TECHNICAL FIELD

The invention relates to a stove safety system according to the preamble of claim 1.

PRIOR ART

A considerable portion of fires in dwellings real estates are due to stove fires. Stove fires often are caused by forgetting to turn off the stove or by grease uncontrollably catching fire while preparing food. Stove fires may be prevented through separate systems installed afterwards that improve the safety of using the stove, such as power or gas cut-off systems based on a timer and/or sensors such as tem- perature, infrared and/or gas sensors, which cut the stove's heat production after a pre-set time or when temperature in the stove area rises too much. These systems typically are placed in connection with the stove hood above the stove, for example, in the space intermediate the stove and the stove hood, using wall brackets, and/or at the power or gas supply. Locating the sensors such as based on sensor data to reliably interpret situations abnormal to the stove's regular behaviour, such as the stove inadvertently having been left operating, can be difficult because of the diversity of kitchens, and of kitchen units and devices. In particular, in situations where installing is the consumer's responsibility, the possibility of improper installation becomes apparent. Recent and most expensive stoves usually have safety features based on a timer also making possible the prevention of stove fires due to forgetfulness.

Damages from stove fires also can be prevented through systems based on preliminary fire extinguishing such as a sprinkler system or, particularly in the vicin- ity of the stove, directed extinguishing systems mounted above the stove hood, for example. These systems either are connected to a water distribution system or else have a separate tank of extinguishing agent installed inside the stove hood or the kitchen units. Such a system has one or more orifices through which the extinguishing agent is carried to the stove area. Retrofitting this system is difficult and requires a skilled technician. In particular, directing the orifice or orifices with sufficient accuracy towards the stove surface to optimize extinguishing efficiency is difficult because of varying installation environments. An extinguishing system retrofitted to a stove hood may also impede with using the stove hood, for example, with the removing and cleaning of grease filters, thus degrading fire safety.

Current stove safety solutions mainly are separate and independent device assemblies, or systems forming stationary parts of the stove hood.

Publication WO 2003/074940 discloses a power cut-off system having a number of different sensors, the data of which form a basis for decisions on hazardous situations in the stove area. The system comprises a visible part having sensors, a user interface and a microprocessor, and a hidden part coupled to the power supply of the stove. The devices of the visible part are located in a housing, which is mounted to the wall in the space between the stove and the stove hood.

Publication WO 2006/097575 discloses a system for monitoring and controlling the state of domestic appliances or computers or one or more entertainment devices. The system comprises an auxiliary device separately installed in connection with or integrated into the device being monitored, and which also can be connected to the energy supply of the device. In a stove application, the first auxiliary device is installed in connection with the stove and the second auxiliary device is installed in connection with the stove hood. The first and second auxiliary devices are communicating with each other over a wireless connection. The first auxiliary device examines through sensors the state of the stove and the presence of a user, and from the second auxiliary device is received information as to whether the stove is turned on, i.e., is the stove taking or not taking power from the electrical network. Based on the state information (stove turned on or stove turned off) re- ceived from the second auxiliary device, the first auxiliary device automatically turns on and off the vent motor of the stove hood and the light of the stove hood. Based on such state information received from the measuring sensors that is abnormal compared to normal use of the stove, the first auxiliary device controls the second auxiliary device to turn off the supply of energy to the stove.

Publication WO 2007/082993 discloses a stove safety system being composed of two units for retrofitting. The first unit is installed in a space inside the stove hood and the second unit is installed in the lower surface of the stove hood. These units wirelessly communicate with each other or do so over wires. The stove safety system has at least two heat sensors, one of which directly measures radiant temperature emitted by the stove and the second measures the stove's environmental temperature. Based on sensor data, the device raises an alert on the hazardous situation to a device installed at the power supply, said device then turning off the power to stove. The first unit may also be installed externally to the stove hood, wherein the second temperature sensor is installed inside the stove hood and the second externally to it, in the lower surface of the stove hood.

U.S. patent 4,830,116 discloses a targeted extinguishing system having several extinguishing nozzles and heat sensors locatable within the stove hood. The extinguishing nozzles are coupled via hoses to extinguishing agent units located spaced apart from the stove and the stove hood. The extinguishing system further has a switch, by which the power supply to the stove can be cut off.

U.S. patent 4,813,487 discloses a targeted extinguishing system that can be integrated into the stove hood afterwards such as not to be visible out of a normal viewing cone. The system has sensors, an extinguishing agent unit and extinguishing nozzles that accurately can be directed towards the centre of the stove. The extinguishing agent unit is coupled via a valve by pipelines to the extinguishing nozzles. The system further has a trigger mechanism based on heat-sensitive fuses. When the heat-sensitive fuses burn off, the trigger mechanism opens a valve connected to the extinguishing agent unit, wherein extinguishing medium flows through the piping to the extinguishing nozzles. For installation, the system requires a specific stove hood.

Publication WO 96/10444 discloses a targeted extinguishing system having power cut-off and extinguishing properties and being able to be integrated into a stove hood. The system requires a certain stove hood, wherein the safety system is isolated from other functions of the stove hood.

U.S. patent 4,050,291 discloses a safety device monitoring clogging of the grease filter in a stove hood. There is arranged a first bypass flow bypassing a grease filter and arranged a second bypass flow bypassing an activated carbon filter. Within each bypass flow there is arranged a thermistor heated by an electric current. The resistance of the resistor of the thermistor varies while the bypass flow cools it. When the grease filter becomes clogged, the bypass flow of the grease filter increases, which is seen as a change in the resistance of the thermistor of the grease filter. The change is measured by a resistor bridge to which the resistors of the thermistors are connected.

U.S. patent 3,690,245 discloses a thermostat-based stove safety system, wherein a safety device is integrated in connection with a grease filter into an entry aperture of the stove hood. The system automatically starts the stove hood when the temperature at the lower surface of the stove hood exceeds a first temperature threshold value indicating the onset of food preparation and automatically turns off the stove hood when the temperature in the stove hood rises too high indicating stove fire. A first temperature sensor monitoring the first, lower temperature threshold value is located in connection with a light device in the front part of the stove hood and a second temperature sensor monitoring a second, higher temperature threshold value is located in a fan chamber. The system further may have warning lights and an on/off -switch for these. U.S. patent 3,425,334 discloses a stove safety system, wherein a safety device is integrated into a removable grease filter located in an entry aperture of the stove hood. The system comprises a louver structure mounted onto an inner surface of the grease filter, which in the event of fire prevents flames from entering the fan conduit when the temperature exceeds a specific threshold value. When the louvers are open, air passes through the grease filter into the fan conduit and when the louvers are being closed, the passing of air through the grease filter into the fan conduit is prevented.

Current solutions carry several problems, particularly regarding ability for installation and operational reliability. Independent device assemblies are difficult to install in different kitchen environments such as to reliably function, as locating the sensors above the stove will vary depending on the technician. In addition, parts of the systems or system will remain visible and may hamper normal use of the kitchen. However, the safety devices for integration into the stove hood require either major alterations to the stove hood or else a stove hood particularly designed for this system, which is why the model range of stove hoods equipped with safety technology is extremely narrow, nor can a customer's all demands on building technique and desires on appearance be met. One problem with current extinguishing solutions also is that installing an orifice or orifices as required into various stove hoods such as providing sufficient extinguishing efficiency is difficult and often requires a stove hood of a special model or major alterations to the stove hood.

SUMMARY OF THE INVENTION

The object of the invention is a stove safety system that preferably and easily can be integrated into a number of different stove hood models either during manufacture of the stove hood or else through retrofitting. The main characteristics of the solution according to the invention are disclosed in the characterizing part of claim 1. Further characteristics of the invention are disclosed in the dependent claims.

The safety device connected with the stove safety system according to the invention can be integrated into various stove hoods without major alterations to the structure of the stove hood. The safety device is integrated in connection with a grease filter into an entry aperture of the stove hood such that the grease filter is replaced with a filter of differing model or size. The grease filter can be replaced with a grease filter narrowed on one side, whereby the safety device can be mounted to that edge of the entry aperture of the stove hood where the narrowed grease filter leaves an empty space. The grease filter also can be replaced with a shaped grease filter wherein a space receiving the safety device has been formed.

The solution according to the invention makes it possible that the safety device can easily and in a cheap way be integrated into a number of existing stove hoods produced by various manufacturers, either during manufacture or else through retrofitting, wherein customers can be offered a versatile and favourable range of stove safety.

The stove safety system according to the invention reliably operates in various kitchen environments, and a wide range of models covers all building technique needs and customer demands.

Generally, grease filters in the stove hood models of one manufacturer and also in those of different manufacturers are close to being similar, wherein the safety device can be adapted to most stove hood models.

In the present application, stove hood denotes all such structures installed above a stove that carry the purpose of removing cooking or frying fumes. In its simplest appearance a stove hood is a mere dome or hood wherefrom an exhaust conduit leads to the roof of the building. Then, on the roof there may be present an exhaust air fan sucking air from the exhaust conduit and stove hood. However, the stove hood as such may have a fan sucking air from the hood and blowing it through the exhaust conduit out from the building, or via an activated carbon filter back to the stove space.

In the present application, removable grease filter primarily denotes a grease filter that can be removed from the stove hood and mounted to the stove hood without using tools. Also, a grease filter the removal of which only requires detaching a few screws, for example, is within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In Fig. 1 is shown one stove hood equipped with two removable grease filters.

In Fig. 2 is shown a stove hood according to Fig. 1 that is equipped with two removable grease filters, wherein is integrated a safety device connected with the stove safety system according to the invention.

In Fig. 3 is shown a stove hood according to Fig. 1 that is equipped with one removable grease filter, wherein is integrated a safety device connected with the stove safety system according to the invention.

In Fig. 4 is shown an enlargement of a safety device applicable to stove safety system according to the invention, and its block diagram.

In Fig. 5 is shown one application according to the invention, wherein an extinguishing agent unit is connected to the safety device.

DESCRIPTION OF PREFERABLE EMBODIMENTS In Fig. 1 is shown one stove hood 10 equipped with two removable grease filters 14a, 14b. The stove hood 10 comprises a tapered frame part 11 and flue-formed frame part 12. The tapered frame parts 11 has an entry aperture 13, wherein is adapted two grease filters 14a, 14b. The grease filters 14a, 14b are removably at- tached to the edges of the entry aperture 13 of the tapered frame part 11. The stove hood 10 is located above the stove (not shown in the figures), wherein fumes created while cooking or frying on the stove will pass through the grease filters 14a, 14b inside the tapered frame part 11 and flue-formed frame part 12 of the stove hood 10 to the exhaust flue 50 (see Fig. 5) and via the exhaust flue 50 to the outside of the building. As regards the invention, the stove hood 10 can be a model equipped with any known stove hood technology, such as, for example, a stove hood, dome or hood equipped with a separate motor, a valve, or control of a roof-installed extractor.

In Fig. 2 is shown a stove hood according to Fig. 1 that is equipped with two removable grease filters, wherein is integrated a safety device connected with the stove safety system according to the invention. Here the safety device 20 is integrated into the entry aperture 13 of the stove hood 10 such that the original grease filters 14a, 14b of the stove hood 10 on one side has been replaced with narrower models 15a, 15b. These narrower grease filters 15a, 15b leave a free space 13a at the front edge of the entry aperture 13 of the stove hood, wherein using adapter plate 30 the safety device 20 can be installed. The safety device 20 is attached to the adapter plate 30 and the adapter plate 30 is mounted to the front edge 13a of the entry aperture 13 of the stove hood 10. The grease filters 15a, 15b subse- quently are installed at the entry aperture 13 of the stove hood 10. The adapter plate 30 is fastened with a quick-disconnect fitting to the edges of the entry aperture 13 of the stove hood 10 and the grease filters are fastened with a quick- disconnect fitting to the edges of the entry aperture 13, and the edge of the adapter plate 30. Thus integrating the safety device 20 into the stove hood 10 does not re- quire other alterations to the stove hood 10 replacing the original grease filters 14a, 14b on their one side with narrower grease filters 15a, 15b. Thus the safety device 20 favourably can be integrated into most already existing stove hood models without major alterations to the structure of the stove hood 10. Using adapter plate 30 the safety device 20 can be adapted to the entry aperture 13 of almost all stove hood models 10 equipped with removable grease filter 14a, 14b.

In Fig. 3 is shown a stove hood according to Fig. 1 that is equipped with one removable grease filter, wherein is integrated a safety device connected with the stove safety system according to the invention. In this application the original removable grease filter has been replaced with a shaped grease filter 16. This new grease filter 16 is formed such that a free space 13b is left at the front edge of the entry aperture 13 of the stove hood 10, into which the safety device 20 can be integrated. Thus, in this solution no adapter part 30 is necessary for integrating the safety device 20 into the entry aperture 13 of the stove hood.

In Fig. 4 is shown an enlargement of a safety device 20 adaptable to the stove safety system according to the invention, and its block diagram. The safety device 20 preferably comprises at least one sensor 21 and a control unit 25, and a user interface 23 for controlling the safety device 20. The user interface 23 preferably has a warning device 23a and push buttons 23b. The safety device 20 further pref- erably has a wireless or wired data communications unit 24 enabling the communication of data on the state of the stove to external units of the safety device 20 and data from the external units of the safety device 20 to the safety device. The safety device 20 also is connected with a power source 26. The safety device 20 typically has sensors 21 sensing the presence of carbon monoxide and/or gas and/or IR and/or temperature and/or a person. From the sensor data a control unit 25 in the safety device 20 deducts hazardous situations occurring in using the stove or oven. In situations where the safety device 20 is connected to an extinguishing agent unit, the safety device 20 also has at least one extinguishing nozzle 22. The safety device 20 also can be connected to a cut-off unit 100 coupled to the energy supply of the stove. This connection can be a one- or two-way connection. In Fig. 5 is shown one application according to the invention, wherein an extinguishing agent unit is connected to the safety device. The extinguishing agent unit 40 can be installed inside the stove hood 10 or outside the stove hood 10, for example, inside kitchen units (not shown in the figures) or some other suitable place in the stove space. The extinguishing agent unit 40 is connected via a hose 41 or other similar union to at least one extinguishing nozzle 22 located in the safety device 20. Triggering of the extinguishing agent unit 40 can be done either intelligently through interpreting sensor data 21 at the safety device 20, or using a fuse reacting on temperature, such as a glass capsule known in sprinkler systems.

When the stove safety system detects an abnormal temperature rise and/or formation of flue gases from a fire load, the control unit 25 directs the warning device 23a to warn of the fire, for example, using an audio signal and/or a warning light. In case the user does not acknowledge the warning at user interface 23 within a preset time period, the stove safety system directs the cut-off unit 100 to cut off power to the stove's power supply. Then the stove is safety system continues monitoring sensor data 2, and if the information received on the state of the environment still develops unfavourably, such as flue gas increasing and/or temperature rising, the control unit 25 directs the warning device 23a to warn the user of fire hazard through an audio signal and/or a warning light. In case the user does not acknowledge the warning from the warning device 23a within a preset time period, the stove safety system triggers the extinguishing agent unit 40, wherein the extinguishing agent flows from the extinguishing nozzle 22 and extinguishes the fire.

Integrating the safety device 20 connected with the stove safety system according to the invention into the entry aperture 13 of the stove hood 10 can be carried out either such that the safety device 20 as such is applicable for attachment to a number of different stove hoods 10, or else during integration using an adapter part 30 by which the safety device 20 is attachable to a number of different stove hoods. The safety device 20 preferably is integrated into the entry aperture 13 of the stove hood 10 such that it is not fixedly attached to the grease filter 16 or grease filters 15a, 15b. When the grease filter 16 or grease filters 15a, 15b are separate removable parts; they easily can be washed, for example, in a dishwasher.

The fitting structures of the grease filter 16 or grease filters 15a, 15b and safety device 20 preferably is based on quick-disconnect coupling techniques known to persons skilled in the art. The grease filter 16 or grease filters 15a, 15b are at- tached to the edges of the entry aperture 13 of the stove hood 10 preferably using quick-disconnect coupling techniques and not using tools and the safety device 20 similarly is attached to the edges of the entry aperture 13 and/or the edges of the grease filter 16 or grease filters 15a, 15 preferably using quick-disconnect coupling techniques and not using tools.

The embodiment shown in Fig. 3 has one grease filter 16 and the embodiment shown in Fig. 2 has two grease filters 15a, 15b, but of course, as regards the invention there could be any number of grease filters.

In the embodiment shown in Fig. 3 a front edge of the grease filter 16 preferably is formed with a free space 13b, into which the safety device 20 can be installed. Of course, this free space 13b can be formed in the edge of any grease filter 16 or even in the centre of the grease filter 16.

To attach the grease filters 15a, 15b and/or the safety device 20 one can use, for example, spring loads, clips, pop rivets or screws known to persons skilled in the art.

Described above are only a few preferable embodiments of the invention, it being apparent to persons skilled in the art that numerous modifications can be performed on these and yet remain within the scope of the appended claims.