EP1717514B1 - Gas burner and methods for starting and operating the same - Google Patents

Description

The invention relates to a gas burner device according to the preamble of patent claim 1 and to a method for switching between two operating states in a gas burner device according to the preamble of claim 17.

Gas burner devices are often used in gas heaters of mobile devices, eg. As caravans, motorhomes or boats to heat comfortably via heat exchanger air or water. As a fuel gas, in particular in mobile devices, LPG, such. As butane or propane used.

Burner controls for such gas heaters must meet some of the safety requirements set out in relevant standards (EN 624 - "Gas heaters for recreational equipment and boats"; EN 298 - "Safety requirements for burner controls of gas heaters").

When starting a gas heater often causes the ignition of a gas flame at the gas burner difficulties. The reason for this is that the right stoichiometric ratio of the fuel gas (butane, propane, or mixtures of both) with the combustion air must be established from the beginning to minimize exhaust emissions at startup. Among other things, the stoichiometric ratio also depends on the combustion air temperature, which may be between -30 ° C and + 70 ° C or more, especially for mobile devices. Due to these large differences, in principle, the correct stoichiometric ratio between fuel gas and combustion air can never be achieved from the start.

Another problem with starting the gas burner is the noise during ignition. When the fuel gas is ignited, the gas burner generally produces a clearly audible "wupp" that may be distracting to the user.

It is known to pre-rinse the combustion chamber in which the flame should form, before starting the gas burner with combustion air, then set a combustion air blower to a fixed speed, a solenoid valve for the Open fuel gas supply and finally ignite in the flammable atmosphere (mixture of fuel gas and combustion air) with a spark plug. When the flame burns, the gas burner will start the regulated operation. On the other hand, if the flame goes out again, a flame detector detects this and tries to ignite for about 10 seconds by releasing the ignition spark. If this fails, the solenoid valve is closed and the heater goes into the fault state.

Usually, combustion takes place in the gas burner at an air ratio λ of about 1.1 to 1.3. The air ratio λ corresponds to the ratio of an actual amount of air supplied to a combustion process (reaction) to a minimum amount of air theoretically required in the case of complete (ideal stoichiometric) combustion. With an air ratio λ of 1.0, therefore, exactly as much combustion air is supplied as is necessary in order to completely burn the fuel gas. In practice, however, such an ideal combustion will never be achieved due to incomplete mixing of the reactants at an air ratio λ of 1.0, so that the air ratio λ is set to the above-mentioned range of 1.1 to 1.3, by one To achieve combustion air surplus.

Since the density of the combustion air depends on the temperature, the air ratio λ is also dependent on the combustion air temperature. If z. B. the temperature of the combustion air is low, the air ratio λ increases, so that although the content of CO in the exhaust gas decreases, but the proportion of nitrogen oxides increases and the exhaust gas loss increases. On the other hand, if combustion air with a higher temperature is available, the air ratio λ drops below the ideal value, so that the exhaust gas loss also increases (poor energy yield) and the CO content increases. In both cases, the combustion is no longer in the optimal working range.

The connections are in Fig. 1 shown schematically. Fig. 1 shows a diagram with the dependence of the concentration of flue gas components and the exhaust gas loss of the air ratio λ. From the curves, the above representation results. The marked area corresponds to an air ratio λ between 1.1 and 1.3 and represents an optimal working area.

When starting is due to the still cold combustion chamber, the unsteady Flow conditions and the inaccurate, in a certain range random ignition point the CO formation higher than desired. In addition, always the above-mentioned "Wupp" sound.

In EP 0 890 791A a control device for a burner is shown, which controls the amount of fuel supplied to a combustion chamber by means of a motor-driven actuator and the combustion chamber supplied air flow by means of a driven by a variable speed motor fan. According to the invention means for detecting the instantaneous speed of the fan are provided, so that the position of the actuator can be tracked due to the signal supplied by the means.

In EP 0 614 046 A is to simplify the construction of a gas-burner control of heating systems, which are to have a high efficiency and low-emission operation even in partial load ranges, a control and regulating device shown in which an adjusting device for the air has a variable speed fan. The fan can be driven by a DC motor, which can be controlled by, in particular, digital pulse-width-modulated control signals of a control unit. The controller acts on the Steueragregat. The gas valve is readjusted as a function of the air pressure in the line leading from the fan to the burner.

The EP 0 615 095 A shows an automatic burner control for controlling a blower with a fan drive and a fuel pump with a fuel pump drive. The automatic burner control unit has a programmer which controls and monitors a commissioning operation and a continuous operation, wherein the blower and the fuel pump are controlled for each operating point in accordance with the data stored in a desired data memory. According to the invention, the setpoint value for the blower drive is corrected according to a predetermined algorithm by the current supply air temperature measured with a supply air temperature sensor. This makes it possible to reduce pollutant emissions.

The invention has for its object to provide a gas burner device that can be started and operated at different ambient air temperatures (= combustion air temperature).

According to the invention, a gas burner device according to claim 1 is specified. A method for changing the operating state of a gas burner device is set forth in claim 17. Advantageous developments of the invention are defined in the dependent claims.

A gas burner device according to the invention comprises a gas burner for burning a combustion gas combustion air mixture and a combustion air blower having a combustion air engine for supplying the combustion air to the gas burner. With the help of the combustion air blower, the combustion air is sucked from the environment and fed to the gas burner, where it mixes with the fuel gas.

• Ansteuern der Drehzahleinstelleinrichtung zum Einstellen der Drehzahl des Verbrennungsluftmotors auf eine dem Ausgangsbetriebszustand entsprechende Ausgangsdrehzahl;
• Ansteuern der Drehzahleinstelleinrichtung zum im Wesentlichen kontinuierlichen Ändern der Drehzahl von der Ausgangsdrehzahl auf eine dem Zielbetriebszustand entsprechende Zieldrehzahl während eines vorbestimmten Zeitabschnitts;
• während des vorbestimmten Zeitabschnitts Ansteuern des Brenngasventils zum Ändern der Brenngaszufuhr auf eine dem Zielbetriebszustand entsprechende Ziel-Brenngaszufuhr.

The combustion air motor can be adjusted by a speed setting device to at least two different rotational speeds, but in particular to any rotational speeds within a working range. According to the present invention, there is provided a sequence controller that controls a change of an operating state of the gas burner device from an initial operating state to a target operating state having the following sections:

• Driving the speed setting means for setting the rotational speed of the combustion air motor to an output speed corresponding to the output operating state;
• Driving the speed setter to substantially continuously change the speed from the output speed to a target speed corresponding to the target operating condition during a predetermined period of time;
• during the predetermined period of time driving the fuel gas valve for changing the fuel gas supply to a target fuel gas supply corresponding to the target operation state.

Accordingly, with the aid of the sequence control, it is possible to first operate the gas burner device in an initial operating state, so that this state can stabilize. If a change in operating condition is required by the operator or a work program, the sequencer effects an adjustment of the speed of the combustion air motor over a certain, longer period of time. Thus, the speed is not suddenly adjusted from the output speed to the target speed. Rather, a continuous, z. B. linear, relatively slow (over several seconds) change in speed. The output speed and the target speed each depend on the desired output or target operating state.

During this change in the speed, the change in the fuel gas supply caused by the sequence control takes place by the activation of the fuel gas valve. The creation of relatively long time periods for the transition between the initial and the target operating states enables a smooth change between the operating states. Since with the change of operating conditions usually also the amount of supplied fuel gas must be changed, therefore, this fuel gas change is not according to the invention with a sudden change in the combustion air flow, but also in the period while the speed changes. For example, it is possible, as will be explained later, to supply fuel gas to the combustion air when the gas burner is started in a volumetric flow which decreases due to a falling speed, and to ignite it shortly thereafter.

The smooth change between the operating states on the one hand opens up the possibility of always achieving a stable state with regard to the air ratio λ, in which certain compromises can be made with regard to exhaust emission and energy yield. As a result, it can be avoided that suddenly produces a high pollutant emissions. In addition, it has been found that the change in the operating state in the manner according to the invention, the noise occurring in the prior art can be significantly reduced or completely avoided.

In a particularly advantageous embodiment of the invention is a temperature detection device provided for detecting the temperature of the combustion air. The speed setting device is coupled to the temperature detecting device such that the rotational speed is adjustable as a function of the combustion air temperature.

In this way, it is very easily possible that always the amount of combustion air is supplied to the gas burner, which is required for the desired air ratio λ (ratio of combustion air and fuel gas). It does not matter with what temperature the combustion air is supplied. The differences in density resulting from different combustion air temperatures are compensated by the speed controllability of the combustion air motor. At low temperatures, the combustion air has a higher density, so that a lower volume flow of combustion air is sufficient to achieve the same air ratio λ. Accordingly, the combustion air motor can be operated at a lower speed. If, on the other hand, the combustion air temperature rises, the density of the combustion air decreases correspondingly, so that the speed of the combustion air engine must be increased in order to supply the same amount of combustion air to the gas burner.

• Ansteuern der Drehzahleinstelleinrichtung zum Einstellen der Drehzahl des Verbrennungsluftmotors auf eine der Ausgangsdrehzahl entsprechende Startdrehzahl;
• Ansteuern der Drehzahleinstelleinrichtung zum im Wesentlichen linearen, kontinuierlichen Absenken der Drehzahl von der Startdrehzahl auf eine niedrigere, der Zieldrehzahl entsprechende Betriebsdrehzahl während eines Verstreichens des Zeitabschnitts TS, wobei die Drehzahl zu Beginn des Zeitabschnitts TS der Startdrehzahl und zum Ende des Zeitabschnitts TS der Betriebsdrehzahl entspricht;
• Ansteuern eines Brenngasventils zum Öffnen einer Brenngaszufuhr zu der Verbrennungsluft während des Zeitabschnitts TS; und
• nach dem Öffnen der Brenngaszufuhr Ansteuern der Zündeinrichtung zum Zünden des Brenngases während des Zeitabschnitts TS.

In a particularly preferred embodiment of the invention, a starting device is provided which has an ignition device for igniting the fuel gas and a timer for generating at least a predetermined period of time TS. Furthermore, the sequence control has a start-up sequence control, which controls a starting operation of the gas burner device with the following sections:

• Driving the speed setting means for setting the speed of the combustion air motor to a starting speed corresponding to the output speed;
• Driving the speed setting means for substantially linearly, continuously decreasing the speed from the starting speed to a lower operating speed corresponding to the target speed during a lapse of the period TS, the speed corresponding to the start speed at the beginning of the period TS and the operating speed at the end of the period TS;
• Driving a fuel gas valve to open a fuel gas supply to the combustion air during the period TS; and
• after opening the fuel gas supply driving the ignition device for igniting the fuel gas during the period TS.

Thus, an increased speed of the combustion air engine (start speed) is initially set using the start-flow control. Thereafter, the start sequencer reduces the speed slowly during the time period TS, ie continuously and substantially linearly from the starting speed to the lower operating speed. The time period TS can be a few seconds, z. B. 7.5 seconds, take. During the reduction of the rotational speed, in particular shortly before reaching the operating speed, the start-up control controls the fuel gas valve in order to open the fuel gas supply and mix the combustion air fuel gas. The opening of the fuel gas valve thus takes place during the lowering of the speed of the combustion air engine and thus in the decreasing combustion air volume flow into it.

After opening the fuel gas valve, the ignition device, for. As a spark plug, driven to ignite the fuel gas during the period TS, so even before reaching the operating speed.

The starting device is able to repeat this starting process several times if no flame is detected at the gas burner after the start of a boot process. This will be explained later.

In a particularly preferred embodiment of the invention, the starting device has a rotational speed detection device in order to detect the rotational speed of the combustion air engine. As a result, the function of the combustion air engine can always be monitored. In particular, it is possible to check whether the combustion air engine, the predetermined speed, ie the starting speed, and the temperature-dependent operating speed complies. If the actual speed deviates from the setpoint speed, the speed setting device can correctively intervene and adjust the actual engine speed accordingly.

In a particularly advantageous embodiment of the invention, the start-up sequence control is designed such that the achievement of a predetermined, between the starting speed and the operating speed lying opening speed is determined, and that upon reaching the opening speed during the period TS, the fuel gas valve is opened. The speed detection device makes it possible to determine very precisely the right moment for the opening of the fuel gas valve, namely the reaching of the opening speed. The opening speed may be determined in advance so that the fuel gas valve is not opened at any time within the period TS, but at a time at which a combustion air volume flow is achieved, which is optimal for the starting process. In this way, the noise at start can be further reduced significantly.

Preferably, the start-flow control can also be designed such that the speed detection device during the period TS, the achievement of a predetermined, lying between the opening speed and the operating speed ignition speed is determined, and that upon reaching the ignition speed, the ignition device is driven to the Ignite fuel gas. The ignition speed can be determined in advance in such a way that it causes an optimum volume flow for the combustion air, with which the fuel gas combustion air mixture can be reliably ignited.

• Überwachen eines Verstreichens des ersten Zeitabschnitts TW nach dem Eingeben eines Startbefehls durch einen Bediener über ein mit der Start-Ablaufsteuerung verbundenes Bedienelement und/oder Überwachen eines Verstreichens des ersten Zeitabschnitts TW nach dem Erreichen der Startdrehzahl durch den Verbrennungsluftmotor; und
• nach Ablauf des ersten Zeitabschnitts TW Ansteuern der Drehzahleinstelleinrichtung zum Absenken der Drehzahl während des zweiten Zeitabschitts TS.

In a particularly advantageous embodiment of the invention, the time period TS represents a second time period, which is preceded by a first time period TW. The boot sequencer then controls the boot process with the following sections:

• Monitoring a lapse of the first time period TW after inputting a start command by an operator via an operation element connected to the startup flow control and / or monitoring a lapse of the first time period TW after reaching the startup speed by the combustion air motor; and
• after expiration of the first time interval TW, driving the speed setting device to lower the speed during the second time interval TS.

Thus, a time period TW is preceded before the above-mentioned time period TS and the measures taken during this period TS, which over a certain time, for. B. a few seconds, expires, and during which the starting speed of the combustion air motor is to stabilize. It is possible that the starting speed has already been reached before the start of the time period TW and then only has to be kept constant during this time period. Alternatively, it is also possible that the starting speed is set only at the beginning of the period TW.

The operator or the start-up sequence control initiates the setting of the starting rotational speed of the combustion air engine, which is stabilized over the first time period TW. Only then does the second time period TS follow, in which the rotational speed is lowered from the starting rotational speed to the operating rotational speed, the fuel gas supply is opened and the fuel gas combustion air mixture is ignited.

In another embodiment of the invention, the sequence controller comprises a changing device for switching between an output gas level corresponding to the initial operating state and a target gas level corresponding to the target operating state, wherein the output gas level and the target gas level respectively correspond to first and second gas levels and vice versa. The first gas stage corresponds to a fuel gas supply with a first, lower volume flow, while the second gas stage corresponds to a fuel gas supply with a second higher volume flow. Accordingly, a lower, first operating speed is provided for the first gas stage and a higher, second operating speed of the combustion air engine for the second gas stage.

• Ansteuern der Drehzahleinstelleinrichtung zum im Wesentlichen linearen Ändern der Drehzahl von der der Ausgangsgasstufe entsprechenden Drehzahl auf die der Zielgasstufe entsprechenden Drehzahl während eines Verstreichens eines Wechsel-Zeitabschnitts TC; und
• Ansteuern des Brenngasventils zum Ändern einer Brenngaszufuhr zu der Verbrennungsluft während des Wechsel-Zeitabschnitts TC auf einen der Zielgasstufe entsprechenden Zustand.

The changing device now allows a particularly comfortable change between the gas levels. For this purpose, the changing device has a change sequence control, which controls the change process with the following sections:

• Driving the speed setting means for substantially linearly changing the speed from the speed corresponding to the output gas level to the speed corresponding to the target gas level during elapse of a changeover time period TC; and
• Driving the fuel gas valve to change a fuel gas supply to the combustion air during the changeover time period TC to a state corresponding to the target gas level.

Accordingly, here too the change of the rotational speed takes place over a longer period of time, namely the changeover time interval TC. The switching of the fuel gas valve, ie increasing or decreasing the fuel gas supply (depending on the desired Target gas level), likewise takes place during the changeover time interval TC, that is to say into the change of the speed of the combustion air engine. Thus, as with the starting operation described above, the switching of the fuel gas valve (opening and closing at the time of starting, changing the fuel gas volume flow when the gas levels are switched) takes place during a transitional period (time period TS, changeover time period TC) in which the number of revolutions of the combustion air engine including a fan operates in the combustion air blower changes.

The change sequence control is preferably designed such that a triggering of the fuel gas valve for changing the fuel gas supply at the earliest after expiration of a portion of the change period TC, in particular after expiration of 20% of the change period TC occurs. For example, the driving of the fuel gas valve may be performed at about the middle of the changeover period TC. Here, a compromise between a too low and a high air ratio λ must be found. However, the opening of the fuel gas valve may occur at another time within the changeover time period TC than the closing.

As a criterion for the correct opening time, the speed of the combustion air motor detected by the speed detection device can also be evaluated again, similar to the above when starting.

In a particularly advantageous embodiment of the invention, a Zündüberwachungseinrichtung is provided with a detector for monitoring a firing of a flame at the gas burner. In this way it can be ensured that, if necessary, a fault of the gas burner device is detected, which would otherwise cause an uncontrolled outflow of the unburned fuel gas.

The ignition monitoring device is preferably coupled to the start-up sequence control in such a way that the starting process can be repeated by the start-up sequence if, after the end of a starting operation by the ignition monitoring device, it is determined that no flame is burning on the gas burner.

In addition, a security timer can be used to determine a total time period be provided from the beginning of the first start operation, wherein the start-up sequence control does not allow any further starting operation when the total period has exceeded a predetermined period of time, without being detected by the Zündüberwachungseinrichtung a flame on the gas burner. Accordingly, during the predetermined time period, the starting process can be repeated several times. On the other hand, after the expiration of the period of time, it is assumed that there is a malfunction of the device which requires intervention by the operator. Thus, in this case, no fuel gas exits uncontrolled, the start-flow control closes the fuel gas supply reliable and goes to trouble operation.

Alternatively or additionally, a security counter may be provided for determining a total number of startup operations. The start sequencer then refuses to start again if the total number has exceeded a predetermined value without the ignition monitoring device detecting the presence of a flame on the gas burner.

Moreover, in a preferred embodiment of the invention, it is possible that the start-up sequence control initiates no further starting operation if the total number of start operations reaches a predetermined value within a predetermined period without the ignition monitoring device detecting a flame on the gas burner.

An inventive method for changing an operating state of a gas burner device from an initial operating state to a target operating state is characterized by the steps of: setting the combustion air motor to an output speed corresponding to the initial operating state; during a predetermined period of time, substantially continuously changing the rotational speed of the combustion air engine from the output rotational speed to a target rotational speed corresponding to the target operating state; during the predetermined period of time, changing the fuel gas supply to a target fuel gas supply corresponding to the target operation state. The method ensures the above-described smooth change between operating conditions of the gas burner device.

A preferred embodiment of the method is suitable for starting a gas burner device and is characterized by the steps: setting the Combustion air engine to a starting speed (output speed); substantially continuously decreasing the speed of the combustion air motor from the starting speed to an operating speed (target speed) during a period of time TS; during the lowering of the speed of opening a fuel gas supply and after the opening of the fuel gas supply and before the end of the period TS ignition of the fuel gas. The ignition of the fuel gas takes place in this way in the lowering of the speed, which supports a soft ignition, so that the often perceived as disturbing "wupp" noise is reduced or completely prevented.

In a preferred embodiment of the invention, it is checked before lowering the speed, whether the combustion air engine rotates at the starting speed. Only when the combustion air engine actually reaches the higher than the operating speed starting speed, the inventively provided lowering the speed is possible.

A particular embodiment of the method is characterized by the steps: measuring the temperature of the combustion air and setting the target speed or operating speed as a function of the temperature of the combustion air.

Fig. 1

in schematischer Darstellung die Konzentration von Rauchgasbestandteilen in Abhängigkeit von der Luftzahl λ;

Fig. 2

ein schematisches Blockschaltbild von einer ersten Ausführungsform der erfindungsgemäßen Gasbrennervorrichtung;

Fig. 3

den Drehzahlverlauf eines Verbrennungsluftmotors beim Starten einer erfindungsgemäßen Gasbrennervorrichtung; und

Fig. 4

den Drehzahlverlauf des Verbrennungsluftmotors beim Wechseln zwischen zwei Gasleistungsstufen.

These and other advantages and features of the invention are explained in more detail below by means of examples with the aid of the accompanying figures. Show it:

Fig. 1

a schematic representation of the concentration of flue gas components as a function of the air ratio λ;

Fig. 2

a schematic block diagram of a first embodiment of the gas burner device according to the invention;

Fig. 3

the speed curve of a combustion air engine when starting a gas burner device according to the invention; and

Fig. 4

the speed curve of the combustion air engine when switching between two gas power levels.

Fig. 2 shows a block diagram of the schematic structure of a first embodiment of the gas burner device according to the invention.

The gas burner device may be part of a gas heater, which is used in particular in boats or recreational vehicles. Accordingly, the hot flue gases are passed to a heat exchanger to deliver the heat to a heat transfer medium in a known manner.

A gas burner 1 serves to burn a mixture of fuel gas and combustion air. The fuel gas is supplied via a fuel gas line 2 from a fuel gas supply 3. In the fuel gas line 2, a fuel gas valve 4 is installed, which opens or closes the fuel gas line 2. The fuel gas valve 4 is preferably designed as a solenoid valve and accordingly electrically switchable. The fuel gas supply 3 is preferably a gas storage bottle, the liquefied gas, eg. As propane or butane or a mixture thereof contains.

Between the fuel gas supply 3 and the fuel gas valve 4, a control device known per se for reducing the pressure in the fuel gas supply 3 (gas storage bottle) advancing high pressure to a suitable for the gas burner 1, significantly lower pressure is provided.

The combustion air is drawn in via a combustion air line through a combustion air blower 6 from the environment and fed to the gas burner 1.

In the gas burner 1, the combustion air mixes with the fuel gas in a certain ratio, so that a gas mixture is generated, which achieves optimum efficiency while simultaneously achieving the best possible exhaust gas quality during combustion.

For this purpose, in the gas burner 1, the correct stoichiometric ratio of fuel gas and combustion air must be established. The air ratio λ, which represents the ratio between a quantity of combustion air actually supplied and a minimum amount of combustion air theoretically required for complete combustion, serves as a yardstick. Fig. 1 shows the concentration of flue gas components in relation to the air ratio λ. from that It can be seen that with an air ratio λ between 1.1 and 1.3 and thus a slight excess of combustion air, optimum combustion can be achieved in which little carbon monoxide is expelled and there is a minimal loss of exhaust gas.

The supply of the fuel gas is substantially constant, because the pressure at which the fuel gas is supplied from the fuel gas supply 3 practically does not change due to the pressure regulator disposed downstream of the fuel gas supply 3 and the pressure reduction operations performed thereby. Accordingly, the air ratio λ can be adjusted mainly by changing the combustion air supply.

For this purpose, it is possible to vary the rotational speed of a combustion air engine 7 driving the combustion air blower 6 via a speed setting device 8. If a special control quality is to be achieved, a speed detection device 9 can additionally be provided which monitors the speed of the combustion air engine 7 and, if necessary, adjusts it with the aid of the speed setting device 8. As a combustion air motor 7 is particularly suitable a PWM motor (PWM: Pulse Width Modulation), since its speed can be controlled equally simple and reliable. The speed of the combustion air motor 7 can be adjusted by the speed setting 8 to any values within a working range.

For the present invention, the operation of starting the gas burner device is important. Therefore, a start-up flow control 10 will be discussed below, which, however, may be part of a general, all-encompassing control of the gas burner device. The start-up sequence control 10 is coupled to the fuel gas valve 4, the speed setting device 8 and, if present, the speed detection device 9. Accordingly, it is able to control both the fuel gas supply and the combustion air supply in response to operator requests entered by the operator via an unillustrated control element and / or control programs stored in the startup flow control 10.

Furthermore, the start-up sequence control is connected to an ignition device 11, with which the combustible fuel gas combustion air mixture exiting the gas burner 1 can be ignited in a known manner. As ignition device 11 is z. As a spark plug that generates a high voltage spark.

In addition, an ignition monitoring device 12 may be provided which detects the presence of a flame on the gas burner 1 and supplies a corresponding signal to the start-up sequence control 10. The ignition monitoring device 12 is therefore particularly necessary in order to avoid an uncontrolled leakage of unburned fuel gas. Namely, when an ignition has failed, there is a fear that fuel gas will leak at the gas burner 1 without being burned. This immediately requires a repetition of the ignition process by the ignition device 11 or a shut-off of the fuel gas supply by the fuel gas valve 4. The Zündüberwachungseinrichtung 12 provides the necessary information to the start-flow control 10, which then initiates the preprogrammed measures.

Furthermore, a temperature detection device 13 is provided, with which the temperature of the gas burner 1 supplied combustion air can be measured. The measurement result is provided to the start-up flow control 10, which accordingly can set the desired operating speed for the combustion air blower 6. As a temperature detecting means 13, a thermocouple or a thermocouple, which measures either the temperature in the environment or in the combustion air line 5 is suitable.

The start-up flow control 10 enables a start-up operation of the gas burner device, as described below with reference to FIG Fig. 3 is explained.

Fig. 3 schematically shows the curve of the rotational speed of the combustion air engine over time when starting the gas burner device.

When switching on the device or when entering an ignition or start command by the operator, the start-flow control 10 controls the Drehzahleinstelleinrichtung 8 such that the combustion air engine 7 rotates at a starting speed nS. The starting speed nS is above an operating speed nB and z. In a range between 1400 and 4500 rpm. For example, the starting speed nS may be set as a fixed speed of about 3200 Be set rpm.

The starting rotational speed nS is maintained and stabilized over a first period TW. In this case, the rotational speed can be controlled via the rotational speed detecting device 9. If it is determined that the preselected starting speed nS (within a certain tolerance range) is not reached, e.g. B. because the combustion air motor 7 is blocked, recognizes the start-flow control 10 an error and aborts the starting process. Depending on the configuration, it can transmit an optical or acoustic error signal to the operator.

During the first time interval TW, the fuel gas valve 4 remains closed, so that only combustion air flows through the gas burner 1.

At the first time period TW, the several seconds, z. B. 3 seconds, a second time period TS connects. In the second period TS, the actual ignition takes place. For this purpose, the rotational speed of the combustion air engine 7 is continuously reduced substantially linearly from the starting rotational speed nS to the predetermined operating rotational speed nB, as in FIG Fig. 3 recognizable. The second period TS can be several seconds, z. B. 7.5 seconds.

First, the speed is lowered over a period c within the second period TS until an opening speed nÖ is reached. With the attainment of the opening speed nÖ the start-flow control 10 opens via the fuel gas valve 4, the fuel gas supply to the gas burner 1. Accordingly, fuel gas mixes with the already existing combustion air flow. A short time later, within a period d, the ignition triggered by the start-flow control 10 takes place via the ignition device 11. At this time, the ignition speed nZ is present at the combustion air engine 7. Since the speed is still above the operating speed nB at this time, the combustion air blower 6 generates a combustion air flow that is too large for the desired combustion, so that there is an excess of air in the gas burner 1. Ignition then takes place in the air surplus (air ratio λ eg greater than 1.3), so that the CO emission is minimal (cf. Fig. 1 ). That at this time the exhaust gas loss is high does not bother, because subsequently the speed is further reduced until the speed reaches the predetermined, ideal value of the operating speed nB. Then the combustion takes place in the gas burner 1 at an air ratio λ of about 1.1 to 1.3.

The reduction of the rotational speed during the second time interval TS may be at different speeds, ie in different sections, as in FIG Fig. 3 shown.

The operating speed nB may depend on the combustion air temperature. For this purpose, it is possible that the operating speed nB changes continuously as a function of the combustion air temperature. Alternatively, several temperature levels can be defined, each corresponding to a suitable operating speed and thus a corresponding combustion air flow. Basically, it is such that higher combustion air temperatures require a larger combustion air flow and thus a higher operating speed nB of the combustion air engine 7.

If the ignition monitoring device 12 detects no flame on the gas burner 1 after ignition, the start-up control 10 attempts to repeat the starting process TS after a waiting time TWI. For this purpose, the speed of the combustion air engine 7 is first increased again to the starting rotational speed nS, whereupon the speed reduction can take place in the time interval TS.

Within a given period of z. For example, a maximum number of starts (for example, three starts) is made for 2 minutes. If no flame is still detected at the gas burner 1 after that, the gas burner device enters a fault state and stops starting. One reason can be z. B. are also in an empty fuel gas supply 3.

The ignition into the excess air not only makes it possible to reduce the CO contents in the flue gas during the starting process. Rather, the usual noise during ignition ("Wupp") is significantly reduced.

In another embodiment of the invention, but which can also be used in addition to the above embodiment, a change between two gas levels is supported.

Thus, it is known that a gas burner device can be operated not only with a single power level, but with multiple power levels.

For example, a first gas stage may be provided with a fuel gas supply with a low volume flow and, accordingly, a first, low operating speed of the internal combustion engine 7. In a second gas stage, the fuel gas is supplied with a higher volume flow, and the operating speed of the combustion air engine 7 is at a higher level.

Even when switching between the gas levels may occur in known gas burners due to the sudden change in air ratio λ to an undesirably high pollutant emissions or disturbing noise.

To solve the switching takes place in a Fig. 4 shown way.

For this purpose, a changing device is provided, which has an alternating sequence control with which the changing process can be controlled. The change sequence control can be used with the above in connection with the Fig. 2 described start sequence control can be combined.

Fig. 4 shows similar to Fig. 3 the speed curve of the combustion air motor 7 when switching between the first and the second throttle stage or when switching between the second and the first throttle stage.

The gas burner is initially in the first gas stage, in which the combustion air engine 7 rotates at the first operating speed n (T, stage 1). The operating speed is - as stated above - dependent on the combustion air temperature T.

When the operator switches from the first gas level to the second gas level, a corresponding operation command is executed by the change schedule and the speed of the combustion air motor 7 is continuously transmitted through the speed setter 8 during a changeover time period TC (eg, 2.5 seconds) elevated. As Fig. 4 shows the increase can be linear. Alternatively, other gradients can be set.

After reaching an opening speed (2600 U / min in the present example), the fuel gas valve 4 is opened, ie adjusted from its first stage to the second stage, so that more fuel gas can reach the gas burner 1.

Subsequently, the second gas stage with the operating speed n (T, level 2) is stabilized.

In a reverse switching operation, namely the switching back from the gas stage 2 to the gas stage 1, the speed of the combustion air motor 7 from the high operating speed n (T, stage 2) is continuously on the low operating speed n of the change sequence control during the change period (T, level 1) reduced. Upon reaching a predetermined closing speed (2700 U / min in the example shown), the fuel gas valve 4 is activated in order to reduce the fuel gas supply to the first gas level.

The opening or closing of the fuel gas valve 4 during the changeover time period TC can take place as a function of the respectively applied switching speed. Likewise, it is also possible to effect the switching after a certain period of time within the changeover period TC.

Claims (22)

1. Gas burner device, with

   - a gas burner (1) for combustion of fuel gas and combustion air;

   - a combustion air fan (6) having a combustion air motor (7) for supplying the combustion air to the gas burner (1); and with

   - a controllable fuel gas valve (4) regulating a fuel gas supply from a fuel reservoir (9) to the gas burner (1);
   characterised in that

   - the combustion air motor (7) can be adjusted to at least two different speeds by a speed regulating device (8), in particular to any desired speed; and that

   - a sequence controller (10) is provided, which controls a change of an operating state of the gas burner device from an initial operating state to a target operating state with the following stages:

   + actuation of the speed regulating device (8) to adjust the speed of the combustion air motor (7) to an initial speed corresponding to the initial operating state;

   + actuation of the speed regulating device (8) to vary the speed substantially continuously from the initial speed to a target speed corresponding to the target operating state for a predetermined period of time (TS; TC);

   + actuation of the fuel gas valve (4) during the predetermined period of time (TS; TC) to alter the fuel gas supply to a target fuel gas supply corresponding to the target operating state.
2. Gas burner device in accordance with claim 1, characterised in that

   - a temperature recording device(13) is provided to record the temperature of the combustion air; and that

   - the speed regulating device (8) is coupled with the temperature recording device (13) so that the speed can be varied as a function of the combustion air temperature.
3. Gas burner device in accordance with claim 1 or 2, characterised in that a starting device is provided, with

   - an ignition device (11) to ignite the fuel gas;

   - a timer to produce the predetermined period of time TS; and with

   - a start sequence controller forming part of the sequence controller (10), which controls a start procedure with the following stages, wherein the start procedure is regarded as a change to the operating state:

   + actuation of the speed regulating device (8) to adjust the speed of the combustion air motor (7) to a start speed (initial speed):

   + actuation of the speed regulating device (8) to reduce the speed substantially linearly from the starting speed to a lower operating speed (target speed) while the time period TS elapses, wherein the speed corresponds to the starting speed at the beginning of the time period TS and to the operating speed at the end of the time period TS;

   + actuation of a fuel gas valve (4) to open a fuel gas supply to the combustion air during the time period TS;

   + after the opening, actuation of the ignition device to ignite the fuel gas during the time period TS.
4. Gas burner device in accordance with claim 3, characterised in that the start sequence controller (10) is configured so that the actuation of the fuel gas valve (4) to open the fuel gas supply takes place at an opening time after a predetermined period of time has elapsed after the start of the time period TS.
5. Gas burner device in accordance with claim 3 or 4, characterised in that the start sequence controller (10) is configured so that the actuation of the ignition device (11) to ignite the fuel gas takes place between the opening time and the end of the time period TS.
6. Gas burner device in accordance with one of the claims 3 to 5, characterised in that the starting device has a speed recording device (9), for recording the speed of the combustion air motor (7).
7. Gas burner device in accordance with one of the claims 3 to 6, characterised in that the start sequence controller (10) is configured so that

   - during the time period TS, the speed recording device (9) can detect when a predetermined opening speed, lying between the starting speed and the operating speed, is reached; and that

   - when the opening speed is reached during the time period TS, the fuel gas valve (4) can be actuated to open the fuel gas supply.
8. Gas burner device in accordance with one of the claims 3 to 7, characterised in that the start sequence controller (10) is configured so that

   - during the time period TS, the speed recording device (9) can detect when a predetermined ignition speed, lying between the opening speed and the operating speed, is reached; and that

   - when the ignition speed is reached during the time period TS, the ignition device (11) can be actuated to ignite the fuel gas.
9. Gas burner device in accordance with one of the claims 3 to 8, characterised in that

   - the time period TS is a second time period;

   - the timer is additionally configured to generate a predetermined first time period TW elapsing before the second time period TS; and that

   - the start sequence controller (10) controls the start procedure with the following stages:

   + monitoring of the passage of the first time period TW, following the input of the start command by the user, by means of an operating element connected to the start sequence controller (10) and/or expiry of the first time period TW after the start speed has been reached by the combustion air motor (7);

   + after the first time period TW has elapsed, actuation of the speed regulating device (8) to reduce the speed during the second time period TS.
10. Gas burner device in accordance with one of the claims 1 to 9, characterised in that

    - the sequence controller has a change-over device for alternating between an initial gas stage (initial operating state) and a target gas stage (target operating state), wherein the initial gas stage is a first gas stage and the target gas stage is a second gas stage or the initial gas stage is the second gas stage and the target gas stage is the first gas stage;

    - the first gas stage corresponds to a fuel gas supply with a first, lower volumetric flow rate and the second gas stage corresponds to a fuel gas supply with a second, higher volumetric flow rate; and that

    - a lower, first operating speed of the combustion air motor (7) is provided for the first stage and a higher, second operating speed for the second gas stage.
11. Gas burner device in accordance with claim 10, characterised in that the change-over device has a change-over sequence controller, which controls the change-over procedure with the following stages:

    - actuation of the speed regulating device (8) to vary the speed substantially linearly from the speed corresponding to the initial gas stage to the speed corresponding to the target gas stage while a change-over time period TC generated by the timer elapses;

    - actuation of a fuel gas valve (4) to alter a fuel gas supply to the combustion air during the change-over time period TC to a state corresponding to the target gas stage.
12. Gas burner device in accordance with claim 11, characterised in that the change-over sequence is configured so that an actuation of the fuel gas valve (4) for altering the fuel gas supply takes place at the earliest after part of the change-over time period TC has elapsed, in particular after of 20% of the change-over time period TC has elapsed.
13. Gas burner device in accordance with one of the claims 1 to 12, characterised in that

    - an ignition monitoring device (12) is provided, with a detector for monitoring an ignition of a flame on the gas burner (1); and that

    - the ignition monitoring device (12) is coupled with the start sequence controller (10), so that the starting procedure can be repeated by the start sequence controller if, after completion of the start procedure, the ignition monitoring device (12) detects that there is no flame on the gas burner (1).
14. Gas burner device in accordance with one of the claims 3 to 13, characterised in that

    - a safety timer is provided for determining an overall time period from the beginning of the first starting procedure; and that

    - no further starting procedure can be actuated by the start sequence controller, if the overall time period has exceeded a predetermined time span and the ignition monitoring device (12) detects that there is no flame on the gas burner (1).
15. Gas burner device in accordance with one of the claims 3 to 14, characterised in that

    - a safety counter is provided for determining a total number of starting procedures; and that

    - no further starting procedure can be actuated by the start sequence controller if the total number has exceeded a predetermined value and the ignition monitoring device (12) detects that there is no flame on the gas burner (1).
16. Gas burner device in accordance with one of the claims 3 to 15, characterised in that no further starting procedure can be actuated by the start sequence controller (10) if, within a predetermined time span, the total number of starting procedures has exceeded a predetermined value and the ignition monitoring device (12) detects that there is no flame on the gas burner (1).
17. Method for changing an operating state of a gas burner device from an initial operating state to a target operating state, whereby the gas burner device has:

    - a gas burner (1) for combustion of fuel gas and combustion air;
    and

    - a combustion air fan (6) having a combustion air motor (7) for supplying the combustion air to the gas burner (1), wherein the speed of the combustion air motor (7) is controllable;
    characterised by the steps:

    - adjustment of the combustion air motor (7) to an initial speed corresponding to the initial operating state;

    - substantially continuous variation of the speed of the combustion air motor (7) from the initial speed to a target speed corresponding to the target operating state for a predetermined period of time (TS; TC);

    - change of the fuel gas supply to a target fuel gas supply corresponding to the target operating state for the predetermined period of time (TS; TC).
18. Method in accordance with claim 17, wherein

    - the initial speed corresponds to a starting speed;

    - the target speed corresponds to an operating speed;

    - the substantially continuous variation of the speed of the combustion air motor (7) corresponds to a substantially continuous decrease of the speed of the combustion air motor (7) from the start speed to the operating speed; and

    - the change of the fuel gas supply to the target fuel gas supply corresponds to an opening of the fuel gas supply (4):

    characterised by the step:

    - after the fuel gas supply (4) has been opened, and before the end of the predetermined time period, ignition of the fuel gas to achieve the target operating state.
19. Method in accordance with claim 18, characterised in that a check is made of whether the combustion air motor (7) is rotating at the starting speed before the speed is decreased.
20. Method in accordance with claim 18 or 19, characterised in that the speed of the combustion air motor (7) is maintained at the starting speed at least over a time period TW before the time period TS begins.
21. Method in accordance with claim 17, wherein

    - a change-over take place between an initial gas stage, corresponding to a specific fuel gas volumetric flow rate, existing in the initial operating state and a target gas stage, corresponding to another fuel gas volumetric flow rate corresponding to the target fuel gas supply, existing in the target operating state; and

    - the change of the speed of the combustion air motor (7) from the initial speed to the target speed corresponds substantially to a linear variation of speed during the passage of a change-over time period TC corresponding to the predetermined time period.
22. Method in accordance with one of the claims 17 to 21, characterised by the steps:

    - measurement of the temperature of the combustion air; and

    - adjustment of the target speed or the operating speed depending on the temperature of the combustion air.

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