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WO2016024041A1 - Capteur de pression - Google Patents

Capteur de pression Download PDF

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Publication number
WO2016024041A1
WO2016024041A1 PCT/FI2015/050508 FI2015050508W WO2016024041A1 WO 2016024041 A1 WO2016024041 A1 WO 2016024041A1 FI 2015050508 W FI2015050508 W FI 2015050508W WO 2016024041 A1 WO2016024041 A1 WO 2016024041A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure sensor
circuit board
cavity
ultrasound transmitter
sensor
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.)
Ceased
Application number
PCT/FI2015/050508
Other languages
English (en)
Inventor
Teuvo SILLANPÄÄ
Hannu Sipola
Heikki SEPPÄ
Niklas Doktar
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.)
Wartsila Finland Oy
VTT Technical Research Centre of Finland Ltd
Original Assignee
Wartsila Finland Oy
VTT Technical Research Centre of Finland Ltd
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 Wartsila Finland Oy, VTT Technical Research Centre of Finland Ltd filed Critical Wartsila Finland Oy
Publication of WO2016024041A1 publication Critical patent/WO2016024041A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • G01L23/26—Details or accessories
    • G01L23/28—Cooling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/08—Safety, indicating, or supervising devices
    • F02B77/085—Safety, indicating, or supervising devices with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
    • G01L11/04—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by acoustic means
    • G01L11/06—Ultrasonic means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/0681—Protection against excessive heat
    • 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
    • G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
    • G01L9/0008—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations
    • G01L9/0016—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations of a diaphragm
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/04—Testing internal-combustion engines
    • G01M15/08—Testing internal-combustion engines by monitoring pressure in cylinders

Definitions

  • the present invention relates to a pressure sensor.
  • the invention relates to a pressure-measuring plug for an engine, such as a marine diesel engine, with a plug body for insertion into a cylinder head of the engine.
  • the invention further relates to a computer readable medium having stored thereon a set of computer implementable instructions .
  • the pressure sensors may be, for example, used for pressure measurement in a combustion chamber of a cylinder of an engine. Such engines may comprise, for example, low-speed or medium-speed diesel engines for ship propulsion. Cylinder pressure sensors are key components in closed loop engine control.
  • the existing cylinder pressure sensors are typically of the piezoresistive or piezoelectrical type. Piezoresistive sensors include a strain gauge which is attached to the bending membrane. The bending membrane deforms the gauge and the electrical resistivity of the sensor gauge changes. The change of the electrical resistivity can be measured.
  • Piezoelectrical sensors include a piezoelectrical ceramic which is compressed with pretension in between a moving membrane and a rigid support. Applying pressure to the membrane causes an electrical charge which can be measured.
  • Document US 4,500,864 discloses a pressure sensor which converts fluid pressures into electrical signals by the deformation of a diaphragm.
  • the pressure sensor is comprised of a strain gauge which includes a resistance body of amorphous metal material which may be formed directly on the diaphragm by means of a physical vapor deposition process.
  • An electric circuit board is secured to the main body and is connected to the strain gauge by means of a lead wire and is connected to an external circuit by means of lead wires.
  • Document US 5,714,680 teaches a method and apparatus for measuring pressure in a combustion chamber of an internal combustion engine 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.
  • FFPI fiber Fabry- Perot Interferometer
  • 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.
  • the senor comprises an ultrasound transmitter and a cavity arranged in connection with it.
  • the sensor comprises a passive sensor element located at the opposite end of the cavity to the ultrasound transmitter, the distance of which from the ultrasound transmitter is selected in such a way that the resonance condition is met at the ultrasound frequency used.
  • the ultrasound transmitter comprises a diaphragm oscillator, which is connected to the surrounding medium, and the sensor includes means for measuring the interaction between the ultrasound transmitter and the cavity.
  • the sensor is neither notably heat-resistant nor pressure-resistant.
  • Ultrasonic sensors for detecting an ultrasonic wave are described in US 2008/0073998 Al .
  • the ultrasonic wave is output from an ultrasonic generator and reflected by an object to be detected.
  • the ultrasonic sensor includes: an acoustic matching layer having a first surface and a second surface, the first surface which receives the ultrasonic wave, and the second surface which is opposite to the first surface; and an ultrasonic detection element including a vibration member.
  • the vibration member is coupled with the second surface of the acoustic matching layer.
  • the acoustic matching layer is repeatedly deformable in accordance with a standing wave, which is generated in the acoustic matching layer by the received ultrasonic wave.
  • the vibration member resonates with the repeat deformation of the acoustic matching layer.
  • An object of certain embodiments of the present invention is to provide a pressure sensor.
  • an object of certain embodiments of the present invention is to provide a cylinder pressure sensor with improved reliability and lifetime, which sensor comprises a plug body for insertion into a cylinder head of an engine.
  • An object of further embodiments of the invention is to provide a pressure sensor for high temperature applications with high pressure changes, wherein mechanical and/or thermal stresses resulting from a hot measurement environment are reduced in order to avoid breaking of the measurement element and/or the electrical contacts.
  • an object of certain embodiments of the present invention is to provide a computer readable medium.
  • a pressure sensor comprising an ultrasound transmitter, and a cavity arranged in connection with this, which is in resonance mode at an ultrasound frequency used, and wherein the sensor comprises a bending membrane, located at the opposite end of the cavity to the ultrasound transmitter, and the ultrasound transmitter comprises a diaphragm oscillator configured to operate either at a resonance frequency of a diaphragm or below, which oscillator is connected to the surrounding medium, and the sensor contains means for measuring the interaction between the ultrasound transmitter and the cavity, and a thermal insulation circuit board is arranged between the ultrasound transmitter and a readout circuit board, wherein the thermal insulation circuit board is configured to cause a negative temperature flow gradient in the direction from the ultrasound transmitter to the readout circuit board.
  • the distance of the diaphragm from the bending membrane is selected in resonance operation such that a cavity resonance frequency equals a diaphragm frequency.
  • the sensor is based on an ultrasound transmitter, which comprises an oscillation source in the form of a diaphragm.
  • An ultrasound cavity is arranged in connection with the ultrasound transmitter and filled with the surrounding medium, i.e. a gas or gas mixture.
  • the dimensions of the cavity are arranged to resonate at the operating frequency of the ultrasound transmitter.
  • one of the main dimensions of the cavity i.e. the cavity length, is dimensioned to be a quarter, a half, or a multiple of these, of the wavelength of the ultrasound.
  • the measurement can be realized either in one port configuration or in two port configuration.
  • the ultrasound transmitter works as a transmitter and as a receiver.
  • the ultrasound transmitter contains means for sending an ultrasonic wave and measuring the interaction between the transmitter and the cavity.
  • two port configuration at least two components are needed. One of them will work as a transmitter and a second one will work as a receiver. The operation principle is the same as in one port solution.
  • the impedance will be observed to be strongly dependent on the deviation of the cavity relative to the aforementioned length. If operation takes place in the series resonance of the ultrasound, small changes in the impedance of the transmitter will be directly proportional to the cavity length and the width of resonance will be proportional to the damping in the cavity.
  • the geometry of the sensor is arranged in such a way that the variable being measured affects the length of the cavity.
  • the pressure sensor comprises a plug body.
  • the plug body includes a surrounding wall and the bending membrane.
  • the ultrasound transmitter, the thermal insulation circuit board and the readout circuit board are arranged in the plug body.
  • the pressure sensor is configured to be inserted into a cylinder head of an engine.
  • One side of the bending membrane forms a facing surface which is configured to directly face a combustion chamber of the engine.
  • an air insulation gap is arranged between the surrounding wall of the plug body and at least one of a first sleeve, the thermal insulation circuit board, a second sleeve, and the readout circuit board .
  • the senor is configured to control a resonance frequency of the transmitter by means of bias adjustment such that the resonance frequency of the transmitter essentially equals a resonance frequency of the cavity.
  • the sensor is configured to measure the impedance of the transmitter at fixed excitation frequency f e which equals the resonance frequency of the coupled resonator fo when the bending membrane is in stationary rest position.
  • the sensor is configured to control an excitation frequency in a way that an acoustic cavity length is kept at a value which equals the acoustic cavity length when the bending membrane is in stationary rest position.
  • a thermal distribution disc is arranged in the cavity between the ultrasound transmitter and the bending membrane.
  • the thermal distribution disc comprises at least one disc pin which is arranged on one side of the thermal distribution disc and faces the bending membrane. The at least one disc pin and a peripheral edge of the thermal distribution disc are directly in contact with the bending membrane.
  • a first cavity length between the ultrasound transmitter and the bending membrane is in stationary rest position of the bending membrane one quarter, one half, or a multiple of these, of the wavelength of the ultrasound frequency used.
  • a second cavity length between the ultrasound transmitter and the thermal distribution disc is in stationary rest position of the bending membrane one quarter, one half, or a multiple of these, of the wavelength of the ultrasound frequency used.
  • the senor includes a height adjuster which is arranged between the thermal insulation circuit board and the bending membrane.
  • the height adjuster is a height adjustment ring or bimetal spring and is capable of adjusting the first cavity length between the ultrasound transmitter and the bending membrane depending on the cavity temperature in such a way that the resonance condition is met.
  • the senor includes a height adjuster which is arranged between the thermal insulation circuit board and the thermal distribution disc.
  • the height adjuster is a height adjustment ring or bimetal spring and is capable of adjusting the second cavity length between the ultrasound transmitter and the thermal distribution disc depending on the cavity temperature in such a way that the resonance condition is met.
  • a computer readable medium having stored thereon a set of computer implementable instructions capable of causing a processor, in connection with the pressure sensor according to any one of claims 1 to 20, to calculate a pressure in a measurement environment and/or output pressure information depending on an effective cavity length.
  • a pressure sensor with improved reliability and lifetime. Mechanical stresses can be reduced due to the noncontact displacement measurement of the bending membrane. Thermal insulation of the measurement element, i.e. the ultrasound transmitter, is not required.
  • the thermal insulation circuit board which is arranged separately from the readout circuit board, further reduces thermal stresses to the readout circuit board during measurement in a measurement environment.
  • an air insulation gap will isolate the readout circuit board from the surrounding wall of the sensor housing.
  • a metal sleeve will conduct heat to the upper part of the surrounding wall and/or a cap of the housing.
  • the invention is especially advantageous for high temperature applications with high pressure changes. Compared to piezoresistive or piezoelectrical sensors, a significant improvement in sensitivity is further achieved.
  • the sensor can be used directly to replace piezo sensors and is less sensitive to, for example, problems arising from torsion.
  • a cylinder pressure sensor including a thermal distribution disc for further reduction of thermal stresses in the measurement area during operation of an engine.
  • Thermal stresses can be additionally reduced by means of an air insulation gap and a metal sleeve which conducts the heat to the upper part of the surrounding wall and the cap.
  • the temperature in the area where the readout circuit board and readout LNA (Low Noise Amplifier) and impedance to pressure converter unit are located can be reduced, for example to temperatures in the range between 150 [ ° C] and 100 [ ° C] or to temperatures less than 100 [ ° C] .
  • Mechanical and thermal stresses resulting from the combustion chamber of the cylinder during operation of the engine do not break the ultrasound transmitter or the electrical contacts.
  • the lifetime of the cylinder pressure sensor can be significantly improved and meets the requirements according to certain embodiments. Quick and easy insertion and removal of the plug body is further possible. [0023] Additionally, the mechanical structures of the embodiments of the invention are uncomplicated, thus reducing the price of the sensors and improving reliability and lifetime.
  • FIG. 1 illustrates a schematic cross- sectional view of a pressure sensor according to a first embodiment of the invention
  • FIG. 2 illustrates a schematic cross- sectional view of a pressure sensor according to a second embodiment of the invention
  • FIG. 3 illustrates a schematic cross- sectional view of a pressure sensor according to a third embodiment of the invention
  • Fig. 4 illustrates a schematic cross- sectional view of a pressure sensor according to a fourth embodiment of the invention
  • Fig. 5 illustrates a schematic side view of a plug body of a pressure sensor according to a fifth embodiment of the invention
  • Fig. 6 illustrates a schematic graph of a pressure curve in a combustion chamber evolving throughout an engine operating cycle.
  • Fig. 1 a schematic cross-sectional view of a pressure sensor 1 according to a first embodiment of the invention is illustrated.
  • the pressure sensor 1 comprises an ultrasound transmitter 2 which is arranged in a plug body 15 and configured to output an ultrasonic wave.
  • the ultrasound transmitter 2 comprises an oscillation source in the form of a diaphragm.
  • An acoustic cavity 3 is arranged in connection with the ultrasonic transmitter 2 and a passive bending membrane 5 is located at the opposite end of the acoustic cavity 3.
  • the cavity 3 is filled with a gas mixture such as air but may be also filled with another gas or gas mixture.
  • the bending membrane 5 is an integral part of the plug body 15 and typically made of metal, for example made of stainless steel.
  • the thickness of the passive bending membrane 5 may be, for example, in the range between 0.8 [mm] and 1.5 [mm] and the diameter of the passive bending membrane 5 may be, for example, in the range between 8.0 [mm] and 15.0 [mm] .
  • the ultrasound transmitter 2 is mounted to a thermal insulation circuit board 4, for example a ceramic thermal insulation board.
  • the cavity length li between the bending membrane 5 and the ultrasound transmitter 2 is fixed by means of a first metal sleeve 6.
  • the diaphragm of the ultrasound transmitter 2 is configured to create a resonating ultrasound in the cavity 3.
  • the ultrasound transmitter 2 creates both electrical series and parallel resonance.
  • the reflected ultrasound wave arrives at the ultrasound diaphragm in phase, which increases the movement of the diaphragm.
  • the ultrasonic resonance cavity principle relies on the fact that the impedance of the resonance cavity depends on the distance between the surface of the bending membrane 5 and the detector's surface relative to the ultrasonic wavelength ⁇ .
  • the cavity impedance is a minimum when the distance between the surfaces is one half of the ultrasonic wavelength ⁇ . Bending of the membrane 5 due to the pressure changes in an measurement environment will manifest a modulation of the effective cavity length li and cause a mismatch to the ultrasonic wavelength ⁇ . Thus, the cavity impedance is detuned. Monitoring of the changes of cavity impedance provides the required information on the displacement.
  • the readout circuit for detection of cavity impedance changes can be implemented electronically.
  • the sensor 1 is configured to control a resonance frequency f t of the ultrasound transmitter 2 by means of bias adjustment such that the resonance frequency of the transmitter f t essentially equals a resonance frequency of the cavity f c in order to achieve a resonating ultrasound.
  • the term "essentially equals" means that the resonance frequency of the transmitter f t differs from the resonance frequency of the cavity t c by less than the factor of 1/Q. In an optimal case the resonance frequency of the transmitter f t exactly equals the resonance frequency of the cavity f c .
  • a signal fo represents a resonance frequency of the cavity coupled resonator.
  • the resonance frequency of the cavity coupled resonator fo exactly equals the resonance frequency of the transmitter f t and the resonance frequency of the cavity f c .
  • Af fo/Q is at least equal or more than the bandwith needed for the pressure measurement.
  • the Q value of the resonance may be, for example, 200 and the bandwith may be, for example 10 kHz and thus the operation frequency is at least 2 MHz.
  • the electronics can then calculate the effective pressure in the measurement environment by means of the resonance frequency of the cavity coupled resonator f 0 .
  • the system 1 is further configured to control the excitation frequency of the ultrasound transmitter f e in such a way that the excitation frequency of the ultrasound transmitter f e equals the resonance frequency fo of the coupled resonator when the bending membrane is in stationary rest position.
  • the information about the effective cavity length li as well as the pressure in the measurement environment is contained in the transmitter impedance. Otherwise, the measurement may take place in such a way that the cavity impedance is measured and kept constant by means of adjustment of the operation frequency f e .
  • the senor 1 is configured to control the excitation frequency f e in a way that the acoustic length of the cavity is kept at a value which equals the acoustic cavity length when the bending membrane is in stationary rest position.
  • the information about the pressure is contained in the excitation frequency f e , thus providing a large linear cavity length measurement range.
  • the ultrasound transmitter 2 is typically attached to the thermal insulation circuit board 4 by means of an adhesive.
  • the adhesive used in the embodiment may be, for example, a high temperature glue.
  • the adhesive used is selected in such a way that the adhesive used will have sufficient adhesion to the ultrasound transmitter and the thermal insulation circuit board 4 depending on the expected temperature range of the measurement environment.
  • the thermal insulation circuit board 4 is arranged parallel to a readout circuit board 7.
  • the thermal insulation circuit board 4 is configured to cause a negative temperature flow gradient in the direction from the ultrasound transmitter 2 to the readout circuit board 7 in order to reduce thermal stresses to the readout circuit board 7 during measurement in a measurement environment.
  • the thermal insulation board 4 is further configured to send electric signals between the ultrasound transmitter 2 and the readout circuit board 7 bidirectionally .
  • the thermal insulation circuit board includes vias filled with conducting material in order to provide electrical contacts with excellent electrical properties on both sides of the thermal insulation circuit board 7, thus providing a high durability of the thermal insulation board 4. This is especially important when using the pressure sensor 1 as a cylinder pressure sensor in an engine.
  • the readout circuit board 7 is arranged via pins 12 and a protrusion of a second metal sleeve 8 separately from the thermal insulation circuit board 4 in such a way that the influence of the thermal flow from the surrounding wall 9 of the plug body 15 is minimized.
  • the pins 12 are typically made from conducting material and configured to send the electric signals between the thermal insulation circuit board 4 and the readout circuit board 7.
  • the pins may be, for example, so called pogo pins and each located on an electrical contact of the thermal insulation circuit board 4.
  • feed-throughs for electric cables are provided in the thermal insulation circuit board 4.
  • the second metal sleeve 8 conducts the heat to the upper part of the surrounding wall 9 and the cap 10.
  • the second metal sleeve 8 is thermally anchored to the surrounding wall 9 and/or the cap 10 at the end of the second metal sleeve 8 which is opposite to the thermal insulation circuit board.
  • the second metal sleeve 8 represents a heat sink.
  • the thickness of the surrounding wall 9 may be, for example, in the range between 1.5 [mm] and 3.5 [mm] and the thickness of the second metal sleeve 8 may be, for example, in the range between 1.0 [mm] and 3.0 [mm] .
  • an air insulation gap 11 is arranged between the surrounding wall 9 of the plug body 15 and the first sleeve 6, the thermal insulation circuit board 4, and the second sleeve 8.
  • the thickness of the air insulation gap 11 may be, for example, in the range between 0.5 [mm] and 2.0 [mm] .
  • the pressure sensor 1 is configured to be inserted into a cylinder head of a reciprocating piston engine such as a diesel engine.
  • the cylinder pressure sensor 1 may be, for example, inserted into cylinder heads of low-speed diesel engines or medium-speed engines.
  • Low-speed engines are primarily used to power ships and typically operate in the range from 60 [rpm] to 200 [rpm] .
  • Medium-speed engines are typically used in ship propulsion, electrical generators, and mechanical drive applications.
  • the cylinder pressure sensor 1 By means of the cylinder pressure sensor 1 according to the embodiments it is possible to realize noncontact displacement measurement of the bending membrane 5, thus reducing mechanical stresses.
  • the aforementioned surface side of the bending membrane 5 becomes extremely hot, for example 300 [ ° C], 360 [ ° C] or 400 [ ° C].
  • the readout sensor mounting base i.e. the thermal insulation circuit board 4, works as a circuit board for the ultrasonic transmitter and thermal barrier for the readout electronics which are located in a separate readout circuit board 7.
  • the temperature in the area where the readout circuit board 7 is located may be, for example, 150 [ ° C], 120 [ ° C], 100 [ ° C] or less than 100 [ ° C], thus reducing the risk of thermally damaging the electronics. Due to the noncontact displacement measurement, further thermal insulation of the ultrasound transmitter 2 is not required.
  • the temperature in the area where the ultrasound transmitter 2 is located is between the temperature of the bending membrane 5 and the temperature in the area where the readout circuit board 7 is located.
  • the temperature in the area where the ultrasound transmitter is located may be, for example, 220 [ ° C], 200 [ ° C], or 180 [ ° C].
  • the pressure sensor 1 includes a temperature sensor in order to measure the cavity temperature. The pressure sensor 1 is advantageous for high temperature applications with high pressure changes.
  • FIG. 2 a schematic cross-sectional view of a pressure sensor 1 according to a second embodiment of the invention is illustrated.
  • the pressure sensor 1 comprises an ultrasound transmitter 2 which is arranged in a plug body 15 and configured to output an ultrasonic wave.
  • An acoustic cavity 3 is arranged in connection with the ultrasonic transmitter 2 and a passive bending membrane 5 is located at the opposite end of the acoustic cavity 3.
  • oscillating ultrasound transmitters 2 may be used in parallel.
  • the ultrasound transmitter 2 is mounted to a thermal insulation circuit board 4 and the distance li between the bending membrane 5 and the thermal insulation circuit board 7, i.e. the effective cavity length, is fixed by means of a first metal sleeve 6.
  • the readout circuit board 7 is arranged on top of and perpendicular to the thermal insulation circuit board 4. Due to the orientation of the readout circuit board, specific components of the readout circuit board 7 are arranged more far away from the hot bending membrane 5 than according to the solution presented in Fig. 1. Further, on both sides of the readout circuit board 7 the gas or gas mixture volume is the same, i.e. the heat distribution is essentially the same on both sides of the readout circuit board.
  • the second metal sleeve 6 conducts the heat to the upper part of the surrounding wall of the plug body 15 and the cap 10. Additionally, an air insulation gap 11 is arranged between the surrounding wall 9 of the plug body 15 and the first sleeve 6, the thermal insulation circuit board 4, and the second sleeve 8.
  • the thermal insulation circuit board 4 is configured to cause a negative temperature flow gradient in the direction from the ultrasound transmitter 2 to the readout circuit board 7 in order to reduce thermal stresses to the readout circuit board 7 during measurement in a measurement environment.
  • FIG. 3 a schematic cross-sectional view of a pressure sensor 1 according to a third embodiment of the invention is illustrated.
  • the pressure sensor 1 comprises an ultrasound transmitter 2 which is arranged in a plug body 15 and configured to output an ultrasonic wave.
  • An acoustic cavity 3 is arranged in connection with the ultrasonic transmitter 2 and a passive bending membrane 5 is located at the opposite end of the acoustic cavity 3.
  • the ultrasound transmitter 2 is mounted to a ceramic thermal insulation circuit board 4.
  • the ceramic thermal insulation circuit board 4 is configured to cause a negative temperature flow gradient in the direction from the ultrasound transmitter 2 to the readout circuit board 7 in order to reduce thermal stresses to the readout circuit board 7 during pressure measurement in a measurement environment.
  • a thermal distribution disc 13 is further arranged in the cavity 3 between the ultrasound transmitter 2 and the bending membrane 5.
  • the thermal distribution disc 13 comprises a disc pin 14 which is arranged on one side of the thermal distribution disc 13 and faces the center of the bending membrane 5. Only the disc pin 14 and the peripheral edge of the thermal distribution disc 13 are directly in contact with the bending membrane 5. By means of the thermal distribution disc 13 and the disc pin 14 heat can be conducted away from the center of the bending membrane 5, i.e. the measurement area, to the peripheral edge of the thermal distribution disc 13. The distance between the ultrasound transmitter 2 and the upper surface of the thermal distribution disc 13, i.e.
  • Bending of the membrane 5 due to the pressure changes for example in a combustion chamber of a cylinder of a diesel engine, will manifest a modulation of the effective cavity length 1 2 and cause a mismatch to the ultrasonic wavelength ⁇ .
  • the cavity impedance is detuned. Monitoring of the changes of cavity impedance provides the required information on the displacement.
  • the readout circuit for detection of cavity impedance changes can be implemented electronically.
  • FIG. 4 a schematic cross-sectional view of a pressure sensor according to a fourth embodiment of the invention is illustrated.
  • a height adjustment ring 16 is arranged between the thermal insulation circuit board 4 and the bending membrane 5.
  • Other embodiments may include bimetal springs instead of the height adjustment ring 16.
  • the speed of sound changes depending on the temperature of the gas or gas mixture in the cavity 3.
  • the height adjustment ring 16 and the bimetal springs are capable of adjusting the cavity length li between the ultrasound transmitter 2 and the thermal distribution disc 13 depending on the cavity temperature in such a way that the resonance condition is met.
  • Springs 19 are arranged between the thermal insulation circuit board 4 and the second sleeve 8 in order to allow adjustment of the cavity length li depending on the cavity temperature. With increasing cavity temperature the height adjustment ring 16 or the bimetal springs will increase the cavity length li by moving the thermal insulation circuit board in the direction of the cap 10 and vice versa.
  • Such a pressure sensor 1 is advantageous in applications with high temperature changes.
  • Fig. 5 a schematic side view of a plug body of a pressure sensor according to a fifth embodiment of the invention is illustrated.
  • the plug body 15 of the sensor 1 is configured to be inserted into a cylinder head of a marine diesel engine.
  • the plug body 15 includes a thread 17 on the outside surface of the surrounding wall 9 for uncomplicated and quick insertion and removal of the sensor 1.
  • the ultrasound transmitter 2, the thermal insulation circuit board 4 and the readout circuit board 7, which are not shown in Fig. 5, are arranged in the plug body 15.
  • the bending membrane 5 is in direct contact with the combustion chamber of the cylinder.
  • the sensor 1 is connected to an electronic system such as a computing device 18 which comprises a computer readable medium.
  • a set of computer implementable instructions is stored thereon. The instructions are capable of causing a processor of a computing device 18, in connection with the pressure sensor 1, to calculate a pressure p in the combustion chamber and output pressure information depending on an effective cavity length.
  • Fig. 6 a schematic graph of a pressure curve in a combustion chamber evolving throughout an engine operating cycle is illustrated.
  • Fuel is injected into a combustion chamber of a cylinder of an engine at ti nj ⁇ Due to the motion of the cylinder head, the cylinder pressure in the combustion chamber increases. Ignition of the fuel fed into the combustion chamber takes place at ti gn before reaching the maximum cylinder pressure. Then the cylinder pressure decreases until the end of the operating cycle.
  • the continuously or step-wise measured pressure p can be displayed by means of a computing device 18. Displaying of the pressure information may take place in real time and the information may be additionally stored.
  • the pressure sensor may further be connected to another system, for example to a fuel pump, in order to continuously or step ⁇ wise provide pressure input data to the other system.
  • the invention is in particular not limited to a pressure-measuring plug for a diesel engine with a plug body for insertion into a cylinder head of the diesel engine.
  • the invention can be also used for other applications .

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

Abstract

La présente invention concerne un capteur de pression (1) comprenant un émetteur à ultrasons (2), et une cavité (3) agencée en connexion avec celui-ci, qui est dans un mode de résonance à une fréquence ultrasonore utilisée, et le capteur (1) comprenant une membrane de flexion (5), située à l'extrémité opposée de la cavité (3) par rapport à l'émetteur à ultrasons (2), et l'émetteur à ultrasons (2) comprenant un oscillateur à membrane conçu pour fonctionner soit à une fréquence de résonance d'une membrane, soit au-dessous, lequel oscillateur est relié au milieu environnant, et le capteur (1) contient des moyens permettant de mesurer l'interaction entre l'émetteur à ultrasons (2) et la cavité (3), et une carte de circuit imprimé (4) d'isolation thermique est disposée entre l'émetteur à ultrasons (2) et une carte de circuit de lecture (7), la carte de circuit imprimé (4) d'isolation thermique étant conçue pour provoquer un gradient de flux à température négative dans une direction à partir de l'émetteur à ultrasons (2) vers la carte de circuit de lecture (7).
PCT/FI2015/050508 2014-08-15 2015-07-21 Capteur de pression Ceased WO2016024041A1 (fr)

Applications Claiming Priority (2)

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FI20145723 2014-08-15
FI20145723A FI125492B (en) 2014-08-15 2014-08-15 pressure sensor

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WO2016024041A1 true WO2016024041A1 (fr) 2016-02-18

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107582101A (zh) * 2016-07-06 2018-01-16 韦伯斯特生物官能(以色列)有限公司 确定组织厚度
CN112445270A (zh) * 2019-08-16 2021-03-05 华为技术有限公司 终端的按键结构和终端
WO2023025485A1 (fr) * 2021-08-27 2023-03-02 Endress+Hauser SE+Co. KG Capteur de pression, en particulier pour des pressions supérieures à 100 bars

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4500864A (en) 1982-07-05 1985-02-19 Aisin Seiki Kabushiki Kaisha Pressure sensor
US5714680A (en) 1993-11-04 1998-02-03 The Texas A&M University System Method and apparatus for measuring pressure with fiber optics
US20080073998A1 (en) 2006-09-26 2008-03-27 Denso Corporation Ultrasonic sensor
WO2009071746A1 (fr) 2007-12-05 2009-06-11 Valtion Teknillinen Tutkimuskeskus Dispositif de mesure de pression, de variation de la pression acoustique, d'un champ magnétique, de l'accélération, de la vibration, ou de la composition d'un gaz
CN201561837U (zh) * 2009-05-18 2010-08-25 刘恒 汽车、拖拉机机油压力报警传感器

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4500864A (en) 1982-07-05 1985-02-19 Aisin Seiki Kabushiki Kaisha Pressure sensor
US5714680A (en) 1993-11-04 1998-02-03 The Texas A&M University System Method and apparatus for measuring pressure with fiber optics
US20080073998A1 (en) 2006-09-26 2008-03-27 Denso Corporation Ultrasonic sensor
WO2009071746A1 (fr) 2007-12-05 2009-06-11 Valtion Teknillinen Tutkimuskeskus Dispositif de mesure de pression, de variation de la pression acoustique, d'un champ magnétique, de l'accélération, de la vibration, ou de la composition d'un gaz
CN201561837U (zh) * 2009-05-18 2010-08-25 刘恒 汽车、拖拉机机油压力报警传感器

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107582101A (zh) * 2016-07-06 2018-01-16 韦伯斯特生物官能(以色列)有限公司 确定组织厚度
CN112445270A (zh) * 2019-08-16 2021-03-05 华为技术有限公司 终端的按键结构和终端
WO2023025485A1 (fr) * 2021-08-27 2023-03-02 Endress+Hauser SE+Co. KG Capteur de pression, en particulier pour des pressions supérieures à 100 bars

Also Published As

Publication number Publication date
FI125492B (en) 2015-10-30
FI20145723A7 (fi) 2015-10-30

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