DE102022001526A1 - Internal combustion engine for a motor vehicle, in particular for a motor vehicle - Google Patents

Abstract

The invention relates to an internal combustion engine (10) for a motor vehicle, with an exhaust gas duct (18) through which exhaust gas from combustion chambers (16) of the internal combustion engine (10) can flow, with an intake duct (20) through which air can flow, by means of which air is supplied to the combustion chambers (16 ) can be supplied, with at least one exhaust gas turbocharger (24), which has a turbine (26) arranged in the exhaust gas tract (18) and a compressor (28) arranged in the intake tract (20) and which can be driven by the turbine (26) for compressing the air and with a secondary air system (32), which has a secondary air line (34), by means of which at least part of the air can be branched off from the intake tract (20) at a branch point (A) arranged upstream of the compressor (28) and bypassed as secondary air of the combustion chambers (16) of the internal combustion engine (10) can be introduced into the exhaust tract (18) A secondary air pump (36) is provided in addition to the compressor (28), by means of which the secondary air is to be conveyed through the secondary air line (34) and into the exhaust tract (18).

Description

The invention relates to an internal combustion engine for a motor vehicle, in particular for a motor vehicle according to the preamble of patent claim 1.

Such an internal combustion engine for a motor vehicle, in particular for a motor vehicle, is, for example, already DE 10 2015 015 484 B3 to be taken as known. The internal combustion engine has an exhaust tract through which exhaust gas from combustion chambers of the internal combustion engine can flow, and an intake duct through which air, which is also referred to as fresh air or combustion air, can flow. By means of the intake tract, the air flowing through the intake tract (fresh air or combustion air) can be supplied to the combustion chambers, and thus introduced into the combustion chambers. The internal combustion engine also has at least one exhaust gas turbocharger, which has a turbine arranged in the exhaust tract and drivable by the exhaust gas flowing through the exhaust tract and a compressor arranged in the intake tract and drivable by the turbine. By driving the compressor, the air flowing through the intake tract (fresh air or combustion air) can be compressed by means of the compressor. The internal combustion engine also has a secondary air system, which has a secondary air line. By means of the secondary air line, at least part of the air flowing through the intake tract (combustion air or fresh air) can be branched off from the intake tract at a branch point located upstream of the compressor and introduced into the exhaust tract as secondary air, bypassing the or all combustion chambers of the internal combustion engine.

The object of the present invention is to improve an internal combustion engine of the type mentioned at the outset.

This problem is solved by an internal combustion engine with the features of patent claim 1 . Advantageous configurations with expedient developments of the invention are specified in the remaining claims.

In order to improve an internal combustion engine of the type specified in the preamble of claim 1, a secondary air pump is provided according to the invention in addition to the compressor and is arranged, for example, in the secondary air line, by means of which the secondary air is conveyed through the secondary air line, i.e. through at least one length of the secondary air line, and conveyed into the exhaust tract, can therefore be initiated. The secondary air, which can be conveyed through the secondary air line and into the exhaust tract by means of the secondary air pump, includes that part of the air which is branched off from the intake tract by means of the secondary air line at the branching point and then flows through the secondary air line, i.e. the part of the air that is out by means of the secondary air line at the branching point to understand the air branched off from the intake tract and, in particular, then flowing through the secondary air line.

The internal combustion engine also includes a pre-compressor that is provided in addition to the compressor and in addition to the secondary air pump and can be supplied with the secondary air, i.e. with the branched part of the air flowing through the secondary air line, which is in particular in the secondary air line and upstream of the secondary air pump, which is also simply referred to as Air pump or pump is called, is arranged. The pre-compressor can be driven by at least part of the air compressed by the compressor. The air compressed by the compressor is also referred to as charge air, so that the pre-compressor can be driven by at least part of the charge air. By driving the pre-compressor, the secondary air can be pre-compressed by means of the pre-compressor, the secondary air pre-compressed, ie compressed, by means of the pre-compressor being able to be supplied to the secondary air pump. In other words, the secondary air pump can be supplied with the secondary air compressed by the supercharger, so that the secondary air precompressed by the supercharger can be or is supplied to a suction side of the secondary air pump, also referred to as the inlet side. As a result, a particularly advantageous injection of secondary air can be implemented by means of the secondary air system. For example, during or through the driving of the supercharger, the charge air driving the supercharger is at least partially expanded. For example, after the charge air has driven the precompressor, it is introduced, ie introduced, in particular by means of a return line from the precompressor into a crankcase ventilation of the internal combustion engine, as a result of which particularly low-emission operation can be achieved. As a result of the invention, the secondary air pump, which is also referred to as a secondary air compressor or is designed as a secondary air compressor, can be operated with a higher suction pressure prevailing on the suction side in comparison to conventional solutions.

The secondary air pump is preferably an electric pump, ie a pump that can be operated electrically.

The invention is based in particular on the following findings and considerations: Conventional electrical secondary air pumps with an electrical voltage of 12 V have a limited delivery pressure of approximately 300 to 400 mbar. If such a conventional secondary air pump conveys the secondary air upstream of the compressor and, for example, downstream of an air filter arranged in the intake tract, in particular sucks it in, so that the secondary air has ambient pressure, the secondary air can only be introduced into the exhaust tract at those points at which a compared to 300 to 400 mbar lower pressure prevails. However, when the secondary air is blown in after the exhaust valves of the internal combustion engine in its exhaust ducts or exhaust duct, the pressure there increases sharply, especially when the internal combustion engine, which is also simply referred to as a motor and is designed, for example, as a reciprocating piston engine, is subjected to a higher load, for example during strong acceleration after a cold start or after or when exiting an underground car park, for example. It would be conceivable to use secondary air pumps with a higher electrical voltage of 48 V, for example, in order to achieve a higher delivery pressure. However, such secondary air pumps are more expensive and space-consuming. It would also be conceivable for the secondary air pump to branch off the secondary air from the intake tract at a point arranged downstream of the compressor, so that the secondary air is at least part of the charge air, which also has a charge pressure designated as p2 and caused by the compressor. However, this can lead to problems with regard to the thermal stability of the secondary air pump, so that separate cooling of the electronics of the secondary air pump may be necessary, for example, since the charge air is very hot due to its compression and, in particular, too hot to act as a cooling medium. In addition, this can lead to problems with regard to media resistance, since the charge air can contain an oil mist from blow-by gases. The consequence of this would be high technical complexity and high costs.

The problems and disadvantages mentioned above can now be avoided by the invention. The invention makes it possible to use the air compressed by the compressor, and therefore the charge air and thus its charge pressure, to drive the supercharger by means of the air compressed by the compressor or by means of the charge pressure and thus the secondary air from a clean air line of the intake tract upstream of the compressor and to promote preferably downstream of the aforementioned air filter, in particular divert or suck. The secondary air is therefore filtered and therefore sufficiently clean air. Compared to conventional solutions, the supercharger allows a higher pressure of the secondary air, also referred to as air pressure, to be realized on the suction side of the secondary air pump, but without leading the charge air, i.e. its charge air mass flow, via or through the secondary air pump. The supercharger can therefore increase the pressure compared to conventional solutions, the pressure increase being sufficient to inject the secondary air into the outlet channel, for example against a pressure that is present in an outlet channel of the internal combustion engine, also referred to as p3. Thus, for example, the secondary air can be introduced into the exhaust tract at an introduction point, that is to say blown in, which is arranged downstream of the or all combustion chambers and in particular upstream of the turbine. At the same time, the invention makes it possible to use an electrical pump with an electrical voltage of 12 V, which is advantageous in terms of installation space and cost-effectiveness, as the secondary air pump. The invention is thus a cost-effective solution which enables low-emission operation of the internal combustion engine without loss of performance, particularly during a cold start.

Further advantages, features and details of the invention result from the following description of a preferred exemplary embodiment and from the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own, without going beyond the scope of the leave invention.

• 1 eine schematische Darstellung einer Verbrennungskraftmaschine eines Kraftfahrzeugs; und
• 2 eine schematische Darstellung eines Vorverdichters eines Sekundärluftsystems der Verbrennungskraftmaschine.

The drawing shows in:

• 1 a schematic representation of an internal combustion engine of a motor vehicle; and
• 2 a schematic representation of a supercharger of a secondary air system of the internal combustion engine.

Elements that are the same or have the same function are provided with the same reference symbols in the figures.

1 shows a schematic representation of a simply referred to as a motor or internal combustion engine and present as a reciprocating engine tor trained internal combustion engine 10 for a motor vehicle, in particular for a motor vehicle. This means that the motor vehicle has the internal combustion engine 10 in its fully manufactured state and can be driven by the internal combustion engine 10 . The internal combustion engine 10 has an engine block 12 embodied, for example, as a cylinder housing, in particular as a cylinder crankcase, which has cylinders 14 . The respective cylinder 14 delimits a respective combustion chamber 16 of the internal combustion engine 10 at least partially. During fired operation of the internal combustion engine 10, combustion processes take place in the combustion chambers 16, resulting in exhaust gas from the internal combustion engine 10. The internal combustion engine 10 has an exhaust tract 18 through which the exhaust gas from the combustion chambers 16 can flow. Furthermore, the internal combustion engine 10 has an intake tract 20 through which air can flow. The air is also referred to as combustion air or fresh air. The fresh air flowing through the intake tract 20 can be guided to and into the combustion chambers 16 by means of the intake tract 20 . An air filter 22 is arranged in the intake tract 20 and is used to filter the fresh air. The internal combustion engine 10 also has an exhaust gas turbocharger 24 which has a turbine 26 which is arranged in the exhaust gas section 18 and can be driven by the exhaust gas flowing through the exhaust gas section 18 and a compressor 28 . The compressor 28 can be driven by the turbine 26 via a shaft 30 of the exhaust gas turbocharger 24 . By driving the compressor 28, the fresh air flowing through the intake tract 20 can be compressed by means of the compressor 28, in particular to a charge pressure designated as p2. A charge air cooler 33 is also arranged in the intake tract 20 and is arranged in the intake tract 20 downstream of the compressor 28 and in particular upstream of the combustion chambers 16 . The compressed and thus heated fresh air is cooled by means of the charge air cooler 33, the fresh air compressed by means of the compressor 28 also being referred to as charge air. It can be seen that the charge air has the pressure p2 in the intake tract 20 downstream of the compressor 28 and upstream of the charge air cooler 33 . Upstream of the compressor 28 and downstream of the air filter 22, the fresh air in the intake tract 20 has a pressure p0 which is lower than the charge pressure and which corresponds in particular to the ambient pressure.

Furthermore is off 1 recognizable that the exhaust gas in the exhaust tract 18 upstream of the turbine 26 and in particular downstream of the combustion chambers 16 has a pressure p3, and the exhaust gas in the exhaust tract 18 downstream of the turbine 26 has a pressure p4 that is lower than the pressure p3.

The internal combustion engine 10 also has a secondary air system 32 which includes a secondary air line 34 . The secondary air line 34 is fluidically connected or connectable to the intake tract 20 at a branch point A. In addition, the secondary air line 34 is fluidically connected or can be connected to the exhaust tract 18 at an introduction point E. In particular, the introduction point E is arranged in an outlet channel, which is assigned to one of the combustion chambers 16 and through which the exhaust gas from one combustion chamber can flow. It can be seen that the inlet point E is arranged upstream of the turbine 26 and downstream of the combustion chambers 16, so that the exhaust gas has the pressure p3 at the inlet point E in the exhaust gas tract 18. The branching point A is arranged in the intake tract 20 downstream of the air filter 22 and upstream of the compressor 28, so that at the branching point A the air in the intake tract 20 has the pressure p0. In addition, the fresh air at branch point A is clean air and is therefore sufficiently clean, since the fresh air at branch point A was filtered by means of air filter 22 and was not yet compressed by compressor 28 . At least part of the fresh air can be branched off from the intake tract 20 at the branch point A by means of the secondary air line 34 . The fresh air branched off from the intake tract 20 at branch point A by means of the secondary air line 34 can flow through the secondary air line 34 and be introduced as secondary air by means of the secondary air line 34, bypassing the or all combustion chambers 16 at the inlet point E into the exhaust tract 18. This means that the fresh air flowing through the secondary air line 34 comes from the intake tract 20 and is referred to as secondary air and on its way from branch point A and thus from the intake tract 20 to the introduction point E and into the exhaust tract 18 bypasses all or all of the combustion chambers 16, that is, it does not flow through any of the combustion chambers 16 . By means of the secondary air, for example, an in 1 not shown exhaust aftertreatment device, which is arranged in the exhaust tract 18, effectively and efficiently heated and / or kept warm. The introduction or introduction of the secondary air into the exhaust tract 18 is also referred to as blowing in or blowing in secondary air.

In order to now be able to implement a particularly advantageous secondary air injection, the secondary air system 32 has a secondary air pump 36 which is arranged in the secondary air line 34 and can preferably be operated electrically, by means of which the secondary air can be conveyed through the secondary air line 34 and can be conveyed into the exhaust tract 18 at the introduction point E. It can be seen that the secondary air pump 36 is provided in addition to the compressor 28 . The secondary air system also includes 32 a pre-compressor 38 provided in addition to the compressor 28 and in addition to the secondary air pump 36, which in 1 shown embodiment in the secondary air line 34 and is arranged upstream of the secondary air pump 36. As in 1 is illustrated by a dashed arrow 40, the supercharger 38 can be driven by at least part of the fresh air compressed by means of the compressor 28, and consequently by at least part of the charge air. This means that at least part of the charge air can be fed to the supercharger 38, specifically from a point arranged downstream of the compressor 28 and upstream of the charge air cooler 33, so that the charge air with which the supercharger 38 can be or is supplied has the charge pressure p2 having. By driving the supercharger 38, the secondary air flowing through the secondary air line 34 can be precompressed by means of the supercharger 38. Since the secondary air pump 36 is arranged downstream of the supercharger 38 in the secondary air line 34, the secondary air pump 36 is precompressed by means of the supercharger 38, i.e. compressed Secondary air can be supplied or is supplied. As a result, a particularly high pressure level can be achieved on a suction side of secondary air pump 36, with secondary air pump 36 pumping the secondary air from the suction side to a pressure side of secondary air pump 36 and via the pressure side to inlet point E and at inlet point E into exhaust tract 18. It can be seen that the precompressor 38 can increase the pressure of the secondary air, in particular on the suction side of the secondary air pump 36, as a result of which the secondary air can be conveyed against the pressure p3 into the exhaust gas tract 18 and in particular into the outlet channel, and can therefore be blown in.

2 shows a possible embodiment of the supercharger 38 in a schematic representation. The supercharger 38 can be designed, for example, as a displacement piston, rotor or turbocharger. At the in 2 shown embodiment, the supercharger 38 is designed as a turbocharger and thus as a turbomachine. The supercharger 38 has a turbine wheel 42 which can be supplied with the charge air having the pressure p2 and can be driven by the charge air having the charge pressure p2 and is therefore rotatable about an axis of rotation, in particular relative to a housing. Furthermore, the supercharger 38 includes a compressor wheel 44, which can be driven by the turbine wheel 42 via a shaft 46 of the supercharger 38 and is therefore rotatable about the axis of rotation, in particular relative to the housing. By driving, i.e. by turning, the compressor wheel 44, the secondary air having the pressure p0 (ambient pressure) is precompressed by means of the compressor wheel 44, in particular to a pressure, also referred to as admission pressure, which is greater than the pressure p0 and, for example, less than or equal to the boost pressure p2 . By means of the secondary air line 34, the secondary air compressed by means of the compressor impeller 44 and thus by means of the precompressor 38 and having the stated admission pressure is guided to the secondary air pump 36, which is thus supplied with the precompressed secondary air and thus having the admission pressure and subsequently the secondary air to the Introduction point E promotes and conveys at the introduction point E into the exhaust tract 18 . Because the charge air drives the turbine wheel 42, the charge air is expanded from the pressure p2 (charge pressure), for example to an expansion pressure which is lower than the charge pressure p2 and greater than or equal to the pressure p0. The charge air driving the turbine wheel 42 is hot and dirty because it contains oil, for example, and is therefore supplied to a crankcase ventilation of the internal combustion engine 10 after it has driven the turbine wheel 42 . The secondary air compressed by the compressor wheel 44 is advantageously clean and advantageously cold. It can be seen that the charge air driving the turbine wheel 42 and the secondary air compressed by the compressor wheel 44 are kept separate so that the secondary air is advantageously cool and advantageously clean. This means that the usually hot and dirty charge air does not have to be used as secondary air.

Reference List

10

internal combustion engine

12

engine block

14

cylinder

16

combustion chamber

18

exhaust tract

20

intake tract

22

air filter

24

exhaust gas turbocharger

26

turbine

28

compressor

30

Wave

32

secondary air system

33

intercooler

34

secondary air line

36

secondary air pump

38

booster

40

Dashed arrow

42

turbine wheel

44

compressor wheel

46

Wave

p0

Print

p2

boost pressure

p3

Print

p4

Print

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102015015484 B3 [0002]

Claims (3)

Internal combustion engine (10) for a motor vehicle, with an exhaust gas section (18) through which exhaust gas from combustion chambers (16) of the internal combustion engine (10) can flow, with an intake section (20) through which air can flow, by means of which the air can be supplied to the combustion chambers (16), with at least one exhaust gas turbocharger (24), which has a turbine (26) arranged in the exhaust tract (18) and a compressor (28) arranged in the intake tract (20) and drivable by the turbine (26) for compressing the air, and with a secondary air system (32), which has a secondary air line (34), by means of which at least part of the air can be branched off from the intake tract (20) at a branching point (A) arranged upstream of the compressor (28) and as secondary air, bypassing the combustion chambers (16 ) of the internal combustion engine (10) can be introduced into the exhaust tract (18), characterized by : - a secondary air pump (36) provided in addition to the compressor (28), by means of which d ie secondary air is to be conveyed through the secondary air line (34) and into the exhaust tract (18); and - a supercharger (38) provided in addition to the compressor (28) and in addition to the secondary air pump (36), which can be supplied with the secondary air and can be driven by at least part of the air compressed by the compressor (28), by means of which, while driving the supercharger (38) the secondary air can be precompressed and then fed to the secondary air pump (36). Internal combustion engine (10) after claim 1 characterized by a discharge line, by means of which the air driving the precompressor (38) can be introduced into a crankcase (12) and/or into a crankcase ventilation of the internal combustion engine (10) after the precompressor (38) has been driven. Internal combustion engine (10) after claim 1 or 2 , characterized in that the supercharger (38) is designed as a displacement piston compressor or turbomachine.

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