The present invention relates in general to electric household appliances, and in particular, but not exclusively, to washing machines.

More specifically, the invention concerns an electric household appliance including

a support structure which is stationary in operation,

a movable member, which is in particular rotatable, in said support structure, a reversible electrical machine adapted to operate as a motor for moving said movable member and as a generator when it is driven in rotation by said movable member in the absence of an electric power supply; and

at least one auxiliary electrical device;

the arrangement being configured such that in case of malfunction or of an absence of electric power supply while said movable member is moving, said at least one auxiliary electrical device is supplied by said electrical machine until the kinetic energy of said movable member becomes lower than a predetermined threshold.

An electric household appliance of this type is described in the prior Italian patent application no. RM2014A000403, filed on 21 July 2014. This prior application, which may be invoked against the present application solely for the assessment of the requirement of novelty, describes an electric household appliance equipped with a door, wherein the aforementioned auxiliary electrical device is a door-lock device associated with this door.

One object of the present invention is to provide an electric household appliance of the type defined initially, wherein the use of a reversible electrical machine adapted to act as a motor and as a generator enables further functions of the appliance to be maintained in case of interruption of the electric power supply, and until the aforesaid movable member is again moving with a kinetic energy above a predetermined threshold. This object is achieved according to the invention by means of an electric household appliance whose salient characteristics are defined in the attached Claim 1. The aforesaid at least one auxiliary electrical device may be, for example, an active vibration-damper device including an electric magnetorheological fluid actuator and/or a display device of a user interface. Further characteristics and advantages of the invention will be apparent from the following detailed description which is given purely by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 is a schematic representation of a washing machine according to the present invention;

Figure 2 is a functional diagram of a control system included in an electric household appliance according to the present invention; and

Figure 3 is a detailed electrical diagram of a control unit included in an electric household appliance according to the present invention. In Figure 1 , the number 1 indicates the an electric household appliance according to the present invention, which is, in particular, a washing machine (a washing machine for laundry).

In the embodiment illustrated by way of example, the machine 1 comprises a support structure S which is stationary in operation, in which a member C, in particular a laundry holding basket or drum, is mounted rotatably in a washing chamber or bath WC.

The assembly formed by the movable member C arid the washing chamber WC is suspended in the support structure S by a plurality of elastic members (springs) 30.

The machine 1 is also equipped with an electronic control unit 2 and a reversible electrical machine 3.

The electrical machine 3 is, in particular, of the rotary type and is adapted to operate as a motor for driving the member C in rotation and as a generator when it is driven in rotation by this member C in the absence of an electric power supply. The reversible electrical machine 3 is, for example, a machine of the brushless type, and is controlled in operation by the unit 2, in the manner described below.

In the embodiment illustrated by way of example in Figure 1 , the machine 1 comprises (at least) an auxiliary electrical device 4 which is, in particular, an active vibration-damper device including an electric magnetorheological fluid actuator 40.

In a known way, the actuator 40 comprises a stator 40S and a rotor 40R, to which are fastened the respective arms 41 and 42 connected, respectively, to the washing chamber WC and to the support structure S of the machine 1.

In a known way, a magnetorheological fluid is interposed between the rotor 40R and the stator 40S, in which fluid a magnetic field of variable intensity may be generated by means of a solenoid or the like to cause a corresponding variation in the viscosity of this fluid.

The current supplied to the solenoid during operation is controlled by the electronic unit 2 on the basis of signals supplied by one or more transducers, also of a known type, adapted to supply electrical signals indicative of the level of the vibrations of the washing chamber WC and the associated basket C.

Although a single active vibration-damper device is present in the illustrated exemplary embodiment, a plurality of these devices, in particular three, could be associated with the washing chamber WC, to detect the intensity of oscillation of the washing chamber WC along three coordinate axes.

Additionally, although the active vibration-damper device 4 described above is of the rotary type, it could be replaced by a linear active damper device, in which the rotor and stator are replaced by two members capable of relative linear movement, one of these members being connected to the washing chamber WC and the other to the support structure S of the machine 1 , a magnetorheological fluid, whose density is electrically controllable, being interposed between these members. In the embodiment according to Figure 1 , the machine 1 further comprises a numeric and/or alphabetic display device 5 forming part of the man-machine interface with which the machine 1 is equipped. This display device 5 is also controlled by the electronic control unit 2.

With reference to Figure 2, the control unit 2 illustrated therein operates in programmed modes defined in a logic unit U, which may also be incorporated in the control unit 2.

The coupling between the control unit 2 and the electrical machine 3 enables the latter to be actuated as a motor, and also enables power to be supplied to the control unit 2 itself, as described more fully below.

With reference to Figure 3, a description will now be given of a possible more detailed arrangement of the control unit 2 and the corresponding connections to the electrical machine 3 and to the active vibration-damper device 4.

The control unit 2 comprises a programmable microcontroller 21 , connected for operation to a power unit 22 for controlling and supplying power to the electrical machine 3, and a first electronic switch 23', in the form of an active device such as a MOSFET or IGBT transistor, controlled by the microcontroller 21 by means of a PWM (Pulse Width Modulation) signal, to modulate the direct current supply voltage present on a bus at the necessary value to energize the solenoid of the actuator 40 of the damper device 4.

By means of the switch 23', the microcontroller 2 may modulate the intensity of the current supplied to the solenoid of the magnetorheological fluid actuator 40, and consequently the viscosity of this fluid, and therefore the reaction of the damper device 4 to the vibrations/oscillations of the washing chamber assembly WC.

The control unit 2 may further comprise a second electronic switch 23", in the form of an active device, for example a MOSFET or IGBT transistor, controlled by the microcontroller 21 , to provide fast disconnection of the solenoid of the actuator 40 for safety purposes, in case of a short circuit. Said first 23' and second 23" switch are connected in series with one another.

The control unit 2 may further comprise an electronic protection circuit 25', connected between the conductors of the direct current bus between which the supply voltage of the unit 2 is present in operation.

The protection circuit 25' is adapted to measure the value of the voltage between the conductors of said bus, and to intervene if there is a loss of mains power, to provide a braking action on the electrical machine 3 if necessary.

The electronic control unit 2 may further comprise a current sensor device 25", in series with the switches 23' and 23", and (in a way which is not illustrated) with the solenoid of the magnetorheological fluid actuator device 40, to detect the strength of the current flowing in these devices. The current detected in this way may serve as a feedback signal, and if necessary to detect malfunction or fault conditions such as a short circuit or an open circuit of the solenoid.

In case of a malfunction or fault or an interruption in the electric power supply while the movable member (basket) C is moving, the electrical machine 3 ceases to operate as a motor and, being driven in rotation by the rotatable member C, operates as an electrical generator and keeps a voltage available on the bus of the control unit 2, enabling the control of the vibration-damper device 4 to continue at least until the kinetic energy of the rotatable member C is above a predetermined value. The damper device 4 therefore continues to provide a damping action on the vibrations and therefore a stabilizing action on the washing chamber assembly WC, in practice until the basket C has become stationary.

As an alternative or in addition to the control of the vibration-damper device 4, the control unit 2 may be designed so that, in case of a malfunction or interruption in the electric power supply, the operation of other auxiliary devices installed in the machine 1 is ensured until the rotatable member C has practically become stationary. For example, the control unit 2 may be designed to maintain the functionality of the display device 5, so that any messages can continue to be supplied to the operator, or the functionality of a magnetorheological fluid multi-function knob, or the water discharge pump or sensor devices of the machine 1.

Naturally, the principle of the invention remaining the same, the forms of embodiment and the details of construction may be varied widely with respect to those described and illustrated, which have been given purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the attached claims.