Continuously Modulating Actuator In A Combustion Apparatus

This application claims priority to EP Application No. 24175597.4 filed May 14, 2024, the contents of which are hereby incorporated by reference in their entirety.

The present disclosure relates to combustion. Various embodiments of the teachings herein include closed-loop control of flows of a fluid in a combustion apparatus, e.g., a continuous closed-loop control of flows of fluids such as air and/or fuel gas.

Changes in air temperature and/or air pressure cause fluctuations of the air/fuel ratio λ to occur in a combustion apparatus. Speed sensors and air pressure switches for measuring the air supply can come into consideration in a combustion apparatus. Speed sensors are not sensitive to fluctuations in air temperature and air pressure. Air pressure switches are only precise for monitoring air pressure at a specific pressure. Despite this, by using a number of switches, air pressure can be monitored at a number of pressures.

As a result of the said fluctuations during operation of a combustion apparatus at least one actuator of the combustion apparatus is to be readjusted during operation. The at least one actuator of the combustion apparatus can in this case be an air actuator or can comprise an air actuator. The air actuator acts on an air supply through an air supply channel of the combustion apparatus, wherein the air supply channel leads to a combustion chamber of the combustion apparatus. In particular the at least one actuator of the combustion apparatus can be a fan for air or comprise such a fan. The at least one actuator of the combustion apparatus can further be an air flap or comprise such an air flap.

Moreover, the at least one actuator of the combustion apparatus can be a fuel actuator or can comprise a fuel actuator. The fuel actuator acts on a fuel supply through a fuel supply channel of the combustion apparatus, wherein the fuel supply channel likewise leads to the combustion chamber of the combustion apparatus. In particular the at least one actuator of the combustion apparatus can be a valve for fuel gas or can comprise such a valve.

The re-adjustment of such actuators during operation has previously required intermediate stops. This means that the actuator is moved step-by-step. For example the air supply can be changed with the aid of a fan by a small amount. After a step-by-step change the change in the re-adjustment of the actuator stops. First of all the setting and/or the speed of the actuator is detected and compared to an end value. If the result of the comparison with the end value is that the end position of the actuator and/or the end speed of the actuator is yet to be reached, step-by-step re-adjustment is undertaken once again.

The step-by-step re-adjustment of the at least one actuator brings frequent starts and stops of the actuator with it. As a result of the frequent starts and stops the at least one actuator heats up and the mechanical wear on the at least one actuator increases. Moreover, the step-by-step re-adjustment with its frequent starts and stops is associated with undesired noise emissions.

As a result of the frequent starts and stops the energy required for the re-adjustment also increases. What is more, with a step-by-step re-adjustment, the at least one actuator requires more time to reach its end position and/or its end speed. Actually the additional time required before reaching the end position and/or the end speed would be able to be compensated for by an actuator with more mechanical power. Meanwhile the electrical power consumption of the at least one actuator increases with increasing mechanical power. The at least one actuator tends to heat up more with increasing electrical and/or mechanical power. This in turn would entail constructive measures for restricting the heating up of the at least one actuator.

European patent EP1236957B1 discloses a pressure sensor/air mass sensor, which is arranged in the air supply or exhaust gas outlet of a heating facility. A closed-loop controller, starting from the signal of the sensor, controls a fan. To reconcile the air volume flow at that moment with a required air volume flow a characteristic operating curve is stored. The air volume flow at that moment is constantly re-adjusted to the required air volume flow. Meanwhile a constant re-adjustment as in EP1236957B1 can be undertaken step-by-step in the known way.

European patent application EP2556303A2 discloses a venturi nozzle that creates a vacuum, with a mass flow sensor in an additional channel. An open-loop control or closed-loop control regulates the speed of a fan depending on a signal of the sensor to a required value. In this case, during operation of the fan, a signal obtained from the sensor is sent with the aid of a signal line to the open-loop control or closed-loop control. In this the operational open-loop control or closed-loop control of the fan from EP2556303A2 can be undertaken step-by-step.

German patent DE102004055715B4 deals with the setting of the air/fuel ratio of a firing facility. In accordance with DE102004055715B4 an air mass flow mis set to an increased value so that hygienic combustion occurs. In this case the air mass flow mcorresponding to hygienic combustion is set by changing a valve actuator speed of the fan. In this the change of the valve actuator speed of the fan from EP2556303A2 can be undertaken step-by-step.

A European patent application EP3676860A1 deals with a diagnostic apparatus and a method for magnetic valves. No reference to combustion apparatuses is established in patent application EP3676860A1. In accordance with EP3676860A1 a malfunction at a magnetic valve is detected with the aid of an analysis of the course of the flow. To do this, a measured flow course is compared with a reference flow course. An electrical resistance of a coil of the magnetic valve during operation is further recorded and is compared with a limit value. In the event of the resistance exceeding a predetermined value it is concluded that there is a fault.

A further patent application JP2006250203A discloses a closed-loop control and/or open-loop control for a valve with a coil. No reference to combustion apparatuses is established in patent application JP2006250203A. In accordance with JP2006250203A the current through the coil of the valve and also the recorded voltage is observed. From this an impedance of the coil during operation is calculated. Subsequently a working cycle based on the observed and calculated values is corrected.

The teachings of the present disclosure provide an improvement in the closed-loop control and/or open-loop control of actuators in a combustion apparatus. In particular it involves as far as possible a predictive closed-loop control and/or open-loop control of actuators in a combustion apparatus. In the case of a necessary reversal of direction braking operations are to be minimized.

For example, some embodiments of the teachings herein include a combustion apparatus comprising a burner () and at least one supply channel (,) in fluid communication with the burner (), the combustion apparatus comprising at least one actuator (,,-), which acts on a supply (,) of a fluid through the at least one supply channel (,) to the burner (), and a closed-loop control and/or open-loop control and/or supervision facility (), which is different from the at least one actuator (,,-) and communicatively couples with the at least one actuator (,,-), wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to: generate a first change signal from a first end value and to send the first change signal to the at least one actuator (,,-); generate a second change signal from a second end value and to send the second change signal to the at least one actuator (,,-); wherein the at least one actuator (,,-) comprises a processing unit and is configured: receive the first and the second change signal; determine a first change speed with the aid of the processing unit, based on the first and the second change signal; and begin a first change of a speed or of a position of the at least one actuator (,,-) using the first change speed.

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility () comprises a memory with a first plurality of part changes and is configured to: load the first plurality of part changes from the memory; and determine the first end value based on the first plurality of part changes.

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility () comprises a memory with a second plurality of part changes and is configured to: load the second plurality of part changes from the memory; and determine the second end value based on the first and/or the second plurality of part changes.

In some embodiments, the first end value is equal to the second end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to generate the second change signal, which is equal to the first change signal, from the second end value and to send the second change signal to the at least one actuator (,,-).

In some embodiments, the first end value is different from the second end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to generate the second change signal, which is different from the first change signal, from the second end value and to send the second change signal to the at least one actuator (,,-).

In some embodiments, the combustion apparatus comprises at least one sensor () and the at least one actuator (,,-) communicatively couples with the at least one sensor (), wherein the at least one actuator (,,-) is configured to: receive a first sensor signal from the at least one sensor (); determine with the aid of the processing unit from the first sensor signal a first actual variable selected from a first actual speed of the at least one actuator () or a first actual position of the at least one actuator (,-); and determine the first change speed with the aid of the processing unit, based on the first and the second change signal and the first actual variable.

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility () is configured to: generate a third change signal from a third end value and to send the third change signal to the at least one actuator (,,-); wherein the at least one actuator (,,-) is configured to: receive the third change signal; determine the first change speed with the aid of the processing unit, based on the first and the second and the third change signal; and begin the first change of a speed or of a position of the at least one actuator (,,-) using the first change speed.

In some embodiments, a third plurality of part changes is stored in the memory of the closed-loop control and/or open-loop control and/or supervision facility () and the closed-loop control and/or open-loop control and/or supervision facility () is configured to: load the third plurality of part changes from the memory; and determine the third end value based on the third plurality of part changes.

In some embodiments, the second end value is equal to the third end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to generate the third change signal, which is the same as the second change signal, from the third end value and to send the third change signal to the at least one actuator (,,-).

In some embodiments, the second end value is different from the third end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to generate the third change signal, which is different from the second change signal, from the third end value and to send the third change signal to the at least one actuator (,,-).

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility () is configured to: generate a fourth change signal from a fourth end value and to send the fourth change signal to the at least one actuator (,,-); wherein the at least one actuator (,,-) is configured: receive the fourth change signal during the first change; determine a second change speed with the aid of the processing unit, based on the second and/or the fourth change signal; and begin a second change of the speed or the position of the at least one actuator (,,-) using the second change speed.

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility () comprises a memory with a fourth plurality of part changes and is configured to: load the fourth plurality of part changes from the memory; and determine the fourth end value based on the fourth plurality of part changes.

In some embodiments, the second end value is the same as the fourth end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to: generate the fourth change signal, which is the same as the second change signal, from the fourth end value and to send the fourth change signal to the at least one actuator (,,-); wherein the at least one actuator (,,-) is configured: determine the second change speed with the aid of the processing unit, based on the second and the fourth change signal, wherein the second change speed is zero; and begin the second change of the speed or of the position of the at least one actuator (,,-) using the second change speed.

In some embodiments, the second end value is different from the fourth end value and wherein the closed-loop control and/or open-loop control and/or supervision facility () is configured to: generate the fourth change signal, which is different from the second change signal, from the fourth end value and to send the fourth change signal to the at least one actuator (,,-).

As another example, some embodiments include a method for closed-loop control and/or open-loop control of a combustion apparatus, the combustion apparatus comprising a burner () and at least one supply channel (,) in fluid communication with the burner (), the combustion apparatus comprising at least one actuator (,,-), which acts on a supply (,) of a fluid through the at least one supply channel (,) to the burner (), and a closed-loop control and/or open-loop control and/or supervision facility (), which is different from the at least one actuator (,,-) and communicatively couples with the at least one actuator (,,-), the method comprising: generating a first change signal from a first end value and sending of the first change signal to the at least one actuator (,,-); generating a second change signal from a second end value and sending of the second change signal to the at least one actuator (,,-); receipt of the first and of the second change signal by the at least one actuator (,,-); determination of a first change speed based on the first and the second change signal by the at least one actuator (,,-); and beginning a first change of a speed or of a position of the at least one actuator (,,-) using the first change speed.

The present disclosure thus teaches combustion apparatuses comprising at least one actuator and one closed-loop control and/or open-loop control and/or supervision facility. The at least one actuator acts on a supply of a fluid such as for example air or fuel gas through a supply channel of the combustion apparatus. The supply channel opens out into the burner of the same combustion apparatus.

A first change signal is now sent to the at least one actuator by the closed-loop control and/or open-loop control and/or supervision facility. The first change signal contains a first change, for example a first change of a speed of a fan or a change of a valve setting. A second change signal to the at least one actuator is further sent by the closed-loop control and/or open-loop control and/or supervision facility. The second change signal contains a second change, for example a second change of a speed of a fan or a change of a valve setting.

The at least one actuator receives the first change signal and the second change signal. The at least one actuator establishes a first change speed from the first and the second change signal. Finally, the at least one actuator begins an implementation of the change while taking into account the first change speed.

Thus a closed-loop control and/or open-loop control of the at least one actuator can receive a first change signal corresponding to a first change and a second change signal corresponding to a second change. The closed-loop control and/or open-loop control may be a processing unit and is local. The local open-loop control and/or closed-loop control establishes from the first change signal a first end speed and/or a first end position. The local open-loop control and/or closed-loop control establishes from the second change signal a second end speed and/or a second end position. The closed-loop control and/or open-loop control of the at least one actuator then establishes a speed of the first change, in order, on reaching the first end speed, to arrive seamlessly at the second end speed. Likewise a speed of the first change can be established, in order, on reaching the first end position, to arrive seamlessly at the second end position.

The aforementioned linkage of the first and second changes is able to be expanded to further changes.

In addition, the closed-loop control and/or open-loop control of the at least one actuator can assess whether a deviation between a required speed and an actual speed is lasting too long. Likewise the closed-loop control and/or open-loop control of the at least one actuator can assess whether a deviation between a required position and an actual position is lasting too long. In such a case the local closed-loop control and/or open-loop control of the at least one actuator can generate an error signal. The error signal is sent to a higher-ranking closed-loop control and/or open-loop control and/or supervision facility. The higher-ranking closed-loop control and/or open-loop control and/or supervision facility receives the error signal and where necessary sends a close command to at least one fuel actuator of the combustion apparatus.

What is more the closed-loop control and/or open-loop control and/or supervision facility of the combustion apparatus can assess whether a deviation between a required speed and an actual speed is lasting too long. Likewise the closed-loop control and/or open-loop control and/or supervision facility of the combustion apparatus can assess whether a deviation between a required position and an actual position is lasting too long. In such a case the closed-loop control and/or open-loop control and/or supervision facility of the combustion apparatus can generate an error signal. The closed-loop control and/or open-loop control and/or supervision facility of the combustion apparatus where necessary sends a close command to at least one fuel actuator of the combustion apparatus.

The change in the speed and/or the valve setting can be made up of a number of part changes. In some embodiments, the closed-loop control and/or open-loop control and/or supervision facility concatenates individual part changes from a plurality of part changes and thus makes uninterrupted operation possible.

During the implementation of the first change the closed-loop control and/or open-loop control and/or supervision facility can receive one or more signals from the at least one sensor. The at least one sensor can for example be a speed sensor of a fan and/or a valve setting sensor and/or a position sensor. In particular the at least one sensor can be part of the at least one actuator. The at least one sensor can also be in the supply channel of the combustion apparatus and record a flow of the fluid.

What is more a closed-loop control and/or open-loop control of the at least one actuator can assess whether the at least one actuator has already reached its end position and/or end speed. The closed-loop control and/or open-loop control may be local and is undertaken with the aid of the one or more signals. Provided the at least one actuator has not reached its end speed and/or end position and is away from its end speed and/or end position by a band, the change is continued. If on the other hand the at least one actuator is within the band around its end speed and/or end position, the change can be braked.

Before the end of the change the closed-loop control and/or open-loop control and/or supervision facility can check whether there is provision for a further change. When both changes point in the same direction, the change can be continued beyond the end speed and/or end position up to a further end speed or further end position. Thus an interruption is avoided.

Likewise, before the end of the change, the at least one actuator can check whether there is provision for a further change. For example the at least one actuator can receive a further command for a further (fourth) change from the closed-loop control and/or open-loop control and/or supervision facility. That further command is then present at an input interface and/or at a receive buffer of the at least one actuator. When both changes point in the same direction the change can be continued beyond the end speed and/or end position up to a further end speed or further end position. Thus the at least one actuator avoids an interruption at the closed-loop control and/or open-loop control and/or supervision facility. The load on the closed-loop control and/or open-loop control and/or supervision facility is thus relieved.

shows an example system incorporating teachings of the present disclosure and comprising a burner, a heat consumer, a fanwith adjustable speed and a motor-adjustable flap. The motor-adjustable flapis arranged after the air inlet. The heat consumer(heat exchanger) can for example be a hot water boiler. The air supplycan be set in accordance withby the motor-adjustable flapwith the aid of the signal lineand/or by specifying the speed of the fanwith the aid of the signal line.

If this flapis not present, the air supplycan be adjusted solely by the speed of the fan. Pulse width modulation can come into consideration for adjusting the speed of the fanfor example. In accordance with another form of embodiment the motor of the fanis connected to a converter. The speed of the fanis thus adjusted via the frequency of the converter.

In some embodiments, the fanruns at a fixed, non-changeable speed. The air supplyis then determined by the position of the flap. Moreover further actuators are possible that change the air supply. These can for example involve a contact tip holder adjustment of the burner and/or an adjustable flap in the exhaust gas channel.

The supply(for example particle flow and/or mass flow) of the fluid fuel through the fuel supply channelcan be set by a fuel flap. In accordance with one form of embodiment the fuel flapis a (motor-adjustable) valve.

Combustible gases such as natural gas and/or propane gas and/or hydrogen can come into consideration as fuel for example. A liquid fuel such as heating oil can also come into consideration as a fuel. In this case the flapis replaced by a motor-adjustable oil pressure regulator in the return of the oil nozzle. The safety shutdown function and/or close function is implemented by the redundant safety valves,. In accordance with a specific form of embodiment the safety valves,and/or the fuel flapare realized as an integrated unit or units.

Fuel is mixed with air in and/or before the burner. The mixture is burned in the combustion chamber of the heat consumer. The heat is transported further on in the heat consumer. For example heated water is taken away via a pump to heating elements and/or in industrial firing systems a commodity is heated (directly). The exhaust gas streamis vented via an exhaust gas path, for example a chimney, (into the environment). The exhaust gas streamcan further be taken away via an exhaust gas path, for example a hearth, (into the environment).

A closed-loop control and/or open-loop control and/or supervision facilityautomates at least one actuator of the combustion apparatus. In some embodiments, the closed-loop control and/or open-loop control and/or supervision facilityautomates a number of or all actuators of the combustion apparatus. Thus the correct supplyof fuel and/or fuel gas is set via the position of the flapfor the corresponding supplyof air for each point of delivery. This produces the desired air/fuel ratio λ.

In some embodiments, the closed-loop control and/or open-loop control and/or supervision facilitycomprises a microcontroller. In some embodiments, the closed-loop control and/or open-loop control and/or supervision facilityis configured as a microcontroller. In some embodiments, the closed-loop control and/or open-loop control and/or supervision facilitycomprises a microprocessor. In some embodiments, the closed-loop control and/or open-loop control and/or supervision facilityis configured as a microprocessor.

The closed-loop control and/or open-loop control and/or supervision facilityautomates the fanwith the aid of the signal lineand/or the air flapwith the aid of the signal line. Values stored in the closed-loop control and/or open-loop control and/or supervision facilitycan be used for this purpose. The values stored in the closed-loop control and/or open-loop control and/or supervision facilitycan be stored for example in the form of a characteristic curve and/or in the form of a mathematical relationship.