DE3110148A1 - Device for feeding an electrically conductive medium - Google Patents

Abstract

In a potential separating device for liquid media, the liquid medium is removed from an earthed feed system (6,14) and fed, via a metering device (5), in a pulsating manner in individual amounts to a container (2) consisting of insulating material. At the same time, the feed opening (4) for the medium which is input in a pulsating manner is arranged inside a Faraday cage (7) of the earthed, electrically conductive container lid. The Faraday cage and the metering device are matched to one another in such a way that the amount of medium still inside the Faraday cage is completely separated from the feed opening. The respective amounts of medium (15) are no longer atomised in the high-voltage field so that unnecessary formation of gas and adverse influences on the medium are avoided. The device is advantageously used in potential separating devices for high-voltage paint spraying systems.

Description

description

The invention relates to a device according to the preamble of claim 1.

Such an electrically conductive, liquid medium may, for example, expectant as' 29 37 890 found in DE-P * can _ene, a paint or other coating material may be, is processed in particular for a job with an electrostatic ^ Autragsgerät for the medium.

For the potential separation with such liquid media, it is necessary to avoid short circuits between the (also from ground) grounded material feed and the high voltage ^ to prevent the application device connected to the potential, several suggestions known:

A storage container for the application material, from which the electrostatic application device is fed directly, is electrically connected to the electrostatic applicator} ^^ in order to avoid a potential difference according to VDE regulation 0147 to come up.

0 (039) 988272. . Telegnmme:

988273 Vll / WW / Wa BERGSTAPFPATENT Munich

988274 'TELEX': 933310 0524560 BEROd

Binkkonlen: Hyj "-B" nk Munich "(" 122850 (BLZ 7OO2OOI1) Swift Code: HYPO M MM Biyei Vereinst) "* Munich 453K) O 'IJl- / M Postscheck Munich 65343-80" (Bl./ 7ΆΚΛ8Ο)

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However, this has the disadvantage that a continuous coating process can only be carried out to a limited extent due to the limited capacity of the storage container. Furthermore, the arrangement has a high electrical capacity depending on the material of the storage container and the amount of application material.
2.

An "intermediate container" is provided, which is usually connected to a high-voltage or grounding device is operated to refill the supply container connected to high voltage potential from an ErtK to enable potential connected feed system.

However, this creates a high level of mechanical and electrical, sheer control effort. In addition, high electrical charge or discharge surges occur when the intermediate is recharged container. This can also assume a "flying" potential. Here, too, the refilling process is only discontinuous. borrowed possible. "~ *

In DE-P 29 37 890 a device according to the Oberbagriff is of claim 1, with which a direct, necessary continuous, supply of the order material aun a grounded supply system can be carried out in a container made of insulating material .. The b * j-

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ichriebene method of Potentai! will balance takes place after the more in detail described method of the production of electrically separated individual quantities by one, preferably electrostatic, atomization instead.

However, the supplied amount of the medium is very finely divided _F volatile components of the application material are released. On the one hand, physical and / or chemical changes in the körinen. Application material is created that changes its properties: In addition to the formation of ozone, gaseous fission products of the application material can also arise due to the atomization in the electrostatic field, which under certain circumstances generate an explosive air-gas mixture, which is a source of danger. This must therefore be made ineffective by additional ventilation devices.

It is therefore a matter of the invention to provide a potential separating device of the specified type for separating the potentials in the storage container and in the consumption container To create a medium that can work continuously and yet without unnecessarily fine division, especially around a To largely avoid gas formation, the medium is transferred from the storage container to the consumption container.

According to the invention, this object is achieved by the further development

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solved according to the characterizing part of claim 1.

“In the course of the feed line” should also be understood to mean that the metering device is arranged at the beginning or at the end of the feed line. In the latter case, the medium then emerges directly from the metering device. The metering device is preferably equipped in such a way that metering in terms of both time and quantity is possible. It is therefore possible to regulate both the quantity of the medium ejected with a pulse and the time interval between the pulses. That the respective escaping medium quantity see the area of the Faraday 'cage only leaves when it is located without connection to the outlet opening of the free fall, can be both visible through an appropriate design of the Faraday ¹ cage ,, in particular its dimensions, as indicated by the time sequence and the Determination of the quantity of the medium, i.e. ultimately by matching these factors to one another, means, in particular, that the depth of the Faraday cage is chosen so that the quantity of medium discharged from the dosing device via the supply line can fall freely without any to have a connection to the feed line is still inside the Faraday's cage.

The solution according to the invention has the particular advantage that seen in free fall from the shielding area of the Faraday

Cage falling amount of medium in the actual electrostatic Field - for example between a grounded container lid and the amount of medium at high voltage potential can no longer be electrostatically atomized at the bottom of the container despite the existing potential difference can ^ since no permanent charge equalization is possible any more is (raindrop principle). Thus, the disadvantages outlined above can no longer occur.

Preference is given in the area of the Faraday's cage, particularly preferred A grounded electrode is provided at its output. This ensures "especially if the container wall is made of non-conductive Material is formed for a defined field lines within the container: In any case, the Faraday's cage and especially the one facing the container Edge, reliably grounded.

The grounded electrode is preferred as a conductive container cover educated. In this way, the already useful container lid (reduction of the risk of contamination, if necessary Creating a closed container, see below) perform several functions in a simple manner.

The Faraday's cage is preferred as part of the container lid, particularly preferred as a protuberance arranged in its center, facing away from the direction of fall of the medium educated. The medium can then pass through the middle of the container

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lid can be inserted directly into the Faraday's cage. The manufacture of the container lid is particularly simple because it and the Faraday's cage are in one Operation can be produced; The electrostatic begins through the protuberance facing away from the inside of the container Field safe only below the Faraday's cage.

The consumption container is preferably at least above the maximum filling level of the medium made of non-conductive material educated. This limits the high voltage potential to the absolutely necessary range and reduces it There is a considerable risk of electrical flashovers between the container and the lid or the feed and the container.

• It is preferred between the Faraday's cage and the liquid level A braking and distribution device for the medium is provided in the consumption container. This facility prevents the individual portions of the medium from hitting the surface of the liquid and thus the container walls wetting splashes of the medium, which can impair the insulating effect of the container wall, arise.

A height regulation is preferably provided for the liquid level in the consumption container. This allows the Liquid level on the un-

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necessary minimum size (see below). This level control is expediently connected to the metering device. In this way, it can be prevented on the one hand that the safety distance between the medium surface and earthed parts (e.g. conductive container lid) is not undershot. In particular in the case of overpressure (see below) in the container kana, on the other hand, by preventing a level below a minimum, gas can be prevented from escaping _{, especially without an absorption buffer t.} '. ·'

The bottom area of the consumption container is preferably designed in such a way that only a small amount of the medium is present there accumulate per height unit. can. As a result, on the one hand, the height regulation can be better regulated, while on the other hand the amount of medium can be kept low.

The amount of medium in the consumption container is preferred as follows kept as small as possible. This creates the evaporation area reduced in size, only small ones remain when the system is stopped Back lacquer quantities that do not take part in the usual circulation in the ring and feed line, and the capacity, des system lying on high voltage is reduced, so. that, if necessary, safe operation with electrostatic Hand spray equipment becomes possible.

Preferably, the lid and the consumption container are designed in such a way that

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that overpressure can arise inside the container. Here, the metering device is expediently designed in such a way that that it can fulfill its function despite the prevailing overpressure. With the help of the overpressure, the medium can then be transported on to the processing point. By closing the container tightly, air can also be admitted to the Medium can be prevented. Otherwise, as an alternative, an annular gap is preferably formed between the lid and the container Ventilation of the inside of the consumption container for removal explosive solvent vapor-air mixture is used and flashovers between container and lid as well as electrical Prevents creepage distances in the case of paint deposits and paint particles from splashing out. The air gap is for example generated in that the container lid is freely suspended.

In the following the invention will be described with reference to the attached Figure explained in more detail. The figure shows schematically the entire system according to the invention.

The consumable container 2 made of electrically insulating material is also insulated and supported by a support 1. The container is designed to be narrowed in its lower area, only low in relation to the filling level Amount of medium to be taken up. Near the exit of the container

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below the intended minimum liquid level, there is an electrically conductive insert 9, which is connected to the high voltage source 18, and thus the Liquid on. Brings high voltage potential. The electrically conductive insert can also be attached to the lower part of the container be integrally formed.

The consumption container 2 is electrically conductive by a Able material, preferably metal, completed the existing lid. This container lid 3 is earthed. Between the container lid 3 and the high voltage potential Insert 9 or the liquid level 20 is an electric field, the potential gradient of which is from the The voltage level of the high voltage source depends. Between the liquid level and the container lid is located a dielectric 19, normally atmospheric air. However, another insulating gaseous medium can also be used used, which serves to contribute to the emergence of a. Spark flashover explosive solvent vapor-air mixture to avoid. As mentioned at the beginning, the lid can in particular be connected to the container in such a way that a overpressure can build up. The container lid is in his middle area, as indicated in the drawing, formed into a Faraday's cage 7. In the Faraday "See the cage is the feed opening 4 of the feed line 6

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introduced. The feed line connects the feed opening with a storage container 14. In the feed line 6 there is a metering device / the amount of medium dispensed by the pulsating metering device 5 (indicated by "raindrops" 15) per pulse is with the dimensions of the Faraday's cage and the arrangement the feed opening therein so that, as mentioned, the depth of the Faraday ¹ see cage allows the amount of medium expelled by the dosing device to be in free fall within the Faraday cage without a connection to the feed line.

The feed line 6, the metering device 5 and the supply Container 14 are, like the container lid 3, with ground potential tied together.

To when the liquid medium amounts 15 impinge on the Liquid level 20 in the lower area of the container to avoid splashing are above the liquid level Abbrems- .und Vertex1 elements 8 from mainly insulating Material attached. These have the shape of cones or grids, for example, and are arranged regularly.

By the volume of the amount of liquid that has accumulated on the bottom of the container on the one hand as small as possible, on the other hand keeping it as constant as possible, the liquid level is kept via a control device 10, e.g. with a pneumatic

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matic pressure load cell works, monitored. From this uber- ^ Fashungseinriσhtung the metering device 5 can be controlled which is also influenced by this parameter. Thus, the liquid level in the container can be adjusted accordingly .controlled: ■

the line 11 is with the help of a Isölierwelle The metering pump 12 driven by a drive 13 transfers the medium via the further line 16 of a processing device fed to high voltage potential 17. This can, for example, be a 'spray organ such as a bell, disk or Gun, be. Lines 11 and 16 and the medium pump and the processing device 17 are also conductively connected to the high voltage source.

In the system described, the equipotential bonding takes place between the individual quantities of medium supplied via the earthed cover and the amount of medium at high voltage potential located on the container bottom by charge equalization during the free fall of the individual amounts of medium instead of. -.-...

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Claims (1)

P.O. Box 860245 8000 Munich 86 Additional patent to; P 29 37 890.3-52 Ransburg GmbH
6056 Heusenstamm Device for supplying an electrically conductive medium Claims 1o device for supplying an electrically conductive, liquid medium from a grounded storage system to a Consumption supply lying at high voltage potential in a consumption container, with the supply of the consumption container a line emanating from the storage system, which is above the maximum fill level of the consumable storage ends in the consumption memory, and a device for dividing the supplied amount of medium into electrically separate Individual quantities are provided, in particular according to DE-P 29 37 890, characterized in that that the device for dividing the amount of medium supplied as a metering device arranged in the course of the supply line (6) 0 (039) 988272 vaju / ""' ^ηα telegrams: 988273 BERGSTAPF PATENT Munich 988274 TELEX! 983310 052456OBERGd Bank accounts: Hypo-Bink Munich 4410122850 (BLZ 70020011) Swift Code: HYPO DE MM Biyec Vereinsbank Munich 453100 (BLZ 70020270) Post check Munich 65343-808 (BLZ 70010080) 3110H8 device (5) is formed, that the outlet opening (4) for the metered amount of media (15) is inside a Faraday's cage (7), and that the metering device (5) discharges the medium dosed from the outlet opening (4) so that the respectively exiting Media amount (15) the area of the Faraday's cage (7) only leaves when it is in free fall without connection to the outlet opening (4). 2. Apparatus according to claim 1, characterized in that in the area of the Faraday cage (7), preferably on its Output,. A grounded electrode is provided. 3. Apparatus according to claim 2, characterized in that the grounded electrode is designed as a conductive container lid (3) is. 4. Apparatus according to claim. 3, characterized in that · (3 preferably as arranged the Faraday'sehe cage (7) as part of the container lid at its center, from the case · direction of the medium (15) facing away from protuberance is det ausgebil ^". · 5. Device according to one of claims 1 to 4, characterized 3-Ί10.Η8 ^[ ί »Et that the consumption container (2) at least above the maximum filling level (20) of the medium from non- ' conductive material is formed. 60 device according to one of claims 1 to 5, characterized marked that between the Faraday cage (7) rad the liquid level (20) in the "consumption container (2) Braking and distribution devices (8) for the medium (15) are provided, ''. ' . . 7.0 Device according to one of claims 1 to 6, characterized characterized in that a height regulator (10) is provided for the liquid level (20) in the consumption container (2) istο ■ ■ ■ ■ 8 "Device according to one of claims 1 to 7, characterized characterized in that the bottom area of the consumption container (2) is designed so that there is only a small amount of the medium (20) can accumulate per height unit. 9 ο Storage device according to one of the. Claims 1 to 8, characterized characterized in that the amount of medium (20) in the consumption container (2) is kept as small as possible. ΙΟ »Device according to one of claims 3 to 9, characterized - 4th 31-08 characterized in that the lid (3) and the consumable container (2) are designed so that inside the container overpressure can arise.