DE102016200269A1 - Method for operating a liquid-cooled four-stroke internal combustion engine and four-stroke internal combustion engine for carrying out such a method - Google Patents

Abstract

The invention relates to a method for operating a liquid-cooled four-stroke internal combustion engine (1) comprising a cylinder block (1b) which is connected to at least one cylinder head (1a), a first coolant circuit (2) comprising at least one coolant jacket (2a) wherein for the formation of a water cooling (2) a supply line (2b) for supplying the at least one coolant jacket (2a) is provided with serving as a coolant water, and - a second coolant circuit (3) comprising at least one coolant jacket (3a), wherein for training an oil cooling (3) a supply line (3b) for supplying the at least one coolant jacket (3a) is provided with serving as a coolant oil. It should be shown a method by which the liquid cooling of the internal combustion engine (1) is improved. This is achieved with a method which is characterized in that below a first predefinable load Tdown, 1 - the water cooling (2) is deactivated, and - the internal combustion engine (1) using the oil cooling (3) is liquid-cooled.

Description

• – mindestens einem Zylinderkopf,
• – einem als obere Kurbelgehäusehälfte dienenden Zylinderblock, der mit dem mindestens einen Zylinderkopf verbunden ist,
• – einem ersten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Wasserkühlung eine Zuführleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Wasser vorgesehen ist, und
• – einem zweiten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Ölkühlung eine Versorgungsleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Öl vorgesehen ist.

The invention relates to a method for operating a liquid-cooled four-stroke internal combustion engine with

• At least one cylinder head,
• A cylinder block serving as an upper crankcase half, which is connected to the at least one cylinder head,
• A first coolant circuit comprising at least one coolant jacket, which is integrated in the composite of cylinder block and at least one cylinder head, wherein for supplying a water cooling, a supply line for supplying the at least one coolant jacket serving as a coolant water is provided, and
• - A second coolant circuit comprising at least one coolant jacket, which is integrated in the composite of cylinder block and at least one cylinder head, wherein for the formation of oil cooling, a supply line for supplying the at least one coolant jacket is provided with serving as a coolant oil.

Furthermore, the invention relates to a liquid-cooled four-stroke internal combustion engine for carrying out such a method.

A four-stroke internal combustion engine of the type mentioned is used as a motor vehicle drive. In the context of the present invention, the term internal combustion engine includes diesel engines and gasoline engines, but also hybrid internal combustion engines, d. H. Internal combustion engines, which are operated with a hybrid combustion process, and hybrid drives, which in addition to the internal combustion engine include a drive motor-connectable with the electric motor, which receives power from the internal combustion engine or emits additional power as a switchable auxiliary drive.

Internal combustion engines have a cylinder block and at least one cylinder head, which are connected to form the individual cylinders.

Modern internal combustion engines for motor vehicle drives are operated almost exclusively according to a four-stroke work process. As part of the charge cycle, the exhaust gases are exhausted via the exhaust ports and filled with air via the intake ports. In order to control the charge cycle, an internal combustion engine requires control means and actuators to operate these controls. To control the charge cycle, four-stroke engines use almost exclusively globe valves as control members, which perform an oscillating lifting movement during operation of the internal combustion engine and in this way release and close the inlet openings and outlet openings. The required for the movement of a valve valve actuating mechanism including the valve itself is referred to as a valve train. The at least one cylinder head is usually used to accommodate the valve trains.

It is the task of the valve drive to release the corresponding inlet opening or outlet opening of the cylinder in good time or to close, with a quick release of the largest possible flow cross section is sought to keep the throttle losses in the incoming and outflowing gas flows low and the best possible Filling the cylinder or an effective, d. H. To ensure complete removal of the exhaust gases. Therefore, the cylinders are also often equipped with multiple inlet openings and outlet openings.

The intake pipes leading to the intake ports and the exhaust pipes connecting to the exhaust ports are at least partially integrated in the cylinder head in the prior art. The intake pipes of the intake system or exhaust pipes of the exhaust gas removal system of the cylinders are regularly combined to form a common total intake pipe or exhaust gas line or in groups to several total intake pipes or Gesamtansaugleitungen. The merging of the lines is generally and in the context of the present invention referred to as a manifold.

The cylinder block has a corresponding number of cylinder bores for receiving the pistons or the cylinder tubes. The piston serves to transmit the gas forces generated by the combustion to the crankshaft, wherein the oscillating lifting movement of the pistons is transformed into a rotary rotational movement of the crankshaft. The crankshaft mounted in the crankcase transmits the torque to the drive train. The piston head forms part of the combustion chamber inner wall and, together with the piston rings, seals the combustion chamber against the cylinder block or the crankcase so that no combustion gases or combustion air enter the crankcase and no oil enters the combustion chamber.

In general, and in the context of the present invention, the upper crankcase half is formed by the cylinder block. The crankcase is regularly supplemented by a lower crankcase half, which can be mounted on the upper half of the crankcase and serves as an oil sump. In this case, the upper crankcase half for receiving the Oil pan, ie the lower crankcase half, a flange on.

For receiving and supporting the crankshaft at least two bearings are provided in the crankcase, which are usually made in two parts and each include a bearing saddle and connectable to the bearing saddle bearing cap. The crankshaft is mounted in the region of the crankshaft journals which are arranged at a distance from one another along the crankshaft axis and are generally designed as thickened shaft shoulders. This bearing cap and bearing saddles can be used as separate components or in one piece with the crankcase, d. H. the crankcase halves are formed. Between the crankshaft and the bearings bearing shells can be arranged as intermediate elements.

When assembled, each bearing saddle is connected to the corresponding bearing cap. In each case a bearing saddle and a bearing cap form - if appropriate in cooperation with bearing shells as intermediate elements - a bore for receiving a crankshaft journal. The holes are usually with engine oil, d. H. Lubricating oil supplied, so that ideally forms between the inner surface of each bore and the associated crankshaft journal with rotating crankshaft - similar to a plain bearing - a viable lubricating film. Alternatively, a bearing can also be formed in one piece, for example in a built crankshaft.

To supply the bearings with oil, a pump for delivering engine oil to the at least two bearings is provided, the pump via oil circuit a main oil gallery, supplied by the channels to the at least two camps, supplied with engine oil. To form the main oil gallery, a main supply channel is often provided in the cylinder block, which is aligned along the longitudinal axis of the crankshaft.

The pump is supplied in the prior art via suction, which leads from an oil pan to the pump, coming from the oil pan engine oil and has a sufficiently large flow rate, d. H. ensure a sufficiently high delivery volume, and for a sufficiently high oil pressure in the supply system, d. H. in the oil cycle, especially in the main oil gallery.

Another consumer to be supplied with oil in the above sense, for example, be the camshaft receiver. The statements already made with regard to the crankshaft bearing apply analogously. Also, the camshaft receiving is usually supplied with lubricating oil, including a supply channel is provided.

Further consumers may be, for example, the bearings of a connecting rod or an optional balancing shaft. Also consumer in the aforementioned sense is also a spray oil cooling, which the piston crown for the purpose of cooling by means of nozzles from below, d. H. crankcase side, wetted with engine oil and thus oil needs, d. H. must be supplied with oil.

A hydraulically operable camshaft phaser or other valve train components, for example, for hydraulic valve clearance, also have a need for engine oil and require an oil supply.

No consumers in the aforementioned sense are provided in the supply line oil filter or oil cooler and the oil-carrying lines as such. Although these components of the oil circuit are supplied with engine oil. Due to the principle, however, an oil cycle entails the use of these components, which are exclusively tasks, i. H. Have functions that affect the oil as such, whereas a consumer first makes the oil cycle necessary.

The friction in the consumers to be supplied with oil, for example, the bearings of the crankshaft or between the piston and cylinder tube, depends significantly on the viscosity and thus of the temperature of the oil provided and contributes to fuel consumption of the internal combustion engine.

Basically, efforts are made to minimize fuel consumption. In addition to an improved, d. H. more effective combustion is the reduction of friction in the foreground of the efforts. A reduced fuel consumption also contributes to a reduction in pollutant emissions.

With regard to a reduction of the friction power, rapid heating of the engine oil and rapid heating of the internal combustion engine, especially after a cold start, are expedient. A rapid heating of the engine oil during the warm-up phase of the internal combustion engine ensures a correspondingly rapid decrease in viscosity and thus a reduction in the friction or friction.

Reducing the friction loss through rapid heating of the engine oil is made more difficult by the fact that the cylinder block or the cylinder head are thermally highly stressed components which require effective cooling and are therefore often equipped with coolant jackets to form a liquid cooling system. The heat balance of a liquid-cooled internal combustion engine is primarily dominated by this cooling. The interpretation The cooling takes place with regard to the protection against overheating and not with a view to the fastest possible heating of the engine oil after a cold start.

The equipment of the internal combustion engine with a liquid cooling requires the arrangement of the coolant through the cylinder head and / or the cylinder block leading coolant channels, d. H. at least one coolant jacket. The coolant, usually with additives or glycol-added water, is thereby conveyed by means of a pump arranged in the cooling circuit, so that it circulates in the coolant jacket. The heat emitted to the coolant heat is dissipated in this way from the interior of the cylinder block or cylinder head and withdrawn in the rule in a heat exchanger the coolant again.

Water has the advantage over other coolants that it is non-toxic, readily available and inexpensive and also has a very high heat capacity, which is why water is suitable for the removal and removal of very large amounts of heat, which is generally considered advantageous. A disadvantage, however, is the associated with water corrosion of the acted upon with coolant components, and the comparatively low maximum allowable coolant temperature of about 95 ° C, which significantly determines the temperature difference between the coolant and the components to be cooled and thus the heat transfer.

If the internal combustion engine, in particular the cylinder block, less heat to be withdrawn, the use of other cooling fluids can be effective, such as oil. Oil has a lower heat capacity compared to water and can be stronger, d. H. be heated to higher temperatures, whereby the cooling capacity can be reduced. The problem of corrosion is eliminated. In addition, oil can easily come into contact with components, in particular moving components, without jeopardizing the functionality of the internal combustion engine.

An oil-cooled internal combustion engine describes, for example, the German Offenlegungsschrift DE 199 40 144 A1 ,

In addition, the use of oil as a coolant for the cooling circuit further advantages, in particular the advantage that an oil cooling and the associated coolant jackets can be formed contiguous with the oil supply of the engine, d. H. a common contiguous oil circuit is formed. The oil is heated faster after a cold start due to the flow through the at least one coolant jacket, whereby the warm-up phase can be shortened. The at least one coolant jacket of the oil cooling is a consumer in the sense mentioned above, which makes an oil circuit first necessary. The coolant jacket has the task to cool, and not - as a line - only to lead or guide the oil.

The dissipated by means of liquid cooling heat has a significant influence on the efficiency of the internal combustion engine or fuel consumption. Basically, under thermodynamic aspects as little as possible of the chemically bound in the fuel energy should be dissipated as heat.

In view of the foregoing, it is an object of the present invention to provide a method according to the preamble of claim 1, with which the liquid cooling of a four-stroke internal combustion engine is improved.

Another object of the present invention is to provide a liquid-cooled four-stroke internal combustion engine for carrying out such a method.

• – mindestens einem Zylinderkopf,
• – einem als obere Kurbelgehäusehälfte dienenden Zylinderblock, der mit dem mindestens einen Zylinderkopf verbunden ist,
• – einem ersten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Wasserkühlung eine Zuführleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Wasser vorgesehen ist, und
• – einem zweiten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Ölkühlung eine Versorgungsleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Öl vorgesehen ist,

das dadurch gekennzeichnet ist, dass bei Unterschreiten einer ersten vorgebbaren Last T_down,1

• – die Wasserkühlung deaktiviert wird, und
• – die Brennkraftmaschine unter Verwendung der Ölkühlung flüssigkeitsgekühlt wird.

The first sub-task is solved by a method for operating a liquid-cooled four-stroke internal combustion engine with

• At least one cylinder head,
• A cylinder block serving as an upper crankcase half, which is connected to the at least one cylinder head,
• A first coolant circuit comprising at least one coolant jacket, which is integrated in the composite of cylinder block and at least one cylinder head, wherein for supplying a water cooling, a supply line for supplying the at least one coolant jacket serving as a coolant water is provided, and
• A second coolant circuit comprising at least one coolant jacket which is integrated in the composite of the cylinder block and at least one cylinder head, wherein a supply line for supplying the at least one coolant jacket with oil serving as coolant is provided for forming an oil cooling,

which is characterized in that falls below a first predetermined load T _{down, 1}

• - the water cooling is deactivated, and
• - The internal combustion engine is liquid-cooled using the oil cooling.

The liquid-cooled internal combustion engine, which is the subject of the present invention, has water cooling and oil cooling, which preferably forms a common oil circuit with the oil supply. To the training of Water cooling or oil cooling is integrated at least one coolant jacket in the cylinder block and / or the at least one cylinder head.

According to the method according to the invention, the water cooling is deactivated at low loads and the internal combustion engine is cooled by means of oil cooling.

By doing so, less heat is extracted from the engine at low loads because oil has a lower heat capacity and can be heated to higher temperatures, thereby reducing cooling performance. By increasing the coolant temperature, the temperature of the component to be cooled, in particular of the cylinder head or cylinder block, also increases. The heat transfer into the coolant is reduced and the wall heat losses decrease. Consequently, less of the energy chemically bound in the fuel is dissipated as heat and the efficiency of the internal combustion engine increases.

The method according to the invention also proves to be advantageous during the warm-up phase, in particular after a cold start, when rapid heating of the internal combustion engine is desired in order to heat the engine oil and reduce the friction or friction power. By using the oil cooling of the engine less heat is removed and the heating of the oil is supported or accelerated.

With the method according to the invention a method according to the preamble of claim 1 is shown, with which the liquid cooling of a four-stroke internal combustion engine is improved. The method according to the invention thus solves the first sub-task on which the invention is based.

The at least one coolant jacket of the oil cooling is preferably adjacent to thermally higher loaded areas of the internal combustion engine, d. H. the cylinder block or the cylinder head, arranged, the so-called hot-spots.

The thermally higher loaded areas are regularly arranged adjacent to a cylinder or exhaust side in the vicinity of the outlet openings and the exhaust pipes, d. H. at the points where the combustion and the hot exhaust gases preferentially introduce heat into the components.

Advantageously, variants in which the oil cooling with the oil supply of the internal combustion engine forms a common oil circuit, so that the pump and the lines of the oil circuit can be used to provide the at least one coolant jacket of oil cooling with oil.

Further advantageous embodiments of the method according to the invention are discussed in connection with the subclaims.

Advantageous embodiments of the method in which the water cooling is deactivated by the coolant flow is prevented by the at least one coolant jacket. According to this variant, the flow of water through the at least one coolant jacket is adjusted. Due to the lack of flow velocity of the coolant eliminates heat transfer due to convection. The coolant is in the coolant circuit, which is why the coolant itself no heat in a heat exchanger can be withdrawn and the coolant heats up further. The flow through the at least one coolant jacket can be prevented by means of shut-off.

In this connection, however, embodiments of the method may advantageously be advantageous in which the coolant flow through the at least one coolant jacket is prevented by switching off a pump for conveying water belonging to the water cooling system.

In individual cases, the pump can not only be switched on and off, but set the pump power. Then influence on the flow rate and the coolant flow rate, d. H. the delivery volume, be taken. In this way, the coolant flow through the at least one coolant jacket and thus the heat transfer by convection can be adjusted. The water cooling can then also be deactivated by reducing the coolant flow or the flow rate.

Embodiments of the method may also be advantageous in which the water cooling is deactivated by at least partially emptying the at least one coolant jacket by discharging coolant.

In the present case, the amount of coolant present in the at least one coolant jacket is varied in order to influence the amount of heat withdrawn from the internal combustion engine. In this case, by discharging at least a portion of the water, the cooling capacity is reduced to disable the water cooling. As a result of the reduced cooling capacity and the consequent reduced heat dissipation, the cylinder block or the cylinder head heats up and thus also the oil in the internal combustion engine.

With the discharge of water is inherently not only the amount of coolant in the at least one coolant jacket of the water cooling, but also the heat-transferring surface between coolant and component influenced or reduced. The ability to drain water from the water cooling system allows demand-based cooling of the internal combustion engine.

In order to apply the above concept, a discharge point for draining the water, a storage container, a feed pump and the like must be provided.

In this connection, embodiments of the method are advantageous in which, for the purpose of deactivating the water cooling, coolant is discharged via the discharge line into a storage container. Preferably, the storage container is arranged geodetically deeper in the installed position than the at least one coolant jacket of the water cooling, so that the discharge of the water can be done by gravity.

Also advantageous in this context are embodiments of the method in which an additional pump is provided in the drain line for the purpose of conveying coolant both into the storage container and out of the storage container.

Embodiments of the method may be advantageous in which the water cooling is deactivated by bypassing a heat exchanger belonging to the water cooling via bypass line. Then no heat is removed from the water in the heat exchanger. The optionally further circulating in the circulation water heats up steadily.

Advantageous embodiments of the method in which the water cooling to form a water cycle with a discharge line for discharging the coolant, a return line, which branches off from the discharge line and opens into the supply line, and a heat exchanger is equipped.

Also advantageous in this context are embodiments of the method in which the heat exchanger is provided in the return line, wherein a bypass line is provided for bypassing the heat exchanger.

Embodiments of the method are advantageous in which an oil pan which can be mounted on the upper crankcase half and serves as a lower crankcase half is provided for collecting and storing oil, wherein the at least one coolant jacket of the oil cooling is supplied by oil pump via supply line with oil originating from the oil pan and on the outlet side a return line is provided, with which the at least one coolant jacket is connected to form an oil circuit with the oil pan.

Also advantageous in this context are embodiments of the method in which an oil cooler is provided in the oil circuit.

Embodiments in which a charge is provided are advantageous.

For operating a liquid-cooled four-stroke internal combustion engine, in which each cylinder has at least one outlet opening for discharging the exhaust gases via Abgasabführsystem and at least one inlet opening for supplying air via the intake system, embodiments of the method are advantageous, which are characterized in that for the purpose of charging at least an exhaust gas turbocharger is provided which comprises a turbine arranged in the exhaust gas removal system and a compressor arranged in the intake system.

The charging of internal combustion engines is becoming increasingly important and is a suitable means to increase the capacity of an internal combustion engine with unchanged displacement or to reduce the displacement at the same power. In any case, the charging leads to an increase in space performance and a lower power mass. If the cubic capacity is reduced, the load spectrum can be shifted to higher loads at the same vehicle boundary conditions, where the specific fuel consumption is lower. The charging of an internal combustion engine thus supports the efforts to minimize fuel consumption, d. H. to improve the efficiency of the internal combustion engine.

Supercharged internal combustion engines are preferably equipped with a charge air cooling, with which the compressed charge air is cooled before entering the cylinder. As a result, the density of the charge air supplied continues to increase. The cooling also contributes in this way to a compression and better filling of the combustion chambers, d. H. to an improved degree of filling, at. It may be advantageous to equip the intercooler with a bypass line in order to bypass the intercooler when necessary, for example, after a cold start.

The advantage of an exhaust gas turbocharger, for example in comparison to a mechanical supercharger, is that no mechanical connection is required for transmitting power between the supercharger and the internal combustion engine. While a mechanical supercharger obtains the energy required for its drive from the internal combustion engine and thus reduces the power provided and in this way adversely affects the efficiency, The exhaust gas turbocharger uses the exhaust gas energy of the hot exhaust gases.

The design of the exhaust turbocharger often causes difficulties, in principle, a noticeable increase in performance in all speed ranges is sought. However, a torque drop is regularly observed when falling below a certain speed.

The torque characteristic of a supercharged internal combustion engine can be improved by different measures, for example by using a plurality of exhaust gas turbochargers arranged in series and / or in parallel, optionally in combination with one or more mechanical superchargers and / or auxiliary electric drives.

For operating a liquid-cooled four-stroke internal combustion engine having at least two cylinders, in which at least two cylinders are configured in such a way that these cylinders form at least two groups each having at least one cylinder, wherein the at least one cylinder of a first group even at partial shutdown Embodiments of the method are advantageous, which are characterized in that falls below a second predetermined load T _{down, 2 of} the at least one cylinder of the second is in the cylinder in operation befindlicher cylinder and the at least one cylinder of a second group is designed as a load-dependent switchable cylinder Group is switched off.

In the development of internal combustion engines, it is a fundamental goal to minimize fuel consumption, with an improved overall efficiency in the foreground of the efforts.

The fuel consumption and thus the efficiency, especially in gasoline engines, d. H. in spark-ignition internal combustion engines. The reason for this lies in the basic working method of the gasoline engine. The load control is usually carried out by means of a throttle valve provided in the intake system. By adjusting the throttle, the pressure of the intake air behind the throttle valve can be reduced more or less. The farther the throttle is closed, d. H. the more this obstructs the intake system, the higher the pressure loss of the intake air across the throttle and the lower the pressure of the intake air downstream of the throttle and before the intake into the at least two cylinders, d. H. Combustion chambers. With a constant combustion chamber volume, the air mass, d. H. the quantity will be set. This also explains why the quantity control proves to be disadvantageous especially in part-load operation, because low loads require high throttling and pressure reduction in the intake system, whereby the charge exchange losses increase with decreasing load and increasing throttling.

In order to reduce the losses described, various strategies have been developed for de-throttling a spark-ignited internal combustion engine. One approach to dethrottling the gasoline engine is, for example, an Otto engine working method with direct injection. The direct injection of the fuel is a suitable means for realizing a stratified combustion chamber charge. The direct injection of the fuel into the combustion chamber thus allows within certain limits a quality control of the gasoline engine. Another way to optimize the combustion process of a gasoline engine, is the use of an at least partially variable valve train. Throttle-free and thus lossless load control is already possible if the closing time of the intake valve and the intake valve lift can be varied. The mixture mass flowing into the combustion chamber during the intake process is then controlled not by means of a throttle valve but via the intake valve lift and the opening duration of the intake valve.

Another solution for de-throttling a gasoline engine offers the cylinder deactivation, d. H. the shutdown of individual cylinders in certain load ranges. The efficiency of the gasoline engine in partial load operation can be improved by a partial shutdown, d. H. be increased, because the shutdown of a cylinder of a multi-cylinder internal combustion engine increases the load of the remaining still in operation cylinder at constant engine power, so that the throttle for introducing a larger air mass in these cylinders can be opened or must, resulting in a total Entdrosselung the internal combustion engine is achieved. The continuously operating cylinders also operate during partial shutdown in the area of higher loads, where the specific fuel consumption is lower. The load collective is shifted to higher loads.

The further operated during the partial shutdown cylinder also have due to the larger air mass supplied or mixture mass improved mixture formation.

Further efficiency advantages result from the fact that a deactivated cylinder as a result of the lack of combustion no wall heat losses generated as a result of heat transfer from the combustion gases to the combustion chamber walls.

Although diesel engines, ie self-igniting internal combustion engines, due to the applied quality control originally higher efficiency, ie a lower fuel consumption, have as gasoline engines, where the load - as described above - by throttling or quantity control on the filling of the cylinder is set, also exists Diesel engines improvement potential and need for improvement in terms of fuel consumption and efficiency. A concept for reducing fuel consumption is also in diesel engines, the cylinder deactivation, ie the shutdown of individual cylinders in certain load ranges. The partial shutdown in diesel engines should also prevent the fuel-air mixture under the quality scheme with decreasing load by reducing the amount of fuel used too much.

Embodiments of the method in which at least one operating cylinder of the internal combustion engine is operated according to a two-stroke operating method when a third predefinable load T _{down, 3 is operated are} at least advantageous.

It may be particularly advantageous to operate the internal combustion engine during a partial shutdown in accordance with a two-stroke operating method in which, compared to the four-stroke operating method, the power strokes of the suction of air and expulsion of exhaust gas omitted. Instead, the charge is changed by blowing in air via at least one further inlet opening of the cylinder.

The transfer of the internal combustion engine into the two-stroke operation has the advantage during partial shutdown that the ignition frequency with which the ignition is initiated - in the cylinders in operation - does not change if it is assumed that half of the cylinders the internal combustion engine is switched off during partial shutdown. As a result, advantages in terms of noise emission and torsional vibration excitation of the crankshaft can be achieved. Speed fluctuations of the internal combustion engine, which are undesirable, are avoided. In addition, the two-stroke work process is characterized by a high power density.

The partial shut-off and the two-stroke operation applied during the partial shut-down require adapted actuation of the inlet openings and outlet openings of the cylinders or the valves and valve trains belonging to the openings.

The predefinable loads T _{down, 1} , T _{down, 2} , T _{down, 3} can be the same size, but also differ. In addition, these loads may be dependent on operating parameters of the internal combustion engine, such as the speed, the coolant temperature, ie the water temperature or oil temperature, the engine temperature and / or the like.

• – mindestens einem Zylinderkopf,
• – einem als obere Kurbelgehäusehälfte dienenden Zylinderblock, der mit dem mindestens einen Zylinderkopf verbunden ist,
• – einem ersten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Wasserkühlung eine Zuführleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Wasser vorgesehen ist, und
• – einem zweiten Kühlmittelkreislauf umfassend mindestens einen Kühlmittelmantel, der in dem Verbund aus Zylinderblock und mindestens einem Zylinderkopf integriert ist, wobei zur Ausbildung einer Ölkühlung eine Versorgungsleitung zur Versorgung des mindestens einen Kühlmittelmantels mit als Kühlmittel dienendem Öl vorgesehen ist,

die dadurch gekennzeichnet ist, dass bei mindestens einem in Betrieb befindlichen Zylinder der flüssigkeitsgekühlten Brennkraftmaschine ein Zwei-Takt-Arbeitsverfahren anwendbar ist.The second sub-problem underlying the invention, namely to provide an internal combustion engine for carrying out a method of the type described above, is achieved by a liquid-cooled four-stroke internal combustion engine

• At least one cylinder head,
• A cylinder block serving as an upper crankcase half, which is connected to the at least one cylinder head,
• A first coolant circuit comprising at least one coolant jacket, which is integrated in the composite of cylinder block and at least one cylinder head, wherein for supplying a water cooling, a supply line for supplying the at least one coolant jacket serving as a coolant water is provided, and
• A second coolant circuit comprising at least one coolant jacket which is integrated in the composite of the cylinder block and at least one cylinder head, wherein a supply line for supplying the at least one coolant jacket with oil serving as coolant is provided for forming an oil cooling,

which is characterized in that in at least one operating cylinder of the liquid-cooled internal combustion engine, a two-stroke working method is applicable.

What has already been said for the method according to the invention also applies to the liquid-cooled internal combustion engine according to the invention, which is why reference is generally made at this point to the statements made above with regard to the method. The various internal combustion engines sometimes require different process variants and vice versa.

In principle, measures can be provided to drain the oil from the at least one coolant jacket of the oil cooling. The oil pan could serve as a storage container for storing the drained oil.

In the following the invention with reference to an embodiment of the liquid-cooled four-stroke internal combustion engine according to 1 explained in more detail. Hereby shows:

1 schematically and fragmentarily a cylinder of a first embodiment of the liquid-cooled four-stroke internal combustion engine together with liquid cooling, partially cut.

1 shows schematically and fragmentarily a cylinder 1c a first embodiment of the liquid-cooled four-stroke internal combustion engine 1 including liquid cooling 2 . 3 , partially cut.

The internal combustion engine 1 has a cylinder block 1b and a cylinder head 1a leading to the formation of the cylinder 1c connected to each other.

Every cylinder 1c has two inlet openings for supplying air via the intake system, wherein a suction line connects to each inlet opening (not shown). To exhaust the exhaust gases via Abgasabführsystem is every cylinder 1c with two outlet openings 1d fitted. Every cylinder 1c is also equipped with an injector 4 equipped for injection of fuel. In addition, each cylinder has 1c over a piston 5 which is movable along a piston longitudinal axis between a bottom dead center UT and a top dead center OT.

The internal combustion engine 1 has both a water cooling 2 as well as an oil cooling 3 ,

A first coolant circuit 2 forms the water cooling 2 and includes one in the cylinder block 1b integrated coolant jacket 2a and one in the cylinder head 1a integrated coolant jacket 2a , wherein for supplying the coolant jackets 2a with a water-glycol mixture, a supply line 2 B is provided.

A second coolant circuit 3 forms the oil cooling 3 and includes several in the cylinder head 1a integrated coolant jackets 3a , which are adjacent to thermally highly loaded areas of the cylinder head 1a are arranged, namely in the vicinity of the outlet openings 1d and the exhaust pipes, ie at the locations where preferably heat in the cylinder head 1a is initiated. The coolant jackets 3a be by pump via supply line 3b supplied with oil derived from an oil pan, which serves as a coolant. The oil sump is used to collect and store the oil. On the outlet side are the coolant jackets 3a via return line with the oil pan in conjunction, leaving an oil circuit 3 is formed, in which other consumers can be arranged, via the oil circuit 3 be supplied with oil.

Falls below a predetermined load is the water cooling 2 deactivated and the internal combustion engine 1 using oil cooling 3 liquid cooled.

In the present case, the water cooling 2 deactivated by the coolant jackets 2a be emptied by draining coolant at least partially. By draining the water is in the Kühlmittelmänteln 2a located coolant quantity and thus the cooling capacity of the water cooling 2 reduced. With the discharge of water and the heat transfer surface is reduced.

The water is via drainage pipe 2e in a storage container 2d drained, which is presently arranged geodetically lower than the coolant jackets 2a the water cooling 2 so that the draining of the water is assisted by gravity. For the purpose of pumping the water into both the storage container 2d into and out of the storage container 2d out is an extra pump 2c in the drainage line 2e intended.

LIST OF REFERENCE NUMBERS

1

 Internal combustion engine

1a

 cylinder head

1b

 cylinder block

1c

 cylinder

1d

 outlet

2

 first coolant circuit, water cooling, water circulation

2a

 Coolant jacket

2 B

 feed

2c

 additional pump

2d

 storage container

2e

 drain line

3

 second coolant circuit, oil cooling, oil circuit

3a

 Coolant jacket

3b

 supply line

4

 injection

5

 piston

T _{down, 1}

 first definable load

T _{down, 2}

 second predetermined load

T _{down, 3}

 third predetermined load

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19940144 A1 [0025]

Claims (15)

Method for operating a liquid-cooled four-stroke internal combustion engine ( 1 ) with - at least one cylinder head ( 1a ), - a cylinder block serving as an upper crankcase half ( 1b ), which with the at least one cylinder head ( 1a ), - a first coolant circuit ( 2 ) comprising at least one coolant jacket ( 2a ), which in the composite of cylinder block ( 1b ) and at least one cylinder head ( 1a ) is integrated, whereby for the formation of a water cooling ( 2 ) a supply line ( 2 B ) for supplying the at least one coolant jacket ( 2a ) is provided with serving as a coolant water, and - a second coolant circuit ( 3 ) comprising at least one coolant jacket ( 3a ), which in the composite of cylinder block ( 1b ) and at least one cylinder head ( 1a ) is integrated, whereby to form an oil cooling ( 3 ) a supply line ( 3b ) for supplying the at least one coolant jacket ( 3a ) provided with serving as a coolant oil, characterized in that falls below a first predetermined load T _{down, 1} - the water cooling ( 2 ) is deactivated, and - the internal combustion engine ( 1 ) using oil cooling ( 3 ) is liquid cooled. Method according to claim 1, characterized in that the water cooling ( 2 ) is deactivated by a coolant flow through the at least one coolant jacket ( 2a ) is prevented. A method according to claim 2, characterized in that the coolant flow through the at least one coolant jacket ( 2a ) is stopped by a water cooling ( 2 ) belonging pump for pumping water is switched off. Method according to claim 1, characterized in that the water cooling ( 2 ) is deactivated by the at least one coolant jacket ( 2a ) is emptied by draining coolant at least partially. Method according to claim 4, characterized in that for the purpose of deactivating the water cooling ( 2 ) Coolant via drain line ( 2e ) in a storage container ( 2d ) is drained. A method according to claim 5, characterized in that for the purpose of promoting coolant both in the storage container ( 2d ) as well as from the storage container ( 2d ) an extra pump ( 2c ) in the drain line ( 2e ) is provided. Method according to claim 1, characterized in that the water cooling ( 2 ) is deactivated by a water cooling ( 2 ) belonging heat exchanger is bypassed via bypass line. Method according to one of the preceding claims, characterized in that the water cooling ( 2 ) for the formation of a water cycle ( 2 ) With a discharge line for discharging the coolant, a return line which branches off from the discharge line and opens into the supply line, and is equipped with a heat exchanger. A method according to claim 8, characterized in that the heat exchanger is provided in the return line, wherein a bypass line for bypassing the heat exchanger is provided. Method according to one of the preceding claims, characterized in that an oil sump which can be mounted on the upper crankcase half and serves as a lower crankcase half for collecting and storing oil is provided, wherein the at least one coolant jacket ( 3a ) of oil cooling ( 3 ) by means of oil pump via supply line ( 3b ) is supplied with oil coming from the oil sump and the outlet side, a return line is provided, with which the at least one coolant jacket ( 3a ) for the formation of an oil circuit ( 3 ) is connected to the oil pan. Method according to claim 10, characterized in that in the oil circuit ( 3 ) An oil cooler is provided. Method according to one of the preceding claims for operating a liquid-cooled four-stroke internal combustion engine ( 1 ), where each cylinder ( 1c ) at least one outlet opening ( 1d ) for discharging the exhaust gases via Abgasabführsystem and at least one inlet opening for supplying air via intake system, characterized in that for the purpose of charging at least one exhaust gas turbocharger is provided, which comprises a arranged in Abgasabführsystem turbine and arranged in the intake compressor. Method according to one of the preceding claims for operating a liquid-cooled four-stroke internal combustion engine ( 1 ) with at least two cylinders ( 1c ), where at least two cylinders ( 1c ) are configured in such a way that these cylinders ( 1c ) at least two groups each having at least one cylinder ( 1c ), wherein the at least one cylinder ( 1c ) a first group also at partial shutdown of the internal combustion engine ( 1 ) operating cylinder ( 1c ) and the at least one cylinder ( 1c ) of a second group as a load-dependent switchable cylinder ( 1c ) is trained, characterized in that falls below a second predetermined load T _{down, 2 of} the at least one cylinder ( 1c ) of the second group is turned off. Method according to one of the preceding claims, characterized in that falls below a third predetermined load T _{down, 3} at least one in-service cylinder ( 1c ) of the internal combustion engine ( 1 ) is operated according to a two-stroke working method. Liquid-cooled four-stroke internal combustion engine ( 1 ) for performing a method according to one of the preceding claims with - at least one cylinder head ( 1a ), - a cylinder block serving as an upper crankcase half ( 1b ), which with the at least one cylinder head ( 1a ), - a first coolant circuit ( 2 ) comprising at least one coolant jacket ( 2a ), which in the composite of cylinder block ( 1b ) and at least one cylinder head ( 1a ) is integrated, whereby for the formation of a water cooling ( 2 ) a supply line ( 2 B ) for supplying the at least one coolant jacket ( 2a ) is provided with serving as a coolant water, and - a second coolant circuit ( 3 ) comprising at least one coolant jacket ( 3a ), which in the composite of cylinder block ( 1b ) and at least one cylinder head ( 1a ) is integrated, whereby to form an oil cooling ( 3 ) a supply line ( 3b ) for supplying the at least one coolant jacket ( 3a ) is provided with serving as a coolant oil, characterized in that at least one operating cylinder ( 1c ) of the internal combustion engine ( 1 ) a two-stroke working method is applicable.

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