US20220120209A1 - Combustion pre-chamber for an internal combustion engine - Google Patents
Combustion pre-chamber for an internal combustion engine Download PDFInfo
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- US20220120209A1 US20220120209A1 US17/073,822 US202017073822A US2022120209A1 US 20220120209 A1 US20220120209 A1 US 20220120209A1 US 202017073822 A US202017073822 A US 202017073822A US 2022120209 A1 US2022120209 A1 US 2022120209A1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B19/00—Engines characterised by precombustion chambers
- F02B19/12—Engines characterised by precombustion chambers with positive ignition
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B19/00—Engines characterised by precombustion chambers
- F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B19/00—Engines characterised by precombustion chambers
- F02B19/16—Chamber shapes or constructions not specific to sub-groups F02B19/02 - F02B19/10
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B19/00—Engines characterised by precombustion chambers
- F02B19/16—Chamber shapes or constructions not specific to sub-groups F02B19/02 - F02B19/10
- F02B19/18—Transfer passages between chamber and cylinder
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
- F02B23/10—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder
- F02B23/104—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder the injector being placed on a side position of the cylinder
- F02B23/105—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder the injector being placed on a side position of the cylinder the fuel is sprayed directly onto or close to the spark plug
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F1/242—Arrangement of spark plugs or injectors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
- F02F1/4235—Shape or arrangement of intake or exhaust channels in cylinder heads of intake channels
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
- F02F1/4264—Shape or arrangement of intake or exhaust channels in cylinder heads of exhaust channels
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
- F02F1/4285—Shape or arrangement of intake or exhaust channels in cylinder heads of both intake and exhaust channel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F7/00—Casings, e.g. crankcases or frames
- F02F7/0021—Construction
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
- F02B23/10—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder
- F02B2023/102—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder the spark plug being placed offset the cylinder centre axis
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F2200/00—Manufacturing
- F02F2200/06—Casting
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- Various embodiments relate to an internal combustion engine with a combustion pre-chamber.
- Internal combustion engines may be provided with a combustion pre-chamber positioned within the cylinder, with a two-stage combustion process from the pre-chamber and into the main combustion chamber of the cylinder.
- an internal combustion engine is provided with a cylinder head having a cylinder roof defining first and second intake ports.
- the cylinder head supports a spark plug positioned between a central axis of the cylinder roof and a fuel injector.
- the cylinder head has a combustion pre-chamber connected to and extends outwardly from the roof of the cylinder.
- the pre-chamber encapsulates the spark plug, and is offset from the central axis and positioned between the central axis and the first and second intake ports.
- the pre-chamber defines an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defines first and second side apertures. Each side aperture is positioned adjacent to a respective one of the first and second intake ports.
- a method for operating an engine is provided.
- a fuel-air mixture is ignited within a combustion pre-chamber via a spark plug positioned inside a cavity defined by the combustion pre-chamber.
- the combustion pre-chamber is supported by and extends outwardly from a cylinder head of the engine and into a main combustion chamber of a cylinder.
- the combustion pre-chamber and spark plug are offset from a central axis of the cylinder.
- Exhaust gases are vented from within the combustion pre-chamber to the main combustion chamber via an inlet aperture, an outlet aperture, a first side aperture, and a second side aperture defined by the pre-chamber thereby igniting another fuel-air mixture within the main combustion chamber.
- Exhaust gases are purged from within the combustion pre-chamber via the outlet aperture into the main combustion chamber during an intake stroke by flowing intake air flow from first and second intake valves into the pre-chamber via the first and second side apertures.
- FIG. 1 illustrates a schematic of an internal combustion engine capable of implementing the disclosed embodiments
- FIG. 2 illustrates a schematic view of a combustion pre-chamber and a roof of a cylinder head according to an embodiment
- FIG. 3 illustrates a side schematic view of the combustion pre-chamber of FIG. 2 ;
- FIG. 4 illustrates a schematic view of the combustion pre-chamber and roof of FIG. 2 taken along the A-A section line during an injection process
- FIG. 5 illustrates a schematic view of the combustion pre-chamber and roof of FIG. 2 taken along the B-B section line during the injection process of FIG. 4 ;
- FIG. 6 illustrates a schematic view of the combustion pre-chamber and roof of FIG. 2 taken along the B-B section line during an intake stroke and with the intake valves opened.
- FIG. 1 illustrates a schematic of an internal combustion engine 20 .
- the engine 20 has a plurality of cylinders 22 , and one cylinder is illustrated.
- the cylinder 22 is formed by cylinder walls 32 and piston 34 .
- the piston 34 is connected to a crankshaft 36 .
- the cylinder 22 is in fluid communication with the intake manifold 38 and the exhaust manifold 40 .
- One or more intake valves 42 controls flow from the intake manifold 38 into the combustion chamber.
- One or more exhaust valves 44 controls flow from the combustion chamber to the exhaust manifold 40 .
- the intake and exhaust valves 42 , 44 may be operated in various ways as is known in the art to control the engine operation. The operation of the intake valve 42 and exhaust valve 44 are described in greater detail below.
- a fuel injector 46 delivers fuel from a fuel system directly into the cylinder 22 such that the engine is a direct injection engine.
- a low pressure or high pressure fuel injection system may be used with the engine 20 .
- An ignition system includes a spark plug 48 that is controlled to provide energy in the form of a spark to ignite a fuel air mixture in the combustion chamber.
- the spark plug 48 may be located in various positions within the cylinder 22 .
- the engine 20 includes a controller and various sensors configured to provide signals to the controller for use in controlling the air and fuel delivery to the engine, the ignition timing, valve timing, the power and torque output from the engine, and the like.
- Engine sensors may include, but are not limited to, an oxygen sensor in the exhaust manifold 40 , an engine coolant temperature, an accelerator pedal position sensor, an engine manifold pressure (MAP) sensor, an engine position sensor for crankshaft position, an air mass sensor in the intake manifold 38 , a throttle position sensor, and the like.
- the engine 20 is used as the sole prime mover in a vehicle, such as a conventional vehicle, or a stop-start vehicle. In other embodiments, the engine may be used in a hybrid vehicle where an additional prime mover, such as an electric machine, is available to provide additional power to propel the vehicle.
- a vehicle such as a conventional vehicle, or a stop-start vehicle.
- the engine may be used in a hybrid vehicle where an additional prime mover, such as an electric machine, is available to provide additional power to propel the vehicle.
- Each cylinder 22 may operate under a four-stroke cycle including an intake stroke, a compression stroke, an ignition stroke, and an exhaust stroke. In other embodiments, the engine may operate with a two-stroke cycle.
- the piston 34 position at the top of the cylinder 22 is generally known as top dead center (TDC).
- the piston 34 position at the bottom of the cylinder is generally known as bottom dead center (BDC).
- the intake valve(s) 42 opens and the exhaust valve(s) 44 closes while the piston 34 moves from the top of the cylinder 22 to the bottom of the cylinder 22 to introduce intake gases, e.g. air, from the intake manifold to the combustion chamber.
- intake gases e.g. air
- Fuel may be introduced into the cylinder 22 while the piston 34 moves down during the intake stroke.
- the intake and exhaust valves 42 , 44 are closed.
- the piston 34 moves from the bottom towards the top of the cylinder 22 to compress the air/fuel mixture within the cylinder 22 .
- the compressed air/fuel mixture is then ignited within the cylinder 22 .
- the fuel is injected into the cylinder 22 and is then ignited using spark plug 48 .
- Fuel injection and ignition according to the present disclosure is described below in greater detail.
- the ignited fuel-air mixture in the cylinder 22 expands, thereby causing the piston 34 to move from the top of the cylinder 22 to the bottom of the cylinder 22 .
- the movement of the piston 34 causes a corresponding movement in crankshaft 36 and provides for a mechanical torque output from the engine 20 .
- the intake valve(s) 42 remains closed, and the exhaust valve(s) 44 opens.
- the piston 34 moves from the bottom of the cylinder to the top of the cylinder 22 to remove the exhaust gases and combustion products from the cylinder 22 by reducing the volume of the cylinder 22 .
- the exhaust gases flow from the cylinder 22 to the exhaust manifold 40 and to an aftertreatment system such as a catalytic converter.
- the intake and exhaust valves 42 , 44 positions and timing, as well as the fuel injection timing and ignition timing may be varied for the various engine strokes.
- the engine 20 has an engine cylinder block 50 and a cylinder head 52 .
- a head gasket 54 is interposed between the cylinder block 50 and the cylinder head 52 to seal the cylinders 22 .
- the cylinder head defines a roof 60 .
- the roof 60 cooperates with the block 50 to define the cylinder 22 .
- the roof 60 of the cylinder head 52 defines at least one intake air port 62 that receives an associated intake valve 42 .
- the intake air port 62 provides a passage for flow of intake air or intake gases from the intake manifold 38 to a respective cylinder 22 .
- Intake air may include outside or environmental air, may include fuel mixed therein, and may also be mixed with exhaust gases from an exhaust gas recirculation system, etc.
- the roof of the cylinder head 52 defines at least one exhaust gas port 64 that receives an associated exhaust valve 44 .
- the exhaust gas port 64 provides a passage for flow of exhaust gases from each cylinder 22 to the exhaust manifold 40 .
- the intake port(s) 62 and exhaust port(s) 64 may be offset from the central axis 66 .
- the spark plug assembly 48 may be offset from the central axis 66 , and in one example, may be adjacent to the intake port(s) 62 as further described below.
- the fuel injector 46 may likewise be offset from the central axis 66 .
- the engine 20 may be provided with a combustion pre-chamber 80 .
- the combustion pre-chamber 80 may be used to increase combustion stability in the engine 20 , for example, when used with an engine 20 having exhaust gas recirculation (EGR).
- EGR may be used to increase engine thermal efficiencies; however, EGR may reduce combustion stability in the engine 20 , as well as result in increased levels of noise, vibration, and harshness (NVH).
- a combustion pre-chamber is provided in the center of the cylinder, such that there may be challenges in purging residual gases after a combustion event within the pre-chamber, e.g. purging exhaust gases or combustion byproducts from the combustion pre-chamber.
- FIGS. 2-6 illustrate a combustion pre-chamber 80 according to the present disclosure.
- the combustion pre-chamber may be used with the engine 20 as described above.
- the combustion pre-chamber 80 provides for increased purging of the residual gases or exhaust gases within the pre-chamber.
- elements that are the same as or similar to those described above with respect to FIG. 1 are given the same reference number.
- the pre-chamber 80 may be formed as a hollow body defining a cavity.
- the pre-chamber 80 is formed with a continuous side wall that extends outwardly from the roof 60 of the cylinder head, and a lower wall that is spaced apart from the roof.
- the pre-chamber 80 may be formed with the side wall and lower wall blended together in a continuous curve.
- the pre-chamber 80 may be formed with a continuous curved wall.
- the continuous curved wall may have a constant radius of curvature such that the pre-chamber 80 is formed as a section or portion of a sphere.
- the pre-chamber 80 may be formed as a spherical dome from a majority section of a sphere as shown schematically in FIG. 3 .
- the pre-chamber 80 is formed as a spherical dome from between 60-85% of a sphere, or between 60-75% of a sphere.
- the continuous curved wall has a varying radius of curvature.
- the pre-chamber 80 defines a cavity 82 therein, such that the volume of the cylinder 22 is divided into the pre-chamber 80 and a main combustion chamber 84 .
- the main combustion chamber is the region of the cylinder 22 that is outside the pre-chamber 80 .
- the spark plug assembly 48 is offset from the central axis 66 of the cylinder, and is positioned in a region of the cylinder roof 60 that is between the central axis 66 and the first and second intake ports 62 .
- the spark plug assembly 48 is positioned between the fuel injector 46 and the central axis 66 .
- the fuel injector 46 is therefore also offset from the central axis 66 , and may be positioned within the cylinder 22 such that it is adjacent to the intake ports 62 , and spaced apart from the exhaust ports 64 .
- the pre-chamber 80 is connected to the roof 60 of the cylinder head such that the spark plug assembly 48 is received within the cavity 82 defined by the pre-chamber 80 .
- the pre-chamber 80 may encapsulate the spark plug assembly 48 .
- the pre-chamber 80 is therefore offset from the central axis 66 , and is positioned between the first and second intake ports 62 , and is positioned between the central axis 66 and the first and second intake ports 62 as shown in FIG. 2 .
- the combustion pre-chamber 80 is positioned between the central axis 66 of the cylinder and a first line 90 extending through the center axes of both intake valves 42 or centers of the intake ports 60 .
- the combustion pre-chamber 80 is positioned such that an acute angle ⁇ is formed between the first line 90 and a second line 92 extending through the center axis of the first intake valve 42 or intake port 60 and the central axis 66 of the combustion pre-chamber.
- the combustion pre-chamber 80 is also positioned such that an acute angle ⁇ is formed between the first line 90 and a third line 94 extending through the center axis of the second intake valve 42 or intake port 62 and the central axis 66 of the combustion pre-chamber.
- Each of the acute angles ⁇ , ⁇ may be in the range of 15-20 degrees, although other acute angle ranges are also contemplated.
- the two acute angles ⁇ , ⁇ may be the same as one another.
- the pre-chamber 80 defines an inlet aperture 100 and an outlet aperture 102 .
- the inlet aperture 100 and the outlet aperture 102 may be opposite to one another on the pre-chamber 80 .
- the inlet aperture 100 and outlet aperture 102 may be positioned along a spray streamline 104 of the fuel injector 46 , with the inlet aperture 100 positioned between the fuel injector 46 and the outlet aperture 102 .
- the outlet aperture 102 may be positioned to face the central axis 66 , or may be positioned to face generally towards the first and second exhaust ports 64 , or the region of the roof defining the first and second exhaust ports 64 .
- the fuel injector 46 may have multiple spray streamlines, with only the spray streamline 104 directed to the pre-chamber 80 being shown. The remaining spray streamlines may direct fuel into the main combustion chamber 84 during an injection event.
- the pre-chamber 80 also defines a first side aperture 106 and a second side aperture 108 .
- the pre-chamber 80 has only one first side aperture 106 and only one second side aperture 108 , such that the pre-chamber 80 has only four apertures 100 , 102 , 106 , 108 in total when it is assembled to the engine 20 .
- the pre-chamber 80 may have two or more first side apertures 106 and two or more second side apertures 108 .
- the first side aperture 106 is positioned adjacent to the first intake port 62
- the second side aperture 108 is positioned adjacent to the second intake port 62 .
- the spray streamline 104 from the fuel injector therefore extends through the pre-chamber 80 and between the first and second side apertures 106 , 108 .
- the cross-sectional area of the outlet aperture 102 may be greater than a cross-sectional area of the inlet aperture 100 . Furthermore, the cross-sectional area of the outlet aperture 102 may be greater than a cross-sectional area of the first side aperture 106 and greater than a cross-sectional area of the second side aperture 108 . The cross-sectional area of the inlet aperture 100 may be less than a cross-sectional area of the first side aperture 106 and also less than a cross-sectional area of the second side aperture 108 . The first and second side apertures 106 , 108 may each have the same cross-sectional area as one another.
- the inlet aperture 100 has a cross-sectional area of 1.2 mm 2
- the first and second side apertures 106 , 108 each have a cross-sectional area of 1.8 mm 2
- the outlet aperture 102 has a cross-sectional area of 3 mm 2 .
- a centerline of the fuel injector 46 may be oriented at an acute angle relative to the central axis 66 of the cylinder, as shown in FIGS. 3 and 4 .
- a spray 104 of fuel from the fuel injector 46 is directed towards the pre-chamber 80 , and this spray 104 of fuel enters the pre-chamber via the inlet aperture 100 .
- the remainder of fuel injected by the fuel injector 46 is directed into the main combustion chamber 84 .
- the inlet aperture 100 is therefore aligned or generally aligned with the spray 104 streamline from the fuel injector.
- the inlet aperture 100 therefore receives a spray 104 of fuel with a first portion of fuel from the fuel injector 46 during a fuel injection process.
- a second portion of fuel from the spray 104 of fuel exits the pre-chamber 80 via the outlet aperture 102 during the fuel injection process, with the second portion being less than the first portion.
- the spray 104 of fuel therefore has some fuel that passes through the pre-chamber 80 and back into the main chamber 84 .
- a remainder of the fuel remains in the cavity 82 of the pre-chamber 80 , and this amount may be equivalent to the first portion of fuel minus the second portion of fuel in the spray 104 .
- only 3-5% by volume of the total fuel injected into the pre-chamber 80 remains in the pre-chamber 80 after the injection process and prior to an ignition event.
- the high velocity of the spray 104 across the pre-chamber 80 creates a vacuum of low pressure region within the pre-chamber 80 compared to the main chamber 84 .
- the local pressure within the pre-chamber 80 is therefore less than the local pressure in the main combustion chamber 84 .
- the spray 104 of fuel may push residual gases out of the pre-chamber 80 via the outlet aperture 102 .
- the low pressure created in the pre-chamber 80 by the spray 104 of fuel therethrough causes intake air or gases within the main combustion chamber 84 to flow into the pre-chamber 80 via the first and second side apertures 106 , 108 .
- FIG. 4 illustrates the injection process with a spray 104 of fuel through the pre-chamber 80
- FIG. 5 illustrates intake air or gas in the main chamber 84 being drawn into the pre-chamber 80 via the side apertures 106 , 108 .
- the spark plug assembly 48 may then be activated or sparked to ignite the fuel-air mixture within the pre-chamber 80 . As the end of the spark plug assembly 48 is located within the pre-chamber 80 , the fuel-air mixture within the pre-chamber 80 ignites prior to any combustion event in the main combustion chamber 84 .
- the fuel-air charge in the pre-chamber 80 is ignited by the spark plug assembly 48 and the flame propagates across and within the cavity 82 of the pre-chamber 80 .
- hot exhaust gases or combustion byproduct gases in the pre-chamber 80 vent or exit out of the pre-chamber 80 and into the main combustion chamber 84 via the inlet aperture 100 , outlet aperture 102 , and side apertures 106 , 108 to ignite the fuel-air charge in the main combustion chamber 84 .
- the positioning of the apertures 100 , 102 , 106 , 108 directs the hot exhaust gases into different regions of the main combustion chamber 84 in the cylinder to provide multiple ignition points of the fuel-air charge in the main combustion chamber 84 .
- the pre-chamber 80 therefore provides for a two-stage combustion process within the cylinder 22 .
- the first stage is provided by the spark plug 48 ignition and a combustion event in the pre-chamber 80 .
- the second stage is provided by ignition in the main chamber 84 caused by the exhaust gases from the pre-chamber 80 flowing into and igniting the fuel-air mixture in the main chamber 84 .
- the outlet aperture 102 may have a larger cross-sectional area than the inlet aperture 100 both to allow for and control the exit of a portion of the fuel spray 104 from the pre-chamber, as well as to direct a larger proportion of hot exhaust gases from the pre-chamber 80 , towards the exhaust port 64 side of the cylinder 22 based on the offset location of the pre-chamber 80 in the cylinder.
- the larger outlet aperture 102 cross-sectional area therefore provides for a control over the flow of hot exhaust gases from the pre-chamber 80 into the main combustion chamber 84 , and improved ignition of the fuel-air charge in the main combustion chamber 84 in the exhaust port 64 region of the main combustion chamber 84 and cylinder.
- the cross-sectional areas of the inlet aperture 100 , outlet aperture 102 , and side apertures 106 , 108 may be therefore sized to control the flow of hot exhaust gases from the pre-chamber 80 into the main combustion chamber 84 .
- the cross-section areas of the pre-chamber apertures 100 , 102 , 106 , 108 may therefore be a function of the distance to the cylinder 22 wall that the respective aperture faces, with the cross-sectional area increasing in size with increased distance to the cylinder 22 side wall.
- the pre-chamber 80 is further purged during the intake stroke and with the intake valves 42 opened, as shown in FIG. 6 .
- intake stroke the piston moves down and away from the cylinder head, which creates a vacuum or low pressure within the cylinder 22 and draws intake air into the cylinder via the intake ports 62 and opened intake valves 42 .
- intake air may include exhaust gases recirculated from the engine exhaust (EGR) as well as outside air.
- EGR engine exhaust
- the first and second side apertures 106 , 108 are positioned adjacent to the first and second intake ports 62 to aid in the flow of intake air into the pre-chamber 80 .
- the first and second side apertures 106 , 108 may be positioned between the roof 60 of the cylinder and the bottom or face of the associated intake valve 42 with the intake valve 42 in a fully open position, as shown in FIG. 6 . This intermediate position for the side apertures 106 , 108 may aid the flow of intake air from the intake ports 62 into the pre-chamber 80 as well as purge combustion byproducts from the prior combustion cycle from the pre-chamber 80 during the intake stroke.
- the pre-chamber 80 therefore provides for control over an amount of fuel within the pre-chamber 80 at an ignition event, and also allows for a multi-stage purge process of the pre-chamber 80 to remove combusted residual gases from the pre-chamber 80 and provide a charge of intake air into the pre-chamber 80 prior to a subsequent ignition event. This may result in a more robust and stable combustion event for the engine 20 , and may be used with engines that are being operated at a high dilution or fuel lean condition, or with EGR.
- the engine may be the engine 20 as described above. Elements that are the same as or similar to those described above are given the same reference number for simplicity.
- An engine 20 has a cylinder head 52 with a pre-chamber 80 .
- the cylinder head 52 and pre-chamber 80 are formed together as an integral component during a casting process.
- the cylinder head 52 and pre-chamber 80 may be formed as separate components, with the pre-chamber machined to the desired size and shape and then attached to the roof 60 of the cylinder via a welding process, via fasteners, or the like.
- the pre-chamber 80 may be formed with or may have apertures 100 , 102 , 106 , 108 machined through it.
- the pre-chamber 80 may be formed with an inlet aperture 100 , an outlet aperture 102 , and first and second side apertures 106 , 108 .
- the first and second side apertures 106 , 108 may be positioned between a roof 60 of the cylinder and a face of the first intake valve 42 when the first intake valve is in a fully open position.
- Fuel is injected into the cylinder 22 using a fuel injector 46 .
- a spray 104 of fuel from the fuel injector is received by the pre-chamber 80 via the inlet aperture 100 .
- Exhaust gases or residual gases are purged in a first purging stage from the pre-chamber 80 while injecting fuel into the cylinder 22 .
- a portion of the spray 104 of fuel flows out of the pre-chamber 80 via the outlet aperture 102 and thereby pushes residual gases out of the pre-chamber 80 via the outlet aperture 102 while drawing air from the main combustion chamber 84 into the pre-chamber 80 via the first and second side apertures 106 , 108 .
- a fuel-air mixture is ignited within the combustion pre-chamber 80 via a spark plug 48 positioned inside a cavity 82 defined by the combustion pre-chamber 80 for a first combustion stage.
- the combustion pre-chamber 80 is supported by and extends outwardly from the cylinder head 52 of the engine and into the main combustion chamber 84 of a cylinder.
- the combustion pre-chamber 80 and spark plug 48 are offset from a central axis 66 of the cylinder.
- Exhaust gases are vented from within the combustion pre-chamber 80 into the main combustion chamber 84 via the inlet aperture 100 , outlet aperture 102 , and first and second side apertures 106 , 108 thereby igniting another fuel-air mixture within the main combustion chamber 84 for a second combustion stage.
- Exhaust gases or residual gases are further purged out of the combustion pre-chamber 80 and into the main combustion chamber 84 via the outlet aperture 102 during an intake stroke.
- residual gases are drawn out of the pre-chamber 80 via the outlet aperture 102 , and intake air flows from the first and second intake ports 62 , through the first and second side apertures 106 , 108 , and into the pre-chamber 80 .
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Abstract
An internal combustion engine has a cylinder head having a cylinder roof defining first and second intake ports. The cylinder head supports a spark plug positioned between a central axis of the cylinder roof and a fuel injector. A combustion pre-chamber is connected to and extends outwardly from the roof. The pre-chamber encapsulates the spark plug, and is offset from the central axis and positioned between the central axis and the first and second intake ports. The pre-chamber defines an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defines first and second side apertures. Each side aperture is positioned adjacent to a respective one of the first and second intake ports. A method of operating an engine having a pre-chamber is also provided.
Description
- Various embodiments relate to an internal combustion engine with a combustion pre-chamber.
- Internal combustion engines may be provided with a combustion pre-chamber positioned within the cylinder, with a two-stage combustion process from the pre-chamber and into the main combustion chamber of the cylinder.
- According to an embodiment, an internal combustion engine is provided with a cylinder head having a cylinder roof defining first and second intake ports. The cylinder head supports a spark plug positioned between a central axis of the cylinder roof and a fuel injector. The cylinder head has a combustion pre-chamber connected to and extends outwardly from the roof of the cylinder. The pre-chamber encapsulates the spark plug, and is offset from the central axis and positioned between the central axis and the first and second intake ports. The pre-chamber defines an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defines first and second side apertures. Each side aperture is positioned adjacent to a respective one of the first and second intake ports.
- According to another embodiment, a method for operating an engine is provided. A fuel-air mixture is ignited within a combustion pre-chamber via a spark plug positioned inside a cavity defined by the combustion pre-chamber. The combustion pre-chamber is supported by and extends outwardly from a cylinder head of the engine and into a main combustion chamber of a cylinder. The combustion pre-chamber and spark plug are offset from a central axis of the cylinder. Exhaust gases are vented from within the combustion pre-chamber to the main combustion chamber via an inlet aperture, an outlet aperture, a first side aperture, and a second side aperture defined by the pre-chamber thereby igniting another fuel-air mixture within the main combustion chamber. Exhaust gases are purged from within the combustion pre-chamber via the outlet aperture into the main combustion chamber during an intake stroke by flowing intake air flow from first and second intake valves into the pre-chamber via the first and second side apertures.
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FIG. 1 illustrates a schematic of an internal combustion engine capable of implementing the disclosed embodiments; -
FIG. 2 illustrates a schematic view of a combustion pre-chamber and a roof of a cylinder head according to an embodiment; -
FIG. 3 illustrates a side schematic view of the combustion pre-chamber ofFIG. 2 ; -
FIG. 4 illustrates a schematic view of the combustion pre-chamber and roof ofFIG. 2 taken along the A-A section line during an injection process; -
FIG. 5 illustrates a schematic view of the combustion pre-chamber and roof ofFIG. 2 taken along the B-B section line during the injection process ofFIG. 4 ; and -
FIG. 6 illustrates a schematic view of the combustion pre-chamber and roof ofFIG. 2 taken along the B-B section line during an intake stroke and with the intake valves opened. - As required, detailed embodiments of the present disclosure are provided herein; however, it is to be understood that the disclosed embodiments are merely examples, and may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure and invention.
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FIG. 1 illustrates a schematic of aninternal combustion engine 20. Theengine 20 has a plurality ofcylinders 22, and one cylinder is illustrated. Thecylinder 22 is formed bycylinder walls 32 andpiston 34. Thepiston 34 is connected to acrankshaft 36. Thecylinder 22 is in fluid communication with theintake manifold 38 and theexhaust manifold 40. One ormore intake valves 42 controls flow from theintake manifold 38 into the combustion chamber. One ormore exhaust valves 44 controls flow from the combustion chamber to theexhaust manifold 40. The intake andexhaust valves intake valve 42 andexhaust valve 44 are described in greater detail below. - A
fuel injector 46 delivers fuel from a fuel system directly into thecylinder 22 such that the engine is a direct injection engine. A low pressure or high pressure fuel injection system may be used with theengine 20. An ignition system includes aspark plug 48 that is controlled to provide energy in the form of a spark to ignite a fuel air mixture in the combustion chamber. Thespark plug 48 may be located in various positions within thecylinder 22. - The
engine 20 includes a controller and various sensors configured to provide signals to the controller for use in controlling the air and fuel delivery to the engine, the ignition timing, valve timing, the power and torque output from the engine, and the like. Engine sensors may include, but are not limited to, an oxygen sensor in theexhaust manifold 40, an engine coolant temperature, an accelerator pedal position sensor, an engine manifold pressure (MAP) sensor, an engine position sensor for crankshaft position, an air mass sensor in theintake manifold 38, a throttle position sensor, and the like. - In some embodiments, the
engine 20 is used as the sole prime mover in a vehicle, such as a conventional vehicle, or a stop-start vehicle. In other embodiments, the engine may be used in a hybrid vehicle where an additional prime mover, such as an electric machine, is available to provide additional power to propel the vehicle. - Each
cylinder 22 may operate under a four-stroke cycle including an intake stroke, a compression stroke, an ignition stroke, and an exhaust stroke. In other embodiments, the engine may operate with a two-stroke cycle. Thepiston 34 position at the top of thecylinder 22 is generally known as top dead center (TDC). Thepiston 34 position at the bottom of the cylinder is generally known as bottom dead center (BDC). - During the intake stroke, the intake valve(s) 42 opens and the exhaust valve(s) 44 closes while the
piston 34 moves from the top of thecylinder 22 to the bottom of thecylinder 22 to introduce intake gases, e.g. air, from the intake manifold to the combustion chamber. Fuel may be introduced into thecylinder 22 while thepiston 34 moves down during the intake stroke. - During the compression stroke, the intake and
exhaust valves piston 34 moves from the bottom towards the top of thecylinder 22 to compress the air/fuel mixture within thecylinder 22. - The compressed air/fuel mixture is then ignited within the
cylinder 22. In theengine 20 shown, the fuel is injected into thecylinder 22 and is then ignited usingspark plug 48. Fuel injection and ignition according to the present disclosure is described below in greater detail. - During the power stroke, also known as the expansion stroke, the ignited fuel-air mixture in the
cylinder 22 expands, thereby causing thepiston 34 to move from the top of thecylinder 22 to the bottom of thecylinder 22. The movement of thepiston 34 causes a corresponding movement incrankshaft 36 and provides for a mechanical torque output from theengine 20. - During the exhaust stroke, the intake valve(s) 42 remains closed, and the exhaust valve(s) 44 opens. The
piston 34 moves from the bottom of the cylinder to the top of thecylinder 22 to remove the exhaust gases and combustion products from thecylinder 22 by reducing the volume of thecylinder 22. The exhaust gases flow from thecylinder 22 to theexhaust manifold 40 and to an aftertreatment system such as a catalytic converter. - The intake and
exhaust valves - The
engine 20 has anengine cylinder block 50 and acylinder head 52. Ahead gasket 54 is interposed between thecylinder block 50 and thecylinder head 52 to seal thecylinders 22. - The cylinder head defines a
roof 60. Theroof 60 cooperates with theblock 50 to define thecylinder 22. - The
roof 60 of thecylinder head 52 defines at least oneintake air port 62 that receives an associatedintake valve 42. Theintake air port 62 provides a passage for flow of intake air or intake gases from theintake manifold 38 to arespective cylinder 22. Intake air may include outside or environmental air, may include fuel mixed therein, and may also be mixed with exhaust gases from an exhaust gas recirculation system, etc. - The roof of the
cylinder head 52 defines at least oneexhaust gas port 64 that receives an associatedexhaust valve 44. Theexhaust gas port 64 provides a passage for flow of exhaust gases from eachcylinder 22 to theexhaust manifold 40. - The intake port(s) 62 and exhaust port(s) 64 may be offset from the
central axis 66. Likewise, thespark plug assembly 48 may be offset from thecentral axis 66, and in one example, may be adjacent to the intake port(s) 62 as further described below. Thefuel injector 46 may likewise be offset from thecentral axis 66. - The
engine 20 may be provided with acombustion pre-chamber 80. The combustion pre-chamber 80 may be used to increase combustion stability in theengine 20, for example, when used with anengine 20 having exhaust gas recirculation (EGR). EGR may be used to increase engine thermal efficiencies; however, EGR may reduce combustion stability in theengine 20, as well as result in increased levels of noise, vibration, and harshness (NVH). Conventionally, a combustion pre-chamber is provided in the center of the cylinder, such that there may be challenges in purging residual gases after a combustion event within the pre-chamber, e.g. purging exhaust gases or combustion byproducts from the combustion pre-chamber. When residual gases, combustion byproducts, or exhaust gases are insufficiently purged from a combustion pre-chamber, there may be associated challenges with the next ignition cycle or starting the next combustion event within the pre-chamber, e.g. a possible misfire event. These challenges may increase when using EGR, running the engine in a fuel lean state, or the like. -
FIGS. 2-6 illustrate acombustion pre-chamber 80 according to the present disclosure. In one example, the combustion pre-chamber may be used with theengine 20 as described above. Thecombustion pre-chamber 80 provides for increased purging of the residual gases or exhaust gases within the pre-chamber. For simplicity, elements that are the same as or similar to those described above with respect toFIG. 1 are given the same reference number. - The pre-chamber 80 may be formed as a hollow body defining a cavity. The pre-chamber 80 is formed with a continuous side wall that extends outwardly from the
roof 60 of the cylinder head, and a lower wall that is spaced apart from the roof. In one example, and as shown, the pre-chamber 80 may be formed with the side wall and lower wall blended together in a continuous curve. In a further example, the pre-chamber 80 may be formed with a continuous curved wall. The continuous curved wall may have a constant radius of curvature such that the pre-chamber 80 is formed as a section or portion of a sphere. For example, the pre-chamber 80 may be formed as a spherical dome from a majority section of a sphere as shown schematically inFIG. 3 . According to one non-limiting example, the pre-chamber 80 is formed as a spherical dome from between 60-85% of a sphere, or between 60-75% of a sphere. In another example, the continuous curved wall has a varying radius of curvature. - The pre-chamber 80 defines a
cavity 82 therein, such that the volume of thecylinder 22 is divided into the pre-chamber 80 and amain combustion chamber 84. The main combustion chamber is the region of thecylinder 22 that is outside the pre-chamber 80. - The
spark plug assembly 48 is offset from thecentral axis 66 of the cylinder, and is positioned in a region of thecylinder roof 60 that is between thecentral axis 66 and the first andsecond intake ports 62. Thespark plug assembly 48 is positioned between thefuel injector 46 and thecentral axis 66. Thefuel injector 46 is therefore also offset from thecentral axis 66, and may be positioned within thecylinder 22 such that it is adjacent to theintake ports 62, and spaced apart from theexhaust ports 64. - The pre-chamber 80 is connected to the
roof 60 of the cylinder head such that thespark plug assembly 48 is received within thecavity 82 defined by the pre-chamber 80. The pre-chamber 80 may encapsulate thespark plug assembly 48. The pre-chamber 80 is therefore offset from thecentral axis 66, and is positioned between the first andsecond intake ports 62, and is positioned between thecentral axis 66 and the first andsecond intake ports 62 as shown inFIG. 2 . - According to one example, and as shown in
FIG. 2 , thecombustion pre-chamber 80 is positioned between thecentral axis 66 of the cylinder and afirst line 90 extending through the center axes of bothintake valves 42 or centers of theintake ports 60. - In a further example, and as shown, the
combustion pre-chamber 80 is positioned such that an acute angle α is formed between thefirst line 90 and asecond line 92 extending through the center axis of thefirst intake valve 42 orintake port 60 and thecentral axis 66 of the combustion pre-chamber. Thecombustion pre-chamber 80 is also positioned such that an acute angle β is formed between thefirst line 90 and athird line 94 extending through the center axis of thesecond intake valve 42 orintake port 62 and thecentral axis 66 of the combustion pre-chamber. Each of the acute angles α, β may be in the range of 15-20 degrees, although other acute angle ranges are also contemplated. Furthermore, and in some examples, the two acute angles α, β may be the same as one another. - The pre-chamber 80 defines an
inlet aperture 100 and anoutlet aperture 102. Theinlet aperture 100 and theoutlet aperture 102 may be opposite to one another on the pre-chamber 80. Theinlet aperture 100 andoutlet aperture 102 may be positioned along aspray streamline 104 of thefuel injector 46, with theinlet aperture 100 positioned between thefuel injector 46 and theoutlet aperture 102. Theoutlet aperture 102 may be positioned to face thecentral axis 66, or may be positioned to face generally towards the first andsecond exhaust ports 64, or the region of the roof defining the first andsecond exhaust ports 64. Note that thefuel injector 46 may have multiple spray streamlines, with only thespray streamline 104 directed to the pre-chamber 80 being shown. The remaining spray streamlines may direct fuel into themain combustion chamber 84 during an injection event. - The pre-chamber 80 also defines a
first side aperture 106 and asecond side aperture 108. In the example shown, the pre-chamber 80 has only onefirst side aperture 106 and only onesecond side aperture 108, such that the pre-chamber 80 has only fourapertures engine 20. In other examples, the pre-chamber 80 may have two or morefirst side apertures 106 and two or moresecond side apertures 108. - The
first side aperture 106 is positioned adjacent to thefirst intake port 62, and thesecond side aperture 108 is positioned adjacent to thesecond intake port 62. The spray streamline 104 from the fuel injector therefore extends through the pre-chamber 80 and between the first andsecond side apertures - According to one example, the cross-sectional area of the
outlet aperture 102 may be greater than a cross-sectional area of theinlet aperture 100. Furthermore, the cross-sectional area of theoutlet aperture 102 may be greater than a cross-sectional area of thefirst side aperture 106 and greater than a cross-sectional area of thesecond side aperture 108. The cross-sectional area of theinlet aperture 100 may be less than a cross-sectional area of thefirst side aperture 106 and also less than a cross-sectional area of thesecond side aperture 108. The first andsecond side apertures inlet aperture 100 has a cross-sectional area of 1.2 mm2, the first andsecond side apertures outlet aperture 102 has a cross-sectional area of 3 mm2. - A centerline of the
fuel injector 46 may be oriented at an acute angle relative to thecentral axis 66 of the cylinder, as shown inFIGS. 3 and 4 . In use, aspray 104 of fuel from thefuel injector 46 is directed towards the pre-chamber 80, and thisspray 104 of fuel enters the pre-chamber via theinlet aperture 100. The remainder of fuel injected by thefuel injector 46 is directed into themain combustion chamber 84. Theinlet aperture 100 is therefore aligned or generally aligned with thespray 104 streamline from the fuel injector. - The
inlet aperture 100 therefore receives aspray 104 of fuel with a first portion of fuel from thefuel injector 46 during a fuel injection process. - A second portion of fuel from the
spray 104 of fuel exits the pre-chamber 80 via theoutlet aperture 102 during the fuel injection process, with the second portion being less than the first portion. Thespray 104 of fuel therefore has some fuel that passes through the pre-chamber 80 and back into themain chamber 84. A remainder of the fuel remains in thecavity 82 of the pre-chamber 80, and this amount may be equivalent to the first portion of fuel minus the second portion of fuel in thespray 104. In one example, only 3-5% by volume of the total fuel injected into the pre-chamber 80 remains in the pre-chamber 80 after the injection process and prior to an ignition event. - The high velocity of the
spray 104 across the pre-chamber 80, e.g. from theinlet aperture 100 to theoutlet aperture 102, creates a vacuum of low pressure region within the pre-chamber 80 compared to themain chamber 84. The local pressure within the pre-chamber 80 is therefore less than the local pressure in themain combustion chamber 84. As such, thespray 104 of fuel may push residual gases out of the pre-chamber 80 via theoutlet aperture 102. Furthermore, the low pressure created in the pre-chamber 80 by thespray 104 of fuel therethrough causes intake air or gases within themain combustion chamber 84 to flow into the pre-chamber 80 via the first andsecond side apertures FIG. 4 illustrates the injection process with aspray 104 of fuel through the pre-chamber 80, andFIG. 5 illustrates intake air or gas in themain chamber 84 being drawn into the pre-chamber 80 via theside apertures - The
spark plug assembly 48 may then be activated or sparked to ignite the fuel-air mixture within the pre-chamber 80. As the end of thespark plug assembly 48 is located within the pre-chamber 80, the fuel-air mixture within the pre-chamber 80 ignites prior to any combustion event in themain combustion chamber 84. - The fuel-air charge in the pre-chamber 80 is ignited by the
spark plug assembly 48 and the flame propagates across and within thecavity 82 of the pre-chamber 80. With the combustion event in the pre-chamber 80, hot exhaust gases or combustion byproduct gases in the pre-chamber 80 vent or exit out of the pre-chamber 80 and into themain combustion chamber 84 via theinlet aperture 100,outlet aperture 102, andside apertures main combustion chamber 84. The positioning of theapertures main combustion chamber 84 in the cylinder to provide multiple ignition points of the fuel-air charge in themain combustion chamber 84. - The pre-chamber 80 therefore provides for a two-stage combustion process within the
cylinder 22. The first stage is provided by thespark plug 48 ignition and a combustion event in the pre-chamber 80. The second stage is provided by ignition in themain chamber 84 caused by the exhaust gases from the pre-chamber 80 flowing into and igniting the fuel-air mixture in themain chamber 84. - The
outlet aperture 102 may have a larger cross-sectional area than theinlet aperture 100 both to allow for and control the exit of a portion of thefuel spray 104 from the pre-chamber, as well as to direct a larger proportion of hot exhaust gases from the pre-chamber 80, towards theexhaust port 64 side of thecylinder 22 based on the offset location of the pre-chamber 80 in the cylinder. Thelarger outlet aperture 102 cross-sectional area therefore provides for a control over the flow of hot exhaust gases from the pre-chamber 80 into themain combustion chamber 84, and improved ignition of the fuel-air charge in themain combustion chamber 84 in theexhaust port 64 region of themain combustion chamber 84 and cylinder. - The cross-sectional areas of the
inlet aperture 100,outlet aperture 102, andside apertures main combustion chamber 84. The smaller the cross-sectional area, the lower the penetration distance for the flow of exhaust gases from the pre-chamber 80 into themain combustion chamber 84. The cross-section areas of thepre-chamber apertures cylinder 22 wall that the respective aperture faces, with the cross-sectional area increasing in size with increased distance to thecylinder 22 side wall. - The pre-chamber 80 is further purged during the intake stroke and with the
intake valves 42 opened, as shown inFIG. 6 . During the intake stroke, the piston moves down and away from the cylinder head, which creates a vacuum or low pressure within thecylinder 22 and draws intake air into the cylinder via theintake ports 62 and openedintake valves 42. Note that intake air may include exhaust gases recirculated from the engine exhaust (EGR) as well as outside air. During the intake stroke and based on the low pressure in themain combustion chamber 84 due to the movement of the piston, residual gases or combustion byproducts are drawn out of the pre-chamber 80 via theoutlet aperture 102, and intake air is drawn into the pre-chamber 80 from theintake ports 62 via the first andsecond side apertures FIG. 6 . - The first and
second side apertures second intake ports 62 to aid in the flow of intake air into the pre-chamber 80. In further examples, the first andsecond side apertures roof 60 of the cylinder and the bottom or face of the associatedintake valve 42 with theintake valve 42 in a fully open position, as shown inFIG. 6 . This intermediate position for theside apertures intake ports 62 into the pre-chamber 80 as well as purge combustion byproducts from the prior combustion cycle from the pre-chamber 80 during the intake stroke. - The pre-chamber 80 according to the present disclosure therefore provides for control over an amount of fuel within the pre-chamber 80 at an ignition event, and also allows for a multi-stage purge process of the pre-chamber 80 to remove combusted residual gases from the pre-chamber 80 and provide a charge of intake air into the pre-chamber 80 prior to a subsequent ignition event. This may result in a more robust and stable combustion event for the
engine 20, and may be used with engines that are being operated at a high dilution or fuel lean condition, or with EGR. - According to various embodiments, a method for operating an engine is provided. The engine may be the
engine 20 as described above. Elements that are the same as or similar to those described above are given the same reference number for simplicity. - An
engine 20 is provided and has acylinder head 52 with a pre-chamber 80. In one example, thecylinder head 52 andpre-chamber 80 are formed together as an integral component during a casting process. In another example, thecylinder head 52 andpre-chamber 80 may be formed as separate components, with the pre-chamber machined to the desired size and shape and then attached to theroof 60 of the cylinder via a welding process, via fasteners, or the like. - The pre-chamber 80 may be formed with or may have
apertures inlet aperture 100, anoutlet aperture 102, and first andsecond side apertures second side apertures roof 60 of the cylinder and a face of thefirst intake valve 42 when the first intake valve is in a fully open position. - Fuel is injected into the
cylinder 22 using afuel injector 46. Aspray 104 of fuel from the fuel injector is received by the pre-chamber 80 via theinlet aperture 100. - Exhaust gases or residual gases are purged in a first purging stage from the pre-chamber 80 while injecting fuel into the
cylinder 22. During a compression stroke and/or during the injection process, a portion of thespray 104 of fuel flows out of the pre-chamber 80 via theoutlet aperture 102 and thereby pushes residual gases out of the pre-chamber 80 via theoutlet aperture 102 while drawing air from themain combustion chamber 84 into the pre-chamber 80 via the first andsecond side apertures - A fuel-air mixture is ignited within the
combustion pre-chamber 80 via aspark plug 48 positioned inside acavity 82 defined by the combustion pre-chamber 80 for a first combustion stage. Thecombustion pre-chamber 80 is supported by and extends outwardly from thecylinder head 52 of the engine and into themain combustion chamber 84 of a cylinder. The combustion pre-chamber 80 andspark plug 48 are offset from acentral axis 66 of the cylinder. - Exhaust gases are vented from within the
combustion pre-chamber 80 into themain combustion chamber 84 via theinlet aperture 100,outlet aperture 102, and first andsecond side apertures main combustion chamber 84 for a second combustion stage. - Exhaust gases or residual gases are further purged out of the
combustion pre-chamber 80 and into themain combustion chamber 84 via theoutlet aperture 102 during an intake stroke. During the intake stroke and with theintake valves 42 opened, residual gases are drawn out of the pre-chamber 80 via theoutlet aperture 102, and intake air flows from the first andsecond intake ports 62, through the first andsecond side apertures - While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosure or invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
Claims (21)
1. An internal combustion engine comprising:
a cylinder head having a cylinder roof defining first and second intake ports, and supporting a spark plug positioned between a central axis of the cylinder roof and a fuel injector, the cylinder head having a combustion pre-chamber extending outwardly from the roof, the pre-chamber encapsulating the spark plug, the pre-chamber offset from the central axis and positioned between the central axis and the first and second intake ports, the pre-chamber defining an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defining first and second side apertures, each side aperture positioned adjacent to a respective one of the first and second intake ports.
2. The engine of claim 1 wherein the spray streamline extends between the first and second side apertures.
3. The engine of claim 1 wherein the outlet aperture is positioned to face towards first and second exhaust ports defined by the cylinder roof.
4. An internal combustion engine comprising:
a cylinder head having a cylinder roof defining first and second intake ports, and supporting a spark plug positioned between a central axis of the cylinder roof and a fuel injector, the cylinder head having a combustion pre-chamber extending outwardly from the roof, the pre-chamber encapsulating the spark plug, the pre-chamber offset from the central axis and positioned between the central axis and the first and second intake ports, the pre-chamber defining an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defining first and second side apertures, each side aperture positioned adjacent to a respective one of the first and second intake ports;
wherein a cross-sectional area of the outlet aperture is greater than a cross-sectional area of the inlet aperture.
5. The engine of claim 1 wherein a cross-sectional area of the outlet aperture is greater than a cross-sectional area of the first side aperture and greater than a cross-sectional area of the second side aperture.
6. The engine of claim 5 wherein a cross-sectional area of the outlet aperture is greater than a cross-sectional area of the first side aperture, and wherein the cross-sectional area of the first side aperture is greater than a cross-sectional area of the inlet aperture.
7. The engine of claim 1 wherein the fuel injector is oriented at an acute angle relative to the central axis.
8. The engine of claim 1 wherein the combustion pre-chamber is formed as a spherical dome from a majority section of a sphere.
9. The engine of claim 1 wherein the inlet aperture is positioned to receive a first portion of fuel from the fuel injector into the pre-chamber during a fuel injection, and wherein a second portion of fuel from the fuel injector exits the pre-chamber via the outlet aperture during the fuel injection, the second portion being less than the first portion.
10. The engine of claim 1 wherein the combustion pre-chamber is positioned between the central axis and a first line extending through first and second centers of the first and second intake ports, respectively.
11. The engine of claim 10 wherein the combustion pre-chamber is positioned such that an acute angle is formed between the first line and a second line extending through the first center of the first intake port and a center of the combustion pre-chamber.
12. The engine of claim 11 wherein the acute angle is between sixty and seventy-five degrees.
13. The engine of claim 1 further comprising a cylinder block defining a cylinder sized to receive a piston, the cylinder block cooperating with the cylinder head such that the cylinder and cylinder roof cooperate to define a main combustion chamber.
14. A method for operating an engine, the method comprising:
igniting a fuel-air mixture within a combustion pre-chamber via a spark plug positioned inside a cavity defined by the combustion pre-chamber, the combustion pre-chamber supported by and extending outwardly from a cylinder head of the engine and into a main combustion chamber of a cylinder, the combustion pre-chamber and spark plug being offset from a central axis of the cylinder, with the pre-chamber positioned between the central axis, the first intake valve, and the second intake valve;
venting exhaust gases from within the combustion pre-chamber to the main combustion chamber via an inlet aperture, an outlet aperture, a first side aperture, and a second side aperture defined by the pre-chamber thereby igniting another fuel-air mixture within the main combustion chamber; and
purging exhaust gases from within the combustion pre-chamber via the outlet aperture into the main combustion chamber during an intake stroke by flowing intake air flow from first and second intake valves into the pre-chamber via the first and second side apertures.
15. The method of claim 14 further comprising injecting fuel using a fuel injector, wherein a spray of fuel from the fuel injector is received by the pre-chamber via the inlet aperture, and wherein the spark plug is positioned between the central axis and the fuel injector.
16. The method of claim 15 further comprising purging exhaust gases from the pre-chamber while injecting fuel, wherein a portion of the spray of fuel flows out of the pre-chamber via the outlet aperture thereby drawing air from the main combustion chamber into the pre-chamber via the first and second side apertures during a compression stroke.
17. (canceled)
18. The method of claim 14 further comprising forming the first and second side apertures in the pre-chamber such that the first and second side apertures are positioned between a roof of the cylinder and a face of the first intake valve when the first intake valve is in a fully open position.
19. The method of claim 14 wherein the combustion pre-chamber is formed by a machining process, and wherein the machined combustion pre-chamber is connected to the cylinder head via welding.
20. The method of claim 14 wherein the combustion pre-chamber is integrally formed with the cylinder head during a casting process.
21. The method of claim 14 wherein the cross-sectional area of the outlet aperture is greater than at least one of a cross-sectional area of the inlet aperture and a cross-sectional area of the first side aperture.
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DE102021126450.2A DE102021126450A1 (en) | 2020-10-19 | 2021-10-12 | PRE-COMBUSTION CHAMBER FOR AN INTERNAL ENGINE |
CN202111212652.8A CN114382586A (en) | 2020-10-19 | 2021-10-18 | Combustion prechamber for an internal combustion engine |
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US4072134A (en) * | 1974-11-13 | 1978-02-07 | Toyota Jidosha Kogyo Kabushiki Kaisha | Apparatus for supplying rich air/fuel mixture in an internal combustion engine |
US4072136A (en) * | 1974-11-13 | 1978-02-07 | Toyota Jidosha Kogyo Kabushiki Kaisha | Apparatus for supplying rich air/fuel mixture in an internal combustion engine |
US4085713A (en) * | 1973-02-27 | 1978-04-25 | Nippon Soken, Inc. | Torch ignition internal combustion engine |
US5778849A (en) * | 1997-05-05 | 1998-07-14 | Chrysler Corporation | Insulated precombustion chamber |
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JP6565952B2 (en) | 2017-02-13 | 2019-08-28 | トヨタ自動車株式会社 | Internal combustion engine |
WO2018213264A2 (en) | 2017-05-15 | 2018-11-22 | Cummins Inc. | Combustion pre-chamber assemblies for an internal combustion engine |
US10337397B2 (en) | 2017-06-14 | 2019-07-02 | Ford Global Technologies, Llc | Pre-chamber ignition system |
DE102017009235A1 (en) | 2017-10-04 | 2019-04-04 | Daimler Ag | Method for operating an internal combustion engine for a motor vehicle |
DE102018007093A1 (en) | 2018-09-07 | 2020-03-12 | Daimler Ag | Prechamber spark plug for a combustion chamber of an internal combustion engine, in particular a motor vehicle |
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US4085713A (en) * | 1973-02-27 | 1978-04-25 | Nippon Soken, Inc. | Torch ignition internal combustion engine |
US4072134A (en) * | 1974-11-13 | 1978-02-07 | Toyota Jidosha Kogyo Kabushiki Kaisha | Apparatus for supplying rich air/fuel mixture in an internal combustion engine |
US4072136A (en) * | 1974-11-13 | 1978-02-07 | Toyota Jidosha Kogyo Kabushiki Kaisha | Apparatus for supplying rich air/fuel mixture in an internal combustion engine |
US5778849A (en) * | 1997-05-05 | 1998-07-14 | Chrysler Corporation | Insulated precombustion chamber |
US20070089703A1 (en) * | 2005-10-24 | 2007-04-26 | Nissan Motor Co., Ltd. | Internal combustion engine with auxiliary combustion chamber |
US20210003066A1 (en) * | 2019-07-03 | 2021-01-07 | Ford Global Technologies, Llc | Methods and systems for a prechamber |
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US11306648B1 (en) | 2022-04-19 |
DE102021126450A1 (en) | 2022-05-05 |
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