Method and control device for operating an internal combustion engine

Abstract

A method for operating an internal combustion engine fried with a heavy fuel oil or an HFO fuel, wherein operating parameters for the internal combustion engine are Applied in particular when for the parameter application the internal combustion engine is operated with a marine gas oil fuel or a DMA fuel, wherein in particular when the internal combustion engine is fired with an HFO fuel, at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, adjusted with an offset.

Description

[0001] The invention relates to a method for operating an internal combustion engine fired with heavy fuel oil according to the preamble of claim 1. The invention, furthermore, relates to a control device for operating an internal combustion engine fired with heavy fuel oil.

[0002] From practice it is known that internal combustion engines, which in field operation are fired with a heavy fuel oil (HFO), are open-loop or closed-loop controlled based on operating parameters, which are applied in particular when the internal combustion engine for application purposes is operated in the application mode with a marine gas oil fuel or a DMA fuel, which is also called MGO (marine gas oil) fuel. In particular when an internal combustion engine, the operating parameters of which were determined subject to the internal combustion engine being fired with a DMA fuel, is fired in field mode with an HFO fuel, deviations in the operating behavior applied for the DMA fuel materialise. Accordingly, Fig. 1 in each case shows a cylinder pressure pz over the crankshaft angle cp and on the other hand a heat quantity Qb given off by the fuel namely on the one hand with the curve profiles 10, 11 a reference curve profile using a DMA fuel and on the other hand with the curve profiles 12, 13 actual curve profiles which materialize when in field mode the internal combustion engine is operated with an HFO fuel, however using the operating parameters determined in the application mode using a DMA fuel. From the curve profiles of Fig. 1 it is evident that clear deviations between the reference curve profile 10 and the respective actual curve profile and thus a clear deviation between a reference operating behavior and an actual operating behavior on the internal combustion engine are then formed.

[0003] Such a deviation in the operating behavior is undesirable. There is therefore a need for a method and a control device for operating an internal combustion engine, with the help of which such deviations can be reduced. Starting out from this, the present invention is based on the object of creating a new type of method for operating an internal combustion engine fired with heavy fuel oil and a control device for carrying out the method.

[0004] This object is solved through a method according to claim 1. According to the invention, at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, adjusted with an offset in particular when the internal combustion engine is fired with an HFO fuel. By adjusting the operating parameters, which were determined subject to firing the internal combustion engine with a DMA fuel, using an offset, it is possible in particular when the internal combustion engine in field mode is fired with an HFO fuel, to approximate the actual operating behavior of the internal combustion engine to a reference operating behavior thus reducing deviations between the reference operating behavior and the actual operating behavior.

[0005] According to an advantageous further development, a start of energisation for fuel injectors of a common rail fuel supply system and / or a storage pressure for fuel storage units of a common rail fuel supply system adjusted with an offset as operating parameter. The adjusting of these operating parameters with an offset is particularly preferred for approximating the actual operating behavior to the reference operating behavior.

[0006] According to an advantageous further development, the respective offset for the respective operating parameter is determined dependent on the current load of the internal combustion engine and / or dependent on the current rotational speed of the internal combustion engine and / or depending on the current fuel quality . By means of this, the respective offset can be particularly advantageously determined.

[0007] Preferentially, dependent on the current load and / or the current rotational speed of the internal combustion engine a current maximum offset is determined, wherein dependent on the current fuel quality a current offset is determined from the current maximum offset, with which the respective operating parameter , which was determined subject to firing the internal combustion engine with a DMA fuel, is adjusted. This determination of the offset for the respective operating parameter is simple. Furthermore, the actual operating behavior can be particularly advantageously approximated to the reference operating behavior using such an offset. The control device according to the invention is defined in claim 7.

[0008] Preferred further developments of the invention are obtained from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail by way of the drawing without being restricted to this. There it shows: Fig. 1: diagrams for illustrating the procedure known from the prior art for operating an internal combustion engine fired with heavy fuel oil; and Fig. 2: diagrams for illustrating the method according to the invention for operating an internal combustion engine fired with heavy fuel oil.

[0009] The present invention relates to a method for operating an internal combustion engine, which in field operation or field mode is typically fired with a heavy fuel oil fuel. Furthermore, the invention relates to a control device for carrying out the method.

[0010] The operation of the internal combustion engine is open-loop or closed-loop controlled based on operating parameters stored in a control device of the internal combustion engine, wherein the operating parameters for the internal combustion engine stored in the control device are applied in particular when in an application mode for parameter application the internal combustion engine is operated with a marine gas oil fuel or a DMA fuel, which is also called MGO fuel.

[0011] According to the invention, at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, is adjusted with an offset in particular when the internal combustion engine is fired with an HFO fuel. In particular, a start of energisation for fuel injectors of a common rail fuel supply system and / or a storage pressure for at least one fuel storage unit of the common rail fuel supply system adjusted with an offset as operating parameter. The energization duration for the fuel injectors and the storage pressure for the or each fuel storage unit determine the fuel quantity which enters the cylinders of the internal combustion engine for each injection cycle. For this reason, these operating parameters are particularly advantageously suited to approximate an actual operating behavior that materialises subject to the firing of the internal combustion engine with an HFO fuel to a reference operating behaviour, which would materialise using the operating parameters, which were determined subject to fire the internal combustion engine with a DMA fuel, and subject to firing the internal combustion engine with the DMA fuel.

[0012] Accordingly, Fig. 2 again shows curve profiles for the cylinder pressure pz over the crankshaft angle cp and the heat quantity Qb given off by the fuel, namely again reference curve profiles 10, 11, which materialize subject to using a DMA fuel and the operating parameters applied in the application mode using the DMA fuel, as well as actual curve profiles 12', 13', which materialize subject to utilizing the invention.

[0013] By way of this offsetting of these operating parameters with an offset according to the invention, the actual operating behavior can be approximated according to the curve profiles 12', 13' to the reference operating behavior of the curve profiles 10, 11, so that, as is evident from a direct comparison of Figs. 1 and 2, deviations between the actual operating behavior and the reference operating behavior can be reduced or minimised.

[0014] Preferentially, the respect offset for the respective operating parameter is determined dependent on the current load of the internal combustion engine and / or dependent on the current rotational speed of the internal combustion engine and / or dependent on the current fuel quality. Particularly preferably, determining the respective offset takes place as a function of all three characteristic quantities.

[0015] Preferentially, for determining the respective offset for the respective operating parameter the procedure is such that initially, dependent on the current load of the internal combustion engine and dependent on the current rotational speed of the internal combustion engine, a current maximum offset for the respective operating parameter is determined.

[0016] For determining the current maximum offset dependent on the current load and the current rotational speed of the internal combustion engine, preferably a two-dimensional characteristic map is stored in the control device of the internal combustion engine, in which the current load and the current rotational speed of the internal combustion engine serve as input quantities, and in which the current maximum offset represents a starting quantity.

[0017] Furthermore, a current offset is then determined from the current maximum offset dependent on the current fuel quality, with which the respective operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, is then adjusted.

[0018] According to an advantageous further development, the current fuel quality follows from a viscosity control of the fuel connected upstream of the internal combustion engine. In the case of such a viscosity control, an actual value of the fuel viscosity is detected, compared with a set point value, wherein dependent on the deviation between the actual value and the set point value the fuel temperature is changed in order to approximate the actual value of the fuel viscosity to the set point value of the fuel viscosity. The fuel temperature adjusted during the fuel viscosity control provides information regarding the current fuel quality. The higher the fuel temperature of the fuel viscosity control, the lower is the fuel quality.

[0019] According to an advantageous further development of the invention it can be provided that in particular when the current fuel temperature of the fuel viscosity control is greater than an upper limit value, the current maximum offset is used for correcting the or each operating parameter of the internal combustion engine, which was determined dependent on the current load and / or dependent on the current rotational speed of the internal combustion engine.

[0020] If the fuel temperature of the fuel viscosity control is smaller than a lower limit value, no adjustment of the operating parameters, which were determined subject to firing the internal combustion engine with a DMA fuel, with an offset takes place. In this case, a zero offset then applies.

[0021] For fuel temperatures of the viscosity control, which lie between the upper limit value and the lower limit value, it can be provided to determine the current offset from the current maximum offset via interpolation, in particular a linear interpolation. This interpolation in this case takes place dependent on the current actual fuel temperature of the fuel viscosity control, which lies between the lower limit value and the upper limit value, i.e. dependent on the maximum offset of the upper limit value and the zero offset of the lower limit value.

[0022] As explained, the invention furthermore relates to a control device for carrying out the method. This control device is an engine control device of the internal combustion engine, which comprises hardware means and software means for carrying out the method. The hardware means are data interfaces in order to exchange data with the assemblies involved in carrying out the method according to the invention. Furthermore, the hardware means are a processor and a storage unit. The storage unit serves for data storage and the processor for data processing. The software means are program modules which are needed for carrying out the method according to the invention. Via its processor, the control device offsets at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, by an offset value stored in the storage unit, in order to approximate the actual operating behavior of the internal combustion engine to the referenced operating behavior of the same when the internal combustion engine is fired with an HFO fuel. This offset is preferentially determined in such a manner that dependent on the current load of the internal combustion engine and dependent on the current rotational speed of the internal combustion engine the control device determines a current maximum offset as starting quantity from a corresponding characteristic map. Dependent on the fuel quality, in particular dependent on a temperature of the fuel viscosity control, the control device then determines from the current maximum offset a current offset, which the control device uses for off setting the respective operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel.

[0023] The invention allows a particularly advantageous operation of an internal combustion engine with an HFO fuel, namely in particular even when an operating parameter was applied for the internal combustion engine using a DMA fuel. REFERENCE LIST

[0024]

Claims

1. A method for operating an internal combustion engine fired with a heavy fuel oil or an HFO fuel, wherein operating parameters for the internal combustion engine where applied in particular when for the parameter application the internal combustion engine is operated with a marine gas oil fuel or a DMA fuel, characterized in that in particular when the internal combustion engine is fired with an HFO fuel, at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, is adjusted with an offset.

2. The method according to claim 1,characterized in that as operating parameter a start of energisation for fuel injectors of a common rail fuel supply system is adjusted with an offset.

3. The method according to claim 1 or 2,characterized in that as operating parameter a storage pressure for a fuel storage unit of a common rail fuel supply system adjusted with an offset.

4. The method according to any one of the claims 1 to 3, characterized in that the respective offset for the respective operating parameter is determined dependent on the current load of the internal combustion engine and / or dependent on the current rotational speed of the internal combustion engine and / or dependent on the current fuel quality.

5. The method according to claim 4,characterized in that dependent on the current load and / or on the current rotational speed of the internal combustion engine a current maximum offset is determined.

6. The method according to claim 5,characterized in that dependent on the current fuel quality a current offset is determined from the current maximum offset, with which the respective operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, is offset.

7. A control device for operating an internal combustion engine fired with a heavy fuel oil fuel or an HFO fuel, wherein in the control unit operating parameters for the internal combustion engine are stored, which were determined subject to firing the internal combustion engine with a marine gas oil fuel or a DMA fuel, characterized in that in the control device at least one offset value is stored, and in that the control unit during the firing of the internal combustion engine with an HFO fuel, adjusts at least one operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel, with an offset value.

8. The control device according to claim 7,characterized in that the control device as operating parameter offsets an start of energisation for fuel injectors of a common rail fuel supply system and / or a storage pressure for a fuel storage unit of a common rail fuel supply system with an offset.

9. The control device according to claim 7 or 8,characterized in that the control unit determines the respective offset for the respective operating parameter dependent on the current load of the internal combustion engine and / or dependent on the current rotational speed of the internal combustion engine and / or dependent on the current fuel quality.

10. The control device according to claim 9,characterized in that the control device dependent on the current load and / or on the current rotational speed of the internal combustion engine determines a current maximum offset, and in that the control device dependent on the current fuel quality determines a current offset from the current maximum offset, with which the control unit adjusts the respective operating parameter, which was determined subject to firing the internal combustion engine with a DMA fuel.