Method, computer program and control for controlling a heating device and heating device for generating heat

Abstract

A method for controlling a heating device (20) for heating a room in a building by means of combustion, comprising the steps of: detecting a sensor signal from a lambda probe (22) of the heating device (20) while the heating device (20) is in a first operating state in which no exhaust gases are generated by the heating device (20); supplying air to the lambda probe (22) by means of a fan, before and / or during the step of detecting the sensor signal of the lambda probe (22); determining a calibration value as a function of the detected sensor signal; determining an air pressure as a function of the calibration value; operating the heating device (20) in a second operating state in which exhaust gases are generated by combustion; supplying an exhaust gas generated during the combustion to the lambda probe (22) and detecting the sensor signal of the lambda probe (22);Determining an oxygen value from the sensor signal of the lambda probe and the calibration value while the heating device is in the second operating state, and controlling the heating device (20) as a function of the determined air pressure and the oxygen value,

Description

Technical background

[0001] The performance of a combustion system can be controlled by, among other things, the oxygen supply and the fuel supply. In most applications, oxygen is added to the combustion process by adding air (ambient air).

[0002] With increasing altitude above sea level, air pressure decreases, leading to a decrease in the density of the air and thus in the oxygen content. However, since the mass flow rate depends on the density of a medium, the performance of a combustion plant is significantly influenced by the installation altitude above sea level.

[0003] DE 20 2012 002 439 U1 describes a heating device comprising a base unit for stationary installation in a heating system and a heat generator. The heating device automatically adjusts the fan speed to take air pressure into account. The altitude adjustment refers to the altitude above sea level.

[0004] WO 2003 / 098123 A2 discloses a water heating system comprising a heater and a microcontroller for adjusting the system components. The settings are changed depending on the atmospheric pressure. The atmospheric pressure is determined using an atmospheric pressure sensor. The sensor is designed to vary the fan speed depending on the atmospheric pressure. The atmospheric pressure depends on the position above sea level. The microcontroller is programmed to control the fan speed depending on the information transmitted by the sensor.

[0005] German patent DE 10 2010 054 607 B3 discloses a method for operating a cooking appliance for commercial kitchens with a steam generator, the steam generated by which is fed into a cooking chamber. The quality of the cooked product depends on the reproducibility of the cooking process. One problem related to reproducibility is that the boiling point of water depends on atmospheric pressure. The atmospheric pressure fluctuates within a day or within several days, and it also depends on the geodetic altitude of the location where the cooking appliance is installed. The document proposes determining the oxygen partial pressure using a lambda probe, determining the actual ambient pressure based on the determined oxygen partial pressure, and calibrating the cooking appliance based on the actual ambient pressure. Description

[0006] Based on this, the object of the invention is to determine the air pressure or the installation altitude in a particularly automated and cost-effective manner and to adapt the control of the heating device accordingly to the air pressure or the installation altitude. This object is achieved by the features of the independent claims. The dependent claims relate to particular embodiments of the invention.

[0007] One aspect of the invention relates to a method for controlling a heating device. A heating device can be a device configured to generate heat by means of combustion. Examples of a heating device are a gas boiler, a gas water heater, a biomass boiler, an oil boiler, etc. Advantageously, the heating device can be configured or intended to heat a room in a building. The method comprises the steps of detecting a sensor signal from a lambda probe, determining an air pressure as a function of the detected sensor signal, and controlling the heating device as a function of the determined air pressure. The lambda probe can be configured to output a sensor signal as a function of an air-gas mixture ratio in a measurement environment of the lambda probe.In some embodiments, the lambda sensor can be configured to output a sensor signal depending on the oxygen concentration in the measurement environment of the lambda sensor. An exemplary structure and an example of the operation of a lambda sensor can be found in patent DE 103 00 248 B4. Advantageously, the lambda sensor can be a broadband lambda sensor configured to detect lambda values, in particular between λ=1.1 and λ=1.6.

[0008] The air pressure can be determined by associating the sensor signal with an air pressure, in particular using a characteristic curve and / or a mathematical function. The mathematical function can preferably be configured to represent a relationship between the sensor signal of the lambda probe and an air pressure. Controlling the lambda probe as a function of the determined air pressure can include adjusting a fan speed and / or adjusting a fuel supply.

[0009] This can have the advantage of allowing the air pressure in the vicinity of the heater to be determined using the existing lambda sensor. This saves space and costs. In particular, the method eliminates the need for a separate altitude sensor, thus saving space and costs.

[0010] In a particularly advantageous embodiment, the sensor signal of the lambda sensor can depend on the oxygen concentration detected by the lambda sensor. The oxygen concentration can be detected, for example, by means of a pumping current, using the oxygen diffused into or out of the measuring chamber to the measuring cell (Nernst cell). Since the oxygen content in the air can be assumed to be approximately constant with respect to the installation altitude, the air pressure can be determined particularly reliably based on the detection of the oxygen concentration.

[0011] A particularly advanced embodiment can include the step of determining an installation altitude of the heating device as a function of the air pressure, with the heating device being controlled as a function of the determined installation altitude. This can have the advantage that the heating device can be operated in a manner specifically adapted to the installation altitude. For example, a fan speed of a fan of the heating device and / or a fuel supply can be adjusted so that the heating output of the heating device is adjusted to a predetermined heating output.

[0012] In a particularly reliable embodiment, the method can include the step of supplying air to the lambda sensor, for example, into a measurement environment of the lambda sensor, in particular by means of a fan, before and / or during the step of detecting the sensor signal of the lambda sensor. This can have the advantage that the sensor signal for determining the air pressure is not distorted due to (residual) exhaust gases. Thus, the reliability and accuracy of the determined air pressure can be improved. This, in turn, leads to a control of the heating device that is better adapted to the ambient parameters, such as air pressure and / or installation altitude.

[0013] In a particularly advantageous embodiment, the step of detecting the sensor signal of the lambda probe can be performed while the heating device is in an operating state in which no exhaust gases are generated by the heating device. This has the advantage that corruption of the sensor signal for determining the air pressure, in particular due to exhaust gases, can be avoided. This operating state, in which no exhaust gases are generated by the heating device, can be, for example, a standby state, a pre-ventilation state, or a post-ventilation state. Advantageously, one or more, in particular all, of the aforementioned operating states can be integrated into a heating device as standard.

[0014] In a particularly automated embodiment, the process steps can be integrated into an existing operating sequence of the heating device.

[0015] In some embodiments, the partial pressure in a measurement environment of the lambda sensor can be determined by the lambda sensor based on a pumping current of the lambda sensor to determine the atmospheric pressure. The sensor signal of the lambda sensor can then be provided for detection, for example, depending on the pumping current. Exhaust gases can distort the signal in this case.

[0016] In a particularly advantageous embodiment, the air pressure can also be determined based on a first characteristic curve, and the oxygen content and / or an air-gas mixture ratio can be determined using the lambda sensor based on a second characteristic curve. In some embodiments, the air pressure can be determined based on the sensor signal using a first mathematical function. In some embodiments, the oxygen content and / or the air-gas mixture ratio can be determined using the lambda sensor based on a second mathematical function. Advantageously, the first characteristic curve or the first mathematical function can differ from the second characteristic curve or the second mathematical function.In some embodiments, the first characteristic curve, the second characteristic curve, the first mathematical function and / or the second mathematical function may depend on an embodiment of the lambda sensor.

[0017] In a particularly reliable embodiment, the sensor signal can be detected at one or more points in time, in particular at two points in time, and the air pressure can be determined as a function of the detected sensor signals at the one or more points in time. If the sensor signal is detected once before a first combustion operation of the heating device, it can be ensured that the sensor signal is not corrupted due to exhaust gas residues in the heating device. If the sensor signal is detected at multiple points in time, corruption of the sensor signal of the lambda probe can be detected or reduced by using the multiple sensor signals. In particular, this makes it possible to reduce only temporary influences that corrupt the sensor signal of the lambda probe when determining the air pressure.

[0018] In some embodiments, the determination of the installation altitude can be improved by recording the sensor signal at two or more points in time. In particular, fluctuations in air pressure, for example, due to weather conditions, time of day, season, etc., can be taken into account.

[0019] In specially adapted embodiments, the air pressure can be determined based on the time at which the sensor signal is detected. In some embodiments, the installation altitude can be determined based on the time at which the sensor signal is detected. Taking into account the time at which the sensor signal of the lambda probe is detected can have the advantage that fluctuations in air pressure, for example, due to a season, a time of day, weather conditions, etc., are taken into account when controlling the heating device.

[0020] One aspect of the invention relates to a computer program comprising program instructions for executing a previously described method.

[0021] Another aspect of the invention relates to a heating device for generating heat. The heating device comprises a control unit for controlling the heating device and a lambda probe for determining an air-gas mixture ratio. The control unit is configured to detect a sensor signal from the lambda probe, determine an air pressure as a function of the detected sensor signal, and control the heating device as a function of the determined air pressure. Advantageously, the lambda probe can be a broadband lambda probe configured to detect air-gas mixture ratios, in particular from λ=1.1 to λ=1.6.

[0022] In a particularly advantageous embodiment, the lambda sensor can include an oxygen pump cell, and the sensor signal can optionally be dependent on a pump current of the lambda sensor. In some embodiments, the sensor signal of the lambda sensor can be the pump current of the lambda sensor. In some embodiments, the lambda sensor can comprise an oxygen pump cell and a Nernst cell. Using a mathematical formula, an air-gas mixture ratio and / or an oxygen content can be calculated / determined depending on the sensor signal and / or the pump current. This has the advantage of utilizing a particularly advantageous interaction between air pressure and the sensor signal.

[0023] In a particularly advanced embodiment, the control unit can be configured to control a fan speed of a fan of the heating device and / or a fuel supply to the heating device depending on the determined air pressure. In some embodiments, the control unit can be configured to control one or more servomotors for an air supply to the heating unit depending on the determined air pressure. In some embodiments, the control unit can be configured to determine an installation altitude depending on the determined air pressure. The control unit can then be configured to control the fan speed of the fan of the heating device, the one or more servomotors for an air supply to the heating unit and / or a fuel supply to the heating device depending on the determined installation altitude.

[0024] At lower air pressure, the performance of the heating device, in particular the heating power, decreases. By adjusting the fan speed, in particular by increasing the fan speed, this loss of performance of the heating device, in particular the heating power, can be compensated. In particular, by adjusting the speed of the fan of the heating device, a predetermined air volume or a predetermined air mass flow can be supplied to a combustion process of the heating device, so that a predetermined performance is achieved by the heating device.

[0025] One aspect of the invention relates to a controller for controlling the heating device. The controller is configured to determine an air pressure as a function of a sensor signal from a lambda probe and to control the heating device as a function of the determined air pressure. Advantageously, the lambda probe can be a broadband lambda probe. Character description Fig. 1 schematically shows a method according to an embodiment of the invention. Fig. 2 schematically shows a heating device according to an embodiment of the invention. Fig. 3 schematically shows a control according to an embodiment of the invention.

[0026] Fig. Figure 1 schematically shows a method according to one embodiment of the invention. In the method, steps can be interchanged in their order, combined, divided into multiple steps, and / or added without affecting the essence of the invention. The method can advantageously be used to control a heating device. The heating device can preferably be configured to heat one or more rooms in one or more buildings.

[0027] In a first step S11, a sensor signal from a lambda sensor is detected. Detecting the sensor signal from the lambda sensor may include sampling an analog signal, receiving / retrieving a digital value, and / or reading a sensor value from the lambda sensor stored in a memory unit. Advantageously, the lambda sensor may be a broadband lambda sensor.

[0028] In step S12, an air pressure is determined based on the detected sensor signal. The air pressure can be determined, for example, using a (first) characteristic curve, a (first) mathematical function, and / or a mathematical or physical formula. The characteristic curve (first characteristic curve) can be configured to represent a relationship between the detected sensor signal and an air pressure.

[0029] A further step S13 involves controlling the heating device as a function of the determined air pressure. Controlling the heating device may, for example, include controlling a fan speed of a fan of the heating device, a fuel supply of the heating device, and / or a servomotor, in particular for controlling an air supply of the heating device, as a function of the air pressure.

[0030] In some embodiments, the method may optionally include a step S14 for determining an installation altitude of the heating device as a function of the air pressure. For this purpose, a (third) characteristic curve, a (third) mathematical function, or a mathematical / physical formula can be used, for example. Control of the heating device in step S13, in particular the control of the fan speed, the fuel supply, and the servomotor, can then be carried out as a function of the installation altitude.

[0031] In some embodiments, the method can optionally include a step S15 of supplying air to the lambda probe, in particular by means of a fan, before and / or during step S11 of detecting the sensor signal of the lambda probe. Advantageously, no exhaust gases are generated by the heating device during step S11. In particularly advantageous embodiments, (ambient) air of the measurement environment of the lambda probe is supplied before and / or during step S11. This can ensure that the sensor signal of the lambda probe, which is used to determine the air pressure, is not distorted by exhaust gases or is distorted as little as possible.

[0032] Advantageously, the lambda sensor signal acquired in step S11 can also be used to calibrate the lambda sensor. By means of the calibration, during an operating state in which combustion is controlled by the heating device, the lambda sensor signal can be used to infer an air-gas mixture ratio in a measurement environment of the lambda sensor. The relationship between the sensor signal and the air-gas mixture ratio can then be established depending on a (second) characteristic curve, a (second) mathematical function, a mathematical / physical formula, and the calibration.

[0033] Fig. Figure 2 schematically shows a heating device according to one embodiment of the invention. The heating device 20 comprises a control unit 21 configured to control the heating device 20, for example, a fuel supply unit 24 and / or a fan 23. The fuel supply unit 24 and / or the fan 23 can each optionally be part of the heating device 20.

[0034] The heating device comprises a lambda probe 22. The lambda probe can advantageously comprise an oxygen pump cell 221. The lambda probe can then output a sensor signal depending on a pump current that stimulates oxygen diffusion into the oxygen pump cell 221 or out of the oxygen pump cell.

[0035] The control unit 21 is configured to detect a sensor signal of the lambda probe, to determine an air pressure as a function of the detected sensor signal, and to control the heating device as a function of the determined air pressure.

[0036] Fig. Figure 3 schematically shows a controller according to one embodiment of the invention. The controller 30 is configured to determine an air pressure based on a sensor signal from a lambda probe 22 and to control a heating device 31 based on the determined air pressure.

[0037] In some embodiments, an oxygen value O2 can be determined using the lambda sensor as follows: O2 = A * Ip 2 * Cal 2 + B * Ip * Cal. A and B are fixed sensor-specific factors of the lambda sensor. Ip is the pumping current of the pump cell. Cal is a calibration value determined in an air environment, e.g., during pre-ventilation. This is preferably 1.0, especially under nominal conditions.

[0038] In general, if the air pressure drops, the partial pressure of oxygen also decreases. Less oxygen diffuses into the measuring chamber of a lambda sensor. This results in a lower pumping current (fewer oxygen molecules need to be pumped out of the measuring cell). This lower pumping current results in a higher calibration value, Cal, according to the formula.

[0039] In a preferred embodiment, the lambda sensor is calibrated in air during pre-ventilation, standby, post-ventilation, etc. of the heating device. The calibration value can then be incorporated into the characteristic curve for the correct determination of the oxygen content during an operating state in which the heating device generates exhaust gases by burning a fuel (combustion mode). In some embodiments, the calibration value (Cal), which was determined as a function of a detected sensor signal from the lambda sensor, can be used to determine the air pressure.

[0040] A change in air pressure can be considered a disturbance for the air ratio measurement or the oxygen concentration measurement. This deviation, which is compensated for by calibration when determining the oxygen content during combustion operation, can be used to determine the air pressure or an installation altitude. The relationship between air pressure and the calibration value can be represented, for example, using a characteristic curve, a mathematical function and / or a mathematical / physical formula. As a result, the control of the heating device, in particular the speed of a fan of the heating device, the fuel supply, and a stepper motor, can be controlled depending on the air pressure or the installation altitude.

[0041] If the air pressure drops, the oxygen partial pressure also drops, and less oxygen diffuses into the lambda sensor's measuring chamber. This can result in a lower pumping current (fewer oxygen molecules need to be pumped out of the measuring cell). The lambda sensor's sensor signal can change accordingly.

[0042] Using the calibration value Cal, the correct oxygen value can now be determined from the lambda sensor signal while the heater is in an operating state in which exhaust gases are generated by combustion. For this purpose, an air-gas mixture, in particular the exhaust gas or an air-fuel mixture, is advantageously fed to the lambda sensor, in particular into a measurement environment of the lambda sensor.

[0043] The air pressure can be determined using the calibration value Cal or the sensor signal of the lambda probe and a characteristic curve, a mathematical function, and / or a mathematical / physical formula. Advantageously, the heating device is in an operating state during the acquisition of the sensor signal used to determine the air pressure, in which no exhaust gases are generated by the heating device.

[0044] In some embodiments, a speed correction for the fan can be determined directly as a function of the sensor signal from the lambda probe using an alternative characteristic curve, an alternative mathematical function, and / or an alternative mathematical / physical formula. This speed correction can then be used to adjust the air volume supplied to the combustion of the heating device or the air mass flow supplied to the combustion of the heating device. This allows the heating output of the device to be adjusted. This has the positive effect that a reduced air volume or a reduced air mass flow due to lower air pressure can be compensated for with regard to the performance, in particular the heating output, of the heating device.

Claims

[1] Method for controlling a heating device (20) for heating a room in a building by means of combustion, comprising the steps: detecting a sensor signal of a lambda probe (22) of the heating device (20) while the heating device (20) is in a first operating state in which no exhaust gases are generated by the heating device (20), Supplying air to the lambda probe (22) by means of a fan, before and / or during the step of detecting the sensor signal of the lambda probe (22), Determining a calibration value depending on the recorded sensor signal, Determining an air pressure depending on the calibration value, Operating the heating device (20) in a second operating state in which exhaust gases are generated by combustion, Supplying an exhaust gas generated during combustion to the lambda probe (22) and detecting the sensor signal of the lambda probe (22), Determining an oxygen value from the sensor signal of the lambda probe and the calibration value while the heating device is in the second operating state, and Controlling the heating device (20) depending on the determined air pressure and the oxygen value [2] Method according to claim 1, wherein the sensor signal of the lambda probe (22) depends on an oxygen concentration detected by the lambda probe (22). [3] Method according to claim 1 or 2 comprising the step: Determining an installation height of the heating device (20) as a function of the air pressure, wherein the heating device (20) is controlled depending on the determined installation height. [4] A method according to any one of claims 1 to 3, wherein the oxygen value is determined using the following equation O2=A*Ip2*Cal2+B*Ip*Cal, where A and B are fixed sensor-specific factors of the lambda probe (22), Ip is a pumping current of a pumping cell (221) of the lambda probe (22) and Kal is the calibration value. [5] Method according to one of claims 1 to 4, wherein the determination of the air pressure is carried out as a function of a first characteristic curve and the determination of an oxygen content by means of the lambda probe (22) is carried out as a function of a second characteristic curve. [6] Method according to one of claims 1 to 5, wherein the detection of the sensor signal takes place at one or more points in time and the determination of the air pressure takes place as a function of the detected sensor signals at the one or more points in time. [7] Method according to one of claims 1 to 6, wherein the determination of the air pressure takes place as a function of a time at which the sensor signal is detected. [8] Computer program comprising program instructions for carrying out a method according to one of claims 1 to 7. [9] Heating device (20) for generating heat for heating a room in a building by means of combustion, comprising: a control unit (21) for controlling the heating device (20), and a lambda probe (22) arranged in an exhaust gas path of the heating device (20) for determining an air-gas mixing ratio, a blower (23) which is designed to supply air and / or exhaust gases from the combustion to the lambda probe (22), wherein the control unit (21) is configured to carry out a method according to one of claims 1 to 7. [10] Heating device (20) according to claim 9, wherein the lambda probe (22) includes an oxygen pump cell (221), and the sensor signal may be dependent on a pump current. [11] Heating device (20) according to claim 9 or 10, wherein the control unit (21) is configured to control a fan speed of the fan (23) and / or a fuel supply (24) of the heating device (20) as a function of the determined air pressure. [12] Controller (30) for controlling a heating device (20), wherein the controller (30) is configured to carry out a method according to one of claims 1 to 7.

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