EP2949998A1 - Gas burner device with flame monitoring electrode - Google Patents

Abstract

A gas burner device (10) comprises a burner body (20), an ignition electrode (30), a flame monitoring electrode (40), a common electrode terminal (60) and a control device (70). The ignition electrode (30) is connected to the electrode terminal (60) via a spark gap (35), and the flame monitoring electrode (40) is directly connected to the electrode terminal (60). The ignition electrode (30) has a smaller breakdown voltage toward the torch body (20) than the flame monitoring electrode (40). This makes it possible to implement ignition and flame monitoring functions using only one electrode terminal (60). The gas burner device (10) can be used with the control device (70) in a gas burner arrangement (5).

Description

The invention relates to a gas burner device and a gas burner arrangement with such a gas burner device.

A gas burner device is for example from DE 10107190 C1 known. Such gas burner devices can be used for example as a heat source for cooking or frying devices such as cookers or ovens.

Typical grass burner devices have a burner body with a number of mutually adjacent gas outlet openings, from which flammable gas flows during operation of the gas burner device. While in the past the gas was mostly ignited manually, current gas burner devices typically have an ignition electrode to which a voltage for forming an arc can be applied. By means of this arc, the escaping gas can be ignited.

In the automatic ignition of gas burner devices, however, eliminates the previously customary manual control of whether a flame actually spreads correctly across all gas outlet openings. Especially in installation situations with difficult visibility conditions, for example in ovens, this can be problematic. For example, if objects such as parts of a food or cooking utensils fall on the burner body, so that some of the gas outlet openings can be covered. This can prevent a flame ignited at the ignition electrode from spreading across all the gas outlet openings. This is problematic, in particular, because in this case gas escapes from the gas outlet openings to which the flame has not spread, which does not burn. This gas is in any case undesirable and annoying at best, but it can also lead to considerable risk of fire and explosion.

It is known in the art to monitor the correct propagation of the flame across the gas exit openings by means of a thermocouple which is opposite the ignition electrode with respect to the burner body. If the flame does not propagate properly, this thermocouple detects too low a temperature. In this case, for example, a controller interrupt the further gas supply. Due to the heat, which also from However, a flame emanating only partially expanded, such arrangements are not very reliable.

Furthermore, it is known in the art to measure the generation of a flame by measuring current flow from the ignition electrode across the flame to the burner body, in which case the burner body is typically formed of a conductive material and also grounded. Although this allows a more reliable detection of whether a flame has been ignited, but involves the problem that in this case, the measurement can be made only on the ignition electrode. It can not be recognized, therefore, whether a flame has actually spread over all gas outlet openings.

It would be conceivable to provide an additional flame monitoring electrode, which is arranged at a position remote from the ignition electrode and is connected to a separate monitoring circuit which monitors the correct propagation of the flame. However, such a design would have the disadvantage that an additional monitoring circuit would be required, which would mean, for example, in existing systems that must be intervened in existing electronics. This would involve considerable development effort and also the need to re-approve the device.

Task and solution

It is an object of the invention to provide a gas burner device in which with as little or no change existing control components reliable monitoring of the spread of the flame over all gas outlet openings is possible. It is a further object of the invention to provide a gas burner assembly with such a gas burner device.

This object is achieved by a gas burner device with the features of claim 1 and by a gas burner arrangement with the features of claim 12. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only for the gas burner device or only for the gas burner assembly. However, they should be able to apply independently of both for the gas burner device as well as for the gas burner assembly independently. The wording of the claims is incorporated herein by express reference.

The gas burner device according to the invention has a burner body with a number of adjacent gas outlet openings, an ignition electrode, a flame monitoring electrode, and a common electrical electrode connection for the electrodes to a control device of the gas burner device. The ignition electrode is connected to the electrode terminal via at least one spark gap, and the flame monitoring electrode is directly connected to the electrode terminal. The ignition electrode and the flame monitoring electrode are arranged adjacent to the burner body in such a way that the ignition electrode has a smaller breakdown voltage toward the burner body than the flame monitoring electrode or the breakdown voltage to the burner body is greater in the flame monitoring electrode.

By means of the gas burner device according to the invention, it is possible to provide both the functionality of the automatic ignition and the functionality of monitoring the correct propagation of the flame over all gas outlet openings using only one electrode connection. An additional connection with appropriate electronics can be dispensed with.

The operation of the gas burner arrangement according to the invention is briefly outlined below.

A spark gap is typically a component which only becomes conductive when an applied voltage is greater than a breakdown voltage of the spark gap. Such a sufficiently large voltage typically leads to the ionization of a gas located in a discharge space between two electrodes. This becomes conductive and the spark gap is shorted in this way within fractions of a microsecond. In the present case, the spark gap in particular fulfills the task of short-circuiting a voltage applied to the electrode connection to the ignition electrode only when ignition is intended. When an ignition is typically applied a correspondingly high voltage. If only a lower voltage than the breakdown voltage, so this voltage is typically the measurement and is separated by the spark gap of the ignition electrode. A current flowing due to the flames, which indicates a flame which has spread correctly, can thus flow only through the flame monitoring electrode. It is also possible to connect several spark gaps in series, advantageously two spark gaps. Their breakdown voltages then add up to a total breakdown voltage.

However, the provision of the spark gap alone would not be sufficient to ensure that the ignition takes place at the ignition electrode. This is achieved by the second measure provided according to the invention, namely that the ignition electrode has a lower breakdown voltage towards the burner body than the flame monitoring electrode. This ensures that when the ignition voltage is applied with the correct height or voltage, a spark jumps from the ignition electrode to the burner body, whereas no spark jumps from the flame monitoring electrode to the burner body. In other words, the embodiment according to the invention makes it possible to select an ignition voltage in which a spark jumps to the burner body only at the ignition electrode, but not at the flame monitoring electrode. Thus, the ignition voltage is preferably in the range between the breakdown voltage of the ignition electrode and the breakdown voltage of the flame monitoring electrode, in each case towards the burner body.

In order to achieve the lower breakdown voltage, according to one embodiment, the ignition electrode has a differently shaped electrode tip than the flame monitoring electrode, preferably a more pointed electrode tip. This is one way to lower the breakdown voltage. Alternatively, the ignition electrode to achieve the smaller breakdown voltage of the ignition electrode may be arranged at a smaller distance from the burner body than the flame monitoring electrode. This is based on the finding that the breakdown voltage increases with the distance of a respective electrode to the torch body. By increasing the distance, the breakdown voltage can thus also be increased. The distance defined here is the smallest distance between an electrode and the torch body, ie the distance at which the breakthrough takes place.

The ignition electrode preferably has a distance of 3 mm to 5 mm, more preferably about 4 mm, from the burner body. The flame monitoring electrode preferably has a distance of 5 mm to 7 mm, particularly preferably about 6 mm, from the burner body. These values have proven to be advantageous in practice in gas burners, as used in particular in gas ovens. In particular, it is preferred if the flame monitoring electrode has a distance which is about 30% to 70% greater than the distance of the ignition electrode from the burner body.

According to one embodiment, a spark gap is formed as a gas-filled discharge space between a first spark gap electrode and a second spark gap electrode, wherein the first spark gap electrode is connected to the ignition electrode and the second spark gap electrode is connected to the electrode terminal. Both have spark gap electrodes a defined distance from each other. Alternatively, the spark gap may also be formed as an electronic component. If several or advantageously two spark gaps are provided, they may indeed be designed differently, for example one with spark gap electrodes and one as an electronic component. Advantageously, however, they are then identical.

The ignition electrode and the flame monitoring electrode are preferably fixed to the burner body. This allows a compact and easy-to-handle design. In addition, the distances of the electrodes to the burner body can be defined very well, accurately and relatively easily.

The ignition electrode and the flame monitoring electrode preferably have positions which are far apart from one another or even more preferably even opposite one another on the burner body. Advantageously, their distance is at least 50% of the length of the burner body. Positions can be particularly advantageous at respectively remote end regions on the burner body, above all the ignition electrode is advantageously arranged at an end region. It can thus be achieved that the ignition electrode ignites the flame on one side of the burner body, and the flame monitoring electrode reliably detects a flame only when the flame has spread correctly over all the gas outlet openings to the other end.

The spark gap preferably has a breakdown voltage of 250 V to 450 V, particularly preferably 400 V. These values have proved to be advantageous in practice.

Preferably, the flame monitoring electrode is arranged so that its tip is within a flame when the flame burns on the gas burner device. This allows a reliable detection of a flame by means of a current flow through the flame monitoring electrode to the burner body.

The invention further relates to a gas burner arrangement which has a gas burner device according to the invention as described above and a control device with an output which is designed to connect the electrode connection of the gas burner device. The control device is designed to output at the output an ignition pulse with an ignition voltage which is higher than the breakdown voltage of the ignition electrode to the burner body and smaller than the breakdown voltage of the flame monitoring electrode to the burner body. The control device is designed to be at the output to output a measurement voltage for detecting a flame burning at the gas burner device, which is smaller than the breakdown voltage of the spark gap.

By means of the gas burner arrangement according to the invention, the advantages described above with reference to the gas burner device according to the invention can be utilized for a gas burner arrangement. With regard to the gas burner device can be used on all variants and designs described above. Illustrated benefits apply accordingly.

The controller may include, for example, a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), a programmable logic controller (SPSS), or other programmable unit for performing control tasks. In particular, the gas burner arrangement may comprise processor means and storage means, wherein program code is stored in the storage means which, when executed by the processor means, controls the behavior of the gas burner arrangement.

By emitting an ignition pulse, a flame can be ignited on the gas burner device. By means of the measuring voltage can be detected whether the flame has spread correctly over all gas outlet openings of the gas burner device. The control device can thus control both functions of the gas burner device in an advantageous manner and thus enables an autonomous operation of the gas burner device.

The ignition voltage is preferably between 8 kV and 12 kV, more preferably 10 kV. More preferably, the ignition voltage is smaller than the breakdown voltage of the flame monitoring electrode. The measuring voltage is preferably between 200 V and 260 V, particularly preferably 230 V, these values being RMS values and the measuring voltage being AC voltage, so that the maximum value is 325 V. These values have proven to be advantageous in practice.

According to a preferred embodiment, the control device is designed to output the ignition pulse with a defined time duration for ignition of the gas burner device and then to output the measurement voltage, and thus to monitor a flame burning at the gas burner device. This allows an advantageous embodiment of the control device for autonomous operation of the gas burner assembly, which can be dispensed with manual controls, without posing the risk that unburned gas escapes.

It is understood that the control device can take on even more functions, in particular the control of a supply of gas to the burner body. Thus, the ease of use of the gas burner assembly can be further increased and the operation can be further automated. In particular, the control device may be configured to interrupt the supply of gas to the burner body, if the flame monitoring electrode does not detect a flame within a defined period after the end of the ignition pulse. This indicates that the flame has not spread correctly over all gas outlet openings and thus gas escapes unburned. As an alternative or in addition to this, the control device may, for example, also output a warning message to a user, for example in an optical or acoustic manner.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into intermediate headings and individual sections does not limit the general validity of the statements made thereunder.

Brief description of the drawing

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are described below with reference to the Fig. 1 are explained. It shows Fig. 1 a gas burner assembly with a gas burner device according to the invention.

Detailed description of the embodiment

Fig. 1 shows a gas burner assembly 5 according to the invention with a gas burner device 10 according to the invention. The gas burner device 10 has a burner body 20. The burner body 20 has a gas inlet 22 and a plurality of mutually adjacent gas outlet openings 25. Into the gas inlet 22 combustible gas with a certain amount and pressure can flow, controlled in a known manner by a gas valve. The gas exits the gas outlet openings 25 for ignition and burning. With the combusting gas, the gas burner device 10 can be used for heating, for example, a saucepan or a baking oven, ie for cooking, alternatively for a Water boiler or the like .. The burner body 20 is formed of a conductive metal and is further grounded as a kind of ground terminal, so that a current can flow through it.

To ignite the gas flowing out of the gas outlet openings 20, an ignition electrode 30 is provided. In order to monitor the correct propagation of an ignited flame, a flame monitoring electrode 40 is further provided. As shown, the flame monitoring electrode 40 is spaced from the burner body 30 by distance D, and is thus farther from the ignition electrode 30 at a distance d from the burner body 30. It should be understood, however, that as shown in FIG Fig. 1 just a schematic view. In any case, the distance D is greater than the distance d, the difference may be at least 10% or 30%, and may be up to 100% or 200%.

The two electrodes 30, 40 are arranged so that the respective tips of the electrodes 30, 40 during operation of the gas burner device 10, i. essentially when a flame burns over the gas outlet openings 25, located in the flame. The flame monitoring electrode 40 is directly connected to an electrode terminal 60, i. without the interposition of any electrical or electronic components connected. The ignition electrode 30 is also connected to the electrode terminal 60. However, a spark gap 35 is located between the ignition electrode 30 and the electrode connection 60. The spark gap 35 has a first spark gap electrode 36, a second spark gap electrode 38 and a gas-filled discharge space 37 arranged therebetween. This could also be ambient air. The first spark gap electrode 36 is connected to the ignition electrode 30. The second spark gap electrode 38 is connected to the electrode terminal 60. The gas located between the spark gap electrodes 36, 38 ensures that, in the case of applied voltages which are lower than a breakdown voltage of the spark gap 35, a current flow between the spark gap electrodes 36, 38 is prevented. Even an applied voltage is not transmitted. Thus, in this case, the ignition electrode 30 remains de-energized and de-energized. Only when the applied voltage is higher than the breakdown voltage, the gas is ionized and the spark gap 35 is conductive. It could also, as mentioned above, several spark gaps can be provided.

The gas burner arrangement 5 furthermore has a control device 70 with an output 75. As shown, the electrode terminal 60 of the gas burner device 10 is connected to the output 75 of the controller 70.

The control device 70 has processor means and memory means (not shown), wherein program code is stored in the memory means and can be executed by the processor means. Thus, the controller may perform the functions described below.

When the gas burner arrangement 5 is to be put into operation, the control device 70 first of all ensures that combustible gas flows into the inlet 22 of the burner body 20 via valves, not shown, so that it exits from the gas outlet openings 25. Subsequently, the control device 70 applies an ignition voltage of 10 kV to the output 75. This voltage is much greater than the breakdown voltage of the spark gap 35, which in the present example is 400 V, which is why the ignition voltage reaches the ignition electrode 30. This ignition voltage is also greater than a breakdown voltage of the ignition electrode 30 to the burner body 20, so that between the ignition electrode 30 and the burner body 20, an arc is formed. However, the ignition voltage is lower than a breakdown voltage between the flame monitoring electrode 40 and the burner body 20, so that no arc is generated at the flame monitoring electrode 40.

By the arc just described between the ignition electrode 30 and the burner body 20, the gas flowing out of the gas outlet openings 25 is ignited. The control device 70 switches back after a defined period of time with applied ignition voltage, the voltage applied to the output 75, so that subsequently only a measurement voltage in the amount of 230 V is applied as an AC voltage at the output 75. This measurement voltage, even its maximum value of about 325 V, is smaller than the breakdown voltage of the spark gap 35, which may advantageously be just 400 V, so that the ignition electrode 30 is not reached by the measurement voltage. The measurement voltage thus reaches only the flame monitoring electrode 40.

When the flame ignited at the ignition electrode 30 propagates across the gas outlet openings 25 to the end of the burner body 20 opposite to the ignition electrode 30, the flame also reaches the flame monitoring electrode 40. In this case, due to the measurement voltage applied to the flame monitoring electrode 40, the flame flows through the flame , which contains a high concentration of ionized and thus conductive particles, a current via the burner body 20 to ground. The control device 70 can detect this current in order to recognize that the flame has spread correctly over the entire burner body 20, ie in particular over all gas outlet openings 25. In this case, the gas burner device 10 is operated further. Should, however, for example an undesirable object located on the burner body 20, which blocks a number of gas outlet openings 25, such as food particles, so the flame can not spread to the flame monitoring electrode 40. In this case, the already described ionized particles between the burner body 20 and the flame monitoring electrode 40 would be absent, so that no current flows through the flame monitoring electrode 40. This can be detected by the control device 70.

The control device 70 is configured to wait a certain period of time after the switchover from the ignition voltage to the measurement voltage, and then to check whether a current above the predetermined threshold value flows via the flame monitoring electrode 40. If this is the case, then the controller 70 detects that the flame has been ignited correctly and has spread over all the gas outlet openings 25. However, should the current not exceed the predetermined threshold value, then the control device 70 recognizes that the flame has not spread correctly or possibly has not even been ignited. In this case, the control device 70 switches off the gas supply to the gas inlet 22 of the burner body 20 for safety reasons.

The controller 70 may also be programmed to make a second attempt to ignite in this case, i. for a certain period of time applies the ignition voltage to the outlet 75. Then it can be checked again whether the flame has been ignited and spread properly. In addition, a warning message can be issued to a user.

The gas burner arrangement 5 according to the invention can thus be reliably operated autonomously, wherein a manual check as to whether the flame has been ignited and has spread out correctly can be dispensed with. There is no risk that, in the event of a misfire or if the flame propagation is blocked, flammable gas escapes uncontrollably from gas outlet openings 25, which can accumulate and lead to the risk of fire and explosion, or, alternatively, an incorrect power generation can simply be effected.

Claims (15)

A gas burner device (10), comprising: a burner body (20) with a number of adjacent gas outlet openings (25), an ignition electrode (30), a flame monitoring electrode (40), and a common electrical electrode connection (60) for the electrodes (30, 40) to a control device (70) of the gas burner device (10), wherein the ignition electrode (30) is connected to the electrode terminal (60) via at least one spark gap (35) and the flame monitoring electrode (40) is connected directly to the electrode terminal (60), - And wherein the ignition electrode (30) and the flame monitoring electrode (40) adjacent to the burner body (20) are arranged in such a way that the ignition electrode (30) has a smaller breakdown voltage to the burner body (20) out as the flame monitoring electrode (40). A gas burner device (10) according to claim 1, characterized in that the ignition electrode (30) has a different electrode tip than the flame monitoring electrode (40) to achieve the lower breakdown voltage of the ignition electrode (30), preferably a more pointed electrode tip. Gas burner device (10) according to claim 1 or 2, characterized in that the ignition electrode (30) is arranged at a smaller distance from the burner body (20) than the flame monitoring electrode (40) to achieve the lower breakdown voltage of the ignition electrode (30). Gas burner device (10) according to any one of the preceding claims, characterized in that the ignition electrode (30) has a distance of 3 mm to 5 mm from the burner body (20), preferably 4 mm. Gas burner device (10) according to any one of the preceding claims, characterized in that the flame monitoring electrode (40) has a distance of 5 mm to 7 mm from the burner body (20), preferably 6 mm. Gas burner device (10) according to any one of the preceding claims, characterized in that a spark gap (35) as a gas-filled discharge space (37) between a first spark gap electrode (36) and a second spark gap electrode (38) is formed, wherein the first spark gap electrode (36) the ignition electrode (30) is connected and the second spark gap electrode (38) is connected to the electrode terminal (60). Gas burner device (10) according to any one of claims 1 to 5, characterized in that a spark gap (35) is formed as an electronic component. Gas burner device (10) according to any one of the preceding claims, characterized in that the ignition electrode (30) and the flame monitoring electrode (40) are fixed to the burner body (20). Gas burner device (10) according to any one of the preceding claims, characterized in that the ignition electrode (30) and the flame monitoring electrode (40) opposite positions and / or at respective remote end portions lying positions on the burner body (20). Gas burner device (10) according to any one of the preceding claims, characterized in that the spark gap (35) has a breakdown voltage of 250 V to 450 V. A gas burner device (10) according to any one of the preceding claims, characterized in that the flame monitoring electrode (40) is arranged so that its tip is within a flame when the flame is burning on the gas burner device (10). A gas burner assembly (5), comprising: - A gas burner device (10) according to any one of the preceding claims, and a control device (70) having an output (75) which is designed to connect the electrode terminal (60) of the gas burner device (10),
wherein the control means (70) is adapted to output at the output (75) an ignition pulse having an ignition voltage higher than the breakdown voltage of the ignition electrode (30) to the burner body (20) and smaller than the breakdown voltage of the flame monitoring electrode (40) Torch body, and
wherein the control device (70) is designed to output at the output (75) a measuring voltage for detecting a flame burning at the gas burner device (10) which is smaller than the breakdown voltage of the spark gap (35). Gas burner arrangement (5) according to claim 12, characterized in that the ignition voltage is between 8 kV and 12 kV, preferably 10 kV. Gas burner arrangement (5) according to claim 12 or 13, characterized in that the measuring voltage is between 200 V and 260 V, preferably 230 V. Gas burner arrangement (5) according to any one of claims 12 to 14, characterized in that the control device (70) is adapted to output the ignition pulse for a defined period of time for igniting the gas burner device (10) and then to output the measurement voltage and thus to the gas burner device ( 10) to monitor burning flame.

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