoupled while maximizing the outputs of both measurements. The active member of the load cell is a wheel with dual beams as the spokes. The wheel thus has four spokes or four beam members, each spoke is a pair of rectangular cross-section beams, orthogonal to each other. The beams have strain gages on the wide surfaces which measure the bending strain which is proportional to torsion or the axial input. There is an inner beam section and an outer beam section associated with each spoke and orthogonal to each other. The outer beams have the wide surface normal to the axis of the load cell. This beam section is more sensitive to the axial tension/compression input. The inner beam sections have their wide surface parallel to the axis of the load cell and are much less sensitive to bending but are sensitive to torsion. Therefore when a torsion or twisting motion is applied to the load cell, the inner beams with their wide surface parallel to the axis of the wheel are more sensitive and bend more. These beams experience bending as a result of the torsion input and have strain gages formed in a Wheatstone bridge arrangement to provide an output proportional to the torsion. The outer beams also have gages mounted thereon which are also wired in a Wheatstone bridge configuration and which Wheatstone bridge output of these gages are proportional to the axial force.
Abstract:
A pressure transducer has an H-shaped header having a front and a back section. The front and back sections are of equal diameter and are circular. Each front and back section has a depression with a diaphragm covering the depression. Each diaphragm is of equal size and the depressions communicate one with the other via a central channel in the central arm of the H. A pressure sensor communicates with the channel, where the pressure sensor responds to a first pressure applied to the first diaphragm and a second pressure applied to the second diaphragm. The pressure sensor produces an output equal to the difference in pressure. The differential pressure inducer having both diaphragms of the same size and still enabling leads from the sensor to be brought out.
Abstract:
A semiconductor filter is provided to operate in conjunction with a differential pressure transducer. The filter receives a high and very low frequency static pressure attendant with a high frequency low dynamic pressure at one end, the filter operates to filter said high frequency dynamic pressure to provide only the static pressure at the other filter end. A differential transducer receives both dynamic and static pressure at one input port and receives said filtered static pressure at the other port where said transducer provides an output solely indicative of dynamic pressure. The filter in one embodiment has a series of etched channels directed from an input end to an output end. The channels are etched pores of extremely small diameter and operate to attenuate or filter the dynamic pressure. In another embodiment, a spiral tubular groove is found between a silicon wafer and a glass cover wafer, an input port of the groove receives both the static and dynamic pressure with an output port of the groove providing only static pressure. The groove filters attenuate dynamic pressure to enable the differential transducer to provide an output only indicative of dynamic pressure by cancellation of the static pressure.
Abstract:
A leak detector apparatus for a pressurized cylinder having a cylinder of a radius (r) with a slidable piston in the cylinder with a gas filled chamber positioned between a cylinder end and the piston face. The length (L) of the chamber is calculated according to load changes on the piston where the volume (Vc) of the chamber changes. The pressure and temperature of the chamber are measured as well as the length. These values are inputted to a processor to solve the ideal gas law equation PV=nRT where a change in n for a change in length indicates a leak.
Abstract:
A pressure sensing apparatus including: at least one deflectable diaphragm having a center, wherein each diaphragm supports: at least one positive piezoresistive gauge and at least one negative piezoresistive gauge coupled in series across a voltage differential in a half-Wheatstone bridge configuration having an output between the positive and negative piezoresistive gauges; and, a compensating piezoresistive gauge coupled in series with the half-Wheatstone bridge configuration across the voltage differential; wherein, the compensating piezoresistive gauge is nearer the center of the diaphragm than the negative piezoresitive gauge, the negative piezoresitive gauge is nearer the center of the diaphragm than the positive piezoresitive gauge, and the compensating piezoresistive gauge linearizes the half-Wheatstone bridge output.
Abstract:
A piezoresistive sensor device and a method for making a piezoresistive device are disclosed. The sensor device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The sensor device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The sensor device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making a piezoresistive sensor device, comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the piezoresistive sensor and associated transducer in ultra high temperature applications.
Abstract:
A single pressure sensing capsule has a reference pressure ported to the rear side of a silicon sensing die. The front side of the silicon sensing die receives a main pressure at another port. The silicon sensing die contains a full Wheatstone bridge on one of the surfaces and within the active area designated as the diaphragm area. Thus, the difference of the main and reference pressure results in the sensor providing an output equivalent to the differential pressure, namely the main pressure minus the reference pressure which is the stress induced in a sensing diaphragm. In any event, the reference pressure or main pressure may be derived from a pump pressure which is being monitored. The pump pressure output is subjected to a pump ripple or a sinusoidally varying pressure. In order to compensate for pump ripple, one employs a coiled tube. The tube length is selected to suppress the pump ripple as applied to the sensor die. In this manner, the pump ripple cannot cause resonance which would result in pressure amplification and which pressure amplification would destroy the sensor.