Hydrogen engine

Abstract

To suppress pressure rise in a head space due to combustion of leaked hydrogen.SOLUTION: A hydrogen engine 10 having a plurality of bank 12L and 12R includes head cover 12L and 12R covering a valve mechanism disposed above a cylinder 14 belonging to each bank 36L and 36R and defining head space 34L and 34R therein, an in-engine-body communication path 38 communicating each head space 36L and with a crank chamber 22, and an inter-head communication path 42 communicating two head space and with each other. 36R 36L 36R.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen engine that uses hydrogen as fuel. [Background technology]

[0002] Hydrogen engines that use hydrogen as fuel are known. Patent Document 1 listed below shows a hydrogen gas engine (4). In the hydrogen gas engine (4), a valve train chamber (44) that houses a valve train is connected to a crank chamber (41) via a connecting pipe (46) and a cam chamber (45). Lubricating oil that has lubricated the valve train returns to the crank chamber (41) through the connecting pipe (46). Note that the reference numerals in parentheses above are the reference numerals used in Patent Document 1 listed below and are not related to the reference numerals used in the description of the embodiments of the present application. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-12999 Summary of the Invention [Problem to be solved by the invention]

[0004] In hydrogen engines, some of the hydrogen supplied to the combustion chamber leaks into the crankcase through the gaps in the piston rings. When hydrogen burns in the crankcase, the pressure reaches the head space that houses the valve train, and unburned hydrogen also burns in this head space. In engines with multiple banks, such as V-type engines, the pressure increase caused by combustion in the head space of one bank flows back into the crankcase, where further combustion occurs, further increasing the pressure in the head space of the other bank. This can result in more intense combustion in the head space of the other bank.

[0005] An object of the present invention is to mitigate the effect of a pressure increase in the head space of one bank on a pressure increase in the head space of the other bank. [Means for solving the problem]

[0006] The hydrogen engine of the present invention has a plurality of banks, a head cover that covers the valve trains arranged above the cylinders belonging to each bank and defines a head space therein, an internal engine body communication passage that connects each head space with the crankcase, and an inter-head communication passage that connects one head space with another head space. [Effects of the Invention]

[0007] By transmitting the combustion pressure generated in one head space to the other head space through the inter-head communication passage, a sudden increase in pressure in the other head space caused by combustion in the crank chamber due to combustion in one head space is suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a general configuration of a hydrogen engine according to the present invention; [Figure 2] FIG. 4 is a diagram showing pressure changes in a head space. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a V-type hydrogen engine 10. The basic configuration of the hydrogen engine 10 is similar to that of conventional engines such as gasoline engines. The hydrogen engine 10 is a so-called V-type engine having two banks 12. When it is necessary to distinguish between the two banks, the left bank in the drawing will be referred to as the left bank 12L and the right bank will be referred to as the right bank 12R. Similarly, elements belonging to the respective banks 12L and 12R will be distinguished by adding L and R to the reference numerals of the elements.

[0010] The hydrogen engine 10 has a cylinder block 16 that defines the cylinders 14 arranged in a V-shape with a bank angle of 60°, and an oil pan 18 that is positioned to cover the lower opening of the cylinder block 16. The cylinder block 16 and the oil pan 18 define a crank chamber 22 that houses a crankshaft 20. Pistons 24 reciprocate within the cylinders 14 along the axial direction of the cylinders 14. The pistons 24 and the crankshaft 20 are connected by connecting rods. For simplicity, the detailed structure of the crankshaft 20 and the connecting rod are omitted from Figure 1. The reciprocating motion of the pistons 24 is converted into rotational motion of the crankshaft 20 by the connecting rod and the crankshaft 20.

[0011] A cylinder head 26 is coupled to the cylinder block 16 to cover the open end of each cylinder 14 opposite the crank chamber 22. The cylinder 14, piston 24, and cylinder head 26 together define a combustion chamber 28. The cylinder head 26 is formed with an intake port 30 that introduces an air-fuel mixture into the combustion chamber 28 and an exhaust port 32 that discharges exhaust gas after combustion. An intake valve (not shown) and an exhaust valve (not shown) are disposed at the ends of the intake port 30 and the exhaust port 32 on the combustion chamber 28 side, respectively, and open and close the respective ports at predetermined timing. A valve train (not shown) for driving the intake valve and the exhaust valve is provided on the side of the cylinder head 26 opposite the combustion chamber 28. The valve train may include, for example, a camshaft with a cam, a rocker arm that transmits the movement of the cam to the valve, and a valve spring that biases the valve to a closed position that closes the respective port.

[0012] A head cover 34 that covers the valve train is disposed on the side of the cylinder head 26 opposite the combustion chamber 28. The head cover 34 cooperates with the cylinder head 26 to define a head space 36 therein. An engine body internal communication passage 38 that connects the head space 36 with the crank chamber 22 is formed in the cylinder head 26 and the cylinder block 16. Lubricating oil that lubricates the valve train in the head space 36 passes through the engine body internal communication passage 38 and returns to the crank chamber 22.

[0013] The hydrogen engine 10 has an inter-head communication pipe 40 whose both ends are connected to the left and right head covers 34L, 34R. The inter-head communication pipe 40 defines an inter-head communication passage 42 that connects the left and right head spaces 36L, 36R.

[0014] When the hydrogen engine 10 is operating, hydrogen fuel leaks into the crankcase 22 through the gap between the cylinder 14 and the piston 24, particularly the gap between the piston rings. The hydrogen in the crankcase 22 also accumulates in the head space 36 through the engine body communication passage 38. When hydrogen ignites and burns in the crankcase 22, the pressure in the crankcase 22 rises. This pressure is transmitted through the engine body communication passage 38, compressing the hydrogen-containing gas in the head space 36. The gas in the crankcase 22 is also sent to the head space 36 through the engine body communication passage 38, further increasing the pressure in the head space 36. As a result, when hydrogen burns in one side of the head space 36, for example, the left side head space 36L, the pressure resulting from the combustion flows back into the crankcase 22 through the engine body communication passage 38L. When this pressure increase causes hydrogen to burn again in the crankcase 22, the pressure on the opposite side (the right side head space 36R) rises in the same manner as on the left side. The first combustion in the crankcase 22 and the second combustion in the crankcase 22 resulting from the combustion in the left head space 36L can cause a pressure spike in the right head space 36R, potentially resulting in rapid combustion.

[0015] In this hydrogen engine 10, the provision of the head communication passage 42 suppresses a sudden increase in pressure in the head space 36. As in the case described above, when hydrogen burns in the left head space 36L, the pressure and flame caused by the combustion propagate through the engine body communication passage 38 to the crank chamber 22, and also propagate to the right head space 36R through the head communication passage 42. The pressure and flame reach the right head space 36R before the second pressure increase caused by combustion in the crank chamber 22, slowing down combustion in the right head space 36R and suppressing a sudden increase in pressure.

[0016] 2 is a diagram showing pressure changes in the head space 36 on the opposite side to the head space 36 where combustion first occurred. The dashed line B shows pressure changes when the inter-head communicating passage 42 is not provided, and the solid line A shows pressure changes when the inter-head communicating passage 42 is provided. As shown in the diagram, providing the inter-head communicating passage 42 can suppress a pressure increase in the head space 36 on the opposite side.

[0017] The bank angle of a V-type engine may be an angle other than 60°, such as 90°, 120°, or 180°. The present invention can also be applied to horizontally opposed engines and engines having three or more banks, such as so-called W-type engines. When there are three or more banks, each head space may be provided with an inter-head communication passage to one of the other head spaces. [Explanation of symbols]

[0018] 10 hydrogen engine, 12 bank, 14 cylinder, 16 cylinder block, 22 crankcase, 24 piston, 26 cylinder head, 28 combustion chamber, 34 head cover, 36 head space, 38 engine body internal communication passage, 40 head-to-head communication pipe, 42 head-to-head communication passage.

Claims

[Claim 1] In a hydrogen engine having multiple banks, a head cover that covers a valve mechanism disposed above the cylinders belonging to each bank and defines a head space therein; a communication passage in the engine body that communicates each of the head spaces with the crank chamber; an inter-head communication passage that communicates one of the head spaces with another of the head spaces; A hydrogen engine having:

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