A method for lubricating a large combustion engine and such large combustion engine

Abstract

A method for lubricating a large combustion engine, and such large combustion engine, the combustion engine having a lubrication system comprising - a lubricant supply (25), - a plurality of lubricant injectors (4), - a lubricant feed or supply conduit (9, 12) supplying lubricant to the lubricant injectors (4), - a controller (11). Each lubricant injector (4) comprises - an inlet port (4A, 112) flow-connected to the lubricant feed conduit (9), - a nozzle (5) with a nozzle aperture (5'). The method comprises the steps of - measuring the rotation of piston rings (216) of a piston (215) of the engine, - sending a signal for the rotation to the controller (11), - establishing data in the controller (11) for the rotation and for rotational speed of the piston rings (216), - establishing a number of desired values for lubricant amount, - comparing in the controller (11) the calculated actual amount to the desired value, - applying the data to determine need for cleaning by activating a cleaning sequence.

Description

[0001] A method for lubricating a large combustion engine and such large combustion engine

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a system for lubricating a large combustion engine, for example a large slow-running two-stroke engine, and a method of lubricating such engine and use thereof.

[0004] More specific the invention relates to a system which makes it possible to signal to a user that the piston ring pack needs cleaning.

[0005] In a further aspect the invention relates to a system which makes it possible to optimise an automatic cleaning sequence for cleaning a liner and piston rings in such combustion engine.

[0006] The invention relates to a method for lubricating a large combustion engine, for example a large slow-running two-stroke engine comprising a cylinder with a liner and a reciprocal piston having piston rings establishing contact with the liner inside the cylinder and with a lubrication system comprising

[0007] - a lubricant supply,

[0008] - a plurality of lubricant injectors distributed along a perimeter of the cylinder for injection of lubricant into the cylinder at positions on the perimeter during injection phases,

[0009] - a lubricant supply conduit connecting the lubricant supply with the lubricant injectors, the engine further comprising

[0010] - a controller for controlling the amount and timing of the lubricant injection by at least one of the lubricant injectors, wherein each lubricant injector comprises

[0011] - an inlet port flow-connected to the lubricant supply conduit for receiving lubricant from it,

[0012] - a nozzle with a nozzle aperture extending into the cylinder configured for injecting lubricant from the inlet port into the cylinder in the injection phase. Moreover, the invention relates to a large combustion engine, for example a large slow- running two-stroke engine comprising a cylinder with a liner and a reciprocal piston having piston rings establishing contact with the liner inside the cylinder and with a system comprising

[0013] - a lubricant supply,

[0014] - a plurality of lubricant injectors distributed along a perimeter of the cylinder for injection of lubricant into the cylinder at various positions on the perimeter during injection phases,

[0015] - a lubricant supply conduit connecting the lubricant supply with the lubricant injectors,

[0016] - a controller for controlling the amount and timing of the lubricant injection by at least one of the lubricant injectors,

[0017] - a computer to which the controller is connected, wherein each injector comprises

[0018] - an inlet port flow-connected to the lubricant supply conduit for receiving lubricant from it,

[0019] - a nozzle with a nozzle aperture extending into the cylinder configured for injecting lubricant from the inlet port into the cylinder in the injection phase when using the engine in cyclic operation, wherein the engine in the injection phase provides pressure-liquid to the lubricant supply conduit.

[0020] Preferably each injector comprises an adjustable valve at the nozzle for opening and closing for flow of lubricant to the nozzle aperture from a pressure chamber in the injector during an injection-cycle.

[0021] Here, "adjustable" means to the extent that it can be controlled how much the needle is pulled and how long it must be open. However, it is also possible to use other types of valves.

[0022] BACKGROUND OF THE INVENTION

[0023] Due to the focus on environmental protection, efforts are on-going with respect reduction of emissions from marine engines. This also involves the steady optimization of lubrication systems for such engines, especially due to increased competition. One of the economic aspects gaining increased attention is a reduction of oil consumption, not only because of environmental protection but also because this is a significant part of the operational costs of ships. A further concern is proper lubrication despite reduced lubricant volume because the longevity of engines should not be compromised by the reduction of oil consumption. Thus, there is a need for steady improvements with respect to lubrication.

[0024] For lubricating of large slow-running two-stroke marine diesel engines, several different systems exist, including injection of lubrication oil directly onto the cylinder liner or injection of oil quills to the piston rings.

[0025] An example of a lubricant injector for a marine engine is disclosed in EP1767751, in which a non-retum valve is used to provide the lubricant access to the nozzle passage inside the cylinder liner. The non-return valve comprises a reciprocating spring-pressed ball in a valve seat just upstream of the nozzle passage, where the ball is displaced by pressurised lubricant. The ball valve is a traditional technical solution, based on a principle dating back to the start of the previous century, for example as disclosed in GB214922 from 1923.

[0026] An alternative and relatively new lubrication method, compared to traditional lubrication, is commercially called Swirl Injection Principle (SIP). It is based on injection of a spray of atomized droplets of lubricant into the scavenging air swirl inside the cylinder. The helically upwards directed swirl results in the lubricant being pulled towards the Top Dead Centre (TDC) of the cylinder and pressed outwards against the cylinder wall as a thin and even layer. This is explained in detail in international patent applications W02010 / 149162 and W02016 / 173601. The injectors comprise an injector housing inside which a reciprocating valve member is provided, typically a valve needle. The valve member, for example with a needle tip, closes and opens the lubricant’s access to a nozzle aperture according to a precise timing. In current SIP systems, a spray with atomized droplets is achieved at a pressure of, typically, 35-40 bar. In comparison, the oil pressure is less than 30 bar and often less than 10 bar in systems working with compact oil jets that are introduced into the cylinder. In some types of SIP injectors, the high pressure of the lubricant is also used to move a spring-loaded valve member against the spring force away from the nozzle aperture such that the highly pressurised oil is released therefrom as atomized droplets. The ejection of oil leads to a lowering of the pressure of the oil on the valve member, resulting in the valve member returning to its origin and remaining there until the next lubricant cycle where highly pressurized lubricant is supplied to the lubricant injector again.

[0027] In such large marine engines, a number of injectors are arranged in the circumference of the cylinder, and each injector comprises one or more nozzle apertures for delivering lubricant jets or sprays into the cylinder from each injector. Examples of SIP lubricant injector systems in marine engines are disclosed in international patent applications W02002 / 35068, W02004 / 038189, W02005 / 124112, W02010 / 149162,

[0028] WO2012 / 126480, WO2012 / 126473, WO2014 / 048438, and W02016 / 173601.

[0029] Optimization of the spray in SIP lubrication is undergoing steady development. Although, lubrication injectors have some similarities with fuel injectors, comparison also shows different behaviour and different effects. This is mainly attributed to the different working conditions for the injectors, which leads to different effects such as viscosity, surface tension and liquid pressure. Accordingly, results from studies of fuel injection are not automatically transferable to lubricant injection, and the difference in behaviour is in some cases surprising.

[0030] For SIP injection, a precisely controlled timing is essential in addition to the objective of minimizing oil consumption. For this reason, SIP systems are specially designed for quick reactive response during injection-cycles.

[0031] Examination has shown that cylinder lubrication according to WO 0028194, so-called SIP lubrication, provides the highest oil film thickness in the cylinder where the wear is the greatest, corresponding to the piston being in top position and in the area of the uppermost piston ring. In contrast to this it has appeared that conventional lubrication or high-speed lubrication provides a thicker oil film on the rest of the travel surface.

[0032] The pressure existing by SIP lubrication is required in the lubricating oil lines between pumps and nozzles in order to ensure that the intended atomisation is considerably higher than the pressure by the conventional lubricating methods which operate with pressures of a few bars. SIP valves operate at a preset pressure of up to 60 bars, typically 35-40 bars.

[0033] The supplying of lubricating oil has furthermore the purpose of neutralising the acid action on the cylinder wall. The acid action arises by combustion of sulphur-containing fuels and they are best counteracted by supplying the lubricating oil directly at the top of the cylinder. Measurements shown that the SIP lubrication provides the least wear. In practice it appears that corrosive wear is the most critical factor for the service life of a cylinder when combusting sulphur-containing fuels.

[0034] A drawback of conventional lubrication or high-speed lubrication, which both are systems that mainly use the piston for distributing the lubricating oil, is that a certain excessive lubrication is needed in order to ensure sufficient lubricating oil for the top of the cylinder. In particular, lubrication on the piston requires an increase of the amount of lubricating oil in relation to the sulphur content of the fuel in order to achieve satisfactory cylinder conditions.

[0035] Correspondingly, for lubrication with systems where the lubricating oil is fed directly onto the cylinder wall it may be a disadvantage that an insufficient amount of oil is provided at the bottom of the cylinder when applying an amount of lubricating oil sufficient for obviating corrosive wear. This is because the piston rings, besides the above- mentioned distributing function, also produce a certain scraping action. Measurements show that SIP lubrication produce less scraping down of lubricating oil than lubrication with piston-distributed lubricating oil.

[0036] Furthermore, is has been realised that a further problem. The build-up of deposits in large slow-moving two-stroke engines has become a significant problem after the transition to Very Low Sulphur Fuel Oils (VLSFOs). VLSFO is often defined as fuels with a sulfur content from 0.1% up to and including 0.5% Sulphur. Hans Jensen Lubricators has a solution for this, namely the so-called "automatic cleaning sequence". This "automatic cleaning sequence" periodically increases cylinder oil consumption to flush out combustion residues and wear particles. However, this happens preventively at fixed intervals. There is not a continuously monitoring to show the actual need. It is common knowledge that piston rings can become stuck due to the formation of dirt. It is also well known that the rotation of a piston ring may be monitored and determined. This is stated in several sources: CIMAC 2013 paper No 367; ’’Design optimization in the solution of piston ring sticking and carbon deposit”; CIMMAC 1993 paper D44, Significance of recording and analysing the ring dynamics for the tribological optimisation of a piston ring package; SAE technical paper series 930796: ’’Effect of cylinder bore out-of-roundness on piston ring rotation and engine oil consumption”; Ali Kha- razmi, Michigan State University, 2017: ’’Three dimensional analysis of the gas flow in piston ring pack; Stewart Moore, BP Research & Engineering Centre. CIMAC Congress 1998 Copenhagen: “The complexities of piston ring lubrication in a large two-stroke marine diesel engine”; Sunghee Jung and Joonha Jin, Korea atomic energy research institute 1999; “Monitoring of rotational movements of two piston rings in a cylinder using radiotopes”; and Sulzer patent GB 1503255.

[0037] However, no sources teaches that the rotation can be used as an indicator before an excessive wear or damage occurs. However, this could happen, as the spring action in the piston ring and the combustion pressure will push the piston ring out against the surface of the liner with a relatively large force. Moreover, it seems that there is no large force contributing to the rotation of the piston ring.

[0038] With the introduction of the HJ Smartlube 4.0 system the performance of the lubrication systems is increased, however, there is a desire to obtain a method which in automatic way ensures that the system provides a desired amount of lubricant independent from external disturbances like change in lubricant type, pressure and temperature and mechanical wear of components in the lubrication system and which ensures that a large part of delivered lubricant oil is delivered in form of a spray.

[0039] If the fuel oil contains a higher amount of Sulphur, it may be advantageous to increase the amount of lubricating oil provided during the second injection phase where the swirl injection principle is used such that any residue and acid created by the combustion is effectively removed from the cylinder during each revolution of the engine. This will be further explained below with reference to a particular example. As there is a steady motivation for improvement of lubrication in large two-stroke gas and diesel engines, for example marine engines or engines for power plants, one may like to optimise the lubricant spray, in particular for SIP injection in order to flush out combustion residues and wear particles based on a continuously monitoring showing the build-up of such combustion residues and wear particles.

[0040] In GB 2345738 A a large combustion engine is described in which a pressure measurement is established and used for accurate adaptive control of the timing of the dosing of the lubricating oil in relation to piston passage for injection lubricating oil when the piston rings pass the lubricating point. Gas will flow past the piston ring at an inclined ring gap which generates periodical transient measuring data as the pressure drops at passage of each piston ring. Hereby a correct functioning of the piston rings is verified. However, the rotation of the piston ring is not used to evaluate whether there is a need for a cleaning sequence. Moreover, this prior art only described that one may monitor whether or not the piston ring rotates about the longitudinal axis of the piston. The teaching does not describe a measurement of the rotational speed of the piston ring.

[0041] In studies leading to the present invention it has been found beneficial to monitor the rotation of one or more piston rings and use this result in a continuously monitoring to show the actual need performing the so-called "automatic cleaning sequence" and to control the lubricating of a large combustion engine, for example a large slow-running two-stroke engine.

[0042] It is therefore desirable to provide a system which makes use of the measuring of the rotation of one or more piston rings in the control of the lubrication for cleaning the piston and piston rings.

[0043] The prior art documents do not disclose a method or a system for controlling the injector for obtaining that piston ring motion is used in controlling the cleaning process.

[0044] DESCRIPTION / SUMMARY OF THE INVENTION It is the objective of the invention to provide an improvement in the prior art systems in order to obtain an automatic cleaning sequence for the lubrication based on the actual need or to flush out combustion residues and wear particles.

[0045] Especially, it is the objective to improve lubrication with SIP injectors or lubrication with a common rail system in large combustion engines, for example in a large slow- running two-stroke engine.

[0046] However, the system according to the invention may also be used in large four-stroke combustion engines, for example marine engines or combustion engines for power plants.

[0047] These objectives are achieved by a method according to the invention for lubricating a large combustion engine, for example slow-running two-stroke engine, being peculiar in that the method comprises the steps of

[0048] - measuring the rotation of at least one of the piston rings,

[0049] - sending a signal for the rotation to the controller,

[0050] - establishing data in the controller for the rotation of the at least one piston ring, wherein the established data comprises data for the rotational speed of the at least one piston ring,

[0051] - applying the data for the rotation to determine a cleanliness of the piston rings and thus also to determine a need for cleaning,

[0052] - establishing a number of desired values for lubricant amount to be injected, typically specified as a feed rate, for specific operation mode,

[0053] - storing said desired values in a database in the controller,

[0054] - comparing in the controller the calculated actual amount to the desired value

[0055] - controlling the injectors and adjusting the setting thereof in order to obtain the desired values for lubricant amount to be injected for a specific operation mode,

[0056] - providing a signal that the piston ring pack needs cleaning and

[0057] - activating a cleaning sequence,

[0058] - which cleaning sequence comprises more parameters including timing, duration and distribution of the lubricant injection, wherein the step of activating the cleaning sequence either includes the step of - providing the signal that the piston ring pack needs cleaning to the user, for example shown in a monitoring facility and

[0059] - initiating by the user the cleaning sequence which initiation is based on the provided signal that the piston ring pack needs cleaning or includes the steps of

[0060] - providing the signal that the piston ring pack needs cleaning as signal registered in the controller and

[0061] - initiating, by the controller an automatic cleaning sequence which initiation is based on the provided signal that the piston ring pack needs cleaning.

[0062] The signal provided that the piston ring pack needs cleaning may be a signal forwarded to the user that the piston ring pack needs cleaning. This signal which may be shown in a monitoring facility and makes it possible for the user to initiate a cleaning sequence.

[0063] Alternatively, the signal provided that the piston ring pack needs cleaning may be a signal registered in the controller and which registered signal makes the controller to initiate an automatic cleaning sequence.

[0064] In both situations the activated cleaning sequence comprises more parameters including timing, duration and distribution of the lubricant injection.

[0065] The large combustion engine, for example a large slow-running two-stroke engine according to the invention is peculiar in that the engine further comprises

[0066] - detectors for measuring the rotation of at least one of the piston rings,

[0067] - a number of desired values for lubricant amount to be injected, typically specified as a feed rate, for specific operation mode, which desired values are stored in a database in the controller, and that the controller is arranged for comparing the calculated actual amount to the desired value and to control the injectors and adjust the setting thereof in order to obtain the desired values for lubricant amount to be injected for a specific operation mode,

[0068] - transmission lines for sending a signal for the rotation to the controller, which transmission lines are electronically or wirelessly transmission lines, wherein the engine, during use in cyclic operation is arranged for - establishing data in the controller for the rotation of the at least one piston ring, wherein the established data comprises data for the rotational speed of the at least one piston ring,

[0069] - applying the data for the rotation to determine a cleanliness of the piston rings and thus also to determine a need for cleaning and wherein the engine further comprises

[0070] - a device for activating a cleaning sequence, which cleaning sequence comprises more parameters including timing, duration and distribution of the lubricant injection, wherein the device for activating the cleaning sequence either comprises a monitoring facility which makes it possible for the user to initiate the cleaning sequence and which monitoring facility is arranged for receiving the signal that the piston ring pack needs cleaning org comprises the controller; the controller being arranged for registering the signal that “the piston ring pack needs cleaning” in the controller and the controller is arranged for and to initiate an automatic cleaning sequence based on the registered signal that “the piston ring pack needs cleaning”.

[0071] The lubricant supply conduit is preferably a common rail.

[0072] The lubricant supply is preferably a high-pressure unit. The high-pressure unit preferably comprises a pump.

[0073] The lubricating supply system is preferably the HJ Smartlube 4.0 system.

[0074] The invention may be used in a lubricating principle where the injectors receive pressurised lubrication oil from a lubricator through lubricant supply conduits, one for each injector.

[0075] The invention may also be used in a lubricating principle where the multiple lubricant supply conduits are substituted by a single common lubricant supply conduit. Then the conduit connections feeds lubricant to the injectors by a “common rail” system in which all injectors of an engine cylinder, or a subgroup of injectors for a single engine cylinder, are receiving lubricant through the single lubricant supply conduit in common and simultaneously. Optionally, there is provided a return line for back flow of lubricant from the injectors.

[0076] The large two-stroke engine comprises a cylinder with a reciprocal piston inside and with a number of lubricant injectors distributed along a perimeter of the cylinder for injection of lubricant into the cylinder at various positions on the perimeter during injection phases. For example, the engine is a marine engine or a large engine on a power plant. Typically, the engine is burning fuel oil.

[0077] The term injector is herein used for a lubricant injection valve system comprising a housing with a lubricant inlet and one single injection nozzle with a nozzle exit from which the lubricant leaves the nozzle into the cylinder as a spray, the nozzle exit having an exit aperture with an exit size S. For example, the exit aperture is circular with a diameter D, in which case the diameter D is a measure for the size S. If the exit aperture deviates from a circular shape, a potential measure for the size S is the aperture area or an averaged diameter; the latter being useful in case of slight oval or elliptical deviation from a circle. For example, for a noncircular exit aperture, the cross-sectional dimension is an equivalent diameter calculated as twice the square root of the ratio between the cross-sectional area and the number Pi~3.14. The nozzle has one or more, typically not more than two, nozzle exits.

[0078] In SIP injectors, the nozzle comprises a spray hole, formed as a channel with a length L, for example between 0.5 and 1 mm, one end of which forms the nozzle exit. In typical injectors, nozzle comprises a sac hole for flow of lubricant to the spray hole that extends from the sac hole to the nozzle exit. Typically, the central longitudinal axis of the spray hole has an angle with a central longitudinal axis of the sac hole, for example in the range of 30 to 90 degrees. The cross-sectional area of the sac hole perpendicular to its central longitudinal axis is often larger than the cross-sectional area of the spray hole perpendicular to its central longitudinal axis.

[0079] Optionally, a controller is provided as an add-on system for upgrade. The controller comprises a computer or is electronically or wirelessly connected to a computer. Advantageously, the computer is configured for monitoring parameters for the actual state and motion of the engine. In cooperation with the computer, on the basis of the parameters, the controller controls the amount and timing of the lubricant injection by the injectors during an injection phase. Optionally, the engine comprises a controller. As will become more apparent in the following, in advantageous embodiments, the controller is configured to also control the lubricant pressure and optionally also the temperature of the lubricant.

[0080] The method according to the invention may further include the step of providing for the engine

[0081] - providing in the at least one piston ring one or more radiotracers or magnetic pattern producing devices,

[0082] - detecting with a detector mounted on the engine the signals from the radiotracers or the magnetic pattern producing devices,

[0083] - determining the location of the radiotracers or the magnetic pattern producing devices relative to the cylinder and thus determining the rotation of the at least one piston ring.

[0084] The step of establishing data in the controller for the rotational speed of the at least one piston ring will provide data used in the controller for determining the cleanliness of the piston ring and thus the need of initiating a cleaning sequence.

[0085] The method according to the invention may further include the steps of

[0086] - obtaining further signals for heeling of a ship, engine load and possibly other signals, sending such further signals to the controller,

[0087] - establishing data in the controller for the heeling of the ship, engine load and possibly other parameters,

[0088] - combining the further signals with the signal for the rotation of the at least one piston ring to obtain combined data in the controller,

[0089] - applying he combined data to determine a cleanliness of the piston rings and thus also to determine a need for cleaning by activating the cleaning sequence to find the optimal result with minimal oil consumption.

[0090] The method according to the invention may further include the steps of

[0091] - using machine learning for determining when the piston ring pack needs cleaning and / or the parameters for the "cleaning sequence". In the large combustion engine, the device for activating the cleaning sequence may provide the user with a visual or an acoustic indication - or a combination thereof- and based on this indication the user initiates the cleaning sequence.

[0092] Alternatively the cleaning sequence is based on the registered signal to initiate an automatic cleaning sequence from the controller.

[0093] The large combustion engine according to the invention may further comprise

[0094] - in the at least one piston ring one or more radiotracers or magnetic pattern producing devices,

[0095] - at least one detector mounted on the engine and arranged to detect the signals from the radiotracers or the magnetic pattern producing devices.

[0096] The large combustion engine according to the invention may further comprise

[0097] - a computer to which the controller is connected, or alternatively

[0098] - a mobile phone arranged to communicate with the controller.

[0099] The large combustion engine according to the invention may further comprise a hydraulically driven inlet-valve system or an electrically driven inlet-valve system.

[0100] The large combustion engine according to the invention may further comprise that the controller is arranged for calibration of the injectors by measuring the lubricant amount injected at different injection-phases and mapping the results and using the results for determining the injection-phases for the injector in order to obtain the desired lubricant amount at an injection.

[0101] Such controlling of the amount of lubricant oil delivered in order to provide a more precise delivery of the desired lubricant amount in automatic way is described in WO 2023 / 088526 owned by the same applicant.

[0102] It is an advantage that the oil is atomized, so it is important to control how quickly a mass flow must increase, then you can control the cavitation and thereby also the atomization of the lubricant oil. It is advantageous not to stay in the area where there is no spray and therefore not a desired effect. In summary it is advantageous to have most of the injected lubricant oil injected as a spray by controlling the mass flow out of the injector. Such controlling is described in DK 202370281 filed by the same applicant.

[0103] Being able to accurately dose lubrication oil at from mg per injection and up, together with the fast rise and fall times for the mass flow is an advantage. Such dosing may be used in lubrication strategies for establishing quick automatic cleaning sequences based on a measurement of the rotation of one or more piston rings. Hereby it is possible to optimize the cleaning sequences with a minimum use of lubricant oil and simultaneously ensure an efficient continuously cleaning with the automatic cleaning sequence which periodically increases lubricant oil consumption to flush out combustion residues and wear particles.

[0104] When using adjustable valves in the injector means that it can be controlled how long time the valve must be open in order to optimize the used amount of lubricant oil . However, it is also possible to use other types of valves.

[0105] Optionally the system may also comprise a lubricant return line connecting the lubricant supply with the lubricant injectors.

[0106] In a specific embodiment the method of lubricating a large slow-running two-stroke engine includes the steps of providing for the engine

[0107] - a computer to which the controller is connected, or alternatively

[0108] - a mobile phone arranged to communicate with the controller.

[0109] In a specific embodiment the method of lubricating a large slow-running two-stroke engine includes the step of providing pressure-liquid through a common rail system where all injectors are connected to a common rail.

[0110] Moreover, the system may comprise:

[0111] - providing one flowmeter for all injectors in the engine, one flowmeter for all injectors in a cylinder or one flowmeter for each injector in the engine,

[0112] - measuring with the at least one flowmeter the lubricant flow,

[0113] - transforming in the controller the measured actual flow into an actual amount, Moreover, the system may comprise:

[0114] - providing one pressure gauge in the lubricant supply conduit,

[0115] - measuring with the at least one pressure gauge the pressure in the lubricant in lubricant supply conduit,

[0116] - transforming in the controller the measured pressure to a mass flow.

[0117] The measurement of the pressure in lubricant supply conduit may be used in the controller to ensure that a desired pressure is established by regulating the pump.

[0118] Alternatively, a pressure relief valve may be used to ensure that the pressure is maintained at the desired level in the lubricant supply conduit. Such pressure relief valve will be calibrated and adjusted before operation to the desired pressure for the injectors to be used.

[0119] So, more methods may be used for keeping a desired constant pressure in the lubricant supply conduit.

[0120] The controller may be built into the injector or may be connected to the injector.

[0121] The controller may be connected to the flowmeter by wiring or in a wireless way.

[0122] The controller may also be arranged for controlling the lubricant type used.

[0123] In some embodiments, the maximum possible retraction position of the plunger is the most rearward possible position at maximum distance from the nozzle aperture, but it is possible that the plunger is held at a distance from the most rearward possible position.

[0124] By regulating the distance, the injection amount for the next injection is regulated, as the stroke length is reduced relatively to the maximum possible retraction position. The effect is similar to the screw-adjustable end-stop in W002 / 35068, however, the stroke length adjustment mechanism can be provided centrally and remotely from the injector, which is in contrast to the injector of W002 / 35068. The engine and the method may comprise the hydraulically driven inlet-valve system known from WO 2019 / 114905.

[0125] The engine and the method may comprise electrically-driven inlet-valve system known from WO 2019 / 114903.

[0126] In some embodiments the engine is peculiar in that the lubricant system is chosen from mechanically driven systems, hydraulically driven systems and common-rail systems.

[0127] The principle according to the invention is flexible and may be used in different lubrication systems.

[0128] In some embodiments the method comprises that the regulation of the amount of lubricant is controlled by a feedback control / regulation, for example a PID regulation or a more sophisticated model-based regulation.

[0129] The method and the engine according to the invention is especially suitable for use for SIP injection into the cylinder of a large marine engine or combustion engine for a power plant at a lubricant pressure in the range of 10 bar to 400 bar, preferably a range of 25 bar to 100 bar. The method is also suitable for lubrication with a combination of SIP injection and injection into the ring pack.

[0130] Definitions

[0131] The term “regulate” refers to a situation where the lubricant amount is amended in order to correspond to a desired amount when the engine is in service.

[0132] The term “adjust” refers to the situation where the lubricant amount is amended when the injectors are calibrated.

[0133] The term “injector” is used for an injection valve system comprising a housing with a lubricant inlet and one single or more injection nozzles with a nozzle aperture as a lubricant outlet and with a movable valve member inside the housing, which opens and closes access for the lubricant to the nozzle aperture. Although, the injector has a single nozzle that extends into the cylinder - however is embedded in the cylinder wall to ensure free movement of the piston - through the cylinder wall, when the injector is properly mounted, the nozzle itself, optionally, has more than a single aperture. For example, nozzles with multiple apertures are disclosed in WO2012 / 126480.

[0134] The term “injection-phase” is used for the time during which lubricant is injected into the cylinder by an injector.

[0135] The term “idle-phase” is used for the time between injection-phases.

[0136] The term “idle state” is used for the state of a component in the idle-phase.

[0137] The term “idle-phase position or orientation” is used for the position or orientation of a movable component when in the idle state during the idle-phase, which is in contrast to an injection-phase position.

[0138] The term “injection cycle” is used for the time it takes to start an injection sequence and until the next injection sequence starts. For example, the injection sequence comprises a single injection, in which case the injection cycle is measured from the start of the injection-phase to the start of the next injection-phase. Alternatively, the injection sequence comprises multiple injections, for example multiple injections above the piston before the piston passes the injectors on its way to the TDC, for example a first injection with one lubricant followed by another injection of another lubricant, and potentially further lubricants and / or additives. Such double or multiple injections leads to oil mixing in the cylinder before the piston reaches the TDC. For example, there is one injection cycle for each revolution of the engine. However, it is also possible to have one injection cycle after a number of engine revolutions.

[0139] The term “timing” of the injection is used for the adjustment of the start of the injectionphase by the injector relatively to a specific position of the piston inside the cylinder.

[0140] The term “frequency” of the injection is used for the number of repeated injections by an injector per revolution of the engine. If the frequency is unity, there is one injection per revolution. If the frequency is 1 / 2, there is one injection per every two revolutions. This terminology is in line with the above-mentioned prior art. The term “pressurized lubricant” is used for lubricant provided at a pressure high enough that it can be used for injection as an atomized spray into the cylinder. For SIP injection, the pressure is typically higher, for example above 25 bar.

[0141] The term “flowmeter” is used for a component which is able to measure a flow independent of the method used, e.g. pressure difference, viscosity, temperature, amount.

[0142] The term “pressure gauge” is used for a component which is able to measure a pressure in lubricant oil independent of the method used, e.g. also for determining of pressure difference.

[0143] Practical embodiments

[0144] The large engine, for example slow-running two-stroke engine, optionally a marine engine or engine for a power plant, comprises a cylinder with a reciprocal piston inside and with a plurality of lubricant injectors fixed to a wall of the cylinder and extending through the cylinder wall. The injectors are distributed along a perimeter of the cylinder and configured for injection of lubricant into the cylinder at various positions on the perimeter during injection-phases. For example, the large engine, such as slow-running two-stroke engine, is a marine engine or a large engine in power plants. Typically, the engine is burning diesel or gas fuel, for example natural gas fuel.

[0145] The engine comprises also a lubricant supply with a pressurized lubricant, typically pressurized by a lubricant feed pump. Optionally, the engine comprises more than one lubricant supply with correspondingly more than one type of lubricant, and correspondingly more than one lubricant feed pump.

[0146] Each of the plurality of injectors is connected with each of its lubricant inlets to lubricant supply through a corresponding lubricant supply conduit. Each lubricant supply includes a potential pressure source, typically lubricant pump, which raises the pressure of the corresponding lubricant to an adequate level. For the described system, it suffices to provide a constant lubricant pressure at the corresponding lubricant inlet of the injector. The injectors are configured for the type of lubricant to be injected. The inlet can be used to provide and add not only lubricants but also potential additives. For example, the injector optionally has more inlets of which one is used for lubricants, such as lubricant oils, and one is used for an additive. The injectors comprise a nozzle having one or more nozzle apertures for injecting lubricant oil into the cylinder in form of a spray.

[0147] The engine further comprises a controller. The controller is configured for controlling the pressure in the lubricant oil and mass flow of lubricant oil.

[0148] The controller may also be configured for controlling the amount and timing of the injection of the lubricant by the plurality of injectors. Optionally, also the injection frequency is controlled by the controller.

[0149] For precise injection, it is an advantage if the controller is electronically connected to a computer or comprises a computer, where the computer is monitoring parameters for the actual state and motion of the engine. Such parameters are useful for the control of optimized injection.

[0150] Optionally, the controller is provided as an add-on system for upgrade of already existing engines.

[0151] A further advantageous option is a connection of the controller to a Human Machine Interface (HMI) which comprises a display for surveillance and input panel for adjustment and / or programming of parameters for injection profiles and optionally the state of the engine.

[0152] Electronic data connections are optionally wired or wireless or a combination thereof.

[0153] In a concrete embodiment, the injector comprises a lubricant inlet for receiving the lubricant from a lubricant supply conduit for injection of the lubricant into the cylinder. The lubricant inlet of the injector is connected to the lubricant supply though the lubricant supply conduit. The injector has a lubricant flow path from the lubricant inlet to the at least one nozzle and the nozzle aperture for lubricant flow from the lubricant inlet through the at least one nozzle into the cylinder.

[0154] The injector comprises one nozzle or more than one nozzle, for example two nozzles. Each nozzle has a nozzle aperture, extending into the cylinder for lubricant injection in an injection-phase. Optionally, a nozzle has more than a single aperture. For example, nozzles with multiple apertures are disclosed in WO2012 / 126480. In some embodiments, the injector comprises a single nozzle with a single nozzle aperture.

[0155] In particular, each injector comprises an internal actuator-driven valve system in the lubricant flow path, wherein the valve system is configured for selectively switching from the idle state without injection to an injection state with injection of the lubricant, into the cylinder through the at least one nozzle in the injection-phase in dependence of the received injection-phase signals.

[0156] Each injector comprises an actuator for driving the valve system. The actuator is functionally connected to the controller and configured for being activated by the controller for selectively driving the valve system and causing injection of the lubricant under control by the controller as a consequence of the activation of the actuator by the controller. The valve system, under control by the controller, is used for selecting which amount and timing to be used for injections and in which sequence.

[0157] In operation, the actuator is activated by the controller for starting an injection-phase with the lubricant. As a consequence, the valve system is caused to open for flow of the lubricant through the flow path and injecting the lubricant into the cylinder. At the end of the injection-phase, the actuator is caused to close the valve system and stop lubricant supply. control

[0158] In a specific embodiment the engine comprises a lubricant supply conduit containing lubricant at a first pressure and a pressure-control conduit containing pressure-liquid at a pressure higher than the first pressure. In such case the injector comprises an internal hydraulic-driven pumping system where the pressure-liquid is used for driving the pumping system inside the injector housing by which the lubricant is pressurized in the injector and ejected therefrom. The injector comprises a lubricant inlet port, flow-connected to the lubricant supply conduit for receiving lubricant from it for injection into the cylinder. The injector also comprises a pressure-control port, flow-connected to the pressure-control conduit for receiving pressure-liquid therefrom in the injection phase.

[0159] The injector comprises the front chamber inside the injector between the lubricant inlet port and the outlet-valve system for receiving and accumulating a pre-determined volume of lubricant from the inlet port prior to an injection phase.

[0160] A pressure chamber in the injector is in communication with the pressure-control port for receiving the pressure-liquid from the pressure-control port in the injection phase. The pressure-liquid in the pressure chamber drives a pumping system in the injector.

[0161] The pumping system comprises a reciprocal hydraulic-driven actuator-plunger in contact with the pressure chamber and pre-stressed by a spring-load from an actuatorplunger spring and configured for being driven, for example in a direction towards the nozzle, by the pressure-liquid in the pressure chamber in the injection phase, by which it is causing pressure rise in the lubricant in the front chamber above the predetermined limit and causes pumping of this predetermined lubricant volume through the non-return valve and the nozzle aperture into the cylinder.

[0162] Injection

[0163] Optionally, the injection phase comprises multiple injections, for example multiple injections above the piston before the piston passes the injectors on its way to the TDC, for example a first injection with lubricant followed by another injection of the lubricant, and potentially further lubricants and / or additives. Such double or multiple injections, especially when in SIP operation, leads to oil mixing in the cylinder before the piston reaches the TDC.

[0164] The variety of selecting lubricant for injection, its amount and its timing as controlled by the controller makes a high variety of injection sequences possible, for example combinations of at least two of:

[0165] - one or more injections under the piston,

[0166] - one or more injections onto the piston, - one or more injections above the piston during a single injection cycle.

[0167] For the various injections, also the selections for the lubricant or lubricants, potentially with additives, can be varied,

[0168] For example, the actuator is an electrically controlled actuator and is electrically connected to the controller by an electrical connection for receiving injection-phase signals from the controller, the injection-phase signals indicating the timing for the injection. For the injection-phase, an electrical control signal is sent from the controller to each of the injectors for starting an injection-phase with the lubricant. As a consequence thereof, the valve system opens for flow of the corresponding lubricant through the flow path and injects it into the cylinder. At the end of the injection-phase, the electrical control signal from the controller to the injector is changed, causing the valve system to close for lubricant injection and return to the idle state.

[0169] Optionally, the actuator comprises an electrical solenoid arrangement with a stationary solenoid part and a movable solenoid part. The valve system is connected to the movable solenoid part for being driven by the actuator upon electrical excitation of the solenoid, wherein the solenoid is configured for excitation by the injection-phase signals from the controller.

[0170] The term “a solenoid coil” should be understood as “at least one solenoid coil”, as it is possible and, in some cases, advantageous to use more than one coil, for example two or three coils.

[0171] The term “signal” from the controller is used here for an electrical current that flows from the controller to the injector. In some embodiments, the signal itself can be used for driving the actuator, for example an electromechanical actuator, if the current is sufficiently strong. For example, for switching the driving direction of an electromechanical actuator, the direction of the current is switched to an opposite direction. However, alternatively, the injector could comprise an electro- switch where the signal from the controller opens for flow of a current sufficiently strong to drive the actuator. In the latter case, the signal lines from the controller to the electro- switch can be accomplished by very thin wiring. Alternatively, the term “signal” also is used for a wireless signal. Alternatively, the actuator is a hydraulic or pneumatic actuator. Such hydraulic or pneumatic actuator in the injector is, optionally, also electrically controlled. For example, an electrical signal from the controller to the injector causes an electromechanical actuatorvalve of the inj ector to open for hydraulic or pneumatic flow into the actuator for driving the valve system hydraulically or pneumatically. Optionally, an electrical signal from the controller to the injector causes an electromechanical actuator-valve to open for hydraulic or pneumatic flow into the actuator for driving the actuator itself, which then, in turn, by a mechanical connection drives the valve system.

[0172] In some embodiments, the valve system is configured to select only one injector at a time among multiple injectors for supply of lubricant and for injection thereof. In some embodiment, alternatively or in addition, the valve system is configured to select more than one injector at a time among multiple injectors for supply of lubricant and for injection thereof in order to inject simultaneously multiple lubricants or lubricant in combination with additive.

[0173] In some embodiments, the injector has more than one nozzle, and multiple lubricants and additives can be injected into the cylinder through separate nozzles of the injector. In other embodiments, multiple lubricants and additives are injected into the cylinder through a single nozzle and potentially mixed inside the injector prior to ejection from the nozzle aperture.

[0174] In practical embodiments, the injector comprises a base and a rigid, optionally cylindrical, flow chamber, which is rigidly connecting the base with the nozzle for fixing the nozzle inside the cylinder wall when the base is fixed to the cylinder wall. Due to the base being provided at the opposite end of the flow chamber relatively to the nozzle, it is typically located on or at the outer side of the cylinder wall. For example, the injector comprises a flange at the base for mounting onto the outer cylinder wall. Alternatively, in order to mount the injector in the cylinder wall, the injector comprises a flange provided around the flow chamber. For example, the flange is bolted against the cylinder wall.

[0175] Advantageously, the base comprises the first and second inlet and the potential further inlets. The flow chamber is hollow and contains the flow path for lubricant flow from the lubricant inlet through the flow chamber and to the nozzle for injection of the lubricant into the cylinder. Optionally, the valve member is located in the flow chamber or in the base.

[0176] For example, the actuator is provided outside the cylinder wall when the injector is mounted at the cylinder wall. Optionally, it is fixed to the base.

[0177] In practice, the injection-phase signal is received by the actuator, causing the actuator to move the valve member in dependence of the injection-phase signal to an injectionphase position or orientation, which leads correspondingly to opening of the flow path for injection of the lubricant into the cylinder.

[0178] For example, the actuator is mechanically connected to the sei ection- valve member by an actuator extension for driving the valve member by the actuator extension. This is advantageous if the valve member is located in the flow chamber and, thus, inside the cylinder wall, whereas the actuator is located outside the cylinder wall. In this embodiment, the operation comprises moving the valve member by the actuator by using the actuator extension.

[0179] Outlet-valve system

[0180] Optionally, each of the injectors comprises an outlet-valve system at the nozzle configured for opening for flow of lubricant to the nozzle aperture during an injection-phase upon pressure rise above a predetermined limit at the outlet-valve system and for closing the outlet-valve system after the injection-phase when the pressure drops. The outletvalve system closes off for back-pressure from the cylinder and also prevents lubricant to enter the cylinder in the idle-phase between injection-phases. In addition, the outletvalve system assists in a short closing time after injection, adding to precision in timing and volume of injected lubricant.

[0181] In these embodiments, the injector comprises a lubricant flow path from the lubricant inlet through the valve system and to the outlet-valve system for flow of the lubricant from the lubricant inlet, through the valve system and the outlet-valve system and out of the injector at the nozzle aperture. The valve system is arranged as part of the injector upstream of and optionally spaced from the nozzle. Optionally, the valve system is arranged upstream of and spaced from the outlet-valve system.

[0182] For example, the outlet-valve system comprises an outlet non-return valve. In the outlet non-return valve, the outlet-valve member, for example a ball, ellipsoid, plate, or cylinder, is pre-stressed against an outlet-valve seat by an outlet-valve spring. Upon provision of pressurised lubricant in a flow chamber upstream of the outlet-valve system, the pre-stressed force of the spring is counteracted by the lubricant pressure, and if the pressure is higher than the spring force, the outlet-valve member is displaced from its outletvalve seat, and the outlet non-return valve opens for injection of lubricant through the nozzle aperture into the cylinder. For example, the outlet-valve spring acts on the outletvalve member in a direction away from the nozzle aperture, although, an opposite movement is also possible.

[0183] For example, for lubricating the engine, the method comprises sending an electrical control signal from the controller to the injector and by the control signal causing the injector to open the valve system for flow of lubricant from the lubricant supply conduit through the lubricant inlet, through the valve system, and into a conduit that flow-connects the valve system with the outlet-valve system.

[0184] It is noted that the pressure of the lubricant in the lubricant supply conduit is above the predetermined limit that determines the opening of the outlet-valve system in order for the lubricant supply conduit to provide lubricant through the valve system with a pressure sufficiently high to open the outlet-valve system in the injection-phase. Accordingly, the lubricant flow through the valve system and into the conduit between the valve system and the outlet-valve system causes a pressure rise at the outlet-valve system, causing the outlet-valve system to open for flow of lubricant from the conduit to the nozzle aperture by which lubricant is injected into the cylinder through the nozzle aperture. At the end of the lubrication period, the electrical control signal from the controller is changed, causing the valve system to close again for lubricant supply from the lubricant inlet to the nozzle aperture. The pressure in the conduit decreases again, and the outlet-valve system closes. In these embodiments, there are at least two valve systems in the injector. The valve system is regulated under control by the controller, for example by electrical signals from the controller, and the outlet-valve system is activated only by the elevated pressure of the lubricant at the outlet-valve system, once the valve system has opened and caused flow of lubricant at elevated pressure from the lubricant supply conduit to the outlet-valve system. There is no mechanical connection that couples the movable parts of the valve system with movable parts of the outlet-valve system. Coupling between the opening and closing of these two systems is done only by the lubricant that flows from the valve system to the outlet-valve system.

[0185] Optional details of valve and actuator

[0186] In some practical embodiments, the valve system comprises a movable, actuator-driven valve member arranged for moving from an idle-phase position, in which the valve member in the idle-phase blocks the flow path, to an injection-phase position, in which the valve member opens the flow path for flow of lubricant through the flow path in the injection-phase. Advantageously, the valve member is pre-stressed towards an idle- phase position by a valve spring.

[0187] In some embodiments, for driving the movable valve member, the injector comprises a movable and actuator-driven rigid actuator-extension that is connecting the actuator with the valve system and which is used by the actuator for displacing or rotating the valve member from an idle-phase position, in which the valve member blocks the flow path, to an injection-phase position, in which the valve member opens the flow path for flow of a lubricant through the flow path for injection of the lubricant into the cylinder in an injection-phase.

[0188] Optionally, the actuator-driven rigid actuator-extension is a pull-push-member for selectively pulling or pushing the valve member in the injection. Alternatively, the actuator extension is a rotational member transferring the driving force from a rotational actuator for example selectively in one direction or the other.

[0189] In some embodiment, the actuator is an electrically controlled actuator, for example an electromechanical actuator. Optionally, the actuator comprises an electrical solenoid arrangement with a stationary solenoid part and a movable solenoid part and wherein the actuator-extension is connected to the movable solenoid part for being driven by electrical excitation of the solenoid, wherein the solenoid is configured for excitation by the injection-phase signals from the controller.

[0190] For example, the valve system comprises a linear actuator for driving the actuator-ex- tension. In this case, the actuator-extension is connected to the actuator, for example to an arrangement of a solenoid-plunger and solenoid coil, for upon electrical activation of the actuator to drive the actuator-extension, for example pull-push-member for open for flow from the lubricant inlet. Optionally, the actuator-extension is connected to the solenoid-plunger, whereas the solenoid coil is stationary in the injector. Alternatively, the actuator-extension is connected to the solenoid coil, which is movable together with the actuator-extension.

[0191] As alternative, piezo-electric elements can be used for driving the valve member. Such elements are electrically or wireless connected to the controller for being controlled by the controller with respect to when to contract or expand. With piezo-electric actuators very high forces may be obtained. For example, in the size of 10000 N. The force may also be higher as this will result in a shorter time for obtaining the operational situation with cavitation in the injection and thereby a very quick start of the injected lubricant oil to be in form of a spray.

[0192] In some concrete embodiments, the valve member is cylindrical and comprises a stationary valve member, which, in turn, comprises a corresponding cylindrical bushing inside which the cylindrical valve member is arranged for displacement along a longitudinal axis of the bushing or arranged for rotation about longitudinal axis of the bushing.

[0193] The term cylindrical bushing is used for describing that the bushing has a cylindrical hollow, typically but not necessarily with a circular cross section. The cylindrical valve member fits tightly into the cylindrical hollow of the bushing so that no lubricant can flow between the cylindrical valve member and the cylindrical bushing apart from a potential minimal amount that is only lubricating the valve member inside the bushing and which is negligible as compared to the amount of lubricant injected into the cylinder. System advantages

[0194] The system as described herein has a number of advantages.

[0195] By providing a lubricating system well known techniques for measuring the rotation of at least one of the piston rings may be used for establishing a signal to the user that the piston ring pack needs cleaning. This signal which may be shown in a monitoring facility makes it possible for the user to initiate a cleaning sequence. This cleaning sequence may be conducted automatically after it has been started by the user.

[0196] Alternatively, the signal may be a signal registered in the controller and which registered signal makes the controller to initiate an automatic cleaning sequence.

[0197] The cleaning sequence may comprise a process for periodically increasing cylinder oil consumption to flush out combustion residues and wear particles based on a continuously monitoring showing the actual need.

[0198] The cleaning sequence - whether it is manually initiated by the user or automatically initiated by the controller - may also be based on prior art techniques, for example the Hans Jensen Lubricators’ so-called "automatic cleaning sequence".

[0199] The measuring of the rotation of the piston rings may for example be based on the teaching of GB214922 or the teaching of any of the above-mentioned sources mentioning monitoring and determining of rotation of a piston ring.

[0200] The automatic cleaning sequence may for example be based on the teaching of WO 2023 / 088526 owned by the same applicant.

[0201] For example, the injectors comprise a nozzle with a nozzle aperture that has a diameter D if the nozzle is circular, or wherein the nozzle has an equivalent diameter D which is two times the square root of the nozzle aperture area divided by pi if the nozzle is not circular; wherein the diameter D is at least 0.1 mm, and are configured for ejecting a spray of atomized droplets, which is also called a mist of oil. When injecting the lubricant oil a cavitation is obtained in the lubricant oil. A spray of atomized droplets is important in SIP lubrication, where the sprays of lubricant are repeatedly injected by the injectors into the scavenging air inside the cylinder prior to the piston passing the injectors in its movement towards the TDC. In the scavenging air, the atomized droplets are diffused and distributed onto the cylinder wall, as they are transported in a direction towards the TDC due to a swirling motion of the scavenging air towards the TDC. The atomization of the spray is due to highly pressurized lubricant in the lubricant injector at the nozzle. The pressure is higher than 10 bar, typically between 25 bar and 100 bar for this high-pressure injection. An example is an interval of between 30 and 80 bar, optionally between 35 and 60 bar. The injection time is short, typically in the order of 5-30 milliseconds (msec). However, the injection time can be adjusted to 1 msec or even less than 1 msec, for example down to 0.1 msec. Therefore, imprecisions of only a few msec may alter the injection profile detrimentally, why high precision is required, as already mentioned above, for example a precision of 0.1 msec.

[0202] SHORT DESCRIPTION OF THE DRAWINGS

[0203] The invention will be explained in more detail with reference to the drawing, where Fig. 1 is a sketch of part of a cylinder in a first embodiment of an engine according to the present invention,

[0204] Fig. 2 is a drawing of an embodiment of the injector illustrated in Fig. 1,

[0205] Fig. 3a is a sketch of a first embodiment of a controller illustrated in Fig. 1 in greater details,

[0206] Fig. 3b is a sketch of a second embodiment of a controller illustrated in Fig. 1 in greater details,

[0207] Fig. 4 is a sketch illustrating a further embodiment of a nozzle for the injector illustrated in Fig. 2,

[0208] Fig. 5 is a sketch corresponding to Fig. 1 of part of a cylinder in a further embodiment of an engine according to the present invention,

[0209] Fig. 6 is a sketch of an embodiment of the injector illustrated in Fig. 5,

[0210] Fig. 7 is an enlarged section of the inlet-valve housing of the injector illustrated in Fig- 6, Fig. 8 is a sketch corresponding to Fig. 1 of part of a cylinder in a further embodiment of an engine according to the present invention,

[0211] Fig. 9 is a sketch through a cylinder liner in a further embodiment of an engine according to the present invention and with a piston having piston rings and with an electric sensor arranged in the engine,

[0212] Fig. 10 is a section through one of the piston rings illustrated in Fig. 9,

[0213] Fig. 11 is a fragmented developed view of the piston ring shown if Figs. 9 and 10, Fig. 12 a schematic view of a system for tracing of piston ring rotation, Fig. 13 illustrates the effect of ship motion on top ring rotation, and

[0214] Fig. 14 illustrates a schematic view of a cylinder in an engine according to the present invention.

[0215] DETAILED DESCRIPTION / PREFERRED EMBODIMENT

[0216] Figs. 1-8 are known from WO 2023 / 088526, however being modified by adding detectors 220 for measuring the rotation of at least one of the piston rings.

[0217] In Fig. 1 is illustrated a layout of a system according to the invention in principle. In Fig. 1, only the elements necessary for understanding the invention are shown. More elements will be needed in an actual system.

[0218] FIG. 1 illustrates one half of a cylinder 1 of a large slow-running two-stroke engine, for example marine diesel engine. The cylinder 1 comprises a cylinder liner 2 on the inner side of the cylinder wall 3. Inside the cylinder wall 3, there are provided a plurality of injectors 4 for injection of lubricant into the cylinder 1. As illustrated, the injectors 4 are distributed along a circle with the same angular distance between adjacent injectors 4, although this is not strictly necessary. Also, the arrangement along a circle is not necessary, seeing that an arrangement with axially shifted injectors is also possible, for example every second injector shifted towards the piston’s top dead centre (TDC) relatively to a neighbouring injector. Each of the injectors 4 has a nozzle 5 with a nozzle aperture 5’ from which a fine atomized spray 8 with miniature droplets 7 is ejected under high pressure into the cylinder 1.

[0219] For example, the nozzle aperture 5’ has a diameter of between 0.1 and 0.8 mm, such as between 0.2 and 0.5 mm, which at a pressure of 10-100 bars, for example 25 to 100 bars, optionally 30 to 80 bars or even 50 to 80 bars, atomizes the lubricant into a fine spray 8, which is in contrast to a compact jet of lubricant. The swirl 14 of the scavenging air in the cylinder 1 transports and presses the spray 8 against the cylinder liner 2 such that an even distribution of lubrication oil on the cylinder liner 2 is achieved. This lubrication system is known in the field as Swirl Injection Principle, SIP.

[0220] However, also other principles are envisaged in connection with the improved lubrication system, for example injectors that have jets directed towards the cylinder liner.

[0221] Optionally, the cylinder liner 2 is provided with free outs 6 for providing adequate space for the spray 8 or jet from the injector 4.

[0222] In addition to the lubricant feed conduit 9, the injectors 4 are connected to the controller 11 by a pressure-control conduit 10. The lubricant feed conduit 9 is used for providing lubricant for injection. The pressure-control conduit 10 provides oil at high pressure to activate an internal pumping system inside the injector 4, which will be explained in more detail in the following.

[0223] The pressure in the pressure-control conduit 10 is higher than the pressure in the lubricant feed conduit 9. Typically, the lubricant pressure in the lubricant feed conduit 9 is in the range of 1-15 bar, for example in the range of 5-15 bar, and the oil pressure in the pressure-control conduit 10 is in the range 20-100 bar, for example in the range 30-80 bar, optionally 50-80 bar.

[0224] The controller 11 is connected to a supply conduit 12 for receiving lubricant from a lubricant supply 25, including an oil pump, and a return conduit 13 for return of lubricant, typically to an oil reservoir, optionally for recirculation of lubricant. The lubricant pressure in the supply conduit 12 is higher than the pressure in the return conduit 13, for example at least two times higher.

[0225] The controller 11 supplies lubrication oil to the injectors 4 in precisely timed pulses, synchronised with the piston motion in the cylinder 1 of the engine. For example, for the synchronisation, the controller system 11 is electronically by wires or wireless connected to a computer 11’ which controls components in the controller 11 for the lubrication supply. Potentially, the computer 11’ is part of the controller 11, for example provided inside a single casing with the other components of the controller 11. Optionally, the computer monitors parameters for the actual state and motion of the engine, for example speed, load, and position of the crankshaft, the latter revealing the position of the pistons in the cylinders.

[0226] FIG. 2 illustrates an injector 4, and FIGs. 3a and 3b illustrate some potential embodiments of the controller 11 in greater detail. The dimensions are not to scale.

[0227] The injector 4 comprises an injector housing 4’ with an injector base 21 having a lubricant inlet port 4A for receiving lubricant from the lubricant feed conduit 9 and a pressure port 4B connected to the pressure-control conduit 10 for causing ejection of lubricant by the injector 4.

[0228] A flow chamber 16, as part of the injector housing 4’, holds the nozzle 5 relatively to the injector base 21. In the shown embodiment, the flow chamber 16 is provided as a hollow rigid rod. The flow chamber 16 is sealed against the injector base 21 by an Ciring 22 and held tightly against the injector base 21. A conduit 16’ is provided as a hollow channel inside the flow chamber 16 from the rear to the front of the flow chamber 16. The conduit 16’ communicates with the lubricant inlet port 4A and with the nozzle 5 through a rear chamber 16 A, a first intermediate chamber 16B, a second intermediate chamber 16C, and front chamber 16D.

[0229] The injector 4 also comprises an outlet-valve system 15 for regulating the lubricant that is dispensed through the nozzle aperture 5’. Only if the pressure exceeds a predetermined pressure at the outlet-valve system 15, the outlet-valve system 15 opens for ejection of the lubricant into the cylinder 1 of the engine. In the embodiment of FIG. 2, the outlet-valve system 15 is exemplified as being part of the nozzle 5, although, this is not strictly necessary.

[0230] The outlet- valve system 15 comprises an outlet non-return outlet-valve 17. In the outlet non-return outlet-valve 17, an outlet-valve member 18, exemplified as a ball, is prestressed by a spring-load against an outlet-valve seat 19 by an outlet-valve spring 20. Upon provision of pressurised lubricant in the front chamber 16D, the pre-stressed force of the outlet-valve spring 20 is counteracted by the lubricant pressure, and when the pressure gets higher than the spring force, the outlet-valve member 18 is displaced from its outlet-valve seat 19, and the outlet non-return outlet-valve 17 opens for injection of lubricant through the nozzle aperture 5’ into the cylinder 1.

[0231] As exemplified, the outlet-valve spring 20 acts on the valve member 18 in a direction away from the nozzle aperture 5’. However, the configuration could be different with respect to the direction of the force of the outlet-valve spring 20 on the outlet-valve member 18 relatively to the nozzle aperture 5’, as long as the non-return outlet-valve 17 is closing for the supply of lubricant to the nozzle aperture 5’ when in an idle state between injection phases. The closing of the non-return outlet-valve 17 in an idle state prevents unintended flow of lubricant from the front chamber 16D through the nozzle aperture 5’ into the cylinder 1 between injection phases.

[0232] The rear chamber 16A communicates with the inlet port 4 A for receiving lubricant from the lubricant feed conduit 9. The rear chamber 16A communicates with the first intermediate chamber 16B through rear channel 23 A. The first intermediate chamber 16B communicates with the second intermediate chamber 16C through intermediate channel 23B, which is a cylindrical opening around an actuator-member 28, which will be explained below. The second intermediate chamber 16C communicates with the front chamber 16D through front channel 23 C.

[0233] For sake of convenience, the term “forward motion” is used for motion towards the nozzle aperture 5’ and the oppositely directed motion away from the nozzle aperture 5’ is called “rearward motion”. The front chamber 16D is emptied through the nozzle aperture 5’ by forward motion of a reciprocal plunger-member 29, which is spring-loaded against the forward motion by a helical plunger spring 29B in the second intermediate chamber 16C. The plungermember 29 comprises a channel inlet 24 that leads into front channel 23C, which is an internal channel in the plunger-member 29, for example centrally in the plunger-member 29, as indicated. During forward motion of the plunger-member 29, the front channel 23C is closed by a non-retum plunger-valve 26. In the shown embodiment, the nonreturn plunger-valve 26 is exemplified as comprising a plunger-valve ball 26A in a plunger-valve seat 26B, against which the plunger-valve ball 26A is pre-stressed by a plunger-valve spring 26C.

[0234] Forward motion of the plunger-member 29 is achieved by forward motion of an actuator-member 28, which presses against the head 29A of the plunger-member 29. The actuator-member 28 is pre-stressed in a rearward direction by a helical actuator-spring 28 A in the first intermediate chamber 16B.

[0235] In this illustrated exemplary embodiment, the actuator-member 28 and the plungermember 29 are separate elements, however, they could also be combined as a single actuator-plunger, for example by having the actuator-member 28 at one end of the single element and the plunger-member 29 at the opposite end.

[0236] Forward motion of the actuator-member 28 is achieved by pressurized lubricant from the pressure-control port 4B, which presses on the rear part 28B of the actuator-member 28 in pressure chamber 27 so that they move together.

[0237] The functioning of the injector 4 is explained in the following in greater detail. When the pressure-control port 4B is provided with pressurized oil, for example in the pressure range of 20-100 bar, the pressurized oil expands the volume of the pressure chamber 27 by pushing on the rear part 28B of the actuator-member 28 and moving the actuatormember 28 forward. As the actuator-member 28 presses against the head 29A of the plunger-member 29, the plunger-member 29 moves forward together with the actuatormember 28 against the force of the actuator-spring 28 A and the plunger spring 29B. The forward motion of the plunger-member acts on the lubricant in the front chamber 16D. As the non-return valve 26 prevents the lubricant in the front chamber 16D from escaping backwards, the lubricant in the front chamber 16D is pressurised to the predetermined pressure limit at which the outlet-valve- system system 15 with the non-return outlet-valve 17 opens for ejection of the lubricant from the front chamber 16D through the nozzle aperture 5’ into the cylinder 1.

[0238] At the end of the injection phase, the oil at the pressure-control port 4B is drained, which causes the actuator-spring 28A and the plunger spring 29B to press back the actuatormember 28 and the plunger-member 29 in a direction away from the nozzle 5. The rearward motion of the plunger-member 29 reduces the pressure in the front chamber 16D, which, in turn, closes the non-retum outlet-valve 17 and draws lubricant from the second intermediate chamber 16C through front channel 23 C into the front chamber 16D, as the plunger non-retum valve 26 is opened by the pressure reduction in the front chamber 16D. This way, the non-retum plunger-valve 26 acts as a suction valve because the pressure reduction in the front chamber 16D causes refilling of the front chamber 16D with lubricant by suction through the non-retum plunger-valve 26. During this returning motion of the actuator-member 28 and plunger-member 29, lubricant in the second intermediate chamber 16C is replenished from the first intermediate chamber 16B, which is turn is filled by lubricant from the rear chamber 16A that received the lubricant through the lubricant inlet port 4A.

[0239] For proper functioning, the lubricant inlet port 4a is provided with lubricant from the lubricant feed conduit 9 at a constant pressure, and the pressure-control port 4B is provided with pressure-oil from the pressure-control conduit 10 intermittently for each injection-cycle. The pressure at the pressure-control port 4B is raised in the injection phase and reduced in the idle state between injection phases.

[0240] If the forward force on the actuator-member 28 by the oil pressure in the pressure chamber 27 in the idle state is less than the combined rearward forces from the actuator spring 28A and the plunger spring 29B, the actuator-member 28 and the plunger-member 29 are returned fully to their most rearward possible position, which is the one indicated in FIG. 2. Thus, a full stroke of the plunger-member is achieved by intermittently changing the oil pressure at the pressure-control port 4B between a full pressure and a lower pressure, for example at the pressure of the lubricant in the lubricant supply line 9 or even lower. However, the actuator-member 28 and the plunger-member 29 can be held offset from the most rearward position by adjusting the pressure at the pressure-control port 4B and in the pressure chamber 27 at an offset pressure level that creates a force on the actuator such that the springs 28A and 29B do not fully elongate during rearward motion of the actuator-member 28 and the plunger-member 29 but are kept slightly compressed. This is possible because the force of the springs 28A and 29B is varying in dependence on the compression length, largely following a linear dependence on the displacement of the actuator-member from the most rearward position. The offset pressure level is smaller than the pressure level necessary to cause the non-return outlet-valve 17 to open for injection.

[0241] In principle, the injector 4 can be provided with lubricant at the inlet port 4 A from one lubricant source and with pressure-oil or other pressure-liquid from an entirely different source. However, typically, for sake of simplification and convenience, the pressure-oil at the pressure-control port 4B is provided from the same source as the lubricant at the inlet port 4A, however, with increased pressure, for example by use of a pressure intensifier.

[0242] An illustrative example of how the intermittent pressure change at the pressure-control port 4B is achieved is explained in the following with reference to the controller 11, which is illustrated in FIG. 3a and in an alternative embodiment in FIG. 3b. It is pointed out however, that the controllers in FIGs. 3a and 3b are only exemplified embodiments, and the injector of FIG. 2 is independent of the illustrated controller 11 of FIGs. 3 and 4 and can function with other types of controllers.

[0243] In the example of FIG. 3a, the controller 11 comprises a toggle valve 30 that has a toggle-valve inlet port 30A, which is connected to the supply conduit 12, a toggle-valve outlet port 30B, which is connected to the pressure-control conduit 10 for communication with the injector’s pressure-control port 4B, and a toggle-valve return port 30C, which is connected to the return conduit 13. Between the toggle-valve return port 30C and the return conduit 13, there is illustrated a pressure-control valve 31, which is explained in greater detail below, and which is optional. The toggle-valve 30 comprises a first toggle closure element 32A and a second toggle closure element 32B, which are arranged rigidly connected and reciprocal between a first state, where the toggle-valve inlet port 30A and the toggle-valve outlet port 3 OB are communicating, and a second state, where the toggle-valve outlet port 3 OB and the toggle-valve return port 30C are communicating. The reciprocal movement is illustrated by arrow 33. In FIGs. 3a and 3b, only the second state is illustrated. For example, the toggle-valve 30 is a three-way valve, as illustrated, potentially a magnetic valve.

[0244] In the injection phase, the toggle-valve 30 is in the first state, where the highly-pressurised lubricant from the supply conduit 12 is supplied to the pressure-control port 4B of the injector 4 in order to press the actuator-member 29 forward to cause injection of lubricant into the cylinder 1. At the end of the injection phase, the toggle member 30 is moved to the second state, as illustrated, and the lubricant from the pressure-control port 4B is drained through the toggle valve 30, out of the toggle-valve return port 30C into the return line 13, which allows the actuator-member 28 and the plunger-member 29 to return back to the idle state. For example, the toggling of the toggle-member 32 is controlled in cooperation with the computer 11’.

[0245] As the injector 4 comprises a pumping system upstream of the nozzle 5, namely the plunger-member 29, the lubricant supplied for injection does not need to be provided at high pressure in the feed conduit 9. Therefore, the pressure of the return conduit 13, typically in the range of 5-15 bar, is sufficient for supplying lubricant through the feed conduit 9 to the inlet port 4A of the injector 4.

[0246] An optional injection volume-adjustment mechanism is also illustrated in FIG. 2 in combination with FIGs. 3a and 3b. In this embodiment, a pressure-valve 31 is provided with a pressure-valve inlet port 31 A, connected to the toggle-valve return port 30C, and a pressure-valve outlet port 3 IB, connected to the return conduit 13. This implies that the toggle-valve return port 3 IB is connected to the return conduit 13 only through the pressure-valve 31, which is used to adjust the return pressure at the toggle-valve return port 30C.

[0247] In the exemplified embodiment, the pressure-valve 31 comprises a spring-loaded pressure adjustment member 31C, the pre-tension of which is adjustable by a pre-tensioner 3 ID, for example a screw, as illustrated. Although, it is possible to configure the pretensioner for manual adjustment, typically, the pre-tensioner is adjusted by a motor or other type of actuator. The adjustment of the pre-tensioner causes more or less pretension on the spring-loaded pressure adjustment member 31C, such that the back-pressure at the pressure-valve inlet port 31A and at the toggle-valve return port 30C is adjusted by this pre-tension.

[0248] The adjusted back pressure at the toggle-valve return port 30C determines the lowest pressure at the pressure-control port 4B. Increasing this back-pressure offsets the actuator-member 28 and the plunger-member 29 from the most rearward position. As the next injection phase starts the forward motion from this offset position, the stroke of the plunger-member 29 is shorter that it would be when starting from the most rearward position. Thus, by adjusting the back-pressure by the pressure-valve 31, the stroke of the injector 4 is precisely regulated, and correspondingly the amount of the lubricant that is injected into the cylinder 1. In FIG. 2, the most rearward position of the actuatormember 28 and the plunger-member 29 is indicated.

[0249] Typically, there is provided one toggle-valve 30 for a group of injectors, for example all injectors of a cylinder. However, in an alternative embodiment, there is provided one toggle-valve 30 for each injector 4. In case that the optional pressure-valve 31 is included in the system in order to adjust the stroke of the plunger-member 29 and the injection volume, it is, typically, provided for a group of injectors 4. However, it is also possible to provide one pressure-valve 31 for each injector 4.

[0250] As it appears from the above example, the lubricant feed conduit 9 is communicating with the return line 13. In the illustration of FIG. 3a, the return conduit 13 is entering the controller 11, and the feed conduit 9” is exiting the controller 11. This is also illustrated in FIG. 1 by the solid line 9” which in extension is connected to the feed conduit 9. In case of the controller 11 being an add-on unit, the controller 11 would have at least

[0251] 4 conduit connectors.

[0252] However, this need not be so. Optionally, the controller 11 comprises a return exit line 34 which is connected to the return conduit 13, as illustrated in FIG.3b. In the latter case, the return conduit 13 is directly communicating with the feed conduit 9’ and 9. This embodiment is illustrated in FIG. 1 by the dotted alternative line 9’, which in extension is connected to the feed conduit 9. In this case, the return conduit 13 in extension of the feed conduit 9 and 9’ provides lubricant directly to the lubricant inlet port 4 A of the injectors 4 for injection into the cylinder, and the controller 11 is bypassed. FIG. 4 illustrates a second, alternative embodiment of an outlet-valve system 15. The generalised principle of the outlet- valve system 15 is similar to the one disclosed in WO2014 / 048438. This reference also provides additional technical details as well as explanations to the functioning of the injector presented here, which are not repeated here, for convenience. A nozzle aperture 5’ is provided in the nozzle 5 tip for ejection of lubrication oil. Inside a cavity 40 of the nozzle 5, an outlet-valve member 18 is provided, the outlet-valve member 18 comprising a stem 41 and a cylindrical sealing head 42 which is arranged slidingly in a cylindrical cavity part 43 at the nozzle tip 44. The position of the valve member 18 is pre-stressed backwards away from the nozzle tip 44 by a spring 45 and is offset forwards by oil pressure acting through a channel 46 upon the back part 47 of the stem 41, the oil pressure acting against the spring force. The nozzle aperture 5’ is sealingly covered by the sealing head 42 which abuts the cylindrical cavity part 43 at the nozzle tip 44, unless the valve member 18 is pushed forward such that the sealing head 43 slides pass and away from the nozzle aperture 5’ to allow lubricant oil to flow from the inner cavity 46 through the nozzle aperture 5’ for ejection.

[0253] The following values are non-limiting illustrative examples of possible working pressures. The pressure in the return conduit 13 and the feed conduit 9 is 10 bar. The pressure in the supply conduit 12 is 40 bars. The outlet-valve 15 opens at 37 bar, such that the lubricant is injected at 37 bars. The springs 28 A and 29B are configured for pressing the plunger-member 29 and the actuator-member 28 fully back to the rearmost position if the pressure at the pressure-control port 4B in the idle state between injection phases is 10 bar. The pressure-valve is adjustable to a pressure of between 10 and 30 bars, for example 20 bar, well below the 37 bar injection pressure but high enough to provide high enough pressure in the pressure chamber 27 for the actuator-member 28 not returning fully to the most rearward position but keeping a distance from the most rearward. By adjusting this distance through adjustment of the pressure in the range of 10- 30 bar, the injection volume in the front chamber 16D is adjusted, because the forward motion in the injection phase is smaller the more the plunger-member 29 is offset from the most rearward position at the start of the injection phase. Optionally the injection volume is controlled by a flowmeter inserted in the feed line 9, either for the group of injectors or for each single injector 4. The flowmeter measures flow (mass and / or volume) and is then used for control that the inj ector(s) is / are properly working.

[0254] The injection system with the injector 4 as described above and the controller 11 are simple to install and replace. It is a relatively low-cost technical solution, albeit robust and stable. Especially, the injection volume is precisely adjustable. Also, the system does not comprise electrical wires to and from the injector 4, which makes it robust against heat, whereas electrical wires are likely to have an insulation layer that melts in heat.

[0255] The above-described embodiments are known from WO 2019 / 114905. However, the engine differs as it comprises a flowmeter 35. The flowmeter shall be used for measuring the lubricant flow in the lubricant feed conduit 9.

[0256] The signal from the flowmeter for the actual flow is then transformed in the controller into an actual amount. The calculated actual amount is compared to the desired value, and the controller then controls the injectors and adjust the setting thereof in order to regulate the amount to the desired value for lubricant amount to be injected for a specific operation mode.

[0257] FIG. 5 illustrates one half of a cylinder 1 of a large slow-running two-stroke engine, for example marine diesel engine. The cylinder 1 comprises a cylinder liner 2 on the inner side of the cylinder wall 3. Inside the cylinder wall 3, there are provided a plurality of injectors 4 for injection of lubricant into the cylinder 1. As illustrated, the injectors 4 are distributed along a circle with the same angular distance between adjacent injectors 4, although this is not strictly necessary. Also, the arrangement along a circle is not necessary, seeing that an arrangement with axially shifted injectors is also possible, for example every second injector shifted towards the piston’s top dead centre (TDC) relatively to a neighbouring injector.

[0258] Each of the injectors 4 has a nozzle 5 with a nozzle aperture 5’ from which a fine atomized spray 8 is ejected under high pressure into the cylinder 1. For example, the nozzle aperture 5’ has a diameter of between 0.1 and 0.8 mm, such as between 0.2 and 0.5 mm, which at a pressure of 10-100 bars, for example 25 to 100 bars, optionally 30 to 80 bars or even 50 to 80 bars, atomizes the lubricant into a fine spray 8, which is in contrast to a compact jet of lubricant. The swirl 14 of the scavenging air in the cylinder 1 transports and presses the spray 8 against the cylinder liner 2 such that an even distribution of lubrication oil on the cylinder liner 2 is achieved. This lubrication system is known in the field as Swirl Injection Principle, SIP.

[0259] However, also other principles are envisaged in connection with the improved lubrication system, for example injectors that have jets directed towards the cylinder liner.

[0260] Optionally, the cylinder liner 2 is provided with free outs 6 for providing adequate space for the spray 8 or jet from the injector 4.

[0261] The injectors 4 receive lubrication oil through a feed conduit 9, typically through a common feed conduit 9, from a lubricant supply 25, for example oil circuit, of the engine including a potential lubricant pump that raises the pressure of the lubricant to an adequate level. For example, the pressure in the feed conduit 9 is in the range of 25 to 100 bars, optionally 30 to 80 bars, which is a typical range of pressure for SIP injectors.

[0262] The injectors 4 are provided with electrical connectors 110’ that are electrically communicating with a controller 11 through electrical cables 110. As mentioned earlier the injectors may alternatively be wireless communicating with the controller 11. The controller 11 sends electrical control signals to the injectors 4 for controlling injection of lubricant by the injector 4 through the nozzle 5. As it is illustrated, one cable 110 is provided for each injector 4, which allows individual control of injection by the respective injector. However, it is also possible to provide one electrical cable 110 from the controller 11 to all injectors 4 such that all injectors 4 are injecting simultaneously upon receiving an electrical control signal through one single electrical cable. Alternatively, it is also possible to provide one electrical cable 110 from the controller 11 to a subgroup of injectors, for example a subgroup of 2, 3, 4, 5 or 6 injectors, such that a first subgroup is controlled by the controller through a first cable 10 and a second subgroup is controlled through a second cable 110. The number of cables and subgroups are selective dependent on preferred configurations. A flowmeter 35 is connected with the lubricant feed conduit 9 and the electrical cables 110 and is arranged for measuring the lubricant flow to each injector 4 or to each subgroup of injectors.

[0263] The electrical control signals from the controller 11 to the injectors 4 are provided in precisely timed pulses, synchronised with the piston motion in the cylinder 1 of the engine. For example, for the synchronisation, the controller system 11 comprises a computer 11’ or is electronically connected a computer 11’, by wires or wireless, where the computer 11 ’ monitors parameters for the actual state and motion of the engine, for example speed, load, and position of the crankshaft, where the latter reveals the position of the pistons in the cylinders.

[0264] The above-described embodiment is known from WO 2019 / 114903. However, the engine differs as it comprises the flowmeter 35. The flowmeter shall be used for measuring the lubricant flow in the lubricant feed conduit 9.

[0265] Fig. 6 illustrates principal sketches of an injector 4. Fig. 6 is an overview sketch with three different views of the exemplified injector, top view, end view and cross-sectional side view.

[0266] The injector 4 comprises a lubricant inlet port 112 for receiving lubricant from the lubricant feed conduit 9. The inlet port 112 is provided in an inlet-valve housing 121 comprising an inlet-valve system 113 communicating with the inlet port 112 for regulating the amount of lubricant received from the lubricant feed conduit 9 during a lubrication phase. The injector 4 also comprising an outlet-valve system 115 for regulating the lubricant that is dispensed through the nozzle aperture 5’. A rigid flow chamber 116 connects the inlet-valve system 113 with the outlet-valve system 115 for flow of lubricant to the nozzle 5. In the shown embodiment, the flow chamber 116 is provided as a hollow rigid rod. The flow chamber 116 is sealed against the inlet-valve housing 121 of the inlet-valve system 113 by an O-ring 122 and held tightly against the inlet-valve housing 121 by a flange 123 that is bolted by bolts 124 against the inlet-valve housing 121.

[0267] Fig. 7 is an enlarged portion of the inlet-valve system. Fig. 7 illustrates the inlet-valve system 113 in greater detail. Inside the inlet-valve housing 121, a non-return inlet-valve 125 is provided with an inlet-valve member 126 that is pre-stressed against an inlet-valve seat 127 by an inlet-valve spring 128. The inletvalve member 126 is exemplified as a ball, however, a different shape, for example oval, conical, plane, or cylindrical, would also work. When the inlet-valve member 126 is displaced from the inlet-valve seat 127 against the force of the inlet-valve spring 128, lubricant flows from the inlet port 112 along the inlet-valve spring 128, passes the inletvalve member 126 and the inlet-valve seat 127, and enters a channel 129 on an opposite side of the inlet-valve member 126. From the channel 129, the lubricant flows through passage 130 and enters the hollow part 116’ of the flow chamber 116, for flow to an outlet-valve system, which have a generalised principle similar to the one disclosed in WO2014 / 048438. This reference also provides additional technical details as well as explanations to the functioning of the injector presented here, which are not repeated here, for convenience.

[0268] In order to displace the inlet-valve member 126 (ball), a push-member 131, exemplified as a push-rod, is provided reciprocal in the channel 129. The push-member 131 is not fastened to the inlet-valve member 126 but is fastened to a reciprocal solenoid-plunger 133 that is driven by a solenoid coil 132. The solenoid-plunger 133 is retracted by a plunger spring 134 when in idle condition. When the solenoid coil 132 is excited by electrical current, the solenoid-plunger 133 is moved forward against the force of the plunger spring 134 until it comes to a halt against a plunger stop 135. Due to the movement of the solenoid-plunger 133, the push-member (push-rod) 131 pushes the inletvalve member (ball) 126 away from the inlet-valve seat 127, allowing lubricant to flow through the inlet non-return valve 125 and into the flow chamber 116.

[0269] In advantageous embodiments, the push-member (push-rod) 131 is withdrawn a distance from the inlet-valve member (ball) 126 when in idle state, such that there is a free range distance in between the push-member 131 and the inlet-valve member 126. When the solenoid coil 132 is excited, the push-member 131 is accelerated by the solenoid coil 132 over the free-range distance before it impacts the inlet-valve member 126 after initial acceleration. This results in the inlet-valve member 126 being displaced abruptly from the inlet-valve seat 127, as compared to a situation where the inlet-valve member 126 moves together with push-member 131 during the first part of the acceleration. The quick displacement of the inlet-valve member 126, in turn, is advantageous for a precise timing of the start of the lubricant injection into the cylinder 1. Optionally, the free- range distance is adjustable by an adjustment screw 136 at the end of the solenoidplunger 133.

[0270] After the injection phase, the lubricant supply from the inlet port 112 to the nozzle 5 is stopped by cutting the current to the solenoid coil 132, which results in the solenoidplunger 133 being pushed back by the plunger spring 134, and the inlet-valve member 126 returns to the tight inlet-valve seat 127 for an idle phase in the injection cycle.

[0271] The amount of lubricant oil is controlled by the flowmeter and the controller / computer makes it possible to regulate the lubricant amount and to effect calibration of the injectors.

[0272] Fig. 8 corresponds to Figs. 1 and illustrates a further embodiment of one half of a cylinder 1 of a large slow-running two-stroke engine, for example marine diesel engine. This embodiment comprises oil injectors, the injectors 4 may be HJ Smartlube 4.0 E- injectors. The injectors 4 are connected with a cylinder-manifold with flowmeter 203. The cylinder-manifold with flowmeter is connected with a controller 11 via a communication line 211 for flowmeter feedback signals. The controller 11 may be a local cylinder controller which is connected with a central controller 208 via a communication line 210.

[0273] The cylinder-manifold with flowmeter 203 is connected with a pump unit 205. The pump unit 205 is via the supply conduit 12 connected with the lubricant supply 25.

[0274] The pump unit 205 is via a pressurized oil feed line 214 connected to cylinder manifolds (common rail) for providing lubricant oil to the injectors 4.

[0275] An injector signal bus 212 connects the controller 11 with the injector for regulating the lubricant amount and to effect calibration of the injectors.

[0276] In Figs. 1, 5 and 8 a detector 220 is illustrated. The detector 220 is connected with a transmission line 221 for sending a signal for the rotation of a piston ring to the controller 11. In Figs. 1, 5 and 8 there is not disclosed a piston in the cylinder 1. However, a piston corresponding to the piston 215 disclosed in Fig. 9 will be provided in the cylinder 1 which piston will be provided with piston rings corresponding to the piston rings 216 disclosed in Fig. 9.

[0277] The signal for the rotation of the piston ring 216 may represent the rotational position or the rotational speed of the piston ring 216. In the embodiments illustrated in Figs. 1, 5 and 8 the transmission line is a wirelessly transmission line 221 but may alternatively be an electronically transmission line.

[0278] Possible detectors 220 will be explained below.

[0279] Fig. 9 is a diagrammatic sectioned view showing a cylinder liner 2 of a large diesel engine, in this case a marine diesel engine. Moving in the liner 2 is a piston 215 which is connected by a piston rod 215’, a crosshead (not shown) and a connecting rod to the engine crankshaft. Carried in grooves in the piston 215 near the top thereof are piston rings 216 each formed with a conventional gap 217. The piston rings 216 have an axis A which substantially coincides with the axis of the piston and with the axis of the cylinder liner. The liner 2 has a wall 218 on which the piston 215 moves and against which the piston rings 216 are pressed by their own resilience and by the gas forces occurring in operation.

[0280] As can also be seen in Fig. 9, the liner 1 has a passage 219 receiving a detector 220 for measuring the rotation of at least one of the piston rings. In the actual embodiment the detector is provided in form of an electromagnetic proximity detector 220. The detector 220 is connected with a transmission line 221 for sending a signal for the rotation to the controller 11 (explained above), which transmission line is an electronically or wirelessly transmission line 221. In the actual embodiment the line 221 is alternatively illustrated as being connected to some form of monitoring facility 222, such as an oscilloscope.

[0281] One of the piston rings 216 is shown in greater detail in Figs. 10 and 11. The piston ring 216 has a rectangular cross section 223 formed with a triangular groove 224 which narrows with increasing distance from the rubbing surface 229 of the piston ring. The groove 224 receives an insert 225 of a non-magnetizable substance, preferably bronze. The depth T of the groove 224 — i.e., of the insert 225 — is larger than the permissible amount of wear of the piston ring 216. When new the groove 224 has a width B at the rubbing surface 229. After wear of the piston ring the width of the groove 224 will decrease to a smaller width B and the depth of the groove 224 will decrease to a smaller depth T. Accordingly, signals from the detector 220 may also be used for determining the amount of piston ring wear as explained in GB214922.

[0282] Referring to Fig. 11, which is a developed view of the rubbing surface 229 of the piston ring 216, it can be seen that the groove 224 with the insert 225 extends helically from one end 226 to the other end 227 of the piston ring 216. The ring gap 217 is disposed between the ends 226 and 227 of the piston ring 216 which form the sides of the gap 217.

[0283] The groove 224 with the specific pattern disposed around the periphery of the piston ring gives a characteristic axial magnetic pattern for each angular position around the piston ring. This pattern is adapted to be recognized by the detector 220 located adjacent the surface of the cylinder wall 218 engaged by the piston ring whereby the angular position of the ring relative to the wall may be determined.

[0284] The helically extending groove is very simple construction as not only changes in rotational positions of the piston ring can be detected but also the actual rotational position of the piston ring can be accurately determined. The triangular groove means that the width of the groove differs at different depths so that as the piston ring wears the width of the mouth of the groove will change and such change will be detectable by the detector 220 and will also be visible on dismantling of the piston. When this feature is combined with an ability to determine the rotational position of the piston ring during operation, it is also possible to determine the wear of the piston ring 216 at different places around its entire periphery.

[0285] Fig. 12 discloses an alternative example of a system for tracing of piston ring rotation. In the example illustrated to piston rings 216 is used. The piston ring 216 has a gap 217 between the two ends 226 and 227. Moreover, a radiotracer 228 is provided in each of the two the piston ring 216. The radiotracers are different whereby it is possible to trace two piston rings at the same time. Alternatively, the radiotracer 228 may only be provided in one piston ring or more piston rings may be provided with radiotracers 228.

[0286] Three detectors 220 are illustrated which trough transmission lines 221 are connected with a controller 11 and a computer 11’. The movement of two piston rings are traced with three detectors 220. In this embodiment the detectors 220 are provided in form of ratemeters 220 having two windows (upper and lower). The windows are set to count different gamma radiation from the radiotracers 228. Two kinds of radiotracers in form of radioisotopes are used for identification of the two different piston rings 216.

[0287] The system may be operated as teached by Sunghee Jung and Joonha Jin, Korea atomic energy research institute 1999; “Monitoring of rotational movements of two piston rings in a cylinder using radiotopes”.

[0288] The system according to the present invention makes it possible to activate the cleaning sequence on the basis of the rotation of the rings independently of other parameters. However, in some examples for the system it is possible to make use of other parameters in combination with the data for the rotation. Thus, it is possible to have variable limits for rotation speed or time for standstill, based on e.g. engine load, changes in engine load, heeling, engine type, age of the rings, fuel type, cylinder oil type, cylinder oil feed rate, etc. However, such further parameters are possible parameters that can optionally be used to estimate variable limits.

[0289] The source from Stewart Moore, BP Research & Engineering Centre. CIMAC Congress 1998 Copenhagen: “The complexities of piston ring lubrication in a large two-stroke marine diesel engine” teaches a measuring of rotation of the piston ring measured on a ship compared to the ship's heeling. It shows that changes in film thickness is influenced by the motion of the ship in bad weather. Also, it has shown that if the ship rolled violently it could cause the top piston ring to rotate. The so-called SIPWA system may be used to record the rotational position of the piston ring. This system is developed to determine the average radial wear of the top piston ring in order to allow action to be taken in the event of adverse ring wear. However, this system does not teach that the cleanliness of the piston ring may be determined and accordingly there is no teaching to activate an automatic cleaning sequence.

[0290] Thus, applying the data for the rotation to determine a cleanliness of the piston rings and thus also to determine a need for cleaning by activating a cleaning sequence, may also be used in combination with comparing the ring rotation measured on a ship to the ships’s heeling. This may be effected by using the measuring principles in the SIPWA system and to use the result of the ring rotation due to movements of the ship when determining the need for cleaning by activating the cleaning sequence.

[0291] Fig. 13 illustrates the effect of ship motion on top ring rotation. This illustration is taken from: “The complexities of piston ring lubrication in a large two-stroke marine diesel engine.” By Dr. Stewart Moore, BP Research & Engineering Centre. CIMAC Congress 1998 Copenhagen.

[0292] The illustration shows that the rotation of the piston ring can be related to the ship’s movement.

[0293] One effect that became apparent very early during these measurements was that if the vessel rolled violently it could cause the top ring to rotate. Although vessel movement is clearly not the only mechanism causing rotation, as it shows that there are times when the ring rotates under extremely stable conditions, it is interesting that there is at least one operating variable that it can be related to.

[0294] An example of this motion effect is shown in Fig. 13 . The upper trace shows the angle of lay of the ship (port I starboard), recorded every 5 minutes, while the lower trace shows the rotational position of the ring recorded by the SIPWA system: both signals being recorded by a film thickness data logger. A SIPWA piston ring is divided circumferentially into 64 segments - 8 segments with 8 sub-segments in each segment - with segments zero and 64 at the ring gap. Bold vertical lines have been added to the figure to show examples of where a sudden movement to either port or starboard caused the ring to rotate. Of course, as the ring gap rotates past the SIPWA sensor, the recorded ring position jumps from 64 to zero. This is the reason for the sudden large vertical shifts on the ring rotation trace seen, for example, at 255 running hours.

[0295] It is not known why changes in vessel attitude should cause the ring to rotate, or to change the direction of rotation, but engine builders have been interested for many years in ring rotation and some have tried methods to artificially induce it to even out wear rates. This is one of the first times that ring rotation has been directly linked to an operating variable.

[0296] Fig. 14 illustrates a cylinder in an engine according to the invention. The following elements are illustrated in Fig. 14:

[0297] 2 the cylinder liner.

[0298] 4 the injector.

[0299] 8 the lubricant spray.

[0300] 215 the piston with piston rings.

[0301] 220 the detector.

[0302] 221 a signal line between the detector 220 and a piston ring monitoring controller 232.

[0303] 230 a signal line between a cylinder lubrication controller 235 and the injector 4.

[0304] 231 a signal line between a piston ring monitoring controller 232 and a cylinder lubrication controller 235.

[0305] 232 the piston ring monitoring controller.

[0306] 233 a signal line between the cylinder lubrication controller 235 and an HMI 235.

[0307] 234 the HMI for the cylinder lubrication system.

[0308] 235 the cylinder lubrication controller.

[0309] The controllers 323 and 235 will be part of the controller 11.

[0310] Fig. 14 illustrates a cylinder liner 2 with one injector 4 shown for simplicity. The cylinder liner is shown with the piston 215 in two different positions. To the left the piston 215 is moving upward and the injector 4 is spraying the lubricant spray 8 onto the wall of the cylinder liner 2. To the right the piston 215 is passing the lubrication quills and the injector 4e is spraying the lubricant spray 8 into the piston ring pack. These two, or more, injections may happen in the same engine revolution.

[0311] During the cleaning sequence the injection oil amount is increased only in the ring pack to facilitate better cleaning of the piston ring pack. The sensor 220 is mounted in the lower part of the cylinder liner 2 to monitor the position of at least one piston ring 216. This signal is sent to the controller 232 that monitors the rotation of the piston ring(s), e.g. a SIPWA system. This system sends the signal to the cylinder lubrication controller 235, which communicates with the injector 4 and the HMI 234.

[0312] With the present invention it is the first time that measurements of ring rotation linked to an operating variable is used when determining the need for cleaning and for activating the cleaning sequence.

[0313] Numbering

[0314] 1 cylinder

[0315] 2 cylinder liner

[0316] 3 cylinder wall

[0317] 4 injector

[0318] 4’ injector housing

[0319] 4 A inlet port of oil injector 4

[0320] 4B pressure-control port of oil injector 4

[0321] 5 nozzle

[0322] 5’ nozzle aperture

[0323] 6 free cut in liner

[0324] 7 atomised spray from a single injector 4

[0325] 8 swirling spray

[0326] 9 lubricant feed conduit

[0327] 10 pressure-control conduit

[0328] 11 controller

[0329] 11 ’ computer

[0330] 12 supply conduit 13 return conduit

[0331] 14 swirl in cylinder

[0332] 15 outlet-valve system of injector 4

[0333] 16 flow chamber connecting inlet-valve system 13 with outlet-valve system 15

[0334] 16’ to hollow part of flow chamber 16

[0335] 16A rear chamber

[0336] 16B first intermediate chamber

[0337] 16C second intermediate chamber

[0338] 16D front chamber

[0339] 17 non-return outlet-valve, exemplified as outlet ball valve

[0340] 18 outlet-valve member, exemplified as ball

[0341] 19 outlet-valve seat

[0342] 20 outlet-valve spring

[0343] 21 injector base

[0344] 22 O-ring at end of flow chamber 16

[0345] 23 A rear channel in actuator-member 28 connecting rear chamber 16A with first intermediate chamber 16B

[0346] 23B intermediate channel between first and second intermediate chamber 16 A, 16B

[0347] 23 C front channel in plunger-member 29 between second intermediate chamber 16B and front chamber 16D

[0348] 24 channel inlet into front channel 23 C

[0349] 25 lubricant supply

[0350] 26 non-return plunger-valve

[0351] 26A plunger-valve ball

[0352] 26B plunger-valve seat, against which the plunger-valve ball 26A is pre-stressed

[0353] 26C plunger-valve spring pre-stressing plunger-valve ball 26A against plunger-valve seat 26B

[0354] 27 pressure chamber at rear part 28B

[0355] 28 actuator-member for pushing head 29’ of plunger-member 29

[0356] 28A actuator-spring acting rearwards on actuator-member 28

[0357] 28B rear part of actuator-member 28

[0358] 29 plunger-member

[0359] 29A head of plunger-member 29

[0360] 29B plunger spring in second intermediate chamber 16C 30 toggle-valve

[0361] 30A toggle-valve inlet port

[0362] 3 OB toggle-valve outlet port

[0363] 30C toggle-valve return port

[0364] 31 pressure-valve

[0365] 31 A pressure-valve inlet port

[0366] 3 IB pressure-valve return port

[0367] 31C pressure regulator, ex. spring-loaded pressure adjustment member injection-phase

[0368] 3 ID pre-tensioner in pressure-valve 31

[0369] 32 toggle-member

[0370] 32A first toggle closure element of toggle-member 32

[0371] 32B second toggle closure element of toggle-member 32

[0372] 33 arrow illustrating reciprocal movement of toggle member 32

[0373] 34 return exit line from controller 11 to return conduit 13

[0374] 35 flowmeter

[0375] 36 desired lubricant amount

[0376] 37 calculated actual lubricant amount

[0377] 38 signal from flowmeter

[0378] 39 control signal

[0379] 40 uncalibrated injector

[0380] 41 calibrated injector

[0381] 112 lubricant inlet port of injector 4

[0382] 113 inlet-valve system of injector 4

[0383] 114 swirl in cylinder

[0384] 115 outlet-valve system of injector 4

[0385] 116 flow chamber connecting inlet-valve system 113 with outlet-valve system 115

[0386] 116’ to hollow part of flow chamber 16

[0387] 117 outlet non-return valve, exemplified as outlet ball valve

[0388] 118 outlet-valve member

[0389] 119 outlet-valve seat

[0390] 120 outlet-valve spring

[0391] 121 inlet-valve housing of inlet-valve system 115

[0392] 122 O-ring at end of flow chamber 116

[0393] 123 flange for holding flow chamber 124 bolts for holding flange 123 and flow chamber 16 against inlet-valve housing 121

[0394] 125 inlet non-return valve, exemplified as inlet ball valve

[0395] 126 inlet-valve member, exemplified as ball

[0396] 127 inlet-valve seat

[0397] 128 inlet-valve spring

[0398] 129 channel in inlet-valve system

[0399] 130 passage from channel 129 to hollow part 116’ of flow chamber 16

[0400] 131 push-member fastened to solenoid-plunger 133, push-member exemplified as rod

[0401] 132 solenoid coil

[0402] 133 solenoid-plunger in solenoid coil 131

[0403] 134 plunger spring

[0404] 135 plunger stop

[0405] 136 adjustment screw for adjustment of the free range distance

[0406] 203 cylinder manifold with flowmeter

[0407] 205 pump unit

[0408] 208 central controller

[0409] 210 communication line between local cylinder controller and central controller

[0410] 211 communication line for flowmeter feedback signals

[0411] 212 injector signal bus

[0412] 214 pressurized oil feed line

[0413] 215 piston

[0414] 215’ piston rod

[0415] 216 piston ring

[0416] 217 gap in piston ring

[0417] 218 wall of the liner

[0418] 219 passage

[0419] 220 detector

[0420] 221 line

[0421] 222 monitoring facility

[0422] 223 rectangular cross section

[0423] 224 triangular groove

[0424] 225 insert

[0425] 226 one end

[0426] 227 other end 228 radiotracer

[0427] 229 rubbing surface of piston ring

[0428] 230 signal line

[0429] 231 signal line 232 piston ring monitoring controller

[0430] 233 signal line

[0431] 234 HMI

[0432] 235 cylinder lubrication controller

Claims

CLAIMS1. A method for lubricating a large combustion engine, for example a large slow-running two-stroke engine, comprising a cylinder (1) with a liner (2) and a reciprocal piston(215) having piston rings (216) establishing contact with the liner (2) inside the cylinder (1) and with a lubrication system comprising- a lubricant supply (25),- a plurality of lubricant injectors (4) distributed along a perimeter of the cylinder (1) for injection of lubricant into the cylinder (1) at positions on the perimeter during injection phases,- a lubricant supply conduit (12) connecting the lubricant supply (25) with the lubricant injectors (4), the engine further comprising- a controller (11) for controlling the amount and timing of the lubricant injection by at least one of the lubricant injectors (4), wherein each lubricant injector (4) comprises- an inlet port (112) flow-connected to the lubricant supply conduit (12) for receiving lubricant from it,- a nozzle (5) with a nozzle aperture (5’) extending into the cylinder configured for injecting lubricant from the inlet port (112) into the cylinder (1) in the injection phase, wherein the method is characterised in that the method comprises the steps of- measuring the rotation of at least one of the piston rings (216),- sending a signal for the rotation to the controller (11),- establishing data in the controller (11) for the rotation of the at least one piston ring(216), wherein the established data comprises data for the rotational speed of the at least one piston ring (216),- applying the data for the rotation to determine a cleanliness of the piston rings (216) and thus also to determine a need for cleaning,- establishing a number of desired values for lubricant amount to be injected, typically specified as a feed rate, for specific operation mode,- storing said desired values in a database in the controller (11),- comparing in the controller (11) the calculated actual amount (37) to the desired value- controlling the injectors (4) and adjusting the setting thereof in order to obtain the desired values for lubricant amount (36) to be injected for a specific operation mode,- providing a signal that the piston ring pack needs cleaning and- activating a cleaning sequence,- which cleaning sequence comprises more parameters including timing, duration and distribution of the lubricant injection, wherein the step of activating the cleaning sequence either includes the step of- providing the signal that the piston ring pack needs cleaning to the user, for example shown in a monitoring facility and- initiating by the user the cleaning sequence which initiation is based on the provided signal that the piston ring pack needs cleaning or includes the steps of- providing the signal that the piston ring pack needs cleaning as signal registered in the controller (11) and- initiating, by the controller (11) an automatic cleaning sequence which initiation is based on the provided signal that the piston ring pack needs cleaning.

2. The method of lubricating a large combustion engine according to claim 1, wherein the method includes the step of providing for the engine- providing in the at least one piston ring (216) one or more radiotracers (228) or magnetic pattern producing devices,- detecting with a detector (220) mounted on the engine the signals from the radiotracers (228) or the magnetic pattern producing devices,- determining the location of the radiotracers (228) or the magnetic pattern producing devices relative to the cylinder (1) and thus determining the rotation of the at least one piston ring (216).

3. The method of lubricating a large combustion engine according to claim 1 or 2, comprising the steps of- obtaining further signals for heeling of a ship, engine load and possibly other signals, sending such further signals to the controller (11),- establishing data in the controller (11) for the heeling of the ship, engine load and possibly other parameters,- combining the further signals with the signal for the rotation of the at least one piston ring (216) to obtain combined data in the controller (11),- applying the combined data to determine a cleanliness of the piston rings (216) and thus also to determine a need for cleaning by activating the cleaning sequence to find the optimal result with minimal oil consumption.

4. The method of lubricating a large combustion engine according to any one of the preceding claims, comprising the steps of- using machine learning for determining when the piston ring pack needs cleaning and / or the parameters for the "cleaning sequence".

5. A large combustion engine, for example a large slow-running two-stroke engine, comprising a cylinder (1) with a liner (2) and a reciprocal piston (215) having piston rings (216) establishing contact with the liner (2) inside the cylinder (1) and with a system comprising- a lubricant supply (25),- a plurality of lubricant injectors (4) distributed along a perimeter of the cylinder (1) for injection of lubricant into the cylinder (1) at various positions on the perimeter during injection phases,- a lubricant supply conduit (12) connecting the lubricant supply (25) with the lubricant injectors (4),- a controller (11) for controlling the amount and timing of the lubricant injection by at least one of the lubricant injectors (4),- a computer (11’) to which the controller (11) is connected, wherein each injector (4) comprises- an inlet port (112) flow-connected to the lubricant supply conduit (12) for receiving lubricant from it,- a nozzle (5) with a nozzle aperture (5’) extending into the cylinder configured for injecting lubricant from the inlet port (112) into the cylinder (1) in the injection phase when using the engine in cyclic operation, wherein the engine in the injection phase provides pressure-liquid to the lubricant supply conduit (12), wherein the engine is characterised in that the engine further comprises- detectors (220) for measuring the rotation of at least one of the piston rings,- a number of desired values for lubricant amount to be injected, typically specified as a feed rate, for specific operation mode, which desired values are stored in a databasein the controller (11), and that the controller (11) is arranged for comparing the calculated actual amount to the desired value and to control the injectors (4) and adjust the setting thereof in order to obtain the desired values for lubricant amount to be injected for a specific operation mode,- transmission lines (221) for sending a signal for the rotation to the controller (11), which transmission lines (221) are electronically or wirelessly transmission lines, wherein the engine, during use in cyclic operation is arranged for- establishing data in the controller (11) for the rotation of the at least one piston ring (216), wherein the established data comprises data for the rotational speed of the at least one piston ring (226),- applying the data for the rotation to determine a cleanliness of the piston rings (216) and thus also to determine a need for cleaning and wherein the engine further comprises- a device for activating a cleaning sequence, which cleaning sequence comprises more parameters including timing, duration and distribution of the lubricant injection, wherein the device for activating the cleaning sequence either comprises a monitoring facility which makes it possible for the user to initiate the cleaning sequence and which monitoring facility is arranged for receiving the signal that the piston ring pack needs cleaning or comprises the controller (11); the controller being arranged for registering the signal that “the piston ring pack needs cleaning” in the controller and the controller is arranged for and to initiate an automatic cleaning sequence based on the registered signal that “the piston ring pack needs cleaning”.

6. The large combustion engine according to claim 5, wherein the engine further comprises- in the at least one piston ring (216) one or more radiotracers (228) or magnetic pattern producing devices,- at least one detector mounted on the engine and arranged to detect the signals from the radiotracers (228) or the magnetic pattern producing devices.

7. The large combustion engine according to claim 5 or 6, wherein the engine further comprises- a computer (11’) to which the controller (11) is connected, or alternatively- a mobile phone arranged to communicate with the controller.

8. The large combustion engine according to any one of claims 5 - 7, wherein the engine comprises a hydraulically driven inlet-valve system (113) or an electrically driven inletvalve system (113).

9. The large combustion engine according to any one of claims 5 - 8, wherein the controller (11) is arranged for calibration of the injectors (4) by measuring the lubricant amount injected at different injection-phases and mapping the results and using the results for determining the injection-phases for the injector (4) in order to obtain the de- sired lubricant amount at an injection.

Images