EP0279771A1 - Method for regulating the flow of combustion air in a fuel-heated heat source - Google Patents

Method for regulating the flow of combustion air in a fuel-heated heat source Download PDF

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Publication number
EP0279771A1
EP0279771A1 EP88730029A EP88730029A EP0279771A1 EP 0279771 A1 EP0279771 A1 EP 0279771A1 EP 88730029 A EP88730029 A EP 88730029A EP 88730029 A EP88730029 A EP 88730029A EP 0279771 A1 EP0279771 A1 EP 0279771A1
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EP
European Patent Office
Prior art keywords
line
speed
gas
value
fan
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Application number
EP88730029A
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German (de)
French (fr)
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EP0279771B1 (en
Inventor
Winfried Dr. Hangauer
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N.V. VAILLANT S.A.
Vaillant Austria GmbH
Vaillant GmbH
Vaillant SARL
Vaillant Ltd
Original Assignee
Vaillant Austria GmbH
Nv Vaillant Sa
Joh Vaillant GmbH and Co
Vaillant GmbH
Vaillant SARL
Vaillant Ltd
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Publication of EP0279771A1 publication Critical patent/EP0279771A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/04—Regulating fuel supply conjointly with air supply and with draught
    • F23N1/042—Regulating fuel supply conjointly with air supply and with draught using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/18—Measuring temperature feedwater temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2233/00—Ventilators
    • F23N2233/02—Ventilators in stacks
    • F23N2233/04—Ventilators in stacks with variable speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/16—Fuel valves variable flow or proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • the present invention relates to a method for controlling the combustion air flow rate of a fuel-heated heat source.
  • a fuel-heated heat source is understood to mean any gas or oil-heated device, be it an oven, water heater or circulating water heater for heating and process water preparation.
  • the present invention is based on the object of specifying a method for regulating the combustion air throughput, in which it is no longer necessary to separately adapt the pipes and tube guides for the fresh air supply / exhaust gas discharge and in which a stable behavior of the combustion air throughput is established, regardless of this whether it is a device with air-side and gas-side modulation or only air-side modulation.
  • the advantage of this solution lies in the independent adaptation of the combustion air throughput to the device-typical resistances in the air and exhaust gas path due to the installation location. There is always an optimal size of the air throughput with regard to the efficiency, since the air throughput is always a certain, but definable threshold above the switch-off criterion, that is, the unsanitary combustion.
  • a circulating water heater 1 has a housing 2, which in its interior 3 forms a combustion chamber which is shielded from the top by a further inner housing 4.
  • the interior 3 is penetrated by a heat exchanger 5, which is connected to a return line 6 and to a flow line 7, in which a flow temperature sensor 8 is arranged, which is connected via a line 9 to a controller 10.
  • the flow line 7 is provided with a circulation pump 11, the drive motor 12 of which is supplied with operating voltage from the controller 10 via a line 13.
  • the flow line 7 leads downstream of the pump 11 to a heating system 14, which consists of a plurality of radiators, underfloor heating sections or a domestic hot water tank connected in series and / or in parallel, to which the return line 6 is connected on the return side.
  • the heat exchanger 5 is heated by a gas burner 15, which is fed from a gas line 16, in which a shut-off valve 17 is arranged, the electromagnet 18 of which is fed by a control line 19 which originates from the controller 10.
  • a proportional control valve 20 the electromagnet 21 of which is equally connected to the controller 10 via a control line 22.
  • the inner housing 4 merges into an exhaust gas line 23, in which a fan 24 is arranged, the associated motor of which is supplied from an actuating line 25 with operating voltage is opened, which comes from a speed controller 26.
  • a speed actual value transmitter 27 is assigned to the fan and is connected to the speed controller 26 via a measuring line 28.
  • a speed setpoint value is fed to the speed controller via a line 29 which starts from the controller 10.
  • a target value transmitter 30 is connected to the controller 10, with which a target value for the flow temperature of the heating system can be specified.
  • the outer housing 2 is connected to an outer tube 31, which extends concentrically and at a distance 32 from the exhaust pipe 23, which forms the inner tube.
  • the length of the concentric double pipe 31/23 from the installation location of the fan directly in the device to a breakthrough through a boundary wall 33 of the installation space is almost as long as possible, but in practice is limited to a range of three to five meters.
  • the double tube passes through the wall and ends in a head 34 in the outside atmosphere.
  • An anemometer sensor 35 is assigned to the supply air path and reports a continuous signal for the air throughput to an anemometer 37 via a line 36.
  • a further input of the anemometer is formed by line 22, and output signals of the anemometer are sent to controller 10 via line 38, here an enable signal, and via line 39, here a correction signal.
  • the device in the controller 10 has a temperature controller.
  • the actual value of the flow temperature is detected by sensor 8 and reported to controller 10 via line 9.
  • a comparison is made with the temperature target value specified on the target value transmitter 30, and the device is put into operation in the event of a control deviation.
  • the magnet 18 is first excited so that the gas valve 17 opens fully.
  • a more or less large control signal results on line 22, so that the magnet 21 is subjected to partial load or full load values, so that the valve 20 opens more or less.
  • a setpoint value for a suitable air throughput is given to the anemometer 37 via line 22.
  • the speed controller 26 is first activated via the line 29, so that the fan 24 first starts at the maximum speed and is then reduced to a value which is suitable for the expected gas throughput.
  • the speed of the fan is then regulated in control loop 27, 28, 26, 25 at this speed.
  • the combustion air flow rate which arises due to the fan working is generated from the atmosphere via the head 34 promotes and penetrates the supply air path, which corresponds to the distance 32 outside the device.
  • the supply air path is the distance between the two housings 2 and 4 in which the anemometer sensor 35 is arranged.
  • the air flow rate which arises is measured as an actual value by the latter and is fed via line 36 to the anemometer.
  • a target-actual comparison takes place here, and if a minimum throughput matching the expected gas throughput is exceeded, the controller 10 is released via the line 38, so that the two gas valves 17 and 20 can now open accordingly.
  • the gas emerging from the burner 15 is ignited, the burner burns and heats the heat exchanger 5, and the flow temperature rises. If the actual air throughput falls below the minimum threshold which is variable depending on the gas throughput, the controller is blocked via line 38, so that both gas valves close.
  • the relationship between the target value for the speed controller on line 29 and the actual value of the gas throughput, corresponding to a certain voltage on line 22, is fixed. However, the relationship between the air flow rate and the actual value of the fan speed is by no means fixed. The relationship between the actual value of the gas throughput and the switch-off threshold for the anemometer is also fixed.
  • the voltage USMV for the degree of opening of the gas solenoid valve is plotted in the abscissa, the values for the gas throughput Q and for the desired or actual value of the speed of the fan are plotted in the ordinate.
  • the sloping part of the curves means the modulation range, the horizontal part the full load state. The zero point shift comes about because one wants to suppress working of the device below a certain partial load range.
  • FIG. Three additionally shows the curves for the voltage of the anemometer (UA) and the voltage of the switch-off threshold (US).
  • the curve US defines the switch-off threshold.
  • the curve US is laid out in such a way that, taking into account the properties typical of the device, it is still hygienically perfect Allows combustion. Falling below this threshold therefore results in unsanitary combustion and must therefore be avoided in any case.
  • the voltage UA is an internal voltage in the anemometer 37, it is variable with the signal from the anemometer sensor 35. If the curves US and UA coincide, this means that the combustion is just hygienic.
  • a widening of the curves of the US and UA means an operation with an efficiency that gets worse the further the curves are apart.
  • curve UA depends on the actual air flow. This is influenced by the fan speed and by changes in the entire air exhaust system of the heat source, for example also by pollution.
  • the aim now is to set the value of UA as close as possible to the value of US, but without reaching or falling below the value for US.
  • the anemometer 37 has a difference generator and forms the difference between the actual value of the air throughput, given by the sensor 35, expressed by UA and the value of the switch-off threshold US.
  • This difference is dependent on the load on the device, that is to say on the open state of the solenoid valve 20/21, that is to say on the signals prevailing on the line 22.
  • the difference is compared with a target value, which in the Anemometer 37 can be predetermined.
  • the target value can be constant, but can also be variable via the load on the device. If the value of this difference falls below a predeterminable size, the speed of the fan motor is increased and if it falls below this, the target value for the speed controller 26 is tracked via the line 39 and the controller 10. This variation of the speed then leads to a shift of the curve UA in the direction of correction.
  • the difference is defined by the distance 50.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)

Abstract

Method for regulating the fuel air flow for a gas-fired water heater, with a fan, the drive motor of which is of variable speed, a constant actual-value indicator for the air flow and with a device for switching off the gas supply in the event of the air flow falling below a minimum, the difference (50) being formed according to the invention between the actual value (35) of the air flow and a switch- off threshold (US), and the speed of the fan motor (24) being increased when the difference falls below and reduced when it exceeds a presettable value. <IMAGE>

Description

Die vorliegende Erfindung bezieht sich auf ein Verfahren zum Regeln des Verbrennungsluftdurchsatzes einer brenn­stoffbeheizten Wärmequelle.The present invention relates to a method for controlling the combustion air flow rate of a fuel-heated heat source.

Unter brennstoffbeheizter Wärmequelle ist hier jedwedes gas- oder mit Öl beheizte Gerät zu verstehen, sei es Ofen, Wassererhitzer oder Umlaufwasserheizer für Heizung und Gebrauchswasserbereitung.A fuel-heated heat source is understood to mean any gas or oil-heated device, be it an oven, water heater or circulating water heater for heating and process water preparation.

Es sind sogenannte kaminlose Umlaufwasserheizer auf dem Markt, die zur Unterstützung der Verbrennung mit einem Abgasventilator arbeiten, dessen Antriebsmotor drehzahl­variabel ausgeführt ist. Da der Einbauort der Umlaufwas­serheizer häufig nicht bekannt ist, wird der maximale Brennstoffdurchsatz und der maximale Luftdurchsatz nach der größtmöglichen Länge der Zuluft-/Abgasabführung be­messen. In der Praxis werden solche Rohrlängen als kon­ zentrische Rohre mit Längen von maximal fünf Meter gefertigt. Es tritt aber nun häufig der Fall auf, daß der Mauerdurchbruch zum Anschluß des Gerätes weit näher als in dieser Entfernung zu liegen kommt. Um für diesen Fall günstige Verbrennungsverhältnisse zu schaffen, werden Blenden in die Rohre eingeführt, um künstliche Luftwider­stände zu bilden. Es liegt auf der Hand, daß das Anpassen dieser Blenden viel Fingerspitzengefühl vom Fachmann be­nötigt und daß in der Praxis mit Fehlanpassungen zu rech­nen ist. Hierbei sind Fehlanpassungen in Richtung auf unhygienische Verbrennung und schlechten Wirkungsgrad möglich. Eine geräteinterne Sicherung verhindert aller­dings die unhygienische Verbrennung. In der Praxis laufen solche Geräte aber häufig mit einem zu geringen Wirkungs­grad, weil zuviel Luft dem Gerät zugeführt wird.There are so-called chimney-free circulating water heaters on the market that work with a flue gas fan to support combustion, the drive motor of which is variable in speed. Since the installation location of the circulating water heaters is often not known, the maximum fuel throughput and the maximum air throughput are measured according to the greatest possible length of the supply air / exhaust gas discharge. In practice, such pipe lengths are con centric pipes with a maximum length of five meters. But now it often happens that the wall opening for connecting the device comes much closer than this distance. In order to create favorable combustion conditions for this case, screens are inserted into the pipes to create artificial air resistances. It is obvious that the adjustment of these screens requires a lot of tact from the expert and that in practice mismatches can be expected. Mismatches in the direction of unsanitary combustion and poor efficiency are possible. An internal fuse prevents the unsanitary combustion. In practice, however, such devices often run with too little efficiency because too much air is supplied to the device.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren zum Regeln des Verbrennungsluftdurchsatzes anzugeben, bei dem es nicht mehr notwendig ist, die Rohre und Rohrführungen für die Frischluftzufuhr/Abgasabfuhr gesondert anzupassen und bei dem sich ein stabiles Ver­halten des Verbrennungsluftdurchsatzes einstellt, und zwar unabhängig davon, ob es sich um ein Gerät mit luft- ­und gasseitiger Modulation oder nur luftseitiger Modula­tion handelt.The present invention is based on the object of specifying a method for regulating the combustion air throughput, in which it is no longer necessary to separately adapt the pipes and tube guides for the fresh air supply / exhaust gas discharge and in which a stable behavior of the combustion air throughput is established, regardless of this whether it is a device with air-side and gas-side modulation or only air-side modulation.

Die Lösung der Aufgabe liegt erfindungsgemäß in den kenn­zeichnenden Merkmalen des Patentanspruchs.The object is achieved according to the invention in the characterizing features of the patent claim.

Der Vorteil dieser Lösung liegt in der selbständigen An­passung des Verbrennungsluftdurchsatzes an die geräte­typischen und durch den Einbauort herrschenden Widerstän­de im Luft- und Abgasweg. Es stellt sich immer eine optimale Größe des Luftdurchsatzes hinsichtlich des Wirkungsgrades ein, da der Luftdurchsatz immer um eine bestimmte, aber vorgebbare Schwelle über dem Abschalt­kriterium, das heißt der unhygienischen Verbrennung, liegt.The advantage of this solution lies in the independent adaptation of the combustion air throughput to the device-typical resistances in the air and exhaust gas path due to the installation location. There is always an optimal size of the air throughput with regard to the efficiency, since the air throughput is always a certain, but definable threshold above the switch-off criterion, that is, the unsanitary combustion.

Weitere Ausgestaltungen und besonders vorteilhafte Wei­terbildungen der Erfindung gehen aus der nachfolgenden Beschreibung hervor, die ein Ausführungsbeispiel der Er­findung zum Inhalt hat.Further refinements and particularly advantageous developments of the invention can be found in the following description, which contains an exemplary embodiment of the invention.

Es zeigen:

  • Figur eins ein Prinzipaufbaubild eines Umlaufwasserhei­zers und
  • die Figuren zwei und drei Diagramme.
Show it:
  • Figure one is a schematic diagram of a water heater and
  • the figures two and three diagrams.

In den drei Figuren bedeuten gleiche Bezugszeichen jeweils die gleichen Einzelheiten.In the three figures, the same reference symbols each denote the same details.

Ein Umlaufwasserheizer 1 weist ein Gehäuse 2 auf, das in seinem Innenraum 3 eine Brennkammer bildet, die von einem weiteren Innengehäuse 4 nach oben abgeschirmt ist. Der Innenraum 3 wird durch einen Wärmetauscher 5 durchsetzt, der an eine Rücklaufleitung 6 und an eine Vorlaufleitung 7 angeschlossen ist, in der ein Vorlauftemperaturfühler 8 angeordnet ist, der über eine Leitung 9 mit einem Regler 10 verbunden ist.A circulating water heater 1 has a housing 2, which in its interior 3 forms a combustion chamber which is shielded from the top by a further inner housing 4. The interior 3 is penetrated by a heat exchanger 5, which is connected to a return line 6 and to a flow line 7, in which a flow temperature sensor 8 is arranged, which is connected via a line 9 to a controller 10.

Die Vorlaufleitung 7 ist mit einer Umwälzpumpe 11 ver­sehen, deren Antriebsmotor 12 über eine Stelleitung 13 vom Regler 10 mit Betriebsspannung versorgt wird. Die Vorlaufleitung 7 führt stromab der Pumpe 11 zu einer Hei­zungsanlage 14, die aus einer Vielzahl in Serie und/oder parallel geschalteten Radiatoren, Fußbodenheizungsab­schnitten oder einem Brauchwasserspeicher besteht, an den rücklaufseitig die Rücklaufleitung 6 angeschlossen ist. Der Wärmetauscher 5 ist von einem Gasbrenner 15 beheizt, der aus einer Gasleitung 16 gespeist ist, in der ein Schließventil 17 angeordnet ist, dessen Elektromagnet 18 von einer Stelleitung 19 gespeist ist, die vom Regler 10 ausgeht. In der Gasleitung 16 liegt ein Proportionalre­gelventil 20, dessen Elektromagnet 21 über eine Stellei­tung 22 gleichermaßen an den Regler 10 angeschlossen ist. Das Innengehäuse 4 geht in eine Abgasleitung 23 über, in der ein Ventilator 24 angeordnet ist, dessen zugehöriger Motor von einer Stelleitung 25 mit Betriebsspannung be­ aufschlagt ist, die von einem Drehzahlregler 26 stammt. Dem Ventilator ist ein Drehzahl-Ist-Wertgeber 27 zuge­ordnet, der über eine Meßleitung 28 mit dem Drehzahlreg­ler 26 verbunden ist. Ein Drehzahl-Soll-Wert wird dem Drehzahlregler über eine Leitung 29 zugeführt, die vom Regler 10 ausgeht. An den Regler 10 ist ein Soll-Wertge­ber 30 angeschlossen, mit dem ein Soll-Wert für die Vor­lauftemperatur der Heizungsanlage vorgebbar ist. Das Außengehäuse 2 ist mit einem Außenrohr 31 verbunden, das sich konzentrisch und im Abstand 32 zum Abgasrohr 23 er­streckt, das das Innenrohr bildet. Die Länge des konzen­trischen Doppelrohrs 31/23 vom Einbauort des Ventilators unmittelbar noch im Gerät bis zu einem Durchbruch durch eine Begrenzungsmauer 33 des Aufstellungsraums ist nahezu beliebig lang, in der Praxis auf einen Bereich von drei bis fünf Meter allerdings längstens begrenzt. Das Doppel­rohr geht durch die Wand hindurch und endet in einem Kopf 34 in der Außenatmosphäre. Dem Zuluftweg ist ein Anemome­terfühler 35 zugeordnet, der ein stetiges Signal für den Luftdurchsatz über eine Leitung 36 an ein Anemometer 37 meldet. Ein weiterer Eingang des Anemometers wird von der Leitung 22 gebildet, und Ausgangssignale des Anemometers werden einmal über eine Leitung 38, hier ein Freigabesig­nal, und über eine Leitung 39, hier ein Korrektursignal, an den Regler 10 gegeben.The flow line 7 is provided with a circulation pump 11, the drive motor 12 of which is supplied with operating voltage from the controller 10 via a line 13. The flow line 7 leads downstream of the pump 11 to a heating system 14, which consists of a plurality of radiators, underfloor heating sections or a domestic hot water tank connected in series and / or in parallel, to which the return line 6 is connected on the return side. The heat exchanger 5 is heated by a gas burner 15, which is fed from a gas line 16, in which a shut-off valve 17 is arranged, the electromagnet 18 of which is fed by a control line 19 which originates from the controller 10. In the gas line 16 there is a proportional control valve 20, the electromagnet 21 of which is equally connected to the controller 10 via a control line 22. The inner housing 4 merges into an exhaust gas line 23, in which a fan 24 is arranged, the associated motor of which is supplied from an actuating line 25 with operating voltage is opened, which comes from a speed controller 26. A speed actual value transmitter 27 is assigned to the fan and is connected to the speed controller 26 via a measuring line 28. A speed setpoint value is fed to the speed controller via a line 29 which starts from the controller 10. A target value transmitter 30 is connected to the controller 10, with which a target value for the flow temperature of the heating system can be specified. The outer housing 2 is connected to an outer tube 31, which extends concentrically and at a distance 32 from the exhaust pipe 23, which forms the inner tube. The length of the concentric double pipe 31/23 from the installation location of the fan directly in the device to a breakthrough through a boundary wall 33 of the installation space is almost as long as possible, but in practice is limited to a range of three to five meters. The double tube passes through the wall and ends in a head 34 in the outside atmosphere. An anemometer sensor 35 is assigned to the supply air path and reports a continuous signal for the air throughput to an anemometer 37 via a line 36. A further input of the anemometer is formed by line 22, and output signals of the anemometer are sent to controller 10 via line 38, here an enable signal, and via line 39, here a correction signal.

Die Funktion der Erfindung wird nunmehr anhand der Dia­gramme der Figuren zwei und drei näher erläutert.The function of the invention will now be explained in more detail with reference to the diagrams in FIGS. Two and three.

Es muß zunächst vorausgeschickt werden, daß das Gerät im Regler 10 einen Temperaturregler aufweist. Der Ist-Wert der Vorlauftemperatur wird vom Fühler 8 erfaßt und über die Leitung 9 dem Regler 10 gemeldet. Es findet ein Ver­gleich zum am Soll-Wertgeber 30 vorgegebenen Temperatur-­Soll-Wert statt, und bei einer Regelabweichung wird das Gerät in Betrieb gesetzt. Hierzu wird zunächst der Magnet 18 erregt, so daß das Gasventil 17 voll öffnet. Ent­sprechend der Größe der Regelabweichung resultiert auf der Leitung 22 ein mehr oder weniger großes Stellsignal, so daß der Magnet 21 mit Teillast- oder Vollastwerten beaufschlagt wird, so daß das Ventil 20 mehr oder weniger stark öffnet. Gleichzeitig wird über die Leitung 22 dem Anemometer 37 ein Soll-Wert für einen hierzu passenden Luftdurchsatz vorgegeben. Bevor aber das Gas freigegeben wird, wird zunächst über die Leitung 29 der Drehzahlreg­ler 26 aktiviert, so daß der Ventilator 24 zunächst mit Maximaldrehzahl anläuft und dann auf einen dem zu erwar­tenden Gasdurchsatz passenden Wert reduziert wird. Mit dieser Drehzahl wird dann im Regelkreis 27, 28, 26, 25 die Drehzahl des Ventilators geregelt. Der sich aufgrund des Arbeitens des Ventilators einstellende Verbrennungs­luftdurchsatz wird aus der Atmosphäre über den Kopf 34 gefördert und durchsetzt den Zuluftpfad, der dem Abstand 32 außerhalb des Gerätes entspricht. Innerhalb des Ge­rätes ist der Zuluftpfad der Abstand der beiden Gehäuse 2 und 4, in dem der Anemometerfühler 35 angeordnet ist. Der sich einstellende Luftdurchsatz wird als Ist-Wert von ihm gemessen und über die Leitung 36 auf das Anemometer ge­geben. Es findet hier ein Soll-Ist-Vergleich statt, und bei Überschreiten eines zu dem zu erwartenden Gasdurch­satz passenden Mindestdurchsatzes wird über die Leitung 38 der Regler 10 freigegeben, so daß nunmehr die beiden Gasventile 17 und 20 entsprechend öffnen können. Das am Brenner 15 austretende Gas wird gezündet, der Brenner brennt und beheizt den Wärmetauscher 5, die Vorlauftempe­ratur steigt. Unterschreitet der Ist-Luftdurchsatz die je nach Gasdurchsatz variable Mindestschwelle, so wird über die Leitung 38 der Regler gesperrt, so daß beide Gasven­tile schließen.It must first be stated that the device in the controller 10 has a temperature controller. The actual value of the flow temperature is detected by sensor 8 and reported to controller 10 via line 9. A comparison is made with the temperature target value specified on the target value transmitter 30, and the device is put into operation in the event of a control deviation. For this purpose, the magnet 18 is first excited so that the gas valve 17 opens fully. Depending on the size of the control deviation, a more or less large control signal results on line 22, so that the magnet 21 is subjected to partial load or full load values, so that the valve 20 opens more or less. At the same time, a setpoint value for a suitable air throughput is given to the anemometer 37 via line 22. Before the gas is released, however, the speed controller 26 is first activated via the line 29, so that the fan 24 first starts at the maximum speed and is then reduced to a value which is suitable for the expected gas throughput. The speed of the fan is then regulated in control loop 27, 28, 26, 25 at this speed. The combustion air flow rate which arises due to the fan working is generated from the atmosphere via the head 34 promotes and penetrates the supply air path, which corresponds to the distance 32 outside the device. Within the device, the supply air path is the distance between the two housings 2 and 4 in which the anemometer sensor 35 is arranged. The air flow rate which arises is measured as an actual value by the latter and is fed via line 36 to the anemometer. A target-actual comparison takes place here, and if a minimum throughput matching the expected gas throughput is exceeded, the controller 10 is released via the line 38, so that the two gas valves 17 and 20 can now open accordingly. The gas emerging from the burner 15 is ignited, the burner burns and heats the heat exchanger 5, and the flow temperature rises. If the actual air throughput falls below the minimum threshold which is variable depending on the gas throughput, the controller is blocked via line 38, so that both gas valves close.

Der Zusammenhang zwischen dem Soll-Wert für den Drehzahl­regler auf der Leitung 29 und dem Ist-Wert des Gasdurch­satzes, entsprechend einer bestimmten Spannung auf der Leitung 22, ist fest. Keineswegs fest ist aber der Zu­sammenhang zwischen dem sich einstellenden Luftdurchsatz und dem Ist-Wert der Ventilatordrehzahl. Weiterhin fest ist der Zusammenhang zwischen dem Ist-wert des Gasdurch­satzes und der Abschaltschwelle für das Anemometer.The relationship between the target value for the speed controller on line 29 and the actual value of the gas throughput, corresponding to a certain voltage on line 22, is fixed. However, the relationship between the air flow rate and the actual value of the fan speed is by no means fixed. The relationship between the actual value of the gas throughput and the switch-off threshold for the anemometer is also fixed.

Um nun unabhängig von der Länge und den Widerständen im Wärmetauscher (aufgrund von einsetzender Verschmutzung) und der Länge und dem Zustand der Rohre einen Luftdurch­satz aufrechtzuerhalten, der mit Sicherheit die jeweilige Abschaltschwelle überschreitet, aber nicht so groß wird, daß ein Betrieb mit minderem Wirkungsgrad der Wärmequelle erfolgt, wird nunmehr erfindungsgemäß wie folgt verfahren:In order to maintain an air throughput regardless of the length and the resistance in the heat exchanger (due to the onset of contamination) and the length and condition of the pipes, which will surely exceed the respective switch-off threshold, but will not become so large that operation with reduced efficiency Heat source takes place, the procedure according to the invention is now as follows:

In der Figur zwei ist in der Abszisse die Spannung USMV für den Öffnungsgrad des Gasmagnetventils aufgetragen, in der Ordinate die Werte für den Gasdurchsatz Q und für den Soll- beziehungsweise Ist-Wert der Drehzahl des Venti­lators. Der schräge Teil der Kurven bedeutet den Modu­lationsbereich, der waagerechte Teil den Vollastzustand. Die Nullpunktverschiebung kommt dadurch zustande, daß man unterhalb eines bestimmten Teillastbereiches ein Arbeiten des Gerätes unterdrücken will.In the figure two, the voltage USMV for the degree of opening of the gas solenoid valve is plotted in the abscissa, the values for the gas throughput Q and for the desired or actual value of the speed of the fan are plotted in the ordinate. The sloping part of the curves means the modulation range, the horizontal part the full load state. The zero point shift comes about because one wants to suppress working of the device below a certain partial load range.

Die Figur drei zeigt neben der Kurve Q für den Gasdurch­satz zusätzlich die Kurven für die Spannung des Anemo­meters (UA) und die Spannung der Abschaltschwelle (US). Zwischen den Kurven US und Q liegt ein Abstand 50. Die Kurve US definiert die Abschaltschwelle. Die Kurve US ist so gelegt, daß sie unter Berücksichtigung der gerätetypi­schen Eigenschaften noch eine hygienisch einwandfreie Verbrennung zuläßt. Unterschreiten dieser Schwelle be­dingt also eine unhygienische Verbrennung und muß daher auf jeden Fall vermieden werden. Die Spannung UA ist eine interne Spannung im Anemometer 37, sie ist mit dem Signal des Anemometerfühlers 35 variabel. Decken sich die Kurven US und UA, so bedeutet das, daß die Verbrennung gerade noch hygienisch ist. Andererseits bedeutet ein Ausein­anderklaffen der Kurven von US und UA einen Betrieb mit einem Wirkungsgrad, der um so schlechter wird, je weiter die Kurven auseinanderliegen. Während die Kurve US in ihrer Lage nicht beeinflußbar ist, hängt die Kurve UA vom Ist-Luftdurchsatz ab. Dieser wird beeinflußt durch die Ventilatordrehzahl und durch Änderungen im gesamten Luft­abgassystem der Wärmequelle, beispielsweise auch durch Verschmutzung. Es wird nun angestrebt, den Wert von UA möglichst dicht an den Wert von US zu legen, ohne daß der Wert für US aber erreicht oder unterschritten wird. Hierzu besitzt das Anemometer 37 einen Differenzbildner und bildet die Differenz zwischen dem Ist-Wert des Luft­durchsatzes, gegeben vom Fühler 35, ausgedrückt durch UA und dem Wert der Abschaltschwelle US. Diese Differenz ist abhängig von der Gerätebelastung, das heißt, von dem Öffnungszustand des Magnetventils 20/21, das heißt ab­hängig von den auf der Leitung 22 herrschenden Signalen. Die Differenz wird mit einem Soll-Wert verglichen, der im Anemometer 37 vorgebbar ist. Eer Soll-Wert kann konstant sein, kann auch über die Gerätebelastung variabel sein. Bei Unterschreiten einer vorgebbaren Größe dieser Diffe­renz wird die Drehzahl des Ventilatormotors erhöht und bei Unterschreiten erniedrigt, indem der Soll-Wert für den Drehzahlregler 26 über die Leitung 39 und den Regler 10 nachgeführt wird. Dieses Variieren der Drehzahl führt dann zu einer Verschiebung der Kurve UA in Richtung Korrektur. Die Differenz ist durch den Abstand 50 definiert.In addition to curve Q for the gas throughput, FIG. Three additionally shows the curves for the voltage of the anemometer (UA) and the voltage of the switch-off threshold (US). There is a distance 50 between the curves US and Q. The curve US defines the switch-off threshold. The curve US is laid out in such a way that, taking into account the properties typical of the device, it is still hygienically perfect Allows combustion. Falling below this threshold therefore results in unsanitary combustion and must therefore be avoided in any case. The voltage UA is an internal voltage in the anemometer 37, it is variable with the signal from the anemometer sensor 35. If the curves US and UA coincide, this means that the combustion is just hygienic. On the other hand, a widening of the curves of the US and UA means an operation with an efficiency that gets worse the further the curves are apart. While the position of curve US cannot be influenced, curve UA depends on the actual air flow. This is influenced by the fan speed and by changes in the entire air exhaust system of the heat source, for example also by pollution. The aim now is to set the value of UA as close as possible to the value of US, but without reaching or falling below the value for US. For this purpose, the anemometer 37 has a difference generator and forms the difference between the actual value of the air throughput, given by the sensor 35, expressed by UA and the value of the switch-off threshold US. This difference is dependent on the load on the device, that is to say on the open state of the solenoid valve 20/21, that is to say on the signals prevailing on the line 22. The difference is compared with a target value, which in the Anemometer 37 can be predetermined. The target value can be constant, but can also be variable via the load on the device. If the value of this difference falls below a predeterminable size, the speed of the fan motor is increased and if it falls below this, the target value for the speed controller 26 is tracked via the line 39 and the controller 10. This variation of the speed then leads to a shift of the curve UA in the direction of correction. The difference is defined by the distance 50.

Claims (1)

1. Verfahren zum Regeln des Verbrennungsluftdurch­satzes für eine brennstoffbetriebene Wärmequelle mit einem Ventilator, dessen Antriebsmotor dreh­zahlvariabel ist, einem stetigen Ist-Wertgeber für den Luftdurchsatz und mit einer Einrichtung zum Abschalten der Brennstoffzufuhr beim Unter­schreiten eines Mindestluftdurchsatzes, dadurch gekennzeichnet, daß die Differenz (50) zwischen dem Ist-Wert (35) des Luftdurchsatzes und einer Abschaltschwelle (US) gebildet wird und daß bei Unterschreiten einer vorgebbaren Größe der Differenz die Drehzahl des Ventilatormotors (24) erhöht und bei Überschreiten erniedrigt wird.1. Method for regulating the combustion air throughput for a fuel-operated heat source with a fan, the drive motor of which is variable in speed, a constant actual value transmitter for the air throughput and with a device for switching off the fuel supply when the airflow falls below a minimum, characterized in that the difference (50) is formed between the actual value (35) of the air throughput and a switch-off threshold (US) and that the speed of the fan motor (24) is increased when the value falls below a predeterminable size and is reduced when it is exceeded.
EP88730029A 1987-02-07 1988-02-06 Method for regulating the flow of combustion air in a fuel-heated heat source Expired - Lifetime EP0279771B1 (en)

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DE3703839 1987-02-07
DE3703839 1987-02-07

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EP0612960A1 (en) * 1993-02-26 1994-08-31 General Electric Company Draft inducer air flow control
GB2304878A (en) * 1995-09-12 1997-03-26 Satermic S L Forced draft controlling device for gas-oil heaters
EP1002998A2 (en) * 1998-11-20 2000-05-24 Robert Bosch Gmbh Heater

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US5676069A (en) 1993-02-22 1997-10-14 General Electric Company Systems and methods for controlling a draft inducer for a furnace
US5680021A (en) 1993-02-22 1997-10-21 General Electric Company Systems and methods for controlling a draft inducer for a furnace
US5616995A (en) 1993-02-22 1997-04-01 General Electric Company Systems and methods for controlling a draft inducer for a furnace
US5682826A (en) 1993-02-22 1997-11-04 General Electric Company Systems and methods for controlling a draft inducer for a furnace
CN109612073B (en) * 2018-12-17 2021-03-23 成都前锋电子有限责任公司 Ignition control method for self-adaptive flue pressure change of gas water heater and wall-mounted boiler

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EP0612960A1 (en) * 1993-02-26 1994-08-31 General Electric Company Draft inducer air flow control
US5418438A (en) * 1993-02-26 1995-05-23 General Electric Company Draft inducer air flow control
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GB2304878A (en) * 1995-09-12 1997-03-26 Satermic S L Forced draft controlling device for gas-oil heaters
EP1002998A2 (en) * 1998-11-20 2000-05-24 Robert Bosch Gmbh Heater
EP1002998A3 (en) * 1998-11-20 2003-01-02 Robert Bosch Gmbh Heater

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EP0279771B1 (en) 1994-12-14
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