Method for operating an internal combustion engine and internal combustion engine

Abstract

The present invention relates to a method for operating an internal combustion engine (100), wherein, in order to abruptly reduce a torque of the internal combustion engine (100) and / or to provide a low torque by the internal combustion engine (100), a retarded ignition angle adjustment is carried out, wherein water is injected into an intake tract (2) of the internal combustion engine (100) by means of a water injection system (4), and wherein a limit ignition angle for the ignition angle adjustment is determined based on a quantity of water injected by the water injection system (4). The present invention further relates to an internal combustion engine (100) comprising a water injection system (4) and a control unit (5) that is configured to carry out an inventive method for operating the internal combustion engine (100).

Description

[0001] The present invention relates to a method for operating an internal combustion engine, wherein, in order to abruptly reduce the torque of the internal combustion engine and / or to provide low torque by the internal combustion engine, an ignition timing adjustment is retarded. The present invention further relates to an internal combustion engine with a control unit configured to carry out such a method.

[0002] For example, an abrupt reduction in the torque of the combustion engine enables particularly dynamic shifting operations of a transmission coupled to the combustion engine or a particularly effective overrun cut-off.

[0003] Low torque refers in particular to torque that cannot be achieved solely by adjusting the cylinder filling of the internal combustion engine.

[0004] From DE 10 2020 116 456 A1 it is known to retard the ignition timing in order to abruptly reduce the torque of an internal combustion engine during a gear change.

[0005] From DE 10 2016 214 641 A1 it is known to carry out water injection with an increased amount of water as a reaction to super knocking and / or glow ignition.

[0006] The present invention is based on the objective of enabling the realization of a dynamically drivable motor vehicle with relatively low fuel consumption.

[0007] This problem is solved according to the invention by a method for operating an internal combustion engine with the features of claim 1 and by an internal combustion engine with the features of claim 3.

[0008] In the inventive method for operating an internal combustion engine, an ignition timing adjustment is performed to enable an abrupt reduction in engine torque and / or to provide a particularly low torque. The ignition timing is retarded up to a maximum limit ignition timing. This limit ignition timing represents the latest possible ignition timing for which misfires can be reliably prevented under the prevailing operating parameters. Preferably, the ignition timing is adjusted to the limit ignition timing to enable a particularly abrupt reduction in torque. This allows for particularly dynamic gear changes and especially effective overrun fuel cut-off.

[0009] In the inventive method for operating an internal combustion engine, water is injected into an intake tract of the internal combustion engine by means of a water injection system designed in a generally known manner in order to reduce emissions, reduce fuel consumption and / or increase performance.

[0010] Since the combustion process in the internal combustion engine is "delayed" by the injection of water, in the inventive method for operating an internal combustion engine to avoid misfires, the limit ignition angle for the ignition angle adjustment is determined or adjusted / corrected based on a quantity of water injected by the water injection system, wherein the determined limit ignition angle is earlier the larger the quantity of water injected by the water injection system.

[0011] The method according to the invention thus enables the realization of a dynamically drivable motor vehicle with relatively low fuel consumption.

[0012] Since air pressure decreases with increasing geographical altitude, the limit ignition angle for the ignition angle adjustment is preferably also determined based on a geographical altitude to reliably avoid misfires.

[0013] The internal combustion engine according to the invention comprises a water injection system designed in a generally known manner. The water injection system comprises at least one injection nozzle configured to inject water into an intake tract of the internal combustion engine, preferably into a so-called intake manifold of the internal combustion engine. Preferably, the water injection system comprises a number of injection nozzles corresponding to the number of cylinders of the internal combustion engine, each of which is configured to inject water into the intake manifold of one of the cylinders. The water injection system typically includes a pump configured to deliver water from a water tank via water lines to the at least one injection nozzle.

[0014] The internal combustion engine according to the invention further comprises a control unit configured to execute a previously described method according to the invention for operating an internal combustion engine. Preferably, the control unit is implemented by suitable programming of an engine control unit of the internal combustion engine.

[0015] For the reasons mentioned above, the control unit enables the realization of a dynamically drivable motor vehicle with relatively low fuel consumption by carrying out the inventive method for operating an internal combustion engine.

[0016] An embodiment of the present invention is described below with reference to the attached Fig. 1 described, which shows a schematic diagram of an internal combustion engine according to the invention.

[0017] Fig.Figure 1 shows an internal combustion engine 100 according to the invention with several cylinders 1, an intake tract 2 and an exhaust tract 3, wherein the several cylinders 1 are each connected to the intake tract 2 for the supply of combustion air and to the exhaust tract 3 for the discharge of exhaust gas.

[0018] The internal combustion engine 100 further comprises a water injection system 4 with a number of injection nozzles 4.1 corresponding to the number of cylinders 1, each of which is configured to inject water supplied via a water line 4.2 into the intake tract 2, specifically into an intake manifold 2.1 assigned to one of the cylinders 1.

[0019] The water injection system 3 further comprises a pump 4.3 and a water tank 4.4, wherein the pump 4.3 is configured to supply water from the water tank 4.4 to the injection nozzles 4.1 via the water lines 4.2 at a defined water pressure.

[0020] The internal combustion engine 100 further comprises a control unit 5 which is designed to inject a defined quantity of water into the intake tract 2 by means of the water injection system 3.

[0021] The control unit 5 is further configured to determine a current limit ignition angle based on the amount of water currently injected by the water injection system 3 and based on information provided about a current geographical altitude, whereby the limit ignition angle indicates a latest possible ignition angle for which misfires can be reliably excluded under the respective operating parameters.

[0022] The control unit 5 is further equipped to retard the ignition timing as required to abruptly reduce the torque of the internal combustion engine 100 and / or to provide a particularly low torque by the internal combustion engine 100, whereby the ignition timing adjustment is always limited by the currently determined limit ignition angle. Reference symbol list 100 internal combustion engine 1 cylinder 2 Intake tract 2.1 Intake manifolds 3 Exhaust system 4 Water injection system 4.1 Fuel injectors 4.2 Water pipes 4.3 Pump 4.4 Water tank 5 Control unit

Claims

[1] Method for operating an internal combustion engine (100) wherein an ignition timing adjustment to be carried out in order to abruptly reduce a torque of the internal combustion engine (100) and / or to provide a low torque by the internal combustion engine (100), characterized by , that Water is injected into an intake manifold (2) of the internal combustion engine (100) by means of a water injection system (4), and a limit ignition angle for the ignition angle adjustment is determined based on a quantity of water injected by the water injection system (4). [2] Method according to claim 1, wherein the limit ignition angle for the ignition angle adjustment is additionally determined based on a geographical altitude. [3] Internal combustion engine (100) comprising a water injection system (4) and a control unit (5) configured to perform a method according to one of the preceding claims.

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