Hydrogen engine
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-01-24
- Publication Date
- 2026-08-05
Smart Images
Figure 2026126691000001_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a hydrogen engine.
Background Art
[0002] Patent Document 1 discloses an internal combustion engine. The internal combustion engine includes a cylinder block, a crankcase connected to the lower part of the cylinder block, and a cylinder head connected to the upper part of the cylinder block. The internal combustion engine has a plurality of communication passages extending from the crankcase to the cylinder head.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the case of a hydrogen engine, a part of the hydrogen injected into the combustion chamber may leak into the crankcase as blow-by gas and accumulate in the crankcase and the cylinder head. The accumulated hydrogen may ignite and cause a flame. The flame generated in one of the crankcase and the cylinder head may flow into the other through a plurality of communication passages. Along with this, it is desirable to avoid an excessive pressure increase caused by the combustion of hydrogen.
Means for Solving the Problems
[0005] According to one aspect of the present disclosure, a hydrogen engine is provided comprising a cylinder block, a crankcase connected to the lower part of the cylinder block, and a cylinder head connected to the upper part of the cylinder block, wherein a plurality of connecting passages are provided that connect the space in the crankcase and the space in the cylinder head, and one or more of the plurality of connecting passages is narrower than one or more of the remaining plurality of connecting passages.
[0006] According to one aspect of the present disclosure, a hydrogen engine is provided comprising a cylinder block, a crankcase connected to the lower part of the cylinder block, and a cylinder head connected to the upper part of the cylinder block, wherein a plurality of connecting passages are provided that connect the space in the crankcase and the space in the cylinder head, and one or more of the plurality of connecting passages have an opening to the space in the cylinder head located above the oil level in the cylinder head, while one or more of the remaining connecting passages have an opening to the space in the cylinder head located below the oil level in the cylinder head. [Effects of the Invention]
[0007] The above configuration makes it easier to suppress the excessive pressure increase mentioned above. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a diagram showing a hydrogen engine according to one embodiment. [Figure 2] Figure 2 is a diagram illustrating the propagation speed of flames. [Figure 3] (a) is a diagram showing the action in a comparative example, and (b) is a diagram showing the action in the hydrogen engine shown in Figure 1. [Modes for carrying out the invention]
[0009] A hydrogen engine according to one embodiment will be described below with reference to the drawings. <Configuration of Hydrogen Engine 100> Referring to Figure 1, the configuration of the hydrogen engine 100 will be described. The hydrogen engine 100 comprises a cylinder block 10, a crankcase 12 connected to the lower part of the cylinder block 10, and a cylinder head 14 connected to the upper part of the cylinder block 10. A ventilation case 14a is provided for the cylinder head 14.
[0010] The cylinder block 10 has cylinders 34. A piston 36 reciprocates inside the cylinders 34. An intake passage 30 and an exhaust passage 32 are connected to the cylinders 34. The intake passage 30 includes, from upstream, an air cleaner 38, a compressor 40a of the turbocharger 40, an intercooler 42, a throttle valve 44, and an intake manifold 46. The turbine wheel 40b of the turbocharger 40 is located in the exhaust passage 32.
[0011] A blow-by gas passage 50 extends from the crankcase 12 to the intake manifold 46. The blow-by gas passage 50 extends inside the cylinder block 10, inside the cylinder head 14, and inside the ventilation case 14a. A PCV (Positive Crankcase Ventilation) valve 48 is provided in the blow-by gas passage 50 between the intake manifold 46 and the ventilation case 14a. The PCV valve 48 adjusts the amount of blow-by gas flowing through the blow-by gas passage 50.
[0012] The return passage 52 extends from the point between the air cleaner 38 and the compressor 40a in the intake passage 30 to the ventilation case 14a. The ventilation case 14a and the cylinder head 14 are in communication. Multiple communication passages 20 are provided that connect the space inside the crankcase 12 and the space inside the cylinder head 14.
[0013] <Configuration of multiple connecting passages 20> Multiple connecting passages 20 include connecting passages 20a and connecting passages 20b. Connecting passage 20a has an opening 22a to a space within the cylinder head 14. The opening 22a is located above the oil level OS within the cylinder head 14. Connecting passage 20a is disposed outside the cylinder block 10. Connecting passage 20a is a pipe or hose. Connecting passage 20b has an opening 22b to a space within the cylinder head 14. The opening 22b is located below the oil level OS within the cylinder head 14. Connecting passage 20b is provided inside the cylinder block 10. Connecting passage 20b is a passage for oil sent to the components in the cylinder head 14 to return to the crankcase 12. The number of connecting passages 20a may be one or more. The number of connecting passages 20b may be one or more.
[0014] As shown in Figure 1, passage 20a is narrower than passage 20b. In other words, one or more of the multiple passages 20 are narrower than one or more of the remaining passages 20. <Operation of this embodiment> As the intake manifold 46 becomes negatively pressurized, the PCV valve 48 opens. This causes air to flow in the following order: recirculation passage 52, ventilation case 14a, cylinder head 14, connecting passages 20a and 20b, crankcase 12, and blow-by gas passage 50. This allows blow-by gas stored in the crankcase 12 to flow into the intake passage 30.
[0015] The hydrogen engine 100 comprises a cylinder block 10, a crankcase 12 connected to the lower part of the cylinder block 10, and a cylinder head 14 connected to the upper part of the cylinder block 10. Multiple connecting passages 20 are provided that connect the space within the crankcase 12 and the space within the cylinder head 14. One or more of the multiple connecting passages 20 are narrower than one or more of the remaining multiple connecting passages 20.
[0016] The propagation speed U of the flame surface in the multiple connecting passages 20 increases as the diameter of the connecting passages 20 narrows. Referring to FIG. 2, the propagation speed U, which is the speed at which the flame surface moves, will be described. When a flame is generated by the ignition of hydrogen stored as blow-by gas, a flame surface, which is the boundary between the burned gas and the unburned gas, is formed. The propagation speed U, which is the speed at which the flame surface moves, is the sum of the turbulent combustion speed St and the advection speed Adv caused by the expansion of the burned gas.
[0017] Referring to FIGS. 3(a) and (b), the reason why the propagation speed U of the flame surface in the communication passage 20 increases as the diameter of the communication passage 20 becomes smaller will be explained. FIG. 3(a) shows a comparative example in which the diameters of the communication passages 20A and 20B are the same. The thick curve in the crankcase 12 of FIG. 3(a) indicates the current flame surface. The thick curve in the cylinder head 14 of FIG. 3(a) indicates the flame surface that has moved from the crankcase 12 to the cylinder head 14. FIG. 3(b) shows the present embodiment in which the communication passage 20a is narrower than the communication passage 20b. The thick curve in the crankcase 12 of FIG. 3(b) indicates the current flame surface. The thick curve in the cylinder head 14 of FIG. 3(b) indicates the flame surface that has moved from the crankcase 12 to the cylinder head 14.
[0018] The case where the flame generated in the crankcase 12 flows into the cylinder head 14 through the communication passages 20a and 20b will be described. When the flame surface spreads in the crankcase 12, the flame surface reaches the location where it opens into the crankcase 12 in the communication passage 20. As described above, the propagation speed U is the sum of the turbulent combustion speed St and the advection speed Adv caused by the expansion of the burned gas. Since the advection speed Adv is caused by the expansion of the burned gas, it becomes faster as the cross-sectional area of the communication passage 20 becomes smaller. Therefore, the propagation speed U of the flame surface in the communication passage 20 increases as the diameter of the communication passage 20 becomes smaller.
[0019] In the comparative example shown in FIG. 3(a), the diameters of the communication passages 20A and 20B are the same. Therefore, it is highly likely that the flame generated in the crankcase 12 reaches the cylinder head 14 almost simultaneously. <000009In contrast, in the present embodiment, the communication passage 20a is narrower than the communication passage 20b. Therefore, the flame moving through the narrow communication passage 20a is more likely to reach the cylinder head 14 earlier than the flame moving through the wide communication passage 20b.
[0021] <Effects of the present embodiment> (1) As described above, since the flame moving through the narrow communication passage 20a is more likely to reach the cylinder head 14 earlier than the flame moving through the wide communication passage 20b, the present embodiment is more likely to suppress an excessive pressure rise compared to the comparative example.
[0022] The reason why the present embodiment is more likely to suppress an excessive pressure rise compared to the comparative example will be explained. The amount of chemical reaction occurring at the flame surface is proportional to the turbulent combustion speed St, the unburned gas density, and the flame area which is the area of the flame surface. In the comparative example, since the flame generated in the space within the crankcase 12 is likely to reach the space within the cylinder head 14 almost simultaneously, as shown in FIG. 3, the flame area is more likely to become larger compared to the present embodiment. The fact that the flame area is more likely to become larger means that the amount of chemical reaction is also more likely to become larger. This means that the pressure rise due to the chemical reaction is also more likely to become larger. Therefore, in the present embodiment, it is more likely to suppress an excessive pressure rise compared to the comparative example.
[0023] [[ID=:13]] The case where the flame generated in the crankcase 12 flows into the cylinder head 14 via the communication passages 20a and 20b has been described above. The same applies to the case where the flame generated in the cylinder head 14 flows into the crankcase 12 via the communication passages 20a and 20b.
[0024] (2) One or more of the plurality of communication passages 20 are narrower than the remaining one or more of the plurality of communication passages 20, and include the communication passage 20a in which the opening 22a into the space within the cylinder head 14 is located above the oil level OS within the cylinder head 14.
[0025] The hydrogen engine 100 described above is equipped with a narrow connecting passage 20a whose opening 22a to the space within the cylinder head 14 is located above the oil level OS within the cylinder head 14. Since the narrow connecting passage 20a has an opening 22a located above the oil level OS within the cylinder head 14, it is less likely that oil will obstruct the propagation of the flame through the narrow connecting passage 20a. Therefore, the possibility of the flame generated in the crankcase 12 reaching the cylinder head 14 almost simultaneously is reduced. Consequently, this configuration makes it easier to suppress excessive pressure rise.
[0026] (3) One or more of the multiple connecting passages 20 is narrower than one or more of the remaining connecting passages 20 and includes a connecting passage 20a located outside the cylinder block 10.
[0027] With the above configuration, the propagation speed U can be easily adjusted by changing the communication passage 20a located outside the cylinder block 10. The propagation speed U can be easily adjusted without changing the internal structure of the cylinder block 10.
[0028] (4) The hydrogen engine 100 comprises a cylinder block 10, a crankcase 12 connected to the lower part of the cylinder block 10, and a cylinder head 14 connected to the upper part of the cylinder block 10. Multiple connecting passages 20 are provided that connect the space in the crankcase 12 to the space in the cylinder head 14. One or more of the multiple connecting passages 20 have an opening 22a to the space in the cylinder head 14 located above the oil level OS in the cylinder head 14. One or more of the remaining multiple connecting passages 20 have an opening 22b to the space in the cylinder head 14 located below the oil level OS in the cylinder head 14.
[0029] In the communication passage 20b where the opening 22b to the space within the cylinder head 14 is located below the oil level OS within the cylinder head 14, oil tends to block the communication passage 20b, reducing the flame propagation speed U. Therefore, with the above configuration, the likelihood of flames generated in the crankcase 12 reaching the cylinder head 14 almost simultaneously is low. Similarly, the likelihood of flames generated in the cylinder head 14 reaching the crankcase 12 almost simultaneously is low. Consequently, it is easier to avoid excessive pressure increases caused by the combustion of hydrogen stored as blow-by gas.
[0030] (5) One or more of the multiple connecting passages 20 include a connecting passage 20a located outside the cylinder block 10, the opening 22a to the space inside the cylinder head 14 being above the oil level OS inside the cylinder head 14.
[0031] With the above configuration, the propagation speed U can be easily adjusted by changing the communication passage 20a located outside the cylinder block 10. The propagation speed U can be easily adjusted without changing the internal structure of the cylinder block 10.
[0032] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.
[0033] In the above embodiment, the opening 22a of the communication passage 20a is located above the oil level OS inside the cylinder head 14. Alternatively, the opening 22a may be located below the oil level OS.
[0034] In the above embodiment, the communication passage 20a is located outside the cylinder block 10. Alternatively, the communication passage 20a may be located inside the cylinder block 10.
[0035] In the above embodiment, the communication passage 20a is narrower than the communication passage 20b. Alternatively, the diameters of the communication passage 20a and the communication passage 20b may be the same. The opening 22a to the space inside the cylinder head 14 is located above the oil level OS inside the cylinder head 14. Therefore, it is easier to avoid a situation in which oil blocks the communication passage 20a, thereby reducing the flame propagation speed U in the communication passage 20a. Therefore, it is unlikely that the flame generated in the crankcase 12 will reach the cylinder head 14 almost simultaneously through the communication passages 20a and 20b. [Explanation of symbols]
[0036] OS... Oil level, 10... Cylinder block, 12... Crankcase, 14... Cylinder head, 20, 20a, 20b... Connecting passages, 22a, 22b... Openings, 100... Hydrogen engine
Claims
1. Cylinder block and A crankcase connected to the lower part of the cylinder block, A hydrogen engine comprising a cylinder head connected to the upper part of the cylinder block, wherein a plurality of connecting passages are provided that connect the space in the crankcase and the space in the cylinder head, and one or more of the plurality of connecting passages is narrower than one or more of the remaining plurality of connecting passages. Hydrogen engine.
2. One or more of the plurality of connecting passages is narrower than one or more of the remaining connecting passages, and includes a connecting passage whose opening to the space within the cylinder head is located above the oil level within the cylinder head. The hydrogen engine according to claim 1.
3. One or more of the plurality of connecting passages is narrower than one or more of the remaining connecting passages and includes a connecting passage located outside the cylinder block. The hydrogen engine according to claim 1 or 2.
4. Cylinder block and A crankcase connected to the lower part of the cylinder block, A hydrogen engine comprising a cylinder head connected to the upper part of the cylinder block, wherein a plurality of connecting passages are provided that connect the space in the crankcase and the space in the cylinder head, and one or more of the plurality of connecting passages have an opening to the space in the cylinder head located above the oil level in the cylinder head, while one or more of the remaining connecting passages have an opening to the space in the cylinder head located below the oil level in the cylinder head. Hydrogen engine.
5. One or more of the aforementioned multiple connecting passages include a connecting passage whose opening to the space within the cylinder head is located above the oil level within the cylinder head and which is disposed outside the cylinder block. The hydrogen engine according to claim 4.