EP0043361A1 - Vacuum drier - Google Patents

Abstract

A drier which reduces the energy consumption by more than half and which ensures a remarkable reduction in the drying period, employing: - a vessel (1) communicating with a vacuum generator (3); - a driving means (5) for the vacuum generator creating and maintaining an atmospheric pressure reduction in the vessel; - electrical radiative heating (10) to make the boiling under reduced pressure very fast; - a rotary drum (2) to equalise the heating; - a thermostat (16) and a control button (15) for selecting the heating and making it uniform; - a condensing device which decreases enormously the work of the vacuum generator (3) by precondensation of virtually all the water vapour, by virtue of the condensing circuit (17) and of the condensate box (9) which maintains in its upper part an empty space (20) permitting communication between the vessel (1) and the vacuum generator (3); - valves (23, 24, 25), when the device is incorporated in a clothes-washer and no longer in an individual drier. <IMAGE>

Description

The present invention relates to a device intended in particular for drying wet laundry.

Known driers are based on the principle of producing heat to evaporate water, the heat being produced for example by jet of hot air, or by electrical resistances radiating heat. Heat production consumes a relatively large amount of energy. In addition, for the drying of certain textiles made of synthetic materials, excessive local heat must be avoided, otherwise the substance of the synthetic materials will be damaged, whereby the drying of the linen in these materials is relatively slow.

The first problem which the invention aims to solve is to provide a drying device which truly consumes a minimum of energy, and which ensures rapid drying, without the risk of damaging the materials of the laundry. The second problem that the invention aims to solve is to align the drying capacity of the laundry, in an automatic washing machine, with the washing and spinning capacity, since the known washing machines have a capacity much less drying than their washing and spinning capacity.

To solve these problems, the invention provides a completely different drying method than that used in known driers. The method used according to the invention consists in producing and maintaining an atmospheric depression in an enclosure, in order to cause the evaporation of water therein by boiling at a temperature substantially below 100 ° C.

The water in the linen is also provided with a calorific contribution intended to make its boiling as rapid as possible. Finally, a device condenses the water vapor before it arrives in the vacuum generator, so that the latter must only suck traces of vapor, which reduces the work of said generator to a strict minimum.

This method is implemented, according to the invention, by means of a device which comprises a tank resistant to atmospheric pressure, in which is mounted a non-waterproof drum to contain the laundry to be dried.

The internal volume of the tank is in communication, by a piping, with a vacuum generator (for example a vacuum pump or a water pump) arranged so that, when activated, it creates and maintains a vacuum atmospheric, sucks the water vapor produced in the tank, and evacuates this water vapor. The vacuum generator can for example consist of a vacuum pump or a water pump, the first being actuated by a motor, the second by a water supply. A resistive device heating by radiation and controlled by a thermostat is provided to radiate in the tank a heat which maintains there the temperature chosen for the drying of the linen. This heat is mainly intended to make the boiling water of the laundry as fast as the capacity of evacuation of water vapor by the vacuum generator allows. The steam outlet from the tank is connected to a condensing device, to condense almost all of the steam, so that only traces of steam have yet to be drawn in by the vacuum generator.

Finally, a ballast is provided which allows the re-entry of air into the tank after drying the laundry, in order to rebalance the pressures. Uniform heating of the linen is ensured by the rotation of the drying drum.

The advantage of the arrangement according to the invention is that it requires only a minimum consumption of energy, combined with a much faster drying of the laundry, at a controlled and moderate temperature which does not risk causing damage. linen materials.

The drying device according to the invention can be produced in an individual dryer, or be incorporated in a washing machine. In the latter case, valves are also provided, on the one hand, to protect the vacuum generator as well as the steam condensation device, against flooding with water during the washing, rinsing and washing operations. 'spinning of the laundry, and on the other hand to close the water inlet and outlet pipes, during the operation of the vacuum generator. In this embodiment, the arrangement according to the invention has the additional advantage of aligning the drying capacity of the laundry with the washing and spinning capacity, which is not generally the case in washing machines. traditional.

• - la figure 1 illustre schématiquement la constitution d'un mode de réalisation préféré du dispositif de l'invention ;
• - la figure 2 illustre schématiquement l'agencement du dispositif de séchage selon l'invention, incorporé dans un lave-linge.

The invention is explained in more detail below, with reference to the attached drawings, in which

• - Figure 1 schematically illustrates the constitution of a preferred embodiment of the device of the invention;
• - Figure 2 schematically illustrates the arrangement of the drying device according to the invention, incorporated in a washing machine.

Referring to Figure 1 we see, shown schematically, the constitution of the drying device proposed in its preferred embodiment. The reference numeral 1 designates a tank inside which is mounted a rotary drum 2 intended to receive wet laundry.

The filling in wet linen and the removal of the dried linen is carried out here by the sealed door 11 of the tank 1, and by the door 12 of the rotary drum 2. According to the invention, the steam outlet of the tank 1 is found in communication with a vacuum generator 3, via a pipe 4.

In this example, the vacuum generator is constituted by a vacuum pump 3 actuated by an electric motor 5, which can advantageously also drive the rotary drum 2. When the pump 3 is started, the vacuum which is created in the tank 1 causes the laundry water to evaporate, and the produced water vapor is sucked by the pump.

An exhaust opening 6 allows the evacuation of traces of water vapor, all the rest of this vapor being condensed by means of the vapor condensation device, the operation of which will be described below.

A ballast 13 allows the entry of the air necessary to rebalance the pressures, when the drying is complete.

The tank 1 is also provided with a resistive device, schematically shown in 10, intended to be supplied by an electric current in order to radiate heat in the tank 1, when the vacuum generator is operating, this for the purpose of make the water boil in the laundry as fast as the large capacity for evacuating water vapor through the vacuum generator assisted by the condensing device allows.

The resistive device heating by radiation 10 is necessary to accelerate the boiling of the water of the linen, to the selected temperature degree tolerable by the treated textiles, throughout the duration of the boiling and vacuum drying cycle.

The resistive radiant heating device 10 is advantageously fixed to the bottom of the tank 1, and protected by a sealed glass 14 but transparent to infrared radiation.

A switch 15 is provided to control the supply of the electric motor 5, which must drive the vacuum pump 3, but can also advantageously drive the rotary drum 2.

This switch 15 also controls the powering of the resistive heating device 10. The switch 15 can obviously be placed on the usual control panel.

The heating device 10 is advantageously supplemented by a thermostat shown diagrammatically at 16, fixed in the tank 1, to interrupt and reset the heating device 10 periodically and automatically, in order to keep the temperature in the tank 1 stable.

Preferably, the temperature to be maintained in the tank should not be less than about 60 ° C. Indeed, it has been observed that below 60 ° 0 the speed of the drying cycle decreases due to the strong expansion of water vapor at very low pressure,

unless you use a fairly large steam hose. In order to minimize the work of the vacuum generator, the steam pipe 4 is connected to the inlet of the condensing circuit 17 of an condenser 8. The latter has a cooling water inlet 18 and an outlet cooling water 19.

The condensation circuit 17 opens into a condensate box 9, which has a sufficient capacity to contain all the condensate coming from the drying of the laundry contained in the drum 2, while leaving in its upper part a free space 20 by which the circuit of condensation 17 is connected to the vacuum pump 3 (or to any other vacuum generator) by the pipe 21. The pump 3 can thus always remain in communication with the internal volume of the tank 1, without risk of sucking the condensate . The condensate box 9 is provided with a drain 22.

Thanks to the condenser 8 and the condensate box 9, almost all the steam produced in the tank 1 is condensed, and only traces of steam must still be sucked by the pump 3, which produces the considerable advantage of reducing the pump work, and therefore energy consumption, to a minimum.

The vacuum generator 3 and the condenser 8 with its condensate bundle 9 can be easily housed in the traditional covering of a conventional dryer of usual dimensions.

In the foregoing is described an individual clothes dryer, but it is understood that the arrangement according to the invention can also be implemented in a washing machine, with however the adaptations set out below with reference to FIG. 2 .

The motor 5, which drives the vacuum pump 3, will advantageously be designed to also provide the driving force for all the operations prior to drying the laundry, operations such as the prewash of the laundry, its washing, its rinsing and its spinning, all carried out in the tank 1, in which the rotary drum 2 can be driven by the single motor 5.

Etanohéité around a sliding or rotating axis was until now inconvenient to achieve, despite the finest rubber seals. Ferrofluids have recently provided an ideal solution, the bearing is made of a strong magnet which constantly brings the magnetic lubricant back into place, so that it is possible to create a vacuum on one side, without there being any as much the slightest air intake by the axis. Therefore, the use of such a joint is strongly recommended here.

The other sealing problems are resolved as follows.

A valve 23 is inserted in the duct 4, and protects the vacuum pump 3, as well as the entire condensation device, against flooding with water, during the various operations other than drying the linen.

On the other hand, to ensure the etanohéité of the tank 1 during the drying of the linen, valves 24 and 25 are inserted respectively in the water inlet pipe 26 and in the wastewater discharge pipe 27. A means switch, not shown not to overload Figure 2, is used to keep the valve 23 closed when any of the valves 24 and 25 is open, and to open this valve 23 only when the valves 24 and 25 are closed . The cooling water inlet 18 of the condenser 8 is advantageously connected in diversion to the clean water inlet 26, and the cooling water outlet 19 of the condenser is advantageously connected to the waste water outlet 27.

The advantages resulting from the arrangement according to the invention are shown by the comparative measurement results given below.

The vacuum prototype according to the invention comprises a vacuum pump with a capacity of 50 liters / minute, driven by an electric motor with a power of 0.25 CV, and a heating resistance of 1300 watts.

The condensing circuit of this prototype consists of a 40 cm high spiral.

This prototype was compared to a commercial automatic washer-dryer, with a capacity of 2 kg of dry laundry per cycle. drying. The experimental measurements were carried out for two drying cycles: a cycle A for cotton and colors, and a cycle B for synthetic textiles.

In the vacuum prototype, the drying temperature is 70 ° C for cycle A, and 60 ° C for cycle B

The results show that the vacuum drying method according to the invention results in a very significant reduction in energy consumption, and ensures a remarkable reduction in the duration of the drying cycle.

Claims (4)

1. Vacuum drying device, comprising a sealed tank (1) in which is mounted a non-waterproof rotary drum (2) to contain a wet material, the tank having an outlet (4) for the exhaust of steam - characterized in that it further comprises a vacuum generator (3) connected to the steam outlet (4) of the tank (1), a drive means (5) for the vacuum generator , in order to create and maintain an atmospheric depression inside the tank (1), a radiation heating device (10) arranged in the tank (1) so that, when it is supplied with an electric current, it radiates heat into the interior volume of the tank, and a switching device (15) connected to supply the vacuum generator drive motor (3) and the radiation heating device (10). 2. Drying device according to claim 1, characterized in that it further comprises a steam condenser (8) enclosing a steam condensation circuit (17), which is connected to the steam outlet (4) of the tank (1), in order to condense almost all of the water vapor coming from the drying of the laundry, a condensate box (9) which is connected to the outlet of the condensation circuit (17), with a free space (20 ) left in the upper part of the condensate box (9), this free space communicating the interior of the tank (1) with the vacuum generator (3) via the steam outlet (4) and the steam condensing circuit (17), so that the vacuum generator (3) should only suck up traces of uncondensed water vapor which have not been collected in the condensate box (9 ); finally, a draining means (22) for periodically emptying the condensate box (9). 3. A drying device according to any one of claims 1 and 2, further comprising means (13) for rebalancing the pressures after a drying cycle. 4. Drying device according to any one of claims 1 to 3, incorporated in a washing machine, then characterized in that it further comprises a first valve (23) inserted in the steam pipe (4) which connects the tank (1) to the vacuum generator (3) via the condensing device according to claim 2, and second valves (24 and 25) inserted respectively, the first in the clean water supply pipe (26), and the second in the waste water discharge pipe (27), with means for keeping the first valve (23) closed when the second valves (24 and 25) are open, and for only opening the first valve (23 ) only when said second valves (24 and 25) are closed.

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