Piston engine

Abstract

The piston engine comprises: cylinders (2) arranged in at least one row (41, 42); at least one exhaust manifold (43, 44) having a longitudinal portion (45) and a branch (46) connecting the longitudinal portion (45) to the exhaust passage (4) of the cylinder head (1); and a coolant module (23) attached to the cylinder head (1) and arranged to receive coolant from a coolant cavity (16) of the cylinder head (1), the coolant module (23) comprising a lower portion (23A) protruding from the cylinder head (1) in a direction perpendicular to a longitudinal direction of the at least one row (41, 42) of cylinders below a branch (46) of the exhaust manifold (43, 44), the projection of said lower portion (23A) on the horizontal plane extends from the cylinder head (1) in a direction perpendicular to the longitudinal direction of the at least one row (41, 42) of cylinders to at least the same distance as the projection of the branches (46) of the exhaust manifolds (43, 44).

Description

Technical Field

[0001] The invention relates to a piston engine as defined in claim 1. Background Art

[0002] In large piston engines, for example in engines used as main engines or auxiliary engines in ships or 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 discharging exhaust gases from the combustion chamber.

[0003] The exhaust gases exiting the cylinders of an engine have a high temperature. Hot surfaces of the exhaust system may lead to safety risks, so it is necessary to protect the hot parts of the exhaust system, for example by means of different insulation solutions. Different insulation solutions are often bulky and may limit the possibilities for positioning the various components of the engine. Summary of the invention

[0004] The object of the invention is to provide an improved piston engine comprising a plurality of cylinders arranged in at least one bank of cylinders.The characteristics of the piston engine according to the invention are set out in claim 1 .

[0005] The piston engine according to the present invention comprises a plurality of cylinders arranged in at least one row of cylinders, each cylinder being provided with a cylinder head, the cylinder head comprising an exhaust passage for exhausting exhaust gases from the cylinder and comprising a coolant cavity through which a coolant can circulate, the engine comprising at least one exhaust manifold having a longitudinal portion extending in the longitudinal direction of the row of cylinders and a branch connecting the longitudinal portion to the exhaust passage of the cylinder head, wherein the engine comprises at least one coolant module, the coolant module being attached to the cylinder head of the engine and being arranged to receive coolant from the coolant cavity of the cylinder head, the coolant module comprising at least a lower portion, the lower portion being arranged to protrude from the cylinder head in a direction perpendicular to the longitudinal direction of the at least one row of cylinders below a corresponding branch of the exhaust manifold, and wherein a projection of the lower portion of the coolant module on a horizontal plane extends from the cylinder head in a direction perpendicular to the longitudinal direction of the at least one row of cylinders to at least the same distance as a projection of the branch of the exhaust manifold on the plane.

[0006] The lower part of the coolant cavity forms a heat barrier below the branches of the exhaust manifold, thereby reducing the heat radiation downward from the branches of the exhaust manifold. This reduces the heating of the engine components below the exhaust manifold and minimizes the risk of fire. It also simplifies the insulation of the exhaust manifold.

[0007] According to an embodiment of the invention, the engine is a V-type engine, the V-type engine comprising a first bank of cylinders, a second bank of cylinders and at least one exhaust manifold, the exhaust manifold being arranged between the first bank of cylinders and the second bank of cylinders in a lateral direction of the engine. The coolant module provides particular benefits in V-type engines, where thermal insulation between cylinder banks below the exhaust manifold is difficult to achieve. However, the invention also provides benefits in in-line engines.

[0008] According to an embodiment of the invention, the exhaust passages of the cylinder head of each bank of cylinders are arranged to open toward the other bank of cylinders, and the engine includes at least one coolant module attached to the cylinder head of the first bank of cylinders and at least one coolant module attached to the cylinder head of the second bank of cylinders. When the exhaust gas from the two cylinder groups is conducted in the exhaust manifold arranged between the cylinder groups, the thermal insulation of the exhaust manifold is challenging. The coolant modules provided for the two cylinder groups of the engine provide an effective thermal barrier between the cylinder groups.

[0009] According to an embodiment of the invention, the coolant modules of the first bank of cylinders and the second bank of cylinders are identical to each other. This simplifies assembly and maintenance of the engine and reduces the number of different components required for engines with different cylinder configurations.

[0010] According to an embodiment of the invention, the dimensions of the lower parts of the coolant modules of the first and second banks of cylinders are determined such that the gap between the lower parts of the coolant modules of the first bank of cylinders and the lower parts of the corresponding coolant modules of the second bank of cylinders is at most 20 mm. According to an embodiment of the invention, the gap is at most 10 mm, preferably at most 5 mm. The small gap between the coolant modules ensures an effective heat barrier effect.

[0011] According to an embodiment of the invention, the gap is at least 2 mm.While it is beneficial to keep the gap small, it is also advantageous to arrange the coolant modules at a distance from each other to allow for thermal expansion.

[0012] According to an embodiment of the invention, the engine comprises a heat shield extending above the exhaust manifold from a coolant module of a first bank of cylinders to a coolant module of a second bank of cylinders. The heat shield supplements the protection provided by the coolant module.

[0013] According to an embodiment of the present invention, an engine includes a first exhaust manifold for a first bank of cylinders and a second exhaust manifold for a second bank of cylinders.

[0014] According to an embodiment of the invention, the lower part of the coolant module protrudes from the cylinder head in such a direction that the distance between the corresponding branch of the exhaust manifold and the lower part of the coolant module increases towards the end of the module and the branch which is further away from the at least one bank of cylinders. The space in the cylinder head is limited and the coolant module needs to be attached close to the branch of the exhaust manifold. The increased distance between the branch and the coolant module ensures that unnecessary cooling of the exhaust gases is avoided.

[0015] According to an embodiment of the invention, the lower part of the coolant module comprises at least one coolant inlet arranged to receive coolant from the coolant cavity of the cylinder head.The direct coolant supply from the cylinder head ensures effective circulation of the coolant in the coolant module.

[0016] According to an embodiment of the present invention, the coolant module further comprises a first side portion extending upward from the lower portion at a first side of the branch of the exhaust manifold and a second side portion extending upward from the lower portion at a second side of the branch of the exhaust manifold. The side portion allows the coolant to be conducted to the upper side of the exhaust manifold.

[0017] According to an embodiment of the invention, the lower portion extends further from the cylinder head in a lateral direction of at least one bank of cylinders than the side portions. This allows providing an effective heat shield below the branches of the exhaust manifold while minimizing cooling of the exhaust gas.

[0018] According to an embodiment of the invention, the coolant module comprises an upper portion connecting the first side portion to the second side portion above a branch of the exhaust manifold. The upper portion allows collecting coolant from the side portions.

[0019] According to an embodiment of the invention, the lower portion extends further from the cylinder head in the lateral direction of at least one bank of cylinders than the upper portion. Like the side portions, this allows providing an effective heat barrier while minimizing cooling of the exhaust gas.

[0020] According to an embodiment of the invention, the upper part of the coolant module comprises at least one coolant inlet arranged to receive coolant from the cylinder head. This allows optimizing the coolant flow in the cylinder head.

[0021] According to an embodiment of the invention, the upper part of the coolant module comprises at least two coolant inlets arranged to receive coolant from the cylinder head. The two coolant inlets allow more coolant flow to be arranged in the upper part of the cylinder head.

[0022] According to an embodiment of the present invention, each cylinder of the engine is provided with its own coolant module. By providing each cylinder of the engine with its own coolant module, the same components can be used in engines with different numbers of cylinders. In addition, the maintainability of the engine is improved.

[0023] According to an embodiment of the invention, each cooling liquid module is arranged in fluid communication with at least one adjacent cooling liquid module.Thus, these cooling liquid modules may form part of a return line for the cooling liquid.

[0024] According to an embodiment of the present invention, each branch of the exhaust manifold is attached to the corresponding cylinder head through a mounting flange, and the coolant module is configured so that the projection of the coolant module on the plane of the mounting flange is located outside the mounting flange. Therefore, even when the coolant module is installed, the mounting flange can be accessed, thereby allowing the exhaust manifold to be installed and removed.

[0025] According to an embodiment of the present invention, the lower part of the coolant module has an end face positioned away from the corresponding cylinder head, and the mutual angle between the end face and the axial direction of the corresponding cylinder is 15 to 40 degrees, and the upper edge of the end face is farther away from the cylinder than the lower edge. The inclination of the end face allows the same module to be used in an in-line engine and for two groups of cylinders of a V-type engine. Because of the inclination, in a V-type engine, the end faces of the opposite coolant modules can be arranged close to each other.

[0026] According to an embodiment of the present invention, the engine is a V-type engine, and the angle is substantially equal to the inclination angle of the cylinder relative to the vertical direction. When the angle is equal to the inclination angle of the cylinder, the gap between the end surfaces has a constant width.

[0027] According to an embodiment of the present invention, the cylinder head includes an integral extension formed on the exhaust side of the cylinder head, the extension includes a first push rod channel and a second push rod channel, each of the first push rod channel and the second push rod channel is 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 is arranged to pass through the extension between the first push rod channel and the second push rod channel, and the coolant module is attached to the extension of the cylinder head. The extension reduces heat radiation downward from the exhaust passage, thereby providing a synergistic effect with the coolant module.

[0028] According to an embodiment of the invention, the exhaust manifold comprises a plurality of exhaust manifold modules, each module comprising a section of a longitudinal portion of the exhaust manifold and a branch of the exhaust manifold. Together with the coolant module, the exhaust manifold module helps to reduce the number of different components required for engines with different numbers of cylinders. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings, in which:

[0030] Figure 1 shows a portion of an engine according to an embodiment of the present invention;

[0031] Figure 2A cross-sectional view showing a portion of an engine according to an embodiment of the present invention;

[0032] Figure 3 Another cross-sectional view showing a portion of an engine according to an embodiment of the present invention;

[0033] Figure 4 A cross-sectional view of a V-type engine according to an embodiment of the present invention is shown;

[0034] Figure 5 shows another cross-sectional view of an engine according to an embodiment of the present invention;

[0035] Figure 6 shows another cross-sectional view of an engine according to an embodiment of the present invention;

[0036] Figure 7 shows another cross-sectional view of an engine according to an embodiment of the present invention;

[0037] Figure 8 shows a perspective view of a cylinder head which may form part of an engine according to an embodiment of the present invention;

[0038] Fig. 9 The cylinder head is shown as viewed from the direction of the extension Figure 8 Cylinder head;

[0039] Fig.10 Shows Figure 8 A cross-sectional view of an extended portion of a cylinder head; and

[0040] Fig.11 Shows Figure 8 A cross-sectional view of the lower portion of the cylinder head. DETAILED DESCRIPTION

[0041] Figures 1 to 11 Different partial views of a piston engine and components of the engine are shown according to different embodiments of the invention.

[0042] The engine according to the invention is 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 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 an in-line or V-shaped configuration. Figure 4 An example of a V-type engine is shown. Figure 2 An example of an in-line engine is shown.

[0043] The in-line engine comprises a single row 41 of cylinders 2. In an in-line engine, the cylinders 2 of the engine are preferably arranged in an upright position. Therefore, the longitudinal axis of each cylinder 2 is parallel to the vertical direction.

[0044] The V-type engine includes two rows of cylinders, i.e. two groups of cylinders. The cylinders 2 are arranged into a first row 41 of cylinders and a second row 42 of cylinders. The cylinders 2 in each row 41, 42 of cylinders 2 are inclined relative to the vertical direction, so that the distance between the two rows 41, 42 of cylinders 2 at the upper end of the cylinders 2 is greater than the distance at the lower end of the cylinders 2. Figure 4 In the embodiment of the invention, the inclination angle is about 20 degrees. Therefore, the angle between the axial direction of the cylinder 2 in the first row 41 of cylinders and the axial direction of the cylinder 2 in the second row 42 of cylinders is about 40 degrees. The inclination angle between the vertical direction and the axial direction of the cylinder 2 can be, for example, 15 to 40 degrees. The longitudinal direction of the second row 42 of cylinders is parallel to the longitudinal direction of the first row 41 of cylinders.

[0045] The engine includes an engine block 56 and a cylinder liner 19 arranged in the engine block 56. The cylinders 2 are formed by the cylinder liners 19. The upper end of each cylinder liner 19 extends beyond the upper surface of the engine block 56. Each cylinder 2 of the engine is provided with a cylinder head 1, which can be arranged against the upper end of the cylinder liner 19 and attached to the engine block 56.

[0046] The engine according to the invention can be configured to be able 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.

[0047] The engine may also be configured to operate using a second fuel. The second fuel may be either a gaseous fuel or a liquid fuel. If the first fuel is natural gas or biogas, the second fuel may be, for example, hydrogen. Alternatively, the second fuel may be a liquid fuel, such as light fuel oil or heavy fuel oil. The engine may also be capable of operating using a third fuel or even more fuels.

[0048] Therefore, the engine can be a gas engine, a dual fuel engine or a multi-fuel engine. However, the engine may also be capable of operating using only one or more liquid fuels.

[0049] The engine may be configured to be able to operate using a mixture of different fuels. For example, the engine may be able to operate using a mixture of hydrogen and some other gaseous fuel and / or a mixture of ammonia and some other gaseous fuel.

[0050] 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, and the gaseous fuel can be self-igniting, or a spark plug or other ignition device can be used to ignite the gaseous fuel.

[0051] Each cylinder 2 of the engine is provided with its own cylinder head 1. The cylinder head 1 is configured to close the upper end of the cylinder 2. The cylinder head 1 is preferably a one-piece component. The cylinder heads 1 of the engines are preferably identical to each other. In the embodiment of the figures, the cylinder head 1 of the V-type engine is identical to the cylinder head 1 of the in-line engine.

[0052] In particular, Figures 5 to 11 Details of a cylinder head 1 which can be used in an engine according to the invention are shown. However, the cylinder head 1 of an engine according to the invention can also differ from the cylinder head 1 described below.

[0053] 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. As described above, the cylinder 2 of the engine does not have to be in an upright position, but the cylinder 2 can be tilted from the vertical direction. For example, in a V-type engine, the upper end of the cylinder 2 can be further outward from the longitudinal centerline of the engine than the lower end. Therefore, the term "bottom surface" refers to the side of the cylinder head 1 facing the main combustion chamber 31, but the bottom surface 1A is not necessarily a horizontal surface facing downward.

[0054] 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.

[0055] 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 (the imaginary plane 32 is parallel to the axial direction of the cylinder 2 in the installed state of the cylinder head 1), the intake side 11 is a side of the cylinder head 1 on which the intake valve 8 of the cylinder 2 is located, and the exhaust side 12 is a side of the cylinder head 1 on which 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 are located on the same side of the longitudinal centerline of the bank of 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 group face the exhaust side 12 of the cylinder heads 1 of the second group. Thus, the intake side 11 of the cylinder heads 1 may point laterally outward from the longitudinal centerline of the engine.

[0056] 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 .

[0057] The cylinder head 1 includes attachment holes 34 for attaching the cylinder head 1 to the engine block 56. 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 56. 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.

[0058] The cylinder head 1 includes an intake passage 3 arranged on the intake side 11 of the cylinder head 1. The intake passage 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 passage 3 is also configured to allow a main gas fuel to be introduced into the intake passage 3 and further into the main combustion chamber 31. The cylinder head 1 also includes an exhaust passage 4 arranged on the exhaust side 12 of the cylinder head 1. The exhaust passage 4 is configured to discharge exhaust gas from the main combustion chamber 31.

[0059] The cylinder head 1 includes a first intake valve hole 5A and a second intake valve hole 5B arranged at an 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.

[0060] The cylinder head 1 includes first and second exhaust valve holes 6A, 6B arranged at the exhaust side 12 of the cylinder head 1. 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. Therefore, the cylinder head 1 may be provided with two exhaust valves 9.

[0061] 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 can also be configured to receive a pre-combustion chamber assembly.

[0062] 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 to form a region which is configured to cover the cylinders 2 in the mounted state of the cylinder head 1.

[0063] Extension 13 includes first and second push rod passages 14A, 14B. Each of push rod passages 14A, 14B is configured to allow push rod 15 to pass therethrough. In the mounted state of cylinder head 1, push rod passages 14A, 14B are located farther from the longitudinal center axis of cylinder 2 than attachment hole 34.

[0064] 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 47. If the cylinder head 1 is used in a V-type engine, the cams for the two groups of cylinders 2 of the engine can be arranged in the same camshaft. Figure 4 In the embodiment of the present invention, the engine includes a single camshaft configured to operate all the intake valves 8 and exhaust valves 9 of the engine. The push rods are spring biased against the cams. The push rod passages 14A, 14B collect lubricating oil from the valve actuation mechanism above the cylinder head 1 and direct the lubricating oil through the exhaust passage 4.

[0065] 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 manifolds 43, 44 to be attached to the extension 13 and to be in fluid communication with the exhaust passage 4. The push rod passages 14A, 14B are therefore 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 manifolds 43, 44 to be attached to the extension 13 by screws 36.

[0066] 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 that passes through an extension 13 of the cylinder head 1. The exhaust passage 4 merges into the common portion 4C before the push rod passages 14A, 14B.

[0067] 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 conduit 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.

[0068] 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 on both sides of the exhaust passage 4.

[0069] 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.

[0070] 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.

[0071] The cylinder head 1 includes at least one coolant outlet 21, 22A, 22B, which is 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 includes 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 part 16A of the coolant cavity 16. The cylinder head 1 also includes 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 part 16B of the coolant cavity 16.

[0072] The extension 13 of the cylinder head 1 is configured for attaching a coolant module 23, which is configured to receive coolant from the coolant cavity 16. The cylinder head 1 includes threaded attachment holes for allowing the coolant module to be attached to the cylinder head 1 by screws 57. The coolant module 23 is arranged to receive coolant via the coolant outlets 21, 22A, 22B of the cylinder head 1. The coolant module 23 forms a thermal barrier below the exhaust manifold 43. The construction and function of the coolant module 23 will be explained in more detail further below.

[0073] 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 .

[0074] The engine comprises at least one exhaust manifold 43, 44 into which the exhaust gases from the cylinders 2 of the engine are conducted. The in-line engine shown in the figure comprises a single exhaust manifold 43. Thus, the exhaust ducts 4 of all cylinder heads 1 of the engine are connected to the same exhaust manifold 43.

[0075] exist Figure 4In the embodiment of the V-type engine, the V-type engine includes a first exhaust manifold 43 for the first bank 41 of cylinders and a second exhaust manifold 44 for the second bank 42 of cylinders. Therefore, the cylinders 2 of the first bank 41 are connected to the first exhaust manifold 43, and the cylinders 2 of the second bank 42 are connected to the second exhaust manifold 44. The exhaust manifolds 43, 44 are arranged between the two banks 41, 42 of cylinders in the lateral direction of the engine. In the vertical direction, the exhaust manifolds 43, 44 are arranged above the engine block 56.

[0076] Each exhaust manifold 43, 44 comprises a longitudinal portion 45. The axial direction of the longitudinal portion 45 is parallel to the longitudinal direction of each row 41, 42 of cylinders. Each exhaust manifold 43, 44 also comprises a plurality of branches 46 connecting the longitudinal portion 45 to the exhaust duct 4 of the cylinder head 1. The number of branches 46 in the exhaust manifold 43, 44 is equal to the number of cylinders 2 to which the exhaust manifold 43, 44 is connected.

[0077] In the embodiment of the figures, each exhaust manifold 43, 44 comprises a plurality of exhaust manifold modules, each module comprising a section of a longitudinal portion 45 of the exhaust manifold 43, 44 and exactly one branch 46 of the exhaust manifold 43, 44. In the embodiment of the figures, a section of the longitudinal portion 45 of each exhaust manifold module is attached to an adjacent exhaust module by means of an intermediate piece 55. The intermediate piece 55 may be flexible to reduce vibrations.

[0078] In the embodiment of the figures, each branch 46 is attached to the respective cylinder head 1 by means of a mounting flange 53. The mounting flange 53 is attached to the cylinder head 1 by means of screws 58.

[0079] The coolant module 23 is arranged to receive coolant from the coolant chamber 16 of the cylinder head 1. The coolant module 23 comprises a lower portion 23A which is arranged to protrude from the cylinder head 1 in a direction perpendicular to the longitudinal direction of the row 41, 42 of cylinders, below the respective branch 46 of the exhaust manifold 43, 44. Thus, the lower portion 23A of the coolant module 23 protrudes laterally outward from the cylinder head 1, i.e. in a direction away from the cylinder head 1. The projection of the lower portion 23A of the coolant module 23 in a horizontal plane extends from the cylinder head 1 in a direction perpendicular to the longitudinal direction of the row 41, 42 of cylinders to at least the same distance as the projection of the branch 46 of the exhaust manifold 43, 44 on the same plane. Thus, the outermost point of the lower portion 23A of the coolant module 23 is at least as far away from the respective cylinder 2 of the engine in the lateral direction of the engine as the farthest point of the junction between the branch 46 of the exhaust manifold 43, 44 and the longitudinal portion 45. Alternatively or additionally, the projection of the lower portion 23A of the coolant module 23 in the horizontal plane may extend from the cylinder head 1 to at least the same distance as the longitudinal center axis of the longitudinal portion 45 of the exhaust manifold 43, 44. Figure 21 shows an embodiment in which the outermost point of the lower portion 23A of the coolant module 23 is substantially aligned with the longitudinal center axis of the longitudinal portion 45 of the exhaust manifold 43. In a V-type engine, the projection of the lower portion 23A of the coolant module 23 may extend further from the cylinder head 1 than the corresponding exhaust manifold 43, 44, such as Figure 4 shown.

[0080] In a V-type engine, both banks 41, 42 of cylinders are provided with a coolant module. The coolant modules 23 may be identical to each other.

[0081] In the embodiment of the figures, each cylinder 2 of the engine is provided with its own coolant module 23. Thus, a lower portion 23A of the coolant module 23 is arranged below each branch 46 of the exhaust manifolds 43, 44. The lower portion 23A of the coolant module 23 of each row 41, 42 of cylinders forms a substantially continuous thermal barrier below the respective exhaust manifold 43, 44. Instead of providing each cylinder 2 of the engine with its own coolant module 23, the engine may be provided with a coolant module 23 comprising a lower portion 23A extending in the longitudinal direction of the exhaust manifolds 43, 44 below at least two branches 46 of the exhaust manifolds 43, 44. Alternatively or additionally, the coolant module 23 may comprise two or more separate lower portions 23A.

[0082] According to an embodiment of the present invention, in a V-type engine, the size of the lower portion 23A of the coolant module 23 of the first row 41 of cylinders and the second row 42 of cylinders is determined so that the gap 48 between the lower portion 23A of the coolant module 23 of the first row 41 of cylinders and the lower portion 23A of the corresponding coolant module 23 of the second row 42 of cylinders is at most 20 mm. According to an embodiment of the present invention, the gap 48 is at most 10 mm, preferably at most 5 mm. However, the gap 48 is preferably at least 2 mm. Figure 4 As shown, the coolant modules 23 arranged opposite to each other form an almost continuous heat barrier in the lateral direction of the engine. The small gap 48 between the opposite coolant modules 23 does not allow significant heat radiation through the lower portion 23A of the coolant module 23, but allows thermal expansion of the components.

[0083] In the embodiment of the drawings, the cooling liquid module 23 further includes a first side portion 23B extending upward from the lower portion 23A on a first side of the branch 46 of the exhaust manifold 43, 44 and a second side portion 23 extending upward from the lower portion 23A on a second side of the branch 46 of the exhaust manifold 43, 44. The side portions 23B, 23C are configured to allow cooling of the liquid flow from the lower portion of the cooling liquid module 23.

[0084] Lower portion 23A extends further from cylinder head 1 in the lateral direction of cylinder row 41, 42 than side portions 23B, 23C. Therefore, coolant flowing through side portions 23B, 23D of coolant module 23 does not significantly cool exhaust gases flowing in branches 46 of exhaust manifolds 43, 44.

[0085] In the embodiment of the figures, the coolant module 23 also comprises an upper portion 23 connecting the first side portion 23B to the second side portion 23C above the branch 46 of the exhaust manifold 43, 44. Thus, the coolant module 23 forms a collar around the branch 46 of the exhaust manifold. The upper portion 23D of the coolant module 23 collects the coolant from the side portions 23B, 23C. The lower portion 23A extends further away from the cylinder head 1 in the lateral direction of the row 41, 42 of cylinders than the upper portion 23D. Therefore, the coolant flowing through the upper portion 23D of the coolant module 23 does not significantly cool the exhaust gases flowing in the branch 46 of the exhaust manifold 43, 44.

[0086] The upper portion 23D of each coolant module 23 is arranged in fluid communication with the upper portion 23D of an adjacent coolant module 23 of the same row 41 , 42 of cylinders.

[0087] In the embodiment of the figures, the lower part 23A of the coolant module 23 protrudes from the cylinder head 1 in such a direction that the distance between the respective branches 46, 44 of the exhaust manifold 43 and the lower part 23A of the coolant module 23 increases towards those ends of said module 23 and said branches 46 which are located away from the respective rows 41, 42 of cylinders. In the case of the in-line engine of the figures, the lower part 23A of the coolant module 23 is substantially horizontal. The branches 46 of the exhaust manifold 43 extend obliquely upwards from the cylinder head 1. ... Figure 4 In the case of a V-type engine, the lower portion 23A of the coolant module 23 and the branches 46 of the exhaust manifolds 43, 44 both extend obliquely upward from the cylinder head 1, but the branches 46 of the exhaust manifolds 43, 44 extend at a greater angle. The space in the cylinder head 1 is limited, and the coolant module 23 therefore needs to be arranged close to the branches 46 of the exhaust manifolds 43, 44 in the cylinder head 1. The increased distance between the lower portion 23A of the coolant module 23 and the branches 46 of the exhaust manifolds 43, 44 helps to keep the cooling effect of the coolant module 23 on the exhaust gas to a minimum, thereby maintaining a high exhaust gas temperature.

[0088] In the embodiment of the drawings, the coolant module 23 is configured so that the projection of the coolant module 23 on the plane of the mounting flange 53 is located outside the mounting flange 53. Therefore, even when the coolant module 23 is attached to the cylinder head 1, the screws 58 that attach the mounting flange 53 to the cylinder head 1 can be accessed.

[0089] 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 is 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 is connected to the upper portion 16B of the coolant cavity 16 of the cylinder head 1.

[0090] In the embodiment of the drawings, each cylinder 2 of the engine is provided with its own coolant module 23. This reduces the number of different components required for engines with different cylinder configurations. However, a single coolant module 23 can also be used for two or more cylinders 2 of the engine.

[0091] The lower portion 23A of the coolant module 23 has an end face 54 that is positioned away from the corresponding 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 both V-type engines and in-line engines. 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 the heat shield 49 surrounding the exhaust manifold 43, such as Figure 2 shown.

[0092] exist Figure 4 In the embodiment of the engine includes a heat shield 49 extending from the coolant module 23 of the first bank 41 of cylinders to the coolant module 23 of the second bank 42 of cylinders above the exhaust manifolds 43, 44. An in-line engine may be provided with a similar heat shield. Figure 2 The heat shield 49 of the in-line engine is shown. The heat shield 49 extends from the end face 54 of the lower part 23A of the coolant module 23 around the longitudinal portion 45 of the exhaust manifold 43 to the upper side of the branch 46 of the exhaust manifold 43. Due to the presence of the coolant module 23, a heat shield is not required directly below the branch 46 of the exhaust manifold 43.

[0093] 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 piston engine, comprising a plurality of cylinders (2) arranged in at least one row (41, 42) of cylinders, each cylinder (2) being provided with a cylinder head (1), the cylinder head (1) comprising an exhaust passage (4) for exhausting exhaust gases from the cylinders (2) and comprising a cooling liquid chamber (16) through which a cooling liquid can circulate, the engine comprising at least one exhaust manifold (43, 44), the exhaust manifold (43, 44) having a longitudinal portion (45) extending in the longitudinal direction of the at least one row (41, 42) of cylinders and a branch (46) connecting the longitudinal portion (45) to the exhaust passage (4) of the cylinder head (1), wherein: The engine comprises at least one coolant module (23), the coolant module (23) being attached to a cylinder head (1) of the engine and being arranged to receive coolant from a coolant chamber (16) of the cylinder head (1), the coolant module (23) comprising at least a lower portion (23A), the lower portion (23A) being arranged to protrude from the cylinder head (1) below a corresponding branch (46) of the exhaust manifold (43, 44) in a direction perpendicular to the longitudinal direction of the at least one row (41, 42) of cylinders, and wherein a projection of the lower portion (23A) of the coolant module (23) on a horizontal plane extends from the cylinder head (1) in a direction perpendicular to the longitudinal direction of the at least one row (41, 42) of cylinders to at least the same distance as a projection of the branch (46) of the exhaust manifold (43, 44) on the plane.

2. The piston engine according to claim 1, wherein: The engine is a V-type engine, comprising a first bank (41) of cylinders, a second bank (42) of cylinders and at least one exhaust manifold (43, 44), wherein the exhaust manifold (43, 44) is arranged between the first bank (41) of cylinders and the second bank (42) of cylinders in a lateral direction of the engine.

3. The piston engine according to claim 2, wherein: The exhaust passage (4) of the cylinder head (1) of each bank (41, 42) of cylinders is arranged to open toward the other bank (41, 42) of cylinders, and the engine comprises at least one coolant module (23) attached to the cylinder head (1) of the first bank (41) of cylinders and at least one coolant module (23) attached to the cylinder head (1) of the second bank (42) of cylinders.

4. The piston engine according to claim 3, wherein: The coolant modules (23) of the first (41) cylinder bank and the second (42) cylinder bank are identical to each other.

5. The piston engine according to claim 3 or 4, wherein: The dimensions of the lower parts (23A) of the coolant modules (23) of the first row (41) of cylinders and the second row (42) of cylinders are determined so that the gap (48) between the lower parts (23A) of the coolant modules (23) of the first row (41) of cylinders and the lower parts (23A) of the corresponding coolant modules (23) of the second row (42) of cylinders is at most 20 mm.

6. The piston engine according to claim 5, wherein: The gap (48) is at most 10 mm, preferably at most 5 mm.

7. The piston engine according to claim 5 or 6, wherein: The gap (48) is at least 2 mm.

8. The piston engine according to any one of claims 3 to 7, wherein: The engine includes a heat shield (49) extending above the exhaust manifold (43, 44) from the coolant module (23) of the first bank (41) of cylinders to the coolant module (23) of the second bank (42) of cylinders.

9. The piston engine according to any one of claims 2 to 8, wherein: The engine comprises a first exhaust manifold (43) for the first bank (41) of cylinders and a second exhaust manifold (44) for the second bank (42) of cylinders.

10. A piston engine according to any one of the preceding claims, wherein: The lower part (23A) of the coolant module (23) protrudes from the cylinder head (1) in such a direction that the distance between the corresponding branches (46) of the exhaust manifolds (43, 44) and the lower part (23A) of the coolant module (23) increases towards those ends of the module (23) and the branches (46) which are farther from the at least one row (41, 42) of cylinders.

11. A piston engine according to any one of the preceding claims, wherein: The lower portion (23A) of the coolant module (23) includes at least one coolant inlet (50) arranged to receive coolant from the coolant cavity (16) of the cylinder head (1).

12. A piston engine according to any one of the preceding claims, wherein: The coolant module (23) further includes a first side portion (23B) and a second side portion (23C), wherein the first side portion (23B) extends upward from the lower portion (23A) on a first side of a branch (46) of the exhaust manifold (43, 44), and the second side portion (23C) extends upward from the lower portion (23A) on a second side of the branch (46) of the exhaust manifold (43, 44).

13. The piston engine according to claim 12, wherein: The lower portion (23A) extends further away from the cylinder head (1) in a lateral direction of the at least one row (41, 42) of cylinders than the side portions (23B, 23C).

14. A piston engine according to claim 12 or 13, wherein: The coolant module (23) includes an upper portion (23D) connecting the first side portion (23B) to the second side portion (23C) above a branch (46) of the exhaust manifold (43, 44).

15. The piston engine according to claim 14, wherein: The lower portion (23A) of the coolant module (23) extends further from the cylinder head (1) in the lateral direction of the at least one row (41, 42) of cylinders than the upper portion (23D).

16. A piston engine according to claim 14 or 15, wherein: The upper portion (23D) of the coolant module (23) comprises at least one coolant inlet (51) arranged to receive coolant from the cylinder head (1).

17. The piston engine according to claim 16, wherein: The upper portion (23D) of the coolant module (23) comprises at least two coolant inlets (51) arranged to receive coolant from the cylinder head (1).

18. A piston engine according to any one of the preceding claims, wherein: Each cylinder (2) of the engine is provided with its own coolant module (23).

19. The piston engine according to claim 18, wherein: Each cooling liquid module (23) is arranged to be in fluid communication with at least one adjacent cooling liquid module (23).

20. A piston engine according to any one of the preceding claims, wherein: Each branch (46) of the exhaust manifold (43, 44) is attached to the corresponding cylinder head (1) via a mounting flange (53), and the coolant module (23) is configured so that a projection of the coolant module (23) on the plane of the mounting flange (53) is located outside the mounting flange (53).

21. A piston engine according to any one of the preceding claims, wherein: The lower portion (23A) of the coolant module (23) has an end surface (54) that is away from the corresponding cylinder head (1), and the mutual angle between the end surface (54) and the axial direction of the corresponding cylinder (2) is 15 to 40 degrees, and the upper edge of the end surface (54) is farther away from the cylinder (2) than the lower edge.

22. The piston engine according to claim 21, wherein: The engine is a V-type engine, and the angle is substantially equal to the inclination angle of the cylinder (2) relative to the vertical direction.

23. A piston engine according to any one of the preceding claims, wherein: The cylinder head (1) includes an integral extension (13) formed on the exhaust side (12) of the cylinder head (1), the extension (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 the exhaust passage (4) being arranged to pass through the extension (13) between the first push rod channel (14A) and the second push rod channel (14B), and the coolant module (23) being attached to the extension (13) of the cylinder head (1).

24. A piston engine according to any one of the preceding claims, wherein: The exhaust manifold (43, 44) comprises a plurality of exhaust manifold modules, each module comprising a section of a longitudinal portion (45) of the exhaust manifold (43, 44) and a branch (46) of the exhaust manifold (43, 44).

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