Internal combustion engine

Abstract

The invention relates to an internal combustion engine for ship propulsion, the internal combustion engine having at least one cylinder and comprising a fuel supply system, the fuel supply system comprising: a first cylinder fuel supply passage comprising a first primary valve and a first secondary valve arranged upstream of the first primary valve; and a second cylinder fuel supply passage comprising a second primary valve and a second secondary valve arranged upstream of the second primary valve, a first pressure sensor providing a first pressure signal being arranged between the first primary valve and the first secondary valve, and a second pressure sensor providing a second pressure signal being arranged between the second primary valve and the second secondary valve. A first pressure sensor providing a first pressure signal is arranged between the first main valve and the first secondary valve, and a second pressure sensor providing a second pressure signal is arranged between the second main valve and the second secondary valve, and the internal combustion engine further comprises a comparison unit which compares the first pressure signal with the second pressure signal for detecting a difference between the first pressure signal and the second pressure signal. The invention also relates to a leak detection method for detecting a leak in a valve in a fuel supply system, and to a computer program product.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine for propelling a vessel, the internal combustion engine having at least one cylinder. The present invention also relates to a leak detection method for detecting valve leakage in a fuel supply system, and a computer program product. Background Art

[0002] When designing vessels such as container ships and tankers, the main concerns are on-board safety and prevention of environmental damage, while operating in a cost-saving manner. To operate in a safe and cost-saving manner, it is important to detect any faults in engine parts before they develop into serious defects that require replacement and before the faults affect other engine parts.

[0003] Minute leaks in fluid channels, valves, etc. are difficult to detect but are important because although the leaks are small, the damage is also small, so only minor repairs or replacement of the leaking valve, etc. are required instead of replacing related parts. However, if the leak, although small, is not detected, the repair work becomes more onerous and expensive, and the vessel may even be inoperable during the repair.

[0004] An internal combustion engine for propelling a vessel is shown in DK201970373. Summary of the Invention

[0005] An object of the present invention is to overcome all or part of the above-mentioned drawbacks and deficiencies of the prior art. More specifically, an object of the present invention is to provide an improved internal combustion engine that can detect any leakage of valves in the fuel supply system in a simple manner to avoid serious damage and potential safety hazards while still saving costs.

[0006] The above object and many other objects, advantages and features that are apparent from the following description are achieved by a solution according to the present invention by means of an internal combustion engine for vessel propulsion, the internal combustion engine having at least one cylinder and comprising:

[0007] - A fuel supply system, comprising:

[0008] - A first cylinder fuel supply passage, which includes a first main valve and a first secondary valve arranged upstream of the first main valve, and

[0009] - A second cylinder fuel supply passage, which includes a second main valve and a second secondary valve arranged upstream of the second main valve,

[0010] wherein a first pressure sensor providing a first pressure signal is arranged between the first main valve and the first secondary valve, and a second pressure sensor providing a second pressure signal is arranged between the second main valve and the second secondary valve, and

[0011] Wherein, the internal combustion engine further includes a comparison unit that compares the first pressure signal with the second pressure signal to detect a difference between the first pressure signal and the second pressure signal.

[0012] Moreover, at least one cylinder can be a first cylinder, and the internal combustion engine can further include a second cylinder.

[0013] In addition, a first cylinder fuel supply passage supplies fuel to one of the first cylinder and the second cylinder, and a second cylinder fuel supply passage supplies fuel to one of the first cylinder and the second cylinder.

[0014] In another internal combustion engine for vessel propulsion, the internal combustion engine can have at least a first cylinder and a second cylinder, and can include:

[0015] - A fuel supply system, which includes:

[0016] - A first cylinder fuel supply passage for supplying fuel to one of the first and second cylinders, which includes a first main valve and a first secondary valve arranged upstream of the first main valve, and

[0017] - A second cylinder fuel supply passage for supplying fuel to one of the first and second cylinders, which includes a second main valve and a second secondary valve located upstream of the second main valve,

[0018] Wherein, a first pressure sensor that provides a first pressure signal is arranged between the first main valve and the first secondary valve, a second pressure sensor that provides a second pressure signal is arranged between the second main valve and the second secondary valve, and

[0019] Wherein, the internal combustion engine further includes a comparison unit that compares the first pressure signal with the second pressure signal to detect a difference between the first pressure signal and the second pressure signal.

[0020] When the internal combustion engine operates at low load and / or low pressure, the pressure in the fuel supply system does not accumulate to the extent that it does when the engine operates at high load or high pressure (e.g., 300 bar when the valve is closed). Therefore, more traditional leak detection methods are not efficient enough. However, by measuring and comparing the pressures or their representations between the main valve and the secondary valve in the first cylinder fuel supply passage and the second cylinder fuel supply passage, small leaks or malfunctions can be detected because ambient factors (e.g., low pressure and low load) equally affect the pressures in the first cylinder fuel supply passage and the second cylinder fuel supply passage respectively, such that the pressure accumulation does not have to be too high to detect small leaks.

[0021] Leaks or malfunctions can be detected by measuring and comparing the pressures or their representations between the main valve and the secondary valve in the first cylinder fuel supply passage and the second cylinder fuel supply passage, even though the leaks or malfunctions are still very small, because the pressure signals can be compared, so that even if the pressure signals change, the correlation between them will be very stable, even if the supply pressure changes or other factors around the fuel supply system change.

[0022] In this way, an improved internal combustion engine is obtained, which is capable of detecting any leaks or malfunctions of the valves in the fuel supply system in a simple way, and through this detection, serious damage and safety hazards can be avoided, which means that the internal combustion engine is more cost-effective, because the valves with leaks or malfunctions can be repaired or replaced before major damage occurs.

[0023] In known internal combustion engines, leak detection of the valves in the fuel supply passages that supply fuel to the cylinders is carried out through various tests, such as volume tests, drop tests, curve fitting tests, change tests, and maximum pressure tests, so as to be able to detect any leaks or malfunctions at an early stage. In particular, the curve fitting test has been proven not to be applicable to engines operating at low pressures and low loads. The present invention only requires one test.

[0024] Moreover, the first cylinder fuel supply passage can be fluidly connected to the first cylinder, and the second cylinder fuel supply passage can be fluidly connected to the first cylinder or the second cylinder.

[0025] In addition, the first cylinder fuel supply passage can be fluidly connected to the first cylinder for injecting fuel into the first cylinder, and the second cylinder fuel supply passage can be fluidly connected to the first cylinder for injecting fuel into the first cylinder, or the second cylinder fuel supply passage can be fluidly connected to the second cylinder for injecting fuel into the second cylinder.

[0026] In addition, the fuel supply system can include a main supply passage fluidly connected to the first cylinder fuel supply passage and the second cylinder fuel supply passage.

[0027] Furthermore, the main supply passage can be arranged upstream of the first cylinder fuel supply passage and the second cylinder fuel supply passage.

[0028] In addition, the fuel supply system can include a pump, and the main supply passage can be fluidly connected to the pump for supplying fuel to the first cylinder fuel supply passage and the second cylinder fuel supply passage together.

[0029] In addition, the fuel supply system can include a pressure control valve, and the main supply passage can be fluidly connected to the pressure control valve for controlling the fuel flowing to the first cylinder fuel supply passage and the second cylinder fuel supply passage.

[0030] Moreover, the first pressure sensor can measure a real-time and / or continuous first pressure signal, and the second pressure sensor can measure a real-time and / or continuous second pressure signal.

[0031] In addition, the fuel can be propane, butane, methanol, methane, ethanol, ethylene, ethane, ammonia, propylene, butylene, isobutane, n-butane, hydrogen, kerosene, nitromethane, liquefied petroleum gas, bioethanol, or biodiesel.

[0032] Furthermore, the fuel can be the only fuel supplied to at least one cylinder.

[0033] Alternatively, the fuel can be a secondary fuel, and the primary fuel can be diesel, gasoline, or petroleum.

[0034] In addition, the sulfur content of the primary fuel can be at least 0.05%.

[0035] Moreover, the fuel can be liquid or gaseous.

[0036] Also, the opening period of the main valve can be shorter than the opening period of the secondary valve.

[0037] In addition, the secondary valve can open before the main valve opens.

[0038] Through the measurement and comparison of the present invention, leaks or malfunctions, especially of the secondary valve, can be monitored and detected, which is very difficult for known systems performing curve fitting tests. When using curve fitting tests, the measured pressure is usually compared with a reference curve; however, external factors such as operating at low load or low pressure will affect the result, such that the difference interval between the measured pressure and the reference curve must be very wide in order to also accommodate the operation of the engine at low load and low pressure. When the interval needs to be wide so that the engine does not stop unexpectedly, small leaks cannot be detected. Leaks in the secondary valve (also known as the window valve) can be a potential safety hazard, so it is very important to detect such leaks at an early stage.

[0039] Alternatively, the secondary valve can open when the main valve is closed.

[0040] In addition, the secondary valve can close when the main valve is closed.

[0041] Also, when the secondary valve is open, the main valve can be open and / or closed.

[0042] Moreover, the first pressure signal can form a first pattern, the second pressure signal can form a second pattern, and the comparison unit can compare the first pattern with the second pattern to detect a correlation and verify whether the correlation is within a predetermined interval.

[0043] "Association" refers to any statistical relationship between two sets of pressure signal data, such as statistical variance, that is, any type of association, which refers to the degree of linear correlation of a pair of variables.

[0044] Further, the comparison unit can be a central processing unit (CPU), a control unit, an integrated circuit (such as a microchip or a chip), a comparison unit, or a comparator based on hardware or software.

[0045] Moreover, the comparison unit can include pattern recognition software.

[0046] In addition, the internal combustion engine can further include a third cylinder and a fourth cylinder, each cylinder being supplied with fuel from two fuel supply channels, and each fuel supply channel having a pressure sensor, a secondary valve, and a main valve.

[0047] In addition, the internal combustion engine can further include at least six cylinders.

[0048] Furthermore, the first pressure signal can have a predetermined number of data points within a predetermined time period.

[0049] In addition, the second pressure signal can have a predetermined number of data points within a predetermined time period.

[0050] Moreover, the predetermined time period can be from the start of an operating position of one of the valves until the same operating position appears again.

[0051] Moreover, the predetermined time period can be from the closing of the secondary valve to the next closing of the secondary valve.

[0052] In addition, the internal combustion engine system can further include a turbocharger arranged downstream of the internal combustion engine.

[0053] In addition, the turbocharger can include a turbine and a compressor.

[0054] In addition, the present invention relates to a method for detecting leakage or failure of a valve in a fuel supply system for supplying fuel to at least one cylinder of an internal combustion engine, the method comprising:

[0055] - Measuring a first pressure signal within a first time period by a first pressure sensor between a first main valve and a first secondary valve on a first cylinder fuel supply channel of the fuel supply system,

[0056] - Measuring a second pressure signal within a first time period or a second time period by a second pressure sensor between a second main valve and a second secondary valve on a second cylinder fuel supply channel of the fuel supply system, and

[0057] - Comparing the first pressure signal with the second pressure signal in order to detect leakage or failure of one of the valves.

[0058] In addition, the present invention relates to a computer program product comprising a computer-readable medium storing means for computer program code, and when loaded, the computer program product will cause a computer to execute a leakage or fault detection method.

[0059] Furthermore, the internal combustion engine may be a large two-stroke internal combustion engine.

[0060] Alternatively, the internal combustion engine may be a large turbocharged two-stroke crosshead type internal combustion engine.

[0061] Further, the internal combustion engine may be a two-stroke or four-stroke internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The present invention and its many advantages will be described in more detail below with reference to the drawings, which show, for purposes of illustration, some non-limiting embodiments, in which:

[0063] Figure 1 A schematic diagram of a fuel supply system of an internal combustion engine is shown,

[0064] Figure 2 A schematic diagram of another fuel supply system of an internal combustion engine is shown,

[0065] Figure 3 A schematic diagram of yet another fuel supply system of an internal combustion engine is shown,

[0066] Figure 4 A schematic diagram of a first pressure signal and a second pressure signal is shown.

[0067] All the drawings are highly schematic and not necessarily drawn to scale, and they only show the parts necessary for clarifying the present invention, and other parts are omitted or only implied. DETAILED DESCRIPTION

[0068] Figure 1The figure shows a schematic view of a fuel supply system 4 for an internal combustion engine 1 for propelling a vessel (such as a container ship or an oil tanker). The internal combustion engine 1 can also be a stationary engine. Thus, the internal combustion engine 1 can be a two-stroke or four-stroke internal combustion engine 1. The internal combustion engine 1 includes a first cylinder 2 and a fuel supply system 4. The fuel supply system 4 includes a first cylinder fuel supply passage 5, 5a for supplying fuel to the first cylinder 2 and a second cylinder fuel supply passage 5, 5b for supplying fuel to the first cylinder 2. Thus, the first cylinder fuel supply passage 5, 5a is in fluid connection with the first cylinder 2 to inject fuel into the first cylinder 2, and the second cylinder fuel supply passage 5, 5b is in fluid connection with the same first cylinder 2 to inject fuel into the first cylinder 2 at different positions along the circumference of the first cylinder 2. The first cylinder fuel supply passage 5, 5a includes a first main valve 6, 6a and a first secondary valve 7, 7a arranged upstream of the first main valve 6, 6a. The second cylinder fuel supply passage 5, 5b includes a second main valve 6, 6b and a second secondary valve 7, 7b located upstream of the second main valve 6, 6b. In addition, the fuel supply system 4 includes a first pressure sensor 8, 8a providing a first pressure signal 9, 9a, and the first pressure sensor 8, 8a is arranged to measure the pressure between the first main valve 6, 6a and the first secondary valve 7, 7a. Moreover, the fuel supply system 4 includes a second pressure sensor 8, 8b providing a second pressure signal 9, 9b and arranged to measure the pressure between the second main valve 6, 6b and the second secondary valve 7, 7b. The internal combustion engine 1 further includes a comparison unit 10 that compares the first pressure signal 9, 9a and the second pressure signal 9, 9b for detecting any difference between the first pressure signal 9, 9a and the second pressure signal 9, 9b, which indicates a leak in one of the valves 6, 6a, 6b, 7, 7a, 7b. As shown by the dashed line in Figure 1 , the comparison unit 10 receives the first 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.

[0069] Small leaks or malfunctions in the main valves 6, 6a, 6b or the secondary valves 7, 7a, 7b are difficult to detect but important because, although the leak is small, the damage is also small, so only minor repairs or just the leaking valve need to be replaced. In addition, leaks or malfunctions in the secondary valves 7, 7a, 7b can pose a safety hazard. However, if the leak or malfunction cannot be detected due to its small size, the repair work will become more onerous and expensive, and the vessel may even be inoperable during the repair.

[0070] When the internal combustion engine 1 operates at low load and / or low pressure, the pressure in the fuel supply system 4 does not build up to the same extent as when the engine operates at high load or high pressure (e.g., 300 bar when the valves 6, 7 are closed). Therefore, more traditional leak detection methods are not efficient enough.

[0071] In known internal combustion engines, valves in the fuel supply channels supplying fuel to the cylinders are leak-detected by various tests, such as volume tests, drop tests, curve fitting tests, variation tests, and maximum pressure tests, so as to be able to detect any leaks or malfunctions at an early stage. In particular, the curve fitting test has proven to be unsuitable for engines operating at low pressure and low load.

[0072] However, small leaks or malfunctions can be detected by measuring and comparing the pressures or their representations between the main valves 6 and the secondary valves 7 on both the first cylinder fuel supply channels 5, 5a and the second cylinder fuel supply channels 5, 5b, because surrounding factors (such as low load and low pressure) equally affect the pressures in the first cylinder fuel supply channels 5, 5a and the second cylinder fuel supply channels 5, 5b respectively, such that the pressure build-up does not have to be too high to detect small leaks or any malfunctions.

[0073] By measuring the pressures or their representations between the main valves 6, 6a, 6b and the secondary valves 7, 7a, 7b on both the first cylinder fuel supply channels 5, 5a and the second cylinder fuel supply channels 5, 5b, leaks or malfunctions can be detected, even though the leaks or malfunctions are still very small, because the pressure signals can be compared, and thus the correlation between them will be very stable even if the pressure signals 9a, 9b change, even if the supply pressure changes or other factors around the fuel supply system 4 change. In this way, an improved internal combustion engine 1 is obtained, which can detect any leaks or malfunctions of the valves 6, 7 in the fuel supply system 4 in a simple manner, and serious damage and safety hazards can be avoided through such detection, which means that the internal combustion engine 1 is more cost-saving, because the valves 6, 7 with leaks or malfunctions can be repaired or replaced before major damage occurs. In addition, the present invention only requires one test.

[0074] The opening time of the main valves 6, 6a, 6b is shorter than the opening time of the secondary valves 7, 7a, 7b. The secondary valves 7, 7a, 7b open before the main valves 6, 6a, 6b open, so the secondary valves 7, 7a, 7b are also called window valves because it provides a fluid communication window with the main valves 6, 6a, 6b. Therefore, the secondary valves 7, 7a, 7b open when the main valves 6, 6a, 6b are closed, and the secondary valves 7, 7a, 7b close when the main valves 6, 6a, 6b are closed. The main valves 6, 6a, 6b open and / or close when the secondary valves 7, 7a, 7b are open.

[0075] The first pressure sensors 8, 8a measure real-time and / or continuous first pressure signals 9, 9a, and the second pressure sensors 8, 8b measure real-time and / or continuous second pressure signals 9, 9b. In this way, although still very small, leaks or malfunctions can be detected at any time during the opening and closing sequences of the valves 6, 6a, 6b, 7, 7a, 7b because the pressure signals 9, 9a, 9b can be compared at any given time during the sequence.

[0076] In Figure 2 , the internal combustion engine 1 includes a first cylinder 2 and a second cylinder 3. The fuel supply system 4 includes a first cylinder fuel supply passage 5, 5a for supplying fuel to the first cylinder 2 and a second cylinder fuel supply passage 5, 5b for supplying fuel to the second cylinder 3. The first cylinder fuel supply passage 5, 5a includes a first main valve 6, 6a, a first pressure sensor 8, 8a, and a first secondary valve 7, 7a, and the second cylinder fuel supply passage 5, 5b includes a second main valve 6, 6b, a second pressure sensor 8, 8b, and a second secondary valve 7, 7b. The first cylinder fuel supply passage 5, 5a is fluidly connected to the first cylinder 2 for injecting fuel into the first cylinder 2, and the second cylinder fuel supply passage 5, 5b is fluidly connected to the second cylinder 3 for injecting fuel into the second cylinder 3. In Figure 2 a comparison unit 10 compares the first pressure signal 9, 9a of the first pressure sensors 8, 8a with the second pressure signal 9, 9b of the second pressure sensors 8, 8b to detect any difference 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 passage 5, 5a that supplies fuel to the first cylinder 2, while the second pressure signal 9, 9b corresponds to the pressure measured in the second cylinder fuel supply passage 5, 5b that supplies fuel to the second cylinder 3. Since the fuel is injected into the first cylinder 2 before being injected into the second cylinder 3, the peak of the first pressure signal 9, 9a will be shifted in time relative to the peak of the second pressure signal 9, 9b.

[0077] In Figures 1-3In an internal combustion engine 1, a fuel supply system 4 further includes a main supply passage 12 which is fluidly connected to first cylinder fuel supply passages 5, 5a and second cylinder fuel supply passages 5, 5b for supplying fuel from a pump 11. Thus, the main supply passage 12 is arranged upstream of the first cylinder fuel supply passages 5, 5a and upstream of the second cylinder fuel supply passages 5, 5b. The pressure of the fuel entering the first cylinder fuel supply passages 5, 5a may be slightly different from the pressure of the fuel entering the second cylinder fuel supply passages 5, 5b, but the correlation between the first pressure signals 9, 9a and the second pressure signals 9, 9b is the same because the pressure difference will be significantly the same. Comparing the first pressure signals 9, 9a and the second pressure signals 9, 9b will still give an early warning of any leakage 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 changes in the main supply passage 12.

[0078] Figure 3 The internal combustion engine 1 includes four cylinders, namely a first cylinder 2, a second cylinder 3, a third cylinder 14 and a fourth cylinder 15. The third cylinder 14 and the fourth cylinder 15 are each supplied with fuel from two fuel supply passages 5, 5a, 5b via a first part 12a of the main supply passage 12 and a second part 12b of the main supply passage 12. Each of the two fuel supply passages 5, 5a, 5b has a pressure sensor 8, a secondary valve 7 and a main valve 6. The fuel supply system 4 includes a pump 11 which supplies fuel to all four cylinders 2, 3, 14, 15 via the fuel supply passages 5, 5a, 5b.

[0079] As Figure 4 shown, the first pressure signals 9, 9a form a first pattern P1 and the second pressure signals 9, 9b form a second pattern P2. Comparing the first pattern P1 and the second pattern P2 will result in a correlation. A comparison unit 10 compares the first pattern P1 with the second pattern P2 to detect the correlation; if the correlation is within a predetermined range, the valves 6, 6a, 6b, 7, 7a, 7b are operating as planned, but if the correlation is outside the predetermined range, there may be a leakage or malfunction of one of the valves 6, 6a, 6b, 7, 7a, 7b. In Figure 4 it, the correlation is a smaller value in the second pressure signal 9, 9b. When the first pressure signals 9, 9a and the second pressure signals 9, 9b are continuously measured and compared, the patterns P1, P2 are the same, and as long as the valves 6, 6a, 6b, 7, 7a, 7b are operating as planned without any leakage or malfunction, the correlation is the same, as Figure 4As shown. If one of the first main valves 6, 6a or the first secondary valves 7, 7a does not work as planned, the first pressure signals 9, 9a will change the first mode P1, and the correlation will be outside the predetermined range. Since the first mode P1 may change due to pressure fluctuations elsewhere in the fuel supply system 4, such fluctuations will also affect the second mode P2; when comparing the first pressure signals 9, 9a and the second pressure signals 9, 9b, if the change is due to changes elsewhere in the fuel supply system 4 rather than a failure of one of the main or secondary valves 6, 6a, 6b, 7, 7a, 7b, the correlation will be the same and within the predetermined range. Therefore, by comparing the first pressure signals 9, 9a and the second pressure signals 9, 9b, small changes caused by leaks or failures of the main valves 6, 6a, 6b or the secondary valves 7, 7a, 7b can be detected early, because the predetermined range of the correlation can be set very narrow, because when comparing the continuously measured first and second pressures, that is, when comparing the first pressure signals 9, 9a and the second pressure signals 9, 9b, other system changes are flattened. If the first pressure signals 9, 9a are compared with another pressure signal, the system changes may only affect one of the pressure signals, and then the correlation range must be set wider, because otherwise the operation will stop too frequently, and then small leaks or failures will not be detected as early as when comparing the first pressure signals 9, 9a and the second pressure signals 9, 9b.

[0080] In Figure 4 , the first pressure signals 9, 9a have a predetermined number of data points within a predetermined time period during continuous real-time measurement. The second pressure signals 9, 9b are shown as dashed lines, but the second pressure signals 9, 9b also have a predetermined number of data points within a predetermined time period during continuous real-time measurement. The predetermined time period can be from the closing of the secondary valves 7, 7a, 7b ( Figure 4 shown by arrow C2 in Figure 4 ) until the next closing of the secondary valves 7, 7a, 7b, as

[0081] Two similar valves 6, 6a, 6b, 7, 7a, 7b never work in exactly the same way, and when setting up the fuel supply systems 4, cylinders 2, 3, 14, 15, etc., there are variations from one fuel supply passage 5, 5a, 5b to another. By measuring and comparing the pressures in two similar passages 5, 5a, 5b, leaks or malfunctions in the main or secondary valves 6, 6a, 6b, 7, 7a, 7b can be detected early. A change in the pressure signals 9, 9a, 9b may be due to a pressure change caused by the internal combustion engine 1 or the settings of the valves 6, 6a, 6b, 7, 7a, 7b themselves. However, once the internal combustion engine 1 and the valves 6, 6a, 6b, 7, 7a, 7b are installed and operating as expected, the pressure signals 9, 9a, 9b of one fuel supply passage 5, 5a, 5b with the main valves 6, 6a, 6b and secondary valves 7, 7a, 7b will change in the same way as those of another fuel supply passage 5, 5a, 5b with both the main valves 6, 6a, 6b and secondary valves 7, 7a, 7b.

[0082] As described above, the fuel is first injected into the first cylinder 2 and then into the second cylinder 3, so the peak of the first pressure signals 9, 9a will be shifted in time relative to the peak of the second pressure signal 9, 9b. Thus, by measuring and comparing the pressures in two similar passages 5, 5a, 5b, where one supply passage 5, 5a, 5b supplies fuel to the first cylinder 2 and the other fuel supply passage 5, 5a, 5b supplies fuel to the second cylinder 3, the first pressure signal 9, 9a will be shifted in time from the second pressure signal 9, 9b. When comparing these pressure signals 9, 9a, 9b, the first pressure signal 9, 9a is shifted in time 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 are aligned.

[0083] The comparison unit 10 can be a central processing unit (CPU), a control unit, a comparison unit, or a hardware - or software - based comparator. The comparison unit 10 can use pattern recognition software.

[0084] The fuel supplied via the main supply passage 12 can be propane, ethylene, ethane, butane, methanol, methane, ethanol, ammonia, propylene, butene, isobutane, n - butane, hydrogen, kerosene, nitromethane, liquefied petroleum gas, bio - ethanol, or biodiesel. Thus, the fuel can be the sole fuel supplied to the cylinders 2, 3, 14, 15 or a secondary fuel, where the main fuel is diesel, gasoline, or petroleum. The fuel can be liquid or gas. Thus, the sulfur content of the main fuel can be at least 0.05%.

[0085] The invention also relates to a method for detecting leaks in valves 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 this method, during a first time period, a first pressure signal 9, 9a is measured by a first pressure sensor 8, 8a between a first main valve 6, 6a and a first secondary valve 7, 7a on a first cylinder fuel supply passage 5, 5a of the fuel supply system 4. During the first time period or a second time period, a second pressure signal 9, 9b is measured by a second pressure sensor 8, 8b between a second main valve 6, 6b and a second secondary valve 7, 7b on a second cylinder fuel supply passage 5, 5b of the fuel supply system 4, and the first pressure signal 9, 9a is compared with the second pressure signal 9, 9b to detect a leak in one of the valves 6, 6a, 6b, 7, 7a, 7b.

[0086] The invention also relates to a computer program product comprising a computer-readable medium storing computer program code means which, when loaded, will cause a computer to execute the leak detection method.

[0087] Although the invention has been described above in connection with preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications can be contemplated without departing from the invention as defined by the following claims.

Claims

1. An internal combustion engine (1) for ship propulsion, the internal combustion engine having at least one cylinder (2) and comprising: - A fuel supply system (4), comprising: - a first cylinder fuel supply passage (5, 5a) comprising a first main valve (6, 6a) and a first secondary valve (7, 7a) arranged upstream of said first main valve (6, 6a), and - a second cylinder fuel supply passage (5, 5b) comprising a second main valve (6, 6b) and a second secondary valve (7, 7b) arranged upstream of said second main valve (6, 6b), A first pressure sensor (8, 8a) providing a first pressure signal (9, 9a) is arranged between the first main 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 main 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), which compares the first pressure signal (9, 9a) with the second pressure signal (9, 9b) to detect a difference between the first pressure signal (9, 9a) and the second pressure signal (9, 9b).

2. The 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. The internal combustion engine (1) according to claim 2, wherein: The first cylinder fuel supply passage (5, 5a) is fluidly connected to the first cylinder (2), and the second cylinder fuel supply passage (5, 5b) is fluidly connected to 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) includes a main supply passage (12) fluidly connected to the first cylinder fuel supply passage (5, 5a) and the second cylinder fuel supply passage (5, 5b).

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

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

7. An internal combustion engine (1) according to any one of the preceding claims, wherein: The opening period of the main valve (6, 6a, 6b) is shorter than the opening period of the secondary valve (7, 7a, 7b).

8. An internal combustion engine (1) according to any one of the preceding claims, wherein: The secondary valve (7, 7a, 7b) is configured to open before the main valve (6, 6a, 6b) opens.

9. An internal combustion engine (1) according to any one of the preceding claims, wherein: The first pressure signal (9, 9a) is configured to form a first pattern (P1), and the second pressure signal (9, 9b) is configured to form a second pattern (P2), and wherein the comparison unit (10) is configured to compare the first pattern (P1) with the second pattern (P2) to detect a correlation and verify whether the correlation is within a predetermined interval.

10. A 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 a first pressure signal (9, 9a) within a first time period by means of the first pressure sensor (8, 8a) between the first main valve (6, 6a) and the first secondary valve (7, 7a) on the first cylinder fuel supply passage (5, 5a) of the fuel supply system (4), - measuring a second pressure signal (9, 9b) in the first time period or the second time period by means of the second pressure sensor (8, 8b) between the second main valve (6, 6b) and the second secondary valve (7, 7b) on the second cylinder fuel supply passage (5, 5b) of the fuel supply system (4), and - comparing said first pressure signal (9, 9a) with said second pressure signal (9, 9b) to detect a leak in one of said valves (6, 6a, 6b, 7, 7a, 7b).

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