Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N5/00—Systems for controlling combustion
  • F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
  • F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/002—Regulating fuel supply using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/02—Regulating fuel supply conjointly with air supply
  • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N5/00—Systems for controlling combustion
  • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
  • F23N5/184—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
  • F23K2400/00—Pretreatment and supply of gaseous fuel
  • F23K2400/20—Supply line arrangements
  • F23K2400/201—Control devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
  • F23K2900/00—Special features of, or arrangements for fuel supplies
  • F23K2900/05001—Control or safety devices in gaseous or liquid fuel supply lines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
  • F23K2900/00—Special features of, or arrangements for fuel supplies
  • F23K2900/05002—Valves for gaseous fuel supply lines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/04—Measuring pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2231/00—Fail safe
  • F23N2231/10—Fail safe for component failures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2233/00—Ventilators
  • F23N2233/06—Ventilators at the air intake
  • F23N2233/08—Ventilators at the air intake with variable speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2235/00—Valves, nozzles or pumps
  • F23N2235/12—Fuel valves
  • F23N2235/16—Fuel valves variable flow or proportional valves

Definitions

• the invention relates to a gas control unit, a gas control valve with such a gas control unit and a system with such a gas control valve for the fail-safe control of a gas on or in a gas heating device, in particular a gas boiler, as well as a method for the plausibility check of differential pressures which were detected by such a gas control unit, such a gas control valve and/or such a system.
• Gas control valves for regulating a gas and in particular for pressure control are known in the state of the art and for example from the document DE 10 2018 102 866 A1
• the gas is mixed with air to form the gas-air mixture is mixed, and furthermore a gas control valve is used upstream of a main flow throttle to adjust or regulate the gas flow flowing into the mixing device, in particular volume or mass flow.
• the measured values of a single differential pressure sensor are used for pressure control, which determines the pressure difference or the differential pressure between a process pressure of the gas, usually the pressure of the gas outflow or downstream of the gas control valve or the pressure of the gas at a first measuring point between the gas control valve and the main flow throttle, and a reference pressure, usually the pressure of the air in the vicinity of the pressure control valve, which flows into the mixing device.
• the gas control valve or an actuator that determines the flow through the gas control valve is adjusted to a setpoint of 0 Pa by means of an actuator, for example a motor, usually with a so-called zero pressure control.
• the invention is therefore based on the object of overcoming the aforementioned disadvantages and of providing a gas control unit or a gas control valve comprising such a gas control unit, with which a fail-safe operation of a gas heater in particular is possible.
• a gas control unit for the fail-safe control of a gas, in particular in a gas heater or a gas burner, furthermore in particular in a gas boiler.
• the gas control unit has a communication interface, a first sensor module, and a second sensor module.
• the first sensor module is designed to record measured values from which a signed first differential pressure between a process pressure of the gas and a reference pressure can be determined or which is such a first differential pressure.
• the second sensor module is designed to record measured values from which a signed second differential pressure between the reference pressure and the process pressure can be determined or which is the second differential pressure.
• the measured values or differential pressures are determined by means of the sensor modules such that the signed first differential pressure and the signed second differential pressure are signed, mutually inverse differential pressures. Furthermore, the invention provides that the communication interface is designed to send the mutually inverse differential pressures and/or the measured values to an external receiver, i.e. to a receiver outside the gas control unit.
• the differential pressure on which the control of the gas is preferably based, is recorded not only twice but inversely to each other, the sign is available as additional information that can be evaluated in addition to the respective differential pressures.
• the gas control unit itself does not have to check the values in a fail-safe manner, since these can be provided to an external receiver via the communication interface, for example the control unit, as explained below.
• the process pressure applied to or determinable with the first sensor assembly is the process pressure or corresponds to the process pressure applied to or determinable with the second sensor assembly.
• each of the sensor modules is a differential pressure sensor, which can therefore detect the respective differential pressure directly
• each of the sensor modules is a mass flow sensor, which can therefore detect the differential pressure via the mass flow
• a sensor module is formed from two or more individual sensors, each of which can determine a pressure so that the differential pressure can be determined from the individual pressures.
• Such sensors can be pressure or absolute pressure sensors, but also, for example, mass flow sensors.
• the different sensors can also be mixed, so that, for example, the first sensor module is a differential pressure sensor and the second sensor module has two sensors, of which a first sensor is a pressure sensor and a second sensor is a mass flow sensor.
• the first sensor assembly can be a first differential pressure or mass flow sensor or can comprise at least two sensors, each configured as a pressure sensor or a mass flow sensor.
• the second sensor assembly can be a second differential pressure or mass flow sensor or can comprise at least two sensors, each configured as a pressure sensor or a mass flow sensor.
• the gas control unit preferably has exactly one first and exactly one second sensor assembly, although alternatively, more than two sensor assemblies may be provided. If more than two sensor assemblies are provided, they are preferably grouped in pairs, and accordingly, several pairs of sensor assemblies are provided.
• the first sensor assembly is a first differential pressure sensor and the second sensor assembly is a second differential pressure sensor.
• the differential pressure sensors each have a first pressure input and a second pressure input and are designed to determine a differential pressure by subtracting a pressure present at the second pressure input from a pressure present at the first pressure input. If the pressure at the second pressure input is higher than the pressure at the first pressure input, a negative value results for the differential pressure determined by this differential pressure sensor. If the pressure at the second pressure input is lower than the pressure at the first pressure input, a positive value results for the differential pressure determined by this differential pressure sensor.
• the process pressure is applied to the first pressure input of the first differential pressure sensor and a reference pressure is applied to the second pressure input of the first differential pressure sensor.
• the reference pressure is applied to the first pressure input of the second differential pressure sensor and the process pressure is applied to the second pressure input of the second differential pressure sensor, so that the differential pressures determined by the two differential pressure sensors are signed and inverse to each other or have an opposite sign if the differential pressures are not equal to 0 Pa.
• the same pressure which can be referred to as process pressure
• the second pressure input of the first differential pressure sensor and at the first pressure input of the second differential pressure sensor the same pressure, which can be referred to as reference pressure
• the differential pressures determined by the two differential pressure sensors are inverse to one another, ie the pressure values representing the respective differential pressure have an opposite sign to one another.
• a separate pressure channel can be provided for connecting or applying the pressures (process pressure, reference pressure) to the pressure inputs, so that from a process pressure measuring point a pressure channel can lead to the first pressure input of the first differential pressure sensor and to the second pressure input of the second differential pressure sensor and/or from a reference pressure measuring point a pressure channel can lead to the second pressure input of the first differential pressure sensor and to the first pressure input of the second differential pressure sensor.
• the pressure channels leading from the respective measuring points to the differential pressure sensors can also be formed integrally with one another, at least in sections, so that a single pressure channel can lead from the process pressure measuring point, at least in sections, to the first pressure input of the first differential pressure sensor and to the second pressure input of the second differential pressure sensor and/or from a reference pressure measuring point, at least in sections, a single pressure channel can lead to the second pressure input of the first differential pressure sensor and to the first pressure input of the second differential pressure sensor.
• one pressure sensor can essentially be equated with one pressure input of a differential pressure sensor.
• the process pressure is preferably a gas pressure of a gas regulated by the gas control unit or the gas pressure of a gas flowing through the gas burner/gas heater and in particular the gas boiler.
• the process pressure measuring point is preferably located on the outflow side of the gas control valve, but upstream of any mixing device or upstream of any main flow throttle, so that the process pressure corresponds to the gas pressure of a fuel gas on the outflow side of the gas control valve. If the process pressure measuring point is upstream of the mixing device, the process pressure can also be referred to as the suction pressure. If a Venturi mixer is used as the mixing device, the process pressure can be referred to as the Venturi suction pressure.
• the reference pressure can also preferably be an ambient or air pressure in an environment of the gas control unit or in an environment of the gas control valve or system mentioned below, so that the reference pressure measuring point is arranged accordingly in or on the respective environment.
• the reference pressure preferably corresponds to the pressure or air pressure at an air inlet of the mixing device. In principle, however, other reference pressures are also possible, so the reference pressure does not necessarily have to be the ambient pressure or the air pressure at the air inlet of the mixing device.
• the sensor modules can determine the respective measured values or the respective differential pressure within a mostly known accuracy or tolerance, so that the differential pressures in reality and in border areas (close to or at 0 Pa) do not necessarily have to have an opposite sign and there may be a deviation in the amounts of the differential pressures determined with the sensor modules.
• the pressure values are merely the differential pressures represented as signed values, so that the first signed pressure value, which represents the first differential pressure p11 that can be determined by means of the first sensor assembly, can be referred to as pressure value p11 and the second signed pressure value, which represents the second differential pressure p12 that can be determined by means of the second sensor assembly, can be referred to as pressure value p12.
• the proposed gas control unit provides that it further comprises control electronics that are signal-connected to the first sensor assembly and the second sensor assembly. Furthermore, such a variant provides that the control electronics are configured to detect the mutually inverse differential pressures, in particular as a respective signed pressure value, or to determine them from the measured values detected by the sensor assemblies.
• a similarly advantageous embodiment of the gas control unit provides for it to have an actuator interface for controlling an actuator, wherein the actuator can be, in particular, a stepper motor.
• the actuator interface is connected to the control electronics for signaling purposes or is formed integrally with the control electronics.
• the actuator interface can be understood as a pure interface for connecting the actuator or, alternatively, as actuator control electronics.
• the communication interface which can also be understood as a pure interface or as communication electronics, can be connected to the control electronics for signaling purposes or be designed integrally with the control electronics.
• the communication interface is designed to send the signed pressure values to an external receiver.
• the communication interface is also designed to receive control signals.
• the communication interface can alternatively be designed for optical signal transmission or for wireless sending and receiving, so that data can be transmitted, for example, via radio.
• a further aspect of the invention relates to a gas control valve for fail-safe control of a gas and in particular pressure control or zero pressure control in a gas heater or a gas burner, in particular a gas boiler, wherein said valve comprises the gas control unit proposed according to the invention.
• the gas control valve further comprises an actuator for adjusting a flow rate of a gas flowing from an inflow side to an outflow side of the gas control valve, wherein the gas is preferably a fuel gas to be burned in the gas burner or the gas heater.
• the process pressure here is the pressure of the gas on the outflow side of the gas control valve or the pressure in the gas control valve on the outflow side of the actuator.
• the flow of gas through the gas control valve can also be referred to as gas flow, whereby the gas control valve is intended to regulate in particular the volume flow and/or the mass flow of the gas.
• gas control valve or actuator and gas control unit are not just a system of several components connected to one another, for example by cables, but they preferably form an integral unit.
• the reference pressure is, in particular, an ambient pressure at the gas control unit and/or the gas control valve, whereby the reference pressure can also be measured at other points or correspond to the ambient pressure at other points.
• the reference pressure can also correspond to the ambient pressure or the air pressure at an air inlet of the mixing device of the gas burner or gas heater.
• the gas control valve can also have an actuator that is signal-connected to the actuator interface of the gas control unit or an actuator controlled via the actuator interface, which actuator is preferably a stepper motor.
• the actuator or stepper motor is designed to adjust the control element to adjust the flow rate and thereby regulate the volume and/or mass flow of the gas through the gas control valve.
• control electronics of such a gas control valve are also designed to adjust the actuator for adjusting the flow rate by controlling the actuator or stepper motor until at least one of the differential pressures or measured values corresponds to a predetermined value and, for example, at least one of the differential pressures is 0 Pa, so that zero-pressure control can be implemented directly by the control electronics or the gas control valve.
• the predetermined value can be stored in the control electronics or specified or transmitted to the control electronics via the communication interface.
• the predetermined value can be transmitted to the control electronics via the communication interface from a control unit explained below.
• a further aspect of the invention relates to a system for the fail-safe control of a gas in a gas heater or a gas burner, in particular a gas boiler.
• the control is further preferably a pressure or zero-pressure control.
• the system comprises a control unit for controlling combustion and a gas control valve proposed according to the invention or at least one gas control unit proposed according to the invention.
• the control unit as an external receiver, is connected to the communication interface of the gas control unit and is designed to receive and process the signed and mutually inverse differential pressures and, additionally or alternatively, to send control signals to the gas control unit, its control electronics, or its communication interface.
• the control unit can assume fail-safe process monitoring in the gas heater or gas burner and, for this purpose, controls individual components of the gas heater/gas burner.
• the gas control unit can be switched and/or controlled to various operating modes by the control unit, particularly via the aforementioned control signals.
• such a control unit is a Class C safety system certified according to IEC EN 60730 or EN 298, so that safe operation of the gas heater/gas burner is possible through the software measures required by Class C and a fail-safe or fault-detecting hardware circuit.
• Gas control valves and gas control units are preferably neither certified according to the aforementioned standards nor fail-safe, which accordingly reduces costs.
• the entire system or system comprising the gas control unit/valve and control unit can be operated in a fail-safe manner by the measures provided according to the invention.
• the control unit can derive from the sign whether the differential pressures are assigned to the correct sensor modules, particularly in the case of a differential pressure not equal to 0 Pa.
• control unit is designed to check the plausibility of the mutually inverse differential pressures by comparing the differential pressures with setpoint values or threshold values stored in the control unit.
• the target or threshold values can also simply correspond to a respective sign, so that it is easy to query whether the signed differential pressures - regardless of their actual value - have an expected or predetermined sign.
• the differential pressure can be adjusted to a value not equal to 0 Pa, resulting in two mutually inverse pressure values or differential pressures, one of which is positive and the other negative and which - neglecting any measurement tolerances and taking a predetermined tolerance into account - are equal in amount. Since the control unit stores in the form of threshold or target values whether the first pressure value should be positive or negative and whether the second pressure value should be positive or negative, it can be determined, i.e.
• control unit can be configured to check the plausibility of the mutually inverse differential pressures by comparing the absolute values of the differential pressures. This allows conclusions to be drawn – taking a tolerance into account – as to whether the sensor modules are delivering correct measured values or differential pressures. If, for example, one of the differential pressures deviates (in absolute value) from the other differential pressure by more than a predetermined tolerance, one of the sensor modules is defective or the transmission is faulty, so the system can then indicate an error, be shut down, or switch to a safe mode.
• control unit is designed to verify the plausibility of the application of the process pressure and the reference pressure to the sensor assemblies. For example, if a differential pressure sensor is assumed as the sensor assembly, the application of the process pressure and the reference pressure to the first The plausibility of the pressure inputs and the second pressure inputs must be checked. If the pressure values are identical, for example, in terms of their signs and – within a tolerance – also in terms of their magnitudes, the same pressure is present at both first inputs of the differential pressure sensors, i.e., process pressure or reference pressure, and the same pressure is also present at the two second inputs of the differential pressure sensors, i.e., reference pressure or process pressure. This means that the system can indicate an error, be shut down, or switched to a safe mode.
• one aspect of the invention relates to a method for checking the plausibility of differential pressures which can be or have been detected with a system for fail-safe pressure control proposed according to the invention and/or a pressure control valve proposed according to the invention and/or a pressure control unit proposed according to the invention.
• the actuator of the gas control valve or a safety valve provided upstream of the gas control valve is controlled, in particular by the control unit, to change the process pressure, so that the signed pressure values change inversely to each other due to the change in the process pressure.
• the process pressure corresponds in particular to a suction pressure, which is generated by a fan arranged downstream of the gas control valve and/or by a mixing device designed in particular as a Venturi mixer. Since the safety valve is particularly active during ventilation of the burner before or after burner operation, for example during a pre-purge phase and/or is or is closed during a post-purge phase of the gas heater/gas burner, the plausibility check can be carried out during ventilation and in particular in the pre-purge or post-purge phase.
• the change in the process pressure exceeds at least a predetermined measurement tolerance of the sensor assemblies, so that measurement tolerances can be essentially neglected for the plausibility check.
• the signed differential pressures determined by the sensor modules after the change in the process pressure are then compared with a respective setpoint or threshold value.
• the system can indicate an error, be shut down or switched to a safe mode.
• a further development of the method provides that an error is detected and output if the signed differential pressures do not correspond to the respective target values or do not reach the respective threshold values.
• FIG 1 a section or part of a gas heating device 1, in particular a gas boiler, is shown schematically and by way of example, wherein the gas control valve 2 shown in Figure 2 and the gas control unit 10 contained therein each represent the gas control valve 2 and the gas control unit 10 according to Figure 1 However, they can also be considered independent of the gas heater 1 or installed in other systems or devices.
• the components and functions of the Figures 1 and 2 described together here, in particular the Figure 2 Also disclosed independently of the exemplary embodiment according to Figure 1 be considered.
• Figure 1 schematically shows a part or section of a gas heater 1 and, more precisely, the schematic structure of a gas-air system of a gas heater 1, wherein a Venturi mixer is shown as the mixing device 7, into which air is sucked from the environment by a fan 8 through an air inlet L at an air pressure p0.
• a Venturi mixer is shown as the mixing device 7, into which air is sucked from the environment by a fan 8 through an air inlet L at an air pressure p0.
• the mixing device 7 the inflowing air and a fuel (gas) flowing in through the fuel supply G are mixed to form a gas-air mixture.
• the gas flowing in from the fuel supply G flows to the mixing device 7 through a safety valve 5 with an actuator 40 adjustable by an actuator 50, a gas control valve 2 with a, for example, as Proportional valve or actuator 30 and a main flow throttle 6.
• the safety valve 5 or its actuator 40 preferably has a pass-through position and a blocking position, between which the actuator 50 can switch. The flow of fuel or gas is permitted in the pass-through position and blocked in the blocking position.
• the safety valve 5 can additionally or alternatively also be manually operable.
• the gas control valve 2 is designed to control the volume or mass flow of the gas, so that the gas or the flow of the gas through the gas control valve 2 to the mixing device 7 can be adjusted or controlled.
• the mixing ratio of the gas-air mixture in the mixing device 7 can thus be regulated or adjusted.
• the gas-air mixture is further conveyed by the blower 8 into a burner 9 or its combustion chamber, in which the combustion of the gas-air mixture takes place.
• the latter has an actuator 30 - as shown, for example, designed as a proportional valve - whose position can be adjusted by an actuator 20 designed in particular as a stepper motor, as well as a gas control unit 10.
• the gas control unit 10 is not itself fail-safe, but comprises, in addition to a control electronics 13, an actuator interface 14 connected to the control electronics 13 for signaling purposes and a signaling two sensor assemblies 11, 12 which are each designed as a differential pressure sensor 11, 12 are connected to the communication interface 15 of the control electronics 13.
• the respective differential pressure p11, p12 is detected by the respective differential pressure sensor 11, 12 not merely as an absolute value (i.e., without a sign), but rather as signed pressure values or signed differential pressures.
• the differential pressures are obtained, for example, by subtracting a pressure applied to the respective second pressure input 11B, 12B from a pressure applied to the respective first pressure input 11A, 12A, so that—depending on the respective pressures present—signed pressure values can result for the differential pressures.
• the same pressure which can be referred to as process pressure p1
• process pressure p1 the same pressure
• reference pressure p0 the same pressure
• the differential pressures p11, p12 determined by the two differential pressure sensors 11, 12 are inverse to one another.
• a separate pressure channel leads to the first pressure inlet 11A of the first differential pressure sensor 11 and to the second pressure inlet 12B of the second differential pressure sensor 12 to the measuring point of the process pressure, whereas the pressure channels from the second pressure inlet 11B of the first Differential pressure sensor 11 and from the first pressure input 12A of the second differential pressure sensor 12 to the measuring point of the reference pressure are formed integrally with each other in sections.
• the process pressure p1 is a gas pressure in the gas control valve 2 on the downstream or outflow side of the actuator 30 and the reference pressure p0 is an air pressure at the gas control valve 2 or at the air inlet L, which, however, can deviate from the ambient pressure p ⁇ .
• the gas control valve 2 itself is not designed to be fail-safe, the gas heater 1 must be capable of fail-safe operation.
• the differential pressures p0, p1 are transmitted from the gas control valve 2 via the communication interface 15 to a control unit 3, which can use these values to check whether a measurement error has occurred.
• control units 3 cannot verify whether the differential pressures assigned to the first differential pressure sensor 11 and the second differential pressure sensor 12 were actually measured by the respective differential pressure sensor 11, 12.
• the signed pressure values are transmitted from the gas control valve 2 or via the communication interface 15 of the gas control unit 10 to the control unit 3.
• the process pressure p1 essentially corresponds to the reference pressure p0, so that the differential pressures p11, p12 fluctuate around 0 (e.g., 0 Pa or 0 bar). Due to measurement inaccuracies, the respective sign usually cannot reliably indicate an error.
• control unit 3 is designed to check the differential pressures p11, p12 for plausibility in certain operating modes or within the framework of certain procedures, ie to check for errors, whereby a pressure diagram is generated in each case according to the Figures 3 and 4 results.
• the plausibility check cannot usually be carried out reliably during normal combustion or burner operation, according to a first process variant - the pressure curve in Figure 3 shown - it is provided that the plausibility check is carried out during or parallel to ventilation and in particular in a pre-purge phase, in which the burner 9 or its combustion chamber is purged or ventilated with air.
• the safety valve 5 and/or the gas control valve 2 is controlled to completely block a gas flow or a gas flow to the mixing device 7 during ventilation and here in the pre-purge phase, wherein the fan 8 continues to suck in air, so that a suction pressure of the fan 8 is established at the process pressure measuring point.
• the described method can also be carried out in a post-purge phase.
• the resulting pressure curve is in Figure 3 shown, wherein at time T1 the fan 8 is switched on with the safety valve 5 and/or gas control valve 2 closed and at time T2 the closed valves (safety valve 5 and/or gas control valve 2) are opened to allow flow.
• a signed maximum pressure value of - 4 is established for the first differential pressure p11 and a signed maximum pressure value of + 4 is established for the second differential pressure, whereby these are represented and assumed to be unitless in the present case.
• differential pressure p12 If the differential pressure p12 is positive and the differential pressure p11 is negative, the differential pressure p12 is correctly assigned to the second differential pressure sensor 12 and the differential pressure p11 is correctly assigned to the first differential pressure sensor 11, so that the differential pressures or pressure values have been verified. If this is not the case, an error has occurred, so an error message is issued and/or the gas heater 1 can be shut down and/or switched to a safe mode.
• a plausibility check by this variant is only possible during ventilation and, for example, in pre-purge operation (or post-purge operation), it can alternatively or additionally be provided that during combustion operation or burner operation the control unit 3 briefly switches to a plausibility check mode in which no zero pressure control takes place for a short time, but - as in Figure 4 shown - a target pressure difference X of, for example, 2 is set, whereby other predetermined target pressure values X are also possible, which, however, should exceed a measuring tolerance of the differential pressure sensors 11, 12.
• a target differential pressure of 2 can be specified to the control electronics 13 via the communication interface 15 by the control unit 3, so that the control electronics 13 regulates the actuator 20 via the actuator electronics or actuator interface 14 such that the new target differential pressure X is established at least briefly at at least one of the differential pressure sensors 11, 12 or both differential pressure sensors 11, 12. Subsequently, and in particular if no error is detected, it is possible to immediately switch back to normal combustion operation.
• differential pressures p11 and p12 do not have the pre-known and stored sign or value for the respective case (p1 ⁇ p0 or p1>p0), the previously known and stored target or threshold value, an error has occurred, so that an error message can be issued accordingly and/or the gas heater 1 can be switched off and/or switched to a safe mode.
• the invention is not limited to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the presented solution even in fundamentally different embodiments.

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• Engineering & Computer Science (AREA)
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• Combustion & Propulsion (AREA)
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• General Engineering & Computer Science (AREA)
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• Fluid Mechanics (AREA)
• Regulation And Control Of Combustion (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Feeding And Controlling Fuel (AREA)

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• 2024
  • 2024-02-27 DE DE102024105404.2A patent/DE102024105404A1/de active Pending
• 2025
  • 2025-02-25 EP EP25160028.4A patent/EP4610568A1/fr active Pending
  • 2025-02-26 US US19/063,609 patent/US20250271879A1/en active Pending

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