Method and control unit for operating a spark-ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark-ignition mode

Abstract

Α method for operating a spark-ignition internal combustion engine (1) or a dual-fuel internal combustion engine (1) operated in the spark-ignition operating mode, wherein the internal combustion engine (1) to be operated is supplied with lubricating oil via an oil circuit (3), wherein a measurement value of the total base number and / or a measurement value of the oxidation of the lubricating oil currently used in the oil circuit (3) for the lubrication is detected, wherein dependent on the established measurement value of the total base number and / or dependent on the established measurement value of the oxidation an exchange oil quantity for the oil circuit (3) is determined, wherein currently used lubricating oil to an extent corresponding to the exchange oil quantity is removed from the oil circuit (3), wherein new lubricating oil to an extent corresponding to the exchange oil quantity is supplied to the oil circuit (3). Fig. 1

Description

METHOD AND CONTROL UNIT FOR OPERATING A SPARK-IGNITION INTERNAL COMBUSTION ENGINE OR A DUAL-FUEL INTERNAL COMBUSTION ENGINE OPERATED IN THE SPARK-IGNITION MODE The invention relates to a method for operating a spark-ignition internal combustion engine or a dual- fuel internal combustion engine operated in the spark- ignition mode. The invention, furthermore, relates to a control unit for operating a spark-ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark-ignition mode. The invention present here relates in particular to the range of so-called large engines or large internal combustion engines whose cylinders have piston diameters of more than 140 mm, in particular of more than 175 mm. Such large internal combustion engines are for example ship engines. Internal combustion engines have to be lubricated with lubricating oil during the operation. In the process, the lubricating oil is subject to an operation-related ageing. The ageing of the lubricating oil can result in that the lubricating oil loses the lubricating effect and damage of the internal combustion engine occurs. This has to be avoided. In the sector of so-called large engines it is usual that a part of the lubricating oil enters the combustion chambers of the cylinders where it is combusted together with the fuel to be combusted. This operation-related lubricating oil consumption is compensated in that the lubricating oil circuit is supplied with fresh lubricating oil from time to time, namely in particular when too much lubricating oil has been combusted in the region of the cylinders. Through the consumption or the combustion of the lubricating oil in the region of the cylinders and the replenishing of new lubricating oil for offsetting this oil consumption an adequate lubricating effect of the lubricating oil is mostly maintained in conventional large internal combustion engines so that it is not necessary to perform a complete oil change on the internal combustion engine. This would involve major expenditure. However, the combusting of the lubricating oil in the region of the cylinders results in high exhaust gas emissions. With ever more stringent emission regulations it has to be avoided that lubricating oil is combusted in the region of the cylinders. In this case, the replenishment of combusted lubricating oil carried out in conventional large internal combustion engines is reduced. It is therefore necessary in internal combustion engines in which as little as possible lubricating oil is combusted in the region of the cylinders for improving the exhaust gas emissions to perform a complete oil change in particular when the ageing of the lubricating oil has advanced too much. This is expensive. There is therefore a need to be able to do without a complete oil change also in such newer-type internal combustion engines in which in the region of the cylinders lubricating oil is only combusted to a minor extent. Starting out from this, the present invention is based on the object of creating a new type of method and control unit for operating a spark-ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark-ignition operating mode. This object is solved through a method for operating a spark-ignition internal combustion engine or a dual- fuel internal combustion engine operated in the spark- ignition operating mode. According to the invention, a measurement value of the total base number or a measurement value of the oxidation of the lubricating oil currently used in the oil circuit for the lubrication is detected. Dependent on the measurement value of the total base number and / or dependent on the measurement value of the oxidation, an exchange oil quantity for the oil circuit is determined. Currently used lubricating oil to the extent of the determined exchange oil quantity is removed from the oil circuit. Furthermore, new lubricating oil is supplied to the oil circuit to a degree corresponding to the determined exchange oil quantity. With the invention present here it is proposed for the first time to detect the total base number (TBN) and / or the oxidation of the lubricating oil used by measurement. Dependent on the respective detected measurement value, the exchange oil quantity for the internal combustion engine is determined. To the extent of the exchange oil quantity, lubricating oil is then specifically removed from the oil circuit, wherein new lubricating oil is supplied to the lubricating oil circuit to the same extent. By way of this, a lubricating oil consumption can then be reproduced without repercussions on exhaust gas emissions. The lubricating oil removed from the oil circuit is collected in a collection tank and can be subsequently disposed of or used further. Thus, a complete oil change can be omitted even in internal combustion engines in which due to the design little lubricating oil is combusted in the region of the cylinders. According to a further development of the invention, the measurement value of the total base number and the measurement value of the oxidation of the lubricating oil currently used in the oil circuit for the lubrication is detected, wherein dependent on the determined measurement value of the total base number and dependent on the determined measurement value of the oxidation the exchange oil quantity for the oil circuit is determined. Establishing the exchange oil quantity dependent on both measurements value, i.e. dependent both on the total base number and also dependent on the oxidation of the lubricating oil is particularly preferred in order to advantageously determine the exchange oil quantity for a spark- ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark- ignition mode. According to a further development of the invention, the exchange oil quantity for the oil circuit is determined dependent on the established measurement value of the total base number and / or dependent on the established measurement value of the oxidation as a function of the characteristic diagram or as a function of the characteristic curve. A determination of the exchange oil quantity as a function of the characteristic diagram or characteristic curve can be implemented particularly easily. For different support points of the measurement values of the total base number and / or of the oxidation, exchange oil quantities can be stored, wherein if required interpolation between individual measurement values can be carried out. The control unit for operating a spark-ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark-ignition operating mode is defined. Preferred further developments of the invention are obtained from 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: a diagram of an internal combustion engine. The invention relates to a method and to a control unit for operating a spark-ignition internal combustion engine or a dual-fuel internal combustion engine operated in the spark-ignition operating mode. Fig. 1 shows a highly schematised diagram of an internal combustion engine 1, which comprises multiple cylinders 2 and an oil circuit 3. The oil circuit 3 serves for supplying in particular the cylinders 2 of the internal combustion engine 1 with lubricating oil, wherein the lubricating oil is supplied to the cylinders 2 of the internal combustion engine 1 via an advance 4 and discharged from the same via a return 5. According to the invention present here it is proposed to detect a measurement value of the total base number (TBN) and / or a measurement value of the oxidation of the lubricating oil currently used in the oil circuit 3 for the lubrication. The measurement value of the total base number of the lubricating oil currently used in the oil circuit 3 for the lubrication is detected with the help of a first sensor 6. The measurement value of the oxidation of the lubricating oil currently used in the oil circuit 3 for the lubrication is detected with the help of a second sensor 7. The arrangement of the sensors 6 and 7 in the oil circuit is arbitrary. The two sensors 6 and 7 can also be combined into a unit. Dependent on the established measurement value of the total base number and / or dependent on the established measurement value of the oxidation, an exchange oil quantity for the oil circuit 3 is determined. To this end, the two sensors 6, 7 transmit their respective measurement value to a control unit 12, which dependent on the measurement value of the total base number and / or dependent on the measurement value of the oxidation determines the exchange oil quantity for the oil circuit 3. According to the invention, currently used lubricating oil is removed from the oil circuit 3 to an extent corresponding to the determined exchange oil quantity, furthermore, new lubricating oil to an extent corresponding to the determined exchange oil quantity is supplied to the oil circuit 3. The control unit 12 determines control variables as a function of which this oil exchange is carried out. Accordingly, Fig. 1 shows a first valve 8 which can be directly or indirectly controlled by the control unit 12 subject to the intermediate connection of a further control unit, in order to remove lubricating oil to the extent corresponding to the determined exchange oil quantity from the oil circuit 3 and collect the same in a collection tank 10. Furthermore, Fig. 1 shows a further valve 9 which can be likewise controlled emanating from the control unit 12 in order to supply the oil circuit 3 with new lubricating oil which is kept ready in a storage tank 11. With the invention it is proposed accordingly to remove a defined oil quantity from the oil circuit 3 dependent on the measurement value of the total base number and / or dependent on the measurement value of the oxidation of the lubricating oil currently used in the oil circuit 3 for the lubrication and exchange the same against new lubricating oil, namely to the extent of the exchange oil quantity established as a function of the respective measurement value. In this way, an oil consumption can be reproduced in the region of the cylinders 2. A defined exchange oil quantity of new oil can be continuously supplied in order to maintain the lubricating oil characteristics of the lubricating oil and render a complete oil change on the internal combustion engine 1 superfluous. The determination of the exchange oil quantity for the oil circuit dependent on the established measurement value of the total base number and / or dependent on the established measurement value of the oxidation takes place preferentially dependent on the characteristic diagram or characteristic curve. The characteristic map or the characteristic curve is stored in the control unit 12. For different support points of measurement values, exchange oil quantities are stored. Interpolation or extrapolation can be performed between individual support points. The method is employed with spark-ignition internal combustion engines or dual-fuel internal combustion engines operated in the spark-ignition operating mode. In particular, the exchange oil quantity is determined dependent on the two measurement values, i.e. dependent both on the total based number and also dependent on the oxidation of the lubricating oil. This procedure is particularly preferred for spark-ignition internal CA combustion engines or dual-fuel engines operated in the spark-ignition operating mode. The invention, furthermore, relates to a control unit 12 for carrying out the method. The control unit is equipped to carry out the method described above on the control side. To this end, the control unit 12 comprises data interfaces in order to exchange data with the assemblies involved in carrying out the method according to the invention, in particular with the sensors 6 and 7 and the valves 8 and 9. Furthermore, the control unit 12 as assembly on the hardware side comprises a processor for the data processing and a memory for data storage. Furthermore, the control unit 12 comprises means on the software side which are program modules which serve for carrying out the method according to the invention. The control unit 12 receives from the respective sensors 6, 7 the respective measurement value, preferentially the measurement value of the total base number from the sensor 6 and the measurement value of the oxidation from the sensor 7. Dependent on the respective measurement value, the control unit 12 determines the exchange oil quantity. Dependent on the exchange oil quantity, the control unit 12 emits control signals, as a function of which the oil exchange takes place, as a function of which accordingly currently used lubricating oil is removed from the oil circuit 3 and new lubricating oil supplied to the oil circuit 3. The invention relates in particular to the sector of so-called large engines or large internal combustion engines whose cylinders have piston diameters of more than 140 mm, in particular of more than 175 mm. Such large internal combustion engines are for example . marine engines. In the invention, these are embodied as spark-ignition internal combustion engines or as dual- fuel internal combustion engines operated in the spark- ignition operating mode. As fuel, such internal combustion engines combust gaseous fuel such as natural gas or liquid fuel such as methanol. Internal combustion engines combusting gaseous fuel are also referred to as gas engines. * 1 Internal combustion engine 2 Cylinder 3 Oil circuit 4 Advance 5 Return 6 Sensor 7 Sensor 8 Valve 9 Valve 10 Collection tank 11 Storage tank 12 Control unit •

Claims

<pat:ClaimStatement>CLAIMS< / pat:ClaimStatement> <pat:Claims com:id="claims"> <pat:Claim com:id="CLM-00001"> <pat:ClaimNumber>1< / pat:ClaimNumber> <pat:ClaimText>1. A method for operating a spark-ignition internal combustion engine (1) or a dual-fuel internal combustion engine (1) operated in the spark- ignition operating mode, wherein the internal combustion engine (1) to be operated is supplied with lubricating oil via an oil circuit (3), wherein a measurement value of the total base number and / or a measurement value of the oxidation of the lubricating oil currently used in the oil circuit (3) for the lubrication is detected, wherein dependent on the established measurement value of the total base number and / or dependent on the determined measurement value of the oxidation an exchange oil quantity for the oil circuit (3) is determined, wherein currently used lubricating oil to an extent corresponding to the exchange oil quantity is removed from the oil circuit (3) by opening a first valve, wherein new lubricating oil to an extent corresponding to the exchange oil quantity is applied to the oil circuit (3) by opening a second valve. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00002"> <pat:ClaimNumber>2< / pat:ClaimNumber> <pat:ClaimText>2. The method according to Claim 1, wherein the measurement value of the total base number and the measurement value of the oxidation of the lubricating oil currently used in the oil circuit (3) for the lubrication are detected, dependent on the established measurement value of the total base number and dependent on the established measurement value of the oxidation, the exchange oil quantity for the oil circuit (3) is determined. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00003"> <pat:ClaimNumber>3< / pat:ClaimNumber> <pat:ClaimText>3. The method according to Claim 1 or 2, wherein the measurement value of the total base number of the lubricating oil currently used in the oil circuit (3) for the lubrication is detected with the help of a first sensor (6). < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00004"> <pat:ClaimNumber>4< / pat:ClaimNumber> <pat:ClaimText>4. The method according to any one of the Claims 1 to 3, wherein the measurement value of the oxidation of the lubricating oil currently used in the oil circuit (3) for the lubrication is detected with the help of a second sensor (7). < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00005"> <pat:ClaimNumber>5< / pat:ClaimNumber> <pat:ClaimText>5. The method according to any one of the Claims 1 to 4, wherein the exchange oil quantity for the oil circuit (3) is determined dependent on the established measurement value of the total base number and / or dependent on the established measurement value of the oxidation as a function of a characteristic map or a characteristic curve. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00006"> <pat:ClaimNumber>6< / pat:ClaimNumber> <pat:ClaimText>6. A control unit (12) for operating a spark-ignition internal combustion engine (1) or a dual-fuel internal combustion engine (1) operated in the spark-ignition operating mode, wherein the control unit (12) receives from a first sensor (6) a measurement value of the total base number and / or from a second sensor (7) a measurement value of the oxidation of the lubricating oil currently used for lubricating the internal combustion engine, wherein the control unit (12) determines an exchange oil quantity dependent on the measurement value of the total base number and / or dependent on the measurement value of the oxidation, wherein the control unit (12) emits a first control signal, the first control signal configured to control a first valve, as a function of which currently used lubricating oil is removable from the oil circuit to an extent corresponding to the determined exchange oil quantity is removable, wherein the control unit (12) emits a second control signal, the second control signal configured to control a second valve, as a function of which new lubricating oil to an extent corresponding to the determined exchange oil quantity is suppliable to the oil circuit. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00007"> <pat:ClaimNumber>7< / pat:ClaimNumber> <pat:ClaimText>7. The control unit according to Claim 6, wherein the same is equipped to carry out the method on the control side according to any one of the Claims 1 to 5. < / pat:ClaimText> < / pat:Claim> < / pat:Claims>