GB2197515A - Safety device for an iron - Google Patents

Description

1 GB2197515A 1

SPECIFICATION

Safety device for irons in general The present invention relates to a safey device for hand-operated household irons in general, which device is designed to eliminate the trouble and hazards caused by the user forgetting to disconnect the iron from the electricity supply when no longer in use.

Usually, known devices of the aforementioned type mainly comprise an inertial switch device for activating or resetting a timer, usually electronic, designed to control a relay power switch or similar for cutting off supply to the iron and activating a separate alarm mechanism. If the iron remains stationary in the horizontal position for longer than a given period of time, preferably thirty seconds, the timer runs down and, via the relay, activates the alarm and cuts off electricity supply to the heating resistor on the iron.

When, on the other hand, the iron is moved horizontally in normal operating manner, the timer is reset and, consequently, the alarm cut off and power supply restored to the resistor.

When operated normally, the iron is rarely left stationary for longer than the set thirty second interval, and, as each movement re- sets the timer, the power cut-off and alarm mechanisms remain inactive.

If, for any reason, however, the iron is left stationary for more than thirty seconds, the safety device is activated for preventing dam- age to the ironing or premises. If the iron is left stationary in the upright position on its stand, the safety device operates in the same way as for the horizontal position, but with a much longer time interval, conveniently of seven or eight minutes. Known devices of the aforementioned type involve extremely high manufacturing cost, mainly due to the employment of integrated-circuit timers powered by low-voltage d.c. current obtained by reducing, rectifying, filtering and stabilizing mains voltage, and the employment of separate elements for cutting off power supply and activating the alarm signal.

A further drawback is posed by the large number of components involved, which, in addition to increasing the size and weight of the device, also poses problems in terms of mass production.

The aim of the present invention is to over- come the aforementioned drawbacks by providing for a new technical solution whereby the power cut-off and alarm functions are conveniently performed by a single electromechanical element powered directly by the mains voltage.

A further aim of the present invention is to provide a device featuring known components, but assembled in an entirely new manner; which components are readily available, straightforward in design, easy to assemble, and few in number, for reducing the size and weight of the device.

With this aim in view, according to the present invention, there is provided a safety de- vice for irons, said device comprising first sensor means for detecting arrest of the said iron, second timing means controlled by the said first sensor means and, in turn, controlling third means having a safety switch for enabling or diabling electricity supply to a re- sistor for heating the said iron; characterised by the fact that the said first, second and third means are supplied directly with mains voltage. 80 A preferred embodiment of the present invention will be described, by way of a nonlimiting example, with reference to the accompanying drawings, in which: Figure 1 shows a block diagram of the elec- tric system on the device according to the present invention; Figure 2 shows a schematic side view of a first block in the Fig. 1 diagram; Figure 3 shows a schematic lateral section of a second block in the Fig. 1 diagram; Figure 4 shows an electric diagram of the Fig. 1 device; Figure 5 shows a front outside view in perspective of the device according to the pre- sent invention, housed inside a respective container; Figure 6 shows a side view of an iron incorporating the Fig. 5 device and in the horizontal position; Figure 7 shows a side view of the Fig. 6 iron in the upright position.

Number 1 in Fig. 1 indicates a block constituting a combined power switch and alarm mechanism; which block 1 is controlled by a timing block 2, in turn, controlled by a sensor block 3. As shown in Fig. 3, the said sensor block 3 comprises a bulb 4 formed, for example, from transparent plastic material having a suitable wall thickness 4a, and contain- ing a mercury bead 5 and three electrodes 6-7-8. When bulb 4 is stable with base -Apositioned horizontally, the slope of inner wall 5a of bulb 4 causes mercury bead 5 to close contacts 6-7 electrically.

Should the iron be inclined slightly in any direction, such closure is assured at all times by virtue of the said inner wall 5a of bulb 4 sloping in two perpendicular directions 5b and 5d (Fig. 5), i.e. both widthwise and length- wise.

When the said bulb 4 is moved horizontally and lengthwise at a fairly brisk speed, mercury bead 5 moves, by force of inertia, along bulb 4, so as to temporarily open contacts 6-7 and close contacts 7-8, after which, it returns to its original position (show by the continuous line in Fig. 3) when the movement ceases.

If, on the other hand, bulb 4 is tilted per- pendicularly, subsequent to the iron being 2 GB2197515A 2 placed in the upright position as described later on, so that base -A-, of bulb 4 is replaced by base "B", mercury bead 5 moves into position 5c shown by the dotted line, so as to open contacts 6-7 and close contacts 7- 8, and finally come to rest in the portion of bulb 4 wherein it contacts only electrode 8. Number 10 in Fig. 2 of block 1 indicates a sound- generating, switch-activating unit cornprising a solenoid 11 supplied with alternating current and having a coaxial, cylindrical core 12 of mild steel, to the top of which is screwed a threaded pin 40 projecting in adjustable manner, e.g. by 1/10 mm, from the top. To the bottom of core 12, there is fitted a square body 45 forming part of a magnetic circuit and on the top of which pivots an anchor 13 located at one end over pin 40 and fitted on the other end with a pull spring 14 secured to an appendix 46 on body 45. On the top side of the end facing pin 40, anchor 13 presents a first contact 15 facing a further fixed contact 15 connected to a terminal 42 on the device.

Contacts 15 of unit 10 are intially closed, by virtue of the pull exerted by spring 14 on anchor 13.

When solenoid 11 is supplied with alternating current, the magnetic force of core 12 attracts anchor 13 so as to open contacts 15 of unit 10.

The conflicting forces exerted by spring 14 and the alternating magnetic field combine to produce a drumming action of anchor 13 on pin 40, which drumming action presents the same frequency as the current supplying solenoid 11 and acts as an alarm signal.

Unit 10 is designed in such a manner that, as long as solenoid 11 is supplied, anchor 13 moves up and down in the immediate vicinity of core 12, so as not to interfere with contacts 15 which thus remain open.

When supply to solenoid 11 is cut off, anchor 13, which is no longer held back by the said magnetic field, is restored to its original position by spring 14, thus closing contacts 15.

By way of completion of Fig. 2, number 'I a indicates a flexible electrical connection be- tween anchor 13, which supplies respective contact 15, and terminal 41 on the device.

Number 2 in Fig. 4 indicates an electric circuit comprising a diode 20 having its anode connected to a terminal 43, and its cathode connected to resistors 21 and 22. In more detail, resistor 21 is connected, at the other end, to the positive terminal of an electrolytic condenser 23, to the electrode of a gas lamp 24, to the cathode of diode 25, and to electrode 7 of sensor 3. Resistor 22 is connected, at the other end, to electrode 6 of sensor 3. Electrode 8 of mercury sensor 3 is connected to terminal 41 via resistor 26, which terminal 41 is also connected to the negative terminal of electrolytic condenser 23.

Gas lamp 24 is connected to terminal 41 via resistor 27. The anode of diode 25 is connected, via resistor 28, to a node 30 which is connected to one terminal of photo-resistor 29, arranged in such a manner as to be [it up by gas lamp 24, and to one terminal of solenoid 11. The other terminals of solenoid 11 and photo- resistor 29 are connected to terminals 41 and 43 respectively.

When the iron is supplied with mains voltage, and consequently also the device via terminals 41 and 43, condenser 23 is initially discharged, gas lamp 24 is off, and photoresistor 29 presents a maximum resistance value. Node 30 therefore presents the same electrical potential as terminal 41, and supply is cut off to solenoid 11. As already described, in such a condition, contacts 15 are closed and power supplied to the heating resistor on the iron, which is series-connected between terminals 43 and 42 and so protected by contacts 15 which act as a safety switch.

When the iron is positioned horizontally, and bulb 4 of mercury sensor 3 positioned as shown by the continuous line in Fig. 3, electrodes 6-7 are connected electrically. Via diode 20 and resistors 21 and 22 connected parallel via electrodes 6 and 7, the positive half-waves of the mains voltage charge condenser 23 within a given time interval depending on the component ratings involved, or, conveniently, in thirty seconds.

When, at the end of this time, the voltage at the terminals of condenser 23 is sufficient for sparking gas lamp 24, the latter is acti vated and lights up photo-resistor 29, which therefore becomes conductive for supplying current to solenoid 11. At the same time, an chor 13 is drawn towards core 12 so as to open safety switch contacts 15 and so cut off supply to the heating resistor on the iron. Fur thermore, an alarm is sounded by anchor 13 drumming on pin 40 of core 12 at mains fre- quency.

Node 30, therefore, now presents the same potential as terminal 43, and the positive halfwaves, via resistor 28 and diode 25, keep condenser 23 charged so that the above con- dition remains stable.

When bulb 4 is moved horizontally and lengthwise, so as to move mercury bead 5 into position 5c shown by the dotted line, momentary contact is established between electrodes 7 and 8 so that condenser 23 is discharged via resistor 26, gas lamp 24 goes off, photo-resistor 29 returns to its original maximum resistance value, supply to solenoid 11 is cut off, and anchor 13 returns to its original position wherein contacts 15 are closed, supply is restored to the heating resistor on the iron, and the alarm is turned off.

A new timing cycle is started when bulb 4 and the iron are returned to the stationary horizontal position.

3 GB2197515A 3 Whenever contact is established between electrodes 7 and 8, during normal operation of the iron, condenser 23 is discharged and the timing cycle restarted. Consequently, if bulb 4 is moved at intervals of less than the said preset length, e.g. thirty seconds, the said timing cycle fails to be completed, and the alarm is not activated.

When bulb 4 is set upright, resting on base ---13-, mercury bead 5 first establishes contact between electrodes 7 and 8, thus discharging condenser 23, then moves into position 50 at the bottom of bulb 4, where it only contacts electrode 8.

In this condition, resistor 22 is relieved of its function of charging condenser 23, this function being performed solely by resistor 21, the rating of which determines a much longer charge time, e.g. eight minutes, after which the alarm is again sounded.

When bulb 4 is returned to the horizontal position, condenser 23 is discharged and the above operating cycle repeated.

As shown in Fig. 5, all the above blocks 1, 2 and 3 are enclosed in a compact, lightweight box 33 formed from synthetic material and having a pull-out or hinged lid 34 which also provides for optimum sealing against steam or liquid.

Number 60 in Fig. 6 indicates an iron resting horizontally and incorporating the safety device according to the present invention. The said iron 60 presents a handle 61 inside which the said box 33 housing block 1, 2 and 3 is housed horizontally. When the said iron 60 is placed horizontally, sensor 3 is also set in the horizontal position, as shown in Fig. 3. Iron 60 presents, for example, inside the body, a block 63 having two terminals, 64 and 65, for connection to the household electricity mains. Terminal 64 is connected to terminal 41 on the safety device, whereas terminal 65 is connected to the other terminal 43, and to one terminal of a heating resistor 66 housed inside the body of iron 60, and the other terminal of which is connected to terminal 42 on the safety device.

Fig. 7 shows iron 60 in the upright position.

The advantages of the safety device accord- ing to the present invention will be clear from the foregoing description. In particular, it is cheap and easy to produce, by virtue of being supplied directly with a.c. mains voltage; employs components readily available on the market; does not require two structurally distinct components for cutting off supply to the heating resistor and sounding the alarm; and is of compact size.

To those skilled in the art it will be clear that changes may be made to the embodiment of the present invention as described and illustrated herein without, however, departing from the scope of the present invention.

For example, the-electric circuit of timer 2 may be designed differently and, still being controlled by sensor 3, may control a triac for controlling supply to solenoid 11 in place of photo- resistor 29. (Gas lamp 24 is obviously dispensed with).

Claims (12)

1. A safety device for irons, said device comprising first sensor means for detecting arrest of the said iron, second timing means controlled by the said first sensor means and, in turn, controlling third means having safety switch for enabling or disabling electricity supply to a resistor for heating the said iron, characterised by the fact that the said first, second and third means are supplied directly with mains voltage.

2. A device as caimed in Claim 1, characterised by the fact that the said first means comprise an inertia] switch having a number of electrodes between which are established different connection conditions, depending on how the said iron is moved; the said electrodes constituting at least a first pair be- tween which connection is established in at least one arrest condition of the said iron, and a second pair between which connection is established when the said iron is moved; the said electrodes being connected respectively to a first circuit for activating the said timing means, and a circuit for resetting the said timing means.

3. A device as claimed in Claim 2, characterised by the fact that the said first and said second pair of electrodes share a common electrode.

4. A device as claimed in Claim 2 or 3, characterised by the fact that, in a second arrest position of the said iron, the said iner- tial switch disables connection between the said first and said second pair of electrodes, so as to enable a second circuit for activating the said timing means.

5. A device as claimed in one of the fore- going Claims from 2 to 4, characterised by the fact that the said inertia[ switch comprises a bulb in which are inserted the said electrodes and a mobile conducting element; the bottom wall of the said bulb sloping in two directions.

6. A device as claimed in one of the foregoing Claims, characterised by the fact that the said timing means comprises charging and discharging circuits with resistors and a con- denser.

7. A device as claimed in one of the foregoing Claims, characterised by the fact that the said timing means comprise final control means for controlling, in the said third means, devices for cutting off electrical supply to the said heating resistor; the said switch devices also forming a structural part of alarm means for indicating interruption of the said electrical supply.

8. A device as claimed in Claim 7, charac- 4 GB2197515A 4 terised by the fact that the said control means comprise a gas lamp connected optically to a photovariable resistance element

9. A device as claimed in Claim 7 or 8, characterised by the fact that the said switch device comprises an electromagnetic device, supply of which is controlled by the said control means, having a mobile anchor forming part of the said safety switch, and constituting a vibratory element for generating an acoustic alarm signal when the said safety switch is opened.

10. A device as claimed in one of the foregoing Claims, characterised by the fact that it is housed inside the handle of the said iron.

11. An iron, characterised by the fact that it comprises a safety device as claimed in one of the foregoing Claims.

12. A safety device for irons, and an iron comprising the said safety device, substantially as described and illustrated herein with refer ence to the accompanying drawings.

Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.