Abstract: A NOx catalyst in the exhaust passage of an internal combustion engine is capable of lean burn and adapted to release and reduce absorbed NOx by a reducing agent. Reducing agent supplier is provided in the exhaust passage on the upstream side of the NOx catalyst. A load detector detects the load of an internal combustion engine. Reducing agent addition controller controls the reducing agent addition period and the reducing agent addition interval based on the load of the internal combustion engine, whereby sufficient reducing agent is supplied to the NOx catalyst side independently of the operating condition.

Abstract: The present invention is provided with an NOx catalyst 17 provided in the exhaust passage of an internal combustion engine capable of lean burn and adapted to release and reduce absorbed NOx by a reducing agent, a reducing agent supplying means 19 provided in the exhaust passage on the upstream side of the NOx catalyst 17, a load detecting means for detecting the load of an internal combustion engine 1, and a reducing agent addition control means for controlling the reducing agent addition period and the reducing agent addition interval on the basis of the load of the internal combustion engine 1. The addition period and the addition interval for the reducing agent are controlled taking into account, for example, the degree to which reducing agent adheres to the wall surface in the exhaust passage depending on the velocity, temperature, etc.

Abstract: A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device comprises a particulate trap disposed in the engine exhaust system, an exhaust gas recirculation passage communicating the upstream of the particulate trap in the engine exhaust system with the engine intake system, a control valve for controlling the amount of exhaust gas recirculated through the exhaust gas recirculation passage to be an optimum amount in accordance with an engine operating condition. In the device, an amount of the fresh air introduced into the engine intake system during a fuel-cut is detected, and an amount of particulate trapped by the particulate trap is estimated on the basis of the amount of fresh air detected after the control valve is opened to a predetermined opening degree.

Abstract: An amount of pressurized fluid is pumped by a high-pressure fluid pump to a common rail in an engine by using a multi-functional control circuit (ECU) that improves the controllability of fluid pumped to the common rail such that a target pressure in the common rail is achieved notwithstanding the loss of fuel injected from the common rail into the engine's cylinders nor the variety of pressure losses or deviations occurring throughout the system. The ECU sets a base fluid pumping amount based on a target value of pressure in the common rail and an amount of fluid ejected from the common rail. The ECU also calculates a fluid pumping amount required to cause the actual pressure of the common rail to follow a change of a target pressure of the common rail according to the amount of change of the target pressure.

Abstract: A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device comprises a particulate trap disposed in the engine exhaust system, an exhaust gas recirculation passage communicating the upstream of the particulate trap in the engine exhaust system with the engine intake system, a control valve for controlling the amount of exhaust gas recirculated through the exhaust gas recirculation passage to be an optimum amount in accordance with an engine operating condition. In the device, an amount of the fresh air introduced into the engine intake system during a fuel-cut is detected, and an amount of particulate trapped by the particulate trap is estimated on the basis of the amount of fresh air detected after the control valve is opened to a predetermined opening degree.