A fuel delivery and leakage handling system for a multi-cylinder internal combustion engine, a fuel connection block, method of retrofitting a used cylinder head of an internal combustion piston engine and an internal combustion piston engine

Abstract

Invention relates to a retrofit concept which provides solution to the need of improving performance of existing large dual fuel engines. The invention presents a fuel delivery and leakage handling system for connecting a fuel feed line and a leakage fluid line in a cylinder head and multiple cylinder heads (102, 102') in an internal combustion piston engine, and a fuel connection block for connecting a fuel feed line and a leakage fluid line in a cylinder head (102). Invention relates also to method of retrofitting a used cylinder head (102) of an internal combustion piston engine, and an internal combustion piston engine.

Description

A fuel delivery and leakage handling system for a multi-cylinder internal combustion engine, a fuel connection block for connecting fuel feed line and leakage line to a cylinder head of an internal combustion piston engine, method of retrofitting a used cylinder head of an internal combustion piston engine and an internal combustion piston engineTechnical field

[0001] The present invention relates to a fuel delivery and leakage handling system for a multi-cylinder internal combustion engine.

[0002] The present invention relates to a fuel connection block for connecting fuel feed line and leakage line to a cylinder head of an internal combustion piston engine.

[0003] The present invention relates to a method of retrofitting a used cylinder head of an internal combustion piston engine.

[0004] The present invention relates to an internal combustion piston engine.Background art

[0005] Climate change has a significant impact on the future of large piston engines in marine vessels, and land-based power plants. With the push to reduce greenhouse gas emissions, international bodies like the International Maritime Organization have set stricter regulations on carbon dioxide (CO2), sulphur oxides (SOx), and nitrogen oxides (NOx) emissions. This has compelled the marine industry to innovate and develop cleaner engine technologies. The global focus on decarbonization has led to the promotion of alternative fuels and hybrid propulsion systems. Traditional large piston engines are being redesigned to either operate on or integrate with lower-carbon fuels such as liquefied natural gas (LNG), hydrogen, or biofuels. LNG has been widely used in so-called dual fuel engines, where LNG as a main fuel is ignited by direct injected pilot fuel, such as light fuel oil (LFO). Such an engine is also provided with a back-up LFO fuelsystem which can be used for running the engine instead of LNG if so desired or needed.

[0006] The marine industry is increasingly exploring alternative fuels such as LNG, ammonia, and methanol. Large piston engines are being developed or retrofitted to accommodate these fuels, which present unique challenges in terms of storage, handling, and combustion. Existing fleets need to be retrofitted to meet new standards, which affects engine design.

[0007] An object of the invention is to provide a retrofit concept which provides solution to the need of improving performance of existing large dual fuel engines.Disclosure of the Invention

[0008] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[0009] According to an aspect of the invention a fuel delivery and leakage handling system for connecting a fuel feed line and a leakage fluid line in a cylinder head, and multiple cylinder heads in an internal combustion piston engine, comprises- first interface in connection with the cylinder head for coupling a first fuel line to the cylinder head,- a second interface in connection with the cylinder head for coupling a second fuel line to the same cylinder head, and- first interface, comprising a first opening for fuel feed line and a second opening for leakage line, both openings being circumscribed by a first groove for a first sealing ring arranged to the first interface, wherein a second groove for a second sealing ring is arranged to the first interface inside the first groove circumscribing only the first opening,- the second interface, comprising a third opening for fuel feed line and a fourth opening for leakage line, both openings being circumscribed by a third groove for a third sealing ring arranged to the second interface, wherein a fourth groove fora fourth sealing ring is arranged to the second interface inside the third groove circumscribing only the third opening,and the fuel delivery and leakage handling system further comprise- a first channel system for pressurized fuel in connection with the cylinder head fluidly connecting a fuel feeding channel in the cylinder head, the first opening and the third opening with each other,- a second channel system for leakage fluid in connection with the cylinder head extending between a leakage line in the cylinder head, the second opening and the fourth opening.

[0010] The fuel delivery and leakage handling system for connecting multiple cylinder heads provides an advantageous manner to provide fuel introduction into cylinders of an engine and conveyance of possible leakage fluid away from cylinders, particularly but not necessarily in retrofit fuel conversion applications where cylinder heads are replaced with new ones. The interfaces in the cylinder head makes it possible to connect the fuel and leakage channels to fuel feeding system for feeding gaseous fuel and for connecting the leakage channel in cylinder to leakage channel for conveying possible leakage to further processing. This also facilitates retrofit conversion of a dual fuel cylinder head to be compatible for gaseous fuel operation.

[0011] According to an aspect of the invention the fuel connection system is provided with a closing valve in the second channel system, which comprises an inlet, which inlet of the closing valve is solely in flow connection with the fuel feed line in the cylinder head, and an outlet, which outlet of the closing valve is in flow connection with both the second opening in the first interface and the fourth opening in the second interface, a closing element, such as a piston, which is arranged axially movably between a first position at which the closing element closes flow connection between the inlet and the outlet, and a second position at which the closing element opens flow connection between the inlet and the outlet, wherein the closing element is configured to open when pressure in the inlet is greater than a threshold pressure which needs to be exceeded before the closing element changes its position from the first position to the second position.

[0012] Such a closing valve makes it possible to convey leakage away from the engine in such a way that leakage fluid will not enter other cylinder heads of the engine but opens only in such cylinder head where leakage pressure causes the valve to open.

[0013] According to an aspect of the invention the closing element is a piston assembly, one end of which extending out from the fuel connection block for visual indication of position of the closing element. This way a leaking cylinder head can be easily pinpointed e.g. manually.

[0014] According to an aspect of the invention a number of cylinder heads in cylinders of an internal combustion engine are arranged as a group of successive cylinder heads wherein in each two successive cylinder heads, the first one of the cylinder heads is in connection with the second one of the cylinder heads by a double wall pipe, which is connected to one of the first and second interface in the first one of the cylinder heads and to one of the first and second interface in the second one of the cylinder heads.

[0015] This way the fuel delivery to several cylinder heads and leakage removal from several cylinder heads can be arranged to one location in the handling system.

[0016] According to an aspect of the invention the system comprises a fuel connection block, through which the fuel feed line in the cylinder head is connected to the first fuel line and the second fuel line, wherein the fuel connection blocks are arranged as a group of successive fuel connection blocks wherein in each two successive fuel connection blocks the first one of the fuel connection blocks is in connection with the second one of the fuel connection blocks by a double wall pipe, which is connected to one of the first and second interface in the first one of the fuel connection blocks, and to one of the first and second interface in the second one of the fuel connection blocks.

[0017] The fuel connection block provides an advantageous manner to provide fuel introduction into cylinders of an engine and conveyance of possible leakage fluid away from cylinders particularly in retrofit fuel conversion applications where existing cylinders are used after the conversion.

[0018] According to an aspect of the invention the concept includes a fuel connection block for connecting fuel feed line and leakage line to a cylinder head of an internal combustion piston engine, comprising- a first interface four coupling a first fuel line to the connection block,- a second interface for coupling a second fuel line to the connection block, - a third interface for coupling the connection block to the cylinder head, wherein- the third interface has a planar interface surface comprising a fifth opening for fuel feed line and a sixth opening for leakage line, both openings being circumscribed by a fifth groove for a fifth sealing ring arranged to the third interface, wherein a sixth groove for a sixth sealing ring is arranged to the third interface inside the fifth groove, circumscribing only the fifth opening,- the first interface comprising a first opening for fuel feed line and a second opening for leakage line, both openings being circumscribed by a first groove for a first sealing ring arranged to the first interface, wherein a second groove for a second sealing ring is arranged to the first interface inside the first groove circumscribing only the first opening,- the second interface comprising a third opening for fuel feed line and a fourth opening for leakage line, both openings being circumscribed by a third groove for a third sealing ring arranged to the second interface, wherein a fourth groove for a fourth sealing ring is arranged to the second interface inside the third groove circumscribing only the third opening,and further comprising- a first channel system for pressurized fuel arranged inside the fuel connection block fluidly connecting a fuel feeding channel, the first opening and the third opening with each other,- a second channel system for leakage fuel arranged inside the fuel connection block extending between the leakage line in the cylinder head, the second opening and the fourth opening.

[0019] The fuel connection block provides an advantageous manner to provide fuel introduction into cylinders of an engine and conveyance of possible leakage fluid away from cylinders particularly in retrofit fuel conversion applications. The connection block makes it possible to connect the fuel and leakage channels inthe cylinder after conversion to fuel feeding system for feeding gaseous fuel and for connecting the leakage channel in cylinder to leakage channel for conveying possible leakage to further processing. This facilitates retrofit conversion of a dual fuel cylinder head to be compatible for gaseous fuel operation.

[0020] According to an aspect of the invention the fifth groove is of elongated rectangular shape with two semi-circular end sections and two parallel groove sections connecting the end sections, and the sixth groove is a circular groove in proximity to one of the semi-circular ends, and the fifth opening is of circular cross section and is concentric with the sixth groove. This makes it possible to seal the channels in the third interface in way compatible with the corresponding channels and surface in the cylinder head.

[0021] According to an aspect of the invention in the fifth opening and the sixth opening are of circular cross section and distance between the fifth opening and the sixth opening is more than four times the diameter of the fifth opening. This makes it possible to connect the channels in the third interface in a way compatible with the cylinder head.

[0022] According to an aspect of the invention cross-sectional area of the second and fourth openings is 0,2 - 0,5 times cross sectional area of the first and third openings. The second and the fourth openings are for connecting leakage channel and the first and the third openings are for connecting fuel channel. The area in the connection is limited and this feature makes sure that fuel delivery is at adequate level without hampering leakage detection.

[0023] According to an aspect of the invention the first channel system comprises a primary flow connection between the first opening and the third opening, and the fifth opening is connected to the primary flow connection via a secondary flow connection, wherein cross-sectional area of the primary flow connection is at least 5 times greater than the cross-sectional area of the secondary flow connection. The first opening and the third opening and the primary flow connection are for connecting fuel channel between two cylinder heads with each other whereas the secondary flow connection is for connecting the connection block to the fuel channel in the cylinder head. With this feature it is made sure that fueldelivery to all of the cylinder heads which are connected with each other making use of connection blocks can be secured.

[0024] According to an aspect of the invention mean cross-sectional area of the first channel system is 2 to 5 times larger than mean cross-sectional area of the second channel system. With this feature it is made sure that fuel delivery can be secured.

[0025] According to an aspect of the invention fuel connection block is provided with a closing valve in the second channel system, which comprises- an inlet, which inlet of the closing valve is solely in flow connection with the sixt opening in the third interface, and- an outlet, which outlet of the closing valve is in flow connection with both the second opening in the first interface and the fourth opening in the second interface,- a closing element, such as a piston, which is arranged axially movably between a first position, at which the closing element closes flow connection between the inlet and the outlet, and a second position, at which the closing element opens flow connection between the inlet and the outlet, wherein the closing element is configured to open when pressure in the inlet is greater than a threshold pressure which needs to be exceeded before the closing element changes its position from the first position to the second position.

[0026] Such a closing valve makes it possible to convey leakage away from the engine in such a way that leakage fluid will not enter other cylinder heads of the engine but opens only in such cylinder head where leakage pressure causes the valve to open.

[0027] According to an aspect of the invention the closing element is a piston assembly, one end of which extending out from the fuel connection block for visual indication of position of the closing element.

[0028] This way a leaking cylinder head can be easily pinpointed e.g. manually.

[0029] According to an aspect of the invention the retrofit concept includes a fuel delivery and leakage handling system for a multi-cylinder internal combustion engine, comprising a number of fuel connection blocks according to theinvention, the aspects of which being explained above, which is arranged as a group of successive fuel connection blocks wherein in each two successive fuel connection blocks the first one of the fuel connection blocks is in connection with the second one of the fuel connection blocks by a double wall pipe, which is connected to one of the first and second interface in the first one of the fuel connection blocks, and to one of the first and second interface in the second one of the fuel connection blocks.

[0030] This way the fuel delivery to several cylinder heads and leakage removal from several cylinder heads can be arranged to one location in the handling system.

[0031] According to an aspect of the invention the retrofit concept may include a start valve extension part for a cylinder head of a compressed air started internal combustion piston engine, the extension part comprisinga rotationally symmetrical body having a central longitudinal axis and a first axial end and a second axial end, wherein the second axial end is configured for retaining a start air valve in the cylinder head, when assembled for use, a first axially bordered interface area on outer surface of the body, bordered by a first sealing arrangement and a second sealing arrangement in circumference of the body,a first fluid channel arranged to the first axially bordered interface area in the extension part extending transversely across the extension part,a second axially bordered interface area on outer surface of the body, bordered by the second sealing arrangement and a third sealing arrangement in circumference of the body,a second fluid channel arranged to a the second axially bordered interface area in the extension part extending transversely across the extension part, whereinthe first sealing arrangement comprises two separate seals arranged at axial distance from each other, circumscribing an outer surface of the body forming an axial gap between the seals, andthe body is provided with an internal channel which extends from the axial gap to the second fluid channel or to the second axially bordered interface area.

[0032] The start valve extension according to the invention makes it possible to convert spaces for quill pipes in existing cylinder head into a gas tight flow channels for feeding gaseous fuel and for handling and / or detecting leakage in the cylinder. This facilitates retrofit conversion of a dual fuel cylinder head to be compatible for gaseous fuel operation. The start valve extension part according to the invention makes it possible to perform an upgrade of an existing dual fuel engine to be operated with so called alternative fuels. Such a start valve extension part facilitates the use of the fuel connection block in retrofit conversion.

[0033] According to an aspect of the invention the one or both of the first and the second fluid channels comprise a transverse through hole in the body.

[0034] Through hole is simple to manufacture and therefore it is a preferred embodiment for the fluid channel.

[0035] According to an aspect of the invention both the first and the second fluid channels comprise a transverse through hole in the body and the holes are parallel to each other, perpendicular to longitudinal axis of the extension part. This provides accurate compatibility with existing cylinder head of a dual fuel engine.

[0036] According to an aspect of the invention both the first and the second fluid channels comprise a transverse through hole in the body and the holes are parallel to each other, perpendicular to longitudinal axis of the extension part and the transverse through hole is arranged in the middle of radial cross section to the body. This provides the most accurate compatibility with existing cylinder head of a dual fuel engine.

[0037] According to an aspect of the invention the internal channel comprises an axial boring section which extend from a first end of the body to the second fluid channel, and a radial boring section, which extends from the axial gap between the seals of the first sealing arrangement, to the axial boring section, and wherein the axial boring section is plugged at its end at the first end of the body.

[0038] This way leakage fluid from the axial gap can be led to the second fluid channel safely.

[0039] According to an aspect of the invention at least one or both of the first and the second fluid channels comprise a recess within respective axially bordered interface area in outer surface of the body, which recess extends across the body in transverse direction.

[0040] Such a recess provides flow channel without a need of making borings to the start valve extension part.

[0041] According to an aspect of the invention the recess comprises a circumferential groove which extends over at least half of the circumference. Such a groove connects the fluid channels in the cylinder head.

[0042] According to an aspect of the invention the second fluid channel has greater cross-sectional area than the first fluid channel, wherein the first fluid channel is closer to the first axial end of the start valve extension part. The second fluid channel is configured for leading leakage out from the cylinder, and having greater volume improves collection of leakage fluid.

[0043] According to an aspect of the invention cross sectional area of the second fluid channel is at least 1,5 times larger than the first fluid channel, advantageously 2 - 10 times larger. This has been found to provide efficient operation of the leakage collection and / or detection.

[0044] According to an aspect of the invention the seals in the first sealing arrangement comprise two annular grooves on the body and resilient sealing rings, such as O-rings, arranged to the grooves and axial distance between the sealing rings is less than 1,5 times width of one of the grooves. This way the volume between the sealing rings is substantially small and leakage fluid conveyance to the second fluid channel is therefore substantially swift and leakage detection is improved.

[0045] According to an aspect of the invention the retrofit concept includes a cylinder head - start valve assembly - fuel connection block -combination, comprising a cylinder head configured to close and seal a cylinder of an internal combustion piston engine, which cylinder head is provided with an air start valve cavity configured to receive an air start valve assembly comprising a start valve and a start valve extension part according to the invention, the aspects of which startvalve extension part being explained above, and a fuel ignitor cavity for assemble a fuel ignitor into the cylinder headwherein- a fuel feeding chamber is provided in the cylinder head, bordered by inner wall of the start valve cavity in the cylinder head, the first axially bordered interface area in outer wall of the start valve extension part, the first sealing arrangement and the second sealing arrangement, wherein the first sealing arrangement and the second sealing arrangement form a seal between the start valve extension part and the cylinder head, and wherein a fuel feeding channel is formed in the cylinder head which fuel feeding channel opens into the fuel feeding chamber, and extends between side wall of the cylinder head and the fuel ignitor cavity, - a leakage chamber is provided in the cylinder head, bordered by inner wall of the start valve cavity in the cylinder head, the second axially bordered interface area in outer wall of the start valve extension part, the second sealing arrangement and the third sealing arrangement, wherein the second sealing arrangement and the third sealing arrangement form a seal between the start air extension part and the cylinder head, and wherein a leakage channel is formed in the cylinder head, which leakage channel opens into the leakage chamber and extends between side wall of the cylinder head and the fuel ignitor cavity , - the third interface of the connection block is coupled with the cylinder head such that the fifth opening is in flow communication with fuel feeding channel in the cylinder head and the sixth opening is in flow communication with the leakage channel in the cylinder head.

[0046] The cylinder head - start valve assembly - fuel connection block - combination provides fuel delivery channel and leakage channel in the cylinder head which extend from side wall of the cylinder head to a fuel ignitor cavity in the cylinder head.

[0047] This way an internal combustion piston engine, comprising a cylinder head - start valve assembly - fuel connection block - combination according to the invention as described above is provided.

[0048] According to an aspect of the invention the retrofit concept includes a method of retrofitting a used cylinder head of an internal combustion piston engine, which used cylinder head comprisesa. a fuel injector cavity which extends through the cylinder head perpendicularly to a fire face of the cylinder head, in which fuel injector cavity a twin-needle liquid fuel injector is assembled,b. a start valve cavity which extends through the cylinder head, and which is parallel to the fuel injector cavity, in which start valve cavity an air start valve is assembled extending to the fire face of the cylinder head, and retained by a start valve extension part in the start valve cavity,c. a first transverse space extending from a side wall of the cylinder head to the fuel injector cavity, through which a first liquid fuel quill pipe is led from side of the cylinder head into contact with a fuel injector in the fuel injector cavity, d. a second transverse space extending from the side wall of the cylinder head to the fuel injector cavity, through which a second liquid fuel quill pipe is led from side of the cylinder head into contact with the fuel injector in the fuel injector cavity,wherein the method comprises disassembling• disassembling the first fuel quill pipe from the first transverse space • disassembling the second fuel quill pipe from the second transverse space• disassembling the twin-needle liquid fuel injector from the fuel injector cavity• the start valve extension part from the start valve cavityand• assembling a new fuel ignitor into the fuel injector cavity,• assembling a start valve extension part according to according to the invention into the start valve cavity in sealed manner, such thato the first transverse space forms a fuel feeding channel extending from the new fuel ignitor, via the start valve extension part, to open at a side wall of the cylinder head ando the second transverse space forms a leakage channel extending from the new fuel ignitor, via the start valve extension part, to a open at a side wall of the cylinder head such that the first transverse channel in the cylinder head forms a gas tight fuel feeding channel extending from thefuel ignitor, extending via the start valve extension part, to open at a side wall of the cylinder head and the second transverse channel forms a gas tight leakage channel extending from the fuel ignitor, via the start valve extension part, to a open at a side wall of the cylinder head,assembling a fuel connection block according to the invention by attaching to the cylinder head to connect the fuel feeding channel with fuel supply, and to connect the leakage channel to leakage handling system.

[0049] By means of the method according to the invention it is possible to convert an existing dual fuel engine, which uses liquid fuel as a pilot fuel into a fully gas operated engine.

[0050] Using the fuel connection block according to the invention conversion coupling of fuel channel and leakage channel is made simple and reliable, without a need of making changes to the cylinder head.

[0051] Advantageously in the method the engine is provided with fuel delivery and leakage handling system for a multi-cylinder internal combustion engine, comprising a number of fuel connection blocks according to the invention as described above, arranging the blocks as a group of successive fuel connection blocks wherein in each two successive fuel connection blocks the first one of the fuel connection blocks is in connection with the second one of the fuel connection blocks by a double wall pipe which is connected to one of the first and second interface in the first one of the fuel connection blocks, and to one of the first and second interface in the second one of the fuel connection blocks.

[0052] An internal combustion piston engine according to the invention comprises a fuel delivery and leakage handling system as disclosed above and a cylinder head - start valve assembly - fuel connection block - combination according to the invention as described above.

[0053] To combat global warming, several alternative fuels are being developed for use in large internal combustion piston engines. These fuels aim to reduce greenhouse gas emissions and dependence on fossil fuels. In this connection the following fuels are considered as the most prominent alternative fuels.Hydrogen can be used in internal combustion engines modified to burn hydrogen gas. It produces only water vapor as a byproduct, making it an attractive option for reducing greenhouse gas emissions. Ammonia can be used as a fuel in internal combustion engines, either directly or by cracking it into hydrogen. It is carbon-free, producing nitrogen and water as combustion byproducts. Methanol is an alcohol that can be produced from natural gas, biomass, or CO2 and hydrogen, methanol burns cleaner than conventional fuels.

[0054] In the context of the application the term pressurized fuel means fuel substantially at predetermined injection pressure and the term low pressure fuel means generally leakage fuel at lower pressure than the injection pressure and particularly fuel in a leakage line. In this context when relative expressions lower or upper is used, lower means closer to fire face of a cylinder head and upper means farther from the fire face in situation when assembled to cylinder head.

[0055] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.Brief Description of Drawings

[0056] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in whichFigure 1 illustrates a cylinder head suitable for use in a dual fuel engine,Figure 2 illustrates a start valve extension part for a cylinder head of a compressed air started internal combustion engine according to an embodiment of the invention,Figure 3 illustrates a start valve extension part for a cylinder head of a compressed air started internal combustion engine according to another embodiment of the invention,Figure 4 illustrates a fuel connection block according to an embodiment of the invention,Figure 5 illustrates views of connection interfaces of the fuel connection block of the figure 4,Figure 6 illustrates a fuel delivery and leakage handling system for a multi-cylinder internal combustion engine according to an embodiment of the invention,Figure 7 illustrates a cylinder head - start valve assembly - combination according to an embodiment of the invention,Figure 8 illustrates fuel ignitor according to an embodiment of the invention and.Figure 9 illustrates a cylinder head according to an embodiment of the invention.Detailed Description of Drawings

[0057] Figure 1 illustrates schematically a cylinder head 102 suitable for use in a so called dual fuel internal combustion piston engine, which is configured to combust liquefied natural gas (LNG) as its main fuel .which is ignited with a direct injection of liquid fuel as a pilot fuel, such as light fuel oil (LFO), and which is also provided with backup liquid fuel direct injection system for operating the engine with for example LFO as its main fuel instead of LNG. The cylinder head houses components like intake valves 104, one of which is shown here and exhaust valves (not shown), as well as a fuel injection valve 106. Typically, in an existing dual fuel engine, such as a Wartsila W50DF engine, has a centrally placed twinneedle injection valve 106 in each cylinder head 102 of the engine. The fuel injection valve 106 includes two injection needles. A larger needle 106.1 in the injection valve 106 is used in diesel mode for LFO operation, and a smaller needle 106.2 for pilot fuel injection when the engine is running in gas mode. The injection valve 106 is connected to two separate liquid fuel feedingsystems112,114 by means of quill pipes 116,118 which extend from side of the cylinder head to the fuel injection valve 106. A first quill pipe 118 is in fluid connection with the smaller needle and a second quill pipe 116 with the larger needle are both attached to the cylinder head. There are a first (lower) and a second (upper) transverse spaces 120,122 arranged to the cylinder head for assembling the quill pipes in the cylinder head 102, which spaces extend from the side wall to a cavity 124 for the fuel injection valve arranged to the cylinder head 102. A gas fuel admission valve 108, which is in connection with a gaseous fuel delivery rail 109 delivering gas for the cylinder in a line, is arranged in connection with combustion air inlet channel 110, such that gaseous fuel is admitted to combustion air prior to feeding into a combustion chamber in the engine. Admission of mixture of gaseous fuel and combustion air into a combustion chamber is controlled by the intake valves 104. The cylinder head 102 is further provided with an air start valve cavity 125 for an air start valve 126, and an air start air valve 126 arranged to the cavity 125. The air start valve is held at its position by an air start valve extension part 128, which is above the air start valve 126. The air start valve extension part 128 has transverse openings 130,132 for the quill pipes 116,118 to pass through the extension part 128. This kind of the cylinder head is advantageous as such for combustion of particularly LNG with ignition of direct injected LFO as pilot fuel, or alternatively in a diesel mode.

[0058] Aspects of the present invention will be described with reference to the Figures 2 to 9 which alone, or as a combination, results in advantageous effects in or facilitate conversion of an existing dual fuel engine into a more environmentally friendly internal combustion piston engine. An internal combustion piston engine according to the invention is capable of running with carbon free fuels and also ignition of the main fuel can be accomplished with the same single main fuel.

[0059] Figure 2 depicts schematically a start valve extension part 228 for a cylinder head 102 of a compressed air started internal combustion engine, according to an embodiment of the invention for use in retrofit conversion of a cylinder head of an internal combustion piston, particularly as shown in the figure 1. In the following the start valve extension part 228 will be called simply as an extension part for sake of simplicity. The extension part 228 has a rotationally symmetrical body 230 which has a central longitudinal axis A and a first axial end232 and a second axial end 234. When assembled to a cylinder head the first end 232 is against a start air valve. The extension part 228 is configured to retain a start air valve in the cylinder head. On outer surface of the extension part 228 there is formed a first axially bordered interface area 235, which is bordered by a first sealing arrangement 238 and a second sealing arrangement 240 in circumference of the body 230. There is also a second axially bordered interface area 236 on outer surface of the body 230, bordered by the second sealing arrangement 240 and a third sealing arrangement 242 in circumference of the body. The interface areas are substantially cylindrical. The sealing arrangements comprises preferably an annular groove on the body and resilient sealing rings, such as O-rings, arranged to the grooves.

[0060] The interface areas are configured to form gas tight spaces within a start valve cavity in the cylinder head when assembled, which belong to fuel feeding channel system of the engine after conversion of an existing dual fuel engine. The first axially bordered interface 235 is a lower axially bordered interface, and second axially bordered interface 236 is an upper axially bordered interface. The lower axially bordered interface area partly forms or borders a fuel feeding line in the cylinder head. The upper axially bordered interface area partly forms or borders a leakage line in the cylinder head. The leakage line is provided for safely collect e.g. possible fuel leakage in the fuel feeding line and / or fuel injector.

[0061] There is a first fluid channel 243 which is arranged at a first longitudinal position in the extension part extending across the extension part 228, which first fluid channel is arranged to the first axially bordered interface area 235. The first fluid channel 243 in the extension part 228 will be connected in gas tight manner to the lower transverse channel 122 in the cylinder head during retrofit conversion. The extension part 228 is also provided with a second fluid channel 244 which is arranged to the second axially bordered interface area 236 at a second longitudinal position in the extension part extending across the extension part. The second fluid channel 244 in the extension part 228 will be connected in gas tight manner to the upper transverse channel 120 in the cylinder head during retrofit conversion.

[0062] In the embodiment shown in the figure 2 both the first and the second fluid channels 244,243 comprise a transverse through hole, such as a boring, inthe body 230. The holes are parallel to each other and perpendicular to longitudinal axis A of the extension part. The transverse through holes are preferably in the middle of radial cross section to the body so as to smoothly connect with the transverse channels 120,122 in the cylinder head. The transverse channels 120,122 in the cylinder head which before conversion are used as spaces for quill pipes will be converted into fuel flow channels in the conversion. The first sealing arrangement 238 is at the first axial end 232 of the extension part 228, that is the end in proximity with a start air valve, when assembled to the cylinder head. The first sealing arrangement comprises two separate seals, a first seal 238.1 and a second seal 238.2 arranged at axial distance from each other, and circumscribing an outer surface of the body 230. Preferably the seals in the first sealing arrangement comprise two annular grooves on the body and resilient sealing rings, such as O-rings, arranged to the grooves.

[0063] There is an axial gap, or a predetermined distance, between the seals 238.1, 238.2 such that a leak detection area is formed between the seals 238.1, 238.2. The body 230 is provided with an internal channel 246 which extends from the axial gap between the seals 238.1, 238.2 to the second fluid channel 224. The internal channel 246 is a leakage fluid channel for conveying fluid from the axial gap to the second fluid channel 224. Such fluid can be entered to the gap due to failure of either one of the seals 238.1 , 238.2. Axial distance between the seals 238.1 , 238.2 is preferably less than 1 ,5 times width of one of the grooves. This way the space between the seals is considerably small and thus any leakage through the seals will not be unnecessarily accumulated in the space.

[0064] As it can be seen in the figure 2, in this embodiment the internal channel 246 comprises an axial boring section 246.1 which extend from a first end of the body 232 to the second fluid channel 224, and a radial boring section 246.2, which extends from the axial gap to the axial boring section 246.1. Further the axial boring section 246.1 is plugged by a plug 246.3 at its end at the first end of the body. Even if this is considered to be the most feasible way of providing the internal channel 246 to connect the axial gap between the seals to the second fluid channel, there are also alternative routes for the channel. Because the purpose of the internal channel is to lead leakage fluid from the gap eventually to the transverse channel 120 of the cylinder head 102, the internal channel can bearranged to extend between the axial gap between the seals 238.1, 238.2 to outer surface of the body 230 withing the second axially bordered interface area 236, even if not shown here.

[0065] Figure 3, which discloses a start valve extension part 228 according to another embodiment of the invention, depicts an alternative implementation compared to figure 2 of the first and / or second fluid channel 243’, 244’ which is arranged to extend transversely across the extension part 228. In the figure 3 both of the first and the second fluid channels 243’, 244’ comprise a recess, within respective axially bordered interface area 235,236 on outer surface of the body 230, which recess extends across the body in transverse direction. In the figure 3 the recesses are annular or circumferential grooves. Such grooves extend over at least half of the circumference. Functionally a core function of the fluid channel is to provide a flow connection for the transverse channels 120, 122 in the cylinder head 102. Actual form of the recess may vary within the core function of the fluid channel. It should be understood that only one or both of the through holes 244,243 shown in the figure 2 may be replaced with a recess on the outer surface of the body, as depicted in the figure 3. Additionally, a combination of features in the figures 2 and 3 may be feasible in some practical applications, such that both a through hole and a recess is provided within an axially bordered interface area.

[0066] Preferably the first fluid channel 243, 243’ has smaller cross-sectional area than the second fluid channel 224,224’, and the first fluid channel is closer to the first axial end of the start valve extension part. In the figure 3 there is also depicted how the internal channel 246 extends from the axial gap between the seals 238.1 , 238.2 to the recess 224’ to outer surface of the body 230 withing the second axially bordered interface area 236.

[0067] Cross-sectional area of the second fluid channel 244,244’ is at least 1 ,5 times larger than the first fluid channel 243,243’, advantageously 2 - 10 times larger. This way second fluid channel provides adequate flow area for possible fluid leakage.

[0068] The extension part 228 according to the invention makes it possible to convert the spaces 120,122 originally made for quill pipes into flow channels for fuel and leakage fluid in the cylinder head 102.

[0069] The extension part may be used particularly in retrofit conversion of a cylinder head shown in the figure 1 in combination with a fuel connection block attached to the cylinder head.

[0070] Figure 4 depicts schematically fuel connection block 300 according to an embodiment of the invention. The fuel connection block 300 is configured to connect a coaxially configured fuel feed channel 302 - leakage channel 304 combination together forming a fuel line 600, preferably a double wall pipe 602, to a cylinder head 102 of an internal combustion piston engine. The connection block is generally a substantially cuboid block, which has three interfaces: first inter-face308 four coupling a first fuel line to the connection block 300, and a second interface 310 for coupling a second fuel line to the connection block 300 and a third interface 306 for coupling the connection block 300 to the cylinder head 102. At least the third interface has a planar interface surface which is configured to mate with a counter surface in the cylinder head, but preferably the first, the second and the third interface all have a planar interface surface. The interface surfaces are disclosed in the figure 5 as views A, C and C. The third interface is shown in the view A, the first interface is shown in the view B and the second interface is shown in the view C.

[0071] With a reference to the figure 4 and figure 5 the first interface, shown in the view B, comprises a first opening 514 for fuel feed line and a second opening 516 for leakage line. The first interface 308 is provided with a first groove 518 for a first sealing ring 520 arranged to the first interface. There is also a second groove 522 for a second sealing ring 524 arranged to the first interface 308. As it can be seen, the first opening is inside both of the first groove 518 and the second groove 522. The first opening 514 is circumscribed only by the first groove 518. Both of the grooves and the sealing rings are continuous such that there is a single seal formed for the second opening 516 and a double seal formed for the first opening 514. The first groove 518 and the second groove 522 are substantially concentric with the first opening 514 which is of circular cross section, and the second opening 516 is arranged in an annular space between the first and the second groove. Should the first sealing leak the second sealing will prevent leakage out and direct the leakage flow to the second opening.

[0072] The second interface 310 comprises respectively a third opening 526 for fuel feed line and a fourth opening 528 for leakage line. There is a third groove 530 for a third sealing ring 532 arranged to circumscribe the third opening 526 and the fourth opening 528. A fourth groove 534 for a fourth sealing ring 536 is arranged to the second interface 310 inside the third groove 530, the fourth groove 534 circumscribing only the third opening 526. Both of the grooves 530,534 and the sealing rings 532,536 are continuous such that there is a single seal formed for the fourth opening 528 and a double seal formed for the third opening 526. The openings are preferably of circular cross section. The third groove 530 and the fourth groove 534 are substantially concentric with the third opening 526 which is of circular cross section, and the fourth opening 528 is arranged to annular space between the third and the fourth groove. Should the third sealing leak the fourth sealing will prevent leakage out and direct the leakage flow to the fourth opening.

[0073] The third interface 306, shown in the view A, comprises a fifth opening 502 for fuel feed line and a sixth opening 504 for leakage line. There is a fifth groove 506 for a fifth sealing ring 508 arranged to the third interface 305 to circumscribe the fifth opening 502 and the sixth opening 504. The fifth groove 506 is shown in the figure 5 with a resilient sealing ring 508 arranged to the groove, but in the figure 4 the groove is shown without a sealing ring for clarity reasons. Both the fifth and sixth opening 502,504 are inside the fifth groove 506. The fifth groove and thus the respective sealing ring therefore fully circumscribe both openings. There is a sixth groove 510 arranged to the third interface 306 of the fuel connection block 300 for a sixth sealing ring 512. The sixth groove 510 and the sixth sealing ring 512 circumscribes only the fifth opening 502. Thus, the sixth groove 510 is inside the fifth groove 506. Both of the grooves and the sealing rings are continuous such that there is a single seal formed for the sixth opening 504 and a double seal formed for the fifth opening 502. Should the fifth sealing leak the fourth sealing will prevent leakage out and direct the leakage flow to the fourth opening.

[0074] The fuel connection block comprises further a first channel system 538 for pressurized fuel which is arranged inside the fuel connection block 200 fluidlyconnecting the fifth opening 502, the first opening 514 and the third opening 526 with each other such that a free flow connection between the openings is formed.

[0075] There is also arranged a second channel system 550 for leakage fuel which is arranged inside the fuel connection block 300 extending between the sixth opening 504, the second opening 516 and the fourth opening 528 with each other.

[0076] This way the fuel connection block 300 is configured to connect a fuel feed channel and leakage channel between respective openings in the first, the second and the third interface 306,308,310. The third interface 306 is configured to mate with the transverse channels’ 120,122, attachment means and attachment surface in the cylinder head 102.

[0077] Now turning to view A in the figure 5, the openings in the third interface 306 are preferably at a distance from each other which is 4 - 9 x diameter of the second opening 504. The fifth groove 506 goes around both of the fifth and the sixth openings and therefore it is generally of elongated rectangular shape. It has two semi-circular end sections 540,542 and two parallel groove sections 546, 548 connecting the end sections. The fifth opening 502 is at, or in a region of, a center of a first semi-circular end section 540 and the sixth opening 504 is at, or in a region of, a center of a second semi-circular end section 542. The sixth groove 510 is a circular groove being substantially concentric with and in proximity to the first semi-circular end section 540, and the fifth opening 502 is of circular cross section and is substantially concentric with the sixth groove 510.

[0078] The fuel connection bock 300 shown in the figure 4 is configured to convey fuel from one cylinder head to another, which is more specifically disclosed in the figure 6. By means of the connection block it is possible to connect fuel channels of successive cylinders with each other and to fuel delivery system as well as connect leakage channels of successive cylinders with each other and to leakage handling system. In order to transfer fuel between several cylinder heads the first channel system 538 comprises a primary flow connection 538.1 , depicted by a dashed line with arrows, between the first opening 514 and the third opening 526. The fifth opening 502 is connect to the primary flow connection 538.1 via a secondary flow connection 538.2. Cross-sectional area of the primary flowconnection 538. 1 is at least 5 times greater than the cross-sectional area of the secondary flow connection 538.2 which provides effective fuel delivery to the cylinder head to which the fuel connection block 300 is connected by the third interface 306 and also to other cylinder heads connected via the fuel connection block 300.

[0079] The fuel connection block 300 is also configured to lead possible leakage fluid from the cylinder head, and for conveying leakage fluid from anyone of several cylinder head connected with each other to further processing the leakage safely. Compared to the fuel flow rate the leakage is considerably smaller and therefore cross-sectional area of the second 516 and fourth openings 528 is 0,2 - 0,5 times cross sectional area of the first 514 and third 526 openings in the fuel connection block 300. Respectively a mean cross-sectional area of the first channel system 538 is preferably 2 to 5 times larger than mean cross-sectional area of the second channel system 550.

[0080] Further, in the figure 4 there is disclosed that the fuel connection block 300 may, as an advantageous, but not essential, further development, be provided with a closing valve 320. The closing valve 320 is arranged in in the second channel system 550 in connection with the sixth opening 504 in the third interface 306 of the fuel connection block 300. The closing valve 320 is pressure actuated such that when pressure in the upper transverse channel 120 of the cylinder head, and therefore also in the sixth opening 504 is increased higher than a predetermined threshold pressure, the leakage fluid pushes a closing element 322 so as to open the valve 320. The closing valve 320 comprises an inlet 324, which is here in direct connection with the sixth opening 504. More precisely, the inlet 324 of the closing valve is solely in flow connection with the sixth opening 504 in the third interface 306. The closing valve 320 comprises also an outlet 326, which outlet 326 of the closing valve is in flow connection with both the second opening 516 and the fourth opening 528 via the second channel system 550.

[0081] The closing element 322 is arranged movably between a first position at which the closing element closes flow connection between the inlet 324 and the outlet 326, and a second position at which the closing element opens flow connection between the inlet 324 and the outlet 326. The closing element 322 is configured to open by effect of fluid pressure at the inlet 324 of the closing valve 320.When pressure in the inlet 324 is greater than a predetermined threshold pressure the closing element changes its position, i.e. moves axially, from the first position to the second position. The closing element 322 is preferably a piston or alike. The piston is arranged to the closing valve such that that there is a predetermined threshold pressure which needs to be exceeded before the piston start to move. Should there be a counter pressure in the second channel system 550 the threshold pressure should be understood as a threshold pressure difference. The piston partly extends out from the fuel connection block 300 in the first interface 308. Since the piston is arranged to move axially when pressure increases in the inlet 3251 the second opening 504 over the predetermined threshold pressure, a part extending out from the fuel connection block indicates at least visually a leakage in fluid system of the cylinder head. Even if the second channel system 550 may be connected via the second opening 516 or the fourth opening 528 a remote leakage detector, the piston end popped out from the fuel connection block 300 reveals a cylinder head in which leakage occurs.

[0082] As it is depicted by dashed line the second channel system 550 preferably comprises a parallel extension channel system 550’ system for increasing cross sectional flow area of the second channel system, which in turn decreases flow resistance of leakage fluid and improves leakage detecting operation. The extension channel system connects the outlet 326 of the closing valve 320 to the space between the first groove 518 and the second groove 522 in the first interface 308 and space between third groove 530 and fourth groove 534 in the second interface 310.

[0083] The fuel connection blocks 300 can be used in conversion of an existing dual fuel engine into a more environmentally friendly internal combustion piston engine such that fuel delivery into each cylinder of the engine and safe and reliable handling of possible leakage is ensured. Figure 6 discloses a fuel delivery and leakage handling system 600 for a multi-cylinder internal combustion piston engine according to an embodiment of the invention. The fuel delivery and leakage handling system is intended for connecting cylinder heads in line successively with each other. When using the system, the cylinder heads of a piston engine are provided with a fuel connection block 300, as disclosed in and with reference to the figure 4, attached to each cylinder head 102 of the engine. Theconnection blocks 300 are coupled with each other as a group of successive fuel connection blocks by fuel lines 600, such that in each two successive fuel connection blocks 300. n, 300. n+1 in respective successive cylinder heads 102. n, 102. n+1 the first one of the fuel connection blocks 300. n in the first one of the cylinder heads 1O2.n is in connection with the second one of the fuel connection blocks 300. n+1 in the second one of the cylinder heads 102. n+1 by the fuel line 600. The fuel line comprises a double wall pipe 602. The double wall pipe 602, which comprises an inner pipe and outer pipe providing central flow channel for fuel and annular flow channel for leakage fluid, is connected to one interface 308 of the first and second interface 308,301 in the first one of the fuel connection blocks 300. n, and to one interface 310 of the first and second interface 308,310 in the second one of the fuel connection blocks 300. n+1. This way the fuel delivery and leakage handling system connect the cylinder heads successively to each other, i.e. one after the other. The double wall pipe has a connector at its both end which are compatible with the first and second interface 308,310 of the fuel connection block 300, such that the first opening 514 and the third opening 526 is in connection with the central flow channel of the double wall pipe 602 and the second opening 516 and fourth opening 528 are in connection with the annular flow channel. In V-engines the cylinder heads of a bank form an in-line configuration where the cylinders heads are connected with each other by means of the system preferably such that in the system - independently on number or configuration of the cylinders - can have only one connection to fuel supply 604 and leakage handling system 606.

[0084] Figure 7 discloses a cylinder head - start valve assembly - combination 800 according to the invention. The combination is preferably obtained by a retrofit method which will be explained later. The cylinder head - start valve assembly - combination 800 comprises a cylinder head 102 configured to close and seal a cylinder of an internal combustion piston engine. The cylinder head 102 is similar to the cylinder head disclosed in the figure 1. The cylinder head 102 is provided with an air start valve cavity 125 configured to receive an air start valve assembly. The cylinder head is provided with a cavity 104 which originally is configured to receive a fuel injection valve 106. After of during a retrofit conversion according to the invention the cavity 104 in the cylinder head will be designated as a fuel ignitor cavity. A start air valve assembly in the cylindercomprises a start valve 126 and a start valve extension part 228. The start valve extension part 228 according to the invention provides significant contribution to the retrofit method according to the invention. In the figure 7 the air start valve 126 is shown in very schematic manner. The air start valve extension part 228 according to the invention which is assembled to the cylinder head 102 is disclosed in more detailed manner in the figures 2 and / or 3. The upper and lower transverse spaces 120,122 arranged in the cylinder head which are originally spaces for quill pipes, are converted into a first and a second transverse flow channels The cylinder head - start valve assembly - combination 800 provides an advantageous solution to deliver fuel to a gaseous fuel ignitor 10 which is configured to provide source of ignition for gaseous fuel in a mixture of charge air and fuel.

[0085] For feeding fuel to such ignitor 10, a fuel feeding chamber 802 is provided in the cylinder head, bordered by inner wall of the start valve cavity 125 in the cylinder head, the first axially bordered interface area 235 (see figure 2 or 3 for features of the extension part 228) in outer wall of the start valve extension part 228, the first sealing arrangement 238 and the second sealing arrangement 240, wherein the first sealing arrangement 238 and the second sealing arrangement 240 form a seal between the start valve extension part 230 and the cylinder head 102, and wherein a fuel feeding channel is formed from the first transverse space 122 in the cylinder head and the fuel feeding channel 122 opens into the fuel feeding chamber 802, and extends between side wall of the cylinder head and the fuel ignitor cavity 124.

[0086] Additionally, a leakage chamber 804 is provided in the cylinder head such that it is bordered by inner wall of the start valve cavity 125 in the cylinder head, the second axially bordered interface area 236 in outer wall of the start valve extension part 228, the second sealing arrangement 240 and the third sealing arrangement 242, wherein the second sealing arrangement 240 and the third sealing arrangement 242 form a seal between the start air extension part 228 and the cylinder head 102, and wherein a leakage channel is formed from the second transverse space 120 in the cylinder head 102 which leakage fluid channel opens into the leakage chamber, and extends between side wall of the cylinder head and the fuel ignitor cavity 124.

[0087] As a further development, a fuel connection block 300 according to the invention is attached to side wall of the cylinder head 102. The fuel connection block is disclosed in more detailed manner in the figures 4 and 5. The third interface 306 of the fuel connection block is coupled with the cylinder head such that the first opening 502 is in flow communication with fuel feeding channel 122 in the cylinder head and the second opening 504 is in flow communication with the leakage channel 120 in the cylinder head. This way fuel maybe fed via the fuel connection block 300 to the fuel ignitor 10 and leakage fluid maybe conveyed from the cylinder head to further processing.

[0088] As a still further development, in the conversion the cylinder head is preferably provided with a fuel ignitor 10, and thus the cylinder head - start valve assembly - combination according to the invention comprises a fuel ignitor 10 which is disclosed in more detailed in PCT / EP2024 / 066248, which is incorporated as reference. Such a fuel ignitor 10 makes it possible to utilize conversion of spaces for quill pipes in an existing cylinder head into fuel and leakage fluid channels in full effect. However, as a minimum requirement the fuel ignitor, which also the ignitor disclosed in the PCT / EP2024 / 066248 fulfils, the ignitor 10 has outer form which is compatible with the fuel injector cavity 125 in the cylinder head and it has fuel inlet arranged axially corresponding the location of the fuel feeding channel and leakage outlet arranged axially corresponding to the location of the leakage channel in the cylinder head. Such a compatible fuel ignitor 10 is shown in the figure 8. Next, fluid interfaces of the ignitor 10 with fluid channels of a cylinder head 102, to which the ignitor is configured to be installed, will be discussed in following. The interfaces are formed to an outer wall of the ignitor 10 and they communicate differently with ignitor 10. The ignitor 10 comprises separate interface areas 14.1,14.2,14.3 in its axial direction, that is, in the direction of the longitudinal axis A of the ignitor 10. The ignitor is provided with sealing arrangements 16.1, 16.2, 16.3, 16.4 which border the interface areas in axial direction and fluidly separate them from each other. There are three axially bordered interface areas 14.1,14.2,14.3 on outer surface of the body assembly 12, bordered by four sealing arrangements. The sealing arrangement are arranged to circumscribe the body assembly and so also an interface area circumscribes the body assembly 12. The sealing arrangement are in fluid tight connection withcounter surfaces in the cylinder head, when the ignitor 10 is assembled correctly to a cylinder head. The first interface area 14.1 is configured forexchanging coolant with the ignitor 10 and the cylinder head, the second interface area 14.2 is configured for feeding gaseous fuel to the ignitor and the third interface area 14.3 is configured for leading possible leakage gas from the ignitor.

[0089] The first interface area 14.1 at a region of the prechamber 12. The first interface 14.1 is bordered by a first sealing arrangement 16.1 at the prechamber and by a second sealing arrangement 16.2 at opposite axial end of the first interface 14.1. The first sealing arrangement 16.1 is arranged to a prechamber part 12.1 of the ignitor 10 and the second sealing arrangement 16.2 is arranged axially at a distance from the prechamber part 12.1. The first sealing arrangement 16.1 comprises a radial sealing surface in the prechamber part 12.1 facing downwards towards the tip of the prechamber. The second sealing arrangement comprises two grooves 16.2’, 16.2” arranged to circumscribe outer wall of the ignitor body assembly configured for use of a resilient ring seal, such as an O-ring. The two grooves are preferably similar.

[0090] The second interface area 14.2 is arranged next to, and upper than the first interface area 14.1, bordered by the second sealing arrangement 16.2 and a third sealing arrangement 16.3. The second interface area 14.2 extends radially from the second sealing arrangement 16.2 to the third sealing arrangement 16.3. The second interface 14.2 is configured for feeding gas to the ignitor, and therefore the ignitor 10 is provided with fuel inlet within the region. When installed to the cylinder head it is in flow communication with the fuel feeding channel 122 in the cylinder head 102.

[0091] The third interface 14.3 is arranged next to and upper than the second interface area 14.2. The third interface area 14.3 extends axially from the third sealing arrangement 16.3 to the fourth sealing arrangement 16.4, which borders axially the third interface 14.3. The third sealing arrangement and the fourth sealing arrangement both comprise one groove arranged to circumscribe outer wall of the ignitor body assembly configured for use of a resilient sealing ring. The third interface are 14.3 is configured for leading leakage, such leaked fuel gas away from the ignitor and / or for detecting a possible gas leakage, and therefore the ignitor is provided with leakage outlet within the region. When installed to thecylinder head the third interface 14.3 is in flow communication with the fuel feeding channel 122 in the cylinder head 102. There is a detection opening 34.1 arranged between the grooves 16.2’, 16.2” for a leakage flow channel 34 extending from an inlet opening 34.1 between the two groovesl 6.2’, 16.2” to the third interface 14.3.

[0092] An existing or a use cylinder head of, particularly such as is disclosed in the figure 1, an internal combustion piston engine, is retrofitted as explained in the following. Even if here the method is explained with reference to one cylinder head, all of the cylinder heads in an engine are converted making use of the method. As is disclosed in the figure 1 an existing cylinder head comprises a. a fuel injector cavity 124 which extends through the cylinder head 102 perpendicularly to a fire face of the cylinder head, in which fuel injector cavity a twin-needle liquid fuel injector is assembled,b. a start valve cavity 125 which extends through the cylinder head 102, and which is parallel to the fuel injector cavity 124, in which start valve cavity an air start valve 126 is assembled extending to the fire face of the cylinder head, and retained by a start valve extension part 128 in the start valve cavity,c. a first transverse space 122 extending from a side wall of the cylinder head 102 to the fuel injector cavity 124, through which a first liquid fuel quill pipe 118 is led from side of the cylinder head into contact with a fuel injector 106 in the fuel injector cavity,d. a second transverse space 120 extending from the side wall of the cylinder head 102 to the fuel injector cavity 124, through which a second liquid fuel quill pipe 116 is led from side of the cylinder head into contact with the fuel injector 106 in the fuel injector cavity.The existing dual fuel internal combustion piston engine is converted into fully gas operated engine, the method comprising at least the following steps:• disassembling the first fuel quill pipe 118 from the first transverse space 122• disassembling the second fuel quill pipe 116 from the second transverse space 120• disassembling the twin-needle liquid fuel injector 106 from the fuel injector cavity 124• disassembling the start valve extension part 128 from the start valve cavity 125and, explained with reference to the figure 7• assembling a new fuel ignitor 10 into the fuel injector cavity 124 in sealed manner,• assembling a new start valve extension part 228, which is of type disclosed in more detailed in the figures 2 and / or 3 into the start valve cavity 125 in sealed manner, such that the first transverse channel 122 in the cylinder head forms a gas tight fuel feeding channel extending from the new fuel ignitor 10, extending via the start valve extension part 228, to open at a side wall of the cylinder head and the second transverse channel 120 forms a gas tight leakage channel extending from the new fuel ignitor 10, via the start valve extension part 228, to a open at a side wall of the cylinder head,and assembling a fuel connection block according to the invention by attaching to the cylinder head to connect the fuel feeding channel with fuel supply, and to connect the leakage channel to leakage handling system.

[0093] As it can be seen in the figure 7 fuel feeding channel and the leakage channel extend from fuel ignitor cavity 124 to the start valve cavity 125 and from the start valve cavity 125 to side wall of the cylinder head 102. The channels 120,122 after conversion uses surface of the cylinder head as a surface of actual flow channel. The sealings 238,240,242, the interface areas 235,236 and the fluid channels 243, 244 in the extension part 228 (see figure 2 and 3) result in gas tight flow path between the sections of the channels at both sides of the start valve cavity 125.

[0094] Figure 9 discloses a cylinder head 102’ according to an aspect of the invention. Like the cylinder head 102 shown in the figure 1 the cylinder head 102’ houses components like intake valves 104, as well as a fuel ignitor 10. The fuel ignitor 10 is connected to the upper and the lower transverse spaces 120,122 arranged in the cylinder head. In the cylinder head 102’ there are channels which belong to a fuel delivery and leakage handling system for connecting a fuel feed line and a leakage fluid line in a cylinder head and multiple cylinder heads in an internal combustion piston engine, comprising first interface 308 in connection with the cylinder head 102’ for coupling a first fuel line 600 to the cylinder head102’, a second interface 310 in connection with the cylinder head 102 for coupling a second fuel line 600 to the same cylinder head 102’. The first interface and the second interface in the cylinder head 102’ correspond to the first interface and the second interface in the connection block 300 and therefore connectors of the fuel line are suitable for use in both the connection block and cylinder head 102’ shown in the figure 9.

[0095] The first interface 308 in the cylinder head 102’ comprises a first opening 514 for fuel feed line and a second opening 516 for leakage line, both openings being circumscribed by a first groove 518 for a first sealing ring arranged to the first interface 308, wherein a second groove 522 for a second sealing ring is arranged to the first interface 308 inside the first groove 518 circumscribing only the first opening 514, The second interface 310 comprises a third opening 526 for fuel feed line and a fourth opening 528 for leakage line, both openings being circumscribed by a third groove 530 for a third sealing ring arranged to the second interface 310, wherein a fourth groove 534 for a fourth sealing ring is arranged to the second interface 310 inside the third groove 530 circumscribing only the third opening 526, The cylinder head 102’ further comprises a first channel system 538 for pressurized fuel in connection with the cylinder head 102’ fluidly connecting a fuel feeding channel 120 in the cylinder head, the first opening 514 and the third opening 526 with each other and a second channel system 550 for leakage fluid in connection with the cylinder head 102 extending between a leakage line in the cylinder head 102’, second516) and the fourth opening 528.

[0096] As it becomes clear the cylinder head 102’ provides a functionality of the fuel connection block integrated into the cylinder head. The first and the second interfaces in the cylinder head 102’ are similar to those of the connection block explained in the figure 5. All the features, except those concerning the third interface, are similar to the disclosure of figures 4 and 5.

[0097] Figure 9 also discloses an aspect of the invention where the fuel connection system in the cylinder head 102’ is provided with a closing valve 320 in the second channel system 550, which comprises an inlet 324, which inlet of the closing valve is solely in flow connection with the fuel feed line in the cylinder head 102’, and an outlet 326, which outlet of the closing valve is in flow connection with both the second opening 516 in the first interface and the fourth opening528 in the second interface and a closing element 322 such as a piston, which is arranged axially movably between a first position at which the closing element closes flow connection be-tween the inlet 324 and the outlet 326, and a second position at which the closing element 322 opens flow connection between the inlet and the outlet. The closing element 322 is configured to open when pressure in the inlet 324 is greater than a threshold pressure which needs to be exceeded before the closing element changes its position from the first position to the second position.

[0098] More precisely the closing element 322 is a piston assembly, one end of which extending out from the fuel connection block 300 for visual indication of position of the closing element 322.

[0099] The cylinder head 102’ can be used in a fuel delivery and leakage handling system for a multi-cylinder internal combustion engine where a number of cylinder heads 102’ in cylinders of an internal combustion engine are arranged as a group of successive cylinder heads 102’ similarly as is described in the figure 6 for an embodiment where in retrofit conversion existing cylinder heads are used and which are provided with a connection block for coupling the cylinder heads with each other. A fuel delivery and leakage handling system can be provided by making use of cylinder heads shown in the figure 9 and following the disclosure of the figure 6 such that in each two successive cylinder heads 102’ the first one of the cylinder heads 102’is in connection with the second one of the cylinder heads 102’by a double wall pipe 602, which is connected to one of the first and second interface 308, 310 in the first one of the cylinder heads and to one of the first and second interface 308,310 in the second one of the cylinder heads.

[0100] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is obvious to the skilled person that, along with the technical progress, the basic idea of the invention can be implemented in many ways. The invention and its embodiments are thus not limited to the examples and samples described above but they may vary within the contents of patent claims and their legal equivalents. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.

Claims

33Claims1. A fuel delivery and leakage handling system for connecting a fuel feed line and a leakage fluid line in a cylinder head, and multiple cylinder heads (102,102’) in an internal combustion piston engine, comprising- first interface (308) in connection with the cylinder head (102,102’) for coupling a first fuel line (600) to the cylinder head (102,102’),- a second interface (310) in connection with the cylinder head (102,102’) for coupling a second fuel line (600) to the same cylinder head (102, 102’), wherein- first interface (308) comprising a first opening (514) for fuel feed line and a second opening (516) for leakage line, both openings being circumscribed by a first groove (518) for a first sealing ring arranged to the first interface (308), wherein a second groove (522) for a second sealing ring is arranged to the first interface (308) inside the first groove (518) circumscribing only the first opening (514),- the second interface (310) comprising a third opening (526) for fuel feed line and a fourth opening (528) for leakage line, both openings being circumscribed by a third groove (530) for a third sealing ring arranged to the second interface (310), wherein a fourth groove (534) for a fourth sealing ring is arranged to the second interface (310) inside the third groove (530) circumscribing only the third opening (526),and further comprising- a first channel system (538) for pressurized fuel in connection with the cylinder head (102) fluidly connecting a fuel feeding channel (120) in the cylinder head, the first opening (514) and the third opening (526) with each other,- a second channel system (550) for leakage fluid in connection with the cylinder head (102,102’) extending between a leakage line in the cylinder head (102,102’) second opening (516) and the fourth opening (528).

2. A fuel delivery and leakage handling system according to claim 1, characterized in that fuel connection system is provided with a closing valve (320) in the second channel system (550), which comprises34- an inlet (324), which inlet of the closing valve is solely in flow connection with the fuel feed line in the cylinder head (102), and- an outlet (326), which outlet of the closing valve is in flow connection with both the second opening (516) in the first interface and the fourth opening (528) in the second interface,- a closing element (322), such as a piston, which is arranged axially movably between a first position at which the closing element closes flow connection between the inlet (324) and the outlet (326), and a second position at which the closing element (322) opens flow connection between the inlet and the outlet, wherein the closing element (322) is configured to open when pressure in the inlet (324) is greater than a threshold pressure which needs to be exceeded before the closing element changes its position from the first position to the second position.

3. A fuel delivery and leakage handling system according to claim 2, characterized in that the closing element (322) is a piston assembly, one end of which extending out from the fuel connection block (300) for visual indication of position of the closing element (322).

4. A fuel delivery and leakage handling system according to anyone of the preceding claims 1 to 3 characterized in that a number of cylinder heads (102) in cylinders of an internal combustion engine are arranged as a group of successive cylinder heads (102) wherein in each two successive cylinder heads (1O2.n, 102. n+1) the first one of the cylinder heads (102. n) is in connection with the second one of the cylinder heads (102. n+1) by a double wall pipe (602), which is connected to one of the first and second interface (308, 310) in the first one of the cylinder heads and to one of the first and second interface (308,310) in the second one of the cylinder heads.

5. A fuel delivery and leakage handling system according to claim 4, characterized in that the system comprises a fuel connection block according to anyone of the claims 6 to 13 removably attached to each cylinder head, through which the fuel feed line in the cylinder head is connected to the first fuel line and the second fuel line (600), wherein the fuel connection blocks (300) are arranged as a group of successive fuel connection blocks (300) wherein in each twosuccessive fuel connection blocks (300. n, 300n+1) the first one of the fuel connection blocks (300. n) is in connection with the second one of the fuel connection blocks (300. n+1) by a double wall pipe (602), which is connected to one of the first and second interface (308, 310) in the first one of the fuel connection blocks (300. n), and to one of the first and second interface (308,310) in the second one of the fuel connection blocks (300. n+1).

6. A fuel connection block for connecting a fuel feed line and a leakage fluid line in a cylinder head (102), between multiple cylinder heads (102) in an internal combustion piston engine, comprising- a first interface (308) in the cylinder head (102) for coupling a first fuel line (600) to the cylinder head (102),- a second interface (310) in the cylinder head (102) for coupling a second fuel line (600) to the cylinder head (102,- a third interface (306) for coupling the connection block (300) to the cylinder head (102),wherein- the first interface (308) comprising a first opening (514) for fuel feed line and a second opening (516) for leakage line, both openings being circumscribed by a first groove (518) for a first sealing ring arranged to the first interface (308), wherein a second groove (522) for a second sealing ring is arranged to the first interface (308) inside the first groove (518) circumscribing only the first opening (514),- the second interface (310) comprising a third opening (526) for fuel feed line and a fourth opening (528) for leakage line, both openings being circumscribed by a third groove (530) for a third sealing ring arranged to the second interface (310), wherein a fourth groove (534) for a fourth sealing ring is arranged to the second interface (310) inside the third groove (530) circumscribing only the third opening (526),- the third interface (306) has a planar interface surface comprising a fifth opening (502) for fuel feed line and a sixth opening (504) for leakage line, both openings being circumscribed by a fifth groove (506) for a fifth sealing ring arranged to the third interface (306), wherein a sixth groove (510) for a sixth sealing ring is arranged to the third interface (306) inside the fifth groove (506), circumscribing only the fifth opening (502),and further comprising- a first channel system (538) for pressurized fuel in the connection block, fluidly connecting, the first opening (514) and the third opening (526), and the fifth opening (502) with each other,- a second channel system (550) for leakage fluid in the connection block extending between the second opening (516) and the fourth opening and sixth opening (504).

7. A fuel connection block (300) according to claim 6, characterized in that the fifth groove (506) is of elongated rectangular shape with two semi-circular end sections and two parallel groove sections connecting the end sections, and that the sixth groove (510) is a circular groove in proximity to one of the semicircular ends, and that the fifth opening (502) is of circular cross section and is concentric with the sixth groove (510).

8. A fuel connection block (300) according to claim 6 or 7, characterized in that in the fifth opening (502) and the sixth opening (504) are of circular cross section and distance between the fifth opening (502) and the sixth opening (504) is more than four times the diameter of the fifth opening (502).

9. A fuel connection block (300) according to claim 6 or 7, characterized in that cross-sectional area of the second and fourth openings is 0,2 - 0,5 times cross sectional area of the first and third openings (514,526).

10. A fuel connection block (300) according to claim 5, characterized in that the first channel system (538) comprises a primary flow connection (538.1) between the first opening (514) and the third opening (526), and that the fifth opening (502) is connect to the primary flow connection (538.1) via a secondary flow connection (538.2), wherein cross-sectional area of the primary flow connection (538.1) is at least 5 times greater than the cross-sectional area of the secondary flow connection (538.2).

11. A fuel connection block (300) according to claim 6 or 10, characterized in that mean cross-sectional area of the first channel system (538) is 2 to 5 times larger than mean cross-sectional area of the second channel system (550).3712. A fuel connection block (300) according to claim anyone of the preceding claims 6 to 11 , characterized in that fuel connection block (300) is provided with a closing valve (320) in the second channel system (550), which comprises - an inlet (324), which inlet of the closing valve is solely in flow connection with the sixth opening (504) in the third interface (306), and- an outlet (326), which outlet of the closing valve is in flow connection with both the second opening (516) in the first interface and the fourth opening (528) in the second interface,- a closing element (322), such as a piston, which is arranged axially movably between a first position at which the closing element closes flow connection between the inlet (324) and the outlet (326), and a second position at which the closing element (322) opens flow connection between the inlet and the outlet, wherein the closing element (322) is configured to open when pressure in the inlet (324) is greater than a threshold pressure which needs to be exceeded before the closing element changes its position from the first position to the second position.

13. A fuel connection block (300) according to claim 12, characterized in that the closing element (322) is a piston assembly, one end of which extending out from the fuel connection block (300) for visual indication of position of the closing element (322).

14. A method of retrofitting a used cylinder head (102) of an internal combustion piston engine, which used cylinder head (102) comprisesa. a fuel injector cavity (124) which extends through the cylinder head (102) perpendicularly to a fire face of the cylinder head (102), in which fuel injector cavity a twin-needle liquid fuel injector (106) is assembled, b. a start valve cavity (125) which extends through the cylinder head (102), and which is parallel to the fuel injector cavity, in which start valve cavity (125) an air start valve is assembled extending to the fire face of the cylinder head (102), and retained by a start valve extension part (228) in the start valve cavity (125),c. a first transverse space (122) extending from a side wall of the cylinder head (102) to the fuel injector cavity, through which a first liquid fuel quill38pipe (118) is led from side of the cylinder head (102) into contact with a fuel injector in the fuel injector cavity,d. a second transverse space (120) extending from the side wall of the cylinder head (102) to the fuel injector cavity, through which a second liquid fuel quill pipe (116) is led from side of the cylinder head (102) into contact with the fuel injector in the fuel injector cavity,wherein the method comprises• disassembling the first fuel quill pipe (118) from the first transverse space • disassembling the second fuel quill pipe (116) from the second transverse space• disassembling the twin-needle liquid fuel injector (106) from the fuel injector cavity• disassembling at least the start valve extension part (228) from the start valve cavity (125)and• assembling a new fuel ignitor (10) into the fuel injector cavity,• assembling a start valve extension part (228) according to anyone of the preceding claims 1 to 10 into the start valve cavity (125) in sealed manner, such thato the first transverse space forms a leakage channel (120) extending from the new fuel ignitor (10), via the start valve extension part (228), to open at a side wall of the cylinder head (102) and o the second transverse space forms a fuel feeding channel (120) extending from the new fuel ignitor (10), via the start valve extension part (228), to open at a side wall of the cylinder head (102), • assembling a fuel connection block (300) according to anyone of the claims 6 - 13 by attaching it to the cylinder head (102) so as to connect the fuel feeding channel (122) with fuel supply (604), and to connect the leakage channel (120) to leakage handling system (606).

15. An internal combustion piston engine, comprising a fuel delivery and leakage handling system according to anyone of the preceding claims 1 to 5.

Images