Method for monitoring a burner and a device therefor

Abstract

The invention relates to a method for monitoring a burner (5) in the exhaust system (3) of a motor vehicle (1), in which combustion media (6, 7) are admitted into a combustion chamber (8) and subsequently ignited by means of an ignition device (10), wherein the hot combustion gases produced during combustion are discharged from the burner (5) for exhaust gas purification of an internal combustion engine (2), wherein at least one acoustic sensor (11) is provided which detects the combustion noises. The invention also relates to a device for this purpose.

Description

[0001] The invention relates to a method for monitoring a burner, in particular a burner intended for exhaust gas purification in the exhaust duct of an internal combustion engine. The invention also relates to a device for this purpose.

[0002] Such burners are known from DE 42 15 134 A1. Methods for monitoring such burners are known from DE 10 2010 027 987 A1.

[0003] To comply with increasingly stringent emission limits for vehicles with internal combustion engines, cold-start emissions must be further reduced. For this purpose, burners, also known as exhaust gas burners, will be used in the future. The exhaust gas purification burner serves to quickly heat the catalyst to pollutant conversion temperature through the combustion of air and fuel in the exhaust system of the internal combustion engine, resulting in a more accelerated reduction in emissions than would occur without a burner. Stable ignition and combustion are essential, as otherwise, compliance with emission limits cannot be guaranteed.

[0004] DE 10 2010 013 011 A1 uses a temperature sensor to monitor the temperature of the combustion gases, with the fuel supply being controlled depending on the measured temperature. The temperature of the exhaust gas at a particular point in the burner can only ever be an integral measurement, which, moreover, only results after a time delay after combustion. Dedicated monitoring of the ignition and thus also of the combustion process is not possible with this method.

[0005] In DE 10 2010 027 987 A1, the fuel and air supply are monitored to diagnose the burner. This method uses fuel and air pressure values ​​in the lines before combustion to determine the combustion itself. Dedicated monitoring of the ignition and thus also of the combustion process is also not possible.

[0006] DE 101 25 588 C1 describes an auxiliary heater that has a fuel supply to the burner and a control unit that regulates the heater's operation. To reduce pollutant emissions and fuel consumption, the control unit is designed to receive a signal that provides information about the quality of the supplied fuel and adjusts the auxiliary heater's operation accordingly.

[0007] DE 199 45 562 A1 describes a method for monitoring and regulating the fan speed of a heater, in particular a fuel-powered water or air heater in motor vehicles, a combustion chamber, and a fan for supplying combustion air. It is proposed to monitor the flame in the combustion chamber and / or the fan speed using a pressure or sound pressure sensor. The monitored signal can then be used or further processed to control or regulate the fan speed of the heater.

[0008] The object of the present invention is therefore to provide a method for monitoring a burner that directly monitors the ignition itself in order to achieve better controllability of the ignition and thus also of the combustion. It is also the object to provide a device for implementing the method that allows reliable monitoring of the burner.

[0009] This object of the method is achieved with the features of claim 1.

[0010] One embodiment of the invention relates to a method for monitoring a burner in the exhaust system of a motor vehicle, in which combustion media are admitted into a combustion chamber and subsequently ignited by means of an ignition device, wherein the hot combustion gases produced during combustion are discharged from the burner for exhaust gas purification of an internal combustion engine, wherein at least one acoustic sensor is provided which detects the combustion noise. By monitoring the ignition noise, the ignition of the combustion media itself and thus also the actual combustion can be monitored. Since at least the fuel, as one of the combustion media, is injected in pulsed form by a pump, a pulsed ignition noise also results, which is easily monitored acoustically.

[0011] A control unit is also provided, which receives and further processes the signals from the acoustic sensor to control the ignition of the burner and / or the supply of at least one combustion medium or media. Thus, the acoustic noise is evaluated directly in the provided control unit, allowing for quick and immediate control.

[0012] It is planned that the acoustic sensor signals will be filtered, particularly by bandpass filtering, as a further processing step. This will prevent errors that would otherwise result from parasitic noise.

[0013] It is further provided that the acoustic sensor signals are filtered at least twice in parallel, with each filtering step being performed using a filter with a different center frequency, such as a bandpass filter. This means that the signals are used twice in parallel to evaluate and compare them to obtain a result.

[0014] It is also planned that the further processed and / or filtered signals will be evaluated in relation to the volume of the acoustic signal. This will allow an acoustic parameter resulting from the previous processing to be used for evaluation. This way, sources of error can be eliminated as far as possible or their impact can be reduced.

[0015] It is also provided that the respective volume of the two acoustic signals are compared with each other and from this a signal is determined for controlling the ignition of the burner and / or the supply of at least one combustion medium or combustion media.

[0016] It is advisable to use fuel and air as combustion media. These are readily available in the motor vehicle and thus essentially produce the same combustion exhaust gases as the exhaust gases of the internal combustion engine.

[0017] It is also advantageous if a pulse detection of the acoustic signal is carried out, whereby after a bandpass filtering an edge detection is carried out, from which a pulse width determination is carried out.

[0018] It is particularly advantageous if the acoustic sensor is a knock sensor. Since the knock sensor is a structure-borne sound sensor, it can accurately detect the acoustic effects of combustion.

[0019] This object of the device is achieved with the features of claim 5.

[0020] An embodiment of the invention relates to a device for carrying out a method according to at least one of the preceding claims, with a burner in the exhaust system of a motor vehicle, in which combustion media can be admitted into a combustion chamber and ignited by means of an ignition device, wherein the hot combustion gases produced during combustion can be discharged from the burner for exhaust gas purification of an internal combustion engine and wherein at least one acoustic sensor is provided which detects the combustion noises, wherein a control unit is also provided which receives the signals from the acoustic sensor and further processes them to control the ignition of the burner and / or the supply of at least one combustion medium or the combustion media.

[0021] The invention is explained in detail below using an exemplary embodiment with reference to the drawing. The drawing shows: Fig. 1 a schematic representation of a motor vehicle with a device according to the invention.

[0022] The Fig. 1 shows a motor vehicle 1 with an internal combustion engine 2 and an exhaust system 3 with a catalytic converter 4.

[0023] Furthermore, a device is provided which comprises a burner 5, by means of which fuel 6 and air 7 can be burned to heat exhaust gases of the internal combustion engine 2 and to quickly heat the catalyst 4. The fuel 6 and the air 7 are typical combustion media of the burner.

[0024] The burner 5 is arranged in the exhaust system 3 of the motor vehicle 1. The burner 5 is designed such that it has a combustion chamber 8 into which the combustion media, fuel 6 and air 7, are admitted and ignited to burn. The hot combustion gas from the combustion in the combustion chamber 8 is discharged via line 9 into the exhaust system 3 for exhaust gas purification of an internal combustion engine and for heating the catalytic converter 4.

[0025] In the combustion chamber 8, an ignition device 10 is provided for igniting the combustion of the combustion media 6, 7.

[0026] Furthermore, at least one acoustic sensor 11 is provided which detects the combustion noises, wherein a control unit 12 is also provided which receives the signals of the acoustic sensor 11 and further processes them to control the ignition of the burner 5 and / or the supply of at least one combustion medium 6, 7 or the combustion media 6, 7.

[0027] Further processing can include, for example, filtering, such as bandpass filtering, of the signals from acoustic sensor 11. For example, the signals from acoustic sensor 11 can be filtered at least twice in parallel, with each filtering step being performed using a filter with a different center frequency of the respective filter, such as a bandpass filter. This generates two differently filtered signals, which can then be further evaluated and, for example, compared.

[0028] The further processed and / or filtered signals can also be evaluated, for example, with respect to the volume of the acoustic signal. For example, the respective volume of the two acoustic signals can be compared, and from this, a signal for controlling the ignition of the burner 5 and / or the supply of at least one combustion medium 6, 7 or the combustion media 6, 7 can be determined.

[0029] For example, pulse detection of the acoustic signal can be performed. After bandpass filtering, edge detection is performed, from which a pulse width can be determined. This allows conclusions to be drawn about the ignition status from the detected pulses or the detected pulse width.

[0030] In particular, the acoustic sensor 11 is a knock sensor, i.e. a structure-borne sound sensor. List of reference symbols 1 motor vehicle 2 combustion engine 3 Exhaust system 4 Catalyst 5 burners 6 Fuel 7 Air 8 combustion chamber 9 Management 10 Ignition device 11 acoustic sensor 12 Control unit

Claims

[1] Method for monitoring a burner (5) in the exhaust system (3) of a motor vehicle (1), in which combustion media (6, 7) are admitted into a combustion chamber (8) and subsequently ignited by means of an ignition device (10), wherein the hot combustion gases produced during combustion are discharged from the burner (5) for the purpose of purifying the exhaust gases of an internal combustion engine (2), characterized bythat at least one acoustic sensor (11) is provided which detects the combustion noises, wherein a control unit (12) is further provided which receives the signals of the acoustic sensor (11) and further processes them to control the ignition of the burner (5) and / or the supply of at least one combustion medium (6, 7) or the combustion media (6, 7), wherein as further processing, a filtering, such as in particular bandpass filtering, of the signals of the acoustic sensor (11) takes place, wherein the signals of the acoustic sensor (11) are filtered at least twice in parallel, wherein the respective filtering takes place with a filter with a different center frequency of the respective filter, such as in particular a bandpass filter, wherein the further processed and / or filtered signals are evaluated with regard to the volume of the acoustic signal,wherein the respective volume of the two acoustic signals is compared with each other and a signal for controlling the ignition of the burner (5) and / or the supply of at least one combustion medium (6,7) or the combustion media (6,7) is determined therefrom. [2] Method according to claim 1, characterized by that fuel (6) and air (7) are used as combustion media. [3] Method according to claim 1 or 2, characterized by that a pulse detection of the acoustic signal is carried out, whereby after a bandpass filtering an edge detection is carried out, from which a pulse width determination is carried out. [4] Method according to one of the preceding claims, characterized by that the acoustic sensor (11) is a knock sensor. [5] Device for carrying out a method according to at least one of the preceding claims, with a burner (5) in the exhaust system (3) of a motor vehicle (1), in which combustion media (6, 7) can be admitted into a combustion chamber (8) and ignited by means of an ignition device (10), wherein the hot combustion gases produced during combustion can be discharged from the burner (5) for the purpose of cleaning the exhaust gases of an internal combustion engine (2), and wherein at least one acoustic sensor (11) is provided which detects the combustion noises, wherein a control unit (12) is also provided which receives the signals from the acoustic sensor (11) and further processes them to control the ignition of the burner (5) and / or the supply of at least one combustion medium (6, 7) or the combustion media (6, 7).

Images