Abstract: An in-cylinder pressure sensing apparatus for a multi-cylinder engine has a plurality of sensing parts packaged between a cylinder head and a cylinder block of an engine having a plurality of cylinders and being operative to detect a signal indicative of an internal pressure of each of the plurality of cylinders. A detection circuit is provided for connecting the sensing parts in series and for overlapping detection signals obtained from the individual sensing parts to take out a resulting overlapped signal. A reference signal generator operates to supply a reference signal for separating detection signals corresponding to the individual cylinders from the overlapped signal. A unit is also provided for separating the detection signals, detected in accordance with pressures of the individual cylinders, from the overlapped signal on the basis of the reference signal.

Abstract: A sensor system for sensing a measurand field within an environment includes an optical source, such as a light emitting diode, for providing broadband light to an array of serially coupled sensor elements disposed within an optical fiber. Each sensor element includes a fiber grating (Bragg grating) which, when illuminated, reflects a narrow band of light having a specified central wavelength. The optical fiber is deployed in a high strength hermetically sealed capillary tubing structure. Within the capillary tube, at least in the area of the sensor elements, the capillary tubing is filled with a high-density, low-compressibility, and high thermal conductivity material, such as a liquid, which completely fills all of the void spaces within the capillary tubing between the tubing and the sensor elements such that compressive forces which are exerted on the external surfaces of the tubing are accurately transmitted to the sensor element.

Abstract: A fiber optic spark plug integrated combustion pressure detector comprises the sensitive sensor head with "snap" action diaphragm to provide the temperature insensitivity to combustion temperature variations. The optical module is integrated into the electrical connector to eliminate open optical interfaces. The "snap" action and special diaphragm shape selectively increase detector knock and misfire discrimination. The pressure sensor can be made spark plug integrated or injected in block cylinder for combustion pressure sensing in engine.

Abstract: A method and apparatus are provided for measuring pressure in a combustion chamber of an internal combustion engine is provided with a non-intrusive, metal-embedded fiber optic pressure sensor. A Fabry-Perot Interferometer is arranged in a terminated, single mode fiber to function as a pressure gauge. The fiber Fabry-Perot Interferometer (FFPI) is embedded in a metal part which is disposed in the cylinder head of the engine. The metal part and FFPI experience a longitudinal compression in response to the pressure in the chamber. In another aspect of the invention, a non-intrusive fiber containing the FFPI is embedded in a hole drilled or otherwise provided in the metal housing of a spark plug. The spark plug is threaded into the cylinder head of an internal combustion engine and is directly exposed to the combustion chamber pressure. Consequently, the spark plug housing and FFPI experience a longitudinal strain in response to the pressure in the chamber.

Abstract: A pressure port has a diaphragm at one end for exposure to combustion pressure, an electrical connector attached to the other end, terminal blades and a lead frame molded in the connector and carrying an optoelectronic circuit, and a fiber optic assembly between the circuit and the diaphragm. The fiber optic assembly illuminates the diaphragm which reflects light according to its deflection to two fiber elements that carry reflected light to the circuit. The assembly includes a high temperature plastic body and a ceramic tip for temperature isolation to protect the plastic body and the optoelectronic circuit.

Abstract: A physical quantity detecting apparatus comprises at least one optical fiber, at least one light emitting means for emitting an incident light beam on the optical fiber, at least one light receiving means for detecting an outgoing light beam from the optical fiber, physical quantity applied position information generating means for providing information indicative of a position of a portion at which a physical quantity is applied to the optical fiber, and operation means for receiving signals from the light receiving means and physical quantities applied position information generating means and calculating a change with time in physical quantity at respective positions on the optical fiber.

Abstract: A residual pressure sensor for verifying that a residual pressure is zero, and to a monitoring apparatus for monitoring for faults in the residual pressure sensor. In order to detect that a residual pressure has completely gone, the residual pressure sensor detects change conditions in the output therefrom, and an output for no residual pressure is not generated while there are changes. Moreover, an electrical power supply condition to a drive solenoid (21) of a solenoid valve for opening/closing a pressure supply line, is monitored using a fail-safe current sensor (21) which outputs a logic value "0" when the presence of a current is detected, and which outputs a logic value "1" when the presence of a current is not detected. Fault monitoring of the residual pressure sensor is then carried out based on the monitoring output conditions of the current sensor and the output conditions of the residual pressure sensor.

Abstract: A rigid plate with an aperture therethrough has a variable coupler fiber optic sensor encapsulated in the aperture by an encapsulant having an index of refraction that varies with applied stress. Incident light applied to an input fiber of the coupler is coupled to the output fibers thereof in a ratio dependent on the stress applied to the encapsulant. In an alternative embodiment, a well in a member superposed with respect to the plate is filled with a low bulk modulus material which abuts the encapsulant.

Abstract: The present invention concerns a device for monitoring the pressure in at least two pressure-tight analysis vessels, that have been sealed by means of lids, whereby heat is supplied to the analysis vessels by means of a heating apparatus. The internal pressure of the analysis vessel acts on its lid. The lid is connected to a piston in a closed hydraulic system. The force, that is dependent on the internal pressure of the analysis vessel, is transferred by the lid to the piston in the hydraulic system. A lid and a piston are assigned to every analysis vessel. In addition, a stop device is assigned to each piston, whereby the stop device limits the outward movement of the piston in the event of excess pressure in the hydraulic system relative to the internal pressure of the analysis vessel. The pistons are connected to one another via the hydraulic system.

Abstract: A pressure sensitive paint is coated onto the surface over which a pressure distribution is to be measured, such as in a wind-tunnel test of an aerodynamic body. A pressure sensitive paint is a mixture of a photoluminescent-compatible, oxygen-permeable binder that is a mixture of silanol-terminated polydimethylsiloxane and methyltriacetoxysilane, and a photoluminescent active agent such as tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride pentahydrate. The binder and active agent are placed into an appropriate amount of a solvent for the binder and the active agent, such as dichloromethane, and applied to a surface. In testing of the surface such as wind tunnel testing, the active agent quantitatively luminesces responsive to the local external pressure at the surface.

Abstract: The invention relates to an optical pressure detector for instance in the form of an optical alarm with a multimode light guide (1) imbedded in a contact pad (2) subject to pressure, said light guide being curved by the compression of the contact pad (2). The light guide (1) is mounted between a light source and a light detector, an analyzer being present to analyze the output signals from the light detector changing through mode coupling as a function of the applied pressure, and to process them for instance into an alarm signal. The light detector covers an angle of aperture at the exit of the light guide (1), said angle only enclosing the radiation field in the range of lower-order modes of the light guide (1).

Abstract: An in-line pressure transducer includes a body and an inner ring, coupled to the body, through which molten material flows. The inner ring expands in response to pressure from the molten material. An outer ring is located coaxially with the inner ring. At least one flexure connects the inner and outer rings. The flexures translate expansion of the inner ring to the outer ring. The body includes a cavity within which the outer ring is located. The cavity preferably has a cross-sectional shape that is trapezoidal in order to compensate for lateral displacement of the transducer in response to axial forces exerted thereon during operation.

Abstract: A differential pressure transducer is provided in which first and second diaphragms are formed within a block of material, such as monocrystalline silicon. Each diaphragm carries a support for a bridge. The supports are offset from the center of the diaphragms such that deflection of the diaphragms imparts a degree of lateral motion to the respective support. The bridge is held within an evacuated cavity and the resonant frequency of the bridge is a function of the difference in pressure action of the diaphragms.

Abstract: A vibrating element transducer is provided in which a vibrating element and a substantially non-vibrating reference element are positioned side by side and illuminated via an optical fibre. The surfaces of the vibrating element and the reference element are formed at slightly different distances from the end of the optical fibre. The differing distances are arranged such that interference between the light reflected from the vibrating element and from the reference reflector can be used to determine the frequency of vibration of the vibrating element.

Abstract: A system for characterizing the pressure, temperature, movement and flow patterns of a fluid under high pressure within a test cell. The test cell is lined internally with adjustable rock facings. Pressure is measured within the test cell using a device employing pressure-distortable optical fibers. Fluid velocity, flow direction, and filter-cake buildup are measured with laser Doppler velocimetry. The flow pattern of the fluid is viewed using corresponding arrays of transmitting and receiving optical fibers. Temperature of the fluid is estimated using a combination of thermal sensors. The pressure, velocity, viewing and temperature systems are integral to the rock facings of the test cell.

Abstract: A pressure transmitter converts input pressures on the order of 0.000.15 inch of water column to proportional electrical output signals. A housing defines an open internal chamber and a substantially constant area shaped membrane spans the chamber and is secured about its perimeter thereto, dividing it into a convex side and a concave side. The convex side of the membrane forms an input side adapted to receive an input pressure. A beam is mounted for pivotal movement on the concave side of the membrane. One end of the beam supports a mechanical column which contacts the membrane and asserts a slight upward force on it. The opposite end of the beam mounts a reflector which is mounted directly over a photomicrosensor which outputs a voltage signal proportional to the movement of the reflector. A second photomicrosensor outputs a constant reference output voltage. A comparator receives both photomicrosensor outputs and outputs a voltage signal proportional to the difference therebetween.

Abstract: A first surface of a diaphragm is exposed to high temperature gas in the combustion chamber of an internal combustion engine. The curvature of the diaphragm changes in response to the gas pressure. Three optical fibers are spaced along a radius of the diaphragm and have ends which face a second surface of the diaphragm. A light source injects light into a center fiber, which is displaced from the center of the diaphragm by a predetermined distance. Outer fibers receive light from the center fiber after reflection from the diaphragm. The relative intensities of light reflected from the diaphragm into the outer fibers correspond to the curvature of the diaphragm and thereby to the pressure. The outer fibers have a larger numerical aperture than the center fiber, and the light source fully populates all of the optical modes of the center fiber to reduce modal noise caused by physical perturbation of the fibers. The fibers preferably have a square cross-section to maximize linearity.

Abstract: A microsensor for application in measurements of pressure including a temperature compensated vibratory bar comprises means for measuring the resonance frequency of the vibratory bar, means for measuring the temperature by interferometric determination of the optical thickness of the bar and means for determining a physical quantity to be measured based on resonance frequency and temperature.

Abstract: A gas density sensor having a prism in contact with a fluid whose density is determined. A light source shines light into the prism. The light is reflected off prism surfaces in contact with the fluid. As the fluid density changes, the amount of light reflecting off these surfaces changes depending upon fluid density. A detector placed to receive light reflecting off the surfaces determines density from sensed light.

Abstract: A pressure transducer for an injection molding machine includes a housing coupled to a nozzle of an injection molding machine. A hollow stress tube, attached to the housing, through which molten material of the injection molding machine flows, bellows in response to pressure from the material. An outer ring having an opening is coupled to the stress tube such that the outer ring expands, causing displacement of the outer ring about the opening, when the stress tube bellows. A displacement sensor is included for determining the displacement of the outer ring about the opening. This displacement is directly proportional to the pressure of the material. In this manner, the pressure transducer determines the pressure of the molten material.

Abstract: An improved fiberoptic pressure sensing system is disclosed by tapering the tip end of an optical fiber, or alternatively, by tapering or bundling a fiber or group of fibers within a connector. By selectively joining together fibers with a taper while tailoring numerical apertures of the connected fibers, a fiberoptic pressure sensing system is provided with an enhanced ability to increase sensitivity and signal-to-noise performance.

Abstract: A fiberoptic fluid pressure transducer system involving a thin flat diaphragm, fiberoptic elements, a tubular member having an opening of fixed dimensions on the side thereof, an L-shaped cantilevered beam and a remotely located electronic control unit. The cantilevered beam has one leg horizontally attached to a recessed ledge surrounding the opening such that a vertical leg extending from the horizontal leg, including a light reflector, extends into the opening. A diaphragm covers the opening and makes physical contact with the horizontal leg of the L-shaped beam. Pressure applied to the diaphragm flexes the horizontal leg of the beam which, in turn, causes a spatial displacement of the vertical leg with respect to the fiberoptic elements. The resulting change in reception of the reflected light is proportional to the pressure applied to the diaphragm or membrane. The sensitivity of the transducer can be altered and the system can have two or more levels of sensitivity over a range of pressure measurements.

Abstract: A pressure sensor for connection to a transmission optical fiber which allows the transmission of a light beam. The pressure sensor comprises a material which is essentially elastic to deformation and optically transparent to the wavelengths of light used. The material includes at least two inclusions, each comprising an optical fiber segment. The distance between the inclusions varies when a deformation is exerted on the pressure sensor. This, in turn, modifies the focal length of the optical system defined thereby, and leads to a variation of the light energy collected by a transmissive optical fiber. The pressure sensor is suitable for detectors or measuring devices for medical use, and in this regard, a method for measuring blood or respiratory pressure is also provided.

Abstract: A washer configuration fiber optic sensor comprising radial ridges in the cavity between the washer halves and an optical fiber spiralled to a terminating end within the cavity. The terminating end is mirrored and an optical filter is inserted in the fiber path adjacent the fiber entrance to the washer. Changing compression loads on the washer microbend the fiber and modulate the measuring light beam admired to the fiber and reflected back through the fiber. The optical filter is located in a connection between the washer and a transmitting fiber. The transmitting fiber both delivers light to the washer and collects light back from the washer. The connector is configured to deliver the measuring light beam to both the core and cladding of the fiber in the washer. However, the connector is configured to strip away the portion of the reflected light beam otherwise delivered to the cladding of the transmitting fiber. A reference light beam of differing wavelength is reflected by the filter.

Abstract: A force sensor and a force sensing method use crystal rods as both force responsive elements and light transmission media in combination with light input circuitry and processing circuitry to sense an applied force, such as oil or gas well pressure or fluid flow friction.

Abstract: A differential pressure transducer cell comprises a housing and a pair of spaced diaphragms connected at one end to one portion of the housing and connected at an opposite end to a second portion of the housing. The diaphragms have an outer surface and an inner surface; and the outer surface of each diaphragm is exposed to a pressure. A beam is connected between the diaphragms at the inner surface of the diaphragms. Sensors are also provided on the beam.

Abstract: The invention is related to numerous improvements for fiber optic measuring systems, and principally those utilizing a deformable diaphragm for sensing pressure. One feature of the invention is particularly oriented to automotive engine combustion chamber pressure measurement. For that application, a sensing tip shielding technique is described using a sintered metal porous plug, which reduces temperature fluctuations experienced at the sensing tip and shields the sensing tip from corrosive materials. A technique for compensation of a fiber optic pressure sensor is also described. In that method, a referencing wavelength is partly reflected and partly transmitted past a filter coating at the sensing end of the optical filament. This technique of the sensor provides improved calibration.

Abstract: The optical sensor includes a support (2), an optical fiber (15) and two elements (9, 10) mounted on the support (2) in such a manner as to move as a function of the variations of a quantity to be measured, such as pressure. The attenuation of an optical radiation in the optical fiber (15) deformed by reverse bending is measured. The support (2) is constructed in the form of a bending beam including two end parts (2b, 2c) bearing on two fixed abutments and a central part (2a) connected to a metal membrane (16) actuated as a function of the variations of the quantity to be measured. The optical fiber (15) is disposed between the two movable elements (9, 10) in the form of a comb, each fixed on an end part (2b, 2c) of the support. The elements (9, 10) include active surfaces coming into contact with the fiber (15) to produce a variable reverse bending of the fiber (15) in the course of their relative movement.

Abstract: A pressure transducer comprises a polycrystalline diamond diaphragm (39), produced by use of a chemical vapour deposition technique, on a support (33). The diaphragm (39) can deflect in response to variations in pressure. A single optical fibre interferometer (36, 32) is used for detecting and measuring the deflection of the diaphragm (39) (FIG. 3).

Abstract: A pressure transducer for an injection molding machine includes a housing coupled to a nozzle of an injection molding machine. A hollow stress tube, attached to the housing, through which molten material of the injection molding machine flows, bellows in response to pressure from the material. An outer ring having an opening is coupled to the stress tube such that the outer ring expands, causing displacement of the outer ring about the opening, when the stress tube bellows. A displacement sensor is included for determining the displacement of the outer ring about the opening. This displacement is directly proportional to the pressure of the material. In this manner, the pressure transducer determines the pressure of the molten material.

Abstract: A coating material for wind tunnel luminescent barometry of surfaces such as airfoils and airframes uses a resin such as poly[1-(trimethylsilyl)propyne], or a siloxane polymer, to carry a pressure indicator. The pressure indicator may be photoluminescent ruthenium complex, such as [Ru(Ph.sub.2 phen).sub.2 ]Cl.sub.2, a photoluminescent platinum complex, such as PtOEP, and photoluminescent mixtures of pyrene and perylene.

Abstract: To measure pressure acting on a support (1), a sealed bag (2) which is filled with a fluid and has flexible bag walls (9, 10), and which is arranged on the support (1) and whose interior communicates with a flexible capillary tube (4, 4'), is used as a sensor. Connected to the free end of the flexible capillary tube (4, 4') is an evaluation device which detects pressure variation, it being possible for the end of the flexible capillary tube (4, 4') to be plugged into a block (5). The block has a bore (6) which continues the channel of the flexible capillary tube (4, 4') and is sealed at its end not: subjected to the flexible capillary tube (4, 4') by a diaphragm (7). The diaphragm bulges outwards in the event of a reduction in the volume of the bag (2). The extent of the outward bulging of the diaphragm (7) can be determined by an optical detector (15, 16).

Abstract: An optical pressure transducer includes a body for supporting therein both an input optical fiber and an output optical fiber. A light source generates input light to the input optical fiber. A force responsive diaphragm is secured to the body and deflects in response to sensed pressure. A fixed reflector and a moveable reflector, which is attached to and moves with the diaphragm, are disposed in the optical path between the input and output optical fibers and reflect at least a portion of the input light from the input optical fiber to the output optical fiber. The amount of light reflected depends upon the deflection of the diaphragm. A system for monitoring and controlling the light source, including an optical detector in a feedback arrangement, is provided such that the amount of light generated by the light source remains constant and maximized.

Abstract: An optical fiber pressure sensing catheter and a method for using such for detecting a discrete pressure within an organ such as an esophagus. The catheter comprises an elongated hollow body having a wall, a closed proximal end, a closed distal end, and a lumen therebetween. The wall is generally noncompressible by pressure normally exerted thereupon by the organ within which the catheter is inserted except for at least one discrete sensing area of the wall having sufficient flexibility so as to be compressible by pressure exerted thereupon by the organ within which the catheter is inserted. The catheter further comprises at least one sensing optical fiber disposed within the lumen. The optical fiber further comprises a pressure sensing means which is a portion of the optical fiber adjacent the discrete sensing area of the wall. The sensing portion is deformable in response to compression of the discrete sensing area of the wall, which deformation causes attenuation of light transmitted through the fiber.

Abstract: A detector tube is supplied with air at an adjustable pressure balanced by at least two adjustable leak flow rates in the conduits 4 and 7 in order to adjust the position of ball in the tube. The possible manual inclination of tube between an extreme vertical position and position slightly inclined to the horizontal is a complementary means of adjustment. The detector tube can be used for the detection and measurement of micropressures and micro flow rates.

Abstract: A system for characterizing the pressure, temperature, movement and flow patterns of a fluid under high pressure within a test cell. The test cell is lined internally with adjustable rock facings. Pressure is measured within the test cell using a device employing pressure-distortable optical fibers. Fluid velocity, flow direction, and filter-cake buildup are measured with laser Doppler velocimetry. The flow pattern of the fluid is viewed using corresponding arrays of transmitting and receiving optical fibers. Temperature of the fluid is estimated using a combination of thermal sensors. The pressure, velocity, viewing and temperature systems are integral to the rock facings of the test cell.

Abstract: An optical pressure transducer includes a body for supporting therein both an input optical fiber and an output optical fiber. A light source generates input light to the input optical fiber. A force responsive diaphragm is secured to the body and deflects in response to sensed pressure. A fixed reflector and a moveable reflector, which is attached to and moves with the diaphragm, are disposed in the optical path between the input and output optical fibers and reflect at least a portion of the input light from the input optical fiber to the output optical fiber. The amount of light reflected depends upon the deflection of the diaphragm. A system for monitoring and controlling the light source, including an optical detector in a feedback arrangement, is provided such that the amount of light generated by the light source remains constant and maximized.

Abstract: An electromagnetic fluid pressure transducer is provided which uses the opposing magnetic fields of a permanent magnet and an electromagnet to sense a change in a differential force. The differential force is the result of a pressure applied to the unequal surface areas of two pistons attached to opposite poles of the permanent magnet. The differential force displaces the permanent magnet which activates a counter whose output controls the field strength of an electromagnet. The magnetic field of the electromagnet is varied by the counter output to counterbalance the differential force by interacting with the field of the permanent magnet. The field strength of the electromagnet is varied until the magnetic force is sufficient to overcome the differential force and return the permanent magnet to its original position which stops the counter. As a result, the counter output which changes in proportion to change in the ambient pressure acting against the pistons can be used to indicate pressure.

Abstract: A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P).

Abstract: Differential displacement is optically detected by independent movement of either a collimated light source or a dual element photosensitive detector. Relative movement between the detector or light source generates a signal proportional to the amount of light striking the photosensitive elements. This invention relates to improved devices for the transformation of physical forces into mechanical and electro-optical response, for measuring the forces involved, and, in particular for wet/wet liquid and gas differential, gage and absolute, pressure measurements.

Abstract: A luminescent pressure sensitive composition for determining an air pressure pattern includes a binder, preferably a polymer binder, with a luminophore, of which the intensity of luminescence depends on air pressure. The luminophore of which the intensity of luminesence depends on air pressure (active luminophore) is mixed together with an additional luminophore of which the intensity of luminescence has a different dependence on air pressure than the active or reference luminophore.

Abstract: A sensing and displaying system is provided including a sensor unit having a transducer disposed in intimate contact with a vessel. The transducer senses a characteristic within the vessel like pressure and outputs an electrical signal representative thereof. The sensor unit further includes a response signal generator which transmits a signal representative of the characteristic. A receiver unit receives the transmitted signal and converts it to visual indicia of the characteristic, for example, a number on a liquid crystal display. The system is capable of two-way communication between the sensor unit and the receiver unit. Both the sensor unit and receiver unit store transmitted data in internal memory.

Abstract: A device for manometric measurement of the oesophagus has a catheter with a pressure sensor and a recording unit with a light source for monochromatic and coherent light, and a counting unit for light pulses. The pressure sensor is constructed as a Fabry Perot measuring section and has a pliable optical fiber embedded in elastic base material. The optical fiber is connected via a fiber-optic light guide to the recording unit (3). One end (6) of the optical fiber (5) is metal-coated and the other end (7) is partially metal-coated and connected to the fiber-optic light guide (8). The fiber-optic light guide (8) conveys not only the light from the light source to the optical fiber but also the light pulses from the optical fiber to the counting unit.

Abstract: A sensor for use in an optic system to detect current conditions in an environment. The sensor has a crystal member with a first waveguide extending from a top surface and a second waveguide extending from a bottom surface of a core member. Polarized light waves from a source are simultaneously communicated to the first and second waveguides. A first pressure is communicated to the top surface of the crystal member and an unknown pressure corresponding to the pressure of the environment is communicated to the bottom surface of the crystal member. The first pressure and the unknown pressure develop a pressure differential which acts on the crystal member to deform the first and second waveguides. The deformation of the first and second waveguides modifies the polarized light waves to create first and second output waves which are communicated to an optical interface where differences therebetween are extracted.

Abstract: The invention is related to numerous improvements for fiber optic measuring systems, and principally those utilizing a deformable diaphragm for sensing pressure. One aspect of the invention is providing temperature compensation for diaphragm characteristics. Temperature measurement can be achieved by using a light signal having a wavelength distribution which overlaps the cut-off characteristics of a filter positioned at the fiber sensing end. Shifting in the cut-off characteristic in response to temperature modulates the intensity of the reflected back temperature compensation signal. In another approach, temperature is measured through its differential effect on light signals having different launching conditions. With either approach, the temperature measurement is used to calibrate the output of the pressure sensitive diaphragm.

Abstract: A tire pressure and temperature monitoring system for measuring tire inflation pressure and anomalous temperature of rotating tires in a moving vehicle by means of optoelectronic devices located in the stationary structure of the vehicle and an elastic diaphragm that rotates with the wheel and tire. The combined use of optoelectronic components and elastic diaphragms, provides a marked improvement in performance, reliability and cost over previously disclosed magnetic or radio frequency pressure measurement systems. The optoelectronic detector elements are also used to identify those tires whose side wall temperature is significantly higher than the side wall temperature of the other tires. In addition, the system can also be used as a measurement of individual wheel rotational speed and related wheel motion.

Abstract: A system for characterizing the pressure, temperature, movement and flow patterns of a fluid under high pressure within a test cell. The test cell is lined internally with adjustable rock facings. Pressure is measured within the test cell using a device employing pressure-distortable optical fibers. Fluid velocity, flow direction, and filter-cake buildup are measured with laser Doppler velocimetry. The flow pattern of the fluid is viewed using corresponding arrays of transmitting and receiving optical fibers. Temperature of the fluid is estimated using a combination of thermal sensors. The pressure, velocity, viewing and temperature systems are integral to the rock facings of the test cell.

Abstract: An optically driven microresonator sensor comprising a sensor member having a vibratory bridge onto which a light beam is directed at a non-zero angle relative to a normal to said bridge, the light beam causing the bridge to oscillate at its resonant frequency, in use, in the direction of said normal, between a first position, where most of the incident light is reflected by the bridge to a light intensity measuring system, and a second position, where most of the incident light is not intercepted by said bridge, so that the reflected incident light sensed by said light intensity measuring system is reduced, the resonant frequency of oscillation of the bridge thus determined from said system, being dependent upon the nature of an applied force, such as stress, exerted on the sensor member.

Abstract: A differential pressure sensor with a compensation means, said differential pressure sensor comprising the diaphragm with a first means having a mass mounted upon the diaphragm. The first means is utilized to determine the position of the diaphragm relative to an initial first position and/or to increase the effective area of the diaphragm. A housing contains the diaphragm, the housing has a first and a second inlet port. The first inlet port provides a first pressure to a first side of the diaphragm and the second inlet provides a second pressure to the second side of the diaphragm, the diaphragm moving to the lesser of the two pressures. A counterweight mechanism is located in the housing having a inner arm and an outer arm. The counterweight mechanism pivots about an axis. The center of gravity of the counterweight mechanism is located on the outer arm.

Abstract: A differential pressure sensor utilizing an opto-reflective sensor comprising a diaphragm with a top and a bottom, the diaphragm having an optical reflector mounted upon it. The diaphragm is mounted in a housing, wherein the housing has a first inlet port and a second inlet port, the first inlet port providing a first pressure to the top of the diaphragm and the second inlet port providing a second pressure to the bottom of the diaphragm. An opto-reflective sensor is mounted in the housing, wherein the opto-reflective sensor provides an optical signal to the optical reflector. The optical reflector reflects the signal back to the opto-reflective sensor, wherein the differential pressure sensor calculates the distance of the optical reflector from the opto-reflective sensor in relation to the relative intensity of the reflected optical signal.