DE102022202952A1 - Method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle and a motor vehicle driven by an internal combustion engine that can be operated using such a method - Google Patents

Abstract

The invention relates to a method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle, with an engine control through which an optimal center of combustion position can be controlled for each operating point of the internal combustion engine, at least in the area of higher load, and through which an actual component temperature of the component and a Actual combustion chamber temperature acting on the component in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, are determined, whereby when the engine control system detects the reaching or exceeding of a critical MAX component temperature of the component in at least one operating point that is critical for the component Internal combustion engine in which the MAX component temperature is reached or exceeded, the ACTUAL combustion chamber temperature in the combustion chamber is reduced.

Description

The invention relates to a method for protecting components of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle and to a motor vehicle driven by an internal combustion engine that can be operated using such a method.

Due to current legislation and the general need for CO ₂ reduction, combustion engines are permanently regulated in the area of the optimal center of combustion. In the areas in which the internal combustion engine is limited by knock, the ignition is regulated at the knock limit in order to maximize the efficiency of the internal combustion engine.

The knock limit refers to the point in time during the operation of an internal combustion engine from which uncontrolled combustion of the fuel occurs in gasoline engines. The temperature and pressure increase sharply, creating more ignition nuclei that overlap at the speed of sound. This causes pressure peaks that can damage pistons, bearings, cylinder heads, valves and spark plugs. The reflection causes a high-frequency oscillation in the cylinder pressure curve, which can be heard. This is called “knocking” in gasoline engines and “nagging” in diesel engines.

Operating the internal combustion engine close to the knock limit leads to early ignition times, which can lead to high thermal stress on components in the internal combustion engine, in particular on injectors, which can lead to engine damage.

One object of an exemplary embodiment of the invention is to propose a method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle and a motor vehicle driven by an internal combustion engine that can be operated using such a method, in which the risk of thermal damage to the component is reduced.

This object is achieved by a method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle, with an engine control through which an optimal center of combustion position can be controlled for each operating point of the internal combustion engine, at least in the area of higher load, and through which an actual component temperature of the component and an ACTUAL combustion chamber temperature acting on the component in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, are determined, wherein when the engine control system detects the reaching or exceeding of a critical MAX component temperature of the component in at least one critical for the component Operating point of the internal combustion engine in which the MAX component temperature is reached or exceeded, the ACTUAL combustion chamber temperature in the combustion chamber is reduced.

By reducing the ACTUAL combustion chamber temperature in the combustion chamber as soon as the engine control system detects that a critical MAX component temperature of the component has been reached or exceeded, the component can be protected from thermal damage.

Operating the internal combustion engine in such a way that an optimal center of combustion position is achieved in the higher load range may include operating the internal combustion engine close to the knock limit.

The knock limit refers to the point in time during the operation of an internal combustion engine from which uncontrolled combustion of the fuel occurs in gasoline engines. The temperature and pressure increase sharply, creating more ignition nuclei that overlap at the speed of sound. This causes pressure peaks that can damage pistons, bearings, cylinder heads, valves and spark plugs. The reflection causes a high-frequency oscillation in the cylinder pressure curve, which can be heard. This is called knocking in gasoline engines and nailing in diesel engines.

An operating point of the internal combustion engine, also called an engine operating point, is to be understood as the outgoing efficiency of an engine's output with regard to the ratio of the drive power of the internal combustion engine and the gear ratio of the transmission. The operating point can be adjusted according to the driving situation or from an economic point of view.

In order to reduce the actual combustion chamber temperature in the combustion chamber, it proves to be advantageous if reducing the actual combustion chamber temperature in the combustion chamber involves reducing the actual pressure in the combustion chamber at the time of ignition of a fuel-air mixture in the combustion chamber and/or increasing it a ratio of fuel to air of the fuel-air mixture in the combustion chamber.

If reducing the ACTUAL combustion chamber temperature in the combustion chamber includes reducing the ACTUAL pressure in the combustion chamber at the time of ignition of a fuel-air mixture in the combustion chamber, the maximum ACTUAL combustion chamber temperature is reduced with respect to an earlier ignition point. This is due to the fact that the actual combustion chamber temperature in the combustion chamber is also reduced due to a reduced actual pressure in the combustion chamber at the time of ignition due to the thermal equation of state in a closed system.

If reducing the ACTUAL combustion chamber temperature in the combustion chamber involves increasing a ratio of fuel to air of the fuel-air mixture in the combustion chamber, this can be cooled by increasing the supplied fuel with the excess fuel acting as a coolant. In this case, lambda, also called air ratio or air number, is increased.

Reducing the actual pressure in the combustion chamber can involve different mechanisms. The actual pressure in the combustion chamber at the time of ignition of the fuel-air mixture can be easily achieved if reducing the actual pressure in the combustion chamber at the time of ignition of the fuel-air mixture in the combustion chamber involves reversing an ignition point by the engine control includes.

As a result, ignition takes place at a time that is delayed from normal ignition, at which the volume in the combustion chamber is expanded anyway due to a piston stroke. Due to the thermal equation of state, as the volume increases, the pressure within the volume of the combustion chamber is also reduced. This means that the actual combustion chamber temperature in the combustion chamber can be reduced without activating or delaying additional components, simply by shifting the ignition point backwards.

In a further development of the last-mentioned embodiment, it proves to be advantageous if the optimal combustion center of gravity position for each operating point of the internal combustion engine comprises a crank angle of 7° to 8° after the top dead center of a crankshaft of the internal combustion engine and/or if the reduced ignition point has a position of 8.1° to 18° degree crank angle coincides after the top dead center of the crankshaft of the internal combustion engine.

If the reversal of the ignition timing includes 8.1° to 18° crank angle after the top dead center of a crankshaft of the internal combustion engine, it can be ensured that sufficient power can still be accessed from the internal combustion engine by the internal combustion engine.

Reducing the ignition timing can basically be solved in any technical way. It proves to be advantageous if the ignition timing is reduced in a single step to a maximum possible reduced ignition timing, in particular that the reduced ignition timing coincides with a position of 18 ° crank angle after the top dead center of the crankshaft of the internal combustion engine or if the ignition timing is withdrawn takes place gradually until the maximum possible retarded ignition point is reached, in particular coinciding with 1° crank angle steps of the crankshaft until reaching 18° crank angle after top dead center of the crankshaft of the internal combustion engine.

If the ignition timing is reduced in a single step, the maximum possible cooling of the component is possible.

If the ignition timing is reduced gradually, in particular coinciding with 1° crank angle steps of the crankshaft, the internal combustion engine can be operated with the maximum possible load, with the component being operated close to the MAX component temperature.

In addition, in embodiments of the method it is provided that the determination of the actual component temperature of the component and the actual combustion chamber temperature acting on the component in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, involves real measurement by at least one sensor means, such as a thermocouple , a calculation using mathematical modeling and / or a comparison of an operating point-dependent map stored in the engine control.

If the determination of the actual component temperature of the component and the actual combustion chamber temperature acting on the component in the combustion chamber involves real measurement by at least one sensor means, a real actual combustion chamber temperature and a real actual component temperature of the component can be detected.

If determining the actual component temperature of the component and the actual combustion chamber temperature acting on the component in the combustion chamber involves calculation using mathematical modeling and/or comparing an operating point-dependent map stored in the engine control system, it is not necessary to install a real sensor means. If the actual component temperature and the actual combustion chamber temperature are calculated using mathematical modeling, there is no need to store the data, which means that the engine control can be designed to be compact. If the determination of the ACTUAL combustion chamber temperature and the ACTUAL component temperature requires a comparison with one stored in the engine control th operating point-dependent map, computing time can be saved and control can be carried out promptly by the engine control.

In a further development of the last-mentioned embodiment, it proves to be advantageous if the operating point-dependent map stored in the engine control includes at least an assignment of a load/speed state of the internal combustion engine to an actual component temperature and/or an actual combustion chamber temperature.

By assigning a load/speed state of the internal combustion engine to an actual component temperature and/or an actual combustion chamber temperature, it can be quickly determined whether the MAX component temperature has been reached. In such a case, exemplary embodiments are conceivable in which the load/speed state is assigned to an actual combustion chamber temperature and from this the actual component temperature is also map-based or can be assigned or determined by means of calculation.

In addition, the load/speed state, in particular as a function of time, can be assigned to both the actual component temperature and the actual combustion chamber temperature.

The operating point-dependent map stored in the engine control can be optimized by recording driving state data on a test bench and storing the recorded driving state data in the engine control to generate the operating point-dependent map stored in the engine control.

The driving status data can be recorded on a test stand and stored in the engine control before the process steps “Determining the actual component temperature and the actual combustion chamber temperature” and “Reducing the actual combustion chamber temperature”.

This can also be done individually for each motor vehicle or on a reference motor vehicle with the same design and the same engine.

In order to always be able to operate the internal combustion engine with the maximum possible load, it proves to be advantageous if the reduced ignition point is brought forward to the optimal combustion center position, in which the ignition point is at a position of 7° to 8° crank angle after the top dead center of the crankshaft Internal combustion engine coincides when the engine control detects that the critical MAX component temperature of the component is undershot in all operating points of the internal combustion engine that are critical for the component.

In this case, the retracted ignition point is brought forward again as soon as the component has cooled down sufficiently, especially if the ACTUAL component temperature is below the critical MAX component temperature. In this case, the internal combustion engine can be operated again with the optimal combustion center position.

In a further development of the last-mentioned embodiment, it proves to be advantageous if the reduced ignition point is brought forward in a single step to the optimal combustion center position, in which the ignition point coincides with a position of 7° to 8° crank angle after the top dead center of the crankshaft of the internal combustion engine, takes place or if the retracted ignition point is advanced gradually until the optimal combustion center position is reached, in particular coinciding with 1° crank angle steps of the crankshaft until reaching 7° to 8° crank angle after top dead center of the crankshaft of the internal combustion engine.

If the retracted ignition timing is advanced in a single step, the internal combustion engine can immediately be operated again with the maximum possible load. If the retarded ignition timing is advanced gradually, the operation of the internal combustion engine can be leveled off at its maximum possible load, at which the component is in the vicinity of its critical MAX component temperature.

The component that is arranged in the combustion chamber can be any component. For example, it can be an inlet valve, an outlet valve, piston or the like. In one embodiment of the method it is provided that the component comprises an injector of the internal combustion engine, which protrudes into the combustion chamber with an injector tip and through which fuel can be fed into the combustion chamber and/or ignited.

Fuel can be fed into the combustion chamber and/or ignited through the injector.

In a further development of the last-mentioned embodiment, it is provided that the actual component temperature determined by the engine control includes an actual injector tip temperature of the injector tip of the injector.

In this case, it can be ensured that the entire component, in particular the injector, is not viewed in terms of its entire actual component temperature, for example capacitively, son but only in a section that is directly exposed to the ACTUAL combustion chamber temperature.

In addition, the method is solved by a motor vehicle powered by an internal combustion engine, which can be operated according to a method with at least one of the aforementioned features, with an internal combustion engine which has at least one cylinder in which a combustion chamber is formed, which has at least one piston which forms the combustion chamber is movably arranged in the cylinder on one side and is connected to a crankshaft, and which comprises at least one component arranged in the combustion chamber, and with at least one engine control assigned to the internal combustion engine, through which an optimal combustion center of gravity position is achieved for each operating point of the internal combustion engine, at least in the area of higher load is controllable and through which an actual component temperature of the component and an actual combustion chamber temperature acting on the component in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, can be determined.

The internal combustion engine can be a direct-injection Otto engine. In addition, it is also conceivable that the internal combustion engine is a diesel engine.

In a further development of the last-mentioned embodiment, it proves to be advantageous if the component comprises an injector which protrudes into the combustion chamber with an injector tip and through which fuel can be fed into the combustion chamber and ignited.

Further features, details and advantages of the invention result from the attached patent claims, from the graphic representation and the following description of a preferred embodiment of the method.

• 1 Ein schematisches Ablaufdiagramm einer Ausführungsform des erfindungsgemäßen Verfahrens;
• 2 Eine graphische Darstellung einer Zurücknahme des Zündzeitpunkts in Bezug des Gradkuppelwinkels der Kurbelwelle in Relation zu einer Reduktion der IST-Brennraumtemperatur im Brennraum.

In the drawing shows:

• 1 A schematic flow diagram of an embodiment of the method according to the invention;
• 2 A graphical representation of a reduction in the ignition timing in relation to the degree dome angle of the crankshaft in relation to a reduction in the ACTUAL combustion chamber temperature in the combustion chamber.

1 shows a method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle. In a step 101, an optimal center of combustion position is controlled by an engine controller for each operating point of an internal combustion engine. In addition, an actual component temperature of a component that is arranged in the combustion chamber of the internal combustion engine and an actual combustion chamber temperature acting on the component in the combustion chamber are determined. Both the actual component temperature of the component and the actual combustion chamber temperature in the combustion chamber are determined depending on the respective operating point of the internal combustion engine. The determination according to step 101 can be carried out using a real sensor means or by calculating using mathematical modeling and/or by comparing an operating point-dependent map stored in the engine control system.

If the engine control detects that the ACTUAL component temperature of the component reaches or exceeds a critical MAX component temperature of the component, the ACTUAL combustion chamber temperature in the combustion chamber is reduced in a step 102. For this purpose, an actual pressure in the combustion chamber is reduced to the ignition point of an ignition of a fuel-air mixture in the combustion chamber. This is done according to the procedure 1 by reversing an ignition point through the engine control.

Reducing the ignition timing by the engine control involves shifting the optimal center of combustion position, which is located at an operating point of the internal combustion engine at 7° to 8° crank angle after the top dead center of a crankshaft of the internal combustion engine, to a position of 8.1° to 18° crank angle the top dead center of the crankshaft.

2 shows a diagram in which the displacement of the degree crank angle beyond the optimal combustion center of gravity position, i.e. beyond 7° to 8° degree crank angle, is plotted on the Degree crank angle from the optimal combustion center position.

Based on 2 It can be seen that by reducing the ignition timing from 8.1° to 18° crank angle after top dead center of the crankshaft, the actual component temperature can be reduced by up to almost 50° K.

Looking in 1 After the ignition point has been withdrawn in step 102, the actual component temperature of the component and the actual combustion chamber temperature acting on the component in the combustion chamber are determined again by the engine control. If the engine control detects that the critical MAX component temperature of the component is in If all operating points of the internal combustion engine that are critical for the component have not been reached, in a step 103 the reduced ignition point is brought forward back towards the optimal combustion center position. This means that the ignition point coincides again at a position of 7° to 8° crank angle after the top dead center of the crankshaft of the internal combustion engine.

In principle, in step 101, the determination of the actual component temperature of the component and the actual combustion chamber temperature in the combustion chamber can be done by the engine control using a real sensor or by calculating using mathematical modeling. If the determination involves comparing an operating point-dependent map stored in the engine control system, the map can be created in an upstream step 100. This can be done, for example, by driving state data on a test bench and storing this data in the engine control to generate an operating point-dependent map stored in the engine control.

The features of the invention disclosed in the above description, in the claims and in the drawing can be essential both individually and in any combination in the implementation of the invention in its various embodiments.

Reference symbol list

100-103

Procedural steps

Claims (14)

Method for component protection of a component arranged in a combustion chamber of an internal combustion engine of a motor vehicle, with an engine control through which an optimal center of combustion position can be controlled for each operating point of the internal combustion engine, at least in the area of higher load, and through which an actual component temperature of the component and one acting on the component ACTUAL combustion chamber temperature in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, are determined, wherein when a critical MAX component temperature of the component is detected by the engine control in at least one operating point of the internal combustion engine that is critical for the component, in which the MAX component temperature is reached or exceeded, the ACTUAL combustion chamber temperature in the combustion chamber is reduced. Procedure according to Claim 1 , characterized in that reducing the ACTUAL combustion chamber temperature in the combustion chamber involves reducing the ACTUAL pressure in the combustion chamber at the time of ignition of a fuel-air mixture in the combustion chamber and / or increasing a ratio of fuel to air of the fuel-air mixture included in the combustion chamber. Procedure according to Claim 2 , characterized in that reducing the actual pressure in the combustion chamber at the time of ignition of the fuel-air mixture in the combustion chamber includes withdrawing an ignition point by the engine control. Method according to one of the preceding claims, characterized in that the optimal center of combustion position for each operating point of the internal combustion engine comprises 7° to 8° crank angle after top dead center of a crankshaft of the internal combustion engine and/or that the retarded ignition point has a position of 8.1° to 18 ° Crank angle after the top dead center of the crankshaft of the internal combustion engine coincides. Procedure according to one of the Claims 3 or 4 , characterized in that the ignition timing is withdrawn in a single step to a maximum possible ignition timing, in particular that the withdrawn ignition timing coincides with a position of 18 ° crank angle after the top dead center of the crankshaft of the internal combustion engine or that the ignition timing is withdrawn gradually up to Reaching the maximum possible retarded ignition point occurs, in particular coinciding with 1° crank angle steps of the crankshaft until reaching 18° crank angle after top dead center of the crankshaft of the internal combustion engine. Method according to one of the preceding claims, characterized in that the determination of the actual component temperature of the component and the actual combustion chamber temperature acting on the component in the combustion chamber, both in particular depending on the respective operating point of the internal combustion engine, involves real measurement by at least one sensor means, such as Thermocouple, a calculation using mathematical modeling and / or a comparison of an operating point-dependent map stored in the engine control. Procedure according to Claim 6 , characterized in that the operating point-dependent map stored in the engine control at least assigns a load/speed state of the internal combustion engine to an actual component temperature ture and/or an actual combustion chamber temperature. Procedure according to Claim 6 or 7 , characterized by recording driving state data on a test bench and storing the recorded driving state data in the engine control to generate the operating point-dependent map stored in the engine control. Method according to one of the preceding claims, characterized in that the withdrawn ignition point is brought forward to the optimal combustion center of gravity position, in which the ignition point coincides with a position of 7° to 8° crank angle after the top dead center of the crankshaft of the internal combustion engine when activated by the engine control Falling below the critical MAX component temperature of the component is recorded in all operating points of the internal combustion engine that are critical for the component. Procedure according to Claim 9 , characterized in that the retracted ignition point is brought forward in a single step to the optimal combustion center position, in which the ignition point coincides with a position of 7° to 8° crank angle after the top dead center of the crankshaft of the internal combustion engine, or that the retracted point is advanced Ignition timing occurs gradually until the optimal center of combustion position is reached, in particular coinciding with 1° crank angle steps of the crankshaft until reaching 7° to 8° crank angle after top dead center of the crankshaft of the internal combustion engine. Method according to one of the preceding claims, characterized in that the component comprises an injector of the internal combustion engine, which protrudes into the combustion chamber with an injector tip and through which fuel can be fed into the combustion chamber and/or ignited. Procedure according to Claim 11 , characterized in that the actual component temperature determined by the engine control includes an actual injector tip temperature of the injector tip of the injector. Motor vehicle powered by an internal combustion engine, which uses a method according to one of the Claims 1 until 12 is operable, with an internal combustion engine which has at least one cylinder in which a combustion chamber is formed, the at least one piston which is movably arranged in the cylinder to limit the combustion chamber on one side and is connected to a crankshaft, and the at least one arranged in the combustion chamber Component includes, and with at least one engine control assigned to the internal combustion engine, through which an optimal combustion center position can be controlled for each operating point of the internal combustion engine, at least in the area of higher load, and through which an actual component temperature of the component and an actual combustion chamber temperature acting on the component in the combustion chamber, Both can be determined in particular depending on the respective operating point of the internal combustion engine. motor vehicle Claim 13 , characterized in that the component comprises an injector which protrudes into the combustion chamber with an injector tip and through which fuel can be fed into the combustion chamber and ignited.

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