US3349579A

US3349579A - Automatic washing machines

Info

Publication number: US3349579A
Application number: US313924A
Authority: US
Inventors: Geschka Hugo Werner; Gillessen Josef Leonard
Original assignee: Constructa GmbH
Current assignee: Constructa GmbH
Priority date: 1962-10-24
Filing date: 1963-10-04
Publication date: 1967-10-31
Anticipated expiration: 1984-10-31
Also published as: DE1225591B

Description

Til ed Oct. 4, 1963 Oct. 1967 I H. w. GESCHKA ETAL' 3,3 I AUQOMATIC WASHING MACHINES 5 Sheets-Sheet l Fig.

J0 wen furs H. w. GESCHKA ETAL 3,349,579 AUTOMATIC WASHING MACHINES Oct. 31, 1967 5 Sheets-Sheet 2' Filed Oct. 4, 1965 j .Jnvenios:

aa w H. w. GESCHKA ETAL 3,349,579

AUTOMATIC WASHING MACHINES Filed Oct. 4, 1963 5 Sheets-Sheet 5 it I65 United States Patent 3,349,579 AUTOMATIC WASHING MACHINES Hugo Werner Geschka, Dusseldorf, and Josef Leonard Giliessen, Unterbach, near Dusseldorf, Germany, assignors to Constructa-Werke G.1n.b.H., Dusseldorf- Oherkassel, Germany, a company of Germany Filed Oct. 4, 1963, Ser. No. 313,924 Claims priority, application Germany, Oct. 24, 1962, C 28,258; Jan. 14, 1963, C 28,903 15 Claims. (CI. 68-12) ABSTRACT OF THE DISCLOSURE Automatic washing machine has an outer drum for receiving Washing liquid, an inner drum for receiving articles to be washed rotatably mounted in the outer drum, a fresh water supply line connected to the outer drum, means for heating the washing liquid to the boiling point in the outer drum, extraction means for extracting steam formed in the drums from the boiling washing liquid, the extraction means comprising a water jet injector connected to the Water supply line and having a second conduit connected to the outer drum, program control means for controlling the operating cycle of the washing machine, thermostat switch means operatively connected to the heating means and adapted to sense the temperature of the washing liquid in the outer drum and to control the heating means in dependence thereon, and valve means disposed between the water supply line and the water jet injector, the valve means being actuatable selectively by the program control means and the thermostat switch means for supplying operating water to the water jet injector.

In the operation of domestic washing machines, and particularly double drum washing machines, it is conventional practice for the washing liquid in which the laundry is washed to be heated only to about 90 C. since otherwise there is excessive evolution of steam and other vapours. A double drum washing machine is one which has an inner drum for holding the laundry rotatably mounted Within a stationary outer drum to which the washing liquid is supplied. The steam escapes to the atmosphere from the outer drum through apertures in the machine housing and condenses on the walls of the room in which the machine is used or on articles in the room and the condensation is most undesirable and unpleasant. In addition the steam and vapours which escape from the machine frequently have an unpleasant smell and reduce visibility in the neighbourhood of the machine. Limitation of the temperature of the washing liquid to about 90 C. is undesirable because this temperature is not suificiently high to wash the laundry properly and to utilise the full bleaching action of detergents.

The object of the invention is to provide an automatic domestic washing machine in which the washing can be carried out at temperatures at which the liquid boils without the resultant steam escaping from the machine and becoming a nuisance. In accordance with the present invention the laundry is boiled in washing liquid in a drum and the steam evolved during boiling is continuously extracted from the drum by means of a pressure gradient and is condensed within the machine.

ICC

The steam which is condensed in a condensation trap in the machine may be pumped away either continuously or discontinuously during the operation of the machine. It the drum is one which is rotated for mechanical treatment of the laundry, for example the inner drum of a double drum washing machine, the rotation of the drum is preferably reduced or even stopped during the boiling operation so that the evolution of steam can be reduced correspondingly.

The invention is particularly suitable with a double drum automatic washing machine which operates on the flow principle, that is to say one in which fresh water is continuuosly or discontinuously supplied to the outer drum of the machine and a corresponding amount of dirty water leaves the drum through an overflow and is pumped away. In accordance with a further feature of the present invention, a pump or fan is arranged to force or suck steam from above the liquid in the drums when the washing liquid is boiled out through an extraction aperture in the outer drum and into a trap for condensing the steam within the machine.

A machine which works on the flow principle is particularly useful for carrying out the invention because such a machine usually has one water extraction pump for removing water from the bottom of the drum when it has to be emptied and also a flow water pump for discharging the dirty flow water from the machine, one

or other of these pumps being available to discharge the condensate from the condensation trap. In addition the pump which extracts steam from the drum may be a water jet injector which is contained in an intake line of the flow water pump, and the condensation trap may 7 also be in this intake line. Even better, however, is the arrangement in which the water jet injector is used not only to extract the steam from the drum but also as the condensation trap. The steam which is extracted from the top of the drum during boiling can then be extracted even more effectively and simply because no separate condensation trap is required.

A number of examples of domestic double-drum auto matic washing machines constructed according to the invention are diagrammatically illustrated in the accompanying drawings, in which:

FIGURE 1 is an elevation of a flow-type washing machine in which the vapours evolved during the boiling operation are extracted from the outer drum by an injector;

FIGURE 2 is an elevation of a washing machine with a fan communicating with the outer drum and leading to a condensate trap;

FIGURE 3 shows the drum system of a domestic washing machine with an open venting circuit and a condensate trap disposed immediately before a flow water p p;

FIGURE 4 is a vertical longitudinal section through 'a washing and drying machine with a water jet injector incorporatedin the emptying pump delivery port;

FIGURE 5 shows part of a washing and drying machine which is a modification of that shown in FIG- URE 4 with a water jet injection provided separately of the water emptying conduit;

FIGURE 6 is an elevation of a flow washing machine which is another modification of that shown in FIG- URE 4 with a water jet injector incorporated in a flow water pump delivery port;

FIGURE 7 is part of an electrical circuit diagram of the washing and drying machines shown in FIGURES 4 to 6; and

FIGURE 8 is a perspective view of electrical circuitry and controls corresponding to the circuit diagram of FIGURE 7.

In the double-drum washing machine shown in FIG- URE 1, the drum system which is resiliently mounted so as to be free to oscillate in the machine housing 3 by springs 1 and shock absorbers 2, consists of an outer drum 4 and a washing and spin-drying drum 5 within it. Fresh water required for the various washing operations flows through a water inlet line 6 into the outer drum. An electromagnetically operated water admission valve 7 incorporated in the water inlet line 6 is controlled by a programme controller 8, which opens and closes when necessary during washing. Depending on the washing operation in progress, the outer drum is filled with fresh water to a certain level. A number of water level controllers, for example

diaphragm pressure switches

9, 9a break the supply of current to the electromagnetic water admission valve 7 when the water level preselected by the programme controller is reached. The liquid can be heated to boiling point by an electrically operated heater 10 in the outer drum.

The washing machine illustrated operates on the flow principle. The back wall 11 of the outer drum contains an overflow aperture 12. A hose 13 connects an overflow channel 14 to a flow water pump 15 the outlet 16 of which leads to a sink 17. The overflow channel 14 contains an injector 18 and an outlet 19. The injector is taken through the overflow channel and leads vertically into the outlet 19 so that in operation it works as a water jet pump. An injector supply line 20 is connected to the water supply line 6 upstream of the water admission valve 7 and has a check valve 21 controlled by the programme controller 8. The valve 21 may be controlled alone or additionally by a thermostat 8' if required.

The check valve 21 is open during the boiling operation so that the injector is operated by the fresh water arriving via line 20- and produces a suction in the overflow channel 14. The steam and vapours evolved from the boiling of the liquid are therefore drawn out of the drum 4 through the channel 14. Some of the extracted steam and vapours condense immediately on contact with the cool surface of the injector 18 while the remainder is condensed by the injector water. The water used to operate the injector is fed to the sink 17 together with the steam condensate by the flow water pump 15. A main pump (not shown) is provided for emptying the container 4.

In the automatic washing and spin-drying machine which operates on the flow principle and is shown in FIGURE 2, the intake 22 of a fan 23 is connected to the rear wall of an overflow channel 24. The suction produced by the fan draws the vapour evolved in the outer drum during boiling into a condensate trap 25 which in this case is constructed as a drip cooler. The vapour forced into the condensate trap through the outlet 26 of the fan flows up in countercurrent through a water drip channel 27 in which the vapour condenses. The flow of water in the condensate trap 25 is controlled by the programme controller. Fresh water flows through a port 28, which is provided with a check valve, into the water drip channel from which it flows down over ribs 29. The resultant mixture of fresh water and steam condensate flows through a line 30* to a flow water outlet line 31 of the overflow channel and on to a flow water pump 32. The air extracted from the drum area with the vapour is returned to the outer drum via a connection 33 and through a line 34 after separation of the condensate. In this example, the line 34 starts beneath a detergent filler 35 and is so constructed that when the vapour is being drawn in the flow is down from the detergent filler to the drum space. This appreciably increases the etficiency of the fan 23.

The operation of the system shown in FIGURE 3 is based on the feature that a fan 36 connected to the top of the outer drum 4 produces a pressure gradient between the inside of the outer drum and atmosphere. The high pressure side 37 of the fan 36 leads to the top of the outer drum and beneath a detergent filler 39. A baffle plate 38 leads the flow of air produced by the fan into the outer drum tangentially to the washing and spindrying drum 5. This arrangement of the baffle plate 38 ensures that the detergent filler 39 is not affected by the flow of air. The latter spreads out in the outer drum 4 and then carries the vapour forming during boiling through an aperture 40 and a conduit 41 to a condensate trap 42, which is again constructed as a drip cooler. A spray 43 produces a fine water mist to permeate the mixture of air and vapour flowing through the condensate trap, so that the vapour condenses. Baffle plates 44 ensure that the mixture of air and vapour is intimately mixed with the water mist. The vapour condensate and the water supplied by the spray 43 then flow through a hose 45 to a flow water pump 46 and are discharged by it. The air flows through a channel 47 and an air outlet 48 to atmosphere.

The above-described examples of washing machines according to the invention can be modified in various ways. For example, the condensate trap outside the drum system as illustrated could be replaced by cooling coils for condensation of the vapour, situated inside the outer drum.

FIGURE 4 shows a washing and spin-drying machine which can also be used as a drying machine. This doubledrum washing and drying machine also comprises a drum system which is resiliently mounted so that it is free to oscillate in a machine housing 103 by means of springs 101 and shock absorbers 102, and which consists of a drum container 104 and a washing, spin-drying and drying drum 105. The fresh water required for the various washing operations flows through a water inlet conduit 106 to the drum container. An electromagnetically operated water admission valve 107 incorporated in the water inlet conduit 106 is controlled by a programme controller 108. The drum container is filled with a certain level of fresh water according to the type of washing operation in progress. A number of water level controllers, for example the diaphragm pressure switches 109, 109a break the supply of current to the water admission valve 107 when the water level pre-set by the programme controller is reached. The liquid can be heated to boiling point by an electrical heater 110 within the drum container. A venting line 111 connected to a delivery line 113 of an emptying pump 114 at a point 112 is connected to the drum container above the level of liquid. The venting line 111 prevents the drum container from siphoning empty during overflow rinsing with a high level of liquid. An extraction system including a water injector 116 is disposed in a downwardly extending branch of the delivery line 113 of the emptying pump and is used to extract the vapours and foam during boiling and drying.

A drier fan 117 is provided in the machine housing 103 and its outlet line 119 contains an air heater 120. The fan outlet line consists partially of a resilient material so that it can follow the movement of the drum container 104, which is free to oscillate. A tubular member 121 fitted in the bottom part of the drum container, communicates with the siphon-shaped outlet line 119, the bent apex 122 of which is situated sufficiently above the level 123 of liquid in the drum. The tubular element 121 has cooling ribs 124, the use of which will be explained. The fan intake 125 leads into the drum container at the top at 126. Thus, during drying it is possible to maintain a substantially closed hot-air circuit extending from the fan to the drum container and back from the latter to the fan.

Above the drum container 104 is a detergent filler 127, which is surrounded by a resilient ring 128. The ring leads into a detergent dish 129 connected on the one hand via a sleeve 130 to the drum container 104 and on the other hand via a conduit 131 to the cold water supply line 106 through a branch (not shown) provided with a valve. The detergent filler 127 is closed by a cover 132, on the inside of which is fastened .a venting valve 134 controlling venting apertures 133. If a suction is formed in the drum container, air can flow to the drum container over the path shown in chain-dotted lines; if there is an excess pressure in the drum container, for example during boiling, the diaphragm valve 134 interrupts the air flow path shown in broken lines. If the excess pressure in the drum rises to a predetermined critical value for some unforeseen reason, for example if the extraction system fails, the cover 132 is opened under the influence of the pressure inside the drum container so that the valve is moved into an inoperative position. One or more thermostats 135 are provided in the drum container, although one multi-stage thermostat maybe used instead of a number of thermostats.

If the washing and drying machine is operated at the liquid boiling temperature, the vapours evolved rise in the drum container. They collect mainly in the top of the drum container 136. If pressure water is now introduced into the injector line 138 by opening the valve 137, a suction is formed in the delivery line 113 of the emptying pump 114 and in the venting line 111. Since the resistance to the flow of vapours and foam in the venting line 111 is less than in the delivery port 113 filled with the liquid, the vapours and foam are extracted by way of the venting line 111..They flow to the injector 116. The vapour condenses on the cold injector wall parts and as a result of contact with the injector operating water, whereupon the vapour condensate together with the foam residues and the operating water are forced to the outlet 139.

During the boiling process, the washing liquid in the tubular element 121 is at the same height as the liquid in the drum container. 104. The liquid in the tubular member during the boiling of the clothes can be kept at a temperature below boiling point by means of the cooling ribs 124 and this prevents any escape of vapour to the drying fan 117. The cooling ribs 124 need reduce the liquid temperature by only 3 to 4 C., since such a temperature difference is suflicient to prevent any boiling of the liquid at this place. If the drum container is emptied, the liquid in the tubular element 121 flows off to the emptying pump 114, by which it is forced into the outlet 139.

As will be apparent from FIGURE 5, a separate suction line 140 for the Water jet injector 116 may be provided in addition to the venting line 111 for extraction of the vapours and foam, the suction line 140 also branching off in the top part 136 of the drum container 104. In this case, therefore, the venting line 111' is used only to vent the delivery port 139 during overflow rinsing so as to prevent any siphoning efrect. The water jet injector 116 in this case is therefore situated with its suction line 140 and a condensate water and foam delivery line 141 parallel to the pump delivery port 139 and its venting line 111.

As shown in FIGURE 6, in a flow type washing machine the injector 116 may also be disposed in a line 142 of a flow water pump 143. The suction line 144 of the water jet injector 116 is again connected to the top of the drum 104 level with the top 136. This ensures that only two outlets are used in a flow-type washing machine as was conventionally the case, namely the outlet 145 for the drum container emptying pump and the outlet 146 for the flow water pump. Instead of the flow water pump 143, the injector water jet pump 116 may be used alone, since it can also be used to extract flow water. The water consumption would increase very sharply in such a case,

kg. of clothes, provision is made for at least 3 litres but 6 not more than 6 litres of water to be used per minute for the water jet injector, i.e., for extraction and condensation of the vapour or for extraction of the foam from the drum container.

When a certain washing programme is switched on, for example for fine wash, the rhythm of rotation of the washing drum may also be changed in a conventional manner, intervals of appropriate length being maintained during washing, for example by means of a cam-controlled switch 157. In the circuit diagram shown in FIGURE 7, the press-

buttons

147, 148, 149 and 150 are used to set the washing machine to different types of wash. If the press-button 147 is operated, a thermostat switch 151 responding, for example, to 45 C. is incorporated in the line 152 to the heating contacts 153. When the liquid reaches the pre-set temperature of 45 C., the thermostat switch 151 opens the circuit, so that the heater contacts 153 open and the heater 154 is switched off. Operation of the press-button 147 closes a switch 155 which by way of a line 156 selects the cam-controlled switch 157 which extends the time of the intervals between reversal of the washing drum to clockwise and anti-clockwise movement. In an automatic washing machine employing a boiling process, the washing drum should change its rhythm of rotation before the liquid reaches the boiling temperature. The thermostat must not switch the heater 01f however. In the present example, this object is achieved by the fact that when the press-button 150 is operated closure of a switch 158 operates the heater 154 without any thermostat control, i.e., only with a time-linked control by the programme switch 158'. At the same time, closure of a switch 159 alters the rhythm of rotation of the washing drum drive by means of a changeover switch 160 also operated by a 90 C. thermostat switch 159', since a change is made from a cam disc 161 which is operative during the washing operation and which provides the normal rhythm of rotation, to a cam disc 162 which provides the restricted rhythm of rotation for boiling the clothes. Closure of the

switches

158 and 159 on operation of the press-button 150 also switches-in the circuit which leads to a switch 163 and which belongs to a water admission valve 164 of the water jet injector 116. As soon as the thermostat 159' switches over when the liquid temperature exceeds 90 C., the switch 163 is closed and hence the water admission valve 164 is energised so that the water jet injector 116 is rendered operative. After a predetermined time for boiling has elapsed, the programme controller sets the machine to rinsing, so that the thermostat switch 159' returns to its position illustrated. After the wash has been spun, the drying operation is finally carried out, a cam disc 165 also operated by the programme controller switching on or opening the water admission valve 164 to the water jet injector 116.

FIGURE 8 shows an advantageous arrangement of the essential parts of the extraction system, namely the pressbutton switch 150 incorporated in a control panel, the thermostat switch 159' following the switch 150, the water admission valve 164 or 13-7, and the water jet injector 116. As shown diagramatically on the right in the drawing, the thermostat switch 159' may be replaced by a switch 166 which is operated in a time-linked relationship by the programme controller.

The machines can also be modified in various other ways. For example, the drying air current may be introduced into and discharged from the drum container 104 at some other place. The water-level-

dependent switches

109, 109a may be used directly or indirectly to switch the

water admission valve

137 or 164. This can be carried out by extracting a certain quantity of liquid from the container 104 at a temperature of 90 C. before boiling. This reduces the pressure on one of the diaphragm pressure units belonging to the water level switches 109, 109a, so that when a lower level of liquid is reached the injector or

water admission valve

137 or 164 is switched on directly or indirectly by the water level switch, the boiling process being carried out in a liquid at a lower level than the 6 normal washing operation. The advantage of this step is that less power is required to heat the liquid for boiling the clothes. The water admission valve to the injector 116 can be switched on by an operating variable or in a time-linked relationship by the programme controller.

We claim:

1. An automatic washing machine comprising a housing, an outer drum resiliently mounted in said housing, an inner drum rotatably mounted within said outer drum, wall parts of said outer drum defining an extraction aperture in said outer drum, a condensation trap within said housing, a conduit for supplying cold water to said condensation trap to condense said steam, a stop valve in said conduit and a thermostat responsive to said liquid temperature and adapted to control said stop valve, and pressure gradient producing means operatively connected to said extraction aperture and to said condensation trap whereby steam forming above the liquid in said drums when said washing liquid is boiled is extracted out through said extraction aperture and is condensed in said condensation trap.

2. An automatic washing machine comprising a housing, an outer drum resiliently mounted in said housing, an inner drum rotatably mounted within said outer drum, wall parts of said outer drum defining an extraction aperture in said outer drum, a condensation trap within said housing, a water extraction pump adapted to remove water from said drum, a conduit extending between said extraction aperture and said water extraction pump, said condensation trap being provided within said conduit, and pressure gradient producing means operatively connected to said extraction aperture and to said condensation trap whereby steam forming above the liquid in said drums when said Washing liquid is boiled is extracted out through said extraction aperture and is condensed in said condensation trap.

3. An automatic washing machine comprising a housing, an outer drum resiliently mounted in said housing, an inner drum rotatably mounted within said outer drum, wall parts of said outer drum defining an extraction aperture in said outer drum, a condensation trap within said housing, pressure gradient producing means operatively connected to said extraction aperture and to said condensation trap whereby steam forming above the liquid in said drums when said washing liquid is boiled is extracted out through said extraction aperture and is condensed in said condensation trap, a water discharge line leading from said outer drum, a water extraction pump adapted to remove water from said outer drum through said discharge line, and a fresh water line leading to said outer drum, said pressure gradient producing means being a water injector incorporated in said discharge line and adapted to be operated by water from said fresh water supply line.

4. An automatic washing machine comprising a housing, an outer drum resiliently mounted in said housing, an inner drum rotatably mounted within said outer drum, wall parts of said outer drum defining an extraction aperture in said outer drum, a condensation trap within said housing, pressure gradient producing means operatively connected to said extraction aperture and to said condensation trap whereby steam forming above the liquid in said drums when said washing liquid is boiled is extracted out through said extraction aperture and is condensed in said condensation trap, both said pressure gradient pressure means and said condensation trap being formed by a water jet injector and means being provided connecting said injector to the top of said drum.

5. Automatic washing machine comprising an outer drum for receiving washing liquid, an inner drum for receiving articles to be washed rotatably mounted in said outer drum, a fresh water supply line connected to said outer drum, means for heating the washing liquid to the boiling point in said outer drum, extraction means for extractin g steam formed in said drums from the boiling washing liquid, said extraction means comprising a water jet injector connected to said water supply line and having a suction conduit connected to said outer drum, program control means for controlling the operating cycle of the washing machine, thermostat switch means operatively connected to said heating means and adapted to sense the temperature of the washing liquid in said outer drum and to control said heating means in dependence thereon, and valve means disposed between said water sup ly line and said water jet injector, said valve means being actuable selectively by said program control means and said thermostate switch means for supplying operating water to said water jet injector.

6. Washing machine according to claim 5, wherein said water jet injector serves simultaneously as means for producing a pressure gradient and as a condensation trap whereby the steam formed above the washing liquid in said drums is removed from said drums and is condensed.

7. A machine according to claim 5, further comprising a pump adapted to discharge water from said outer drum, an outlet line from said outer pump and a venting line connecting said outlet line with the top of said outer drum, said water jet injector being arranged in said outlet line downstream of said venting line whereby steam is drawn from said outer drum through said venting line to said injector.

8. A machine according to claim 7 wherein said valve means comprises an electromagnetic water admission valve, an electrical control circuit for said electromagnetic water admission valve, and a manually operated switch, and said thermostat switch means comprising a second switch in series in said control circuit and a thermostat adapted to sense the temperature of the liquid in said drum and to control said second switch in dependence thereof.

9. A machine according to claim 7, wherein said valve means comprises an electro-magnetic water admission valve in the supply line for the water which operates said water jet injector, an electrical control circuit for said electromagnetic water admission valve, and a manually operated switch, said thermostat switch means comprising a second switch in series in said control circuit, a timing device controlling said second switch and said program control means connected to said timing device for controlling the same.

10. A machine according to claim 8, wherein said thermostat is adapted to keep said second switch closed at temperatures above C.

11. A machine according to claim 10, further comprising an electrical control circuit for said heating means, a heater switch in said heater control circuit, a timing device controlling said heater switch, said program control means connected to said timing device for controlling the same, and a further switch in series with said heater switch, said further switch adapted to be closed upon operation of said manually operated switch and adapted to keep said heater on after said thermostat has operated said second switch until opening thereof by said heater switch.

12. A machine according to claim 11, further comprising a rotating cam disc adapted to be brought into operation by said thermostat whereby the rhythm of rotation of said inner drum is altered when said liquid temperature exceeds 90 C.

13. A machine according to claim 12, further comprising an overriding switch for said water admission valve of said water jet ejector, a control for said heating means, and a press button control panel carrying said overriding switch, said heater control, said manually operated switch and said cam disc.

14. A machine according to claim 5, further comprising a venting conduit from said outer drum, a venting valve arranged in said vending conduit whereby said outer drum is vented during operation of said water jet ejector, means ensuring closure of said venting valve upon build up of on excess pressure in said outer drum and means moving said venting valve into an inoperative open position when 9 10 a predetermined maximum pressure in said outer drum References Cited is exceeded- NIT TE PATENTS 15. A machine according to claim 5, further compris- U ED STA S ing a closed circuit for drying air through said outer drum, $35 2??? 111 d a CllC aing fan a apted to pass hot arr through sax 5 3,113,445 12/1963 Williams et a1 68 18X circuit, a pipe leading to said outer drum and forming part of said circuit, said pipe having parts formed in the FOREIGN PATENTS shape of an inverted U with the apex of the U above the 1 287 987 2/1962 France intended maximum level of liquid in said drum, and cooling ribs disposed on one arm of said U immediately adw WILLIAM L PRICE Primary Examiner jacent said outer drum.

Claims

1. AN AUTOMATIC WASHING MACHINE COMPRISING A HOUSING, AN OUTER DRUM RESILIENTLY MOUNTED IN SAID HOUSING, AN INNER DRUM ROTATABLY MOUNTED WITHIN SAID OUTER DRUM, WALL PARTS OF SAID OUTER DRUM DEFINING AN EXTRACTION APERTURE IN SAID OUTER DRUM, A CONDENSATION TRAP WITHIN SAID HOUSING, A CONDUIT FOR SUPPLYING COLD WATER TO SAID CONDENSATION TRAP TO CONDENSE SAID STEAM, A STOP VALVE IN SAID CONDUIT AND A THERMOSTAT RESPONSIVE TO SAID LIQUID TEMPERATURE AND ADAPTED TO CONTROL SAID STOP VALVE, AND PRESSURE GRADIENT PRODUCING MEANS OPERATIVELY CONNECTED TO SAID EXTRACTION APERTURE AND TO SAID CONDENSATION TRAP WHEREBY STEAM FORMING ABOVE THE LIQUID IN SAID DRUMS WHEN SAID WASHING LIQUID IS BOILED IS EXTRACTED OUT