Method for starting up a heating device, computer program, control and control device, heating device and use of a parameter

Abstract

A method is proposed for detecting an irregular ignition process of a heating device (1), comprising a blower (2) and a speed control (6) for adjusting the speed (11) of the blower (2), designed to convey a mass flow of a mixture of fuel and combustion air to a burner (3) of the heating device (1), wherein during commissioning a pulse width modulated signal is detected as a control signal (10) of the speed control (6) and an irregular ignition process is detected by evaluating the control signal (10).

Description

[0001] The invention relates to a method for detecting an irregular ignition process, in particular during the commissioning of a heating device, a computer program, a control and regulating device, a heating device and the use of a parameter.

[0002] A wide variety of heating appliances are known that burn a mixture of a fuel, especially gas or hydrogen, and ambient air in a combustion chamber to generate heat for supplying a building or for providing hot water.

[0003] When such heating appliances are put into operation, a conveying device, usually a blower, is regulated to a set output, thus adding or metering the fuel to a conveyed volume flow of drawn-in combustion air. The combustion mixture is then fed to a burner of the heating appliance, often with the assistance of the conveying device, and ignited by an ignition device, such as a spark or glow plug.

[0004] Irregularities in the fuel supply and / or composition of the combustion mixture, or a delayed ignition spark, can lead to problems. In particular, an excessively high fuel content in the mixture is a common cause and can lead to a so-called "hard ignition." This can manifest as an explosive noise and may also damage the heater or its components. In addition to the reduced comfort due to the noise, a hard ignition can therefore result in damage to components.

[0005] According to current technology, the occurrence of this problem can be recognized by the user and reported to a specialist company that can carry out maintenance and inspection of the heating appliance. However, this unfortunately often proves impossible, as, for example, no one is present to recognize the audibly unusual ignition, leading to a high risk of damage to the heating appliance, which can then result in a breakdown (fault shutdown). Furthermore, after an unsuccessful (hard) ignition attempt, the heating appliance may attempt to ignite again, thus increasing the risk of damage.

[0006] EP 3 581 850 A1 proposes detecting a faulty ignition during burner start-up using the control device. This involves recording the fan speed and comparing it to a stored and expected profile, thus identifying a faulty ignition. The proposed method with a regulated fan speed appears problematic because the fan speed is influenced by the speed control system, potentially complicating and delaying the comparison with a stored signal.

[0007] EP 3 919 817 A1 also proposes a method and a device for detecting faults during burner ignition. In this method, the fan speed and the fuel valve position are monitored during burner start-up, and characteristic changes are recorded to detect an ignition fault. Here, too, interference with the speed control can make it more difficult and delay the detection of an irregular ignition process.

[0008] DE 10 2010 056 275 A1 discloses a method for operating a gas burner in which a comparison of the current blower speed via the current PWM signal with a predefinable target blower speed or a target PWM signal is integrated into a start sequence.

[0009] Based on this, the object of the invention is to propose a method for commissioning a heating device that at least partially overcomes the problems of the prior art described above. In particular, problems during commissioning should be detected automatically, quickly and with a high degree of reliability, and a further ignition attempt should be prevented.

[0010] Furthermore, the invention should not significantly increase the complexity of a heating device, should require only minor structural changes to a heating device, and should allow for easy integration into an existing production process.

[0011] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0012] This is achieved by a method for detecting an irregular ignition process, possibly also during commissioning, of a heating device, wherein the heating device has a blower and a speed control for adjusting the speed of the blower, configured to convey a mass flow of a mixture of fuel and combustion air to a burner of the heating device, wherein during the ignition process a pulse width modulated (PWM) signal is monitored or recorded as a control signal of the speed control and an irregular ignition process is detected by evaluating the control signal by considering the control signal and its change over time.

[0013] This method is used to detect irregular ignition in a heating appliance, particularly so-called "hard" ignition, i.e., an explosive ignition process, also known as a deflagration, especially triggered by an excessively high fuel content in the fuel-air mixture supplied to the burner, i.e., with a lambda value close to or even below 1, or triggered by a delayed ignition spark, particularly in conjunction with a low lambda value. Irregular ignition is generally accompanied by a delayed ignition of the combustion mixture introduced into the combustion chamber and can cause a deflagration or even a flashback.

[0014] The procedure can be carried out in particular during each ignition process of a heating device in order to monitor it for irregularities.

[0015] The heating appliance is specifically designed to burn a liquid and / or gaseous fuel (such as heating oil, natural gas, or hydrogen) with the addition of ambient air and to generate thermal energy, for example, to heat a heat transfer fluid in a heating circuit or to provide hot water. In particular, the heating appliance may be a condensing boiler. The heating appliance typically has a combustion chamber and a conveying system (including a fan) that can transport a mixture of fuel and combustion air into the combustion chamber via a mixture channel. The combustion products can then be discharged through an exhaust duct of the heating appliance into a flue system.

[0016] When the heater is started up, the blower can be preset to a (predefined) target speed suitable for ignition via a pulse-width modulated signal from a (blower-specific or higher-level) speed control system. Subsequently, the appropriate amount of fuel for starting is added to the mass flow of combustion air delivered by the blower. In the case of a gaseous fuel, this can be supplied via a gas valve. The fuel-combustion air mixture can then be ignited by an igniter (spark igniter, glow plug).

[0017] The pulse-width modulated (PWM) signal can be a square wave that oscillates between two voltage levels. When controlling a (blower) motor with a PWM signal, the lower voltage level is typically 0V [volts], and the upper voltage level can be a rated voltage (corresponding to the motor's rated power). The time it takes for the upper and lower voltage levels to switch successively can be called a period. In a PWM signal, the period of the upper voltage level can be called ton, and the period of the lower voltage level can be called toff.

[0018] In other words, the PWM signal allows the blower to be switched on and off in rapid succession, resulting in a desired average speed (power). A PWM signal is often specified as a percentage (of the blower's rated power, for example), where the percentage value indicates the percentage of time the upper voltage level of the signal is present. Typically, with successful (normal) ignition, the PWM signal only needs to be increased slightly to maintain the desired operating point of the blower. With a hard ignition, the (abrupt) change in the PWM signal generated by the controller is much larger. If no flame is ignited, the PWM signal remains almost constant (which aids in troubleshooting).Thus, after carrying out a procedure proposed here, a successful (normal), a hard (with deflagrations) and / or a lack of flame formation during an ignition process can be detected by evaluating the PWM signal (optionally).

[0019] It is assumed that in the event of an irregular ignition process, such as an explosive event during ignition, the blower is affected by a pressure pulse (pressure change, pressure wave) propagating through the mixture channel (and exhaust channel / exhaust system), causing its speed to change (abruptly). The blower's speed control attempts to counteract this change in speed by modifying a pulse-width modulated control signal (automatically or immediately and / or depending on the changed flow conditions). This change can be monitored using the method proposed here and used to detect an irregular ignition process.

[0020] Advantageously, monitoring, acquiring, and evaluating a PWM signal from a speed controller allows the controlled system (through the speed controller's design) to be taken into account. Evaluating the speed controller's response to a load change provides additional information about the ignition process, for example, in comparison to an evaluation of the fan's speed signal. It is possible to adapt the signal to the specific application using a suitable routine or data analysis, allowing the signal's sensitivity or waveform to be adjusted to achieve the desired result.

[0021] Even during a regular ignition process, a pressure pulse can occur; however, this can be distinguished from an irregular ignition process by quantitative analysis and / or by observing changes in the control signal over time. Thus, by examining the control signal and its changes over time, a regular ignition process can be reliably distinguished from an irregular one.

[0022] The speed controller can be designed, in particular, to regulate the power (especially the speed of a blower) of the conveying device or the blower to a predetermined value.

[0023] According to an advantageous embodiment, an irregular ignition process can be assumed if the PWM signal undergoes a (sudden) change of at least 10% [percent (of the rated fan power)], 20%, or 30% during the ignition process of the heater's start-up. The specific value can depend on various characteristics of the heater, whereby the value for a regular ignition process can be easily determined, thus allowing for a straightforward distinction.

[0024] According to an advantageous embodiment, an irregular ignition process can also be detected by considering the time derivative (gradient or transient) of the duration tin and / or tout of the PWM signal from the speed controller. For this purpose, the change in tin and / or tout from one period of the PWM signal to the next can be examined. Analyzing gradients / transients derived from the PWM signal can eliminate signal fluctuations caused by disturbances and thus reduce the susceptibility to errors of the method proposed here.

[0025] According to an advantageous embodiment, a time period can be used to detect an irregular ignition process. This period extends from the change in the control signal indicated by the ignition process (activation of the igniter) until the control signal returns to its pre-ignition value (due to the speed control) within a defined tolerance range. In other words, the control signal can be used to determine the time the speed controller needs to compensate for a change in the blower speed caused by the ignition process (and the associated pressure pulse) and to restore the blower speed to its pre-ignition level. The tolerance range serves to compensate for minor shifts in the control signal caused by disturbances (e.g., temperature fluctuations).

[0026] The duration can be a measure of the intensity of the pressure pulse triggered by the ignition process, which can increase with its intensity.

[0027] According to an advantageous embodiment, the duration can range from 1 to 3 seconds. The duration can also depend on various characteristics and conditions, whereby the duration for a regular ignition process is easily determined and is often less than 1 second, thus allowing for a simple distinction between a regular and an irregular ignition process. The programming and settings of the controller, as well as the characteristics of the specific heating device, should also be considered in this analysis.

[0028] According to one embodiment, both the change in the PWM signal and the time interval between the change in the control signal triggered by the ignition process (ignition activation) and the return of the control signal to its pre-ignition value (due to speed control) within a defined tolerance range can be used. This advantageously enables the detection of component defects. For example, if the control signal cannot be returned to the predetermined output value (within a tolerance range) within a certain time, this could indicate a defect in the blower and / or the exhaust system (exhaust duct, exhaust system). This defect could have been caused by a (temporally) delayed ignition.

[0029] According to an advantageous embodiment, the PWM signal can only be detected and evaluated for as long as the ignition process lasts, for example characterized by an activated ignition device.

[0030] According to a further advantageous embodiment, an irregular ignition process can be detected by an overshoot of the controller's control signal. The controller's programming and the characteristics of the specific heating device should also be taken into account.

[0031] According to an advantageous embodiment, a signal can be determined and used for an ignition process during the evaluation of the control signal. This signal results from a combination (by means of one or more arithmetic operations) of the aforementioned signals derived from the control signal (the control signal itself, at least one gradient derived from the control signal, and / or a specific time period (until the control signal returns to its value before the ignition process)). Advantageously, this allows inaccuracies, for example, caused by disturbances (or reactions of the speed control to disturbances), to be compensated for, and particularly reliable detection of irregular ignition (hard ignition, lack of flame formation) to be achieved.

[0032] According to an advantageous embodiment, if or after an irregular ignition process is detected, the speed control can automatically adjust the fan speed via the control signal so that it is (re)brought back into a predefined range. In particular, it is possible to automatically restore suitable delivery conditions for ignition immediately after the irregular ignition process is detected. In this way, a shutdown of the heating unit can (initially) be avoided, or an attempt can be made to stabilize the process. The effect of the fan speed adjustment can be further monitored via the control signal, for example, over a predefined adjustment period. After the adjustment period has elapsed, the system can then either return to normal operation or switch to emergency operation or an emergency stop.

[0033] According to an advantageous embodiment, after the detection of an irregular ignition process, particularly after the automatic readjustment described above, the heater can be (automatically) shut down and / or, in particular, restarting it (also automatically) can be prevented (blocked). Restarting it can only be performed by a specialist workshop or a qualified person. This advantageously prevents damage to the heater.

[0034] According to an advantageous embodiment, information about the detection of an irregular ignition process can be displayed via a display device on the heating appliance and / or made available for retrieval via a network, in particular the internet, and / or sent as a message. For example, the information can thus be made available to a specialist company and / or a user / operator of the heating appliance on a mobile device or a computer. A specialist company could then (automatically and independently) schedule and carry out a maintenance appointment.

[0035] Another aspect is the proposal for a computer program designed to (at least partially) execute the procedure presented here. In other words, this specifically concerns a computer program (product) comprising instructions that, when executed by a computer, cause it to carry out the procedure described here.

[0036] Another aspect that is proposed is a machine-readable storage medium on which the computer program is stored.

[0037] The machine-readable storage medium is usually a computer-readable data carrier.

[0038] Another aspect is the proposal for a control unit for a heating appliance, designed to carry out the procedure presented here. This control unit may, for example, include or be equipped with a processor. In this context, the processor can, for instance, execute the procedure stored in the control unit's memory. Advantageously, a control unit often already regulates the power of the conveying device or the blower, so that a parameter to be acquired according to the proposed procedure is already available to the control unit. Furthermore, a speed control for adjusting the blower speed may be provided, which may be part of the control unit or at least controllable by it.

[0039] Another aspect being considered is the proposal for a heating appliance with a control unit as presented here. This heating appliance is specifically a gas-fired unit with a gas burner and a delivery system comprising a blower that can supply a mixture of fuel gas and combustion air to the gas burner. A speed control for adjusting the blower speed may be provided, which may be part of the control unit or at least controllable by it.

[0040] The details, features, and advantageous configurations discussed in connection with the process may also occur in the computer program, control unit, heating device, and / or application presented here, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0041] This document describes a method for commissioning a heating appliance, a computer program, a control and monitoring device, and a heating appliance itself, which at least partially solve the problems described with reference to the state of the art. In particular, the method for commissioning a heating appliance, the computer program, the control and monitoring device, and the heating appliance contribute to enabling the automated detection of irregular start-up processes and preventing subsequent restarts and their potential negative consequences.

[0042] Furthermore, the invention can be implemented with a heating device according to the prior art without any structural modifications and can therefore also be easily retrofitted to existing devices in the form of a software update.

[0043] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a heating device proposed here, and Fig. 2: signal waveforms that can occur when carrying out a method proposed here.

[0044] Fig. 1 Figure 1 shows an exemplary and schematic representation of a heating appliance 1 proposed here. A blower 2, acting as a conveying device, can be configured to draw in a mass flow of combustion air via a combustion air supply 4, to which fuel gas can be added via a gas valve 5. The mixture of combustion air and fuel gas can be supplied to a burner 3 of the heating appliance 1 via a mixture channel 16. The combustion products can be discharged via an exhaust gas channel 8 and an exhaust system 9.

[0045] The heating unit 1 can include a control unit 7, which may have a speed controller 6 for adjusting the speed 11 of the blower 2. The control unit 7 can be electrically connected to the blower 2 and the gas valve 5. A display device 18 can show information about the result of a procedure proposed herein and, in particular, indicate whether the heating unit 1 is switched off or blocked. The control unit 7 can also be connected to a network 17, via which information about an (automatically) detected irregular ignition process can be made available for retrieval or sent as a message.

[0046] Fig. 2 This shows signal waveforms that can occur when carrying out a procedure presented here. In the Fig. 2The diagram shows a control signal 10 of the speed control 6 and a speed 11 of the fan 2 as a function of time t, specified in seconds. The control signal 10 of the speed control 6 can be a PWM (pulse-width modulated) signal, given as a percentage [%] of the rated power of the fan 2, and the speed 11 of the fan 2 can be given in rpm [revolutions per minute].

[0047] When the heating unit 1 is put into operation, the speed 11 of the blower 2 can be increased to a target speed 12. For this purpose, the speed control 6 can adjust the control signal 10 accordingly. After reaching the target speed 12, fuel gas can be added to the delivered mass flow of combustion air via the gas valve 5. Ignition 13 can then be initiated via an igniter.

[0048] The ignition 13 causes the speed 11 of the blower 2 to decrease due to a triggered pressure pulse, which the speed control 6 immediately and automatically counteracts by adjusting (here increasing) the control signal 10. After a time period 15, the target speed 12 can be reached again 14.

[0049] An irregular ignition process can be detected based on the time duration 15 and / or by a quantitative consideration of the change (increase) of the control signal 10 of the speed control 6.

[0050] By providing information about a detected irregular ignition process (even after readjustment) via the display device 18 and / or via a network 17 for retrieval and / or by sending a notification, a specialist company can automatically and independently schedule and carry out a maintenance appointment. Reference symbol list

[0051] 1 Heater 2 Blower 3 Burner 4 Combustion air supply 5 Gas valve 6 Speed ​​control 7 Control unit 8 Exhaust duct 9 Exhaust system 10 Control signal 11 Speed ​​12 Target speed 13 Ignition 14 Re-establishment 15 Duration 16 Mixture channel 17 Network 18 Display device

Claims

1. Method for detecting an irregular ignition process of a heating appliance (1), comprising a fan (2) and a speed control (6) for setting the speed (11) of the fan (2), which is designed to convey a mass flow of a mixture of a fuel and combustion air to a burner (3) of the heating appliance (1), wherein during the ignition process a pulse width modulated signal is detected as a control signal (10) for the speed control (6) and an irregular ignition process is detected by evaluating the control signal (10), namely by observing the control signal (10) and its change over time.

2. Method according to claim 1, wherein the speed control (6) comprises a controller which is a PI controller.

3. Method according to one of the preceding claims, wherein an irregular ignition process is concluded in the event of a sudden change in the control signal (10) of more than 10%.

4. Method according to one of the preceding claims, wherein a time period (15) is used to detect an irregular ignition process, from a change in the control signal (10) indicated by the ignition process until the control signal (10) returns to the value before the ignition process within a defined tolerance range.

5. Method according to claim 4, wherein the time period (15) is greater than 1 second.

6. Method according to one of the preceding claims, wherein, upon detection of an irregular ignition process, the speed control (6) automatically adjusts the speed (11) of the fan (2) to a predetermined range by means of the control signal (10).

7. Method according to one of the preceding claims, wherein, upon detection of an irregular ignition process, the heating appliance (1) is taken out of operation.

8. Method according to one of the preceding claims, wherein, upon detection of an irregular ignition process, information thereon is displayed via a display device (18) and / or made available for retrieval via a network (17) and / or sent as a message via the network (17).

9. Control and regulating device (7) for a heating appliance (1), designed to cause the heating appliance (1) to carry out a method according to one of claims 1 to 8.

10. Heating appliance (1) comprising a fan (2) with a speed control (6) and a control and regulating device (7) according to claim 9.

11. Computer program comprising instructions which cause a heating appliance (1) according to claim 10 to carry out a method according to one of claims 1 to 8.

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