Method for the diagnose of a gas concentration sensor, gas concentration sensor, computer program, and computer-readable medium

Abstract

The invention relates to a method for the diagnosis of a gas concentration sensor on the basis of the detected temperature distribution. The invention further relates to a gas concentration sensor, to a computer program product and to a computer-readable medium.

Description

[0001] Description

[0002] Method for diagnosing a gas concentration sensor, gas concentration sensor, computer program and computer-readable medium

[0003] Technical area

[0004] The invention relates to a method for diagnosing a gas concentration sensor, a gas concentration sensor, a computer program, and a computer-readable medium. The gas concentration sensor is, in particular, a gas concentration sensor designed to determine the gas concentration of a gas as a function of the thermal conductivity and / or the heat capacity of the gas.

[0005] State of the art

[0006] The documents US 10 112 486 B2, DE 10 2019 204 284 A1 , JP 2019 128 182 A, US 9 027 386 B2 and US 2009 00 61 261 A1 disclose gas sensors.

[0007] A particular disadvantage of the prior art devices is that a diagnosis of such gas sensors is only possible with a correspondingly high additional technical effort for diagnostic tools.

[0008] Description of the invention, task, solution, advantages

[0009] Therefore, the object of the present invention is to create a method that is particularly characterized by its simple and / or cost-effective implementation. Alternatively or additionally, the object of the present invention is to provide an alternative method.

[0010] Further objects of the invention are to provide a gas concentration sensor, a computer program, and a computer-readable medium. The object regarding the method is achieved by a method having the features of claim 1.

[0011] One embodiment of the invention relates to a method for diagnosing a gas concentration sensor. The gas concentration sensor is designed to determine the gas concentration of a gas as a function of the thermal conductivity and / or the heat capacity of the gas. The gas concentration sensor comprises a heater and a temperature sensor array, the temperature sensor array having multiple regions with at least one temperature sensor per region. The method comprises the steps of generating a heat flow using the heater, determining a temperature distribution on the temperature sensor array using the temperature sensors of the respective regions, and diagnosing the gas concentration sensor as a function of the determined temperature distribution. For this purpose, it is preferred if the heater influences or can influence the temperature or temperature distribution using the heat flow it generates.

[0012] This makes it possible to perform a cost-effective and simple diagnosis of the gas concentration sensor. In other words, a homogeneous temperature distribution is assumed to indicate a correctly functioning gas concentration sensor, whereas an inhomogeneous temperature distribution is assumed to indicate a defective gas concentration sensor. Instead of assuming a defective gas concentration sensor, it is alternatively conceivable to assume a source of interference. Such a source of interference could be, for example, a water droplet or a dirt particle on the temperature sensor field or in the immediate vicinity of one of the temperature sensors. A water droplet can form, for example, due to condensation.

[0013] Such gas concentration sensors are based in particular on the fact that they make use of the thermal conductivity and / or the heat capacity of the gas or gas mixture to be measured in order to determine the concentration of, for example, hydrogen or nitrogen within the gas or gas mixture. To do this, for example, the heater is activated and its surroundings are heated up. The time that elapses until a certain temperature can be determined using the temperature sensor is a characteristic value for the gas concentration of, for example, hydrogen or nitrogen within the gas or gas mixture to be measured. Alternatively, it is conceivable to use the temperature determined using the temperature sensor as a characteristic value for the gas concentration. Both characteristic values ​​depend on the thermal conductivity and / or the heat capacity of the gas or gas mixture.The thermal conductivity and / or heat capacity of the gas or gas mixture, in turn, depends on the gas concentration, for example, the concentration of hydrogen or nitrogen within the gas or gas mixture. In other words, the gas concentration can be determined in this way.

[0014] It is particularly advantageous if the gas concentration sensor is designed to determine the gas concentration of hydrogen and / or nitrogen of a gas or gas mixture or of a corresponding gas flow or gas mixture flow.

[0015] The gas is preferably a gas mixture or a corresponding flow, which in particular comprises hydrogen and / or nitrogen.

[0016] The determination is preferably a measurement using the gas concentration sensor.

[0017] It is preferred if several temperature sensors or a large number of temperature sensors are provided per zone. This allows a higher resolution of the temperature distribution to be determined using the temperature sensors. Furthermore, it is preferred if the same number of temperature sensors are provided per zone. This allows the temperature distribution across the temperature sensor field to be determined evenly. Furthermore, it is preferred if the heater is an electric heater or an electric heating element. Preferably, it is a resistance heating element or a PTC heating element. The temperature measurements are preferably available as electronic signals, for example as analog or digital signals. Such a signal preferably corresponds to a temperature value in Kelvin or degrees Celsius.

[0018] A further embodiment is characterized in that the method comprises determining a first temperature measurement value using a temperature sensor in a first region, determining a second temperature measurement value using a temperature sensor in a second region, determining a temperature measurement difference from the determined temperature measurement values, and determining the temperature distribution as a function of the temperature measurement difference. In other words, the basic idea underlying the method is to compare the prevailing temperature distribution with the determined temperature distribution.

[0019] It is also preferable if the temperature measurements are available as absolute values ​​or differential values. A differential value is understood in particular as the difference from a reference value. The reference value is preferably the temperature of the heater or the ambient temperature of the gas concentration sensor.

[0020] Furthermore, it is advantageous if the temperature measurement difference is the difference between the determined temperature measurement values.

[0021] A further embodiment is characterized in that the method comprises determining a malfunction or a source of interference in the gas concentration sensor when the determined temperature measurement difference exceeds a predetermined threshold. Alternatively or additionally, falling below the temperature measurement difference or a further temperature measurement difference can lead to the detection of a malfunction. The temperature measurement difference is preferably an absolute value.

[0022] It is also preferable to determine the correct functioning of the gas concentration sensor when the measured temperature difference equals or is below the threshold. Alternatively, or additionally, in such a case, it can be determined that no sources of interference are present.

[0023] Preferably, the threshold value for the temperature measurement difference is a maximum of 15%, 10%, 5%, 3%, 1%, 0.05% or 0.01% of the lowest or highest temperature measurement in the temperature unit Kelvin, which is used to determine the temperature measurement difference.

[0024] A further embodiment is characterized in that the threshold value depends on the position of the temperature sensors relative to one another and / or the position of the temperature sensors relative to the heater and / or the distance of the temperature sensors relative to the heater and / or the distance of the temperature sensors relative to one another. Such a dependency is particularly necessary if the temperature sensors used to determine the temperature measurement values ​​and the resulting temperature measurement difference are positioned or spaced unevenly from the heater.

[0025] Preferably, the areas and / or the temperature sensors of the areas are arranged in such a way that they determine the same temperature measurement values ​​and thus a uniform temperature distribution when the temperature distribution is uniform.

[0026] A further embodiment is characterized in that a diagnostic signal is generated depending on the determined temperature distribution. Such a diagnostic signal is preferably present as an electronic signal, for example as an analog or digital signal. The diagnostic signal is preferably forwarded via a signal line to a control unit or an evaluation unit, which may be part of a control unit. Such a control unit or such an evaluation unit is capable of generating an error message using the received diagnostic signal. Such an error message can, for example, be stored on or in the control unit and read out at a later time, for example during an inspection or as part of a repair measure.

[0027] It is also preferable if the diagnostic signal includes information about the malfunction of the gas concentration sensor.

[0028] Furthermore, it is advantageous if the diagnostic signal is only generated when the measured temperature difference exceeds the specified threshold. In other words, in such a case, a diagnostic signal is only generated when a malfunction or a source of interference in the gas concentration sensor is detected. This is particularly helpful because it can generally be assumed that the gas concentration sensor is functioning correctly.

[0029] A further embodiment is characterized in that a cleaning method for cleaning the gas concentration sensor is initiated when the determined temperature measurement difference exceeds one, the other, or a further predetermined threshold. In other words, a cleaning method for cleaning the gas concentration sensor is started when a malfunction of the gas concentration sensor or a source of interference in the gas concentration sensor is detected. Such a cleaning method is preferably a method that includes operating the heater, preferably at maximum heating power and / or for a predetermined period of time. This allows water droplets on the temperature sensor field to evaporate or dirt particles to be burned off, which may be the cause of the malfunction of the gas concentration sensor.Such a cleaning process is preferably initialized by a control unit. It is particularly advantageous for the control unit to initialize the cleaning process in response to the diagnostic signal.

[0030] A further embodiment is characterized in that the temperature sensors are designed as thermoelectric temperature sensors. Thus, the temperature sensors can output an electronic signal, for example, an analog signal or a digital signal, depending on the temperature at the temperature sensor. These are, for example, temperature sensors that comprise resistance thermometers or thermal elements.

[0031] A further embodiment is characterized in that the temperature sensor field is arranged in a temperature sensor field plane, wherein the heater is cut by a subdivision plane which runs perpendicular to the temperature sensor field plane, wherein the regions of the temperature sensor field plane are arranged on the one hand and the subdivision plane on the other hand.

[0032] Preferably, the heater and / or the regions and / or the temperature sensors are arranged such that, during the generation of a heat flow by means of the heater on the one hand and the subdivision level on the other hand, a uniform temperature distribution occurs and / or can be determined. For this purpose, it is particularly advantageous if the heater is designed symmetrically to the subdivision level.

[0033] In case further subdivision levels are provided, this subdivision level is the first subdivision level.

[0034] A further embodiment is characterized in that the heater is cut by a further subdivision plane, which runs perpendicular to the temperature sensor field plane and perpendicular to the first subdivision plane, wherein the regions of the temperature sensor field plane are arranged on the one hand and the further subdivision plane on the other. Preferably, the heater and / or the regions and / or the temperature sensors are arranged such that a uniform temperature distribution occurs and / or can be determined during the generation of a heat flow by means of the heater on the one hand and the further subdivision plane on the other. For this purpose, it is particularly advantageous if the heater is designed symmetrically to the further subdivision plane.

[0035] A further embodiment is characterized in that the gas or the gas mixture flows in the extension direction of the subdivision plane or in the extension direction of the first subdivision plane along the heater and / or the temperature sensor field.

[0036] Advantageously, the first subdivision plane or planes forms a plane of symmetry of the flow profile of a gas stream of the gas or of the gas mixture stream of the gas mixture. This ensures a uniform temperature distribution on both sides of this subdivision plane.

[0037] A further embodiment is characterized in that the first region is arranged on the one hand on the first subdivision level or levels, and the second region is arranged on the other hand on the first subdivision level or levels.

[0038] A further embodiment is characterized in that the first and second regions are arranged on the same side of the second subdivision plane. Preferably, the first and second regions are arranged on a side of the subdivision plane facing away from the flow direction of the gas or gas mixture. This ensures that a diagnosis of the gas concentration sensor is possible even in the case of strong flow.

[0039] A further embodiment is characterized in that the first and second regions are two regions separated from each other by at least one subdivision level. In other words, in this embodiment, it is possible for the first region to be separated from the second region by the subdivision level, by the first subdivision level, by the second subdivision level, or by both the first and second subdivision levels.

[0040] In this embodiment, the gas concentration sensor is preferably arranged such that the gas concentration of the gas or gas mixture is determined largely statically, i.e., without any significant relative movement of the gas or gas mixture to the heater and / or the temperature sensor field plane. This is possible, for example, if the gas concentration sensor is arranged outside a gas channel through which the gas or gas mixture flows and / or is fluidically connected to the gas channel via a rest chamber.

[0041] The object regarding the gas concentration sensor is achieved by providing a gas concentration sensor with a heater, a temperature sensor array comprising a plurality of regions, each region comprising at least one temperature sensor, and means adapted to carry out the steps of the method. The method is preferably the method according to the invention.

[0042] It is also preferable if the gas concentration sensor comprises further features that have been mentioned with regard to the method described above.

[0043] Furthermore, it is advantageous if the gas concentration sensor is fluidically coupled to a gas channel.

[0044] Furthermore, it is advantageous if the gas concentration sensor or the gas concentration sensor with the gas channel is provided as part of a fuel cell system. Furthermore, it is conceivable to provide a vehicle or a stationary power generation plant with such a fuel cell system.

[0045] The problem regarding the computer program is solved by providing a computer program comprising instructions that cause the gas concentration sensor to execute the method steps. The gas concentration sensor is preferably the gas concentration sensor according to the invention.

[0046] The problem regarding the computer-readable medium is solved by providing a computer-readable medium on which the computer program is stored. The computer-readable medium can be a volatile or permanent memory. The computer program is preferably the computer program according to the invention.

[0047] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures.

[0048] Short description of the drawings

[0049] The invention is explained in detail below using exemplary embodiments with reference to the drawings. In the drawings:

[0050] Fig. 1 a motor vehicle,

[0051] Fig. 2 shows an embodiment of the method according to the invention,

[0052] Fig. 3 a representation of three levels, and

[0053] Fig. 4 shows a gas concentration sensor according to the invention.

[0054] Preferred embodiment of the invention

[0055] Figure 1 shows a motor vehicle 1 with a fuel cell system 2, a gas concentration sensor 3 according to the invention as part of the fuel cell system 2 and a control unit 4 coupled to the gas concentration sensor 3. Alternatively, it is conceivable to use such a fuel cell system 2 with the associated gas concentration sensor 3 and the control unit 4 in a stationary energy generation plant.

[0056] Figure 2 shows an embodiment of the method according to the invention. First, the method is started A. Then, a heat flow B is generated by means of a heater. In response to this, a temperature distribution C is determined on a temperature sensor array. This determination comprises determining temperature measured values ​​from different areas of the temperature sensor array. Subsequently, a diagnosis D is performed, which includes determining a malfunction or a source of interference in a gas concentration sensor on which the method is being carried out if a temperature measured value difference determined from the temperature measured values ​​exceeds a predetermined threshold. If no malfunction or source of interference is determined, the method is restarted, preferably with a time delay at regular intervals.Alternatively, it is conceivable to carry out the method when starting up a fuel cell system to which the gas concentration sensor with which the method is carried out belongs. If a malfunction or a source of interference is detected, this information can be stored E on a storage medium which can, for example, belong to a control unit. Additionally or alternatively, a cleaning method F is initialized. The cleaning method can, for example, be a targeted heating of the gas concentration sensor by means of the heater. In this way, dirt particles or water droplets on the temperature sensor field can be removed. Following the cleaning method, the method according to the invention is started again and repeated until the source of interference or the malfunction has been eliminated.

[0057] Figure 3 shows three mutually perpendicular planes TFE, UE1, UE2. A temperature sensor field plane TFE extends in the X-Y plane, while a first subdivision plane UE1 extends in the X-Z plane, and a further subdivision plane UE2 extends in the YZ plane. These planes TFE, UE1, UE2 serve to better understand Figure 4. Figure 4 shows an embodiment of the gas concentration sensor 3 according to the invention. It shows a view perpendicular to the temperature sensor field plane from Figure 3. A temperature sensor field 7 can be seen, which extends in the temperature sensor field plane.The two subdivision planes in Figure 3, whose course is indicated in Figure 4 by the X-axis and the Y-axis, intersect a heater 5 of the gas concentration sensor 3 and divide the temperature sensor field 7 of the gas concentration sensor 3 into four regions 6a to 6d, each of which has a temperature sensor 8a to 8d. The heater 5 is arranged symmetrically to the two subdivision planes in Figure 3 to ensure a uniform temperature distribution. The heater 5 is an electric PTC heater. During application of the method according to the invention using this gas concentration sensor 3, the gas or gas mixture flows laminarly in the direction of extension of the X-axis. In other words, a flow profile 9 is created that is largely symmetrical to the first subdivision plane.This results in a uniform temperature distribution across the temperature sensor array 7, which can be determined, for example, using the two temperature sensors 8a and 8b of the two areas 6a and 6b. If these two temperature sensors 8a and 8b determine different temperature measurement values ​​and a resulting temperature measurement difference exceeds a predetermined threshold, a malfunction or a source of interference in the gas concentration sensor is detected according to the invention.

[0058] The different features of the individual embodiments can also be combined with each other.

[0059] The embodiments of Figures 1 to 4 are not limiting in nature and serve to clarify the inventive concept. List of reference symbols

[0060] 1 motor vehicle

[0061] 2 Hydrogen system

[0062] 3 Gas concentration sensor

[0063] 4 Control unit

[0064] 5 heaters

[0065] 6a - 6d areas

[0066] 7 Temperature sensor field

[0067] 8a - 8d Temperature sensor

[0068] 9 Flow profile

[0069] UE1 first subdivision level

[0070] UE2 further subdivision level

[0071] TFE temperature sensor field level

[0072] A Start

[0073] B Generating a heat flow

[0074] C Determining a temperature distribution

[0075] D Diagnosis

[0076] E Save

[0077] F Initializing a cleaning procedure

Claims

Patent claims 1 . A method for diagnosing a gas concentration sensor, wherein the gas concentration sensor is designed to determine the gas concentration of a gas as a function of the thermal conductivity and / or the heat capacity of the gas, wherein the gas concentration sensor comprises a heater and a temperature sensor field, wherein the temperature sensor field comprises a plurality of areas with at least one temperature sensor per area, comprising the steps: - generating a heat flow by means of the heater, - Determining a temperature distribution on the temperature sensor field using the temperature sensors of the respective areas, and - Diagnosing the gas concentration sensor depending on the determined temperature distribution.

2. Method according to claim 1, wherein the method comprises the following further method steps: - Determining a first temperature measurement value by means of a temperature sensor of a first area, - Determining a second temperature measurement value using a temperature sensor of a second area, - Determining a temperature measurement difference from the determined temperature measurements, and - Determine the temperature distribution depending on the temperature measurement difference.

3. A method according to claim 2, wherein the method comprises the following further method step: - Determine a malfunction or a source of interference of the gas concentration sensor when the measured temperature difference exceeds a specified threshold.

4. The method according to claim 3, wherein the threshold value is dependent on the position of the temperature sensors relative to one another and / or the position of the temperature sensors relative to the heater and / or the distance of the temperature sensors relative to the heater and / or the distance of the temperature sensors relative to one another.

5. Method according to one of the preceding claims, wherein a diagnostic signal is generated as a function of the determined temperature distribution.

6. The method according to any one of claims 3 to 5, wherein a cleaning method for cleaning the gas concentration sensor is initialized when the determined temperature measurement value difference exceeds one, the or another predetermined threshold value.

7. Method according to one of the preceding claims, wherein the temperature sensors are designed as thermoelectric temperature sensors.

8. Method according to one of the preceding claims, wherein the temperature sensor field is arranged in a temperature sensor field plane, wherein the heater is cut by a subdivision plane which runs perpendicular to the temperature sensor field plane, wherein the regions of the temperature sensor field plane are arranged on the one hand and on the other hand of the subdivision plane.

9. The method according to claim 8, wherein the heater is cut by a further subdivision plane which is perpendicular to the temperature sensor field plane and perpendicular to the first subdivision plane, wherein the regions of the temperature sensor field plane are arranged on the one hand and the further subdivision plane on the other hand.

10. The method according to claim 8 or 9, wherein the gas flows in the extension direction of the subdivision plane or in the extension direction of the first subdivision plane along the heater and / or the temperature sensor field.

11. Method according to claim 10, wherein the first region is arranged on the one hand at the first subdivision level, wherein the second region is arranged on the other hand at the first subdivision level.

12. The method according to claim 11, wherein the first and second regions are arranged on the same side of the second subdivision plane.

13. The method according to any one of claims 8 to 11, wherein the first and second regions are two regions separated from one another by at least one subdivision plane.

14. A gas concentration sensor comprising a heater, a temperature sensor array comprising a plurality of regions, each region comprising at least one temperature sensor, and means adapted to carry out the steps of the method according to any one of the preceding claims.

15. A computer program comprising instructions that cause the device of claim 14 to carry out the method steps according to any one of claims 1 to 14.

16. A computer-readable medium on which the computer program according to claim 15 is stored.

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