DE2702004A1 - DEVICE FOR DETERMINING THE DEGREE OF FOAMING IN A FLUID OR EMULSION - Google Patents

Description

Cologne, January 17th, 1977 V ^.

S (LIVERPOOL)

LIMITED, Lune Buildings, Lawrence Road, Liverpool L15 3HB, nerseyside, england

Hein sign: Ii 152/1

Vorrjflitun /; to determine the rigging wheel in a fluid or an emulsion

The present invention relates to a device for determining a predetermined degree of foaming in a fluid or an emulsion.

In a washing machine, the presence of foam is an indicator about the cleaning power of the V. ash fleet. If there is too little foam, the contaminants will not be kept at bay. Instead of of which they settle on the goods to be washed. If there is too much foam, on the other hand, not only is Viasch material wasted, but also reduces the effectiveness of the washing process, since the mechanical intervention between the good parts to be washed is reduced to an insufficient level. The supervision the degree of foaming of the wash liquor is therefore desirable. Then their cleaning power can be used during the entire 1 * ash process keep it at an effective level.

According to the invention it has been found that an accurate indication of the amount of fluid in a fluid or a Emulsion containing foam, hereinafter referred to as the degree of foaming, can thereby achieve that the fluid to be monitored or the emulsion to be monitored as a dielectric one Capacitor is used and its capacitance is compared with that of a reference capacitor.

Devices operating according to this principle are already known for regulating the depth of a fluid. For example, US Pat. No. 3,397,715 discloses a device for regulating the

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• .stands of fluids or, cornföriai ^ .en solids known in a container. This device contains a probe that forms a capacitor together with the container wall, the dielectric of which consists of the contents of the filter. At one with _'f ater-filled container, the effective dielectric constant varies in Gesarnt jjehältergebiet between the probe and the associated container wall as a function of volume and thus the depth of the contained in the container, Asher. This known device contains an ILF oscillator. This is connected to a kaOcity control circuit via a transformer,

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the a .öetäti ^ un ^ ssi ^ nal for / a thyristor controlled dosing element supplies.

Devices are also known which do not respond to changes in capacitance of a Capacitor respond as a result of fluctuations in the nature of its dielectric, but to changes the capacity due to fluctuations in the distance between the Capacitor plates react. So v / ird for example in the GB-FJ 1 169 197 a device for -e determining the approach εαι an object or a body of material described on Changes in capacitance between a fixed electrode and the subject in question o-e each xi body addresses. This device contains an oscillator which, when the object or body is missing, has a ji ^ nal with maximum amplitude and when approaching of the body or object delivers a modulated smaller one.

The task of the present iirfindunü is now the training of a Apparatus using the general technique discussed above but comparing the circuitry used to which known devices is simplified and which is especially suitable for determining certain degrees of expansion and responds to them.

According to the present invention, a device is provided with a first induction coil in the form of a bifilar winding applied to a ferrite ring core, the two sections of the bifilar winding being connected in series and the

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ORIGINAL INSPECTED

The connecting parts between these two sections are formed by the tapping of the coil, a capacitor with the formation of a parallel resonance circuit is lived over the first opule and both ends of which are connected to a specified capacitance and an electrode and thus form a capacitive element, the dielectric of which is at in . ^ peration oefindlicher / orrichtun- a scan fluid or contain emulsion to be tested, and the uittelp.nzapfun _o the first pule ^ cn the;. _c us; sn _L, one amplifier is connected, the input of which on a ¹ second detector coil which has its own winding on your core, which is located in the luitte of the two ends of the fileren winding and which is inductively coupled to the first coil, so that that prevailing between the first opule and the detector coil mutual inductance forms a feedback loop for the amplifier ur.d and finally circuit devices n are provided in order to generate an output signal after the output of the oscillation state of the amplifier.

Follow the construction of the induction coil described above and the detector lies in the fact that with equal currents in the two bifilar sections, that is, in the two Halves of the coil, the corresponding magnetic induced in the core Exactly cancel each other's flows so that the total flow established in the core is 1-iull. This is also the case the voltage prevailing in the detector coil in this operating state Zero.

Preferably, the two sections of the bifilar ..icklun ^; connected in series.

The arrangement described above has the advantage that an output signal can be obtained from the amplifier, the size of which corresponds to the amount of the fluid to be monitored contained foam is directly representative, so that one can by comparing the amplifier output signal with a preselected Proportion of a fixed reference signal the respective degree of foaming, i.e. the amount of foam present

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can select to which the device responds. By using the output signal of the device for actuating valves, the addition of detergents to the monitored Controlling fluid, the device can thus be used to precisely control the degree of foaming and thus the cleaning power of the disruptive agent according to specified standard values use.

The ¥ preferably digital output signal of the device is advantageously designed so that it is at a predetermined Output voltage or an output current of the amplifier will. The predetermined threshold voltage or the predetermined Threshold current at which the digital output signal is triggered is selected in such a way that it corresponds to a certain, in which the amount of foam contained in the fluid to be monitored.

In one embodiment of the invention, the electrode can be attached to or in a viand of a fluid canister, for example mount a washing machine, this one wall consisting of an electrically insulating material. An opposite one and waiu of the fluid chamber made of a conductive material forms a second electrode of the capacitive element. Alternatively, the first mentioned electrode is the capacitive one The element is placed in a fluid canister and a conductive wall of the chamber forms the other electrode of the capacitive one Element. In a further embodiment, the fluid or the emulsion is contained in a vessel and the first mentioned electrode is in this, while a second plate, the other electrode of the capacitive element forms, is also in this vessel.

The invention will now be described further using the example of the embodiments shown in the drawing.

In the drawing is:

Fig. 1 is a schematic representation of an inventive

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Execution form,

Fi _to . 2 shows a simplified representation of the embodiment shown in FIG. 1 with a first detector electrode arrangement,

Fi ₀ -. 3 shows a simplified representation of the execution form shown in FIG. 1 with a second detector electrode arrangement,

4 shows a simplified representation of the embodiment shown in FIG. 1 with a third detector electrode arrangement,

FIG. 5 shows a simplified representation of that shown in FIG. 1 Embodiment with a fourth detector electrode arrangement,

6 shows a schematic perspective illustration, on an enlarged scale Scale, a multiple induction winding of the in Fig. 1 shown embodiment and

Figure 7 is a graph showing the output voltage of the amplifier the embodiment shown in Fig. 1 / with changes in the degree of foaming of the fluid to be monitored or the emulsion to be monitored.

As shown in FIGS. 1 and 6, the device responds to the capacitance between a detector electrode 10 and a second fixed electrode, which can be either ground (FIGS. 2 and 5) or a second detector electrode (FIGS. 3 and 4). In the arrangement shown in Fig. 2, for example, the detector electrode 10 is shown on an outer wall 12 of a "washing machine, not shown in detail. The wall 12 is made of a suitable θ dielectric material, for example a plastic, b" and forms together with a metallic side or end wall 14 of the washing machine, the chamber 16 receiving the fluid. The wall 14 of the washing machine

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machine is at cash desk potential and forms together with the detector electrode 10 a capacitor, the capacitance of which is called Cx in the following. The fluid can come out of the washing machine Enter the l.aomer 16 via openings 13 and 20 and go through this. It goes without saying that the amount of capacity Cx from the N,?. Door of the between the fixed wall 14 of the washing machine and the electrode 10 located dielectric depends. This dielectric is formed by the ', .and 12 Material and the fluid located in the Kaiamer 16 shown. This fluid exists when the washing machine is running solely from air, a mixture of air and liquid (foam) or just from ', csser. The one to be described below The circuit of the device according to the invention is designed so that it is between these states and their various can distinguish given compilations.

The arrangement of a special chamber 16 for fluids in the washing machine is not required. Ss can be measured directly in the washing chamber of the machine. Figures 3 and 5 show such embodiments. In the embodiment shown in FIG. 5, a detector ^{electrode 22 passes through a bore 24 in the wall 14 1 of} the washing machine into the fluid contained therein. The electrode 22, which is insulated from the wall 14 'by an insulating sleeve 26, forms one electrode of the capacitor, which has the capacitance Cx, the other electrode of which is formed by the adjacent metallic wall 14 The fluid contained in the washing machine is the dielectric of the capacitor, the capacitance Cx of which depends on the nature of the fluid.

3 shows an embodiment with two detector electrodes and 30. These pass through corresponding bores in the wall 14 "through. The wall 14" consists in this case of an insulating material.

The two electrodes 28 and 30 represent the capacitor with the capacitance Cx and that in the washing machine between the two

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Ocix electrodes located otröuun ^ nittel forms the dielectric of this capacitor.

In Fi ₀ . U. 3führungsform shown ei ^ v this / ground two flat Detektcrelektroden _2 and 3 X 4 are used, .., ic are on the surface (preferably the outside of) the \ ond 14 '"ofthe" ■ - 4, another is . ..- ischnaschinö printed / jach this '..End 1':. ·· "consists of an insulating he :: stoif ..ie previously form the electrode Ξ-- and ~ j ^'L' ~ to the capacitance C ::. having capacitor, the nature of the otrörjuii ^ smittelü contained in the i-machine then determines cien I? it - .. ert of the capacitance 0 ::.

The switching of the preferred. ' uniührmv. ^: ; form is now described in detail under ::> e train on Fig. 1. Here, s is genoniuen that the detection electrode has the shape shown in Fig. 5 or in this case, is located at the one electrode of the capacitor to i-.asse.

The capacitance Jr lying between the electrode 10 and Hasse lies in a branch of a circuit which in reality represents a capacitance bridge, the other capacitive two of this bridge containing an adjustable capacitor C ₁ . The other two branches of the bridge are inductive and are formed by the two halves of an inductance K ₁ ^ tapped in their cement. Another capacitor C ₀ is located across the lands a and c of the inductance L ^ and forms with this an iarrllelresonanzkreis. A second inductance L ₀ lies next to the inductance L ₁ and is inductively coupled to it. One end d of the inductance L ₂ is at the base of a first rii ^; iI transistor Tr ₁ . The other end e is connected via a capacitor C1, en Hasse. The collector of the transistor Tr ^ is connected via a resistor ^ ₁ to a positive voltage line 56 and to the base of a second rlPil transistor Tr ₀ . Its emitter is connected _{to Hasse via a resistor R 2} and via a resistor R-, at the end e of the inductance Lo. The collector of the transistor Tr ₂ is also connected to the positive voltage line 36 via a transistor R ^ and to the toittelanzapfung 6 of the inductance L ^ via a capacitor J ^. A decoupling

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capacitor G ^ is located zv / i see the two voltage lines.

The two transistors Tr ₁ and Tr ₀ and the associated circuit elements form a generally designated in the Figures 2 to 5 with 33 amp. This v / eis a feedback loop closed by the mutual inductance between the coils L ₁ and L ₂ , which under certain circumstances leads to positive feedback. Then v / ground vibrations with approximately the resonance frequency of the parallel _{circuit L 1} , Cp generated in the Vastärker.

The two resistors R „and * U produce a grainy ο

compensating bias for the amplifier. The capacitor G ^,

ensures the alternating voltage decoupling. An additional, The capacitor, not shown, can, if necessary, be connected to ground λ '/ parallel to the resistor R ^ and increases the AC voltage amplification factor of the amplifier. This makes the circuit even more sensitive to very small changes in the between the electrode 10 and iiasse located capacitance.

The structure of the two inductances L ₁ and Lp is critical for the operation of the device. According to the illustration in FIG. 6, the inductance L _{1 is} a bifilar coil wound onto a ferrite ring core 40. The two sections of this coil are arranged in a "series support" circuit. The connection between the two sections forms the center tap b. The coil L ₁ is thus created by the parallel winding of the two wires 42 and 44 onto the core 40. The end of the wire 42 forms the connection a at one end of this pair of windings. The end of the wire 42 at the other end of the winding pair is connected to the end of the wire 44 at the first end of the winding pair to form the center connection b, and the end of the wire 44 at the other end of the winding pair forms the connection c.

_{The detector coil L 2} is located in the middle area of the section of the core 40 between the ends of the wound pair 42, 44. It thus takes a neutral position with respect to the coil L ₁

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With the bifilar nature of the two windings 42 and 44, it is ensured that the two points a and c are arranged sjTumetrically with respect to the point b. With the same currents flowing in the "." Windings 42 and 44, the magnetic flux established in the core 40 is UuIl. The same applies to the current induced in the coil L _0. This means that there is no feedback to the input of the amplifier Tr ^, Tr ₂ . This also eliminates vibrations in the amplifier. This state occurs when the capacitance between the detector electrode 10 and i-iasse is equal to the capacitance of the capacitor C ₁ . The bridge is then in equilibrium.

From the drawings it can be seen that the two halves of the coil L ₁ opposite the Kittelanzapfung b opposite zueinan are wound. This has the consequence that with the connections shown and with a capacitance of C ₁ exceeding the capacitance Cx between the detector electrode 10 and Ilasse , that is to say when Cx drops, each in the core 40 as a result of the difference between the currents in the Both halves of L-induced magnetic flux causes _{a corresponding current in the coil L 2.} However, this flows in phase opposition to the current in L. The amplifier is thus fed back and no oscillations occur.

On the other hand, if the capacitance Cx between the detector electrode 10 and ground increases so that it _{exceeds that of the capacitor C 1} , the current induced in the coil Lp is in phase _{with that in the coil L 1.} Positive feedback occurs and the amplifier is excited to oscillate. Under these circumstances, the size of the output signal of the amplifier depends on the imbalance of the bridge and thus on the amount by which the capacitance of the capacitor located between the electrode 10 and ground exceeds that of the capacitor C.

It is evident that the circuit is also in the opposite Way works just as well. When reversing the polarity of the coil connections

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Lp for example -vircl der zviochen der ,, iolctrode I ^ un: ⁿ . _: .x.sse lying capacitor C ;: smaller than the! capacitor J ₁ . The negative feedback becomes positive and the .JCrIaItUn ₀ üchv.'iiigt. ..an enlarged a'apazitai; ^ x at the electrode iü then generates a negative feedback and the wcni / ingun ^ on v / earth is interrupted.

The circuit also contains additional elements for -, production ^ eri an output signal and preferably you a visual one

This happens when the front part of the circuit described up to now generates vibrations above a predetermined threshold value. Referring to ^, to Fi ^. Let 1 be at ₀ enomraen that one of the output voltage of the amplifier 33 is proportional

Signal A is removed from the connection point between the capacitor C and the coil Li via a resistor R ^. The rectification and smoothing takes place with a diode D ^ and a capacitor Cr ₁ It was shown that between the output signal of the amplifier 3c3 and the nature of the material between the electrodes of the detector capacitor there is a certain number of draws, i.e. the circuit constants are dimensioned, for example, so that the amplifier output voltage is low when the detector electrode 10 is in dry air is, can be at a AMENDING _o the nature of the material (ochaui, i; ate ₀ e) a gradually increasing output voltage α observe the Jchaubild shown in Figure 7 illustrates this effect in these ^ chaubild, the ordinate Y ^.... output voltage A of the amplifier and the abscissa j \ die, ielative amount of air and liquid in the flow meter located at the electrode 1ü ittel. The section (i) means clean air. The section (Ii? Means water vapor, mist and the like. The section (iii) means sulcions, v / as they are formed, for example, by oil and fats in water. The section (iv) means, for example, by detergents and Soaps created foam in water and the section (v) means pure liquid, v / ie for example pure water.

The circuit also contains a threshold switch 46. This takes both the amplifier output signal α and a presettable ones to be taken off by a suitable generator 43

709829/101 7 ORIGINAL INSPECTED

^ on. * λί a Leitu.i-, yj ^ ibt this ^ chc-.Iter if the "i ^ nalc. · at his, both ... iiin ^ iui ^ eu one i.Uo ^ cai ^ sapannuii ^, εο. Jach the jjaratellun ^ in the right ^ side of Fi;.;. 7 can be determined by “dil; ler LrJGe of the tension of the j-enerator -: - cJ, ciis üiix cLe; ii ^ .us ^ cn ^ ssi ^ nal ^. de ^ Yerntdr ^ erc Tr-], Tr ₀ vert-lichen v.ircl, the e-uf der ^ citun ^, ^ O ruling optuinun ^ üo aus'.vählcn, that cie only in the presence of a certain lock / jSt-. rs.dec üviochen the .ledtroden of the ^ etelitor.condenser occurs. Ff = IIc- zuia Jeis'oiel iu Generatoi 'k'o a feote st £ .bilo Be2u _c 3 £ 7> arLnun ^ produces v / ii'd, can be before ^ ov / dhlte Jereinhe this υ ozu ^ sspannun ^ with dem jiUü ^ on ^ ssi, jnel i. des' / ertitürkeru im,. ^ chc.lter ^ J compare, so de.j this at beotimrten i.Uot; an ^ 3opannun _c : en * ,. switches on and d'ihiit «Jen ^, exvünL ^ chten / crschdumun _t _: c _o r ad? .nz ei, _. t.

Jas on line 30 Iie _f ende digital ^ UG _b on ₀ ssi _o nal can be in conventional ..eise back ^ rreveii or ^ ntei-re ^ en of one or more kelcis Vl and if necessary also a visual sign ^ evorrichtunt ö '' ^L ,., ie to the I-Eisriiel of a 'light bulb or a L ·: !!) ver \; end. The odei ¹ the .velais 5? - can be cloth in conventional., Iron to ;; ..- etdti _c en _Lj eeir, neter valve verv: enclen, ura so that .ieini _o un ₀ substances to be added until the preselected foaming rate is reached. At this point the valves are automatically closed. When falling of the '' erschäUTnun ^ ^ ssrades under the ollvert BEV; i: rkt the circuit addition v / Eiterer ii-eini un ^ ^ ^ smittel until the Verschüuraun srrad v ^r ieder on oollv / ert anicorant.

The arrangement described above can be used for identification,.; bestimiater ün ^ ^ s Ebun and eeirneter to operate ^ ^ s Auslöseschaltun verv, ^r end. The circuit arrangement can be used to generate bars for Iueß- and oteuerzv / corners, in the same way the circuit for display and. also use actuations from and for state events, for example a transition from state (iii) to state (iv). see Fig. 71

In Fig. 1 there is only a single ochv / ellv / ertschalter bzv /. one Comparison level 46 included. In certain embodiments

ORIGINAL INSPECTED 709829/1017

however, several such switches 46 can be used. Everyone Switch then speaks to other designated areas and thus also "different degrees of clandestine envisaged".

Because of ; For simplicity, the circuit elements 45, 43, 50, 52 and 54 of the embodiment shown in FIG. 1 can be mounted in a location remote from the electrode, while the other circuit elements to be assigned to the bridge circuit and the amplifier are in one unit next to or together with the detector electrode 10 mounted v. ^{r can} ground.

Ia above, the output signal A has been described as proportional to the voltage output of the amplifier Tr.-, Tr ₂ . This oi ^ nal Λ can also be proportional to the output current of the amplifier.

To avoid fading following the creation of a digital output pulse it on line 50 v / ground preferably additional circuit elements, not shown in detail, are used. These prevent the creation of another digital one Output pulse until a specified period of time has elapsed.

Men and the different designs of the invention shown in the drawings have been described above are all related to washing machines. However, the invention is not limited to the detection and display of foam in washing machines. It can also be used to determine and display the proportions of liquid and gas in any foam or emulsion.

Patent claims:

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Claims (6)

Cologne, January 17, 1977 above all. Applicant: MALCOk-ELLIS (LIVERPOOL) LIMITED, Lune Buildings, Lawrence Road, Liverpool L15 3HB, Merseyside, England Hein reference: il 152/1 PATENT CLAIMS 1.jDevice for determining the degree of foaming in a fluid or an emulsion, in which the fluid to be monitored forms at least part of the dielectric of a capacitor, the capacitance of which is compared with a predetermined reference capacitor, and with one which is responsive to a predetermined comparison state with the formation of an output signal Control circuit, characterized in that a first induction coil (L.,) in the form of a bifilar winding (42, 44) is wound onto a ferrite ring core (40), both sections of the bifilar winding are connected in series, the connection (b) of the two Sections that form the center tap of the coil, a capacitor (C ₂ ) is located above the first coil (L ₁ ) with the formation of a parallel resonance circuit, the two ends (c, a) of the first coil (L ₁ ) to a predetermined capacitance (C ₁ ) and are connected to an electrode (10) to form a capacitive element, the dielectric of which when the device is in operation contains a fluid to be monitored or an emulsion, the center tap (b) of the coil (L ₁ ) is connected to the output of an amplifier (38), the input of which is connected to a second detector _{coil (L 2} ), which has a separate winding on the core (40) which is substantially mid-way between the ends of the bifilar winding (42, 44) and which is inductive | is tively coupled to the first coil (L ₁ ), so that the mutual inductance between the first coil (L ₁ ) and | the detector coil (L ₂ ) a feedback loop for the j Amplifier (38) completed and the control circuit (46, ' M 152/1 709829/1017 48) according to the vibration state. Es (fes amplifier (38) generates an output signal. 2. Apparatus according to claim 1, characterized in that the control circuit is the combination of a rectifier and smoothing circuit (D., R _c , C_) for generating one of the size 15 5
of the output signal of the amplifier (38) contains proportional DC voltage signal, an adjustable reference voltage generator (48) is provided for generating a reference signal of adjustable magnitude, a threshold value switching device (46) with a first and a second input are provided which receive the DC voltage signal and the reference signal, respectively, the threshold value switching device (46) generates an output signal when these two signals at the inputs are equal, and a valve device (52) is provided which comes into operation in accordance with the output signal of the threshold value switching device (46) for additional quantities Add cleaning agent to increase the degree of foaming of the fluid. 3. Apparatus according to claim 1 or 2, characterized in that the first detector electrode (10) on an upright wall (12) the washing chamber of a washing machine is mounted, the wall (12) consists of an electrically insulating material, and a second detector electrode through the opposite wall (14) of the wash chamber of electrically conductive material is formed and connected to ground (Fig. 2). 4. Apparatus according to claim 1 or 2, characterized in that the first detector electrode (10) of the capacitive element is arranged in the laundry chamber of a washing machine and a second detector ^{electrode of the capacitive element through an electrically conductive wall (14 1} ) of the washing chamber (Fig. 5) is formed. 5. Apparatus according to claim 1 or 2, characterized in that the device has two detector electrodes (28, 30), both of which in the washing chamber of a washing machine 709829/1017 ne (Fig. 3) are arranged. 6. Apparatus according to claim 1 or 2, characterized in that the device has two detector electrodes (32, 34), in the form of electrically conductive plates on an electrically insulating wall (14 "·) of the washing chamber one Washing machine (Fig. 4) are mounted. 709829/101 7