Hydrogen engine

Abstract

This invention provides a hydrogen engine that suppresses pressure rise in the headspace caused by the combustion of leaked hydrogen. The hydrogen engine (10) having multiple cylinder banks (12L, 12R) includes: a top cover (34L, 34R) that covers the valve mechanism disposed above the cylinders (14) belonging to each cylinder bank (12L, 12R) and defines a headspace (36L, 36R) inside; an internal communication channel (38) of the engine body that connects each headspace (36L, 36R) to the crankcase (22); and an inter-head communication channel (42) that connects two headspaces (36L, 36R) to each other.

Description

Technical Field

[0001] This utility model relates to a hydrogen engine that uses hydrogen as fuel. Background Technology

[0002] A hydrogen engine that uses hydrogen as fuel is known. Patent Document 1 below shows a hydrogen engine (4). In the hydrogen engine (4), a valve chamber (44) housing the valve mechanism is connected to a crankcase (41) via a connecting pipe (46) and a cam chamber (45). Lubricating oil that lubricates the valve mechanism returns to the crankcase (41) through the connecting pipe (46). Note that the symbols in parentheses above are those used in Patent Document 1 below and are not related to the symbols used in the description of the embodiments in this application.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-12999 Utility Model Content

[0006] The problem to be solved by the utility model

[0007] In a hydrogen engine, some of the hydrogen supplied to the combustion chamber leaks through the piston ring gaps into the crankcase. If the hydrogen burns in the crankcase, the pressure reaches the top space of the valve train, where any unburned hydrogen also burns. In engines with multiple cylinder banks, such as V-type engines, the pressure rise caused by combustion in the top space of one cylinder bank flows back into the crankcase, where further combustion occurs, while the pressure rises further in the top space of the other cylinder bank. Therefore, combustion in the top space of the other cylinder bank can potentially become more intense.

[0008] The purpose of this invention is to mitigate the impact of pressure rise in the top space of one cylinder group on pressure rise in the top space of the other cylinder group.

[0009] Methods for solving problems

[0010] The hydrogen engine involved in this utility model has multiple cylinder groups and includes: a top cover that covers the valve mechanism arranged above the cylinders belonging to each cylinder group and defines a top space inside; an internal connecting channel of the engine body that connects each top space to the crankcase; and an inter-top connecting channel that connects one top space to other top spaces.

[0011] Utility Model Effect

[0012] By transmitting the combustion pressure generated in the top space of one party to the top space of the other party through the inter-top space connecting channel, the generation of a sharp pressure rise in the top space of the other party caused by combustion in the crankcase due to combustion in the top space of one party is suppressed. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the general structure of the hydrogen engine involved in this utility model.

[0014] Figure 2 A diagram showing the pressure changes within the top space. Detailed Implementation

[0015] The embodiments of this utility model will now be described with reference to the accompanying drawings. Figure 1 This diagram schematically illustrates a cross-section of a V-type hydrogen engine 10. The basic structure of the hydrogen engine 10 is the same as that of existing engines such as gasoline engines. The hydrogen engine 10 is a so-called V-type engine with two cylinder banks 12. When it is necessary to distinguish between the two cylinder banks, the cylinder bank on the left side of the diagram is referred to as the left cylinder bank 12L, and the cylinder bank on the right side is referred to as the right cylinder bank 12R. Furthermore, for the elements belonging to each cylinder bank 12L and 12R, the element symbols are similarly prefixed with L and R to distinguish between left and right.

[0016] The hydrogen engine 10 has a cylinder block 16 that defines a V-shape for cylinders 14 with a 60° bank angle, and an oil pan 18 that is configured to cover an opening at the bottom of the cylinder block 16. A crankcase 22 for housing a crankshaft 20 is defined by the cylinder block 16 and the oil pan 18. A piston 24 reciprocates within the cylinder 14 along its axial direction. The piston 24 and the crankshaft 20 are connected by a connecting rod. For simplicity, in... Figure 1 The detailed structure of the crankshaft 20 and the connecting rod are omitted. Through the connecting rod and the crankshaft 20, the reciprocating motion of the piston 24 is converted into the rotational motion of the crankshaft 20.

[0017] The cylinder head 26 is attached to the cylinder block 16 to cover the open end of the cylinder 14 opposite to the crankcase 22. The cylinder 14, piston 24, and cylinder head 26 define a combustion chamber 28 enclosed by them. An intake port 30 for introducing the air-fuel mixture into the combustion chamber 28 and an exhaust port 32 for discharging the exhaust gases are formed on the cylinder head 26. An intake valve (not shown) and an exhaust valve (not shown) are respectively disposed at the combustion chamber 28-side ends of the intake port 30 and exhaust port 32, opening and closing the respective ports at predetermined timings. On the side of the cylinder head 26 opposite to the combustion chamber 28, a valve mechanism (not shown) is provided for actuating the intake and exhaust valves. The valve mechanism may include, for example, a camshaft with a cam, a rocker arm that transmits the motion of the cam to the valve, and a valve spring that applies force to the valve to a closed position.

[0018] On the side of the cylinder head 26 opposite to the combustion chamber 28, a top cover 34 is disposed to cover the valve mechanism. The top cover 34 cooperates with the cylinder head 26 to define a top space 36 internally. An engine block internal communication channel 38 is formed on the cylinder head 26 and the cylinder block 16, connecting the top space 36 and the crankcase 22. Lubricating oil that lubricates the valve mechanism in the top space 36 returns to the crankcase 22 through the engine block internal communication channel 38.

[0019] The hydrogen engine 10 has an inter-top communication pipe 40 that connects to the left and right top covers 34L and 34R at both ends. The inter-top communication pipe 40 defines an inter-top communication channel 42 that connects the left and right top spaces 36L and 36R.

[0020] When the hydrogen engine 10 is running, hydrogen, as fuel, leaks from the gap between the cylinder 14 and piston 24, particularly from the gap between the piston rings, into the crankcase 22. The hydrogen in the crankcase 22 also accumulates in the headspace 36 through the engine body internal communication channel 38. When the hydrogen is ignited and burned in the crankcase 22, the pressure in the crankcase 22 rises, and this pressure is transmitted through the engine body internal communication channel 38, compressing the gas containing the hydrogen in the headspace 36. Furthermore, the gas in the crankcase 22 is sent to the headspace 36 through the engine body internal communication channel 38, further increasing the pressure in the headspace 36. As a result, if the hydrogen burns in either side, for example, the left headspace 36L, the pressure generated by the combustion flows back to the crankcase 22 through the engine body internal communication channel 38L. If the hydrogen is burned again in the crankcase 22 due to this pressure increase, the pressure on the opposite side (the right headspace 36R) rises in the same manner as on the left side. The initial combustion within the crankcase 22 and the second combustion within the crankcase 22 caused by combustion in the left top space 36L will cause a rapid increase in pressure in the right top space 36R, potentially resulting in a rapid combustion.

[0021] In this hydrogen engine 10, a sharp pressure rise in the top space 36 is suppressed by providing the top inter-connection channel 42. Similarly, when hydrogen burns in the left top space 36L, the pressure generated by combustion and the flame spread through the engine body internal connection channel 38 to the crankcase 22, and also through the top inter-connection channel 42 to the right top space 36R. Before the pressure rise caused by the second combustion in the crankcase 22, the pressure and flame reach the right top space 36R, thus slowing down combustion in the right top space 36R and suppressing a sharp pressure rise.

[0022] Figure 2 This diagram illustrates the pressure changes in the top space 36 opposite to the top space 36 where combustion initially occurs. Dashed line B represents the pressure change without the top inter-combustion channel 42, and solid line A represents the pressure change with the top inter-combustion channel 42 present. As shown, by providing the top inter-combustion channel 42, the pressure rise in the opposite top space 36 can be suppressed.

[0023] The cylinder angle of a V-type engine can also be an angle other than 60°, such as 90°, 120°, 180°, etc. Furthermore, this invention can also be applied to horizontally opposed engines, and further to engines with three or more cylinder banks, such as so-called W-type engines. In the case of three or more cylinder banks, a connecting passage between the top spaces can be provided for one of the other top spaces.

[0024] Symbol Explanation

[0025] 10… Hydrogen engine; 12… Cylinder assembly; 14… Cylinder; 16… Cylinder block; 22… Crankcase; 24… Piston; 26… Cylinder head; 28… Combustion chamber; 34… Top cover; 36… Top space; 38… Internal connecting passage of engine body; 40… Top connecting pipe; 42… Top connecting passage.

Claims

1. A hydrogen engine having a plurality of cylinder groups, characterized by, Having: a top cover which covers a valve mechanism arranged above a cylinder belonging to each of the cylinder groups and defines a top space inside; an engine main body internal communication passage which communicates each of the top spaces and a crankcase; a top intercommunication passage which communicates one of the top spaces and the other of the top spaces.

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