Roller structure for roller dryer and roller dryer

Abstract

The invention discloses a roller structure for a roller dryer and the roller dryer. A drum structure includes: a pivoting sidewall made of plastic material, in a tubular shape, and having an annular rear edge defining a rear opening and an annular front edge defining a front opening; a stationary rear wall forming an annular receptacle pivotally engaging a rear edge of the side wall about the axis of rotation and such that the stationary rear wall closes the rear opening of the pivot side wall, and a perforation allowing a drying airflow to pass through the stationary rear wall in the laundry compartment defined by the pivot side wall and the stationary rear wall; a plurality of rear support rollers and a plurality of front support rollers pivotally support the side wall about a rotational axis relative to the stationary rear wall.

Description

Technical Field

[0001] The present invention relates to a drum structure for a drum dryer and to a drum dryer, in particular a domestic drum dryer, which provides drying of laundry contained in a laundry drum by rotating the laundry drum and generating a drying air flow through the laundry drum. Background Art

[0002] In a closed drying circuit using an electric resistor or a heat pump, hot, dry air is pumped into the laundry drum, where it passes through the wet laundry, causing the water contained in the fabrics to evaporate. After leaving the laundry drum, the moisture-laden dry air passes through a heat exchanger, where it is cooled to extract moisture through condensation. The dehumidified dry air is then drawn in again by a fan, heated, and directed back into the laundry drum.

[0003] Drum dryers are known in which a laundry drum comprises a rear wall (sometimes called a rear flange) perforated to allow the entry of drying air, circumferential side walls (typically non-perforated) and a front edge or annular front wall defining a front opening of the laundry drum for inserting and removing laundry from the laundry drum and for removing the drying air flow from the laundry drum after passing through and grinding the laundry, absorbing moisture therefrom. The rear, side and front walls of the drum together form a substantially rigid hollow body having the geometry of a solid of revolution.

[0004] It is also known to pivotally support the laundry drum around an axis of rotation, which is typically the center axis of the geometry of the laundry drum. The pivotal support can be cantilevered by means of a drive hub rigidly connected to the rear wall of the laundry drum and by placing the laundry drum on a plurality of support rollers on the front side of the laundry drum.

[0005] In order to rotate the drum about the axis of rotation, it is known to provide an electric motor with a transmission, for example a belt transmission between the electric motor and the drive hub or between the electric motor and the side wall of the laundry drum, alternatively, the rotor of the electric motor is directly coupled to the rear wall of the laundry drum in order to transmit the rotational movement to the rear wall of the laundry drum.

[0006] It is known to manufacture a laundry drum from stainless steel sheets and it has also been proposed for at least a portion of the laundry drum to be manufactured from plastic material.

[0007] As an alternative to the conventional concept of a rigid pivoting drum, it has also been proposed to create a laundry compartment using flexible strip-like side walls that are guided and moved along a closed, non-circular path, thereby defining a space for receiving and moving the laundry itself. In this case, the rear and front walls that define the laundry compartment do not move together with the strip-like side walls.

[0008] Due to the arrangement of the drying circuit components, typically radially outside and in the center or laterally below the laundry drum, the ventilation duct guiding the drying airflow to the perforated rear wall extends from the radial outside of the laundry drum along the rear side of the laundry drum, parallel to the rear wall, and axially toward the interior opening of the laundry drum.

[0009] The resulting air path is oriented perpendicular to the laundry drum's axis of rotation before being redirected 90° through perforations in the rear wall of the laundry drum. This results in uneven drying airflow upon entering the laundry drum. In particular, the accumulated air pressure (and therefore the inlet air velocity) is greater in the area at the bottom of the ventilation duct than in areas further upstream.

[0010] Furthermore, the rotation of the laundry drum and its rear wall creates a radial fan effect on the airflow, redirecting part of it radially outwards, whereas ideally the laundry to be dried should rotate inside the laundry drum and be ground and traversed by an airflow that is as axial and uniform as possible.

[0011] Furthermore, the rotating rear wall, which is traversed by the airflow, is a source of unwanted noise.

[0012] Washing drums made of steel sheets (galvanized or stainless steel), manufactured by a pressing operation, mechanical expansion and joining the parts by bending the edges, are undesirably heavy, require expensive raw materials of uncertain supply and a complex and expensive manufacturing process.

[0013] Plastic laundry drums made by injection molding and subsequent bonding of components by gluing and ultrasonic welding are made of cheaper and lighter materials. However, bonding of multiple components (side walls and perforated rear wall) that are made separately by injection molding means undesirable manufacturing costs and complexity.

[0014] An object of the present invention is therefore to provide a laundry drum structure for a tumble dryer and a tumble dryer having features such as to overcome at least some of the disadvantages of the prior art.

[0015] The specific objects of the present invention are:

[0016] - increase the constructional simplicity of the laundry drum structure and reduce the number of individual parts to be joined together by welding, gluing and edge bending,

[0017] - Reduce the risk of corrosion of the laundry drum structure and ventilation ducts,

[0018] - Reduce the uncertainty of steel plate supply,

[0019] - Reduce the manufacturing cost of the laundry drum structure,

[0020] - Increase the energy performance of the tumble dryer by improving the inlet flow conditions into the laundry drum,

[0021] - Increased possibility to influence and design the inlet flow conditions through the rear wall into the laundry drum,

[0022] -Reduces noise from the drum structure and tumble dryer during operation. Summary of the Invention

[0023] These and other objects are achieved by a laundry drum structure for a tumble dryer type comprising a laundry compartment for receiving laundry to be dried and a drying circuit for conveying a drying air flow through the laundry compartment, wherein the drum structure comprises:

[0024] a pivoting side wall made of plastic material, extending circumferentially around an axis of rotation (which also constitutes the central axis of the side wall) and having an annular rear edge delimiting a rear opening, and an annular front edge delimiting a front opening,

[0025] - a stationary rear wall, which is transverse to the axis of rotation and forms:

[0026] a) an annular receptacle that pivotally engages the rear edge of the side wall about an axis of rotation and causes the stationary rear wall to close the rear opening of the pivoting side wall, and

[0027] b) perforations for allowing a drying air flow through the stationary rear wall in the laundry compartment defined by the pivoting side walls and the stationary rear wall,

[0028] - a plurality of rear support rollers pivotally supported by the stationary rear support portion, and a plurality of front support rollers pivotally supported by the stationary front support portion,

[0029] The side walls are formed with rear support rails resting on rear support rollers and front support rails resting on front support rollers for pivotally supporting the side walls relative to the stationary rear wall and relative to the rear and front support portions about a rotation axis.

[0030] Due to the material separation of the side walls and the rear wall, the plastic side walls can be manufactured using a single injection molding or blow molding process without the need for additional bonding, gluing or welding of components, which significantly simplifies manufacturing and reduces the cost of the drum structure.

[0031] Due to the cooperation and combination of the pivoting side walls and the stationary rear wall, the perforations for introducing drying air into the clothing compartment remain stationary, which eliminates the radial fan effect, reduces noise and allows the perforation openings to be configured and distributed with the purpose of guiding the airflow and distributing the flow rate as required.

[0032] Due to the relative movement between the stationary rear wall and the pivoting side walls, the tendency of parts of the laundry to remain stationary in the corners between the side and rear walls is also reduced and creates another component of movement of the laundry inside the laundry compartment and opening of the clothing items.

[0033] Due to the provision of two different support rails, a front support rail and a rear support rail, and two sets of support rollers, a front support roller and a rear support roller, the present invention eliminates the need to provide a cantilever support for the laundry drum (meaning the set of rear and side walls) via a support shaft or hub and relative fasteners and reinforcements to the rear wall. The absence of these components (present in prior art embodiments) also allows the perforated opening to be provided also in the central area of ​​the rear wall (which would otherwise be occupied). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to better understand the present invention and appreciate its advantages, some non-limiting embodiments will be described below with reference to the accompanying drawings, in which:

[0035] Figure 1 is a diagrammatic side view according to a vertical cross-sectional plane of a drum dryer showing the drying airflow and drum structure according to an embodiment of the present invention;

[0036] Figure 2 is based on Figure 1 A diagrammatic top view of a horizontal cross-sectional plane of a drum dryer in FIG, showing the drying air flow (continuous arrows) and the cooling air flow (dashed arrows);

[0037] Figure 3 is a cross-sectional view of a drum structure for a drum dryer according to an embodiment;

[0038] Figure 4 shows a side wall of a drum structure in a cross-sectional view according to a radial cross-sectional plane according to an embodiment;

[0039] Figure 5 shows a cross-sectional view of a side wall of a drum structure according to an embodiment with the cross-sectional plane being orthogonal to the axis of rotation of the side wall;

[0040] Figure 6 is a front view of the rear wall and rear cover of the drum structure according to an embodiment,

[0041] Figure 7 shows details of the front gasket of the drum structure according to an embodiment,

[0042] Figure 8 is a diagrammatic view of a closed drying circuit of a tumble dryer with a heat pump according to the present invention,

[0043] Figure 9 is a diagrammatic view of a closed drying circuit of a tumble dryer with a resistor according to the invention. DETAILED DESCRIPTION

[0044] Referring to the accompanying drawings, the drum dryer 1 includes a housing 2 (which houses a laundry compartment 3 defined by a drum structure 4 for accommodating laundry to be dried), a motor 5 for moving the laundry in the laundry compartment 3, and a drying circuit 6 which conveys a drying air flow 15 through the laundry compartment 3.

[0045] The drum structure 4 includes:

[0046] a pivoting side wall 7 made of plastic material, extending circumferentially (but not necessarily precisely circular) relative to an axis of rotation 8 (which also constitutes the central axis of the side wall 7 ) and having an annular rear edge 9 delimiting a rear opening 10 , and an annular front edge 11 delimiting a front opening 12 ,

[0047] - a stationary rear wall 13 , which is transverse or orthogonal to the axis of rotation 8 and forms:

[0048] a) an annular receptacle 14 which pivotally engages the rear edge 9 of the side wall 7 about the axis of rotation 8 and causes the stationary rear wall 13 to close the rear opening 10 of the pivoting side wall 7, and

[0049] b) perforations 22 for allowing a drying air flow 15 to pass through the stationary rear wall 13 in the laundry compartment 3 delimited by the pivoting side wall 7 and the stationary rear wall 13,

[0050] - a plurality of rear support rollers 16 pivotally supported by a stationary rear support portion 17, and a plurality of front support rollers 18 pivotally supported by a stationary front support portion 19,

[0051] The side wall 7 forms a rear support rail 20 placed on the rear support roller 16 and a front support rail 21 placed on the front support roller 18, so as to pivotally support the side wall 7 around the rotation axis 8 relative to the stationary rear wall 13 and relative to the rear stationary support part 17 and the front stationary support part 19.

[0052] Due to the material separation of the side wall 7 and the rear wall 13 , the plastic side wall 7 can be manufactured using a single injection molding or blow molding process without the need for additional bonding, gluing or welding of components, which significantly simplifies manufacturing and reduces the cost of the drum structure 4 .

[0053] Due to the cooperation and combination of the pivoting side wall 7 and the stationary rear wall 13, which together form a laundry drum, the perforations 22 for entering the drying air 15 into the laundry compartment 3 remain stationary, which eliminates the radial fan effect and reduces noise and allows the perforated openings 22 to be configured and distributed, the purpose of which is to guide the air flow 15 and distribute the flow rate as required.

[0054] Due to the relative movement between the stationary rear wall 13 and the pivoting side walls 7, the tendency of parts of the laundry to remain stationary in the corner between the side walls 7 and the rear wall 13 is also reduced and creates another component of movement of the laundry inside the laundry compartment 3 and opening of the clothing items.

[0055] Due to the provision of two different support rails, a front support rail 21 and a rear support rail 20, and two sets of support rollers, a front support roller 18 and a rear support roller 16, the present invention eliminates the need to provide a cantilever support for the laundry drum (meaning the set of rear wall 13 and side walls 7) via support shafts or hubs and relative fasteners and reinforcements to the rear wall. The absence of these components (present in prior art embodiments) also allows the perforated opening 22 to be provided even in the central area of ​​the rear wall 13 (which would otherwise be occupied).

[0056] Detailed description of rear wall 13

[0057] According to one embodiment, the rear wall 13 is made of a plastic material, advantageously a fiber-reinforced plastic material, and is preferably formed by injection molding. This further reduces the material and manufacturing costs of the drum structure 4, allowing the rear wall to be manufactured, for example, by a single injection molding process, during which the perforated openings 22 are also made without wasting material and without requiring any shearing or punching processes, as well as the annular receptacle 14.

[0058] The rear wall 13 comprises a circular bottom portion 23 , for example concave or substantially flat towards the interior of the laundry compartment 3 , delimited by the annular receptacle 14 and in which the entire perforation 22 is formed.

[0059] The bottom portion 23 is imaginarily divided by a first horizontal diameter 24 and a second vertical diameter 25 (the first horizontal diameter 24 and the second vertical diameter 25 being perpendicular to each other and radial with respect to the axis of rotation 8):

[0060] - a first upper left quadrant 26_1 (seen from the inside of the laundry compartment 3),

[0061] - a second upper right quadrant 26_2 (seen from the inside of the laundry compartment 3),

[0062] - a third lower left quadrant 26_3 (seen from the inside of the laundry compartment 3),

[0063] - fourth lower right quadrant 26_4 (seen from the inside of the laundry compartment 3).

[0064] According to an embodiment, the total "upper" opening area of ​​the perforations 22 in the first quadrant 26_1 and the second quadrant 26_2 put together is smaller than the total "lower" opening area of ​​the perforations 22 in the third quadrant 26_3 and the fourth quadrant 26_4 put together, in particular when the drying air 15 in the drying circuit 6 is transported upward from the bottom of the side wall 7 to the rear wall 13.

[0065] Optionally, the total "upper" opening area of ​​the perforations 22 in the first quadrant 26_1 and the second quadrant 26_2 put together is larger than the total "lower" opening area of ​​the perforations 22 in the third quadrant 26_3 and the fourth quadrant 26_4 put together, particularly when the drying air 15 in the drying circuit 6 is transported downward from above the side wall 7 to the rear wall 13.

[0066] This makes it possible to compensate for the influence of the arrival direction of the air flow 15 upward to the rear wall 13 and to make the air flow 15 uniform within the laundry compartment 3 .

[0067] Similarly, according to an embodiment, the total “left” opening area of ​​the perforations 22 in the first quadrant 26_1 and the third quadrant 26_3 taken together is smaller than the total “right” opening area of ​​the perforations 22 in the second quadrant 26_2 and the fourth quadrant 26_4 taken together, in particular when the drying air 15 in the drying circuit 6 is delivered from the right side of the side wall 7 to the left (again seen from the inside of the laundry compartment 3) to the rear wall 13.

[0068] Alternatively, according to an embodiment, the total “left” opening area of ​​the perforations 22 put together in the first quadrant 26_1 and the third quadrant 26_3 is larger than the total “right” opening area of ​​the perforations 22 put together in the second quadrant 26_2 and the fourth quadrant 26_4, in particular when the drying air 15 in the drying circuit 6 is delivered from the left side of the side wall 7 to the right (seen from the inside of the clothing compartment 3) to the rear wall 13.

[0069] According to an embodiment, the annular receptacle 14 comprises an annular groove 27 facing the annular rear edge 9 and forming and housing a front gasket 28 in sliding contact (with low friction) with the rear annular edge 9. The front gasket 28 has the function of sealing the rotational coupling of the air circuit composed of the side wall 7 and the stationary wall 13, and may comprise an elastically flexible base (for generating an elastic contact preload and compensating for geometric tolerances) fastened to the stationary wall 13 and supporting the sealing gasket, in frontal contact with the side wall 7 and made of a low-friction material, such as wool felt or synthetic fibers.

[0070] The annular groove 27 is delimited by two walls 29 , is flanked by the rear annular edge 9 , and stabilizes its circular shape in the event of unwanted deformations due to uneven and unbalanced loading of the laundry.

[0071] According to the embodiment, the rear support portion 17 is directly formed by the rear wall 13 and, therefore, the rear support rollers 16 are directly supported by the rear wall 13. The rear support rollers 16 include two rollers arranged in the same rear support plane 30 orthogonal to the rotation axis 8, and the two rollers are in symmetrical lower positions relative to a vertical plane radial to the rotation axis 8.

[0072] According to an embodiment, the drum structure 4 includes a rear cover 31 made of a plastic material, for example a fiber-reinforced plastic material, which is connected to the rear wall 13 on the rear side of the drum structure 4, opposite the side wall 7, and together with the rear wall 13 defines a rear air channel 32 of the drying circuit 6, which is connected to the perforation 22 of the rear wall 13.

[0073] The fact that the rear air channel 32 is made of plastic material further reduces the weight and costs for material and for manufacturing the drum structure 4 , reduces the risk of corrosion and facilitates assembly of components made solely of synthetic materials.

[0074] According to an embodiment, the rear cover 32 can be mounted on the rear wall in the following manner:

[0075] - a form coupling (bayonet or threaded, or by mutual insertion of special coupling guides formed on the rear cover 32 and on the rear wall 13), or

[0076] - an interference fit (e.g. by fastening clips, snap-fits or screws), or

[0077] - gluing or welding, e.g. ultrasonically.

[0078] According to an embodiment, the rear cover 32 is formed integrally with the rear wall by injection molding.

[0079] According to an embodiment, the back cover 32 has:

[0080] a half-shell shape 33 defining an internal cavity intended to face the rear wall 13 , or

[0081] A first tubular portion 34 and a second half-shell portion 33 defining an internal cavity intended to face the rear wall 13 .

[0082] Detailed description of side wall 7

[0083] According to one embodiment, the side wall 7 forms one or more drag paddle members 35 protruding towards the interior of the laundry compartment 3 and formed integrally (eg by injection moulding or blow moulding) with the side wall 7. This reduces the number of separate parts to be assembled and the manufacturing costs.

[0084] The drag paddle or paddles 35 are formed by local recesses of the side wall 7 forming cavities on the radially outer surface of the side wall 7 and corresponding convex protrusions on the radially inner surface of the side wall 7 .

[0085] Advantageously, the drag paddle or paddles 35 do not extend up to the rear edge 9 and do not extend up to the front edge 11 so as not to negatively interfere with the closing function of the laundry compartment 3 on the rear and / or front side of the side wall 7 .

[0086] Further advantageously, one or more drag paddle members 35 extend into the axially extended central region of the side wall 7, between the front support rail 21 and the rear support rail 20, but do not reach the front support rail 21 and the rear support rail 20, so as not to negatively interfere with the rolling of the front support roller 18 and the rear support roller 16.

[0087] According to one embodiment, the drag paddle 35 (and / or the entire inner surface of the side wall 7 in the extension region of the drag paddle 35) has a shape that tapers radially toward the axis of rotation 8 (or has converging draft angles). This allows the side wall 7 to be manufactured particularly quickly and inexpensively by injection molding with the aid of an inner mold that tapers radially toward the inside.

[0088] Likewise, according to an embodiment, the drag paddle (and / or the entire inner surface of the side wall 7 in the extension region of the drag paddle 35) has a shape that widens radially outwards (or has a diverging draft angle). This allows the side wall 7 to be manufactured particularly quickly and inexpensively by injection molding using an outer mold that can be opened / retracted radially toward the outside.

[0089] In this context, it is particularly advantageous if the side wall 7 forms exactly two drag paddle elements 37 in (preferably symmetrical) diametrically opposed positions relative to a central radial plane 36 of the side wall 7. This makes it possible to use only two opposing outer mould "cheeks" which are closable and openable in a direction orthogonal to the central radial plane 36.

[0090] According to an embodiment, the side wall 7 forms a cylindrical pulley seat 37, facing radially outwards and delimited on both sides by two annular parallel ribs 38, for securely receiving a belt 39 for transmitting the rotary motion from the electric motor 5 to the side wall 7. The pulley seat 37 and the two annular parallel ribs 38 are also made of plastic material and are formed integrally with the side wall 7. This reduces the number of individual parts to be assembled and the manufacturing costs.

[0091] According to an alternative embodiment, the side wall 7 may form a ring gear (not shown) adapted to be engaged by gears for transmitting the rotational movement from the electric motor 5 to the side wall 7. The ring gear is also made of plastic material and formed integrally with the side wall 7.

[0092] According to an embodiment, the rear support rail 20 and the front support rail 21 have a cylindrical shape, while the side wall 7 has a non-cylindrical shape, for example a shape having one or more frustoconical segments and / or having one or more steps formed between adjacent frustoconical and / or cylindrical segments.

[0093] The rear support rail 20 and the front support rail 21 have a partial cylindrical shape in the overall non-cylindrical side wall 7, creating thickened material sections and / or having local curvatures or angles, which act as reinforcing ribs of the side wall 7 (compensating for the reduced stiffness of the plastic material relative to the stiffness of the steel plate roller) and can be easily manufactured by injection molding.

[0094] According to an embodiment, the drum structure 4 or the drum dryer 1 comprises a stationary front wall 40 which is transverse or orthogonal to the axis of rotation 8 and forms an annular front receptacle 41 which pivotally engages the front edge 11 of the side wall 7 about the axis of rotation 8 without obstructing the front opening 12 of the pivoting side wall 7.

[0095] According to an embodiment, the front receptacle 41 comprises an annular groove 42 facing the annular rear edge 11 and forming or housing a (further) front gasket 28 in sliding contact (with low friction) with the front annular edge 11. The annular groove 42 is delimited by two walls 43 that flank the rear annular edge 11 and stabilize its circular shape in the event of unwanted deformations due to uneven and unbalanced loading of the laundry.

[0096] According to an embodiment, the front support portion 19 is formed directly by the stationary front wall 40 and, therefore, the front support rollers 18 are supported directly by the front wall 40. The front support rollers 18 comprise two rollers arranged in the same front support plane 44 orthogonal to the rotation axis 8, in symmetrical lower positions relative to a vertical plane radial to the rotation axis 8.

[0097] In a known manner, the front opening 12 is openable and closable by a front door 45 of the tumble dryer 1 .

[0098] Description of Tumble Dryer 1

[0099] The invention described so far can advantageously be implemented in a tumble dryer 1 , for example with a closed air circuit of the resistor or heat pump type.

[0100] In the embodiment in which the closed drying circuit 6 has a resistor ( Figure 9), the dry air 15 is conveyed by means of a fan 46 (actuated by a motor 47), heated by means of an electrical resistor 48 and directed into the laundry compartment 3, where, as it passes through the wet laundry, it causes the water contained in the fabrics to evaporate. After leaving the laundry compartment 3, the moisture-laden dry air 15 passes through a heat exchanger 49, where it is cooled, for example, by means of cold water or a fresh air flow 50 conveyed by a second fan (preferably, but not necessarily, operated by the same electric motor 47), in order to remove moisture from it by condensation. The condensate is collected in a removable condensation container or discharged by a drain pump and / or together with the cooling water. The dehumidified dry air 15 is then sucked in again by the fan 46, heated by means of an electrical resistor 48 and redirected into the laundry compartment 3. A lint filter 51 is arranged upstream of the heat exchanger 49, where the moisture is removed.

[0101] In the embodiment in which the closed drying circuit 6 with a heat pump is provided ( Figure 8 ), after leaving the laundry compartment 3, the moisture-laden dry air 15 passes through a first (cold) heat exchanger 52 formed by the heat pump's evaporator 52', where the air 15 is cooled to remove moisture from it by condensation. In this case, the condensate can be collected in a removable condensation container or discharged, for example, via a drain pump. The dehumidified and cooled dry air 15 is then directed to a second (hot) heat exchanger formed by the heat pump's condenser 53, where it is heated. The dehumidified and heated air is drawn in by a fan 46 and directed back into the laundry compartment 3 to continue extracting moisture from the laundry.

[0102] The heat pump also includes a compressor 54, which draws coolant fluid through the evaporator 52', where the fluid evaporates at low pressure (absorbing heat from the dry air 15), compresses the coolant fluid, and pushes it into the condenser 53, where the compressed and heated coolant fluid condenses and cools at high pressure (releasing its heat to the dry air 15). After the condenser 53, the coolant fluid passes through an expansion valve 55, which reduces the pressure of the fluid as the temperature drops, and then returns to the evaporator 52', restarting the cycle. Also in the embodiment with a heat pump, a lint filter 51 is arranged upstream of the first heat exchanger 52 (evaporator 52').

[0103] The drum dryer 1 comprises an electronic control system 56 which is connected to the power supply signals of the various functional groups of the drum dryer 1 and controls them ( Figure 8 and 9 ).

[0104] Reference numerals

[0105] Tumble dryer 1

[0106] Shell 2

[0107] Clothing compartment 3

[0108] Drum structure 4

[0109] Motor 5

[0110] Drying circuit 6

[0111] Side wall 7

[0112] Rotation axis 8

[0113] Annular rear edge 9

[0114] Rear opening 10

[0115] Annular front edge 11

[0116] Front opening 12

[0117] Back wall 13

[0118] Ring-shaped receiving seat 14

[0119] Drying airflow 15

[0120] Rear support roller 16

[0121] Rear support portion 17

[0122] Front support roller 18

[0123] Front support portion 19

[0124] Rear support rail 20

[0125] Front support rail 21

[0126] Perforation 22

[0127] Bottom part 23

[0128] First horizontal diameter 24

[0129] Second vertical diameter 25

[0130] First upper left quadrant 26_1

[0131] Second upper right quadrant 26_2

[0132] Third lower left quadrant 26_3

[0133] Fourth lower right quadrant 26_4

[0134] Annular groove 27

[0135] Front gasket 28

[0136] Wall 29

[0137] Rear support plane 30

[0138] Back cover 31

[0139] Rear air channel 32

[0140] Half Shell 33

[0141] Tubular portion 34

[0142] Drag paddle component 35

[0143] Center radial plane 36

[0144] Pulley seat 37

[0145] Parallel ribs 38

[0146] Belt 39

[0147] Stationary front wall 40

[0148] Front receiving seat 41

[0149] Annular groove 42

[0150] Wall 43

[0151] Front support plane 44

[0152] Qianmen 45

[0153] Fan 46

[0154] Motor 47

[0155] Resistor 48

[0156] Heat exchanger 49

[0157] Fresh air flow 50

[0158] Lint filter 51

[0159] First heat exchanger 52

[0160] Evaporator 52'

[0161] Second heat exchanger, condenser 53

[0162] Compressor 54

[0163] Expansion valve 55

[0164] Control system 56

Claims

1. A drum structure (4) of the type used in a drum dryer (1), the drum dryer (1) comprising a laundry compartment (3) for accommodating laundry to be dried and a drying circuit for conveying a drying air flow (15) through the laundry compartment (3), wherein: The drum structure (4) comprises: - a pivoting side wall (7) made of plastic material, of tubular shape, extending circumferentially around the axis of rotation (8) and having an annular rear edge (9) defining a rear opening (10), and an annular front edge (11) defining a front opening (12), - a stationary rear wall (13) which is transverse or orthogonal to the axis of rotation (8) and forms: an annular receptacle (14) which pivotally engages the rear edge (9) of the side wall (7) about the rotation axis (8) and causes the stationary rear wall (13) to close the rear opening (10) of the pivoting side wall (7), and - perforations (22) for allowing the drying air flow (15) to pass through the stationary rear wall (13) in the laundry compartment 3 delimited by the pivoting side wall (7) and the stationary rear wall (13), - a plurality of rear support rollers (16) pivotally supported by a stationary rear support portion (17), and a plurality of front support rollers (18) pivotally supported by a stationary front support portion (19), The side wall (7) forms a rear support rail (20) placed on the rear support roller (16) and a front support rail (21) placed on the front support roller (18) so as to pivotally support the side wall (7) around the rotation axis (8) relative to the stationary rear wall (13) and relative to the rear support part (17) and the front support part (19).

2. The drum structure (4) according to claim 1, wherein: The rear wall ((13)) is made of plastic material.

3. The drum structure (4) according to claim 1 or 2, wherein: The rear wall (13) comprises a circular bottom portion (23) which is delimited by the annular receptacle (14) and in which the entire perforation (22) is formed, Wherein, viewed from the inside of the laundry compartment (3), the bottom portion (23) is imaginarily divided by a first horizontal diameter (24) and a second vertical diameter (25) which are perpendicular to each other and radial to the rotation axis (8): - first upper left quadrant (26_1), - the second upper right quadrant (26_2), - the third lower left quadrant (26_3), - the fourth lower right quadrant (26_4), wherein the permeability of the perforation (22) expressed as a ratio of the channel opening area to the total quadrant area in at least one or more of the first, second, third and fourth quadrants is different from the permeability of the perforation (22) in at least another of the first, second, third and fourth quadrants.

4. The drum structure (4) according to claim 3, comprising a part of the drying circuit (6) which guides the drying air (15) upward from below the side wall (7) to the rear wall (13), in, The total "upper" opening area of ​​the through holes (22) put together in the first quadrant (26_1) and the second quadrant (26_2) is smaller than the total "lower" opening area of ​​the through holes (22) put together in the third quadrant (26_3) and the fourth quadrant (26_4).

5. The drum structure (4) according to claim 3, comprising a part of the drying circuit (6) which guides the drying air (15) downward from above the side wall (7) to the rear wall (13), in, The total "upper" opening area of ​​the through holes (22) put together in the first quadrant (26_1) and the second quadrant (26_2) is greater than the total "lower" opening area of ​​the through holes (22) put together in the third quadrant (26_3) and the fourth quadrant (26_4).

6. The drum structure (4) according to claim 3, 4 or 5, comprising a part of the drying circuit (6) which, seen from the inside of the laundry compartment (3), guides the drying air (15) from the right side of the side wall (7) towards the left to the rear wall (13), in, The total "left" opening area of ​​the through holes (22) put together in the first quadrant (26_1) and the third quadrant (26_3) is smaller than the total "right" opening area of ​​the through holes (22) put together in the second quadrant (26_2) and the fourth quadrant (26_4).

7. The drum structure (4) according to claim 3, 4 or 5, comprising a part of the drying circuit (6) which, seen from the inside of the laundry compartment (3), guides the drying air (15) from the left side of the side wall (7) towards the right to the rear wall (13), in, The total "left" opening area of ​​the through holes (22) put together in the first quadrant (26_1) and the third quadrant (26_3) is greater than the total "right" opening area of ​​the through holes (22) put together in the second quadrant (26_2) and the fourth quadrant (26_4).

8. Drum structure (4) according to any one of the preceding claims, wherein: The annular receiving seat (14) comprises an annular groove (27) facing the annular rear edge (9) and accommodating a front gasket (28) in sliding contact with the rear annular edge (9).

9. A drum structure (4) according to any one of the preceding claims, wherein: The rear support portion (17) is directly formed by the rear wall (13), and the rear support roller (16) includes two rollers arranged in the same rear support plane (30) orthogonal to the rotation axis (8), and the two rollers are in symmetrical positions relative to a vertical plane radial to the rotation axis (8).

10. The drum structure (4) according to any one of the preceding claims comprises a rear cover (31) made of plastic material, the rear cover (31) being connected to the rear wall (13) on the rear side of the drum structure (4), opposite to the side wall (7), and together with the rear wall (13) defining a rear air channel (32) of the drying circuit (6), the rear air channel (32) being connected to the perforation (22).

11. A drum structure (4) according to any one of the preceding claims, wherein: The side wall (7) forms one or more dragging paddle members (35) protruding toward the interior of the laundry compartment (3) and formed integrally with the side wall (7).

12. The drum structure (4) according to claim 11, wherein: The one or more drag paddle members (35) are formed by local recesses of the side wall (7), which form cavities on the radially outer surface of the side wall (7) and corresponding convex protrusions on the radially inner surface of the side wall (7).

13. The drum structure (4) according to claim 11 or 12, wherein: The one or more drag paddle members (35) extend into an axially extending central region of the side wall (7), between the front support rail (21) and the rear support rail (20), but do not reach the front support rail (21) and the rear support rail (20).

14. The drum structure (4) according to claim 11 or 12, wherein: The one or more dragging paddle members (35) have a shape that tapers radially toward the rotation axis (8), and the outer surface of the side wall (7) in the region of the dragging paddle members (35) has a shape that widens radially outwards.

15. The drum structure (4) according to claim 14, wherein: The side wall (7) forms exactly two dragging paddle-like members (37) at diametrically opposed positions relative to a central radial plane (36) of the side wall (7).

16. Drum structure (4) according to any one of the preceding claims, wherein: The side wall (7) forms a cylindrical pulley seat (37) facing radially outwards and bounded on both sides by two annular parallel ribs (38) for securely receiving a belt (39) for transmitting the rotary motion from the electric motor (5) to the side wall (7), Wherein, the pulley seat (37) and the two annular parallel ribs (38) are made of plastic material and are formed integrally with the side wall (7).

17. A drum structure (4) according to any one of the preceding claims, wherein: The rear support rail (20) and the front support rail (21) have a cylindrical shape, while the side wall (7) has a non-cylindrical shape, or has a shape having one or more truncated cone segments and / or having one or more steps formed between adjacent truncated cone segments and / or cylindrical segments.

18. A drum drying machine (1) comprising a drum structure (4) according to any one of the preceding claims.

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