CLOTHES DRYER WITH AUTOMATICALLY UNLOADING ROTATIONAL DRUM

Abstract: Tumble drier with automatic unloading comprising a cabinet (10) with dry air stream inlet and outlet, a drum (20) accessible by at least one of its ends, with a perforate revolution wall (21) for receiving laundry to be dried, mounted and rotatorily driven in both directions within the said cabinet (10). A generatrix (24) of the said wall (21) at the lowest area of drum (20) is inclined with respect to the horizontal (H) and blades (23) are extending within the said wall (21) obliquely to any generatrix of the wall (21). When rotating the drum in the drying direction, the said obliquity of blades (21) offsets a trend of the laundry to move according to that slope while when rotating in the opposite direction, the obliquity of blades (23) assists the laundry to move according to the slope, unloading the laundry.

Description: Scope of the invention This invention refers to a tumble dryer having a rotating drum of the kind comprising a cabinet and a drum which can rotate within the said cabinet, designed to receive laundry to be dried. The drum has a perforate revolution wall with longitudinal blades arranged on its internal face means being provided for circulating a hot air stream within the cabinet and through the said perforate walls. The tumble dryer of the invention in addition has means for automatically unloading the drum by reversing its rotating direction with the possibility of loading by a first end of the drum and unloading by a second end thereof. The tumble dryer of the invention is specially useful in laundries having a relatively large capacity such as those installed in hotels and hospitals and other laundries in general. Prior art In the art of the sector tumble dryers of above kind are known in which unloading the laundry is carried out by means of an air stream axially directed towards a drum unloading mouth. An example of the said machines is disclosed in patent US-A-4949477 granted to Passat Maschinenbau GmbH filed on 1 June 1989. However, unloading by axially blowing the air stream has the drawback that together with the dried laundry the blowing air carries a large amount of flock from the laundry. That flock pollutes the air within the working area which may cause a harm to the operators health and a malfunction to other machines. To try to remedy this drawback, complex and expensive filtering systems are required to be installed which in addition require a frequent maintenance service. Also tumble dryers are known in which unloading is carried out by tilting the machine or part of it containing the drum. The utility model ES-A-100993 of Hans F. Arendt, filed on 5 August 1963 discloses a tumble dryer of this kind comprising two superposed bodies hinged to each other by means of a set of hinges. Within the top body a rotating drum is mounted for receiving the laundry to be dried the loading/unloading mouth of which is adjacent and parallel to the said hinged part. At the rear part of the lower body a tilting elevator such as a fluid dynamic cylinder is fastened the stem of which when it is extended upwardly pushes the rear part of the top body emptying down the drum contents through the said loading/unloading mouth. In the lower body there are means for generating a drying air stream which is circulated within the top body and through a perforate wall of the drum. The system for unloading by tilting the machine or part of the machine including the drum has the drawback of being mechanically more complex in addition to require that all the dryer connections, such as wiring, air, steam, gas pipes and the like are flexible to allow that tilting, which means more wear and the likelihood that they break. Another kind of known machines unload the laundry by means of a set of transversal inclined wings, eventually concealable, located within a drum having an horizontal spin axis, the said wings, during the drying cycle are kept out of contact with the laundry to be dried and during the unloading cycle they collaborate to expel the laundry from the drum. In patent US-A-3811202 of Hans F. Arendt, filed on 9 April 1993, a machine of this kind is disclosed in which the said wings are located adjacent to one of the flanks of longitudinal blades having a triangular cross section located on the drum internal wall in a direction parallel to the axis itself, so that when the drum rotates in a drying direction, the wings remain at the rear side of the blades with respect to the direction of onwards motion and therefore with little or none impingement on the laundry which is being rotated while when it rotates in an opposite unloading direction, the wings remain at the front side of the blades directly impinging on the laundry creating because of their inclination an effect of dragging the laundry towards the drum outlet mouth. According to an example of a more evolved embodiment the wings are concealable remaining retracted during a drying cycle and being radially lifted by suitable means during an unloading cycle for cooperating with the drum rotating motion for creating the said dragging effect of the laundry towards a drum unloading mouth. However, in order the system is effective, the wings must deeply impinge which can be aggressive for the laundry. In addition, this system means a significant construction complexity due to the large number of wings which have to be fixed leaning against one of the flanks of the blades. The complexity is even higher when the wings are concealable, in which case the mechanical complexity is added of driving means for moving the said wings between two positions depending on the cycle the machine is operating. A tumble dryer according to the preamble of claim 1 is known from document US-A-4640024. Therefore, the object of this invention is to provide a tumble dryer having a rotating drum with automatic unloading provided with means in order that the said automatic unloading is carried out by reversing the rotating direction of the drum, the construction being simple and without an unloading axial air stream nor a machine or part of the machine tilting be required for emptying down the drum contents. Short description of the invention Above object is achieved, according to this invention by providing a machine which comprises a cabinet having an air inlet and outlet. Within the said cabinet a drum is mounted having a wall in the shape of a perforate revolution surface, designed to receive the laundry to be dried, the said drum being driven by suitable driving means so that it can selectively rotate in both directions about a fixed centre-line, On an internal face of the said perforate wall there are arranged blades extending lengthwise along at least part of the length thereof. A turbine connected to the said air outlet circulates the air within the said cabinet and through the said perforate walls, the said circulating air is heated by suitable heating means. To automatically unload the drum, a generatrix of the said revolution wall is inclined with respect to the horizontal plane when it is in the area having the lowest level of the drum, and the said blades are oblique with respect to any generatrix cutting the said blades, so that when the drum rotates in a first direction or drying direction, the said obliquity of the blades produces a dragging effect which offsets a trend of the laundry to move according to the slope of the drum wall to the area having the lowest level, making that the laundry is kept distributed and rotated within the drum for being dried, while when it rotates in a second opposite or unloading direction, the said dragging effect provided by the obliquity of the blades is added to the said trend of the laundry to move according to the slope of the drum wall, unloading the laundry from it. Tests carried out evidenced that an effective unloading is achieved with a slope of the generatrix at the lowest part of the drum from about 1 degree. On the other hand, with a slope over about 15 degrees the blades lost the capacity to offset the motion effect down the slope. In every case the height, shape and obliquity of the blades shall be in accordance with the drum wall angle of slope at the lowest part. Generally, lower values of the drum wall slope will require lower and less oblique blades. Thus it will be understood that for the slope of the drum generatrix at the lowest level, with respect to an horizontal plane lower values are preferred within the interval of effective values because they allow a smoother shape, that is to say, less aggressive to the laundry, of the blades. A 2 to 5- degree angle is the most preferred. The said generatrix angle of slope can be achieved by means of a drum having a cylindric wall rotating about a fixed inclined centre-line or a drum having a trunco-conical wall rotating about a fixed horizontal or inclined centre-line. It is obvious that the shape of the blades also has a significant importance. The said blades have a substantially triangle-shaped cross section, having a base on the internal face of the perforate wall and a apex which is substantially projecting in a radial way towards the drum axis, blades having a higher apex impinging more than lower blades. In an example of embodiment of the invention, both sides of the said triangular shape extending between the said apex and the ends of the said bottom have different slopes with respect to a radius of the drum passing through the said apex or, which is same thing, the blades have two flanks having different slopes ending in a upper edge. Thus, depending on the drum rotating direction, the effect caused by the said flanks is different, a smaller angle impinging more with respect to the said radius than a larger angle. According to an example of embodiment of the invention, the said blades are curved lengthwise for showing a variable obliquity angle with respect to the drum axis direction, having a larger angle a stronger dragging effect than a smaller angle. The number of blades is also variable. Selecting the shapes and sizes of the blades as well as their number will be done depending on the size and proportions of the drum, the generatrix slope of the drum wall at the lowest part, the rotating speeds, among other factors, for achieving that with a rotation in the drying direction the laundry is distributed in a ways as even as possible in the whole of the drum while with the rotation in the unloading direction, the laundry goes quickly and evenly out of the drum. This arrangement of the inclined drum in combination with the oblique blades is useful as well for a machine provided with a single loading/unloading mouth as for a machine provided with a loading mouth at one end of the drum and an unloading mouth provided at the other opposite end thereof. In the first case, the said single loading/unloading mouth is located at the end of the drum corresponding to the lowest end of the said inclined generatrix of the lowest part of the drum. In the second case, the said loading mouth is located at the end of the drum corresponding to the highest end of the said inclined generatrix while the said unloading mouth is at the opposite end of the drum corresponding to the lowest end of the said generatrix. In some of the said machines provided with a single loading/unloading mouth the drying air stream is in axial direction towards the said mouth which also constitutes a laundry dragging factor in that direction which must be offset by the obliquity of the blades, therefore it has to be borne in mind when drawing them. On the other hand, in some machines provided with cross air stream, the said stream can have a slightly axial component the dragging effect of which can also be offset by the blades. Short description of the drawings This invention will be best understood with the detailed description below of examples of embodiment of that invention the description of which includes references to the drawings attached in which: Fig. 1 is a schematized view in longitudinal section according to a vertical plane of the laundry drying machine with automatic unloading of this invention. Fig. 1a is a very schematized view at reduced scale, in longitudinal section according to a vertical plane of a variation of the machine drum of Fig. 1; Fig. 2 is a schematized cross section view of the machine of Fig. 1 seen in the direction of the arrow II of Fig. 1; and Fig. 3 is a cross section view of one of the blades, taken by a normal plane of it. Detailed description of the preferred examples of embodiment Referring first to Fig. 1 and 2, the tumble dryer with automatic unloading of this invention comprises a housing 10 having an air inlet 11 and outlet 12. Within the said housing 10 there is a drum 20 having a perforate revolution wall 21 provided for receiving a load of laundry to be dried R. The said drum 20 is mounted so that it can rotate within the said housing 10 about a fixed centre-line 22. For this, the drum 20 is provided, in a conventional way, with external tracks, not shown, which are supported on several supporting wheels 16 and guiding the rotating motion and is driven by a motor 13 connected by means of a drive 14 to a friction traction wheel 15 which is supported on one of the said annular tracks rotatorily dragging drum 20. On an internal face of the said perforate wall 21 of drum 20 blades 23 are arranged which extend lengthwise along at least part of the said wall 21 length. Although the figures show four of the said blades 23 in drum 20, the number of them is variable according to the conveniences of the drawing, at least one being necessary. A turbine 16 driven by a motor 17 is connected to the said air outlet 12, in order to circulate a drying air stream indicated by arrows A in Fig. 2, within the said housing 10 and through the said perforate wall 21. Heating means 18, such as a steam battery, heat the air of the drying stream A just before the said inlet 11. The machine is drawn in such a way that a generatrix 24 of the said revolution wall 21 is inclined with respect to an horizontal plane, for example, a plane of the floor H, when it is at the area of the drum having the lowest level and the said blades 23 are oblique with respect to any generatrix of the said revolution wall 21 which cuts the said blade 23, so that, when the drum is rotating in a first direction, or drying direction indicated by an arrow S in Fig. 2, a dragging effect provided by the said obliquity of the blades 23 offsets a trend of the laundry to move according to the slope of the said generatrix 24 in the area of the drum lowest level, making that the laundry R is kept rotating, distributed lengthwise within drum 20, for drying it, while when rotating in a second opposite direction or unloading direction indicated by an arrow D in Fig. 2, the said dragging effect provided by the obliquity of blades 23 is added to the said trend of laundry R to be moved according to the slope of generatrix 24 located at the area having the lowest level, unloading the laundry R from drum 20. Although the said slope of generatrix 24 is achieved by means of a drum 20 having a cylindric wall 21 rotating about an inclined fixed centre-line 22 as illustrated in the example of embodiment of Fig. 1, an analogous effect can be achieved with a drum 40 having a trunco-conical wall 41 rotating about an horizontal fixed centre-line 42 as in the example of embodiment illustrated in Fig. 4a or inclined, the said drum also showing a generatrix 44 at the low part of the drum inclined with respect to the horizontal plane H. The drum 40 has also available oblique blades 43, in a way analogous to that explained with relation to drum 20 of Fig. 1 and 2. As explained above, a suitable value for an angle α having a slope of the generatrix 24, 44 of the drum at the lower level with respect to an horizontal plane H is over 1 degree, preferably 2 to 5 degrees, although higher values are also possible for the said angle α, up to 15 degrees , provided that they are offset with sharper slopes of blades 23, 43. On its hand, an angle β of obliquity of blades 23, 43, with respect to any generatrix of the drum wall cutting the said blade 23, 43 (generatrix being a projection of centre-line 22, 42 in Fig. 1 and 2, respectively) has a value of 5 to 30 degrees, depending on factors such as the value of angle α, a profile of the cross section of blades 23, 43, the number of these later, the drum rotating speeds, the existence of axial components in air stream A, among others. Fig. 3 illustrates the said profile of the cross section of blades 23 of the drum of Fig. 1 and 2 (which is also valid for blades 43 of Fig. 1a). The shape of the said profile is substantially triangular, with a base 25 leaning against an internal face of the perforate wall 21 and a apex 26 which is projected in a substantially radial way towards the drum axis. In order to cause a different effect according to the drum rotating direction, the two free sides 27, 28 having the said triangular shape which are extending between the said apex 26 and the ends of the said base 25, have different slopes with respect to a radius Ra of the drum passing through apex 26. Thus, when drum 20 rotates, for example in drying direction, stated by arrows S of Fig. 3, the blade 23 shows a front flank formed by side 27 having a relatively slight slope, producing a slighter dragging effect than when drum 20 is rotating in unloading direction indicated by arrow D, in which case the front flank of blade 23 corresponds to side 28 having a sharper slope, producing a stronger dragging effect. According to the requirements of the drawing the sharper slope can also be located at the front side of the blade when this later is rotating in the drying direction, or even the slope of each side 27, 28 can be variable along blade 23 length for producing a different dragging effect at each area of drum 20 in order to achieve a more even distribution of laundry R in the drum during the drying cycle. With an analogous purpose the said blades 23 can also be provided with a lengthwise curved path (not shown) for showing an obliquity of angle β variable with respect to the direction of a drum generatrix. According to an example of embodiment not illustrated of the tumble dryer of this invention, the drum is provided with a single loading/unloading mouth at one end corresponding to the lowest end of the said generatrix at the area of the drum having the lowest level. According to another example of embodiment of the tumble dryer of this invention illustrated in Fig. 1, 1a and 2, drum 20, 40 is provided with a loading mouth 30 at a first end of the drum corresponding to the highest end of the said inclined generatrix 24, 44 thereof, and an unloading mouth 32 at the other opposite end corresponding to the lowest end of the said inclined generatrix 24, 44 of the lowest part of drum 20.

Claims: Tumble dryer having an automatically unloading rotating drum of the kind comprising: a housing (10) having an air inlet (11) and an air outlet (12); a drum (20) having a perforate revolution wall (21) provided for receiving laundry to be dried (R), said drum (20) being mounted so that it can rotate within said housing (10) about a fixed centre-line (22) and is accessible through at least one of its ends, a generatrix (24) of said revolution wall (21) being inclined with respect to a horizontal plane (H) when it is at the area of the drum (20) having the lowest level; blades (23) arranged on an internal face of said perforate wall (21) extending lengthwise along at least one part of the surface thereof; driving means (13, 14,15) connected to said drum (20) to make it selectively rotate in both directions; a turbine (16) connected to said air outlet (12) to circulate a drying air stream (A) within said housing (10) through said perforate wall (21); and heating means (18) for heating said drying air stream (A), characterized in that : said blades (23) are oblique and form a 5 to 30 degree angle (β) with respect to any generatrix of said revolution wall (21) cutting said blades (23); said blades (23) have a substantially triangular-shaped cross section with a base (25) on the internal face of said perforate revolution wall and an apex (26) which projects in a substantially radial way towards the drum axis; and two sides (27, 28) of the triangular-shaped cross section extending between said apex (26) and the ends of said base (25) have different slopes with respect to a radius (Ra) of drum (20) passing by apex (26) for causing a different effect according to the drum rotating direction, so that, when drum (20) rotates in a first direction, or drying direction (S), a dragging effect provided by said obliquity of blades (23) offsets a trend of laundry (R) to move according to the slope of said generatrix (24) at the area of the drum having the lowest level, making that laundry (R) is kept rotating, distributed lengthwise within the drum (10), for being dried, while when drum (20) is rotating in a second opposite direction, or unloading direction (D) said dragging effect provided by the obliquity of blades (23) is added to that trend of laundry (R) to move according to generatrix (24) slope at the area of lowest level, unloading laundry (R) through a face of one end at a lowest level the drum (20), being the at least one accessible end of the drum at the lowest end of said generatrix (24). Tumble drier according to claim 1, characterized in that said generatrix (24) located at the area of drum (10) having the lowest level forms an angle (α) over 1 degree with respect to horizontal plane (H). Tumble drier according to claim 1, characterized in that the slope of each of said sides (27, 28) is variable along blade (23) length for producing a different dragging effect at each area of drum (20). Tumble drier, according to claim 1, characterized in that said blades (23) are curved lengthwise for showing an obliquity angle (β) variable with respect to any generatrix of wall (21) cutting them. Tumble drier according to claim 1, characterized in that said perforate wall (21) of drum (20) is cylindrical, said drum fixed centre-line 22 being inclined with respect to an horizontal plane (H). Tumble drier, according to claim 1, characterized in that said perforate wall (41) of drum (40) is frustum-conical, said fixed centre-line (42) of drum (40) being horizontal or inclined with respect to an horizontal plane (H). Tumble drier, according to any one of preceding claims, characterized in that said drum (20) has a loading mouth (30) at a first end corresponding to the highest end of said generatrix (24) located at the area of the-drum having the lowest level and an unloading mouth (32) at a second end corresponding to the lowest end of said generatrix (24) at the lowest level of the drum. Tumble drier, according to any of claims 1 to 6, characterized in that said drum (20) has a loading/unloading mouth at one end corresponding to the lowest end of said generatrix (24) at the area of the drum having the lowest level.

Inventors: ARCARONS ALIBES DANIEL, GIRBAU POUS PERE, SANS ROVIRA RAMON, ARCARONS ALIBES, DANIEL, GIRBAU POUS, PERE, SANS ROVIRA, RAMON
Applicants: GIRBAU SA, GIRBAU, S.A.
Application year: 2000
Main classification: D06F58
IPC codes: D06F58, D06F95