Field of the invention

The present invention relates to a heating assembly for domestic or professional appliance of the type including a main body and an elongated heating element embedded therein.

Background of the invention

Heating elements are widely used in both domestic appliance, such as cooking apparatuses, and in professional appliance, e.g. professional cooking apparatuses, industrial ironing machines, and so on.

It is underlined that in the present application with "professional appliance", or "professional apparatus" it is meant an appliance or apparatus which is not designed to be used for "domestic" activities (even if theoretically it could be used also for domestic activities), but is designed specifically to be used in commercial/professional activities such as, for example, restoration activities (restaurants, pubs, hotels), public service laundry, or the like.

A cooking apparatus comprising a heating machine is e.g. disclosed in EP 197 905, relating to an apparatus for preparing food, particularly frying, including a griddle and a heat source for heating the griddle. The griddle is of a material of the compound type, with an upper layer of corrosion-resistant material, and a lower layer of a material with better heat conductivity than the material in the upper layer.

In one embodiment, three heating elements are used. The three heating elements are mounted without supports in a reflector box, which is suitably made from highly polished stainless steel sheet. The heating elements are completely surrounded by air in the reflector box, and they are all spaced from the griddle such that there is no risk of their coming into contact with it. As a further example, EP 197 905 discloses that for a griddle divided into four different zones, there are four reflector boxes, each containing three heating elements.

In an alternative embodiment the griddle is instead thereof provided with a heat source for heating the griddle from the inside.

In this embodiment, elongate electric heating elements are used as heat source, these elements being arranged in a suitable number in the lower layer of the griddle for transferring heat to it via conduction. These heating elements may be cast into the lower layer of the griddle on its production.

Even if this embodiment ensures good heat transfer, repairs are difficult to carry out since heating elements cannot be easily changed when needed. In particular, if one heating element is out of order, the device can't work, since the area of the griddle heated by this heating element can't be properly heated.

A further example is disclosed in AU 2009 202211 relating to a cooking plate comprising a base, a first cooking section and a second cooking section. The first cooking section comprises a first rib array which extends from the base and comprises a first groove array therebetween. The second cooking section comprises a second rib array which extends from the base and comprises a second groove array therebetween. The distance between the rib and/or groove of the first array is different from the distance between the rib and/or groove of the second array.

In both cases, as a consequence of failures of single heating elements the cooking surface is not uniformly heated.

Therefore, even in the case of failure or malfunction of only a single heating element, the cooking appliance is not capable of working properly without being repaired. Summary of the invention

The aim of the invention is to provide a heating assembly that overcomes the drawbacks of known appliance, in particular cooking appliances, comprising a plurality of heating elements.

Within this aim, a further object of the invention is allowing the heating assembly to work properly even in case of failure of single heating elements.

A further object is to provide a heating assembly in which the temperature on a heat exchange surface remains uniformly distributed even in case of failure of single heating elements.

Still another object of the invention is to provide a heating assembly that does not necessary require repairing in order to work properly even in case of failure or malfunction of a single heating element.

According to the invention it is provided a heating assembly for a domestic or a professional appliance comprising a main body and a plurality of heating elements embedded in the main body, the plurality of heating elements comprising at least one first heating element and at least one second heating element, the first heating element being shaped so as to define a folded section having a leading part and a trailing part;

wherein a portion of the second heating element is located between the leading part and the trailing part of the folded section defined in the first heating element.

It is to be understood that the in the heating assembly according to the invention, the second heating element is capable of compensating possible failure of the first heating element and vice- versa.

This is possible since the heating elements interweaves within the main body so that the same area of the main body is heated by both the first and the second heating element.

Therefore proper heating of a heating exchange surface of the main body is achieved even in case of failure of a single heating element.

At the same time, such arrangement of the heating elements also assures that the main body is uniformly heated even in the case of failure of a single heating element. In this manner it is not necessary to substitute or repair the heating element malfunctioning for the heating assembly to work properly.

According to a preferred embodiment, the heating assembly comprises at least three heating elements.

Preferably the first heating element and the second heating element have substantially the same heating power.

This makes it possible to easily provide heat uniformly on a heat exchange surface of the main body.

According to a preferred embodiment the heating elements are elongated shaped. In this manner the heating elements can be easily interwoven in order to cover the whole heat exchange surface of the main body. Furthermore, this allows embedding the heating elements within the main body without requiring complex manufacturing operations.

According to a further aspect of the invention, the second heating element is shaped so as to define a respective folded section. Preferably, a portion of the first heating element is located between a leading part and a trailing part of the folded section defined in the second heating element.

These features allow reducing the number of heating elements required in order to proper compensate failures in the heating elements, since the second heating elements are capable of compensating failures of the first heating elements and vice- versa.

According to a preferred embodiment, the heating assembly comprises a control unit for controlling the power supplied to the plurality of heating elements, wherein each of the heating elements can be individually controlled by the control unit.

In this manner, in case of failures or malfunctioning of single heating elements the heat can still be provided uniformity e.g. by selectively activating/deactivating specific heating elements.

Preferably, the heating assembly comprises a heat sensing device connected to the control unit so as to adjust the power supplied to each heating element according to the heat sensed.

This allows to proper compensate the loss of heat due to failures of heating elements, again assuring uniform heat distribution also in this cases.

According to a further preferred aspect, the heating elements are of the electric type, thus allowing an easy control of the heat provided by the heating elements. This also allows to easily detect heat provided by the heating elements by measuring the temperature over a heat exchange surface of the main body.

According to a further aspect, the invention also refers to a method for controlling a heating assembly for a domestic or a professional appliance comprising a main body and two or more heating elements embedded in the main body, for heating the latter, the method comprising:

for each one of the two or more heating elements detecting a physical quantity affected by the status of said heating element;

if, for one of said two or more heating elements, said detected physical quantity is different from an expected one, adjusting the power supplied to at least one of the remaining one or more heating elements.

Also according to this aspect, the heating assembly is capable of proving heat uniformly even in case of failure of single heating elements by adjusting the power supplied to the other heating elements.

Accordingly, it is not required to repair the heating assembly in order to work properly even in case of failure or malfunction of single heating elements.

It is underlined that the status of a heating element can be for example "properly working" or "out of order", switched ON or switched OFF, etc.

The status of an heating element affects one or more physical quantities, for example the electric current absorbed by the heating element, the heat produced by the latter (which in turn affects the temperature of the main body in which the heating element is embedded), etc.; these one or more physical quantities can be detected and used by the control unit to identify the status of each heating element.

If one or more of the heating elements is in a status not corresponding to the expected one (e.g. it is out of order), the physical quantity will be different from an expected one, and therefore the control unit modifies the power supplied to one or more of the remaining heating elements in order to compensate this unexpected status; for example if the temperature of a region of the main body is too low, this can mean that the heating element more close to this region is not working properly, and so the control unit can be configured in order to increase the power supplied to an heating element close to the one not properly working, so as to increase the temperature of that region.

It is underlined that the expected value of the physical quantity, which can be advantageously stored in a memory of the control unit, can be a specific value or a range of values, so that saying that the physical quantity is different from an expected one can mean that its value is different from a prefixed value, or not within a range of values (which can also be an open range, i.e. all the values higher or lower than a threshold). Preferably, the plurality of heating elements comprises at least one first heating element and at least one second heating element, the first heating element being shaped so as to define a folded section, wherein a portion of the second heating element is located between a leading part and a trailing part of the folded section defined in the first heating element.

Again, the interwoven arrangement of the heating elements allow to easily compensate for failures of single heating elements since the same area of main body is subjected to heating by both the first heating element and the portion of the second heating element located between the leading part and the trailing part of the former. Preferably, the heat provided by the heating elements is detected by measuring the temperature over the heat exchange surface. In this manner possible failures or malfunctions of any heating element can be easily detected.

According to a preferred embodiment, detecting the heat provided by the heating elements over a heat exchange surface of heating assembly comprises detecting failures or malfunctions of individual heating element. Preferably, adjusting individually the power supplied to each heating element comprises increasing the power supplied to the other heating element/s which are not subjected to failures or malfunctions.

Accordingly, compensation in case of failure uniform heating is readily and automatically achieved.

Brief description of the drawings

These and other features and advantages of the invention will be better apparent from the following description of some exemplary and non- limitative embodiments, to be read with reference to the attached drawings, wherein:

Fig. 1 is a top perspective view of a cooking appliance comprising heating assemblies according to the present invention;

Fig. 2 is a bottom perspective view of the cooking appliance comprising the heating assemblies according to the present invention shown in Fig. 1 ;

Fig. 3 is a bottom view of the cooking appliance of Fig. 1 ;

Fig. 4 is a side sectional view of the cooking appliance of Fig. 3 ;

Fig. 5 is a front sectional view of the cooking appliance of Fig. 3;

Figs. 6 and 6A are an exploded perspective view and a perspective view, respectively, of a heating assembly of the present invention;

Fig. 7 is a perspective view of the heating assembly of the present invention according to an alternative embodiment;

Fig. 8 is a perspective view of the heating assembly of Fig. 7 with a heating elements represented in phantom lines;

Fig. 9 is a bottom view of the heating assembly of Fig. 8; and

Fig. 10 is a side sectional view of the heating assembly of Fig. 9.

Detailed description of the invention

With reference initially to Fig. 1, a domestic or a professional appliance, for example a cooking assembly, such as a griddle, comprising a plurality of heating assemblies 100 according to present invention, is generally designated with the reference number 200.

Although the heating assembly of the present invention will be described in the following in connection to its use with a cooking appliance, it will be appreciated that the heating assembly according to the present invention can find application also in other domestic and professional appliances, e.g. professional ironing machine, not illustrated.

It is to be noted that within the meaning of the present invention the term domestic appliance represents any appliance designed for performing a specific operation to be used in a domestic environment. Examples of such appliance are domestic griddles, domestic clam shell cooking apparatuses, domestic hot tables and similar. Similarly, the term professional appliance indicates devices or apparatus to be used in commercial environment and, therefore, it also includes, for example, professional clam shell cooking apparatuses, professional hot tables, industrial ironing machines and other similar apparatuses.

According to the advantageous embodiment illustrated in attached figures, cooking appliance 200 can be for example a professional clam shell grill, of which only the bottom grill has been represented in attached Figures.

Cooking appliance 200 comprises a cooking surface 201 onto which food to be cooked, such as hamburgers, can be placed.

Cooking appliance 200 also preferably comprises side walls 202 delimiting the cooking surface 201. Preferably, the cooking appliance 200 further comprises an input device (or user interface), not shown in the drawings, e.g. comprising an on/off switch and a knob for regulating the temperature of the cooking surface 201.

According to a preferred embodiment, the cooking surface 201 is heated by means of a plurality of heating assemblies 100, preferably positioned below and in contact (directly, or with a thermal conducting material, e.g. thermal grease, placed therebetween) to the cooking surface 201. As it can be appreciated in Figs. 2 e 3, in the present embodiment the cooking appliance 200 preferably comprises three heating assemblies 100, positioned side by side. Anyway, any number of heating assemblies 100 (also a single one), could be provided.

With reference to Fig. 6 and 6A, an advantageous embodiment of a heating assembly 100 according to the present invention will be now described in detail. According to a preferred embodiment, the heating assembly 100 comprises a plurality (i.e. two or more) of heating elements 2, 3 embedded in a main body 1. Preferably, the heating elements 2, 3 are of the electric type, i.e. they are formed by electrical resistors operated by electric power. It will be anyhow appreciated that also different type of heating elements can be used, such as tubular elements in which a hot fluid or gas flows.

It should also be noted that the term "embedded" indicates that the heating elements 2, 3 are completely or mostly surrounded by the main body 10, clearly with the exception of connecting ends 25, 35, that projects outside the main body 10 in order to connect the heating elements 2, 3 to a power supply, e.g. by wires.

Preferably, the main body 10 is made of a thermal conducting material, such aluminium or copper, in order to efficiently transmit heat provided by the heating elements 2, 3.

According to the present advantageous embodiment, the main body 10 can be provided with recesses 12 and 13, shown for example in Fig. 6, shaped so as to house the heating elements therein. Preferably, the main body 10 further comprises a cover 11 positioned above the recesses 12, 13 and the heating elements 2, 3 in order to make the heating elements 2, 3 entirely surrounded by the main body 10. Also the cover 11 can be advantageously made by the same thermal conducting material of the rest of the main body 10.

According to an alternative embodiment, shown in Fig. 7-10, the main body 10 is cast on or over-moulded on the heating elements 2, 3, thus forming a single block (or single body) embedding the heating elements.

With reference now again to Fig. 4 and 5, according to a preferred embodiment the main body 10 comprises a heat transfer surface 11, which is preferably in thermal contact (directly, or with a thermal conducting material, e.g. thermal grease, placed therebetween) to the cooking surface 201, advantageously in thermal contact to the bottom region of said cooking surface 201, thus heating it for cooking foodstuff. As better shown in Fig. 6, according to a preferred embodiment the heating assembly of the present invention comprises at least one first heating element 2 and at least one second heating element 3. More preferably, the heating assembly 100 comprises three heating elements, two first heating elements 2, and one second heating element 3 arranged at least partially between the first ones.

According to a preferred embodiment, the heating elements 2, 3 are interwoven such that a portion 34 of the second heating element 3 is located between two different parts 21, 22 of the first heating element 2.

Preferably, to this end, the first heating element 2 is shaped so as to define a folded section 20. The portion 34 of the second heating element is thus located between a leading part 21 and a trailing part 22 of the folded section 20 defined in the first heating element 2.

According to a preferred embodiment, the heating elements 2 are elongated shaped. Preferably, the folded section 20 is curved and together with the leading part 21 and the trailing part 22 is globally U-shaped.

In this manner, the heating element 2 runs between opposed flanks of the main body 10, thus covering, together with the other heating elements, substantially the whole, or at least a big part of, the heat transfer surface 11.

According to a preferred embodiment, also the second heating elements 3 are similarly shaped.

Accordingly, the second heating element 3 is preferably shaped so as to define a respective folded section 30. In this manner, a portion 24 of the first heating element 2 can be located between a leading part 31 and a trailing part 32 of the folded section 30 defined in the second heating element 3.

Preferably, the heating elements 2 and/or 3 may comprise two folded sections 20, 30; in this advantageous embodiment, therefore, as it can be appreciated in particular from Fig. 9, the heating elements 2, 3 are overall substantially S-shaped (at least for the portion of them which is embedded within the main body 10) and interwoven each other.

As a matter of fact, as it can be noted from Figs. 5 and 10, portions 24 and 34 are advantageously disposed alternated inside the main body 10. Since portion 24 and portion 34 belongs to the first heating element 2 and to the second heating element 3, respectively, in case of failure or malfunction of a single heating element, the respective portion of the adjacent element will allow to obtain a sufficient uniform heat transfer to the cooking surface 201, or to compensate the loss of heat transferred thereto, as will be better explained in the following.

According to a preferred embodiment, the first heating element 2 and the second heating element 3 have substantially the same heating power.

It will be appreciated that in the present embodiment the first and second heating element 2 and 3 have preferably also the same shape, thus making it possible to use heating elements with the same characteristics for both heating elements.

According to a preferred embodiment, the domestic or a professional appliance, e.g. the cooking appliance 200, also comprises a control unit 4, only schematically shown in Fig. 2, for controlling the power supplied to the plurality of heating elements 2, 3. Preferably, each of the heating elements 2, 3 can be individually controlled by the control unit 4. In other words the control unit 4 is configured in such a way that it can control the status (e.g. the switch ON/OFF status, and/or the amount of electric power supplied to) of each one of the heating elements 2, 3 without having necessarily to contemporaneously performing actions on (e.g. switching ON/OFF) the others.

Always according to a preferred embodiment, the heating assembly may further comprise one or more heat sensing devices 5, e.g. one or more thermocouples, as schematically shown in Fig. 6 and 6A, preferably connected to the control unit 4, which is preferably configured in such a way to adjust the power supplied to each heating element 2, 3 according to the heat sensed.

Preferably, the heat sensing device can be formed by a temperature measuring device in contact with the heat transfer surface 11. Alternatively, the heat sensing device 5 can be formed by a device capable of measuring the power absorbed by the heating elements 2, 3. In this manner, the control unit 4 can detect that a failure or a malfunction in any heating elements 2, 3 as the heat sensing device measures a drop in the power absorbed by such heating element.

The operation of the heating assembly and its control method will be now described in detail.

During operation a physical quantity affected by the status of the heating element 2, 3 is detected for each heating element 2, 3.

According to a preferred embodiment, the physical quantity can comprise the temperature of a point or region of the main body 1 and/or the electrical current or the electrical power absorbed by the heating elements 2, 3.

More in general, the physical quantity may be chosen such that the heat provided by the heating elements 2, 3 over the heat exchange surface 11 of heating assembly 100, and accordingly transmitted to the cooking surface 201, is also affected by the such variation. It should also be noted that during normal operation of the appliance, i.e. when no failure or malfunction occurs, the temperature of a point or region of the main body 1 or the electrical current or the electrical power absorbed by the heating element 2, 3 or any other of the physical quantity as previously described, will have a predetermined value or more in general will be within a predetermined range. In other words, it will possible to determine an expected value of the detected physical quantity during normal operation of the appliance.

According to a preferred embodiment, if, for one of the heating elements 2, 3, the detected physical quantity is different from an expected value, the power supplied to at least one of the remaining one or more heating elements 2, 3 is adjusted accordingly.

If, for example, one heating element 3 has a malfunction, which can be detected for example since the electrical current it absorbs is different from an expected one, or since the temperature of a specific region of the cooking surface 201 (detected for example by a thermocouple) close to this heating element 3 is lower than expected, the power supplied to the remaining heating elements 2 is increased, in such a way that the temperature of that specific region of the cooking surface reaches the expected value, or falls within an expected range.

As a matter of fact, in case of malfunction or failure of a heating element, the heat overall produced by the assembly 100 drops, and accordingly also the heat transmitted to the heat exchange surface 11.

As previously explained, according to a preferred embodiment, failures can be detected for example by measuring the power absorbed by each heating elements and/or by measuring the temperature on the heat transfer surface 11.

In this manner a sufficient cooking temperature of the cooking surface 201 or a more uniform distribution of the temperature thereon can be achieved even in case of failure or malfunction of a single heating element, without necessarily repairing it, at least not immediately.

Therefore, this will make it possible also in such cases to achieve a proper working condition, or at least to reach a condition close thereto, for a domestic or professional appliance adopting a heating assembly operating according to the method of the present invention.

It will be also appreciated that the method previously described can be used also in heating assembly comprising in general a plurality of heating elements embedded in a main body.

In fact, even if the heating elements are not interwoven it will be still possible to at least partially compensate the loss of heat caused by the failure of a heating element by adjusting the power supplied to the others.