CN109281787B

CN109281787B - Large two-stroke compression ignition internal combustion engine with dual fuel system

Info

Publication number: CN109281787B
Application number: CN201811009563.1A
Authority: CN
Inventors: 约翰·卡尔托弗; 约恩·S·安德森; 波尔·岑克尔
Original assignee: MAN Diesel and Turbo Filial af MAN Diesel and Turbo SE
Current assignee: MAN Energy Solutions Filial af MAN Energy Solutions SE
Priority date: 2017-09-04
Filing date: 2018-08-31
Publication date: 2020-03-06
Anticipated expiration: 2038-08-31
Also published as: JP6650003B2; JP2019044774A; KR20190026620A; DK201770660A1; DK179683B1; KR102058380B1; CN109281787A

Abstract

The invention relates to a crosshead type large two-stroke turbocharging compression ignition multi-cylinder internal combustion engine (9). The engine (9) comprises a first fuel supply and injection system (52) for delivering a first type of fuel to the cylinders (1) of the engine, and comprises a hydraulically driven pump (43) and/or a pressure booster for pressurizing the first type of fuel; a second fuel supply and injection system (53) for delivering a second type of fuel to cylinders of the engine and comprising a hydraulically driven pump and/or supercharger (39) for pressurising the second type of fuel; and a hydraulic pumping station (22) comprising a plurality of mechanically driven hydraulic pumps (24, 25), the mechanically driven hydraulic pumps (24, 25) being driven by power output from the engine. The engine is configured to selectively operate using a first fuel or a second fuel. The hydraulic pumping station (22) is configured to: the first fuel supply and injection system (52) is supplied with hydraulic power when the engine is operating using a first fuel, and the hydraulic pumping station (22) is configured to supply hydraulic power to the second fuel supply and injection system (53) when the engine is operating using a second fuel.

Description

Large two-stroke compression ignition internal combustion engine with dual fuel system

Technical Field

The present disclosure relates to a large two-stroke compression-ignition internal combustion engine with a dual fuel system.

Background

Large two-stroke single-flow turbine supercharged compression-ignition crosshead internal combustion engines are commonly used as prime movers for propulsion systems of large ships or power plants. The absolute volume, weight and power output make them quite different from ordinary internal combustion engines and group large two-stroke turbocharged compression-ignition internal combustion engines for themselves.

Large two-stroke compression-ignition internal combustion engines are typically operated with liquid fuels such as, for example, fuel oil or heavy fuel oil. However, increased environmental concerns have led to a move towards the use of alternative fuels, such as natural gas, petroleum gas, methanol, ethanol, coal slurry, petroleum coke, and the like. The gas is typically stored in liquid form but is injected in gaseous form.

These alternative fuels have characteristics that are difficult or impossible to handle with conventional fuel pumps. Some fuels, such as coal slurries, are abrasive, some fuels, such as gasoline or ethanol, are of poor lubricating quality, and others, such as liquefied gas-cryogenic fuels, require extremely low temperatures.

In most applications, the engine is required to be able to run on conventional fuels such as marine diesel or heavy fuel oil, as well as on alternative and more environmentally friendly fuels such as liquefied gas or ethanol.

Thus, a dedicated fuel supply and injection system is required for each fuel type used. This need for two separate fuel supply and injection systems significantly increases the initial cost of building the engine, as well as increases the complexity and maintenance costs of the engine.

Accordingly, there is a need for an engine that can operate with two different types of fuels and that can overcome or at least reduce the additional cost and added complexity.

Disclosure of Invention

It is an object of the present invention to provide an engine which overcomes or at least reduces the above mentioned problems.

The foregoing and other objects are achieved by the features of the independent claims. Further forms of realization are apparent from the dependent claims, the description and the drawings.

According to a first aspect, there is provided a large two-stroke turbocharged compression ignition multi-cylinder internal combustion engine of the crosshead type, comprising:

a first fuel supply and injection system for delivering a first type of fuel to a cylinder of the engine, the first fuel supply and injection system comprising a hydraulically driven pump and/or a pressure intensifier (pressurizer) for pressurizing the first type of fuel,

a second fuel supply and injection system for delivering a second type of fuel to a cylinder of the engine, the second fuel supply and injection system comprising a hydraulically driven pump and/or a pressure intensifier for pressurising the second type of fuel, and

a hydraulic pumping station including a plurality of mechanically driven hydraulic pumps driven by power output from the engine,

the engine is configured to selectively operate using the first fuel or the second fuel, and

the hydraulic pumping station is configured to: the hydraulic pumping station is configured to supply hydraulic power to the first fuel supply and injection system when the engine is operating using the first fuel, and the hydraulic pumping station is configured to supply hydraulic power to the second fuel supply and injection system when the engine is operating using the second fuel.

By providing a single hydraulic pumping station that can flexibly power either of the two fuel supply systems, the provision of a dedicated pumping station for each fuel supply system can be avoided, thereby reducing cost and complexity.

According to a possible embodiment of the first aspect, the engine comprises a hydraulically driven exhaust valve actuation system which is operated both when the engine is operated with a first type of fuel and when the engine is operated with a second type of fuel, the hydraulic pumping station being configured to supply hydraulic power to the exhaust valve actuation system both when the engine is operated with the first type of fuel and when the engine is operated with the second type of fuel.

According to a possible embodiment of the first aspect, the selected set of the plurality of mechanically driven hydraulic pumps is dedicated to providing hydraulic power to the exhaust valve actuation system and the first fuel supply and injection system, and wherein one or more non-dedicated pumps of the plurality of mechanically driven hydraulic pumps selectively provide hydraulic power to the second fuel supply and injection system when the engine is operating with the second type of fuel.

According to a possible embodiment of the first aspect, the first electronic control valve on the outlet side of the non-dedicated pump is selectively connectable to a first conduit connecting the first electronic control valve to the first fuel supply and injection system and to the valve actuation system or to a second conduit connecting the first electronic control valve to the second fuel supply and injection system.

According to a possible embodiment of the first aspect, the first hydraulic pressure P1 required for the first fuel supply and injection system is lower than the second hydraulic pressure P2 required for the second fuel supply and injection system at least under certain operating conditions of the engine, and wherein the first conduit connects the first fuel supply and injection system with the hydraulic pumping station, and wherein the second conduit connects the second fuel supply and injection system with the hydraulic pumping station, the first conduit preferably also feeding the exhaust valve actuation system.

According to a possible embodiment of the first aspect, a hydraulic pressure booster pump is arranged in the second conduit for increasing the first pressure P1 delivered by the hydraulic pumping station to the second pressure P2, the hydraulic pressure booster pump being preferably driven by a hydraulic motor or an electric drive motor.

According to a possible embodiment of the first aspect, a hydraulic pressure reducing valve arrangement is arranged in the first conduit for reducing the second pressure P2 delivered by the hydraulic pumping station to the first pressure P1.

According to a possible embodiment of the first aspect, the selected set of the plurality of mechanically driven hydraulic pumps is dedicated to providing hydraulic power to the exhaust valve actuation system, the first fuel supply and injection system, and wherein the one or more variable displacement dedicated pumps of the plurality of mechanically driven hydraulic pumps provide hydraulic power to the second fuel supply and injection system when the engine is operating using the second type of fuel.

According to a possible embodiment of the first aspect, the one or more mechanically driven hydraulic pumps are variable displacement hydraulic pumps.

According to a possible embodiment of the first aspect, the engine comprises an electronic control unit configured to control the operation of the first fuel supply and injection system, the second fuel supply and injection system, the exhaust valve actuation system and the hydraulic pumping station, the electronic control unit being configured to:

the first fuel supply and injection system is ramped down,

the second fuel supply and injection system is ramped up (ramp up),

to divert a portion of the hydraulic power supplied by the hydraulic pumping station from the first fuel supply and injection system to the second fuel supply and injection system upon receiving a command to switch operation from the first type of fuel to the second type of fuel.

According to a possible embodiment of the first aspect, the electronic control unit is configured to ramp up the first fuel supply and injection system, ramp down the second fuel supply and injection system, and transfer a portion of the hydraulic power supplied by the hydraulic pumping station from the second fuel supply and injection system to the first fuel supply and injection system upon receiving a command to switch operation from the second type of fuel to the first type of fuel.

According to a possible embodiment of the first aspect, the hydraulic power supplied to the second fuel supply and injection system also supplies a hydraulic rotary motor driving a compressor compressing the second type of fuel in gaseous form.

According to a possible embodiment of the first aspect, the second fuel feeding and injection system comprises a hydraulically driven high-pressure pump comprising two or more pump units, each pump unit comprising a pump piston slidably arranged in a single pump cylinder and a hydraulically driven transmission piston slidably arranged in a single transmission cylinder, wherein the transmission piston is coupled to the pump piston for driving the pump piston.

According to a possible embodiment of the first aspect, the engine comprises at least one main control valve connected to the hydraulic pumping station and the fuel tank for controlling the flow of hydraulic fluid to and from the drive cylinders of the one or more pumping units, the source of high-pressure hydraulic fluid preferably being a source with a variable and controllable pressure level.

According to a possible embodiment of the first aspect, the engine comprises a heat exchanger or evaporator connected to the outlet of the hydraulically driven high-pressure pump.

According to a second aspect, there is provided an assembly comprising two engines according to the above embodiments, the engines sharing a single hydraulically driven high pressure pump and a heat exchanger or evaporator.

According to a possible embodiment of the second aspect, the hydraulic pumping station of each engine comprises at least one non-dedicated pump, wherein the inlet of the non-dedicated pump of the hydraulic pumping station of one of the engines is provided with a selector valve for selectively connecting an inlet associated with the fuel tank and the filtering system of the other engine or with an inlet associated with the fuel tank and the filtering system of the associated engine.

According to a possible embodiment of the second aspect, the assembly is configured to control the selector valve to connect the inlet of the non-dedicated pump provided with the selector valve to the fuel tank and the filtering system of another engine, when the other engine, associated with the non-dedicated pump, is connected to the second fuel supply and injection system.

According to a possible embodiment of the second aspect, the hydraulic pumping stations of the two engines each comprise at least one dedicated variable-displacement pump, the inlet of which is connected to the fuel tank and to the filtering system of one of the two engines in the assembly.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

In the following detailed part of the disclosure, the invention will be explained in more detail with reference to exemplary embodiments shown in the drawings, in which:

figure 1 is an elevation view of a large two-stroke diesel engine according to an exemplary embodiment,

figure 2 is a schematic view of the engine of figure 1 and its two fuel supply and injection systems, its exhaust valve actuation system and its hydraulic pumping station,

figure 3 is a more detailed schematic diagram of two fuel supply and injection systems and an exhaust valve actuation system,

figures 4 to 7 are schematic views of further embodiments of the engine of figure 1 and of its two fuel supply and injection systems, its exhaust valve actuation system and its hydraulic pumping station,

figures 8 to 10 are schematic views of another embodiment of the assembly of the two engines of figure 1 and their four fuel supply and injection systems, their exhaust valve actuation systems and their hydraulic pumping stations,

FIG. 11 is a graph showing a fuel supply flow rate during an operation of switching from a first type fuel to a second type fuel in the engine according to any of the embodiments, and

fig. 12 is a graph showing hydraulic power consumption of the respective fuel supply and injection systems during the operation of fig. 11 for switching from the first type of fuel to the second type of fuel.

Detailed Description

In the following detailed description, a fuel supply system for a large two-stroke low-speed turbocharged compression-ignition internal combustion engine 9 with crosshead will be described with reference to an exemplary embodiment. Fig. 1 shows a large slow turbocharged two-stroke diesel engine 9 with a steered wheel 7 and a crosshead. In this exemplary embodiment, the engine has six inline cylinders. Large slow turbo-charged two-stroke diesel engines typically have between four and fourteen in-line cylinders carried by a cylinder frame carried by the engine frame 6. The engine 9 may for example be used as a main engine in a ship or as a stationary engine for operating a generator in a power plant. The total output of the engine may be in the range of 1000kW to 110000kW, for example.

In this exemplary embodiment, the engine 9 is a two-stroke single-flow type compression ignition engine having a scavenging port at a lower region of the cylinder liner 1 and a central exhaust valve 4 at the top of the cylinder liner 1. The scavenging air is delivered from the scavenging air receiving portion 2 to the scavenging port of each cylinder 1. The piston in the cylinder liner 1 compresses the scavenging gas, injects high-pressure fuel such as gaseous fuel or liquid fuel through a fuel valve in the cylinder head, and then combusts and produces exhaust gas.

When the exhaust valve 4 is open, the exhaust gas flows through the exhaust duct associated with the cylinder concerned into the exhaust gas receiving portion 3 and onwards to the turbine of the turbocharger 5, from where it flows out through the exhaust duct and into the atmosphere. The turbine of the turbocharger 5 drives a compressor which is supplied with fresh air via an intake. The compressor delivers pressurized scavenging air to the scavenging air duct leading to the scavenging air receiving portion 2. The scavenging air in the scavenging air duct is passed through an intercooler for cooling the scavenging air.

Fig. 2 is a schematic illustration of the engine 9 and its

fuel injection system

52, 53, its exhaust valve actuation system 54 and its hydraulic pumping station 22. An electronic control unit 50 controls the operation of these systems. Although shown as a single unit, the electronic control unit 50 may have a distributed nature. The engine 9 and its system may be installed on a ship such as an LNG carrier or a tank ship.

The engine 9 is provided with a first fuel supply and injection system 52 for a first type of fuel, such as marine diesel or heavy fuel oil.

The engine 9 is also provided with a second fuel supply and injection system 53 for a second type of fuel, such as Liquefied Petroleum Gas (LPG), Liquefied Natural Gas (LNG), Liquefied Ethane Gas (LEG), etc. These liquefied gases are vaporized before injection and injected into the engine in gaseous form. Other examples of fuel types that may be used for the second fuel system are low flash point fuels such as ethanol or methanol.

The engine 9 is provided with a hydraulically driven and electronically controlled exhaust valve actuation system 54.

Hydraulic pumping station 22 supplies hydraulic power to various consumers of hydraulic power, including to first fuel supply and injection system 52, second fuel supply and injection system 53, and exhaust valve actuation system 54. The hydraulic pumping station 22 is provided with a plurality of mechanically driven

hydraulic pumps

24, 25. These

hydraulic pumps

24, 25 are driven by the power output from the engine, for example by a chain drive or a gear drive connecting the

hydraulic pumps

24, 25 to the engine crankshaft.

The hydraulic pumping station 22 is also provided with two hydraulically actuated pumps 26 which are driven by electric drive motors. These hydraulic start pumps 26 are used to provide hydraulic power and pressure for the start phase of the engine. These primer pumps 26 and other electrically driven pumps (not shown) may also be used to provide additional hydraulic power when the engine is running. The power to start the pump may be provided by a generator set associated with the engine or by another suitable source of electrical power such as mains electricity or a battery.

The engine 9 is provided with a lubricating oil system and a low-pressure hydraulic system. In an embodiment, the low pressure hydraulic system uses filtered lubrication oil as the hydraulic fluid.

The low-pressure pump 29 pressurizes the low-pressure hydraulic system. The hydraulic pumping station 22 provides hydraulic fluid from a low pressure hydraulic system via a conduit that includes a filter 28.

The engine 9 is configured to operate with either the first type of fuel or the second type of fuel. When the engine 9 is operated with the second type of fuel, a very small amount of the first type of fuel can be used as a pilot fuel (ignition liquid). However, such a very small amount of pilot fuel is not provided in the first fuel supply and injection system 52, but is provided by a dedicated pilot fuel delivery system, which is preferably integrated with the second fuel supply and injection system 53.

Fig. 11 is a graph showing fuel consumption of a first type of fuel represented by the unbroken lines and fuel consumption of a second type of fuel represented by the broken lines versus time. Thus, the graph illustrates a transition from operation with a first type of fuel to operation with a second type of fuel. At the beginning of the graph, the engine 9 is operated using the first type of fuel. At t1, the ecu 50 receives a command to change the operation from the first type of fuel to the second type of fuel, or at t1, the ecu 50 decides to change the operation from the first type of fuel to the second type of fuel. Thus, at t2, the control unit 50 ramps down the amount of the first type of fuel delivered and ramps up the amount of the second type of fuel delivered until the amount of the first type of fuel is zero and the amount of the second type of fuel is at the desired level.

At the same time, electronic control unit 50 starts controlling hydraulic pumping station 22 at t1 to decrease the amount of hydraulic power supplied to first fuel supply and injection system 52 and to increase the amount of hydraulic power supplied to second fuel supply and injection system 53. At t2, the hydraulic power distribution is consolidated.

As schematically shown in fig. 2, the engine 9 is provided with a hydraulically driven exhaust valve actuation system 54, which exhaust valve actuation system 54 operates both when the engine is operating on a first type of fuel and when the engine is operating on a second type of fuel. The hydraulic pumping station 22 is configured to supply hydraulic power to the exhaust valve actuation system 54 both when the engine 9 is operating using a first type of fuel and when the engine 9 is operating using a second type of fuel. A hydraulically driven exhaust valve actuation system 54 is controlled by electronic control unit 50.

In the embodiment of fig. 2, the hydraulic pumping station 22 includes three mechanically driven

hydraulic pumps

24, 25. The pump is driven by the power output from the engine 9. In this embodiment, the mechanically driven

hydraulic pumps

24, 25 are variable displacement pumps controlled by the electronic control unit 50, i.e. the displacement is controlled by the electronic control unit 50. A selected group of the plurality of mechanically-driven hydraulic pumps 24 (in the illustrated embodiment, the selected group includes two mechanically-driven hydraulic pumps 24) is dedicated to providing hydraulic power to exhaust valve actuation system 54, first fuel supply and injection system 52. One or more non-dedicated pumps 25 (in the illustrated embodiment, one non-dedicated pump 25 is shown) of the plurality of mechanically driven hydraulic pumps selectively provide hydraulic power to the second fuel supply and injection system 53 when the engine is operating with the second type of fuel.

The first electronic control valve 27 on the outlet side of the non-dedicated pump 25 is selectively connectable to the first piping 32 or the second piping 33. A first conduit 32 connects the first electronically controlled valve 27 to a first fuel supply and injection system 52, a valve actuation system 54, and a second conduit 33 connects the first electronically controlled valve 27 to a second fuel supply and injection system 53. The electronic control unit 50 commands the first electronic control valve 27. Thus, the electronic control unit 50 may selectively connect the non-dedicated pump 25 to either conduit 32 or conduit 33 to selectively provide hydraulic power from the non-dedicated pump 25 to the first fuel supply and injection system 52, the hydraulic vent valve actuation system 54, or to the second fuel supply and injection system 53.

The second fuel supply and injection system 53 comprises a heat exchanger or evaporator, indicated together with 71, connected to the outlet of a hydraulically driven high-pressure pump.

Hydraulic fluid is used to return to the fuel tank 61 from the first and second fuel supply and injection systems, the hydraulic vent valve actuation system. The low-pressure pump 29 supplies hydraulic fluid to the respective consumers of the engine 9 including the hydraulic pumping station 22 via a conduit including the filter 28.

Fig. 3 schematically shows in more detail a first fuel supply and injection system 52, a second fuel supply and injection system 53 and a hydraulic exhaust valve actuation system 54.

The second fuel supply system 53 comprises a fuel storage tank 8 storing a second type of fuel. If the fuel is a liquefied gas, it is stored in the fuel storage tank 8 under a low temperature condition. A feed line connects the outlet of the fuel or lube oil storage tank 8 to the inlet of the high pressure pump 40. The feed pump 10 assists in the delivery of fuel or lubricant from the storage tank 8 to the inlet of the pump 40.

The high pressure pump 40 pumps liquid fuel from the feed conduit 18 to the engine. The high-pressure pump 40 is provided with two or

more pump units

41, 42, 43 (in the present embodiment, 3 pump units are shown). Each

pump unit

41, 42, 43 comprises a pump piston 62 slidably arranged in a pump cylinder 61 and a hydraulically driven transmission piston 46 slidably arranged in a transmission cylinder 45, wherein the transmission piston 46 is coupled to the pump piston 62 for driving the pump piston 62.

The pump piston 62 and the pump cylinder 61 form a positive displacement pump. In an embodiment, the pump piston 62 and the pump cylinder 61 form a so-called cold end of a cryogenic pump unit having a pump chamber 63 for pumping liquefied gas.

The pump cylinder 61 is connected via a piston rod 49 to the transmission piston of the associated

pump unit

41, 42, 43. The drive piston 46 divides the interior of the drive cylinder 45 into a drive chamber 48 and a return chamber 47.

The drive cylinder 45 is connected to the hydraulic pumping station 22. The main control valve 19 controls the flow of high pressure hydraulic fluid to the transmission cylinder 45. The main control valve 19 is configured to selectively connect each transfer chamber 48 to either the conduit 33 or the fuel tank.

Each

pump unit

41, 42, 43 comprises a pump in the form of a linear positive displacement pump formed by a pump cylinder 61, the pump cylinder 61 and a pump piston 62 accommodated in the pump cylinder 61 forming a pump chamber 63. The pump chamber 63 is connected to the delivery duct 9 via a first one-way valve (not shown) which only allows fluid flow to the pressure chamber 63. The pump chamber 63 is connected to the supply conduit 18 via a second one-way valve (not shown) which only allows fluid to flow out of the pressure chamber 63.

If the second type of fuel is a cryogenic fuel, such as LNG or LPG, the high pressure pump 40 is a cryogenic pump. If the second type of fuel is a non-cryogenic fuel, such as ethanol, then the high-pressure pump 40 is a conventional linear positive displacement pump for pumping the non-cryogenic fluid.

The second fuel supply and injection system 53 comprises a liquefied gas storage tank 8 storing e.g. natural gas at cryogenic conditions (if a non-cryogenic fuel is used as the second type of fuel, a conventional storage tank 8 is used). The pressure in the LNG storage tank 8 is relatively low and is kept constant by allowing boil-off gas to escape from the storage tank, e.g. a low pressure gas injection engine for a boiler or an auxiliary engine such as a ship. The evaporation process also keeps the liquefied gas in the storage tank at a low temperature. The liquefied gas in the storage tank 8 may be of another type than natural gas, such as ethane or methane.

A feed line 9 connects the outlet of the LNG storage tank 8 to the inlet of the high pressure pump 40. The low pressure feed pump 10 assists in the transfer of liquefied gas from the LNG storage tank 8 to the inlet of the high pressure pump 40. Alternatively, the LNG storage tank 8 may be pressurized, so that the low pressure feed pump 10 may be omitted. A transfer conduit 13 connects an outlet of the high pressure pump 40 to an inlet of the high pressure evaporator 14 for conveying high pressure liquefied gas from the high pressure pump 40 to the high pressure evaporator 14. If the second type of fuel is not a liquefied gas, the high-pressure evaporator is replaced by a heat exchanger 14. The high-pressure pump 40 pumps the liquefied gas to the high-pressure evaporator 14 via the delivery line 13. The high pressure evaporator 14 receives the high pressure liquefied gas and evaporates the gas using a heat exchanger in the high pressure evaporator 14. The pressure evaporator 14 exchanges heat between a heat exchange medium, such as glycol, and liquefied gas, the heat exchange medium circulating in a circulation circuit 15. The circulation circuit 15 includes a circulation pump 16 and a heater 17. The high pressure boil-off gas leaves the high pressure evaporator 14 via an outlet of the high pressure evaporator 14 connected to a fuel supply conduit 18. The high-pressure pump 40 is designated together with the evaporator 14 as a pump evaporator unit (PVU) and as reference numeral 71.

A supply conduit 18 connects the outlet of the high-pressure evaporator 14 to the inlet of the fuel injection system of the second fuel supply and injection system 53. The conduit branches from the supply conduit 18 to each injector 64, the injectors 64 being configured to inject the second type of fuel into the cylinders 1.

The engine cylinder 1 is provided with a fuel valve 64 for injecting the second type of fuel and a fuel injection valve 23 for injecting the first type of fuel.

The first fuel injection supply system 52 is supplied with hydraulic power via the first conduit 32. The accumulator or compression chamber 67 ensures that a stable pressure is available for each consumer of hydraulic power, to which the distribution conduit 69 supplies pressure via each

control valve

11, 44, 55.

The first type of fuel is supplied from the storage tank 12 (supply tank) and delivered to the supercharger 39 by the electrically driven supply pump 16 via a feed line 73. The electrically driven feed pump 16 ensures that a pressure of about 4 bar can be maintained in the low pressure part of the fuel system.

Fuel injection of the first type of fuel is performed by an electronically controlled intensifier 39, one for each cylinder 1. The pressure booster 39 multiplies the pressure from the low pressure side (where the hydraulic fluid is applied) to the high pressure side (fuel side) by a fixed ratio.

The intensifier 39 is powered by pressurized hydraulic fluid. The hydraulic pumping station 22 delivers high pressure hydraulic fluid, typically several hundred bar. The return fluid is delivered from the cylinder to the fuel tank 61 via a conduit 65.

A compression chamber 67 is provided for each pair of cylinders 1 (in the case of an engine having an odd number of cylinders, one of which may be provided by a single compression chamber). A pipe 69 connects the compression chamber 67 to the proportional control valve 44, the on/off valve 55, and the proportional control valve 11.

Each cylinder 1 of the engine 9 is associated with an electronic control unit 50, which electronic control unit 50 receives the general synchronization and control signals and transmits the electronic control signals to the proportional control valve 44 through a signal line or lead 59. Each cylinder 1 may have one management control unit 50, or several cylinders 1 may be associated with the same electronic control unit 50.

The electronic control unit 50 calculates the timing, rate adjustment and amount of fuel injection according to the operating conditions of the engine 9. To this end, the electronic control unit 50 receives information about the rotational position of the crankshaft, the rotational speed of the crankshaft (which may be derived by the control unit 50 from the rotational position signal), the ambient temperature, the load, the temperature of various engine fluids. The electronic control unit 50 also adjusts the timing of fuel injection for reversing the engine. The movement of the spool in the proportional control valve 44 is controlled by the control unit 50.

In its rest position, the proportional control valve 44 connects the pressure chamber on the low-pressure side of the pressure booster 39 to the fuel tank. When the electronic control unit 50 sends a signal to start fuel injection to a given cylinder, one of the proportional control valves 44 is opened to a certain extent, and thereby connects the low-pressure side of the supercharger 39 to the compression chamber 67 via the pipe 69, so that hydraulic high pressure is applied from the hydraulic pumping station 22 to the low-pressure side of the supercharger 39.

The pressure on the low pressure side of the intensifier 39 is multiplied, typically to an injection pressure of between about 400 bar and 1500 bar. The feed conduit 51 delivers high pressure fuel from the intensifier 39 to the fuel injector 23, which fuel injector 23 injects a first type of fuel into the combustion chamber via its nozzle to atomize the first type of fuel.

The electronic control unit 50 also controls the actuation of the exhaust valve 4. The exhaust valve is opened and closed against the force of the air spring by a hydraulic valve actuator 21. The proportional control valve 11 selectively and proportionally controllably connects the hydraulic valve actuator 21 to the first conduit 35 via the conduit 77 and the compression chamber 67, or to the fuel tank 61 via the

conduits

78 and 65. The electronic control unit 50 controls the proportional control valve 11 via a signal line or lead 59. The electronic control unit 50 controls the timing of the lift of the exhaust valve 4 according to the crankshaft position and the engine operating conditions. In its rest position, the proportional control valve 11 connects the hydraulic vent valve actuator 21 to the fuel tank 61.

The electronic control unit 50 also controls an on/off valve 55, which controls the supply of pressurized cylinder lubricating oil to a cylinder lubricator 57. Based on the operating conditions and the position of the crankshaft, the control unit 50 determines when and how much cylinder lubricant is pumped into the cylinders 1. In its rest position, the on/off valve 55 connects the cylinder lubricator 57 to the fuel tank 61. When a given on/off valve 55 receives a signal from the control unit 50 to pump lubricating oil into a particular cylinder, the on/off valve 55 opens and thus connects the cylinder lubricator 57 to the compression chamber 67 via the conduit 69 and the cylinder lubricator will start pumping lubricating oil into the cylinder. The control unit 50 determines the amount of lubricating oil pumped into the cylinder via the length of time the on/off valve 55 is activated.

Thus, in an embodiment, the first conduit 32 additionally provides hydraulic power to the engine cylinder lubrication system. It is noted, though, that engine cylinder lubrication systems typically use a relatively small amount of hydraulic power compared to the amount of hydraulic power used by exhaust valve actuation systems and fuel injection systems.

Fig. 4 shows an embodiment which is substantially identical to the embodiment of fig. 2, except that the second conduit 33 is provided with a booster pump 34 for increasing the hydraulic pressure supplied to the second fuel supply and injection system 53. In an embodiment, first fuel supply and injection system 52 may require a lower hydraulic supply pressure P1 than hydraulic supply pressure P2 required by second fuel supply and injection system 53. In an embodiment, the desired supply pressure P1 for first fuel supply and injection system 52, exhaust valve actuation system 54 may follow engine load and be substantially equal to pressure P2 at maximum engine load. The booster pump 34 increases the output pressure of the non-dedicated pump 25 from pressure P1 to pressure P2. In this embodiment, the boost pump 34 is driven by a hydraulic motor 36. The hydraulic motor 36 is powered by hydraulic power from the second conduit 33.

Fig. 5 shows an embodiment that is substantially the same as the embodiment of fig. 4, except that the booster pump 34 is driven by an electric drive motor 38.

Fig. 6 shows an embodiment that is substantially identical to the embodiment of fig. 4, except that: all mechanically driven

hydraulic pumps

24, 25 are supplied with a high pressure P2 and a low pressure P1 by arranging a pressure reducing valve arrangement 31 in the first conduit 32 so that the first fuel supply and injection system 52, the hydraulic exhaust valve actuation system 52 receives a low pressure P1.

Fig. 7 shows an embodiment which is substantially identical to the embodiment of fig. 2, except that at least one mechanically driven variable displacement pump 20 is dedicated to feeding the second fuel feeding and injection system 53 via the second conduit 32. Thus, by adjusting the dedicated variable displacement pump 20 under the control of the electronic control unit 50, the pressure P2 supplied to the second fuel supply and injection system 53 may be independently adjusted.

Fig. 8 shows an assembly with two hydraulic pumping stations 22 and two engines 9, which uses a common PVU 71. Both hydraulic pumping stations 22 provide hydraulic power to a single common PVU 71. To avoid contamination of the hydraulic system of one engine by the hydraulic system of another engine, the return hydraulic fluid from the single common PVU71 is sent to the fuel tank 61 of one engine, and the dedicated variable displacement hydraulic pump 20 of the hydraulic pumping station 22 for both engines receives hydraulic fluid from the fuel tank 61 of one engine.

Fig. 9 shows an assembly of two engines 9 substantially identical to the assembly of fig. 8, except that the hydraulic pumping station is provided with a non-dedicated mechanically driven hydraulic pump 25. In order to avoid contamination of the hydraulic oil from one engine by the hydraulic oil of the other engine, the non-dedicated hydraulically driven pump 25 in the hydraulic pumping station 22 of one engine is provided with an electronically controlled selector valve 30 at its inlet so that the electronic control unit 50 can selectively supply the hydraulic fluid from the engine to which the non-dedicated mechanically driven hydraulic pump 25 belongs or from the other engine to the relevant non-dedicated mechanically driven hydraulic pump 25. Thus, when the non-dedicated mechanically driven hydraulic pump 25 is changed from feeding the first fuel feeding and injection system 52 to feeding the second fuel feeding and injection system 53, the electronic control unit 50 will command the first electronic control valves 27 of the two hydraulic pumping stations 22 and the electronic control selector valve 30 of the one hydraulic pumping station 22 to change position and vice versa.

Fig. 10 shows an embodiment that is substantially identical to the embodiment of fig. 7, except that the embodiment additionally includes a hydraulic rotary motor 70 that drives a compressor 72. The compressor 72 compresses the gaseous second type of fuel for the second fuel supply and injection system 53. The hydraulic power supplied to the second fuel supply and injection system 53 also powers a hydraulic rotary motor 70 that drives a compressor 72.

Fig. 11 shows the fuel supply flow F (l/s) versus time t(s) during a switch from 100% operation with a first type of fuel (shown by unbroken lines) to 100% operation with a second type of fuel (shown by broken lines) in an engine according to any one of the embodiments. At t1, operation with the first type of fuel is at ramp down, while operation with the second type of fuel is at ramp up. Ramping down operation with the first type of fuel and ramping up operation with the second type of fuel continues until T2, at T2 the engine runs 100% on the second type of fuel. Thus, at t2, the handover is completed.

Fig. 12 shows the hydraulic power consumption h (kw) of the respective fuel supply and injection systems during the switching of the operation of fig. 11 from the first type of fuel to the second type of fuel. The hydraulic power consumption of the first fuel system and the vent valve actuation system is shown by the unbroken lines and the hydraulic power consumption of the second fuel system is shown by the broken lines. At t1, the power consumption of the first fuel system and the exhaust valve actuation system begins to decrease until it reaches a plateau at t2, i.e., at the completion of the fuel switch. The remaining fuel consumption represents the fuel consumption of the exhaust valve actuation system, since the first fuel system will no longer use any hydraulic power. At t1, the power consumption of the second fuel system starts to increase and reaches a plateau at t2, i.e., at the completion of the shift.

The invention has been described herein in connection with various embodiments. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The electronic control units may be formed by a combination of separate electronic control units. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Reference signs used in the claims shall not be construed as limiting the scope.

Claims

1. A large two-stroke turbocharged compression-ignition multi-cylinder internal combustion engine (9) of the crosshead type, the engine (9) comprising:

a first fuel supply and injection system (52) for delivering a first type of fuel to a cylinder (1) of the engine, and

a second fuel supply and injection system (53) for delivering a second type of fuel to a cylinder of the engine,

wherein the first fuel supply and injection system comprises a hydraulically driven pump (39) and/or a pressure intensifier for pressurizing the first type of fuel,

said second fuel supply and injection system comprising a hydraulically driven pump and/or a pressure booster (43) for pressurizing said second type of fuel, and

a hydraulic pumping station (22) comprising a plurality of mechanically driven hydraulic pumps (24, 25), the mechanically driven hydraulic pumps (24, 25) being driven by a power output from the engine (9),

the hydraulic pumping station (22) is configured to: supplying hydraulic power to the first fuel supply and injection system (52) when the engine is operating using the first fuel, and the hydraulic pumping station (22) is configured to supply hydraulic power to the second fuel supply and injection system (53) when the engine is operating using the second fuel.

2. The engine (9) of claim 1 including a hydraulically driven exhaust valve actuation system (54) that operates both when the engine is operating with the first type of fuel and when the engine is operating with the second type of fuel, the hydraulic pumping station (22) being configured to supply hydraulic power to the exhaust valve actuation system (54) when the engine is operating with the first type of fuel and when the engine is operating with the second type of fuel.

3. The engine (9) of claim 2 wherein a selected set of the plurality of mechanically driven hydraulic pumps (24) is dedicated to providing hydraulic power to the exhaust valve actuation system (54) and the first fuel supply and injection system (52), and one or more non-dedicated pumps (25) of the plurality of mechanically driven hydraulic pumps selectively provide hydraulic power to the second fuel supply and injection system (53) when the engine is operating with the second type of fuel.

4. The engine (9) according to claim 3, wherein a first electronic control valve (27) on an outlet side of the non-dedicated pump (25) is selectively connectable to a first conduit (32) or a second conduit (33), the first conduit (32) connecting the first electronic control valve (27) to the first fuel supply and injection system (52) and the valve actuation system (54), and the second conduit (33) connecting the first electronic control valve (27) to the second fuel supply and injection system (53).

5. The engine (9) as claimed in any of claims 1 or 4, wherein a first hydraulic pressure P1 required for the first fuel supply and injection system (52) is lower than a second hydraulic pressure P2 required for the second fuel supply and injection system (53) at least under certain operating conditions of the engine, and the first conduit (32) connects the first fuel supply and injection system (52) with the hydraulic pumping station (22), and wherein the second conduit (33) connects the second fuel supply and injection system (53) with the hydraulic pumping station (22).

6. The engine (9) of claim 5, wherein the first conduit (32) also feeds the exhaust valve actuation system (54).

7. The engine (9) according to claim 5, wherein a hydraulic pressure booster pump (34) is arranged in the second conduit (33) for increasing the first pressure P1 delivered by the hydraulic pumping station to the second pressure P2.

8. The engine (9) of claim 7 wherein the hydraulic boost pump is driven by a hydraulic motor (35) or an electric drive motor (38).

9. The engine (9) according to claim 5, wherein a hydraulic pressure reducing valve mechanism (31) is arranged in the first conduit (32) for reducing the second pressure P2 delivered by the hydraulic pumping station (22) to the first pressure P1.

10. The engine (9) of claim 1 or 2, wherein a selected set of the plurality of mechanically driven hydraulic pumps (24) is dedicated to providing hydraulic power to the exhaust valve actuation system (54) and the first fuel supply and injection system (52), and wherein one or more variable displacement dedicated pumps (25) of the plurality of mechanically driven hydraulic pumps provide hydraulic power to the second fuel supply and injection system (53) when the engine is operating using the second type of fuel.

11. An engine (9) according to claim 1, wherein one or more of the mechanically driven hydraulic pumps (24, 25) are variable displacement hydraulic pumps.

12. The engine (9) of claim 1, comprising an electronic control unit (50) configured to control operation of the first fuel supply and injection system (52), the second fuel supply and injection system (53), the exhaust valve actuation system (54) and the hydraulic pumping station (22), the electronic control unit (50) being configured to:

ramping down the first fuel supply and injection system (52),

ramping up the second fuel supply and injection system (53), an

To divert a portion of the hydraulic power supplied by the hydraulic pumping station (22) from the first fuel supply and injection system (52) to the second fuel supply and injection system (53) upon receiving a command to switch operation from the first type of fuel to the second type of fuel.

13. The engine (9) according to claim 12, wherein the electronic control unit is configured to:

ramping up the first fuel supply and injection system (52),

ramping down the second fuel supply and injection system (53), an

To transfer a portion of the hydraulic power supplied by the hydraulic pumping station (22) from the second fuel supply and injection system (53) to the first fuel supply and injection system (54) upon receiving a command to switch operation from the second type of fuel to the first type of fuel.

14. The engine (9) according to claim 1, wherein the second fuel feeding and injection system (53) comprises a hydraulically driven high-pressure pump (40), the high-pressure pump (40) comprising two or more pump units (41, 42, 43), each pump unit (41, 42, 43) comprising a pump piston (62) slidably arranged in a single pump cylinder (61) and a hydraulically driven transmission piston (46) slidably arranged in a single transmission cylinder (45), wherein the transmission piston (46) is coupled to the pump piston (62) for driving the pump piston (62).

15. An engine (9) according to claim 14, further comprising at least one main control valve (19) connected to the hydraulic pumping station (22) and fuel tank for controlling the flow of hydraulic fluid to and from the drive cylinders (45) of one or more of the pump units (41, 42, 43).

16. The engine (9) of claim 15, the hydraulic pumping station (22) being a source with a variable and controllable pressure level.

17. An engine (9) according to claim 14 or 15, further comprising a heat exchanger (14) or an evaporator (14) connected to an outlet of the hydraulically driven high-pressure pump (40).

18. An assembly comprising two engines (9) according to claim 17 sharing a single hydraulically driven high pressure pump (40) and a heat exchanger (14) or evaporator (14).

19. Assembly according to claim 18, wherein the hydraulic pumping station (22) of each engine comprises at least one non-dedicated pump (25), wherein the inlet of the non-dedicated pump (25) of the hydraulic pumping station (22) of one of the engines is provided with a selector valve (30) for selectively connecting an inlet associated with the fuel tank and the filtering system of the other engine or with the fuel tank and the filtering system of the associated engine.

20. An assembly according to claim 19, configured to control said selector valve (30) to connect the inlet of the non-dedicated pump (25) provided with said selector valve (30) to the fuel tank and to the filtering system of said other engine, when said non-dedicated pump (25) is connected to said second fuel supply and injection system (53).