Abstract: Provided is an exhaust gas purification apparatus having a control device that monitors the transition of a detection value of each of an upstream NOx sensor and a downstream NOx sensor, and when the NOx purification rate of the SCR catalyst falls to a value of a first threshold or lower, generates an abnormality detection signal indicating that an over storage state has occurred in an SCR catalyst if the amount of change in the detection value of the upstream NOx sensor per unit time is at least a second threshold and the amount of change in the detection value of the downstream NOx sensor per unit time is at most a third threshold.

Abstract: Provided is an exhaust gas purification apparatus having a control device that monitors the transition of a detection value of each of an upstream NOx sensor and a downstream NOx sensor, and when the NOx purification rate of the SCR catalyst falls to a value of a first threshold or lower, generates an abnormality detection signal indicating that an over storage state has occurred in an SCR catalyst if the amount of change in the detection value of the upstream NOx sensor per unit time is at least a second threshold and the amount of change in the detection value of the downstream NOx sensor per unit time is at most a third threshold.

Abstract: A urea water supply system which performs permission determination by a control device based on a first parameter includes a cooling water temperature sensor, and a control device is configured to be able to store a result of the permission determination, and when a system control is restarted after the system control is stopped and a stop period is elapsed, it performs a shortening setting to shorten a time required for the permission determination based on the determination result stored at a time when the system is stopped and a cooling water temperature immediately after restarting.

Abstract: A urea water solution injection system includes a urea water solution injection device for spraying a urea water solution into a portion of an exhaust passageway upstream of a selective catalytic reduction catalyst device, to reduce NOx in exhaust gas discharged from an internal combustion engine. Engine coolant is circulated through the urea water solution injection device to prevent freezing of the urea water solution. A crystal dissolution control unit performs crystal dissolution control on the urea water solution injection device by energizing at a preset amount of energization at a state where a urea water solution supply pump for supplying a urea water solution to the urea water solution injection device is kept stopped, and the crystal dissolution control unit performs the crystal dissolution control for a crystal dissolving energization time calculated in advance, after the engine is started but before a urea water solution is supplied.

Abstract: A urea water supply system which performs permission determination by a control device based on a first parameter includes a cooling water temperature sensor, and a control device is configured to be able to store a result of the permission determination, and when a system control is restarted after the system control is stopped and a stop period is elapsed, it performs a shortening setting to shorten a time required for the permission determination based on the determination result stored at a time when the system is stopped and a cooling water temperature immediately after restarting.

Abstract: A diagnostic device for a sensor 100 provided in an exhaust passage 11 of an internal combustion engine 10 of a vehicle and detecting nitrogen compounds in exhaust gas, the diagnostic device including an offset diagnosis unit 42 which diagnoses, during deceleration of the vehicle in which the internal combustion engine 10 stops fuel injection, an offset amount of a sensor value of the sensor 100 from a zero point based on the sensor value of the sensor value, and a diagnosis prohibition unit 44 which prohibits the diagnosing of the offset amount when a flow rate of the exhaust gas of the internal combustion engine 10 rapidly increases while the offset amount is diagnosed by the offset diagnosis unit 42.

Abstract: An exhaust purification system that includes a selective catalytic reduction to purify NOx contained in an exhaust gas by using ammonia produced from urea water and an NOx sensor to acquire a value of the NOx contained in the exhaust gas, and the exhaust purification system includes: a reach time measurement unit that measures a reach time of the NOx value acquired by the NOx sensor, the reach time being a required time for the NOx value to reach, from a first predetermined determinative NOx value, a second predetermined determinative NOx value, which is higher than the first determinative NOx value; and a determination unit that determines that malfunction occurs in the NOx sensor when the reach time measured by the reach time measurement unit is equal to or shorter than a first predetermined determinative time.

Abstract: An exhaust purification system can prevent a NH3 slip caused by an excessive injection of urea water, and includes: an SCR that purifies NOx contained in an exhaust gas using ammonia, as a reducing agent, produced from urea water; a urea water injection device that injects the urea water into an exhaust passage upstream from the SCR; an estimated-adsorption-amount calculation unit that calculates an estimated adsorption amount of the ammonia adsorbed in the SCR; an injection control unit that executes an injection control of the urea water injection device based on the estimated adsorption amount; and an estimated-adsorption-amount change unit that changes the estimated adsorption amount used for the injection control into a value increased or decreased by a predetermined amount when a predetermined condition is established that can cause a difference between an actual adsorption amount of the ammonia adsorbed in the SCR and the estimated adsorption amount.

Abstract: The exhaust gas purification system includes a SCR, an NOx sensor which is provided on a downstream side of the SCR, and an NOx purifying controller which controls an amount of urea water being ejected to the SCR and performs an abnormality diagnosis based on a detection value of the NOx sensor, wherein the exhaust gas purification system includes an exhaust gas temperature sensor which acquires temperature of the exhaust gas flowing into the SCR, a temperature increasing rate calculating unit which calculates a temperature increasing rate at which the exhaust gas temperature acquired by the exhaust gas temperature sensor reaches a second temperature from a predetermined first temperature, and a prohibiting unit which prohibits abnormality diagnosis by the NOx purifying controller in a case in which the temperature increasing rate calculated by the temperature increasing rate calculating unit is higher than a predetermined determination threshold value.

Abstract: A diagnostic device for a sensor 100 provided in an exhaust passage 11 of an internal combustion engine 10 of a vehicle and detecting nitrogen compounds in exhaust gas, the diagnostic device including an offset diagnosis unit 42 which diagnoses, during deceleration of the vehicle in which the internal combustion engine 10 stops fuel injection, an offset amount of a sensor value of the sensor 100 from a zero point based on the sensor value of the sensor value, and a diagnosis prohibition unit 44 which prohibits the diagnosing of the offset amount when a flow rate of the exhaust gas of the internal combustion engine 10 rapidly increases while the offset amount is diagnosed by the offset diagnosis unit 42.

Abstract: A urea water solution injection system includes a urea water solution injection device for spraying a urea water solution into a portion of an exhaust passageway upstream of a selective catalytic reduction catalyst device, to reduce NOx in exhaust gas discharged from an internal combustion engine. Engine coolant is circulated through the urea water solution injection device to prevent freezing of the urea water solution. A crystal dissolution control unit performs crystal dissolution control on the urea water solution injection device by energizing at a preset amount of energization at a state where a urea water solution supply pump for supplying a urea water solution to the urea water solution injection device is kept stopped, and the crystal dissolution control unit performs the crystal dissolution control for a crystal dissolving energization time calculated in advance, after the engine is started but before a urea water solution is supplied.

Abstract: An exhaust purification system that includes a selective catalytic reduction to purify NOx contained in an exhaust gas by using ammonia produced from urea water and an NOx sensor to acquire a value of the NOx contained in the exhaust gas, and the exhaust purification system includes: a reach time measurement unit that measures a reach time of the NOx value acquired by the NOx sensor, the reach time being a required time for the NOx value to reach, from a first predetermined determinative NOx value, a second predetermined determinative NOx value, which is higher than the first determinative NOx value; and a determination unit that determines that malfunction occurs in the NOx sensor when the reach time measured by the reach time measurement unit is equal to or shorter than a first predetermined determinative time.

Abstract: A clogging detection device includes a urea water sensor which detects temperature in a urea water tank, a pressure sensor which detects pressure in a urea water feed line, an exhaust gas temperature sensor disposed in an exhaust pipe upstream of a selective catalytic reduction device, and a determination unit. When a key switch is turned on, the determination unit performs a startup control to drive a supply pump and increase the pressure in a pipe segment extending to a dosing value. If a detection value of the exhaust gas temperature sensor is no greater than a predetermined temperature, and a detection value of the urea water sensor is no smaller than a freezing temperature, then the determination unit performs emptying control for returning the urea water from the pipe segment to the urea water tank to detect clogging of the pipe segment from the detection value of the pressure sensor.

Abstract: The exhaust gas purification system includes a SCR, an NOx sensor which is provided on a downstream side of the SCR, and an NOx purifying controller which controls an amount of urea water being ejected to the SCR and performs an abnormality diagnosis based on a detection value of the NOx sensor, wherein the exhaust gas purification system includes an exhaust gas temperature sensor which acquires temperature of the exhaust gas flowing into the SCR, a temperature increasing rate calculating unit which calculates a temperature increasing rate at which the exhaust gas temperature acquired by the exhaust gas temperature sensor reaches a second temperature from a predetermined first temperature, and a prohibiting unit which prohibits abnormality diagnosis by the NOx purifying controller in a case in which the temperature increasing rate calculated by the temperature increasing rate calculating unit is higher than a predetermined determination threshold value.

Abstract: An exhaust purification system can prevent a NH3 slip caused by an excessive injection of urea water, and includes: an SCR that purifies NOx contained in an exhaust gas using ammonia, as a reducing agent, produced from urea water; a urea water injection device that injects the urea water into an exhaust passage upstream from the SCR; an estimated-adsorption-amount calculation unit that calculates an estimated adsorption amount of the ammonia adsorbed in the SCR; an injection control unit that executes an injection control of the urea water injection device based on the estimated adsorption amount; and an estimated-adsorption-amount change unit that changes the estimated adsorption amount used for the injection control into a value increased or decreased by a predetermined amount when a predetermined condition is established that can cause a difference between an actual adsorption amount of the ammonia adsorbed in the SCR and the estimated adsorption amount.

Abstract: A urea spray selective catalytic reduction (“SCR”) control system includes an SCR catalyst provided in a discharge pipe of an engine, a dosing valve for injecting urea water at an upstream side of the SCR catalyst, and NOx sensors, wherein the system controls injection of the urea water from the dosing valve. The system includes a plurality of NOx model maps corresponding to an atmospheric pressure condition, an outdoor air temperature, and an engine water temperature, and determines an amount of NOx from each NOx model map on a basis of detection values of an atmospheric pressure detector, an outdoor air temperature detector, and an engine water temperature detector, and controls an amount of injection of the urea water from the dosing valve on a basis of the amount of NOx thus determined.

Abstract: A selective catalytic reduction (SCR) system that can prevent fixation of urea solution to an interior of a dosing valve when the urea solution is not injected through the dosing valve. An SCR system closes a dosing valve when the exhaust gas temperature is lower than a temperature at which an SCR catalyst becomes active and is provided with a fixation prevention system that opens the dosing valve and controls a supply module to feed the urea solution in the dosing valve back to a urea tank to prevent fixation of the urea solution to the interior of the dosing valve, when the exhaust gas temperature is equal to or higher than a temperature at which the urea solution crystallizes and lower than the temperature at which the SCR catalyst becomes active.

Abstract: A clogging detection device includes a urea water sensor which detects temperature in a urea water tank, a pressure sensor which detects pressure in a urea water feed line, an exhaust gas temperature sensor disposed in an exhaust pipe upstream of a selective catalytic reduction device, and a determination unit. When a key switch is turned on, the determination unit performs a startup control to drive a supply pump and increase the pressure in a pipe segment extending to a dosing value. If a detection value of the exhaust gas temperature sensor is no greater than a predetermined temperature, and a detection value of the urea water sensor is no smaller than a freezing temperature, then the determination unit performs emptying control for returning the urea water from the pipe segment to the urea water tank to detect clogging of the pipe segment from the detection value of the pressure sensor.

Abstract: A urea water consumption diagnostic device includes a sensor which detects a level of urea water in a urea water tank, a calculation unit which calculates a cumulative consumed amount based on a detection value entered from the sensor and calculating a replenishment amount based on a change in the detected level of the urea water after a replenishment of the urea water, and a unit which, when a cumulative instructed injection amount of the urea water injected from a dosing valve has become greater than or equal to a determination amount, determines whether or not there is clogging of the urea water by comparing the cumulative consumed amount to the cumulative instructed injection amount. The calculation unit subtracts a level from the changed level of the urea water detected by the sensor upon replenishment to the urea water tank, and stores the resulting level as the replenishment amount.

Abstract: An exhaust gas purification system includes a dosing control unit that controls a supply module to supply urea water between a dosing valve and a urea tank in order to remove urea water accumulated in the dosing valve, when receiving a diesel particulate filter regeneration authorization request from an engine control unit, and then transmits the authorization to the engine control unit, when determining that an NH3 amount of a selective reduction catalyst is less than or equal to a prescribed value.