EP1916327B1

EP1916327B1 - Tumble dryer

Info

Publication number: EP1916327B1
Application number: EP06122612A
Authority: EP
Inventors: Elisabetta Bari; Alberto Bison; Giancarlo Gerolin; Marco Clara
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2006-10-19
Filing date: 2006-10-19
Publication date: 2011-03-23
Anticipated expiration: 2026-10-19
Also published as: DE602006020879D1; RU2007138842A; PL1916327T3; ATE503052T1; RU2452803C2; ES2363789T3; EP1916327A1

Abstract

Tumble dryer including a rotating drum (2) mounted within an outer casing and adapted to receive articles to be dried, said drum (2) comprising a cylindrical side wall (3), a front flange (11) with a clothes access openingh, and a rear flange (5), it comprises at least a sound-damping covering (8) associated to the external surface of the drum (2) for absorbing the sound wave produced by the articles being tumbled inside said drum (2) and impinging against the wall thereof during dryer operation, said sound-damping covering (8) including a metal sheet (9) and an adhesive layer (10) interposed between the sheet (9) and the external surface of the drum (2).

Description

The present invention relates to a tumble dryer having improved soundproofing characteristics.
Household clothes drying machines typically comprise a sheet-steel rotating drum, in which clothes are tumbled as hot air is circulated therethrough to remove moisture from and dry the clothes. As the clothes tumble within the dryer drum, they keep falling against the wall of the drum wall, wherein heavier clothing items, as well as buttons, zippers and other metal or, anyway, hard ornaments that may be associated with the clothes being dried or hanging loose thereamong (e.g. coins) have a tendency to strike against the dryer drum wall and generate noise in the course of the drying process. Furthermore, the drum works in this case as a resonant chamber, so that the level of the thus generated noise is eventually boosted.
A need is therefore felt for the noise generated by clothes and other items tumbling within the dryer drum to be suitably reduced.
As a result, in view of solving this problem, the drum is usually designed to feature an increased wall thickness. This however means also a corresponding increase in the overall weight of the drum, thereby making it certainly more difficult to perform the assembly process. In addition, providing the drum with a greater thickness of its walls causes manufacturing costs to increase accordingly.
To compensate for or reduce the noise generated by the clothes and items being tumbled in the dryer drum, a possible known solution lies in the use of sheets of plastic foam to line the inner surface of the peripheral wall of the dryer drum as a soundproofing means. The problem with these dryers, however, is that the foamed plastic selected for the application shall be such as to properly withstand the certainly high temperatures, which it will be exposed to during drying; furthermore, it may be difficult to assemble such material inside the drum, whereby the final cost of the dryer would ultimately be affected resulting in a higher selling price.
In another attempt to reduce the noise generated by the articles tumbling within a clothes dryer, use is made of a rotating dryer drum having walls made of multi-layer sheet-metal featuring a plastic material sandwiched between metal sheets. While this solution does not involve the use of a foamed-plastic sheet to be attached so as to line the inside surface of the dryer drum wall, the use of a laminated dryer drum wall, comprising two sheet-steel plates having to be bonded together through the interposition of a resin material sandwiched therebetween, does anyway imply a drum structure that is rather complicated to manufacture, under an unavoidable increase in manufacturing costs and, ultimately, in the selling price of the clothes dryer.
Document EP-A-1541741 discloses a tumble dryer with sound damping covering according to the preamble of claim 1.
Accordingly, there is a need for a clothes dryer with enhanced soundproofing characteristics to be provided, which will on the other hand not require any significant departure from existing dryer drum constructions, thereby adding to a relatively small extent to the overall manufacturing costs of the clothes dryer.
Accordingly, the present invention is directed to a laundry dryer that substantially obviates the problems arising from typical limitations and disadvantages of prior-art machines in this connection.
It is therefore an object of the present invention to provide a laundry dryer having a structure that can prevent vibration and noise from being incurred in the drum.
According to the present invention, this aim, along with further ones that will become apparent from the following disclosure, is reached in a clothes dryer incorporating the features as defined and recited in the claims appended hereto.
Features and advantages of the present invention will anyway be more readily understood from the description that is given below by way of nonlimiting example with reference to the accompanying drawings, in which:

Figure 1 is a front-elevational perspective view of the drum of a tumble dryer according to the present invention;
Figure 2 is a rear-elevational perspective view of the drum of a tumble dryer according to the present invention.

The tumble dryer is provided with an outer casing adapted to allow the control panel of the machine to be mounted thereon, as well as a rotating drum 2 to be accommodated therein along with motor and blower means.
Such outer casing has a front wall provided with a door enabling the user to gain access to the interior of the drum through an access opening. The drum 2 is mounted inside this casing for rotation about its central axis, as driven by a motor arranged to drive the drum by means of a belt.
Within said outer casing, the drum 2 is also arranged so as to be located in an air flowpath, thereby enabling dry heated air to be forced therethrough to remove moisture from the clothes being tumbled therein.
The drum 2 is comprised of a cylindrical side wall 3 made of metal, in particular stainless steel, on the inner surface of which there are applied so-called lifters 4, specially provided to assist the clothes in being properly tumbled, a front flange 11 with a clothes access opening and a rear flange 5, both made of metal.
The drum is made in a single-piece unitary construction and the rear flange is mechanically connected to a shaft 6 about which the drum 2 is adapted to rotate.
In a central portion of the rear flange 5, around the rotating shaft 6, there are provided a plurality of holes 7 for the drying air to be able to pass therethrough.
In an alternative embodiment the drum can be comprised of a cylindrical side wall 3 rotatably fitted to a front flange 11 and a rear flange 5, which are stationary relative to the outer cabinet and the cylindrical side wall 3. There are sealing members fitted between the front flange 11 and the cylindrical side wall 3, and the rear flange 5 and the cylindrical side wall 3, both make relative motion, for preventing of leakage. The rear flange 5 is fitted with air supply means in communication with the inside of the drum 2 for supplying a heated air flow to the inside of the drum 2.
In an advantageous manner, the tumble dryer comprises at least a sound-damping covering 8 associated to the external surface of the drum 2 for absorbing the sound waves generating from the impingement noise of the articles that are tumbled inside the drum during dryer operation, wherein said sound-damping covering 8 includes a metal sheet 9 and an adhesive layer 10 interposed between the sheet 9 and the external surface of the drum 2.
The sound waves that are generated by the pulse-like occurrences deriving from the clothes, and in particular the hard or metal items associated thereto, such as for instance buttons or zippers, impinging against the inner surface of the metal wall of the rotating drum 2 are for the most part absorbed by the adhesive layer 10 which, by the effect of its viscoelastic properties, substantially converts these sound waves and vibrations into heat, thereby heating up the adhesive layer 10.
On the other hand, the sound waves that succeed in passing through and issuing from the glue layer 10 are transmitted to the metal sheet 9, where they undergo further damping.
The sound-damping covering 8 created by the adhesive layer 10 and the metal sheet 9 forms a system that is able to damp and absorb sound waves propagating within a given frequency range, which depends on the characteristics of the adhesive layer 10 and the metal sheet 9.
In particular, it has been found that an adhesive layer having a thickness ranging from 100 to 300 µm and a surface density ranging from 50g/m² to 150g/m², proves particularly effective in absorbing sound waves with a frequency lying within a range of 500 to 10000 Hz, which are typical frequencies of the noise generated by clothes impinging against the walls of the drum 2. It has on the other hand been found that a metal sheet 9 having a thickness ranging from 150 to 300 µm optimally combines with an adhesive layer 10 having the characteristics as indicated above.
It has in practice been found that the more the thicknesses of the drum wall (cylindrical side wall 3, front flange 11, and rear flange 5) and the metal sheet 9 are similar to each other, if not preferably equal to each other, the more effective are the sound-wave damping and absorption characteristics thereof.
It has furthermore been found that the effectiveness in absorbing the sound waves is the greatest one when use is made of a metal sheet 9 that is made of the same metal material as the drum 2. For instance, in the case of a drum 2 made of stainless steel, a metal sheet 9 that is itself made of stainless steel would ensure the best sound-wave absorption performance.
An adhesive layer 10 formed of silicone-based or acrylic glue has proven particularly effective thanks to both the viscoelastic properties thereof and the fact that such glues can be used in a temperature range from -40°C to 180°C while keeping their sound-wave absorption and damping characteristics unaltered in the long term notwithstanding the temperature variations, which they are subject to during drying processes.
In addition, such glues prove as being particularly effective when working at the typical temperatures reached by the walls 3,5 of the drum 2 during the drying cycles and also in case of overheating due to operation irregularity or failure.
Moreover, the adhesive layer 10 enables the metal sheet 9 to be attached to the drum 2 in a quick manner, without any use of fastening means whatsoever, such as screws or the like, being required, actually.
In a particularly advantageous embodiment, which is illustrated in Figure 1, the drum 2 is clad with a plurality of sound-damping covering members 8 that substantially cover most of the external cylindrical surface of the drum 2, so as to be able to maximize the sound-wave absorption effect. The adhesive layer 10 is preliminarily applied to the surface of the metal sheet 9 that is due to be associated to the external surface of the drum 2. Then, the metal sheet 9 is glued onto the external cylindrical surface of the drum 2.
Alternatively, the sound-damping covering 8 may be comprised of a single member that is wrapped around and applied on to the external cylindrical surface of the drum 2 along the entire circumference thereof, so as to almost entirely cover such surface.
In a highly preferred manner, according to the invention, further to the external cylindrical surface of the drum 2, the sound-damping covering 8 is also associated to the external surface of the front flange 11 and the rear flange 5 of the same drum 2, as shown in figure 1 and 2, wherein said sound-damping covering 8 may even in this case be provided in the form of either a single piece or a plurality of sound-damping coverings 8 applied to said front and rear flange 11,5.
In a particular embodiment of the present invention, the cylindrical side wall 3 of the drum 2 is made of a polymer material, whereas the rear flange 5, connected to the rotating shaft 6, is made of metal material, in particular stainless steel, and the sound-damping covering 8 is solely associated to said rear flange 5 and not to the cylindrical side wall 3. Expediently the sound-damping covering 8 can also be provided on the front flange 11.
Conclusively, it can therefore be stated that the tumble dryer according to the present invention effectively reaches its basic aim by providing a tumble dryer having a drum with improved sound-damping characteristics.
The sound-damping covering according to the present invention, further to being most effective in absorbing and damping sound waves generating from the clothes and associated items impinging against the inner wall of the drum, is very simple to manufacture and attach to the drum, thereby doing away with the drawback usually shared by prior-art machines.

Claims

Tumble dryer including a rotating drum (2) mounted within an outer casing and adapted to receive articles to be dried, said drum (2) comprising a cylindrical side wall (3), a front flange (11) with a clothes access opening, and a rear flange (5), and at least a sound-damping covering (8) associated to the external surface of the drum (2) for absorbing the sound wave produced by the articles being tumbled inside said drum (2) and impinging against the wall thereof during dryer operation, said sound-damping covering (8) including a metal sheet (9) and an adhesive layer (10) interposed between the sheet (9) and the external surface of the drum (2), characterized in that one or more of said sound-damping covering (8) are solely associated to the external surface of the rear flange (5) and/or the front flange (11) of the drum (2).
Dryer according to claim 1, wherein the cylindrical side wall (3) of the drum (2) is made of a polymer material, whereas the rear flange (5) is made of metal material, and the sound-damping covering (8) is associated to the external surface of said rear flange (5).
Dryer according to claim 1 or 2, wherein said adhesive layer (10) has a thickness ranging from 100 to 300 µm.
Dryer according to claim 3, wherein said adhesive layer (10) has a surface density in the range from 50g/m² to 150g/m².
Dryer according to claim 4, wherein said metal sheet (9) has a thickness in the range from 150 to 300 µm.
Dryer according to claim 4, wherein said metal sheet (9) has the same thickness as the walls (3, 5, 11) of the drum (2),
Dryer according to any of the preceding claims, wherein said metal sheet (9) and said drum (2) are made of the same metal material.
Dryer according to any of the preceding claims, wherein said adhesive layer (10) is comprised of a silicone-based and/or acrylic glue.