internal combustion engine

Abstract

Internal combustion engine (1), comprising: a drive unit (2), a fresh gas line (4) by means of which filtered fresh gas can be supplied to the drive unit (2), an exhaust system (5) connected to the drive unit (2), and an exhaust gas turbocharger (3) comprising a compressor (30) connected to the fresh gas line (4) and configured to compress the fresh gas, a turbine (31) coupled to the compressor (30) and connected to the exhaust system (5), and an electric drive device (33) configured to provide auxiliary drive to the compressor (30), wherein the fresh gas line (4) comprises a primary air system (42) with a primary air line (43) and a control means for controlling the primary air mass flow, and a secondary air system (60) with a secondary air line (61) leading into the exhaust system (5) and with at least one control means for controlling the secondary air mass flow.characterized in that the secondary air system (60) has at least one pressure sensor means (63, 66a, 66b, 68, 69) which is configured to calculate a secondary air mass flow and to perform a system diagnosis of the secondary air system (60).

Description

The present invention relates to an internal combustion engine comprising a drive unit, a fresh gas line by means of which filtered fresh gas can be supplied to the drive unit, an exhaust system connected to the drive unit, and an exhaust gas turbocharger comprising a compressor connected to the fresh gas line and configured to compress the supplied fresh gas, a turbine coupled to the compressor and connected to the exhaust system, and an electric drive device configured to provide auxiliary drive to the compressor, wherein the fresh gas line comprises a primary air system with a primary air line and a control means for controlling the primary air mass flow, and a secondary air system with a secondary air line that opens into the exhaust system and with at least one control means for controlling the secondary air mass flow. Exhaust gas turbocharging plays a crucial role in the development of internal combustion engines. This is primarily due to the increasing demands for improved efficiency, reduced emissions, and increased power output. To reduce fuel consumption and, consequently, CO2 emissions from internal combustion engines, development trends are increasingly moving towards smaller engine displacements, often referred to as "downsizing." This results in the wider adoption of exhaust gas turbochargers to achieve correspondingly high specific power outputs. A known charging concept from the prior art is electrically assisted exhaust gas turbocharging, in which the exhaust gas turbocharger of an internal combustion engine has an additional electric drive unit. This electric drive unit provides additional power to a compressor of the exhaust gas turbocharger, generating switchable, additional torque to drive the exhaust gas turbocharger, particularly at low engine speeds. Electrically assisted exhaust gas turbochargers can be used to improve the responsiveness of the internal combustion engine and to increase steady-state full-load torque at low engine speeds. For example, if insufficient exhaust gas enthalpy is available during the cold start phase of the internal combustion engine, the turbine of the exhaust gas turbocharger is bypassed via a wastegate.Nevertheless, a sufficiently high boost pressure can be generated in this operating state using the electric drive unit. Internal combustion engines known from the prior art, in addition to a primary air system that supplies the engine with fresh air-fuel mixture, have a secondary air system that is activated after a cold start. Such a secondary air system typically comprises a secondary air line, a secondary air valve, and an electric secondary air pump for injecting filtered intake air into the exhaust ports of a cylinder head of the engine. The electric secondary air pump is used solely for this purpose: to trigger a post-combustion reaction in a section of the exhaust system between the exhaust valves of the engine and a catalytic converter, in conjunction with unburned excess fuel from the combustion process. This reaction brings the catalytic converter up to its operating temperature more quickly and further oxidizes the existing exhaust emissions. An internal combustion engine of the type mentioned above with an electrically assisted exhaust gas turbocharger and a secondary air system for injecting filtered fresh gas into an exhaust system is known, for example, from DE 10 2015 015 484 B3. The present invention aims to provide an internal combustion engine of the type mentioned above which has improved diagnostic capabilities and higher operational reliability. The solution to this problem is a generic internal combustion engine with the features of the characterizing part of claim 1. The dependent claims relate to advantageous embodiments of the invention. An internal combustion engine according to the invention is characterized in that the secondary air system has at least one pressure sensor, which is configured to calculate a secondary air mass flow and to perform system diagnostics of the secondary air system. The at least one pressure sensor, by means of which the secondary air mass flow can be determined, provides improved diagnostic capabilities, particularly for the secondary air system, and preferably also enables on-board diagnostics. Immediately after starting the internal combustion engine, it is in a so-called cold start phase, in which it is not yet operating at its target operating temperature. This means that an exhaust gas purification device of the internal combustion engine is also not operating at its target operating temperature.During the cold start phase of the internal combustion engine, filtered and compressed fresh gas is injected into the exhaust system via the secondary air line. Preferably, the fresh gas is injected into at least one exhaust manifold and thus into the exhaust ports of the engine unit assigned to the cylinders of the internal combustion engine. This, in conjunction with unburned excess fuel from the combustion process in the exhaust system between the exhaust valves of the engine unit and the catalytic converter, triggers a post-reaction. This allows the catalytic converter to reach its operating temperature more quickly and the existing exhaust emissions to be further oxidized. Furthermore, this process can also regenerate a particulate filter, particularly a gasoline particulate filter, in the exhaust system. In one embodiment, it is proposed that the control means for controlling the secondary air mass flow be designed as a pressure-tight valve (towards the fresh gas side) in the closed state and as a continuously variable valve in the control state. This can preferably include an EGR valve (exhaust gas recirculation valve). Preferably, at least one of the pressure sensor means can be arranged downstream of the control means, e.g. the EGR valve. In an advantageous embodiment, it is proposed that the secondary air system comprises at least one secondary air valve located upstream of the exhaust system. This secondary air valve has two switching positions. In a first switching position, the secondary air valve is open, allowing secondary air from the secondary air line, particularly in the area of ​​an exhaust manifold, to flow into the exhaust system. In a second switching position, the secondary air valve is closed, thus preventing secondary air from flowing from the secondary air line into the exhaust system. Furthermore, in the closed position of the secondary air valve, the secondary air line and the EGR valve can be protected from damage caused by high exhaust gas temperatures, since closing the secondary air valve effectively prevents exhaust gases from entering the secondary air system. In one embodiment, the at least one control means for regulating the secondary air mass flow can be designed as an adjustable secondary air valve. The adjustable secondary air valve is designed to allow continuous adjustment of its opening from a fully closed to a fully open position. Preferably, the adjustable secondary air valve can be continuously variable and provide position feedback. In this embodiment, all functions of the secondary air throttle valve and the secondary air valve can advantageously be completely taken over by the adjustable secondary air valve, thus simplifying the design of the secondary air system. Furthermore, it is advantageous if the adjustable secondary air valve is pressure-tight from the fresh air side when closed. Preferably, at least one of the pressure sensor means can be arranged downstream of the controllable secondary air valve. This pressure sensor means can, in particular, be arranged downstream immediately after the controllable secondary air valve. In a particularly advantageous embodiment, the operation of the internal combustion engine can be controlled such that, in at least one operating state with the secondary air valve at least partially open, exhaust gases from the engine can be introduced into the secondary air line. Thus, the secondary air system with the secondary air line can be used not only during the cold start phase, but also in a partial load range, a full load range, or a near-full load range. This significantly expands the application possibilities of the secondary air system. In an alternative embodiment, at least one control element for the secondary air mass flow can be designed as an exhaust gas recirculation (EGR) valve. The EGR valve is preferably designed to allow continuous adjustment of its opening from a fully closed to a fully open position. In this embodiment, all functions of the secondary air throttle valve and the secondary air valve can advantageously be completely taken over by the EGR valve, thus simplifying the design of the secondary air system. Preferably, at least one of the pressure sensor means can be arranged downstream of the exhaust gas recirculation valve. This pressure sensor means can, in particular, be arranged downstream immediately after the exhaust gas recirculation valve. In a preferred embodiment, it is proposed that the internal combustion engine has at least one charge air cooler arranged within the fresh air stream. This charge air cooler is designed to cool the compressed fresh air before it is fed to the combustion process within the engine via the primary air system. In one embodiment, it is possible that the secondary air line branches off from the fresh gas stream behind the charge air cooler in the direction of flow of the fresh gas. In an alternative embodiment, the secondary air line can also branch off from the fresh air stream upstream of the charge air cooler in the direction of fresh air flow. This results in a higher temperature of the secondary air introduced into the exhaust system when the secondary air system is activated, compared to embodiments where the secondary air line branches off from the fresh air stream downstream of the charge air cooler in the direction of fresh air flow. This leads to a higher inlet temperature of the secondary air entering the exhaust gas of the internal combustion engine, thus also increasing its reactivity. Further features and advantages of the present invention will become clear with reference to the following description of preferred embodiments and the accompanying figures. Figure 1 shows a highly simplified schematic representation of an internal combustion engine designed according to a first embodiment of the present invention during a cold start phase; Figure 2 shows a highly simplified schematic representation of an internal combustion engine designed according to a second embodiment of the present invention during a cold start phase; Figure 3 shows a highly simplified schematic representation of an internal combustion engine designed according to a third embodiment of the present invention during a cold start phase; Figure 4 shows a highly simplified schematic representation of the internal combustion engine according to Figure 3 in a near-full-load operating condition; Figure 5 shows the engine in a near-full-load operating condition.5 a schematically simplified representation of an internal combustion engine, which has been slightly modified in its construction based on the embodiment shown in Fig. 3 and Fig. 4. In the figures, identical or functionally identical components were each given the same reference symbols. With reference to Fig. 1, an internal combustion engine 1, which is designed according to a first embodiment of the present invention, comprises a fuel-operated, multi-row drive unit 2, which in this case has two cylinder banks 20, 21, each with three cylinders 23a, 23b, 23c, 24a, 24b, 24c, and an exhaust gas turbocharger 3. The exhaust gas turbocharger 3 has, in a manner known per se, a compressor 30 for compressing a fresh gas and a turbine 31, which is operatively connected to the compressor 30 via a common shaft. The internal combustion engine 1 comprises a fresh gas stream 4 to which the compressor 30 of the exhaust gas turbocharger 3 is connected. By means of the compressor 30, a fresh gas, in particular fresh air, can be drawn in and compressed on a suction side, so that the fresh gas has a higher pressure on a pressure side of the compressor 30 than on the suction side. Before the fresh gas, in particular the fresh air, is compressed by the compressor 30, it passes through an air filter 40 located upstream of the compressor 30, which filters the fresh gas. The fresh gas stream 4 also includes a charge air cooler 41, which is arranged between the compressor 30 and the drive unit 2.This charge air cooler 41 is designed to cool the compressed fresh gas before it is supplied to the combustion process within the drive unit 2 via a primary air system 42, which has a primary air line 43 and an engine throttle valve 44, which is arranged within the primary air line 43 to regulate the primary air mass flow. The internal combustion engine 1 also has an exhaust system 5, which includes an exhaust pipe 50 and, due to the two-row design of the drive unit 2, a total of two exhaust manifolds 51, 52. The exhaust gases generated during the combustion process from cylinders 23a, 23b, 23c, 24a, 24b, 24c of the two cylinder banks 20, 21 can be combined by means of the exhaust manifolds 51, 52 and discharged via the common exhaust pipe 50, to which the exhaust manifolds 51, 52 are connected. Furthermore, the exhaust system 5 has an exhaust gas purification device 10, which includes an exhaust catalyst 11 and a particulate filter 12 downstream of it. The exhaust catalyst 11 is an electrically heated catalyst connected to an electrical power supply unit 7. The turbine 31 of the exhaust gas turbocharger 3 is connected to the exhaust pipe 50 of the exhaust system 5, so that the turbine 31 can be set in rotation by an exhaust gas mass flow. This involves converting a portion of the flow energy of the exhaust gas mass flow into kinetic energy to drive the turbine 31. This also sets the compressor 30, which is mechanically connected to the turbine 31 via the common shaft, in rotation, enabling it to compress the supplied fresh gas. Furthermore, the exhaust gas turbocharger 3 has a wastegate 32. By means of this wastegate 32, at least a portion of the exhaust gas mass flow can be diverted past the turbine 31 and directly into the exhaust gas cleaning device 10, if required. The exhaust gas turbocharger 3 is an electrically assisted exhaust gas turbocharger 3. It has a switchable electric drive device 33, by means of which the rotational movement of the compressor 30 can be assisted as needed, particularly during a cold start phase of the internal combustion engine 1. The electric drive device 33 is connected to the electrical power supply unit 7 via a pulse inverter 8. The internal combustion engine 1 also has a central control unit 9 for controlling its operation. Furthermore, in addition to the primary air system 42, the fresh air intake system 4 has a secondary air system 60, the function of which will be explained in more detail below. The secondary air system 60 has a secondary air line 61, which in this embodiment branches off downstream behind the charge air cooler 41. The secondary air system 60 also includes a control device for controlling the secondary air mass flow, which in this case is designed as an EGR valve 62. In the direction of flow of the compressed fresh air, two pressure sensors 63, 68 are arranged upstream and downstream of the EGR valve 62. These pressure sensors 63, 68 are configured to calculate the secondary air mass flow and to perform system diagnostics of the secondary air system 60. The two pressure sensors 63, 68 are preferably connected to the central control unit 9 and, in particular, enable on-board diagnostics of the secondary air system 60.The first pressure sensor device 63 enables, in particular, a diagnosis of the piping system. In this embodiment, the secondary air system 60 further comprises two secondary air valves 64a, 64b, which are arranged upstream of the EGR valve 62 and upstream of the exhaust manifolds 51, 52 of the two cylinder banks 20, 21 of the drive unit 2. A first secondary air valve 64a is arranged upstream of the exhaust manifold 51 of the first cylinder bank 20, whereas a second secondary air valve 64b is arranged upstream of the exhaust manifold 52 of the second cylinder bank 21. The two secondary air valves 64a, 64b, which are designed as unrestricted valves, are connected to the central control unit 9 so that they can be actuated by it. The two secondary air valves 64a, 64b have two switching positions. In a first switching position, the secondary air valves 64a, 64b are open, so that secondary air from the secondary air line 61 can flow into the exhaust system 5 in the area of ​​the exhaust manifolds 51, 52.In a second switching position, the secondary air valves 64a and 64b are closed, thus preventing the inflow of secondary air from the secondary air line 61 into the exhaust system 5. In the closed position of the secondary air valves 64a and 64b, the secondary air line 61 and the EGR valve 62 are also protected from damage caused by high exhaust gas temperatures, as closing the secondary air valves 64a and 64b effectively prevents exhaust gases from entering the secondary air system 60. In addition to regulating the secondary air mass, the control unit for the secondary air mass (EGR valve 62) also has the task of preventing unwanted fresh air flow to one side of the exhaust system when closed. For this reason, the EGR valve is designed to provide a mechanical seal against fresh air, thus preventing fluidic communication. Immediately after the internal combustion engine 1 is started, it is in a so-called cold start phase, during which it is not yet operating at its target operating temperature. This means that the exhaust gas purification device 10 is also not operating at its target operating temperature. During the cold start phase of the internal combustion engine 1, filtered fresh gas, compressed by the compressor 30, is therefore injected into the exhaust system 5 via the secondary air line 61, which branches off upstream from the fresh gas stream 4 behind the charge air cooler 41, with the secondary air valves 64a, 64b open. Preferably, the fresh gas is injected into the exhaust manifolds 51, 52 and thus into the exhaust ports of the drive unit 2 assigned to the cylinders 23a, 23b, 23c, 24a, 24b, 24c.This, in conjunction with unburned excess fuel from combustion in the exhaust system 5 between the exhaust valves of the drive unit 2 of the internal combustion engine 1 and the exhaust catalyst 11, triggers a post-reaction. In this way, the exhaust catalyst 11 is brought up to its operating temperature more quickly, and the existing exhaust emissions are further oxidized. Furthermore, this also allows the particulate filter 12 to be regenerated. With reference to Fig. 2, a second embodiment of an internal combustion engine 1 is shown. In terms of its basic structure, this embodiment is based on the first embodiment and differs from it only in that the secondary air line 61 does not branch off from the fresh air stream 4 between the charge air cooler 41 and the engine throttle valve 42, but rather upstream of the charge air cooler 41. This results in the secondary air introduced into the exhaust system 5 being at a higher temperature when the secondary air system 60 is activated than in the first embodiment. This leads to a higher inlet temperature of the secondary air in the exhaust gas of the internal combustion engine 1, thus also increasing its reactivity. In the two embodiments described above, the calculation of the secondary air mass flow can also be performed sensorlessly using the modeled pressure in the exhaust channel downstream of the EGR valve 62, thus eliminating the need for the second pressure sensor 68. However, the first pressure sensor 63 upstream of the EGR valve 62 is always required for calculating the secondary air mass flow. With reference to Fig. 3, a third embodiment of an internal combustion engine 1 is shown there. The basic design also has numerous similarities with the two embodiments described above, so that a description of these similarities will be omitted here. Therefore, only the differences, which all relate to the different design of the secondary air system 60, will be explained in more detail below. The secondary air line 61 branches off – as in the embodiment shown in Fig. 2 – from the fresh air stream 4 between the compressor 30 and the charge air cooler 41. A throttle valve is not provided in the secondary air line 61. Furthermore, no secondary air valves are provided to open or close the secondary air supply to the exhaust system 5. A pressure sensor 69 is also provided in the secondary air line 61. In this embodiment, the secondary air supply is controlled by two adjustable secondary air valves 65a, 65b, each arranged upstream of the exhaust manifolds 50, 51 of cylinder banks 20, 21 of the drive unit 2 in the direction of secondary air flow. These adjustable secondary air valves 65a, 65b are connected to the control unit 9, can be actuated by it, and are designed to allow continuous adjustment of the opening from a fully closed to a fully open position. From a functional point of view, the two adjustable secondary air valves 65a, 65b thus constitute control means for controlling the secondary air mass flow and can therefore assume the function of the secondary air throttle valve 62 of the embodiment according to Fig. 1 and Fig. 2.Furthermore, the two adjustable secondary air valves 65a, 65b enable the secondary air supply to the exhaust system 5 to be opened and closed, thus also taking over the function of the secondary air valves 64a, 64b of the embodiments according to Fig. 1 and Fig. 2. As a result, in this embodiment, the secondary air throttle valve 62 and the two secondary air valves 64a, 64b, which are provided in the embodiments described above, can advantageously be omitted. The functions of the secondary air throttle valve 62 and the secondary air valves 64a, 64b are thus completely taken over by the adjustable secondary air valves 65a, 65b, which are also connected to the control unit 9 and can be controlled by it. Preferably, the adjustable secondary air valves 65a, 65b can be designed to be continuously adjustable and have position feedback.Furthermore, it is advantageous if the adjustable secondary air valves 65a, 65b are pressure-tight from the fresh air side when closed. Downstream of each of the two controllable secondary air valves 65a, 65b, a pressure sensor 66a, 66b is arranged. These pressure sensors 66a, 66b, together with the pressure sensor 69 in the secondary air line 61, are configured to calculate the secondary air mass flow rate and to perform system diagnostics of the secondary air system 60. The pressure sensors 66a, 66b, 69 are connected to the central control unit 9 and, in particular, enable on-board diagnostics of the secondary air system 60. In an alternative embodiment, the calculation of the secondary air mass flow rate can also be performed sensorlessly via the modeled pressure in the outlet duct. For calculating the secondary air mass flow rate, the pressure sensor 69 is provided in the secondary air line 61, which can also be used, in particular, for diagnosing the duct system. In this variant, the pressure sensors 66a, 66b can then be omitted. During the cold start phase of the internal combustion engine 1, in this embodiment as well, filtered fresh gas compressed by the compressor 30 is injected into the exhaust system 5 via the secondary air line 61, which branches off from the fresh gas stream 4 upstream of the charge air cooler 41, with the secondary air valves 65a, 65b at least partially open. Preferably, the fresh gas is injected into the exhaust manifolds 51, 52 and thus into the exhaust ports of the drive unit 2 assigned to the cylinders 23a, 23b, 23c, 24a, 24b, 24c. This, in conjunction with unburned excess fuel from the combustion in the exhaust system 5, triggers a post-reaction between the exhaust valves of the drive unit 2 of the internal combustion engine 1 and the exhaust catalyst 11. In this way, the exhaust catalyst 11 is brought up to its operating temperature more quickly, and the existing exhaust emissions are further oxidized.Furthermore, this also enables the regeneration of the particle filter 12. The components of the secondary air system 60 of the internal combustion engine 1 according to Fig. 3 can advantageously be used not only during the cold start phase, but also in a near-full-load operating condition of the internal combustion engine 1. This will be explained in more detail below with reference to Fig. 4. In this second operating mode, the secondary air system 60 of the internal combustion engine 1 is now used as an exhaust gas recirculation system. In this operating state of the internal combustion engine 1, the engine throttle valve 44 is very wide open, and at high engine speeds, the pressure of the fresh gas downstream of the compressor 30 is lower than the pressure of the exhaust gases in the exhaust line 50 upstream of the turbine 31 of the exhaust gas turbocharger 3. The controllable secondary air valves 65a, 65b of the secondary air system 60 are largely open. The hot exhaust gas, recirculated via the secondary air line 61, the flow direction of which is symbolized by corresponding arrows in Fig. 4, is cooled together with the fresh gas downstream of the compressor 30 of the exhaust gas turbocharger 3 by means of the charge air cooler 41 and then fed to the primary air system 42.With sufficient dimensioning of the charge air cooler 41, an improvement in the knock limit as well as a reduction in NOx emissions and a lower exhaust gas temperature can be achieved through the inert, cooled exhaust gas due to the new combustion chamber gas composition (isentropic coefficients). With reference to Fig. 5, a fourth embodiment of an internal combustion engine 1 will be explained in more detail below. This embodiment represents a further development of the third embodiment and builds upon it. In this embodiment, an inlet point for the exhaust gas of the drive unit 2 is positioned either switchably or permanently upstream of a second charge air cooler 45 behind the engine throttle valve 44. This allows exhaust gas recirculation not only in the near-full-load range but also in the partial-load range of the internal combustion engine 1. This results in advantages in terms of fuel consumption and pollutant emissions, particularly NOx emissions.In this embodiment, the secondary air system 60 has an additional switchable valve element 67, which is designed and can be switched by means of the control device 9 such that, during the cold start phase of the internal combustion engine 1, compressed secondary air can be supplied to the exhaust system 5 via the secondary air line 61 in a first switching position, and in a second switching position the exhaust gas from the drive unit 2 can be returned and introduced into the primary air line 43 in front of the second charge air cooler 45. Instead of the controllable secondary air valves 65a, 65b present in the embodiments according to Fig. 3, Fig. 4 to Fig. 5, exhaust gas recirculation valves can also be provided in alternative embodiments, which can also control the secondary air supply.

Claims

Internal combustion engine (1), comprising: a drive unit (2), a fresh gas line (4) by means of which filtered fresh gas can be supplied to the drive unit (2), an exhaust system (5) connected to the drive unit (2), and an exhaust gas turbocharger (3) comprising a compressor (30) connected to the fresh gas line (4) and configured to compress the fresh gas, a turbine (31) coupled to the compressor (30) and connected to the exhaust system (5), and an electric drive device (33) configured to provide auxiliary drive to the compressor (30), wherein the fresh gas line (4) comprises a primary air system (42) with a primary air line (43) and a control means for controlling the primary air mass flow, and a secondary air system (60) with a secondary air line (61) leading into the exhaust system (5) and with at least one control means for controlling the secondary air mass flow.characterized in that the secondary air system (60) has at least one pressure sensor means (63, 66a, 66b, 68, 69) which is configured to calculate a secondary air mass flow and to perform a system diagnosis of the secondary air system (60). Internal combustion engine (1) according to claim 1, characterized in that the at least one control means for controlling the secondary air mass flow is designed as an EGR valve (62). Internal combustion engine (1) according to claim 2, characterized in that at least one of the pressure sensor means (63, 66a, 66b, 68, 69) is arranged downstream of the EGR valve (62). Internal combustion engine (1) according to one of claims 1 to 3, characterized in that the secondary air system (60) has at least one secondary air valve (64a, 64b) which is arranged upstream of the exhaust system (5). Internal combustion engine (1) according to claim 1 , characterized in that the at least one control means for controlling the secondary air mass flow is designed as an adjustable secondary air valve (65a, 65b). Internal combustion engine (1) according to claim 5, characterized in that at least one of the pressure sensor means (63, 66a, 66b, 68, 69) is arranged downstream behind the controllable secondary air valve (65a, 65b). Internal combustion engine (1) according to one of claims 5 or 6, characterized in that the operation of the internal combustion engine (1) can be controlled in such a way that in at least one operating state with the secondary air valve (65a, 65b) at least partially open, exhaust gases from the drive unit (2) can be introduced into the secondary air line (61). Internal combustion engine (1) according to one of claims 1 to 7, characterized in that the internal combustion engine (1) has at least one charge air cooler (41) which is arranged within the fresh gas stream (4). Internal combustion engine (1) according to claim 8, characterized in that the secondary air line (61) branches off from the fresh gas line (4) behind the charge air cooler (41) in the direction of flow of the fresh gas. Internal combustion engine (1) according to claim 8, characterized in that the secondary air line (61) branches off from the fresh gas line (4) in the direction of flow of the fresh gas in front of the charge air cooler (41).

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