INTERNAL COMBUSTION ENGINE FOR A MOTOR VEHICLE, IN PARTICULAR FOR A MOTOR CAR

Description

[0001] 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.

[0002] Such an internal combustion engine for a motor vehicle, in particular for a car, is already known, for example, from DE 10 2007 057 603 A1. The internal combustion engine has an intake tract through which air can flow, in which a compressor is arranged to compress the air flowing through the intake tract. In addition, the internal combustion engine has an exhaust tract through which the exhaust gas of the internal combustion engine can flow, as well as a secondary air system which is fluidly connected to the exhaust tract at at least one inlet point. The secondary air system is fluidly connected to the intake tract at a branch point arranged downstream of the compressor. At the branch point, at least a portion of the air compressed by the compressor can be branched off from the intake tract by means of the secondary air system and introduced into the secondary air system.The air branched off from the intake tract at the branch point and subsequently introduced into the secondary air system can flow through the system and is guided to the inlet point by means of the secondary air system and introduced into the exhaust tract at the inlet point.

[0003] Furthermore, DE 10 2013 226 063 A1 discloses an internal combustion engine comprising a combustion engine, a fresh gas line with a compressor, and an exhaust line with an exhaust aftertreatment device and a temperature sensor. Furthermore, DE 10 2019 008 956 A1 discloses an exhaust system for an internal combustion engine.

[0004] The object of the present invention is to further develop an internal combustion engine of the type mentioned at the outset in such a way that particularly low-emission operation can be achieved.

[0005] This object is achieved by an internal combustion engine having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0006] In order to further develop an internal combustion engine of the type specified in the preamble of patent claim 1 such that particularly low-emission operation can be achieved, the invention provides that the secondary air system is also fluidly connected to the intake tract at a second branching point arranged upstream of the compressor. At the second branching point, at least a portion of the air flowing through the intake tract upstream of the compressor can be branched off from the intake tract by means of the secondary air system and introduced into the secondary air system. The air branched off from the exhaust tract at the second branching point and introduced into the secondary air system can flow through the secondary air system and is guided by the secondary air system to the inlet point and introduced into the exhaust tract as secondary air.Thus, the secondary air system can branch off air from the intake tract both at the first branch point and thus downstream of the compressor and at the second branch point and thus upstream of the compressor and lead it as secondary air to the inlet point and introduce it into the exhaust tract at the inlet point.

[0007] The secondary air system has a secondary air pump, by means of which the air branched off at the second branch point can be conveyed through the secondary air system and conveyed to the inlet point and in particular into the exhaust tract. The invention enables a particularly advantageous and needs-based secondary air injection to be realized. Secondary air injection is to be understood as meaning that the air branched off at the respective branch point can be introduced into the exhaust tract as secondary air at the inlet point, in particular bypassing some or all of the combustion chambers of the internal combustion engine. The air that is branched off from the intake tract at the first branch point and thus downstream of the compressor is also referred to as compressor air.The invention makes it possible, in particular, for example, from a certain point in time, to introduce both the compressor air and the air branched off from the intake tract at the second branching point into the exhaust tract, i.e. to blow it into the exhaust tract. For example, the inlet point is arranged in an exhaust duct, in particular in an outlet duct, whereby the secondary air can be blown into the exhaust tract in a particularly advantageous manner. For example, the inlet point is arranged in an outlet duct formed or delimited in particular by a cylinder head of the internal combustion engine. In particular, several, in particular all, exhaust ducts, in particular outlet ducts, of the internal combustion engine can have a respective inlet point at which the secondary air can be blown into the exhaust tract.The invention makes it possible, in particular, to introduce an advantageously large amount of secondary air into the exhaust tract in all operating ranges of the internal combustion engine, which is also referred to as an internal combustion engine and is preferably designed as a reciprocating piston engine, and thus to enable particularly low-emission operation of the internal combustion engine.

[0008] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the single figure, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0009] The drawing shows in the only figure a schematic representation of an internal combustion engine for a motor vehicle, in particular for a car, with a secondary air system.

[0010] The single figure shows a schematic representation of an internal combustion engine 10 for a motor vehicle, in particular for a car. The internal combustion engine 10 has an engine block 12, also referred to as a cylinder block, which forms cylinders 14 of the internal combustion engine 10. Each cylinder 14 defines a respective combustion chamber in which combustion processes take place during fired operation of the internal combustion engine 10. Exhaust gas from the internal combustion engine 10 results from each combustion process. The internal combustion engine 10 has an intake tract 16 through which air can flow, by means of which the air flowing through the intake tract 16 is guided to and into the combustion chambers of the internal combustion engine 10.The internal combustion engine has an exhaust gas turbocharger 18, which has a compressor 20 arranged in the intake tract 16 and a compressor wheel 22 arranged in the intake tract 16. The air flowing through the intake tract 16 can be compressed by means of the compressor wheel 22 and thus by means of the compressor 20. The compression of the air flowing through the intake tract 16 is also referred to as supercharging, so the compressed air is also referred to as charge air.

[0011] The internal combustion engine 10 also has an exhaust tract 24 through which the exhaust gas from the combustion chamber, and thus the exhaust gas of the internal combustion engine 10, flows. The exhaust gas turbocharger 18 has a turbine 26 arranged in the exhaust tract 24 and a turbine wheel 28 arranged in the exhaust tract 24, which can be driven by the exhaust gas flowing through the exhaust tract 24. The compressor wheel 22 can be driven by the turbine wheel 28 via a shaft 30 of the exhaust gas turbocharger 18, whereby the air flowing through the intake tract 16 can be compressed. An air filter 32 is arranged in the intake tract 16 upstream of the compressor 20, i.e., upstream of the compressor wheel 22, by means of which the air flowing through the intake tract 16 is filtered.In addition, a throttle valve 34 is arranged in the intake tract 16 downstream of the compressor 20 and upstream of the combustion chambers, by means of which, for example, a respective amount of air flowing into the respective combustion chamber can be adjusted.

[0012] The compressor 20 is assigned a recirculation air system 36 with a recirculation air line 38, which is fluidly connected to the intake tract 16 at connection points V1 and V2. By means of the recirculation air line 38, at a connection point V1, at least a portion of the air flowing through the intake tract 16 can be branched off from the intake tract 16 and introduced into the recirculation air line 38. The air introduced into the recirculation air line 38 can flow through the recirculation air line 38 and is guided by the recirculation air line 38 to the inlet point V2 and can flow back into the intake tract 16 at the connection point V2. It can be seen that the connection point V2 is arranged downstream of the air filter 32 and upstream of the compressor wheel 22, wherein the connection point V1 is arranged downstream of the compressor wheel 22 and upstream of the throttle valve 34. The recirculation air system 36 also includes a recirculation air valve 40, which is arranged in the recirculation air line 38.For example, the air flow rate through the recirculation line 38 can be adjusted by means of the recirculation valve 40. In particular, the recirculation valve 40 is designed as an electric recirculation valve.

[0013] The turbine 26 is assigned a bypass device 42 which has a bypass line 44. The bypass line 44 is fluidically connected to the exhaust tract 24 at a connection point V3 and at a connection point V4. By means of the bypass line 44, at least a portion of the exhaust gas flowing through the exhaust tract 24 can be branched off from the exhaust tract 24 at the connection point V3 and introduced into the bypass line 44. The exhaust gas introduced into the bypass line 44 can flow through the bypass line 44 and is guided to the connection point V4 by means of the bypass line 44 and can flow back into the exhaust tract 24 at the connection point V4. The exhaust gas flowing through the bypass line 44 bypasses the turbine 26 and thus does not drive the turbine wheel 28. The bypass line 44 is also referred to as a bypass or wastegate.The bypass device 42 comprises a bypass valve 46, which is also referred to as a bypass valve or wastegate valve and is arranged in the bypass line 44. The bypass valve 46 can be used to adjust the amount of exhaust gas flowing through the bypass line 44. It can be seen that the connection point V3 is arranged upstream of the turbine 26, i.e., upstream of the turbine wheel 28, while the connection point V4 is arranged downstream of the turbine wheel 28, i.e., downstream of the turbine 26.

[0014] Also assigned to the exhaust tract 24 is an exhaust aftertreatment device 48, which is arranged downstream of the turbines 26, in particular downstream of the connection point V4. The exhaust gas from the internal combustion engine can flow through the exhaust aftertreatment device 48 and can aftertreat the exhaust gas. For this purpose, the exhaust aftertreatment device comprises, for example, exhaust aftertreatment elements 50a-c. The exhaust aftertreatment element 50a is designed, for example, as a catalyst, in particular as a three-way catalyst. The exhaust aftertreatment element 50b is designed, for example, as a particulate filter, in particular as a gasoline particulate filter (OPF). The exhaust aftertreatment element 50c is designed, for example, as a catalyst. In particular, the internal combustion engine, also referred to as an internal combustion engine or motor, can be designed as a gasoline engine.

[0015] The internal combustion engine 10 also has a secondary air system 52. The secondary air system 52 is fluidly connected to the intake tract 16 at a first branch point A1. Furthermore, the secondary air system 52 is fluidly connected to the exhaust tract 24 at inlet points E. In particular, at least or exactly one inlet point E can be provided per combustion chamber, at which the secondary air system 52 is fluidly connected to the exhaust tract 24. In particular, it is conceivable for the inlet point E to be arranged, in particular directly, in an exhaust duct, in particular in an exhaust duct. For example, the exhaust duct is formed, i.e., delimited, by a cylinder head of the internal combustion engine 10. The cylinder head is formed separately from the engine block 12 and connected to the engine block 12. In particular, the cylinder head forms a combustion chamber roof for the respective combustion chamber.

[0016] It can be seen that the first branching point A1 is arranged downstream of the compressor 20 and thus downstream of the compressor wheel 22. In the exemplary embodiment shown in the figure, the first branching point A1 is arranged downstream of the connection point V1 and upstream of the throttle valve 34. The secondary air system 52 can branch off at least a portion of the air compressed by the compressor 20 from the intake tract at the branching point A1 and introduce it into the secondary air system 52. Since the branching point A1 is arranged downstream of the compressor wheel 22, the air branched off from the intake tract 16 at the branching point A1 by the secondary air system 52 is also referred to as compressor air. The compressor air can flow into the secondary air system 52 and is guided by the secondary air system 52 to the respective inlet point E and can flow out of the secondary air system 52 at the respective inlet point E and flow into the exhaust tract 24.Thus, the compressor air is introduced as secondary air at the respective inlet point E into the exhaust tract 24, i.e., blown in. The introduction of the air branched off from the intake tract 16 at the branch point A and also referred to as compressor air or secondary air into the exhaust tract 24 at the respective inlet point E is also referred to as secondary air injection.

[0017] In order to achieve particularly low-emission operation of the internal combustion engine 10, the secondary air system 52 is also fluidly connected to the intake tract 16 at a second branch point A2. It can be seen that the second branch point A2 is located upstream of the compressor 20 and thus upstream of the compressor wheel 22, in particular upstream of the connection point V2. By means of the secondary air system 52, at least a portion of the air flowing through the intake tract 16 upstream of the compressor 20 can be branched off from the intake tract 16 at the second branch point A2 and introduced into the secondary air system 52.The air branched off from the intake tract 16 at the second branch point A2 and introduced into the secondary air system 52 is also referred to as pre-compressor air and can be guided by means of the secondary air system 52 to the respective inlet point E and introduced, in particular blown in, at the respective inlet point E as further secondary air into the exhaust tract 24. It can be seen that both the compressor air and the pre-compressor air are used as secondary air, which is branched off from the intake tract 16 at the respective branch point A1 or A2 and introduced into the exhaust tract 24 at the respective inlet point E. The respective inlet point E is arranged upstream of the exhaust gas aftertreatment device 48. In the exemplary embodiment illustrated in the figure, the respective inlet point E is arranged upstream of the turbine 26 and in particular upstream of the connection point V3.

[0018] The secondary air system 52 has a first branch Z1, which is fluidly connected to the intake tract 16 at the second branch point A2 and fluidly connected to the exhaust tract 24 at the respective inlet point E. It can be seen that the secondary air system 52 has a secondary air pump 54, in particular an electrically operated secondary air pump, by means of which the pre-compressor air branched off at the second branch point A2 can be conveyed through the secondary air system 52, in particular through the first branch Z1, and to the respective inlet point E. The secondary air pump 54 is arranged in the first branch Z1.

[0019] The secondary air system 52 also includes a first check valve 56, which is arranged in the first branch Z1 downstream of the secondary air pump 54. The check valve 56 closes in the direction of the secondary air pump 54 and thus prevents a flow of air through the branch Z1 in the direction of the secondary air pump 54. However, in the direction of the respective inlet point E, the check valve 56 opens, so that the check valve 56 permits the flow of the secondary air, in particular the pre-compressor air, from the secondary air pump 54 to the respective inlet point E. The secondary air system 52 has a second branch Z2, which is fluidically connected to the intake tract 16 at the first branch point A1. The second branch Z2 is fluidically connected to the first branch Z1 at an outlet point M. It can be seen that the outlet point M is arranged downstream of the secondary air pump 54, in particular downstream of the check valve 56.The compressor air can thus flow through the second branch Z2. A second check valve 58 of the secondary air system 52 is arranged in the second branch Z2. The second check valve 58 closes toward the outlet point M and opens toward the branch point A.

[0020] The secondary air system 52 also comprises a shut-off valve 60 provided in addition to the check valves 56 and 58, which is arranged in the second branch Z2 and upstream of the check valve 58 and downstream of the branch point A1. The secondary air system 52 has a pressure sensor 62, by means of which a pressure prevailing in the secondary air system 52, in particular downstream of the outlet point M, can be detected. Furthermore, the secondary air system 52 comprises a valve element 64, which is arranged in particular in the branch Z1. In the present case, the valve element 64 is arranged downstream of the outlet point M and in particular downstream of the pressure sensor 62. The valve element 64 is, for example, a secondary air valve, in particular an exhaust gas combination valve. For example, the valve element 64 can be used to adjust the amount of secondary air that is introduced into the exhaust tract 24 at the respective inlet point E.It can be seen that at the outlet point M the compressor air can mix with the pre-compressor air and thus form a total secondary air, wherein by means of the valve element 64 in particular a quantity of the total secondary air can be adjusted which is to be introduced or is introduced into the exhaust tract 24 at the respective inlet point E. In one embodiment it would be conceivable for the check valve 58 to open in the direction of the outlet point M and close in the direction of the branch point A1 and thus, for example, permit a flow of compressor air as secondary air from the branch point A1 to the outlet point M and prevent a reverse flow, i.e. a flow of air from the outlet point M in the direction of the branch point A1.

Claims

1. Internal combustion engine (10) for a motor vehicle, comprising an intake tract (16) through which air can flow, in which a compressor (20) is arranged for compressing the air flowing through the intake tract (16), an exhaust tract (24) through which exhaust gas from the internal combustion engine (10) can flow, and a secondary air system (52) which is fluidically connected to the exhaust tract (24) at at least one inlet point (E) and to the intake tract (16) at a branch-off point (A1) arranged downstream of the compressor (20), at which branch-off point at least a portion of the air compressed by means of the compressor (20) can be branched off from the intake tract (16) by means of the secondary air system (52) and introduced into the exhaust tract (24) as secondary air at the inlet point (E), characterized in that the secondary air system (52) is also fluidically connected to the intake tract (16) at a second branch-off point (A2) arranged upstream of the compressor (20), at which second branch-off point at least a portion of the air flowing through the intake tract (16) upstream of the compressor (20) can be branched off from the intake tract (16) by means of the secondary air system (52) and can be introduced into the exhaust tract (24) as secondary air at the inlet point (E), and has a secondary air pump (54) by means of which the air branched off at the second branch-off point (A2) is to be conveyed through the secondary air system (52) and to the inlet point (E).

2. Internal combustion engine (10) according to claim 1, characterized in that the secondary air system (52) has a branch (Z1) which is fluidically connected to the intake tract (16) at the second branch-off point (A2) and to the exhaust tract (24) at the inlet point (E), in which branch the secondary air pump (52) is arranged.

3. Internal combustion engine (52) according to claim 2, characterized in that a check valve (56) is arranged in the branch (Z1) downstream of the secondary air pump (52), which check valve closes in the direction of the secondary air pump (52) and opens in the direction of the inlet point (E).

4. Internal combustion engine (10) according to either claim 2 or claim 3, characterized in that the secondary air system (52) has a second branch (Z2) which is fluidically connected to the intake tract (16) at the first branch-off point (A1) and to the branch (Z1) at an opening point (M).

5. Internal combustion engine (10) according to claim 4, characterized in that a check valve (58) is arranged in the second branch (Z2), which check valve opens in the direction of the first branch-off point (A1) and closes in the direction of the opening point (M).

6. Internal combustion engine (10) according to claim 5, characterized in that an additional shut-off valve (60) is arranged in the second branch (Z2) upstream of the check valve (58) arranged in the second branch (Z2).

7. Internal combustion engine (10) according to any of claims 4 to 6 and according to claim 3, characterized in that the opening point (M) is arranged downstream of the check valve (56) arranged in the first branch (Z1).

8. Internal combustion engine (10) according to any of the preceding claims, characterized in that the inlet point (E) is arranged in an outlet channel associated with a combustion chamber of the internal combustion engine (10) and formed by a cylinder head of the internal combustion engine (10).