Exhaust system for a motor vehicle, method for operating the same, motor vehicle

Abstract

An exhaust system (1) for a motor vehicle (100) is provided, wherein the exhaust system (1) has an exhaust gas burner (2), wherein the exhaust system (1) has a pressure sensor (3) for sensing a flame formation in the exhaust gas burner (2). A method and a motor vehicle (100) are also proposed.

Description

TECHNICAL FIELD

[0001] The present invention relates to an exhaust system for a motor vehicle, a method for operating an exhaust system and a motor vehicle. BACKGROUND

[0002] In order to meet the increasing requirements for environmental friendliness of motor vehicles comprising internal combustion engines, the treatment of the exhaust gases of the internal combustion engines in the exhaust system is becoming more and more complex. Modern motor vehicles have complex exhaust systems, the individual components of which make an efficient contribution to optimizing the performance of the motor vehicle and purifying the exhaust gases.

[0003] Particularly high demands are placed on exhaust gas purification components, such as catalytic converters or particulate filters. In order to meet these demands, the boundary conditions under which the exhaust gas purification components are operated must be correct. The efficiency of catalytic converters, for example, depends on their temperature. In particular when the motor vehicle is started from cold, the temperature of the catalytic converter is usually below the so-called light-off temperature from which the catalytic converter works with high efficiency. Other exhaust gas purification components, in particular particulate filters, must be brought to a regeneration temperature from time to time in order to clean the soot particles deposited there.

[0004] In order to quickly and purposefully achieve these high temperatures, the exhaust system usually has an exhaust gas burner. A fuel-air mixture is ignited in the exhaust gas burner and the hot exhaust gases from the combustion of the fuel-air mixture are guided to the point to be heated, for example a catalytic converter or a particulate filter.

[0005] For this purpose, combustion air is usually supplied to the exhaust gas burner by means of a blast section, while fuel is supplied by means of a fuel line. The combustion air and the fuel are mixed in a combustion chamber and ignited with an igniter. In order to ensure the proper functioning of the exhaust system, it is important to monitor the ignition, i.e. the formation of a flame, in the exhaust gas burner. Temperature sensors are usually slow to react. Furthermore, for a temperature sensor, the arrangement position of the temperature sensor on the exhaust gas burner is crucial in order to draw precise conclusions about the flame formation. SUMMARY

[0006] It is an object of the present invention to provide an exhaust system which does not have the above-mentioned disadvantages of the prior art, but enables a robust and precise sensing of the flame formation in the exhaust gas burner.

[0007] The solution according to the invention to achieve the above-mentioned object is an exhaust system for a motor vehicle, wherein the exhaust system has an exhaust gas burner, wherein the exhaust system has a pressure sensor for sensing the flame formation in the exhaust gas burner.

[0008] The exhaust system according to the application precisely and unambiguously senses the flame formation by means of the pressure change at the moment of flame formation in the exhaust gas burner. In contrast to a temperature sensor, no time delay occurs when the flame formation is detected by means of the pressure sensor due to the delayed temperature increase of the temperature sensor. Furthermore, the significance of the arrangement of the pressure sensor is significantly reduced, so that the pressure sensor can also be arranged further away from the combustion chamber of the exhaust gas burner and is thus well protected from the heat generated by the combustion.

[0009] The advantageous technical solution and further solutions of the application are described with reference to the drawings.

[0010] According to a preferred embodiment of the application, the exhaust system has an air supply section for introducing combustion air into the exhaust gas burner, wherein the pressure sensor is arranged in the air supply section and in particular outside the combustion chamber of the exhaust gas burner. By this, the available construction space is optimally utilized and the pressure sensor is protected from excessive heat.

[0011] According to a further preferred embodiment of the application, the exhaust system has a further pressure sensor, wherein the further pressure sensor is arranged in the exhaust section of the exhaust gas burner, wherein the pressure sensor and the further pressure sensor are configured to determine the pressure difference between the air supply section and the exhaust section. By determining the pressure upstream of the exhaust gas burner and determining the pressure downstream of the exhaust gas burner, the flame formation can be inferred very precisely by means of the pressure difference.

[0012] According to a further preferred embodiment of the application, the exhaust system has an optical sensor arranged in the exhaust gas burner, preferably in the combustion chamber. This advantageously enables an optical check of the flame formation sensing.

[0013] According to a further preferred embodiment of the application, the air supply section has an air pump for delivering air into the exhaust gas burner, wherein the pressure sensor is arranged between the air pump and the exhaust gas burner, wherein the pressure sensor is preferably arranged between the air pump and a valve of the air supply section. This advantageously ensures that the pressure sensor can detect the pressure change caused by the flame formation. The air pump is preferably adjustable, so that more or less air can be delivered into the exhaust gas burner. The valve is preferably a non-return valve, which prevents the fuel-air mixture from the exhaust gas burner from entering the air supply section. The air supply section preferably has an air filter.

[0014] According to a further preferred embodiment of the application, the pressure sensor is designed as a dual sensor for detecting pressure and temperature. This makes it possible to measure the temperature of the air introduced into the exhaust gas burner in an advantageous manner.

[0015] To this end, preferably, the exhaust system has a temperature sensor for sensing the exhaust gas temperature of the exhaust gas burner. In this way, the temperature difference between the air flowing into the exhaust gas burner and the exhaust gas flowing out of the exhaust gas burner can advantageously be measured, and in turn the flame formation sensing by the pressure sensor can be checked.

[0016] A further solution of the application to achieve the objects set out in the opening part is a method for operating an exhaust system of a motor vehicle, wherein the flame formation in an exhaust gas burner of the exhaust system is sensed by means of a pressure sensor.

[0017] By means of the method of the application, the formation of a flame in the exhaust gas burner can be sensed precisely. Unlike in the sensing by means of temperature change, no time delay occurs due to the delayed temperature increase of the temperature sensor when the flame formation is recognized in the method of the application. Furthermore, the position criticality of the pressure sensing is much lower compared to the case of temperature-based sensing using temperature sensors known from the prior art.

[0018] According to a further preferred embodiment of the application, the air pressure in the air supply section for introducing combustion air into the exhaust gas burner is sensed by means of the pressure sensor. This ensures that the pressure sensor is well protected from excessive heat on the exhaust gas burner.

[0019] According to a further preferred embodiment of the application, the flame formation is sensed on the basis of the pressure difference between the air supply section and the exhaust section of the exhaust gas burner. By this, a further extremely precise way of determining the flame formation is achieved.

[0020] According to a further preferred embodiment of the application, the formation of a flame is additionally sensed:

[0021] - optically in the combustion chamber of the exhaust gas burner, and / or

[0022] - by means of the temperature difference between the air flowing into the exhaust gas burner and the exhaust gas flowing out of the exhaust gas burner, and / or

[0023] - acoustically by means of a knock sensor of the motor vehicle.

[0024] By this, the pressure-based flame formation sensing can advantageously be well checked. In particular, the use of a knock sensor proves to be advantageous, since it is usually present in the motor vehicle and thus no further components have to be used.

[0025] According to a further preferred embodiment of the application, an exhaust system according to the application is used.

[0026] A further solution of the application to achieve the objects set out in the opening part is a motor vehicle having an exhaust system of the application.

[0027] All details, features and advantages disclosed in connection with the exhaust system of the present application apply equally to the motor vehicle of the present application and to the method of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0028] Further details, features and advantages of the present application are described below with reference to the drawings and to the description of preferred embodiments in connection with the drawings. The drawings show only exemplary embodiments of the present application and do not limit the inventive concept.

[0029] Figure 1 An exhaust system according to an exemplary embodiment of the present application is schematically shown.

[0030] Figure 2 A motor vehicle according to an exemplary embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0031] Figure 1 An exhaust system 1 according to an exemplary embodiment of the present application is schematically shown. The exhaust system 1 conducts exhaust gases of an internal combustion engine 13 of a motor vehicle and purifies them in a first catalytic converter 14, a second catalytic converter 15 and a particulate filter 16.

[0032] In order to quickly and precisely bring the second catalytic converter 15 and the particulate filter 16 to a certain temperature, for example after a cold start, the exhaust system 1 has an exhaust gas burner 2. Fuel or combustion air is introduced into a combustion chamber 5 of the exhaust gas burner 2 via a fuel line 17 and a supply air section 4. The mixture of combustion air and fuel is then ignited and burned in the combustion chamber 5. The hot exhaust gases generated in this case are conducted to the second catalytic converter 15 and the particulate filter 16 via an exhaust section 6 and heat them up.

[0033] In order to precisely regulate the exhaust system 1, it is crucial to monitor the combustion in the exhaust gas burner 2, in particular the flame formation. For this purpose, the exhaust system 1 has a pressure sensor 3. The pressure sensor 3 is arranged in the supply air section 4 and is spaced a certain distance from the exhaust gas burner 2, so that the pressure sensor 3 is protected from the heat generated in the combustion chamber 5. If the mixture of combustion air and fuel ignites in the combustion chamber 5 and a flame is formed in the process, a change in pressure can be detected by the pressure sensor 3.

[0034] In addition to the pressure sensor 3, the supply air section 4 has an air filter 12 for purifying the combustion air, an air pump 8 for generating an air flow to the exhaust gas burner 2 and a valve 9. The pressure sensor 3 is arranged between the air pump 8 and the valve 9, which is designed as a non-return valve. In this way, the pressure sensor 3 can detect the pressure change caused by the flame formation.

[0035] A further pressure sensor 3' is provided in the exhaust section 6 of the exhaust gas burner 2. It is thus possible to determine the pressure difference across the exhaust gas burner 2 together with the pressure sensor 3. This also makes it possible to sense the flame formation in the combustion chamber 5 extremely precisely.

[0036] Furthermore, the exhaust section 6 has a temperature sensor 10 for measuring the exhaust gas temperature of the exhaust gas burner 2. The pressure sensor 3 is preferably designed as a dual sensor for determining the pressure and the temperature. It is thus also possible to deduce the flame formation with the pressure sensor 3 and the temperature sensor 10 by determining the temperature in the supply section 4 and the exhaust gas temperature of the exhaust gas burner 2 and to check the pressure-based flame formation sensing thereby. In order to check the pressure-based flame formation sensing, the exhaust gas burner 2 also has an optical sensor 7 in the combustion chamber 5. It is also possible to deduce the flame formation acoustically from the knocking sensor of the motor vehicle (see Figure 2 ).

[0037] Figure 2 A motor vehicle 100 according to an exemplary embodiment of the application is shown schematically. The motor vehicle 100 has an internal combustion engine 13 and an exhaust system 1 according to an exemplary embodiment of the application. The flame formation sensing in the exhaust gas combustion chamber of the exhaust system 1 is checked acoustically by means of a knocking sensor 11.

[0038] List of reference signs

[0039] 1 exhaust system

[0040] 2 exhaust gas burner

[0041] 3 pressure sensor

[0042] 3' further pressure sensor

[0043] 4 supply section

[0044] 5 combustion chamber

[0045] 6 exhaust section

[0046] 7 optical sensor

[0047] 8 air pump

[0048] 9 valve

[0049] 10 temperature sensor

[0050] 11 knocking sensor

[0051] 12 air filter

[0052] 13 internal combustion engine

[0053] 14 first catalytic converter

[0054] 15 second catalytic converter

[0055] 16 particulate filter

[0056] 17 fuel line

[0057] 100 motor vehicle

Claims

1. An exhaust system (1) for a motor vehicle (100), wherein the exhaust system (1) has an exhaust combustor (2), characterized in that, The exhaust system (1) has a pressure sensor (3) for sensing flame formation in the exhaust combustor (2), the exhaust system (1) has an air supply section (4) for introducing combustion air into the exhaust combustor (2), wherein the pressure sensor (3) is arranged in the air supply section (4) and outside the combustion chamber (5) of the exhaust combustor (2), the exhaust system (1) has another pressure sensor (3'), wherein the other pressure sensor (3') is arranged in the exhaust section (6) of the exhaust combustor (2), wherein the pressure sensor (3) and the other pressure sensor (3') are configured to measure the pressure difference between the air supply section (4) and the exhaust section (6), wherein the hot exhaust gas generated in the combustion chamber (5) of the exhaust combustor (2) is guided through the exhaust section (6), and wherein the other pressure sensor (3') is arranged upstream of the intersection of the exhaust section of the internal combustion engine (13) of the exhaust system (1) and the exhaust section (6).

2. The exhaust system (1) according to claim 1, characterized in that, The exhaust system (1) has an optical sensor (7) arranged in the exhaust gas burner (2).

3. The exhaust system (1) according to claim 2, characterized in that, The exhaust system (1) has an optical sensor (7) arranged in the combustion chamber (5).

4. The exhaust system (1) according to any one of claims 1 to 3, characterized in that, The air supply section (4) has an air pump (8) for supplying air to the exhaust gas burner (2), wherein the pressure sensor (3) is arranged between the air pump (8) and the exhaust gas burner (2).

5. The exhaust system (1) according to claim 4, characterized in that, The pressure sensor (3) is located between the air pump (8) and the valve (9) of the air supply section (4).

6. The exhaust system (1) according to any one of claims 1 to 3, characterized in that, The pressure sensor (3) is designed as a dual sensor for sensing pressure and temperature.

7. The exhaust system (1) according to claim 6, characterized in that, The exhaust system (1) has a temperature sensor (10) for sensing the exhaust gas temperature of the exhaust gas burner (2).

8. A method for operating the exhaust system (1) of a motor vehicle (100), characterized in that, Flame formation in the exhaust combustor (2) of the exhaust system (1) is sensed by means of a pressure sensor (3); the air pressure in the air supply section (4) for introducing combustion air into the exhaust combustor (2) is sensed by the pressure sensor (3), and another pressure sensor (3') is arranged in the exhaust section (6) of the exhaust combustor (2), wherein the hot exhaust gas generated by the combustion chamber (5) of the exhaust combustor (2) is guided through the exhaust section (6); flame formation is sensed based on the pressure difference between the air supply section (4) and the exhaust section (6) of the exhaust combustor (2), wherein the other pressure sensor (3') is arranged upstream of the intersection of the exhaust section of the internal combustion engine (13) of the exhaust system (1) and the exhaust section (6).

9. The method according to claim 8, characterized in that, Additional -In the combustion chamber (5) of the exhaust gas burner (2) in an optical manner, and / or -By the temperature difference between the air flowing into the exhaust gas burner (2) and the exhaust gas flowing out of the exhaust gas burner (2), and / or - The formation of flames is sensed acoustically by the knock sensor (11) of the motor vehicle (100).

10. The method according to claim 8 or 9, characterized in that, The method is performed using the exhaust system (1) according to any one of claims 1 to 7.

11. A motor vehicle (100) having an exhaust system (1) according to any one of claims 1 to 7.

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