Method, control device and computer program for determining the rich gas content in the exhaust gas of an internal combustion engine, as well as an exhaust gas tract, internal combustion engine, vehicle and computer-readable medium

Abstract

The invention relates to a method, a control device and a computer program for determining the rich gas content in the exhaust gas of an internal combustion engine, as well as an exhaust gas tract, an internal combustion engine, a vehicle and a computer-readable medium. An oxidation catalyst device (110), a first exhaust gas sensor (120) arranged upstream thereof, and a second exhaust gas sensor (130) arranged downstream thereof are also provided. The method according to the invention comprises receiving a first exhaust gas signal from the first exhaust gas sensor (130), receiving a second exhaust gas signal from the second exhaust gas sensor (130), determining a difference at least partially on the basis of the received first exhaust gas signal and the received second exhaust gas signal, determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110) at least partially on the basis of the determined difference, and transmitting a rich gas signal which is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110).

Description

[0001] 202400806

[0002] 1

[0003] Description

[0004] Method, control device and computer program for determining the fatty gas content in the exhaust gas of an internal combustion engine, as well as exhaust system, internal combustion engine, vehicle and computer-readable medium

[0005] The present invention relates to a method, a control device and a computer program for determining the fatty gas content, such as hydrogen content, in the exhaust gas of an internal combustion engine, such as a hydrogen internal combustion engine, a diesel internal combustion engine or a gasoline internal combustion engine, as well as an exhaust system, an internal combustion engine, a vehicle and a computer-readable medium.

[0006] In internal combustion engines, such as diesel engines, catalysts, such as oxidation catalysts, particularly diesel oxidation catalysts (DOCs), are used for exhaust aftertreatment to reduce the emission of rich gas components, such as hydrocarbons (HC) and carbon monoxide (CO), by converting these substances to carbon dioxide (CO2) and water (H2O). This process occurs in an oxidation catalyst, especially when the catalyst reaches an operating temperature of approximately 250 °C. At this temperature, the so-called "light-off" temperature is reached.

[0007] In practice, however, it has been shown that the actual operating temperature or "light-off" temperature is not a fixed temperature threshold, but rather depends on certain operating and boundary conditions, such as the coating of the catalyst device, the exhaust gas mass flow, the aging state of the catalyst device, and / or the degree of catalyst poisoning. Consequently, even at catalyst device temperatures higher than the predetermined operating temperature, which is, for example, approximately 250 °C, incomplete conversion of the carbon compounds can still occur. On the other hand, the 202400806

[0008] 2

[0009] The catalyst device reaches its "light-off" temperature at a temperature lower than the predetermined operating temperature, so that further external heating of the catalyst device is no longer necessary.

[0010] DE 10 2021 203 282 relates to a method for operating an oxidation catalyst device arranged in the exhaust system of an internal combustion engine, which is designed to oxidize the carbon compounds present in the exhaust gas, and to an exhaust system. An exhaust gas sensor is also arranged downstream of the oxidation catalyst device, which is designed to detect the carbon content in the exhaust gas. The method according to the invention comprises determining the carbon content in the exhaust gas by means of the exhaust gas sensor and heating the oxidation catalyst device when the determined carbon content in the exhaust gas exceeds a predetermined carbon threshold value.

[0011] DE 43 41 632 A1 relates to a method and a device for testing and controlling motor vehicles using a known method for determining the air factor lambda from the oxygen partial pressure of the exhaust gas brought almost to total chemical equilibrium, given knowledge of the average fuel composition. In addition to the oxygen partial pressure of the exhaust gas brought almost to chemical equilibrium, the oxygen partial pressure in exhaust gas that has not been exposed to any means of achieving total gas equilibrium is measured, lambda is calculated from the two oxygen partial pressures, the difference between the lambda values ​​is determined, and this difference is used as a measure of the concentration of the sum of the hydrocarbon residues in the exhaust gas.

[0012] Further state of the art includes FR 3 139 600 A1 , DE 10 2020 209 159 B4, FR 2 950 386 B1 , US 2008 / 0 041 034 A1 and US 8 161 729 B2.

[0013] The present invention is essentially based on the objective of providing a method and a control device with which the rich gas content in the exhaust gas of the internal combustion engine can be controlled at an upstream position.

[0014] 3. The content of an oxidation catalyst device can be determined in a simple and reliable manner. Based on the determined rich gas content, the operating parameters of the internal combustion engine can then be adjusted for efficient and emission-reduced operation.

[0015] This problem is solved by a method according to claim 1, a control device according to claim 8, an exhaust system according to claim 10, an internal combustion engine according to claim 12, a vehicle according to claim 13, a computer program according to claim 14, and a computer-readable medium according to claim 15. Advantageous embodiments are specified in the dependent claims.

[0016] The present invention is essentially based on the idea of ​​a method for determining the fatty gas content, such as hydrogen content, in the exhaust gas of an internal combustion engine, particularly a hydrogen internal combustion engine, at a position upstream of an oxidation catalyst device. This method involves determining the difference between the oxygen content upstream and downstream of the oxidation catalyst device using exhaust gas sensors arranged in such a way as to be cross-sensitive to the fatty gas components, and then drawing conclusions about the fatty gas content, particularly hydrogen content, in the exhaust gas of the internal combustion engine, particularly a hydrogen internal combustion engine, based on this difference. The present invention takes advantage of the fact that there is a correlation between the determined difference across the oxidation catalyst device and the corresponding fatty gas content, particularly hydrogen content.In particular, the present invention makes use of the cross-sensitivity of the exhaust gas sensors to rich gases in such a way that a difference between the sensor signals of the exhaust gas sensors can be used to determine the rich gas content.

[0017] Consequently, according to a first aspect of the present invention, a method for determining the rich gas content in the exhaust gas of an internal combustion engine at a position upstream of an oxidation catalyst device is disclosed, which is used for 202400806

[0018] 4

[0019] The system is designed to oxidize the rich gas contained in the exhaust gas. Upstream of the oxidation catalyst device, a first exhaust gas sensor is arranged, which is configured to generate a first exhaust gas signal representative of the oxygen content in the exhaust gas that has diffused into the first exhaust gas sensor at the measuring position and originates from the exhaust gas upstream of the oxidation catalyst device. Downstream of the oxidation catalyst device, a second exhaust gas sensor is arranged, which is configured to generate a second exhaust gas signal representative of the oxygen content in the exhaust gas that has diffused into the second exhaust gas sensor at the measuring position and originates from the exhaust gas downstream of the oxidation catalyst device.The method according to the invention comprises receiving a first exhaust gas signal from the first exhaust gas sensor, receiving a second exhaust gas signal from the second exhaust gas sensor, determining a difference at least partially based on the received first exhaust gas signal and the received second exhaust gas signal, determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device at least partially based on the determined difference, and sending a rich gas signal that is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device.

[0020] Using the method according to the invention, the rich gas content upstream of the oxidation catalyst device in the exhaust gas of the internal combustion engine can therefore be determined in a simple and reliable manner and used for adjusting the operating parameters of the internal combustion engine. The present invention utilizes the cross-sensitivity of the exhaust gas sensor to the rich gas components present in the exhaust gas, such as hydrogen, by ensuring that the rich gas components present in the exhaust gas are at least partially oxidized as they diffuse into the exhaust gas sensor up to the measuring position within the sensor. In particular, chemical reactions, such as the oxidation of hydrogen, already occur within the exhaust gas along this diffusion path from the exhaust tract to the measuring position within the sensor.

[0021] 5

[0022] The hydrogen contained in the exhaust gas is detected instead. This influence of the change in exhaust gas composition, especially the oxygen content, when the exhaust gas diffuses into the exhaust gas sensor can be described as the cross-sensitivity of the exhaust gas sensor to the rich gas components contained in the exhaust gas.

[0023] Thus, upstream of the oxidation catalyst device, where the first exhaust gas sensor is also located, the composition of the exhaust gas at the measuring position of the first exhaust gas sensor can differ from the composition of the exhaust gas in the exhaust tract upstream of the oxidation catalyst device. Before the minimum operating temperature or light-off temperature of the oxidation catalyst device is reached, this also applies to the exhaust gas downstream of the oxidation catalyst device, which diffuses into the second exhaust gas sensor and can change its composition during this diffusion due to the oxidation of the rich gas components contained in the exhaust gas. After reaching the minimum operating temperature or light-off temperature,However, at the light-off temperature of the oxidation catalyst device, the rich gas components are essentially completely oxidized, so that the composition of the exhaust gas at the measuring position of the second exhaust gas sensor is essentially the same as the composition of the exhaust gas in the exhaust tract downstream of the oxidation catalyst device.

[0024] The present invention thus takes advantage of the fact that the concentration of rich gas components upstream of the oxidation catalyst device can be determined by calculating the difference between the received first exhaust gas signal and the received second exhaust gas signal. This difference can be calculated using the oxygen concentrations determined from the respective exhaust gas signals or directly using the two respective exhaust gas signals themselves.

[0025] In a preferred embodiment, the method according to the invention further comprises receiving a temperature signal that is representative of the temperature of the oxidation catalyst device, and determining that the received 202400806

[0026] 6

[0027] The temperature signal indicates a temperature of the oxidation catalyst device that is higher than a predetermined temperature threshold. The determination of the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device, based at least partially on the determined difference, only occurs once it has been established that the received temperature signal indicates a temperature of the oxidation catalyst device that is higher than the predetermined temperature threshold.

[0028] It is particularly preferred if the predetermined temperature threshold indicates the minimum operating temperature or light-off temperature of the oxidation catalyst device. This means that the process according to the invention is preferably only carried out when the oxidation catalyst device has reached its operating temperature and is thus within its optimal operating range. Preferably, the predetermined temperature threshold is approximately 250 °C.

[0029] According to a further advantageous embodiment of the method according to the invention, determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device involves at least partially assigning the determined difference to a corresponding rich gas content value. It is particularly preferred that the assignment of the determined difference to the corresponding rich gas content value is carried out using an assignment table and / or an assignment formula and / or an assignment diagram. Preferably, these assignment rules are determined from previously obtained empirical measurements with predetermined sample gases.

[0030] According to a further advantageous embodiment, the method according to the invention further comprises determining that the measured difference exceeds a predetermined difference threshold and ascertaining that the oxidation catalyst device has reached its minimum operating temperature or light-off temperature when it has been determined that the measured difference exceeds a predetermined difference threshold. 202400806

[0031] 7

[0032] In this preferred embodiment, the present invention takes advantage of the fact that it can be assumed that the oxidation catalyst device maintains its minimum operating temperature.

[0033] The light-off temperature has been reached when the measured difference exceeds the predetermined threshold. Only then can it be stated that the conversion of oxygen or the oxidation of the rich gas components in the oxidation catalyst device is proceeding as desired, which is only possible once the minimum operating temperature or light-off temperature of the oxidation catalyst device has been reached. Thus, the measured difference then exceeds the predetermined threshold. It should be noted that the presence of a rich gas component, such as hydrogen, is a prerequisite for this. The presence of such a rich gas component can be simulated, for example, through model calculations using the operating parameters of the internal combustion engine, for instance, by deliberately inducing hydrogen slip through the internal combustion engine, preferably a hydrogen-powered engine.

[0034] According to a further aspect of the present invention, a control device is disclosed which is configured to perform the steps of a method according to the invention.

[0035] According to a preferred embodiment, the control device according to the invention comprises a first control device section for performing the step of receiving a first exhaust gas signal from the first exhaust gas sensor, a second control device section for performing the step of receiving a second exhaust gas signal from the second exhaust gas sensor, a third control device section for performing the step of determining a difference at least partially based on the received first exhaust gas signal and the received second exhaust gas signal, and a fourth control device section for performing the step of determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device at least partially based on the determined 202400806

[0036] 8

[0037] difference and a fifth control device section for performing the step of sending a rich gas signal that is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device.

[0038] According to a further aspect of the present invention, an exhaust system for an internal combustion engine is disclosed, comprising an oxidation catalyst device configured to oxidize the rich gas in the exhaust gas, a first exhaust gas sensor arranged upstream of the oxidation catalyst device, configured to generate a first exhaust gas signal representative of the oxygen content in the exhaust gas diffused into the first exhaust gas sensor at the measuring position, which originates from the exhaust gas upstream of the oxidation catalyst device, a second exhaust gas sensor arranged downstream of the oxidation catalyst device, configured to generate a second exhaust gas signal representative of the oxygen content in the exhaust gas diffused into the second exhaust gas sensor at the measuring position, which originates from the exhaust gas downstream of the oxidation catalyst device, and a control device according to the invention.

[0039] In a preferred embodiment of the exhaust system according to the invention, the first exhaust gas sensor and / or the second exhaust gas sensor is an oxygen sensor, a nitrogen oxide sensor, a binary lambda probe, a linear lambda probe or any other sensor that is sensitive to oxygen and cross-sensitive to rich gas components.

[0040] According to a further aspect of the present invention, an internal combustion engine with an exhaust system according to the invention is disclosed.

[0041] According to a further aspect, a vehicle with an internal combustion engine according to the invention is disclosed. 202400806

[0042] 9

[0043] According to a further aspect of the present invention, a computer program is disclosed comprising instructions which, when executed by a computing unit, cause the computing unit to execute a method according to the invention for determining the fat gas content in the exhaust gas of an internal combustion engine.

[0044] According to a further aspect of the present invention, a computer-readable medium is disclosed on which the computer program according to the invention is stored.

[0045] Further features and functions of the present invention will become apparent to the person skilled in the art by carrying out the present teaching and by looking at the accompanying drawings, in which:

[0046] Fig. 1 shows a schematic view of an exhaust system of an internal combustion engine according to the invention,

[0047] Fig. 2 shows an exemplary flowchart of a method according to the invention for determining the rich gas content in the exhaust gas flowing through the exhaust tract of Fig. 1 upstream of an oxidation catalyst device arranged therein, and

[0048] Fig. 3 shows a diagram illustrating the relationship between a determined oxygen difference between the exhaust gas signals downstream of the catalyst device and the rich gas content.

[0049] Within the scope of this disclosure, the term "fat gas" describes any gas components or molecules present in the exhaust gas of the internal combustion engine that can react with or bind the oxygen present in the exhaust gas. These can include, for example, carbon compounds such as carbon monoxide, hydrocarbon compounds such as methane, ethane, and propane, hydrogen compounds, pure hydrogen, and other gas components. Consequently, within the scope of this disclosure 202400806

[0050] 10

[0051] Disclosure: The term "grease gas content" refers to the content or concentration of the respective gas component in the exhaust gas of the internal combustion engine.

[0052] Within the scope of this disclosure, the term "cross-sensitivity" describes a property of an exhaust gas sensor such that the generated exhaust gas signal can be at least partially distorted by any rich gas components present. This means that the exhaust gas signal from the sensor is only representative of the composition of the exhaust gas at the measurement point within the sensor, but not necessarily of the composition of the exhaust gas in the exhaust system of the internal combustion engine before it enters the sensor. This is primarily due to the fact that chemical reactions, such as the oxidation of hydrogen present in the exhaust gas, can occur along the diffusion path of the exhaust gas from the exhaust system to the measurement point within the sensor, so that the exhaust gas composition at the measurement point can differ from that in the exhaust system.

[0053] Fig. 1 shows a schematic view of an exhaust system 100 according to the invention for an internal combustion engine (not explicitly shown), such as a hydrogen engine, a diesel engine, or a gasoline engine. In particular, the exhaust gas from the internal combustion engine enters the exhaust system 100 via arrow 102. The exhaust system 100 comprises an oxidation catalyst device 110 and an optional catalyst device 140 with selective catalytic reduction arranged downstream of it. For example, the optional catalyst device 140 can be a purely selective catalytic reduction device (“selective catalytic reduction” SCR) or a particulate filter with a selective catalytic reduction coating.

[0054] The oxidation catalyst device can be an oxidation catalyst in which the fatty gas components, such as carbon compounds, are oxidized. In particular, in the oxidation catalyst device 110, the fatty gas components present in the exhaust gas, such as carbon compounds, are oxidized.

[0055] 11

[0056] Hydrocarbon compounds, carbon monoxides and pure hydrogen, converted or transformed, for example into carbon dioxide and water.

[0057] The exhaust system 100 further comprises a first exhaust gas sensor 120 arranged upstream of the oxidation catalyst device 110 and a second exhaust gas sensor 130 arranged downstream of the oxidation catalyst device 110. Optionally, a further exhaust gas sensor 150 can be arranged downstream of the optional catalyst device 140. The first exhaust gas sensor 120 is configured to generate a first exhaust gas signal that is representative of the oxygen content in the exhaust gas that has diffused into the first exhaust gas sensor 120 at the measuring position within the first exhaust gas sensor 120 and that originates from the exhaust gas upstream of the oxidation catalyst device 110. The second exhaust gas sensor 130 is configured to generate a second exhaust gas signal that is representative of the oxygen content in the exhaust gas that has diffused into the second exhaust gas sensor 130 at the measuring position of the second exhaust gas sensor 130 and that originates from the exhaust gas downstream of the oxidation catalyst device 110.In particular, the exhaust gas sensors 120 and 130 could be nitrogen oxide sensors, which, in addition to their primary function of measuring the nitrogen oxide content in the exhaust gas, can also generate the respective exhaust gas signal that is cross-sensitive to the rich gas components. Furthermore, the two exhaust gas sensors 120 and 130 could be any sensor capable of detecting the oxygen content in the exhaust gas and generating and transmitting a corresponding exhaust gas signal, such as linear or binary lambda sensors.

[0058] In order for selective catalytic reduction to take place in the catalyst device 140, a reducing agent injection device 142 can be located upstream of the catalyst device 140 and downstream of the exhaust gas sensor 130, via which a reducing agent, such as an aqueous urea solution, can be injected into the exhaust gas.

[0059] Optionally, an additional exhaust gas sensor 170, such as a nitrogen oxide sensor, can be provided downstream of the catalyst device 140. 202400806

[0060] 12

[0061] The exhaust system 100 also has a control device 160, which is connected via suitable connecting lines to the exhaust gas sensors 120, 130, 170 and the reducing agent injection device 142 and is designed to control the exhaust system 100.

[0062] The control device 160 can have several control device sections, such as a first control device section 161, a second control device section 162, a third control device section 163, a fourth control device section 164 and a fifth control device section 165, which will be discussed in more detail below with reference to Fig. 2.

[0063] The control device 160 can include a processor or arithmetic unit and memory. Alternatively, the control device 160 can be the processor or arithmetic unit connected to the memory. The processor can be a central processing unit (CPU). The processor can also be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or the like. The general-purpose processor can be a microprocessor, or the processor can be any conventional processor or the like.

[0064] The memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), or portable read-only memory (e.g., CD-ROM). The memory is configured to store associated program instructions and data. 202400806

[0065] 13

[0066] With additional reference to Fig. 2, which shows an exemplary flowchart of a method according to the invention for determining the rich gas content in the exhaust gas of the exhaust tract 100 of Fig. 1, a method according to the invention is explained below.

[0067] The process of Fig. 2 starts at step 200 and then proceeds to step 210, where the control device 160, in particular the first control device section 161, receives a first exhaust gas signal from the first exhaust gas sensor 120. The first exhaust gas signal can, for example, indicate the oxygen content in the exhaust gas at the measuring position of the first exhaust gas sensor 120 and is cross-sensitive to the rich gas components present in the exhaust gas. Alternatively, the first exhaust gas signal can be a linear or binary lambda signal, which in each case indicates the lambda value of the exhaust gas at the measuring position of the first exhaust gas sensor 120. The lambda signal is therefore also representative (directly or indirectly) of the oxygen content in the exhaust gas at the measuring position of the first exhaust gas sensor 120.

[0068] In a subsequent step 220, which preferably follows the first step 210, the control device 160, in particular the second control device section 162, receives a second exhaust gas signal from the second exhaust gas sensor 130. The time difference between the reception of the first and second exhaust gas signals can be selected such that the substantially same exhaust gas, which has meanwhile passed through the oxidation catalyst device, is measured at the position of the first exhaust gas sensor 120 and at the position of the second exhaust gas sensor 130. For example, it may be preferred to take the flow velocity or the exhaust gas mass flow rate into account. The second exhaust gas signal can, for example, indicate the oxygen content in the exhaust gas at the measuring position of the second exhaust gas sensor 130 and is cross-sensitive to the rich gas components present in the exhaust gas.Alternatively, the second exhaust gas signal can be a linear or binary lambda signal, which in each case indicates the lambda value of the exhaust gas at the measuring position of the second exhaust gas sensor 130. The lambda signal is therefore also representative (directly or indirectly) of 202400806.

[0069] 14 the oxygen content in the exhaust gas at the measuring position of the second exhaust gas sensor 130.

[0070] In a subsequent step 230, a difference is determined using the control device 160, in particular using the third control device section 163. Specifically, the difference is determined at least partially based on the first exhaust gas signal received in step 210 and the second exhaust gas signal received in step 220. The determined difference can be, for example, an oxygen content difference or a lambda difference.

[0071] In a subsequent step 240, the fat gas content in the exhaust gas of the internal combustion engine is determined using the control device 160, in particular using the fourth control device section 164. The determination of the fat gas content is based, at least in part, on the difference determined in step 230. The determined difference can be assigned to a corresponding fat gas content, for example, using an assignment table and / or an assignment formula and / or an assignment diagram. These assignment rules are determined, in particular, by means of previously performed empirical measurements with various predetermined sample gases.

[0072] In a subsequent step 250, a rich gas signal is sent, which is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device 110, before the procedure ends at step 260.

[0073] Although not shown, a query may precede step 210 to check whether the oxidation catalyst device 110 is operating within its optimal temperature range. In particular, it is preferred that the method according to the invention, especially steps 210 to 250, is only carried out after it has been determined that the oxidation catalyst device 110 is operating within its optimal temperature range.

[0074] 15

[0075] operating range. This can be done, for example, by means of a temperature sensor provided in the oxidation catalyst device 110, which is designed to generate a temperature signal that is representative of the temperature of the oxidation catalyst device 110. Alternatively, the temperature of the oxidation catalyst device 110 can be estimated or determined using a temperature model.

[0076] Steps 210 to 250 are only carried out once the measured temperature of the oxidation catalyst device 110 is above the minimum operating temperature or predetermined light-off temperature. This is because only when the oxidation catalyst device 110 has reached its minimum operating temperature or predetermined light-off temperature can it be assumed that the exhaust gas downstream of it is essentially free of rich gas components, and thus the exhaust gas measured by the second exhaust gas sensor 130 is essentially the same as the exhaust gas in the exhaust tract downstream of the oxidation catalyst device 110. Accordingly, the cross-sensitivity of the second exhaust gas sensor 130 to rich gas components then has essentially no further effect.

[0077] Instead of using a temperature sensor, the determination that the oxidation catalyst device 110 is operating within its optimal temperature range, for example, above approximately 250 °C, can be made using the difference determined in step 230. In particular, step 230 can be followed by a query to check whether the determined difference exceeds a predetermined threshold. If the difference is found to be below this threshold, it can be determined that the oxidation of the rich gas in the oxidation catalyst device 110 is not yet sufficiently advanced and, consequently, its operating temperature has not yet been reached.However, if the difference determined in step 230 exceeds the predetermined difference threshold, it can be assumed that a sufficiently high oxidation of the rich gas takes place within the oxidation catalyst device, and consequently the 202400806.

[0078] 16

[0079] Oxidation catalyst device 110 is in its temperature-optimal operating range.

[0080] The monitoring of the temperature and / or the determined difference can be carried out continuously, and thus the heating or warming of the oxidation catalyst device 110 can be controlled as required.

[0081] In a further preferred embodiment of the method according to the invention, the condition of the internal combustion engine can also be determined during predetermined operating modes of the engine, such as the overrun fuel cut-off phase, by evaluating the rich gas content. If the internal combustion engine is, for example, a hydrogen engine and the hydrogen content in the exhaust gas of the engine is determined by means of the method according to the invention during such an overrun fuel cut-off phase, this determined hydrogen content can provide an indication of the crankcase ventilation of the hydrogen engine.If the measured hydrogen content exceeds a predetermined hydrogen content threshold, such as 4%, it can be concluded that there is an excessive accumulation of hydrogen in the crankcase of the hydrogen combustion engine, so that immediate venting of the crankcase may be necessary to reduce the risk of explosion.

[0082] As already mentioned, the rich gas can consist of pure hydrogen, hydrocarbons, carbon compounds such as carbon monoxide, and other compounds and molecules that are present in the exhaust gas alongside oxygen and can react with it.

[0083] Figure 3 shows a diagram illustrating the relationship between a determined oxygen difference AO2, calculated based on the first exhaust gas signal from the first exhaust gas sensor 120 and the second exhaust gas signal from the second exhaust gas sensor 130, and the corresponding rich gas content c_rich gas. This is shown in Figure 202400806.

[0084] 17

[0085] It should be noted again that Fig. 3 uses the oxygen difference AO2 as an example. However, it is also in accordance with the invention that the lambda difference, for example the binary lambda difference, or any other difference that is representative of the oxygen content in the exhaust gas, can be used instead.

[0086] The dash-dot line 302 in Fig. 3 shows the course of the rich gas content c_rich gas versus the oxygen difference AO2 across the catalyst device 110. The oxygen difference AO2 is formed from the first exhaust gas signal of the first exhaust gas sensor 120 and the second exhaust gas signal of the second exhaust gas sensor 130.

[0087] As can be seen in Fig. 3, the rich gas content c_rich gas increases with increasing oxygen difference AO2. This is because oxygen is converted in the catalyst device 110, which is preferably an oxidation catalyst device; that is, the oxygen present in the exhaust gas reacts with the rich gas present in the exhaust gas. Consequently, the first exhaust gas signal from the first exhaust gas sensor 120 indicates a higher oxygen content than the second exhaust gas signal from the second exhaust gas sensor 130, since the greater the rich gas content c_rich gas in the exhaust gas, the more oxygen is converted in the catalyst device 110. The dash-dot line 302 can therefore also indicate the conversion capacity of the catalyst device 110.

[0088] As described above, chemical reactions, in particular oxidations of the rich gases present in the exhaust gas, such as hydrogen, take place on the catalytic surfaces of the first exhaust gas sensor 120. Thus, as the exhaust gas diffuses into the cross-sensitive exhaust gas sensor 120, 130 up to the measuring position, oxygen is already reacted. This leads to the exhaust gas composition, especially the oxygen content and / or rich gas content, differing at the measuring position within the first exhaust gas sensor 120 compared to the exhaust gas tract upstream of the catalyst device 110. Consequently, the first exhaust gas signal of the first exhaust gas sensor 120 can be affected by the rich gases present in the exhaust gas and by the 202400806

[0089] The cross-sensitivity of the first exhaust gas sensor 120, as described in section 18, may be distorted, indicating a different, preferably lower, oxygen content in the exhaust gas than is actually present. It is apparent to a person skilled in the art that the first exhaust gas signal from the first exhaust gas sensor 120 can also indicate an oxygen content that is higher than is actually present in the exhaust gas.

[0090] The second exhaust gas sensor 130, which also exhibits cross-sensitivity to rich gases, is hardly or not at all subject to such distortion, since the rich gases have already been almost completely converted in the catalyst device 110 at the measuring position of the second exhaust gas sensor 130. Thus, the second exhaust gas sensor 130 essentially measures a rich gas-free exhaust gas, which is why the second exhaust gas signal of the second exhaust gas sensor 130 is representative of the oxygen content in the exhaust tract downstream of the catalyst device 110.

[0091] The present invention addresses precisely this point and corrects such a distorted exhaust gas signal upstream of the catalyst device 110. For this purpose, the dashed line 304 of Fig. 3, which was previously determined empirically using different sample gases with varying rich gas contents, can be provided and stored in the control system. The dashed line 304 shows the course of the rich gas content c_rich gas relative to the oxygen difference AO2 resulting from the first exhaust gas signal of the first exhaust gas sensor 120 and the second exhaust gas signal of the second exhaust gas sensor 130, which arises due to the cross-sensitivities of the exhaust gas sensors 120, 130, in particular the first exhaust gas sensor 120 located upstream of the catalyst device 110.

[0092] The course of the dashed line 304 in Fig. 3 is therefore in the negative range of the oxygen difference AO2, since the first exhaust gas signal of the first exhaust gas sensor 120 indicates a lower oxygen content than the second exhaust gas signal of the second exhaust gas sensor 130 due to the rich gases located in the exhaust gas upstream of the catalyst device 110 and due to its cross-sensitivity to rich gases, since at the measuring position of the second exhaust gas sensor 130 202400806

[0093] 19 Downstream of the catalyst device 110, the exhaust gas is essentially free of rich gas. Consequently, the maximum value of the oxygen difference AO2 between the first oxygen content indicated by the first exhaust signal and the second oxygen value indicated by the second exhaust signal is zero. It is also possible that the minimum value of the oxygen difference AO2 is zero, particularly in situations where the oxygen difference AO2 is essentially positive.

[0094] The dashed line 304 in Fig. 3 thus shows the dependence of the cross-sensitivity of the exhaust gas sensors 120, 130 on the rich gases present in the exhaust gas and was determined empirically beforehand using various sample gases. Therefore, when determining the oxygen difference AO2 between the first oxygen content indicated by the first exhaust gas signal and the second oxygen value indicated by the second exhaust gas signal, the corresponding rich gas content can be determined.

[0095] The solid line 306 in Fig. 3 describes a combination of lines 302 and 304, i.e., it takes into account both the conversion rate of the catalyst device 110 and the distortion due to the cross-sensitivities of the exhaust gas sensors 120, 130 to rich gases. Consequently, the solid line 306 describes the most accurate relationship between the determined oxygen difference AO2 and the corresponding rich gas content c_rich gas.

[0096] Preferably, the internal combustion engine is a hydrogen internal combustion engine in which the influence of the hydrogen conversion rate of the catalyst device 110 is negligibly small compared to the distortion due to the cross-sensitivity of the exhaust gas sensors 120, 130 to hydrogen. This is particularly important for the dashed line 304, since it can be assumed here that the hydrogen conversion in the catalyst device 110 can be neglected. 202400806

[0097] 20

[0098] According to the invention, it is therefore important that the exhaust gas sensors 120, 130 are cross-sensitive to rich gases, such as hydrogen, and that the dashed line 304 of Fig. 3 is empirically determined and provided beforehand with different sample gases with different rich gas contents.

[0099] The conversion effect of the catalyst device 110 (see line 302 of Fig. 2) therefore represents a disturbance variable for the effect of the cross-sensitivity of the exhaust gas sensors 120, 130, which, however, can be taken into account to improve the measurement accuracy.

Claims

202400806 21 Patent claims 1. A method for determining the rich gas content in the exhaust gas of an internal combustion engine at a position upstream of an oxidation catalyst device (110) configured to oxidize the rich gas present in the exhaust gas, wherein upstream of the oxidation catalyst device (110) a first exhaust gas sensor (120) is arranged, configured to generate a first exhaust gas signal representative of the oxygen content in the exhaust gas diffused into the first exhaust gas sensor (120) at the measuring position, which originates from the exhaust gas upstream of the oxidation catalyst device (110), and downstream of the oxidation catalyst device (110) a second exhaust gas sensor (130) is arranged, configured to generate a second exhaust gas signal representative of the oxygen content in the exhaust gas diffused into the second exhaust gas sensor (130) at the measuring position, which originates from the exhaust gas downstream of the oxidation catalyst device (110), wherein the method comprises: Receiving an initial exhaust signal from the first exhaust sensor (120), Receiving a second exhaust signal from the second exhaust sensor (130), Determining a difference at least partially based on the received first exhaust gas signal and the received second exhaust gas signal, determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110) at least partially based on the determined difference, and Sending a rich gas signal that is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110).

2. Method according to claim 1, further comprising: Receiving a temperature signal that is representative of the temperature of the oxidation catalyst device (110), and 202400806 22 Determine that the received temperature signal indicates a temperature of the oxidation catalyst device (110) that is greater than a predetermined temperature threshold, wherein the determination of the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110) is carried out at least partially based on the determined difference only after it has been determined that the received temperature signal indicates a temperature of the oxidation catalyst device (110) that is greater than the predetermined temperature threshold.

3. Method according to claim 2, wherein the predetermined temperature threshold indicates the minimum operating temperature or light-off temperature of the oxidation catalyst device (110).

4. Method according to one of claims 2 and 3, wherein the predetermined temperature threshold is approximately 250 °C.

5. Method according to one of the preceding claims, wherein the determination of the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110) at least partially comprises an assignment of the determined difference to a corresponding rich gas content value.

6. Method according to claim 5, wherein the determined difference is assigned to the corresponding fat gas content value by means of an assignment table and / or an assignment formula and / or an assignment diagram.

7. A method according to any of the preceding claims, further comprising: determining that the determined difference represents a predetermined The difference threshold is exceeded, and Determine that the oxidation catalyst device (110) has reached its minimum operating temperature or light-off temperature when it has been determined that the measured difference exceeds a predetermined difference threshold. 202400806 23 8. Control device (160) configured to perform the steps of the method according to any of the preceding claims.

9. Control device (160) according to claim 8, comprising: a first control device section (161) for performing the step of receiving a first exhaust gas signal from the first exhaust gas sensor (120), a second control device section (162) for performing the step of receiving a second exhaust gas signal from the second exhaust gas sensor (130), a third control device section (163) for performing the step of determining a difference at least partially based on the received first exhaust gas signal and the received second exhaust gas signal, a fourth control device section (164) for performing the step of determining the rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110) at least partially based on the determined difference, and a fifth control device section (165) for performing the step of sending a rich gas signal.which is representative of the determined rich gas content in the exhaust gas of the internal combustion engine upstream of the oxidation catalyst device (110).

10. Exhaust system (100) for an internal combustion engine, comprising: an oxidation catalyst device (110) configured to oxidize the rich gas present in the exhaust gas, a first exhaust gas sensor (120) arranged upstream of the oxidation catalyst device (110) configured to generate a first exhaust gas signal representative of the oxygen content in the exhaust gas diffused into the first exhaust gas sensor (120) at the measuring position, which originates from the exhaust gas upstream of the oxidation catalyst device (110), 202400806 24 a second exhaust gas sensor (130) arranged downstream of the oxidation catalyst device (110), which is configured to generate a second exhaust gas signal that is representative of the oxygen content in the exhaust gas diffused into the second exhaust gas sensor (130) at the measuring position, which originates from the exhaust gas downstream of the oxidation catalyst device (110), and a control device (160) according to one of claims 8 and 9.

11. Exhaust system (100) according to claim 10, wherein the first exhaust gas sensor (120) and / or the second exhaust gas sensor (130) is an oxygen sensor, a nitrogen oxide sensor, a linear lambda probe, a binary lambda probe or any other sensor that is sensitive to oxygen and cross-sensitive to rich gas components.

12. Internal combustion engine with an exhaust system (100) according to one of claims 10 and 11.

13. Vehicle with an internal combustion engine according to claim 12.

14. Computer program comprising instructions which, when executed by a computing unit, cause the computing unit to execute a method according to any one of claims 1 to 7.

15. Computer-readable medium on which the computer program according to claim 14 is stored.

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