DE1797081A1 - Ultrasonic cleaning device - Google Patents

Description

PATENT Attorney DIPL.-ING. W. WEINKAUFF 1797081

FRANKFURT A. M. ■

Puke 71

Olevite Corporation in Cleveland, Ohio, U.S.A.

ULTRASONIC CLEANING DEVICE

The object of the invention is to provide a robust, inexpensive, gentle and thorough cleaning device indicate, with a vat for the cleaning liquid (liquor) and the objects to be treated in it.

The invention consists primarily in the fact that a piezoelectric vibrator on the underside of the tub bottom is fixed, fed from a transistor feedback latch.

Preferably, the stainless steel tub sits in an open-topped, cylindrical, upright bleohgehäuee, wherein the opening edges concentric and flush with each other from

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The vat and the housing are connected by a stretching thong B-ring made of elastic, electrically insulating & em Serfasrial. The piezoelectric vibrator is high zweafcssäßlg eeteeifeenfßrmig and ceramic dielektriseher Süt * Tuad sm Bo & s of the tub with the interposition of a "l" ktxieeh insulating tfiberglaematte fixed "As a result, he & sine Wechselspannungeaneohluß applied directly to the Tibrator _leg} without the Sefaar an electrical for the operator Sohlages consists · The fastening of the sea vibrator is expediently carried out as an adhesive connection made of epoxy resin with a low dielectric loss factor, with which the jiber glass mat is impregnated.

The Bleshgeh & ue is used for vibration-damping installation. Equipped with two rubber feet «Advantageously a hatchet © his cloak stamped and bent inwards as smsoles and at the same time as cooling surfaces for the outside.

The invention may be explained further the figures sohematically represented A », sftOaraiigsteelBpiele | i,

Show it: ' .

Figo 1 shows a circuit diagram of the! Dranaiet03? - ^ 0 @ Eilla ± «ffis Excitation of the piezoelectric vibrator,

2 shows an axial direction through the cleaning device,

! ig »3 a diagram of the impedance at vibrato, in keit vom! lüssigkeitsni / lveam ia

Fig. 4 is a view of the vibrator et al. Its 109827/0608

Pig. 5 shows the Sehaltschema a modified embodiment for the transistor oscillator, without Transformer,

6 shows a further circuit example for frequency modulation of the transistor oscillator.

As can be seen from Fig. 2, the cleaning device has a tub 11 which is suitably made of stainless steel and picks up the liquor with the objects to be cleaned by ultrasonic vibration. Preferably the tub is Resiliently attached In the exemplary embodiment, a housing 12 with feet 13 made of rubber-elastic material is provided for this purpose. The tub is flexibly suspended with its edge on the edge of the housing via the ring seal 15 made of silicone rubber. In the exemplary embodiment, the housing 12 consists of well heat-conducting BIeCh, preferably made of turned or drawn Aluminum.

The vibrator 18 is provided to generate the cleaning ultrasonic energy in the tub and its liquor 17. He consists of material of low dissipation factor to the ultrasonic energy to be able to generate, in particular, the adhesive material between the vibrator and the tub without disadvantageous heating. The piezoelectric vibrator is advantageously made of ceramic, namely a mixture of lead titanate and lead zirconate Üusiüzen as described in the United States patent 2 906 710, whereby the manufacturing process disclosed there is also advantageously adopted.

For example, a disk can be used containing a solid solution of lead zirconate, lead titanate and the

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mentioned additives. An alkaline earth metal * & «£ als3.sm Strontium is substituted for one Mb

Percent of lead »The molar ratio of B1« A weal I

Alkaline earth zirconate to lead and Srdal ^ mliiiitanat ± 33. l «r. . j

solid solution lies in the range jswi-Bch «a -65 * '35 vssA , j

45: 55ο An even lower loss factor in this material can be achieved -HiTech Uwelfcbmm substitutes, like besofariebeii in the USA-3fet * 9i4 5 068 177- ·

Preferably the vibrator 18 is BcheibexiXOxüBi & f: aacial

polarized and operated on the xaflialem BesooDteasdtee- \

quenze The vat 11 has a level edge, below which

the disk-shaped vibrator 18 is attached "ira" How wxtß I

1, the tub 11 is powerful, and the vibrator IB sits under its flat bottom 19, the diameter of which speaks roughly to that of the flat bottom 19. An ICLebTerbinua made of material with a low loss factor is provided between these parts in order to avoid harmful heating of the adhesive joint EU. This is preferably carried out with as it is under the trade name ^ir lCCO loni ⁵ " φ £ 45 ^; and cured one part catalyst Φ £ 15 and two parts" ECCO Bond " φ £ 45. Me can also consist of" Shell Ipon ^w €. »

TJm the operator when touching a Bottiohe genes. to protect against electric shock if a ϊοΐ flea? Alternating voltage source is on the vibrator, is the 18 isolated from the bottom 19 of the vat 11 on the? oh t a GIaBfasergewebes 21 which elne "wide under the tub bottom 19 and the other hand on AEEN vibrator 18, the epoxy resin of low loss factor or Bönetlge"

101527 / QfDi

Adhesive material attached iot. Fiberglass fabric can be used as it is used for the repair of car bodies, in a thickness of for example 0.3 mm.

In order to achieve good adhesion, the tub 11 is first cleaned with a solvent and roughened with emery cloth. After that, while the epoxy resin hardens, the vibrator is pressed against the bottom of the tub for about 12 hours, for example by placing a weight on it.

The piezoelectric disc-shaped vibrator 18 has generally silver-plated electrode surfaces, as in Pig. 4th shown ,,

The electrical connections are made via contact strips 22 on the upper silver-plated electrode 23, which is the Glued connection is facing. The tub 11 can be made of stainless steel and have an inside diameter of 9 cm, a depth of 6 cm, a disk-shaped piezoelectric vibrator 23 mm in diameter and 6mm thick, glued under the vat bottom, with a 0.05 mine strong silver electrode, on it contact strips, offset by 120 ° against each other. Preferably the contact strips are 22 soldered to the silver electrode 23.

The tub advantageously has rounded edges, especially at the transition between wall and floor, around the vibrator. The radius of the rounding is expediently between six and twelve millimeters, if possible not less than 0.6 mm. At a 6 cm-Bottioh, the rounding radius is 10 $ of the depth of the tub.

109827/0608 ^/

The surprising improvement in cleaning success through This rounding can probably be explained by the fact that more ultrasonic energy is then applied to the side walls of the Vat is transferred, whereby a more even distribution of the bottom performance is achieved »

An improved cleaning success is achieved with relatively low frequency, preferably close to the limit of audibility. Ea used to be difficult with such lower Operating frequency of the disc vibrator in Uckenschwingüng; to work. This required a disproportionately thick vibrator disk or an additional passive load mass on the disc, to reduce the resonance frequency «One thin disk of large diameter saves accordingly on piezoelectric material, because the operating frequency of Diameter is determined.

Its enlargement also enables a correspondingly greater power transmission.

For this purpose, if desired, the diameter of the vibrator disk can even be larger than that of the flat bottom part on the Tank"

To increase the mechanical reliability of the contact, lead wires 24 are on all three contact strips present, and these connections are embedded in the epoxy resin, as shown at 25, so that the strips can be underneath the ultrasound stress cannot wear out. As a counter electrode is a flexible wire 27 on the lower outer electrode 28 of the vibrator 18 is soldered.

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The oscillator circuit diagram according to FIG. 1 shows a relaxation generator for feeding the vibrator feed lines 24, 27 with a low frequency sound. A pair of series-connected transistors 31, 32 are provided. These sit on consoles 33, 34, which are in the Shell of the housing 12 are stamped and bent inward. Since the housing is made of a material that conducts heat well, such as sheet aluminum, the consoles 33, 34 act at the same time as cooling wings for the transistors 31, 32 attached to them,

In the embodiment of Fig. 1, an alternating voltage

ef f
source of 115 volts V provided. One hundred to one hundred and fifty volts are then on the charging capacitor 66 behind the rectifier 38

QJh
GleichspannunglraiB * _e The AC voltage source is indicated by the power plug 35 which may be equipped with a grounding contact 40 in addition to the WechselspannungGanschlüssen 36.37. The transistors 31, 32 are located between the latter in series with the rectifier 38. IIPN transistor interferers are preferably used. The transistor 31 has a collector 39, an emitter 41 and a base 42 o Accordingly, the transistor 32 has a collector 43, an emitter 44 and a base 45.

These transistors need a positive one to excite vibrations Base potential. This results from the voltage drop mm den Base series resistors 51, 52, each of which has a line 49 a ~. Rectifier 39 is connected, on the other hand each to one Base 42 or 45. The charging current of capacitor 53 between AC voltage terminal 36 and base 45 of transistor 32 is the start impulse for the vibration start.

The application of the transistor bases 42, 45 takes place via a transformer 54, which has a primary winding 55, in series with the

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j ;. - β - fe

piezoelectric vibrator 18 switched, and a pair of Secondary windings 56, 57 · As can be seen from the solenoid diagram, the current is stepped down in them. The secondary winding 56 lies between base 42 and the emitter core Traneistor 31 · The secondary winding 57 is connected between the base 45 and the emitter circuit of the transistor 32. The points in the illustration of the transformer 54 denote in-phase winding connections with one another.

Emitter resistors 46 and 47 are in series each. with the associated emitter 41 or 44. The secondary windings 56,57 are in a circuit from the base resistors 58, 59 and are bridged by eBSxönaensatoren 61, 62 to the waveform to improve the ultrasonic signal. The polarities of the secondary windings 56, 57 are in phase opposition at the associated transistor bases. As a result, the transistors 31,32 alternately conductive.

The protective contact 40 is connected to the aluminum housing 12 for safety reasons,

The device works at an operating frequency of around 43 kHz. Here, the transformer 54 may be somewhat ieiehtei ¹ and less expensive to construct than transformers in a main station. For the excitement only a small win & ungtzahl is needed. In the embodiment according to fig. 1, the current reduction ratio is two-fold 1t10, the primary winding 55 consists of a single turn, and each of the two secondary windings 56,57 consists of similar turns.

The transistors 31, 32 bind electrically isolated from the associated consoles 33 and 34, but in a well-thermally conductive " Connection with these. This can be achieved by interposing mica disks 63, covered with silicone paste.

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ORlSlNAi. INSPECTEp

The preferred level of cleaning liquid in the tub 11

is through the lines 64 and 65 in Pig. 2 specified »

j Water is generally used as the cleaning fluid.

[Since the required for generating cavitation · "for the cleaning effect in the water TJltraschallenergie decreases with increasing water temperature, it is desirable to use lukewarm water in the tub. 11 A wetting agent should be added _e The detergents customary for household cleaning can be used, such as the preparations known under the trade names "Joy ^w ," Liquid Lux "or the like. A few drops are sufficient, which should be stirred in the washing liquid before the device is switched on. The cavitation effect in the water is improved when excess dissolved (Jasmine) is pearled out. This is done by operating the device within a few minutes.

Since the piezoelectric vibrator 18 is firmly coupled to the tub and via this to the water filling, the The level of the water filling in the vat has an influence the energy transfer and resonance frequency of the vibrator 18. The dependence of the vibrator impedance on the water level is represented by diagram 67 in Pig. 3. Under the assumptions assumed there, there are minimum impedance values at water depths of 18 and 36 mm. The impedances are as the ordinate plotted against the water depth as the abscissa.

The cleaning device should be operated on one of the two operating points for minimum impedance. For example, suitable iioh d-er. Working point for 18 mm water depth, whichever is the best Cavitation effect results, for the inclination of dentures,

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ORIGINAL INSPECTED

r / s / 081

Shaving heads for razors, jewels, tips, spark plugs, small Werkaeugem m «ä * for 36 mm water depth (or height) iat catalepth. ftr.,. Äcillem, Silver device (which can only be found on a tmf tsns on the outer Btt & e clean), kitchen utensils, etc.

For most cleaning processes, all additional Oetergeniium is checked. However, it must be remembered iml the ült2Ma® © iim! Ll ~ cleaning a scrubbing process is _for why the addition wünsöfeeaswert a solvent for a particular acquired or to be detached Sohmutz smtti kanft.

The invention could also be put into practice «door se arrangement ¹ of vats connected to one another via Js -a-n Tikeator -t · If two vats are connected, each influences the Abetimmuaag and one vat could be used for cleaning τηκ & βΒ * - others for rinsing.

The oscillator could expediently be assembled from the following commercially available parts:

Transistors 31 and 32 - Belco OTS-410 rectifier 38 - RGA silicon slide tube 11-5194 smoothing capacitor 66 - Sprague for? A-1414 50 m?, 150 V starting capacitor 53 - 100OpT acceleration capacitors 61 and 62 - Sprague 2249-11-75

0.25 ff

Transformer 54 - Toroid-Indiaaaa Seatral € 51 108, ..

CompilationHBg -H "'■' ■ '

Base resistors 58 and 59 - 30 Uta », 1/4 W. Emitter resistors 47 - 1 0hm, 1/4 W. Emitter resistor 46 - j5 0hm, 1/4 t · '. ' _t ''

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Series resistor 51-47 Ohm, 1 W.
Series resistor 52 - 50 Ohm, 4 W.

Piezoelectric vibrator 18 - 52 mm in diameter, 6 mm

thick.

The two series resistors 51, 52 are of different sizes, corresponding to the associated emitter resistors 46, 47 o

Manufacturing effort and weight of the transformer can be avoided by using a different feedback circuit, as shown in FIG. This ironless oscillator includes complementary transistors 71 and 72; H. from the PNP type, the other is NPN type in the exemplary embodiment 71 the former and 72 the latter type. As a result, the bases 42 and 45 of the Series transistors 71 and 72 driven in phase opposition r / ground, so that these transistors conduct alternately.

The phase change in the feedback line 74 to achieve positive feedback while avoiding a transformer can also take place via a phase reversing transistor, which is also located between the DC voltage lines 49 and 37. It is of the NPN type, having a collector 76 to the positive line 49 and the emitter 77 to the negative line 37, in series with the series resistors 78 bsw · 79 · The ümkehrtransistor 75 has a BSIs 81, coupled via the capacitor 82 to the feedback line 74.

In conjunction with a rounding of the edges of the tub, a Even more even distribution of the ultrasonic energy is achieved by ire ^ uence modulation. This is according to the invention redht simply realized by utilizing the fact that the piezoelectric vibrators have different resonance frequencies have under different electrical conditions. When the vibrator alternates curvy clilooning and bridging

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If there is an impedance, it controls the oscillator alternately on or close to the resonance frequency and a slightly different frequency. In the embodiment B example According to FIG. 6, the impedance that becomes effective in the shunt to the vibrator is different, depending on whether the power rectifier 38 is currently conducting or blocking.

Let us first consider a small time interval during whose power rectifier is conductive to the charging capacitor 66. During this time interval, the feedback line 87 is connected to the other terminal of the charging capacitor 66, and vibrator 18 is connected through a low impedance circuit formed by Vibrator via the primary winding 551 the feedback line device 87, the straight line power rectifier 38, then alternately the charging capacitor 66 and transistor 32, and via transistor 31 (alternating at the rate of the oscillator frequency), then back to the vibrator through capacitor 61 shunted to base resistor 58. The charging capacitor 66 has low impedance for the oscillator frequency, Therefore it makes little difference, oo transistor 32 Conductive by increasing the vibrator current across the Charging capacitor 66, or whether the transistor 31 becomes conductive by bridging with the charging capacitor 66.

Now we have a time interval from the blocking phase dee Netzgleichriohters 38. Now the vibrator loop goes duroh the transformer primary winding 55 »feedback line 87, secondary base capacitor 86 (which bridges the power line), Line 88, transistor 32, charging capacitor 66, transistor (alternating with the oscillator frequency ”), capacitor 61 with shunt resistor 58, back to vibrator 18.

The shunt capacitor 86 may have the same capacitance the static capacity of the vibrator, or even less

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'■ Even good operating results have been achieved! if

• omitted the shunt capacitor 86 entirely. During the blocking '· phase of the mains rectifier is connected in shunt to the vibrator) 18, the high-frequency impedance of the Wechselatromnetzes, bridged by Neben3Chlußkondensator 86> and during the conductive

In the phase of the mains rectifier, the impedance of the capacitor \ 86 is practically ineffective. This "alternating" off and on; switch the impedance of the feeding Weohselatromnetaee nebet

• Shunt capacitor 86 as a function of the phase of the Mains rectifier causes a frequency modulation of the oscillator, whose stroke is equal to the mains frequency.

The connection of the vibrator with the feeding Weohselstrom-I, network via the feedback line 37 allows a current of j> Hetz frequency to flow into the base of the Iie ^ uftetore 31, whereby the Schwingungseinsat ζ is supported, instead of de.s in the> - Leadership example according to Pig »1 start capacitor 53 provided for this purpose.

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Claims (1)

-H- Expectations." 1.) Cleaning device, with a tub for the cleaning liquid (Fleet) and the objects in it in .fcehanäelhäe, marked daduroh, & a8 on the bottom ' dee Bottioh-Bodens (19) a piezoel ^ ttiifeojier vibrator (18) feat is, as a burden wid ^ rsiaia, Feedback circuit. 2p) cleaning device according to claim 1, dattttroh that the Bottioh (11) at its edge (H) with the band (16) a surrounding housing (12) is connected via a Sealing ring 13 made of rubber elastic, electrically insulating Material,; ^: '" ^: ■ ■ · ■■'". ' . · ■ '■ "' ■ ^l '■ —- · ^; ':". - \\ '.κ-, "■■■" ■ t * 3 ·) CleaningBgeräij according to AöBprueh 2, 9 & A ^ «&. geÄen ».aslohnet * da» the öehätup * (12> from gut-- WftmifeinnMfllH & te «hl and below the vat contains CUJ; lit · ', the lieieteratjrahBistoitsCL | 31 * 52} w and electrically insulating on ^. j» one. Io3ftßoie (are, hereuageaohlagen ^ ua Giern Mai ^^ l 4 ^ e CJahöueeß (12) and after innnej? Geigen *. ' _V '_; -Λ. - ■ !, ', ■ 4.) Cleaning device, daduroh marked that $ he uses the vibrator supporting bottom part (19) of the tank (11) above and Vibrator (18) is disc-shaped. 5.) Cleaning device according to claim 4 »thereby gekennaeichnet, that the vibrator (13) has an electrically insulating intermediate layer (24) made of glass fiber fabric under the bottom of the tub (19) glued 1st. 109827/0608 17971) 81 6o) cleaning device according to claim 5, characterized by an adhesive layer made of epoxy resin. 7.) Cleaning device according to one or more of the preceding Claims, characterized by calibration lines (64,65) im Vat (11) corresponding to the liquid vean which is assigned to the minimum tverts of the vibrator impedance. 8.) Cleaning device according to one or more of the preceding Claims, characterized in that the piezoelectric body of the vibrator (18) consists of a solid solution of lead zirconate, lead titanate and at least one alkaline earth metal from the group consisting of potassium and strontium for one to thirty atomic percent of the lead in the zirconate and Titanate, the molar ratio of lead and alkaline earth zirconate to lead and alkaline earth titanate in the solid solution is in the range of 65:35 to 45:55. 9 ·) Cleaning device according to one or more of the preceding claims, characterized in that the edges of the tub (11) are rounded around the area of the vibrator (18), with a radius of preferably 10 ff * the tub depth. 10.) Cleaning device according to one or more of the preceding Claims, characterized in that its oscillator circuit has two power transistors connected in series (31,32 or 71,72), connected in push-pull to the vibrator (18). 11.) Cleaning device according to claim 10, characterized by a current-reducing feedback transformer (54) between the vibrator circle and the base circle of the two Power transistors, with oppositely polarized secondary windings (56.57) for each transistor. 12β) cleaning device according to claim 10, characterized by the use of a phase reversing transistor (75) in the Feedback path, where the power transistors (71,72) are complementary to each other. 13.) Cleaning device according to one or more of claims 10 to 13, characterized by a frequency modulation feedback line (87) between the voltage side of the mains rectifier (38) for the RC oscillator on the one hand and the load circuit with the vibrator (18) on the other handSo BATH 109827/0608 /