Method for the installation testing of an exhaust aftertreatment component of an exhaust system and a secondary air system for an internal combustion engine and motor vehicle

Abstract

Method for the installation test of an exhaust aftertreatment component (28) of an exhaust system (20) and a secondary air system (30) for an internal combustion engine (10), comprising the following steps: - Activation of the secondary air system (30), wherein air is supplied to the exhaust system (20) by a secondary air pump (32), - Installation test of the secondary air system (30), wherein an air pressure provided by the control of the secondary air pump (32) is compared with an air pressure present in the flow direction after the secondary air pump (32), wherein if the pressure difference between the two air pressures exceeds a first difference threshold value, a conclusion is drawn that the secondary air system (30) is installed incorrectly, - Installation test of the exhaust aftertreatment component (28), wherein an air pressure in the direction of flow upstream of the exhaust aftertreatment component (28) and an air pressure in the direction of flow downstream of the exhaust aftertreatment component (28) are compared, wherein if the pressure difference between the two air pressures exceeds a second difference threshold value, a conclusion is drawn that the exhaust aftertreatment component (28) is incorrectly installed.

Description

[0001] The invention relates to a method for testing the installation of an exhaust aftertreatment component of an exhaust system and a secondary air system for an internal combustion engine. The invention also relates to a motor vehicle.

[0002] Typically, a secondary air system is tested for proper installation by controlling a secondary air pump in a defined manner, thereby causing an air flow at a predetermined air pressure. Downstream of the secondary air pump, the air pressure is measured by a pressure sensor, and a pressure difference between the air pressure caused by the secondary air pump and the air pressure measured by the pressure sensor is determined. The pressure difference is then compared with a difference threshold value. The difference threshold value already takes into account pressure losses that inevitably occur between the secondary air pump and the point where the pressure is measured by the pressure sensor, even in an intact secondary air system. If the pressure difference exceeds the difference threshold value, there is a fault in the secondary air system.

[0003] An installation test of an exhaust aftertreatment component during initial assembly of the exhaust aftertreatment component or reinstallation during repair or maintenance work is usually carried out by recording the exhaust pressure upstream of the exhaust aftertreatment component and the exhaust pressure downstream of the exhaust aftertreatment component with the internal combustion engine running, and comparing a pressure difference determined from the exhaust pressures with a difference threshold. If the pressure difference is above the difference threshold, it is concluded that the exhaust aftertreatment component is incorrectly installed, for example, due to a leak at a connection point to another component of the exhaust system, or that the exhaust aftertreatment component is impaired in its operability, for example, due to a blockage in the exhaust aftertreatment component.

[0004] DE 10 2016 225 758 A1 discloses a motor vehicle with an internal combustion engine, an exhaust system having at least one particulate filter, and a secondary air system for introducing air into the exhaust system. Monitoring of the particulate filter and the secondary air system is performed by evaluating the pressure measurement signals provided by a secondary air pressure sensor of the secondary air system. Furthermore, JP 2006 - 138 261 A discloses that a fault diagnosis of a secondary air system can be performed using a connectable diagnostic device, wherein the fault diagnosis is based on a detected secondary air pressure.

[0005] The disadvantage of such an installation test of the exhaust aftertreatment component is that the installation test is carried out based on exhaust gas pressures and thus while the combustion engine is running, which means that exhaust gases are emitted into the environment during each installation test.

[0006] The object of the invention is to provide a method for testing the installation of an exhaust aftertreatment component of an exhaust system and a secondary air system for an internal combustion engine, by means of which the emission of exhaust gases can be reduced or avoided.

[0007] The problem is solved by the features of claim 1.

[0008] According to the invention, the installation test of the exhaust aftertreatment component is carried out using an air flow introduced into the exhaust system by the secondary air system. To test the installation of the exhaust aftertreatment component, an air pressure in the flow direction upstream of the exhaust aftertreatment component and an air pressure in the flow direction downstream of the exhaust aftertreatment component are compared. If the pressure difference between the two air pressures exceeds a second difference threshold, it is concluded that the exhaust aftertreatment component is incorrectly installed.

[0009] In particular, the installation test of the secondary air system and the installation test of the exhaust gas aftertreatment component are carried out simultaneously, so that an air flow is caused by the control of the secondary air pump of the secondary air system and, on the one hand, a pressure difference is formed from the air pressure provided by the secondary air pump and the air pressure of a pressure sensor and, on the other hand, a pressure difference is formed from the two air pressures before and after the exhaust gas aftertreatment component, wherein both differential pressures are each adjusted with a corresponding first and second differential threshold value.

[0010] In this way, both systems can be tested for proper installation, especially simultaneously, which can reduce the time required for the installation test. Furthermore, the combustion engine does not need to be running for the installation test of the exhaust aftertreatment component, as the pressure difference required for the installation test is caused by the airflow, meaning no exhaust gases are released into the environment during the installation test. In other words, the installation test of the secondary air system and the exhaust aftertreatment component is performed with the combustion engine inactive.

[0011] The object is also achieved by a motor vehicle which has an internal combustion engine, an exhaust system which has at least one exhaust aftertreatment component, a secondary air system for introducing air into the exhaust system, a sensor device and a control unit, wherein the control unit has an installation test module which is designed to carry out the method according to claim 1.

[0012] During the installation test, the secondary air pump of the secondary air system is controlled via the installation test module in such a way that an air flow emanates from the secondary air pump with an air flow caused by the corresponding control of the secondary air pump. For the installation test of the secondary air system, the air pressure at a point spaced apart from the secondary air pump in the direction of air flow is preferably recorded by a first pressure sensor of the sensor device and transmitted to the installation test module, wherein a pressure difference is determined from the air pressure provided by the control of the secondary air pump and the air pressure recorded by the sensor device, which pressure difference is in turn compared with a first difference threshold value. If the determined pressure difference exceeds the first differential pressure threshold value, it is concluded that there is an installation error or a defect in the secondary air system, for example the secondary air pump.At the same time, the installation test module performs an installation test of the exhaust aftertreatment component, in particular a particulate filter. The air flow caused by the secondary air pump flows through the exhaust system to the exhaust aftertreatment component and through the exhaust aftertreatment component. The air pressure in the direction of air flow upstream and downstream of the exhaust aftertreatment component is recorded, preferably by a second and a third pressure sensor of the sensor device, and transmitted to the installation test module. A pressure difference between the two air pressures is determined in the installation test module.The determined pressure difference is then compared in the installation test module with a second differential pressure threshold value stored in the installation test module. If the second differential pressure threshold is exceeded, the determined pressure difference indicates an installation error, a blockage, or something similar in the exhaust aftertreatment component. Finally, a message is preferably output to a user interface indicating that an installation error or a defect in the secondary air system and / or the exhaust aftertreatment component exists.

[0013] Preferably, the second and third pressure sensors form a differential pressure sensor, whereby only a single sensor is required to determine the pressure difference.

[0014] An embodiment of the invention is explained in more detail with reference to the drawings.

[0015] Figure shows schematically an arrangement of an internal combustion engine, an exhaust system and a secondary air system.

[0016] The figure shows an internal combustion engine 10, an exhaust system 20 and a secondary air system 30 of a motor vehicle.

[0017] The internal combustion engine 10 has a first group 12 of cylinders 121, 122, 123 and a second group 14 of cylinders 141, 142, 143. The first group 12 and the second group 14 are, for example, a first and a second cylinder bank of the internal combustion engine 10. This is merely an exemplary embodiment of the internal combustion engine 10. Alternative configurations or arrangements of the cylinders are also possible.

[0018] The exhaust system 20 serves to discharge exhaust gases generated during operation of the internal combustion engine 10 from the cylinders 121, 122, 123, 141, 142, 143. The exhaust system 20 has a first branch 22 for the exhaust gases of the first group 12, a second branch 24 for the exhaust gases of the second group 14, and a common section 26, wherein the two branches 22, 24 open into the common section 26 and the exhaust gases of both groups 12, 14 are discharged through the common section 26. In the present embodiment, an exhaust gas aftertreatment component 28, in particular a particulate filter 29, is arranged in the common section 26. In addition, an exhaust gas turbocharger and other exhaust gas aftertreatment components, such as a catalytic converter, can also be arranged in the common section 26.

[0019] The secondary air system 30 comprises a secondary air pump 32, a first secondary air valve 34, and a second secondary air valve 36. In the illustration shown in the figure, a secondary air flow delivered by the secondary air pump 32 is divided into a first secondary air branch 381 and a second secondary air branch 382, ​​wherein the division can be controlled by appropriately controlling the secondary air valves 34, 36. The secondary air pump 32 and the secondary air valves 34, 36 are controlled by a control unit 40, wherein the secondary air pump 32 and the secondary air valves 34, 36 can be controlled individually.

[0020] The control unit 40 is preferably an engine control unit which, for example, also controls the fuel metering and / or ignition of the internal combustion engine 10 during operation of the internal combustion engine 10 and processes signals from other sensors (not shown) for operating parameters of the internal combustion engine 10, such as its rotational speed, intake air mass, coolant temperature, etc. The control unit 40 has an installation test module 42, which is configured to control the sequence of a method for installation testing of the secondary air system 30 and the exhaust aftertreatment component 28.

[0021] For installation testing of the secondary air system 30 and the exhaust aftertreatment component 28, a sensor device 50 is provided, which has three pressure sensors 52, 54, 56, wherein all pressure sensors 52, 54, 56 are connected in terms of signals to the control unit 40 or the installation test module 42. A first pressure sensor 52 is arranged on the secondary air system 30 and, in the flow direction of the air flow introduced by the secondary air pump 32, at a distance from the secondary air pump 32 and detects the air pressure prevailing in the secondary air system 30 between the secondary air pump 32 and the secondary air valves 34, 36, wherein the detected air pressure is transmitted to the control unit 40 or to the installation test module 42. A second pressure sensor 54 is arranged upstream of the exhaust aftertreatment component 28 in the flow direction of the air or exhaust gas during operation of the internal combustion engine 10 and detects the pressure upstream of the exhaust aftertreatment component 28. A third pressure sensor 56 is arranged downstream of the exhaust aftertreatment component 28 in the flow direction of the air or exhaust gas during operation of the internal combustion engine 10 and detects the pressure downstream of the exhaust aftertreatment component 28. The air pressures detected by the pressure sensors 54, 56 are transmitted to the control unit 40 or the installation test module 42. The pressure sensors 54, 56 can form a differential pressure sensor, wherein a pressure difference is transmitted to the installation test module 42.

[0022] During the installation test using the installation test module 42, the secondary air pump 32 of the secondary air system 30 is controlled in such a way that an air flow emanates from the secondary air pump 32 at an air pressure caused by the corresponding control of the secondary air pump 32. For the installation test of the secondary air system 30, the air pressure at a point spaced apart from the secondary air pump 32 in the direction of air flow is detected by the first pressure sensor 52 and transmitted to the installation test module 42. A pressure difference is determined from the air pressure provided by the control of the secondary air system 30 and the air pressure detected by the first pressure sensor 52, which in turn is compared with a first difference threshold value. If the determined pressure difference exceeds the first differential pressure threshold value, an installation error or a defect in the secondary air system 30, for example, the secondary air pump 32, is concluded.At the same time, the installation test module 42 performs an installation test of the exhaust aftertreatment component 28, with the air flow caused by the secondary air system 30 flowing via the exhaust system 20 to the exhaust aftertreatment component 28 and flowing through the exhaust aftertreatment component 28. The air pressure in the direction of air flow upstream and downstream of the exhaust aftertreatment component 28 is detected by the second and third pressure sensors 54, 56, transmitted to the installation test module 42, and a pressure difference between the two air pressures is determined in the installation test module 42. The determined pressure difference is then compared in the installation test module 42 with a second differential pressure threshold value stored in the installation test module 42. If the second differential pressure threshold value is exceeded, the determined pressure difference indicates an installation error, clogging, or similar in the exhaust aftertreatment component 28.The combustion engine 10 is inactive during the entire installation test.

Claims

[1] Method for testing the installation of an exhaust aftertreatment component (28) of an exhaust system (20) and a secondary air system (30) for an internal combustion engine (10), comprising the following steps: - Activation of the secondary air system (30), whereby air is pumped into the exhaust system (20) by a secondary air pump (32), - Installation test of the secondary air system (30), wherein an air pressure provided by the control of the secondary air pump (32) is compared with an air pressure present in the flow direction downstream of the secondary air pump (32), wherein if the pressure difference between the two air pressures exceeds a first difference threshold value, it is concluded that the secondary air system (30) is faulty, -Installation test of the exhaust gas aftertreatment component (28), wherein an air pressure in the flow direction upstream of the exhaust gas aftertreatment component (28) and an air pressure in the flow direction downstream of the exhaust gas aftertreatment component (28) are compared with one another, wherein if the pressure difference between the two air pressures exceeds a second difference threshold value, it is concluded that the exhaust gas aftertreatment component (28) is incorrectly installed, wherein the installation test of the secondary air system (30) and the exhaust gas aftertreatment component (28) is carried out with an inactive internal combustion engine (10). [2] Motor vehicle with an internal combustion engine (10), an exhaust system (20) having at least one exhaust aftertreatment component (28), a secondary air system (30) for introducing air into the exhaust system (20), a sensor device (50), and a control unit (40) having a shoring test module (42) designed to carry out the method according to claim 1. [3] Motor vehicle according to claim 2, characterized by that the exhaust gas aftertreatment component (28) is a particle filter (29). [4] Motor vehicle according to claim 2 or 3, characterized by that the sensor device (50) has a first pressure sensor (52) which is arranged in the flow direction of the air behind the secondary air pump (32) on the secondary air system (30). [5] Motor vehicle according to one of claims 2 to 4, characterized by in that the sensor device (50) has a second pressure sensor (54) and a third pressure sensor (56), wherein in the flow direction of the air flowing through the exhaust system (20), the second pressure sensor (54) is arranged upstream of the exhaust gas aftertreatment component (28) and the third pressure sensor (56) is arranged downstream of the exhaust gas aftertreatment component (28). [6] Motor vehicle according to claim 5, characterized by that the second and third pressure sensors (54, 56) form a differential pressure sensor.

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