GB2436678A

GB2436678A - Safety kettle

Info

Publication number: GB2436678A
Application number: GB0606343A
Authority: GB
Inventors: Nicholas John Allen
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-29
Filing date: 2006-03-29
Publication date: 2007-10-03
Also published as: GB0606343D0

Abstract

An electrically powered liquid heating device has a spout with closure means 10 and at least one outlet 15 to vent excess pressure that can remain open when the device is properly seated on its intended support means and/or maintaining a safe and upright attitude. The outlet 15 automatically closes to seal the interior of the device, and electrical power to the device's heating element 4 is cut off, if the device is displaced or overturned. The spout closure means 10 can be opened against the bias of a spring by a slidable knob 11. The heating element can be activated and the vent outlet 15 opened by a slidable knob 12. In an alternative construction, the vent outlet can be incorporated in the spout opening. Detection of whether the device is properly in place may be by means of a spring-loaded plunger projecting from the bottom of the device for contact with the support surface, or using an electromagnet which is energised only when power is being supplied. The device may be cordless.

Description

1 2436678

SAFETY KETTLE

An electric liquid heating vessel with additional safety features designed to prevent accidental scalding.

Background 1

Domestic kettles are responsible for thousands of serious scalding accidents every year. In the UK alone, annually there are approximately 10,000 kettle scalding incidents referred to hospital A&E departments, with 570 being so injurious as to be classed as severe.' Many of the most severe injuries are to inquisitive toddlers who have reached up to a work surface and pulled the boiling contents of a kettle over themselves. The present invention is designed to prevent such accidental spillage.

A kettle with a normally closed spout is clearly desirable. However, in preventing accidental release of hot water, allowance must be made for the safe release of steam pressure. Accordingly, prior art in this area tends to depend upon the proper function of pressure relief valves. Unfortunately the design of suitable valves is problematic, and they may well introduce safety implications of their own. A particular concern is the forcible ejection of boiling water under steam pressure from such valves. If this possibility cannot be eliminated, then the entire safety intent of the invention may be undermined.

This may go some way to explaining why earlier designs do not appear to have been taken up and manufactured.

The present invention avoids these difficulties altogether by enabling continuous pressure release through an automatic steam vent that is open to the atmosphere during safe use, and then closes automatically if the kettle is dislodged from a safe attitude e.g. an upright position. Crucially, the proper function of this vent is also interlocked with the power supply so that active boiling cannot occur with the vent in the closed position.

Prior Art

A commercial search conducted by the UK patent office (SAS/P201264) on an earlier version of the embodiments described herein identified GB2 190826 (Flynn) as the closest prior art. No prior art was identified with a means to interlock steam vent opening / closure with the power supply to the heating element.

A device intended to improve safety cannot introduce the possibility of new dangers. Without a power supply interlock there are two major risks in the prior art: a risk of explosion, or, if the device is somehow able to release the excess pressure in an ad hoc way through the feathering of valves etc., a risk of the forcible ejection of boiling water under high pressure through these openings.

The search report concluded that the claimed invention was, prima fade, original and inventive.

Statement of Invention

An electrically powered liquid heating device, e.g. a kettle, coffee pot or the like, having a boiling chamber which is enclosed with the exception of a closeable liquid outlet (e.g. a spout), and an automatic steam outlet (or vent') The steam vent is held in the open position during normal and safe operation, but automatically seals should the kettle be displaced from a safe attitude or its proper seating in the upright position. Importantly, in all variants of the invention, closure of the steam vent is associated with loss of electrical power to the heating element. Furthermore, power may not subsequently be restored to the heating element unless a steam vent is open. In this way the safe venting of steam pressure is assured and the possibility of an over-pressure occurring within the boiling chamber is eliminated.

The vent action is controlled either by electromechanical means, or by the mainly mechanical solution shown in Figure 6. The electromechanical method employs an energized electromagnet to hold the vent open for as long as power is continuously being supplied to both it and the heating element, with closure upon power loss being achieved by spring or similar action.

The mechanical solution employs a protruding member on the underside of the kettle, which travels under the kettle's own weight. This travel is transferred by mechanical linkage to hold the steam vent open when the kettle is properly seated in the upright position.

(Note that the liquid and steam outlets may be combined into the same outlet and/or closure mechanism, in which case the term steam outlet' or vent' should be taken to refer to that combined outlet. If not combined, the liquid outlet is normally closed, preferably by spring or equivalent mechanical action, so that closure of the steam vent alone is sufficient to seal the boiling chamber.) Vent closure may be achieved in all cases by providing the kettle with a separable mains-powered base unit on which the device must be properly seated in order to receive its electrical supply. When the kettle is dislodged from this base unit, power is lost and the steam vent seals. Alternatively, or in combination with a base unit, various sensors may also be used individually or together to isolate the mains supply. This may be done by detecting the presence of liquid water in the vicinity of the steam vent with a water sensor; and/or by detecting a non-upright position with a tilt switch; and/or by a pressure sensor, switch or electrical contacts or the like on a lower surface of the kettle. (A pressure sensor or normally open switch on the base of the device may isolate power upon the kettle being lifted from a surface due to tilting or removal. Alternatively, electrical contacts may be used in combination with an electrically conducting plate attached to a powered base unit such that on displacement from that base unit electrical contact is broken.) Note that the usual thermostatic arrangements found in such heating devices are also likely to be present, e.g. arrangements to switch off power upon boiling, or should the device boil dry.

Advantages The kettle cannot accidentally spill hot or boiling water, thereby avoiding potentially serious injury to children (and indeed the elderly or infirm.) It may also be highly desirable for use in work places and other public spaces for health and safety reasons. Due to its continuous venting action it is able to operate at all times with negligible excess pressure inside the boiling chamber, and in addition it is safety-interlocked such that power cannot be supplied to the element when the steam vent is closed.

Description

The invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 shows an embodiment of the entire device with the steam vent incorporated into the spout aperture and an electromagnetic bolt (see Note 1 below) operating a catch mechanism.

Figure 2 shows a detail of the top of the kettle with an alternative arrangement illustrating separate spout and vent apertures.

Figure 3 shows an arrangement in which the steam vent is operated directly by the electromagnetic bolt, without use of a catch mechanism.

Figure 4 shows a simple example of an electromagnetic bolt mechanism.

Figure 5 shows an example of a steam vent mechanism operated by a static elect romag net.

Figure 6 shows a detail of a kettle employing mechanical means to open and close the vent by means of a protruding member on its lower surface.

Note 1: On electromagnetic bolts.' The term electromagnetic bolt' should be taken to be a generic term. It is being used here to describe an electromechanical mechanism employed to cause a member to move in response to an energized electromagnet such that the member is able to travel to hold open a steam vent, and then reverse its travel when the magnet is de-energized. While the bolt and solenoid mechanism is a convenient one to illustrate these embodiments, it should be borne in mind that there are numerous possible arrangements of electromagnets and electromagnetic materials that could be employed to produce the desired effect. Figure 4 shows a simple possible mechanism, which is described later, but it should be borne in mind that there are many extant mechanisms of more sophisticated design. For example, equivalent mechanisms are used in electronic locks for security doors. Electronic door locks are also extant which reverse their travel under power loss to enable, for example, the escape of employees from secure areas in the event of power failure. Such locks are termed failsafe' and the mechanisms used in the present invention may be taken to be analogous to them The Drawings With reference to Figure 1: A hinged flap 1 acts as both the spout seal and the steam vent seal, which is opened by depressing the spring loaded push button 2 (this is also the way the kettle is switched on). In the presence of an electrical supply the push switch 3 completes the mains supply circuit (see Note 2) which allows power to the heating element 4 and to the electromagnetic bolt 6 via the mains AC to low voltage DC converter 5. The energized electromagnet responds by pushing its bolt to the left to engage in the catch 7 thereby maintaining the mains circuit via the push switch 3 and holding the spout I steam vent open. On failure of electrical supply the electromagnet de-energizes, its bolt retracts, and the push button rises under spring action closing the spout seal with it.

Power loss, and consequential closure of the steam vent occurs if the kettle is unseated from its powered base unit 8. However (and this applies to all embodiments described herein), various sensors may be employed individually or in combination, whether or not the kettle is equipped with a separate powered base unit. All sensors 9 are intended to break the power supply on the mains side. In this embodiment, the sensor 9 illustrates a possible location for a water (level) sensor in the vicinity of the steam vent (see Note 3.) The sensor 9 may also be taken to represent, in this and in all embodiments described herein, any of the other sensors referred to in the statement of invention i.e. a tilt switch in any convenient location, or a pressure sensor, switch or electrical contacts on a lower surface of the kettle.

Note 2: On switches.' 1 5 All switches and sensors shown in the drawings are illustrative and should be taken to represent circuit breakers of some kind. For example, components switching the high voltage mains side of the power supply are unlikely to be realised as the simple push switches shown in the drawings. A normally closed push switch labeled with an S is also used as a generic symbol for a sensor 9 in all the drawings. Once again, this symbol is illustrative and is intended to indicate that the sensor normally permits a mains supply unless it detects an unsafe state.

Note 3: On water (level) sensors.

Tap water, due to its ionic content, has a significantly higher electrical conductivity than pure water or steam. Since the onset of a change in electrical conduction is virtually instantaneous and easy to detect, it is likely that the water sensor employed in the invention would be of the conductivity type. For the electromechanical embodiments, this rapid and reliable response to water in the vicinity of the steam vent could not only act as an important backup to whatever safety features may already be in place, but might even be employed as the primary means of isolating power. The water sensor may also be sited in an antechamber (Figure 3, 32) leading to a steam vent, so that it detects water and seals the vent in advance of the water ever reaching that vent. Notwithstanding these benefits, in all variants a water sensor is also capable of making the kettle inoperable should the user overfill it with water.

Figure 2 shows an alternative arrangement wherein the spout and vent use separate apertures (this may prove to be a simpler engineering solution than a combined spout and steam vent). There are many well-known and potential mechanisms for the spout seal, which may even be remotely operated by a trigger grip on the kettle's handle. In this embodiment it is illustrated as a sliding mechanism, with the barrier 10 running in grooves in the manner of a small sluice gate. The spout is opened manually for pouring or filling by sliding knob 11 away from the spout. Upon release the spout automatically reseals under spring action. The kettle is switched on, in the presence of an electrical supply, by sliding steam vent knob 12 attached to vent seal 19 away from the spout, uncovering steam vent hole 15 and putting spring 20 under tension. The catch 13 presses upon push switch 14, energizing the electromagnetic bolt 6 which moves up to engage behind the catch and maintain the electrical supply. Once again, electrical failure due to removal from a powered base unit if supplied, or by generic sensor 9, allows the bolt to reverse its travel and reseal the vent under the action of the spring 20. Since the spout barrier is already closed (it is only open when actively operated by the user), closure of the steam vent results in sealing of the boiling chamber against spillage.

Figure 3 works on the assumption that the travel or throw' of the magnetic bolt is sufficient to open the steam vent directly, without the need for a catch mechanism. In this embodiment the kettle need not be switched on by opening the steam vent manually, but may be activated by pressing the normally open push switch 16. This action momentarily closes the mains circuit and, in the presence of a power supply, will activate the electromagnetic bolt 6. Upon magnetization, moveable plate 17 is attracted to fixed plate 18, and the bolt moves upward to lift the vent seal 19. With moveable plate 17 and fixed plate 18 now in electrical contact, the electrical supply is maintained and the steam vent remains open. Once again, upon failure of power supply, either by displacement from a base unit, activation of the water sensor 9 (shown in position, with electrical connections as per Figure 1) or by any aforementioned generic sensor in its appropriate location also represented by 9, the electromagnet de-activates and spring 20 closes the vent. Note that water sensor 9 is sited within an antechamber 32 so that it may detect the presence of water and close the vent before water may reach that vent.

This embodiment has a number of benefits: the vertical orientation of the electromagnetic bolt is well suited to the void that is often found between the back wall of a kettle's boiling chamber and its handle. 21 is simply a protective dome covering the mechanism with a steam exit hole on top.

Figure 4 illustrates a simple example of a suitable electromechanical mechanism; in this case a mechanism of the electromagnetic bolt type. When the solenoid 22 is energized by a low voltage supply, moveable plate 17 is attracted to fixed plate 18 resulting in a bolt action motion to the left. Under power loss, the spring 20 reverses the bolt action. Note that convenient electrical contacts 24 may also be obtained from the mechanism. (It is assumed that suitable materials, e.g. soft, ferromagnetic, are used as required.) Figure 5 shows an alternative electromagnetic mechanism, in which the electromagnet 23 is static. Steam vent knob 12 attached to vent seal 19 is pulled to the right to uncover the steam vent hole 15. In the presence of an electrical supply, attractor plate 26 causes push switch 25 to make the mains circuit which energises the electromagnet and continues to hold the attractor plate in position (the attractor plate being made of a magnetically attractive, and preferably soft magnetic material.) Once again, upon failure of electrical supply through being removed from a base unit if present, and / or through isolation of the mains supply by generic sensor 9, the magnet de-energises and the vent closes under spring or equivalent action 20.

Figure 6 shows a mechanical solution to vent operation that does not require an electromagnetic mechanism. When the kettle is placed upon its powered base unit 8 protruding member 27 is pushed upwards against spring action which, via mechanical linkage 28, causes the vent seal 19 to uncover the vent hole 15. (In this example the steam is then ducted, via 31, to any convenient exit location such as the top of the kettle or the vicinity of the spout.) If the kettle is removed from or knocked off its base unit, the protruding member 27 reverses its travel and the vent re-seals under the action of the spring 20. Note that in order to receive an electrical supply to its element the kettle must be properly seated on its base unit, and that this in turn is not mechanically possible unless the steam vent is open. Thus the desired interlock is obtained by purely mechanical means. A desirable addition would be a water sensor 9 in the vicinity of the vent hole to prevent overfilling, which might otherwise allow ingress of water into the steam vent. (The water sensor is shown without wiring, but would once again be arranged to break the mains electrical supply in the presence of liquid water as in Figure 1.) The sensor 9 may again be taken to represent any generic sensor or sensors aforementioned in order to support the function of the device by isolating mains power.

In this embodiment the protruding member is located within the female cavity in the underside of the kettle. It is depressed by a male part 29 that projects from the upper surface of a powered base unit and locates into the female cavity to make electrical connection. Sited in this way the protruding member 27 is concealed and need not become proud of the base of the kettle even when extended. (Note that the design would still function satisfactorily if the protruding member were simply made proud of the kettle's base.

Nevertheless, concealment within the cavity may offer better protection and structural integrity for the mechanism, and greater aesthetic appeal.) Further embodiments: 1. An embodiment like that of Figure 6 lacking a separate base unit (i.e. a directly corded kettle) would still be feasible, although rather hard to justify. Nevertheless, it could be interlocked by ensuring that the travel of the steam vent mechanism operates a circuit breaker such that when the steam vent is closed, power to the heating element is isolated. This is illustrated in Figure 6 with the normally open push switch 33 placed in series (wiring not shown) with the power supply. In the drawing, because the steam vent is open, the switch is shown in the closed position due to part of the mechanical linkage 28 impinging upon it. In the event of closure of the steam vent, the mechanical linkage retracts, switch 33 opens and mains power to the heating element is isolated.

2. There is no objection to a hybrid device combining the benefits of a mechanical protruding member mechanism like that of Fig. 6 with the electromagnetic means of vent control described earlier. Such a hybrid would appear to be unnecessary, but is suggested here for sake of completeness

Claims

CLAIMS

1. An electrically powered liquid heating device having an enclosed heating I boiling chamber, a spout with closure means and, either incorporated into the spout closure or existing separately, at least one outlet for the venting of pressure that can remain open to the atmosphere when the device is properly seated on its intended support means and I or maintaining a safe and upright attitude, said outlet or outlets automatically closing in order to seal the boiling chamber and prevent dangerous spillage of hot liquid should the device be displaced from its proper seating or a safe attitude, the sealing of the boiling chamber being interlocked with the electricity supply to the device's heating element(s), such that electrical power cannot be provided to the heating element when the boiling chamber is in a sealed state.