Methods and systems are provided for exhaust heat recovery and EGR cooling via a single heat exchanger. In one example, a method may include selecting a specific mode of operation of an engine exhaust system with the heat exchanger based on engine operating conditions and an estimated fuel efficacy factor. The fuel efficiency factor may take into account fuel efficacy benefits from EGR and exhaust heat recovery.

A controller for a hydrogen engine is provided. Control circuitry performs, after a stop request for the hydrogen engine, a water reduction process that reduces a proportion of water vapor in exhaust gas. The control circuitry stops the hydrogen engine after operating the hydrogen engine with the water reduction process executed.

A controller for a hydrogen engine is provided. Control circuitry performs, after a stop request for the hydrogen engine, a water reduction process that reduces a proportion of water vapor in exhaust gas. The control circuitry stops the hydrogen engine after operating the hydrogen engine with the water reduction process executed.

A supercharged internal combustion engine is provided that is capable of introducing EGR gas into an intake passage on an upstream side relative to a compressor. When a required WGV opening degree is less than a lower limit value WGVmin in a case in which introduction of EGR gas is started under a situation in which the temperature of an EGR valve is less than or equal to a predetermined value X1, the WGV opening degree is controlled during a protection time period T3 after introduction of EGR gas starts by using the lower limit value WGVmin as the required WGV opening degree.

A control apparatus for an internal combustion engine that includes an EGR channel and an EGR valve is configured, when the internal combustion engine is in a warm-up process and when an intake air flow rate that is a flow rate of air supplied to the internal combustion engine main body is less than or equal to a predetermined value, to open the EGR valve with a minute opening degree that is an opening degree smaller than a minimum opening degree of the EGR valve with which a condensed water in an exhaust-channel-side portion that is a portion of the EGR channel on a side closer to the exhaust channel relative to the EGR valve flows into an intake-channel-side portion that is a portion of the EGR channel on a side closer to the intake channel relative to the EGR valve.

The purpose of the present invention is to provide an engine control system that is capable of promoting mixing of fuel and air during exhaust gas recirculation, thereby suppressing combustion fluctuation of a gasoline engine, such that efficiency and exhaust gas purification can be simultaneously achieved. The engine control system controls an engine and is equipped with an injection device for injecting fuel directly into a cylinder and a recirculation device for recirculating exhaust gas to the intake side. When the temperature of the recirculating exhaust gas recirculated by the recirculation device is high as opposed to when the temperature is low, or when the amount of the recirculating exhaust gas recirculated by the recirculation device is large as opposed to when the amount is small, at least one of the following is executed: advancing of the fuel injection timing (IT_SP (n2) of the injection device; increasing of the fuel pressure (FP) to be supplied to the injection device; reducing the frequency (n) of divided multi-stage injection to be performed by the injection device during the period between intake top dead center and compression top dead center; and reducing of the interval of divided multi-stage injection (IT_RE (n2)).

Methods and systems are provided for operating an exhaust oxygen sensor coupled to an exhaust passage of an internal combustion engine in response to detecting water at the sensor. In one example, a method may include indicating water at an exhaust oxygen sensor positioned in an engine exhaust passage based on a sensor parameter of the exhaust oxygen sensor while operating the exhaust oxygen sensor in a variable voltage (VVs) mode where a reference voltage is adjusted from a lower, first voltage to a higher, second voltage; and adjusting one or more of sensor operation and engine operation based on the indicating water.

Embodiments for estimating intake air humidity in an engine are provided. In one example, an engine method comprises adjusting an engine parameter in response to intake air humidity estimated based on a concentration of one or more engine-out emissions. In this way, one or more exhaust emission sensors may be used to estimate intake air humidity.

Methods and systems are provided for selecting a location for water injection during a water injection event based on engine operating conditions. In one example, a method may include selecting a location for water injection from each of an intake port of each cylinder, an intake manifold upstream of all engine cylinders, and directly into each cylinder based on engine operating conditions. Further, the method may include adjusting water injection at the selected location and engine operating parameters in response the evaporated and/or condensed portion of water.

To provide a controller and a control method for an internal combustion engine capable of reducing the calculation error of recirculation exhaust gas amount due to changes with time of the internal combustion engines, and humidity change of intake air, and also capable of reducing the calculation error of recirculation exhaust gas amount at transient operation. The controller and the control method for the internal combustion engine calculates humidity detecting EGR rate based on intake-air humidity and manifold humidity, calculates humidity detecting opening area which realizes humidity detecting recirculation flow rate calculated based on humidity detecting EGR rate, calculates learned opening area corresponding to present opening degree of EGR valve using learning value of opening area calculated based on humidity detecting opening area, and calculates flow rate of recirculation exhaust gas for control based on learned opening area.