EP2671997A1

EP2671997A1 - Laundry machine comprising a laundry treatment unit with direct drive arrangement

Info

Publication number: EP2671997A1
Application number: EP12170645.1A
Authority: EP
Inventors: Igor Colin; Paolo Barro
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2012-06-04
Filing date: 2012-06-04
Publication date: 2013-12-11
Also published as: WO2013182495A1

Abstract

The present invention is related to a laundry machine (100) provided with a laundry treatment unit (1) comprising: a tub (2), provided with a back wall (4), containing a rotary drum (300); a hub (27), fixed to the back wall (4), supporting a shaft (200) which is provided for supporting and rotating the rotary drum (300); a drive mechanism (400) provided for driving the rotary drum (300) via the shaft (200), the drive mechanism (400) comprising a stator (9). The hub (27) comprises a sleeve (7) and the stator (9) is mounted on this sleeve (7) and is fixed to the sleeve (7) by a fixing element (14) fastened to the sleeve (7).

Description

The present invention relates to a laundry machine (e.g. a washing machine or a washer/drier machine), provided with a laundry treatment unit comprising a direct drive arrangement.
Known laundry machines such as washing machines or washing machines with drying function (also called washer/driers) usually have a laundry treatment unit which is built in a housing of the laundry machine and connected to operation means for operating the laundry treatment unit. Such a laundry treatment unit comprises a tub, wherein a drum is rotatably arranged within the tub and wherein laundry to be washed is placed within the drum. For rotating the drum, a motor is usually provided in a region below or laterally to the tub, being connected to the drum by means of a belt for driving the drum.
As an alternative to the belt driven drum it is possible to use a so called "direct drive motor" for driving the drum. The stator of the direct drive motor is fixed to the rear wall of the tub of the laundry machine, and the rotor of this motor is directly connected to the shaft rotating the drum, so as to be able to rotate this shaft (and therefore the drum) without using a further mechanical transmission device (e.g. a belt pulley system).
The document US 6,681,602 B2 discloses a washing machine including a washing tub having a plastic injection-molded rear wall with a shaft mounted in the rear wall. A laundry drum is connected to the shaft in a rotationally fixed manner. A drive mechanism is connected to the drum for driving the drum, the drive mechanism has a stator support part. The rear wall is plastic injected molded around the stator support part for rotationally fixing the stator support part to the rear wall of the tub.
Disposed on the rear wall of the washing tub is a drive mechanism. The drive mechanism includes a rotor of a bell-shaped form that, like the laundry drum, is connected to the shaft in a rotationally fixed manner. To produce the connection between the rotor and the shaft, a screw is provided, the screwing of the rotor on the shaft being fixed in rotation by positive fitting through an adapted connection.
However the mounting process of the known direct drive solutions is not considered as satisfyingly easy, because of the plurality of steps that have to be carried out by a worker to assembly the tub and the driving means. In particular, distances, gaps, tolerances and positions for electric and/or magnetic means have to be met precisely. A complicated assembling process is a source of defects in this case.
It is the aim of the present invention to provide a laundry machine provided with a laundry treatment unit, comprising a direct driven drum, having a simple structure which allows an easy and fast assembly of the direct drive motor to the washing tub.
It is a further object of the present invention to enable and to provide a stable and precise fixation of a stator component of the direct drive motor to the washing tub.
Applicant has found that by a laundry machine provided with a laundry treatment unit comprising a tub with a hub fixed to its back wall for supporting a shaft rotating a drum, the hub comprising a sleeve on which the stator of a drive mechanism is mounted and fixed by a fixing element fastened to the sleeve, the laundry treatment unit can be assembled in a very easy and quick way.
Above aim and object are solved in particular by a laundry machine provided with a laundry treatment unit comprising:

a tub, provided with a back wall, containing a rotary drum,
a hub, fixed to the back wall, supporting a shaft which is provided for supporting and rotating the rotary drum,
a drive mechanism provided for driving the rotary drum via the shaft, the drive mechanism comprising a stator.

The hub comprises a sleeve and the stator is mounted on the sleeve and is fixed to the sleeve by a fixing element fastened to the sleeve.
Thus, the stator can be fixed to the hub in an easy and stable way. Further, the stator can be mounted in its intended working position.
According to an advantageous embodiment of the invention, the stator is mounted on the sleeve coaxially to the hub.
The hub, itself, is arranged coaxially to a rotational axis which is the rotational axis of the shaft, and therefore of the drum, and also to the rotor which is fixed to the shaft.
Advantageously, by mounting the stator on the sleeve, the stator can be arranged coaxially to the hub and, consequently, arranged coaxially to the drum and to the rotor.
In a further advantageous embodiment of the invention, the tub and/or the hub form a blocking element, wherein the stator abuts against the blocking element in a mounted position on the sleeve.
The blocking element defines a definite position for the stator. A worker can place the stator on the sleeve and fix it thereto. Thus, the manufacturing process of the laundry treatment unit is simplified.
In a further advantageous embodiment of the invention, the blocking element is a block step.
A block step can be easily provided in the manufacturing process and defines a definite working position of the stator.
In a further advantageous embodiment the tub and the hub form a cylindrical forming comprising a cylindrical base and the sleeve.
A cylindrical forming comprising a cylindrical base and the sleeve where the stator is mounted to, integrates the components for mounting and positioning of the stator.
According to a further advantageous embodiment of the invention the block step is formed between the cylindrical base and the sleeve.
Cylindrical base and sleeve can be both formed such that the sleeve is formed by the hub which is embedded in the plastic material of the tub and that the cylindrical base is formed by the tub enclosing the hub. Thus, the manufacturing process is simplified.
In a further advantageous embodiment of the invention the fixing element is a ferrule.
Thus, the stator can be clamped on the sleeve, in particular between blocking element and ferrule. The mounting process is simplified even more.
According to a further advantageous embodiment of the invention the ferrule has an internal thread provided on an inner side, wherein the ferrule is screwed to the sleeve and fixes the stator on the sleeve by pressing the stator against the block step.
In such a configuration, the stator can be easily fixed to the sleeve. The worker has to carry out only one screwing action and the stator can be mounted in its intended working position without any further adjustment steps.
In a further advantageous embodiment of the invention the hub comprises an inner shell, wherein the inner shell forms the sleeve.
In such a configuration a very rigid and stable support for the stator is created, in particular when the hub is made of metal.
In a further embodiment of the invention the hub comprises an outer shell and a base plate connecting the inner shell with the outer shell.
Thus, an even more rigid support for the stator is created.
In a further embodiment of the invention the hub is at least partially enclosed by an enclosure made of the plastic material of the tub.
In such a configuration, the hub is very rigidly fixed to the tub. Further the material of the hub, which is embedded in the plastic material of the tub, is protected from the contact with water and thereby from corrosion.
In a further embodiment of the invention the outer shell is completely enclosed by the enclosure and the inner shell is partially enclosed by the enclosure, wherein the inner shell projects in direction of a rotational axis beyond the enclosure and wherein the block step is formed by the enclosure.
Thus, the block step is formed by the enclosure, i.e. by the plastic material, wherein the inner shell of the hub projects beyond the block step. This formation of the block step can be produced advantageously in an injection moulding process and improves therefore the manufacturing process.
According to a further embodiment of the invention the stator and the sleeve comprise a centering device for fixing the angular position of the stator with respect to the sleeve.
The centering device provides a rotationally fixed fastening or in other words a torque-proof connection of stator and sleeve. Thus, the stator cannot rotate, when the rotational field is generated.
According to a further embodiment of the invention the centering device comprises at least one rib extending longitudinally from the stator (or in a further embodiment from the sleeve) in direction of the rotational axis, and at least one slot extending longitudinally in the sleeve (or in a further embodiment in the stator) in direction of the rotational axis, wherein the rib engages into the slot.
In such configuration a worker can install the stator to the cylindrical forming in the only one correct position, i.e. where the rib can engage into the slot. Therefore, the position of the stator on the cylindrical forming is precisely defined. Electrical connection means, e.g. a plug or a socket, provided on the stator are arranged mandatorily in a predetermined position.
In a further embodiment of the invention the stator comprises a ring wherein the ring abuts against the blocking element in a mounted position of the stator and wherein the fixing element presses the ring against the blocking element.
Thus, a very rigid fixation for the stator on the cylindrical forming is provided. Further the stator is precisely fixed in its predetermined position.
The invention will be described in further detail with reference to the drawings, in which

FIG 1: schematically illustrates a lateral cross section of a laundry machine according to the invention;
FIG 2: illustrates an exploded perspective view of a laundry treatment unit of a laundry machine according to the invention;
FIG 3: illustrates a detailed sectional and schematic view of a back wall of the laundry treatment unit comprising a direct driven rotary drum according to FIG 2.

FIG 1 schematically illustrates a lateral cross section of a laundry machine 100 according to the invention.
The laundry machine 100 illustrated in Figure 1 is a washing machine of the front loading type; it is however clear that the invention can be applied as well to a top-loading washing machine and to a washer/drier, both of the front loading and top loading type.
Advantageously the laundry machine 100 comprises a housing 110 containing a laundry treatment unit 1 comprising a washing tub 2 (or simply tub), preferably supported by coils and dampers, not illustrated, fixed to the housing 110.
Tub 2 enclosed a rotary drum 300 (or simply drum), wherein laundry can be loaded to be submitted to a washing process (or also to a drying process in the case of a washer/drier). The drum 300 is provided, for its rotation, with a shaft 200, protruding from its back surface, rotatably supported by a hub 27 (provided with bearings, not illustrated) fixed to the back wall 4 of the tub 2; preferably the hub 27 is fixed to the 2 by an at least partial over-injection of the tub 2 on the hub 27.
Advantageously the hub 27 is provided with a sleeve 7, which is substantially perpendicular to the back wall 4 of the tub and which is substantially coaxial, in the assembled condition, to the shaft 200.
Laundry machine 100 preferably comprises a water inlet circuit 120, adapted to take in the tub 2 a washing liquid (e.g. water and water mixed with washing/rinsing products), and a water draining circuit 130, adapted to drain the washing liquid from the tub 2.
Laundry machine 1 may comprise also further electronic and mechanical devices (control units, level sensors, etc), which will not be described in detail.
FIG 2 illustrates an exploded perspective view of a laundry treatment unit 1 comprising a direct driven rotary drum 300. The laundry treatment unit 1 comprises a tub 2 which preferably a back wall 4, preferably with enforcement ribs 23. The ribs 23 are advantageously arranged concentrically around a cylindrical forming 3 which is arranged in a central position of the back wall 4 and provide structural rigidity which is necessary due to vibrations being generated by the rotating drum. Further the ribs extend longitudinally in a radial direction. The tub 2 is preferably made of a plastic material in an injection moulding process.
Laundry treatment unit 1 is provided with a drive mechanism 400 comprising an electric motor having a ring-shaped stator 8 provided with a plurality of poles 12. The poles 12 are distributed circumferentially around a center of the stator 8. Preferably, windings 24 are wound around the poles 12 for enabling a rotating magnetic field to be generated. The stator 9 comprises a ring 11, e.g. a ring plate or a ring element, which serves as a basis of the stator and to which the poles 12 and the windings 24 are fastened. The ring 11 has a center hole with an inner wall 26. The inner wall advantageously has a centering device 13 which can be formed as ribs or webs. Said centering device 13 advantageously extends longitudinally in direction of a rotational axis A.
Advantageously the tub 2 and the hub 27 form a cylindrical forming (or cylindrical body) 3 comprising a cylindrical base 6 and the sleeve 7.
Preferably, but not necessarily, at least part of the sleeve 7 may be by the plastic material of the tub 2, since the tub 2 is advantageously over-injected (or over-moulded) on the hub 27, so as to at least partially enclosing the latter.
The sleeve 7 advantageously has slots 8a, 8b formed thereto, e.g. arranged on opposite sides of the wall of the sleeve 7. The slots 8a, 8b extend longitudinally in direction of the rotational axis A. The slots 8a, 8b are formed in such a way that the centering device 13 of the stator 9 fit thereto. The diameter of the center hole of the ring 11 is dimensioned such that the ring 11, and thereby the stator 9 can be plugged (or mounted or fitted) on the sleeve 7. In this case the centering device 13 engages the slots 8a, 8b and provides a fixation in a rotationally fixed manner.
The stator 9 can be moved on the sleeve 7 until the centering device 13 contacts an end of the slots 8a, 8b and/or until the ring 11 abuts against the block step 5. Thus, it is secured that the stator 9 is arranged in a prefixed final position with respect to slot 7.
Further a ferrule 14 is advantageously provided having an inner side 16 and an outer side 17. On the outer side 17 of the ferrule 14 recesses 15 can be provided. The inner side 16 of the ferrule 14 can be provided with a thread. In general, the ferrule 14 is a ring-shaped element being dimensioned such that it can be screwed by means of the thread on its inner side 16 onto a mating thread provided on the outer side of the sleeve 7. The ferrule 14 is advantageously screwed until it abuts to the ring 11 of the stator 9 and, thus, fixes the stator relative to the longitudinal extension of the rotational axis A.
A rotor 10 having an end wall 20 and a circumferential wall 21 is further provided. The drum 300 is arranged inside the tub 2. The shaft 200, being torque-proof connected to the drum 300 (i.e. shaft 200 and drum 300 are fixed one another, and therefore in particular they are fixed with respect of reciprocal rotation), is advantageously rotationally supported by bearings, not illustrated, provided inside the hub 27. Further the shaft 200 is advantageously fixed to a fastening section 25 of the rotor 10. Thus, a rotation of the rotor 10 effects a rotation of the shaft 200 and of the drum 300 fixed to the shaft 200.
On the inner side of the circumferential wall 21 of the rotor 10, magnets 500 (see FIG. 1) are advantageously arranged circumferentially along the circumferential wall 21 and fixedly attached to the circumferential wall 21 for drawing or pushing the rotor 10 into rotation. For this purpose the rotor 10 is advantageously arranged in a final position such that the magnets are arranged adjacent to the poles 12 of the stator 9 and that the radial distance between the magnets and poles 12 is minimal, when the rotor 10 rotates. Usually windings are wound around the poles 12 for providing a rotating magnetic field for driving the rotor 10.
FIG 3 illustrates a detailed sectional and schematic view of a back wall 4 of the laundry treatment unit 1 comprising a direct driven rotary drum. The hub 27 comprises an inner shell 28 and an outer shell 28, both integrally formed with a base plate 30. The hub 27 is made of a rigid and stable material such as metal, e.g. a steel material or aluminium.
The hub 27 is advantageously at least partially enclosed by an enclosure 19, wherein the enclosure 19 is formed by the plastic material of the tub 2 (i.e. enclosure 19 is a layer made of the plastic material of the tub 2). The outer shell 29 and the base plate 30 are advantageously completely enclosed by plastic material. Thus, the hub 27 is rigidly fixed to the tub 2. The inner shell 28 is supported on an outer side by the enclosure 19, wherein the enclosure 19 forms the cylindrical base 6 on the outer side of the inner shell 28. The inner shell 28 preferably protrudes partially outside the enclosure 19, wherein a mating thread 18 is preferably provided on the protruding part of the inner shell 28. Bearing seats 30a, 30b can be provided on the interior side of the inner shell 28. Bearings for supporting the shaft 300can be positioned there.
The stator 9 is not shown in this view and shall be provided plugged on the outer side of the sleeve 7 until the final position of the stator 9 is reached. E.g. the stator 9 and in particular the ring 11 can abut against the block step 5. The ferrule 14 may be screwed onto the mating thread 18 by means of its thread arranged on its inner side 17. Thus, the stator 9 can be fixedly arranged on the sleeve in its prefixed final position.
In the case of repair or maintenance, the rotor 10 can be detached from the shaft 200 and removed. Then, the ferrule 14 can be detached from the mating thread of the sleeve 7 and the stator 9 can be detached from the sleeve 7. Therefore it is very easy to change the stator 8 and/or the rotor 10 in the case of damage.

Claims

Laundry machine (100) provided with a laundry treatment unit (1) comprising:
- a tub (2), provided with a back wall (4), containing a rotary drum (300),

- a hub (27), fixed to said back wall (4), supporting a shaft (200) which is provided for supporting and rotating said rotary drum (300),

- a drive mechanism (400) provided for driving said rotary drum (300) via said shaft (200), said drive mechanism (400) comprising a stator (9),
characterized in that
said hub (27) comprises a sleeve (7) and said stator (9) is mounted on said sleeve (7) and is fixed to said sleeve (7) by a fixing element (14) fastened to said sleeve (7).
Laundry machine (100) according to claim 1, characterized in that said stator (9) is mounted on said sleeve (7) coaxially to said hub (27).
Laundry machine (100) according to one of the preceding claims, characterized in that said tub (2) and/or said hub (27) form a blocking element (5), wherein said stator (9) abuts against said blocking element (5) in a mounted position on said sleeve (7).
Laundry machine (100) according to claim 1, characterized in that said blocking element (5) comprises a block step (5).
Laundry machine (100) according to one of the preceding claims, characterized in that said tub (2) and said hub (27) form a cylindrical forming (3) comprising a cylindrical base (6) and said sleeve (7).
Laundry machine (100) according to claim 5 referred back to claim 4, characterized in that said block step (5) is formed between said cylindrical base (6) and said sleeve (9).
Laundry machine (100) according to one of the preceding claims, characterized in that said fixing element is a ferrule (14).
Laundry machine (100) according to claim 7, characterized in that said ferrule (14) has an internal thread provided on an inner side (17), wherein said ferrule (14) is screwed to said sleeve (7) and fixes said stator (9) on said sleeve (7) by pressing said stator (9) against said block step (5).
Laundry machine (100) according to one of the preceding claims, characterized in that said hub (27) comprises an inner shell (28), wherein said inner shell (28) forms said sleeve (7).
Laundry machine (100) according claim 9, characterized in that said hub (27) comprises an outer shell (29) and a base plate (30) connecting said inner shell (29) with said outer shell (29).
Laundry machine (100) according to one of the preceding claims, characterized in that said hub (27) is at least partially enclosed by an enclosure (19) made of plastic material of said tub (2).
Laundry machine (100) according to claim 11 referred back to claim 10, characterized in that said outer shell (29) is completely enclosed by said enclosure (19) and that said inner shell (28) is partially enclosed by said enclosure (1), wherein said inner shell (28) projects in direction of a rotational axis (A) of said drum (300) beyond said enclosure (19) and wherein said block step (5) is formed by said enclosure (19).
Laundry machine (100) according to one of the preceding claims, characterized by comprising a centering device (13, 8a, 8b) for fixing the angular position of said stator (9) with respect to said sleeve (7).
Laundry machine (100) according to claim 13, characterized in that said centering device (13) comprises at least one rib extending longitudinally in direction of said rotational axis (A) and at least one slot (8a, 8b) extending longitudinally in direction of said rotational axis (A), wherein said rib engages into said slot (8a, 8b).
Laundry machine (100) according to one of the claims 3 to 14, characterized in that said stator (9) comprises a ring (11) wherein said ring (11) abuts against said blocking element (5) in a mounted position of the stator (9) and wherein said fixing element (14) presses said ring (11) against said blocking element (5).