114 results about "Nitrogen oxide sensor" patented technology

The invention provides a method for rapidly detecting the content of nitrogen oxides in air. The method comprises the following steps: acquiring original signal data of nitrogen oxides in air in a target detection area in real time through a plurality of nitrogen oxide sensors; performing noise reduction filtering processing on the original signal data to generate target signal data; performing signal drift compensation correction on the target signal data based on a preset sensor calibration model to generate standardized concentration data; performing space-time correlation analysis on the standardized concentration data through a nitrogen oxide concentration prediction algorithm model in combination with environment parameter data collected in real time to generate a target prediction concentration value; and comparing the target predicted concentration value with a preset concentration standard threshold value based on a fuzzy logic judgment algorithm, and constructing a detection report. The whole process from data acquisition to report generation is intelligent, and the detection flexibility is remarkably improved.

A system, method, and apparatus for detecting sensor tampering are provided. An aftertreatment system includes a first train having a first selective catalytic reduction (SCR) system, a first doser, and a first NOx sensor; a second train having a second SCR system, a second doser, and a second NOx sensor; and a controller. The controller determines satisfaction of activation conditions. The controller doses reductant to the first and second SCR systems. The controller determines the NOx levels of the first SCR system and the second SCR system. The controller adjusts the dosing of the first SCR system for a period of time. The controller measures the NOx levels of the first SCR system and the second SCR system. The controller determines a difference between the third and first NOx levels and a difference between the fourth and second NOx levels.The control generates an indication as to whether the first NOx sensor is displaced.

The invention discloses a self-correction method for carbon deposition of a nitrogen-oxygen sensor, relates to the technical field of motor vehicle exhaust emission monitoring, and solves the problems that an existing solution for carbon deposition of the nitrogen-oxygen sensor causes irreversible damage to the nitrogen-oxygen sensor and the compensation error limitation is small. The method comprises the following steps: acquiring driving parameters and real-time NOx concentration of a vehicle, inputting the driving parameters into a constructed driving parameter-NOx concentration related neural network model to obtain predicted NOx concentration, obtaining a difference between the real-time NOx concentration and the predicted NOx concentration to obtain a NOx concentration deviation value, and calculating the NOx concentration deviation value according to the calculated NOx concentration deviation value. And a NOx concentration correction strategy is triggered according to the NOx concentration deviation value to obtain a NOx concentration correction value, and when preset engine parameter conditions are met, the fuel injection quantity is controlled according to the NOx concentration correction value. The phenomenon of insufficient combustion of the engine is reduced, the carbon deposition generation rate is reduced, and the requirement for frequent disassembly and cleaning of the sensor due to carbon deposition failure is avoided.

The invention discloses a nitrogen oxide sensor verification method and device and an engine. Whether a nitrogen oxide sensor has an untrusted fault or not can be judged in time. The nitrogen oxide sensor verification method comprises the following steps: when an oxygen concentration value measured by a target nitrogen oxide sensor is abnormal and oxygen concentration values measured by other nitrogen oxide sensors are normal, triggering a mutual verification mechanism; based on the mutual verification mechanism, calculating an oxygen concentration average value of the target nitrogen oxide sensor and all oxygen concentration average values of all nitrogen oxide sensors; when the absolute value of the difference value between the average oxygen concentration value and the average value of all the oxygen concentrations is larger than a preset threshold value, prompt information about the untrusted fault of the target nitrogen oxide sensor is sent out.

The application discloses a nitrogen oxide sensor signal detection method and device and a nitrogen oxide sensor. The method comprises the following steps: obtaining a plurality of first nitrogen oxide concentrations and a plurality of second nitrogen oxide concentrations after determining that an engine is started, wherein the first nitrogen oxide concentration is simulated by a nitrogen oxide signal simulator based on an adjusted nitrogen oxide signal, the second nitrogen oxide concentration is calculated by an electronic controller of the engine, and the nitrogen oxide sensor is used for detecting the concentration of nitrogen oxide in exhaust gas emitted by the engine; determining a correlation value and a characteristic value of the plurality of first nitrogen oxide concentrations and the plurality of second nitrogen oxide concentrations; and determining whether the nitrogen oxide signal sent by the nitrogen oxide sensor to the engine is abnormal based on the correlation value and the characteristic value. The application solves the technical problem that the related art cannot effectively determine whether the NOx sensor signal is tampered with, thereby reducing the reliability of the engine.

The application belongs to the field of automobile exhaust aftertreatment, and particularly relates to a two-dimensional calibration method for output results of a nitrogen oxide sensor, comprising the following steps: constructing a ratio table between accurate nitrogen oxide concentration values and corresponding nitrogen oxide concentration test values under different oxygen concentration and nitrogen oxide concentration environments, taking the oxygen concentration and the nitrogen oxide concentration test values as indexes of oxygen concentration and nitrogen oxide concentration in the ratio table respectively, determining the ratio, and correcting the nitrogen oxide concentration test values; constructing a ratio table between accurate oxygen concentration values and corresponding oxygen concentration test values under different second chamber pump currents Ip1 and different oxygen concentration environments, taking the current Ip1 corresponding to the oxygen concentration test value and the oxygen concentration test value as indexes of Ip1 and oxygen concentration in the ratio table respectively, determining the ratio, and correcting the oxygen concentration test values; and finally setting a control target parameter of Ip1 in dynamic control of the nitrogen oxide sensor, and applying the ratio table to the output of the nitrogen oxide sensor. The application can improve the measurement accuracy of the sensor and accelerate dynamic response tracking.

The present invention discloses an industrial furnace flue gas denitrification and heat recovery device, which relates to the field of flue gas treatment technology and includes a denitrification reactor, an air preheater, a multi-stage catalyst, a soot blowing mechanism, an ammonia generator, a reflux pipe, and a switching plate. The present invention provides a reflux pipe and a switching plate, and monitors the emission content of nitrogen oxides at the smoke outlet of the denitrification reactor through a nitrogen oxide sensor, so that the switching plate can control the connection between the reflux pipe and the smoke outlet of the denitrification reactor according to the emission content of nitrogen oxides, so as to control the emission content of nitrogen oxides in the flue gas and improve the emission standard. The present invention provides a multi-stage catalyst and provides a soot blowing mechanism above the multi-stage catalyst to perform steam soot blowing treatment on the multi-stage catalyst, so as to reduce the problem of ash accumulation in the flue gas blocking the catalyst passage, thereby affecting the catalytic efficiency, and improve the catalytic efficiency of the catalyst.

The present invention relates to a nitrogen oxide sensor fault diagnosis method, device, electronic device, and medium, belonging to the field of automotive technology. The method comprises: obtaining a target nitrogen oxide sensor's transition time from a lean oxygen mode to a rich oxygen mode, and obtaining the number of times the target nitrogen oxide sensor transitions from the lean oxygen mode to the rich oxygen mode, upon determining that the target nitrogen oxide sensor exceeds a dew point, determining that the target nitrogen oxide sensor's oxygen concentration is enabled, determining that the engine is in a normal combustion mode, and determining that the engine exhaust flow rate is greater than a first threshold; and determining whether the target nitrogen oxide sensor is faulty based on the transition time and the number of times the target nitrogen oxide sensor transitions from the lean oxygen mode to the rich oxygen mode. The present invention defines an operating condition suitable for sensor diagnosis, and when the engine enters this operating condition, performs nitrogen oxide sensor fault diagnosis based on the minimum transition time from the lean oxygen mode to the rich oxygen mode, thereby improving the accuracy of nitrogen oxide sensor fault diagnosis.

The utility model provides a nitrogen oxide emission online monitoring and early warning device which comprises an installation shell, two air inlets are oppositely formed in the side wall of the bottom end of the installation shell, an air outlet is formed in the upper end of the installation shell, two filter plates are arranged on the two air inlets respectively, and the filter plates are arranged on the two filter plates respectively. A nitrogen oxide sensor is fixedly arranged in the mounting shell, a suction assembly is arranged on the upper side of the interior of the mounting shell, an air outlet in the upper end of the mounting shell communicates with processing equipment, when the emission amount of nitrogen oxide is detected, the suction assembly is started, the suction assembly sucks surrounding air, and the air enters from the air inlet; the nitrogen oxide sensor monitors the emission amount and concentration of nitrogen oxide in gas in real time, a magnetic adsorption structure of the filter plate facilitates regular cleaning, the internal cleanness and monitoring precision of the device are kept, and the arrangement of the water tank can effectively reduce harmful components in exhausted gas and improve the emission quality.

The invention discloses a nitrogen-oxygen sensor protocol adaptive detection device and method based on machine learning, and relates to the technical field of vehicle emission control. The equipment comprises an upper computer, a CAN (Controller Area Network) communication module, IO (Input / Output) equipment and a controllable power supply module, according to the method, precise matching of protocols is achieved through a three-layer cascade decision-making architecture based on a random forest classifier, stable communication is established in combination with automatic baud rate detection, and distinguishing detection and initialization of front and rear nitrogen oxygen sensors are achieved through dynamic pin state control and power-on and power-off management. And meanwhile, the system has comprehensive data extraction, real-time display and fault diagnosis optimization functions. The method solves the problems of low protocol matching accuracy, insufficient dynamic detection capability, incomplete data extraction, tedious operation, poor system adaptability and the like in the prior art, and has the advantages of high accuracy, strong adaptive capability, high automation degree, good compatibility and the like.

The application provides a method for detecting ammonia leakage of a three-way catalyst, related devices and electronic equipment. The method comprises: obtaining oxygen concentration data in a window, wherein the vehicle is in a steady state condition, and the oxygen concentration data detected by the nitrogen oxide sensor is greater than a preset value; determining whether the time proportion of the oxygen concentration data being less than a first threshold value in the window is greater than a second threshold value, and whether the oxygen concentration distribution is less than a third threshold value; determining that the three-way catalyst has ammonia leakage when the time proportion is greater than the second threshold value and the oxygen concentration distribution is less than the third threshold value; and determining that the three-way catalyst does not have ammonia leakage when the time proportion is less than or equal to the second threshold value or the oxygen concentration distribution is greater than or equal to the third threshold value. The application solves the problem that ammonia leakage in the three-way catalyst cannot be accurately identified in the prior art.

In a method for determining nitrogen oxides and ammonia in the exhaust gas of a vehicle equipped with a nitrogen oxide sensor, measured values ​​from the sensor are received. It is determined whether the measured values ​​show an increasing trend. If so, a lambda value is used to determine whether the sensor readings are representative of nitrogen oxides in the exhaust gas or of ammonia in the exhaust gas. Further measured values ​​from the nitrogen oxide sensor are then assigned to either nitrogen oxides or ammonia, based on the previous determination, until a predefined termination condition is met.Furthermore, an information signal is sent which includes information on whether the further measured values ​​of the nitrogen oxide sensor are still to be attributed to nitrogen oxides or ammonia.

The utility model provides a nitrogen-oxygen sensor testing pipeline which comprises a heat preservation pipeline with two ends arranged in a penetrating mode and a plurality of communicating openings formed in the top of the heat preservation pipeline in a communicating mode, and the communicating openings are matched with nitrogen-oxygen sensors or thermocouples. The output end of the hot air pipeline is communicated with the input end of the heat preservation pipeline; wherein the thermocouple is configured to measure the temperature of air introduced into the heat preservation pipeline. According to the nitrogen-oxygen sensor testing pipeline, the input end of the heat preservation pipeline is communicated with the hot gas pipeline, so that the hot gas pipeline outputs hot gas to the heat preservation pipeline, and after air in the heat preservation pipeline meets the specified temperature, mixed gas is introduced into the heat preservation pipeline, and measurement is started.

The utility model relates to a non-road diesel engine exhaust purification post-treatment structure which is characterized in that a post-treatment body is formed by a DOC (Diesel Oxidation Catalyst) assembly, a DPF (Diesel Particulate Filter) assembly, a mixer and an SCR (Selective Catalytic Reduction) assembly; the DOC assembly comprises a DOC body heat insulation cover, the DPF assembly comprises a DPF body heat insulation cover, the mixer and the SCR assembly comprise a mixer and an SCR heat insulation cover, and the post-treatment outer heat insulation cover is fixed to the post-treatment body. The temperature sensor, the nitrogen-oxygen sensor and the differential pressure sensor are positioned on the post-processing outer heat shield and connect measuring points to the post-processing body; the nozzle is fixed to a nozzle base of the mixer and selective catalytic reduction (SCR) assembly through a bolt, and the urea injection pipe and the nozzle cooling pipe are connected with the nozzle. The utility model has the advantages of light weight, small width and high pollutant conversion efficiency, reduces the post-treatment surface temperature, and improves the installation efficiency of the whole vehicle.

An embodiment of the present invention discloses a calibration method, a calibration device and a vehicle for a nitrogen oxide sensor of a V-type engine. The calibration method for the nitrogen oxide sensor of the V-type engine includes: confirming that the V-type engine is in an operating state; in response to a first nitrogen oxide sensor calibration signal, stopping the operation of the first exhaust cylinder and controlling the second exhaust cylinder to enter an idle condition; counting whether the gas exchange process of the first exhaust cylinder reaches a first preset condition; activating the heating of the first nitrogen oxide sensor, and the first nitrogen oxide sensor obtaining an actually measured standard oxygen concentration value and an actually measured standard nitrogen oxide concentration value; correcting the corresponding relationship between the actually measured oxygen concentration value and the output oxygen concentration value, and correcting the corresponding relationship between the actually measured nitrogen oxide concentration value and the output nitrogen oxide concentration value. The embodiment of the present invention realizes automatic calibration without disassembling the nitrogen oxide sensor, avoids damage to the nitrogen oxide sensor due to thermal stress, and eliminates the man-hours and maintenance costs required for calibrating the sensor.

A double-cavity test system for a nitrogen oxide sensor relates to the technical field of nitrogen oxide sensors and comprises a tubular furnace, a quartz tube, an aluminum oxide tube, an exhaust port, a platinum wire, a gas supply device, an exhaust pipe and other core components. The tubular furnace provides a high-temperature environment of 350-850 DEG C, the quartz tube is inserted into the tubular furnace, one end of the quartz tube is a test end, and the other end of the quartz tube is a gas inlet end; the alumina tube is inserted into the quartz tube, is used for placing a to-be-tested sensor and is hermetically connected with the orifice of the quartz tube through a sealing ring; the platinum wire is used for conductively leading out terminals of a reference electrode and a sensitive electrode of the sensor; the gas supply device comprises a buffer tank, a gas inlet pipeline, a valve body, a Venturi tube, a turbulent flow tube and a turbulent flow net, and is used for supplying test gas to the reference electrode and the sensitive electrode respectively and uniformly mixing and scattering the gas through the turbulent flow device; according to the invention, a stable and uniform test gas environment is provided for the sensor, and the accuracy and repeatability of a test result are improved.

The invention discloses a parameter correction system and method for low emission. The system comprises a gas machine aftertreatment device and an electric control unit. The gas machine post-treatment device comprises a first three-way catalyst converter, a second three-way catalyst converter and a particle trap; a temperature sensor is arranged between the first three-way catalyst converter and the second three-way catalyst converter, and a nitrogen oxide sensor is arranged between the second three-way catalyst converter and the particle trap; the temperature sensor and the nitrogen oxide sensor are electrically connected with the electric control unit respectively; the gas machine post-processing device is used for acquiring a first temperature and an actual oxygen concentration through a temperature sensor and a nitrogen oxide sensor and sending the first temperature and the actual oxygen concentration to the electric control unit; and the electronic control unit is used for correcting the original engine parameters of the engine and the sensor value of the nitrogen oxide sensor based on the first temperature and the actual oxygen concentration so as to optimize the performance and the fuel efficiency of the engine. According to the invention, the accuracy of emission control and the reliability of the system can be improved.

The present invention relates to the technical field of nitrogen oxide sensors and discloses a method, system, and storage medium for increasing the service life of nitrogen oxide sensors. The method comprises the following steps: S1, heating the heating wire of a nitrogen oxide sensor ceramic chip and stabilizing the temperature at a set value; S2, outputting the current heating wire temperature and starting a ceramic chip pump unit control program; S3, monitoring the main pump electrode voltage V0 in the first chamber of the ceramic chip; S4, if V0 > 1V, further heating the heating wire to increase the heating wire temperature; and S5, repeating steps S2 to S4 until V0 ≤ 1V. The present invention changes the state of the existing ceramic chip, which is always at a constant operating temperature, by increasing the temperature of the ceramic chip heating wire when the main pump electrode voltage in the first chamber is about to exceed the failure set value. This increases the activity of the ceramic chip's pump electrode, zirconium oxide layer, and other functional layers, thereby enhancing the oxygen pumping capacity of each chamber and reducing the voltage of each pump electrode, particularly the main pump electrode voltage in the first chamber. This extends the service life of the ceramic chip, thereby improving the product life.

In a method for determining nitrogen oxides and ammonia in the exhaust gas of a vehicle equipped with a nitrogen oxide sensor, a lambda signal is received, and a lambda value is determined based on the lambda signal. This lambda value is representative of the vehicle's air-fuel ratio. Depending on the lambda value, it is determined whether the measured value from the nitrogen oxide sensor is representative of nitrogen oxides in the exhaust gas or whether it is representative of ammonia in the exhaust gas. If the measured value is determined to be representative of ammonia in the exhaust gas, the mass flow rate of the exhaust gas is calculated. Based on the mass flow rate and the lambda value, a nitrogen oxide fraction factor is determined for the measured value. Based on the nitrogen oxide fraction factor, the nitrogen oxide fraction and the ammonia fraction of the measured value are then determined.An information signal is sent that includes information about the nitrogen oxide content of the measured value and the ammonia content of the measured value.

The utility model discloses nitrogen oxide concentration monitoring equipment for a denitration system, which relates to the technical field of denitration systems and comprises a fixing seat, a monitoring cylinder is fixedly connected to the outer surface of the fixing seat, a fixing mechanism is arranged in the monitoring cylinder and comprises a fixing disc, the outer surface of the fixing disc is in sliding connection with the inner wall of the monitoring cylinder, and the outer surface of the fixing disc is in sliding connection with the inner wall of the monitoring cylinder. A limiting ring is fixedly connected to the upper surface of the fixing disc, a fixing plate is slidably connected to the inner wall of the limiting ring, three fixing blocks are slidably connected to the inner wall of the limiting ring, and three fixing frames are fixedly connected to the upper surface of the fixing disc. When the fixing plate moves towards the interior of the limiting ring, the moving block can be extruded, under the extrusion action of the fixing plate, the moving block can move towards the outer side of the limiting ring, and when the moving block moves, the moving block can push the fixing block to move till the fixing block moves into the fixing frame. Therefore, the nitrogen oxide sensor can be conveniently fixed by a worker.

The utility model discloses a tail gas treatment device for nitrogen oxide emission, and relates to the field of tail gas treatment devices for nitrogen oxide emission. The tail gas treatment device for nitrogen oxide emission comprises a tail gas pipeline, a nitrogen oxide storage catalyst, a particulate matter catcher and a selective catalytic reduction catalyst are arranged on the tail gas pipeline, an upstream oxygen sensor is arranged on the upstream of the nitrogen oxide storage catalyst, and a nitrogen-oxygen sensor is arranged on the downstream of the nitrogen oxide storage catalyst. According to the tail gas treatment device for nitrogen oxide emission, a downstream oxygen sensor is omitted at the downstream of the nitrogen oxide storage catalyst, an original nitrogen-oxygen sensor on a vehicle is used for detecting the oxygen concentration and confirming whether regeneration is finished or not, and the nitrogen-oxygen sensor is used for replacing the downstream oxygen sensor, so that the target of replacing the oxygen sensor with a single sensor is achieved; meanwhile, the function of the nitrogen-oxygen sensor is upgraded, and technical reserve is provided for subsequent emission upgrading.

The invention provides a urea injection control method for tail gas after-treatment of an extended-range lean-burn engine, which comprises the following steps: after a tail gas after-treatment system of the extended-range lean-burn engine is powered on and runs, starting a urea system to build pressure, and building the pressure of a urea pump to a first level; working condition parameters of the lean-burn engine are obtained, and an actual nitrogen-oxygen error e is calculated; constructing a feature vector X describing the current working condition of the engine according to the working condition parameters of the lean-burn engine and the actual nitrogen-oxygen error e, and inputting the feature vector X into the three-layer BP back-propagation neural network to obtain dynamically adjusted control parameters; determining a PID basic correction coefficient CPID based on the control parameter and the actual nitrogen-oxygen error e; performing long-term stability compensation on the basic correction coefficient CPID by fusing a temperature-time function to obtain a fusion correction coefficient C; and finally, according to the fusion correction coefficient C and the basic injection amount, the urea injection amount is dynamically adjusted in a zoning mode in combination with nitrogen and oxygen concentration data collected by a nitrogen and oxygen sensor, accurate control is achieved, and the balance between environmental protection standard reaching and fuel economy is achieved.

This application discloses an aftertreatment system, method, and vehicle that can achieve lower emissions while maintaining a substantially unchanged aftertreatment installation space. The aftertreatment system includes: a first nitrogen oxide (NOx) treatment device for reducing NOx and oxidizing and removing it with ammonia; a particulate matter treatment device for capturing particulate matter and catalytically generating nitrogen dioxide; a second NOx treatment device for reducing NOx and oxidizing and removing it with ammonia; a urea nozzle for injecting urea; a temperature sensor for detecting temperature; and a NOx sensor for detecting NOx concentration.

The utility model discloses a nitrogen-oxygen sensor assembly with moisture-proof and dehumidification functions, and belongs to the technical field of nitrogen-oxygen sensor assemblies. A nitrogen-oxygen sensor assembly with moisture-proof and dehumidification functions comprises a shell and further comprises a mounting bolt penetrating through the shell, a supporting plate is slidably connected into the shell, a sensor body is fixedly connected to the supporting plate, and the sensor body and the supporting plate are slidably connected to the mounting bolt; a first air hole is formed in one side of the shell, and a supporting spring is fixedly connected between the bottom of the supporting plate and the shell. A filtering clamping plate is arranged above the shell, and adsorption cotton is fixedly connected into the filtering clamping plate; according to the utility model, the sensor main body can work in a relatively dry and clean environment, the phenomenon that water drops are condensed on the surface of the sensor main body due to temperature difference day and night can be effectively avoided, the vibration of a vehicle can be buffered, and the service life of the sensor is prolonged.

In a method for determining nitrogen oxides and ammonia in the exhaust gas of a vehicle, the vehicle having a nitrogen oxide sensor, measured values of the nitrogen oxide sensor are received. It is determined whether the measured values have an increasing curve. If the measured values have an increasing curve, a lambda value is taken as the basis for determining whether the measured values of the nitrogen oxide sensor are representative of nitrogen oxides in the exhaust gas or whether the measured values of the nitrogen oxide sensor are representative of ammonia in the exhaust gas. Furthermore, until a specified termination condition is met, additional measured values of the nitrogen oxide sensor are assigned to nitrogen oxides or ammonia according to the previous determination as to whether the measured values of the nitrogen oxide sensor are representative of nitrogen oxides in the exhaust gas or whether the measured values of the nitrogen oxide sensor are representative of ammonia in the exhaust gas, and an information signal is transmitted which comprises information as to whether the additional measured values of the nitrogen oxide sensor continue to be assigned to nitrogen oxides or ammonia.

The present invention relates to the technical field of nitrogen oxide sensors, and discloses a water-resistant protective layer for a nitrogen oxide sensor, a nitrogen oxide sensor and a preparation method thereof. The nitrogen oxide sensor chip is included, and a water-resistant protective layer is coated on the outside of the end of the nitrogen oxide sensor chip. The water-resistant protective layer comprises the following components in mass fractions: 100 parts of protective layer powder, 1 to 6 parts of pore-forming agent, 10 to 20 parts of binder, 0.5 to 5 parts of dispersant, 0.5 to 5 parts of defoaming agent and 10 to 20 parts of solvent; the protective layer powder comprises 40 to 60 parts of spinel powder, 20 to 40 parts of alumina powder and 20 to 40 parts of calcium carbonate powder. The water-resistant protective layer of the present invention uses spinel, alumina and calcium carbonate as main raw materials, and can form a microscopic morphology of a flower-like structure after sintering. At the same time, a porous structure is prepared by combining with a pore-forming agent. Coating on the end of the nitrogen oxide sensor greatly improves the hydrophobic property and heat preservation property of the nitrogen oxide sensor, reduces the influence of thermal shock on the nitrogen oxide sensor, and prolongs the service life of the nitrogen oxide sensor.

An exhaust pipe discharges exhaust gas discharged from a hydrogen engine to the outside of a vehicle. An exhaust purification device reduces nitrogen oxides contained in the exhaust gas. A nitrogen oxide sensor acquires a measurement value that reflects the concentration of the nitrogen oxides contained in the exhaust gas, and outputs an output value that is a value that is larger the more the amount of moisture contained in the exhaust gas is subtracted from the measurement value. An injector injects urea water to the exhaust purification device. A control device causes the injector to inject an amount of urea water determined in accordance with the output value and the flow rate of the exhaust gas, in a case where the output value is a predetermined value or more. The control device causes the injector to inject an amount of urea water determined in accordance with the predetermined value and the flow rate of the exhaust gas, in a case where the output value is less than the predetermined value.

A method for operating a nitrogen oxide sensor of an internal combustion engine. When, for a number greater than 1 of operating cycles each including exactly two directly consecutive periods of time, where during a respective first of the periods of time the engine is in fired operation and during the respective second period of time a fired operation of the engine ceases, it is determined that an arithmetic mean of the first periods of time is less than a first threshold value and an arithmetic mean of the second periods of time is less than a second threshold value, a special overrun operating state of a computer is set, where after deactivation of the engine, the computer is kept activated in the special overrun operating state for a longer overrun period, where the nitrogen oxide sensor is kept in a state of operating readiness during the overrun period.

The invention relates to a method for adjusting the mixture formation of an internal combustion engine (10), in particular a hydrogen burner, having a plurality of cylinders (n), having a nitrogen oxide sensor (NOx) in the exhaust gas line, in which a nitrogen oxide sensor signal (NOx sensor) is continuously determined by a control unit (100), the mixture of each cylinder is sequentially enriched starting from one cylinder (n), and the nitrogen oxide sensor signal (NOx sensor) is continuously determined by the control unit (100). A first relative fuel quantity (rk1, n) is determined for each cylinder before the enrichment of each cylinder, a second relative fuel quantity (rk2, n) is determined for each cylinder after the enrichment has been achieved, and the achieved enrichment of each cylinder is cancelled again, in which the enrichment of each cylinder is cancelled until a predeterminable nitrogen oxide limit value (SNOx) is reached, and wherein the first relative fuel quantity (rk1, n) is determined for each cylinder before the enrichment has been achieved, and the second relative fuel quantity (rk2, n) is determined for each cylinder after the enrichment has been achieved. A difference (Dn) between the determined second relative fuel quantity and the determined first relative fuel quantity is determined for each cylinder, an average relative fuel quantity (rkm) is determined as a function of the determined difference, and a mixture formation of the internal combustion engine is adjusted for each cylinder as a function of the determined difference and the determined average relative fuel quantity.