US3085416A - Device for the automatic adjustment of the composition of bath fluids in apparatus for the chemical cleaning of textile materials and similar matter - Google Patents

Description

April 16, 1963 DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPARATUS FOR THE CHEMICAL CLEANING Filed Jan. 10, 1961 OF TEXTILE MATERIALS AND SIMILAR MATTER 4 Sheets-Sheet 1 INVENTOR ATTORNEYS April 16, 1963 E. DH OG 3,085,416

DEvIcE FOR THE AUToMATIc ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPARATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS AND SIMILAR MATTER Filed Jan. 10, 1961 4 Sheets-Sheet 2 if 7 36 I 4 @2 6 L7 /4 a; if /z 1 7 w 25 .7 %4\ '49 5 Z a/ 22 2/ U Q Q n W U A; A

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ATTORNEYS Aprll 16, 1963 E. DHOOGE 3,085,416

DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPARATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS AND SIMILAR MATTER Filed Jan. 10, 1961 4 Sheets-Sheet 3 INVENTOR zmzze J/i aa z WEE MTE/ ATTORNEYS April 16, 1963 E. D'HOOGE DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPARATUS FOR THE CHEMICAL CLEANING Filed Jan. 10, 1961 OF TEXTILE MATERIALS AND SIMILAR MATTER 4 Sheets-Sheet 4 e: f7 l v l w I 2% Z J INVENTOR ATTORNEYS 3,085,416 DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPA- RATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS AND SIMILAR MATTER Emile DHooge, Ghent, Belgium, assignor to Ateliers de Construction Emile DHooge S.P.R.L., Ledeberg, Belgium Filed Jan. 10, 1961, Ser. No. 81,716 Claims priority, application Belgium July 15, 1960 9 Claims. (Cl. 68-13) The invention concerns a device for automatically adjusting the composition of the bath in apparatus used for the chemical cleaning of textile or similar matter, and in particular of clothing and underclothing.

As is generally known, the method of steaming or chemically cleaning clothing or similar matter consists of a treatment with a solvent of greasy substances, naphtha being frequently used, despite the fact that it is highly inflammable. It is much safer to use other organic solvents such as Tri (trichlorethylene), Perc or W.S., wherein soapsuds can be dissolved, in order to loosen dirt particles. The clothing is placed in the drum of the washing machine where it is mechanically rinsed in the cleaning fluid. During this method, the fluid of the bath is being continuously extracted in a closed circuit, to be pumped back into the processing chamber after having been passed through a cleaning filter.

it is most important to maintain a constant quality of cleaning, which must be independent of the relative humidity of the surrounding atmosphere as well as of the moisture content of the clothing at the moment it is introduced into the machine. In order to obtain these conditions, it will be necessary to bring the composition of the processing bath, and most particularly its water and soap content, to a predetermined value which will be dependent upon the nature of the fabrics being treated, and to maintain this value within narrow limits.

This value is different for the various varieties of fabrics. 'It is generally accepted, that loosely woven or knitted woolen fabrics as well as silk, may be processed at a value of relative humidity no higher than 65%. Carded wool, such as mens clothing, can bear up to 78% and pure cotton, such as rain clothes for instance, can stand up to 85 or 87% of relative humidity. Should these values be exceeded, the materials will first start to crease, and next to shrink, to turn feltish, etc. If the cleaning is to be carried outwith maximum efficiency so as to obtain optimum results and to have the lowest possible need for subsequent spot removal, it will be essential to maintain with accuracy the relative humidity which has been determined for the processing of the material being treated.

In the machines and installations used up till now, the desired relative humidity is obtained by the addition of water to the cleaning fluid during the cleaning method; this is however only possible when the solvent has been mixed beforehand with a predetermined amount of soap, suflicient to absorb the required quantity of water. In consequence, this procedure can only be applied in practice to machines which operate with a permanent and constant concentration of soap, i.e. according to the charged system.

The required quantities of water are introduced in the circuit at a point preceding the pump, the water supply being regulated by an electrically controlled valve in accordance with the instantaneous measurement of prevailing humidity. The water thus passes through the filter, where the filtering powder will be unnecessarily moistened. In all known systems, the measurement of the humidity is carried out by means of an electrolytic meas- 3,085,416 Patented Apr. 16, 1963 uring cell, the increased electric conductivity of which is used as a measure for the quantity of water to be added to the solution. This presumes, that the solvent, Perc for instance, has a considerably smaller specific conductivity than Water. This is not correct however consider ing that chemically purse water is also but a very poor electric conductor. In fact, what one measures is mainly the concentration of salts or other electrolytes which are dissolved in more or less constant proportions in the water. Such measurements are consequently most unprecise, as they may depend uponthe hardness of the Water being used, as well as upon the largely variable proportions of fatty acids and impurities which are present in the solution; they may also be influenced by the nature of the soap being used.

A further drawback of these measuring methods consists in the fact, that in practice it is not easily possible to bring the measuring instrument into contact with the liquid of the bath at a point where aforesaid liquid has is effective composition. At such a point the danger would exist of the electrodes of the measuring cell being shorted by textile fibres or impurities present in the liquid, thus rendering the instrument totally useless. It is for this reason that in practice the measuring cell is introduced at a point in the circuit past the filter. At such a point however, the composition of the liquid is no longer the same as that in the actual cleaning drum, which represents another cause of Wrong measurements. This is most apparent when moist clothing is introduced into the machine, the moisture being readily absorbed by the filter, which at that moment is still quite dry, so that the supply of water is adjusted without taking into account the moisture content of the introduced clothing. Such poor control can easily give rise to oversaturation and consequently to the known trouble due to this state of alfairs.

In order to obtain more trustworthy results for these measurements, propositions have already been made to replace the electrolytic measuring cell by some hygrometric device, not being in contact with the liquid itself, but merely with the vapour present above the liquid. For this purpose hair hygrometers are used, of which the moisture sensitive element (hair) is not influenced by the vapours of the solvents, but only by water vapour. When this element absorbs moisture, its length varies and these variations in length are transmitted to a pointer which moves along a graduated scale. This scale may be calibrated for instance from 0 to of relative humidity.

. Such a device can now be used to measure the true moisture content of the bath liquid and, according to the indications thereof, the quantity of pre-prepared soap and water solution (standard suds) which is introduced into the circuit can be adjusted.

t The manner in which these principles are being applied in the propositions known until now has shown many a failure in the practical application thereof, the device having been the cause of a considerable slow-down and (being insufficiently reliable in operation, so that it requires a constant supervision.

The object of the invention is to provide a new and greatly improved device which, by using a hygrometer for determining the moisture content of the bath fluid,

eliminates the above-mentioned drawbacks and assures an accurate control of that moisture content in all circumstances.

According to the invention, the device for automatically adjusting the composition of the bath in apparatus for the chemical cleaning of textile or similar materials, where the bath fluid is circulated in a closed circuit through a filter unit and where water and chemicals are added to this circulating fluid under control of a device for measuring relative humidity, is characterized by the fact that the measuring device is located in a separate control circuit which is independent of the filter unit and in which the cleaning liquid is tapped straight from the cleaning drum and fed into the measuring equipment, eventually through an individual filter, whilst the water and washing products which are added under the control of this device are poured straight back into the cleaning fluid.

In a particularly favourable form of embodiment according to the invention, the measuring circuit comprises a mixing device introduced into this circuit at a point past the measuring equipment, so that the bath fluid circulating in the measuring circuit can be mixed with a quantity of aqueous soap solution controlled by the measuring equipment before it is returned to the cleaning drum. Preferably but a small quantity of the fluid circulating in the control circuit is actually fed as sample to the measuring equipment, the remainder being led directly to the mixing device. In order to assure an intimate mixing, this mixing device has been built in the shape of a venturi, whereby the bath fluid coming straight from the cleaning drum passes through the venturi jet, sucking up the fluid returning from the measuring equipment as well as the controlled amounts of water and soap which are supplied through separate pipes. It is moreover an advantage when the supply of water and of cleaning products, generally soap, can be controlled separately and independently, so that it becomes possible to add soap without water, as required for instance when the clothing being introduced already contains sufficient moisture which must be absorbed by the added soap and combined with the solvent.

Preferably the measuring equipment shall consist of a cylindrical container, in the bottom part of which at least one inlet pipe and at least one outlet pipe are fitted, whilst the top part of the container is connected to a humidity measuring equipment which is influenced by the vapour of the bath fluid Without coming into actual contact with the fluid. This measuring equipment may consist of a hygrometer, a hair hygrometer for instance, the sensitive element of which is not influenced by the solvent vapours, but exclusively by water vapour. This hygrometer is equipped with an adjustable contact device, preferably fitted with an adjusting pointer, which can be set in such a manner as to close an electric contact as soon as a predetermined degree of relative humidity is reached, thus completing an electric circuit which operates the interruption of the water supply.

When certain materials such as cotton, which need a high relative humidity, have just been treated and it is required immediately afterwards to clean other materials such as light wool which can bear only a much lower degree of humidity, it is necessary to take into consideration, that the vapour pressure of the water in the measuring equipment remains at a high value during a considerable time, so that the pointer of the hygrometer will only recede very slowly. The new washing method may how ever not be started before the pointer of the hygrometer indicates a much lower value of relative humidity, as otherwise the water supply will not be properly controlled.

In order to speed-up this method, a third pipe is fitted to the cylindrical container of the measuring equipment, so as to enable a stream of dry air to be passed through the container after each washing method, thus driving away the remaining water vapour. The measuring instrument can then be provided with a second contact device, closing an electric contact as soon as the humidity indicated by the hygrometer drops below a pre-determined value, aforesaid contact controlling a circuit which shuts off the dry air supply. Immediately afterwards, fresh water for the new washing method may be supplied.

In order to be sure that the control of the water supply is correctly dependent upon the relative humidity in the bath, it is essential that .the measuring instrument effectively indicates the correct value. If for any reason, such as the clogging of the supply pipe for instance, the measuring instrument receives too small a quantity of bath fluid, or even none at all, this might result in a continuous additional supply of water. To prevent such an occurrence, a safety device is incorporated in the pipe which returns the fluid from the measuring equipment in such -a manner that the water supply can only operate as long as a pre-determined quantity of fiuid is being drained from the measuring equipment. Such a safety device could for instance consist of a small bowl or cup controlling a switching device by means of a lever, and into which cup flows the fluid leaving the measuring equipment. The weight of the fluid then tilts cup and lever, thus closing the contact device. A small hole is provided in the bottom of the cup, so that the fluid can drain away. As long however as a sufficient volume of fluid is evacuated from the measuring equipment, the cup will remain full and the contact closed. When on the other hand, the flow of fluid through the measuring equipment is restricted for some reason or other, the cup will empty itself, so that the lever will tilt over and break the contact.

For added safety, signalling lamps or other warning signals can be incorporated in the electric circuits, showing the positions of the various contacts and switches. For instance, a red flashing light could be installed which lights as long as the water supply is open, providing a permanent check upon the functioning of the hygrometer pointer.

These and further characteristics of this invention will be clarified by the following more detailed description, which is merely informative and in no way restrictive of the scope of the invention, and by the appended drawings in which:

FIGURES 1 and 2 give a schematic representation of the control and adjusting devices as used up till now;

FIGURE 3 represents a schematic view of the control device, applied according to the invention;

FIGURE 4 gives a general sketch of the control apparatus according to the invention, with indication of the principal elements comprised therein;

FIGURES represents a more detailed diagram of the control devices according to the invention;

FIGURE 6 is a large scale representation of the safety devices applied to the control apparatus;

FIGURE 7 is a more detailed view of the mixing device incorporated in the control apparatus;

FIGURE 8 is a simplified diagram of the electric control circuits.

In FIGURE 1, which schematically represents a frequently applied arrangement mainly suitable for the charged system, 1 is the processing chamber of the washing machine in which the laundry contained in drum 2 is being rotated. The bath fluid 3 contained in chamber 1 is continually being evacuated through outlet pipe 4 and thus arrives in collector pipe 5 from where it is pumped through filter element 7 by means of pump 6 to be returned into chamber .1 through mlet pipe 8. In order to be able to add the required quantity of water to the bath, water reservoir 9 is connected through an electrically controlled valve lib and pipe 11 to a point in the circuit preceding pump 6. Past filter element 7, an electrolytic measuring equipment has been introduced in the circuit, capable of deliveringa control potential dependent upon the conductivity of the fluid passing at that point. This control potential is then sufficiently amplified in an amplifying circuit represented schematically at 13 to control valve 10 in such a manner as to close it as soon as theconductivity measured by the electrolytic cell exceeds a predetermined value.-

Besides the drawbacks already mentioned in the introduction concerning the electrolytic method of measuring the degree of humidity, this system further possesses among others the following disadvantagesi as the water is introduced at a point preceding filter element 7, the latter as well as the filtering powder it contains are quite use lessly moistened. Even if we presume that the measuring equipment is capable of correctly determining the 'value of relative humidity, the generated control potential would be proportional, not to the relative humidity of the fluid contained in chamber 1, but rather to the relative humidity of the fluid returning to aforesaid chamber, which might have its composition considerably altered by the action of the filter. In fact, any increase in moisture content will only be detected past the filter element with considerable delay, so that it could easily happen that the water supply is maintained longer than it should be. 'Should it be required to wash materials requiring but little moisture, such as light woolen fabrics, immediately after having processed materials which can bear a considerable amount of moisture, the bath fluid having thus to be renewed, the dry solvent will absorb moisture from the filter element, so that in this case as well the results of the moisture measurements will be wrong. Finally, when working with the charged system, a constant predetermined soap concentration is present, which already makes it impossible to adjust the amount of soap used in correspondence with the optimum supply of water.

In FIGURE 2 a more recent proposition is represented schematically, all corresponding elements being indicated by the same reference numbers as in FIGURE 1. In this case as well, bath fluid 3 flows through outlet pipe 4, collector pipe 5, pump 6, filter element 7 and return pipe 8 in a closed circuit. Samples of the bath fluid are tapped off at a point preceding filter element 7 and are led through a simple filter 15 and a hand operated adjusting cock 16 to a cylindrical container 14, to be returned to the main circuit of the bath fluid through pipe 17. In the top of container 14 a measuring instrument is located, which under normal circumstances will be in contact merely with the vapours, but never with the fluid itself. The measuring instrument used is a hygrometer, and preferably a hair hygrometer.

As long as the degree of humidity remains below the required value, auxiliary pump 10 is operated, being stopped as soon as the relative humidity has reached the desired value. This auxiliary pump controls the supply of standard soap solution from reservoir 9 through pipe 11 to a point in the circuit between collector pipe and main pump 6. t t

This arrangement also has the disadvantage that the added water moistens the filter content, so that difficulties are encountered as soon aslight woolen materials have to be washed immediately after cotton fabrics.

In its practical form of embodiment however, this installation shows further important drawbacks: The bypass pipe towards the measuring equipment being relatively narrow in view of the volume of the samples to be tapped off, the hygrometer can but react with considerable delay to the modifications in moisture content of the bath fluid. Consequently, after the introduction of fresh bath fluid or after moist clothing has been placed into the machine, a considerable time elapses, approximately 8 minutes, before the hygrometer indicates the correct humidity. The supply of fluid to the measuring equipment is moreover dependent upon the pressure available at the inlet of filter element 7. Should this rise inconsiderately, the flow will become too great so that the sensitive element will be rendered inoperative by immersion. The system will be totally out of order as long as this condition prevails. To prevent such an occurrence, the feed must be adjusted manually by means of cock 16 at each new washing method.

Also, whenever auxiliary filter 15 gets clogged, standards suds will be continually added from reservoir 9'. From practical experience it has been found that this filter has to be cleaned several times a day. Moreover, the addition of water and soap in a fixed proportion is far less flexible, considering one is obliged to add water, even when soap alone is required. Finally, there is always a considerable delay between the end of one washing method and the beginning of the next, considering that the hygrometer as well as its cylindrical container must first be thoroughly dried before it is possible to obtain a trustworthy measurement of the new bath fluid. In practice this delay seems to last approximately 12 minutes, during which period no fresh water can be added. Due to all these circumstances, a complete. washing cycle will take about 20 minutes longer than the actual time required by the washing method proper.

By applying the dispositions according to the invention, which are schematically represented in FIGURE 3, all these inconveniences are systematically eliminated, as will be made clear by the following description. As in the known methods previously described, the measuring instrument in this case is also a hygrometer 12 connected to the top end of a cylindrical vapour chamber 14, which is thus capable of determining the relative humidity without being in contact with the liquid itself. This hygrometer is however placed in a circuit which is totally independent of main filter element 7, to which circuit water and soap can be added under control of the measuring equipment without being able to moisten filter element 7. The bath fluid flowing through outlet pipe 18 is pumped by pump 20, through steel wool filter 19 into pipe 21. The greater part of this fluid reaches mixing device 24 by means of pipe 22, whilst the remaining part reaches vapour chamber 14 through a much narrower pipe 23- and serves as sample for the measuring equipment, finally also flowing back into the aforementioned mixing device 24, through outlet pipe 25 and safety device 26. In this mixing device 24, the bath fluid is thoroughly mixed with the eventually added quantities of water and soap supplied from separate reservoirs 27 and 30' through pipes 29 and 32 respectively, before being poured back into the processing chamber through evacuation pipe 33. This addition of water and soap can be controlled automatically by means of electrically operated valves 28 and 31 provided respectively in pipes 29 and 32.

By a proper choice of the diameters of pipes 21 and 22 and of the power of auxiliary pump 20, a powerful and rapid circulation of the bath fluid can be obtained. The fluid is thus rapidly brought close to measuring instrument 12, so that the latter can react without delay to any modification of the composition thereof. This powerful stream of liquid is further used in mixing device 24 to obtain the intimate mixing of the (fluid with the added quantities of water and soap. The safety device 26 is arranged in such a manner as to operate, closing the water supply, as soon as the flow from pipe 25 coming from the measuring equipment ceases or becomes insutficient.

connected up in such a manner to the supply system of fresh bath fluid as to shut off this supply as soon as the level in processing chamber 1 has reached the required height P. The device can also be interconnected in such a manner with the control circuit as to automatically start pump 20 as soon as level P has been reached, after which the control circuit for the water supply can also be prepared. As is also shown schematically in this FIGURE 5, hygrometer 12 is provided with three pointers 35, 3'6 and 37 which can be displaced along a graduated scale which has not been drawn. Among these, pointer 35 is the one which is connected to the sensitive element, usually a hair, 38, in such a manner that it indicates the instantaneous value of water vapour content in vapour container 14. Pointers 36 and 37 can be displaced manually along the dial graduations, pointer 36 being adjusted to the desired minimum value of relative humidity and pointer 37 to the desired maximum value. These pointers :are fitted respectively with contacts 36' and $7, which cooperate in such a manner with mobile indicator pointer 35 (see FIGURE 8), that when this indicator pointer coincides with the lower adjusted value, a contact is closed across the secondary winding of a transformer 40, and that when aforesaid indicator pointer coincides with the upper adjusted value, a contact is closed across the secondary winding of a second transfonmer 4-1.

Besides the two previously mentioned pipes 23 and 25, yet a third pipe 42 opens up into vapour chamber 14', leading from a dry air supply and being fitted with an electrically operated control valve 43. This air pipe is opened up at the end of each washing method, thus supplying a stream of dry air which thoroughly dries out the inside of vapour chamber 14 and hygrometer 12. The arrangements are such, that the hygrometer will control valve 43, more particularly by the action of indicator pointer 35 closing the contact elements 36 provided on adjusting pointer 36, in such a manner that this valve will close and shut off the air supply to pipe 42, as soon as the measured relative humidity corresponds to the lower adjusted value.

In this case, pipes 22 and 23 are provided respectively with adjusting cocks 39 and 39' in order to be able to adjust the flow through the corresponding pipes.

Safety device 26 provided in pipe 25 between the measuring equipment and mixing device 24 is represented separately and on a larger scale in FIGURE 6. It mainly consists of a cylindrical container with funnel shaped bottom which leads into outlet pipe 49 returning to mixing device 24. In this container, a cup 44 is located under outlet opening of pipe 25 and fixed to the end of a lever 45, the latter being free to pivot about fixed pin 46. The other end of this lever is provided with a mercury switch represented symbolically in the drawing by mercury tube 47. This mercury switch comprises two independent contacts, shown as 50 and 51 in FIGURE 8, which close when the cup tilts down under the weight of the contained fi-uid. When however this cup is empty, or almost empty, the lever will be tipped to the horizontal position by the weight of the mercury tube and eventually of added counter-weights, thus opening the contact. As to the mention of added counter-weights is meant that the lever includes counter-weights in addition to the mercury tube in case the weight of this mercury tube is not sufficient to hold the lever in its horizontal position when the cup is empty. An evacuation hole 48 is provided in the bottom of cup 44, the flow through this opening being chosen in such a manner, that as long as a sufficient flow of liquid from the measuring equipment reaches cup 44 from pipe 25, the level of liquid will rise in the cup and overflow the edge thereof into container as, the cup thus remaining in its tilted down position. Should however the flow from pipe 25 cease, the liquid in the cup will drain away through opening 48, so that the lever will tilt back to the horizontal position, thereby opening the mercury switch.

The mixing device 24 incorporated according to the invention in the adjusting circuit is shown on a larger scale in FIGURE 7. This mainly consists of a cylindrical closed container 52, to the bottom of which a funnel shaped part 53 is fitted, the latter being connected to outlet pipe 33' which leads back to processing chamber 1. Pipe 22 leading straight from auxiliary pump 29 is terminated by a jet nozzle 54 placed close to and concentrically with funnel shaped part 53 of the container bottom. Three pipes 29, 32 and 4-9 open up in the top of cylindrical container 52, the first of which leads via control valve 28 from water reservoir 27, the second being connected via control valve 31 to the soap reservoir 36, whilst pipe 49 is the one returning the sample of bath fluid from the measuring equipment, through safety device 26, to the mixture. This mixture is next powerfully, sucked up by the venturi action of jet nozzle 54, by means of which the thorough mixing of the soap solution with the bath fluid is obtained.

The operation of this complete equipment can now be explained with reference to the wiring diagram of FIG- URE 8. L and L now represent the power leads which feed the control system through fuses Z.

At the beginning of a washing method, the necessary quantity of solvent is introduced into the processing chamber and simultaneously, before the required level is obtained in aforesaid processing chamber, pump 20 is started, thus pumping a continuous stream of fluid through the control circuit 21-22--2333. By means of float device 34, the supply of solvent is stopped, by a procedure which needs no further explanation, as soon as the desired level P is reached in the washing chamber. A small portion of the fluid thus set in motion reaches the measuring equipment through the by-pass pipe and then fiows through pipe 25 intothe safety device, where it is collected in cup 44, which at the time is still in horizontal position. Considering that normally more fluid is supplied through pipe 25 than can be evacuated through the narrow opening 48, the level of fluid will rise in the cup, until the latter is tilted down by the weight of the fluid accumulated therein, thus closing contacts 50 and 51. The overflowing fluid then returns through pipe 4-9 and mixing device 24 into the circuit.

In this manner the measuring equipment is continually fed with a certain quantity of bath fluid and is consequently capable of indicating the correct moisture content of the bath. At the same time, the closing of the mercury switch has prepared the control circuit for the addition of water, which condition is signalled by the lighting of a green pilot lamp 56.

When the clothing which is to be cleaned comes into contact with the solvent, three cases are possible:

(1) The clothing contains the same degree of moisture as the solvent and no modification of the degree of hu-' midity occurs, so that the hygrometer pointer does not move; I

(2) The clothing is less moist than the bath fluid and absorbs moisture from the bath, so that the hygrometer pointer will recede;

(3) The clothing contains more moisture than the bath fluid and gives off some of it to the bath, so that the hygrometer pointer advances.

The time required to obtain equilibrium between the degree of humidity of the clothing and that of the bath is of the greatest importance. Theoretically one should wait till the hygrometer pointer is at a standstill, before proceeding with the eventual addition of water. In favourable circumstances this will last at least one minute. In practice, with automatic machines, the addition of water is made dependent on the reaching of the desired level in the processing bath, i.e. that no water can be added before the required quantity of solvent is available.

The washing bath thus consists of a fixed quantity of solvent which is introduced into the drum and of which a sample is sent to the hygrometer equipment during at least one minute.

After this adjusting period, Water can be added if required, i.e. if at that moment the indicator pointer 35 of hygrometer 12 has not yet reached adjusting pointer 37.

In a manner which need not be described here, power is applied to terminals 57 and 57-see FIGURE 8the first of which is directly connected to the feed of control valve 31 and also via closed mercury contact 50 and closed relay contact 60 to the feed control valve 28. Consequently both control valves 31 and 28 are opened, so that soap as Well as water is supplied to the mixing device 24, which means that these products are fed into the bath fluid in the form of an emulsion, having been thoroughly mixed. The opening of the water supply is made known by the lighting up of a red pilot lamp 62.

By applying power to terminal 58, current will also flow through relay winding R3, connected in series with the primary winding of transformer 41. Due however to the high impedance of this transformer, the value of the current is kept so low, that the relay can not operate. This is the case as long as indicator pointer 35 of hygrometer 12 has not yet reached the position of adjusting pointer 37. By the addition of water however, the indicator pointer will start to rise until it finally touches contact 37' of adjusting pointer 37. This then shortcircuits the secondary winding of transformer 41, so that the impedance in series with relay R3 is reduced to a very low value, thus energizing the relay. The relay then operates, opening the energizing circuit of water control valve 28 at point 60. The soap supply still remains open, as long as terminal 57 is under power. If right from the start the bath contained sufiicient water, so that pointer 35 of the hygrometer had already reached the required position, the relay would have prevented the energization of the Water supply system, also right from the start, so that the application of power to terminals 57 and 58 would have opened the soap supply exclusively.

In this manner the desired relative humidity, set by means of pointer 37, can be obtained in each case, after which the washing method can be continued under optimum conditions. It is advisable to apply a washing period of approximately 8 minutes, in order to assure perfect results.

The washing method is followed by rinsing, preceded or not by drainage of the bath fluid. As soon as the predetermined washing time has elapsed, power Will be cut oft" from terminal 58, thus stopping pump motor 55 which is connected to it. Simultaneously power is applied to terminal 59, thus energizing air supply control valve 43 via closed relay contact 61. A current also flows through relay coil R4; due however to the high impedance of the primary winding of transformer 40 which is connected in series with a aforesaid coil, this current is so weak, that the relay can not operate. By the introduction of dry air via pipe 42 and control valve 43 into the measuring equipment 12, the latter is being dried, so that indicator pointer 35 starts receding and finally touches contact 36 of adjuster pointer 36. The secondary winding of transformer 40 is thereby short-circuited, reducing the impedance in series with relay winding R4 to such a low value that it can no longer prevent the relay from operating. This opens the energizing circuit of the air supply system at 61. The hygrometer is thus automatically prepared in the correct manner for a following washing method.

The green and red pilot lamps, respectively 56 and 62, can be used as safety devices for the correct operation of the apparatus. Green pilot lamp 56 lights as long "as the mercury switch is closed. This is normal as long as pump 20 is in operation, producing a constant flow of fluid reaching safety device 26 via measuring equipment 12. Should this pilot lamp however remain lighted several minutes after the pump has stopped, this would indicate that evacuation opening 48 of cup 44 is clogged, preventing the draining away of the liquid.

The red pilot lamp lights as long as the water supply is opened. Should this however last an abnormally long time, i.e. when pointer 35 has already reached contact 37' and the water supply nevertheless remains open, this water supply will immediately have to be shut off by means of a manual cock (not shown).

It will be quite clear, that the above detailed description only relates to one particular form of the many possible forms of embodiment of this equipment according to the invention. Remaining within the scope of the invention, it is obvious that either the detailed construction of the various elements or the manner in which these elements work together can be modified in various ways, as long as the principles laid down in the claims below 10 are maintained. The invention covers all these possible alternatives.

What I claim is:

1. Dry cleaning apparatus in which the goods to be cleaned are washed and a dry cleaning solvent composi-. tion is circulated in a closed circulation path, comprising a rotatable washing drum, a filter and a pump in pipe communication with each other and to the drum, a humidity measuring device having an inlet and an outlet, a by-pass pipe interconnecting an outlet of said pump and said inlet of said humidity measuring device to divert a small stream of circulating solvent composition to said humidity measuring device, a reservoir for water, a reservoir for washing materials, each of said reservoirs having an outlet, control means responsive to said humidity measuring device to regulate the flow of said Water and of said washing materials to said circulating solvent composition, a mixing device for mixing said water, said washing materials and said circulating solvent composition, said mixing device including a container provided with one outlet and four inlets which are connected to the outlet of said first-mentioned reservoir, the outlet of said second-mentioned reservoir, the outlet of said measuring device and the outlet of said pump respectively, and the outlet of said mixing device being connected to said wash-ing drum.

2. Dry cleaning apparatus according to claim 1, in which two electrically operated valves are provided with the outlets of said first and second reservoirs being connected to said mixing device by the first and secondmentioned electrically operated valves respectively, said valves being each individually controlled.

3. Dry cleaning apparatus according to claim 1, in which the said container is formed as a cylindrical body fitted with an evacuation funnel in its bottom, said first, second and third-mentioned inlets terminating in the top of said cylinderical body, with the fourth-mentioned inlet extending lengthwise through said cylindrical body and terminating close to the opening of the funnel, and in which a jet pipe nozzle is provided mounted in said opening of the funnel.

4. Dry cleaning apparatus according to claim 1, in which a hygrometer is provided connected to said humidity measuring device and which is uninfluenced by the vapours of said solvent composition but reacts only to the water vapours mixed therewith.

5. Dry cleaning apparatus according to claim 1, in which an electrically operated valve is provided, the said measuring device being mounted in a cylindrical container fitted with a supply pipe which is coupled with a source of dry air by means of the electrically operated valve.

6. Dry cleaning apparatus according to claim 1, in which the said humidity measuring device is provided with a hygrometer which is uninfluenced by the vapours of said solvent composition but reacts only to the water vapours mixed therewith, and in which an adjustable contact device is provided for the hygrometer and which closes an electric contact as soon as the measured humidity reaches a predetermined value, and another contact device closes a second electric contact as soon as the measured humidity drops below a predetermined value.

7. Dry cleaning apparatus according to claim 1, in which the said humidity measuring device is provided with a hygrometer which is not influenced by the vapours of said solvent composition but reaches only tothe water vapours mixed therewith, and in which said hygrometer is fitted with an indicator pointer moving along a graduated scale, and a further pointer is provided manually adjustable along said scale, said pointers having control parts of an electric contact device which is closed as soon as the relative humidity indicated by said indicator pointer reaches the value determined by said adjustable pointer.

8. Dry clean-ing apparatus according to claim 1, in which the said humidity measuring device is provided with a hygrometer which is uninfluenced by the vapours of said solvent composition but reacts only to the water vapours mixed therewith, and in which-the said measuring device is mounted in a cylindrical container fitted with a supply pipe which is coupled with a source of dry air by means of "an electrically operated value, and a contact device closes an electric contact as soon as the measured humidity drops below a predetermined value, in which control means are provided including first and second electric contacts and first, second and third electrically operated valves, and said first-mentioned electric contact being coupled with said first-mentioned electrically toperated valve, whereas the second-mentioned electric contact is coupled with said third-mentioned electrically operated valve so that when said first-mentioned electric contact is closed and first-mentioned valve is operated thus shutting off the air supply, and in which the control means includes a safety device incorporated in the pipe connecting said outlet of said humidity measurting device and said third-mentioned inlet of said mixing device, the safety device controlling a third contact device which is coupled with said first-mentioned electric contact and said first-mentioned electrically operated valve so that the water supply can only be opened when and as long as a predetermined minimum quantity of solvent composition flows from said humidity measuring device.

9. Dry cleaning apparatus according to claim 1, in which the said humidity measuring device is provided With a hygrometer which is not influenced by the vapours of said solvent composition but reacts only to the water vapours mixed therewith, and in which the said measuring device is mounted in acy-lindrical container fitted with a supply pipe which is coupled with a source of dry air by means of an electrically operated valve, and a contact device closes an electricrcontact as soon as the measured humidity drops below a predetermined value, and in which a second contact device is provided constituted by a mercury switch which is operated by a pivoting lever capable of turning between two extreme positions determined by stops, and to one end of which a small fluid cup is attached, the latter tending by means of its weight and the fluid therein to move the lever towards one of its extreme positions at which the switch is closed, a counterweight return device pulling the lever towards its other extreme position at which the contact is open so that as long as the cup contains a predetermined quantity of liquid, the switch will be maintained closed by the weight of the cup and the predetermined quantity of liquid, whereas the switch will be opened, closing the water supply, whrenever the quantity of liquid in the cup drops below said predetermined value, the tilting fluid cup being fitted inside a container provided with an outlet pipe leading to the mixing device, the outlet of the measuring device ending; in the said last-mentioned container just above the cup.

References Cited in the file of this patent UNITED STATES PATENTS 2,913,893 Mathews et a1. Nov. 24, 1959 2,940,287 Henderson June 14, 1960 2,967,084 Reitz Jan. 3, 1961

Claims (1)

1. DRY CLEANING APPARATUS IN WHICH THE GOODS TO BE CLEANED ARE WASHED AND A DRY CLEANING SOLVENT COMPOSITION IS CIRCULATED IN A CLOSED CIRCULATION PATH, COMPRISING A ROTATABLE WASHING DRUM, A FILTER AND A PUMP IN PIPE COMMUNICATION WITH EACH OTHER AND TO THE DRUM, A HUMIDITY MEASURING DEVICE HAVING AN INLET AND AN OUTLET, A BY-PASS PIPE INTERCONNECTING AN OUTLET OF SAID PUMP AND SAID INLET OF SAID HUMIDITY MEASURING DEVICE TO DIVERT A SMALL STREAM OF CIRCULATING SOLVENT COMPOSITION TO SAID HUMIDITY MEASURING DEVICE, A RESERVOIR FOR WATER, A RESERVOIR FOR WASHING MATERIALS, EACH OF SAID RESERVOIRS HAVING AN OUTLET, CONTROL MEANS RESPONSIVE TO SAID HUMIDITY MEASURING DEVICE TO REGULATE THE FLOW OF SAID WATER AND OF SAID WASHING MATERIALS TO SAID CIRCULATING SOLVENT COMPOSITION, A MIXING DEVICE FOR MIXING SAID WATER, SAID WASHING MATERIALS AND SAID CIRCULATING SOLVENT COMPOSITION, SAID MIXING DEVICE INCLUDING A CONTAINER PROVIDED WITH ONE OUTLET AND FOUR INLETS WHICH ARE CONNECTED TO THE OUTLET OF SAID FIRST-MENTIONED RESERVOIR, THE OUTLET OF SAID SECOND-MENTIONED RESERVOIR, THE OUTLET OF SAID MEASURING DEVICE AND THE OUTLET OF SAID PUMP RESPECTIVELY, AND THE OUTLET OF SAID MIXING DEVICE BEING CONNECTED TO SAID WASHING DRUM.

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