SAFETY DEVICE FOR A STOVE, IN PARTICULAR A PARAFFIN STOVE

Abstract: A safety device for a stove of the type wherein during normal operation the height of flames produced by the stove being beyond a certain range and/or of the extent to which a heating means becomes hot is characteristic for an undesired operating condition, whereby said device comprises a sensor means for scanning said height(s) and on their being beyond the respective range producing a detection signal representative therefor and an actuator means for setting the stove in a desired operating condition or putting the stove out of action in response to said detection signal.

Description: Safety device for a stove, in particular a paraffin stove. The invention relates to a safety device for a stove wherein during normal operation the height of flames produced by the stove being beyond a certain range and/or of the extent to which a heating means becomes hot is characteristic for an undesired operating condition. The present invention relates in particular to a paraffin stove. Besides the conventional types of paraffin stoves several more modern types are now on the market, among which one type with an initial, incomplete combustion at e.g. 800° C and a second combust¬ ion at e.g. 1200° C, whereby gaseous effluents are combusted. With the latter type no measurable production of carbon monoxide takes place. For the environment and the safety of the user this type is to be preferred therefore. Said advantages of this type of paraffin stove however, are only achieved with a correct adjustment of the burner, among which the adjusted height of the wick and the presence of oxygen. In most cases the adjustment of the wick is done by hand. The result of a wick adjusted too low or too high is in both cases an abnormal com¬ bustion of the stove, resulting in the occurrence of soot and/or smell. In the first case the burner for the initial combustion does not become hot over the entire range and in the second case the flames developed in the burner for the second combustion are too large. The above-mentioned disadvantages therefore occur with an incorrect adjustment of the height of the wick. Also with a correctly adjusted wick it is possible that ■ there occurs abnormal combustion, i.e. a combustion with a flame smalle than minimum in the burner for the second combustion, also called upper burner. This may be the case when the wick is correctly adjusted, but there is too little oxygen present. With this abnormal combustion carbon monoxide might be produce. This, too, may constitute a dis ¬ advantage. The purpose of the invention is to remove one or more of the above-mentioned disadvantages and/or other disadvantages of known stoves and for that purpose provides a safety device of the kind mentioned in the preamble, which is characterized in that it comprises a sensor means" for scanning said height(s) and, when they are beyond the respective range, giving a detection signal representative therefor and an actuator means for setting the stove in a desired operating- condition or putting the stove out of action in response to the detectio signal. The safety device according to the invention advantageously comprises therefore a sensor means with one or more sensors for detecting one or more of the following conditions with a paraffin stove with two-stage combustion: too low flames, too high flames, the burner for the initial combustion being hot within a too small range. It should be remarked hereby that the sensor for the last-mentioned condition will be located comparatively high relative to the lower burner. With a type of paraffin stove with a single burner corresponding with the afore-mentioned lower burner the sensor will be placed comparatively low relative to said burner. According to the invention therefore the undesired operating condition, i.e. the stove operating when insufficient oxygen is present and the stove operating- such that soot and/or smell is produced will be detected. Furthermore the safety device according to the present invention advantageously comprises an actuator means which, when the stove operates when too little oxygen is present, puts said stove out of operation by e.g. putting the burner out of action or, with an operation condition of the stove whereby soot and/or smell is produced, sets the stove in a desired operating condition by e.g. automatically adjusting the wick to a suitable height, among which the maximum height, the minimum height or a height between said heights. Besides it is -possible that means are provided to put the stove out of operation yet when the safety device has already set the stove one or more times from an undesired operating condition into a desired condition. The invention will be described in detail hereinafter with reference to a-possible embodiment, illustrated in the single figure of the drawing, applied on the two-stage combustion type of paraffin stove. Although the drawing illustrates the invention as applied on a paraffin stove of the two-stage combustion type, it will be apparent that the invention can.also be advantageously applied on a paraffin stove of the single-stage combustion type. Besides the inventio does not relate to paraffin stoves only, but as far as can be seen now it does yield the most advantages with that application. In general the safety device, which will have an electric or electronic nature can be applied on stoves of the type wherein during normal operation the height of the flamesor a single flame produces by the stove being beyond a certain range, i.e. being lower and/or higher and/or the hight of the extent to which a heating means, i.e. burner, becomes hot is character¬ istic for an undesired operating condition of the stove, i.e. too little oxygen is present with the risk of producing carbon monoxide or the abnormal burning of the stove, whereby soot and/or smell is produced. In the figure of the drawing reference number 1 indicates a strongly diagrammatically and simplified representation of a paraffin stove of the two-stage combustion type, whilst reference number 2 indicates the safety device according to the present invention, be it in the form of a much simplified block diagram. In this connection it is remarked that for a person skilled in this field of the art it will undoubtedly be apparent by means of said strongly simplified block diagram how to arrange the safety device, in particular the electric or electronic part thereof using components according to the present state of the art, among which a range of sensors, actuators, digital circuits and even microprocessors. In the very first place a brief description will be given of the paraffin stove 1. The paraffin stove 1 comprises a tank 11 for paraffin or another suitable liquid fuel. Connected with the tank 11 is a burner regulator 12 with a fuse means 13, in particular a wick. The burner regulator is provided with an adjusting means not further illustrated, for adjusting the height of the fuse means which is naturally connected with the paraffin present in the tank 11. By lighting the paraffin-soaked fuse means a combustion will take place as a t • -- result of the evaporation of the paraffin and its reaction with oxygen, which produces heat. Said lighting may be done e.g. with matches, but in the illustrated embodiment of the paraffin stove 1 an ignition means 14 is provided, being electronic in said illustrated embodiment. Furthermore connected with the burner regulating means is a safety mechanism 15 operating in this embodiment with the adjusting means mentioned before and not illustrated to make the fuse means go down so far that the fire is put out when the paraffin stove 1 is overturned or knocked down. This is one of the ways of what is called putting the burner out of action. Connected with the burner regulator is a heating means or burner head, comprising a lower burner 16 and an upper' burner 17. In the case illustrated the lower burner 16 comprises an element in the form of substantially a closed tube. On the upper side of the non- perforated tube of the upper burner 17 a plate 19 has-been placed. The flame or flames 18 hereby develop mainly along the circumference of the non-perforated tube, deviating, as a result of the action of the circula plate 19, upwards from said surface of the cilindrical non-perforated tube, so taht an upwardly fanned out shape arises. The safety mechanism may comprise a counterweight and a pawl, whereby the pawl is biased with the counterweight on adjustment of the wick height by the burner regulator, which may be called the putting into action of the burner, whereby on excitation by e.g. pushing against the safety mechanism 15 the counterweight is displaced, the pawl moves back and the wick height is adjusted to its minimum by the adjusting element and the burner, as said before, is put out of action. It is remarked that paraffin stoves with an electric ignition are known, for which purpose there is a provision in the paraffin stove for the connection and accommodation of one or more batteries. In principle it is possible, therefore, that there is a source of electric energy present in the known paraffin stoves. Furthermore it is remarked that paraffin stoves are known or conceivable with in addition to a source of electric energy an electronic device for controlling the putting into and out of action of the burner as well as the adjustment of the height of the fuse means, e.g. in " operation with a possibly electronic time clock and a thermostat. The larger part of the time^ clock may comprise a part of afore-said integrated circuit ( iming part) . The same may apply to the thermostat. It is remartked at the outset, therefore, that the safety device can simply be built into known paraffin stoves by providing therin a sensor means and an actuator means and providing electronic circuitry or modifying the electronic device present, which may in practice boil down to replacing one chip by another. Hereinafter the safety device or the present invention will be more specifically discussed. The safety device 2, being electronic by nature in the illus¬ trated embodiment, comprises an electronic circuit 24, a sensor means 21a,21b, 22a, 22b, an actuator means 29 and a power supply means which last means may be formed by the batteries already present in the stove. Besides the illustrated safety device according to the invention comprises a delay means 27 and a response delaying means 28, whose operation will be explained in detail later on, as well as a time clock means 25 and a thermostat means 26, which may have been formed by the afore-mentioned time clock and thermostat or may comprise these. Although the illustrated safety device is electronic by natur as said before, this is not necessary; when e.g. the sensor means comprises a bimetal said bimetal may control the actuator means 29 directly. The safety device 2 therefore comprises a sensor means 21a-b, 22 a-b, which comprises at least one sensor. The sensor means scans or detects whether the height of the flame or flames is beyond a certai range, i.e. whether the flame is too low and/or too high. In the illustrated embodiment the sensor means comprises in particular a first flame sensor 21a and a second flame sensor 21b, whereby the first flame sensor 21a is located at a comparatively great height and the flame sensor 21b is located at a comparatively small height relativ to the upper burner 17. The first flame sensor 21a therefore detects too high flames and the second scanning sensor -detects too low flames. Put in other words the first flame sensor 21a detects an abnormal operating condition whereby soot and/or smell is produced, whilst flame sensor 21b detects an abnormal operating condition whereby too little oxygen is present and there is a danger of carbon monoxide being produced. In particular when a time clock means 25 is provided the sensor 21a is important, because possibly the production of soot and/or smell is not detected by a person. At all times it applies that the flame sensor 21b is of great importance, because it makes it possib as it were to detect that there is too little oxygen for a safe operation of the paraffing stove. The flame sensor may e.g. be a thermo couple, bimetal, a visible light sensor, an invisible light sensor or an ionisation sensor. It will be apparent to the average person skilled in this field of the art how a useful detection signal can be obtained from said sensors. The same applies with relation to their location relative to the upper burner. Next to, as in the illustrated embodiment, or instead of the flame sensor 21a and/or 21b the two-stage paraffin stove may comprise a heat or radiation sensor 22a, which is located at a comparatively great height relative to the initial burner 16. Said heat or radiation sensor 22a has a function similar to that of flame sensor 21a, be it that the operating condition related to the sensor 22a occurs with a fuse means 13 adjusted too low. Although the embodiment illustrates a second heat or radiation sensor 22b, it is specifically intended for a paraffin stove with a single burner head 16. In that case the sensor 22b is located at a comparatively small height relative to the burner 16 in order to have an operation analogue to that of sensor 21b, viz. too little oxygen for an adequate combustion with the corresponding possible danger of carbon monoxide being developed. In the case of a single-stage paraffin stove two heat or radiation sensors 22a, 22b may be provided, whereby sensor 22a corresponds with a too high position of the wick and sensor 22b may be (also) representative for a fuse means 13 adjusted too low. The heat or radiation sensors 22a, 22b may e.g. be a thermo couple, a bimetal or an infrared sensor. The signals of the sensors 21a-b, 22a-b are supplied to the electronic circuit. Preferably the electronic circuit 24 has a discriminating element to dertermine whether the detection signal of the sensors is representative for the case of too little oxygen being present or for the case of soot and/or smell being produced. In the first case the electronic circuit 24 will excite the actuator means 29 to put the burner 16,17 out of action; whereas in the second case the electronic circuit may drive the actuator means to make the adjusting means of the burner regulator 12 adjust the fuse to a certain position, as said before possibly a minimum, intermediate or maximum position. Besid the electronic circuit may comprise a counting means to record how often the adjusting means has been driven by the actuator menas to assume a correct position from a position too high or too low and a detecting means to put the burner out of action yet after a certain numer of times having been counted by the counting means. The detection signals may hereby simulate the operation of the time clock means 25 and/or the thermostat means 26, therefore. For putting the burner out of action as well as for adjusting the fuse means the actuator means 29 may be connected with the adjusting means of the burner regulator. Also it is possible for the actuator means to be connected to the safety mechanism in order to simulate an overturn or knock¬ down, as it were. In view of that which is discussed directly above the actuato means may comprise an electromotor for separately controlling the adjusting height of the fuse means 13, i.e. independent of the burne regulator, with which the fuse height can be adjusted by hand, whereby preferably the safety mechanism 15 is at once set "ready" for action. The actuator means may also be of the electromagnetic type for, if driven, pushing over the switch pawl of the safety mechanism 15, thus simulating an overturn or a knock-down. In the concrete the driving means may be an electromagnet. Now the reason for providing the delay means 27 and the response delaying means 28 will be further discussed. The delay means 27 has for its function the blocking, for a certain time, of the drivability of the actuator means 29. A certain time elapses namely between the moment when the stove is (can be) put into action and the moment when flames develop as illustra in the embodiment, i.e. normal operation. In order to prevent a false indication of too low flames now the detecting needs to be delayed for as long as is necessary for the stove " to reach " its normal operation after having been started. Consequently the delay time of the delay means 27 is adjusted. Said delay means 27 may be a timer and be incorporated in an integrated circuit or be provided in the form of a separate (smaller) integrated circuit. The response delaying means 28 is also provided to prevent false triggering of the actuator means on the basis of detection signals of the sensor means in e.g. the case of flaring of the flame, whereby the flame may be too low for a short period of time. This response delaying means may be realized in a timer-IC or be incorporated in a larger integrated circuit. It will be apparent that the delay time of the delay means 27 will be longer ' than that of the response delaying means 28.

Claims: CLAIMS 1. A safety device for a stove of the type wherein during normal operation the height of flames produced by the stove being beyond a certain range and/or of the extent to which a heating means becomes hot is characteristic for an undesired operating condition, characterised in that it comprises a sensor means for scanning said height(s) and on their being beyond the respective range producing a detection signal representative therefor and an .actuator 4 means for setting the stove in a desired operating condition or putting the stove out of action in response to said detection signal. 2. A safety device as claimed in claim 1, characterised in that between the sensor means and the actuator means an electric or electronic circuit is connected for sending a drive signal to the actuator means in response to the detection signal of the sensor means. 3. A safety device as claimed in claims 1 or 2 for a paraffin stove with a burner head, comprising the heating means in the form of substantially a perforated tube, characterised in that the sensor means comprises at least one heat or radiation sensor located at a certain height relative to the tube. 4. A safety device as claimed in any of the preceding claims for a paraffin stove with a burner head, comprising an upper burner, in particular with substantially a non-perforated tube, along the outside surface of which flames develop during operation, characterised in that the sensor means comprises at least one flame sensor located at a certain height relative to the tube. 5. A safety device as claimed in claim 3, characterised in that the sensor means comprises two heat or radiation sensors, one of which is located at a comparatively great height and the other at a comparatively small height. 6.A safety device as claimed in claims 3 and 4, characterised in that the sensor means comprises one heat or radiation sensor located at a comparatively great height. 7. A safety device as claimed in claims 4 or 6, characterise in that the sensor means . comprises two flame sensors, one of which is located at a comparatively great height and the other at a com- paratively small height. 8. A safety device as claimed in any of the claims 3, 5 or 6, characterised in that the heat or radiation sensor is either a thermo couple, or a bimetal or an infrared sensor. 9. A device as claimed in any of the claims 4, 6 or 7, charact erised in that the or a flame sensor is either a thermo couple, or a bim or a(n) (in)visible light sensor or an ionisation sensor. 10. A safety device for a paraffin stove with a burner regu¬ lating means comprising a holder for a fuse, means and an adjustin means for adjusting the height of the fuse means characterised in that the actuator means is connected to the adjusting means. 11. A safety device as claimed in claim 10, characterised in that the actuator element comprises an electromotor. 12. A safety device as claimed in any of the preceding claims for a paraffin stove with a safety mechanism that puts the stove automatically out of operation when e.g. it is knocked-down by e.g. putting the burner of the stove out of action, characterised in that the actuator means, when driven, triggers the safety mechanism. 13. A safety device as claimed in claims 10 or 11 and 12, characterised in that the safety mechanism forms part of the adjusting means. 14. A safety device as claimed in claim 12 or 13, wherein the safety mechanism is provided with a switch pawl, characterised in that the actuator means is of an electromagnetic type and is provided in a cooperative relation to the switch pawl. 15. A safety device as claimed in any of the preceding claims, characterised in that it comprises a detection means for detecting the lighting or coming into operation of the stove, as well as a delay means initiated by the detecting means for blocking , the drivability of the actuator means for a certain period of time. 16. A safety device as claimed in any of the preceding claims, characterised in that it comprises a response delaying means for blocking the drivability of the actuator means for a certain period of time after reception of the detection signal and for only releasing the drivability of the actuator means when the detection signal is maintained after the certain period of time has elapsed. 17. A safety device for a paraffin stove with a time clock mea and/or a thermostat means and an electronic device in the form of e.g. an integrated circuit for putting the burner into and out of action in response to signals of the time clock means and/or thermostat means, or regulating the heat to be delivered by the burner, respectively, characterised in that the electronic device comprises the electronic circuit and/or the delay means and/or the response delaying means and simulates, on the basis of the possibly delayed detection signal, the switching off of the time clock means and/or the regulating to a certain value of the thermostat means.

Inventors: MINTEN HUBERTUS LEONARDUS, MINTEN JOHANNES MARTINUS, MINTEN, HUBERTUS, LEONARDUS, MINTEN, JOHANNES, MARTINUS
Applicants: MINTEN HUBERTUS LEONARDUS, MINTEN JOHANNES MARTINUS, MINTEN, HUBERTUS, LEONARDUS, MINTEN, JOHANNES, MARTINUS
Application year: 1986
Main classification: F23N5
IPC codes: F23N5, F24C5