Cylinder head, cylinder head assembly, piston engine, connection block and method for detecting gas fuel leakage in piston engine

Abstract

A cylinder head (1) for a piston engine has a bottom surface (1A) configured to define a main combustion chamber (2) and a top surface (1B) facing in an opposite direction and configured to receive an intake valve assembly (4) attachable to the cylinder head (1), the cylinder head (1) comprises a pre-chamber bore (7), an intake passage (11) for introducing intake air into the main combustion chamber (2), and a gas supply passage (12) for introducing gaseous fuel into the intake passage (11), the gas supply passage (12) having a first end (12A) leading to the top surface (1B) and a second end leading to the intake passage (11). The cylinder head (1) further comprises an auxiliary passage (13, 14) having a first end (13A, 14A) leading to the top surface (1B) and a second end (13B, 14B) leading to the pre-chamber bore (7), the first end (13A, 14A) being located in an area configured to be covered by the intake valve assembly (4).

Description

Technical Field

[0001] The invention relates to a cylinder head for a piston engine as defined in the preamble of claim 1. The invention also relates to a cylinder head assembly for a piston engine and a piston engine. The invention also relates to a connecting block for attaching an intake valve to a cylinder head and a method for detecting a gaseous fuel leak in a piston engine. Background Art

[0002] In large piston engines, for example in engines used as main engines or auxiliary engines in ships or in engines used in power plants for generating electricity, each cylinder of the engine is provided with its own cylinder head. The cylinder head closes the upper end of the cylinder and defines the main combustion chamber. In a four-stroke engine, the cylinder head serves several purposes. For example, the cylinder head is provided with an intake duct for introducing intake air into the combustion chamber and an exhaust port for discharging exhaust gases from the combustion chamber. The intake valves and exhaust valves are arranged in the cylinder head. In particular, gas engines or dual-fuel or multi-fuel engines that can be operated using gaseous fuels are usually provided with a pre-combustion chamber. The engine is usually operated in gas mode using a lean air-fuel mixture, and the pre-combustion chamber allows a richer mixture to be formed in the pre-combustion chamber, thereby promoting the ignition of the lean mixture in the main combustion chamber. The main part of the pre-combustion chamber is arranged in the cylinder head.

[0003] The use of gaseous fuels brings many benefits, such as reduced emissions. However, leaking gaseous fuels pose a safety risk and, therefore, certain protective measures are required in engines that can be operated using gaseous fuels. Particularly in marine applications, stringent safety requirements are set by classification societies. One of the requirements set for gas engines is that, in most cases, the gaseous fuel needs to be guided in double-walled pipes. Double-walled pipes consist of an inner pipe, in which the fuel is guided, and an outer pipe, which forms a protective sheath around the inner pipe. If there is a leak in the inner pipe, the leaking fuel is captured by the outer pipe. The space between the inner and outer pipes is usually ventilated to a safe place. In addition, this space can be monitored by a gas detector and, if a gas leak is detected, an alarm is triggered.

[0004] The need for double walled tubing and gas detectors makes gas engines more complex and expensive. Summary of the invention

[0005] The object of the present invention is to provide an improved cylinder head for a piston engine. The features of the cylinder head according to the invention are listed in the characterizing part of claim 1. Another object of the present invention is to provide an improved cylinder head assembly. Another object of the present invention is to provide an improved piston engine. Other objects of the present invention are to provide a connection block for attaching an intake valve to the upper surface of a cylinder head and a method for detecting gaseous fuel leakage in a piston engine.

[0006] The cylinder head according to the present invention has a bottom surface and a top surface, wherein the bottom surface is configured to define the upper end of the main combustion chamber of the cylinder of the piston engine, and the top surface faces the direction opposite to the bottom surface, and the top surface is configured to receive an intake valve assembly that can be attached to the cylinder head. The cylinder head includes a pre-combustion chamber hole, an intake passage for introducing intake air into the main combustion chamber, and a supply passage for introducing gaseous fuel from the intake valve into the intake passage, the supply passage having a first end leading to the top surface of the cylinder head and a second end leading to the intake passage of the cylinder head. The cylinder head also includes an auxiliary passage, wherein the auxiliary passage has a first end leading to the top surface of the cylinder head and a second end leading to the pre-combustion chamber hole, wherein the first end of the auxiliary passage is located in an area configured to be covered by the intake valve assembly.

[0007] The auxiliary channel can be used to deliver the gaseous fuel to be injected, or it can be used as a leakage channel for gaseous fuel that may leak. The channel located in the cylinder head does not need to be a double-walled tube. Since the auxiliary channel leads to an area that is configured to be covered by the intake valve assembly, the number of components in the air supply system can be reduced. This makes the system less complex and reduces the number of possible gas leakage locations.

[0008] According to an embodiment of the present invention, the first end of the auxiliary passage is positioned at a distance from the first end of the air supply passage, so that when the intake valve assembly is attached to the cylinder head, the first end of the auxiliary passage leads to the area between the inner wall surface and the outer wall surface of the intake valve assembly. Therefore, the intake valve assembly can be provided with a connection point for the auxiliary passage between the inner wall surface and the outer wall surface.

[0009] According to an embodiment of the present invention, the top surface of the cylinder head is provided with an inner sealing groove and an outer sealing groove around the first end of the air supply passage, each sealing groove is configured to receive a sealing element, and the first end of the auxiliary passage is located between the inner sealing groove and the outer sealing groove. This allows the auxiliary passage to be effectively sealed outwardly and toward the air supply passage.

[0010] According to an embodiment of the present invention, the top surface of the cylinder head is provided with a sealing groove arranged around the first end of the auxiliary passage. This allows the joint between the end of the auxiliary passage and the intake valve assembly to be effectively sealed.

[0011] According to an embodiment of the present invention, the auxiliary passage is a pre-combustion chamber air supply passage, and the second end of the auxiliary passage is arranged at a position that allows connection to a pre-combustion chamber injector for introducing gaseous fuel into the pre-combustion chamber. By using the auxiliary passage as the pre-combustion chamber air supply passage, the need for a double-walled pipe outside the cylinder head is avoided, which simplifies the construction of the fuel supply system.

[0012] According to an embodiment of the present invention, the auxiliary passage is a pre-combustion chamber gas leak detection passage, and the second end of the auxiliary passage is arranged at a position that allows possible leaked gas fuel to be discharged from the pre-combustion chamber hole. This allows the same leak detector to be used to detect gas fuel leaking from the pre-combustion chamber injector and from other places in the fuel supply system.

[0013] According to an embodiment of the present invention, the cylinder head further comprises a first auxiliary channel and a second auxiliary channel, the first auxiliary channel being a pre-combustion chamber air supply channel, and the second auxiliary channel being a pre-combustion chamber gas leakage detection channel.

[0014] A cylinder head assembly according to the present invention includes the cylinder head defined above and an intake valve assembly arranged on a top surface of the cylinder head.

[0015] According to an embodiment of the present invention, the intake valve assembly comprises a connection block for attaching the intake valve to the cylinder head, wherein the connection block is arranged against the top surface of the cylinder head and comprises an inner wall surface surrounding the first end of the air supply passage and an outer wall surface surrounding the first end of the air supply passage. The area between the inner wall surface and the outer wall surface can be used to provide a connection for one or more auxiliary passages.

[0016] According to an embodiment of the present invention, the auxiliary passage is configured to connect the pre-chamber hole to the intake valve assembly between the inner wall surface and the outer wall surface of the intake valve assembly. This allows the auxiliary passage to be connected to a leak detector.

[0017] A piston engine according to the invention comprises a cylinder head assembly as defined above.

[0018] The connection block for attaching an intake valve to the upper surface of the cylinder head defined above according to the present invention is configured to receive the intake valve and includes a gas passage configured to be connected to a first end of an auxiliary passage of the cylinder head.

[0019] According to an embodiment of the present invention, the gas passage is configured to be connected to a gas supply space formed between the connection block and the intake valve in a mounted state of the intake valve. This allows gas to be supplied through the auxiliary passage.

[0020] According to an embodiment of the present invention, the gas passage is configured to connect the auxiliary passage of the cylinder head to the leak detector. This allows the auxiliary passage to be used as a gas leak detection passage.

[0021] According to an embodiment of the present invention, the connection block includes a first gas channel configured to be connected to a first end of a first auxiliary channel of a cylinder head, and a second gas channel configured to be connected to a first end of a second auxiliary channel of a cylinder head. Therefore, the gas channel of the connection block can be connected to both the pre-combustion chamber gas supply channel and the pre-combustion chamber gas leakage detection channel.

[0022] The method according to the invention for detecting a gaseous fuel leak in a piston engine comprises the following steps:

[0023] - introducing intake air into a main combustion chamber of a cylinder of the engine via an intake duct located in a cylinder head of the cylinder;

[0024] - introducing gaseous fuel from an intake valve assembly attached to the cylinder head into the intake passage through an air supply passage arranged in the cylinder head and having a first end opening to a top surface of the cylinder head and a second end opening to the intake passage;

[0025] - directing possible leaking fuel from the pre-combustion chamber assembly via an auxiliary channel to the intake valve assembly and further to a leak detector; and

[0026] - Using the leak detector to detect gaseous fuel directed via the secondary passage.

[0027] In the method according to the invention, the auxiliary channel thus serves as a leakage channel which guides the possibly leaking fuel to the leak detector. This reduces the number of joints in the fuel supply system of the engine.

[0028] According to an embodiment of the invention, the leak detector is a gas detector or a pressure sensor.

[0029] According to an embodiment of the invention, the leak detector is used to monitor a possible gas leak from a gas supply pipe supplying gaseous fuel to an intake valve assembly.Thus, the same leak detector is used to detect gas leaks from both the pre-combustion chamber assembly and the gas supply pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings, in which:

[0031] Figure 1 A perspective view of a cylinder head according to an embodiment of the present invention is shown;

[0032] Figure 2 Shows Figure 1 an enlarged view of detail E;

[0033] Figure 3 A cross-sectional view showing a cylinder head assembly according to an embodiment of the present invention; and

[0034] Figure 4 Shows Figure 3 Another cross-sectional view of the cylinder head assembly. DETAILED DESCRIPTION

[0035] Figure 1A cylinder head 1 according to an embodiment of the invention is shown. The cylinder head 1 is a cylinder head of a large piston engine. The expression "large piston engine" here refers to an engine having a cylinder diameter of at least 150 mm. For example, the engine may be an engine used as a main engine or an auxiliary engine in a ship or an engine used in a power plant to drive a generator to generate electricity. The engine is a four-stroke engine. Figure 3 and Figure 4 Schematically shown is the upper part of a cylinder 3, to which a cylinder head 1 according to an embodiment of the invention is connected. Each cylinder 3 of the engine is provided with its own cylinder head 1. The cylinder head 1 may be a one-piece part.

[0036] The engine in which the cylinder head 1 is used is configured to operate using at least a first gaseous fuel. The expression "gaseous fuel" refers here to a fuel that is gaseous at atmospheric pressure and a temperature of 20° C. For example, the first fuel may be natural gas or biogas. The term "biogas" refers here to a gas that consists mainly of methane and is obtained from a renewable source. Biogas may, for example, be produced from organic waste. Natural gas may be stored as liquefied gas (LNG) or compressed gas (CNG). Biogas may be stored in a similar manner. Instead of a methane-based fuel, for example, the first fuel may be hydrogen or ammonia or a mixture of two or more types of gaseous fuels.

[0037] The engine may further be configured to operate using a second fuel. The second fuel may be either a gaseous fuel or a liquid fuel. If the first fuel is natural gas or biogas, the second fuel may be, for example, hydrogen. Alternatively, the second fuel may be a liquid fuel, such as light fuel oil or heavy fuel oil. The engine may also operate using a third fuel or even more fuels.

[0038] Thus, the engine may be a gas engine, a dual fuel engine or a multi-fuel engine. Thus, the engine is configured to operate using at least one gaseous fuel. In addition, the engine may be configured to operate using one or more additional gaseous fuels and / or one or more liquid fuels.

[0039] The engine can be configured to operate with a mixture of different fuels. For example, the engine can operate with a mixture of hydrogen and some other gaseous fuel and / or a mixture of ammonia and some other gaseous fuel.

[0040] When the engine is operated using gaseous fuel, it can use liquid fuel (such as light fuel oil) as a pilot fuel to promote the ignition of the gaseous fuel. However, this is not necessary, but the gaseous fuel may be self-igniting or a spark plug or other ignition device can be used to ignite the gaseous fuel.

[0041] The cylinder head 1 has a bottom surface 1A and a top surface 1B, the bottom surface 1A being configured to define the upper end of the main combustion chamber 2 of the cylinder 3, and the top surface 1B facing in a direction opposite to the bottom surface 1A. The cylinder 3 of the engine need not be in an upright position, but the cylinder 3 may be tilted from a vertical direction. For example, in a V-type engine, the upper end of the cylinder 3 may be positioned further outward from the longitudinal centerline of the engine than the lower end. Therefore, the term "bottom surface" refers to the side of the cylinder head 1 facing the main combustion chamber 2, but the bottom surface 1A is not necessarily a horizontal surface facing downward.

[0042] The top surface 1B of the cylinder head 1 is configured to receive an intake valve assembly 4 attachable to the cylinder head 1. Thus, the intake valve assembly 4 can be arranged against the top surface 1B of the cylinder head 1 and attached to the cylinder head 1, for example by means of bolts. Figure 2 An attachment hole 27 is shown for attaching the intake valve assembly 4 to the cylinder head 1. The intake valve assembly 4 comprises an intake valve 5 for controlling the supply of gaseous fuel into the cylinder 3. The intake valve 5 is connected to a supply pipe 26 for receiving the gaseous fuel. The supply pipe 26 is a double-walled pipe. The intake valve 5 is a controllable valve that allows the correct amount of gaseous fuel to be introduced into the main combustion chamber 2.

[0043] The cylinder head 1 includes an intake passage 11 for introducing intake air into the main combustion chamber 2 and an air supply passage 12 for introducing gaseous fuel into the intake passage 11, the air supply passage 12 having a first end 12A leading to the top surface 1B of the cylinder head 1 and a second end 12B leading to the intake passage 11 of the cylinder head 1. The cylinder head 1 also includes an exhaust port 25 for exhausting exhaust gas from the main combustion chamber 2. The intake valve assembly 4 is located above the first end 12A of the air supply passage 12 to allow the gaseous fuel to be supplied from the intake valve 5 into the air supply passage 12 and further into the intake passage 11 and the main combustion chamber 2. Because the air supply passage 12 is arranged in the cylinder head 1, a double-walled pipe is not required between the intake valve assembly 4 and the intake passage 11.

[0044] The cylinder head 1 also includes a pre-combustion chamber hole 7. The pre-combustion chamber hole 7 is a cavity formed in the cylinder head 1. In the embodiment of the accompanying drawings, the pre-combustion chamber hole 7 extends from the top surface 1A of the cylinder head 1 to the bottom surface 1B. The pre-combustion chamber hole 7 is configured to receive and / or form a pre-combustion chamber assembly, which includes a pre-combustion chamber 9 and a pre-combustion chamber injector 10, and the pre-combustion chamber injector 10 is configured to introduce gaseous fuel into the pre-combustion chamber 9. In the embodiment of the accompanying drawings, the pre-combustion chamber assembly protrudes into the main combustion chamber 2. The pre-combustion chamber assembly can be made of several parts. The pre-combustion chamber 9 is in fluid communication with the main combustion chamber 2. Therefore, gas can flow from the pre-combustion chamber 9 into the main combustion chamber 2 and from the main combustion chamber 2 into the pre-combustion chamber 9.

[0045] The cylinder head 1 further comprises holes 28 for receiving intake valves and holes 29 for receiving exhaust valves.

[0046] The cylinder head 1 includes at least one auxiliary passage 13, 14 having a first end 13A, 14A opening to the top surface 1B of the cylinder head 1 and a second end 13B, 14B opening to the pre-combustion chamber hole 7. The first end 13A, 14A of the auxiliary passage 13, 14 is located in a region configured to be covered by the intake valve assembly 4 in the installed state of the cylinder head assembly including the cylinder head 1 and the intake valve assembly 4.

[0047] The auxiliary passages 13, 14 allow gaseous fuel to flow between the pre-chamber bore 7 and the top surface 1B of the cylinder head 1. Flow from the intake valve assembly 4 to the pre-chamber assembly and / or flow in the reverse direction is thus permitted. This reduces the need for double walled pipes in the fuel supply system of the engine and reduces the number of possible gas leak locations.

[0048] In the embodiment of the drawings, the cylinder head 1 includes a first auxiliary passage 13 and a second auxiliary passage 14. Each of the auxiliary passages 13, 14 has a first end 13A, 14A and a second end 13B, 14B as described above. However, the cylinder head 1 may be provided with only one of the auxiliary passages 13, 14.

[0049] In the embodiment of the accompanying drawings, the first auxiliary channel 13 is a pre-combustion chamber air supply channel 13, and the second end 13B of the first auxiliary channel 13 is arranged at a position that allows connection to a pre-combustion chamber injector 10 for introducing gaseous fuel into the pre-combustion chamber 9. The main part of the gaseous fuel introduced into the cylinder 3 is introduced into the intake passage 11 via the air supply passage 12 and further introduced into the main combustion chamber 2. The gaseous fuel introduced into the intake passage 11 flows into the main combustion chamber 2 during the intake stroke. The fuel introduced into the intake passage 11 can form a lean mixture with the intake air. A portion of the gaseous fuel is introduced into the pre-combustion chamber 9. This allows a richer mixture to be formed in the pre-combustion chamber 9. The richer fuel / air mixture can be ignited in the pre-combustion chamber 9, for example, by a spark plug. The combustion of the richer mixture promotes the ignition of the leaner mixture in the main combustion chamber 2.

[0050] In the embodiment of the accompanying drawings, the second auxiliary channel 14 is a pre-combustion chamber gas leakage detection channel 14, and the second end 14B of the second auxiliary channel 14 is arranged at a position that allows the gas fuel that may leak to be discharged from the pre-combustion chamber hole 7. If a gas leak occurs in the pre-combustion chamber assembly, the leaked fuel can be guided to the intake valve assembly 4 via the second auxiliary channel 14. The leaked fuel can be further guided from the intake valve assembly 4 to the leak detector. Alternatively, the intake valve assembly can be provided with a leak detector. The leak detector can be a gas detector. The gas detector is configured to detect the presence of a certain gas. Alternatively, the leak detector can be a pressure sensor. The leaked fuel can be guided into a closed volume or a volume where the gas outflow is restricted, and the pressure sensor can be arranged to monitor the pressure in the volume, thereby detecting the presence of the leaked fuel.

[0051] The same leak detector may be configured to also detect leaks elsewhere in the fuel supply system. For example, a leak from the air supply pipe 26 may be directed in the outer tube of the air supply pipe 26 to the same leak detector as a leak from the pre-combustion chamber assembly. The outer tube of the air supply pipe 26 may be used to direct a leak from the pre-combustion chamber assembly to a leak detector.

[0052] In the embodiment of the drawings, the intake valve assembly 4 has an inner wall surface 15 and an outer wall surface 16. The inner wall surface 15 surrounds the first end 12A of the air supply passage 12. The outer wall surface 16 is arranged radially outside the inner wall surface 15. In the embodiment of the drawings, the first end 13A, 14A of each of the auxiliary passages 13, 14 is located at a distance from the first end 12A of the air supply passage 12, so that when the intake valve assembly 4 is attached to the cylinder head 1, the first ends 13A, 14A of the auxiliary passages 13, 14 open to the area between the inner wall surface 15 and the outer wall surface 16.

[0053] In the embodiment of the accompanying drawings, the top surface 1B of the cylinder head 1 is provided with an inner sealing groove 17 and an outer sealing groove 18 around the first end 12A of the air supply passage 12. Each of the sealing grooves 17, 18 is configured to receive a sealing element 19, 20. For example, the sealing element may be an O-ring. The first end 13A, 14A of each of the auxiliary passages 13, 14 is located between the inner sealing groove 17 and the outer sealing groove 18. Therefore, the sealing element 19 arranged in the inner sealing groove 17 forms a seal between the first end 12A of the air supply passage 12 and the first end 13A, 14A of each of the first auxiliary passage 13 and the second auxiliary passage 14. The sealing element 20 arranged in the outer sealing groove 18 forms a seal that prevents radial leakage from the auxiliary passages 13, 14 to the outside.

[0054] In the embodiment of the drawings, the top surface 1B of the cylinder head 1 is provided with a sealing groove 21 arranged around the first end 13A of the first auxiliary channel 13A. The sealing groove 21 of the first auxiliary channel 13 is located between the inner sealing groove 17 and the outer sealing groove 18. The sealing groove 21 is configured to receive a sealing element 22. For example, the sealing element 22 may be an O-ring.

[0055] The cylinder head 1 and the intake valve assembly 4 arranged on the top surface of the cylinder head 1 form a cylinder head assembly. In the embodiment of the drawings, the intake valve assembly 4 includes a connection block 6 for attaching the intake valve 5 to the cylinder head 1. The connection block 6 is arranged against the top surface 1B of the cylinder head 1, and the inner wall surface 15 around the first end 12A of the air supply passage 12 and the outer wall surface 16 around the first end 12A of the air supply passage 12 are part of the connection block 6.

[0056] The connecting block 6 is configured to receive the intake valve 5. In the installed state of the intake valve 5, a gas supply space 24 is formed between the connecting block 6 and the intake valve 5. The connecting block includes a gas channel 23, which is configured to be connected to the first end 13A of the first auxiliary channel 13 of the cylinder head 1. The gas channel 23 is configured to connect the gas supply space 24 to the first auxiliary channel 13. From the gas supply pipe 26, gas fuel is delivered to the intake valve 5 and enters the gas supply space 24. From the gas supply space 24, the fuel can flow into the first auxiliary channel 13 via the gas channel 23 and further flow to the pre-combustion chamber injector 10. The pre-combustion chamber injector 10 can be used to inject fuel into the pre-combustion chamber 9.

[0057] The connection block 6 comprises a gas leakage channel, which is connected to the second auxiliary channel 14 in the installed state of the connection block 6. Via the second auxiliary channel 14, the leaking fuel can be guided from the pre-chamber hole 7 to the connection block 6. The leaking fuel can be guided into the outer tube of the gas supply pipe 26 and further guided to a leak detector, such as a gas detector or a pressure sensor. Therefore, the same leak detector can be configured to monitor the space between the inner tube and the outer tube of the gas supply pipe 26 and the pre-chamber assembly. The connection block 6 can be configured to include a hole, which is configured to receive the leak detector. The same leak detector can be arranged to monitor the leakage of the pre-chamber assembly and the gas supply pipe 26.

[0058] It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may be varied within the scope of the appended claims.

Claims

1. A cylinder head (1) for a piston engine, the cylinder head (1) having a bottom surface (1A) and a top surface (1B), the bottom surface (1A) being configured to define an upper end of a main combustion chamber (2) of a cylinder (3) of the piston engine, the top surface (1B) facing in a direction opposite to the bottom surface (1A), the top surface (1B) being configured to receive an intake valve assembly (4) that can be attached to the cylinder head (1), the cylinder head (1) comprising: - pre-chamber hole (7); - an intake duct (11) for introducing intake air into the main combustion chamber (2); as well as - an air supply passage (12) for introducing gaseous fuel into the intake passage (11), the air supply passage (12) having a first end (12A) opening to the top surface (1B) of the cylinder head (1) and a second end opening to the intake passage (11) of the cylinder head (1), It is characterized in that the cylinder head (1) includes an auxiliary channel (13, 14), the auxiliary channel (13, 14) having a first end (13A, 14A) leading to the top surface (1B) of the cylinder head (1) and a second end (13B, 14B) leading to the pre-combustion chamber hole (7), wherein the first end (13A, 14A) of the auxiliary channel (13, 14) is located in an area configured to be covered by the intake valve assembly (4).

2. The cylinder head (1) according to claim 1, wherein: The first ends (13A, 14A) of the auxiliary passages (13, 14) are positioned at a distance from the first end (12A) of the air supply passage (12) so that when the intake valve assembly (4) is attached to the cylinder head (1), the first ends (13A, 14A) of the auxiliary passages (13, 14) open into a region between an inner wall surface (15) and an outer wall surface (16) of the intake valve assembly (4).

3. The cylinder head (1) according to claim 1 or 2, wherein: The top surface (1B) of the cylinder head (1) is provided with an inner sealing groove (17) and an outer sealing groove (18) around the first end (12A) of the air supply passage (12), each sealing groove (17, 18) being configured to receive a sealing element (19, 20), and the first end (13A, 14A) of the auxiliary passage (13, 14) is located between the inner sealing groove (17) and the outer sealing groove (18).

4. The cylinder head (1) according to any one of claims 1 to 3, wherein: The top surface (1B) of the cylinder head (1) is provided with a sealing groove (21) arranged around the first end (13A, 14A) of the auxiliary channel (13A).

5. Cylinder head (1) according to any one of the preceding claims, wherein: The auxiliary passages (13, 14) are pre-combustion chamber air supply passages (13), and the second end (13B) of the auxiliary passages (13) is arranged at a position allowing connection to a pre-combustion chamber injector (10), the pre-combustion chamber injector (10) being used to introduce the gas fuel into the pre-combustion chamber (9).

6. The cylinder head (1) according to any one of claims 1 to 4, wherein: The auxiliary passage (13, 14) is a pre-combustion chamber gas leakage detection passage (14), and the second end (14B) of the auxiliary passage (14) is arranged at a position allowing possible leaked gas fuel to be discharged from the pre-combustion chamber hole (7).

7. The cylinder head (1) according to claim 5, wherein: The cylinder head (1) also includes a second auxiliary channel (14), which is a pre-combustion chamber gas leakage detection channel, and the second auxiliary channel (14) has a first end (14A) leading to the top surface (1B) of the cylinder head (1) and a second end (14B) leading to the pre-combustion chamber hole (7), wherein the first end (14A) of the second auxiliary channel (14) is located in the area configured to be covered by the intake valve assembly (4), and the second end (14B) of the second auxiliary channel (14) is arranged at a position allowing possible leaked gas fuel to be discharged from the pre-combustion chamber hole (7).

8. A cylinder head assembly for a piston engine, comprising a cylinder head (1) according to any one of the preceding claims and an intake valve assembly (4) arranged on a top surface (1B) of the cylinder head (1).

9. The cylinder head assembly according to claim 8, wherein: The intake valve assembly (4) comprises a connection block (6) for attaching the intake valve (4) to the cylinder head (1), wherein the connection block (6) is arranged against a top surface (1B) of the cylinder head (1) and comprises an inner wall surface (15) surrounding a first end (12A) of the air supply passage (12) and an outer wall surface (16) surrounding the first end (12A) of the air supply passage (12).

10. The cylinder head assembly according to claim 8 or 9, wherein: The auxiliary passage (13, 14) is configured to connect the pre-chamber hole (7) to the intake valve assembly (4) between an inner wall surface (15) and an outer wall surface (16) of the intake valve assembly (4).

11. A piston engine comprising a cylinder head assembly according to any one of claims 8 to 10.

12. A connection block (6) for attaching an intake valve (4) to an upper surface (1B) of a cylinder head (1) according to any one of claims 1 to 8, wherein: The connection block (6) is configured to receive an intake valve (4) and includes a gas passage (23) configured to be connected to a first end (13A, 14A) of an auxiliary passage (13, 14) of the cylinder head (1).

13. The connection block (6) according to claim 12, wherein: The gas passage (23) is configured to be connected to a gas supply space (24) formed between the connection block (6) and the intake valve (4) when the intake valve (4) is installed.

14. The connection block (6) according to claim 12, wherein: The gas passage (23) is configured to connect the auxiliary passage (14) of the cylinder head (1) to a leak detector.

15. The connection block (6) according to any one of claims 12 to 14, for attaching an intake valve (4) to an upper surface (1B) of a cylinder head (1) according to claim 7, wherein: The connection block (6) includes a second gas passage configured to be connected to a first end (14A) of a second auxiliary passage (14) of the cylinder head (1).

16. A method of detecting a gaseous fuel leak in a piston engine, the method comprising: - introducing intake air into the main combustion chamber (2) of the cylinder (3) via an intake duct (11) located in the cylinder head (1) of the cylinder (3) of the engine; - introducing gaseous fuel from an intake valve assembly (4) attached to the cylinder head (1) into the intake passage (11) through an intake passage (12), the intake passage (12) being arranged in the cylinder head (1) and having a first end (12A) opening to a top surface (1B) of the cylinder head (1) and a second end opening to the intake passage (11), Characterized in that the method comprises: - directing possible leaking fuel from the pre-combustion chamber assembly (10) via auxiliary channels (13, 14) to the intake valve assembly (4) and further to a leak detector; and - Using the leak detector to detect the gaseous fuel guided via the auxiliary passage (13, 14).

17. The method according to claim 16, wherein: The leak detector is a gas detector or a pressure sensor.

18. The method according to claim 16 or 17, wherein: The leak detector is used to monitor a possible gas leak in a gas supply pipe (26) that supplies gas fuel to the intake valve assembly (4).

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