KR20230059758A - A large two-stroke uniflow scavenged gaseous fueled engine and method for controlling supply of liquid fuel - Google Patents

Abstract

The present invention relates to a large two-stroke uniflow scavenged gaseous fueled pre-mix engine and a method for controlling supply of liquid fuel. An engine has a plurality of mechanical design constraints and includes: a plurality of combustion chambers and a piston (10) reciprocating between a BDC and a TDC, which are provided in a cylinder liner (1); at least one gaseous fuel inflow valve (30); at least one liquid fuel valve (50) supplying, in a timed manner, liquid fuel to the combustion chambers to initiate ignition; and a controller (60) associated with the engine. Here, the controller (60) is configured to: control, for each combustion chamber, the timing and amount of gaseous fuel permitted into the combustion chamber through the at least one gaseous fuel inflow valve (30) during a stroke of the piston from the BDC to the TDC; monitor a combustion process for each cylinder (1) and detect when the combustion process causes one or more of the mechanical design constraints to be exceeded; and supply, in a timed manner, a first amount of liquid fuel so that a second amount is greater than the first amount, when the combustion process does not cause any predetermined mechanical design constraint to be exceeded. Therefore, the risk of occurrence of undesirable combustion phenomena can be overcome or at least reduced.

Description

Large two-stroke single-flow scavenging gaseous fuel engine and liquid fuel supply control method

The present invention relates to a large two-stroke gaseous fuel internal combustion engine, and more particularly, fuel flow from a valve during a piston stroke from Bottom Dead Center (BDC) to Top Dead Center (TDC). It relates to the operation of a large two-stroke single-flow scavenging internal combustion engine with crossheads on gaseous fuel.

Large two-stroke turbocharged single-flow scavenging internal combustion engines with crossheads are used, for example, for propulsion of large ocean-going vessels or as main power units for power plants. Not simply because of their size, these two-stroke diesel engines are constructed differently from other internal combustion engines. The weight of the exhaust valves of these engines is up to 400 kg, the diameter of the piston is up to 100 cm, and the maximum operating pressure in the combustion chamber is typically several hundred bar. The forces associated with these high pressure levels and piston sizes are enormous.

Large two-stroke turbocharged internal combustion engines operated on gaseous fuel introduced by fuel valves centrally located along the length of the cylinder liner or cylinder cover (i.e., the speed of the piston (BDC to TDC) starting well before the exhaust valves closed. ) engines that admit gaseous fuel during their upstroke) compress a mixture of gaseous fuel and scavenging air in the combustion chamber and use timed ignition means (e.g. liquid fuel injection) at or near TDC ) to ignite the compressed mixture.

This type of gas inlet uses a fuel valve (gas inlet valve) disposed in the cylinder liner or cylinder cover to inject the gaseous fuel when the compression pressure is relatively low, so that the piston is close to TDC or TDC has the advantage of being able to use much lower fuel injection pressures compared to large two-stroke turbocharged internal combustion engines that inject gaseous fuel when in the combustion chamber (i.e., when the compression pressure in the combustion chamber is at or near maximum). The latter type of engine requires a much higher fuel injection pressure than the already high maximum combustion pressure. Fuel systems capable of handling gaseous fuels at these extremely high pressures are expensive and complex due to the volatile nature of gaseous fuels and their behavior at these high pressures, including diffusion into and through steel components of the fuel system. do.

Thus, compared to an engine injecting gaseous fuel at high pressure when the piston is at or near TDC, the fuel supply system of an engine injecting gaseous fuel during the compression stroke is much cheaper.

However, when gaseous fuel is injected during the compression stroke, the piston compresses a mixture of gaseous fuel and scavenging air and consequently there is a risk of pre-ignition. Also, the combustion process is more difficult to control compared to engines that inject fuel at or near TDC. Apart from pre-ignition, the difficulties commonly posed are harsh combustion (too high rate of pressure increase during combustion) and/or maximum design pressure being exceeded.

JP2020200831 discloses a large premixed two-stroke turbocharged single-flow scavenging gas operated internal combustion engine, wherein the internal combustion engine has a plurality of combustion chambers, and at least one controller associated with the engine, the controller having a combustion chamber at the time of initiating combustion. is configured to determine an average compression air excess ratio and a bulk compression temperature of, and the controller is configured to perform the following:

- if the determined or measured average compressed air excess percentage is lower than a lower compressed air excess percentage threshold, performing at least one compressed air excess percentage increase measurement;

- if the determined or measured average compressed air excess percentage exceeds an upper compressed air excess percentage threshold, at least one compressed air excess percentage reduction measurement is performed;

- if the determined or measured bulk compression temperature is lower than a lower bulk compression temperature threshold, performing at least one bulk compression temperature increase measurement; and

- if the determined or measured bulk compression temperature is higher than the upper bulk compression temperature threshold, at least one bulk compression temperature reduction measurement is performed.

Premix engines require a time-limited ignition system because the compression ratio is selected so that combustion is not triggered by compression itself. Timed ignition systems are often based on injection (sometimes in conjunction with spark plugs) of liquid fuel (eg fuel oil (pilot oil)). The timing is typically at or near TDC, and is generally adjusted according to operating conditions. Thus, in one mode of operation this type of engine operates with incoming gaseous fuel as the main fuel (i.e. providing the main energy supplied to the engine) at a relatively low pressure during the stroke of the piston from BDC to TDC, whereas: The liquid fuel constitutes a relatively small amount of fuel that makes a relatively small contribution to the amount of energy supplied to the engine, where the purpose of the liquid fuel is timed ignition.

Accordingly, there is a need to improve the control over the condition of the combustion chamber in such large two-stroke turbocharged internal combustion engines in order to overcome or at least reduce the risk of occurrence of undesirable combustion phenomena indicated above.

A known method of reducing the risk of occurrence of the undesirable combustion phenomena indicated above is to increase the amount of liquid fuel injected. Generally, however, increased emissions are associated with the use of increased amounts of liquid fuel, and therefore it is generally desirable to minimize the amount of liquid fuel used. A known method for determining the amount of liquid fuel required to avoid the aforementioned undesirable combustion phenomena is a function based on the determined air-fuel ratio. However, accurately determining the air-fuel ratio is a difficult task in itself, and therefore, a safety margin is generally required to be used, and as a result, the amount of liquid fuel supply used is higher than necessary, resulting in more emissions than necessary.

It is an object of the present invention to provide an engine and method that overcomes or at least reduces the above problems.

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

According to a first aspect, there is provided a large two-stroke turbocharged single-flow scavenging internal combustion engine configured to use gaseous fuel as primary fuel in a gaseous mode of operation, wherein the engine has a number of mechanical design constraints, the engine comprising:

A plurality of combustion chambers each divided by a cylinder liner, a piston configured to reciprocate between BDC and TDC, and a cylinder cover;

scavenging ports arranged on the cylinder liner for introducing scavenging air into the combustion chamber;

an exhaust gas outlet disposed on the cylinder cover and controlled by an exhaust valve;

one or more gaseous fuel inlet valves arranged on the cylinder liner or cylinder cover configured to admit gaseous fuel during the stroke of the piston from BDC to TDC;

one or more liquid fuel valves configured to provide a timed supply of liquid fuel to the combustion chamber to initiate ignition;

At least one controller associated with the engine,

wherein the at least one controller is configured to control the timing and amount of gaseous fuel introduced into the combustion chamber during a stroke of the piston from BDC to TDC through the one or more gaseous fuel inlet valves individually for each combustion chamber; and ,

the at least one controller is configured to monitor the combustion process for each cylinder and detect when the combustion process causes the combustion process to exceed one or more of the mechanical design constraints; and

wherein the at least one controller is configured to timed supply a first quantity of liquid fuel when the combustion process does not exceed any predetermined mechanical design constraints;

wherein the at least one controller is configured to timed supply a second quantity of liquid fuel such that the second quantity is greater than the first quantity when the combustion process exceeds one or more predetermined mechanical design constraints. do.

Determining the need for increased amounts of liquid fuel based on exceeding mechanical design constraints provides a reliable and relatively uncomplicated solution for large two-stroke internal combustion engines to avoid undesirable combustion conditions. The information necessary for the controller to determine mechanical design constraints is already commonly available in these engines, so determining whether these mechanical design constraints are exceeded is a form of software used by the controller configured to process this information. It is relatively easy to implement with .

As a possible implementation of the first aspect, the engine is equipped with a timed ignition system so that combustion is not triggered by compression itself. The timed ignition system is preferably based on injection (sometimes in conjunction with a spark plug) of liquid fuel (eg fuel oil (pilot oil)). The timing is preferably at or near TDC and is controlled by a controller, preferably adjusted by the controller according to operating conditions.

In a possible implementation of the first aspect, the controller is configured to inject a first or second quantity of liquid fuel, preferably for each engine cycle, preferably at or near TDC.

In a possible implementation of the first aspect, the controller is configured to inject the first or second quantity using at least one pilot oil and/or a liquid fuel injection valve in the cylinder cover at or at an angle close to TDC. .

In a possible implementation of the first aspect, an angle for injecting the first or second quantity of liquid fuel is determined by the controller as a function of operating conditions of the engine.

The engine is a single-flow scavenging engine, that is, the scavenge air enters through arranged scavenging ports and the lower end of the cylinder liner and leaves the cylinder through an exhaust valve at the top of the engine, and in the cylinder liner The flow direction of the gas is generally always the same from the bottom of the cylinder liner to the top of the cylinder liner.

In a possible implementation of the first aspect, the gaseous fuel is one of methanol, LPG, LNG, ethane and ammonia.

In a possible implementation of the first aspect, the mechanical design constraint is a predetermined mechanical design constraint.

In a possible implementation of the first aspect, the mechanical design constraint is one or more of the following:

- combustion initiation defined by the liquid fuel supply timing;

- a predetermined maximum rate of increase in cylinder pressure during combustion,

- a given maximum cylinder pressure,

- engine operating point for a given nominal propeller curve, and

- Engine operating point for a given governor scavenging limiter curve.

In a possible implementation of the first aspect, the first quantity is a predetermined fixed quantity and the second quantity is a fixed predetermined quantity or a quantity that is a function of the extent to which mechanical design constraints are exceeded, preferably a proportional function. am.

In a possible implementation of the first aspect, the controller is configured to implement the highest of the second quantities indicated by any of the design constraints being exceeded.

In a possible implementation of the first aspect, the controller includes a governor that provides an index signal for the amount of fuel supplied to the associated cylinder, the governor being set or at a desired engine speed and the measured value. It is desirable to receive a signal representing the difference between engine speeds.

In a possible implementation of the first aspect, the controller is configured to adjust the quantity of gas supplied to the associated cylinder as a function of the quantity of liquid fuel supplied to the associated cylinder.

In a possible implementation of the first aspect, the engine includes a variable timing exhaust valve actuation system capable of individually controlling the exhaust valve timing of each combustion chamber.

In a possible implementation of the first aspect, the at least one controller is configured to individually determine and control timing of opening and closing of exhaust valves for each combustion chamber.

In a possible implementation of the first aspect, the controller receives a signal representing the cylinder pressure, is provided with or determines the angle at which the liquid fuel is supplied, and the controller initiates combustion based on these signals. start) precedes an ignition start defined by the supply timing of the liquid fuel, preferably the extent to which the combustion start precedes the ignition start defined by the liquid fuel supply timing. or configured to determine

and/or

The controller is configured to receive a signal representing the cylinder pressure, and based on the signal, to determine whether a predetermined maximum cylinder pressure increase rate during combustion has been exceeded, preferably the predetermined maximum cylinder pressure increase rate configured to determine the extent to which

and/or

The controller is configured to receive a signal indicative of the cylinder pressure, and the controller is configured to determine, based on the signal, whether the predetermined maximum cylinder pressure level has been exceeded, preferably wherein the predetermined maximum cylinder pressure increase rate is configured to determine the degree of excess;

and/or

The controller receives a signal representing the speed of the engine and a signal representing the fuel index, and the controller is configured to determine whether or not an engine operating point deviate from a nominal propeller curve based on these signals, , preferably configured to determine the degree of deviation of the engine operating point from the nominal propeller curve,

and/or

The controller receives a signal representing the scavenging pressure, and the controller determines whether the engine operating point deviates from the predetermined governor scavenge air limiter curve based on the signal. and preferably to determine a degree of deviation of the engine operating point from a predetermined governor scavenging limiter curve.

In a possible implementation of the first aspect, the controller is configured to control ignition timing by activating one or more liquid fuel valves, preferably at or near TDC.

In a possible implementation of the first aspect, the second quantity is equal to the first quantity increased by a predetermined amount or percentage or a previously applied second quantity increased by a predetermined amount or percentage.

In a possible implementation of the first aspect, the liquid fuel is a fuel oil.

In a possible implementation of the first aspect, the engine comprises a pressure sensor (preferably a pressure sensor arranged in a cylinder cover), the pressure sensor generating a signal indicative of the pressure in the combustion chamber.

According to a second aspect, a large two-stroke turbocharged single-flow scavenging internal combustion engine with multiple combustion chambers operating in a gaseous mode of operation, wherein the air-fuel mixture is present in the plurality of combustion chambers prior to ignition and the engine has a number of mechanical design constraints. A method is provided, wherein the method:

controlling the timing and quantity of gaseous fuel admitted to the combustion chambers through one or more gaseous fuel inlet valves individually for each combustion chamber during the stroke of the piston from BDC to TDC;

monitoring the combustion process for each cylinder to detect if the combustion process causes the exceeding of one or more of the mechanical design constraints;

providing a timed supply of a first quantity of liquid fuel if the combustion process does not result in the exceeding of any one of the predetermined mechanical design constraints; and

providing a timed supply of a second quantity of liquid fuel, wherein the second quantity is greater than the first quantity, if the combustion process results in exceeding one or more of the predetermined mechanical design constraints; includes

These and other aspects will be apparent from the examples described below.

According to the large two-stroke single-flow scavenging gas fuel engine and liquid fuel supply control method according to the present invention, there is an effect of overcoming or at least reducing the risk of occurrence of undesirable combustion phenomena.

In the following detailed description of the invention, aspects, embodiments and implementations will be described in more detail with reference to exemplary embodiments shown in the drawings, wherein:
1 is a front view of a large two-stroke diesel engine according to one embodiment;
2 is a side view of the large two-stroke engine of FIG. 1;
3 is a schematic diagram of a large two-stroke engine according to FIG. 1;
Fig. 4 is a cross-sectional view of the cylinder frame and cylinder liner of the engine of Fig. 1 with cylinder cover and exhaust valve, and pistons marked on both TDC and BDC; and
5 is a schematic diagram of a control system of the engine of FIG. 1;

In the following detailed description, an internal combustion engine will be described with reference to a large two-stroke low-speed turbocharged internal combustion crosshead engine in an exemplary embodiment. 1, 2 and 3 show an embodiment of a large slow speed turbocharged two-stroke diesel engine with a crankshaft (8) and a crosshead (9). 1 and 2 are a front view and a side view, respectively. Fig. 3 is a schematic diagram of the large slow speed turbocharged two-stroke diesel engine of Figs. 1 and 2 equipped with an intake and exhaust system; In this exemplary embodiment, the engine has four cylinders in series. Large slow speed turbocharged two-stroke internal combustion engines generally have four to fourteen cylinders arranged in a row carried by a frame (11). The engine is used, for example, as a main engine of a ship or as a stationary engine for operating a generator in a power plant. The total power of the engine may range from 1,000 to 110,000 kW, for example.

The engine of this exemplary embodiment is a two-stroke single-flow scavenging type engine having a scavenging port 18 in the lower region of the cylinder liner 1 and a central exhaust valve 4 at the top of the cylinder liner 1 . When the piston 10 is positioned below the scavenging port 18, the scavenging air is passed from the scavenging air receiver 2 through the scavenging ports 18 of the individual cylinder liner 1.

Gaseous fuel (e.g. methanol, LPG, LNG, ethane or ammonia) passes through the fuel valve 30 (gas inlet valve) when the piston moves upward (BDC to TDC) before the electronic controller 60 Under the control of the gas flows from the fuel valve (30). The gas is introduced at a relatively low pressure, less than 30 bar, preferably less than 25 bar, more preferably less than 20 bar. The fuel valves 30 are preferably evenly distributed around the circumference of the cylinder liner and located somewhere in the central region of the length of the cylinder liner 1 . Thus, the inflow of gaseous fuel occurs when the compression pressure is relatively low (ie much less than the compression pressure when the piston reaches TDC).

The piston 10 of the cylinder liner 1 compresses the gaseous fuel charge and scavenge air, compression takes place, and ignition is preferably arranged at or near TDC, in the cylinder cover 22. is triggered by injecting liquid fuel from the liquid fuel valves 50. Combustion follows and exhaust gases are produced.

When the exhaust valve 4 is opened, the exhaust gas flows to the exhaust gas receiver 3 through the exhaust duct connected to the cylinder 1, and the turbine 6 of the turbocharger 5 through the first exhaust conduit 19. ), the exhaust gas flows through the second exhaust conduit through the economizer 20 to the outlet 21 and into the atmosphere. Via the shaft the turbine (6) drives a compressor (7) to which fresh air is supplied through an air inlet (12). The compressor 7 delivers the compressed scavenging air to the scavenging air conduit 13 leading to the scavenging air receiver 2 . The scavenging air in the conduit 13 passes through the intercooler 14 for cooling the scavenging air.

The cooled scavenging air is produced when the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging air receiver 2 (i.e. when the engine is in a low load or part load condition). It passes through an auxiliary blower 16 driven by an electric motor 17 which pressurizes the flow. At higher engine loads, the turbocharger compressor (7) delivers fully compressed scavenging air and the auxiliary blower (16) is bypassed via a check valve (15).

One controller 60 (electronic control unit 60, which may consist of several interconnected electronic units) generally controls the operation of the engine, e.g. gaseous fuel injection (quantity and timing), liquid fuel Control over injection (quantity and timing) and opening and closing of the exhaust valve 4 (timing and extent of lift) is exceeded. Preferably, the engine includes a variable timing exhaust valve actuation system allowing individual control of exhaust valve timing for each combustion chamber. The controller 60 is connected to the fuel valve 30 via a signal line or wireless connection, detects the angle of the liquid fuel valves 50, the exhaust valve actuator and the crankshaft and generates a signal representing the position of the crankshaft. It is connected to an angular position sensor 75, and a pressure sensor 70, preferably connected to the cylinder cover 22 or alternatively to the cylinder liner 1 that generates a signal indicative of the pressure in the combustion chamber.

Figure 4 shows a cylinder liner 1 generally designated for large two-stroke crosshead engines. Depending on the size of the engine, the cylinder liner 1 can be made in different sizes with cylinder bores generally ranging from 250 mm to 1000 mm, with typical lengths ranging from 1000 mm to 4500 mm. there is.

In Fig. 4, the cylinder liner 1 is shown mounted on a cylinder frame 23, and a cylinder cover 22 is disposed on top of the cylinder liner 1 with an airtight interface therebetween. 4, although it is clear that the two positions bottom dead center (BDC) and top dead center (TDC) do not occur simultaneously but are separated by a 180 degree rotation of the crankshaft 8, the piston (10) is shown schematically with dotted lines at both of these locations. The cylinder liner 1 is provided with a plurality of cylinder lubrication holes 25 distributed in the circumferential direction, which supply cylinder lubricating oil when the piston 10 passes through the cylinder lubrication holes 25. Connected to the lubrication line, the following piston rings (not shown) distribute cylinder lubricating oil to the running surface of the cylinder liner 1 . A typical geometric compression ratio of the premix engine is 8 to 15.

The pilot oil valves 50 (typically one or more per cylinder) are mounted on the cylinder cover 22 and are connected to a liquid fuel source (not shown). The timing and quantity of the liquid fuel injection is controlled by the controller 60 . A prechamber (not shown) and a tip may be provided on the cover of the cylinder 22, and typically, a tip provided with a nozzle having one or more nozzle holes of the pilot oil valve 50 allows the pilot fluid to flow into the prechamber (pre-chamber). chambers) and are arranged to be sprayed. The pre-chamber plays an auxiliary role to achieve stable ignition. In one embodiment the pre-chamber is a double pre-chamber, ie two pre-chambers connected in series.

The fuel valves 30 are installed on the cylinder liner 1 (or cylinder cover 22), and the nozzle is located at substantially the same height as the inner surface of the cylinder liner 1 and the fuel valve 30 ) protrudes from the outer wall of the cylinder liner 1. Typically, each cylinder liner 1 is provided with one or two, but possibly three or four fuel valves 30, distributed circumferentially around the cylinder liner 1 (preferably uniformly distributed in the circumferential direction). The fuel valves 30 are disposed substantially centrally along the length of the cylinder liner 1 in one embodiment. The fuel valves are connected to a pressurized source of gaseous fuel 40 (eg methanol, LPG, LNG, ethane or ammonia) (i.e. when the fuel is delivered to the fuel valves 30 the fuel is gaseous). Since the gaseous fuel is introduced during the stroke of the piston 10 from BDC to TDC, the pressure of the gaseous fuel source must be higher than the pressure present in the cylinder liner 1, and a pressure of less than 20 bar is typically It is sufficient for gaseous fuel delivered to the fuel valve 30. The fuel valves 30 are connected to the controller 60 to determine the opening/closing timing of the fuel valve and the opening time of the fuel valve 30 . 4 schematically shows the gaseous fuel supply system comprising a source of pressurized gaseous fuel 40 connected to the inlet of each of the gaseous fuel valves 30 via a gaseous fuels supply conduit 41 .

The engine has many mechanical design constraints, such as:

The intended combustion start defined by the liquid fuel supply timing, and the actual combustion may not precede the intended combustion start, and if this happens anyway, the phenomenon is referred to as pre-ignition called,

A predetermined maximum rate of increase in cylinder pressure during combustion, if this rate is exceeded, the resulting phenomenon is also referred to as severe combustion;

A predetermined maximum cylinder pressure, if this pressure is exceeded, strain on engine components may exceed design criteria, resulting in increased wear or damage;

Engine operating point relative to a given nominal propeller curve, e.g. if the engine operating point is too far away from the given nominal propeller curve, a situation that may occur during acceleration (e.g. acceleration of the vessel on which the engine is installed). an increase in the rotational speed of the engine),

or when the vessel equipped with the engine is experiencing rough conditions or strong head wind, this phenomenon is also referred to as heavy running;

- engine operating point for a given governor scavenge air limiter curve, which may occur for example in tropical conditions, resulting in a lower than required air/fuel ratio; May increase risk of pre-ignition.

The nominal propeller curve can be obtained by the relation Relative Propeller Power = (Relative Engine Speed)^3.

The governor scavenge air limiter curve is a curve defining the maximum allowable fuel index (for gaseous fuels) allowed at a given scavenge pressure.

In an embodiment, heavy running is determined by the following function:

Heavy Operations = (Governor Index - Speed ^2)* Speed

The governor index is the relative torque request of the speed controller, which is converted into liquid fuel and gas quantities. The speed used in the equation is the relative engine speed (i.e., the actual engine speed divided by the maximum engine speed, where the maximum engine speed equals the engine speed at max continuous rating for the nominal propeller curve).

In one embodiment, the controller 60 is configured to determine, as a function of the number of heavy runs, preferably as a proportional function.

The mechanical design constraint is a predetermined mechanical design constraint. The mechanical design constraints are determined during design and development of the engine and may be derived from calculations, computer simulations and/or testing (testing of the engine on a testbed).

FIG. 5 shows a schematic diagram of the control system for the engine of FIG. 1 and also illustrates how the controller 60 controls the fuel supply to individual cylinders 1 .

The controller 60 includes a governor that provides a fuel index for the quantity of fuel supplied to the associated cylinder. The governor receives a signal representing the difference between the set or desired engine speed (received from an external signal and controlled by the engine operator) and the measured engine speed derived from the signal of the angle sensor 75.

The controller 60 is individually configured for each cylinder to monitor the combustion process and sense when the combustion process causes one or more of the mechanical design constraints to be exceeded.

The controller 60 is configured to timed supply a first quantity of liquid fuel when the combustion process does not exceed any predetermined mechanical design constraints, wherein the combustion process exceeds one or more predetermined mechanical design constraints. and configured to provide a timed supply of the second quantity of liquid fuel when exceeded. The second quantity is greater than the first quantity.

Timed supply of the first quantity and the second quantity of liquid fuel is such that, in the engine, the (mechanical) compression ratio is the timed ignition system required so that combustion is not triggered by the compression itself. system) (i.e. the engine runs according to the Otto process, not the diesel process). The timed ignition system uses injection of liquid fuel (e.g. fuel oil (pilot oil)), sometimes combined with the use of a spark from a spark plug (not shown). The timing is determined by the controller 60, preferably at or near TDC, and preferably adjusted by the controller according to the operating conditions.

The first quantity may be any fixed quantity, but in one embodiment, the first quantity may also be adjusted by the controller 60 as a function of the operating conditions.

The second quantity is a quantity that is a function of the degree to which a fixed predetermined quantity or mechanical design constraint is exceeded (eg, a proportional function).

The controller 60 is configured to implement the highest of the second quantities indicated by any of the design constraints that are exceeded and issue a liquid fuel index. The control may be configured to maintain the second quantity for a given period of time, or alternatively, to maintain the second quantity until the control determines that no mechanical constraint has been exceeded. If the controller determines that a mechanical design constraint has been exceeded, but does not determine the extent to which it is exceeded, the controller issues an ignition fuel index in which the second quantity is a predetermined fixed quantity, which of course is always greater than the first quantity. or increase If the controller determines the extent to which the design constraint is exceeded, the controller calculates a quantity for the second quantity as a function of the extent to which the mechanical design constraint is exceeded, the second quantity still exceeding the first quantity. greater than or an increase in said first quantity.

The controller 60 receives the general fuel index and subtracts the liquid fuel index from it, as indicated by the summation point, the combined fuel energy of gaseous fuel and liquid fuel supplied to the relevant cylinder. and adjust the quantity of gas supplied to the associated cylinder as a function of the quantity of liquid fuel supplied to the associated cylinder to ensure that Δt matches the fuel energy/torque value supplied to the cylinder.

The controller 60 receives a signal representing the cylinder pressure from the pressure sensor 70, the controller 60 itself determines the angle at which the liquid fuel is supplied, and the controller 60 controls these signals. Based on, determine whether the start of combustion precedes the start of ignition defined by the supply timing of the liquid fuel, preferably the start of combustion precedes the start of ignition defined by the supply timing of the liquid fuel. configured to determine the degree of precedence.

The controller 60 receives a signal representing the cylinder pressure from the pressure sensor 70, and the controller 60 determines whether a predetermined maximum cylinder pressure increase rate during combustion has been exceeded based on the signal. and preferably configured to determine the extent to which the predetermined maximum cylinder pressure increase rate has been exceeded.

The controller 60 is configured to receive a signal indicative of the cylinder pressure from the pressure sensor 70 and, based on this signal, determine whether the predetermined maximum cylinder pressure level has been exceeded. It is configured to determine the extent to which a predetermined maximum cylinder pressure level has been exceeded.

The controller 60 receives a signal representing the engine speed from the angle sensor 75 and is notified of the fuel index, and the controller 60 determines the engine operating point from the nominal propeller curve based on these signals. configured to determine whether to deviate or not. The controller 60 is preferably configured to determine the extent to which the engine operating point deviates from the nominal propeller.

The controller 60 receives a signal indicative of the scavenge air pressure, for example, from a sensor (not shown) arranged in a scavenge air receiver 2 that generates a signal indicative of the scavenge air pressure; , the controller 60 is configured to determine, based on this signal, whether the engine operating point deviates from a predetermined governor scavenging limiter curve, preferably the engine operating point deviates from the predetermined governor scavenging limiter curve. configured to determine the degree.

The controller 60 is configured to control ignition timing by activation of one or more liquid fuel valves 50 . The onset of intended ignition is generally at or near TDC and is regulated by the controller 60 depending on operating conditions.

In one embodiment, the second quantity is an increase of the first quantity, or an increase of a previously applied second quantity.

In one embodiment the liquid fuel is fuel oil.

The airframe operating mode may be one of several operating modes of the engine. In the gaseous fuel mode of operation the engine operates on gaseous fuel entering the main fuel (i.e. providing most of the energy supplied to the engine) at a relatively low pressure during the stroke of the piston from BDC to TDC, whereas , the liquid fuel constitutes a relatively small amount of fuel that makes a relatively small contribution to the amount of energy supplied to the engine, and the purpose of the liquid fuel is timed ignition.

In one embodiment, the engine is a dual fuel engine, i.e. the engine has a mode of operation on liquid fuel only.

In one embodiment, the controller 60 is configured to inject the first or second quantity of liquid fuel, preferably at or near TDC, preferably for each engine cycle.

In one embodiment, the controller 60 operates one or more pilot oil valves 50 of a pilot oil system of a dual fuel engine and/or liquid fuel injection valves of a liquid fuel system at or near TDC at or near TDC. and injecting the first or second quantity of liquid fuel using

In one embodiment, the angle for injecting the first or second quantity of liquid fuel is determined by the controller 60 as a function of operating conditions of the engine.

Various aspects and implementations have been described in connection with various embodiments herein. However, other modifications to the disclosed embodiments in practicing the claimed subject matter may be understood and effected by those skilled in the art through a study of the drawings, disclosure, and appended claims. In this claim, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor, controller or other device may perform the functions of several items recited in the claims. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of measures cannot be used to advantage.

Reference signs used in the claims should not be construed as limiting the scope.

Claims (14)

A large two-stroke turbocharged single-flow scavenging internal combustion engine configured to use gaseous fuel as primary fuel in a gaseous operating mode, the engine having a number of mechanical design constraints, the engine comprising:
A plurality of combustion chambers each divided into a cylinder liner 1, a piston 10 configured to reciprocate between BDC and TDC, and a cylinder cover 22,
scavenging ports (18) arranged on the cylinder liner (1) for introducing scavenging air into the combustion chamber;
an exhaust gas outlet disposed on the cylinder cover (22) and controlled by an exhaust valve (4);
one or more gaseous fuel inlet valves (30) arranged on the cylinder liner (1) or cylinder cover (22) configured to introduce gaseous fuel during the stroke of the piston (10) from BDC to TDC;
one or more liquid fuel valves (50) configured to provide a timed supply of liquid fuel to the combustion chamber to initiate ignition;
As including a controller 60 associated with the engine,
wherein the controller 60 controls the timing and amount of gaseous fuel introduced into the combustion chamber during a stroke of the piston from BDC to TDC through the one or more gaseous fuel inlet valves 30 individually for each combustion chamber. constituted,
the controller (60) is configured to monitor the combustion process for each cylinder (1) and detect when the combustion process causes one or more of the mechanical design constraints to be exceeded; and
wherein the controller (60) is configured to timed supply a first quantity of liquid fuel if the combustion process does not cause any predetermined mechanical design constraints to be exceeded;
wherein the controller (60) is configured to timed supply a second quantity of liquid fuel when the combustion process exceeds one or more predetermined mechanical design constraints, wherein the second quantity is greater than the first quantity. Large, two-stroke turbocharged single-flow scavenging internal combustion engines, which are many.
The engine of claim 1 , wherein the mechanical design constraint is one or more of the following conditions:
- combustion initiation defined by the liquid fuel supply timing;
- a predetermined maximum rate of increase in cylinder pressure during combustion,
- a given maximum cylinder pressure,
- engine operating point for a given nominal propeller curve, and
- Engine operating point for a given governor scavenge air limiter curve.
2. The engine according to claim 1, wherein the first quantity is a predetermined fixed quantity and the second quantity is a quantity that is a function of the degree to which a predetermined fixed quantity or mechanical design constraint is exceeded, preferably a proportional function.
2. The engine of claim 1, wherein the controller (60) is configured to implement the highest of the second quantities indicated by any exceeded design constraints.
2. The method of claim 1, wherein the controller (60) is a governor providing an index signal for the quantity of fuel supplied to the cylinder concerned, wherein the governor is preferably set or or an engine that receives a signal indicative of a difference between a desired engine speed and a measured engine speed.
2. The engine of claim 1, wherein the controller (60) is configured to adjust the quantity of gas supplied to the cylinder concerned as a function of the quantity of liquid fuel supplied to the cylinder concerned.
The engine of claim 1 including a variable timing exhaust valve actuation system capable of individually controlling exhaust valve timing for each combustion chamber.
8. An engine according to claim 7, wherein said at least one controller (60) is configured to individually determine and control timing of opening and closing of said exhaust valve (4) for each combustion chamber.
According to claim 2,
The controller 60 receives a signal indicating the cylinder pressure, receives or determines the angle at which the liquid fuel is supplied, and the controller 60 determines the combustion start based on these signals. configured to determine whether the start of combustion precedes an ignition start defined by the supply timing of the fuel, and preferably configured to determine the degree to which the start of combustion precedes the start of ignition defined by the supply timing of the liquid fuel. or
and/or
The controller 60 is configured to receive a signal representing the cylinder pressure, and based on the signal, the controller 60 determines whether or not a predetermined maximum cylinder pressure increase rate during combustion has been exceeded. configured to determine the extent to which a predetermined maximum cylinder pressure increase rate has been exceeded;
and/or
The controller 60 is configured to receive a signal indicative of the cylinder pressure, and based on the signal, the controller 60 determines whether the predetermined maximum cylinder pressure level has been exceeded, preferably the predetermined cylinder pressure level is exceeded. Is configured to determine the degree to which the maximum cylinder pressure increase rate of is exceeded,
and/or
The controller 60 receives a signal representing the speed of the engine and a signal representing the fuel index, and the controller 60 determines the departure of the engine operating point from the nominal propeller curve based on these signals. Is configured to determine whether, preferably configured to determine the degree of deviation of the engine operating point from the nominal propeller curve,
and/or
The controller 60 receives a signal representing the scavenging pressure, and based on the signal, the controller 60 determines that the engine operating point is determined by the predetermined governor scavenge air limiter curve. and preferably configured to determine a degree of deviation of the engine operating point from a predetermined governor scavenging limiter curve.
2. An engine according to claim 1, wherein the controller (60) is configured to control ignition timing by activation of one or more liquid fuel valves (50), preferably located near TDC.
2. The engine of claim 1 wherein the second quantity is an increase of the first quantity or a previously applied increase of the second quantity.
2. An engine according to claim 1, wherein the liquid fuel is a liquid fuel, wherein the liquid fuel is preferably fuel oil.
2. The engine according to claim 1, wherein the engine comprises a pressure sensor (70), preferably a pressure sensor (70) disposed in the cylinder cover (22), the pressure sensor generating a signal indicative of the pressure in the combustion chamber. the engine that will be.
A method of operating a large two-stroke turbocharged single-flow scavenging internal combustion engine with multiple combustion chambers in gaseous mode of operation, wherein an air-fuel mixture is present in multiple combustion chambers prior to ignition and the engine has a number of mechanical design constraints, comprising: Way:
controlling the timing and quantity of gaseous fuel admitted to said combustion chambers through one or more gaseous fuel inlet valves (30) individually for each combustion chamber during the stroke of the piston from BDC to TDC;
monitoring the combustion process for each cylinder (1) to detect if the combustion process causes the exceeding of one or more of the mechanical design constraints;
providing a timed supply of a first quantity of liquid fuel if the combustion process does not result in the exceeding of any one of the predetermined mechanical design constraints; and
and providing a timed supply of a second quantity of liquid fuel if the combustion process results in an excess of one or more of the predetermined mechanical design constraints, wherein the second quantity is greater than the first quantity. how this is a bigger one.

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