Method for operating an internal combustion engine, and internal combustion engine

Abstract

A method for operating an internal combustion engine 100 wherein in order to abruptly reduce a torque and / or to provide a low torque by the internal combustion engine, an ignition angle adjustment to

Description

The present invention relates to a method for operating an internal combustion engine, wherein, in order to abruptly reduce a torque of the internal combustion engine and / or to provide a low torque by the internal combustion engine, an ignition angle adjustment to later is carried out. The present invention further relates to an internal combustion engine having a control unit configured so as to carry out such a method. An abrupt reduction of a torque of the internal combustion engine allows, for example, for particularly dynamic shifting operations of a transmission coupled to the internal combustion engine or a particularly effective overrun fuel cut-off. In particular, a low torque is understood to mean a torque that cannot be realised solely by adjusting a cylinder charge of the internal combustion engine. For abruptly reducing a torque of an internal combustion engine, it is known from DE 10 2020 116 456 A1 to carry out an ignition angle adjustment to later during a gear shift. The present invention seeks to enable the realization of a dynamically driveable motor vehicle with relatively low fuel consumption. According to a first aspect of the invention there is provided a method for operating an internal combustion engine having the features of claim 1, and according to a second aspect of the invention there is provided an internal combustion engine having the features of claim 3. In the method according to an aspect of the invention for operating an internal combustion engine, in order to enable an abrupt reduction of a torque of the internal combustion engine and / or to provide a particularly low torque by the internal combustion engine, an ignition angle adjustment to later is carried out, wherein the ignition angle is adjusted maximally to later up to a limit ignition angle. The limit ignition angle here indicates a latest possible ignition angle for which misfires can be reliably excluded under the respective operating parameters. Preferably, in order to enable a particularly abrupt reduction in torque, an ignition angle adjustment to the limit ignition angle is carried out. This allows for particularly dynamic shifting operations as well as particularly effective overrun fuel cut-off. In the method according to an aspect of the invention for operating an internal combustion engine, in order to reduce emissions, reduce fuel consumption and / or increase power, water is further injected into an intake tract of the internal combustion engine by means of a water injection system which is configured in a manner known per se. Due to the fact that, by injecting water, the combustion process in the internal combustion engine is “delayed,” in the method according to aspects of the invention for operating an internal combustion engine, in order to avoid misfires, the limit ignition angle for the ignition angle adjustment is determined or adjusted / corrected based on an amount of water injected by the water injection system, wherein the determined limit ignition angle is earlier the greater the amount of water injected by the water injection system. The method according to aspects of the invention thus enables the realization of a dynamically driveable motor vehicle with relatively low fuel consumption. Because the air pressure decreases with increasing geographic elevation, in order to reliably avoid misfires, the limit ignition angle for ignition angle adjustment is preferably additionally determined based on a geographic elevation. The internal combustion engine according to an aspect of the invention comprises a water injection system configured in a manner known per se. The water injection system comprises at least one injection nozzle configured so as to inject water into an intake tract of the internal combustion engine, preferably into a so-called suction tube 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 configured so as to inject water into the suction tube of one of the cylinders. The water injection system typically comprises a pump configured so as to convey water from a water tank via water lines to the at least one injection nozzle. The internal combustion engine according to aspects of the invention further comprises a control unit configured so as to carry out a previously described method according to aspects of the present invention for operating an internal combustion engine. Preferably, the control unit is realised by suitable programming of an engine control unit of the internal combustion engine. By carrying out the method according to aspects of the invention for operating an internal combustion engine, for the aforementioned reasons, the control unit enables the realization of a dynamically driveable motor vehicle with relatively low fuel consumption. An example embodiment of the present invention is described below on the basis of the attached Fig. 1, which shows a schematic diagram of an internal combustion engine according to the invention. Fig. 1 shows an internal combustion engine 100 according to an embodiment of the invention, having a plurality of cylinders 1, an intake tract 2 and an exhaust tract 3, wherein the plurality of cylinders 1 are each connected to the intake tract 2 for supplying combustion air and to the exhaust tract 3 for dissipation of exhaust gas. The internal combustion engine 100 further comprises a water injection system 4 having a number of injection nozzles 4.1 corresponding to the number of cylinders 1, each configured so as to inject water provided via a water line 4.2 into the intake tract 2, specifically into a suction tube 2.1 associated with the cylinder 1. The water injection system 3 further comprises a pump 4.3 and a water tank 4.4, wherein the pump 4.3 is configured so as 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. The internal combustion engine 100 further comprises a control unit 5 configured so as to inject a defined amount of water into the intake tract 2 via the water injection system 3. The control unit 5 is further configured so as to determine a current limit ignition angle based on the amount of water currently injected by the water injection system 3, as well as based on provided information about a current geographic elevation, wherein the limit ignition angle indicates a latest possible ignition angle for which misfires can be safely excluded under the present operating parameters. The control unit 5 is further configured so as to carry out an ignition angle adjustment to later as needed in order to abruptly reduce a torque of the internal combustion engine 100 and / or to provide a particularly low torque by the internal combustion engine 100, wherein the ignition angle adjustment is always limited by the currently determined limit ignition angle. List of reference numerals 100 Internal combustion engine 1 Cylinder 2 Intake tract 2.1 Suction tubes 3 Exhaust tract 4 Water injection system 4.1 Injection nozzles 4.2 Water lines 4.3 Pump 4.4 Water tank 5 Control unit

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