Internal combustion engine with precombustion chamber

Abstract

The invention relates to an internal combustion engine with a pre-combustion chamber. The internal combustion engine, preferably a large two-stroke internal combustion engine, comprises: a cylinder head (4) and a cylinder (10) with a cylinder liner (8); at least one piston (9) which is reciprocatingly received in a cylinder volume (5) formed in the cylinder (10). The internal combustion engine further comprises: at least one pre-combustion chamber (2), which is preferably arranged in the cylinder head (4), the pre-combustion chamber volume (11) of the pre-combustion chamber (2) being fluidically connected to the cylinder volume (5) for igniting a gas / air mixture; and at least one exhaust valve (6), which is arranged in the cylinder head (4) for controlling the flow of gas from the cylinder volume (5) to an exhaust pipe (7) of the internal combustion engine (100). The pre-combustion chamber (2) comprises an outlet (1) which can be fluidically connected to the exhaust pipe (7).

Description

Technical Field

[0001] The invention relates to an internal combustion engine comprising a precombustion chamber, a method of operating an internal combustion engine having a precombustion chamber, a precombustion chamber and a computer program. Background Art

[0002] Large bore, lean working gas engines typically include a pre-chamber assembly to ensure ignition in the engine. The pre-chamber includes a pre-chamber volume in fluid communication with the main combustion chamber of the cylinder via one or more small orifices.

[0003] The present invention preferably relates to an internal combustion engine having a cylinder having an internal diameter of at least 200 mm, such as a large marine or ship engine or a stationary engine. The engine is preferably a two-stroke engine or a two-stroke crosshead engine. The engine may be a gas engine, a dual-fuel or a multi-fuel engine. The engine speed is preferably less than 800 RPM (four-stroke), more preferably less than 200 RPM (two-stroke), which is a hallmark of a slow-speed engine.

[0004] Pre-chambers are particularly used in so-called lean-burn engines, which require a powerful ignition source. In these cases, they are used to provide the high energy required to ignite the lean gas mixture in the main combustion chamber. In the pre-chamber, the lean basic air-gas mixture originating from the main combustion chamber can be ignited either by injecting a suitable fuel that reacts in excess air and ignites when certain pressure and temperature conditions are exceeded, or by means of a glow plug or spark plug in combination with a partially stoichiometric air-gas mixture that can be achieved by adding a suitable amount of gas directly to the pre-chamber.

[0005] The shape of the pre-chamber depends on the actual ignition method. Pilot fuel ignition with or without a glow plug can provide higher ignition energy than conventional spark pre-chamber ignition systems.

[0006] The requirement is generally to quickly and reproducibly mix the basic air-gas fuel mixture introduced into the pre-chamber and the pilot fuel to be injected eventually.

[0007] The pre-chamber must be prepared for each new cycle. Residues left in the pre-chamber from the previous cycle can cause the temperature to rise and can promote undesirable auto-ignition.

[0008] Although a number of pre-chamber arrangements are known, they are not able to simultaneously meet the above requirements.

[0009] It is therefore an object of the present invention to avoid the disadvantages of the prior art and to provide an internal combustion engine, a method of using an internal combustion engine and a precombustion chamber, wherein the precombustion chamber can be operated optimally with respect to the combustion cycle. Summary of the Invention

[0010] This object is achieved by an internal combustion engine according to the invention, a method for operating an internal combustion engine, a precombustion chamber and a computer program according to the invention.

[0011] The internal combustion engine is preferably a large two-stroke internal combustion engine.

[0012] The internal combustion engine comprises a cylinder head and at least one cylinder having a cylinder liner. At least one piston is reciprocatingly received in a cylinder volume formed in the cylinder.

[0013] Typically, the piston is connected to a crankshaft and is arranged to reciprocate between top dead center (TDC) and bottom dead center (BDC) during engine operation.

[0014] At least one exhaust valve is arranged in the cylinder head to control the flow of gas from the cylinder volume to an exhaust pipe of the internal combustion engine.

[0015] The internal combustion engine comprises at least one pre-combustion chamber for igniting a gas / air mixture.

[0016] The ratio of the volume of the pre-chamber to the compressed volume of the combustion cylinder may be between 0.1-1%, preferably between 0.1-0.8%, most preferably between 0.1-0.5%.

[0017] At least one pre-combustion chamber having a pre-combustion chamber volume is fluidically connected to the cylinder volume. The pre-combustion chamber may be arranged in the cylinder head.

[0018] The precombustion chamber includes at least one outlet fluidically connectable to the exhaust pipe, and the precombustion chamber includes at least one outlet valve to control the flow of exhaust gas from the precombustion chamber to the exhaust pipe. If the precombustion chamber includes more than one outlet, each outlet can be controlled by a valve. The outlet valve may be slidably received in the precombustion chamber and may cooperate with an outlet valve seat provided in a wall of the precombustion chamber.

[0019] The outlet of the pre-chamber, in particular the valve seat of the outlet valve, may be arranged spaced apart from an orifice or duct for allowing fluid connection to the cylinder volume.The outlet may be arranged opposite the orifice or duct.

[0020] The internal combustion engine may include at least one feeder pipe fluidly connected to the exhaust pipe and fluidly connectable to the outlet of the pre-combustion chamber.

[0021] The pre-combustion chamber may be fluidically connected to the exhaust pipe via one or more branch pipes. The branch pipes allow the pre-combustion chamber to be arranged spaced apart from the exhaust valve.

[0022] The exhaust valve may be centrally located in the cylinder head. A pre-combustion chamber may be located in the cylinder head, with the pre-combustion chamber positioned closer to the cylinder liner than to the radial center of the cylinder. Thus, the pre-combustion chamber may be eccentrically located relative to the main axis of the combustion cylinder.

[0023] Alternatively, the exhaust valve may be arranged eccentrically relative to the main axis of the combustion cylinder.

[0024] Preferably, the internal combustion engine comprises exactly one pre-combustion chamber having one or more outlets.

[0025] The pre-combustion chamber may be arranged around the exhaust pipe and may be arranged in an annular shape relative to the exhaust valve.

[0026] The internal combustion engine may comprise more than one pre-combustion chamber, preferably all pre-combustion chambers having an outlet and an outlet valve.

[0027] Preferably, the cylinder comprises an air inlet port arranged in the cylinder liner. In particular, the cylinder comprises a scavenging port arranged in the cylinder liner. The internal combustion engine may be a longitudinally flushed two-stroke engine.

[0028] The pre-combustion chamber may comprise an ignition device for igniting the gas-air mixture, preferably the ignition device is a spark plug extending into an ignition chamber of the pre-combustion chamber.

[0029] The pre-combustion chamber may include an injection device for injecting a suitable pilot fuel, in particular a fuel nozzle. By injecting the pilot fuel, ignition in the cylinder can be achieved at a defined point in the combustion cycle. The pilot fuel may be gas or diesel. The pilot fuel is preferably a liquid fuel.

[0030] The internal combustion engine may include a first setting unit for setting an outlet valve. The first setting unit is configured to actuate the outlet valve. The outlet valve may be actuated by compressed air, hydraulically, or electrically. The first setting unit may also be adapted to set a plurality of outlet valves, for example, a plurality of outlet valves for a single precombustion chamber and / or a plurality of outlet valves for different precombustion chambers.

[0031] Preferably, the internal combustion engine includes a second setting unit for setting at least one exhaust valve. The second setting unit is used to actuate the exhaust valve. The exhaust valve can be actuated by compressed air, hydraulically, or electrically. If a cylinder includes more than one exhaust valve, there can be one second setting unit for all exhaust valves, or there can be multiple second setting units, for example, one second setting unit for each exhaust valve.

[0032] Thus, the outlet valve and the exhaust valve can be actuated independently of each other.

[0033] Alternatively, actuation of the exhaust and outlet valves may be coupled such that movement of one valve causes movement of the other valve.

[0034] The setting unit may include a switch and / or a valve.

[0035] In an advantageous embodiment of the internal combustion engine, the internal combustion engine comprises a control unit for operating the outlet valve and the exhaust valve in a suitably timed sequence following the displacement of the piston.

[0036] The control unit comprises at least one output line, which is preferably connected or connectable to a first setting unit for setting the outlet valve and / or a second setting unit for setting the exhaust valve.

[0037] Preferably, the control unit comprises at least a first output line connectable or connectable to a first setting unit for setting the exhaust valve and at least a second output line connectable or connectable to a second setting unit for setting the exhaust valve.

[0038] In particular, the control unit is adapted to control said outlet valve and preferably said at least one exhaust valve.The control unit may send corresponding signals to the corresponding setting units via corresponding output lines.

[0039] The control unit may be adapted to control the outlet valve and the at least one exhaust valve so that both valves are closed during compression, combustion and expansion and when the piston passes its top dead center. The control unit may be configured to open the exhaust valve after the piston passes top dead center and while the piston moves downward.

[0040] The control unit may be configured to open the outlet valve, preferably after the exhaust valve has opened and / or after air has started to enter the cylinder, to expel any residue remaining in the pre-combustion chamber.

[0041] The control unit may be configured to close the outlet valve after the piston passes its bottom dead center and air stops entering the cylinder.Preferably, simultaneously or subsequently, the control unit may be configured to close the exhaust valve.

[0042] Preferably, the control unit is further adapted to control an air intake port in the cylinder.The internal combustion engine may comprise a setting unit for setting the air intake valve, and the control unit may comprise a further output line connectable or connectable to the setting unit for setting the air intake valve.

[0043] The object of the present invention is also achieved by a method for operating an internal combustion engine as described above. The method comprises the following steps.

[0044] During compression, combustion and expansion and when the piston passes its top dead center, at least one exhaust valve and at least one outlet valve of the pre-combustion chamber are kept closed.

[0045] During the time the piston moves downward, the exhaust valve opens, allowing exhaust gas to escape from the cylinder. After the exhaust valve opens, air can enter the cylinder. Exhaust gas is flushed out of the cylinder.

[0046] Preferably after the exhaust valve opens and / or after air begins to enter the cylinder, the outlet valve is opened to expel any residue remaining in the pre-combustion chamber.

[0047] After the piston passes its bottom dead center and air stops entering the cylinder, the outlet valve is closed and, preferably simultaneously or subsequently, the exhaust valve is closed.

[0048] The objects of the present invention are also achieved by a precombustion chamber for an internal combustion engine as described above, wherein the precombustion chamber comprises an outlet fluidically connectable to an exhaust pipe of the internal combustion engine and the precombustion chamber comprises an outlet valve to control the flow of exhaust gas from the precombustion chamber to the exhaust pipe.

[0049] The objects of the present invention are also achieved by a computer program for loading into a computer and / or running on a computer, wherein the computer program is suitable for executing the method for operating an internal combustion engine as described above, in particular, the method for operating the outlet valve and the exhaust valve in an appropriately timed sequence as the piston is displaced.

[0050] The computer program can be loaded onto a control unit of an internal combustion engine as described above and / or run on the control unit.

[0051] The computer program may be loaded onto and / or run on a central computer device of the vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Below, the present invention is further described in the embodiments with the help of the accompanying drawings:

[0053] Figure 1 shows a schematic cross-sectional view of a portion of a first example of an internal combustion engine;

[0054] Figures 2a to 2d Various positions of a valve during a combustion cycle are schematically shown in a cross-sectional view of a portion of an internal combustion engine;

[0055] Figure 3 The valve settings during the combustion cycle are schematically shown;

[0056] Figure 4 shows a schematic diagram of an internal combustion engine;

[0057] Figure 5 shows a schematic cross-sectional view of a portion of a second example of an internal combustion engine;

[0058] Figure 6 shows a schematic cross-sectional view of a portion of a third example of an internal combustion engine;

[0059] Figure 7 A schematic cross-sectional view of a portion of a fourth example of an internal combustion engine is shown. DETAILED DESCRIPTION

[0060] Figure 1 A schematic cross-sectional view of a portion of a first example of an internal combustion engine 100 is shown.

[0061] The internal combustion engine 100 comprises a cylinder head 4 and a cylinder 10 having a cylinder liner 8. A piston 9 moves upward and downward in a cylinder volume 5 formed in the cylinder 10.

[0062] Scavenging ports 18 are arranged in the cylinder liner 8. When the piston 9 is at its bottom dead center as shown in the figure, air can enter the cylinder 10.

[0063] A fuel inlet not shown in the figure may also be arranged in the cylinder liner.

[0064] An exhaust valve 6 is arranged in the cylinder head 4 to control the flow of gas from the cylinder volume 5 to an exhaust pipe 7 of the internal combustion engine 100 .

[0065] The exhaust pipe 7 may guide the exhaust gas to an exhaust manifold and / or a turbine of a turbocharger (not shown).

[0066] The internal combustion engine 100 further comprises a pre-combustion chamber 2 arranged in the cylinder head 4. A pre-combustion chamber duct 19 fluidically connects the volume 11 of the pre-combustion chamber 2 with the cylinder volume 5.

[0067] The pre-combustion chamber 2 comprises an outlet 1 which is fluidically connectable to an exhaust pipe 7. An outlet valve 3 is arranged in the outlet 1. The outlet valve 3 is slidably received in the pre-combustion chamber 2 and cooperates with an outlet valve seat 12 provided in the wall of the pre-combustion chamber 2.

[0068] The outlet valve 3 controls the fluid communication between the pre-chamber volume 11 and a branch line 13 which directs any fluid from the pre-chamber volume 11 to the exhaust pipe 7 .

[0069] Figures 2a to 2d The various positions of the valves 6 , 3 during a combustion cycle are schematically shown in a cross-sectional view of a portion of the internal combustion engine 100 .

[0070] When Figure 2a When the piston 9 passes its top dead center, the exhaust valve 6 and the outlet valve 3 are closed.

[0071] When Figure 2b When the piston 9 shown moves further downward, the exhaust valve 6 opens and the residue begins to leave the cylinder volume 5. The scavenging port (not shown in the figure) opens and fresh air begins to enter the cylinder volume 5.

[0072] Afterwards, if Figure 2c As shown, outlet valve 3 is also open. Exhaust gas leaves through both valves 3, 6.

[0073] Opening of the outlet valve 3 allows scavenging gas to clear combustion residues out of the pre-chamber 2 .

[0074] After the piston 9 passes its bottom dead center, the scavenging ports (not shown) are closed.

[0075] Afterwards, if Figure 2d As shown, the outlet valve 3 is closed. At the same time or subsequently, the exhaust valve 6 will also be closed, and the internal combustion engine 100 is in the state of Figure 2a The status shown in .

[0076] Figure 3 The valves 3, 6 during the combustion cycle are shown schematically (see e.g. Figure 1 ) and scavenging ports (see e.g. Figure 1 ) settings.

[0077] When the crankshaft angle is 0°, the piston 6 (see for example Figure 1 ) is at top dead center TDC. Both valves 3 and 6 are closed, which corresponds to Figure 2a The state of the internal combustion engine 100 is shown.

[0078] As the piston moves downward, the volume above the piston increases. During expansion, the pressure decreases.

[0079] At a certain point EVO, when the crankshaft angle increases and the piston 9 moves downward accordingly, the exhaust valve 6 opens, which corresponds to Figure 2b The state of the internal combustion engine 100 is shown.

[0080] At a certain point IPO, when the crank angle is greater than the crank angle at EVO, the scavenging ports are also opened.

[0081] Alternatively, the scavenging ports may be opened before the exhaust valves are opened. However, there is a risk of extensive flashback on the underside of the piston.

[0082] After the scavenging port is opened at point IPO, at point SVO, before or preferably after a crank angle of 180°, the outlet valve 3 is opened, which corresponds to Figure 2c The state of the internal combustion engine 100 is shown.

[0083] After the piston passes the bottom dead center BDC and the crankshaft angle is greater than 180°, at point IPC, the scavenging port is closed.

[0084] The scavenge air ports are closed by a moving piston and / or a corresponding valve.

[0085] When the crankshaft angle is greater than 180°, in particular greater than 270°, at point SVC, the outlet valve 3 is closed. Simultaneously or subsequently, at point EVC, the exhaust valve 6 is also closed. Preferably, the outlet valve 3 is closed after the scavenging port is closed and before or at the same time as the exhaust valve 6 is closed. This corresponds to the following: Figure 2d The state of the internal combustion engine 100 is shown.

[0086] Alternatively, the outlet valve may be closed after the exhaust valve is closed.

[0087] When the piston is close to the top dead center TDC and therefore between the points EVC and EVO, the state of the internal combustion engine corresponds to Figure 2a .

[0088] Figure 4 A schematic diagram of an internal combustion engine 100 is shown.

[0089] The internal combustion engine 100 comprises a first setting unit 14 for setting the outlet valve 3 and a second setting unit 15 for setting the exhaust valve 6 .

[0090] The internal combustion engine 100 comprises a control unit 16 which operates the outlet valve 3 and the exhaust valve 6 in a suitably timed sequence as the piston 9 is displaced.

[0091] The control unit 16 comprises a first output line 17 a which is connected to the first setting unit 14 for setting the outlet valve 3 .

[0092] The control unit 16 comprises a second output line 17 b which is connected to the second setting unit 15 for setting said exhaust valve 6 .

[0093] The control unit 16 includes a third output line 17 c for setting the scavenging port 18 .

[0094] The internal combustion engine 100 comprises a crank angle sensor 22 which is also connected to the control unit 16 .

[0095] The control unit 16 is adapted to control the outlet valve 3 and the exhaust valve 6 in dependence on the crankshaft angle.

[0096] The computer program can be loaded onto the control unit 16 and run on the control unit 16 to achieve Figure 3 The combustion cycle is shown in FIG.

[0097] Figure 5 There is shown a schematic cross-sectional view of a portion of a second example of an internal combustion engine 100. In this example, the pre-combustion chamber 2 comprises a fuel nozzle 20 for injecting pilot fuel.

[0098] Figure 6 There is shown a schematic cross-sectional view of a portion of a third example of an internal combustion engine 100. In this example, the pre-combustion chamber 2 comprises a spark plug 21 which extends into the volume 11 of the pre-combustion chamber.

[0099] Figure 7 A schematic sectional view of a portion of a fourth example of an internal combustion engine 100 is shown, which comprises two exhaust valves 6 .

Claims

1. A pre-combustion chamber for an internal combustion engine (100), wherein the internal combustion engine is a large two-stroke internal combustion engine, and the internal combustion engine comprises: - a cylinder head (4) and a cylinder (10) with a cylinder liner (8); - a piston (9) reciprocatingly received in a cylinder volume (5) formed in said cylinder (10); - at least one exhaust valve (6) arranged in the cylinder head (4) to control the flow of gas from the cylinder volume (5) to an exhaust pipe (7) of the internal combustion engine (100); as well as - the pre-chamber (2), which has a pre-chamber volume (11) fluidically connected to the cylinder volume (5) for igniting the gas / air mixture, Characterized in that the pre-combustion chamber (2) comprises an outlet (1) which can be fluidically connected to the exhaust pipe (7) of the internal combustion engine (100), and the pre-combustion chamber (2) comprises an outlet valve (3) to control the flow of exhaust gas from the pre-combustion chamber (2) to the exhaust pipe (7).

2. An internal combustion engine, the internal combustion engine being a large two-stroke internal combustion engine, comprising: - a cylinder head (4) and a cylinder (10) with a cylinder liner (8); - a piston (9) reciprocatingly received in a cylinder volume (5) formed in said cylinder (10); - at least one pre-combustion chamber (2), said at least one pre-combustion chamber (2) being a pre-combustion chamber according to claim 1; as well as - at least one exhaust valve (6) arranged in the cylinder head (4) to control the flow of gas from the cylinder volume (5) to an exhaust pipe (7) of the internal combustion engine (100).

3. The internal combustion engine according to claim 2, wherein: The outlet valve (3) is slidably received in the pre-combustion chamber (2) and cooperates with an outlet valve seat (12) provided in the wall of the pre-combustion chamber (2).

4. The internal combustion engine according to claim 2, wherein: The internal combustion engine (100) comprises a branch line (13) which is fluidically connected to the exhaust pipe (7) and can be fluidically connected to the outlet (1) of the pre-combustion chamber (2).

5. The internal combustion engine according to claim 2, wherein The cylinder (10) includes an air inlet (18) arranged in the cylinder liner (8).

6. The internal combustion engine according to claim 2, wherein The pre-chamber (2) comprises an ignition device (21) for igniting a gas-air mixture, extending into the pre-chamber volume (11) of the pre-chamber (2), and / or The pre-combustion chamber (2) comprises injection means (20) for injecting a suitable fuel.

7. The internal combustion engine according to claim 2, wherein The internal combustion engine (100) comprises a first setting unit (14) for setting the outlet valve (3).

8. The internal combustion engine according to claim 7, wherein The internal combustion engine (100) comprises a second setting unit (15) for setting the at least one exhaust valve (6).

9. The internal combustion engine according to claim 8, wherein The internal combustion engine comprises a control unit (16) for operating the outlet valve (3) and the at least one exhaust valve (6) in a suitably timed sequence following displacement of the piston (9), The control unit (16) comprises at least one output line (17a, 17b) which is connected or connectable to the first setting unit (14) for setting the outlet valve (3) and / or the second setting unit (15) for setting the at least one exhaust valve (6).

10. The internal combustion engine according to claim 9, wherein The control unit (16) is adapted to control the outlet valve (3) and the at least one exhaust valve (6) such that - during compression, combustion and expansion and when the piston (9) passes its top dead center, the outlet valve (3) and the at least one exhaust valve (6) are closed, - when the piston (9) moves downwards, the at least one exhaust valve (6) opens, - after the exhaust valve opens and / or after air begins to enter the cylinder (10), the outlet valve (3) opens to expel any residue remaining in the pre-combustion chamber (2); After the piston (9) passes its bottom dead center and air stops entering the cylinder (10), the outlet valve (3) is closed and, simultaneously or subsequently, the at least one exhaust valve (6) is closed.

11. A method of operating an internal combustion engine according to claim 2, the method comprising the steps of: - keeping closed said at least one exhaust valve (6) and said outlet valve of said pre-combustion chamber during compression, combustion and expansion and when said piston (9) passes its top dead center, - when the piston (9) moves downward, the exhaust valve (6) is opened, - letting air into the cylinder (10), - opening the outlet valve (3) after the exhaust valve opens and / or after air begins to enter the cylinder (10) in order to expel any residue remaining in the pre-combustion chamber (2); - After the piston (9) passes its bottom dead center and air stops entering the cylinder (10), the outlet valve (3) is closed and, simultaneously or subsequently, the at least one exhaust valve (6) is closed.

12. A computer program for loading into a computer and / or running on a computer, wherein: The computer program is adapted to perform the method according to claim 11 to operate an internal combustion engine according to claim 2.

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