WO1998026267A1 - Procede servant a determiner l'etat defectueux d'un capteur de pression - Google Patents

Procede servant a determiner l'etat defectueux d'un capteur de pression Download PDF

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Publication number
WO1998026267A1
WO1998026267A1 PCT/JP1997/001627 JP9701627W WO9826267A1 WO 1998026267 A1 WO1998026267 A1 WO 1998026267A1 JP 9701627 W JP9701627 W JP 9701627W WO 9826267 A1 WO9826267 A1 WO 9826267A1
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WO
WIPO (PCT)
Prior art keywords
sensor
pressure
container
voltage
vacuum
Prior art date
Application number
PCT/JP1997/001627
Other languages
English (en)
Japanese (ja)
Inventor
Toshihisa Matsui
Tomio Matsui
Masahiro Ueda
Atsuo Irisa
Original Assignee
Hokkei Industries L.T.D.
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 Hokkei Industries L.T.D. filed Critical Hokkei Industries L.T.D.
Publication of WO1998026267A1 publication Critical patent/WO1998026267A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
    • G01L27/007—Malfunction diagnosis, i.e. diagnosing a sensor defect
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/40—Investigating fluid-tightness of structures by using electric means, e.g. by observing electric discharges

Definitions

  • the present invention relates to a method for judging pass / fail of a vacuum leak of a strain gauge type pressure sensor.
  • a strain gauge type pressure sensor is indispensable as a vacuum sensor for, for example, increasing the efficiency of an automobile engine.
  • This type of normal pressure sensor detects the pressure difference between the internal high vacuum area and the external pressure introduction pipe by means of a piezoelectric element installed in a vacuum insulated manner between the two. The value is amplified as an electrical signal and extracted.
  • the degree of vacuum inside the container during manufacture is usually 6.7 Pa (0.05 Torr) or less, and the durability of the vacuum sensor is 20 years or more. That is, the maximum allowable vacuum leak rate of this type of pressure sensor has been put into practical use, 1. It is said to require 0 X 1 0- 5 P a * cc Z seconds or less.
  • the current general inspection method is to seal the pressure sensor in a radioactive material pressurized kettle for several days, and if a vacuum leak occurs, the radioactive gas is sucked. It is usually called the radio method, in which measurement is made with a Geiger counter or the like to determine the quality or vacuum leak rate.
  • the present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the conventional determination method using radioactivity. Instead, it is possible to estimate practically a wide range from both discharge and electrical output characteristics for vacuum leaks and electrical circuit defects, and to determine the quality of pressure sensors easily, safely, accurately, non-polluting and economically.
  • the purpose is to provide. Disclosure of the invention
  • the present invention proposes a new method for measuring the internal pressure of a pressure sensor container as described above, and the present invention is based on, in principle, Paschen's law that the firing voltage depends on the degree of vacuum inside the container. Based on (Paschen's Law), it is possible to instantaneously measure the degree of vacuum inside a sensor-vessel from the discharge starting voltage of the first pulse, without changing the state inside the sensor-vessel. It proposes a method that can determine pass / fail.
  • the method for judging the quality of a pressure sensor according to the present invention is based on a strain gauge type pressure sensor that measures pressure by a strain voltage generated by a difference between a degree of vacuum inside a sensor container and a pressure applied to a pressure introducing unit. This is a method of judging pass / fail.
  • a pressure sensor in which the positive electrode side of a power supply that generates a DC high voltage is connected to a terminal having all electrodes short-circuited through a resistor having a high resistance value, and a pressure sensor having a sensor and a container grounded, is connected to air, Put in a container filled with He gas or a mixed gas of He gas and air, apply a DC high voltage between the terminal and the sensor container, and discharge current generated by the degree of vacuum in the sensor container The vacuum pressure inside the sensor container is measured from above, and the measurement is repeated after a predetermined period. If the average pressure change rate during the period exceeds a predetermined value, it is determined that a vacuum leak has occurred and the defective product is determined. To judge.
  • the application of the DC high voltage is controlled so that the discharge is performed for one pulse. Therefore, at the start of voltage application, the applied voltage is slowly varied, and the voltage application is turned off by the one-pulse discharge. Further, the resistance value of the high-resistance resistor interposed between the positive electrode side of the power supply and the terminal in which all the electrodes are short-circuited is set so that the discharge current does not destroy the circuit in the sensor container. To be selected.
  • the principle adopted by the present invention for measuring the vacuum pressure of such a pressure sensor is Paschen's law as described above. As is well known, this law states that if the electric field is uniform and the temperature and humidity of the gas are constant, the minimum voltage required to cause a spark discharge is determined by the distance between the electrodes.
  • the vacuum leak rate is measured from the relationship between the discharge phenomenon and pressure. That is, since the vacuum pressure can be estimated from the discharge starting voltage or discharge current of one discharge pulse caused by the difference in vacuum pressure, the internal pressure of a sensor-vessel at a certain time is measured, and after a certain period, If the internal pressure is measured, the average rate of pressure change during this period can be obtained, and the leak rate can be obtained using the same data in relation to the internal volume of the sensor container.
  • the method for judging the quality of a pressure sensor according to the present invention requires a certain period of time before the judgment can be made, but the degree of vacuum can be instantaneously measured from the discharge starting voltage of one discharge pulse. It is a completely new method that can be measured without changing the internal state.
  • FIG. 1 is a plan sectional view (A) and a side partial sectional view (B) showing the structure of a pressure sensor to be measured.
  • FIG. 2 is a conceptual diagram showing a measurement system according to the present invention of the pressure sensor of FIG.
  • FIG. 3 is a conceptual diagram showing a model of vacuum leakage. '
  • FIG. 4 is a conceptual diagram showing the effective cross-sectional area of the hole in FIG. 3 in relation to the diameters of N 2 molecules and He molecules that can pass through a hole having a circular cross section.
  • FIG. 5 is a cross-sectional view conceptually showing a configuration of an experimental apparatus for verifying the present invention.
  • FIG. 6 is a graph showing an experimental result of a relationship between a discharge voltage and a sensor internal pressure.
  • FIG. 7 is a waveform diagram showing a discharge pulse waveform due to voltage application in the experimental apparatus of FIG.
  • FIG. 8 is a diagram showing the relationship between the sensor internal pressure and the minimum sensitivity.
  • FIG. 9 is a diagram showing experimental results comparing the amount of vacuum leakage in air and the amount of vacuum leakage in He gas.
  • a structural example of a strain gauge type pressure sensor to be determined in the present invention will be described with reference to FIG.
  • a plurality of electrode pins 2 and a pressure introducing pipe 3 are provided on a base 1a so as to be electrically insulated from each other.
  • a metal diaphragm 4 is attached to a tip of the pressure introducing pipe 3, and a diaphragm 4 is provided.
  • a piezoelectric element and an IC circuit (hereinafter simply referred to as an IC circuit) 5 are provided on the surface of, and wiring is performed between the IC circuit 5 and the electrode pins 2, and the upper part thereof is covered with a metal container 6. It is.
  • such a pressure sensor 11 is placed in a container filled with He gas or a mixed gas of He gas and air, and according to Paschen's law, from the relationship between the discharge phenomenon and the pressure, Measure the vacuum leak rate. That is, if the internal pressure Pi of the pressure sensor 11 at a certain time 1 is measured, and then the internal pressure P 2 after a certain period T (seconds) is measured, an average pressure change rate during this period is obtained. But,
  • the pressure sensor-1 of FIG. 1 is placed in a container 30 having a constant air pressure, and all the electrode pins 2 of the pressure sensor 1 1 are short-circuited to the terminal pin 2.
  • a is connected to a DC high-voltage power supply 8 via an external resistor 7, the metal container 6 is grounded via an external resistor 9 and an ammeter ( ⁇ A meter) 10, and the voltage across the external resistor 9 is observed.
  • Connect a storage oscilloscope 11 so that it is possible to record the discharge start voltage.
  • Voltmeter 12 connected as shown to the applied voltage V Q from the power supply 8.
  • the power supply 8 sets the maximum applied voltage so that an actual discharge voltage Vs (generally several hundred to several thousand V) from the electrode pin 2 of the pressure sensor 1 can be generated.
  • a computer 13 is connected to the power supply 8 as means for varying the output voltage.
  • an electromagnetic relay 14 which is turned off by one discharge current is connected to the negative side of the power supply 8, and this is grounded.
  • the present invention makes it possible to estimate the internal pressure of one sensor and one container from one discharge pulse without affecting the inside of the pressure sensor as much as possible.
  • the discharge voltage and discharge current are detected as early as possible so that the discharge can be stopped instantaneously.
  • a high resistance value of about 50 5 ⁇ is used as the external resistance 7.
  • V S V.
  • the discharge voltage between terminal 2 a and metal container 6 drops by 500 V, and the discharge stops.
  • applied voltage V. that by the power supply 8 again Is applied between the terminal 2a and the metal container 6, and the next discharge can be started.
  • the firing voltage itself does not depend on the magnitude of the external resistor 7 at all, and therefore, in practicing the present invention, it is necessary to actually connect and check resistors having various resistance values.
  • the output voltage of the power supply 8 can be changed in a desired form by the computer 13, and the voltage application from the power supply 8 is turned on and off by the electromagnetic relay 14.
  • the sudden rise in the applied voltage V 0 from the power supply 8 is a large current discharge, that is, in a short time.
  • the circuit is automatically opened by the electromagnetic relay 14 before the next discharge pulse is generated. If the electromagnet used for the electromagnetic relay 14 has, for example, a dead time of about 0.5 ms and a rise time of about 1 ms, a time delay of 1.5 ms occurs before operation starts. Therefore, the computer 13 controls the rise of the applied voltage Vo from the power supply 8 so as to match this time delay.
  • the electron emission from the electrode that triggers the discharge greatly depends on the electric field, that is, the discharge voltage if the electrode structure is determined, but sometimes because of cosmic rays or the like flying around the space. May also occur.
  • An electron emission by an electric field, immediately Chi field E mission usually occurs in 1 0 8 V / m or more electric field intensity. If the electron emitting surface has a shape like a needle tip having a diameter of about several im, the above-described strength can be easily reached even at a voltage of several hundred volts.
  • the end of the pin-shaped electrode pin 2 and the IC surrounded by the plurality of electrode pins 2 and arranged at the center thereof are represented by the following equation: m, and the distance between such a metal wire and the inner surface of the metal container 6 is 1 mm or less. is there. Moreover, even if the distance between the metal wire and the inner surface of the metal container 6 has an error of about 10%, the electric field strength may be sufficiently different by an order of magnitude, and the electron emission is an exponential function of the electric field strength. It is different.
  • the metal container 6 is grounded (ground), and the terminal 2 a in which the electrode pin 2 is short-circuited so that electrons are emitted from the metal container 6 to the electrode pin 2.
  • a positive high voltage is applied to the That is, by stabilizing the discharge start state, in other words, stabilizing the discharge start voltage by causing the electron emission to occur on the flat inner surface of the metal container 6.
  • the basic idea about the leak rate of He gas is to estimate the size of the small hole that causes the leak and to determine how much of the N 2 and He molecules, which make up the majority of the air, escape through the hole. It is to estimate.
  • one chamber 40 side is 1 atmosphere of air
  • the other chamber 41 side is vacuum
  • the partition 42 has a small leak hole 43
  • the maximum allowable leak rate of the pressure sensor is 1 X 10 " 5 Pa-cm 3 / sec. Estimate the sectional area S of the hole 43.
  • n ' pVZ (RT)
  • the maximum permissible leakage rate in the intended interest air i.e. the N 2
  • the area S against thereto the .DELTA..nu, n, v from the value of aN
  • the diameter D N of the hole in the area S shown in FIG. 4 (A) is about 10A.
  • the experimental setup for pressure measurement is configured as shown in Fig.5.
  • the base 1a of the pressure sensor 1 in which all the electrode pins 2 are short-circuited is bonded to the perforated acrylic plate 20 with an adhesive such as an aral die as shown in FIG. 2)
  • Still another through hole is connected to a He gas source (not shown) via a cock 24.
  • reference numeral 25 denotes an insulating silicone agent
  • reference numeral 26 denotes a lead wire.
  • the relationship between the sensor internal pressure P and the discharge starting voltage V was examined using the measurement circuit of FIG. 2 already described. As the ammeter 10, a 10-scale ammeter was used.
  • the discharge starting voltage and cell Fig. 6 shows an example of the relationship with the internal pressure of the sensor vessel
  • Fig. 7 shows an example of the pulse waveform at that time.
  • the results shown in FIG. 6 clearly show that the relationship between the discharge starting voltage and the internal pressure of the sensor container changes according to Paschen's law, which can be a reference for estimating the internal pressure of the pressure sensor according to the present invention.
  • the peak value of the current in one pulse discharge is about 2. 5mA (25V / 1 OX 10 3 ⁇ ), the time is about 5 seconds on average. This was converted to an average current of 12.5 ⁇ . Naturally, no needle contact was observed even when measured with a 10 ⁇ full-scale ammeter. Conversely, if pulses of the same waveform occur intermittently, for example, if a discharge current of 1 X ⁇ is observed, then 80 discharge pulses are generated per second, and the average The pulse interval time, that is, the period T is 12.5 milliseconds, and an electromagnetic relay with an operation time of 1.5 milliseconds can almost certainly stop the next pulse discharge. By the way, the energy per pulse at this time is 0.313 J, and it is not considered that the IC circuit is damaged by such energy.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biomedical Technology (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Procédé servant à déterminer l'état défectueux d'un capteur de pression, tel qu'un capteur de contrainte, en fonction de la fuite du vide. Après avoir laissé le capteur à l'air pendant une durée prédéterminée, on intercale une résistance (7) entre l'électrode positive de la source d'énergie (8) et une borne (2a), cette résistance (7) présentant une résistance sélectionnée élevée, de telle façon qu'un courant de décharge ne détruira pas un circuit intégré (5) placé dans un réservoir en métal. On relie l'électrode positive de la source d'énergie (8) à la borne (2a) à laquelle sont reliées toutes les broches d'électrode (2) du capteur de pression, on met à la masse le réservoir en métal (6) et on applique une tension élevée de courant continu entre la borne (2a) et ledit réservoir (6). On commande l'application de cette tension élevée de courant continu de la source d'énergie (8) au moyen d'un ordinateur (13), on fait varier lentement cette tension au moment de son application et on arrête cette dernière au moment de la décharge d'une impulsion. On mesure une pression vacuométrique dans le réservoir en métal (6) à partir d'un courant de décharge Id d'une impulsion en fonction de la loi de Paschen. Quand la pression mesurée de cette façon dans le capteur est supérieure à une valeur prédéterminée, on introduit le réservoir en métal (6) dans un autre réservoir (30) rempli d'un gaz He. Après l'écoulement d'une période prédéterminée, on effectue des mesures similaires afin de trouver un taux moyen de modification de pression. Quand ce taux de modification de pression est supérieur à une valeur prédéterminée, on considère que le vide fuit et on détermine que le capteur est défectueux.
PCT/JP1997/001627 1996-12-09 1997-05-14 Procede servant a determiner l'etat defectueux d'un capteur de pression WO1998026267A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/JP1996/003601 WO1998026266A1 (fr) 1996-12-09 1996-12-09 Procede permettant de determiner une acceptation/ un rejet d'un capteur de pression
JPPCT/JP96/03601 1996-12-09

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PCT/JP1996/003601 WO1998026266A1 (fr) 1996-12-09 1996-12-09 Procede permettant de determiner une acceptation/ un rejet d'un capteur de pression
PCT/JP1997/001627 WO1998026267A1 (fr) 1996-12-09 1997-05-14 Procede servant a determiner l'etat defectueux d'un capteur de pression

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016015537A1 (fr) * 2014-07-30 2016-02-04 无锡华润上华半导体有限公司 Dispositif de test de capteur de pression et son procédé d'utilisation
CN113050172A (zh) * 2021-03-12 2021-06-29 中国电建集团贵阳勘测设计研究院有限公司 一种渣库渗漏通道的电流场测试方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69738806D1 (de) * 1996-10-10 2008-08-14 Invitrogen Corp Tierzellkulturmedium mit pflanzlichen nährstoffen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53104846A (en) * 1977-02-24 1978-09-12 Fujitsu Ltd Leakage check method for reed switch
JPS5723833A (en) * 1980-07-18 1982-02-08 Hitachi Ltd Pressure sensor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53104846A (en) * 1977-02-24 1978-09-12 Fujitsu Ltd Leakage check method for reed switch
JPS5723833A (en) * 1980-07-18 1982-02-08 Hitachi Ltd Pressure sensor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016015537A1 (fr) * 2014-07-30 2016-02-04 无锡华润上华半导体有限公司 Dispositif de test de capteur de pression et son procédé d'utilisation
CN113050172A (zh) * 2021-03-12 2021-06-29 中国电建集团贵阳勘测设计研究院有限公司 一种渣库渗漏通道的电流场测试方法

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