Abstract: A diesel particulate filter (“DPF”) system is provided with temperature sensors at an entrance side and an exit side of a diesel oxidation catalyst, an SV ratio determining device that determines an exhaust gas SV ratio by measuring flow rate of exhaust gas during the DPF forcible regeneration, and an injector diagnosing device including a heat-generation region determining unit to which detection values of the temperature sensors and a determination value of the SV ratio determining device are input to determine whether or not these values are within a theoretical heat-generation region, and an actual injection amount diagnosing unit that diagnoses a decrease amount in an actual injection amount of an exhaust pipe injector, when the detection values of the temperature sensors and the determination value of the SV ratio determining device are within the theoretical heat-generation region.

Abstract: An exhaust gas purification method of a diesel engine, which purifies exhaust gas while suppressing deterioration in drivability and fuel consumption, including when exhaust gas enters a rich reduction state, opening an EGR valve and closing an intake throttle, if a temperature of an NOx occlusion reduction catalyst is at or above a predetermined temperature, and a vehicle having a diesel engine is decelerating from a speed at or above a predetermined speed, and then closing an exhaust throttle provided downstream of the NOx occlusion reduction catalyst and supplying fuel to the NOx occlusion reduction catalyst as a reductant.

Abstract: An exhaust gas purification method, and system. In order from an upstream side of an engine exhaust passage there are provided, a NOx occlusion-reduction catalyst, a hydrocarbon (“HC”) adsorbing member, and a catalyzed diesel particulate filter or oxidation catalyst. During NOx regeneration control, an air-fuel ratio of exhaust gas in terms of excess air factor is taken to be 0.8 to 1.1 when an index temperature representative of the HC-adsorbing member is a first judgment temperature or less, is taken to be 1.0 to 1.1 when the index temperature is between a first judgment temperature and a second judgment temperature, and is taken to be 0.8 to 1.1 when the index temperature is the second judgment temperature or above, causing an outflow of HC to the atmosphere to be reduced.

Abstract: Provided is a fuel injection control device that affords a wider lower limit range of injection amount by a injector for cylinder outside injection, and that can respond to injection requirements over a wider injection amount range. A fuel injection control device includes: a injector 14 for cylinder outside injection that injects fuel into an exhaust passage 12 of an engine 1, in an amount corresponding to a duty ratio; and a control means 15 for controlling the injector 14 for cylinder outside injection, wherein the control means 15 changes an injector driving frequency upon determining the duty ratio, such that the frequency is lowered, stepwise or continuously, as the required injection amount decreases.

Abstract: An exhaust gas purifier including an NOx catalyst of the selective reduction type and a diesel particulate filter arranged in series, and being disposed in an exhaust passage of an internal combustion engine. The purifier includes a passage for urea supply having a hydrolysis catalyst therein and a passage for hydrocarbon supply having an oxidation catalyst therein. The passages are parallel to each other and separate on an upstream side of both the NOx catalyst and the diesel particulate filter. A urea feeder which supplies urea to the passage for urea supply and a hydrocarbon feeder supplies hydrocarbon to the passage for hydrocarbon supply. The injection of an urea is thereby reconciled with the direction injection of hydrocarbon into the exhaust pipe in a compact space.

Abstract: An exhaust gas purification apparatus including a first exhaust gas treatment member carrying an oxidation catalyst, a three-way catalyst, or a NOx storage reduction catalyst which is used for purifying exhaust gas from an internal combustion engine, a second exhaust gas treatment member having a hydrocarbon (“HC”) storing function disposed on the downstream side of the first exhaust gas treatment member, and a heat dissipating unit disposed between the first exhaust gas treatment member and the second exhaust gas treatment member. An upstream side of the heat dissipating unit is formed into a heat insulating structure, and a further upstream side thereof is formed into a heat retaining structure. Even when an internal combustion engine is accelerating, the exhaust gas flowing into the HC adsorption material can be cooled efficiently and HC can be adsorbed before the temperature of the three-way catalyst or the NOx purification catalyst rises to an HC light-off temperature.

Abstract: A diesel particulate filter (“DPF”) system is provided with temperature sensors at an entrance side and an exit side of a diesel oxidation catalyst, an SV ratio determining device that determines an exhaust gas SV ratio by measuring flow rate of exhaust gas during the DPF forcible regeneration, and an injector diagnosing device including a heat-generation region determining unit to which detection values of the temperature sensors and a determination value of the SV ratio determining device are input to determine whether or not these values are within a theoretical heat-generation region, and an actual injection amount diagnosing unit that diagnoses a decrease amount in an actual injection amount of an exhaust pipe injector, when the detection values of the temperature sensors and the determination value of the SV ratio determining device are within the theoretical heat-generation region.

Abstract: A system for exhaust gas purification including, in an exhaust passage of an internal combustion engine in order from an upstream side: a device for direct injection into the exhaust pipe, an oxidation catalyst, and at least one of a catalyst for NOx removal and a catalyzed diesel particulate filter. A support of the oxidation catalyst is a metallic material or a material having a specific heat not higher than that of the metallic material, and has a structure that mixes the exhaust gas. Regeneration of the NOx occlusion/reduction type catalyst by NOx removal and the forced regeneration of the catalyzed diesel particulate filter by particulate matter removal can occur even when the engine is operated under low-load conditions.

Abstract: An exhaust gas purification device 1 includes an exhaust gas processing device 30 provided in an exhaust passage 11 of an internal combustion engine 10, an in-exhaust pipe fuel injection device 24 provided on an upstream side of the exhaust gas processing device 30 to supply fuel to the exhaust gas processing device 30, a NOx sensor 13 provided on a downstream side of the exhaust gas processing device 30, and a control unit 40 that controls combustion in the internal combustion engine 10 based on operating state of the engine 10. To burn and remove PM trapped in the exhaust gas processing device 30, the control unit 40 causes the in-exhaust pipe fuel injection device 24 to supply the fuel to the exhaust gas processing device 30 and stores a detection value from the NOx sensor 13 as a NOx value at an outlet of the engine 10.

Abstract: An NOx purification system having a selective reduction catalyst, adapted so that even when no ammonia or urea is supplied, NOx is converted to ammonia by a first catalyst including a lean NOx catalyst or a ternary catalyst at ammonia formation control and the ammonia is adsorbed by the selective reduction catalyst disposed downstream and so that by the adsorbed ammonia, there is carried out reduction purification of the NOx contained in the exhaust gas when no ammonia formation control is performed by the selective reduction catalyst. At the ammonia formation control, an ammonia adsorption target amount being a target value of ammonia adsorbed by the selective reduction catalyst is computed, and the ammonia formation control is carried out only when a cumulative value of an ammonia formation amount formed by the first catalyst at the ammonia formation control is under the ammonia adsorption target amount. Consequently, ammonia is stably supplied in just proportion to the selective reduction catalyst.

Abstract: When the operating state of an internal combustion engine (10) is under low load, the supply of unburned fuel is controlled by using post-injection without using in-exhaust-pipe direct injection. Under medium load, the supply of the unburned fuel is controlled by using both the post-injection and the in-exhaust-pipe direct injection. Under high load, the supply of the unburned fuel is controlled by using the in-exhaust-pipe direct injection without using the post-injection. Thus, in air-fuel ratio rich control performed during regeneration to recover the purification capability of an exhaust gas purification apparatus, both black smoke and white smoke are reduced when the supply of the unburned fuel for supplying the unburned fuel into exhaust gas is controlled.

Abstract: A system for exhaust gas purification (1) which comprises, disposed in the exhaust passage (11) of an internal combustion engine (10) in the following order from the upstream side: a device (47) for direct injection into the exhaust pipe, an oxidation catalyst (31), and at least one of a catalyst for NOx removal (32) and a catalyzed DPF (33). The support of the oxidation catalyst (31) comprises a metallic material or a material having a specific heat not higher than that of the metallic material, and has a structure having the function of mixing the exhaust gas. As a result, the regeneration of the NOx occlusion/reduction type catalyst (32) by NOx removal and the forced regeneration of the catalyzed DPF (33) by PM removal can be practiced even when the internal combustion engine (1) is operated under low-load conditions.

Abstract: In an exhaust gas purifier (10) including an NOx catalyst (12) of the selective reduction type and a DPF (14), which are arranged in series, and being disposed in an exhaust passage (2) of an internal combustion engine, provided are: a passage for urea supply (16) having a hydrolysis catalyst (15) deposited therein and a passage for HC supply (18) having an oxidation catalyst (17) deposited therein, the passages (16) and (18) being disposed in parallel to each other on the upstream side of both the NOx catalyst (12) of the selective reduction type and the DPF (14); a urea feeder (20) which supplies urea to the passage for urea supply (16); and an HC feeder (21) which supplies HCs to the passage for HC supply (18). By this, the system for exhaust gas purification (1), which employs both the NOx catalyst (12) of the selective reduction type and the DPF (14), reconciles the injection of an ammonia solution with the direction injection of HCs into the exhaust pipe in a compact space.

Abstract: Disclosed is an exhaust gas purification method, and also disclosed is an exhaust gas purification system (1). The exhaust gas purification system (1) comprises, in order from the upstream side of an exhaust passage (11) of an internal combustion engine (10), a NOx occlusion-reduction catalyst (32) for purifying NOx contained in exhaust gas, an HC-adsorbing member (33) for adsorbing hydrocarbons contained in exhaust gas, and a catalyzed DPF (34) or oxidation catalyst for purifying PM contained in exhaust gas. During the implementation of NOx regeneration control for restoring the NOx occlusion capacity of the NOx occlusion-reduction catalyst (32) in this system, the air-fuel ratio of the exhaust gas in terms of excess air factor is taken to be 0.8 to 1.1 when an index temperature (Tc) serving as an index of the temperature of the HC-adsorbing member (33) is a first judgment temperature or less, is taken to be 1.0 to 1.

Abstract: Provided is a fuel injection control device that affords a wider lower limit range of injection amount by a injector for cylinder outside injection, and that can respond to injection requirements over a wider injection amount range. A fuel injection control device includes: a injector 14 for cylinder outside injection that injects fuel into an exhaust passage 12 of an engine 1, in an amount corresponding to a duty ratio; and a control means 15 for controlling the injector 14 for cylinder outside injection, wherein the control means 15 changes an injector driving frequency upon determining the duty ratio, such that the frequency is lowered, stepwise or continuously, as the required injection amount decreases.

Abstract: When the operating state of an internal combustion engine (10) is under low load, the supply of unburned fuel is controlled by using post-injection without using in-exhaust-pipe direct injection. Under medium load, the supply of the unburned fuel is controlled by using both the post-injection and the in-exhaust-pipe direct injection. Under high load, the supply of the unburned fuel is controlled by using the in-exhaust-pipe direct injection without using the post-injection. Thus, in air-fuel ratio rich control performed during regeneration to recover the purification capability of an exhaust gas purification apparatus, both black smoke and white smoke are reduced when the supply of the unburned fuel for supplying the unburned fuel into exhaust gas is controlled.

Abstract: An NOx purification system having a selective reduction catalyst, adapted so that even when no ammonia or urea is supplied, NOx is converted to ammonia by a first catalyst including a lean NOx catalyst or a ternary catalyst at ammonia formation control and the ammonia is adsorbed by the selective reduction catalyst disposed downstream and so that by the adsorbed ammonia, there is carried out reduction purification of the NOx contained in the exhaust gas when no ammonia formation control is performed by the selective reduction catalyst. At the ammonia formation control, an ammonia adsorption target amount being a target value of ammonia adsorbed by the selective reduction catalyst is computed, and the ammonia formation control is carried out only when a cumulative value of an ammonia formation amount formed by the first catalyst at the ammonia formation control is under the ammonia adsorption target amount. Consequently, ammonia is stably supplied in just proportion to the selective reduction catalyst.