Method for ascertaining an operating state of a burner

A method for ascertaining an operating state of an exhaust gas burner in an exhaust system of an internal combustion engine, wherein the burner is supplied with air by a secondary air system and with fuel by a fuel system, and wherein exhaust gas generated in the burner is discharged into the exhaust system of the internal combustion engine, the method comprising the following steps:

• detecting a sensor signal of at least one pressure sensor arranged in an air path upstream and/or downstream of the burner;
• ascertaining an amplitude of at least one periodic partial signal contained in the sensor signal and having a predeterminable frequency;
• ascertaining the operating state of the burner depending on the ascertained amplitude;
• and
• carrying out a measure depending on the ascertained operating state, wherein the measure includes:
• switching off the fuel system and/or switching off the secondary air system and/or blocking the internal combustion engine and/or activating an ignition of the burner when the operating state was ascertained as non-heating;
• wherein the predeterminable frequency of the at least one partial signal is equal to:
• (i) an injection frequency in the context of supplying fuel to the burner and/or (ii) a multiple of the injection frequency, and
• wherein the injection frequency of the burner and/or the multiple of the injection frequency is selected to be different from a rotation frequency of the internal combustion engine and a multiple of the rotation frequency.

A computing unit configured to ascertain an operating state of an exhaust gas burner in an exhaust system of an internal combustion engine, wherein the burner is supplied with air by a secondary air system and with fuel by a fuel system, and wherein exhaust gas generated in the burner is discharged into the exhaust system of the internal combustion engine, the computing unit configured to:

• detect a sensor signal of at least one pressure sensor arranged in an air path upstream and/or downstream of the burner;
• ascertain an amplitude of at least one periodic partial signal contained in the sensor signal and having a predeterminable frequency;
• ascertain the operating state of the burner depending on the ascertained amplitude;
• and
• carrying out a measure depending on the ascertained operating state, wherein the measure includes:
• switching off the fuel system and/or switching off the secondary air system and/or blocking the internal combustion engine and/or activating an ignition of the burner when the operating state was ascertained as non-heating;
• wherein the predeterminable frequency of the at least one partial signal is equal to:
• (i) an injection frequency in the context of supplying fuel to the burner and/or (ii) a multiple of the injection frequency, and
• wherein the injection frequency of the burner and/or the multiple of the injection frequency is selected to be different from a rotation frequency of the internal combustion engine and a multiple of the rotation frequency.

An exhaust system for an internal combustion engine, comprising:

• at least one burner configured to heat at least one component of the exhaust system, the at least one component being a catalyst;
• at least one pressure sensor in an air path upstream and/or downstream of the at least one burner;
• and
• a computing unit, wherein the at least one sensor is connected to the computing unit in a signal-conducting manner;
• wherein the computing unit is configured to:
• detect a sensor signal of the at least one pressure sensor arranged in the air path upstream and/or downstream of the at least one burner,
• ascertain an amplitude of at least one periodic partial signal contained in the sensor signal and having a predeterminable frequency,
• ascertain the operating state of the at least one burner depending on the ascertained amplitude;
• and
• carry out a measure depending on the ascertained operating state, wherein the measure includes:
• switching off the fuel system and/or switching off the secondary air system and/or blocking the internal combustion engine and/or activating an ignition of the at least one burner when the operating state was ascertained as non-heating;
• wherein the predeterminable frequency of the at least one partial signal is equal to:
• (i) an injection frequency in the context of supplying fuel to the at least one burner and/or (ii) a multiple of the injection frequency, and
• wherein the injection frequency of the at least one burner and/or the multiple of the injection frequency is selected to be different from a rotation frequency of the internal combustion engine and a multiple of the rotation frequency.

A non-transitory machine-readable storage medium on which is stored a computer program for ascertaining an operating state of an exhaust gas burner in an exhaust system of an internal combustion engine, wherein the burner is supplied with air by a secondary air system and with fuel by a fuel system, and wherein exhaust gas generated in the burner is discharged into the exhaust system of the internal combustion engine, the computer program, when executed by a computer, causing the computer to perform the following steps:

• detecting a sensor signal of at least one pressure sensor arranged in an air path upstream and/or downstream of the burner;
• ascertaining an amplitude of at least one periodic partial signal contained in the sensor signal and having a predeterminable frequency;
• and
• ascertaining the operating state of the burner depending on the ascertained amplitude;
• and
• carrying out a measure depending on the ascertained operating state, wherein the measure includes:
• switching off the fuel system and/or switching off the secondary air system and/or blocking the internal combustion engine and/or activating an ignition of the burner when the operating state was ascertained as non-heating;
• wherein the predeterminable frequency of the at least one partial signal is equal to:
• (i) an injection frequency in the context of supplying fuel to the burner and/or (ii) a multiple of the injection frequency, and
• wherein the injection frequency of the burner and/or the multiple of the injection frequency is selected to be different from a rotation frequency of the internal combustion engine and a multiple of the rotation frequency.