DK181977B1

DK181977B1 - Internal combustion engine

Info

Publication number: DK181977B1
Application number: DKPA202330365A
Authority: DK
Inventors: Cronberg Anders; Jensen Emil; Hansen Kristoffer; Schierup Jakob; Jensen Kim
Original assignee: Man Energy Solutions Filial Af Man Energy Solutions Se Tyskland
Priority date: 2023-11-30
Filing date: 2023-11-30
Publication date: 2025-04-30
Also published as: DK202330365A1; KR20250083177A; KR102894147B1; CN120062015A; JP2025088777A; JP7775428B2

Abstract

The present invention relates to an internal combustion engine for propulsion of a vessel, the internal combustion engine having at least one cylinder, and comprising a fuel supply system comprising a first cylinder fuel supply channel comprising a first primary valve and a first secondary valve arranged upstream of the first primary valve, and a second cylinder fuel supply channel comprising a second primary valve and a second secondary valve arranged upstream of the second primary valve, wherein a first pressure sensor providing a first pressure signal is arranged between the first primary valve and the first secondary valve, and a second pressure sensor providing a second pressure signal is arranged between the second primary valve and the second secondary valve, and wherein the internal combustion engine further comprises a comparison unit comparing the first pressure signal with the second pressure signal for detecting discrepancies between the first pressure signal and the second pressure signal. The invention also relates to a leakage detection method for detection of a leakage in a valve in a fuel supply system, as well as a computer program product.

Description

DK 181977 B1 1

INTERNAL COMBUSTION ENGINE

Description

The present invention relates to an internal combustion engine for propulsion of a vessel, the internal combustion engine having at least one cylinder. The invention also relates to a leakage detection method for detection of a leakage in a valve in a fuel supply system, as well as a computer program product.

In designing vessels, e.g. container ships and tankers, the main focus is safety on board and prevention of environmental damage, while operating in a cost-efficient way. To operate in a safe and cost-efficient way, it is important to detect any malfunction of engine parts before the engine parts become so defect that replacement is needed and before the malfunction affects other engine parts.

A small leakage in the fluid channels, valves, etc., is difficult to detect but important because while the leakage is small, the damage is also very small and therefore only requires minor repair or displacement of only e.g. the leaking valve and not also related parts. However, if the leakage is not detected while being small, the repair becomes much more extensive and expensive, and the vessel may even be prevented from operating while the repairs are made.

An internal combustion engine for propulsion of a vessel is shown in DK 201970373.

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved internal combustion engine capable of detecting, in a simple manner, any leakage of the valves in the fuel supply system in order to avoid extensive damage and potential safety hazard while still being cost-efficient.

The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by an internal combustion engine for propulsion of a vessel, the internal combustion engine having at least one cylinder and comprising:

DK 181977 B1 2 - a fuel supply system comprising: - a first cylinder fuel supply channel comprising a first primary valve and a first secondary valve arranged upstream of the first primary valve, and - a second cylinder fuel supply channel comprising a second primary valve and a second secondary valve arranged upstream of the second primary valve, wherein a first pressure sensor providing a first pressure signal is arranged between the first primary valve and the first secondary valve, and a second pressure sensor providing a second pressure signal is arranged between the second primary valve and the second secondary valve, and wherein the internal combustion engine further comprises a comparison unit comparing the first pressure signal with the second pressure signal for detecting discrepancies between the first pressure signal and the second pressure signal.

Also, the at least one cylinder may be a first cylinder, and the internal combustion engine may further comprise a second cylinder.

In addition, the first cylinder fuel supply channel supplies fuel to one of the first and second cylinders, and the second cylinder fuel supply channel supplies fuel to one of the first and second cylinders.

In another internal combustion engine for propulsion of a vessel, the internal combustion engine may have at least a first cylinder and a second cylinder, and may comprise: - a fuel supply system comprising: - a first cylinder fuel supply channel for supplying fuel to one of the first and second cylinders comprising a first primary valve and a first secondary valve arranged upstream of the first primary valve, and - a second cylinder fuel supply channel for supplying fuel to one of the first and second cylinders comprising a second primary valve and a second secondary valve arranged upstream of the second primary valve, wherein a first pressure sensor providing a first pressure signal is arranged between the first primary valve and the first secondary valve, and a second pressure sensor providing a second pressure signal is arranged between the second primary valve and the second secondary valve, and

DK 181977 B1 3 wherein the internal combustion engine further comprises a comparison unit comparing the first pressure signal with the second pressure signal for detecting discrepancies between the first pressure signal and the second pressure signal.

When an internal combustion engine runs at low load and/or at low pressure, the pressure in the fuel supply system does not build up to the same extent as when the engine runs at high load or at high pressure, such as 300 bar, when the valve is closed. Thus, more conventional methods of leak detection do not work sufficiently efficiently. However, by measuring and comparing the pressure or a representation thereof between the primary valve and the secondary valve on both the first cylinder fuel supply channel and the second cylinder fuel supply channel, a small leakage or malfunction can be detected as the surounding factors, such as low pressure and low load, equally affect the pressures in the first cylinder fuel supply channel and the second cylinder fuel supply channel, respectively, so that the pressure build-up does not have to be so high in order to also detect small leakages.

By measuring and comparing the pressure or a representation thereof between the primary valve and the secondary valve on both the first cylinder fuel supply channel and the second cylinder fuel supply channel, a leakage or malfunction can be detected while still being very small as the pressure signals can be compared, so even if the pressure signals vary, the correlation between them will be significantly stable, even though the supply pressure varies or other factors around the fuel supply system vary.

In that way, an improved internal combustion engine capable of detecting, in a simple manner, any leakage or malfunction of the valves in the fuel supply system is obtained, and by such detection extensive damage and safety hazard can be avoided, which means that the internal combustion engine is more cost-efficient as repair or replacement of the leaking or malfunctioning valve can be performed before major damage occurs.

In the known internal combustion engines, leak detection of the valves in the fuel supply channel supplying fuel to a cylinder is performed by way of several tests, such as a volume test, a drop test, a curve fit test, a variation test and a max pressure test, to be able to detect any leakage or malfunction at an early stage.

DK 181977 B1 4

Especially the curve fit test has proved to be inadequate for engines running at low pressure and at low load. The present invention only requires one test.

Also, the first cylinder fuel supply channel may be in fluid connection with the first cylinder, and the second cylinder fuel supply channel may be in fluid connection with the first cylinder or the second cylinder.

Moreover, the first cylinder fuel supply channel may be in fluid connection with the first cylinder for injection of fuel into the first cylinder, and the second cylinder fuel supply channel may be in fluid connection with the first cylinder for injection of fuel into the first cylinder, or the second cylinder fuel supply channel may be in fluid connection with the second cylinder for injection of fuel into the second cylinder.

Further, the fuel supply system may comprise a main supply channel fluidly connected to the first cylinder fuel supply channel and the second cylinder fuel supply channel.

In addition, the main supply channel may be arranged upstream of the first cylinder fuel supply channel and the second cylinder fuel supply channel.

Furthermore, the fuel supply system may comprise a pump, and the main supply channel may be fluidly connected to the pump for feeding fuel to both the first cylinder fuel supply channel and the second cylinder fuel supply channel.

In addition, the fuel supply system may comprise a pressure control valve, and the main supply channel may be fluidly connected to the pressure control valve for controlling fuel to both the first cylinder fuel supply channel and the second cylinder fuel supply channel.

Also, the first pressure sensor may measure a real-time and/or continuous first pressure signal, and the second pressure sensor may measure a real-time and/or continuous second pressure signal.

Moreover, the fuel may be propane, butane, methanol, methane, ethanol, ethene, ethane, ammoniac, propylene, butylene, isobutane, n-butane, hydrogen, kerosene, nitromethane, liquefied petroleum gas, bioethanol or biodiesel.

DK 181977 B1

Furthermore, the fuel may be the only fuel supplied to the at least one cylinder.

In addition, the fuel may be a secondary fuel, and a primary fuel may be diesel, gasoline or petroleum. 5

Moreover, the primary fuel may have a sulphur content of at least 0.05%.

Further, the fuel may be liquid or gas.

Also, the primary valve may have an opening time period that is shorter than an opening time period of the secondary valve.

Moreover, the secondary valve may open before the primary valve opens.

By way of the measuring and comparing of the present invention, a leak in or malfunction of especially the secondary valve can be monitored and detected, which is very difficult with known systems where the curve fit test is performed.

When using the curve fit test, the measured pressure is usually compared to a reference curve; however, external factors such as running at low load or at low pressure will then affect the result so that the interval in which the measured pressure differs from the reference curve has to be very broad in order to also fit engine operation at low load and at low pressure. When the interval needs to be broad so that the engine is not stopped unintentionally, small leakages are not detected. A leakage in the secondary valve, also called a window valve, may be a potential safety hazard, and therefore it is important to detect such leakage at an early stage.

In addition, the secondary valve may open while the primary valve is closed.

Further, the secondary valve may close while the primary valve is closed.

Also, the primary valve may open and/or close while the secondary valve is open.

Moreover, the first pressure signal may form a first pattern, the second pressure signal may form a second pattern, and the comparison unit may compare the first pattern with the second pattern in order to detect a correlation and verify whether the correlation is within a predetermined interval.

DK 181977 B1 6 “Correlation” means any statistical relationship, e.g. statistical variance, between two set of pressure signal data, i.e. any type of association, referring to the degree to which a pair of variables are linearly related.

Further, the comparison unit may be a central processing unit (CPU), a control unit, an integrated circuit, such as a microchip or a chip, a comparative unit, or a hardware- or software-based comparator.

Also, the comparison unit may comprise pattern recognition software.

Moreover, the internal combustion engine may also comprise a third cylinder and a fourth cylinder, each being fed fuel from two fuel supply channels that each has a pressure sensor, a secondary valve and a primary valve.

In addition, the internal combustion engine may also comprise at least six cylinders.

Further, the first pressure signal may have a predefined number of data points in a predefined time period.

In addition, the second pressure signal may have a predefined number of data points in the predefined time period.

Furthermore, the predefined time period may be from one operation position of one of the valves until the same operation position occurs again.

Also, the predefined time period may be from the closing of the secondary valve until the next closing of the secondary valve.

Moreover, the combustion engine system may further comprise a turbocharger arranged downstream of the internal combustion engine.

Further, the turbocharger may comprise a turbine and a compressor.

In addition, the invention relates to a leakage or malfunction detection method for detection of a leakage in or malfunction of a valve in a fuel supply system for

DK 181977 B1 7 supplying fuel to at least one cylinder of an internal combustion engine, comprising: - measuring a first pressure signal in a first time period by a first pressure sensor between a first primary valve and a first secondary valve on a first cylinder fuel supply channel of the fuel supply system, - measuring a second pressure signal in the first time period or a second time period by a second pressure sensor between a second primary valve and a second secondary valve on a second cylinder fuel supply channel of the fuel supply system, and - comparing the first pressure signal with the second pressure signal in order to detect a leakage in or malfunction of one of the valves.

Further, the invention relates to a computer program product comprising a computer-readable medium holding computer program code means, and, when loaded, the computer program product will make a computer execute the leakage or malfunction detection method.

Furthermore, said internal combustion engine may be a large two-stroke internal combustion engine.

In addition, the internal combustion engine may be a large turbocharged two- stroke internal combustion engine of the crosshead type.

Further, the internal combustion engine may be a two-stroke or a four-stroke internal combustion engine.

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:

Fig. 1 shows a schematic diagram of a fuel supply system of an internal combustion engine,

Fig. 2 shows a schematic diagram of another fuel supply system of an internal combustion engine,

DK 181977 B1 8

Fig. 3 shows a schematic diagram of yet another fuel supply system of an internal combustion engine, and

Fig. 4 shows a schematic diagram of a first pressure signal and a second pressure signal.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Fig. 1 shows a schematic diagram of a fuel supply system 4 of an internal combustion engine 1 for propulsion of a vessel, such as a container ship or a tanker.

The internal combustion engine 1 may also be a stationary engine. The internal combustion engine 1 may thus be a two-stroke or four-stroke internal combustion engine 1. The internal combustion engine 1 comprises a first cylinder 2 and the fuel supply system 4. The fuel supply system 4 comprises a first cylinder fuel supply channel 5, 5a for supplying fuel to the first cylinder 2 and a second cylinder fuel supply channel 5, 5b for supplying fuel to the first cylinder 2. Thus, the first cylinder fuel supply channel 5, 5a is in fluid connection with the first cylinder 2 for injection of fuel into the first cylinder 2, and the second cylinder fuel supply channel 5, 5b is in fluid connection with the same first cylinder 2 for injection of fuel into the first cylinder 2 at a different position along the circumference of the first cylinder 2. The first cylinder fuel supply channel 5, 5a comprises a first primary valve 6, 6a and a first secondary valve 7, 7a arranged upstream of the first primary valve 6, 6a. The second cylinder fuel supply channel 5, 5b comprises a second primary valve 6, 6b and a second secondary valve 7, 7b arranged upstream of the second primary valve 6, 6b. Furthermore, the fuel supply system 4 comprises a first pressure sensor 8, 8a providing a first pressure signal 9, 9a, and the first pressure sensor 8, 8a is arranged for measuring the pressure between the first primary valve 6, 6a and the first secondary valve 7, 7a. Also, the fuel supply system 4 comprises a second pressure sensor 8, 8b providing a second pressure signal 9, 9b and arranged for measuring the pressure between the second primary valve 6, 6b and the second secondary valve 7, 7b. The internal combustion engine 1 further comprises a comparison unit 10 comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b for detecting any discrepancy between the first pressure signal 9, 9a and the second pressure signal 9, 9b indicating a leakage in one of the valves 6, 6a, 6b, 7, 7a, 7b. The comparison unit 10 receives the first

DK 181977 B1 9 pressure signal 9, 9a from the first pressure sensor 8, 8a and the second pressure signal 9, 9b from the second pressure sensor 8, 8b as indicated by dotted lines in

Fig. 1.

A small leakage in or malfunction of the primary valves 6, 6a, 6b or the secondary valves 7, 7a, 7b is difficult to detect but important because while the leakage is small, the damage is also very small and therefore only requires minor repair or displacement of only the leaking valve. Furthermore, a leakage in or malfunction of the secondary valves 7, 7a, 7b may cause a potential safety hazard. However, if the leakage or malfunction is not detected while being small, the repair becomes much more extensive and cost-intensive, and the vessel may even be prevented from operating while the repairs are made.

When the internal combustion engine 1 runs at low load and/or at low pressure, the pressure in the fuel supply system 4 does not build up to the same extent as when the engine runs at high load or at high pressure, such as 300 bar, when the valves 6, 7 are closed. Thus, more conventional methods of leak detection do not work sufficiently efficently.

In the known internal combustion engines, leak detection of the valves in the fuel supply channel supplying fuel to the cylinders is performed by way of several tests, such as a volume test, a drop test, a curve fit test, a variation test and a max pressure test, to be able to detect any leakage or malfunction at an early stage.

Especially the curve fit test has proved to be inadequate for engines running at low pressure and at low load.

However, by measuring and comparing the pressure or a representation thereof between the primary valve 6 and the secondary valve 7 on both the first cylinder fuel supply channel 5, 5a and the second cylinder fuel supply channel 5, 5b, a small leakage or malfunction can be detected as the surounding factors, such as low load and low pressure, equally affect the pressures in the first cylinder fuel supply channel 5, 5a and the second cylinder fuel supply channel 5, 5b, respectively, so that the pressure build-up does not have to be so high in order to also detect small leakages or any malfunction.

By measuring the pressure or a representation thereof between the primary valve 6, 6a, 6b and the secondary valve 7, 7a, 7b on both the first cylinder fuel supply

DK 181977 B1 10 channel 5, 5a and the second cylinder fuel supply channel 5, 5b, a leakage or malfunction can be detected while still being very small as the pressure signals can be compared, so even if the pressure signals 9a, 9b vary, the correlation between them will be significantly stable, even though the supply pressure varies or other factors around the fuel supply system 4 vary. In that way, an improved internal combustion engine 1 capable of detecting, in a simple manner, any leakage or malfunction of the valves 6, 7 in the fuel supply system 4 is obtained, and by such detection extensive damage and safety hazard can be avoided, which means that the internal combustion engine 1 is more cost-efficient as repair or replacement of the leaking or malfunctioning valve 6, 7 can be performed before major damage occurs. Furthermore, the present invention only requires one test.

The primary valve 6, 6a, 6b has an opening time period being shorter than an opening time period of the secondary valve 7, 7a, 7b. The secondary valve 7, 7a, 7b opens before the primary valve 6, 6a, 6b opens, and therefore the secondary valve 7, 7a, 7b is also called a window valve as it provides a window of fluid communication to the primary valve 6, 6a, 6b. Thus, the secondary valve 7, 7a, 7b opens while the primary valve 6, 6a, 6b is closed, and the secondary valve 7, 7a, 7b closes while the primary valve 6, 6a, 6b is closed. The primary valve 6, 6a, 6b opens and/or closes while the secondary valve 7, 7a, 7b is open.

The first pressure sensor 8, 8a measures a real-time and/or continuous first pressure signal 9, 9a, and the second pressure sensor 8, 8b measures a real-time and/or continuous second pressure signal 9, 9b. In this way, a leakage or malfunction can be detected any time during the opening and closing sequence of the valve 6, 6a, 6b, 7, 7a, 7b and while still being very small as the pressure signals 9, 9a, 9b can be compared at any given time during the sequence.

In Fig. 2, the internal combustion engine 1 comprises a first cylinder 2 and a second cylinder 3. The fuel supply system 4 comprises the first cylinder fuel supply channel 5, 5a for supplying fuel to the first cylinder 2 and the second cylinder fuel supply channel 5, 5b for supplying fuel to the second cylinder 3. The first cylinder fuel supply channel 5, 5a comprises the first primary valve 6, 6a, the first pressure sensor 8, 8a and the first secondary valve 7, 7a, and the second cylinder fuel supply channel 5, 5b comprises the second primary valve 6, 6b, the second pressure sensor 8, 8b and the second secondary valve 7, 7b. The first cylinder fuel supply channel 5, 5a is in fluid connection with the first cylinder 2 for injection of

DK 181977 B1 11 fuel into the first cylinder 2, and the second cylinder fuel supply channel 5, 5b is in fluid connection with the second cylinder 3 for injection of fuel into the second cylinder 3. In Fig. 2, the comparison unit 10 compares the first pressure signal 9, 9a of the first pressure sensor 8, 8a and the second pressure signal 9, 9b of the second pressure sensor 8, 8b for detecting any discrepancy between the first pressure signal 9, 9a and the second pressure signal 9, 9b. The first pressure signal 9, 9a corresponds to the pressure measured in the first cylinder fuel supply channel 5, 5a providing fuel to the first cylinder 2, and the second pressure signal 9, 9b corresponds to the pressure measured in the second cylinder fuel supply channel 5, 5b providing fuel to the second cylinder 3. Since the fuel is injected into the first cylinder 2 prior to being injected into the second cylinder 3, peaks of the first pressure signal 9, 9a will be timely displaced in relation to peaks of the second pressure signal 9, 9b.

In Figs. 1-3, the fuel supply system 4 further comprises a main supply channel 12 fluidly connected to the first cylinder fuel supply channel 5, 5a and the second cylinder fuel supply channel 5, 5b for supplying fuel from a pump 11. Thus, the main supply channel 12 is arranged upstream of the first cylinder fuel supply channel 5, 5a and upstream of the second cylinder fuel supply channel 5, 5b. The pressure of the fuel entering the first cylinder fuel supply channel 5, 5a may vary slightly from the pressure of the fuel entering the second cylinder fuel supply channel 5, 5b, but the correlation between the first pressure signal 9, 9a and the second pressure signal 9, 9b is the same as the difference in pressure will be significantly the same. Comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b will still give an early warning of any leakage in or malfunction of one of the valves 6, 6a, 6b, 7, 7a, 7b, and the leakage or malfunction detection is thus independent of such pressure variation in the main supply channel 12.

The internal combustion engine 1 of Fig. 3 comprises four cylinders, i.e. the first cylinder 2, the second cylinder 3, a third cylinder 14 and a fourth cylinder 15. Both the third cylinder 14 and the fourth cylinder 15 are fed fuel from two fuel supply channels 5, 5a, 5b via a first part 12a of the main supply channel 12 and a second part 12b of the main supply channel 12. Each of the two fuel supply channels 5, 5a, 5b has a pressure sensor 8, a secondary valve 7 and a primary valve 6. The fuel supply system 4 comprises the pump 11 supplying fuel to all four cylinders 2, 3, 14, 15 through the fuel supply channels 5, 5a, 5b.

DK 181977 B1 12

As can be seen in Fig. 4, the first pressure signal 9, 9a forms a first pattern P1, and the second pressure signal 9, 9b forms a second pattern P2. Comparing the first pattern P1 and the second pattern P2 will result in a correlation. The comparison unit 10 compares the first pattern P1 with the second pattern P2 in order to detect the correlation; if the correlation is within a predetermined interval, the valves 6, 6a, 6b, 7, 7a, 7b are working as planned, but if the correlation is outside the predetermined interval, there may be a leakage in or malfunction of one of the valves 6, 6a, 6b, 7, 7a, 7b. In Fig. 4, the correlation is a smaller value in the second pressure signal 9, 9b, and when continuously measuring and comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b, the pattern P1, P2 is the same, and the correlation is the same as long as the valves 6, 6a, 6b, 7, 7a, 7b are working as planned without any leakage or malfunction as shown in Fig. 4. If one of the first primary valve 6, 6a or the first secondary valve 7, 7a is not working according to plan, the first pressure signal 9, 9a will vary the first pattern P1, and the correlation will be outside the predetermined interval. As the first pattern P1 may vary due to fluctuation in the pressure elsewhere in the fuel supply system 4, such fluctuation will also affect the second pattern P2; when comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b, the correlation will be the same and within the predetermined interval if the variation is due to other variations elsewhere in the fuel supply system 4 and not due to a malfunction in one of the primary or secondary valves 6, 6a, 6b, 7, 7a, 7b. Thus, by comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b, small variations derived from a leakage in or malfunction of the primary valve 6, 6a, 6b or the secondary valve 7, 7a, 7b can be detected early as the predetermined interval of the correlation can be set very narrow because other system variations are levelled out when comparing the continuously measured first and second pressure, i.e. when comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b. If the first pressure signal 9, 9a was compared to another pressure signal, the system variations could affect only one of the pressure signals, and then the interval of the correlation had to be set significantly wider as the operation would otherwise be stopped too often, and then a small leakage or malfunction would likewise not be detected as early as when comparing the first pressure signal 9, 9a and the second pressure signal 9, 9b.

In Fig. 4, the first pressure signal 9, 9a has a predefined number of data points in a predefined time period when measured continuously and in real time. The second pressure signal 9, 9b is illustrated by a dotted line, but the second pressure signal

DK 181977 B1 13 9, 9b also has a predefined number of data points in the predefined time period when measured continuously and in real time. The predefined time period may be from the closing of the secondary valve 7, 7a, 7b (illustrated by an arrow C2 in Fig. 4) until the next closing of the secondary valve 7, 7a, 7b, as shown in Fig. 4, or any other period from one operation position until the same operation position occurs again, i.e. a sequence comprising one or all of the operation positions of the valves 6, 6a, 6b, 7, 7a, 7b, meaning and counting the entire operation positions in which the primary valve 6, 6a, 6b is both open and closed and in which the secondary valve 7, 7a, 7b is both open and closed. The closing of the primary valve 6, 6a, 6b is illustrated by an arrow C1, the opening of the primary valve 6, 6a, 6b is illustrated by an arrow O1, the opening of the secondary valve 7, 7a, 7b is illustrated by an arrow O2, and the closing of the secondary valve 7, 7a, 7b is illustrated by the arrow C2. The predefined time period may also be a shorter interval than a sequence comprising one or all of the operation positions of the valves 6, 6a, 6b, 7, 7a, 7b, e.g. from the closing of the primary valve 6, 6a, 6b as illustrated by the arrow C1 to the closing of the secondary valve 7, 7a, 7b as illustrated by the arrow C2.

Two similar valves 6, 6a, 6b, 7, 7a, 7b never function in completely the same way, and when setting up the fuel supply system 4, the cylinder 2, 3, 14, 15, etc., variations will occur from one fuel supply channel 5, 5a, 5b to another. By measuring and comparing the pressure in two comparable channels 5, 5a, 5b, a leakage in or malfunction of either the primary or the secondary valve 6, 6a, 6b, 7, 7a, 7b can be detected early. Variations in the pressure signal 9, 9a, 9b may be pressure variations due to the setup of the internal combustion engine 1 or the valve 6, 6a, 6b, 7, 7a, 7b itself, but once the internal combustion engine 1 and the valves 6, 6a, 6b, 7, 7a, 7b have been mounted and operate as intended, the pressure signal 9, 9a, 9b for one fuel supply channel 5, 5a, 5b with both a primary valve 6, 6a, 6b and a secondary valve 7, 7a, 7b will vary the same way as another fuel supply channel 5, 5a, 5b with both a primary valve 6, 6a, 6b and a secondary valve 7, 7a, 7b.

As mentioned above, the fuel is injected into the first cylinder 2 prior to being injected into the second cylinder 3, and peaks of the first pressure signal 9, 9a will then be timely displaced in relation to peaks of the second pressure signal 9, 9b.

Thus, by measuring and comparing the pressure in two comparable channels 5, 5a, 5b, where one supply channel 5, 5a, 5b supplies fuel to the first cylinder 2, and

DK 181977 B1 14 the other fuel supply channel 5, 5a, 5b supplies fuel to the second cylinder 3, the first pressure signal 9, 9a will be timely displaced from the second pressure signal 9, 9b. When comparing these pressure signals 9, 9a, 9b, the first pressure signal 9, 9a is timely displaced to match the pattern/sequence of the second pressure signal 9, 9b so that the opening and closing of the valves 6, 6a, 6b, 7, 7a, 7b is aligned.

The comparison unit 10 may be a central processing unit (CPU), a control unit, a comparative unit, or a hardware- or software-based comparator. The comparison unit 10 may use pattern recognition software.

The fuel supplied through the main supply channel 12 may be propane, ethene, ethane, butane, methanol, methane, ethanol, ammoniac, propylene, butylene, isobutane, n-butane, hydrogen, kerosene, nitromethane, liquefied petroleum gas, bioethanol or biodiesel. Thus, the fuel may be the only fuel supplied to the cylinders 2, 3, 14, 15, or a secondary fuel with the primary fuel being diesel, gasoline or petroleum. The fuel may be liquid or gas. The primary fuel may thus have a sulphur content of at least 0.05%.

The invention also relates to a leakage detection method for detection of a leakage in a valve 6, 6a, 6b, 7, 7a, 7b in a fuel supply system 4 for at least a first cylinder 2 and a second cylinder 3 of an internal combustion engine 1, in which method a first pressure signal 9, 9a is measured in a first time period by a first pressure sensor 8, 8a between a first primary valve 6, 6a and a first secondary valve 7, 7a on a first cylinder fuel supply channel 5, 5a of the fuel supply system 4, a second pressure signal 9, 9b is measured in the first time period or a second time period by a second pressure sensor 8, 8b between a second primary valve 6, 6b and a second secondary valve 7, 7b on a second cylinder fuel supply channel 5, 5b of the fuel supply system 4, and the first pressure signal 9, 9a is compared with the second pressure signal 9, 9b in order to detect a leakage in one of the valves 6, 6a, 6b, 7, 7a, 7b.

The invention also relates to a computer program product comprising a computer- readable medium holding computer program code means, and when loaded, said computer program product will make a computer execute the leakage detection method.

DK 181977 B1 15

Although the invention has been described above in connection with preferred embodiments of the invention, it will be evident to a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

DK 181977 B1 16 Patent claims

1. Internal combustion engine (1) for propelling a vessel, said internal combustion engine having at least one cylinder (2) and comprising: - a fuel supply system (4) comprising: - a first cylinder fuel supply channel (5, 5a) comprising a first primary valve (6, 6a) and a first secondary valve (7, 7a) arranged upstream of the first primary valve (6, 6a), and - a second cylinder fuel supply channel (5, 5b) comprising a second primary valve (6, 6b) and a second secondary valve (7, 7b) arranged upstream of the second primary valve (6, 6b), wherein a first pressure sensor (8, 8a) providing a first pressure signal (9, 9a) is arranged between the first primary valve (6, 6a) and the first secondary valve (7, 7a), and a second pressure sensor (8, 8b) providing a second pressure signal (9, 9b), is arranged between the second primary valve (6, 6b) and the second secondary valve (7, 7b), and characterized in that the internal combustion engine (1) further comprises a comparison unit (10) that compares the first pressure signal (9, 9a) with the second pressure signal (9, 9b) in order to detect discrepancies between the — first pressure signal (9, 9a) and the second pressure signal (9, 9b).

Internal combustion engine (1) according to claim 1, wherein the at least one cylinder is a first cylinder (2), and the internal combustion engine (1) further comprises a second cylinder (3).

3. An internal combustion engine (1) according to claim 2, wherein the first cylinder fuel supply channel (5, 5a) is in fluid communication with the first cylinder (2) and the second cylinder fuel supply channel (5, 5b) is in fluid communication with the first cylinder (2) or the second cylinder (3). 4. An internal combustion engine (1) according to any one of the preceding claims, wherein the fuel supply system (4) comprises a main supply channel (12) fluidly connected to the first cylinder fuel supply channel (5, 5a) and the second cylinder fuel supply channel (5, 5b).

DK 181977 B1 17

5. Internal combustion engine (1) according to any one of the preceding claims, wherein the first pressure sensor (8, 8a) is arranged to measure a real-time and/or continuous first pressure signal (9, 9a), and the second pressure sensor (8, 8b) is arranged to measure a real-time and/or continuous second pressure signal (9, 9b).

6. Internal combustion engine (1) according to any one of the preceding claims, wherein the fuel is propane, butane, methanol, methane, ethanol, ethane, ethene, ammonia, propylene, butylene, isobutane, n-butane, hydrogen, kerosene, nitromethane, liquefied petroleum gas, bioethanol or biodiesel.

Internal combustion engine (1) according to any one of the preceding claims, wherein the primary valve (6, 6a, 6b) has an opening period that is shorter than an opening period of the secondary valve (7, 7a, 7b).

238. An internal combustion engine (1) according to any one of the preceding claims, wherein the secondary valve (7, 7a, 7b) is arranged to open before the primary valve (6, 6a, 6b) is arranged to open.

9. Internal combustion engine (1) according to any one of the preceding claims, - wherein the first pressure signal (9, 9a) is arranged to form a first pattern (P1), and the second pressure signal (9, 9b) is arranged to form a second pattern (P2), and wherein the comparison unit (10) is arranged to compare the first pattern (P1) with the second pattern (P2) in order to detect a correlation and verify whether the correlation is within a predetermined range.

10. Leak detection method for detecting a leak in a valve (6, 6a, 6b, 7, 7a, 7b) in a fuel supply system (4) for supplying fuel to at least one cylinder (2) of an internal combustion engine (1) according to any one of the preceding claims, the method comprising: - measuring the first pressure signal (9, 9a) in a first period of time by means of the first pressure sensor (8, 8a) between the first primary valve (6, 6a) and the first secondary valve (7, 7a) on the first cylinder fuel supply channel (5, 5a) of the fuel supply system (4), - measuring the second pressure signal (9, 9b) in the first period of time or a second period of time by means of the second pressure sensor (8, 8b) between the second primary valve (6, 6b)

DK 181977 B1 18 and the second secondary valve (7, 7b) on the second cylinder fuel supply channel (5, 5b) of the fuel supply system (4), and - comparing the first pressure signal (9, 9a) with the second pressure signal (9, 9b) in order to detect a leak in one of the valves (6, 6a, 6b, 7, 7a, 7b).