Patent Description:
Cooking processes in which food is prepared for consumption are put more and more under automatic control. For automatically controlled cooking appliances, in particular cooking hobs, vibration sensors are implemented. With said sensors the cooking progress may be better monitored, particularly when using cooking liquids, with respect to temperature increase in the food and/or of the cooking liquid.

From <CIT> a method for controlling a cooking process is known, which cooking process is operated when cooking food in a cooking vessel placed on a cooking hob. A vibration sensor is arranged in the cooking hob for a detection of boiling of a cooking liquid. However, this document does not teach how to assemble said vibration sensor in order to get a best performance thereof and to get correct and unaltered measuring results.

<CIT> discloses a cooking hob comprising a boiling detection function including an acceleration or vibration sensor, specifically a micro-electromechanical system (MEMS), to detect vibrations caused by bubbles forming inside a heated substance. The vibration sensor is placed between the heating zones, so that vibrations caused by substances boiling in any of the heating zones around the vibration sensor can be detected with substantially the same sensitivity. The MEMS sensor may be mounted on a printed circuit board, which may be coupled to a glass ceramic by mechanical means such as a pin or walls.

<CIT> discloses a cooking hob, which is connected to at least two sensors that are configured for measuring a wave propagating in the cooking hob, in particular as a result of a boiling process, wherein a control unit of the cooking hob is configured to identify the position of the source of the wave based on the time-of-flight signals received by the at least two sensors.

<CIT> discloses a cooking appliance comprising a heating unit, a control unit and a sensor unit, wherein the control unit is provided for detecting an upcoming cooking condition based on the temporal course of the signal measured by the sensor unit.

<CIT> discloses an induction heating cooker, which comprises an induction heating section for heating a cooking vessel, a vibration detection section for detecting a vibration of the cooking vessel, a vibration waveform extracting section for extracting a vibration waveform of the detected vibration, and a determining section for determining a state of an object to be heated in the cooking vessel based on the vibration waveform.

It is an object of the present invention to provide a cooking appliance with at least one carrying plate and a method for assembling a vibration sensor which provide measuring results particularly well supporting automatic cooking processes.

The object is achieved for a cooking appliance with at least one carrying plate and at least one sensing means for the detection of vibrations according to the features of claim <NUM>.

A cooking appliance according to the invention comprises at least one carrying plate adapted to receive cookware placed thereon. Said cooking appliance may be a cooking hob with a top plate. The cooking appliance further comprises at least one sensing means for the detection of vibration which is generated when food to be cooked and/or cooking adjuvant inside of the cookware is heated up. The food to be cooked and/or the cooking adjuvant may be a cooking liquid. A vibration sensor is, in particular in a detachable manner, attached to the carrying plate, which may be the top plate of the cooking hob, by way of fixation means which prevent relative movement between the vibration sensor and the carrying plate, in particular in the direction towards and/or away from each other. The fixation means comprises a first rigid frame part, which is rigidly connected to the carrying plate. Particularly, the first rigid frame part is made of plastic, which may be a cost-saving solution both in relation to material costs and as serving also as electrically isolating means. The vibration sensor, or the electronic circuit board comprising the vibration sensor, respectively, is bordered on all sides by the first rigid frame part. With such kind of all-side delimitation unfavourable relative movements are yet further eliminated.

The cooking appliance may also be an oven comprising a baking tray which receives cookware placed thereon. In this alternative embodiment, the vibration sensor is attached to the baking tray for sensing vibration at or inside said cookware.

The vibration sensor may be attached to a bottom side of the carrying plate, particularly of the top plate of the cooking hob or the baking tray inside the oven. The vibration sensor is arranged preferably in a centre region of the carrying plate.

In a specific embodiment, the vibration sensor is arranged on an electronic circuit board. This may be an advantageous solution for supporting the vibration sensor in a best way to prevent a relative movement thereof.

The first rigid frame part may be circumferentially connected to the carrying plate in order to prevent its twisting during occurrence of vibrations, what also may cause negatively influencing relative movements.

Advantageously, a second rigid frame part is connected to the first rigid frame part and the vibration sensor, or particularly the electronic circuit board comprising the vibration sensor, is clamped between the first and the second rigid frame parts. Preferably the first and the second rigid frame parts are connected with each other by way of snapping means.

In a preferred embodiment, a sealing frame part is positioned between the electronic circuit board and the first rigid frame part and/or between the electronic circuit board and the second rigid frame part. The sealing frame part is preferably made of a soft and/or flexible material, e. a rubber material or silicone. With such soft and/or flexible material a further increased free of clearance assembling may be realized.

In particular, the vibration sensor and/or an electronic circuit board comprising or carrying the vibration sensor is connected to a data bus of the cooking appliance. For this purpose preferably a communication cable is used, which may be connected to any element that can receive a data bus communication signal, for example a user interface unit or a power board of the cooking appliance.

Particularly, the vibration sensor and/or an electronic circuit board comprising or carrying the vibration sensor may be connected to a control unit and/or to a user interface unit of the cooking appliance by means of a connecting cable. The connection cable may be a MACS cable or any other cable, e. a cable used for a serial or parallel bus connection.

Advantageously, the carrying plate comprises a base plate and at least one pan support placed thereon. With this, gas burners can be used on the carrying plate.

The object is achieved for a method for assembling a vibration sensor to a carrying plate of a cooking appliance according to the features of claim <NUM>.

According to a further aspect of the invention, a method for assembling a vibration sensor to a carrying plate of a cooking appliance is disclosed. Said carrying plate may be a top plate of a cooking hob. The carrying plate transmits vibration movements from a cookware to the vibration sensor. The assembly comprises the assembling steps:.

In a following assembling step, a second rigid frame part is connected to, preferably snapped into, the first rigid frame part. The vibration sensor, in particular the electronic circuit board comprising the vibration sensor, is clamped between the first and the second rigid frame parts. Preferably, the vibration sensor or the electronic circuit board, respectively, is clamped between the frame parts with a circumferential border thereof.

It is desirable to prevent any type of relative movements, but most favourably to prevent movements in the direction towards and/or away from each other.

Particularly, the vibration sensor is fitted into an electronic circuit board and, thereafter, the electronic circuit board comprising the vibration sensor is connected to the first rigid frame part. A preferred fitting method is soldering.

A preferred embodiment is characterized by a sealing frame part which is positioned between the vibration sensor or the electronic circuit board comprising the vibration sensor, respectively, and the first rigid frame part and/or between the vibration sensor or the electronic circuit board comprising the vibration sensor, respectively, and the second rigid frame part prior to the assembling step of connecting the second rigid frame part to the first rigid frame part. The sealing frame part may be connected to the vibration sensor or to the electronic circuit board comprising the vibration sensor and, in a following assembling step, the combination of sealing frame with the vibration sensor or the electronic circuit board comprising the vibration sensor is connected to or implemented into the first rigid frame part.

In a further following assembling step, a first connector of a connecting cable may be connected to the vibration sensor or to a circuitry comprising the vibration sensor and a second connector of the connecting cable may be connected to a control unit and/or to a user interface unit of the cooking appliance. The connecting cable may be attached to the carrying plate, e. by way of gluing, in order to avoid its tear-off.

The present invention will be described in further detail with reference to the drawings, in which.

According to the illustration of <FIG>, a cooking hob <NUM>, which is in this embodiment an induction cooking hob, but could also be a gas or radiant hob, comprises a top plate <NUM>, the upper side thereof facing a user of the induction cooking hob who can place cookware thereon for cooking processes. The top place <NUM> is usually composed of glass ceramic material and cooking zones are usually indicated thereon (not shown). Four cooking zones are defined by respective induction coil arrangements <NUM> positioned beneath the top plate <NUM>.

The induction coils <NUM> are powered by means of two power boards <NUM> having identical structure and comprising a number of different electric and electronic components interconnected by a circuitry. In order to provide an intensified cooling effect on power electronic components <NUM>, also integrated in the power board circuitry, a metallic cooling channel <NUM> is placed on each power board <NUM> and the power electronic components <NUM> of each power board <NUM> are attached to the outer surface of the allocated cooling channel <NUM>. The intensified cooling effect is further increased by means of a cooling fan <NUM> for each power board <NUM>, blowing cooling air into the interior of the cooling channel <NUM>.

The induction cooking hob <NUM> further comprises a user interface <NUM> for an input of control commands by the user which user interface <NUM> is attached to the bottom side of the top plate <NUM> by means of a user interface housing <NUM>. All electric and electronic components are electrically supplied from the domestic power supply by means of a power cable (not shown) which is connected to a mains terminal <NUM> inside the induction cooking hob <NUM>.

Finally, the induction cooking hob <NUM> is also equipped with a vibration sensor adapted to support a monitoring of the progress of the cooking process, especially for an automatic cooking program. Particularly cooking liquids inside of a cookware placed on the top plate <NUM> of the induction cooking hob <NUM> cause the cookware to start to vibrate at a certain temperature level, which vibration assumes a specific degree when the cooking liquid begins to boil. The start of the boiling state is sensible by said vibration sensor.

The vibration sensor is attached to the bottom surface of the top plate <NUM>, which top plate <NUM> passes on the vibration signals from the cookware to the vibration sensor. In order to provide a proper arrangement of the vibration sensor and its suitable connection to a control unit arranged in the user interface <NUM>, the sensor is arranged on a sensor printed circuit board <NUM> which also comprises connection means. For a firm and secure attachment the sensor printed circuit board <NUM> is encased by a first frame part <NUM> and a second frame part <NUM> as will be explained as follows.

With reference to <FIG>, the arrangement of the sensor printed circuit board <NUM> within the first and second frame parts <NUM>, <NUM> is described. As can be seen in <FIG>, a first frame part <NUM> is of a rectangular shape in order to receive the sensor printed circuit board <NUM>, also being shaped rectangularly. The first frame part <NUM> is made of a plastic material and comprises, in its installation position, an upper, horizontal frame portion 23a which is crossed (see <FIG>) by a vertical frame portion 23b. The vertical frame portion 23b forms an outer boundary and an inner section of the horizontal frame portion 23a provides an upper stop surface for the sensor printed circuit board <NUM> after its integration in the first frame part <NUM> (see <FIG>).

The second frame part <NUM> is also made of a plastic material and has a rectangular shape. Its outer dimensions are adapted to the inner dimensions of the vertical frame portion 23b of the first frame part <NUM> in a way that the second frame part <NUM> is arrange-able in the interior of the vertical frame portion 23b at least without substantial clearance. After arrangement of the second frame part <NUM> within the vertical frame portion 23b its upper surface provides a lower stop surface for the sensor printed circuit board. In this assembling position, upper and lower stop surfaces form a sandwich-like holding mechanism for the sensor printed circuit board <NUM>.

For a particular firm arrangement of the sensor printed circuit board <NUM> between first <NUM> and second <NUM> frame parts avoiding movements of these parts relative to each other, the sensor printed circuit board <NUM> is bordered by a sealing frame part <NUM> which is of a U-shaped cross section and encompasses the outer edge of the sensor printed circuit board <NUM> on all sides. The sealing frame part <NUM> is made of a soft and/or flexible material, like temperature-resistant rubber or silicone, and allows a tight clamping of the outer edge of sensor printed circuit board <NUM> between first <NUM> and second <NUM> frame parts. The connection of the second frame part <NUM> with the first frame part <NUM> is realized by snapping means 29a arranged at the vertical frame portion 23b and, as counterparts, by snapping means 29b arranged at the second frame part <NUM>.

<FIG> illustrates the installation situation of the arrangement of the sensor printed circuit board <NUM> between first <NUM> and second <NUM> frame parts in the induction cooking hob <NUM>. This figure shows a cross-sectional side view of a centre region of the top plate <NUM>. The sensor printed circuit board arrangement is attached to said centre region by means of gluing. An adhesive beading <NUM> between an outer section of the horizontal frame portion 23a and the bottom side of the centre region arranges for a permanent fixing of the sensor printed circuit board arrangement.

The manufacturing of the sensor printed circuit board arrangement during the assembly of the induction cooking hob <NUM> is as follows. First, the adhesive beading is applied on the bottom side of the centre region of the top plate <NUM>, followed by pressing the first frame part <NUM> against the bottom side of the top plate <NUM> until the top edge of the vertical frame portion 23b rests on the bottom surface of the top plate <NUM>. In that position, the adhesive beading is also applied on the upper surface of the outer section of the horizontal frame portion 23a, thus realizing a permanent bonded joint between first frame part <NUM> and top plate <NUM>. Only thereafter, the sensor printed circuit board <NUM> is implemented in the first frame part <NUM> and the mounting of the second frame part <NUM> finalizes the assembling. <FIG> illustrates another embodiment, in which the carrying plate/ top plate <NUM> is a system comprising a base plate 3a and at least one pan support 3b placed thereon.

Claim 1:
A cooking appliance with at least one carrying plate (<NUM>) adapted to receive cookware placed thereon, in particular a cooking hob (<NUM>) with a top plate, and at least one sensing means for the detection of vibration generated when food to be cooked and/or cooking adjuvant inside of the cookware is heated up, the food to be cooked and/or cooking adjuvant in particular being a cooking liquid, wherein a vibration sensor is, in particular detachably, attached to the carrying plate (<NUM>) by way of fixation means which prevent relative movement between the vibration sensor and the carrying plate (<NUM>), in particular in the direction towards and/or away from each other,
characterized in that
the fixation means comprise a first rigid frame part (<NUM>), particularly a plastic frame part, the first rigid frame part (<NUM>) being rigidly connected to the carrying plate (<NUM>),
wherein the vibration sensor, particularly the electronic circuit board (<NUM>) comprising the vibration sensor, is bordered on all sides by the first rigid frame part (<NUM>).