WO1985000425A1 - Installation de mesure de la pression d'un milieu gazeux - Google Patents

Installation de mesure de la pression d'un milieu gazeux Download PDF

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Publication number
WO1985000425A1
WO1985000425A1 PCT/DE1984/000114 DE8400114W WO8500425A1 WO 1985000425 A1 WO1985000425 A1 WO 1985000425A1 DE 8400114 W DE8400114 W DE 8400114W WO 8500425 A1 WO8500425 A1 WO 8500425A1
Authority
WO
WIPO (PCT)
Prior art keywords
oscillator
gas
pressure
cavity
signal
Prior art date
Application number
PCT/DE1984/000114
Other languages
German (de)
English (en)
Inventor
Gerhard BRÜGGEN
Dieter Karr
Wolfgang Rottler
Ilan Brauer
Original Assignee
Robert Bosch Gmbh
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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO1985000425A1 publication Critical patent/WO1985000425A1/fr

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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
    • G01L9/0001—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
    • G01L9/0022—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations of a piezoelectric element

Definitions

  • the invention relates to a device for measuring the pressure of a gaseous medium according to the preamble of the main claim.
  • a closed device is known from DE-OS 31 26 6 1 5, with the aid of which the pressure of a gas can be measured with a power balance which acts on a piezoelectric element. It is a closed system, the accuracy of which depends to a large extent on the tightness of the arrangement and which furthermore has only a limited measuring range in accordance with the deformability of the pressure cell. Furthermore, when a pressure cell is deflected, there is a nonlinear relationship between the electrical signal and pressure, which can impair the accuracy of the measurement result.
  • the device according to the invention with the characterizing features of the main claim has the advantage that a robust and precise measuring system is created with little equipment. Because of its compact design, the device is particularly suitable for use in motor vehicles, and because of the large measuring range, different types of applications can be implemented without additional measures. Particularly advantageous fields of application in this connection are the measurement of the intake pressure of the gasoline-air mixture in internal combustion engines in the range below 1 bar, the measurement of the tire pressure in the 3-range from approximately 1 to 5 bar and the measurement of the gas pressure in pneumatic brake systems. system, where pressures in the range of 1 5 to 20 bar occur.
  • piezo-flexural oscillators are preferably suitable, which deliver a relatively strong output signal in a compact design, but are instead, it is also possible to use thick-wing or shear-wing vibrators.
  • the design of the device it is expedient if either the cavity for the gas volume to be measured and the opening channel are machined out of metallic carrier disks for the transducers, or a slotted washer is used as a spacer disk, the slot defining the gas supply channel.
  • the device can be assembled in a particularly simple manner by welding along the edge of the carrier disks.
  • Electrical compensation is particularly suitable for eliminating aging and temperature influences on the piezoceramic of the measuring device in such a way that an additional feedback oscillator is provided on the same carrier plate as the first, defined excited oscillator, the output signal of the feedback oscillator in the sense of a compensation of the aging and temperature influences acts on the output signal of the device.
  • This can be done directly by representing the output signal of the measuring device as a quotient of the signals of the second oscillator and the feedback oscillator (S 2 / SR), but a compensation circuit with a difference formation is even simpler, the feedback signal (SR) via an amplifier to a Controller is given, which changes the excitation signal (S1) of the first oscillator such that the feedback signal is kept substantially constant.
  • the feedback signal (SR) also influences the signal of the second oscillator (S2) in the sense of compensating for these changes. Further details and advantageous developments of the invention are explained in more detail using the exemplary embodiment in the following description.
  • FIG. 1 shows a section through a measuring device with compensation control
  • FIG. 2 shows a plan view of the opened measuring device.
  • FIG. 1 shows a pressure measuring device with a first bending oscillator 10, a second bending oscillator 11 and a feedback oscillator 12.
  • the feedback oscillator 12 is formed by a sector of the first bending oscillator 10, which is arranged on a first carrier disk 13.
  • the second flexural vibrator 11 sits at a distance ⁇ 0.2 mm, preferably at a spacing ⁇ 0.15 mm, from the first flexural vibrator 10 on a second carrier disk 14.
  • the distance between the flexural vibrators 10 and 11, or between their carrier disks 13 and 14 is defined by a slotted metal washer 15.
  • a channel 16 with a gap width of 0.03 to 0.3 mm 2 is formed through the slot in the annular disc 15, through which the to be measured
  • the channel 16 is executed with a length of 1 to 2 mm, so that pressure changes in the cavity IT between the carrier disks 13 and 14 have a full effect on the second bending oscillator 11 with very little pressure reduction to the outside.
  • An annular one is seated on the first carrier disk 13
  • the cavity 17 for receiving the measuring gas has a volume of 5 to 10 mm 3 in the pressure measuring device shown.
  • FIG. 1 also shows a circuit arrangement for compensating for aging and temperature influences on the bending oscillators 10 and 11.
  • a sector is separated from the bending oscillator 10 as a separate feedback oscillator 12, the output signal of which serves as a controlled variable.
  • the device is excited by a sine generator 19 with an operating frequency between 1.5 and 6 kHz, the output signal of which is given to one input of an operational amplifier 20.
  • the control signal of a controller 21 At the other input of the operational amplifier 20 is the control signal of a controller 21, which receives the feedback signal SR as an input signal via an amplifier 22.
  • the first bending oscillator 10 is then excited from the output of the operational amplifier 20 by the signal S1.
  • the output signal S2 of the second flexural oscillator 11 passes through an amplifier 23 and a switching element 24 to the analog output 25 of the measuring device.
  • the switching element 2 h is essentially used to calibrate the output signal S2 and for 3 calibration switching according to the size of the output signal.
  • a voltage analogous to the pressure in the cavity 17 can be tapped at the analog output 25.
  • Figure 2 shows a plan view of the open measuring device, the slotted washer 15 and the channel 1 6 formed by the slot for the passage of the sample gas are particularly clearly recognizable.
  • the annular disk 15 sits on the second carrier disk 14 and closes off from the outside thereof, the second bending oscillator 11 is indicated by dashed lines.
  • a cavity 17 is delimited by two opposite walls, one of which produces pressure fluctuations similar to an oscillating piston and the other wall measures the pressure fluctuations in the manner of a microphone.
  • two identical piezo-ceramics are used on both sides of the cavity 1T in the measuring arrangement, which are located closely opposite one another and are designed as plate-type oscillators 10 and 11.
  • the first flexural oscillator 10 is excited by a sinusoidal voltage signal to defined vibrations
  • the second flexural oscillator 11 is triggered by the gas cushion located in between and vibrates passively.
  • a vibration-proportional voltage signal S2 is then taken from the piezo ceramic of the second bending oscillator 11.
  • the arrangement is open via channel 16 and thus overload-proof. Since the cavity 17 is connected to the measurement gas via the channel 16, the measured pressure fluctuations are proportional to the measurement gas pressure outside the cavity when the surface of the first bending oscillator 10 oscillates with a constant amplitude.
  • the size of the piezoceramic bending vibrators 10 and 11 determine the size of the pressure sensor.
  • bending vibrators 10 and 11 were used with a ceramic diameter of 8.5 mm and an outer diameter of the carrier disks 13 and 14 of 12.5 mm, which at the same time determine the outer diameter of the overall device.
  • the excitation through the sine generator 19 took place in the frequency range between 1, 5 and 6 kHz, whereby tests were carried out in the vacuum range between 0, 2 and 1 bar. In this pressure range there is a very good linearity with an error ⁇ 2% of the initial pressure 1 bar.
  • the use of the measuring device is not limited to this pressure range, since it is overload-proof as a partially open system and can therefore also be used for any higher pressures.
  • the speed of the pressure measurement system used in the tests was at a cut-off frequency of approximately 60 Hz, which, however, can be adjusted via the cross section of the channel 16.
  • the channel i ⁇ is narrow so that, in a first approximation, there is no pressure compensation through the channel 16 during the measuring process.
  • the pressure chamber in the form of the cavity 1T has a constant area on the excitation side, which in turn oscillates with a constant amplitude.
  • the volume of the cavity 17 is periodically varied by the movement of the bending oscillator 10, the static pressure P o des
  • Measuring gas also prevails in the cavity 17.
  • the change in volume due to the movement of the bending vibrator. 10 now causes an alternating pressure which is variable with the frequency of the generator 19 and which is measured with the second bending oscillator 11. Since the radiation surface of the first bending oscillator 10, the volume of the cavity 17 and the amplitude of the oscillation of the first bending oscillator 10 are constant, the alternating pressure is proportional to the static pressure P o , so that the measurement of the alternating pressure on the second oscillating oscillator 11 for determining the static pressure in Cavity 17 can be used.
  • the type of attachment of the flexural vibrators to the excitation of the gas cushion is also noticeable.
  • the structure-borne noise coupling can be reduced by the type of fixation.
  • the material of the washer 15 also plays a role here.
  • metal washers in particular, have proven useful, since advantageous washers 15 made of paper or plastic have not proven to be stable in the long term in short-term tests.
  • Metal washers 15 also have the advantage that the manufacture of the device is particularly simple by directly welding the support washers 13 and 14 to the washer 15.
  • the arrangement of the support washers 13 and 14 and the washer 15 is advantageously used as a damping mass Welded 18 acting ring, which is part of the bracket, not shown.
  • the first 3ie vibrator 10 is mechanically coupled to a feedback oscillator 12 and integrated into the electronic circuit in such a way that the transmitter flexural oscillator 10 is acted upon by a regulated signal S1 such that a constant voltage signal SR is always set at the feedback. So that the aging and temperature influence of the piezo-ceramic is canceled because both influences act both on the ceramic of the feedback oscillator 12 and on the receiver ceramic of the bending oscillator 11.
  • the controller 21 carries out a slow-running proportional control, the operational amplifier 20 being controlled such that the output signal S1 of the operational amplifier 20 is increased as the signal SR becomes smaller.

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

Abstract

Installation piézoélectrique pur mesurer la pression d'un milieu gazeux. Deux résonateurs de flexions (10, 11) se faisant force sont disposés dans un système largement fermé sous l'influence du gaz à mesurer. La mesure est effectuée par détermination du facteur de transfert du premier résonateur piézoélectrique (10) au second résonateur piézoélectrique (11), le premier résonateur piézoélectrique étant excité d'une manière définie et le signal de mesure étant tiré du second résonateur piézoélectrique (11).
PCT/DE1984/000114 1983-07-13 1984-05-19 Installation de mesure de la pression d'un milieu gazeux WO1985000425A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP3325188.6 1983-07-13
DE19833325188 DE3325188A1 (de) 1983-07-13 1983-07-13 Vorrichtung zur messung des druckes eines gasfoermigen mediums

Publications (1)

Publication Number Publication Date
WO1985000425A1 true WO1985000425A1 (fr) 1985-01-31

Family

ID=6203816

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1984/000114 WO1985000425A1 (fr) 1983-07-13 1984-05-19 Installation de mesure de la pression d'un milieu gazeux

Country Status (5)

Country Link
EP (1) EP0149620A1 (fr)
JP (1) JPS60501823A (fr)
DE (1) DE3325188A1 (fr)
IT (1) IT8422547V0 (fr)
WO (1) WO1985000425A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2722560A1 (de) * 1976-06-08 1977-12-22 Akad Wissenschaften Ddr Verfahren und vorrichtung zur kontinuierlichen messung von gasdruecken
FR2504265A1 (fr) * 1981-04-15 1982-10-22 Detaint Jacques Dispositif de mesure de la pression d'un gaz

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS539875B2 (fr) * 1973-12-12 1978-04-08

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2722560A1 (de) * 1976-06-08 1977-12-22 Akad Wissenschaften Ddr Verfahren und vorrichtung zur kontinuierlichen messung von gasdruecken
FR2504265A1 (fr) * 1981-04-15 1982-10-22 Detaint Jacques Dispositif de mesure de la pression d'un gaz

Also Published As

Publication number Publication date
EP0149620A1 (fr) 1985-07-31
JPS60501823A (ja) 1985-10-24
DE3325188A1 (de) 1985-01-24
IT8422547V0 (it) 1984-07-11

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