The invention lies in the field of washing appliances. The invention relates to a drive apparatus for a washing machine having a laundry drum that is mounted in a floating manner through at least one approximately horizontal shaft and through bearings either in the rear wall or within a stiff supporting part that is fitted to the rear wall of a lye or suds container and is driven directly by a flat electric motor mounted on the rear face of the suds container on the supporting part. The stator and the rotor of the electric motor are connected to one another through a bearing and are jointly removable from the washing machine.
German Published, Non-Prosecuted Patent Application DE 195 47 745 A1, corresponding to U.S. Pat. No. 5,862,686 to Skrippek and to U.S. Pat. No. 5,894,746 to Skrippek, discloses such a drive apparatus for a front-loading washing machine. The drive apparatus has an electric motor that can be removed from the shaft as an entity. Therein, the stator in conjunction with a mounting disk also carries out the function of the supporting part. A bearing sleeve is formed as a flange on the stator, and forms bearing seats for roller bearings for the laundry drum shaft, which is surrounded by a hollow shaft. The hollow shaft is, itself, attached to the free end of the shaft by a screw connection. The hollow shaft is a component of the rotor, which is essentially in the form of a bell-shaped flange and has magnetic poles on the internal circumferential face of the bell-shaped attachment. The stator and the rotor can be removed jointly from the rear face of the suds container by undoing the attachment screws that connect the stator to the mounting disk, and undoing the central screw connection between the hollow shaft and the shaft, with the bearing between the stator and the rotor, which at the same time forms the bearing for the shaft, remaining between the stator and the rotor. Accordingly, once the stator and the rotor have been removed, the shaft remains, together with the laundry drum, without any support in the washing machine, and must be readjusted with respect to the stator when the electric motor is refitted. Such readjustment makes the assembly process more difficult.
It is accordingly an object of the invention to provide a drive apparatus for a washing machine that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that simplifies refitting and improves the drive device such that the electric motor can be removed more easily and more quickly from the rear wall of the suds container.
With the foregoing and other objects in view, in a washing machine having a suds container with a rear wall and a laundry drum mounted within the suds container there is provided, in accordance with the invention, a drive apparatus including a flat electric motor for directly driving the laundry drum, the motor mounted on the rear wall of the suds container, the motor having a stiff support connected to the rear wall of the suds container, a first bearing, a rotor having a hollow shaft, and a stator connected to the support, the stator and the rotor connected to one another through the first bearing and being jointly removable from the washing machine; a second bearing, a substantially horizontal shaft for mounting the laundry drum within the suds container in a floating manner, the shaft mounted within the support through the second bearing, the shaft having a shaft journal projecting out of the support, the shaft journal being surrounded by the hollow shaft of the rotor, and the stator and the rotor being jointly connected to the shaft journal.
With the objects of the invention in view, in a washing machine having a suds container with a rear wall and a laundry drum mounted within the suds container there is also provided a drive apparatus including a flat electric motor for directly driving the laundry drum, the motor mounted on the rear wall of the suds container, the motor having a first bearing, a rotor having a hollow shaft, and a stator connected to the rear wall, the stator and the rotor connected to one another through the first bearing and being jointly removable from the washing machine, a second bearing, a substantially horizontal shaft for mounting the laundry drum within the suds container in a floating manner, the shaft mounted within the rear wall through the second bearing, the shaft having a shaft journal projecting out of the rear wall, the shaft journal being surrounded by the hollow shaft of the rotor, and the stator and the rotor being jointly connected to the shaft journal.
The objectives of the invention are achieved by mounting the shaft through bearings either in the rear wall or within a stiff supporting part that is fitted to the rear wall, and by having a shaft journal that projects out of the rear wall of the suds container or out of the supporting part, that is surrounded by a hollow shaft formed by the rotor of the motor, and onto which the stator and the rotor of the electric motor can be pushed jointly.
On one hand, the invention ensures that the shaft is mounted securely in the rear wall or in the supporting part and, on the other hand, it ensures that the motor can be removed from the shaft as an entity. Even when the motor has been pulled off, the bearing for the shaft remains in the washing machine, so that the laundry drum can still be rotated even after removal of the motor.
Because the motor is supplied ready assembled as an entity to the manufacturer""s works for washing machines, it can have the suds container system added to it easily there through the supporting part. Because extremely stringent requirements are placed on maintaining a small air gap (which is also as far as possible of the same size in all machines) between the stator and the rotor poles of an electric motor and on the central bearing, and because these requirements do not need to be complied with during assembly in a washing machine factory, a motor is provided as a complete entity according to the invention. The complete motor can easily be pushed onto the end of a shaft journal of the shaft of the laundry drum. The motor stator is connected to the supporting part, for example, by screw connections.
To allow the stator to be screwed to the supporting part, the rotor has apertures in its bottom part. The apertures ensure cooling of the stator windings so that the motor cannot become overheated, while, at the same time, having dimensions complying with requirements.
Thus, the motor has an open form, whose heat-producing components are cooled by the environmental air on all sides. Even the low motor rotation speed during the washing mode is still sufficient for the rotor to produce a heat-dissipating air movement.
As such, the motor can be completely assembled at the factory of a motor supplier, and can then be supplied to the washing machine factories, without any manufacturing tolerances in the washing machine factory having a negative influence on the electric motor. In accordance with another feature of the invention, the stator is connected to the cast supporting part or supporting star by a large number of screws, and the cast supporting part is normally disposed on the rear wall of the suds container, in which case further connections can also be provided between the rear wall or the casing wall of the suds container and the stator, as well, to provide additional protection for the stator.
In accordance with a further feature of the invention, one of the two bearings of the shaft at the same time forms the bearing between the stator and the rotor. The bearing is disposed between the shaft journal, which is adjacent to the shaft, and the hollow shaft surrounding the rotor. As such, the bearing that connects the stator to the rotor has precisely the same dimensions as the bearing through which the shaft is mounted in the bearing sleeve formed by the supporting part.
In accordance with an added feature of the invention, the support or the rear wall has a bearing sleeve and the second bearing is adjacent the bearing sleeve.
In accordance with an additional feature of the invention, the support or the rear wall has a bearing sleeve with an outer circumference, the stator has a central bearing sleeve with an inner circumference, and the outer circumference of the bearing sleeve is inserted into the inner circumference of the central bearing sleeve.
The bearing that supports the rotor in the stator advantageously rests axially against the end face (pointing away from the suds container) of the bearing sleeve of the supporting part. The bearing sleeve of the stator, which holds the bearing that is disposed between the stator and the rotor, additionally is disposed such that it can be pushed or plugged onto the outer circumference of the bearing sleeve of the supporting part. As such, the robustness of the motor is even further increased. The mounting of the bearing sleeve of the stator on the bearing sleeve of the supporting part with a push fit can also be used as the only attachment of the stator. As such, the need for the screw connections between the stator and the supporting part is eliminated.
In accordance with yet another feature of the invention, the rotor has a circumferential portion and openings disposed in a region between the hollow shaft and the circumferential portion, and the stator is connected to the support or rear wall through the openings.
In accordance with yet a further feature of the invention, the stator has pole packs and the rotor has a circumferential portion with an inner surface, a bell-like flange disposed at the circumferential portion pointing towards the suds container, and magnetic poles disposed at the inner surface opposite the pole packs and spaced apart from the pole packs to define an air gap therebetween.
In accordance with yet an added feature of the invention, the rotor has air movement parts for assisting air movement when the rotor rotates.
In accordance with yet an additional feature of the invention, the motor is advantageously in the form of an electronically commutated DC motor that, due to the lack of brushes, allows a long life.
In accordance with again another feature of the invention, the rotor is at least partially formed by an annular pack of electrical steel sheets, with permanent magnet segments disposed thereon. The permanent magnet segments produce a powerful torque, and the electrical steel sheets form a particularly good magnetic return path. The required laminated packs can be produced in a relatively uncomplicated manner, and cost-effectively, by automation of the stacking process. The pole packs of the stator are advantageously electrical steel sheets and are fitted with coils having the field windings.
In accordance with again a further feature of the invention, the stator has pole packs and the pole packs are electrical steel sheets fitted with coils having field windings.
In accordance with again an added feature of the invention, the motor is a switched reluctance motor. As such, the rotor is a ferromagnetically relatively poorly permeable material. The construction of the stator is comparable to that of the electronically commutated DC motor. The configuration results in the particular advantage of a more cost-effective configuration of the rotor, which does not require any expensive magnetic materials.
To simplify the assembly process such that it is reproducibly accurate, in accordance with again an additional feature of the invention, the centered connection of the rotor in a rotationally fixed manner on the shaft can be supplemented by an interlocking profiled shaft, a profiled hub, an adjusting spring, or a conical or tongue and groove connection.
In accordance with still another feature of the invention, the rotor is connected to the shaft journal in a centered connection and the centered connection is rotationally fixed in an interlocking manner by one of the group consisting of a profiled shaft, a profiled hub, an adjusting spring, a conical connection, and a tongue and groove connection.
In accordance with still a further feature of the invention, the stator and the rotor are jointly pushed onto the shaft journal.
In accordance with a concomitant feature of the invention, the first bearing is disposed between the stator and the rotor. Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a drive apparatus for a washing machine, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.