FR2675894A1 - Contactless sensor, using capacitive means, capable of operating in a contaminated medium - Google Patents

Contactless sensor, using capacitive means, capable of operating in a contaminated medium Download PDF

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Publication number
FR2675894A1
FR2675894A1 FR9106238A FR9106238A FR2675894A1 FR 2675894 A1 FR2675894 A1 FR 2675894A1 FR 9106238 A FR9106238 A FR 9106238A FR 9106238 A FR9106238 A FR 9106238A FR 2675894 A1 FR2675894 A1 FR 2675894A1
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France
Prior art keywords
capacitive
active electrode
liquids
operating
sensor
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FR9106238A
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FR2675894B1 (en
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Leteurtre Jean
Robert
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

Contactless sensor, using capacitive means, capable of operating in a contaminated medium (dusts, slivers, liquids, etc.). The invention relates to a type of sensor: capacitive sensors making it possible to carry out dimensional measurements despite the presence of dusts or liquids (water, cutting liquids, etc.) which ordinarily prevent this type of measurement. These sensors have the characteristic feature that they have an orifice situated in, or close to, the active electrode and that pressurised air or dielectric liquid is sprayed through this orifice. This spray of air or insulating liquid defines the interelectrode medium and allows the capacitive measurement of the distance between the active electrode and the opposite target.

Description

Description
Capteur sans contact, par moyen capacitif, susceptible de mesurer des distances en milieu sale (liquides, poussières....).Description
Non-contact sensor, by capacitive means, capable of measuring distances in dirty environments (liquids, dust, etc.).

Domaine technique: ce nouveau type de capteurs est capable d'effectuer des mesures en milieu industriel et spécialement dans les machines-outils. Technical field: this new type of sensor is capable of performing measurements in an industrial environment and especially in machine tools.

Etat de la technique antérieure les capteurs capacitifs ne pouvaient jusqu'à présent fonctionner qu'en milieu propre. Seuls les capteurs inductifs pouvaient effectuer des mesures dimensionnelles sans contact ; leurs inconvénients sont leur précision plus faible et leur calibration qui varie avec la composition chimique de la cible. State of the art Capacitive sensors could only operate in clean environments until now. Only inductive sensors could perform non-contact dimensional measurements; their disadvantages are their lower precision and their calibration which varies with the chemical composition of the target.

Exposé de l'invention l'invention consiste à munir le capteur capacitif de moyens qui permettent de définir le milieu diélectrique entre l'électrode du capteur et l'objet visé qui est l'autre électrode du condensateur formé. Disclosure of the invention the invention consists in providing the capacitive sensor with means which make it possible to define the dielectric medium between the electrode of the sensor and the target object which is the other electrode of the capacitor formed.

Le milieu diélectrique inter-électrodes peut être soit de l'air, soit un liquide diélectrique (par exemple une huile). L'air est préférable en ce que 1) il est facile à trouver, 2) il ne pose aucun problème d'évacuation, 3) il chasse efficacement les liquides ou les poussières, surtout si l'on utilise un écoulement sonique, 4) la constante diélectrique varie très peu avec la température ( -2 ppm /"C).  The inter-electrode dielectric medium can be either air or a dielectric liquid (for example an oil). Air is preferable in that 1) it is easy to find, 2) it does not pose any problem of evacuation, 3) it drives out liquids or dust effectively, especially if one uses a sonic flow, 4) the dielectric constant varies very little with temperature (-2 ppm / "C).

Quels sont ces moyens susceptibles de définir le milieu diélectrique inter-électrodes?
Ces moyens consistent à injecter l'air (ou le liquide) à proximité de l'électrode active, c'est-à-dire de l'électrode de mesure du capteur.What are these means likely to define the inter-electrode dielectric medium?
These means consist in injecting air (or liquid) near the active electrode, that is to say the sensor measurement electrode.

Cette injection d'air ou de liquide peut être effectuée via un orifice situé dans l'électrode active ou à proximité de cette.électrode. This injection of air or liquid can be carried out via an orifice located in the active electrode or near this electrode.

Description d'un mode de réalisation une réalisation particulière de l'invention a été obtenue en transformant l'électrode active du capteur capacitif en une buse sonique d'éjection d'air comprimé. Dans une autre réalisation, outre la base située au milieu de l'électrode active, on a ajouté des buses en amont de l'électrode active : celles-ci se comportent comme l'étrave d'un navire en écartant les gouttes de liquide qui, par leur présence entre l'électrode active et l'objet à mesurer, interdiraient la mesure capacitive. Cette méthode a fait la preuve expérimentale de la possibilité de bonnes mesures capacitives en milieu très pollué, comme le milieu machine-outil.  Description of an embodiment a particular embodiment of the invention has been obtained by transforming the active electrode of the capacitive sensor into a sonic nozzle for ejecting compressed air. In another embodiment, in addition to the base located in the middle of the active electrode, nozzles have been added upstream of the active electrode: these behave like the bow of a ship by spreading the drops of liquid which , by their presence between the active electrode and the object to be measured, would prohibit capacitive measurement. This method has demonstrated experimentally the possibility of good capacitive measurements in a highly polluted environment, such as the machine-tool environment.

Claims (3)

REVENDICATIONS 1) Dispositif de mesure capacitive des distances ou capteur capacitif dimensionnel caractérisé en ce qu'il comporte un ou plusieurs orifices (buses) dans l'électrode active, ou à proximité de l'électrode active, orifice(s) par le(s)quel(s) est éjecté un fluide homogène mis sous pression. 1) Capacitive distance measurement device or dimensional capacitive sensor characterized in that it comprises one or more orifices (nozzles) in the active electrode, or near the active electrode, orifice (s) through the (s) which (s) is ejected a homogeneous fluid pressurized. 2) Dispositif selon la revendication 1, caractérisé en ce que le fluide est de l'air comprimé. 2) Device according to claim 1, characterized in that the fluid is compressed air. 3) Dispositif selon la revendication 1, caractérisé en ce que le fluide est de l'air comprimé sous pression assez élevée pour que l'écoulement dans la buse soit sonique.  3) Device according to claim 1, characterized in that the fluid is compressed air under pressure high enough for the flow in the nozzle to be sonic.
FR9106238A 1991-04-29 1991-04-29 CONTACTLESS SENSOR, BY CAPACITIVE MEANS, LIKELY TO OPERATE IN DIRTY ENVIRONMENT. Expired - Fee Related FR2675894B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR9106238A FR2675894B1 (en) 1991-04-29 1991-04-29 CONTACTLESS SENSOR, BY CAPACITIVE MEANS, LIKELY TO OPERATE IN DIRTY ENVIRONMENT.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR9106238A FR2675894B1 (en) 1991-04-29 1991-04-29 CONTACTLESS SENSOR, BY CAPACITIVE MEANS, LIKELY TO OPERATE IN DIRTY ENVIRONMENT.

Publications (2)

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FR2675894A1 true FR2675894A1 (en) 1992-10-30
FR2675894B1 FR2675894B1 (en) 1997-08-01

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Application Number Title Priority Date Filing Date
FR9106238A Expired - Fee Related FR2675894B1 (en) 1991-04-29 1991-04-29 CONTACTLESS SENSOR, BY CAPACITIVE MEANS, LIKELY TO OPERATE IN DIRTY ENVIRONMENT.

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1914876B2 (en) * 1969-03-24 1978-03-02 Messer Griesheim Gmbh, 6000 Frankfurt Device for protecting an arrangement for capacitive distance measurement
FR2561672A1 (en) * 1984-03-21 1985-09-27 Travaux Milieu Ionisant Electrolysis device usable especially for radioactive decontamination of metal surfaces
JPS6187319A (en) * 1984-10-05 1986-05-02 Hitachi Ltd Chemical vapor phase film forming equipment using plasma

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1914876B2 (en) * 1969-03-24 1978-03-02 Messer Griesheim Gmbh, 6000 Frankfurt Device for protecting an arrangement for capacitive distance measurement
FR2561672A1 (en) * 1984-03-21 1985-09-27 Travaux Milieu Ionisant Electrolysis device usable especially for radioactive decontamination of metal surfaces
JPS6187319A (en) * 1984-10-05 1986-05-02 Hitachi Ltd Chemical vapor phase film forming equipment using plasma

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 10, no. 259 (E-434)(2315) 4 Septembre 1986 & JP-A-61 087 319 ( HITACHI LTD ) 2 Mai 1986 *

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FR2675894B1 (en) 1997-08-01

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