EP2557292A1 - Liquid cooled internal combustion engine equipped with an exhaust gas turbo charger - Google Patents

Abstract

The boosted liquid-cooled internal combustion engine (1) has a cylinder head (1a) coupled to a mounting front side (1c) of a cylinder block (1b). A pump (2a) for conveying the coolant, a heat exchanger and a deaeration tank (2b) are provided for the formation of a cooling circuit (2). An exhaust gas turbocharger (3) is provided, with which a compressor and a turbine are arranged on a shaft. A connecting line (5) is provided into the deaeration tank, which has a gas volume adjacent to a volume at liquid coolant (2e).

Description

• mindestens einem Zylinderkopf, der an einer Montage-Stirnseite mit einem Zylinderblock verbindbar ist, wobei zur Ausbildung eines Kühlkreislaufs eine Pumpe zur Förderung des Kühlmittels, ein Wärmetauscher und ein Entlüftungsbehälter vorgesehen sind, und
• mindestens einem Abgasturbolader, bei dem ein Verdichter und eine Turbine auf derselben Welle angeordnet sind, die drehbar in einem flüssigkeitsgekühlten Lagergehäuse gelagert ist, wobei zur Ausbildung der Flüssigkeitskühlung das Lagergehäuse mittels Verbindungsleitung in den Kühlkreislauf der Brennkraftmaschine eingebunden und zwischen der Pumpe und dem Entlüftungsbehälter angeordnet ist.

The invention relates to a charged liquid-cooled internal combustion engine with

• at least one cylinder head, which is connectable to a cylinder block at a mounting end face, wherein for forming a cooling circuit, a pump for conveying the coolant, a heat exchanger and a vent tank are provided, and
• at least one exhaust gas turbocharger in which a compressor and a turbine are arranged on the same shaft which is rotatably mounted in a liquid-cooled bearing housing, wherein the bearing housing is integrated by means of connecting line in the cooling circuit of the internal combustion engine and arranged between the pump and the venting container to form the liquid cooling ,

In the context of the present invention, the term internal combustion engine includes diesel engines, gasoline engines, but also hybrid internal combustion engines.

To form the individual cylinders of the internal combustion engine, the at least one cylinder head is connected to a mounting end face with a cylinder block. The cylinder block, which at least forms the crankcase, has a corresponding number of cylinder bores for receiving the pistons or the cylinder tubes. The pistons are guided axially movably in the cylinder tubes and, together with the cylinder tubes and the cylinder head, form the combustion chambers of the internal combustion engine.

In the prior art, internal combustion engines are being charged increasingly frequently, the charging being primarily a method of increasing the efficiency by which the air required for the engine combustion process is compressed.

As a rule, an exhaust gas turbocharger is used for the supercharging, in which a compressor and a turbine are arranged on the same shaft, wherein the hot exhaust gas stream is supplied to the turbine, relaxes under energy release in this turbine and the shaft mounted in a bearing housing rotates , The exhaust gas flow to the Turbine and finally delivered to the shaft energy is used to drive the also arranged on the shaft compressor. The compressor conveys and compresses the charge air supplied to it, whereby a charging of the cylinder is achieved.

The advantage of the exhaust gas turbocharger, for example compared to a mechanical supercharger, is that no mechanical connection is required for the power transmission between the supercharger and the internal combustion engine. While a mechanical supercharger obtains the energy required for its drive completely 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.

Charged internal combustion engines are often equipped with a charge air cooling, with which the compressed combustion 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.

The charge 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. At the same vehicle boundary conditions, the load collective can thus be shifted to higher loads, in which the specific fuel consumption is lower. The latter is also referred to as downsizing.

The interpretation of the turbocharger turbocharger is difficult, with basically a noticeable increase in performance in all speed ranges is sought. In the prior art, a strong torque drop is often observed when falling below a certain speed. The torque characteristic of a supercharged internal combustion engine is attempted to be improved by different measures according to the prior art, for example by a small design of the turbine cross-section and simultaneous Abgasabblasung. If the exhaust gas mass flow exceeds a critical size, part of the exhaust gas flow is conducted past the so-called waste gate turbine by means of a bypass line as part of the exhaust gas blow-off. However, this approach has disadvantages at higher speeds.

The torque characteristic of a supercharged internal combustion engine can also be improved by providing a plurality of superchargers - exhaust gas turbochargers and / or mechanical superchargers - arranged in parallel and / or in series in the exhaust gas removal system.

An internal combustion engine with at least one exhaust gas turbocharger is also an object of the present invention.

A supercharged internal combustion engine is thermally loaded higher than a conventional naturally aspirated engine due to the increased mean pressure and therefore also places increased demands on the cooling. In order to keep the thermal load within limits, a supercharged internal combustion engine is usually equipped with a cooling, which is also referred to below as engine cooling. In principle, it is possible to carry out the cooling in the form of air cooling or liquid cooling. Since much larger amounts of heat can be dissipated with liquid cooling, an internal combustion engine of the present type is generally designed with liquid cooling. The internal combustion engine according to the invention is a liquid-cooled internal combustion engine.

The liquid cooling requires the equipment of the internal combustion engine, ie the at least one cylinder head or the cylinder block with a coolant jacket, ie the arrangement of coolant through the cylinder head or block leading coolant channels, which in turn requires a complex structure. In this case, the mechanically and thermally highly stressed cylinder head or block is weakened by the introduction of the coolant channels on the one hand in its strength. On the other hand, the heat must not be directed to the surface as in the air cooling, in order to be able to be dissipated. The heat is already in the interior of the cylinder head or block to the coolant, usually mixed with additives added water. The coolant is thereby conveyed by means of a pump arranged in the cooling circuit, which is usually driven mechanically by means of traction drive, so that it circulates. The heat given off to the coolant is removed in this way from the interior of the cylinder head or block and removed from the coolant in a heat exchanger again. A provided in the cooling circuit vent tank is used to vent the coolant or circuit.

The turbine of the at least one exhaust gas turbocharger is also - as the internal combustion engine itself - thermally highly loaded. As a result, the turbine housing according to the prior art is made of temperature-resistant, frequently nickel-containing material or has to be equipped with liquid cooling in order to be able to use less temperature-resistant materials. The EP 1 384 857 A2 and the German Offenlegungsschrift DE 10 2008 011 257 A1 describe liquid-cooled turbines or turbine housings.

The hot exhaust gas of the supercharged internal combustion engine also leads to a high thermal load of the bearing housing and consequently the bearing of the supercharger shaft. This is a correspondingly high heat input in the bearing for lubrication oil supplied connected. Due to the high speed of the loader shaft, the bearing is usually not designed as a rolling bearing but as a slide bearing. Due to the relative movement between the shaft and the bearing housing, a viable hydrodynamic lubricant film is formed between the shaft and the bearing bore.

The oil should not exceed a maximum allowable temperature, since the viscosity decreases with increasing temperature and the friction behavior deteriorates when a certain temperature is exceeded. Too high an oil temperature also accelerates the aging of the oil, which also worsens the lubricating properties of the oil. Both shorten the maintenance intervals for the oil change and can endanger the proper functioning of the bearing, even irreversible destruction of the bearing and thus of the turbocharger is possible.

For the reasons mentioned above, the bearing housing of a turbocharger of an internal combustion engine of the present type according to the prior art is equipped with a liquid cooling. It is to be distinguished between the liquid cooling of the bearing housing and the above-mentioned liquid cooling of the turbine housing. Nonetheless, both liquid coolers may be in communication with each other, possibly only intermittently; H. communicate with each other.

In contrast to the engine cooling or cooling of the turbine housing, the cooling of the bearing housing must also when the vehicle is parked, ie switched off internal combustion engine, be maintained at least for a certain period after switching off the internal combustion engine to avoid irreversible damage due to thermal overload safely.

This can be accomplished in principle by an additional, electrically operated pump, which is supplied for example by the on-board battery, promotes coolant via connecting line through the bearing housing when the engine is switched off and thus ensures cooling of the bearing housing and the bearing even when the internal combustion engine is out of operation. However, the provision of an additional pump is a relatively expensive measure.

From the prior art, concepts are also known which do without an additional pump. In this case, the connecting line, which leads starting from the cooling circuit of the engine cooling through the bearing housing of the exhaust gas turbocharger to the vent tank, designed at least upstream of the bearing housing as a riser. The promotion of the coolant when the internal combustion engine is switched off by the so-called thermosiphon effect, which is based essentially on two mechanisms.

Due to the - even with the internal combustion engine - continued heat input from the heated bearing housing in the coolant located in the connecting line, the temperature of the coolant increases, whereby the density of the coolant decreases and the volume consumed by the coolant increases. Overheating of the coolant may also result in partial vaporization of coolant, so that coolant passes into the gas phase. In both cases, the refrigerant expands and occupies a larger volume, eventually displacing further refrigerant toward the vent vessel, i. H. is promoted. Due to the self-adjusting vacuum coolant is tracked.

The use of the thermosiphon effect for cooling the bearing housing with the internal combustion engine is often causing problems in practice. Due to the limited space in the engine compartment of a vehicle, it is often not possible to form the connecting line upstream of the bearing housing as a riser or to realize the required difference for the thermosiphon effect in the geodetic height between the bearing housing and vent. The reasons are the following.

When using an exhaust gas turbocharger, efforts are always made, the turbine of the at least one supercharger as close to the outlet of the internal combustion engine, d. H. To arrange the outlet openings of the cylinder to optimally use in this way the enthalpy of the hot exhaust gases, which is largely determined by the exhaust pressure and the exhaust gas temperature and to ensure a fast response of the turbocharger. For these reasons, the turbine of the at least one exhaust gas turbocharger is usually arranged directly on the cylinder head and thus in a position having a comparatively large geodesic height, d. H. starting from an internal combustion engine in the installed position with respect to the other components and units is high.

This installation position of the turbine or the bearing housing makes it difficult to form the connecting line upstream of the bearing housing as a riser, in which the geodesic height continuously increases. Because the vent tank can not be arranged arbitrarily high above the bearing housing. In particular, the components and units installed in the engine compartment must, for reasons of safety, d. H. due to requirements on the crash behavior of the vehicle, maintain a minimum distance to the engine hood. Compliance with a prescribed safety distance to the hood inevitably leads to only a slight difference in height between the bearing housing and vent tank, the lack of height difference or in individual cases to a negative height difference, in which the bearing housing compared to the vent tank has the greater geodetic height.

The circumstances described above make it difficult to promote the coolant by utilizing the thermosiphon effect considerably. An unfavorable installation position of the venting container increases the resistance against which the coolant must be conveyed starting from the bearing housing. A longer residence time in the bearing housing is the result, the coolant can overheat and the pressure - even in the connecting line upstream of the bearing housing - can rise sharply.

As a result, even superheated refrigerant vapor of higher pressure, in particular coolant vapor, passes via connecting line into the venting container. On the one hand, this can lead to a thermal overload, damage or destruction of the usually made of plastic container. For another, the increased Tank pressure cause a pressure relief valve disposed on the container opens uncontrollably and releases vapor refrigerant into the environment. This can cause unwanted noise, especially whistling. In general, the container is equipped with a lid which closes a container opening, which serves for the filling of coolant, and often also receives the pressure relief valve. The highly superheated coolant can also attack the lid or the lid seal and lead to a sticking of the lid.

The pressure and temperature conditions described above can lead to a pulsating coolant delivery, in which the coolant is introduced in beats via connection line in the vent tank. This leads to a foaming or enrichment of the coolant with air. The actual purpose of the vent tank, namely to degas the coolant, d. H. to vent these effects are counteracted.

Against the background of the above, it is the object of the present invention to provide a supercharged liquid-cooled internal combustion engine according to the preamble of claim 1, wherein the cooling of the bearing housing with respect to said requirements, in particular with regard to the thermal load of the venting container is optimized.

• mindestens einem Zylinderkopf, der an einer Montage-Stirnseite mit einem Zylinderblock verbindbar ist, wobei zur Ausbildung eines Kühlkreislaufs eine Pumpe zur Förderung des Kühlmittels, ein Wärmetauscher und ein Entlüftungsbehälter vorgesehen sind, und
• mindestens einem Abgasturbolader, bei dem ein Verdichter und eine Turbine auf derselben Welle angeordnet sind, die drehbar in einem flüssigkeitsgekühlten Lagergehäuse gelagert ist, wobei zur Ausbildung der Flüssigkeitskühlung das Lagergehäuse mittels Verbindungsleitung in den Kühlkreislauf der Brennkraftmaschine eingebunden und zwischen der Pumpe und dem Entlüftungsbehälter angeordnet ist,

die dadurch gekennzeichnet ist, dass

• die Verbindungsleitung in den Entlüftungsbehälter, der neben einem Volumen an flüssigem Kühlmittel auch ein Gasvolumen umfaßt, an einer Stelle einmündet, die mit flüssigem Kühlmittel beaufschlagt ist.

This object is achieved by a charged liquid-cooled internal combustion engine with

• at least one cylinder head, which is connectable to a cylinder block at a mounting end face, wherein for forming a cooling circuit, a pump for conveying the coolant, a heat exchanger and a vent tank are provided, and
• at least one exhaust gas turbocharger in which a compressor and a turbine are arranged on the same shaft which is rotatably mounted in a liquid-cooled bearing housing, wherein the bearing housing is integrated by means of connecting line in the cooling circuit of the internal combustion engine and arranged between the pump and the venting container to form the liquid cooling .

which is characterized in that

• the connecting line into the venting container, which in addition to a volume of liquid coolant also comprises a gas volume, opens at a point which is acted upon by liquid coolant.

According to the invention opens the connection line below the surface level of the liquid coolant in the venting container, d. H. coming from the bearing housing, greatly overheated and optionally gaseous coolant is promoted by utilizing the thermosyphon effect in the located in the venting container volume of liquid coolant inside.

While an introduction of the superheated coolant above the coolant level directly thermally stress the inner wall of the vent tank, would possibly damage, is carried out when feeding the superheated refrigerant below the surface mirror direct mixing with the liquid, already in the container coolant, wherein the mixing temperature setting itself clearly is below the temperature of the superheated refrigerant. Consequently, the thermal load of the container by the proposed measure according to the invention, namely to let open the connecting line below the surface level in the coolant liquid of the venting container, significantly reduced.

The internal combustion engine according to the invention thus solves the problem underlying the invention, namely to provide a charged liquid-cooled internal combustion engine, wherein the cooling of the bearing housing is optimized in particular with regard to the thermal load of the venting container.

The introduction of the superheated coolant via the connecting line into the liquid coolant of the venting container also dampens a pulsating coolant delivery, in which the coolant coming from the bearing housing is intermittently introduced into the venting container. In this respect, a pronounced foaming or accumulation of the coolant with air during the introduction is avoided.

Not only the tank temperature is lowered by the inventive introduction of the coolant below the surface level. The container pressure is reduced, so that no accidental opening of an overpressure valve provided on the container can be observed. An undesirable noise, such as whistling, is thereby avoided.

Since the coolant liquid in the container is not a solid body but rather movable, the position of the surface mirror depends on the installation position or instantaneous position of the container. In order to ensure a fixed, unique reference point, reference is made to a vehicle parked at ground level with the internal combustion engine in the installed position, i. H. with the breather in the installed position.

• jeder Zylinder mindestens eine Auslaßöffnung zum Abführen der Abgase aus dem Zylinder aufweist und sich an jede Auslaßöffnung eine Abgasleitung anschließt, wobei die Abgasleitungen von mindestens zwei Zylindern unter Ausbildung mindestens eines integrierten Abgaskrümmers innerhalb des Zylinderkopfes zu mindestens einer Gesamtabgasleitung zusammenführen, welche in die Turbine des mindestens einen Abgasturboladers mündet.

In internal combustion engines having at least two cylinders, embodiments are advantageous in which

• each cylinder has at least one outlet opening for discharging the exhaust gases from the cylinder and connects to each outlet opening an exhaust pipe, wherein the exhaust pipes of at least two cylinders merge to form at least one integrated exhaust manifold within the cylinder head to at least one total exhaust pipe, which in the turbine of at least an exhaust gas turbocharger opens.

In internal combustion engines with exhaust gas turbocharging - as already stated - sought to arrange the at least one turbine as close to the outlet of the cylinder. The goal is to merge the exhaust pipes according to the embodiment in question while forming at least one integrated exhaust manifold within the cylinder head. The length of the exhaust pipes is thereby reduced. The piping volume, ie the exhaust gas volume of the exhaust pipes upstream of the turbine, is reduced so that the response of the turbine improves. The shortened exhaust pipes also result in lower thermal inertia of the exhaust system upstream of the turbine, so that the temperature of the exhaust gases at the turbine inlet increases, which is why the enthalpy of the exhaust gases at the inlet of the turbine is higher. The merging of the exhaust pipes within the cylinder head also allows a dense packaging of the drive unit. Furthermore, the path of the hot exhaust gases to the various exhaust aftertreatment systems is shortened and the exhaust gases are given little time to cool down, whereby the exhaust aftertreatment systems quickly reach their operating temperature or light-off temperature, in particular after a cold start of the internal combustion engine.

• mindestens drei Zylinder in der Art konfiguriert sind, dass sie zwei Gruppen mit jeweils mindestens einem Zylinder bilden, und
• die Abgasleitungen der Zylinder jeder Zylindergruppe unter Ausbildung eines Abgaskrümmers jeweils zu einer Gesamtabgasleitung zusammenführen.

In internal combustion engines having three or more cylinders, embodiments are also advantageous in which

• at least three cylinders are configured to form two groups each having at least one cylinder, and
• the exhaust gas lines of the cylinder of each cylinder group merge to form an exhaust manifold to form an overall exhaust gas line.

This embodiment is particularly suitable for the use of a twin-flow turbine. A double-flow turbine has an inlet region with two inlet channels, wherein the two total exhaust gas lines are connected to the twin-flow turbine in such a way that in each case an entire exhaust gas line opens into an inlet channel. The merging of the two exhaust gas flows guided in the total exhaust gas lines is optionally carried out downstream of the turbine. However, the grouping of the cylinders or exhaust pipes also offers advantages when using multiple turbines or exhaust gas turbocharger, wherein in each case an overall exhaust gas line is connected to a turbine.

Further advantageous embodiments of the charged liquid-cooled internal combustion engine will be discussed in connection with the subclaims.

Embodiments of the internal combustion engine in which the inlet opening of the connecting line into the venting container has a greater geodetic height than the outlet opening of the bearing housing, to which the connecting line connects, are advantageous in the installation position of the internal combustion engine.

A positive height difference between the bearing housing and venting container, wherein the inlet opening of the venting container with respect to the outlet opening of the bearing housing has the greater geodetic height, supports the promotion of the coolant by means of thermosiphon effect.

Particularly advantageous embodiments of the internal combustion engine, in which the connecting line is designed as a riser. To use or improve the thermosiphon effect, it is advantageous to connect the connecting line at least upstream of the Form bearing housing as a riser, in which the geodesic height increases continuously.

Nevertheless, embodiments of the internal combustion engine may be advantageous in which in the installation position of the internal combustion engine, the inlet opening of the connecting line in the venting container has a lower geodetic height than the outlet opening of the bearing housing, followed by the connecting line.

Requirements for the packaging in the engine compartment and / or compliance with a sufficiently large safety distance to the hood, such a positioning of the venting container may be required, d. H. justify.

Embodiments of the internal combustion engine in which a cooler is provided in the connecting line between the pump and the bearing housing are advantageous.

The radiator lowers the coolant temperature before entering the bearing housing and thus contributes to an increase in the residence time, which is required to overheat the coolant in the bearing housing by heat input.

Benefits arise in particular when the internal combustion engine is switched off, when the engine cooling is out of operation and therefore the bearing housing should be cooled by other measures or mechanisms for a short time on, in order to avoid thermal overheating.

Embodiments of the internal combustion engine in which the cooler is a cooler operating on the principle of air cooling are advantageous.

As already stated in connection with engine cooling, cooling can basically be carried out as air cooling or as liquid cooling. Since comparatively small amounts of heat have to be dissipated when cooling the bearing housing, it is less expensive and sufficient to provide an air cooler upstream of the bearing housing.

The use of an air cooler has other advantages. Cooling systems for modern motor vehicle drives such as the engine cooling of the internal combustion engine according to the invention are preferably equipped with powerful electrically powered fan motors that drive a fan and set in rotation to the heat exchangers of the cooling system even at a standstill, d. H. provide a sufficiently high air mass flow when the vehicle is stationary, or at low vehicle speeds. Frequently, the fan is located in the immediate vicinity and spaced from the heat exchanger in the front-end area of the vehicle.

An air cooler provided upstream of the bearing housing may be arranged in the engine compartment in such a manner that the air flow passed through the fan flows around the air cooler and contributes to the heat dissipation at the surface due to convection. This has advantages in particular after switching off the internal combustion engine when the fan is electrically operated for a short time and the maintenance of the cooling in terms of overheating of the coolant in the bearing housing is particularly useful and necessary.

For the above-mentioned reasons, embodiments of the internal combustion engine are advantageous in which the radiator is arranged between the cylinder block and the heat exchanger of the cooling circuit.

Advantageous embodiments of the internal combustion engine, in which in the connecting line between the pump and the vent container, a throttle element is arranged, which serves to limit the coolant flow rate. The coolant throughput through the vent tank should be as low as possible, as will be explained below.

Embodiments of the internal combustion engine in which the throttle element is arranged downstream of the bearing housing in the connecting line are advantageous.

However, in particular embodiments of the internal combustion engine in which the throttle element upstream of the bearing housing in the connecting line is arranged, since upstream of the bearing housing liquid coolant passes through the throttle element and is throttled, whereas downstream of the bearing housing superheated and optionally vaporous coolant is present and a throttling the promotion of Coolant under Exploitation of the thermosyphon effect may adversely affect, in particular, could promote a pulsating promotion.

Also advantageous are embodiments of the internal combustion engine, in which in the connecting line between the pump and the venting container a depending on the coolant temperature automatically controlling valve is arranged, which serves to control the coolant flow rate.

The valve serves to prevent or minimize the coolant delivery through the bearing housing at low coolant temperatures, in particular after a cold start of the internal combustion engine and during the warm-up phase.

A cooling or coolant delivery at low coolant temperatures is basically not wanted, since this precludes a rapid heating of the internal combustion engine and their aggregates.

In addition, the coolant flow through the vent should be as low as possible, especially at low coolant temperatures. First, the vent requires a certain residence time of the coolant in the vent tank, which is why the throughput is to be limited in principle. On the other hand leads to a low temperature of the coolant or due to the low temperature higher viscosity of the coolant to the fact that the coolant when flowing out of the vent tank - contrary to the actual objective - is enriched with air again.

The self-controlling valve, which may also be referred to as a thermostatic valve, varies depending on the coolant temperature, the flow cross-section of the connecting line and thus controls the coolant flow through the bearing housing in such a way that the throughput is increased with increasing coolant temperature. Consequently, not only the unwanted coolant delivery is counteracted at low coolant temperatures in the present embodiment, but also the coolant delivery and thus the cooling towards high temperatures by increasing the throughput, ie by opening the valve, forced, ie increased. This results in a need-based supply of the bearing housing with coolant, wherein the promotion of the coolant is still based on the thermosiphon effect.

Advantageous embodiments of the internal combustion engine, in which the valve is arranged upstream of the bearing housing in the connecting line.

Advantageous embodiments of the internal combustion engine, in which the valve is arranged downstream of the bearing housing in the connecting line.

In contrast to the above embodiment, the thermostat valve is acted upon in the present case with heated coolant in the bearing housing. This is advantageous because the valve can react almost instantaneously to the temperature of the coolant in the bearing housing and thus turns off in the control of the coolant flow rate directly on the current heat balance in the bearing housing.

In a valve disposed upstream of the bearing housing inevitably results in a time delay, which is due to the fact that the coolant located between the valve and bearing housing in the connecting line must first be heated by heat conduction before the valve can respond to the temperatures present in the housing by opening ,

Nevertheless, as already mentioned, embodiments in which the valve is arranged upstream of the bearing housing in the connecting line are also advantageous.

The valve can also be integrated directly into the bearing housing, allowing a delay-free response to the temperatures in the bearing housing. In addition, parts of the valve, for example the valve housing, can be formed by the bearing housing and the cooling of the bearing housing can be used to cool the valve. This results in further advantages, in particular a compact design and weight savings. The valve can also be integrated into the internal combustion engine, whereby the advantages mentioned above can be realized in an analogous manner.

The valve can be infinitely adjustable or two-stage switchable. A continuously variable valve allows demand-based supply of the bearing housing with coolant in all operating conditions.

The valve may have a leakage current in the closed position. Although this leakage current prevents complete closure of the connecting line at low temperatures, which is why the coolant delivery can not be completely prevented. Nevertheless, some leakage, d. H. Leakage, the valve advantageous to ensure that the valve disposed in the thermocouple, which ultimately initiates the opening process, is constantly acted upon by coolant.

Embodiments of the internal combustion engine in which the connecting line leads through the cylinder block are advantageous.

In the installed position, the cylinder block is usually arranged deep in the engine compartment, d. H. on a low geodetic height compared to the turbine. If the connecting line then leads through the cylinder block upstream of the turbine, this is advantageous in particular with regard to the utilization of the thermosiphon effect and the formation of the connecting line as a riser line. In this configuration, the turbine and the bearing housing to be cooled are arranged geodetically higher than the cylinder block.

But can also be advantageous embodiments of the internal combustion engine, in which the connecting line leads through the cylinder head.

In internal combustion engines, in which the turbine is arranged above the cylinder block, on the cylinder head side facing the mounting end face, the connecting line can also lead starting from the cylinder head to the bearing housing of the turbine, without it would be necessary to form the line as a riser.

The at least one turbine can be designed as a radial turbine, ie, the flow of the blades takes place substantially radially. In this case, essentially radial means that the velocity component in the radial direction is greater than the axial velocity component. The velocity vector of the flow intersects the shaft of the turbine at a right angle if the flow is exactly radial. In order to be able to flow radially to the rotor blades, the inlet region for supplying the exhaust gas is frequently designed as a spiral or worm casing extending all around, so that the inflow of the exhaust gas to the turbine takes place essentially radially. However, the at least one turbine can also be designed as an axial turbine, in which the velocity component in the axial direction is greater than the velocity component in the radial direction.

The at least one turbine can be equipped with a variable turbine geometry, which allows a further adaptation to the respective operating point of an internal combustion engine by adjusting the turbine geometry or the effective turbine cross section. In this case, adjustable guide vanes for influencing the flow direction are arranged in the inlet region of the turbine. Unlike the vanes of the rotating impeller, the vanes do not rotate with the shaft of the turbine.

If the turbine has a fixed invariable geometry, the vanes are not only stationary, but also completely immovable in the entry area, i. H. rigidly fixed. With a variable geometry, however, the guide vanes are indeed arranged stationary, but not completely immobile, but rotatable about its axis, so that the flow of the blades can be influenced.

In principle, a plurality of turbochargers whose turbines or compressors are arranged in series or in parallel can also be used to improve the torque characteristic of the internal combustion engine.

Fig. 1

schematisch in der Seitenansicht eine erste Ausführungsform der aufgeladenen flüssigkeitsgekühlten Brennkraftmaschine.

In the following the invention is based on an embodiment according to FIG. 1 explained in more detail. Hereby shows:

Fig. 1

schematically in side view a first embodiment of the charged liquid-cooled internal combustion engine.

FIG. 1 schematically shows a side view of a first embodiment of the supercharged liquid-cooled internal combustion engine. 1

The internal combustion engine 1 comprises a cylinder head 1a, which is connected to a cylinder block 1b at a mounting end face 1c.

To form the engine cooling 2, a pump 2a is provided, with which coolant is conveyed through a cooling circuit 2. The pump 2a is connected via connecting line 5 with a venting container 2b, from which the degassed coolant is returned to the cooling circuit 2 by being fed into the cooling circuit 2 upstream of the pump 2a.

The internal combustion engine 1 is charged by means of exhaust gas turbocharger 3, which comprises a compressor and a turbine, which are arranged on a common shaft. The shaft is rotatably supported in a liquid-cooled bearing housing 4.

To form the cooling, the bearing housing 4 is integrated by means of connecting line 5 in the cooling circuit 2 of the internal combustion engine 1 and arranged between the pump 2 a and the breather 2 b. The cylinder block 1b serves as a removal point 7 for the coolant and is equipped with a connection for the connecting line 5.

Upstream of the bearing housing 4, a tubular air cooler 6 is arranged in the connecting line 5, which lowers the temperature of the coolant before entering the bearing housing 4.

At the in FIG. 1 illustrated embodiment, the inlet opening 2d of the connecting line 5 in the breather 2b a slightly larger geodetic height than the outlet opening 4a of the bearing housing 4, to which the connecting line 5 connects. The positive height difference between the bearing housing 4 and the breather 2b supports the thermosiphon effect, even if the connecting line 5 upstream of the bearing housing 4 is not formed here as a riser with continuously increasing geodetic height.

The connecting line 5 opens below the coolant level 2c in the breather 2b. In this way, the superheated and possibly gaseous coolant coming from the bearing housing 4 is conveyed into the volume of liquid coolant 2e present in the deaeration vessel 2b.

The feeding of the superheated coolant below the liquid level 2c brings a direct mixing with the liquid, already in the container 2b coolant with it, whereby the thermal load of the container 2b is significantly reduced.

The container 2b is provided with a lid 2f, which closes a container opening, which serves to fill the container 2b with coolant, and also accommodates a pressure relief valve (not shown).

reference numeral

1

Internal combustion engine

1a

cylinder head

1b

cylinder block

1c

Mounting-end side

2

Cooling circuit, engine cooling

2a

pump

2 B

bleed tank

2c

Liquid level, coolant level

2d

Mouth, inlet opening in the deaeration tank

2e

Volume of liquid coolant

2f

cover

3

turbocharger

4

bearing housing

4a

Outlet opening from the bearing housing

5

connecting line

6

cooler

7

Connection, extraction point

Claims (15)

Charged liquid-cooled internal combustion engine (1) with at least one cylinder head (1a) which can be connected to a cylinder block (1b) on a mounting end face (1c), a pump (2a) for conveying the coolant, a heat exchanger and a deaeration tank (2) being formed to form a cooling circuit (2) 2b) are provided, and - At least one exhaust gas turbocharger (3) in which a compressor and a turbine are arranged on the same shaft which is rotatably mounted in a liquid-cooled bearing housing (4), wherein for forming the liquid cooling the bearing housing (4) by means of connecting line (5) in the Cooling circuit (2) of the internal combustion engine (1) is integrated and arranged between the pump (2a) and the venting container (2b),
characterized in that - The connecting line (5) in the venting container (2b), which in addition to a volume of liquid coolant (2e) also comprises a gas volume, at a point (2d) opens, which is acted upon by liquid coolant. Charged liquid-cooled internal combustion engine (1) according to claim 1, characterized in that - in the installation position of the internal combustion engine (1) - the inlet opening (2d) of the connecting line (5) in the vent tank (2b) has a greater geodetic height than the outlet opening (4a ) of the bearing housing (4) to which connects the connecting line (5). Charged liquid-cooled internal combustion engine (1) according to claim 1 or 2, characterized in that the connecting line (5) is designed as a riser. Charged liquid-cooled internal combustion engine (1) according to claim 1, characterized in that - in the installation position of the internal combustion engine (1) - the Inlet opening (2d) of the connecting line (5) in the venting container (2b) has a lower geodetic height than the outlet opening (4a) of the bearing housing (4), to which connects the connecting line (5). Charged liquid-cooled internal combustion engine (1) according to one of the preceding claims, characterized in that in the connecting line (5) between the pump (2a) and the bearing housing (4), a cooler (6) is provided. Charged liquid-cooled internal combustion engine (1) according to claim 5, characterized in that the cooler (6) is a working on the principle of air cooling radiator. Charged liquid-cooled internal combustion engine (1) according to claim 5 or 6, characterized in that the cooler (6) between the cylinder block (1b) and the heat exchanger of the cooling circuit (2) is arranged. Charged liquid-cooled internal combustion engine (1) according to one of the preceding claims, characterized in that in the connecting line (5) between the pump (2a) and the venting container (2b), a throttle element is arranged, which serves to limit the coolant flow rate. Charged liquid-cooled internal combustion engine (1) according to claim 8, characterized in that the throttle element is arranged downstream of the bearing housing (4) in the connecting line (5). Charged liquid-cooled internal combustion engine (1) according to claim 8, characterized in that the throttle element upstream of the bearing housing (4) in the connecting line (5) is arranged. Charged liquid-cooled internal combustion engine (1) according to one of the preceding claims, characterized in that in the connecting line (5) between the pump (2a) and the venting container (2b) is arranged depending on the coolant temperature automatically controlling valve, which is the control of Coolant flow rate is used. Charged liquid-cooled internal combustion engine (1) according to claim 11, characterized in that the valve upstream of the bearing housing (4) in the connecting line (5) is arranged. Charged liquid-cooled internal combustion engine (1) according to claim 11, characterized in that the valve downstream of the bearing housing (4) in the connecting line (5) is arranged. Charged liquid-cooled internal combustion engine (1) according to one of the preceding claims, characterized in that the connecting line (5) through the cylinder block (1b) leads. Charged liquid-cooled internal combustion engine (1) according to one of the preceding claims, characterized in that the connecting line (5) through the cylinder head (1 a) leads.

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