EP0841428B1 - Overheating indicator for electrical household appliance - Google Patents

Description

The present invention relates to the general technical field of household electrical heating appliances, and more particularly to devices with different distinct heating powers depending on their usage. The invention applies for example to irons, cooking appliances or wax epilators.

The present invention relates more particularly to an apparatus provided a means indicating overheating following an order or a setting route of said device, see for example EP-A-0 677 860. It is thus already known to use two thermostats adjusted to different temperatures and associated with a wired logic allowing indicate according to the state of said thermostats if the appliance is at a temperature too low or too high. Such a system presents a major drawback insofar as the use of two thermostats leads at a significant additional cost.

It is also known to use electronic regulation for application to an iron. The latter thus has a sole whose temperature is analyzed by control electronics to determine a difference between the actual temperature and a set temperature. The gap is indicated by an indicator. The disadvantage of such a system is that it is complex on the one hand, expensive on the other.

The object of the present invention is to remedy the drawbacks mentioned above and to make a simplified overheating indicator for devices household appliances, reliably and inexpensively, in component costs and Manufacturing.

Another object of the present invention aims to considerably reduce the complexity of the various elements or constituent parts of the device allowing to realize an overheating indicator.

Another object of the present invention is to provide an apparatus, having an overheating indicator to prevent misuse of said device.

The objects assigned to the present invention are achieved using a state indication device for household appliances comprising at minus one heating element whose electrical supply is controlled by a thermostat, a device for selecting a set temperature and control means to indicate that the temperature has exceeded selected setpoint, characterized in that the control means have an electrical or electronic circuit connected in parallel to the thermostat, said circuit comprising on the one hand a self-maintained system controlling a visual or audible indicator, and on the other hand a means for initiate said self-maintained system upon actuation of the selection, the assembly being deactivated by closing the thermostat.

• la figure 1 représente un schéma de branchement d'un dispositif conforme à l'invention,
• la figure 2 représente une vue schématique d'une première variante de réalisation du dispositif conforme à l'invention,
• la figure 3 représente une vue schématique d'une seconde variante de réalisation du dispositif conforme à l'invention,
• la figure 4 représente un exemple d'agencement d'un organe de sélection ou de commande dans un dispositif conforme à l'invention,
• la figure 5 représente une vue schématique d'une variante complémentaire de réalisation du dispositif conforme à l'invention.

Other characteristics and advantages of the invention will also emerge from the description which follows with reference to the appended figure, given by way of illustration and not limitation, in which:

• FIG. 1 represents a connection diagram of a device according to the invention,
• FIG. 2 represents a schematic view of a first alternative embodiment of the device according to the invention,
• FIG. 3 represents a schematic view of a second alternative embodiment of the device according to the invention,
• FIG. 4 represents an example of arrangement of a selection or control member in a device according to the invention,
• FIG. 5 represents a schematic view of an additional variant embodiment of the device according to the invention.

Figure 1 thus shows the mains power supply with the branches L, N respectively representing the phase and the neutral of the sector.

Figure 1 also shows a heating element 1 in series with a thermostat 2, the assembly being connected to the mains. Thermostat 2 and produced in a known manner and in particular with a switch 2a allowing open or close the heating element supply circuit 1 by temperature function, either of the heating element or of hot parts of the device on which it is mounted.

Thermostat 2 has a structure known per se, which allows, using a setpoint selection device, to control adequately heating element 1 and thus obtaining a temperature optimal operation of the device. The latter also includes in accordance with the invention of the control means for indicating a exceeding the selected setpoint temperature. Indeed these means include an electronic circuit 8 connected in parallel to the thermostat 2. This circuit is connected as shown for example the Figure 1, on a connection point 7a located between the heating element 1 and the thermostat 2. The electronic circuit 8 consists in particular of a system self-maintained 4 connected in series with a visual or audible indicator 3.

The self-maintained system 4 is for example made up of a thyristor 4a, which is fitted in series with the indicator 3.

The device according to the invention also includes means for initiate thyristor 4a following actuations of the selection.

Advantageously, the thyristor 4a and the indicator 3 are connected to the point 7a connection through rectifying and filtering elements 6. These thus allow the use of electrical or electronic components adapted to the voltage from these rectifying and filtering means 6. The electronic circuit 8 is therefore supplied electrically through the elements rectification and filtering 6.

The means for starting the thyristor 4a comprises a switch control 5 mechanically connected by any means to the selection member 16 and making a fugitive microswitch whose closure is synchronized with a displacement of said selection member 16.

Figure 4 shows an example of embodiment and arrangement of such fugitive microswitch relative to the selection device 16. The latter includes thus a linear cursor 18, one end 18a of which makes a rack cooperating with an adjustment wheel 2b of the thermostat 2. The adjustment wheel 2b advantageously has a serration engaging on the end 18a. A such an assembly makes it possible to transform a linear movement of the cursor 18 into rotary movement. The selection member 16 also consists of a support piece 16a for driving the cursor 18. Support piece 16 has a relative movement with respect to the cursor 18, and this against the force return spring 17. The latter allows to release the support piece 16a of the control switch 5 when the user no longer exerts pressure on said support piece 16a. The control switch 5 is indeed integral of the cursor 18 and the support piece 16a has a configuration allowing it actuate said control switch 5. So when the user moves the cursor 18, it exerts a force in the direction F, on the support piece 16a, which actuates the control switch 5. When the user releases the selection member 16, the spring 17 makes it possible to release the switch control 5 of the pressure exerted by the support piece 16a. The closure of the control switch 5 takes place only when the cursor 18 is moved according to direction F. Such an assembly consequently achieves a contact or a Fugitive microswitch.

The control switch 5 is connected to a branch of the circuit 8 using of wires 5a, 5b connected respectively to the thyristor 4a in order to initiate this last, as well as on a connection point 7b located between the indicator 3 and the rectifying and filtering elements 6. When the command 5 closes the circuit, current is supplied to thyristor 4a and allows to initiate the latter. Once started thyristor 4a conducts a current electric through the indicator 3 thus causing a sound or visual effect both that the switch 2a is in the open position. The control switch 5 preferably performs a very short or instant but sufficient closure however to prime thyristor 4a. The microswitch produced by the control switch 5 is advantageously mounted on means elastic or springs not shown in the figures, and driven by the displacement of the selection member 16, said springs being able to fill possibly the function of the spring 17.

According to an alternative embodiment of the device according to the invention, and shown in Figure 3, the connection point 7b can be connected directly by a simple short circuit on the connection point 7a, in eliminating the rectifying and filtering means 6. It suffices in this case to use components for electronic circuit 8 adapted to the voltage supplied by the sector.

The circuit 8 in this case comprises a self-maintained system constituted a relay 13, which is produced with a coil 13a driving two relay switches 14 and 15. The indicator 3 is connected to the point of connection 7b and on neutral N through the first relay switch 14. The coil 13a is connected on the one hand to neutral N and on the other hand to the point 7b, via the second relay switch 15. The switch control 5 is connected in parallel to the second relay switch 15.

An actuation of the control switch 5, even during a short time, supplies the coil 13a. The latter causes the closure of switches 14 and 15 and through this its supply from the voltage electrical outlet at connection point 7a. The supply of the coil 13a is not not interrupted by releasing the control switch 5. The self-maintained system 4 thus ensures its electrical supply, and this keep thermostat 2 open. The characteristics of relay 13 and the indicator 3 are advantageously chosen as a function of the voltage delivered at connection point 7a.

According to an alternative embodiment of the indicator device according to the invention and shown in FIG. 5, the relay 13 only comprises the first relay switch 14 connected between the coil 13a and the indicator 3, said coil 13a being connected to the neutral N and said indicator 3 being connected to connection point 7b.
Rectifying and filtering elements 6, known per se, are arranged between the connection points 7a and 7b so as to supply direct current to the indicator 3 and to the coil 13a. The control switch 5 is connected in parallel with the indicator 3 and the first relay switch 14. With a judicious choice of the characteristics of the relay 13 and of the indicator 3, the rectifying and filtering elements 6 can be eliminated and replaced by a short circuit.

According to a complementary embodiment variant of the conforming device in the invention and shown in FIG. 2, the means for starting the thyristor 4a, includes the control switch 5 capable of connecting phase L to said audit thyristor 4a, via an interface 10 to limit the current of the priming signal. The control switch 5 is connected in parallel with a branch of circuit comprising a resistor 11 and a capacitor 12. Thus, during a mains power cut, the self-maintained system is likely to memorize information relating to the state of indicator 3. In effect, when indicator 3 is activated following overheating by compared to a selected target temperature, it may be advantageous to recover the initial state of indicator 3, after a momentary cut in the mains supply, and more particularly in cases where overheating persists after the mains supply reappears. When the switch 2a of thermostat 2 remains open, a power cut or a accidental disconnection of the appliance will not affect the state of indicator 3. The reappearance of an electrical potential on phase L causes a charge of the capacitor 12 and consequently generates a current initiation through an interface 10, which is connected to thyristor 4a. The interface 10 is chosen to optimize the boot signal.

Other alternative embodiments of the electrical or electronic circuit 8 can be envisaged without departing from the scope of the present invention. The device according to the invention therefore comprises means capable of return indicator 3 to its initial operating status consecutively power supply failure. The initial state corresponds to the state of indicator 3 just before the power supply breaks. A use an appliance that is too hot can thus be avoided.

Other electronic means for storing information can also find their application in a device according to the invention.

An example of operation of the device according to the invention is described in the following. When the user turns on the device household appliance comprising such a device, the thermostat 2 via of switch 2a regulates said device thermally. When the user actuates the selection member 16 to control a temperature setpoint, for example lower than the initial regulation temperature, switch 2a opens and consequently interrupts the supply of the element heating 1.

This operating state corresponds to overheating compared to the conservation temperature. In addition, the actuation of the selection member 16 a caused the ignition of thyristor 4a, and consequently the operation of indicator 3, by at least instantaneous closing of the command 5 or microswitch. Then when the actual temperature drops below the new set temperature, switch 2a closes the heating element supply circuit 1 and short-circuits same time the electronic circuit 8. The closing of the switch 2a indicator 3 also stops or goes out. evolution thus makes it possible to indicate to the user that the device is in a operating condition with an optimal temperature and not higher than the setpoint selected. The extinction of indicator 3 therefore attests that the device is ready to use.

The device according to the present invention has an advantage unsuspected insofar as it eliminates the use of a on the one hand from systems with non-standard thermostats and on the other hand from a expensive processing electronics.

Claims (9)

1. A state-indicator device for an electrical household appliance including at least one heater element (1) powered electrically under the control of a thermostat (2), a reference temperature selector member (16), and monitoring means for indicating whether the temperature is higher than the selected reference temperature, the device being characterized in that the monitoring means comprise an electrical or electronic circuit (8) connected in parallel with the thermostat (2), said circuit (8) including firstly a self-holding system (4) controlling an audible or visible indicator (3) and secondly means for triggering said self-holding system (4) on actuation of the selector member, the monitoring means being deactivated by the thermostat (2) closing.
2. A device according to claim 1, characterized in that the electrical or electronic circuit (8) is powered via rectifier and filter elements (6).
3. A device according to claim 2, characterized in that the self-holding system (4) is constituted by a thyristor (4) which is connected in series with the indicator (3).
4. A device according to claim 1 or claim 2, characterized in that the self-holding system (4) is constituted by a relay (13), which relay has a coil (13a) controlling at least one relay switch (14, 15).
5. A device according to any one of claims 1 to 4, characterized in that the means for triggering the self-holding system (4) comprise a switch (5) mechanically connected to the selector member (16) so as to provide a transient microcontact whose closure is synchronized with displacement of said selector member (16).
6. A device according to any one of claims 1 to 5, characterized in that the circuit (8) includes means suitable for returning the indicator (3) to its initial operating state following an interruption in the electrical power supply.
7. A smoothing iron including a device according to any one of claims 1 to 5.
8. A cooking appliance including a device according to any one of claims 1 to 5.
9. A wax epilator appliance including a device according to any one of claims 1 to 5.

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