Cooking hob with rotary blade driving means and assembly comprising a cooking hob and cooking vessel with rotary blades

The cooking hob (1) has a support plate (2) made of glass or glass ceramic, a lower magnetic coupling member (5) rotatably arranged below the support plate (2), a drive motor (6) operatively connected for rotating the lower magnetic coupling member (5), and position changing means (33) for moving the lower magnetic coupling member (5) between an operative position, in which the lower magnetic coupling member (5) is close to the support plate (2) and magnetically transmits torque to an upper magnetic coupling member (54) connected to rotary blades (53) installed in a cooking vessel (50) located on the support plate (2), and an inoperative position, in which the lower magnetic coupling member (5) is far enough from the support plate (2) for not magnetically transmitting the torque.

FIELD OF THE ART

The present invention relates to a cooking hob provided with a continuous glass or glass ceramic support plate and suitable for operating with a cooking vessel provided with rotary blades, therefore the cooking hob has driving means for driving the rotary blades of the cooking vessel through the support plate. The present invention also relates to an assembly comprising a cooking hob with rotary blade driving means and a cooking vessel with rotary blades.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,549,382 describes a cooking hob provided with a support plate for supporting several cooking vessels. The support plate has several cooking areas and the cooking hob includes heating means for each cooking area and driving means aligned with one of the cooking areas. The driving means comprise a lower magnetic coupling member driven to rotate below the support plate in a position close enough to it to magnetically transmit torque to an upper magnetic coupling member attached to a stirrer located inside a cooking vessel placed in the corresponding cooking area. In one embodiment, the lower and upper magnetic coupling members include permanent magnets.

This magnetic coupling arrangement has several drawbacks. Firstly, when the user moves the vessel closer to the cooking hob, the vessel, containing the upper magnetic coupling member, is strongly attracted by the lower magnetic coupling member of the cooking hob, and this can cause the vessel to collide against the cooking hob with the risk of breaking the support plate. Secondly, the attractive force of the two lower and upper magnetic coupling members also makes removing the vessel from the cooking area of the cooking hob difficult to a large extent. Thirdly, when there is no vessel in the cooking area of the cooking hob, different kitchen utensils of a ferromagnetic nature can be involuntarily attracted towards the cooking area due to the magnetic field generated by the permanent magnets of the lower magnetic coupling member.

DISCLOSURE OF THE INVENTION

According to a first aspect, the present invention contributes to mitigating the aforementioned and other drawbacks providing a cooking hob with rotary blade driving means for driving rotary blades installed inside a cooking vessel, where the cooking hob comprises a continuous glass or glass ceramic support plate provided with a treatment area, and where said rotary blade driving means comprise a lower magnetic coupling member rotatably arranged in said treatment area below the support plate and a drive motor operatively connected for rotating said lower magnetic coupling member. The cooking hob of the present invention is characterized in that it includes activation/deactivation means for substantially activating and deactivating the magnetic field exerted by the lower magnetic coupling member through the support plate.

In one embodiment, said activation/deactivation means comprise position changing means for moving the lower magnetic coupling member between an operative position, in which the lower magnetic coupling member is close enough to the support plate to magnetically transmit torque to an upper magnetic coupling member connected to said rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an inoperative position, in which the lower magnetic coupling member is far enough from the support plate so as to not transmit said torque.

With this arrangement, when the lower magnetic coupling member is in the mentioned inoperative position far from the support plate, the attractive force between the lower and upper magnetic coupling members is very weak and the cooking vessel can be placed in and removed from the treatment area of the support plate virtually without the need for any additional force, with the same ease with which a vessel would be placed on or removed from a cooking hob without magnetic coupling. Furthermore, when the lower magnetic coupling member is in the mentioned inoperative position far from the support plate, the magnetic field in the treatment area is so weak that it does not substantially attract other kitchen utensils susceptible to being magnetically attracted.

An example of the position changing means comprises a position changing motor operatively connected for moving a moving support with respect to a base structure supporting the support plate, and the lower magnetic coupling member together with said drive motor and mechanical transmission means for transmitting movement from the drive motor to the lower magnetic coupling member are installed on said moving support. The base structure can be fixed to a board, a surface plate, a piece of furniture, etc.

In another alternative embodiment, the activation/deactivation means comprise shielding means for moving one or more shield elements between an inactive position, in which said one or more shield elements are separated from the lower magnetic coupling member to allow it to magnetically transmit torque to the upper magnetic coupling member connected to the rotary blades installed in the cooking vessel located on the treatment area of the support plate, and an active position, in which the one or more shield elements is arranged between the support plate and the lower magnetic coupling member to prevent transmitting said torque.

For example, the support plate and the lower magnetic coupling member can be supported on a base structure, and said shielding means can comprise a shielding motor operatively connected for moving the one or more shield elements parallel to the support plate inside and outside a space between the support plate and the lower magnetic coupling member.

The one or more shield elements are made of a ferromagnetic material with a high magnetic permeability, for example soft iron. Therefore, when the one or more shield elements are in the active position, the lines of magnetic force generated by the lower magnetic coupling member are closed through the one or more shield elements and substantially do not pass through the support plate, such that the attractive effect they produce in the upper side of the support plate has a null or very weak effect with respect to the vessel or other kitchen utensils. When the one or more shield elements are in the inactive position, the lines of magnetic force generated by the lower magnetic coupling member pass through the support plate and carry out the magnetic coupling with the upper magnetic coupling member of the cooking vessel placed on the treatment area of the cooking hob.

In one embodiment, the support plate is supported on the base structure by weighing means including a weight transducer in connection with an electronic control circuit, which in turn is in connection with a control panel for controlling different functions of the cooking hob, such as the operation of the rotary blade driving means and the activation/deactivation means.

The cooking hob of the present invention preferably though not necessarily comprises heating means located in relation to the treatment area below said support plate. These heating means preferably use electric power supplied through a cable connected to the mains, and the electronic control circuit in connection with the control panel is used to also control the heating means. In a preferred embodiment, the heating means comprise an induction heating device arranged around the lower magnetic coupling member at a short distance from the support plate and an electronic induction circuit for powering up said induction heating device.

The electronic control circuit optionally includes a signal receiver configured and arranged for receiving a signal sent from a signal emitter installed in said cooking vessel, and the electronic control circuit is suitable for enabling or disabling the operation of the rotary blade driving means and/or of the position changing means and/or of the heating means according to said signal received from said signal emitter.

According to a second aspect, the present invention provides an assembly comprising a cooking hob with rotary blade driving means and a cooking vessel with rotary blades, where said cooking hob comprises a continuous glass or glass ceramic support plate provided with a treatment area, and rotary blade driving means comprising a lower magnetic coupling member rotatably arranged in said treatment area below the support plate and a drive motor operatively connected for rotating said lower magnetic coupling member, and where said cooking vessel comprises a vessel wall with a bottom and an upper opening, a lid for closing said upper opening, rotary blades installed inside said vessel wall, and an upper magnetic coupling member connected to said rotary blades and arranged for facing and being located a short distance from an upper surface of said support plate when said cooking vessel is located thereon. The assembly of the present invention is characterized in that it comprises activation/deactivation means for substantially activating and deactivating the magnetic field exerted by the lower magnetic coupling member through the support plate, as described above.

The cooking vessel forming part of the assembly comprises an electronic circuit in connection with a lid position detector configured and arranged for detecting if said lid is in a correct closed position. The mentioned electronic circuit includes a signal emitter configured for wirelessly emitting a signal representative of said lid position detection, said signal being suitable for being received by a signal receiver located below the support plate.

The cooking vessel optionally further comprises a temperature detector configured and arranged for detecting a temperature in the vessel. This temperature detector is also in connection with the electronic circuit, and said signal emitter is configured for wirelessly emitting a signal representative of said temperature detection, said signal being suitable for being received by a signal receiver located below the support plate.

The cooking hob comprises a control panel connected to an electronic control circuit for controlling said rotary blade driving means and/or said position changing means and/or said heating means. This electronic control circuit includes the mentioned signal receiver, which is configured and arranged for receiving said signals sent from the signal emitter installed in the cooking vessel when it is placed on the treatment area of the support plate. The electronic control circuit is configured for enabling or disabling the operation of said rotary blade driving means and/or of said position changing means and/or of said heating means according to said signal received from said signal emitter.

In one embodiment, the cooking vessel comprises a photovoltaic cell exposed to light and connected for charging an energy storage device configured and arranged for supplying electric current to said electronic circuit and to said detectors. In another embodiment, the cooking hob comprises an energy emitter installed below the support plate, and the cooking vessel comprises an energy receiver configured and arranged for receiving energy wirelessly emitted by said energy emitter, for converting said energy received into electric current, and for supplying said electric current to said electronic circuit and to said detectors.

The cooking vessel preferably comprises a support element located at a lower level than said bottom of the vessel wall for resting on the support plate. This support element has a coefficient of friction with respect to the support plate low enough to allow sliding and self-centering of the cooking vessel in the treatment area due to the effect of said torque transmitted by the lower magnetic coupling member of the cooking hob to said upper magnetic coupling member of the vessel and high enough to prevent the cooking vessel from rotating around due to the effect of the torque in the event that the blades are locked, said support element being made of a soft enough material so as to not scratch the support plate. Nevertheless, this support element is not essential for the purpose of the present invention, and the bottom of the cooking vessel could be supported directly on the support plate.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

Firstly,FIGS. 1 and 2show a cooking hob1according to a first embodiment of the present invention, which comprises a base structure11supporting a continuous glass or glass ceramic support plate2which is provided with a treatment area4generally visually indicated on an upper surface of the support plate2, as shown inFIG. 4.FIGS. 1 and 2likewise show a cooking vessel50arranged on the mentioned treatment area4of the support plate. The cooking vessel50has rotary blades53arranged inside it and the cooking hob1comprises rotary blade driving means32capable of rotating the rotary blades53of the cooking vessel50by means of magnetic coupling through the support plate2.

The cooking hob1alone forms the object of the first aspect of the present invention, and the assembly comprising the cooking hob1and the cooking vessel50form the object of the second aspect of the present invention.

The mentioned rotary blade driving means32provided in the cooking hob1comprise a lower magnetic coupling member5arranged for rotating about a vertical shaft16centrally arranged with respect to the treatment area4below the support plate2, and a drive motor6operatively connected for rotating said lower magnetic coupling member5.

The cooking vessel50comprises a vessel wall51with a bottom56and an upper opening, a lid52for closing said upper opening, a handle59fixed to said vessel wall51, and rotary blades53installed inside the vessel wall51. The rotary blades53are supported for rotating with respect to a vertical shaft62, which passes through an opening in said bottom56and connects with an upper magnetic coupling member54arranged in an open-bottom concavity formed at the bottom56. When the cooking vessel50is placed on the support plate2, the mentioned upper magnetic coupling member54is facing and located a short distance from an upper surface of the support plate2, without coming into contact with it.

The lower and upper magnetic coupling members5,54preferably comprise respective permanent magnets arranged with their N, S poles on opposite sides of their respective rotation shafts16,62.

The cooking hob1includes activation/deactivation means for activating/deactivating the magnetic coupling, comprising position changing means33for moving the lower magnetic coupling member5between an operative position (FIG. 1), in which the lower magnetic coupling member5is close enough to the support plate2to magnetically transmit torque to the upper magnetic coupling member54connected to the rotary blades53installed in the cooking vessel50located on the treatment area4of the support plate2, and an inoperative position (FIG. 2), in which the lower magnetic coupling member5is far enough from the support plate2so as to not transmit said torque.

In the illustrated embodiment, a moving support10, which can be moved vertically with respect to the base structure11by said position changing means33, is arranged inside the base structure11. The vertical shaft16with respect to which the lower magnetic coupling member5rotates is rotatably supported on the moving support10. The lower magnetic coupling member5has a cog pulley9fixed to it, which pulley is kinetically connected by means of a cog belt8with a cog pulley7fixed to the output shaft of a drive motor6likewise supported on the moving support10. The activation of the drive motor6rotates the lower magnetic coupling member5with respect to the vertical shaft16.

The position changing means33comprise spindles12rotatably supported on the base structure11. The mentioned spindles12are coupled to corresponding nuts13fixed in housings formed in the moving support10. Each of the spindles12has a cog pulley17fixed to it. A cog belt18is installed on said cog pulleys17forcing the spindles12to rotate in unison. One of the spindles12further has a gear wheel19fixed to it, which wheel meshes with a worm screw20fixed to the output shaft of a position changing motor14supported on the base structure11.

An activation of the position changing motor14for rotating in a first direction rotates the spindles12in a first direction, and this causes an upward vertical movement of the moving support10from the inoperative position shown inFIG. 2to the operative position shown inFIG. 1, in which the lower magnetic coupling member5can rotate with respect to the vertical shaft16in a position very close to a lower surface of the support plate2without coming into contact with it, and can magnetically transmit torque provided by the drive motor6to the upper magnetic coupling member54connected to the rotary blades54inside the cooking vessel50arranged on the treatment area4of the support plate2.

Inversely, activation of the position changing motor14for rotating in a second opposite direction causes a downward vertical movement of the moving support10from the operative position shown inFIG. 1to the inoperative position shown inFIG. 2, in which the lower magnetic coupling member5is so far from the support plate2that it cannot magnetically transmit the torque to the upper magnetic coupling member54of the cooking vessel50even though the lower magnetic coupling member5is rotating with respect to the vertical shaft16and the cooking vessel50is arranged on the treatment area4of the support plate2.

As shown in the enlarged detail ofFIG. 1, the cooking vessel50preferably comprises a support element55located at a lower level than said bottom56of the vessel wall51for resting on the support plate2such that the bottom56of the cooking vessel50is very close to the upper surface of the support plate2without coming into contact with it. In the illustrated embodiment, the mentioned support element55is in the form of a perimetral ring housed in a support skirt58fixed to the vessel wall51, although it could alternatively be in another form. For example, the support element55could be in the form of three or more individual support chocks, or the cooking vessel50could have three or more individual legs, each finished with a support element55.

In any case, the support element55is made of a material which has a coefficient of friction with respect to the support plate2low enough to allow sliding and self-centering of the cooking vessel50in said treatment area4due to the effect of said torque transmitted by the lower magnetic coupling member5of the cooking hob1to said upper magnetic coupling member54, and high enough to prevent the cooking vessel50from rotating around due to the effect of the mentioned torque, for example in the event that the rotary blades32are locked. Furthermore, the material of the support element55is soft enough so as to not scratch the support plate2. Therefore, the cooking vessel50can be placed approximately on the treatment area4of the support plate2without needing to center it perfectly since the cooking vessel50will center itself when the rotary blade driving means32of the cooking hob1start operating without scratching the support plate2.

A pushbutton63movable between a locking position, in which a protrusion64formed in the pushbutton63is introduced in a hole65formed in an appendage of the lid52for locking the lid52in the closed position (FIGS. 1 and 2), and a release position, in which the protrusion64is outside the hole65allowing the lid52to be opened, is installed in the handle59of the cooking vessel50. An elastic element66, such as a spring, pushes the pushbutton63towards said locking position, and the pushbutton63can be moved manually towards the release position against the elastic force of the elastic element66.

A cooking hob1and an assembly comprising a cooking hob1and a cooking vessel50according to a second embodiment of the present invention will now be described in relation toFIGS. 3 and 4.

The cooking hob1of this second embodiment differs from that of the first embodiment only in that the activation/deactivation means for activating/deactivating the magnetic coupling here comprise shielding means28instead of the position changing means33. InFIGS. 3 and 4, the support plate2and the lower magnetic coupling member5are supported on a base structure11such that there is a small space between both. The mentioned shielding means28comprise a shielding motor23coupled to a reducer23awhich has an output shaft24connected to a shield element26by means of an arm25.

The mentioned shield element26and the arm25have a flat enough shape to be able to be moved parallel to the support plate2inside and outside said space between the support plate2and the lower magnetic coupling member5. The shield element26has a circular shape with a diameter suitable for covering the lower magnetic coupling member5and is made of a material with high magnetic permeability, such as soft iron. If, as in the example illustrated in theFIGS. 3 and 4, an induction heating device3is arranged around the lower magnetic coupling member5, the arm25is made of a diamagnetic material, such as copper, so as to not interfere with the operation of the induction heating device3.

The shielding motor23can thus be activated for moving the shield element26between an inactive position (FIG. 3), in which the shield element26is separated from the lower magnetic coupling member5to allow it to magnetically transmit torque to the upper magnetic coupling member54connected to the rotary blades53installed in the cooking vessel50located on the treatment area4of the support plate2, and an active position (FIG. 4), in which the shield element26is arranged between the support plate2and the lower magnetic coupling member5to prevent transmitting the torque.

The cooking vessel50of the second embodiment differs from that of the first embodiment only in that it does not have the support element55. Consequently, when the cooking vessel50is placed on the treatment area4of the support plate2, the bottom56of the cooking vessel50is supported directly on the support plate2, or more specifically, a layer of coating57acoating a ferromagnetic layer57of the bottom56of the cooking vessel50is supported directly on the support plate2. The mentioned ferromagnetic layer57is suitable for being heated by the induction heating device3.

It will be understood that the cooking vessels50of the first and second embodiments are interchangeable, and both can equally operate with any of the cooking hobs1of the first and second embodiments.

In both first and second embodiments, the support plate2of the cooking hob1is supported on the base structure11by weighing means38better shown inFIG. 5. The weighing means38preferably include one or more weight transducers, each formed by a deformable support15and a strain gage (not shown) associated therewith. The mentioned deformable support15has a horizontally elongated shape and is fixed at one end to the base structure11and at the other end to a column21, which in turn is fixed to a support22supporting the support plate2. The deformable part15deforms slightly according to the weight loaded on the support plate2and the strain gage emits a signal proportional to the deformation experienced by the deformable support15.

The weight transducers are in connection with the electronic control circuit10of the cooking hob1for weighing, for example, the cooking vessel50placed on the support plate2. Given that the tare of the cooking vessel50is known, the electronic control circuit10can directly provide the weight of the foods contained in the cooking vessel50.

FIG. 6shows weighing means38according to another alternative embodiment, where the support plate2is fixed to an intermediate support27on which the lower magnetic coupling member5(not shown inFIG. 6) is supported, and where said intermediate support27is supported on the base structure11by the weighing means38, which preferably include one or more weight transducers. Each weight transducer is formed by a deformable support15and a strain gage (not shown) associated therewith, where the support deformable15has one end fixed to the base structure11and another end fixed to the intermediate support27. Therefore, the magnetic attractive force between the lower and upper magnetic coupling members5,54does not alter the operation of the weighing means38.

The cooking hob1of both first and second embodiments preferably comprises heating means34located in relation to said treatment area4below said support plate2. In the illustrated embodiments, said heating means34comprise an induction heating device3in the form of a planar ring arranged around the lower magnetic coupling member5in a position adjacent to the support plate2but without coming into contact with it. An electronic induction circuit36supplied by an electrical connection to the mains37is arranged for powering up said induction heating device3. The bottom56of the cooking vessel50comprises a planar portion around the upper magnetic coupling member54with a ferromagnetic layer57suitable for being heated by the induction heating device3.

FIG. 7shows an alternative embodiment of the cooking hob1of the present invention, where the support plate2comprises several treatment areas4, A, B, C. All the treatment areas4, A, B, C are associated with corresponding heating means, which can be induction or radiation heating means, but only the treatment area4is further associated with rotary blade driving means32and position changing means33similar to those described above in relation toFIGS. 1 and 2or shielding means28similar to those described above in relation toFIGS. 3 and 4. The cooking hob1further comprises a control panel31available to a user, which is connected to an electronic supply and control circuit30for controlling the rotary blade driving means32, the position changing means33or shielding means28, and the heating means34associated with the treatment area4, as well as the heating means associated with the remaining treatment areas A, B, C. In the embodiment shown inFIG. 4, the control panel31is independent of the support plate2, although it could alternatively be integrated in the support plate2in the form of a touch screen.

Electrical supply and control means of the assembly formed by the cooking hob1and the cooking vessel50of the present invention are now described in reference toFIG. 8. The cooking hob1comprises, below the support plate2, an electronic supply and control circuit30, which is in connection with the control panel31, the rotary blade driving means32, the position changing means33or shielding means28, the weighing means38, and with an electronic induction circuit36which in turn is in connection with the induction heating device3of the heating means34. All the electric and electronic systems of the cooking hob1are supplied by a connection to the mains37.

The cooking vessel50comprises an electronic circuit40housed for example in the hollow interior of a fixing portion60of the handle59. The electronic circuit40of the vessel is in connection with a lid position detector43configured and arranged for detecting if said lid52is in a closed position. In the illustrated embodiment, the mentioned lid position detector43comprises a reed switch arranged for being activated by a magnetic field generated by a permanent magnet44housed in the lid52. Optionally, the electronic circuit40is also in connection with a temperature detector46configured and arranged for detecting a temperature in the vessel, for example a temperature in a region of the vessel wall51. The electronic circuit40includes a signal emitter45configured for wirelessly emitting a signal representative of said lid position detection and/or of said temperature detection.

In one embodiment, the electronic circuit40of the cooking vessel50has stored information relating to the vessel (type, dimensions, calibration of the temperature sensor, manufacturer, year of manufacture, etc.), and the signal emitter45, or other emitting means in connection with the electronic circuit40, are configured for wirelessly emitting a signal representative of this information package together with the remaining information when the cooking vessel50is placed on the treatment area4of the support plate2.

The electronic supply and control circuit30of the cooking hob1includes a signal receiver35configured and arranged for receiving said signal sent from the signal emitter45installed in the cooking vessel50through the support plate2. The electronic supply and control circuit30is configured for enabling or disabling the operation of the rotary blade driving means32, and/or of the position changing means33or shielding means28, and/or of the heating means34, and/or of the weighing means38according to the signal received from said signal emitter45.

For example, the electronic supply and control circuit30will not allow the rotary blade driving means32to start operating to rotate the lower magnetic coupling member5or the position changing means33or the shielding means to put the lower magnetic coupling member5in the operative situation or the shielding means28to put the shield element26in the inactive position if the signal receiver35has not received a signal representative of the lid52being correctly closed in the cooking vessel50, even though the user has given the order to start operating by means of a control panel31of the cooking hob1.

In the illustrated embodiments, the cooking vessel50comprises a photovoltaic cell41exposed to light and connected for charging an energy storage device42, such as a rechargeable battery or an ultracapacitor, for example, configured and arranged for supplying electric current to said electronic circuit40and to said detectors43,46. For example, the photovoltaic cell41is housed in a recess of the handle59and protected by a transparent cover61.

In another alternative embodiment (not shown), the cooking hob1comprises an energy emitter installed below the support plate2and the cooking vessel50comprises an energy receiver configured and arranged for receiving energy wirelessly emitted by said energy emitter, for converting said energy received into electric current, and for supplying said electric current to said electronic circuit40and to said detectors43,46.

A person skilled in that art will envisage modifications and variations from the embodiments shown and described without departing from the scope of the present invention as it is defined in the attached claims.