Patent Description:
A stove guard refers to a device including sensors for measuring and sensing events within the area about a stove. The stove guard is a safety device intended to react to an excessive temperature and/or some other exceptional circumstance sensed by the sensor, with the aim of alleviating or eliminating the danger caused by this circumstance. As an example, the stove guard may cut off the supply of electricity, or some other operating power, to the stove, trigger an extinguisher and/or give an alarm, as a basis for the user to intervene in the threatening situation. The minimum requirements for the operation of stove guards are defined for Europe in Standard EN <NUM>.

The stove guard can be implemented as a completely independent device or as a system with components installed within the area of the stove and/or in the proximity thereof, irrespective of how the rest of the appliances and furniture are positioned. However, as it is common to often install a cooker fan or hood above the stove, or in immediate proximity thereof, it has been found out to be relatively practical to install at least the sensor-containing part of the stove guard in connection with the cooker fan or hood. Herein, the cooker fan refers to a device that has its own electric motor to actively guide the fumes from the stove in a desired direction, such as to the outside or, through a filter, back into the indoor air. The cooker hood refers to a device or fixture intended to extract the fumes from the stove, passively without a motorized fan. Hereafter, this disclosure briefly uses the term "cooker fan" although this term also covers the term "cooker hood", where appropriate.

Cooker fan manufacturers have the same problem as the other manufacturers of devices whose equipment and properties may show variation depending on respective needs. If all cooker fans were equipped with an integrated stove guard, the appliance would probably become too expensive for uses where no stove guard functionality is needed. On the other hand, if a cooker fan manufacturer separately produces basic models not having a stove guard and more advanced models having a stove guard, managing the model versions produced and delivered, along with the ordering, storing and transport processes related thereto, easily causes a double amount of work.

The publication <CIT> discloses a smart kitchen system which may be attached to a hood above a kitchen range. The publication <CIT>, an intermediate publication, discloses the detection of an induction type stove.

The present invention aims at providing a solution that makes it easier for a cooker fan manufacturer to manage the manufacture and delivery logistics in situation where some - but only some - of the manufactured cooker fans are equipped with a stove guard. Another objective of the invention is to allow locations initially lacking stove guards to be retrofitted with them. Another objective of the invention is to utilize the components of cooker fans and stove guards in a sensible way, in order to avoid unnecessary overlapping structures and solutions.

The objectives of the invention are achieved by providing the cooker fan with a preformed installation place to which the stove guard can connected as a separate module, and by shielding the installation place if no stove guard is installed therein.

In a first aspect, a modular stove guard arrangement is disclosed, including a stove guard unit, and as its parts, at least a outer casing and, inside the outer casing, a plurality of electronic components at least partially coupled to each other to cause the stove guard unit to carry out stove guard operations, such as measuring the state of the stove and/or of the environment thereof, expressing the measured state as parameter values, comparing the parameter values and/the development thereof with decision conditions and giving an alarm and/or powering off the stove in response to an exceptional circumstance found out in the comparison. The outer casing defines at least a mechanical connection to a host device to allow the stove guard unit to be at least mechanically included in an operating environment of the stove, such as a cooker fan or hood located above the stove or immediate proximity thereof. The outer casing defines a power supply connection for receiving, through the host device, operating power for the stove guard unit, and/or the stove guard unit comprises a location for an internal operating-power source, such as one or more accumulators or batteries.

In a second aspect, a modular stove guard arrangement is disclosed, including a cooker fan or hood and a preformed installation place thereon for a stove guard unit, in order to connect the stove guard unit, as a separate module, to the cooker fan or hood. Now, the cooker fan or hood comprises a shielding arrangement to shield the preformed installation place against the environmental conditions prevailing in the stove area and against unauthorized access in a situation where no stove guard unit is connected to the preformed installation place.

According to an embodiment, an operating-power connector is provided in the preformed installation place contains to supply electrical power to the stove guard unit installed in the preformed installation place. This results in the advantage that the stove guard unit can be featured with a great variety of functionalities, without any concerns of how to provide it with enough power to operate.

According to an embodiment, the shielding arrangement includes an electrical shield portion to shield the operating-power connector against unauthorized access. This results in the advantage that the device is safe to use even when no stove guard unit is installed in the cooker fan or hood.

According to an embodiment, the electrical shield portion includes a removable or movable lid or cap covering said operating-power connector. This results in the advantage that the device is safe to use even when no stove guard unit is installed in the cooker fan or hood, and despite this, it is uncomplicated to install the stove guard and to provide operating power thereto.

According to an embodiment, the cooker fan or hood has an arrangement to supply the operating-power connector with a mains voltage equal to the mains voltage to which the cooker fan or hood is intended to be connected for use. This results in the advantage that the electrical structure of the cooker fan or hood can be kept very simple and that the electrical interface therefrom to the stove guard is up to the well-known standards.

According to an embodiment, the stove guard unit has a power input connection and a voltage reducer coupled thereto, in order to produce, for at least some of the electronic components of the stove guard unit, a voltage lower than the mains voltage that the stove guard unit receives through power input connection. This results in the advantage that, while designing the stone guard unit, only very loose requirements are placed on the electrical interface between it and the host. Besides, exactly the voltage levels that are needed can be produced in the stove guard.

According to an embodiment, the cooker fan or hood includes a voltage reducer to supply the operating-power connector with a voltage lower than the mains voltage to which the cooker fan or hood is intended to be connected for use. This results in the advantage that it is easy to bring the electrical interface up to electrical safety regulations.

According to an embodiment, the voltage reducer is adapted to produce a voltage lower than the mains voltage in order to also power at least one electrically driven component included in the cooker fan or hood. This results in the advantage that the same voltage reducer can be used for two different purposes, with lower component and manufacturing costs.

According to an embodiment, the preformed installation place is shaped as a recess in order to accommodate the inserted stove guard unit so that it is completely enclosed by the outer surface defining the cooker fan or hood. This results in the advantage that it is more difficult for an unauthorized person to remove or damage the stove guard unit.

According to an embodiment, the preformed installation place and/or the stove guard unit includes a data-transfer connector to establish a data-transfer connection between the cooker fan or hood, or a similar host device, and the stove guard unit connected thereto. This results in the advantage that these devices can use each other's information, and, to utilize each other's user interface features, for example.

According to an embodiment, the modular stove guard arrangement comprises a stove guard unit and a cooker fan or hood of which the stove guard unit is adapted to be directly or indirectly compatible with the preformed installation place provided on the cooker fan or hood. This results in the advantage that there is a convenient installation place available for the stove guard unit. Besides, the modular arrangement makes it possible to manufacture and sell these devices separately, irrespective of whether a combination thereof is needed or whether only a cooker fan or hood without any stove guard functionalities is needed, for example.

According to an embodiment, the arrangement comprises an installation frame for the purpose of fitting the stove guard unit into the preformed installation place, the stove guard unit and the installation frame being compatible with installation frame and with the installation place, respectively. This results in the advantage that the stove guard unit can be optimally oriented, irrespective of how the installation place is positioned with respect to the monitored stove area.

According to an embodiment, there are at least two different interchangeable ways of the fitting of the installation frame into the preformed installation place and/or of the fitting of the stove guard unit into the installation frame, these different ways resulting in a different orientation of the stove guard unit from the cooker fan or hood, or the similar host device, towards the stove. This results in the advantage that only a small number of mechanical parts are needed for a variety of attachments suitable for a variety of situations.

According to the invention, the stove guard unit has sensors and a processor coupled thereto, the processor being adapted to identify the type of the stove situated in proximity to the stove guard unit, based on the measuring data provided by the sensors. This results in the advantage that the stove guard unit can be retrofitted in many different environments and is capable of automatically operating there in an appropriate way.

According to an embodiment, the processor is adapted to detect, based on the operation of the cooker fan or hood, or the similar host device, a cut-off in the supply of mains power to the cooker fan or hood, or the similar host device, and, in response to that the detected cut-off has ended, to prevent the stove situated within the range of the stove guard from overheating, at least temporarily. This results in the advantage that the stove does not start to re-heat unintentionally after the cut-off in a situation where the user is not present.

<FIG> show a stove <NUM> and the environment where it is used, including, herein, a cooker fan <NUM> installed above the stove <NUM>. Cooker fans are often installed directly above the stove but, herein, other installation options are not excluded, such as installing the cooker fan in the ceiling, on the side of the stove area or in the same countertop as the stove. In the last-mentioned installation, the cooker fan may also comprise a riser part rising, behind the stove, for example, to a given height from the countertop in order to suck the fumes from the stove into a filter provided behind the stove.

<FIG> use a modular stove guard which will be described in more detail below. It comprises a stove guard unit <NUM> which can be installed to form part of the cooker fan <NUM>. Therefore, the cooker fan <NUM> has a preformed installation place <NUM> for stove guard unit <NUM>, for the purpose of connecting the stove guard unit <NUM>, as a separate module, to the cooker fan <NUM>. Once installed in the cooker fan <NUM>, as shown in <FIG>, the stove guard unit can carry out a variety of stove guard operations, as required. As an example, it can measure the state of the stove <NUM> and/or of the environment thereof, express the measured environment as values as well as compare these parameter values and/or the development thereof with given decision conditions. If an exceptional circumstance is found out in this comparison, the stove guard unit <NUM> may give an alarm and/or cut off or restrict the operating power supplied to the stove <NUM>. In these operations, it may resort to other units belonging to the same modular stove guard unit, such as a switch unit (not shown in <FIG>) installed along the operating-power connection of the stove and controlled by the stove guard unit <NUM>, either through a wired or wireless connection. In its operation, the stove guard unit <NUM> may also utilize the functionalities of the stove <NUM> and/or cooker fan <NUM>, to cut off the power supply to the stove, by directly controlling a unit provided in the stove <NUM> itself and in charge of the internal operating power distribution, for example.

In <FIG>, the dashed lines <NUM> and <NUM> designate the primary field of view of the stove guard unit, i.e. the area most preferable for the stove guard unit to measure the state of the stove <NUM> and/or the environment thereof. The structure of the stove guard unit may determine the boundaries of the primary field of view. In addition to or instead, the stove guard unit can be constructed to allow the boundaries of its primary field of view to be adjusted by orienting the sensors of the stove guard unit and/or by moving optical limiters that set the boundaries of the field of view, for example.

<FIG> is a more detailed view of an exemplary stove guard unit <NUM> and the preformed installation place intended for it in a host device <NUM>, such as in a cooker fan. <FIG> especially shows the outer casing of the stove guard unit <NUM>, provided as a protective and supporting structure for the other parts of the stove guard unit <NUM>. The outer casing encloses a plurality of at least partly interconnected electronic components capable of causing the stove guard unit <NUM> to carry out the stove guard operations described above.

The outer casing of the stove guard unit <NUM> defines at least a mechanical connection to the host device <NUM>. That is, it is intended to at least mechanically connect the stove guard unit <NUM> to form part of the environment where the stove is used, such as to a cooker fan situated above or in immediate proximity of the stove. In the embodiment shown in <FIG>, the outer casing of the stove guard unit <NUM> also defines a power input connection <NUM> to allow the stove guard unit <NUM> to receive operating power through the host device <NUM>. In this embodiment, the power input connection is externally shaped as a plug embedded in the outer casing of the stove guard unit <NUM> and aligning with a counterpart <NUM> provided in the installation place as the stove guard unit <NUM> is installed.

In addition to or instead of the power input connection <NUM>, the stove guard unit <NUM> may have a location <NUM> for an internal operating-power source, such as one or more accumulators or batteries. The use of the internal operating-power source involves a number of advantages, such as the fact that the stove guard unit is completely independent of whether it is supplied with power by the host device or not. Another advantage is that no operating-power connection may not have to be designed and built in the stove guard unit and in the preformed installation place intended for it, with result that the structure is simpler and more inexpensive to implement and that, ideally, the stove guard unit is very uncomplicated to install. On the other hand, the use of the internal operating-power source involves less preferable features, such as that fact that the batteries and accumulator need to be replaced or charged from time to time, respectively, and the more limited amount of available power, which, in turn, may cause limitations in the implementation of the operating-power dependent functionalities of the stove guard unit.

The advantages and disadvantages of the operating-power connection shown in <FIG> are largely reversed in comparison to those of the internal operating-power source described above. The structure is slightly more expensive and more complicated to manufacture, and, while installing the stove guard unit, attention must paid to that the power input connection is correctly aligned in the preformed installation place <NUM>. On the other hand, an unlimited amount of operating-power can be available, at least if the supply thereof does not depend on the position of the on/off and other switches possibly controlling the operation of the host device <NUM>. Typically, a host device like a cooker fan is constantly plugged in even when it is temporarily turned off. Typically, the continuous power consumption of the electronics in the stove guard unit <NUM> can be reduced to a level enabling it to utilize the practically unlimited available operating power, in order to carry out, on a regular or more frequent basis, measurements which, in battery operation, only are possible occasionally or less often.

If provided with both the power input connection <NUM> and the location <NUM> for an internal operating-power source, the stove guard unit <NUM> may utilize the benefits of both these solutions. As an example, it may continue to operate by using its internal operating power source when there is no power supply through the power input connection <NUM>, during an electrical blackout or an unfinished installation, for example. If the internal operating power source is an accumulator, the stove guard unit <NUM> may charge the accumulator whenever necessary, provided that there is power available through the power input connection <NUM>.

<FIG> is a block diagram of a host device <NUM> and a stove guard unit according to an embodiment. In this embodiment, the preformed installation place included in the host device <NUM> is referred to as a module connection <NUM>. It can be used for connecting the stove guard unit <NUM>, as a separate module, to the host device <NUM>, but, following the modularity principle, it is not restricted to this purpose: if no stove guard functionality is needed in an operating environment, some other module extending the functionalities of the host device <NUM>, such as an additional source of light, data communication module or camera allowing a person who likes to cook and who is active on social media to easily share his/her cooking achievements, can be coupled to modular connection <NUM>.

The host device <NUM> shown in <FIG> includes a shielding arrangement <NUM> to shield the preformed installation place (i.e. the modular connection <NUM>) against the environmental conditions in the stove area and against unauthorized access when no stove guard unit <NUM> or other functionality-extending module is not connected thereto. The shielding arrangement <NUM> can be needed for a number of reasons. First, it shall be noted that grease fume and/or other air impurities may often occur naturally in the environment around the stove, making the surfaces that they come into contact with dirty. Therefore, at least one of the purposes of the shielding arrangement <NUM> is to prevent the preformed installation place from getting dirty. It may comprise a cover covering the entire modular connection <NUM> when nothing is installed therein. If needed, the cover can be shaped to comply with the rest of the design of the host device, to an extent that an ordinary user does not even notice that something is missing in the apparatus that he/she is using.

Second, if an operating-power connector <NUM> is provided in the preformed installation place to supply electric power to the stove guard unit <NUM> installed in the preformed installation place, or, to some other functionality-extending module, electrical safety must be considered. The shielding arrangement <NUM> may comprise an electric safety portion to shield the operating-power connector against unauthorized access. Thus, at least one of the purposes of the shielding arrangement <NUM> can be to prevent unauthorized persons from accessing, also unintentionally, any electrically conductive parts that may have a hazardous or dangerous voltage. The electric safety portion may include a lid or cap, for example, covering, in its shielding position, the operating-power connector <NUM> and being removable and/or movable in order to not (unreasonably) hinder appropriate installation of the stove guard unit <NUM>.

<FIG> also shows mechanical attachment <NUM> as a part of the module connection <NUM> and a corresponding mechanical connection to the host device, defined by the outer casing of the stove guard unit <NUM>. The mechanical attachment <NUM> in the module connection <NUM> and the mechanical connection <NUM> in the stove guard unit <NUM> refer to any parts and formations intended to keep the stove guard unit <NUM> in place and in the right position once it is coupled to the module connection <NUM>. For the mechanical attachment, interlockable formations, such as claw and notch pairs, or fasteners known per se, such as screws and most preferably threaded matching holes can be used. The attachment can also be accomplished by glue or self-adhesive tape.

According a preferred embodiment, the preformed installation place in the host device <NUM> is a recess to receive the stove guard unit intended to be coupled thereto so that it is entirely surrounded by the outer surface defining the cooker fan or hood. A tamper-proof solution like this is advantageous because it makes it less likely that an unauthorized person will try to remove the stove guard unit. For this type of attachment, most of the visible surfaces of the mechanical connection <NUM> of the stove guard unit can have a simpler and/or finish than what is normally required for the surfaces visible for a user. If the stove guard unit <NUM> is intended to be installed in the recess so that most of its surfaces cannot be seen anyway, there is not much need to invest in the esthetic design or finish of these surfaces. This may help, for its part, to keep the manufacturing costs of the stove guard unit reasonable.

<FIG> shows a power input connection <NUM> as a part of the connection <NUM> of the stove guard unit <NUM> to the host device. If the power input connection <NUM> is present, it can, of course, be used to receive operating power for the stove guard unit <NUM> through the host device <NUM>. In this case, the operating power is used for carrying out the stove guard operations <NUM>. However, one shall bear in mind that, as described above, the modular stove guard arrangement may also be implemented such that the stove guard unit <NUM> does not have an external power input connection <NUM> and/or the host device <NUM> does not have an operating-power connector <NUM> but the stove guard unit <NUM> has a location for an internal operating-power source, such as one or more accumulators or batteries.

Typically, the host device <NUM> is a device supplied with a mains voltage, the mains voltage referring to a single-phase alternating voltage, typically of <NUM> or <NUM> volts (rms), or a corresponding three-phase voltage, from an electricity distribution network to ordinary households or food production plants. <FIG> shows how an internal power-distribution unit <NUM> of the host device <NUM> receives a mains voltage and distributes, based on this, an operating power not only for the host device's own electrical operations <NUM> but also to the operating-power connector <NUM>. With regard to this, there is a variety of alternative embodiments examples of which will be explained in the following with reference to <FIG> and <FIG>.

The embodiment shown in <FIG> assumes that the host device (which is a cooker fan, for example) has a voltage reducer <NUM> to provide said operating-power connector with a voltage lower than the mains voltage to which the host device is intended to be coupled for use. Thus, in this embodiment, the stove guard unit installed in the module connection receives, from the host device, a voltage substantially lower than that received by the host device from electricity distribution network. Typically, the electrical safety regulations require the host device's mains power connection to include protective components <NUM>, such as fuses, surge voltage protectors and interference filters. According to the principle depicted in <FIG>, the mains voltage entering through the protective components <NUM> can be conducted, on one hand, to the mains-voltage operated parts of the host device, and, on the other hand, to the voltage reducer <NUM> producing one or more voltage levels lower than the mains voltage.

The voltage reducer <NUM> can be adapted to also produce the one or more voltage levels lower than the mains voltage to be internally used by the host device, that is, to drive at least one electrically driven part contained in the host device but operating on a voltage level lower than the mains voltage. These parts contained in the host device but operating on the lower voltage level may include electronic units, led lights or the like, for example. If the host device, in any case, is equipped with the voltage reducer <NUM> for needs like this, one of the lower voltage levels produced by it can be led to the operating-power connector <NUM> of the module connection, allowing the stove guard unit be supplied with operating power without any significant investments in the internal functionality of the host device.

In this specification, the term "extra-low voltage" refers to a voltage in a range which carries a low risk to humans. Definitions of a safe extra-low voltage can be found in standards, the most known of them being SELV standard EN <NUM>. SELV is the abbreviation of Safety Extra Low Voltage although the letter S is also claimed to stand for "separated". Leading a voltage not higher than the SELV level to the operating-power connector <NUM> results in the advantage that the structural and operational requirements set by the electricity safety regulations for the module connection <NUM> of the host device <NUM> are easier to meet than in case that the operating-power connector <NUM> receives a higher voltage.

<FIG> shows an alternative embodiment where the host device includes an arrangement for providing the operating-power connector with a mains voltage as high as than the mains voltage to which the host device is intended to be coupled for use. Thus, in this embodiment, the stove guard unit installed in the module connection receives, from the host device, exactly the same voltage as that received directly from the electricity distribution network. The mains connection of the host device may include, also in this case, protective components <NUM> but they do not cause significant changes to the voltage level, for the needs of neither the internal parts of the host device nor the stove guard unit. Because this host device can be a very simple cooker hood representing the most inexpensive product series of a manufacturer and not having, as such, any other electrical parts but a light bulb, for example, the manufacturer may not be motivated to equip it with a voltage reducer.

The electricity safety regulations may also require the stove guard unit to contain protective components <NUM>. As it is unlikely that the functionalities of the stove guard unit, at least not all of them, can be implemented as mains voltage operated, in this embodiment, a voltage reducer <NUM> is coupled to the power input connection of the stove guard unit, to produce, for at least some of the electronic components of the stove guard unit, a voltage lower than the mains voltage received by the stove guard unit through said power input connection.

The different conversions between the mains voltage and the voltage levels required by the electronic components being based on technologies known per se, the way they are carried out in detail are not dealt with in detail herein.

The mechanical attachment and the supply of operating power are not necessarily the only ways of utilizing the connection between the host device and the stove guard unit. <FIG> shows an embodiment where both the preformed installation place in the host device (i.e. the module connection <NUM>) and the stove guard unit are provided with a data-transfer connector <NUM>, <NUM> to establish a data-transfer connection between the host device and the stove guard unit connected thereto. Naturally, embodiments where this connector only is provided on one of the devices are feasible - this does not allow for the data transfer but either of the devices can be initially equipped for operation more complicated than that it eventually, when installed, is capable of under the circumstances.

The data-transfer connector <NUM> or <NUM> can be a conductive contact connector of its own or consist of one or more pins on the same physical connector that also is used for supplying the operating power to the stove guard unit. The data-transfer connector <NUM> or <NUM> may also exist in concept only (but not physically), as a connector of its own, for example, in an embodiment where the data to be transferred is modulated, as a higher-frequency signal, on top of the operating power, both the data and the operating power being physically carried along the very same paths. The data-transfer connector <NUM> or <NUM> can also be a contactless connector, such an inductive or capacitive data-transfer connection or some other wireless short-range data-transfer arrangement. The data-transfer connector can also be present or used in embodiments where no operating power is received from the host device by the stove guard unit but it is powered by an internal operating-power source. Therefore, an embodiment where the stove guard unit and the host device, despite lacking an arrangement for supplying operating power from the host device to the stove guard unit, comprise intercompatible means to implement a data-transfer interface between them.

If the option for data transfer between the stove guard unit and the host device exists, it can be utilized in a number of ways. As an example, a user interface provided on the host device is utilized to operate the stove guard unit. Let us assume that the host device is a cooker fan and the stove guard unit is installed in the rear of the lower surface thereof, in proximity to the backwall. In this solution, the user may find it difficult if he/she, every time that he/she wants to acknowledge an alarm or control the operation of the stove guard unit in some other way, for example, has to reach out in order to be able to press a button provided on the stove guard unit. Reaching out to a user interface provided on the stove guard unit may even be impossible for short or physically challenged persons. It is much more convenient if the user can carry out any necessary button presses or other user operations by means of switches provided on the front panel of the cooker fan itself. Likewise, if the cooker fan has a display, the stove guard can utilize it to present information to the user, instead of the user having to bend down under the cooker fan in order to able to see the information on the stove guard's display. This type of solutions can be implemented by causing the cooker fan and the stove guard unit installed therein to communicate over a data-transfer interface in a way suitably implementable in practice by a person skilled in the art, without providing further details herein.

<FIG> shows a few alternatives for how to position the preformed installation place intended for the stove guard <NUM> in the cooker fan <NUM>. When positioned in proximity to the front edge of the cooker fan <NUM>, the preformed installation place provides the advantage that, if the user needs to access the visible press buttons or other user interface features in order to be able to operate the stove guard unit, they are within easy reach for the user. Even in cases where a data-transfer connection can be established between the stove guard unit and the cooker fan and the user can utilize the user interface of the cooker fan, this position can be advantageous because the establishment of the connection does not require laying long wires within the structure of the cooker fan <NUM>. On the other hand, many cooker fans are designed in such a way that their parts that are visible and closest to the user are as small and gracefully shaped as possible, resulting in that it can be difficult to find enough space in the front portion of the cooker fan, at least for an installation where the stove guard unit <NUM> is accommodated in a recess, entirely inside the outer surface defining the cooker fan.

When provided centrally in the cooker fan <NUM>, the installation place provides the advantage that it is rather easy to extend the field of view of the stove guard unit installed therein to cover the entire monitoring area on the stove and everywhere around it. This also allows the differences in distance between the sensors of the stove guard unit and the closest and farthest points within the monitoring area to be relatively short, possibly making the operation of the stove guard unit operate as reliable as possible because the differences in distance only cause slight variations in the thermal radiation measured in the different directions. However, in many cases, there often is quite a large filter area in the center of the cooker fan where it can be hard to find a good installation spot for the preformed installation space. This position is especially challenging in cooker fans with a pull-out front because the ability of the stove guard unit to clearly view the monitoring area varies greatly depending on whether the front is in its inserted or pulled-out position.

When positioned in the rear edge of the cooker fan, or in proximity thereto, the preformed installation place <NUM> provides the advantage that it often is rather easy to find a space large enough for installing the stove guard unit in this area. However, as stated above, a drawback related to this installation place is that it can be difficult to access during use.

In addition to the position of the preformed installation place, it can be of great importance how it is designed, in order to allow the stove guard unit be oriented, in best way possible, towards the area to be monitored. <FIG> shows two examples where the preformed installation place <NUM> provided in proximity to the front edge of the cooker fan <NUM> is designed to direct the stove guard unit installed therein slightly in a direction away from the user (assuming that the user normally is positioned right in front of the stove). Correspondingly, the preformed installation place <NUM> provided in the rear end, or in proximity thereto, is designed to direct the stove guard unit installed therein slightly in a direction towards the user. Both these examples assume that the field of view of the stove guard unit installed in the recess, which is substantially rectangular in cross-section, is oriented, from the open side of the recess, in a direction the centerline of which is perpendicular to the bottom of the recess.

Instead of the above-described direct compatibility, the stove guard unit can also be correctly oriented by making it indirectly compatible with the preformed installation place. "Indirect compatibility" refers to that the stove guard unit is compatible with the preformed installation place through an adapter of some kind.

<FIG> show an illustrative example of this. In the embodiment depicted in these figures, the stove guard unit <NUM> is rectangular in cross-section. If the preformed installation place provided in the host device, such as the cooker fan <NUM>, is initially correctly oriented, just like the installation place <NUM> in <FIG>, the stove guard unit <NUM> can be adapted to be directly compatible with the preformed installation place. Herein, "compatibility" refers to mechanical compatibility such that, for example, inserting the stove guard unit deep enough into the recess serving as the preformed installation place causes the mechanical connecting means provided on the stove guard unit to be coupled to a mechanical connection provided in the installation place.

In the embodiment shown in <FIG>, the second possible installation place <NUM> is basically oriented similarly to the first one, but it is provided so far in the rear end of the cooker fan that the field of view of a stove guard unit installed therein and viewing straight downwards is too focused on the rear of the stove. The arrangement comprises a separate installation frame <NUM> for fitting the stove guard unit <NUM> into this preformed rear-end installation place. The stove guard unit <NUM> and the installation frame <NUM> are adapted to be compatible with the installation frame <NUM> and the preformed installation place <NUM>, respectively.

The use of the installation frame offers a variety of alternatives for the orientation of the stove guard unit. When viewing <FIG>, a preformed installation place where the stove guard unit most preferably is slightly directed away from the user, just like in the installation place <NUM> shown in <FIG>, can be imagined to exist in the front edge of the cooker fan (that is, when viewing the Figure, in the right edge of the lateral view of the cooker fan). However, this installation place can be also be oriented straight downwards, just like the preformed installation places <NUM> and <NUM>. For appropriate positioning of the stove guard unit located in the very front of the cooker fan, the installation frame <NUM> only needs to be oppositely oriented, compared to the position shown in <FIG>.

The principle described above can be generalized by defining that the fitting of the installation frame into the preformed installation place, and/or the fitting of the stove guard unit into the installation frame, can be switched between at least two different ways, these different ways resulting in different orientations of the stove guard unit towards the stove from the cooker fan or hood or the similar host device.

<FIG> is a block diagram of the parts of a stove guard unit according to a preferred embodiment for carrying out the actual stove guard operations. The stove guard unit according to <FIG> has sensors <NUM> and a processor <NUM> coupled thereto.

As a preferable feature, the processor <NUM> is adapted to identify, based on measuring data provided by the sensors <NUM>, the type of the stove placed in proximity to the stove guard unit. In practice, this can be accomplished in a number of ways. As an example, the sensors <NUM> include an electromagnetic field sensor. The operation of an induction stove is based on electromagnetic fields inducing, in the bottom of a cooking vessel, an electric current that heats up the bottom of the cooking vessel through the resistance that it encounters. These electromagnetic fields have an intensity and intrinsic behavior (and, in addition, a concurrency with the heating detected by the other sensors) making them detectable and identifiable by the electromagnetic sensor included in the stove guard unit. This allows the stove guard unit to at least recognize if the stove in its proximity is an induction stove. A similar identification can be performed by using a microphone because the use of an induction stove causes a very distinctive buzz noise. If the sensors <NUM> include a microphone and the processor <NUM> is suitably programmed to analyze the noise recorded by it, it may detect the presence of an induction stove based on this.

Another example of how the type of the stove can be identified based on measuring data provided by sensors is the use of radiation receivers operating in different wavelength ranges. A cast-iron plate stove and a ceramic stove differ in use in that the ceramic stove produces an easily detectable visible light in the red end of the spectrum, especially when there is no cooking vessel on a switched-on plate of the ceramic stove but the stove guard unit has a direct visual contact with the plate. If the stove guard unit has optical sensors operating in appropriate wavelength ranges, it may distinguish a ceramic stove from an electric plate stove based on this.

Stove type identification is useful in situations where, for example, simple cooker fans which do not have any stove guard functionalities but which, however, have a preformed stove guard unit installation place for connecting a stove guard unit to the cooker fan, as a separate module, have previously been put on the market. A buyer who has bought a cooker fan like this may later have a desire to diversify his/her kitchen and improve the fire safety of his/her house by buying a stove guard. If the stove guard unit described above is bought afterwards and installed in an arbitrary operating environment, as a rule, it does not have any information on the type of the stove. However, it should preferably be able to identify the type of the stove, at least with an accuracy of if it is an induction stove or not, because there are stove guard operations that should be carried out for induction stoves in a different way than for other stove types.

In the embodiment according to <FIG>, the processes that the processor <NUM> is programmed to execute include, in addition to stove type identification,.

As an example of the last-mentioned functionality, the processor <NUM> can be adapted to make observations on the operation of the cooker fan or the similar host device and to detect, based on this action, a cutoffs in the mains power received by the cooker fan or the similar host device from an electricity distribution network. In response to that the detected cut-off has ended, the processor <NUM> can be adapted to prevent the stove situated within the range of the stove guard unit from overheating, at least temporarily. The underlying idea is that it is possible that the electric stove is in a switched-on state when the cut-off starts, and, it is possible that its operating switches are mechanical and, therefore, it started to re-heat up the respective plates of the stove with the same power which they are set to at the start of the power cut-off. This should be prevented because it is not sure at all that the user is at the stove, or even in the house, at the end of the power cut-off.

<FIG> show a preferable way for continuously monitoring the mains power (and, possibly, for implementing some other kind of data transfer between the host device and the stove guard unit). As shown in <FIG>, the preformed installation place in the host device is a recess <NUM> having a power cord <NUM> of the host device running through a portion thereof. The stove guard unit has a portion <NUM> fittable into the recess and having built-in current sensors <NUM>. They are coupled to the processor of the stove guard unit which is capable of determining, based on the measuring data provided by the current sensors <NUM>, when there is a current running in the mains power connection of the host device, or even the magnitude of the current currently running therein.

The embodiment shown in <FIG> can be adapted to support data transfer other than the continuous monitoring of the mains power by, for example, programming the host device, which desires to communicate data to the stove guard unit, to modulate these data into a higher frequency component and to allow it to momentarily travel in its mains power connection. The current sensors <NUM> of the stove guard unit detect this higher frequency component and its variations, the processor being capable of reading the desired data therefrom.

The stove guard unit can be capable of detecting a power cut-off as such, without the arrangement shown in <FIG>. In an exemplary situation, the stove guard unit receives all of its operating power from the host device. Therefore, a power cut-off causes a shut-down of the stove guard unit as well although it normally stays in at least some sort of stand-by mode even when the host device is turned off by the user. The processor of the stove guard unit can be programmed to require, always when starting from a complete standstill, the user to push a button, or to give some other acknowledgement, before it allows for heating of any part of the stove.

The embodiment shown in <FIG> also comprises a user interface connected to the processor <NUM> and consisting of switches <NUM> and indicator lights <NUM>, as well as a memory <NUM> intended to be used by the processor, possibly for storing a program executable by the processor, and also for storing data, temporarily or permanently. Further, the stove guard unit comprises a data communication module connected to the processor <NUM> and enabling the processor <NUM> to communicate with a switch unit regulating the power supply to the stove unit and/or with a portable user terminal, such as a smart phone, for example, that can be used as a remote user interface to allow for easier and more versatile use of the stove guard unit, especially when the installation place of the stove guard unit in the host device makes it more difficult to use the switches <NUM> and/or the indicator lights <NUM>.

Claim 1:
A modular stove guard arrangement, comprising a stove guard unit (<NUM>, <NUM>, <NUM>) and, as its parts, at least
- an outer casing,
- inside the outer casing, a plurality of electronic components (<NUM>, <NUM>) at least partially coupled to each other to cause the stove guard unit to carry out stove guard operations, such as measuring the state of a stove (<NUM>) and/or the environment thereof, expressing the measured state as parameter values, comparing the parameter values and/the development thereof with decision conditions and giving an alarm and/or powering off the stove (<NUM>) in response to an exceptional circumstance found out in said comparison, and
- sensors (<NUM>) and a processor (<NUM>) coupled thereto,
in which stove guard arrangement
- said outer casing defines at least a mechanical connection (<NUM>) to a host device (<NUM>) to allow the stove guard unit to be at least mechanically included in an operating environment of the stove (<NUM>), such as a cooker fan or hood (<NUM>) located above the stove or immediate proximity thereof, and,
- said outer casing defines a power input connection (<NUM>, <NUM>) for receiving, through said host device (<NUM>), operating power for the stove guard unit(<NUM>, <NUM>, <NUM>), and/or said stove guard unit (<NUM>, <NUM>, <NUM>) has a location (<NUM>) for an internal operating-power source, such as one or more accumulators or batteries,
characterized in that
- said processor is adapted to identify the type of the stove (<NUM>) situated in proximity to the stove guard unit as one of: induction stove, ceramic stove, cast iron plate stove, based on the measuring data provided by said sensors (<NUM>), and
- said sensors comprise at least one of: electronic field sensor, microphone, radiation receiver operating in different wavelength ranges; and said measuring data is respectively indicative of the stove emitting one of: electromagnetic fields, buzz noise, visible light in the red end of the spectrum.