WO1994002817A1 - Capteur de pression - Google Patents

Capteur de pression Download PDF

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Publication number
WO1994002817A1
WO1994002817A1 PCT/AU1993/000359 AU9300359W WO9402817A1 WO 1994002817 A1 WO1994002817 A1 WO 1994002817A1 AU 9300359 W AU9300359 W AU 9300359W WO 9402817 A1 WO9402817 A1 WO 9402817A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
light
medium
pressure sensor
rod
Prior art date
Application number
PCT/AU1993/000359
Other languages
English (en)
Inventor
William Richard Mitchell
Steven James Mitchell
Original Assignee
Invent Engineering Pty. Limited
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 Invent Engineering Pty. Limited filed Critical Invent Engineering Pty. Limited
Priority to AU45491/93A priority Critical patent/AU4549193A/en
Priority to EP93915538A priority patent/EP0651878A4/fr
Publication of WO1994002817A1 publication Critical patent/WO1994002817A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/40—Sparking plugs structurally combined with other devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/08—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid operated electrically
    • G01L23/16—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid operated electrically by photoelectric means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines

Definitions

  • This invention relates to a pressure sensor.
  • a pressure sensor for use for measurement of pressure in combustion chambers of engines.
  • Electronic engine management is increasingly used in engines of modern vehicles to maximise power output and minimise fuel consumption and the output of emissions.
  • the engine management system takes information including engine speed, position, temperature, inlet air pressure/temperature or inlet air mass from sensors connected to the engine. This information is used to calculate a "best guess" at the operating conditions within the combustion chambers (cylinders) of the engine which is a guess which is averaged over many cycles of the engine and over the different cylinders of the engine.
  • Engine load is typically determined from measurements of the mass of air drawn into the inlet manifold of the engine.
  • the ignition spark timing and fuel delivery are determined from algorithms that process external data such as engine speed, engine position and engine load. These methods result in some error in controlling the engine spark and fuel delivery. The error is worst during transients in the engine load.
  • the present invention seeks to provide better real time information relating to the operating conditions within the combustion chamber and information which can be specific to particular cylinders of the engine since in an engine all the cylinders do not behave identically.
  • the present invention broadly relates to a pressure sensor for insertion into a combustion chamber which is capable of measuring high gas pressures at high temperatures to produce a signal which is directly related to the pressure in a combustion chamber of that engine.
  • Such a signal measuring the rise of pressure within the cylinder from the start of an intake stroke through the entire power stroke of the engine provides a powerful tool for the designer of engine management systems to allow the engine management system to know the operating conditions within each cylinder of the engine in real time: such a sensor providing in-cylinder information from each cylinder of the engine can replace less accurate mass intake air flow measurement techniques. This allows more accurate calculation of critical engine management parameters such as fuel/air ratio and ignition spark timing. Improvements would be most evident during sudden engine transients when the advantage of real time data allows the engine management system to track the requirements of the engine with only a one cylinder cycle delay. In cylinder pressure data can also be used to determine the onset of engine knock or detonation. This allows the engine to develop maximum power without detonation.
  • a sensor including: a photoelastic medium; means for producing polarised light and directing the same through said photoelastic medium; and detecting means for measuring the alteration in polarisation of the light passing through said photoelastic medium, the arrangement being such that in use the pressure sensor can be disposed so that the photoelastic medium is subject to the pressure in the combustion chamber, changes in pressure on the photoelastic medium causing changes in the light transmission properties of the medium and hence the light detected by the detecting means produces a signal indicative of the pressure in the combustion chamber.
  • the sensor is based on the photoelastic effect in which an isotropic material can become anisotropic when subjected to an applied stress or induced strain through an elastooptic interaction known as stress birefringence.
  • the sensor utilises the change in polarisation of light as the polarised light passes through the photoelastic material or medium exposed to the pressure to be measured.
  • the light is initially polarised before entering the medium.
  • the polarisation may be set such that components of the polarisation are both perpendicular and parallel to the direction of the applied stress on the medium.
  • the birefringence induced by the applied pressure causes the components parallel to the direction of the applied stress in the material to see a different refractive index to the components perpendicular to the direction of applied stress. This results in the two components travelling at different speeds. This induces a net rotation in the plane of polarisation of the light which rotation is proportional to the distance travelled through the stress medium.
  • the light is then passed through an analyser consisting of a second polariser.
  • the intensity of the light passing through the analyser is dependent on the plane of polarisation of the light exiting the stressed medium, hence the intensity of light out of the analyser is dependent on the pressure applied to the medium.
  • the medium is a block of glass.
  • Most glasses are suitable for use as the medium including fused silica, however, one preferred material is quartz.
  • the quartz is in the form of a rod defining a longitudinal axis, disposed inside a generally tubular metal housing, the rod being fixed in a first end of the housing at which end the means for producing polarised light and the detecting means are located, the second end of the housing being open to allow pressure to act along the longitudinal axis of the rod and compress the rod in that longitudinal direction.
  • the pressure sensor is screwed or otherwise fitted into a combustion chamber with the second end located inside the chamber.
  • the means for producing polarised light comprise a light source such as a light emitting diode (led) and a polarising film.
  • the pressure of combustion and compression inside the chamber may be directly exposed to the second end of the quartz rod or alternatively may be transmitted to the rod by a mechanical linkage such as a push rod, lever system or by a fluid link.
  • Suitable light sources can include light incandescent globes or laser diodes as well as leds.
  • the photoelastic effect is dependent upon the wavelength of light passing through the medium so single wavelength sources are preferred.
  • the light source may be mounted inside the metal housing of the sensor or, alternatively it may be fed to the sensor by an optical fibre.
  • the polarising and analysing elements may be provided by separate sheets of polarising material placed adjacent opposite sides of the medium; alternatively they may be fabricated onto the sides of the medium.
  • the sensor may use only one polariser that doubles as an analyser by reflecting the light by fresnel reflection and/or coatings applied to the opposite side of the material. The light would then pass through the block twice and could leave the sensor along the same optical fibre on which it entered.
  • the sensor uses a separate polariser and analyser rotated with respect to each other by 90 then the sensor would give zero output intensity for zero applied pressure. If the sensor uses only one polariser which doubles as an analyser then the sensor would give maximum output for zero applied pressure.
  • the light intensity out of the analyser could either be converted into an electrical signal by, for example, standard photo detectors such as pin diodes or phototransistors or alternatively it could be further processed as an optical signal.
  • the detector may be mounted inside the sensor housing; alternatively it may be remotely mounted and fed the light from the analyser by an optical fibre.
  • the pressure sensor may be incorporated into an ignition spark plug.
  • the material may be a cylinder of quartz having a central bore in which the copper core of the spark plug passes and may be surrounded by a metal housing which also forms part of the spark plug.
  • Optical fibres or the like may be incorporated into the housing to provide a path for light passing through the quartz tube. Because of the location of the copper core running through the centre of the quartz tube the optical path is offset from the centre of the tube.
  • the optical fibre may be contained in the high tension leads that connect the ignition cords or distributor to the ignition spark plugs.
  • the ignition driver, ignition coil, spark plug and pressure sensor are integrated into a single assembly so that the spark may be automatically triggered at some predetermined in cylinder pressure.
  • Figure 1 shows a first pressure sensor in which a polarised light source and detector are located in a single sensor housing
  • Figure 2 is a schematic representation of components for a pressure sensor in which a light source and a detector are remotely mounted
  • Figure 3 shows a pressure sensor incorporated into a spark plug; and Figure 4 shows a similar pressure sensor to that of figure 3.
  • Figure 1 shows a pressure sensor 1 for insertion into the combustion chamber of an engine.
  • the sensor includes a metal housing 2 having a generally annular cross-section inside which there is a 12.5mm diameter quartz rod 4 defining a central longitudinal axis 5.
  • first end 3 of the sensor on one side of the quartz rod 4 there is an led 6 to provide a light source and a first polariser 8 comprising a film of polarising material; on the opposite side of the rod there is a second polariser 10 which acts as an analyser and a photovoltaic cell or detector 12.
  • the other (second) end 14 of the housing is covered by a copper crush washer 16, the diameter of the central hole 18 of the copper crush washer being smaller than the diameter of the quartz rod which helps retain the quartz rod in the housing but which allows pressure to impinge directly on free end 19 of the quartz rod though the central hole 18.
  • Blow holes 20 are provided to relieve any pressure built up between the quartz rod and the inside of the housing.
  • the housing includes means (not shown) for screwing or otherwise fitting the pressure sensor into a combustion chamber as well as means for compressing or prestressing the quartz rod by means of an adjustment bolt 21 which is provided for that purpose.
  • the pressure sensor is fitted in a combustion chamber with the second end of the housing including the blow holes 20 inside the chamber and the first end 3 located outside the chamber.
  • the light source 8 and polariser 6 combine to produce polarised light such that the components of the polarisation are perpendicular and parallel to the longitudinal axis of the rod.
  • pressure acts on the free end 19 of the rod and this compresses the quartz rod along the longitudinal axis and causes the components of polarisation parallel to the direction of the axis to see a different refractive index to the components perpendicular to the axis which induces a net rotation in the plane of polarisation of the light.
  • the intensity of the light passing through the analyser is dependent on the plane of polarisation of the light exiting the quartz rod hence intensity of light out of the analyser 10 is dependent on the pressure applied to the quartz rod, in the manner discussed in the introduction to this application.
  • the light may then converted to an electrical signal by the photovoltaic cell 12 whose signal depends on the light intensity and the resultant electrical signal can then be analysed by an engine management system.
  • Figure 2 illustrates one possible design of pressure sensor where the source and detector are remotely mounted from the sensor.
  • a light source 24 passes a light through a 50% transmission/50% reflection mirror 26 angled at 45 to the direction of travel of the light beam, to a lens 28 which focuses the light and then passes it into a multimode optical fibre 30 and the light is transmitted via the fibre to a GRIN (graded refractive index) lens 32 where it passes through a polariser 34 through a quartz sensor element 36.
  • GRIN graded refractive index
  • the mirror and lens 28 which act as an optical splitter would be replaced by a twisted fibre optic equivalent to make the system less vibration sensitive.
  • Figure 3 shows a combined pressure sensor and spark plug 50 in which a 3mm diameter core 52 of the spark plug 50 is encased in a quartz tube 54 having a 9mm outside diameter and a 3mm inside diameter which is in turn mounted in a metal housing 55.
  • An optical path 56 is provided through the housing to allow light to pass through the quartz sensor element 54 via polarisers (58, 60) placed on opposite sides of the quartz tube. The optical path is offset from the diameter of the quartz tube due to the location of the copper core passing through the centre of the tube.
  • a metal C ring 59 located just above the optical path, as oriented in Figure 3, fixes the quartz tube in the housing to enable the tube to be compressed by pressure acting on the free end 61 of the rod.
  • Figure 4 shows a combined pressure sensor and spark plug 60. This is similar to that shown in figure 3 except that the light to and from the sensor is carried in multimode optical fibres incorporated into the high tension leads of the ignition system.
  • the high tension spark is carried though a conducting core 61 of a high tension cable 62.
  • Light passes from a remotely mounted source (not shown) through an optical fibre 63 to a grin lens 64.
  • the grin lens 64 expands the light beam from the optical fibre.
  • the light is then turned through 90 degrees by a prism 65 to pass through a polariser 70 and then through a quartz rod 67 along optical path 66 which is at 90 degrees to the axis of applied pressure on the quartz rod. After passing through the quartz rod, the light passes through polariser
  • This embodiment of the sensor also shows a ceramic end 73 attached to the quartz rod.
  • the ceramic acts as a push rod which applies pressure on the quartz rod while protecting the end of the quartz rod from damage.
  • the ceramic could be bonded to the quartz rod using techniques such as fritting or gluing.
  • the ceramic and quartz can be bonded to the conducting core with a gap in the core allowing both movement and conductivity achieved by mechanical means such as insertion of a spring.
  • the quartz may also be rigidly attached to the outer metal housing with pressure being transferred at the centre of the quartz by means of a push rod to a fraction of that part of the cross-sectional area designed to accept pressure and compression at the centre within the material to provide the required bi-refringence effect.
  • a push rod to a fraction of that part of the cross-sectional area designed to accept pressure and compression at the centre within the material to provide the required bi-refringence effect.
  • the devices described above are particularly suited for testing and research and development purposes.
  • the data provided by the devices can give a means to calculate engine power.
  • the invention has been described with reference to the use of the pressure sensor in combustion chambers/cylinders of engines. However the sensor can be adapted for use in other control or measurement applications where a pressure sensor of rugged design is required.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Un capteur de pression (1) destiné à mesurer la pression dans une chambre de combustion ou similiaire comprend un milieu photoélastique (6) tel qu'un quartz pour diriger une lumière polarisée dans ledit milieu photoélastique (6) et un moyen de détection (12) destiné à détecter le changement de polarisation de la lumière après qu'elle soit passée dans ledit milieu photo élastique (6). En service, le capteur de pression est disposé de manière que le milieu photoélastique (6) soit soumis à la pression dans la chambre de combustion. Les changements de pression agissant sur le milieu provoquent des changements dans les propriétés de transmission de la lumière et donc influent sur la lumière détectée par le moyen de détection (12), produisant ainsi un signal indicateur de la pression dans ladite chambre de combustion à laquelle le milieu est soumis.
PCT/AU1993/000359 1992-07-20 1993-07-19 Capteur de pression WO1994002817A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU45491/93A AU4549193A (en) 1992-07-20 1993-07-19 Pressure sensor
EP93915538A EP0651878A4 (fr) 1992-07-20 1993-07-19 Capteur de pression.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPL360392 1992-07-20
AUPL3603 1992-07-20

Publications (1)

Publication Number Publication Date
WO1994002817A1 true WO1994002817A1 (fr) 1994-02-03

Family

ID=3776301

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1993/000359 WO1994002817A1 (fr) 1992-07-20 1993-07-19 Capteur de pression

Country Status (2)

Country Link
EP (1) EP0651878A4 (fr)
WO (1) WO1994002817A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT503067B1 (de) * 2007-03-08 2008-08-15 Avl List Gmbh Zündkerze

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415436A (en) * 1944-07-31 1947-02-11 Harry B Maris Photoelastic blast pressure gauge
US4321831A (en) * 1980-09-26 1982-03-30 United Technologies Corporation Digitally compatible optical pressure measurement
GB2084316A (en) * 1980-09-26 1982-04-07 United Technologies Corp Optical pressure measuring apparatus
US4757195A (en) * 1985-06-27 1988-07-12 Sharp Kabushiki Kaisha Optical pressure sensor with pedestal mounted photoelastic element
GB2223094A (en) * 1988-09-24 1990-03-28 Dobson Park Ind Pressure transducer
EP0441157A2 (fr) * 1990-01-22 1991-08-14 Nippondenso Co., Ltd. Bougie d'allumage avec capteur de pression
WO1991012511A1 (fr) * 1990-02-14 1991-08-22 Meyer Ifergan Installation de controle de la compression d'un moteur a combustion interne

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1008646A (fr) * 1948-05-05 1952-05-20 Onera (Off Nat Aerospatiale) Capteur de pression pour manographes photo-élastiques
FR1011786A (fr) * 1949-03-21 1952-06-26 Onera (Off Nat Aerospatiale) Perfectionnements aux manographes photo-élastiques
GB1068014A (en) * 1965-01-22 1967-05-10 Ivor Hawkes Improvements in or relating to pressure gauges
US4495819A (en) * 1982-12-23 1985-01-29 Gould Inc. Optical pressure sensor
JPS61118633A (ja) * 1984-11-14 1986-06-05 Mitsubishi Electric Corp 光フアイバセンサ

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415436A (en) * 1944-07-31 1947-02-11 Harry B Maris Photoelastic blast pressure gauge
US4321831A (en) * 1980-09-26 1982-03-30 United Technologies Corporation Digitally compatible optical pressure measurement
GB2084316A (en) * 1980-09-26 1982-04-07 United Technologies Corp Optical pressure measuring apparatus
US4757195A (en) * 1985-06-27 1988-07-12 Sharp Kabushiki Kaisha Optical pressure sensor with pedestal mounted photoelastic element
GB2223094A (en) * 1988-09-24 1990-03-28 Dobson Park Ind Pressure transducer
EP0441157A2 (fr) * 1990-01-22 1991-08-14 Nippondenso Co., Ltd. Bougie d'allumage avec capteur de pression
WO1991012511A1 (fr) * 1990-02-14 1991-08-22 Meyer Ifergan Installation de controle de la compression d'un moteur a combustion interne

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, P 202, page 151; & JP,A,58 048 828 (MITSUBISHI DENKI K.K.) 22 March 1983 (22.03.83). *
See also references of EP0651878A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT503067B1 (de) * 2007-03-08 2008-08-15 Avl List Gmbh Zündkerze

Also Published As

Publication number Publication date
EP0651878A1 (fr) 1995-05-10
EP0651878A4 (fr) 1996-01-24

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