An engine system is provided, which includes an engine, a swirl control valve, an EGR passage, an EGR gas adjusting mechanism, and a controller. The engine includes a cylinder, a piston, and a fuel injection valve. The swirl control valve is provided inside an intake passage and generates a swirl flow inside the cylinder when it closes. When an engine load is at or below a given threshold, the controller controls the swirl control valve to close. While the engine load is the threshold or below, the controller controls the EGR gas adjusting mechanism such that, at a fixed engine speed, an increase rate of an EGR gas amount with respect to an increase in the engine load is lower in a first load range than in a second load range, the first load range being on a higher load side of the second load range and including the threshold.

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.

An engine system is provided, which includes an engine, a swirl control valve, an EGR passage, an EGR gas adjusting mechanism, and a controller. The engine includes a cylinder, a piston, and a fuel injection valve. The swirl control valve is provided inside an intake passage and generates a swirl flow inside the cylinder when it closes. When an engine load is at or below a given threshold, the controller controls the swirl control valve to close. While the engine load is the threshold or below, the controller controls the EGR gas adjusting mechanism such that, at a fixed engine speed, an increase rate of an EGR gas amount with respect to an increase in the engine load is lower in a first load range than in a second load range, the first load range being on a higher load side of the second load range and including the threshold.

The objective of the present invention is to provide a control device for an internal combustion engine that is able to provide a more stable combustion state by suitably setting the amount of recirculated exhaust gas. The present invention is an internal combustion engine control device equipped with air cylinders and an EGR mechanism that returns exhaust gas emitted from the air cylinders to the intake side of the air cylinders, and is characterized by being equipped with an EGR control unit that controls the EGR flow volume of the EGR mechanism, and a humidity detection means that directly or indirectly detects the humidity of outside air supplied to the air cylinders, with the EGR control unit calculating the moisture amount in the outside air and the moisture amount in the recirculated exhaust gas, and controlling the EGR mechanism on the basis of: a stable combustion limit air cylinder mass, which is set in accordance with the combustion state in the air cylinders; the mass of the air introduced into the air cylinders; the mass of the fuel; and the moisture amounts.

An exhaust gas recirculation ejector system for an engine that includes an air conduit coupled to an engine providing charge air to the engine. The air conduit includes at least one bend formed therein. The at least one bend includes a port formed therein. An EGR conduit is coupled to an exhaust manifold of the engine at a first end of the EGR conduit. A second end of the EGR conduit passes through the port and extends into the air conduit at the bend defining an ejector mixing the charge air and exhaust gas before entry into the engine. A pressure sensor is positioned in the bend indicating a pressure of EGR gas exiting the bend.

A temperature sensor differs from a relative humidity sensor in responsiveness when the temperature of air changes. An absolute humidity acquisition unit acquires absolute humidity of air from outputs from the temperature sensor and the relative humidity sensor. A delay adjustment unit is to delay an output from one of the temperature sensor and the relative humidity sensor, which is a high response sensor having a higher responsiveness, and to reconcile change-behaviors of the output from the temperature sensor and the output from the relative humidity sensor in response to a temperature change in air. The absolute humidity acquisition unit acquires the absolute humidity based on the output from the other of the temperature sensor and the relative humidity sensor, which is a low response sensor having a lower responsiveness, and the sensor signal, which is from the high response sensor and delayed in the delay adjustment unit.

An exhaust system with a first and a second exhaust conduit arranged in a parallel flow arrangement. The exhaust system further includes an exhaust gas heat recovery (EGHR) heat exchanger coupled to an exterior of the first exhaust conduit. The exhaust system further includes a first flow control valve controlling the flow of exhaust gas into the EGHR heat exchanger from the first exhaust conduit and a second flow control valve controlling the flow of exhaust gas through the second exhaust conduit.

An apparatus for controlling a low-pressure EGR system may include a driving information detector configured to detect a vehicle driving state, an EGR amount detector configured to detect an amount of external EGR controlled by a low-pressure EGR valve, and a controller configured to control the low-pressure EGR valve and intake and exhaust valves of an engine, based on the result detected by the driving information detector and the EGR amount detector, wherein the controller controls timings of the intake and exhaust valves to decrease an amount of internal EGR introduced into a cylinder through an exhaust port for a predetermined time when the amount of external EGR is decreased.

Methods and systems are provided for measuring exhaust gas recirculation (EGR) distribution among individual engine cylinders. In one example, a method may include fluidly coupling a plurality of intake runners of an engine to a vacuum pump, diverting a portion of intake charge gas from the intake runner to a gas composition sensor with the vacuum pump, measuring an oxygen concentration of the diverted intake charge portion with the gas composition sensor, and estimating an EGR concentration of the intake charge based on the measured oxygen concentration.

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.