WO2024033562A1 - Cylinder head, cylinder head assembly, piston engine, connecting block and method of detecting leakages of gaseous fuel in a piston engine - Google Patents

Cylinder head, cylinder head assembly, piston engine, connecting block and method of detecting leakages of gaseous fuel in a piston engine Download PDF

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Publication number
WO2024033562A1
WO2024033562A1 PCT/FI2022/050525 FI2022050525W WO2024033562A1 WO 2024033562 A1 WO2024033562 A1 WO 2024033562A1 FI 2022050525 W FI2022050525 W FI 2022050525W WO 2024033562 A1 WO2024033562 A1 WO 2024033562A1
Authority
WO
WIPO (PCT)
Prior art keywords
cylinder head
gas
channel
admission valve
prechamber
Prior art date
Application number
PCT/FI2022/050525
Other languages
French (fr)
Inventor
Ari-Matti OJANPERÄ
Ilari AHLVIK
Jouni HAKALAHTI
Katri MÄKINEN
Original Assignee
Wärtsilä Finland Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wärtsilä Finland Oy filed Critical Wärtsilä Finland Oy
Priority to PCT/FI2022/050525 priority Critical patent/WO2024033562A1/en
Publication of WO2024033562A1 publication Critical patent/WO2024033562A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
    • F02B19/1019—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber
    • F02B19/108—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber with fuel injection at least into pre-combustion chamber, i.e. injector mounted directly in the pre-combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0281—Adapters, sockets or the like to mount injection valves onto engines; Fuel guiding passages between injectors and the air intake system or the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0293—Safety devices; Fail-safe measures

Definitions

  • the present invention relates to a cylinder head for a piston engine, as defined in the preamble of claim 1.
  • the invention also concerns a cylinder head assembly for a piston engine and a piston engine.
  • the invention further concerns a connecting block for attaching a gas admission valve to a cylinder head and a method of detecting leakages of gaseous fuel in a piston engine.
  • each cylinder of the engine is provided with an own cylinder head.
  • the cylinder head closes the upper end of the cylinder and delimits a main combustion chamber.
  • the cylinder head serves for several purposes.
  • the cylinder head is provided with an inlet port for introducing intake air into the combustion chamber and with an exhaust port for discharging exhaust gas from the combustion chamber.
  • Intake and exhaust valves are arranged in the cylinder head.
  • gas engines or dual- or multi-fuel engines operable using gaseous fuels are often provided with a prechamber.
  • Engines are often operated in a gas mode using a lean air-fuel mixture, and a prechamber allows forming a richer mixture in the prechamber and thus facilitating the ignition of the lean mixture in the main combustion chamber.
  • a major part of the prechamber is arranged within the cylinder head.
  • a double-wall pipe comprises an inner pipe, in which the fuel is conducted, and an outer pipe forming a protective sheath around the inner pipe. If there is a leakage in the inner pipe, the leaking fuel is captured by the outer pipe.
  • the space between the inner pipe and the outer pipe is typically ventilated to a safe place. In addition, the space can be monitored by a gas detector and an alarm is triggered if gas leakage is detected.
  • An object of the invention is to provide an improved cylinder head for a piston engine.
  • the characterizing features of the cylinder head according to the invention are listed in the characterizing part of claim 1.
  • Another object of the invention is to provide an improved cylinder head assembly.
  • a further object of the invention is to provide an improved piston engine.
  • Further objects of the invention are to provide a connecting block for attaching a gas admission valve to the upper surface of a cylinder head and a method for detecting leakages of gaseous fuel in a piston engine.
  • the cylinder head according to the invention has a bottom surface configured to delimit an upper end of a main combustion chamber of a cylinder of a piston engine, and a top surface facing an opposite direction than the bottom surface, the top surface being configured to receive a gas admission valve assembly that is attachable to the cylinder head.
  • the cylinder head comprises a prechamber hole, an inlet port for introducing intake air into the main combustion chamber, and a gas supply channel having a first end that opens onto the top surface of the cylinder head and a second end that opens into the inlet port of the cylinder head for introducing gaseous fuel from the gas admission valve into the inlet port.
  • the cylinder head further comprises an auxiliary channel having a first end that opens onto the top surface of the cylinder head and a second end that opens into the prechamber hole, wherein the first end of the auxiliary channel is located in an area that is configured to be covered by the gas admission valve assembly.
  • the auxiliary channel can be used for conveying gaseous fuel to be injected or it can be used as a leak channel for possibly leaking gaseous fuel.
  • the channel located within the cylinder head does not need to be a double-wall pipe. Because of the auxiliary channel opening onto an area configured to be covered by the gas admission valve assembly, the number of components in the gas supply system can be reduced. This makes the system less complex and reduces the number of potential gas leakage locations.
  • the first end of the auxiliary channel is located at such a distance from the first end of the gas supply channel that when a gas admission valve assembly is attached to the cylinder head, the first end of the auxiliary channel opens into an area between an inner wall surface and an outer wall surface of the gas admission valve assembly.
  • the gas admission valve assembly can thus be provided with a connection point for the auxiliary channel between the inner wall surface and the outer wall surface.
  • the top surface of the cylinder head is provided around the first end of the gas supply channel with an inner sealing groove and an outer sealing groove, each sealing groove being configured to receive a sealing element, and the first end of the auxiliary channel is located between the inner sealing groove and the outer sealing groove. This allows effective sealing of the auxiliary channel both outwards and towards the gas supply channel.
  • the top surface of the cylinder head is provided with a sealing groove arranged around the first end of the auxiliary channel. This allows effective sealing of the joint between the end of the auxiliary channel and the gas admission valve assembly.
  • the auxiliary channel is a prechamber gas supply channel, and the second end of the auxiliary channel is arranged at a location allowing connection to a prechamber injector for introducing the gaseous fuel into the prechamber.
  • the auxiliary channel is a prechambergas leak detection channel, and the second end of the auxiliary channel is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole. This allows using the same leak detector to detect gaseous fuel leaking both from the prechamber injector and from elsewhere of the fuel supply system.
  • the cylinder head further comprises a first auxiliary channel, which a prechamber gas supply channel, and a second auxiliary channel, which is a prechamber gas leak detection channel.
  • the cylinder head assembly comprises a cylinder head defined above and a gas admission valve assembly arranged on the top surface of the cylinder head.
  • the gas admission valve assembly comprises a connecting block for attaching the gas admission valve to the cylinder head, wherein the connecting block is arranged against the top surface of the cylinder head and comprises an inner wall surface surrounding the first end of the gas supply channel and an outer wall surface surrounding the first end of the gas supply channel.
  • the area between the inner wall surface and the outer wall surface can be used for providing connections for one or more auxiliary channels.
  • the auxiliary channel is configured to connect the prechamber hole to the gas admission valve assembly between an inner wall surface and an outer wall surface of the gas admission valve assembly. This allows connecting the auxiliary channel to a leak detector.
  • the piston engine according to the invention comprises a cylinder head assembly defined above.
  • the connecting block according to the invention for attaching a gas admission valve to the upper surface of a cylinder head defined above is configured to receive a gas admission valve and comprises a gas channel that is configured to connect to the first end of the auxiliary channel of the cylinder head.
  • the gas channel is configured to connect to a gas supply space forming between the connecting block and the gas admission valve in a mounted state of the gas admission valve. This allows gas supply through the auxiliary channel.
  • the gas channel is configured to connect an auxiliary channel of the cylinder head to a leak detector. This allows the use of the auxiliary channel as a gas leak detection channel.
  • the connecting block comprises a first gas channel configured to connect to the first end of a first auxiliary channel of the cylinder head and a second gas channel configured to connect to the first end of a second auxiliary channel of the cylinder head.
  • the gas channels of the connecting block can thus connect to both a prechamber gas supply channel and a prechamber gas leak detection channel.
  • the method according to the invention for detecting leakages of gaseous fuel in a piston engine comprises the steps of introducing intake air into a main combustion chamber of a cylinder of the engine via an inlet port located in the cylinder head of said cylinder, introducing gaseous fuel from a gas admission valve assembly attached to the cylinder head into the inlet port through a gas supply channel arranged in the cylinder head and having a first end that opens onto a top surface of the cylinder head and a second end that opens into the inlet port, conducting possibly leaking fuel from a prechamber assembly via an auxiliary channel to the gas admission valve assembly and further to a leak detector, and using said leak detector to detect gaseous fuel conducted via the auxiliary channel.
  • the auxiliary channel is thus used as a leak channel conducting possibly leaking fuel to a leak detector. This reduces the number of joints in the fuel supply system of the engine.
  • the leak detector is a gas detector or a pressure sensor.
  • said leak detector is used for monitoring possible gas leakages of a gas supply pipe supplying gaseous fuel to the gas admission valve assembly.
  • the same leak detector is thus used for detecting gas leakages from both the prechamber assembly and the gas supply Pipe.
  • Fig. 1 shows a perspective view of a cylinder head according to an embodiment of the invention
  • Fig. 2 shows an enlarged view of detail E of figure 1 ,
  • Fig. 3 shows a cross-sectional view of a cylinder head assembly according to an embodiment of the invention
  • Fig. 4 shows another cross-sectional view of the cylinder head assembly of figure 3.
  • Figure 1 shows a cylinder head 1 according to an embodiment of the invention.
  • the cylinder head 1 is a cylinder head of a large piston engine.
  • the expression “large piston engine” refers here to an engine having a cylinder diameter of at least 150 mm.
  • the engine can be, for instance, an engine that is used as a main or an auxiliary engine in a ship or an engine that is used at a power plant for driving a generator for producing electricity.
  • the engine is a four-stroke engine.
  • Figures 3 and 4 show schematically an 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 an own cylinder head 1 .
  • the cylinder head 1 can be a one-piece part.
  • the engine in which the cylinder head 1 is used is configured to be operable using at least a first, gaseous fuel.
  • gaseous fuel refers here to a fuel that is gaseous in atmospheric pressure and at a temperature of 20 °C.
  • the first fuel can be, for instance, natural gas or biogas.
  • biogas refers here to a gas that mainly consists of methane and which is obtained from renewable sources. The biogas can be produced for example from organic waste. Natural gas could be stored either as a liquefied gas (LNG) or compressed gas (CNG). Biogas could be stored in a similar manner.
  • the first fuel could be, for instance, hydrogen or ammonia or a mixture of two or more types of gaseous fuel.
  • the engine can be further configured to be operable using a second fuel.
  • the second fuel can be either gaseous fuel or liquid fuel. If the first fuel is natural gas or biogas, the second fuel could be, for instance, hydrogen. Alternatively, the second fuel could be liquid fuel, such as light fuel oil or heavy fuel oil.
  • the engine can also be operable using a third fuel or even further fuels.
  • the engine can thus be a gas engine, a dual-fuel engine or a multi-fuel engine.
  • the engine is thus configured to be operable using at least one gaseous fuel.
  • the engine can be configured to be operable using one or more additional gaseous fuels, and/or one or more liquid fuels.
  • the engine can be configured to be operable using mixtures of different fuels.
  • the engine could be operable using a mixture of hydrogen and some other gaseous fuel and/or a mixture of ammonia and some other gaseous fuel.
  • the engine When the engine is operated using a gaseous fuel, it can utilize a liquid fuel, such as light fuel oil as a pilot fuel facilitating ignition of the gaseous fuel.
  • a liquid fuel such as light fuel oil
  • the gaseous fuel could be self-igniting or spark plugs or other ignition means could be used for igniting the gaseous fuel.
  • the cylinder head 1 has a bottom surface 1A configured to delimit an upper end of a main combustion chamber 2 of a cylinder 3, and a top surface 1 B facing an opposite direction than the bottom surface 1A.
  • the cylinders 3 of the engine do not need to be in an upright position, but the cylinders 3 can be inclined from the vertical direction. For instance in a V-engine, the upper ends of the cylinders 3 can be located farther outwards from the longitudinal center line of the engine than the lower ends.
  • the term “bottom surface” thus refers to that side of the cylinder head 1 that is facing the main combustion chamber 2, but the bottom surface 1A does not need to be a horizontal surface facing downwards.
  • the top surface 1 B of the cylinder head 1 is configured to receive a gas admission valve assembly 4 that is attachable to the cylinder head 1.
  • the gas admission valve assembly 4 can thus be arranged against the top surface 1 B of the cylinder head 1 and attached to the cylinder head 1 , for example by means of bolts.
  • Figure 2 shows attachment holes 27 for attaching the gas admission valve assembly 4 to the cylinder head 1.
  • the gas admission valve assembly 4 comprises a gas admission valve 5 for controlling supply of gaseous fuel into the cylinder 3.
  • the gas admission valve 5 is connected to a gas supply pipe 26 for receiving the gaseous fuel.
  • the gas supply pipe 26 is a double-wall pipe.
  • the gas admission valve 5 is a controllable valve allowing introducing the correct amount of gaseous fuel into the main combustion chamber 2.
  • the cylinder head 1 comprises an inlet port 11 for introducing intake air into the main combustion chamber 2, and a gas supply channel 12 having a first end 12A that opens onto the top surface 1 B of the cylinder head 1 and a second end 12B that opens into the inlet port 11 of the cylinder head 1 for introducing gaseous fuel into the inlet port 11 .
  • the cylinder head 1 also comprises an exhaust port 25 for discharging exhaust gas from the main combustion chamber 2.
  • the gas admission valve assembly 4 is located above the first end 12A of the gas supply channel 12 to allow supply of gaseous fuel from the gas admission valve 5 into the gas supply channel 12 and further into the inlet port 11 and the main combustion chamber 2. Because the gas supply channel 12 is arranged within the cylinder head 1 , a double-wall pipe is not needed between the gas admission valve assembly 4 and the inlet port 11 .
  • the cylinder head 1 further comprises a prechamber hole 7.
  • the prechamber hole 7 is a cavity formed within the cylinder head 1 .
  • the prechamber hole 7 extends from the top surface 1A to the bottom surface 1 B of the cylinder head 1.
  • the prechamber hole 7 is configured to receive and/or form a prechamber assembly comprising a prechamber 9 and a prechamber injector 10 configured to introduce gaseous fuel into the prechamber 9.
  • the prechamber assembly protrudes into the main combustion chamber 2.
  • the prechamber assembly can be made of several parts.
  • the prechamber 9 is in fluid communication with the main combustion chamber 2. Gases can thus flow from the prechamber 9 into the main combustion chamber 2 and from the main combustion chamber 2 into the prechamber 9.
  • the cylinder head 1 also comprises holes 28 for receiving intake valves and holes 29 for receiving exhaust valves.
  • the cylinder head 1 comprises at least one auxiliary channel 13, 14 having a first end 13A, 14A that opens onto the top surface 1 B of the cylinder head 1 and a second end 13B, 14B that opens into the prechamber hole 7.
  • the first end 13A, 14A of the auxiliary channel 13, 14 is located in an area that is configured to be covered by the gas admission valve assembly 4 in a mounted state of a cylinder head assembly comprising the cylinder head 1 and the gas admission valve assembly 4.
  • the auxiliary channels 13, 14 allow flow of gaseous fuel between the prechamber hole 7 and the top surface 1 B of the cylinder head 1 . Flow from the gas admission valve assembly 4 to the prechamber assembly and/or in the opposite direction is thus allowed. This reduces the need of double-wall pipes in the fuel supply system of the engine and reduces the number of potential gas leakage locations.
  • the cylinder head 1 comprises a first auxiliary channel 13 and a second auxiliary channel 14.
  • Each of the auxiliary channels 13, 14 has a first end 13A, 14A and a second end 13B, 14B as described above.
  • the cylinder head 1 could be provided with only one of the auxiliary channels 13, 14.
  • the first auxiliary channel 13 is a prechamber gas supply channel 13, and the second end 13B of the first auxiliary channel 13 is arranged at a location allowing connection to a prechamber injector 10 for introducing the gaseous fuel into the prechamber 9.
  • Main part of the gaseous fuel introduced into the cylinder 3 is introduced via the gas supply channel 12 into the inlet port 11 and further into the main combustion chamber 2.
  • the gaseous fuel introduced into the inlet port 11 flows during the intake stroke into the main combustion chamber 2.
  • the fuel introduced into the inlet port 11 can form a lean mixture with the intake air.
  • Part of the gaseous fuel is introduced into the prechamber 9. This allows forming a richer mixture in the prechamber 9.
  • the richer fuel/air mixture can be ignited in the prechamber 9, for instance by means of a spark plug.
  • the combustion of the richer mixture facilitates the ignition of the leaner mixture in the main combustion chamber 2.
  • the second auxiliary channel 14 is a prechambergas leak detection channel 14, and the second end 14B of the second auxiliary channel 14 is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole 7.
  • the leaking fuel can be conducted via the second auxiliary channel 14 to the gas admission valve assembly 4.
  • the gas admission valve assembly can be provided with a leak detector.
  • the leak detector can be a gas detector.
  • a gas detector is configured to detect the presence of a certain gas.
  • the leak detector could be a pressure sensor. Leaking fuel can be conducted into a closed volume or into a volume where the outflow of gases is restricted, and the pressure sensor can be arranged to monitor the pressure in said volume, thus detecting the presence of leaking fuel.
  • the same leak detector can be configured to detect leakages also elsewhere in the fuel supply system. For instance, leakages of the gas supply pipe 26 can be conducted in an outer pipe of the gas supply pipe 26 to the same leak detector as the leakages from the prechamber assembly. The outer pipe of the gas supply pipe 26 can be used for conducting leakage from the prechamber assembly to the leak detector.
  • the gas admission 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 gas supply channel 12.
  • the outer wall surface 16 is arranged radially outwards from the inner wall surface 15.
  • the first end 13A, 14A of each of the auxiliary channels 13, 14 is located at such a distance from the first end 12A of the gas supply channel 12 that when a gas admission valve assembly 4 is attached to the cylinder head 1 , the first end 13A, 14A of the auxiliary channel 13, 14 opens into an area between the inner wall surface 15 and the outer wall surface 16.
  • the top surface 1 B of the cylinder head 1 is provided around the first end 12A of the gas supply channel 12 with an inner sealing groove 17 and an outer sealing groove 18.
  • Each of the sealing grooves 17, 18 is configured to receive a sealing element 19, 20.
  • the sealing element can be, for instance, an O-ring.
  • the first end 13A, 14A of each of the auxiliary channels 13, 14 is located between the inner sealing groove 17 and the outer sealing groove 18.
  • the sealing element 19 arranged in the inner sealing groove 17 thus forms a seal between the first end 12A of the gas supply channel 12 and the first end 13A, 14A of each of the first auxil iary channel 13 and the second auxiliary channel 14.
  • the sealing element 20 arranged in the outer sealing groove 18 forms a seal preventing leakages from the auxiliary channels 13,14 radially outwards.
  • the top surface 1 B 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.
  • the sealing element 22 can be, for instance, an O-ring.
  • the cylinder head 1 and the gas admission valve assembly 4 arranged on the top surface of the cylinder head 1 form a cylinder head assembly.
  • the gas admission valve assembly 4 comprises a connecting block 6 for attaching the gas admission valve 5 to the cylinder head 1 .
  • the connecting block 6 is arranged against the top surface 1 B of the cylinder head 1 and the inner wall surface 15 surrounding the first end 12A of the gas supply channel 12 and the outer wall surface 16 surrounding the first end 12A of the gas supply channel 12 are part of the connecting block 6.
  • the connecting block 6 is configured to receive the gas admission valve 5. In a mounted state of the gas admission valve 5, a gas supply space 24 is formed between the connecting block 6 and the gas admission valve 5.
  • the connecting block comprises a gas channel 23 that is configured to connect to the first end 13A of the first the 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.
  • gaseous fuel is conveyed to the gas admission valve 5 and into the gas supply space 24.
  • the fuel can flow via the gas channel 23 into the first auxiliary channel 13 and further to the prechamber injector 10.
  • the prechamber injector 10 can be used for injecting the fuel into the prechamber 9.
  • the connecting block 6 comprises a gas leakage channel that is in the mounted state of the connecting block 6 connected to the second auxiliary channel 14. Via the second auxiliary channel 14, leaking fuel can be conducted from the prechamber hole 7 to the connecting block 6. The leaking fuel can be conducted into the outer pipe of the gas supply pipe 26 and further to a leak detector, such as a gas detector or pressure sensor. The same leak detector can thus be configured to monitor the space between the inner pipe and the outer pipe of the gas supply pipe 26 and the prechamber assembly.
  • the connecting block 6 could be configured to comprise a hole that is configured to receive a leak detector. The same leak detector could be arranged to monitor leakages of the prechamber assembly and the gas supply pipe 26. It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
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Abstract

The cylinder head (1) for a piston engine has a bottom surface (1A) configured to delimit a main combustion chamber (2) and a top surface (1B) facing an opposite direction and configured to receive a gas admission valve assembly (4) attachable to the cylinder head (1), the cylinder head (1) comprising a pre-chamber hole (7), an inlet port (11) for introducing intake air into the main combustion chamber (2), and a gas supply chan-nel (12) having a first end (12A) opening onto the top surface (1B) and a second end opening into the inlet port (11) for in-troducing gaseous fuel into the inlet port (11). The cylinder head (1) further comprises an auxiliary channel (13, 14) hav-ing a first end (13A, 14A) opening onto the top surface (1B) and a second end (13B, 14B) opening into the prechamber hole (7), the first end (13A, 14A) being located in an area con-figured to be covered by the gas admission valve assembly (4).

Description

Cylinder head, cylinder head assembly, piston engine, connecting block and method of detecting leakages of gaseous fuel in a piston engine
Technical field of the invention
The present invention relates to a cylinder head for a piston engine, as defined in the preamble of claim 1. The invention also concerns a cylinder head assembly for a piston engine and a piston engine. The invention further concerns a connecting block for attaching a gas admission valve to a cylinder head and a method of detecting leakages of gaseous fuel in a piston engine.
Background of the invention
In large piston engines, such as in engines used as main or auxiliary engines in ships or in engines used at powerplants for producing electricity, each cylinder of the engine is provided with an own cylinder head. The cylinder head closes the upper end of the cylinder and delimits a main combustion chamber. In four-stroke engines, the cylinder head serves for several purposes. For instance, the cylinder head is provided with an inlet port for introducing intake air into the combustion chamber and with an exhaust port for discharging exhaust gas from the combustion chamber. Intake and exhaust valves are arranged in the cylinder head. Especially gas engines or dual- or multi-fuel engines operable using gaseous fuels are often provided with a prechamber. Engines are often operated in a gas mode using a lean air-fuel mixture, and a prechamber allows forming a richer mixture in the prechamber and thus facilitating the ignition of the lean mixture in the main combustion chamber. A major part of the prechamber is arranged within the cylinder head.
The use of gaseous fuels brings many benefits, such as reduced emissions. However, leaking gaseous fuel poses a safety risk, and therefore certain protective measures are needed in engines that are operable using gaseous fuels. Especially in marine applications, classification societies set strict safety requirements. One of the requirements set for gas engines is that in most cases gaseous fuels need to be conducted in double-wall pipes. A double-wall pipe comprises an inner pipe, in which the fuel is conducted, and an outer pipe forming a protective sheath around the inner pipe. If there is a leakage in the inner pipe, the leaking fuel is captured by the outer pipe. The space between the inner pipe and the outer pipe is typically ventilated to a safe place. In addition, the space can be monitored by a gas detector and an alarm is triggered if gas leakage is detected.
The need of double-walled pipes and gas detectors make gas engines more complicated and expensive.
Summary of the invention
An object of the invention is to provide an improved cylinder head for a piston engine. The characterizing features of the cylinder head according to the invention are listed in the characterizing part of claim 1. Another object of the invention is to provide an improved cylinder head assembly. A further object of the invention is to provide an improved piston engine. Further objects of the invention are to provide a connecting block for attaching a gas admission valve to the upper surface of a cylinder head and a method for detecting leakages of gaseous fuel in a piston engine.
The cylinder head according to the invention has a bottom surface configured to delimit an upper end of a main combustion chamber of a cylinder of a piston engine, and a top surface facing an opposite direction than the bottom surface, the top surface being configured to receive a gas admission valve assembly that is attachable to the cylinder head. The cylinder head comprises a prechamber hole, an inlet port for introducing intake air into the main combustion chamber, and a gas supply channel having a first end that opens onto the top surface of the cylinder head and a second end that opens into the inlet port of the cylinder head for introducing gaseous fuel from the gas admission valve into the inlet port. The cylinder head further comprises an auxiliary channel having a first end that opens onto the top surface of the cylinder head and a second end that opens into the prechamber hole, wherein the first end of the auxiliary channel is located in an area that is configured to be covered by the gas admission valve assembly.
The auxiliary channel can be used for conveying gaseous fuel to be injected or it can be used as a leak channel for possibly leaking gaseous fuel. The channel located within the cylinder head does not need to be a double-wall pipe. Because of the auxiliary channel opening onto an area configured to be covered by the gas admission valve assembly, the number of components in the gas supply system can be reduced. This makes the system less complex and reduces the number of potential gas leakage locations.
According to an embodiment of the invention, the first end of the auxiliary channel is located at such a distance from the first end of the gas supply channel that when a gas admission valve assembly is attached to the cylinder head, the first end of the auxiliary channel opens into an area between an inner wall surface and an outer wall surface of the gas admission valve assembly. The gas admission valve assembly can thus be provided with a connection point for the auxiliary channel between the inner wall surface and the outer wall surface.
According to an embodiment of the invention, the top surface of the cylinder head is provided around the first end of the gas supply channel with an inner sealing groove and an outer sealing groove, each sealing groove being configured to receive a sealing element, and the first end of the auxiliary channel is located between the inner sealing groove and the outer sealing groove. This allows effective sealing of the auxiliary channel both outwards and towards the gas supply channel.
According to an embodiment of the invention, the top surface of the cylinder head is provided with a sealing groove arranged around the first end of the auxiliary channel. This allows effective sealing of the joint between the end of the auxiliary channel and the gas admission valve assembly.
According to an embodiment of the invention, the auxiliary channel is a prechamber gas supply channel, and the second end of the auxiliary channel is arranged at a location allowing connection to a prechamber injector for introducing the gaseous fuel into the prechamber. By using the auxiliary channel as a prechamber gas supply channel, the need for a double-wall pipe outside the cylinder head is avoided, which simplifies the construction of the fuel supply system.
According to an embodiment of the invention, the auxiliary channel is a prechambergas leak detection channel, and the second end of the auxiliary channel is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole. This allows using the same leak detector to detect gaseous fuel leaking both from the prechamber injector and from elsewhere of the fuel supply system.
According to an embodiment of the invention, the cylinder head further comprises a first auxiliary channel, which a prechamber gas supply channel, and a second auxiliary channel, which is a prechamber gas leak detection channel.
The cylinder head assembly according to the invention comprises a cylinder head defined above and a gas admission valve assembly arranged on the top surface of the cylinder head.
According to an embodiment of the invention, the gas admission valve assembly comprises a connecting block for attaching the gas admission valve to the cylinder head, wherein the connecting block is arranged against the top surface of the cylinder head and comprises an inner wall surface surrounding the first end of the gas supply channel and an outer wall surface surrounding the first end of the gas supply channel. The area between the inner wall surface and the outer wall surface can be used for providing connections for one or more auxiliary channels.
According to an embodiment of the invention, the auxiliary channel is configured to connect the prechamber hole to the gas admission valve assembly between an inner wall surface and an outer wall surface of the gas admission valve assembly. This allows connecting the auxiliary channel to a leak detector.
The piston engine according to the invention comprises a cylinder head assembly defined above.
The connecting block according to the invention for attaching a gas admission valve to the upper surface of a cylinder head defined above is configured to receive a gas admission valve and comprises a gas channel that is configured to connect to the first end of the auxiliary channel of the cylinder head.
According to an embodiment of the invention, the gas channel is configured to connect to a gas supply space forming between the connecting block and the gas admission valve in a mounted state of the gas admission valve. This allows gas supply through the auxiliary channel. According to an embodiment of the invention, the gas channel is configured to connect an auxiliary channel of the cylinder head to a leak detector. This allows the use of the auxiliary channel as a gas leak detection channel.
According to an embodiment of the invention, the connecting block comprises a first gas channel configured to connect to the first end of a first auxiliary channel of the cylinder head and a second gas channel configured to connect to the first end of a second auxiliary channel of the cylinder head. The gas channels of the connecting block can thus connect to both a prechamber gas supply channel and a prechamber gas leak detection channel.
The method according to the invention for detecting leakages of gaseous fuel in a piston engine comprises the steps of introducing intake air into a main combustion chamber of a cylinder of the engine via an inlet port located in the cylinder head of said cylinder, introducing gaseous fuel from a gas admission valve assembly attached to the cylinder head into the inlet port through a gas supply channel arranged in the cylinder head and having a first end that opens onto a top surface of the cylinder head and a second end that opens into the inlet port, conducting possibly leaking fuel from a prechamber assembly via an auxiliary channel to the gas admission valve assembly and further to a leak detector, and using said leak detector to detect gaseous fuel conducted via the auxiliary channel.
In the method according to the invention, the auxiliary channel is thus used as a leak channel conducting possibly leaking fuel to a leak detector. This reduces the number of joints in the fuel supply system of the engine.
According to an embodiment of the invention, the leak detector is a gas detector or a pressure sensor.
According to an embodiment of the invention, said leak detector is used for monitoring possible gas leakages of a gas supply pipe supplying gaseous fuel to the gas admission valve assembly. The same leak detector is thus used for detecting gas leakages from both the prechamber assembly and the gas supply Pipe. Brief description of the drawinqs
Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which
Fig. 1 shows a perspective view of a cylinder head according to an embodiment of the invention,
Fig. 2 shows an enlarged view of detail E of figure 1 ,
Fig. 3 shows a cross-sectional view of a cylinder head assembly according to an embodiment of the invention, and
Fig. 4 shows another cross-sectional view of the cylinder head assembly of figure 3.
Detailed description of embodiments of the invention
Figure 1 shows a cylinder head 1 according to an embodiment of the invention. The cylinder head 1 is a cylinder head of a large piston engine. The expression “large piston engine” refers here to an engine having a cylinder diameter of at least 150 mm. The engine can be, for instance, an engine that is used as a main or an auxiliary engine in a ship or an engine that is used at a power plant for driving a generator for producing electricity. The engine is a four-stroke engine. Figures 3 and 4 show schematically an 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 an own cylinder head 1 . The cylinder head 1 can be a one-piece part.
The engine in which the cylinder head 1 is used is configured to be operable using at least a first, gaseous fuel. The expression “gaseous fuel” refers here to a fuel that is gaseous in atmospheric pressure and at a temperature of 20 °C. The first fuel can be, for instance, natural gas or biogas. The term “biogas” refers here to a gas that mainly consists of methane and which is obtained from renewable sources. The biogas can be produced for example from organic waste. Natural gas could be stored either as a liquefied gas (LNG) or compressed gas (CNG). Biogas could be stored in a similar manner. Instead of methane-based fuels, the first fuel could be, for instance, hydrogen or ammonia or a mixture of two or more types of gaseous fuel. The engine can be further configured to be operable using a second fuel. The second fuel can be either gaseous fuel or liquid fuel. If the first fuel is natural gas or biogas, the second fuel could be, for instance, hydrogen. Alternatively, the second fuel could be liquid fuel, such as light fuel oil or heavy fuel oil. The engine can also be operable using a third fuel or even further fuels.
The engine can thus be a gas engine, a dual-fuel engine or a multi-fuel engine. The engine is thus configured to be operable using at least one gaseous fuel. In addition to that, the engine can be configured to be operable using one or more additional gaseous fuels, and/or one or more liquid fuels.
The engine can be configured to be operable using mixtures of different fuels. For instance, the engine could be operable using a mixture of hydrogen and some other gaseous fuel and/or a mixture of ammonia and some other gaseous fuel.
When the engine is operated using a gaseous fuel, it can utilize a liquid fuel, such as light fuel oil as a pilot fuel facilitating ignition of the gaseous fuel. However, that is not necessary, but the gaseous fuel could be self-igniting or spark plugs or other ignition means could be used for igniting the gaseous fuel.
The cylinder head 1 has a bottom surface 1A configured to delimit an upper end of a main combustion chamber 2 of a cylinder 3, and a top surface 1 B facing an opposite direction than the bottom surface 1A. The cylinders 3 of the engine do not need to be in an upright position, but the cylinders 3 can be inclined from the vertical direction. For instance in a V-engine, the upper ends of the cylinders 3 can be located farther outwards from the longitudinal center line of the engine than the lower ends. The term “bottom surface” thus refers to that side of the cylinder head 1 that is facing the main combustion chamber 2, but the bottom surface 1A does not need to be a horizontal surface facing downwards.
The top surface 1 B of the cylinder head 1 is configured to receive a gas admission valve assembly 4 that is attachable to the cylinder head 1. The gas admission valve assembly 4 can thus be arranged against the top surface 1 B of the cylinder head 1 and attached to the cylinder head 1 , for example by means of bolts. Figure 2 shows attachment holes 27 for attaching the gas admission valve assembly 4 to the cylinder head 1. The gas admission valve assembly 4 comprises a gas admission valve 5 for controlling supply of gaseous fuel into the cylinder 3. The gas admission valve 5 is connected to a gas supply pipe 26 for receiving the gaseous fuel. The gas supply pipe 26 is a double-wall pipe. The gas admission valve 5 is a controllable valve allowing introducing the correct amount of gaseous fuel into the main combustion chamber 2.
The cylinder head 1 comprises an inlet port 11 for introducing intake air into the main combustion chamber 2, and a gas supply channel 12 having a first end 12A that opens onto the top surface 1 B of the cylinder head 1 and a second end 12B that opens into the inlet port 11 of the cylinder head 1 for introducing gaseous fuel into the inlet port 11 . The cylinder head 1 also comprises an exhaust port 25 for discharging exhaust gas from the main combustion chamber 2. The gas admission valve assembly 4 is located above the first end 12A of the gas supply channel 12 to allow supply of gaseous fuel from the gas admission valve 5 into the gas supply channel 12 and further into the inlet port 11 and the main combustion chamber 2. Because the gas supply channel 12 is arranged within the cylinder head 1 , a double-wall pipe is not needed between the gas admission valve assembly 4 and the inlet port 11 .
The cylinder head 1 further comprises a prechamber hole 7. The prechamber hole 7 is a cavity formed within the cylinder head 1 . In the embodiment of the figures, the prechamber hole 7 extends from the top surface 1A to the bottom surface 1 B of the cylinder head 1. The prechamber hole 7 is configured to receive and/or form a prechamber assembly comprising a prechamber 9 and a prechamber injector 10 configured to introduce gaseous fuel into the prechamber 9. In the embodiment of the figures, the prechamber assembly protrudes into the main combustion chamber 2. The prechamber assembly can be made of several parts. The prechamber 9 is in fluid communication with the main combustion chamber 2. Gases can thus flow from the prechamber 9 into the main combustion chamber 2 and from the main combustion chamber 2 into the prechamber 9.
The cylinder head 1 also comprises holes 28 for receiving intake valves and holes 29 for receiving exhaust valves.
The cylinder head 1 comprises at least one auxiliary channel 13, 14 having a first end 13A, 14A that opens onto the top surface 1 B of the cylinder head 1 and a second end 13B, 14B that opens into the prechamber hole 7. The first end 13A, 14A of the auxiliary channel 13, 14 is located in an area that is configured to be covered by the gas admission valve assembly 4 in a mounted state of a cylinder head assembly comprising the cylinder head 1 and the gas admission valve assembly 4.
The auxiliary channels 13, 14 allow flow of gaseous fuel between the prechamber hole 7 and the top surface 1 B of the cylinder head 1 . Flow from the gas admission valve assembly 4 to the prechamber assembly and/or in the opposite direction is thus allowed. This reduces the need of double-wall pipes in the fuel supply system of the engine and reduces the number of potential gas leakage locations.
In the embodiment of the figures, the cylinder head 1 comprises a first auxiliary channel 13 and a second auxiliary channel 14. Each of the auxiliary channels 13, 14 has a first end 13A, 14A and a second end 13B, 14B as described above. However, the cylinder head 1 could be provided with only one of the auxiliary channels 13, 14.
In the embodiment of the figures, the first auxiliary channel 13 is a prechamber gas supply channel 13, and the second end 13B of the first auxiliary channel 13 is arranged at a location allowing connection to a prechamber injector 10 for introducing the gaseous fuel into the prechamber 9. Main part of the gaseous fuel introduced into the cylinder 3 is introduced via the gas supply channel 12 into the inlet port 11 and further into the main combustion chamber 2. The gaseous fuel introduced into the inlet port 11 flows during the intake stroke into the main combustion chamber 2. The fuel introduced into the inlet port 11 can form a lean mixture with the intake air. Part of the gaseous fuel is introduced into the prechamber 9. This allows forming a richer mixture in the prechamber 9. The richer fuel/air mixture can be ignited in the prechamber 9, for instance by means of a spark plug. The combustion of the richer mixture facilitates the ignition of the leaner mixture in the main combustion chamber 2.
In the embodiment of the figures, the second auxiliary channel 14 is a prechambergas leak detection channel 14, and the second end 14B of the second auxiliary channel 14 is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole 7. If a gas leak occurs in the prechamber assembly, the leaking fuel can be conducted via the second auxiliary channel 14 to the gas admission valve assembly 4. From the gas admission valve assembly 4, the leaking fuel can be further conducted to a leak detector. Alternatively, the gas admission valve assembly can be provided with a leak detector. The leak detector can be a gas detector. A gas detector is configured to detect the presence of a certain gas. Alternatively, the leak detector could be a pressure sensor. Leaking fuel can be conducted into a closed volume or into a volume where the outflow of gases is restricted, and the pressure sensor can be arranged to monitor the pressure in said volume, thus detecting the presence of leaking fuel.
The same leak detector can be configured to detect leakages also elsewhere in the fuel supply system. For instance, leakages of the gas supply pipe 26 can be conducted in an outer pipe of the gas supply pipe 26 to the same leak detector as the leakages from the prechamber assembly. The outer pipe of the gas supply pipe 26 can be used for conducting leakage from the prechamber assembly to the leak detector.
In the embodiment of the figures, the gas admission 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 gas supply channel 12. The outer wall surface 16 is arranged radially outwards from the inner wall surface 15. In the embodiment of the figures, the first end 13A, 14A of each of the auxiliary channels 13, 14 is located at such a distance from the first end 12A of the gas supply channel 12 that when a gas admission valve assembly 4 is attached to the cylinder head 1 , the first end 13A, 14A of the auxiliary channel 13, 14 opens into an area between the inner wall surface 15 and the outer wall surface 16.
In the embodiment of the figures, the top surface 1 B of the cylinder head 1 is provided around the first end 12A of the gas supply channel 12 with an inner sealing groove 17 and an outer sealing groove 18. Each of the sealing grooves 17, 18 is configured to receive a sealing element 19, 20. The sealing element can be, for instance, an O-ring. The first end 13A, 14A of each of the auxiliary channels 13, 14 is located between the inner sealing groove 17 and the outer sealing groove 18. The sealing element 19 arranged in the inner sealing groove 17 thus forms a seal between the first end 12A of the gas supply channel 12 and the first end 13A, 14A of each of the first auxil iary channel 13 and the second auxiliary channel 14. The sealing element 20 arranged in the outer sealing groove 18 forms a seal preventing leakages from the auxiliary channels 13,14 radially outwards.
In the embodiment of the figures, the top surface 1 B 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. The sealing element 22 can be, for instance, an O-ring.
The cylinder head 1 and the gas admission valve assembly 4 arranged on the top surface of the cylinder head 1 form a cylinder head assembly. In the embodiment of the figures, the gas admission valve assembly 4 comprises a connecting block 6 for attaching the gas admission valve 5 to the cylinder head 1 . The connecting block 6 is arranged against the top surface 1 B of the cylinder head 1 and the inner wall surface 15 surrounding the first end 12A of the gas supply channel 12 and the outer wall surface 16 surrounding the first end 12A of the gas supply channel 12 are part of the connecting block 6.
The connecting block 6 is configured to receive the gas admission valve 5. In a mounted state of the gas admission valve 5, a gas supply space 24 is formed between the connecting block 6 and the gas admission valve 5. The connecting block comprises a gas channel 23 that is configured to connect to the first end 13A of the first the 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, gaseous fuel is conveyed to the gas admission valve 5 and into the gas supply space 24. From the gas supply space 24, the fuel can flow via the gas channel 23 into the first auxiliary channel 13 and further to the prechamber injector 10. The prechamber injector 10 can be used for injecting the fuel into the prechamber 9.
The connecting block 6 comprises a gas leakage channel that is in the mounted state of the connecting block 6 connected to the second auxiliary channel 14. Via the second auxiliary channel 14, leaking fuel can be conducted from the prechamber hole 7 to the connecting block 6. The leaking fuel can be conducted into the outer pipe of the gas supply pipe 26 and further to a leak detector, such as a gas detector or pressure sensor. The same leak detector can thus be configured to monitor the space between the inner pipe and the outer pipe of the gas supply pipe 26 and the prechamber assembly. The connecting block 6 could be configured to comprise a hole that is configured to receive a leak detector. The same leak detector could be arranged to monitor leakages of the prechamber assembly and the gas supply pipe 26. It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.

Claims

Claims:
1. A cylinder head (1 ) for a piston engine, the cylinder head (1 ) having a bottom surface (1A) configured to delimit an upper end of a main combustion chamber (2) of a cylinder (3) of a piston engine, and a top surface (1 B) facing an opposite direction than the bottom surface (1 A), the top surface (1 B) being configured to receive a gas admission valve assembly (4) that is attachable to the cylinder head (1 ), the cylinder head (1 ) comprising
- a prechamber hole (7),
- an inlet port (11 ) for introducing intake air into the main combustion chamber (2), and
- a gas supply channel (12) having a first end (12A) that opens onto the top surface (1 B) of the cylinder head (1 ) and a second end that opens into the inlet port (11 ) of the cylinder head (1 ) for introducing gaseous fuel into the inlet port (11 ), characterized in that the cylinder head (1 ) comprises an auxiliary channel (13, 14) having a first end (13A, 14A) that opens onto the top surface (1 B) of the cylinder head (1 ) and a second end (13B, 14B) that opens into the prechamber hole (7), wherein the first end (13A, 14A) of the auxiliary channel (13, 14) is located in an area that is configured to be covered by the gas admission valve assembly (4).
2. A cylinder head (1 ) according to claim 1 , wherein the first end (13A, 14A) of the auxiliary channel (13, 14) is located at such a distance from the first end (12A) of the gas supply channel (12) that when a gas admission valve assembly (4) is attached to the cylinder head (1 ), the first end (13A, 14A) of the auxiliary channel (13, 14) opens into an area between an inner wall surface (15) and an outer wall surface (16) of the gas admission valve assembly (4).
3. A cylinder head (1 ) according to claim 1 or 2, wherein the top surface (1 B) of the cylinder head (1 ) is provided around the first end (12A) of the gas supply channel (12) with an inner sealing groove (17) and an outer sealing groove (18), each sealing groove (17, 18) being configured to receive a sealing element (19, 20), and the first end (13A, 14A) of the auxiliary channel (13, 14) is located between the inner sealing groove (17) and the outer sealing groove
4. A cylinder head (1 ) according to any of claims 1-3, wherein the top surface (1 B) 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. A cylinder head (1 ) according to any of the preceding claims, wherein the auxiliary channel (13, 14) is a prechamber gas supply channel (13), and the second end (13B) of the auxiliary channel (13) is arranged at a location allowing connection to a prechamber injector (10) for introducing the gaseous fuel into the prechamber (9).
6. A cylinder head (1 ) according to any of claims 1 -4, wherein the auxiliary channel (13, 14) is a prechamber gas leak detection channel (14), and the second end (14B) of the auxiliary channel (14) is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole (7).
7. A cylinder head (1 ) according to claim 5, wherein the cylinder head (1 ) further comprises a second auxiliary channel (14), which is a prechamber gas leak detection channel, the second auxiliary channel (14) having a first end (14A) that opens onto the top surface (1 B) of the cylinder head (1 ) and a second end (14B) that opens into the prechamber hole (7), wherein the first end (14A) of the second auxiliary channel (14) is located in the area that is configured to be covered by the gas admission valve assembly (4), and the second end (14B) of the second auxiliary channel (14) is arranged at a location allowing venting of possibly leaking gaseous fuel from the prechamber hole (7).
8. A cylinder head assembly for a piston engine, the cylinder head assembly comprising a cylinder head (1 ) according to any of the preceding claims and a gas admission valve assembly (4) arranged on the top surface (1 B) of the cylinder head (1 ).
9. A cylinder head assembly according to claim 8, wherein the gas admission valve assembly (4) comprises a connecting block (6) for attaching the gas admission valve (4) to the cylinder head (1 ), wherein the connecting block (6) is arranged against the top surface (1 B) of the cylinder head (1 ) and comprises an inner wall surface (15) surrounding the first end (12A) of the gas supply channel (12) and an outer wall surface (16) surrounding the first end (12A) of the gas supply channel (12).
10. A cylinder head assembly according to claim 8 or 9, wherein the auxiliary channel (13, 14) is configured to connect the prechamber hole (7) to the gas admission valve assembly (4) between an inner wall surface (15) and an outer wall surface (16) of said gas admission valve assembly (4).
11. A piston engine comprising a cylinder head assembly according to any of claims 8 to 10.
12. A connecting block (6) for attaching a gas admission valve (4) to the upper surface (1 B) of a cylinder head (1 ) according to any of claims 1-8, wherein the connecting block (6) is configured to receive a gas admission valve (4) and comprises a gas channel (23) that is configured to connect to the first end (13A, 14A) of the auxiliary channel (13, 14) of the cylinder head (1 ).
13. A connecting block (6) according to claim 12, wherein the gas channel (23) is configured to connect to a gas supply space (24) forming between the connecting block (6) and the gas admission valve (4) in a mounted state of the gas admission valve (4).
14. A connecting block (6) according to claim 12, wherein the gas channel (23) is configured to connect an auxiliary channel (14) of the cylinder head (1 ) to a leak detector.
15. A connecting block (6) according to any of claims 12-14 for attaching a gas admission valve (4) to the upper surface (1 B) of a cylinder head (1 ) according to claim 7, wherein the connecting block (6) comprises a second gas channel configured to connect to the first end (14A) of the second auxiliary channel (14) of the cylinder head (1 ).
16. A method of detecting leakages of gaseous fuel in a piston engine, the method comprising
- introducing intake air into a main combustion chamber (2) of a cylinder (3) of the engine via an inlet port (11 ) located in the cylinder head (1 ) of said cylinder (3), and
- introducing gaseous fuel from a gas admission valve assembly (4) attached to the cylinder head (1 ) into the inlet port (11 ) through a gas supply channel (12) arranged in the cylinder head (1 ) and having a first end (12A) that opens onto a top surface (1 B) of the cylinder head (1 ) and a second end that opens into the inlet port (11 ), characterized in that the method comprises
- conducting possibly leaking fuel from a prechamber assembly (10) via an auxiliary channel (13, 14) to the gas admission valve assembly (4) and further to a leak detector, and - using said leak detector to detect gaseous fuel conducted via the auxiliary channel (13, 14).
17. A method according to claim 16, wherein the leak detector is a gas detector or a pressure sensor.
18. A method according to claim 16 or 17, wherein said leak detector is used for monitoring possible gas leakages of a gas supply pipe (26) supplying gaseous fuel to the gas admission valve assembly (4).
PCT/FI2022/050525 2022-08-12 2022-08-12 Cylinder head, cylinder head assembly, piston engine, connecting block and method of detecting leakages of gaseous fuel in a piston engine WO2024033562A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000008960A (en) * 1998-06-19 2000-01-11 Osaka Gas Co Ltd Subsidiary chamber type internal combustion engine
WO2012032672A1 (en) * 2010-09-08 2012-03-15 トヨタ自動車株式会社 Internal combustion engine
US20150267631A1 (en) * 2013-03-22 2015-09-24 Kawasaki Jukogyo Kabushiki Kaisha Fuel supply controlling device for divided-chamber gas engine
WO2020060416A1 (en) * 2018-09-20 2020-03-26 Bergen Engines As Cylinder head for a combustion engine, and a method for supply of prechamber gas in a cylinder head

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000008960A (en) * 1998-06-19 2000-01-11 Osaka Gas Co Ltd Subsidiary chamber type internal combustion engine
WO2012032672A1 (en) * 2010-09-08 2012-03-15 トヨタ自動車株式会社 Internal combustion engine
US20150267631A1 (en) * 2013-03-22 2015-09-24 Kawasaki Jukogyo Kabushiki Kaisha Fuel supply controlling device for divided-chamber gas engine
WO2020060416A1 (en) * 2018-09-20 2020-03-26 Bergen Engines As Cylinder head for a combustion engine, and a method for supply of prechamber gas in a cylinder head

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