[go: up one dir, main page]

EP0224575A1 - Capteur optique de pression - Google Patents

Capteur optique de pression

Info

Publication number
EP0224575A1
EP0224575A1 EP19860903974 EP86903974A EP0224575A1 EP 0224575 A1 EP0224575 A1 EP 0224575A1 EP 19860903974 EP19860903974 EP 19860903974 EP 86903974 A EP86903974 A EP 86903974A EP 0224575 A1 EP0224575 A1 EP 0224575A1
Authority
EP
European Patent Office
Prior art keywords
diaphragm
interface
sensor
light
medium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19860903974
Other languages
German (de)
English (en)
Inventor
Robert W. Hoffman
Jack A. Ekchian
Leon Ekchian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Optima Systems Inc
Original Assignee
Optima Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Optima Systems Inc filed Critical Optima Systems Inc
Publication of EP0224575A1 publication Critical patent/EP0224575A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
    • G01L9/0076—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means
    • G01L9/0077—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means for measuring reflected light

Definitions

  • the invention relates generally to the field of pressure measurement and in particular to rugged pressure transducers for use in environments of widely fluctuating temperature and pressure.
  • the invention is specifically directed to automotive applications, uses in fields other than automotive, such as petroleum recovery and process control, are actively contemplated.
  • the present invention is motivated by a long felt need to indicate instantaneous pressure inside the combustion chamber of an internal combustion engine with a reliable, inexpensive device. Optimization of the performance and emission characteristics of internal combustion engines is of vital national importance. In 1981 automobiles in the United States used approximately thirty percent of all petroleum 'based fuels consumed and contributed as much as fifty percent of the hydrocarbons and oxides of nitrogen discharged into the atmosphere nationwide. It is recognized by researchers in the automotive industry that instantaneous pressure of the gases in the combustion chamber of an internal combustion engine, if measured and interpreted properly, yields data concerning combustion and flow processes in the cylinder which can be fed into a microprocessor-based engine control system to improve efficiency and reduce emissions. The benefits to be derived include optimized automatic spark timing, increased knock limit and improved self-test and diagnostic capability.
  • the internal comb.ustion chamber presents a hostile environment of electromagnetic noise and sharp fluctuations in temperature and pressure. Pressures and temperatures can be highly stochastic, varying from near ambient conditions to more than 70 atmospheres and 2000°C, respectively. Fluctuations between these extremes occur at a rate of 30 to 40 times per second in a typical automobile engine cylinder. There are no accurate, reliable low cost transducers currently available for combustion chamber pressure monitoring despite widespread agreement among the internal combustion engine research community, both in industry andTECH, that the measurement of pressure in the combustion chamber is extremely valuable both as a diagnostic and control parameter.
  • Cylinder pressure transducers used today by laboratory scientists are almost exclusively of the piezoelectric variety. While piezoelectric transducers have excellent frequency response and can withstand moderate high temperatures and pressures in the combustion engine, they exhibit a number of disadvantages, namely, high cost, sensitivity to high temperatures, charge leakage and sensitivity to electrical noise.
  • Two other types of pressure transducers which have been successfully used by researchers, although not applied in commercial practice, are the balanced pressure indicator and the strain gage transducer. In the balanced pressure indicator a diaphragm reacts to relative cylinder pressure to close an electrical contact. Balanced pressure indicators have been largely abandoned by researchers because they only generate two pressure readings per cycle and have significant time delays.
  • Strain gage transducers ope ate by mechanically deforming a variable resistance element usually arranged in an electronic bridge circuit. Typical strain gages exhibit temperature gradient sensitivity, creep, nonlinearity and poor bandwidth.
  • the invention harnesses an optical phenomenon known as frustrated or attenuated total internal reflection as a means of sensing pressure.
  • the result is a transducer with essentially no moving parts, insensitivity to electromagnetic interference, excellent frequency response and thermal stability.
  • a light beam, preferably modulated is introduced into a transparent medium with an internal reflection boundary preferably via an optical fiber.
  • the internally reflected light ray is carried to a detector such as a photocell preferably via a second optical fiber.
  • a diaphragm juxtaposed with the reflection boundary is deflected under pressure and moves closer to or farther from the surface of the transparent medium to cause a change in the amount of light reflected which is defected by the light detector and translated into a pressure signal.
  • the intruding surface of the diaphragm facing the reflection boundary of the transparent medium is composed of a reflective material, preferably metal.
  • the intruding surface causes attenuated total reflection (ATR) as opposed to frustrated total reflection (FTR).
  • ATR attenuated total reflection
  • FTR frustrated total reflection
  • the transparent medium is a thin disc of glass supported inside a metal cylinder with a closed end.
  • the cylinder is threaded like a spark plug and the closed end is formed by a thin metal or ceramic diaphragm exposed to the internal combustion chamber.
  • the diaphragm is formed integrally with the chamber wall by boring a cylindrical hole in an engine block or other pressure vessel, leaving a thin piece of metal forming the diaphragm between the pressurized chamber and the bore, and then inserting the optical head comprising the cylindrical fiber holder and glass disc.
  • a central cylindrical boss is formed on the inner surface of the diaphgram adjacent to the transparent medium at the point where reflection occurs.
  • the face of the boss is preferably coated with a highly reflective metal or metal alloy to induce attenuated total reflection.
  • a preferred method of manufacturing an ATR device is to apply a soft reflective metal coating, preferably gold or platinum, to the face of the boss on the diaphragm and to force the surface of the glass disc and boss together by overpressuring the exposed side of the diaphragm, thereby flattening the metal coating.
  • a preferred way of carrying out this method is to first overpressure the diaphragm and then while maintaining the overpressure condition, forcing the optical head against the coated boss with a known force and simultaneously bonding the optical head in place. When the pressure is released, the diaphragm resumes its normal position leaving a predetermined uniform gap width between the precisely parallel faces of the coated boss and transparent medium.
  • a third fiber or other light pickup means can be arranged to receive dispersed input light which falls outside the region juxtaposed with the boss to form a reference signal not affected by gap width.
  • a second pickup can be arranged to tap into- the input fiber directly, or a second pair of input and output fibers can be arranged as a reference.
  • the transmission or filtered reception of selected wavelengths can be employed to yield a ratio which is affected by gap width but substantially unaffected by amplitude and coupling factors.
  • FIG. 1 is a sectional view of an optical pressure sensor for an internal combustion chamber according to the invention.
  • FIG. 2 is a cross-sectional view of the sensor of Fig. 1 taken along lines 2-2.
  • FIG. 3 is a partial sectional view through the diaphragm of Fig. 1 showing an alternate embodiment thereof.
  • FIG. 4 is a partial sectional view similar to that of Fig. 3 showing another alternate embodiment of the diaphragm of Fig. 1.
  • FIG. 5 is a sectional view of another embodiment of the optical pressure sensor according to the invention.
  • FIG. 6 is a graph comparing frustrated and attenuated total internal reflection.
  • FIG. 7 is a graph of pressure versus crank angle in an internal combustion chamber comparing a prior art sensor with an optical transducer constructed according to the invention.
  • FIGS. 8-12 are schematic perspective views of respective alternative embodiments with means to eliminate the effects of amplitude and coupling variations and drift.
  • FIG. 13 is a sectional schematic view of a sensor similar to that of Fig. 1 with a soft reflective metal coating on the face of the boss of the diaphragm being forced against the glass.
  • FIGS. 14A, 14B and 14C are sectional schematic views illustrating respective stages of a preferred assembly technique for the optical head and diaphragm of the optical pressure sensor according to the invention.
  • FIG. 15 is a sectional schematic view of an embodiment of the optical pressure sensor according to the invention where the diaphragm is integral with the chamber wall.
  • Fig. 1 shows a sensor designed to indicate pressure in an internal combustion engine.
  • a cylindrical metal housing 10 includes a disk-shaped recessed, integral metal diaphragm 12 at one end. The outer surface 12a of the diaphragm 12 is exposed to the pressures inside the combustion chamber. Housing 10 is externally threaded so as to be sealingly received, diaphragm end fir,st, through a threaded bore (not shown) in the engine block like a spark plug.
  • a coaxially mounted cylindrical block or fiber holder 16 carries a pair of converging optical fibers 18 and 20.
  • the fiber holder 16 may be made of various materials including ceramic material. For example, a powdered ceramic may be molded with the necessary holes for fibers 18 and 20 and then fired.
  • the fibers may be oriented in the fiber holder material before firing.
  • the lower surface 16a of the fiber holder 16 is ground flat with the ends of the fibers 18 and 2U exposed on the surface.
  • a thin coating of glass 22 is applied directly over the fiber holder surface 16a covering the ends of the fibers 18 and 20 to form a glass disk.
  • the preferred thickness of the glass disk is on the order of one millimeter.
  • the converging ends of the fibers 18 and 20 are oriented such that light generated by a modulated light source 24 introduced into the glass disk 22 via input fiber 18 is totally internally reflected at point 26 on the air/glass interface surface 22a of the glass disk 22.
  • the point of reflection 26 ideally lies on the axis of the cylindrical housing 10, and the axes of the proximal ends of fibers 18 and 20 lie in a plane including the cylindrical axis.
  • Light source 24 may be a light emitting diode or incandescent bulb or any other light source although coherent radiation from a laser may be preferable in certain applications.
  • the reflected light is collected via output fiber 20 which has its proximal end aligned with the axis of the reflected ray.
  • Diaphragm 12 is formed with a preferably integral, cylindrical boss 12b projecting coaxially toward the surface 22a of the glass disk 22 at the reflection point 26.
  • the variable gap 30 between the face of the cylindrical boss 12b and the opposing ⁇ surface 22a of the glass disk should be on the order of one wavelength of light.
  • the face of the cylindrical boss 12b is highly polished to achieve the desired flatness and parallel relationship with the opposed surface of the glass disk 22. The two surfaces that face each other should be polished to attain an extremely fine surface finish on the order of one quarter wavelength or better.
  • a metal diaphragm 12' has a ceramic coating 34 facing the high pressure environment and a light absorbing coating of glass or quartz 36 on the face of the cylindrical boss 12b 1 .
  • the entire diaphragm 12' ' is formed of a ceramic material with the face of the cylindrical boss being, coated with a light reflecting metal layer 37.
  • the active face of the boss 12b of the diaphragm 12 may be coated with a reflective metal layer of gold, platinum silver, copper or beryllium copper, for example.
  • the active face of boss 12b is coated with a reflective metal layer 37 using techniques known to those skilled in the art including electroplating, chemical vapor deposition, electroless or chemical plating, liquid dynamic compaction or other means for depositing a thin metal layer of predetermined thickness on either a metal or a ceramic substrate.
  • the metal coating 37 is preferably a highly reflective metal or metal alloy with a melting point in excess of the temperatures associated with the pressurized chamber or cylinder walls. For example, silver, gold, copper and brass all have m.p. of 90 ⁇ °C to 1100°C. Steel has a m.p. of approximately 1400-150 ⁇ °C.
  • the metal coating 37 usually requires polishing or smoothing to form a good reflecting surface.
  • a soft metal such as gold, platinum, silver, copper, aluminum, brass or zinc, having a hardness in the range of 2 to 4 on the Mohs scale (Handbook of Chemistry & Physics, 66th Ed. , page F19, (CRC Press, Inc. 1985)
  • the surface can be flattened and smoothed by overpressuring the the diaphragm 12' , as shown in Fig. 13.
  • Pressure in the range of approximately 1000 psi is normally exerted on the underside 12a of the diaphragm 12. Applying a pressure of 1200 psi or more forces the diaphragm upwardly towards glass disc 22, forcing the soft metal coating 37 against the glass disc 22 to flatten the coating.
  • FIGs. 14A, 14B and 14C An overpressure technique which eliminates the criticality of gap width measurements during assembly is shown in Figs. 14A, 14B and 14C.
  • the optical head comprising the fiber holder 16 and oonded glass disc 22 is inserted into the cylindrical housing 10' so that the central portion of the glass disc 22 abuts against the soft reflective metal coating 37 on the face of the boss 12b'. A predetermined force is applied to the top of the fiber holder 16.
  • the force applied to the optical head is sufficient to compress and flatten the surface coating 37 on the boss 12b' .
  • the optical head is affixed to the housing 10'.
  • the fiber holder 16 is made of metal, it may be affixed to the housing 10' by welding at the outer interface 13 as shown in Fig. 14B. If the fiber holder 16 is nonmetallic, an adhesive may be applied before insertion to the cylindrical sidewall -of the fiber holder 16 and activated by microwave or radio frequency electromagnetic energy to bond the optical head in position. After the optical head is affixed to the housing 10' , the pressure is released as shown in Fig.
  • Figs. 14A, 14B and 14C can accommodate batch processing by mounting a plurality of sensors through respective openings in a single pressure vessel, inserting the optical heads and forcing them down collectively against their respective diaphragm bosses with a common source of pressure. This technique would enable mass production without having to establish gap width by direct gauging. The technique is also amenable to automated assembly.
  • fiber holder 16 can be formed of a metal block with drilled holes, on the order of 0.39 inch for plastic optical fibers, for example.
  • a separate glass disk 22 can be epoxied directly to the active surface of the fiber holder 16. The optical coupling between the fibers 18 and 20 and the disk 22, however, are improved by bonding the glass layer 22 directly to the fiber ends as shown in Fig. 1 by applying the glass to the fiber holder in the molten state, or by sputtering or other vacuum deposition techniques.
  • FIG. 5 An alternate configuration of the pressure transducer according to the invention is shown in Fig. 5.
  • the fiber holder block 16' is metal with drilled holes accommodating fibers 18 and 20.
  • a glass disk 22 is bonded to the surface of the fiber holder 16' .
  • a separate cylindrical end plug 38 is mounted in spaced coaxial alignment with the disk 22 and fiber holder 16' inside a coaxial tubular sheath 40.
  • the closed upper end of cylindrical plug 38 forms diaphragm 12 with a cylindrical boss similar to boss 12b in Fig. 1.
  • the lower end of plug 38 is open and has an outside annular- groove 38a permitting, the protruding end of the plug 38 to be tightly clamped to a source of pressure to be tested.
  • the pressure vessel for example an engine casing (head or block) 50 is machined with a bore 52 extending inwardly towards the inner chamber wall 54, stopping just short of the pressurized chamber.
  • the thin metal section remaining forms the sensor diaphragm 56 as well as an integral portion of the chamber wall.
  • the optical head 60 consisting of a coaxially-mounted cylindrical fiber holder 62, carrying a pair of converging optical fibers and a thin glass disc 64 is sealingly received, glass face first, through bore 52 in the pressure vessel 50.
  • a boss 56a can be machined and coated with a soft metal and finished as described with reference to Fig. 13, 14A, 14B and 14C. Alternately, the boss 56a, coated or uncoated, may be polished to present a flat, reflective surface.
  • an increase in the pressure being tested loads the diaphragm and causes it to deflect toward the glass disk 22 thus narrowing the gap 30 between the opposed parallel faces of the glass disk 22 at the point of reflection 26 and the juxtaposed face of the cylindrical boss 12b (Fig. 1).
  • a deflection range of only two microns is sufficient as shown in Fig. 6 to achieve a sizeable variation in the amount of reflected light.
  • the output of light detector 28 is a function of the diaphragm deflection which is in turn a function of the pressure inside the pressurized chamber.
  • ATR has an advantageous, minimum reflectivity at about a half wave length spacing between the interface and the intruding surface.
  • FTR requires contact for extinction of reflection, but has an advantage in that a particular reflectivity corresponds to a single spacing.
  • ATR is preferred although the material requirements are somewhat more difficult.
  • ATR requires a reflective metal such as gold, platinum, silver, copper or beryllium copper.
  • the layer 37 would be one of these metals.
  • FTR could be accomplished with a quartz layer (e.g., 36 in Fig. 3) forming the extraneous light absorbing face on the diaphragm.
  • Figs. 8-12 illustrate variations which work on the same principle as that of the basic transducer shown in Fig. 1.
  • the added advantage of each of these variations is that they take into account and tend to eliminate the spurious effects of instability or drift in the brightness of the light source, and variations in the detector output or attenuation in the fibers, connectors or fiber/disk interface caused by temperature or aging.
  • Each of the following techniques develops a reference signal which is combined (e.g., ratioed) with the detected signal to cancel out variations other than those induced by changes in the gap width.
  • the techniques fall into four general categories.
  • the three fiber scheme is shown in Fig. 8. If the incoming light ray is wide enough or if it is allowed to diverge enough after leaving the incoming fiber 18, the area on the reflective surface on which it is incident may be larger than the boss 12b on the diaphragm 12a.- Thus, part of the reflected light ray will not be susceptible to FTR or ATR because, except for the boss area, the diaphragm 12a is too far away from the disk 22. Consequently, if a reference output fiber 21 (i.e., a third fiber overall) or an alternate light pickup is situated such that it collects only the internally reflected light which is not affected by the diaphragm, the fluctuation in intensity of the source can be detected by monitoring the reference fiber output. For example, ratio circuitry can be used to produce a ratio- of the output and reference fibers 20 and 21 so that variations in output amplitude or attenuation not ' caused by gap width are cancelled cut.
  • the second technique shown in Fig. 9 uses a light coupling scheme. Almost the same effect of the three fiber scheme can be achieved by coupling some of the light out of the input fiber before it enters the glass disk and subsequently monitoring it for fluctuations in source intensity. Although the coupling scheme is simpler, in this case the reference light coupled out will not take into account effects of variations in attenuation of the interface between the fiber and glass disk due to temperature and aging. In any event, the output of the third fiber, the reference fiber 21' could be used in the same manner . as the third fiber 21 in Fig. 8 in similar compensation circuitry to normalize the magnitude of light conveyed by the output fiber 20.
  • FIG. 10 A four fiber scheme is shown in Fig. 10.
  • two input fibers 18 and 19 or other light transmitting mechanisms
  • two output fibers 20 and 21 or other light collection mechanisms
  • Light from a single source is allowed to enter the two input fibers 18 and 19 via a divider (not shown).
  • These fibers are then directed in such a manner that the point of internal reflection for fiber 19, the reference input fiber, is far enough away from the boss 12b so that the amount of internal reflection and light picked up by the reference fiber 21 will not be affected by gap width.
  • the other pair of fibers 18 and 20 operate in the same manner as the basic transducer of Fig. 1.
  • Fig. 10 would again be used in ratio circuitry or another compensation scheme to cancel out the effects of source and attenuation variations not due to gap width.
  • the techniques of Fig. 8 and Fig. 10 are similar in that variations in the intensity of light collected from a reflection point distant from the boss take into account variations not only in light intensity, but also in attenuation through the media while remaining unaffected by gap width.
  • FIGs. 11 and 12 A fourth scheme based on multiple colors of light is illustrated in Figs. 11 and 12.
  • the transfer curves of light transmitted versus gap distance are scaled with the wave length of the light. This scaling feature applies to both FTR and ATR. If the ratio of the amount of light received at two different wave lengths is taken, the value will be a function of the gap distance. Dispersion effects will not be removed, so that if the fibers or other optical parts have substantially different characteristics at different wave lengths, the overall transfer curves of the ratio versus gap distance would be affected.
  • the ratio of the detected light at those wave lengths will be only a function of the gap distance and will not be affected by changes in attenuation so long as the source of attenuation affects both wave lengths equally.
  • Fig. 11 shows a technique in which a plurality of light emitting diodes (LED) 24' emitting light at distinct wave lengths replaces the single light source 24 of Fig. 1.
  • the LED's 24' are arranged to illuminate the input end of fiber 18.
  • the LED's can be pulsed sequentially so that extra logic in detector 28" can differentiate between the wave lengths.
  • One disadvantage of the alternative scheme of Fig. 11 is that the LED's have to be stabilized to avoid variations in their output or their individual brightness must be measured and used to compensate the response of the detector 28'.
  • a variation on the multicolor technique which eliminates the multiplicity of light sources is shown in Fig. 12.
  • a broad band white light source 24' ' such as an incandescent bulb, illuminates the input fiber 18.
  • the output of fiber 20 is fed via a beam splitter 32 to two different optical channels.
  • the respective channels are equipped with optical filters 29 and 29' which allow only light of a different selected band of wave lengths to pass to the respective detectors 28' '.
  • the ratio of the intensities of the two selected wave lengths will change much less than the absolute change of lamp brightness. Accordingly, the transducer will be essentially immune to errors caused by minor variations in lamp brightness. However, because the effects of gap width are different at different wave lengths, the gap width variations do not cancel out.
  • the advantages of the optical pressure sensor according to the invention are manifold.
  • the optical fibers allow the electrical components for generating and detecting the light beam to be removed to a location remote from the engine so as to reduce the electromagnetic and thermal effects of the engine on the circuitry.
  • the optical portion of the system is substantially unaffected by electromagnetic interference. Extremely small diaphgram deflections induced- by high pressures result in relatively large signal .changes.
  • the diaphragm can be made extremely rugged to withstand the harsh operating environment of the automotive engine.
  • the transducer is simpler in design than prior art transducers and inherently more rugged. Thus, it should be possible to manufacture the transducers at lower cost with equal or better performance and survivability.
  • the type of sensor described above can be mass produced and used in all automotive engines. Measurement of cylinder pressure would allow optimized automatic spark timing over a wide range of speed and . load for best location of peak pressure. Increased knock limit and higher compression ratios would be possible with lower octane requirements and better efficiency. Not only would such a sensor lead to better fuel economy and reduced emissions, but also combustion monitoring would permit a motor vehicle's own microprocessor to anticipate engine difficulties and implement solutions much more effectively than is now possible. It is conservatively estimated that with current engine optimization techniques based on determination of instantaneous cylinder pressure, a five percent fuel savings can be realized in a gasoline engine. This estimate, although conservative, represents very significant savings which would lead to rapid payback of development costs.
  • the optical pressure sensor has applications to other areas of technology. For example, measurement of oil well pressures would take advantage of the exceptional stability, ruggedness, and natural absolute offset of the optical pressure transducer.
  • pressurized fluid can be introduced between the diaphragm and disc for differential readings or to adjust the zero setting.
  • the thickness of the glass disk 22 has been found to have a significant effect on performance. If the disk is too thick, divergence of the beam from the end of the input fiber 18 can cause interference with the reflected beam picked up by the output fiber 20. A very thin disk on the order of one millimeter reduces the effects of divergence.
  • the cylindrical boss on the diaphragm is not essential, however, it reduces and defines the specific area that needs to be polished to a smooth parallel surface.
  • the optical fibers can be multimode or single mode. In fact, the uses of the invention are not limited to fibers. Other means for conveying and projecting a beam of light into the transparent medium can be used. Other means of collecting the reflected rays can be used as well.
  • Ceramic materials may have longer life and higher temperature stability, it should be possible to achieve satisfactory results with metal parts which can be easily machined, assuming the coefficients of thermal expansion at the glass/metal interface are compatible.
  • a ceramic coating may be desirable in any case for the surface of the diaphragm exposed to combustion.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Les phénomènes optiques connus sous le nom de réflexion interne totale diminuée et atténuée sont utilisés pour mesurer une pression. Un rayon de lumière est envoyé sur une plaque de verre fin (22) par l'intermédiaire d'une fibre optique (18). Le rayon de lumière réfléchi vers l'intérieur est véhiculé vers une cellule photographique (28) par l'intermédiaire d'une deuxième fibre optique (20). Un diaphragme (12), qui peut être solidaire avec une chambre de pression, est monté adjacent à la plaque (22) et déflecté sous pression. Au fur et à mesure que le diaphragme (12) s'approche de la plaque de verre (22), la quantité de lumière réfléchie diminue. Dans le mode de réalisation préféré, un renflement (12b) du diaphragme (12) est recouvert uniformément d'un métal doux à indice de réflexion élevé tel que de l'or, afin de provoquer l'atténuation de la totalité des réflexions. L'or est applatit en appliquant une surpression au côté exposé du diaphragme (12) et en comprimant le renflement (12b) et la plaque de verre (22) l'un contre l'autre. Le changement qui intervient dans la quantité de lumière réfléchie est traduit en un signal de pression électrique analogique. Le transducteur optique présente une bonne résistance à l'environement hostile des moteurs à combustion interne grâce à son insensibilité aux interférences électromagnétiques, aux vibrations et aux transitoires thermiques.
EP19860903974 1985-06-04 1986-06-04 Capteur optique de pression Withdrawn EP0224575A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US74099685A 1985-06-04 1985-06-04
US740996 1985-06-04

Publications (1)

Publication Number Publication Date
EP0224575A1 true EP0224575A1 (fr) 1987-06-10

Family

ID=24978932

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860903974 Withdrawn EP0224575A1 (fr) 1985-06-04 1986-06-04 Capteur optique de pression

Country Status (2)

Country Link
EP (1) EP0224575A1 (fr)
WO (1) WO1986007445A1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4942767A (en) * 1986-11-19 1990-07-24 Massachusetts Institute Of Technology Pressure transducer apparatus
US5052228A (en) * 1986-11-19 1991-10-01 Massachusetts Institute Of Technology Shear stress measuring device
DE4018998A1 (de) * 1990-06-13 1992-01-02 Dynisco Geraete Gmbh Faseroptischer drucksensor
GB9206948D0 (en) * 1992-03-31 1992-05-13 Kodak Ltd Optical fibre sensors
DE4304139A1 (de) * 1993-02-11 1994-08-18 Siemens Ag Meßanordnung zum Kalibrieren von Ultraschallstoßwellen-Sensoren
US6976395B2 (en) * 2001-08-16 2005-12-20 Adz Nagano Gmbh Optical device for measuring pressure or force
US7409863B2 (en) * 2004-10-05 2008-08-12 Sensata Technologies Maryland, Inc. Pressure sensor
EP2259039A1 (fr) 2009-06-05 2010-12-08 Simea Optic AB Système optique à fibres et son utilisation
CN102359838B (zh) * 2011-08-10 2014-04-09 陈拥军 一种激光式压力传感器
NL2010042C2 (en) * 2012-12-21 2014-06-24 Lely Patent Nv A pressure sensor.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2050486A (en) * 1934-08-01 1936-08-11 Paper Patents Co Apparatus for testing the smoothness of paper
US4165155A (en) * 1978-03-27 1979-08-21 International Business Machines Corporation Amplitude modulation of light beam
DE2937484A1 (de) * 1979-09-17 1981-05-14 Siemens AG, 1000 Berlin und 8000 München Optische vorrichtung zum messen von druckdifferenzen mittels lichtintensitaetsaenderung
US4509370A (en) * 1982-09-30 1985-04-09 Regents Of The University Of California Pressure-sensitive optrode

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8607445A1 *

Also Published As

Publication number Publication date
WO1986007445A1 (fr) 1986-12-18

Similar Documents

Publication Publication Date Title
US7340118B2 (en) Fuel injectors with integral fiber optic pressure sensors and associated compensation and status monitoring devices
EP0640819B1 (fr) Capteur de pression pour hautes températures à trois fibres optiques à ouvertures numériques différentes
US6320184B1 (en) Optoelectric measuring device for monitoring combustion processes
EP1015855B1 (fr) Injecteurs de carburant a capteurs de pression a fibres optiques solidaires et dispositifs associes de controle d'etat et de compensation
US4703175A (en) Fiber-optic sensor with two different wavelengths of light traveling together through the sensor head
US5390546A (en) Fiber optic diaphragm sensors for engine knock and misfire detection
EP0337173B1 (fr) Dispositif pour déterminer le contenu en alcool
US4083254A (en) Accelerometer
JPH05196528A (ja) 光ファイバ圧力センサ装置
EP0224575A1 (fr) Capteur optique de pression
EP0604582A1 (fr) Photometre a double longueur d'onde et sonde detectrice a fibre optique
FR2922304A1 (fr) Dispositif de spectrometrie pour l'analyse d'un fluide
EP0639266A1 (fr) Procede de fabrication d'un appareil de mesure.
CN106197492A (zh) 基于光纤复合法珀腔结构的法珀腔长与折射率计算方法
US4624570A (en) Fiber optic displacement sensor
JPS59105517A (ja) 物理的量を測定するためのフアイバ−オプテイクセンサ−
JP5629317B2 (ja) 光学式の隔膜圧力測定セルを備えた圧力測定セル構造
EP0057667B1 (fr) Dispositif pour déterminer l'indice de réfraction d'un fluide ramené à une température de réference
JPH07260617A (ja) 圧力センサ及びそれを使用する圧力測定システム
CN1079821A (zh) 基于法布里-珀罗其振腔的光学压力传感器
CN119573785A (zh) 一种基于球透镜的光纤温压传感器及其制备方法
He et al. Low-cost spark plug-integrated fiber optic sensor for combustion pressure monitoring
GB2385664A (en) Optical strain gauge sensor integrated within a cylinder head gasket
US4600836A (en) Diaphragm deflection sensor for fused silica diaphragm module
CN107607175A (zh) 一种点式光纤液位传感器

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LI LU NL SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19870305

RIN1 Information on inventor provided before grant (corrected)

Inventor name: EKCHIAN, JACK, A.

Inventor name: HOFFMAN, ROBERT, W.

Inventor name: EKCHIAN, LEON