Method for controlling the start of a heating device with a burner

Abstract

The invention relates to a method for controlling the start of a heating device (12) with a burner (13) and a combustion chamber (20), to which combustion air and fuel gas are supplied as a mixture via a supply channel, which includes an ignition device (14) for a fuel gas-air mixture and a control unit (15), wherein the method comprises at least the following steps: a. Performing a start sequence comprising a plurality of predetermined ignition parameter settings (1, 2, 3, 4, 5) which are activated successively, b. Identifying the ignition parameter setting (1, 2, 3, 4, 5) that caused successful ignition, and c. Determining the sequence of the predetermined ignition parameter settings (1, 2, 3, 4, 5) for a subsequent start sequence. Furthermore, a control unit (15) for controlling the method and a computer program for executing the control of the method are proposed.

Description

[0001] The invention relates to a method for controlling the start-up of a heating appliance with a burner. Furthermore, a heating appliance with a control unit for controlling the method and a computer program for executing the control by the control unit of the heating appliance are provided.

[0002] The start-up of a heating appliance with a burner is subject to various environmental fluctuations, including at least variations in intake air temperature, gas pressure, and / or changes in installation conditions. The combination of these factors can lead to (unexpected) noises and / or delays during the start-up phase. Disturbing noises are primarily caused by uncontrolled ignitions when starting with an incorrectly set fuel-air mixture composition, specifically one with an excessively high proportion of fuel gas. Ignition delays can occur if the fuel-air mixture contains too much air during start-up. Such events during the start-up of a heating appliance can reduce its robustness and / or lead to its failure.

[0003] Especially when such problems occur, it is difficult to quickly and correctly initiate countermeasures that lead to stable ignition. If this is not achieved quickly enough, a user who, for example, wants heated domestic hot water cannot access it quickly enough and thus experiences a loss of comfort.

[0004] Furthermore, the initial setup of a heating appliance with regard to suitable ignition conditions is time-consuming, e.g., setting new ignition conditions and / or storing them in the appliance. This can make the installation of such systems time-consuming, expensive, or even prone to malfunctions. For example, EP 3 301 365 A1 discloses a complex method for controlling an ignition operation, in which an operating characteristic value is recorded before the ignition operation, which is suitable for determining the quality of the fuel used in the heating system.

[0005] DE 196 05 324 C1 describes a method for operating an auxiliary vehicle heater in which operating parameters are recorded and the control unit adapts a start procedure based on these parameters. A disadvantage is that only limited conclusions can be drawn from operating parameters regarding suitable start procedure settings. DE 196 05 216 A1 also describes a method for operating an auxiliary vehicle heater. To increase operational reliability, it is proposed that the ignition device be operable in at least two different power levels. This method is also complex.

[0006] It is therefore an object of the invention to at least alleviate the problems described with reference to the prior art. In particular, it is an object of the invention to ensure that a heating device can be started (quickly) without disturbing noises and / or undesirable delays, so that its robustness is increased and / or a failure can be prevented.

[0007] This problem is solved according to the features of claim 1. Advantageous embodiments are specified in the dependent claims. The description, particularly in conjunction with the figures, explains the invention and also discloses additional embodiments of the invention.

[0008] A method for controlling the start of a heating appliance with a burner and a combustion chamber, to which combustion air and fuel gas are supplied as a mixture via a supply channel, contributes to solving this problem. The heating appliance also includes an ignition device for a fuel gas-air mixture and a control unit. The method comprises at least the following steps: a. Performing a start sequence comprising a plurality of predetermined ignition parameter settings that are activated sequentially, b. Identifying the ignition parameter setting from the plurality of predetermined ignition parameter settings that caused a successful ignition, and c. Determining the sequence of the predetermined ignition parameter settings for a subsequent start sequence.

[0009] The aforementioned steps a., b., c. can be carried out in the specified order, but this is not mandatory. In particular, it is possible that the steps overlap at least partially in time, are carried out at different locations with a time difference, and / or are repeated a different number of times.

[0010] The control system for starting a heating appliance with a burner can influence the ignition parameters of the air supply, the fuel gas supply, and / or the ignition by an ignition device in a time-dependent manner. The ignition parameters are preset in an ignition parameter setting, where a specific time sequence of the ignition parameters is defined.

[0011] The ignition device enables the ignition of a mixture of air and fuel gas supplied there, e.g., by means of a spark. The ignition device can be located in a combustion chamber of the burner of the heating appliance.

[0012] The control unit influences the amount of supplied air and / or fuel gas as well as the timing of the ignition spark. The control unit is configured to activate the ignition device.

[0013] The start sequence according to step a. is executed by the control unit sequentially activating predetermined ignition parameter settings. The order of the ignition parameter settings is predefined. The ignition parameter settings may differ in their characteristics, but may also have the same characteristics.

[0014] A start sequence comprises, for example, at least three or at least five predetermined ignition parameter settings, which are also executed in a predetermined order. The start sequence is executed by setting the first ignition parameter (also called the start ignition parameter setting) and activating the ignition device. If successful ignition is not detected, the system automatically proceeds to the next ignition parameter setting and activates the ignition device. Should this also fail to produce a stable flame, the system continues with the next ignition parameter setting, and so on.

[0015] Step a. is completed when an ignition parameter setting has led to a stable ignition of the fuel gas-air mixture or when ignition has been "successful".

[0016] The identification of the ignition parameter setting according to step b., which causes successful ignition, takes place at the end of, or after, the execution of the start sequence or step a. The control unit checks for the presence of a flame in the burner, for example, using a sensor or flame detector. The currently active or successful ignition parameter setting can be marked.

[0017] According to step c, the sequence of predetermined ignition parameter settings for a subsequent start sequence is determined based on the result of step b.

[0018] If step b identifies that the first ignition parameter setting (start ignition parameter setting) resulted in a successful ignition, step c can specify that the next start sequence (step a) will also begin with the same first ignition parameter setting. Conversely, if step b identifies that the second (or a subsequent) ignition parameter setting, rather than the first, resulted in a successful ignition, step c can specify that the second (or subsequent) ignition parameter setting will then be used as the first ignition parameter setting in the next start sequence (step a). In this case, it is particularly possible for both ignition settings to swap places in the sequence and / or for the newly successful ignition parameter setting to be placed before all others.It is possible to pre-select particularly promising ignition parameter settings, especially those determined in step b., several times in step c. and / or to execute them more frequently.

[0019] In particular, the predetermined ignition parameter settings are not adjusted themselves, but the majority of such stored or retrievable ignition parameter settings are only rearranged.

[0020] Such an ignition parameter setting can include ranges of variation that may take into account, for example, an ignition time, a stabilization time and / or a heating power.

[0021] The ignition time specifically comprises the period during which the ignition device emits a spark at predetermined intervals. The supply of fuel gas and air can be kept constant or varied during the ignition time. The ignition time ends with successful ignition and / or after reaching the predetermined ignition parameter setting.

[0022] The ignition time is preferably at least 0.5 to 5.0 s [seconds], and particularly 1.5 to 2.5 s. The range proposed here allows for robust ignition with a low risk of multiple ignitions. A firing time of 1.5 to 2.0 s is especially preferred. If the lower limit is undershot, there is a risk of multiple ignitions occurring later in the ignition phase, including undesirable noise generation. If the upper limit is exceeded, successful ignition can no longer be guaranteed.

[0023] The ignition device preferably emits ignition sparks at intervals of at least 30 to 250 ms (milliseconds) or 4 to 30 Hz during the ignition period. The range proposed here ensures a high availability of an ignition source within the available ignition time. Most preferably, the ignition device emits ignition sparks at intervals of 40 to 60 ms during the ignition period. If the lower limit is not met, there is a risk that a slightly delayed ignition will lead to increased noise levels. If the upper limit is exceeded, it can lead to a reduction in the service life of the components.

[0024] The stabilization period encompasses the time immediately following the ignition and after successful ignition. During this period, the burner checks whether the flame is stable after successful ignition. Further adjustments to the ignition spark, fuel gas, and / or air may be made during the stabilization period. The stabilization period can also be considered part of step a.

[0025] The stabilization time is preferably at least 3.0 s [seconds]. The range proposed here allows for flame stabilization in the burner. A stabilization time of 0 to 5.0 s is particularly preferred. If the lower limit is not met, there is a risk that a stable flame will not be generated in the burner, potentially leading to flame extinguishment or a deflagration. If the upper limit is exceeded, the heating appliance will be unusable for too long after start-up, negatively impacting user-friendliness. Domestic hot water operation without loss of comfort is only possible after a stabilization period.

[0026] Once the flame has (successfully) stabilized, the system can switch to normal control / modulation, which then constitutes the regular operation of the heating appliance. In normal operation, control and regulation are carried out, for example, based on the (heating) demand of the connected domestic hot water system.

[0027] At least one of the ignition parameter settings includes a varying fuel-air mixture composition. "Varying" in this context means, in particular, that at least one ignition parameter is changed over time with a predetermined ignition parameter setting. The time-varying ignition parameter can be selected from the following group: fuel supply (or valve opening), air supply (or fan speed), ignition energy. The ignition parameter settings can characterize or define the fuel-air mixture composition.

[0028] The ignition parameter settings can determine the increase in the proportion of fuel in the fuel-air mixture over time. This increase does not have to be constant, but can occur in steps or with ramps, or even be quadratic.

[0029] The variation ranges of subsequent ignition parameter settings can partially overlap. Overlap occurs when the successively activated ignition parameter settings encompass situations with identical ignition parameters, particularly the same fuel-air mixture composition. For example, if an ignition parameter is varied from 100% to 120% in a first ignition parameter setting, partial overlap occurs if the subsequent ignition parameter setting varies the ignition parameter from 110% to 130%.

[0030] For step c, it is possible to consider in which section of the variation range the successful ignition was detected. The variation range of the ignition parameter can be divided into different sections. It is possible to record in which section, within the specified ignition parameter setting, the ignition occurred. This information can also be used to determine the sequence for the next start.

[0031] The control unit records measured values ​​from the start-up sequence until the ignition parameter setting is successfully established. It may also determine values ​​for ignition parameter settings that occurred before and / or after the successful ignition parameter setting. Furthermore, it can register the precise time during the successful ignition parameter setting period when the burner ignited.

[0032] In step c, a previous ignition parameter setting can be set as the starting ignition parameter setting if successful ignition was observed in an initial section of the variation range and the previous ignition parameter setting exhibited a leaner fuel-air mixture composition. The burner ignition occurred in a lean region of the ignition parameter setting. This region may overlap with or be close to a rich region of the previous ignition parameter setting. Therefore, a burner start sequence can very likely be achieved with the previous ignition parameter setting on the next start, ensuring reliable burner ignition.

[0033] In step c, the same ignition parameter setting can be set as the starting ignition parameter setting if successful ignition was detected in a central section of the variation range. The burner ignition thus occurred in a middle section of the ignition parameter setting. The ignition parameter settings are designed, for example, so that the central sections do not overlap with the variation ranges of the preceding and subsequent ignition parameter settings.

[0034] In step c, a subsequent ignition parameter setting can be designated as the starting ignition parameter setting if successful ignition was observed at the end of the variation range and the subsequent ignition parameter setting exhibited a richer fuel-air mixture composition. The burner ignition thus occurred within a richer range of the ignition parameter setting. This range may overlap with or be close to a leaner range of the subsequent ignition parameter setting. Therefore, a successful burner start sequence can very likely be achieved with the subsequent ignition parameter setting on the next start, ensuring reliable ignition.

[0035] An initial start sequence following the initial power-up of the heater features multiple predetermined ignition parameter settings, with the successively activated settings resulting in a richer fuel-air mixture. This initial start sequence is characterized by a set of ignition parameter settings pre-defined and stored by the heater manufacturer and / or the control unit. This applies to the initial startup of the heater after installation. The control unit may provide at least three ignition parameter settings for this purpose, with the lambda value being reduced with each subsequent setting.

[0036] The sequence of activated ignition parameter settings, or the determination of the sequence of predetermined ignition parameter settings for a subsequent start sequence, can be adjusted taking environmental parameters into account. In other words, the procedure can detect and consider the specific values ​​of environmental parameters present before and / or during ignition. These can then be used, for example, before step a. and / or during step c., to (re)define the sequence of predetermined ignition parameter settings for the (immediately) subsequent start sequence.

[0037] The environmental parameters can be selected from the following group: outside temperature, humidity, time until the last start-up of the heating unit (over the night and / or over the summer), fuel composition, burner temperature (heating unit still hot after only a short switch-off time).

[0038] During the stabilization period following a successful ignition attempt, the burner's flame behavior can be evaluated, and any flame behavior errors can be taken into account in step c. Flame behavior errors can manifest as a deflagration or an uncontrolled flame extinguishment. For example, an ignition parameter setting that might lead to an unstable flame can be postponed or not prioritized when determining the new sequence of ignition parameter settings.

[0039] In step c., at least one of the ignition parameters of the ignition parameter setting determined in step b. can be adjusted. For example, the time-dependent change of the ignition parameter in this ignition parameter setting can be (permanently) adjusted or saved and used for subsequent start sequences.

[0040] Sections of the ignition parameter setting range where successful ignition has been observed can be modified by varying the slope. This slope variation can reduce the rate of change in the fuel-air mixture composition, thus preventing an excessively high fuel-air ratio that could lead to a deflagration. This can be achieved by reducing the slope of the variation range just before the expected successful ignition point. This allows the critical range, where ignition can occur, to be traversed more slowly and with greater reliability.The described slope variation is particularly advantageous when a subsequent ignition parameter setting is defined as the starting ignition parameter setting, and when successful ignition has been determined in an end section of the variation range of this starting ignition parameter setting. In this case, the initial and / or middle sections could be changed or traversed more quickly, and the final section (significantly) more slowly.

[0041] Furthermore, a heating appliance contributes to solving the task. This appliance includes a burner and a combustion chamber to which combustion air and fuel gas are supplied as a mixture via a supply channel. It also features an ignition device for a fuel gas-air mixture and a control unit adapted to execute the steps of the process. The heating appliance can receive information about the flame behavior and control the air supply, the fuel gas supply, and the ignition device. The heating appliance can be part of a building's domestic hot water system or be specifically designed and configured for this purpose.

[0042] The heating appliance includes, in particular, a burner that can heat a domestic hot water system. The combustion chamber has an intake channel through which combustion air and (gaseous) fuel can be supplied as a mixture, and an exhaust channel through which combustion gases can be discharged. An ignition device ignites the mixture in the burner. The control unit can be integrated into the heating appliance.

[0043] Furthermore, a computer program contributes to solving the task by providing comprehensive commands that cause the heating device to execute the process steps. The computer program can receive, store, and / or process information / data or (determined and / or measured) value parameters about the flame behavior from the heating device.

[0044] The invention and its technical context are explained in more detail below with reference to four figures. The illustrations are schematic and not intended to demonstrate scale relationships. The explanations given with reference to individual details of the figures can be extracted and freely combined with information from the preceding description, unless a person skilled in the art would necessarily conclude otherwise, or such a combination is explicitly excluded. The figures schematically show: Fig. 1 : a graphical view of an exemplary process flow with two start sequences and five ignition parameter settings Fig. 2 : a graphical representation of an example of an initial ignition parameter setting Fig. 3 : a graphical representation of an example of a second ignition parameter setting Fig. 4 : schematic representation of a heating device with connected control and regulation unit.

[0045] Fig. 1 shows a graphical view of an exemplary process flow with two start sequences and five ignition parameter settings each.

[0046] It shows (above) an initial start sequence 6 and a subsequent start sequence 7 below, in which the ignition parameter settings, which show a fuel-air mixture composition with an increasing fuel content, were rearranged after the procedure was carried out. This will now be explained.

[0047] During the initial start sequence 6, the control unit of the heating device accesses a predetermined sequence of ignition parameter settings and is configured to execute them in the initial order: first ignition parameter setting 1, second ignition parameter setting 2, third ignition parameter setting 3, fourth ignition parameter setting 4 and fifth ignition parameter setting 5 (compare step a. of the procedure).

[0048] An initial ignition attempt was unsuccessful with the first ignition parameter setting 1, followed by an ignition attempt 8 with the second ignition parameter setting 2. This was determined as part of step b of the procedure.

[0049] In step c of the procedure, a new sequence was established, such that the second ignition parameter setting, 2, has the highest priority and is placed first in the next start sequence. It was even stipulated that the highest priority ignition parameter setting should be executed several times before any further ignition parameter setting is considered.

[0050] For the subsequent start sequence 7, the ignition parameter settings were reordered, with the second ignition parameter setting 2 now being placed at the beginning and executed twice. If no ignition occurs in the two attempts with the second ignition parameter setting 2, a third attempt follows with the first ignition parameter setting 1, followed by attempts with the second ignition parameter setting 2 and the third ignition parameter setting 3.

[0051] Fig. 2 Figure 1 shows a graphical representation of an example of a first ignition parameter setting 1. The first ignition parameter setting 1 comprises a varying fuel-air mixture composition with an increasing fuel fraction. During this increase, an ignition event 8 occurs. An ignition time 9 elapses before ignition 8. This is followed by a stabilization time 10. The stabilization time 10 features a smooth transition to a control / modulation phase 11. During the stabilization time 10 and the smooth transition to the control / modulation phase 11, the fuel fraction increases to a maximum, after which it remains constant.

[0052] Fig. 3 Figure 2 shows a graphical representation of an exemplary second ignition parameter setting 2. The second ignition parameter setting 2 has a slope variation of the varying fuel-air mixture composition with increasing fuel content, in which the slope of the second ignition parameter setting 2 is reduced before an expected ignition 8 (due to the determination in step b. of the previous start sequence).

[0053] Fig. 4Figure 1 shows a schematic representation of a heating appliance 12 with an attached control unit 15 and computer programming / network 17. The heating appliance 12 has a heat exchanger, from which the heat generated by a burner 13 is transferred to a line of a domestic hot water system or a heating system 16. The burner 13 has a combustion chamber 20. The combustion chamber 20 has a combined ignition device 14, here with combined flame monitoring. The ignition device 14 and the flame monitoring are controlled by the control unit 15. The ignition device 14 can ignite a mixture in the combustion chamber 20, and the flame monitoring 14 can monitor the maintenance of the ignited flame in the combustion chamber 20.

[0054] An exhaust pipe 19 is connected to the combustion chamber 20, which releases exhaust gases into the environment via an exhaust system 24.

[0055] A feed device 21 is connected to a burner door 27 of the combustion chamber 20. The feed device 21 is controlled by a speed controller 23, which in turn is controlled by the control unit 15. A mixture channel 25 is located upstream of the feed device 21. Fuel and combustion air are mixed in the mixture channel 25.

[0056] Fuel is supplied via a gas valve 22 located upstream of the mixture channel 25, which is controlled by the control unit 15. The gas valve 22 receives fuel via a gas supply 28. Combustion air is supplied to the mixture channel 25 via a combustion air supply 18. A mass flow sensor 26 is located in the combustion air supply 18.

[0057] A computer program / network 17 is connected to the control unit 15. The computer program 17 controls the control unit 15 and provides information from the network 17, which is incorporated into the control of the control unit 15. Information from the network 17 includes, for example, environmental parameters that can be selected from the following group: outside temperature, humidity, time until the last start-up of the heating unit 12 (overnight and / or over the summer), fuel composition in the conveying device 21, temperature of the burner 13 (heating unit 12 still hot after only a short shutdown period). Reference symbol list

[0058] 1. First ignition parameter setting 2. Second ignition parameter setting 3. Third ignition parameter setting 4. Fourth ignition parameter setting 5. Fifth ignition parameter setting 6. Initial start sequence 7. Subsequent start sequence 8. Ignition 9. Ignition time 10. Stabilization time 11. Control / Modulation 12. Heater 13. Burner 14. Ignition device 15. Control and regulation unit 16. Domestic hot water / heating system 17. Computer programming / network 18. Combustion air supply 19. Exhaust pipe 20. Combustion chamber 21. Conveyor device 22. Gas valve 23. Speed ​​controller 24. Exhaust system 25. Mixture channel 26. Mass flow sensor 27. Burner door 28. Gas supply

Claims

1. Method for controlling the start-up of a heating appliance (12) with a burner (13) and a combustion chamber (20) to which combustion air and fuel gas are supplied as a mixture via a supply channel, further comprising an ignition device (14) for a fuel gas-air mixture and a control and regulation unit (15), wherein the method comprises at least the following steps: a. Executing a start-up sequence comprising a plurality of predetermined ignition parameter settings (1,2,3,4,5) , which are activated sequentially, b. identifying the ignition parameter setting (1, 2, 3, 4, 5) from the plurality of predetermined ignition parameter settings (1, 2, 3, 4, 5) that causes successful ignition (8), and c. establishing the sequence of the predetermined ignition parameter settings (1,2,3,4,5) for a subsequent start sequence.

2. Method according to the preceding claim, wherein at least one of the ignition parameter settings (1, 2, 3, 4, 5) comprises a varying fuel gas-air mixture composition.

3. Method according to the preceding claim, wherein the variation ranges of subsequent ignition parameter settings partially overlap each other.

4. Method according to one of the preceding claims 2 or 3, wherein for step c., the section of the variation range in which successful ignition (8) was determined is taken into account.

5. Method according to one of the preceding claims 2 to 4, wherein - in step c., a previous ignition parameter setting is defined as the start ignition parameter setting if the successful ignition (8) was detected in an initial section of the variation range and the previous ignition parameter setting had a leaner fuel-air mixture composition, - in step c., the same ignition parameter setting is defined as the start ignition parameter setting if successful ignition (8) was determined in a central section of the variation range, and / or - in step c., a subsequent ignition parameter setting is set as the start ignition parameter setting if successful ignition (8) was determined in an end section of the variation range and the subsequent ignition parameter setting exhibited a richer fuel-air mixture composition.

6. Method according to one of the preceding claims, wherein an initial start sequence (6), following an initial switch-on of the heating appliance (12) comprises a plurality of predetermined ignition parameter settings (1, 2, 3, 4, 5), wherein the ignition parameter settings activated in succession comprise a richer fuel-air mixture composition.

7. Method according to one of the preceding claims, wherein a sequence of the activated ignition parameter settings is adjusted taking into account environmental parameters.

8. Method according to the preceding claim, wherein the environmental parameters are selected from the group consisting of outside temperature, humidity, time elapsed since the last start-up of the heating appliance, fuel composition, burner temperature.

9. Method according to one of the preceding claims, wherein the flame behaviour of the burner is evaluated during a stabilisation period (10) after a successful ignition attempt and errors in the flame behaviour are taken into account in step c.

10. Method according to one of the preceding claims, wherein in step c. at least one of the ignition parameters is adjusted to the ignition parameter setting determined in step b.

11. Heating appliance (12) with a burner (13) and a combustion chamber (20), to which combustion air and fuel gas are supplied as a mixture via a supply channel, further comprising an ignition device (14) for a fuel gas-air mixture and a control and regulation unit (15) designed to carry out the steps of the method according to claim 1.

12. Computer program product comprising instructions that cause the heating appliance (12) of claim 11 to execute the method steps according to one of claims 1 to 10.

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