EP1832678B1

EP1832678B1 - Energy saving household clothes drying machine

Info

Publication number: EP1832678B1
Application number: EP06110696A
Authority: EP
Inventors: Ugo Favret; Flavio Noviello
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2006-03-06
Filing date: 2006-03-06
Publication date: 2012-06-13
Anticipated expiration: 2026-03-06
Also published as: EP1832678A1

Description

This invention refers to a kind of clothes drying machine, preferably of the type for use in households, which is provided with improved means for circulating the drying air to ensure high energy efficiency.
The machines, which the present invention refers to, are generally known in the art. They have on the other hand been described, along with a detailed discussion of a technical nature on the advantages and the drawbacks of a number of different variations in the design and general embodiment thereof, in the European Patent Application no. EP 04106204.3 filed by this same Applicant with the title "Low noise Household Clothes Drying Machine" and published as EP 1 666 657 A1 , to which reference should therefore be made for greater convenience and brevity in this description.
It should however be right away appreciated that, while the above-cited European Patent Application refers to condenser-type clothes drying machines, which are well known in their peculiarities to all those skilled in the art, so that they do not need any further explanation here, the present invention applies in the broadest sense to the generality of clothes drying machines of the tumbler-type, i.e. provided with a rotating drum and flown through by a flow of appropriately heated-up drying air, which is blown into and through the rotating drum via an appropriate opening to eventually leave said drum through a second air-removal opening. In this sense, the present invention therefore applies also to the so-called exhaust-type clothes drying machines, in which the air is taken from the outside ambient, duly heated up, blown into the rotating drum, removed from the same rotating drum and, eventually, exhausted again into the outside ambient, as opposed to what occurs in condenser-type clothes drying machines, in which the air is on the contrary caused to circulate in a closed-loop circuit that includes a suitable condenser arrangement, so as this is illustrated symbolically in Figure 1.
Both condenser-type and exhaust-type clothes drying machines share - further to the rotating drum - a common operating feature, i.e. the circumstance that in both cases there are provided an air delivery or inflow conduit and an outflow conduit, along with related openings arranged in the walls of the drum, through and in which the drying air is caused to circulate with the aid of means largely known as such in the art.
In connection with both types of clothes drying machines, an usually neglected drawback should be duly pointed out here. Reference is made here to the fact that the coupling between the drying air delivery conduit and the related inflow opening in the drum, as well as the coupling between the drying air exhaust conduit and the related outflow opening in the drum are provided with appropriate annular gaskets, e.g. of felt or some other low-friction and highly deformable material, as indicated at G 1 and G2, respectively, in Figures 1 and 2.
These gaskets, however, give generally rise to air leakages, which may reach values of up to approximately 20 percent of the total air flow rate.
Even in exhaust-type clothes drying machines, anyway, the problem of drying air leaking through the gaskets between the conduits and the drum is a rather serious and generally acknowledged one. As a matter of fact, if the exhaust air, instead of being totally conveyed and exhausted into the outside ambient, comes to be partly released inside the machine, this would imply serious as far as the safety, the efficacy and the functional state of the machine itself are concerned, owing to the high moisture content in the exhaust air flowing out of a drying drum.
As far as condenser-type clothes drying machines are concerned, in which the drying air is recovered and continuously circulated in a closed-loop circuit, basically to the purpose of recovering the thermal energy contained therein, the above-cited problem has a different purport. These machines are in fact so designed as to desirably allow the totality of the moisture contained in the drying air to be removed therefrom, so as to ensure a quick and perfect drying of the clothes. However, for this aim to be reached, it is of the utmost importance that the flow of the drying air is entirely conveyed into and through the condenser. Now, this most obviously implies that there are no losses and/or leakages of drying air at the gaskets provided as sealing means between the drying air circulation conduits and the drum.
In condenser-type clothes drying machines, therefore, a loss of a significant portion of the drying air at or through these gaskets generates a corresponding loss of energy efficiency, which is heavily detrimental as far as the quality and the performance levels of currently produced clothes drying machines are concerned, and a low level of moisture released into the surrounding ambient.
In the cited European Patent Application this drawback is effectively reduced by containment means adapted to enclose the drum, together with the respective motor and the driving belt, within a common space that is substantially closed outwardly.
However said containment means, even if effective both from the point of view of noise reduction and energy saving, turns to be quite expensive due to the appreciable amount of material required and in the general production costs.
EP 1559827 discloses a basket for a laundry dryer machine or washer dryer of the type comprising a basket or drum suitable to house the laundry and provided with an Inlet aperture for a drying airflow, a system of ducts with associated ventilator means suitable to convey said airflow, through said Inlet aperture Into said basket, heating means arranged In the airflow upstream from the Inlet aperture and suitable to heat the air before it enters the basket. The basket comprises deflector means suitable to deviate In a permanent way at least a portion of the airflow against a side wall of the basket, wherein said side wall is suitable to reflect the portion of the airflow towards the inside of the basket.
DE 196 16 634 discloses clothes dryer, as an electrical domestic appliance, has a circular drying air feed In the rear wall of the drum. The container insert, placed In the interior of the drum, is cylindrical to match the circular drying air feed. The drying air feed is divided into two sections to deliver the air to the centre and to the outer peripheral ribs within the drum, to pass through perforations In the ribs Into the drum.
DE 39 18 560 discloses a laundry drier has a drum which contains the laundry and which can be driven In rotation about an axis. A current of air passes through a space inside the drum. The current of air enters the drum through at least a first opening. One or more drivers are arranged inside the drum. In order to obtain a laundry drier of shallow depth, the air current passes from the first opening into the driver(s) and then through openings In the driver(s) Into the space inside the drum.
US 2 670 549 discloses a dryer comprising an one air-impelling means adapted to draw air from the exterior of the drum, while other air-impelling means is adapted to draw air from some other source such as interior of the drying chamber, the two quantities of air are mixed in the outer portion of the air chamber and the mixture is then forced into the drum for drying the laundry therein.
It would therefore be desirable, and it is actually a main purpose of the present invention, to provide a clothes drying machine of either the condenser type or the exhaust type, which is particularly effective in the energy consumption, without being too much expensive in the production costs.
It would be further desirable, and it is another purpose of the present invention, to provide a clothes drying machine, in particular of the condenser type, in which the above-described losses and leaks of moisture-laden air from the drying air circulation circuit are avoided in almost a radical, total manner.
According to the present invention, these aims, along with further ones that will be apparent from the following description, are reached in a clothes drying machine incorporating the features as recited in the appended claims.
Anyway, features and advantages of the present invention will be more readily understood from the description that is given below by mere way of non-limiting example with reference to the accompanying drawings, in which:

Figure 3 is a median vertical-section view through the axis of the drum of a first embodiment of a clothes drying machine according to the present invention, as illustrated in a symbolical manner;
Figure 4 is a schematic and transparent perspective view of the drum of the previous figure, showing specifically an elevator according to the invention,
Figure 5 is a rear view of the drum shown in Figure 4,
Figure 6 is a perspective detailed view of the elevator of fig. 5,
Figure 7 is a front view, taken from the drum axis "X", of the elevator of fig. 6.-
Figure 8 is a median vertical- section view through the drum axis of a different embodiment of a machine according to the invention.

In a clothes drying machine according to a prior-art embodiment there is provided a drum 1 adapted to hold the clothes to be dried, to which there is associated a delivery conduit 2 letting the drying air into the drum through an appropriate inflow opening 3, an air outlet or exhaust conduit 4 removing the drying air from the interior of the drum through a corresponding outflow opening 5, wherein said conduits 2 and 4 are joined to each other via a condenser 6, which is adapted to cause the moisture contained in the drying air flowing therethrough to condense, said condenser being furthermore flown through by a flow of "cold" air, i.e. air taken in from the outside ambient and sent to said condenser 6 via a corresponding cooling conduit 16.
It should of course be appreciated that, as already pointed out hereinbefore, the condenser 6, along with said cooling conduit associated therewith, is cited here to mere illustrative and exemplifying purposes in connection with an embodiment and a particularly advantageous application of the present invention, since these parts might equally be omitted, i.e. not necessarily be provided, in the case that the clothes drying machine is of the exhaust type.
According to the present invention, and with reference to fig. 3, the preferred embodiment of the drying machine is provided with the following features:

1) Behind said drum a substantially cylindrical element 20 is defined, which is coaxial with the drum axis, and whose front wall 21 is a portion of the rear wall of the drum, which takes the same numerical identification 21, being the same physical means; the opposite vertical wall, which from here on will be called "base", may be the back wall is a portion of the back wall 22 of the machine cabinet, and the lateral cylindrical strip 23 is implemented so as to close in an almost hermetic way such cylindrical element 20.
In the facts it is not possible to fully close such cylindrical element 20 between the drum rear wall and said cylindrical strip 23, as the drum rear wall rotates with the drum itself, while said cylindrical strip is firmly joined with the back wall of the machine; therefore it is needed to let, between said cylindrical strip and the drum rear wall, a small ring shaped gap 24, which allows the relative motion and without slithering between said elements.
2) The elevators 30, usually arranged inside the drum according to the prior art, are not closed on their sides, but they are open laterally, so that each of said elevators shows a pair of opposite openings on their back and on their front respectively 31, 32.-
3) At last, the drum rear wall 21 is provided with a plurality of through-apertures 25 (figures 4, 5) arranged in such positions so as to exactly correspond to the positions of the respective elevators, so that the rear openings 31 of the elevators are mating said apertures 25; in conclusion it will be soon clear that the inner volume of said elevators is directly connected with the inner volume of said substantially cylindrical element 20.
Moreover it will be easily observed that said cylindrical element 20, to be able of collecting the drying air-flow, escaping from the ring-shaped gap between the drum rear wall 21 and said inflow opening 3, and to lead said drying airflow straight into said elevators, has to show a diameter about of the same size of the drum diameter.
As far as the central bodies of said elevators are concerned, they do not stretch till the drum front wall 26, but they terminate before it, so that the front openings 32 get directly onto the drum inner volume. The invention operation will be now clear: in the facts the drying hot air-flow, which gets off the ring-shaped gap between the drum rear wall 21 and the conduit 2 of the drying air coming from the heating resistor 42, is directly collected by the almost hermetic chamber constituted by said cylindrical element 20, and from here it immediately spreads into said elevators across said drum through-apertures 25 and the openings 31 of the corresponding elevators.

As the heat is transferred more directly and more effectively by conduction than by convection, as well known, and as said elevators show towards the inner drum a not negligible surface area, it comes that a remarkably amount of heat is directly brought on and into contact to the drying load, through the elevators hot surface.
The final effect is therefore a better aptitude of transferring heat from the hot air to the drying load, with a general improvement of the drying performances.
As far as the air circulation inside the elevators is concerned, it is obviously allowed by said front openings 32, through which the drying air flow, previously blown into the respective elevators, escapes and directly penetrates into said drum.
To sum up there is no loss of drying hot air, but by means of the instant invention the heat only therein contained is transferred to the drying load, so achieving a better efficiency.
Of course the invention may assume other and different embodiments which however can identically exploit the present teaching; for example, with reference to fig. 8, said base of said cylindrical element 20 may even be not a proper portion of the rear wall 22 of the machine cabinet, but it may consist as well of a specific wall 22A, distinct and separate from said rear wall 22.

Claims

Front-loading clothes drying machines comprising a drum (1) holding the clothes to be dried, an inflow opening (3) that opens into said drum, a delivery conduit (2) that conveys the drying air Into said drum through said inflow opening gaskets (40) provided as sealing means between said delivery conduit (2) and said drum(1), an outflow opening (5) adapted to allow the drying air to flow from the interior of said drum out to the exterior thereof, an outlet or exhaust conduit (4) that removes the drying air from the interior of said drum through said outflow opening, a motor (7) adapted to rotateably drive said drum in a selective manner, characterised In that It comprises a substantially cylindrical element (20) coaxial with the drum axis and formed by a front wall (21) being a portion of the rear wall (21) of the drum, by a base (22; 22A) placed behind said portion of the rear wall of the drum, and by a lateral cylindrical strip (23) so that said cylindrical element (20) is positioned behind and outside the rear wall of the drum (1) to surround said gaskets (40) for recovering air leakages thereof, said portion of the rear wall (21) being provided with a plurality of through apertures (25) so arranged as to correspond to the positions of elevators (30) arranged inside the drum, wherein said elevators are opened on their respective opposite sides (31,32)to receive and release said recovered air leakages inside the drum.
Clothes drying machine according to claim 1, characterized in that the front portion of said elevators terminates before of reaching the drum front wall (26), so that said elevator front openings (32) directly come out into the inner drum.
Clothes drying machine according to claim 1 or 2, characterized In that the diameter of said lateral cylindrical strip (23) is basically the same size of the drum diameter.
Machine according to claim 3, characterized In that said base of said substantially cylindrical element (20) is carried out by a portion of the back wall (22) of the machine.
Machine according to claim 3, characterized In that said base of said substantially cylindrical element (20) is carried out with a specific wall (22A) separate from said machine back wall (22).
Machine according to any one of claims 1 to 5, wherein said lateral cylindrical strip (23) is separated from said drum rear wall (21) by a ring shaped gap (24) allowing the relative motion without slithering between said base with said lateral cylindrical strip and said rear wall.