Method for monitoring the ventilation of a crankcase of a hydrogen internal combustion engine and hydrogen internal combustion engine

Abstract

The present invention relates to a method for monitoring the ventilation of a crankcase (120) of a hydrogen internal combustion engine (100) and to a hydrogen internal combustion engine (100) which has combustion chambers (110) and a gas sensor (140) arranged in the exhaust tract (130) of the hydrogen internal combustion engine (100), which gas sensor is designed to generate a gas signal which is representative of the hydrogen content or oxygen content in the exhaust gas of the hydrogen internal combustion engine (100).The method according to the invention comprises determining a predetermined operating mode of the hydrogen internal combustion engine (100) during which substantially no combustion of an air-hydrogen mixture takes place within the combustion chambers (110), receiving a gas signal from the gas sensor (140) during the predetermined operating mode of the hydrogen internal combustion engine (100), determining the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) based at least partially on the received gas signal, and determining a functional ventilation of the crankcase (120) if the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content threshold.

Description

[0001] The present invention relates to a method for monitoring the ventilation of a crankcase of a hydrogen internal combustion engine and to a hydrogen internal combustion engine, in particular to a hydrogen internal combustion engine with crankcase ventilation.

[0002] In (piston) internal combustion engines with a closed crankcase, deviations from atmospheric pressure occur not only in the working chambers but also below the pistons. These are caused, on the one hand, by the volume changes caused by the rotating pistons and, on the other hand, by the gases accumulating in the crankcase from the working process.

[0003] In combustion engines, so-called blowby gases always occur in the crankcase. Since the crankcase is a closed space, the pressure would constantly increase without ventilation. To prevent this, the blowby gases, which contain combustion products and unburned hydrogen, can be specifically removed from the crankcase. The ideal relative crankcase pressure is in the slightly negative range of around -2 mbar, since under these conditions the engine does not tend to "sweat out" lubricating oil. If the negative pressure is significantly greater (the value is engine-specific and depends on the design of the sealing systems), there is a risk that air contaminated with dirt particles and / or pure hydrogen will be sucked in via the shaft seals and gaskets on the crankcase. This would lead to increased wear on internal components.During venting, oil droplets generated by rotating components are inevitably carried out of the crankcase.

[0004] During operation of the hydrogen internal combustion engine, in particular during overrun fuel cut-off phases of the hydrogen internal combustion engine, high pressure in the intake manifold can cause the gases trapped in the crankcase (in particular pure hydrogen present there) to at least partially pass past the pistons into the combustion chambers and thus into the exhaust tract of the hydrogen internal combustion engine.

[0005] Furthermore, the ventilation line can become blocked, torn off, or the connection to the intake tract can be missing. This restricts crankcase ventilation, allowing pollutants and pure hydrogen to escape unhindered from the crankcase into the environment. Therefore, the hydrogen content in the exhaust gas of the hydrogen internal combustion engine and / or in the crankcase, as well as the proper functioning of the crankcase ventilation, should be monitored. If the crankcase ventilation is not functioning properly, pure hydrogen will accumulate in the crankcase and / or be released unhindered into the environment in the event of a leak. If temperature-dependent explosion limits regarding the hydrogen content in the exhaust gas and / or in the crankcase of the hydrogen internal combustion engine are exceeded, there is also a risk of ignition of the air-hydrogen mixture.

[0006] DE 10 2021 213 901 B3 discloses a method for monitoring the ventilation of a crankcase of a fossil internal combustion engine. The method known therefrom comprises determining a predetermined operating mode of the internal combustion engine during which substantially no combustion of an air-fuel mixture takes place within the combustion chambers, determining a nitrogen oxide content in the exhaust gas of the internal combustion engine during the predetermined operating mode of the internal combustion engine by means of an exhaust gas sensor and determining a functional ventilation of the crankcase if the nitrogen oxide value determined during the predetermined operating mode of the internal combustion engine exceeds a predetermined nitrogen oxide threshold value.

[0007] Further known methods and devices are known from DE 10 2022 115 404 A1, DE 10 2020 209 159 A1, DE 10 2019 212 457 A1, DE 10 2013 224 030 A1, DE 197 57 345 B4 and DE 10 2022 209 670 A1.

[0008] The present invention is essentially based on the object of determining and checking the proper functionality of a crankcase ventilation system of a hydrogen internal combustion engine in a simple and cost-effective manner.

[0009] This object is achieved by a method according to independent claim 1 and a hydrogen internal combustion engine according to independent claim 12. Advantageous embodiments are specified in the subclaims.

[0010] The present invention is essentially based on the idea that, during predetermined operating modes during which no combustion of an air-hydrogen mixture occurs in the combustion chambers of the internal combustion engine, the crankcase ventilation is monitored by means of a gas sensor provided in the exhaust tract of the internal combustion engine. In particular, during the aforementioned predetermined operating modes, the exhaust gases trapped in the crankcase re-enter the combustion chambers and thus the exhaust tract via the ventilation line and / or as so-called blowby exhaust gases, and can thus be detected (directly or indirectly) by the gas signal arranged in the exhaust tract.If the gas sensor, which is already arranged and present in the exhaust tract, generates a gas signal during the predetermined operating modes of the hydrogen internal combustion engine that is representative of a hydrogen content that lies above a predetermined hydrogen content threshold, it can be concluded that the crankcase ventilation is functioning properly and correctly, since the ventilation path from the crankcase into the combustion chambers and thus into the exhaust tract is free and unblocked. However, if the gas signal from the gas sensor indicates a hydrogen content that lies below the predetermined hydrogen content threshold during these predetermined operating modes of the hydrogen internal combustion engine, it can be concluded that the crankcase ventilation is not functioning properly. In particular, it can then be determined that the ventilation path from the crankcase into the exhaust tract is at least partially blocked or clogged.

[0011] Accordingly, according to a first aspect of the present invention, a method for monitoring the ventilation of a crankcase of a hydrogen internal combustion engine is disclosed, which has combustion chambers and an oxygen sensor arranged in an exhaust tract of the hydrogen internal combustion engine, which oxygen sensor is configured to generate an oxygen signal representative of the oxygen content in the exhaust gas of the hydrogen internal combustion engine. The method according to the invention comprises determining a predetermined operating mode of the hydrogen internal combustion engine during which substantially no combustion of an air-hydrogen mixture takes place within the combustion chambers, determining the actual oxygen content in the exhaust gas of the hydrogen internal combustion engine based on the determined predetermined operating mode of the hydrogen internal combustion engine,receiving an oxygen signal from the oxygen sensor during the predetermined operating mode of the hydrogen internal combustion engine, determining the oxygen content in the exhaust gas of the hydrogen internal combustion engine based on the oxygen signal received from the oxygen sensor, forming an oxygen content difference between the determined actual oxygen content and the oxygen content determined based on the oxygen signal received from the oxygen sensor, determining the hydrogen content in the exhaust gas of the hydrogen internal combustion engine based at least partially on the determined oxygen content difference, and determining a functional ventilation of the crankcase if the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine exceeds a predetermined hydrogen content threshold.

[0012] By determining the hydrogen content in the exhaust gas of the hydrogen internal combustion engine during the predetermined operating mode, it is possible to check whether the crankcase ventilation into the exhaust tract of the hydrogen internal combustion engine is free and unblocked. If this were to be blocked, the determined hydrogen content would fall below the predetermined hydrogen content threshold, since no hydrogen accumulated in the crankcase would enter the exhaust tract during the predetermined operating mode.

[0013] This takes advantage of the fact that the hydrogen present in the exhaust gas acts as a rich gas. This means that the hydrogen reacts with the oxygen in the exhaust gas at the electrodes and catalytic surfaces of the oxygen sensor to form water. Consequently, the oxygen content indicated by the oxygen sensor is lower than the actual oxygen content because the hydrogen present in the exhaust gas reacts with a corresponding proportion of oxygen in the exhaust gas. The difference between the actual oxygen content and the oxygen content indicated by the oxygen sensor can be indicative of the hydrogen content in the exhaust gas because there is a correlation between the change in the oxygen signal and the hydrogen concentration, from which the hydrogen content in the exhaust gas can subsequently be determined.However, since the actual oxygen content is known in the predetermined operating modes, for example approximately 20.9% in air, the hydrogen content in the exhaust gas can be determined according to the invention based on the oxygen signal of the oxygen sensor.

[0014] In an alternative embodiment, it may be preferable for the hydrogen content to be determined only when an air mass integral in the exhaust tract exceeds a predetermined air mass integral threshold value. In particular, the time until the gas sensor can measure the exhaust gases originating from the crankcase depends on the mass flow rate and the volume of the exhaust tract. Consequently, in such an alternative embodiment, it is advantageous to determine the hydrogen content only when the air mass integral in the exhaust tract exceeds the predetermined air mass integral threshold value. Furthermore, the gas sensor requires a certain amount of time to settle to the respective measured value.

[0015] In an advantageous embodiment, the method according to the invention further comprises determining a malfunctioning crankcase ventilation system if the hydrogen content in the exhaust gas of the hydrogen internal combustion engine, determined during the predetermined operating mode of the hydrogen internal combustion engine, falls below the predetermined hydrogen content threshold. It may be preferred if the method according to the invention, in such an advantageous embodiment, additionally comprises issuing a warning to the operator of the hydrogen internal combustion engine if a malfunctioning crankcase ventilation system has been determined.

[0016] Preferably, the predetermined hydrogen content threshold is between about 0.3% and about 0.6%, and more preferably about 0.5%.

[0017] In a further advantageous embodiment, the method according to the invention further comprises determining an exhaust gas mass flow through the exhaust tract of the hydrogen internal combustion engine and determining the hydrogen content in the crankcase of the hydrogen internal combustion engine, at least partially based on the received oxygen signal from the oxygen sensor and at least partially based on the determined exhaust gas mass flow through the exhaust tract of the hydrogen internal combustion engine. In particular, the hydrogen content in the crankcase can be determined by correlating the determined hydrogen content in the exhaust gas with the determined exhaust gas mass flow. The correlation can be provided, for example, in the form of a lookup table and / or a mathematical mapping.

[0018] Preferably, according to such a preferred embodiment, the method according to the invention further comprises determining that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds a predetermined hydrogen content threshold value, and at least partially venting the crankcase if it has been determined that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds the predetermined hydrogen content threshold value.

[0019] Particularly preferably, the method according to the invention additionally comprises determining the temperature of the gas mixture in the crankcase. The predetermined hydrogen content threshold value can then be predetermined as a function of the determined temperature of the gas mixture in the crankcase.

[0020] In a further advantageous embodiment, the method according to the invention additionally comprises issuing an alarm to the operator of the hydrogen internal combustion engine if it has been determined that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds the predetermined hydrogen content threshold. The alarm informs the operator that there is an increased risk of explosion of the crankcase.

[0021] According to a further aspect of the present invention, a hydrogen internal combustion engine is disclosed which is designed to be operated with hydrogen as fuel.The hydrogen internal combustion engine according to the invention has at least one combustion chamber which is formed by a piston which reciprocally reciprocates within a cylinder, a crankcase in which the piston is at least partially arranged and which is at least partially fluidly connected to the combustion chamber via a gap between the piston and the cylinder, an exhaust tract which is fluidly connected to the at least one combustion chamber, an oxygen sensor arranged in the exhaust tract which is designed to generate an oxygen signal which is representative of the hydrogen content or oxygen content in the exhaust gas of the hydrogen internal combustion engine, and a control unit which is designed to carry out a method according to the invention for monitoring the ventilation of a crankcase of the hydrogen internal combustion engine.

[0022] Preferably, the hydrogen internal combustion engine according to the invention further comprises an intake pipe which is fluidly connected to the at least one combustion chamber and is designed to supply air to the at least one combustion chamber for the combustion of an air-hydrogen mixture, and a vent line which fluidly connects the crankcase to the intake pipe.

[0023] In a further preferred embodiment, the hydrogen internal combustion engine according to the invention also has a ventilation line which fluidically connects the crankcase to the intake pipe, and a ventilation pump arranged in the ventilation line which is designed to pump air from the intake pipe into the crankcase for flushing the crankcase with air.

[0024] Further features and objects of the invention will become apparent to those skilled in the art by practicing the present teachings and viewing the accompanying drawings in which: Fig. 1 shows a schematic view of a hydrogen internal combustion engine of a vehicle, and Fig. 2 an exemplary flow diagram of a method according to the invention for monitoring the ventilation of the crankcase of the hydrogen internal combustion engine of Fig. 1 shows.

[0025] In the context of this disclosure, the term "hydrogen internal combustion engine" describes an internal combustion engine that uses hydrogen as fuel. A hydrogen internal combustion engine converts chemical energy into mechanical work and heat. It is based on the oxyhydrogen reaction (combustion of hydrogen) in a reciprocating piston or rotary piston internal combustion engine. Reciprocating piston engines that operate according to the Otto principle (= spark ignition) are usually used. However, according to the invention, this also includes hydrogen internal combustion engines that operate according to the diesel principle (= compression ignition).

[0026] The Fig. Figure 1 shows a schematic view of a hydrogen internal combustion engine 100 of a vehicle. The hydrogen internal combustion engine 100 has an intake pipe (or air intake line) 102 and combustion chambers 110 connected thereto (in the Fig. 1 (only one of the four combustion chambers 110 is provided with a reference numeral). Intake air can enter the combustion chambers 110 via the intake pipe 102, where the intake air can be mixed with hydrogen as fuel and combusted in a known manner. The flow direction of the intake air is indicated by arrow 104.

[0027] The combustion chambers 110 are formed, in particular, by cylinders 112 and pistons 114 reciprocating therein, whereby the volume of the combustion chambers 110 varies over time. The pistons 114 are at least partially arranged in a crankcase 120 and mechanically coupled to a crankshaft 122 arranged therein, which is known from the prior art.

[0028] The combustion chambers 110 are fluidly connected to an exhaust tract 130, through which the exhaust gases generated by the combustion of the air-hydrogen mixture in the combustion chambers 110 can be discharged into the environment. The exhaust tract 130 describes only the section of the hydrogen internal combustion engine 100 that is designed exclusively for discharging the exhaust gases.

[0029] Arranged in the exhaust tract 130 is a gas sensor 140, which is designed to generate a gas signal representative of the oxygen content in the exhaust gas at the position downstream of the combustion chambers 110. In an embodiment not according to the invention, the gas sensor 140 can also be a hydrogen sensor based on the thermal conductivity measurement principle, which is designed to determine the hydrogen content. In an embodiment not according to the invention, the hydrogen sensor 140 can also be any other hydrogen sensor known in the prior art that is designed to determine the hydrogen content in a gas mixture.

[0030] According to the invention, the gas sensor 140 is an oxygen sensor designed to generate an oxygen signal representative of the oxygen content in the exhaust gas of the hydrogen internal combustion engine 100. The oxygen sensor 140 can be a binary lambda sensor, a linear lambda sensor, a nitrogen oxide sensor, or any other sensor whose signal can be evaluated to determine the oxygen content. The oxygen sensor 140 cannot directly detect the hydrogen content. Rather, the oxygen content measured by the oxygen sensor 140 is influenced by the hydrogen content prevailing in the exhaust gas, since the hydrogen present acts as a rich gas and reacts with the oxygen present in the exhaust gas to form water at the electrodes and catalytic surfaces of the oxygen sensor 140. Consequently, the oxygen content determined by the oxygen sensor 140 is lower than the oxygen content actually present in the exhaust gas.The difference between the actual oxygen content, which can be assumed to be known in the predetermined operating mode, and the oxygen content determined by the oxygen sensor 140 can then be correlated with the hydrogen content in the exhaust gas. To determine the oxygen content difference, it is necessary that the actual oxygen content in the exhaust gas is known during the predetermined operating mode. This is the case, for example, during overrun cut-off phases of the hydrogen internal combustion engine 100, since during these overrun cut-off phases no fuel is metered in, but rather only the intake air is forced through the combustion chambers 110 and the exhaust tract 130. Under these conditions, a hydrogen content of approximately 20.9% can be assumed, which corresponds to the oxygen content in the air. The determined oxygen content difference can be correlated with the hydrogen content.

[0031] Furthermore, a control unit 160 is provided, which is in communication connection with the gas sensor 140 and is designed to receive the gas signal generated by the gas sensor 140 and to at least partially control the operation of the hydrogen internal combustion engine 100.

[0032] During operation of the hydrogen internal combustion engine 100, deviations from atmospheric pressure occur not only in the combustion chambers 110, but also below the pistons 114. These are caused, on the one hand, by the volume changes caused by the rotating pistons 114 and, on the other hand, by the exhaust gases from the working process accumulating in the crankcase 120. In particular, exhaust gases from the combustion chambers 110 can enter the crankcase 120 through a gap between the cylinder 112 and the piston 114, which in the Fig. 1 is indicated by an arrow 106.

[0033] In order to prevent these so-called blow-by gases from being expelled unhindered into the atmosphere, a vent line 124 is provided, which fluidically connects the crankcase 120 to the intake manifold 102. A control valve 126 is provided in the vent line 124, with which an active venting of the crankcase 120 into the intake manifold 102 can be controlled. The control valve 126 is preferably a pressure control valve, which can automatically control or regulate the pressure within the crankcase 120. Additionally or alternatively, the pressure in the crankcase 120 can be controlled with the aid of a mechanical regulating valve (in the Fig. 1 not shown) in the intake manifold 102. In particular, the exhaust gases collected in the crankcase 120 can be fed to the combustion chambers 110 and thus also to the exhaust tract 130 for later working cycles, where they can then be released into the environment in a controlled manner.

[0034] The hydrogen internal combustion engine 100 has, in the Fig. 1, the exemplary embodiment also includes a ventilation line 128 that fluidically connects the crankcase 120 to the intake pipe 102. A ventilation pump 129 is provided in the ventilation line 128, with which active ventilation of the crankcase 120 from the intake pipe 102 can be controlled. The ventilation pump 129 is particularly designed to pump air from the intake pipe 102 into the crankcase 120 when it is determined that the hydrogen content within the crankcase 120 exceeds a predetermined hydrogen content threshold value and thus there is an increased risk of explosion. By blowing air into the crankcase 120, the hydrogen content therein can be reduced, thus also reducing the risk of explosion.

[0035] According to the Fig. In the embodiment shown in Figure 1, the blowby gases are introduced into the intake manifold 102 via the vent line 124. Due to the negative pressure in the intake manifold 102, a negative pressure is also created in the crankcase 120 in most operating states of the internal combustion engine 100.

[0036] With additional reference to the Fig. 2, an exemplary embodiment of a method according to the invention for monitoring the functionality of the crankcase ventilation of the hydrogen internal combustion engine 100 of the Fig. 1 described as an example.

[0037] The procedure of Fig. 2 starts at step 200 and then proceeds to step 210, where it is determined whether the hydrogen internal combustion engine 100 is in a predetermined operating mode during which no combustion of an air-hydrogen mixture takes place within the combustion chambers 110. For example, a predetermined operating mode may be in the form of an overrun fuel cut-off phase of the hydrogen internal combustion engine 100. The method remains at step 210 until a predetermined operating mode is determined.

[0038] If a predetermined operating mode of the hydrogen internal combustion engine 100 is determined in step 210, the method proceeds to step 220, where a gas signal is generated by the gas sensor 140, which is received by the control unit 160. In a subsequent step 230, the hydrogen content in the exhaust gas of the hydrogen internal combustion engine 100 is determined based on the received gas signal. In the case of a hydrogen sensor not according to the invention as the gas sensor 140, this can be done directly from the hydrogen signal. According to the invention, the hydrogen content is determined, as already described, indirectly from the oxygen signal in the case of an oxygen sensor as the gas sensor.

[0039] In a subsequent step 240, it is determined whether the hydrogen content determined in step 230 exceeds a predetermined hydrogen content, such as 0.5%, for example. Preferably, after determining the predetermined operating mode of the hydrogen internal combustion engine 100, a predetermined period of approximately 3 seconds, preferably approximately 1 second, can be waited before step 240 is performed. This ensures that, at the time the gas signal is generated, the exhaust gases generated due to the combustion that previously took place in the combustion chambers 110 have already flowed past the gas sensor 140. Consequently, the exhaust gas measured in step 220 should be the exhaust gas vented from the crankcase 120.

[0040] If it is determined in step 240 that the hydrogen content determined in step 230 exceeds the predetermined hydrogen content threshold, the method proceeds to step 250, where a properly functioning crankcase ventilation system is diagnosed. In particular, exceeding the predetermined hydrogen content threshold can be interpreted as meaning that the exhaust gases containing hydrogen trapped in the crankcase 120 are vented either via the vent line 124 or past the pistons 114 (i.e., along the arrow 108 in the Fig. 1) into the combustion chambers 110 and thus into the exhaust tract 130. Thus, these two venting paths are essentially unblocked and essentially free.

[0041] However, if it is determined in step 240 that the hydrogen content determined in step 230 does not exceed, i.e., falls below, the predetermined hydrogen threshold value, the method proceeds to step 260, where an improperly functioning or malfunctioning crankcase ventilation system is diagnosed. In particular, falling below the predetermined hydrogen threshold value can be interpreted to mean that the exhaust gases trapped in the crankcase 120 cannot be vented as desired via the ventilation line 124 or past the pistons 114 (i.e., along the arrow 108 in the Fig. 1) into the combustion chambers 110 and thus into the exhaust tract 130. Thus, at least one of these two venting paths is at least partially blocked or clogged, for example by soot particles, a defective oil separator, a crushed line, or a clogged intake air filter.

[0042] In the in the Fig. In an advantageous and exemplary embodiment according to FIG. 2, steps 250 and 260 are each followed by a step 270 in which the exhaust gas mass flow is determined. This can be done, for example, by means of an air mass meter arranged in the intake manifold 102 or via an air path model calculated in the engine control system.

[0043] In a subsequent step 280, the hydrogen content present in the crankcase 120 is determined based on the hydrogen content in the exhaust gas determined in step 230 and the exhaust gas mass flow determined in step 270. In particular, the hydrogen content in the crankcase 120 can be determined by correlating the hydrogen content in the exhaust gas determined in step 230 and the exhaust gas mass flow determined in step 270.

[0044] In a subsequent step 290, a check is performed to determine whether the hydrogen content in the crankcase 120 determined in step 280 exceeds a predetermined hydrogen content threshold. If it is determined in step 290 that the hydrogen content in the crankcase 120 determined in step 280 exceeds the predetermined hydrogen content threshold, such as 3%, the method proceeds to step 292, where an increased risk of explosion is determined. In step 292, an alarm signal can be output to the operator of the hydrogen internal combustion engine 100, alerting the operator that there is an increased risk of explosion. At the same time or subsequently, active venting of the crankcase 120 can occur as a countermeasure.

[0045] If it is determined in step 290 that the hydrogen content in the crankcase 120 determined in step 280 does not exceed the predetermined hydrogen content threshold, such as 3%, the method proceeds to step 294, at which no increased risk of explosion is determined.

[0046] After steps 292 and 294, the process of Fig. 2 at step 300.

Claims

[1] A method for monitoring the ventilation of a crankcase (120) of a hydrogen internal combustion engine (100) having combustion chambers (110) and an oxygen sensor (140) arranged in an exhaust tract (130) of the hydrogen internal combustion engine (100), which oxygen sensor is designed to generate an oxygen signal representative of the oxygen content in the exhaust gas of the hydrogen internal combustion engine (100), the method comprising: - determining a predetermined operating mode of the hydrogen internal combustion engine (100) during which substantially no combustion of an air-hydrogen mixture takes place within the combustion chambers (110), - determining the actual oxygen content in the exhaust gas of the hydrogen internal combustion engine (100) based on the determined predetermined operating mode of the hydrogen internal combustion engine (100), - receiving an oxygen signal from the oxygen sensor (140) during the predetermined operating mode of the hydrogen internal combustion engine (100), - determining the oxygen content in the exhaust gas of the hydrogen internal combustion engine (100) based on the oxygen signal received from the oxygen sensor (140), - forming an oxygen content difference between the determined actual oxygen content and the oxygen content determined based on the oxygen signal received from the oxygen sensor (140), - determining the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) at least partially based on the determined oxygen content difference, and - Determining a functional ventilation of the crankcase (120) when the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content threshold value. [2] Method according to claim 1, wherein the predetermined operating mode of the hydrogen internal combustion engine (100) comprises an overrun fuel cut-off phase of the hydrogen internal combustion engine (100). [3] Method according to one of the preceding claims, further comprising: - Determining a malfunctioning ventilation of the crankcase (120) when the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) determined during the predetermined operating mode of the hydrogen internal combustion engine (100) falls below the predetermined hydrogen content threshold value. [4] The method of claim 3, further comprising: - issuing a warning to the operator of the hydrogen internal combustion engine (100) if a malfunctioning ventilation of the crankcase (120) has been detected. [5] Method according to one of the preceding claims, wherein the predetermined hydrogen content threshold is between 0.3% and 0.6%, preferably 0.5%. [6] Method according to one of the preceding claims, further comprising: - determining an exhaust gas mass flow through the exhaust tract (130) of the hydrogen internal combustion engine (100), and - Determining the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) at least partially based on the received oxygen signal of the oxygen sensor (140) and at least partially based on the determined exhaust gas mass flow through the exhaust tract (130) of the hydrogen internal combustion engine (100). [7] The method of claim 6, further comprising: - determining whether the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content threshold value, and - at least partially venting the crankcase (120) if it has been determined that the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds the predetermined hydrogen content threshold value. [8] The method of claim 7, further comprising: - determining the temperature of the gas mixture in the crankcase (120), wherein the predetermined hydrogen content limit threshold value is predetermined as a function of the determined temperature of the gas mixture in the crankcase (120). [9] A method according to any one of claims 6 to 8, further comprising: - issuing an alarm to the operator of the hydrogen internal combustion engine (100) when it has been determined that the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds the predetermined hydrogen content threshold, the alarm informing the operator that there is an increased risk of explosion of the crankcase (120). [10] Hydrogen internal combustion engine (100) designed to be operated with hydrogen as fuel, comprising: - at least one combustion chamber (110) formed by a piston (114) reciprocating reciprocally within a cylinder (112), - a crankcase (120) in which the piston (114) is at least partially arranged and which is at least partially fluidly connected to the combustion chamber (110) via a gap between the piston (114) and the cylinder (112), - an exhaust tract (130) which is fluidly connected to the at least one combustion chamber (110), - an oxygen sensor (140) arranged in the exhaust tract (130) which is designed to generate an oxygen signal which is representative of the oxygen content in the exhaust gas of the hydrogen internal combustion engine (100), and - a control unit (160) which is designed to carry out a method according to one of the preceding claims for monitoring the ventilation of a crankcase (120) of the hydrogen internal combustion engine (100). [11] Hydrogen internal combustion engine (100) according to claim 10, further comprising: - an intake pipe (102) fluidly connected to the at least one combustion chamber (110) and configured to supply air to the at least one combustion chamber (110) for the combustion of an air-hydrogen mixture, and - a vent line (124) which fluidly connects the crankcase (120) to the intake pipe (102). [12] Hydrogen internal combustion engine (100) according to claim 11, further comprising: - a ventilation line (128) which fluidly connects the crankcase (120) to the intake pipe (102), and - a ventilation pump (129) arranged in the ventilation line (128) and designed to pump air from the intake pipe (102) into the crankcase (120) for flushing the crankcase (120) with air.

Images