KR20240093637A - On-site conversion of marine vessel powertrains - Google Patents

Abstract

The present invention relates to a field powertrain (2) of a marine vessel (1) provided with at least one propulsion powertrain configured to provide thrust for operating the vessel (1) at a first predetermined operating profile, such as design speed. The conversion relates to at least one powertrain (2) comprising a multi-cylinder two-stroke internal combustion piston engine (6), a propeller (10) and a shaft arrangement mechanically connecting the propeller (10) and the engine (6). and configuring the at least one powertrain (2) to provide thrust to operate the vessel (1) in a second operating profile with less power requirements than the first operating profile. do,
- the existing combustion chamber components 200, including at least the cylinder sleeve 114, the cylinder cover 116, the piston 112 and the piston rod 110, are used in the engine of the at least one powertrain (2). (6) is removed from,
- new combustion chamber components 200' are assembled to the engine 6 of the at least one powertrain 2 and are equipped with a new cylinder sleeve (114) having a smaller bore diameter than the existing cylinder sleeve 114 The new combustion chamber components including 114') are configured to produce a higher specific power than the old combustion chamber components 200 removed.

Description

On-site conversion of marine vessel powertrains

The present invention relates to powertrain field conversion of a marine vessel provided with at least one propulsion powertrain configured to provide thrust for operating the vessel in a first predetermined operating profile, wherein the at least one powertrain comprises a multi- It includes a cylinder two-stroke internal combustion piston engine, a propeller, and a shaft arrangement mechanically connecting the propeller and the engine.

Many existing large ocean-going vessels are equipped with large two-stroke main engines or even a single two-stroke main engine, which burns fossil fuels such as heavy oil and gas in the form of boil-off gas from the ship's cargo tanks. It operates by combustion of Such original engines, which have a significant operating life and run on traditional fuels, are likely to deliver significant emissions compared to current more stringent emission standards. Recently, interest in more environmentally friendly maritime transportation has been increasing. One of the most effective ways to reduce emissions as well as fuel consumption when operating these vessels is to reduce their speed. However, the ship's deceleration speed below the ship's original design speed shifts the operation of the powertrain, particularly the ship's engines, into areas of inefficiency.

In ships with large two-stroke engines, the propellers are usually connected directly to the engine without a reduction gear, so that their rotational speeds are equal to each other. Accordingly, a slower speed of the vessel results in a slower rotational speed of the engine, which may no longer be at the engine's optimal operating speed.

The object of the present invention is to provide a field conversion of the powertrain of a marine vessel, providing a new, slower design speed for the vessel and optimized operation of the engines of the powertrain.

The object of the invention can be achieved substantially as set forth in the independent claims and in other claims that describe details of different embodiments of the invention.

According to one embodiment of the present invention, there is provided a powertrain field conversion of a marine vessel provided with at least one propulsion powertrain configured to provide thrust for operating the vessel at a first predetermined operating profile, such as design speed. wherein the at least one powertrain includes a multi-cylinder two-stroke internal combustion piston engine, a propeller and a shaft arrangement mechanically connecting the propeller and the engine, the transition being configured to operate the vessel in a second operating profile. configuring at least one powertrain to provide thrust for the engine, wherein existing combustion chamber components, including at least a cylinder sleeve, a cylinder cover, a piston, and a piston rod, are removed from an engine of the at least one powertrain, and the new combustion chamber components include a cylinder sleeve, a cylinder cover, a piston, and a piston rod. Combustion chamber components are assembled to an engine of at least one powertrain, wherein the new combustion chamber components include a new cylinder sleeve with a smaller bore diameter than the existing cylinder sleeve and have a higher bore diameter than the old combustion chamber components removed. It is configured to generate a specific power.

In this way, the engine is operating in a fuel efficient manner in the new situation of the second operating profile. The engine's operating conditions can remain favorable for complete fuel combustion due to the smaller bore diameter.

According to one aspect of the invention, the existing engine of the at least one propulsion powertrain is configured to provide thrust to move the vessel at a first predetermined design speed and is adapted to travel at a first rotational speed, wherein the transition is It further includes that the engine of the powertrain is adapted to run at a second rotation speed that is lower than the first rotation speed.

This has the effect that the optimal operating window of the converted engine with high (thermal) efficiency is now matched to the new power level and rotational speed range required by the powertrain to move the vessel to the new second design speed.

According to one aspect of the invention, the conversion includes configuring at least one propeller of the powertrain to accommodate a change in operating profile and/or rotational speed, wherein the new combustion chamber components correspond to the propeller curve of the configured propeller. Provides new torque-speed characteristics to the engine.

This has the effect that the cylinder-specific spatial combustion volume and combustion stages within it are optimized to respond to new operating situations, so that higher thermal efficiencies can be achieved in the conversion of fuel chemical energy into mechanical energy at the new power levels required.

According to one aspect of the present invention, constructing the propeller may include assembling a new propeller or propeller blades to the hub of an existing propeller.

This also means that the lower design speed of the ship and/or any other changes made to the hull geometry of the ship will affect the rotational speed of the propellers and will result in a new second design speed affecting the operation of the propeller arrangement. It provides the effect of optimizing the efficiency of the array.

According to one aspect of the invention, constructing the propeller includes increasing the diameter of the propeller.

This provides the effect of not only lowering the rotation speed of the propeller below the original first rotation speed, but also improving the overall efficiency of the propeller at the new design speed of the ship.

According to one aspect of the invention, the new combustion chamber components further include exhaust valves and fuel injectors.

This has the effect of optimizing gas exchange, cylinder-specific combustion stages and fuel delivery to meet the new target power levels required with high thermal efficiency.

According to one aspect of the invention, the new combustion chamber components are pre-assembled as a powerpack which is then assembled into the engine as an entity.

This provides better logistics for delivering needed new components to the conversion location and faster delivery of assembly tasks and processes during conversion.

According to one aspect of the invention, conversion includes replacing or configuring the fuel injection control system of the engine to reduce the amount of fuel injection on each power stroke, at least when the vessel is in service and traveling at its design speed.

This has the effect of ensuring that the control of fuel introduction to each cylinder matches the engine's new operating profile, providing highly efficient combustion.

According to one aspect of the invention, the reduction ratio of the mechanical shaft arrangement connecting the propeller and the engine is not changed in conversion.

This lowers costs and shortens changeover times by minimizing the number of components and assemblies that need to be changed. Typically, such mechanical arrangements have a long expected service life that would otherwise require no modifications, and utilizing a long service life is generally environmentally friendly.

According to one aspect of the invention, the new combustion chamber components are attached to the engine block via an adapter block, the adapter block having first attachment means compatible with the attachment means of the engine block and first attachment means compatible with the new combustion chamber components. and a second attachment means.

This has the effect of reducing the cost and overall requirements of conversion operations, tools and labor, as significant modifications requiring for example bulk on-site alteration of the engine block are not required during conversion.

According to one aspect of the invention, the cylinder cover of the new combustion chamber is attached to the adapter block, and the adapter block is attached to the engine block.

This provides the effect of being able to build an array in a power pack with the aforementioned advantages.

According to one aspect of the invention, a cylinder cover of new combustion chamber components has a first set of openings for a first set of fuel injectors configured to inject a first fuel into the combustion chamber and a second fuel into the combustion chamber. and at least a second set of openings for a second set of fuel injectors configured to.

This provides the effect that a conversion based on the use of a new cylinder cover prepares the engine for additional alternative fuels such as gaseous fuels and the engine can be converted to a multi-fuel engine during the conversion or later. Adding a second set of injectors later does not require significant disassembly of the engine, but the injectors can be easily added or serviced.

According to one aspect of the invention, the stroke length of the piston of the engine does not change when switching.

This has the effect of lowering the cost and effort required by conversion by retaining the original crankshaft, which is a major and expensive component.

According to one aspect of the invention, the engine parameters for a vessel operating at design speed after conversion are:

Maximum cylinder pressure: 250 bar

Stroke to Bore Ratio: 3.5 - 4.5

Design rpm range: 70-105 rpm

Design power levels 2000-3200 kW/cylinder

According to one aspect of the invention, upon conversion, the bore diameter of the sleeve is reduced by at least 20%.

Increasing the pressure within the cylinder provides increased efficiency through improved combustion and reduced heat loss. And, due to the smaller bore diameter stresses caused in the bearings by the increased pressure, it is still within acceptable levels for older engines.

The engine is a crosshead engine and, according to one aspect of the invention, upon conversion new compression shims or shims are placed between the crosshead and the piston rod during assembly to make up the clearance volume of the cylinder.

This provides an effect gain setting for providing high compression ratios.

According to one aspect of the invention, conversion includes replacing or configuring a turbocharger in an engine.

This provides the effect of matching the air pressure to the new environment.

According to one aspect of the invention, after transitioning from the bottom dead center position of the piston, the piston is entirely below the air ports.

By converting according to the invention, appropriate engine performance is achieved - and carbon emissions are therefore minimized - because the powertrain is set to match the new operating profile of the vessel. Additionally, a reconfiguration of the combustion is carried out to suit current and future power requirements, and a reduction in bore diameter results in improved combustion efficiency and reduced heat losses.

After converting an existing engine with a new combustion chamber and a new and/or reconfigured fuel injection control system, the engine meets the torque-speed characteristic requirements set by the reconfigured propeller.

Advantageously, the torque required after conversion is improved by higher cylinder maximum pressure/MEP-ratio and lower heat losses after ignition of the fuel, supported by higher mean effective pressure (MEP) and higher compression ratio, resulting in improved fuel consumption. is created with Therefore, the mean effective pressure (MEP) at the time of conversion is increased, and the maximum cylinder pressure/MEP-ratio after ignition of the fuel is increased compared to the existing engine.

The exemplary embodiments of the invention disclosed in this patent application should not be construed as limiting the applicability of the appended claims. The verb “to include” is also used in this patent application as an open limitation so as not to exclude the presence of unrecited features. The features recited in the dependent claims can be freely combined with each other unless explicitly stated otherwise. The novel features considered to be characteristic of the invention are pointed out with particularity in the appended claims.

In the following, the present invention is explained with reference to the accompanying exemplary schematic drawings.
Figure 1 schematically shows a large marine vessel.
Figure 2 shows an exemplary propeller curve of a ship.
Figure 3 shows a cross-sectional view of an existing engine in a ship.
Figure 4 shows the situation after the first stage of conversion according to one embodiment of the present invention.
Figure 5 shows a situation where combustion chamber components are external to the engine.
Figure 6 shows the situation after installing new combustion chamber components on an existing engine.
Figure 4 shows the situation after the first stage of conversion according to one embodiment of the present invention.
7 shows old and new combustion chamber components.
Figure 8 shows an adapter block according to one embodiment of the invention.
Figure 9 shows a new cylinder cover according to one embodiment of the invention.

Figure 1 schematically shows a large marine vessel (1) equipped with at least one propulsion powertrain (2). This is a side view of the vessel and is therefore not shown in the drawing, which could be as an auxiliary propulsion system in vessel 1 or other similar or different types of powertrains arranged in parallel. The original ship hull 4 has a specific size and shape resulting in specific power demands to move the ship at its original design speed. Here, the term “design speed” should be understood to mean the speed considered to be the typical and effective operating speed of a vessel during long ocean voyages. This design speed may deviate somewhat downward from the maximum hull speed dictated by the length of the ship's waterline. Powertrain (2) is configured to provide thrust to operate the vessel at its design speed. More generally, it can be said that the vessel has a first predetermined operating profile requirement of the powertrain (2). The powertrain (2) is a multi-cylinder two-stroke crosshead mechanically connected to the propeller (10) by a propeller shaft (8) in such a way that the propeller rotates at the same speed as the engine, i.e. with a so-called gear ratio of 1:1. Includes engine (6). For example, the design speed may be set at 25 knots. Such speeds can be achieved, for example, by the well-known large two-stroke engines. The engine is equipped with a control system 12 that, among other functions of the engine, controls fuel injection to the cylinders of the engine 6.

Figure 2 discloses an exemplary propeller curve A of a vessel 2 showing the power required per cylinder of the engine 6 to achieve each rotational speed of the propeller. Therefore, the horizontal axis represents the speed of the engine and propeller (revolutions per minute), and the vertical axis represents the cylinder-unit power (kW/cylinder). The original design speed of vessel 1 corresponds to point S1 on the curve, which is obtained with a propeller and engine speed of approximately 100 rpm, which is approximately 5500 kW power per cylinder of the engine, which is the original design nominal power of each cylinder of the engine. need. Operating the vessel at its design speed may be referred to as operation in the first operating profile. When it is desired to reduce the cruising speed of vessel 1 to a speed lower than the design speed, for example 20-23 knots, the propeller speed is reduced to the cruising speed corresponding to point S2 in curve A. Point S2 will be achieved by operating the existing powertrain at approximately 87 rpm, requiring only approximately 3300 kW per cylinder to move the vessel at lower speeds. As an immediate effect, this will also result in a reduction in fuel consumption. However, point S2 may no longer be optimal for the existing powertrain (2). In some cases, details of the ship's hull, for example a bulb protruding from the ship's bow just below the waterline, may also not be optimal for the new speed. In conclusion, the new lower speed alone, as well as other potential changes in the vessel that affect the new operating profile, will be inconsistent with the characteristics of the original powertrain. Therefore, according to the invention, an on-site powertrain conversion takes place with the powertrain in order to adapt the powertrain 2 to better meet the demands of the new operating profile of the vessel. In this application, the term operating profile of a vessel refers to one or more of the following situations: The most important issue is the ship's actual cruising speed, but other influencing circumstances are any changes to the ship's hull, such as modifications to the bulbous prow, or ballast management of the ship or hull array, which affects the operation of the propellers. There may be changes to

Referring now to Figures 3-6, in-situ conversion of powertrains in a large marine vessel as shown in Figure 1 is described below.

Figure 3 shows a cross-sectional view of an older, existing engine 6 within a vessel 1. Engine 6 is a large two-stroke multi-cylinder engine. The main parts of the engine 6 include an engine block 100, a crankshaft 102 rotatably supported on the engine block 100, a connecting rod 104, and a crosshead arranged to be guided by a guide 108. (106), piston rod (110), piston (112) and cylinder sleeve (114), cylinder cover (116), exhaust valve (118), exhaust manifold (120) and supercharger (122), typically turbocharger am. The parts that form the combustion chamber, such as the cylinder sleeve 114, cylinder cover 116, piston 112, and piston rod 110, may be generally referred to as combustion chamber components 200. It should be understood that there are various auxiliary parts operably associated with combustion chamber components such as exhaust valves and their actuation systems, fuel injection systems, cooling and lubrication systems. Although not specifically shown in the drawing, there is a flow path (arrow) 126 arranged within the engine to scavenge air between the turbocharger 122 and the scavenge air space 124 within the engine. The scavenging flow passage 126 may include, for example, an air cooler. The cylinder sleeve 114 is provided at its lower part with air ports 128 that open into the air space 124 of the engine. The cylinder cover 116 assembled on top of the cylinder sleeve 114 is provided with fuel injection nozzles (not shown). An engine may typically include 6-14 cylinders, but of course the practical application of the invention is not limited to any particular number of cylinders within the engine.

Field conversion of powertrain (2) may constitute powertrain (2), or, if the vessel comprises more than one powertrain, each power train to provide thrust for operating the vessel in a second operating profile. Including constructing train (2).

Figure 4 shows the situation after the first conversion step. It should be understood that in practice it may be necessary to perform some preliminary and auxiliary work prior to the first step. The first conversion step involves removing the existing combustion chamber components 200 from the engine 6. In relation to application, "old" and "old" refer to the situation and parts within the engine before conversion and "new" and "conversion" to the situation after conversion and parts changed or reconfigured during conversion. At 4a of the figure, the existing combustion chamber components 200 disassembled from the engine 6 are schematically shown. Although combustion chamber components 200 are shown here as individually disassembled, in existing engines, these components are typically partially removed. The old crankshaft, crosshead and connecting rods will remain the same after conversion, but any parts that have worn out can be naturally inspected, changed or serviced.

Figure 5 shows a situation where the combustion chamber components are external to the engine 6 and new combustion chamber components 200' are ready for assembly, as shown in 5a of the figure. Figure 5 also shows the invention in which the new combustion components 200' are pre-assembled to the appropriate extent as a power pack and then this power pack is assembled into the engine 6 as one larger entity as shown in 5a of the figure. Initiate additional and alternative improvements. Although it may be advantageous in some practical applications, it is not an essential feature of the invention. The stroke length of the engine's pistons during conversion does not change because the engine uses the old crankshaft and connecting rods after conversion.

In the next conversion step, new combustion chamber components 200' are assembled into engine 6. Additionally, if the vessel (1) contains more than the powertrain (2), a switch is made to the engine (1) of the powertrain (2). Figure 6 shows the situation after installing new combustion chamber components 200' to an existing engine 6.

Figure 7 shows old combustion chamber components 200 and new combustion chamber components 200' side by side. The connections of the components to the engine 6 can be shown as block 100 and the exhaust manifold 120 is shown in the figure as a dashed line. An important feature of the conversion is that the new cylinder sleeve 114' of the new combustion chamber components 200' has a smaller bore diameter than the existing cylinder sleeve 114. This improves the combustion efficiency of the fuel because the amount of fuel injected during the cycle is now smaller and the smaller diameter of the combustion chamber results in more complete combustion. In the figure, it can also be seen that the air ports 128' in the new cylinder sleeve 114' are further from the crankshaft, i.e. higher horizontally than in the old cylinder sleeve 114. Additionally, the new air ports 128' are axially longer in the cylinder sleeve than the air ports in the old cylinder sleeve 114 to accommodate a much higher compression ratio. At the bottom dead center position of the piston, the piston is completely below the air ports 128'.

The new combustion chamber components 114' are configured to adapt combustion to a new operating profile where the vessel speed is less than the original design speed of the vessel 1 and the propeller rotation speed of the powertrain is less than the original design rotation speed. In particular, the new combustion chamber components 114' are configured to produce higher specific power than the older combustion chamber components 200. The engine 6 after conversion meets the torque speed characteristic requirements of the existing propeller and possibly the rebuilt propeller. The torque of the engine 6 after conversion is improved by a higher maximum cylinder pressure/MEP-ratio and lower heat losses through the cylinder walls after ignition of the fuel, supported by a higher mean effective pressure (MEP) and a higher compression ratio. This results in fuel efficiency (reduced fuel consumption).

A significant change is observed in the new cylinder sleeve 114' within the new combustion chamber components 200', which has a smaller bore diameter than the existing cylinder sleeve 114, and the diameter of the new piston 112'. are smaller than the spherical piston 112, respectively. Additionally, the new combustion chamber components further include new exhaust valves 118' and in some cases new fuel injectors 130', or at least conversion of older fuel injectors to accommodate them with new operating profiles. Accommodation of older fuel injectors requires the fuel injection control system of engine 6 (Figure 1 - 12) to reduce the fuel injection quantity on each power stroke, at least when the vessel is in service and traveling at its design speed. This may include replacing or configuring. Field conversion may also involve more radical modifications of the fuel injection system. For example, modifying the fuel supply system to the extent necessary for combustion of different fuels.

Upon conversion, the exhaust gas inlets 121 to the exhaust manifold 120 remain in their existing positions and the new combustion chamber components 200' are connected to the exhaust gas outlets of the new combustion chamber components 200' ( 123') is positioned vertically in a position where it can be directly attached to the exhaust gas inlets 121. For that purpose, an adapter block 132' is provided to receive a new cylinder sleeve 114' in the block 100 of the engine 6. Matching the positions of the exhaust connections described above is an important feature that significantly reduces the number and cost of changes required for heavy exhaust systems on ships. An embodiment of adapter block 132' is shown in FIG. 8. The adapter block is used to attach and seal the new combustion chamber components 200' to the engine block. Adapter block 132' includes first attachment means 136' compatible with attachment means 134 of engine block 100 and second attachment means 140' compatible with new combustion chamber components. . More precisely, the engine block 100 is provided with holes 134 threaded around the opening for the sleeve in the block 100, which are arranged in a first pattern. The first pattern follows the pattern of the attachment bolts of the spherical cylinder cover 116. Adapter block 132' is a substantially circular disk-shaped member with an opening to accommodate new cylinder sleeve 114'. The adapter block 132' is provided with through holes 136' parallel to and around the opening for the new sleeve 114'. The through holes 136' are of the same pattern as the bolts of the spherical cylinder cover 116. In this way, the adapter block 132' can be attached by new bolts 138' to the engine block using the threaded holes for the old cylinder cover 116. The new cylinder cover 116' is then attached to the adapter block 132'. For this purpose, the adapter block 132' is provided with holes 140' threaded around the opening for the sleeve in the block 100, which are arranged in a second pattern. The second pattern matches the pattern of attachment bolts of the new cylinder cover 116', so that the new cylinder cover 116' can be attached to the adapter block 132'. In some practical cases, the adapter block 132' may be an integral part of the new cylinder sleeve 114'.

The vertical position of the new smaller diameter cylinder sleeve 114' is positioned in the correct vertical position by using the adapter block 132. The compression ratio is fine-tuned during conversion by using a compression shim or shims 148' placed between the crosshead and piston rod during assembly to properly configure the clearance volume of the cylinder. When the piston is at its bottom dead center, the position of the piston relative to the air ports 128' also has a full thickness effect in addition to the clearance volume of the cylinder.

An example of changed parameters of the engine in a successful conversion of a two-stroke engine according to the invention:

In this example the pressure within the cylinder is significantly increased, providing increased efficiency and improved combustion. Thanks to the reduced bore diameter, higher pressures produce forces on the older engine's power components that are well within the design range of the original engine. Smaller bore diameter reduces combustion heat loss.

Even though the bore diameter becomes smaller after conversion, the compression ratio increases, mostly because the swept volume of the combustion chamber becomes smaller. As can be seen upon conversion, the bore diameter of the sleeve is reduced by at least 20%. Typically, the new bore diameter is selected with the required piston diameter and average effective pressure to produce specific torque-speed characteristics that match the propeller curve in the changed operating profile. Additionally, the MEP produced is dependent on the amount of fuel injected per cycle, which is limited by the engine's stroke and combustion chamber component temperatures. Referring to the above example (table), if a 620 mm bore is considered, the MEP level will be higher, and therefore higher component temperatures, and consequently higher cylinder maximum pressure after ignition of the fuel, resulting in higher torque speed and target brake- Will meet specific fuel consumption. Therefore, a 620 mm cylinder bore would be too small. Preferably, the engine has the following characteristics after conversion:

Stroke to Bore Ratio: 3.5 - 4.5

Design rpm range: 70-105 rpm

Design power range: 2000-3200 kW/cylinder

The transition is a change in the operating profile and/or rotational speed of the engine 6 to provide the engine 6 with new torque-speed characteristics corresponding to the propeller curve of the propeller on which the new combustion chamber components 200' are configured. When this conversion involves configuring the propeller 10 of the powertrain 2 to accommodate, the vessel can be much more efficient in terms of operation. Advantageously, the propeller 10 is reconfigured so that its diameter is increased. Constructing a propeller can be accomplished by assembling a new propeller or propeller blades to the hub of an existing propeller. The mechanical shaft arrangement connecting the propeller to the engine includes a 1:1 reduction ratio that does not change favorably when switching.

According to another modification of the invention, the cylinder cover 116' of the new combustion chamber components 200' optionally includes two sets of openings for fuel injectors as shown in Figure 9. The cylinder cover is provided with openings 140' for attachment bolts of the new cylinder cover 116' and a centrally located exhaust valve port 142'. The cylinder cover 116' has a first set of openings 144' for a first set of fuel injectors configured to inject a first fuel into the combustion chamber and a second set of openings 144' configured to inject a second fuel into the combustion chamber. and at least a second set of openings 146' for fuel injectors. During the changeover, one of the sets of said openings is plugged if the engine is configured to operate only on one fuel and the other set of openings is provided with respective fuel injectors. When the engine is configured to operate with two different fuels, the first set of openings 144' is provided with a first set of fuel injectors and the second set of openings 146' is provided with a second set of fuel injectors. Fuel injectors are provided. The second set of openings 146' may also be used in connection with future fuel switching. Fuels currently considered as available candidates are, for example, methanol, LNG or ammonia. The second set of openings 146' are arranged to allow installation of fuel injectors without disassembling the cylinder cover. Methanol offers simple handling and storage, reliable combustion, and nearly carbon-neutral power (when manufactured using renewable electricity and captured carbon), making it a very attractive fuel for decarbonizing powertrains. LNG is currently an economical and sustainable fuel that reduces environmental risks and harmful emissions. Ammonia is also an attractive fuel because, for example, it does not emit CO2 when burned.

Although the invention has been described herein by way of example in connection with what are currently considered the most preferred embodiments, it will be apparent to those skilled in the art that, with technological progress, the basic idea of the invention can be implemented in many ways. The present invention and its embodiments are not limited to the examples and samples described above, and various modifications are possible according to the scope of the patent claims and their legal equivalents. Detailed descriptions mentioned in connection with any embodiment above may be used in connection with another embodiment if such combinations are technically feasible.

1: Large ship
2: Propulsion powertrain
4: hull
6: Multi-cylinder two-stroke crosshead engine
8: propeller shaft
10: propeller
12: control system
100: Engine block
102: crankshaft
104: connecting rod
106: cross head
108: Guide
110, 110': Piston rod
112, 112': Piston
114, 114': Cylinder sleeve
116, 116': Cylinder cover
118, 118': exhaust valve
120: exhaust manifold
122: Supercharger
123': Exhaust gas outlet
124: scavenging air space
126: flow path
128, 128': air ports
130': New fuel injectors
132': adapter block
134: Threaded holes
136': first attachment means
138': New Bolts
140': second attachment means
142': Exhaust valve port
144': first set of openings
146': Second set of openings
148' : Sim or Sims
200: Spherical combustion chamber components
200': New combustion chamber components

Claims (18)

A powertrain (2) of a marine vessel (1) provided with at least one propulsion powertrain configured to provide thrust for operating the marine vessel (1) at a first predetermined operating profile, such as a design speed -situ) As a transition,
The at least one powertrain (2) includes a multi-cylinder two-stroke internal combustion piston engine (6), a propeller (10) and a shaft arrangement mechanically connecting the propeller (10) and the engine (6), ,
Said switching comprises configuring said at least one powertrain (2) to provide thrust for operating said watercraft (1) in a second operating profile with less power requirements than said first operating profile,
- the existing combustion chamber components 200, including at least the cylinder sleeve 114, the cylinder cover 116, the piston 112 and the piston rod 110, are used in the engine of the at least one powertrain (2). (6) is removed from,
- New combustion chamber components 200' are assembled on the engine 6 of the at least one powertrain 2 and are equipped with a new cylinder sleeve (114) having a smaller bore diameter than the existing cylinder sleeve 114. Powertrain (2) field conversion, wherein the new combustion chamber components comprising 114') are configured to produce higher specific power than the removed old combustion chamber components 200. According to claim 1,
The existing engine (6) of the at least one propulsion powertrain (2) is configured to provide thrust for moving the vessel (1) at a first predetermined design speed and is adapted to run at a first rotational speed; , Characterized in that the changeover further comprises adapting the engine (6) of the powertrain (2) to run at a second rotational speed lower than the first rotational speed. The method of claim 1 or 2,
The conversion includes configuring the propeller 10 of the powertrain 2 to accommodate a change in operating profile and/or rotational speed, wherein the new combustion chamber components 200' are of the configured propeller. Field conversion of the powertrain (2), characterized in that it provides new torque-speed characteristics of the engine (6) corresponding to the curve. According to claim 4,
Powertrain (2) field conversion, characterized in that constructing the propeller (10) includes assembling a new or constructed propeller (10) or propeller blades to the hub of an existing propeller. The method of claim 4 or 5,
Field conversion of the powertrain (2), characterized in that configuring the propeller (10) includes increasing the diameter of the propeller (10). The method according to any one of claims 1 to 5,
Powertrain (2) field conversion, characterized in that the new combustion chamber components 200' further include an exhaust valve 118' and fuel injectors 130'. The method according to any one of claims 1 to 6,
Field conversion of the powertrain (2), characterized in that the new combustion chamber components (200') are pre-assembled as a powerpack assembled on the engine (6) as an individual. The method according to any one of claims 1 to 7,
Conversion includes replacing or configuring the fuel injection control system 12 of the engine 6 to reduce the fuel injection quantity in each power stroke, at least when the vessel 1 is traveling at its design speed in use. Characterized in that, powertrain (2) field conversion. The method according to any one of claims 1 to 8,
Field conversion of the powertrain (2), characterized in that the reduction ratio of the mechanical shaft arrangement connecting the propeller (10) and the engine (6) remains the same during conversion. The method according to any one of claims 1 to 9,
The new combustion chamber components 200' include a first attachment means 136' compatible with the attachment means of the engine block 100 and a second attachment means 136' compatible with the new combustion chamber components 200'. Field conversion of the powertrain (2), characterized in that it is attached to the engine block (100) via an adapter block (132'), comprising attachment means (140'). According to claim 10,
Characterized in that the cylinder cover (116') of the new combustion chamber components (200') is attached to the adapter block (132'), and the adapter block is attached to the engine block (100). (2) On-site conversion. The method according to any one of claims 1 to 11,
The cylinder cover 116' of the new combustion chamber components 200' has a first set of openings 144' for a first set of fuel injectors configured to inject first fuel into the combustion chamber. and at least a second set of openings (146') for a second set of fuel injectors configured to inject a second fuel into the combustion chamber. The method according to any one of claims 1 to 12,
Field conversion of the powertrain (2), characterized in that the stroke length of the piston of the engine (6) does not change during the conversion. The method according to any one of claims 1 to 13,
Field conversion of the powertrain (2), characterized in that the engine parameters for the vessel (1) traveling at design speed after the conversion are as follows.
Maximum cylinder pressure: 250 bar
Stroke to Bore Ratio: 3.5 - 4.5
Design rpm range: 70-105 rpm
Design power levels 2000-3200 kW/cylinder The method according to any one of claims 1 to 14,
(2) Field conversion of the powertrain, characterized in that during said conversion, the bore diameter of said sleeve is reduced by at least 20%. The method according to any one of claims 1 to 15,
The engine 6 is a crosshead engine 6 and upon conversion a new compression shim or shims 148' is installed between the crosshead 106 and the piston rod 110' during assembly to configure the clearance volume of the cylinder. (2) On-site conversion of the powertrain, characterized in that it is placed in. The method according to any one of claims 1 to 16,
Field conversion of the powertrain (2), characterized in that the conversion includes replacing or constructing a turbocharger of the engine (6). The method according to any one of claims 1 to 17,
Powertrain (2) field conversion, characterized in that, after said conversion, in the bottom dead center position of said piston (112'), said piston is entirely below air ports (128').