Combustion engine with pre-chamber

Abstract

To provide an internal combustion engine 100 with a pre-chamber 2, a method of operating the internal combustion engine 100 with the pre-chamber 2, and the pre-chamber 2.SOLUTION: An combustion engine, preferably a large two-stroke internal combustion engine comprises a cylinder 10 with a cylinder liner 8 and a cylinder head 4, at least one piston 9 reciprocatably received in a cylinder volume 5 formed in the cylinder 10. The combustion engine further comprises at least one pre-chamber 2, preferably arranged in the cylinder head 4, with a pre-chamber volume 11 being fluidly connected to the cylinder volume 5 for ignition of a gas / air mixture, and at least one exhaust valve 6 arranged in the cylinder head 4 to control gas flow from the cylinder volume 5 to an exhaust pipe 7 of the combustion engine 100. The pre-chamber 2 comprises an outlet 1 which is fluidly connectable to the exhaust pipe 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine with a prechamber, a method of operating an internal combustion engine with a prechamber, a prechamber, and a computer program. [Background technology]

[0002] Lean-running engines with large cylinder bore typically feature a pre-chamber assembly to ensure the engine's ignition process. The pre-chamber has a pre-chamber volume that is in fluid communication with the cylinder's main combustion chamber through one or more small openings.

[0003] The present invention preferably relates to an internal combustion engine, such as a marine or ship engine, or a stationary engine, the cylinder of which has a bore of at least 200 mm. 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 multi-fuel engine. The engine speed is preferably less than 800 RPM (four-stroke), more preferably less than 200 RPM (two-stroke), which indicates that it is designated as a low-speed engine.

[0004] Prechambers are particularly used in so-called lean-burn engines, where a powerful ignition source is required. In this case, the prechamber is used to provide a large amount of energy to ignite the lean gas mixture in the main combustion chamber. In the prechamber, the lean basic air-gas mixture coming from the main combustion chamber can be ignited by injecting a suitable fuel that is reactive in excess air and autoigniting it above certain pressure and temperature conditions, or by using a glow or spark plug in combination with a local stoichiometric air-gas mixture, which may be obtained by adding an appropriate amount of gas directly to the prechamber.

[0005] The prechamber geometry differs depending on the actual ignition method. Ignition of the pilot fuel, with or without a glow plug, can provide greater ignition energy than conventional spark-type prechamber ignition systems.

[0006] The requirement is generally fast and repeatable mixing of the basic air-gas fuel mixture taken into the prechamber and ultimately of the pilot fuel to be injected.

[0007] The pre-chamber must be primed for each new cycle: residue left in the pre-chamber from the previous cycle can cause an increase in temperature and can also promote excessive auto-ignition.

[0008] Although several pre-chamber arrangements are known, they are unable to simultaneously meet the above requirements. Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to avoid the drawbacks of the prior art and to provide a combustion engine, a method of using a combustion engine and a pre-chamber, which allows the pre-chamber to function optimally in relation to the combustion cycle. [Means for solving the problem]

[0010] This object is achieved by a combustion engine, a method for operating a combustion machine, a pre-chamber according to the independent claims, and a computer program according to the independent claims.

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

[0012] The combustion engine includes at least one cylinder having a cylinder liner and a cylinder head, and at least one piston reciprocally received within a cylinder volume defined within the cylinder.

[0013] The pistons are typically connected to a crankshaft and are arranged to reciprocate between top dead center (TDC) and bottom dead center (BDC) during engine operation.

[0014] At least one exhaust valve is disposed in the cylinder head and controls gas flow from the cylinder volume to the exhaust pipe of the combustion engine.

[0015] Combustion engines include at least one pre-chamber in which the gas / air mixture is ignited.

[0016] The ratio of the prechamber volume to the compression volume of the combustion cylinder may be between 0.1 and 1%, preferably between 0.1 and 0.8%, and most preferably between 0.1 and 0.5%.

[0017] At least one prechamber having a prechamber volume is fluidly connected to the cylinder volume. The prechamber may be located in the cylinder head.

[0018] The prechamber has at least one outlet fluidly connectable to the exhaust pipe, and the prechamber includes at least one outlet valve for controlling exhaust flow from the prechamber to the exhaust pipe. If the prechamber has multiple outlets, each outlet can be controlled by a valve. The outlet valve can be slidably received in the prechamber and can cooperate with an outlet valve seat located in the wall of the prechamber.

[0019] The pre-chamber outlet, specifically the valve seat of the outlet valve, may be located away from the opening or duct that allows fluid connection to the cylinder volume. The outlet may be located on the opposite side of the opening or duct.

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

[0021] The pre-chamber may be fluidly connectable to the exhaust pipe by one or more supply pipes, which may allow the pre-chamber to be located remotely from the exhaust valve.

[0022] The exhaust valve may be located in the center of the cylinder head. The pre-chamber may be located in the cylinder head at a distance to the cylinder liner that is shorter than the distance to the radial center of the cylinder. Thus, the pre-chamber may be located eccentrically with respect to the main axis of the combustion cylinder.

[0023] Alternatively, the exhaust valve may be positioned eccentrically relative to the major axis of the combustion cylinder. Preferably, the combustion engine comprises exactly one pre-chamber having one or more outlets.

[0024] The pre-chamber may be disposed around the exhaust pipe. The pre-chamber may be disposed annularly with respect to the exhaust valve.

[0025] The combustion engine may be provided with multiple pre-chambers, preferably all pre-chambers being provided with an outlet and an outlet valve.

[0026] The cylinder preferably has an air inlet disposed in the cylinder liner. Specifically, the cylinder has a scavenging port disposed in the cylinder liner. The internal combustion engine may be a longitudinally flushed two-stroke engine.

[0027] The pre-chamber may be provided with ignition means, preferably a spark plug, for igniting the gas-air mixture, the ignition means extending into an ignition chamber of the pre-chamber.

[0028] The pre-chamber may be provided with injection means, in particular a fuel nozzle, for injecting a suitable pilot fuel, by which 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.

[0029] The combustion engine may comprise a first setting unit for setting the outlet valve. The first setting unit makes it possible to actuate the outlet valve. The outlet valve may be actuated by compressed air, hydraulically or electrically. The first setting unit may also be configured to set multiple outlet valves, for example multiple outlet valves of one pre-chamber and / or multiple outlet valves of different pre-chambers.

[0030] Preferably, the combustion engine is provided with a second setting unit for setting at least one exhaust valve. The second setting unit allows the exhaust valve to be actuated. The exhaust valve can be actuated by compressed air, hydraulically or electrically. If the on cylinder is provided with multiple exhaust valves, there can be an on second setting unit for all exhaust valves or multiple second setting units, for example, one second setting unit for each of the exhaust valves.

[0031] Thus, the outlet valve and the exhaust valve can be operated independently of each other.

[0032] Alternatively, the actuation of the exhaust and outlet valves may be coupled such that movement of one valve may cause movement of the other valve.

[0033] The setting unit may comprise a switch and / or a valve.

[0034] In an advantageous embodiment of the combustion engine, the combustion engine comprises a control unit which operates said outlet valve and said exhaust valve in an appropriately timed sequence depending on the displacement of said piston.

[0035] The control unit preferably comprises at least one output line connected or connectable to a first setting unit for setting the outlet valve and / or a second setting unit for setting the exhaust valve.

[0036] Preferably, the control unit comprises at least one first output line and at least one second output line, the first output line being connected or connectable to a first setting unit for setting the exhaust valve, and the second output line being connected or connectable to a second setting unit for setting the exhaust valve.

[0037] The control unit is specifically configured to control the outlet valve and preferably the at least one exhaust valve, and is capable of sending corresponding signals to each setting unit via respective output lines.

[0038] A control unit may be configured to control the outlet valve and the at least one exhaust valve so that both valves are closed during compression, combustion, and expansion and while the piston passes top dead center. The control unit may enable the exhaust valve to open after the piston passes top dead center and during the piston's downward movement.

[0039] The control unit may enable the outlet valve to open, preferably after the exhaust valve has been opened and / or after air has started to enter the cylinder, in order to expel any residue remaining in the pre-chamber.

[0040] The control unit may enable the outlet valve to close after the piston has passed bottom dead center and air has stopped entering the cylinder, preferably at the same time or thereafter the control unit may enable the exhaust valve to close.

[0041] Preferably, the control unit is also configured to control the inlet of air into the cylinder. The combustion engine may comprise a setting unit for setting the air inlet valve, and the control unit may comprise a further output line connected or connectable to the setting unit for setting the air inlet valve.

[0042] The objects of the present invention are also achieved by a method of operating an internal combustion engine as described above. The method includes the following steps.

[0043] The at least one exhaust valve and the at least one outlet valve of the pre-chamber are maintained closed during compression, combustion, and expansion and while the piston passes through top dead center of the piston.

[0044] While the piston is moving downward, the exhaust valve is opened to allow the exhaust gases to flow out of the cylinder. After the exhaust valve is opened, air can enter the cylinder. The exhaust is forced out of the cylinder.

[0045] To expel any residue remaining in the pre-chamber, the outlet valve is preferably opened after the exhaust valve is opened and / or after air begins to enter the cylinder. After the piston passes bottom dead center, air stops entering the cylinder. The outlet valve is closed, and preferably simultaneously or subsequently, the exhaust valve is closed.

[0046] The objects of the present invention are also achieved by a prechamber for a combustion engine as described above, the prechamber having an outlet fluidly connectable to an exhaust pipe of the combustion engine, the prechamber including an outlet valve for controlling exhaust flow from the prechamber to the exhaust pipe.

[0047] The objects of the present invention are also achieved by a computer program, loaded into and / or run on a computer, configured to perform a method for operating the internal combustion engine as described above, in particular for operating the output valves and the exhaust valves in a suitably timed sequence depending on the displacement of the piston.

[0048] The computer program may be loaded into and / or executed on a control unit of the combustion engine, as described above.

[0049] The computer program may be loaded onto and / or executed on a central computer device on the ship.

[0050] In the following, the invention is further explained in examples and with the aid of figures. [Brief explanation of the drawings]

[0051] [Figure 1] 1 is a schematic cross-sectional view of a portion of a first example of a combustion engine; [Figure 2a] 1 is a cross-sectional view of a portion of a combustion engine, showing diagrammatically the various positions of a valve during a combustion cycle; [Figure 2b] 1 is a cross-sectional view of a portion of a combustion engine, showing diagrammatically the various positions of a valve during a combustion cycle; [Figure 2c] 1 is a cross-sectional view of a portion of a combustion engine, showing diagrammatically the various positions of a valve during a combustion cycle; [Figure 2d] 1 is a cross-sectional view of a portion of a combustion engine, showing diagrammatically the various positions of a valve during a combustion cycle; [Figure 3] FIG. 10 is a diagram illustrating, in a simplified manner, the valve settings during the combustion cycle. [Figure 4] 1 is a schematic diagram of a combustion engine. [Figure 5] FIG. 2 is a schematic cross-sectional view of a portion of a second example of a combustion engine. [Figure 6] FIG. 10 is a schematic cross-sectional view of a portion of a third example of a combustion engine. [Figure 7] FIG. 10 is a schematic cross-sectional view of a part of a fourth example of a combustion engine. DETAILED DESCRIPTION OF THE INVENTION

[0052] FIG. 1 shows a schematic cross-sectional view of a portion of a first example of a combustion engine 100 .

[0053] The internal combustion engine 100 includes a cylinder with a cylinder liner 8 and a cylinder head 4. A piston 9 moves up and down within a cylinder volume 5 defined within the cylinder 10. Scavenging ports 18 are disposed in the cylinder liner 8. As shown in the figure, air can enter the cylinder 10 when the piston 9 is at bottom dead center.

[0054] Fuel inlets, not shown, may also be located in the cylinder liner.

[0055] An exhaust valve 6 is arranged in the cylinder head 4 and controls the gas flow from the cylinder volume 5 to an exhaust pipe 7 of the combustion engine 100 .

[0056] The exhaust pipe 7 can guide the exhaust gases to an exhaust gas manifold and / or to the turbine of a turbocharger, not shown in the figure.

[0057] The combustion engine 100 further comprises a pre-chamber 2 arranged in the cylinder head 4. A pre-chamber duct 19 fluidly connects the volume 11 of the pre-chamber 2 with the cylinder volume 5.

[0058] The pre-chamber 2 has an outlet 1 fluidly connectable to an exhaust pipe 7. An outlet valve 3 is disposed at the outlet 1. The outlet valve 3 is slidably received in the pre-chamber 2 and cooperates with an outlet valve seat 12 disposed in a wall of the pre-chamber 2.

[0059] The outlet valve 3 controls fluid communication between the prechamber volume 11 and a supply pipe 13 that directs any fluid from the prechamber volume 11 to the exhaust pipe 7 .

[0060] Figures 2a to 2d show, in cross section through a portion of a combustion engine 100, the various positions of the valves 6, 3 during the combustion cycle.

[0061] As shown in Figure 2a, when the piston 9 passes the top dead center of the piston 9, the exhaust valve 6 and the outlet valve 3 are closed.

[0062] As the piston 9 moves further downward, as shown in Figure 2b, the exhaust valve 6 opens and residue begins to be expelled from the cylinder volume 5. The scavenging ports, not shown in this diagram, open and fresh air begins to enter the cylinder volume 5.

[0063] The outlet valve 3 then also opens, as shown in Figure 2c. The exhaust gases are discharged through both valves 3, 6.

[0064] Opening the outlet valve 3 allows scavenging air to remove combustion residues from the pre-chamber 2 .

[0065] After the piston 9 passes the bottom dead center, the scavenging ports (not shown) are closed.

[0066] Thereafter, as shown in Figure 2d, the outlet valve 3 is closed. At the same time or later, the exhaust valve 6 is also closed and the combustion engine 100 is again in the state shown in Figure 2a.

[0067] FIG. 3 shows diagrammatically the settings of the valves 3, 6 (see, for example, FIG. 1) and the scavenge ports (see, for example, FIG. 1) during the combustion cycle.

[0068] At a crank angle of 0°, the piston 6 (see, for example, FIG. 1) is at top dead center TDC. As shown in FIG. 2a, in accordance with the state of the combustion engine 100, the vote valves 3, 6 are closed.

[0069] The piston moves downward and the volume above the piston increases. During expansion, the pressure decreases.

[0070] At a given point EVO, the crank angle increases and the pistons 9 move downwards respectively, causing the exhaust valves 6 to open, corresponding to the state of the combustion engine 100, as shown in FIG. 2b.

[0071] At a given point IPO, when the crank angle is greater than the crank angle at EVO, the scavenging ports are also opened.

[0072] Alternatively, the scavenging ports can be opened before the exhaust valve, but this risks creating a large amount of blowback on the underside of the piston.

[0073] After the scavenging ports open at point IPO, at point SVO, the outlet valve 3 opens before or preferably after a crank angle of 180°, depending on the state of the combustion engine 100, as shown in FIG. 2c.

[0074] After the piston passes bottom dead center (BDC) and the crank angle reaches a larger value of 180°, the scavenging ports are closed at point IPC.

[0075] The scavenging ports are closed by a moving piston and / or by respective valves.

[0076] When the crank angle is greater than 180°, particularly greater than 270°, the outlet valve 3 is closed at point SVC. At the same time or later, the exhaust valve 6 is also closed at point EVC. The outlet valve 3 is preferably closed after the scavenging ports are closed and before or at the same time as the exhaust valve 6 is closed. The outlet valve 3 corresponds to the state of the combustion engine 100 as shown in Fig. 2d. Alternatively, the outlet valve may be closed after the exhaust valve is closed.

[0077] As the piston approaches top dead center TDC, and thus between points EVC and EVO, the state of the combustion engine corresponds to Figure 2a.

[0078] FIG. 4 shows a schematic diagram of a combustion engine 100 .

[0079] 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 .

[0080] The internal combustion engine 100 comprises a control unit 16 which operates the outlet valve 3 and the exhaust valve 6 in a properly timed sequence depending on the displacement of the piston 9 .

[0081] The control unit 16 comprises a first output line 17 a connected to a first setting unit 14 for setting the outlet valve 3 .

[0082] The control unit 16 has a second output line 17 b connected to a second setting unit 15 which sets the exhaust valve 6 .

[0083] The control unit 16 has a third output line 17c for setting the scavenging port 18.

[0084] The combustion engine 100 is equipped with a crank angle sensor 22 , which is also connected to the control unit 16 .

[0085] The control unit 16 is configured to control the outlet valve 3 and the exhaust valve 6 depending on the crank angle.

[0086] A computer program may be loaded into and executed on the control unit 16 to operate the combustion cycle shown in FIG.

[0087] Figure 5 shows a schematic cross-sectional view of a portion of a second example of a combustion engine 100. In this example, the pre-chamber 2 is equipped with a fuel nozzle 20 for injecting pilot fuel.

[0088] 6 shows a schematic cross-sectional view of a part of a third example of a combustion engine 100. In this example, the pre-chamber 2 is equipped with a spark plug 21 that extends into the volume 11 of the pre-chamber.

[0089] FIG. 7 shows a schematic cross-sectional view of a part of a fourth example of a combustion engine 100 with two exhaust valves 6 .

Claims

1. A combustion engine, namely a large longitudinal flush two-stroke internal combustion engine, a cylinder (10) comprising a cylinder liner (8) and a cylinder head (4); at least one piston (9) reciprocally received within a cylinder volume (5) defined within said cylinder (10); at least one prechamber (2) having a prechamber volume (11) fluidly connected to said cylinder volume (5) for igniting a gas / air mixture; at least one exhaust valve (6) arranged in the cylinder head (4) for controlling the gas flow from the cylinder volume (5) to an exhaust pipe (7) of the combustion engine (100); Equipped with The cylinder (10) is provided with an air inlet (18) arranged in the cylinder liner (8); 1. A combustion engine, characterized in that the pre-chamber (2) has an outlet (1) fluidly connectable to the exhaust pipe (7), the pre-chamber (2) comprising an outlet valve (3) for controlling the exhaust flow from the pre-chamber (2) to the exhaust pipe (7).

2. 2. A combustion engine according to claim 1, wherein the outlet valve (3) is slidably received in the pre-chamber (2) and cooperates with an outlet valve seat (12) arranged in a wall of the pre-chamber (2).

3. 3. The combustion engine (100) according to claim 1 or 2, wherein the combustion engine (100) comprises a supply pipe (13) fluidly connected to the exhaust pipe (7) and fluidly connectable to the outlet (1) of the pre-chamber (2).

4. 2. A combustion engine according to claim 1, wherein the air inlet (18) is formed by a scavenging port.

5. 2. A combustion engine according to claim 1, wherein the pre-chamber (2) comprises at least one of ignition means (21) for igniting a gas-air mixture and injection means (20) for injecting a suitable fuel, extending into the volume (11) of the pre-chamber (2).

6. 2. A combustion engine according to claim 1, wherein the combustion engine (100) comprises a first setting unit (14) for setting the outlet valve (3).

7. the combustion engine comprises a control unit (16) for operating the outlet valve (3) and the exhaust valve (6) in a timed sequence according to the displacement of the piston (9); 2. A combustion engine according to claim 1, wherein the control unit (16) comprises at least one output line (17a, 17b) connected or connectable to at least one of a first setting unit (14) for setting the outlet valve (3) and a second setting unit (15) for setting the exhaust valve (6).

8. The control unit (16) is configured to control the outlet valve (3) and the at least one exhaust valve (6), thereby During compression, combustion and expansion, and while the piston (9) passes through top dead center of the piston (9), both valves (3, 6) are closed; During the downward movement of the piston (9), the exhaust valve (6) is opened, the outlet valve (3) is opened after the exhaust valve is opened and / or air begins to enter the cylinder (10) in order to expel any residue remaining in the pre-chamber (2); 8. A combustion engine according to claim 7, wherein the outlet valve (3) is closed after the piston (9) has passed its bottom dead centre and air has stopped entering the cylinder (10), and simultaneously or thereafter the exhaust valve (6) is closed.

9. 9. A method of operating an internal combustion engine according to any one of claims 1 to 8, comprising: maintaining said at least one exhaust valve (6) and said pre-chamber outlet valve (3) closed during compression, combustion and expansion and while said piston (9) passes through top dead center of said piston (9); opening the exhaust valve (6) while the piston (9) is moving downwards; Allowing air to enter said cylinder (10); opening the outlet valve (3) after the exhaust valve has been opened and / or air has started to enter the cylinder (10) in order to expel any residue remaining in the pre-chamber (2); air stops entering the cylinder (10) after the piston (9) passes the bottom dead center of the piston (9); closing the outlet valve (3) and simultaneously or subsequently closing the exhaust valve (6); A method comprising:

10. 10. A computer program when loaded onto and / or run on a computer, the computer program being configured to perform a method according to claim 9 for operating an internal combustion engine according to any one of claims 1 to 8.

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