Gas engine

Abstract

The invention provides a gas engine capable of combusting hydrogen. Comprises: a cylinder liner (14); a cylinder head (15); a gas injection valve (5) for injecting hydrogen gas; gas supply passages (32, 33) for supplying hydrogen gas to the gas injection valves; a block (7) which is fixed to the upper surface (15a) of the cylinder head, into which the gas injection valve is inserted, and which is formed separately from the cylinder head; and sealing members (62, 63) for sealing a gap between the gas supply passage and the gas injection valve. The gas supply passage has a first gas supply passage (32) defined and formed inside the cylinder head, and a second gas supply passage (33) defined and formed inside the block and connecting the first gas supply passage and the gas injection valve, and the seal member is provided at a connection portion (S1) where the second gas supply passage and the gas injection valve are connected. Therefore, heat damage to the seal member can be suppressed while the gas supply passage is provided in the cylinder head.

Description

Technical Field

[0001] The present disclosure relates to a gas engine. Background Art

[0002] Patent Document 1 discloses, as an example of a so-called gas engine, an engine (a large low-speed turbo two-stroke diesel engine) configured to supply gaseous fuel (gas fuel) into a combustion chamber. Specifically, the engine includes: a gas fuel valve inserted into a cylinder head (an upper cover of a cylinder), and a gas supply passage (supply conduit) formed in the cylinder head and supplying gas fuel to the gas fuel valve.

[0003] Patent Document 1: Japanese Patent Publication No. 2015-86867 Summary of the invention

[0004] 1. Technical problem to be solved by the invention

[0005] In order to suppress leakage of gas fuel from a gas engine, the inventors of the present application have developed the following technical solution: by providing various flow paths for gas fuel to flow in a cylinder head, the various flow paths are integrated to reduce the number of connection points between the flow paths.

[0006] As a specific example, a technical solution can be considered in which a gas fuel valve is inserted into a cylinder head and a gas supply passage is provided in the cylinder head as disclosed in the above-mentioned Patent Document 1. However, when such a structure is adopted, there is still a concern that gas may leak from the connection portion where the gas supply passage and the gas fuel valve are connected.

[0007] In order to eliminate such concerns, a sealing member such as an O-ring has to be provided in the cylinder head to seal the gap between the gas supply passage and the gas fuel valve.

[0008] However, when the sealing member is disposed in the cylinder head, the sealing member may be damaged by the heat generated by the combustion of the gas fuel, which is disadvantageous in extending the life of the gas engine.

[0009] The technology disclosed in this specification is made to solve the above-mentioned technical problems, and its purpose is to suppress thermal damage to sealing components while providing a gas supply passage in a cylinder head in a gas engine.

[0010] 1. Technical solutions for solving technical problems 1

[0011] The first aspect of the present disclosure relates to a gas engine capable of burning gas fuel in a cylinder. The gas engine includes a cylinder liner, a cylinder head, a gas injection valve, a gas supply passage, a block, and a sealing component. The cylinder liner allows a piston to reciprocate. The cylinder head is fixed to the upper end of the cylinder liner. As a cover of the cylinder, the gas injection valve is provided with an injection port for injecting the gas fuel into the cylinder. The gas supply passage supplies the gas fuel to the gas injection valve. The block is fixed to the upper surface of the cylinder head. The gas injection valve is inserted into the block. The block and the cylinder head are separately formed. The sealing component seals the gap between the gas supply passage and the gas injection valve. The gas supply passage includes a first gas supply passage and a second gas supply passage. The first gas supply passage is divided and formed inside the cylinder head. The second gas supply passage is divided and formed inside the block. The first gas supply passage is connected to the gas injection valve. The sealing component is provided at a connection portion where the second gas supply passage is connected to the gas injection valve.

[0012] According to the first aspect, the gas injection valve is not directly connected to the first gas supply passage defined and formed in the cylinder head, but is indirectly connected via the block body formed separately from the cylinder head.

[0013] By connecting in this way, even if a sealing member is not provided in the cylinder head, a sealing member can be provided at the connection portion between the block and the gas injection valve (the connection portion between the second gas supply passage and the gas injection valve).

[0014] Here, since the block is arranged on the upper surface of the cylinder head, the sealing member can be kept away from the combustion chamber compared to a structure in which the sealing member is arranged in the cylinder head. Therefore, thermal damage to the sealing member can be suppressed by keeping the sealing member away from the combustion chamber.

[0015] As described above, according to the first aspect, the gas supply passage can be provided in the cylinder head while suppressing thermal damage to the sealing member.

[0016] In addition, the second aspect of the present disclosure may also be configured as follows: the gas engine further includes a gas introduction passage and a socket, the gas introduction passage opens on the outer peripheral surface of the gas injection valve to connect the second gas supply passage with the injection port, the socket is provided on the block for the gas injection valve to be inserted, in the axial direction of the gas injection valve, if the injection port side in the axial direction is regarded as the top end side, and the opposite side of the injection port in the axial direction is regarded as the base end side, the outer peripheral surface of the gas injection valve has a first outer peripheral surface, a second outer peripheral surface and a third outer peripheral surface, the first outer peripheral surface extends along the axial direction, the second outer peripheral surface is arranged at a position closer to the base end side than the first outer peripheral surface, the diameter of the second outer peripheral surface is larger than the diameter of the first outer peripheral surface, and the second outer peripheral surface extends along the axial direction, the third outer peripheral surface is composed of a step or an inclined surface connecting the first outer peripheral surface and the second outer peripheral surface, The inner circumference of the insertion hole includes a first inner circumference, a second inner circumference, and a third inner circumference, the first inner circumference is in contact with the first outer circumference, the second inner circumference is arranged at a position closer to the base end than the first inner circumference, the diameter of the second inner circumference is larger than the diameter of the first inner circumference, and the second inner circumference is in contact with the second outer circumference, the third inner circumference is composed of a step or an inclined surface connecting the first inner circumference and the second inner circumference, and in a state where the gas injection valve is fastened to the block, the third outer circumference and the third inner circumference are opposed to each other with a gap in the axial direction or in a radial direction orthogonal to the axial direction, the gap defines a first space for the gas fuel to flow in a circumferential direction around the central axis of the gas injection valve, the gas introduction passage is opened in a manner connected to the first space, and the sealing component is installed at least on the first outer circumference to suppress leakage of gas through the first space.

[0017] Assume that the following structure is adopted: the third outer peripheral surface and the third inner peripheral surface are not provided, the diameter of the first outer peripheral surface is equal to the diameter of the second outer peripheral surface, and the diameter of the first inner peripheral surface is equal to the diameter of the second inner peripheral surface. If such a structure is adopted, when the gas injection valve is inserted into the block, the sealing component installed on the first outer peripheral surface of the gas injection valve will rub against both the second inner peripheral surface and the first inner peripheral surface. In this case, there is a concern that the sealing component may be damaged due to wear.

[0018] In contrast, according to the second aspect, the second inner peripheral surface is configured such that its diameter is larger than the diameter of the first inner peripheral surface. Therefore, when the gas injection valve is inserted into the block, it is possible to prevent the sealing component mounted on the first outer peripheral surface of the gas injection valve from contacting the second inner peripheral surface. Thus, it is possible to prevent the sealing component from being damaged by the contact. In addition, by making the diameter of the second outer peripheral surface larger while making the diameter of the second inner peripheral surface larger than the diameter of the first outer peripheral surface, it is possible to maintain contact between the inner peripheral surface of the jack and the outer peripheral surface of the gas injection valve. This helps to prevent leakage of gas fuel.

[0019] In addition, by using the third outer peripheral surface and the third inner peripheral surface to divide and form the first space, even if a groove is not newly provided on the outer peripheral surface of the gas injection valve, a gas storage portion for gas fuel to flow in the circumferential direction can be formed. Usually, grooving is required to make such a groove, but this aspect does not require such processing, so no special tool for grooving is required. As a result, the ease of processing of the block can be improved.

[0020] That is, the third outer peripheral surface and the third inner peripheral surface involved in the second aspect can simultaneously take into account the following aspects: suppressing the leakage of hydrogen, suppressing the damage to the sealing component, allowing the hydrogen to flow in the circumferential direction, and improving the machinability of the block.

[0021] In addition, a third aspect of the present disclosure may also be configured as follows: the gas engine further includes a second space and a third space, the second space being divided and formed between the first outer peripheral surface and the first inner peripheral surface, being located closer to the top end side than the first space, and for the gas fuel leaked from the first space to flow in, the third space being divided and formed between the second outer peripheral surface and the second inner peripheral surface, being located closer to the base end side than the first space, and for the gas fuel leaked from the first space to flow in, the sealing component being composed of a first sealing component, a second sealing component, a third sealing component, and a fourth sealing component in sequence from the top end side toward the base end side, the first sealing component being located on the top end side relative to the second space, and being The sealing member is installed on the first outer peripheral surface in a manner of being sandwiched between the first outer peripheral surface and the first inner peripheral surface, the second sealing member is located on the base end side relative to the second space and is installed on the first outer peripheral surface in a manner of being sandwiched between the first outer peripheral surface and the first inner peripheral surface, the third sealing member is located on the top end side relative to the third space and is installed on the second outer peripheral surface in a manner of being sandwiched between the second outer peripheral surface and the second inner peripheral surface, the fourth sealing member is located on the base end side relative to the third space and is installed on the second outer peripheral surface in a manner of being sandwiched between the second outer peripheral surface and the second inner peripheral surface, and the upstream end of the gas introduction passage is arranged between the second sealing member and the third sealing member in the axial direction.

[0022] According to the third aspect, the second sealing member and the third sealing member are arranged on both sides of the first space in the valve axis direction, and the first sealing member and the fourth sealing member are arranged on both sides slightly farther away. With such an arrangement, a double sealing structure can be realized in which four sealing members are used to seal the first space.

[0023] In addition, by defining a second space between the first sealing member and the second sealing member and defining a third space between the third sealing member and the fourth sealing member, not only a double sealing structure for the first space can be realized, but also a sealing structure for sealing the second space and the third space can be realized simultaneously.

[0024] In addition, the fourth aspect of the present disclosure may also be configured as follows: the first sealing component and the second sealing component are installed in a recessed portion provided on the first outer peripheral surface, the third sealing component and the fourth sealing component are installed in a recessed portion provided on the second outer peripheral surface, the second space is formed by a groove provided on the first inner peripheral surface and the first outer peripheral surface opposite to the groove, and the third space is formed by a groove provided on the second inner peripheral surface and the second outer peripheral surface opposite to the groove.

[0025] Assume that the following structure is configured: the third outer peripheral surface and the third inner peripheral surface are not provided, the diameter of the first outer peripheral surface is equal to the diameter of the second outer peripheral surface, and the diameter of the first inner peripheral surface is equal to the diameter of the second inner peripheral surface. If this structure is adopted, when the gas injection valve is inserted into the block, the sealing component installed on the first outer peripheral surface of the gas injection valve will rub against both the second inner peripheral surface and the first inner peripheral surface. In this case, when the sealing component rubs against the second inner peripheral surface, there is a particular concern about the friction between the sealing component and the groove provided on the second inner peripheral surface.

[0026] In contrast, according to the fourth aspect, when the gas injection valve is inserted into the block, the sealing member mounted on the first outer peripheral surface of the gas injection valve can be prevented from contacting the second inner peripheral surface or the groove provided on the second inner peripheral surface, which is advantageous in preventing damage to the sealing member due to the contact.

[0027] In addition, the fifth aspect of the present disclosure may be configured such that: the gas fuel is hydrogen, and an upstream end portion of the gas introduction passage opens perpendicularly to the first outer peripheral surface.

[0028] According to the fifth aspect, the opening area can be reduced as much as possible compared to, for example, the case where the upstream end is opened obliquely. Reducing the opening area is effective in shortening the interval between the second sealing member and the third sealing member in the axial direction. Shortening the interval helps to reduce the volume of the first space. Furthermore, reducing the volume of the first space is advantageous in reducing the amount of hydrogen that can be accumulated in the space and further improving safety. As such, the structure of the gas injection valve involved in the fifth aspect is very suitable for the case where hydrogen is used as the gas fuel.

[0029] In addition, the sixth aspect of the present disclosure may also be configured such that: the upstream end of the gas introduction passage opens at a boundary between the first outer peripheral surface and the third outer peripheral surface.

[0030] According to the sixth aspect, by making the upstream end portion open at the boundary portion, the interval between the second sealing member and the third sealing member in the axial direction can be shortened compared to a structure in which the upstream end portion opens at the top end portion of the first outer peripheral surface. As a result, the volume of the first space can be reduced, and the amount of hydrogen that can be accumulated in the space can be reduced. This is very advantageous in further improving safety.

[0031] In addition, the seventh aspect of the present disclosure can also be constructed as follows: the gas fuel is hydrogen, the block is made of solid steel, the block has a lower surface and a socket, the lower surface is mounted on the upper surface of the cylinder head, the socket is for the gas injection valve to be inserted, the second gas supply passage has an upstream end and a downstream end, the upstream end is open on the lower surface, the downstream end is open on the inner circumferential surface of the socket, the upstream end is arranged at a position closer to the outside than the downstream end in a radial direction orthogonal to the axial direction of the gas injection valve, the second gas supply passage also has a first part and a second part, the first part extends upward from the upstream end, the second part follows the first part, and extends to the downstream end in a manner that is inclined toward the inner side of the radial direction as it goes upward in the height direction.

[0032] When solid steel is used, it is usually considered to process the second gas supply passage by combining a through hole extending in the axial direction and a through hole extending in the radial direction. However, when such through holes are provided in two directions, so-called dead holes are generated, and it is necessary to plug the dead holes with a sealing plug or the like. However, the use of a sealing plug is not appropriate because it may cause hydrogen leakage and hydrogen embrittlement due to the accumulation of hydrogen in the closed portion formed by the sealing plug.

[0033] In contrast, the second gas supply passage according to the seventh aspect has a second portion extending obliquely, thereby making it possible to construct the second gas supply passage without using a dead hole or even a sealing plug, which helps to suppress hydrogen leakage and hydrogen embrittlement.

[0034] In addition, the eighth aspect of the present disclosure may also be configured as follows: a dimension of the second portion in a flow direction of the gas fuel is longer than a dimension of the first portion in the flow direction.

[0035] According to the eighth aspect, by making the second portion relatively longer than the first portion, the second gas supply passage can be extended obliquely for a longer time. By making the second gas supply passage be extended obliquely for a longer time, the hydrogen gas can be smoothly guided to the downstream end of the second gas supply passage and further to the gas injection valve without the hydrogen gas staying in the middle of the second gas supply passage.

[0036] Effect of the invention

[0037] As described above, according to the present disclosure, in a gas engine, it is possible to suppress thermal damage to a sealing member while providing a gas supply passage in a cylinder head. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a side view showing the overall structure of the gas engine;

[0039] Figure 2 is a schematic diagram showing the structure of a gas engine;

[0040] Figure 3 is a cross-sectional view schematically showing an upper structure of a gas engine;

[0041] Figure 4 is a perspective view showing the surrounding structure of the cylinder head;

[0042] Figure 5 is a top view showing the surrounding structure of the cylinder head;

[0043] Figure 6 is a front view showing the surrounding structure of the cylinder head;

[0044] Figure 7 yes Figure 5 AA section view;

[0045] Figure 8 is a longitudinal sectional view showing the structure of the gas injection valve;

[0046] Fig. 9 Yes Figure 7 The enclosed portion XI is enlarged and shown in FIG;

[0047] Fig.10 is a perspective view showing the structure of the block;

[0048] Fig.11 is a longitudinal sectional view showing the structure of the block;

[0049] Fig.12 yes Figure 7 BB cross-sectional view.

[0050] 1. Symbol Description 1

[0051] 1-engine (gas engine); 14-cylinder liner; 15-cylinder head; 15a-upper surface of cylinder head; 16-cylinder; 21-piston; 3-gas supply system; 32-first gas supply passage (gas supply passage); 33-second gas supply passage (gas supply passage); 33a-upstream end; 33b-downstream end; 34-gas gate valve; 5-gas injection valve; 5A-first gas injection valve; 5B-second gas injection valve; 5a-injection port; 50- Cylindrical body; 50a-first concave portion (a concave portion provided on the first outer peripheral surface); 50b-second concave portion (a concave portion provided on the first outer peripheral surface); 50c-third concave portion (a concave portion provided on the second outer peripheral surface); 50d-fourth concave portion (a concave portion provided on the second outer peripheral surface); 51-first main body; 52-second main body; 52a-first outer peripheral surface; 52b-second outer peripheral surface; 52c-third outer peripheral surface; 53-third main body; 57-first internal flow path (gas introduction passage); 57a-upstream passage (upstream end of gas introduction passage); 61-first sealing member (sealing member); 62-second sealing member (sealing member); 63-third sealing member (sealing member); 64-fourth sealing member (sealing member); 7-block; 7A-first block; 7B-second block; 70-rectangular body; 70u-lower surface; 72-first fastening hole; 73-second fastening hole; 74-insertion hole; 74a-first inner peripheral surface; 74b-first Two inner peripheral surfaces; 74c-the third inner peripheral surface; 75-the first part; 76-the second part; 77-the first groove part (the groove provided on the first inner peripheral surface); 78-the second groove part (the groove provided on the second inner peripheral surface); L1-the size of the first part; L2-the size of the second part; Op-the center axis of the piston; Ov-the center axis of the gas injection valve; S1-the first space (the connecting part and the gap between the second gas supply passage and the gas injection valve); S2-the second space; S3-the third space. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present disclosure will be described based on the accompanying drawings. It should be noted that the following description is only for example. Figure 1 is a side view showing the overall structure of a gas engine (hereinafter, also simply referred to as an "engine") 1, Figure 2 is a schematic diagram showing the structure of the engine 1, Figure 3 It is a cross-sectional view schematically showing the upper structure of the engine 1 .

[0053] <Overall structure>

[0054] The engine 1 is a gas engine capable of burning a gas fuel in its cylinder 16. In particular, in the present embodiment, the gas fuel is hydrogen. It should be noted that the gas fuel is not limited to hydrogen. Other gas fuels such as methane gas may also be used. In addition, the engine 1 may be an engine that burns the gas fuel alone, or an engine that uses the gas fuel together with other oil fuels (for example, hydrogen and heavy oil are mixed and burned).

[0055] The engine 1 is a two-stroke cycle engine of a direct current scavenging type, and is mounted on large ships such as tankers, container ships, and car carriers. The engine 1 is used as a main engine for propelling the ship equipped with the engine 1. The output shaft of the engine 1 is connected to the propeller (not shown) of the ship via a propeller shaft (not shown). When the engine 1 is running, the output of the engine 1 is transmitted to the propeller, thereby propelling the ship.

[0056] <Main structure of the engine>

[0057] like Figure 1 to Figure 3 As shown, the engine 1 includes an engine body 10 having the above-mentioned cylinders 16, and a gas supply system 3. Each cylinder 16 defines a combustion chamber 17 for burning gas fuel.

[0058] like Figure 1 As shown, a plurality of cylinders 16 (six in this embodiment) are arranged in a predetermined direction. Hereinafter, the arrangement direction of the cylinders 16 is set as the front-to-back direction or the first direction, and the front-to-back direction and the first direction are set as the first direction. Figure 3 The direction orthogonal to the piston axis (the central axis of the piston 21 inserted into each cylinder 16) 0p shown in the figure is set as the left-right direction or the second direction.

[0059] (1) Engine body 10

[0060] As described above, the engine body 10 has a plurality of cylinders 16. The engine body 10 is a two-stroke engine and is installed in an engine room of a ship. It should be noted that the following description is common to the six cylinders 16 except for the contents specifically described.

[0061] like Figure 2 As shown, the engine body 10 involved in this embodiment is configured as a so-called crosshead internal combustion engine in order to achieve its long stroke. That is, in the engine body 10, a piston rod 22 supporting a piston 21 from below and a connecting rod 24 connected to a crankshaft 23 are connected through a crosshead 25.

[0062] Specifically, the engine body 10 includes: a base 11 located below, a frame 12 provided on the base 11, a cylinder jacket 13 provided on the frame 12, a cylinder liner 14, and a cylinder head 15. Each cylinder 16 is provided in the cylinder jacket 13. The engine body 10 also includes: a piston 21 disposed in the cylinder 16 and reciprocating in the cylinder 16, and an output shaft (e.g., a crankshaft 23) that rotates in conjunction with the reciprocating motion.

[0063] Here, the engine base 11 constitutes a crankcase of the engine 1, and a crankshaft 23 and a bearing 26 for rotatably supporting the crankshaft 23 are housed in the engine base 11. The crankshaft 23 is connected to the lower end of a connecting rod 24 via a crank 27.

[0064] The crosshead 25 is arranged between a pair of guide plates 28 and slides in the up-down direction along each guide plate 28. That is, the pair of guide plates 28 guide the crosshead 25 to slide. The crosshead 25 is connected to the piston rod 22 and the connecting rod 24 via a crosshead pin 29. The crosshead pin 29 is connected to the piston rod 22 so as to move up and down as a whole, and on the other hand, the crosshead pin 29 is connected to the connecting rod 24 so as to swing the connecting rod 24 with the upper end of the connecting rod 24 as a fulcrum.

[0065] The cylinder water jacket 13 supports the cylinder liner 14, which is configured as an inner cylinder and allows the piston 21 to reciprocate. Specifically, the piston 21 is arranged inside the cylinder liner 14. The cylinder liner 14 allows the piston 21 to reciprocate in the up-and-down direction along the inner wall of the cylinder liner 14. The upper end of the cylinder liner 14 is open.

[0066] In addition, a cylinder head 15 is fixed to the upper end of the cylinder liner 14. The cylinder head 15 and the cylinder liner 14 together constitute the cylinder 16. The cylinder head 15 serves as a cover of the cylinder 16 by closing the upper end of the cylinder liner 14.

[0067] In addition, an exhaust valve 18 is provided on the cylinder head 15, and the exhaust valve 18 is driven by a valve gear (not shown). The exhaust valve 18, the cylinder 16 formed by the cylinder liner 14 and the cylinder head 15, and the top surface of the piston 21 define a combustion chamber 17. The exhaust valve 18 connects and disconnects the combustion chamber 17 with an exhaust pipe 19. The exhaust pipe 19 has an exhaust port connected to the combustion chamber 17, and the exhaust valve 18 is configured to open and close the exhaust port.

[0068] In addition, if Figure 2 and Figure 3 As shown, one or more gas injection valves 5 for supplying hydrogen to the combustion chamber 17 are provided on the cylinder head 15. The gas injection valve 5 is provided with an injection port 5a for injecting hydrogen into the cylinder 16.

[0069] In the present embodiment, two gas injection valves 5 are provided for each cylinder 16, and the gas injection valves 5 are provided in a posture facing the interior of the combustion chamber 17. Each gas injection valve 5 has an injection port 5a at its top end, and is configured to inject hydrogen gas from the injection port 5a. Hereinafter, one of the two gas injection valves 5 is sometimes referred to as a "first gas injection valve 5A", and the other is sometimes referred to as a "second gas injection valve 5B".

[0070] In addition, if Figure 3 As shown, one or more blocks 7 that are separate from the cylinder head 15 are fixed to the upper surface of the cylinder head 15. Figures 4 to 6 As shown, the number of blocks 7 involved in this embodiment is the same as that of the gas injection valves 5 (that is, two in this embodiment), and corresponding gas injection valves 5 are respectively inserted into the blocks 7. Hereinafter, one of the two blocks 7 into which the first gas injection valve 5A is inserted is sometimes referred to as the "first block 7A", and the other of the two blocks 7 into which the second gas injection valve 5B is inserted is sometimes referred to as the "second block 7B".

[0071] like Figure 3 As shown, each gas injection valve 5 is connected to the gas supply system 3. Hydrogen gas is supplied from the gas supply system 3 to each gas injection valve 5 through a first gas supply passage 32 and a second gas supply passage 33 described later. When each gas injection valve 5 is opened in a state where hydrogen gas is supplied, hydrogen gas is supplied into the combustion chamber 17.

[0072] Each gas injection valve 5 supplies hydrogen to the combustion chamber 17, causing the hydrogen to burn in the combustion chamber 17. The piston 21 reciprocates in the vertical direction due to the combustion. At this time, when the exhaust valve 18 operates and the combustion chamber 17 is opened, the exhaust gas generated by the combustion is squeezed out to the exhaust pipe 19, and the gas is introduced into the combustion chamber 17 from the scavenging port (not shown).

[0073] Furthermore, when the piston 21 reciprocates due to combustion, the piston rod 22 reciprocates in the vertical direction together with the piston 21. As a result, the crosshead 25 connected to the piston rod 22 reciprocates in the vertical direction. The crosshead 25 is configured to allow the connecting rod 24 to swing, so that the connecting rod 24 swings with the connection portion where the connecting rod 24 and the crosshead 25 are connected as a fulcrum. In addition, the crank 27 connected to the lower end of the connecting rod 24 performs a crank motion, and the crankshaft 23 rotates with the crank motion. In this way, the crankshaft 23 converts the reciprocating motion of the piston 21 into a rotational motion, so that the propeller of the ship rotates together with the propeller shaft. As a result, the ship is pushed forward.

[0074] (2) Gas supply system 3

[0075] like Figure 3As shown, the gas supply system 3 includes a gas supply module 31, gas supply passages 32, 33, a gas gate valve (GGV) 34, and a gas pipe 39. In addition, the engine 1 according to the present embodiment further includes sealing members 62, 63 as components related to hydrogen supply.

[0076] The gas supply module 31 includes a hydrogen storage tank 31 a and a gas valve train (GVT) 31 b .

[0077] The hydrogen tank 31a stores hydrogen gas. The hydrogen gas stored in the hydrogen tank 31a is adjusted to an appropriate temperature by a temperature adjustment mechanism (not shown) by operating a pump (not shown) and then supplied to the GVT 31b.

[0078] The GVT 31b has various pipes (not shown) and electromagnetic valves (not shown) for opening and closing the pipes. The electromagnetic valves of the GVT 31b are electrically connected to the controller 100 and operate according to the control signal input from the controller 100. The GVT 31b is connected to the gas supply passages 32 and 33 via the gas pipe 39. By opening and closing the electromagnetic valves by the GVT 31b, the supply of hydrogen gas to the gas supply passages 32 and 33 and then to the gas injection valves 5 is controlled.

[0079] The gas supply passages 32 and 33 are connected to the gas injection valve 5 to supply hydrogen to the gas injection valve 5. The sealing members 62 and 63 seal the gap between the gas supply passages 32 and 33 and the gas injection valve 5. It should be noted that the gap sealed by the sealing members 62 and 63 is the gap between the inner peripheral surface of the insertion hole 74 and the outer peripheral surface of the gas injection valve.

[0080] In more detail, the gas supply passages 32 and 33 are respectively a first gas supply passage 32 and a second gas supply passage 33. The first gas supply passage 32 is divided and formed inside the cylinder head 15, and the second gas supply passage 33 is divided and formed inside the block 7, and connects the first gas supply passage 32 with the gas injection valve 5.

[0081] The first gas supply passage 32 connects the downstream end of the gas pipe 39 and the upstream end of the second gas supply passage 33. A gas gate valve 34 is arranged in the middle of the first gas supply passage 32 to open and close the first gas supply passage 32. The gas gate valve 34 is configured to block the flow of hydrogen in the first gas supply passage 32 by operating according to the oil pressure of the working oil.

[0082] The second gas supply passage 33 connects the downstream end of the first gas supply passage 32 to the first internal flow passage 57 as a gas introduction passage. As described later, the second gas supply passage 33 is composed of a flow passage connected to the first gas injection valve 5A and a flow passage connected to the second gas injection valve 5B. In order to connect to these flow passages, the first gas supply passage 32 is branched into two flow passages in the middle (see Figure 5 Symbols 32a, 32b).

[0083] <Cylinder head peripheral structure>

[0084] Furthermore, in the engine 1 according to the present embodiment, Figure 3 As shown, the sealing components 62 and 63 are arranged at the connection portion between the second gas supply passage 33 and the gas injection valve 5 (in other words, at the connection portion between the block 7 and the gas injection valve 5), and are not arranged between the cylinder head 15 and the gas injection valve 5.

[0085] The cylinder head 15, the gas injection valve 5 and the block 7 according to the present embodiment are described in detail below. It should be noted that the following description is common to each of the plurality of cylinders 16, and the first gas injection valve 5A and the second gas injection valve 5B, except for the contents specifically described.

[0086] (1) Specific structure of cylinder head 15

[0087] Figure 4 is a perspective view showing the surrounding structure of the cylinder head 15, Figure 5 is a top view showing the surrounding structure of the cylinder head 15, Figure 6 It is a front view showing the surrounding structure of the cylinder head 15.

[0088] like Figures 4 to 6 As shown in the figure, the cylinder head 15 is formed of a thick plate-shaped metal block having an upper surface 15a which is flat in the front-rear direction and the left-right direction. The cylinder head 15 has a plurality of (six in the example) head fastening holes 15b and a plurality of (three in the example) exhaust valve fastening holes 15c. The plurality of head fastening holes 15b and the exhaust valve fastening holes 15c are both open in the upper surface 15a.

[0089] In addition, a through hole 15d is formed in the center portion of the cylinder head 15 so as to be coaxial with the center axis Op of the piston 21. The through hole 15d has a circular cross section and penetrates the cylinder head 15 in the thickness direction.

[0090] Here, fasteners (e.g., bolts) for fastening the cylinder head 15 to the cylinder liner 14 are inserted into the plurality of head fastening holes 15b. The plurality of head fastening holes 15b are arranged at equal intervals in the circumferential direction around the central axis Op. Each head fastening hole 15b penetrates the cylinder head 15 in the thickness direction (vertical direction).

[0091] On the other hand, fasteners (e.g., bolts) for fastening the exhaust valve 18 to the cylinder head 15 are inserted into the plurality of exhaust valve fastening holes 15c. The plurality of exhaust valve fastening holes 15c are arranged at equal intervals in the circumferential direction. In the radial direction orthogonal to the central axis Op, each exhaust valve fastening hole 15c is arranged on the inner side (radially inner side) of each head fastening hole 15b and on the outer side (radially outer side) of the through hole 15d.

[0092] In addition, the cylinder head 15 has an asymmetric shape in the left-right direction. Specifically, the cylinder head 15 has a semicircular portion 151 protruding to one side (right side) in the left-right direction, and a flange portion 152 protruding to the other side (left side) in the left-right direction. The semicircular portion 151 has a right side surface that is curved in a semicircular shape. The central axis (center of the arc) of the semicircle of the right side surface roughly coincides with the piston axis Op.

[0093] On the other hand, the flange portion 152 protrudes outwardly of the plurality of cover fastening holes 15 b in the radial direction. The plurality of exhaust valve cover fastening holes 15 b and the plurality of exhaust valve fastening holes 15 c open in the semicircular portion 151 .

[0094] The gas gate valve 34 is configured to be inserted into the upper surface of the flange portion 152. Figure 5 As shown by the dotted line in the figure, the first gas supply passage 32 opened and closed by the gas gate valve 34 is divided and formed inside the flange portion 152 and the semicircular portion 151. The first gas supply passage 32 is divided into two flow passages 32a and 32b starting from the insertion portion of the gas gate valve 34 at the flange portion 152, and extends to the semicircular portion 151 respectively.

[0095] In addition, a first mounting surface 153A and a second mounting surface 153B are provided on the upper surface 15a of the cylinder head 15. The first block 7A supporting the first gas injection valve 5A is placed on the first mounting surface 153A, and the second block 7B supporting the second gas injection valve 5B is placed on the second mounting surface 153B.

[0096] like Figure 6 As shown, the first mounting surface 153A and the second mounting surface 153B extend in a manner that they are inclined downward as they are farther away from the piston axis Op in the radial direction. As shown in the figure, the first mounting surface 153A and the second mounting surface 153B are formed to be substantially line symmetrical with the piston axis Op as the symmetry axis.

[0097] In addition, if Figure 5As shown, the downstream end of one of the flow paths (flow path 32a) constituting the first gas supply path 32 opens at the bottom surface (inclined surface) of the first mounting surface 153A. Figure 6 As shown, an insertion hole 154 for inserting the tip of the first gas injection valve 5A is also opened in the bottom surface. The insertion hole 154 is a hole with a bottom and a circular cross section extending along the central axis (valve axis Ov described later) of the first gas injection valve 5A.

[0098] Similarly, the downstream end of the other flow path (flow path 32b) constituting the first gas supply passage 32 opens at the bottom surface (inclined surface) of the second mounting surface 153B. The insertion hole 154 for inserting the top end of the second gas injection valve 5B also opens at the bottom surface. The insertion hole 154 is a hole extending along the valve axis Ov, having a bottom and a circular cross section.

[0099] In addition, if Figure 5 As shown by the dotted line Lx in , the arrangement direction of the first gas injection valve 5A and the second gas injection valve 5B is inclined relative to the front-rear direction when viewed from above. The inclination angle is set to, for example, 1.0° or more and 6.0° or less, more specifically, 2.0° or more and 5.0° or less, and more specifically, 3.0° or more and 4.0° or less. By making it inclined in this way, it is possible to suppress the first gas injection valve 5A and the second gas injection valve 5B from interfering with other valve components, and it is possible to ensure the thickness of the cooling passage arranged in the cylinder head 15. It should be noted that the "other valve components" mentioned here include valve components that can be installed in the cylinder head 15, such as the fuel oil injection valve (FOV) and the premixing gas injection valve.

[0100] As described above, the first block 7A is placed on the first mounting surface 153A and the first gas injection valve 5A is supported by the first block 7A. On the other hand, the second block 7B is placed on the second mounting surface 153B and the second gas injection valve 5B is supported by the second block 7B.

[0101] The following, Figures 4 to 6 The left side of the paper, that is, the second block 7B and the second gas injection valve 5B will be described in detail. The following description is substantially the same as the description of the first block 7A and the first gas injection valve 5A.

[0102] (2) Specific Structure of Block 7 and Gas Injection Valve 5

[0103] Figure 7 yes Figure 5 AA section view, Figure 8 : is a longitudinal sectional view showing the structure of the gas injection valve 5. Fig. 9 Yes Figure 7 The enclosed portion XI is enlarged and shown in FIG. Fig.12 yes Figure 7 BB cross-sectional view. In addition, Fig.10 is a perspective view showing the structure of the block 7, Fig.11 1 is a longitudinal sectional view showing the structure of the block 7 .

[0104] like Figure 7 and Figure 8 As shown, the gas injection valve 5 includes a cylindrical body 50 and a valve stem 54 accommodated in the cylindrical body 50. The gas injection valve 5 is configured such that hydrogen gas is injected from an injection port 5a provided at the top end of the gas injection valve 5 when the valve stem 54 overcomes the spring force to open the valve.

[0105] It should be noted that in the following description, instead of various definitions based on the piston axis Op, Figure 6 to Figure 8 The direction along the center axis (hereinafter also referred to as "valve axis") Ov of the valve stem 54 shown in the figure is referred to as the "valve axis direction" or simply as the "axial direction". In addition, the direction radially extending from the valve axis Ov is referred to as the "radial direction", and the clockwise direction and the counterclockwise direction centered on the valve axis Ov are referred to as the "circumferential direction".

[0106] The radial direction is orthogonal to the valve axis direction. In addition, the side closer to the valve axis Ov in the radial direction is sometimes referred to as the "inner side", and the other side farther from the valve axis Ov in the radial direction is sometimes referred to as the "outer side".

[0107] In addition, sometimes the top end side of the gas injection valve 5 in the valve axis direction (the injection port 5a side in the same direction, i.e. Figure 7 and Figure 8 The lower side of the paper) is referred to as the "top end side", and the base end side of the gas injection valve 5 in the valve axis direction (the opposite side of the injection port 5a in the same direction, i.e. Figure 7 and Figure 8 The upper side on the paper) is referred to as the “base end side”.

[0108] Specifically, the gas injection valve 5 according to the present embodiment includes a biasing member 55 , an oil chamber 56 , and a first internal flow path 57 in addition to the above-mentioned cylindrical body 50 and valve stem 54 .

[0109] The cylindrical body 50 has, in order from the base end to the tip end in the valve axis direction, a first body 51 for accommodating the biasing member 55, a second body 52 for accommodating the valve stem 54, and a third body 53 provided with the injection port 5a.

[0110] like Figure 7 As shown in FIG. 1 , the first main body 51 is formed into a bottomed cylindrical shape with its base end side as a bottomed surface and its top end side as an open end, and accommodates a biasing member 55 composed of a compression coil spring or the like. Figure 7As shown, the base end portion of the valve stem 54 is pressed and biased toward the tip end side in the valve axis direction.

[0111] In addition, back to Figure 6 The base end of the first main body 51 forms a flange 51a with a partially enlarged diameter. As shown in the figure, a first fastener 81 composed of a bolt or the like is inserted into the flange 51a. The insertion direction of the first fastener 81 is set to be parallel to the valve axis direction.

[0112] like Figure 7 and Figure 8 As shown, the third main body 53 is formed into a substantially cylindrical shape with its base end side opened. The substantially cylindrical hollow portion constitutes a second internal flow path 53a extending along the valve axis direction. The second internal flow path 53a is opened and closed by the top end of the valve stem 54. The downstream end (top end) of the second internal flow path 53a is connected to the above-mentioned injection port 5a.

[0113] In this embodiment, the third body 53 is embedded in the insertion hole 154. The insertion hole 154 is formed as a through hole penetrating the cylinder head 15, particularly the semicircular portion 151 thereof, so that the injection port 5a is exposed to the combustion chamber 17 through the through hole.

[0114] like Figure 7 and Figure 8 As shown in FIG. 1 , the second main body 52 is formed in a substantially cylindrical shape with its distal end and proximal end opened. A valve stem 54 is inserted into the substantially cylindrical hollow portion.

[0115] Here, the distal end portion of the first body portion 51 is attached to the opening portion on the proximal end side of the second body portion 52. The proximal end portion of the valve stem 54 is pressed by the distal end of the urging member 55 by this attachment.

[0116] The base end of the third body 53 is inserted into the opening on the tip side of the second body 52. ​​By this insertion, the tip of the valve stem 54 comes into contact with or separates from the upstream end (base end) of the second internal flow path 53a.

[0117] In addition, in the hollow portion of the second body 52 (the hollow portion into which the valve stem 54 is inserted), the diameter of a portion in the valve axis direction is larger than the diameter of the outer peripheral surface of the valve stem 54. An oil chamber 56 to which the working oil is supplied is defined by the inner peripheral surface of the enlarged diameter portion and the outer peripheral surface of the valve stem 54. By increasing the oil pressure in the oil chamber 56, the valve stem 54 is moved upward by the force acting on the enlarged diameter portion of the valve stem 54. By moving the valve stem 54 upward, the second internal flow path 53a can be opened.

[0118] The second main body 52 is configured such that its tip end portion is embedded in the insertion hole 154 and its base end portion is exposed from the insertion hole 154 and inserted into the block 7. The first internal flow path 57 in the gas injection valve 5 opens at the outer peripheral surface of the base end portion of the second main body 52, of the tip end portion and the base end portion.

[0119] In detail, the first internal flow path 57 is configured to open on the outer peripheral surface of the gas injection valve 5 (particularly the outer peripheral surface of the base end side portion of the second main body 52) and connect the second gas supply passage 33 and the injection port 5a. It should be noted that the outer peripheral surface here does not refer to the end surface orthogonal to the valve axis direction, but refers to the side surface extending along the valve axis direction. The outer peripheral surface of the gas injection valve 5 faces radially outward.

[0120] In more detail, the outer peripheral surface of the second main body 52 has a first outer peripheral surface 52a, a third outer peripheral surface 52c and a second outer peripheral surface 52b in the order from the top end side to the base end side in the valve axis direction. The first outer peripheral surface 52a extends along the valve axis direction. The second outer peripheral surface 52b is arranged at a position closer to the base end side than the first outer peripheral surface 52a, has a diameter larger than the diameter of the first outer peripheral surface 52a, and extends along the valve axis direction. The third outer peripheral surface 52c is arranged between the first outer peripheral surface 52a and the second outer peripheral surface 52b in the valve axis direction. The third outer peripheral surface 52c is composed of a step or an inclined surface (in the example, an inclined surface) connecting the first outer peripheral surface 52a and the second outer peripheral surface 52b.

[0121] The first outer peripheral surface 52a has a circular cross section and is configured so that its top end side portion ( Figure 8 The section Lt) is embedded in the insertion hole 154 and the base end side portion ( Figure 8 The section Lp) is exposed from the insertion hole 154 and inserted into the block 7.

[0122] In addition, if Figure 8 As shown, the first recess 50a and the second recess 50b are provided on the base end side portion of the first outer peripheral surface 52a. The first recess 50a is formed into a groove extending around the entire circumference. The second recess 50b is arranged at a position closer to the base end side than the first recess 50a, and is formed into a groove extending around the entire circumference.

[0123] The second outer peripheral surface 52 b has a circular cross section with a larger diameter (larger in the radial direction) than the first outer peripheral surface 52 a , and is configured so that the entire surface from the top end to the base end is exposed from the insertion hole 154 and inserted into the block 7 .

[0124] In addition, if Figure 8As shown in the figure, a third recess 50c and a fourth recess 50d are provided on the second outer peripheral surface 52b. The third recess 50c is formed into a groove shape extending in the circumferential direction and having a diameter greater than that of the first recess 50a and the second recess 50b. The fourth recess 50d is arranged at a position closer to the base end side than the third recess 50c, and is formed into a groove shape extending in the circumferential direction and having the same diameter as that of the third recess 50c.

[0125] The third outer peripheral surface 52 c has a circular cross section with a diameter gradually decreasing from the base end side toward the tip end side, and is configured so that the entire surface from the tip end to the base end is exposed from the insertion hole 154 and arranged inside the block 7 .

[0126] In addition, if Figure 8 As shown, the upstream end of the first internal flow path 57 opens at the boundary between the first outer peripheral surface 52a and the third outer peripheral surface 52c. In this embodiment, the first internal flow path 57 opens at the base end (the upper end on the paper) of the first outer peripheral surface 52a. In addition, the upstream end of the first internal flow path 57 opens perpendicularly to the first outer peripheral surface 52a. In addition, as shown in FIG. Fig.12 As shown, the first internal flow paths 57 are provided approximately every 90 degrees in the circumferential direction.

[0127] In detail, the first internal flow path 57 has an upstream passage 57a and a downstream passage 57b in order from the upstream side to the downstream side. The upstream passage 57a opens at the base end (the upper end on the paper) of the first outer peripheral surface 52a and extends radially inward from the base end. The upstream passage 57a includes the upstream end of the first internal flow path 57. The downstream passage 57b extends from the upstream passage 57a and extends obliquely toward the second internal flow path 53a.

[0128] In addition, if Figure 8 As shown in the figures, four sealing members 61 to 64 are mounted on the outer peripheral surface of the gas injection valve 5. Specifically, the four sealing members 61 to 64 are composed of a first sealing member 61 and a second sealing member 62 mounted on the first outer peripheral surface 52a, and a third sealing member 63 and a fourth sealing member 64 mounted on the second outer peripheral surface 52b, in order from the top end side toward the base end side of the gas injection valve 5.

[0129] Specifically, the first seal member 61 is installed in the first recess 50a, the second seal member 62 is installed in the second recess 50b, the third seal member 63 is installed in the third recess 50c, and the fourth seal member 64 is installed in the fourth recess 50d. The first seal member 61 to the fourth seal member 64 are all composed of O-rings extending in the circumferential direction.

[0130] On the other hand, Fig.10As shown in FIG. 1 and FIG. 2 , the block 7 includes a rectangular parallelepiped portion 70 formed in a substantially rectangular parallelepiped shape. The block 7 is provided with an insertion hole 74 for inserting the corresponding gas injection valve 5. In the present embodiment, the rectangular parallelepiped portion 70 of the block 7 is made of solid steel (for example, forged steel).

[0131] In detail, the rectangular portion 70 involved in this embodiment has a front surface 70f facing approximately forward, a rear surface 70b facing approximately rearward, a left surface 701 facing approximately left, a right surface 70r facing approximately right, an upper surface 70t facing approximately upward, and a lower surface 70u facing approximately downward.

[0132] Furthermore, the insertion hole 74 provided in the block 7 is formed as a through hole extending from the upper surface 70t to the lower surface 70u, and is surrounded from four sides by the front surface 70f, the rear surface 70b, the left surface 70l, and the right surface 70r.

[0133] Specifically, if Fig. 9 As shown in the figures, the inner circumference of the insertion hole 74 has a first inner circumference 74a, a third inner circumference 74c and a second inner circumference 74b in order from the top end side to the base end side in the valve axis direction. The first inner circumference 74a extends along the valve axis direction and contacts the first outer circumference 52a of the gas injection valve 5. The second inner circumference 74b extends along the valve axis direction in the same manner as the first inner circumference 74a. The second inner circumference 74b is arranged at a position closer to the base end side than the first inner circumference 74a, has a larger diameter than the first inner circumference 74a and contacts the second outer circumference 52b. The third inner circumference 74c is arranged between the first inner circumference 74a and the second inner circumference 74b in the valve axis direction. The third inner circumference 74c is composed of a step or an inclined surface (in the example, an inclined surface) connecting the first inner circumference 74a and the second inner circumference 74b. The inner circumference of the insertion hole 74 faces radially inward.

[0134] In addition, if Fig. 9 and Fig.10 As shown, the first inner peripheral surface 74a is provided with a first groove portion 77 extending in the circumferential direction along the first inner peripheral surface 74a. The dimension of the first groove portion 77 in the axial direction is at least narrower than the interval between the first recessed portion 50a and the second recessed portion 50b (in other words, the interval between the first sealing member 61 and the second sealing member 62).

[0135] In addition, if Fig. 9 and Fig.10 As shown, the second inner peripheral surface 74b is provided with a second groove portion 78 extending in the circumferential direction along the second inner peripheral surface 74b. The axial dimension of the second groove portion 78 is at least narrower than the interval between the third recess 50c and the fourth recess 50d (in other words, the interval between the third sealing member 63 and the fourth sealing member 64).

[0136] The lower surface 70u of the block 7 is mounted on the upper surface of the cylinder head 15, particularly on the first mounting surface 153A or the second mounting surface 153B. The second gas supply passage 33 opens at the lower surface 70u and the insertion hole 74 of the block 7.

[0137] That is, the second gas supply passage 33 involved in this embodiment has an upstream end 33a and a downstream end 33b, wherein the upstream end 33a opens at the lower surface 70u of the block 7, and the downstream end 33b opens at the inner peripheral surface (particularly the boundary between the second inner peripheral surface 74b and the third inner peripheral surface 74c) of the insertion hole 74. In addition, at least a portion of the second gas supply passage 33 extends from the upstream end 33a side toward the downstream end 33b at an angle relative to the valve axis direction.

[0138] In particular, in the present embodiment, the upstream end portion 33a is Fig.11 In the left-right direction of the paper surface), it is arranged at a position closer to the outside than the downstream end 33b. Fig.11 As shown, the upstream end portion 33 a opens at a portion of the lower surface 70 u located radially outside the insertion hole 74 and the downstream end portion 33 b and inside the second fastening hole 73 .

[0139] In addition, the downstream end portion 33b opens at the second inner peripheral surface 74b or the third inner peripheral surface 74c in the inner peripheral surface of the block 7. In detail, the downstream end portion 33b opens at the boundary between the second inner peripheral surface 74b and the third inner peripheral surface 74c. In the present embodiment, the downstream end portion 33b opens at the top end portion (the lower end portion on the paper) of the second inner peripheral surface 74b. In addition, the downstream end portion 33b opens obliquely relative to the second inner peripheral surface 74b.

[0140] More specifically, the second gas supply passage 33 includes a first portion 75 and a second portion 76. The first portion 75 extends upward in the height direction from the upstream end portion 33a of the second gas supply passage 33. The second portion 76 continues from the first portion 75 and extends to the downstream end portion 33b in a manner that the further upward the second portion 76 is, the more inclined it is to the radially inner side. It should be noted that the “height direction” referred to here refers to Figure 3 to Figure 6 The "upper direction" in this embodiment substantially coincides with the direction toward the base end side in the valve axis direction.

[0141] And, if Fig.11As shown, the dimension L2 of the second portion 76 in the flow direction of hydrogen is longer than the dimension L1 of the first portion 75 in the flow direction. It should be noted that the "flow direction of hydrogen" referred to here refers to the direction in which hydrogen flows from the upstream end 33a of the second gas supply passage 33 toward the downstream end 33b. In this embodiment, the flow direction is bent at the boundary between the first portion 75 and the second portion 76.

[0142] In addition, if Figure 10 to Figure 12 As shown, the block 7 has two first fastening holes 72 in a group on the upper surface 70 t of the rectangular parallelepiped portion 70 , and second fastening holes 73 arranged at four corners of the upper surface 70 t .

[0143] The first fastening hole 72 is a fastening hole for fastening the gas injection valve 5 to the block 7, and is inserted into the first fastening member 81. The first fastening hole 72 does not penetrate the block 7 in the thickness direction. In other words, the inner bottom of the first fastening hole 72 is as shown in FIG. Fig.10 and Fig.11 The partitions are formed inside the block 7 as shown.

[0144] The second fastening hole 73 is a fastening hole for fastening the block 7 to the upper surface 15a of the cylinder head 15, and a second fastening member 82 composed of a bolt or the like is inserted. The second fastening hole 73 penetrates the block 7 in the thickness direction. That is, although not shown in the figure, the inner bottom of the second fastening hole 73 is divided and formed inside the cylinder head 15.

[0145] like Fig.10 As shown, the second fastening hole 73 is arranged at a radially outer position than the first fastening hole 72. In addition, both the first fastening hole 72 and the second fastening hole 73 extend along the valve axis direction. The gas injection valve 5 is fastened to the block 7 by using the first fastening hole 72 and the first fastener 81, and the block 7 is fastened to the cylinder head 15 by using the second fastening hole 73 and the second fastener 82.

[0146] And, if Fig. 9 As shown, when the gas injection valve 5 is fastened to the block 7, the third outer peripheral surface 52c of the gas injection valve 5 and the third inner peripheral surface 74c of the block 7 are opposite to each other with a gap in the axial direction or the radial direction (in the example, in the axial direction). Fig. 9 and Fig.12 As shown, the gap defines a first space S1 through which hydrogen gas flows in a circumferential direction around the central axis Ov of the gas injection valve 5 .

[0147] In more detail, Fig. 9 As shown, the first space S1 is surrounded by the base end (upper end on the paper) of the first outer peripheral surface 52a, the third outer peripheral surface 52c, the top end (lower end on the paper) of the second inner peripheral surface 74b and the third inner peripheral surface 74c, forming Fig.12 The annular space shown.

[0148] As described above, the first internal flow path 57 opens at the base end of the first outer peripheral surface 52a. That is, the first internal flow path 57 as a gas introduction passage opens in a manner communicating with the first space S1 (see Fig.12 ). Similarly, the second gas supply passage 33 opens at the top end of the second inner peripheral surface 74b as described above. That is, the second gas supply passage 33 also opens in a manner communicating with the first space S1 (see Fig. 9 ).

[0149] The first space S1 functions as a connection portion, a so-called "gas storage portion", where the second gas supply passage 33 is connected to the gas injection valve 5. The sealing members 62 and 63 involved in this embodiment are provided in the first space S1 as a connection portion, and are provided at least on the first outer peripheral surface 52a in order to suppress leakage of gas passing through the first space S1.

[0150] In the present embodiment, among the first to fourth sealing members 61 to 64 , the second and third sealing members 62 and 63 are equivalent to sealing members for directly sealing the first space S1 , and the first and fourth sealing members 61 and 64 are equivalent to sealing members for doubly sealing the first space S1 .

[0151] As described above, the first sealing member 61 and the second sealing member 62 are provided on the first outer peripheral surface 52a, and the third sealing member 63 and the fourth sealing member 64 are provided on the second outer peripheral surface 52b. In order to realize a double sealing structure on both the top end side and the base end side in the axial direction, the upstream end (opening) of the first internal flow path 57 is as shown in FIG. Figure 8 As shown in the figure, it is arranged between the second sealing member 62 and the third sealing member 63 in the axial direction.

[0152] In addition, a second space S2 and a third space S3 are formed between the inner circumference of the insertion hole 74 and the outer circumference of the gas injection valve 5. The second space S2 and the third space S3 are used to allow hydrogen leaked from the first space S1 to flow in and discharge the hydrogen to the outside. The first space S1, the second space S2 and the third space S3 are all divided into annular spaces extending in the circumferential direction.

[0153] The second space S2 is defined between the first groove portion 77 formed on the first inner peripheral surface 74a and the first outer peripheral surface 52a opposite to the first groove portion 77. The second space S2 is located closer to the top end side than the first space S1 and is a space into which the hydrogen gas leaked from the first space S1 flows. The hydrogen gas flowing into the second space S2 is discharged through a flow path defined and formed inside the gas injection valve 5, a pipe not shown, and the like.

[0154] The third space S3 is defined between the second groove portion 78 formed on the second inner peripheral surface 74b and the second outer peripheral surface 52b opposite to the second groove portion 78. The third space S3 is located closer to the base end side than the first space S1 and is a space into which the hydrogen gas leaked from the first space S1 flows. The hydrogen gas flowing into the third space S3 is discharged through a flow path defined and formed inside the gas injection valve 5, a pipe not shown, and the like.

[0155] The first to fourth sealing members 61 to 64 not only form a double sealing structure for the first space S1 , but also have a function of sealing the second space S2 and the third space S3 .

[0156] Specifically, the first sealing member 61 is located on the distal end side of the second space S2 and is attached to the first outer peripheral surface 52 a so as to be sandwiched between the first outer peripheral surface 52 a and the first inner peripheral surface 74 a .

[0157] The second sealing member 62 is located closer to the proximal end than the second space S2 and is attached to the first outer peripheral surface 52 a so as to be sandwiched between the first outer peripheral surface 52 a and the first inner peripheral surface 74 a .

[0158] The third sealing member 63 is located on the distal end side of the third space S3 and is attached to the second outer peripheral surface 52 b so as to be sandwiched between the second outer peripheral surface 52 b and the second inner peripheral surface 74 b .

[0159] The fourth sealing member 64 is located closer to the proximal end than the third space S3 and is attached to the second outer peripheral surface 52 b so as to be sandwiched between the second outer peripheral surface 52 b and the second inner peripheral surface 74 b .

[0160] The first sealing member 61 and the second sealing member 62 seal not only the first space S1 but also the second space S2. The third sealing member 63 and the fourth sealing member 64 seal not only the first space S1 but also the third space S3.

[0161] In addition, a lower surface 70u of the block 7, particularly the lower surface 70u around the upstream end 33a of the second gas supply passage 33, is provided with a Fig.10 and Fig.11 The first annular groove 791 and the second annular groove 792 are shown.

[0162] A fifth sealing member 65 (refer to the fifth sealing member 65) composed of an O-ring or the like is sandwiched between the first annular groove 791 and the upper surface 15a of the cylinder head 15, in particular, the first mounting surface 153A or the second mounting surface 153B. Figure 7 and Fig. 9 Similarly, a sixth sealing member 66 composed of an O-ring or the like is sandwiched between the second annular groove 792 and the upper surface 15a of the cylinder head 15, in particular, the first mounting surface 153A or the second mounting surface 153B (for the sixth sealing member 66, refer to Figure 7 and Fig. 9 ). The fifth sealing component 65 and the sixth sealing component 66 can be used to seal the gap between the block 7 and the upper surface 15a of the cylinder head 15. Specifically, by installing the fifth sealing component 65 in the first annular groove 791, the upstream end portion 33a opened on the lower surface 70u is sealed. Similarly, by installing the sixth sealing component 66 in the second annular groove 792, the upstream end portion 33a and the insertion hole 77 opened on the lower surface 70u like the upstream end portion 33a are sealed. Since these sealing components 65 and 66 are arranged on the upper surface of the cylinder head 15, they are advantageous in suppressing thermal damage compared to sealing components arranged inside the cylinder head 15.

[0163] (3) Significance of Block 7

[0164] As described above, according to the present embodiment, the gas injection valve 5 is not directly connected to the first gas supply passage 32 defined in the cylinder head 15, but is indirectly connected via the block body 7 formed separately from the cylinder head 15 (see Figure 3 , Figure 7 and Fig. 9 wait).

[0165] By connecting in this way, even without providing a sealing member in the cylinder head 15, the first to fourth sealing members 61 to 64 can be provided at the connection portion S1 between the block 7 and the gas injection valve 5 (the connection portion between the second gas supply passage 33 and the gas injection valve 5).

[0166] Here, since the block 7 is arranged on the upper surface of the cylinder head 15, the first to fourth sealing members 61 to 64 can be kept away from the combustion chamber 17, compared with a structure in which the sealing members are arranged inside the cylinder head 15. Therefore, by keeping the first to fourth sealing members 61 to 64 away from the combustion chamber 17, thermal damage to the first to fourth sealing members 61 to 64 can be suppressed.

[0167] As described above, according to the present embodiment, the first gas supply passage 32 can be provided in the cylinder head 15 while thermal damage to the first to fourth sealing members 61 to 64 can be suppressed.

[0168] Assume the following structure: No setting Fig. 9The third outer peripheral surface 52c and the third inner peripheral surface 74c shown in the figure are configured such that the diameter of the first outer peripheral surface 52a is the same as the diameter of the second outer peripheral surface 52b, and the diameter of the first inner peripheral surface 74a is the same as the diameter of the second inner peripheral surface 74b. If such a structure is adopted, when the gas injection valve 5 is inserted into the block 7, the sealing components (for example, the first sealing component 61 and the second sealing component 62) mounted on the first outer peripheral surface 52a of the gas injection valve 5 will rub against both the second inner peripheral surface 74b and the first inner peripheral surface 74a. In this case, there is a concern that the first sealing component 61 and the second sealing component 62 may be damaged due to wear.

[0169] In contrast, according to the present embodiment, the second inner peripheral surface 74b is as follows Fig.11 As shown in the figure, the diameter of the first inner peripheral surface 74a is larger than the diameter of the first inner peripheral surface 74a. Therefore, when the gas injection valve 5 is inserted into the block 7, the sealing component 61 mounted on the first outer peripheral surface 52a of the gas injection valve 5 can be prevented from contacting the second inner peripheral surface 74b. As a result, it is possible to prevent the first sealing component 61 and the second sealing component 62 from being damaged by the contact. In addition, by making the diameter of the second inner peripheral surface 74b larger and the diameter of the second outer peripheral surface 52b larger than the diameter of the first outer peripheral surface 52a, the contact between the inner peripheral surface of the insertion hole 74 and the outer peripheral surface of the gas injection valve 5 can be maintained. This helps to prevent leakage of hydrogen.

[0170] In addition, by using the third outer peripheral surface 52c and the third inner peripheral surface 74c to divide and form the first space S1, a gas storage portion for gas fuel to flow in the circumferential direction can be formed even if a groove is not newly provided on the outer peripheral surface of the gas injection valve 5. Usually, grooving is required to make such a groove, but this embodiment does not require such processing, so no special tool for grooving is required. As a result, the ease of processing of the engine 1 can be improved.

[0171] That is, the third outer peripheral surface 52c and the third inner peripheral surface 74c involved in this embodiment can simultaneously take into account the following aspects: suppressing the leakage of hydrogen, suppressing the damage to the first sealing component 61 and the second sealing component 62, allowing hydrogen to flow in the circumferential direction, and improving the machinability of the block 7.

[0172] In addition, if Figure 8 and Fig. 9 As shown, the second sealing member 62 and the third sealing member 63 are arranged on both sides of the first space S1 in the valve axis direction, and the first sealing member 61 and the fourth sealing member 64 are arranged on both sides slightly farther away. With such a layout, a double sealing structure can be realized in which the four sealing members 61, 62, 63, 64 are used to seal the first space S1.

[0173] In addition, by dividing the second space S2 between the first sealing member 61 and the second sealing member 62, and dividing the third space S3 between the third sealing member 63 and the fourth sealing member 64, not only a double sealing structure for the first space S1 can be realized, but also a sealing structure for sealing the second space S2 and the third space S3 respectively can be realized at the same time.

[0174] Assume the following structure: No setting Fig. 9 The third outer peripheral surface 52c and the third inner peripheral surface 74c shown in the figure are configured such that the diameter of the first outer peripheral surface 52a is the same as the diameter of the second outer peripheral surface 52b, and the diameter of the first inner peripheral surface 74a is the same as the diameter of the second inner peripheral surface 74b. If such a structure is adopted, when the gas injection valve 5 is inserted into the block 7, the first sealing member 61 and the second sealing member 62 mounted on the first outer peripheral surface 52a of the gas injection valve 5 will rub against both the second inner peripheral surface 74b and the first inner peripheral surface 74a. In this case, when the first sealing member 61 and the second sealing member 62 rub against the second inner peripheral surface 74b, there is a particular concern about the friction between the first sealing member 61 and the second sealing member 62 and the second groove 78 provided on the second inner peripheral surface 74b.

[0175] In contrast, according to the present embodiment, when the gas injection valve 5 is inserted into the block body 7, the first sealing member 61 and the second sealing member 62 mounted on the first outer peripheral surface 52a of the gas injection valve 5 can be prevented from contacting the second inner peripheral surface 74b or the second groove 78 provided on the second inner peripheral surface 74b. This is advantageous in preventing the first sealing member 61 and the second sealing member 62 from being damaged by the contact.

[0176] In addition, if Figure 8 As shown in the figures, by opening the upstream end (upstream side passage 57a) of the first internal flow path 57 vertically relative to the second outer peripheral surface 52b, the opening area can be reduced as much as possible compared to, for example, opening the upstream end obliquely. Reducing the opening area is very effective in shortening the interval between the second sealing member 62 and the third sealing member 63 in the valve axis direction. Shortening the interval helps to reduce the volume of the first space S1. In addition, reducing the volume of the first space S1 is very advantageous in reducing the amount of hydrogen that can be accumulated in the space S1 and further improving safety. As such, the structure of the gas injection valve 5 involved in this embodiment is very suitable for the case where hydrogen is used as the gas fuel.

[0177] In addition, if Figure 8 and Fig. 9As shown in FIG. 1 , by opening the upstream end (upstream passage 57a) of the first internal flow path 57 at the boundary between the first outer peripheral surface 52a and the third outer peripheral surface 52c, the interval between the second sealing member 62 and the third sealing member 63 in the valve axis direction can be shortened compared with a structure in which the upstream end (upstream passage 57a) of the first internal flow path 57 is opened at the top end (for example, the boundary between the second main body 52 and the third main body 53) of the first outer peripheral surface 52a. As a result, the volume of the first space S1 can be reduced, and the amount of hydrogen that can be accumulated in the space S1 can be reduced. This is very advantageous in further improving safety.

[0178] In addition, when using solid steel, it is generally considered to process the second gas supply passage 33 by combining a through hole extending in the valve axis direction and a through hole extending in a radial direction orthogonal thereto. However, when such through holes in two directions are provided, so-called dead holes are generated, and it is necessary to block the dead holes with a sealing plug or the like. However, the use of a sealing plug is not appropriate because it may cause hydrogen leakage and hydrogen embrittlement due to accumulation of hydrogen in the closed portion formed by the sealing plug.

[0179] In contrast, the second gas supply passage 33 according to this embodiment is as follows: Fig.11 As shown in FIG. 1 , the second portion 76 extending obliquely is provided. Thus, even without using a dead hole or a sealing plug, the second gas supply passage 33 can be formed. This contributes to suppressing hydrogen leakage and hydrogen embrittlement.

[0180] In addition, if Fig.11 As shown in the figures, by making the dimension L2 of the second portion 76 relatively longer than the dimension L1 of the first portion 75, the second gas supply passage 33 can be extended obliquely for a longer period. By making the second gas supply passage 33 extend obliquely for a longer period, the hydrogen gas can be smoothly guided to the downstream end 33b of the second gas supply passage 33 and further to the gas injection valve 5 without the hydrogen gas staying in the middle of the second gas supply passage 33.

[0181] <Other Embodiments>

[0182] In the above embodiment, the first groove 77 is provided on the first inner peripheral surface 74a and the second groove 78 is provided on the second inner peripheral surface 74b, but the present disclosure is not limited to this structure. For example, the first groove 77 may be provided on the first outer peripheral surface 52a opposite to the first inner peripheral surface 74a, and the second groove 78 may be provided on the second outer peripheral surface 52b opposite to the second inner peripheral surface 74b.

Claims

1. A gas engine capable of burning gaseous fuel in a cylinder, characterized in that: The gas engine comprises a cylinder liner, a cylinder head, a gas injection valve, a gas supply passage, a block and a sealing component. The cylinder sleeve allows the piston to reciprocate. The cylinder head is fixed to the upper end of the cylinder liner as the cover of the cylinder. The gas injection valve is provided with an injection port for injecting the gas fuel into the cylinder. The gas supply passage supplies the gas fuel to the gas injection valve. The block is fixed to the upper surface of the cylinder head, the gas injection valve is inserted into the block, and the block and the cylinder head are separate bodies. The sealing member seals a gap between the gas supply passage and the gas injection valve. The gas supply passage includes a first gas supply passage and a second gas supply passage, The first gas supply passage is defined and formed inside the cylinder head. The second gas supply passage is divided and formed inside the block, and connects the first gas supply passage and the gas injection valve. The sealing member is provided at a connection portion between the second gas supply passage and the gas injection valve.

2. The gas engine according to claim 1, characterized in that: The gas engine also includes a gas introduction passage and a socket, The gas introduction passage opens at the outer peripheral surface of the gas injection valve and connects the second gas supply passage and the injection port. The plug hole is provided on the block for inserting the gas injection valve. In the axial direction of the gas injection valve, if the injection port side in the axial direction is the tip side, and the opposite side of the injection port in the axial direction is the base end side, The outer peripheral surface of the gas injection valve includes a first outer peripheral surface, a second outer peripheral surface and a third outer peripheral surface. The first outer peripheral surface extends along the axial direction, The second outer peripheral surface is arranged at a position closer to the base end than the first outer peripheral surface, the diameter of the second outer peripheral surface is larger than the diameter of the first outer peripheral surface, and the second outer peripheral surface extends along the axial direction. The third outer peripheral surface is composed of a step or an inclined surface connecting the first outer peripheral surface and the second outer peripheral surface. The inner circumference of the jack includes a first inner circumference, a second inner circumference and a third inner circumference. The first inner peripheral surface is in contact with the first outer peripheral surface, The second inner peripheral surface is arranged at a position closer to the base end than the first inner peripheral surface, the diameter of the second inner peripheral surface is larger than the diameter of the first inner peripheral surface, and the second inner peripheral surface is in contact with the second outer peripheral surface. The third inner peripheral surface is composed of a step or an inclined surface connecting the first inner peripheral surface and the second inner peripheral surface. In a state where the gas injection valve is fastened to the block, the third outer peripheral surface and the third inner peripheral surface are opposed to each other with a gap therebetween in the axial direction or in a radial direction orthogonal to the axial direction. The gap defines a first space through which the gas fuel flows in a circumferential direction around the central axis of the gas injection valve. The gas introduction passage is opened in a manner communicating with the first space, The sealing member is installed at least on the first outer peripheral surface to suppress leakage of gas through the first space.

3. The gas engine according to claim 2, characterized in that: The gas engine further comprises a second space and a third space, The second space is formed between the first outer peripheral surface and the first inner peripheral surface, is located closer to the tip side than the first space, and allows the gas fuel leaking from the first space to flow in. The third space is formed between the second outer peripheral surface and the second inner peripheral surface, is located closer to the base end than the first space, and allows the gas fuel leaked from the first space to flow in. The sealing member is composed of a first sealing member, a second sealing member, a third sealing member, and a fourth sealing member in order from the distal end side toward the proximal end side. The first sealing member is located on the tip side relative to the second space and is mounted on the first outer peripheral surface so as to be sandwiched between the first outer peripheral surface and the first inner peripheral surface. The second sealing member is located on the base end side relative to the second space and is attached to the first outer peripheral surface so as to be sandwiched between the first outer peripheral surface and the first inner peripheral surface. The third sealing member is located on the tip side relative to the third space and is mounted on the second outer peripheral surface so as to be sandwiched between the second outer peripheral surface and the second inner peripheral surface. The fourth sealing member is located on the base end side relative to the third space and is attached to the second outer peripheral surface so as to be sandwiched between the second outer peripheral surface and the second inner peripheral surface. An upstream end portion of the gas introduction passage is disposed between the second sealing member and the third sealing member in the axial direction.

4. The gas engine according to claim 3, characterized in that: The first sealing member and the second sealing member are installed in a recessed portion provided on the first outer peripheral surface. The third sealing member and the fourth sealing member are installed in a recessed portion provided on the second outer peripheral surface. The second space is defined by a groove provided on the first inner peripheral surface and the first outer peripheral surface opposite to the groove. The third space is defined by a groove provided in the second inner peripheral surface and the second outer peripheral surface facing the groove.

5. The gas engine according to claim 3, characterized in that: The gaseous fuel is hydrogen, An upstream end portion of the gas introduction passage opens perpendicularly to the first outer peripheral surface.

6. The gas engine according to claim 5, characterized in that: An upstream end portion of the gas introduction passage opens at a boundary portion between the first outer peripheral surface and the third outer peripheral surface.

7. The gas engine according to claim 1, characterized in that: The gaseous fuel is hydrogen, The block is made of solid steel. The block has a lower surface and a socket, The lower surface is mounted on the upper surface of the cylinder head, The gas injection valve is inserted into the socket. The second gas supply passage has an upstream end and a downstream end, The upstream end is open on the lower surface, The downstream end portion opens on the inner peripheral surface of the insertion hole, The upstream end portion is arranged at an outer side than the downstream end portion in a radial direction orthogonal to the axial direction of the gas injection valve. The second gas supply passage further comprises a first portion and a second portion, The first portion extends upward from the upstream end portion, The second portion continues to the first portion and extends to the downstream end portion in a manner that inclines toward the inner side in the radial direction as it goes upward in the height direction.

8. The gas engine according to claim 7, characterized in that: A dimension of the second portion in a flow direction of the gas fuel is longer than a dimension of the first portion in the flow direction.

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