Internal combustion engine for a motor vehicle, especially for a car

Description

[0001] The invention relates to an internal combustion engine for a motor vehicle, in particular for a motor car, according to the original concept of claim 1.

[0002] Such an internal combustion engine for a motor vehicle, in particular for a car, is already known, for example, from DE 100 38 7 24 A1. The internal combustion engine has an exhaust tract through which exhaust gas from at least one combustion chamber of the engine flows, and a secondary air line through which secondary air flows. The secondary air flowing through the secondary air line can be introduced into the exhaust tract by means of this secondary air line. The internal combustion engine also has an ignition device arranged in the exhaust tract, by means of which a mixture can be ignited that comprises the secondary air introduced into the exhaust tract and, in particular, unburned and combustible fuel components. Furthermore, the internal combustion engine has an intake tract through which fresh air flows, and through which the fresh air flowing through the intake tract can be introduced into the combustion chamber.Fresh air can be a component of a combustion mixture that may include fresh air as well as, optionally, recirculated exhaust gas and / or unburned fuel. Furthermore, DE 100 31 924 A1 discloses a method for verifying the effectiveness of at least one measure for heating a catalyst in the exhaust gas of an internal combustion engine. Additionally, DE 10 2008 032 601 A1 discloses a method for adjusting the state of an exhaust gas stream from an internal combustion engine of a motor vehicle.

[0003] The object of the present invention is to improve an internal combustion engine of the type mentioned at the outset.

[0004] This problem is solved by an internal combustion engine with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] To improve an internal combustion engine of the type specified in the preamble of claim 1, the invention provides that the secondary air line is fluidically connected to the intake manifold at a branch point. This branch point is located downstream of a compressor arranged in the intake manifold and designed to compress the fresh air, and upstream of a throttle valve arranged in the intake manifold, by means of which the quantity of fresh air supplied to the combustion chamber can be adjusted. At the branch point, at least a portion of the fresh air can be diverted from the intake manifold via the secondary air line and introduced into the exhaust manifold as secondary air. In other words, at least a portion of the fresh air can be diverted from the intake manifold at the branch point and introduced into the secondary air line.The portion of fresh air diverted from the intake manifold at the branch point and introduced into the secondary air line is routed to the exhaust manifold via the secondary air line and introduced into the exhaust manifold as secondary air. This means that the diverted portion of fresh air is used as secondary air, which is introduced into the exhaust manifold and utilized to combust the unburned and combustible fuel components contained in the exhaust gas, which originate from the combustion chamber and have entered the exhaust manifold unburned.

[0006] Furthermore, it is provided that the ignition device is designed as a spark plug, by means of which the fuel components in the mixture comprising the secondary air can be ignited in a targeted and required manner and subsequently burned in a simple and therefore cost- and weight-saving way.

[0007] The invention enables, for example, the post-ignition or combustion of the fuel components in combination with the secondary air with a particularly short time delay during a cold start of the internal combustion engine, so that, for example, an exhaust aftertreatment device arranged in the exhaust system can be heated effectively and quickly for the purpose of treating the exhaust gas. This ensures particularly low-emission operation of the internal combustion engine.

[0008] The spark plug enables rapid ignition of the fuel-air mixture in the exhaust system, also known as the exhaust tract, thereby facilitating emissions combustion. Emissions combustion means that by igniting and burning the mixture, any emissions contained in the exhaust gas, particularly unburned and combustible fuel components, can be burned off. This prevents, for example, excessive emissions of unburned hydrocarbons (HC). Furthermore, the exhaust aftertreatment system, which may include a catalyst, can be heated quickly and effectively, thus reaching its optimal operating temperature (light-off temperature) and minimizing the cold start and subsequent cold-start phase.Compared to other heating systems, the spark plug is particularly simple and therefore cost-effective.

[0009] The internal combustion engine is operated, for example, after or during its cold start with secondary air, i.e., with secondary air injection. This means that the secondary air is introduced, in particular injected, into the exhaust system. The secondary air bypasses, for example, all combustion chambers of the internal combustion engine and therefore does not originate from the combustion chamber. According to the invention, the secondary air line has a dual function. On the one hand, the secondary air line is used to utilize at least the aforementioned portion of the fresh air from the intake manifold as secondary air and to introduce the secondary air into the exhaust system. On the other hand, the secondary air line can be used as a bypass air line, particularly in combination with a bypass air valve, since the branch point is located downstream of the compressor or a compressor wheel and upstream of the throttle valve.For example, if the compressor is used to compress the fresh air, and then the throttle valve closes abruptly, fresh air can be drawn from the intake manifold via the secondary air line, thus preventing excessive braking of the compressor wheel due to the abrupt closing of the throttle valve.

[0010] In the invention, a valve element designed as the aforementioned bypass valve is associated with the secondary air line. This valve element allows adjustment of the amount of fresh air to be introduced into the secondary air line at the branch point and into the exhaust system as secondary air. In other words, the valve element is a so-called combination valve. Firstly, the combination valve can be used to adjust the amount of fresh air or secondary air to be introduced into the secondary air line. Secondly, the combination valve can be used to divert at least a portion of the fresh air initially arranged between the compressor wheel and the throttle valve from the intake manifold.This means that, via the valve element acting as a bypass valve, when the initially open throttle valve closes, at least a portion of the fresh air initially arranged between the compressor and the throttle valve can be diverted from the intake manifold as bypass air and returned from the diversion point to a point located upstream of the compressor, where it can be introduced into the intake manifold. Thus, the invention essentially combines a secondary air system with a bypass air system, or rather, integrates these systems. This allows the number of parts and the cost of the internal combustion engine to be kept to a particularly low level.

[0011] Another embodiment is characterized by the fact that a turbine driven by the exhaust gas is arranged in the exhaust tract. This allows for a particularly advantageous and efficient operation of the internal combustion engine.

[0012] Preferably, an inlet point is provided at which the secondary air line is fluidically connected to the exhaust tract and the secondary air from the secondary air line can be introduced into the exhaust tract, thereby enabling a particularly advantageous operation.

[0013] In a particularly advantageous embodiment of the invention, the inlet point is arranged in a bypass channel that is flow-wise parallel to the turbine, bypassing the turbine with at least a portion of the exhaust gas. This allows the secondary air to be introduced into the exhaust tract without unduly affecting the turbine or its operation.

[0014] In an alternative embodiment of the invention, the inlet point is arranged downstream or upstream of the turbine in the exhaust tract and is connected in series with the turbine in terms of flow technology, which allows for a particularly advantageous operation.

[0015] Furthermore, according to the invention, at least one or more spark plugs are used in the exhaust system, in particular between an exhaust valve of the combustion chamber and the exhaust aftertreatment system. By heating the spark plugs, for example, a rich combustion chamber mixture from the combustion chamber can be ignited and subsequently combusted in conjunction with the secondary air introduced into the exhaust system, wherein, for example, the combustion chamber mixture and the secondary air form the aforementioned mixture. With the aid of the spark plug, the combustion chamber mixture in conjunction with the secondary air can be combusted as required and, in particular, at an early stage, so that the cold start can be kept short and is particularly advantageous with regard to emissions and comfort.

[0016] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0017] The drawing shows in: Fig. 1 is a schematic representation of an internal combustion engine according to a first embodiment; and Fig. 2 is a schematic representation of the internal combustion engine according to a second embodiment.

[0018] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0019] Fig. 1 Figure 10 shows a schematic representation of an internal combustion engine 10, designed here as a reciprocating piston engine, for a motor vehicle, in particular for a motor vehicle preferably designed as a passenger car. Thus, the motor vehicle in its fully manufactured state comprises the internal combustion engine 10 and can be driven by means of the internal combustion engine 10. The internal combustion engine 10 comprises a cylinder housing 12, which forms or delimits several cylinders 14 of the internal combustion engine 10. Each cylinder 14 partially delimits a respective combustion chamber 16 of the internal combustion engine 10. During firing 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.

[0020] The internal combustion engine 10 has an exhaust tract 18 through which exhaust gas from the combustion chambers 16 can flow. The internal combustion engine 10 also includes a secondary air duct 20 through which secondary air can flow, and by means of which the secondary air flowing through the secondary air duct 20 can be introduced into the exhaust tract 18, in particular at an inlet point E. The secondary air flowing through the secondary air duct 20 bypasses the combustion chambers 16 of the internal combustion engine 10 and thus does not flow through the combustion chambers 16 or through any combustion chamber 16 of the internal combustion engine 10.

[0021] The internal combustion engine 10 also has at least one or more spark plugs 22, 24 arranged in the exhaust tract, wherein a mixture in the exhaust tract 18 can be ignited by means of the respective spark plug 22 or 24. The mixture comprises the secondary air introduced into the exhaust tract 18 and unburned and therefore still combustible fuel components that have escaped unburned from at least one of the combustion chambers 16 and entered the exhaust tract 18. Furthermore, the internal combustion engine 10 comprises an intake tract 26 through which fresh air flows, and by means of which the fresh air flowing through the intake tract 26 is directed to and into the combustion chambers 16.

[0022] The internal combustion engine 10 comprises an exhaust gas turbocharger 28, which has a compressor 30 arranged in the intake tract 26 and a turbine 32 arranged in the exhaust tract 18. The turbine 32 is driven by the exhaust gas, and the compressor 30 is driven by the turbine 32, in particular via a shaft 34 of the exhaust gas turbocharger 28. By driving the compressor 30, the fresh air flowing through the intake tract 26 is compressed by means of the compressor 30.

[0023] In the direction of flow of the fresh air passing through the intake tract 26, a charge air cooler 36 is arranged downstream of the compressor 30 and, in particular, upstream of the combustion chambers 16. The fresh air is cooled by means of this cooler before it flows into the combustion chambers 16. A throttle valve 38 is also arranged in the intake tract 26. The throttle valve 38 is located upstream of the charge air cooler 36 and downstream of the compressor 30. The amount of fresh air supplied to the combustion chambers 16 is controlled by means of the throttle valve 38. Fig. 1 It is further apparent that, in particular by means of an exhaust manifold 40 arranged in the exhaust tract 18, two first combustion chambers 16 are combined to form a first exhaust flow 42 and two second combustion chambers 16 to form a second exhaust flow 44. Each first combustion chamber 16 is assigned a first exhaust line 46a or 46b, formed, for example, by the exhaust manifold 40, wherein the exhaust lines 46a and 46b are combined to form the common exhaust flow 42 or open into the exhaust flow 42. Each second combustion chamber 16 is assigned a second exhaust line 48a or 48b, wherein the exhaust lines 48a and 48b open into the common exhaust flow 44 or are combined to form the exhaust flow 44. The turbine 32 is thus preferably designed as a twin-flow turbine.

[0024] Turbine 32 is associated with a bypass channel 50, which branches off from exhaust pipe 46b. With respect to exhaust pipes 46a, b and 48a, b, the bypass channel 50 preferably branches exclusively from exhaust pipe 46b. The bypass channel 50 is fluidically connected to the exhaust tract 18 at a first connection point and at a second connection point. In particular, the bypass channel 50 is fluidically connected to exhaust pipe 46b at the first connection point. At the first connection point, at least a portion of the exhaust gas flowing through exhaust pipe 46b can be diverted from the exhaust pipe 46b and introduced into the bypass channel 50. The exhaust gas introduced into the bypass channel 50 is conveyed to the second connection point and reintroduced into the exhaust tract 18 at the second connection point.The first connection point is located upstream of the turbine 32, while the second connection point is located downstream of the turbine 32. Thus, the exhaust gas flowing through the bypass channel 50 bypasses the turbine 32. This means that the exhaust gas flowing through the bypass channel 50 does not drive the turbine 32. A valve element 52 is associated with the bypass channel 50, by means of which the amount of exhaust gas flowing through the bypass channel 50 can be adjusted. Therefore, the power output of the turbine 32, and thus the boost pressure at which the fresh air is compressed by the compressor 30, can be set, and in particular regulated, by means of the bypass channel 50 and the valve element 52.

[0025] Furthermore, the exhaust tract 18 has a connecting line 54 through which the bypass channel 50 and the exhaust stream 44 are fluidically connected or can be connected. The valve element 52 is also referred to as a wastegate flap or wastegate valve, since the power of the turbine 32 and the boost pressure can be adjusted, in particular regulated, by means of the valve element 52. The valve element 52 is also referred to as a stream connection flap or stream connection valve, since, for example, the amount of exhaust gas flowing through the connecting line 54 can be adjusted by means of the valve element 52.For example, if the valve element 52 is closed, so that the bypass channel 50 is closed, the exhaust gas which flows into the bypass channel 50 at the first connection point flows via the connecting line 54, for example into the exhaust gas flux 44, so that the exhaust gas flux 44 is fluidically connected via the connecting line 54 to the bypass channel 50 or to the exhaust gas line 46 b.

[0026] It is evident that spark plug 22 is located in the connecting line 54. Spark plug 24 is located downstream of turbine 32. It is evident that the bypass channel 50 is flow-wise parallel to turbine 32. Spark plug 24 is flow-wise parallel to turbine 32 and located downstream of turbine 32 in the exhaust tract 18. Spark plug 22 can be flow-wise very close to turbine 32 and located upstream of turbine 32, or spark plug 22 can be flow-wise parallel to turbine 32.

[0027] To implement the secondary air supply in a particularly simple and therefore cost-effective, space-saving, and weight-efficient manner, the secondary air line 20, which is fluidically connected to the exhaust tract 18 at the inlet point E, is fluidically connected to the intake tract 26 at a branch point A. This branch point A is located downstream of the compressor 30 and upstream of the throttle valve 38 in the direction of flow of the fresh air flowing through the intake tract 26. At branch point A, at least a portion of the fresh air from the intake tract 26 can be diverted into the secondary air line 20. The fresh air introduced into the secondary air line 20 flows through it and is guided to the inlet point E, where it is introduced into the exhaust tract 18 as secondary air.A valve element 56 is associated with the secondary air line 20, by means of which the proportion, i.e., the quantity, of the secondary or fresh air flowing through the secondary air line 20 can be adjusted. Preferably, the valve element 56 is a combination valve, also simply referred to as a combination valve, since the valve element 56 is used, on the one hand, to adjust the proportion, i.e., the quantity, of secondary air flowing through the secondary air line 20. On the other hand, the valve element 56 is used, for example, as a bypass valve, via which, for example, when the initially open throttle valve 38 is closed quickly, at least a portion of the fresh air initially arranged between the compressor 30 and the throttle valve 38 can be diverted from the intake manifold 26. This prevents excessive deceleration of the compressor 30 or its compressor wheel when the throttle valve 38 is closed abruptly.Out of . Fig. 1 It is evident that a secondary air system for supplying the secondary air is combined with a thrust recirculation system, thus eliminating the need for actuators and pumps compared to conventional solutions. This allows the secondary air system and the thrust recirculation system to be implemented in a way that is lighter, more compact, and more cost-effective.

[0028] For example, the inlet point A is located in the exhaust manifold 40, also known as the exhaust manifold, so that secondary air is blown or introduced into the exhaust manifold. The introduction or blowing of secondary air into the exhaust tract 18 is also referred to as air injection or secondary air injection. The spark plug 24 is preferably located in the area of ​​an outlet of the turbine 32. If, for example, at least one of the combustion chambers 16 provides a rich combustion chamber mixture, which comprises unburned and therefore combustible and preferably liquid fuel, i.e., the aforementioned fuel components, the rich combustion chamber mixture is mixed with the secondary air, thereby forming the aforementioned mixture. By means of the respective spark plug 22 or 24, the mixture can be ignited selectively and at an early stage, so that particularly low-emission operation is possible.

[0029] Fig. 2Figure 1 shows a second embodiment of the internal combustion engine 10. In this second embodiment, the inlet point E is, for example, spaced apart from the exhaust manifold and is arranged, in particular, downstream of the turbine 32, specifically at an outlet of a turbine rotor of the turbine 32, whose turbine rotor, for example, comprises a turbine wheel. Furthermore, it is conceivable that the inlet point E is arranged along the turbine rotor. This can be understood, in particular, to mean that, for example, the inlet point E is arranged at the same level as the turbine wheel in the flow direction of the exhaust gas flowing through the exhaust tract 18.

[0030] One advantage of the internal combustion engine 10 is that the secondary air can be injected into an area with only low back pressure. This ensures a sufficient pressure differential between the branch point A, located downstream of the compressor 30, and the inlet point E. Furthermore, flow turbulence after the turbine 32 can be used to combust the secondary air particularly efficiently with the fuel components or with the rich combustion chamber mixture. Additionally, the spark plugs 22 and 24 are used for ignition of the mixture, a process also known as spark ignition, which allows for efficient, early, and cost-effective ignition that saves space and installation costs.

[0031] Preferably, an exhaust aftertreatment device for treating the exhaust gas is arranged downstream of the respective spark plug 22 or 24 and also downstream of the inlet point E. The exhaust aftertreatment device comprises, for example, at least one catalyst, which can be designed as a three-way catalyst or as an SCR catalyst. Ignition and combustion of the mixture allows the exhaust aftertreatment device to be heated particularly quickly and efficiently, thus enabling particularly efficient heating, especially of the catalyst, since a turbine housing of the turbine 32 does not need to be heated. In particular, existing components, especially in the form of the bypass valve, can be used to achieve particularly low-emission operation of the internal combustion engine 10. Reference symbol list

[0032] 10 Internal combustion engine 12 Cylinder housing 14 Cylinder 16 Combustion chamber 18 Exhaust system 20 Secondary air line 22 Spark plug 24 Spark plug 26 Intake system 28 Exhaust turbocharger 30 Compressor 32 Turbine 34 Shaft 36 Intercooler 38 Throttle valve 40 Exhaust manifold 42 Exhaust flow 44 Exhaust flow 46a, 46b Exhaust pipe 48a, 48b Exhaust pipe 50 Bypass duct 52 Valve element 54 Connecting pipe 56 Valve element A Branch point E Inlet point

Claims

1. Internal combustion engine (10) for a motor vehicle, comprising an exhaust tract (18) through which exhaust gas from at least one combustion chamber (16) of the internal combustion engine (10) can flow, comprising a secondary air line (20) through which secondary air can flow and by means of which the secondary air flowing through the secondary air line (20) can be introduced into the exhaust tract (18), comprising at least one ignition device (22, 24) arranged in the exhaust tract (18), by means of which ignition device a mixture comprising the secondary air introduced into the exhaust tract (18) and fuel components is to be ignited in the exhaust tract (18), and comprising an intake tract (26) through which fresh air can flow and by means of which the fresh air flowing through the intake tract (26) can be introduced into the combustion chamber (16), the secondary air line (20) being fluidically connected to the intake tract (26) at a branch point (A) that is arranged downstream of a compressor (30) arranged in the intake tract (26) and designed to compress the fresh air and that is arranged upstream of a throttle valve (38) arranged in the intake tract (26), by means of which throttle valve a quantity of fresh air to be supplied to the combustion chamber (16) can be adjusted, at which branch point at least a portion of the fresh air can be diverted from the intake tract (26) by means of the secondary air line (20) and introduced as the secondary air into the exhaust tract (18), the ignition device (22, 24) being in the form of a spark plug (22, 24), the fuel components being contained in the exhaust gas, originating from the combustion chamber (16) and entering the exhaust tract (18) unburned from the combustion chamber (16), and a valve element (56) being provided, characterized in that the valve element (56) is in the form of a combination valve, by means of which, on the one hand, the portion can be adjusted, and on the other hand, via the valve element (56) as a recirculating-air valve, when the initially open throttle valve (38) is closed at least a portion of the fresh air initially located between the compressor (30) and the throttle valve (38) can be diverted as recirculating air from the intake tract (26) and can be returned from the branch point (A) to a point arranged upstream of the compressor (30) and can be introduced into the intake tract (30) at that point.

2. Internal combustion engine (10) according to claim 1, characterized in that a turbine (32) that can be driven by the exhaust gas is arranged in the exhaust tract (18).

3. Internal combustion engine (10) according to claim 2, characterized by an inlet point (E) at which the secondary air line (20) is fluidically connected to the exhaust tract (18) and the secondary air from the secondary air line (20) can be introduced into the exhaust tract (18).

4. Internal combustion engine (10) according to claim 3, characterized in that the inlet point (E) is arranged in a bypass duct (50) that is connected in parallel with the turbine (32) in terms of flow and via which at least a portion of the exhaust gas bypasses the turbine (32).

5. Internal combustion engine (10) according to claim 3, characterized in that the inlet point (E) is arranged in the exhaust tract (18) downstream or upstream of the turbine (32) and is connected in series with the turbine (32) in terms of flow.