EP2558785B1

EP2558785B1 - Cooktop with mobile heating elements

Info

Publication number: EP2558785B1
Application number: EP11724455.8A
Authority: EP
Inventors: Stefano Palmeto; Paolo Faraldi; Rodolfo Marchetti; Antonio Semeraro
Original assignee: Whirlpool EMEA SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2010-04-13
Filing date: 2011-04-04
Publication date: 2019-06-05
Anticipated expiration: 2031-04-04
Also published as: ITTO20100292A1; WO2011128803A1; EP2558785A1

Description

[TECHNICAL FIELD]

The present invention relates to the field of cooking devices, and in particular to induction cooking tops, wherein heating elements are located underneath a pan support plate.
More in particular, the present invention relates to a cooking top according to the preamble of claim 1.

[PRIOR ART]

As known, in order to cook food cooking tops are used which comprise heating elements (e.g. gas burners, magnetic inductors, infrared lamps or electric resistors) over which the pans containing the food to be cooked are placed.
It is also known that, in order to improve the flexibility of use of cooking tops, special measures can be taken to obtain variable cooking areas.
In particular, induction cooking tops are known wherein mobile inductors are arranged underneath the cooking top. These cooking tops are equipped with sensors that detect when a pan is laid onto the cooking top and move one or more inductors underneath the pan. Cooking tops of this type are known from ES2319031A1 .
Other cooking top solutions include a thick grid of inductors (which are typically small) arranged underneath the whole pan support plate; when a pan is placed on the cooking top, the inductors located underneath the pan are turned on automatically. Cooking tops of this type are known from US2007262072A1 .
US2526476 discloses a cooking top with a support plate, heating elements sliding underneath the support plate and a user interface for controlling the heating elements, the user interface comprising rotating levers and a plurality of mobile elements that as well slide underneath the support plate. JP2003297539 discloses a cooker, in domestic kitchen, having a top plate with induction heating elements that are partially or wholly movable. JP2006230516 discloses a built-in kitchen unit having an identification circuit which identifies the mounting position of a cooking container in top plate and a movement control apparatus which moves a coil unit to the mounting position identified. JP2009011401 discloses a built-in unit for domestic kitchens, having a base which can be moved towards the detection position of a cooking container so that the cooking container can be simultaneously detected by proximity-sensor groups. JP2006110034 discloses a kitchen structure having an electromagnetic induction cooker device arranged at the counter reverse side of the kitchen structure.
One of the main drawbacks of these cooking top solutions with variably positioned and/or sized cooking areas is their control complexity. The user interface of the cooking top, in fact, is not always intuitive, and correctly adjusting the heat supplied to a pan may be difficult. In the case of cooking areas created with mobile electric heating elements, another problem to be faced is that power must be available to the elements in all of their working positions.

[OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION]

It is one object of the present invention to improve the easiness of use of cooking tops with variably shaped and/or positioned cooking areas.
It is another object of the present invention to improve the power supply and control system of the cooking top.
It is a further object of the present invention to propose alternative solutions for moving the heating elements of the cooking top.
These and other objects of the present invention are achieved through a cooking top incorporating the features set out in the appended claims, which are intended as an integral part of the present description.
One idea at the basis of the present invention is to provide a cooking top with a user interface comprising a plurality of mobile control elements underneath the pan support plate. The control elements are positioned automatically in the cooking area, so that a user can intuitively know which controls must be operated in order to control a certain cooking area.
In the invention, at least one of the mobile elements comprises a phototransistor that activates a control when it detects an environmental light variation. In this way, when the user puts a finger on the support plate, the finger darkens a corresponding phototransistor and turns on the associated control. Unlike capacitive or inductive touch interfaces, wherein the interface must be in contact with the support plate over it, this solution offers the advantage that the sliding element of the user interface can be detached from the support plate, thus avoiding any contact friction that might damage it.
In one advantageous embodiment, the elements of the user interface are mechanically coupled (e.g. mounted to the same support bracket) to inductors which are mobile as well. In this way, each mobile element of the interface is always aligned with the corresponding inductor without needing electronic control, thus proving more reliable.
Preferably, when using mobile inductors the control signals and/or the supply current for the mobile inductor and the user interface are carried by means of spiralled cables wound around a tight cable (in particular a nylon cable). This prevents the cables, which otherwise should necessarily be left loose, from becoming entangled due to the movement of multiple inductors and mobile elements of the user interface.
In one embodiment, the cooking top comprises a plurality of mobile inductors which are mounted on a single guide fitted with a rack and which are moved along said rack by respective motors that drive a gear engaged with the rack.
In another embodiment, the cooking top comprises a plurality of mobile inductors mounted on respective guides and moved each by a motor that remains stationary during the motion of the inductor; for example, the motor moves a drive belt that carries the inductor. This embodiment makes it easier to supply power to the motor, since the latter remains stationary. Further objects and advantages of the present invention will become more apparent from the following description and from the annexed drawings.

[BRIEF DESCRIPTION OF THE DRAWINGS]

Some embodiments will now be described by way of nonlimiting example with reference to the annexed drawings, wherein:

Fig. 1 is an isometric view of a cooking top according to a first embodiment of the present invention;
- Fig. 1a shows a detail of the cooking top of Fig. 1;
- Fig. 2 shows the cooking top of Fig. 1 without the pan support plate;
- Fig. 3 is a side view of the cooking top of Fig. 1;
- Fig. 4 is a plan view of the cooking top of Fig. 1;
- Fig. 5 shows a support bracket for a heating element of the cooking top of Fig. 1;
- Fig. 6 shows a table incorporating the cooking top of Fig. 1;
- Fig. 7 shows how the cooking top detects a command issued by the user.

The drawings show different aspects and embodiments of the present invention and, where appropriate, similar structures, components, materials and/or elements in the various drawings are designated by the same reference numerals.

[DETAILED DESCRIPTION OF THE INVENTION]

Fig. 1 shows a first view of a cooking top 1 according to the present invention.
The cooking top 1 comprises a frame 100 that supports various components of the cooking top, such as the heating elements and a pan support plate 101, the latter being shown sectioned in Fig. 1 to allow visibility of the underlying items. The plate 101 is made of a sufficiently rigid material to withstand the weight of pans and to ensure good energy transfer from the heating element underneath the pans. As a function of the heating elements in use, it is possible, in a per se known manner, to choose among different materials; for example, glass-ceramic materials are well suited to halogen lamps, magnetic inductors and electric resistors.
In the following example, the cooking top will be described with reference to the use of magnetic inductors, which generate a magnetic field that surrounds and heats up the pan.
In the embodiment described with reference to Figs. 1 to 4 there are four inductors 102a, 102b, 102c and 102d, one of which (102d) is not visible in Fig. 1 because it is located underneath the support plate 101, as can be seen in Fig. 2 where the support plate 101 has been removed.
In this embodiment, the cooking top 1 is intended for being integrated into the top of a table around which people can sit down to eat, as shown in Fig. 6, where the cooking top 1 is placed within the table 300, around which there are chairs 301 inserted into a suitable area under the table top.
In Figs. 1 to 4, the three inductors 102a-102c are in an idle position, whereas the inductor 102d is in a working position. The portion 1010 (not shown in Fig. 1 for clarity) of the support plate 101 above the idle positions of the inductors 102a-102d is a "cold" pan support area under which the inductors always remain off; in this area there is no pan presence detection.
Of course, in a more compact embodiment (e.g. intended for being embedded into a kitchen cabinet), the support plate 101 may be used entirely for cooking purposes, and therefore the inductors may be on even when they are in the idle position, which in Fig. 1 corresponds to the left-hand end-of-travel position.
The inductors 102a-102d are mounted on a respective bracket 103a-103d which at the opposite end houses an interface module 104a-104d.
Fig. 5 shows one embodiment of the bracket 103a.
At one end, the bracket has a support area 1030 for receiving the interface module 104a; at the opposite end there is an area with four screws 1031 to be secured to a slider 113a and two dowel pins 1032, fastened by means of nuts, protruding under the bracket 103a to allow for end-of-travel detection, as will be explained later on.
The two ends of the bracket are joined by an arm 1033 reinforced by a rib 1034 and provided with a screw 1035 for securing the inductor 102a.
At the centre of the support area 1030 there is an opening 1036 that leads to the inside of a boxed tube 1037 connected to the bracket 103a through a reinforcement bracket 1039.
The boxed tube 1037 has an opening 1038 for the cables carrying the supply current and the control signals to the inductors and to the module 104a of the user interface.
The brackets 103b-103d will not be described in detail herein because they are substantially equal to the bracket 103a. In the example of Fig. 1, the inductors slide along the same axis, but are mounted on different guides, as will be further discussed below. This involves small modifications to the bracket shape, which however will still be fitted with means for securing the interface module, the inductor and the slider, as well as with dowel pins for detecting the end-of-travel position and with the boxed tube for housing and routing the cables.
In one embodiment, the modules 104a-104d of the user interface comprise phototransistors shielded by a diaphragm that limits the light inlet cone on the phototransistor itself.
In this embodiment, the selected support plate is made of a material transparent to visible light, so that the phototransistor 1040 can detect a light variation when the user puts a finger over the light cone received by the phototransistor. This operation is shown in Fig. 7, wherein the user's finger 200 touches the support plate 101 at the light cone 1041 received by the phototransistor 1040 mounted on the interface module 104a.
The light variation caused by the user's finger causes the generation of a signal which is transmitted by the interface module 104a to the cooking top control unit 105 through connection cables 106a which, in the example of Figs. 1-4, pass through the openings 1036 and 1038 of the bracket 103a.
In one embodiment, the connection cables 106a are of the spiralled type and are wound around a central cable 107a, e.g. a nylon cable, which is kept tight by a spring-type tensioner 108a rotatably mounted around a pin 109a secured to the frame 100.
When the bracket 103a moves in order to position the inductor 102a under a pan, it drags along the cables 106a and 107a; the spring-type tensioner 108a rotates about the pin 109a as it follows the bracket motion, thus keeping the central cable 107a tight and preventing the cables of the four inductors from getting entangled.
The spiralled cables 106a are connected to the control unit through a section 1060, which must not necessarily be spiralled as well, covering the distance between the spring-type tensioner and the control unit.
A similar connection via spiralled cables is provided for the inductors 102b-102d.
By means of the spiralled cables, the control unit adjusts the inductors' power and exchanges signals with the interface module for both receiving the user's commands and sending information to signalling means provided on the interface module, such as a display, a buzzer or LEDs, the activation of which allows to supply information to the user about the inductor's operating state.
In the embodiment described herein with reference to the Figs. 1 to 4, the inductor is moved automatically underneath the cooking top by detecting the position of the pans through a strip 110 of phototransistors installed underneath the cooking top. In an alternative embodiment, the pan position can be detected through magnetic sensors (e.g. Hall effect sensors); this latter solution is to be preferred when the cooking top uses halogen lamps or electric resistors as heating elements.
When a pan is placed over a group of phototransistors of the strip 110, these generate a signal which is received by the control unit 105 via a preferably wired connection, not shown in the drawing.
Once the position of the pan(s) has been detected, the control unit 105 controls the inductors' movement.
In the embodiment shown in Figs. 1-4, each inductor is fitted with its own independent drive system.
For example, with reference to the inductor 102a, a motor 111a drives a drive belt, in particular a toothed belt, 112a which carries a slider 113a secured to the bracket 103a through the screws 1031 previously mentioned in the description of the bracket 103a.
By controlling the rotation of the motor and thus the motion of the belt, the control unit can position the inductor 102a underneath the pan detected by the phototransistors of the strip 110.
Each inductor's slide guide comprises proximity sensors 114, e.g. magnetic sensors, which detect the presence of the dowel pins 1032 protruding under the brackets 103a-103d. When the sensor detects the dowel pin of a bracket, it informs the control unit, which then stops or slows down the inductor accordingly.
In one embodiment, only two proximity sensors 114 are used: one for detecting the right-hand end-of-travel point and one for detecting the left-hand end-of-travel point.
The example of Fig. 1 uses three proximity sensors; in this case, the right-hand and left-hand sensors signal respective positions where the speed of the inductor must be reduced, so that it can more accurately reach the respective right-hand and left-hand end-of-travel points detected by the central sensor.
It is clear that many variations may be made by a man skilled in the art wanting to implement the present invention featuring an interface sliding underneath the cooking top. For example, the inductors (which in Fig. 1 slide along the same axis) may not be aligned and may slide along parallel axes.
The belts may be replaced with worm screws with a nut secured to the inductor support bracket. The motor may drive the worm screw to adjust the position of the nut, and hence of the inductor, underneath the support plate 101.
Also, the inductor drive system may use a single guide fitted with a rack. In this embodiment, each bracket 103 a-103d has a gear which engages with the rack and is driven by a motor also mounted on the bracket. Power may be supplied to the motor, for example, through the spiralled cables 106a-106d.

Claims

A cooking top (1) comprising
a pan support plate (101),
a plurality of heating elements (102a-102d) which can slide underneath said support plate, and a user interface for controlling said plurality of heating elements (102a-102d),
wherein said user interface comprises a plurality of mobile elements (104a-104d) which can slide underneath said support plate (101),
characterised in that at least one of said mobile elements (104a-104d) comprises a phototransistor (1040) adapted to detect a light variation when a finger (200) is put on said support plate (101) where said phototransistor (1040) is located.
A cooking top according to claim 1, wherein said mobile element (104a-104d) comprises a diaphragm adapted to limit the light entering said phototransistor (1040).
A cooking top according to any one of the preceding claims, further comprising at least one system for driving said heating elements, said drive system comprising at least one motor (111a) adapted to move a drive belt (112a) to which at least one heating element (102a-102d) of said plurality is constrained by means of a slider (113a).
A cooking top according to claim 1 or claim 2, further comprising at least one system for driving said heating elements, said drive system comprising at least one motor adapted to drive a gear engaged with a rack, said motor being rigidly constrained to a heating element and moving therewith.
A cooking top according to any one of the preceding claims, wherein said heating elements (102a-102d) are rigidly constrained to said mobile elements (104a-104d).
A cooking top according to any one of the preceding claims, further comprising spiralled cables (106a-106d) adapted to carry a supply current and/or data signals to said interface module and/or to a heating element, wherein said spiralled cables (106a-106d) are wound around a central cable (107a-107d) which is kept tight by a spring-type tensioner (108a-108d) pivoted to a frame (100) of said cooking top (1).
A cooking top according to any one of the preceding claims, further comprising detection means (110) adapted to detect the position of a pan on said support plate.
A cooking top according to claim 7, wherein said detection means comprise a phototransistor strip (110).
A table (300) comprising a support plate and an area for inserting chairs (301) under said support plate, characterised by comprising a cooking top (1) within said support plate, said cooking top being a cooking top (1) according to any one of the preceding claims.