# US 8,788,184 B2 · Method and apparatus for the self-diagnosis of an exhaust gas probe > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,788,184 B2 - Document ID: US8788184B2 - Status: Granted - Kind: B2 - Application number: 13/089,770 - Filed: 2011-04-19 - Published: 2011-10-20 - Granted: 2014-07-22 - Earliest claimed: 2010-04-20 - Assignees: Robert Bosch GmbH - Applicants: Thomas Baumann; Enno Baars; Johannes Grabis; Benjamin Hagemann; Bernhard Kamp - Inventors: Thomas Baumann; Enno Baars; Johannes Grabis; Benjamin Hagemann; Bernhard Kamp - Web page: https://patentgrep.com/patent/US8788184B2 ## CPC - F01N 11/00: Monitoring or diagnostic devices for exhaust-gas treatment apparatus - F01N 2560/00: Exhaust systems with means for detecting or measuring exhaust gas components or characteristics - F01N 2560/20: Sensor having heating means - Y02T 10/40: Engine management systems - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method for the self-diagnosis of an exhaust gas probe (20). The exhaust gas probe (20) has at least one heating element (26). The method includes a modeled heat output PH is determined for the heating element (26) by means of a computer program comparing parameters of the gas stream with a measured heat output, and determining, when the parameters of the gas stream exceeds the measured heat output by more than a defined tolerance limit, that one of the exhaust gas probe (20) is defective, and an exhaust gas section (17) in which the exhaust gas probe (20) is installed is faulty. ## Claims ### Claim 1 An apparatus for the self-diagnosis of an exhaust gas probe (20), the exhaust gas probe (20) having at least one heating element (26) and the exhaust gas probe (20) being connected to a controller, and the controller having devices for the diagnosis of the exhaust gas probe (20), characterized in that the controller has at least one calculating unit for the determination, in a modeled manner, of a parameter which denotes the correct operation of the exhaust gas probe (20), this parameter determined from parameters of the gas stream, and comparing said parameter with a measured parameter by means of at least one evaluation unit which is integrated into the controller, and determining the exhaust gas probe (20) is defective when a deviation exceeds a defined tolerance limit, or determining a faulty condition exists in an exhaust gas section (17), in which the exhaust gas probe (20) is installed. ### Claim 2 (depends on 1) An apparatus according to claim 1, characterized in that the parameter which is defined in a modeled manner, is compared with the measured parameter is the heat output PH of the heating element (26) of the exhaust gas probe (20). ### Claim 3 (depends on 2) An apparatus according to claim 2, characterized in that the exhaust gas probe (20) is configured as a particle sensor for determining a soot loading in the gas stream. ### Claim 4 (depends on 1) An apparatus according to claim 1, characterized in that the controller is one of an engine controller (14) of an internal combustion engine (10) or a sensor control unit. ### Claim 5 (depends on 1) An apparatus according to claim 1, characterized in that the parameter which denotes correct operation of the exhaust gas probe (20) is determined from boundary conditions of the gas stream or from measured parameters of the gas stream. ### Claim 6 A method for the self-diagnosis of an exhaust gas probe (20), the exhaust gas probe (20) having at least one heating element (26), characterized in that a modeled heat output PH is determined for the heating element (26) by means of a computer program comparing parameters of the gas stream with a measured heat output, and determining, when the parameters of the gas stream exceeds the measured heat output by more than a defined tolerance limit, that one of the exhaust gas probe (20) is defective, and an exhaust gas section (17) in which the exhaust gas probe (20) is installed is faulty. ### Claim 7 (depends on 6) A method according to claim 6, characterized by determining the measured heat output PH from a heating current IH and a heating voltage UH applied to the heating element (26). ### Claim 8 (depends on 7) A method according to claim 7, characterized by using the heating voltage UH as a replacement variable. ### Claim 9 (depends on 7) A method according to claim 7, characterized by determining a heat output from an available supply voltage UBat and a maximum possible heating duty factor TVmax, and using the heat output as replacement variable. ### Claim 10 (depends on 6) A method according to claim 6, characterized by detecting, by a temperature measuring device in the exhaust gas probe (20), whether a setpoint temperature has been reached, and determining whether a deviation has been caused as a consequence of unfavorable operating conditions. ### Claim 11 (depends on 6) A method according to claim 6, characterized by determining additional variables beyond the heat output PH determined in a modeled manner, and using the determined additional variables for a comparison. ### Claim 12 (depends on 6) A method according to claim 6, characterized by subjecting input variables for the measured parameters for the gas stream to a filtering operation, and subsequently processing the input variables further to determine the modeled heat output. ### Claim 13 (depends on 6) A method according to claim 6, characterized by comparing temporal changes of the variables which are determined in a modeled manner with the measured variables or their changes. ### Claim 14 (depends on 6) A method according to claim 6, characterized by comparing an observed change in the heat output with a change in the parameters of the gas stream, and comparing a ratio of the change in the heat output and a change in the parameters of the gas stream with a threshold value. ### Claim 15 (depends on 14) A method according to claim 14, characterized in that the threshold is predefined or is variable based on a function of the parameters or the parameters which define the gas stream. ### Claim 16 (depends on 6) A method according to claim 6, characterized by determining a particle content in the gas stream using, as the exhaust gas probe (20), a particle sensor, and heating the particle sensor by means of the heating element (26) in a regeneration phase to remove a soot loading on the particle sensor. ### Claim 17 (depends on 6) A method according to claim 6, characterized in that the diagnosis is carried out during a phase having a constantly controlled temperature, or during a regeneration of the exhaust gas probe (20) having a heating ramp for achieving a free burning temperature required for soot elimination, or when the measured actual temperature deviates from an expected temperature setpoint value. ### Claim 18 (depends on 6) A method according to claim 6, characterized by determining the parameters of the gas stream from boundary conditions of the gas stream or from measured parameters of the gas stream. ### Claim 19 (depends on 6) A method according to claim 6, characterized in that the measured heat output PH is determined from a replacement variable. ### Claim 20 A method for the self-diagnosis of an exhaust gas probe (20), the exhaust gas probe (20) having at least one heating element (26), characterized in that a modeled parameter is determined for the heating element (26) by means of a computer program comparing parameters of the gas stream with the modeled parameter, and determining, when the parameters of the gas stream exceeds the modeled parameter by more than a defined tolerance limit, that one of the exhaust gas probe (20) is defective, and an exhaust gas section (17) in which the exhaust gas probe (20) is installed is faulty.