EP3464867B1 - Method for reducing hydrocarbon emissions and piston engine - Google Patents
Method for reducing hydrocarbon emissions and piston engine Download PDFInfo
- Publication number
- EP3464867B1 EP3464867B1 EP16736511.3A EP16736511A EP3464867B1 EP 3464867 B1 EP3464867 B1 EP 3464867B1 EP 16736511 A EP16736511 A EP 16736511A EP 3464867 B1 EP3464867 B1 EP 3464867B1
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- Prior art keywords
- engine
- fuel
- cylinder
- walls
- combustion chambers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M27/00—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like
- F02M27/04—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like by electric means, ionisation, polarisation or magnetism
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
- F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
- F02M21/0203—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels characterised by the type of gaseous fuel
- F02M21/0215—Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
Definitions
- the present invention relates to a method for reducing emissions of unburned and partially burned hydrocarbons in a piston engine in accordance with the preamble of claim 1.
- the invention also concerns a piston engine as defined in the preamble of the other independent claim.
- THC total hydrocarbon
- NMHC non-methane hydrocarbons
- An object of the present invention is to provide a method for reducing emissions of unburned and partially burned hydrocarbons in a piston engine that is operated using gaseous fuel as a main fuel.
- the characterizing features of the method according to the invention are given in the characterizing part of claim 1.
- Another object of the invention is to provide an improved piston engine that comprises means for introducing gaseous fuel into an intake duct.
- the characterizing features of the engine are given in the characterizing part of the other independent claim.
- gas molecules of the fuel are electrically charged with a predetermined polarity before being introduced into combustion chambers of the engine, and electric charge with the same polarity is applied to walls of the combustion chambers.
- the engine according to the invention comprises means for electrically charging the gaseous fuel with a predetermined polarity before the fuel is introduced into combustion chambers of the engine, and means for applying electric charge with the same polarity to the wall of each combustion chamber.
- both the fuel and the walls of the combustion chambers are positively charged.
- the electric charge is applied to an anti-polishing ring of each cylinder of the engine.
- the electric charge can be applied to the cylinder liner of each cylinder of the engine. If the electric charge is applied only to the anti-polishing rings, the charged parts are easier to electrically isolate from the rest of the engine. On the other hand, by charging the whole cylinder liner, it is ensured that the concentration of fuel in the vicinity of the combustion chamber walls is kept lower during the whole combustion process.
- the walls of combustion chambers are electrically charged using a high-voltage source.
- the high-voltage source can be, for instance, a linear output transformer.
- the voltage can be, for instance, in the range of 50 to 100 kV.
- the fuel is electrically charged with an ionizer that is arranged in a fuel feed system upstream from gas admission valves of the cylinders.
- an ionizer that is arranged in a fuel feed system upstream from gas admission valves of the cylinders.
- a magnetic field, photoionization or microwaves can be used for electrically charging the fuel.
- the engine can be operated using a lean air/fuel mixture.
- the engine is provided with an own ionizer for each cylinder of the engine.
- an own ionizer for each cylinder of the engine.
- FIG 1 is shown schematically a piston engine 1.
- the engine 1 is a large internal combustion engine, such as a main or an auxiliary engine of a ship or an engine that is used at a power plant for producing electricity.
- the cylinder bore of the engine 1 is at least 150 mm.
- the rated power of the engine 1 is at least 100 kW/cylinder.
- the engine 1 comprises a plurality of cylinders 2. In figure 1 , four cylinders 2 are shown, but the engine 1 can comprise any reasonable number of cylinders 2, which can be arranged, for instance, in line or in a V-configuration.
- the engine 1 is a gas engine or a dual-fuel or multi-fuel engine that can be operated using two or more alternative fuels.
- the engine 1 is a dual-fuel or multi-fuel engine, it can be operated in at least one gas mode, in which a gaseous fuel is used as a main fuel.
- main fuel refers to a fuel that is responsible for the major part of heat release in the cylinders 2 of the engine 1.
- the gaseous fuel can be, for instance, natural gas, biogas or associated gas from an oil drilling site.
- the engine 1 can also have a liquid fuel mode, in which a liquid fuel is used as a main fuel.
- the liquid fuel can be, for instance, light fuel oil or heavy fuel oil.
- the engine 1 In a gas mode, the engine 1 is operated according to the Otto-cycle. In a liquid fuel mode, the engine 1 can be operated according to the Diesel-cycle.
- the gaseous main fuel can be ignited either by spark plugs or with the aid of pilot fuel injection.
- the engine 1 is provided with a pilot fuel injection system.
- the engine 1 also comprises a gas feed system for introducing gaseous fuel into the cylinders 2 of the engine 1.
- the engine 1 could also comprise a further fuel injection system for introducing liquid main fuel into the cylinders 2 of the engine 1.
- the gas feed system comprises a gas admission valve 9 for each cylinder 2 of the engine 1.
- the gas admission valves 9 are used for controlling the supply of the gaseous fuel into the cylinders 2.
- the gas admission valves 9 are connected to a control unit 6, which controls opening and closing of the gas admission valves 9.
- the gaseous fuel is not introduced directly into the cylinders 2, but each gas admission valve 9 is configured to introduce the gaseous fuel into an intake duct of the engine 1 close to the intake valves of the cylinder 2.
- the gaseous fuel is thus introduced into the cylinders 2 of the engine 1 during the intake stroke.
- the gaseous fuel is mixed with the intake air to form a homogenous mixture.
- the mixture is preferably a lean mixture containing more air than is needed for complete combustion of the fuel that is introduced into the cylinders 2.
- Part of the gaseous fuel can be introduced into a prechamber for forming a richer mixture, which facilitates ignition of the fuel/air mixture.
- Each cylinder 2 can be provided with a prechamber valve for controlling the supply of the gaseous fuel into the prechamber.
- Otto combustion process is utilized.
- liquid pilot fuel is used for igniting the gaseous fuel.
- the mixture of air and the gaseous fuel could be ignited by means of spark plugs.
- the gaseous fuel is supplied to the cylinders 2 of the engine 1 from a gas tank 10 via a gas supply pipe 11.
- the gas source could also be, for instance, a pipe line or an industrial process producing combustible gas.
- the gas feed system is provided with a main gas valve 12 for controlling the pressure of the gas that is supplied to the gas admission valves 9 of the cylinders 2.
- the pilot fuel injection system shown in figure 1 is a common-rail system.
- the pilot fuel injection system comprises a pilot fuel injector 3 for each cylinder 2 of the engine 1.
- Each pilot fuel injector 3 can be individually controlled.
- the pilot fuel injectors 3 are connected to a control unit 6 for controlling the timing and duration of pilot fuel injection.
- the pilot fuel injection system comprises a low-pressure pump 4 and a high-pressure pump 5.
- the low-pressure pump 4 supplies fuel from a fuel tank 7 to the high-pressure pump 5.
- the high-pressure pump 5 supplies the fuel into a fuel rail 8 at a pressure that is suitable for direct fuel injection into the cylinders 2 of the engine 1.
- the pressure in the fuel rail 8 can be, for instance, in the range of 800 to 3000 bar.
- Each fuel injector 3 is connected to the same fuel rail 8.
- the pilot fuel injection system could also comprise more than one low-pressure and/or high-pressure pumps 4, 5. Instead of or in addition to a fuel rail that is common to all pilot fuel injectors 3, each pilot fuel injector 3 could be provided with an own fuel accumulator.
- the pilot fuel injection system could also comprise several fuel rails 8.
- the pilot fuel injection system or parts of the pilot fuel injection system could also be used for introducing liquid main fuel into the cylinders 2 of the engine 1.
- Figure 2 shows schematically one cylinder 2 of the piston engine 1 of figure 1 .
- the cylinder 2 is formed by a cylinder liner 20, which is inserted into an engine block.
- a piston 14 moves in a reciprocating manner in the cylinder 2 between bottom dead center and top dead center.
- a cylinder head 16 closes the top dead center end, i.e. the upper end of the cylinder 2.
- the piston 14 delimits together with the cylinder head 16 and the walls of the cylinder liner 20 a combustion chamber 15, in which the combustion of the fuel takes place.
- Intake air, and in the gas mode also the gaseous main fuel is introduced into the cylinder 2 via an intake duct 13.
- the gas admission valve 9 is arranged to introduce the gaseous main fuel into the intake duct 13.
- An intake valve 17 is arranged to open and close fluid communication between the combustion chamber 15 and the intake duct 13. Exhaust gas is discharged from the cylinder 2 via an exhaust duct 18. Fluid communication between the combustion chamber 15 and the exhaust duct 18 can be opened and closed by an exhaust valve 19.
- Figure 2 also shows the pilot fuel injector 3, which can be used for injecting liquid pilot fuel directly into the combustion chamber 15.
- THC total unburned or partially burned hydrocarbon
- the walls of the combustion chambers 15 are charged with a high-voltage source 24 which creates a DC voltage.
- the voltage applied to the walls of the combustion chambers can be, for instance, in the range of 50 to 100 kV.
- each cylinder liner 20 is connected to the positive terminal of the DC voltage source 24.
- Each cylinder liner 20 is thus positively charged.
- the combustion chamber walls could also be negatively charged if the fuel is negatively charged.
- the cylinder liners 20 are electrically isolated from the engine block and the cylinder heads 16 with insulation material 26.
- each cylinder 2 of the engine 1 is provided with an own ionizer 25.
- an ionizer 25 that is common to a group of cylinders 2 or all the cylinders 2 of the engine 1 could be used.
- ionization energy The energy needed for removing the most loosely bound electron from each gas molecule is called ionization energy.
- the energy can be brought into the process in many different ways, and the operation of the ionizers 25 can thus be based on many different principles. At least magnetic fields, microwaves or photoionization can be utilized. For example, in photoionization the electron is removed from a molecule when a photon collides with the molecules.
- the different operating principles can be implemented in many different ways. For instance a non-thermal plasma technology can be utilized in the ionization process.
- methane cations CH 4 +
- the concentration of the fuel is thus lower in the vicinity of the walls of the combustion chambers 15.
- Figure 3 shows an embodiment of the invention.
- the cylinder liner 20 of figure 3 differs from the cylinder liner 20 of figure 2 in that it is provided with a recess 21 for receiving an anti-polishing ring 22.
- the recess 21 is located at the upper end of the cylinder liner 20.
- the anti-polishing ring 22 is a sleeve-like element, which is used for removing carbon deposits from the piston 14.
- the inner diameter of the anti-polishing ring 22 is smaller than the inner diameter of the cylinder liner 20, but larger than the outer diameter of the piston 14 in the area above piston rings 23.
- the lower end of the anti-polishing ring 22 is at such a height that when the piston 14 is at top dead center, the lower end of the anti-polishing ring 22 is above all the piston rings 23 of the piston 14, but the upper end of the piston 14 is above the lower end of the anti-polishing ring 22.
- the anti-polishing ring 22 can thus scrape carbon deposits from a piston crown above the piston rings 23.
- the whole cylinder liner 20 is not electrically charged. Instead, the DC voltage source 24 is connected to the anti-polishing ring 22. An electrical insulation 26 is arranged between the anti-polishing ring 22 and the cylinder liner 20. Only the anti-polishing ring 22 is thus electrically charged.
- An advantage of this embodiment is that the whole cylinder liner 20 does not need to be electrically isolated from the engine block. Because most of the combustion takes place close to top dead center, a sufficient reduction of THC emissions can be achieved even with the embodiment of figure 3 .
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Description
- The present invention relates to a method for reducing emissions of unburned and partially burned hydrocarbons in a piston engine in accordance with the preamble of claim 1. The invention also concerns a piston engine as defined in the preamble of the other independent claim.
- Control of hydrocarbon emissions of internal combustion engines is important, since hydrocarbon emissions have adverse health and environmental effects. As an example of a harmful effect, methane is a strong greenhouse gas. Emission regulations often refer to total hydrocarbon (THC) emissions or to non-methane hydrocarbons (NMHC). Reduction of hydrocarbon emissions of internal combustion engines is a challenging task, since many potential measures have an adverse effect especially on NOx emissions. In gas engines, lean burn technology provides a solution for reducing NOx emissions, but THC emissions are a remaining challenge. There are different mechanisms that contribute to THC emissions. One such mechanism relates to a thermal boundary layer in the combustion chamber. In the vicinity of the walls of the combustion chamber, rapid heat exchange towards the walls of the combustion chamber has a negative effect on the combustion. As a result, fuel oxidation is ineffective causing THC emissions. Examples of methods for reducing emissions in IC engines are found in
US2766582A andJPS59108858A - An IC engine disclosing an anti-polishing ring is shown in
US5553 585A . - An object of the present invention is to provide a method for reducing emissions of unburned and partially burned hydrocarbons in a piston engine that is operated using gaseous fuel as a main fuel. The characterizing features of the method according to the invention are given in the characterizing part of claim 1. Another object of the invention is to provide an improved piston engine that comprises means for introducing gaseous fuel into an intake duct. The characterizing features of the engine are given in the characterizing part of the other independent claim.
- In the method according to the invention, gas molecules of the fuel are electrically charged with a predetermined polarity before being introduced into combustion chambers of the engine, and electric charge with the same polarity is applied to walls of the combustion chambers.
- The engine according to the invention comprises means for electrically charging the gaseous fuel with a predetermined polarity before the fuel is introduced into combustion chambers of the engine, and means for applying electric charge with the same polarity to the wall of each combustion chamber.
- Because of the electrical charging of the fuel and the combustion chamber walls, the combustion chamber walls repel the gas molecules of the fuel. Fuel concentration near the combustion chamber walls, where the combustion is not as effective as in the other parts of the combustion chambers, is thus lowered. THC emissions caused by a thermal boundary layer are thus reduced. According to an embodiment of the invention, both the fuel and the walls of the combustion chambers are positively charged.
- According to the invention, the electric charge is applied to an anti-polishing ring of each cylinder of the engine. In addition, the electric charge can be applied to the cylinder liner of each cylinder of the engine. If the electric charge is applied only to the anti-polishing rings, the charged parts are easier to electrically isolate from the rest of the engine. On the other hand, by charging the whole cylinder liner, it is ensured that the concentration of fuel in the vicinity of the combustion chamber walls is kept lower during the whole combustion process.
- According to an embodiment of the invention, the walls of combustion chambers are electrically charged using a high-voltage source. The high-voltage source can be, for instance, a linear output transformer. The voltage can be, for instance, in the range of 50 to 100 kV.
- According to an embodiment of the invention, the fuel is electrically charged with an ionizer that is arranged in a fuel feed system upstream from gas admission valves of the cylinders. For example a magnetic field, photoionization or microwaves can be used for electrically charging the fuel.
- The engine can be operated using a lean air/fuel mixture.
- According to an embodiment of the invention, the engine is provided with an own ionizer for each cylinder of the engine. However, it is also possible to provide the engine with one ionizer that is common to several or all cylinders of the engine.
- Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which
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Fig. 1 shows schematically a piston engine, -
Fig. 2 shows a cylinder of a piston engine not in accordance with the invention and -
Fig. 3 shows a cylinder of the engine in accordance with another embodiment of the invention. - In
figure 1 is shown schematically a piston engine 1. The engine 1 is a large internal combustion engine, such as a main or an auxiliary engine of a ship or an engine that is used at a power plant for producing electricity. The cylinder bore of the engine 1 is at least 150 mm. The rated power of the engine 1 is at least 100 kW/cylinder. The engine 1 comprises a plurality ofcylinders 2. Infigure 1 , fourcylinders 2 are shown, but the engine 1 can comprise any reasonable number ofcylinders 2, which can be arranged, for instance, in line or in a V-configuration. The engine 1 is a gas engine or a dual-fuel or multi-fuel engine that can be operated using two or more alternative fuels. If the engine 1 is a dual-fuel or multi-fuel engine, it can be operated in at least one gas mode, in which a gaseous fuel is used as a main fuel. The expression "main fuel" refers to a fuel that is responsible for the major part of heat release in thecylinders 2 of the engine 1. Preferably, at least 90 % of the heat that is released in acylinder 2 is released by combustion of the main fuel. The gaseous fuel can be, for instance, natural gas, biogas or associated gas from an oil drilling site. The engine 1 can also have a liquid fuel mode, in which a liquid fuel is used as a main fuel. The liquid fuel can be, for instance, light fuel oil or heavy fuel oil. In a gas mode, the engine 1 is operated according to the Otto-cycle. In a liquid fuel mode, the engine 1 can be operated according to the Diesel-cycle. - In the gas mode, the gaseous main fuel can be ignited either by spark plugs or with the aid of pilot fuel injection. In the embodiment of the figures, the engine 1 is provided with a pilot fuel injection system. The engine 1 also comprises a gas feed system for introducing gaseous fuel into the
cylinders 2 of the engine 1. The engine 1 could also comprise a further fuel injection system for introducing liquid main fuel into thecylinders 2 of the engine 1. - The gas feed system comprises a
gas admission valve 9 for eachcylinder 2 of the engine 1. Thegas admission valves 9 are used for controlling the supply of the gaseous fuel into thecylinders 2. Thegas admission valves 9 are connected to acontrol unit 6, which controls opening and closing of thegas admission valves 9. The gaseous fuel is not introduced directly into thecylinders 2, but eachgas admission valve 9 is configured to introduce the gaseous fuel into an intake duct of the engine 1 close to the intake valves of thecylinder 2. The gaseous fuel is thus introduced into thecylinders 2 of the engine 1 during the intake stroke. The gaseous fuel is mixed with the intake air to form a homogenous mixture. The mixture is preferably a lean mixture containing more air than is needed for complete combustion of the fuel that is introduced into thecylinders 2. Part of the gaseous fuel can be introduced into a prechamber for forming a richer mixture, which facilitates ignition of the fuel/air mixture. Eachcylinder 2 can be provided with a prechamber valve for controlling the supply of the gaseous fuel into the prechamber. When acylinder 2 is operated using the gaseous fuel as the main fuel, Otto combustion process is utilized. In the embodiment of the figures, liquid pilot fuel is used for igniting the gaseous fuel. Alternatively, the mixture of air and the gaseous fuel could be ignited by means of spark plugs. The gaseous fuel is supplied to thecylinders 2 of the engine 1 from agas tank 10 via agas supply pipe 11. The gas source could also be, for instance, a pipe line or an industrial process producing combustible gas. The gas feed system is provided with amain gas valve 12 for controlling the pressure of the gas that is supplied to thegas admission valves 9 of thecylinders 2. - The pilot fuel injection system shown in
figure 1 is a common-rail system. The pilot fuel injection system comprises apilot fuel injector 3 for eachcylinder 2 of the engine 1. Eachpilot fuel injector 3 can be individually controlled. Thepilot fuel injectors 3 are connected to acontrol unit 6 for controlling the timing and duration of pilot fuel injection. The pilot fuel injection system comprises a low-pressure pump 4 and a high-pressure pump 5. The low-pressure pump 4 supplies fuel from afuel tank 7 to the high-pressure pump 5. The high-pressure pump 5 supplies the fuel into afuel rail 8 at a pressure that is suitable for direct fuel injection into thecylinders 2 of the engine 1. The pressure in thefuel rail 8 can be, for instance, in the range of 800 to 3000 bar. Eachfuel injector 3 is connected to thesame fuel rail 8. The pilot fuel injection system could also comprise more than one low-pressure and/or high-pressure pumps 4, 5. Instead of or in addition to a fuel rail that is common to allpilot fuel injectors 3, eachpilot fuel injector 3 could be provided with an own fuel accumulator. The pilot fuel injection system could also comprise several fuel rails 8. The pilot fuel injection system or parts of the pilot fuel injection system could also be used for introducing liquid main fuel into thecylinders 2 of the engine 1. -
Figure 2 shows schematically onecylinder 2 of the piston engine 1 offigure 1 . Thecylinder 2 is formed by acylinder liner 20, which is inserted into an engine block. Apiston 14 moves in a reciprocating manner in thecylinder 2 between bottom dead center and top dead center. Acylinder head 16 closes the top dead center end, i.e. the upper end of thecylinder 2. Thepiston 14 delimits together with thecylinder head 16 and the walls of the cylinder liner 20 acombustion chamber 15, in which the combustion of the fuel takes place. Intake air, and in the gas mode also the gaseous main fuel, is introduced into thecylinder 2 via anintake duct 13. Thegas admission valve 9 is arranged to introduce the gaseous main fuel into theintake duct 13. Anintake valve 17 is arranged to open and close fluid communication between thecombustion chamber 15 and theintake duct 13. Exhaust gas is discharged from thecylinder 2 via anexhaust duct 18. Fluid communication between thecombustion chamber 15 and theexhaust duct 18 can be opened and closed by anexhaust valve 19.Figure 2 also shows thepilot fuel injector 3, which can be used for injecting liquid pilot fuel directly into thecombustion chamber 15. - In a gas engine, a significant part of the total unburned or partially burned hydrocarbon (THC) emissions is created close to the walls of the
combustion chambers 15. In a thermal boundary layer that is located adjacent to the walls of thecombustion chamber 15, the rapid heat exchange rate towards the combustion chamber walls disturbs combustion, and as a result THC emissions are formed. In accordance with the invention, this phenomenon is decreased by applying an electric charge with the same polarity to the gas molecules of the fuel and the walls of thecombustion chambers 15. The combustion chamber walls and the fuel thus repel each other, which lowers the fuel concentration in the thermal boundary layer. As a result, the fuel is more effectively combusted and less THC emissions are formed. - The walls of the
combustion chambers 15 are charged with a high-voltage source 24 which creates a DC voltage. The voltage applied to the walls of the combustion chambers can be, for instance, in the range of 50 to 100 kV. In the embodiment offigure 2 , eachcylinder liner 20 is connected to the positive terminal of theDC voltage source 24. Eachcylinder liner 20 is thus positively charged. However, the combustion chamber walls could also be negatively charged if the fuel is negatively charged. Thecylinder liners 20 are electrically isolated from the engine block and the cylinder heads 16 withinsulation material 26. - Before the gaseous fuel is introduced via the
gas admission valves 9 into theintake duct 13 and further into thecombustion chambers 15, the gas molecules of the fuel are electrically charged, i.e. ionized. For charging the fuel, anionizer 25 is arranged upstream from thegas admission valves 9. In the embodiment of the figures, eachcylinder 2 of the engine 1 is provided with anown ionizer 25. However, also anionizer 25 that is common to a group ofcylinders 2 or all thecylinders 2 of the engine 1 could be used. - In case the fuel is positively charged, a free electron and a cation are created in the ionization process. The energy needed for removing the most loosely bound electron from each gas molecule is called ionization energy. The energy can be brought into the process in many different ways, and the operation of the
ionizers 25 can thus be based on many different principles. At least magnetic fields, microwaves or photoionization can be utilized. For example, in photoionization the electron is removed from a molecule when a photon collides with the molecules. The different operating principles can be implemented in many different ways. For instance a non-thermal plasma technology can be utilized in the ionization process. In case natural gas is used as the gaseous fuel, methane cations (CH4 +) are formed. As the cations enter thecombustions chambers 15, they are repelled by the positively chargedcylinder liners 20. The concentration of the fuel is thus lower in the vicinity of the walls of thecombustion chambers 15. -
Figure 3 shows an embodiment of the invention. Thecylinder liner 20 offigure 3 differs from thecylinder liner 20 offigure 2 in that it is provided with arecess 21 for receiving ananti-polishing ring 22. Therecess 21 is located at the upper end of thecylinder liner 20. Theanti-polishing ring 22 is a sleeve-like element, which is used for removing carbon deposits from thepiston 14. The inner diameter of theanti-polishing ring 22 is smaller than the inner diameter of thecylinder liner 20, but larger than the outer diameter of thepiston 14 in the area above piston rings 23. The lower end of theanti-polishing ring 22 is at such a height that when thepiston 14 is at top dead center, the lower end of theanti-polishing ring 22 is above all the piston rings 23 of thepiston 14, but the upper end of thepiston 14 is above the lower end of theanti-polishing ring 22. Theanti-polishing ring 22 can thus scrape carbon deposits from a piston crown above the piston rings 23. - In the embodiment of
figure 3 , thewhole cylinder liner 20 is not electrically charged. Instead, theDC voltage source 24 is connected to theanti-polishing ring 22. Anelectrical insulation 26 is arranged between theanti-polishing ring 22 and thecylinder liner 20. Only theanti-polishing ring 22 is thus electrically charged. An advantage of this embodiment is that thewhole cylinder liner 20 does not need to be electrically isolated from the engine block. Because most of the combustion takes place close to top dead center, a sufficient reduction of THC emissions can be achieved even with the embodiment offigure 3 . - It will be appreciated by a person skilled in the art that the invention is not limited to the embodiment described above, but may vary within the scope of the appended claims.
Claims (15)
- A method for reducing emissions of unburned and partially burned hydrocarbons in a piston engine (1) that is operated using gaseous fuel as a main fuel, wherein gas molecules of the fuel are electrically charged with a predetermined polarity before being introduced into combustion chambers (15) of the engine (1), and electric charge with the same polarity is applied to walls of the combustion chambers (15), characterized in that the electric charge is applied to an anti-polishing ring (22) of each cylinder (2) of the engine (1).
- A method according to claim 1, wherein both the fuel and the walls of the combustion chambers (15) are positively charged.
- A method according to claim 1 or 2, wherein the electric charge is applied to the cylinder liner (20) of each cylinder (2) of the engine (1).
- A method according to any of the preceding claims, wherein the walls of combustion chambers (15) are electrically charged using a high-voltage source (24).
- A method according to claim 4, wherein the high-voltage source (24) is a linear output transformer.
- A method according to any of the preceding claims, wherein the voltage applied to the walls of the combustion chambers (15) is in the range of 50 to 100 kV.
- A method according to any of the preceding claims, wherein the fuel is electrically charged with an ionizer (25) that is arranged in a fuel feed system upstream from gas admission valves (9) of the cylinders (2).
- A method according to any of the preceding claims, wherein the fuel is electrically charged using a magnetic field, photoionization or microwaves.
- A method according to any of the preceding claims, wherein the engine (1) is operated using a lean air/fuel mixture.
- A piston engine (1) comprising means (9) for introducing gaseous fuel into an intake duct (13), means (25) for electrically charging the gaseous fuel with a predetermined polarity before the fuel is introduced into combustion chambers (15) of the engine (1), and means (25) for applying electric charge with the same polarity to the wall of each combustion chamber (15), characterized in that the engine (1) comprises means for applying the electric charge to an anti-polishing ring (22) of each cylinder (2) of the engine (1).
- An engine (1) according to claim 10, wherein the means (24) for charging the combustion chamber walls is a high-voltage source.
- An engine (1) according to claim 11, wherein the high-voltage source (24) is a linear output transformer.
- An engine (1) according to any of claims 10 to 12, wherein the means (25) for charging the fuel comprises an ionizer.
- An engine (1) according to claim 13, wherein the engine (1) is provided with an own ionizer (25) for each cylinder (2) of the engine (1).
- An engine (1) according to claim 13 or 14, wherein the operation of the ionizer (25) is based on a magnetic field, photoionization or microwaves.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/FI2016/050390 WO2017207864A1 (en) | 2016-06-01 | 2016-06-01 | Method for reducing hydrocarbon emissions and piston engine |
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EP3464867A1 EP3464867A1 (en) | 2019-04-10 |
EP3464867B1 true EP3464867B1 (en) | 2020-03-25 |
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EP16736511.3A Active EP3464867B1 (en) | 2016-06-01 | 2016-06-01 | Method for reducing hydrocarbon emissions and piston engine |
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EP (1) | EP3464867B1 (en) |
KR (1) | KR101970116B1 (en) |
CN (1) | CN109312695B (en) |
WO (1) | WO2017207864A1 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US5553585A (en) * | 1994-05-27 | 1996-09-10 | Wartsila Diesel International Ltd Oy | Anti-polishing ring |
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---|---|---|---|---|
BE482563A (en) * | ||||
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2016
- 2016-06-01 EP EP16736511.3A patent/EP3464867B1/en active Active
- 2016-06-01 KR KR1020187034727A patent/KR101970116B1/en active IP Right Grant
- 2016-06-01 WO PCT/FI2016/050390 patent/WO2017207864A1/en unknown
- 2016-06-01 CN CN201680086228.4A patent/CN109312695B/en active Active
Patent Citations (1)
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US5553585A (en) * | 1994-05-27 | 1996-09-10 | Wartsila Diesel International Ltd Oy | Anti-polishing ring |
Also Published As
Publication number | Publication date |
---|---|
CN109312695B (en) | 2020-09-08 |
EP3464867A1 (en) | 2019-04-10 |
CN109312695A (en) | 2019-02-05 |
WO2017207864A1 (en) | 2017-12-07 |
KR101970116B1 (en) | 2019-08-13 |
KR20180136554A (en) | 2018-12-24 |
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