GB2344045A

GB2344045A - Electrical kettle with means to inhibit heating if over filled

Info

Publication number: GB2344045A
Application number: GB9825730A
Authority: GB
Inventors: Bernd Franzel; Hildegard Heberle
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 1997-10-10
Filing date: 1998-11-24
Publication date: 2000-05-31
Anticipated expiration: 2018-11-24
Also published as: DE19744916B4; DE19744916A1; GB2344045B; FR2769481B1; FR2769481A1; GB9825730D0

Abstract

A kettle comprises an electrically heated vessel 3, a switch system 16,17 for switching on the heating means and means for detecting filling of the vessel above a predetermined maximum level such that switching on of the heating means is inhibited in response to detection of filling above that level. The detecting means can be a float arrangement 19 carrying a blocking arm 33 which pivots into position to mechanically inhibit pushbutton 16 of the switch system when the float bell 25 rises above the predetermined maximum filling level in the vessel 3 (this level can be marked). In this position, to indicate the level of filling, there is preferably a carrier arm 27 having an integrally moulded indicator disc 29 at its upper end positioned so that the disc 29 is visible in viewing window 31 in the lid 10. Alternatively, the detecting means can comprise optical, capacitive or inductive means or, preferably, a resistive sensor (39, Fig.3), mounted at the inner wall of the vessel and connected with electronic means (53) to deliver a "switch-off" signal to a control switch (49) on exceeding of the maximum filling level. A liquid crystal display can be provided to indicate the exact filling level of the vessel 3.

Description

2344045 ELECTRICAL KETTLE WITH FILL STATE MONITORING The present invention

relates to an electric kettle.

In German patent specification DE 1 96 23 618 there is disclosed a kettle in which, for the boiling of water, a user fills a vessel and subsequently starts the heating process by actuation of a switch element. If the user has filled the vessel with water above a maximum level marking, water, which is vigorously moved during the boiling process, can spray out of a pouring spout of the vessel. On the one hand this leads to an undesired wetting of the outer surface of the kettle and, for example, of the worktop on which the kettle is placed and on the other hand the water being boiled to excess and sprayed out of the kettle represents a risk of injury for the user and, especially, children.

It would accordingly be desirable to eliminate this disadvantage.

According to the present invention there is provided an electric kettle with a heatable vessel, which is closable by means of a lid and has a 'max' marking for charactensing the maximum permissible filling quantity, with a pouring opening and a handle, and with a switch element for starting the heating process, characterised in that a filling state detector, which prevents switching-on of the kettle in the case of exceeding the maximum permissible filling quantity, is arranged in the vessel.

The filling state detector detects at least the water level in the region of the 'max' marking and in the case of overfilling of the vessel blocks, for example mechanically, the actuation of a switch element for starting the heating process or interrupts the current supply of heating means of the kettle directly after actuation of the switch element. Advantageously, the filling state detector controls an optical or acoustic signalling device by which the user is informed about the overfilling. The exact level, at which start of the heating process is to be blocked because boiling water could otherwise spray out of the vessel, can be established empirically.

In a preferred embodiment the detector is a float arrangement. This can be a constructionally very simple and reliable detector, which does without additional electronics and sensors and the function of which can be checked by the user at any time 2 without problems. The float arrangement can be removed in simple manner for cleaning of the vessel.

Alternatively, the detector can be an optical, capacitive, inductive or resistive sensor connected with a processing electronic system which controls a control switch of the kettle. In that case the heating process may be able to be started temporarily even in the overfilled state of the vessel, because the sensor or the processing electronic system has to be supplied with electrical energy in order to detect the filling state. In the event of detection of overfilling, however, the heating process can then be stopped very quickly. It would also be possible that, on actuation of a switch element of the kettle, initially only the filling state sensor and the processing electronic system thereof are connected to mains voltage and this frees or starts the heating process only if the water in the vessel is or falls below the'max' marking.

Overfilling of the vessel can be signalled particularly simply and clearly for a user if the filling state detector, or an arrangement controlled by this, mechanically blocks the switch element for starting of the heating process in the case of exceeding of the maximum permissible filling quantity.

Depending on the design of the filling state detector this can control an indicator device for the filling state of the vessel. This can be realised as a simple 'yes'Pno' statement with respect to the attainment of a specific filling quantity. However, the detector can, if appropriately constructed, control, for example, a liquid crystal display for exact indication of the instantaneous filling state.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view of a first kettle embodying the invention; Fig. 2 is a partly cutaway and sectional view, to enlarged scale, of the kettle of Fig. 1; and Fig. 3 is a block circuit diagram of an electrical circuit of a second kettle embodying the invention.

3 Referring now to the drawings there is shown a kettle I comprising a conically upwardly tapering vessel 3 of synthetic, for example plastics, material which is fillable with water and has a base 5. The base 5 is of metal and sealingly injection-moulded into the material of the wall of the vessel 3. Arranged at the underside of the base 5 is a heating element, by way of which the base and thus the water disposed in the vessel 3 is heated up. The vessel 3 is continued at its underside by an annular synthetic material support skirt 7, which is closed at its lower end portion by a circular plate-shaped base member 9 (Fig. 1). Arranged between the base 5 and the member 9 are a heating subassembly and an electrical control or regulating subassembly of the kettle 1, which control the heating and switching-off of the kettle 1.

The upwardly open vessel 3 is closable at its upper end by a removable lid 10 hinged to the vessel. A funnel-shaped pouring spout 11 is moulded onto the vessel 3 at one side and a substantially ear-shaped handle 13 is fastened to the vessel 3 at the opposite side.

A switch element 15 is retained in a housing of the kettle 1 in the lid region between the lid 10 and the handle 13 (Figs. 1 and 2). This switch element 15 comprises a substantially vertically slidably guided pushbutton 16 which, when subjected to pressure, presses or displaces downwardly a switching rod 17, which is coupled therewith, of the switch element 15. In a lower end setting of the pushbutton 16, this or the switching rod 17 connected therewith is then detented in position by detent means (not shown). On actuation of the switch element 15, the control or regulating subassembly in the chamber below the base 5 is switched or actuated in known manner. Through actuation of the pushbutton 10, as described above, the heating process is started on each occasion.

As shown in Fig. 2, a float arrangement 19 of synthetic material is hinged in the vessel 3 and comprises two hinge arms 21 of approximately quarter-circle shape arranged parallel to one another and connected with struts. The hinge arms 21 are pivotably mounted at their upper ends to a wall 23 of a steam channel of the kettle 1. A downwardly open float bell 25 is provided at the opposite ends of the arms 21. In the case of the filling state, indicated in Fig. 2, in the region of a 'max' marking on the vessel 3, the float bell 25 rises above this on the surface of the water. In this position, a carrier arm 27 fastened to the arms and having an integrally moulded indicator disc 29 at its upper end is positioned so that the disc is visible in a correspondingly shaped transparent viewing window 31 in the 4 lid 10. At the same time a blocking arm 33, which is fixedly connected with the arms 21, projects through a wall of the vessel 3 into a position below the pushbuffon 16 in the vertical travel path thereof or otherwise engages into or blocks vertical movement of the switching rod 17.

In the case of the impermissible overfilling state shown in Fig. 2, the indicator disc 29 of the float arrangement 19 signals to a user that the maximum filling state has been exceeded. In addition, the actuation of the pushbutton 16 of the switch element 15 is mechanically blocked by the blocking arm 33 of the float arrangement 19. To ensure a secure blocking, the indicator disc 29 can bear against the underside of the lid 10 on attainment of the maximum filling state. The user accordingly is not able to press the pushbutton 16 into the switch-on setting and thus to start the heating process. Only when some water has been emptied out of the vessel 3 does the float bell 25 sink down due to the reduced filling state. The blocking arm 33 then pivots out of the travel path of the pushbutton 16 and the heating process can be started by the user by actuation of the switch element 15, as described above.

In a second embodiment (Fig. 3), in departure from the first embodiment a resistance structure, which is known as such, serving as a resistive sensor element 39 is mounted at the inner wall of the vessel in the region of the 'max' marking. The element 39 consists of two small metal electrodes slightly spaced from one another. The resistance between the two electrodes is substantially infinitely large when the water is disposed below the resistance structure. If the water level reaches the two resistance elements, then the resistance between these is significantly reduced. The basic circuit diagram of Fig. 3 shows the electrical operation of the kettle with the sensor element 39 of the second embodiment in place of the float arrangement 19 of the first embodiment. In the case of the second embodiment, a heating element 41 for heating the water in the vessel 3 can be supplied with electric energy by the application of electric voltage to a supply plug 43 of the kettle. For that purpose initially a switch 45, which is to be actuated by the user, of the kettle is closed. As long as the water does not boil, the current circuit also remains closed by a temperature monitoring element 47. The circuit also includes a control switch 49, which is controlled by a sensor signal 51 of the sensor element 39. On exceeding of the maximum permissible filling quantity, the sensor element 39 delivers a "switch-off' signal to the control switch 49 with the aid of a processing electronic system 53 and the current supply of the heating element 41 is thereby interrupted. The heating process cannot be started, notwithstanding the fact that the switch 45 has been closed by the user.

The sensor 39 can also be replaced by other suitable sensor elements which allow detection of the filling state. Depending on the design of the sensor element, in addition to the simple onloff switching of the heating of the kettle an indicator device can be provided and controlled to exactly indicate to the user the actual filling state. For example, a liquid crystal display for that purpose can be provided in the region of the support skirt 7.

6

Claims

An electric kettle comprising a vessel provided with a lid, a pouring opening and a handle, heating means for heating the contents of the vessel, switching means for switching on the heating means, and detecting means for detecting filling of the vessel above a predetermined maximum level and inhibiting switching on of the heating means in response to detection of filling above that level.
2. A kettle as claimed in claim 1, wherein the vessel is provided with a marking denoting said level.
3. A kettle as claimed in claim 1 or claim 2, wherein the detecting means comprises a float arrangement.
4. A kettle as claimed in claim 1 or claim 2, wherein the detecting means comprises an optical, capacitive, inductive or resistive sensor connected with electronic means controlling the switching means.
5. A kettle as claimed in any one of the preceding claims, wherein the detecting means is arranged to inhibit the switching on by mechanically blocking an actuating element of the switching means.
6. A kettle as claimed in any one of the preceding claims, comprising indicating means controlled by the detecting means to indicate the level of filling of the vessel.
7. An electric kettle substantially as hereinbefore described with reference to the accompanying drawings.