DE102023112190A1 - Method for characterizing a gas valve of a heating device, method for operating a heating device, heating device and computer program - Google Patents

Abstract

A method is proposed for characterising a gas valve (5) of a heating device (1) which can be controlled by a stepper motor, which method comprises at least the following steps:
a) detecting an opening width and/or a volume flow flowing through the gas valve (5) for different stepper motor positions M _{Pos_akt} (19),
b) comparing the opening widths and/or volume flows recorded in step a) with corresponding opening widths or volume flows of a nominal gas valve for the different stepper motor positions M _{Pos_akt} (19) and determining a transfer function (17) from a stepper motor position M _{Pos_Nom} (18) of the nominal gas valve to a stepper motor position M _{Pos_akt} (19) of the gas valve (5). In addition, a method for operating a heating device (1) with a gas valve (5) characterized according to the proposed method and a heating device (1) are proposed.

Description

The invention relates to a method for characterizing a gas valve, a method for operating a heating device, a heating device and a computer program.

Gas valves are used in particular in heaters with an electronic gas-air connection, the opening width of which can be adjusted using a stepper motor. Due to component tolerances, for example, the volume flows of such gas valves differ from one another when the stepper motor is in the same position. Therefore, according to the state of the art, an offset value in the range of the ignition volume flow is set in the heater before installation. This ensures that the heater can be started up safely.

However, the heater or combustion control system does not have any information about the actual mass flow of fuel gas that can flow through the gas valve at a defined stepper motor position. In particular, when the stepper motor positions deviate from the ignition volume flow, significant differences can occur between the actual flowing mass flow of fuel gas and the mass flow of fuel gas assumed by the combustion control system.

The EP 2 489 935 A2 proposes a control of a gas valve operated by a stepper motor, in which a control detects a combustion signal and the control sets a stepper motor position according to the combustion signal and detects a deviation from the intended stepper motor position. Disadvantages are that the combustion signal can also be faulty or subject to sensor drift, and as a result an incorrect gas flow can be added.

The object of the present invention is to at least partially alleviate the problems described with reference to the prior art and, in particular, to propose a method for characterizing a gas valve of a heating device, a method for operating a heating device and a heating device that enables precise control of the mass flow of fuel flowing through the gas valve. The invention should also be easy to implement and at least partially retrofittable to existing systems.

These objects are achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically reasonable manner and define further embodiments of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

1. a) Erfassen jeweils einer Öffnungsweite und/ oder eines das Gasventil durchströmenden Volumenstromes für unterschiedliche, einzustellende, Schrittmotorpositionen, und
2. b) Vergleichen der in Schritt a) erfassten Öffnungsweiten und/ oder Volumenströme mit entsprechenden Öffnungsweiten oder Volumenströmen eines nominellen Gasventils für die unterschiedlichen Schrittmotorpositionen M_{Pos_akt} und Bestimmen einer Übertragungsfunktion von einer Schrittmotorposition M_{Pos_Nom} des nominellen Gasventils zu einer Schrittmotorposition M_{Pos_akt} des Gasventils.

A method for characterizing a gas valve of a heating device that can be controlled with a stepper motor contributes to this. The method comprises at least the following steps:

1. a) Detecting an opening width and/or a volume flow through the gas valve for different, adjustable, stepper motor positions, and
2. b) Comparing the opening widths and/or volume flows recorded in step a) with corresponding opening widths or volume flows of a nominal gas valve for the different stepper motor positions M _{Pos_akt} and determining a transfer function from a stepper motor position M _{Pos_Nom} of the nominal gas valve to a stepper motor position M _{Pos_akt} of the gas valve.

In a regular procedure, steps a) and b) can be carried out at least once in the order given. In particular, the procedure can be carried out prior to installation or assembly of the gas valve in a heating device.

The heater can be a gas heater. This can include a conveying device designed as a fan, which can convey a mass flow (or volume flow) of combustion air or a combustion mixture of fuel (combustion gas) and combustion air. The combustion air can be sucked in via a combustion air supply. A gas valve is designed to add a mass flow (or volume flow) of combustion gas corresponding to a predetermined combustion air ratio to the sucked-in mass flow of combustion air. The combustion mixture formed can then be fed to a burner of the heater via a mixture channel and burned there. The heater can form a pneumatic or, in particular, an electronic gas-air connection for this purpose.

The gas valve can control the volume or mass flow of fuel gas flowing through it by its opening width, whereby the opening width can be adjusted by an electrically controlled stepper motor. The stepper motor can be connected to a control and regulation device, for example. of the heater. To regulate combustion, the control unit can add a volume or mass flow of combustion gas, specified by the combustion air ratio to be set, to a volume or mass flow of combustion air (detected or determined based on the power or speed of the conveyor). To do this, the control unit can set a stepper motor position of the gas valve that corresponds to the mass flow of combustion gas to be added.

The proposed method provides a simple way of assigning a volume or mass flow flowing through a gas valve to the set stepper motor position. In step a), an opening width and/or a volume or mass flow flowing through the gas valve can be recorded for different stepper motor positions that are set when performing step a). The opening width (also referred to as the opening position) can indicate the flow cross-section of the gas valve available for the gas flow through the gas valve and thus enable a conclusion to be drawn about a volume or mass flow flowing through the gas valve. The volume or mass flow flowing through the gas valve can be specified for a defined pressure of the gas supply connected to the gas valve in order to enable the recorded values to be compared. In simple terms, in step a), stepper motor positions can be set on the gas valve and the resulting opening width and/or the resulting volume or mass flow flowing through the gas valve can be recorded or measured. Step a) can be carried out in particular prior to installation of the gas valve in a heating appliance.

According to step a), an opening width and/or a volume flow through the gas valve can be detected for different stepper motor positions to be set.

According to one embodiment, step a) can be carried out for all stepper motor positions that are relevant for the operation of the gas valve or the heater. Relevant stepper motor positions are characterized in that they are set during regular operation of the heater.

Alternatively, step a) can also be carried out for the entire range of opening width that can be adjusted on the gas valve and thus for all possible or the entire available range of all stepper motor positions.

The stepper motor positions to be set in step a) can be set as a set of discrete values or as a (ramp) function. In particular, step a) can be carried out by continuously running through the entire range of stepper motor positions to be set once.

According to step b), the opening widths and/or volume flows recorded in step a) can be compared with corresponding opening widths or volume flows of a nominal gas valve for the different stepper motor positions M _{Pos_akt} and a transfer function can be determined from a stepper motor position M _{Pos_Nom} of the nominal gas valve to a stepper motor position M _{Pos_akt} of the gas valve.

The nominal gas valve can be understood as a tolerance-free, ideal gas valve. An assignment of a stepper motor position M _{Pos_Nom} of the nominal gas valve to a volume flow is often stored in the combustion control of a heater. A transfer function determined in step b) from an opening position M _{Pos_Nom} of a nominal gas valve to an opening position of the gas valve to be installed or installed in the heater enables the stepper motor position of the gas valve to be installed to be determined with knowledge of the stepper motor position of the nominal gas valve and the transfer function. The stepper motor position determined in this way is advantageously linked to a corresponding volume flow of fuel gas by a method proposed here. It is noted that the volume flow of fuel gas also depends on the pressure in a supply line of the fuel gas to the gas valve.

According to one embodiment, the transfer function determined in step b) can be stored in a memory of the gas valve. For example, the process can be carried out after the gas valve has been manufactured and the gas valve can be installed without any further preparations when assembling the heater. A control and regulating device of the heater can read the transfer function from the gas valve's memory in order to operate it and use it to operate the gas valve.

In this context, it should be noted that the terms volume flow and mass flow used here are understood as synonyms. A volume flow can therefore easily be converted into a mass flow and vice versa, given knowledge of the density of the flowing medium. If necessary, a conversion can also be carried out approximately using a factor.

According to a further aspect, a method for operating a heater is also proposed, wherein a transfer function has been determined according to a method proposed here and a stepper motor position to be controlled of the gas valve to be installed in the heater is determined on the basis of a stepper motor position of the nominal gas valve specified for the operating point to be controlled and the transfer function.

The method can be carried out in particular on a control unit of the heater. For this purpose, the transfer function can be stored in a memory of the control unit or the gas valve.

According to a further aspect, a computer program is also proposed which is set up to (at least partially) carry out a method presented here. For example, a method proposed here for operating the heater can be carried out on a heater proposed here, in particular its regulating and control device. It is also possible to carry out a method proposed here for characterizing a gas valve using a computer program. For this purpose, a computer can record or measure an opening width of the gas valve or a volume flow through the gas valve for various or all stepper motor positions and determine the transfer function.

The computer program (product) may include instructions which, when executed by a computer, cause the computer to carry out a method proposed here.

According to a further aspect, a computer-readable storage medium is also proposed on which a computer program proposed here is stored.

The details, features and advantageous embodiments discussed in connection with the methods can also occur in the computer program, the heating device, the computer program and/or the computer-readable storage medium presented here and vice versa. In this respect, reference is made in full to the statements there for a more detailed characterization of the features.

A method for characterizing a gas valve, a method for operating a heating device, a heating device and a computer program are therefore specified here, which at least partially solve the problems described with reference to the prior art. In particular, the method for characterizing a gas valve, the method for operating a heating device and the heating device contribute to enabling a very precise control of a gas valve and thus enabling a precise setting of the combustion air ratio of a heating device. In addition, the invention can reduce the effort involved in assembling a heating device or installing a gas valve. In this respect, the invention can also be used excellently in the context of replacing a defective gas valve and simplifying this process.

In addition, the invention can be implemented with no or only very minor structural changes to a heating device.

• 1: ein hier vorgeschlagenes Heizgerät, und
• 2 und 3: Parameterverläufe, die sich bei Durchführung eines hier vorgeschlagenen Verfahrens einstellen können.

The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description. In particular, it should be noted that the figures and in particular the size relationships shown are only schematic. They show:

• 1 : a heater proposed here, and
• 2 and 3 : Parameter curves that can occur when carrying out a procedure proposed here.

1 shows, by way of example and schematically, a heating device 1 proposed here. This can suck in combustion air through a conveyor device 2 via a combustion air supply 4 and, via a gas valve 5, add a gas from a gas supply 13, for example natural gas or hydrogen, to the mass flow of combustion air sucked in through the combustion air supply 4. The combustion mixture 14 of fuel and combustion air can now be fed via a mixture channel 11 to a burner 3 arranged in a combustion chamber 8. The combustion products can be fed from the combustion chamber 8 via an exhaust pipe 9 to an exhaust system 10. The burner 3 is attached to a burner door 6, in which a flame monitor 12 can also be arranged, for example a UV sensor. The UV sensor can be arranged outside the combustion chamber 8, protected from the high temperatures near the burner 3. The heating device 1 can also have a regulating and control device 7.

2 shows an example and schematically a connection between the steps a) of the method presented here for characterizing a gas valve 5 (to be installed). The diagram shows the volume flow V̇, for example given in liters per hour, and the corresponding stepper motor position M _Pos of the gas valve 5 to be installed once as a curve 16 for a nominal gas valve and as a curve 15 for the gas valve 5 to be installed. For a specific volume flow 20, a first stepper motor position M _{Pos_Nom} 18 for the nominal gas valve and a second stepper motor position M _{Pos_akt} 18 for the gas valve 5 to be installed can result, which differ from one another due to manufacturing or component tolerances.

3 shows, by way of example and schematically, a transfer function 17 which can result from the curve 15 for the nominal gas valve and the curve 16 for the gas valve 5 to be installed. The transfer function 17 enables an assignment of a stepper motor position M _{Pos_Nom} 18 of the nominal gas valve, which can be specified for an operating point to be approached, to a stepper motor position M _{Pos_akt} 19 of the gas valve 5 to be installed. In other words, an assignment of a stepper motor position M _{Pos_Nom} 18 of the nominal gas valve corresponding to a specified or set combustion air ratio to a stepper motor position M _{Pos_akt} 19 of the gas valve 5 to be installed is made possible, thus enabling an exact setting of the combustion air ratio.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, sizes or processes, and in particular do not necessarily specify a dependency and/or sequence of these objects, sizes or processes. If a dependency and/or sequence is required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described design. If a component can occur multiple times ("at least one"), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

list of reference symbols

1

heater

2

conveyor system

3

burner

4

combustion air supply

5

gas valve

6

burner door

7

control and regulation device

8

combustion chamber

9

exhaust duct

10

exhaust system

11

mixture channel

12

flame monitoring

13

gas supply

14

combustion mixture

15

Gas valve to be installed

16

nominal gas valve course

17

transfer function

18

stepper motor position nominal gas valve

19

stepper motor position gas valve to be installed

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 2 489 935 A2 [0004]

Claims (8)

Method for characterizing a gas valve (5) of a heater (1) that can be controlled by a stepper motor, comprising at least the following steps: a) detecting an opening width and/or a volume flow flowing through the gas valve (5) for respectively different stepper motor positions M _{Pos_akt} (19), b) comparing the opening widths and/or volume flows detected in step a) with corresponding opening widths or volume flows of a nominal gas valve for the different stepper motor positions M _{Pos_akt} (19) and determining a transfer function (17) from a stepper motor position M _{Pos_Nom} (18) of the nominal gas valve to a stepper motor position M _{Pos_akt} (19) of the gas valve (5). procedure according to claim 1 , wherein in step a) opening positions and/or volume flows for all stepper motor positions M _{Pos_akt} (19) that are relevant for the operation of the heater (1) are recorded. Method according to one of the preceding claims, wherein the transfer function (17) determined in step b) assigns a stepper motor position M _{Pos_Nom} (18) of the nominal gas valve to a stepper motor position M _{Pos_act} (19) of the gas valve (5) for a predetermined volume flow. Method according to one of the preceding claims, wherein steps a) and b) are carried out before installing the gas valve (5) in the heater (1). Method for operating a heater (1), wherein a transfer function (17) has been determined according to a method according to one of the preceding claims and an opening width to be controlled or a volume flow of fuel gas of the gas valve (5) of the heater (1) to be set is determined on the basis of a stepper motor position M _{Pos_Nom} (18) of the nominal gas valve predetermined for the operating point to be controlled and the transfer function (17). Method for operating a heating device (1) according to claim 5 , wherein the transfer function (17) is stored on a regulating and control device (7) of the heater (1). Heating device (1) comprising a gas valve (5) which can be controlled by a stepper motor, a regulating and control device (7) and means for carrying out a method according to one of the Claims 5 or 6 . Computer program comprising commands that control a heating device (1) according to claim 7 to initiate proceedings under claim 5 or 6 to execute.

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