Method for monitoring hydrogen internal combustion engine crankcase ventilation and hydrogen internal combustion engine

Abstract

This invention relates to a method for monitoring crankcase (120) ventilation of a hydrogen internal combustion engine (100) and a hydrogen internal combustion engine (100) having a combustion chamber (110) and a gas sensor (140) disposed in an exhaust passage (130) of the hydrogen internal combustion engine (100), the gas sensor being configured to generate a gas signal representing the hydrogen or oxygen content in the exhaust gas of the hydrogen internal combustion engine (100). The method according to the invention includes: determining a predetermined operating mode of the hydrogen internal combustion engine (100) in which combustion of an air-hydrogen mixture substantially does not occur in the combustion chamber (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 in part on the received gas signal; and determining that the crankcase (120) ventilation function is normal when the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content threshold.

Description

Technical Field

[0001] This invention relates to a method for monitoring crankcase ventilation in a hydrogen internal combustion engine and a hydrogen internal combustion engine, particularly a hydrogen internal combustion engine with crankcase ventilation. Background Technology

[0002] For internal combustion engines with a closed crankcase (piston), pressure changes deviating from atmospheric pressure occur not only in the working chamber but also below the piston. This is partly due to volume changes caused by the piston during operation and partly due to gases accumulating in the crankcase during operation.

[0003] In internal combustion engines, blow-by gas, or "blow-by," will inevitably occur in the crankcase. Because the crankcase forms a closed space, pressure will continuously rise without ventilation. To avoid this, blow-by gas, containing combustion products and unburned hydrogen, can be selectively vented from the crankcase. Ideally, the relative crankcase pressure should be in the range of a slight negative pressure of approximately -2 mbar, as under these conditions, the engine is less likely to "leak" lubricating oil. If the negative pressure is significantly greater (this value varies from engine to engine and depends on the design of the sealing assembly), there is a risk that air carrying contaminant particles and / or pure hydrogen can be drawn in through the shaft seal rings and seals on the crankcase. This leads to increased wear on internal components. During ventilation, oil droplets generated by rotating parts will also inevitably be carried out of the crankcase.

[0004] During the operation of a hydrogen internal combustion engine, especially during the fuel cut-off phase, due to the high pressure in the intake manifold, the gas trapped in the crankcase (especially the pure hydrogen present therein) can at least partially bypass the piston and re-enter the combustion chamber, thus entering the exhaust passage of the hydrogen internal combustion engine.

[0005] Furthermore, ventilation ducts may be blocked, broken, or disconnected from the intake system. Consequently, crankcase ventilation is restricted, allowing contaminants and pure hydrogen to be released unimpeded into the environment. Therefore, the hydrogen content in the exhaust gas and / or crankcase of the hydrogen internal combustion engine, as well as the proper functioning of crankcase ventilation, should be monitored. When normal crankcase ventilation is lacking, pure hydrogen can accumulate in the crankcase and / or be released unimpeded into the environment in the event of a leak. Additionally, there is a risk of ignition of the air-hydrogen mixture if the hydrogen content in the exhaust gas and / or crankcase exceeds the temperature-related explosion limits.

[0006] DE102021213901B3 discloses a method for monitoring crankcase ventilation in a fossil fuel internal combustion engine. The known method includes: determining a predetermined operating mode of the internal combustion engine in which combustion of the air-fuel mixture is substantially absent in the combustion chamber; determining the nitrogen oxide content in the exhaust gas of the internal combustion engine during the predetermined operating mode using an exhaust gas sensor; and determining that the crankcase ventilation function is normal when the nitrogen oxide value determined during the predetermined operating mode exceeds a predetermined nitrogen oxide threshold. Summary of the Invention

[0007] The fundamental objective of this invention is to determine and inspect the proper functioning of crankcase ventilation in hydrogen internal combustion engines in a simple and low-cost manner.

[0008] This task is accomplished by the method according to independent claim 1 and the hydrogen internal combustion engine according to independent claim 12. Advantageous improvements are given in the dependent claims.

[0009] The fundamental concept upon which this invention is based is that, during a predetermined operating mode in which combustion of the air-hydrogen mixture does not occur in the combustion chamber of the internal combustion engine, crankcase ventilation is monitored by a gas sensor located in the exhaust passage of the internal combustion engine. Specifically, during the aforementioned predetermined operating mode, exhaust gases trapped in the crankcase may re-enter the combustion chamber and exhaust passage via ventilation ducts and / or as so-called blow-by gases, and can therefore be detected (directly or indirectly) by a gas signal located in the exhaust passage. If the gas sensor, which is already located and present in the exhaust passage, generates a gas signal indicating a hydrogen content above a predetermined hydrogen content threshold during the predetermined operating mode of the hydrogen internal combustion engine, it can be inferred that the crankcase ventilation is normal and functioning properly, because the ventilation path from the crankcase to the combustion chamber and thus to the exhaust passage is unobstructed. However, if the gas signal from the gas sensor shows a hydrogen content below the predetermined hydrogen content threshold during these predetermined operating modes of the hydrogen internal combustion engine, it can be inferred that the crankcase ventilation is malfunctioning. In particular, it can be determined at this time that the ventilation path from the crankcase to the exhaust passage is at least partially blocked or obstructed.

[0010] Therefore, according to a first aspect of the invention, a method for monitoring crankcase ventilation of a hydrogen internal combustion engine is disclosed, the hydrogen internal combustion engine having a combustion chamber and a gas sensor disposed in the exhaust passage of the hydrogen internal combustion engine, the gas sensor being configured to generate a gas signal representing the hydrogen content or oxygen content in the exhaust gas of the hydrogen internal combustion engine. The method according to the invention includes: determining a predetermined operating mode of the hydrogen internal combustion engine in which combustion of the air-hydrogen mixture is substantially absent in the combustion chamber; receiving a gas signal from the gas sensor during the predetermined operating mode of the hydrogen internal combustion engine; determining the hydrogen content in the exhaust gas of the hydrogen internal combustion engine based at least in part on the received gas signal; and determining that the crankcase ventilation function is normal when the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine exceeds a predetermined hydrogen content threshold. Preferably, the hydrogen signal representing the determined hydrogen content can be processed, for example, using a filter, such as a low-pass filter. This processing can be performed in the signal domain. Furthermore, it is advantageous that the signal processing using a suitable filter is performed subsequently.

[0011] Therefore, 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 ventilation from the crankcase to the exhaust passage of the hydrogen internal combustion engine is unobstructed. If there is a blockage, the determined hydrogen content will be lower than the predetermined hydrogen content threshold because hydrogen accumulated in the crankcase will no longer be able to enter the exhaust passage during the predetermined operating mode.

[0012] In a preferred embodiment of the method of the present invention, the gas sensor is a hydrogen sensor, and the gas signal is a hydrogen signal representing the hydrogen content in the exhaust gas of a hydrogen internal combustion engine.

[0013] In an alternative embodiment, the gas sensor is an oxygen sensor, and the gas signal is an oxygen signal representing the oxygen content in the exhaust gas of a hydrogen internal combustion engine.

[0014] In such an alternative embodiment, the method of the present invention further includes: determining the oxygen content in the exhaust gas of the hydrogen internal combustion engine based on an oxygen signal received from an oxygen sensor; determining the actual oxygen content in the exhaust gas of the hydrogen internal combustion engine based on a predetermined operating mode of the determined hydrogen internal combustion engine; and 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. Here, the determination of the hydrogen content in the exhaust gas of the hydrogen internal combustion engine is based at least in part on the determined oxygen content difference.

[0015] This utilizes the fact that hydrogen present in the exhaust gas acts as an enrichment agent. That is, hydrogen reacts with oxygen present in the exhaust gas to form water on the electrodes and catalytic surface of the oxygen sensor. Therefore, the oxygen content indicated by the oxygen sensor is lower than the actual oxygen content because hydrogen present in the exhaust gas reacts with a corresponding proportion of oxygen. The difference between the actual oxygen content and the oxygen content indicated by the oxygen sensor can characterize the hydrogen content in the exhaust gas because there is a correlation between changes in the oxygen signal and the hydrogen concentration, thus determining the hydrogen content in the exhaust gas. However, since the actual oxygen content is known in these predetermined operating modes, for example, approximately 20.9% in air, according to the present invention, the hydrogen content in the exhaust gas can be determined based on the oxygen signal from the oxygen sensor. The hydrogen content is determined based on the determined difference in oxygen content, preferably using characteristic curves, characteristic plots, correction functions, transfer functions, and / or other mathematical functions.

[0016] In a preferred embodiment of the method of the present invention, after determining the predetermined operating mode of the hydrogen internal combustion engine, a hydrogen signal is received only after a predetermined time period. The predetermined time period is preferably about 3 seconds, more preferably about 1 second. For example, this ensures that the exhaust gas produced by the combustion of the air-hydrogen mixture in the combustion chamber has been completely discharged from the combustion chamber and has flowed through the oxygen sensor, so that during the predetermined operating mode, the gas mixture measured by the oxygen sensor must mostly originate from the crankcase and intake manifold.

[0017] In an alternative embodiment, it is also preferable to determine the hydrogen content only when the air mass integral in the exhaust passage exceeds a predetermined air mass integral threshold. Specifically, the time until the gas sensor can measure the exhaust gas from the crankcase depends on the mass flow rate and the volume of the exhaust passage. Therefore, in such an alternative embodiment, it is advantageous to determine the hydrogen content only when the air mass integral in the exhaust passage exceeds a predetermined air mass integral threshold. Furthermore, the gas sensor requires a certain amount of time to stabilize to the corresponding measurement value.

[0018] In an advantageous embodiment, the method of the invention further includes determining a crankcase ventilation malfunction when 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, is below a predetermined hydrogen content threshold. In such an advantageous embodiment, it is preferred that, upon determining a crankcase ventilation malfunction, the method of the invention further includes issuing a warning to the operator of the hydrogen internal combustion engine.

[0019] Preferably, the predetermined hydrogen content threshold is between about 0.3% and about 0.6%, more preferably about 0.5%.

[0020] In another advantageous embodiment, the method of the invention further includes: determining the exhaust gas mass flow rate through the exhaust passage of the hydrogen internal combustion engine; and determining the hydrogen content in the crankcase of the hydrogen internal combustion engine based at least in part on the received gas signal des Gassignal and at least in part on the exhaust gas mass flow rate determined through the exhaust passage 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 rate. This correlation can be provided, for example, in the form of a lookup table and / or a mathematical mapping.

[0021] Preferably, according to such a preferred embodiment, the method of the present invention further includes: determining that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds a predetermined hydrogen content limit threshold; and when it is determined that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds the predetermined hydrogen content limit threshold, ventilating the crankcase at least partially.

[0022] In a particularly preferred manner, the method of the present invention further includes determining the temperature of the gas mixture in the crankcase. The predetermined hydrogen content limit threshold can then be predetermined based on the determined temperature of the gas mixture in the crankcase.

[0023] In another advantageous embodiment, the method of the invention further includes issuing an alarm to the operator of the hydrogen internal combustion engine when it is determined that the hydrogen content in the crankcase of the hydrogen internal combustion engine exceeds a predetermined hydrogen content limit threshold. The alarm informs the operator that there is an increased risk of explosion in the crankcase.

[0024] According to another aspect of the invention, a hydrogen internal combustion engine is disclosed, configured to operate using hydrogen as fuel. The hydrogen internal combustion engine according to the invention comprises at least one combustion chamber formed by a piston reciprocating within a cylinder; a crankcase in which the piston is at least partially disposed and in fluid communication with the combustion chamber via a gap between the piston and the cylinder; an exhaust passage in fluid communication with the at least one combustion chamber; a gas sensor disposed in the exhaust passage, configured to generate a gas signal representing the hydrogen or oxygen content in the exhaust gas of the hydrogen internal combustion engine; and a control unit configured to perform a method according to the invention for monitoring crankcase ventilation of a hydrogen internal combustion engine.

[0025] Preferably, the hydrogen internal combustion engine according to the invention further includes an intake manifold fluidly connected to the at least one combustion chamber and configured to supply air for combustion of the air-hydrogen mixture to the at least one combustion chamber, and a ventilation duct fluidly connected to the crankcase and the intake manifold.

[0026] In another preferred embodiment, the hydrogen internal combustion engine according to the invention further includes a ventilation line that fluidly communicates the crankcase with the intake manifold, and a ventilation pump disposed in the ventilation line, the ventilation pump being configured to pump air from the intake manifold into the crankcase to flush the crankcase with air. Attached Figure Description

[0027] Those skilled in the art will understand more features and objectives of the invention by practicing this disclosure and reviewing the accompanying drawings, wherein: Figure 1 shows a schematic diagram of the vehicle's hydrogen internal combustion engine, and Figure 2 shows an exemplary flowchart of the method of the present invention for monitoring crankcase ventilation of the hydrogen internal combustion engine of Figure 1. Detailed Implementation

[0028] Within the scope of this disclosure, the term "Wasserstoff-Brennkraftmaschine" describes an internal combustion engine that operates using hydrogen as fuel. A hydrogen internal combustion engine converts chemical energy into mechanical work and heat. It is based on the hydrogen-oxygen reaction (combustion of hydrogen) in a reciprocating or rotary piston internal combustion engine. Most commonly, reciprocating piston engines operating according to the Otto principle (= external ignition) are used. However, according to the present invention, hydrogen internal combustion engines operating according to the diesel principle (= compression ignition) are also included.

[0029] Figure 1 shows a schematic diagram of a hydrogen internal combustion engine 100 in a vehicle. The hydrogen internal combustion engine 100 has an intake manifold (or air inlet pipe) 102 and a combustion chamber 110 connected thereto (in Figure 1, only one of the four combustion chambers 110 is labeled with reference numerals). Intake air can enter the combustion chamber 110 via the intake manifold 102, where it can mix with and burn hydrogen as fuel in a known manner. The direction of intake air flow is indicated by arrow 104.

[0030] Combustion chamber 110 is formed, in particular, by cylinder 112 and piston 114 reciprocating therein, thereby causing the volume of combustion chamber 110 to change over time. Piston 114 is at least partially arranged in crankcase 120 and mechanically coupled to crankshaft 122 arranged therein, as is known in the prior art.

[0031] Combustion chamber 110 is in fluid communication with exhaust passage 130, through which exhaust gases produced by the combustion of the air-hydrogen mixture in combustion chamber 110 can be discharged into the environment. Exhaust passage 130 is described here only as the portion of the hydrogen internal combustion engine 100 specifically used for exhaust gas discharge.

[0032] A gas sensor 140 is disposed in the exhaust passage 130. This gas sensor is configured to generate a gas signal indicating the hydrogen or oxygen content in the exhaust gas located downstream of the combustion chamber 110. The gas sensor 140 may be a hydrogen sensor based on the principle of thermal conductivity measurement, configured to determine the hydrogen content. The hydrogen sensor 140 may also be any other hydrogen sensor known in the art configured to determine the hydrogen content in a gas mixture.

[0033] Alternatively, the gas sensor 140 can also be an oxygen sensor configured to generate an oxygen signal representing the oxygen content in the exhaust gas of the hydrogen internal combustion engine 100. The oxygen sensor 140 can be a binary lambda probe, a linear lambda probe, a nitrogen oxide sensor, or any other sensor whose signal can be used to determine the oxygen content. The oxygen sensor 140 cannot directly detect the hydrogen content. Instead, the oxygen content measured by the oxygen sensor 140 is affected by the hydrogen content in the exhaust gas, as the present hydrogen acts as a enrichment gas and reacts with the oxygen present in the exhaust gas to form water on the electrode and catalytic surfaces of the oxygen sensor 140. Therefore, the oxygen content determined by the oxygen sensor 140 is lower than the actual oxygen content present in the exhaust gas. The difference between the actual oxygen content and the oxygen content determined by the oxygen sensor 140 can be correlated with the hydrogen content in the exhaust gas. To determine the oxygen content difference, the actual oxygen content in the exhaust gas during the predetermined operating mode must be known. This is the case, for example, during the fuel cut-off phase of the hydrogen internal combustion engine 100, because during these phases no fuel is injected, but only intake air is forced through the combustion chamber 110 and exhaust passage 130. Under these conditions, the oxygen content can be assumed to be approximately 20.9%, corresponding to the oxygen content in the air. The determined oxygen content difference can be correlated with the hydrogen content.

[0034] In addition, a control unit 160 is provided, which is in communication connection with the gas sensor 140 and is configured to receive the gas signal generated by the gas sensor 140 and at least partially control the operation of the hydrogen internal combustion engine 100.

[0035] During operation of the hydrogen internal combustion engine 100, pressure changes deviating from atmospheric pressure occur not only in the combustion chamber 110 but also below the piston 114. This is due, in part, to volume changes caused by the operating piston 114, and in part to exhaust gases accumulating in the crankcase 120 during operation. In particular, exhaust gases from the combustion chamber 110 can enter the crankcase 120 through the gap between the cylinder 112 and the piston 114, as schematically indicated by arrow 106 in Figure 1.

[0036] To prevent these so-called blow-by gases from being released unimpeded into the atmosphere, a ventilation duct 124 is provided, which fluidly connects the crankcase 120 to the intake manifold 102. A control valve 126 is provided in the ventilation duct 124, which controls the active ventilation of the crankcase 120 to the intake manifold 102. The control valve 126 is preferably a pressure regulating valve capable of automatically controlling or regulating the pressure inside the crankcase 120. Alternatively, the pressure in the crankcase 120 can also be set by means of a mechanical regulating valve (not shown in Figure 1) in the intake manifold 102. In particular, the exhaust gases collected in the crankcase 120 can be delivered to the combustion chamber 110 in subsequent working cycles and thus to the exhaust passage 130, where they are released into the environment in a controlled manner.

[0037] In the exemplary embodiment shown in Figure 1, the hydrogen internal combustion engine 100 also includes a ventilation line 128 that fluidly connects the crankcase 120 to the intake manifold 102. A ventilation pump 129 is disposed in the ventilation line 128, by means of which the crankcase 120 is controlled to receive active ventilation from the intake manifold 102. The ventilation pump 129 is specifically configured to pump air from the intake manifold 102 into the crankcase 120 when it is determined that the hydrogen content inside the crankcase 120 exceeds a predetermined hydrogen content threshold and thus poses an increased explosion hazard. By blowing air into the crankcase 120, the hydrogen content therein can be reduced, thereby reducing the explosion hazard.

[0038] According to the embodiment shown in Figure 1, blow-by gas is introduced into the intake manifold 102 via the ventilation duct 124. Due to the negative pressure in the intake manifold 102, a negative pressure is also generated in the crankcase 120 under most operating conditions of the internal combustion engine 100.

[0039] An exemplary embodiment of the present invention for monitoring the crankcase ventilation function of the hydrogen internal combustion engine 100 of FIG1 is described below with reference to FIG2.

[0040] The method in Figure 2 begins at step 200 and then proceeds to step 210, in which it is determined whether the hydrogen internal combustion engine 100 is in a predetermined operating mode during which combustion of the air-hydrogen mixture does not occur in the combustion chamber 110. For example, a predetermined operating mode could be a fuel cut-off phase of the hydrogen internal combustion engine 100. The method remains at step 210 until a predetermined operating mode is determined.

[0041] If a predetermined operating mode of the hydrogen internal combustion engine 100 is determined at step 210, the method proceeds to step 220, in which a gas signal is generated by gas sensor 140 and received by control unit 160. In 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. When a hydrogen sensor is used as gas sensor 140, this can be done directly based on the hydrogen signal. Alternatively, as described above, when an oxygen sensor is used as gas sensor, the hydrogen content can also be determined indirectly based on the oxygen signal.

[0042] In subsequent step 240, it is determined whether the hydrogen content determined in step 230 exceeds a predetermined hydrogen content, for example, 0.5%. Preferably, after determining the predetermined operating mode of the hydrogen internal combustion engine 100, a predetermined time period of approximately 3 seconds, preferably approximately 1 second, can be waited before executing step 240. This ensures that at the moment the gas signal is generated, the exhaust gas produced by combustion in the combustion chamber 110 has already flowed through the gas sensor 140. Therefore, the exhaust gas measured in step 220 should be the exhaust gas vented from the crankcase 120.

[0043] If, in step 240, it is determined that the hydrogen content determined in step 230 exceeds a predetermined hydrogen content threshold, the method proceeds to step 250, in which the crankcase ventilation function is diagnosed as normal. Specifically, exceeding the predetermined hydrogen content threshold can be interpreted as exhaust gases containing hydrogen trapped in the crankcase 120 being able to flow into the combustion chamber 110 and thus into the exhaust passage 130 via ventilation duct 124 or around piston 114 (i.e., in the direction of arrow 108 in Figure 1). Therefore, both ventilation paths are substantially unobstructed and substantially unobstructed.

[0044] However, if it is determined in step 240 that the hydrogen content determined in step 230 does not exceed, i.e., is below a predetermined hydrogen threshold, the method proceeds to step 260, in which a malfunction or abnormality in crankcase ventilation is diagnosed. Specifically, being below the predetermined hydrogen threshold can be interpreted as exhaust gases trapped in crankcase 120 not flowing into combustion chamber 110 and thus exhaust passage 130 as expected via ventilation duct 124 or around piston 114 (i.e., in the direction of arrow 108 in Figure 1). Therefore, at least one of these two ventilation paths is at least partially blocked or clogged, for example due to soot particles, a damaged oil separator, compressed tubing, or a clogged intake air filter.

[0045] In the advantageous and exemplary embodiment shown in Figure 2, steps 250 and 260 are each followed by a step 270 in which the exhaust gas mass flow rate is determined. This can be done, for example, by means of an air mass flow meter arranged in the intake manifold 102 or by means of an air path model calculated in engine control.

[0046] In subsequent step 280, the hydrogen content present in crankcase 120 is determined based on the hydrogen content in the exhaust gas determined in step 230 and the exhaust gas mass flow rate determined in step 270. Specifically, the hydrogen content in crankcase 120 can be determined by correlating the hydrogen content in the exhaust gas determined in step 230 with the exhaust gas mass flow rate determined in step 270.

[0047] In subsequent step 290, it is checked whether the hydrogen content in crankcase 120, as determined in step 280, exceeds a predetermined hydrogen content limit threshold. If step 290 determines that the hydrogen content in crankcase 120, as determined in step 280, exceeds the predetermined hydrogen content limit threshold, for example, 3%, the method proceeds to step 292, in which an increased explosion hazard is identified. In step 292, an alarm signal may be output to the operator of the hydrogen internal combustion engine 100 to indicate the existence of an increased explosion hazard. Simultaneously or subsequently, active ventilation of crankcase 120 may be performed as a countermeasure.

[0048] If it is determined in step 290 that the hydrogen content in crankcase 120, as determined in step 280, does not exceed a predetermined hydrogen content limit threshold, such as 3%, then the method proceeds to step 294, in which it is determined that there is no increased risk of explosion.

[0049] After steps 292 and 294, the method of Figure 2 ends at step 300.

Claims

1. A method for monitoring the ventilation of a crankcase (120) of a hydrogen internal combustion engine (100), the hydrogen internal combustion engine (100) having a combustion chamber (110) and a gas sensor (140) disposed in an exhaust passage (130) of the hydrogen internal combustion engine (100), the gas sensor (140) being configured to generate a gas signal representing the hydrogen content or oxygen content in the exhaust gas of the hydrogen internal combustion engine (100), characterized in that, The method includes: determining a predetermined operating mode of the hydrogen internal combustion engine (100) in which combustion of the air-hydrogen mixture substantially does not occur in the combustion chamber (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 in part on the received gas signal; and determining that the ventilation function of the crankcase (120) is normal when the determined hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content threshold.

2. The method according to claim 1, wherein the gas sensor is a hydrogen sensor (140), and the gas signal is a hydrogen signal representing the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100).

3. The method according to claim 1, wherein the gas sensor is an oxygen sensor (140), and the gas signal is an oxygen signal representing the oxygen content in the exhaust gas of the hydrogen internal combustion engine (100).

4. The method according to claim 3, further comprising: Based on the oxygen signal received from the oxygen sensor (140), the oxygen content in the exhaust gas of the hydrogen internal combustion engine (100) is determined. Based on the predetermined operating mode of the hydrogen internal combustion engine (100) determined, the actual oxygen content in the exhaust gas of the hydrogen internal combustion engine (100) is determined, and an oxygen content difference is formed between the determined actual oxygen content and the oxygen content determined based on the oxygen signal received from the oxygen sensor (140). The determination of the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) is at least partially based on the determined oxygen content difference.

5. The method according to any of the preceding claims, wherein after determining the predetermined operating mode of the hydrogen internal combustion engine (100), a predetermined time period is elapsed before receiving the hydrogen signal.

6. The method according to claim 5, wherein the predetermined time period is approximately 3 seconds, preferably approximately 1 second.

7. The method according to any one of the preceding claims, wherein the predetermined operating mode of the hydrogen internal combustion engine (100) includes a fuel cut-off phase of the hydrogen internal combustion engine (100).

8. The method according to any one of the preceding claims, further comprising: When the hydrogen content in the exhaust gas of the hydrogen internal combustion engine (100) is lower than the predetermined hydrogen content threshold during the predetermined operating mode of the hydrogen internal combustion engine (100), the ventilation function of the crankcase (120) is determined to be abnormal.

9. The method according to claim 8, further comprising: When a malfunction is detected in the crankcase (120) ventilation function, a warning is issued to the operator of the hydrogen internal combustion engine (100).

10. The method according to any one of the preceding claims, wherein the predetermined hydrogen content threshold is between about 0.3% and about 0.6%, and preferably about 0.5%.

11. The method according to any one of the preceding claims, further comprising: The mass flow rate of exhaust gas through the exhaust passage (130) of the hydrogen internal combustion engine (100) is determined, and the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) is determined based at least in part on the gas signal received from the gas sensor (140) and at least in part on the mass flow rate of exhaust gas determined through the exhaust passage (130).

12. The method of claim 11, further comprising: When it is determined that the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds a predetermined hydrogen content limit threshold, the crankcase (120) is ventilated at least partially when the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds the predetermined hydrogen content limit threshold.

13. The method of claim 12, further comprising: The temperature of the gas mixture in the crankcase (120) is determined, wherein the predetermined hydrogen content limit threshold is predetermined based on the gas mixture temperature determined in the crankcase (120).

14. The method according to any one of claims 11 to 13, further comprising: When it is determined that the hydrogen content in the crankcase (120) of the hydrogen internal combustion engine (100) exceeds the predetermined hydrogen content limit threshold, an alarm is issued to the operator of the hydrogen internal combustion engine (100) to indicate that there is an increased risk of explosion in the crankcase (120).

15. A hydrogen internal combustion engine (100) configured to operate using hydrogen as fuel, comprising: At least one combustion chamber (110) formed by a piston (114) reciprocating within a cylinder (112), a crankcase (120) wherein the piston (114) is at least partially disposed, and the crankcase (120) is at least partially in fluid communication with the combustion chamber (110) via a gap between the piston (114) and the cylinder (112), an exhaust passage (130) in fluid communication with the at least one combustion chamber (110), a gas sensor (140) disposed in the exhaust passage (130) and configured to generate a gas signal representing the hydrogen or oxygen content in the exhaust gas of the hydrogen internal combustion engine (100), and a control unit (160) configured to perform the method according to any one of the preceding claims to monitor the ventilation of the crankcase (120) of the hydrogen internal combustion engine (100).

16. The hydrogen internal combustion engine (100) according to claim 15, further comprising: An intake manifold (102) in fluid communication with the at least one combustion chamber (110) and configured to supply air to the at least one combustion chamber (110) for combustion of an air-hydrogen mixture, and a ventilation manifold (124) in fluid communication between the crankcase (120) and the intake manifold (102).

17. The hydrogen internal combustion engine (100) according to claim 16, further comprising: A ventilation line (128) that fluidly communicates the crankcase (120) with the intake manifold (102), and a ventilation pump (129) disposed in the ventilation line (128) configured to pump air from the intake manifold (102) to the crankcase (120) for flushing the crankcase (120) with air.

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