Gas Regulating Unit, Gas Regulating Valve And System With Such A Gas Regulating Valve For Fail-Safe Pressure Regulation In A Gas Heater

Abstract

A gas regulating unit (10) for fail-safe regulation of a gas, specifically in a gas heater (1) or a gas burner, has a communication interface (15), a first sensor assembly (11), and a second sensor assembly (12). The first sensor assembly (11) is configured to acquire measured values from which a signed first differential pressure (p11) between a process pressure (p1) of the gas and a reference pressure (p0) is determinable. The second sensor assembly (12) is configured to acquire measured values from which a signed second differential pressure (p12) between the reference pressure (p0) and the process pressure (p1) is determinable. Thus, the signed first differential pressure (p11) and the signed second differential pressure (p12) are signed mutually inverse differential pressures (p11, p12). The communication interface (15) is configured to send the mutually inverse differential pressures (p11, p12) and / or the measured values to an external receiver.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit and priority of German Application No. 10 2024 105 404.2, filed Feb. 27, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The disclosure relates to a gas regulating unit, a gas regulating valve with such a gas regulating unit, and a system with such a gas regulating valve for fail-safe regulation of a gas at or in a gas heater, specifically a gas boiler, as well as to a method for plausibility checking differential pressures acquired by such a gas regulating unit, such a gas regulating valve, and / or such a system.BACKGROUND

[0003] Gas regulating valves for regulation of a gas and specifically for pressure regulation are known in the prior art and, for example, from the document DE 10 2018 102 866 A1. In gas heaters or gas burners in which a gas-air mixture is burned, upstream of a mixing apparatus in which gas is mixed with air to form the gas-air mixture, and further upstream of a main flow restrictor, a gas regulating valve is used with respect to the gas for adjusting or regulating the gas flow, specifically the volumetric or mass flow, flowing into the mixing apparatus.

[0004] Pressure regulation is often provided to use the measured values of an individual differential pressure sensor which determines the pressure difference or the differential pressure between a process pressure of the gas, usually the pressure of the gas on the outflow or discharge side of the gas regulating valve or the pressure of the gas at a first measurement site between the gas regulating valve and the main flow restrictor, and a reference pressure, usually the pressure of the air in the environment of the pressure regulating valve flowing into the mixing apparatus.

[0005] Assuming the acquired differential pressure, the gas regulating valve or a final control element determining the passage through the gas regulating valve is set to a target value of 0 Pa using an actuator, for example a motor, usually using what is known as zero-pressure regulation.

[0006] In principle, it is a problem in this regard that such gas regulating valves or gas regulating units for triggering such gas regulating valves are often not configured to be fail-safe. If they are to be fail-safe, high costs are incurred due to specially provided software, additional hardware required, components present in multiples and necessary certifications, which is correspondingly disadvantageous.

[0007] It is therefore an object of the disclosure to overcome the above-mentioned disadvantages and to provide a gas regulating unit, or a gas regulating valve comprising such a gas regulating unit, which enables fail-safe operation, specifically of a gas heater.SUMMARY

[0008] This object is achieved by the combination of features according to claim 1.

[0009] Hence, according to the disclosure, a gas regulating unit is proposed for fail-safe regulation of a gas, specifically in a gas heater or a gas burner, more specifically in a gas boiler. For this purpose, the gas regulating unit has a communication interface, a first sensor assembly, and a second sensor assembly. In this context, the first sensor assembly is configured to acquire measured values from which a signed first differential pressure between a process pressure of the gas and a reference pressure is determinable, or which is such a first differential pressure. Furthermore, the second sensor assembly is configured to acquire measured values from which a signed second differential pressure between the reference pressure and the process pressure is determinable, or which is the second differential pressure. In this context, the measured values or the differential pressures are determined using the sensor assembly so that the signed first differential pressure and the signed second differential pressure are signed mutually inverse differential pressures. Further, according to the disclosure, the communication interface is provided to be configured to send the mutually inverse differential pressures and / or the measured values to an external receiver, i.e., to a receiver outside the gas regulating unit.

[0010] Due to the differential pressure, on which the regulation of the gas is preferably based, being detected not only twice but inversely to one another, the sign is present as additional evaluable information alongside the respective differential pressures, and moreover, the gas regulation unit itself does not have to check the values in a fail-safe manner, since they may be provided to an external receiver, for example to the control unit, as will be explained below, via the communication interface.

[0011] For clarity, it should be noted that the process pressure which is applied to the first sensor assembly or is determinable using the same is the process pressure or corresponds to the process pressure which is applied to the second sensor assembly or is determinable using the same. This likewise applies to the reference pressure. Neglecting any measuring errors or tolerances, the first differential pressure and the second differential pressure are hence equal in absolute value and correspondingly inverse.

[0012] Although it may be provided that each of the sensor assemblies is a differential pressure sensor, which may consequently acquire the respective differential pressure directly, it may instead also be provided that each of the sensor assemblies is a mass flow sensor, which may consequently acquire the differential pressure via the mass flow, or that each sensor assembly is formed of two or more individual sensors, with a pressure determinable by each of them, so that the differential pressure is ascertainable from the individual pressures. Such sensors may be pressure or absolute pressure sensors, but may also be mass flow sensors, for example. In principle, the various sensors may also be mixed, so that, for example, the first sensor assembly is a differential pressure sensor, and the second sensor assembly has two sensors, of which a first sensor is a pressure sensor, and a second sensor is a mass flow sensor.

[0013] Accordingly, the first sensor assembly may be a first differential pressure or mass flow sensor or may have at least two sensors, each configured as a pressure sensor or as a mass flow sensor. Further, the second sensor assembly may be a second differential pressure or mass flow sensor or may have at least two sensors, each configured as a pressure sensor or as a mass flow sensor.

[0014] In general, the gas regulating unit preferably has exactly one first and exactly one second sensor assembly, but alternatively, more than two sensor assemblies may also be provided. If more than two sensor assemblies are provided, they are preferably grouped in pairs, and correspondingly, a plurality of pairs of sensor assemblies are provided.

[0015] Assuming two differential pressure sensors, an advantageous embodiment variant provides that 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 configured to ascertain a differential pressure by subtracting a pressure applied to the second pressure input from a pressure applied to 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 smaller than the pressure at the first pressure input, a positive value correspondingly results for the differential pressure determined by this differential pressure sensor. In this context, it is provided that the process pressure is applied to the first pressure input of the first differential pressure sensor, and the reference pressure is applied to the second pressure input of the first differential pressure sensor. Conversely, it is further provided that 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 ascertained by the two differential pressure sensors are signed and mutually inverse or have an inverted sign insofar as the differential pressures do not equal 0 Pa.

[0016] Phrased alternatively, it is provided that a same pressure, denotable as the process pressure, is applied or applicable to the first pressure input of the first differential pressure sensor and to the second pressure input of the second differential pressure sensor, as well as a same pressure, denotable as the reference pressure, is applied or applicable to the second pressure input of the first differential pressure sensor and to the first pressure input of the second differential pressure sensor, so that the differential pressures ascertained by the two differential pressure sensors are mutually inverse, i.e., the pressure values representative of the respective differential pressure exhibit a sign which is inverted with respect to one another.

[0017] Insofar as each of the sensor assemblies is a differential pressure sensor, each having two pressure inputs, a separate pressure channel may each be provided for connecting or applying the pressures (process pressure, reference pressure) to the pressure inputs, so that, consequently, one pressure channel may each lead from a process pressure measurement point to the first pressure input of the first differential pressure sensor as well as to the second pressure input of the second differential pressure sensor, and / or one pressure channel may each lead from a reference pressure measurement point to the second pressure input of the first differential pressure sensor as well as to the first pressure input of the second differential pressure sensor.

[0018] Alternatively or in addition thereto, the pressure channels leading from the respective measurement points to the differential pressure sensors may also be formed integrally with one another at least in sections, so that, consequently, a single pressure channel may, at least in sections, lead from the process pressure measurement point to the first pressure input of the first differential pressure sensor as well as to the second pressure input of the second differential pressure sensor, and / or a single pressure channel may, at least in sections, lead from a reference pressure measurement point to the second pressure input of the first differential pressure sensor as well as to the first pressure input of the second differential pressure sensor.

[0019] Assuming a sensor assembly with pressure or absolute pressure sensors, one pressure sensor may be substantially equated to one pressure input of a differential pressure sensor.

[0020] In this context, the process pressure is preferably a gas pressure of a gas regulated by the gas regulating unit or the gas pressure of a gas flowing through the gas burner / gas heater and specifically the gas boiler. With respect to a gas heater or a gas burner, the process pressure measurement point is preferably located on the outflow side of the gas regulating valve but upstream of a mixing device which may be present as appropriate or upstream of a main flow restrictor which may be present as appropriate, so that the process pressure corresponds to the gas pressure of a combustion gas on the outflow side of the gas regulating valve. If the process pressure measurement point is located upstream of the mixing device, the process pressure may also be referred to as a suction pressure. If a venturi mixer is used as the mixing device, the process pressure may be referred to as a venturi suction pressure.

[0021] The reference pressure may also preferably be an ambient or air pressure in an environment of the gas regulating unit or in an environment of the gas regulating valve mentioned further below or of the system, so that the reference pressure measurement point is correspondingly arranged in or at the respective environment. Furthermore, the reference pressure preferably corresponds to the pressure or air pressure at an air inlet of the mixing device. In principle, however, further reference pressures are also possible, so that the reference pressure need not necessarily be the ambient pressure or the air pressure at the air inlet of the mixing device.

[0022] For further clarity, it should be noted that the sensor assemblies may ascertain the respective measured values or the respective differential pressure within an accuracy or tolerance usually previously known, so that in reality and in boundary regions (near or at 0 Pa), the differential pressures do not necessarily have to exhibit an inverted sign and, as appropriate, a deviation of the absolute values of the differential pressures determined using the sensor assemblies may occur.

[0023] Assuming the process pressure p1 and the reference pressure p0, this consequently results in the first differential pressure p11 of the first sensor assembly being p11=p1−p0 and in the second differential pressure p12 of the second sensor assembly being p12=p0−p1.

[0024] If, in simplified terms, an ambient pressure of 1 bar is assumed for the reference pressure p0, and a suction pressure of 0.02 bar is assumed for the process pressure, this results in, for example,p⁢11=p⁢1-p⁢0=0.02 bar-1. bar=-0.98⁢ barp⁢12=p⁢0-p⁢1=1. bar-0.02 bar=+0.98 bar.

[0025] Since, as explained below, it is known and maintained, for example, in the form of target or threshold values, that a negative value must ensue for the first differential pressure p11, and a positive value, but (substantially) identical in absolute value, must ensue for the second differential pressure p12, it may be deduced whether the sensor assemblies or the differential pressure or mass flow sensors are correctly connected, operate correctly, and whether the first differential pressure p11 associated with the first sensor assembly is actually the differential pressure ascertained by the first sensor assembly, or whether the second differential pressure p12 associated with the second sensor assembly is actually the differential pressure ascertained by the second sensor assembly.

[0026] The pressure values are only the differential pressures shown as signed values, so that reference may be made to the first signed pressure value, which is representative of the first differential pressure p11 determinable using the first sensor assembly, as the pressure value p11, and to the second signed pressure value, which is representative of the second differential pressure p12 determinable using the second sensor assembly, as the pressure value p12.

[0027] An advantageous development of the proposed gas regulating unit provides that it further has control electronics signalling connected to the first sensor assembly and the second sensor assembly. Furthermore, such a variant provides for the control electronics to be configured to acquire the mutually inverse differential pressures, specifically as a respective signed pressure value, or to determine them from the measured values acquired by the sensor assemblies.

[0028] Furthermore, a likewise advantageous embodiment of the gas regulating unit provides for it to have an actuator interface for triggering an actuator, wherein the actuator may specifically be a stepper motor. In this regard, the actuator interface is signalling connected to the control electronics or is formed integrally with the control electronics, wherein the actuator interface may be understood as a mere interface for linking the actuator or, alternatively, also as actuator control electronics.

[0029] Furthermore, the communication interface, which may likewise be understood as a mere interface or as communication electronics, may be signalling connected to the control electronics or may be formed integrally with the control electronics. As previously explained, the communication interface is configured to send the signed pressure values to an external receiver. Furthermore, however, it may also be provided that the communication interface is also configured to receive control signals.

[0030] Although the sending and also the optional receiving preferably occur in a wired manner and, for example, via a BUS system, the communication interface may alternatively also be configured for optical signal transfer or for wireless sending and receiving, so that data may consequently be transmitted, for instance, by radio.

[0031] A further aspect of the disclosure relates to a gas regulating valve for fail-safe regulation of a gas and specifically for pressure regulation or zero-pressure regulation in a gas heater or a gas burner, specifically a gas boiler, wherein this comprises the gas regulating unit proposed according to the disclosure. Alongside such a gas regulating unit, the gas regulating valve further has a final control element for adjusting passage of a gas flowing from an inflow side to an outflow side of the gas regulating valve, wherein the gas is preferably a combustion gas to be combusted in the gas burner or in the gas heater. In this regard, the process pressure is the pressure of the gas on the outflow side of the gas regulating valve or the pressure in the gas regulating valve on the outflow side of the final control element.

[0032] The passage of the gas through the gas regulating valve may also be referred to as a gas flow, wherein specifically the volumetric flow and / or the mass flow of the gas is to be regulated by the gas regulating valve.

[0033] Furthermore, it should be noted that the gas regulating valve or final control element and gas regulating unit is not only a system of a plurality of components connected to one another, for example, by cables, but these components preferably form an integral structural unit.

[0034] Furthermore, the reference pressure is specifically an ambient pressure at the gas regulating unit and / or the gas regulating valve, wherein the reference pressure may also be measured at other points or may correspond to the ambient pressure at other points. For example, the reference pressure may also correspond to the ambient pressure or the air pressure at an air inlet of the mixing device of the gas burner or of the gas heater.

[0035] The gas regulating valve may also have an actuator signalling connected to the actuator interface of the gas regulating unit or an actuator triggered via the actuator interface, which is preferably a stepper motor. In this regard, the actuator or stepper motor is configured to adjust the final control element for adjusting the passage and thereby to regulate the volumetric and / or mass flow of the gas through the gas regulating valve.

[0036] Also, the control electronics of such a gas regulating valve are preferably configured to adjust the final control element for adjusting the passage by triggering the actuator or the 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 regulation may consequently be implemented directly by the control electronics or the gas regulating valve. In this context, the predetermined value may be maintained in the control electronics or may be specified or transmitted to the control electronics via the communication interface. For example, the predetermined value may be transmitted to the control electronics via the communication interface from a control unit which will be explained below.

[0037] A further aspect of the disclosure relates to a system for fail-safe regulation of a gas in a gas heater or a gas burner, specifically a gas boiler. The regulation is more preferably pressure or zero-pressure regulation. The system has a control unit for regulating combustion and a gas regulating valve proposed according to the disclosure or at least one gas regulating unit proposed according to the disclosure. According to the proposed system, the control unit is signalling connected to the communication interface of the gas regulating unit as an external receiver and is configured to receive and process the signed and mutually inverse differential pressures as well as, additionally or alternatively, to send control signals to the gas regulating unit, its control electronics, or its communication interface.

[0038] The control unit may take over the fail-safe monitoring of the process in the gas heater or in the gas burner, and for this purpose, controls individual components of the gas heater / the gas burner. Specifically, the gas regulating unit may be switched and / or controlled in various operating modes by the control unit and specifically via the control signals mentioned.

[0039] Preferably, for this purpose, 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 / the gas burner is possible due to the software measures caused by Class C and fail-safe or fault-detecting hardware wiring.

[0040] However, this is precisely not the case for the gas regulating valve or the gas regulating unit. The gas regulating valve or gas regulating unit is preferably neither certified according to the mentioned standards nor fail-safe, which correspondingly reduces costs.

[0041] However, the overall system or system consisting of the gas regulating unit / valve and the control unit may be operated in a fail-safe manner overall by means of the measures provided according to the disclosure.

[0042] In principle, assuming a system with two differential pressure or mass flow sensors, it cannot be excluded that the first differential pressure ascertained by the first differential pressure or mass flow sensor and the second differential pressure ascertained by the second differential pressure or mass flow sensor are interchanged while being transmitted from the differential pressure or mass flow sensors to the control unit, wherein the control unit conventionally does not have any way to plausibility check the differential pressures or pressure values, i.e., check them for certain possible faults.

[0043] Since, according to the disclosure, the differential pressures are determinable in a signed manner, the control unit may infer from the signs, specifically at a differential pressure not equal to 0 Pa, whether the differential pressures are associated with the correct sensor assemblies.

[0044] Correspondingly, a variant of the system provides that the control unit is configured to plausibility check the mutually inverse differential pressures by comparing the differential pressures with target values or threshold values stored in the control unit.

[0045] In this context, the target or threshold values may also simply correspond to a respective sign, so that it may simply be enquired whether the signed differential pressures exhibit an expected or predetermined sign, irrespective of their specific absolute value.

[0046] For example, and as will be explained below, the differential pressure may be changed to a value not equal to 0 Pa by corresponding triggering of the final control element or a different component of the gas heater / the gas burner, whereby two mutually inverse pressure values or differential pressures result, of which, consequently, one pressure value is positive and the other pressure value is negative and which, neglecting any measurement tolerances and taking into account any predetermined tolerance, are equal in absolute value. Since the control unit maintains in the form of the threshold or target values whether the first pressure value is to be positive or negative as well as whether the second pressure value is to be positive or negative, it may be ascertained therefrom, i.e., it may be plausibility checked, whether the first pressure value corresponds to the pressure value of the first sensor assembly and the second pressure value corresponds to the pressure value of the second sensor assembly, or whether these have been transmitted in a faulty and specifically interchanged manner and are associated with the respectively incorrect sensor assembly, so that the system may then indicate a fault, be switched off, or be switched to a safe mode.

[0047] Additionally or alternatively, it may be provided that the control unit is configured to plausibility check the mutually inverse differential pressures by comparing the absolute values of the differential pressures with one another. Thereby, consequently, it may be deduced, taking into account any tolerance, whether the sensor assemblies deliver correct measured values or differential pressures. If, for example, one of the differential pressures (in terms of absolute value) deviates from the other differential pressure beyond a predetermined tolerance, one of the sensor assemblies is defective or the transmission is faulty, so that the system may then indicate a fault, be switched off, or be switched to a safe mode.

[0048] Additionally or alternatively, it may also be provided that the control unit is configured to plausibility check the application of the process pressure and the reference pressure to the sensor assemblies. If, for example, one differential pressure sensor each is assumed as the sensor assembly, the application of the process pressure and the reference pressure at the first pressure inputs and the second pressure inputs may be plausibility checked. If, for example, the pressure values are equal with respect to their signs and, within a tolerance, also with respect to their absolute values, the same pressure, i.e., the process pressure or reference pressure, is applied to both first inputs of the differential pressure sensors, and the same pressure, i.e., the reference pressure or process pressure, is likewise applied to both second inputs of the differential pressure sensors, so that the system may again indicate a fault, be switched off, or be switched to a safe mode.

[0049] Further, one aspect of the disclosure relates to a method for plausibility checking differential pressures acquirable or acquired using a system proposed according to the disclosure for fail-safe pressure regulation and / or a pressure regulating valve proposed according to the disclosure and / or a pressure regulating unit proposed according to the disclosure.

[0050] It is advantageous if, for the plausibility check, i.e., to check the differential pressures for possible faults, a differential pressure not equal to 0 Pa is present, since measurement tolerances then do not, or at least not substantially, influence the plausibility check.

[0051] To achieve this, the final control element of the gas regulating valve or a safety valve provided upstream of the gas regulating valve is triggered, specifically by means of the control unit, to change the process pressure, so that the change in the process pressure changes the signed differential pressures inversely to one another.

[0052] If the safety valve is closed, the process pressure corresponds specifically to a suction pressure generated by a blower arranged downstream of the gas regulating valve and / or by a mixing device configured specifically as a venturi mixer. Since the safety valve is being closed or is closed, specifically during ventilation of the burner before or after burner operation, that is, for example, during a pre-flushing phase and / or during a post-flushing phase of the gas heater / the gas burner, the plausibility check may be conducted during the ventilation and specifically in the pre-flushing or post-flushing phase.

[0053] If the passage through the safety valve is varied to change the process pressure, even a small differential pressure may be sufficient for plausibility checking. In this context, such a change in the process pressure may occur during the operation of the gas heater / the gas burner, i.e., after the pre-flushing phase or during the burner operation.

[0054] In this context, it is preferably provided that the change in the process pressure exceeds at least a predetermined measurement tolerance of the sensor assemblies, so that measurement tolerances may be substantially neglected for the plausibility check.

[0055] Subsequently, the signed differential pressures ascertained by the sensor assemblies after the change in the process pressure are each compared with a respective target value or threshold value.

[0056] In this regard, as previously explained, the comparison plausibility checks whether a first differential pressure of the two signed differential pressures associated with the first sensor assembly is the differential pressure determined by the first sensor assembly, and / or whether a second differential pressure of the two signed differential pressures associated with the second sensor assembly is the differential pressure determined by the second sensor assembly, and / or whether the process pressure is applied to the first pressure input of the first sensor assembly configured as a differential pressure sensor or to a first pressure sensor of a sensor assembly having at least one pressure sensor, and / or whether the reference pressure is applied to the second pressure input of the first sensor assembly configured as a differential pressure sensor or to a second pressure sensor of a sensor assembly having at least one pressure sensor, and / or whether the reference pressure is applied to the first pressure input of the second sensor assembly configured as a differential pressure sensor or to a first pressure sensor of a sensor assembly having at least one pressure sensor, and / or whether the process pressure is applied to the second pressure input of the second sensor assembly configured as a differential pressure sensor or to a second pressure sensor of a sensor assembly having at least one pressure sensor.

[0057] If it is established that the signed differential pressures are not plausible, i.e., do not have the expected sign or do not have the expected absolute value, the system may indicate a fault, be switched off, or be switched to a safe mode.

[0058] Correspondingly, a development of the method provides that a fault 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.

[0059] The features disclosed above may be used in any combination, as far as this is technically feasible and they do not contradict each other.

[0060] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF DRAWINGS

[0061] Other advantageous developments of the disclosure are characterised in the dependent claims or are presented in further detail below along with the description of the preferred embodiment of the disclosure with reference to the figures. In the drawings:

[0062] FIG. 1 depicts a schematic block diagram of a gas heater;

[0063] FIG. 2 depicts a schematic block diagram of a gas regulating valve;

[0064] FIG. 3 depicts a first pressure diagram for plausibility checking in a first operating mode;

[0065] FIG. 4 depicts a second pressure diagram for plausibility checking in a second operating mode.DETAILED DESCRIPTION

[0066] The figures are schematic by way of example. Like reference numbers in the figures indicate like functional and / or structural features.

[0067] In FIG. 1, a section or part of a gas heater 1, specifically a gas boiler, is shown schematically and by way of example, wherein the gas regulating valve 2 illustrated in FIG. 2 as well as the gas regulating unit 10 contained therein may each be the gas regulating valve 2 and the gas regulating unit 10 according to FIG. 1, however, in principle may also be contemplated independently of the gas heater 1 or built into other installations or devices. Although the components and functions of FIGS. 1 and 2 are described collectively in the present document, what is disclosed with respect to FIG. 2, specifically, may also be contemplated independently of the exemplary embodiment according to FIG. 1.

[0068] FIG. 1 schematically depicts a part or a section of a gas heater 1 and more precisely the schematic construction of a gas-air system of a gas heater 1, wherein a venturi mixer is shown as a mixing apparatus 7, in which air is drawn in from the environment by a blower 8 through an air inlet L at an air pressure p0. In the mixing apparatus 7, the air flowing in and a fuel (gas) flowing in through the fuel supply G are mixed to form a gas-air mixture.

[0069] The gas flowing in from the fuel supply G flows to the mixing apparatus 7 through a safety valve 5 with a final control element 40 adjustable by an actuator 50, a gas regulating valve 2 with a valve or final control element 30 configured, for example, as a proportional valve, as well as a main flow restrictor 6.

[0070] The safety valve 5 or its final control element 40 preferably has a through position and a blocking position between which the actuator 50 may be switched, wherein the passage of the fuel or gas is enabled in the through position and blocked in the blocking position. The safety valve 5 may additionally or alternatively also be manually actuatable or actuatable by hand.

[0071] The gas regulating valve 2 is configured to regulate the volumetric or mass flow of the gas, so that the gas or the flow of the gas through the gas regulating valve 2 to the mixing apparatus 7 is adjustable or regulatable.

[0072] Thus, adjusting or regulating the flow of the gas using the gas regulating valve 2 as well as by means of a main flow restrictor 6 provided, as appropriate, between the gas regulating valve 4 and the mixing apparatus 7, causes the mixing ratio of the gas-air mixture in the mixing apparatus 7 to be regulatable or adjustable.

[0073] The gas-air mixture is further conveyed by the blower 8 into a burner 9 or its combustion chamber, where the combustion of the gas-air mixture takes place.

[0074] To regulate the gas flow or the passage through the gas regulating valve 2, it has a final control element 30, for example configured as a proportional valve, as shown, whose position is adjustable by an actuator 20, specifically configured as a stepper motor, as well as a gas regulating unit 10.

[0075] The gas regulating unit 10 itself is not configured to be fail-safe, but alongside control electronics 13, an actuator interface 14 signalling connected to the control electronics 13, as well as a communication interface 15 signalling connected to the control electronics 13, it comprises two sensor assemblies 11, 12, each configured as a differential pressure sensor 11, 12.

[0076] It is essential for the shown embodiment, on the one hand, that the respective differential pressure p11, p12 is acquired by the respective differential pressure sensor 11, 12 not only as an absolute value (i.e., unsigned), but in each case as signed pressure values or signed differential pressures. In this context, the differential pressures result from, for example, subtracting a pressure applied to each respective second pressure input 11B, 12B from a pressure applied to each respective first pressure input 11A, 12A, so that, depending on the respective applied pressures, signed pressure values may result for the differential pressures.

[0077] On the other hand, it is essential for the shown embodiment that a same pressure, denotable as a process pressure p1, is applied or applicable to the first pressure input 11A of the first differential pressure sensor 11 and to the second pressure input 12B of the second differential pressure sensor 12, as well as a same pressure, denotable as a reference pressure p0, is applied or applicable to the second pressure input 11B of the first differential pressure sensor 11 and to the first pressure input 12A of the second differential pressure sensor 12, so that the differential pressures p11, p12 ascertained by the two differential pressure sensors 11, 12 are mutually inverse.

[0078] As shown in FIGS. 1 and 2, it is provided in the present document that one separate pressure channel each leads to the first pressure input 11A of the first differential pressure sensor 11 and to the second pressure input 12B of the second differential pressure sensor 12 to the measurement point of the process pressure, whereas the pressure channels from the second pressure input 11B of the first differential pressure sensor 11 and from the first pressure input 12A of the second differential pressure sensor 12 to the measurement point of the reference pressure are formed integrally with one another in sections.

[0079] In this context, the process pressure p1 is a gas pressure in the gas regulating valve 2 on the discharge or outflow side of the final control element 30, and the reference pressure p0 is an air pressure at the gas regulating valve 2 or at the air inlet L, which may, however, deviate from the ambient pressure poo.

[0080] While the gas regulating valve 2 itself is not configured to be fail-safe, the gas heater 1 must be operable in a fail-safe manner. For this purpose, the differential pressures p0, p1 are transferred from the gas regulating valve 2 via the communication interface 15 to a control unit 3, which may check on the basis of the absolute values whether a measuring error is present. In the prior art, however, such control units 3 cannot verify whether the differential pressures associated with the first differential pressure sensor 11 and the second differential pressure sensor 12 have actually been measured by the respective differential pressure sensor 11, 12.

[0081] To form a system 4 consisting of the control unit 3 and the gas regulating valve 2 which is fail-safe overall, the signed pressure values are transferred to the control unit 3 from the gas regulating valve 2 or via the communication interface 15 of the gas regulating unit 10.

[0082] Since in normal combustion operation of the gas heater 1, the goal is usually zero-pressure regulation, the process pressure p1 substantially corresponds to the reference pressure p0, so that the differential pressures p11, p12 fluctuate in the range around 0 (e.g., 0 Pa or 0 bar). Due to measurement inaccuracies, in this regard, it is usually not possible to reliably deduce a fault from the respective sign.

[0083] Hence, the control unit 3 is configured to plausibility check the differential pressures p11, p12 in certain operating modes or within the framework of certain methods, i.e., to check for faults, with a pressure diagram according to FIGS. 3 and 4 resulting in each case.

[0084] Since the plausibility check is usually not conductable in a reliable manner during normal combustion operation or burner operation, it is provided according to a first method variant, the pressure curve of which being shown in FIG. 3, that the plausibility check is conducted during or in parallel with ventilation and specifically in a pre-flushing phase, in which the burner 9 or its combustion chamber is flushed or ventilated with air. For this purpose, the safety valve 5 and / or the gas regulating valve 2 is triggered to completely block a gas stream or a gas flow to the mixing apparatus 7 during the ventilation and, herein, in the pre-flushing phase, wherein the blower 8 continues to draw in air, so that a suction pressure of the blower 8 consequently ensues at the process pressure measurement point. As an alternative to the pre-flushing phase, the described method may also be conducted in a post-flushing phase.

[0085] The pressure curve ensuing therefrom is illustrated in FIG. 3, wherein at time T1, the blower 8 is switched on with the safety valve 5 and / or gas regulating valve 2 closed, and at time T2, the closed valves (safety valve 5 and / or gas regulating valve 2) are opened to enable passage.

[0086] Assuming the exemplary curve, during the ventilation and, herein by way of example, in the pre-flushing phase (specifically between times T1 and T2), a signed maximum pressure value of −4 ensues for the first differential pressure p11, and a signed maximum pressure value of +4 ensues for the second differential pressure, these being shown as and assumed to be unitless in the present document.

[0087] Since it is known that p11 results from p1-p0, and p12 results from p0-p1, and due to the ventilation, also that a lower value ensues for p1 than for p1, it may be deduced directly by means of the respective sign whether the values transmitted to the control unit 3 are correctly associated with the differential pressure sensors. In this context, the ratios and necessary assumptions need not necessarily be maintained in the control unit 3. It is sufficient, for example, for a fault to be assumed if p11 during the ventilation or p11 at a certain time during the ventilation or an average value of p11 during the ventilation is >0, and / or if p12 during the ventilation or p12 at a certain time during the ventilation or an average value of p12 during the ventilation is <0.

[0088] Consequently, if the differential pressure p12 is positive and the differential pressure p11 is negative, the differential pressure p12 is correctly associated with the second differential pressure sensor 12, and the differential pressure p11 is correctly associated with the first differential pressure sensor 11, so that the differential pressures or the pressure values have been plausibility checked. If this is not the case, a fault is present, so that correspondingly, a fault message may be output and / or the gas heater 1 may be switched off and / or switched to a safe mode.

[0089] Since this variant only enables a plausibility check during ventilation and, for example, in pre-flushing operation (or in post-flushing operation), it may alternatively or additionally also be provided that, during combustion operation or burner operation, the control unit 3 switches to a plausibility check mode for a short time in which there is no zero-pressure regulation for a short time, but a target pressure difference X of 2, for example, is set, as shown in FIG. 4, wherein other predetermined target pressure values X are also possible which should, however, exceed a measurement tolerance of the differential pressure sensors 11, 12. In the plausibility check mode, deliberate stimulation of the differential pressure sensors 11, 12 occurs for a short time, wherein the plausibility check may occur based on their behaviour or the signed pressure values ascertained in this context.

[0090] Correspondingly, a target differential pressure of 2 may be specified to the control electronics 13 by the control unit 3 via the communication interface 15, so that the control electronics 13 set the final control element 20 via the actuator electronics or actuator interface 14 in such a way that the new target differential pressure X ensues at at least one of the differential pressure sensors 11, 12 or at both of the differential pressure sensors 11, 12 at least for a short time. Subsequently, and specifically insofar as no fault is detected, it is possible to switch directly back to normal combustion operation.

[0091] If the new target differential pressure X of 2, for example, has been reached, it may again be deduced directly whether the signed pressure values are associated with the correct differential pressure sensor 11, 12. In this context, it should be considered that during the ventilation, i.e., herein in the pre-flushing phase, only a suction pressure may ensue for the process pressure, so that consequently, during the ventilation, or herein in the pre-flushing phase, p1<p0 always applies. In the mentioned plausibility check operation or mode, however, it may be freely determined and specified, and adjusted by triggering the final control element 30 of the gas regulating valve 2, whether the passage of the gas is to be increased or reduced, so that, depending on the desired trigger, p1<p0 (negative pressure) or p1>p0 (positive pressure) may apply. In this context, the pressure curve according to FIG. 4 corresponds to the variant of p1>p0, so thatp⁢11=p⁢1-p⁢0>0,andp⁢12=p⁢0-p⁢1<0.

[0092] If, in turn, the differential pressures p11 and p12 do not have the sign nor the target or threshold value previously known and maintained for each case (p1<p0 or p1>p0), a fault is again present, so that again, correspondingly, a fault message may be output and / or the gas heater 1 may be switched off and / or switched to a safe mode.

[0093] The embodiments of the disclosure are not limited to the preferred exemplary embodiments indicated above. Rather, a number of variants are possible, which make use of the described solution in fundamentally different embodiments.

Claims

1. A gas regulating unit for fail-safe regulation of a gas, specifically in a gas heater or a gas burner, comprising:a communication interface, a first sensor assembly, and a second sensor assembly;the first sensor assembly is configured to acquire measured values from which a signed first differential pressure (p11) between a process pressure (p1) of the gas and a reference pressure (p0) is determinable;the second sensor assembly is configured to acquire measured values from which a signed second differential pressure (p12) between the reference pressure (p0) and the process pressure (p1) is determinable, so that the signed first differential pressure (p11) and the signed second differential pressure (p12) are signed mutually inverse differential pressures (p11, p12); andthe communication interface is configured to send the mutually inverse differential pressures (p11, p12) and / or the measured values to an external receiver.

2. The gas regulating unit according to claim 1, wherein the first sensor assembly is a first differential pressure sensor or is a first mass flow sensor or has at least two sensors, each configured as a pressure sensor or as a mass flow sensor, and / orwherein the second sensor assembly is a second differential pressure sensor or is a second mass flow sensor or has at least two sensors, each configured as a pressure sensor or as a mass flow sensor.

3. The gas regulating unit according to claim 1, wherein 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 configured to ascertain a differential pressure (p11, p12) by subtracting a pressure applied to the second pressure input from a pressure applied to the first pressure input;the process pressure (p1) is applied to the first pressure input of the first differential pressure sensor, and the reference pressure (p0) is applied to the second pressure input of the first differential pressure sensor;the reference pressure (p0) is applied to the first pressure input of the second differential pressure sensor, and the process pressure (p1) is applied to the second pressure input of the second differential pressure sensor, so that the differential pressures (p11, p12) ascertained by the two differential pressure sensors (11, 12) are mutually inverse.

4. The gas regulating unit according to claim 1 further comprising:control electronics signalling connected to the first sensor assembly and the second sensor assembly and configured to acquire the mutually inverse differential pressures (p11, p12) or determine them from the measured values.

5. The gas regulating unit according to claim 4 further comprising:an actuator interface for triggering an actuator, specifically a stepper motor, signalling connected to the control electronics or formed integrally with the control electronics.

6. The gas regulating unit according to claim 4, wherein the communication interface is signalling connected to the control electronics or is formed integrally with the control electronics,the communication interface is specifically configured to receive control signals.

7. A gas regulating valve for fail-safe regulation of a gas in a gas heater or a gas burner comprising:a gas regulating unit according to claim 1 and a final control element for adjusting passage of a gas flowing from an inflow side to an outflow side of the gas regulating valve; andthe process pressure (p1) is the pressure of the gas on the outflow side of the gas regulating valve.

8. The gas regulating valve according to claim 7, wherein the reference pressure (p0) is an ambient pressure at the gas regulating unit and / or the gas regulating valve.

9. The gas regulating valve according to claim 7 further comprising:an actuator signalling connected to the actuator interface of the gas regulating unit and configured to adjust the final control element for adjusting the passage.

10. The gas regulating valve according to claim 9, wherein the control electronics are configured to adjust the final control element for adjusting the passage by triggering the actuator until at least one of the differential pressures (p11, p12) and / or measured values corresponds to a predetermined value and / or is 0 Pa.

11. A system for fail-safe regulation of a gas in a gas heater or a gas burner comprising:a control unit for regulating combustion and a gas regulating valve according to claim 7;the control unit is signalling connected to the communication interface of the gas regulating unit as an external receiver and is configured to receive and process the mutually inverse differential pressures (p11, p12) and / or to send control signals to the communication interface.

12. The system according to claim 11, wherein the control unit is configured toplausibility check the mutually inverse differential pressures (p11, p12) by comparing the mutually inverse differential pressures (p11, p12) with target values or threshold values stored in the control unit,and / or plausibility check the mutually inverse differential pressures (p11, p12) by comparing the absolute values of the mutually inverse differential pressures (p11, p12) with one another,and / or plausibility check the application of the process pressure (p1) and the reference pressure (p0) to the sensor assemblies (11, 12).

13. A method for plausibility checking differential pressures (p11, p12) acquired with a system for fail-safe pressure regulation according to claim 11 comprising:triggering the final control element of the gas regulating valve or a safety valve, provided upstream of the gas regulating valve, to change the process pressure (p1), so that the change in the process pressure (p1) changes the first differential pressure (p11) and the second differential pressure (p12) inversely to one another;comparing, after their change, the mutually inverse differential pressures (p11, p12) with a respective target value or threshold value, and by means of the comparison;checking whether the first differential pressure (p11) associated with the first sensor assembly is the differential pressure acquired from the first sensor assembly, and / or whether the second differential pressure (p12) associated with the second sensor assembly is the differential pressure acquired from the second sensor assembly, and / or whether the process pressure (p1) is applied to the first sensor assembly as intended, and / or whether the reference pressure (p0) is applied to the first sensor assembly as intended, and / or whether the reference pressure (p0) is applied to the second sensor assembly as intended, and / or whether the process pressure (p1) is applied to the second sensor assembly as intended.

14. The method according to claim 13, wherein a fault is detected and output if the mutually inverse differential pressures (p11, p12) do not correspond to the respective target values or do not reach the respective threshold values.

Images