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(11) | EP 2 079 090 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Power supply connection device for household and industrial appliances |
| (57) A power supply connection device includes a supply unit (3), a main switch (12),
for selectively connecting the supply unit (3) to electric mains (11) in a closed
state, and a thermoactuator (17), operable to controllably open the main switch (12)
and disconnect the supply unit (3) from electric mains (11).
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[0001] The present invention relates to a power supply connection device for household and industrial appliances.
[0002] It is known that the requirement to minimize power consumption has a leading role in development of virtually any kind of electric appliances, in particular household appliances, such as clothes washers, dishwashers, steam irons and the like.
[0003] Especially by the end of use cycles, appliances may remain in an active or in a standby state, whereby an amount of power is anyway drawn from mains, although the appliances are not actually exploited.
[0004] For example, a user may program a washing cycle of a washer and let the appliance perform the cycle unattended. So, when the cycle is terminated, quite a long time may pass before the user manually disconnects the washer from mains supply.
[0005] A steam iron may be left in on-state for a period, while it is not used. A user may need to stop ironing and attend to another activity that is expected to take only few minutes, but turns out to last longer. The user may prefer, in this circumstances, to maintain iron and steam temperature. However, if the pause is too long, pointless power consumption takes place.
[0006] Solutions proposed so far are not satisfactory. Control circuitry has been improved to automatically bring appliances into standby state under certain conditions and to reduce standby power consumption. For example, switch to standby state may take place as soon as a use cycle has been completed or after a period in which an appliance has remained inoperative.
[0007] However, even in the standby state power consumption is not completely eliminated. Since appliances may often remain in standby for several hours, overall consumption may in fact be quite high.
[0008] The object of the present invention is to provide a power supply connection device, that overcome the above described limitations.
[0009] According to the present invention, a power supply connection device is provided, as claimed in claim 1.
[0010] For the understanding of the present invention, some embodiments thereof will be now described, purely as non-limitative examples, with reference to the enclosed drawings, wherein:
- figure 1 is a simplified block diagram of an electrical appliance;
- figure 2 is a more detailed block diagram of a power supply connection device incorporated in the appliance of figure 1 and made in accordance with one embodiment of the present invention, in one operating condition;
- figure 3 is a block diagram of the power supply connection device of figure 2, in another operating condition;
- figure 4 is a flowchart relating to operation of a power supply connection device according to the invention, in one embodiment;
- figure 5 is a flowchart relating to operation of a power supply connection device according to the invention, in another embodiment;
- figure 6 is a block diagram of a power supply connection device according to another embodiment of the present invention, in one operating condition; and
- figure 7 is a block diagram of the power supply connection device of figure 6, in another operating condition.
[0011] In figure 1, a household appliance, that in the embodiment herein described is a washer, is generally designated by the reference numeral 1. However, it is understood that the example is not to be considered in any way as limiting and the invention also applies to any kind of household and industrial appliance, such as dishwashers, cleaners, steam irons and the like.
[0012] The appliance 1 comprises a body 2, a supply unit 3, a mechanical driving assembly 5, a fluid circulation assembly 6, a selective connection device 8 and a control unit 10.
[0013] The body 2, which is not shown in detail, may be of any known type and may comprise a washing compartment, with movable parts driven by the mechanical driving assembly 5 or by the fluid circulation assembly 6; a door, possibly provided with a safety lock device to prevent operation of the appliance when the door is not properly locked; a detergent dispenser and actuating means for controllably opening the dispenser and releasing the detergent at a given stage of a washing cycle.
[0014] The supply unit 3 is selectively connectable to electric mains 11 (hereinafter simply mains) through the selective connection device 8, as explained later on.
[0015] When coupled to the mains 11, the supply unit 3 feeds the mechanical driving assembly 5, the fluid circulation assembly 6 and the control unit 10.
[0016] The mechanical driving assembly 5 and the fluid circulation assembly 6 are operated by the control unit 10 through control signals SC. A plurality of sensors (not shown) may provide the control unit 10 with measure signals SM indicative of quantities required for the purpose of control.
[0017] The selective connection device 8 comprises a main switch 12, arranged along a supply line 13 between the supply unit 3 and the mains 11, and an actuator 15, also controlled by the control unit 10.
[0018] The main switch 12 is manually operable by a user. Moreover, the actuator 15 is coupled to that the main switch 12, so that the main switch 12 is brought into an open state when the actuator 15 is energized by the control unit 10.
[0019] As illustrated in figures 2 and 3, the actuator 15 comprises a thermoactuator or wax motor 17, and a coupling mechanism 18 for coupling the wax motor 17 to the main switch 12. The wax motor 17 includes a cylinder 20, filled with a thermosensitive wax, a PTC thermistor 21, thermally coupled to the cylinder 20, and a shaft 22. The shaft 22 is arranged in the cylinder 20, projecting from an end thereof, and is axially slidable between a retracted position (figure 2) and an extracted position (figure 3) in response to changes in volume of wax inside the cylinder 20. In the embodiment herein described, the wax motor 17 is of the push-type. Namely, when a current I is supplied to the PTC thermistor 21, heated wax expands and the shaft 22 is brought to the extracted position. When current supply is removed, wax cools down and shrinks, and the shaft 22 is moved back to the retracted position, e.g. by a return spring, here not shown. In another embodiment, not shown, the wax motor 17 may be of the pull-type, i.e. the shaft 22 is arranged to normally stay in the extracted position and to move to the retracted position when the PTC thermistor 21 is energized.
[0020] The coupling mechanism 18 has an input member 24 connected to the shaft 22 and an output member 25 releasably connectable to a moving contact 26 of the main switch 12. The coupling mechanism 18 may comprise any known system, such as a lever system, configured so that movements of the input member 24 are amplified by the output member 25. More precisely, the coupling mechanism 18 amplifies the stroke of the shaft 22 from the retracted position to the extracted position as required to displace the moving contact 26 from a closing position (figure 2), in which the main switch 12 is closed and the supply unit 3 is connected to the mains 11, to a opening position (figure 3), in which the main switch 12 is open and the supply unit 3 is disconnected from the mains 11.
[0021] Connection between the output member 25 of the coupling mechanism 18 (hence, of the wax motor 17) and the moving contact 26 of the main switch 12 is unidirectional. In practice, when the wax motor 17 is energized and the shaft 22 is moved to the extracted position, the output member 26 comes in contact with the moving contact 26 and causes the main switch 12 to open. However, when the wax motor ceases to be energized and the shaft 22 moves back to the retracted position, connection between the output member 26 and the moving contact 26 is released. Accordingly, the main switch 12 may remain in the open state until a user manually closes it.
[0022] As above mentioned, the actuator 15 is operated by the control unit 10 to disconnect the supply unit 3 from the mains 11 under certain disconnection conditions, thereby removing any power consumption of the appliance 1.
[0023] When disconnection conditions are detected, the control unit 10 energizes the wax motor 17 by supplying a driving current ID and causes the main switch 12 to open. Once the main switch 12 has been opened, connection to mains 11 is interrupted and the driving current ID automatically ceases. Thus, the shaft 22 of the wax motor 17 returns to the retracted position and the user can manually close the main switch 12 to restart using the appliance 1. Preferably, the coupling mechanism 18 is configured so that the the main switch 12 may be manually closed even before the shaft has been brought back to the retracted position (for example, the output member 25 may disengage and return to a rest position after opening the main switch 12).
[0024] Disconnection conditions may include:
- a) a positive check that a use (washing) cycle has terminated (block 50 in figure 4); or
- b) a positive check that the appliance 1 has remained connected to the mains 11 for a threshold time T without being used (block 60, figure 5).
[0025] Condition b) may be tested based on actual power consumption of the appliance 1 or request of other quantities, such as water or steam for steam irons.
[0026] Once disconnection conditions have been detected, the wax motor 17 is energized to disconnect the supply unit 3 from mains 11 (block 55 and 65 in figures 4 and 5, respectively).
[0027] According to an alternative embodiment (figures 6 and 7), the wax motor 17 is directly and unidirectionally connected to the main switch 12. In practice, the shaft 22 of the wax motor 17 directly couples to the moving contact 26 of the main switch 12 to open the main switch 12 when the wax motor 17 is energized by the control unit 10.
[0028] Use of wax motors to controllably disconnect the supply unit of a household appliance form mains has several advantages.
[0029] First, power consumption may be completely eliminated when an appliance remains unattended after use, either in an active or a standby state. In particular, washing cycles of washers may be started or programmed with delay and executed without user's surveillance. Power is saved once the cycle is terminated even in case the user does not manually operate the main switch to remove connection to mains.
[0030] Another advantage resides in that wax motors must be energized for quite a long time to be operated, in the order of tens of seconds or minutes. Since the response of wax motors is so slow, there is no risk that opening of the main switch may be accidentally triggered by electromagnetic disturbances, such as voltage drops, spikes or power surges.
[0031] Instead, wax motors do not need power supply to return to their rest position. Thus, appropriate start conditions of appliances are automatically restored without any further power consumption, as soon as the shaft of the wax motor goes to the rest condition (either retracted, for a push-type wax motor, or extracted, for a pull-type wax motor).
[0032] Wax motors provide a quite large amount of actuating force. Hence, possible problems, for example caused by manufacturing imperfections, are normally overcome.
[0033] Unidirectional coupling of the wax motor and the main switch (either directly or through a coupling mechanism) is beneficial as well. After having opened the main switch, in fact, the wax motor may return to its rest position without affecting the main switch any longer. In case of power failure, the configuration of the main switch cannot be accidentally changed. Thus, when power supply is restored, operation of the appliance may be resumed. For example, an interrupted cycle may be terminated.
1. Power supply connection device comprising:
a supply unit (3); and
a main switch (12), for selectively connecting the supply unit (3) to electric mains (11) in a closed state;
characterized by a thermoactuator (17) operable to controllably open the main switch (12) and disconnect the supply unit (3) from electric mains (11).
2. Power supply connection device according to claim 1, further comprising a control
unit (10), configured to energize the thermoactuator (17) in response to detection
of disconnection conditions (50; 60).
3. Power supply connection device according to claim 2, wherein the disconnection conditions
(50) include a cycle of use of the electrical appliance being terminated.
4. Power supply connection device according to claim 2 or 3, wherein the control unit
(10) and the thermoactuator (17) are supplied by the supply unit (3) when the main
switch (12) is closed.
5. Power supply connection device according to any one of the foregoing claims, wherein
the thermoactuator (17) is unidirectionally coupled to the main switch (12), whereby,
in a first configuration of the thermoactuator (17), the thermoactuator (17) is coupled
to the main switch (12) and causes the main switch (12) to open and, in a second configuration
of the thermoactuator (17), coupling of the thermoactuator (17) and the man switch
(12) is released.
6. Power supply connection device according to claim 5, wherein the thermoactuator (17)
comprises a shaft (22), slidable between a first position, in which the shaft (22)
is coupled to the main switch (12) and causes the main switch (12) to open, and a
second position, in which coupling of the thermoactuator (17) and the man switch (12)
is released.
7. Power supply connection device according to any one of the foregoing claims, further
comprising a coupling mechanism (18) for coupling the thermoactuator (17) and the
main switch (12).
8. Power supply connection device according to claim 7, wherein the coupling mechanism
(18) comprises an input member (24), connected to the thermoactuator (17), and an
output member, releasably connectable to the main switch (12).
9. Power supply connection device according to claim 8, wherein the coupling mechanism
(18) is configured so that movements of the input member (24) are amplified by the
output member (25).
10. Power supply connection device according to any one of the foregoing claims, wherein
the thermoactuator (17) is directly connectable to the main switch (12).
11. Electrical appliance, comprising a power supply connection device according to any
one of the foregoing claims.