EP2297434B1 - Device and method for ventilating a crankcase - Google Patents

Abstract

The invention relates to a device and a method for ventilating a crankcase (10) of a supercharged internal combustion engine, wherein a plurality of collecting chambers (28, 30) for ventilation gases are provided, having individual oil separators (88, 90) associated therewith. Contrary to full load operation, during partial load operation the ventilation gas of a collecting chamber (28) is fed to a non-associated oil separator (90) and is ventilated using the same.

Description

The invention relates to a device and a method for crankcase ventilation and recycling of the vent gases in the combustion chamber of a supercharged internal combustion engine according to the preambles of claims 1 and 17 respectively.

In the operation of internal combustion engines, in particular reciprocating engines, combustion gases between the cylinders and the piston rings can escape into the crankcase. These gases are referred to as blow-by gases and can build up considerable pressures within the crankcase, so that a venting of the crankcase is required The blow-by gases in the crankcase are loaded with engine oil, so they must not be discharged into the environment and usually pass through an oil separator to finally be passed into the intake of the engine. From here, the gases are returned to the combustion chambers of the cylinders.

In order to control the pressure in the crankcase as constant as possible, pressure control valves or even variable throttles with or without a check function, e.g. so-called PCV valves (positive crankcase ventilation) be provided. About such tax Ventite the negative pressure in the intake tract is used to suck gases from the crank chamber. When a turbocharger is provided, at partial load operation, the exhausted gas is drawn into the intake stroke downstream of the turbocharger and into the intake tract at full load upstream of the turbocharger. Check valves must prevent at full load that the pressure on the so-called. Part-load ventilation services is transmitted to the crankcase.

The extraction of the gases takes place either in the region of the bottom of the crankcase above the oil level or in the region of the cylinder head. In the case of extraction in the region of the cylinder head, a distinction is made in particular between the arrangement of the collection chamber in the cylinder head itself or in a valve cover surrounding the cylinder head. Incidentally, the collecting chambers are the spaces in which the venting gas is located in front of the extraction system.

From the EP 1 310 639 A1 is a crankcase ventilation in a V-engine known. Each cylinder bank is associated with a turbocharger, with a common intake manifold is provided for both rows. In addition, there is a common oil separator for both rows of cylinders, wherein the provided in the cylinder head cover collecting chambers are coupled together via a Verbindurigsleitung. The gas is then introduced in partial load operation downstream of the throttle cap in the intake and at full load in an air supply pipe upstream of the turbocharger.

Another variant of a crankcase ventilation of a V-engine provides for each cylinder row its own turbocharger and its own oil separator. For oil separators, especially inertial separators, the degree of separation depends in part on the throughput. There are therefore oil separators in which individual stages (individual cyclones in the case of multiple cyclone separation) can be switched on via switching elements. Such switching elements usually consist of a spring and a, operated by the spring closure element.

The US 2008/0083399 A1 , which forms the closest prior art, describes a method and an apparatus for venting a crankcase of an internal combustion engine, which has a plurality of exhaust gas collecting chambers, which are associated with their own oil separator. Both in full load operation and in partial load operation, the venting gases of the collecting chambers are vented via their own, respectively assigned oil separators.

From the DE 19 918 311 A It is also known to divide the blow-by gas flow through at least one control element into a plurality of partial volume flows and supply each partial flow to an oil separator. At low volume flows, for example at partial load, only one oil separator is applied by a corresponding control, with large volume flows, such as at full load, several oil separators.

The object of the invention is to provide a simpler device for crankcase ventilation and a method for this purpose.

The inventive device for Kurbe.lgehäuseentlüftung and return of the vent gases (called blow-by gases) in the combustion chamber of a supercharged internal combustion engine has a plurality of the crankcase and one or more cylinders associated. Collection chambers for vent gases before. These collection chambers may be provided in the crankcase or cylinder head side. At least one turbocharger is arranged in a suction line, wherein several suction lines may also be provided. In addition, each collecting chamber is assigned at least one separate oil separator. A part throttle return line leads from an oil separator downstream to the turbocharger to the intake line into which it flows. Moreover, from each oil separator, there is provided a full-gas return line for vent gas, which opens into the intake pipe upstream of the turbocharger. In full load operation flows. Venting gas of each collection chamber via the assigned, own oil separator in the suction line. At least in partial load operation, however, the collection chambers are fluidly connected to each other, so that Venting gas is passed from at least two collection chambers via the oil separator of a collection chamber and the partial load return line into the suction line.

The device according to the invention provides that in partial load operation less oil separators are in operation, so that the then operating oil separator achieve a higher throughput and Ölabscheidegrad than in partial load operation. As a result, additional switching elements are unnecessary. Preferably, the device according to the invention thus has no switchable oil separator.

According to the preferred embodiment, a plurality of rows of cylinders are provided, and each row of cylinders has its own collection chamber. As already explained, these collecting chambers can be sections of the crankcase or be assigned to the cylinder heads and lie in their region.

As already explained; the collecting chambers must be connected to each other by flow. This can preferably take place via the common crankcase, so that additional lines could be omitted.

Preferably, a plurality of turbochargers are also provided, each associated with a single or a group of cylinders. According to the preferred embodiment, each row of cylinders (also called a cylinder bank) has its own associated turbocharger.

Preferably, an oil separator is assigned to each turbocharger.

Partial return lines lead from the partially trapped oil separator to the intake manifolds downstream of the plurality of turbochargers. It should be emphasized that, of course, several oil separators can work in part-load operation, but not all of these working oil separators, the gas is then branched back to the intake pipes, also to intake pipes of non-active oil separators.

Full-return lines may be provided which lead from the oil separators to the intake passages of the plurality of turbochargers. These full return lines will then direct the gas to the intake lines upstream of the turbochargers at full load.

According to one embodiment of the invention, one, preferably only one, aerator guide is provided which leads to a collection chamber and over which Connection of the collecting chambers ventilated. Such a ventilation line allows a so-called. Rinsing of the crankcase with fresh air, which inter alia, the chemical aging of the lubricating oil is reduced. In this embodiment, the construction cost of ventilation is very low.

Preferably, the ventilation line in the oil separator, which does not work in partial load, open, so that from this the ventilation takes place. This also reduces the number of connections or parts provided with connections.

In order to reduce the number of lines, the aeration line may be the full return line of the partially non-operating Ölabscheiders this line has a double function so to speak, and is flowed through in two directions, in one direction of the venting gas and in the other direction of the fresh air.

In order to avoid switchable valves and yet to achieve a clear flow guidance in the various load operations, check valves are arranged in the Vottatrückfuhrteitungen. These prevent suction via these lines in partial load operation.

The check valve in the full return line serving as a vent line may be provided with a throttled bypass, which is then vented, although the check valve is actually in the closed position. This embodiment can be realized very inexpensively.

In the at least one or each partial load line should be arranged a throttle unit with non-return function (e.g., PCV valve). When supplying fresh air, such PCV valves prevent the backflow of the gases. Such PCV valves are available in heatable and unheated version. By means of the negative pressure in the intake tract, the venting gases are extracted via the PCV valves, in partial load operation.

The oil separators are inertial separators, in particular cyclone separators, as already mentioned, preferably even non-switchable cyclone separators.

The venting takes place according to the preferred embodiment of the cylinder head side, wherein the Sammelkamern can be provided in the cylinder head or in the valve bonnets.

Of course, in the embodiment with venting via the crankcase itself, the collecting chambers can also be sections of the interior of the crankcase that merge into one another. For optimal venting and ventilation, i. Flushing, it would be advantageous in this context, when the lines open as far away from each other in the crankcase.

The invention further relates, as already explained, a method for venting a crankcase of an internal combustion engine, in particular a reciprocating engine, which has a plurality of collecting chambers for venting gases, which own oil separators are assigned. The method provides that in the partial load mode, the vent gases of a collection chamber is guided to an unassigned oil separator and vented through this, whereas in full load operation, the vent gases of the collecting chambers are vented through their own, each associated oil separator.

Further features and advantages of the invention will become apparent from the following description of a preferred embodiment, which is shown in the single schematic figure.

In the figure, an engine, more specifically a reciprocating engine of an internal combustion engine is shown. The engine is in this embodiment, a V-type engine with a crankcase 10, which has two rows of cylinders 12, 14. Denoted at 16 are the pistons and at 18 the intake and exhaust valves housed in the cylinder heads 20,22. Each row of cylinders is covered with a so-called. Valve cover 24, 26, wherein the valve bonnets 24, 26 can also merge into one another in one piece.

Between the valve covers 24, 26 and the cylinder heads 20, 22 are each so-called. Collection chambers 28, 30 are provided for vent gases.

These vent gases are contaminated with water, oil from the crankcase 10 and other components blow-by gases 32, which can escape between the piston 16 and the cylinders 34, 36 from the corresponding work spaces in the crankcase chamber 38. In the crankcase room 38 these blow-by gases 32 rupture oil 40 at the bottom of the crankcase chamber 38. The resulting vent gas 32 is then in the crankcase chamber 38, where it would generate an overpressure.

The vent gases 32 not only spread in the crankcase chamber 38, but may flow through passages 42, 44 in the cylinders 34, 36 or between the cylinders 34, 36 and the valve bonnets 24, 26 to the cylinder heads 20, 22.

In the illustrated embodiment, a separate collection chamber 28, 30 is provided for the vent gases for each cylinder row 12, 14 between the cylinder heads 22, 24 and the associated valve bonnets 24, 26.

Alternatively, the collection chambers 28, 30 could of course also be formed in the area of the cylinder heads 20, 22 and the cylinder head cover, as described, for example, in US Pat DE 35 09 439 C2 is shown.

The collection chambers 28, 30 are interconnected via the crankcase 10 or, more specifically, via the merging passages 42, 44 (e.g., on the facing sides of the cylinders 34, 36). The connection point is designated 46. In the region of this connection point 46, one of the several outflow openings 48 for the venting gas is also provided. The arrow 50 symbolizes at this point, the venting gas, which flows into the passages 42, 44.

The engine block shown is of course integrated in an air supply and an exhaust system, which will be described in more detail below.

Each cylinder row 12, 14 is associated with its own, divided into several sections intake line 52, 54, in each of which a separate intake silencer 56 and a possibly necessary hot-film air mass meter 58 are integrated. Each intake pipe 52, 54 is also associated with its own turbocharger 60, 62, which is integrated in an exhaust pipe 64, 66 and is driven by the exhaust gas.

The turbochargers 60, 62 divide the intake passages 52, 54 into an upstream section 68, 70 and a downstream section 72, 74.

In the respective downstream portion 72, 74 are each a throttle valve 76, 78 and a charge air cooler 80, 82 integrated.

In the internal combustion engine, a device for crankcase ventilation and return of the venting gases in the respective combustion chamber 84, 86 of the cylinder 34 and 36 is provided.

This device includes, among other things, the collection chambers 28, 30 and at least one of each collection chamber 28, 30 associated, own oil cutter 88, 90th

Preferably, the oil separators 88, 90 are cyclone separators, with no switchable cyclones.

From the oil separator 88, a full return line 92 leads into the upstream section 68 of the intake line 52 for the cylinder bank 12. In the full return line 92, a check valve 94 is integrated, which can be bypassed via a throttle 96 by-pass. Of course, the bypass with throttle 96 may also be fully integrated into the check valve 94.

The oil separator 90 of the other collection chamber 30 has an outgoing from the oil separator 90 gas recirculation line, which is divided several times, namely on the one hand in a Vollastrückführleitung 98, which opens into the upstream portion 70 and in which a check valve 99 is seated, and two partial load return lines 100, 102nd

The partial flow return line 100 is provided with a so-called PCV valve 104 and opens into the downstream section 72 of the suction line 52 which is not actually associated with the oil separator 90.

The partial flow return line 102 is also provided with a PCV valve 106 and opens into the downstream section 74 of the suction line 54 associated with the oil separator 90.

The part throttle return lines 100, 102 preferably end after the throttle valves 76, 78 and also preferably after the intercoolers 80, 82nd

In the following, the operation of the crankcase ventilation device and the procedure behind it are described in more detail.

At full load, the exhaust gases drive the two turbochargers 60, 62, so that in the downstream sections 72, 74, a relatively high pressure prevails. The resulting in the combustion chambers 84, 86 exhaust gases are guided via the exhaust valves 18 to the exhaust pipes 64, 66. Blow-by gases 32, however, reach the crankcase chamber 38, where they also entrain oil 40. The resulting vent gases pass through the outflow openings 48 into the passages 42, 44 and thus into the collection chambers 28, 30 in the region of the cylinder heads 20, 22nd

In the upstream sections 68, 70 there is a vacuum so that the vent gases flow through the oil separators 88, 90 (see arrows in the plenums 28, 30). In the oil separators 88, 90, the retained oil is then returned to the collection chambers 28, 30 where it flows along the walls of the passages 42, 44 back into the crankcase chamber 38 (see bold arrows 108). The vent gas then flows from the oil separators 88, 90 through the open check valves 94, 99 into the upstream sections 68, 70 back into the exhaust conduits 64, 66. At full load, the PCV valves 104, 106 are high in the downstream sections 72, 74 closed.

At partial load, there is a vacuum in the downstream sections 72, 74 so that the PCV valves 104, 106 are open, whereas the valves 94, 99 are closed.

Since the collection chamber 28 does not have its own, open discharge line in partial load operation, the venting gas of the collection chamber 28 flows through the flow connection (here the passages 42, 44) to the collection chamber 30. Thus, a higher amount of vent gas is sucked through the oil separator 90, which can thus work more effectively ,

This switchover between partial and full load takes place for the venting without additional valve devices. The vent gas then splits downstream of the oil separator 90 and passes through the open PCV valves 104, 106 into the downstream sections 72, 74 of the exhaust conduits 64, 66, respectively.

In partial load operation, ventilation also takes place through fresh air, namely ventilation of both the collection chambers 28, 30 and the crankcase space 38. Via the throttle 46 namely sucked fresh air (symbolized by a broken line parallel to Vollastrückführleitung 92) via Vollastrückführleitung 92 in the oil separator 88 and thus into the plenum 28. From there, the fresh air can all provided with the vent gas spaces and chambers flow through and get to the oil separator 90.

The method according to the invention therefore provides that in part-load operation, the venting gases of a collection chamber 28 are led to an unallocated oil separator 90 and vented through it, whereas in full-load operation, the venting gases of the collection chambers 28, 30 are vented via their own respective assigned oil separators 88, 90 ,

In partial load operation, a higher degree of separation in the oil separator 90 and thus an improvement in efficiency is achieved since separators are normally designed for maximum throughput. The oil separator 90 thus receives twice the amount of deaerating gas including aeration gas and works almost continuously only at maximum throughput. It also results in a lower coking of the intake valves. Since no additional switching elements are needed, resulting in lower costs and a lower weight.

Claims (17)

1. A device for venting a crankcase and returning the venting gases to the combustion chamber (84, 86) of a supercharged internal combustion engine, comprising
   a number of collecting chambers (28, 30) for vent gases, associated with the crankcase (10) and with individual cylinders or with a number of cylinders (34, 36),
   at least one turbocharger (60, 62) disposed in an intake manifold (52, 54),
   a number of oil separators (88, 90), wherein each collecting chamber (28, 30) has at least one individual oil separator (88, 90) and
   a part-load return pipe (100, 102) leading from an oil separator (90) to the intake manifold (52, 54) in the downstream direction of the turbocharger (60, 62),
   wherein a full-load return pipe (92, 98) leads from each oil separator (88, 90) to the intake manifold (52, 54) upstream of the turbocharger (60, 62) and
   wherein during full-load operation, venting gases from each collecting chamber (28, 30) flow through the associated oil separators (88, 90) into the intake manifold (52, 54), characterised in that
   at least during part-load operation, the collecting chambers (28, 30) are connected for flow purposes so that venting gases from at least two collecting chambers (28, 30) flow through the oil separators (90) belonging to a collecting chamber (30) into the intake manifold (52, 54) and also flow through the part-load return pipe (100, 102).
2. A device according to claim 1, characterised in that a number of rows of cylinders (12, 14) are provided and each row (12, 14) comprises an individual collecting chamber ((28, 30).
3. A device according to claim 1 or claim 2, characterised in that the collecting chambers (28, 30) are connected to one another for flow purposes via the common crankcase (10).
4. A device according to any of the preceding claims, characterised in that a number of turbochargers (60, 62) are provided, each associated with individual cylinders or a group of cylinders (34, 36).
5. A device according to claim 4, characterised in that each turbocharger (60, 62) is associated with an oil separator (88, 90).
6. A device according to claim 4 or claim 5, characterised in that part-load return pipes (100, 102) lead from the oil separator (90) flowed through during part-load operation to the intake manifolds (52, 54), downstream of the number of turbochargers (60, 62).
7. A device according to any of claims 4 to 6, characterised in that full-load return pipes (92, 98) lead from the oil separators (88, 90) to the intake manifolds (52, 54) of the associated turbochargers (60, 62).
8. A device according to any of the preceding claims, characterised in that a vent pipe is provided, leading to a collecting chamber (28) and vented via the connection between the collecting chambers (28, 30).
9. A device according to claim 8, characterised in that the vent pipe opens into the oil separators (88) which are not operating under partial load.
10. A device according to claim 8 or claim 9, characterised in that the vent pipe is the full-load return pipe (92).
11. A device according to any of the preceding claims, characterised in that non-return valves (94, 99) are provided in the full-load return pipes (92, 98).
12. A device according to claim 10 or claim 11, characterised in that the non-return valve (94) in the full-load return pipe (92) serving as a vent pipe is provided with a throttled bypass.
13. A device according to any of the preceding claims, characterised in that a variable throttle valve, particularly a PCV valve (104, 106) is provided in the at least one or in each part-load return pipe (100, 102).
14. A device according to any of the preceding claims, characterised in that the oil separators (88, 90) are inertial, especially cyclone separators.
15. A device according to any of the preceding claims, characterised in that venting occurs at the cylinder head end.
16. A device according to claim 15, characterised in that the collecting chambers (28, 30) are provided in valve hoods (24, 26).
17. A method of venting a crankcase (10) of an internal combustion engine comprising a number of collecting chambers (28, 30) for vent gases, associated with respective oil separators (88, 90), wherein during full-load operation the venting gases in the collecting chambers (28, 30) are vented via their respective associated oil separators (88, 90),
    characterised in that
    during part-load operation the venting gases in a collecting chamber (28) are conveyed to a non-associated oil separator (90) and vented through it.

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