Method and device for protecting a waste gas system of a heating device

Abstract

The invention relates to a method and a device for preventing damage to an exhaust system (10) of a heating appliance (1) caused by pressure pulses generated during ignition, wherein the heating appliance (1) has a burner (3) for combustion of fuel-air mixture in a combustion chamber (13) connected to the exhaust system (10) and an electronic unit (7) for automatic ignition, wherein a pressure sensor (6) for converting pressure pulses into electronic signals is arranged in the exhaust system (10) and wherein the pressure sensor (6) is connected to the electronic unit (7), which is configured to compare the electronic signals of the pressure sensor (6) with at least one threshold value and to count exceedances of the threshold value and to store them in at least one first counter (74) and to trigger a warning message and / or a shutdown of the heating appliance (1) when a predefinable counter value of the counter (74) is exceeded.Preferably, the electronic unit (7) also includes a limit value comparator (73) for comparing the electronic signals of the pressure sensor (6) with a predefinable limit value, wherein the electronic unit (7) is configured to switch off and / or switch off and lock the heating device (1) when the limit value is exceeded. The present invention increases the safety during the operation of heating devices by measuring and analyzing the actual frequency and intensity of pressure pulses in their exhaust system caused by ignition errors, but avoids unnecessary shutdowns in the case of only a few or weak pressure pulses.

Description

[0001] The invention relates to a method and a device for protecting an exhaust system of a heating appliance, in particular for preventing damage to an exhaust system of a heating appliance caused by pressure pulses generated during ignition.

[0002] Heating appliances for heating buildings and / or domestic hot water are typically installed in an accessible room, particularly a basement or utility room. It is crucial that no exhaust gases can enter the installation room or the building itself, as this could have adverse health consequences for anyone entering the installation room or elsewhere in the building. Therefore, a high degree of airtightness is required for such heating appliances. This applies especially to all components of the exhaust system, which must be installed and secured according to the relevant regulations.

[0003] JP 2012097932 A discloses a water heater with a function for detecting incomplete combustion in a burner. This includes a flame sensor for detecting the burner's combustion flame, and its detection signal is triggered when the burner is burning incompletely. This solution makes it possible to distinguish incomplete combustion from misfires caused by strong external wind. Furthermore, a counter can be provided that counts and stores the number of incomplete combustions by the burner, with a combustion suppression unit stopping the combustion process when a predetermined count is reached. However, this method does not provide a solution for preventing damage to a heating appliance's exhaust system caused by pressure pulses generated during ignition.

[0004] German patent DE 202013004336 U1 discloses an exhaust gas throttling device for a heating appliance, wherein the exhaust gas flow exiting the combustion chamber is throttled in order to retain the heat generated by combustion in the boiler for as long as possible and thus improve the transfer of the combustion heat to the heating fluid in the boiler. Due to the throttling, the pressure and simultaneously the temperature at the burner increase, which must not occur excessively. For this purpose, a pressure measuring device is provided for recording an actual pressure value relative to the combustion chamber, and a control unit is provided which communicates with the pressure measuring device and the burner, wherein the control unit is configured to switch off the burner if the actual pressure value exceeds a predetermined target pressure value.It is explained that during ignition to start the burner, a pressure surge can occur which should not lead to a shutdown, so the control unit should be designed so that an exceedance of the pressure value only leads to a shutdown after a certain time period after ignition and / or if it occurs over a certain period of time.

[0005] However, there are situations where pressure surges occur in the exhaust system, which can stress all components and especially their connections. For example, when igniting a burner, so-called hard ignitions can occur, where ignition happens so late after the fuel supply is opened that a certain amount of ignitable mixture has already accumulated in the combustion chamber or even in parts of the exhaust system. This then leads to a more or less severe type of deflagration upon ignition and causes pressure surges in the combustion chamber, the exhaust system, and all related systems.Such hard ignitions and other faults, which can occasionally occur in automatic ignition devices (ignition controllers) due to wear and tear or unfavorable operating conditions (humidity, air pressure, air temperature), generate undesirable noises and, if they occur repeatedly or particularly violently, can damage the exhaust system, especially if it is not or no longer properly secured. For example, the connections of nested pipe sections can become leaky. Various methods are known in the art for detecting and counting hard ignitions or other ignition faults and deriving warning signals or even shutdowns of the heating appliance from them. However, these known methods do not determine the precise strength of the pressure pulses in the exhaust system, leading to unnecessary shutdowns or premature warnings even though the integrity of the exhaust system is not (yet) compromised.

[0006] The object of the present invention is to at least partially solve the problems described with reference to the prior art and, in particular, to prevent damage to the exhaust system of a heating appliance with automatic ignition caused by hard ignitions and other faults that lead to pressure pulses. This should also avoid potentially unnecessary warning messages and / or shutdowns without compromising the safety of the exhaust system.

[0007] To solve this problem, a method, a device, and a computer program product according to the independent claims are provided. Advantageous embodiments and further developments of the invention are specified in the respective dependent claims. The description, particularly in conjunction with the drawing, illustrates the invention and provides further exemplary embodiments.

[0008] In a method for (largely) preventing damage to the exhaust system of a heating appliance caused by pressure pulses (primarily) generated during ignition, the pressure in the exhaust system is measured by means of (at least) one pressure sensor and converted into an electronic measurement signal, the magnitude of which is monitored and compared with at least one predefinable threshold value, the number of times the threshold value is exceeded is counted and stored in at least one counter, and depending on the counter reading, a warning message and / or a shutdown of the heating appliance is triggered.

[0009] The at least one pressure sensor can be in direct contact with the exhaust gas in the exhaust system. Alternatively, the pressure sensor can be located on the exhaust system, for example, separated from the exhaust gas by a membrane. It is also possible that the pressure sensor itself does not measure the pressure, but rather determines or records a value characteristic of the pressure in the exhaust system and outputs a pressure value of a suitable magnitude. The threshold value can be a fixed value stored in a memory, or it is possible that this predefined threshold value is (automatically) varied depending on an operating parameter of the heating appliance. Such operating parameters can include the fuel gas composition, temperature, noise level, operating hours, etc.The number of exceedances can be either fixed or (automatically) variable depending on the heating appliance's operating parameters, triggering a warning or shutdown if the number is lower or higher. The threshold, the number of exceedances, and / or the operating parameters can also be considered when deciding whether to initiate a warning and / or shutdown.

[0010] The best way to assess the magnitude and impact of pressure pulses on the exhaust system's integrity is by measuring the pressure within the system itself. Experience shows that damage is usually not caused by isolated events, but rather by a larger number of events, depending on their intensity. Not every hard ignition has the same effect. Therefore, it is advisable to count the events, specifically those that exceed a certain threshold.

[0011] However, even very intense individual events can cause damage. Therefore, in a specific embodiment, the magnitude of the measurement signal is also compared to a limit value, exceeding which triggers either an immediate or at least a shutdown of the heating unit, or a shutdown with interlock. The limit value represents a singular damaging event and is consequently higher than the threshold value. The limit value is set so that no damage can occur from individual events below it. A shutdown "with interlock" represents the highest level of safety. After a shutdown, the heating unit can only be restarted by qualified personnel following an inspection of the entire heating unit and the exhaust system, and, if necessary, repairs.

[0012] In a preferred embodiment, the magnitude of the measurement signal is compared to two or more threshold values ​​of varying magnitudes, and the number of times each threshold is exceeded is counted and stored in (separate or assigned) counters. Based on predefined criteria, a warning message and / or a shutdown (automatically) is triggered from the counter readings. This allows for differentiation between two or more categories of pressure pulses depending on their magnitude or intensity. Experience allows for the assessment of potential damage and / or maintenance intervals based on the frequency of events in each category and the definition of criteria for when warnings or shutdowns should occur. In this way, unnecessary actions are avoided without compromising the integrity of the exhaust system.

[0013] The absolute number of threshold exceedances and / or the number per predefined time interval can serve as criteria for a warning message or shutdown. Heating appliances are often checked at specific intervals, so that below a certain number of damaging events per time interval, no damage is expected until the next maintenance appointment. Thus, a warning message may be omitted even if the absolute number of damaging events would trigger one. Conversely, a warning message may be issued if the absolute number of damaging events is not yet high, but they occur in rapid succession. Combinations of both approaches are possible. The numbers to be assessed here are generally small, e.g., between 0 and 100, preferably between 0 and 10, and especially less than 5, because faulty ignitions, if they occur frequently, will in any case necessitate maintenance.

[0014] According to another aspect, a device is proposed for (largely) preventing damage to the exhaust system of a heating appliance caused (primarily) by pressure pulses generated during ignition. The heating appliance comprises a burner for combusting a fuel-air mixture in a combustion chamber connected to the exhaust system and an electronic unit for automatic ignition. A pressure sensor for converting pressure pulses into electronic signals is associated with the exhaust system and is connected to the electronic unit. The electronic unit is configured to compare the electronic signals from the pressure sensor with at least one threshold value and to record the number of times the threshold is exceeded in at least one counter, storing this data (temporarily). If a predefined counter value is exceeded, the electronic unit can (automatically or immediately) trigger a warning message and / or shut down the heating appliance.

[0015] Modern heating appliances have a central electronic unit that controls all functions and where the readings from multiple sensors converge. This unit typically contains a microprocessor, memory for calibration data, and a program to control all processes. This electronic unit can also perform the tasks described here for evaluating the signals from the pressure sensor in the exhaust system, or it can be equipped with an additional pressure analyzer for this purpose. Checking whether and how often a reading exceeds a specific threshold can be easily implemented in an electronic unit. It can also trigger a warning message or initiate a shutdown. A typical electronic unit is connected to a display and / or warning device (e.g., a user display), which can also be used to output warning messages and displays of the type described here.Remote transmission of such messages / indications to a central office or maintenance service is also possible.

[0016] Preferably, the electronic unit includes at least one threshold comparator for comparing the electronic signals of the pressure sensor with a predefinable threshold and at least one first counter for counting the detected exceedances.

[0017] In a preferred embodiment, and to increase safety, the electronic unit also includes a limit value comparator for comparing the electronic signals of the pressure sensor with a predefinable limit value. The electronic unit is configured to switch off and / or shut down and lock the heater if the limit value is exceeded. Certain pressure pulses exceeding the limit value are classified as so critical for the exhaust system that an immediate shutdown occurs after only one occurrence.

[0018] In a specific configuration, two or more threshold comparators with staggered thresholds and associated counters are present to count the exceedances of the respective thresholds by the electronic signals from the pressure sensor. This allows pressure pulses of varying intensities to be differentiated and classified into two or more categories, enabling a more precise assessment of potential damage to the exhaust system and helping to avoid unnecessary warnings or shutdowns. Staggered thresholds are thresholds of varying heights, ordered by magnitude, so that a first counter counts all pressure pulses above the first threshold, a second counter only those that also exceed a second, higher threshold, and so on, depending on the number of counters and categories.All threshold values ​​are below the limit, so if the limit is exceeded, all counters will also count the corresponding pressure pulse (which can be useful for a plausibility check).

[0019] In particular, the electronic unit is designed to determine the number of times a threshold value is exceeded within a predefined time interval and to use this number as an (additional) criterion for warning messages or shutdown. This allows for a particularly precise analysis of potentially recurring faults in the heating unit, enables early warnings of critical malfunctions, and avoids unnecessary actions. Thus, with just one pressure sensor in the exhaust system, a large amount of important information about the operation of the heating unit and any malfunctions can be obtained, while simultaneously protecting the exhaust system from damage.

[0020] Another aspect concerns a computer program product, comprising commands that cause the described device to execute the described procedure. The electronic unit requires a program and data for controlling the heating device and evaluating the signals from the pressure sensor, both of which must or may need to be updated occasionally.

[0021] The explanations of the method can be used to further characterize the device, and vice versa. The device can also be configured to carry out the method.

[0022] A schematic embodiment of the invention, to which it is not limited, and the functioning of the method will now be explained in more detail with reference to the drawing. The drawing shows: Fig. 1: schematically a heating device with pressure sensor, and Fig. 2: schematically a part of an electronic unit of a heating device with pressure sensor, namely the part in which signals from a pressure sensor are processed.

[0023] Fig. 1 Figure 1 schematically depicts a heating appliance 1 with an exhaust system 10, on or in which a pressure sensor 6 is arranged. The pressure sensor 6 is preferably located at a point where the exhaust gases have already cooled somewhat, particularly at an end section of the exhaust system 10. The pressure sensor 6 can be a differential pressure sensor or measure absolute pressure and convert it into electrical signals. In the heating appliance 1, air is drawn in from an air supply 4 by a blower 2 and conveyed to a burner 3. Fuel from a fuel supply 8 is mixed with the air via a fuel valve 5. The resulting fuel-air mixture, preferably a fuel gas-air mixture, where the fuel gas can also be or contain hydrogen, is ignited and burned in a combustion chamber 13 by means of an ignition electrode 12. The resulting exhaust gases transfer most of their heat to a heat exchanger 14 and are then discharged into the environment via an exhaust system 10.The exhaust system 10 can, for example, consist of several nested and fixed pipe sections, whereby the pipe connections 11 of the pipe sections are subjected to axial stress during pressure pulses inside the exhaust system 10, so that radial frictional forces can be exceeded and damage can occur if the pipe sections are not (or no longer) properly fixed. The present invention prevents this by means of the pressure sensor 6 on the exhaust system 10. The entire heating unit 1 is controlled and regulated by an electronic unit 7, which also processes data from various sensors, regulates the air supply and fuel supply based on calibration data, characteristic maps, and specifications, and performs automatic ignition and shutdown processes. In the event of faulty ignition processes, the deflagrations described above can occur in the combustion chamber 13 and the exhaust system 10, which can lead to pressure pulses of varying intensity.The electronic unit 7 is connected to a display 9 (or at least a warning device) from which a user can read the current status of the heating device 1 and the nature of any malfunctions. Remote transmission of data about the status of the heating device 1 is also possible. According to the invention, the electronic unit 7 is designed to also analyze and process the electronic signals from the pressure sensor 6, which is why the pressure sensor 6 is connected to the electronic unit 7 via a data connection 15.

[0024] Fig. 2This illustrates what happens to the data from the pressure sensor 6 in the electronic unit 7, shown here separately using a pressure analyzer 70, which can also be integrated into the rest of the electronic unit 7 and does not have to be a separate component. The data from the pressure sensor 6 first travels via the data connection 15 to a first threshold comparator 71, which, when a first threshold is exceeded, activates a first counter 74, causing it to increment by one unit. The data then travels to a second threshold comparator 72, which, when a second threshold is exceeded, activates a second counter 75, causing it to increment. Further threshold comparators (not shown here) with staggered thresholds can follow, depending on how precisely the data from the pressure sensor 6 needs to be analyzed. In this way, a kind of multi-channel analyzer can even be created for the magnitude of the pressure pulses in the exhaust system 10.Finally, the data from pressure sensor 6 are fed to a limit value comparator 73, which, if a limit value is exceeded, immediately triggers a shutdown by the electronic unit 7 via a shutdown signal transmitter 78, because damage to the exhaust system 10 could occur or have already occurred very soon above the limit value. The counter readings from the first 74 and second 75 counters (and any other counters that may be present) are evaluated in an evaluation unit 76, which, according to predefined criteria, issues a warning message to the warning device 9 via a warning message generator 77 or activates the shutdown signal transmitter 78 if criteria for a shutdown are met. Absolute counter readings and / or events counted per counter per unit of time can serve as criteria.In situations classified as safety-relevant, in addition to a shutdown, a so-called locking of the heating device 1 may also occur, which can then only be put back into operation by specialist personnel after inspection and, if necessary, repair.

[0025] The present invention increases the safety in the operation of heating appliances by measuring and analyzing the actual frequency and strength of pressure pulses in their exhaust system, but avoids unnecessary shutdowns. Reference symbol list

[0026] 1 Heater 2 Blower 3 Burner 4 Air supply 5 Fuel valve 6 Pressure sensor 7 Electronic unit 8 Fuel supply 9 Display, warning device 10 Exhaust system 11 Pipe connection 12 Ignition electrode 13 Combustion chamber 14 Heat exchanger 15 Data connection 70 Pressure analyzer 71 First threshold comparator 72 Second threshold comparator 73 Limit comparator 74 First counter 75 Second counter 76 Evaluation unit 77 Warning message generator 78 Shutdown signal transmitter

Claims

1. Method for preventing damage to an exhaust system (10) of a heating appliance (1) caused by pressure pulses arising during faulty ignition, characterised in that during ignition, pressure pulses are measured by means of a pressure sensor (6), pressure pulses are measured in the exhaust system (10) and converted into an electronic measurement signal, the magnitude of which is monitored and compared with at least one predeterminable threshold value, wherein furthermore the number of times the threshold value is exceeded is counted and stored in at least one counter (74, 75) and wherein, depending on the counter reading of the counter (74, 75) at least one warning message or a shutdown of the heating appliance (1) is triggered.

2. Method according to claim 1, wherein the magnitude of the measurement signal is also compared with a limit value, upon exceeding which the heating appliance (1) is switched off directly or switched off with interlocking.

3. Method according to claim 1 or 2, wherein the magnitude of the measured signal is compared with two or more threshold values graded in magnitude and the number of times the individual threshold values are exceeded is counted and stored in counters (74, 75), and wherein at least one warning message or a switch-off is triggered on the basis of prespecified criteria from the counter readings of the counters (74, 75).

4. Method according to one of claims 1 to 3, wherein at least the absolute number of exceedances of a threshold value or the number per predeterminable time interval serves as a criterion for a warning message or shutdown.

5. Device comprising at least one electronic unit and a pressure sensor, designed to prevent damage to an exhaust system (10) of a heating appliance (1) caused by pressure pulses arising during faulty ignition, wherein the heating appliance (1) has a burner (3) for burning a fuel-air mixture in a combustion chamber (13) connected to the exhaust system (10) and the electronic unit (7) being designed for automatic ignition, characterised in that the pressure sensor (6) for converting pressure pulses into electronic signals is assigned to the exhaust system (10), and wherein the pressure sensor (6) is connected to the electronic unit (7), which is further designed to compare the electronic signals of the pressure sensor (6) with at least one threshold value during ignition and to count exceedances of the threshold value and to store them in at least one first counter (74) and, when a predeterminable counter reading of the counter (74) is exceeded, to cause at least one warning message or a shutdown of the heating appliance (1).

6. Device according to claim 5, wherein the electronic unit (7) has at least one first threshold value comparator (71) for comparing the electronic signals of the pressure sensor with a preset first threshold value and at least one first counter (74) for counting the detected exceedances.

7. Device according to claim 5 or 6, wherein the electronic unit (7) has a limit value comparator (73) for comparing the electronic signals of the pressure sensor (6) with a preset limit value, wherein the electronic unit (7) is designed to at least switch off or switch off and lock the heating appliance (1) when the limit value is exceeded.

8. Device according to one of claims 5 to 7, wherein two or more threshold value comparators (71, 72) with staggered threshold values and associated counters (74, 75) are provided for counting the number of times the respective threshold values are exceeded by the electronic signals of the pressure sensor (6).

9. Device according to one of claims 5 to 8, wherein the electronic unit (7) is designed to determine the number of times a threshold value is exceeded per presettable time interval and to use this number as a criterion for warning messages or a shutdown.

10. Computer program product comprising instructions that cause the device according to any of claims 5 to 9 to carry out the method according to any of claims 1 to 4.

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