EP2218967B1 - Method and device for regulating the running time of a burner - Google Patents

Description

The invention relates to a method and a device for regulating the running time of a burner, which is suitable for supplying heat to a boiler, hereinafter referred to as heat.

In particular, the invention relates to a method for controlling the life of a burner, which is suitable, a thermal medium, for. As water or oil to supply heat in a boiler or heat storage to increase the temperature of the thermal storage medium in the boiler by supplying heat, based on the specification of a boiler temperature setpoint T _SOLL .

Background of the invention

Such burners are known in the art, for. As gas or oil burners in heating systems and are e.g. as a sole heat generator or as a heat generator from a plurality of heat generators, e.g. used in bivalent heating systems.

Furthermore, gas and oil burners are known in the prior art which can be controlled in a mode in which an output burner power P _Br can be continuously modulated to give a predetermined, determined or set burner power value P _Br and thus equal or close the boiler temperature to keep the setpoint T _SOLL . However, in such controlled gas and oil burners, the output power P _{Br may} not be continuously down-modulated down to zero, so that the burner is controlled by clocking (burner cycles) when a heat demand, for example, depending on a building load below a minimum burner capacity of Brenners occurs.

In this case, the burner is switched on at a boiler temperature below the setpoint T _SOLL to increase the boiler temperature above the setpoint T _SOLL . If the boiler temperature is above the setpoint T _SOLL , the burner is switched off again. By the Brenner clocks, will thus alternately supply and shut down, the boiler temperature can be maintained near the setpoint T _set, even if the burner capacity required for this purpose is below the minimum burner power or the minimum modulated burner power.

As a method for controlling such a gas or oil burner, the so-called two-step control method with hysteresis is known in the prior art. In the two-point control method, a control deviation ΔT of the boiler temperature from the boiler temperature setpoint T _{SOLL is} determined by subtraction of the boiler temperature setpoint T _SOLL with a currently determined boiler temperature, the so-called boiler temperature actual value T _IST : $$\mathrm{.DELTA.T}={\mathrm{T}}_{\mathrm{SHOULD}}\square {\mathrm{T}}_{\mathrm{IS}}\mathrm{,}$$

If a control deviation ΔT greater than zero is determined here, the boiler temperature is below the setpoint T _SOLL and otherwise, with a determined ΔT less than zero, the boiler temperature is currently above the setpoint T _SOLL .

According to the two-step control method with hysteresis, a so-called turn-on difference value and a so-called turn-off difference value are set. If it is now determined that the control deviation is greater than the specified switch-on difference, the burner is switched on, since the boiler temperature is then more than the specified switch-on difference below the setpoint T _SOLL . When the burner is switched on, the boiler temperature is then increased by supplying heat to the boiler until it can be determined that the absolute value of the control deviation reaches or exceeds the specified switch-off difference (the switch-off difference is defined as positive). Then the burner is switched off again. This cycle is executed repeatedly so that the boiler temperature value fluctuates by cyclically switching the burner on and off by the setpoint T _SOLL .

Very short burner run times between burner startup and shutdown often occur in the two-point controller method described above, even if relatively high turn-on and turn-off differential values are set. The burner run times in a control according to the two-point control method can sometimes be less than 1 minute. However, since the burner may only have to be switched on again after a short time, and thus possibly has a short period duration, many switching cycles result in the two-point control method, which may in some cases comprise more than 100 switching on and off operations of the burner per day.

Furthermore, a high dynamic loading of the boiler due to rapid increase in temperature and subsequent rapid drop in temperature with a short period and high number of switching cycles per day.

Furthermore occur in the short cycle times or periods, or in the high number of cycles per day by frequent switching on and off of the burner more problems. So z. B. poor emission levels of the burner, a reduced efficiency and increased wear.

Additionally, in oil burners, heavy soiling of a heat exchanger by soot may occur due to poor emission levels.

Fig. 1 shows the actual boiler temperature T _IST as a function of the time t of a boiler, the heat is temporarily supplied by a burner, the burner is controlled by the known in the art two-step control method with hysteresis. Additionally shows Fig. 1 the time course of the burner power P _Br according to the boiler temperature actual value T _{IST shown} as a function of time t.

After the two-point control method with hysteresis, a boiler temperature setpoint T _{SOLL is} set and a switch-off or switch-on difference is set. The switch-off difference results from the difference between a specified temperature maximum value T _MAX and the boiler temperature setpoint T _SOLL . The switch-off difference results from the difference between the boiler temperature setpoint T _SOLL and a set minimum temperature value T _MIN . In the course of time, the current boiler temperature actual value T _{IST is} determined in each case in order to determine a control deviation between the boiler temperature actual value T _IST and the boiler temperature target value T _SOLL .

When the burner is switched on, heat is supplied to the boiler and the boiler temperature or the boiler temperature actual value T _IST increases over time. If it is determined that the boiler temperature actual value T _IST rises above the set maximum temperature value T _MAX , the burner is switched off. In other words, if the determined control deviation between the actual boiler temperature T _IST and the boiler temperature setpoint T _SOLL in absolute value increases above the setpoint above the switch-off difference for boiler temperatures, the burner is switched off. As a result, the boiler temperature drops until it first drops below the setpoint T _SOLL and then below the set minimum temperature value T _MIN .

If it is determined that the boiler temperature actual value T _{IST has} fallen below the minimum temperature T _MIN , ie in other words the control deviation below the setpoint exceeds the set switch-on difference, the burner is switched on again so that heat is supplied to the boiler and the boiler temperature again increases.

As in Fig. 1 Thus, the two-point controller method leads to a cyclic switching on and off of the burner, whereby the boiler temperature varies by the set target value T _SOLL . The respective on and off times of the burner are in Fig. 1 represented by the dashed vertical lines. In the lower part of the Fig. 1 the burner power P _{Br is shown} as a function of time. In a period between switching off the burner and turning on the burner again, the burner power P _{Br is} equal to zero (or at a low standby value).

If the burner is turned on at a certain time, the burner power P _{Br increases} to a high burner starting power and is then modulated down to a lower value. This leads to a rapid rise in temperature in the boiler due to the high burner start-up power, which eventually drops again before it rises continuously due to a burner power P _Br below the high burner start-up performance.

However, it may happen that the high temperature rise due to the high burner start-up performance without much delay above the set temperature maximum value T _MAX , which is turned off again in the two-point controller method with hysteresis of the burner. This can result in a very short burner time in which the boiler is dynamically stressed by the rapid temperature fluctuations and high temperature amplitudes, and in addition, this can lead to combustion with high emissions. Such premature burner shutdown by a temperature overshoot due to the high burner starting power is in Fig. 1 shown in the second cycle.

In order to avoid the problems of the two-way controller method described above, it is known in the art to select high turn-on and turn-off differential values, e.g. B. a switch-on difference of 6 K (Kelvin) and a switch-off of about 8 K. This allows the cycle times of the burner can be extended, and the number of cycles per day can be reduced. However, according to this method, the further problem arises that the amplitudes of the temperature fluctuation of the boiler temperature increase by the desired value T _SOLL at high switch-on and switch-off difference values. This may possibly lead to a limited utilization capacity of the burner. So it is known that high switching on and off are unsuitable for a variety of heating systems, eg. B. Low-temperature floor heating systems in which the boiler directly, so without mixer, to a heating circuit, eg. B. the underfloor heating, is connected.

With the above-mentioned example values for the switch-on difference (6 K) and the switch-off difference (8 K), a boiler setpoint temperature of approx. B. 26 ° C a cycle in which a burner is switched on only when the boiler temperature falls below 20 ° C, and continue the burner is switched off again when the boiler temperature is 34 ° C. This leads to the problem that a building only completely cools down before the burner starts again. After that, when the burner is running, however, the building is overheated. With a period that can take several days in practice, this means that a living temperature in the building is one day too cold and one day too warm.

Furthermore, the prior art control methods for controlling a burner are known in which the two-point controller method is extended such that in addition a variable minimum pause time, z. 4 minutes, is set or set. In addition to the switch-on criterion for the burner based on the comparison of the control deviation with the specified switch-on differential value, it is then checked whether the specified minimum pause time has elapsed since the last switch-off of the burner.

As a result, the cycle times of the burner can be increased or the number of cycles per day can be reduced. However, such a method can cause the boiler temperature to drop too much if the boiler temperature deviation falls below the set switch-on difference before the minimum pause time has elapsed.

DE 34 26 937 C1 describes a device for determining the on and off periods of a burner which heats a heat exchanger of a hot water heating system. The heat exchanger is in series with a circulation pump and parallel to an overflow line. A temperature sensor measures the measuring temperature of the water leaving the heat exchanger. An integrator is supplied with the difference between a reference temperature and the measured temperature measured by the temperature sensor. A hysteresis switch causes the burner to be turned on when the integration value reaches one threshold of the hysteresis switch, and the burner is turned off when the integration value reaches the other limit.

DE 196 49 157 A1 describes a device for heating control with a burner which heats a heating medium, resulting in a time course of an actual temperature, which depends on the heating power, the thermal behavior of the system and the building to be heated. A controller operates the burner via a switch, the switching time being dependent on a measure of an area which is influenced by the time profile of the actual temperature.

DE 33 30 990 A1 describes a method for regulating boiler systems when setting a target output temperature and comparing the actual output temperature as a control variable Integration of the formed control difference for controlling a burner, wherein the integration of the control difference is made digital.

Summary of the invention

An object of the present invention is to avoid the disadvantages and problems of the known control methods of a burner and to optimize a runtime control of a burner.

In particular, it is a further object of the invention to avoid the above-described disadvantages and problems of the known two-step controller method with hysteresis and the extended two-point controller method with an additional minimum break time of the burner.

Another object of the invention is to provide a method and apparatus for controlling a burner capable of supplying heat to a boiler to enable a lower number of cycles of the burner per day, and the problems of frequent turning on and off of the burner, such as. B. to avoid increased emissions, a reduced efficiency and increased wear.

To solve the above-described objects of the invention, a method for controlling the running time of a burner according to claim 1 and an apparatus for controlling the running time of a burner according to claim 7 is proposed. Preferred embodiments are described in the dependent claims.

• Einstellen eines Kesseltemperatur-Sollwerts T_SOLL, der einen Sollwert der Kesseltemperatur angibt,
• Zuführen von Wärme durch den Brenner zu dem Kessel,
• kontinuierliches oder wiederholtes Ermitteln eines momentanen Kesseltemperatur-Istwerts T_IST, der von einer momentanen Temperatur in zumindest einem Teil des Kesselvolumens abhängt, zum Bestimmen des Kesseltemperatur-Istwerts T_IST(t) als Funktion der Zeit t, und
• kontinuierliches oder wiederholtes Bestimmen einer momentanen Regelabweichungsdifferenz ΔT, die eine Differenz zwischen dem eingestellten Kesseltemperatur-Sollwert T_SOLL und dem bestimmten momentanen Kesseltemperatur-Istwert T_IST angibt, zum Bestimmen der Regelabweichungsdifferenz ΔT(t) als Funktion der Zeit t.

The method according to the invention for controlling the running time of a burner suitable for supplying heat to a boiler comprises the following method steps:

• Setting a boiler temperature setpoint T _SOLL , which specifies a boiler temperature setpoint,
• Supplying heat through the burner to the boiler,
• continuously or repeatedly determining a current boiler temperature actual value T _actual , which depends on a current temperature in at least a part of the boiler volume, for determining the boiler temperature actual value T _actual (t) as a function of the time t, and
• continuously or repeatedly determining a current control deviation difference ΔT indicating a difference between the set boiler temperature setpoint T _SOLL and the determined current boiler temperature actual value T _IST , for determining the control deviation difference ΔT (t) as a function of the time t.

• Bestimmen eines Abschaltintegrals I_AB(t) durch Integralbildung in Abhängigkeit der Regelabweichungsdifferenz ΔT(t) über die Zeit t, wenn der Kesseltemperatur-Istwert T_IST größer ist als der Kesseltemperatur-Sollwert T_SOLL,
• Abschalten des Brenners zu einem ersten Zeitpunkt t₁, an dem der Wert I_AB(t₁) des Abschaltintegrals I_AB(t) einen ersten Schwellwert SW₁ erreicht, um das Zuführen von Wärme durch den Brenner zu beenden.

Furthermore, the method for regulating the running time of a burner according to the present invention comprises the method steps:

• Determining a switch-off integral I _AB (t) by integral formation as a function of the control deviation difference ΔT (t) over the time t when the boiler temperature actual value T _{IST is} greater than the boiler temperature setpoint T _SOLL ,
• Turning off the burner at a first time t ₁ , at which the value I _AB (t ₁ ) of the Abschaltintegrals I _AB (t) reaches a first threshold SW ₁ , to stop the supply of heat through the burner.

In contrast to the prior art, the inventive method described above for controlling a burner uses a new approach, in which the burner is not connected via rigid temperature limits, but via the determination of a connection integral by integral formation as a function of the determined control deviation, in particular over one Temperature parameter (as a function of time), which differs by a first constant temperature difference from the determined deviation error (as a function of time t), or on the determined deviation error (as a function of time t) itself.

The invention takes advantage of the fact that a lack of inertia on the generator side (heat generation) can be supplemented by inertia on the consumer side. Furthermore, the invention takes advantage of the fact that it is crucial for the comfort of a consumer, what amount of energy is fed, and what temperature level prevails, and not the actual instantaneous performance of the burner.

Furthermore, the inventive method allows longer cycle times and a lower number of cycles of the burner per day, since it is not regulated by means of rigid temperature limits. Thus, according to the invention, longer burner run times and break times result, whereby lower emission values, a higher energy saving and additionally a reduced maintenance requirement can be achieved. The invention thus offers over the prior art thus an optimized control of a burner with an optimized burner runtime.

• Bestimmen eines Zuschaltintegrals I_IU(t) durch Integralbildung in Abhängigkeit der Regelabweichungsdifferenz ΔT(t) über die Zeit t, wenn der Kesseltemperatur-Istwert T_IST kleiner ist als der Kesseltemperatur-Sollwert T_SOLL, und/oder
• Zuschalten des Brenners zu einem zweiten Zeitpunkt t₂, an dem der Wert I_ZU(t₂) des Zuschaltintegrals I_ZU(t) einen zweiten Schwellwert SW₂ erreicht, um dem Kessel Wärme durch den Brenner zuzuführen.

Furthermore, the method for regulating the running time of a burner according to the present invention comprises the further method steps:

• Determining a Zuschaltintegrals I _IU (t) by integral formation as a function of the control deviation difference .DELTA.T (t) over the time t when the boiler temperature actual value T _{IST is} smaller than the boiler temperature setpoint T _SOLL , and / or
• Connecting the burner at a second time t ₂ at which the value I _ZU (t ₂ ) of the Zuschaltintegrals I _ZU (t) reaches a second threshold SW ₂ to supply heat to the boiler through the burner.

As described above with respect to the turn-off integral, integral formation is carried out as a function of the determined control deviation, in particular via a temperature parameter (as a function of time), the temperature difference around the first constant temperature difference or a second constant temperature difference (as a function of the control deviation) Time t) deviates, or on the determined deviation error (as a function of time t) itself.

Thus, the runtime control can be further optimized by, in addition to the turning on of the burner, the subsequent shutdown of the burner in the Burner cycles based on an integral as a function of the control deviation .DELTA.T (t) over the time t is regulated and not based on rigid temperature limits. Furthermore, a further reduction in the number of cycles of the burner per day is made possible, when on and off integrals are determined for controlling the switching on and off of burner clocking. This results in even longer burner running and break times, which means that even lower emission values, even greater energy savings and, in addition, even lower maintenance costs can be achieved.

Preferably, in the method according to the invention, at least the steps of supplying heat, determining the cut-off integral, switching off the burner, determining a turn-on integral and switching on the burner are repeated cyclically.

This makes it possible to keep the boiler temperature value close to the set boiler temperature setpoint T _SOLL by cyclically switching the burner on and off.

Preferably, the first threshold value SW _{1 can} be set manually or under process control, and the method according to the invention preferably also comprises the step of setting the first threshold value SW ₁ .

This makes it possible for the first threshold value, that is to say the switch-off integral threshold value SW ₁ , to be parametrizable, for example to a desired or required system behavior.

Furthermore, in the method according to the invention, the cut-off integral I _AB (t) is determined by integration up to a third time t ₃ , at which the boiler temperature actual value T _ACT (t) reaches or falls below the boiler temperature setpoint T _SOLL after switching off the burner, and wherein the second threshold value SW _{2 is} preferably set according to the value I _AB (t ₃ ) of the turn-off integral I _AB (t) at the third time t ₃ , so that the second time t _{2 is} preferably the time at which the absolute value | _ZU (t) | of the integration integral I _ZU (t) the absolute values | I _AB (t ₃ ) | of the turn-off integral I _AB (t) reaches or exceeds at the third time t ₃ .

Thus, a dynamic Zuschaltintegralschwelle SW _{2 is} possible. The invention thus preferably makes use of the fact that the value of the turn-off integral at this time t _{3 is} a measure of the too much introduced energy since, after the burner was switched off after exceeding the first threshold SW ₁ , as long as further integrated until the boiler temperature is less than or equal to the setpoint.

Furthermore, the burner preferably remains switched off until a connection integral formed analogously to the previously determined switch-off integral achieves the same value as the previously determined switch-off integral. Thus, it is possible that at a standstill of the burner (when the burner is off) is undersupplied to the same extent as was oversupplied before. Thus, there is no over-supply or under-supply on a timely basis. The only short-term over- and under-supplies do not cause any loss of comfort, as these occur essentially only within a burner cycle and thus be compensated by the inertia of the entire system.

Preferably, the method according to the invention further comprises a method step of setting a control deviation limit ΔT _MAX , wherein the burner preferably reaches or exceeds a control deviation limit ΔT _MAX at the first time t ₁ or at a fourth time t ₄ at which the absolute value of the system deviation ΔT (t) reaches or exceeds a control deviation limit ΔT _MAX , is switched off before the first time t ₁ .

Thus, a high overshoot of the setpoint T _{SOLL can} be avoided by the burner is switched off when the control deviation exceeds the control deviation limit .DELTA.T _MAX . The amplitudes of the control deviation can then be additionally limited by temperature values. High temperature amplitudes can thus be avoided even if the switch-off integral has not yet reached or exceeded the first threshold value SW _1, for example due to a rapid increase in temperature, although a very high control deviation already exists. Thus, high temperature amplitudes can be avoided, for example in the case of a lack of volume flow of the thermal storage medium in a heating system.

Analogously, preferably in a further method step of the method, a second control deviation limit ΔT _{MAX; 2} can be set, so that the burner is not only switched on when the connection integral reaches the second threshold SW ₂ , but preferably also at a control deviation at which the boiler temperature Actual value T _{IST is below} the boiler temperature setpoint T _SOLL by more than ΔT _{MAX; 2} .

Preferably, the inventive method further comprises the step of defining a temperature range around the boiler temperature setpoint T _SOLL by setting a first temperature range value T ₁ that is greater than the boiler temperature setpoint T _SOLL , and a second temperature range value T ₂ , which is smaller than the boiler temperature setpoint T _SOLL , wherein the cut-off integral I _AB (T) is preferably determined only if the determined current boiler temperature actual value T _{IST is} greater than the first temperature range value T ₁ , and / or wherein the Zuschaltintegral I _ZU (t) is preferably determined only if the determined current boiler temperature actual value T _{IST is} smaller than the second temperature range value T ₂ .

Thus, to the boiler temperature set point T _set a so-called dead zone having a temperature width of z. B. 1 K defined (ie T ₁ □ T ₂ = 1 K), with neither a supply and a shutdown integral is formed when the control deviation .DELTA.T or the amplitudes of the control deviation .DELTA.T are so small that the boiler temperature actual value T _ACT lies within the dead zone or wavers. As long as T _{IST is} within the dead zone, the integration is preferably not performed, or preferably stopped. This prevents the burner from being switched on or off when the actual boiler temperature T _IST fluctuates only slightly, namely within the dead zone, by the boiler temperature setpoint T _SOLL . Thus, unnecessary turning on and off operations of the burner can be prevented.

Preferably, during the integration for the integral formation of the switch-off integral, a first temperature parameter is integrated as a function of the determined deviation which deviates from the determined control deviation by a first constant temperature difference, in particular preferably according to the difference between the first temperature range value T ₁ and the boiler temperature setpoint T _SOLL deviates, and preferably this is further integrated in the integration for the integral formation of the Zuschaltintegrals a second temperature parameter as a function of the determined deviation difference, the hysteresis difference from the determined deviation by a second constant temperature difference, in particular preferably according to the difference between the boiler temperature setpoint T _SOLL and the second temperature range value T ₂ , deviates.

Preferably, the method according to the invention further comprises the step of resetting the determined switch-off integral I _AB (t) to zero when the boiler temperature actual value T _IST falls below the boiler temperature setpoint T _SOLL when the burner is switched on.

In a control of the burner in the modulated mode (for. Example in winter), it may occur that the boiler temperature setpoint T _set optionally even below, if the burner supplies heat to the boiler. If the boiler temperature rises then slightly above the setpoint and falls back shortly thereafter, etc., if necessary, without accumulating the Abschaltintegrals to the value zero, an accumulation of these small deviations may cause a certain Abschaltintegral reaches the threshold SW ₁ , although turning off the burner is not recommended , Such a switching off of the burner can be avoided by resetting the cut-off integral to the value zero when the boiler temperature falls below the setpoint or the first temperature range parameter T ₁ when the burner is in operation.

In the following, the device according to the invention for regulating the running time of a burner which is suitable for supplying heat to a boiler is described, which is suitable for carrying out the method according to the invention. In this case, the advantages are not discussed in detail since they correspond to the advantages of the method.

• ein Kesseltemperatur-Sollwert-Einstellungsmittel zum Einstellen eines Kesseltemperatur-Sollwerts T_SOLL, der einen Sollwert der Kesseltemperatur angibt,
• ein Kesseltemperatur-Istwert-Ermittelungsmittel zum kontinuierlichen oder wiederholten Ermitteln eines momentanen Kesseltemperatur-Istwerts T_IST, der eine momentane Temperatur in zumindest einem Teil des Kesselvolumens angibt, zum Bestimmen des Kesseltemperatur-Istwerts T_IST(t) als Funktion der Zeit t,
• ein Regelabweichungs-Bestimmungsmittel zum kontinuierlichen oder wiederholten Bestimmen einer momentanen Regelabweichungsdifferenz ΔT, die eine Differenz zwischen dem eingestellten Kesseltemperatur-Sollwert T_SOLL und dem bestimmten momentanen Kesseltemperatur-Istwert T_IST angibt, zum Bestimmen der Regelabweichungsdifferenz ΔT(t) als Funktion der Zeit t, und/oder
• ein Brennersteuerungsmittel zum Zu- und Abschalten des Brenners.

A device according to the present invention for controlling the running time of a burner comprises:

• a boiler temperature target value setting means for setting a boiler temperature target value T _SOLL indicative of a set value of the boiler temperature,
• a boiler temperature actual value determining means for continuously or repeatedly determining a current boiler temperature actual value T _actual , which indicates a current temperature in at least a part of the boiler volume, for determining the boiler temperature actual value T _actual (t) as a function of the time t,
• a control deviation determining means for continuously or repeatedly determining a current control deviation difference ΔT indicating a difference between the set boiler temperature setpoint T _SOLL and the determined current boiler temperature actual value T _IST , for determining the control deviation difference ΔT (t) as a function of the time t, and or
• a burner control means for turning on and off the burner.

The device according to the invention is characterized in that it comprises a control deviation integral determining means for determining an integral by integral formation as a function of the control deviation ΔT (t) over the time t.

According to the invention, the control deviation integral determining means preferably determines a switch-off integral I _AB (t) when the boiler temperature actual value T _{IST is} greater than the boiler temperature target value T _SOLL . The burner is preferably turned off by the burner control means at a first time t ₁ at which the value I _AB (t ₁ ) of the turn-off integral I _AB (t) reaches a first threshold SW ₁ for supplying heat to finish by the burner. Furthermore, the control deviation integral determining means preferably determines a turn-on integral I _ZU (t) when the boiler temperature actual value T _{IST is} smaller than the boiler temperature target value T _SOLL , and the burner is preferably switched on by the burner control means at a second time t ₂ at which the value I _ZU (t ₂ ) of the connection integral I _ZU (t) reaches a second threshold value SW ₂ in order to supply heat to the boiler through the burner.

Preferably, the device according to the invention further comprises a threshold value setting means for setting the first threshold value SW ₁ .

Preferably, the control deviation integral determining means determines the cut-off integral I _AB (t) by integral formation as a function of the control deviation .DELTA.T (t) until a third time t ₃ at which the actual boiler temperature T _{IST reaches} the boiler temperature setpoint T _SOLL after switching off the burner or below, and preferably, the burner control means sets the second threshold SW ₂ corresponding to the value I _AB (t ₃ ) of the turn-off integral I _AB (t) at the third time t ₃ , so that the second time t _{2 is} preferably the time in that the absolute value of the turn-on integral I _ZU (t) reaches or exceeds the absolute value of the turn-off integral I _AB (t) at the third time t ₃ .

Preferably, the apparatus for controlling the running time of a burner further comprises a control deviation limit setting means for setting a control deviation limit ΔT _MAX , the burner preferably at the first time t ₁ or at a fourth time t ₄ , at which the absolute value of the control deviation difference .DELTA.T (t) reaches or exceeds a control deviation threshold ΔT _MAX before the first time t _{1 is turned off} by the burner control means.

Preferably, the control deviation limit setting means is further adapted to set a second control deviation limit ΔT _{MAX; 2} so that the burner can be switched on analogously when the control deviation difference ΔT (t) reaches or exceeds a control deviation threshold ΔT _{MAX; 2} before the injection integral becomes the second threshold SW ₂ reached.

Preferably, the device according to the invention further comprises a temperature range defining means for defining a temperature range around the boiler temperature setpoint T _SOLL by setting a first temperature range value T ₁ , which is preferably greater than the boiler temperature setpoint T _SOLL , and a second temperature range value T ₂ , preferably less than the boiler temperature setpoint T _SOLL , wherein the cut-off integral I _AB (t) is preferably determined by the control deviation integral determining means only when the determined current boiler temperature actual value T _{IST is} greater than the first temperature range T ₁ , and the Zuschaltintegral I _ZU (t) preferably only then determined by the control deviation integral determining means when the determined instantaneous boiler temperature actual value T _{IST is} smaller than the second temperature range value T ₂ .

Preferably, during the integration for the integral formation of the switch-off integral, a first temperature parameter is integrated as a function of the determined deviation which deviates from the determined control deviation by a first constant temperature difference, in particular preferably according to the difference between the first temperature range value T ₁ and the boiler temperature setpoint T _SOLL deviates, and preferably this is further integrated in the integration for the integral formation of the Zuschaltintegrals a second temperature parameter as a function of the determined deviation difference, the hysteresis difference from the determined deviation by a second constant temperature difference, in particular preferably according to the difference between the boiler temperature setpoint T _SOLL and the second temperature range value T ₂ , deviates.

Preferably, the apparatus of the invention further comprises an integral reset means for resetting an integral determined by the error integral integral determining means to zero, the integral resetting means resetting the determined disable integral I _AB (t) to zero, preferably, when the actual temperature of the boiler T is _below the boiler temperature setpoint T _SOLL with the burner switched on. The integral reset means may preferably also be suitable for resetting the determined switch-off integral I _AB (t) to zero when the boiler temperature actual value T _{IST falls} below the first temperature range value T ₁ when the burner is switched on.

Brief description of the figures

• Fig. 1 shows a profile of a boiler temperature actual value T _IST as a function of time t after the known in the prior art two-step control method with hysteresis and the associated curve of the burner power P _Br as a function of time t.
• Fig. 2 shows a schematic representation of the burner, the boiler and the apparatus for controlling the burner according to an embodiment of the present invention.
• Fig. 3A and Fig. 3B show a flowchart of a method for controlling a burner according to a first embodiment of the present invention.
• Fig. 4A . Fig. 4B and Fig. 4C show a flowchart of a method for controlling a burner according to a second embodiment of the present invention.
• Fig. 5 shows a curve of a boiler temperature actual value T _IST as a function of time t according to a second embodiment of the present invention and the associated curve of the burner power P _Br as a function of time t.
• Fig. 6 shows a section of a diagram according to a third embodiment of the present invention and the associated course of the burner power P _Br as a function of time t.
• Fig. 7 shows a schematic representation of an embodiment of the apparatus for controlling a burner according to the present invention.

Detailed description of the figures and preferred embodiments of the invention

In the following, the present invention will be described in detail with reference to embodiments of the method for controlling a burner according to the present invention, and an embodiment of an apparatus for controlling a burner according to the present invention with reference to the figures.

Fig. 2 shows a burner 10, a boiler 20 and a device 30 for controlling the burner 10, in a schematic representation. The burner 10 is adapted to a thermal storage medium, for. As water or oil to supply heat in the boiler 20, wherein the burner 10 is controlled by the device 30 for controlling a burner 10.

The kettle 20 is in this case e.g. an independent boiler, z. As a water boiler, or a to a heating system z. B. a building connected boiler. The burner 10 may be e.g. to trade a gas or oil burner. However, a control method according to the invention is not limited to the regulation of gas or oil burners, and may generally be applied to any device capable of being switched on and off to temporarily supply heat to a boiler.

Fig. 3 shows a flowchart of a method for controlling a burner according to a first embodiment of the present invention. The method includes the steps S31 Adjust kettle temperature set point T _set, S32 connection of the torch 10, S33 supplying heat, S34 determining the boiler temperature actual value _T (t), S35 determining the deviation difference .DELTA.T (t), S36 determining the Abschaltintegrals I _AB (t), S37 Turning off the burner 10, and S38 determining the Zuschaltintegrals I _ZU (t).

In step S31 setting the boiler temperature target value T _SOLL , a set value of the boiler temperature is set, based on which the control of the burner 10 is executed according to the control method of the present invention. The following describes the method for controlling a burner 10 based on a one-time setting of the boiler temperature setpoint T _SOLL . However, the present invention is not limited to the one-time setting of the boiler temperature target value T _SOLL . Depending on requirements, a new boiler temperature setpoint T _{SOLL can be} set.

In step S32 connecting the burner 10, the switched-off burner 10 is switched on in order to supply heat to the boiler 20 in step S33.

Further, S34 determining the actual value of the boiler temperature _T (t) is determined the boiler temperature as a function of time t in step. For this purpose, a current boiler temperature, or the instantaneous boiler temperature actual value T _IST , either continuously or repeatedly or periodically determined. By continuously determining the boiler temperature, the actual boiler temperature T _IST can be determined directly as a function of the time t. If the boiler temperature actual value T _{IST is} repeated or periodically z. B. always determined after the expiration of a set time interval .DELTA.t, the boiler temperature actual value T _{IS is determined} as a step function of the time t. The boiler temperature actual value T _IST is in this case determined such that an integral formation by integration of the boiler temperature actual value T _IST with the time t is possible.

wodurch die Regelabweichungsdifferenz ΔT(t) als Funktion der Zeit t anhand des Kesseltemperatur-Istwerts T_IST(t) als Funktion der Zeit t und dem Kesseltemperatur-Sollwert T_SOLL gebildet werden kann: $$\mathrm{\Delta T}\left(\mathrm{t}\right)={\mathrm{T}}_{\mathrm{SOLL}}\square {\mathrm{T}}_{\mathrm{IST}}\left(\mathrm{t}\right)\mathrm{.}$$

In step S35 determining the control deviation difference ΔT (t), the control deviation difference between the actual boiler temperature T _IST and the boiler temperature setpoint T _{SOLL is} determined: $$\mathrm{.DELTA.T}={\mathrm{T}}_{\mathrm{SHOULD}}\square {\mathrm{T}}_{\mathrm{IS}}.$$

whereby the control deviation difference ΔT (t) can be formed as a function of the time t on the basis of the _actual boiler temperature T _IST (t) as a function of the time t and the boiler temperature setpoint T _SOLL : $$\mathrm{.DELTA.T}\left(\mathrm{t}\right)={\mathrm{T}}_{\mathrm{SHOULD}}\square {\mathrm{T}}_{\mathrm{IS}}\left(\mathrm{t}\right)\mathrm{,}$$

By supplying heat, the boiler temperature actual value rises above the boiler temperature setpoint T _SOLL at a time τo. Is now determined that the actual boiler temperature exceeds the boiler temperature set value in step S36, determining the Abschaltintegrals I _AB (t) is a Abschaltintegral I _AB (t) is determined: $$I_{\mathit{FROM}}\left(t\right)=\underset{{\tau }_0}{\overset{t}{\int }}\left|\mathrm{\Delta }T\right|\mathit{d\tau }$$

If the boiler temperature actual value T _{IST is determined} periodically after each time interval Δt, the switch-off integral can be determined as the sum of the determined values (step function values) multiplied by Δt (determination of an area below a step function).

The switch-off integral I _AB (t) is thus determined by integration of the control deviation ΔT (t) over the time t when the actual boiler temperature T _{IST is} above the boiler temperature setpoint T _SOLL . Since in the definition of the control deviation difference .DELTA.T above above the nominal temperature T of the _boiler, a _desired value is set negative value is determined, wherein determining the Abschaltintegrals I _AB (t) is the absolute value of the deviation difference .DELTA.T (t) is determined to determine a positive Abschaltintegral I _AB (t). However, the present invention is not limited to this determination of the turn-off integral I _AB (t) and can also be determined without absolute value formation, possibly by simultaneously adapting the signs of threshold values.

At a time t ₁ , the determined switch-off integral I _AB (t), which is also a function of the time t, rises to a set first threshold value SW ₁ , so that according to the invention it is ascertained that the burner 10 is to be switched off at the time t ₁ , since the certain cut-off integral I _AB at this time t ₁ has reached or exceeds the threshold SW ₁ . In contrast to the two-point control method with hysteresis described above, the burner 10 is thus not switched off when the boiler temperature actual value T _IST exceeds a maximum value T _MAX , but when the particular turn-off integral I _AB , determined by integration of the control deviation difference .DELTA.T, reaches a threshold SW ₁ or exceeds.

According to the invention, at time t _1, in step S37, switching off the burner causes the heat supply of the burner 10 to the boiler 20 to be ended by switching off the burner 10. This is followed by the boiler temperature, since the boiler 20 no heat is supplied through the burner 10 more.

If the boiler temperature at a time T ₀ 'below the set boiler temperature set point T _set is integrated again over the control error .DELTA.T to the step S38 of determining Zuschaltintegrals I _TO (t) to form a Zuschaltintegral. Since the control deviation .DELTA.T is positive at boiler temperatures below the boiler temperature target value T _SOLL according to the above definition, absolute value formation is dispensed with in the inventive determination of the turn-on integral I _ZU according to the first exemplary embodiment of the invention: $$I_{\mathit{TO}}\left(t\right)=\underset{{\tau }_0\text{'}}{\overset{t}{\int }}\mathrm{\Delta }\mathit{T\; d}$$

However, it may be necessary to perform absolute value formation if there is another definition of the control deviation ΔT or the threshold values (eg negative threshold values).

As long as the boiler temperature is below the boiler temperature setpoint T _SOLL , the determined value of the Zuschaltintegrals I _ZU (t) increases and reaches a second at a time t ₂ Threshold SW ₂ . If it is determined that the connection integral I _ZU (t) reaches or exceeds the second threshold value SW ₂ , the burner is switched on again in step S 32, switching on the burner in order to re-supply heat to the boiler 20. In the presently described embodiment of the method for controlling a burner 10 in FIG Fig. 3 the steps S32 to S38 are repeated cyclically, so that the burner is switched on cyclically when the particular turn-on integral I _ZU (t) reaches or exceeds the second threshold SW ₂ , to be switched off, respectively, when the determined turn-off integral I _AB (t) reaches or exceeds the first threshold SW ₁ .

A preferred second embodiment of the method for controlling a burner 10 according to the present invention is shown in the flowchart in FIG Fig. 4 shown. According to the preferred second embodiment of the method according to the present invention, the method comprises the steps S401 setting the boiler temperature setpoint T _SOLL , S402 setting the first threshold SW ₁ , S403 defining the temperature range (dead zone), S404 setting the control deviation limit ΔT _MAX , S405 Switching on the burner, S406 Supplying heat, S407 Determining the boiler temperature actual value T _IST (t), S408 Determining the control deviation difference ΔT (t), S409 Determining the switch-off integral I _AB (t), S410 Switching off the burner 10, S411 Determining the switch-off integral I _AB (t), and S412 determining the turn-on integral I _ZU (t).

In step S401, setting of the boiler temperature target value T _SOLL is made in analogy with step S31 in FIG Fig. 3 set a boiler temperature setpoint T _SOLL .

In step S402 setting of the first threshold value SW ₁ , a first threshold value SW _{1 is} set, which analogously to the exemplary embodiment in FIG Fig. 3 represents a threshold value for the turn-off integral I _AB (t) in order to indicate from which value of the turn-off integral I _AB (t) the burner 10 is to be switched off according to the invention.

In step S403, defining the temperature range (dead zone), a temperature range around the set boiler temperature setpoint T _{SOLL is} defined by setting a first temperature range value T ₁ greater than the boiler temperature setpoint T _SOLL and setting a second temperature range value T ₂ less than the set boiler temperature setpoint T _SHOULD . Herein, the step S403 defining the temperature range, or the so-called dead zone, may be performed by individually setting the first and second temperature range values T ₁ and T ₂ , or by setting a half width of the dead zone so that the first temperature range value T ₁ and the second Temperature range value T ₂ each lie around the half-value of the dead zone above or below the set boiler temperature setpoint T _SOLL .

In step S404, setting of the control deviation limit value ΔT _MAX , a maximum control deviation limit value ΔT _{MAX is} set in order to limit large temperature amplitudes or large temperature fluctuations of the boiler temperature by the boiler temperature setpoint T _{SOLL, in} addition to limiting the closing and closing integrals, additionally by absolute temperature values.

This means that the burner 10 may be switched on or off if the control deviation ΔT exceeds the set control deviation limit value ΔT _MAX , although a specific switch-on integral has not yet reached the first or the second threshold value. Optionally, two different control deviation limits can be set to limit a control deviation above and / or below the threshold independently of each other.

Furthermore, the method according to the second embodiment of the present invention, as in Fig. 3 Further, steps S405 of connecting the burner and S406 supplying heat analogously to steps S32 and S33 in FIG Fig. 3 ,

Analogous to the steps S34 and S35 in FIG Fig. 3 includes the method in Fig. 4 furthermore, steps S407 determine the boiler temperature actual value T _IST (t) and S408 determine the control deviation difference ΔT (t). Both the boiler temperature actual value T _IST and the control deviation difference ΔT are analogous to the method in Fig. 3 determined as a function of time t.

By supplying heat, the boiler temperature first exceeds the boiler temperature setpoint T _SOLL and, shortly thereafter, the first temperature range value T ₁ , so that the control deviation difference ΔT becomes smaller than the difference T _SOLL □ T ₁ . At this time τ _AB , the determination of the turn-off integral I _AB (t) begins in step S409, determining the turn-off integral I _AB (t). In contrast to the previously described embodiment of the method according to Fig. 3 in which the switch-off integral I _AB (t) was determined from a time τ ₀ at which the boiler temperature exceeds the boiler temperature setpoint T _SOLL , the switch-off integral I _AB (t) is determined from a time τ _AB in this exemplary embodiment of the method, at which the boiler temperature leaves the defined temperature range, or the dead zone, by the boiler temperature setpoint T _SOLL : $$I_{\mathit{FROM}}\left(t\right)=\underset{{\tau }_{\mathit{FROM}}}{\overset{t}{\int }}\left[\left|\mathrm{\Delta }T\left(\tau \right)\right|-\left(T_1-T_{\mathit{SHOULD}}\right)\right]\mathit{d\tau }$$

Furthermore, in the integration in this embodiment, as can be seen from the formula given above, a surface area below the time profile of the boiler temperature actual value T _{IST is formed} up to the first temperature range value T ₁ , so that an area between the temperature range value T ₁ and the boiler temperature setpoint T _SOLL remains unconsidered. However, the present invention is not limited to such integral formation, and it is possible to provide embodiments of the invention in which integral formation is performed over the entire control deviation .DELTA.T, wherein the integral formation only begins at a time at which the boiler temperature actual value T _IST defined temperature range or the dead zone leaves.

As long as the boiler temperature, or the actual boiler temperature T _IST , remains above the first temperature range value T ₁ , the value of the switch-off integral I _AB (t) is determined.

In step S410 of turning off the burner 10, the burner 10 is turned off when the value of the cut-off integral I _AB (t) reaches or exceeds the set first threshold SW ₁ , or if previously the absolute value of the control deviation ΔT exceeds the set maximum value for the control deviation ΔT _MAX reaches or exceeds. By switching off the burner, a heat supply from the burner 10 to the boiler 20 is changed, so that the boiler temperature begins to decrease.

Even if the burner is off, the shutdown integral I _AB (t) is still determined in step S411 after switching off the burner. In this case, the switch-off integral I _AB (t) is determined at least until a point in time at which the decreasing boiler temperature reaches or falls below the first temperature range value T ₁ . Finally, the switch-off integral I _AB (t) is further determined until a time t ₃ at which the boiler temperature actual value T _IST reaches or falls below the first temperature range value T ₁ . At this time, the determination of the turn-off integral I _AB (t) is terminated and the previously determined value I _AB (t ₃ ) is set as the new value for the second threshold SW ₂ : $${\mathrm{I}}_{\mathrm{FROM}}\left({\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="imgf0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{3}}\right)={\mathrm{<figure-callout\; id="2"\; label="SW"\; filenames="imgf0008.png"\; state="\{\{state\}\}">SW</figure-callout>}}_{\mathrm{2}}\mathrm{,}$$

If the boiler temperature continues, so that the control deviation difference .DELTA.T τ greater than or equal to the difference of boiler temperature setpoint temperature T _set with the second temperature range value T ₂ at a time point _TO is the integration begins in step S412 determining the Zuschaltintegrals I _TO (t) for determining the Connection integral I _ZU (t): $$I_{\mathit{TO}}\left(t\right)=\underset{{\tau }_{\mathit{TO}}}{\overset{t}{\int }}\left[\mathrm{\Delta }T\left(\tau \right)-\left(T_{\mathit{SHOULD}}-T_2\right))\right]\mathit{d\tau }$$

If the specific connection integral I _ZU (t) reaches or falls below the second threshold value SW ₂ , which is set according to the value of the turn-off integral I _AB (t ₃ ) at the time t ₃ , the burner is switched on again in step S405 in order to start the boiler 20 in FIG Heat is returned to step S406. Furthermore, the burner 10 is switched on by an extended control even if the control deviation .DELTA.T reaches or exceeds a maximum control deviation .DELTA.T _MAX with decreasing boiler temperature actual value below the setpoint, although the particular switch integral I _ZU (t) the second threshold SW ₂ = I _AB (t ₃ ) has not yet reached.

The steps S405 to S412 are repeated cyclically, so that the boiler temperature actual value T _IST fluctuates around the boiler temperature setpoint T _SOLL .

By setting the second threshold SW ₂ = I _AB (t ₃ ), it can be ensured that the boiler is undersupplied within a cycle to the same extent as it was directly over-supplied with thermal energy. The reason for this is that the turn-off integral from the time τ _AB to the time t ₁ substantially corresponds to the value of the excess heat energy introduced, and it is ensured that the burner remains turned off within the cycle until an analog integral Zuschaltintegral the same value achieved as the previously formed Abschaltintegral, which essentially corresponds to an oversupply of heat energy. Within one cycle, this ensures that the boiler is neither over- nor undersupplied.

Fig. 5 FIG. 12 shows a cycle of a burner, which according to the method for controlling a burner after the in Fig. 4 described second embodiment of the present invention is regulated. Fig. 5 shows the temperature profile of the boiler temperature as a function of time t and the corresponding time course of the burner power P _Br as a function of time t. The set setpoint T _SOLL for the boiler temperature is represented by a horizontal line. Above and below the set target value T _SOLL are two more horizontal Lines are shown, which define the dead zone or the defined temperature range around the boiler temperature setpoint T _SOLL and represent the first and second temperature range values T ₁ and T ₂ . In addition, another horizontal line represents the set maximum control deviation ΔT _MAX .

At a time t ₀ , the burner 10 is switched on, represented by the increase of the burner power at the time t ₀ (S405). The boiler temperature rises due to the connection of the burner 10 and reaches or exceeds the boiler temperature setpoint T _SOLL and shortly thereafter at a time τ _AB the first temperature range value T ₁ . At this time τ _AB , the determination of the turn-off integral I _AB (t) starts in step S409. At a time t ₁ , the determined value of the cut-off integral I _AB (t) reaches the set first threshold value SW ₁ , so that the burner is switched off at this time t ₁ , represented by the decrease in the burner power P _Br at the time t ₁ (S410). ,

The Abschaltintegral I _AB (t) will now be further determined in step S411 until the actual boiler temperature _T, at a time t ₃ reaches the first temperature range T ₁ value and below. The hatched area below the course of the boiler temperature as a function of the time t between the times τ _AB and t ₃ corresponds to the value of the turn-off integral I _AB (t ₃ ) at the time t ₃ . This value is set as the new second threshold value SW ₂ for the next addition integral I _ZU (t) to be determined.

After the time t ₃ , the boiler temperature continues to fall when the burner 10 is switched off until shortly thereafter it falls below the defined dead zone, ie below the first temperature range value T ₂ . At this time τ _ZU , the determination of the ON integral I _ZU (t) starts in step S412.

At a time t ₂ , the value of the connection integral I _ZU (t ₂ ) reaches the second threshold value SW ₂ = I _AB (t ₃ ), so that the burner 10 is switched on again at the time t ₂ in step S405. Off and Zuschaltintegralwerte that have been determined so far, and / or the second threshold SW ₂ are reset, so that another burner cycle can be done again by the control method according to the present invention according to the second embodiment.

Fig. 6 illustrates the operation of the set control deviation maximum value Δ T _MAX . The boiler temperature rises after switching on the burner 10 at a time t ₀ . At a time t ₂ , the boiler temperature exceeds the first temperature range value T ₁ and the determination of the switch-off integral I _AB (t) begins. The control deviation increases Connecting the burner 10 so fast that the boiler temperature T _actual at a time t _{4 reaches} a value at which the absolute value of the determined instantaneous control deviation .DELTA.T (t ₄ ) reaches the set control deviation maximum value .DELTA.T _MAX .

According to the second embodiment of the method for controlling a burner according to the present invention, the burner is turned off at this time t ₄ , although the value of the turn-off integral I _AB (t ₄ ) at this time t ₄ has not yet reached or exceeded the first threshold SW ₁ Has.

Thus, even in the inventive method in which the switching on and off of the burner is determined by determining Ab- and Zuschaltintegralen, too high temperature amplitudes with rapid increase or drop in the boiler temperature can be avoided by limiting the control deviation in addition to the specific control deviation integrals is, ie at a very high excess of the boiler temperature setpoint T _SOLL the burner is also switched off, possibly independent of the particular shutdown integral.

Furthermore, in the control method of a burner according to the second embodiment of the present invention, a temperature range, or a dead zone (eg, 1 K) is defined, with no turn-on integrals formed within the dead zone. Within this dead zone the integration is stopped.

In a further embodiment of the method for controlling a burner according to the present invention, the value of the cut-off integral I _AB (t) is additionally reset even if the boiler temperature actual value T _IST falls below the boiler temperature setpoint T _SOLL when the burner is in operation. In this case, the Abschaltintegral is reset to the value zero, or the time at which the boiler temperature actual value T _IST exceeds the boiler temperature setpoint T _SOLL again used as a new starting time for the determination of the Abschaltintegrals I _AB (t).

Thus, it can be avoided that a long-running burner is switched off in a modulating operation by accumulating small control deviations. In the case of modulating operation, a small fluctuation in the boiler temperature within the defined dead zone may also occur, in which, according to the second embodiment of the present invention, no turn-off and turn-on integrals are also formed. Thus, with small deviations within the dead zone, no cumulation occurs in the determination of the ab- or Zuschaltintegrale on, so that small deviations within the dead zone can not lead to unnecessary or undesirable switching on and off of the burner 10.

Fig. 7 shows an apparatus for controlling a burner according to an embodiment of the present invention, which is adapted to perform at least one of the inventive method according to the above-described embodiments of the present invention. The apparatus 30 for controlling a burner 10 according to an embodiment of the present invention comprises a boiler temperature target value setting means 31, a boiler temperature actual value determining means 32, a control deviation determining means 33, a burner control means 34, a control deviation integral determining means 35, a threshold value Adjustment means 36, a deviation control limit setting means 37, and a temperature range defining means 38.

The boiler temperature target value setting means 31 is adapted to set a target value for the boiler temperature, that is, the above-described boiler temperature target value T _SOLL for the control of the burner 10.

The boiler temperature actual value determining means 32 is suitable for determining the instantaneous value of the boiler temperature, that is to say the boiler temperature actual value T _ACT, in at least one part of the boiler. The boiler temperature actual value determining means 32 comprises for this purpose at least one means for measuring the boiler temperature in a region of the boiler or a plurality of means for determining boiler temperatures at different points of the boiler, the boiler temperature actual value determining means 32 being optionally suitable for determine and further process boiler temperature values determined by the multiplicity of means, if appropriate by weighted or unweighted averaging, in order to determine an actual value T _IST .

Furthermore, the boiler temperature actual value determining means 32 is adapted to determine the actual value of the boiler temperature continuously or repeatedly or periodically. Thus, the boiler temperature T _IST can be determined as a function of time t.

The control deviation determining means 33 is suitable for determining a control deviation ΔT between the set boiler temperature setpoint T _SOLL and the currently determined boiler temperature actual value T _IST . For this purpose, the control deviation determining means 33 is at least suitable for determining a difference ΔT = T _SOLL □ T _IST .

The control deviation integral determining means 35 is adapted to integrate the control deviations ΔT (t) continuously or repeatedly determined by the control deviation determining means 33 over the time t, to determine integrals as a function of the control deviation and / or the absolute value of a specific integral over time t form.

The burner control means 34 is adapted to turn on and off the burner 10 based on the determined turn-on and turn-on integrals determined by the control deviation integral determining means 35.

The temperature range defining means 38 is adapted to define a temperature range, or a dead zone, to define the set boiler temperature setpoint T _SOLL . The temperature range defining means 38 is adapted to set a first temperature range value T ₁ greater than the boiler temperature target value T _SOLL and a second temperature range value T ₂ smaller than the boiler temperature target value T _SOLL or to define a temperature range around the boiler temperature target value T _SOLL by setting a Temperature range half width, which defines half the width of the temperature range to be defined, wherein the boiler temperature setpoint T _{SOLL is} in the center of the defined temperature range.

The threshold value setting means 36 is adapted to set a first threshold value SW ₁ and / or a second threshold value SW ₂ as threshold values for the determined turn-on and turn-on integrals determined by the control deviation integral determining means 35. The burner control means 34 is suitable for switching off the burner 10 when a certain switch-off integral I _AB (t) reaches or exceeds the first threshold value SW ₁ , and to switch off the burner 10 when a switch-on integral I _ZU (t) determined by the control deviation integral determining means 35 reaches or exceeds the second threshold SW ₂ .

The control deviation threshold setting means 37 is adapted to set a maximum value for the control deviation as the control deviation threshold ΔT _MAX , so that large temperature amplitudes can be avoided by the burner control means 34 turning off the burner when the control deviation determined by the control deviation determining means 33 ΔT or the absolute value thereof reaches the set control deviation threshold ΔT _MAX before a turn-on integral determined by the control deviation integral determining means 35 reaches or exceeds a predetermined threshold value.

Finally, the apparatus 30 for controlling a burner 10 further comprises integral reset means 39, which is adapted to reset an integral determined by the control deviation integral determining means 35 to the value zero when the actual boiler temperature T _{IST falls} within the defined temperature range Zone) penetrates, in particular, when the boiler temperature actual value T _ACT falls back to the defined temperature range when the burner is switched on.

By the above-described embodiments of the method of controlling a burner 10 according to the present invention and the described preferred embodiment of a device for controlling a burner 10 according to the present invention, a significant optimization of the control of a burner is enabled when the burner is below a minimum modulatable burner output is clocked. This allows a significant increase in the burner run times, which dynamic loads due to temperature fluctuations of the boiler can be avoided and a low-emission combustion in the burner is possible.

By setting the second threshold SW ₂ on the basis of the determined switch-off integral I _AB (t) until a time at which the boiler temperature falls below the set setpoint T _SOLL with the burner switched off, it is possible that the boiler or a heating system connected to the boiler for a building is undersupplied at a standstill of the burner to the same extent as was oversupplied in the same cycle. On average over-supply or under-supply of heat energy is thus avoided.

According to the invention, a control method of a burner is thus provided in which further loss of comfort for a user is avoided. The over-supply or under-supply occurring only briefly within one cycle can be compensated by the inertia on the consumer side.

Furthermore, it is possible that a desired behavior (long run times or low temperature amplitudes desired) can be easily set via a single parameter (eg the first threshold SW ₁ ) when the second threshold value SW ₂ for the turn-on integral is determined on the basis of the previously determined turn-off integral.

The method according to the invention is suitable both for gas burners and for oil burners, as well as for other burner types which are clocked for loads below a minimum modulatable burner output. The method is suitable for heating systems for all building types and design temperatures and offers a high level of robustness due to the integral approach, according to which the burner shutdown and connection times are determined in a cycle not on the basis of rigid temperature limits, but on the basis of an integral of the control deviation over time t.

Claims (11)

1. A method for controlling the runtime of a burner (10) which is adapted to feed heat to a boiler (20), wherein said method comprises the method steps:

   - adjusting (S31; S401) a boiler temperature target value T_SOLL, indicating a target value of the boiler temperature,

   - feeding (S33; S406) heat through said burner (10) to said boiler (20),

   - continuously or repeatedly detecting (S34; S407) an instantaneous boiler temperature actual value T_IST depending on an instantaneous temperature at least in a part of the boiler volume in order to determine the boiler temperature actual value T_IST(t) as a function of time t,

   - continuously or repeatedly determining (S35; S408) an instantaneous control deviation difference ΔT which is a difference between said adjusted boiler temperature target value T_SOLL and said determined instantaneous boiler temperature actual value T_IST in order to determine the control deviation difference ΔT(t) as a function of time t,

   - determining (S36; S409, S411) a turn-off integral I_AB(t) by calculating an integral depending on said control deviation difference ΔT(t) over time t if the boiler temperature actual value T_IST is larger than the boiler temperature target value T_SOLL,

   - turning-off (S37; S410) said burner (10) at a first point of time t₁, at which the value I_AB(t₁) of said turn-off integral I_AB(t) reaches a first threshold value SW₁ in order to stop feeding heat to said burner (10),

   - determining (S38; S412) a turn-on integral Izu(t) by calculating an integral depending on said control deviation difference ΔT(t) over time t if said boiler temperature actual value T_IST is smaller than said boiler temperature target value T_SOLL,

   - turning-on (S32; S405) said burner (10) at a second point of time t₂ at which the value I_ZU(t₂) of said turn-on integral Izu(t) reaches a second threshold value SW₂ in order to feed heat through said burner (10) to said boiler (20),

   characterized in that said turn-off integral I_AB(t) is determined up to a third point of time t₃ at which the boiler temperature actual value T_IST(t) reaches or deceeds the boiler temperature target value T_SOLL or a predetermined first temperature range value T₁ after turning off said burner (10), wherein said second threshold value SW₂ is set in accordance with the value I_AB(t₃) of said turn-off integral I_AB(t) at the third point of time t₃ at which the absolute value |I_ZU(t)| of said turn-on integral Izu(t) reaches or exceeds the absolute value |I_AB(t)| of said turn-off integral I_AB(t) at the third point of time t₃.
2. The method according to claim 1, characterized by repeatedly performing the steps of feeding (S33; S406) heat, determining (S36; S409, S411) said turn-off integral I_AB(t), turning-off (S37; S410) said burner (10), determining (S38; S412) a turn-on integral Izu(t) and turning-on (S32; S405) said burner (10).
3. The method according to claim 1 or 2, characterized by the further method step of adjusting (S402) said first threshold value SW₁.
4. The method according to at least one of the claims 1 to 3, characterized by that method step of adjusting (S404) a control deviation limit value ΔT_MAX,
   wherein said burner (10) is turned off before said first point of time t₁ at the point of time t₁ or at a fourth point of time t₄ at which the absolute value |ΔT(t₄)| of said control deviation difference ΔT(t) reaches or exceeds a control deviation limit value ΔT_MAX.
5. The method according to at least one of the claims 1 to 4, characterized by the method step of defining (S403) a temperature range around said boiler temperature target value T_SOLL by adjusting a first temperature range value T₁ which is larger than said boiler temperature target value T_SOLL and a second temperature range value T₂ which is smaller than said boiler temperature target value T_SOLL,
   wherein said turn-off integral I_AB(t) is determined only if the determined instantaneous boiler temperature actual value T_IST is larger than that first temperature range value T₁, and
   wherein said turn-on integral Izu(t) is determined only if the determined instantaneous boiler temperature actual value T_IST is smaller than that second temperature range value T₂.
6. The method according to at least one of the claims 1 to 5, characterized by the further method step of resetting said determined turn-off integral I_AB(t) to the value zero if the boiler temperature actual value T_IST deceeds the boiler temperature target value T_SOLL while said burner (10) is turned on.
7. An apparatus for controlling the runtime of burner (10) which is adapted to feed heat to a boiler (20), comprising:

   - a boiler temperature target value adjusting means (31) for adjusting a boiler temperature target value T_SOLL indicating a target value of the boiler temperature,

   - a boiler temperature actual value detecting means (32) for continuously or repeatedly detecting an instantaneous boiler temperature actual value T_IST which is an instantaneous temperature at least in a part of the boiler volume in order to determine the boiler temperature actual value T_IST(t) as a function of time t,

   - a control deviation determining means (33) for continuously or repeatedly determining an instantaneous control deviation difference ΔT which indicates the difference between the adjusted boiler temperature target value T_SOLL and said determined instantaneous boiler temperature actual value T_IST in order to determine the control deviation difference ΔT(t) as a function of time t,

   - a burner control means (34) for turning on and off said burner (10),

   - a control deviation integral determining means (35) for determining an integral by calculating an integral depending on said control deviation ΔT(t) over time t,

   wherein said control deviation integral determining means (35) determines a turn-off integral if the boiler temperature actual value T_IST is larger than the boiler temperature target value T_SOLL,
   said burner control means (34) turns off said burner (10) to a first point of time t₁ at which the value I_AB(t₁) of said turn-off integral I_AB(t) reaches a first threshold value SW₁ in order to stop feeding heat to said burner (10),
   said control deviation integral determining means (35) determines a turn-on integral Izu(t) if the boiler temperature actual value T_IST is smaller than the boiler temperature target value T_SOLL, and
   said burner control means (34) turns on said burner (10) to a second point of time t₂ at which the value I_ZU(t₂) of said turn-on integral Izu(t) reaches the second threshold value SW₂ in order to feed heat through said burner (10) to said boiler (20),
   characterized in that
   said control deviation integral determining means (35) determines said turn-off integral I_AB(t) by integrating up to a third point of time t₃ at which the boiler temperature actual value T_IST reaches or deceeds said boiler temperature target value T_SOLL or a first temperature range value T₁ after turning off said burner (10), and
   said burner control means (34) sets said second threshold value SW₂ in accordance with the value I_AB(t₃) of said turn-off integral I_AB(t) at the third point of time t₃ such that the second point of time t2 is the point of time at which the absolute value |I_ZU(t)| of said turn-on integral Izu(t) reaches or exceeds the absolute value |I_AB(t)| of said turn-off integral I_AB(t) at the third point of time t₃.
8. The apparatus according to claim 7, characterized by a threshold value adjusting means (36) for adjusting said first threshold value SW₁.
9. The apparatus according to claim 7 or 8 characterized by
   control deviation limit value adjusting means (37) for adjusting a control deviation limit value ΔT_MAX,
   wherein said burner (10) is turned off before said first point of time t₁ by said burner control means (34) at the first point of time t₁ or at a fourth point of time t₄ at which the absolute value |ΔT(t₄)| of said control deviation difference ΔT(t) reaches or exceeds a control deviation limit value ΔT_MAX.
10. The apparatus according to at least one of the claims 7 to 9, characterized by
    a temperature range defining means (38) for defining a temperature range around said boiler temperature target value T_SOLL by adjusting a first temperature range value T₁ which is larger than said boiler temperature target value T_SOLL and a second temperature range value T₂ which is smaller than said boiler temperature target value T_SOLL,
    wherein said turn-off integral I_AB(t) is determined by said control deviation integral determining means (35) only if the determined instantaneous boiler temperature actual value T_IST is smaller than the second temperature range value T₂.
11. The apparatus according to at least one of the claims 7 to 10, characterized by
    an integral resetting means (39) for resetting an integral determined by said control deviation integral determining means (35) to the value zero,
    wherein said integral resetting means (39) resets said determined turn-off integral I_AB(t) to the value zero if the boiler temperature actual value T_IST deceeds said boiler temperature target value T_SOLL while said burner (10) is turned on.

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