Abstract: A pressure switch wherein the interior of a casing is divided by a partition into a fluid chamber fed with a fluid the pressure of which is to be detected, and a working chamber in which a switch mechanism is housed. A rod extends slidably through the partition, provided at its one end with a pressure-receiving portion which is adapted to receive a fluid pressure in the fluid chamber, and projecting at the other end portion thereof into the working chamber so as to change the switching mode of the switch mechanism in accordance with displacement, which occurs due to a fluid pressure applied to the pressure-receiving portion, of the rod to the end thereof which is on the side of the switch mechanism. Springs urge the rod towards the fluid chamber. The fluid chamber is further provided therein with a first spring member the force of which constitutes a part of the desired force of the rod-urging spring.

Abstract: A pressure-operated electric switch assembly of the diaphragm type wherein a housing mounted diaphragm actuates a snap action switch adjustable in the housing to vary the switch operating pressure. The pressure setting may be varied externally by the user upon manual rotation of a switch sealing boot and the setting may be visually observed from indicia surrounding the housing that cooperate with a pointer on the boot.

Abstract: A pressure change sensor includes a flexible hollow body to receive pressure changes, an inner body in said flexible hollow body, the inner body being of a size less than and a shape different from the hollow of said hollow body to prevent total occlusion of the hollow body interior under pressure, and a fluid operated switch in fluid communication with the interior of the hollow body responsive to pressure changes applied to the hollow body.

Abstract: A pressure gauge including: a deformable element; a rigid guard element surrounding the deformable element to form an engagement face; and means for sensing the deformation of the deformable element as an indication of pressure.

Abstract: An apparatus is provided for sensing changes in pressure and for generating optical signals related to said changes in pressure. Light from a fiber optic illuminates a fluorescent composition causing it to fluoresce. The fluorescent composition is caused to more relative to the end of the fiber optic in response to changes in pressure so that the intensity of fluorescent emissions collected by the same fiber optic used for illumination varies monotonically with pressure.

Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: Fluid density measuring apparatus and method for directly measuring fluid density or indirectly measuring pressure, temperature, acceleration, flow velocity, differential pressure and other parameters affecting the apparatus. The apparatus includes a generally rigid hollow housing having openings through which fluid may flow to the interior of the housing, and a vibratory single-ended tuning fork mounted in the housing. The apparatus also includes circuitry for causing the tines of the tuning fork to resonate, for example, 180 degrees out of phase in a transverse direction, with the frequency of the tines varying with variation in the density of the fluid surrounding the tines. Circuitry is also included for determining the frequency at which the tuning fork tines resonate. When the density of the fluid into which the housing is placed changes, the frequency of vibration of the tines of the tuning fork is caused to change to provide a measure of the density change.

Abstract: A pressure dome that is attached to a transducer housing by springs is provided with means for limiting the amount by which the springs can be flexed so as to prevent them from being damaged. The springs are of the beam type and projections extending from them engage stops on the body of the dome so as to limit their movement.

Abstract: A piezoelectric fluid pressure fluctuation frequency sensor, preferably for a vortex-shedding flowmeter. A piezoelectric transducer is located in a sensor chamber between and in physical contact with a diaphragm and a chamber surface. Pressure fluctuations in a von Karman vortex street outside the diaphragm compress the transducer, between the diaphragm and the chamber surface. The transducer generates a responsive electrical signal which is representative of the pressure fluctuations.

Abstract: A high pressure transducer, particularly for ballistic pressure measurements, with a sensor part, with a sealing part formed thereon and with a hollow mounting screw surrounding the sensor part with a clearance. The sensor part can be inserted together with the sealing part into a threaded mounting aperture in the component to be examined, whereby the sealing surface of the sealing part comes into sealing contact with a seating surface of the mounting aperture. The hollow mounting screw presses on the sealing part and produces the force necessary for sealing. The sealing surface of the sealing part is located somewhat ahead of a membrane portion while the sealing part is connected relatively elastically with the sensor part by means of a narrow web.

Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: A flow rate sensor includes a diaphragm operated switch coupled to a Venturi in a flow conduit. The apparatus includes a housing having a diaphragm defining a chamber. The chamber has a first port connected to the Venturi and a second vent port. A valve connected between the first port and the diaphragm is spring loaded so that the first port is normally open. In the absence of fluid flow, the Venturi pressure is zero under the diaphragm and the diaphragm is at rest in an up position so that the valve is open. With fluid flow through the Venturi, vacuum will build under the diaphragm so that the diaphragm will travel down until the valve closes the first port. With the valve closed, pressure under the diaphragm will increase due to flow through the vent port and the diaphragm will move up. The valve will remain closed until the diaphragm up stroke is equal to the valve stem lost motion.

Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: A hydraulic accumulator unit having a volume variable against the force of a spring and a restrictor are provided for eliminating slow pressure fluctuations in a measuring instrument responsive to fluid pressure, through which restrictor the hydraulic accumulator unit is connected to the fluid subjected to the pressure fluctuations. The measuring instrument measures the pressure in the accumulator unit.

Abstract: A vacuum pressure transducer (1) for sensing vacuum pressure levels and for developing an electrical signal indicative of the vacuum pressure sensed. A housing (3A, 3B) has an inlet (5) connected to a vacuum source (M). A flexible diaphragm (7) extends across the housing for one side of the diaphragm to be exposed to vacuum pressure, the diaphragm flexing within the housing as vacuum pressure changes. An electrical contact (13) is coupled to the diaphragm and movable therewith, and an electrical switch (25) includes a plurality of electrically conductive segments (27) arranged in a predetermined pattern. The electrical contact contacts one or more of the segments as it moves with diaphragm, each combination of segments contacted by the electrical contact at any one time representing a discrete vacuum pressure.

Abstract: A pressure responsive switching device, particularly a pressostat or thermostat, comprises an actuating element (5) which is loaded in one direction by an operating element (1) at the pressure and in the other direction by a main spring (9) by way of a force transmission device (10). The latter has a physical quantity (P.sub.k) which is variable with the force transmitted by the operating element. In addition, there is a measured value generator (23) which, depending on this physical quantity, delivers an electric analogue signal (S). The force transmission device may comprise a compensating force producer (10) in the form of an expansion element (15) which is provided with a liquid-vapor filling and a heating device (21), by which the compensating force of the force of the operating element (1) is made to follow. In this way, the switching device can deliver an analogue signal (S) corresponding to the system pressure (P) by using the same operating element (1).

Abstract: A digital system for measuring an input quantity includes an input mechanism for providing a first input in response to an input quantity to be measured, a stepper motor for providing a second input, a measuring apparatus connected to the input mechanism and to the stepper motor such that the measuring apparatus provides an output when the first and second inputs reach a predetermined relationship, and a circuit connected to the stepper motor and to the measuring apparatus for stepping the stepper motor from a reference position and for counting the steps of the stepper motor until the measuring apparatus provides the output.

Abstract: An injection timing transducer is provided for use with the fuel delivery system of a compression ignition engine. The transducer is operatively associated with the fuel flow path and provides a signal indicative of fuel pressure pulsations within the fuel delivery system. The electrical signals are representative of the derivative or rate of change of fuel pressure as a function of time and are thereby particularly suited for indicating the onset of fuel injection to the engine. The transducer includes a housing member connectable in the fuel flow path intermediate a fuel pump and injector for defining a chamber through which the fuel may pass and for providing a sensor mounting surface external to the chamber but in pressure transmitting relationship with the fluid path. A piezoelectric sensing element is affixed to the sensor mount surface of the transducer housing member.

Abstract: An improved construction is provided for fluid pressure responsive electrical switching apparatus, which achieves physical miniaturization, quick response time, sensitivity to relatively low levels of change or differential in fluid pressures, adaptability for employment in corrosive environments and under a very wide range of temperature conditions, simplicity and economy of fabrication and assembly, reliability of operation and general versatility for utilization in diverse applications. The improved apparatus involves, besides suitable housing structure that may provide for installation accommodating to various pressure and other conditions dictated by the application, a thin, wafer-like laminated switch assembly peripherally sealed in the housing structure and disposed for direct fluid communication with the fluid whose pressure is to be monitored for the purpose of controlling actuation of the switch assembly.

Abstract: Proximity sensor for determining the distance between a reflective surface and the sensor utilizes two output light guides positioned with the receiving end of one guide closer to the reflective surface than that of the other. When the surface is close to the guide ends a relatively greater intensity of light will be reflected to the second guide; when the surface is further away a relatively greater intensity of light will be reflected to the first guide. At a predetermined intermediate null position the reflected light intensities will be equal. The device has uses, inter alia, in accurately positioning objects without wear-producing contact, e.g. in numerically controlled machine tool operations; thickness sensing or thickness controlling using single or dual sensors; force sensing; liquid level indication; meter relay actuation; rotational limitation, and the like.

Abstract: A meter for divers which records and displays depth and elapsed time of dive information in LCD format including a microprocessor for recording and displaying essential dive information, a sensor, responsive to ambient pressure and variations in such pressure, and a direct digital input and tracking system for transmitting sensed information directly to the microprocessor.

Abstract: A pressure sensor and sensing method, wherein the sensor comprises a pressure responsive element movable corresponding to a pressure to be measured and a means for detecting movement of the pressure responsive element. The movement detecting element comprises two parts of switch means movable to and fro with respect to each other, and a substantially constant oscillation is applied to one part so that movement of the pressure responsive element alters a threshold value which is applied to the substantially constant oscillation in order to produce a varying pulse signal.

Abstract: An optical device for measuring both slight positive and negative pressure differences by means of a light intensity change characterized by a gradient lens having a first and second end face being mounted in a housing part with a second end face spaced from a partially reflective membrane which is secured to the housing part to form a first chamber of a first volume and a second chamber of a second volume.

Abstract: An optical device for measuring slight pressure differences by means of a light intensity change characterized by a membrane extending across a recess of a housing part to form a first chamber of a first volume which is isolated from a second chamber on the opposite side of the membrane, a right angle isosceles glass prism mounted in the recess with a hypotenuse surface facing said membrane and extending parallel thereto, an input optical waveguide coupled to one short side surface of the prism extending to the light source of a given light intensity for coupling light from said source into the prism and an output optical waveguide being coupled to the other short side surface of the prism for output coupling light from the prism to a measuring device.

Abstract: A pressure monitoring system for use with an electrofluidic device for sensing pressure includes a pump for supplying fluid to the electrofluidic sensing device. An electrical switching circuit controls the supply of fluid to the sensing device and is responsive to the external pressure level applied to the sensing device; this circuit also cyclically causes the supplied pressure to vent when the pressure of supplied fluid inside the sensing device is substantially equal to the applied external pressure, and then start the fluid supply to the device over again. This system further includes a measuring element for detecting the pressure level of the supplied fluid, and a digital meter for displaying the analogous detected pressure level during supply of the fluid.

Abstract: A pressure-measuring device which operates in digital representation comprises:a first chamber subjected to the pressure to be measured;a second chamber subjected to a reference pressure and connected to the first chamber through at least one opening fitted with a valve;a device for measuring the difference both in magnitude and in sign between the pressures prevailing respectively within the first and second chambers, said device being intended to deliver an electrical signal which is a function of said difference;a circuit for detecting the instants at which said difference attains a predetermined increment +.DELTA.P or a predetermined decrement -.DELTA.P and for detecting instants at which said difference becomes zero;an element connected to said circuit for initiating the opening of the valve or valves when the difference attains the values .+-..DELTA.

Abstract: A digital readout gauge is disclosed which, for example, may be a tire pressure gauge which is mounted in a small portable housing. A pressure chamber is formed within the housing with a valve core deflator mounted within the housing to depress the core of a standard tire valve and permit the air pressure within the tire to be introduced into the chamber. A wall of the chamber is movable with changes of pressure and a piezoelectric crystal transducer or strain gauge transducer is mounted to be stressed in accordance with movement of this wall to develop an analog voltage in accordance with the air pressure. An electrical circuit is contained within the housing and energizable by a battery carried within the housing. A power switch is actuated to an on condition by movement of the gauge onto the tire valve to energize the electrical circuit with the analog voltage passed to an analog-to-digital converter and then to a digital readout display to display the digital value of the air pressure within the tire.

Abstract: A silicon transducer including a silicon frame with one or more lands extending from a diaphragm or the like. The lands are interconnected by two thin strips formed integrally with the lands. The strips are essentially the transducer. The transducer is constructed by etching a boron doped wafer with a mixture of catechol, ethylene diamine and water.

Abstract: A differential sensor unit precisely monitors ambient pressure within a confined space, such as blood pressure or intracranial pressure of a human patient, utilizing fiber optic light guides. Three light guides pass within a pneumatic line into one end of a rigid cylindrical envelope which may be inserted into a vein or artery or implanted in the skull. The other end of the envelope is bounded by a flexible membrane. Of the external ends of the guides, one faces a light source and each of the others faces a light detector. A reflective surface is attached to the internal face of the flexible membrane.

Abstract: A pressure detector comprising a spring-loaded diaphragm mounted in a housing to define a pressure chamber to which test fluid is introduced. A pulse generating element is provided to generate an electrical pulse in response to a displacement of the diaphragm when the fluid pressure in the pressure chamber exceeds a predetermined level. An averaging circuit is connected to the pulse generating element to convert the pulses into a signal having a voltage level representative of the mean value of the pressure variation.

Abstract: A pressure dome is provided with resilient tongues that engage projections on a transducer in such manner as to draw the dome and transducer together when one is rotated with respect to the other. Detent notches for the projection ensure that the force between a dome and the transducer is always the same.

Abstract: A probe for measuring the amplitude of high frequency pressure pulses in a high or low temperature fluid environment comprising a hollow housing structure having an open end covered by a flexible metallic diaphragm member. A transducer is located in the housing and is forcibly maintained in direct engagement with the diaphragm member. Pressure pulses in the high or low temperature fluid medium deflect the diaphragm member, which is in contact with the transducer, causing it to produce electrical signals representative of the pressure pulses impinging against the diaphragm member. These electrical signals are transmitted to electronic recording and analyzing equipment to provide an accurate reading of the sensed pressure pulses.

Abstract: This disclosure refers to an air pressure sensor using wafer thermisters and, in particular, an air pressure sensor considered indispensable for blood pressure measurement.

Abstract: A system and method is described for measuring fluid pressure force by immersing a solid mechanically resonant element into the pressure-bearing medium, exciting the solid mechanically resonant element to resonance, and observing changes in frequency with changes in fluid pressure. The advantage of the disclosed method lies in the high accuracy and resolution that the system permits when it employs for the solid mechanically resonant element a nearly perfect single crystal material since the method relies upon the bulk properties of the resonant material rather than upon other factors.

Abstract: A pressure responsive sender whose electrical resistance varies in response to variations in sensed pressure, adapted to be inserted in series with a voltage source and a pressure indicating gauge, such as an oil pressure indicating gauge. The sender includes a pressure sensing diaphragm coupled to a contact assembly which electrically engages a variable resistor assembly to an extent which is a function of the sensed pressure so that a predetermined electrical resistance for a particular sensed pressure is obtained. A dual stage spring system is associated with the pressure sensing assembly providing increased sensitivity in a low pressure range, a well-defined cut-off pressure and accurate calibration of the sender. The resistor and contact assemblies are pivotally mounted in a manner such that hysteresis problems, i.e., obtaining slightly different resistance values for identical pressures after cycling, are eliminated.