EP4060235A1 - Method for operating a heater with an electronic gas / air connection - Google Patents

Abstract

A method for operating a heater (1) with an electronic gas-air compound is proposed, which comprises at least the following steps to be carried out during heating operation: a) moving an opening position of a gas stepping motor valve (31) via an ignition ramp function; b) detecting the ionization current of a flame (4) of the heater (1); c) detecting the opening position of the gas stepping motor valve (31) when a defined limit value of the ionization current is reached; Position of the gas stepping motor valve (31). The method allows an ignition ramp function of a heater (1) to be adapted to the tolerances of the gas stepping motor valve (31) and environmental variables, thereby ensuring increased functional reliability when the heater (1) is ignited.

Description

The invention relates to a method for operating a heater with an electronic gas-air compound, a computer program, a control device, a heater and a use of a heater.

Conventional gas burners usually control the gas/air ratio via a pneumatic gas/air ratio controller. By changing the fan speed, the amount of gas and thus also the output are changed at the same time. With an electronic gas-air combination, on the other hand, the pneumatic coupling of gas and air is eliminated. The power requested by the modulation controller of the heater is transferred in the burner control unit into a speed signal for the fan and at the same time into a command for the stepper motor on the gas valve. Since there is no reference for the actual air volume flow with this method, the exhaust gas quality must be monitored.

Electronic gas-air compound means that gas and air are supplied separately from each other. That is, the amount of gas follows the amount of air via a stepper motor gas valve. In the case of electronic gas-air systems, the combustion is monitored by an ionization electrode. By measuring the electrical conductivity of the flame, it is possible to assess the quality of the combustion. This is used to control the gas supply, mostly by means of an actuator designed as a gas stepping motor. One advantage over pneumatic gas-air systems is the ability to adapt to fluctuations in the gas composition.

During the ignition process of an electronic gas-air compound, a gas stepping motor valve is moved via a ramp control and an ignition device is actuated at the same time. The ionization current is measured as a signal from the flame via the ionization electrode. If there is no flame signal after a defined ignition safety time has elapsed, the ignition process is aborted.

However, it has been shown that various causes, such as component tolerances of the gas stepping motor valve, its state of wear or the gas composition during the ignition process, can lead to ignition in the limit range. These are often accompanied by severe deflagrations, which, in addition to unpleasant noises, can also cause damage to the heater.

the EP 3 301 365 A1 discloses a method for controlling an ignition operation of a heating system, it being possible to take into account an operating parameter detected before the ignition operation. The operating parameter is suitable for determining a quality of a fuel used in the heating system, or its calorific value, or a type of fuel and/or a power requirement for the heating system. A fluid supply parameter can be increased until an ignition value of the same is reached and a flame ignites in the heating system. The method is carried out as part of the commissioning or ignition process of a heating device and the problem of possible ignition in the border area with the associated potential for damage to the heating device therefore remains. The method also does not take into account possible component tolerances and/or the state of wear of connected components, such as the gas stepper motor in particular.

It is the object of the invention to provide a method for operating a heat generator with an electronic gas/air combination, which overcomes the stated problems of the prior art and enables a reliable and trouble-free ignition process.

In addition, the method should be able to be carried out as far as possible without additional components, so that the robustness of a proposed heating device is not reduced in comparison to the prior art.

These objects are solved by the features of the independent patent claims. Further advantageous refinements of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically meaningful manner and define further refinements of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred configurations of the invention being presented.

1. a) Verfahren einer Öffnungsposition eines Gasschrittmotorventils über eine Zündrampenfunktion;
2. b) Erfassen eines lonisationsstromes der Flamme des Heizgerätes;
3. c) Erfassen der Öffnungsposition des Gasschrittmotorventils bei Erreichen eines definierten Grenzwertes des lonisationsstromes;
4. d) Anpassen der Zündrampenfunktion zum Öffnen des Gasschrittmotorventils unter Einbeziehung der in Schritt c) erfassten Position des Gasschrittmotorventils.

The method proposed here for operating a heater with an electronic gas-air combination comprises at least the following steps to be carried out during heating operation:

1. a) moving an opening position of a gas stepping motor valve via an ignition ramp function;
2. b) detecting an ionization current of the flame of the heater;
3. c) detecting the opening position of the gas stepping motor valve when a defined limit value of the ionization current is reached;
4. d) Adjusting the ignition ramp function for opening the gas stepping motor valve, taking into account the position of the gas stepping motor valve detected in step c).

Steps a) - c) are carried out at least once at the same time. The method can also be carried out with a heating device that is also described here. A control unit of a heating device is preferably set up to carry out the proposed method.

In a step a), an opening position of a gas stepping motor valve is moved via an ignition ramp function. The gas stepping motor valve controls the gas supply via the opening position and thus the composition of the gas mixture (gas-air combination) to be supplied to the heat generator. The ignition ramp function is preferably a linear function and maps the opening position of the gas stepping motor valve for a defined period of time, in particular the ignition safety time.

At the same time step b) is carried out, a detection of the ionization current during the movement of the opening position of the gas stepping motor valve.

In addition, according to step c), the detected ionization current is compared with a defined limit value. When the defined limit value is reached, the opening position of the gas stepping motor valve is recorded. The heater can now return to normal heating operation. It is pointed out that the ignition safety time plays no role in the implementation of the method proposed here, but that the opening position of the gas stepping motor valve is moved according to the ignition ramp function until the defined limit value is reached.

In a step d), the ignition ramp function is adapted. The ignition ramp function can be characterized by a minimum opening position of the gas stepping motor valve, which causes a lean combustion mixture, for example with a lambda value of approx. 1.6, and a maximum opening position of the gas stepping motor valve, which causes a higher proportion of fuel in the combustion mixture, for example a lambda value of approx. 1 ,1. The gas stepping motor valve is often in the minimum opening position at the start of a defined period of time and in the maximum opening position at the end of a defined period of time, the ignition safety time.

The maximum opening position of the adapted ignition ramp function can be proportional to or preferably equal to the opening position of the gas stepping motor valve detected in step c) when the defined limit value is reached.

The minimum opening position of the ignition ramp function can be changed by the same amount in the opposite direction as the maximum opening position is adjusted. So if the maximum opening position of the adjusted ignition ramp function is lowered by Δx, the minimum opening position of the adjusted ignition ramp function can be increased by the same value Δx. The opening position in the middle of the defined time period is the same for original and adapted ignition ramp functions in this embodiment.

The defined limit value in step c) can be a value determined in advance, which ensures reliable ignition without deflagration.

In one embodiment of the method, it is determined at least during the implementation of steps a) to c) that the flame is going out or is beginning to go out. Based on this, processes for ending heating operation and then restarting heating operation can be (automatically) initiated.

In a preferred embodiment, the method proposed here is repeated regularly. It is seen as an advantage that the ignition ramp function can be continuously adapted to changing boundary conditions, for example wear of the gas stepping motor valve and/or a change in the composition of the fuel.

According to a further preferred embodiment, steps a) - c) are repeated several times and an average value of the opening position of the detected in step c). Gas stepper motor valve formed. The ignition ramp function according to step d) can then be adjusted using the mean value of the detected opening positions. An advantage of this embodiment is seen in increased procedural security due to a larger database.

According to a further aspect, a computer program is also proposed which is set up to (at least partially) carry out a method presented here. In other words, this relates in particular to a computer program (product), comprising instructions which, when the program is executed by a computer, cause the latter to execute a method described here.

According to a further aspect, a machine-readable storage medium is also proposed, on which the computer program is stored. The machine-readable storage medium can be a computer-readable data carrier.

According to a further aspect, a control unit for a heater is also proposed, set up to carry out a method presented here. For this purpose, the control unit can have a processor, for example, or have it at its disposal. In this context, the processor can, for example, execute the method stored in a memory (of the control unit). At least the ignition ramp function and/or the defined limit value are preferably stored in the same memory.

According to a further aspect, a heater with a control unit presented here is also proposed. The heating device is in particular a gas heating device with a gas burner and a gas delivery device which can deliver a mixture of gas and combustion air (electronic gas-air combination) to a gas burner.

According to a further aspect, the use of a heating device with an electronic gas/air combination for adapting an ignition ramp function of a gas stepping motor valve during heating operation is proposed.

A method for operating a heater with an electronic gas-air compound, a computer program, a control device and a heater for carrying out the method and a use of a heater are thus specified here, which at least partially solve the problems described with reference to the prior art. In particular, the method, the computer program, the control device and the heater as well as the use each at least contribute to ensuring a reliable ignition process of the heater. In addition, the proposed method is technically easy to implement, since no additional technical means are required.

In particular, in the method proposed here, an ignition ramp function is adapted during heating operation, so that a permanent (continuous or intermittent) adaptation of the ignition ramp function to changes in the gas mixture (or its calorific value) and possible changes in components involved in mixture formation, in particular the gas stepping motor valve , can be done. The ignition ramp function can be limited to a predefined limit value of the ionization current of the flame, with the predefined limit value of the ionization current being able to characterize a borderline combustion air ratio (lambda value) that should not be fallen below during an ignition process in order to avoid critical ignition processes.

The invention and the technical environment will now be explained in detail with reference to the figures. It should be noted that the figures are schematic in nature and are not intended to limit the invention.

Fig. 1:

einen Ablauf eines hier vorgeschlagen Verfahrens,

Fig. 2:

eine Regelkurve eines Heizgerätes,

Fig. 3:

eine Darstellung einer Anpassung der Zündrampenfunktion gemäß dem vorgeschlagenen Verfahren, und

Fig. 4:

ein hier vorgeschlagenes Heizgerät.

They represent:

Figure 1:

a sequence of a method proposed here,

Figure 2:

a control curve of a heater,

Figure 3:

a representation of an adaptation of the ignition ramp function according to the proposed method, and

Figure 4:

a heater proposed here.

1 shows an exemplary and schematic sequence of a method proposed here. The method allows an ignition ramp function of a heater that is in heating mode to be adapted. The method steps a) to d) are represented as blocks 110, 120, 130 and 140.

In block 110, according to step a), an opening position of a gas stepping motor valve is moved via an original ignition ramp function Z ₀ (t).

At the same time as block 110, the ionization current I _ion is detected in block 120 according to step b).

In block 130, analogously to blocks 110 and 120 according to step c), the opening position of the gas stepping motor valve is detected when a predefined limit value of the ionization current I _ion is reached.

In block 140, according to step d), the ignition ramp function Z(t) is adjusted, taking into account the opening position of the gas stepping motor valve detected in block 130 when a predefined limit value of the ionization current I _ion is reached and an adjusted ignition ramp function Z is defined

2 shows a control curve Rλn as a function of the ionization current I _Ion depending on a fan speed n _G . The control curve Rλn represents a nominal λ value of burner operation, for example a lambda value λ=1.3. The fan speed n _G is an example of an operating parameter of a gas delivery device of the heater.

At an ignition speed nz of the fan, points Pmin and Pmax can be defined. The point Pmin corresponds to an ionization current I _ion with the minimum opening position of the gas stepping motor valve and thus a maximum lambda value, for example λ=1.6 for the ignition ramp function Z(t). The point Pmax correspondingly defines an ionization current I _ion at the maximum opening position of the gas stepping motor valve and thus a minimum lambda value, for example λ=1.1, for the ignition ramp function Z(t). In this context, the defined limit value of the ionization current can be determined.

3 shows a diagram in which the opening position of the gas stepping motor valve during an ignition process is shown as a function of time t. A point in time tz defines the end of the ignition process, the ignition safety time. The Z ₀ (t) function represented an original ignition ramp function that had not yet been adjusted for gas stepping motor valve tolerances and environmental variables. Point Z _D represents the opening position of the gas stepping motor valve detected in block 130 when a predefined limit value of the ionization current is reached at time tz. The original ignition ramp function Z ₀ (t) can now be adapted by an adapted ignition ramp function Z _A (t) assuming the value Z _D at time tz. The change value Δx is defined by the difference between the original ignition ramp function Z ₀ (t) at time tz and the opening position of the gas stepping motor valve detected in block 130 when the predefined limit value Z _D of the ionization current I _ion is reached. A further adaptation can consist in the fact that the adapted ignition function Z _A (t) leads through a point Z ₀ (0)+Δx at t=0.

4 shows an example of a heater 1 proposed here, having a heat generator 11. Leading to the heat generator 11 is an air intake duct 2 in which a gas delivery device 21 is arranged, which is embodied here as a blower. The speed of the blower is a measure of the heat output of the heater 1. In a gas supply 3, a gas stepping motor valve 31 is arranged. An ionization electrode 41 is positioned in the heat generator 11 in the area of a flame 4, by means of which an ionization current I _ion of the flame 4 can be measured. An ignition device 42 is also arranged in the area of the flame 4 and is set up to ignite the flame 4 during an ignition process.

A control unit 5 is electrically connected to at least the ionization electrode 41, the gas stepping motor valve 31 and the blower. Control unit 5 is set up to carry out a method proposed here.

To carry out the proposed method, at least one ignition ramp function Z ₀ (t) and a defined limit value of the ionization current I _ion are stored in a memory in control unit 5 .

The method allows an ignition ramp function of a heater to be adapted to the tolerances of the gas stepping motor valve and environmental variables, thereby ensuring increased functional reliability when the heater is ignited.

reference list

1

heater

11

heat generator

2

air intake duct

21

gas conveying device

3

gas supply

31

gas stepper motor valve

4

flame

41

ionization electrode

42

ignition device

5

control unit

Claims (8)

Method for operating a heater (1) with an electronic gas-air compound, comprising at least the following steps to be carried out during heating operation: a) moving an opening position of a gas stepping motor valve (31) via an ignition ramp function; b) detecting the ionization current of a flame (4); c) detecting the opening position of the gas stepping motor valve (31) when a defined limit value of the ionization current is reached; d) Adaptation of the ignition ramp function, taking into account the position of the gas stepping motor valve (31) detected in step c) when a defined limit value of the ionization current is reached. Method according to the preceding claim, wherein when adapting the ignition ramp function in step d), the position of the gas stepping motor valve (31) detected in step c) defines the maximum opening position of the adapted ignition ramp function. Method according to one of the preceding claims, wherein the method is repeated at defined time intervals. Computer program set up to carry out a method according to one of the preceding claims. Machine-readable storage medium on which the computer program according to claim 4 is stored. Control unit (5) for a heater (1) set up to carry out a method according to one of Claims 1 to 3. Heating device (1) having a control unit (5) according to Claim 6. Use of a heater (1) with an electronic gas-air combination for adjusting an ignition ramp function of a gas stepping motor valve (31) during heating operation.

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