An electronic control unit executes a deposit removal operation of removing a deposit accumulated in an intake port of an internal combustion engine. In the deposit removal operation, the temperature of an EGR gas that is recycled to an intake passage is measured or estimated. Then, a variable valve mechanism is operated such that an intake valve is opened in an expansion stroke or an exhaust stroke and the lift amount of the intake valve becomes larger as the measured or estimated temperature of the EGR gas becomes lower. Further, an external EGR device is operated such that the amount of the EGR gas that is recycled to the intake passage becomes larger as the measured or estimated temperature of the EGR gas becomes lower.

Methods and systems are provided for flowing exhaust through a second cooler, arranged downstream of a first cooler and upstream of an intake in an exhaust gas recirculation passage, and extracting condensate for water injection from condensate in cooled exhaust gas exiting the second cooler. In one example, a method may include adjusting the amount of exhaust gas flowing through the second cooler based on an amount of water stored at a water storage tank of a water injection system and engine operating conditions. Further, the method may include selectively flowing exhaust gas from the second cooler to a location upstream or downstream of a compressor in response to engine operating conditions.

An internal combustion engine system includes a first EGR valve to control flow in a first flow path, and a second EGR valve to control flow in a second flow path. A temperature sensor is disposed in the exhaust gas feedstream upstream of the exhaust purifying device, and a controller is in communication with the internal combustion engine and the temperature sensor and is operatively connected to the first and second EGR valves. The controller executes a routine to monitor the temperature of the exhaust gas feedstream upstream of the exhaust purifying device and control the first valve to control flow of exhaust gas to the air intake system via the first flow path and control the second valve to control flow of exhaust gas to the air intake system via the second flow path based upon the temperature of the exhaust gas feedstream upstream of the exhaust purifying device.

A method and system for operating an internal combustion engine equipped with a turbocharger and an exhaust gas recirculation pipe fluidly connecting an exhaust gas line to an air intake duct upstream of a compressor of the turbocharger is disclosed. A value of a parameter indicative of a temperature of an exhaust gas is determined, and an internal recirculation strategy of the exhaust gas is actuated if the determined value is lower than a predetermined threshold value thereof. The internal recirculation strategy includes interrupting a flowing of exhaust gas through the exhaust gas recirculation pipe, and opening an exhaust valve during an intake stroke of a piston of the internal combustion engine.

Methods and systems are provided for a single heat exchanger coupled to a main exhaust passage upstream of one or more exhaust catalysts or in between two exhaust catalysts for exhaust heat recovery and exhaust gas recirculation (EGR) cooling. In one example, in the pre-catalyst configuration of the heat exchanger, during exhaust heat recovery, a portion of exhaust may be routed via the heat exchanger while the remaining portion of exhaust may be routed directly to the exhaust catalysts, and fueling may be adjusted on a per-cylinder basis to maintain a target exhaust air-fuel-ratio at the exhaust catalysts.

A control apparatus 1 for the engine includes an ECU. When the operating region of the engine is in the EGR execution region B, the ECU performs the EGR control (step 2), and performs first coolant temperature control for controlling an IC coolant temperature TWic such that the temperature of intake air passing through an intercooler exceeds a dew-point temperature (step 14). Further, in a case where the operating region of the engine is in the EGR stop region C, the ECU performs second coolant temperature control for controlling the IC coolant temperature TWic such that the temperature of intake air having passed through the intercooler exceeds the dew-point temperature, assuming that the operating region of the engine has shifted to the EGR execution region B (step 17).

Methods and systems are provided for a single heat exchanger coupled to a main exhaust passage upstream of one or more exhaust catalysts or in between two exhaust catalysts for exhaust heat recovery and exhaust gas recirculation (EGR) cooling. In one example, in the pre-catalyst configuration of the heat exchanger, during exhaust heat recovery, a portion of exhaust may be routed via the heat exchanger while the remaining portion of exhaust may be routed directly to the exhaust catalysts, and fueling may be adjusted on a per-cylinder basis to maintain a target exhaust air-fuel-ratio at the exhaust catalysts.

A gas flow control system is provided for at least one cylinder of an internal combustion of a motor vehicle. The gas flow control system includes a supply passage configured to supply gas to the cylinder and an exhaust gas passage configured to remove gas from the cylinder. A bypass passage is configured to connect the supply passage and exhaust gas passage, and a fluid control switch is selectively operable to supply gas out of the exhaust gas passage through the bypass passage into the supply passage in an exhaust gas return operating mode, and to supply gas out of the supply passage through the bypass passage into the exhaust gas passage in a post-air operating mode.

An exhaust gas control apparatus of an internal combustion engine includes a turbocharger including a turbine in an exhaust passage of the internal combustion engine, a post-processing device configured to control exhaust gas, the post-processing device being disposed in the exhaust passage downstream of the turbine, an EGR passage configured to connect the exhaust passage downstream of the turbine and upstream of the post-processing device with a cylinder of the internal combustion engine, and an EGR device including an EGR valve which is disposed in an end portion on the cylinder side of the EGR passage and opens or closes the EGR passage in the cylinder.

A control device for an internal combustion engine adjusts the flow rate ratio between an amount of exhaust gas flowing to an exhaust gas recirculation cooler and an amount of exhaust gas flowing to a bypass passage, which bypasses the exhaust gas recirculation cooler, such that the amount of exhaust gas flowing to the exhaust gas recirculation cooler becomes zero during (i) a predetermined period from a point in time at which the exhaust gas recirculation operation shifts to execution, (ii) a period in which fuel cut is performed and the bed temperature of a catalyst is lower than a predetermined overheat temperature, or (iii) a period in which the flow rate of refrigerant flowing to the exhaust gas recirculation cooler is lower than a predetermined flow rate and the temperature of the refrigerant is lower than a predetermined first temperature.