Cylinder cover, cylinder cover assembly and piston engine

Abstract

The cylinder head (1) includes an intake passage (3), an exhaust passage (4), intake valve holes (5A, 5B), exhaust valve holes (6A, 6B), a coolant chamber (16), and an integral extension (13) formed at an exhaust side (12) of the cylinder head (1), the extension (13) including a first push rod passage (14A) and a second push rod passage (14B), each of the first push rod passage (14A) and the second push rod passage (14B) being configured to allow a push rod (15) to pass therethrough, the push rod (15) is configured to operate an intake valve (8) and / or an exhaust valve (9) of the cylinder (2), and the exhaust passage (4) is arranged to pass between a first push rod passage (14A) and a second push rod passage (14B) in an extension (13).

Description

Technical Field

[0001] The invention relates to a cross-flow cylinder head for a single cylinder of a multi-cylinder piston engine as defined in claim 1. The invention also relates to a cylinder head assembly for a piston engine and to a piston engine. Background Art

[0002] In large piston engines, for example in engines used as main engines or auxiliary engines in ships, or in engines used in power plants for generating electricity, each cylinder of the engine is provided with its own cylinder head. The cylinder head closes the upper end of the cylinder and defines the main combustion chamber. In a four-stroke engine, the cylinder head serves several purposes. For example, the cylinder head is provided with intake ducts for introducing intake air into the combustion chamber and exhaust ducts for removing exhaust gases from the combustion chamber.

[0003] Since the cylinder head is in direct contact with the combustion chamber and hot exhaust gas flows through the cylinder head, cylinder head cooling is required to control the temperature of the cylinder head. Excessive temperature may damage the cylinder head and components attached to the cylinder head. However, excessive cooling is also harmful because it reduces the efficiency of the engine. In particular, the temperature of the exhaust gas should be high to ensure the efficient operation of the turbocharger. Summary of the invention

[0004] The object of the present invention is to provide an improved cross-flow cylinder head for a single cylinder of a multi-cylinder four-stroke piston engine. The characteristics of the cylinder head according to the invention are set out in claim 1. Another object of the present invention is to provide an improved cylinder head assembly. Yet another object of the present invention is to provide an improved piston engine.

[0005] The cylinder head according to the present invention has a bottom surface configured to face the cylinder of the engine and a top surface facing the opposite direction, and has an intake side and an exhaust side. The cylinder head includes:

[0006] - an air intake duct arranged on the air intake side;

[0007] - an exhaust duct arranged on the exhaust side;

[0008] - a first intake valve aperture and a second intake valve aperture disposed on the intake side, each intake valve aperture extending from the bottom surface to the top surface and configured to receive an intake valve;

[0009] - a first exhaust valve hole and a second exhaust valve hole arranged on the exhaust side, each exhaust valve hole extending from the bottom surface to the top surface and configured to receive an exhaust valve; and

[0010] -Coolant chamber.

[0011] The cylinder head also includes an integral extension portion formed on the exhaust side, the extension portion including a first push rod channel and a second push rod channel, each of the first push rod channel and the second push rod channel being configured to allow a push rod to pass therethrough, the push rod being configured to operate an intake valve and / or an exhaust valve of the cylinder, and the exhaust passage being arranged to pass through the extension portion between the first push rod channel and the second push rod channel.

[0012] The integrated extension on the exhaust side increases the efficiency, reliability and safety of the engine. The extension and in particular the push rod channel arranged on the side of the exhaust duct reduces the heat radiation from the exhaust duct. This helps both to keep the exhaust temperature high (which allows effective energy recovery in the turbocharger) and to reduce the surface temperature of the engine, thereby increasing the safety of the engine. The push rod channel also allows to collect the oil leakage from the valve actuator and prevents the oil from contacting the exhaust pipe components.

[0013] According to an embodiment of the invention, the cooling liquid chamber is arranged at least partially in an extension of the cylinder head. This reduces further heat radiation from the exhaust duct.

[0014] According to an embodiment of the present invention, the cylinder head includes at least one coolant outlet, which is arranged in the extension of the cylinder head for discharging coolant from the coolant cavity. The coolant conducted from the cylinder head through the extension provides an improved thermal barrier in the cylinder head and allows the coolant to be introduced into external components to block heat from the exhaust system.

[0015] According to an embodiment of the invention, the cylinder head comprises at least one coolant outlet arranged in the extension below the exhaust duct. This allows coolant to be discharged from the cylinder head below the exhaust duct and forms a heat barrier below the exhaust manifold.

[0016] According to an embodiment of the invention, the cylinder head comprises at least one coolant outlet arranged in the extension above the exhaust channel. This allows coolant to be discharged from the cylinder head above the exhaust channel and to form a heat barrier above or to the side of the exhaust manifold.

[0017] According to an embodiment of the invention, the cylinder head comprises at least two coolant outlets arranged in the extension above the exhaust duct. This allows a larger portion of the coolant to circulate above the exhaust pipe, where the temperature is high.

[0018] According to an embodiment of the present invention, the cooling liquid chamber includes a lower portion arranged on the bottom surface side of the exhaust passage and an upper portion arranged on the top surface side of the exhaust passage. This ensures effective cooling of the cylinder head around the exhaust pipe and forms a heat barrier around the exhaust pipe.

[0019] According to an embodiment of the present invention, the cylinder head includes a coolant pipe for introducing coolant into the coolant chamber.

[0020] According to an embodiment of the invention, the cooling liquid conduit comprises a first branch for introducing cooling liquid into the lower part of the cooling liquid cavity and a second branch for introducing cooling liquid into the upper part of the cooling liquid cavity. This ensures effective cooling in both parts of the cooling liquid cavity.

[0021] According to an embodiment of the present invention, the coolant conduit has an inlet end that leads to the bottom surface of the cylinder head. Therefore, the coolant can be led from the cylinder liner or the engine block to the cylinder head.

[0022] According to an embodiment of the present invention, the inlet end of the coolant duct is arranged to open in a region for receiving coolant from the coolant passage of the cylinder liner, the region being configured to align with the upper end of the cylinder liner in the mounted state of the cylinder head. This allows coolant to be supplied directly from the cylinder liner to the cylinder head.

[0023] According to an embodiment of the invention, the extension of the cylinder head is configured for attachment of a coolant module, which is configured to receive coolant from the coolant cavity. Thus, the coolant module can be arranged on the side of the cylinder head. This is advantageous, in particular in V-type engines, where the coolant module can be used as a heat shield below the exhaust manifold.

[0024] According to an embodiment of the present invention, the exhaust passage includes a first branch from a first exhaust valve hole and a second branch from a second exhaust valve hole, the first branch and the second branch merge into a common portion extending through the cylinder head.

[0025] According to an embodiment of the present invention, the exhaust passage in the extension of the cylinder head is configured to receive the inner sleeve. The inner sleeve can be used as a heat barrier to prevent heat conduction and radiation from the exhaust passage.

[0026] According to an embodiment of the present invention, the exhaust passage in the extension portion includes an outer support portion configured to support the outer end of the inner sleeve, an inner support portion configured to support the inner end of the inner sleeve, and an intermediate portion having a larger diameter than the inner support portion, so that a free space is formed between the exhaust passage and the inner sleeve in the installed state of the inner sleeve. The gap formed around the inner sleeve isolates the exhaust passage from the rest of the cylinder head and helps to keep the exhaust temperature high.

[0027] According to an embodiment of the present invention, the cylinder head includes a center hole that is disposed between the intake valve hole and the exhaust valve hole and extends from a bottom surface to a top surface.

[0028] According to an embodiment of the present invention, the central bore is configured to receive a fuel injector or a pre-combustion chamber assembly.

[0029] The cylinder head assembly according to the present invention comprises the cylinder head defined above and a coolant module attached to an extension of the cylinder head. The coolant module forms a heat shield at least on one side of the exhaust manifold.

[0030] A piston engine according to the invention comprises a cylinder head as defined above. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings, in which:

[0032] Figure 1 A perspective view of a cylinder head according to an embodiment of the present invention is shown;

[0033] Figure 2 The diagram shows the cylinder head as viewed from the extension direction. Figure 1 Cylinder head;

[0034] Figure 3 Shows Figure 1 A cross-sectional view of an extended portion of a cylinder head;

[0035] Figure 4 Shows Figure 1 A sectional view of a lower portion of a cylinder head;

[0036] Figure 5 Shows Figure 1 a cross-sectional view of a cylinder head and components attached to the cylinder head;

[0037] Figure 6 Shows Figure 1 a cross-sectional view of a portion of a cylinder head and components attached to the cylinder head; and

[0038] Figure 7 Shows Figure 1 Another cross-sectional view of a portion of a cylinder head and components attached to the cylinder head. DETAILED DESCRIPTION

[0039] Figure 1 A cylinder head 1 according to an embodiment of the present invention is shown. The cylinder head 1 is a cylinder head of a large piston engine. The expression "large piston engine" here refers to an engine with a cylinder diameter of at least 150 mm. The engine can be, for example, an engine used as a main engine or an auxiliary engine in a ship, or an engine used in a power plant to drive a generator to generate electricity. The engine is a multi-cylinder four-stroke engine. The number of cylinders in the engine can be, for example, 5 to 20. The cylinders can be arranged in line or in a V-type.

[0040] The cylinder head 1 is configured to close the upper ends of the cylinders 2 of the engine. Each cylinder 2 of the engine is provided with its own cylinder head 1. The cylinder head 1 is a one-piece part.

[0041] An engine in which the cylinder head 1 is used can be configured to operate using at least a first gaseous fuel. The expression "gaseous fuel" refers here to a fuel that is gaseous at atmospheric pressure and a temperature of 20° C. The first fuel can be, for example, natural gas or biogas. The term "biogas" refers here to a gas that consists mainly of methane and is obtained from a renewable source. Biogas can, for example, be produced from organic waste. Natural gas can be stored as liquefied gas (LNG) or compressed gas (CNG). Biogas can be stored in a similar manner. Instead of a methane-based fuel, the first fuel can be, for example, hydrogen or ammonia or a mixture of two or more types of gaseous fuels.

[0042] The engine can also be configured to operate using a second fuel. The second fuel can be either a gaseous fuel or a liquid fuel. If the first fuel is natural gas or biogas, the second fuel can be, for example, hydrogen. Alternatively, the second fuel can be a liquid fuel, such as light fuel oil or heavy fuel oil. The engine can also operate using a third fuel or even more fuels.

[0043] Thus, the engine may be a gas engine, a dual fuel engine or a multi-fuel engine. However, the engine may also be operable using only one or more liquid fuels.

[0044] The engine can be configured to operate with a mixture of different fuels. For example, the engine can operate with a mixture of hydrogen and some other gaseous fuel and / or a mixture of ammonia and some other gaseous fuel.

[0045] When the engine is operated using gaseous fuel, it can use liquid fuel (such as light fuel oil) as a pilot fuel to promote the ignition of the gaseous fuel. However, this is not required, but the gaseous fuel can be self-igniting, or a spark plug or other ignition device can be used to ignite the gaseous fuel.

[0046] The cylinder head 1 has a bottom surface 1A and a top surface 1B, the bottom surface 1A being configured to define the upper end of the main combustion chamber 31 of the cylinder 2, and the top surface 1B facing in a direction opposite to the bottom surface 1A. The cylinder 2 of the engine need not be in an upright position, but the cylinder 2 may be tilted from a vertical direction. For example, in a V-type engine, the upper end of the cylinder 2 may be further away from the longitudinal centerline of the engine than the lower end. Therefore, the term "bottom surface" refers to the side of the cylinder head 1 that faces the main combustion chamber 31, but the bottom surface 1A need not be a horizontal surface facing downward.

[0047] The engine includes an engine block and a cylinder liner 19 arranged in the engine block. The cylinder 2 is formed by the cylinder liner 19. The upper end of each cylinder liner 19 extends above the upper surface of the engine block. The cylinder head 1 can be arranged against the upper end of the cylinder liner 19 and attached to the engine block.

[0048] The cylinder head 1 is a cross-flow cylinder head. The term “cross-flow cylinder head” means that the intake valve and the exhaust valve are located on opposite sides of the cylinder head 1.

[0049] The cylinder head 1 has an intake side 11 and an exhaust side 12. When the cylinder head 1 is divided into two halves by an imaginary plane 32 (which is parallel to the axial direction of the cylinder 2 in the installed state of the cylinder head 1), the intake side 11 is the side of the cylinder head 1 where the intake valve 8 of the cylinder 2 is located, and the exhaust side 12 is the side of the cylinder head 1 where the exhaust valve 9 of the cylinder 2 is located. The imaginary plane 32 does not have to be in the middle of the cylinder head 1. In the embodiment of the accompanying drawings, the imaginary plane 32 that divides the cylinder head 1 into the intake side 11 and the exhaust side 12 is positioned so that in the installed state of the cylinder head 1, the imaginary plane 32 intersects the longitudinal center axis of the cylinder 2. In the installed state of the cylinder head 1, the intake side 11 of the cylinder head 1 is located on a first side of the longitudinal center line of a row of cylinders. The exhaust side 12 of the cylinder head 1 is located on a second side of the longitudinal center line of the row of cylinders. In an in-line engine, the intake side 11 of all cylinder heads 1 of the engine is located on the same side of the longitudinal centerline of the cylinders. In a V-type engine, the cylinder heads 1 may be mounted so that the exhaust side 12 of the cylinder heads 1 of the first row faces the exhaust side 12 of the cylinder heads 1 of the second row. Thus, the intake side 11 of the cylinder heads 1 may point laterally outward from the longitudinal centerline of the engine.

[0050] The imaginary plane 32 does not necessarily intersect with the longitudinal center axis of the cylinder 2 , but the imaginary plane 32 may be offset from the longitudinal center axis of the cylinder 2 .

[0051] The cylinder head 1 includes attachment holes 34 for attaching the cylinder head 1 to the engine block. In the embodiment of the drawings, the cylinder head 1 includes four attachment holes 34. Each attachment hole 34 is configured to receive a stud bolt for attaching the cylinder head 1 to the engine block. In the installed state of the cylinder head 1, the radial distances of the attachment holes 34 from the longitudinal center axis of the cylinder 2 are equal to each other.

[0052] The cylinder head 1 includes an intake port 3 arranged on the intake side 11 of the cylinder head 1. The intake port 3 is configured to introduce intake air into the main combustion chamber 31 of the cylinder 2. In the embodiment of the drawings, the intake port 3 is also configured to allow gaseous main fuel to be introduced into the intake port 3 and further into the main combustion chamber 31. The cylinder head 1 also includes an exhaust port 4 arranged on the exhaust side 12 of the cylinder head 1. The exhaust port 4 is configured to discharge exhaust gas from the main combustion chamber 31.

[0053] The cylinder head 1 includes a first intake valve hole 5A and a second intake valve hole 5B arranged on the intake side 11 of the cylinder head 1. Each intake valve hole 5A, 5B extends from a bottom surface 1A to a top surface 1B of the cylinder head 1 and is configured to receive an intake valve 8. Therefore, the cylinder head 1 may be provided with two intake valves 8.

[0054] The cylinder head 1 comprises a first exhaust valve hole 6A and a second exhaust valve hole 6B arranged at the exhaust side 12 of the cylinder. Each exhaust valve hole 6A, 6B extends from the bottom surface 1A to the top surface 1B and is configured to receive an exhaust valve 9. Thus, the cylinder head 1 may be provided with two exhaust valves 9.

[0055] In the embodiment of the drawings, the cylinder head 1 further includes a central hole 29, which is arranged between the intake valve holes 5A, 5B and the exhaust valve holes 6A, 6B and extends from the bottom surface 1A to the top surface 1B of the cylinder head 1. In the embodiment of the drawings, the central hole 29 is configured to receive a fuel injector 30. The fuel injector 30 is configured to inject liquid pilot fuel into the main combustion chamber 31. However, the central hole 29 may also be configured to receive a pre-combustion chamber assembly.

[0056] The cylinder head 1 further comprises an integral extension 13 formed on the exhaust side 12. In the embodiment of the figures, the cylinder head 1 extends further on the exhaust side 12 than on the intake side 11 from the area covering the cylinders 2 in the mounted state of the cylinder head 1.

[0057] The extension 13 includes a first push rod passage 14A and a second push rod passage 14B. Each of the push rod passages 14A, 14B is configured to allow a push rod 15 to pass therethrough. Therefore, the push rod 15 can be inserted through the push rod passages 14A, 14B. In the installed state of the cylinder head 1, the push rod 15 can be operated by means of a camshaft, which is located below the level of the bottom surface 1A of the cylinder head 1. The push rod 15 can operate a valve actuation mechanism, which is at least partially located above the level of the top surface 1B of the cylinder head 1. In the installed state of the cylinder head 1, the push rod passages 14A, 14B are positioned farther from the longitudinal center axis of the cylinder 2 than the attachment hole 34.

[0058] One of the push rods 15 is configured to operate the intake valve 8 of the cylinder 2, and one of the push rods 15 is configured to operate the exhaust valve 9 of the cylinder 2. The push rods 15 are lifted by the cams of the camshaft. If the cylinder head 1 is used in a V-type engine, the cams for the two banks of cylinders 2 of the engine can be arranged in the same camshaft. The push rods are biased against the cams by springs. The push rod channels 14A, 14B collect lubricating oil from the valve actuation mechanism above the cylinder head 1 and guide the lubricating oil through the exhaust passage 4.

[0059] The exhaust passage 4 is arranged to pass through the extension 13 between the first push rod passage 14A and the second push rod passage 14B. The exhaust passage 4 opens to the side of the cylinder head 1 in the extension 13. The extension 13 is configured to allow the exhaust manifold 43 to be attached to the extension 13 and to be in fluid communication with the exhaust passage 4. Therefore, the push rod passages 14A, 14B are arranged on both sides of the exhaust passage 4, thereby forming a heat barrier on both sides of the exhaust passage 4. This reduces heat radiation and conduction from the exhaust passage 4 to the outside of the cylinder head 1. The extension 13 is provided with a threaded hole 35 for allowing the exhaust manifold 43 to be attached to the extension 13 by screws 36.

[0060] Can be Figures 5 to 7 4. The exhaust manifold 43 is seen in FIG. The exhaust manifold 43 comprises a longitudinal portion 45. The axial direction of the longitudinal portion 45 is parallel to the longitudinal direction of the row of cylinders. The exhaust manifold 43 also comprises a plurality of branches 46 connecting the longitudinal portion 45 to the exhaust ducts 4 of the cylinder head 1. The number of branches 46 in the exhaust manifold 43 is equal to the number of cylinders 2 to which the exhaust manifold 43 is connected. An in-line engine may comprise a single exhaust manifold. A V-type engine may be provided with a separate exhaust manifold for each cylinder bank. Each branch 46 of the exhaust manifold comprises a mounting flange 53 for attaching the branch 46 to the extension 13 of the cylinder head 1.

[0061] The exhaust passage 4 includes a first branch 4A from the first exhaust valve hole 6A and a second branch 4B from the second exhaust valve hole 6B. The first branch 4 and the second branch 4B merge into a common portion 4C, which passes through the extension 13 of the cylinder head 1. The exhaust passage 4 merges into the common portion 4C before the push rod passages 14A, 14B.

[0062] The cylinder head 1 includes a coolant cavity 16. The coolant cavity 16 is configured to receive and discharge coolant to allow the coolant to circulate in the cylinder head 1. In the embodiment of the drawings, the coolant is received from a coolant duct 20 of a cylinder liner 19 and discharged from an extension 13 of the cylinder head 1. In the embodiment of the drawings, the coolant cavity 16 is partially arranged in the extension 13.

[0063] The cooling liquid chamber 16 includes a lower portion 16A and an upper portion 16B. The lower portion 16A is arranged below the exhaust passage 4, that is, on the bottom surface side of the exhaust passage 4. The upper portion 16B is arranged above the exhaust passage 4, that is, on the top surface side of the exhaust passage 4. In the embodiment of the drawings, the upper portion 16B is connected to the lower portion 16A at the side of the exhaust passage 4.

[0064] The cylinder head 1 includes a coolant conduit 17 for introducing coolant into the coolant chamber 16. In the embodiment of the drawings, the coolant conduit 17 includes a first branch 17A for introducing coolant into the lower portion 16A of the coolant chamber 16 and a second branch 17B for introducing coolant into the upper portion 16B of the coolant chamber 16. The coolant conduit 17 has an inlet end 18 leading to the bottom surface 1A of the cylinder head 1. The inlet end 18 of the coolant conduit 17 is arranged to open in a region for receiving coolant from a coolant passage 20 of a cylinder liner 19, the region being configured to be aligned with the upper end of the cylinder liner 19 in the mounted state of the cylinder head 1.

[0065] The second branch 17B of the coolant duct 17 comprises a portion extending in the direction of the central hole 29 of the cylinder head 1. The portion is arranged between the central hole 29 and the exhaust passage 4 so that it is located closer to the central hole 29 than the exhaust passage 4. This helps to avoid excessive cooling of the exhaust gases.

[0066] The cylinder head 1 comprises at least one coolant outlet 21, 22A, 22B arranged in the extension 13 of the cylinder head 1 for discharging coolant from the coolant cavity 16. In the embodiment of the accompanying drawings, the cylinder head 1 comprises three coolant outlets 21, 22A, 22B. The first coolant outlet 21 is arranged below the exhaust passage 4. The first coolant outlet 21 is configured to discharge coolant from the lower portion 16A of the coolant cavity 16. The cylinder head 1 also comprises a second coolant outlet 22A and a third coolant outlet 22B. The second coolant outlet 22A and the third coolant outlet 22B are configured to discharge coolant from the upper portion 16B of the coolant cavity 16.

[0067] The extension 13 of the cylinder head 1 is configured for attachment of a coolant module 23, which is configured to receive coolant from the coolant cavity 16. The coolant module 23 is arranged to receive coolant via the coolant outlets 21, 22A, 22B of the cylinder head 1. The coolant module 4323 forms a thermal barrier below the exhaust manifold 43. The coolant module 23 includes a lower portion 23A and an upper portion 23D. The lower portion 23A of the coolant module 23 is arranged to receive coolant via the first coolant outlet 21 of the cylinder head 1, and the upper portion 23D is arranged to receive coolant via the second coolant outlet 22A and the third coolant outlet 22B of the cylinder head 1. The lower portion 23A and the upper portion 23D of the coolant module 23 are arranged to be in fluid communication with each other via the side of the coolant module 23.

[0068] In the embodiment of the drawings, the lower portion 23A of the coolant module 23 includes a coolant inlet 50 arranged to receive coolant from the coolant cavity 16 of the cylinder head 1. The lower portion 23A of the coolant module 23 can be connected to the lower portion 16A of the coolant cavity 16 of the cylinder head 1. The upper portion 23D of the coolant module 23 includes two coolant inlets 51 arranged to receive coolant from the cylinder head 1. The upper portion 23D of the coolant module 23 can be connected to the upper portion 16B of the coolant cavity 16 of the cylinder head 1.

[0069] The lower portion 23A of the coolant module 23 has an end face 54 located away from the cylinder head 1. The mutual angle between the end face 54 and the axial direction of the corresponding cylinder 1 is preferably 15 to 40 degrees, and the upper edge of the end face 54 is farther away from the cylinder 2 than the lower edge. This allows the same coolant module 23 to be used in a V-type engine and an in-line engine. The angle is preferably substantially equal to the inclination angle of the cylinder 2 of the V-type engine relative to the vertical direction. In an in-line engine, the end face 54 can be used as an attachment point for a heat shield surrounding the exhaust manifold 43.

[0070] The exhaust passage 4 in the extension 13 of the cylinder head 1 is configured to receive the inner sleeve 24. In the embodiment of the drawings, the exhaust passage 4 in the extension 13 includes an outer support portion 25 and an inner support portion 26, the outer support portion 25 being configured to support the outer end of the inner sleeve 24, and the inner support portion 26 being configured to support the inner end of the inner sleeve 24. The exhaust passage 4 also includes an intermediate portion 27, which has a larger diameter than the inner support portion 26, so that in the installed state of the inner sleeve 24, a free space 28 is formed between the exhaust passage 4 and the inner sleeve 24. In the embodiment of the drawings, the outer diameter of the inner sleeve 24 is constant. The inner diameter of the inner support portion 26 is substantially the same as the inner diameter of the outer support portion 25. However, the inner diameter of the outer support portion 25 may be larger than the inner diameter of the inner support portion 26. In this case, the diameter of the inner sleeve 24 may increase toward the outer end, or an intermediate piece may be arranged between the inner sleeve 24 and the outer support portion 25. Exhaust gas flows in the inner sleeve 24. The inner sleeve and the free space 28 surrounding the inner sleeve 24 reduce heat radiation and conduction from the exhaust passage 4 .

[0071] It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may be varied within the scope of the appended claims.

Claims

1. A cross-flow cylinder head (1) for a single cylinder (2) of a multi-cylinder four-stroke piston engine, the cylinder head (1) having a bottom surface (1A) and a top surface (1B), the bottom surface (1A) being configured to face the cylinder (2) of the engine, the top surface (1B) facing in the opposite direction, the cylinder head (1) also having an intake side (11) and an exhaust side (12), the cylinder head (1) comprising: - an air intake duct (3) arranged on the air intake side (11); - an exhaust duct (4) arranged on the exhaust side (12); - a first intake valve hole (5A) and a second intake valve hole (5B) arranged on the intake side (11), each intake valve hole (5A, 5B) extending from the bottom surface (1A) to the top surface (1B) and configured to receive an intake valve (8); - a first exhaust valve hole (6A) and a second exhaust valve hole (6B) arranged on the exhaust side (12), each exhaust valve hole (6A, 6B) extending from the bottom surface (1A) to the top surface (1B) and configured to receive an exhaust valve (9); as well as - a cooling liquid chamber (16), Wherein, the cylinder head (1) also includes an integral extension portion (13) formed on the exhaust side (12), the extension portion (13) including a first push rod channel (14A) and a second push rod channel (14B), each of the first push rod channel (14A) and the second push rod channel (14B) being configured to allow a push rod (15) to pass therethrough, the push rod (15) being configured to operate an intake valve (8) and / or an exhaust valve (9) of the cylinder (2), and wherein the exhaust passage (4) is arranged to pass through the extension portion (13) between the first push rod channel (14A) and the second push rod channel (14B).

2. The cross-flow cylinder head (1) according to claim 1, wherein: The cooling liquid chamber (16) is at least partially arranged in the extension (13) of the cylinder head (1).

3. The cross-flow cylinder head (1) according to claim 1 or 2, wherein: The cylinder head (1) comprises at least one coolant outlet (21, 22A, 22B), wherein the at least one coolant outlet (21, 22A, 22B) is arranged in an extension portion (13) of the cylinder head (1) and is used to discharge coolant from the coolant cavity (16).

4. The cross-flow cylinder head (1) according to claim 3, wherein: The cylinder head (1) comprises at least one coolant outlet (21) arranged in the extension (13) below the exhaust passage (4).

5. The cross-flow cylinder head (1) according to claim 3 or 4, wherein: The cylinder head (1) comprises at least one coolant outlet (22A, 22B) arranged in the extension (13) above the exhaust passage (4).

6. The cross-flow cylinder head (1) according to claim 5, wherein: The cylinder head (1) comprises at least two coolant outlets (22A, 22B) arranged in the extension (13) above the exhaust passage (4).

7. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The cooling liquid chamber (16) includes a lower portion (16A) arranged on the bottom surface side of the exhaust passage (4) and an upper portion (16B) arranged on the top surface side of the exhaust passage (4).

8. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The cylinder head (1) comprises a coolant pipe (17) for introducing coolant into the coolant chamber (16).

9. Cross-flow cylinder head (1) according to claims 7 and 8, wherein: The cooling liquid conduit (17) includes a first branch (17A) for introducing cooling liquid into a lower portion (16A) of the cooling liquid chamber (16) and a second branch (17B) for introducing cooling liquid into an upper portion (16B) of the cooling liquid chamber (16).

10. The cross-flow cylinder head (1) according to claim 8 or 9, wherein: The coolant conduit (17) has an inlet end (18) that opens to the bottom surface (1A) of the cylinder head (1).

11. The cross-flow cylinder head (1) according to claim 10, wherein: The inlet end (18) of the coolant duct (17) is arranged to open in a region for receiving coolant from a coolant passage (20) of the cylinder liner (19), the region being configured to align with an upper end of the cylinder liner (19) when the cylinder head (1) is installed.

12. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The extension (13) of the cylinder head (1) is configured for attachment of a coolant module (23), the coolant module (23) being configured to receive coolant from the coolant cavity (16).

13. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The exhaust passage (4) includes a first branch (4A) from the first exhaust valve hole (6A) and a second branch (4B) from the second exhaust valve hole (6B), wherein the first branch (4A) and the second branch (4B) merge into a common portion (4C) passing through an extension portion (13) of the cylinder head (1).

14. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The exhaust passage (4) in the extension (13) of the cylinder head (1) is configured to receive an inner sleeve (24).

15. The cross-flow cylinder head (1) according to claim 14, wherein: The exhaust passage (4) in the extension portion (13) comprises an outer supporting portion (25), an inner supporting portion (26) and an intermediate portion (27), wherein the outer supporting portion (25) is configured to support the outer end of the inner sleeve (24), the inner supporting portion (26) is configured to support the inner end of the inner sleeve (24), and the intermediate portion (27) has a larger diameter than the inner supporting portion (26), so that a free space (28) is formed between the exhaust passage (4) and the inner sleeve (24) when the inner sleeve (24) is installed.

16. A cross-flow cylinder head (1) according to any one of the preceding claims, wherein: The cylinder head (1) includes a center hole (29) which is arranged between the intake valve holes (5A, 5B) and the exhaust valve holes (6A, 6B) and extends from the bottom surface (1A) to the top surface (1B).

17. The cross-flow cylinder head (1) according to claim 16, wherein: The central bore (29) is configured to receive a fuel injector (30) or a pre-combustion chamber assembly.

18. A cylinder head assembly comprising a cylinder head (1) according to any one of the preceding claims and a coolant module (23) attached to an extension (13) of the cylinder head (1).

19. A piston engine comprising a cylinder head (1) according to any one of claims 1 to 17.

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