EP3869102A1 - Method and device for diagnosing faults affecting a firing controller - Google Patents

Abstract

The invention relates to a method for testing the connection (4) of an ignition module (10) on an automatic furnace (1), the ignition module (10) being designed to generate a high voltage with the aid of a capacitor (11) that can be charged by a power supply (2) , wherein the ignition module (10) can be connected to an ignition electrode (12) in a combustion chamber (9) of a combustion system (8) and the time course of a voltage (U) that builds up when the power supply (2) is switched on is monitored continuously or at time intervals and from this the quality of the connection (4) of the ignition module (10) is inferred. A device according to the invention has an ignition module (10) and a power supply (2) which are connected via an electrical supply line (3) and are arranged in or on an automatic firing device (1), a voltage measuring device (5) being available for voltage measurement in the supply line (3) and with evaluation electronics (6) which can diagnose the state of the electrical supply line (3) or possible errors in the overall system from measured voltage values and / or their temporal progression. According to the invention, a diagnosis can be made with little effort as to whether the ignition module (10) is correctly connected or which error is present in the connection.

Description

The invention is in the field of automatic firing systems for firing systems in which a mixture of combustion air and liquid or gaseous fuel is burned, in particular it relates to an automatic gas firing system for a burner in a heater for hot water preparation or heating of a building.

A burner control regulates and monitors the operation of a combustion system that is operated with gaseous or liquid fuel. Modern automatic firing systems contain central electronics to which various sensors are connected, whose measurement signals are processed and evaluated. The electronics also control or regulate valves for the intake of combustion air and fuel and ensure that the combustion is ignited by an ignition device.

In addition, the presence of a flame and the ratio of air to fuel are monitored in order to ensure the most environmentally friendly combustion possible. Other parameters, such as B. Temperatures at different points can also be monitored. In the event of a malfunction, the automatic firing system ensures a safe shutdown in all operating situations, in particular a shutdown of the fuel supply, and ensures that the firing system cannot be easily switched on again even after a power failure. However, since there can be many causes for a malfunction and shutdown, it is desirable to be able to diagnose a possible error as easily as possible during a subsequent check.

Each burner control unit is also assigned a more or less separately designed ignition module, which is used to generate an ignition spark, which in turn starts the combustion of the fuel-air mixture that has been admitted. The ignition module requires power from the burner control unit from a power supply and is therefore connected to it via a power supply line. It is still connected to an ignition electrode in the combustion system via a high-voltage line and is z. B. controlled via a signal line. The reason for a malfunction in the combustion system can therefore also be a fault in the ignition module or its cabling. If it is a plugged-on module with electrical plug connections, this connection may, for example, have loosened so that an ignition spark could no longer be generated.

Automatic burner control units have been known for a very long time and, for example, in the DE 24 26 943 B2 or the EP 2 295 863 B1 described. Such devices are equipped with numerous safety devices to ensure safe operation for users and the environment. So it comes with occasional malfunctions, z. If a deliberate ignition does not take place, to a shutdown, but it can be difficult to diagnose the exact cause of the malfunction.

The present invention aims to provide a remedy here in order to enable a method that can be carried out quickly with little additional outlay on equipment, at least for checking the devices required for ignition or their connection.

A method according to claim 1, a device according to claim 7 and a computer program product according to claim 10 contribute to achieving these objects. Advantageous refinements and developments of the invention are specified in the respective dependent claims.

The method relates to the testing of the connection of an ignition module to an automatic firing system, the ignition module being designed to generate a high voltage with the aid of at least one capacitor that can be charged by a power supply, the ignition module being connectable to an ignition electrode in a combustion chamber of a combustion system, and the time profile a voltage that builds up when the power supply is switched on is observed continuously or at time intervals and the quality of the connection of the ignition module is deduced from this.

The power supply is preferably designed in such a way that it supplies a predeterminable voltage and its power is limited to a predeterminable value. By limiting the power, only a limited current flows to the capacitor, so that a voltage that can be measured builds up there over a certain period of time after the power supply is switched on. It makes sense to measure this voltage in the automatic furnace close to the power supply before the first plug-in or soldered connections.

The power supply and the ignition module can be arranged in or on the automatic firing unit and connected by an electrical lead, the course of the voltage in the lead being observed after the power supply has been switched on and conclusions about the integrity of the arrangement or errors therein. The supply line can have different lengths depending on the spatial arrangement of the ignition module. A correctly connected, functional ignition module always leads to a characteristic voltage curve after switching on, so that deviations from this curve can provide an initial indication of possible errors.

In particular, if the voltage rises too quickly compared to empirical values, this indicates a connected supply line without an ignition module. The capacity the supply line alone also leads to an increase in voltage, but this capacitance is so small that the increase occurs very quickly. This can easily be detected and converted into a corresponding error diagnosis.

Conversely, an increase in voltage that is too low compared to empirical values indicates a completely missing or faulty supply line. Practically no tension then builds up.

In order to keep the technical effort low when implementing the invention, the exact course of the voltage curve does not necessarily have to be recorded. It is enough z. For example, if the voltage is measured 3 to 10 times after switching on the power supply at predefinable time intervals of 10 to 100 ms [milliseconds] and the measured values or a time curve of the voltage interpolated from the measured values are used for a diagnosis. The comparison of two successive measured values already provides information about the time course of the voltage, so that the desired information can be obtained with just a few measured values. With preferably five measured values, a reliable statement can be made as to whether the course over time corresponds to empirical values or deviates therefrom upwards or downwards. In this way, the ignition module can be excluded or identified as the cause of the error, with a diagnosis of the possible cause of the error (loosened supply line, no ignition module connected, etc.) being possible. The time intervals between individual measurements and their number can be adapted to the properties of each system and deliver redundant, robust measurement results that are hardly influenced by malfunctions or inaccuracies in operation. In addition, information about the state of the ignition module, in particular about the charging curve of the capacitor, can be obtained from the measured values even if there is no disturbance.

A device, in particular provided or set up for carrying out the described method, has an ignition module and a power supply, which are connected via an electrical supply line and are arranged in or on a burner control unit, a voltage measuring device being present for a voltage measurement in the supply line and a Evaluation electronics are present that can diagnose the state of the electrical supply line and possible errors in the system from measured voltage values and / or their temporal progression.

Since every modern automatic burner control has electronic components and generally a microprocessor or controller anyway, it is advantageous to integrate the evaluation electronics into the control electronics of the automatic burner control unit. Their microprocessor can, in addition to its other functions (it controls the ignition module in any case if required), also process the measured voltage values according to the invention and evaluate them with its other diagnostic functions.

The voltage measuring device is preferably arranged at the output of a power source of limited power in the automatic furnace. In normal operation, it measures the course of the voltage of the capacitor over time, but in the event of faults on the capacitor or the supply line (including contacts) it can still carry out voltage measurements and determine deviations from the normal course.

A computer program product is also specified, comprising commands that cause the described device to carry out the proposed method. Modern burners typically contain an electronic control which contains at least one programmable microprocessor which can be controlled by such a computer program product (in particular also as part of a more comprehensive computer program product for the entire control of the automatic firing system).

Fig. 1:

schematisch eine erfindungsgemäße Vorrichtung, und

Fig. 2:

ein Diagramm zur Veranschaulichung des zeitlichen Verlaufs einer erfindungsgemäß gemessenen Spannung im Normalbetrieb und bei Störungen.

A schematic embodiment of the invention, to which it is not limited, and the mode of operation of the method according to the invention will now be explained in detail with reference to the drawing. They represent:

Fig. 1:

schematically a device according to the invention, and

Fig. 2:

a diagram to illustrate the time course of a voltage measured according to the invention in normal operation and in the event of malfunctions.

Figure 1 shows schematically an embodiment of a device according to the invention, namely an automatic furnace 1 for a furnace 8. The automatic furnace 1 is typically connected via signal lines 14 to some sensors, not shown here, which provide information about the state of the furnace 8. It also has control electronics 7 in a manner known per se, which controls actuators (also not shown) via control lines 15 on the combustion system 8 in order to set the desired parameters for the operation of the combustion system 8 and to switch the system on or off as required. The present invention deals with a component likewise typically assigned to an automatic firing device 1, namely a so-called ignition module 10. This is used to generate an ignition spark by means of an ignition electrode 12 in a combustion chamber 9 of the furnace 8. The ignition voltage is transmitted to the ignition electrode 12 via a high-voltage line 13 . The ignition module 10 is supplied with energy from a power supply 2 in the automatic furnace via a supply line 3 connected to a connection 4. The ignition module 10 contains a capacitor 11 which is charged for ignition and then discharges to generate an ignition spark, for example via an ignition transformer (not shown). According to the invention, the capacitor 11 is charged in a defined manner by the power supply 2. For this purpose, the power supply 2, which is designed in principle to supply a constant, predeterminable voltage, has its output limited (e.g. provided with a suitable internal resistance). This means that the voltage rise on the connected capacitor 11 takes place in a defined manner after switching on. According to the invention, this can be used to check the functionality of the ignition module 10, at least with regard to the correct connection 4 of the ignition module 10 . Connectors), arranged, which measures the temporal course of the voltage quasi continuously or the respective voltage at time intervals. The measured voltages are fed to evaluation electronics 6, which can also be part of control electronics 7, and are compared there with empirical values (calibration data). If the measured voltage rises too quickly but to a high value, it can be concluded from this that although a supply line 3 is connected, it is not correctly connected to a functioning capacitor 11. If the voltage increases quickly, but only to a low value, it can be concluded that no supply line is connected. The capacitance of the capacitor 11, that is to say its functionality, can also be inferred from more precise observations of the voltage profile. When the combustion system 8 is shut down, this information is available and can thus be taken into account when diagnosing the reason for the shutdown. The information can be made visible via a display device 16 (for example a display or signal lights).

Fig. 2 shows a schematic diagram to illustrate various voltage curves on the supply line 3 to the capacitor 11. The normal curve A shows the time curve of the voltage U within a predefinable evaluation period (e.g. 0.25 s) after switching on the power supply 2 at time t0 if the ignition module 10 is correctly connected. If the capacitor is not connected, curve B results without a capacitor. If no feed line 3 is connected either, the result is curve C without a connected line. A simplified measurement method which is used for the practice can be used robustly, measures z. B. at 5 times t1, t2, t3, t4, t5 at an interval of about 50 ms each, the voltage on the supply line 3. The first measurement takes place 50 ms after a defined switching on of the power supply 2, which only takes place when the measured voltage Is zero. Then, the voltages measured at intervals are evaluated as follows. Each measured voltage value must exceed a defined positive difference (based on empirical values) to the previous measured value. The last measured value must not exceed a defined maximum value. If the ignition module is correctly connected, these conditions are met. If only the supply line 3 is connected, but no ignition module 10, the voltage rises very quickly up to the first measurement time, but the minimum increases for the following measurement points are not observed. If neither supply line 3 nor ignition module 10 are connected, the voltage increases only slightly and very quickly reaches a low end value. The increases in voltage in the later measured values are not met.

According to the invention, a diagnosis can be made with little effort as to whether the ignition module is correctly connected or which error is present in the connection.

List of reference symbols

1

Burner control

2

Power supply

3

Supply line

4th

connection

5

Voltage measuring device

6th

Evaluation electronics

7th

Control electronics

8th

Combustion system

9

Combustion chamber

10

Ignition module

11

capacitor

12th

Ignition electrode

13th

High voltage line

14th

Signal lines

15th

Control lines

16

Display device

t

Time [ms]

U

Voltage [V]

A.

Normal course

B.

Course without capacitor

C.

Course without a connected line

Claims (10)

Method for testing the connection (4) of an ignition module (10) on an automatic firing unit (1), the ignition module (10) being designed to generate a high voltage with the aid of a capacitor (11) that can be charged by a power supply (2), the ignition module (10) can be connected to an ignition electrode (12) in a combustion chamber (9) of a combustion system (8) and the time course of a voltage (U) that builds up when the power supply (2) is switched on is monitored continuously or at time intervals and is then applied to the Quality of the connection (4) of the ignition module (10) is closed. Method according to claim 1, wherein the power supply (2) supplies a predeterminable voltage and its power is limited to a predeterminable value. Method according to claim 1 or 2, wherein the power supply (2) and the ignition module (10) are arranged in or on the automatic furnace (1) and are connected by an electrical supply line (3) and wherein the course of the voltage in the supply line (3) follows Switching on the power supply (2) is observed and the integrity of the arrangement or errors in it can be deduced from its course. Method according to one of the preceding claims, wherein an excessively rapid or excessively high rise in the voltage (U) compared to empirical values indicates a connected supply line (3) without an ignition module (10). Method according to one of the preceding claims, wherein an increase in the voltage (U) that is too small compared to empirical values indicates a missing or faulty supply line (3). Method according to one of the preceding claims, wherein the voltage (U) is measured 3 to 10 times after switching on the power supply (2) at predeterminable time intervals of 10 to 100 ms [milliseconds] and the measured values or a time curve interpolated from the measured values the voltage (U) can be used for a diagnosis. Device, in particular for carrying out the method according to one of the preceding claims, wherein an ignition module (10) and a power supply (2), which are connected via an electrical supply line (3), are arranged in or on an automatic furnace (1), wherein a Voltage measuring device (5) is available for voltage measurement in the supply line (3) and with evaluation electronics (6) which can diagnose the state of the electrical supply line (3) or possible errors in the overall system from measured voltage values and / or their temporal progression . Apparatus according to Claim 7, the evaluation electronics (6) being integrated into control electronics (7) of the automatic furnace (1). Device according to one of Claims 7 or 8, the voltage measuring device (5) being arranged at the output of a current source (2) of limited power in the automatic furnace (1). Computer program product, comprising instructions that cause an apparatus according to any one of claims 7 to 9 to carry out a method according to any one of claims 1 to 6.

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