DE102018114342A1 - Process for venting a crankcase of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for venting a crankcase (2) of an internal combustion engine (1), wherein - in a first operating state in which the internal combustion engine (1) is deactivated, crankcase air containing a condensate of fuel, engine oil and possibly water, by means of a crankcase ventilation device (13) is conveyed out of the crankcase (2), - the engine oil contained in the condensate is separated by means of an oil separator and returned to the crankcase (2) or an oil pan (3) of the internal combustion engine (1), - one after the fuel-air mixture remaining in the oil separation is fed to a regenerable storage means (21) in which the fuel is stored, and - the air contained in the fuel-air mixture is introduced into the internal combustion engine (1).

Description

The present invention relates to a method for venting a crankcase of an internal combustion engine.

An internal combustion engine has a crank mechanism, which is housed in a crankcase. Effective and reliable oil lubrication of its movable parts, in particular its bearing and sliding points, is required for the operation of the internal combustion engine. An oil pan is therefore arranged below the crankcase and thus at the lowest point of the internal combustion engine, in which the engine oil provided for lubrication is kept.

During the operation of the internal combustion engine, condensate can form inside the crankcase and also get into the oil pan of the internal combustion engine. The main component of this condensate is unburned fuel, which can enter the crankcase via the combustion chamber. The condensate also contains water and engine oil components. The condensate can get into the oil pan and there dilute the engine oil intended for the lubrication of the internal combustion engine, so that its lubricity is reduced. This problem arises in particular in the short-distance operation of a motor vehicle equipped with the internal combustion engine, when the internal combustion engine is in a cold operating state below its target operating temperature, in which the condensate cannot be evaporated to a sufficient extent. Furthermore, this problem also occurs in hybrid vehicles which have an electric machine as a further drive device in addition to the internal combustion engine. A constant activation and deactivation of the internal combustion engine also has the consequence that it often works in a cold operating state below its target operating temperature.

From the DE 1 426 130 A , the DE 10 2010 024 172 A1 and the DE 103 35 909 A1 Different measures for crankcase ventilation of an internal combustion engine are known.

The invention has for its object to provide a method for venting a crankcase of an internal combustion engine, by means of which the condensate content in the engine oil can be reduced, so that the lubricity of the engine oil can be improved.

This object is achieved by a method having the features of claim 1. The subclaims relate to advantageous developments of the invention.

• - in einem ersten Betriebszustand, in dem die Brennkraftmaschine deaktiviert ist, Kurbelgehäuseluft, die ein Kondensat aus Kraftstoff, Motoröl und gegebenenfalls Wasser enthält, mittels einer Kurbelgehäuseentlüftungsvorrichtung aus dem Kurbelgehäuse gefördert wird,
• - das in dem Kondensat enthaltene Motoröl mittels eines Ölabscheiders abgeschieden wird und in das Kurbelgehäuse oder eine Ölwanne der Brennkraftmaschine zurückgeführt wird,
• - ein nach der Ölabscheidung verbleibendes Kraftstoff-Luftgemisch einem regenerierbaren Speichermittel zugeführt wird, in dem der Kraftstoff gespeichert wird, und
• - die in dem Kraftstoff-Luft-Gemisch enthaltene Luft in die Brennkraftmaschine eingeleitet wird.

A method according to the invention for venting a crankcase of an internal combustion engine provides that

• in a first operating state, in which the internal combustion engine is deactivated, crankcase air, which contains a condensate of fuel, engine oil and possibly water, is conveyed out of the crankcase by means of a crankcase ventilation device,
• the engine oil contained in the condensate is separated off by means of an oil separator and returned to the crankcase or an oil pan of the internal combustion engine,
• a fuel-air mixture remaining after the oil separation is fed to a regenerable storage medium in which the fuel is stored, and
• - The air contained in the fuel-air mixture is introduced into the internal combustion engine.

The method according to the invention enables the above-described measures for active crankcase ventilation, particularly in the case of a frequent, in particular cycle-like, repetition when the internal combustion engine is deactivated to permanently reduce the condensate in the engine oil within the internal combustion engine.

The engine oil separated by the oil separation and thereby separated from the other constituents of the condensate is returned to the oil pan of the internal combustion engine in the process presented here. In particular, this results in a stable lubricating oil viscosity and thus a better lubricating ability of the engine oil. Furthermore, there is advantageously a reduced chemical load on sealing elements, in particular elastomer sealing elements, which are used to seal the internal combustion engine and can be chemically attacked by the condensate. The air contained in the fuel-air mixture, which is introduced into the internal combustion engine via the storage means, is preferably cleaned by means of the storage means.

In a preferred embodiment it is proposed that the air contained in the fuel-air mixture be introduced into the oil pan of the internal combustion engine. It has been shown that the introduction of the air into the oil pan is more advantageous than, for example, the introduction into the crankcase arranged above the oil pan, since the air can mix better with the condensate.

In a particularly preferred embodiment it is provided that in a second operating state in which the internal combustion engine is activated, the storage means for regeneration Purge air is supplied and thereby a fuel-air mixture is obtained, which is fed to a combustion process of the internal combustion engine. This active purging of the storage medium with purging air, which is preferably made available to the storage medium in the form of ambient air, enables an effective regeneration of the storage medium.

The fuel-air mixture obtained by the regeneration of the storage means can preferably be introduced into a fuel-air mixture inlet line of the internal combustion engine. As a result, the fuel-air mixture can be fed to the combustion process of the internal combustion engine in a simple manner.

In a particularly preferred embodiment, it is proposed that the fuel / air mixture obtained by the regeneration of the storage means, depending on an operating point of the internal combustion engine, upstream or downstream of a throttle device, in particular a throttle valve, arranged in the fuel / air mixture inlet line. is introduced into the fuel-air-mixture inlet line. If a motor vehicle equipped with the internal combustion engine has an exhaust gas turbocharger, the fuel / air mixture can be fed to a compressor of the exhaust gas turbocharger when it is introduced upstream of the throttle device, in particular the throttle valve.

In an advantageous embodiment it can be provided that the supply of purge air is interrupted after the regeneration of the storage medium.

In a particularly advantageous development, there is the possibility that in the second operating state of the internal combustion engine crankcase air is conveyed through the crankcase ventilation device and the fuel-air mixture obtained after the oil separation is introduced into the fuel-air-mixture inlet line. Thus, the amount of condensate in the engine oil can be effectively reduced in an advantageous manner even during the ongoing operation of the internal combustion engine - especially if the internal combustion engine has not yet reached its target operating temperature.

In a preferred embodiment, there is the possibility that the fuel / air mixture obtained after the oil separation, depending on an operating point of the internal combustion engine, upstream or downstream of the throttle device, in particular the throttle valve, arranged in the fuel / air mixture inlet line Air-fuel mixture inlet line is introduced. If the motor vehicle equipped with the internal combustion engine has an exhaust gas turbocharger, the fuel / air mixture can be fed to a compressor of the exhaust gas turbocharger when it is introduced in the direction of flow upstream of the throttle device, in particular the throttle valve.

In a preferred embodiment it can be provided that a crankcase ventilation device with an integrated oil separator is used. This embodiment offers particular advantages in terms of installation space.

In a particularly preferred embodiment, it is proposed that an activated carbon filter is used as the storage means, which is preferably heated during regeneration. The activated carbon filter in particular enables reliable storage of the fuel contained within the fuel-air mixture supplied to it. In addition, the activated carbon filter preferably also ensures effective cleaning of the air that is supplied to the internal combustion engine. Since the activated carbon filter provided as a storage medium cools down when the internal combustion engine is activated due to the fuel / air mixture no longer being supplied to it, it is expedient to heat it actively, in particular by means of an appropriate heating device, for an improved regeneration result.

Further features and advantages of the present invention will become clear from the following description of a preferred exemplary embodiment with reference to the accompanying 1 in which an internal combustion engine 1 is shown in schematically highly simplified form, the a venting arrangement 100 has to carry out a method for venting a crankcase 2 the internal combustion engine 1 is set up.

The internal combustion engine 1 has a crankcase in a manner known per se 2 on, at the bottom and thus at the lowest position of the internal combustion engine 1 an oil pan 3 is arranged. For the operation of the internal combustion engine 1 Effective oil lubrication of moving parts, especially of bearings and sliding points, is required. The engine oil intended for lubrication is inside the oil pan 3 maintained. Inside the crankcase 2 is a crank mechanism 4 provided the one crankshaft 5 with a number of pistons 50 having. In 1 is just a single piston 50 shown within a cylinder 60 of a cylinder head 6 the internal combustion engine 1 is movable in the axial direction.

Furthermore, the internal combustion engine 1 a fuel-air mixture inlet line 7 With an inlet valve means 8th and a throttle valve 9 on. Via this fuel-air-mixture inlet line 7 can be a combustion chamber 10 that is inside the cylinder 6 is formed during the operation of the internal combustion engine 1 a fuel-air mixture can be supplied. The internal combustion engine preferably has 1 at least one exhaust gas turbocharger not explicitly shown here, which is set up to pre-compress the fuel-air mixture with the aid of a compressor. Thus, the fuel-air mixture flows when the intake valve means is open 8th pre-compressed in the combustion chamber 10 one and is inside the combustion chamber 10 by means of the piston 50 further compressed before it is subsequently ignited. In addition, the internal combustion engine 1 an outlet pipe 11 with an outlet valve means 12 on which the during the operation of the internal combustion engine 1 combustion exhaust gases generated by the combustion process can be removed.

During the operation of the internal combustion engine 1 can get inside the crankcase 2 form a condensate. The main constituent of this condensate is unburned fuel that flows through the combustion chamber 10 in the crankcase 2 can reach. The condensate also contains water and engine oil components. If this condensate in the oil pan 3 arrives, this inevitably leads to a thinning of the moving parts of the internal combustion engine for the lubrication 1 provided engine oil. This thinning has the consequence that the lubricity of the engine oil is reduced. This problem arises particularly in the short-distance operation of one with the internal combustion engine 1 equipped motor vehicle when the internal combustion engine 1 is in a cold operating state (ie below its target operating temperature) in which the condensate cannot be evaporated to a sufficient degree. Furthermore, this problem also occurs with hybrid vehicles that are in addition to the internal combustion engine 1 have an electrical machine as a further drive device. A constant activation and deactivation of the internal combustion engine 1 also has the consequence that it often works in a cold operating state below its target operating temperature.

In order to remedy the problem of increased oil dilution due to the condensate and the resulting reduced lubricity of the engine oil, the venting arrangement is 100 for the crankcase 2 the internal combustion engine 1 provided an active ventilation of the crankcase 2 allows. The condensate mixes inside the crankcase 2 with air, so that through the active crankcase ventilation, the condensate-air mixture, which is also referred to below as crankcase air, from the crankcase 2 can be carried out.

The venting arrangement 100 has an active crankcase ventilation device 13 on that to an electric drive means 14 is connected and includes an oil separator, the operation of which will be explained in more detail below. The venting arrangement 100 has a condensate supply line 15 on the crankcase ventilation device 13 with the crankcase 2 is in a flow connection. There is also an oil return line 16 provided to the crankcase ventilation device 13 and the crankcase 2 or alternatively also directly to the oil pan 3 connected. During the vent assembly operation 100 the crankcase ventilation device 13 the condensate-air mixture is supplied, the water contained therein on the flow path to the crankcase ventilation device 13 already largely, preferably completely, is carried out. The crankcase ventilation device oil separator 13 is designed to separate the engine oil contained in the condensate-air mixture. Via the oil return line 16 the separated engine oil is returned to the crankcase 2 returned so that it from there into the oil pan 3 the internal combustion engine 1 can reach. After separating the engine oil, the crankcase ventilation device can be discharged through an outlet 13 a fuel-air mixture from the crankcase ventilation device 13 be carried out.

The venting arrangement 100 also has three switchable valve means 17 . 18 . 19 on. A first valve means 17 is as a two-way valve means with an inlet 170 as well as a first outlet 171 and a second outlet 172 , between which can be switched during operation. The entrance 170 is by means of a connecting line 20 with the crankcase ventilation device outlet 13 connected in terms of flow.

The venting arrangement 100 further comprises a regenerable storage medium 21 with a first entry 210 , a second inlet 211 as well as an outlet 212 , The storage medium 21 In the present case, it is designed as an activated carbon filter and is set up to store the fuel contained in the fuel-air mixture supplied to it and preferably also to purify the air resulting therefrom.

A second valve means 18 , which is also designed as a two-way valve means, has an inlet 180 as well as a first outlet 181 and a second outlet 182 on, between which you can switch. The entrance 180 of second valve means 18 is by means of a connecting line 213 to the outlet 212 of the storage medium 21 connected. At the first outlet 181 of the second valve means 18 is an air outlet pipe 23 connected that in a lower area of the crankcase 2 into the oil pan 3 empties. To the second outlet 182 of the second valve means 18 is a first outlet pipe 24 completed that - in the flow direction of the internal combustion engine 1 through the fuel-air-mixture inlet line 7 supplied fuel-air mixture viewed - behind the throttle valve 9 into the fuel-air mixture inlet line 7 empties.

Within the first outlet line 24 are two check valves 25 . 26 arranged that a flow of the fuel-air mixture in the direction of the fuel-air mixture inlet line 7 the internal combustion engine 1 allow, however, a flow of a fuel-air mixture from the fuel-air mixture inlet line 7 effectively prevent in the opposite direction.

To the second outlet 172 of the first valve means 17 is a second outlet pipe 250 connected between the first check valve 25 and the second check valve 26 into the first outlet line 24 empties. There is also a first branch line 27 provided the the second outlet line 250 with the fuel-air mixture inlet line 7 the internal combustion engine 1 in an area in front of the throttle valve 9 combines. In the first branch line 27 is a third check valve 28 arranged, which allows the fuel-air mixture from the second outlet line 250 into the fuel-air mixture inlet line 7 the internal combustion engine 1 can flow in. A (back) flow of the fuel-air mixture from the fuel-air mixture inlet line 7 into the second outlet line 250 can by means of the third check valve 28 can be effectively prevented.

The third valve means 19 that to the second inlet 211 of the storage medium 21 is connected with an air supply line 29 connected. The third valve means 19 is set up in a first position, in which it is open, a supply of ambient air to the storage medium 21 to allow so that the storage means 21 can be flushed with purge air. In a second position of the third valve means 19 the air supply to the storage means 21 interrupted accordingly.

That with the internal combustion engine 1 equipped motor vehicle in this embodiment also has a fuel tank with a tank ventilation device 30 that have a second branch line 31 , within which a fourth check valve 32 is arranged between the first check valve 25 and the second outlet 182 of the second valve means 18 with the first outlet line 24 connected is.

The following are details of a method for venting the crankcase 2 the internal combustion engine 1 are explained in more detail. A distinction must first be made as to whether the internal combustion engine 1 is deactivated or activated. If the internal combustion engine 1 is deactivated in a first operating state, the crankcase 2 actively vented to reduce the amount of condensate in the engine oil.

The first valve means 17 is switched so that a fluid flow from the crankcase ventilation device 13 to the storage medium 21 is made possible. That means a flow passage from the inlet 170 to the first outlet 171 of the first valve means 17 is formed, which can be flowed through by the fuel-air mixture. The second valve means 18 is transferred to a switch position in which there is a flow path from the storage means 21 through the air outlet pipe 23 to the oil pan 3 the internal combustion engine 1 releases. A flow from the inlet 180 to the first outlet 181 of the second valve means 18 is therefore possible in this valve position.

With active crankcase ventilation in the deactivated (first) operating state of the internal combustion engine 1 crankcase air containing the condensate is released from the crankcase 2 through the crankcase ventilation device 13 promoted. The crankcase ventilation device oil separator 13 separates the engine oil in the manner already explained above and leads it through the oil return line 16 back into the oil pan 3 , The fuel-air mixture remaining after the oil separation now flows through the first valve means 17 into the storage means provided downstream 21 , Within the storage medium 21 the fuel contained in the fuel-air mixture is stored. In contrast, the air contained in the fuel-air mixture is discharged via the air outlet line 23 preferably directly in the oil pan 3 or alternatively in the crankcase 2 above the oil pan 3 initiated.

The air can mix again with the condensate and as crankcase air from the crankcase 2 into the crankcase ventilation device 13 be promoted so that the above-described active crankcase ventilation process, in which the engine oil is separated and into the oil pan 3 is returned and the fuel contained in the fuel-air mixture remaining after the oil separation in the storage medium 21 is saved, is run again. This measure ensures that the engine oil even when the internal combustion engine is deactivated 1 . in particular when the process is carried out cyclically, effectively separated from the condensate and into the oil pan 3 can be traced back.

If the internal combustion engine 1 is activated and is thus in its second operating state, the first valve means 17 transferred to a second switching position in which the flow path to the storage means 21 is interrupted, so that no more fuel-air mixture in the storage medium 21 is introduced. The flow path of the first valve means 17 thus runs between the inlet in this switch position 170 and the second outlet 172 , Furthermore, the second valve means 18 transferred to a second switching position in which there is no more air from the storage medium 21 via the air supply line 23 into the internal combustion engine 1 can flow in. In this position, the flow path thus runs between the inlet 180 and the second outlet 182 of the second valve means 18 , In addition, in this second operating state, in which the internal combustion engine 1 is activated, the third valve means 19 , which allows an air connection to the environment, at least temporarily in an open position in which the storage means 21 Purge air can be supplied from the environment, which is a regeneration of the storage medium 21 serves. This purge air mixes with that within the storage medium 21 stored fuel and thereby forms a fuel-air mixture, which from the storage means 21 discharged and into the fuel-air mixture inlet line 7 the internal combustion engine 1 is initiated. Because the storage medium 21 cools, a heating device is preferably provided, by means of which the storage means 21 can be heated to enable better regeneration.

The entry of the fuel-air mixture into the fuel-air mixture inlet line 7 the internal combustion engine 1 can, depending on the operating point of the internal combustion engine upstream in front of the intake-side throttle valve 9 , especially on the compressor, or downstream behind the throttle valve 9 respectively. After regeneration of the storage medium 21 can the third valve means 19 preferably be closed again so that the supply of purge air from the environment is interrupted.

Even if the internal combustion engine is activated 1 an active crankcase ventilation by means of the crankcase ventilation device 13 takes place, the fuel-air mixture obtained after the oil separation via the first valve means 17 into the fuel-air mixture inlet line 7 the internal combustion engine 1 brought in. The entry of this fuel-air mixture into the fuel-air mixture inlet line 7 the internal combustion engine 1 can depend on the operating point of the internal combustion engine 1 again upstream in front of the intake-side throttle valve 9 , especially on the compressor, or downstream behind the throttle valve 9 respectively.

By means of the tank ventilation device 30 , which is provided in the exemplary embodiment presented here, the fuel tank can be vented if necessary.

The internal combustion engine 1 with the venting arrangement 100 that depend on the operating state of the internal combustion engine 1 can be operated in different ways, in particular enables a permanent reduction in the condensate in the engine oil through the measures for active crankcase ventilation described above. In particular, this results in a stable lubricating oil viscosity and thus a better lubricating ability of the engine oil. Furthermore, there is advantageously a reduced chemical load on sealing elements, in particular elastomer sealing elements, which seal the internal combustion engine 1 used and can be chemically attacked by the condensate.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 1426130 A [0004]
• DE 102010024172 A1 [0004]
• DE 10335909 A1 [0004]

Claims (10)

Method for venting a crankcase (2) of an internal combustion engine (1), wherein - In a first operating state, in which the internal combustion engine (1) is deactivated, crankcase air, which contains a condensate of fuel, engine oil and possibly water, is conveyed out of the crankcase (2) by means of a crankcase ventilation device (13), - The engine oil contained in the condensate is separated by means of an oil separator and returned to the crankcase (2) or an oil pan (3) of the internal combustion engine (1), - A fuel-air mixture remaining after the oil separation is fed to a regenerable storage means (21) in which the fuel is stored, and - The air contained in the fuel-air mixture is introduced into the internal combustion engine (1). Procedure according to Claim 1 , characterized in that the air contained in the fuel-air mixture is introduced into the oil pan (3) of the internal combustion engine (1). Procedure according to one of the Claims 1 or 2 , characterized in that in a second operating state, in which the internal combustion engine (1) is activated, the storage means (21) for regenerating purge air is supplied and a fuel-air mixture is obtained which is fed to a combustion process of the internal combustion engine (1) becomes. Procedure according to Claim 3 , characterized in that the fuel-air mixture obtained by the regeneration of the storage means (21) is introduced into a fuel-air mixture inlet line (7) of the internal combustion engine (1). Procedure according to Claim 4 , characterized in that the fuel-air mixture obtained by the regeneration of the storage means (21) depending on an operating point of the internal combustion engine upstream or downstream behind a throttle device arranged in the fuel-air mixture inlet line (7), in particular one Throttle valve (9) into which the fuel-air mixture inlet line (7) is introduced. Procedure according to one of the Claims 3 to 5 , characterized in that after the regeneration of the storage means (21) the supply of purge air is interrupted. Procedure according to one of the Claims 3 to 6 , characterized in that in the second operating state of the internal combustion engine (1) crankcase air is conveyed through the crankcase ventilation device (13) and the fuel-air mixture obtained after the oil separation is introduced into the fuel-air-mixture inlet line (7). Procedure according to Claim 7 , characterized in that the fuel-air mixture obtained after the oil separation depending on an operating point of the internal combustion engine upstream or downstream of the throttle device, in particular the throttle valve (9), arranged in the fuel-air mixture inlet line (7), is introduced into the fuel-air-mixture inlet line (7). Procedure according to one of the Claims 1 to 8th , characterized in that a crankcase ventilation device (13) with an integrated oil separator (13) is used. Procedure according to one of the Claims 1 to 9 , characterized in that an activated carbon filter is used as the storage means (21), which is preferably heated during regeneration.

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