Abstract: A method to control the combustion of an internal combustion engine comprising determining a combustion model providing a spark advance value depending on an objective value of a quantity representing the incidence of a low-pressure EGR circuit, of the rotation speed, of the intake efficiency and of an open-loop contribution of a combustion index; calculating a first closed-loop contribution of the spark advance depending on the combustion index; calculating a second closed-loop contribution of the spark advance depending on a quantity indicating the knocking energy; and calculating the objective value of the spark advance angle to be operated through the sum of the spark advance value provided by the combustion model and of the first closed-loop contribution or, alternatively, of the second closed-loop contribution.

Abstract: A method and a system for controlling an air-fuel ratio for a gas engine are provided. Current outlet pressure of the nozzle is calculated based on current pressure in an intake pipe and a current rotational speed, without detecting the outlet pressure of the nozzle by a sensor. A fluid state of the gas can be determined based on a ratio of the current outlet pressure to the current inlet pressure of the nozzle collected by a sensor, such that a flow rate characteristic corresponding to the fluid state can be selected to calculate power-on duration for the nozzle, so as to set the air-fuel ratio based on the power-on duration. The power-on duration can be calculated based on flow rate characteristics of the gas in respective fluid states, thereby achieving an air-fuel ratio with high accuracy.

Abstract: A vehicle, engine controller and method for coordinating direct split injection of two or more pulses of fuel during a working cycle of a reactivated cylinder which was deactivated in a previous working cycle is described. By using split injection for the reactivated cylinder, the particulate matter and particulate number (“PM/PN”) generated by the reactivated cylinder is reduced.

Abstract: A driver circuit drives a heater associated with a sensor in an exhaust system of a vehicle at a duty cycle. A feedback circuit generates a feedback signal indicating a temperature of the sensor. A ramp circuit outputs a first ramping set point indicating a first rate at which the temperature of the sensor is to be changed over a first time period after an engine of the vehicle is turned on, and a second ramping set point indicating a second rate at which the temperature of the sensor is to be changed after the first time period until the temperature of the sensor reaches a predetermined temperature. An error circuit generates first and second error signals based on the feedback signal and the first and second ramping set points. A controller controls the duty cycle of the driver circuit to drive the heater based on one or more gains.

Abstract: A conditioning apparatus (2) for providing a carrier gas (6), the apparatus including: an inlet (4) for a pressurized inlet gas (6); a cleaning unit (10) to provide clean pressurized gas (6), the cleaning unit (10) including one or more filters to remove solid and/or liquid contamination particles from the pressurized gas (6) and a drying station to remove moisture from the pressurized gas (6); an ionization chamber (16) which ionizes the clean pressurized gas; and an outlet for clean, pressurized, ionized gas; wherein the gas ionized in the ionization chamber (16) has a chemical composition which is substantially the same chemical composition as the inlet gas.

Abstract: A motor vehicle including an exhaust system downstream of an internal combustion engine and which comprises several exhaust gas aftertreatment devices for cleaning the exhaust gas from the internal combustion engine, wherein the exhaust system includes an SCR catalytic converter and at least one additional catalytic converter, wherein the additional catalytic converter is designed as an NOx storage catalytic converter or an oxidation catalytic converter, wherein a control device is provided for controlling at least one operating component of the motor vehicle influencing the temperature of the exhaust gas, wherein the control device is designed to control the operating component for setting the temperature of the exhaust gas depending on at least route information dependent on an expected travel distance and conversion information relating to a temperature-dependent pollutant conversion rate of at least one exhaust gas aftertreatment device of the exhaust system.

Abstract: Systems and methods for removing deposit in an aftertreatment system for an engine are disclosed herein. The method comprises determining an amount of deposits accumulated in the aftertreatment system, determining combustion targets for the engine in response to determining the amount of deposits exceeds a deposit threshold, and modulating an air mass flow for the engine based on the determined combustion targets. The air mass flow can be modulated by changing the position of the wastegate or the geometry of the variable geometry turbine (VGT).

Abstract: Methods and systems are provided for an exhaust aftertreatment system. In one example, a system comprises an air injector positioned to inject air between a first catalyst and a second catalyst in response to an oxygen concentration of an exhaust gas falling below a threshold concentration while exhaust gas temperatures are less than a threshold temperature.

Abstract: A canister assembly for use in an exhaust gas aftertreatment device comprises a cylindrical shell defining a cylindrical axis, a radial direction, and a circumferential direction, a top end and a bottom end. A flow tube is inserted into the top end of the cylindrical shell and terminates short of the bottom end of the cylindrical shell, defining an exit of the flow tube. A mixing bowl member including a symmetrical annular shape about the cylindrical axis and defining a mixing bowl pocket is attached at the bottom end of the cylindrical shell.

Abstract: An emissions control system for a vehicle having an exhaust system with an exhaust gas conduit and a catalytic converter configured to receive exhaust gas from an engine is provided. In one example implementation, the system includes an engine controller configured to control the engine to adjust an air to fuel ratio (lambda) thereof. The engine controller is configured to operate the engine with at least one of the following lambda control strategies (i) a first control strategy comprising operating at a first reference lambda modified by a first percent kick, and a first rich lambda lag time shorter than a first lean lambda lag time, and (ii) a second control strategy comprising operating at a second reference lambda modified by a second percent kick, and a second rich lag time longer than a second lean lambda lag time, to thereby simultaneously meet predetermined NOx and CO emissions targets.

Abstract: Methods and systems are provided for a low temperature NOx adsorber (LTNA). In one example, a method includes initiating a desulfation of an LTNA responsive to an estimated sulfur exposure exceeding a threshold, the desulfation including heating the LTNA to a first threshold temperature while maintaining an exhaust oxygen level above a threshold level throughout the entire desulfation.

Abstract: A control apparatus for an internal combustion engine includes an electronic control unit configured to i) perform a fuel introduction process, ii) calculate a total injection amount in the fuel introduction process, and control each of fuel injection valves based on a required injection amount per cylinder when the fuel introduction process is performed, and iii) perform a cylinder deactivation process for stopping fuel from being injected for one or some of cylinders, and controlling each of the fuel injection valves such that an amount of the fuel obtained by dividing the total injection amount is injected for a cylinder or cylinders other than the one or some of the cylinders for which the fuel is stopped from being injected, when the fuel introduction process is performed.

Abstract: An emissions control system for a motor vehicle that includes an internal combustion engine includes a first selective catalytic reduction (SCR) device and a reductant injector, The system further includes a model-based controller that is configured to calculate a target amount of reductant to inject to maintain a predetermined ratio between an amount of NH3 and an amount of NOx at the outlet of the first SCR device, and to send a command for receipt by the reductant injector to inject the calculated amount of reductant. The model-based controller is further configured to send a command for receipt by an engine controller to influence NOx production by the engine by modifying an engine operating parameter, based on a calculated target amount of NOx at the inlet of the first SCR device.

Abstract: Methods and systems are provided for a flow device shaped to adjust flow to radial positions of an emission control device. In one example, a system may include where the flow device comprises a plurality of inner openings that align while a plurality of outer openings are misaligned to flow exhaust gas proximal to a central axis of an exhaust passage, and where the plurality of outer openings are aligned and the plurality of inner openings are misaligned to flow exhaust gas distal to the central axis.

Abstract: Methods and systems are provided for a urea mixer. In one example, a urea mixer may include a plurality of outlets located adjacent a throat of a venturi passage.

Abstract: Methods and systems are disclosed for operating an engine that includes a knock control system that may determine contributions of individual noise sources to an engine background noise level. The contributions of the individual noise sources may be the basis for establishing the presence or absence of knock in one or more engine cylinders.

Abstract: An electrical connection for an electrical component in an exhaust gas system. The exhaust gas system has a metal casing through which an electrical conductor is routed. The connection has the conductor, an electrical insulation surrounding the conductor, and a metal bushing surrounding the insulation and the conductor, all together extend along a center axis. The insulation extends along the center axis beyond the bushing by an insulation gap of at least 2 mm at least at a first end of the connection.

Abstract: An exhaust system for an internal combustion engine, especially in a vehicle, includes an exhaust gas flow duct (14), a reactant release device (20) for the release of reactant (R) into the exhaust gas flow duct (14) and a catalytic converter device (16) downstream of the reactant release device (20). At least one part of a component surface is provided by a hydrophilic material (34) of at least one exhaust gas-carrying component (12, 22) positioned in the reactant flow path or/and defining this reactant flow path, or/and at least one part of the component surface is provided by a hydrophobic material (40) of at least one exhaust gas-carrying component (12, 18, 22) positioned in the reactant flow path.

Abstract: A power system for a work vehicle includes an engine that generates exhaust gas, an exhaust treatment system that treats the exhaust gas, and an electronic control system coupled to the engine and the exhaust treatment system and implementing a maintenance management system. The maintenance management system is configured to receive a first identifier associated with a first sensor or actuator device installed in the exhaust treatment system, store the first identifier in memory, receive a second identifier associated with a second sensor or actuator device installed in the power system of the work vehicle, compare the first identifier to the second identifier to determine that the first identifier differs from the second identifier and that the second sensor or actuator device is a replacement for the first sensor or actuator device in the exhaust treatment system, and clear any fault codes associated with the first sensor or actuator device.

Abstract: An apparatus for controlling exhaust gas purification may include a front unit communicating with an engine exhaust pipe and having a first catalytic filter; a rear unit communicating with the front unit through a connection pipe and having a second catalytic filter and a bypass channel formed to surround the second catalytic filter; and an actuator to open or close the bypass channel. In particular, one end of the bypass channel is opened or closed and other end thereof is sealed so that the second catalytic filter is heated by a primary filtered exhaust gas filtered by and discharged from the front unit.

Abstract: A method for regulating filling an exhaust gas component (EGC) storage of a catalytic converter (CC) in the exhaust gas (EG) of an internal combustion engine. An actual fill level (AFL) of the EGC storage is ascertained using a first system model (FSM), to which signals of a first EG sensor projecting into the EG flow upstream from the CC and detecting a concentration of the EGC and a second EG sensor, downstream from the CC and exposed to the EG, are fed. A base lambda setpoint value for a first control loop (CL) is predefined by a second CL, which is adjusted to the AFL using the AFL ascertained using the FSM when the voltage of the second EG sensor indicates a breakthrough of rich/lean EG downstream from the CC and an excessively low/high AFL of the EGC storage. Also described is a control unit to perform the method.

Abstract: The instant invention is based on techniques for using non-thermal plasma reactors in both the main exhaust pipe and in the exhaust gas recirculation feed pipe to reduce particulate matter sufficiently to meet EPA limits for PM and enhanced exhaust gas recirculation to meet NOx limits. More specifically, it is based upon the use of a non-thermal plasma device in which a high voltage charge in the plasma reactor causes extremely rapid oxidation of soot particles in the exhaust stream of an engine and further chemical reactions that aid in the reduction of NOx. The primary benefit of this technology is that it can be calibrated to optimize both soot and NOx reduction.

Abstract: Methods and systems are provided for adjusting engine operating parameters in response to an emission output from vehicles within a region. In one example, a method comprises adjusting engine operating parameters in a portion of the vehicles to decrease an emission output therefrom.

Abstract: A fuel oxygen reduction unit for an aeronautical engine is provided. The fuel oxygen reduction unit includes a stripping gas line that provides a stripping gas flow and a plasma reactor in fluid communication with the stripping gas line. The plasma reactor includes a plasma reactor gas inlet that receives the stripping gas flow from the stripping gas line and a plasma reactor gas outlet that provides the stripping gas flow back to the stripping gas line, the plasma reactor configured to reduce a free oxygen content of the stripping gas flow such that an outlet free oxygen content of the stripping gas flow that exits the plasma reactor gas outlet is lower than an inlet free oxygen content of the stripping gas flow that enters the plasma reactor gas inlet.

Abstract: A vehicle includes an engine having a particulate matter removal filter to remove particulate matter, in an exhaust system, and a control device to control the engine such that the vehicle travels in a mode selected from a plurality of modes including a first mode in which both fuel efficiency and ride quality are achieved and a second mode in which the engine is operated at a load higher than a predetermined load. When an accumulation quantity of the particulate matter in the particulate matter removal filter is equal to or more than a threshold, the control device notifies a driver that traveling in the second mode is recommended. When the driver selects the second mode in response to the notification, it is possible to restrain an uncomfortable feeling to be given to the driver, even if the engine is operated at a high load for regenerating the filter.

Abstract: An exhaust purification system of an internal combustion engine 50 comprises: an adsorbent 20 adsorbing HC and NOx in exhaust gas, a catalyst 24 removing HC and NOx, an air-fuel ratio control part 31 configured to control an air-fuel ratio of exhaust gas discharged from an engine body of the internal combustion engine to the exhaust passage, and a temperature calculating part 32 configured to calculate a temperature of the adsorbent. At the adsorbent, a desorption temperature of HC is higher than a desorption temperature of NOx. The air-fuel ratio control part is configured to make the air-fuel ratio a stoichiometric air-fuel ratio when a temperature of the adsorbent is in the vicinity of the desorption temperature of NOx, then make the air-fuel ratio leaner than the stoichiometric air-fuel ratio when the temperature of the adsorbent reaches the vicinity of the desorption temperature of HC.

Abstract: An engine controller executes a fuel introduction process of introducing, in a state in which the crankshaft of an internal combustion engine is rotating, air-fuel mixture that contains fuel injected by a fuel injection valve into the exhaust passage without burning the air-fuel mixture in the cylinder. When the oxygen concentration of exit gas that has passed through a three-way catalyst decreases during the execution of the fuel introduction process, the engine controller executes a stopping process of stopping the fuel introduction process.

Abstract: Internal combustion engine (ICE) exhaust gas treatment systems include the ICE having one or more cylinders configured to receive a mixture of air and fuel defined by an air to fuel ratio (AFR) for combustion therein, a control module configured to control the AFR, a diesel oxidation catalyst (DOC) configured to receive exhaust gas generated by the ICE and oxidize NOx species within the exhaust gas, and a selective catalytic reduction device (SCR) configured to receive exhaust gas from the DOC. Methods for operating and diagnosing such systems include determining, via the control module, a baseline value of a SCR performance parameter which is unsuitable, changing, via the control module, the AFR to change the DOC outlet NO2:NOx ratio, subsequently assessing a second value of the SCR performance parameter, and implementing a control action based on the second value of the SCR performance parameter.

Abstract: A work vehicle includes an engine, a particulate filter, and an oil separator. The particulate filter is connected to the engine to collect particulate matters contained in exhaust gas from the engine. The particulate filter is provided to overlap with the engine when viewed in a height direction along a height of the work vehicle. The oil separator is connected to the engine via a blow-by-gas discharge pipe to catch a liquid component in blow-by-gas from the engine. The oil separator is provided between the engine and the particulate filter to overlap with the particulate filter when viewed in the height direction.

Abstract: A PM detection system has a PM sensor, current detector, and control circuit. The circuit switches of a detection mode and a burning mode. In the detection mode, the control circuit prohibits supply of power to a heater and supplies a voltage between electrodes, and instructs the current detector to detect a current flowing between the electrodes. In the burning mode, the control circuit instructs the heater to generate heat energy to burn PM accumulated on an accumulation part. The control circuit judges PM has remained on the accumulation part when the detected current exceeds a threshold value, and performs the burning mode again. The system further has a pair of current detectors. Each current detector detects a leak current flowing from the heater to the electrodes through an insulation member when the heater generates heat energy. The circuit detects a sensor failure based on the detected leak current.

Abstract: Methods and systems are provided for heating an exhaust particulate filter (PF) to enable filter generation. In one example, a method may include adjusting engine air fuel ratio and injecting secondary air flow upstream of the PF to increase PF temperature. The level of engine air fuel ratio adjustment and the amount of secondary air injection upstream of the PF may be adjusted to account for enrichment induced cooling at a three-way catalyst (TWC) positioned upstream of the PF.

Abstract: A reductant delivery system for an internal combustion engine is arranged to inject a reductant into the exhaust aftertreatment system upstream of a catalytic device. A method for controlling the reductant delivery system includes operating the fluidic pump at a preset state, operating the injector at a zero-flow state, and monitoring, via a pressure sensor, a pressure in the reductant delivery system upstream of the injector to determine a zero-flow pressure. The injector is activated under a preset condition and an actual pressure drop upstream of the injector is monitored. A pressure drop deviation is determined based upon the actual pressure drop upstream of the injector and an expected pressure drop upstream of the injector. An adjustment to the activation of the injector is determined based upon the pressure drop deviation, and the injector is controlled based upon the adjustment.

Abstract: An automotive vehicle includes an internal combustion engine that combusts an air/fuel mixture thereby generating exhaust gas containing particulate matter, and an exhaust after-treatment component that collects the particulate matter. A regeneration system burns off the collected particulate matter thereby regenerating the exhaust after-treatment component. A controller obtains a model of the combustion that is based on a kinetic controlled combustion phase and a mixing controlled combustion phase, and determines a point on the model with respect to current engine conditions that indicates an amount of the particulate matter in the exhaust gas.

Abstract: An exhaust aftertreatment system for use with an automotive diesel engine, the system includes a selective catalytic reduction unit a reagent storage tank, and a reagent distribution system. A reagent fluid is stored in the reagent storage tank. The reagent is delivered to exhaust gases produced by the engine using the reagent distributor. The selective catalytic reduction unit is positioned downstream of the reagent distributor and is configured to remove effluents from the exhaust gases.

Abstract: A gas inerting system employs a carbon dioxide separation unit to remove carbon dioxide and water from an oxygen depleted gas stream generated from a catalytic oxidation unit and subsequently provides a nitrogen rich inerting gas to a fuel tank and/or to a cargo hold. A method of producing an inert gas passes an oxygen depleted gas stream from a catalytic oxidation unit through a carbon dioxide separation unit and provides a nitrogen rich inerting gas for fuel tank inerting and/or cargo hold fire suppression.

Abstract: A system and a method for injector injection error diagnosis include a controller which performs the method having a diagnostic inrush condition control by satisfying air tank pressure of an air tank as an injector injection error diagnosis entry condition while presence or absence of the application of an air compressor is divided between injector injection error diagnosis entry and injector injection error diagnosis execution according to detection of operations of an engine system and an air pressure brake system.

Abstract: An exhaust gas catalyst system that includes at least one exhaust canister including an inlet separated from an outlet with catalytic components positioned between the inlet and outlet. The at least one exhaust canister receives a flow of exhaust gas. The at least one exhaust canister includes a pair of concentric passages formed therein including a central passage and an outer passage. A split flap valve is positioned in the inlet. An actuator is coupled to the split flap valve. A control unit is operably connected to the actuator and selectively moves the split flap valve closing one of the concentric passages and locally heating a portion of the catalytic components.

Abstract: An exhaust system includes a catalytic converter, a particulate filter, a first sensor, and a second sensor. The particulate filter is disposed downstream of the catalytic converter. The first sensor is disposed upstream of the catalytic converter and provides an output identifying a quantity of oxygen in an exhaust flow. The second sensor is disposed downstream of the catalytic converter and upstream of the particulate filter and provides an output identifying a quantity of oxygen in the exhaust flow exiting the catalytic converter.

Abstract: Methods and systems are provided for an exhaust gas arrangement. In one example, a system comprises an air supply device arranged between a first LNT and a second LNT. The air supply device positioned to adjust an air/fuel ratio and a temperature of exhaust gas flowing to the second LNT and devices downstream thereof.

Abstract: Systems, apparatuses, and methods include an upstream exhaust analysis circuit structured to determine a characteristic of an exhaust gas stream entering a nitrous oxide (NOx) storage catalyst; a prediction circuit structured to predict a downstream NOx concentration of an exhaust gas stream exiting the NOx storage catalyst based on a model of a NOx storage capacity or a dynamic response of the NOx storage catalyst; a downstream exhaust analysis circuit structured to determine a downstream NOx concentration of the exhaust gas stream exiting the NOx storage catalyst; and a comparison circuit structured to compare the predicted downstream NOx concentration to the determined downstream NOx concentration, and determine a health of the NOx storage catalyst based on the comparison.

Abstract: An exhaust gas flow control system disclosed relates to the field of mechanical engineering. The system reduces exhaust gas back pressure exerted on an internal combustion engine and prevents excessive heat loss in a radiator. The system comprises a flow regulator connected to an outlet of a silencer and configured to selectively direct the flow of exhaust gases to a metal hydride heat pump and/or a tailpipe. The flow of exhaust gases is directed towards the metal hydride heat pump in case of increased cooling requirement in the vehicle, and to the tailpipe in case of no cooling requirement or maintenance of the metal hydride heat pump. In case of reduced cooling requirement, partial flow of exhaust gases is directed to the metal hydride heat pump and the remaining to the tailpipe. A diverter is configured within the flow regulator to selectively direct the flow of exhaust gases.

Abstract: A fine particle detector includes: a casing part configured to accommodate an object to be heated; an electromagnetic wave generating part configured to generate electromagnetic waves of different frequencies; at least one power sensor configured to measure powers, from the casing part, of the electromagnetic waves that have entered into the casing part; and a fine particle detection controlling part configured to determine, based on the powers of the electromagnetic waves of the different frequencies measured by the at least one power sensor, whether an accumulated amount of fine particles accumulated in the object to be heated is greater than or equal to a predetermined accumulated amount.

Abstract: An engine control device that can suppress thermal degradation of a particulate filter is provided. The device executes a fuel injection control module that restricts the supply of fuel by an injector if a fuel cutting condition is satisfied, an accumulation estimation module that estimates the accumulated amount of soot trapped in a GPF, and a regeneration control module that performs regeneration control for regenerating the GPF by burning soot if the accumulated soot amount exceeds a predetermined setting amount. A fuel cut prohibition line is set in advance and defines a prohibition temperature at which fuel cutting control is to be prohibited in accordance with the accumulated soot amount. The device further executes a prohibition control module that prohibits performance of fuel cutting control by the fuel injection control module if the temperature of the GPF is higher than the prohibition temperature.

Abstract: An oxidation catalyst is described for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a substrate; a first washcoat region disposed on the substrate, wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material; a second washcoat region adjacent to the first washcoat region, wherein the second washcoat region comprises a second platinum group metal (PGM) and a second support material; a third washcoat region disposed on the substrate, wherein the third washcoat region comprises a third platinum group metal (PGM) and a third support material; and wherein either: (i) the third washcoat region is adjacent to the second washcoat region; or (ii) the second washcoat region is disposed or supported on the third washcoat region. Also described are uses and methods involving the oxidation catalyst.

Abstract: Example methods and systems for treating exhaust from an internal combustion engine may generally determine a catalytic converter in an exhaust system is at least partially deactivated by detecting an elevated exhaust temperature and a lean-burn operating condition. In response, a deactivation level of the catalytic converter may be determined, which may be compared with a threshold deactivation level. A magnitude of a temporary rich-fuel operating condition as a response may be determined based upon the comparison. The catalytic converter may be reactivated with the temporary rich-fuel operating condition.

Abstract: A descaling system includes injector arranged to inject cleaning fluid over an inlet for inflow of a fuel-air mixture of an internal-combustion engine and a controller that opens or closes the engine's EGR valve according to parameters of the injected cleaning fluid.

Abstract: A component of an exhaust gas system and a method for exhaust gas after-treatment having a housing with an inlet and an outlet for an exhaust gas, an annular heat exchanger through which the exhaust gas can flow from the inlet in an axial direction and along a first flow path. Downstream of the heat exchanger, an annular catalyst body is arranged inside the heat exchanger and through which the exhaust gas can flow in a radial direction, such that, downstream of the catalyst body, the exhaust gas flows through the heat exchanger in the radial direction and along a second flow path.

Abstract: An exhaust gas purification system and an exhaust gas purification method are disclosed. The exhaust gas purification system is provided with: an injector for injecting urea water, said injector being installed between a combustion device and a selective catalytic reduction (SCR) catalyst; a first gas sensor which is installed downstream of the SCR catalyst, and which detects the NO concentration and the NH3 concentration in exhaust gas outputted from the SCR catalyst; and an opening amount control means for controlling the opening amount of the injector for injecting urea water.

Abstract: A gas alarm for detecting a target gas based on a resistance value of a sensor element comprises a measuring unit to measure a characteristic value of the sensor element, a heating control unit to control a heater to perform a heating process to heat the sensor element, a determining unit to determine, based on the characteristic value, whether the sensor element is in a blunt state in which sensitivity of the sensor element is decreased, and an aborting control unit to abort the heating process to determine whether the sensor element is in the blunt state when a characteristic value of the sensor element measured by the measuring unit after beginning of the heating process by the heating control unit meets a predetermined condition.

Abstract: Rich spike is carried out in an efficient manner. In an exhaust gas purification apparatus for an internal combustion engine which performs lean burn operation, the apparatus includes an NOx storage reduction catalyst, a controller to carry out rich spike, to calculate a storage amount of NOx, to calculate a storage amount of nitrates, and calculate a nitrate ratio, wherein the controller controls a timing at which the rich spike is carried out, based on the nitrate ratio.